Association of the MCP-1 −2518 A/G Polymorphism and No Association of Its Receptor CCR2 −64 V/I Polymorphism with Lupus Nephritis

Association of Immune-Related Genetic and Epigenetic Alterations with Lupus Nephritis

BACKGROUND

The familial clustering phenomenon together with environmental influences indicates the presence of a genetic and epigenetic predisposition to systematic lupus erythematosus (SLE). Interestingly, regarding lupus nephritis (LN), the worst complication of SLE, mortality, and morbidity were not consistent with SLE in relation to sexuality and ethnicity.

SUMMARY

Genetic and epigenetic alterations in LN include genes and noncoding RNAs that are involved in antigen-presenting, complements, immune cell infiltration, interferon pathways, and so on. Once genetic or epigenetic change occurs alone or simultaneously, they will promote the formation of immune complexes with autoantibodies that target various autoantigens, which results in inflammatory cytokines and autoreactive immune cells colonizing renal tissues and contributing to LN.

KEY MESSAGES

Making additional checks for immunopathology-related heredity and epigenetic factors may lead to a more holistic perspective of LN.

Update on Lupus Nephritis: Looking for a New Vision

Lupus nephritis (LN) is one of the most common manifestations of systemic lupus erythematosus (SLE), affecting approximately 40% of patients with lupus. It represents a major risk factor for morbidity and mortality, and 10% of patients with LN will develop end-stage kidney disease (ESKD). Therefore, there are a number of areas for improvement in the field of LN such as the search for new clinical biomarkers with a more accurate correlation with lupus activity and the redefinition of the histological classification into different subgroups in order to guide a personalized treatment. Although the role of protocol repeat kidney biopsies in LN is controversial, recent publications suggest that repeat histological assessment can be useful in guiding therapeutic decisions that may yield toward precision medicine. In the last decade, LN therapy has remained largely unchanged, with a probability of achieving complete or partial remission not exceeding 60-70%. Thus, optimization of old treatment strategies and search for new agents are urgently needed in order to improve outcomes such as mortality or development of ESKD. Future trials should focus in addressing unanswered issues such as the appropriate dose and duration of immunosuppressive treatment, timing of steroid withdrawal, and drug toxicity. In addition, data are still lacking regarding pregnancy and kidney transplantation in LN and knowledge about these important areas is essential for the management of a subset of patients with SLE. In summary, several major gaps are still present in the therapeutic approach and follow-up of patients with LN. The development of new clinical trial designs will be crucial in the search to improve long-term outcomes.

An update on genetic susceptibility in lupus nephritis

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by multiple system involvement and positive serum autoantibodies. Lupus nephritis (LN) is the most common and serious complication of SLE, and it is the main cause of death in patients with SLE. Abnormalities in the immune system lead to LN and involve a variety of cells (T cells, B cells, macrophages, NK cells, etc.), cytokines (interleukin, tumor necrosis factor α, etc.) and their related pathways. Previous studies have shown that the interactions of genetic, epigenetic and environmental factors contribute to the pathogenesis and development of LN. In recent years, one genome-wide association study (GWAS) and a number of gene association studies have explored the susceptibility genes of LN, including immunization-, inflammation-, adhesion- and other pathway-related genes. These genes participate in or suggest the pathogenesis and progression of LN. In this review, we summarize the genetic susceptibility of LN and discuss the possible mechanism underlying the susceptibility genes of LN.

An update on genetic susceptibility in lupus nephritis

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by multiple system involvement and positive serum autoantibodies. Lupus nephritis (LN) is the most common and serious complication of SLE, and it is the main cause of death in patients with SLE. Abnormalities in the immune system lead to LN and involve a variety of cells (T cells, B cells, macrophages, NK cells, etc.), cytokines (interleukin, tumor necrosis factor α, etc.) and their related pathways. Previous studies have shown that the interactions of genetic, epigenetic and environmental factors contribute to the pathogenesis and development of LN. In recent years, one genome-wide association study (GWAS) and a number of gene association studies have explored the susceptibility genes of LN, including immunization-, inflammation-, adhesion- and other pathway-related genes. These genes participate in or suggest the pathogenesis and progression of LN. In this review, we summarize the genetic susceptibility of LN and discuss the possible mechanism underlying the susceptibility genes of LN.

Monocyte chemoattractant protein-1 (MCP-1)-2518 A/G polymorphism and lupus nephritis risk: A PRISMA-compliant meta-analysis

BACKGROUND

Monocyte chemoattractant protein-1 (MCP-1) plays an important role in the development of allergic inflammatory reactions by recruiting various immune cells, which is associated with many autoimmune diseases, but the association with the MCP-1-2518A/G gene polymorphism and lupus nephritis (LN) was still controversial in previous studies. Thus, we performed a meta-analysis to derive a more precise evaluation of the association between MCP-1 -2518A/G polymorphism and LN risk and evaluated influence of ethnicity and source of controls.

METHODS

A systematic review and meta-analysis that will be performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Relevant literatures dated to September 2016 were acquired from the PubMed, EMBASE, Cochran Library databases. A total of 961 LN cases and 1867 controls were extracted from 10 published case-control studies. We used odds ratios (OR) with 95% confidence intervals (CI) to assess the risk of LN with MCP-1-2518A/G.

RESULTS

Our meta-analysis suggested that MCP-1-2518A/G polymorphism was associated with the risk of LN (GG vs AG+AA: P < .01, OR = 1.42, 95% CI: 1.13-1.79 and A vs G P = .02, OR = 0.74, 95% CI: 0.58-0.95). Then the subgroup analysis showed MCP-1 -2518 A/G gene has a certain correlation with LN susceptibility in the American population (GG vs AA: P < .01, OR = 5.70, 95% CI: 2.09-15.50, GG vs AG+AA: P < .01, OR = 3.31, 95% CI: 1.97-5.54, GG+AG vs AA: P < .01, OR = 2.86, 95% CI: 1.14-7.18, and A vs G: P < .01, OR = 0.43, 95% CI: 0.24-0.79), while no significant risk in Europeans and Asians.

CONCLUSION

The current meta-analysis suggests that the MCP-1-2518A/G polymorphism is associated with an increased risk of LN, especially in the American population. However, better-designed studies with larger sample sizes are needed to validate the results.

A functional SNP MCP-1 (-2518A/G) predispose to renal disorder in Indian Systemic Lupus Erythematosus patients

Systemic Lupus Erythematosus (SLE) is a clinically heterogeneous chronic, inflammatory autoimmune disorder that affects multiple organs where exact etiology of the disease is not yet clearly understood. Various evidences suggest that genetic polymorphisms in inflammatory mediators like cytokines and chemokines may influence development of the disease. Here, we investigated whether functional polymorphism at the Monocyte Chemoattractant Protein-1 (MCP-1) regulatory region associates with disease phenotype in Indian SLE patients. This case control study included 200 SLE patients and 201 ethnically matched healthy controls. Genotyping of MCP-1 (-2518 A/G) polymorphism was performed using PCR-RFLP method. Serum MCP-1 levels were detected by bead-based multiplex immunoassay. Serum MCP-1 levels were found to be higher in patients compared with healthy individuals (p<0.0001). A significant difference for MCP-1G allele frequency (OR=1.9, 95%CI=1.4-2.6, p<0.0001) was observed among SLE patients against healthy individuals. A significant difference in the distribution of MCP-1 -2518GG (OR=3.0, 95%CI=1.4-6.7, p=0.0041) and AG+GG genotypes (OR=2.0, 95%CI=1.4-3.0, p=0.0005) was also noted among SLE patients when compared with healthy individuals. A significant association was observed between A/G and G/G versus A/A genotypes with renal manifestations (p<0.0001, Pc<0.001). Serum MCP-1 levels in active LN patients were found to be significantly higher than inactive LN (p=0.0059), mild LN (p=0.0061) as well as non-LN patients (p=0.0001). These findings suggest that -2518G allele of MCP-1 -2518 A/G polymorphism is associated with renal disorders and may influence MCP-1 gene expression among Indian SLE patients.

Organ-specific biomarkers in lupus

Systemic lupus erythematosus (SLE) is a complex and highly heterogeneous disease, which affects multiple organs, including joints, skin, kidneys, heart, hematopoietic system, and nerve system. While the etiopathogenesis of SLE still remains unclear, genetic susceptibilities and aberrant epigenetic modifications are believed to be involved. For precision therapy, it is necessary to assess accurately and objectively organ involvements and disease activity, which is difficult by current clinical laboratory tests. Biomarkers, which are a biologic, genetic, epigenetic or a chemical characteristic and conveniently detectable, serve as measures of disease diagnosis, activity, prognosis, and manifestation prediction, thereby providing instruction for individualized therapy. In addition, biomarkers differ according to different manifestations, since the disease activity index and treatments vary significantly. For example, unlike other non-renal SLE, lupus nephritis requires significant immunosuppressive drugs. Over the past decades, the research on biomarkers in lupus has been strengthened and numerous promising biomarkers have been identified at levels of genomics, transcriptomics and proteomics. In this review, we summarize the conventional and novel biomarkers in the tissue-specific manner, and discuss their roles in specific organ diagnosis, future manifestation prediction, disease activity assessment and their correlation with histology results. By doing so, it aims to shed a light on individualized treatment.

MCP1 2518 A/G polymorphism affects progression of childhood focal segmental glomerulosclerosis

Monocyte chemoattractant protein-1 (MCP-1) is a highly specific chemokine for monocytes and plays roles in pathogenesis of various renal diseases. The aim of this study is to investigate the effect of MCP1 2518 A/G polymorphism on the incidence and clinical course of focal segmental glomerulosclerosis (FSGS) in children. MCP1 2518 A/G genotype was identified by PCR-RFLP in 60 biopsy-proven FSGS patients, 76 steroid sensitive nephrotic syndrome (SSNS) patients, and 96 healthy children. MCP-1 levels in urine and serum were measured by ELISA in all patients and the correlations of genotype with MCP-1 levels and clinical outcome were evaluated. The genotype frequencies for MCP1 were similar in all groups. The percentage of patients who develop chronic renal failure was higher in patients with AA allele compared to GA or GG alleles (46% vs. 35% respectively, p < 0.01, Odds ratio: 1.59). Serum MCP-1 levels were similar in all groups, whereas urinary MCP-1 levels of the patients with FSGS (1680 pg/mg creatinine) were significantly higher than that of patients with SSNS (365 pg/mg creatinine, p < 0.05) and healthy controls (348 pg/mg creatinine; p < 0.05). Urinary MCP-1 levels were correlated with the degree of proteinuria in FSGS group (r = 0.529, p = 0.016). Our results suggest that the AA genotype might be a risk factor for the progression of renal disease in FSGS and MCP1 genotyping may help the physicians to predict prognosis in these patients.

The protective effect of MCP-1 -2518 A>G promoter polymorphism in Turkish chronic renal failure patients requiring long-term hemodialysis

OBJECTIVE

Monocyte chemoattractant protein-1 (MCP-1) plays a major role in the pathogenesis and progression of different types of human renal disease. Therefore, in this study, we aimed to investigate the effect of MCP-1 gene -2518 A>G promoter polymorphism in chronic renal failure (CRF) patients requiring long-term hemodialysis.

METHODS

The study population consisted of 201 adult CRF patients requiring long-term hemodialysis and 194 healthy controls. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used for genotyping of MCP-1 -2518 A>G polymorphism in the CRF patients and healthy controls.

RESULTS

There were statistically significant differences in terms of genotypic (χ (2) = 12.69, p = 0.02) and allelic (χ (2) = 5.72, p = 0.02) frequencies of MCP-1 -2518 A>G between CRF patients and control subjects. According to our results, in the patient group MCP-1 -2518 AA genotype frequency was significantly higher than that of control group. On the other hand, heterozygous AG genotype frequency in the control group was significantly higher than that of the study group. Three different main disease subgroups of CRF (hypertension, diabetes mellitus, and atherosclerosis) patients were also evaluated, and significant associations were found between hypertension (genotype: χ (2) = 9.28, p = 0.01; allele: χ (2) = 6.00, p = 0.01), atherosclerosis (genotype: χ (2) = 5.37, p = 0.02; allele: χ (2) = 4.13, p = 0.04), and distributions of MCP-1 -2518 A>G genotypes and alleles. However, no significant association was found between diabetes mellitus and distributions of MCP-1 -2518 A>G genotype and allele frequencies (genotype: χ (2) = 2.37, p = 0.3; allele: χ (2) = 1.88, p = 0.17).

CONCLUSION

Current data show that MCP-1 -2518 AA genotype may cause susceptibility to CRF, while G allele may have a protective effect against development of CRF. In addition, MCP-1 -2518 AA genotype seems to associate with CRF originated from hypertension and atherosclerosis in our study population.

A MCP-1 promoter polymorphism at G-2518A is associated with spontaneous preterm birth

Monocyte chemoattractant protein-1 (MCP-1) is an important chemokine involved in the pathogenesis of spontaneous preterm birth (SPTB). We examined whether the MCP-1 G-2518A polymorphism is associated with the risk of SPTB in a Chinese population. The MCP-1 G-2518A polymorphism was genotyped in 569 preterm singleton neonates and in 673 term neonates using polymerase chain reaction-restriction fragment length polymorphism analysis. The distribution of the MCP-1 G-2518A genotype and the allele frequencies between the SPTB patients and the controls were not significantly different in the overall sample. However, we found that the AA genotype was associated with significantly increased susceptibility to very SPTB (<32 weeks) [odds ratio (OR) 2.07; 95 % confidence interval (CI), 1.27-3.36; P = 0.005) and extremely SPTB (<28 weeks) (OR 2.74; 95 % CI, 1.10-6.72; P = 0.014) compared with -2518G-positive genotypes (GG + GA genotypes). When extremely preterm neonates and very preterm neonates were combined, the AA genotype was also significantly associated with increased susceptibility to SPTB (OR 2.23; 95 % CI, 1.40-3.54; P < 0.001). The MCP-1 G-2518A polymorphism was not associated with increased susceptibility to SPTB in patients with premature rupture of the membranes (PROM) or in those without PROM. Our findings suggest that the MCP-1 G-2518A polymorphism may plays a role in mediating the susceptibility to SPTB in the Chinese population. Knowledge of genetic factors contributing to the pathogenesis of SPTB may have implications for screening and treatment of this disorder.

Selective elevation of circulating CCL2/MCP1 levels in patients with longstanding post-vaccinal macrophagic myofasciitis and ASIA

Several medical conditions sharing similar signs and symptoms may be related to immune adjuvants. These conditions described as ASIA (Autoimmune/inflammatory Syndrome Induced by Adjuvants), include a condition characterized by macrophagic myofasciitis (MMF) assessing long-term persistence of vaccine derived-alum adjuvants into macrophages at sites of previous immunization. Despite increasing data describing clinical manifestations of ASIA have been reported, biological markers are particularly lacking for their characterization and follow up. We report an extensive cytokine screening performed in serum from 44 MMF patients compared both to sex and age matched healthy controls and to patients with various types of inflammatory neuromuscular diseases. Thirty cytokines were quantified using combination of Luminex® technology and ELISA. There was significant mean increase of serum levels of the monocytechemoattractant protein 1 (CCL2/MCP-1) in MMF patients compared to healthy subjects. MMF patients showed no elevation of other cytokines. This contrasted with inflammatory patients in whom CCL2/MCP-1 serum levels were unchanged, whereas several other inflammatory cytokines were elevated (IL1β, IL5 and CCL3/MIP1α). These results suggest that CCL2 may represent a biological marker relevant to the pathophysiology of MMF rather than a non specific inflammatory marker and that it should be checked in the other syndromes constitutive of ASIA.

Association of STAT4 polymorphism with severe renal insufficiency in lupus nephritis

Lupus nephritis is a cause of significant morbidity in systemic lupus erythematosus (SLE) and its genetic background has not been completely clarified. The aim of this investigation was to analyze single nucleotide polymorphisms (SNPs) for association with lupus nephritis, its severe form proliferative nephritis and renal outcome, in two Swedish cohorts. Cohort I (n = 567 SLE cases, n = 512 controls) was previously genotyped for 5676 SNPs and cohort II (n = 145 SLE cases, n = 619 controls) was genotyped for SNPs in STAT4, IRF5, TNIP1 and BLK. Case-control and case-only association analyses for patients with lupus nephritis, proliferative nephritis and severe renal insufficiency were performed. In the case-control analysis of cohort I, four highly linked SNPs in STAT4 were associated with lupus nephritis with genome wide significance with p = 3.7 × 10(-9), OR 2.20 for the best SNP rs11889341. Strong signals of association between IRF5 and an HLA-DR3 SNP marker were also detected in the lupus nephritis case versus healthy control analysis (p <0.0001). An additional six genes showed an association with lupus nephritis with p <0.001 (PMS2, TNIP1, CARD11, ITGAM, BLK and IRAK1). In the case-only meta-analysis of the two cohorts, the STAT4 SNP rs7582694 was associated with severe renal insufficiency with p = 1.6 × 10(-3) and OR 2.22. We conclude that genetic variations in STAT4 predispose to lupus nephritis and a worse outcome with severe renal insufficiency.

Biomarker profiling for lupus nephritis

Lupus nephritis (LN) is one of the most severe manifestations of systemic lupus erythematosus (SLE), which is associated with significant morbidity and mortality of SLE patients. The pathogenesis of LN involves multiple factors, including genetic predisposition, epigenetic regulation and environmental interaction. Over the last decade, omics-based techniques have been extensively utilized for biomarker screening and a wide variety of variations which are associated with SLE and LN have been identified at the levels of genomics, transcriptomics and proteomics. These studies and discoveries have expanded our understanding of the molecular basis of the disease and are important for identification of potential therapeutic targets for disease prediction and early treatment. In this review, we summarize some of the recent studies targeted at the identification of LN-associated biomarkers using genomics and proteomic approaches.

CC chemokine receptors and chronic inflammation--therapeutic opportunities and pharmacological challenges

Chemokines are a family of low molecular weight proteins with an essential role in leukocyte trafficking during both homeostasis and inflammation. The CC class of chemokines consists of at least 28 members (CCL1-28) that signal through 10 known chemokine receptors (CCR1-10). CC chemokine receptors are expressed predominantly by T cells and monocyte-macrophages, cell types associated predominantly with chronic inflammation occurring over weeks or years. Chronic inflammatory diseases including rheumatoid arthritis, atherosclerosis, and metabolic syndrome are characterized by continued leukocyte infiltration into the inflammatory site, driven in large part by excessive chemokine production. Over years or decades, persistent inflammation may lead to loss of tissue architecture and function, causing severe disability or, in the case of atherosclerosis, fatal outcomes such as myocardial infarction or stroke. Despite the existence of several clinical strategies for targeting chronic inflammation, these diseases remain significant causes of morbidity and mortality globally, with a concomitant economic impact. Thus, the development of novel therapeutic agents for the treatment of chronic inflammatory disease continues to be a priority. In this review we introduce CC chemokine receptors as critical mediators of chronic inflammatory responses and explore their potential role as pharmacological targets. We discuss functions of individual CC chemokine receptors based on in vitro pharmacological data as well as transgenic animal studies. Focusing on three key forms of chronic inflammation--rheumatoid arthritis, atherosclerosis, and metabolic syndrome--we describe the pathologic function of CC chemokine receptors and their possible relevance as therapeutic targets.

The rs1024611 regulatory region polymorphism is associated with CCL2 allelic expression imbalance

CC chemokine ligand 2 (CCL2) is the most potent monocyte chemoattractant and inter-individual differences in its expression level have been associated with genetic variants mapping to the cis-regulatory regions of the gene. An A to G polymorphism in the CCL2 enhancer region at position -2578 (rs1024611; A>G), was found in most studies to be associated with higher serum CCL2 levels and increased susceptibility to a variety of diseases such as HIV-1 associated neurological disorders, tuberculosis, and atherosclerosis. However, the precise mechanism by which rs1024611influences CCL2 expression is not known. To address this knowledge gap, we tested the hypothesis that rs1024611G polymorphism is associated with allelic expression imbalance (AEI) of CCL2. We used haplotype analysis and identified a transcribed SNP in the 3'UTR (rs13900; C>T) can serve as a proxy for the rs1024611 and demonstrated that the rs1024611G allele displayed a perfect linkage disequilibrium with rs13900T allele. Allele-specific transcript quantification in lipopolysaccharide treated PBMCs obtained from heterozygous donors showed that rs13900T allele were expressed at higher levels when compared to rs13900C allele in all the donors examined suggesting that CCL2 is subjected to AEI and that that the allele containing rs1024611G is preferentially transcribed. We also found that AEI of CCL2 is a stable trait and could be detected in newly synthesized RNA. In contrast to these in vivo findings, in vitro assays with haplotype-specific reporter constructs indicated that the haplotype bearing rs1024611G had a lower or similar transcriptional activity when compared to the haplotype containing rs1024611A. This discordance between the in vivo and in vitro expression studies suggests that the CCL2 regulatory region polymorphisms may be functioning in a complex and context-dependent manner. In summary, our studies provide strong functional evidence and a rational explanation for the phenotypic effects of the CCL2 rs1024611G allele.

No association of monocyte chemoattractant protein-1 -2518 A/G polymorphism with the risk of primary glomerulonephritis in the Polish population

Various studies have indicated that chemokines such as monocyte chemotactic protein-1 (MCP-1) play an important role in the pathogenesis of primary glomerulonephritis (GN) and other glomerular diseases. Moreover, patients with primary GN display aberrant galactosylation of the O-linked carbohydrate moieties of IgA. Therefore, we analysed the distribution of the functional MCP-1 -2518 A > G (rs 1024611) and 1 beta 1,3-galactosyltransferase (C1GalT1) 1365 A > G (rs1047763) polymorphic variants in patients with primary GN (n = 144) and controls (n = 437) in a sample of the Polish population. We did not find a significant difference in the prevalence of the MCP-1 -2518 A > G and C1GalT1 1365 A > G polymorphisms in patients with primary GN and healthy individuals. Odds Ratio (OR) for GN patients with the MCP-1 -2518 GG genotype was 0.869 (95% CI = 0.410-1.840, P = 0.7130), and OR of the -2518 GG and -2518AG genotypes was 1.004 (95% CI = 0.689-1.464, P = 0.9836). OR for C1GalT1 1365AA genotype was 0.484 (95% CI = 0.181-1.293, P = 0.1402) and OR of the 1365AA and 1365AG genotypes was 0.839 (95% CI = 0.573-1.228, P = 0.3651). We also did not observe a difference in the distribution of alleles between patients and controls. The MCP-1 -2518 G allelic OR was 0.976 (95% CI = 0.725-1.314, P = 0.8744). The OR for the C1GalT1 1365A allele was 0.816 (95% CI = 0.596-1.118, P = 0.205). Moreover, there was no significant association between the MCP-1 -2518 A > G and C1GalT1 1365 A > G genotypes with different morphological types of primary GN or clinical manifestations. Our observations indicate that the MCP-1 -2518 A > G and C1GalT1 1365 A > G polymorphisms might not be a risk factor in the incidence of primary GN in the Polish population.

ZC3H12A (MCPIP1): molecular characteristics and clinical implications

BACKGROUND

ZC3H12A is a gene whose absence is related to autoimmune disorders and to other phenotypical alterations.

METHODS

A comprehensive review of the structure, molecular functions and regulation of ZC3H12A gene and its protein MCPIP1 is done in order to understand their clinical implications.

RESULTS

ZC3H12A, at 1p34.3, has 9860bp, six exons and 61 described SNPs. Eleven are non-synonymous thus leading to changes in MCPIP1, the protein encoded by ZC3H12A. MCPIP1 is induced by MCP-1 and IL-1 whose signals are transduced through the NF-kβ and MAPkinase pathways. This protein acts as an RNAse by degrading chemokine transcripts such as IL-1 as well as its own mRNA and as a transcription factor by reducing the expression of other chemokines induced by NF-kβ such as MCP-1. It also up-regulates genes involved in several differentiation processes and apoptosis. Therefore, ZC3H12A is an equilibrium gatekeeper that not only regulates its own inducers but also controls the regulation by degrading its own mRNA.

CONCLUSION

Understanding ZC3H12A gives a comprehensive panorama that promises to improve our understanding of processes in which this gene is involved including autoimmune, infectious and cardiovascular diseases.