Anna Broder

Inhibition of the TWEAK/Fn14 pathway attenuates renal disease in nephrotoxic serum nephritis

Previously it was shown that the TNF superfamily member TWEAK (TNFSF12) acts through its receptor, Fn14, to promote proinflammatory responses in kidney cells, including the production of MCP-1, RANTES, IP-10 and KC. In addition, the TWEAK/Fn14 pathway promotes mesangial cell proliferation, vascular cell activation, and renal cell death. To study the relevance of the TWEAK/Fn14 pathway in the pathogenesis of antibody-induced nephritis using the mouse model of nephrotoxic serum nephritis (NTN), we induced NTN by passive transfer of rabbit anti-glomerular antibodies into Fn14 knockout (KO) and wild type (WT) mice. Severe proteinuria as well as renal histopathology were induced in WT but not in Fn14 KO mice. Similarly, a pharmacologic approach of anti-TWEAK mAb administration into WT mice in the NTN model significantly ameliorated proteinuria and improved kidney histology. Anti-TWEAK treatment did not affect the generation of mouse anti-rabbit antibodies; however, within the kidney there was a significant decrease in glomerular immunoglobulin deposition, as well as macrophage infiltrates and tubulointerstitial fibrosis. The mechanism of action is most likely due to reductions in downstream targets of TWEAK/Fn14 signaling, including reduced renal expression of MCP-1, VCAM-1, IP-10, RANTES as well as Fn14 itself, and other molecular pathways associated with fibrosis in anti-TWEAK treated mice. Thus, TWEAK/Fn14 interactions are instrumental in the pathogenesis of nephritis in the NTN model, apparently mediating a cascade of pathologic events locally in the kidney rather than by impacting the systemic immune response. Disrupting TWEAK/Fn14 interactions may be an innovative kidney-protective approach for the treatment of lupus nephritis and other antibody-induced renal diseases.

Hydroxychloroquine Use Is Associated with Lower Odds of Persistently Positive Antiphospholipid Antibodies and/or Lupus Anticoagulant in Systemic Lupus Erythematosus

Objective. Antiphospholipid antibodies (aPL) play an active role in the pathogenesis of the antiphospholipid syndrome (APS). Primary prevention in APS may be aimed at decreasing existing elevated aPL levels, or preventing high aPL titers and/or lupus anticoagulant (LAC) from developing in the first place. Hydroxychloroquine (HCQ) has been shown in retrospective studies to decrease aPL titers in laboratory studies, and to decrease thrombosis risk in patients with systemic lupus erythematosus (SLE). We investigated an association between HCQ use and persistent aPL and/or LAC in SLE. Methods. We identified all patients over 21 years old with SLE from an urban tertiary care center who had aPL and LAC measured on at least 2 occasions at least 12 weeks apart. We defined the presence of persistent LAC+ and/or at least 1 aPL ≥ 40 U [immunoglobulin A (IgA), IgG, or IgM] as the main outcome variable. Results. Among 90 patients included in the study, 17 (19%) had persistent LAC+ and/or at least 1 aPL ≥ 40 U. HCQ use was associated with significantly lower odds of having persistent LAC+ and/or aPL ≥ 40 U (OR 0.21, 95% CI 0.05, 0.79, p = 0.02), adjusted for age, ethnicity, and sex. Conclusion. This is the first study to show that HCQ use is associated with lower odds of having persistently positive LAC and/or aPL. Data from this study provide a basis for the design of future prospective studies investigating the role of HCQ in primary and secondary prevention of APS.

Higher Rates and Clustering of Abnormal Lipids, Obesity, and Diabetes Mellitus in Psoriatic Arthritis Compared With Rheumatoid Arthritis

We compared the prevalence and the clustering of the metabolic syndrome (MetS) components (obese body mass index [BMI; ≥30 kg/m2], hypertriglyceridemia, low high‐density lipids, hypertension, and diabetes mellitus) in patients with psoriatic arthritis (PsA) and rheumatoid arthritis (RA) in the Consortium of Rheumatology Researchers of North America (CORRONA) Registry.

The constant region contributes to the antigenic specificity and renal pathogenicity of murine anti-DNA antibodies

Affinity for DNA and cross-reactivity with renal antigens are associated with enhanced renal pathogenicity of lupus autoantibodies. In addition, certain IgG subclasses are enriched in nephritic kidneys, suggesting that isotype may determine the outcome of antibody binding to renal antigens. To investigate if the isotype of DNA antibodies affects renal pathogenicity by influencing antigen binding, we derived IgM, IgG1, IgG2b and IgG2a forms of the PL9-11 antibody (IgG3 anti-DNA) by in vitro class switching or PCR cloning. The affinity and specificity of PL9-11 antibodies for nuclear and renal antigens were analyzed using ELISA, Western blotting, surface plasmon resonance (SPR), binding to mesangial cells, and glomerular proteome arrays. Renal deposition and pathogenicity were assayed in mice injected with PL9-11 hybridomas. We found that PL9-11 and its isotype-switched variants had differential binding to DNA and chromatin (IgG3>IgG2a>IgG1>IgG2b>IgM) by direct and competition ELISA, and SPR. In contrast, in binding to laminin and collagen IV the IgG2a isotype actually had the highest affinity. Differences in affinity of PL9-11 antibodies for renal antigens were mirrored in analysis of specificity for glomeruli, and were associated with significant differences in renal pathogenicity in vivo and survival. Our novel findings indicate that the constant region plays an important role in the nephritogenicity of antibodies to DNA by affecting immunoglobulin affinity and specificity. Increased binding to multiple glomerular and/or nuclear antigens may contribute to the renal pathogenicity of anti-DNA antibodies of the IgG2a and IgG3 isotype. Finally, class switch recombination may be another mechanism by which B cell autoreactivity is generated.

Disease-specific definitions of vitamin D deficiency need to be established in autoimmune and non-autoimmune chronic diseases: a retrospective comparison of three chronic diseases

IntroductionWe compared the odds of vitamin D deficiency in three chronic diseases: systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and type 2 diabetes (T2DM), adjusting for medications, demographics, and laboratory parameters, common to all three diseases. We also designed multivariate models to determine whether different factors are associated with vitamin D deficiency in different racial/ethnic groups.MethodsWe identified all patients with non-overlapping diagnoses of SLE, RA, and T2DM, with 25-hydroxyvitamin D (25OHD) levels measured between 2000 and 2009. Vitamin D deficiency was defined as 25OHD levels <20 ng/ml, based on previously established definitions. Race/ethnicity was analyzed as African-American non-Hispanic (African-American), Hispanic non-African-American (Hispanic), and Other based on self report.ResultsWe included 3,914 patients in the final analysis: 123 SLE, 100 RA, and 3,691 T2DM. Among African-Americans the frequency of vitamin D deficiency was 59% in SLE, 47% in RA, and 67% in T2DM. Among Hispanics the frequency of vitamin D deficiency was 67% in SLE, 50% in RA, and 59% in T2DM. Compared with the SLE group, the adjusted odds ratio of vitamin D deficiency was 1.1, 95% CI (0.62, 2.1) in the RA group, and 2.0, 95% CI (1.3, 3.1) in the T2DM group. In the multivariate analysis, older age, higher serum calcium and bisphosphonate therapy were associated with a lower odds of vitamin D deficiency in all three racial/ethnic groups: 1,330 African-American, 1,257 Hispanic, and 1,100 Other. T2DM, serum creatinine, and vitamin D supplementation were associated with vitamin D deficiency in some, but not all, racial/ethnic groups.ConclusionsVitamin D deficiency is highly prevalent in our patients with SLE, RA, and T2DM. While the odds of vitamin D deficiency are similar in RA and SLE patients in a multivariate analysis, T2DM patients have much higher odds of being vitamin D deficient. Different demographic and laboratory factors may be associated with vitamin D deficiency within different racial/ethnic groups. Therefore, disease-specific and race/ethnicity-specific definitions of vitamin D deficiency need to be established in future studies in order to define goals of vitamin D replacement in patients with autoimmune and non-autoimmune chronic diseases.

Dendritic cells: an important link between antiphospholipid antibodies, endothelial dysfunction, and atherosclerosis in autoimmune and non-autoimmune diseases.

The presence of dendritic cells, antigen-presenting cells that link innate and adaptive immunity, is necessary to generate and maintain the production of antiphospholipid antibodies in response to exposed intracellular phospholipids on the outer surface of apoptotic cells. In turn, antiphospholipid antibodies enhance dendritic cell-induced inflammatory and proatherogenic responses in a number of conditions that are associated with accelerated atherosclerosis, including diabetes, chronic kidney disease, periodontal infections, and aging. While altering dendritic cells by modifying the ubiquitin-proteasome system enhances antiphospholipid antibody production and leads to development of accelerated atherosclerosis and autoimmune features, inducing tolerance by dendritic cell manipulation leads to decreased atherosclerosis and thrombosis. Therefore, further translational studies are needed to understand the interplay between dendritic cells and antiphospholipid antibodies, and to develop potential new therapies for antiphospholipid syndrome and atherosclerosis. Here we review current experimental and translational studies that have examined the role of dendritic cells in antiphospholipid antibody formation and in antiphospholipid-associated atherosclerosis and thrombosis.

Improving outcomes in patients with lupus and end-stage renal disease.

The development of lupus‐related end‐stage renal disease (ESRD) confers the highest mortality rates among individuals with lupus. Lupus‐related ESRD is also associated with higher morbidity and mortality rates compared with non‐lupus ESRD. We review the evidence that persistent lupus activity, hypercoagulability, and continuing immunosuppression may contribute to unfavorable outcomes in dialysis and renal transplantation among lupus patients. Robust epidemiologic studies are needed to develop individualized evidence‐based approaches to treating lupus‐related ESRD. In the meantime, managing lupus‐related ESRD presents a significant challenge for clinicians and requires a team approach involving nephrologists and rheumatologists. Goals of therapy after developing ESRD should include continuing monitoring of lupus activity, minimizing corticosteroid exposure, and choosing the most appropriate renal replacement therapy based on patients risk profile and quality‐of‐life considerations.

Undertreatment of disease activity in systemic lupus erythematosus patients with endstage renal failure is associated with increased all-cause mortality.

Objective. In a cohort of systemic lupus erythematosus (SLE) patients with endstage renal failure, to evaluate whether continuing rheumatology followup visits and immunosuppressive therapy after starting renal replacement were associated with increased survival. Methods. We identified all SLE patients over 21 years old who started renal replacement therapy between 2005 and 2011 at an urban tertiary care center. Mortality data were obtained using in-hospital records and the US Social Security Death Index database. Results. We identified 80 SLE patients undergoing renal replacement therapy. Twenty-two patients (28%) were followed in rheumatology clinics frequently (2 or more visits per year) after starting renal replacement therapy, and 58 patients (72%) were followed infrequently (fewer than 2 visits per year). Survival rates were significantly higher in transplant patients compared with dialysis patients. Patients with SLE followed frequently after starting dialysis had significantly higher 4-year survival rates compared with patients followed infrequently after starting dialysis (log-rank p = 0.03). In the Cox proportional hazards model, treatment with prednisone alone or with no medication was associated with a hazard ratio (HR) of death = 6.1 (95% CI 1.1, 34; p = 0.04) and HR = 13 (95% CI 1.5, 106; p = 0.02), respectively, compared with patients treated with a combination of immunosuppressive therapy with or without prednisone, adjusted for age at SLE diagnosis, sex, transplant status, and the frequency of rheumatology visits after the development of endstage renal failure. Conclusion. Active disease in patients with SLE undergoing renal replacement therapy may be underrecognized and undertreated, leading to increased mortality.

High antiphospholipid antibody levels are associated with statin use and may reflect chronic endothelial damage in non-autoimmune thrombosis: cross-sectional study

Objective Persistently elevated antiphospholipid antibodies and positive lupus anticoagulant (LAC) are associated with an increased risk of thrombosis. The objective of this study was to explore whether antiphospholipid antibody and/or LAC positivity were associated with the traditional risk factors for thrombosis or with medication use in patients without autoimmune diseases hospitalised with arterial or venous thrombosis. Design Cross-sectional study. Setting Montefiore Medical Center, a large urban tertiary care centre. Patients 270 patients (93 with deep vein thrombosis (DVT) or pulmonary embolism (PE), and 177 with non-haemorrhagic stroke (cerebrovascular accident (CVA)) admitted between January 2006 and December 2010 with a discharge diagnosis of either DVT, PE or CVA, who had LAC and antiphospholipid antibodies measured within 6 months from their index admission. Patients with lupus or antiphospholipid syndrome were excluded. Main Outcome Measures The main dependent variable was antiphospholipid antibodies of 40 units or greater (antiphospholipid antibody positivity) and/or LAC positivity. Independent variables were traditional thrombosis risk factors, statin use, aspirin use and warfarin use. Results 31 (11%) patients were LAC positive and/or antiphospholipid antibody positive. None of the traditional risk factors at the time of DVT/PE/CVA was associated with antiphospholipid antibody positivity. Current statin use was associated with an OR of 3.2 (95% CI 1.3 to 7.9, p=0.01) of antiphospholipid antibody positivity, adjusted for age, ethnicity and gender. Aspirin or warfarin use was not associated with antiphospholipid antibody levels. Conclusion If statin therapy reflects the history of previous hyperlipidaemia, high levels of antiphospholipid antibodies may be a marker for earlier endothelial damage caused by hyperlipidaemia.

A Comparison of Malignancy Incidence among Psoriatic and Rheumatoid Arthritis Patients in a Large US Cohort

To compare the incidence rates of malignancy among patients with psoriatic arthritis (PsA) and patients with rheumatoid arthritis (RA) in the Consortium of Rheumatology Researchers of North America (CORRONA) registry.