Polymorphisms of the tumour necrosis factor alpha gene at position -308 and TNFd microsatellite in primary IgA nephropathy

Tumor Necrosis Factor-α G-308A Polymorphism and Sporadic IgA Nephropathy: A Meta-Analysis Using a Genetic Model-Free Approach

Tumor necrosis factor-α (TNF-α) is a potent pro-inflammatory cytokine, involved in the pathogenesis and progression of immunoglobulin A nephropathy (IgAN). A bi-allelic polymorphism in the promoter region, at position -308 (G/A) of the TNF-α gene (rs1800629) is associated with an increased TNF-a production. However, several previous association studies of TNF-α G-308A polymorphism and IgAN rendered contradictory findings. The objective of the present study is to shed light on these inconclusive results and clarify the role of TNF-α and any possible contribution of this factor in the development and progression of sporadic IgAN. Therefore, a meta-analysis of all available genetic association studies relating the TNF-α G-308A polymorphism to the risk for development and/or progression of IgAN was conducted. Seven studies were included in the meta-analysis. Three of them included populations of European descent (Caucasians) and four involved Asians. The generalized odds ratio (OR_G) was used to estimate the risk for the development and/or progression of the disease. Overall, the meta-analysis did not detect any significant association between the G-308A variant and both the risk of developing IgAN and the risk for progression of IgAN. In conclusion, these results suggest that TNF-α does not constitute a key component in the genetic architecture of sporadic IgAN. However, further evidence deciphering the influence of TNF-α on IgAN is still needed.

Onset of IgA nephropathy in a patient treated with infliximab for ankylosing spondylitis

We report the case of a 43-year-old man, suffering from ankylosing spondylitis and treated with Infliximab 5 mg/kg every 2 months, with an excellent disease control. During a follow-up consultation, an incipient renal insufficiency is detected. A urine analysis showed haematuria and proteinuria and a renal puncture-biopsy revealed an image of IgA nephropathy.Several cases of IgA nephropathy have been reported in the literature associated with ankylosing spondylitis. Some of them occur in patients treated with antitumour necrosis factor, but it is unclear whether this pathology is caused by the treatment or whether treatment failed to prevent its occurrence.Our clinical case highlights the importance of regular monitoring of renal function in patients with ankylosing spondylitis, as well as urinary spotting.The question of whether the disease itself, the treatment or other factors such as immune dysregulation could be held responsible for kidney disease will be addressed in the discussion.

Spondyloarthritis-Associated IgA Nephropathy

Introduction

IgA nephropathy (IgAN) can be associated with spondyloarthritis (SpA). The course of SpA-associated IgAN remains largely unknown due to the absence of large cohorts.

Methods

This retrospective study included patients with biopsy-proven IgAN and definite SpA. Kidney biopsies were centrally examined and scored according to the IgAN Oxford Classification. Thirty-two patients fulfilled the inclusion criteria, with a male:female ratio of 9:1 and median age of 27 and 37 years at SpA and IgAN diagnosis, respectively. HLA-B27 was positive in 90% of cases, and most patients (60%) presented with ankylosing spondylitis. The mean baseline estimated glomerular filtration rate (eGFR) was 84 ± 26 ml/min per 1.73 m², and the urine protein-to-creatinine ratio was 0.19 g/mmol.

Results

Renal biopsy revealed frequent presence of crescents (33%) and interstitial inflammation (18%). Despite almost constant use of renin-angiotensin system inhibitors, combined with steroids in 13 of 32 patients, renal outcome was particularly poor. After a median follow-up of 5.9 years, 4 patients (12.5%) reached end-stage renal disease and 41% of patients experienced a >50% decrease of eGFR. The mean annual eGFR decline rate was -4.3 ± 6.7 ml/min per 1.73 m². The risk of reaching class IV or V chronic kidney disease (CKD) stage during follow-up was associated with the presence of hypertension, level of proteinuria, and baseline S- and T-scores of the Oxford.

Conclusion

SpA-associated IgAN is associated with a poor renal outcome, despite frequent use of steroids. Tumor necrosis factor (TNF)-α blockade did not appear to influence the rate of eGFR decline in this setting.

[IgA nephropathy]

IgA nephropathy is the most common form of primary glomerulonephritis worldwide and an important cause of chronic kidney disease and end-stage kidney failure. Its pathophysiology remains in part unsolved but it is recognized as an immune complex disease. Recent years have brought progress in the field through the discovery of several genetic susceptibility loci and the formulation of the multi-hit pathogenesis model. Presentation, clinical course and histology can be extremely variable, making any histological classification still difficult. Indeed, most therapeutic studies until now include patients based only on the severity of clinical criteria but the new classification of Oxford should change that. Only the management of patients with nephropathy with minimal change glomerular lesions and nephrotic syndrome, or extra-capillary glomerulonephritis and rapidly progressive renal failure, is consensual: Corticosteroids alone for the first and associated with immunosuppressive drugs for the latter. The recent Kidney Disease Improving Global Outcomes (KDIGO) consensus treatment guideline is still controversial, especially in light of the last clinical studies. Corticosteroid therapy can be discussed in patients with proteinuria greater than 1 g/day without renal failure. All IgA nephropathy patients should benefit from the global management of chronic glomerular disease, including a renin-angiotensin system blocker in the presence of hypertension or proteinuria.

Heat shock protein 70-2 and tumor necrosis factor-α gene polymorphisms in Chinese children with Henoch-Schönlein purpura

BACKGROUND

Henoch-Schönlein purpura (HSP) or IgA-associated vasculitis is related to immune disturbances. Polymorphisms of the heat shock protein 70-2 gene (HSP70-2) and the tumor necrosis factor-a gene (TNF-α) are known to be associated with immune diseases. The purpose of this study was to investigate the likely association of HSP70-2 (+1267A/G) and TNF-α (+308A/G) gene polymorphisms with HSP in children.

METHODS

The polymerase chain reaction restriction fragment length polymorphism method was used to detect the HSP70-2 and TNF-α polymorphisms in 205 cases of children with HSP and 53 controls; and the association of these polymorphisms with HSP and HSP nephritis (HSPN) was analyzed.

RESULTS

The G/G genotypic frequencies at the +1267A/G position of HSP70-2 in the HSP group (22.9%) were significantly higher than those in the healthy control group (9.4%) (χ(2)=4.764, P<0.05). The frequencies of the A/A, A/G and G/G genotypes of HSP70-2 in patients in the nephritis-free group and the HSPN group showed no statistically significant difference. The A/A genotype frequency at the +308G/A position of TNF-α in the HSP group was 8.3%, which was higher than that in the control group (χ(2)=6.447, P<0.05). The A allele frequency of TNF-α in the HSP group was higher than that in the control group, with a statistically significant difference (χ(2)=7.241, P<0.05).

CONCLUSIONS

The HSP70-2 (+1267A/G) and TNF-α (+308G/A) gene polymorphisms were associated with HSP in children. The G/G homozygosity of HSP70-2 and the A/A homozygosity of TNF-α may be genetic predisposing factors for HSP.

Association of STR polymorphisms in CMA1 and IL-4 with asthma and atopy: the SAPALDIA cohort

Asthma is a chronic pulmonary disorder that is characterized by airway inflammation and bronchial hyperreactivity. Several genetic loci have been associated with asthma, and some of these associations have been replicated in independent studies. However, larger population-based replication studies for the association of short tandem repeat (STR) polymorphisms with asthma are limited. In this study, we investigated the association of STR polymorphisms in genes encoding mast cell chymase (CMA1), uteroglobin (UGB), tumor necrosis factor-α (TNF-α) and interleukin-4 (IL-4) with asthma and atopic phenotypes in the large population-based Swiss Cohort Study SAPALDIA. Our results show that the STR polymorphism in the CMA1 gene is associated with asthma and that this association is even stronger with atopic asthma. Similarly, we observed a weak association of the IL-4 2-allele with asthma that tended to be stronger for atopic asthma than for nonatopic asthma. This minor IL-4 2-allele was also associated with higher IgE levels, with a higher risk for a positive skin prick test and with a trend for a higher risk for bronchial hyperresponsiveness. These results support previous findings suggesting a role for CMA1 and IL-4 in atopic asthma and for IL-4 in atopy in general.

TNF microsatellite alleles may confer protection against the development of lipodystrophy syndrome in Brazilian HIV patients

The aim of this study was to evaluate the frequency of TNFa-e microsatellites and the promoter region (TNF-308 and TNF-238) in HIV/AIDS-infected patients presenting or not lipodystrophy syndrome (LS). The design is the genetic case-control association study. Microsatellite and the TNF promoter region polymorphisms were amplified by PCR and submitted to polyacrylamide gel electrophoresis. The genotypes and allele frequencies for 67 HIV-positive patients with lipodystrophy were compared with 50 HIV-positive patients with no evidence of lipodystrophy and with 131 healthy HIV-negative individuals. The presence of the TNFa5 allele could provide HIV/AIDS patients with protection against developing LS. The presence of TNF-308G allele, as well as of its homozygote TNF-308GG, were associated with susceptibility to developing LS. In addition, the presence of the haplotype TNFe3-d3-238G-308A-c1-a5-b7 suggests protection against developing that syndrome. This study highlights that polymorphic sites spanning the region nearby the TNF locus are associated with LS development in HIV/AIDS patients.

[Glomerulonephritis with IgA mesangial deposits]

IgA nephropathy is the primitive glomerulonephritis the most frequently encountered worldwide. In about one case out of three, it is responsible for the progression from progressive renal failure to end-stage renal failure. The pathophysiological mechanisms of this disease which is mediated by immune complexes remain unclear. The presentation, clinical progression and optical microscope aspect of the renal biopsy may widely vary, making any histological classification very difficult. Most therapeutic studies include the patients only on clinical criteria of severity. The only consensual management is that of patients with a nephropathy and mild glomerular lesions and a nephritic syndrome, or with an extracapillar glomerulonephritis and a rapidly progressive renal failure; corticoids are indicated in former cases while corticoids must be combined with immunosuppressive agents in the latter ones. Corticotherapy may be considered in patients with a proteinuria higher than 1g/day without renal failure. In any patient with primitive IgA nephropathy, the overall management used for chronic glomerulopathy must be initiated, including, in case of arterial hypertension or proteinuria, the renin-angiotensin system blockade.

Tumor necrosis factor region polymorphisms are associated with AIDS and with cytomegalovirus retinitis

BACKGROUND

The tumor necrosis factor (TNF) gene is located within the highly polymorphic major histocompatibility complex region, exhibiting the -308 GA promoter region polymorphism and six microsatellites (TNFa-f) spanning the region nearby the TNF locus.

OBJECTIVE

In the present study, we evaluated the frequency of -308 GA and TNFa-e polymorphisms and respective haplotypes (in chromosomal sequence: TNFd-TNFe-308GA-TNFc-TNFa-TNFb), in 222 patients with AIDS, 52 of whom exhibited cytomegalovirus retinitis, and in 202 healthy HIV-negative individuals.

METHOD

TNF microsatellite and single nucleotide polymorphism typings were performed by PCR followed by polyacrylamide gel electrophoresis.

RESULTS

The TNF-308A allele and the 4-3-G-2-7-1 haplotype were associated with susceptibility to AIDS, whereas the TNFb4 allele and the 3-3-G-1-11-4 haplotype were associated with protection against AIDS development. The TNFc2 allele and the 4-1-G-2-2-1 haplotype, which contains the TNFc2 allele, were associated with cytomegalovirus retinitis.

CONCLUSION

This study highlights that polymorphic sites spanning the region nearby the TNF locus are associated with AIDS per se and with cytomegalovirus retinitis in AIDS patients.

Genetic predictors of renal failure

BACKGROUND

Both environmental and genetic factors contribute to the development and progression of chronic kidney disease. The completion of the human genome sequence and advances in genomic technology make possible identification of gene variants associated with renal failure.

OBJECTIVE

This review discusses the relevant genetic studies in chronic kidney disease, with particular emphasis on the most common causes of end stage renal failure, diabetic nephropathy and glomerulonephritis.

METHODS

Most of the studies presented were performed in recent years and employed association studies, both population-based and with candidate genes, as well as the genome-wide association and genome-wide scan approaches.

RESULTS/CONCLUSION

Increasing evidence supports an important role of genetic susceptibility in the development and progression of renal failure. Identification of disease genes will allow the identification of patients at high risk and the development of new strategies to prevent or delay the renal disease process.

Serological and genetic factors in early recurrence of IgA nephropathy after renal transplantation

BACKGROUND

The relative role of IgA anomalies and genetic factors in IgA nephropathy (IgAN) recurrence after transplantation has never been investigated in a single cohort.

METHODS

Sixty-one transplanted patients who had IgAN as an original disease (30 with biopsy-proved early recurrence, median 2.9 yr post-transplant), and 120 controls, were investigated for aberrantly glycosylated IgA1, IgA binding to mesangial matrix, macromolecular IgA (IgA/fibronectin and uteroglobulin/IgA/fibronectin complexes), and polymorphisms of cytokines [tumor necrosis factor alpha (TNFalpha), interleukin 10 (IL-10), IL-6, interferon gamma and transforming growth factor beta 1] and renin-angiotensin system (angiotensinogen converting enzyme, angiotensin II receptor 1, and angiotensinogen) genes.

RESULTS

At multivariate logistic regression analysis, recurrence showed a border-line association with aberrantly glycosylated IgA1 [odds ratio (OR) 8.172, p = 0.077], and was significantly less frequent in carriers of -308 AG/AA TNF-alpha"high producer" genotype (OR 0.125, p = 0.036) and -1082, -819, -592 ACC/ATA IL-10 "low producer" (OR 0.038, p = 0.009) genotypes.

CONCLUSION

High levels of aberrantly glycosylated IgA1 do not appear to play a strong crucial role in recurrence of IgAN. Polymorphisms of TNFalpha and IL-10 known to condition Th1 prevalence were associated with protection from early recurrence of IgAN.

The genetics of IgA nephropathy

IgA nephropathy is the most common form of primary glomerulonephritis. Variations in clinical manifestations indicate that a diagnosis of IgA nephropathy encompasses multiple disease subsets that cannot be distinguished on the basis of renal pathology or clinical variables alone. Familial forms of the disease have been reported throughout the world, but are probably under-recognized because associated urinary abnormalities are often intermittent in affected family members. IgA nephropathy has complex determination, with different genes probably causing disease in different patient subgroups. Of the many pathogenic mechanisms reported, defects in IgA1 glycosylation that lead to formation of immune complexes have been consistently implicated. Here, we present the evidence for genetic contributions to the disease, review clinical patterns of familial disease, and summarize some of the most promising genetic studies conducted to date. Linkage-based approaches to the study of familial forms of the disease have identified significant or suggestive loci on chromosomes 6q22-23, 2q36, 4q26-31, 17q12-22 and 3p24-23, but no causal gene has yet been identified. Many interesting, but poorly replicated, genetic association studies have also been reported. We discuss recent developments in analytic tools that should enable genetic studies of sporadic forms of disease by the genome-wide association approach.

TNFA2 and d2 alleles of the tumor necrosis factor alpha gene polymorphism are associated with onset/occurrence of idiopathic membranous nephropathy

Idiopathic membranous nephropathy (IMN) has a strong association with the major histocompatibility complex HLA B8DR3(17)DQ2 haplotype. The tumor necrosis factor (TNF)A gene is located within the major histocompatibility complex region on chromosome 6. We have studied the influence of two functional polymorphisms; the -308 (promoter region) and the TNFd microsatellites on initiation and/or progression of IMN. This was a case-control study comparing data from 100 Caucasians patients (67 male subjects; 67%) with IMN to 232 Caucasians local controls (171 male subjects; 74%). We have analyzed genotypes and alleles distributions and the role of these polymorphisms in disease progression towards end-stage renal failure or patient death. For -308 TNFA polymorphism, distribution of genotypes was significantly different between IMN and controls (chi(2)=16.25; P=0.0003): the A2 allele frequency was 28.0% in IMN vs 15.3% in controls (chi(2)=14.57; P=0.0001). For TNFd polymorphism, alleles distribution (from d1 to d7) was also significantly different between IMN and controls (chi(2)=56.74; P<0.0001) with both diminished d3 allele frequency (chi(2)=27.30; P<0.0001; Pc=0.001) and increased d2 allele frequency (chi(2)=29.95; P<0.0001; Pc=0.001) in IMN. We could not isolate any significant and independent influence of these different genotypes on IMN disease progression. The TNFA2 and TNFd2 alleles were strongly associated with occurrence/initiation of IMN and should be considered as susceptibility genes for this disease.

CC-chemokine receptor five gene polymorphism in primary IgA nephropathy: the 32 bp deletion allele is associated with late progression to end-stage renal failure with dialysis

The chemokine (CK) receptor 5 (CCR5) is necessary for two adjacent cysteines (CC)-CKs such as Regulated upon Activation Normal T cell Expressed and Secreted, a/o Macrophage Inflammatory Protein 1alpha/beta to mediate their inflammatory properties. The CCR5 gene polymorphism with 32-basepair deletion (d32) leads to receptor inactivation/dysfunction in homo/heterozygous individuals. We have evaluated its role in both initiation and/or progression of primary immunoglobulin A (IgA) nephropathy (IGAN) in a case-control study involving a prospective cohort of 318 IGAN patients and a matched group of 294 controls. Genotyping was performed by a two-specific primers single polymerase chain reaction technique: normal allele (nl) vs d32 allele. The d32 allele frequency was not different in patients (11.0%) vs controls (8.3%), indicating no significant influence on IGAN initiation. Genotype to clinical phenotype correlation demonstrated that progression to renal/patient death was associated with the d32 allele: 18.2% (12 out of 66 with d32) vs 8.3% (21 out of 252); chi(2)=6.73; P=0.017. The Kaplan-Meier survival without renal/patient death was worse in d32-positive patients (log-rank test; P=0.002). The Cox regression analyses confirmed that the nl/nl genotype was a significant and independent protective factor for progression to end-stage renal failure (ESRF)/dialysis: beta/standard error (s.e.)=-3.1; chi(2)=9.5; relative risk=0.31 (95% confidence interval 0.15-0.65); P=0.002. The d32-CCR5 polymorphism played a significant role in the progression of primary IGAN, with the nl/nl genotype being an independent protective factor for late progression towards ESRF/dialysis. These data raise question about the usefulness of systematic CCR5 genotyping in IGAN patients.

Tumor necrosis factor-alpha gene G-308A polymorphism is a risk factor for the development of membranous glomerulonephritis

BACKGROUND

Tumor necrosis factor-alpha (TNF-alpha) is a major pro-inflammatory cytokine. Recently, the G-308A polymorphism of the TNF-alpha gene has been associated with modified gene expression and increased TNF-alpha production in the -308A allele. We evaluated its influence on the incidence and clinical course of membranous glomerulonephritis.

METHODS

We studied 53 patients with biopsy-proven primary membranous glomerulonephritis followed up for 5.7 +/- 4.9 years. 100 volunteers were analyzed as controls. According to the slope of the curve of reciprocal serum creatinine against time, group A (slow progressors, n = 35) and group B (fast progressors, n = 18) were defined. TNF-alpha G-308A polymorphism was determined by polymerase chain reaction amplification.

RESULTS

The frequency of the A-allele (associated with higher TNF-alpha levels) was significantly higher in patients than control subjects (patients: G-allele: 0.66, A-allele: 0.34; controls: G-allele 0.85, A-allele 0.15, p < 0.001). Similarly, the genotype distribution differed significantly between our study and control populations (patients: GG-genotype: 41.5%, GA: 49.1%, AA 9.4%; controls: GG: 71%, GA: 27%, AA 2%, p = 0.001). Age, renal function, proteinuria and blood pressure were similar at the time of renal biopsy between patients with different genotypes (NS). There was also a tendency towards an overpresentation of the A-allele in group B indicating a possible impact on the progression of membranous nephropathy, but a significance was not reached. Furthermore, no impact on renal survival in the Kaplan- Meier analysis was detected (NS).

CONCLUSION

Our results suggest that TNF-alpha gene G-308A polymorphism is a risk factor for the development of membranous glomerulonephritis.

Genetic studies of IgA nephropathy

IgA nephropathy is the commonest form of glomerulonephritis worldwide, but we still know relatively little about its pathogenesis. Potentially, genetic studies might provide new insights and suggest novel therapeutic approaches to this important cause of chronic kidney disease. Two approaches that are likely to yield new information are analysis of multiply affected pedigrees and large-scale, well-controlled association studies.

Musculin/MyoR is expressed in kidney side population cells and can regulate their function

Musculin/MyoR is a new member of basic helix-loop-helix transcription factors, and its expression is limited to skeletal muscle precursors. Here, we report that musculin/MyoR is expressed in adult kidney side population (SP) cells and can regulate their function. SP phenotype can be used to purify stem cell–rich fractions. Microarray analysis clarified that musculin/MyoR was exclusively expressed in kidney SP cells, and the cells resided in the renal interstitial space. Musculin/MyoR-positive cells were decreased in acute renal failure, but infusion of kidney SP cells increased musculin/MyoR-positive cells and improved renal function. Kidney SP cells in reversible acute renal failure expressed a high level of renoprotective factors and leukemia inhibitory factor (LIF), but not in irreversible chronic renal failure. In cultured kidney SP cells, LIF stimulated gene expression of renoprotective factors, and down-regulation of musculin/MyoR augmented LIF-induced gene expression. Our results suggest that musculin/MyoR may play important roles not only in developmental processes but also in regenerative processes in adult tissue.

IgA nephropathy: an update

PURPOSE OF REVIEW

The elution of nephrectomy specimens from patients with IgA nephropathy yields IgA1 with galactose-deficient glycans in the hinge region. In this review, we summarize recent advances in our understanding of the role of the aberrant immunoglobulin in the pathogenesis of this form of glomerulonephritis. In the absence of a disease-specific therapy, we discuss current therapeutic approaches.

RECENT FINDINGS

Galactose-deficient IgA1 forms macromolecular complexes that bind to mesangial cells and stimulate them to proliferate, synthesize various cytokines and chemokines, and secrete extracellular matrix proteins. Whereas progress has been made in understanding the glycosylation pathways of IgA1 O-linked glycans and binding galactose-deficient IgA1-complexes to mesangial cells, there is still no IgA nephropathy-specific therapy. The current approach to suppress the effects of angiotensin II, by angiotensin-converting enzyme inhibitors, angiotensin II receptor type 1 blockers, or both, as a cornerstone of the therapy of IgA nephropathy has been strengthened by recent studies. Treatment with glucocorticoids, cyclophosphamide, or both, may be appropriate for a subset of IgA nephropathy patients.

SUMMARY

A better understanding of the mechanisms underlying the synthesis of galactose-deficient IgA1, the formation of circulating immune complexes, and interactions with mesangial cells will provide further insights into the pathogenetic mechanisms that culminate in the glomerular and interstitial damage of IgA nephropathy, and could identify novel therapeutic targets in the prevention and management of this renal disease.

Influence of cytokine gene polymorphisms on focal segmental glomerulosclerosis

BACKGROUND

Recently, polymorphisms of cytokine genes have been associated with modified gene expression and increased cytokine production. We evaluated the influence of TGF-beta(1) gene Arg(25)-->Pro, TNF alpha gene G-308A and IL-6 gene G-174C polymorphisms on the clinical manifestations of focal segmental glomerulosclerosis (FSGS).

METHODS

The clinical course of 71 patients with biopsy-proven primary FSGS followed up for 6.0 +/- 4.4 years was studied. Patients were classified according to the slope of reciprocal serum creatinine into slow (n = 49) and fast (n = 22) progressors. One hundred healthy volunteers were analysed as controls. Genetic polymorphisms were determined by PCR amplification.

RESULTS

The genotype distribution of the studied polymorphisms was similar in patients and controls (n.s.). Age, initial renal function, proteinuria and blood pressure did not differ significantly between patients with different genotypes (n.s.). The investigated polymorphisms were not associated with the progression of FSGS as shown by the similar genotype frequencies among slow and fast progressors (n.s.) and the renal survival in the Kaplan-Meier analysis (n.s.).

CONCLUSION

Our results indicate that TGF-beta(1) gene Arg(25)-->Pro, TNF alpha gene G-308A and IL-6 gene G-174C polymorphisms are not risk factors or markers of progression in focal segmental glomerulosclerosis.