Peripheral Th17/Treg imbalance in elderly patients with ischemic stroke

T cell interactions with microglia in immune-inflammatory processes of ischemic stroke

The primary mechanism of secondary injury after cerebral ischemia may be the brain inflammation that emerges after an ischemic stroke, which promotes neuronal death and inhibits nerve tissue regeneration. As the first immune cells to be activated after an ischemic stroke, microglia play an important immunomodulatory role in the progression of the condition. After an ischemic stroke, peripheral blood immune cells (mainly T cells) are recruited to the central nervous system by chemokines secreted by immune cells in the brain, where they interact with central nervous system cells (mainly microglia) to trigger a secondary neuroimmune response. This review summarizes the interactions between T cells and microglia in the immune-inflammatory processes of ischemic stroke. We found that, during ischemic stroke, T cells and microglia demonstrate a more pronounced synergistic effect. Th1, Th17, and M1 microglia can co-secrete pro-inflammatory factors, such as interferon-γ, tumor necrosis factor-α, and interleukin-1β, to promote neuroinflammation and exacerbate brain injury. Th2, Treg, and M2 microglia jointly secrete anti-inflammatory factors, such as interleukin-4, interleukin-10, and transforming growth factor-β, to inhibit the progression of neuroinflammation, as well as growth factors such as brain-derived neurotrophic factor to promote nerve regeneration and repair brain injury. Immune interactions between microglia and T cells influence the direction of the subsequent neuroinflammation, which in turn determines the prognosis of ischemic stroke patients. Clinical trials have been conducted on the ways to modulate the interactions between T cells and microglia toward anti-inflammatory communication using the immunosuppressant fingolimod or overdosing with Treg cells to promote neural tissue repair and reduce the damage caused by ischemic stroke. However, such studies have been relatively infrequent, and clinical experience is still insufficient. In summary, in ischemic stroke, T cell subsets and activated microglia act synergistically to regulate inflammatory progression, mainly by secreting inflammatory factors. In the future, a key research direction for ischemic stroke treatment could be rooted in the enhancement of anti-inflammatory factor secretion by promoting the generation of Th2 and Treg cells, along with the activation of M2-type microglia. These approaches may alleviate neuroinflammation and facilitate the repair of neural tissues.

Research progress on immune-related therapeutic targets of brain injury caused by cerebral ischemia

Stroke is the second leading cause of death worldwide and a leading cause of disability. The innate immune response occurs immediately after cerebral ischemia, resulting in adaptive immunity. More and more experimental evidence has proved that the immune response caused by cerebral ischemia plays an important role in early brain injury and later the recovery of brain injury. Innate immune cells and adaptive cells promote the occurrence of cerebral ischemic injury but also protect brain cells. A large number of studies have shown that cytokines and immune-related substances also have dual functions of promoting injury, reducing injury, or promoting injury recovery in the later stage of cerebral ischemia. They can be an important target for treating cerebral ischemic recovery. Therefore, this study discussed the immune cells, cytokines, and immune-related substances with dual roles in cerebral ischemia and summarized the therapeutic targets of cerebral ischemia. To explore more effective methods to treat cerebral ischemia, promote the recovery of brain function, and improve the prognosis of patients.

MiR-24-3p enhances the Treg/Th17 balance to improve cerebral ischemic injury by suppressing acetyl-CoA carboxylase 1 expression

BACKGROUND

Targeting ACC1 (acetyl coenzyme A carboxylase 1) to restore the balance between T-helper 17 (Th17) cells and regulatory T cells (Tregs) through metabolic reprogramming has emerged as a promising strategy for reducing neuroinflammation following stroke. We examined the roles of potential miRNAs in regulating ACC1 expression in Tregs and treating ischemic stroke.

METHODS

The expression of miR-24-3p in CD4+T cells of mice was confirmed. Then the protective effects of Ago-24-3p in a mouse model of prolonged occlusion of the distal middle cerebral artery (dMCAO) were examined. We analyzed the infiltration of Tregs and CD3+T cells into the brain and evaluated the improvement of neurological deficits induced by Ago-24-3p using the Modified Garcia Score and foot fault testing.

RESULTS

Our investigation revealed that miR-24-3p specifically targets ACC1. Elevated levels of miR-24-3p have been demonstrated to increase the population of Tregs and enhance their proliferation and suppressive capabilities. Conversely, targeted reduction of ACC1 in CD4+T cells has been shown to counteract the improved functionality of Tregs induced by miR-24-3p. In a murine model of dMCAO, administration of Ago-24-3p resulted in a substantial reduction in the size of the infarct within the ischemic brain area. This effect was accompanied by an upregulation of Tregs and a downregulation of CD3+T cells in the ischemic brain region. In ACC1 conditional knockout mice, the ability of Ago-24-3p to enhance infiltrating Treg cells and diminish CD3+T cells in the ischemic brain area has been negated. Furthermore, its capacity to reduce infarct volume has been reversed. Furthermore, we demonstrated that Ago-24-3p sustained improvement in post-stroke neurological deficits for up to 4 weeks after the MCAO procedure.

CONCLUSIONS

MiR-24-3p shows promise in the potential to reduce ACC1 expression, enhance the immunosuppressive activity of Tregs, and alleviate injuries caused by ischemic stroke. These discoveries imply that miR-24-3p could be a valuable therapeutic option for treating ischemic stroke.

Th17 Cells and IL-17A in Ischemic Stroke

The neurological injury and repair mechanisms after ischemic stroke are complex. The inflammatory response is present throughout stroke onset and functional recovery, in which CD4 + T helper(Th) cells play a non-negligible role. Th17 cells, differentiated from CD4 + Th cells, are regulated by various extracellular signals, transcription factors, RNA, and post-translational modifications. Th17 cells specifically produce interleukin-17A(IL-17A), which has been reported to have pro-inflammatory effects in many studies. Recently, experimental researches showed that Th17 cells and IL-17A play an important role in promoting stroke pathogenesis (atherosclerosis), inducing secondary damage after stroke, and regulating post-stroke repair. This makes Th17 and IL-17A a possible target for the treatment of stroke. In this paper, we review the mechanism of action of Th17 cells and IL-17A in ischemic stroke and the progress of research on targeted therapy.

Identification of diagnostic signatures for ischemic stroke by machine learning algorithm

OBJECTIVE

Ischemic stroke (IS) is one of the major diseases threatening human health and survival and a leading cause of acquired mortality and disability in adults. The aim of this study was to screen diagnostic features of IS and to explore the characteristics of immune cell infiltration in IS pathogenesis.

METHODS

The microarray data of IS (GSE16561, GSE58294, GSE37587, and GSE124026) in the GEO database were merged after removing the batch effect. Then integrated bioinformatic analysis and machine-learning strategies were adopted to analyze the functional correlation and select diagnostic signatures. The WGCNA was used to identify the co-expression modules related to IS. The CIBERSORT algorithm was performed to assess the inflammatory state of IS and to investigate the correlation between diagnostic signatures and infiltrating immune cells.

RESULTS

Functional analysis of dysregulated genes showed that immune response-regulating signaling pathway and pattern recognition receptor activity were enriched in the pathophysiology of IS. The turquoise module was identified as the significant module with IS. By using Lasso and SVM-RFE learning methods, we finally obtained four diagnostic genes, including LAMP2, CR1, CLEC4E, and F5. The corresponding results of AUC of ROC prediction model in training and validation cohort were 0.954 and 0.862, respectively. The immune cell infiltration analysis suggested that plasma cells, resting and activated NK cells, activated dendritic cells, memory B cells, CD8+ T cells, naïve CD4+ T cells, and resting mast cells may be involved in the development of IS. Additionally, these diagnostic signatures might be correlated with multiple immune cells in varying degrees.

CONCLUSION

We identified four biologically relevant genes (LAMP2, CR1, CLEC4E, and F5) with diagnostic effects for IS, our results further provide novel insights regarding molecular mechanisms associated with various immune cells that related to IS for future investigations.

Update on the role of T cells in cognitive impairment

The central nervous system (CNS) has long been considered an immune-privileged site, with minimal interaction between immune cells, particularly of the adaptive immune system. Previously, the presence of immune cells in this organ was primarily linked to events involving disruption of the blood-brain barrier (BBB) or inflammation. However, current research has shown that immune cells are found patrolling CNS under homeostatic conditions. Specifically, T cells of the adaptive immune system are able to cross the BBB and are associated with ageing and cognitive impairment. In addition, T-cell infiltration has been observed in pathological conditions, where inflammation correlates with poor prognosis. Despite ongoing research, the role of this population in the ageing brain under both physiological and pathological conditions is not yet fully understood. In this review, we provide an overview of the interactions between T cells and other immune and CNS parenchymal cells, and examine the molecular mechanisms by which these interactions may contribute to normal brain function and the scenarios in which disruption of these connections lead to cognitive impairment. A comprehensive understanding of the role of T cells in the ageing brain and the underlying molecular pathways under normal conditions could pave the way for new research to better understand brain disorders. LINKED ARTICLES: This article is part of a themed issue From Alzheimer's Disease to Vascular Dementia: Different Roads Leading to Cognitive Decline. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.6/issuetoc.

AIM2 inflammasome: A potential therapeutic target in ischemic stroke

Ischemic stroke (IS) is a significant global public health issue with a high incidence, disability, and mortality rate. A robust inflammatory cascade with complex and wide-ranging mechanisms occurs following ischemic brain injury. Inflammasomes are multiprotein complexes in the cytoplasm that modulate the inflammatory response by releasing pro-inflammatory cytokines and inducing cellular pyroptosis. Among these inflammasomes, the Absent in Melanoma 2 (AIM2) inflammasome shows the ability to detect a wide range of pathogen DNAs, thereby triggering an inflammatory response. Recent studies have indicated that the aberrant expression of AIM2 inflammasome in various cells is closely associated with the pathological processes of ischemic brain injury. This paper summarizes the expression and regulatory role of AIM2 in CNS and peripheral immune cells and discusses current therapeutic approaches targeting AIM2 inflammasome. These findings aim to serve as a reference for future research in this field.

Ginkgo biloba extract promotes Treg differentiation to ameliorate ischemic stroke via inhibition of HIF-1α/HK2 pathway

The ischemic brain can dialogue with peripheral tissues through the immune system. Ginkgo biloba extract (EGb) was used to regulate various neurological disorders; however, the impact of EGb on ischemic stroke is still unclear. Here, we aimed to investigate whether immunomodulation has participated in the beneficial effects of EGb on ischemia/reperfusion (I/R) brain injury. Mice were orally administered with EGb once daily for 7 days before the induction of I/R. Neurobehavioral scores, infarct volume, and brain inflammation were determined. The proportion of CD4+ T cells was detected by flow cytometry. EGb significantly lowered neurobehavioral scores, infarct volume, and the level of inflammatory cytokines in I/R mice. Interestingly, EGb altered the proportion of CD4+ T cells, particularly increasing the proportion of Treg cells. Depletion of Treg cells weakened the neuroprotective effects of EGb on ischemic stroke; furthermore, EGb decreased the expression of HIF-1α and HK2 and promoted the differentiation of Treg cells in vitro. EGb suppressed the HIF-1α/HK2 signaling pathway to promote the differentiation of Treg cells and ameliorate ischemic stroke in mice. The expansion effect of EGb on Treg cells could be exploited as part of future stroke therapy.

Expression and Clinical Significance of microRNA-138-5p and TGF-β3 in Peripheral Blood of Patients With Ankylosing Spondylitis

STUDY DESIGN

Clinical study.

OBJECTIVE

Our work was aimed at exploring the expression and clinical significance of microRNA-138-5p (miR-138-5p) and Transforming Growth Factor-beta 3 (TGF-β3) in peripheral blood of patients with ankylosing spondylitis (AS).

METHODS

Forty-seven patients with AS were selected as the AS group, and the staging of the enrolled AS patients was based on the BASDAI score: <4 points were classified as the stable stage (stable group) and ≥4 points were classified as the active stage (active group). Forty-seven cases were selected from the same period of healthy physical examination in our hospital as the control group. miR-138-5p and TGF-β3 levels and disease activity factors in peripheral blood were measured in all patients.

RESULTS

Compared to healthy subjects, reduced miR-138-5p levels and increased TGF-β3 levels were found in AS patient. Even more, level of miR-138-5p was decreased and level of TGF-β3 was found to be increased in active disease stage of AS in comparison to inactive disease. Correlation analysis disclosed that miR-138-5p expression in peripheral blood of AS patients was negatively correlated with TGF-β3, HLA-B27, ESR, CRP, and BASDAI; serum TGF-β3 was positively correlated with HLA-B27, ESR, CRP, and BASDAI. The ROC curve analysis disclosed that miR-138-5p and TGF-β3 had certain diagnostic value for AS, and the combined detection could improve the clinical diagnostic capability of this disease.

CONCLUSION

miR-138-5p and TGF-β3 in peripheral blood of AS patients are potential biological markers for the diagnosis of AS and are expected to be new clinical diagnostic indicators.

Role of Crosstalk between Glial Cells and Immune Cells in Blood-Brain Barrier Damage and Protection after Acute Ischemic Stroke

Blood-brain barrier (BBB) damage is the main pathological basis for acute ischemic stroke (AIS)-induced cerebral vasogenic edema and hemorrhagic transformation (HT). Glial cells, including microglia, astrocytes, and oligodendrocyte precursor cells (OPCs)/oligodendrocytes (OLs) play critical roles in BBB damage and protection. Recent evidence indicates that immune cells also have an important role in BBB damage, vasogenic edema and HT. Therefore, regulating the crosstalk between glial cells and immune cells would hold the promise to alleviate AIS-induced BBB damage. In this review, we first introduce the roles of glia cells, pericytes, and crosstalk between glial cells in the damage and protection of BBB after AIS, emphasizing the polarization, inflammatory response and crosstalk between microglia, astrocytes, and other glia cells. We then describe the role of glial cell-derived exosomes in the damage and protection of BBB after AIS. Next, we specifically discuss the crosstalk between glial cells and immune cells after AIS. Finally, we propose that glial cells could be a potential target for alleviating BBB damage after AIS and we discuss some molecular targets and potential strategies to alleviate BBB damage by regulating glial cells after AIS.

Bystanders or not? Microglia and lymphocytes in aging and stroke

As the average age of the world population increases, more people will face debilitating aging-associated conditions, including dementia and stroke. Not only does the incidence of these conditions increase with age, but the recovery afterward is often worse in older patients. Researchers and health professionals must unveil and understand the factors behind age-associated diseases to develop a therapy for older patients. Aging causes profound changes in the immune system including the activation of microglia in the brain. Activated microglia promote T lymphocyte transmigration leading to an increase in neuroinflammation, white matter damage, and cognitive impairment in both older humans and rodents. The presence of T and B lymphocytes is observed in the aged brain and correlates with worse stroke outcomes. Preclinical strategies in stroke target either microglia or the lymphocytes or the communications between them to promote functional recovery in aged subjects. In this review, we examine the role of the microglia and T and B lymphocytes in aging and how they contribute to cognitive impairment. Additionally, we provide an important update on the contribution of these cells and their interactions in preclinical aged stroke.

Mild Cognitive Impairment Is Associated with Enhanced Activation of Th17 Lymphocytes in Non-Alcoholic Fatty Liver Disease

Patients with nonalcoholic fatty liver disease (NAFLD) may show mild cognitive impairment (MCI). The mechanisms involved remain unclear. The plasma concentrations of several cytokines and chemokines were measured in 71 NAFLD patients (20 with and 51 without MCI) and 61 controls. Characterization and activation of leukocyte populations and CD4⁺ sub-populations were carried out and analyzed by flow cytometry. We analyzed the cytokines released from CD4⁺ cell cultures and the mRNA expression of transcription factors and receptors in peripheral blood mononuclear cells. The appearance of MCI in NAFLD patients was associated with increased activation of CD4⁺ T lymphocytes, mainly of the Th17 subtype, increased plasma levels of pro-inflammatory and anti-inflammatory cytokines such as IL-17A, IL-23, IL-21, IL-22, IL-6, INF-γ, and IL-13, and higher expression of the CCR2 receptor. Constitutive expression of IL-17 was found in cultures of CD4⁺ cells from MCI patients, reflecting Th17 activation. High IL-13 plasma levels were predictive of MCI and could reflect a compensatory anti-inflammatory response to the increased expression of pro-inflammatory cytokines. This study identified some specific alterations of the immune system associated with the appearance of neurological alterations in MCI patients with NAFLD that could be the basis to improve and restore cognitive functions and quality of life in these patients.

Associations between serum cholesterol and immuno-phenotypical characteristics of circulatory B cells and Tregs

Blood lipids play a major role in the manifestation of cardiovascular diseases. Recent research suggested that there are connections between cholesterol levels and immunological alterations. We investigated whether there is an association between serum cholesterol levels (total, HDL, LDL) and immune cells (B cell and regulatory T cells [Tregs]). The analysis was based on data from 231 participants of the MEGA study in Augsburg, Germany, recruited between 2018 and 2021. Most participants was examined two different times within a time period of 9 months. At every visit, fasting venous blood samples were taken. Immune cells were analyzed immediately afterwards using flow cytometry. Using multivariable-adjusted linear regression models, the associations between blood cholesterol concentrations and the relative quantity of several B cell and Treg subsets were analyzed. We found that particularly HDL cholesterol concentrations were significantly associated to some immune cell subpopulations: HDL cholesterol showed significant positive associations with the relative frequency of CD25++ Tregs (as proportion of all CD4+CD25++ T cells) and conventional Tregs (defined as the proportion of CD25+CD127- cells on all CD45RA- CD4+ T cells). Regarding B cells, HDL cholesterol values were inversely associated with the cell surface expression of IgD and with naïve B cells (CD27- IgD+ B cells). In conclusion, HDL cholesterol levels were associated with modifications in the composition of B cell and Tregs subsets demonstrating an important interconnection between lipid metabolism and immune system. Knowing that this association exists might be crucial for a deeper and more comprehensive understanding of the pathophysiology of atherosclerosis.

The let-7b-5p, miR-326, and miR-125a-3p are associated with left ventricular systolic dysfunction in post-myocardial infarction

Background

Acute ST-elevation myocardial infarction (STEMI) can lead to adverse cardiac remodeling, resulting in left ventricular systolic dysfunction (LVSd) and heart failure. Epigenetic regulators, such as microRNAs, may be involved in the physiopathology of LVSd.

Objective

This study explored microRNAs in peripheral blood mononuclear cells (PBMC) of post-myocardial infarction patients with LVSd.

Methods

Post-STEMI patients were grouped as having (LVSd, n = 9) or not LVSd (non-LVSd, n = 16). The expression of 61 microRNAs was analyzed in PBMC by RT-qPCR and the differentially expressed microRNAs were identified. Principal Component Analysis stratified the microRNAs based on the development of dysfunction. Predictive variables of LVSd were investigated through logistic regression analysis. A system biology approach was used to explore the regulatory molecular network of the disease and an enrichment analysis was performed.

Results

The let-7b-5p (AUC: 0.807; 95% CI: 0.63-0.98; p = 0.013), miR-125a-3p (AUC: 0.800; 95% CI: 0.61-0.99; p = 0.036) and miR-326 (AUC: 0.783; 95% CI: 0.54-1.00; p = 0.028) were upregulated in LVSd (p < 0.05) and discriminated LVSd from non-LVSd. Multivariate logistic regression analysis showed let-7b-5p (OR: 16.00; 95% CI: 1.54-166.05; p = 0.020) and miR-326 (OR: 28.00; 95% CI: 2.42-323.70; p = 0.008) as predictors of LVSd. The enrichment analysis revealed association of the targets of these three microRNAs with immunological response, cell-cell adhesion, and cardiac changes.

Conclusion

LVSd alters the expression of let-7b-5p, miR-326, and miR-125a-3p in PBMC from post-STEMI, indicating their potential involvement in the cardiac dysfunction physiopathology and highlighting these miRNAs as possible LVSd biomarkers.

Regulatory T lymphocytes as a therapy for ischemic stroke

Unrestrained excessive inflammatory responses exacerbate ischemic brain injury and impede post-stroke brain recovery. CD4+CD25+Foxp3+ regulatory T (Treg) cells play important immunosuppressive roles to curtail inflammatory responses and regain immune homeostasis after stroke. Accumulating evidence confirms that Treg cells are neuroprotective at the acute stage after stroke and promote brain repair at the chronic phases. The beneficial effects of Treg cells are mediated by diverse mechanisms involving cell-cell interactions and soluble factor release. Multiple types of cells, including both immune cells and non-immune CNS cells, have been identified to be cellular targets of Treg cells. In this review, we summarize recent findings regarding the function of Treg cells in ischemic stroke and the underlying cellular and molecular mechanisms. The protective and reparative properties of Treg cells endorse them as good candidates for immune therapy. Strategies that boost the numbers and functions of Treg cells have been actively developing in the fields of transplantation and autoimmune diseases. We discuss the approaches for Treg cell expansion that have been tested in stroke models. The application of these approaches to stroke patients may bring new hope for stroke treatments.

Immunomodulation: The next target of mesenchymal stem cell-derived exosomes in the context of ischemic stroke

Ischemic stroke (IS) is the most prevalent form of brain disease, characterized by high morbidity, disability, and mortality. However, there is still a lack of ideal prevention and treatment measures in clinical practice. Notably, the transplantation therapy of mesenchymal stem cells (MSCs) has been a hot research topic in stroke. Nevertheless, there are risks associated with this cell therapy, including tumor formation, coagulation dysfunction, and vascular occlusion. Also, a growing number of studies suggest that the therapeutic effect after transplantation of MSCs is mainly attributed to MSC-derived exosomes (MSC-Exos). And this cell-free mediated therapy appears to circumvent many risks and difficulties when compared to cell therapy, and it may be the most promising new strategy for treating stroke as stem cell replacement therapy. Studies suggest that suppressing inflammation via modulation of the immune response is an additional treatment option for IS. Intriguingly, MSC-Exos mediates the inflammatory immune response following IS by modulating the central nervous system, the peripheral immune system, and immunomodulatory molecules, thereby promoting neurofunctional recovery after stroke. Thus, this paper reviews the role, potential mechanisms, and therapeutic potential of MSC-Exos in post-IS inflammation in order to identify new research targets.

Gut-brain axis: Mechanisms and potential therapeutic strategies for ischemic stroke through immune functions

After an ischemic stroke (IS) occurs, immune cells begin traveling to the brain and immune system from the gut and gastrointestinal tract, where most of them typically reside. Because the majority of the body's macrophages and more than 70% of the total immune cell pool are typically found within the gut and gastrointestinal tract, inflammation and immune responses in the brain and immune organs require the mobilization of a large number of immune cells. The bidirectional communication pathway between the brain and gut is often referred to as the gut-brain axis. IS usually leads to intestinal motility disorders, dysbiosis of intestinal microbiota, and a leaky gut, which are often associated with poor prognosis in patients with IS. In recent years, several studies have suggested that intestinal inflammation and immune responses play key roles in the development of IS, and thus may become potential therapeutic targets that can drive new therapeutic strategies. However, research on gut inflammation and immune responses after stroke remains in its infancy. A better understanding of gut inflammation and immune responses after stroke may be important for developing effective therapies. This review discusses the immune-related mechanisms of the gut-brain axis after IS and compiles potential therapeutic targets to provide new ideas and strategies for the future effective treatment of IS.

Effect of dexmedetomidine on postoperative cognitive dysfunction in elderly patients undergoing orthopaedic surgery: study protocol for a randomized controlled trial

AIMS

This trial aims to assess whether dexmedetomidine can reduce the incidence of postoperative cognitive dysfunction in elderly orthopaedic patients and explore the specific mechanism.

BACKGROUND

Postoperative cognitive dysfunction is a common complication after orthopaedic surgery that results in poor prognosis and increases the length of hospital stays and costs. Dexmedetomidine has been confirmed as a drug that can improve postoperative cognitive dysfunction in some studies. However, to date, the specific mechanism by which dexmedetomidine improves postoperative cognitive dysfunction is still elusive.

METHODS/DESIGN

A single-centre, prospective, double-blinded, randomized controlled trial will be conducted at Hebei General Hospital. Ninety-six elderly patients who undergo total hip or knee replacement will be studied in this trial and randomly divided into two groups. Patients in the experimental group will receive a loading dose of 0.5 μg/kg dexmedetomidine for 10 min and then a maintenance dose of 0.5 μg/kg/h dexmedetomidine until 30 min before the end of the operation, and patients in the control group will be infused with an equal volume of normal saline. The incidence of postoperative cognitive dysfunction will be the primary outcome. Changes in the balance of T helper 17 cell and regulatory T cell; the levels of matrix metalloproteinase 9, S-100β, IL-17A, and IL-10; perioperative complications; hospitalization duration; and intraoperative blood loss will be the secondary outcomes.

DISCUSSION

The consequences of this trial will show that dexmedetomidine can improve postoperative cognitive dysfunction in elderly orthopaedic patients, which may be related to the balance of T helper 17/regulatory T cells.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2200055802 . Registered on 20 January 2022.

Breast cancer tumor microenvironment affects Treg/IL-17-producing Treg/Th17 cell axis: Molecular and therapeutic perspectives

The tumor microenvironment (TME) comprises a variety of immune cells, among which T cells exert a prominent axial role in tumor development or anti-tumor responses in patients with breast cancer (BC). High or low levels of anti-inflammatory cytokines, such as transforming growth factor β, in the absence or presence of proinflammatory cytokines, such as interleukin-6 (IL-6), delineate the fate of T cells toward either regulatory T (Treg) or T helper 17 (Th17) cells, respectively. The transitional state of RORγt⁺Foxp3⁺ Treg (IL-17-producing Treg) resides in the middle of this reciprocal polarization, which is known as Treg/IL-17-producing Treg/Th17 cell axis. TME secretome, including microRNAs, cytokines, and extracellular vesicles, can significantly affect this axis. Furthermore, immune checkpoint inhibitors may be used to reconstruct immune cells; however, some of these novel therapies may favor tumor development. Therefore, understanding secretory and cell-associated factors involved in their differentiation or polarization and functions may be targeted for BC management. This review discusses microRNAs, cytokines, and extracellular vesicles (as secretome), as well as transcription factors and immune checkpoints (as cell-associated factors), which influence the Treg/IL-17-producing Treg/Th17 cell axis in BC. Furthermore, approved or ongoing clinical trials related to the modulation of this axis in the TME of BC are described to broaden new horizons of promising therapeutic approaches.

Fecal microbiota transplantation and replenishment of short-chain fatty acids protect against chronic cerebral hypoperfusion-induced colonic dysfunction by regulating gut microbiota, differentiation of Th17 cells, and mitochondrial energy metabolism

BACKGROUND

Little is known about the association between gut microbiota and intestinal injury under a state of chronic cerebral hypoperfusion (CCH). Here, the effects of gut microbiota and short-chain fatty acids (SCFAs), as important metabolic products, on intestinal function and potential mechanisms after CCH were investigated.

METHODS

Rats were subjected to bilateral common carotid artery occlusion (BCCAo) to induce CCH. The gut microbiota and metabolites of SCFAs were assessed by 16S rRNA sequencing and targeted metabolomics, respectively. Transcriptomic analysis of colon tissues was also conducted. Subsequently, potential molecular pathways and differentially expressed genes were verified by western blot, immunoprecipitation, and immunofluorescence analyses. Furthermore, the integrity of the colonic barrier was evaluated by hematoxylin and eosin and mucin 2 staining and expression levels of tight junction proteins. Besides, colonic inflammation was further assessed by flow cytometry and expression levels of inflammatory cytokines. In addition, colonic mitochondrial dysfunction was analyzed via membrane potential, reactive oxygen species, electron transport chain (ETC) activities, adenosine triphosphate content, and mitochondrial ultrastructure.

RESULTS

CCH modified gut microbial composition and microbial metabolism of SCFAs, which may be associated with inhibition of mitochondrial ETC activities and oxidative phosphorylation, leading to dysregulation of mitochondrial energy metabolism. Furthermore, CCH induced differentiation of pathogenic Th17 cells, promoted the formation of complexes of interferon regulatory factor 4 and signal transducer and activator of transcription 3 (STAT3), and increased the phosphorylation of STAT3. This was associated with an impairment of colonic barrier function and chronic colonic inflammation. In contrast, FMT and SCFA replenishment ameliorated CCH-induced gut microbial dysbiosis by increasing the intestinal content of Ruminococcus_sp_N15_MGS_57 and modulating microbial metabolism of SCFAs by increasing acetic acid contents associated with an improvment of the balance between Tregs and Th17 cells, mitochondrial ETC activities, and oxidative phosphorylation to prevent colonic inflammation and dysregulation of mitochondrial energy metabolism.

CONCLUSION

These findings indicate that FMT and SCFA replenishment present a promising therapeutic strategy against colonic dysfunction under a state of chronic cerebral ischemia.

Mechanism of Huangqi-Honghua combination regulating the gut microbiota to affect bile acid metabolism towards preventing cerebral ischaemia-reperfusion injury in rats

CONTEXT

Effective treatment of ischaemic stroke is required to combat its high prevalence and incidence. Although the combination of Astragalus membranaeus (Fisch.) Bge. (Fabaceae) and Carthamus tinctorius L. (Asteraceae) is used in traditional Chinese medicine for the treatment of stroke, its underlying mechanism remains unclear.

OBJECTIVE

The objective of this study is to elucidate the mechanism underlying Huangqi-Honghua (HQ-HH) for the treatment of ischaemic stroke by gut microbiota analysis and metabonomics.

MATERIALS AND METHODS

Sprague-Dawley rats were randomly assigned to the sham, model, HQ-HH, and Naoxintong (NXT) groups. The middle cerebral artery occlusion-reperfusion model was established after 7 days of intragastric administration in the HQ-HH (4.5 g/kg, qd) and NXT (1.0 g/kg, qd) groups. The neurological examination, infarct volume, gut microbiota, bile acids, and inflammation markers were assessed after 72 h of reperfusion.

RESULTS

Compared with the model group, HQ-HH significantly reduced the neurological deficit scores of the model rats (2.0 ± 0.2 vs. 3.16 ± 0.56), and reduced the cerebral infarct volume (27.83 ± 3.95 vs. 45.17 ± 2.75), and reduced the rate of necrotic neurons (26.35 ± 4.37 vs. 53.50 ± 9.61). HQ-HH regulating gut microbiota, activating the bile acid receptor FXR, maintaining the homeostasis of bile acid, reducing Th17 cells and increasing Treg cells in the rat brain, reducing the inflammatory response, and improving cerebral ischaemia-reperfusion injury.

CONCLUSIONS

These data indicate that HQ-HH combination can improve ischaemic stroke by regulating the gut microbiota to affect bile acid metabolism, providing experimental evidence for the wide application of HQ-HH in clinical practice of ischaemic stroke.

Th1/Th2 polarization of peripheral immune response in atherothrombotic and cardioembolic stroke: a prospective study

Compelling evidence suggest a key role of immune system in the development and progression of ischemic stroke. Although the balance between proinflammatory CD4 + T helper (Th)-1 lymphocytes, expressing T-bet transcription factor, and anti-inflammatory Th2 cells expressing GATA3 seems to influence the outcome in experimental stroke, the role of peripheral immune response in acute stroke patients is poorly understood. We aimed to evaluate the peripheral Th1/Th2 balance in acute atherothrombotic (ATHS) and cardioembolic stroke (CES) patients and in age- and sex-matched healthy subjects. Using flow cytometry, we analyzed the percentage of CD4 + T-bet + T cells and CD4 + GATA3 + T cells from peripheral blood of ATHS and CES patients (2,4 and 7 days after stroke onset). Patients and controls were screened for infectious conditions, autoimmune, inflammatory, or cancerous diseases. On day 2 circulating CD4 + T-bet + T cells were significantly higher in stroke patients compared to controls, and in ATHS compared to CES and controls. On day 7, we observed a significant increase of CD4 + T-bet + T cells in both ATHS and CES patients compared to baseline. No difference was observed in circulating CD4 + GATA3 + T cells among ATHS, CES patients, and controls. These data suggest that circulating CD4 + T-bet + T cells could be useful marker indicating atherothrombotic genesis of stroke and provide new insight into the peripheral adaptive immune response in acute stroke.

Investigation into the potential mechanism and molecular targets of Fufang Xueshuantong capsule for the treatment of ischemic stroke based on network pharmacology and molecular docking

Fufang Xueshuantong (FFXST) capsule is a traditional Chinese medicine (TCM) preparation used to activate blood circulation, resolve stasis, benefit qi, and nourish yin in clinical practice. However, its potential mechanism and molecular targets after ischemic stroke (IS) have not been investigated. The aim of this research was to investigate the molecular mechanisms of FFXST in the treatment of IS based on network pharmacology and molecular docking. We used the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) to collect candidate compounds of four herbs in FFXST; disease-related differential genes were screened using the Gene Expression Omnibus (GEO) database, and a compound–disease network was created using Cytoscape 3.8.2 software. The topological analysis of the protein–protein interaction (PPI) network was then created to determine the candidate targets of FFXST against IS. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted using the clusterProfiler package in R. The gene–pathway network of FFXST against IS was created to obtain the key target genes. Molecular docking was used to validate the core targets using AutoDock Vina 1.1.2. A total of 455 candidate compounds of FFXST and 18,544 disease-related differential genes were screened. Among them, FFXST targets for IS treatment had 67 active compounds and 10 targets in the PPI network related to STAT1, STAT3, and HIF1A. The biological processes of GO analysis included the regulation of reactive oxygen species metabolic process, cellular response to chemical stress, regulation of angiogenesis, regulation of vasculature development, positive regulation of cytokine production, and response to oxidative stress. The KEGG enrichment analysis showed that Kaposi sarcoma-associated herpesvirus infection, microRNAs in the cancer signaling pathway, Th17 cell differentiation, and HIF-1 signaling pathway were significantly enriched. The network pharmacology outcomes were further verified by molecular docking. We demonstrated that FFXST protection against IS may relate to the regulation of oxidative stress, immune inflammatory response, and angiogenesis through the relevant signaling pathways. Our study systematically illustrated the application of network pharmacology and molecular docking in evaluating characteristics of multi-component, multi-target, and multi-pathway of FFXST for IS.

Identification of circulating immune landscape in ischemic stroke based on bioinformatics methods

Ischemic stroke (IS) is a high-incidence disease that seriously threatens human life and health. Neuroinflammation and immune responses are key players in the pathophysiological processes of IS. However, the underlying immune mechanisms are not fully understood. In this study, we attempted to identify several immune biomarkers associated with IS. We first retrospectively collected validated human IS immune-related genes (IS-IRGs) as seed genes. Afterward, potential IS-IRGs were discovered by applying random walk with restart on the PPI network and the permutation test as a screening strategy. Doing so, the validated and potential sets of IS-IRGs were merged together as an IS-IRG catalog. Two microarray profiles were subsequently used to explore the expression patterns of the IS-IRG catalog, and only IS-IRGs that were differentially expressed between IS patients and controls in both profiles were retained for biomarker selection by the Random Forest rankings. CLEC4D and CD163 were finally identified as immune biomarkers of IS, and a classification model was constructed and verified based on the weights of two biomarkers obtained from the Neural Network algorithm. Furthermore, the CIBERSORT algorithm helped us determine the proportions of circulating immune cells. Correlation analyses between IS immune biomarkers and immune cell proportions demonstrated that CLEC4D was strongly correlated with the proportion of neutrophils (r = 0.72). These results may provide potential targets for further studies on immuno-neuroprotection therapies against reperfusion injury.

Some miRNA expressions and their targets in ischemic stroke

Ischemic stroke (IS) is a global health challenge leading to life-long disabilities or the deaths of patients. IS is a complex disease where genetic and environmental factors are both concerned with the pathophysiology of the condition. Here, we aimed to investigate various microRNA (miRNA) expressions and their targets in IS. A rapid and accurate diagnosis of acute IS is important to perform appropriate treatment. Therefore, there is a need for a more rapid and simple tool to carry out an acute diagnosis of IS. miRNAs are small RNA molecules serving as precious biomarkers due to their easy detection and stability in blood samples. The present systematic review aimed to summarize previous studies investigating several miRNA expressions and their targets in IS.

Longitudinal change of Th1, Th2, and Th17 cells and their relationship between cognitive impairment, stroke recurrence, and mortality among acute ischemic stroke patients

Background

T‐helper (Th) cells regulate immunity and inflammation, and modulate cognitive impairment in both cardio‐cerebrovascular and neurological diseases. This study aimed to explore the correlation of longitudinal change of Th1/2/17 cells with cognitive impairment and prognosis in acute ischemic stroke (AIS).

Methods

Th1/2/17 cells were detected by flow cytometry in peripheral blood samples from 150 AIS patients at admission (baseline), Day (D)1, D3, and D7 after admission, and from 30 controls. Mini‐Mental State Examination (MMSE) score among AIS patients at discharge was assessed. Stroke recurrence and mortality were evaluated.

Results

Th1 (p = 0.013) and Th17 cells (p < 0.001) but not Th2 cells (p = 0.105) were elevated in AIS patients versus controls. Th1 cells (p = 0.027) and Th17 cells (p < 0.001) but not Th2 cells (p = 0.227) were positively correlated with NIHSS score in AIS patients. Furthermore, Th1 and Th17 cells elevated from baseline to D3 and then decreased on D7 after AIS onset, while Th2 cells illustrated an opposite trend (all p < 0.001). Th17 cells on D1 (p = 0.011), D3 (p = 0.014), and D7 (p < 0.001) were correlated with lower MMSE score, and their levels on D3 (p = 0.033) and D7 (p = 0.004) were related to elevated cognitive impairment. Th1 and Th2 cells were not related to cognitive function (all p > 0.05). Additionally, Th17 cells at baseline, D1, D3, and D7 (all p < 0.05) were increased in recurrent patients versus non‐recurrent patients, and in survived patients versus dead patients, but Th1 or Th2 cells did not vary (all p > 0.05).

Conclusion

Th17 cells correlate with increased cognitive impairment, stroke recurrence, and mortality among AIS patients.

Inflammatory Responses After Ischemic Stroke

Ischemic stroke generates an immune response that contributes to neuronal loss as well as tissue repair. This is a complex process involving a range of cell types and effector molecules and impacts tissues outside of the CNS. Recent reviews address specific aspects of this response, but several years have passed and important advances have been made since a high-level review has summarized the overall state of the field. The present review examines the initiation of the inflammatory response after ischemic stroke, the complex impacts of leukocytes on patient outcome, and the potential of basic science discoveries to impact the development of therapeutics. The information summarized here is derived from broad PubMed searches and aims to reflect recent research advances in an unbiased manner. We highlight valuable recent discoveries and identify gaps in knowledge that have the potential to advance our understanding of this disease and therapies to improve patient outcomes.

CCL21 contributes to Th17 cell migration in neuroinflammation in obese mice following lead exposure

Obesity and lead exposure can independently cause neuroinflammation, which is associated with neurodegenerative diseases. Although Th17 cells play critical roles in inflammatory diseases of the central nervous system, few studies have evaluated their role in neuroinflammation in the background of obesity and lead exposure. In this study, the mechanism underlying inflammatory injury was evaluated in a mouse model of high fat diet-induced obesity following lead exposure. Neuroinflammation was aggravated in mice with obesity following lead exposure, and this was accompanied by increases in Th17 cells in the brain and IL-17A and IL-22 secretion. An antibody array using Z310, a choroid plexus epithelium cell line, revealed that CCL21 was the most highly altered chemokine. CCL21 expression was higher in the choroid plexus of obese mice treated with lead than in mice with obesity or lead treatment alone and was higher in Z310 cells treated with lead and palmitic acid. CCL21 knockout reduced chemotaxis. Our findings suggest that lead exposure can aggravate inflammation in brain tissues of obese mice, possibly by the CCL21-mediated regulation of the passage of Th17 cells through the blood-cerebrospinal fluid barrier. Our findings provide new insights into the mechanism underlying the combined effects of lead and obesity.

FOXO3a Alleviates the Inflammation and Oxidative Stress via Regulating TGF-β and HO-1 in Ankylosing Spondylitis

This study aimed to investigate whether Forkhead box O3a (FOXO3a) modulates inflammation and oxidative stress in ankylosing spondylitis (AS). We applied bioinformatics analysis, quantitative real-time polymerase chain reaction, immunoblotting, enzyme linked immunosorbent assay, chromatin immunoprecipitation, and dual-luciferase reporter assay. Gene overexpression and knockdown of FOXO3a were conducted via lentivirus and small interfering RNA, respectively. Downregulated FOXO3a expression was first confirmed in AS patients. Interleukin-8 (IL-8) and IL-17A were highly expressed and negatively related with FOXO3a in AS. Total antioxidant capacity (T-AOC) were markedly decreased and positively associated with FOXO3a in AS. Overexpression of FOXO3a inhibited the secretion of inflammatory cytokines and promoted the production of antioxidant enzymes in Jurkat cells. Transforming growth factor-β (TGF-β) and heme oxygenase 1 (HO-1), which had binding sites to FOXO3a based on bioinformatics analysis, were abnormally expressed and positively related with FOXO3a. Accordingly, FOXO3a obviously elevated the protein and transcription levels of TGF-β and HO-1 in Jurkat cells. The above results were verified by silencing FOXO3a. Moreover, FOXO3a directly interacted with and promoted the transcription of TGF-β and HO-1. In summary, the modulation of cellular inflammation and oxidative stress via FOXO3a-mediated TGF-β and HO-1 activation is partly involved in the pathogenesis of AS.

The Construction and Analysis of Immune Infiltration and Competing Endogenous RNA Network in Acute Ischemic Stroke

Acute ischemic stroke (AIS) is a common neurological disease that seriously endangers both the physical and mental health of human. After AIS, activated immune cells are recruited to the stroke site, where inflammatory mediators are released locally, and severe immune inflammatory reactions occur within a short time, which affects the progress and prognosis of IS. Circular RNA (circRNA) is a type of non-coding RNA (ncRNA) with a closed-loop structure and high stability. Studies have found that circRNA can affect the course of IS. However, there is no report on ceRNA’s pathogenesis in AIS that is mediated by circRNA. In this study, the CIBERSORT algorithm was used to analyze the distribution of immune cells in patients with AIS. mRNA dataset was downloaded from the GEO database, and the weighted gene co-expression network analysis (WGCNA) method was used to construct weighted gene co-expression to determine 668 target genes, using GO, KEGG enrichment analysis, construction of protein-protein interaction (PPI) network analysis, and molecular complex detection (MCODE) plug-in analysis. The results showed that the biological function of the target gene was in line with the activation and immune regulation of neutrophils; signal pathways were mostly enriched in immune inflammation-related pathways. A Venn diagram was used to obtain 52 intersection genes between target genes and disease genes. By analyzing the correlation between the intersection genes and immune cells, we found that the top 5 hub genes were TOM1, STAT3, RAB3D, MDM2, and FOS, which were all significantly positively correlated with neutrophils and significantly negatively correlated with eosinophils. A total of 52 intersection genes and the related circRNA and miRNA were used as input for Cytoscape software to construct a circRNA-mediated ceRNA competition endogenous network, where a total of 18 circRNAs were found. Further analysis of the correlation between circRNA and immune cells found that 4 circRNAs are positively correlated with neutrophils. Therefore, we speculate that there may be a regulatory relationship between circRNA-mediated ceRNA and the immune mechanism in AIS. This study has important guiding significance for the progress, outcome of AIS, and the development of new medicine.

Therapeutic Potential of a Combination of Electroacupuncture and Human iPSC-Derived Small Extracellular Vesicles for Ischemic Stroke

This paper aimed to explore the roles of the combination of electroacupuncture (EA) and induced pluripotent stem cell-derived small extracellular vesicles (iPSC-EVs) on mice with ischemic stroke and the underlying mechanisms. A focal cerebral ischemia model was established in C57BL/6 mice through middle cerebral artery occlusion (MCAO). After 3 days, neurological impairment and motor function were examined by performing behavioral tests. The infarct volume and neuronal apoptosis were examined using TTC staining and TUNEL assays. Flow cytometry was performed to assess the proliferation of T lymphocytes. The changes in the interleukin (IL)-33/ST2 axis were evaluated by immunofluorescence and Western blotting. The combination of EA and iPSC-EVs treatment ameliorated neurological impairments and reduced the infarct volume and neuronal apoptosis in MCAO mice. EA plus iPSC-EVs suppressed T helper (Th1) and Th17 responses and promoted the regulatory T cell (Treg) response. In addition, EA plus iPSC-EVs exerted neuroprotective effects by regulating the IL-33/ST2 axis and inhibiting the microglia and astrocyte activation. Taken together, the study shows that EA and iPSC-EVs exerted a synergistic neuroprotective effect in MCAO mice, and this treatment may represent a novel potent therapy for ischemic stroke and damage to other tissues.

The Role of Immune Cells in Post-Stroke Angiogenesis and Neuronal Remodeling: The Known and the Unknown

Following a cerebral ischemic event, substantial alterations in both cellular and molecular activities occur due to ischemia-induced cerebral pathology. Mounting evidence indicates that the robust recruitment of immune cells plays a central role in the acute stage of stroke. Infiltrating peripheral immune cells and resident microglia mediate neuronal cell death and blood-brain barrier disruption by releasing inflammation-associated molecules. Nevertheless, profound immunological effects in the context of the subacute and chronic recovery phase of stroke have received little attention. Early attempts to curtail the infiltration of immune cells were effective in mitigating brain injury in experimental stroke studies but failed to exert beneficial effects in clinical trials. Neural tissue damage repair processes include angiogenesis, neurogenesis, and synaptic remodeling, etc. Post-stroke inflammatory cells can adopt divergent phenotypes that influence the aforementioned biological processes in both endothelial and neural stem cells by either alleviating acute inflammatory responses or secreting a variety of growth factors, which are substantially involved in the process of angiogenesis and neurogenesis. To better understand the multiple roles of immune cells in neural tissue repair processes post stroke, we review what is known and unknown regarding the role of immune cells in angiogenesis, neurogenesis, and neuronal remodeling. A comprehensive understanding of these inflammatory mechanisms may help identify potential targets for the development of novel immunoregulatory therapeutic strategies that ameliorate complications and improve functional rehabilitation after stroke.

T cells in the brain inflammation

The immune system is deeply involved in autoimmune diseases of the central nervous system (CNS), such as multiple sclerosis, N-methyl-d-aspartate (NMDA) receptor encephalitis, and narcolepsy. Additionally, the immune system is involved in various brain diseases including cerebral infarction and neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). In particular, reports related to T cells are increasing. T cells may also play important roles in brain deterioration and dementia that occur with aging. Our understanding of the role of immune cells in the context of the brain has been greatly improved by the use of acute ischemic brain injury models. Additionally, similar neural damage and repair events are shown to occur in more chronic brain neurodegenerative brain diseases. In this review, we focus on the role of T cells, including CD4⁺ T cells, CD8⁺ T cells and regulatory T cells (Tregs) in cerebral infarction and neurodegenerative diseases.

Xinglou Chengqi Decoction improves neurological function in experimental stroke mice as evidenced by gut microbiota analysis and network pharmacology

The current study was designed to explore the brain protection mechanism of Xinglou Chengqi Decoction (XCD) based on gut microbiota analysis and network pharmacology. A transient middle cerebral artery occlusion (MCAO) model of mice was established, followed by behavioral evaluation, TTC and TUNEL staining. Additionally, to investigate the effects of gut microbiota on neurological function after stroke, C57BL/6 mice were treated with anti-biotic cocktails 14 days prior to ischemic stroke (IS) to deplete the gut microbiota. High-throughput 16S rDNA gene sequencing, metabonomics technique, and flow multifactor technology were used to analyze bacterial communities, SCFAs and inflammatory cytokines respectively. Finally, as a supplement, network pharmacology and molecular docking were applied to fully explore the multicomponent-multitarget-multichannel mechanism of XCD in treating IS, implicated in ADME screening, target identification, network analysis, functional annotation, and pathway enrichment analysis. We found that XCD effectively improved neurological function, relieved cerebral infarction and decreased the neuronal apoptosis. Moreover, XCD promoted the release of anti-inflammatory factor like IL-10, while down-regulating pro-inflammatory factors such as TNF-α, IL-17A, and IL-22. Furthermore, XCD significantly increased the levels of short chain fatty acids (SCFAs), especially butyric acid. The mechanism might be related to the regulation of SCFAs-producing bacteria like Verrucomicrobia and Akkermansia, and bacteria that regulate inflammation like Paraprevotella, Roseburia, Streptophyta and Enterococcu. Finally, in the network pharmacological analysis, 51 active compounds in XCD and 44 intersection targets of IS and XCD were selected. As a validation, components in XCD docked well with key targets. It was obviously that biological processes were mainly involved in the regulation of apoptotic process, inflammatory response, response to fatty acid, and regulation of establishment of endothelial barrier in GO enrichment. XCD can improve neurological function in experimental stroke mice, partly due to the regulation of gut microbiota. Besises, XCD has the characteristic of "multi-component, multi-target and multi-channel" in the treatment of IS revealed by network pharmacology and molecular docking.

Association of Proinflammatory Cytokine Levels with Stroke Severity, Infarct Size, and Muscle Strength in the Acute Phase of Stroke

OBJECTIVE

Patterns of cytokine levels and their association with stroke severity, infarct size, and muscle strength are obscure. We aimed to analyze the immune mediators linked to T helper (Th)1, Th2, Th17, and regulatory T cell patterns and their association with stroke severity, infarct size, and muscle strength.

MATERIALS AND METHODS

We included patients with acute stroke (n = 15) and healthy non-disabled individuals (n = 20) aged > 18 years. The dependent variables were stroke severity according to the National Institute of Health Stroke Scale (NIHSS), infarct size on computed tomography, handgrip strength by dynamometry, and global muscle strength according to the Medical Research Council (MRC) scale. The independent variables were the circulating cytokine levels. The cytokine levels were compared between the groups, and correlations between the clinical data were verified.

RESULTS

The stroke group had higher interleukin (IL)-6 (p < 0.0001) and IL-10 (p < 0.0001) levels, but lower tumor necrosis factor (TNF)-α (p = 0.036) levels than the control group. IL-10 and soluble tumor necrosis factor receptor (sTNF-RII) levels were correlated with each other (r = 0.533; p = 0.042) and infarct size (r = 0.653; p = 0.033 and r = 0.689; p = 0.018, respectively). MRC scores were positively and negatively correlated with handgrip strength of the affected side (r = 0.78; p = 0.001) and NIHSS scores (r = -0.87; p < 0.0001), respectively.

CONCLUSIONS

Plasma levels of some cytokines were associated with changes in the acute phase of stroke, and IL-10 and sTNF-RII levels are potential biomarkers of infarct size.

Immune Cells in the BBB Disruption After Acute Ischemic Stroke: Targets for Immune Therapy?

Blood-Brain Barrier (BBB) disruption is an important pathophysiological process of acute ischemic stroke (AIS), resulting in devastating malignant brain edema and hemorrhagic transformation. The rapid activation of immune cells plays a critical role in BBB disruption after ischemic stroke. Infiltrating blood-borne immune cells (neutrophils, monocytes, and T lymphocytes) increase BBB permeability, as they cause microvascular disorder and secrete inflammation-associated molecules. In contrast, they promote BBB repair and angiogenesis in the latter phase of ischemic stroke. The profound immunological effects of cerebral immune cells (microglia, astrocytes, and pericytes) on BBB disruption have been underestimated in ischemic stroke. Post-stroke microglia and astrocytes can adopt both an M1/A1 or M2/A2 phenotype, which influence BBB integrity differently. However, whether pericytes acquire microglia phenotype and exert immunological effects on the BBB remains controversial. Thus, better understanding the inflammatory mechanism underlying BBB disruption can lead to the identification of more promising biological targets to develop treatments that minimize the onset of life-threatening complications and to improve existing treatments in patients. However, early attempts to inhibit the infiltration of circulating immune cells into the brain by blocking adhesion molecules, that were successful in experimental stroke failed in clinical trials. Therefore, new immunoregulatory therapeutic strategies for acute ischemic stroke are desperately warranted. Herein, we highlight the role of circulating and cerebral immune cells in BBB disruption and the crosstalk between them following acute ischemic stroke. Using a robust theoretical background, we discuss potential and effective immunotherapeutic targets to regulate BBB permeability after acute ischemic stroke.

Diverse functions and mechanisms of regulatory T cell in ischemic stroke

The inflammatory and immune processes are key pathophysiological processes in the ischemic stroke, including leukocyte infiltration and destruction of the blood-brain-barrier (BBB), which further lead to increased post-ischemic inflammation. Regulatory T cells (Tregs) are a specific subset of T lymphocytes that play a pivotal role in suppressing the activation of immune system, maintaining immune homeostasis, and regulating inflammation induced by pathogens and environmental toxins. We would like to discuss the paradox function of Tregs in ischemic stroke. The accumulating data indicate that Tregs are involved in the immune regulation and self-tolerance after ischemic stroke, contributing the outcome of ischemic stroke. Tregs could resist immune response overactivation, and were supposed to be the endogenous regulatory factors to control the immune response of ischemic brain. Although, there are still some controversies and unresolved issues about the functions and mechanisms of Tregs in ischemic stroke. More and more attention has been paid to Tregs in the pathogenesis of ischemic stroke and it might be a potential therapeutic target in the future. In this review, we will summarize the recent findings on the specific functions and mechanisms of Tregs and discuss its potential therapeutic role in ischemic stroke.

Immunosuppression and Neuroinflammation in Stroke Pathobiology

Over the preceding decades, there have been substantial advances in our knowledge of the pathophysiology of stroke. One such advance has been an increased understanding of the multifarious crosstalk in which the nervous and immune systems engage in order to maintain homeostasis. By interrupting the immune-nervous nexus, it is thought that stroke induces change in both systems. Additionally, it has been found that both innate and adaptive immunosuppression play protective roles against the effects of stroke. The release of danger-/damage-associated molecular patterns (DAMPs) activates Toll-like receptors (TLRs), contributing to the harmful inflammatory effects of ischemia/reperfusion injury after stroke; the Tyro3, Axl, and MerTK (TAM)/Gas6 system, however, has been shown to suppress inflammation via downstream signaling molecules that inhibit TLR signaling. Anti-inflammatory cytokines have also been found to promote neuroprotection following stroke. Additionally, adaptive immunosuppression merits further consideration as a potential endogenous protective mechanism. In this review, we highlight recent studies regarding the effects and mechanism of immunosuppression on the pathophysiology of stroke, with the hope that a better understanding of the function of both of innate and adaptive immunity in this setting will facilitate the development of effective therapies for post-stroke inflammation.

IL-2/IL-2R Antibody Complex Enhances Treg-Induced Neuroprotection by Dampening TNF-α Inflammation in an In Vitro Stroke Model

The present in vitro study showed that IL-2/IL-2R antibody complex facilitates Treg-induced neuroprotection in the oxygen glucose deprivation/reoxygenation (OGD/R) model of stroke. First, we examined the role of IL-2/IL-2R-treated Tregs in OGD/R-exposed rat primary cortical cells (PCCs), which represent the cell type of the ischemic gray matter in the stroke brain. Here, OGD/R induced cell death, which was attenuated by Tregs and more robustly by IL-2/IL-2R-treated Tregs, but not by IL-2/IL-2R treatment alone. Second, we next assessed IL-2/IL-2R effects in OGD/R-exposed human oligodendrocyte progenitor cells (OPCs), which correspond to the white matter injury after stroke. Results revealed that a similar pattern neuroprotection as seen in the gray matter, in that OGD/R triggered cell death, which was ameliorated by Tregs and more effectively by IL-2/IL-2R-treated Tregs, but IL-2/IL-2R treatment alone was not therapeutic. Third, as we begin to understand the mechanism underlying IL-2/IL-2R engagement of Tregs, we investigated the inflammatory response in OGD/R-exposed human neural progenitor cells (NPCs), which recapitulate both ischemic gray and white matter damage in stroke. Similar to PCCs and OPCs, OGD/R produced cell death and was blocked by Tregs and more efficiently by IL-2/IL-2R-treated Tregs, whereas IL-2/IL-2R treatment alone did not alter the ischemic insult. Moreover, the inflammatory marker, TNF-α, was upregulated after OGD/R, dampened by both Tregs and more efficiently by IL-2/IL-2R-treated Tregs but more pronounced in the latter, and not affected by IL-2/IL-2R treatment alone, suggesting IL-2/IL-2R-Treg-mediated modulation of inflammatory response in stroke. Altogether, these observations support the use of IL-2/IL-2R treatment in enhancing the anti-inflammatory effects of Tregs in stroke.

TRIM28 Expression on Dendritic Cells Prevents Excessive T Cell Priming by Silencing Endogenous Retrovirus

Acquired immune reaction is initiated by dendritic cells (DCs), which present Ags to a few naive Ag-specific T cells. Deregulation of gene expression in DCs may alter the outcome of the immune response toward immunodeficiency and/or autoimmune diseases. Expression of TRIM28, a nuclear protein that mediates gene silencing through heterochromatin, decreased in DCs from old mice, suggesting alteration of gene regulation. Mice specifically lacking TRIM28 in DCs show increased DC population in the spleen and enhanced T cell priming toward inflammatory effector T cells, leading to acceleration and exacerbation in experimental autoimmune encephalomyelitis. TRIM28-deficient DCs were found to ectopically transcribe endogenous retrovirus (ERV) elements. Combined genome-wide analysis revealed a strong colocalization among the decreased repressive histone mark H3K9me3-transcribed ERV elements and the derepressed host genes that were related to inflammation in TRIM28-deficient DCs. This suggests that TRIM28 occupancy of ERV elements critically represses expression of proximal inflammatory genes on the genome. We propose that gene silencing through repressive histone modification by TRIM28 plays a role in maintaining the integrity of precise gene regulation in DCs, which prevents aberrant T cell priming to inflammatory effector T cells.

The effect of fingolimod on regulatory T cells in a mouse model of brain ischaemia

Background

The role of the immune system in stroke is well-recognised. Fingolimod, an immunomodulatory agent licensed for the management of relapsing-remitting multiple sclerosis, has been shown to provide benefit in rodent models of stroke. Its mechanism of action, however, remains unclear. We hypothesised fingolimod increases the number and/or function of regulatory T cells (Treg), a lymphocyte population which promotes stroke recovery. The primary aim of this study was to rigorously investigate the effect of fingolimod on Tregs in a mouse model of brain ischaemia. The effect of fingolimod in mice with common stroke-related comorbidities (ageing and hypercholesteremia) was also investigated.

Methods

Young (15–17 weeks), aged C57BL/6 mice (72–73 weeks), and ApoE^−/− mice fed a high-fat diet (20–21 weeks) underwent permanent electrocoagulation of the left middle cerebral artery. Mice received either saline or fingolimod (0.5 mg/kg or 1 mg/kg) at 2, 24, and 48 h post-ischaemia via intraperitoneal injection. Another cohort of young mice (8–9, 17–19 weeks) received short-term (5 days) or long-term (10 days) fingolimod (0.5 mg/kg) treatment. Flow cytometry was used to quantify Tregs in blood, spleen, and lymph nodes. Immunohistochemistry was used to quantify FoxP3+ cell infiltration into the ischaemic brain.

Results

Fingolimod significantly increased the frequency of Tregs within the CD4+ T cell population in blood and spleen post-ischaemia in all three mouse cohorts compared to untreated ischemic mice. The highest splenic Treg frequency in fingolimod-treated mice was observed in ApoE^−/− mice (9.32 ± 1.73% vs. 7.8 ± 3.01% in young, 6.09 ± 1.64% in aged mice). The highest circulating Treg frequency was also noted in ApoE^−/− mice (8.39 ± 3.26% vs. 5.43 ± 2.74% in young, 4.56 ± 1.60% in aged mice). Fingolimod significantly increased the number of FoxP3+ cells in the infarct core of all mice. The most pronounced effects were seen when mice were treated for 10 days post-ischaemia.

Conclusions

Fingolimod increases Treg frequency in spleen and blood post-ischaemia and enhances the number of FoxP3+ cells in the ischaemic brain. The effect of fingolimod on this regulatory cell population may underlie its neuroprotective activity and could be exploited as part of future stroke therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02083-5.

Regulatory T cells in ischemic stroke

The pathophysiological mechanisms of neuroinflammation, angiogenesis, and neuroplasticity are currently the hotspots of researches in ischemic stroke. Regulatory T cells (Tregs), a subset of T cells that control inflammatory and immune responses in the body, are closely related to the pathogenesis of ischemic stroke. They participate in the inflammatory response and neuroplasticity process of ischemic stroke by various mechanisms, such as secretion of anti‐inflammatory factors, inhibition of pro‐inflammatory factors, induction of cell lysis, production of the factors that promote neural regeneration, and modulation of microglial and macrophage polarization. However, it remains unclear whether Tregs play a beneficial or deleterious role in ischemic stroke and the effect of Tregs in different stages of ischemic stroke. Here, we discuss the dynamic changes of Tregs at various stages of experimental and clinical stroke, the potential mechanisms under Tregs in regulating stroke and the preclinical studies of Tregs‐related treatments, in order to provide a reference for clinical treatment.

Aging, Immunity, and COVID-19: How Age Influences the Host Immune Response to Coronavirus Infections?

The novel coronavirus severe acute respiratory syndrome coronavirus 2 causing the Coronavirus disease (COVID-19) pandemic has ravaged the world with over 72 million total cases and over 1.6 million deaths worldwide as of early December 2020. An overwhelming preponderance of cases and deaths is observed within the elderly population, and especially in those with pre-existing conditions and comorbidities. Aging causes numerous biological changes in the immune system, which are linked to age-related illnesses and susceptibility to infectious diseases. Age-related changes influence the host immune response and therefore not only weaken the ability to fight respiratory infections but also to mount effective responses to vaccines. Immunosenescence and inflamm-aging are considered key features of the aging immune system wherein accumulation of senescent immune cells contribute to its decline and simultaneously increased inflammatory phenotypes cause immune dysfunction. Age-related quantitative and qualitative changes in the immune system affect cells and soluble mediators of both the innate and adaptive immune responses within lymphoid and non-lymphoid peripheral tissues. These changes determine not only the susceptibility to infections, but also disease progression and clinical outcomes thereafter. Furthermore, the response to therapeutics and the immune response to vaccines are influenced by age-related changes within the immune system. Therefore, better understanding of the pathophysiology of aging and the immune response will not only help understand age-related diseases but also guide targeted management strategies for deadly infectious diseases like COVID-19.

Cellular and Molecular Mechanisms of R/S-Roscovitine and CDKs Related Inhibition under Both Focal and Global Cerebral Ischemia: A Focus on Neurovascular Unit and Immune Cells

Ischemic stroke is the second leading cause of death worldwide. Following ischemic stroke, Neurovascular Unit (NVU) inflammation and peripheral leucocytes infiltration are major contributors to the extension of brain lesions. For a long time restricted to neurons, the 10 past years have shown the emergence of an increasing number of studies focusing on the role of Cyclin-Dependent Kinases (CDKs) on the other cells of NVU, as well as on the leucocytes. The most widely used CDKs inhibitor, (R)-roscovitine, and its (S) isomer both decreased brain lesions in models of global and focal cerebral ischemia. We previously showed that (S)-roscovitine acted, at least, by modulating NVU response to ischemia. Interestingly, roscovitine was shown to decrease leucocytes-mediated inflammation in several inflammatory models. Specific inhibition of roscovitine majors target CDK 1, 2, 5, 7, and 9 showed that these CDKs played key roles in inflammatory processes of NVU cells and leucocytes after brain lesions, including ischemic stroke. The data summarized here support the investigation of roscovitine as a potential therapeutic agent for the treatment of ischemic stroke, and provide an overview of CDK 1, 2, 5, 7, and 9 functions in brain cells and leucocytes during cerebral ischemia.

Revealing the Pharmacological Mechanism of Acorus tatarinowii in the Treatment of Ischemic Stroke Based on Network Pharmacology

Aim

Stroke is the second significant cause for death, with ischemic stroke (IS) being the main type threatening human being's health. Acorus tatarinowii (AT) is widely used in the treatment of Alzheimer disease, epilepsy, depression, and stroke, which leads to disorders of consciousness disease. However, the systemic mechanism of AT treating IS is unexplicit. This article is supposed to explain why AT has an effect on the treatment of IS in a comprehensive and systematic way by network pharmacology.

Methods and Materials

ADME (absorbed, distributed, metabolized, and excreted) is an important property for screening-related compounds in AT, which were screening out of TCMSP, TCMID, Chemistry Database, and literature from CNKI. Then, these targets related to screened compounds were predicted via Swiss Targets, when AT-related targets database was established. The gene targets related to IS were collected from DisGeNET and GeneCards. IS-AT is a common protein interactive network established by STRING Database. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment were analysed by IS-AT common target genes. Cytoscape software was used to establish a visualized network for active compounds-core targets and core target proteins-proteins interactive network. Furthermore, we drew a signal pathway picture about its effect to reveal the basic mechanism of AT against IS systematically.

Results

There were 53 active compounds screened from AT, inferring the main therapeutic substances as follows: bisasaricin, 3-cyclohexene-1-methanol-α,α,4-trimethyl,acetate, cis,cis,cis-7,10,13-hexadecatrienal, hydroxyacoronene, nerolidol, galgravin, veraguensin, 2′-o-methyl isoliquiritigenin, gamma-asarone, and alpha-asarone. We obtained 398 related targets, 63 of which were the same as the IS-related genes from targets prediction. Except for GRM2, remaining 62 target genes have an interactive relation, respectively. The top 10 degree core target genes were IL6, TNF, IL1B, TLR4, NOS3, MAPK1, PTGS2, VEGFA, JUN, and MMP9. There were more than 20 terms of biological process, 7 terms of cellular components, and 14 terms of molecular function through GO enrichment analysis and 13 terms of signal pathway from KEGG enrichment analysis based on P < 0.05.

Conclusion

AT had a therapeutic effect for ischemic via multicomponent, multitarget, and multisignal pathway, which provided a novel research aspect for AT against IS.

Interleukin-17 and ischaemic stroke

Interleukin-17 (IL-17) is a cytokine family that includes 6 members, IL-17A through IL-17F, most of them are reported to have pro-inflammatory role. Through binding to their receptors (IL-17Rs), IL-17 activates the intracellular signalling pathways to play an important role in autoimmune diseases, including rheumatoid arthritis (RA) and multiple sclerosis (MS). Ischaemic stroke is a complex pathophysiological process mainly caused by regional cerebral ischaemia. Inflammatory factors contribute to the physiological process of stroke that leads to poor prognosis. IL-17 plays a crucial role in promoting inflammatory response and inducing secondary injury in post-stroke. Though immune cells and inflammatory factors have been reported to be involved in the damage of stroke, the functions of IL-17 in this process need to be elucidated. This review focuses on the pathological modulation and the mechanism of IL-17 family in ischaemic stroke and seeking to provide new insights for future therapies.

Altered lncRNAs Transcriptomic Profiles in Atherosclerosis-Induced Ischemic Stroke

Long non-coding RNAs (lncRNAs) can not only regulate gene transcription and translation, but also participate in the development of central nervous system diseases as epigenetic modification factors. However, their functional significance in atherosclerosis-induced ischemic stroke (AIIS) is unclear. The study aimed to screen out differentially expressed lncRNAs (delncRNAs), and to elucidate their potential regulatory mechanisms in the pathophysiology of AIIS. Based on the clinicopathological features and clinical images, we screened out 10 patients with AIIS and recruited 10 healthy volunteers. Then we used microarray to detect the whole blood RNA of subjects, and explored the biological functions of delncRNAs by GO and KEGG analysis. After further analyzing the delncRNAs of THP-1 stimulated with ox-LDL, selective lncRNAs were screened and a corresponding lncRNA-mRNA interaction network was constructed through co-expression analysis. We yielded 180 delncRNAs (44 up-regulated and 136 down-regulated) and 218 demRNAs (45 up-regulated and 173 down-regulated). Lnc-SCARNA8 and lnc-SNRPN-2 are the most significant elevated and decreased lncRNA in AIIS, respectively. The delncRNAs may play a significant role in ubiquitination-mediated protein degradation signaling pathways. According to lncRNA-mRNA network, the expression of vacuolar protein sorting 13 homolog B (VPS13B) and biliverdin reductase B (BLVRB) were significantly regulated. Our findings suggest that the ubiquitinated proteasome pathway, VPS13B and BLVRB may play a fundamental role in the pathological process of AIIS.