Metformin Attenuates Monosodium-Iodoacetate-Induced Osteoarthritis via Regulation of Pain Mediators and the Autophagy-Lysosomal Pathway.

Osteoarthritis (OA) is the most common degenerative arthritis associated with pain and cartilage destruction in the elderly; it is known to be involved in inflammation as well. A drug called celecoxib is commonly used in patients with osteoarthritis to control pain. Metformin is used to treat type 2 diabetes but also exhibits regulation of the autophagy pathway. The purpose of this study is to investigate whether metformin can treat monosodium iodoacetate (MIA)-induced OA in rats. Metformin was administered orally every day to rats with OA. Paw-withdrawal latency and threshold were used to assess pain severity. Cartilage damage and pain mediators in dorsal root ganglia were evaluated by histological analysis and a scoring system. Relative mRNA expression was measured by real-time PCR. Metformin reduced the progression of experimental OA and showed both antinociceptive properties and cartilage protection. The combined administration of metformin and celecoxib controlled cartilage damage more effectively than metformin alone. In chondrocytes from OA patients, metformin reduced catabolic factor gene expression and inflammatory cell death factor expression, increased LC3Ⅱb, p62, and LAMP1 expression, and induced an autophagy-lysosome fusion phenotype. We investigated if metformin treatment reduces cartilage damage and inflammatory cell death of chondrocytes. The results suggest the potential for the therapeutic use of metformin in OA patients based on its ability to suppress pain and protect cartilage.

GRIM19 Impedes Obesity by Regulating Inflammatory White Fat Browning and Promoting Th17/Treg Balance.

Obesity, a condition characterized by excessive accumulation of body fat, is a metabolic disorder related to an increased risk of chronic inflammation. Obesity is mediated by signal transducer and activator of transcription (STAT) 3, which is regulated by genes associated with retinoid-interferon-induced mortality (GRIM) 19, a protein ubiquitously expressed in various human tissues. In this study, we investigated the role of GRIM19 in diet-induced obese C57BL/6 mice via intravenous or intramuscular administration of a plasmid encoding GRIM19. Splenocytes from wild-type and GRIM19-overexpressing mice were compared using enzyme-linked immunoassay, real-time polymerase chain reaction, Western blotting, flow cytometry, and histological analyses. GRIM19 attenuated the progression of obesity by regulating STAT3 activity and enhancing brown adipose tissue (BAT) differentiation. GRIM19 regulated the differentiation of mouse-derived 3T3-L1 preadipocytes into adipocytes, while modulating gene expression in white adipose tissue (WAT) and BAT. GRIM19 overexpression reduced diet-induced obesity and enhanced glucose and lipid metabolism in the liver. Moreover, GRIM19 overexpression reduced WAT differentiation and induced BAT differentiation in obese mice. GRIM19-transgenic mice exhibited reduced mitochondrial superoxide levels and a reciprocal balance between Th17 and Treg cells. These results suggest that GRIM19 attenuates the progression of obesity by controlling adipocyte differentiation.

Myeloid-derived suppressor cells therapy enhance immunoregulatory properties in acute graft versus host disease with combination of regulatory T cells.

BACKGROUND: Myeloid-derived suppressor cells (MDSCs) play a critical role in modulating the immune response and promoting immune tolerance in models of autoimmunity and transplantation. Regulatory T cells (Tregs) exert therapeutic potential due to their immunomodulatory properties, which have been demonstrated both in vitro and in clinical trials. Cell-based therapy for acute graft-versus-host disease (aGVHD) may enable induction of donor-specific tolerance in the preclinical setting. METHODS: We investigated whether the immunoregulatory activity of the combination of MDSCs and Tregs on T cell and B cell subset and alloreactive T cell response. We evaluated the therapeutic effects of combined cell therapy for a murine aGVHD model following MHC-mismatched bone marrow transplantation. We compared histologic analysis from the target tissues of each groups were and immune cell population by flow cytometric analysis. RESULTS: We report a novel approach to inducing immune tolerance using a combination of donor-derived MDSCs and Tregs. The combined cell-therapy modulated in vitro the proliferation of alloreactive T cells and the Treg/Th17 balance in mice and human system. Systemic infusion of MDSCs and Tregs ameliorated serverity and inflammation of aGVHD mouse model by reducing the populations of proinflammatory Th1/Th17 cells and the expression of proinflammatory cytokines in target tissue. The combined therapy promoted the differentiation of allogeneic T cells toward Foxp3 + Tregs and IL-10-producing regulatory B cells. The combination treatment control also activated human T and B cell subset. CONCLUSIONS: Therefore, the combination of MDSCs and Tregs has immunomodulatory activity and induces immune tolerance to prevent of aGVHD severity. This could lead to the development of new clinical approaches to the prevent aGVHD.

Brown adipose tissue ameliorates autoimmune arthritis via inhibition of Th17 cells.

The functions of adipose tissue are associated with autoimmune diseases, such as rheumatoid arthritis (RA). Some studies have shown that the three compositions of adipose tissue (white, brown, and beige) have different functions. Brown adipose tissue (BAT) is known to secrete several factors that differ from those in white adipose tissue. This suggests that BAT might have potential positive advantages in the physiology of autoimmune diseases. We compared the functions of collagen-induced arthritis mice-derived BAT (CIA BAT) with normal mice-derived BAT. DBA/1J mice (6-7 weeks of age) were immunized by intradermal injection at the base of the tail with 100 µg of bovine type II collagen (CII) emulsified in complete Freund's adjuvant. Immunized mice then received booster immunizations by intraperitoneal injection with 100 µg of CII in incomplete Freund's adjuvant. We transplanted CIA BAT and normal BAT into CIA recipient mice. After transplantation, we measured the functions of CIA BAT and normal BAT in mice. Normal BAT-transplanted mice showed significantly lower scores of bone damage, inflammation, and cartilage damage. The proinflammatory cytokines in normal BAT-transplanted mice, such as IL-12, IL-17, IL-6, and tumor necrosis factor-α (TNF-α), tended to decrease. Microarray analysis showed that the PI3K-AKT signaling pathway and IL-17 levels of CIA BAT tissues were significantly higher than those of normal BAT tissues. These results suggest that the transplantation of normal brown fat may have a therapeutic effect in RA patients.

Metabolic abnormalities exacerbate Sjögren's syndrome by and is associated with increased the population of interleukin-17-producing cells in NOD/ShiLtJ mice.

BACKGROUND: Sjögren's syndrome (SS) is an autoimmune disease mediated by lymphocytic infiltration into exocrine glands, resulting in progressive lacrimal and salivary destruction and dysfunctional glandular secretion. Metabolic syndrome influences the immune system. To investigate its relationship with metabolic abnormalities, we evaluated the pathogenesis of SS and the immune cell populations in non-obese diabetic NOD/ShiLtJ mice with type 1 diabetes (T1D). METHODS: To induce metabolic abnormalities, streptozotocin (STZ)-a glucosamine-nitrosourea compound that destroys pancreatic ß cells, resulting in T1D-was injected into NOD/ShiLtJ mice. The blood glucose level was measured to evaluate induction of T1D. The severity of SS was assessed by determining the body weight, salivary flow rate, and histologic parameters. The expression levels of proinflammatory factors in the salivary glands, lacrimal gland, and spleen were quantified by real-time PCR. The populations of various T- and B-cell subtypes in the peripheral blood, spleen, and salivary glands were assessed by flow cytometry. RESULTS: Induction of T1D in NOD/ShiLtJ mice increased both the severity of SS and the levels of proinflammatory cytokines in the salivary glands compared to the controls. Furthermore, the number of interleukin-17-producing immune cells in the peripheral blood, spleen, and salivary glands was increased in STZ- compared to vehicle-treated NOD/ShiLtJ mice. CONCLUSIONS: Metabolic abnormalities play an important role in the development of SS.

Inhibition of RIPK3 Pathway Attenuates Intestinal Inflammation and Cell Death of Inflammatory Bowel Disease and Suppresses Necroptosis in Peripheral Mononuclear Cells of Ulcerative Colitis Patients.

Receptor-interacting serine/threonine-protein kinase (RIPK) 3 is a member of the TNF receptor-I signaling complex and mediates necroptosis, an inflammatory cell death. Ulcerative colitis (UC) is an excessive inflammatory disease caused by uncontrolled T cell activation. The current study is aimed to determine whether RIPK3 inhibitor attenuates UC development inhibiting inflammation and necroptosis using experimental colitis mice model. Dextran sulfate sodium-induced colitis mice were administered RIPK3 inhibitor (3 mg/ml) 3 times and their tissues were analyzed by immunohistochemistry. RIPK3, mixed lineage kinase domain-like (MLKL), phosphorylated MLKL, IL-17, and CD4 in colitis patient colon tissues were detected using confocal microscopy. Protein levels were measured using immunohistochemistry and ELISA. The differentiation of Th17 cells was evaluated using flow cytometry. The expression of proinflammatory cytokines and necroptosis in peripheral blood mononuclear cells from UC patients was decreased markedly by RIPK3 inhibitor treatment. We also observed that the injection of RIPK3 inhibitor improves colitis severity and protects intestinal destruction. RIPK3 inhibitor reduced necroptosis factors and proinflammatory cytokines in the colon and consequently protected colon devastation. The expression of inflammatory mediators in experimental colitis mice splenocytes was decreased significantly by RIPK3 inhibitor treatment. These results suggest that RIPK3 inhibitor ameliorates severity of experimental colitis and reduces inflammation through the inhibition of inflammatory response and necroptosis and support RIPK3-targeting substances for treatment of UC.

A bispecific soluble receptor fusion protein that targets TNF-α and IL-21 for synergistic therapy in inflammatory arthritis.

This study was aimed at investigating the therapeutic effects of BITRAP, a bispecific fusion protein targeting TNF-α and IL-21, on the development of autoimmune arthritis in humans and mice. To verify the effects of BITRAP in human, peripheral blood mononuclear cells were cultured with BITRAP under IL-17-producing T (Th17) cell-polarizing conditions or osteoclast differentiation conditions. BITRAP treatment inhibited the production of IL-17 and vascular endothelial growth factor but increased the production of IL-10 in CD4+ T cells, as well as directly suppressed osteoclastogenesis. Collagen-induced arthritis (CIA) and IL-1R antagonist (IL-1Ra) knockout mice were treated with BITRAP. Following injection in CIA mice, BITRAP rapidly migrated into the inflamed joints and remained there for 72 hours. Application of BITRAP attenuated the severity of autoimmune arthritis in CIA and IL-1Ra knockout mice by reducing the numbers of inflammatory cytokine-expressing cells and Th17 cells and antibody secretion. Finally, BITRAP suppressed STAT3 phosphorylation, as well as production of IL-17 and TNF-α, in murine splenic CD4+ T cells. These findings suggest that BITRAP, a bispecific fusion protein targeting TNF-α and IL-21, may be an effective treatment to overcome the limitations of anti-TNF therapy for patients with rheumatoid arthritis.

Interleukin-21-mediated suppression of the Pax3-Id3 pathway exacerbates the development of Sjögren's syndrome via follicular helper T cells.

Sjögren's syndrome (SS) is a systemic autoimmune disease with severe dysfunction of glandular secretory function mediated by T and B lymphocyte infiltration into the exocrine glands, including the salivary and lacrimal glands. Follicular helper T (Tfh) cells exacerbate the disease by causing B cell hyperactivity. Inhibitor of DNA binding 3 (Id3) deficiency causes activation of Tfh cells and is known to be a clinical manifestation of human SS disease. In this study, we investigated the mechanism of action of Pax3, which is reduced in SS and can interact with Id3, in NOD/ShiLtJ mice as an animal model of SS. Treatment with interleukin (IL)-21, a major cytokine secreted from Tfh cells, suppressed Pax3 and Id3 expression via STAT3 in splenic T cells in vitro. Administration of pCMV14-3xFlag PAX3 vector improved the severity of SS by reducing the number of Tfh cells in NOD/ShiLtJ mice. Application of IL-21R-Fc increased the number of Pax3- and Id3-positive cells in the salivary glands, while reducing the proportion of Tfh cells and IL-17-producing T cells in NOD/ShiLtJ mice. The salivary glands from SS patients showed decreased levels of Pax3 or Id3 expression compared with healthy controls. Our findings regarding reinforcement of the Pax3-Id3 signal pathway may facilitate the development of novel therapeutic strategies for SS.

Suberoylanilide Hydroxamic Acid Attenuates Autoimmune Arthritis by Suppressing Th17 Cells through NR1D1 Inhibition.

Rheumatoid arthritis (RA) is a type of systemic autoimmune arthritis that causes joint inflammation and destruction. One of the pathological mechanisms of RA is known to involve histone acetylation. Although the histone deacetylase (HDAC) inhibitor suberoylanilide hydroxamic acid (SAHA) can attenuate arthritis in animal models of RA, the mechanism underlying this effect is poorly understood. This study was performed to examine whether SAHA has therapeutic potential in an animal model of RA and to investigate its mechanism of action. Collagen-induced arthritis (CIA) mice were orally administered SAHA daily for 8 weeks and examined for their arthritis score and incidence of arthritis. CD4+ T cell regulation following SAHA treatment was confirmed in splenocytes cultured under type 17 helper T (Th17) cell differentiation conditions. Clinical scores and the incidence of CIA were lower in mice in the SAHA treatment group compared to the controls. In addition, SAHA inhibited Th17 cell differentiation, as well as decreased expression of the Th17 cell-related transcription factors pSTAT3 Y705 and pSTAT3 S727. In vitro experiments showed that SAHA maintained regulatory T (Treg) cells but specifically reduced Th17 cells. The same results were obtained when mouse splenocytes were cultured under Treg cell differentiation conditions and then converted to Th17 cell differentiation conditions. In conclusion, SAHA was confirmed to specifically inhibit Th17 cell differentiation through nuclear receptor subfamily 1 group D member 1 (NR1D1), a factor associated with Th17 differentiation. The results of the present study suggested that SAHA can attenuate CIA development by inhibition of the Th17 population and maintenance of the Treg population through NR1D1 inhibition. Therefore, SAHA is a potential therapeutic candidate for RA.

Metformin improves salivary gland inflammation and hypofunction in murine Sjögren's syndrome.

BACKGROUND: Activated T and B cells participate in the development and progression of Sjögren's syndrome (SS). Metformin, a first-line anti-diabetic drug, exerts anti-inflammatory and immunomodulatory effects by activating AMPK. We investigated the therapeutic effect of metformin in non-obese diabetic (NOD)/ShiLtJ mice, an animal model of SS. METHODS: Metformin or vehicle was administered orally to the mice for 9 weeks. The salivary flow rate was measured at 11, 13, 15, 17, and 20 weeks. Histological analysis of the salivary glands from vehicle- and metformin-treated mice was conducted. CD4+ T and B cell differentiation in the peripheral blood and/or spleen was determined by flow cytometry. Serum total IgG, IgG1, and IgG2a levels were determined by enzyme-linked immunosorbent assay. RESULTS: Metformin reduced salivary gland inflammation and restored the salivary flow rate. Moreover, metformin reduced the interleukin (IL)-6, tumor necrosis factor-α, IL-17 mRNA, and protein levels in the salivary glands. Metformin reduced the Th17 and Th1 cell populations and increased the regulatory T cell population in the peripheral blood and spleen and modulated the balance between Tfh and follicular regulatory T cells. In addition, metformin reduced B cell differentiation into germinal center B cells, decreased the serum immunoglobulin G level, and maintained the balance between IL-10- and IL-17-producing B cells. CONCLUSION: Metformin suppresses effector T cells, induces regulatory T cells, and regulates B cell differentiation in an animal model of SS. In addition, metformin ameliorates salivary gland inflammation and hypofunction, suggesting that it has potential for the treatment of SS.

Metformin Augments Anti-Inflammatory and Chondroprotective Properties of Mesenchymal Stem Cells in Experimental Osteoarthritis.

Mesenchymal stem cells (MSCs) can protect against cartilage breakdown in osteoarthritis (OA) via their immunomodulatory capacities. However, the optimization strategy for using MSCs remains challenging. This study's objective was to identify the in vivo effects of metformin-stimulated adipose tissue-derived human MSCs (Ad-hMSCs) in OA. An animal model of OA was established by intra-articular injection of monosodium iodoacetate into rats. OA rats were divided into a control group and two therapy groups (treated with Ad-hMSCs or metformin-stimulated Ad-hMSCs). Limb nociception was assessed by measuring the paw withdrawal latency and threshold. Our data show that metformin increased IL-10 and IDO expression in Ad-hMSCs and decreased high-mobility group box 1 protein, IL-1ß, and IL-6 expression. Metformin increased the migration capacity of Ad-hMSCs with upregulation of chemokine expression. In cocultures, metformin-stimulated Ad-hMSCs inhibited the mRNA expression of RUNX2, COL X, VEGF, MMP1, MMP3, and MMP13 in IL-1ß-stimulated OA chondrocytes and increased the expression of TIMP1 and TIMP3. The antinociceptive activity and chondroprotective effects were greater in OA rats treated with metformin-stimulated Ad-hMSCs than in those treated with unstimulated Ad-hMSCs. TGF-ß expression in subchondral bone of OA joints was attenuated more in OA rats treated with metformin-stimulated Ad-hMSCs. Our findings suggest that metformin offers a promising option for the clinical application of Ad-hMSCs as a cell therapy for OA.

Inhibition of IL-17 ameliorates systemic lupus erythematosus in Roquinsan/san mice through regulating the balance of TFH cells, GC B cells, Treg and Breg.

Systemic lupus erythematosus (SLE) is mediated by a chronic and dysregulated inflammatory response. Interleukin (IL)-17, a proinflammatory cytokine, and T helper (Th)17 cells are associated with chronic autoimmune diseases. We hypothesized that inhibition of IL-17 would decrease the numbers of T cell subsets that function as B-cell helpers, as well as B-cell differentiation into plasma cells and autoantibody expression. The IL-17 level was increased markedly in Roquinsan/san mice. Loss of IL-17 in Roquinsan/san mice improved nephritis by downregulating immunoglobulin (Ig)G, IgG1, and IgG2a production. Formation of germinal centers (GCs), and follicular B- and T-cell differentiation was reduced, whereas the number of regulatory T (Treg) cells and immature B cells was increased, by IL-17 deficiency in Roquinsan/san mice. These results suggest that IL-17 inhibition can ameliorate SLE by inhibiting B-cell differentiation into GCs. Therefore, IL-17-producing Th17 cells show promise as a target for development of novel therapeutics for SLE.

Protein inhibitor of activated STAT3 reduces peripheral arthritis and gut inflammation and regulates the Th17/Treg cell imbalance via STAT3 signaling in a mouse model of spondyloarthritis.

BACKGROUND: Spondyloarthritis (SpA) is chronic inflammatory arthritis, and interleukin (IL)-17 is crucial in SpA pathogenesis. Type 17 helper T (Th17) cells are one of major IL-17-secreting cells. Signal transducer and activator of transcription (STAT)-3 signaling induces Th17 differentiation. This study investigated the effects of protein inhibitor of activated STAT3 (PIAS3) on SpA pathogenesis. Curdlan was injected into SKG ZAP-70W163C mice for SpA induction. METHODS: The PIAS3 or Mock vector was inserted into mice for 10 weeks. Clinical and histologic scores of the paw, spine, and gut were evaluated. The expression of IL-17, tumor necrosis factor-α (TNF-α), STAT3, and bone morphogenic protein (BMP) was measured. Confocal microscopy and flow cytometry were used to assess Th cell differentiation. RESULTS: PIAS3 significantly diminished the histologic scores of the paw and gut. PIAS3-treated mice displayed decreased expression of IL-17, TNF-α, and STAT3 in the paw, spine, and gut. BMP-2/4 expression was lower in the spines of PIAS3-treated mice. Th cell differentiation was polarized toward the upregulation of regulatory T cells (Tregs) and the downregulation of Th17 in PIAS3-treated mice. CONCLUSION: PIAS3 had beneficial effects in mice with SpA by reducing peripheral arthritis and gut inflammation. Pro-inflammatory cytokines and Th17/Treg differentiation were controlled by PIAS3. In addition, BMPs were decreased in the spines of PIAS3-treated mice. These findings suggest that PIAS3 could have therapeutic benefits in patients with SpA.

CR6-interacting factor 1 controls autoimmune arthritis by regulation of signal transducer and activator of transcription 3 pathway and T helper type 17 cells.

CR6-interacting factor 1 (CRIF1) is a nuclear protein that interacts with other nuclear factors and androgen receptors, and is implicated in the regulation of cell cycle progression and cell growth. In this study, we examined whether CRIF1 exerts an immunoregulatory effect by modulating the differentiation and function of pathogenic T cells. To this end, the role of CRIF1 in rheumatoid arthritis, a systemic autoimmune disease characterized by hyperplasia of synovial tissue and progressive destruction of articular cartilage structure by pathogenic immune cells [such as T helper type 17 (Th17) cells], was investigated. p3XFLAG-CMV-10-CRIF1 was administered to mice with collagen-induced arthritis 8 days after collagen type II immunization and the disease severity and histologic evaluation, and osteoclastogenesis were assessed. CRIF1 over-expression in mice with collagen-induced arthritis attenuated the clinical and histological signs of inflammatory arthritis. Furthermore, over-expression of CRIF1 in mice with arthritis significantly reduced the number of signal transducer and activator of transcription 3-mediated Th17 cells in the spleen as well as osteoclast differentiation from bone marrow cells. To investigate the impact of loss of CRIF1 in T cells, we generated a conditional CRIF1 gene ablation model using CD4-cre transgenic mice and examined the frequency of Th17 cells and regulatory T cells. Deficiency of CRIF1 in CD4+ cells promoted the production of interleukin-17 and reduced the frequency of regulatory T cells. These results suggest a role for CRIF1 in modulating the activities of Th17 cells and osteoclasts in rheumatoid arthritis.

Kartogenin inhibits pain behavior, chondrocyte inflammation, and attenuates osteoarthritis progression in mice through induction of IL-10.

Osteoarthritis (OA) is a major degenerative joint condition that causes articular cartilage destruction. It was recently found that enhancement of chondroclasts and suppression in Treg cell differentiation are involved in the pathogenesis of OA. Kartogenin (KGN) is a small drug-like molecule that induces chondrogenesis in mesenchymal stem cells (MSCs). This study aimed to identify whether KGN can enhance severe pain behavior and improve cartilage repair in OA rat model. Induction of OA model was loaded by IA-injection of MIA. In the OA rat model, treatment an intra-articular injection of KGN. Pain levels were evaluated by analyzing PWL and PWT response in animals. Histological analysis and micro-CT images of femurs were used to analyze cartilage destruction. Gene expression was measured by real-time PCR. Immunohistochemistry was analyzed to detect protein expression. KGN injection significantly decreased pain severity and joint destruction in the MIA-induced OA model. KGN also increased mRNA levels of the anti-inflammatory cytokine IL-10 in OA patients' chondrocytes stimulated by IL-1ß. Decreased chondroclast expression, and increased Treg cell expression. KGN revealed therapeutic activity with the potential to reduce pain and improve cartilage destruction. Thus, KGN could be a therapeutic molecule for OA that inhibits cartilage damage.

IL-1-IL-17 Signaling Axis Contributes to Fibrosis and Inflammation in Two Different Murine Models of Systemic Sclerosis.

OBJECTIVE: Systemic sclerosis (SSc) is a progressive fibrotic disease that affects the skin and internal organs. Despite evidence implicating increased interleukin-17 (IL-17) activity in SSc, the role of IL-17 in SSc remains uncertain. The purpose of this study was to investigate whether IL-17 plays a pathophysiological role in SSc in two different murine models of SSc. METHODS: Bleomycin (BLM)-induced fibrosis and chronic graft-versus-host disease (cGVHD) models were used. Histological analysis was performed using Masson's trichrome and immunohistochemical staining. Quantitative reverse transcription-polymerase chain reaction and enzyme-linked immunoassays were used to quantify the messenger RNA and protein levels of inflammatory mediators in dermal fibroblasts. RESULTS: IL-1 receptor antagonist-deficient (IL-1Ra-KO) mice were more severely affected by BLM injection, as shown by dermal and pulmonary fibrosis, compared with wild-type (WT) mice. Increased tissue fibrosis was reversed by knocking down IL-17. In vitro experiments showed that IL-1 and IL-17 exerted synergistic effects on the expression of profibrotic and inflammatory mediators. In the cGVHD model, C57BL/6 mice receiving splenocytes of IL-1Ra-KO BALB/c mice developed more severe cGVHD than did those receiving cells from WT mice. Knockdown of IL-17 in IL-1Ra-KO donor mice significantly attenuated the IL-1-induced acceleration of cGVHD severity. CONCLUSION: Targeting IL-1 and its downstream IL-17 activity may be a novel treatment strategy for inhibiting inflammation and tissue fibrosis in SSc.

Lactobacillus acidophilus ameliorates pain and cartilage degradation in experimental osteoarthritis.

Osteoarthritis (OA) is a chronic and degenerative disease that causes pain, cartilage deformation, and joint inflammation. Lactobacillus species have been used as dietary supplements to induce the production of antimicrobial and anti-inflammatory factors. The goal of this study was to determine whether Lactobacillus acidophilus ameliorates monosodium iodoacetate-induced OA. L. acidophilus showed anti-nociceptive properties and protected against cartilage destruction. It also downregulated the levels of proinflammatory cytokines and increased the levels of anti-inflammatory cytokines in the joints of OA rats. L. acidophilus additionally restored the balance between anabolic and catabolic factors in chondrocytes from OA patients. These results suggest that L. acidophilus can alleviate OA-associated pain and delay the progression of the disease by inhibiting proinflammatory cytokine production and reducing cartilage damage.

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.

Deficiency of IL-1 receptor antagonist suppresses IL-10-producing B cells in autoimmune arthritis in an IL-17/Th17-dependent manner.

Rheumatoid arthritis (RA) is a systemic autoimmune disease with CD4+ T cell infiltration and hyperplasia of synovial tissues leading to progressive destruction of articular cartilage. In addition to the central role of T cells in the pathogenesis of RA, recent reports have suggested that B cells also contribute to RA. To explore the effects of interleukin (IL)-17 on B cell development and response in excess IL-1 signaling, we generated IL-17 and IL-1 receptor antagonist (IL-1Ra) double-deficient mice via backcrossing IL-17 knockout (KO) and IL-1RaKO mice. We studied the effect of IL-17 deficiency on antibody-producing B cells and regulatory B cells in IL-1RaKO mice. Excess IL-1 signal increased the frequency of B220+ IgG+ cells and plasma cells. It also promoted the production of immunoglobulins in vitro. Moreover, IL-17 deficiency significantly enhanced the frequency of regulatory IL-10-producing regulatory B cells in IL-1RaKO mice. IL-17 deficiency ameliorated disease symptoms of inflammatory arthritis in IL-1RaKO mice by suppressing the frequency of plasma cells and antibody production while enhancing the frequency of IL-10-producing B cells. These findings suggest that IL-17 can trigger an inflammatory immune reaction by activating antibody-producing B cells while suppressing immune regulatory B cells in RA.

A20 ameliorates inflammatory bowel disease in mice via inhibiting NF-κB and STAT3 activation.

A20 is a zinc finger protein that effectively inhibits the activation of nuclear factor (NF)-κB to downregulate the expression of tumor necrosis factor-α, interleukin (IL)-1ß, and IL-17. A20 also plays a crucial role as a feedback inhibitor of the inflammatory response. Due to its inhibitory role, A20 may be useful in regulating diseases resulting from chronic inflammation and excessive pro-inflammatory cytokine production, such as colitis. Patients with colitis produce high levels of pro-inflammatory cytokines in the intestine. Therefore, this study aimed to investigate whether A20 improves experimental colitis by reducing high levels of inflammation in the intestine. An A20 overexpression vector was administered to mice by intrarectal injection after colitis induction. Histological analysis by immunohistochemistry was used to score sections of the intestine. Confocal laser scanning microscopy was used to identify the expression of IL-17 and forkhead box p (FOXP) 3 protein in spleen tissues. Protein expression induced by STAT3 and NF-κB signaling was analyzed by western blot. We found that A20 reduced the colitis activity index score and the histological score of the intestine. A20 also decreased inflammatory cytokine levels in the intestine and increased colon length. Additionally, A20 overexpression downregulated the activation of NF-kB and STAT3. A20 also reduced IL-17 expression in CD4+ T cells from spleen sections. In contrast, A20 overexpression enhanced the expression of FOXP3 in CD4+ T cells. These results suggest that A20 may inhibit the progression of colitis by decreasing inflammation via inhibition of NF-κB, phosphorylated STAT3, and IL-17.