Regulatory T-cell as orchestra leader in immunosuppression process of multiple sclerosis

Therapeutic role of interferon-γ in experimental autoimmune encephalomyelitis is mediated through a tolerogenic subset of splenic CD11b+ myeloid cells

Cumulative evidence has established that Interferon (IFN)-γ has both pathogenic and protective roles in Multiple Sclerosis and the animal model, Experimental Autoimmune Encephalomyelitis (EAE). However, the underlying mechanisms to the beneficial effects of IFN-γ are not well understood. In this study, we found that IFN-γ exerts therapeutic effects on chronic, relapsing-remitting, and chronic progressive EAE models. The frequency of regulatory T (Treg) cells in spinal cords from chronic EAE mice treated with IFN-γ was significantly increased with no effect on Th1 and Th17 cells. Consistently, depletion of FOXP3-expressing cells blocked the protective effects of IFN-γ, indicating that the therapeutic effect of IFN-γ depends on the presence of Treg cells. However, IFN-γ did not trigger direct in vitro differentiation of Treg cells. In vivo administration of blocking antibodies against either interleukin (IL)-10, transforming growth factor (TGF)-β or program death (PD)-1, revealed that the protective effects of IFN-γ in EAE were also dependent on TGF-β and PD-1, but not on IL-10, suggesting that IFN-γ might have an indirect role on Treg cells acting through antigen-presenting cells. Indeed, IFN-γ treatment increased the frequency of a subset of splenic CD11b+ myeloid cells expressing TGF-β-Latency Associated Peptide (LAP) and program death ligand 1 (PD-L1) in a signal transducer and activator of transcription (STAT)-1-dependent manner. Furthermore, splenic CD11b+ cells from EAE mice preconditioned in vitro with IFN-γ and myelin oligodendrocyte glycoprotein (MOG) peptide exhibited a tolerogenic phenotype with the capability to induce conversion of naïve CD4+ T cells mediated by secretion of TGF-β. Remarkably, adoptive transfer of splenic CD11b+ cells from IFN-γ-treated EAE mice into untreated recipient mice ameliorated clinical symptoms of EAE and limited central nervous system infiltration of mononuclear cells and effector helper T cells. These results reveal a novel cellular and molecular mechanism whereby IFN-γ promotes beneficial effects in EAE by endowing splenic CD11b+ myeloid cells with tolerogenic and therapeutic activities.

Targeting the CTLA-4/B7 axes in glioblastoma: preclinical evidence and clinical interventions

INTRODUCTION

Glioblastoma Multiforme (GBM) is one of the fatal cancers of the Central Nervous System (CNS). A variety of reasons exist for why previous immunotherapy strategies, especially Immune Checkpoint Blockers (ICBs), did not work in treating GBM patients. The cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) is a key immune checkpoint receptor. Its overexpression in cancer and immune cells causes tumor cell progression. CTLA-4 suppresses anti-tumor responses inside the GBM tumor-immune microenvironment.

AREAS COVERED

It has been attempted to explain the immunobiology of CTLA-4 as well as its interaction with different immune cells and cancer cells that lead to GBM progression. Additionally, CTLA-4 targeting studies have been reviewed and CTLA-4 combination therapy, as a promising therapeutic target and strategy for GBM immunotherapy, is recommended.

EXPERT OPINION

CTLA-4 could be a possible supplement for future cancer immunotherapies of GBM. However, many challenges remain such as the high toxicity of CTLA-4 blockers, and the unresponsiveness of most patients to immunotherapy. For the future clinical success of CTLA-4 blocker therapy, combination approaches with other targeted treatments would be a potentially effective strategy. Going forward, predictive biomarkers can be used to reduce trial timelines and increase the chance of success.

Dual Blockade of PD-1 and LAG3 Immune Checkpoints Increases Dendritic Cell Vaccine Mediated T Cell Responses in Breast Cancer Model

PURPOSE

Increasing the efficiency of unsuccessful immunotherapy methods is one of the most important research fields. Therefore, the use of combination therapy is considered as one of the ways to increase the effectiveness of the dendritic cell (DC) vaccine. In this study, the inhibition of immune checkpoint receptors such as LAG3 and PD-1 on T cells was investigated to increase the efficiency of T cells in response to the DC vaccine.

METHODS

We used trimethyl chitosan-dextran sulfate-lactate (TMC-DS-L) nanoparticles (NPs) loaded with siRNA molecules to quench the PD-1 and LAG3 checkpoints' expression.

RESULTS

Appropriate physicochemical characteristics of the generated NPs led to efficient inhibition of LAG3 and PD-1 on T cells, which was associated with increased survival and activity of T cells, ex vivo. Also, treating mice with established breast tumors (4T1) using NPs loaded with siRNA molecules in combination with DC vaccine pulsed with tumor lysate significantly inhibited tumor growth and increased survival in mice. These ameliorative effects were associated with increased anti-tumor T cell responses and downregulation of immunosuppressive cells in the tumor microenvironment and spleen.

CONCLUSION

These findings strongly suggest that TMC-DS-L NPs loaded with siRNA could act as a novel tool in inhibiting the expression of immune checkpoints in the tumor microenvironment. Also, combination therapy based on inhibition of PD-1 and LAG3 in combination with DC vaccine is an effective method in treating cancer that needs to be further studied.

Combination Cancer Immunotherapy with Dendritic Cell Vaccine and Nanoparticles Loaded with Interleukin-15 and Anti-beta-catenin siRNA Significantly Inhibits Cancer Growth and Induces Anti-Tumor Immune Response

PURPOSE

The invention and application of new immunotherapeutic methods can compensate for the inefficiency of conventional cancer treatment approaches, partly due to the inhibitory microenvironment of the tumor. In this study, we tried to inhibit the growth of cancer cells and induce anti-tumor immune responses by silencing the expression of the β-catenin in the tumor microenvironment and transmitting interleukin (IL)-15 cytokine to provide optimal conditions for the dendritic cell (DC) vaccine.

METHODS

For this purpose, we used folic acid (FA)-conjugated SPION-carboxymethyl dextran (CMD) chitosan (C) nanoparticles (NPs) to deliver anti-β-catenin siRNA and IL-15 to cancer cells.

RESULTS

The results showed that the codelivery of β-catenin siRNA and IL-15 significantly reduced the growth of cancer cells and increased the immune response. The treatment also considerably stimulated the performance of the DC vaccine in triggering anti-tumor immunity, which inhibited tumor development and increased survival in mice in two different cancer models.

CONCLUSIONS

These findings suggest that the use of new nanocarriers such as SPION-C-CMD-FA could be an effective way to use as a novel combination therapy consisting of β-catenin siRNA, IL-15, and DC vaccine to treat cancer.

The role of regulatory T cells in the pathogenesis and treatment of prostate cancer

Despite developments in the treatment of various cancers, prostate cancer is one of the deadliest diseases known to men. Systemic therapies such as androgen deprivation, chemotherapy, and radiation therapy have not been very successful in treating this disease. Numerous studies have shown that there is a direct relationship between cancer progression and inhibition of anti-tumor immune responses that can lead to progression of various malignancies, including prostate cancer. Interestingly, CD4⁺CD25⁺FoxP3⁺ regulatory T cells significantly accumulate and increase in draining lymph nodes and PBMCs of patients with prostate cancer and other solid tumors. In vivo and in vitro studies have shown that Tregs can suppress anti-tumor responses, which is directly related to the increased risk of cancer recurrence. Tregs are essential for preserving self-tolerance and inhibiting extra immune responses harmful to the host. Since the tumor-related antigens are mainly self-antigens, Tregs could play a major role in tumor progression. Accordingly, it has discovered that prostate cancer patients with higher Tregs have poor prognosis and low survival rates. However, anti-tumor responses can be reinforced by suppression of Tregs with using monoclonal antibodies against CD25 and CTLA-4. Therefore, depleting Tregs or suppressing their functions could be one of the effective ways for prostate cancer immunotherapy. The purpose of this review is to investigate the role of Treg cells in the progression of prostate cancer and to evaluate effective strategies for the treatment of prostate cancer by regulating Treg cells.

The Immune Landscape and Prognostic Immune Key Genes Potentially Involved in Modulating Synaptic Functions in Prostate Cancer

Background: Increasing evidence has indicated an association between differentially expressed genes (DEGs) in tumor-infiltrating immune cells (TIICs) and clinical outcome. The aim of this research is to investigate the influence of tumor microenvironment on the gene expression profile of TIICs and to identify their potential markers for modulating immune cell function in prostate cancer.

Methods: In our research, CIBERSORT algorithm was utilized to calculate the proportion of the TIICs in 164 tumor and 18 control samples from The Cancer Genome Atlas cohort. The differential expression analysis was conducted using R, and then the functional and the pathway enrichments of the DEGs were analyzed using Database for Annotation, Visualization, and Integrated Discovery, followed by integrated regulatory network analysis.

Results: As a result, nTreg, B cells, Th1, and DC cells were significantly increased, accompanied by largely decreased NK and NKT cells. The expressed immune-related gene correlation analysis showed that the signature gene expression extent of CD8 T cells was positively associated with CD4 memory activated T cells but negatively correlated with that of CD4 memory resting T cells. In addition, a total of 128 differentially expressed genes were identified. CytoHubba analysis obtained six hub genes, of which three prognostic-associated potential key molecules including CAV1, FLNA, and VCL were mainly involved in biological processes associated with the regulation of organic substance and synaptic connections.

Conclusions: This study provides a comprehensive understanding of the landscape of TIICs and the roles of the hub genes which may be valuable markers in prostate cancer diagnosis and immunotherapy.

Promising Nanotechnology Approaches in Treatment of Autoimmune Diseases of Central Nervous System

Multiple sclerosis (MS) is a chronic, autoimmune, neurodegenerative disease of the central nervous system (CNS) that yields to neuronal axon damage, demyelization, and paralysis. Although several drugs were designed for the treatment of MS, with some of them being approved in the last few decades, the complete remission and the treatment of progressive forms still remain a matter of debate and a medical challenge. Nanotechnology provides a variety of promising therapeutic tools that can be applied for the treatment of MS, overcoming the barriers and the limitations of the already existing immunosuppressive and biological therapies. In the present review, we explore literature case studies on the development of drug delivery nanosystems for the targeted delivery of MS drugs in the pathological tissues of the CNS, providing high bioavailability and enhanced therapeutic efficiency, as well as nanosystems for the delivery of agents to facilitate efficient remyelination. Moreover, we present examples of tolerance-inducing nanocarriers, being used as promising vaccines for antigen-specific immunotherapy of MS. We emphasize on liposomes, as well as lipid- and polymer-based nanoparticles. Finally, we highlight the future perspectives given by the nanotechnology field toward the improvement of the current treatment of MS and its animal model, experimental autoimmune encephalomyelitis (EAE).

Mesenchymal stem cells in experimental autoimmune encephalomyelitis model of multiple sclerosis: A systematic review and meta-analysis

BACKGROUND/AIMS

Mesenchymal stem cells (MSCs) transplantation has been considered a possible therapeutic method for Multiple Sclerosis (MS). However, no quantitative data synthesis of MSCs therapy for MS exists. We conducted a systematic review and meta-analysis to evaluate the effects of MSCs in experimental autoimmune encephalomyelitis (EAE) animal model of MS.

METHODS

We identified eligible studies published from January 1980 to January 2017 by searching four electronic databases (PubMed, MEDLINE, Embase and Web of Science). The outcome was the effects of MSCs on clinical performance evaluated by the EAE clinical score.

RESULTS

36 preclinical studies including 675 animals in MSCs treatment group, and 693 animals in control group were included in this meta-analysis. We found that MSCs transplantation significantly ameliorated the symptoms and delayed the disease progression (SMD = -1.25, 95% CI: -1.45 to -1.05, P < 0.001). However, no significant differences in effect sizes were unveiled relative to clinical score standard (P = 0.35), type of MSCs (P = 0.35), source of MSCs (P = 0.06), MSCs dose (P = 0.44), delivery methods (P = 0.31) and follow up period (P = 0.73).

CONCLUSIONS

The current study showed that MSCs transplantation could ameliorate clinical performance in EAE animal model of MS. These findings support the further studies translate MSCs to treat MS in humans.

Event-Driven Immunoprofiling Predicts Return of Disease Activity in Alemtuzumab-Treated Multiple Sclerosis

Background: Alemtuzumab is a highly effective drug for the treatment of multiple sclerosis (MS), characterized by specific patterns of depletion and repopulation. As an induction-like treatment concept, two mandatory infusion courses can inhibit long-term disease activity in the majority of patients, and additional courses can successfully manage subsequent re-emergence of disease activity. Currently, there are no biomarkers to identify patients with re-emergent disease activity requiring retreatment.

Methods: In this study, we systematically characterized 16 MS patients commencing alemtuzumab. Clinical parameters, MRI and detailed immunoprofiling were conducted every 3 months for up to 84 months.

Results: Alemtuzumab led to significant decrease in clinical disease activity in all evaluated patients. Nine out of 16 patients presented with no evidence of disease activity (NEDA)-3 up to 84 months (“complete-responder”), while 7 patients demonstrated clinical or/and subclinical MRI disease activity and received alemutzumab retreatment (“partial-responder”). In both response categories, all T- and B-cell subsets were markedly depleted after alemtuzumab therapy. In particular, absolute numbers of Th1 and Th17 cells were markedly decreased and remained stable below baseline levels—this effect was particularly pronounced in complete-responders. While mean cell numbers did not differ significantly between groups, analysis of event-driven immunoprofiling demonstrated that absolute numbers of Th1 and Th17 cells showed a reproducible increase starting 6 months before relapse activity. This change appears to predict emergent disease activity when compared with stable disease.

Conclusion: Studies with larger patient populations are needed to confirm that frequent immunoprofiling may assist in evaluating clinical decision-making of alemtuzumab retreatment.

Regulatory T cells in breast cancer as a potent anti-cancer therapeutic target

Despite marked advances in treatment approaches, breast cancer is still going to be more prevalent, worldwide. High levels of regulatory T (Treg) cells have repeatedly been demonstrated in circulation, lymph nodes, and tumor samples from patients with various cancer types. The transcription factor Forkhead box protein 3 (Foxp3)-expressing Treg cells have the high suppressive potential of the immune system and are fundamental in preserving immune homeostasis and self-tolerance. However, they enhance tumor development by curbing efficient anti-tumor immune mechanisms in malignancies. Moreover, the accumulation of Treg cells in breast tumors is related to the short overall survival of patients. Treg cell frequency has been applied as an independent predicting factor to diagnose patients with a high risk of relapse. Pulling out all populations of Treg cells to promote the efficacy of anticancer treatment methods may potentially lead to hazardous autoimmune disorders. Thus, realizing the exact structure of tumor-infiltrating Treg cells is pivotal to efficiently target Treg cells in tumors. There are exclusive and non-exclusive approaches to lower down and degrade the number/function of Treg cells. These approaches can include inhibiting tumoral migration, depletion, interference with function, and utilizing T cell plasticity. This review article attempts to clarify the implications concerning the involvement of Treg cells in breast cancer progression and discuss the current approaches in the treatment of this cancer via modulation of Treg cells function.

Implications of immunotherapy with high-dose glatiramer acetate in acute phase of spinal cord injury in rats

Objective: Recently, many researches with different viewpoints have focused on application of immunotherapy agents in treatment of spinal cord injury (SCI) according to neuroprotective results in some neurodegenerative disease. Glatiramer acetate (GA) is the most commonly used drug for Multiple sclerosis (MS) patients that exerts an immunomodulatory effect against Myelin basic protein (MBP) antigen. Materials and methods: High-dose (2mg/kg) treatment of GA for 28 consecutive days after SCI was compared with its low-dose (0.5 mg/kg) treatment, SCI control and Sham control rat groups. Results: High-dose GA group had significantly worsened outcome in standard functional recovery evaluation test (BBB) 12 weeks after SCI compared to SCI control and low-dose GA groups, which was confirmed by augmented spinal cavity volume and reduced ventral horn motor neurons in high-dose GA group; however, there was no significant difference between low-dose GA and control SCI group. In addition, proliferation test performed on lymphocytes from spleen and lymph nodes one week after SCI showed that high-dose GA injection has more significant effect on Division Index (DI) in response to MBP stimulation compared to low-dose GA and control SCI groups, which was associated with significant increase in IFN-γ, IL-4, and IL-17A secretion. Conclusion: Along with confirmation of deleterious aspects of autoimmunity resulting from autoreactive lymphocytes against myelin antigens in SCI, this study has shown that high-dose immunotherapy using GA, especially in acute phase after SCI, overwhelms any neuroprotective effect of adoptive immune system.

Systemic administration of orexin A ameliorates established experimental autoimmune encephalomyelitis by diminishing neuroinflammation

BACKGROUND

Orexins (hypocretins, Hcrt) A and B are GPCR-binding hypothalamic neuropeptides known to regulate sleep/wake states and feeding behavior. A few studies have shown that orexin A exhibits anti-inflammatory and neuroprotective properties, suggesting that it might provide therapeutic effects in inflammatory and neurodegenerative diseases like multiple sclerosis (MS). In MS, encephalitogenic Th1 and Th17 cells trigger an inflammatory response in the CNS destroying the myelin sheath. Here, we investigated the effects of peripheral orexin A administration to mice undergoing experimental autoimmune encephalomyelitis (EAE), a widely used model of MS.

METHODS

Mice were subcutaneously immunized with myelin oligodendrocyte glycoprotein peptide (MOG)_35-55 in CFA. Mice were treated intraperitoneally for five consecutive days with either PBS or 300 μg of orexin A starting at a moderate EAE score. Molecular, cellular, and histological analysis were performed by real-time PCR, ELISA, flow cytometry, and immunofluorescence.

RESULTS

Orexin A strongly ameliorated ongoing EAE, limiting the infiltration of pathogenic CD4⁺ T lymphocytes, and diminishing chemokine (MCP-1/CCL2 and IP-10/CXCL10) and cytokine (IFN-γ (Th1), IL-17 (Th17), TNF-α, IL-10, and TGF-β) expressions in the CNS. Moreover, orexin A treatment was neuroprotective, decreasing demyelination, astrogliosis, and microglial activation. Despite its strong local therapeutic effects, orexin A did not impair peripheral draining lymph node cell proliferation and Th1/Th17 cytokine production in response to MOG_35-55 in vitro.

CONCLUSIONS

Peripherally-administered orexin A ameliorated EAE by reducing CNS neuroinflammation. These results suggest that orexins may represent new therapeutic candidates that should be further investigated for MS treatment.

Selective depletion of CD11c+ CD11b+ dendritic cells partially abrogates tolerogenic effects of intravenous MOG in murine EAE

Intravenous (i.v.) injection of a soluble myelin antigen can induce tolerance, which effectively ameliorates experimental autoimmune encephalomyelitis (EAE). We have previously shown that i.v. myelin oligodendrocyte glycoprotein (MOG) induces tolerance in EAE and expands a subpopulation of tolerogenic CD11c⁺ CD11b⁺ dendritic cells (DCs) with an immature phenotype having low expression of IA and co-stimulatory molecules CD40, CD86, and CD80. Here, we further investigate the role of tolerogenic DCs in i.v. tolerance by injecting clodronate-loaded liposomes, which selectively deplete CD11c⁺ CD11b⁺ and immature DCs, but not CD11c⁺ CD8⁺ DCs and mature DCs. I.v. MOG-induced suppression of EAE was partially, yet significantly, blocked by CD11c⁺ CD11b⁺ DC depletion. While i.v. MOG inhibited IA, CD40, CD80, CD86 expression and induced TGF-β, IL-27, IL-10 production in CD11c⁺ CD11b⁺ DCs, these effects were abrogated after injection of clodronate-loaded liposomes. Depletion of CD11c⁺ CD11b⁺ DCs also precluded i.v. autoantigen-induced T-cell tolerance, such as decreased production of IL-2, IFN-γ, IL-17 and numbers of IL-2⁺ , IFN-γ⁺ , and IL-17⁺ CD4⁺ T cells, as well as an increased proportion of CD4⁺ CD25⁺ Foxp3⁺ regulatory T cells and CD4⁺ IL-10⁺ Foxp3^- Tr1 cells. CD11c⁺ CD11b⁺ DCs, through low expression of IA and costimulatory molecules as well as high expression of TGF-β, IL-27, and IL-10, play an important role in i.v. tolerance-induced EAE suppression.

pVAXhsp65 Vaccination Primes for High IL-10 Production and Decreases Experimental Encephalomyelitis Severity

Experimental autoimmune encephalomyelitis (EAE) is a demyelinating pathology of the central nervous system (CNS) used as a model to study multiple sclerosis immunopathology. EAE has also been extensively employed to evaluate potentially therapeutic schemes. Considering the presence of an immune response directed to heat shock proteins (hsps) in autoimmune diseases and the immunoregulatory potential of these molecules, we evaluated the effect of a previous immunization with a genetic vaccine containing the mycobacterial hsp65 gene on EAE development. C57BL/6 mice were immunized with 4 pVAXhsp65 doses and 14 days later were submitted to EAE induction by immunization with myelin oligodendrocyte glycoprotein (MOG_35–55) emulsified in Complete Freund's Adjuvant. Vaccinated mice presented significant lower clinical scores and lost less body weight. MOG_35–55 immunization also determined less inflammation in lumbar spinal cord but did not change CD4+CD25+Foxp3+ T cells frequency in spleen and CNS. Infiltrating cells from the CNS stimulated with rhsp65 produced significantly higher levels of IL-10. These results suggest that the ability of pVAXhsp65 vaccination to control EAE development is associated with IL-10 induction.

Multiple sclerosis: Therapeutic applications of advancing drug delivery systems

Multiple sclerosis (MS) is an inflammatory autoimmune disease of the central nervous system, which is accompanying with demyelination, neurodegeneration and sensibility to oxidative stress. In MS, auto-reactive lymphocytes cross the blood-brain barrier (BBB) and reside in the perivenous demyelinating lesions which create various distinct inflammatory demyelinated plaques situated predominantly in the white matter. The current MS-related therapeutic approaches can be classified into disease-modifying therapies (DMTs) and symptomatic therapy. DMTs suppress circulating immune cells, inhibit passing the BBB and decrease the inflammatory responses. Recent advances have remarkably delayed disease development and improved the quality of life for numerous patients. In spite of major improvements in therapeutic options, there are some limitations regarding the routes of administration and the necessity for repeated and long-term dosing in which cause to systemic disadvantageous consequences and patient non-compliance. Nanotechnology presents promising approaches to improve autoimmune disease treatment with the capability to overcome many of the limitations common to the current immunosuppressive and biological therapies. Here we emphasis on nanomedicine-based drug delivery approaches of biological immunomodulatory mediators for the treatment of multiple sclerosis. This comprehensive review details the most successful drugs in MS therapy and also focuses on conceptions and clinical potential of novel nanomedicine attitudes for inducing immunosuppression and immunological tolerance in MS to modulate abnormal and pathologic immune responses.

The role of adenosine and adenosine receptors in the immunopathogenesis of multiple sclerosis

INTRODUCTION

Multiple sclerosis (MS) is a heterogeneous neurological disorder with multifactorial etiologies characterized by demyelination, axonal degeneration, and oligodendroglial death. It is believed that both genetics and environmental risk factors such as infection are involved in disease etiology. Accumulating evidence indicates that alteration in purinergic system signaling is involved in immunity and inflammation. Adenosine, a key purine nucleoside, has been shown to be produced during metabolic stress, including ischemia, inflammatory condition, and tissue injury.

METHODS

Extracellular adenosine directly affects various physiological and pathological processes of MS by stimulating G protein-coupled adenosine receptors A1, A2A, A2B, and A3 on the surface of immune cells. It has been suggested that promotion of adenosinergic system may be an important factor in MS pathophysiology and considered as promising therapeutic target for this disease.

CONCLUSION

In this review, we will discuss about the immunopathologic effects of adenosine on MS and its animal model, experimental autoimmune encephalomyelitis.

The skewed balance between Tregs and Th17 in chronic lymphocytic leukemia

While Tregs maintain self-tolerance and inhibit antitumor responses, T helper (Th)17 cells may enhance inflammatory and antitumor responses. The balance between these two important T-cell subsets has been skewed in many immunopathologic conditions such as autoimmune and cancer diseases. B-cell chronic lymphocytic leukemia (CLL) is the most common form of leukemia in the western world and is characterized with monoclonal expansion of B lymphocytes. There is evidence which implies that the progression of CLL is associated with expansion of Treg and downregulation of Th17 cells. In this review, we will discuss about immunobiology of Treg and Th17 cells and their role in immunopathogenesis of CLL as well as their reciprocal changes during disease progression.

IL-21 and IL-21 receptor in the immunopathogenesis of multiple sclerosis

Cytokines are considered important factors in the modulation of various immune responses. Among them, interleukin (IL)-21 is one of the major immune modulators, adjusting various immune responses by affecting various immune cells. It has been suggested that IL-21 may enhance autoimmunity through different mechanisms, such as development and activation of helper T (TH)-17 and follicular helper T (TFH) cells, activation of natural killer (NK) cells, enhancing B-cell differentiation and antibody secretion and suppression of regulatory T (Treg) cells. Moreover, IL-21 has also been suggested to be an inducer of autoimmunity when following treatment of MS patients with some therapeutics such as alemtuzumab. This review will seek to clarify the precise role of IL-21/IL-21R in the pathogenesis of MS and, in its animal model, experimental autoimmune encephalomyelitis (EAE).

Multiple Sclerosis and T Lymphocytes: An Entangled Story

Multiple sclerosis (MS) is the prototypic inflammatory disease of the central nervous system (CNS) characterized by multifocal areas of demyelination, axonal damage, activation of glial cells, and immune cell infiltration. Despite intensive years of research, the etiology of this neurological disorder remains elusive. Nevertheless, the abundance of immune cells such as T lymphocytes and their products in CNS lesions of MS patients supports the notion that MS is an immune-mediated disorder. An important body of evidence gathered from MS animal models such as experimental autoimmune encephalomyelitis (EAE), points to the central contribution of CD4 T lymphocytes in disease pathogenesis. Both Th1 (producing interferon-γ) and Th17 (producing interleukin 17) CD4 T lymphocytes targeting CNS self-antigens have been implicated in MS and EAE pathobiology. Moreover, several publications suggest that CD8 T lymphocytes also participate in the development of MS lesions. The migration of activated T lymphocytes from the periphery into the CNS has been identified as a crucial step in the formation of MS lesions. Several factors promote such T cell extravasation including: molecules (e.g., cell adhesion molecules) implicated in the T cell-blood brain barrier interaction, and chemokines produced by neural cells. Finally, once in the CNS, T lymphocytes need to be reactivated by local antigen presenting cells prior to enter the parenchyma where they can initiate damage. Further investigations will be necessary to elucidate the impact of environmental factors (e.g., gut microbiota) and CNS intrinsic properties (e.g., microglial activation) on this inflammatory neurological disease.

Immunomodulatory characteristics of mesenchymal stem cells and their role in the treatment of multiple sclerosis

Multiple Sclerosis (MS) is a chronic inflammatory neurodegenerative disease of central nervous system (CNS). Although the main cause of MS is not clear, studies suggest that MS is an autoimmune disease which attacks myelin sheath of neurons. There are different therapeutic regimens for MS patients including interferon (IFN)-β, glatiramer acetate (GA), and natalizumab. However, such therapies are not quite effective and are associated with some side effects. So which, there is no complete therapeutic method for MS patients. Regarding the potent immunomodulatory effects of mesenchymal stem cells (MSCs) and their ameliorative effects in experimental autoimmune encephalopathy (EAE), it seems that MSCs may be a new therapeutic method in MS therapy. MSC transplantation is an approach to regulate the immune system in the region of CNS lesions. In this review, we have tried to discuss about the immunomodulatory properties of MSCs and their therapeutic mechanisms in MS patients.

A Trichosanthin-derived peptide suppresses type 1 immune responses by TLR2-dependent activation of CD8(+)CD28(-) Tregs

A group of 15-aa-long Trichosanthin-derived peptides was synthesized and screened based on their differential abilities to induce low-responsiveness in mouse strains with high and low susceptibility. One of them was conjugated to form a homo-tetramer Tk-tPN. At concentrations of 0.1-50 μg/ml, Tk-tPN activated CD8(+)CD28(-) Tregs in vitro to induce immune suppression as effectively as the native Trichosanthin but did not exhibit cytotoxicity. In EAE mice which were pre-treated with Tk-tPN or Tk-tPN-activated CD8(+) T cells, a marked attenuation of clinical scores was recorded together with an expansion of the CD8(+)CD28(-) Treg from 2.2% to 36.1% in vivo. A pull-down assay and signal transduction analyses indicated that the ability of Tk-tPN to convert the CD8(+)CD28(-) Treg-related cytokine secretion pattern from type 1 to type 2 depends on the TLR2-initiated signaling in macrophages. The high production of IL-4/IL-10 by the Tk-tPN-activated CD8(+)CD28(-) Treg suggests the value of using Tk-tPN as a therapeutic reagent for Th1-dominant immunological diseases.

Mycophenolate mofetil improves neurological function and alters blood T-lymphocyte subsets in rats with experimental autoimmune encephalomyelitis

Objective

This study evaluated the clinical and pathological effects of the immunosuppressive agent mycophenolate mofetil (MMF) in rats with experimental autoimmune encephalomyelitis (EAE; a model of multiple sclerosis [MS]).

Methods

EAE rats were randomly divided into 4 groups: model alone ( n = 7); low- or high-dose MMF (20 and 30 mg/kg per day, respectively, n = 6 each) orally for 14 days; methylprednisolone (20 mg/kg per day, n = 6) injected once daily for 3 days. Six normal Wistar rats served as controls. Clinical signs and histopathological findings were evaluated 14 days after treatment started.

Results

Oral administration of high-dose MMF significantly ameliorated the course of EAE in rats: cumulative clinical scores were lower and weight loss was less than in rats receiving methylprednisolone. The ameliorated disease course was associated with alleviation of histopathological signs of EAE. Treatment increased the blood proportion of CD8+, CD4+CD25+ and CD4+CD45RA+ T cells, with a concomitant reduced proportion of CD4+ T cells and ratio of CD4+ to CD8+ T cells, compared with EAE model alone rats.

Conclusions

MMF may have pharmacological potential in MS treatment and these findings may help in understanding the pathophysiological mechanism of MS.

BCG and BCG/DNAhsp65 vaccinations promote protective effects without deleterious consequences for experimental autoimmune encephalomyelitis

A prime-boost strategy conserving BCG is considered the most promising vaccine to control tuberculosis. A boost with a DNA vaccine containing the mycobacterial gene of a heat shock protein (pVAXhsp65) after BCG priming protected mice against experimental tuberculosis. However, anti-hsp65 immunity could worsen an autoimmune disease due to molecular mimicry. In this investigation, we evaluated the effect of a previous BCG or BCG/pVAXhsp65 immunization on experimental autoimmune encephalomyelitis (EAE) development. Female Lewis rats were immunized with BCG or BCG followed by pVAXhsp65 boosters. The animals underwent EAE induction and were daily evaluated for weight loss and clinical score. They were euthanized during recovery phase to assess immune response and inflammatory infiltration at the central nervous system. Previous immunization did not aggravate or accelerate clinical score or weight loss. In addition, this procedure clearly decreased inflammation in the brain. BCG immunization modulated the host immune response by triggering a significant reduction in IL-10 and IFN-γ levels induced by myelin basic protein. These data indicated that vaccination protocols with BCG or BCG followed by boosters with pVAXhsp65 did not trigger a deleterious effect on EAE evolution.

Age dependent course of EAE in Aire-/- mice

This study explores the consequences of deficiency in the autoimmune regulator (Aire) on the susceptibility to experimental autoimmune encephalomyelitis (EAE). Increased susceptibility to EAE was found in Aire knockout (KO) compared to wild type (WT) in 6month old mice. In contrast, 2month old Aire KO mice were less susceptible to EAE than WT mice, and this age-related resistance correlated with elevated proportions of T regulatory (Treg) cells in their spleen and brain. Combined with our previous findings in experimental autoimmune myasthenia gravis, we suggest an age-related association between Aire and Treg cells in the susceptibility to autoimmunity.

Regulatory T cell in stroke: a new paradigm for immune regulation

Stroke is a common, debilitating trauma that has an incompletely elucidated pathophysiology and lacks an effective therapy. FoxP3⁺CD25⁺CD4⁺ regulatory T cells (Tregs) suppress a variety of normal physiological and pathological immune responses via several pathways, such as inhibitory cytokine secretion, direct cytolysis induction, and antigen-presenting cell functional modulation. FoxP3⁺CD25⁺CD4⁺ Tregs are involved in a variety of central nervous system diseases and injuries, including axonal injury, neurodegenerative diseases, and stroke. Specifically, FoxP3⁺CD25⁺CD4⁺ Tregs exert neuroprotective effects in acute experimental stroke models. These beneficial effects, however, are difficult to elucidate. In this review, we summarized evidence of FoxP3⁺CD25⁺CD4⁺ Tregs as potentially important immunomodulators in stroke pathogenesis and highlight further investigations for possible immunotherapeutic strategies by modulating the quantity and/or functional effects of FoxP3⁺CD25⁺CD4⁺ Tregs in stroke patients.

Persistent inflammation in the CNS during chronic EAE despite local absence of IL-17 production

Experimental autoimmune encephalomyelitis (EAE) is an artificially induced demyelination of the central nervous system (CNS) that resembles multiple sclerosis in its clinical, histopathological, and immunological features. Activated Th1 and Th17 cells are thought to be the main immunological players during EAE development. This study was designed to evaluate peripheral and local contribution of IL-17 to acute and chronic EAE stages. C57BL/6 mice were immunized with MOG plus complete Freund's adjuvant followed by pertussis toxin. Mice presented an initial acute phase characterized by accentuated weight loss and high clinical score, followed by a partial recovery when the animals reached normal body weight and smaller clinical scores. Spleen cells stimulated with MOG produced significantly higher levels of IFN-γ during the acute period whereas similar IL-17 levels were produced during both disease stages. CNS-infiltrating cells stimulated with MOG produced similar amounts of IFN-γ but, IL-17 was produced only at the acute phase of EAE. The percentage of Foxp3+ Treg cells, at the spleen and CNS, was elevated during both phases. The degree of inflammation was similar at both disease stages. Partial clinical recovery observed during chronic EAE was associated with no IL-17 production and presence of Foxp3+ Treg cells in the CNS.

Targeting the shift from M1 to M2 macrophages in experimental autoimmune encephalomyelitis mice treated with fasudil

We observed the therapeutic effect of Fasudil and explored its mechanisms in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). Fasudil, a selective Rho kinase (ROCK) inhibitor, was injected intraperitoneally at 40 mg/kg/d in early and late stages of EAE induction. Fasudil ameliorated the clinical severity of EAE at different stages, and decreased the expression of ROCK-II in spleen, accompanied by an improvement in demyelination and inhibition of inflammatory cells. Fasudil mainly inhibited CD4⁺IL-17⁺ T cells in early treatment, but also elevated CD4⁺IL-10⁺ regulatory T cells and IL-10 production in late treatment. The treatment of Fasudil shifted inflammatory M1 to anti-inflammatory M2 macrophages in both early and late treatment, being shown by inhibiting CD16/32, iNOS, IL-12, TLR4 and CD40 and increasing CD206, Arg-1, IL-10 and CD14 in spleen. By using Western blot and immunohistochemistry, iNOS and Arg-1, as two most specific markers for M1 and M2, was inhibited or induced in splenic macrophages and spinal cords of EAE mice treated with Fasudil. In vitro experiments also indicate that Fasudil shifts M1 to M2 phenotype, which does not require the participation or auxiliary of other cells. The polarization of M2 macrophages was associated with the decrease of inflammatory cytokine IL-1β, TNF-α and MCP-1. These results demonstrate that Fasudil has therapeutic potential in EAE possibly through inducing the polarization of M2 macrophages and inhibiting inflammatory responses.

The role of different subsets of regulatory T cells in immunopathogenesis of rheumatoid arthritis

Rheumatoid arthritis (RA) is a common autoimmune disease and a systemic inflammatory disease which is characterized by chronic joint inflammation and variable degrees of bone and cartilage erosion and hyperplasia of synovial tissues. Considering the role of autoreactive T cells (particularly Th1 and Th17 cells) in pathophysiology of RA, it might be assumed that the regulatory T cells (Tregs) will be able to control the initiation and progression of disease. The frequency, function, and properties of various subsets of Tregs including natural Tregs (nTregs), IL-10-producing type 1 Tregs (Tr1 cells), TGF-β-producing Th3 cells, CD8⁺ Tregs, and NKT regulatory cells have been investigated in various studies associated with RA and collagen-induced arthritis (CIA) as experimental model of this disease. In this paper, we intend to submit the comprehensive information about the immunobiology of various subsets of Tregs and their roles and function in immunopathophysiology of RA and its animal model, CIA.

Laquinimod modulates B cells and their regulatory effects on T cells in multiple sclerosis

Laquinimod is an orally administered drug under development for the treatment of Multiple Sclerosis (MS), lacking a fully elucidated mode of action. We assessed the immunomodulatory effects of laquinimod in vitro on human B cells from healthy or MS patients, cultured alone or with CD4(+) T cells. Laquinimod modulated B cell markers, mainly by increasing the regulatory ones CD25, IL10 and CD86, and decreased IL4, while increasing IL10 and TGFβ in both B and T cells, in a B cell-mediated manner. These findings shed additional light on the mechanisms underlying the effects of laquinimod in MS and potentially other immune-mediated diseases.

The challenges of UV-induced immunomodulation for children's health

Exposure to solar ultraviolet radiation (UVR) is recognised to have both beneficial and harmful effects on human health. With regard to immune responses, it can lead to suppression of immunity and to the synthesis of vitamin D, a hormone that can alter both innate and adaptive immunity. The consequences in children of such UV-induced changes are considerable: first there are positive outcomes including protection against some photoallergic (for example polymorphic light eruption) and T cell-mediated autoimmune diseases (for example multiple sclerosis) and asthma, and secondly there are negative outcomes including an increased risk of skin cancer (squamous cell carcinoma, basal cell carcinoma and cutaneous malignant melanoma) and less effective control of several infectious diseases. Many uncertainties remain regarding the amount of sun exposure that would provide children with the most effective responses against the variety of immunological challenges that they are likely to experience.