Murine Lupus Models Research Articles

CD21 blockade is protective against neurological symptoms in a murine model of lupus

CD21 blockade is protective against neurological symptoms in a murine model of lupus

SERPINB3 Delays Glomerulonephritis and Attenuates the Lupus-Like Disease in Lupus Murine Models by Inducing a More Tolerogenic Immune Phenotype.

Objective: To explore the effects of SERPINB3 administration in murine lupus models with a focus on lupus-like nephritis.Methods: 40 NZB/W F1 mice were subdivided into 4 groups and intraperitoneally injected with recombinant SERPINB3 (7.5 μg/0.1 mL or 15 μg/0.1 mL) or PBS (0.1 mL) before (group 1 and 2) or after (group 3 and 4) the development of proteinuria (≥100 mg/dl). Two additional mice groups were provided by including 20 MRL/lpr mice which were prophylactically injected with SERPINB3 (10 mice, group 5) or PBS (10 mice, group 6). Time of occurrence and levels of anti-dsDNA and anti-C1q antibodies, proteinuria and serum creatinine, overall- and proteinuria-free survival were assessed in mice followed up to natural death. Histological analysis was performed in kidneys of both lupus models. The Th17:Treg cell ratio was assessed by flow-cytometry in splenocytes of treated and untreated MRL/lpr mice. Statistical analysis was performed using non parametric tests and Kaplan-Meier curves, when indicated.Results: Autoantibody levels and proteinuria were significantly decreased and time of occurrence significantly delayed in SERPINB3-treated mice vs. controls. In agreement with these findings, proteinuria-free and overall survival were significantly improved in SERPINB3-treated groups vs. controls. Histological analysis demonstrated a lower prevalence of severe tubular lesions in kidneys of group 5 vs. group 6. SERPINB3-treated mice showed an overall trend toward a reduced prevalence of severe lesions in both strains. Th17:Treg ratio was significantly decreased in splenocytes of MRL/lpr mice treated with SERPINB3, compared to untreated control mice.Conclusions: SERPINB3 significantly improves disease course and delays the onset of severe glomerulonephritis in lupus-prone mice, possibly inducing a more tolerogenic immune phenotype.

Administration of activated lymphocyte-derived DNA accelerates and aggravates lupus nephritis in B6/lpr mice: a new approach to modify a lupus murine model.

B6/lpr mouse strain is a well-known systemic lupus erythematosus murine model characterized by uncontrolled lymphoproliferation and autoantibody production. However, it displays a delayed and mild development of lupus nephritis (LN), which is not conducive to the research of the pathogenesis and therapeutic strategies of this condition. Our previous study demonstrated that activated lymphocyte-derived DNA (ALD-DNA) could induce high urine protein levels and severe glomerulonephritis (GN) in BALB/c mice. In the present study, we tried to remedy delayed urine protein production and mild GN in B6/lpr mice via ALD-DNA immunization. We found that urine protein levels were enhanced significantly in B6/lpr mice 4weeks after ALD-DNA immunization compared with those in unactivated lymphocyte-derived (UnALD)-DNA- and phosphate-buffered saline (PBS)-treated controls. Moreover, more serious GN and glomerular immune complex were observed in ALD-DNA-immunized B6/lpr mice. We further explored the mechanism, and found that ALD-DNA immunization promoted T helper type 17 (Th17) cell enrichment remarkably, which enhanced the proportion of autoantibody-secreting plasma cells and promoted the production of anti-dsDNA autoantibodies, leading to accelerated and aggravated LN. Our data demonstrated that ALD-DNA immunization could remedy delayed urine protein production and mild GN in B6/lpr mouse, which makes it more suitable for studies on the pathogenesis of and therapeutic strategies against LN.

Role of Lgals9 Deficiency in Attenuating Nephritis and Arthritis in BALB/c Mice in a Pristane-Induced Lupus Model.

In systemic lupus erythematosus (SLE), an autoimmune disease associated with multiple organ involvement, the development of lupus nephritis determines prognosis, and arthritis impairs quality of life. Galectin 9 (Gal-9, Lgals9) is a β-galactoside-binding lectin that has been used for clinical application in autoimmune diseases, since recombinant Gal-9, as a ligand for T cell immunoglobulin and mucin domain-containing protein 3 (TIM-3), induces apoptosis of activated CD4+TIM-3+ Th1 cells. This study was undertaken to investigate whether deficiency of Lgals9 has beneficial or deleterious effects on lupus in a murine model. Gal-9+/+ and Gal-9-/- female BALB/c mice were injected with pristane, and the severity of arthritis, proteinuria, and levels of autoantibody production were assessed at several time points immediately following injection. At 7 months after pristane injection, renal pathologic features, the severity of joint inflammation, and formation of lipogranulomas were evaluated. Subsets of inflammatory cells in the spleen and peritoneal lavage were characterized, and expression levels of cytokines from peritoneal macrophages were analyzed. Lgals9 deficiency protected against the development of immune complex glomerulonephritis, arthritis, and peritoneal lipogranuloma formation in BALB/c mice in this murine model of pristane-induced lupus. The populations of T cell subsets and B cells in the spleen and peritoneum were not altered by Lgals9 deficiency in pristane-injected BALB/c mice. Furthermore, Lgals9 deficiency protected against pristane-induced lupus without altering the Toll-like receptor 7-type I interferon pathway. Gal-9 is required for the induction and development of lupus nephritis and arthritis in this murine model of SLE. The results of the current investigation provide a potential new strategy in which antagonism of Gal-9 may be beneficial for the treatment of nephritis and arthritis in patients with SLE through targeting of activated macrophages.

Modulation of TLR2/1 by PAM3CSK4 to induce generation of immunosuppressive macrophages as a therapeutic approach for SLE

Abstract Systematic Lupus Erythematosus (SLE) is an autoimmune disease characterized by the overproduction of autoantibodies and the chronic inflammation of multiple organs. Early studies suggested that T and/or B cell abnormalities were critical to disease pathogenesis in lupus patients. More recent work shows that abnormalities in the innate immunity play a contributory if not central role. In that context, we find that SLE patients have significantly more CD14lowCD16+ monocytes compared to healthy controls.CD14lowCD16+ monocytes are a subset known as non-classical monocytes and display inflammatory characteristics upon activation. The frequency of inflammatory macrophages correlates with disease severity and is associated with reduced clearance of apoptotic cells and the overproduction of inflammatory cytokines. We previously found that the TLR2/1 agonist PAM3CSK4 (PAM3) can inhibit the generation of M1- while promoting the generation of immunosuppressive M2-like macrophages. This work examines whether PAM3 can shift the M1:M2 macrophage ratio to restore balance in lupus patients. Even though phenotypically, PAM3 did not seem to induce as many as CD163+ (a functional marker of M2) macrophages like M-CSF did, there was no significant difference in the endocytosis ability of the CD163+ macrophages induced by PAM3 compared M-CSF induced ones. The in vivo activity of PAM3 was investigated in the NZB/W murine model of lupus. Preliminary results indicate that, PAM3 injection increases the survival and decreases proteinuria in mice sera. These findings suggest that PAM3 may promote the polarization of SLE monocytes into immunosuppressive macrophages and thus could represent a novel approach to the therapy of this autoimmune disease.

An upregulation of TLR7 in renal dendritic cells is associated with glomerulonephritis across multiple B6. Sle1-associated strains.

Abstract Toll-like receptors (TLRs) 7 and 9 are important innate signalling molecules with opposing roles in the development and progression of Systemic Lupus Erythematosus (SLE). While multiple studies support a dependency on TLR7 for disease development, genetic ablation of TLR9 results in severe disease with glomerulonephritis (GN) by a largely unknown mechanism. In the present study we show that the autoimmune phenotypes exhibited by TLR9-deficient Sle1 mice (Sle1TLR9−/−) mice are akin to those shown by the Sle1Tg7 strain, a model with a 2-fold increase in TLR7 expression. These include increased autoantibody titers, systemic immune activation and glomerulonephritis (GN). Kidney disease in Sle1TLR9−/− mice is associated with an increase in renal CD11b+CD11c+MHC+F480− dendritic cells (DC). These cDCs have higher levels of TLR7 protein with a corresponding increased ability to stimulate T cell proliferation following R848 exposure. Our analyses of TLR7 using flow cytometry in the Sle1Tg7 and Sle123 murine lupus models indicated similar increases in protein expression within cDCs, suggesting their importance across multiple model systems. Genetic ablation of TLR9 in Sle1 mice also resulted in increased TLR7-reactive RNA/anti-RNA-associated autoantibodies, indicating that TLR9 is required for B cell tolerance to RNA-associated antigens. In summary, the increase in TLR7-reactive immune complexes (IC) and the concomitant enhanced expression of their receptor, promotes Inflammation and Disease in Sle1TLR9−/− mice.

Galectin-9 inhibits TLR7-mediated autoimmunity in murine lupus models.

Uncontrolled secretion of type I IFN, as the result of endosomal TLR (i.e., TLR7 and TLR9) signaling in plasmacytoid DCs (pDCs), and abnormal production of autoantibodies by B cells are critical for systemic lupus erythematosus (SLE) pathogenesis. The importance of galectin-9 (Gal-9) in regulating various autoimmune diseases, including lupus, has been demonstrated. However, the precise mechanism by which Gal-9 mediates this effect remains unclear. Here, using spontaneous murine models of lupus (i.e., BXSB/MpJ and NZB/W F1 mice), we demonstrate that administration of Gal-9 results in reduced TLR7-mediated autoimmune manifestations. While investigating the mechanism underlying this phenomenon, we observed that Gal-9 inhibits the phenotypic maturation of pDCs and B cells and abrogates their ability to mount cytokine responses to TLR7/TLR9 ligands. Importantly, immunocomplex-mediated (IC-mediated) and neutrophil extracellular trap-mediated (NET-mediated) pDC activation was inhibited by Gal-9. Additionally, the mTOR/p70S6K pathway, which is recruited by both pDCs and B cells for TLR-mediated IFN secretion and autoantibody generation, respectively, was attenuated. Gal-9 was found to exert its inhibitory effect on both the cells by interacting with CD44.

CD38 promotes pristane-induced chronic inflammation and increases susceptibility to experimental lupus by an apoptosis-driven and TRPM2-dependent mechanism

In this study, we investigated the role of CD38 in a pristane-induced murine model of lupus. CD38-deficient (Cd38−/−) but not ART2-deficient (Art2−/−) mice developed less severe lupus compared to wild type (WT) mice, and their protective phenotype consisted of (i) decreased IFN-I-stimulated gene expression, (ii) decreased numbers of peritoneal CCR2hiLy6Chi inflammatory monocytes, TNF-α-producing Ly6G+ neutrophils and Ly6Clo monocytes/macrophages, (iii) decreased production of anti-single-stranded DNA and anti-nRNP autoantibodies, and (iv) ameliorated glomerulonephritis. Cd38−/− pristane-elicited peritoneal exudate cells had defective CCL2 and TNF-α secretion following TLR7 stimulation. However, Tnf-α and Cxcl12 gene expression in Cd38−/− bone marrow (BM) cells was intact, suggesting a CD38-independent TLR7/TNF-α/CXCL12 axis in the BM. Chemotactic responses of Cd38−/− Ly6Chi monocytes and Ly6G+ neutrophils were not impaired. However, Cd38−/− Ly6Chi monocytes and Ly6Clo monocytes/macrophages had defective apoptosis-mediated cell death. Importantly, mice lacking the cation channel TRPM2 (Trpm2−/−) exhibited very similar protection, with decreased numbers of PECs, and apoptotic Ly6Chi monocytes and Ly6Clo monocytes/macrophages compared to WT mice. These findings reveal a new role for CD38 in promoting aberrant inflammation and lupus-like autoimmunity via an apoptosis-driven mechanism. Furthermore, given the implications of CD38 in the activation of TRPM2, our data suggest that CD38 modulation of pristane-induced apoptosis is TRPM2-dependent.

Gut Microbiota in Human Systemic Lupus Erythematosus and a Mouse Model of Lupus.

Gut microbiota dysbiosis has been observed in a number of autoimmune diseases. However, the role of the gut microbiota in systemic lupus erythematosus (SLE), a prototypical autoimmune disease characterized by persistent inflammation in multiple organs of the body, remains elusive. Here we report the dynamics of the gut microbiota in a murine lupus model, NZB/W F1, as well as intestinal dysbiosis in a small group of SLE patients with active disease. The composition of the gut microbiota changed markedly before and after the onset of lupus disease in NZB/W F1 mice, with greater diversity and increased representation of several bacterial species as lupus progressed from the predisease stage to the diseased stage. However, we did not control for age and the cage effect. Using dexamethasone as an intervention to treat SLE-like signs, we also found that a greater abundance of a group of lactobacilli (for which a species assignment could not be made) in the gut microbiota might be correlated with more severe disease in NZB/W F1 mice. Results of the human study suggest that, compared to control subjects without immune-mediated diseases, SLE patients with active lupus disease possessed an altered gut microbiota that differed in several particular bacterial species (within the genera Odoribacter and Blautia and an unnamed genus in the family Rikenellaceae) and was less diverse, with increased representation of Gram-negative bacteria. The Firmicutes/Bacteroidetes ratios did not differ between the SLE microbiota and the non-SLE microbiota in our human cohort.IMPORTANCE SLE is a complex autoimmune disease with no known cure. Dysbiosis of the gut microbiota has been reported for both mice and humans with SLE. In this emerging field, however, more studies are required to delineate the roles of the gut microbiota in different lupus-prone mouse models and people with diverse manifestations of SLE. Here, we report changes in the gut microbiota in NZB/W F1 lupus-prone mice and a group of SLE patients with active disease.

Bruton's Tyrosine Kinase, a Component of B Cell Signaling Pathways, Has Multiple Roles in the Pathogenesis of Lupus.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the loss of adaptive immune tolerance to nucleic acid-containing antigens. The resulting autoantibodies form immune complexes that promote inflammation and tissue damage. Defining the signals that drive pathogenic autoantibody production is an important step in the development of more targeted therapeutic approaches for lupus, which is currently treated primarily with non-specific immunosuppression. Here, we review the contribution of Bruton’s tyrosine kinase (Btk), a component of B and myeloid cell signaling pathways, to disease in murine lupus models. Both gain- and loss-of-function genetic studies have revealed that Btk plays multiple roles in the production of autoantibodies. These include promoting the activation, plasma cell differentiation, and class switching of autoreactive B cells. Small molecule inhibitors of Btk are effective at reducing autoantibody levels, B cell activation, and kidney damage in several lupus models. These studies suggest that Btk may promote end-organ damage both by facilitating the production of autoantibodies and by mediating the inflammatory response of myeloid cells to these immune complexes. While Btk has not been associated with SLE in GWAS studies, SLE B cells display signaling defects in components both upstream and downstream of Btk consistent with enhanced activation of Btk signaling pathways. Taken together, these observations indicate that limiting Btk activity is critical for maintaining B cell tolerance and preventing the development of autoimmune disease. Btk inhibitors, generally well-tolerated and approved to treat B cell malignancy, may thus be a useful therapeutic approach for SLE.

B Cell-Intrinsic Role for IRF5 in TLR9/BCR-Induced Human B Cell Activation, Proliferation, and Plasmablast Differentiation.

Upon recognition of antigen, B cells undergo rapid proliferation followed by differentiation to specialized antibody secreting cells (ASCs). During this transition, B cells are reliant upon a multilayer transcription factor network to achieve a dramatic remodeling of the B cell transcriptional landscape. Increased levels of ASCs are often seen in autoimmune diseases and it is believed that altered expression of regulatory transcription factors play a role in this imbalance. The transcription factor interferon regulatory factor 5 (IRF5) is one such candidate as polymorphisms in IRF5 associate with risk of numerous autoimmune diseases and correlate with elevated IRF5 expression. IRF5 genetic risk has been widely replicated in systemic lupus erythematosus (SLE), and loss of Irf5 ameliorates disease in murine lupus models, in part, through the lack of pathogenic autoantibody secretion. It remains unclear, however, whether IRF5 is contributing to autoantibody production through a B cell-intrinsic function. To date, IRF5 function in healthy human B cells has not been characterized. Using human primary naive B cells, we define a critical intrinsic role for IRF5 in B cell activation, proliferation, and plasmablast differentiation. Targeted IRF5 knockdown resulted in significant immunoglobulin (Ig) D retention, reduced proliferation, plasmablast differentiation, and IgG secretion. The observed decreases were due to impaired B cell activation and clonal expansion. Distinct from murine studies, we identify and confirm new IRF5 target genes, IRF4, ERK1, and MYC, and pathways that mediate IRF5 B cell-intrinsic function. Together, these results identify IRF5 as an early regulator of human B cell activation and provide the first dataset in human primary B cells to map IRF5 dysfunction in SLE.

Comparative gene expression profiles in healthy and autoimmune mice

Comparative gene expression profiles in healthy and autoimmune mice

Comparative gene expression profiles in healthy and autoimmune mice

Comparative gene expression profiles in healthy and autoimmune mice

Defective Suppressor of Cytokine Signaling 1 Signaling Contributes to the Pathogenesis of Systemic Lupus Erythematosus.

Systemic lupus erythematosus (SLE) is a complex autoimmune disease involving injuries in multiple organs and systems. Exaggerated inflammatory responses are characterized as end-organ damage in patients with SLE. Although the explicit pathogenesis of SLE remains unclear, increasing evidence suggests that dysregulation of cytokine signals contributes to the progression of SLE through the Janus kinase/signal transducer and activator of transcription (STAT) signaling pathway. Activated STAT proteins translocate to the cell nucleus and induce transcription of target genes, which regulate downstream cytokine production and inflammatory cell infiltration. The suppressor of cytokine signaling 1 (SOCS1) is considered as a classical inhibitor of cytokine signaling. Recent studies have demonstrated that SOCS1 expression is decreased in patients with SLE and in murine lupus models, and this negatively correlates with the magnitude of inflammation. Dysregulation of SOCS1 signals participates in various pathological processes of SLE such as hematologic abnormalities and autoantibody generation. Lupus nephritis is one of the most serious complications of SLE, and it correlates with suppressed SOCS1 signals in renal tissues. Moreover, SOCS1 insufficiency affects the function of several other organs, including skin, central nervous system, liver, and lungs. Therefore, SOCS1 aberrancy contributes to the development of both systemic and local inflammation in SLE patients. In this review, we discuss recent studies regarding the roles of SOCS1 in the pathogenesis of SLE and its therapeutic implications.

The roles and applications of autoantibodies in progression, diagnosis, treatment and prognosis of human malignant tumours.

The existence of autoantibodies towards an individual's own proteins or nucleic acids has been established for more than 100years, and for a long period, these autoantibodies have been believed to be closely associated with autoimmune diseases. However, in recent years, researchers have become more interested in the role and application of autoantibodies in progression, diagnosis, treatment and prognosis of human malignant tumours. Over the past few decades, numerous epidemiological studies have shown that the risk of certain cancers is significantly altered (increased or decreased) in patients with autoimmune diseases, which suggests that autoantibodies may play either promoting or suppressing roles in cancer progression. The idea that autoantibodies are directly involved in tumour progression gains special support by the findings that some antibodies secreted by a variety of cancer cells can promote their proliferation and metastasis. Because the cancer cells generate cell antigenic changes (neoantigens), which trigger the immune system to produce autoantibodies, serum autoantibodies against tumour-associated antigens have been established as a novel type of cancer biomarkers and have been extensively studied in different types of cancer. The autoantibodies as biomarkers in cancer diagnosis are not only more sensitive and specific than antigens, but also could appear before clinical evidences of the tumours, thus disclosing them. The observations that cancer risk is lower in patients with some autoimmune diseases suggest that certain autoantibodies may be protective from certain cancers. Moreover, the presence of autoantibodies in healthy individuals implies that it could be safe to employ autoantibodies to treat cancer. Of note, an autoantibodies derived from lupus murine model received much attention due to their selective cytotoxicity for malignant tumour cell without harming normal ones. These studies showed the therapeutic value of autoantibodies in cancer. In this review, we revisited the pathological or protective role of autoantibodies in cancer progression, summarize the application of autoantibodies in cancer diagnosis and prognosis, and discuss the value of autoantibodies in cancer therapy. The studies established to date suggest that autoantibodies not only regulate cancer progression but also promise to be valuable instruments in oncological diagnosis and therapy.

Neutrophils Slow Disease Progression in Murine Lupus via Modulation of Autoreactive Germinal Centers.

Neutrophils are well characterized as mediators of peripheral tissue damage in lupus, but it remains unclear whether they influence loss of self-tolerance in the adaptive immune compartment. Lupus neutrophils produce elevated levels of factors known to fuel autoantibody production, including IL-6 and B cell survival factors, but also reactive oxygen intermediates, which can suppress lymphocyte proliferation. To assess whether neutrophils directly influence the progression of autoreactivity in secondary lymphoid organs (SLOs), we characterized the localization and cell-cell contacts of splenic neutrophils at several stages in the progression of disease in the NZB/W murine model of lupus. Neutrophils accumulate in SLO over the course of lupus progression, preferentially localizing near T lymphocytes early in disease and B cells with advanced disease. RNA sequencing reveals that the splenic neutrophil transcriptional program changes significantly over the course of disease, with neutrophil expression of anti-inflammatory mediators peaking during early-stage and midstage disease, and evidence of neutrophil activation with advanced disease. To assess whether neutrophils exert predominantly protective or deleterious effects on loss of B cell self-tolerance in vivo, we depleted neutrophils at different stages of disease. Neutrophil depletion early in lupus resulted in a striking acceleration in the onset of renal disease, SLO germinal center formation, and autoreactive plasma cell production. In contrast, neutrophil depletion with more advanced disease did not alter systemic lupus erythematosus progression. These results demonstrate a surprising temporal and context-dependent role for neutrophils in restraining autoreactive B cell activation in lupus.

YO-10 - ROS is the boss

The production of reactive oxygen species (ROS) via the oxidative burst has been connected with promotion of inflammation and tissue damage, but in recent years has been implicated in regulation of inflammation. We investigated the effects of ROS on the murine model of lupus and in patients (SLE). The aim of this project was to elucidate the impact of the oxidative burst on the development of lupus-like autoimmunity. Lupus was induced by i.p. injection of pristane oil. Ex vivo phagocytosis assays were deployed to assess the uptake of cell debris in ROS deficient mice. The formation of neutrophil extracellular traps (NETs) was analysed by immune fluorescence microscopy. ROS activators were injected into mice to investigate the possible beneficial clinical effects on lupus pathology. The absence of ROS gives rise to dramatically exacerbated lupus. Aberrant phagocytosis in ROS-deficient animals leading to production of inflammatory mediators, accompanied by diminished pristane-induced but higher spontaneous formation of NETs could be responsible for this phenotype. Treatment with NOX2 agonists ameliorated the clinical course in mice, while application of a ROS scavenger worsened disease outcome. A fine-tuned balance of ROS-production is necessary to prevent autoimmunity and to avert the development of lupus in mice and men.

Effect of Secretome Mesenchymal Stem Cells On Expression Interleukin 10 And Interleukin 17 in Mice Lupus Model

Background: Systemic Lupus Erythematosus (SLE) is a chronic autoimmune inflammatory disease with extensive clinical features. The role of Interleukin 10 (IL-10) is to promote autoantibody production and autoreactive B cell proliferation. Interleukin 17 (IL-17) associated with pathogenesis of SLE and positively correlated with disease activity. Intraperitoneal pristane can induce lupus in mice. Mesenchymal stem cells secretome work in paracrine effects asantiinflammatory and immunomodulation agent by suppressing autoreactive T and B cell, which play an important role in pathogenesis of SLE. The aim of this study is to evaluate effect of mesenchymal stem cells secretome on the expression of IL-10 and IL-17 in murine lupus models induced by pristane.Methods: A randomized experimental study, post-test only control group design, samples using 21 female Mus Musculus mice strain Balb/C, divided into 3 groups: control group with intraperitoneal injection of 0.5 mL of 0.9% NaCl, treatment group with intraperitoneal injection of 0.5 mL pristane, therapy group with intraperitoneal injection of 0.5 mL pristane and 0.45 mL of secretome. Statistical analysis using ANOVA test. A p-value < 0.05 was considered statistically significant.Results: The results showed significant relationship between control and pristane groups both at the levels of IL-17 (control 6.9±1.95,pristane 9.9±2.27, pristane+secretome 6.1±1.95 p=0.016), and there are significant differences in the expression of IL-10 in the control group vs pristane group (-4,42±1,43 per 100 lymphocyte; p=0,006), pristane group vs pristane+secretome group (4,00±1,43 per 100 lymphocyte; p=0,012).Conclusion: Mesenchymal stem cells secretome decreased the expression of IL-10 and IL-17 levels in murine lupus models induced by pristane.Bangladesh Journal of Medical Science Vol.16(3) 2017 p.418-422

Oral idebenone attenuates murine lupus

Abstract A role for mitochondrial dysfunction has been proposed in the immune dysregulation and organ damage characteristic of systemic lupus erythematous (SLE) disease pathogenesis. We have now examined the role of drugs that may improve mitochondrial function in SLE symptomatology in murine models of lupus. Idebenone is a synthetic quinone analog compound of coenzyme Q10 that has been safely used in humans to treat diverse diseases where mitochondria function is deficient. Idebenone is considered a strong antioxidant able to protect cells against enhanced reactive oxygen species’ toxicity. Idebenone also improves electron transfer chain function in overloaded and/or damaged mitochondria. Idebenone was administered 250 mg/day/kg orally to two different mouse models of SLE starting in preclinical stages (10 weeks of age) for 6 weeks (MRL/lpr mice) or 4 months (NZM2328 mice). Disease attenuation was observed in both models at euthanasia. Specifically, proteinuria, intestinal inflammation and splenomegaly were decreased in both models upon exposure to idebenone, while levels of autoantibodies were not affected. In the MRL/lpr mouse model, skin lesions characteristic of this model were significantly decreased. In addition, levels of proinflammatory cytokines, type I IFNs and inflammasome-related genes were significantly decreased. No obvious toxicity was observed following exposure to idebenone. In conclusion, idebenone modulates lupus disease activity and organ damage severity and future studies should further address mechanism of action and potential role in human disease.

Role of Rab7 in activating NF-kB in B cells to mediate class-switching and plasma cell survival in antibody and autoantibody responses and to promote B cell lymphomagenesis

Abstract NF-kappaB activation mediates B cell class-switching to generate IgG, IgA and IgE as well as survival of plasma cells, as differentiated from B cells to secrete antibodies at a high rate. Here we have identified a B cell-intrinsic role of Rab7, a small GTPase located in endosomes, in activating NF-kappaB for class-switching and plasma cell survival. Mice that are deficient in Rab7 specifically in B cells or treated with CID 1067700, a Rab7-specific small molecule inhibitor, cannot mount T-independent or T-dependent switched antibody responses, despite normal B cell proliferation/survival and T cell/myeloid cells functions. Rab7 co-localizes, on endosomes, with the CD40 receptor that is internalized upon engagement and directly interacts with TRAF6, an adaptor of CD40 and TLR signaling for NF-kB activation, thereby forming complexes that transduce signals. Disruption of such complexes by CID 1067700 hampers NF-kappaB activation in normal B cells and abrogates NF-kappaB dysregulation in lupus B cells and B lymphoma cell lines, in which Rab7 is upregulated. Treatment with CID 1067700 reduces pathogenic IgG autoantibody responses in murine lupus models, leading to life-span extension, and prevents tumorigenesis in nude mice transplanted with B lymphoma cells. These, together with the rescue of class-switching/plasma cell survival in normal B cells and proliferation/survival of B lymphoma cells by enforced NF-kappaB activation, indicate that Rab7 plays an important role in NF-kappaB activation to mediate B cell differentiation and dysregulation and is a potential therapeutic target in lupus and B cell lymphomagenesis. Supported by NIH grants AI 079705, AI 105813/105813S1 (to P. C.) and AI 124172 (to Z. X.).