Niclosamide suppresses the expansion of follicular helper T cells and alleviates disease severity in two murine models of lupus via STAT3.

BACKGROUND: Autoantibody production against endogenous cellular components is pathogenic feature of systemic lupus erythematosus (SLE). Follicular helper T (TFH) cells aid in B cell differentiation into autoantibody-producing plasma cells (PCs). The IL-6 and IL-21 cytokine-mediated STAT3 signaling are crucial for the differentiation to TFH cells. Niclosamide is an anti-helminthic drug used to treat parasitic infections but also exhibits a therapeutic effect on autoimmune diseases due to its potential immune regulatory effects. In this study, we examined whether niclosamide treatment could relieve lupus-like autoimmunity by modulating the differentiation of TFH cells in two murine models of lupus. METHODS: 10-week-old MRL/lpr mice were orally administered with 100 mg/kg of niclosamide or with 0.5% methylcellulose (MC, vehicle) daily for 7 weeks. TLR7 agonist, resiquimod was topically applied to an ear of 8-week-old C57BL/6 mice 3 times a week for 5 weeks. And they were orally administered with 100 mg/kg of niclosamide or with 0.5% MC daily for 5 weeks. Every mouse was analyzed for lupus nephritis, proteinuria, autoantibodies, immune complex, immune cell subsets at the time of the euthanization. RESULTS: Niclosamide treatment greatly improved proteinuria, anti-dsDNA antibody levels, immunoglobulin subclass titers, histology of lupus nephritis, and C3 deposition in MRL/lpr and R848-induced mice. In addition, niclosamide inhibited the proportion of TFH cells and PCs in the spleens of these animals, and effectively suppressed differentiation of TFH-like cells and expression of associated genes in vitro. CONCLUSIONS: Niclosamide exerted therapeutic effects on murine lupus models by suppressing TFH cells and plasma cells through STAT3 inhibition.

Metformin enhances the immunomodulatory potential of adipose-derived mesenchymal stem cells through STAT1 in an animal model of lupus.

OBJECTIVES: Mesenchymal stem cells (MSCs) are considered potential therapeutic agents for treating autoimmune disease because of their immunomodulatory capacities and anti-inflammatory effects. However, several studies have shown that there is no consistency in the effectiveness of the MSCs to treat autoimmune disease, including SLE. In this study, we investigated whether metformin could enhance the immunoregulatory function of MSCs, what mechanism is relevant, and whether metformin-treated MSCs could be effective in an animal lupus model. METHODS: Adipose-derived (Ad)-MSCs were cultured for 72 h in the presence of metformin. Immunoregulatory factors expression was analysed by real-time PCR and ELISA. MRL/lpr mice weekly injected intravenously with 1 × 106 Ad-MSCs or metformin-treated Ad-MSCs for 8 weeks. 16-week-old mice were sacrificed and proteinuria, anti-dsDNA IgG antibody, glomerulonephritis, immune complex, cellular subset were analysed in each group. RESULTS: Metformin enhanced the immunomodulatory functions of Ad-MSCs including IDO, IL-10 and TGF-ß. Metformin upregulated the expression of p-AMPK, p-STAT1 and inhibited the expression of p-STAT3, p-mTOR in Ad-MSCs. STAT1 inhibition by siRNA strongly diminished IDO, IL-10, TGF-ß in metformin-treated Ad-MSCs. As a result, metformin promoted the immunoregulatory effect of Ad-MSCs by enhancing STAT1 expression, which was dependent on the AMPK/mTOR pathway. Administration of metformin-treated Ad-MSCs resulted in significant disease activity improvement including inflammatory phenotype, glomerulonephritis, proteinuria and anti-dsDNA IgG antibody production in MRL/lpr mice. Moreover, metformin-treated Ad-MSCs inhibited CD4-CD8- T-cell expansion and Th17/Treg cell ratio. CONCLUSION: Metformin optimized the immunoregulatory properties of Ad-MSCs and may be a novel therapeutic agent for the treatment of lupus.

Intermittent Fasting Aggravates Lupus Nephritis through Increasing Survival and Autophagy of Antibody Secreting Cells in MRL/lpr Mice.

Systemic lupus erythematosus (SLE) is an autoimmune disease in which the main contributors to organ damage are antibodies against autoantigens, such as double-stranded DNA (dsDNA). Calorie restriction and intermittent fasting (IF) have been shown to improve autoimmune disease symptoms in patients and animal models. Here, we tested the hypothesis that IF might improve symptoms in MRL/lpr mice, which spontaneously develop an SLE-like disease. Groups of mice were fed every other day (IF) or provided food ad libitum (controls), and various lupus-associated clinicopathological parameters were analyzed for up to 28 weeks. Contrary to expectations, anti-dsDNA antibody levels, immune complex deposition in the kidney, and glomerular injury were higher in the IF group than the control group, although there were no differences in spleen and lymph node weights between groups. Proteinuria was also worsened in the IF group. IF also increased the abundance of B cells, plasmablasts, and plasma cells and elevated autophagy in plasma cells in the spleen and lymph nodes. Secretion of anti-dsDNA antibody by splenocytes in vitro was reduced by chloroquine-induced inhibition of autophagy. These results suggest that IF exacerbates lupus nephritis in MRL/lpr mice by increasing autoantibody immune complex formation.

Fraxinellone Attenuates Rheumatoid Inflammation in Mice.

This study aimed to evaluate the therapeutic effect of fraxinellone on inflammatory arthritis and identify the underlying mechanisms. Fraxinellone (7.5 mg/kg) or a vehicle control was injected into mice with collagen-induced arthritis (CIA). The severity of arthritis was evaluated clinically and histologically. The differentiation of CD4⁺ T cells and CD19⁺ B cells was investigated in the presence of fraxinellone. Osteoclastogenesis after fraxinellone treatment was evaluated by staining with tartrate-resistant acid phosphatase (TRAP) and by measuring the mRNA levels of osteoclastogenesis-related genes. Fraxinellone attenuated the clinical and histologic features of inflammatory arthritis in CIA mice. Fraxinellone suppressed the production of interleukin-17 and the expression of RAR-related orphan receptor γ t and phospho-signal transducer and activator of transcription 3 in CD4⁺ T cells. CD19⁺ B cells showed lower expression of activation-induced cytidine deaminase and B lymphocyte-induced maturation protein-1 after treatment with fraxinellone. The formation of TRAP-positive cells and the expression of osteoclastogenesis-related markers were reduced in the presence of fraxinellone. Inhibition of interleukin-17 and osteoclastogenesis was also observed in experiments using human peripheral mononuclear cells. Fraxinellone alleviated synovial inflammation and osteoclastogenesis in mice. The therapeutic effect of fraxinellone was associated with the inhibition of cellular differentiation and activation. The data suggests that fraxinellone could be a novel treatment for inflammatory arthritis, including rheumatoid arthritis.

Mitochondrial double-stranded RNAs as a pivotal mediator in the pathogenesis of SjÓ§gren's syndrome.

SjÓ§gren's syndrome (SS) is a systemic autoimmune disease that targets the exocrine glands, resulting in impaired saliva and tear secretion. To date, type I interferons (I-IFNs) are increasingly recognized as pivotal mediators in SS, but their endogenous drivers have not been elucidated. Here, we investigate the role of mitochondrial double-stranded RNAs (mt-dsRNAs) in regulating I-IFNs and other glandular phenotypes of SS. We find that mt-dsRNAs are elevated in the saliva and tears of SS patients (n = 73 for saliva and n = 16 for tears) and in salivary glands of non-obese diabetic mice with salivary dysfunction. Using the in-house-developed 3D culture of immortalized human salivary gland cells, we show that stimulation by exogenous dsRNAs increase mt-dsRNAs, activate the innate immune system, trigger I-IFNs, and promote glandular phenotypes. These responses are mediated via the Janus kinase 1 (JAK1)/signal transducer and activator of transcription (STAT) pathway. Indeed, a small chemical inhibitor of JAK1 attenuates mtRNA elevation and immune activation. We further show that muscarinic receptor ligand acetylcholine ameliorates autoimmune characteristics by preventing mt-dsRNA-mediated immune activation. Last, direct suppression of mt-dsRNAs reverses the glandular phenotypes of SS. Altogether, our study underscores the significance of mt-dsRNA upregulation in the pathogenesis of SS and suggests mt-dsRNAs as propagators of a pseudo-viral signal in the SS target tissue.

Programmed Death-Ligand 1 Expression Potentiates the Immune Modulatory Function Of Myeloid-Derived Suppressor Cells in Systemic Lupus Erythematosus.

Multiple studies have explored the potential role of programmed death-ligand 1 (PD-L1) as a mediator of Myeloid-derived suppressor cells (MDSCs) effects in various cancers. However, the role PD-L1 expression in MDSCs on autoimmune disease is still largely unknown.This study was undertaken to whether MDSC expressing PD-L1 have more potent immunoregulatory activity and control autoimmunity more effectively in two murine models of lupus (MRL/lpr mice and Roquinsan/san mice). The populations of MDSC were increased in peripheral blood of lupus patients. The mRNA levels of immunosuppressive molecules were profoundly decreased in MDSCs from lupus patients and mice. Co-culture with splenocytes showed that PD-L1 expressing MDSCs from control mice expand both Treg cells and regulatory B cells more potently. Infusion of PD-L1 expressing MDSCs reduced autoantibody levels and degree of proteinuria and improved renal pathology of two animal models of lupus. Moreover, PD-L1 expressing MDSCs therapy can suppress double negative (CD4-CD8-CD3+) T cells, the major pathogenic immune cells and follicular helper T cells in MRL/lpr mice, and podocyte damage. Our results indicate PD-L1 expressing MDSCs have more potent immunoregualtory activity and ameliorate autoimmunity more profoundly. These findings suggest PD-L1 expressing MDSCs be a promising therapeutic strategy targeting systemic autoimmune diseases.

Baricitinib Attenuates Autoimmune Phenotype and Podocyte Injury in a Murine Model of Systemic Lupus Erythematosus.

Objective: Baricitinib, a selective inhibitor for janus kinase (JAK) 1 and JAK2, is approved for use in rheumatoid arthritis. Systemic lupus erythematosus (SLE) is recently regarded as a potential candidate targeted by JAK inhibitors because of the relationship between its pathogenesis and JAK/signal transducer and activator of transcription (STAT) pathway-mediated cytokines such as type I interferons. The objective of this study was to determine whether baricitinib could effectively ameliorate SLE using a murine model. Methods: To investigate effects of baricitinib on various autoimmune features, especially renal involvements in SLE, eight-week-old MRL/Mp-Faslpr (MRL/lpr) mice were used as a lupus-prone animal model and treated with baricitinib for eight weeks. Immortalized podocytes and primary podocytes and B cells isolated from C57BL/6 mice were used to determine the in vitro efficacy of baricitinib. Results: Baricitinib remarkably suppressed lupus-like phenotypes of MRL/lpr mice, such as splenomegaly, lymphadenopathy, proteinuria, and systemic autoimmunity including circulating autoantibodies and pro-inflammatory cytokines. It also modulated immune cell populations and effectively ameliorated renal inflammation, leading to the recovery of the expression of structural proteins in podocytes. According to in vitro experiments, baricitinib treatment could mitigate B cell differentiation and restore disrupted cytoskeletal structures of podocytes under inflammatory stimulation by blocking the JAK/STAT pathway. Conclusions: The present study demonstrated that baricitinib could effectively attenuate autoimmune features including renal inflammation of lupus-prone mice by suppressing aberrant B cell activation and podocyte abnormalities. Thus, baricitinib as a selective JAK inhibitor could be a promising therapeutic candidate in the treatment of SLE.

Type I Interferon Increases Inflammasomes Associated Pyroptosis in the Salivary Glands of Patients with Primary Sjögren's Syndrome.

Sjögren's syndrome (SS) is a chronic and systemic autoimmune disease characterized by lymphocytic infiltration in the exocrine glands. In SS, type I IFN has a pathogenic role, and recently, inflammasome activation has been observed in both immune and non-immune cells. However, the relationship between type I IFN and inflammasome-associated pyroptosis in SS has not been studied. We measured IL-18, caspase-1, and IFN-stimulated gene 15 (ISG15) in saliva and serum, and compared whether the expression levels of inflammasome and pyroptosis components, including absent in melanoma 2 (AIM2), NLR family pyrin domain containing 3 (NLRP3), apoptosis-associated speck-like protein (ASC), caspase-1, gasdermin D (GSDMD), and gasdermin E (GSDME), in minor salivary gland (MSG) are related to the expression levels of type I IFN signature genes. Expression of type I IFN signature genes was correlated with mRNA levels of caspase-1 and GSDMD in MSG. In confocal analysis, the expression of caspase-1 and GSDMD was higher in salivary gland epithelial cells (SGECs) from SS patients. In the type I IFN-treated human salivary gland epithelial cell line, the expression of caspase-1 and GSDMD was increased, and pyroptosis was accelerated in a caspase-dependent manner upon inflammasome activation. In conclusion, we demonstrate that type I IFN may contribute to inflammasome-associated pyroptosis of the SGECs of SS patients, suggesting another pathogenic role of type I IFN in SS in terms of target tissue -SGECs destruction.

JAK-1 Inhibition Suppresses Interferon-Induced BAFF Production in Human Salivary Gland: Potential Therapeutic Strategy for Primary Sjögren's Syndrome.

OBJECTIVE: To examine whether a JAK inhibitor regulates functional responses of human salivary gland epithelial cells (SGECs) and disease parameters in an animal model of Sjögren's syndrome (SS). METHODS: Common differentially expressed genes (DEGs) were analyzed among peripheral blood mononuclear cells from patients with primary SS and other data sets, using blood and SG tissue. Validation of expression in SGs was analyzed by focus score. Inhibition of messenger RNA expression of DEGs and BAFF by filgotinib was analyzed using reverse transcription-polymerase chain reaction in primary SGECs. SG organoid cultures were used to determine the association between DEGs and BAFF via knockdown using small interfering RNAs or to determine regulation of BAFF by JAK inhibitor. Filgotinib (1.5 mg/kg) was intraperitoneally injected into 8-week-old NOD/ShiLtJ mice 3 times per week to analyze manifestations of disease. Finally, STAT signaling was assessed in human and mouse SGECs. RESULTS: Expression of the DEGs IFNG and BAFF increased in SGs from patients with primary SS, as assessed by focus score. There was a significant correlation between IFIT2 and BAFF expression. JAK inhibitor suppressed interferon (IFN)-induced transcription of DEGs and BAFF in human primary SGECs. Knockdown of DEGs or inhibition of JAK caused reduced secretion of BAFF in human SG organoid cultures. In addition, filgotinib-treated mice exhibited increased salivary flow rates and marked reductions in lymphocytic infiltration of SGs. JAK inhibitor regulated IFNα- and IFNγ-induced pSTAT-1Y701 , pSTAT-3Y705 , and protein inhibitor of activated STAT-3 (PIAS-3) in human SGECs as well as IFNγ-induced pSTAT-1Y701 , pSTAT-3S727 , and PIAS-1 in mouse SGECs. CONCLUSION: JAK inhibition controls aberrant activation of SGECs and may be a novel therapeutic approach for primary SS.

Ethyl pyruvate ameliorates inflammatory arthritis in mice.

OBJECTIVES: Ethyl pyruvate (EP) is the ethyl ester of pyruvate and has antioxidative and anti-inflammatory effects. This study aimed to evaluate the therapeutic effect of EP in inflammatory arthritis and to identify the underlying mechanisms. METHODS: Mice with collagen-induced arthritis (CIA) were treated with the vehicle control or EP at 20mg/kg, and clinical and histological analyses were performed on the animals. The differentiation of murine CD4+ T cells into T helper 17 (Th17) cells in the presence of EP was investigated in vitro. The effects of EP on osteoclastogenesis were determined by staining for tartrate-resistant acid phosphatase, and measuring the mRNA levels of osteoclastogenesis-related genes. The expression of high-mobility group box 1 (HMGB1) was evaluated after EP therapy using immunohistochemical staining and Western blotting. RESULTS: EP significantly improved the clinical and histological features of arthritis in CIA mice. EP suppressed the differentiation of CD4+ T cells into Th17 cells, and inhibited the expression of RORγt. The generation of osteoclasts and osteoclastogenic markers from murine and human monocytes was significantly reduced in the presence of EP. The expression of HMGB1 in the synovium was significantly lower in CIA mice treated with EP, compared to control CIA mice. During osteoclastogenesis, HMGB1 release from monocytes was inhibited in the presence of EP. CONCLUSIONS: EP attenuated synovial inflammation and bone destruction in the experimental arthritis model through suppression of IL-17 and HMGB-1. The data suggests that EP could be a novel therapeutic agent for the treatment of inflammatory arthritis, such as rheumatoid arthritis.