Lupus-prone Mice Research Articles

Infection with Opportunistic Bacteria Triggers Severe Pulmonary Inflammation in Lupus-Prone Mice.

Infection is a common cause of hospitalization and mortality in patients with systemic lupus erythematosus (SLE). How the underlying immune dysfunctions affect the antimicrobial immunity remains largely unknown. In the present study, employing the pulmonary infection model, we determined the antimicrobial defence of lupus-prone mice. After infecting with opportunistic bacterium Haemophilus influenzae (Hi), lupus-prone mice (B6/lpr) exhibited inefficient bacterial elimination and recovered slowly. They generated severer inflammation at the early stage of infection, as excessive accumulation of neutrophils and enhanced production of proinflammatory cytokines were observed in the lung. In addition, a large number of apoptotic cells were detected in the lungs of B6/lpr mice. For adaptive immune responses, B6/lpr mice were capable to generate enough protective Hi-specific Th17 cells. They evoked stronger Hi-specific γδ T17 response in both lungs and spleens. Unexpectedly, both CD4 and γδ T cells from lupus-prone mice showed deficiency in IFN-γ production. For humoral immune responses, compared with those of WT mice, the concentrations of Hi-specific IgA, IgM, and IgG, especially IgG, were significantly higher in the B6/lpr mice. Our findings suggest that lupus mice are capable to generate antibacterial immune responses; however, the overwhelming inflammation and overactivated immune responses increase the severity of infection.

Atializumab, a humanized anti-aminoacyl-tRNA synthetase-interacting multifunctional protein-1 (AIMP1) antibody significantly improves nephritis in (NZB/NZW) F1 mice

Aminoacyl-tRNA synthetase (ARS)-interacting multifunctional protein 1 (AIMP1) enhances the expression of proinflammatory cytokines. In our previous study, we have shown that serum AIMP1 in patients with SLE was significantly higher than that of healthy controls. To address whether neutralization of AIMP1 could ameliorate nephritis in lupus-prone mice, we generated atializumab, a humanized antibody against AIMP1 and investigated its therapeutic efficacy. ELISA showed that serum AIMP1 at 23 weeks old was significantly higher than that at 13 weeks old in lupus-prone mice. Therefore, lupus-prone mice were randomly assigned to 5 groups (vehicle, methylprednisolone and 0.5, 2, and 5 mg/kg atializumab). After treatment, disease severity was assessed using a variety of phenotypes, including proteinuria, histological damages, renal deposition of immune-complex. In addition, serum cytokines, anti-dsDNA and IgG subclasses were determined. T cell subsets were analyzed using a fluorescence-activated cell sorter. Atializumab significantly diminished proteinuria, improved glomerular and tubular damages and reduced the renal deposition of immune-complexes. Moreover, atializumab significantly decreased serum interferon (IFN)-γ, interleukin (IL)-17A, and IL-6, whereas it increased serum IL-10. Similarly, atializumab reduced the numbers of TH1, TH2 and TH17 cells in a dose-dependent manner, while atializumab enhanced the number of regulatory T (Treg) cells. Furthermore, atializumab decreased not only splenic plasma cells and serum anti-dsDNA but also pathogenic IgG subclasses for nephritis. It suppressed NF-κB activation by inhibiting IκBα degradation in a dose-dependent manner in vitro. Atializumab alleviated nephritis by inhibiting autoreactive T, B, and plasma cells and decreasing NF-κB-related proinflammatory cytokines in lupus-prone mice. These results suggest that treatment targeting AIMP1 could be a novel and highly immune-modulating therapeutic strategy in lupus nephritis.

Pim-1 as a Therapeutic Target in Lupus Nephritis.

Lupus nephritis (LN) is a major determinant of morbidity and mortality in systemic lupus erythematosus (SLE). Pim-1 regulates lymphocyte proliferation and activation. The role of Pim-1 in autoimmune disease remains unclear. This study was undertaken to test the hypothesis that inhibition of Pim-1 would have therapeutic potential in patients with LN. Pim-1 expression was analyzed in lupus-prone (NZB × NZW)F1 mice (n = 6), human peripheral blood mononuclear cells (PBMCs) from SLE patients (n = 10), and glomeruli from patients with LN (n = 8). The therapeutic effect of the Pim-1 inhibitor AZD1208 was assessed in the same murine lupus model (n = 10 mice per group). In vitro analysis was conducted to explore the mechanisms of action of Pim-1 in mouse and human podocytes after Pim-1 expression had been induced by anti-double-stranded DNA (anti-dsDNA) antibody-positive serum. Finally, MRL/lpr mice were used to confirm the therapeutic effects of Pim-1 inhibition in vivo (n = 10 mice per group). Up-regulation of Pim-1 was seen in renal lysates from diseased (NZB × NZW)F1 mice and in PBMCs from patients with SLE and renal biopsy tissue from patients with LN, relative to their control counterparts (each P < 0.05). The Pim-1 inhibitor AZD1208 reduced the severity of proteinuria, glomerulonephritis, renal immune complex deposits, and serum anti-dsDNA antibody levels, concomitant with the suppression of NFATc1 expression and NLRP3 inflammasome activation, in diseased (NZB × NZW)F1 mice (each P < 0.05 versus controls). Moreover, in mouse and human podocytes, Pim-1 knockdown with targeted small interfering RNA (siRNA) suppressed NFATc1 and NLRP3 inflammasome signaling in the presence of anti-dsDNA-positive serum (each P < 0.05 versus control siRNA). Mechanistically, Pim-1 modulated NLRP3 inflammasome activation through intracellular Ca2+ (P < 0.05 versus normal controls). The therapeutic effect of Pim-1 blockade was replicated in MRL/lpr mice. These data identify Pim-1 as a critical regulator of LN pathogenesis in patients with SLE. Targeting of the Pim-1/NFATc1/NLRP3 pathway might therefore have therapeutic potential in human LN.

Ultraviolet light induces increased T cell activation in lupus-prone mice via type I IFN-dependent inhibition of T regulatory cells

Ultraviolet (UV) light is a known trigger of skin and possibly systemic inflammation in systemic lupus erythematosus (SLE) patients. Although type I interferons (IFN) are upregulated in SLE skin after UV exposure, the mechanisms to explain increased UVB-induced inflammation remain unclear. This paper compares the role of type I IFNs in regulating immune cell activation between wild-type and lupus-prone mice following UVB exposure. 10-week old female lupus-prone (NZM2328), wild-type (BALB/c) and iNZM mice (lack a functional type I IFN receptor on NZM2328 background) were treated on their dorsal skin with 100 mJ/cm2 of UVB for 5 consecutive days. Following UVB treatment, draining lymph node cell populations were characterized via flow cytometry and suppression assays; treated skin was examined for changes in expression of type I IFN genes. Only NZM2328 mice showed an increase in T cell numbers and activation 2 weeks post UVB exposure. This was preceded by a significant increase in UVB-induced type I IFN expression in NZM2328 mice compared to BALB/c mice. Following UVB exposure, both BALB/c and iNZM mice demonstrated an increase in functional T regulatory (TReg) cells; however, this was not seen in NZM2328 mice. These data suggest a skewed UVB-mediated T cell response in lupus-prone mice where activation of T cells is enhanced secondary to a type I IFN-dependent suppression of TReg cells. Thus, we propose type I IFNs are important for UVB-induced inflammation in lupus-prone mice and may be an effective target for prevention of UVB-mediated flares.

Interleukin-23 deficiency alters thymic selection in lupus-prone mice.

We have previously reported that IL-23 receptor deficiency in MRL.lpr mice ameliorates lupus by altering the balance of pro- and anti-inflammatory cytokines in secondary lymphoid organs. As IL-23 may also impact thymic selection, we evaluated the effect of IL-23 on thymic T cell development in lupus-prone mice. We generated IL-23p19-deficient MRL.lpr mice and harvested their thymus at 8 weeks of age. We found that the late stage double negative DN4 population was increased in IL-23p19-/- MRL.lpr mice when compared to IL-23p19+/+ MRL.lpr mice. Despite this, mature thymocytes (CD24-TCRβ+) were decreased by more than 50% in the IL-23p19-deficient mice versus wild-type controls. This was associated with a decrease in the generation of CD8+ T cells, possibly through downregulation of the IL-7 receptor. CD8+ T cells were not only fewer in numbers but also had decreased expression of the migration-related receptors CD44 and CD62L in the thymus and spleens of IL-23p19-deficient versus wild-type mice. We propose that IL-23 promotes the development of lupus-like autoimmunity not only through T cell polarization and cytokine production in the peripheral lymphoid organs but also by influencing T cell thymic development.

Docosahexaenoic Acid (DHA) Suppresses Broad Spectrum of Pathogenic Autoantibodies Elicited in Murine Model of Lupus Flaring (OR12-03-19)

ObjectivesIntranasal instillation of lupus-prone mice with crystalline silica (cSiO2), a respirable particle linked to human lupus, mimics human lupus flaring by accelerating systemic autoimmunity and glomerulonephritis. Notably, these effects were prevented when mouse diets were supplemented with DHA. A broad-spectrum pathogenic autoantibodies (AAs) can be elicited relative to specificity and isotype during human lupus, each of which could differentially contribute to tissue injury. Here, we assessed how DHA influences the autoantibody spectrum over time in this novel preclinical model. MethodsFemale NZBWF1 mice at 6 weeks(wks) of age were fed isocaloric diets AIN-93 G supplemented with DHA a 0, 4, or 10 g/kg diet, beginning either 2 wk before cSiO2 instillation (prevention) or 1 wk after cSiO2 instillation (treatment). For both groups, the mice were intranasally instilled with 1 mg cSiO2 or saline vehicle alone once per wk for 4 wks, starting at 8 wks of age. Cohorts were sacrificed 1, 5, 9, or 13 wks post-instillation (PI) of the last cSiO2 dose. Plasma was subjected to high-throughput AA profiling of different isotypes (IgG, IgM, IgA, and IgE) using a microarray containing 120 autoantigens. ResultscSiO2 triggered production of IgG AAs against components from the cell nucleus (nucleic acids and associated proteins), complement family, cytoplasm, membrane, and matrix proteins within 9 and 13 wk PI A supplementation before and after cSiO2 installation significantly inhibited the IgG AAs production. Importantly, known lupus markers such as anti-DNA, anti-RNP, anti-SM, anti-histone, anti-ds DNA, anti-Ro/SSA, and anti-La/SSB and anti-complement AAs, were inhibited with DHA. Spontaneous elevation of some IgG AAs in plasma, likely genome-driven, was evident at 13 wk in control groups compared to earlier time points. The prevention strategy with DHA showed a more robust effect compared to therapeutic strategy. The preventive effects of DHA treatment on IgM and IgA AAs also mimicked the effect on IgG at 13 wks. ConclusionsOur results highlight a newly identified function of DHA in suppressing production of pathogenic AAs. The data provide preclinical proof of concept for the use of DHA supplementation as an adjunct to established therapeutics for preventing and treating the flaring of lupus and other autoimmune diseases. Funding SourcesNIEHS grant, Lupus Foundation, and Dr. Robert and Carol Diebel Family Endowment.

Functional rare and low frequency variants in BLK and BANK1 contribute to human lupus

Systemic lupus erythematosus (SLE) is the prototypic systemic autoimmune disease. It is thought that many common variant gene loci of weak effect act additively to predispose to common autoimmune diseases, while the contribution of rare variants remains unclear. Here we describe that rare coding variants in lupus-risk genes are present in most SLE patients and healthy controls. We demonstrate the functional consequences of rare and low frequency missense variants in the interacting proteins BLK and BANK1, which are present alone, or in combination, in a substantial proportion of lupus patients. The rare variants found in patients, but not those found exclusively in controls, impair suppression of IRF5 and type-I IFN in human B cell lines and increase pathogenic lymphocytes in lupus-prone mice. Thus, rare gene variants are common in SLE and likely contribute to genetic risk.

IL233, an IL-2-IL-33 hybrid cytokine induces prolonged remission of mouse lupus nephritis by targeting Treg cells as a single therapeutic agent

Lupus glomerulonephritis (GN) is an autoimmune disease characterized by immune complex-deposition, complement activation and glomerular inflammation. In lupus-prone NZM2328 mice, the occurrence of lupus GN was accompanied by a decrease in Treg cells and an increase in proinflammatory cytokine-producing T cells. Because IL-33 in addition to IL-2 has been shown to be important for Treg cell proliferation and ST2 (IL-33 receptor) positive Treg cells are more potent in suppressor activity, a hybrid cytokine with active domains of IL-2 and IL-33 was generated to target the ST2+ Treg cells as a therapeutic agent to treat lupus GN. Three mouse models were used: spontaneous and Ad-IFNα- accelerated lupus GN in NZM2328 and the lymphoproliferative autoimmune GN in MRL/lpr mice. Daily injections of IL233 for 5 days prevented Ad-IFNα-induced lupus GN and induced remission of spontaneous lupus GN. The remission was permanent in that no relapses were detected. The remission was accompanied by persistent elevation of Treg cells in the renal lymph nodes. IL233 is more potent than IL-2 and IL-33 either singly or in combination in the treatment of lupus GN. The results of this study support the thesis that IL233 should be considered as a novel agent for treating lupus GN.

Patterns of ANA+ B cells for SLE patient stratification.

IgG antinuclear antibodies (ANAs) are a dominant feature of several autoimmune diseases. We previously showed that systemic lupus erythematosus (SLE) is characterized by increased ANA+ IgG plasmablasts/plasma cells (PCs) through aberrant IgG PC differentiation rather than an antigen-specific tolerance defect. Here, we aimed to understand the differentiation pathways resulting in ANA+ IgG PCs in SLE patients. We demonstrate distinct profiles of ANA+ antigen-experienced B cells in SLE patients, characterized by either a high frequency of PCs or a high frequency of IgG+ memory B cells. This classification of SLE patients was unrelated to disease activity and remained stable over time in almost all patients, suggesting minimal influence of disease activity. A similar classification applies to antigen-specific B cell subsets in mice following primary immunization with T-independent and T-dependent antigens as well as in lupus-prone mouse models (MRL/lpr and NZB/W). We further show that, in both lupus-prone mice and SLE patients, the classification correlates with the serum autoantibody profile. In this study, we identified B cell phenotypes that we propose reflect an extrafollicular pathway for PC differentiation or a germinal center pathway, respectively. The classification we propose can be used to stratify patients for longitudinal studies and clinical trials.

Systemic activation of B and CD4 but not CD8 cells drives early disease in lupus prone mice, while macrophages, CD4 and CD8 cells infiltrate the kidney with the exclusion of B cells

Abstract Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the presence of autoantibodies in serum and multi-organ inflammation. Immune complex deposition in kidney can lead to lupus nephritis, which is a major risk factor for morbidity and mortality in SLE. Using FcγRIIB−/− mice as a lupus animal model, we performed a detailed time course analysis of the extent of the spontaneous leukocyte activation and expansion in spleen and in renal, inguinal, mesenteric lymph nodes. We then correlated the data with the onset of pathology and leukocyte infiltration in the kidney. In the FcγRIIB−/− mouse model, effector-memory CD4 cells and germinal centers appeared first in the spleen and renal lymph nodes, but not in other immune organs such as inguinal or mesenteric lymph nodes. As the disease progresses in these mice, lymphocytes undergo an extensive expansion that involves all immune organs in a systemic manner. At the same moment we can detect the first signs of kidney pathology, measured by histopathology and by the levels of creatinine and albumin in urine. In FcγRIIB−/− mice, the onset of kidney pathology correlates with leukocyte infiltration in kidney, detected both by parenchyma-restricted flow cytometry and histopathology. Macrophages, CD4 and CD8 cells are found both in glomerular and interstitial spaces with the exclusion of B cells, most likely suggesting a role for T cells and/or macrophage specific chemokine signals in lupus nephritic kidney.

Rab4A inactivation in T cells blocks mTOR activation, pro-inflammatory lineage development, and disease pathogenesis in lupus-prone mice

Abstract Introduction Expression of Rab4A is increased in T cells of patients and mice with SLE. Overexpression of Rab4A forms a positive feedback loop with mTOR that can be blocked with therapeutic efficacy in SLE. To determine the impact of this gene on disease development, the triple-congenic lupus-prone Sle1.2.3 mouse strain (TC) have been backcrossed with C57Bl/6 wild-type (WT) mice that carry floxed Rab4AQ72L (TC-FL) alleles or lack Rab4A in T cells (TC-KO). Methods Proteinuria was assessed by the Bradford assay. Splenocytes were examined by flow cytometry. Autoantibody production was measured by ELISA. Results TC mice had increased proteinuria over age and sex-matched WT controls. Deletion of Rab4A in T cells reduced proteinuria ≥ 50% in female TC-KO mice relative to TC-FL mice at 21 or 40 weeks of age. Similar trends were noted in male mice. The production of antinuclear and antiphospholipid antibodies was reduced in TC-KO mice as compared to TC-FL and parental TC controls. Immunophenotyping unveiled a 45% depletion of CD4+ T cells and 50% expansion of CD8+ T cells in female TC-KO mice relative to TC-FL controls. CD38 expression was reduced on CD4+ T cells of TC-KO mice by 51% and 48% relative to TC and TC-FL controls. CD38 expression was also reduced on CD8+ T cells but not on CD19+ B cells. mTORC1 activity was reduced by 36% in CD4 T cells, but not in CD8 T cells or B cells of TC-KO mice. Along these lines, overexpression of Rab4A activated mTORC1, reduced expression of CD4, and increased expression of CD38 in Jurkat cells. Conclusion These findings reveal an opposite influence of Rab4A on endosomal recycling of CD4 and CD38 that facilitates mTORC1 activation and thus causes pro-inflammatory T-cell lineage specification and triggers autoimmunity in SLE.

Angiotensin-converting enzyme inhibitor suppresses Type I interferon responses, decreases neuroinflammation and improves depression-like behavior in MRL/lpr lupusprone mice

Abstract Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by multi-organ damage. Interferon- α (IFN-α) is a central mediator in disease pathogenesis. Neuropsychiatric lupus (NPSLE) is one of the most common manifestations of human SLE often causing depression. Administration of IFN-α in patients with chronic viral infections or cancers causes depressive symptoms. Angiotensin-converting enzyme (ACE) is part of the kallikrein-kinin/renin-angiotensin (KKS/RAS) system that regulates many physiological processes, including inflammation and brain functions. It is known that ACE degrades bradykinin into inactive peptides. We have previously shown in an in vitro model of mouse bone-marrow-derived dendritic cells that the effects of captopril (an ACE inhibitor) on IFN responsive gene inhibition were reversed when bradykinin receptors were blocked, suggesting that ACE, in part, acts via kinin receptors to bring about the suppressive effects. We used the MRL/lpr lupus-prone mouse model, an established model to study NPSLE, to check the in vivo effects of captopril on IFN-induced immune responses, neuroinflammation, and behavior. Exposing MRL/lpr mice to IFN-α increased depressive-like behavior and enhanced ACE expression in the brain. Administering captopril in MRL/lpr mice decreased expression of IFN responsive genes in brain and kidney, decreased microglial activation (IBA1 expression) and reduced depressive-like behavior as assessed by the forced swim test. Thus, ACE inhibitors may have potential for therapeutic use for systemic and neurolupus.

Targeting T cell activation and lupus autoimmune phenotypes with a novel glucose transporter inhibitor

Abstract CD4+ T cells have numerous features of over-activated cellular metabolism in lupus patients and mouse models of the disease, including a higher glycolysis. We have previously shown that treatment of lupus-prone mice with 2-deoxy-D-glucose, which inhibits the first step of glycolysis, was sufficient to prevent autoimmune activation. Because 2DG has potential off-target effects, we sought to directly inhibit glycolysis by blocking glucose transporters. Here, we show that CG-5, a novel glucose transporter inhibitor, ameliorated lupus-like symptoms in a spontaneous lupus-prone mouse model, B6.NZM2410.Sle1.Sle2.Sle3 (Triple-congenic, TC), and in a chronic graft-versus-host-disease (cGVHD) model of induced lupus. Moreover, CG-5 treatment reduced lupus phenotypes including the expansion of germinal center B cells, as well as the production of autoantibodies in both TC mice and cGVHD models. In vitro, CG-5 blocked glycolysis in CD4+ T cells, and limited the expansion of CD4+ T cells induced by alloreactive stimulation. CG-5 also modulated CD4+ T cell polarization by inhibiting Th1 and Th17 differentiation and promoting regulatory T (Treg) induction. Finally, CG-5 blocked glycolysis in human T cells. Overall, our data suggest that blocking glucose uptake with a small molecule inhibitor ameliorates the symptoms of lupus, at least partially due to its inhibition of glycolysis in CD4+ T cells. Supported by grants from the NIH (RO1 AI128901) and the Lupus Research Alliance (LRA-TIL 416522) to LM, and by an Experimental Pathology Innovative Grant from the Department of Pathology, Immunology and Laboratory Medicine, University of Florida to WL.

Evaluating the role of candidate gene, csf3r, for sex-linked susceptibility to lupus-like disease in mice

Abstract Systemic lupus erythematosus (SLE) is an autoimmune disorder that primarily affects women and this trend is also observed in BWF1 lupus-prone mice. Although the factors that contribute to sex-specific lupus incidence are complex, evidence suggests that sex hormone regulation of genetic targets likely play a role. Several candidate genes have been identified by their disproportionate expression within splenocytes isolated from male and female BWF1 mice and because their expression is regulated by the sex hormone, testosterone. One candidate gene in particular, csf3-r, is predominantly expressed in CD11b+ cells and is the focus of our current studies. Previous research has indicated that Gr1low CD11b+ cells accumulate in male lupus-prone mice, and are associated with disease suppression. We hypothesize that sex-specific expression of csf3-r contributes to the different frequencies of specific neutrophil subpopulations in BWF1 lupus prone mice and may contribute to disease protection in male mice. To test this hypothesis, we are examining the expression levels of csf3r in neutrophils in lupus-prone and nonautoimmune-prone male and female mice and assessing potential correlations between sex-specific expression of csf3r and the frequencies of particular neutrophil subpopulations. The elucidation of testosterone-regulated pathways that contribute to lupus-like disease may point to new therapies that may be beneficial in autoimmune diseases with sex-specific incidences.

Induction of Regulatory B Cells by Bacterial DNA in the Gut Microbiota at Early Age is Beneficial in Lupus-prone Mice

Abstract SLE is a complex autoimmune disorder with no known cure. We previously reported that oral vancomycin treatment of female MRL/lpr mice during active disease (9 to 15 weeks of age) could significantly ameliorate disease symptoms. However, when vancomycin treatment was initiated from an earlier age (from 3 to 15 weeks), the beneficial effect was not observed. Strikingly, mice given vancomycin during the pre-disease stage (from 3 to 8 weeks) exhibited exacerbated lupus disease. As vancomycin works by removing parts of the gut microbiota, we hypothesized that the regulatory immunity induced by gut microbiota at early age is essential in hammering lupus disease development in MRL/lpr mice. To test the hypothesis, we analyzed diverse regulatory cell types from the mice receiving vancomycin from 3 to 8 weeks of age. Regulatory B (Breg) cells, in particular, were found to be reduced in both the percentage and absolute number in multiple lymphoid organs. Importantly, adoptive transfer of Breg cells at 6–7 weeks of age to long-term vancomycin-treated mice improved lupus-like symptoms. This clearly indicates that Breg cells, inducible by vancomycin-sensitive gut microbiota, plays an important role in suppressing lupus disease initiation and progression. We next sought to determine Breg inducers in the gut microbiota. The serum level of bacterial DNA was found to be significantly lower in mice treated with vancomycin. More importantly, early administration of bacterial DNA reproduced the beneficial effect seen in the Breg adoptive transfer experiment. Together, these results suggest an important protective mechanism against lupus initiation that involves bacterial DNA in the gut microbiota and the induction of Breg cells.

A single infection with a malaria parasite protects mice from lethal autoimmune glomerulonephritis

Abstract The progression of autoimmune diseases such as Systemic Lupus Erythematous (SLE) can be altered by environmental factors, including parasitic infections. Epidemiological studies have shown a relative absence of SLE in West Africa (areas of endemic malaria), even though SLE is highly prevalent in populations of African descent living outside of Africa. We hypothesize that malaria infections might reduce the incidence of lupus. In the present work, we assess the effect of the non-lethal Plasmodium yoelii 17XNL in a well-characterized animal model of SLE (FcγRIIB−/−). Mice deficient in the inhibitory Fc receptor for IgG (FcγRIIB) develop spontaneous disease driven by the production of anti-nuclear autoantibodies, a broad immune activation, splenomegaly, anemia and lethal glomerulonephritis with a pathology similar to human SLE. We infected FcγRIIB−/− mice at 2 months of age with P. yoelii and followed the progression of autoimmune disease for 5 months. Infection with P. yoelii increased the titer of a broad range of autoantibodies, with concomitant immune-complex deposition and complement fixation in the kidney. While lupus-prone mice succumbed from renal disease detected by protein in urine, malaria-infected lupus-prone mice did not develop proteinuria or lethal disease. Infection with the parasite did not alter tolerance mechanisms leading to lupus but instead prevented end-point tissue pathology. P. yoelii infection seems to inhibit pathogenic leukocyte infiltration without affecting the autoimmune inflammation of glomeruli. These results indicate a possible route for lupus protection that specifically targets renal function, which remains a cause of the substantial morbidity and mortality in SLE patients.

Sh3bp2 Gain-Of-Function Mutation Ameliorates Lupus Phenotypes in B6.MRL-Faslpr Mice.

SH3 domain-binding protein 2 (SH3BP2) is an adaptor protein that is predominantly expressed in immune cells, and it regulates intracellular signaling. We had previously reported that a gain-of-function mutation in SH3BP2 exacerbates inflammation and bone loss in murine arthritis models. Here, we explored the involvement of SH3BP2 in a lupus model. Sh3bp2 gain-of-function (P416R knock-in; Sh3bp2KI/+) mice and lupus-prone B6.MRL-Faslpr mice were crossed to yield double-mutant (Sh3bp2KI/+Faslpr/lpr) mice. We monitored survival rates and proteinuria up to 48 weeks of age and assessed renal damage and serum anti-double-stranded DNA antibody levels. Additionally, we analyzed B and T cell subsets in lymphoid tissues by flow cytometry and determined the expression of apoptosis-related molecules in lymph nodes. Sh3bp2 gain-of-function mutation alleviated the poor survival rate, proteinuria, and glomerulosclerosis and significantly reduced serum anti-dsDNA antibody levels in Sh3bp2KI/+Faslpr/lpr mice. Additionally, B220+CD4−CD8− T cell population in lymph nodes was decreased in Sh3bp2KI/+Faslpr/lpr mice, which is possibly associated with the observed increase in cleaved caspase-3 and tumor necrosis factor levels. Sh3bp2 gain-of-function mutation ameliorated clinical and immunological phenotypes in lupus-prone mice. Our findings offer better insight into the unique immunopathological roles of SH3BP2 in autoimmune diseases.

084 UVB induces prolonged T cell activation in lupus-prone mice via type I IFN inhibition of T regulatory cells

Many patients with systemic lupus erythematosus (SLE) are photosensitive, which is characterized by the development of systemic and cutaneous symptoms following minimal sun exposure. While type I IFNs are increased in SLE skin after ultraviolet light (UV) exposure, the mechanisms to explain photosensitivity remain unclear. In-depth mechanistic studies conducted in wild-type mice show induction of a suppressive immune response to UVB, but how this applies to lupus-prone mice is unknown. This study explores the question of how activation of the adaptive immune system differs between wild-type mice vs. lupus-prone mice following UVB exposure, and how type I IFNs contribute to this difference. In order to examine UVB responses, 10-week old female lupus-prone (NZM2328), wild-type (BALB/c) and iNZM mice (lack type I IFN receptor on NZM background) were treated on their dorsal skin with 100mJ/cm2 of UVB for 5 consecutive days. No differences in the skin injury process (skin thickness) were noted between the mouse strains. Notably, however, only the NZM2328 mice showed an increase in draining lymph node size and T cell activation 2 weeks post UVB exposure. Both BALB/c and iNZM mice demonstrated an increase in functional T regulatory (Treg) cells 2 weeks post UVB treatment; this was not seen in NZM2328 mice. These data suggest that sustained UVB-mediated T cell activation is increased in lupus-prone mice in a type I IFN-dependent fashion through suppression of Tregs. Thus, we propose type I IFNs are important to the photosensitive responses in lupus and suggest that targeting type I IFNs could offer potential as a preventative treatment for UVB induced lupus flares.

Targeting T Cell Activation and Lupus Autoimmune Phenotypes by Inhibiting Glucose Transporters.

CD4+ T cells have numerous features of over-activated cellular metabolism in lupus patients and mouse models of the disease. This includes a higher glycolysis than in healthy controls. Glucose transporters play an essential role in glucose metabolism by controlling glucose import into the cell from the extracellular environment. We have previously shown that treatment of lupus-prone mice with 2-deoxy-D-glucose, which inhibits the first step of glycolysis was sufficient to prevent autoimmune activation. However, direct targeting of glucose transporters has never been tested in a mouse model of lupus. Here, we show that CG-5, a novel glucose transporter inhibitor, ameliorated autoimmune phenotypes in a spontaneous lupus-prone mouse model, B6.NZM2410.Sle1.Sle2.Sle3 (Triple-congenic, TC), and in a chronic graft- vs. host-disease (cGVHD) model of induced lupus. In vitro, CG-5 blocked glycolysis in CD4+ T cells, and limited the expansion of CD4+ T cells induced by alloreactive stimulation. CG-5 also modulated CD4+ T cell polarization by inhibiting Th1 and Th17 differentiation and promoting regulatory T (Treg) induction. Moreover, CG-5 treatment reduced lupus phenotypes including the expansion of germinal center B (GC B) cells, as well as the production of autoantibodies in both TC mice and cGVHD models. Finally, CG-5 blocked glycolysis in human T cells. Overall, our data suggest that blocking glucose uptake with a small molecule inhibitor ameliorates autoimmune activation, at least partially due to its inhibition of glycolysis in CD4+ T cells.

Slamming the brakes on lupus with CAR T cells.

Sustained depletion of B cells with CAR T cells induces disease remission in lupus-prone mice.