The Emerging Roles of Gamma-Delta T Cells in Tissue Inflammation in Experimental Autoimmune Encephalomyelitis

Understanding Multiple Sclerosis Pathophysiology and Current Disease-Modifying Therapies: A Review of Unaddressed Aspects

Multiple sclerosis (MS) is a complex autoimmune disorder of the central nervous system (CNS) with an unknown etiology and pathophysiology that is not completely understood. Although great strides have been made in developing disease-modifying therapies (DMTs) that have significantly improved the quality of life for MS patients, these treatments do not entirely prevent disease progression or relapse. Identifying the unaddressed pathophysiological aspects of MS and developing targeted therapies to fill in these gaps are essential in providing long-term relief for patients. Recent research has uncovered some aspects of MS that remain outside the scope of available DMTs, and as such, yield only limited benefits. Despite most MS pathophysiology being targeted by DMTs, many patients still experience disease progression or relapse, indicating that a more detailed understanding is necessary. Thus, this literature review seeks to explore the known aspects of MS pathophysiology, identify the gaps in present DMTs, and explain why current treatments cannot entirely arrest MS progression.

Revealing the molecular mechanisms in wound healing and the effects of different physiological factors including diabetes, age, and stress

Wounds are the common fates in various microbial infections and physical damages including accidents, surgery, and burns. In response, a healthy body with a potent immune system heals that particular site within optimal time by following the coagulation, inflammation, proliferation, and remodeling phenomenon. However, certain malfunctions in the body due to various diseases particularly diabetes and other physiological factors like age, stress, etc., prolong the process of wound healing through various mechanisms including the Akt, Polyol, and Hexosamine pathways. The current review thoroughly explains the wound types, normal wound healing mechanisms, and the immune system's role. Moreover, the mechanistic role of diabetes is also elaborated comprehensively.

IL-23 stabilizes an effector Treg cell program in the tumor microenvironment

Interleukin-23 (IL-23) is a proinflammatory cytokine mainly produced by myeloid cells that promotes tumor growth in various preclinical cancer models and correlates with adverse outcomes. However, as to how IL-23 fuels tumor growth is unclear. Here, we found tumor-associated macrophages to be the main source of IL-23 in mouse and human tumor microenvironments. Among IL-23-sensing cells, we identified a subset of tumor-infiltrating regulatory T (Treg) cells that display a highly suppressive phenotype across mouse and human tumors. The use of three preclinical models of solid cancer in combination with genetic ablation of Il23r in Treg cells revealed that they are responsible for the tumor-promoting effect of IL-23. Mechanistically, we found that IL-23 sensing represents a crucial signal driving the maintenance and stabilization of effector Treg cells involving the transcription factor Foxp3. Our data support that targeting the IL-23/IL-23R axis in cancer may represent a means of eliciting antitumor immunity.

Tissue-resident and innate-like T cells in patients with advanced chronic liver disease

Chronic liver disease results from the orchestrated interplay of components of innate and adaptive immunity in response to liver tissue damage. Recruitment, positioning, and activation of immune cells can contribute to hepatic cell death, inflammation, and fibrogenesis. With disease progression and increasing portal pressure, repeated translocation of bacterial components from the intestinal lumen through the epithelial and vascular barriers leads to persistent mucosal, hepatic, and systemic inflammation which contributes to tissue damage, immune dysfunction, and microbial infection. It is increasingly recognised that innate-like and adaptive T-cell subsets located in the liver, mucosal surfaces, and body cavities play a critical role in the progression of advanced liver disease and inflammatory complications of cirrhosis. Mucosal-associated invariant T cells, natural killer T cells, γδ T cells, and tissue-resident memory T cells in the gut, liver, and ascitic fluid share certain characteristic features, which include that they recognise microbial products, tissue alarmins, cytokines, and stress ligands in tissues, and perform effector functions in chronic liver disease. This review highlights recent advances in the comprehension of human tissue-resident and unconventional T-cell populations and discusses the mechanisms by which they contribute to inflammation, fibrosis, immunosuppression, and antimicrobial surveillance in patients with cirrhosis. Understanding the complex interactions of immune cells in different compartments and their contribution to disease progression will provide further insights for effective diagnostic interventions and novel immunomodulatory strategies in patients with advanced chronic liver disease.

A new method for the treatment of myocardial ischemia-reperfusion injury based on γδT cell-mediated immune response

Acute myocardial ischemia is a disease with high morbidity and mortality, and re-perfusion is currently the best intervention. However, re-perfusion may lead to further myocardial injury and increase the area of myocardial infarction. The mechanism of myocardial ischemia-re-perfusion injury is complex, but with more in-depth study, it has been proved that the immune system plays an important role in the process of MIRI. Among them, the γδT cell population has received increasing attention as the main early source of IL-17A in many immune response models. Because γδT cells have the characteristics of linking innate immunity and adaptive immunity,they can rapidly produce IL-17A and produce subsequent immune killing of cardiomyocytes. It can be seen that γδT cells play an important role in MIRI. Therefore, here we review the research progress of immune response in myocardial ischemia-re-perfusion injury, the key characteristics of γδT cells and the role of rapidly produced IL-17 in myocardial ischemia-re-perfusion injury, and propose relevant treatment strategies and prospects for myocardial repair, in order to provide new ideas and methods for clinical treatment of myocardial ischemia-re-perfusion injury.

Tff3-/- Knock-Out Mice with Altered Lipid Metabolism Exhibit a Lower Level of Inflammation following the Dietary Intake of Sodium Chloride for One Week

A high salt intake causes hemodynamic changes and promotes immune response through cell activation and cytokine production, leading to pro-inflammatory conditions. Transgenic Tff3^-/- knock-out mice (TFF3ko) (n = 20) and wild-type mice (WT) (n = 20) were each divided into the (1) low-salt (LS) group and (2) high-salt (HS) group. Ten-week-old animals were fed with standard rodent chow (0.4% NaCl) (LS) or food containing 4% NaCl (HS) for one week (7 days). Inflammatory parameters from the sera were measured by Luminex assay. The integrin expression and rates of T cell subsets of interest from the peripheral blood leukocytes (PBLs) and mesenteric lymph nodes (MLNs) were measured using flow cytometry. There was a significant increase in high-sensitivity C reactive protein (hsCRP) only in the WT mice following the HS diet, while there were no significant changes in the serum levels of IFN-γ, TNF-α, IL-2, IL-4, or IL-6 as a response to treatment in either study groups. The rates of CD4⁺CD25⁺ T cells from MLNs decreased, while CD3⁺γδTCR⁺ from peripheral blood increased following the HS diet only in TFF3ko. γδTCR expressing T cell rates decreased in WT following the HS diet. The CD49d/VLA-4 expression decreased in the peripheral blood leukocytes in both groups following the HS diet. CD11a/LFA-1 expression significantly increased only in the peripheral blood Ly6C^-CD11a^high monocytes in WT mice following salt loading. In conclusion, salt-loading in knock-out mice caused a lower level of inflammatory response compared with their control WT mice due to gene depletion.

Contact lens-induced corneal parainflammation involving Ly6G+ cell infiltration requires IL-17A and γδ T cells

PURPOSE

Previously, using a murine model, we reported that contact lens (CL) wear induced corneal parainflammation involving CD11c+ cells after 24 h and Ly6G+ cells (neutrophils) after 5-6 days. Here, we investigated the role of IL-17 and γδ T cells in the CL-induced neutrophil response.

METHODS

CL-wearing C57BL/6 wild-type (WT) mice were compared to lens-wearing IL-17A/F single or double gene knock-out mice, or mice treated with UC7-13D5 monoclonal antibody to functionally deplete γδ T cells. Contralateral eyes served as no lens wear controls. Corneal Ly6G+ and γδ T cell responses were quantified as was expression of genes encoding pro-inflammatory cytokines IL-17A/F, IL-β, IL-18 and expression of IL-17A/F protein.

RESULTS

After 6 days lens wear, WT corneas showed Ly6G+ cell infiltration while remaining free of visible pathology. In contrast, lens-wearing corneas of IL-17AF (-/-), IL-17A (-/-) mice and γδ T cell-depleted mice showed little or no Ly6G+ cell infiltration. No Ly6G+ cell infiltration was detected in contralateral eye controls. Lens-wearing WT corneas also showed a significant increase in γδ T cells after 24 h that was maintained after 6 days of wear, and significantly increased cytokine gene expression after 6 days versus contralateral controls: IL-18 & IL-17A (∼3.9 fold) and IL-23 (∼6.5-fold). Increased IL-17A protein (∼4-fold) was detected after 6 days lens wear. γδ T cell-depletion abrogated these lens-induced changes in cytokine gene and protein expression.

CONCLUSION

Together, these data show that IL-17A and γδ T cells are required for Ly6G+ cell (neutrophil) infiltration of the cornea during contact lens-induced parainflammation.

Modified Gegen Qinlian decoction ameliorates DSS-induced chronic colitis in mice by restoring the intestinal mucus barrier and inhibiting the activation of γδT17 cells

BACKGROUND

Current therapeutics for ulcerative colitis (UC) have limitations. Classical Formula Gegen Qinlian decoction (GQD) is derived from Shang Han Lun and has a long history of treating gastrointestinal diseases such as diarrhea and UC. Nevertheless, the exact mechanism of it needs to be further clarified.

PURPOSE

We aimed to investigate the treatment effects of modified GQD (MGQD) on dextran sodium sulfate (DSS)-induced chronic colitis in mice and conduct further exploration of its underlying mechanisms.

METHODS

The protective effect of MGQD was estimated in a DSS-induced chronic colitis mouse model. Model evaluation included body weight, disease activity index (DAI) score, colon length and histopathology. Alcian Blue/Phosphoric Acid Schiff (AB/PAS) staining, transmission electron microscopy (TEM), immunofluorescence and real time‒PCR (RT-PCR) were used to assess goblet cell function. ELISA, flow cytometry and immunofluorescence were applied to estimate the immunoinflammatory status. Western blot was performed to test the protein expression levels of relevant pathways and related receptors. All experiments were conducted in duplicate.

RESULTS

MGQD alleviated DSS‑induced chronic colitis symptoms in mice, protected goblet cell function and restored the intestinal mucus barrier. Furthermore, MGQD efficiently suppressed the abnormal immune inflammatory response and the activate of γδT17 cells and NLRP3 inflammasome.

CONCLUSION

The mechanisms by which MGQD protects against DSS-induced chronic colitis may involve restoring goblet cell function, repairing the intestinal mucus barrier, and modulating the immune inflammatory response. More importantly, MGQD inhibited NLRP3 inflammasome-associated signaling pathway activation, which consequently reduced the activation of γδT17 cells.

Ex vivo assays show human gamma-delta T cells specific for common allergens are Th1-polarized in allergic donors

Gamma-delta (γδ) T cells contribute to the pathology of many immune-related diseases; however, no ex vivo assays to study their activities are currently available. Here, we established a methodology to characterize human allergen-reactive γδ T cells in peripheral blood using an activation-induced marker assay targeting upregulated 4-1BB and CD69 expression. Broad and reproducible ex vivo allergen-reactive γδ T cell responses were detected in donors sensitized to mouse, cockroach, house dust mite, and timothy grass, but the response did not differ from that in non-allergic participants. The reactivity to 4 different allergen extracts was readily detected in 54.2%-100% of allergic subjects in a donor- and allergen-specific pattern and was abrogated by T cell receptor (TCR) blocking. Analysis of CD40L upregulation and intracellular cytokine staining revealed a T helper type 1 (Th1)-polarized response against mouse and cockroach extract stimulation. These results support the existence of allergen-reactive γδ T cells and their potential use in rebalancing dysregulated Th2 responses in allergic diseases.

The immunology of multiple sclerosis

Our incomplete understanding of the causes and pathways involved in the onset and progression of multiple sclerosis (MS) limits our ability to effectively treat this complex neurological disease. Recent studies explore the role of immune cells at different stages of MS and how they interact with cells of the central nervous system (CNS). The findings presented here begin to question the exclusivity of an antigen-specific cause and highlight how seemingly distinct immune cell types can share common functions that drive disease. Innovative techniques further expose new disease-associated immune cell populations and reinforce how environmental context is critical to their phenotype and subsequent role in disease. Importantly, the differentiation of immune cells into a pathogenic state is potentially reversible through therapeutic manipulation. As such, understanding the mechanisms that provide plasticity to causal cell types is likely key to uncoupling these disease processes and may identify novel therapeutic targets that replace the need for cell ablation.

Target tumor microenvironment by innate T cells

The immunosuppressive tumor microenvironment (TME) remains one of the most prevailing barriers obstructing the implementation of effective immunotherapy against solid-state cancers. Eminently composed of immunosuppressive tumor associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs) among others, the TME attenuates the effects of immune checkpoint blockade and adoptive cell therapies, mandating a novel therapy capable of TME remediation. In this review we explore the potential of three innate-like T cell subsets, invariant natural killer T (iNKT), mucosal-associated invariant T (MAIT) cells, and gamma delta T (γδT) cells, that display an intrinsic anti-TAM/MDSC capacity. Exhibiting both innate and adaptive properties, innate-like T cell types express a subset-specific TCR with distinct recombination, morphology, and target cell recognition, further supplemented by a variety of NK activating receptors. Both NK activating receptor and TCR activation result in effector cell cytotoxicity against targeted immunosuppressive cells for TME remediation. In addition, innate-like T cells showcase moderate levels of tumor cell killing, providing dual antitumor and anti-TAM/MDSC function. This latent antitumor capacity can be further bolstered by chimeric antigen receptor (CAR) engineering for recognition of tumor specific antigens to enhance antitumor targeting. In contrast with established CAR-T cell therapies, adoption of these innate-like cell types provides an enhanced safety profile without the risk of graft versus host disease (GvHD), due to their non-recognition of mismatched major histocompatibility complex (MHC) molecules, for use as widely accessible, allogeneic “off-the-shelf” cancer immunotherapy.

Isolation and expansion of murine γδ T cells from mouse splenocytes

Elucidation of the function of gamma delta T cells (γδ T cells) requires robust models that show how γδ T cells are commonly involved in inflammation, since very little is known about the factors that promote and control their development and function. There are few studies of murine γδ T cells primarily because these cells have proven difficult to isolate, expand and characterize. Here, we describe a simple method that utilizes key expansion elements to isolate and expand murine CD4^-CD8^-CD3⁺ γδ T cells typically found in secondary lymphoid tissues. Expansion of γδ T cells reached 150-fold by day 8 of culture, depended on exogenous IL-2, αCD3, and αCD28, and supported efficient and reproducible in vitro differentiation. These studies showed high production of cytokines IFNγ and Granzyme B, with the novel finding of IL-24 upregulation as well. Expression analysis of expanded γδ T cells, after treatment with IL-2, revealed high levels of Granzyme B, Granzyme D, and IFNγ. Lactate dehydrogenase (LDH) cytotoxicity assays showed that expanded γδ T cells were effective at inducing >90% cytolysis of murine MC38 colon cancer, E0771 breast cancer, and B16 melanoma cells at 10:1 effector to target ratios. These findings indicated that murine γδ T cells can be successfully isolated, expanded, and used to perform preclinical therapy studies.

IFNγ-Producing γ/δ T Cells Accumulate in the Fetal Brain Following Intrauterine Inflammation

Intrauterine inflammation impacts prenatal neurodevelopment and is linked to adverse neurobehavioral outcomes ranging from cerebral palsy to autism spectrum disorder. However, the mechanism by which a prenatal exposure to intrauterine inflammation contributes to life-long neurobehavioral consequences is unknown. To address this gap in knowledge, this study investigates how inflammation transverses across multiple anatomic compartments from the maternal reproductive tract to the fetal brain and what specific cell types in the fetal brain may cause long-term neuronal injury. Utilizing a well-established mouse model, we found that mid-gestation intrauterine inflammation resulted in a lasting neutrophil influx to the decidua in the absence of maternal systemic inflammation. Fetal immunologic changes were observed at 72-hours post-intrauterine inflammation, including elevated neutrophils and macrophages in the fetal liver, and increased granulocytes and activated microglia in the fetal brain. Through unbiased clustering, a population of Gr-1+ γ/δ T cells was identified as the earliest immune cell shift in the fetal brain of fetuses exposed to intrauterine inflammation and determined to be producing high levels of IFNγ when compared to γ/δ T cells in other compartments. In a case-control study of term infants, IFNγ was found to be elevated in the cord blood of term infants exposed to intrauterine inflammation compared to those without this exposure. Collectively, these data identify a novel cellular immune mechanism for fetal brain injury in the setting of intrauterine inflammation.

Optical coherence tomography monitoring and diagnosing retinal changes in multiple sclerosis

This study explores the use of optical coherence tomography (OCT) to monitor and diagnose multiple sclerosis (MS). The analysis of reduced total macular volume and peripapillary retinal nerve fiber layer thinning are shown. The severity of these defects increases as MS progresses, reflecting the progressive degeneration of nerve fibers and retinal ganglion cells. The OCT parameters are noninvasive, sensitive indicators that can be used to assess the progression of neurodegeneration and inflammation in MS.

Changes in γδT Cells in Peripheral Blood of Patients with Ulcerative Colitis Exacerbations

The role of γδT cells in ulcerative colitis (UC) is well confirmed in experimental animals and demonstrated in many clinical observations. Recent investigations have indicated that UC is associated with several forms of immune imbalance, such as an imbalance between effector T cells and regulatory T cells. However, little is known about the cellular aspect of clinical colitis exacerbations. We observed 140 patients with histologically confirmed UC over the course of 8 years. We investigated the percentage of γδT and αβT cells in peripheral blood of patients and also the expression of various surface markers (CD25, CD54, CD62L). Patients were assembled into stable colitis and exacerbated colitis groups. The percentage of γδT and αβT cells was evaluated by Ortho Cytorone Absolute flow cytometer. In patients with exacerbated colitis we observed a decrease of γδT cells in peripheral blood and an increased ratio of αβT/γδT. Additionally, we found that exacerbation results in a significant increase of percentage of γδTCD25, γδTCD54 and γδTCD62L lymphocytes in peripheral blood when compared to patients with stable colitis. Exacerbation of ulcerative colitis results in a decreased percentage of γδT cells in peripheral blood with increase of CD25, CD54 and CD62L expressing γδT cells. This may represent the effect of cell activation and migration, similar to that observed after the surgical trauma. We hope that this observation may help to predict exacerbations in colitis patients.

Increased Vδ1γδT cells predominantly contributed to IL-17 production in the development of adult human post-infectious irritable bowel syndrome

BACKGROUND

γδT cells play an important role in the mucosa inflammation and immunity-associated disorders. Our previous study reported that γδ T cells producing IL-17 were involved in the pathogenesis of post-infectious irritable bowel syndrome (PI-IBS). However, their subset characteristic profile in this kind of disease remains unclear. Thus the current study's aim is to investigate the functionally predominant subset and its role in PI-IBS.

METHODS

The total T cells were collected from the peripheral blood of patients with PI-IBS. The peripheral proportion of Vδ1 and Vδ2 subset was detected by FACS after stained with anti δ1-PE and anti δ2-APC. The local colonic proportion of this two subsets were measured under laser confocal fluorescence microscope. Vδ1 γδ T cells were enriched from the total peripheral T cells by minoantibody-immuno-microbeads (MACS) method and cultured, functionally evaluated by CCK-8 assay (proliferation), CD69/CD62L molecules expression assay (activation) and ELISA (IL-17 production) respectively.

RESULTS

1. Vδ1 γδ T cells significantly increased while Vδ2 γδ T cells remained unchanged in both the peripheral blood and local colonic tissue from PI-IBS patients (p < 0.05). 2. When cultured in vitro, the Vδ1 γδ T cells remarkably proliferated, activated and produced IL-17 (p < 0.05).

CONCLUSIONS

Our results suggest that Vδ1 γδ T cells was the predominant γδ T cells subset in both peripheral and intestinal tissue, and was the major IL-17 producing γδ T cells in PI-IBS.

Synthetic retinoid AM80 inhibits IL-17 production of gamma delta T cells and ameliorates biliary atresia in mice

BACKGROUND & AIMS

Recent evidence suggests that Interleukin (IL)-17-producing gamma delta ( γδ ) T cells are the dominant pathogenic cellular component in designated autoimmune or inflammatory diseases, including biliary atresia (BA). We have previously demonstrated that retinoids effectively suppress T-helper cell (Th) 17 differentiation.

METHODS

Here, we established an in vitro system, enabling investigations of the effect of AM80 on the IL-17 production of γδ T cells. Additionally, we tested the therapeutic effect of AM80 in the Rotavirus-induced mouse model of BA. Co-incubation of γδ T cells with IL-23 and anti-CD28 mAb proved most effective in inducing an IL-17 response in vitro. The effect of AM80 on human CCR6+CD26+ V δ 2 cells was assessed by flow cytometry.

RESULTS

AM80 efficiently reduced IL-17 production by murine γδ T cells and the expression of the master transcription factor Retinoid-Orphan-Receptor- γ t (ROR γτ ) in a dose-dependent manner. The fraction of human CCR6+CD26+ V δ 2 cells was significantly reduced by co-incubation with AM80. Moreover, AM80 also inhibited IL-17 production by liver-infiltrating γδ T cells isolated from animals suffering from BA. Intraperitoneal treatment with AM80 ameliorated BA-associated inflammation. However, AM80 treatment was not sufficient to control disease progression in the murine model, despite reduced inflammatory activity in the animals.

CONCLUSIONS

Retinoids are very efficient in down-regulating IL-17 production by γδ T cells in vitro and, to a lesser extent, in the BA mouse model. However, retinoids do not suffice for the control of disease progression. Thus, our data suggest that IL-17 is not the only factor contributing to the pathogenesis of BA.

LAY SUMMARY

Biliary atresia (BA) is a rare disease which affects infants, causing progressive liver failure in most children, and is the most common indication for paediatric liver transplantation. We have previously demonstrated that IL-17, produced by γδ T cells, contributes to hepatic inflammation in the murine model of BA and is increased in the livers of infants suffering from the disease. In the study at hand, we demonstrate that treatment with AM80, a synthetic retinoid with superior pharmacological properties, effectively inhibits the IL-17 production of gamma delta T cells without generating systemic immunosuppression. Although all-trans retinoic acid (ATRA) has been demonstrated to suppress differentiation of IL-17-producing conventional T-helper cells (Th17) in vitro, the therapeutic application of ATRA in vivo is limited by the compound's potential side effects caused by its instability and lack of receptor specificity. Our study is the first to show that AM80 suppresses the IL-17 production of γδ T cells in a very efficient manner and that hepatic inflammation is ameliorated in mice suffering from BA. However, AM80 treatment does not suffice to block the disease progression. We conclude that factors other than IL-17 drive the progressive inflammation in BA. The addition of retinoids to the treatment regime of children suffering from BA might decrease the disease burden; however, further research is needed to clarify the pathomechanism and possible therapeutic interventions in humans.

A randomized controlled trial with a delayed-type hypersensitivity model using keyhole limpet haemocyanin to evaluate adaptive immune responses in man

AIMS

Keyhole limpet haemocyanin (KLH) immunization is a clinical model for the evaluation of human antibody responses. The current study evaluated the anti-KLH antibody response after KLH immunization and the delayed-type hypersensitivity response following intradermal KLH administration, using objective imaging techniques.

METHODS

Healthy male subjects aged 24.5 ± 5.4 years were randomized to intramuscular immunization with 100 μg KLH (n = 12) or placebo (n = 3). Anti-KLH antibody (Ig) M and IgG titres were determined before and every 7 days after KLH immunization for a total of 28 days. Twenty-one days after the immunization, all subjects received 1 μg KLH intradermally. Prior to and 2 days after intradermal KLH administration, skin blood perfusion, erythema and oedema were quantified using noninvasive imaging tools. Repeated measures ANCOVAs were used to analyse data.

RESULTS

Anti-KLH IgM and IgG titres increased after KLH immunization compared to placebo (estimated difference [ED]: 37%, 95% confidence interval [CI]: 19-51% and ED: 68%, 95% CI: 56-76% respectively). Upon intradermal KLH administration an increase in skin blood perfusion (ED: 10.9 arbitrary units (AU), 95% CI: 1.4-20.4 AU) and erythema (ED: 0.3 AU, 95% CI: 0.1-0.5 AU) was observed in KLH-immunized subjects compared to placebo.

CONCLUSION

KLH immunization followed by intradermal KLH administration resulted in increased anti-KLH IgM and IgG titres and a delayed-type hypersensitivity response quantified by an increase in skin blood perfusion and erythema. Using noninvasive imaging tools the KLH model has the potential to serve as an objective tool to study the pharmacodynamics of T-cell-directed immunomodulatory drugs.

Contributions of T cells in multiple sclerosis: what do we currently know?

BACKGROUND

Multiple sclerosis (MS) is a complex autoimmune disorder characterized by neurologic dysfunction. The symptoms worsen as the disease progresses to the relapsing stage.

AIM

This study aimed to examine the role of T cells in MS pathogenesis.

MATERIALS AND METHODS

The review was performed based on articles obtained from PsycINFO, PubMed, Web of Science, and CINAHL. Search terms and phrases, such as "multiple sclerosis," "MS," "T cells," "development," "Dysregulated T cells," and "Effector T cells", were used to identify articles that could help explore the research topic.

RESULTS

The pathogenesis of MS is linked to the regulatory, inflammatory, suppressive, and effector roles of T cells. However, the actual roles of specific T cell subsets in MS development are not well understood.

DISCUSSION

The study revealed a significant link between MS and T cell activity. Targeting T cells is a potential strategy for the development of new therapies to manage MS.

CONCLUSION

MS is a complex demyelinating condition that affects several million people around the world. Research has revealed that various classes of T cells, including effector T cells and regulatory T cells, influence the development and progression of MS. Further investigations are required to elucidate the underlying mechanisms through which specific T cell populations influence MS pathogenesis.

Inhibition of the activation of γδT17 cells through PPARγ-PTEN/Akt/GSK3β/NFAT pathway contributes to the anti-colitis effect of madecassic acid

Type-17 immune response, mediated mainly by IL-17, plays a critical role in ulcerative colitis. Previously, we showed that madecassic acid (MA), the main active ingredient of Centella asiatica herbs for anti-colitis effect, ameliorated dextran sulfate sodium (DSS)-induced mouse colitis through reducing the level of IL-17. Here, we explore the effect of MA on the activation of γδT17 cells, an alternative source of IL-17 in colitis. In DSS-induced colitis mice, oral administration of MA decreased the number of γδT17 cells and attenuated the inflammation in the colon, and the anti-colitis effect of MA was significantly counteracted by redundant γδT17 cells, suggesting that the decrease in γδT17 cells is important for the anti-colitis effect of MA. In vitro, MA could inhibit the activation but not the proliferation of γδT17 cells at concentrations without evident cytotoxicity. Antibody microarray profiling showed that the inhibition of MA on the activation of γδT17 cells involved PPARγ–PTEN/Akt/GSK3β/NFAT signals. In γδT17 cells, MA could reduce the nuclear localization of NFATc1 through inhibiting Akt phosphorylation to promote GSK3β activation. Moreover, it was confirmed that MA inhibited the Akt/GSK3β/NFATc1 pathway and the activation of γδT17 cells through activating PPARγ to increase PTEN expression and phosphorylation. The correlation between activation of PPARγ, decrease in γδT17 cell number, and amelioration of colitis by MA was validated in mice with DSS-induced colitis. In summary, these findings reveal that MA inhibits the activation of γδT17 cells through PPARγ–PTEN/Akt/GSK3β/NFAT pathway, which contributes to the amelioration of colitis.

IL-22 hinders antiviral T cell responses and exacerbates ZIKV encephalitis in immunocompetent neonatal mice

BACKGROUND

The Zika virus (ZIKV) outbreak that occurred in multiple countries was linked to increased risk of nervous system injuries and congenital defects. However, host immunity- and immune-mediated pathogenesis in ZIKV infection are not well understood. Interleukin-22 (IL-22) is a crucial cytokine for regulating host immunity in infectious diseases. Whether IL-22 plays, a role in ZIKV infection is unknown.

METHODS

The cellular source of IL-22 was identified in IFNAR-/- mice and wild-type (WT) neonatal mice during ZIKV infection. To determine the role of IL-22, we challenged 1-day-old WT and IL-22-/- mice with ZIKV and monitored clinical manifestations. Glial cell activation in the brain was assessed by confocal imaging. ZIKV-specific CD8+ T cell responses in both the spleen and brain were analyzed by flow cytometry. In addition, glial cells were cultured in vitro and infected with ZIKV in the presence of IL-22, followed by the evaluation of cell proliferation, cytokine expression, and viral loads.

RESULTS

We found that γδ T cells were the main source of IL-22 during ZIKV infection in both the spleen and brain. WT mice began to exhibit weight loss, staggered steps, bilateral hind limb paralysis, and weakness at 10 days post-infection (dpi) and ultimately succumbed to infection at 16-19 dpi. IL-22 deficiency lessened weight loss, moderated the systemic inflammatory response, and greatly improved clinical signs of neurological disease and mortality. ZIKV infection also induced the activation of microglia and astrocytes in vitro. Additional analysis demonstrated that the absence of IL-22 resulted in reduced activation of microglia and astrocytes in the cortex. Although IL-22 displayed a negligible effect on glial cells in vitro, IL-22-/- mice mounted more vigorous ZIKV-specific CD8+ T cell responses, which led to a more effective control of ZIKV in the brain.

CONCLUSIONS

Our data revealed a pathogenic role of IL-22 in ZIKV encephalitis.

The Gut-CNS Axis in Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune inflammatory disease of the CNS driven by the inflammatory activity of peripheral immune cells recruited to the CNS and by CNS-resident glial cells. MS pathogenesis has been linked to both genetic and environmental factors. In addition, the commensal flora have been shown to modulate immune processes relevant to MS pathogenesis. We discuss the effects of the gut microbiota on T cells and glial cells, and their relevance for the control of inflammation and neurodegeneration in MS. A better understanding of the gut-CNS axis will shed new light on the mechanisms of disease pathogenesis, and may help to guide the development of efficacious therapies for MS.

The Role of IL-6 in Skin Fibrosis and Cutaneous Wound Healing

The timely resolution of wound healing is critical for restoring the skin as a protective barrier. The switch from a proinflammatory to a reparative microenvironment must be tightly regulated. Interleukin (IL)-6 is a key modulator of the inflammatory and reparative process: it is involved in the differentiation, activation, and proliferation of leukocytes, endothelial cells, keratinocytes, and fibroblasts. This review examines the role of IL-6 in the healing of cutaneous wounds, and how dysregulation of IL-6 signaling can lead to either fibrosis or a failure to heal. The role of an IL-6/TGF-β feedback loop is discussed in the context of fibrogenesis, while IL-6 expression and responses in advanced age, diabetes, and obesity is outlined regarding the development of chronic wounds. Current research on therapies that modulate IL-6 is explored. Here, we consider IL-6′s diverse impact on cutaneous wound healing.

Interleukin 23 and autoimmune diseases: current and possible future therapies

PURPOSE

IL-23 is a central proinflammatory cytokine with a wide range of influence over immune response. It is implicated in several autoimmune diseases due to the infinite inflammatory loops it can create through the positive feedbacks of both IL-17 and IL-22 arms. This made IL-23 a key target of autoimmune disorders therapy, which indeed was proven to inhibit inflammation and ameliorate diseases. Current autoimmune treatments targeting IL-23 are either by preventing IL-23 ligation to its receptor (IL-23R) via antibodies or inhibiting IL-23 signaling by signaling downstream mediators' inhibitors, with each approach having its own pros and cons.

METHODS

Literature review was done to further understand the biology of IL-23 and current therapies.

RESULTS

In this review, we discuss the biological features of IL-23 and its role in the pathogenesis of autoimmune diseases including psoriasis, rheumatoid arthritis and inflammatory bowel diseases. Advantages, limitations and side effects of each concept will be reviewed, suggesting several advanced IL-23-based bio-techniques to generate new and possible future therapies to overcome current treatments problems.

Transcriptomic signature of gut microbiome-contacting cells in colon of spontaneously hypertensive rats

Fecal matter transfer from hypertensive patients and animals into normotensive animals increases blood pressure, strengthening the evidence for gut-microbiota interactions in the control of blood pressure. However, cellular and molecular events involved in gut dysbiosis-associated hypertension remain poorly understood. Therefore, our objective in this study was to use gene expression profiling to characterize the gut epithelium layer in the colon in hypertension. We observed significant suppression of components of T cell receptor (TCR) signaling in the colonic epithelium of spontaneously hypertensive rats (SHR) when compared with Wistar Kyoto (WKY) normotensive rats. Western blot analysis confirmed lower expression of key proteins including T cell surface glycoprotein CD3 gamma chain (Cd3g) and lymphocyte cytosolic protein 2 (Lcp2). Furthermore, lower expression of cytokines and receptors responsible for lymphocyte proliferation, differentiation, and activation (e.g., Il12r, Il15ra, Il7, Il16, Tgfb1) was observed in the colonic epithelium of the SHR. Finally, Alpi and its product, intestinal alkaline phosphatase, primarily localized in the epithelial cells, were profoundly lower in the SHR. These observations demonstrate that the colonic epithelium undergoes functional changes linked to altered immune, barrier function, and dysbiosis in hypertension.

Activated γδ T Cells Promote Dendritic Cell Maturation and Exacerbate the Development of Experimental Autoimmune Uveitis (EAU) in Mice

Our previous study reveals that gamma delta (γδ) T cells were activated and dendritic cells (DCs) underwent maturation during the inflammation phase in experimental autoimmune uveitis (EAU) mice, and the interaction between DCs and γδ T cells may significantly exacerbate the development of EAU. However, the interactions between DCs and γδ T cells that can affect DCs maturation to influence EAU development must be further addressed. In this study we showed that mature DC numbers in TCR-δ^-/- (KO) EAU mice were lower than those in wild-type (WT) C57BL/6 (B6) mice. The γδ T cells harvested from WT EAU mice secreted more interferon-γ (IFN-γ), however, after blocking IFN-γ, the maturation of DCs was significantly downregulated. By contrast, the percentage of IFN-γ- and IL-17-producing CD4⁺ T cells in KO EAU mice decreased to a greater extent than that in WT EAU mice during the inflammatory phase. Additionally, the levels of IFN-γ/IL-17 in serum were in agreement with those of CD4⁺ T cells. Furthermore, after activated γδ T cells injection, the inflammatory symptoms of EAU mice were more aggravated. In vitro co-cultures of both cell types showed that activated γδ T cells may induce DCs to generate higher levels of intracellular cell adhesion molecule-1 (ICAM-1/CD54), CD80, CD83, and CD86. Moreover, co-culture of the two cells may induce the activation of CD4⁺ T cells. Taken together, our results demonstrated that activated γδ T cells may promote DCs maturation and further enhance the generation of Th1/Th17 cells in EAU mice, resulting in exacerbated EAU.

Microglial NLRP3 inflammasome activation in multiple sclerosis

Multiple sclerosis (MS) is a chronic, autoimmune and neuroinflammatory disease of the central nervous system (CNS) mediated by autoreactive T cells directed against myelin antigens. Although the crucial role of adaptive immunity is well established in MS, the contribution of innate immunity has only recently been appreciated. Microglia are the main innate immune cells of the CNS. Similar to other myeloid cells, microglia recognize both exogenous and host-derived endogenous danger signals through pattern recognition receptors (PRRs) localized on their cell surface such as Toll Like receptor 4, or in the cytosol such as NLRP3. The second one is the sensor protein of the multi-molecular NLRP3 inflammasome complex in activated microglia that promotes the maturation and secretion of proinflammatory cytokines, interleukin-1β and interleukin-18. Overactivation of microglia and aberrant activation of the NLRP3 inflammasome have been implicated in the pathogenesis of MS. Indeed, experimental data, together with post-mortem and clinical studies have revealed an increased expression of NLRP3 inflammasome complex elements in microglia and other immune cells. In this review, we focus on microglial NLRP3 inflammasome activation in MS. First, we overview the basic knowledge about MS, microglia and the NLRP3 inflammasome. Then, we summarize studies about microglial NLRP3 inflammasome activation in MS and its animal models. We also highlight experimental therapeutic approaches that target different steps of NLRP inflammasome activation. Finally, we discuss future research avenues and new methods in this rapidly evolving area.

γδ T cells in rheumatic diseases: from fundamental mechanisms to autoimmunity

The innate and adaptive arms of the immune system tightly regulate immune responses in order to maintain homeostasis and host defense. The interaction between those two systems is critical in the activation and suppression of immune responses which if unchecked may lead to chronic inflammation and autoimmunity. γδ T cells are non-conventional lymphocytes, which express T cell receptor (TCR) γδ chains on their surface and straddle between innate and adaptive immunity. Recent advances in of γδ T cell biology have allowed us to expand our understanding of γδ T cell in the dysregulation of immune responses and the development of autoimmune diseases. In this review, we summarize current knowledge on γδ T cells and their roles in skin and joint inflammation as commonly observed in rheumatic diseases.

Innate, innate-like and adaptive lymphocytes in the pathogenesis of MS and EAE

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) in which the immune system damages the protective insulation surrounding the nerve fibers that project from neurons. A hallmark of MS and its animal model, experimental autoimmune encephalomyelitis (EAE), is autoimmunity against proteins of the myelin sheath. Most studies in this field have focused on the roles of CD4+ T lymphocytes, which form part of the adaptive immune system as both mediators and regulators in disease pathogenesis. Consequently, the treatments for MS often target the inflammatory CD4+ T-cell responses. However, many other lymphocyte subsets contribute to the pathophysiology of MS and EAE, and these subsets include CD8+ T cells and B cells of the adaptive immune system, lymphocytes of the innate immune system such as natural killer cells, and subsets of innate-like T and B lymphocytes such as γδ T cells, natural killer T cells, and mucosal-associated invariant T cells. Several of these lymphocyte subsets can act as mediators of CNS inflammation, whereas others exhibit immunoregulatory functions in disease. Importantly, the efficacy of some MS treatments might be mediated in part by effects on lymphocytes other than CD4+ T cells. Here we review the contributions of distinct subsets of lymphocytes on the pathogenesis of MS and EAE, with an emphasis on lymphocytes other than CD4+ T cells. A better understanding of the distinct lymphocyte subsets that contribute to the pathophysiology of MS and its experimental models will inform the development of novel therapeutic approaches.

Keratinocyte-specific deletion of the IL-6RΑ exacerbates the inflammatory response during irritant contact dermatitis

Irritant Contact Dermatitis (ICD) is the most common occupational skin disorder. During ICD, keratinocytes initiate the inflammatory cascade by producing cytokines including IL-6. This laboratory previously reported that IL-6 deficiency exacerbates skin inflammation during ICD, yet the role of the IL-6Rα in keratinocyte function has yet to be elucidated. To investigate how IL-6Rα function in keratinocytes influences the inflammatory response during ICD, keratinocyte-specific IL-6Rα KO (IL6ra^Δker) and WT mice were exposed to two well-known occupational irritants; JP-8 jet fuel, and benzalkonium chloride (BKC), or acetone control for three days. Dermatitis lesions were collected and flow cytometric and immunohistochemical analyses revealed that IL6ra^Δker skin displayed increased populations of CD11b⁺CD45⁺ and F4/80⁺ cells respectively relative to WT. However, IL6ra^Δker mouse skin contained reduced numbers of γδ T cells relative to WT. Furthermore, IL6ra^Δker skin expressed increased levels of pro-inflammatory cytokines including IL-1β, IL-22, and CCL4 but decreased levels of anti-inflammatory cytokines IL-4 and IL-10. These results indicate that epidermal keratinocyte IL-6Rα function modulates epidermal hyperplasia, immune cell infiltration into skin and cytokine expression during ICD and suggests that the previously reported protective effect of IL-6 during ICD might be mediated primarily by keratinocyte derived IL-6Rα.

The Pivotal Role of Regulatory T Cells in the Regulation of Innate Immune Cells

The distinction between innate and adaptive immunity is one of the basic tenets of immunology. The co-operation between these two arms of the immune system is a major determinant of the resistance or susceptibility of the host following pathogen invasion. Hence, this interactive co-operation between cells of the innate and adaptive immunity is of significant interest to immunologists. The sub-population of CD4⁺ T cells with regulatory phenotype (regulatory T cells; Tregs), which constitute a part of the adaptive immune system, have been widely implicated in the regulation of the immune system and maintenance of immune homeostasis. In the last two decades, there has been an explosion in research describing the role of Tregs and their relevance in several immunopathologies ranging from inflammation to cancer. The majority of these studies focus on the role of Tregs on the cells of the adaptive immune system. Recently, there is significant interest in the role of Tregs on cells of the innate immune system. In this review, we examine the literature on the role of Tregs in immunology. Specifically, we focus on the emerging knowledge of Treg interaction with dendritic cells, macrophages, neutrophils, and γδ T cells. We highlight this interaction as an important link between innate and adaptive immune systems which also indicate the far-reaching role of Tregs in the regulation of immune responses and maintenance of self-tolerance and immune homeostasis.

Unexpected alliance between syndecan-1 and innate-like T cells to protect host from autoimmune effects of interleukin-17

Innate-like T cells, namely natural killer T (NKT) and γδ T cells, play critical roles in linking innate and adaptive immune responses through rapid production of cytokines. Prominent among these cytokines is interleukin-17 (IL-17), which is a potent proinflammatory cytokine that plays a critical role in host defense against fungi and extracellular bacteria. However, excessive IL-17-production promotes autoimmune diseases, including psoriasis, multiple sclerosis, rheumatoid arthritis, inflammatory bowel disease, and systemic lupus erythematosus. IL-17 has also been implicated in regulating body fat, which is highly relevant given rises in obesity and type 2 diabetes. NKT cells, γδ T cells and mucosal-associated invariant T cells (MAIT) are the major sources of IL-17 involved in protection of mucosal surfaces from opportunistic infections and causing autoimmunity when become dysregulated. Given the pathogenic effects of IL-17, efforts have been directed towards understanding mechanisms that guard against IL-17 overproduction. One novel potent mechanism is mediated by the heparan sulfate proteoglycan, syndecan-1 (sdc1), which is selectively expressed by IL-17-producing subsets of NKT and γδ T cells. This unexpected role for sdc1 is uncovered by analysis of NKT and γδ T cells in sdc1-deficient mice. In this mini-review, we discuss selective expression of sdc1 by these innate T cells and consequences of its absence on IL-17 homeostasis and pathological implications.

Retinoic Acid, Leaky Gut, and Autoimmune Diseases

A leaky gut has been observed in a number of autoimmune diseases including type 1 diabetes, multiple sclerosis, inflammatory bowel disease, and systemic lupus erythematosus. Previous studies from our laboratory have shown that lupus mice also bear a leaky gut and that the intestinal barrier function can be enhanced by gut colonization of probiotics such as Lactobacillus spp. Retinoic acid (RA) can increase the relative abundance of Lactobacillus spp. in the gut. Interestingly, RA has also been shown to strengthen the barrier function of epithelial cells in vitro and in the absence of probiotic bacteria. These reports bring up an interesting question of whether RA exerts protective effects on the intestinal barrier directly or through regulating the microbiota colonization. In this review, we will discuss the roles of RA in immunomodulation, recent literature on the involvement of a leaky gut in different autoimmune diseases, and how RA shapes the outcomes of these diseases.

Syndecan-1 Regulates Psoriasiform Dermatitis by Controlling Homeostasis of IL-17-Producing γδ T Cells

IL-17 is a potent proinflammatory cytokine that drives pathogenesis of multiple autoimmune diseases, including psoriasis. A major source of pathogenic IL-17 is a subset of γδ T cells (Tγδ17) that acquires the ability to produce IL-17 while developing in the thymus. The mechanisms that regulate homeostasis of Tγδ17 cells and their roles in psoriasis, however, are not fully understood. In this paper, we show that the heparan sulfate proteoglycan syndecan-1 (sdc1) plays a critical role in regulating homeostasis of Tγδ17 cells and modulating psoriasis-like skin inflammation in mice. sdc1 was predominantly expressed by Tγδ17 cells (but not IL-17^- Tγδ cells) in the thymus, lymph nodes, and dermis. sdc1 deficiency significantly and selectively increased the frequency and absolute numbers of Tγδ17 cells by mechanisms that included increased proliferation and decreased apoptosis. Adoptive transfer experiments ruled out a significant role of sdc1 expressed on nonhematopoietic cells in halting expansion and proliferation of sdc1-deficient Tγδ17 cells. When subjected to imiquimod-induced psoriasiform dermatitis, Tγδ17 cells in sdc1KO mice displayed heightened responses accompanied by significantly increased skin inflammation than their wild-type counterparts. Furthermore, transferred sdc1-deficient γδ T cells caused more severe psoriasiform dermatitis than their sdc1-sufficient counterparts in TCR-βδ KO hosts. The results uncover a novel role for sdc1 in controlling homeostasis of Tγδ17 cells and moderating host responses to psoriasis-like inflammation.

Integration of T-cell receptor, Notch and cytokine signals programs mouse γδ T-cell effector differentiation

γδ T‐cells perform a wide range of tissue‐ and disease‐specific functions that are dependent on the effector cytokines produced by these cells. However, the aggregate signals required for the development of interferon‐γ (IFNγ) and interleukin‐17 (IL‐17) producing γδ T‐cells remain unknown. Here, we define the cues involved in the functional programming of γδ T‐cells, by examining the roles of T‐cell receptor (TCR), Notch, and cytokine‐receptor signaling. KN6 γδTCR‐transduced Rag2^−/− T‐cell progenitors were cultured on stromal cells variably expressing TCR and Notch ligands, supplemented with different cytokines. We found that distinct combinations of these signals are required to program IFNγ versus IL‐17 producing γδ T‐cell subsets, with Notch and weak TCR ligands optimally enabling development of γδ17 cells in the presence of IL‐1β, IL‐21 and IL‐23. Notably, these cytokines were also shown to be required for the intrathymic development of γδ17 cells. Together, this work provides a framework of how signals downstream of TCR, Notch and cytokine receptors integrate to program the effector function of IFNγ and IL‐17 producing γδ T‐cell subsets.

Heat shock protein 70 protects mouse against post-infection irritable bowel syndrome via up-regulating intestinal γδ T cell's Th17 response

Background

This study investigated the role of HSP70 in modulating intestinal γδ T cells’ Th17 response in Trichinella spiralis-induced PI-IBS mice model.

Methods

The intestinal HSP70’s expression and mRNA level were measured by Western blot and RT-PCR. The intestinal γδ T cell’s morphological changes were analyzed using immunofluorescence staining and confocal laser scanning microscope. The pro-inflammatory cytokines’ level was detected by ELISA. The isolated and purified γδ T cells were pre-incubated with HSP70 and their functions including proliferation, apoptosis, activation and production of IL-17 were also detected.

Results

Heat treatment augmented intestinal HSP70 expression and alleviated the clinical presentations in PI-IBS mice. Meanwhile, intestinal γδ T cells and local IL-17 level were increased by pre-induction of HSP70. HSP70 promoted the proliferation of PI-IBS mice’s intestinal γδ T cells, inhibited the apoptosis and stimulated these cells to secret IL-17 rather than IFN-γ.

Conclusion

Our results suggest that HSP70 plays a protective role via up-regulating intestinal γδ T cell’s Th17 response in PI-IBS mice.

GPR54 deficiency reduces the Treg population and aggravates experimental autoimmune encephalomyelitis in mice

GPR54 is highly expressed in the central nervous system and plays a crucial role in pubertal development. However, GRP54 is also expressed in the immune system, implying possible immunoregulatory functions. Here we investigated the role of GPR54 in T cell and immune tolerance. GPR54 deficiency led to an enlarged thymus, an increased number of thymocytes, and altered thymic micro-architecture starting around puberty, indicating GPR54 function in T-cell development through its regulatory effect on the gonadal system. However, flow cytometry revealed a significant reduction in the peripheral regulatory T cell population and a moderate decrease in CD4 single-positive thymocytes in prepubertal Gpr54^-/- mice. These phenotypes were confirmed in chimeric mice with GPR54 deficient bone marrow-derived cells. In addition, we found elevated T cell activation in peripheral and thymic T cells in Gpr54^-/- mice. When intact mice were immunized with myelin oligodendrocyte glycoprotein, a more severe experimental autoimmune encephalomyelitis (EAE) developed in the Gpr54^-/- mice. Interestingly, aggravated EAE disease was also manifested in castrated and bone marrow chimeric Gpr54^-/- mice compared to the respective wild-type control, suggesting a defect in self-tolerance resulting from GPR54 deletion through a mechanism that bypassed sex hormones. These findings demonstrate a novel role for GPR54 in regulating self-tolerant immunity in a sex hormone independent manner.

The influence and impact of ageing and immunosenescence (ISC) on adaptive immunity during multiple sclerosis (MS) and the animal counterpart experimental autoimmune encephalomyelitis (EAE)

The human ageing process encompasses mechanisms that effect a decline in homeostasis with increased susceptibility to disease and the development of chronic life-threatening illness. Increasing age affects the immune system which undergoes a progressive loss of efficiency, termed immunosenescence (ISC), to impact on quantitative and functional aspects of innate and adaptive immunity. The human demyelinating disease multiple sclerosis (MS) and the corresponding animal model experimental autoimmune encephalomyelitis (EAE) are strongly governed by immunological events that primarily involve the adaptive arm of the immune response. MS and EAE are frequently characterised by a chronic pathology and a protracted disease course which thereby creates the potential for exposure to the inherent, on-going effects and consequences of ISC. Collective evidence is presented to confirm the occurrence of established and unendorsed biological markers of ISC during the development of both diseases. Moreover, results are discussed from studies during the course of MS and EAE that reveal a premature upregulation of ISC-related biomarkers which indicates untimely alterations to the adaptive immune system. The effects of ISC and a prematurely aged immune system on autoimmune-associated neurodegenerative conditions such as MS and EAE are largely unknown but current evaluation of data justifies and encourages further investigation.

γδ T cells provide the early source of IFN-γ to aggravate lesions in spinal cord injury

Immune responses and neuroinflammation are critically involved in spinal cord injury (SCI). γδ T cells, a small subset of T cells, regulate the inflammation process in many diseases, yet their function in SCI is still poorly understood. In this paper, we demonstrate that mice deficient in γδ T cells (TCRδ^-/- ) showed improved functional recovery after SCI. γδ T cells are detected at the lesion sites within 24 hours after injury and are predominantly of the Vγ4 subtype and express the inflammatory cytokine IFN-γ. Inactivating IFN-γ signaling in macrophages results in a significantly reduced production of proinflammatory cytokines in the cerebrospinal fluid (CSF) of mice with SCIs and improves functional recovery. Furthermore, treatment of SCI with anti-Vγ4 antibodies has a beneficial effect, similar to that obtained with anti-TNF-α. In SCI patients, γδ T cells are detected in the CSF, and most of them are IFN-γ positive. In conclusion, manipulation of γδ T cell functions may be a potential approach for future SCI treatment.

New Insights into the Role of IL-1β in Experimental Autoimmune Encephalomyelitis and Multiple Sclerosis

Multiple sclerosis (MS), and its animal model experimental autoimmune encephalomyelitis, are neuroinflammatory diseases driven by autoreactive pathogenic T_H cells that elicit demyelination and axonal damage. How T_H cells acquire pathogenicity and communicate with myeloid cells and cells of the CNS remain unclear. IL-1β is recognized to play an important role in experimental autoimmune encephalomyelitis (EAE) and perhaps MS. Clinical EAE is significantly attenuated in IL-1R-deficient and IL-1β-deficient mice, and IL-1β is found in the blood, cerebrospinal fluid, and CNS lesions of MS patients. In this article, we focus on new reports that elucidate the cellular sources of IL-1β and its actions during EAE, in both lymphoid tissues and within the CNS. Several immune cell types serve as critical producers of IL-1β during EAE, with this cytokine inducing response in both hematopoietic and nonhematopoietic cells. These findings from the EAE model should inspire efforts toward investigating the therapeutic potential of IL-1 blockade in MS.

Immune-checkpoint protein VISTA critically regulates the IL-23/IL-17 inflammatory axis

V-domain Immunoglobulin Suppressor of T cell Activation (VISTA) is an inhibitory immune-checkpoint molecule that suppresses CD4⁺ and CD8⁺ T cell activation when expressed on antigen-presenting cells. Vsir ^-/- mice developed loss of peripheral tolerance and multi-organ chronic inflammatory phenotypes. Vsir ^-/- CD4⁺ and CD8⁺ T cells were hyper-responsive towards self- and foreign antigens. Whether or not VISTA regulates innate immunity is unknown. Using a murine model of psoriasis induced by TLR7 agonist imiquimod (IMQ), we show that VISTA deficiency exacerbated psoriasiform inflammation. Enhanced TLR7 signaling in Vsir ^-/- dendritic cells (DCs) led to the hyper-activation of Erk1/2 and Jnk1/2, and augmented the production of IL-23. IL-23, in turn, promoted the expression of IL-17A in both TCRγδ⁺ T cells and CD4⁺ Th17 cells. Furthermore, VISTA regulates the peripheral homeostasis of CD27^- γδ T cells and their activation upon TCR-mediated or cytokine-mediated stimulation. IL-17A-producing CD27^- γδ T cells were expanded in the Vsir ^-/- mice and amplified the inflammatory cascade. In conclusion, this study has demonstrated that VISTA critically regulates the inflammatory responses mediated by DCs and IL-17-producing TCRγδ⁺ and CD4⁺ Th17 T cells following TLR7 stimulation. Our finding provides a rationale for therapeutically enhancing VISTA-mediated pathways to benefit the treatment of autoimmune and inflammatory disorders.

T lymphocyte immunophenotypes in the cerebrospinal fluid of dogs with visceral leishmaniasis

Visceral leishmaniasis (VL) is a disease causing several clinical manifestations in dogs, including neurological disorders. Nevertheless, there are few studies related to the evaluation of the brain alterations during VL. Evidences of the involvement of cerebral barriers in infected dogs was reported, including the presence of brain inflammatory infiltrate, with a predominance of CD3+ T cells. Therefore, the aim of this study was to determine the immunophenotypes of T lymphocytes in the cerebrospinal fluid (CSF), as well as in peripheral blood, and to correlate with brain alterations in dogs with VL. We detected elevated percentages of double negative (DN) and double positive (DP) T cells in the CSF, with a predominance of TCRαb. In the histopathological analysis, we observed a predominance of lymphoplasmacytic infiltrate, mainly in leptomeninges, ranging from mild to intense, and we observed a positive correlation between the intensity of inflammation in the subependymal area and the DN T cells of the CSF. Thus, the DN T cells seem be acting as villains of the immune system through pro-inflammatory mechanisms. Further, the proportion of the different population of CSF T cells did not differ from those observed in the blood, which provides us with more evidence of blood-CSF barrier breakdown. Together, the results provide more explanation to the inflammation observed in the brain of dogs with VL, which the DN T cells contribute to the origin and progression of the neurological disease. This study provides insight into the immunophenotypes of T lymphocytes in the CSF during canine visceral leishmaniasis.