Th1 Cell-mediated Autoimmune Disease Research Articles

A mAb to SIRPα downregulates the priming of naive CD4 + T cell in Primary immune thrombocytopenia

SIRPα is a transmembrane protein that binds the protein tyrosine phosphatases SHP-1 and SHP-2 through its cytoplasmic region and is abundantly expressed on monocytes, dendritic cells, and macrophages. Studies recently showed that SIRPα is essential for priming of CD4 + T cells by DCs and for development of Th17 cell-mediated autoimmune diseases. We have now further evaluated the importance of SIRPα and that of its ligand CD47 in primary immune thrombocytopenia (ITP). In this study, we show that there was a low expression state of SIRPα on the surface of monocytes. Treatment of cells culture from ITP patients with a mAb to SIRPα that blocks the binding of SIRPα to CD47 downregulated the ITP response. The abilities of monocytes from ITP patients to stimulate an allogenic MLR were reduced. The proliferation of, and production of IL-2, by CD4 + T cells from ITP patients were inhibited, the Treg cell numbers and the production of IL-10 pairs were upregulated, and the production of TGF-β not was inhibited, by a mAb to SIRPα. Moreover, a mAb to SIRPα, the expression of HLA-DR and CD86 were markedly inhibited and the expression of CD80 was slightly upregulated, on the surface of CD14 + monocytes from ITP patients as compared with healthy subjects. However, blockade of SIRPα increased the secretion of TLR-dependent cytokines TNF-α, IL-6 and IL-1β by PBMCs, which may be considered as a reserve in response to danger signals. These results suggest that SIRPα on monocytes is essential for the priming of naive T cells and the development of ITP. Therefore, SIRPα is a potential therapeutic target for ITP and other autoimmune diseases.

M6A mRNA modification potentiates Th17 functions to inflame autoimmunity.

N6-methyladenosine (m6A), the most common and abundant epigenetic RNA modification, governs mRNA metabolism to determine cell differentiation, proliferation and response to stimulation. m6A methyltransferase METTL3 has been reported to control T cell homeostasis and sustain the suppressive function of regulatory T cells (Tregs). However, the role of m6A methyltransferase in other subtypes of T cells remains unknown. T helper cells 17 (Th17) play a pivotal role in host defense and autoimmunity. Here, we found that the loss of METTL3 in T cells caused serious defect of Th17 cell differentiation, and impeded the development of experimental autoimmune encephalomyelitis (EAE). We generated Mettl3f/fIl17aCre mice and observed that METTL3 deficiency in Th17 cells significantly suppressed the development of EAE and displayed less Th17 cell infiltration into central nervous system (CNS). Importantly, we demonstrated that depletion of METTL3 attenuated IL-17A and CCR5 expression by facilitating SOCS3 mRNA stability in Th17 cells, leading to disrupted Th17 cell differentiation and infiltration, and eventually attenuating the process of EAE. Collectively, our results highlight that m6A modification sustains Th17 cell function, which provides new insights into the regulatory network of Th17 cells, and also implies a potential therapeutic target for Th17 cell mediated autoimmune disease.

Identification of Small Molecule Inhibitors of a Mir155 Transcriptional Reporter in Th17 Cells

MicroRNA miR-155 is an important regulatory molecule in the immune system and is highly expressed and functional in Th17 cells, a subset of CD4+ T helper cells which are key players in autoimmune diseases. Small molecules that can modulate miR-155 may potentially provide new therapeutic avenues to inhibit Th17 cell-mediated autoimmune diseases. Here, we present a novel high-throughput screening assay using primary T cells from genetically engineered Mir155 reporter mice, and its use to screen libraries of small molecules to identify novel modulators of Th17 cell function. We have discovered a chemical series of (E)-1-(phenylsulfonyl)-2-styryl-1H-benzo[d] imidazoles as novel down-regulators of Mir155 reporter and cytokine expression in Th17 cells. In addition, we found that FDA approved antiparasitic agents belonging to the ‘azole’ family also down-regulate Mir155 reporter and cytokine expression in Th17 cells, and thus could potentially be repurposed to treat Th17-driven immunopathologies.

Uncovering New Challenges in Targeting Glycolysis to Treat Th17 Cell-Mediated Autoimmunity.

Targeting glycolysis in T helper 17 (Th17) cells presents an attractive opportunity to treat Th17 cell-mediated autoimmune diseases such as multiple sclerosis (MS). Pyruvate kinase isoform 2 (PKM2) is a glycolytic enzyme expressed in T cells infiltrating the central nervous system in a mouse model of MS, suggesting PKM2 modulation could provide a new avenue for MS therapeutics. In a recent article in Science Signaling, Seki et al. show that pharmacological modulation of PKM2 alters but does not ameliorate disease in a mouse model of MS. These results warrant further consideration of PKM2 modulators to treat Th17 cell-mediated autoimmunity.

UCP3 reciprocally controls CD4+ Th17 and Treg cell differentiation.

Uncoupling proteins (UCPs) are members of the mitochondrial anion carrier superfamily that can mediate the transfer of protons into the mitochondrial matrix from the intermembrane space. We have previously reported UCP3 expression in thymocytes, mitochondria of total splenocytes and splenic lymphocytes. Here, we demonstrate that Ucp3 is expressed in peripheral naive CD4+ T cells at the mRNA level before being markedly downregulated following activation. Non-polarized, activated T cells (Th0 cells) from Ucp3-/- mice produced significantly more IL-2, had increased expression of CD25 and CD69 and were more proliferative than Ucp3+/+ Th0 cells. The altered IL-2 expression observed between T cells from Ucp3+/+ and Ucp3-/- mice may be a factor in determining differentiation into Th17 or induced regulatory (iTreg) cells. When compared to Ucp3+/+, CD4+ T cells from Ucp3-/- mice had increased FoxP3 expression under iTreg conditions. Conversely, Ucp3-/- CD4+ T cells produced a significantly lower concentration of IL-17A under Th17 cell-inducing conditions in vitro. These effects were mirrored in antigen-specific T cells from mice immunized with KLH and CT. Interestingly, the altered responses of Ucp3-/- T cells were partially reversed upon neutralisation of IL-2. Together, these data indicate that UCP3 acts to restrict the activation of naive T cells, acting as a rheostat to dampen signals following TCR and CD28 co-receptor ligation, thereby limiting early activation responses. The observation that Ucp3 ablation alters the Th17:Treg cell balance in vivo as well as in vitro suggests that UCP3 is a potential target for the treatment of Th17 cell-mediated autoimmune diseases.

Role of the IL-23-T-bet/GATA3 Axis for the Pathogenesis of Ulcerative Colitis.

Ulcerative colitis (UC) has been considered a Th2- and Th17-related disease. However, anti-IL-12/23 p40 antibody, which blocks Th1 and Th17 cell induction and maintenance, has shown efficacy in treating UC, suggesting that UC might not be a prototypical Th2 and Th17 cell-mediated autoimmune disease. To verify how the immune responses in UC patients interact with each other, we analyzed the cytokine expression and transcription factors involved in the Th1, Th2, and Th17 responses. The mucosal expression of 19 cytokines and transcription factors related to Th1, Th2, and Th17 cells, as well as Tregs, were measured by quantitative polymerase chain reaction using endoscopic biopsy specimens from inflamed colons of UC patients. A correlation analysis between the cytokines and transcription factors was conducted. The characteristic cytokine profile in UC patients has two immune response clusters: Th17-related responses and Th1-/Th2-related responses. IL-23 showed a weaker association with Th17 cell-related cytokines and transcription factor RORC and a much stronger correlation with T-bet and GATA3. In the high-IL-23-expression group, the rate of chronic continuous type was higher and the remission rate lower than in the low-IL-23-expression group. IL-23 may be a very important cytokine for evaluating the UC disease condition, as the expression of IL-23 is associated with certain clinical characteristics of UC patients. A unique association between IL-23 and T-bet/GATA3 might play a key role in the pathogenesis of UC.

Inhibition of Glycolysis in Pathogenic TH17 Cells through Targeting a miR -21-Peli1-c-Rel Pathway Prevents Autoimmunity.

It is well known that some pathogenic cells have enhanced glycolysis; the regulatory network leading to increased glycolysis are not well characterized. In this study, we show that CNS-infiltrated pathogenic TH17 cells from diseased mice specifically upregulate glycolytic pathway genes compared with homeostatic intestinal TH17 cells. Bioenergetic assay and metabolomics analyses indicate that in vitro-derived pathogenic TH17 cells are highly glycolytic compared with nonpathogenic TH17 cells. Chromatin landscape analyses demonstrate TH17 cells in vivo that show distinct chromatin states, and pathogenic TH17 cells show enhanced chromatin accessibility at glycolytic genes with NF-κB binding sites. Mechanistic studies reveal that miR-21 targets the E3 ubiquitin ligase Peli1-c-Rel pathway to promote glucose metabolism of pathogenic TH17 cells. Therapeutic targeting c-Rel-mediated glycolysis in pathogenic TH17 cells represses autoimmune diseases. These findings extend our understanding of the regulation TH17 cell glycolysis in vivo and provide insights for future therapeutic intervention to TH17 cell-mediated autoimmune diseases.

Metabolic regulation of TH17 cells

IL-17-producing TH17 cells have been associated with autoimmune diseases such as multiple sclerosis (MS), psoriasis, Crohn’s disease, and ulcerative colitis (Han et al., 2015), many of which lack effective therapies. Identifying effective approaches to selectively suppress TH17 cell development and function represents a legitimate strategy to cure these autoimmune disorders. TH17 cell differentiation requires rewiring of their metabolic program, transition from the oxidative phosphorylation-dominant catabolic phenotype in quiescent naïve T cells to glucose metabolism-orchestrated anabolic phenotype including lipogenesis. Here, we provide a focused review on the glycolytic-lipogenic pathway in TH17 development and pathogenicity. These studies reveal several metabolic checkpoints with specific regulation of TH17 cells (but not other T cell lineages), manifesting potential therapeutic opportunities to TH17 cell-mediated autoimmune diseases.

Discovery of N-indanyl benzamides as potent RORγt inverse agonists

The retinoic acid receptor-related orphan receptor-gamma-t (RORγt) is a promising therapeutic target for treatment of Th17 cell-mediated autoimmune diseases. Based on a scaffold hopping/conformational restriction strategy, a series of N-indanyl benzamides as novel RORγt inverse agonists was discovered. Exploration of structure-activity relationship on the piperazine ring, benzoyl moiety and cyclopentyl moiety of N-indanyl benzamides 2a and 2d led to identification of potent RORγt inverse agonists. Compound 5c with (S)-enantiomer was found having an IC50 of 153.7 nM in Fluorescence Resonance Energy Transfer (FRET) assay, and an IC50 of 47.1 nM in mouse Th17 cell differentiation assay, which represents a promising starting point for developing potent small molecule RORγt inverse agonists. Binding modes of the two enantiomers 5c and 5d in RORγt ligand binding domain were also discussed.

Differences in Intercellular Communication During Clinical Relapse and Gadolinium-Enhanced MRI in Patients With Relapsing Remitting Multiple Sclerosis: A Study of the Composition of Extracellular Vesicles in Cerebrospinal Fluid.

This study was designed based on the hypothesis that changes in both the levels and surface marker expression of extracellular vesicles (EVs) isolated from the cerebrospinal fluid (CSF) may be associated with the clinical form, disease activity, and severity of multiple sclerosis (MS). The analyzes were performed on subjects affected by MS or other neurological disorders. EVs, which were isolated by ultracentrifugation of CSF samples, were characterized by flow cytometry. A panel of fluorescent antibodies was used to identify the EV origin: CD4, CCR3, CCR5, CD19, and CD200, as well as isolectin IB4. The Mann–Whitney U-test and Kruskal–Wallis test were used for statistical analyzes. EVs isolated from the CSF were more abundant in patients with progressive MS and in those with a clinically isolated syndrome than in all the other groups examined. Furthermore, an important change in the number of EVs and in their surface marker expression occurred during active phases of MS [i.e., clinical relapses and the presence of enhancing lesions on magnetic resonance imaging (MRI)]. In particular, the number of CSF-EVs increased in patients affected by MS during clinical relapse; this finding was associated with a decrease in the number of CD19+/CD200+ (naïve B cells) EVs. These markers are expressed by immature and naïve B lymphocytes, and to the best of our knowledge, this double staining has never been associated with MS, but their reduction has been observed in patients with another type of Th1 cell-mediated autoimmune disease. In contrast, the presence of lesions in the brain and spine on gadolinium-enhanced MRI was associated with an increase in the numbers of CCR3+/CCR5+ (subset of CD8 memory T cells), CD4+/CCR3+ (Th2 cells), and CD4+/CCR5+ (Th1 cells) CSF-EVs. Two points are worth emphasizing: (i) the data obtained in this study confirm that CSF-EVs represent a potentially promising tool to identify biomarkers specific for different phases of MS; and (ii) Considering the role of EVs in intercellular communication, our results provide some insights that improve our understanding of the relationships among some of the cell types that are mainly involved in MS pathogenesis (e.g., lymphocytes, glia, and neurons).

Lumican Inhibits the pathogenicity of murine encephalitic TH17 cells

Abstract TH17 cells play an essential role in the development of both human multiple sclerosis and animal experimental autoimmune encephalomyelitis (EAE). Nevertheless, it is not well understood how the pathogenicity of TH17 cells is controlled in the autoimmune neuro-inflammation. In vitro, we found Lumican (Lum), an extracellular matrix (ECM) protein, is selectively expressed by TH17 cells among tested murine TH subsets. Lum-deficiency leads to earlier onset and enhanced severity of experimental autoimmune encephalomyelitis. This enhanced disease in Lum-deficient mice is associated with increased production of IL-17 and IL-21 and decreased TH17 cell apoptosis. Dysregulation in cytokine production appears to be specific to TH17 cells as TH1 and TH2 cell polarization and/or cytokine production were unaltered. Furthermore, adoptive transfer of MOG-specific TH17 cells derived from Lum-deficient mice led to earlier onset and increased severity of disease compared to controls highlighting a TH17 cell-intrinsic effect of Lum. Taken together, our results suggest that Lum negatively regulates encephalitic TH17 cells, implicating a potential therapeutic pathway in TH17 cell-mediated autoimmune and inflammatory diseases.

The nuclear receptor REV-ERBα modulates Th17 cell-mediated autoimmune disease

Abstract T helper 17 cells (Th17) play an important role in controlling extracellular bacteria and yeast infections; however, dysregulated Th17 response can lead to detrimental autoimmune diseases such as multiple sclerosis. Th17 cell differentiation relies on IL6/TGF-β-induced expression of retinoic acid receptor-related orphan nuclear receptor RORγt, which is able to induce Th17 effector cytokines such as IL17A. Therefore, antagonizing RORγt activity may prove to be one of the therapeutic strategies for ameliorating Th17-mediated inflammation. Here we identify REV-ERBα (encoded by Nr1d1), a member of the nuclear hormone receptor family, as a transcriptional repressor that antagonizes RORγt-induced Il17a expression. Both RORγt and REV-ERBα bind to the same ROR response element (RORE) in Il17a promoter region. Elevated expression of REV-ERBα prevents RORγt binding to RORE and reduces Il17a expression. Furthermore, treatment with a synthetic REV-ERBα agonist, SR9009, significantly delays the onset and impedes the progression of experimental autoimmune encephalomyelitis (EAE), a Th17-mediated autoimmune disease. These results suggest that modulating REV-ERBα activity holds therapeutic potential for treatment of Th17 cell-mediated autoimmune diseases.

A Novel Combination of Docosahexaenoic Acid, All-Trans Retinoic Acid, and 1, 25-Dihydroxyvitamin D3 Reduces T-Bet Gene Expression, Serum Interferon Gamma, and Clinical Scores but Promotes PPARγ Gene Expression in Experimental Autoimmune Encephalomyelitis.

Vitamins are immunologically interesting due to their significant immunomodulatory activities. Experimental autoimmune encephalomyelitis (EAE) is one of the most commonly used experimental models for studying autoimmune disorder in multiple sclerosis (MS). The aim of this study was to evaluate the protective and ameliorative effects of novel combination of all-trans retinoic acid (ATRA), 1,25-dihydroxyvitamin D3 (D3), and docosahexaenoic acid (DHA) on EAE-specific determinants and target gene expressions. Mice were randomly categorized into three groups before EAE induction [non-treated EAE (Group E), treated EAE (Group T), and healthy mice (Group H)]. Encephalomyelitis was induced in female C57BL/6 mice by subcutaneous immunization using commercial kits. Preceding day of EAE induction, combination of ATRA, D3, and DHA was administered with a single IP injection every 48h and continued until day 26. Findings of present study showed that administration of vitamins A, D, and DHA significantly decreased average clinical scores, cumulative EAE score, and EAE incidence in Group T, compared to Group E (p values <0.001). Interferon γ secretion in serum and T-bet mRNA expression in splenocytes were significantly reduced (p=0.004, p=0.029, respectively) while PPARγ mRNA expression was significantly increased in Group T compared to Group E (p=0.021). These findings highlighted that ATRA, D3, and DHA combination modulated PPARγ and T-bet gene expression and resulted in decrease in Th1 response and lymphocyte invasion into the central nervous system (CNS) and resultant inflammation. In conclusion, the results of this study suggested the potential use of this intervention in treatment and/or prevention of EAE/MS and probably other Th1 cell-mediated autoimmune diseases.

Vitamin D modulates different IL-17-secreting T cell subsets in multiple sclerosis patients

Vitamin D deficiency is an environmental risk factor for MS, a Th17 cell-mediated autoimmune disease that results in demyelination in the CNS. Therefore, we aimed to evaluate the ability of in vitro 1,25(OH)2D in modulating different Th17 cell subsets in MS patients in remission phase. In the present study, the production of Th17-related cytokines (IL-1β, IL-6, IL-17, IL-22), as well as GM-CSF, was significantly higher in cell cultures from MS patients than in healthy subjects (HS). The 1,25(OH)2D reduced all pro-inflammatory cytokines essayed, mainly those released from HS cell cultures. The proportion of both IL-17+IFN-γ+ (CD4+ and CD8+) T cells and IL-17+IFN-γ−CD8+ T cells was positively related with neurological disorders, determined by EDSS score. The addition of 1,25(OH)2D reduced not only these pathogenic T cell subsets but elevated the percentage of IL-10-secreting conventional (FoxP3+CD25+CD127−CD4+) and non-conventional (IL-17+) regulatory-like T cells. Taken together, the results indicate that the active form of vitamin D should benefit MS patients by attenuating the percentage of pathogenic T cells. This effect could be direct and/or indirect, by enhancing classical and non-classical regulatory T cells.

MDSCs enhance Th17 differentiation and disease progression through arginase-1 production in patients with systemic lupus erythematosus

Abstract Expansion of myeloid-derived suppressor cells (MDSCs) has been documented in some murine models and patients with autoimmune diseases, but the exact role of MDSCs in this process remains largely unknown. Although MDSCs are supposed to be immunosuppressive, previous studies have shown that these cells may also enhance Th17 responses via an IL-1-dependent mechanism in murine autoimmune models, such as experimental autoimmune encephalomyelitis (EAE) and collagen-induced arthritis (CIA). However, the role of MDSCs in the development of autoimmune responses in human remains largely unknown. Current study investigates this question in patients with systemic lupus erythematosus (SLE). We found that patients with active SLE (n=32) had a significant increase in HLA-DR−CD11b+CD33+ MDSCs, in the peripheral blood compared to healthy controls (HCs; n=25). The frequency of MDSCs was positively correlated with the level of serum arginase-1 (Arg-1) activity, Th17 responses and disease severity in SLE patients. Consistently, in comparison with MDSCs from HCs, MDSCs from SLE patients exhibited significantly elevated Arg-1 production, and increased potential to promote Th17 differentiation in vitro in an Arg-1-dependent manner that is likely mediated by multiple mechanisms involving RORgt, RORa and mTOR. Moreover, in a humanized SLE model, MDSCs were essential for the induction of Th17 responses and the associated renal injuries and the effect of MDSCs was Arg-1-dependent. Our data provide direct evidence demonstrating a pathogenic role for MDSCs in human SLE, and suggests that targeting MDSCs or Arg-1 may offer novel therapeutic strategies for the treatment of SLE and other Th17 cell-mediated autoimmune diseases.

Salvianolic acid B ameliorates CNS autoimmunity by suppressing Th1 responses

Experimental autoimmune encephalomyelitis (EAE), the animal model of multiple sclerosis (MS), is a Th1 and Th17 cell-mediated CNS autoimmune disease. Therefore, immune regulation is a key target for therapy. Salvianolic acid B (Sal B) is a major water-soluble bioactive component of the famous traditional Chinese medicine Salvia miltiorrhiza, which is notable for its anti-oxidative and anti-inflammatory effects. Thus Sal B, by impairing Th1 or Th17 responses in EAE/MS, might ameliorate the crippling symptoms. Here we show that the intraperitoneal administration of 30mg/kg Sal B daily for 14 days after the onset of MOG-induced EAE in mice effectively reduced its severity. Additionally, Sal B treatment downgraded the infiltration of inflammatory cells, limited astrogliosis and blocked Th1 responses other than that of Th17. These results indicated that Sal B may serve as an effective therapeutic agent for MS/EAE by inhibiting Th1 cell responses.

Bacillus-derived poly-γ-glutamic acid reciprocally regulates the differentiation of T helper 17 and regulatory T cells and attenuates experimental autoimmune encephalomyelitis

Forkhead box protein 3 (FoxP3(+)) regulatory T (T(reg)) cells and interleukin (IL)-17-producing T helper 17 (Th17) cells have opposing effects on autoimmunity, as the former are crucial for maintaining self-tolerance while the latter play a key role in precipitating inflammatory autoimmune diseases. Here we report that Bacillus-derived poly-γ-glutamic acid (γ-PGA) signals naive CD4(+) T cells to promote the selective differentiation of T(reg) cells and to suppress the differentiation of Th17 cells. The γ-PGA inducibility of FoxP3 expression was due partially to transforming growth factor (TGF)-β induction through a Toll-like receptor (TLR)-4/myeloid differentiating factor 88 (MyD88)-dependent pathway. However, this pathway was dispensable for γ-PGA suppression of Th17 differentiation. γ-PGA inhibited IL-6-driven induction of Th17-specific factors including signal transducer and activator of transcription-3 (STAT-3) and retinoic acid-related orphan receptor γt (RORγt) while up-regulating the STAT-3 inhibitor suppressor of cytokine signalling 3 (SOCS3). Importantly, in vivo administration of γ-PGA attenuated the symptoms of experimental autoimmune encephalomyelitis and at the same time reduced Th17 cell infiltrates in the central nervous system. Thus, we have identified the microbe-associated molecular pattern, γ-PGA, as a novel regulator of autoimmune responses, capable of promoting the differentiation of anti-inflammatory T(reg) cells and suppressing the differentiation of proinflammatory Th17 cells. These findings draw attention to the potential of γ-PGA for treating Th17 cell-mediated autoimmune diseases.

IFN-γ induced by IL-12 administration prevents diabetes by inhibiting pathogenic IL-17 production in NOD mice

Interleukin 12 (IL-12) is a pivotal Th1-associated cytokine and a potent immunoregulatory molecule. However, the role of IL-12 in inducing immune tolerance that prevents insulitis and inhibits type 1 diabetes (T1D) remains unknown. The aim of this study was to investigate whether intermittent administration of IL-12 could prevent the development of T1D in nonobese diabetic (NOD) mice. We examined whether IL-12 treatment prevented diabetes by injecting different doses of IL-12 into NOD mice and compared the incidence of diabetes and insulitis in NOD mice with the incidence in control mice. Furthermore, we investigated the potential mechanisms of IL-12-mediated prevention of diabetes and insulitis. The expression of pro-inflammatory and immunoregulatory cytokines was measured before and following therapeutic administration of IL-12 in NOD mice. Our data demonstrated that both the absolute number and the function of DCs were impaired in NOD mice and that the levels of the Th17-associated pro-inflammatory cytokines, IL-1β, IL-6 and IL-23, were elevated in NOD mice compared with age-matched BALB/c and C57BL/6 mice. However, treatment of NOD mice with IL-12 suppressed insulitis and increased the number of healthy islets, and the levels of IL-17, IL-1β, IL-6 and IL-23 were significantly decreased. Moreover, IL-12 treatment of NOD mice induced the secretion of IFN-γ, a potent inhibitor of Th17 cells. These data indicated that intermittent administration of IL-12 prevented diabetes by inducing IFN-γ, suppressing the pathogenic IL-17-producing cells and reducing the expression of Th17-associated pro-inflammatory cytokines. Our results suggest a promising strategy for the treatment of human T1D and other Th17 cell-mediated autoimmune diseases.

The Mechanism of Sesame Oil in Ameliorating Experimental Autoimmune Encephalomyelitis in C57BL/6 Mice

Experimental autoimmune encephalomyelitis (EAE) is a Th1 cell-mediated autoimmune disease of the CNS that serves as an animal model for multiple sclerosis (MS). The study investigated the effectiveness of treatment with sesame oil on the development of EAE. EAE was induced in 8 week old C57BL/6 mice with an emulsion of MOG35-55. Therapy with sesame oil (4 mL/kg/day as oral gavage) was started on day 3 before the immunization. IFN-gamma and IL-10 production from cultured spleen supernatants were determined by the ELISA method. The results showed that daily oral gavage of sesame oil significantly reduced the clinical symptoms of EAE in C57BL/6 mice. In addition, sesame oil-treated mice displayed a significantly delayed disease onset. Mononuclear cells isolated from spleen of sesame oil-treated mice showed a significant decrease in the production of IFN-gamma compared with control mice (p = 0.001). IL-10 production was also enhanced in splenic mononuclear cells in sesame oil-treated mice. The ratio of IFN-gamma to IL-10 in sesame oil-treated EAE mice was significantly less than in non-treated EAE mice (p = 0.01). This report indicates that sesame oil therapy protected mice from developing EAE by reducing IFN-gamma secretion. Thus, sesame oil treatment may be effective in MS patients by immunomodulating the Th1 immune response.

IDO Upregulates Regulatory T Cells via Tryptophan Catabolite and Suppresses Encephalitogenic T Cell Responses in Experimental Autoimmune Encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a Th1 and Th17 cell-mediated autoimmune disease of the CNS. IDO and tryptophan metabolites have inhibitory effects on Th1 cells in EAE. For Th17 cells, IDO-mediated tryptophan deprivation and small molecule halofuginone-induced amino acid starvation response were shown to activate general control nonrepressed 2 (GCN2) kinase that directly or indirectly inhibits Th17 cell differentiation. However, it remains unclear whether IDO and tryptophan metabolites impact the Th17 cell response by mechanisms other than the GCN2 kinase pathway. In this article, we show that IDO-deficient mice develop exacerbated EAE with enhanced encephalitogenic Th1 and Th17 cell responses and reduced regulatory T cell (Treg) responses. Administration of the downstream tryptophan metabolite 3-hydroxyanthranillic acid (3-HAA) enhanced the percentage of Tregs, inhibited Th1 and Th17 cells, and ameliorated EAE. We further demonstrate that Th17 cells are less sensitive to direct suppression by 3-HAA than are Th1 cells. 3-HAA treatment in vitro reduced IL-6 production by activated spleen cells and increased expression of TGF-β in dendritic cells (DCs), which correlated with enhanced levels of Tregs, suggesting that 3-HAA-induced Tregs contribute to inhibition of Th17 cells. By using a DC-T cell coculture, we found that 3-HAA-treated DCs expressed higher levels of TGF-β and had properties to induce generation of Tregs from anti-CD3/anti-CD28-stimulated naive CD4(+) T cells. Thus, our data support the hypothesis that IDO induces the generation of Tregs via tryptophan metabolites, such as 3-HAA, which enhances TGF-β expression from DCs and promotes Treg differentiation.