Peroxidasin Is a Novel Target of Autoantibodies in Lupus Nephritis.
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ABSTRACT:
SUBMITTER: Manral P
PROVIDER: S-EPMC6611989 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Patients with systemic lupus erythematosus (SLE) frequently develop lupus nephritis (LN), a complication frequently leading to end stage kidney disease. Immune complex deposition in the glomerulus is central to the development of LN. Using a targeted proteomic approach, we tested the hypothesis that autoantibodies targeting glomerular antigens contribute to the development of LN.Human podocyte and glomerular proteins were separated by SDS-PAGE and immunoblotted with sera from SLE patients with and without LN. The regions of those gels corresponding to reactive bands observed with sera from LN patients were analyzed using LC-MS/MS.LN reactive bands were seen at approximately 50 kDa in podocyte extracts and between 36 and 50 kDa in glomerular extracts. Those bands were analyzed by LC-MS/MS and 102 overlapping proteins were identified. Bioinformatic analysis determined that 36 of those proteins were membrane associated, including a protein previously suggested to contribute to glomerulonephritis and LN, annexin A2. By ELISA, patients with proliferative LN demonstrated significantly increased antibodies against annexin A2.Proteomic approaches identified multiple candidate antigens for autoantibodies in patients with LN. Serum antibodies against annexin A2 were significantly elevated in subjects with proliferative LN, validating those antibodies as potential biomarkers.
| S-EPMC4690797 | biostudies-literature
Project description:PurposeAnti-complement factor H (CFH) autoantibodies could be detected in lupus and its significance remained to be elucidated. Herein, we aimed to explore the roles of anti-CFH autoantibodies based on pristane-induced lupus mice.MethodsTwenty-four female Balb/c mice were randomly divided into four groups, with one group injected with pristane (pristane group), one group with pristane and then human CFH (hCFH) (pristane-CFH group) 3 times, and the other two as vertical controls, PBS group and PBS-CFH group. Histopathological analysis was performed six months after pristane administration. Levels of hCFH, anti-CFH autoantibodies and anti-dsDNA antibody were detected. Murine IgG (mIgG) were purified and cross-reactivity, epitopes, subclasses and functional analysis were further evaluated in vitro.ResultsImmunization with hCFH and subsequent development of anti-CFH autoantibodies significantly attenuated nephritis of pristane-induced lupus, including lower levels of urinary protein and serum creatinine, decreased levels of serum anti-dsDNA antibody, greatly ameliorated renal histopathologic damage, decreased IgG, complements (C1q, C3) deposits and lower inflammatory factor (IL-6) expression in glomerulus. Furthermore, the purified mIgG (contained anti-CFH autoantibodies) could recognize both hCFH and murine CFH, and the epitopes were predominantly located in hCFH short consensus repeats (SCRs) 1-4, 7 and 11-14. The IgG subclasses were predominant IgG1. The autoantibodies could enhance the binding between hCFH and C3b, and increase factor I mediated-C3b lysis in vitro.ConclusionOur results suggested that anti-CFH autoantibodies could attenuate pristane-induced lupus nephritis by increasing bio-functions of CFH on regulating complement activation and controlling inflammation.
| S-EPMC10667379 | biostudies-literature
Project description:Systemic lupus erythematosus (SLE) is characterized by production of a variety of autoantibodies. Although anti-double-stranded DNA (anti-dsDNA) antibodies contribute to the pathogenesis of lupus nephritis (LN), they are not sufficient for diagnosis and evaluation of disease activity. To obtain other autoantibodies associated with LN, we screened autoantigens reacting with the sera of LN patients by using an N-terminal biotinylated protein library created from a wheat cell-free protein production system. We screened 17 proteins that showed higher positive signals in the active phase than in the inactive phase of SLE, and higher positive signals in the serum of SLE patient with nephritis than in that of patient without nephritis. Of these, two LN-associated autoantigens, ribosomal RNA-processing protein 8 (RRP8) and spermatid nuclear transition protein 1 (TNP1) were identified by immunoprecipitation and immunofluorescence of renal tissues. Circulating anti-RRP8 and anti-TNP1 autoantibodies were recognized and deposited as an immune complex (IC) in glomeruli. IC was deposited preferentially in glomeruli rather than in other organs in C57BL/6 mice injected with RRP8 or TNP1. ELISA analysis of sera from patients with various rheumatic diseases demonstrated reactivity for RRP8 and TNP1 in 20% and 14.7% of SLE patients, respectively, whereas there was little or no reactivity in patients with other rheumatic diseases. Among SLE patients, 63.6% and 45.5% of those with LN were positive for anti-RRP8 and anti-TNP1 antibodies, compared with 12.5% and 9.4% of SLE patients without nephritis, respectively. Both proteins are cationic, and their respective antibodies did not cross-react with dsDNA. These proteins released from apoptotic cells form ICs with each autoantibody, and their ICs may become trapped at anionic sites in the glomerular basement membrane, leading to deposition in glomeruli. These autoantibodies may be useful for prediction of LN in subsets of SLE patients who are negative for anti-dsDNA antibodies.
| S-EPMC4476694 | biostudies-literature
Project description:The mitochondrion supplies energy to the cell and regulates apoptosis. Unlike other mammalian organelles, mitochondria are formed by binary fission and cannot be directly produced by the cell. They contain numerous copies of a compact circular genome that encodes RNA molecules and proteins involved in mitochondrial oxidative phosphorylation. Whereas, mitochondrial DNA (mtDNA) activates the innate immune system if present in the cytosol or the extracellular milieu, it is also the target of circulating autoantibodies in systemic lupus erythematosus (SLE). However, it is not known whether mitochondrial RNA is also recognized by autoantibodies in SLE. In the present study, we evaluated the presence of autoantibodies targeting mitochondrial RNA (AmtRNA) in SLE. We quantified AmtRNA in an inducible model of murine SLE. The AmtRNA were also determined in SLE patients and healthy volunteers. AmtRNA titers were measured in both our induced model of murine SLE and in human SLE, and biostatistical analyses were performed to determine whether the presence and/or levels of AmtRNA were associated with clinical features expressed by SLE patients. Both IgG and IgM classes of AmtRNA were increased in SLE patients (n = 86) compared to healthy controls (n = 30) (p < 0.0001 and p = 0.0493, respectively). AmtRNA IgG levels correlated with anti-mtDNA-IgG titers (r s = 0.54, p < 0.0001) as well as with both IgG and IgM against β-2-glycoprotein I (anti-β2GPI; r s = 0.22, p = 0.05), and AmtRNA-IgG antibodies were present at higher levels when patients were positive for autoantibodies to double-stranded-genomic DNA (p < 0.0001). AmtRNA-IgG were able to specifically discriminate SLE patients from healthy controls, and were negatively associated with plaque formation (p = 0.04) and lupus nephritis (p = 0.03). Conversely, AmtRNA-IgM titers correlated with those of anti-β2GPI-IgM (r s = 0.48, p < 0.0001). AmtRNA-IgM were higher when patients were positive for anticardiolipin antibodies (aCL-IgG: p = 0.01; aCL-IgM: p = 0.002), but AmtRNA-IgM were not associated with any of the clinical manifestations assessed. These findings identify mtRNA as a novel mitochondrial antigen target in SLE, and support the concept that mitochondria may provide an important source of circulating autoantigens in SLE.
| S-EPMC6524553 | biostudies-literature
Project description:BackgroundIn this study, we have investigated the potential regulatory mechanisms of IL-35 to relieve lupus nephritis (LN) through regulating Janus kinase (JAK)/signal transducers and activators of transcription (STAT) signaling pathway in mesangial cells.ResultsAmong 105 significant differentially expressed proteins (DEPs) between juvenile systemic lupus erythematosus (JSLE) patients with LN and healthy controls, LAIR1, PDGFRβ, VTN, EPHB4, and EPHA4 were downregulated in JSLE-LN. They consist of an interactive network with PTPN11 and FN1, which involved in IL-35-related JAK/STAT signaling pathway. Besides, urinary LAIR1 was significantly correlated with JSLE-LN clinical parameters such as SLEDAI-2K, %CD19+ B, and %CD3+ T cells. Through bioinformatics analysis of co-immunoprecipitation with mass spectrometry results, including GO, KEGG, and STRING, five genes interacted with Lair1 were upregulated by IL-35, but only Myh10 was downregulated. Therefore, we presumed an interactive network among these DEPs, JAK/STAT, and IL-35. Moreover, the downregulated phosphorylated (p)-STAT3, p-p38 MAPK, and p-ERK, and the upregulated p-JAK2/p-STAT1/4 in IL-35 overexpressed mesangial cells, and RNA-sequencing results validated the potential regulatory mechanisms of IL-35 in alleviating JSLE-LN disease. Moreover, the relieved histopathological features of nephritis including urine protein and leukocyte scores, a decreased %CD90+ αSMA+ mesangial cells and pro-inflammatory cytokines, the inactivated JAK/STAT signals and the significant upregulated Tregs in spleen, thymus and peripheral blood were validated in Tregs and IL-35 overexpression plasmid-treated lupus mice.ConclusionsOur study provided a reference proteomic map of urinary biomarkers for JSLE-LN and elucidated evidence that IL-35 may regulate the interactive network of LAIR1-PTPN11-JAK-STAT-FN1 to affect JAK/STAT and MAPK signaling pathways to alleviate inflammation in JSLE-LN. This finding may provide a further prospective mechanism for JSLE-LN clinical treatment.
| S-EPMC7851357 | biostudies-literature
Project description:Autoantibodies against the major acute-phase reactant C-reactive protein (CRP) are frequently found in patients with lupus nephritis. Further defining the autoimmune epitopes on CRP may not only improve patient stratification but also, hint at mechanisms of CRP action. Herein, we show that amino acids 35-47 constitute the major epitope recognized by anti-CRP autoantibodies in patients with lupus nephritis. Notably, the presence of autoantibodies against amino acids 35-47 associated with more severe renal damage and predicted worse outcome. This epitope is exposed on CRP only after irreversible structure changes, yielding a conformationally altered form termed modified or monomeric CRP (mCRP). ELISA and surface plasmon resonance assays showed that amino acids 35-47 mediate the interaction of mCRP with complement factor H, an inhibitor of alternative pathway activation, and this interaction greatly enhanced the in vitro cofactor activity of complement factor H. In contrast, autoantibodies against amino acids 35-47 inhibited these actions of mCRP. Our results thus provide evidence for the in vivo generation of mCRP in a human disease and suggest that mCRP actively controls the pathogenesis of lupus nephritis by regulating complement activation. Therefore, amino acids 35-47 constitute a functional autoimmune epitope on CRP that can be targeted therapeutically and diagnostically.
| S-EPMC5619952 | biostudies-literature
Project description:IgG antibodies cause inflammation and organ damage in autoimmune diseases such as systemic lupus erythematosus (SLE). We investigated the metabolic profile of macrophages isolated from inflamed tissues in immune complex (IC)-associated diseases, including SLE and rheumatoid arthritis, and following IgG Fcγ receptor cross-linking. We found that human and mouse macrophages undergo a switch to glycolysis in response to IgG IC stimulation, mirroring macrophage metabolic changes in inflamed tissue in vivo. This metabolic reprogramming was required to generate a number of proinflammatory mediators, including IL-1β, and was dependent on mTOR and hypoxia-inducible factor (HIF)1α. Inhibition of glycolysis, or genetic depletion of HIF1α, attenuated IgG IC-induced activation of macrophages in vitro, including primary human kidney macrophages. In vivo, glycolysis inhibition led to a reduction in kidney macrophage IL-1β and reduced neutrophil recruitment in a murine model of antibody-mediated nephritis. Together, our data reveal the molecular mechanisms underpinning FcγR-mediated metabolic reprogramming in macrophages and suggest a therapeutic strategy for autoantibody-induced inflammation, including lupus nephritis.
| S-EPMC7334513 | biostudies-literature
Project description:Immune complex accumulation in the kidney is the hallmark of lupus nephritis and triggers a series of events that result in kidney inflammation and injury. Cytotoxic agents and corticosteroids are standard of care for lupus nephritis treatment, but are associated with considerable morbidity and suboptimal outcomes. Recently, there has been interest in using novel biologic agents and small molecules to treat lupus nephritis. These therapies can be broadly categorized as anti-inflammatory (laquinamod, anti-tumor necrosis factor-like weak inducer of apotosis, anti-C5, and retinoids), antiautoimmunity (anti-CD20, anti-interferon α, and costimulatory blockers), or both (anti-interleukin 6 and proteasome inhibitors). Recent lupus nephritis clinical trials applied biologics or small molecules of any category to induction treatment, seeking short-term end points of complete renal response. These trials in general have not succeeded. When lupus nephritis comes to clinical attention during the inflammatory stage of the disease, the autoimmune stage leading to kidney inflammation will have been active for some time. The optimal approach for using novel therapies may be to initially target kidney inflammation to preserve renal parenchyma, followed by suppression of autoimmunity. In this review, we discuss novel lupus nephritis therapies and how they fit into a combinatorial treatment strategy based on the pathogenic stage.
| S-EPMC4159074 | biostudies-literature
Project description:Membranous lupus nephritis is a frequent cause of nephrotic syndrome in patients with systemic lupus erythematosus. Unlike phospholipase A2 receptor or thrombospondin type 1 domain containing 7A-associated membranous nephropathy, where known antibodies can be detected within sera by indirect immunofluorescence and/or enzyme-linked immunosorbent assay, it is not possible to monitor disease activity in membranous lupus nephritis where the target autoantigens are mostly unknown. Determination of the target autoantigen has diagnostic significance, informs prognosis, and allows for non-invasive monitoring of disease activity in serum. We utilized mass spectrometry for antigen discovery of laser capture microdissected glomeruli from formalin-fixed paraffin embedded tissue and tissue IgG immunoprecipitation studies from frozen kidney biopsy tissue. We identified neural cell adhesion molecule 1 (NCAM1) to be a target antigen in membranous lupus nephritis and within rare cases of primary membranous nephropathy. The prevalence of NCAM1-associated membranous neuropathy was 5.7% of cases of membranous lupus nephritis. NCAM1 co-localizes with IgG within glomerular immune deposits. Additionally, serum from NCAM1 patients showed reactivity to NCAM1 recombinant protein. The presence of anti-NCAM1 antibodies in sera could allow for non-invasive monitoring of the disease. We propose that NCAM1 is a target autoantigen in a subset of patients with membranous lupus nephritis. Future studies are needed to determine whether anti-NCAM1 antibody levels correlate with disease activity or response to therapy.
2020-10-19 | PXD021123 | Pride
Project description:Persistent exposure of the immune system to death cell debris leads to autoantibodies against chromatin in patients with systemic lupus erythematosus (SLE). Deposition of anti-chromatin/chromatin complexes can instigate inflammation in multiple organs including the kidney. Previously we identified specific cell death-associated histone modifications as targets of autoantibodies in SLE. In this study we addressed, in a large cohort of SLE patients and controls, the question whether plasma reactivities with specific histone peptides associated with serology and clinical features. Plasma from SLE patients with and without lupus nephritis, disease controls, and healthy controls, were tested in ELISA with histone H4 peptide acetylated at lysines 8, 12 and 16 (H4pac), H2B peptide acetylated at lysine 12 (H2Bpac), H3 peptide trimethylated at lysine 27 (H3pme), and their unmodified equivalents. SLE patients displayed a higher reactivity with the modified equivalent of each peptide. Reactivity with H4pac showed both a high sensitivity (89%) and specificity (91%) for SLE, while H2Bpac exhibited a high specificity (96%) but lower sensitivity (69%). Reactivity with H3pme appeared not specific for SLE. Anti-H4pac and anti-H2Bpac reactivity demonstrated a high correlation with disease activity. Moreover, patients reacting with multiple modified histone peptides exhibited higher SLEDAI and lower C3 levels. SLE patients with renal involvement showed higher reactivity with H2B/H2Bpac and a more pronounced reactivity with the modified equivalent of H3pme and H2Bpac. In conclusion, reactivity with H4pac and H2Bpac is specific for SLE patients and correlates with disease activity, whereas reactivity with H2Bpac is in particular associated with lupus nephritis.
| S-EPMC5079581 | biostudies-literature