Complex Deposition In Kidney Research Articles

Autoantibodies in outbred Swiss Webster mice following exposure to gold and mercury

Exposure to heavy metals may have toxic effects on several human organs causing morbidity and mortality. Metals may trigger or exacerbate autoimmunity in humans. Inbred mouse strains with certain H-2 haplotypes are susceptible to xenobiotic-induced autoimmunity; and their immune response to metals such as mercury, gold, and silver have been explored. Serum antinuclear antibodies (ANA), polyclonal B-cell activation, hypergammaglobulinemia and tissue immune complex deposition are the main features of metal-induced autoimmunity in inbred mice. However, inbred mouse strains do not represent the genetic heterogeneity in humans. In this study, outbred Swiss Webster (SW) mice exposed to gold or mercury salts showed immune and autoimmune responses. Intramuscular injection of 22.5 mg/kg.bw aurothiomalate (AuTM) induced IgG ANA in SW mice starting after 5 weeks that persisted until week 15 although with a lower intensity. This was accompanied by elevated serum levels of total IgG antibodies against chromatin and total histones. Exposure to gold led to development of serum IgG autoantibodies corresponding to H1 and H2A histones, and dsDNA. Both gold and mercury induced polyclonal B-cell activation. Eight mg/L mercuric chloride (HgCl2) in drinking water, caused IgG antinucleolar antibodies (ANoA) after 5 weeks in SW mice accompanied by immune complex deposition in kidneys and spleen. Serum IgG antibodies corresponding to anti-fibrillarin, and anti-PM/Scl-100 antibodies, were observed in mercury-exposed SW mice. Gold and mercury trigger systemic autoimmune response in genetically heterogeneous outbred SW mice and suggest them as an appropriate model to study xenobiotic-induced autoimmunity.

Centrally Acting Angiotensin-Converting Enzyme Inhibitor Suppresses Type I Interferon Responses and Decreases Inflammation in the Periphery and the CNS in Lupus-Prone Mice.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by multi-organ damage. Neuropsychiatric lupus (NPSLE) is one of the most common manifestations of human SLE, often causing depression. Interferon-α (IFNα) is a central mediator in disease pathogenesis. Administration of IFNα to 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 (BK) into inactive peptides. We have previously shown in an in vitro model of mouse bone-marrow-derived dendritic cells (BMDC) and human peripheral blood mononuclear cells that captopril (a centrally acting ACE inhibitor-ACEi) suppressed Type I IFN responsive gene (IRG) expression. In this report, we used the MRL/lpr lupus-prone mouse model, an established model to study NPSLE, to determine the in vivo effects of captopril on Type I IFN and associated immune responses in the periphery and brain and effects on behavior. Administering captopril to MRL/lpr mice decreased expression of IRGs in brain, spleen and kidney, decreased circulating and tissue IFNα levels, decreased microglial activation (IBA-1 expression) and reduced depressive-like behavior. Serotonin levels that are decreased in depression were increased by captopril treatment. Captopril also reduced autoantibody levels in plasma and immune complex deposition in kidney and brain. Thus, ACEi’s may have potential for therapeutic use for systemic and NPSLE.

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.

Inhibition of G Protein βγ Subunit Signaling Abrogates Nephritis in Lupus-Prone Mice.

Despite considerable advances in the understanding of systemic lupus erythematosus (SLE), there is still an urgent need for new and more targeted treatment approaches. We previously demonstrated that small-molecule blockade of G protein βγ subunit (Gβγ) signaling inhibits acute inflammation through inhibition of chemokine receptor signal transduction. We undertook this study to determine whether inhibition of Gβγ signaling ameliorates disease in a mouse model of SLE. Lupus-prone (NZB × NZW)F1 female mice were prophylactically or therapeutically treated with the small-molecule Gβγ inhibitor gallein. Tissue samples were analyzed by flow cytometry and immunohistochemistry. The development and extent of nephritis were assessed by monitoring proteinuria and by immunohistochemical analysis. Serum immunoglobulin levels were measured by enzyme-linked immunosorbent assay, and total IgG and anti-double-stranded DNA (anti-dsDNA) antibody-secreting cells were measured by enzyme-linked immunospot assay. Gallein inhibited accumulation of T cells and germinal center (GC) B cells in the spleen. Both prophylactic and therapeutic treatment reduced GC size, decreased antibody-secreting cell production in the spleen, and markedly decreased accumulation of autoreactive anti-dsDNA antibody-secreting cells in kidneys. Gallein also reduced immune complex deposition in kidneys. Finally, gallein treatment dramatically inhibited kidney inflammation, prevented glomerular damage, and decreased proteinuria. Mechanistically, gallein inhibited immune cell migration and signaling in response to chemokines in vitro, which suggests that its mechanisms of action in vivo are inhibition of migration of immune cells to sites of inflammation and inhibition of immune cell maturation. Overall, these data demonstrate the potential use of gallein or novel inhibitors of Gβγ signaling in SLE treatment.

Distinct effects of mycophenolate mofetil and cyclophosphamide on renal fibrosis in NZBWF1/J mice

Progression to chronic renal failure varies between patients with lupus nephritis. We compared the effects of mycophenolate mofetil (MMF) and cyclophosphamide (CTX), on renal histology and cellular pathways of fibrosis in murine lupus nephritis. Female NZBWF1/J mice were randomized to treatment with vehicle, methylprednisolone (MP) alone, MMF + MP or CTX + MP for up to 12 weeks, and the effects on clinical parameters, renal histology, and fibrotic processes were investigated. Treatment with MMF + MP or CTX + MP both improved survival, renal function, and decreased anti-dsDNA antibody level and immune complex deposition in kidneys of mice with active nephritis. Vehicle-treated mice showed progressive increase in mesangial proliferation, inflammatory cell infiltration and renal tubular atrophy, associated with PKC-α activation, increased TGF-β1 expression and increased matrix protein deposition. MP treatment alone did not have any significant effect. MMF + MP or CTX + MP treatment for 12 weeks reduced these abnormalities. MMF + MP was more effective than CTX + MP in suppressing fibrotic mediators, histological fibrosis score and expression of TGF-β1, fibronectin and collagen I in the kidney. Results from in vitro experiments on human mesangial cells (HMC) showed that mycophenolic acid (MPA) was more effective than CTX in suppressing PKC-α activation and TGF-β1 secretion induced by human polyclonal anti-dsDNA antibodies. While both MPA and CTX decreased TGF-β1- and TNF-α-induced fibronectin synthesis, only MPA decreased IL-6 induced fibronectin synthesis. MPA and CTX show distinct effects on fibrotic and inflammatory processes in NZBWF1/J murine lupus nephritis, suggesting that MMF + MP may be more effective than CTX + MP in preserving normal renal histology in lupus nephritis.

Differential regulation of immune responses in MyD88-deficient mice by cytokine-expressing Salmonella typhimurium (P4046)

Abstract MyD88 is a critical component of most TLR signaling pathways. Earlier we demonstrated that MyD88-deficient (MyD88-/-) mice are hypersusceptible to infection by a vaccine strain (aroA-/aroD-) of Salmonella typhimurium (designated BRD509). Curiously, infected mice exhibited a state of hypergammaglobulinemia, with high levels of anti-Salmonella Abs of all IgG isotypes. The dysregulated Ab response also lead to production of anti-dsDNA and anti-thyroglobulin autoantibodies and immune complex deposition in kidneys. Increased susceptibility of MyD88-/- mice has been linked to poor type-1 cytokine responses. Therefore, we assessed the response of these mice to infection with a S. typhimurium engineered to express murine IFN-γ (GIDIFN). Infection studies using different doses of BRD509 and GIDIFN strains revealed that the latter strain was >100-fold less virulent in MyD88-/- mice than BRD509 and correlated with decreased bacterial loads in systemic organs and robust pathogen clearance starting at 7 days of infection. Although GIDIFN-infected mice exhibited high Ab titers, the degree of autoreactivity was significantly decreased compared to BRD509-infected animals. Our data suggest that TLR-MyD88 signaling pathway is critical for controlling Ab responses to bacterial antigens and for maintaining B cell self-tolerance and demonstrate that the two processes may be unlinked through the use of cytokine-expressing bacterial strains that modulate host immune responses.

The role of deltex1 in regulating T cell tolerance (63.20)

Abstract Deltex1 (DTX1) is an E3 ubiquitin ligase and is suggested to be a mediator of Notch signaling. Our previous study found that DTX1 supressses T cell activation and promotes MEKK1 degradation. In this study, we found that T cell activation was partially suppressed by DTX1 with either inactive mutation of RING finger domain or deletion of WWE domain. In addition, we identified another suppressive mechanism of DTX1 by upregulation of Gadd45β, an inhibitor of JNK activation. DTX1 may promote the expression of Gadd45β in the absence of RF domain or WWE domain. Therefore, DTX1 inhibit T cell activation by either E3-dependent or E3-independent mechanisms. To further investigate the physiological function of DTX1 in lymphocyte development and activation, Dtx1-deficient mice were generated. T cell development in thymus and spleen was normal. B cell development in bone marrow was not affected but margine zone B cell population in spleen was reduced in Dtx1-deficient mice. T cell proliferation, cytokine production and MAPK activation were enhanced in Dtx1-deficient T cells. In addition, enhanced autoantibody production, elevated immune complex deposition in kidney and increased leukocyte infiltration in lung and liver were observed in aged Dtx1-deficient mice. These results suggest that DTX1 plays a role in T cell tolerance induction.

Developmental exposure to 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin alters postnatal T cell phenotypes and T cell function and exacerbates autoimmune lupus in 24‐week‐old SNF1 mice

Untreated, more than 95% of female SWR x NZB: F(1) (SNF(1)) mice spontaneously develop a fatal lupus-like glomerulonephritis by 8 months-of-age, while disease onset in males is much slower. : Timed-pregnant SNF(1) mice (10 per treatment) were exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on gestational day (GD) 12 by oral maternal gavage with 0, 40, or 80 microg/kg TCDD. Offspring of the TCDD-exposed dams showed numerous alterations in T lineage cells at 24 weeks-of-age. Females but not males showed decreased CD4(+)8(+) and increased CD4(-)8(-) thymocytes. Females also showed increased autoreactive CD4(+)Vbeta17(a+) axillary and inguinal lymph node T cells. Concanavalin A-stimulated splenocytes from prenatal TCDD-treated mice produced decreased interleukin 17 (IL-17) in the females while males showed increased IL-2 and IFN-gamma, and diminished IL-4. Mitogen-stimulated pan-lymphoproliferative responses were significantly increased across sex by TCDD. Anti-IgG and anti-C3 immune complex deposition in kidneys was present in the males after TCDD, and visibly worsened in females. Developmental TCDD exposure can permanently alter T lymphopoiesis in autoimmune-prone SNF1 mice. The alteration profile is beyond the classic immune suppression response, to also include exacerbation and induction of a lupuslike autoimmune disease.

The proapoptotic and antimitogenic protein p66SHC acts as a negative regulator of lymphocyte activation and autoimmunity

AbstractThe ShcA locus encodes 3 protein isoforms that differ in tissue specificity, subcellular localization, and function. Among these, p66Shc inhibits TCR coupling to the Ras/MAPK pathway and primes T cells to undergo apoptotic death. We have investigated the outcome of p66Shc deficiency on lymphocyte development and homeostasis. We show that p66Shc−/− mice develop an age-related lupus-like autoimmune disease characterized by spontaneous peripheral T- and B-cell activation and proliferation, autoantibody production, and immune complex deposition in kidney and skin, resulting in autoimmune glomerulonephritis and alopecia. p66Shc−/− lymphocytes display enhanced proliferation in response to antigen receptor engagement in vitro and more robust immune responses both to vaccination and to allergen sensitization in vivo. The data identify p66Shc as a negative regulator of lymphocyte activation and show that loss of this protein results in breaking of immunologic tolerance and development of systemic autoimmunity.

Clinical and pathological characteristics and outcomes of Chinese patients with primary anti‐neutrophil cytoplasmic antibodies‐associated systemic vasculitis with immune complex deposition in kidney

To analyse the clinical and pathological characteristics of Chinese patients with immune complex deposition in kidney in anti-neutrophil cytoplasmic antibodies (ANCA)-positive vasculitis. Enrolled in this study are patients with immune complex deposition in kidney in ANCA-positive vasculitis diagnosed in Peking University First Hospital. Their clinical and pathological data were collected and analysed. Twenty-three patients were eligible. Fifteen patients were with microscopic polyangiitis and eight patients were with Wegener's granulomatosis. The mean age was 48.8 years and with a male/female ratio of 10/13. The interval, between onset of disease and the diagnosis of disease, was 429.6 +/- 693.3 days. All patients had clinical evidence of renal involvement. The major immunoglobulin deposited was IgM and the main locations were mesangial and sub-epithelial area. Four patients also presented features of membranous nephropathy and six patients presented features of IgA nephropathy. About 52.2% of patients had hypocomplementaemia. All patients received immunosuppressive therapy and all of them achieved clinical remission. Patients were followed for about 28.8 +/- 25.3 months. Nine patients kept clinical remission, nine patients progressed to end-stage renal disease and five patients died. When these patients are compared with patients who had classical pauci-immune vasculitis, they had greater proteinuria (P < 0.05), higher prevalence of hypocomplementaemia (P < 0.05) and greater glomerular cellularity (P < 0.05). The present study showed that the features of patients with ANCA-associated vasculitis with immune complex deposition in kidney were similar with classical 'pauci-immune' vasculitis except for more proteinuria, more hypocomplementaemia and greater glomerular hypercellularity.

Necrotic Cells Induce Systemic Autoimmune Disease in vivo by Activation of Dendritic Cells (DCs)

RATIONALE: The mechanism for autoantibody production in systemic lupus erythematosus remains unclear. Dying cells are likely to be a source of autoantigens. We hypothesized that DCs may take up dying cells and induce autoimmunity.METHODS: Bone-marrow-derived DCs were co-cultured with syngeneic necrotic (freezing-thawing) or apoptotic (UV-irradiated) splenocytes. After 24 co-culture, DCs capturing dying cells were injected into female 11-week-old MRL/MP-+/+ mice. Blood was taken at two-week interval and was determined by ELISA for autoantibody level. Morphological changes in kidney were examined by immunofluorescent staining and transmission electron microscopy. T-cell stimulatory capacity of DCs was determined by mixed leukocyte reaction.RESULTS: Compared with DCs with apoptotic cells, DCs phagocytosing necrotic cells induced significantly higher serum levels of anti-double-stranded DNA antibodies IgG and IgG2a, (n = 3∼5, P<0.01), and higher level of proteinuria (P<0.05). Immunofluorescent staining showed strong immune complex deposition in kidney, which was further confirmed by transmission electron microscopy. Mice receiving DCs with necrotic cells developed subsequently a ‘butterfly’ facial skin lesion similar to that observed in human lupus. Flow cytometry analysis demonstrated that necrotic cells upregulated expression of surface MHC class II, CD80, CD86 and CD40 of DCs comparably to apoptotic cells. In response to lipopolysaccharide, DCs that have captured necrotic cells significantly secreted substantial TH1 cytokine INF-g at 24, 48, 72 hours (P<0.01). DCs that have phagocytosed necrotic cells significantly increased the proliferation of C57BL/6N and MRL/+ T cells (P<0.05).CONCLUSIONS: Activation of DCs by necrotic cells might promote TH1 autoimmune responses, leading to the systemic autoimmune disease in vivo. RATIONALE: The mechanism for autoantibody production in systemic lupus erythematosus remains unclear. Dying cells are likely to be a source of autoantigens. We hypothesized that DCs may take up dying cells and induce autoimmunity. METHODS: Bone-marrow-derived DCs were co-cultured with syngeneic necrotic (freezing-thawing) or apoptotic (UV-irradiated) splenocytes. After 24 co-culture, DCs capturing dying cells were injected into female 11-week-old MRL/MP-+/+ mice. Blood was taken at two-week interval and was determined by ELISA for autoantibody level. Morphological changes in kidney were examined by immunofluorescent staining and transmission electron microscopy. T-cell stimulatory capacity of DCs was determined by mixed leukocyte reaction. RESULTS: Compared with DCs with apoptotic cells, DCs phagocytosing necrotic cells induced significantly higher serum levels of anti-double-stranded DNA antibodies IgG and IgG2a, (n = 3∼5, P<0.01), and higher level of proteinuria (P<0.05). Immunofluorescent staining showed strong immune complex deposition in kidney, which was further confirmed by transmission electron microscopy. Mice receiving DCs with necrotic cells developed subsequently a ‘butterfly’ facial skin lesion similar to that observed in human lupus. Flow cytometry analysis demonstrated that necrotic cells upregulated expression of surface MHC class II, CD80, CD86 and CD40 of DCs comparably to apoptotic cells. In response to lipopolysaccharide, DCs that have captured necrotic cells significantly secreted substantial TH1 cytokine INF-g at 24, 48, 72 hours (P<0.01). DCs that have phagocytosed necrotic cells significantly increased the proliferation of C57BL/6N and MRL/+ T cells (P<0.05). CONCLUSIONS: Activation of DCs by necrotic cells might promote TH1 autoimmune responses, leading to the systemic autoimmune disease in vivo.

The diverse pathogenic potential of anti-DNA antibodies from various sources to induce experimental systemic lupus erythematosus.

It has previously been shown that immunization with pathogenic anti-DNA idiotypes (Ids; e.g. 16/6 Id) leads to the induction of experimental system lupus erythematosus (SLF) in naive mice. The disease is characterized by serological (e.g. anti-double-strand DNA), clinical (elevation of erythrocyte sedimentation rate, leukopenia and proteinuria) and histological (immune complex deposition in kidneys) parameters. To determine whether the 16/6 Id carrying anti-DNA antibodies has unique pathogenic ability, in the current study we have employed diverse sources of anti-DNA antibodies to induce experimental SLE. An IgM anti-DNA antibody lacking the 16/6 Id was able to induce the production of the serological markers of experimental SLE, but not the clinico-histological findings. Furthermore, an IgA anti-DNA (16/6 Id derived from the serum of a patient with celiac disease was very effective in inducing the whole presentation of experimental SLE. Other anti-DNA antibodies failed to induce the autoimmune condition. Combined with our previous experience, the current study points to the diverse potential of various anti-DNA antibodies to induce SLE. The 16/6 Id is only one of a list of the potent pathogenic anti-DNA Ids. These facts may explain in part the diversity of clinical presentations of SLE, including asymptomatic subjects who carry high serum titers of anti-DNA antibodies.

Relationship between circulating immune complexes and urinary antigens in human malignancy.

Urine samples obtained from patients with histologically proved melanoma and sarcoma were analyzed for the presence of tumor-associated antigens by complement fixation and enzyme immunoassay. Also, serum samples obtained during 24-hour urine collection from these patients were analyzed for circulating immune complexes by the complement consumption method and by the K562 radiometric assay. Of 36 cancer patients who were positive for urinary antigen (UA) by both assays, 28 (78%) were also positive for CIC in the two assays, six (17%) were positive in one of the two CIC-detection assays, and two (5%) were negative in both assays. Of 24 patients that were negative for CIC in both assays, ten (42%) were also negative for UA in both assays, i.e., complement fixation and enzyme immunoassay; 12 (50%) were negative by one of the two assays; and only two (8%) exhibited UA by both assays. This relationship was more striking for melanoma than sarcoma patients. In a melanoma patient whose samples were studied sequentially during his thermochemotherapy, the fluctuations in CIC and UA were parallel. These results suggest that excretion of tumor-associated antigen into urine is not an isolated phenomenon; rather, immune complex deposition in kidneys appears to cause glomerular damage which may allow the passage of the antigens into the urine.