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.

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.

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.

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.

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.

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.

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.

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.

A probiotic complex, rosavin, zinc, and prebiotics ameliorate intestinal inflammation in an acute colitis mouse model.

BACKGROUND: An altered gut microbiota balance is involved in the pathogenesis of inflammatory bowel disease (IBD), and several probiotic strains are used as dietary supplements to improve intestinal health. We evaluated the therapeutic effect of 12 probiotics in combination with prebiotics, rosavin, and zinc in the dextran sodium sulfate (DSS)-induced colitis mouse model. METHODS: The probiotic complex or the combination drug was administered orally to mice with DSS-induced colitis, and the body weight, disease activity index, colon length, and histopathological parameters were evaluated. Also, the combination drug was applied to HT-29 epithelial cells, and the expression of monocyte chemoattractant protein 1 (MCP-1) was evaluated by real-time polymerase chain reaction. RESULTS: Administration of the combination drug attenuated the severity of DSS-induced colitis. Moreover, the combination drug significantly reduced the levels of the proinflammatory cytokines tumor necrosis factor-α, interleukin (IL)-6, IL-1ß, and IL-17, and significantly increased the levels of Foxp3 and IL-10 in colon sections. Additionally, treatment with the combination drug reduced MCP-1 expression in HT-29 cells. Treatment with the combination drug decreased the levels of α-smooth muscle actin and type I collagen compared with vehicle treatment in mice with DSS-induced colitis. CONCLUSION: These results suggest that the combination of a probiotic complex with rosavin, zinc, and prebiotics exerts a therapeutic effect on IBD by modulating production of pro- and anti-inflammatory cytokines and the development of fibrosis.

Th17 and IL-17 Cause Acceleration of Inflammation and Fat Loss by Inducing α2-Glycoprotein 1 (AZGP1) in Rheumatoid Arthritis with High-Fat Diet.

Rheumatoid arthritis (RA) is a chronic autoimmune disorder that affects the joints. High-fat diet (HFD) is a risk factor for RA and is related to inflammation but responds minimally to medication. Given the association between HFD and inflammation, it is important to understand the function of inflammation-related T cells in RA with HFD. Collagen-induced arthritis (CIA), a model of RA, was induced in HFD mice by injection of collagen II, and metabolic markers and T cells were analyzed. The metabolic index and IgG assay results were higher in HFD-CIA mice than in nonfat diet-CIA mice. Numbers of inflammation-related T cells and macrophages, such as Th1 and Th17 cells and M1 macrophages, were higher in spleens of HFD-CIA mice. HFD-CIA mice had a high level of α2-glycoprotein 1 (Azgp1), a soluble protein that stimulates lipolysis. To examine the association between Azgp1 and Th17 cells, the reciprocal effects of Azgp1 and IL-17 on Th17 differentiation and lipid metabolism were measured. Interestingly, Azgp1 increased the Th17 population of splenocytes. Taken together, our data suggest that the acceleration of fat loss caused by Azgp1 in RA with metabolic syndrome is related to the increase of IL-17. Mice injected with the Azgp1-overexpression vector exhibited more severe CIA compared with the mock vector-injected mice.

NPS-1034, a novel MET inhibitor, inhibits the activated MET receptor and its constitutively active mutants.

The MET proto-oncogene product, which is the receptor for hepatocyte growth factor (HGF), has been implicated in tumorigenesis and metastatic progression. Point mutations in MET lead to the aberrant activation of the receptor in many types of human malignancies, and the deregulated activity of MET has been correlated with tumor growth, invasion, and metastasis. MET has therefore attracted considerable attention as a potential target in anticancer therapy. Here, we report that a novel MET kinase inhibitor, NPS-1034, inhibits various constitutively active mutant forms of MET as well as HGF-activated wild-type MET. NPS-1034 inhibited the proliferation of cells expressing activated MET and promoted the regression of tumors formed from such cells in a mouse xenograft model through anti-angiogenic and pro-apoptotic actions. NPS-1034 also inhibited HGF-stimulated activation of MET signaling in the presence or absence of serum. Furthermore, when tested on 27 different MET variants, NPS-1034 inhibited 15 of the 17 MET variants that exhibited autophosphorylation with nanomolar potency; only the F1218I and M1149T variants were not inhibited by NPS-1034. Notably, NPS-1034 inhibited three MET variants that are resistant to the MET inhibitors SU11274, NVP-BVU972, and PHA665752. Together, these results suggest that NPS-1034 can be used as a potent therapeutic agent for human malignancies bearing MET point mutations or expressing activated MET.

Ring finger protein 149 is an E3 ubiquitin ligase active on wild-type v-Raf murine sarcoma viral oncogene homolog B1 (BRAF).

Members of the RAF family (ARAF, BRAF, and CRAF/RAF-1) are involved in a variety of cellular activities, including growth, survival, differentiation, and transformation. An oncogene encodes BRAF, the function of which is linked to MEK activation. BRAF is the most effective RAF kinase in terms of induction of MEK/ERK activity. However, the mechanisms involved in BRAF regulation remain unclear. In the present work, we used a tandem affinity purification approach to show that RNF149 (RING finger protein 149) interacts with wild-type BRAF. The latter protein is a RING domain-containing E3 ubiquitin ligase involved in control of gene transcription, translation, cytoskeletal organization, cell adhesion, and epithelial development. We showed that RNF149 bound directly to the C-terminal kinase-containing domain of wild-type BRAF and induced ubiquitination, followed by proteasome-dependent degradation, of the latter protein. Functionally, RNF149 attenuated the increase in cell growth induced by wild-type BRAF. However, RNF149 did not bind to mutant BRAF or induce ubiquitination thereof. Thus, we show that RNF149 is an E3 ubiquitin ligase active on wild-type BRAF.

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.

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.

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.

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.

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.

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.

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.