Vaccines represent an important strategy to protect humans against a wide variety of pathogens and have even led to eradicating some diseases. Although every vaccine is developed to induce specific protection for a particular pathogen, some vaccine formulations can also promote trained immunity, which is a non-specific memory-like feature developed by the innate immune system. It is thought that trained immunity can protect against a wide variety of pathogens other than those contained in the vaccine formulation. The non-specific memory of the trained immunity-based vaccines (TIbV) seems beneficial for the immunized individual, as it may represent a powerful strategy that contributes to the control of pathogen outbreaks, reducing morbidity and mortality. A wide variety of respiratory viruses, including respiratory syncytial virus (hRSV) and metapneumovirus (hMPV), cause serious illness in children under 5 years old and the elderly. To address this public health problem, we have developed recombinant BCG vaccines that have shown to be safe and immunogenic against hRSV or hMPV. Besides the induction of specific adaptive immunity against the viral antigens, these vaccines could generate trained immunity against other respiratory pathogens. Here, we discuss some of the features of trained immunity induced by BCG and put forward the notion that recombinant BCGs expressing hRSV or hMPV antigens have the capacity to simultaneously induce specific adaptive immunity and non-specific trained immunity. These recombinant BCG vaccines could be considered as TIbV capable of inducing simultaneously the development of specific protection against hRSV or hMPV, as well as non-specific trained-immunity-based protection against other pathogenic viruses. Candida albicans   , among oin (BCG) Figure 1in (BCG) , 10.Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, Citrobacter rodentium, and Pseudomonas aeruginosa  has been widely used for over a century to prevent the disease caused by M. tuberculosis  when exposed to respiratory pathogens . Indeed,BCG exerts a wide variety of beneficial non-specific immunological effects through the induction of trained immunity, ranging from protection against non-mycobacterial infection, decreased incidence of allergic diseases, and increased immunity to certain cancers . BecauseAlthough the non-specific immune effects induced by the BCG vaccine are broadly reported, the molecular mechanisms involved in this phenomenon are only partially understood. Unveiling these mechanisms would be important to design better therapeutic options and vaccination strategies using this attenuated bacterium.Worldwide, hRSV is considered the most important etiologic agent of acute lower respiratory tract infections (ALRIs) in children under 5 years and adults over 65 years , infectiH1/TH17 memory cells and antibodies in mice ((Good Manufacturing Practices) conditions, showing the same protection against hRSV infection mentioned above in animal models (Vaccines consisting of recombinant strains of BCG expressing either the nucleoprotein (N) or the M2 protein of hRSV  were evaluated to induce hRSV specific immunity and prevent disease , 89–92.  in mice , 89, 91. in mice , which cl models . In a phl models .HMPV also causes ALRIs and death in children under 5 years old . This viBased on the previous experience with hRSV, recombinant BCG vaccines expressing either the phosphoprotein (P) or the M2.1 protein of hMPV were generated . Both, rThese recombinant BCG vaccines were based on BCG-Danish 1331, a vaccine that is known to induce trained immunity, suggesting that this type of immunity might be a component of the protection achieved with these vaccines against these two respiratory viruses. Consistently with this notion, vaccination of RAG-deficient mice, which lack T and B cells, with rBCG-N-hRSV induces the secretion of significantly higher IFN-γ levels in bronchioalveolar lavages (BAL) after hRSV challenge as compared to unimmunized mice . SurprisDuring viral infections, the immune system activates the production and secretion of interferons, which mediate the antiviral response, impairing the viral replication by the activation of macrophages and DC . As mentBased on the studies mentioned above, vaccination of the risk population with either rBCG-N-hRSV or rBCG-P-hMPV, besides inducing specific protection against the virus for which they are developed, may induce non-specific cross-protection mediated by a trained innate immune system against other viruses to which there is no specific vaccine available Figure 2Listeria monocytogenes gene encoded for listeriolysin instead of the urease C gene . FONDECYT N°1170964 and 1190830. AK is a Helen C. Levitt visiting professor at the Department of Microbiology and Immunology of the University of Iowa.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.


The introduction of gonadotrophin-releasing hormone agonist (GnRHa) trigger greatly impacted modern IVF treatment. Patients at low risk of ovarian hyperstimulation syndrome (OHSS) development, undergoing fresh embryo transfer and GnRHa trigger can be offered a virtually OHSS-free treatment with non-inferior reproductive outcomes by using a modified luteal phase support in terms of small boluses of human chorionic gonadotrophin (hCG), daily recombinant luteinizing hormone LH (rLH) or GnRHa. In the OHSS risk patient, GnRHa trigger can safely be performed, followed by a ‘freeze-all’ policy with a minimal risk of OHSS development and high live birth rates in the subsequent frozen embryo transfer cycle. Importantly, GnRHa trigger opened the ‘black box’ of the luteal phase, promoting research in the most optimal steroid levels during the luteal phase. GnRHa trigger allows high-dose gonadotropin stimulation to achieve the optimal number of oocytes and embryos needed to ensure the highest chance of live birth. This review thoroughly discusses how the GnRHa trigger concept adds safety and efficacy to modern IVF in terms of OHSS prevention. Furthermore, the optimal luteal phase management after GnRHa trigger in fresh embryo transfer cycles is discussed. Traditionally a bolus of human chorionic gonadotrophin (hCG) has been the gold standard for ovulation induction and final oocyte maturation in assisted reproductive technology (ART) cycles as a surrogate for the natural mid-cycle luteinizing hormone (LH) surge. However, the increased glycosylation of hCG results in a prolonged bioactivity which in combination with the sustained luteotropic activity may induce ovarian hyperstimulation syndrome (OHSS), one of the most serious complications of controlled ovarian stimulation (COS) . AdditioWhen gonadotrophin-releasing hormone (GnRH) antagonist protocols were introduced for the prevention of a premature LH surge  it becamThe syndrome OHSS was already described in 1941 . In sponThe most significant benefit of GnRHa trigger is its ability to induce a quick and reversible luteolysis and, thus, reduce the risk of OHSS development. In GnRH antagonist cycles, GnRHa trigger has been utilized to induce the final stage of follicular maturation while reducing the risk of OHSS. This protocol works because GnRH agonists have a greater affinity for the GnRH receptor than GnRH antagonists have. Thus, a bolus of GnRHa can displace the GnRH antagonist from the receptor, resulting in a surge of LH as well as FSH. The lower mean LH concentrations and decreased LH pulse amplitude and activity over the luteinized granulosa/theca cells in addition to an upregulation of the apoptosis of granulosa cells induce the process of luteolysis early in the luteal phase, which seems to be key factors for OHSS prevention after GnRHa trigger ,21. InteFrom a clinical point of view, the most optimal strategy to prevent OHSS starts with the identification of OHSS risk patients in order to adapt the ovarian stimulation regimen accordingly and subsequently plan the trigger agent. In patients at risk of OHSS, some clinicians might opt for elective frozen embryo transfer (eFET). It has, however, been proven, during a series of randomized controlled trials (RCTs), that GnRHa trigger enables a fresh transfer if modifications of the luteal phase support (LPS) are performed, and, importantly, the reproductive outcome is non-inferior to hCG trigger ,23–26. HOocyte/embryo freezing, so-called ‘freeze-all’, segmentation or eFET, was recently proposed for all GnRHa-triggered IVF cycles ,29 and iA recent meta-analysis comparing fresh transfer to FET supports the use of eFET in hyper-responder patients and patients undergoing PGT-A (preimplantation genetic testing for aneuploidy) ; howeverAlthough there is a lack of randomized clinical trials comparing GnRHa-triggered fresh and eFET cycles, evidence from observational studies suggests that GnRHa triggering combined with oocyte/embryo vitrification and embryo transfer in a subsequent cycle provides patients at high risk of developing OHSS a safe and efficient alternative. In this high-risk population, a freeze-only approach to minimize the risk of OHSS may outweigh the known and unknown risks and the financial costs involved with the eFET strategy. Nonetheless, results from large long-term follow-up trials in children conceived as a result of frozen–thawed embryo transfer and the exploration of possible obstetric complications are mandatory before the widespread adoption of a ‘freeze-all ‘policy can be recommended.Luteal phase insufficiency, resulting in an unacceptably high early pregnancy loss rate, despite the use of a standard LPS was seen during the early studies of GnRHa trigger ,37. FollAs noted previously, while the lower LH activity commencing early in the luteal phase was a beneficial key factor for OHSS prevention, it was also responsible for the disappointing lower reproductive outcomes in GnRHa-triggered compared with hCG-triggered cycles. Thus, the question was: how can LH activity be introduced after GnRHa triggering to most optimally restore the luteal phase?Based on two small pilot studies in IUI patients ,42, the Based on available evidence, GnRHa trigger followed by a single low-dose bolus of hCG and fresh transfer prevents or significantly reduces the risk of OHSS while providing high pregnancy rates. However, it is crucial to have an upper cut-off limit of follicles before embarking on this strategy. Based on our previous studies and daily clinical experience we suggest a cut-off of >25 follicles ≥11 mm .Theoretically, the addition of recombinant LH (rLH) will overcome the defective luteal endocrine/endometrial environment and restore luteal function after GnRHa trigger. Due to the shorter half-life of rLH compared with hCG, the risk of OHSS may be further reduced. Papanikolaou et al. explored this interesting concept in a pilot study, applying repeated doses of rLH as a luteal supplementation  post GnRHa trigger and compared this concept to a standard hCG trigger and LPS . SimilarAn early small study in OHSS risk patients by Babayof et al.  exploredAn ongoing pregnancy rate of 53% and no OHSS was reported in the GnRHa trigger group compared with 34% (10/29) in the hCG trigger group. Some groups, applying a similar exogenous intensive luteal support regimen, reported favourable results after fresh transfer in retrospective studies ,50. Howep = 0.02) and clinical pregnancy rates  were significantly higher in patients with peak E2 levels ≥4000 pg/mL compared with those with peak E2 levels <4000 pg/mL. Patients within these limits might also have higher LH levels during the luteal phase, leading to a hypothetically higher degree of CL rescue, higher progesterone and E levels, and subsequently higher implantation rates. The authors hypothesized that some form of low-dose LH-like activity might rescue CL function in patients with low peak serum E2 levels without significantly increasing the risk of OHSS. Following this, the authors suggested administering low-dose adjuvant hCG in women with peak serum E2 < 4000 pg/mL, in line with the proposed protocol by Humaidan et al.  . In theiAnother retrospective analysis including a total of 102 IVF/ICSI (intracytoplasmic sperm injection) cycles in OHSS high-risk patients having peak serum E2 levels <4000 pg/mL reported that the use of dual trigger (GnRHa and a fixed dose of 1000 IU hCG) resulted in a significantly higher live birth rate (52.9% versus 30.9%), implantation rate (41.9% versus 22.1%), and clinical pregnancy rate (58.8% versus 36.8%) compared with GnRHa trigger only . In bothTaken together, data from observational analyses support the idea, that, taking into account oestradiol levels on the trigger day and luteal function markers, monitoring with appropriate dose adjustment seems important when deciding whether dual trigger or steroids only should be used to support the luteal phase of patients at risk of OHSS development. This is in the absence of RCTs evaluating the optimal timing and dosage of hCG to be given alongside GnRHa trigger.The idea of only supporting the luteal phase after GnRHa with daily doses of intranasal GnRHa was initially explored in 17 and 40 patients, respectively ,57. MoreThe same group subsequently retrospectively reported the outcomes of 1436 cycles triggered with hCG, using repeated daily nasal GnRHa administration as the sole LPS. Higher live birth rates were reported with this protocol when compared with a retrospective cohort of 1093 patients having daily vaginal LPS after hCG trigger . The potThe introduction of the GnRHa trigger in modern IVF revolutionized ovarian stimulation and ovarian trigger concepts. Moreover, it opened the ‘black box’ of the luteal phase. Currently, patients undergoing fresh embryo transfer who are not at risk of OHSS development can be offered a virtually OHSS-free treatment in addition to good reproductive outcomes with modifications of the LPS after GnRHa trigger in terms of small boluses of hCG, daily rLH, or GnRHa. Although recent RCTs investigate further fine-tuning of the modified LPS, more studies are needed to reach a consensus on the optimal strategy. In the OHSS risk patient GnRHa trigger can be safely performed, followed by a ‘freeze-all’ policy with a minimal risk of OHSS development and high live birth rates in the subsequent FET cycle. Taken together, the GnRHa trigger concept adds safety, efficacy, and patient-friendliness to modern IVF.


Total rehabilitation is one of the most sophisticated kinds of dental implant-supported prosthetics. The usage of multiunit abutment system allows the clinician an accurate and passive fitting of screw-retained full-arch construction. In addition, it retains a condition of soft and bone tissues around prosthetic construction. The aim of this case is to demonstrate a modern approach in planning and realisation of full-mouth screw-retained dental implant prosthetics. A 59-year-old patient had an extraction of all failed teeth on upper and lower jaws with immediate 16 implant placement (8 implants on maxilla and 8 implants on mandible) using surgical template. Multiunit abutments were installed intraoperatively. Temporary constructions were fixed immediately after surgery. After 3 months of dental impressions, plaster models and their scan were prepared to make final screw-retained zirconium dioxide constructions. Reevaluation of functional and aesthetic result of the treatment was made after 12 months. Dental implantation is a well-documented treatment of partial or full adentia , 2. SuccA 59-year-old male patient came to department of surgery dentistry at the Institute of Dentistry (Sechenov University) complaining about partial teeth absence, difficulty in chewing, and dissatisfaction in teeth aesthetics. According to the patient, he loses his teeth gradually over 20 years due to caries and its complications . ProstheSupporting teeth failure was revealed after cone-beam computed tomography and removal of old prosthetic constructions. The treatment plan was composed under functional and aesthetic analysis, which included the extraction of all teeth with immediate 16 dental implant placement (8 implants for each jaw) and intraoperative multiunit abutments installed with immediate loading. The making of zirconium dioxide fixed screw-retained prosthesis by multiunit abutment level was planned after a period of osseointegration. Received CBCT images and scanned plaster models were exported into programme application Implant Studio . Placement and sizes of dental implants were chosen after evaluation of bone situation and position of virtual prosthetic construction .Two surgical templates were made for each jaw. The first template was positioning the teeth-supported surgical template containing sleeves for drilling intraosseous holes for the placement of fixation pins. The localisation of these holes fully matches similarly in the second, full-guided surgical template attached on the edentulous jaw by fixation pins in the same intraosseous holes after extraction of all teeth. Thus, maximum accuracy of the full-guided template was achieved on working on edentulous jaws . The patThe patient received a prophylactic dose of antibiotic  1 hour before surgery. All procedures were performed with local anaesthetics. Intravenous sedation was patient's request. After local anaesthesia by Ubistesin , positioning the surgical template was attached on each jaw, and intraosseous holes for fixing pins were drilled to a specified depth, and then, the templates were removed. Afterwards, all of patient's teeth were extracted by using Periotome  and gentle elevation with forceps to prevent a fracture of the facial alveolar bone. All extraction sockets were thoroughly treated with aggressive curettage. Before immediate implant placement, a decontamination protocol was performed by packing extraction sockets soaked in 0.2% chlorhexidine gluconate gauze and keeping there for 5 min in situ. Then, on each edentulous jaw, the full-guided surgical template was attached tightly by fixing pins to previously prepared intraosseous holes. Placement of 16 SGS dental implants  (8 implants on each jaw) was performed under standard protocol. Eight SGS implants were used on the maxilla with aggressive thread (P7), and they were placed transmucosally (flapless). The criteria for the flapless surgery were an adequate amount on the bone for implant placement, the presence of 2 mm thickness each bone on buccal and palatal sides around implant as planned in a favourable prosthetic position , and the presence of sufficient keratinised attached gingiva (it must be at least 3 mm around the each implant) .SGS implants P1 were used on the mandible with parallel surfaces and placed by forming mucoperiosteal flap and standard protocol drilling, excluding places where extraction sockets were located, as immediate implantation was made there using the flapless method .All the implants were placed with minimal torque above 50 Ncm. Afterwards, the selection of multiunit abutments  was made intraoperatively. For the four implants in the front of maxilla, two-component 30-degree multiunit abutments were chosen, and left over on the distal side are four direct one-component multiunit abutments. All of these multiunit abutments have the height of the transgingival part equal to 2 mm. For the mandibular implants, direct one-component multiunit abutments were chosen with the height of the transgingival part equal to 1 mm. Thus, all of the multiunit abutments were installed intraoperatively with a torque equal to 25 Ncm, and their removal was not performed in the future .Then on multiunit abutments were installed healing abutments and made 6-0 Prolene  monofilament interrupted sutures to close the flaps. Augmentation of extraction sockets by xenograft was not performed. Full-arch maxillary and mandibular impressions were made from multiunit abutment platform with appropriate transfers for open tray with polyether impression material  and sent to the laboratory for making first temporary constructions in centric occlusion relationship. The prepared temporary restorations were attached after 4 h with recommended torque equal to 10 Ncm, and target X-rays of the implant suprastructure systems were performed.The patient was instructed for postoperative oral care like rinsing oral cavity with 0.2% (by volume) chlorhexidine gluconate mouthwash  solution twice a day for a week and cleaning the temporary restorations with an extra fine toothbrush. The patient received an antibiotic  twice a day for 5 days. For pain control, the patient was prescribed a 100 mg of nimesulide . The patient was also advised to minimise trauma at the surgery site; no special diet was recommended. The sutures were removed 10 days after the surgery.Further prosthetic procedures were initiated after 2 months of soft and bone tissue healing. For centric relation (CR) definition, Kois Deprogrammer was prepared and recommended to wear for 8 h each day for a week. After that, second temporary constructions in CR relationship were prepared. Another month later (3-month postoperative), the impression was taken on a multiunit abutment level with transfers for open tray with polyether impression material . Temporary prosthetic constructions were installed to prepared plaster models, which were mounted on the articulator SAM 3  .The prostheses were designed on the ExoCAD software . An epoxy resin prototype was printed and sent to verify the lip support, midline position, incisal edge position and teeth display, occlusal plane orientation, centric relation, phonetics, and aesthetics for the sake of patient's satisfaction. After some adjustments, the restorations in full anatomy were milled in monolithic zirconia block   and wereThe final full-arch prostheses were clinically verified with a one-screw test for passive fitting. The prosthesis screws were tightened following the instructions to 15 Ncm. The screw access holes were filled with temporary material. Functional specificities, including group function, interocclusional contacts, no contacts on protrusive and lateral excursions, were achieved by minor selective modifications, central fossa expansions on premolars and molars and teeth appearance reduction Figures  and 10.Finally, the aesthetics and phonetics were verified. Occlusion check was made by articulation paper 100-micron thickness . Three days later, the occlusion recheck was made by articulation paper 48-micron thickness . Front teeth in full contact 8-micron disocclusion were achieved. Screw access holes were filled with the flowable resin Filtek Ultimate Flow . Postoperative instructions including hygiene care were advised to the patient. For outcome and follow-up, the patient was surveyed after 6 weeks and 12 weeks postoperatively for monitoring the stability of the implants and assessing the health of the peri-implant tissues. Postoperative instructions including hygiene care were advised to the patient. Multidisciplinary regular check-up was emphasised. The patient was followed at 1, 3, 6, and 12 months post loading. CBCT scanning was taken after 12 months, and no any bone resorption around implant platform was found . Soft tiZirconium as a material for permanent restorations has many beneficial characteristics such as low temperature conductivity and corrosion potential, low bacterial contamination, and high biocompatibility . The maiDental implant positioning accuracy is an important factor in full-arch implant-supported rehabilitation, especially when the final restoration should be prepared without any ceramic gingiva (“nature-like” teeth). Virtual-guided technologies provide optimal implant placement according to the correct prosthetic position and minimise intraoperative trauma and procedure time.Screw retaining prostheses have some advantages against cement-retained constructions like an absence of cement in peri-implant tissues and a maintenance service possibility . The multiunit abutments provide absolutely passive fitting of prosthesis even with significant divergence of placed implants axes.Intraoperative installation of multiunit abutments allows to seal an implant neck and to create a new, stronger, and wider hemidesmosomal connection on the multiunit abutment neck level and makes it possible to avoid multiple screwing/unscrewing, preserving the stability of peri-implant tissues.


Intracranial neoplasms are an uncommon cause of symptomatic parkinsonism. We here report a patient with an extensive middle and posterior fossa arachnoid cyst presenting with parkinsonism that was treated by neurosurgical intervention.Retrospective chart review and clinical examination of the patient.This 55-year-old male patient with hemiparkinsonism and recurrent bouts of headaches was first diagnosed in 1988. CT scans revealed multiple cystic lesions compressing brainstem and basal ganglia, which were partially resected. Subsequently, the patient was free of complaints for 20 years. In 2009 the patient presented once more with severe unilateral tremor and thalamic pain affecting the right arm. Despite symptomatic treatment with L-Dopa and pramipexole symptoms worsened over time. In 2014 there was further progression with increasing hemiparkinsonism, hemidystonia, unilateral thalamic pain and pyramidal signs. Repeat CT scanning revealed a progression of the cysts as well as secondary hydrocephalus. Following repeat decompression of the brainstem and fenestration of all cystic membranes parkinsonism improved with a MDS- UPDRS III score reduction from 39 to 21. Histology revealed arachnoid cystic material.We report on a rare case of recurrent symptomatic hemiparkinsonism resulting from arachnoid cysts. Arachnoid cysts are constituted of fluid collections within the central nervous system, which commonly remain asymptomatic. Occasional symptomatic forms are described to result in hemiparkinsonism –3. A conA 29-year-old male patient complained about recurrent bouts of headaches. In the following month he developed a progressive right-sided slowness, which limited his ability to work. On admission to hospital in 1988 he was diagnosed with strictly right sided parkinsonism, however, the symptoms were only partially responsive to levodopa. CT scans revealed multiple cystic lesions within the brainstem as well as a posterior cerebral artery aneurysm. Due to the severity of the motor symptoms as well as the indication of surgical treatment for the aneurysm, the patient underwent neurosurgical intervention with partial resection of the cystic lesions and aneurysm clipping at an outside institution. Subsequently, the patient was asymptomatic for 20 years and able to pursue his former work without any physical limitations. In 2009 the patient presented again with chronically progressive unilateral tremor and thalamic pain affecting the right arm. DAT-SPECT revealed severe strictly unilateral dopaminergic denervation on the left side. Despite symptomatic treatment with escalating dosages of levodopa and pramipexole, symptoms worsened over time  part III, improved with a score reduction from 39 (pre-operatively) to 21 (postoperatively), showing a very good response of motor symptoms to the treatment. The pre and post-operation video assessment is included in the supplementary file. Concerning the non-motor symptoms, thalamic pain as well as depression improved markedly. The follow-up CT scan revealed no significant volume change of the cystic lesions Neuropathological examination revealed features of arachnoid cysts.Additional file 1 Pre-operative assessment (18/11/2014) In this video the patient is shown before surgery presenting with a marked gait dysfunction and instability. Post-operative assessment (02/12/2014) The patient is shown at day 12 after surgery. Parkinsonian symptoms are markedly improved. The patient now exhibits a slight hemiparesis due to cystic lesions, which improved over time.At last follow-up in April 2016 the patient marginally deteriorated again on a daily dose of 1200 mg of levodopa. He reported motor fluctuations with shuffling of gait, increasing rigidity, nervousness and dystonia during Off-periods. Neurological examination revealed secondary right-sided hemiparkinsonism with superimposed hemi-ataxia, and spastic hemiparesis, although repeated CT scans demonstrated no significant morphological change.Secondary parkinsonism caused by arachnoid cysts is rarely described –3. ArachIn contrast, invasive treatment strategies can be considered for symptomatic arachnoid cysts, as they may cause multiple impairments such as headache, paresis, parkinsonism, seizures, hydrocephalus, cognitive decline and visual loss , with heThe optimal surgical treatment option for such lesions is debated –7. RecenVarious cortical and subcortical lesions are known to cause parkinsonism  and therCyst recurrences after surgery were thought to be rare  as was sPatients suffering from symptomatic parkinsonism may exhibit all types of parkinsonian signs including akinesia, rigidity and tremor . HoweverWe here report a patient with symptomatic levodopa-refractory hemiparkinsonism resulting from extensive arachnoid cystic lesions disrupting contralateral basal ganglia. Neurosurgical decompression resulted in extended periods of remission or improvement in this patient, however, future studies are needed to determine the effectiveness of this treatment.


This review provides a comprehensive summary of the key findings, limitations, and clinical impacts of these techniques to quantify musculoskeletal soft tissue strains during dynamic movements. Current technologies generally leverage three techniques to quantify in vivo strain patterns, including implantable strain sensors, virtual fibre elongation, and ultrasound. (1) Implantable strain sensors enable direct measurements of tissue strains with high accuracy and minimal artefact, but are highly invasive and current designs are not clinically viable. (2) The virtual fibre elongation method tracks the relative displacement of tissue attachments to measure strains in both deep and superficial tissues. However, the associated imaging techniques often require exposure to radiation, limit the activities that can be performed, and only quantify bone-to-bone tissue strains. (3) Ultrasound methods enable safe and non-invasive imaging of soft tissue deformation. However, ultrasound can only image superficial tissues, and measurements are confounded by out-of-plane tissue motion. Finally, all in vivo strain measurement methods are limited in their ability to establish the slack length of musculoskeletal soft tissue structures. Despite the many challenges and limitations of these measurement techniques, knowledge of in vivo soft tissue strain has led to improved clinical treatments for many musculoskeletal pathologies including anterior cruciate ligament reconstruction, Achilles tendon repair, and total knee replacement. This review provides a comprehensive understanding of these measurement techniques and identifies the key features of in vivo strain measurement that can facilitate innovative personalized sports medicine treatment.The critical clinical and scientific insights achieved through knowledge of  In addition to considerable pain and loss of function experienced by patients,in vivo ligament and tendon strains is not only important for identifying injury mechanisms, informing surgical reconstructions and optimizing rehabilitation protocols, but also essential for defining physiologic loading conditions for in vitro experiments and tissue engineered constructs. Therefore, the measurement of in vivo musculoskeletal soft tissue strain patterns during functional movements is critical for both facilitating scientific discoveries and driving innovative clinical treatments.Transforming sports medicine therapies to address current treatment shortcomings requires a comprehensive understanding regarding the functional demands withstood by musculoskeletal soft tissues during activities of daily living in healthy, injury, and pathologic conditions. A detailed understanding of in vivo measurements of tissue strain magnitudes and rates during dynamic movements.The importance of soft tissue strain to biomechanical tissue function and adaptation has been well established. In 1847, Wertheim demonstrated that the stress-strain relationship in animal tissue does not follow the linear relationship dictated by Hooke’s law.in vivo ligament strainsin vivo ACL strain showed a significant increase when the knee moved to extended postures,in vivo strain data available for many other ligaments and tendons, especially during functional and rehabilitative activities.In clinical settings, improved knowledge of In vivo strain measurements also provide critical insights into muscle-tendon function by enabling the elongation of the muscle fibres, tendon, and aponeurosis to be independently quantified.in vivo strain measurements to reveal the complex interactions within muscle-tendon units to conserve energy during muscle contraction, amplify power output, and absorb shocks during impact.142in vivo soft tissue strains will also provide important insights into how humans modulate their neuromuscular coordination to generate movement. When coupled with traditional motion analysis techniques, in vivo strain measurements could enable an improved understanding of how the body leverages elastic energy storage in tendons.137An improved understanding of in vivo quantification of musculoskeletal tissue strain for both clinical and basic science applications has inspired the development of three main measurement techniques: (1) implantable strain sensors, (2) virtual fibre elongation, and (3) ultrasound. Implantable strain sensors have largely been applied to measure in vivo ACL strains,in vivo ligament and tendon strains. Ultrasound technique enables dynamic non-invasive planar imaging of soft tissue structures, and has mostly been applied to measure musclein vivo strain measurement have been previously reviewed,in vivo tendon and ligament strain measurement methodologies and their key findings, clinical implications, and limitations, as well as to identify technological developments that may lead to clinical and basic science advances in sports medicine.The critical need for Articles were searched using the keywords “sensor*”, “gauge*”, and “transduc*”, “imag*”, “ultrasound*”, “fluoroscop*” as well as “tendon*”, “ligament*, “muscle*”, “length change*”, “strain*” and “elongat*” in the Pubmed and EMBASE databases. A total of 9842 articles were found. The titles and abstracts of all articles were firstly screened by one author to exclude clearly irrelevant articles. Two authors then reviewed the full texts of the remaining articles to identify articles discussed in this review. As this is a narrative review, the two authors also searched the reference lists of these articles to identify any other relevant articles that had not been found through the above search. One experienced author discussed these candidate articles with the two authors to make a final decision on their inclusion. Finally, 151 articles were includedor reviewing.ε) is traditionally defined using Eq. . Buckle transducers, liquid metal strain gauges, fibre optic transducers, and sonomicrometry crystals have all been used for in vivo force and strain measurements in animal studies to assess muscle, tendon, and ligament function during dynamic activities.strain patterns in rabbit ATs and in horse suspensory ligaments.force in humans during walking and jumping.52Implantable sensors have been employed to directly measure in vivo strains in human musculoskeletal tissue.While many aforementioned sensor designs have been demonstrated for force measurements in humans and strain measurements in animals, only Hall Effect Strain Transducers (HESTs) and Differential Variable Reluctance Transducers (DVRTs) have been used to directly measure To detect displacement, HEST sensors measure the change in voltage resulting from relative movement between a magnet and a Hall-effect magnetic sensor, whereas DVRTs measure the movement of a magnetic core within two coil windings by measuring the resulting change in magnetic reluctance.46in vivo ACL slack length, Beynnon and co-workers recorded the displacement of a HEST sensor fixed on the ACL while applying antero-posterior shear loads to the tibia.47To assess In vivo strain sensor measurements have provided critical insights into rehabilitation protocols for ACL reconstruction by providing direct evidence for activity selection that ensure tissue strains are under damaging magnitudes,in vivo ACL strain measurements using DVRT sensors have revealed that peak strains induced by squatting (3.6%)In vivo sensor measurements have also revealed key insights into the role of muscle activation in both loading and protecting the ACL. The measurements indicate that isometric quadriceps contractions increase ACL strain at flexion angles of less than 50°,There are several unique advantages to the HEST and DVRT implantable sensor approaches for strain measurement. Firstly, it provides a direct strain measurement and thus the data is highly representative of the local tissue strain environments. Secondly, both HESTs and DVRTs are highly sensitive and able to detect minute strains in the musculoskeletal tissues.Invasive nature: Sensor implantation is a highly invasive procedure, resulting in ethical difficulties to justify their use in healthy subjects. For ACL strain measurements, implantations have therefore typically been undertaken together with a pre-planned arthroscopic surgery to perform minor repairs of neighbouring tissues.193Tissue impingement: Current sensors can only be implanted in locations where there is sufficient room for the sensor and straight-forward surgical assess to the tissue. For example, the strain sensors have always been attached to the anteromedial bundle of the ACL because it is more accessible from the anterolateral surgical portal than the posterolateral bundle of the ACL. While HEST and DVRT sensors are small in size, their solid constitution can result in impingement with surrounding musculoskeletal tissues, and therefore impede certain postures during testing. Importantly, sensor disturbance with the femoral notch is unavoidable at full extension of the knee during ACL strain measurements,44Limited implantation duration: Previous experiments have been limited to a few hours because both HEST and DVRT sensors require a cable that crosses the skin to transmit the measurement signal, and are therefore not long-term biocompatible. These limitations have prevented subjects from performing many functional activities of daily living.Sensor-body interference: Sensor cable migration induced by subject body movement can cause significant artefacts in the sensor signal. Sensor cables should be stabilized and well protected during experiments.Sensor implantation alignment: Measurements are sensitive to implantation orientation of the sensor relative to the tissue. To assess tensile ligament strains, the measurement axis of the sensor must be aligned with the ligament fibres during implantation in order to record uniaxial strain.Despite the insightful findings, however, the HEST and DVRT sensors have several major limitations:Recent advances in stretchable electronics may enable clinical translation of strain sensors towards intraoperative guidance and long-term assessment of healing. To facilitate these clinical applications and minimize risk to research subjects, these next generation strain sensors should incorporate three critical features: flexibility, wireless data transmission, and long-term biocompatibility. Thin and soft membrane-like strain sensors can be fabricated by embedding conductive materials in stretchable materials to reduce the risk of tissue impingement.Initial imaging assessments of ligament strain were achieved using open-MRI67Typically, the joint of interest is statically imaged using MRThe length change of a ligament during a movement is assessed by tracking the relative displacements of the attachment points. For ligaments with small attachment footprints, a virtual fibre connecting the centroids of ligament insertion sites is defined as the ligament “longitudinal axis”.163The virtual fibre elongation method does not provide any inherent means to determine the slack length of a tissue. Accordingly, most studies using this method define the reference length as the length of a tissue in a reference joint posture, to normalize length change measurements and provide an estimate of the elongation patterns. For the knee ligaments, the length at full knee extensionThe primary advantage of the virtual fibre elongation method is that it enables the non-invasive assessment of multiple ligaments in a joint during dynamic movements. The resulting comprehensive understanding of ligament contributions to functional joint mechanics has informed many surgical and rehabilitative sports medicine procedures. Using the virtual fibre elongation method, ACL length was shown to decrease by 28% from full knee extension to 135° of knee flexion during single leg lunge,172The virtual fibre elongation method also provides insights into the strain distribution within tissues by using multiple fibres. This techniques has revealed that the anterior, middle, and posterior bundles of the superficial MCL exhibit different length change patterns  from full knee extension to 145° knee flexion during lunges.The virtual fibre elongation method can also evaluate the outcomes of surgical procedures via the length change patterns of ligaments or grafts during functional movements. A possible mechanism for poor outcomes in PCL-retaining total knee arthroplasty (TKA) patients was identified because PCL elongation showed a significant increase compared to healthy knees at flexion angles of over 75° during lunges.The virtual fibre elongation method leverages state-of-the-art dynamic imaging technologies to non-invasively evaluate soft tissue strains throughout functional activities at high frequencies (> 200 Hz). It can quantify regional tissue strains by using multiple fibres to represent the same ligament Fig. . FurtherAccuracy: Representing complex 3D tissue geometries with virtual fibre paths introduces several sources of error. Significant uncertainty in reported ligament lengths originates from both the identification of the tissue attachment footprints and virtual fibre insertion sites within the footprint.Difficult to determine slack length: The resting length of ligaments cannot be measured using fluoroscopy. Therefore, while relative elongation patterns can be reported, true tissue strain patterns or loading conditions cannot be quantified. To circumvent this issue, many researchers define the reference length of a structure to be its length at e.g. full knee extension,Measurement frequency and radiation exposure: Fluoroscopes can generate either continuous Limited FOV: Traditional fluoroscopy systems are stationary with fields of view of 20-30 cm diameter. Thus, for many joints it is impossible to image complete activity cycles such as walking, running, or stair ascent/descent. Therefore, movements such as single legged lunge are often studied as the knee remains within the FOV.181Despite the many advantages of the virtual elongation method, there are also several limitations:The virtual fibre elongation method has demonstrated great potential for assessing the function of ligaments in healthy66Currently, the virtual fibre elongation method is too time consuming for clinical translation due to the segmentation of the joint anatomy, definition of ligament attachment points, and 2D/3D images registration steps. Introducing artificial intelligence techniques to automate these processes could eliminate the time-consuming nature of this method, and therefore make it clinically viable. For example, a segmentation method combining image registration and machine learning has been developed to automatically segment the region of interest on ultrasound Ultrasound is a non-invasive, radiation-free, and cost-effective technique to visualise the internal architecture of musculoskeletal soft tissues. Clinically, ultrasound is commonly used to identify pathological tendon abnormalities.97Typical ultrasound systems consist of a hand-held transducer connected by flexible wire to a cart that houses the electronics for signal generation and processing, as well as a screen for visualization. The working principle behind ultrasound imaging relies on propagating ultrasonic waves  into the tissue of interest and recording their reflection.38Two primary techniques have been developed to measure soft tissue strain during dynamic movements using ultrasound, myotendinous junction (MJ) tracking Fig.  and specFor both strain measurement techniques, the ultrasound transducers must be fixed to the body during dynamic movement to image a tissue. Typically, the ultrasound transducer is housed in a foam orthotic and strapped to the body using athletic tape.The MJ tracking technique enables muscle and tendon lengths to be quantified by tracking anatomical landmarks in each ultrasound image of a series collected throughout an activity. For example, the elongation of the free AT can be measured by tracking the displacement between the calcaneus attachment and the soleus-AT myotendinous junction (sATMJ).Speckle tracking provides an alternative method to quantify regional tissue strain using ultrasound. A speckle is an interference pattern with bright and dark spots in B-mode or radiofrequency (RF) ultrasound images.134Ultrasound provides two opportunities to assess the slack length of a tissue. Firstly, a tissue can be imaged at multiple joint postures until buckling can be identified in the B-mode images. This has been demonstrated on the patellar tendon.65in vivo AT strains during dynamic activities such as running (3.5-5.8%), walking (4.6%), and one-legged hopping (8-8.3%).in vivo AT strains during one-legged hopping are surprisingly close to the AT failure strains found in in vitro tendon tensile tests.in vivo and in vitro strain measurements and perhaps inconsistency among the methods. Secondly, the in vivo strain data from ultrasound measurements can serve as a variable to assess other parameters associated with AT injury, such as the mechanical “safe factor” 0 and “core temperature” 9 of the AT. Franz and co-workers measured the regional deformations of AT during walking,39Ultrasound based strain measurements have provided many important insights into the dynamic function of the AT. For example, ultrasound was used to quantify Ultrasound evaluations have also contributed towards understanding the function of human triceps surae muscles during walking and running.The application of ultrasound to quantify ligament strain is limited to a few studies investigating superficial ligaments during static movements, such as the dorsal lisfranc ligament,Ultrasound provides several key advantages over other methods for assessing musculoskeletal soft tissue strain. Firstly, it is non-invasive, relatively inexpensive, and does not expose the subjects to radiation. Secondly, ultrasound can dynamically image soft tissues, which enables regional deformation within the tissue to be quantified. Finally, it enables the strains of muscle fibres and tendon to be independently measured as it can differentiate muscle-tendon interfaces.Controversial reliability: Establishing good reliability of ultrasound tissue length measurement is fundamental to highly accurate measurements of tissue strain.Challenging to measure ligament strains: Ultrasound is mostly used clinically to diagnose ligament injuries,Confounded by out-of-plane motion: The complexity of measuring the deformation of 3D soft tissues in planar 2D ultrasound images is another key limitation of ultrasound. MJ tracking and speckle tracking both require tracking landmarks or pixels in the 2D ultrasound image. Out-of-plane strains resulting from tissues bulging, rotating, or twisting may be missed or misinterpreted as in plane translation. Freehand 3D ultrasound addresses this limitation, but cannot be applied to dynamic movements because the transducer must be swept over the length of the tissue.128Transducer fixation over tissue: For ultrasound measurement of dynamic activities, the transducer must be fixed over the tissue of interest as any motion of the transducer relative to the body can cause measurement error. This requires that the transducer is strapped to the body which may alter natural movement patterns. Finally, dynamic measurements are typically limited to a treadmill to avoid moving the ultrasound cart over-ground with the subject.Despite these advantages, ultrasound methods also suffer from several limitations:in vivo,Ultrasound methods are currently the most clinically viable for assessing musculoskeletal soft tissue strains due to their non-invasive, non-radiative, and relatively low-cost nature. However, their 2D nature limits the accuracy and repeatability of this method. Freehand 3D ultrasound scanning has been developed to quantify the 3D AT deformation In vivo strain measurements have provided important insights into the mechanical function of musculoskeletal soft tissues, resulting in improved rehabilitative and surgical treatments in sports medicine. This review has presented three main state-of-the-art methodologies that enable quantification of soft tissue strain patterns during dynamic movements: implantable strain sensors, virtual fibre elongation, and ultrasound. Each methodology has provided key measurements that altered treatments and rehabilitation for musculoskeletal soft tissues. However, further innovations in the measurement technologies and their clinical implementation will be necessary to facilitate a data driven revolution to personalize sports medicine treatments.Each strain measurement technique has its own virtues and limitations in terms of safety, application, and accuracy Table . ImplantAssessment of soft tissue slack length remains significantly challenging for each strain measurement technique. The inflection point method has been well validated for determining ACL slack length with implantable strain sensors, but it is uncertain whether similar experiments can be replicated on other soft tissues. The virtual fibre method currently has no reported method for measuring slack length, but potentially could be coupled with ultrasound. Ultrasound can provide measurements of slack length through visualizing tissue buckling or using shear wave propagation,in vivo human musculoskeletal soft tissue strains during functional movements. However, several techniques have been used to measure in vivo strains in animal tissue (sonomicrometry,in vivo strains in human bone,in vivo loading in human tendons (fibre optic sensors,A key limitation of this study is that it only focused on measurement techniques that have been applied to measure in vivo strain measurements have improved clinical treatments for many musculoskeletal pathologies including ACL reconstruction, AT repair, and TKA. However, a new generation of clinically viable technologies are needed to facilitate a data driven progression of personalized surgical and rehabilitative sports medicine treatments.In conclusion, we have found


Cerebral ischemia may cause irreversible neural network damage and result in functional deficits. Targeting neuronal repair after stroke potentiates the formation of new connections, which can be translated into a better functional outcome. Innate and adaptive immune responses in the brain and the periphery triggered by ischemic damage participate in regulating neural repair after a stroke. Immune cells in the blood circulation and gut lymphatic tissues that have been shaped by immune components including gut microbiota and metabolites can infiltrate the ischemic brain and, once there, influence neuronal regeneration either directly or by modulating the properties of brain-resident immune cells. Immune-related signalings and metabolites from the gut microbiota can also directly alter the phenotypes of resident immune cells to promote neuronal regeneration. In this review, we discuss several potential mechanisms through which peripheral and brain-resident immune components can cooperate to promote first the resolution of neuroinflammation and subsequently to improved neural regeneration and a better functional recovery. We propose that new insights into discovery of regulators targeting pro-regenerative process in this complex neuro-immune network may lead to novel strategies for neuronal regeneration. Stroke is one of the leading causes of functional deficits and death for aged populations. The lack of blood flow in ischemic conditions causes irreversible damage to neurons, and this disrupts the functioning of many neuronal networks. As a result, more and more attention has been paid in searching for therapies that can promote neuroplasticity. SVZ (subventricular zone) and SGZ (subgranular zone) are important areas for the proliferation of NPCs . The robustly increased proliferation of NPCs in these areas serves as the first step of neurogenesis after an ischemic stroke, and then newly generated neuroblasts migrate to the peri-infarct area, differentiate into mature neurons, and finally are able to compensate for the damaged neural network . Axonal Previous studies have mainly focused on promoting neuroplasticity through growth factors and neurotrophic factors. These growth factors and neurotrophic factors also have immunomodulatory effects. Neurotrophic factors from NGF (nerve growth factor), GDNF , and BDNF (brain-derived neurotrophic factor) may attenuate the neurotoxic inflammatory response after a stroke . The braThere is evidence pointing to the existence of communications between immune components in brain and peripheral circulation, and thus, it may be possible to target these systemic immune responses as a way of influencing the stroke outcome. Following cerebral ischemia and reperfusion damage, resting microglia are activated and release chemo-attractive cytokines; this allows the infiltration of peripheral myeloid cells through the disrupted blood–brain barrier and initiates the innate stage of immune response . After t+ Mo/MΦ are mainly located in the ischemic core and can be switched into alternatively active CX3CR1+ Mo/MΦ in the subacute and chronic phase, while CX3CR1+ Mo/MΦ mainly surround the ischemic area -dependent mechanism and their numbers peak at day 3 to day 4 after stroke . The twomic area . The lonmic area , 13. Howmic area . These cmic area , 16. CCLmic area . The funmic area . Mo/MΦ amic area . CollectIn stroke models, it has been demonstrated that immune components in both the brain and periphery can communicate and contribute to the expansion of Treg cells, leading to a long-term immunomodulatory effect after stroke . The masAfter a stroke, DAMPs (damage-associated molecular patterns) released from cellular debris cause IL-23 secretion from microglia and macrophage via TLRs (Toll-like receptors), and then brain-resident microglia, infiltrating Th17 cells, and γδ T cells activated by IL-23 can release the neurotoxic inflammatory cytokines . NF-κB aHowever, there is evidence to suggest pro-inflammatory cytokines in contrast to their detrimental effects may also be a positive regulator of neuroplasticity. Elevated levels of IL-6 and TNF-α in the spinal cord after stroke upregulate the concentrations of GAP-43 (growth-associated protein 43), NT-3 (neurotrophin-3), and BDNF, all of which are known to be involved in spinal axonal plasticity and lead to better spontaneous post-stroke recovery . After n+ T cells migrate to meninges and control the balance between M1 and M2 microglia/macrophage after ischemic injury . Gut microbiota are important potential mediators of adult neurogenesis after stroke, as evidenced by SCFA-enriched fecal microbiota transplantation or butyric acid supplement, which have both been able to promote neurological recovery . SCFAs cMicroglia are the brain-resident macrophages that function as the first immune responder and are also important contributors to the repair of damaged neural networks in ischemic brain. A recent study has demonstrated that efficient regeneration of damaged axons involves necroptosis of pro-inflammatory microglia followed by a repopulation of anti-inflammatory and pro-regenerative microglia . The celAlthough astrocytes are not considered as typical brain-resident immune cells, they also show regulatory functions in both the innate and adaptive immune response . FollowiFollowing ischemic injury, immune system, and related signaling may interact to promote the activation and polarization of microglia, and this process plays a crucial role in post-stroke neural repair. The intense pro-inflammatory stimulus in the microenvironment after a stroke activates microglia and upregulates M1 microglial TREM1 expression through NF-κB . IncreasAstrocytes can both respond to and regulate neuroinflammation. MAPK, NF-κB, and the STAT3 pathways are considered shared mediators of the astrocytic immune response . Accumul+ glia scar  is a master gatekeeper of neural inflammation. By suppressing NF-κB -mediated inflammation, PPARγ ameliorates the ischemic injury and attempts to prevent neural cell death . PPARγ sToll-like receptors are present on both immune cells and neural cells including microglia, astrocytes, and oligodendrocytes; they provide a link between the immune and central nervous systems. The neuroinflammatory response after cerebral ischemia activates the microglia-mediated TLR signaling, and this subsequently increases the release of inflammatory cytokines and exacerbates neural damage in the acute phase of stroke . The negThe receptor of SCFA has been demonstrated to exist on the surface of microglia, which means that SCFA can influence the function of microglia. Through SCFA receptor signaling and HDAC (histone deacetylase) inhibition, SCFAs can modulate immune homeostasis in gut, peripheral immune system, and brain . SupplemAs discussed in the above sections, crosstalk between brain-resident and peripheral immune system presents an increasingly attractive target for developing neural repair strategies. Investigations aim at finding repair-promoting therapies targeting brain–peripheral immunological interactions were mainly conducted in two perspectives: One is downregulating the detrimental pro-inflammatory responses and downstream pro-apoptotic cascades caused by this interaction, which can protect the newly generated and uninjured brain tissue. The other is upregulating levels of anti-inflammatory factors to facilitate debris clearance, growth factor release, and finally the activation of neuroplasticity-related pathways by cooperation of infiltrated and brain-resident immune cells. Preliminary studies have suggested that pharmacological strategies targeting this crosstalk can create a favorable immune microenvironment and finally lead to better clinical outcomes .Anti-inflammatory agents were proved to be beneficial for neurological recovery in clinical trials. They can directly counteract the neurotoxic inflammatory responses of brain-resident immune cells or alleviate neuroinflammation by shaping peripheral immune components. Fingolimod (FTY720) is now applied in the treatment for multiple sclerosis, and the therapeutic effects can be attributed to the inhibition of inflammatory T-lymphocyte infiltration . In expeBone marrow mononuclear cells (BMNCs) are composed of heterogeneous populations of hematopoietic lineage cells, stem cells, progenitor cells, as well as mesenchymal stromal cells. BMNCs promote neural stem cell proliferation and exert regulatory effects in immunological interactions between infiltrated and brain-resident cells , 137. ThThe emerging role of the gut–immune–brain axis in stroke recovery has been investigated in several preclinical studies by fecal microbiota transplantation or metabolite supplement. As a result, targeting gut microbiota provides a new perspective for stroke therapy and needs to be clarified by clinical studies. Existing evidence from completed studies shows that compared with healthy control, stroke patients showed a reduction in SCFA production-related gut microbiota ; dysbiosin vivo imaging methods. The immunoregulatory functions of these therapies were initially demonstrated by markers showing alterations in peripheral immune responses. Recent studies show that the activation state of brain-resident and infiltrated immune cells can also be visualized by medical imaging techniques  in existing studies; whether the improved neurological outcomes were gained by functional compensation or neural regeneration still requires verification through chniques , 143, soNeural repair processes including neurogenesis and axonal growth provide an important anatomical structure for functional reorganization and promoting recovery after an ischemic stroke. There is convincing evidence to suggest that the immune responses induced by ischemic injury can shape the microenvironment and alter the positive and negative regulators of neuronal repair. Immune cells, the cytokines and chemokines that they secrete, and immune-related ligands not only may directly regulate neuronal regeneration but also may act indirectly via their interactions with brain-resident immune cells. As a result, therapies targeting the immune responses after stroke seem to be feasible. However, in the contemporary stage, we can only establish an associative rather than causal link between immune responses and post-stroke neuronal repair, and further mechanistic researches are required to gain a comprehensive understanding of this neuro-immune crosstalk. As brain-infiltrated immune cells did not simply originate from passive diffusion of immune cells in peripheral circulation, one important direction for future studies is to find out upstream regulators of immune cell infiltration and their repair-associated phenotype transition. However, immune responses triggered by these infiltrated cells cannot be simply regarded as regenerative or destructive ones. It is important to boost proper repair-promoting immune responses at a proper time course during recovery. For example, depletion of monocytes at an early stage can reduce neural damage and promote neurogenesis after stroke, but this abolishment of monocytes hinders long-term functional recovery after stroke. Monocyte-derived macrophages share many similar properties with CNS-resident microglia, which poses a challenge to explore their respective roles during stroke recovery. Hence, studies about distinguishing monocyte-derived macrophages from brain-resident immune cells through high-throughput sequencing like single-cell RNA-Seq or through transgenic models deserve to be carried out in the future.Preliminary studies suggest that gut microbiota and metabolites influence stroke recovery through immunological mechanisms. Gut microbiota and metabolites can directly regulate immune cells from gut, which can then migrate to the ischemic brain and participate in neural damage and repair processes. They also play a pivotal role in regulating permeability of gut barrier and further influence immune responses triggered by translocated microbiota or metabolites in peripheral circulation. Furthermore, they also possess the ability to alter the responses of glia cells in the central nervous system, potentially endowing these cells with neuronal repair regulating functions. However, the ways that these changes in microbiota composition after a stroke influence CNS neurogenesis and axonal growth need to be further clarified and verified through germ-free or fecal microbiota transplantation mouse models in future studies. The efficacy of fecal microbiota transplantation and supplement of probiotics or dietary fiber to stroke patients also need to be tested in clinical practice. Collectively, one can speculate that these communications between peripheral and the brain-resident immune system may represent a new therapeutic approach for reducing the neural damage and promoting the neuronal repair that occurs after a stroke.FL has drafted the manuscript. XC, SZ, and CL have provided editing and writing assistance. JJ, XZ, and ZL have revised it critically for important intellectual content. CZ has approved the final version to be published. All authors have made substantial contributions to this manuscript, contributed to the writing of the manuscript, and read and approved the final manuscript.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.


Previous findings have suggested that the cortex involved in walking control in freely locomotion rats. Moreover, the spectral characteristics of cortical activity showed significant differences in different walking conditions. However, whether brain connectivity presents a significant difference during rats walking under different behavior conditions has yet to be verified. Similarly, whether brain connectivity can be used in locomotion detection remains unknown. To address those concerns, we recorded locomotion and implanted electroencephalography signals in freely moving rats performing two kinds of task conditions . The Granger causality method was used to determine brain functional directed connectivity in rats during these processes. Machine learning algorithms were then used to categorize the two walking states, based on functional directed connectivity. We found significant differences in brain functional directed connectivity varied between upslope and downslope walking. Moreover, locomotion detection based on brain connectivity achieved the highest accuracy (91.45%), sensitivity (90.93%), specificity (91.3%), and F1-score (91.43%). Specifically, the classification results indicated that connectivity features in the high gamma band contained the most discriminative information with respect to locomotion detection in rats, with the support vector machine classifier exhibiting the most efficient performance. Our study not only suggests that brain functional directed connectivity in rats showed significant differences in various behavioral contexts but also proposed a method for classifying the locomotion states of rat walking, based on brain functional directed connectivity. These findings elucidate the characteristics of neural information interaction between various cortical areas in freely walking rats. Brain connectivity effectively describes information flow (including direction and strength) between cortical areas , which cPrevious studies have revealed that the cortex plays a critical role in walking control in freely walking rats ,14 insteIn rodent models, brain network analysis is mainly used to study changes in connectivity during the evolution of diseases, such as epilepsy , depressAs earlier described, our knowledge of brain connectivity properties in rats performing walking locomotion tasks remains limited despite the wise use of rodent models in neuroscience. This study aimed to investigate differences in the brain connectivity of rats in different walking locomotion states. To address this problem, we recorded the locomotion states and implanted electroencephalography (EEG) signals in freely moving rats performing two kinds of natural task conditions . Although functional connectivity can measure the temporal synchronization correlation between active brain regions, effective connectivity indicating how the activity of one region influences other separate regions provides more information, to be more suitable to explore the variability of the brain connectivity in freely walking rats. Currently, in neuroscience, Granger causality is the most popular algorithm for extracting directional transmission information between brain regions . It can In this study, previous EEG data on four male Sprague–Dawley rats (aged 8–10 weeks and weighing 200–250 g) were used to examine differences in brain connectivity in rats in different locomotion states . Two typPreprocessing of EEG data was performed using EEGLAB 14.1.2b functions . First, Ultimately, to better explore the difference in brain effective connectivity in rats walking on different locomotion terrains, the EEG data were divided into four major sub-bands: the alpha band (7–13 Hz), beta band (13–30 Hz), low gamma band (30–50 Hz), and high gamma band (50–100 Hz). The filter used in this study is zero-phase finite impulse response filter in EEGLAB, whose design method is two-way least-squares. The present study investigated variations in brain connectivity in the full-frequency band (7–100 Hz) and four sub-band signals.x and y is included, the prediction of y is better than the prediction of y solely based on the past information of y. That is, if the variable x can help predict the future variable y, the variable x is considered to be the “Granger cause” of the variable y [x(t) and y(t) respectively represent the EEG signals from the two electrodes. They can be described as the following formula according the bivariate autoregressive model [p is the order, and xyu(t) and yxu(t) are the residuals associated with the models of x(t) and y(t), respectively. In this study, the selection of p is based on the AIC criteria and the validation of the bivariate autoregressive model is based on the Ljung-Box test. The Granger causality algorithm was utilized to compute brain connectivity in this study. Notably, our brain connectivity analysis mainly discussed functional directed characteristics. Therefore, in this study, the brain connectivity is more appropriately called “functional directed connectivity” rather than “effective connectivity”. The electrodes on the rat skull surface acted as nodes of connectivity EEG signals recorded by each electrode reflects the activities of neurons in the brain area below and nearby . Thus, triable y . In the ve model ,30:(1)x(var(.) is the variance over time, and x|x,y is the prediction of x(t) by the past samples of values of x(t) and y(t).The residuals then depend on the past values of both signals, and their variances arey to x (predicting x from y) isTherefore, Granger causality from In the current study, the Hermes toolbox was used to calculate the matrix formed by the brain functional directed connectivity, based on its built-in Granger causality algorithm from EEG data . The obtIn this study, three kinds of popular classifiers were used in locomotion state detection: KNN, RF, and SVM. KNN classifies samples based on measuring the distance between different feature values . The corWe calculated the functional directed connectivity matrix between all pairs of electrodes (32 × 32 = 1024 connections), obtaining 1024 connectivity metrics per locomotion state. The strength of the connection between an electrode and itself was zero and thus could not provide effective features for the classifier. Consequently, we removed them from the connectivity metrics, finally obtaining 992 (1024−32 = 992 connections) dimensional classification features. In this study, the dimension of EEG features was 19,200 . In this study, we selected four evaluation metrics  widely used in machine learning, to evaluate the detection effect of rats locomotion states . AccuracLinear mixed-effects models (using the MATLAB function “fitlme”) were used to test for the presence of significant differences in brain functional directed connectivity for different locomotion states. Because the connectivity measures that comes from different rats are independent non-identically distributions, they are not suitable for the General Linear Model. The linear mixed-effects model can only consider fixed effects and remove random effects . TherefoWe first identified variations in brain functional directed connectivity in the full-frequency band (7–100 Hz) in rats walking on different terrains. We found a significant difference in functional directed connectivity between different locomotion states. Specifically, compared with downslope-walking, the connectivity increased significantly when rats in upslope-walking, including larger-degree nodes, more connected edges, and greater connection weights a. The moAt the network level, the brain network indexes showed a considerable difference between upslope and downslope walking. In upslope walking, the brain network exhibited an increased global efficiency a. AnalogWe next explored the difference in brain functional directed connectivity in four major sub-bands—the alpha band (7–13 Hz), beta band (13–30 Hz), low gamma band (30–50 Hz), and high gamma band (50–100 Hz)—between rats in two locomotion states. Significant differences in brain functional directed connectivity for each sub-band were determined between upslope-walking and downslope-walking rats. In the alpha and low gamma bands, connections  in the upslope state increased relative to those in the downslope state a,c; incrAt the network level, the brain network indexes showed striking differences in alpha, beta, and low gamma bands for upslope and downslope walking. By contrast, the global efficiency and transitivity of the brain network in the alpha and low gamma bands were greater in upslope-walking rats than in the downslope-walking ones a,b. NotaIn this study, we used three kinds of classification algorithms to detect rat locomotion states and recorded the results for each classifier. To explore the altered connections in different frequency bands when rats were in different locomotion states, the classifiers were applied in the alpha, beta, low gamma, high gamma, and full bands. We recorded the results for the different classifiers in different frequency bands via 10-fold cross-validation. Simultaneously, in evaluating the performance of classification characterized by connectivity, we used EEG signals as features to classify the motion states. The performances of the different classifiers characterized by EEG signals in different frequency bands are shown in Characterized by the functional directed connectivity in different bands, the performances achieved using different classifiers are shown in Although rodents are often used in neuroscience research, our knowledge of brain connectivity properties in walking rats remains limited. In the present study, we investigated the difference in brain functional directed connectivity in rats during different locomotion states and proposed a novel method based on brain functional directed connectivity for locomotion state detection. Results showed that brain functional directed connectivity showed a significant difference in the full-frequency band and each sub-band when the rats were in upslope and downslope locomotion. The classification results also indicated that the connectivity features of the high gamma band contained the best discriminative information with respect to locomotion detection in rats. These findings elucidate the characteristics of neural information interaction between various cortical areas in freely walking rats. Consequently, in the full-frequency band, brain functional directed connectivity exhibited an apparent difference between rats walking upslope and downslope . CompareThe results further showed that functional directed connectivity in the rat brain presented significant differences for each sub-band between the rats walking upslope and those walking downslope. In the alpha band, the rats in upslope locomotion showed greater brain network connectivity , compared with the rats in downslope locomotion a. MoreovBy contrast, in the beta band, the brain network in the rats performing downslope locomotion had more connections f. In addIn the low gamma band, the brain network of the rats in upslope locomotion had more connections, larger-degree nodes, and greater weights c. Prior Notably, in the high gamma band, the brain network in rats walking upslope and rats walking downslope both increased abundant connected edges d,h. CompWe subsequently determined whether machine learning algorithms can be used to classify locomotion in rats the difference in brain network connectivity. Previous studies suggested that effective connectivity measures carried critical information about the neural properties of cognition and behavior . MoreoveIn this study, we revealed the brain functional directed connectivity properties in rats during different walking locomotion states and verified the feasibility of locomotion detection in rats based on brain functional directed connectivity. The results indicated that the functional directed connectivity in the rat brain showed apparent differences in the full frequency band and each sub-band between rats in upslope and downslope walking. Moreover, the use of functional directed connectivity as the classification feature for locomotion detection achieved satisfactory performance. Specifically, the classification results indicated that the connectivity features of the high gamma band contained the best discriminative information with respect to locomotion detection in rats, and the SVM classifier exhibited the best performance. This finding can elucidate rodent walking and help advance the research in neuro-prosthetic limb control in brain–machine interfaces.


Density dependence in helminth establishment and heterogeneity in exposure to infection are known to drive resilience to interventions based on mass drug administration (MDA). However, the interaction between these processes is poorly understood. We developed a novel individual-based model for onchocerciasis transmission, EPIONCHO-IBM, which accounts for both processes. We fit the model to pre-intervention epidemiological data and explore parasite dynamics during MDA with ivermectin.Density dependence and heterogeneity in exposure to blackfly (vector) bites were estimated by fitting the model to matched pre-intervention microfilarial prevalence, microfilarial intensity and vector biting rate data from savannah areas of Cameroon and Côte d’Ivoire/Burkina Faso using Latin hypercube sampling. Transmission dynamics during 25 years of annual and biannual ivermectin MDA were investigated. Density dependence in parasite establishment within humans was estimated for different levels of (fixed) exposure heterogeneity to understand how parametric uncertainty may influence treatment dynamics. Stronger overdispersion in exposure to blackfly bites results in the estimation of stronger density-dependent parasite establishment within humans, consequently increasing resilience to MDA. For all levels of exposure heterogeneity tested, the model predicts a departure from the functional forms for density dependence assumed in the deterministic version of the model.This is the first, stochastic model of onchocerciasis, that accounts for and estimates density-dependent parasite establishment in humans alongside exposure heterogeneity. Capturing the interaction between these processes is fundamental to our understanding of resilience to MDA interventions. Given that uncertainty in these processes results in very different treatment dynamics, collecting data on exposure heterogeneity would be essential for improving model predictions during MDA. We discuss possible ways in which such data may be collected as well as the importance of better understanding the effects of immunological responses on establishing parasites prior to and during ivermectin treatment. Onchocerca volvulus, is transmitted via the bites of Simulium blackflies. The World Health Organization has proposed onchocerciasis elimination in African countries by 2020/2025. Processes regulating parasite abundance in the lifecycle of helminths are known to influence the endemic prevalence in mathematical models. For example, when transmission intensity is low, a high proportion of incoming parasites may establish within a human host, whilst the opposite may be true when transmission intensity is high, possibly due to immunological processes. These processes may interact with exposure as some people are bitten more than others and receive more parasites. Therefore, regulatory processes that depend on parasite density and inter-individual variation in exposure play a central role in the ability of transmission to bounce back following mass drug administration. The former, because they may increase the success of parasite establishment as treatment progresses; the latter, because a few highly infected individuals may maintain transmission. We developed an individual-based model for onchocerciasis transmission and show that the interaction between these two processes impacts treatment outcomes. We highlight the need to obtain data on exposure to vector bites and to understand how immunological processes potentially regulating parasite establishment change under treatment.Onchocerciasis, caused by the helminth parasite  The World Health Organization (WHO)’s roadmap on neglected tropical diseases  has earmATP = L3 × ABR, the number of L3 larvae potentially received per person per year, where L3 is the mean number of L3 larvae in the fly population and ABR is the annual biting rate (the average number of bites received per person per year)). This decreasing proportion of establishing parasites with increasing ATP has implications for parasite resilience during mass drug administration  kE as 1 oNCHOSIM)  of annuaNCHOSIM) , movemenO. volvulus and Loa Loa are at risk of severe adverse events  following treatment with ivermectin if harbouring heavy loiasis microfilaraemia [O. volvulus) or “test and not treat” (testing for L. loa) strategies have been proposed and trialled for control in areas co-endemic with onchocerciasis and loiasis [O. volvulus and L. loa and helminth species more generally is poorly understood . A particular advantage is the capacity to model individual-based interventions. For example, individuals co-infected with laraemia . Consequ loiasis . EPIONCH(but see ).O. volvulus parasites—and heterogeneity in individual human exposure shape both the relationships between microfilarial prevalence, microfilarial intensity and ABR, and the resilience of onchocerciasis to MDA with ivermectin. In future, EPIONCHO-IBM will be used to model the control and elimination of onchocerciasis using current and alternative interventions, including the use of anti-Wolbachia therapies [O. volvulus. Combined with more statistically advanced approaches for estimating the parameters of individual-based models [In conclusion, we have developed a novel individual-based stochastic onchocerciasis transmission model, EPIONCHO-IBM, based on the well-established deterministic analogue, EPIONCHO. We have used EPIONCHO-IBM to better understand how density-dependent processes—in particular the density-dependent establishment of newly acquired herapies , moxidecherapies , ground-herapies  and new herapies . Our word models , and fitS1 TextA) Formal description of EPIONCHO-IBM. B) Uncertainty and sensitivity analyses using the Latin hypercube parameter sets.(DOCX)Click here for additional data file.


Loneliness and social isolation are common sources of chronic stress in modern society. Epidemiological studies have demonstrated that loneliness and social isolation increase mortality risk as much as smoking or alcohol consumption and more than physical inactivity or obesity. Loneliness in human is associated with higher blood pressure whereas enhanced atherosclerosis is observed in animal models of social isolation. Loneliness and social isolation lead to activation of the hypothalamic-pituitary-adrenocortical (HPA) axis, enhanced sympathetic nerve activity, impaired parasympathetic function and a proinflammatory immune response. These mechanisms have been implicated in the development of cardiovascular disease conferred by social isolation although a causal relationship has not been established so far. There is evidence that oxidative stress is likely to be a key molecular mechanism linking chronic psychosocial stress to cardiovascular disease. NADPH oxidase-mediated oxidative stress in the hypothalamus has been shown to be required for social isolation-induced HPA axis activation in socially isolated rats. Oxidative stress in the rostral ventrolateral medulla is also a key regulator of sympathetic nerve activity. In the vasculature, oxidative stress increases vascular tone and promote atherogenesis through multiple mechanisms. Thus, preventing oxidative stress may represent a therapeutic strategy to reduce the detrimental effects of social stress on health.  •Loneliness and social isolation are common sources of chronic stress in modern society.•Loneliness and social isolation increase the risk of cardiovascular disease.•Oxidative stress is likely to be a key molecular mechanism linking chronic psychosocial stress to cardiovascular disease.•NADPH oxidase-mediated oxidative stress is required for social isolation-induced HPA axis activation.•In the vasculature, oxidative stress increases vascular tone and promote atherogenesis. The INTMental stress in modern human societies occurs largely during social interactions . In addi2There is clear evidence that strong social relationships increase the likelihood of survival  whereas 3Social isolation of experimental animals exacerbates atherogenesis. This has been shown in different atherosclerosis models. Individual housing of cynomolgus monkeys on an atherogenic diet increases atherosclerosis development in the coronary artery . Likewis4There is clear evidence that loneliness leads to activation of the HPA axis in humans ,28. The Activation of the HPA axis has also been observed in animal models of social isolation. Monogamous prairie voles build pair bonds with mating partners and are used as an animal model to study the consequences of pair bonding or partner loss . SeparatIn the vascular system, glucocorticoids can promote the development of hypertension and atherosclerosis by augmenting vasoconstriction, reducing endothelial nitric oxide (NO) production and enhancing oxidative stress. Glucocorticoids potentiate the effects of catecholamines and other vasoconstrictors on vascular smooth muscle cells ,39. In eIn addition to its role in blood pressure regulation, endothelial NO also represents a key anti-atherosclerotic factor . Thus, t5The findings on SNS activation in loneliness and social isolation is less consistent than the activation of the HPA axis ,28. ChroIn adult rats, chronic social isolation has been found to increase the plasma concentrations of both epinephrine and norepinephrine . Social A well balanced vagal system is important to prevent the detrimental effects of a SNS overactivation ,55. The It has been reported that social environment has an impact on HF-HRV . High HFRegulation of HF-HRV by social environment has also been shown in animal studies. Compared to socially paired prairie voles, voles suffer from social isolation have lower HF-HRV, both at baseline and in response to stress ,68. The 6Loneliness and social isolation in humans cause differentiated gene expression in circulating leukocytes leading to the so-called conserved transcriptional response to adversity (CTRA). The CTRA is characterized by up-regulation of proinflammatory genes and down-regulation of antiviral immunity-related genes resulting in enhanced inflammation and an impaired antiviral response ,69,70. LThe proinflammatory CTRA observed in individuals exposed to loneliness and social isolation is likely to be caused by the SNS activation rather than the HPA axis ,69. LoneRemarkably, the CTRA-induced proinflammatory monocytes can traffic into the brain, cause “sickness behaviors” and augment loneliness, creating a vicious cycle ,73. The Moreover, chronic psychosocial stress has been associated with elevated levels of circulating proinflammatory cytokines, particularly of IL-6. Socially less well connected individuals have higher IL-6 levels ,77.7HPA activation, SNS activation and inflammation and oxidative damage [Oxidative stress is a key molecular mechanism linking chronic psychosocial stress to cardiovascular disease . In socie damage .In the rat model of social isolation rearing, the animals are housed individually starting at the age of 21 days. The protein level of corticotropin-releasing factor in the hypothalamus and the concentration of adrenocorticotropic hormone in the plasma are increased after 4 weeks of isolation, whereas the increased corticosterone levels in plasma and saliva can be observed after 7 weeks . In contNOX are a family of reactive oxygen species (ROS)-generating enzymes . The enzInterestingly, the NOX2 induction by social isolation in the hypothalamus is prevented by apocynin treatment and absent in rats with p47phox mutation , suggestA second positive feedback mechanism may be the HPA axis itself. Although glucocorticoids have been shown to inhibit NOX-mediated ROS production in some cell types , dexametIn addition, a down-regulation of antioxidant enzymes may also contribute to the brain oxidative stress induced by social isolation ,86 altho8ROS stimulates central and peripheral SNS activity . The symThe sympathoexcitation induced by oxidative stress in the RVLM has been shown to play a crucial role in causing blood pressure elevation in a number of hypertension models, including obesity-induced hypertension , neurogeNADPH oxidases seem to play a key role in mediating RVLM oxidative stress. Bilateral microinjection of AngII into the RVLM leads to oxidative stress and blood pressure elevation . These eAlthough the role of RVLM oxidative stress in regulating SNS activity is clearly shown, it is yet still unknown whether this mechanism is involved in social isolation-induced SNS activation. In the rat model of social isolation rearing, increased NOX2 gene expression has been shown in specific brain areas: amygdala, hippocampus, nucleus accumbens and prefrontal cortex, but not striatum . NOX2 ex9Social isolation leads to oxidative stress in the vascular tissue . Higher Mechanistically, social isolation-induced vascular oxidative stress can be mediated by HPA axis, SNS activation, and inflammatory cells . The effSNS activation may also contribute to social isolation-induced vascular oxidative stress. Enhanced systemic oxidative stress has been observed in rats treated in vivo with the sympathetic neurotransmitter norepinephrine . Treatme10In addition to NADPH oxidase, increased ROS production by mitochondria also contributes to social isolation-induced oxidative stress . The mitThe exact mechanisms how mitochondrial ROS participate in social isolation-induced pathology are incompletely understood. It has been shown that mitochondrial ROS promote the production of proinflammatory cytokines such as IL-6 and TNF-α . Moreove11There is clear evidence that loneliness and social isolation impair cardiovascular health. The underlying mechanisms may include HPA activation, SNS hyperactivity, parasympathetic dysfunction and a proinflammatory immune response. Oxidative stress is the brain is required for the social isolation-induced HPA activation and is probably also involved in SNS activation. In the vasculature, oxidative stress impairs endothelial function and promotes atherosclerosis. Both in the central nervous system and in the peripheral, NOX2 seems to be a key superoxide producer mediating social isolation-induced oxidative stress. This, however, remains to be validated in future studies using transgenic animal models. Another point is that some mechanisms presented in the present review article are puzzled together from studies using different models. Whether these mechanisms apply to social isolation remains elusive.The authors declare that they have no conflicts of interest.