Given the early onset of neuropsychiatric disease and the potential response to immunosuppressive therapy, neuropsychiatric disease is considered a primary disease manifestation in SLE. However, the pathogenesis is not fully understood and optimal treatment has yet to be determined. TWEAK is a TNF family ligand that mediates pleotropic effects through its receptor Fn14, including the stimulation of inflammatory cytokines by astrocytes, endothelial cells, and other non-hematopeotic cell types, and induction of neuronal death. Furthermore, TWEAK-inducible mediators are implicated in neuropsychiatric lupus. Thus, we hypothesized that the TWEAK/Fn14 pathway may be involved in the pathogenesis of neuropsychiatric SLE. We generated MRL-lpr/lpr (MRL/lpr) mice deficient for Fn14, the sole known signaling receptor for TWEAK. Neuropsychiatric disease was compared in age- and gender-matched MRL/lpr Fn14 wild type (WT) and knockout (KO) mice, using a comprehensive battery of neurobehavioral tests. We found that MRL/lpr Fn14WT mice displayed profound depression-like behavior as seen by increased immobility in a forced swim test and loss of preference for sweetened fluids, which were significantly ameliorated in Fn14KO mice. Similarly, MRL/lpr Fn14WT mice had impaired cognition, and this was significantly improved in Fn14KO mice. To determine the mechanism by which Fn14 deficiency ameliorates neuropsychiatric disease, we assessed the serum levels of autoantibodies and local expression of cytokines in the cortex and hippocampus of lupus mice. No significant differences were found in the serum levels of antibodies to nuclear antigens, or autoantibodies specifically associated with neuropsychiatric disease, between MRL/lpr Fn14WT and KO mice. However, MRL/lpr Fn14KO mice had significantly decreased brain expression of RANTES, C3, and other proinflammatory mediators. Furthermore, MRL/lpr Fn14KO mice displayed improved blood brain barrier integrity. In conclusion, several central manifestations of neuropsychiatric lupus, including depression-like behavior and altered cognition, are normalized in MRL/lpr mice lacking Fn14. Our results are the first to indicate a role for the TWEAK/Fn14 pathway in the pathogenesis of neuropsychiatric lupus, and suggest this ligand-receptor pair as a potential therapeutic target for a common and dangerous disease manifestation.
Systemic lupus erythematosus (SLE); neuropsychiatric lupus; TWEAK; Fn14
To determine the necessity for any individual BAFF receptor in the development of SLE.
Bcma, Taci, and Br3 null mutations were introgressed into NZM 2328 mice. NZM.Bcma−/−, NZM.Taci−/−, and NZM.Br3−/− mice were evaluated for lymphocyte phenotype and BAFF receptor expression by flow cytometry, B cell responsiveness to BAFF by in vitro culture, serum BAFF and total IgG and IgG anti-dsDNA levels by ELISA, renal immunopathology by immunofluorescence and histopathology, and clinical disease.
NZM.Bcma−/−, NZM.Taci−/−, and NZM.Br3−/− mice failed to surface-express BCMA, TACI, and BR3, respectively. Transitional and follicular B cells from NZM.Br3−/− mice were much less responsive to BAFF than the corresponding cells from wild-type (WT), NZM.Bcma−/−, or NZM.Taci−/− mice. In comparison to WT mice, NZM.Bcma−/− and NZM.Taci−/− mice harbored increased spleen B cells, T cells, and plasma cells (PC), whereas serum total IgG and IgG anti-dsDNA levels were similar. Despite their paucity of B cells, NZM.Br3−/− mice harbored increased T cells and WT-like numbers of PC and levels of IgG anti-dsDNA. Serum BAFF levels were increased in NZM.Taci−/− and NZM.Br3−/− mice but were decreased in NZM.Bcma−/− mice. Despite their phenotypic differences, renal immunopathology and clinical disease in NZM.Bcma−/−, NZM.Taci−/−, and NZM.Br3−/− mice were at least as severe as in WT mice.
Any single BAFF receptor, including BR3, is dispensable to development of SLE in NZM mice. Development of disease in NZM.Br3−/− mice demonstrates that BAFF/BCMA and/or BAFF/TACI interactions contribute to SLE and that profound, life-long reduction in B cells does not guarantee protection from SLE.
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, in patients with psoriatic arthritis (PsA) and rheumatoid arthritis (RA) in the Consortium of Rheumatology Researchers of North America (CORRONA) registry.
We included CORRONA participants with the rheumatologist-confirmed clinical diagnoses of PsA and RA with complete data. We used a modified definition of MetS that did not include insulin resistance, waist circumference or blood pressure measurements. Logistic regression models were adjusted for age, sex and race.
In the overall CORRONA population, the rates of diabetes and obesity were significantly higher in PsA compared with RA. In 294 PsA and 1162 RA participants who had lipids measured, the overall prevalence of MetS in PsA vs. RA was 27% vs. 19%. The odds ratio (OR) of MetS in PsA vs. RA was 1.44 (95% confidence interval (CI) 1.05 to 1.96), p=0.02. The prevalence of hypertriglyceridemia was higher in PsA compared with RA, 38% vs. 28%, OR 1.51 (95% CI 1.15 to 1.98), p=0.003. The prevalence of type II diabetes was also higher in PsA compared with RA (15% vs. 11%), OR 1.56 (95% CI 1.07 to 2.28), p=0.02, in the adjusted model. Similarly, higher rates of hypertriglyceridemia and diabetes were observed in the subgroup of PsA and RA patients with obese BMI.
PsA is associated with the higher rates of obesity, diabetes, and hypertriglyceridemia, compared with RA.
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 patient’s risk profile and quality of life considerations.
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.
dendritic cells; antiphospholipid antibodies; atherosclerosis; antiphospholipid syndrome
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.
Systemic lupus erythematosus (SLE); Lupus nephritis; Anti-DNA antibodies; Isotype switching
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.
Systemic lupus erythematosus (SLE); Nephrotoxic Serum Nephritis; TWEAK; Fn14
To evaluate whether continuing rheumatology follow-up visits and immunosuppressive therapy after starting renal replacement were associated with increased survival in lupus patients with end stage renal failure.
We identified all lupus patients over 21 years old who started renal replacement therapy between 2005 and 2011 at an urban tertiary care center. Mortality data was obtained using in-hospital records and the Social Security Death Index database.
We identified 80 lupus patients on 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. However, SLE patients 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. Furthermore, in the Cox proportional hazards model, treatment with prednisone alone or with no medication was associated with a hazard ratio (HR) of death of 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, gender, transplant status and the frequency of rheumatology visits after the development of end stage renal failure.
Active disease in lupus patients on renal replacement therapy may be under-recognized and under-treated, leading to increased mortality.
Lupus Erythematosus; Systemic; Lupus nephritis; Kidney Failure; Chronic; Mortality
Antiphospholipid antibodies (aPL Abs) play an active role in the pathogenesis of the antiphospholipid syndrome (APLS). Primary prevention in APLS may be aimed at decreasing existing elevated aPL Ab levels, or preventing high aPL titers and/or lupus anticoagulant (LAC) from developing in the first place. Hydroxychloroquine (HCQ) has been shown to decrease aPL titers in laboratory studies, and to decrease thrombosis risk in systemic lupus erythematosus (SLE) patients in retrospective studies. We investigated an association between HCQ use and persistent aPL Abs and/or LAC in SLE.
We identified all patients over 21 years old with SLE, from an urban tertiary care center, who had aPL Abs and LAC measured on at least 2 occasions, at least 12 weeks apart. We defined the presence of persistent LAC+ and/or at least one aPL Ab ≥ 40 units (IgA, IgG or IgM) as the main outcome variable.
Among 90 patients included in the study, 17 (19%) had persistent LAC+ and/or at least one aPL Ab ≥ 40 units. HCQ use was associated with significantly lower odds of having persistent LAC+ and/or aPL Abs ≥ 40 U, OR 0.21 (95% CI 0.05, 0.79) p=0.02, adjusted for age, ethnicity, and gender.
This is the first study to show that HCQ use is associated with lower odds of having persistently positive LAC and/or aPL Abs. Data from this study provides a basis for the design of future prospective studies investigating the role of HCQ in primary and secondary prevention of APLS.
Lupus Erythematosus, Systemic; Antiphospholipid Antibodies; Lupus Anticoagulant; Hydroxychloroquine
Persistently elevated antiphospholipid antibodies (aPL Ab) and positive lupus anticoagulant (LAC) are associated with an increased risk of thrombosis. Our objective was to explore whether aPL Ab and/or LAC positivity were associated with the traditional risk factors for thrombosis or with medication use in patients without autoimmune diseases hospitalized with arterial or venous thrombosis.
Montefiore Medical Center, a large urban tertiary care center
Two hundred and seventy patients (93 with deep vein thrombosis (DVT) or pulmonary embolism (PE), and 177 with non-hemorrhagic stroke (CVA)) admitted between January 2006 and December 2010 with a discharge diagnosis of either DVT, PE or CVA, who had LAC and aPL Abs measured within six months from their index admission. We excluded patients with lupus or antiphospholipid syndrome.
Main Outcome Measures
The main dependant variable was aPL Ab ≥ 40 units (aPL Ab+) and/or LAC+. Independent variables: traditional thrombosis risk factors, statin use, aspirin use, and warfarin use.
Thirty one (11%) patients were LAC+ and/or aPL Ab+ (aPL/LAC+). None of the traditional risk factors at the time of DVT/PE/CVA was associated with aPL/LAC+. Current statin use was associated with an OR of 3.2 (95% CI 1.3, 7.9, p = 0.01) of aPL/LAC+, adjusted for age, ethnicity and gender. Aspirin or warfarin use was not associated with aPL Ab levels.
If statin therapy reflects the history of prior hyperlipidemia, high levels of aPL Abs may be a marker for prior endothelial damage caused by hyperlipidemia.
Antiphospholipid antibodies; statins; endothelial damage; thrombosis
There is significant unmet need in the treatment of lupus nephritis (LN) patients. In this review, we highlight the role of the TWEAK/Fn14 pathway in mediating key pathologic processes underlying LN involving both glomerular and tubular injury, and thus the potential for renal protection via blockade of this pathway. The specific pathological mechanisms of TWEAK – namely promoting inflammation, renal cell proliferation and apoptosis, vascular activation and fibrosis – are described, with supporting data from animal models and in vitro systems. Furthermore, we detail the translational relevance of these mechanisms to clinical readouts in human LN. We present the opportunity for an anti-TWEAK therapeutic as a renal protective agent to improve efficacy relative to current standard of care treatments hopefully without increased safety risk, and highlight a phase II trial with BIIB023, an anti-TWEAK neutralizing antibody, designed to assess efficacy in LN patients. Taken together, targeting the TWEAK/Fn14 axis represents a potential new therapeutic paradigm for achieving renal protection in LN patients.
To determine the role for APRIL in the development of SLE.
Wild-type (WT) NZM 2328, NZM.April-/-, NZM.Baff-/-, and NZM.Baff-/-.April-/- mice were evaluated for lymphocyte phenotype by flow cytometry, for serum total IgG and IgG autoantibody levels by ELISA, for glomerular deposition of IgG and C3 by immunofluorescence, for renal histopathology, and for clinical disease (severe proteinuria).
In comparison to WT mice, NZM.April-/- mice harbored increased spleen B cells, T cells, and plasma cells (PC); increased serum levels of IgG anti-chromatin antibodies; and decreased numbers of bone marrow (BM) PC. In addition, glomerular deposition of IgG and C3 was similar in NZM.April-/- and WT mice; renal histopathology tended to be more severe in NZM.April-/- mice than in WT mice; and development of clinical disease was identical in NZM.April-/- and WT mice. BM (but not spleen) PC and serum IgG anti-chromatin and anti-dsDNA antibody levels were lower in NZM.Baff-/-.April-/- mice than in NZM.Baff-/- mice, whereas renal immunopathology in each cohort was equally mild.
APRIL is dispensable for development of full-blown SLE in NZM mice. Moreover, the elimination of both APRIL and BAFF has no discernable effect on development of renal immunopathology or clinical disease beyond that of elimination of BAFF alone. The reduction in BM PC in hosts doubly-deficient in APRIL and BAFF beyond that in hosts deficient only in BAFF raises concern that combined antagonism of APRIL and BAFF may lead to greater immunosuppression without concomitant increase in therapeutic efficacy.
The mechanism by which anti-DNA antibodies mediate lupus nephritis has yet to be conclusively determined. Previously, we found that treatment of mesangial cells with anti-DNA antibodies induced high expression of Neutrophil Gelatinase Associated Lipocalin (NGAL), an iron-binding protein upregulated in response to kidney injury. However, whether NGAL is instrumental in pathogenesis, induced as part of repair, or irrelevant to damage/repair pathways, is not known.
To investigate the role of NGAL in antibody-mediated nephritis, we induced nephrotoxic nephritis by passive antibody transfer to B6 or 129 mice. To determine if NGAL upregulation is instrumental, we compared the severity of renal damage in NGAL wild-type and knock-out mice following induction of nephrotoxic nephritis.
We found that kidney NGAL expression, as well as urinary NGAL levels, were significantly increased in nephrotoxic nephritis as compared to control injected mice. Tight correlations were observed between NGAL expression, renal histopathology, and urinary NGAL excretion. NGAL knock-out mice had attenuated proteinuria and improved renal histopathology as compared to wild-type mice. Similarly, following nephritis induction, NGAL injection significantly exacerbated nephritis and decreased survival. NGAL induces apoptosis via caspase-3 activation, and upregulates inflammatory gene expression in kidney cells in vitro and when injected in vivo.
We conclude that kidney binding of pathogenic antibodies stimulates local expression of NGAL, which plays a crucial role in the pathogenesis of nephritis via promotion of inflammation and apoptosis. NGAL blockade may be a novel therapeutic approach for the treatment of nephritis mediated by pathogenic antibodies, including anti-GBM disease and lupus nephritis.
Gait Velocity (GV) is predictive of hospitalizations and mortality in the elderly. In the US, elderly African Americans have higher rates of physical disability compared to Caucasians. Few studies have investigated if there are racial differences in GV in the elderly.
We performed a cross sectional analysis to investigate racial differences in GV.
Participants were part of the Einstein Aging Study, a longitudinal study of community-residing elderly in the Bronx, NY. They were recruited using Medicare and voter registration records. Records of 213 participants were analyzed.
Demographics, medical history, the Geriatric Depression Scale, the Blessed Information Memory Concentration Test, and the Total Pain Index (TPI) were collected. GV was measured using the GAITrite® mat.
We included 157 Caucasians and 56 African Americans. Caucasians were older (median 79.9y v 75.5y, p<0.01), more educated (median 14y v 12y, p<0.01) and had lower BMIs (mean 26.9±4.3 v 28.9±6.4, p=0.03). African Americans had higher proportions of female participants (80.4% v 59.9%, p<0.01) and diabetes (28.6% v 13.4%, p=0.01). Neither group had significantly higher pain levels. African Americans had a significantly slower GV (mean 90.2±17.9 v 99.1±20.1 cm/sec, p<0.01). This difference persists despite adjusting for multiple covariates. A 7.79 cm /sec slower gait speed in African Americans versus Caucasians was not explained by differences in common factors known to influence gait.
Differences in GV persist between African Americans and Caucasians despite adjusting for many confounders. Increases of just 10cm/sec are associated with reduced mortality. Further studies are needed to evaluate if there are modifiable risk factors that potentially explain this difference and if an intervention could reduce the discrepancy between the groups.
gait velocity; health disparities; elderly; physical function
The TNF ligand family member TWEAK exists as membrane and soluble forms and is involved in the regulation of various human inflammatory pathologies, through binding to its main receptor, Fn14. We have shown that the soluble form of TWEAK has a pro-neuroinflammatory effect in an animal model of multiple sclerosis and we further demonstrated that blocking TWEAK activity during the recruitment phase of immune cells across the blood brain barrier (BBB) was protective in this model. It is now well established that endothelial cells in the periphery and astrocytes in the central nervous system (CNS) are targets of TWEAK. Moreover, it has been shown by others that, when injected into mice brains, TWEAK disrupts the architecture of the BBB and induces expression of matrix metalloproteinase-9 (MMP-9) in the brain. Nevertheless, the mechanisms involved in such conditions are complex and remain to be explored, especially because there is a lack of data concerning the TWEAK/Fn14 pathway in microvascular cerebral endothelial cells.
In this study, we used human cerebral microvascular endothelial cell (HCMEC) cultures as an in vitro model of the BBB to study the effects of soluble TWEAK on the properties and the integrity of the BBB model.
We showed that soluble TWEAK induces an inflammatory profile on HCMECs, especially by promoting secretion of cytokines, by modulating production and activation of MMP-9, and by expression of cell adhesion molecules. We also demonstrated that these effects of TWEAK are associated with increased permeability of the HCMEC monolayer in the in vitro BBB model.
Taken together, the data suggest a role for soluble TWEAK in BBB inflammation and in the promotion of BBB interactions with immune cells. These results support the contention that the TWEAK/Fn14 pathway could contribute at least to the endothelial steps of neuroinflammation.
CCL-2; hCMEC/D3; HMEC; IL-8; MMP-9; Neuroinflammation; TNFSF12; ZO-1
Patients with systemic lupus erythematosus (SLE) can experience acute neurological events such as seizures, cerebrovascular accidents, and delirium, psychiatric conditions including depression, anxiety, and psychosis, as well as memory loss and general cognitive decline. Neuropsychiatric SLE (NPSLE) occurs in between 30 and 40% of SLE patients, can constitute the initial patient presentation, and may occur outside the greater context of an SLE flare. Current efforts to elucidate the mechanistic underpinnings of NPSLE are focused on several different and potentially complementary pathways, including thrombosis, brain autoreactive antibodies, and complement deposition. Furthermore, significant effort is dedicated to understanding the contribution of neuroinflammation induced by TNF, IL-1, IL-6, and IFN-γ. More recent studies have pointed to a possible role for the TNF family ligand TWEAK in the pathogenesis of neuropsychiatric disease in human lupus patients, and in a murine model of this disease. The blood brain barrier (BBB) consists of tight junctions between endothelial cells (ECs) and astrocytic projections which regulate paracellular and transcellular flow into the central nervous system (CNS), respectively. Given the privileged environment of the CNS, an important question is whether and how the integrity of the BBB is compromised in NPSLE, and its potential pathogenic role. Evidence of BBB violation in NPSLE includes changes in the albumin quotient (Qalb) between plasma and cerebrospinal fluid, activation of brain ECs, and magnetic resonance imaging. This review summarizes the evidence implicating BBB damage as an important component in NPSLE development, occurring via damage to barrier integrity by environmental triggers such as infection and stress; cerebrovascular ischemia as result of a generally prothrombotic state; and immune mediated EC activation, mediated by antibodies and/or inflammatory cytokines. Additionally, new evidence supporting the role of TWEAK/Fn14 signaling in compromising the integrity of the BBB in lupus will be presented.
TWEAK; Fn14; blood brain barrier; neuropsychiatric lupus; MRL/lpr
Although renal pathology is highly predictive of the disease course in lupus nephritis, it cannot be performed serially because of its invasive nature and associated morbidity. The goal of this study is to investigate whether urinary levels of CXC ligand 16 (CXCL16), monocyte chemotactic protein-1 (MCP-1) or vascular cell adhesion molecule-1 (VCAM-1) in patients with lupus nephritis are predictive of particular features of renal pathology in renal biopsies obtained on the day of urine procurement.
CXCL16, MCP-1, and VCAM-1 levels were measured in urine samples from 74 lupus nephritis patients and 13 healthy volunteers. Of the patients enrolled, 24 patients had a concomitant kidney biopsy performed at the time of urine collection. In addition, patients with other renal diatheses were also included as controls.
All three molecules were elevated in the urine of systemic lupus erythematosus patients, although VCAM-1 (area under curve = 0.92) and MCP-1 (area under curve = 0.87) were best at distinguishing the systemic lupus erythematosus samples from the healthy controls, and were also most strongly associated with clinical disease severity and active renal disease. For patients in whom concurrent renal biopsies had also been performed, urine VCAM-1 exhibited the strongest association with the renal pathology activity index and glomerulonephritis class IV, although it correlated negatively with the chronicity index. Interestingly, urinary VCAM-1 was also elevated in anti-neutrophil cytoplasmic antibodies-associated glomerulonephritis, focal segmental glomerulosclerosis and membranous nephropathy but not in minimal-change disease.
Urinary VCAM-1 emerges as a reliable indicator of the activity:chronicity ratios that mark the underlying renal pathology in lupus nephritis. Since VCAM-1 is involved in the acute phase of inflammation when leukocytic infiltration is ongoing, longitudinal studies are warranted to establish whether tracking urine VCAM-1 levels may help monitor clinical and pathological disease activity over time.
The metabolic disturbances that underlie systemic lupus erythematosus are currently unknown. A metabolomic study was executed, comparing the sera of 20 SLE patients against that of healthy controls, using LC/MS and GC/MS platforms. Validation of key differences was performed using an independent cohort of 38 SLE patients and orthogonal assays. SLE sera showed evidence of profoundly dampened glycolysis, Krebs cycle, fatty acid β oxidation and amino acid metabolism, alluding to reduced energy biogenesis from all sources. Whereas long-chain fatty acids, including the n3 and n6 essential fatty acids, were significantly reduced, medium chain fatty acids and serum free fatty acids were elevated. The SLE metabolome exhibited profound lipid peroxidation, reflective of oxidative damage. Deficiencies were noted in the cellular anti-oxidant, glutathione, and all methyl group donors, including cysteine, methionine, and choline, as well as phosphocholines. The best discriminators of SLE included elevated lipid peroxidation products, MDA, gamma-glutamyl peptides, GGT, leukotriene B4 and 5-HETE. Importantly, similar elevations were not observed in another chronic inflammatory autoimmune disease, rheumatoid arthritis. To sum, comprehensive profiling of the SLE metabolome reveals evidence of heightened oxidative stress, inflammation, reduced energy generation, altered lipid profiles and a pro-thrombotic state. Resetting the SLE metabolome, either by targeting selected molecules or by supplementing the diet with essential fatty acids, vitamins and methyl group donors offers novel opportunities for disease modulation in this disabling systemic autoimmune ailment.
Renal involvement in patients with systemic lupus erythematosus in the form of severe lupus nephritis is associated with a significant burden of morbidity and mortality. Conventional laboratory biomarkers in current use have not been very successful in anticipating disease flares, predicting renal histology, or decreasing unwanted outcomes. Since early treatment is associated with improved clinical results, it is thus essential to identify new biomarkers with substantial predictive power to reduce the serious sequelae of this difficult to control lupus manifestation. Indeed, considerable efforts and progress have been made over the last few years in the search for novel biomarkers. Since urinary biomarkers are more easily obtainable with much less risk to the patient than repeat renal biopsies, and these may more accurately discern between renal disease and other organ manifestations than their serum counterparts, there has been tremendous interest in studying new candidate urine biomarkers. Below, we review several promising urinary biomarkers under investigation, including total proteinuria and microalbuminuria, urinary proteomic signatures, and the individual inflammatory mediators interleukin-6, vascular cell adhesion molecule-1, CXCL16, IP-10, and tumor necrosis factor-like weak inducer of apoptosis.
Biomarkers; Lupus nephritis; Urinary biomarkers; Proteomics; TWEAK; SLE
Systemic Lupus Erythematosus (SLE) typically affects females at far greater rates than males; however male SLE patients often have more severe disease than females. The gender disparities have been reported in clinical manifestations and in serological and hematological indices as well. In particular, SLE complicated with nephritis is more frequent in men than women, and several groups identified male gender as a risk factor for progression to renal failure. The specific differences in pathogenesis amongst genders have yet to be conclusively defined, though genetic, hormonal, and immune responses have been analyzed thus far. Further research is warranted to further elucidate these differences and permit the development of gender-tailored treatment regimens.
IFNα is a potent activator of innate and adaptive immunity, and its administration to pre-autoimmune (NZBxNZW)F1 mice promotes virulent systemic lupus erythematosus (SLE) disease. Given the known contributions of B cells and BAFF to SLE, we evaluated the ability of IFNα administration to induce disease in wild-type (WT), B cell-deficient, and BAFF-deficient NZM 2328 mice. Whereas WT mice rapidly developed proliferative glomerulonephritis (GN), marked proteinuria, and increased mortality in response to IFNα administration, B cell-deficient mice developed neither renal pathology nor clinical disease. Moreover, BAFF-deficient mice, despite developing limited glomerular IgG and C3 deposition, also remained free of histological GN and clinical disease. Strikingly, similar T cell expansion and serum IgG responses were observed in Adv-IFN-treated WT and BAFF-deficient mice despite their disparate pathological and clinical responses, whereas numbers of activated B cells increased in WT mice but not in BAFF-deficient mice. Nonetheless, B cell, plasma cell, and T cell infiltration of the kidneys in Adv-IFN-treated WT mice was similar to that in WT mice treated with Adv-control. Its ability to promote SLE disease in WT mice notwithstanding, IFNα administration failed to drive the preferential expansion of CD4+ memory T cells that occurs during the natural course of disease, and glomerular infiltration of macrophages failed to associate with development of disease. These results collectively suggest that therapeutic targeting in SLE of BAFF and/or B cells in SLE could be successful even in states of IFNα overexpression. Moreover, our results document important biological differences between IFNα-driven and spontaneous “natural” SLE disease.
rodent; systemic lupus erythematosus; cytokines
Antibodies of the IgG3 subclass have been implicated in the pathogenesis of the spontaneous glomerulonephritis observed in mice of the MRL/MpJ-Tnfrsf6lpr (MRL/lpr) inbred strain which have been widely studied as a model of systemic lupus erythematosus We have produced IgG3-deficient (-/-) mice with the MRL/lpr genetic background to determine whether IgG3 antibodies are necessary for or at least contributory to MRL/lpr-associated nephritis.
The gamma3 genotype (+/+ vs. +/- vs. -/-) did not appear to significantly affect serum titers of IgG auto-antibodies specific for double-stranded DNA (dsDNA) or α-actinin. However, while substantial serum titers of IgG3 auto-antibodies specific for double-stranded DNA (dsDNA) or α-actinin were seen in gamma3 +/+ mice, somewhat lower serum titers of these IgG3 auto-antibodies were found in gamma3 +/- mice, and gamma3 -/- mice exhibited baseline concentrations of these auto-antibodies. Analysis of immunoglobulins eluted from snap-frozen kidneys obtained from mice of all three gamma3 genotypes at ~18 weeks of age revealed much higher quantities of IgG in the kidneys from gamma3 +/+ than gamma3 -/- mice, and most IgG eluted from +/+ mice was IgG3. The serum creatinine levels in gamma3 +/+ mice substantially exceeded those of age-matched gamma3 -/- mice after ~21 weeks of age. Histopathological examination of kidneys from mice sacrificed at pre-determined ages also revealed more extensive glomerulosclerosis in gamma3 +/+ or +/- mice than in -/- mice beginning at 21 weeks of age. Survival analysis for IgG3-deficient and IgG3-producing MRL/lpr mice revealed that gamma3 -/- mice lived significantly longer (p = 0.0006) than either gamma3 +/- or +/+ mice. Spontaneous death appeared to be due to irreversible renal failure, because > 85% of glomeruli in kidneys from mice that died spontaneously were obliterated by glomerulosclerosis.
The available evidence suggests that IgG3 deficiency partially protects MRL/lpr mice against glomerulonephritis-associated morbidity and mortality by slowing or arresting the progression to glomerulosclerosis.
This article was reviewed by Pushpa Pandiyan, Irun Cohen, and Etienne Joly.