FcγRIIA expression accelerates nephritis and increases platelet activation in systemic lupus erythematosus.
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ABSTRACT:
SUBMITTER: Melki I
PROVIDER: S-EPMC7751357 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Systemic lupus erythematosus (SLE) is a polyclonal autoimmune syndrome directed against multiple nuclear autoantigens. Although RNA and DNA seem to have identical immunostimulatory effects on systemic and intrarenal inflammation, each seems to differ with regard to the propensity to induce mitogenic effects such as lymphoproliferation. To identify potential mechanisms by which DNA specifically contributes to the pathogenesis of lupus nephritis, we stimulated cells with immunostimulatory DNA or RNA in vitro and used microarray to compare the transcriptomes of RNA- and DNA-induced genes. Immunostimulatory DNA, but not RNA, induced Mdm2, which is a negative regulator of p53. In vivo, we observed greater expression and activation of Mdm2 in the spleen and kidneys in a mouse model of lupus (MRL-Fas(lpr) mice) than healthy controls. Treatment of MRL-Fas(lpr) mice with the Mdm2 inhibitor nutlin-3a prevented nephritis and lung disease and significantly prolonged survival. Inhibition of Mdm2 reduced systemic inflammation and abrogated immune complex disease by suppressing plasma cells and the production of lupus autoantibodies. In addition, nutlin-3a suppressed the abnormal expansion of all T cell subsets, including CD3(+)CD4(-)CD8(-) T cells, which associated with attenuated systemic inflammation. However, inhibiting Mdm2 did not cause myelosuppression or affect splenic regulatory T cells, neutrophils, dendritic cells, or monocytes. Taken together, these data suggest that the induction of Mdm2 promotes the expansion of plasma cells and CD3(+)CD4(-)CD8(-) T cells, which cause autoantibody production and immune complex disease in MRL-Fas(lpr) mice. Antagonizing Mdm2 may have therapeutic potential in lupus nephritis.
| S-EPMC3279995 | biostudies-literature
Project description:Systemic lupus erythematosus (SLE) is a chronic inflammatory disease characterized by a loss of tolerance to self-antigens and the production of high titers of serum autoantibodies. Lupus nephritis can affect up to 74% of SLE patients, particularly those of Hispanic and African ancestries, and remains a major cause of morbidity and mortality. A genetic etiology in SLE is now well substantiated. Thanks to extensive collaborations, extraordinary progress has been made in the past few years and the number of confirmed genes predisposing to SLE has catapulted to approximately 30. Studies of other forms of genetic variation, such as copy number variants and epigenetic alterations, are emerging and promise to revolutionize our knowledge about disease mechanisms. However, to date little progress has been made on the identification of genetic factors specific to lupus nephritis. On the near horizon, two large-scale efforts, a collaborative meta-analysis of lupus nephritis based on all genome-wide association data in Caucasians and parallel scans in four other ethnicities, are poised to make fundamental discoveries in the genetics of lupus nephritis. Collectively, these findings will show that a broad array of pathways underlines the genetic heterogeneity of SLE and lupus nephritis, and provide potential avenues for the development of novel therapies.
| S-EPMC2847514 | biostudies-literature
Project description:Lupus nephritis is a manifestation of SLE resulting from glomerular immune complex deposition and inflammation. Lupus nephritis demonstrates familial aggregation and accounts for significant morbidity and mortality. We completed a meta-analysis of three genome-wide association studies of SLE to identify lupus nephritis-predisposing loci. Through genotyping and imputation, >1.6 million markers were assessed in 2000 unrelated women of European descent with SLE (588 patients with lupus nephritis and 1412 patients with lupus without nephritis). Tests of association were computed using logistic regression adjusting for population substructure. The strongest evidence for association was observed outside the MHC and included markers localized to 4q11-q13 (PDGFRA, GSX2; P=4.5×10(-7)), 16p12 (SLC5A11; P=5.1×10(-7)), 6p22 (ID4; P=7.4×10(-7)), and 8q24.12 (HAS2, SNTB1; P=1.1×10(-6)). Both HLA-DR2 and HLA-DR3, two well established lupus susceptibility loci, showed evidence of association with lupus nephritis (P=0.06 and P=3.7×10(-5), respectively). Within the class I region, rs9263871 (C6orf15-HCG22) had the strongest evidence of association with lupus nephritis independent of HLA-DR2 and HLA-DR3 (P=8.5×10(-6)). Consistent with a functional role in lupus nephritis, intra-renal mRNA levels of PDGFRA and associated pathway members showed significant enrichment in patients with lupus nephritis (n=32) compared with controls (n=15). Results from this large-scale genome-wide investigation of lupus nephritis provide evidence of multiple biologically relevant lupus nephritis susceptibility loci.
| S-EPMC4243339 | biostudies-literature
Project description:Essentials Systemic lupus erythematosus (SLE) patients are at increased risk for premature CVD. Platelet activity, vascular dysfunction and carotid artery plaque are associated with FcγRIIA genotype in SLE. FcγRIIA genotype was not associated with platelet activity or carotid plaque in healthy controls. FcγRIIA represents a link that connects platelet activity, vascular health and CVD in SLE. SUMMARY: Background Systemic lupus erythematosus (SLE) is a complex autoimmune disease associated with an elevated risk of premature cardiovascular disease. Platelets express receptors contributing to inflammation and immunity, including FcγRIIA, the low affinity receptor of the Fc portion of IgG antibodies. The variation at a single amino acid substitution, H131R, in the extracellular binding domain alters the affinity for IgG, which may account for individual variation in platelet activity and platelet-mediated disease. Objectives This study was performed to investigate the association between FcγRIIA genotype, preclinical atherosclerosis, platelet reactivity and vascular health. Methods FcγRIIA was genotyped in 80 SLE patients and 30 healthy controls. Carotid ultrasound plaque, soluble E-selectin and platelet aggregability were evaluated in SLE and matched controls. Results Carotid plaque was significantly more prevalent in SLE patients carrying a variant allele compared to those with a homozygous ancestral allele (58% vs. 25%, P = 0.04). In contrast, prevalent carotid plaque was not associated with genotype in controls. Consistently, SLE variant FcγRIIA carriers vs. ancestral allele carriers had a significant increase in the levels of soluble E-selectin, which was not observed in controls. Monocyte and leukocyte-platelet aggregation and platelet aggregation in response to submaximal agonist stimulation were significantly elevated in SLE patients with the variant vs. ancestral genotype. Conclusions Carotid ultrasound plaque, soluble E-selectin levels and platelet activity were more frequently prevalent in SLE patients carrying variant FcγRIIA. The interplay between FcγRIIA-mediated platelet activation and endothelial cells might represent a mechanism underlying the pathogenesis of cardiovascular disease in SLE patients.
| S-EPMC6440197 | biostudies-literature
Project description:Renal infiltration with mononuclear cells is associated with poor prognosis in systemic lupus erythematosus. A renal macrophage/dendritic cell signature is associated with the onset of nephritis in NZB/W mice, and immune-modulating therapies can reverse this signature and the associated renal damage despite ongoing immune complex deposition. In nephritic NZB/W mice, renal F4/80(hi)/CD11c(int) macrophages are located throughout the interstitium, whereas F4/80(lo)/CD11c(hi) dendritic cells accumulate in perivascular lymphoid aggregates. We show here that F4/80(hi)/CD11c(int) renal macrophages have a Gr1(lo)/Ly6C(lo)/VLA4(lo)/MHCII(hi)/CD43(lo)/CD62L(lo) phenotype different from that described for inflammatory macrophages. At nephritis onset, F4/80(hi)/CD11c(int) cells upregulate cell surface CD11b, acquire cathepsin and matrix metalloproteinase activity, and accumulate large numbers of autophagocytic vacuoles; these changes reverse after the induction of remission. Latex bead labeling of peripheral blood Gr1(lo) monocytes indicates that these are the source of F4/80(hi)/CD11c(int) macrophages. CD11c(hi)/MHCII(lo) dendritic cells are found in the kidneys only after proteinuria onset, turnover rapidly, and disappear rapidly after remission induction. Gene expression profiling of the F4/80(hi)/CD11c(int) population displays increased expression of proinflammatory, regulatory, and tissue repair/degradation-associated genes at nephritis onset that reverses with remission induction. Our findings suggest that mononuclear phagocytes with an aberrant activation profile contribute to tissue damage in lupus nephritis by mediating both local inflammation and excessive tissue remodeling.
| S-EPMC3159403 | biostudies-literature
Project description:We report a rare case of dengue fever triggering systemic lupus erythematosus and lupus nephritis. The patient presented herself during a large outbreak of dengue fever in December 2012 in Maharashtra, India. The diagnosis of dengue fever was confirmed by the presence of NS-1 antigen during the first few days of febrile illness. Eight weeks later, kidney tissue biopsy studies revealed evidence of lupus nephritis on microscopic examination and immunofluorescence. The report interpreted it as focal proliferative glomerulonephritis and segmental sclerosis (Stage IIIC). The case was also found positive for perinuclear antineutrophil cytoplasmic antibodies by indirect immunofluorescence assay. An active and effective management of a case essentially calls for clear perception of differentiating dengue-induced lupus flare, antineutrophil cytoplasmic antibody-related nephropathy, and/or dengue-induced de-novo lupus disease. Dengue viremia may be the trigger for immune complex formation in patients who are predisposed to developing autoimmune diseases. The present case explains the importance of considering the diagnosis of dengue-related lupus nephritis as an atypical occurrence in appropriate situations, as in this case. It would not be improper to regard this escalating disease as an expanded feature of dengue.
| S-EPMC3818025 | biostudies-literature
Project description:ObjectiveTo validate clinical indices of lupus nephritis activity and damage when used in children against the criterion standard of kidney biopsy findings.MethodsIn 83 children requiring kidney biopsy, the Systemic Lupus Erythematosus Disease Activity Index renal domain (SLEDAI-R), British Isles Lupus Assessment Group index renal domain (BILAG-R), Systemic Lupus International Collaborating Clinics (SLICC) renal activity score (SLICC-RAS), and SLICC Damage Index renal domain (SDI-R) were measured. Fixed effects and logistic models were calculated to predict International Society of Nephrology/Renal Pathology Society (ISN/RPS) class; low-to-moderate versus high lupus nephritis activity (National Institutes of Health [NIH] activity index [AI]) score: ≤10 versus >10; tubulointerstitial activity index (TIAI) score: ≤5 versus >5; or the absence versus presence of lupus nephritis chronicity (NIH chronicity index) score: 0 versus ≥1.ResultsThere were 10, 50, and 23 patients with ISN/RPS class I/II, III/IV, and V, respectively. Scores of the clinical indices did not differentiate among patients by ISN/RPS class. The SLEDAI-R and SLICC-RAS but not the BILAG-R differed with lupus nephritis activity status defined by NIH-AI scores, while only the SLEDAI-R scores differed between lupus nephritis activity status based on TIAI scores. The sensitivity and specificity of the SDI-R to capture lupus nephritis chronicity was 23.5% and 91.7%, respectively. Despite being designed to measure lupus nephritis activity, SLICC-RAS and SLEDAI-R scores significantly differed with lupus nephritis chronicity status.ConclusionCurrent clinical indices of lupus nephritis fail to discriminate ISN/RPS class in children. Despite its shortcomings, the SLEDAI-R appears best for measuring lupus nephritis activity in a clinical setting. The SDI-R is a poor correlate of lupus nephritis chronicity.
| S-EPMC4720587 | biostudies-literature
Project description:ObjectiveTo examine the epidemiology of serious infections, a significant cause of morbidity and mortality in systemic lupus erythematosus (SLE), in a nationwide cohort of SLE and lupus nephritis (LN) patients.MethodsUsing the Medicaid Analytic eXtract database for the years 2000-2006, we identified patients ages 18-64 years who had SLE and the subset who had LN. We ascertained cases of serious hospitalized infections using validated algorithms, and we determined 30-day mortality rates. Poisson regression was used to calculate infection incidence rates and multivariable Cox proportional hazards models were used to calculate hazard ratios (HRs) for the first infection, adjusted for sociodemographic variables, medication use, and an SLE-specific risk adjustment index.ResultsWe identified 33,565 patients with SLE, 7,113 of whom had LN. There were 9,078 serious infections in 5,078 SLE patients and 3,494 infections in 1,825 LN patients. The infection incidence rate per 100 person-years was 10.8 in the SLE cohort and 23.9 in the LN subcohort. In adjusted models for the SLE cohort, we observed increased risks of infection in men as compared to women (HR 1.33 [95% confidence interval (95% CI) 1.20-1.47]), in blacks as compared to whites (HR 1.14 [95% CI 1.06-1.21]), and in users of glucocorticoids (HR 1.51 [95% CI 1.43-1.61]) and immunosuppressive drugs (HR 1.11 [95% CI 1.03-1.20]) as compared to never users. Hydroxychloroquine users had a reduced risk of infection as compared to never users (HR 0.73 [95% CI 0.68-0.77]). The 30-day mortality rate per 1,000 person-years among those hospitalized with infections was 21.4 in the SLE cohort and 38.6 in the LN subcohort.ConclusionIn this diverse, nationwide cohort of SLE patients, we observed a substantial burden of serious infections with many subsequent deaths, particularly among those with LN.
| S-EPMC4446132 | biostudies-literature
Project description:ObjectiveNeutrophil extracellular traps (NET) expose modified antigens for autoantibodies in vasculitis. Little is known about levels and removal pathways of NET in systemic lupus erythematosus (SLE), especially in lupus nephritis (LN). We determined circulating levels and defined NET removal in large subsets of patients with incident SLE (iSLE), some of whom had new-onset nephritis.MethodsSerum levels of NET (ELISA), DNase1/DNase1L3 (ELISA), and DNase activity (functional assay) were determined in 216 patients with iSLE [103 had incident LN (iLN)], in 50 patients with other primary glomerulonephritis, and in healthy controls. Ex vivo NET production by neutrophils purified from a random selection of patients was quantified as elastase/DNA release and by immunofluorescence techniques.ResultsSerum NET levels were very high in iSLE/iLN compared to all groups of controls and correlated with anti-dsDNA, C3-C4, and proteinuria; iLN had the highest levels. DNase activity was decreased in iLN compared to SLE (20% had one-half DNase activity) despite similar serum levels of DNase1/DNase1L3. In these cases, pretreatment of serum with protein A restored DNase efficiency; 1 patient was homozygous for a c.289_290delAC variant of DNASE1L3. Ex vivo NET production by neutrophils purified from LN, SLE, and normal controls was similar in all cases.ConclusionPatients with iLN have increased circulating NET and reduced DNase activity, the latter being explained by the presence of inhibitory substances in circulation and/or by rare DNase1L3 mutations. Accumulation of NET derives from a multifactorial mechanism, and is associated and may contribute to disease severity in SLE, in particular to renal lesions. (Clinical trial registration: The Zeus study was registered at ClinicalTrials.gov, study number NCT02403115).
| S-EPMC6917988 | biostudies-literature
Project description:ObjectiveSystemic lupus erythematosus (SLE) is characterized by widespread organ inflammation. Metformin, commonly used for diabetes mellitus type 2, has been explored for its anti-inflammatory potential in SLE. This study investigates the association of metformin use on renal and cardiovascular outcomes in patients with SLE.MethodsThis is a retrospective study. We used the multicenter research network (TriNetX) database from 88 health care organizations globally. Patients with SLE aged 18 and above, admitted between January 1, 2014, and April 21, 2024, were included. Propensity score matching compared patients with SLE on metformin with those not on metformin, considering demographics, laboratory results, comorbidities, and baseline medication use. The study assessed outcomes, including lupus nephritis (LN), chronic kidney disease (CKD), and major adverse cardiovascular events (MACEs) at one and five years after SLE diagnosis.ResultsWe identified 9,178 patients with SLE on metformin and 78,983 patients with SLE not on metformin. After propensity score matching, patients with SLE on metformin had higher levels of hemoglobin A1C, whereas patients not on metformin had higher levels of urea nitrogen. When comparing both groups, the risk of developing LN (risk ratio [RR] = 1.70 [1.17-2.41]; P = 0.004), CKD (RR = 1.27 [1.07-1.52]; P = 0.007), and MACEs (RR = 1.21 [1.00-1.46]; P = 0.04) was significantly higher among patients not on metformin at one year after SLE diagnosis. After five years, the risk of LN and CKD was also higher in patients with SLE not on metformin. MACE risk was no longer significant after five years of diagnosis between both groups.ConclusionPatients with SLE not on metformin have a higher risk of developing LN, CKD, and MACEs compared with patients treated with metformin. Metformin's anti-inflammatory potential offers promise as a complementary therapy for SLE. Nonetheless, further research and clinical trials are needed to clarify its mechanisms, optimal dosage, and long-term effects.
| S-EPMC11319915 | biostudies-literature