IFN-γ deficiency exacerbates experimental autoimmune neuritis in mice despite a mitigated systemic Th1 immune response

Structural properties of glucan from Russula griseocarnosa and its immunomodulatory activities mediated via T cell differentiation

The polysaccharide, RGP2, was isolated from Russula griseocarnosa and its immunostimulatory effects were confirmed in cyclophosphamide (CTX)-induced immunosuppressed mice. Following purification via chromatography, structural analysis revealed that RGP2 had a molecular weight of 11.82 kDa and consisted of glucose (Glc), galactose (Gal), mannose, glucuronic acid and glucosamine. Bond structure analysis and nuclear magnetic resonance characterization confirmed that the main chain of RGP2 was formed by →6)-β-D-Glcp-(1→, →3)-β-D-Glcp-(1→ and →6)-α-D-Galp-(1→, which was substituted at O-3 of →6)-β-D-Glcp-(1→ by β-D-Glcp-(1→. RGP2 was found to ameliorate pathological damage in the spleen and enhance immune cell activity in immunosuppressed mice. Based on combined multiomics analysis, RGP2 altered the abundance of immune-related microbiota (such as Lactobacillus, Faecalibacterium, and Bacteroides) in the gut and metabolites (uridine, leucine, and tryptophan) in the serum. Compared with immunosuppressed mice, RGP2 also restored the function of antigen-presenting cells, promoted the polarization of macrophages into the M1 phenotype, positively affected the differentiation of helper T cells, and inhibited regulatory T cell differentiation through the protein kinase B (AKT)/mechanistic target of rapamycin (mTOR) pathway, ultimately exerting an immune boosting function. Overall, our findings highlight therapeutic strategies to alleviate CTX-induced immunosuppression in a clinical setting.

Biological analysis of the potential pathogenic mechanisms of Infectious COVID-19 and Guillain-Barré syndrome

Background

Guillain-Barré syndrome (GBS) is a medical condition characterized by the immune system of the body attacking the peripheral nerves, including those in the spinal nerve roots, peripheral nerves, and cranial nerves. It can cause limb weakness, abnormal sensations, and facial nerve paralysis. Some studies have reported clinical cases associated with the severe coronavirus disease 2019 (COVID-19) and GBS, but how COVID-19 affects GBS is unclear.

Methods

We utilized bioinformatics techniques to explore the potential genetic connection between COVID-19 and GBS. Differential expression of genes (DEGs) related to COVID-19 and GBS was collected from the Gene Expression Omnibus (GEO) database. By taking the intersection, we obtained shared DEGs for COVID-19 and GBS. Subsequently, we utilized bioinformatics analysis tools to analyze common DEGs, conducting functional enrichment analysis and constructing Protein-protein interaction networks (PPI), Transcription factors (TF) -gene networks, and TF-miRNA networks. Finally, we validated our findings by constructing the Receiver Operating Characteristic (ROC) curves.

Results

This study utilizes bioinformatics tools for the first time to investigate the close genetic relationship between COVID-19 and GBS. CAMP, LTF, DEFA1B, SAMD9, GBP1, DDX60, DEFA4, and OAS3 are identified as the most significant interacting genes between COVID-19 and GBS. In addition, the signaling pathway of NOD-like receptors is believed to be essential in the link between COVID-19 and GBS.

The therapeutic effects of ginkgolides in Guillain-Barré syndrome and experimental autoimmune neuritis

BACKGROUND

Guillain-Barré syndrome (GBS) is an acquired immune-mediated inflammatory peripheral neuropathy. The immune regulation of ginkgolides have been revealed in recent years. We herein investigate the potential therapeutic effects of ginkgolides both on GBS and its animal model, experimental autoimmune neuritis (EAN).

METHODS

EAN in C57BL/6 mice induced by subcutaneous injection with peripheral nerve myelin P0 protein peptide 180-199 (P0 peptide) were treated with ginkgolides at three different doses. GBS patients were randomly divided into two groups, the experimental group and the control group. The experimental group were treated with ginkgolides as soon as diagnosed.

RESULTS

Our data indicated that ginkgolides administration daily ameliorated the score of EAN and delayed the peak of disease in EAN mice. Ginkgolides also down-regulated the proportions of T helper (Th) 17 cells in EAN spleens. Furthermore, we also found that administration of ginkgolides significantly decreased the levels of interferon (IFN)-γ and interleukin-12 (IL)-12 in GBS patients.

CONCLUSIONS

Our results suggested that ginkgolides ameliorated the clinical score of EAN through down-regulating the proportions of Th 17 cells. Ginkgolides also suppressed inflammation response by decreasing pro-inflammatory cytokines IFN-γ and IL-12, suggesting ginkgolides had potential therapeutic effects on GBS patients and EAN in the future.

The Neuroimmunology of Guillain-Barré Syndrome and the Potential Role of an Aging Immune System

Guillain-Barré syndrome (GBS) is a paralyzing autoimmune condition affecting the peripheral nervous system (PNS). Within GBS there are several variants affecting different aspects of the peripheral nerve. In general, there appears to be a role for T cells, macrophages, B cells, and complement in initiating and perpetuating attacks on gangliosides of Schwann cells and axons. Of note, GBS has an increased prevalence and severity with increasing age. In addition, there are alterations in immune cell functioning that may play a role in differences in GBS with age alongside general age-related declines in reparative processes (e.g., delayed de-differentiation of Schwann cells and decline in phagocytic ability of macrophages). The present review will explore the immune response in GBS as well as in animal models of several variants of the disorder. In addition, the potential involvement of an aging immune system in contributing to the increased prevalence and severity of GBS with age will be theorized.

Th17 cells and their cytokines serve as potential therapeutic target in experimental autoimmune neuritis

BACKGROUND

Accumulating evidence has pointed that T helper 17 cells and their cytokines are pathogenic in Guillain-Barré syndrome (GBS). However, little is known concerning the IL-17 expression change trend during the whole course of disease, and whether drugs specially targeting Th17 cells or their cytokines have potential effects on experimental autoimmune neuritis (EAN) is uncertain.

METHODS

We explored the IL-17 and receptor-related orphan receptor-gamma-t (RORγt) expression change trends in EAN rats to identify the stage of effect of Th17 pathway in EAN, and further, we investigated the effect of RORγt inhibitors by assessing clinical score, histological staining, and IL-17 and RORγt expression change trends in serum and tissues.

RESULTS

The expression level of IL-17 and RORγt in serum and tissues increased with the progression of the disease in the EAN group and decreased after the disease reaching its peak. RORγt-IN-1 treatment strikingly reduced the neurological deficits by ameliorating inflammatory cell infiltration, deceased the serum IL-17 and RORγt levels, and further downregulated the expression of IL-17 and RORγt mRNA in spleen, lymphnodes, and sciatic nerve.

CONCLUSIONS

Th17 cells and their cytokines are closely associated with the onset of GBS and the novel RORγt inhibitors may be prospective strategies in treating GBS.

Beneficial or Harmful Role of Macrophages in Guillain-Barré Syndrome and Experimental Autoimmune Neuritis

Guillain-Barré syndrome (GBS), an immune-mediated demyelinating peripheral neuropathy, is characterized by acute weakness of the extremities and areflexia or hyporeflexia. Experimental autoimmune neuritis (EAN) is a common animal model for GBS, which represents a CD4+ T cell-mediated inflammatory autoimmune demyelination of the peripheral nervous system (PNS), and is used to investigate the pathogenic mechanism of GBS. It has been found that macrophages play a critical role in the pathogenesis of both GBS and EAN. Macrophages have been primarily classified into two major phenotypes: proinflammatory macrophages (M1) and anti-inflammatory macrophages (M2). The two different macrophage subsets M1 and M2 may play a decisive role in initiation and development of GBS and EAN. However, recently, it has been indicated that the roles of macrophages in immune regulation and autoimmune diseases are more complex than those suggested by a simple M1-M2 dichotomy. Macrophages might exert either inflammatory or anti-inflammatory effect by secreting pro- or anti-inflammatory cytokines, and either inducing the activation of T cells to mediate immune response, resulting in inflammation and demyelination in the PNS, or promoting disease recovery. In this review, we summarize the dual roles of macrophages in GBS and EAN and explore the mechanism of macrophage polarization to provide a potential therapeutic approach for GBS in the future.

Beneficial or Harmful Role of Macrophages in Guillain-Barré Syndrome and Experimental Autoimmune Neuritis

Guillain-Barré syndrome (GBS), an immune-mediated demyelinating peripheral neuropathy, is characterized by acute weakness of the extremities and areflexia or hyporeflexia. Experimental autoimmune neuritis (EAN) is a common animal model for GBS, which represents a CD4⁺ T cell-mediated inflammatory autoimmune demyelination of the peripheral nervous system (PNS), and is used to investigate the pathogenic mechanism of GBS. It has been found that macrophages play a critical role in the pathogenesis of both GBS and EAN. Macrophages have been primarily classified into two major phenotypes: proinflammatory macrophages (M1) and anti-inflammatory macrophages (M2). The two different macrophage subsets M1 and M2 may play a decisive role in initiation and development of GBS and EAN. However, recently, it has been indicated that the roles of macrophages in immune regulation and autoimmune diseases are more complex than those suggested by a simple M1-M2 dichotomy. Macrophages might exert either inflammatory or anti-inflammatory effect by secreting pro- or anti-inflammatory cytokines, and either inducing the activation of T cells to mediate immune response, resulting in inflammation and demyelination in the PNS, or promoting disease recovery. In this review, we summarize the dual roles of macrophages in GBS and EAN and explore the mechanism of macrophage polarization to provide a potential therapeutic approach for GBS in the future.

Beneficial or Harmful Role of Macrophages in Guillain-Barré Syndrome and Experimental Autoimmune Neuritis

Guillain-Barré syndrome (GBS), an immune-mediated demyelinating peripheral neuropathy, is characterized by acute weakness of the extremities and areflexia or hyporeflexia. Experimental autoimmune neuritis (EAN) is a common animal model for GBS, which represents a CD4⁺ T cell-mediated inflammatory autoimmune demyelination of the peripheral nervous system (PNS), and is used to investigate the pathogenic mechanism of GBS. It has been found that macrophages play a critical role in the pathogenesis of both GBS and EAN. Macrophages have been primarily classified into two major phenotypes: proinflammatory macrophages (M1) and anti-inflammatory macrophages (M2). The two different macrophage subsets M1 and M2 may play a decisive role in initiation and development of GBS and EAN. However, recently, it has been indicated that the roles of macrophages in immune regulation and autoimmune diseases are more complex than those suggested by a simple M1-M2 dichotomy. Macrophages might exert either inflammatory or anti-inflammatory effect by secreting pro- or anti-inflammatory cytokines, and either inducing the activation of T cells to mediate immune response, resulting in inflammation and demyelination in the PNS, or promoting disease recovery. In this review, we summarize the dual roles of macrophages in GBS and EAN and explore the mechanism of macrophage polarization to provide a potential therapeutic approach for GBS in the future.

Differences in peripheral myelin antigen-specific T cell responses and T memory subsets in atypical versus typical CIDP

Background

Chronic inflammatory demyelinating polyneuropathy (CIDP) is presented by a large heterogeneity of clinical phenotypes. Around 50% of patients suffer from typical CIDP and show better therapy response than atypical variants. The goal of our study was to search for cellular immunological differences in typical versus atypical CIDP in comparison to controls.

Methods

We evaluated 26 (9 typical, 17 atypical) patients with mainly active-unstable CIDP using clinical and immunological examinations (enzyme-linked immunospot assay ELISPOT, fluorescence-activated cell sorting FACS) in comparison to 28 healthy, age-matched controls (HC). Typical or atypical CIDP measurements were compared with HC using Kruskal-Wallis test.

Results

Atypical CIDP patients showed increased frequencies of T cell subsets, especially CD4+ effector memory T cells (TEM) and CD4+ central memory T cells (TCM) as well as a tendency of higher T cell responses against the peripheral myelin antigens of PMP-22, P2, P0 and MBP peptides compared to typical CIDP. Searching for novel auto-antigens, we found that T cell responses against P0 180-199 as well as MBP 82-100 were significantly elevated in atypical CIDP patients vs. HC.

Conclusions

Our results indicate differences in underlying T cell responses between atypical and typical CIDP characterized by a higher peripheral myelin antigen-specific T cell responses as well as a specific altered CD4+ memory compartment in atypical CIDP. Larger multi-center studies study are warranted in order to characterize T cell auto-reactivity in atypical CIDP subgroups in order to establish immunological markers as a diagnostic tool.

An Animal Model of Modic Changes by Embedding Autogenous Nucleus Pulposus inside Subchondral Bone of Lumbar Vertebrae

The establishment of Modic changes (MCs) in animal model was vital for research of MCs. Fifty-four rabbits were divided into a sham group, a muscle embedment group (ME group) and nucleus pulposus (NP) embedment group (NPE group). In the NPE group, the discs were exposed by the lumbar anterolateral surgical approach. A needle was used to puncture the L5 vertebral body close to the endplate. NP was extracted by a syringe from L1/2 intervertebral discs and then injected into the drilled hole of subchondral bone. The muscle embedment group and sham group had the same procedure and drill method as the NP embedment group. Some pieces of muscle were put into the hole in the ME group, but nothing was put into the hole in the sham group. After the operation, MRI scan and molecular biology tests were applied. The signal changes were found in the NPE group; while the sham group and the ME group showed no significant signal change. Histological observation confirmed that there was abnormal tissue proliferation in imbed site. High expression of IL-4, IL-17 and IFN-γ were detected in the NPE group. The embedment of NP into subchondral bone can create an animal model of MCs.

Bowman-Birk inhibitor concentrate suppresses experimental autoimmune neuritis via shifting macrophages from M1 to M2 subtype

BACKGROUND

In the present study, we investigated the immuno-regulatory and therapeutic effects of Bowman-Birk inhibitor concentrate (BBIC) on experimental autoimmune neuritis (EAN), an animal model of Guillain-Barré syndrome (GBS) in human.

METHODS

EAN in Lewis rats induced by inoculation with peripheral nerve myelin P0 protein peptide 180-199 (P0 peptide) was treated with BBIC at two different therapeutic regimens.

RESULTS

Our data indicated that the administration of BBIC daily orally effectively inhibited and ameliorated the clinical and pathological signs of EAN. The suppression of EAN was associated with an insufficiency of autoreactive T cells, as reflected by inhibited P0 peptide-specific mononuclear cell proliferation and decreased in CD4 and CD8T cells infiltrating into the peripheral nervous system (PNS). BBIC might mediate its therapeutic effects by shifting macrophages from M1 to M2 subtype as evidenced by increasing Arg-1, CD206 and IL-10 and inhibiting IFN-γ, TNF-α, IL-12, iNOS and CD40 expressions on macrophages as well as enhancing anti-inflammatory cytokines IL-4 and IL-10 and decreasing inflammatory cytokines, IFN-γ, TNF-α and IL-17 in the PNS.

CONCLUSION

Our results suggest that BBIC may have therapeutic potential in human GBS and other autoimmune diseases in the future.

Biomarkers of Guillain-Barré Syndrome: Some Recent Progress, More Still to Be Explored

Guillain-Barré syndrome (GBS), the axonal subtype of which is mainly triggered by C. jejuni with ganglioside-mimicking lipooligosaccharides (LOS), is an immune-mediated disorder in the peripheral nervous system (PNS) accompanied by the disruption of the blood-nerve barrier (BNB) and the blood-cerebrospinal fluid barrier (B-CSF-B). Biomarkers of GBS have been extensively explored and some of them are proved to assist in the clinical diagnosis and in monitoring disease progression as well as in assessing the efficacy of immunotherapy. Herein, we systemically review the literature on biomarkers of GBS, including infection-/immune-/BNB, B-CSF-B, and PNS damage-associated biomarkers, aiming at providing an overview of GBS biomarkers and guiding further investigations. Furthermore, we point out further directions for studies on GBS biomarkers.

Mitigated Tregs and augmented Th17 cells and cytokines are associated with severity of experimental autoimmune neuritis

Experimental autoimmune neuritis (EAN), an animal model of human Guillain-Barré syndrome, has long been considered as a T helper (Th) 1 cell-mediated autoimmune disorder. However, deficiency of IFN-γ, a signature Th1 cytokine, aggravated EAN, with features of elevated production of IL-17A, despite an alleviated systemic Th1 immune response. We hypothesized that Th17 cells and their cytokines might play a pathogenic role in EAN. To further clarify the roles of these Th and regulatory T cell (Treg) cytokines in the pathogenesis of EAN and their interrelationship, we investigated the expression of Th1/Th2/Th17/Treg cytokines in EAN in this study. We found that the levels of Th17 cells and IL-17A in cauda equina (CE)-infiltrating cells and splenic mononuclear cells (MNCs) as well as in serum paralleled the disease evolution, which increased progressively during the initiation stage and reached higher value at the peak of EAN. The same pattern was also noticed for the expression of IL-22. The diverse expression profiles of FoxP3, IL-17 receptors A and C were seen in CE-infiltrating cells and splenic MNCs in EAN. These findings indicate a major pro-inflammatory role of Th17 cells and IL-17A in the pathogenesis of EAN. Therapeutic interventions may be focused upon inhibiting Th17 cells and their cytokines in the early phase of EAN, so as to delay and suppress clinical signs of the disease, which has relevance for future studies on pathogenesis and treatment of GBS in humans.

Circulating Th17, Th22, and Th1 cells are elevated in the Guillain-Barré syndrome and downregulated by IVIg treatments

The Guillain-Barré syndrome (GBS) is considered a T helper 1 (Th1) cells-mediated acute inflammatory peripheral neuropathy. However, some changes in GBS could not be explained completely by Th1 cells pathogenic role. Recently, Th17 cells have been identified and can mediate tissue inflammation and autoimmune response. Therefore, a study on the role of Th17 and Th22 cells and their cytokines in GBS is necessary for exploring the pathogenesis of GBS. Here, we detected the frequency of Th1, Th17, and Th22 cells by using 4-color flow cytometry and we detected the plasma levels of IL-17 and IL-22 by ELISA in GBS patients, relapsing-remitting multiple sclerosis patients at the acute phase of relapse, viral encephalitis or meningitis patients and healthy controls. Our data showed that the frequency of circulating Th1, Th17, and Th22 cells was significantly increased in GBS patients. The plasma levels of IL-17 and IL-22 in GBS and relapsing-remitting multiple sclerosis at the acute phase of relapse were also markedly elevated. Enhanced circulating Th22 cells were correlated with GBS severity. Intravenous immunoglobulin therapy downregulated Th17, and Th22 cells and the plasma levels of IL-17 and IL-22 in GBS patients. Th17 and Th22 cells may be involved in the pathogenesis of GBS, and intravenous immunoglobulin mediates therapeutic effects by downregulating these cells and their cytokines.

Update on Guillain-Barré syndrome

Understanding of Guillain-Barré syndrome (GBS) has progressed substantially since the seminal 1916 report by Guillain et al. Although Guillain, Barré, and Strohl summarised the syndrome based on observations of two French infantrymen, 2012 saw the beginning of an ambitious collaborative study designed to collect detailed data from at least 1,000 patients worldwide (IGOS, www.gbsstudies.org/about-igos). Progress has been made in many areas even since GBS was last reviewed in this journal in 2009. GBS subsequently received prominent attention in light of concerns regarding H1N1 influenza vaccinations, and several large-scale surveillance studies resulted. Despite these developments, and promising pre-clinical studies, disease-modifying therapies for GBS have not substantially altered since intravenous immunoglobulin was introduced over 20 years ago. In other areas, management has improved. Antibiotic prophylaxis in ventilated patients reduces respiratory tract infection, thromboprophylaxis has reduced the risk of venous thromboembolism, and there is increasing awareness of the benefit of high-intensity rehabilitation. This article highlights some of the interesting and thought-provoking developments of the last 3 years, and is based on a plenary lecture given at the 2012 Peripheral Nerve Society (PNS) meeting.

Bi(o)communications among peripheral blood fractions: a focus on NK and NKT cell biology in rheumatoid arthritis

Rheumatoid Arthritis (RA) is an autoimmune disease with unknown pathophysiology involving many interwoven signalling cascades. ROS, NK and NKT cells might be crucial in the disease severity of RA of which the role of NK and NKT cells are controversial in literature. However, the role of oxidative stress, its impact on NK and NKT cell immunobiology and disease activity (DAS28) is largely unknown. Therefore, we studied the role of oxidative stress and NK cell subsets in the pathogenesis of RA. The state of oxidative stress in various peripheral blood fractions, percentage NK and NKT cell expression, their altered apoptotic signaling pathways involving mitochondrial membrane potential, FAS associated death domain (FADD) mediated pathways and DNA damage were analyzed. Results indicated a state of profound oxidative stress in the peripheral blood of RA patients where percentage of NK and NKT cell subsets diminished while ROS levels increased. The depolarized mitochondrial membrane potential, FAS, FASL and active caspase-3 positive NK and NKT cell subsets were considerably elevated in patients. The DNA damage, assessed as percentage of DNA in comet tail, was significantly elevated. Findings of the present work indicate increased apoptosis of peripheral NK and NKT cells in the diseased condition. PBMC and RBC are the major sites of enhanced oxidative stress. The state of oxidative stress and altered immunobiology of NK and NKT cells strongly correlated with Disease activity score. The present study strongly supports the protective role of NK cell subsets in the pathogenesis of RA.

NOTCH signaling in immune-mediated bone marrow failure of aplastic anemia

Severe aplastic anemia is a rare bone marrow failure disease with the majority of cases caused by aberrant immune destruction of blood progenitors. Although the Th1-mediated pathology of aplastic anemia is well-described, the molecular mechanisms that drive disease progression remain ill-defined. The NOTCH signaling pathway mediates Th1 differentiation in the presence of polarizing cytokines, an action requiring enzymatic processing of NOTCH receptors by γ- secretase. We used a mouse model of aplastic anemia to demonstrate that expression both of intracellular NOTCH1 (NOTCH1(IC)) and T-BET, a key transcription factor regulating Th1 differentiation, were increased in T cells in the spleen and bone marrow during active disease. Conditionally deleting NOTCH1 or administering γ-secretase inhibitors (GSI) in vivo, attenuated disease and rescued mice from lethal bone marrow failure. In peripheral T cells from patients with untreated aplastic anemia, NOTCH1(IC) was significantly elevated and was detected at the TBX21 promoter, showing NOTCH1 directly regulates the gene encoding T-BET. Treating patients' cells ex vivo with GSI lowered NOTCH1(IC) levels, decreased the level of NOTCH1 detectable at the TBX21 promoter, and also decreased T-BET expression, indicating NOTCH1 signaling is responsive to GSI during active disease. Collectively, these results identify NOTCH1 signaling as a primary driver of Th1-mediated pathogenesis in aplastic anemia and may represent a novel target for therapeutic intervention.

Roles of T helper 17 cells and interleukin-17 in neuroautoimmune diseases with emphasis on multiple sclerosis and Guillain-Barré syndrome as well as their animal models

The identification of T helper 17 (Th17) cells challenges the Th1/Th2 paradigm of the immune response and invites intensive exploration of their mechanisms and functions in the field of autoimmune diseases, host defense, allergy, etc. The collective data have shown that transforming growth factor-β (TGF-β), interleukin (IL)-6, IL-1β, IL-21, and IL-23 are involved in the differentiation program of Th17 cells. The transcription factors RORγT, STAT3, RORγ, RORα, and IRF4 exert regulatory effects on the development of Th17 cells. Among the Th17-related effector cytokines, such as IL-17, IL-17F, IL-21, and IL-22, IL-17 is regarded as a key cytokine to induce inflammatory responses. This review outlines the cytokines and transcription factors involved in the differentiation of Th17 cells and their effector functions, with specific focus on the roles of Th17 cells and IL-17 in neuroautoimmune diseases, especially in multiple sclerosis and Guillain-Barré syndrome, as well as in their animal models, experimental autoimmune encephalomyelitis and experimental autoimmune neuritis.

Interferon gamma suppresses collagen-induced arthritis by regulation of Th17 through the induction of indoleamine-2,3-deoxygenase

C57BL/6 mice are known to be resistant to the development of collagen-induced arthritis (CIA). However, they show a severe arthritic phenotype when the Ifng gene is deleted. Although it has been proposed that IFN-γ suppresses inflammation in CIA via suppressing Th17 which is involved in the pathogenesis of CIA, the exact molecular mechanism of the Th17 regulation by IFN-γ is poorly understood. This study was conducted to 1) clarify that arthritogenic condition of IFN-γ knockout (KO) mice is dependent on the disinhibition of Th17 and 2) demonstrate that IFN-γ-induced indoleamine2,3dioxgenase (IDO) is engaged in the regulation of Th17. The results showed that the IFN-γ KO mice displayed increased levels of IL-17 producing T cells and the exacerbation of arthritis. Also, production of IL-17 by the splenocytes of the IFN-γ KO mice was increased when cultured with type II collagen. When Il17 was deleted from the IFN-γ KO mice, only mild arthritis developed without any progression of the arthritis score. The proportion of CD44^highCD62L^low memory-like T cells were elevated in the spleen, draining lymph node and mesenteric lymph node of IFN-γ KO CIA mice. Meanwhile, CD44^lowCD62L^high naïve T cells were increased in IFN-γ and IL-17 double KO CIA mice. When Th17 polarized CD4+ T cells of IFN-γ KO mice were co-cultured with their own antigen presenting cells (APCs), a greater increase in IL-17 production was observed than in co-culture of the cells from wild type mice. In contrast, when APCs from IFN-γ KO mice were pretreated with IFN-γ, there was a significant reduction in IL-17 in the co-culture system. Of note, pretreatment of 1-methyl-DL- tryptophan, a specific inhibitor of IDO, abolished the inhibitory effects of IFN-γ. Given that IFN-γ is a potent inducer of IDO in APCs, these results suggest that IDO is involved in the regulation of IL-17 by IFN-γ.

Divergent effects of T cell costimulation and inflammatory cytokine production on autoimmune peripheral neuropathy provoked by Aire deficiency

Chronic inflammatory demyelinating polyneuropathy results from autoimmune destruction of the peripheral nervous system and is a component of the multiorgan autoimmunity syndrome that results from Aire gene mutations in humans. In parallel, peripheral nervous system autoimmunity resembling chronic inflammatory demyelinating polyneuropathy develops spontaneously in NOD mice with a partial loss of Aire function (NOD.Aire(GW/+) mice) and is a T cell-mediated disease. In this study, we analyze how key aspects of T cell activation and function modulate disease development in Aire-deficient mice. We show that genetic ablation of the Th1 cytokine IFN-γ completely prevents clinical and electrophysiological evidence of neuropathy in NOD.Aire(GW/+) mice. IFN-γ deficiency is associated with absence of immune infiltration and decreased expression of the T cell chemoattractant IP-10 in sciatic nerves. Thus, IFN-γ is absolutely required for the development of autoimmune peripheral neuropathy in NOD.Aire(GW/+) mice. Because IFN-γ secretion is enhanced by B7-CD28 costimulation of T cells, we sought to determine the effects of these costimulatory molecules on neuropathy development. Surprisingly, B7-2 deficiency accelerated neuropathy development in NOD.Aire(GW/+) mice, and Ab blockade of both B7-1 and B7-2 resulted in fulminant, early-onset neuropathy. Thus, in contrast to IFN-γ, B7-2 alone and B7-1/B7-2 in combination function to ameliorate neuropathy development in NOD.Aire(GW/+) mice. Together, these findings reveal distinct and opposing effects of the T cell costimulatory pathway and IFN-γ production on the pathogenesis of autoimmune peripheral neuropathy.

Elevated levels of cerebrospinal fluid and plasma interleukin-37 in patients with Guillain-Barré syndrome

AIMS. Interleukin-37 (IL-37) is an anti-inflammatory cytokine. This study aims to investigate the concentrations of plasma and cerebrospinal fluid (CSF) IL-37 in patients with Guillain-Barré Syndrome (GBS).

METHODS

The levels of plasma and CSF IL-37, IL-17A, IFN- γ , and TNF- α in 25 GBS patients and 20 healthy controls (HC) were determined by enzyme-linked immunoabsorbent assay and flow cytometric bead array assay, respectively. The values of clinical parameters in the patients were also measured.

RESULTS

The concentrations of plasma IL-37, IL-17A, IFN- γ , and TNF- α and CSF IL-37 and IL-17A in patients at the acute phase of GBS were significantly higher than those in the HC. The levels of plasma IL-37, IL-17A, IFN- γ , and TNF- α were positively correlated in those patients, and the levels of CSF IL-37 and IL-17A as well as the levels of plasma TNF- α were correlated positively with the GBS disability scale scores (GDSs) in those patients. Treatment with intravenous immunoglobulin significantly reduced the levels of plasma IL-37, IL-17A, IFN- γ , and TNF- α in the drug-responding patients.

CONCLUSIONS

Our findings indicate higher levels of plasma and CSF IL-37 and IL-17A and other proinflammatory cytokines in patients with GBS.

IL-17 and IL-22 in cerebrospinal fluid and plasma are elevated in Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) is an acute autoimmune-mediated inflammatory demyelinating disease that causes rapidly progressing paralysis and occasionally respiratory failure. We hypothesized that interleukin (IL)-17 and IL-22 are elevated in GBS and participate in the autoimmune inflammatory response of GBS. We used sandwich enzyme-linked immunosorbent assay (ELISA) to measure the IL-17 and IL-22 levels in the CSF, and plasma from 22 GBS patients at the acute phase and 18 healthy controls (HC). The results show that CSF and plasma levels of IL-17 and IL-22 are elevated in GBS patients compared with HC. IL-17 and IL-22 levels in CSF, respectively, are correlated with GBS disability scale scores (GDSs). Meanwhile, IL-17 and IL-22 levels in CSF, IL-22 in CSF, and plasma of GBS patients have positive correlation, respectively. The increased levels of IL-17 and IL-22 in CSF may be explained by the disruption of blood-brain barrier (BBB) and peripheral nervous system (PNS) local inflammation in GBS. Meanwhile, the elevated levels of these two cytokines in plasma suggest the activation of Th17 and Th22 cells in the systemic immune response of GBS. Our data provide preliminary evidence that GBS is associated with high levels of IL-17 and IL-22 in CSF and plasma. These cytokines display pathogenic potential and may serve as useful biomarkers for GBS.

Attenuated EAN in TNF-α deficient mice is associated with an altered balance of M1/M2 macrophages

The role of tumor necrosis factor (TNF)-α and its receptors in neuroautoimmune and neuroinflammatory diseases has been controversial. On the basis of our previous studies, we hereby aimed to further clarify TNF-α's mechanism of action and to explore the potential role of TNF-α receptor (TNFR)1 as a therapeutic target in experimental autoimmune neuritis (EAN). EAN was induced by immunization with P0 peptide 180-199 in TNF-α knockout (KO) mice and anti-TNFR1 antibodies were used to treat EAN. Particularly, the effects of TNF-α deficiency and TNFR1 blockade on macrophage functions were investigated. The onset of EAN in TNF-α KO mice was markedly later than that in wild type (WT) mice. From day 14 post immunization, the clinical signs of TNF-α KO mice were significantly milder than those of their WT counterparts. Further, we showed that the clinical severity of WT mice treated with anti-TNFR1 antibodies was less severe than that of the control WT mice receiving PBS. Nevertheless, no difference with regard to the clinical signs of EAN or inflammatory infiltration in cauda equina was seen between TNF-α KO and WT mice with EAN after blockade of TNFR1. Although TNF-α deficiency did not alter the proliferation of lymphocytes in response to either antigenic or mitogenic stimuli, it down-regulated the production of interleukin (IL)-12 and nitric oxide (NO), and enhanced the production of IL-10 in macrophages. Increased ratio of regulatory T cells (Tregs) and reduced production of interferon (IFN)-γ in cauda equina infiltrating cells, and elevated levels of IgG2b antibodies against P0 peptide 180-199 in sera were found in TNF-α KO mice with EAN. In conclusion, TNF-α deficiency attenuates EAN via altering the M1/M2 balance of macrophages.