Influence of cytokine gene polymorphisms on focal segmental glomerulosclerosis

Angiotensin-Converting Enzyme Gene Polymorphism in Children with Idiopathic Nephrotic Syndrome, Effect on Biopsy Findings

OBJECTIVE

Angiotensin converting enzyme (ACE) converts angiotensin I into angiotensin II. The ACE gene shows an I/D polymorphism, which correlates with ACE concentrations. The aim of this study is to evaluate the distribution of the ACE I/D genotype in children with idiopathic nephrotic syndrome (INS) and healthy controls and study the effect of this polymorphism on clinical and pathologic findings.

METHODS

ACE gene I/D polymorphism of 104 patients with INS and 119 controls were determined.

RESULTS

The DD, ID, and II genotypes were found in 58.7%, 22.1%, and 19.2% of the patients, and in 79.8%, 2.5%, and 17.6% of controls, respectively (p > 0.05). The ID genotype was seen more frequently in patients resistant to treatment.

CONCLUSION

The observed differences with previous reports suggest the influence of the genetic background on disease course. The ACE I/D gene polymorphism's role seems to be more important in renal disease progression than susceptibility.

Potential genetic risk factors in angiotensin-converting enzyme-inhibitor-induced angio-oedema

AIMS

The pathophysiology of angiotensin-converting enzyme inhibitor (ACEi)-induced angio-oedema remains unclear. We have investigated the impact of ACE insertion/deletion (I/D) polymorphism in combination with serum ACE activity as well as the bradykinin B2 receptor 2/3 and c.C181T polymorphisms.

METHODS

We analysed the ACE I/D as well as bradykinin B2 (2/3 and C181T) receptor polymorphisms in 65 patients with documented episodes of ACEi-induced angio-oedema and 65 patients matched for age and sex being under ACEi treatment without history of angio-oedema. Furthermore, we determined serum ACE activity in 47 of the 65 angio-oedema patients 3 months after the angio-oedema attack and compared these values with 51 healthy individuals (control II).

RESULTS

No risk association was identified between ACE I/D (I-allele: 0.42 vs. 0.41, D-allele: 0.58 vs. 0.59; P= 0.095) or bradykinin B2 receptor polymorphisms and the development of angio-oedema during ACEi treatment. We found a trend of lower serum ACE activity in ACE I/I genotypes in comparison with control II (I/I: 28 +/- 4.5 vs. 33 +/- 1.8 U l(-1); ID: 39 +/- 3.3 vs. 41 +/- 1 U l(-1); DD: 56 +/- 6.7 vs. 52 +/- 1.8 U l(-1); P= 0.9).

CONCLUSIONS

Our data suggest that polymorphism of ACE I/D and the bradykinin B2 receptor polymorphisms are not involved in the development of ACEi-induced angio-oedema when considered individually. Further studies should be carried out to clarify whether a combination of these polymorphisms might be a risk factor for ACEi-induced angio-oedema.

Interleukin-6 gene polymorphism and faster progression to end-stage renal failure in chronic glomerulonephritis

Interleukin-6 (IL-6) is a multifunctional cytokine produced by different cell types, including monocytes, lymphocytes, endothelial and mesangial cells. Deregulated production of IL-6 was found to be involved in mesangial proliferative glomerulonephritis. We investigated whether the single nucleotide polymorphism (SNP) in the promoter region of the IL-6 gene is associated with a development of chronic glomerulonephritis (CGN). The study group consisted of 541 patients with CGN. Of those 338 already progressed to ESRD. The control group involved 253 healthy individuals. All subjects were genotyped for the -634 C/G polymorphism of the IL-6 gene by polymerase chain reaction (PCR). PCR product was digested with BsrBI restriction endonuclease and analyzed on 3% agarose. The allele and genotype frequencies were similar between CGN patients in a pre-dialysis stage and control subjects. Significantly increased frequency of the G allele was observed in the ESRD patients (13% vs. 6% in pre-dialysis stage, P < 0.01). After dividing ESRD patients according to time from reported disease onset to ESRD, those with time < or =5 years showed even higher G allele frequency (21% vs. 13% in entire ESRD group). Interestingly, most of the GG homozygotes were in this faster progressing group. Both subgroups were comparable for sex, age, BMI, total cholesterol and serum creatinine. The multivariate logistic regression analysis revealed that the IL-6 genotype with the G allele was an independent risk factor of progression to ESRD (P < 0.001). Our results indicate that the IL-6 -634 G/C polymorphism may be a possible risk factor for faster progression of chronic glomerulonephritis to ESRD. It is also possible that this polymorphism is in linkage disequilibrium with another functional polymorphism in the II-6 gene or its vicinity.

Correlation between a gene polymorphism of tumor necrosis factor-alpha (G/A) and end-stage renal disease: a pilot study from north India

BACKGROUND

Patients with chronic kidney disease manifest an inflammatory state in comparison to healthy individuals. Tumor necrosis factor-alpha (TNF-alpha) is a potent pro-inflammatory cytokine involved in initiation and progression of renal injury. We examined the 2-promoter region polymorphism of TNF-alpha gene G to A at -308 and at +488 sites in end-stage renal disease (ESRD) subjects.

METHODS

The TNF-alpha -308 G/A and +488 G/A polymorphisms were genotyped in 231 patients aged 36.5+/-10, and in 180 matched controls (34.96+/-11.3) by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and amplification refractory mutation system (ARMS-PCR) method, respectively.

RESULTS

The genotypic distribution of TNF-alpha -308 and +488 were significantly different between patients and controls (P<0.001 and P<0.006), respectively. The AA genotype was more frequent in ESRD patients than controls for both the sites (42% vs. 2.8% and 17.3% vs. 2.2%), respectively. The allelic frequency of TNF-alpha A was also higher in cases than in controls for both the sites (P<0.001; OR=2.96; 95% CI=2.228-3.945 and P<0.013; OR=1.422; 95% CI=1.078-1.876). Significant difference was observed for haplotype frequency distribution between ESRD patients and controls and 'A-G#' haplotype showed >9-fold higher risk (OR=9.886, 95% CI=4.408-22.172). The two polymorphisms were in linkage disequilibrium in the control group (D'=0.8047, P<0.001).

CONCLUSION

Both the variants of TNF-alpha (-308 and +488) polymorphism had significant association and may thus be a strong predisposing risk factor for ESRD in a cohort of north Indian population. Further, individuals with haplotypes A-G# may be at higher risk for ESRD.

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.