IL-23 modulated myelin-specific T cells induce EAE via an IFNγ driven, IL-17 independent pathway

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory demyelinating disease of the central nervous system (CNS) mediated by myelin-reactive CD4⁺ T cells. An unresolved issue that has important clinical implications concerns the cytokines produced by myelin-reactive T cells that determine their pathogenicity. Initially, IL-12 polarized, IFNγ producing Th1 cells were thought to be essential for the development of EAE. More recently, IL-23 polarized, IL-17 producing Th17 cells have been highlighted as critical encephalitogenic effectors. There is growing evidence that parallel autoimmune pathways can result in common clinical and histopathological endpoints. In the current study, we describe a form of EAE induced by the transfer of IL-23 modulated CD4⁺ T cells into IL-17 receptor (IL-17R) deficient hosts. We found that IL-23 stimulates myelin-reactive T cells to produce both IFNγ and IL-17. Surprisingly, in this model the development of EAE is IFNγ dependent. Our findings illustrate a novel mechanism by which IL-23 promotes encephalitogenicity and they further expand the spectrum of autoreactive T cells capable of mediating inflammatory demyelinating disease of the CNS.     

Interleukin-17-secreting T cells in neuromyelitis optica and multiple sclerosis during relapse

Growing evidence suggests that interleukin (IL)-17 and IL-17-secreting CD4⁺T (Th17) cells are involved in the pathogenic mechanisms of multiple sclerosis (MS). IL-17-secreting CD8⁺T cells were recently identified as a novel subset of CD8⁺T cells. We aimed to analyze the role of Th17 and IL-17 secreting CD8⁺T cells in the pathogenesis of neuromyelitis optica (NMO) as well as MS. Fourteen patients with NMO, 20 with MS and 16 control participants (CTL) were enrolled between November 2008 and December 2009. The proportion of Th17 cells and IL-17 secreting CD8⁺T cells were counted using flow cytometry, and serum levels of IL-6, IL-17, IL-21, IL-23, and transforming growth factor-beta (TGF-β) were measured by enzyme-linked immunosorbent assay. Patients with NMO had a larger proportion of Th17 cells than patients with MS (3.72% versus [vs.] 2.58%, p = 0.02) and CTL (3.72% vs. 1.36%, p < 0.001). The proportion of Th17 cells in patients with MS was also markedly higher than in the CTL (2.58% vs. 1.36%, p < 0.001). IL-17-secreting CD8⁺T cell counts in NMO patients were markedly higher than in MS patients (1.61% vs. 1.09%, p = 0.036) and CTLs (1.61% vs. 0.58%, p < 0.001). The proportion of IL-17-secreting CD8⁺T cells in MS patients was also higher than in CTLs (1.09% vs. 0.58%, p = 0.002). Serum IL-17 and IL-23 levels were increased in patients with NMO and MS, while serum IL-21 concentration was higher only in NMO patients compared to CTL. We concluded that Th17 cells were highly activated in patients with NMO. IL-17-secreting CD8⁺T cells were increased in patients with NMO and MS during relapse and have an important role in the pathological mechanism of NMO and MS.     

Infiltration of Th1 and Th17 cells and activation of microglia in the CNS during the course of experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a mouse model for multiple sclerosis, where disease is mediated by autoantigen-specific T cells. Although there is evidence linking CD4⁺ T cells that secrete IL-17, termed Th17 cells, and IFN-γ-secreting Th1 cells with the pathogenesis of EAE, the precise contribution of these T cell subtypes or their associated cytokines is still unclear. We have investigated the infiltration of CD4⁺ T cells that secrete IFN-γ, IL-17 or both cytokines into CNS during development of EAE and have examined the role of T cells in microglial activation. Our findings demonstrate that Th17 cells and CD4⁺ T cells that produce both IFN-γ and IL-17, which we have called Th1/Th17 cells, infiltrate the brain prior to the development of clinical symptoms of EAE and that this coincides with activation of CD11b⁺ microglia and local production of IL-1β, TNF-α and IL-6 in the CNS. In contrast, significant infiltration of Th1 cells was only detected after the development of clinical disease. Co-culture experiments, using mixed glia and MOG-specific T cells, revealed that T cells that secreted IFN-γ and IL-17 were potent activators of pro-inflammatory cytokines but T cells that secrete IFN-γ, but not IL-17, were less effective. In contrast both Th1 and Th1/Th17 cells enhanced MHC-class II and co-stimulatory molecule expression on microglia. Our findings suggest that T cells which secrete IL-17 or IL-17 and IFN-γ infiltrate the CNS prior to the onset of clinical symptoms of EAE, where they may mediate CNS inflammation, in part, through microglial activation.     

Therapeutic gene silencing with siRNA for IL-23 but not for IL-17 suppresses the development of experimental autoimmune encephalomyelitis in rats

Gene silencing with siRNAs is important as a therapeutic tool in autoimmune diseases. In this study, we administered siRNAs specific for cytokines that may be involved in pathogenesis of experimental autoimmune encephalomyelitis (EAE). siRNA specific for IL-23p19 (siRNA-IL-23) suppressed EAE almost completely, whereas siRNA-IL-17A did not modulate the clinical course. Flow cytometric analysis revealed that siRNA-IL-23 significantly reduced the proportion of both IFN-γ⁺IL-17^? Th1 and IFN-γ^?IL-17⁺ Th17 cells in the spinal cord. Consistent with this finding, siRNA-IL-23 treatment downregulated IL-12, IL-17 and IL-23 mRNAs. These findings indicate that IL-23, but not IL-17, play an important role in the development of EAE.     

Respiratory infection with a bacterial pathogen attenuates CNS autoimmunity through IL-10 induction

Infection with viral or bacterial pathogens has been linked with the development of multiple sclerosis (MS), while infection with helminth parasites has been associated protection against MS and other autoimmune diseases. Here we have used a murine model of MS, experimental autoimmune encephalomyelitis (EAE), to examine the effect of infection with the respiratory pathogen Bordetella pertussis infection on development of CNS inflammation. The data demonstrate that infection of mice with B. pertussis significantly attenuates the clinical course of EAE induced by active immunization or cell transfer. This was reflected in a significant reduction in VLA-4 and LFA-1 expression on T cells and infiltration of IL-17⁺, IFN-γ⁺ and IFN-γ⁺IL-17⁺ CD4 T cells into the CNS. Infection with B. pertussis induced IL-10 production from dendritic cells in vitro and enhanced the frequency of IL-10-producing CD25^-Foxp3^+/− CD4⁺ T cells in vivo. Furthermore, the suppressive effects of B. pertussis infection on EAE were lost in IL-10^−/− mice. Our findings demonstrate that a bacterial infection of the respiratory tract can attenuate EAE by promoting production of the anti-inflammatory cytokine IL-10 that may suppress licensing of autoaggressive T cells in the lungs, thereby preventing their migration into the CNS.     

Involvement of levels of Toll like receptor-4 in monocytes,CD4 + T-lymphocyte subsets,and cytokines in patients with immune thrombocytopenic purpura

Introduction

Toll-like receptors have been found to be associated with immune-mediated diseases but it is still not clear whether they play a role in immune thrombocytopenic purpura (ITP), especially TLR4. CD4 + T-lymphocyte abnormalities, including Th17, Th1, Th2, and regulator T cell (Treg), are considered important in ITP. There have been few studies regarding the expression of TLR4 and the relationships between TLR4 and Th17 levels in ITP.

Materials and Methods

In this study, we evaluated the expression of TLR4 in monocytes, the plasma concentrations of IL-23, IL-17 and the profiles of Th17, Th1, Th2 cells in 70 patients with ITP and 31 healthy controls. In addition, we evaluated IL-2 and Treg cells in 46 cases of 70 patients with ITP and the same 31 controls.

Results

Higher levels of TLR4 expression, higher relative numbers of Th17 and Th1 cells and lower levels of Treg cells were observed in patients when compared with controls (p = 0.001 for TLR4; p < 0.001 for Th17; p = 0.014 for Th1; p = 0.001 for Treg). The levels of IL-23 and IL-2 were increased (p = 0.022 for IL-23; p = 0.025 for IL-2), the relative levels of Th2 and concentrations of IL-17 were similar across both groups (p = 0.446 for Th2; p = 0.316 for IL-17). A significant negative correlation was observed between levels of TLR4 and Treg(r = -0.544, p < 0.001), but a significantly positive correlation was observed between IL-2 and IL-23 concentration in patients (r = 0.441, p = 0.004). Neither the correlation between TLR4 and the other CD4⁺ T cells and cytokines nor the correlation between the three cytokines and CD4+ T cells was found to be statistically significant.

Conclusions

Our data showed that TLR4, CD4 + T cells (Th1, Th17 and Treg cells) and related cytokines (IL-23, IL-2) may take part in the pathogenesis of ITP. TLR4 may play a role through the TLR4-cytokine-CD4+ T lymphocyte cell pathway.     

Dopamine favors expansion of glucocorticoid-resistant IL-17-producing T cells in multiple sclerosis

Dopamine (DA) is a neurotransmitter produced mainly in the central nervous system (CNS) that has immunomodulatory actions on T cells. As the multiple sclerosis (MS) has long been regarded as an autoimmune disease of CNS mediated by T cells, the objective of this study was to evaluate the impact of DA on in vitro functional status of T cells from relapsing–remitting (RR)–MS patients. Peripheral T-cells from RR–MS patients were activated by mitogens and cell proliferation and cytokine production were assayed by [³H]-thymidine uptake and ELISA, respectively. Our results demonstrated that DA enhanced in vitro T cell proliferation and Th17-related cytokines in MS-derived cell cultures. In addition, this catecholamine reduced Treg-related cytokines (IL-10 and TGF-β) release by activated CD4⁺ T cells. These DA-induced effects on T cells were mainly dependent on IL-6 production by both polyclonally-activated CD4⁺ T cells and LPS-stimulated monocytes. Furthermore, the production of IL-17 and IL-6 by MS-derived T cells was directly related with neurological disability (EDSS score), and the release of these cytokines was less sensitive to glucocorticoid inhibition in MS patients than in control group, mainly after DA addition. In conclusion, our data suggest that DA amplifies glucocorticoid-resistant Th17 phenotype in MS patients, and this phenomenon could be, at least in part, due to its ability to induce IL-6 production by monocytes and CD4⁺ T cells.     

Gintonin mitigates experimental autoimmune encephalomyelitis by stabilization of Nrf2 signaling via stimulation of lysophosphatidic acid receptors

Gintonin (GT), a glycolipoprotein fraction isolated from ginseng, exerts neuroprotective effects in models of neurodegenerative diseases such as Alzheimer’s disease. However, the in vivo role of GT in multiple sclerosis (MS) has not been clearly resolved. We investigated the effect of GT in myelin oligodendrocyte glycoprotein (MOG_35-55)-induced experimental autoimmune encephalomyelitis (EAE), an animal model of MS. GT alleviated behavioral symptoms of EAE associated with reduced demyelination, diminished infiltration and activation of immune cells (microglia and macrophage), and decreased expression of inflammatory mediators in the spinal cord of the EAE group compared to that of the sham group. GT reduced the percentages of CD4⁺/IFN-γ⁺ (Th1) and CD4⁺/IL-17⁺ (Th17) cells but increased the population of CD4⁺/CD25⁺/Foxp3⁺ (Treg) cells in the spinal cord, in agreement with altered mRNA expression of IFN-γ, IL-17, and TGF-ß in the spinal cord in concordance with mitigated blood–brain barrier disruption. The underlying mechanism is related to inhibition of the ERK and p38 mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-κB) pathways and the stabilization of nuclear factor erythroid 2-related factor 2 (Nrf2) via increased expression of lysophosphatidic acid receptor (LPAR) 1–3. Impressively, these beneficial effects of GT were completely neutralized by inhibiting LPARs with Ki16425, a LPAR1/3 antagonist. Our results strongly suggest that GT may be able to alleviate EAE due to its anti-inflammatory and antioxidant activities through LPARs. Therefore, GT is a potential therapeutic option for treating autoimmune disorders including MS.     

Local expression of cytokines in idiopathic inflammatory myopathies

H. Lepidi, V. Frances, D. Figarella-Branger, C. Bartoli, A. Machado-Baeta & J-F. Pellissier (1998) Neuropathology and Applied Biology , 24, 73–79
Local expression of cytokines in idiopathic inflammatory myopathies
The idiopathic inflammatory myopathies (IIM), including dermatomyositis (DM), polymyositis (PM), and inclusion body myositis (IBM), are regarded as autoimmune diseases. They are characterized by chronic lymphocytic and macrophagic infiltration in muscle tissue. Of particular importance in understanding the immune response to IIM is the specific pattern of locally produced cytokines. Frozen muscle tissues from IIM (5 DM, 3 PM, and 1 IBM) were used to investigate the cytokine responses. The RT-PCR technique was instrumental to determine the pattern of expression of pro-inflammatory (IL-1β, IL-6, TNF-α), Th1 (IFN-γ IL-2), and Th2 (IL-4) cytokines. Immunohistochemistry was also used to localize morphologically IFN-γ and IL-4. Our results show that pro-inflammatory cytokines and Th1 cytokines are mainly expressed in IIM. The accumulation of mononuclear inflammatory cells and the inflammatory syndrome in IIM are probably related in part to the production of pro-inflammatory cytokines. Moreover, the pattern of local cytokine expression is consistent with a Th1 immune response related to autoimmune diseases.     

La respuesta sistémica Th17/IL-17A aparece antes del proceso neurodegenerativo en el hipocampo de ratas expuestas a bajas dosis de ozono

IntroductionExposure to low doses of O₃ leads to a state of oxidative stress. Some studies show that oxidative stress can modulate both the CNS and systemic inflammation, which are important factors in the development of Alzheimer disease (AD).ObjectiveThis study aims to evaluate changes in the frequency of Th17-like cells (CD3⁺CD4⁺IL-17A⁺), the concentration of IL-17A in peripheral blood, and hippocampal immunoreactivity to IL-17A in rats exposed to low doses of O₃.MethodsOne hundred eight male Wistar rats were randomly assigned to 6 groups (n = 18) receiving the following treatments: control (O₃ free) or O₃ exposure (0.25 ppm, 4 hours daily) over 7, 15, 30, 60, and 90 days. Twelve animals from each group were decapitated and a peripheral blood sample was taken to isolate plasma and mononuclear cells. Plasma IL-17A was quantified using LUMINEX, while Th17-like cells were counted using flow cytometry. The remaining 6 rats were deeply anaesthetised and underwent transcardial perfusion for immunohistological study of the hippocampus.ResultsResults show that exposure to O₃ over 7 days resulted in a significant increase in the frequency of Th17-like cells and levels of IL-17A in peripheral blood. However, levels of Th17/IL-17A in peripheral blood were lower at day 15 of exposure. We also observed increased IL-17A in the hippocampus beginning at 30 days of exposure.ConclusionThese results indicate that O₃ induces a short-term, systemic Th17-like/IL-17A effect and an increase of IL-17A in the hippocampal tissue during the chronic neurodegenerative process.     

Inflammatory myopathies: evaluation and management

The inflammatory myopathies, including dermatomyositis, inclusion body myositis, and polymyositis, are poorly understood autoimmune diseases affecting skeletal muscle. Dermatomyositis is a disease mainly of skin and muscle, but may affect lung and other tissues. Proximal or generalized weakness or skin rash are the typical presenting features. Inclusion body myositis has a specific clinical pattern of weakness that generally distinguishes it from other inflammatory myopathies, with prominent involvement of wrist and finger flexors, and quadriceps. Polymyositis generally presents with proximal or generalized weakness. Typical dermatomyositis muscle pathology is quite distinct, with perivascular inflammatory cells that include plasmacytoid dendritic cells, and abnormal capillaries and perimysial perifascicular myofibers. Both inclusion body myositis and polymyositis usually have infiltration into muscle of large numbers of inflammatory cells, typically surrounding and displacing, and sometimes invading, myofibers. Inclusion body myositis is refractory to corticosteroids and to several immunomodulating therapies that have been used. Dermatomyositis and polymyositis are treated with corticosteroids and a variety of agents. Osteoporosis and opportunistic infections pose a significant risk during treatment of patients. This review discusses the clinical manifestations, pathology, and treatment approaches for the inflammatory myopathies.     

β-Lapachone ameliorization of experimental autoimmune encephalomyelitis

β-Lapachone is a naturally occurring quinine, originally isolated from the bark of the lapacho tree (Tabebuia avellanedae) which is currently being evaluated in clinical trials for the treatment of cancer. In addition, recent investigations suggest its potential application for treatment of inflammatory diseases. Multiple sclerosis (MS) is an autoimmune disorder characterized by CNS inflammation and demyelination. Reactive T cells including IL-17 and IFN-γ-secreting T cells are believed to initiate MS and the associated animal model system experimental autoimmune encephalomyelitis (EAE). IL-12 family cytokines secreted by peripheral dendritic cells (DCs) and CNS microglia are capable of modulating T-cell phenotypes. The present studies demonstrated that β-lapachone selectively inhibited the expression of IL-12 family cytokines including IL-12 and IL-23 by DCs and microglia, and reduced IL-17 production by CD4⁺ T-cells indirectly through suppressing IL-23 expression by microglia. Importantly, our studies also demonstrated that β-lapachone ameliorated the development on EAE. β-Lapachone suppression of EAE was associated with decreased expression of mRNAs encoding IL-12 family cytokines, IL-23R and IL-17RA, and molecules important in Toll-like receptor signaling. Collectively, these studies suggest mechanisms by which β-lapachone suppresses EAE and suggest that β-lapachone may be effective in the treatment of inflammatory diseases such as MS.     

Interferon beta inhibits the Th17 cell-mediated autoimmune response in patients with relapsing–remitting multiple sclerosis

Interferon (IFN)β has been used over the past decades as an effective first-line therapy against relapsing–remitting multiple sclerosis (RR MS), however its in vivo operative mechanisms of action are not fully understood. Current advances in our understanding of the development of the autoimmune response, including its induction by a recently discovered Th17 cell lineage, may allow us to identify the biomarkers of this effective therapy. Our in vitro human studies have characterized IFNβ’s immunoregulatory effects on Th17 cell differentiation. IFNβ inhibited IL-1β, IL-23 and transforming growth factor (TGF)-β (which induce Th17 cell differentiation), and induced IL-27, IL-12p35 and IL-10 (which suppress it) in dendritic cells (DCs) and B-cells. The effect on IL-1β, IL-23 and IL-27 production in DCs was mediated by the up-regulation of Toll-like receptor (TLR)7 and its downstream signaling molecules. IFNβ’s direct effect on naïve T-cells suppressed in vitro Th17 differentiation by inhibiting Th17 cell lineage markers (retinoic acid-related orphan nuclear hormone receptor (ROR)c, IL-17A, IL-23R and CCR6), and by inducing IL-10 production by CD4 cells, which constrains Th17 cell expansion. Our results have identified novel therapeutic mechanisms of IFNβ, which inhibit Th17 cell differentiation in the context of the autoimmune response in MS.     

The activation of monocyte and T cell networks in patients with bipolar disorder

Objectives

We recently described a monocyte pro-inflammatory state in patients with bipolar disorder (BD). We hypothesized that the CD4⁺T cell system is also activated and determined percentages of Th1, Th2, Th17 and CD4⁺CD25^highFoxP3⁺ regulatory T cells.

Methods

We carried out a detailed FACS analysis to determine the various T cell subsets and used frozen stored peripheral blood mononuclear cells (PBMC) of 38 BD patients (of whom we previously had tested monocytes for pro-inflammatory gene expression ( [Drexhage et al., 2010a] and [Padmos et al., 2008])) and of 22 age/gender matched healthy controls (HC). In addition the cytokines CCL2, IL-1β, IL-6, TNF-α, PTX3, IL-10, IFN-γ, IL-17A, IL-4, IL-5 and IL-22 were measured in serum.

Results

(a) Serum sCD25 levels and percentages of anti-inflammatory CD4⁺CD25^highFoxP3+ regulatory T cells were higher, the latter in BD patients <40 years of age. Percentages of Th1, Th2 and Th17 cells were normal.(b) Of the pro-inflammatory monocyte cytokines CCL2 and PTX3 were raised in serum.(c) The monocyte pro-inflammatory state and the raised percentages of CD4⁺CD25^highFoxP3⁺ regulatory T cells occurred independently from each other.(d) In BD patients positive for thyroid autoimmune disease a significantly reduced percentage of CD4⁺CD25^highFoxP3⁺ regulatory T cells was found as compared to BD patients without AITD.

Conclusion

Our data show an enhancement of pro-inflammatory monocyte and anti-inflammatory T cell forces in BD patients. A lack of anti-inflammatory T cell forces co-occurred with AITD in BD patients.     

Expression of myogenic regulatory factors and myo-endothelial remodeling in sporadic inclusion body myositis

Muscle repair relies on coordinated activation and differentiation of satellite cells, a process that is unable to counterbalance progressive degeneration in sporadic inclusion body myositis (s-IBM). To explore features of myo regeneration, the expression of myogenic regulatory factors Pax7, MyoD and Myogenin and markers of regenerating fibers was analyzed by immunohistochemistry in s-IBM muscle compared with polymyositis, dermatomyositis, muscular dystrophy and age-matched controls. In addition, the capillary density and number of interstitial CD34⁺ hematopoietic progenitor cells was determined by double-immunoflourescence staining. Satellite cells and regenerating fibers were significantly increased in s-IBM similar to other inflammatory myopathies and correlated with the intensity of inflammation (R > 0.428). Expression of MyoD, visualizing activated satellite cells and proliferating myoblasts, was lower in s-IBM compared to polymyosits. In contrast, Myogenin a marker of myogenic cell differentiation was strongly up-regulated in s-IBM muscle. The microvascular architecture in s-IBM was distorted, although the capillary density was normal. Notably, CD34⁺ hematopoietic cells were significantly increased in the interstitial compartment. Our findings indicate profound myo-endothelial remodeling of s-IBM muscle concomitant to inflammation. An altered expression of myogenic regulatory factors involved in satellite cell activation and differentiation, however, might reflect perturbations of muscle repair in s-IBM.     

Higher susceptibility to experimental autoimmune encephalomyelitis in Muc1-deficient mice is associated with increased Th1/Th17 responses

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system in which dendritic cells (DC) play an important role in the development of inflammatory responses. Recently it has been shown that Muc1, a membrane tethered glycoprotein, has an ability to suppress inflammatory responses in cultured DC. The objective of this study was to investigate the possible involvement of Muc1 in the development of MS using experimental autoimmune encephalomyelitis (EAE) in mice, a widely used animal model of MS. Our results showed that: (1) Muc1^−/− mice developed greater EAE severity compared with wild type (wt) mice, which correlated with increased numbers of Th1 and Th17 cells infiltrating into the CNS; (2) upon stimulation, splenic DC from Muc1^−/− mice produced greater amounts of IL-1β, IL-6, and IL-12 but less amounts of IL-10 compared with those from wt mice; and (3) the ability of splenic DC to differentiate antigen-specific CD4+ T cells into Th1 and Th17 cells was greater in Muc1^−/− mice compared with wt mice. We conclude that Muc1 plays an anti-inflammatory role in EAE. This is the first report demonstrating the possible involvement of Muc1 in the development of MS and might provide a potential target for immunotherapy.     

Acute toxoplasma myositis: an immunohistochemical and ultrastructural study

Summary The occurrence is reported of acute myositis in a man with meningoencephalitis due to toxoplasmosis. The ultrastructure and immunohistochemistry of a muscle biopsy of the patient were investigated. Toxoplasma organisms were not found in the muscle biopsy. The perivascular inflammatory cells in the muscle were mainly CD4⁺ T cells and the inflammatory cells in and around the muscle fibres were chiefly macrophages. Expression of major histocompatibility complex class I and II antigens was observed in the infiltrating cells and endothelial cells of the blood vessels. A small proportion of the infiltrating cells expressed interferon-. A possible role of the immune mechanism in the evolution of myositis is discussed.