Human Systemic Lupus Erythematosus Research Articles

Mesenchymal Stem Cells Induce Regulatory T-cell Population in Human SLE

Background: The mechanisms underlying peripheral disorders during systemic lupus erythematosus (SLE) were found to be shared with tolerance disorders and mediated by T-regulator (T-reg) cells. Mesenchymal stem cells (MSCs) may inhibit T-cell subset differentiation and induce the T-reg cell phenotype. However, the capacity of MSCs to promote functional T-reg cells in SLE patients remains unclear.
 Objectives: This study aimed to analyze the capacity of MSCs to induce the production of functional CD4+ CD25+ Foxp3+ T-reg cells, in vitro, under co-culture conditions with human SLE cells.
 Methods: This study used a pre- and post-test control group design. Peripheral blood mononuclear cells (PBMCs) were extracted from SLE patients at the Kariadi Hospital, and MSCs were derived from human umbilical cords (hUCs) The PBMC control group was treated with standard medium, and the treatment group was co-cultured with hUC-MSCs. After 24 hours of co-culture incubation, T-reg cells were removed from the PBMC pool, using magnetic-activated cell sorting (MACS), and the population was assessed using the trypan blue exclusion assay.
 Results: A significant increase in the population of T-reg cells was observed (P < 0.001) after 24 hours of co-culture incubation with hUC-MSCs.
 Conclusion: This study concluded that MSCs have the capacity to enhance the T-reg population in human SLE PBMCs.
 Bangladesh Journal of Medical Science Vol.19(4) 2020 p.743-748

Novel PAR2 antagonist ameliorates progression of lupus nephritis in NZB/Z F1 mice

Lupus nephritis (LN) is, the most frequent phenotype in patients with systemic lupus erythematosus (SLE), has a high rate of progression to end‐stage renal disease, even with intensive induction and maintenance therapies, approximately 20% of patients with LN progress to end‐stage renal disease. Recent evidence suggests that protease‐activated receptor‐2 (PAR2) is a therapeutic target for glomerulonephritis. In this study, we identified a novel PAR2 antagonist and evaluated the effect of the PAR2 antagonist on LN in lupus‐prone mouse model. To identify novel PAR2 antagonist, a cell‐based high‐throughput screening was performed. The effect of PAR2 antagonist on podocytes was observed in human podocyte cell line and LN was evaluated in NZB/W F1 mice. We identified punicalagin (PCG, a major polyphenol in pomegranate) as a novel potent PAR2 antagonist. In human podocyte cell line, PCG potently inhibited PAR2 (IC50 = 1.5 ± 0.03 μM) with ~30‐fold selectivity for PAR2 over PAR1 and significantly reduced the PAR2‐mediated activation of ERK1/2 and NF‐κB signaling pathway. In addition, PCG strongly decreased PAR2‐induced increases in ICAM‐1, VCAM‐1, IL‐6, IL‐8, IFN‐γ, and TNF‐α expression. Notably, in NZB/W F1 mice, which spontaneously develop severe autoimmune syndrome resembling human SLE and LN, the intraperitoneal administration of PCG significantly alleviated kidney injury and splenomegaly and reduced proteinuria and renal ICAM‐1 and VCAM‐1 expression. Our results suggest that PCG has beneficial effects on LN via inhibition of PAR2, and PCG is a potential therapeutic agent for LN.Support or Funding InformationThis research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2017R1D1A1B03029050), a faculty research grant of Yonsei University College of Medicine (6‐2016‐0159) to Sang‐Won Lee, NRF (2015R1D1A1A01057695 and 2018R1A6A1A03023718) to Wan Namkung, and NRF (2019R1I1A1A01061117) to Yohan Seo. This research was supported (in part) by the Yonsei University Research Fund (Post Doc. Researcher Supporting Program) of 2019 (project no.: 2019‐12‐0013).Schematic overview of inhibitory effect of Punicalagin (PCG) on lupus nephritis in human podocytes and NZB/W F1 mice.The inhibition of PAR2 by PCG reduced PAR2‐induced ERK1/2 and NF‐κB activation in human podocyte cell line. Notably, PCG ameliorated kidney injury, proteinuria, and splenomegaly in NZB/W F1 mice and reduced ICAM‐1 and VCAM‐1 levels via PAR2 inhibition.Figure 1

Plasmacytoid dendritic cells from parent strains of the NZB/W F1 lupus mouse contribute different characteristics to autoimmune propensity.

The NZB/W F1 (F1) mice develop severe disease that is similar to human systemic lupus erythematosus. By contrast, each parent strain, NZB or NZW, has limited autoimmunity, suggesting traits of both strains contribute to pathogenesis. Although many of the contributing genes have been identified, the contributing cellular abnormality associated with each parent strain remains unresolved. Given that plasmacytoid dendritic cells (pDCs) are key to the pathogenesis of lupus, we investigated the properties of pDCs from NZB and NZW mice. We found that NZB mouse had higher numbers of pDCs, with much of the increase being contributed by a more abundant CD8+ pDC subset. This was associated with prolonged survival and stronger proliferation of CD4+ T cells. By contrast, NZW pDCs had heightened capacity to produce interferon-α (IFNα) and IFNλ, and promoted stronger B-cell proliferation upon CpG stimulation. Thus, our data reveal the different functional and numerical characteristics of pDCs from NZW and NZB mouse.

Improved Mitochondrial Metabolism and Reduced Inflammation Following Attenuation of Murine Lupus With Coenzyme Q10 Analog Idebenone.

A role for mitochondrial dysfunction has been proposed in the immune dysregulation and organ damage characteristic of systemic lupus erythematosus (SLE). Idebenone is a coenzyme Q10 synthetic quinone analog and an antioxidant that has been used in humans to treat diverse diseases in which mitochondrial function is impaired. This study was undertaken to assess whether idebenone ameliorates lupus in murine models. Idebenone was administered orally to MRL/lpr mice at 2 different doses (1 gm/kg or 1.5 gm/kg idebenone-containing diet) for 8 weeks. At peak disease activity, clinical, immunologic, and metabolic parameters were analyzed and compared to those in untreated mice (n = 10 per treatment group). Results were confirmed in the lupus-prone NZM2328 mouse model. In MRL/lpr mice, idebenone-treated mice showed a significant reduction in mortality incidence (P < 0.01 versus untreated mice), and the treatment attenuated several disease features, including glomerular inflammation and fibrosis (each P < 0.05 versus untreated mice), and improved renal function in association with decreased renal expression of interleukin-17A (IL-17A) and mature IL-18. Levels of splenic proinflammatory cytokines and inflammasome-related genes were significantly decreased (at least P < 0.05 and some with higher significance) in mice treated with idebenone, while no obvious drug toxicity was observed. Idebenoneinhibited neutrophil extracellular trap formation in neutrophils from lupus-prone mice (P < 0.05) and human patients with SLE. Idebenone also improved mitochondrial metabolism (30% increase in basal respiration and ATP production), reduced the extent of heart lipid peroxidation (by one-half that of untreated mice), and significantly improved endothelium-dependent vasorelaxation (P < 0.001). NZM2328 mice exposed to idebenone also displayed improvements in renal and systemic inflammation, reducing the kidney pathology score (P < 0.05), IgG/C3 deposition (P < 0.05), and the gene expression of interferon, proinflammatory, and inflammasome-related genes (at least P < 0.05 and some with higher significance). Idebenone ameliorates murine lupus disease activity and the severity of organ damage, supporting the hypothesis that agents that modulate mitochondrial biologic processes may have a therapeutic role in human SLE.

SPARC Regulation of PMN Clearance Protects from Pristane Induced Lupus and Rheumatoid Arthritis

One step along the pathogenesis of Systemic lupus erythematosus (SLE) is associated with polymorphonuclear leukocyte (PMN) death and their ineffective removal by M2-macrophages. The secreted protein acidic and rich in cysteine (SPARC) is a matricellular protein with unexpected immunosuppressive function in M2-macrophages and myeloid cells. To investigate the role of SPARC in autoimmunity, we adopted a pristane–induced model of lupus in mice, which recapitulates clinical manifestations of human SLE. Sparc-/- mice developed earlier and more severe renal disease, lung and liver parenchymal damage than the WT counterpart. Most prominently, Sparc-/- mice had anticipated and severe occurrence of arthritis. An intermediate phenotype was obtained in Sparc-/- hemizygous mice, a result that suggests Sparc gene-dosage as relevant in autoimmune-related events. Mechanistically, a defective Sparc expression in PMN blocks their clearance by macrophages, through a defective delivery of eat-me and don’t eat-me signals. Sparc-/- PMN that escape macrophage scavenging becomes a source of autoantigens for dendritic cell (DC) presentation and a direct stimulus for IL-17 expression in γδ-T-cells. Gene profile analysis of synovial biopsies of knees affected by SLE-associated arthritis showed an inverse correlation between SPARC and key autoimmune genes. These results point to SPARC down-regulation as a key event characterizing SLE and associated rheumatoid arthritis pathogenesis.

Development of Murine Systemic Lupus Erythematosus in the Absence of BAFF.

To determine whether systemic lupus erythematosus (SLE) can develop in the absence of BAFF in an SLE-prone host. Starting with C57BL/6 mice that express a human BCL2 transgene (Tg) in their B cells (thereby rendering B cell survival largely independent of BAFF-triggered signals), we introgressed this Tg into NZM 2328 mice genetically deficient in BAFF (NZM.Baff-/- ) to generate NZM.Baff-/- .Bcl2Tg mice. Expression of human Bcl-2 and lymphocyte profiles were assessed by fluorescence-activated cell sorting, and serologic profiles were determined by enzyme-linked immunosorbent assay. Immunofluorescence and histologic analyses were performed to assess renal immunopathologic features in the mice, and clinical disease was assessed according to the outcomes of severe proteinuria and death. In comparison to their non-Tg NZM.Baff-/- littermates (n ≥ 7), NZM.Baff-/- .Bcl2Tg mice (n ≥ 8) overexpressed Bcl-2 in their B cells and developed significantly increased percentages and numbers of B cells and plasma cells, serum levels of IgG autoantibodies, glomerular deposition of IgG and C3, and severity of glomerular and tubulointerstitial inflammation, culminating in severe proteinuria and death (all P < 0.05 versus NZM.Baff-/- littermates). The time course for development of SLE-like features in NZM.Baff-/- .Bcl2Tg mice was more rapid than has been previously observed in NZM 2328 wild-type mice (median age at death 4.5 months versus 7.5 months). NZM.Baff-/- .Bcl2Tg mice remained responsive to BAFF, since reintroduction of the Baff gene into these mice further accelerated the course of disease (median age at death 3 months). The role of BAFF in the development of SLE-like disease may be dispensable as long as B cell survival is preserved via a BAFF-independent pathway. This may help explain the limited and variable clinical success with BAFF antagonists in human SLE. Thus, NZM.Baff-/- .Bcl2Tg mice may serve as a powerful murine model for the study of BAFF-independent SLE.

Role of Neutrophil Extracellular Traps Regarding Patients at Risk of Increased Disease Activity and Cardiovascular Comorbidity in Systemic Lupus Erythematosus.

Neutrophil extracellular traps (NET) are essential in host defense, but are also linked to inflammation and autoimmunity, including in systemic lupus erythematosus (SLE). We recently described that immune complexes (IC) induce NET formation, promoting SLE-like disease in mice. In the current study, we investigated, for the first time to our knowledge, the role of NET in human SLE and their association with disease activity and severity. Levels of NET (myeloperoxidase-DNA complexes) were analyzed in plasma from 4 cross-sectional SLE cohorts (n = 44-142), 1 longitudinal SLE cohort (n = 47), and healthy individuals (n = 100) using ELISA. Type I interferon activity was determined using a cell reporter system. Patients with SLE had elevated levels of NET in circulation compared to healthy controls (p < 0.01). NET levels identified patients with a severe disease phenotype characterized by IC-driven nephritis (p < 0.05). Though not associated with current disease activity (p = 0.20), levels of NET were associated with future increase in the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) within 3 months (OR 1.75, p = 0.01), as well as an overall heightened SLEDAI over 1 year (p < 0.01). Finally, levels of NET were associated with arterial events (OR 5.0, p = 0.02) and endothelial cell activation (p < 0.001). NET levels are elevated in patients with SLE, associated with IC-driven disease. NET levels provide significant clinical value in identifying patients at risk of active disease and/or severe disease, including nephritis and cardiovascular disease, and may allow for early interventions.

Bioengineered Immunotherapy Techniques for the Treatment of Select Secondary Immunodeficiency Disorders

The inner workings of the immune system are quite complex. Each component works diligently in order to protect us from invaders such as pathogens: viruses, microbes, and fungi. Unfortunately, the immune system may become dysfunctional, which can result in secondary immunodeficiency diseases. The treatments available for these disorders and diseases of the immune system do not typically serve to cure, and much too often the side effects associated can exacerbate the conditions. As an alternative, the area of immunotherapy seeks to remedy the limitations of today’s medicine. Through this review, insight into the current conventional treatments available for select secondary immunodeficiency diseases will be provided, particularly in Human Immunodeficiency Virus disease and Systemic Lupus Erythematosus. The modern immunotherapy approaches that are underway will then be analyzed in their capacity and potential to treat these defects of the immune system.

The IL-12-STAT4 axis in the pathogenesis of human systemic lupus erythematosus.

Generation of autoantibodies is a hallmark of systemic lupus erythematosus (SLE). As demonstrated in a number of lupus mouse models, recent evidence suggests that both GC and extrafollicular pathways contribute to the generation of autoantibodies also in human SLE, and that CD11c+ IgD- CD27- (double negative:DN) B cells play a central role in the latter pathway. In this mini-review, the author will first briefly summarize the features of CD11c+ DN B cells in human SLE, and discuss how the IL-12-STAT4 axis might contribute to the generation of autoantibodies in SLE. In addition, various types of CD4+ helper T cell subsets promoting the generation of autoantibodies in SLE will be described, and finally it will be discussed how these recent discoveries contribute to understanding of SLE pathogenesis and treatment of SLE patients.

MAP4K Family Kinases and DUSP Family Phosphatases in T-Cell Signaling and Systemic Lupus Erythematosus.

T cells play a critical role in the pathogenesis of systemic lupus erythematosus (SLE), which is a severe autoimmune disease. In the past 60 years, only one new therapeutic agent with limited efficacy has been approved for SLE treatment; therefore, the development of early diagnostic biomarkers and therapeutic targets for SLE is desirable. Mitogen-activated protein kinase kinase kinase kinases (MAP4Ks) and dual-specificity phosphatases (DUSPs) are regulators of MAP kinases. Several MAP4Ks and DUSPs are involved in T-cell signaling and autoimmune responses. HPK1 (MAP4K1), DUSP22 (JKAP), and DUSP14 are negative regulators of T-cell activation. Consistently, HPK1 and DUSP22 are downregulated in the T cells of human SLE patients. In contrast, MAP4K3 (GLK) is a positive regulator of T-cell signaling and T-cell-mediated immune responses. MAP4K3 overexpression-induced RORγt–AhR complex specifically controls interleukin 17A (IL-17A) production in T cells, leading to autoimmune responses. Consistently, MAP4K3 and the RORγt–AhR complex are overexpressed in the T cells of human SLE patients, as are DUSP4 and DUSP23. In addition, DUSPs are also involved in either human autoimmune diseases (DUSP2, DUSP7, DUSP10, and DUSP12) or T-cell activation (DUSP1, DUSP5, and DUSP14). In this review, we summarize the MAP4Ks and DUSPs that are potential biomarkers and/or therapeutic targets for SLE.

Lupus Autoimmunity and Metabolic Parameters Are Exacerbated Upon High Fat Diet-Induced Obesity Due to TLR7 Signaling.

Systemic lupus erythematosus (SLE) patients have increased prevalence of metabolic syndrome but the underlying mechanisms are unknown. Toll-like receptor 7 (TLR7) that detects single stranded-RNA plays a key role in antimicrobial host defense and also contributes to the initiation and progression of SLE both in mice and humans. Here, we report the implication of TLR7 signaling in high fat diet (HFD)-induced metabolic syndrome and exacerbation of lupus autoimmunity in TLR8-deficient (TLR8ko) mice, which develop spontaneous lupus-like disease due to increased TLR7 signaling by dendritic cells (DCs). The aggravated SLE pathogenesis in HFD-fed TLR8ko mice was characterized by increased overall immune activation, anti-DNA autoantibody production, and IgG/IgM glomerular deposition that were coupled with increased kidney histopathology. Moreover, upon HFD TLR8ko mice developed metabolic abnormalities, including liver inflammation. In contrast, upon HFD TLR7/8ko mice did not develop SLE and both TLR7ko and TLR7/8ko mice were fully protected from metabolic abnormalities, including body weight gain, insulin resistance, and liver inflammation. Interestingly, HFD led to an increase of TLR7 expression in WT mice, that was coupled with increased TNF production by DCs, and this phenotype was more profound in TLR8ko mice. Our study uncovers the implication of TLR7 signaling in the interconnection of SLE and metabolic abnormalities, indicating that TLR7 might be a novel approach as a tailored therapy in SLE and metabolic diseases.

AhR-ROR-γt complex is a therapeutic target for MAP4K3/GLKhighIL-17Ahigh subpopulation of systemic lupus erythematosus.

The cytokine IL-17A plays critical roles in the pathogenesis of autoimmune diseases. The frequencies of MAP kinase kinase kinase kinase 3 [also named germinal center kinase–like kinase (GLK)]-overexpressing T cells are correlated with disease severity of systemic lupus erythematosus (SLE). T-cell–specific GLK-transgenic mice develop spontaneous autoimmune responses through IL-17A. GLK signaling selectively stimulates IL-17A production in murine T cells through inducing aryl hydrocarbon receptor (AhR)–retinoic acid receptor–related orphan nuclear receptor-γt (ROR-γt) complex formation. Here, we investigated whether GLK-induced AhR–ROR-γt complex in T cells is a therapeutic target for human SLE. The population of GLK+IL-17A+ T cells was enhanced in the peripheral blood from patients with SLE compared with that of healthy controls using flow cytometry. The receiver operating characteristic curve analysis showed that increased GLK+IL-17A+ T-cell population in peripheral blood reflected an active stage of SLE. In addition, peripheral blood T cells from patients with SLE displayed induction of ROR-γt phosphorylation and the AhR–ROR-γt (and AhR–phosphorylated ROR-γt) complex. Moreover, we identified a small-molecule inhibitor, verteporfin, that inhibited GLK kinase activity and AhR–ROR-γt interaction. The small-molecule inhibitor verteporfin suppressed the disease severity in autoimmune mouse models and IL-17A production in T cells from patients with SLE. Collectively, the GLK-induced AhR–ROR-γt (and AhR–phosphorylated ROR-γt) complex is a therapeutic target for the GLKhighIL-17Ahigh subpopulation of human patients with SLE.—Chuang, H.-C., Chen, Y.-M., Chen, M.-H., Hung, W.-T., Yang, H.-Y., Tseng, Y.-H., Tan, T.-H. AhR–ROR-γt complex is a therapeutic target for MAP4K3/GLKhighIL-17Ahigh subpopulation of systemic lupus erythematosus.

CD4+CD69+ T cells and CD4+CD25+FoxP3+ Treg cells imbalance in peripheral blood, spleen and peritoneal lavage from pristane-induced systemic lupus erythematosus (SLE) mice

BackgroundAdaptive immune cells, including CD4+CD69+ and CD4+CD25+FoxP3+ regulatory T (Treg) cells, are important for maintaining immunological tolerance. In human systemic lupus erythematosus (SLE), CD4+CD25+FoxP3+ Treg cells are reduced, whereas CD69 expression is increased, resulting in a homeostatic immune imbalance that may intensify autoreactive T cell activity. To analyze the mechanisms implicated in autotolerance failure, we evaluated CD4+CD69+ and CD4+CD25+FoxP3+ T cells and interleukin profiles in a pristane-induced SLE experimental model.MethodsFor lupus induction, 26 female Balb/c mice received a single intraperitoneal 0.5 ml dose of pristane, and 16 mice received the same dose of saline. Blood and spleen samples were collected from euthanized mice 90 and 120 days after pristane or saline inoculation. Mononuclear cells from peripheral blood (PBMC), peritoneal lavage (PL) and splenocytes were obtained by erythrocyte lysis and cryopreserved for further evaluation by flow cytometry using the GuavaEasyCyte TM HT. After thawing, cells were washed and stained with monoclonal antibodies against CD3, CD4, CD8, CD25, CD28, CD69, FoxP3, CD14 and Ly6C (BD Pharmingen TM). Interleukins were quantified using Multiplex® MAP. The Mann-Whitney test and the Pearson coefficient were used for statistical analysis, and p < 0.05 considered significant.ResultsCompared with the controls, SLE-induced animals presented increased numbers of CD4+CD69+ T cells in the blood on T90 and T120 (p = 0.022 and p = 0.008) and in the spleen on T120 (p = 0.049), but there were decreased numbers in the PL (p = 0.049) on T120. The percentage of Treg was lower in blood (p < 0.005 and p < 0.012) on T90 and T120, in spleen (p = 0.043) on T120 and in PL (p = 0.001) on T90. Increased numbers of CD4 + CD69+ T cells in the PL were positively associated with high IL-2 (p = 0.486) and IFN-γ (p = 0.017) levels, whereas reduced Treg cells in the blood were negatively correlated with TNFα levels (p = 0.043) and positively correlated with TGFβ1 (p = 0.038).ConclusionIncreased numbers of CD4+CD69+ T cells and reduced numbers of CD4+CD25+FoxP3+ Treg cells with an altered interleukin profile suggests loss of autotolerance in pristane-induced lupus mice, which is similar to human lupus. Therefore, this model is useful in evaluating mechanisms of cellular activation, peripheral tolerance and homeostatic immune imbalance involved in human SLE.

Metformin Inhibits the Type 1 IFN Response in Human CD4+ T Cells.

In systemic lupus erythematosus, defective clearance of apoptotic debris and activation of innate cells result in a chronically activated type 1 IFN response, which can be measured in PBMCs of most patients. Metformin, a widely used prescription drug for Type 2 diabetes, has a therapeutic effect in several mouse models of lupus through mechanisms involving inhibition of oxidative phosphorylation and a decrease in CD4+ T cell activation. In this study, we report that in CD4+ T cells from human healthy controls and human systemic lupus erythematosus patients, metformin inhibits the transcription of IFN-stimulated genes (ISGs) after IFN-α treatment. Accordingly, metformin inhibited the phosphorylation of pSTAT1 (Y701) and its binding to IFN-stimulated response elements that control ISG expression. These effects were independent of AMPK activation or mTORC1 inhibition but were replicated using inhibitors of the electron transport chain respiratory complexes I, III, and IV. This indicates that mitochondrial respiration is required for ISG expression in CD4+ T cells and provides a novel mechanism by which metformin may exert a therapeutic effect in autoimmune diseases.

Epigenetic programming underpins B cell dysfunction in human SLE.

Systemic lupus erythematosus (SLE) is characterized by the expansion of extrafollicular pathogenic B cells derived from newly activated naïve cells. Although these cells express distinct markers, their epigenetic architecture and how it contributes to SLE remains poorly understood. To address this, we determined the DNA methylomes, chromatin accessibility and transcriptomes from five human B cell subsets, including a newly defined effector B cell subset from SLE and healthy subjects. Our data define a differentiation hierarchy between the subsets and elucidate the epigenetic and transcriptional differences between effector and memory B cells. Importantly, an SLE molecular signature was already established in resting naïve cells and was dominated by accessible chromatin enriched in AP-1 and EGR transcription factor motifs. Together, these factors acted in synergy with T-BET to shape the epigenome of expanded SLE effector B cell subsets. Thus, our data define the molecular foundation of pathogenic B cell dysfunction in SLE.

RP220, a Renalase Peptide, Attenuates Lupus Nephritis by Anti-Inflammatory in MRL/lpr Mice

Background: Lupus nephritis (LN) is a common and serious complication of systemic lupus erythematosus (SLE), which inflammation plays an important role in the progression of the disease. RP220, an active peptide of renalase, was proved previously to be effective in protecting kidney against ischemic and toxic injury by anti-inflammatory effect. We aimed to investigate the therapeutic effect of RP220 in lupus nephritis and its possible mechanism. Methods: MRL/lpr mice were treated by RP220, cyclophosphamide (CP) and saline respectively. Urine albumin creatinine ratio, serum creatinine and blood urea nitrogen, circulating autoantibody levels and renal histopathological assessment was done to evaluate the renal damage and immunology status for all the mice. Renal pro-inflammatory cytokines including IL-1β, IL-6, CCL-2, TNF-α and NLRP3 inflammasome were assessed by real-time PCR and western blotting. Mouse macrophage cell line (RAW264.7) were treated by renalase-siRNA and RP220 to verify its antiinflammatory effects in vitro. Results: Urinary albumin creatinine ratio, blood urea nitrogen (BUN) and serum anti-dsDNA antibody were significantly lower in RP220 and CP group compared with saline group at the end of the experiment. Renal immune complex deposition and the injury score of glomerular, tubular and perivascular were significantly lower in RP220 and CP treated group as well as inflammatory cytokines such as TNF-α, IL-6 and IL-1β and NLRP3. The increase of renal expression of NLRP3, ASC and caspase-1 was reversed by RP220 but not by CP. Moreover, RP220 treated mice has no significant adverse effect such as body weight loss, bone marrow arrest and immune over inhibition in CP group. In vitro study of macrophage cell found that the expression of TNF-α, IL-6, IL-1β and CCL-2 induced by LPS were significantly aggravated by RP220 targeted siRNA and the effects were reversed by RP220 administration. Conclusion: Administration of RP220 ameliorated proteinuria, renal injury and inflammatory status in LN murine model without adverse effects. The renal protective effect of RP220 might be associated with NLRP3-IL1 β pathway. Development of pharmacologic peptide would be helpful in providing novel therapeutic strategies for human SLE. Funding Statement: This work was supported by the National Science and Technology Major Project (No. 81770666), Shanghai Municipal Health Commission Project (ZY(2018-2020)-FWTX-1001, 20154Y0003) and research funding to LING WANG from Shanghai Shenkang Hospital Development Center(16CR3022A). Declaration of Interests: The authors declare no conflict of interest. Ethics Approval Statement: All experiments were approved by the Institutional Animal Care Committee of Shanghai Jiaotong University.

High TLR7 Expression Drives the Expansion of CD19+CD24hiCD38hi Transitional B Cells and Autoantibody Production in SLE Patients.

Signaling through Toll-like receptor 7 (TLR7) drives the production of type I IFN and promotes the activation of autoreactive B cells and is implicated in the pathogenesis of systemic lupus erythematosus (SLE). While TLR7 has been extensively studied in murine lupus, much less is known about its role in the pathogenesis of human SLE. Genetic studies support a link between the TLR7 rs3853839 C/G polymorphism, which affects TLR7 mRNA turnover, and SLE susceptibility; however, the effects of this polymorphism on B cells have not been studied. Here we determined how changes in TLR7 expression affect peripheral B cells and auto-Ab production in SLE patients. High TLR7 expression in SLE patients driven by TLR7 rs3853839 C/G polymorphism was associated with more active disease and upregulation of IFN-responsive genes. TLR7hi SLE patients showed an increase in peripheral B cells. Most notably, the percentage and numbers of CD19+CD24++CD38++ newly-formed transitional (TR) B cells were increased in TLR7hi SLE patients as compared to HCs and TLR7norm/lo SLE patients. Using auto-Ab arrays, we found an increase and enrichment of auto-Ab specificities in the TLR7hi SLE group, including the production of anti-RNA/RNP-Abs. Upon in vitro TLR7 ligand stimulation, TR B cells isolated from TLR7hi but not TLR7norm/lo SLE patients produced anti-nuclear auto-Abs (ANA). Exposure of TR B cells isolated from cord blood to IFNα induced the expression of TLR7 and enabled their activation in response to TLR7 ligation in vitro. Our study shows that overexpression of TLR7 in SLE patients drives the expansion of TR B cells. High TLR7 signaling in TR B cells promotes auto-Ab production, supporting a possible pathogenic role of TR B cells in human SLE.

Dendritic cell-associated B7-H3 suppresses the production of autoantibodies and renal inflammation in a mouse model of systemic lupus erythematosus

B7-H3 immune modulatory molecule has been implicated in the generation and pathogenesis of autoimmune diseases, the mechanism of action is less known. We explored the role of B7-H3 in the induction of autoantibodies and organ-directed inflammation in a murine systemic lupus erythematosus (SLE) model in which the immunization with DNA extracted from activated T cells induced the production of anti-DNA autoantibodies and subsequent glomerulonephritis, two hallmarks of human SLE. Mice deficient of B7-H3 or treated with a B7-H3 specific antibody produced significantly higher levels of anti-DNA autoantibodies and more severe glomerulonephritis than wild-type mice, indicating an inhibitory function of B7-H3 in this model. Interestingly, immunization of mice with DNA-pulsed dendritic cells induced severe SLE symptoms while B7-H3 on dendritic cells is required in this process. Importantly, treatment of mice with recombinant B7-H3Ig fusion protein effectively ameliorated progression of murine SLE, accompanied with decreased level of anti-DNA autoantibodies and alleviated glomerulonephritis, decreased autoantibody deposition and complement deposition in kidney. Our findings implicate a potential role of B7-H3 on dendritic cells in the induction of SLE and as a potential target for the treatment of autoimmune diseases.

Autoantibodies in Systemic Lupus Erythematosus Target Mitochondrial RNA.

The mitochondrion supplies energy to the cell and regulates apoptosis. Unlike other mammalian organelles, mitochondria are formed by binary fission and cannot be directly produced by the cell. They contain numerous copies of a compact circular genome that encodes RNA molecules and proteins involved in mitochondrial oxidative phosphorylation. Whereas, mitochondrial DNA (mtDNA) activates the innate immune system if present in the cytosol or the extracellular milieu, it is also the target of circulating autoantibodies in systemic lupus erythematosus (SLE). However, it is not known whether mitochondrial RNA is also recognized by autoantibodies in SLE. In the present study, we evaluated the presence of autoantibodies targeting mitochondrial RNA (AmtRNA) in SLE. We quantified AmtRNA in an inducible model of murine SLE. The AmtRNA were also determined in SLE patients and healthy volunteers. AmtRNA titers were measured in both our induced model of murine SLE and in human SLE, and biostatistical analyses were performed to determine whether the presence and/or levels of AmtRNA were associated with clinical features expressed by SLE patients. Both IgG and IgM classes of AmtRNA were increased in SLE patients (n = 86) compared to healthy controls (n = 30) (p < 0.0001 and p = 0.0493, respectively). AmtRNA IgG levels correlated with anti-mtDNA-IgG titers (rs = 0.54, p < 0.0001) as well as with both IgG and IgM against β-2-glycoprotein I (anti-β2GPI; rs = 0.22, p = 0.05), and AmtRNA-IgG antibodies were present at higher levels when patients were positive for autoantibodies to double-stranded-genomic DNA (p < 0.0001). AmtRNA-IgG were able to specifically discriminate SLE patients from healthy controls, and were negatively associated with plaque formation (p = 0.04) and lupus nephritis (p = 0.03). Conversely, AmtRNA-IgM titers correlated with those of anti-β2GPI-IgM (rs = 0.48, p < 0.0001). AmtRNA-IgM were higher when patients were positive for anticardiolipin antibodies (aCL-IgG: p = 0.01; aCL-IgM: p = 0.002), but AmtRNA-IgM were not associated with any of the clinical manifestations assessed. These findings identify mtRNA as a novel mitochondrial antigen target in SLE, and support the concept that mitochondria may provide an important source of circulating autoantigens in SLE.

Validation of lanthionine synthetase C-like 2 (LANCL2) as a therapeutic target for systemic lupus erythematosus

Abstract Lanthionine synthetase C-like 2 (LANCL2) is a membrane receptor with downstream effects on immunity and metabolism including the differentiation of regulatory CD4+ T cells. Its natural ligand, abscisic acid (ABA), has been shown to be decreased in autoimmune and inflammatory disease. Given the implication of the LANCL2 pathway in autoimmune disease and the progression of LANCL2-specific ligands, such as BT-11, into clinical stage development, we assessed the role of LANCL2 in systemic lupus erythematosus (SLE). In a TLR7/8 resiquimod-induced model of SLE, the loss of LANCL2 significantly decreases survival (P = 0.0008) relative to wild-type, resulting in less than 10% survival and a greater than 60% reduction relative to wild-type. Similarly, LANCL2−/− displayed greater serum anti-dsDNA antibodies and higher proteinuria. Within spleens, the loss of LANCL2 resulted in greater IL-6 and TNF, higher proportions of T follicular helper cells and lower ratios of regulatory CD4+ T cells relative to IFNγ producing cells. The greater inflammation was also mirrored in transcriptional changes at the splenic level indicating a greater susceptibility to severe disease. These results merit further exploration into the implication of LANCL2 signaling in human SLE and characterization of the therapeutic efficacy of LANCL2-specific agonists for future SLE development. Thus, LANCL2 is a novel promising therapeutic target for SLE.