Genetic risk factors in lupus nephritis and IgA nephropathy--no support of an overlap

Association of <i>VEGF</i> gene rs699947 and rs2010963 polymorphisms with vascular endothelial growth factor levels in the blood serum of children with lupus nephritis

The growth factor genes VEGF and TGFB1 are involved in the normal functioning of the kidneys, and some polymorphic loci of these genes determine a genetic predisposition to the autoimmune diseases, including systemic lupus erythematosus (SLE) and its dangerous complication, lupus nephritis (LN). The products of these genes, in particular, the vascular endothelial growth factor protein and the transforming growth factor β1 protein are used in clinical practice as markers of endothelial dysfunction for early diagnosis of kidney pathology. However, the relationship between the expression of these proteins and the genotypes/alleles of the polymorphic loci of these genes has not been studied enough, which requires clarification of this issue for the child population of Belarus. In this work, we analyzed the associations of the TGFB1 (rs1800469) and VEGF (rs699947 and rs2010963) gene genotypes with the concentration of their products in the blood serum of patients with LN during exacerbation and remission of the disease. The study did not find a significant relationship between polymorphic variants of the TGFB1 gene (rs1800469) and levels of its product in the blood. An association has been established between the rs699947 and rs2010963 polymorphic variants of the VEGF gene and the serum concentration of the gene product in pediatric patients with LN during exacerbation. It was found that the homozygous minor genotype AA of the polymorphic locus rs699947 and the group of genotypes GC + CC containing at least one minor allele of the locus rs2010963 are associated with higher levels of the gene product in the blood serum of children with LN during disease exacerbation (p < 0.001 and p = 0.036, respectively). Thus, VEGF polymorphic variants associated with an increased concentration of the gene product in the blood serum during disease exacerbation can be considered as markers of the risk of disease exacerbation in patients with LN.

Quantitative planar array screen of 1000 proteins uncovers novel urinary protein biomarkers of lupus nephritis

OBJECTIVE

The goal of these studies is to discover novel urinary biomarkers of lupus nephritis (LN).

METHODS

Urine from systemic lupus erythematosus (SLE) patients was interrogated for 1000 proteins using a novel, quantitative planar protein microarray. Hits were validated in an independent SLE cohort with inactive, active non-renal (ANR) and active renal (AR) patients, in a cohort with concurrent renal biopsies, and in a longitudinal cohort. Single-cell renal RNA sequencing data from LN kidneys were examined to deduce the cellular origin of each biomarker.

RESULTS

Screening of 1000 proteins revealed 64 proteins to be significantly elevated in SLE urine, of which 17 were ELISA validated in independent cohorts. Urine Angptl4 (area under the curve (AUC)=0.96), L-selectin (AUC=0.86), TPP1 (AUC=0.84), transforming growth factor-β1 (TGFβ1) (AUC=0.78), thrombospondin-1 (AUC=0.73), FOLR2 (AUC=0.72), platelet-derived growth factor receptor-β (AUC=0.67) and PRX2 (AUC=0.65) distinguished AR from ANR SLE, outperforming anti-dsDNA, C3 and C4, in terms of specificity, sensitivity and positive predictive value. In multivariate regression analysis, urine Angptl4, L-selectin, TPP1 and TGFβ1 were highly associated with disease activity, even after correction for demographic variables. In SLE patients with serial follow-up, urine L-selectin (followed by urine Angptl4 and TGFβ1) were best at tracking concurrent or pending disease flares. Importantly, several proteins elevated in LN urine were also expressed within the kidneys in LN, either within resident renal cells or infiltrating immune cells, based on single-cell RNA sequencing analysis.

CONCLUSION

Unbiased planar array screening of 1000 proteins has led to the discovery of urine Angptl4, L-selectin and TGFβ1 as potential biomarker candidates for tracking disease activity in LN.

Value of biomarkers for predicting immunoglobulin A vasculitis nephritis outcome in an adult prospective cohort

Background

Henoch-Schönlein purpura, more recently renamed immunoglobulin A vasculitis (IgAV), is a systemic vasculitis characterized by IgA deposits. The current markers used to assess IgAV inaccurately evaluate the risk of nephritis occurrence and its long-term outcomes. The current study assessed biomarkers of nephritis outcomes.

Methods

This French multicentre prospective study enrolled 85 adult patients at the time of disease onset. Patients were assessed for clinical and biological parameters and re-examined after 1 year. Immunoglobulins, cytokines, IgA glycosylation, IgA complexes and neutrophil gelatinase-associated lipocalin (NGAL) concentrations were assessed in blood and urine.

Results

We identified 60 patients with IgAV-related nephritis (IgAV-N) and 25 patients without nephritis (IgAV-woN). At the time of inclusion (Day 1), the serum levels of galactose-deficient IgA1 (Gd-IgA1) and urinary concentrations of IgA, IgG, IgM, NGAL, interleukin (IL)-1β, IL-6, IL-8, IL-10, IgA-IgG and IgA-sCD89 complexes were higher in the IgAV-N patients than in the IgAV-woN patients (P < 0.005 for all comparisons). After follow-up (1 year), 22 patients showed a poor outcome. Among the tested markers, urine IgA at disease onset adequately reclassified the risk of poor outcome over conventional clinical factors, including estimated glomerular filtration rate, proteinuria and age (continuous net reclassification improvement = 0.72, P = 0.001; integrated discrimination improvement = 0.13, P = 0.009) in IgAV patients.

Conclusions

Taken together, these results showed that serum Gd-IgA1 and urinary IgA, IgG, IgM, NGAL, IL-1β, IL-6, IL-8, IL-10, IgA-IgG and IgA-sCD89 complexes were associated with nephritis in IgAV patients. Urinary IgA level may improve patient risk stratification for poor outcome.

Association between the interferon regulatory factor 5 rs2004640 functional polymorphism and systemic lupus erythematosus: an updated meta-analysis

OBJECTIVE

The aim of this study is to determine whether the functional interferon regulatory factor 5 ( IRF5) polymorphism rs2004640 is associated with susceptibility to systemic lupus erythematosus (SLE) in multiple ethnic populations.

METHODS

A meta-analysis was conducted on the T allele of the IRF5 rs2004640 polymorphism in all study participants as well as each ethnic population.

RESULTS

Twenty research articles that included 28 comparative studies of 20,892 patients and 24,930 controls were included in the meta-analysis. The Asian population had a much lower prevalence of the T allele than any other study population at 28%, and the European population had the highest prevalence of the T allele at 52%. Meta-analysis showed an association between the IRF5 rs2004640 polymorphism and SLE in all participants (odds ratio = 1.472, 95% confidence interval = 1.370-1.582, p < 0.001). Analysis after stratification by ethnicity indicated that the IRF5 rs2004640 T allele is significantly associated with SLE in Europeans, Asians, Latin Americans and Arabs.

CONCLUSIONS

This meta-analysis confirms that the IRF5 rs2004640 polymorphism is associated with SLE susceptibility in different ethnic groups, and that its prevalence is ethnicity dependent.

[Correlation between TGF-B gene promoter-509C/T polymorphism and IgA nephropathy in core families in Guangxi Zhuang Autonomous Region and the therapeutic effect of dendrobium]

OBJECTIVE

To investigate the correlation between transformation growth factor (TGF- B) polymorphisms and IgA nephropathy and the therapeutic effect of dendrobium on IgA nephropathy.

METHODS

Polymerase chain reaction- restriction fragment length polymorphism (PCR- RFLP) and direct sequencing were used for analysis of 118 patients with IgA nephropathy from core families in Guangxi Zhuang Autonomous Region. The imbalanced transfer of TGF iso1-509 C/T in the affected offsprings was observed by transfer imbalance test and HRR analysis. The TGF-B genotype of the patients and the core family members were detected. The therapeutic effects of Dendrobium candidum combined with hormone and ACEI/ARB treatments were evaluated by observing the patient's urine protein (24 hUpr), serum albumin (ALB), creatinine (Scr) and urea nitrogen (BUN) levels.

RESULTS

In the 118 patients with IgA nephropathy, we identified TGF-B 1 promoter -509C/T genotype CC in 32 (27.1%) cases, CT in 58 (49.2%) cases, and TT in 28 (23.7%) cases. In the core family of the patients, CC genotype was found in 33 (28.0%) cases, CT in 55 (46.6%) cases, and TT in 30 (28.0%) cases. The treatments significantly lowered 24 hUpr, Scr, and BUN levels (P > 0.05) in patients with CC genotype, significantly lowered 24 hUpr and BUN levels in patients with CT genotype (P < 0.05), and significantly lowered 24 hUpr and BUN level and increased (P < 0.05) ALB level (P < 0.01) in patients with TT genotype.

CONCLUSIONS

There is no significant correlation between TGF-B promoter - 509C/T polymorphism and IgA nephropathy. The patients with CC genotype are sensitive to the treatments with hormone and ACEI/ ARB and show a stronger response to combined treatments with dendrobium.

Interferon regulatory factor 5 gene polymorphism in Egyptian children with systemic lupus erythematosus

Background

Increased expression of interferon-inducible genes is implicated in the pathogenesis of systemic lupus erythematosus (SLE). Interferon regulatory factor 5 (IRF5) is one of the transcription factors regulating interferon and was proved to be implicated in the pathogenesis of SLE in different populations.

Objectives

The objective of this study was to investigate the correlation between polymorphisms of the IRF5 gene and SLE susceptibility in a cohort of Egyptian children and to investigate their association with clinico-pathological features, especially lupus nephritis.

Subjects and methods

Typing of interferon regulatory factor 5 rs10954213, rs2004640 and rs2280714 polymorphisms were done using polymerase chain reaction-restriction fragment length polymorphism for 100 children with SLE and 100 matched healthy controls.

Results

Children with SLE had more frequent T allele and TT genotype of rs2004640 ( Pc = 0.003 and 0.024, respectively) compared to controls. Patients with nephritis had more frequent T allele of rs2004640 compared to controls ( Pc = 0.003). However the allele and genotype frequencies of the three studied polymorphisms did not show any difference in patients with nephritis in comparison to those without nephritis. Haplotype GTA of rs10954213, rs2004640 and rs2280714, respectively, was more frequent in lupus patients in comparison to controls ( p = 0.01) while the haplotype GGG was more frequent in controls than lupus patients ( p = 0.011).

Conclusion

The rs2004640 T allele and TT genotype and GTA haplotype of rs rs10954213, rs2004640, and rs2280714, respectively, can be considered as risk factors for the development of SLE. The presence of the rs2004640 T allele increases the risk of nephritis development in Egyptian children with SLE.

The Relationships between Polymorphisms in Genes Encoding the Growth Factors TGF-β1, PDGFB, EGF, bFGF and VEGF-A and the Restenosis Process in Patients with Stable Coronary Artery Disease Treated with Bare Metal Stent

Background

Neointima forming after stent implantation consists of vascular smooth muscle cells (VSMCs) in 90%. Growth factors TGF-β1, PDGFB, EGF, bFGF and VEGF-A play an important role in VSMC proliferation and migration to the tunica intima after arterial wall injury. The aim of this paper was an analysis of functional polymorphisms in genes encoding TGF-β1, PDGFB, EGF, bFGF and VEGF-A in relation to in-stent restenosis (ISR).

Materials and Methods

265 patients with a stable coronary artery disease (SCAD) hospitalized in our center in the years 2007–2011 were included in the study. All patients underwent stent implantation at admission to the hospital and had another coronary angiography performed due to recurrence of the ailments or a positive result of the test assessing the coronary flow reserve. Angiographically significant ISR was defined as stenosis >50% in the stented coronary artery segment. The patients were divided into two groups–with angiographically significant ISR (n = 53) and without significant ISR (n = 212). Additionally, the assessment of late lumen loss (LLL) in vessel was performed. EGF rs4444903 polymorphism was genotyped using the PCR-RFLP method whilst rs1800470 (TGFB1), rs2285094 (PDGFB) rs308395 (bFGF) and rs699947 (VEGF-A) were determined using the TaqMan method.

Results

Angiographically significant ISR was significantly less frequently observed in the group of patients with the A/A genotype of rs1800470 polymorphism (TGFB1) versus patients with A/G and G/G genotypes. In the multivariable analysis, LLL was significantly lower in patients with the A/A genotype of rs1800470 (TGFB1) versus those with the A/G and G/G genotypes and higher in patients with the A/A genotype of the VEGF-A polymorphism versus the A/C and C/C genotypes. The C/C genotype of rs2285094 (PDGFB) was associated with greater LLL compared to C/T heterozygotes and T/T homozygotes.

Conclusions

The polymorphisms rs1800470, rs2285094 and rs6999447 of the TGFB1, PDGFB and VEGF-A genes, respectively, are associated with LLL in patients with SCAD treated by PCI with a metal stent implantation.

Targeted IgA Fc receptor I (FcαRI) therapy in the early intervention and treatment of pristane-induced lupus nephritis in mice

The Fc receptor I for IgA (FcαRI) down-regulates humoral immune responses and modulates the risk of autoimmunity. This study aimed to investigate whether FcαRI targeting can affect progression of pristine-induced lupus nephritis. In the first experiment (early intervention), four groups of animals were evaluated: untreated FcαRI/FcRγ transgenic (Tg) mice and Tg mice administered control antibody (Ctr Fab), saline and anti-FcαRI Fab [macrophage inflammatory protein (MIP)-8a], respectively, three times a week for 29 weeks, after being injected once intraperitoneally with 0·5 ml pristane. In the second experiment, antibody injection started after the onset of nephritis and was carried out for 2 months, with similar groups as described above. MIP-8a improved proteinuria, decreased the amounts of glomerular injury markers, serum interleukin (IL)-6, IL-1 and monocyte chemoattractant protein (MCP)-1, and F4/80 macrophages in the interstitium and glomeruli, in both experiments. When MIP-8a was used as early intervention, a decrease in mouse serum anti-nuclear antibody (ANA) titres and reduced deposition of immunoglobulins in glomeruli were observed. This effect was associated with reduced serum titres of immunoglobulin (Ig)G2a but not IgG1, IgG2b and IgG3. Furthermore, pathological analysis showed lower glomerular activity index and less fibronectin in MIP-8a treated mice. This study suggests that FcαRI targeting could halt disease progression and lupus activation by selective inhibition of cytokine production, leucocyte recruitment and renal inflammation. Our findings provide a basis for the use of FcαRI as a molecular target for the treatment of lupus.

Insight into gene polymorphisms involved in toll-like receptor/interferon signalling pathways for systemic lupus erythematosus in South East Asia

Polymorphisms in genes involved in toll-like receptor/interferon signalling pathways have been reported previously to be associated with SLE in many populations. This study aimed to investigate the role of seven single nucleotide polymorphisms within TNFAIP3, STAT4, and IRF5, which are involved in upstream and downstream pathways of type I interferon production, in SLE in the South East Asian populations. Genotyping of 360 Malaysian SLE patients and 430 normal healthy individuals revealed that minor alleles of STAT4 rs7574865 and rs10168266 were associated with elevated risk of SLE in the Chinese and Malay patients, respectively (P = 0.028, odds ratio (OR) = 1.42; P = 0.035, OR = 1.80, respectively). Polymorphisms in TNFAIP3 and IRF5 did not show significant associations with SLE in any of the ethnicities. Combined analysis of the Malays, Chinese, and Indians for each SNP indicated that STAT4 rs10168266 was significantly associated with the Malaysian SLE as a whole (P = 0.014; OR = 1.435). The meta-analysis of STAT4 rs10168266, which combined the data of other studies and this study, further confirmed its importance as the risk factor for SLE by having pooled OR of 1.559 and P value of <0.001.

Periodontal disease bacteria specific to tonsil in IgA nephropathy patients predicts the remission by the treatment

Background

Immunoglobulin (Ig)A nephropathy (IgAN) is the most common form of primary glomerulonephritis in the world. Some bacteria were reported to be the candidate of the antigen or the pathogenesis of IgAN, but systematic analysis of bacterial flora in tonsil with IgAN has not been reported. Moreover, these bacteria specific to IgAN might be candidate for the indicator which can predict the remission of IgAN treated by the combination of tonsillectomy and steroid pulse.

Methods and Findings

We made a comprehensive analysis of tonsil flora in 68 IgAN patients and 28 control patients using Denaturing gradient gel electrophoresis methods. We also analyzed the relationship between several bacteria specific to the IgAN and the prognosis of the IgAN. Treponema sp. were identified in 24% IgAN patients, while in 7% control patients (P = 0.062). Haemophilus segnis were detected in 53% IgAN patients, while in 25% control patients (P = 0.012). Campylobacter rectus were identified in 49% IgAN patients, while in 14% control patients (P = 0.002). Multiple Cox proportional-hazards model revealed that Treponema sp. or Campylobactor rectus are significant for the remission of proteinuria (Hazard ratio 2.35, p = 0.019). There was significant difference in remission rates between IgAN patients with Treponema sp. and those without the bacterium (p = 0.046), and in remission rates between IgAN patients with Campylobacter rectus and those without the bacterium (p = 0.037) by Kaplan-Meier analysis. Those bacteria are well known to be related with the periodontal disease. Periodontal bacteria has known to cause immune reaction and many diseases, and also might cause IgA nephropathy.

Conclusion

This insight into IgAN might be useful for diagnosis of the IgAN patients and the decision of treatment of IgAN.

Genetic evidence for involvement of adaptive immunity in the development of IgA nephropathy: MHC class II alleles are protective in a Caucasian population

There is evidence suggesting that IgA nephropathy (IgAN) is an immunological disease. The role of HLA class II DR beta 1 (DRB1) has previously not been well studied. The aim of our study was to investigate the association of HLA-DRB1 variants with IgAN in a Swedish Caucasian cohort. Our study consisted of 213 patients with biopsy proven IgAN, all of self-reported Caucasian ancestry. As a control cohort, 1569 healthy subjects from the same population in Sweden were included. HLA-DRB1 low-resolution genotyping was performed and odds ratios were calculated to assess the risk. In an allelic model the HLA-DRB1(*)03 and (*)10, demonstrated association for IgAN after correction for multiple comparison, with subsequent OR=0.54 (95% CI 0.37-0.78) and 3.44 (95% CI 1.67-7.07). When the influence of risk allelic groups was adjusted for protective allelic groups and vice versa, only a protective effect of HLA-DRB1(*)03 remained significant. In conclusion, the variants of HLA-DRB1 were associated with IgAN of which the HLA-DRB1(*)03 revealed a strong protective effect for IgAN. Our data replicates finding from other Caucasian populations and suggest that involvement of adaptive immunity may be of importance in the development of the disease.

TRAF1 gene polymorphism correlates with the titre of Gp210 antibody in patients with primary biliary cirrhosis

Background. Polymorphisms of TRAF1 (Tumor necrosis factor receptor-associated factor 1) are associated with rheumatoid arthritis (RA). Whether TRAF1 polymorphisms confer increased risk for primary biliary cirrhosis (PBC), an autoimmune liver disease which can co-exist with RA, is unknown. Aim of the Study. To assess the frequency of the RA-conferring susceptibility TRAF1 polymorphisms rs3761847 and rs2900180 in a cohort of PBC patients. The association of TRAF1 polymorphisms with clinical features and autoantibody markers was also analyzed. Methods. We studied 179 PBC patients and 300 controls. Samples were genotyped for TRAF1 gene polymorphisms by real-time PCR. Autoantibodies were tested by ELISA. Results. The frequency of rs3761847 and rs2900180 polymorphisms did not differ between patients and controls. Laboratory or clinical features were not associated with specific polymorphisms. Gp210 autoantibody titres were conspicuously higher among GG homozygotes of rs3761847 as compared with AA homozygotes (P = 0.02). In contrast, antichromatin titers were higher in AA compared to GG rs3761847 homozygotes (P = 0.04). Rheumatoid factor IgG titres were significantly higher in rs2900180 TT homozygotes than CC homozygotes (P = 0.02). Conclusions. TRAF1 polymorphisms occur with the similar frequency in PBC patients and in the general population, but their presence is probably involved in the regulation of specific PBC-related autoantibodies.

Lupus nephritis: a critical review

Lupus nephritis remains one of the most severe manifestations of systemic lupus erythematosus associated with considerable morbidity and mortality. A better understanding of the pathogenesis of lupus nephritis is an important step in identifying more targeted and less toxic therapeutic approaches. Substantial research has helped define the pathogenetic mechanisms of renal manifestations and, in particular, the complex role of type I interferons is increasingly recognized; new insights have been gained into the contribution of immune complexes containing endogenous RNA and DNA in triggering the production of type I interferons by dendritic cells via activation of endosomal toll-like receptors. At the same time, there have been considerable advances in the treatment of lupus nephritis. Corticosteroids have long been the cornerstone of therapy, and the addition of cyclophosphamide has contributed to renal function preservation in patients with severe proliferative glomerulonephritis, though at the cost of serious adverse events. More recently, in an effort to minimize drug toxicity and achieve equal effectiveness, other immunosuppressive agents, including mycophenolate mofetil, have been introduced. Herein, we provide a detailed review of the trials that established the equivalency of these agents in the induction and/or maintenance therapy of lupus nephritis, culminating in the recent publication of new treatment guidelines by the American College of Rheumatology. Although newer biologics have been approved and continue to be a focus of research, they have, for the most part, been relatively disappointing compared to the effectiveness of biologics in other autoimmune diseases. Early diagnosis and treatment are essential for renal preservation.

Associations between TNFSF4 and TRAF1-C5 gene polymorphisms and systemic lupus erythematosus: a meta-analysis

OBJECTIVE

The aim of this study was to determine whether tumor necrosis factor superfamily 4 (TNFSF4) and TNF receptor-associated factor 1-complement 5 (TRAF1-C5) polymorphisms confer susceptibility to systemic lupus erythematosus (SLE).

METHODS

The authors conducted meta-analyses on associations between polymorphisms of the TNFSF4 (rs2205960, rs1234315, rs10489265) and TRAF1-C5 (rs10818488, rs3761847) genes and SLE susceptibility, using fixed and random effects models.

RESULTS

A total of 21 comparative studies were included in this meta-analysis; meta-analysis showed an association between the minor allele of rs2205960 of TNFSF4 and SLE in all study subjects (odds ratio [OR]=1.356, 95% confidence interval [CI]=1.275-1.442, p<1.0×10(-9)). Meta-analysis revealed an association between the minor alleles of rs1234315 and rs10489265 of TNFSF4 and SLE in Asians (OR=1.366, 95% CI=1.295-1.440, p<1.0×10(-9); OR=1.463, 95% CI=1.208-1.771, p=9.7×10(-5)). The minor allele of rs10818488 of TRAF1-C5 was found to be significantly associated with SLE in Europeans (OR=1.210, 95% CI=1.115-1.313, p=5.0×10(-6)). The association p-values remained significant after multiple corrections.

CONCLUSIONS

This meta-analysis confirms that TNFSF4 polymorphisms are associated with susceptibility to SLE in Asians and Europeans. An association was found between the rs10818488 polymorphism of TRAF1-C5 and susceptibility to SLE in Europeans.

Basic and translational concepts of immune-mediated glomerular diseases

Genetically modified immune responses to infections and self-antigens initiate most forms of GN by generating pathogen- and danger-associated molecular patterns that stimulate Toll-like receptors and complement. These innate immune responses activate circulating monocytes and resident glomerular cells to release inflammatory mediators and initiate adaptive, antigen-specific immune responses that collectively damage glomerular structures. CD4 T cells are needed for B cell-driven antibody production that leads to immune complex formation in glomeruli, complement activation, and injury induced by both circulating inflammatory and resident glomerular effector cells. Th17 cells can also induce glomerular injury directly. In this review, information derived from studies in vitro, well characterized experimental models, and humans summarize and update likely pathogenic mechanisms involved in human diseases presenting as nephritis (postinfectious GN, IgA nephropathy, antiglomerular basement membrane and antineutrophil cytoplasmic antibody-mediated crescentic GN, lupus nephritis, type I membranoproliferative GN), and nephrotic syndrome (minimal change/FSGS, membranous nephropathy, and C3 glomerulopathies). Advances in understanding the immunopathogenesis of each of these entities offer many opportunities for future therapeutic interventions.

Activation of type I interferon pathway in systemic lupus erythematosus: association with distinct clinical phenotypes

Growing evidence over the last few years suggests a central role of type I IFN pathway in the pathogenesis of systemic autoimmune disorders. Data from clinical and genetic studies in patients with systemic lupus erythematosus (SLE) and lupus-prone mouse models, indicates that the type I interferon system may play a pivotal role in the pathogenesis of several lupus and associated clinical features, such as nephritis, neuropsychiatric and cutaneous lupus, premature atherosclerosis as well as lupus-specific autoantibodies particularly against ribonucleoproteins. In the current paper, our aim is to summarize the latest findings supporting the association of type I IFN pathway with specific clinical manifestations in the setting of SLE providing insights on the potential use of type I IFN as a therapeutic target.