Mouse Model Of Lupus Research Articles

Promise and complexity of lupus mouse models.

As a follow up to a 2010 meeting deliberating on the benefits of studying mouse models of systemic lupus erythematosus (SLE), the virtual conference “Mouse models of lupus 10 years later” convened on 10 December 2020 to address a challenging decade that saw few new therapies approved, despite leaps in knowledge.

The role of the mitochondrial voltage‐dependent anion channel in obesity and inflammation

Stressed mitochondria can release mitochondrial DNA (mtDNA) into the cytosol via the mitochondrial outer membrane (MOM), where it interacts with and activates a large number of immunostimulatory DNA sensors, which can promote inflammation and metabolic disorders. The voltage-dependent anion channel (VDAC), which in the mammalian mitochondria is represented by three isoforms (VDAC1, VDAC2, and VDAC3), is the most abundant protein in the MOM and regulates metabolism, inflammasome activation, and the type-I interferon signaling pathway. We found that VDAC-mediated cytosolic mtDNA release can activate the type-I interferon signaling pathway and cause obesity and autoimmune diseases such as systemic lupus erythematosus (SLE). The VDAC oligomerization inhibitor VBIT-4 decreases both adipogenesis and weight gain in leptin-deficient (ob/ob) mice. Also, in a mouse model of lupus, VBIT-4 ameliorated lupus-like symptoms through diminishing mtDNA release and NETosis. Our findings support VDAC oligomerization as a new therapeutic target for obesity and inflammatory disease associated with mtDNA release.

Blockade of checkpoint ILT3/LILRB4/gp49B binding to fibronectin ameliorates autoimmune disease in BXSB/Yaa mice

Abstract Extracellular matrix (ECM) not only provides a supporting framework for each tissue, but also elicits cellular responses by providing an inductive substrate. Fibronectin (FN), a major ECM macromolecule, is composed of multiple modules that interact with ECM-associated proteins, plasma proteins, and cell-surface proteins to ensure its modulatory roles. Here we revealed that FN is identified as a physiological ligand of the immunoglobulin (Ig)-like transcript 3/leukocyte Ig-like receptor B4 (ILT3/LILRB4) which serves as an immune checkpoint for autoimmune and cancer diseases. Human LILRB4 and the murine ortholog, gp49B, bound FN with sub-micromolar affinities as assessed by bio-layer interferometry. The major LILRB4-binding site in FN was located at the N-terminal 30-kDa module (FN30). Blockade of B4–FN binding with gp49 antibody or a recombinant FN30-Fc fusion protein reduced the secretion of pathogenic IgG autoantibodies, thereby reducing PAS-positive glomerular deposition in lupus-prone BXSB/Yaa mice. Compared with the control group, activation-induced cytidine deaminase (AID) expression in splenic activated B cells of FN30-Fc-treated BXSB/Yaa mice was decreased, indicating gp49B-FN30 signaling contributes in the class switch recombination (CSR) of Ig genes. These results suggested that gp49B–FN interplay is critical for pathogenic autoantibodies-mediated glomerulonephritis in the BXSB/Yaa lupus mouse model.

Distinct spatial profile of inflammatory gene expression in the brain of a mouse model of neuropsychiatric lupus

Abstract Systemic Lupus Erythematosus (SLE) is an incurable autoimmune disease that results in central nervous system (CNS) involvement in up to 80% of patients, with clinical manifestations ranging from anxiety and fatigue to overt psychosis. However, the mechanisms and cellular components underlying these neuropsychiatric symptoms (NPSLE) remain largely unknown. An elevated type 1 interferon (IFN) signature has been commonly observed in SLE patients, particularly within the CNS of NPSLE patients (Crow et. al., 2014, Shiozawa et. al., 1992). Given the diversity of clinical CNS manifestations, we hypothesized that type 1 interferon-mediated inflammation occurs in spatially distinct regions within the CNS, resulting in differential behavioral outcomes depending on the impacted brain region. To test this hypothesis, we first characterized behavioral phenotypes in the Sle1, Yaa mouse model, and show that these mice exhibit anxiety-like, and fatigue-like behaviors consistent with the major clinical manifestations of NPSLE. To assess the spatial distribution of inflammatory gene expression, we utilized MERFISH (Moffitt et. al., 2016), a multiplexed spatial transcriptomics platform, and observed strikingly distinct patches of interferon stimulated gene (ISG) expression within the subcortical regions of Sle1, Yaa mouse brains. Preliminary single nucleus sequencing (sNuc-Seq) and in situ hybridization results implicate astrocytes and oligodendrocytes as the major cell classes enriched in these ISG patches. In summary, our results validate a mouse behavioral model of NPSLE, and show spatially distinct regions of ISG expression within the CNS, opening up a new avenue of investigation into the fundamental mechanisms of NPSLE.

Kidney macrophages in human lupus nephritis and mouse models express conserved inflammatory and remodeling gene programs and localize to the same anatomic sub-compartments.

Abstract Tissue macrophages promote kidney homeostasis through tightly regulated initiation, maintenance, and resolution of tissue repair. In lupus nephritis (LN), kidney macrophages may drive damage in glomeruli and other kidney sub-compartments leading to proteinuria and fibrosis. Recent single-cell RNA sequencing work uncovered 4 novel kidney macrophage subsets in LN patient biopsies: M2-like “reparative”, “inflammatory”, “phagocytic”, and “resident” subsets. But how macrophage gene programs translate into cellular functions driving proximal tissue damage has been difficult to study because we do not fully understand how mouse models recapitulate human LN. Here, we used single cell RNA sequencing to identify kidney macrophage subsets conserved in human and mouse models of LN. We compared the transcriptomes of macrophages collected from human LN patients at peak clinical disease to those from 4 mouse strains at early and peak clinical disease. We discovered that human “reparative”, “inflammatory”, “phagocytic” subsets were conserved across species. In particular, human “reparative” and mouse resident macrophages shared inflammatory and remodeling programs, expressed interferon stimulated genes, and localized to the same kidney sub-compartments. In nephritic mice, this subset converted to a mixed M1-inflammatory/M2-repair phenotype also observed in humans, thus identifying potential conserved programs driving tissue damage in mice and humans. These findings strongly support shared roles for conserved human and mouse macrophages. Critically, they open a new path utilizing mice to study how conserved programs translate into cellular functions driving proximal tissue damage.

Type I interferon enhanced double negative 2 B cell differentiation and lupus autoantibody production

Abstract Systemic Lupus Erythematosus (SLE) is characterized by high level of type I interferon (IFN) and abnormal expansion of effector B cells including IgD−CD27−double negative (DN), CD21−T-bet+DN2 B cells, and antibody secreting cells (ASCs). It remains unclear as to the role of type I and type II interferon (IFN) to promote DN2 B cell differentiation. The in vivo effects of type I IFN signaling in promoting DN B cells were accessed using the BXD2 mouse model of lupus which exhibit a low Th1 response, compared to normal B6 mice. Compared to normal B6 mouse, there was a significantly elevated percent of DN B cells in the BXD2 mice, but this was reduced in BXD2 mice that are deficient in IFNAR1 (BXD2-Ifnar1−/−). Compared to wild-type BXD2 mice, there was a lower level of IgG autoantibodies specific to DNA, histone and Smith (Sm) in BXD2-Ifnar1−/− mice. BXD2-Ifnar1−/− B cells presented impaired differentiation into the DN and the DN2 populations under an in vitro stimulation condition in the presence of IFNb and a TLR7 agonist. To determine if type I IFN stimulation can direct differentiation of healthy B cells to these effector B cells without the influence of type II IFN, B cells purified from healthy individuals were stimulated under a DN stimulation condition (anti-Ig+IL-21+BAFF+TLR7) in the presence and absence of IFNb. We found that IFNb significantly increased the percentage and of DN and DN2 B cells, but decreased the percentage of CD27+CD38+ plasmablasts/plasma. Under the same condition, IFNb increased the secretion of autoantibodies specific to DNA, histone and Sm. Our results suggest that type I IFN signaling stimulates DN2 B cell differentiation and can promote the abnormal expansion of these B cells in vivo independent of type II IFN.

Evaluation of immunomodulatory effects of mesenchymal stem cell on pristane-induced lupus mouse model

Evaluation of immunomodulatory effects of mesenchymal stem cell on pristane-induced lupus mouse model

019 Vgll3 causes discoid lupus-like fibrosis in a mouse model of lupus

019 Vgll3 causes discoid lupus-like fibrosis in a mouse model of lupus

Etanercept prevents TNF-α mediated mandibular bone loss in FcγRIIb-/- lupus model.

Patients with systemic lupus erythematosus are at increased risk for alveolar bone loss due to periodontitis possibly as a result of a pathogenic immune response to oral bacteria and inflammation. The aim of the present study was to investigate whether an anti-TNF-α antagonist could prevent mandibular bone loss in the FcγRIIb-/- mouse model of lupus. Mice lacking FcγRIIb had decreased cancellous and cortical bone volume at 6 months of age. Etanercept increased cancellous but not cortical bone volume in WT and increased both cancellous bone volume and cortical thickness in FcγRIIb-deficient mice. FcγRIIb deficiency decreased mRNA levels for osteoblast marker genes, Osx, Col1a1 and Alp without any change in osteoclast marker genes. Etanercept increased Osx, Alp, and Ocn in both WT and FcγRIIb-/- mice. Osteoclast marker genes including TNF-α, Trap and RANKL/OPG ratio was decreased in WT. Serum markers of proinflammatory cytokines, TNF-α, IFNγ, IL-6, and IL-17A, were increased in FcγRIIb-/- mice and etanercept antagonized these effects in FcγRIIb-/- mice. Etanercept increased serum PTH levels in the FcγRIIb-/- mouse model of lupus. Our results suggest that deletion of FcγRIIb induces osteopenia by increasing the level of proinflammatory cytokines. Etanercept is effective in preventing mandibular bone loss in FcγRIIb-/- mice, suggesting that anti-TNF-α therapy may be able to ameliorate mandibular bone loss in SLE patients with periodontitis.

Interleukin-12 exacerbates symptoms in an MRL/MpJ-Faslpr mouse model of systemic lupus erythematosus.

Interleukin (IL)-12 modulates the generation and function of a variety of immune cells and serves an important role in the pathogenesis of autoimmune diseases. However, the precise role of IL-12 in the pathogenesis of systemic lupus erythematosus (SLE) remains to be elucidated. In the present study, the serum levels of IL-12 in patients with SLE were determined using an ELISA. The association between serum levels of IL-12 and clinical and laboratory indices, specifically, disease activity and complement 3, were analyzed. Recombinant IL-12 or an anti-IL-12 antibody was used to treat the MRL/MpJ-Faslpr mouse model of systemic lupus erythematosus. The glomerulonephritis and inflammatory cell infiltration was examined to evaluate histological changes using hematoxylin and eosin and Periodic acid-Schiff staining. Serum creatinine and proteinuria were used to determine renal function. The levels of anti-double stranded DNA and anti-nuclear autoantibodies were assessed. The results demonstrated that serum levels of IL-12 were markedly increased in patients with SLE compared with controls and in lupus model mice in comparison with control mice. The serum levels of IL-12 increased with disease severity in patients with SLE. SLE-like symptoms were exacerbated in lupus model mice treated with exogenous IL-12. However, SLE-like symptoms were ameliorated in lupus model mice treated with an anti-IL-12 antibody. The present results demonstrated that IL-12 aggravated SLE and anti-IL12 antibodies ameliorated SLE. The present data suggest that blocking IL-12 may be a beneficial therapeutic strategy to halt the progression of lupus nephritis.

Endoplasmic reticulum stress sensor IRE1α propels neutrophil hyperactivity in lupus.

Neutrophils amplify inflammation in lupus through the release of neutrophil extracellular traps (NETs). The endoplasmic reticulum stress sensor inositol-requiring enzyme 1 α (IRE1α) has been implicated as a perpetuator of inflammation in various chronic diseases; however, IRE1α has been little studied in relation to neutrophil function or lupus pathogenesis. Here, we found that neutrophils activated by lupus-derived immune complexes demonstrated markedly increased IRE1α ribonuclease activity. Importantly, in neutrophils isolated from patients with lupus, we also detected heightened IRE1α activity that was correlated with global disease activity. Immune complex-stimulated neutrophils produced both mitochondrial ROS (mitoROS) and the activated form of caspase-2 in an IRE1α-dependent fashion, whereas inhibition of IRE1α mitigated immune complex-mediated NETosis (in both human neutrophils and a mouse model of lupus). Administration of an IRE1α inhibitor to lupus-prone MRL/lpr mice over 8 weeks reduced mitoROS levels in peripheral blood neutrophils, while also restraining plasma cell expansion and autoantibody formation. In summary, these data identify a role for IRE1α in the hyperactivity of lupus neutrophils and show that this pathway is upstream of mitochondrial dysfunction, mitoROS formation, and NETosis. We believe that inhibition of the IRE1α pathway is a novel strategy for neutralizing NETosis in lupus, and potentially other inflammatory conditions.

A STING antagonist modulating the interaction with STIM1 blocks ER-to-Golgi trafficking and inhibits lupus pathology

BackgroundNucleic acids are potent stimulators of type I interferon (IFN-I) and antiviral defense, but may also promote pathological inflammation. A range of diseases are characterized by elevated IFN-I, including systemic lupus erythematosus (lupus). The DNA-activated cGAS-STING pathway is a major IFN-I-inducing pathway, and activation of signaling is dependent on trafficking of STING from the ER to the Golgi. MethodsHere we used cell culture systems, a mouse lupus model, and material from lupus patients, to explore the mode of action of a STING antagonistic peptide, and its ability to modulate disease processes. FindingsWe report that the peptide ISD017 selectively inhibits all known down-stream activities of STING, including IFN-I, inflammatory cytokines, autophagy, and apoptosis. ISD017 blocks the essential trafficking of STING from the ER to Golgi through a mechanism dependent on the STING ER retention factor STIM1. Importantly, ISD017 blocks STING activity in vivo and ameliorates disease development in a mouse model for lupus. Finally, ISD017 treatment blocks pathological cytokine responses in cells from lupus patients with elevated IFN-I levels. InterpretationThese data hold promise for beneficial use of STING-targeting therapy in lupus. FundingThe Novo Nordisk Foundation, The European Research Council, The Lundbeck Foundation, European Union under the Horizon 2020 Research, Deutsche Forschungsgemeinschaft, Chulalongkorn University.

Recent Advances in Lupus B Cell Biology: PI3K, IFNγ, and Chromatin.

In the autoimmune disease Systemic Lupus Erythematosus (SLE), autoantibodies are formed that promote inflammation and tissue damage. There has been significant interest in understanding the B cell derangements involved in SLE pathogenesis. The past few years have been particularly fruitful in three domains: the role of PI3K signaling in loss of B cell tolerance, the role of IFNγ signaling in the development of autoimmunity, and the characterization of changes in chromatin accessibility in SLE B cells. The PI3K pathway coordinates various downstream signaling molecules involved in B cell development and activation. It is governed by the phosphatases PTEN and SHIP-1. Murine models lacking either of these phosphatases in B cells develop autoimmune disease and exhibit defects in B cell tolerance. Limited studies of human SLE B cells demonstrate reduced expression of PTEN or increased signaling events downstream of PI3K in some patients. IFNγ has long been known to be elevated in both SLE patients and mouse models of lupus. New data suggests that IFNγR expression on B cells is required to develop autoreactive germinal centers (GC) and autoantibodies in murine lupus. Furthermore, IFNγ promotes increased transcription of BCL6, IL-6 and T-bet in B cells, which also promote GC and autoantibody formation. IFNγ also induces epigenetic changes in human B cells. SLE B cells demonstrate significant epigenetic reprogramming, including enhanced chromatin accessibility at transcription factor motifs involved in B cell activation and plasma cell (PC) differentiation as well as alterations in DNA methylation and histone modifications. Histone deacetylase inhibitors limit disease development in murine lupus models, at least in part via their ability to prevent B cell class switching and differentiation into plasma cells. This review will discuss relevant discoveries of the past several years pertaining to these areas of SLE B cell biology.

D-mannose ameliorates autoimmune phenotypes in mouse models of lupus

BackgroundSystemic lupus erythematosus is an autoimmune disease characterized by an overproduction of autoantibodies resulting from dysregulation in multiple immune cell types. D-mannose is a C− 2 epimer of glucose that exhibits immunoregulatory effects in models of autoimmune diseases, such as type 1 diabetes, induced rheumatoid arthritis, and airway inflammation. This study was conducted to evaluate the efficacy of D-mannose treatment in mouse models of lupus.ResultsFirstly, the effect of D-Mannose was evaluated by flow cytometry on the in vitro activation of non-autoimmune C57BL/6 (B6) bone marrow-derived dendritic cells (BMDCs) and their ability to induce antigen-specific CD4+ T cell proliferation and activation. D-mannose inhibited the maturation of BMDCs and their induction of antigen-specific T cell proliferation and activation. In vivo, D-mannose increased the frequency of Foxp3+ regulatory T cells in unmanipulated B6 mice. To assess the effect of D-mannose in mouse models of lupus, we used the graft-versus-host disease (cGVHD) induced model and the B6.lpr spontaneous model. In the cGVHD model, D-mannose treatment decreased autoantibody production, with a concomitant reduction of the frequency of effector memory and follicular helper T cells as well as germinal center B cells and plasma cells. These results were partially validated in the B6.lpr model of spontaneous lupus.ConclusionOverall, our results suggest that D-mannose ameliorates autoimmune activation in models of lupus, at least partially due to its expansion of Treg cells, the induction of immature conventional dendritic cells and the downregulation of effector T cells activation. D-Mannose showed however a weaker immunomodulatory effect in lupus than in other autoimmune diseases.

Human umbilical cord-derived mesenchymal stem cell therapy ameliorates lupus through increasing CD4+ T cell senescence via MiR-199a-5p/Sirt1/p53 axis.

Rationale: Although human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) transplantation has been proved to be an effective therapeutic approach to treat systemic lupus erythematosus (SLE), the detailed underlying mechanisms are not fully understood. Transferring miRNAs is one mean by which MSCs communicate with surrounding cells. Sirt1 is a NAD-dependent deacetylase that protects against cell senescence by deacetylating p53. Here we aimed to explore whether hUC-MSCs affected senescence of splenic CD4+ T cells through regulating Sirt1/p53 via miRNA in the MRL/lpr lupus mouse model.Methods: The effects of hUC-MSCs on lupus syndrome and senescence pathways in MRL/lpr mice in vivo and in vitro were determined. The functional roles of miR-199a-5p in splenic CD4+ T cell senescence were studied by miRNA mimic or inhibitor in vitro. MRL/lpr mice were injected with miR-199a-5p agomir to evaluate the effects of miR-199a-5p on splenic CD4+ T cell senescence and disease in vivo.Results: We showed that hUC-MSCs transplantation ameliorated lupus symptoms and increased senescence of splenic CD4+ T cells through Sirt1/p53 signaling via miR-199a-5p in MRL/lpr mice. Moreover, systemic delivery of miR-199a-5p in MRL/lpr mice increased splenic CD4+ T-cell senescence, mimicking the therapeutic effects of transplanted hUC-MSCs.Conclusions: We have identified miR-199a-5p as one of the mechanisms employed by hUC-MSCs to alleviate lupus disease associated pathologies in MRL/lpr mice, which is attributable for promoting splenic CD4+ T cell senescence through Sirt1/p53 pathway.

Shared inflammatory and skin-specific gene signatures reveal common drivers of discoid lupus erythematosus in canines, humans and mice

Autoimmune skin diseases are complex and are thought to arise from a combination of genetics and environmental exposures, which trigger an ongoing immune response against self-antigens. Companion animals including cats and dogs are known to develop inflammatory skin conditions similar to humans and share the same environment, providing opportunities to study spontaneous disease that encompasses genetic and environmental factors with a One Health approach. A strength of comparative immunology approaches is that immune profiles may be assessed across different species to better identify shared or conserved pathways that might drive inflammation. Here, we performed a comparative study of skin from canine discoid lupus erythematosus (DLE) using NanoString nCounter technology. We compared these gene expression patterns to those of human DLE and a mouse model of cutaneous lupus. We found strong interferon signatures, with CXCL10, ISG15, and an S100 gene family member among the highest, most significant DEGs upregulated across species. Cell type analysis revealed marked T-cell and B-cell infiltration. Interestingly, canine DLE samples also recapitulated downregulated skin homeostatic genes observed in human DLE. We conclude that spontaneous DLE in dogs captures many features that are present in human disease and may serve as a more complete model for conducting further genomic and/or transcriptomic studies.

Discovery of M5049: A Novel Selective Toll-Like Receptor 7/8 Inhibitor for Treatment of Autoimmunity.

Toll-like receptor (TLR) 7 and TLR8 are transmembrane receptors that recognize single-stranded RNA. Activation of these receptors results in immune cell stimulation and inflammatory cytokine production, which is normally a protective host response. However, aberrant activation of TLR7/8 is potentially pathogenic and linked to progression of certain autoimmune diseases such as lupus. Thus, we hypothesize that an inhibitor that blocks TLR7/8 would be an effective therapeutic treatment. Prior efforts to develop inhibitors of TLR7/8 have been largely unsuccessful as a result of the challenge of producing a small-molecule inhibitor for these difficult targets. Here, we report the characterization of M5049 and compound 2, molecules which were discovered in a medicinal chemistry campaign to produce dual TLR7/8 inhibitors with drug-like properties. Both compounds showed potent and selective activity in a range of cellular assays for inhibition of TLR7/8 and block synthetic ligands and natural endogenous RNA ligands such as microRNA and Alu RNA. M5049 was found to be potent in vivo as TLR7/8 inhibition efficaciously treated disease in several murine lupus models and, interestingly, was efficacious in a disease context in which TLR7/8 activity has not previously been considered a primary disease driver. Furthermore, M5049 had greater potency in disease models than expected based on its in vitro potency and pharmacokinetic/pharmacodynamic properties. Because of its preferential accumulation in tissues, and ability to block multiple TLR7/8 RNA ligands, M5049 may be efficacious in treating autoimmunity and has the potential to provide benefit to a variety of patients with varying disease pathogenesis. SIGNIFICANCE STATEMENT: This study reports discovery of a novel toll-like receptor (TLR) 7 and TLR8 inhibitor (M5049); characterizes its binding mode, potency/selectivity, and pharmacokinetic and pharmacodynamic properties; and demonstrates its potential for treating autoimmune diseases in two mouse lupus models. TLR7/8 inhibition is unique in that it may block both innate and adaptive autoimmunity; thus, this study suggests that M5049 has the potential to benefit patients with autoimmune diseases.

VDAC1 in the diseased myocardium and the effect of VDAC1-interacting compound on atrial fibrosis induced by hyperaldosteronism

The voltage-dependent anion channel 1 (VDAC1) is a key player in mitochondrial function. VDAC1 serves as a gatekeeper mediating the fluxes of ions, nucleotides, and other metabolites across the outer mitochondrial membrane, as well as the release of apoptogenic proteins initiating apoptotic cell death. VBIT-4, a VDAC1 oligomerization inhibitor, was recently shown to prevent mitochondrial dysfunction and apoptosis, as validated in mouse models of lupus and type-2 diabetes. In the present study, we explored the expression of VDAC1 in the diseased myocardium of humans and rats. In addition, we evaluated the effect of VBIT-4 treatment on the atrial structural and electrical remodeling of rats exposed to excessive aldosterone levels. Immunohistochemical analysis of commercially available human cardiac tissues revealed marked overexpression of VDAC1 in post-myocardial infarction patients, as well as in patients with chronic ventricular dilatation\\dysfunction. In agreement, rats exposed to myocardial infarction or to excessive aldosterone had a marked increase of VDAC1 in both ventricular and atrial tissues. Immunofluorescence staining indicated a punctuated appearance typical for mitochondrial-localized VDAC1. Finally, VBIT-4 treatment attenuated the atrial fibrotic load of rats exposed to excessive aldosterone without a notable effect on the susceptibility to atrial fibrillation episodes induced by burst pacing. Our results indicate that VDAC1 overexpression is associated with myocardial abnormalities in common pathological settings. Our data also indicate that inhibition of the VDAC1 can reduce excessive fibrosis in the atrial myocardium, a finding which may have important therapeutic implications. The exact mechanism\\s of this beneficial effect need further studies.

Atherosclerotic plaque vulnerability is increased in mouse model of lupus

Anti-apolipoprotein A-1 (anti-apoA-1 IgG) and anti-double stranded DNA (anti-dsDNA IgG) autoantibodies have been described as mediators of atherogenesis in mice and humans. In the present study, we aim to investigate the association between atherosclerotic parameters, autoantibodies and plaque vulnerability in the context of systemic lupus erythematosus (SLE). We therefore bred a lupus prone-mouse model (Nba2.Yaa mice) with Apoe−/− mice resulting in Apoe−/−Nba2.Yaa mice spontaneously producing anti-apoA-1 IgG antibodies. Although Apoe−/−Nba2.Yaa and Apoe−/− mice subject to a high cholesterol diet displayed similar atherosclerosis lesions size in aortic roots and abdominal aorta, the levels of macrophage and neutrophil infiltration, collagen, MMP-8 and MMP-9 and pro-MMP-9 expression in Apoe−/−Nba2.Yaa mice indicated features of atherosclerotic plaque vulnerability. Even though Apoe−/−Nba2.Yaa mice and Apoe−/− mice had similar lipid levels, Apoe−/−Nba2.Yaa mice showed higher anti-apoA-1 and anti-dsDNA IgG levels. Apoe−/−Nba2.Yaa mice displayed a reduction of the size of the kidney, splenomegaly and lymph nodes (LN) hypertrophy. In addition, anti-apoA-1 and anti-dsDNA IgG increased also in relation with mRNA levels of GATA3, IL-4, Bcl-6 and CD20 in the spleen and aortic arch of Apoe−/−Nba2.Yaa mice. Our data show that although atherosclerosis-lupus-prone Apoe−/−Nba2.Yaa mice did not exhibit exacerbated atherosclerotic lesion size, they did show features of atherosclerotic plaque destabilization in correlation with the increase of pro-atherogenic autoantibodies.

Type 1 Interferon Gene Signature Promotes RBC Alloimmunization in a Lupus Mouse Model.

Red blood cell (RBC) transfusion exposes recipients to hundreds of unmatched minor RBC antigens. This exposure can lead to production of alloantibodies that promote clinically significant hemolytic events. Multiple studies have reported an increased frequency of RBC alloimmunization in patients with autoimmunity. However, cellular and molecular mechanisms that underlie autoimmunity-induced alloimmunization have not been reported. Patients with systemic lupus erythematosus (SLE) have a high frequency of alloimmunization and express a type 1 interferon (IFNα/β) gene signature. Thus, we utilized the pristane-induced lupus mouse model to test the hypothesis that inflammation in lupus promotes RBC alloimmunization, and to examine the potential role of IFNα/β. Intraperitoneal injection of pristane, a hydrocarbon oil, led to autoantibody production, glomerulonephritis, and pulmonary hemorrhage in wild type (WT) mice. Pristane treatment significantly induced serum IFNα and expression of multiple interferon-stimulated genes (ISGs) in peripheral blood and peritoneal fluid cells, including inflammatory macrophages. Following transfusion with allogeneic RBCs expressing the KEL glycoprotein, pristane-treated WT mice produced significantly elevated levels of anti-KEL IgM and anti-KEL IgG, compared to untreated mice. Pristane induced comparable levels of inflammatory cells and cytokines in mice lacking the IFNα/β receptor (IFNAR1–/–) or the IFNα/β-inducing transcriptions factors (IRF3/7–/–), compared to WT mice. However, pristane-treated IFNAR1–/– and IRF3/7–/– mice failed to produce ISGs and produced significantly lower levels of transfusion-induced anti-KEL IgG, compared to WT mice. Thus, pristane induction of a lupus-like phenotype promoted alloimmunization to the KEL RBC antigen in an IFNα/β-dependent manner. To our knowledge, this is the first examination of molecular mechanisms contributing to RBC alloimmunization in a model of autoimmunity. These results warrant further investigation of the role of IFNα/β in alloimmunization to other RBC antigens and the contribution of the IFNα/β gene signature to the elevated frequency of alloimmunization in patients with SLE.