Jeong-Eun Kwon

IL-17-mediated mitochondrial dysfunction impairs apoptosis in rheumatoid arthritis synovial fibroblasts through activation of autophagy.

Fibroblast-like synoviocytes (FLSs) are a major cell population of the pannus that invades cartilage and bone in rheumatoid arthritis (RA). FLS resistance to apoptosis is a major characteristic of RA. The aims of this study were to investigate the effects of interleukin-17 (IL-17) and IL-17-producing T helper (Th17) cells on resistance to apoptosis in FLSs from RA patients (RA FLSs) and their roles in mitochondrial dysfunction and autophagy. Mitochondrial function was assessed in RA FLSs and FLSs from osteoarthritis patients (OA FLSs). FLSs were treated with IL-17 and their morphological features, respiratory level and mitochondrial gene expression were measured. The effects of IL-17 and Th17 cells on the relationship between autophagy and apoptosis were evaluated by measuring the expression of apoptosis-related genes using sodium nitroprusside or 3-methyladenine. The mitochondria of FLSs isolated from RA and osteoarthritis patients displayed different morphological and physiological features. RA FLSs exhibited greater autophagosome formation and greater dysfunction of mitochondrial respiration compared with OA FLSs. IL-17 induced mitochondrial dysfunction and autophagosome formation in RA FLSs, suggesting that they were resistant to apoptosis. Autophagy-related antiapoptosis induced by IL-17 was restored by inhibition of autophagy, suggesting a relationship between mitochondrial dysfunction and cell survival in RA FLSs. Th17 cells and IL-17 increased autophagy of RA FLSs by causing mitochondrial dysfunction. Our findings suggest that, in RA, interactions between RA FLSs and Th17 cells may be involved in the tumorous growth of FLSs and the formation of pannus in joints.

Epigallocatechin-3-gallate ameliorates autoimmune arthritis by reciprocal regulation of T helper-17 regulatory T cells and inhibition of osteoclastogenesis by inhibiting STAT3 signaling

The green tea polyphenol epigallocatechin‐3‐gallate is a potent antioxidant. Here, we describe the effects of epigallocatechin‐3‐gallate on T cell differentiation and osteoclast differentiation in an animal model of arthritis. Mice with collagen‐induced arthritis were injected intraperitoneally with epigallocatechin‐3‐gallate, 3 times/wk after the primary immunization. Surface markers of T helper 17 cells and regulatory T cells were analyzed by flow cytometry. Flow cytometry, Western blotting, and enzyme‐linked immunosorbent assays were used to evaluate the effect of epigallocatechin‐3‐gallate on cell signaling in the collagen‐induced arthritis model. Epigallocatechin‐3‐gallate decreased the arthritis index and showed protective effects against joint destruction in collagen‐induced arthritis mice. The expression of cytokines, oxidative stress proteins, and phosphorylated‐signal transducer and activator of transcription‐3, 705 and 727, were significantly less in mice treated with epigallocatechin‐3‐gallate than it was in controls. Epigallocatechin‐3‐gallate reduced the expression of osteoclast markers in vitro and in vivo relative to the control, and the antiosteoclastic activity was observed in epigallocatechin‐3‐gallate–treated, interferon‐γ knockout mice. The proportion of forkhead box protein 3–positive regulatory T cells was increased in the spleens of mice treated with epigallocatechin‐3‐gallate compared with control mice, whereas the proportion of T helper 17 cells was reduced. In vitro, the expression of nuclear respiratory factor 2, heme oxygenase‐1, and extracellular signal‐regulated kinase was increased significantly by epigallocatechin‐3‐gallate. We demonstrated that the administration of epigallocatechin‐3‐gallate attenuated the symptoms of arthritis, inhibited osteoclastogenesis and T helper 17 cell activation, and increased the number of regulatory T cells. At the molecular level, the antiarthritic effects of epigallocatechin‐3‐gallate may be due to induction of phosphorylated–extracellular signal‐regulated kinase, nuclear respiratory factor 2, and heme oxygenase‐1 and inhibition of signal transducer and activator of transcription‐3 activation.

Achaete-scute complex homologue 2 accelerates the development of Sjögren’s syndrome-like disease in the NOD/ShiLtJ mouse

Achaete-scute complex homologue 2 (Ascl2) has been reported to induce the differentiation and activation of follicular helper T (TFH) cells, which are essential for development of Sjögrens syndrome (SS). This study examined whether Ascl2 plays a role in the development of SS. NOD/ShiLtJ mice were injected with an Ascl2-overexpression vector, and the infiltration of lymphocytes into salivary and lacrimal glands was assessed. The expression of inflammatory cytokines and chemoattractants for T or B cells was measured. The activation of TFH cells was assessed using a specific marker of TFH cells. Ascl2 level was also measured in SS patients. Overexpression of Ascl2 increased the expression of C-X-C chemokine receptor type 5 (CXCR5) in both salivary and lacrimal glands (p<0.0001). Overexpression of Ascl2 also increased the expression of proinflammatory cytokines and chemoattractants including interleukin 6 (IL-6), tumor necrosis factor-α, IL-8, programmed cell death 1 (PD-1), IL-21, and B-cell lymphoma 6 (Bcl-6). Overexpression of Ascl2 increased the populations of CD4+CXCR5+, CD4+ICOS+, and CD4+PD-1+ cells. The Ascl2 level was higher in peripheral blood mononuclear cells from SS patients compared with those from healthy controls. Our findings suggest that Ascl2 may play a role in the development and progression of SS and may be a therapeutic target in the treatment of SS.

Grim19 Attenuates DSS Induced Colitis in an Animal Model

DSS induced colitis is a chronic inflammatory disease characterized by inflammation in the gastrointestinal tract, which destabilizes the gut and induces an uncontrolled immune response. Although DSS induced colitis is generally thought to develop as a result of an abnormally active intestinal immune system, its pathogenesis remains unclear. Gene associated with retinoid interferon induced mortality (Grim) 19 is an endogenous specific inhibitor of STAT3, which regulates the expression of proinflammatory cytokines. In this study, we investigated the influence of GRIM19 in a DSS induced colitis mouse model. We hypothesized that Grim19 would ameliorate DSS induced colitis by altering STAT3 activity and intestinal inflammation. Grim19 ameliorated DSS induced colitis severity and protected intestinal tissue. The expression of STAT3 and proinflammatory cytokines such as IL-1β and TNF-α in colon and lymph nodes was decreased significantly by Grim19. Moreover, DSS induced colitis progression in a Grim19 transgenic mouse line was inhibited in association with a reduction in STAT3 and IL-17 expression. These results suggest that Grim19 attenuates DSS induced colitis by suppressing the excessive inflammatory response mediated by STAT3 activation.

Ssu72 attenuates autoimmune arthritis via targeting of STAT3 signaling and Th17 activation

Signal transducer and activator of transcription 3 (STAT3) orchestrates the differentiation of several cell types, including interleukin-17 (IL-17)-releasing Th17 cells. Dysregulation of Th17 cells results in chronic inflammatory responses. Ssu72 is a C-terminal domain phosphatase required for transcriptional regulation. However, the mechanism by which Ssu72 affects STAT3 activation and Th17 cell differentiation is unclear. Here, we found that Ssu72 overexpression suppresses STAT3 activation and Th17 cell responses in vitro. A systemic infusion of Ssu72 attenuates experimental autoimmune arthritis by reducing STAT3 activity and the differentiation of Th17 cells. It also reduces joint destruction, serum immunoglobulin concentrations and osteoclastogenesis but increases the number of marginal zone B cells and B10 cells. These effects are associated with reduced p-STAT3 levels and the suppression of Th17 cell formation in vivo. Based on these data, Ssu72 is related to STAT3 activation and the inflammatory response; and Ssu72 overexpression in T-cell-mediated immunity has potential utility for the treatment of autoimmune arthritis.

YinYang1 deficiency ameliorates joint inflammation in a murine model of rheumatoid arthritis by modulating Th17 cell activation

Yin Yang 1 (YY1) is a ubiquitously expressed transcription factor that functions in cooperation with various cofactors to regulate gene expression. In the immune system, YY1 enhances cytokine production and T helper (Th) 2 effector cell differentiation, resulting in the activation of inflammation. However, no studies have reported the role of YY1 in Th17 cell regulation, which is implicated in rheumatoid arthritis (RA). We investigated the expression of YY1 in Th17 cells in vitro and revealed increased levels of YY1 mRNA and protein. To elucidate the function of YY1 pathogenesis in RA, we used a collagen-induced arthritis (CIA) mouse model with YY1 deficiency. Deficiency of YY1 reduced the severity of arthritis and joint destruction. Moreover, Th17 cells were dramatically reduced in YY1-deficient mice. The cytokine interleukin (IL)-17 was decreased in YY1-deficient CD4+ T cells ex vivo and in vivo. Interestingly, the level of signal transducer and activator of transcription 3 (STAT3), tumor necrosis factor-α, IL-17, IL-6, and IL-1β were markedly decreased in YY1-deficient mice with CIA. The cytokine-inducing function of YY1 was more specific to IL-17 than to interferon-γ. YY1 plays a role in Th17 cell differentiation and RA pathogenesis. Our findings suggest that future RA therapies should target the regulatory mechanism involved in Th17 cell differentiation, in which YY1 may cooperate with the STAT3 signaling pathway.

Cucurbitacin E ameliorates acute graft-versus-host disease by modulating Th17 cell subsets and inhibiting STAT3 activation

Cucurbitacin E (CuE) is a biochemical compound found in plants that are members of the family CuE has been studied for its roles in anti-inflammation and the inhibition of angiogenesis as well as for its properties as an antioxidant. CuE is a new agent that was identified as a selective inhibitor of the signal transducer and activator of transcription 3 (STAT3)-related pathway. STAT3, a pivotal transcription factor for Th17 differentiation, is critical for T cell alloactivation in acute graft-versus-host disease (aGvHD). We investigated whether CuE attenuates the development of aGvHD through the suppression of Th17 cells. The alloreactive proliferation of mouse and human T cells was reduced by CuE treatment. CuE also decreased pro-inflammatory cytokines, such as IL-17 and IFN-γ, in alloreactive T cells. STAT3-responsive and IL-17A-promoter activities were also suppressed by CuE treatment, confirming that activated STAT3 was decreased by CuE treatment. To construct an aGvHD-induced mouse line, splenocytes and bone marrow cells from C57BL/6 mice were transplanted into BALB/c mice with complete mis-matched major histocompatibility complex molecules. CuE was administered to aGvHD animals 3 days per week via intraperitoneal injection. CuE attenuated the severity of aGvHD disease-related scores compared to the vehicle group. CuE inhibited skin inflammation and fibrosis, as evidenced by the expression of α-Sma and Col-I in aGvHD mice compared to the vehicle group. Additionally, aGvHD mice treated with CuE showed improved histopathological features in the small and large intestines, whereas the vehicle group showed collapsed villi in the small intestine and cryptic structures in the large intestine. We also observed a marked reduction of pro-inflammatory cytokines in the intestinal tissue. Collectively, our data suggest that CuE could serve as a therapeutic agent for patients with aGvHD.

Attenuation of Rheumatoid Inflammation by Sodium Butyrate Through Reciprocal Targeting of HDAC2 in Osteoclasts and HDAC8 in T Cells

Rheumatoid arthritis (RA) is a systemic autoimmune disease caused by both genetic and environmental factors. Recently, investigators have focused on the gut microbiota, which is thought to be an environmental factor that affects the development of RA. Metabolites secreted by the gut microbiota maintain homeostasis in the gut through various mechanisms [e.g., butyrate, which is one of the major metabolites of gut microbiota, exerts an anti-inflammatory effect by activating G-protein-coupled receptors and inhibiting histone deacetylases (HDACs)]. Here, we focused on the inhibition of the HDACs by butyrate in RA. To this end, we evaluated the therapeutic effects of butyrate in an animal model of autoimmune arthritis. The arthritis score and incidence were lower in the butyrate-treated group compared to the control group. Also, butyrate inhibited HDAC2 in osteoclasts and HDAC8 in T cells, leading to the acetylation of glucocorticoid receptors and estrogen-related receptors α, respectively. Additionally, control of the TH17/Treg cell balance and inhibition of osteoclastogenesis were confirmed by the changes in target gene expression. Interleukin-10 (IL-10) produced by butyrate-induced expanded Treg cells was critical, as treatment with butyrate did not affect inflammatory arthritis in IL-10-knockout mice. This immune-cell regulation of butyrate was also detected in humans. These findings suggest that butyrate is a candidate agent for the treatment of RA.

Rebamipide ameliorates atherosclerosis by controlling lipid metabolism and inflammation

Atherosclerosis is a chronic inflammatory disease caused by the accumulation of excess lipid in the aorta and the severity is regulated by T lymphocytes subsets. Rebamipide has therapeutic activity in collagen induced arthritis (CIA) by controlling the balance between T helper (Th) 17 and regulatory T (Treg) cells. In this study, we aimed to determine whether rebamipide reduces the development of atherosclerosis. To investigate the therapeutic effect of rebamipide, ApoE-KO mice fed a western diet were administered rebamipide orally for 8 weeks. Mice were sacrificed followed by the evaluation of plaque formation in the aorta or immunohistochemistry for IL-17 and Foxp3. Serum was also prepared to determine the pro-inflammatory cytokine levels. The ability of rebamipide to regulate lipid metabolism or inflammation was confirmed ex vivo. Results The oral administration of rebamipide decreased plaque formation in atherosclerotic lesions as well as the markers of metabolic disorder in ApoE-deficient mice with atherosclerosis. Pro-inflammatory cytokines were also suppressed by rebamapide. In addition, the population of Th17 was decreased, whereas Treg was increased in the spleen of rebamipide-treated ApoE deficient mice. Rebamipide also ameliorated the severity of obese arthritis and has the capability to reduce the development of atherosclerosis by controlling the balance between Th17 and Treg cells. Thus, rebamipide could be a therapeutic agent to improve the progression of inflammation in metabolic diseases.

Ursodeoxycholic acid attenuates experimental autoimmune arthritis by targeting Th17 and inducing pAMPK and transcriptional corepressor SMILE

BACKGROUND Ursodeoxycholic acid (UDCA) has been known that UDCA has prominent effects on liver, however, there is little known about its influence on autoimmune disease. Here, the benefit of UDCA on arthritis rheumatoid (RA) in vivo was tested. METHODS RA mouse were induced using collagen II (CIA, collagen induced arthritis) where the disease severity or UDCA-related signaling pathway such as AMP-activated protein kinase (AMPK) or small heterodimer partner interacting leucine zipper protein (SMILE) was evaluated by westerblot and immunohistochemical staining. Gene expression was measured by realtime-polymerase chain reaction (PCR). RESULTS The administration of UDCA effectively alleviated the arthritic score and incidence with decreased cartilage damage and lipid metabolic parameters. UDCA also suppressed the secretion of pro-inflammatory cytokines. It was confirmed that UDCA upregulated the expression of SMILE and transcriptional activity of PPARγ via controlling AMPK or p38 activity. CONCLUSIONS In the present study, the therapeutic effect of UDCA inducing SMILE through AMPK activation in rheumatoid arthritis mouse as well as other autoimmune disease was proposed.