Human Systemic Lupus Erythematosus Research Articles

Sex-specific differences in SLE – Significance in the experimental setting of inflammation and kidney damage in MRL-Faslpr mice

Animal models are an important tool in the research of chronic autoimmune diseases, like systemic lupus erythematosus (SLE). MRL-Faslpr mice are one of different lupus models that develop spontaneously an SLE-like disease with autoantibodies and immune complex deposition that leads into damage of different organs. In contrast to human SLE, both sexes of MRL-Faslpr mice develop a similar autoimmune disease. Due to the sex bias in human and the delayed disease progression in male MRL-Faslpr mice, the majority of studies have been performed in female mice. To determine the suitability of male MRL-Faslpr mice for SLE research, especially with regard to the 3 R-principle and animal welfare, analyses of phenotype, inflammation and damage with focus on kidney and spleen were performed in mice of both sexes. Female mice developed lymphadenopathy and skin lesions earlier as males. At an age of 3.5 month, more immune cells infiltrated kidney and spleen in females compared to males. At the age of 5 months, however, substantially less sex-specific differences were detected. Since other studies have shown differences between both sexes on other manifestations like autoimmune pancreatitis and Sjögren syndrome in MRL-Faslpr mice, the use of male mice as part of 3 R-principle and animal welfare must be carefully considered.

#971 Effects of arsenic trioxide on MMP9/IL-17A expression in lupus nephritis—results from bioinformatics analysis and in vitro studies

Abstract Background and Aims Previous research has indicated that ATO treatment at low doses may decrease the likelihood of flares in active systemic lupus erythematosus (SLE) patients, but the pharmacological mechanisms of such effect have not been studied. Method Machine learning and network pharmacology analysis were employed to explore the potential targets from differentially expressed genes (DEGs) of human SLE and LN peripheral blood mononuclear cells (PBMCs) microarray datasets and pharmacological databases. GO and KEGG analyses were performed, and the protein-protein interaction (PPI) network was constructed. The association of these characteristic genes and immune cells were further examined and validated. Results Three machine learning models (RF, SVM, and XGB) were utilized to identify five immunoregulatory genes in SLE among twelve intersection DEGs. Among these genes, MMP9 exhibited the highest ROC AUC (0.92) in predicting disease development. KEGG analysis revealed significant associations with the IL-17 signaling pathway (p = 1.67E-18). Furthermore, ssGSEA analysis indicated positive correlations between MMP9 and macrophages (correlation coefficient 0.88) as well as neutrophils (correlation coefficient 0.66). In vitro treatment of PBMCs from lupus nephritis (LN) patients with ATO resulted in downregulation of MMP9 and IL-17A, validating our bioinformatics findings. Conclusion ATO has the potential to mitigate the MMP/IL-17A pathways in PBMCs in LN patients, and hence maybe a promising and innovative therapeutic alternative.

A Novel Human Interleukin-23A Overexpressing Mouse Model of Systemic Lupus Erythematosus.

Interleukin-23 (IL-23) is a crucial cytokine implicated in chronic inflammation and autoimmunity, associated with various diseases such as psoriasis, psoriatic arthritis, and systemic lupus erythematosus (SLE). This study aimed to create and characterize a transgenic mouse model overexpressing human IL-23A (TghIL-23A), providing a valuable tool for investigating the pathogenic role of human IL-23A and evaluating the efficacy of anti-human IL-23A therapeutics. TghIL-23A mice were generated via microinjection of CBA × C57BL/6 zygotes with a fragment of the human IL23A gene, flanked by its 5'-regulatory sequences and the 3' untranslated region of human β-globin. The TghIL-23A pathology was assessed through hematologic and biochemic analyses, cytokine and antinuclear antibody detection, and histopathologic examination of skin and renal tissues. The response to the anti-human IL-23A therapeutic agent guselkumab was evaluated in groups of eight mixed-sex mice receiving subcutaneous treatment twice weekly for 10 weeks using clinical, biomarker, and histopathologic readouts. TghIL-23A mice exhibited interactions between human IL-23A and mouse IL-23/IL-12p40 and developed a chronic multiorgan autoimmune disease marked by proteinuria, anti-double-stranded DNA antibodies, severe inflammatory lesions in the skin, and milder phenotypes in the kidneys and lungs. The TghIL-23A pathologic features exhibited significant similarities to those observed in human patients with SLE, and they were reversed following guselkumab treatment. We have generated and characterized a novel genetic mouse model of SLE, providing proof-of-concept for the etiopathogenic role of human IL-23A. This new model has a normal life span and integrates several characteristics of the human disease's complexity and chronicity, making it an attractive preclinical tool for studying IL-23-dependent pathogenic mechanisms and assessing the efficacy of anti-human IL-23A or modeled disease-related therapeutics.

Serum isolevuglandin IgG antibody concentrations are increased in patients with systemic lupus erythematosus and associated with lower 24-hour blood pressure

ObjectiveHypertension is frequent in patients with systemic lupus erythematosus (SLE) and is a major contributor to increased cardiovascular risk. Isolevuglandins (IsoLGs) are downstream products of oxidative stress that drive hypertension and SLE disease activity in animal models. Antibodies to IsoLGs (anti-IsoLGs) are present in human SLE and associated with disease activity, but it is not known if concentrations are higher compared to control subjects or if they are associated with blood pressure (BP).MethodsWe measured serum anti-IsoLG IgG antibody concentrations by sandwich ELISA in 23 patients with SLE and 30 controls who had participated in a cross-sectional 24-hour ambulatory BP study. We examined the association between anti-IsoLG IgG antibodies and BP measurements in patients with SLE and controls by Spearman Rho (rs) and linear regression analysis.ResultsSerum anti-IsoLG IgG antibody concentrations were higher in patients with SLE than controls (P = 0.007) and inversely associated with BP in SLE but not controls. In patients with SLE antibody concentrations were inversely associated with office (rs = −0.418) and diurnal systolic BP (rs = −0.421); the relationship was stronger among patients not taking anti-hypertensives (office: rs = −0.740, diurnal systolic BP: rs = −0.802) and every 20% increase in antibody concentration was associated with 10 mmHg decrease in 24-hour systolic BP (P = 0.004).ConclusionSerum anti-IsoLG IgG antibody concentrations are higher in patients with SLE than controls and are inversely associated with 24-hour BP measurements. Since IsoLGs promote hypertension, it is possible that in SLE, IsoLG antibodies could help clear these hypertension-inducing antigens.

Comprehensive Pan-cancer Analysis of CMPK2 as Biomarker and Prognostic Indicator for Immunotherapy.

UMP-CMP kinase 2 (CMPK2) is involved in mitochondrial DNA synthesis which can be oxidized and released into the cytoplasm in innate immunity. It initiates the assembly of NLRP3 inflammasomes and mediates various pathological processes such as human immunodeficiency virus infection and systemic lupus erythematosus. However the role of CMPK2 in tumor progression and tumor immunity remains unclear. In this study we conducted a systematical analysis of CMPK2 across 33 different cancers based on datasets such as Genotype Tissue-Expression (GTEx) The Cancer Genome Atlas (TCGA) the Cancer Cell Line Encyclopedia (CCLE) and Tumor Immune Syngeneic Mouse (TISMO). Our focus encompassed the characterization of CMPK2 expression patternsclinical significance potential regulatory mechanisms and its relationship with the tumor immune profile including responsiveness to immune checkpoint inhibitor treatment. CMPK2 expression was elevated in 23 cancers and decreased in two cancers. Receiver operating characteristic curve analysis indicated that CMPK2 expression had a high diagnostic value for 16 cancers. Kaplan-Meier survival analysis showed that high CMPK2 expression was associated with Lower Overall Survival (OS)Disease- Specific Survival (DSS) and Progression-Free Interval (PFI) in Kidney Cutaneous Chromophobe (KICH) Uterine Corpus Endometrial Carcinoma (UCEC) and Uveal Melanoma (UVM) and the opposite was true in Skin Cutaneous Melanoma (SKCM). Immune microenvironment-related analysis revealed strong associations between CMPK2 expression and immune cell infiltration as well as immune checkpoint expression across various tumors. Notably in four mouse immunotherapy cohorts CMPK2 expression in treated mouse tumors was post-treatment. In five clinical immunotherapy cohorts patients with high CMPK2 expression show better responses to immunotherapy. Furthermore the methylation level of the CMPK2 gene was closely correlated to its expression and tumor prognosis. Among these cancers the clinical and immunological indications of SKCM are particularly closely related to CMPK2 expression. Our analysis preliminarily describes the complex function of CMPK2 in cancer progression and immune microenvironment highlighting its potential as a diagnostic and therapeutic target for immunotherapy.

Double-Negative T (DNT) Cells in Patients with Systemic Lupus Erythematosus.

Double-negative T (DNT) cells are a rare and unconventional T-lymphocyte subpopulation lacking both CD4 and CD8 markers. Their immunopathological roles and clinical relevance have yet to be elucidated. Beyond autoimmune lymphoproliferative syndrome (ALPS), these cells may also play a role in rheumatic disorders, including systemic lupus erythematosus (SLE); indeed, these two diseases share several autoimmune manifestations (including nephritis). Moreover, one of the main experimental murine models used to investigate lupus, namely the MRL/lpr mouse, is characterized by an expansion of DNT cells, which can support the production of pathogenic autoantibodies and/or modulate the immune response in this context. However, lupus murine models are not completely consistent with their human SLE counterpart, of course. In this mini review, we summarize and analyze the most relevant clinical studies investigating the DNT cell population in SLE patients. Overall, based on the present literature review and analysis, DNT cell homeostasis seems to be altered in patients with SLE. Indeed, most of the available clinical studies (which include both adults and children) reported an increased DNT cell percentage in SLE patients, especially during the active phases, even though no clear correlation with disease activity and/or inflammatory parameters has been clearly established. Well-designed, standardized, and longitudinal clinical studies focused on DNT cell population are needed, in order to further elucidate the actual contribution of these cells in SLE pathogenesis and their interactions with other immune cells (also implicated and/or altered in SLE, such as basophils), and clarify whether their expansion and/or immunophenotypic aspects may have any immunopathological relevance (and, then, represent potential disease markers and, in perspective, even therapeutic targets) or are just an unspecific epiphenomenon of autoimmunity.

Naturally occurring autoimmune disease in (NZB X NZW) F1 mice is correlated with suppression of MZ B cell development due to aberrant B Cell Receptor (BCR) signaling, which is exacerbated by exposure to inorganic mercury.

Autoimmune diseases are multifactorial and include environmental as well as genetic drivers. Although much progress has been made in understanding the nature of genetic underpinnings of autoimmune disease, by comparison much less is understood regarding how environmental factors interact with genetics in the development of autoimmunity and autoimmune disease. In this report, we utilize the (NZB X NZW) F1 mouse model of Systemic Lupus Erythematosus (SLE). Mercury is a xenobiotic that is environmentally ubiquitous and is epidemiologically linked with the development of autoimmunity. Among other attributes of human SLE, (NZB X NZW) F1 mice spontaneously develop autoimmune-mediated kidney disease. It has been previously shown that if (NZB X NZW) F1 mice are exposed to inorganic mercury (Hg2+), the development of autoimmunity, including autoimmune kidney pathology, is accelerated. We now show that in these mice the development of kidney disease is correlated with a decreased percentage of marginal zone (MZ) B cells in the spleen. In Hg2+-intoxicated mice, kidney disease is significantly augmented, and matched by a greater decrease in MZ B cell splenic percentages than found in control mice. In Hg2+- intoxicated mice, the decrease in MZ B cells appears to be linked to aberrant B Cell Receptor (BCR) signal strength in transitory 2 (T2) B cells, developmental precursors of MZ B cells.

Novel biomarker discovery through comprehensive proteomic analysis of lupus mouse serum

ObjectivesThe difficulty of monitoring organ-specific pathology in systemic lupus erythematosus (SLE) often complicates disease prognostication and treatment. Improved non-invasive biomarkers of active organ pathology, particularly lupus nephritis, would improve patient care. We sought to validate and apply a novel strategy to generate the first comprehensive serum proteome of a lupus mouse model and identify mechanism-linked lupus biomarker candidates for subsequent clinical investigation. MethodsSerum levels of 1308 diverse proteins were measured in eight adult female MRL/lpr lupus mice and eight control MRL/mpj mice. ELISA validation confirmed fold increases. Protein enrichment analysis provided biological relevance to findings. Individual protein levels were correlated with measures of lymphoproliferative, humoral, and renal disease. ResultsFour hundred and six proteins were increased in MRL/lpr serum, including proteins increased in human SLE such as VCAM-1, L-selectin, TNFRI/II, TWEAK, CXCL13, MCP-1, IP-10, IL-10, and TARC. Newly validated proteins included IL-6, IL-17, and MDC. Results of pathway enrichment analysis, which revealed enhancement of cytokine signaling and immune cell migration, reinforced the similarity of the MRL/lpr disease to human pathology. Fifty-two proteins positively correlated with at least one measure of lupus-like disease. TECK, TSLP, PDGFR-alpha, and MDC were identified as novel candidate biomarkers of renal disease. ConclusionsWe successfully validated a novel serum proteomic screening strategy in a spontaneous murine lupus model that highlighted potential new biomarkers. Importantly, we generated a comprehensive snapshot of the serum proteome which will enable identification of other candidates and serve as a reference for future mechanistic and therapeutic studies in lupus.

Cutting Edge: TLR2 Signaling in B Cells Promotes Autoreactivity to DNA via IL-6 Secretion.

Autoantibodies to chromatin and dsDNA are a hallmark of systemic lupus erythematosus (SLE). In a mouse model of monogenic human SLE caused by DNASE1L3 deficiency, the anti-DNA response is dependent on endosomal nucleic acid-sensing TLRs TLR7 and TLR9. In this study, we report that this response also required TLR2, a surface receptor for microbial products that is primarily expressed on myeloid cells. Cell transfers into lymphopenic DNASE1L3-deficient mice showed that TLR2 was required for anti-DNA Ab production by lymphocytes. TLR2 was detectably expressed on B cells and facilitated the production of IL-6 by B cells activated in the presence of microbial products. Accordingly, treatment with broad-spectrum antibiotics or Ab-mediated blockade of IL-6 delayed the anti-DNA response in DNASE1L3-deficient mice. These studies reveal an unexpected B cell-intrinsic role of TLR2 in systemic autoreactivity to DNA, and they suggest that microbial products may synergize with self-DNA in the activation of autoreactive B cells in SLE.

B cell-intrinsic TLR7 expression drives severe lupus in TLR9-deficient mice.

The endosomal Toll-like receptor 7 (TLR7) is a major driver of murine and human systemic lupus erythematosus (SLE). The role of TLR7 in lupus pathogenesis is enhanced when the regulatory role of TLR9 is absent. TLR7 signaling in plasmacytoid DCs (pDC) is generally thought to be a major driver of the IFN response and disease pathology; however, the cell types in which TLR7 acts to mediate disease have not been distinguished. To address this, we selectively deleted TLR7 in either CD11c+ cells or CD19+ cells; using a TLR7-floxed allele, we created on the lupus-prone MRL/lpr background, along with a BM chimera strategy. Unexpectedly, TLR7 deficiency in CD11c+ cells had no impact on disease, while TLR7 deficiency in CD19+ B cells yielded mild suppression of proteinuria and a trend toward reduced glomerular disease. However, in TLR9-deficient MRL/lpr mice with accelerated SLE, B cell-specific TLR7 deficiency greatly improved disease. These results support revision of the mechanism by which TLR7 drives lupus and highlight a cis regulatory interaction between the protective TLR9 and the pathogenic TLR7 within the B cell compartment. They suggest B cell-directed, dual TLR7 antagonism/TLR9 agonism or dual TLR7/9 antagonism as a potential future therapeutic strategy to treat SLE.

Impact of GADD45A on Radiation Biodosimetry Using Mouse Peripheral Blood.

High-dose-radiation exposure in a short period of time leads to radiation syndromes characterized by severe acute and delayed organ-specific injury accompanied by elevated organismal morbidity and mortality. Radiation biodosimetry based on gene expression analysis of peripheral blood is a valuable tool to detect exposure to radiation after a radiological/nuclear incident and obtain useful biological information that could predict tissue and organismal injury. However, confounding factors, including chronic inflammation, can potentially obscure the predictive power of the method. GADD45A (Growth arrest and DNA damage-inducible gene a) plays important roles in cell growth control, differentiation, DNA repair, and apoptosis. GADD45A-deficient mice develop an autoimmune disease, similar to human systemic lupus erythematosus, characterized by severe hematological disorders, kidney disease, and premature death. The goal of this study was to elucidate how pre-existing inflammation in mice, induced by GADD45A ablation, can affect radiation biodosimetry. We exposed wild-type and GADD45A knockout male C57BL/6J mice to 7 Gy of X rays and 24 h later RNA was isolated from whole blood and subjected to whole genome microarray and gene ontology analyses. Dose reconstruction analysis using a gene signature trained on gene expression data from irradiated wild-type male mice showed accurate reconstruction of either a 0 Gy or 7 Gy dose with root mean square error of ± 1.05 Gy (R^2 = 1.00) in GADD45A knockout mice. Gene ontology analysis revealed that irradiation of both wild-type and GADD45A-null mice led to a significant overrepresentation of pathways associated with morbidity and mortality, as well as organismal cell death. However, based on their z-score, these pathways were predicted to be more significantly overrepresented in GADD45A-null mice, implying that GADD45A deletion may exacerbate the deleterious effects of radiation on blood cells. Numerous immune cell functions and quantities were predicted to be underrepresented in both genotypes; however, differentially expressed genes from irradiated GADD45A knockout mice predicted an increased deterioration in the numbers of T lymphocytes, as well as myeloid cells, compared with wild-type mice. Furthermore, an overrepresentation of genes associated with radiation-induced hematological malignancies was associated with GADD45A knockout mice, whereas hematopoietic and progenitor cell functions were predicted to be downregulated in irradiated GADD45A knockout mice. In conclusion, despite the significant differences in gene expression between wild-type and GADD45A knockout mice, it is still feasible to identify a panel of genes that could accurately distinguish between irradiated and control mice, irrespective of pre-existing inflammation status.

#3839 THERAPEUTIC TARGETS OF ARSENIC TRIOXIDE IN LUPUS NEPHRITIS – DATA FROM BIOINFORMATICS ANALYSIS AND IN VITRO STUDIES

Abstract Background and Aims Patients with systemic lupus erythematosus (SLE) are at an increased risk of developing lupus nephritis (LN), which results in high morbidity and mortality. There is preliminary data showing the efficacy of low dose of Arsenic Trioxide (ATO) in reducing renal flares amongst LN patients, but the underlying mechanism for such benefit remains unclear. Method We performed bioinformatic analysis and network pharmacology to elucidate the potential targets from differentially expressed genes (DEGs) of human SLE and LN peripheral blood mononuclear cells (PBMCs) datasets and pharmacological databases. The relationship between the potential targets and immune cells was further analyzed. Results Twelve intersection genes of DEGs in SLE, predicting targets of ATO and immune related genes were identified. KEGG pathway analysis suggested that the mechanisms of ATO in SLE were associated with IL-17 signalling pathway (p = 1.67E-18), TNF signalling pathway (p = 5.77E-11) and NOD-like receptor signalling pathway (p = 1.93E-09). Ten types of immune cells showed significant difference with intersection genes expression in SLE using ssGSEA approach. MMP9 was the most significantly associated with immune cells and showed positive correlations with macrophages and neutrophils. A significant TF-MMP9-miRNA regulatory network was constructed using cytoscape software. Pilot data from our in vitro studies suggested that ATO might downregulate MMP9 expression in PBMCs obtained from LN patients during disease remission (n = 3). Conclusion ATO interacts with immune cells in LN patients via different inflammatory pathways and may downregulate MMP9 expression in PBMCs.

Galectin-3 Mediates NETosis and Acts as an Autoantigen in Systemic Lupus Erythematosus-Associated Diffuse Alveolar Haemorrhage.

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease with enhanced NETosis and impaired degradation of neutrophil extracellular traps (NETs). Galectin-3 is a β-galactoside binding protein and is associated with neutrophil functions as well as involved in mediating autoimmune disorders. In this study, we plan to examine the associations of galectin-3 with the pathogenesis of SLE and NETosis. Galectin-3 expression levels were determined in peripheral blood mononuclear cells (PBMCs) of SLE patients for the association with lupus nephritis (LN) or correlation of SLE disease activity index 2000 (SLEDAI-2K). NETosis was observed in human normal and SLE and murine galectin-3 knockout (Gal-3 KO) neutrophils. Gal-3 KO and wild-type (WT) mice induced by pristane were used to evaluate disease signs, including diffuse alveolar haemorrhage (DAH), LN, proteinuria, anti-ribonucleoprotein (RNP) antibody, citrullinated histone 3 (CitH3) levels, and NETosis. Galectin-3 levels are higher in PBMCs of SLE patients compared with normal donors and positively correlated with LN or SLEDAI-2K. Gal-3 KO mice have higher percent survival and lower DAH, LN proteinuria, and anti-RNP antibody levels than WT mice induced by pristane. NETosis and citH3 levels are reduced in Gal-3 KO neutrophils. Furthermore, galectin-3 resides in NETs while human neutrophils undergo NETosis. Galectin-3-associated immune complex deposition can be observed in NETs from spontaneously NETotic cells of SLE patients. In this study, we provide clinical relevance of galectin-3 to the lupus phenotypes and the underlying mechanisms of galectin-3-mediated NETosis for developing novel therapeutic strategies targeting galectin-3 for SLE.

Humanized BAFF transgenic mice develop autoimmune manifestations

Abstract The B cell activating factor(BAFF) is a B cell survival factor that supports autoreactive B cells’ survival and prevents their depletion. Excessive BAFF can increase autoreactive B cells, driving autoimmunity. BAFF is commonly overexpressed in Systemic Lupus Erythematosus(SLE) and is strongly involved in the pathogenesis of the disease. Mice with BAFF deficiency results in the lack of mature B cells, whereas mice that overproduce BAFF have high numbers of mature B cells and antibodies, including autoantibodies, and develop an autoimmune disease similar to SLE in humans. BAFF has been shown to be the pivotal target in autoimmune diseases. In this study, we report the generation of two transgenic mouse strains with overexpression of human BAFF (B6-hBAFF, T036791 and T036794), which could be used to study anti-BAFF therapies. Overexpression of human BAFF led to significantly increased IgG, IgA, and IgM levels since 6 weeks of age compared with wild-type mice, which continued to increase gradually as the transgenic mice aged. These mice secreted a high level of anti-DNA autoantibodies, along with an increased ratio of B cells/CD45 +in the spleen and lymph node compared with wild-type mice, indicating overreactive B cells. Proteinuria started at 6 weeks of age with an increase in protein/creatinine ratio. This was accompanied by the infiltration of inflammatory leukocytes in the kidney at 15 weeks of age, suggesting local kidney inflammation. Taken together, the humanized BAFF transgenic mice autoimmune manifestations with enhanced overreactive B cells, providing a valuable tool supporting preclinical efficacy studies of drugs targeting B cells for the development of autoimmune disease therapies.

Single-cell Spatial Phenotyping of Immune and Metabolic Landscapes in Systemic Lupus Erythematosus

Abstract Autoimmune diseases like systemic lupus erythematosus (SLE) affect the health of multiple organ systems including the central nervous system, skin, joints, and kidneys. The heterogeneity of clinical profiles observed with SLE reflects a complex dysregulation of cellular processes, including metabolism, apoptotic clearance, and inflammation. Diagnosis and treatment of SLE is thus challenging, and few new treatments have been approved over the past 60 years. In this study, we aimed to characterize the spatial immune and metabolic profiles of SLE at single cell resolution. To do so, we profiled a cohort of human FFPE SLE tissues with an ultrahigh-plex panel of >50 oligo-conjugated antibodies representing immune, apoptotic, metabolic and stress markers. Whole-slide, spatial phenotyping was performed using the PhenoCycler ®-Fusion system, followed by deep bioinformatic analyses to determine the cellular phenotypes, spatial neighborhoods, and metabolic determinants of SLE. By combining immune cell lineage information with expression of key proteins involved in glycolysis, amino acid metabolism, lipid metabolism, hypoxia, oxidative stress, and apoptosis, we elucidated the functional dysregulation in key immune subsystems that may contribute to development of autoimmunity and inflammation associated with SLE. Spatial phenotyping also revealed a high degree of inter- and intra-sample heterogeneity, confirming the complexity of the SLE clinical profile. Collectively, our data amount to new insights into metabolic reprogramming of immune cells in autoimmune diseases and may aid in the identification of novel therapeutic biomarkers within the tissue microenvironment of SLE patients.

IL-4 role in the development of the lupus mouse model induced by non-bilayer phospholipids arrangements

Abstract Non-bilayer phospholipids arrangements (NPAs) are lipid molecular associations that are different from the bilayer and are transient. However, if they become stable, they can trigger a disease in mice that is similar to human systemic lupus erythematosus. NPAs can be stabilized in liposomes formed by cylindrical and conical lipids or in cell membranes by drugs such as procainamide or chlorpromazine. In wild-type BALB/c mice, this lupus model has been developed by administering liposomes with NPAs induced and stabilized with procainamide or chlorpromazine, by administering the drugs alone or by administering the monoclonal antibody H308; these last two procedures stabilize the NPAs in the membranes of mouse cells. Anti-NPAs, anti-cardiolipin, anti-histones and anti-coagulants auto-antibodies have been detected in the serum of these mice; in addition, the mice present facial lesions and alterations in the skin and kidney. In this work, we evaluated the participation of the T H2 response, through IL-4, which is its most characteristic cytokine, in the development of the NPAs-induced lupus model in mice. Wild type or IL-4 knockout BALB/c mice were administered with liposomes bearing drug-induced NPAs, the drugs alone, or anti-NPA H308 antibody to induce the lupus-like disease. IL-4 KO mice showed minor disease manifestations, compared to wild-type mice, with decreased production of anti-NPA IgG antibodies, no anti-cardiolipin, anti-histones and anticoagulant antibodies, and no kidney or skin lesions. In these mice, H308 was the only inducer of anti-NPA IgG antibodies. These findings suggest that IL-4 has a key role in the development of the murine lupus-like disease induced by NPA stabilization. This study was supported by grants from IPN (SIP20232128, SIP20232132 and SIP20232135).

The transcription factor Mef2d regulates B:T synapse-dependent GC-TFH differentiation and IL-21-mediated humoral immunity.

Communication between CD4 T cells and cognate B cells is key for the former to fully mature into germinal center-T follicular helper (GC-TFH) cells and for the latter to mount a CD4 T cell-dependent humoral immune response. Although this interaction occurs in a B:T synapse-dependent manner, how CD4 T cells transcriptionally regulate B:T synapse formation remains largely unknown. Here, we report that Mef2d, an isoform of the myocyte enhancer factor 2 (Mef2) transcription factor family, is a critical regulator of this process. In CD4 T cells, Mef2d negatively regulates expression of Sh2d1a, which encodes SLAM-associated protein (SAP), a critical regulator of B:T synapses. We found that Mef2d regulates Sh2d1a expression via DNA binding-dependent transcriptional repression, inhibiting SAP-dependent B:T synapse formation and preventing antigen-specific CD4 T cells from differentiating into GC-TFH cells. Mef2d also impeded IL-21 production by CD4 T cells, an important B cell help signaling molecule, via direct repression of the Il21 gene. In contrast, CD4 T cell-specific disruption of Mef2d led to a substantial increase in GC-TFH differentiation in response to protein immunization, concurrent with enhanced SAP expression. MEF2D mRNA expression inversely correlates with human systemic lupus erythematosus (SLE) patient autoimmune parameters, including circulating TFH-like cell frequencies, autoantibodies, and SLEDAI scores. These findings highlight Mef2d as a pivotal rheostat in CD4 T cells for controlling GC formation and antibody production by B cells.

De Novo PACSIN1 Gene Variant Found in Childhood Lupus and a Role for PACSIN1/TRAF4 Complex in Toll-like Receptor 7 Activation.

Increased Toll-like receptor 7 (TLR-7) signaling leading to the production of type I interferon (IFN) is an important contributor to human systemic lupus erythematosus (SLE). Protein kinase C and casein kinase substrate in neurons 1 (PACSIN1), a molecule that regulates synaptic vesicle recycling, has been linked to TLR-7/TLR-9-mediated type I IFN production in humans and mice, but the underlying mechanism is unknown. We undertook this study to explore the pathogenicity and underlying mechanism of a de novo PACSIN1 missense variant identified in a child with SLE. PACSIN1 Q59K de novo and null variants were introduced into a human plasmacytoid dendritic cell line and into mice using CRISPR/Cas9 editing. The effects of the variants on TLR-7/TLR-9 signaling in human and mouse cells, as well as PACSIN1 messenger RNA and IFN signature in SLE patients, were assessed using real-time polymerase chain reaction and flow cytometry. Mechanisms were investigated using luciferase reporter assays, RNA interference, coimmunoprecipitation, and immunofluorescence. We established that PACSIN1 forms a trimolecular complex with tumor necrosis factor receptor-associated factor 4 (TRAF4) and TRAF6 that is important for the regulation of type I IFN. The Q59K mutation in PACSIN1 augments binding to neural Wiskott-Aldrich syndrome protein while it decreases binding to TRAF4, leading to unrestrained TRAF6-mediated activation of type I IFN. Intriguingly, PACSIN1 Q59K increased TLR-7 but not TLR-9 signaling in human cells, leading to elevated expression of IFNβ and IFN-inducible genes. Untreated SLE patients had high PACSIN1 expression in peripheral blood cells that correlated positively with IFN-related genes. Introduction of the Pacsin1 Q59K mutation into mice caused increased surface TLR-7 and TRAIL expression in B cells. PACSIN1 Q59K increases IFNβ activity through the impairment of TRAF4-mediated inhibition of TLR-7 signaling, possibly contributing to SLE risk.

Deficient leptin receptor signaling in T cells of human SLE.

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease mainly mediated by IgG autoantibody. While follicular helper T (Tfh) cells are crucial for supporting IgG autoantibody generation in human SLE, underlying mechanisms for Tfh cell mal-differentiation remain unclear. In total, 129 SLE patients and 37 healthy donors were recruited for this study. Circulating leptin was determined by ELISA from patients with SLE and healthy individuals. CD4 T cells isolated from SLE patients and healthy donors were activated with anti-CD3/CD28 beads under cytokine-unbiased conditions in the presence or absence of recombinant leptin protein, followed by detection for Tfh cell differentiation by quantifying intracellular transcription factor Bcl-6 and cytokine IL-21. AMPK activation was assessed by analyzing phosphor-AMPK using phosflow cytometry and immunoblots. Leptin receptor expression was determined using flow cytometry and its overexpression was achieved by transfection with an expression vector. Humanized SLE chimeras were induced by injecting patients' immune cells into immune-deficient NSG mice and used for translational studies. Circulating leptin was elevated in patients with SLE, inversely associated with disease activity. In healthy individuals, leptin efficiently inhibited Tfh cell differentiation through inducing AMPK activation. Meanwhile, leptin receptor deficiency was a feature of CD4 T cells in SLE patients, impairing the inhibitory effect of leptin on the differentiation of Tfh cells. As a result, we observed the coexistence of high circulating leptin and increased Tfh cell frequencies in SLE patients. Accordingly, overexpression of leptin receptor in SLE CD4 T cells abrogated Tfh cell mal-differentiation and IgG anti-dsDNA generation in humanized lupus chimeras. Leptin receptor deficiency blocks the inhibitory effect of leptin on SLE Tfh cell differentiation, serving as a promising therapeutic target for lupus management.

LncRNA GAS5 as an Inflammatory Regulator Acting through Pathway in Human Lupus.

To investigate the contribution of GAS5 in the pathogenesis of SLE. Systemic Lupus Erythematosus (SLE) is characterized by aberrant activity of the immune system, leading to variable clinical symptoms. The etiology of SLE is multifactor, and growing evidence has shown that long noncoding RNAs (lncRNAs) are related to human SLE. Recently, lncRNA growth arrest-specific transcript 5 (GAS5) has been reported to be associated with SLE. However, the mechanism between GAS5 and SLE is still unknown. Find the specific mechanism of action of lncRNA GAS5 in SLE. Collecting samples of the SLE patients, Cell culture and treatment, Plasmid construction, and transfection, Quantitative real-time PCR analysis, Enzyme-linked immunosorbent assay (ELISA), Cell viability analysis, Cell apoptosis analysis, Western blot. In this research, we investigated the contribution of GAS5 in the pathogenesis of SLE. We confirmed that, compared to healthy people, the expression of GAS5 was significantly decreased in peripheral monocytes of SLE patients. Subsequently, we found that GAS5 can inhibit the proliferation and promote the apoptosis of monocytes by over-expressing or knocking down the expression of GAS5. Additionally, the expression of GAS5 was suppressed by LPS. Silencing GAS5 significantly increased the expression of a group of chemokines and cytokines, including IL-1β, IL-6, and THFα, which were induced by LPS. Furthermore, it was identified the involvement of GAS5 in the TLR4-mediated inflammatory process was through affecting the activation of the MAPK signaling pathway. In general, the decreased GAS5 expression may be a potential contributor to the elevated production of a great number of cytokines and chemokines in SLE patients. And our research suggests that GAS5 contributes a regulatory role in the pathogenesis of SLE, and may provide a potential target for therapeutic intervention.