Electroconvulsive therapy (ECT), the oldest somatic therapy still in use in psychiatry today, remains one of the most effective therapeutic interventions for a wide variety of psychiatric disorders. In this article, we review some of the recent advances in ECT that are currently being researched and implemented in clinical practice. We explore recent studies that point to the potential therapeutic benefit and safety of ECT in COVID-19-related neuropsychiatric complications and special populations (such as the elderly and pregnant persons) that are generally at higher risk of having adverse effects from psychotropic medications. We highlight studies that performed a head-to-head comparison of ECT and ketamine, which has shown promise for treatment-resistant depression and acute suicidality. Researchers continue to explore different ways of using ECT by modifying the treatment parameters to maintain efficacy and decrease side effects. Neurocognitive side effects remain one of the major drawbacks to its use and contribute to the negative stigma of this highly effective treatment. In this regard, we describe attempts to improve the safety of ECT by modifying dosing parameters, novel electrode placements, and the addition of augmenting agents with the aim of decreasing side effects and improving efficacy. This review identifies some of the recent advances in the last few years in ECT research while also highlighting areas where further research is needed. Early case reports and observational studies on ECT showed good efficacy in treating severe mental illness, and it quickly made its way into Europe and the United States, replacing chemically induced convulsive therapies that were in use at the time2. Due to concerns related to mechanical injuries from motor convulsions, the treatment was refined in the 1950s by the addition of a muscle relaxant and an anesthetic agent to reduce tissue injury1. This led to a significant decrease in the prevalence of this complication associated with ECT3. Since its invention and first use in 1938 by Italian psychiatrists Ugo Cerletti and Lucio Bini5. Later, the D’Elia placement came to be accepted as the standard right unilateral (RUL) placement7, yet, cognitive SEs still persist8. Importantly, we still have not fully characterized the mechanisms of action and SEs of ECT. Studies have investigated numerous potential therapeutic mechanisms including increased neurogenesis, monoaminergic neurotransmission, activation of the immune system and neuroendocrine activation9. Despite its efficacy in the rapid treatment of multiple psychiatric disorders and symptoms, ECT remains an unpopular, stigmatized psychiatric treatment, partly due to its cognitive side effects (SEs), including anterograde and retrograde amnesia. Psychiatrists Lancaster, Steinert and Frost introduced the non-dominant hemisphere unilateral electrode placement method that has a superior SE profile compared to the conventional bitemporal (BT) placementIn this article, we will explore recent advancements in research within the last three years that aim to reduce cognitive SEs of ECT and review studies that attempt to compare ECT with newer treatment modalities. We will also review recent research that explores the following areas: a) potential novel indications for ECT; b) combination of ECT with other treatment modalities; and c) optimization of dosing and administration.12. Most recently, Tang et al. randomized 25 female patients with comorbid depression and PTSD to ECT paired with pre-treatment traumatic memory reactivation and ECT paired with pre-treatment non-traumatic memory reactivation. The authors hypothesized that ECT will decrease traumatic memory after reactivation of the traumatic memory. The results showed no difference in the two treatment groups in both the Modified PTSD Symptom Scale Self Report (MPSS-SR) and the Clinician-Administered PTSD Scale for DSM-5 (CAPS-5) measured immediately post-ECT treatment course and at 3 months follow-up. Importantly, however, both groups had an approximately 35% decrease in MPSS-SR score and a 37% decrease in CAP-5 score at 3 months follow-up. A significant drawback in this study was the inability to assess the moderating effect of improvement in depression scores due to insufficient data10.In addition to its common indication in patients with severe treatment-resistant major depression, bipolar disorder, schizophrenia and catatonia, researchers continue to explore the use of ECT in other psychiatric disorders. Researchers have explored the amnestic SE of ECT as a possible therapeutic effect in patients with post-traumatic stress disorder (PTSD) by attempting to disrupt the reconsolidation of traumatic memories13. A recent pilot study randomly assigned seven patients diagnosed with depression and comorbid PTSD to receive either low amplitude seizure therapy (LAP-ST), an ECT protocol that has been found to have fewer cognitive SEs, or right unilateral (RUL) ECT13. All patients had an improvement in PTSD Checklist (PCL) scores with a mean change in PCL score from 42.5 to 31 in the LAP-ST group and 64.7 to 41 in the RUL group. Future studies are needed to replicate these findings using larger samples and a longer follow-up time to determine long-lasting effects of ECT in patients with PTSD.Some authors have theorized that the improvement in PTSD symptoms after ECT could be due to increased cognitive and adaptive function as a result of increased neuroplasticity and synaptogenesis rather than amnestic SEs14. The Prolonging Remission in Depressed Elderly (PRIDE) study15 examined whether a novel continuation algorithm of ECT plus medication (venlafaxine + lithium) was associated with a better relapse rate and SE profile compared with medication only (venlafaxine + lithium) among elderly patients >60 years of age with major depressive disorder (MDD) who achieved remission after an acute course of RUL ultra-brief (RUL-UB) ECT with venlafaxine. The study developed a novel individualized ECT algorithm for the continuation phase comprising once-weekly ECT treatment for 4 weeks and a subsequent treatment (5–24 weeks) schedule that was based on patients’ Hamilton Depression Rating Scale (HDRS) scores. Patients who received continuation ECT + medication had a better HDRS score at the end of the 24-week follow-up compared to the medication-only group15. In addition, most of the neurocognitive SEs, such as deficits in short and long-term memory, cognitive flexibility, phonemic fluency and recognition of learned words, that developed in both treatment groups were short-lived with most patients returning to baseline within 1–6 months and there was no statistically significant difference on the mini-mental state examination16. In a secondary analysis, the authors also found RUL-UB ECT to be very effective with a 75% remission rate in elderly patients with moderately severe MDD, a sub-population that has not been investigated extensively for ECT response17.Researchers are continuing to explore the safety and use of ECT among the vulnerable elderly population18 found an improvement in both psychiatric and motor symptoms of Parkinson’s disease post-ECT. Similarly, another study of 15 patients with Parkinson’s disease with psychiatric symptoms reported improvement in mentation, behavior, mood, performance of daily activities, motor status and psychiatric symptoms at the end of 12 sessions of ECT and at 1-month follow-up19.ECT has been investigated in the management of Parkinson’s disease with psychiatric manifestation and/or comorbid psychiatric conditions, especially since anti-psychotics and anti-parkinsonian medications could worsen parkinsonian symptoms and psychotic symptoms respectively. A study of 12 patients with Parkinson’s disease and comorbid psychiatric illnesses including depression, hallucinations, delusions and impulse control disorder20. Evidence from case reports and case series have reported changes in fetal heart rate (FHR) activity associated with ECT and guidelines have generally advised auscultation of FHR for pregnancies <24 weeks and non-stress tests (continuous FHR) for pregnancies >24 weeks, pre- and post-ECT, respectively21. A recent study performed continuous FHR during and for 10 minutes following ECT treatment in five women with severe mood disorder during their course of ECT treatment22. A total of 34 fetal monitoring recordings were obtained in 44 ECT sessions and only four were associated with FHR decelerations (decreased heart rate > 30 bpm) with none of the recordings having a nadir below 90 bpm. The decelerations resolved spontaneously within 4 minutes and the study did not have any negative fetal outcomes. This study, though small in size, provides supporting evidence for the safety of ECT, particularly in pregnant women with very severe mood and psychotic illnesses that may not be amenable to pharmacotherapy. In such cases, ECT may be a safe treatment alternative.ECT has long been a treatment option during pregnancy, especially when there is no safer treatment; however, its use remains limited, partly due to the lack of studies that establish safety and provide accurate guidelines that would ensure fetal well-being23. A second report was that of a 25-year-old who developed a first manic episode with psychosis following COVID-19 infection that was equally resistant to medications but responded well to ECT24. Two more COVID-19-related treatment-resistant neuropsychiatric complications both in individuals in their 50s who responded to ECT were reported: a case of malignant catatonia, and the second a case of psychosis and suicidality26. In some of these cases, there was a notable increase in levels of acute phase reactants, CSF protein and IgG, suggesting a possible immune-mediated mechanism. As the COVID-19 pandemic continues, it is important for clinicians to be aware of the role of ECT as an option for treatment-resistant neuropsychiatric complications associated with COVID-19.Although there were reductions in ECT utilization during the COVID-19 pandemic, it was found useful as a treatment modality in a few cases of new-onset COVID-19-related neuropsychiatric complications. A 51-year-old woman who developed her first episode of depression, psychosis and catatonia following COVID-19 infection had full symptom remission with ECT, after non-response to trials with multiple medications including olanzapine, risperidone, aripiprazole, sertraline and escitalopram27. Ketamine acts on the glutamate receptor, specifically as an N-methyl-D-aspartate (NMDA) receptor antagonist27. Few randomized clinical studies have conducted a head-to-head comparison between ketamine and ECT. Thirty-two patients aged 18 – 59 years old were randomized to receive either twice-weekly IV ketamine infusion or BT-ECT until remission28 in a study that reported a more rapid improvement in depression scores in the ketamine treatment arm compared to the ECT treatment arm; however, the effect of ketamine appeared to wear off after about a month of treatment and HDRS score almost returned to baseline by the third month post-treatment. The ECT group, on the other hand, appeared to have a longer-lasting treatment response even at 3 months follow-up and there was no significant difference in cognitive SE between the two treatment groups. The study was limited by a small sample size and it was unclear what severity of depression was used to determine study inclusion and also how long the patients received either treatment. A similar faster antidepressant effect of ketamine compared to ECT was also reported by Basso et al. and they additionally found that patients on ketamine had significantly greater improvement in neurocognitive domains of attention and executive function compared to the ECT group, and that verbal memory was significantly lower in the ECT compared to the ketamine group29. The study had a very limited follow-up period and hence did not assess whether the antidepressant response was sustainable. Ketamine is emerging as a desirable treatment for treatment-resistant depression (TRD) among many patients since it has fewer cognitive SEs than ECT, and has a rapid onset of action like ECT30. More patients in the ECT group achieved remission compared to the ketamine group31. However, younger patients were noted to have an equally favorable response to ketamine and ECT while older patients responded more favorably to ECT.There may exist an age difference in the treatment effect of ketamine compared to ECT. A much larger study, KetECT, randomized 186 patients with depression to thrice-weekly racemic ketamine or ECTet al. explored the role of ECT and ketamine in the treatment of suicidality32 by randomizing 45 patients to receive ECT, oral ketamine or intramuscular ketamine, and assessing their depressive and suicidal symptoms using HDRS and BSI at baseline, weekly during the study, and at 1-week and 1-month post-treatment. All three groups had a significant decrease in HDRS and Brief Symptom Inventory (BSI) scores compared to baseline at the end of treatment; however, there was a significant difference in suicidality scores on the BSI in the ketamine treatment groups on day 2 and week 2 of treatment compared to the ECT group. There was no significant difference in the antidepressant effects in the three treatment groups at the end of 1-month follow-up. All the randomized controlled trials (RCTs) discussed above were limited by a small sample size and a short follow-up period. Two larger studies with longer follow-up periods are underway that hope to address these limitations and would provide additional data on the benefits of ketamine versus ECT for maintenance treatment34. Pooling the available studies, a recent systematic review and meta-analysis found ECT to be more effective than ketamine, and that each intervention had a distinct set of adverse events35.Kheirabadi 36; however, most of these adverse effects resolved within 6 months16. Both pharmacological and non-pharmacological interventions have been employed to remediate these adverse effects. A study did not find a clinically significant difference in recall memory and on the mean total scores of the MMSE in patients treated with memantine 5 mg/day vs melatonin 3 mg/day during the first six sessions of ECT treatment37. Similarly, donepezil was not found to improve cognitive performance in an RCT that compared donepezil to placebo39. However, a recent meta-analysis found statistically significant improvement in cognitive function with memantine and liothyronine with moderate to large effect sizes, but the quality of the evidence was generally poor due to insufficient number of studies, small sample size, differences in study methodology and risk of bias40. The negative outcomes of these studies may be because a different mechanism, not addressed by these drugs, may underlie the cognitive impairment associated with ECT. An RCT is underway to explore the utility of cognitive control therapy to improve performance by enhancing working memory and cognitive control processes in patients undergoing ECT41.There have been attempts to mitigate the adverse effects of ECT, especially the neurocognitive SEs of ECT. The PRIDE study found a significant decline in cognitive function in several cognitive domains following RUL ultrabrief pulse ECT treatment in geriatric patients with TRD43. However, certain drugs that may be co-administered during ECT, such as labetalol and atropine, may hinder the hemodynamic benefits associated with the use of dexmedetomidine45 and thus caution is warranted in the use of these medications. Despite the potential benefits associated with dexmedetomidine, some authors have noted that it may lower seizure duration, which could affect the quality of ECT43.ECT produces a robust hemodynamic response comprising an acute parasympathetic surge, which causes bradycardia followed by a sympathetic surge, which leads to tachycardia and hypertension. Recent studies have explored the role of the α2-adrenergic agonist, dexmedetomidine, in reducing the autonomic response associated with ECT. Two clinical trials have recently reported better hemodynamic response, including lower heart rate, systolic and diastolic blood pressure, mean arterial blood pressure and lower incidence of postictal confusion in patients who were pretreated with dexmedetomidine prior to ECT- other anesthetic agents versus ECT + other anesthetic agents only46 and there was no benefit with ketamine either alone or in combination with other anesthetic drugs. Patients who received ketamine only with ECT were also more likely to have higher blood pressure. The study found no difference between the groups in terms of study discontinuation, recovery time and observed seizure activity. Another meta-analysis that pooled data from 18 RCTs found similar results, with the additional findings of increased EEG seizure duration and reduced ECT dose in patients who received ketamine47. Though no difference was found in efficacy and adverse effects in these studies, the potential for ketamine to reduce the dose of ECT may be worth further investigation as a mitigation strategy to reduce overall ECT adverse effects.Studies have reported mixed results regarding the potential benefit of augmenting ECT by adding ketamine as an anesthetic agent by itself or with other anesthetic drugs. A recent meta-analysis pooled data from 17 RCTs that compared ECT + ketamine +/48. Buday et al. found that this strategy resulted in a significantly lower seizure threshold after administering TMS over the dorsolateral prefrontal cortex (DLPFC) 30–80 minutes prior to ECT treatment48. Similarly, Rothermel et al. found a significantly greater percentage improvement on the HDRS and that a lower electrical charge was needed for stimulation using this method compared to standard ECT49. There was no significant difference in cognitive SEs between treatment groups. The ideal TMS parameters and interval between TMS and ECT treatment needed to produce an optimal decrease in seizure threshold remains unclear.ECT augmentation with interventions such as hyperventilation, use of remifentanil, or even sleep deprivation to lower seizure threshold or increase seizure duration has been explored with the idea that longer seizure duration is associated with superior clinical outcome. TMS applied prior to ECT has been explored as a potential modality of reducing seizure threshold in patients undergoing ECT because of its potential to increase cortical excitability50. The total charge, pulse width, frequency, train duration and current amplitude all contribute to treatment response, electric field intensity and seizure induction with ECT52. One area of research has focused on modification of stimulus pulse width to enhance efficacy and reduce cognitive SEs of ECT. Ultrabrief pulse (<0.3 ms) has become popular in clinical practice today due to the evidence for its superior cognitive SEs in RUL ECT. Less is known, however, about its potential benefit with other electrode placements. Two randomized clinical trials have explored its benefit for bitemporal ECT. Results suggest that ultrabrief pulse ECT provides a better cognitive SE profile than brief pulse (1–2 ms) ECT54. Studies have also indicated a longer treatment course may be needed to achieve remission with ultrabrief pulse ECT55.The strength of the electric field induced by conventional ECT is above the excitation threshold of most neuronal tissue in the brain, resulting in activation of almost the entire brain, which may contribute to cognitive SEset al. (2011) reported on a case series of five patients successfully treated with 500 mA current56. Subsequently, a small pilot study randomized seven patients with depression and active suicidality to low amplitude ECT  versus standard RUL ECT  and all patients achieved remission in suicidal ideation regardless of their treatment group57. However, the study was limited by small sample size and absence of data regarding cognitive SEs. Abbott et al. (2021) published a larger, well-designed, randomized controlled trial of 60 patients who were randomly assigned to receive ECT at 600, 700, or 800 mA58. They found that currents lower than 800 mA had less of an adverse impact on verbal fluency, but the higher currents were associated with better depression outcomes58.The amplitude of the pulse has also been an area of research interest. While older studies from the 1940s and 1950s reported on using low current amplitudes to induce seizures, modern studies had left the current amplitude parameter of ECT dosing relatively unexplored until Rosa 60. iLAST is based on the hypothesis that the seizure drives efficacy while the electrical current drives cognitive SEs.The results from these studies indicate that lowering the amplitude of seizure therapy may be a viable option with a suggestion of superior cognitive outcomes, but more studies are needed to confirm these preliminary findings and to identify how to individualize dosing to optimize outcomes. A novel approach to individualizing amplitude is individualized low-amplitude seizure therapy (iLAST), an experimental dosing strategy that aims to deliver an individually titrated current amplitude as a means of achieving therapeutic seizures with a minimal amount of electrical current induced in the brain61. A randomized cross-over clinical trial that assigned nine participants with TRD to four treatment groups of brief vs ultrabrief and RUL temporoparietal (TP) vs RUL frontoparietal (FP) electrode placements found no superiority of FP over TP placement, but patients who received ultrabrief pulse were found to have better visual memory compared to those who received brief pulse ECT62.Apart from pulse width and amplitude, spatial position and orientation of the electrodes are equally important contributors to efficacy and adverse effects. BT, RUL and bifrontal (BF) are the three conventional electrode placements commonly used clinically, with the latter two having superior SE profile compared to BT placement. Electrode placements over the temporo-parietal, frontoparietal and supraorbitoparietal regions may have therapeutic advantage over the RUL electrode placement, which remains to be confirmed in more rigorous experimental studies63. Two recent open-label nonrandomized studies, one that assessed cognitive SEs and antidepressant efficacy and a second that looked at the anti-suicidal efficacy of FEAST compared to standard RUL ECT, found similar efficacy and adverse effect profile with slightly better nonsignificant difference in cognitive adverse effect in the FEAST group65.Further efforts to enhance control over the electrical stimulation site and distribution of electric field in the brain, such as Focal Electrically-Administered Seizure Therapy (FEAST), use specially shaped electrodes that are placed asymmetrically to enhance focal stimulation over the fronto-orbital cortex66. MST leverages the focality of TMS  to spare regions of the brain driving cognitive SEs, and couples that with the powerful therapeutic efficacy of seizures. Several clinical studies have compared the efficacy and SE profile of ECT and MST with results showing similar efficacy and better cognitive SE profile with MST69. More recently, a relatively larger effectiveness study was conducted comparing MST to BT-ECT and RUL-ECT70. Patients in the MST group had significantly greater improvement in HDRS-21 score compared to those who received RUL-ECT but not BT-ECT, and time to orientation was significantly shorter in those who received MST compared to ECT treatment groups. Cognitive SEs as measured 4-hours post-session with Wisconsin Card Sorting test and Weschler memory scale-revised favored MST over ECT, but there were no data to determine if these effects were sustainable. Another non-inferiority randomized double blind study is currently underway to compare the efficacy and tolerability of MST compared to RUL-ECT in patients with treatment-resistant depression71.Alternatively, magnetic seizure therapy (MST) uses high doses of TMS, given under anesthesia, to induce therapeutic seizures72. A randomized clinical trial of transcranial electric stimulation therapy (TEST), which is identical to NET, is underway and aims to deliver low-charge, high-amplitude electrical stimulation by decreasing the frequency and train duration using bifrontal electrodes. Li et al. employed a similar technique but termed it low-charge electrotherapy (LCE), where they randomized patients with schizophrenia to receive LCE or standard BT ECT and both groups experienced a significant improvement in Positive and Negative Syndrome Scale (PANSS) score73. However, there were significantly lower overall SEs reported in the LCE group. On the other hand, response was slower in the LCE group, and the patients required more treatment sessions. The same group conducted a follow-up RCT study (Hybrid-ECT) by providing the benefits of early remission through initial treatment with standard bitemporal ECT up to four sessions followed by LCE sessions74. This study also found comparable improvement in PANNS score between the two groups, but fewer overall SEs and an increased number of treatments in the hybrid-ECT group. Findings from the TEST study would further shed light regarding the therapeutic necessity of a seizure with ECT-like stimulation and may establish the associations between seizure, electrical field magnitude, efficacy and cognitive SEs.Researchers are challenging the long-held notion that a seizure is required for the antidepressant effect of ECT. Evidence from an open label pilot study in 11 TRD patients who received thrice weekly nonconvulsive electrotherapy (NET) below the seizure threshold were reported to have response and remission rates that were comparable to standard ECT75 and The Global ECT-MRI Research Collaboration (GEMRIC)76 may provide the data needed for further research in these areas. ECT remains one of the most effective and relatively safe treatments in psychiatry. It is a safe treatment in the elderly population with severe and moderately severe depression, as well as pregnant individuals. However, while there have been positive developments in reducing cognitive SEs with ECT, these SEs still pose a significant barrier to broader utilization. Promising approaches to improve the risk/benefit ratio of ECT include optimization of stimulation parameters and electrode configuration. Investigational interventions such as MST and TEST will help advance our understanding of whether it is the seizure or the electric field that is driving the antidepressant effects of ECT. Further research will be needed to identify who is most likely to benefit from ECT, so that they might receive it earlier in the course of their illness. Multimodal approaches that incorporate tools such as neuroimaging, electrophysiology, electric field modeling and machine learning may enhance our understanding about the mechanism of action of ECT and identify who should receive ECT, as well as identify optimal dosing parameters and electrode placement. We are also in need of research that would explore novel approaches to using ECT that could target a wide range of psychiatric conditions, such as substance use disorders, that are yet to be explored. International collaborations such as International Consortium on the Genetics of Electroconvulsive Therapy and Severe Depressive Disorders (Gen-ECT-ic)


Nature, Florsheim et al. and Plum et al. reported that allergic-specific reactions induced by immunoglobulin (Ig)E mediated mast cell activation is crucial for the timely induction of antigen-avoidance behaviour.2 These studies prove the concept that allergic sensitization triggers the formation of avoidance behaviour and define the underlying molecular mechanism.In two recent studies published in 3 However, these “classical food quality control systems” can detect only a small number of substances and lack the capacity to adapt to novel challenges.Food is composed of a great variety of individual components. It often contains noxious substances, typically acting in a dose-dependent manner. Low doses are often tolerated, but ingestion of higher quantities over longer periods might be harmful. Therefore, a variety of physiological sensors exist that act as “food quality control systems”. They use the olfactory, gustatory, and gut chemosensory systems to induce a variety of physiological reactions such as mucus overproduction, increased peristalsis, nausea, vomiting, diarrhoea, or malabsorption, eventually triggering avoidance behaviour.3 The great advantage of involving the immune system would be its ability to recognize a nearly infinite number of distinct substances in a very specific manner, which is an original property of the adaptive immune system. Therefore, in principle, any dietary protein can cause specific allergic sensitization.Type 1 allergic reactions can induce similar symptoms as already known sensors of food quality. This similarity suggested that type 1 allergic reactions may also act as a ‘food quality control system” that allows learning and behaviour adaptation.Hence, the concept that antibody-mediated allergic responses enable learning and avoidance behaviour was charming but was neither proven nor mechanistically understood. Florsheim et al. and Plum et al. investigated the effects of allergic sensitization on avoidance behaviour in mouse models of food allergy to the model antigen ovalbumin (OVA). Their results show that early type 1 allergic reactions trigger persistent allergen-specific avoidance behaviour, measured by the frequency of licks of OVA containing water. However, mice genetically deficient for IgE or mast cells, and mast cell depleted mice did not develop avoidance behaviour  antibodies which are also induced by IL-4, can trigger anaphylaxis too, though only in the presence of higher amounts of antigen. Antibodies of the subclasses IgG2 and IgG3 are not IL-4 dependent, may not contribute to the pathology of type 1 allergic reactions, but can mediate severe inflammation via the activation of the complement system and various innate effector cells. The studies by Florsheim et al. and Plum and colleagues now show that mice lacking IgE do not avoid allergen ingestion. While most allergic symptoms are absent in IgE deficient mice, even after forced uptake of high amounts of allergen, they still develop severe anaphylaxis, probably involving antibodies of other subclasses. Together, these data are consistent with the notion that IgE is critical for the development of allergic symptoms under physiologic conditions, when allergen avoidance behavior prevents the uptake of the high allergen doses required to induce non-IgE-mediated anaphylaxis. This work reveals a protective role of IgE-mediated mast cell activation, acting via modification of behaviour.IgE and mast cells belong to the same effector cascade of type 1 allergic reactions. IgE binds to the FcεRI on mast cells, arming these cells with an antigen/allergen specific receptor. IgE production is dependent on IL-4 from T follicular helper (Tfh) cells. This cytokine is sufficient to induce low affinity IgE, which however does not induce severe allergic symptoms, while additional cytokines from Tfh13 cells, including IL-13 and IL-21, are required for the development of high affinity IgE and anaphylaxis, a severe and potentially lethal condition.How exactly mast cell activation translates into the modification of behaviours is not yet completely understood. Florsheim et al. showed that even early allergic symptoms are associated with the activation of areas of the brain involved in the response to aversive stimuli. Importantly, the results indicated that the induction of allergen avoidance behaviour required only mild allergic reactions mediated by IgE, which precede the development of gut allergic inflammation. Evidence was provided, that activated mast cells affect behaviour through the release of cysteinyl leukotrienes and the induction of growth and differentiation factor 15 by colonic epithelial cells, eventually sensed by the nervous system. But the target cells within the nervous system remain to be elucidated.1Florsheim et al. suggest that the early IgE-mediated allergic reaction triggers avoidance behaviour while chronic allergen ingestion results in IgE-mediated disease.5 This reflects the fact that antibodies of other subclasses such as IgG1 or IgA can inhibit the severe allergic reactions induced by high-affinity IgE.In accordance with, but also extending this view, we believe that the balance between distinct immune reactions within one individual is the key to understand the role of IgE armed mast cells in immunoprotection and allergy development. The ratios between the levels of allergen specific IgE and the levels of allergen specific antibodies of other subclasses, correlate better with the development of severe allergic symptoms than the levels of IgE alone.The generation of high levels of IgA and IgG and the production of low affinity IgE precedes the formation of pathogenic high affinity IgE. Hence, under conditions when low affinity IgE and antibodies of non-IgE subclasses prevail, it may primarily act as a food quality control system. This is the case at the early, preclinical stage of the allergic reaction. In addition, this mechanism may also be relevant in non-allergic individuals, who nevertheless produce subclinical quantities of IgE, potentially sufficient to cause mild mast cell activation and behavioural change, but without triggering allergic pathology.


For example, PE is primarily synthesized in the Kennedy Pathway through the cytidine diphosphate (CDP)-ethanolamine pathway, where CTP:phosphoethanolamine cytidylyltransferase (Pcyt2) catalyzes the second and rate-limiting step. Because diacylglycerol (DAG) is a substrate in the third and final step of the PE-Kennedy pathway, limitations in Pcyt2 activity are associated with reduced utilization, and therefore increased accumulation of this bioactive lipid, with subsequent consequences for the risk of developing insulin resistance and obesity.5 At the same time, others have found that hepatic insulin signaling can be improved by reducing the ratio of PC:PE through a mechanism that is unrelated to DAG levels,6 but could involve other factors such as modulation of the efficiency of function of the sarco-endoplasmic reticulum calcium ATPase pump,7 which is responsible for more than 20% of energy expenditure overall, and up to half of resting energy use in skeletal muscle specifically.8In organelles where a high degree of membrane curvature is critical for the translation of structure to function, such as in the cristae that form the inner mitochondrial membranes, increases in PE content can improve performance, while losses can result in dysfunction that is so critical as to be incompatible with cellular and organismal life.Pcyt2 global ablation develop nonalcoholic steatohepatitis,5 while liver-specific deletion of this enzyme causes hepatosteatosis without liver injury or impaired hepatic insulin signaling,9 necessarily implicating extra-hepatic organ systems in the pathology.As the largest sink for insulin-stimulated glucose disposal, a central role for skeletal muscle in the regulation of whole body energy and glucose metabolism is well established. Questions remain, however, regarding the role of skeletal muscle PE levels and Pcyt2 activity in the health and metabolic function of this tissue. These questions are particularly perplexing, given that mice heterozygous for Pcyt2 heterozygous gene ablation (+/−Pcyt2), and their findings provide substantial new data linking PE synthesis in this tissue not only to muscle health but also to systemic glucose dysregulation.3 In the current work, the authors examined skeletal muscles from wildtype and +/−Pcyt2 mice, which were used since homozygous loss of this gene is embryonic lethal. Most noticeably, the quality of skeletal muscle changed dramatically with Pcyt2 deficiency, highlighting the critical role of this enzyme in the structural integrity of this tissue. Changes included evidence of degeneration, including the appearance of hyper-eosinophilic cells and vacuolization, as well as disruptions visible under electron microscopy, which included disordering of myofilaments and sarcomeres, resulting in irregular or disrupted Z-lines. Not surprisingly, skeletal muscle tissues from +/−Pcyt2 mice had higher levels of fibrosis and macrophage infiltration compared to tissues from wildtype littermates.In their recent paper, Grapentine and colleagues have investigated the skeletal muscle phenotype in mice with global Cpt1 levels, supported that both higher lipid synthesis and reduced breakdown were factors in the observed myosteatosis. What was surprising, however, was the observation of apparent infiltration of skeletal muscle with adipose tissue cells, rather than just intramyocellular lipid droplets, which appeared in clusters to give a “cloud-like” appearance characteristic of classical adipose tissue depots.Elevated levels of triacylglycerol (TAG) were also found in skeletal muscle fibres from these mice, which was not unexpected, given the disruption to DAG utilization and concomitant rise in DAG content within the tissue. Increased lipogenesis, resulting from elevated Srebp1c activation and enhanced dephosphorylation of acetyl-coenzyme A (CoA) carboxylase, and reduced lipolysis resulting from reduced activation of hormone-sensitive lipase and reduced 10 together with reduced contents of the insulin signaling mediators IRS1, p85-PI3k, and phosphorylated and total Akt, as well as an 87% reduction in the ratio of plasma membrane:total Glut4 protein content. Not surprisingly, this reduced soleus and gastrocnemius glucose uptake under both basal and stimulated conditions in +/−Pcyt2 mice, in association with reduced glycogen synthesis, but enhanced glycogen content.Lipotoxicity significantly impairs glucose handling in numerous models, so the authors studied glucose metabolism in skeletal muscle, and found a near doubling in of levels and activity of the DAG-activated negative insulin signaling regulator protein kinase c (Pkc)α,3 the findings from Grapentine et al. strongly suggest that the age-dependent non-alcoholic steatohepatitis (NASH) and insulin resistance reported in global +/−Pcyt2 mice5 (but not in liver-specific Pcyt2 knockout mice9) originates, at least in part, from pathological changes within skeletal muscle. To explain the overall outcomes, the authors postulated a model of metabolic re-routing. They suggest that reduced activity of Pcyt2 in skeletal muscle results in DAG accumulation that activates Pkcα to impair insulin signaling and glucose uptake, while problems with mitochondrial oxidation and muscle function overall decrease fuel utilization. The authors suggest that this increased the diversion of glucose in skeletal muscle into nonoxidative pathways, such as lipogenesis, which caused inflammation that further inhibited insulin signaling, and together with elevated glycogen stores, also further limited the uptake and utilization by skeletal muscle of glucose. With this major glucose sink diminished, and the tissue inflamed and dysfunctional, the authors suggest that mice became glucose intolerant, and rerouted this excess glucose into the production of TAG in liver.Given that myosteatosis is closely associated with the pathogenesis of nonalcoholic fatty liver disease, to the extent that it is used as a prognostic indicator in patients with end-stage liver disease,+/−Pcyt2mouse. Given the magnitude of effects observed in the current study, future work in mice deficient in Pcyt2 specifically in skeletal muscle would provide an exciting and direct insight into the nature of skeletal muscle–liver crosstalk in hepatosteatosis development and related metabolic complications.Results from this study highlight the importance of PE synthesis in skeletal muscle structure, function, and metabolic health, providing a significant and novel insight into the role of this enzyme and this bioactive lipid in this important tissue. One limitation, which the authors acknowledge, is the use of a global


Ferroptosis is a type of oxidative stress-dependent regulated cell death associated with the iron accumulation and lipid peroxidation. The crosslinks between ferroptosis and autophagy have been focused on since the dependence of ferroptosis on autophagy was discovered. Although the research and theories on the relationship between autophagy and ferroptosis remain scattered and fragmented, the crosslinks between these two forms of regulated cell death are closely related to the treatment of various diseases. Thereof, asthma as a chronic inflammatory disease has a tight connection with the occurrence of ferroptosis and autophagy since the crosslinked signal pathways may be the crucial regulators or exactly regulated by cells and secretion in the immune system. In addition, non-immune cells associated with asthma are also closely related to autophagy and ferroptosis. Further studies of cross-linking asthma inflammation with crosslinked signaling pathways may provide us with several key molecules that regulate asthma through specific regulators. The crosslinks between autophagy and ferroptosis provide us with a new perspective to interpret and understand the manifestations of asthma, potential drug discovery targets, and new therapeutic options to effectively intervene in the imbalance caused by abnormal inflammation in asthma. Herein, we introduce the main molecular mechanisms of ferroptosis, autophagy, and asthma, describe the role of crosslinks between ferroptosis and autophagy in asthma based on their common regulatory cells or molecules, and discuss potential drug discovery targets and therapeutic applications in the context of immunomodulatory and symptom alleviation.Autophagy is an evolutionarily conserved cellular process capable of degrading various biological molecules and organelles  And when the term “apoptosis” was coined in 1972 by Andrew Wyllie, Alastair Currie1, and John Kerr, the surge in RCD research started. Since then, various types of forms of RCD have been explored in the context of the role in multiple pathological and physiological processes of different diseases, the macroscopic morphological alterations, the molecular mechanisms and signaling pathways associated with activation or regulation, and the program in response to varieties of stresses, especially oxidative stress. With multiple novel forms of RCD identified, the core and specific molecular mechanisms have been discovered to insulate the particular form of RCD from others. The research on the regulation of these forms of RCD provided us with novel targets for treating a wide range of diseases. However, it has been increasingly apparent that these molecular programs are deeply interwoven. Studies probing cell death crosstalk have demonstrated multiple molecular interactions between signal transduction pathways and shown that numerous cell death programs are involved in the pathogenesis and pathophysiological process of various diseases. For example, the pyroptotic molecules can activate apoptotic substrates and vice versa, while inhibition of one type of cell death pathway by the pathogen or other signaling defects can result in another pathway of RCD compensating (The crosslinks between ferroptosis and macroautophagy/autophagy have been focused on since the form of autophagy-dependent ferroptosis was discovered. The initiation of autophagy is mediated by the unc-51-like kinase (ULK) complex, which can be inhibited by mTOR complex 1 (mTORC1) or activated by 5′-AMP-activated protein kinase (AMPK) . Then, PI3P-binding molecules can be recruited after the activation of vacuolar protein sorting 34 (VPS34) to form a phagosome  . The autFurthermore, the signal transduction pathways or principal signal molecules of two forms of RCD may be common or cross-linked. The research on these crosslinked pathways and molecules can provide more effective pharmacological targets for improving the prognosis of multiple patients. In addition, both ferroptosis and autophagy have been proven to have a tight connection with innate and adaptive immunity. On the one hand, the activation of immune cells can be regulated by these two forms of RCD. On the other hand, the immune and inflammatory signaling can be controlled by the pathways or proteins of ferroptosis and autophagy.Asthma is a heterogeneous and complex disorder characterized by asthmatic inflammation in the airways. In addition to the chronic inflammation, airway remodeling, and bronchial hyper-reactivity comprise the specific pathogenesis of asthma along with the interaction of non-immune cells such as epithelial cells and airway smooth muscle (ASM) cells, and immune cells including the cells from the innate and adaptive immune systems. Immune factors and various genetic factors interplay in an array of disorders after being stimulated by different environmental factors. Asthma attacks occur over periods of many years, which creates additional therapeutic challenges. Long term structural airway alteration involves multiple cell types and leads to non-reversible obstruction of airflow causing chronic symptoms and, in rare cases, death. New targets for asthmatic therapy have been always discovered based on various areas of lung research to circumvent some of the current limitations of conventional asthma therapy that include tachyphylaxis to beta adrenergic agonists, corticosteroid insensitivity, off-target effects of corticosteroids, and improvement of effective treatments to reverse obstructive airway remodeling.Autophagy and ferroptosis as two crucial forms of RCD have been proved to enrich the strategies of asthmatic therapy. For example, a randomized clinical trial demonstrated that Carbamazepine, an anticonvulsant drug and autophagy inducer had high efficacy in therapy of moderate or severe bronchial asthma . CarbamaHowever, the role of ferroptosis and autophagy in asthma is mostly preclinical evidence, a series of evaluation criteria should be developed before clinical application. As such a large player in general function of cells associated with asthma, autophagy and ferroptosis do provide multiple therapeutic targets. Determining the roles they play in different cell types is key to understanding how to specifically target them. Moreover, in order to reach the best clinical outcome, it is also crucial to consider the stage of development of the disease. Indeed, depending if asthmatic patients are in the initiation or exacerbation phases of the pathogenesis, the specific cell type to be targeted should be considered.via modulating the progress of autophagy and ferroptosis, or discovering some crosslinked targets of ferroptosis and autophagy in various cells which are crucial in asthmatic pathogenesis. All in all, the crosslinks between ferroptosis and autophagy may provide us with more effective targets in various specific cell types to treat asthma.It can be further concluded that the therapeutic schedules to attenuate the symptoms and improve the prognosis for asthma patients can be established based on regulating the innate and adaptive immunity + cDCs can maturate and migrate depending on the transcription factor IRF4 with the effect of danger signals and ‘instructive’ cytokines produced by HAECs. The typical function of DCs as antigen-presenting cells is to internalize antigens and present antigen-derived peptides to T cells. When activated by the innate immune system, CD4+T cells can differentiate into multiple functional subsets of helper T cells such as Th2 cells, Th17 cells, Th1 cells, and Treg cells. Both Th2 cells and ILC2 cells contribute to eosinophilic inflammation by upregulating the expression of GATA-3 which can promote the production of Th2 cytokines, and increase the production of IL-5 to modulate the development of eosinophils, IL-13 leading to goblet cell metaplasia and bronchial hyperreactivity, IL-4 affecting the mature and activation of Th9 cells which can promote the IgE synthesis by B cells. Both Th1 and Th17 cells can result in neutrophilic inflammation by respectively secreting IFN-γ or TNFαand IL-17A or IL-17F Treg cells, a subset of CD4+ T cells, also originate from Th0 cells. The fate of follicular helper T cells (TFH) can be adopted by Th cells producing IL-21 so that IgE can be induced by B lymphocytes.CD11b2Ferroptosis is promoted by iron accumulation and lipid peroxidation. The progress of both initiation and advancement of ferroptosis involves autophagy. The process of autophagy can be divided into non-selective autophagy and selective autophagy. Non-selective autophagy has long been thought to be the main form of bulk degradation pathway, which randomly engulfs a portion of the cytoplasm into autophagosomes and then delivers them to lysosome for degradation. Selective autophagy, however, specifically recognizes and degrades the particular cargo, either a protein complex, an organelle, or lipid droplets . Nonsele2.1The selective autophagy processes which influence ferroptosis included two main parts in the context of regulating the level of iron and modulating lipid peroxidation.2.1.1+ to ferritin, thereby limiting ferroptosis (The level of iron can be regulated by ferritinophagy mediated by nuclear receptor coactivator 4 (NCOA4) , 17. Theroptosis . Similarroptosis .2.1.2The selective autophagy plays a crucial role in modulating lipid peroxidation. Thereof, lipophagy and clockophagy have a tight relationship with free lipid accumulation. Mitophagy and chaperon-mediated autophagy (CMA) are respectively responsible for impaired oxidative phosphorylation and lipid ROS accumulation.Lipophagy can decompose lipid droplets (LDs) which are necessary for cells to resist oxidative stress. Lipid peroxidation has been proved to be induced by polyunsaturated fatty acids (PUFAs) which can be transported into their center along with the formation of LDs .in vitro  in vitro .Compared to the direct relation between lipophagy and free lipid accumulation, the mechanism of clockophagy regulating ferroptosis presents complex. Aryl hydrocarbon receptor nuclear translocator-like (ARNTL/BMAL1) as the center circadian clock protein can be degraded by clockophagy and result in negative modulation of the transcription factor hypoxia-inducible factor 1(HIF1) through transcriptionally upregulating the expression of Egl-9 family HIF2, which is responsible for upregulating expression of specific genes involved in regulating the transport and combination of fatty acids and lipids . When HIF1 is deficient, downregulation of these proteins produced by the aforementioned specific genes can stimulate ferroptosis by preventing the combination of lipids and fatty acids and their transportation from the plasma membrane to mitochondria, and promoting their peroxidation . Sequest-, the cystine/glutamate transporter (- is composed of SLC3A2 and SLC7A11 (via recognizing the m6A binding site within BECN1 coding regions and regulate ferroptosis (- and stabilize system xc- expression (CARS1 (the important member from the aminoacyl-tRNA synthetase family)  , 39.Mitophagy can regulate lipid peroxidation through modulating the function of mitochondria. Most cellular ROS derives from mitochondria. ROS includes a series of byproducts of aerobic metabolism such as hydroxyl radicals (•OH), superoxide anion(O2•–), singlet oxygen (1O2) and hydrogen peroxide (H2O2). On one hand, mitophagy can selectively degrade mitochondria to clear dysfunctional organelles and decrease levels of ROS, therefore, preventing ferroptosis from the perspective of lipid peroxidation prevention. Until now, the identified cargo receptors that take part in mitophagy included CALCOCO2, OPTN, SQSTM1,TAX1BP1 and others . Mitocho2+] from transferrin into the cytoplasm through solute carrier family 11 member 2 [SLC11A2]) has been proven to be impaired due to WDR45 mutation and promote ferroptosis  . AMPK regulation of ferroptosis has been proven to play a critical role in PUFAs biosynthesis and phosphorylation of acyl-CoA carboxylase with the analysis of functional and lipidomic . Both th+ reacts with H2O2 to generate Fe3+, HO·, and OH-. The membrane lipids can be oxidized by these free radical ions . The autophagy receptor for the selective degradation of cadherin 2 (CDH2) can reduce membrane tension and favor lipid peroxidation (Fenton reaction) to increase susceptibility to ferroptosis . In addiWith the development of research, the increasing roles of autophagy have been reported to be comprehensive with multiple crosslinked mechanisms for regulating ferroptosis. For example, TMEM164- mediated autophagy can increase iron accumulation and lipid peroxidation by degrading ferritin, GPX4 and LDs . Insuffivia binding to the AU-rich elements (AREs) within the 3′-untranslated region. The downregulation of ZFP36 can activate ferritinophagy and induce ferroptosis by regulating the signaling pathway of autophagy  mRNA utophagy .3Autophagy is a dynamic process relying on the maturation and formation of specific membrane structures including phagophores, APs, and ALs, which can be generated from the plasma membrane, Golgi complex, recycling endosomes and the ER mitochondria-ER-associated membrane , 57. MecAlthough the direct evidence supporting the critical role of ferroptosis in autophagy is limited, the hypothesis that ferroptosis can regulate autophagy has been confirmed gradually based on the molecular connection between ferroptosis and autophagy. Indeed, erastin-induced ferroptosis can promote the activation of the endoplasmic reticulum (ER) stress response that is regulated by PERK-eIF2α (eukaryotic initiation factor 2α)-ATF4 (activating transcription factor 4) pathway which can inhibit TMZ-induced autophagy , 61. BesThe regulation of autophagy may have a tight connection with ferroptosis in the context of inducing different immune and inflammatory reactions, increasing lipid peroxidation or ROS products (which may impair the function of lysosome to suppress autophagy or induce the damage of mitochondria to initiate the subsequent onset of autophagy), and affecting the common signal transduction pathways.BECN1autophagic gene (Atg6), a conserved NF-κB binding site has been found. Therefore, the NF-κB family member p65/RelA can increase autophagy coupled with upregulating levels of BECN1 mRNA and protein in different cellular systems  pathway which is a crucial regulator in the context of monocyte-to-macrophage differentiation through autophagy , 64. In  systems , 67. DAM systems .The common signal molecules or pathways also play a critical role in the crosslinks between ferroptosis and autophagy. For example, in the cytosol, p53 can block autophagy in a transcription-independent manner, whereas in the nucleus, p53 can activate autophagy in a transcription-dependent way . MeanwhiAnother critical crosslinked signaling pathway was STAT3/Nrf2/GPX4. On one hand, impairing STAT3/Nrf2/GPX4 signaling pathway can reactivate ferroptosis, which can be used to attenuate drug resistance . On the Some crucial crosslinked molecules have been explored to find the connection between ferroptosis and autophagy. The mitochondrial protein, CDGSH iron sulfur domain 1  can mediate the crosstalk between oxidative stress and mitochondrial iron uptake in the outer membrane of mitochondria. The expression of CISD1 has a tight connection with both autophagy and ferroptosis. The overexpression of CISD1 can effectively inhibit autophagic cell death, which can be modulated by a specific regulator miR-127-3p –81. In aHspb1/HSP25, both targeting its catalytic alpha-crystallin domain and the C-terminus, can downregulate autophagy levels  member 1  was confirmed to be central in regulation of autophagy and ferroptosis, which is a molecular chaperone with a function in counteracting protein misfolding and aggregation. The mutations in y levels . In detay levels .The phosy levels , 86. It y levels . Previouy levels . In addiy levels . Meanwhiy levels .Another principal crosslinked target called NEDD4  is a member of the HECT E3 ubiquitin ligases, which is closely related to the mTOR signaling pathway and promotes autophagy . Meanwhi4Both autophagy and ferroptosis are involved in various diseases, and crosslinks between autophagy and ferroptosis in various diseases have been emerging. Autophagy and ferroptosis can be initiated as a defense against varieties of intra- and extra-cellular stress stimuli, which can be achieved in large part through a synergistic immune response. The immune response can lead to alterations of multiple signal molecules which may induce a new round of ferroptosis or autophagy of various cells. The crosslinked intra- and extra- signal molecules or pathways affect the function of leukocytic or non-leukocytic cells and influence the progress of various diseases. The deepened cognition of the role of crosslinks between ferroptosis and autophagy in diseases may provide new targets for therapy, novel signal pathways associated with the pathogenesis of the disease, innovative paradigms to recognize and regulate the immune and inflammatory reactions and in general therapeutic benefits for patients.Although the links between asthma and ferroptosis or autophagy have been confirmed, the role of crosslinks between these two forms of RCD remains unclear. In the latter section, we demonstrate recent advances in the evolving comprehension of the interface between autophagy, ferroptosis and asthma from the perspective of functional cells involved in the pathogenesis of asthma. We discuss how the crosslinked signal pathways in immune or non-immune cells affect the pathogenesis of asthma, how these two forms of RCD reciprocally induce the occurrence of each other through immune and inflammatory signals, how emerging concepts about the crosslinks between ferroptosis and autphagy reshape our understanding of immunity and asthma.IL-13 can increase LC3II expression and then induce autophagy. Meanwhile, IL-13 can induce ferroptosis. IL-33 can activate autophagy through the inhibition of mTORC1. Autophagy can decrease the level of p62 and increase secretion of IL-18.4.1HAECs can promote the regeneration of tissues and protect the body from stimuli, allergens and pathogens by releasing inflammatory response mediators and cytokines such as thymic stromal lymphopoietin (TSLP) and chemokine (C-X-C motif) ligand (CXCL)-8, CXCL1, IL-25, IL-33 and activating innate and adaptive immune systems. The various allergens and proteases can induce the expression of the epithelial cytokines and then promote Th2 immunity by activating conventional dendritic cells (cDCs) and by activating innate lymphoid type-2 (ILC2) cells and basophils that could efficiently polarize IL-4 and/or IL-13 for promoting Th2 immunity and decreasing tolerance to inhaled allergens –98. In oAtg5 knockdown) and expression of LC3-II in order to induce autophagy and then stimulate goblet cell formation and MUC5AC secretion from HAECs  antigens. DCs endure two opposite functional and phenotypic states of maturation. The maturation from a tolerogenic state to the activated one occurs with the help of pathogen-associated molecular patterns (PAMPs), the most characterized type of TLRs. ATG5 and MAP1LC3B regulate TLR stimulation to promote the maturation of DCs Figure 5+ T and CD8+ T cells by MHC class II and class I, respectively. MHC-I can present the extracellular proteins by a process called cross-presentation. CMA has been proved to contribute to the antigen-presenting process by mediating the translocation of substrates across the lysosomal/late endosomal membrane during CMA through overexpression of LAMP2A  and IL-2 receptor (CD25) to suppress allergic responses  have enhanced multiple airway remodeling parameters such as mucus production and airway smooth muscle volume, airway inflammation and epithelial cell proliferation  family and promote the differentiation of peripheral blood mononuclear cells to B cells . This prIn B cells, IL-4 can induce autophagy dependent on JAK signaling. The enhanced ferroptosis sensitivity resulted from the higher expression of CD36 lead to the regulators targeting GPX4 easily inducing antibody response of B1 cells and MZB cells.In neutrophils, NETs formation has a tight connection with peptidyl arginine deiminase 4 (PADI4) and NOX. The PI3K–AKT–mTOR axis is a bridge connecting NET induction and autophagy.Autophagy plays a critical role in the degranulation of mast cells.4.4In asthma, varieties of cells directly result in abnormal symptoms and syndromes by inducing pathophysiologic and histopathologic modification. For example, both eosinophils and mast cells can enhance the permeability of blood vessels. Mast cells contribute to airway remodeling and bronchoconstriction. Eosinophils, neutrophils, basophils and mast cells play an essential role in asthmatic inflammation Figure 34.4.1Eosinophils play a key role in the eosinophilic inflammatory response. Eosinophils can be recruited to the lung from bone marrow by DCs secreting C-C Motif Chemokine Ligand (CCL)-17 and CCL22. Subsequently, Th2 cells and DCs can be further recruited in asthmatic inflammatory reactions.The count of eosinophils in BALF positively related with the expression of LC3-II in lung homogenates, indicating that autophagy has a close relationship with the eosinophilic inflammation as well as the severity of asthma. Eosinophilic inflammation has also been shown to alleviate after intranasal treatment with Atg5 shRNA in the context of significantly improved AHR, decreased amount of eosinophils and IL-5 levels in BALF (autophagy can be induced in isolated blood eosinophils in response to IL-5 treatment), and improved histological inflammatory features . Meanwhi4.4.2Meanwhile, they can fight against pathogens through phagocytosis, degranulation, and neutrophil extracellular traps (NETs). NETs formation has been proven to be upregulated in asthma and has a tight connection with peptidyl arginine deiminase 4 (PADI4) and NOX  through secreting elastin and proteinase 3, when activated by Th17 cells or Th1 cells.  and NOX Figure 7 and NOX , 189. Bo and NOX , 191. Th and NOX . Hence,  and NOX . Ferropt and NOX . Therefo4.4.3Mast cells are granulocytic and hematopoietic leukocytes that degranulate to mediate inflammatory responses. In asthma, the activation of mast cells is stimulated by immune or non-immune cells (such as nerve cells) and various cell surface receptors including TLRs, FcϵRI receptors, hormone receptors and cytokine receptors. Autophagy plays a critical role in the degranulation of mast cells Figure 7When the mechanism of how ferroptosis and autophagy influence the stimulation or dysfunction of the basophils is better known, airway remodeling and asthmatic airway inflammation can be better controlled.The increased expression of autophagy markers is linked to the increased accumulation of ASM mass. ferroptosis participate in the pathogenesis of airway mass in airway remodeling.4.4.4ASM is involved not only in airflow obstruction but also in airway inflammation in asthma. The role of crosslinks between autophagy and ferroptosis in abnormal function (increased contractility/decreased relaxation) of ASM cells or the regulation of the size and number may provide new targets for asthmatic therapy and create the new idea for studying the modulatory network of ASM pathogenesis in asthma. The concomitant expression and association of autophagy with airway modeling have been found. ASM mass is increased in asthma and correlates with poor lung function and increased airway responsiveness to multiple contractile agonists, pollens, allergens and so forth. The increased expression of autophagy markers linked to the increased accumulation of ASM mass confirmed that autophagy plays an indispensable role in airway remodeling Figure 85Both ferroptosis and autophagy are involved in various diseases. The role of these two forms of RCD in treatment has expanded drastically with novel mechanistic details about the regulation and molecular crosstalk between pathways, and the crosslinked effects with immunity and inflammation, which are all previously viewed as independent emerging as topics of particular interest. In this review, we summarize the mechanism of ferroptosis and autophagy and demonstrate the mutual regulation and influence of both of them. Reliance on the common signal pathways and molecules provides multiple potential therapeutic targets. However, the complicated mechanisms of ferroptosis and autophagy make some conclusions contradictory. For example, in macrophages, the suppression of mTOR pathway can activate NF-κB signal pathway, which can enhance the progress of autophagy. But the autophagy induced by TLR2 suppressed NF-κB activation. In DCs, IFN-γ may promote inflammation through ferroptosis, however, suppress the generation of inflammatory cytokines through autophagy. These contradictory mechanisms need to be further explored.In general, for asthma patients, the deepened cognition of common characteristics of ferroptosis and autophagy can be beneficial based on the modulation of target cells or molecules in the direction of equilibrium. This makes it necessary to clarify the exactly crosslinked molecular events and accurate crosslinked effects with the immunity and inflammation, as well as the clarified upstream and downstream mechanisms when autophagy and ferroptosis trigger cell death or we use the crosslinks between ferroptosis and autophagy to implement a therapeutic schedule. Moreover, to improve the prevention, diagnosis, treatment and prognosis of asthma, researchers should explore more about the crosslinks between ferroptosis and autophagy in asthma-related cells and utilize this accumulated knowledge by refining the relationship between immune homeostasis, regulatory mechanisms, inflammation alleviation and symptom relief. If more specific markers of crosslinked pathways can be discovered and relevant key molecular modulators or novel regulatory approaches based on definite mediators performed by immune cells and signals can be confirmed to be effective in asthmatic therapy, the crosslinks between ferroptosis and autophagy and the role in asthma can be further understood, and the regulation of the crosslinked pathways from perspective of cells and molecules will bring the great therapeutic potential for asthma patients.XL and WT wrote the original draft manuscript. JQ, WW, JD and YW reviewed and edited the manuscript. JD and YW supervised the manuscript. All authors contributed to the article and approved the submitted version.


For patients with locally advanced rectal cancer (LARC) or locally recurrent rectal cancer (LRRC), complete tumor removal with clear resection margins (R0) results in the best prognosis. However, when tumors involve multiple pelvic organs and structures, achieving R0 resection can be challenging, particularly in the posterior and lateral compartments, and the procedures carry significant risk of postoperative functional impairment. In other surgical disciplines, in which precise anatomic identification is needed, implementing navigation-assisted surgery has proved to be useful, whereas for rectal cancer, navigation has been reported in only a handful of studies, and indications remain to be defined.1 Manual preoperative segmentation on two-dimensional MRI was found to be time-consuming, but participating surgeons reported that the resulting three-dimensional (3D) model gave an increased understanding of the spatial relations between tumor and adjacent structures. Intraoperative navigation based on optical tracking was accurate, and navigation on segmented anatomy and pelvic bone gave an increased decisiveness during dissection. In the majority of cases, R0 resection was obtained. Based on the experience gained from this trial, the authors believe navigation-assisted surgery may be useful in selected cases of LARC and LRRC.In the NAVI-LARRC trial, the authors investigated the feasibility of navigation-assisted surgery for 17 highly selected LARC or LRRC patients with advanced tumors in the posterior and lateral pelvic compartments.3 the segmentation process needed for creating the images is still laborious. Numerous computer segmentation programs are available, and many allow automated segmentation of pelvic bone as well as semi-automated segmentation of organs with homogeneous radiologic signal, but the tumor and less prominent soft tissue structures still have to be segmented manually to secure precise delineation.4 Deep learning and artificial intelligence might facilitate this, but currently, the tedious segmentation process hinders routine pre- and intraoperative use of 3D imaging.The navigation technology is still in its infancy, and several challenges must be met before navigation can become part of the standard armamentarium for treatment of rectal cancer. Although additional screens in the console monitor allow visualization of 3D preoperative images alongside the view of the operative field in robot-assisted surgery and holographic headsets might soon enable overlay of 3D preoperative images with patient anatomy in the surgical field during open surgery,5 but to the authors’ knowledge, no currently available technology can effectively adjust segmentation boundaries to compensate for movement of multiple pelvic structures in real time. Failure to solve this issue might limit intraoperative navigation for rectal cancer to selected patients with tumors and structures located close to the pelvic bone in the foreseeable future.For intraoperative navigation, the positional shift of soft tissue structures as dissection proceeds is still a challenge. Although the pelvic bone remains in place until resected, segmented soft tissue structures are displaced from their original position upon dissection, leaving the “map” in disagreement with the “ground,” and navigation will no longer be accurate. Solutions to this challenge have been sought,


Lupus nephritis (LN) is a common and severe manifestation of systemic lupus erythematosus and an important cause of acute and chronic kidney injury. Early diagnosis of LN and preventing relapses are key to preserving renal reserve. However, due to the complexity and heterogeneity of the disease, clinical management remains challenging. Kidney biopsy remains the gold standard for confirming the diagnosis of LN and subsequent assessment of kidney histopathology, but it is invasive and cannot be repeated frequently. Current clinical indicators of kidney function such as proteinuria and serum creatinine level are non-specific and do not accurately reflect histopathological changes, while anti-dsDNA antibody and C3 levels reflect immunological status but not kidney injury. Identification of novel and specific biomarkers for LN is prerequisite to improve management. Renal function deterioration is associated with changes in the endothelial glycocalyx, a delicate gel-like layer located at the interface between the endothelium and bloodstream. Inflammation induces endothelial cell activation and shedding of glycocalyx constituents into the circulation. This review discusses the potential role of soluble glycocalyx components as biomarkers of active LN, especially in patients in whom conventional serological and biochemical markers do not appear helpful. SLE has a wide spectrum of clinical manifestations. Kidney involvement, termed lupus nephritis (LN), affects up to 60% of patients, and is an important cause of morbidity and mortality . ImproveAccumulating evidence suggests that vascular inflammation and endothelial cell activation in lupus patients precedes CVD . Increas2The vascular endothelium comprises a monolayer of endothelial cells that lines the entire circulatory system and separates the blood from the interstitial compartments. The integrity of the endothelium is dependent on intercellular junction complexes including tight junctions, adherens junctions and gap junctions; and integrins that facilitate the adhesion of endothelial cells to their underlying substratum . The endThe endothelium also maintains the normal function of the kidney, a highly vascularized organ . The ren3The luminal surface of endothelial cells is lined by a protective glycocalyx, also known as the pericellular matrix or endothelial surface layer. It is a delicate and heterogenous gel-like structure with a thickness ranging from 0.5 - 2 µm and it is composed of negatively-charged proteoglycans and glycosaminoglycans (GAGs) such as heparan sulphate, chondroitin sulphate and HA; glycoproteins bearing acidic oligosaccharides and terminal sialic acids; and plasma proteins including albumin and antithrombin. Glycoproteins such as selectins and cell adhesion molecules are located at the base of the glycocalyx and under physiological conditions, are obscured by a dense layer of proteoglycans covalently bound to the endothelial cell membrane. Proteoglycans such as syndecan-1, syndecan-4 and glypican-1, mask the binding sites of selectins and cell adhesion molecules thereby inhibiting leukocyte adhesion . On the Preserving the integrity of the glycocalyx is essential to maintain vascular homeostasis. Despite its important role in vasculoprotection, the glycocalyx is a fragile structure and can be easily damaged by changes in blood chemistry and flow patterns along the vessel walls, increased levels of hormones, neurotransmitters, vasoactive and atherogenic factors, TNF-α and MMPs, and a loss of plasma components especially albumin in the circulation –29. Infl4Endothelial cell activation, vascular inflammation and kidney injury can be induced through numerous effector mechanisms in LN and include the deposition of oxidized LDL (ox-LDL) in blood vessels, production of autoantibodies against endothelial cells and their subsequent binding to their cell surface antigens, induction of pro-inflammatory mediators including TNF-α, and formation of neutrophil extracellular traps (NETs).Patients with Class 3 or 4 LN show glomerular endothelial injury, characterized by leukocyte accumulation and endocapillary proliferation associated with capillary wall destruction. These detrimental changes are initiated by immune complex deposition in the subendothelial space or thrombotic events in SLE-associated lupus anticoagulant syndrome , 10. TheLong-term use of immunosuppressive medication, impaired immune response, renal impairment and disease activity in LN patients is associated with an increased risk of infection . Neutropde novo synthesis, emerging evidence suggests that MMPs in their activated form are stored in secretory granules in the endothelial cells and can be rapidly released by inflammatory or angiogenic stimuli without prior upregulation of their mRNA  expression inversely correlates with the degree of glomerular injury in LN patients, mediated in part through increased IFN-α signature , 61. AthLipoprotein oxidation is an early event in atherogenesis resulting in the formation of various oxidation products that trigger local immune responses , and mayEndothelial cell apoptosis is a key feature of atherosclerosis and colocalizes with tissue factor activity in atherosclerotic plaques, possibly through activation of the redox-sensitive pathways and redistribution of phosphatidylserine residues , 74. IncNumerous physiological and pathological stimuli can alter endothelial permeability. Thrombin, histamine and pro-inflammatory cytokines can induce opening of adherens and tight junctional complexes through increased PKC phosphorylation, which in turn mediates cytoskeleton reorganization, altered expression of focal adhesion components including vinculin, α-actinin and talin, resulting in changes in cell-matrix interactions, a loss of cell-cell contact and increased paracellular transport . Althoug5Early diagnosis of LN and monitoring of treatment efficacy is challenging, since conventional parameters used in clinical practice, such as proteinuria or deranged kidney function, are likely preceded by a stage of preclinical kidney injury. Kidney biopsy remains the gold standard in the diagnosis of LN and subsequent assessment of kidney histopathology but since it is invasive it is performed infrequently and cannot be repeated frequently. Conventional parameters for the assessment of kidney function such as proteinuria and serum creatinine are non-specific, and do not accurately reflect histopathological changes . Serial Shedding of the glycocalyx constituents into the bloodstream is considered an early sign of endothelial activation and injury , and mea5.1Heparan sulphate comprises more than 50% of the total GAG content in the glycocalyx. It is synthesized in the Golgi apparatus and is composed of repeating disaccharide units of D-glucuronic acid and N-acetyl glucosamine residues. During biosynthesis, the GAG chain can be modified by N-deacetylation or N-sulphation of the glucosamine unit, O-sulphation of both monosaccharide units or C5 epimerization of glucuronic acid to iduronic acid . Given tSyndecan-1 is a transmembrane proteoglycan that has five potential attachment sites for GAG chains and may contain both heparan sulphate and chondroitin/dermatan sulphate GAG chains. Heparan sulphate GAG chains are restricted to the N terminus of the core protein whereas chondroitin/dermatan sulphate GAG chains are attached at the C terminus . ThroughEndothelial cells are constantly exposed to the mechanical shearing forces of blood flow. Changes in the magnitude of shear stress in addition to temporal and spatial distribution have been reported to alter endothelial permeability and hydraulic conductivity and expression of cell adhesions. Fluid shear stress is a potent regulator of vascular homeostasis and induces AKT, Rho A and paxillin phosphorylation in endothelial cells, which play critical roles in NO production, regulation of oxidative stress and cell survival, cytoskeletal remodeling and adherence of endothelial cells to their underlying substratum –99. Hepa-CD38+CD138+ plasma cells suggesting that syndecan-1 may also be derived from CD138+ plasma cells , namely HAS-1, HAS-2 and HAS-3. Nascent HA molecules are extruded through the plasma membrane onto the cell surface or into the extracellular matrix. Despite its simple chemical structure, HA has pleiotropic functions that depend on its molecular weight and tissue distribution. High molecular weight HA possesses anti-inflammatory and anti-angiogenic properties, whereas low molecular weight HA generated by either rophages . Its anirophages . A loss rophages .In a murine model of atherosclerosis, pharmacological inhibition of HA synthesis using 4-methylumbelliferone reduced the thickness of the endothelial glycocalyx and this was accompanied by endothelial dysfunction, increased thrombotic and inflammatory responses with macrophage retention in vascular lesions and a more rapid progression to atherosclerosis . Exposur+ T cell binding  and ICAM-1. Under non-inflammatory conditions, the glycocalyx serves as the first line of defense against leukocyte adhesion and limits the interaction of leukocytes with cell adhesion molecules. Under inflammatory conditions, shedding of the endothelial glycocalyx exposes cell adhesion molecules, which permits circulating leukocytes to adhere to the endothelium followed by diapedesis. Diseases characterized by acute inflammation are often associated with increased E-selectin expression, whereas chronic inflammation is associated with increased expression of VCAM-1 and ICAM-1 . VCAM-1 Adhesion molecules are shed from the activated endothelium following proteolytic cleavage and are detected in the circulation where they could potentially serve as soluble biomarkers of vascular endothelial dysfunction and cardiovascular disease , 146. PlEarly studies that investigated serum VCAM-1 level in SLE and Class 3 or 4 LN patients were conflicting , 151–153As with VCAM-1, conflicting results have also been reported for serum ICAM-1 and E-selectin levels in SLE and LN patients and their association with clinical and serological parameters of disease , 164–1716Early diagnosis of LN, accurate assessment of disease activity and timely monitoring of treatment efficacy is essential for patient and kidney survival, but this remains challenging due to the heterogeneity and complexity of LN. A renal biopsy remains the gold standard for the diagnosis and prognosis of LN but since it is invasive, it is not feasible to perform frequent kidney biopsies for routine monitoring of histopathologic changes and disease activity. Conventional clinical and serological parameters to assess disease activity rely on non-specific indicators of kidney injury or function such as proteinuria and serum creatinine level, which could present late in the course of disease activation and do not reflect histopathologic changes. Serological tests for anti-dsDNA antibody and C3 levels reflect immunological status but not kidney injury and not all patients show an association of anti-dsDNA antibody titre with disease activity. Identification of novel biomarkers for LN should facilitate early diagnosis of nephritic flare and monitoring of treatment response in order to preserve residual kidney function. Biomarkers for LN should accurately reflect disease activity, be reliable and useful in clinical practice, easily measured routinely, have biological and pathophysiological relevance across ethnicities, and show superiority to current conventional markers . FurtherWe and others have shown that constituents of the glycocalyx correlate with disease activity and may have potential diagnostic and prognostic value in LN, endothelial cell activation and possible cardiovascular complications. Drafting the article: SY and TC. Approval of the final version for submission: SY and TC. All authors contributed to the article.