The physiological changes associated with aging deleteriously impact cardiovascular function and regulation and therefore increase the risk of developing cardiovascular disease. There is substantial evidence that changes in the autonomic nervous system and arterial stiffness play an important role in the development of cardiovascular disease during the aging process. Exercise is known to be effective in improving autonomic regulation and arterial vascular compliance, but differences in the type and intensity of exercise can have varying degrees of impact on vascular regulatory responses and autonomic function. There is still little evidence on whether there are differences in the response of exercise interventions to cardiovascular modulatory effects across the lifespan. In addition, acute interval exercise challenges can improve autonomic modulation, although the results of interval exercise on autonomic physiological parameters vary. Therefore, this narrative review focuses on evaluating the effects of acute interval exercise on blood pressure regulation and autonomic responses and also incorporates studies investigating different age groups to evaluate the effects of acute interval exercise on the autonomic nervous system. Herein we also summarize existing literature examining the acute cardiovascular responses to varied modes of interval exercise, as well as to further compare the benefits of interval exercise with other types of exercise on autonomic regulation and arterial stiffness. After reviewing the existing literature, it has been shown that with advancing age, changes in the autonomic nervous activity of interval exercise result in significant impacts on the cardiovascular system. We document that with advancing age, changes in the autonomic nerves lead to aging of the nervous system, thereby affecting the regulation of blood pressure. According to the limited literature, interval exercise is more effective in attenuating arterial stiffness than continuous exercise, but the difference in exercise benefits may depend on the training mode, intensity, duration of exercise, and the age of participants. Therefore, the benefits of interval exercise on autonomic and arterial stiffness improvement still warrant investigation, particularly the impact of age, in future research. Recently, the National Health and Nutrition Examination Survey in the United States showed that approximately 70% of the elderly have hypertension . CardiovArterial stiffness is gradually being recognized as an important predictor and standard reference for hypertension, with aortic stiffness and arterial pulse wave reflection being determinants of elevated central systolic pressure, and arterial stiffness being strongly correlated with elevated blood pressure , 17. PulGiven this, it is crucial to improve the management of hypertension to prevent future cardiovascular morbidity and mortality. A growing amount of research evidence suggests that physical activity interventions are effective and beneficial non-pharmacological treatments for patients with pre-hypertension and hypertension , 26. PreTherefore, this narrative review is an accumulation of the existing literature on the assessment of the effects of acute interval exercise on blood pressure regulation and autonomic responses, and we also incorporate studies investigating different age populations to evaluate the effects of acute interval exercise on arterial compliance and the underlying physiological mechanisms for vascular function regulation. This review of the relevant literature provides a complete compilation of the current knowledge in the field. Here we address the following four main objectives through these following sequential topics, including (1) the effects of aging on cardiovascular regulation; (2) the effects of age differences on cardiovascular responses during acute interval exercise nomenclature; (3) the effects of acute intermittent exercise on autonomic regulation; (4) the comparisons of the acute effects of interval exercise and acute continuous exercise on arterial stiffness. Currently, several studies suggest that HIIT has not been fully recommended by most clinical societies for the prevention or treatment of hypertension. Among the various types of exercise, interval exercise is an effective training modality for improving cardiovascular health, and both interval and continuous exercise can reduce the risk of future cardiovascular disease, but there is no integrated review focusing on such issues. Therefore, we attempted to integrate the currently published evidence on the potential benefits of HIIT on arterial stiffness and the physiological mechanisms involved in modulating vascular function health in different age populations .This review aims to summarize the effects of acute interval training on autonomic nerve response and pulse wave velocity. Studies were limited to those employed human participants and published in English-language, which were searchable in the electronic databases MEDLINE/PubMed, Web of Science (WOS), and Google Scholar conducted from inception to December 2021. The following keywords were used in the searches in conjunction with Medical Subject Heading (MeSH) terms, including autonomic nerve, heart rate variability, pulse wave velocity, and their related terms: acute, interval training, intermittent training, high intensity, sprint interval training, aerobic interval training, continuous training, moderate-intensity continuous exercise and HIIT. The following criteria had to be met to be included for detailed analyses, including a) the exercise intervention duration had to be a single-bout; b) directly compared acute interval training with continuous training; c) clearly defined outcome variables, particularly in autonomic nervous activity, heart rate variability (HRV), PWV as the primary outcomes. The exclusion criteria were as follows: a) articles using non-English-language sources; b) the original text was not obtained; c) statistical data could not be extracted; d) articles with insufficient information; e) documents with unreliable results; f) animal and cell researches.Blood pressure is an essential component of the arterial load. When the heart contracts, the pressure generated by blood entering the aorta against the walls of the arteries is called systolic blood pressure (SBP) . ElevateThe decrease in arterial wall elastin content and increase in arterial wall collagen during aging is accompanied by the development of arterial stiffness, which leads to an increase in SBP and a decrease in DBP . On the Blood pressure increases with aging, and hypertension is considered to be one of the degenerative diseases. Aging also causes an increase in visceral fat and blood leptin, and insulin resistance and excessive secretion of adiponectin impair endothelial cell function and cardiac function . The agiThe carotid to femoral pulse wave velocity (cfPWV) is the gold standard for arterial stiffness measurements and is a reliable predictor of cardiovascular disease morbidity and mortality in the elderly. Aging and prolonged sedentary lifestyle can lead to an increase in PWV, and regular exercise training will help to reduce the risk of negative effects of sedentary lifestyle and aging on PWV . In a st2max for 3 mins and 70% VO2max for 3 min per set; completed 5 sets in total), and changes in arterial stiffness after exercise were measured by analyzing cfPWV; the results of the above study revealed a reduction in cfPWV immediately after exercise (2) performed HIIT  and continuous exercise  (65–75% of HRmax for 41 min). The results of this study showed that HIIT and MCT did not show a significant decrease in cfPWV after exercise , the authors performed 45 min of moderate-to-high intensity interval exercise  and showed that moderate-to-high intensity interval exercise was effective in reducing systolic blood pressure and PWV in the lower extremities immediately after exercise  can be used as a marker to assess cardiovascular autonomic balance, with an increase in LF/HF indicating a predominance of sympathetic balance and a decrease indicating a predominance of parasympathetic innervation . It has gulation .Exercise training causes changes in HRV, and several studies have been conducted to compare the effects of acute interval exercise and continuous exercise on autonomic balance. Several studies have shown that interval exercise has a more positive effect on the acute cardiovascular response than continuous exercise. However, the results of studies comparing interval exercise and continuous exercise on post-exercise effects on autonomic balance are divergent. Andrade et al. compared the cardiovascular and HRV effects of endurance exercise (20 min at 80% of maximum heart rate) and high-intensity interval exercise . Results showed that both the HIIT trial and the endurance trial caused significant decreases in TP, LF, and HF; however, LF/HF showed a significant increase only in the HIIT trial, but no difference in the endurance group . In the Most studies to date have found  that parArterial stiffness is a major contributor to the development of cardiovascular disease, and endurance exercise has been shown to reduce arterial stiffness , 66. How2max) and intermittent walking exercises  were performed in 14 healthy adolescents, and it was found that the carotid pulse conduction velocity decreased by 21% in the intermittent walking group and by 14% in the continuous walking group after exercise; this indicates that intermittent exercise is more effective than continuous exercise in reducing systemic arterial stiffness  appearing to be more effective . FurtherAltogether, interval exercise was more effective than continuous exercise in reducing systemic arterial stiffness, but the degree of effect may vary depending on the subject, exercise activity, intensity, and duration of the intervention on the acute effects of arterial stiffness, and therefore the issue remains to be investigated in subsequent studies. However, when comparing interval and continuous exercise, the exercise benefits of interval exercise appear to be more pronounced .2max gains than MICT, suggesting that interval training is comprehensive evidence for a viable training strategy to improve cardiorespiratory fitness in healthy middle-aged and older adults . However, it has to be noted that there are only a few studies that consider the effect of age differences on these physiological variables in response to acute interval exercise, so the effects of aging on interval exercise-induced acute cardiovascular changes are still unclear. Future studies are warranted to further investigate the acute response of interval exercise on autonomic regulation and arterial stiffness among groups of different ages to fully explore the underlying mechanisms for impacts of aging on autonomic regulation and arterial stiffness to acute interval exercise.W-LL, Y-YL, TM, C-CC, and Y-HL contributed to the conceptualization and edited and revised the manuscript. W-LL and Y-YL contributed to the methodology. C-CC and Y-HL contributed to the collection, synthesis, and interpretation of the data. W-LL, Y-YL, C-CC, and Y-HL drafted the manuscript. All authors approved the final version of the manuscript.This research was partially supported by the Ministry of Science and Technology . The APC was partially funded by the Ministry of Science and Technology (MOST) and the National Taipei University of Nursing and Health Sciences (NTUNHS).The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Excitatory glutamatergic neurotransmission mediated through N-methyl-D-Aspartate (NMDA) receptors (NMDARs) is essential for synaptic plasticity and neuronal survival. While under pathological states, abnormal NMDAR activation is involved in the occurrence and development of psychiatric disorders, which suggests a directional modulation of NMDAR activity that contributes to the remission and treatment of psychiatric disorders. This review thus focuses on the involvement of NMDARs in the pathophysiological processes of psychiatric mood disorders and analyzes the neuroprotective mechanisms of NMDARs. Firstly, we introduce NMDAR-mediated neural signaling pathways in brain function and mood regulation as well as the pathophysiological mechanisms of NMDARs in emotion-related mental disorders such as anxiety and depression. Then, we provide an in-depth summary of current NMDAR modulators that have the potential to be developed into clinical drugs and their pharmacological research achievements in the treatment of anxiety and depression. Based on these findings, drug-targeting for NMDARs might open up novel territory for the development of therapeutic agents for refractory anxiety and depression. Mental health is a major public health challenge in the world today. With the development of science and the economy, people are beginning to pay more attention to various mental health problems in social life. Especially during the coronavirus pandemic, home confinement, social isolation and the resulting economic breakdown have motivated the general public to show increased symptoms of depression, anxiety and stress-related to COVID-19 ,3,4,5. TAccording to the analysis for the global burden of disease study , neuropsHowever, due to a variety of reasons, such as living environment and social status, more than 70% of people who need mental health services still lack access to effective treatments . At the The normal neurological functions of the brain involve many types of neurons and intercellular signaling paths. Glutamate is an important excitatory neurotransmitter in the central nervous system and participates in excitatory conduction in the nervous system. At present, more and more evidence has shown that disorders of glutamatergic neurotransmission can affect normal brain functions and emotional regulation, which is related to the development of a variety of mental diseases ,13,14. T2+). It is widely expressed in the central nervous system—especially in the hippocampus, cortex, amygdala and other brain regions. The family of NMDARs consists of three different subfamilies: GluN1, GluN2 and GluN3 .,52.51,52ntiation ,54. By antiation . NMDARs ntiation ,57. Studntiation . In addintiation . On the contrary, an article in the early 2000s demonstrated for the first time that overactivated NMDARs under abnormal conditions bring about the dephosphorylation of CREB, leading to its inactivation . SubsequIn line with the regulation of synaptic plasticity mediated by NMDARs, the current prevailing theory suggests that the activation of low-dose agonists can preferentially activate NMDARs in the synapse and stimulate CREB, ERK and other molecular targets—thereby activating related downstream pro-survival signaling. High-dose agonists act on both synaptic and extrasynaptic NMDARs, and the activation of extrasynaptic NMDARs counteracts the activation of synaptic NMDARs—suppressing pro-survival signaling and leading to neuronal death . HoweverNowadays, anxiety is one of the most common mental disorders and is also is a widespread symptom of many mental disorders. It is mainly manifested as unconditioned anxiety and conditioned fear. The amygdala, cortex, bed nucleus of stria terminalis (BNST) and ventral hippocampus are all important brain regions involved in the onset of anxiety. The amygdala and its efferent nerves are involved in the acquisition, consolidation and expression of conditioned fear. The functional integrity of the prefrontal cortex (mPFC) has the ability to resist anxiety . The BNSNumerous studies have confirmed that glutamatergic neurotransmission plays a significant role in the pathogenesis of anxiety disorders, which suggest that NMDARs may be important in regulating anxiety-like behaviors ,73. HoweHeretofore, benzodiazepines and selective serotonin uptake inhibitors (SSRIs) have been widely used in the clinical treatment of anxiety disorders, which respectively target γ-aminobutyric acid (GABA) and monoaminergic neurotransmission. Although widely used, these drugs still have common psychotropic side effects, including weight loss, gastrointestinal discomfort and sedation. Moreover, these drugs are not effective for every patient. With the understanding of NMDARs from abundant clinical and preclinical studies, the application of NMDAR-related drugs in the treatment of anxiety disorders has been recommended recently. There are NMDAR modulators in clinical trials for anxiety, as shown in In addition, there have been plentiful preclinical studies on the anxiolytic effects of other agonists or inhibitors of NMDARs. For example, fixed-site injection of the NMDAR competitive antagonist AP5 into the amygdala, middle nucleus, ventral hippocampus—or all of those areas—reduces anxiety-like symptoms in rodents . MK-801,Depression is a prevalent mental disorder and a growing public health problem in society today. It is characterized by low mood, anhedonia and hopelessness, along with other changes such as weight changes, difficulty sleeping and retardation of thinking. Major depression disorder (MDD) is associated with high rates of suicide and is a primary cause of disability worldwide. However, as a complicated mental disease, the pathophysiological causes of depression remain unclear. Some patients usually show depression-like symptoms and other psychotic symptoms. Moreover, multimorbidity (the presence of two or more chronic conditions) can aggravate the risk of depression ,98. EarlGRIN2B, encoding the NMDAR GluN2B subunit in the brain of suicidal depression patients, is increased—suggesting that GRIN2B could be a candidate gene for susceptibility to MDD [As a result of the last two decades of research targeting the glutamatergic system combined with the functional regulation of NMDARs in synaptic plasticity and neural survival, a connection between NMDAR dysfunction and depression has also been suggested. Firstly, abnormal expression of NMDAR-related genes has been observed in patients with depression ,105. Auty to MDD . Meanwhiy to MDD . Additioy to MDD . Under cy to MDD ,114. It y to MDD ,115. Micy to MDD  In line +) enantiomer of ketamine—has been approved for clinical use in depressed patients who are unresponsive to two or more antidepressants [Currently, the most widely used antidepressants are first-generation antidepressants, including monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants (TCAs), and second-generation antidepressants such as selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs)—mainly based on the early monoamine theory of depression. Although these drugs have shown antidepressant effects, there are still approximately one-third of patients who are not sensitive to these classical antidepressants. Additionally, these drugs cannot alleviate suicidal behavior in patients with MDD. With the first study of NMDAR antagonists in depression-like animal models in the 1990s, it was revealed that both the competitive antagonist AP7 and the non-competitive antagonist MK-801 could reduce the behavioral despair duration of animals in forced swimming and tail suspension experiments, showing antidepressant effects . The disressants . Compareressants . (R)-ketressants . More deDextromethorphan, an NMDAR antagonist, has similar pharmacological characteristics to ketamine—suggesting that it could be studied as a potential antidepressant . EsmethaAntidepressant efficacy studies targeting natural herbal medicines are also a much-researched field in antidepressant drug development at present. Previous experiments in our lab have confirmed that a traditional Chinese medicine formula, the Gan Mai Da Zao (GMDZ) decoction, can regulate glutamate levels and NMDAR subunits in the frontal cortex and hippocampus and then ameliorate depression-like behaviors in sucrose preference and open field tests on chronic stress rats . The extAbundant evidence has proven the role of NMDARs in mediating synaptic plasticity and neuronal survival, and numerous studies have also suggested that synaptic dysfunction and neuroplasticity disorders in the brain are involved in pathological processes related to various mood disorders. NMDARs also play a significant role in the pathophysiology of mood disorders due to their extensive presence in the brain and their various subunit combinations that are involved in the regulation of different physiological signals. Therefore, an in-depth intensive investigation of the NMDAR-dependent synaptic and cellular mechanisms that contribute to mood disorders and the identification of the role of these mechanisms in mood improvement are important challenges that could benefit the development of NMDAR modulators for clinical treatments in today’s world. We have mainly focused on two common emotional disorders—anxiety and depression—and have summarized the results of NMDAR modulators in clinical trials and preclinical studies, finding that they have rapid and robust anti-anxiety and antidepressant effects. The unique neuroprotective effects of NMDAR modulators may eliminate the drawbacks of commonly used drugs for the clinical treatment of mood disorders. The discovery of natural drugs that can act on the NMDAR has also helped to enrich the pharmacology of NMDARs. However, in the process of clinical research, it is also necessary to consider whether NMDAR modulators induce other mental disorders when they function though the modulation of the activity of NMDARs; for example, whether non-competitive NMDAR antagonists could cause NMDAR hypofunction when patients got treatment and induce behaviors of symptoms of schizophrenia such as hallucinations and delusions. Drugs targeting NMDARs could open up a promising new frontier for future research to meet the needs of patients with major anxiety and depression, as well as patients with treatment-resistant depression.Aside from the anxiety and depression mentioned above, NMDAR modulators also have great potential in the treatment of other psychiatric disorders. Schizophrenia has a high prevalence in the general population, with clinical characters of affective and neurocognitive impairments. Ketamine and PCP, which were developed as dissociative anesthetics, can induce schizophrenic-like symptoms in healthy humans—demonstrating that these effects are mediated via noncompetitive antagonism of NMDARs . All of


Blood pressure (BP) monitoring can be performed either invasively via arterial catheterization or non-invasively through a cuff sphygmomanometer. However, for conscious individuals, traditional cuff-based BP monitoring devices are often uncomfortable, intermittent, and impractical for frequent measurements. Continuous and non-invasive BP (NIBP) monitoring is currently gaining attention in the human health monitoring area due to its promising potentials in assessing the health status of an individual, enabled by machine learning (ML), for various purposes such as early prediction of disease and intervention treatment. This review presents the development of a non-invasive BP measuring tool called sphygmomanometer in brief, summarizes state-of-the-art NIBP sensors, and identifies extended works on continuous NIBP monitoring using commercial devices. Moreover, the NIBP predictive techniques including pulse arrival time, pulse transit time, pulse wave velocity, and ML are elaborated on the basis of bio-signals acquisition from these sensors. Additionally, the different BP values  of the various ML models adopted in several reported studies are compared in terms of the international validation standards developed by the Advancement of Medical Instrumentation (AAMI) and the British Hypertension Society (BHS) for clinically-approved BP monitors. Finally, several challenges and possible solutions for the implementation and realization of continuous NIBP technology are addressed. Outstanding technological capabilities in the present day have contributed significant impacts to the healthcare sector via continuous monitoring of vital signs such as blood pressure (BP) for home users. These health monitoring tools, such as cuff sphygmomanometers for measuring BP non-invasively, are extensively used by patients with various health conditions, such as cardiovascular-related diseases and diabetes, or even by subjects with no history of ailments.BP is a measurement of force exerted by the heart against the arteries during the pumping of blood and it is used by health practitioners to evaluate a patient’s current state of health. To date, there are two clinical, gold-standard ways of monitoring BP. The first one is performed invasively in intensive care units (ICUs) or operative ward environments via arterial catheterization, while the second approach is more flexible because it measures BP non-invasively and so it is more suitable for clinical or at-home applications using the cuff sphygmomanometers. In comparison to the invasive way, the non-invasive blood pressure (NIBP) measurement method shows superior performance in terms of ease of use, low cost, portability, reproducibility, and simplicity in that it does not require the judgement of experts to understand the estimated BP.For an individual with non-existing conditions, the ideal systolic blood pressure (SBP) and diastolic blood pressure (DBP) according to the American Heart Association are less than 120 and 80 mmHg, respectively . SeveralThe first experimental realization of non-invasive BP monitoring, by von Basch in 1876 , used a Currently, the cuff-based technique possesses few limitations that are still considered as ongoing roadblocks in clinical medicine for finding suitable alternatives to measure BP unobtrusively and targeted for general populations. This is because patients often experience pain and discomfort  during BTo the best of our knowledge, the cuffless NIBP sensors are yet to be validated in a way that can be readily implemented as the gold standard of the NIBP monitoring model. The alternatives have received considerable critical attention as they are capable of estimating continuous and accurate BP results with the aid of advanced technology such as machine learning (ML), and these can be expanded for remote and ambulatory (24 h) monitoring ,27 throuThis review summarizes available state-of-the-art NIBP sensors, as displayed in NIBP sensors offer continuous monitoring of BP, which is an important biomarker in assessing individual state of health in real time. In this section, the various NIBP sensors based on optical, electrical, pressure, and ultrasound principles are reviewed.2) monitoring under anesthesia [Glenn Allan Milikan devised the first oximeter in 1940 and introduced the term “oximeter” a year later . In 1973esthesia . Recentlesthesia ,32.The generation of a PPG pulse is based on an optical principle that involves the interaction between a light-emitting diode (LED) and a photodetector (PD). LED emits light on peripheral tissues, and then the light is scattered to the extent where only a proportion of the light is absorbed by the tissues. PD measures differences in absorbed light as arterial blood volume changes during a cardiac cycle . TypicalFor PPG-based BP prediction using PTT, two PPG sensors are placed further from each other either at the same location or multiple peripheral sites. These sites could be from the temporal artery (forehead), carotid artery (ear and neck), brachial artery (arm), radial artery (wrist and finger), posterior tibial artery (ankle), and dorsalis pedis artery (foot) . HoweverFinapres  is an example of a commercialized digital PPG finger cuff with a pre-installed infrared (IR) photocell, a manometer, an automated inflated cuff, and a BP monitor. The utilization of Finapres as an arterial BP estimator was based on a volume clamp to measure a continuous beat-to-beat finger BP waveform and generate SBP, DBP, and MAP digitally. A model of continuous BP prediction was developed in  for 27 hPPG sensors display several limitations that require extensive efforts to improve the efficacy and feasibility of PPG as an alternative for NIBP monitoring. One work on BP estimation based on dual PPG sensors observed a dramatic reduction of PWV variations only after the applied pressure at the measurement site was kept constant. This shows that the susceptibility of the PPG signals to applied pressure might contribute to substantial effects, such as artificial alteration of the PPG waveform . Loss ofElectrocardiogram (ECG) has been employed by clinicians to measure cardiac physiological signals non-intrusively, including heart rate (HR) estimation, heartbeat rhythm regularity assessment, and CVD diagnosis. Even though the ECG waveform only displays the heart’s electrical activity and reflects no BP information , the intThe ECG waveform consists of electrical cardiac depolarization and repolarization phase recordings measured in the time domain , and theThere are many readily available cardiograph monitors in the market, but only a few of them incorporate ECG and PPG in the same device, such as CardioQVARK and MAX86150 . CardioQVARK was developed by Russian engineers to monitor real-time cardiovascular parameters for at-home patients. For example, BP values of 500 participants in  were fouArtifacts contamination is a key challenge for the implementation of ECG signals in BP monitoring field, especially because this sensor is sensitive to non-constrained environments that are filled with potential sources of noises, including motion artifact, incorrect electrode placement, and baseline wander. Hence, several methods have been suggested to address this issue, such as using ML models and advanced signal processing algorithms.Arterial tonometry (AT), based on the applanation tonometry principle, is an established method of measuring arterial BP non-invasively, in which pressure is given toward the arterial line causing the compression of the arteries, thus producing arterial pressure waveforms. BP can be estimated through direct and indirect techniques of AT .For the direct method, BP values are estimated from the recording of pressure waveforms at the common carotid artery. The reason behind this process is that the waveform shape of the common carotid artery resembles that of the aorta, giving an advantage to the prior method in terms of accessibility . Thus, t® tonometer sensor  and a cuff sphygmomanometer to determine which modality best predicted chronic kidney disease (CKD) obtained from 10,197 subjects [® employment, it may be a great surrogate to the current  standard BP monitoring tool and more efforts can be done to study its usability as a CKD risk predictor especially in women, as this group experiences the inevitable process of menopause, which may contribute to stiffer aorta.BP monitors in the market that operate with AT setting include PulsePen  , Sphygmosubjects . It was However, the pulse waveforms obtained from AT contain limited information, such as pulse pressure recordings, and this method is incapable of providing absolute SBP and DBP values , systemiThe prediction of BP using an ultrasound (US) approach is not supported by theoretical principle; nevertheless, algorithms such as PWV and Moens–Korteweg (MK) equations are significant for enabling the indirect estimation of BP values as well as solving computational related problems . US is bA previous study  reportedThere are various groups currently working on US-based BP detection studies through different approaches. Meusel et al.  comparedIn a different approach, Zakrzewski et al.  measuredSeveral weaknesses of the US method for NIBP monitoring are cumbersome US probe placement procedures, the need to have skilled operators, sensitivity to motion, and bad contact between the US probe and the skin area . This isOverall, regardless of the sensing mechanisms, these NIBP sensors offer promising potentials for guiding future research of continuous BP prediction. For example, the widespread usage of pulse oximeters in a clinical environment indicates the feasibility of optical-based sensors capturing a human bio-signal, even though the BP estimation using PPG is still in its infancy stage. In addition, the integration of PPG and ECG in the same platform provides valuable discoveries including high BP signals quality, thus showing the importance of ongoing efforts to improve the reliability of this system. Conversely, low research works are reported on the AT-based BP prediction approach due to several factors, including poor DBP estimation accuracy and sensor errors. From the aspect of US BP monitors, increasing attention is being paid to improve device portability, low cost and easy operation since the current ones in the market are not suitable for continuous BP monitoring.Having investigated the different sensing mechanisms of NIBP sensors, this section discusses the prediction approaches of continuous BP monitoring based on acquired signals from NIBP sensors and compares the SBP, DBP, and MAP results estimated using various ML algorithms in several reported works based on the international protocols for clinical verification of BP monitoring devices.One way of predicting BP values continuously is by performing the PAT calculation on acquired pulse signals from PPG and ECG type of sensors. PAT can be expressed as the time taken for the pulse wave to travel from the heart to the peripheral location. In general, the PAT at the specified points of the PPG signals was derived from the beginning of the heartbeat at the R-peak of the ECG, as displayed in The points could be from the R-peak of the ECG signal to the foot of PPG :ted as L ,71. h isdistance .Li et al.  comparedBased on the above-mentioned techniques, it can be deduced that they are PPG-dependent, although several studies explored the sole utilization of ECG signal. The computational complexities of such studies are often higher and require knowledgeable experts. Nevertheless, there is no clear evidence that BP is best estimated by PAT, PTT or PWV. Hence, more research is required to understand these methods and evaluate the accuracy according to the international validation standards.ML is the ability of self-learning from past experiences to generate desired results, such as prediction, classification, or feedback . This tet-test [Once the signal acquisition process completes, pre-processing is usually performed on the signals prior to prediction analysis to minimize noises by filtering . Figure t-test  and the t-test . The sigt-test . The fint-test .BP prediction based on ML approaches covers the estimation of MAP, which is significant aside from SBP and DBP values for validation of the proposed models to estimate BP. MAP is defined as the average arterial pressure measured in a complete cardiac cycle, which consists of systole and diastole phases , as dispThe most frequently used algorithms in ML for BP prediction are random forest (RF) and k-nearest neighbors (KNN), among others. For instance, RF is made up of multiple decision trees and provides prediction based on the average votes from the trees. Meanwhile, KNN learns from storing information and provides output based on comparative resemblance of datasets using the closest neighbours concept . SeveralWu et al.  attempteMejía-Mejía et al.  extracteDL is an extension of ML. It is a powerful method that enables complicated automated feature extraction with high performance in big data, and it reveals implicit information and automated learning without hand-crafted feature selection because of neuron layer stacking, better known as deep NN . DL is aFor BP estimation works based on bio-signal processing, convolutional neural network (CNN) and long short-term memory (LSTM) networks are among of the DL models that are frequently adopted by the biomedical engineers and researchers. Several investigations on BP prediction using these models are surveyed as follows. CNN is frequently utilized to learn trends of signals and to identify significant features within the signals , in suchMeanwhile, LSTM network can memorize previous learnings and generally utilize sequential data . It can The reported learnings obtained from several studies were compared to identify which method satisfies the passing criteria for AAMI and portrays high prediction accuracy at par to the reference of NIBP measurement with a cuff sphygmomanometer. The proposed NIBP device is considered as AAMI approved when respective performance metrics display less than or equal to 5 mmHg for MAE and 8 mmHg for SD with at least 85 subjects . Table 1Continual research on the development of NIBP technology faces the following key challenges for replacing the current physical measurement protocol: source of data, motion artifacts of PPG, calibration performance, dataset size, learning selection, sphygmomanometer variation models, and hampering of wires. Therefore, further efforts are needed to address these challenges and improve the efficiency of NIBP technology for continuous BP monitoring.To begin with, online open-source databases have been widely employed in continuous BP prediction, but more offline data are required. For example, the inclusion of healthy subjects in the investigations are needed to resolve this challenge. Although MIMIC data collection requires minimal effort, the evaluation of BP accuracy is still scarce. This is because the data extracted from MIMIC contains the records of critically ill patients obtained from the ICU. Moreover, there is a loss of some of the physiological parameters during offline signal analysis, which may be caused by the ingestion of drugs and medication by patients. Hence, by selecting human volunteers as the mean of extracting BP-related features, BP variation and discrepancies can be reduced to make a good prediction.The next challenge is the contamination of motion artifacts in the majority of NIBP sensors. Most of the data acquisition should be performed stationarily without any disturbance to avoid any distorted signal or loss of significant parameters. To address this issue, the proposed method can be trained using datasets with various kinds of interferences. As the learnings capture and store the information, they can be further tested in dynamic environments with no applied constraints to evaluate the robustness and flexibility of these models in providing great estimation. Additionally, signal processing analysis can be performed on the raw signals to smoothen the signals and remove any implicit noises and baseline wander.Furthermore, there is a lack of an established calibration system for continuous BP monitoring. Some studies unfairly justified their novel approaches as high satisfactory without performing the proper calibration with the reference measurement of NIBP, but instead validated with other NIBP sensors such as volume clamp-based PPG, AT or an unmentioned reference source. This step should be rectified by establishing a calibration system and computing the difference in estimated BP using the proposed techniques from ground truth values. If there is any visible anomaly in the BP reading, some optimizations can be carried out to enhance the performance of the devised system as well as improve the accuracy of the predicted BP.Moreover, another challenge associated with NIBP implementation is the small size of datasets and the imbalanced number of volunteers, which is dominated by healthy subjects rather than diseased patients. To mitigate this matter, the incorporation of larger demographic datasets may help to identify any unusual pattern of pulse waveform, which is essential for BP analysis. Some of the inclusion criteria, including age, gender, height, weight, mental health, and history of disease, are significant prior to data acquisition to ensure the initial datasets are adequate for further analyses. Additionally, learning selection plays an important role in this part because advanced learnings, such as DL or hybridization of learnings, enable better output generation. It is worth noting that the suggested solution can be more complicated and difficult to understand for novice users, and that it can increase the computational complexity with longer training time and bigger computational memory to store the vast amount of data.Another key challenge of NIBP technology integration is the irrelevant interchangeability of the cuff sphygmomanometer, which explains why BP values of the same subject vary when measured with different BP monitors. One of the possible reasons is that the algorithms implemented for BP interpretation are developed exclusively for every model and remain confidential to the consumers or among developers. Hence, more research efforts are currently working on seeking for the best possible alternative to measure continuous BP non-invasively and suitably for everyone through a standardized predictive-based technique using the PAT, PTT or PWV approach, and to fuse it with available learnings.Finally, the traditional BP monitoring system configuration usually involves many wires and may cause some interference, causing less accurate BP estimation, regardless of motion disturbances. This set-up is not viable for continuous monitoring and can be further minimized into compact size with the embedding of electronics into Internet-of-Things platforms. This explains the abundance of research works exploring the aspects of material selection and structural engineering of wearable sensors to integrate this powerful device into real-time human health monitoring and improving the life quality of mankind.Rapid technological advances have led to the development of optical, electrical, pressure, and ultrasonic sensors in searching for the current (gold) standard NIBP replacement that can capture data continuously in real time and can be accessed remotely. These sensors portray promising features, such as improved prediction accuracy, continuous data measurement, and mercury-free operation. Successful BP estimation using algorithms is a step forward toward the emergence of smart human health monitoring to keep up with the future trend through the development of accurate, cost-effective, comfortable, and clinically-approved continuous NIBP monitoring systems. In conclusion, the realization of continuous NIBP technology is possible considering the existing shortcomings are taken into account and resolved systematically for the enhanced future of human health monitoring and seamless data transmission.


Policymakers around the world are grappling with an influx of rapidly changing science and new treatments in the area of medications and health technology. Much of their decisions have historically relied on randomized controlled trial (RCT) data for drug assessments. Over the past decade, it has become important for many decision-makers to realize that the RCT design may not reflect real-life clinical practice as the trial populations may exclude important patients seen in clinical practice. More importantly, the RCT is unable to answer questions related to rare adverse events, optimal use, and access. Therefore, the use of real-world data in the field of pharmacoepidemiology has, in many cases, stepped up to help policymakers fill these gaps. In this special topic, we aimed to gather a global cross-section of various papers that showcase the power of pharmacoepidemiology in helping shape policy and clinical practice.We set out to cover the many areas that pharmacoepidemiology can be used to shape and inform policymakers, including understanding beneficial and adverse drug effects of medications, drug utilization, real-world effectiveness, clinical effects of drug-drug interactions, effects of medication non-adherence, and the impact of policy changes on drug utilization. We were able to do just that and covered many of these topic areas. Excitingly we received work from over eight different countries, each leveraging unique data sources and study designs that truly highlight the breadth of work that can happen in this field. Most importantly we received work that showcased the ability for pharmacoepidemiology to be used in studying drug safety, policy, and clinically relevant questions.Perreault et al.), drug-drug interactions between methadone and antidepressants , use of antiseizure medications among pregnant women , and prescribing cascades related to anticholinergic medications . Authors asked central and potentially clinically-influencing questions related to predicting medication adherence after a myocardial infarction , repurposing of hydralazine to reduce phelbotomy , comparison of time to treatment intensifications for diabetes treatments with newer drugs , and treatment failure with long-acting antipsychotics .Specifically, we included a number of exciting papers on the safety of drugs with important clinical applications in the area of anticoagulants , opioid use at the end-of-life , biosimilar uptake of insulin glargine , trends in psoriatic arthritis medication use , and the impact of COVID-19 on psychotropic medication use . And lastly, this topic area showcased ongoing work related to novel data sources and use of data such as emerging use of Drug utilization research in barzil , and use of pharmacy and registry data .Papers also showcased the ability to assess policy-relevant questions such as the impact of policies on fentanyl prescribing (With the ubiquity of big data and limitations of RCTs, decision-makers and clinicians are in need of supportive evidence to support the assessment of drug effectiveness, safety, optimal use and policy decisions. This special topic showcased the global power of pharmacoepidemiology for answering this call.


The second and third trimesters of pregnancy are crucial for the anatomical and functional development of the gastrointestinal (GI) tract. If premature birth occurs, the immaturity of the digestive and absorptive processes and of GI motility represent a critical challenge to meet adequate nutritional needs, leading to poor extrauterine growth and to other critical complications. Knowledge of the main developmental stages of the processes involved in the digestion and absorption of proteins, carbohydrates, and lipids, as well as of the maturational phases underlying the development of GI motility, may aid clinicians to optimize the nutritional management of preterm infants. The immaturity of these GI systems and functions may negatively influence the patterns of gut colonization, predisposing to an abnormal microbiome. This, in turn, further contributes to alter the functional, immune, and neural development of the GI tract and, especially in preterm infants, has been associated with an increased risk of severe GI complications, such as necrotizing enterocolitis. Deeper understanding of the physiological colonization patterns in term and preterm infants may support the promotion of these patterns and the avoidance of microbial perturbations associated with the development of several diseases throughout life. This review aims to provide a global overview on the maturational features of the main GI functions and on their implications following preterm birth. We will particularly focus on the developmental differences in intestinal digestion and absorption functionality, motility, gut–brain axis interaction, and microbiomes. The maturation of the gastrointestinal (GI) system in full-term and preterm human infants is an area of great interest from both a nutritional and medical practice standpoint. Particularly in preterm infants less than 28 gestational weeks (GW), delivery constitutes a nutritional emergency in which the infant has high and difficult-to-meet nutritional needs . A contrThe disorders of GI ontogenesis, along with other factors such as early postnatal stress, microbiota alterations induced by infections, or early antimicrobial use in the Neonatal Intensive Care Unit (NICU), result in an impaired activation of intestinal peristalsis and of the gut–brain axis . DisturbNewborns need the structural and functional maturation of the GI tract for digestion and absorption of the nutrients from colostrum and breast milk. They also need a complete development of intestinal motor function which includes suck–swallow coordination, continence of the gastroesophageal sphincter tone, adequate gastric emptying, and intestinal peristalsis. Full-term babies can acquire adequate amounts of nutrients to promote the rapid growth that occurs shortly after birth. However, half of preterm infants are delayed in reaching full enteral feeding volumes and have gastroesophageal reflux, gastric residuals, and constipation due to delayed gastric emptying, prolonged bowel transit, abdominal distension, and delayed passage of meconium, all of which are GI functions describing immaturity . There aIn this review we will provide a global view of the basic intestinal function present in the GI tract at birth in term and preterm infants. We will pay particular attention to developmental differences in intestinal digestion and absorption functionality, motility, gut–brain axis interaction, and microbiomes.2. This surface is in contact with food, microbes, and other potentially antigenic components, and plays a key role in the digestive and absorptive processes [The human GI tract is an organ with one of the largest surface areas of the body. The size of the intestine exhibits an estimated one-thousand-fold increase from 5 through 40 GW . Autopsyrocesses . The larrocesses .The GI tract is comprised of several structures that extend though the oropharynx, esophagus, stomach, duodenum, jejunum, ileum, cecum, and colon. Each one of these performs discrete functions critical to health. Thought to be primarily an organ of digestion, absorption, and excretion of waste, it contributes to overall health in a much broader sense . In addiProtein sources for term and preterm infants are comprised of two major components, whey and casein. Digestion of these proteins is initiated in the stomach, where parietal cells secrete hydrochloric acid which, in combination with activation of the proenzyme pepsinogen, denatures some of these proteins. Parietal cells are present by the late first trimester of pregnancy, and they actively secrete gastric acid by the second trimester. ,18. AfteOther major enzymes are produced by the pancreas during this time. These include trypsinogen, chymotrypsinogen, and carboxypeptidase, all of which are zymogens that require activation by enterokinase, which is produced by the upper intestinal epithelial cells. By 24 GW, enterokinase is active at 25% of the level found in older infants . These eThis leads to the question of whether hydrolyzed protein formulas are better tolerated, thereby providing enhanced nutrition for these preterm infants. One study demonstrated that, when compared to infants receiving standard formula, infants fed hydrolyzed protein formula had better feeding tolerance and a shorter time in achieving full feeds .Salivary and pancreatic amylases are involved in the luminal digestion of complex sugars. Digestion into oligosaccharides is then complemented by absorptive hydrolysis into monosaccharides at the epithelial brush border by enzymes that include lactase, sucrase, maltase, isomaltase, and glucoamylase. Sucrase, maltase, and isomaltase have been shown to be fully active in preterm infants. Lactase activity, which hydrolyzes lactose, which is the most abundant disaccharide, into glucose and galactose, is low in preterm infants. .Salivary amylase, which digests complex carbohydrates of 18–29 glucose units, is an initiator of carbohydrate digestion . PancreaUndigested carbohydrates pass into the distal intestine. Here, microbial fermentation results in the production of short chain fatty acids (SCFAs), which subsequently are absorbed. These can be utilized as energy sources, but butyrate has been also shown to serve as an important fuel for colonocytes as well as having properties that alter proliferation, differentiation, and turnover of colonic cells. ,28.Lactose is especially interesting from this perspective. Being the primary carbohydrate source in milk, lactose intolerance rarely occurs in the preterm population. Unabsorbed lactose conversion to SCFAs provides an efficient salvage pathway. One study suggests that lactase activity can be induced in preterm infants with enteral feedings of human milk .Most lactase activity is found at the middle to the top of the villus, while sucrase, maltase and glucoamylase are found at the mid-villus . During Insulin plays an important role in intestinal maturation and may also contribute to improve lactase activity following preterm birth. Amniotic fluid contains carbohydrates, protein, fat, electrolytes, immunoglobulins, and growth factors. Insulin is present in the amniotic fluid (up to 20 μU/mL) and after skin keratinization completed (around 26 weeks’ gestation), amniotic fluid is the main source of insulin exposure to the GI tract and plays a role in development. Preterm birth abruptly interrupts these important fetal life processes and the local insulin exposure of the GI tract with detrimental consequences .Oral insulin administration in preterm infants up to 28 days after delivery has proved effective in doubling the lactase activity .Triglycerides constitute half of the non-protein energy content in human milk and formula . The digThe absorbed free fatty acids and 2-monoglycerides are re-esterified within the epithelial cell and subsequently converted to chylomicrons, which are transported from the basal region of the epithelial cell via the thoracic duct, from which they enter the blood circulation.The digestion and absorption of medium chain triglycerides (MCTs) is less complex than that of long chain triglycerides. They do not require bile acid emulsification, are absorbed into the enterocyte without re-esterification and travel directly into the portal venous system. MCTs are frequently recommended for patients with lymphatic obstructions .Different sources of lipase include lingual, gastric, pancreatic, and epithelial cells. Human milk contains a lipase termed bile-salt stimulated lipase. After activation in the small intestine in the presence of bile acids, it facilitates long-chain triglyceride digestion. Lingual lipase is secreted from glands at the base of the tongue; its activity is lower at birth in infants at 26 weeks’ gestation, peaks at 30–32 weeks, and declines near term ,35. PancAnother limitation of fat digestion relates to bile acids, which are synthesized and excreted from the liver via the biliary system at relatively low levels in very low birth weight (VLBW) preterm infants when compared to term infants. Bile ileal reabsorption is also lower in preterm infants, which results in less efficient lipid digestion when compared to term infants ,38.Essential fatty acids cannot be produced by the body and become deficient when not supplied in adequate quantities in the diet. To prevent deficiency, adequate dietary intake of linoleic and linolenic fatty acids can prevent deficiency. Furthermore, linoleic, and linolenic acids (18-carbons chain length) undergo desaturation and elongation enzymatic processes into long-chain polyunsaturated fatty acids (LCPUFAs) with more than 20-carbons. Required for formation of eicosanoids and central nervous system structures , it is cIntestinal motility includes coordinated movements of the GI tract such as mixing, propagation of motor activities, and receptive relaxation. These movements are regulated by multiple control systems including extrinsic neurons, intrinsic neurons , interstitial cells of Cajal (ICCs), cells expressing platelet-derived growth factor receptor alpha (PDGFRα), and myogenic mechanisms, which can all operate simultaneously ,42. The The movements of the GI tract are different for each region. They also show marked differences in relation to prematurity ,44.In the literature there are several studies on GI motility in the preterm newborns compared to full term newborns, characterized by impaired gastric electrical activity and gastric emptying. Gastric motility is poorly organized in preterm infants and fundal and antral pressure waves increase with increasing gestational age (GA) ,45,46. IGastric motility is ruled by myoelectrical activity that consists of rhythmically occurring transmembrane potential variations, called slow waves, that are independent of the presence of motor activity . These wDifferent motor patterns occur in the proximal and distal stomach. In the proximal stomach, receptive relaxation and accommodation occur, which are both mediated by neurons in the brainstem via vagal reflexes. The distal stomach exhibits different motor patterns during feeding and fasting. In the feeding state, the distal stomach grinds and mixes. Extrinsic neurons are not essential for this contractile activity, but it can be modulated by vagal pathways.Intestinal motor activity is also correlated with gestational age and motor development, which is defined by phases I, II, and III of the migration of the motor complex between 37 GW and term age . In partA role of insulin on gut motility has also been supported by Shulman et al., who demonstrated significantly reduced gastric residuals within the first month in preterm infants treated with oral insulin compared to untreated peers .By 12 GW, the fetal colon has a dense neuronal network in the myenteric plexus with expression of excitatory neurotransmitter and synaptic markers. Instead, the markers of inhibitory neurotransmitters appear no earlier than 14 GW. However, electrical train stimulation of internodal strands did not evoke activity in the ENS of 12- or 14-GW tissues .Onset of evoked electrical activity in the human fetal ENS appears at approximately 16 GW. Such activity appears to coincide with increases in gene expression of various ion channels known to modulate enteric action potentials. The temporal development of several neural subtypes and enteric glia occurs between 12 and 16 GW ,54. The Studies carried out on intestinal samples of mice show that ENS originates mainly from the cells of the vagal neural crest called neural crest precursor cells (NCC) that enter the foregut at 9 embryonic days and then migrate rostro caudally and colonize the entire intestine by 14 embryonic days ,58,59.Cdh19 is a direct target of Sox10 during early sacral NCC migration towards the hindgut and forms cadherin–catenin complexes which interact with the cytoskeleton in migrating cells . The migDiverse populations of fibroblast-like interstitial cells are present in the adult gut. Loss or dysfunction of these cells has been linked to a wide variety of GI disorders. This broad group of cells comprises various subpopulations of Kit-positive ICCs and fibroblast-like cells expressing PDGFRα. ICCs located at the level of the myenteric plexus (ICC-MY) mediate slow waves, the electrical events that time the occurrence of phasic contractions ,65, whilUnlike enteric neurons and glial cells, ICCs do not arise from the neural crest, but have an embryonic development prior to the arrival of neural crest cells in the intestine. Several studies suggest that smooth muscle cells and ICCs are derived from a common mesenchymal precursor following an epithelial–mesenchymal transition process (EMT). Both ICC and CD34+ fibroblast-like cells derive from the coelomic epithelium, most likely from a common ancestor expressing the chlorine channel anoctamin-1 and smooth muscle actin alpha. Differentiation to the ICC phenotype during embryogenesis depends on cell signaling via the receptor tyrosine kinase, Kit ,67,68,69During the early postnatal period, infants undergo consistent gut development, which is parallel and interdependent, even if not always synchronous, with brain development. In the first years of life, the gut experiences huge changes of the resident microbiota and a substantial maturation of both the enterocytes and of the ENS. Meanwhile, the brain and the central nervous system (CNS) grow rapidly, both in terms of brain volume and neural function.The interdependency of the two developmental processes is mediated through the so-called gut–brain axis, which constitutes a bidirectional communication between the gut and the brain, made of several interrelated components . In receThe connection between gut and brain during early development involves both top-down and bottom-up mechanisms, with signals from the brain modulating GI functions, and GI-derived molecules influencing brain processes through different pathways. Even if the features of the MGBA in health and disease have been thoroughly described, the knowledge of the exact mechanisms through which the gut and the brain communicate in young infants is, at present, limited.The mechanisms involved in the interplay between the brain and the gut include neural, endocrine, immune, and metabolic mediators .Neural connections include the CNS, the ENS, and the autonomic nervous system (ANS). The ENS receives inputs from the brain and, in turn, provides ascending information through neural circuits. The ANS comprises sympathetic and parasympathetic nerves: the sympathetic system exerts mainly an inhibitory influence on the gut, while the vagus nerve (VN) appears to be able to sense hormones, cytokines, and metabolites from the GI tract, leading to afferent signals to the brain. The development and myelination of the VN is not complete at birth and continues until adolescence, with a peak in the myelination rate observed in the first months of life, when consumption of human milk, and human-milk-derived bioactive components, is the highest . The ANSAs for humoral components of the MGBA, they mainly consist in the hypothalamic–pituitary–adrenal axis (HPA), the enteroendocrine system and the immune system. Stress responses are modulated through the HPA, via the release of corticosterone, adrenaline, and noradrenaline. The enteroendocrine cells (EECs) in the gut produce GI hormones such as ghrelin, glucagon-like peptide (GLP-1), cholecystokinin, and peptide YY (PYY); these hormones regulate food intake and satiety and are also involved in the regulation of emotions and mood .The resident immune cells in the brain, known as the microglia, act as a neuroimmune component of the MGBA, by finely tuning neurogenesis and synaptogenesis. The maturation and function of the microglia appear to be related to changes in the gut microbiota, and also influenced by SCFAs , which aFinally, a central role in the MGBA is played by metabolic mediators, including tryptophan metabolites such as serotonin , melatonin, SCFAs, and other neurotransmitters. 5-HT is involved in most branches of the MGBA; for instance, it acts as a neurotransmitter both in the CNS and ENS, and 5-HT receptors have a critical function in the HPA . The proThere are several factors which could have a specific impact on the MGBA development in early life; one of the most relevant might be prematurity, as preterm birth interrupts the physiological growth and development of both the GI tract and the nervous system and leads to a certain degree of microbial dysbiosis. Despite that, at present there are no studies specifically designed to describe the unique features of the MGBA in preterm infants . In addiMost studies aimed at describing the developmental-related characteristics of the MGBA have been carried out using rodent models, even if gut and brain development in rodents do not exactly reproduce human developmental patterns . For thiBeyond the contribution of studies based on animal models, the plausibility of the microbiota-gut–brain interplay also during early development is supported by clinical observations: so far, a limited number of studies has shown a correlation between specific microbial features in the gut during the early postnatal period and neurodevelopment, either in term or preterm infants ,89,90,91The potential link between microbiota and neurodevelopment is particularly intriguing for preterm infants, as prematurity itself exposes them to both early dysbiosis and intrinsic risk of altered development. It has been suggested that the interplay between early dysbiosis and the gut–brain axis might lay the foundations for the altered neurodevelopment which is often observed in preterm infants experiencing necrotizing enterocolitis (NEC) . FurtherThe intestinal microbiota is important in human growth and development. The human gut is home to trillions of microbial cells that bind in a symbiotic relationship to the host playing a vital role in both health and disease ,94.The relationship between microbiome and host is dynamic and many factors  modulate the infants’ microbiome constitution and its dynamic relationship with the host, which can be transformed from ‘synbiotic’ to ‘dysbiotic’ and life-threatening ,96.Of note, as illustrated in a recent narrative review, over the past decade several studies conducted on meconium have supported the fact that the fetus could be exposed to microbiota in utero, though previously the amniotic fluid and the placenta had been thought to be sterile . PlacentAdvances in high-throughput nucleotide sequencing technologies have enhanced gut microbiota research by investigating how bacterial communities develop over time, what factors affect them, and how they affect health and disease .The microbiota performs fundamental functions in human health, especially in childhood. The first year of life is considered a crucial window for any manipulation of the intestinal microbiota in order to promote proper development of the immune system and human well-being . Human fThe TEDDY study, which describes the importance of the intestinal microbiota in the first years of life, demonstrated how the development of the microbiota in a full-term infant is influenced by breastfeeding, the type of birth, the geographical location, and the presence of siblings or animals in the home .Other studies, on the other hand, are focusing on the impact that maternal factors, antibiotic use, host genetics, ethnicity, and even COVID-19 infection can have on microbiota development ,103,104.Prematurity at birth is a determining factor in the development of the intestinal microbiota . The preSeveral studies have shown how this immaturity and diversity of the microbiota affects the development of intestinal function and anatomy of intestinal villi, crypts and of the intestinal barrier , causingHuman milk has a protective role against both NEC and LOS as it confers immunological benefits to the baby and provides nutrient-specialized microbes that likewise enrich the baby’s immune system . SpecifiThe intestine represents a vast interface between our internal and external environments. The second and third trimesters of pregnancy are crucial to the anatomical and functional development of the GI tract and the related digestive functions. Following premature birth, the immaturity of the digestive and absorptive processes and of the GI motility represent a critical challenge to the establishment of adequate enteral intakes in the preterm population and are often involved in the development of premature-related GI complications, ranging from food intolerance to NEC. In the context of gut immaturity, the choice of the optimal source of nutrition for preterm infants is fundamental: keeping mother’s own milk in mind as the magic bullet for preterm infants’ nutrition, future research should continue to address the potential role for mother’s own milk substitutes, such as donor milk and formula, for preterm infants. Specifically, the potential effects of donor milk treatments such as freezing and pasteurization on milk bioactive properties should be further investigated, while infant formula research should be oriented at developing a milk substitute which would be nutritionally adequate and, at the same time, easy to tolerate and digest for these immature infants.Moreover, there is much evidence that microbes residing in the intestinal tract play important roles in the ontogenesis of the immune system and interact with the gut and central nervous system. The interplay between GI development and microbial colonization is dual: while the immature anatomical and functional features of the preterm gut predispose to an abnormal intestinal microbial colonization, the latter may interfere with the functional, immune, and neuronal development of the GI tract. It should be constantly kept in mind that the perinatal period most likely corresponds to a critical moment in which the “set points” are impressed; it is therefore necessary to learn more about normal and healthy colonization patterns in infants to promote these patterns and avoid perturbations that result in disease throughout life.


The aim of this document is to present an overview of gene electrotransfer in ophthalmological disorders. In order to ensure an adequate variety of the assessed studies, several electronic databases were considered and studies published between January 1998 and December 2021 were analysed. Three investigators carried out data extraction and analysis, focusing on both technical  and medical  aspects and highlighting the main differences in terms of results obtained. Moreover, the IGEA experience in the project “Transposon-based, targeted ex vivo gene therapy to treat age-related macular degeneration” (TargetAMD) was reported in the results section. No clinical trial was found on international literature and on ClinicalTrials.gov. Twelve preclinical studies were found including in vivo and ex-vivo applications. The studied showed that electrotransfer could be very efficient for plasmid DNA transfection. Many attempts such as modification of the electric field, buffers and electrodes have been made and the optimization of electric field setting seems to be very important. Using this technique, gene replacement can be designed in cases of retinal inheritance or corneal disease and a wide range of human eye diseases could, in the future, benefitfrom these gene therapy technologies. The idea of gene therapy dates back more than half a century, when it was understood that nucleic acids carry genetic information .Cell electroporation or electropermeabilization generally occurs when cells either in vitro or in vivo are exposed to an external electric field. The electro gene transfer (EGT) consists in the transfer of genetic material  inside the cells through the application of electrical impulses.The electrical pulses in EGT mode perform a dual function (1). Electroporation of target cells; (2). Electrophoretic transport of genetic material across the cell membrane.Once inside the cell, the nucleic acid will give rise to one or more proteins that will produce the desired therapeutic or prophylactic effect.The main areas of application of the EGT are infectious diseases; oncological diseases; genetic diseases.The transfer efficiency of the gene material is influenced both by its characteristics  and by those of the tissue into which it is injected .Electric pulse generators can efficiently convey nucleic acids within cells allowing the user to customize the electrical protocols by varying the amplitude, duration and frequency of pulses in order to optimize the transfer of nucleic acid .With the discovery of reverse transcriptase and the advent of recombinant DNA technology, the first studies began using the simian papilloma virus SV40 to correct, in vitro, symptoms of hypoxanthine–guanine phosphoribosyltransferase (HPRT) deficiency and of adenosine deaminase deficiency severe combined immunodeficiency disease (SCID). Gene therapy consists in the transfer of genes through the use of vehicles known as vectors .Even though many studies are currently in progress, efficient gene delivery in human clinical trials remains a challenge. Nevertheless, different gene delivery systems have recently been designed and evaluated in order to treat both inherited and acquired disorders.Gene delivery can take place either ex vivo or in vivo. In ex vivo approaches, the patients’ cells are collected, cultured, modified, and transplanted back to the same individual , while iDifferent types of viral and non-viral vectors are considered, each of which has both advantages and disadvantages. Viral vectors  are the most popular system and they differ from each other for cargo limits, transfection efficiency, expression, immunogenicity, and safety profile .Non-viral delivery systems have some advantages, including a very low immunogenicity, a good safety profile and a potentially unlimited cargo capacity. They include naked DNA, physical agents like electroporation  and soniRecently, increasing attention has been paid to the applications of gene therapy in the ophthalmological field. In fact, unlike the other organs, the eye represents an immune privileged organ: (1) it is easily accessible via injections or surgically ,18; (2) The vectors can be administered by injection into the subretinal space or intravitreal . SubretiDespite different strategies being available, there are some obstacles to successfully transferring this methodology to clinical applications, due to the difficulty in entering the target cells and activating the mechanism of action for a long time without adverse effects. These limitations require both the development and the choice of appropriate vectors, a crucial point that still represents a challenge for gene therapy . ExtensiElectrotransfer (or electro gene transfer) is a recent application of the electroporation mechanism in gene therapy. Through the generation of electric fields, it is possible to increase cellular permeability (cell permeabilization) allowing the entry into the cell of proteins, vaccines, DNA and RNA molecules, otherwise poorly or non-permeable ,25,26,27Reversible electrotransfer can be used to increase the effectiveness of basic gene therapy, with applications in various fields, such as the treatment of tumors or ocular disorders. The technique is relatively easy and safe, and has been widely used in both in vitro and in vivo applications ,29,30. HIn this study, we analyzed the state of the art relating to electrotransfer applications in the ophthalmology field, in pre-clinical context, focusing in particular on the technological aspects, thus on the choice of the electrical protocol and electrodes.http://www.ncbi.nlm.nih. gov/pubmed accessed on 7 June 2022), Scopus , Web of Science  and Google Scholar (https://scholar.google.it/ accessed on 7 June 2022); clinicaltrials.gov .This review is the result of a self-study without protocol and registration number. In order to ensure an adequate variety of the assessed studies, several electronic databases were considered: PubMed  and medical  aspects and highlighting the main differences in terms of results obtained.Moreover, the IGEA experience in the project “Transposon-based, targeted ex vivo gene therapy to treat age-related macular degeneration” (TargetAMD) was reported in the results section . The proDuring the search, 14 documents found were excluded from the analysis due to: review article; electrogenetransfer in various applications outside of ophthalmological disorders . Fifteenclinicaltrial.gov (accessed on 7 June 2022). Exclusively preclinical studies were found including in vivo and ex vivo applications.Data collected from all the papers included in the analysis are summarized in Oshima et al.  were theSakamoto et al.  investigIn a study of 2002, Oshima et al.  investigElectroporation of subconjunctivally and intracorneally injected plasmids (encoding luciferase or GFP) yielded equivalent high gene expression on the entire surface of the cornea in both epithelial and stromal layers in mouse model. This relatively dispersed expression, obtained by Blair-Parks et al. , differeA significant inhibition of corneal neovascularization was reported by Yu et al.  in an alIn order to reduce the consequences of glaucoma-filtering surgery, especially changes of intraocular pressure (IOP) and bleb formation, Mamiya et al.  designedChalberg et al.  conducteHe et al.  investigTouchard et al.  have devThe electrical conditions, electrode design, plasmid formulation, method and number of injections were optimized in vivo in the rat and the rabbit models. In the rat, the electrotransfer was performed with eight square wave electrical pulses of 15 V of voltage, 20 ms of duration and of 5 Hz of frequency, while in the rabbit, eight electrical pulses of 20 V square wave voltage (20 ms duration and 5 Hz frequency) were delivered. Both the models used a platinum/iridium wire electrode inserted into the preformed corneal or transcleral tunnel as cathode, and a semi-annular platinum/iridium sheet placed on the scleral surface (in front of the active cathode) as the return anode electrode. The cathode was isolated by Teflon along its entire length, except for the terminal part, which was left naked. The two models differ in the dimensional specifications of the electrodes; indeed, in the rat model a cathode with 250 μm of diameter and a non-insulated part of 1 mm was used, while in the rabbit, the cathode had a diameter of 500 μm and a non-insulated part of about 1 cm, and the anode was approximately 2 × 0.6 cm. The results obtained demonstrated that the electrotransfer of the plasmid to the ciliary muscle with a suitable medical device represents a promising system of local and prolonged protein release for the treatment of diseases of the posterior segment, avoiding repeated intraocular injections.Kowalczuk et al.  performeIn a further study, Touchard et al.  developeIn the last included study, Touchard et al.  proposedAge-related Macular Degeneration (AMD), a neurodegenerative disease of the retina, is a major cause of blindness in elderly people . In the Even though electroporation is a standard technique in gene delivery, a modified electroporation device, cell holding cuvettes, electrodes and buffers were developed specifically for the transfection of the low cell numbers that can be isolated from the patient’s iris biopsies or pigment epithelium. Extensive in vitro and in vivo safety and efficacy studies were performed that have demonstrated that low cell numbers obtained from iris and RPE biopsies  can successfully and reproducibly transfect. Electroporation-based transfection efficiency was optimized by varying the relative amount of Sleeping Beauty transposase (SB100X) to PEDF-transposon plasmid DNA. Preliminary experiments indicate that a minimum of 5000 cells are necessary for traceable PEDF secretion after efficient transfection using electroporation. The protocol identified delivers 1 pulse with an amplitude of 200 V and a duration of 5 ms [The microcuvettes are sterile, single use, devices for GMP-grade cell product production. A V shape electroporation chamber was adopted to facilitate the cell recovery after transfection. The chamber has 5 mm aperture and 5 mm height with a distance of 2 mm between the electrodes , defininThis shape of the electroporation chamber ensures two different advantages: (1) a lower current density, because the area of the electrodes is bigger when compared to the overall transfection volume; (2) a lower voltage applied to the electrodes, because the electric field distribution and value depend on the distance between the electrodes; (3) to facilitate the cell recovery after transfection.The overall results aim at optimizing the transfection process in terms of efficiency, i.e., % of transfected cells, and cell viability. To ensure the maximum biocompatibility of the cuvette, the electrodes of the final device, made of stainless steel, have been gold plated with a minimum gold thickness of 1 μm. Since the gold cannot be plated directly on the steel, a thin layer of nickel makes the interface between the two metals. Although the nickel has a low diffusion speed, creating a barrier to the diffusion of the other atoms composing the stainless steel, it might introduce biocompatibility questions. However, the limited contact time and the final product qualification according to ISO 10993-1 mitigate the risk of metals release into the tissue, ensuring biological safety. The final cuvette  was prodThe electroporator and the electroporation cuvettes developed for the electroporation of small volume cell samples was effective to transfect the isolated and transfected iris pigment epithelial (IPE) cells with a plasmid mixture .The efficacy of the TargetAMD approach was validated under clinical trial conditions. Using GMP-grade plasmids, buffer, the microcuvette and the electroporator, rat retinal pigment epithelium (RPE) and iris pigment epithelium (IPE) cells were successfully transfected with the human PEDF gene and subretinal transplantation of the transfected cells resulted in significantly reduced Choroidal neovascularization (CNV) in a rat model of laser-induced CNV. The performance of the electroporator and electroporation cuvettes was assessed by the consortium of TargetAMD that successfully have qualified the performance of the new device with 100% reliability.In the early 1990s, different electrotransfer protocols were developed to overcome both the potential risks of currently available viral gene delivery systems and the low efficiency of existing non-viral systems ,52,53,54The suitability of skeletal muscle cells to electrotransfer procedures is mostly due to their size, shape, and morphology ; electroPre-treatment of the targeted muscle with hyaluronidase increases the ratio of electrotransferred muscle fibres while reducing the need for high electric voltage, hence decreasing the risk of muscle damage .Electroporation parameters  need to be specifically adapted to tissue in order to obtain optimal gene transfer. Currently, in the majority of research, a pattern for in vivo electroporation averaging 610 pulses of 20–40 ms at 1 Hz with field strength on the order of 100–200 V/cm is used . ShorterThe instrumentation required for electroporation consists of a pulse generator and an “applicator”, which includes the electrodes. The electrodes geometry determines the strength, homogeneity, orientation, and shape of the electrical field, as well as the current flow and the total energy transferred to the target tissue during electroporation. Different electrodes have been developed: surface electrodes, fixed electrodes for sub-cutaneous tissue, needle electrodes for deep tissues, and electroporation catheters for hollow organs.Despite the many benefits of non-viral gene delivery, including increased safety, decreased toxicity, decreased cost, and large transgene size capability, interest in non-viral gene therapy was limited until a few years ago, in part due to transient gene expression. In fact, the efficiency of delivering remains one of the most challenge on non-viral therapy. It seems clear that, if vector shows a good efficiency, its toxicological profile increases and, on the contrary, a good toxicological profile corresponds to low efficiency. Anatomic barriers like epithelial, endothelial cells and extracellular matrix contribute to reducing the efficiency of these methods . PhysicaEyes are immune privileged organs that have a great potential for gene therapy due to their accessibility, presence of a tight ocular barrier that prevents spread to other organs and allow to easily verifying the structure and anatomy with non-invasive methods ,18,19.Advances in molecular biology have led to the identification and characterization of the genetic disorders responsible for many eye diseases. This has led to the development of genetic tools aimed at inducing, regulating or repairing gene expression. Most of the molecules used for these purposes are synthetic nucleic acids such as plasmids, ribozymes, siRNAs and oligonucleotides. The therapeutic efficacy of these molecules depends on the selection of suitable vectors and the efficient delivery of the system to target cells for their appropriation of expression in vivo. This approach can be used, if necessary, for both specific inhibition and induction of protein expression in target cells.During the last decade, several authors have demonstrated the potential benefits of electrical fields (electroporation and iontophoresis) to enhance gene delivery and improve cell and tissue targeting.Some studied showed that low-voltage electric pulses successfully transfer the gene of interest to highly selective areas of the corneal endothelium without inducing any pathological changes. These authors surmised that improved versions of this highly targeted technique would allow effective gene transfer to other intraocular tissues such as retina ,43,44,45These studies have confirmed the promising potential of powerful non-viral physical methods to increase nucleic acid release in ocular tissues. These methods can potentially also provide a means for specific aiming of multiple eyepieces fabrics using custom designed plasmids or oligonucleotides.Electrotransfer is very efficient for plasmid DNA transfection. Many attempts such as modification of electric field, buffers and electrodes have been made and the optimization of electric fields setting seems to be very important . Many tyAim of the project TargetAMD was to introduce a novel gene therapeutic treatment that will be effective, safe and lasting for the life of the patient. TargetAMD will use subretinal transplantation of genetically modified RPE or iris pigment epithelial (IPE) cells genetically modified to overexpress the anti-angiogenic and neuroprotective factor pigment epithelium. The success of the gene therapeutic treatment proposed in TargetAMD rests on the use of the non-viral, hyperactive Sleeping Beauty (SB100X) transposon system to deliver the PEDF gene to RPE and IPE cells. The PEDF-transfected cells will then be transplanted to the subretinal space of AMD patients.Therefore, although the basic instrumentation and its long-term application, the modalities of safety and efficacy, as well as the side effects of electrically assisted ocular gene therapy have been defined, clinical trial shall be planned and conducted in order to assess feasibility and efficacy of electrically assisted ocular gene therapy in clinical practice. Two phase Ib/IIa clinical trials  will be performed, one trial in which PEDF-transfected autologous IPE cells  and one in which autologous RPE cell transfected with the PEDF gene  will be transplanted subretinally in neovascular AMD patients. The comparison of study results could show if the use of easier to transfect, but more invasive RPE cells is superior to the use of easy to biopsy IPE cells, which presents a significantly lower risk for the patient.Electrotransfer is very efficient for transfection of plasmid DNA and using this technique, gene replacement can be designed in cases of retinal inheritance or corneal disease. Therefore, a wide range of human eye diseases could, in the future, benefit from these gene therapy technologies.


Friedreich’s ataxia (FRDA) is a rare genetic disorder caused by mutations in the gene frataxin, encoding for a mitochondrial protein involved in iron handling and in the biogenesis of iron−sulphur clusters, and leading to progressive nervous system damage. Although the overt manifestations of FRDA in the nervous system are mainly observed in the neurons, alterations in non-neuronal cells may also contribute to the pathogenesis of the disease, as recently suggested for other neurodegenerative disorders. In FRDA, the involvement of glial cells can be ascribed to direct effects caused by frataxin loss, eliciting different aberrant mechanisms. Iron accumulation, mitochondria dysfunction, and reactive species overproduction, mechanisms identified as etiopathogenic in neurons in FRDA, can similarly affect glial cells, leading them to assume phenotypes that can concur to and exacerbate neuron loss. Recent findings obtained in FRDA patients and cellular and animal models of the disease have suggested that neuroinflammation can accompany and contribute to the neuropathology. In this review article, we discuss evidence about the involvement of neuroinflammatory-related mechanisms in models of FRDA and provide clues for the modulation of glial-related mechanisms as a possible strategy to improve disease features. FXN), which is located in the centromeric region of chromosome 9q. When the most common mutation, which consists of the expansion of GAA repeats in the first FXN intron, is present in homozygosis, it leads to the decreased transcription of FXN, with pathologic loss of the protein function. The severity of the disease depends on the number of repeats, and it can be associated with progressive ataxia, weakness, and sensory deficits, with symptom onset usually occurring in childhood or adolescence. Patients often die of cardiomyopathy. The disease has an incidence of one case in 50,000 individuals in the Caucasian population, and represents the most common of the hereditary ataxias [Friedreich’s ataxia (FRDA) is a recessive genetic disorder involving mainly the nervous system, caused by mutations in the gene frataxin  clusters, thereby affecting electron transport chain activities and several metabolic, DNA repair, and ribosome biogenesis enzymes [ enzymes . Consequ enzymes ,4, and i enzymes ,6. Princ enzymes . Even th enzymes .Moreover, although the pathological manifestations of FRDA are primarily observed in the neurons of both the central and peripheral nervous system, it is emerging that the surrounding non-neuronal cells may also contribute to the pathogenesis of the disease, as demonstrated for other neurodegenerative disorders . The invThis review will present the contribution of neuroinflammation to the FRDA pathology and will discuss how modulating this mechanism could be a valuable means to modify pathological phenotypes.In recent years, neuroinflammation in neurodegenerative disorders has been assumed to be of great importance, and iron accumulation has been identified as a significant driver of cell reactivity in the brain . NervousNeuroinflammation often precedes and worsens overt neuron death. In different neurodegenerative conditions with a robust neuroinflammatory component, contrasting neuroinflammation has been proven to be one of the most efficient ways to slow down disease progression . The micAstrocytes constitute the scaffold of the entire CNS, and their processes participate in the neurovascular unit of the blood−brain barrier (BBB). Their functions range from regulating cerebral blood flow, to maintaining water, small molecules, and neurotransmitter homeostasis, forming synapses, and supporting neuron metabolism. Like microglia, astrocytes respond to insults through reactive astrogliosis that, if sustained, can result in the formation of a glial scar as part of the neuroinflammatory process . BecauseTherefore, iron accumulation, mitochondria dysfunction, and ROS production, which are mechanisms identified as etiopathogenic in neurons in FRDA , can simSpecific pathways related to neuroinflammation are altered in the microglia, astrocytes, and myelinating glial cells in FRDA, as shown in The first study describing glial activation in the brain of FRDA patients was reported by Koeppen et al., who observed a loss of juxtaneuronal ferritin-containing oligodendroglia and a prominent ferritin immunoreactivity in microglia and astrocytes in the dentate nucleus of patients with FRDA. These features were accompanied by neuronal atrophy and a so-called grumose degeneration, an unusual proliferation of synaptic terminals in the dentate nucleus. This degeneration indicated mitochondrial iron dysmetabolism in the terminals of corticonuclear fibers . In addiThe role of microglia activation in FRDA has been described in the KIKO mouse model of the disease, where the intracerebroventricular injection of the inflammatory stimulus lipopolysaccharide (LPS) induced a greater microglial activation compared with the healthy mice. The swollen cell bodies had shortened processes, suggested that the microglia in FRDA mice are in a more activated state than the microglia in wild-type mice. Furthermore, the authors observed an increase in oxidative damage and the DNA repair proteins MUTYH and PARP-1 in the cerebellar microglia of FRDA mice. These aberrant features were attenuated through the administration of PJ34, a PARP-1 inhibitor, suggesting that microglial PARP-1 could be an important therapeutic target in FRDA. The involvement of DNA damage in the activation of FXN-deficient microglia was further confirmed in experiments in vitro on microglial cell lines, where the knockdown of FXN increased DNA damage and the expression of the DNA repair genes MUTYH and PARP-1 .In other mouse model of FRDA, YG8R, the transplantation of wild-type mouse hematopoietic stem and progenitor cells (HSPCs), resulted in the amelioration of muscle weakness and locomotor deficits . In the Astrocytes play crucial roles in the pathogenesis of several forms of ataxias, where they contribute to disease progression in a phase-specific manner and represent a new target for therapeutic approaches . In cereLoss of FXN is detrimental not only to neurons, but also to the normal function of astroglia; cerebellar astrocytes may contribute to FRDA clinical symptoms, showing specific vulnerability to FXN deficiency . In humaIn accordance, the astrocytes differentiated from neural stem cells obtained from the YG8R model exhibited detrimental signs, such as the reduced activity of the Fe-S containing enzyme aconitase . AlteratSustaining a non-cell-autonomous toxic effect of FXN in vivo, the ablation of FXN in astrocytes during development in FGKO mice (where FXN is ablated in a time-dependent manner) caused severe ataxia and early death, inducing growth and survival impairments. In contrast, the mice in which FXN was knocked out in astrocytes later in life did not give rise to apparent neurological phenotypes, indicating that developing cerebellar astrocytes are more vulnerable to the lack of FXN, and suggesting a role of astrocytes in the progression of the disease . ExtensiTargeting astrocytes in models of the disease represents a promising strategy. Indeed, in FGKO and YG8R mice, treatment with insulin-like growth factor I (IGF-I), previously shown to normalize FXN levels in FXN-deficient neurons and astrocyte cultures through the Akt/mTOR signaling pathway , proved In addition, in YG8R mice, treatment with granulocyte-colony stimulating factor (G-CSF) and stem cell factor (SCF) markedly reduced the extent of astrocytosis and inflammatory cell infiltration within the dorsal columns, spinocerebellar, and corticospinal tracts. The results indicate that attenuating neuroinflammation slows down the progression of the disease. The neuroprotective action of this combined treatment was indeed exerted at a clinical level, resulting in a significant improvement in motor coordination and locomotor activity, even after the onset of neurological symptoms .It has recently been demonstrated that targeting Sonic Hedgehog (SHH) with the Smoothened antagonist (SAG) rescued mitochondrial dysfunction and reverted the neurotoxicity induced by the lack of FXN in human astrocytes in vitro, showing the potential of pharmacologically targeting astrocytes cells to attenuate neurodegeneration in FRDA .In Drosophila melanogaster, FXN knockdown in the glia affects fly locomotion, increases brain vacuolization due to cellular degeneration, and induces defects in lipid metabolism and oxidative stress , suggestOverall, these results demonstrate that astrocyte activation could exacerbate or even cause neuronal dysfunctions, triggering a further amplification of astrogliosis in a detrimental vicious circle.Finally, myelinating glial cells are also implicated in FRDA, with oligodendroglia and Schwann cells being highly susceptible to FXN deficiency. In the dentate nucleus of FRDA patients, ferritin is expressed mainly in the oligodendrocytes, while, as the disease progresses and neurons begin to undergo atrophy, these cells disappear, being replaced by positive ferritin microglia . As demoAltogether, this evidence suggests that the expression of mutant FXN in glial cells may act as a trigger, responsible for their reprogramming and functional impairment, contributing to the degeneration of nearby neurons.FRDA is a chronic, progressive, and frequently life-threatening neuromuscular disease. Like all rare diseases, it has a high impact on the quality of life of patients and their families, accompanied by the lack of public awareness.Unfortunately, ataxia has no cure, and the current therapies are aimed at motor re-education or muscular reinforcement. Several potential treatments have been subjected to clinical trials or are being developed for human studies, and include strategies that increase FXN levels, protein and gene replacement therapies, antioxidants, iron chelators, and modulators of inflammation . The absAmong these mechanisms, the contribution of neuroinflammation to the pathology has been largely neglected, possibly missing out on relevant diagnostic, prognostic, and therapeutic targets of the disease. Recent findings suggest that the inflammatory response in the cerebellum and spinal cord may be a critical mechanism in the pathogenesis of FRDA, and that modulating neuroinflammation could be a possible strategy for the control of the disease.The studies discussed in this review support a strong involvement of the neuroinflammatory mechanisms in FRDA, which has both pathomechanistic and therapeutic implications . StudiesIn conclusion, we believe that investigating the role of neuroinflammation is fundamental for the comprehension and manipulation of the progression of FRDA. Glia targeting could play a valuable role in ameliorating neuronal circuits in FRDA-affected CNS regions, consistently with other neurodegenerative conditions, where the modulation of inflammation represents one of the most promising therapeutic strategies.