Angiotensin-converting enzyme insertion/deletion polymorphism and prognosis of IgA nephropathy

The Influence of ACE Insertion/Deletion Gene Polymorphism on the Risk of IgA Nephropathy: A Debatable Topic

Background

The connection between angiotensin-converting enzyme insertion/deletion (ACE I/D) gene polymorphisms and IgA nephropathy (IgAN) was conflicting. This pooled analysis was performed to explore this issue.

Methods

All eligible investigations were identified from various electronic databases, and the pooled analysis was evaluated using Stata software.

Results

27 studies with 2538 IgAN cases and 3592 controls were included. In overall subjects, ACE D allele, DD, and II genotype were associated with IgAN susceptibility (D vs. I: OR = 1.21, 95% CI: 1.10–1.32, P < 0.001; DD vs. ID + II: OR = 1.38, 95% CI: 1.20–1.60, P < 0.001; and II vs. DD + ID: OR = 0.83, 95% CI: 0.73–0.95, P=0.007). In Asian and Chinese patients, ACE I/D gene polymorphism was also correlated with IgAN vulnerability. Moreover, ACE D allele, DD, and II genotype were correlated with the progression of IgAN (D vs. I: OR = 1.37, 95% CI: 1.09–1.73, P=0.008; DD vs. ID + II: OR = 1.57, 95% CI: 1.06–2.31, P=0.024; and II vs. DD + ID: OR = 0.69, 95% CI: 0.49–0.99, P=0.045). Conversely, in Caucasian subjects, there was no link between ACE I/D gene polymorphism and the risk of IgAN.

Conclusion

ACE I/D gene polymorphism was correlated with the vulnerability and progression of IgAN in Asian and Chinese patients, and ACE D allele and DD homozygote genotype could be adverse factors for IgAN, while the II homozygote genotype could be an advantage factor. But, no significant association was found between ACE I/D gene polymorphism and IgAN in Caucasians.

Serum oxylipin profiles in IgA nephropathy patients reflect kidney functional alterations

Immunoglobulin A nephropathy (IgAN) is a leading cause of chronic kidney disease, frequently associated with hypertension and renal inflammation. ω-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in fish oil (FO) improve kidney function in animal models, but have inconsistent metabolic effects in humans. Oxylipin profiles in serum from IgAN patients supplemented with either FO or corn oil (CO) placebo were analyzed by liquid chromatography coupled to tandem mass spectrometry. EPA cyclooxygenase and lipoxygenase metabolites, and EPA and DHA epoxides and diols were increased in response to FO supplementation, as were total epoxides and epoxide/diol ratios. Several of these metabolites were drivers of separation as assessed by multivariate analysis of FO patients pre- vs. post-supplementation, including 17,18-dihydroxyeicosatrienoic acid, prostaglandin D₃, prostagalandin E₃, Resolvin E1, 12-hydroxyeicosapentaenoic acid, and 10(11)-epoxydocosapentaenoic acid. In patients whose proteinuria improved, plasma total oxylipins as well as several hydroxyoctadecadienoic acids, hydroxyeicosatetraenoic acids, and leukotriene B₄ metabolites were among the metabolites that were significantly lower than in patients whose proteinuria either did not improve or worsened. These data support the involvement of oxylipins in the inflammatory component of IgAN as well as the potential use of oxylipin profiles as biomarkers and for assessing responsiveness to ω-3 fatty acid supplementation in IgAN patients.

Long-term renal survival and related risk factors in patients with IgA nephropathy: results from a cohort of 1155 cases in a Chinese adult population

BACKGROUND

We sought to identify the long-term renal survival rate and related risk factors of progression to renal failure in Chinese adult patients with IgA nephropathy (IgAN) and to quantify the effects of proteinuria during the follow-up on outcome in patients with IgAN.

METHODS

Patients with biopsy-proven primary IgAN in the Nanjing Glomerulonephritis Registry were studied. Renal survival and the relationships between clinical parameters and renal outcomes were assessed.

RESULTS

One thousand one hundred and fifty-five patients were enrolled in this study. The 10-, 15- and 20-year cumulative renal survival rates, calculated by Kaplan-Meier method, were 83, 74 and 64%, respectively. At the time of biopsy, proteinuria>1.0 g/day [hazard ratio (HR) 3.2, P<0.001], estimated glomerular filtration rate (eGFR)<60 mL/min/1.73 m2 (HR 2.6, P<0.001), hypertension (HR 1.9, P<0.001), hypoproteinemia (HR 2.0, P<0.001) and hyperuricemia (HR 2.1, P<0.001) were the independent risk factors. Multivariate Cox analysis showed the time-average proteinuria (TA-P) during follow-up was the most important risk factor of renal failure. Patients with TA-P>1.0 g/day were associated with a 9.4-fold risk than patients with TA-P<1.0 g/day (P<0.001) and 46.5-fold risk than those with TA-P<0.5 g/day (P<0.001). Moreover, patients who achieved TA-P<0.5 g/day benefit much more than those with TA-P between 0.5 and 1.0 g/day (HR 13.1, P<0.001).

CONCLUSIONS

Thirty-six percent of Chinese adult patients with IgAN progress to end stage renal disease within 20 years. Five clinical features-higher proteinuria, hypertension, impaired renal function, hypoproteinemia and hyperuricemia-are independent predictors of an unfavorable renal outcome. The basic goal of anti-proteinuric therapy for Chinese patients is to lower proteinuria<1.0 g/day and the optimal goal is to lower proteinuria to <0.5 g/day.

Association of angiotensin-converting enzyme gene I/D polymorphism with steroid responsiveness in childhood nephrotic syndrome

The aim of the study was to study the distribution of angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism, and its association with steroid responsiveness in children with idiopathic nephrotic syndrome (INS). One hundred twenty-five children with INS were classified into two groups: steroid-sensitive nephrotic syndrome (SSNS: n = 90) and steroid-resistant nephrotic syndrome (SRNS: n=35). The control group consisted of 150 unrelated healthy children. Genomic DNA was extracted from peripheral leucocytes by the standard salting-out method. ACE genotyping was performed and ACE genotypes DD, ID, and II were compared between different groups. The frequency distribution of the DD genotype was significantly increased in children with INS compared to control subjects (P = 0.0012) while the difference was not significant (P = 0.071) between SSNS and control subjects. The frequency distribution of the DD genotype was significantly high in the SRNS group compared to control subjects (P < 0.0001). The distribution of the DD genotype was high in SRNS compared to SSNS group patients (P = 0.016). In conclusion, the presence of the DD genotype may predict risk for steroid resistance in childhood INS.

In vivo activity of epoxide hydrolase according to sequence variation affects the progression of human IgA nephropathy

Epoxyeicosatrienoic acid (EET) regulates the functional integrity of the endothelium. It is hypothesized that the activity of epoxide hydrolase (EPHX2), which determines EET concentration through hydrolysis, may affect the progression of glomerulonephritis. Here, we evaluated the relationship between genetic variations, the in vivo activity of EPHX2, and progression of IgA nephropathy (IgAN). Three single-nucleotide polymorphisms (SNPs) [rs41507953 (K55R), rs751141 (R287Q), and rs1042032] were traced in 401 IgAN patients and 402 normal healthy controls. The in vivo activity of EPHX2 was assessed by measuring substrates/metabolites of the enzyme. None of the polymorphism frequencies differed significantly between patients and controls. However, patients carrying the variant allele (A) of rs751141 possessed better kidney survival than those with the wild-type allele (G; P < 0.001). This association remained significant after adjustment for several risk factors (hazard ratio 1.83, 95% confidence interval 1.13-2.96, P = 0.014). Vascular damage was more prominent in kidney biopsies from patients carrying the G allele of rs751141. The in vivo activity of EPHX2, assessed by the epoxyoctadecenoic acid/dihydroxyoctadecenoic acid ratio using liquid chromatography/mass spectrometry analysis, was elevated in patients with the G allele. The expression of EPHX2 in the human kidney was independent of the sequence variation of the rs751141 allele. Variant rs41507953 was not present in this cohort, and rs1042032 was not associated with progression. Thus the specific measures which regulate EPHX2 activity should be designed for potential therapeutics.

Association between ACE polymorphism and risk of IgA nephropathy: a meta-analysis

BACKGROUND

and objective: The effect of angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism on risk or progression of immunoglobulin A nephropathy (IgAN) is still debated.Therefore, a meta-analysis was performed to evaluate the association of ACE gene polymorphism with IgAN in different ethnic groups.

METHOD

A predefined search strategy was performed to collect data from electronic databases.

RESULTS

Twenty articles were identified for the analysis of the relationship between ACE polymorphism and IgAN risk, including 11 in Asians and nine in Caucasians. There was a markedly positive association between the D allele or DD genotype and IgAN risk in Asians (OR = 1.27, p = 0.006; OR = 1.83, p < 0.0001). However, a link between D allele or DD genotype and IgAN risk was not found in Caucasians (OR = 1.04, p = 0.46; OR = 1.13, p = 0.12). Ten investigations were included for analysis of the association of ACE polymorphism with IgAN progression, including six in Asians and four in Caucasians. These data did not support a link between the ACE D allele or DD genotype and IgAN progression in Asians and Caucasians (Asians: D: OR = 1.03, p = 0.80; DD: OR = 1.43, p = 0.16; Caucasians: D: OR = 1.29, p = 0.22; DD: OR = 1.31, p = 0.17).

CONCLUSIONS

The D allele or DD genotype is associated with IgAN risk in Asian, but not in Caucasian populations; there was no significant association between the D allele or DD gene and IgAN progression for Asians and Caucasians.

ACE Gene Polymorphism in Turkish Children with Nephrotic Syndrome

Since 1990, the role of angiotensin converting enzyme (ACE) gene polymorphism in various renal and cardiac diseases is still debated. This study comprised 71 pediatric patients with nephrotic syndrome, 47 males (66%) and 24 females (34%) with a mean age of 57.4 +/- 37.6 months, and a control group of 83 healthy males (59%) and 57 healthy females (41%) with a mean age of 505 +/- 160.5 months. The distribution of the ACE genotype in the control group was II, 11%; ID, 53%; and DD, 36%, and the nephrotic syndrome was II, 4%; ID, 78%; and DD, 18%. Angiotensin-converting enzyme genotypes were significantly different between patients and control groups (p<0.05). The study groups consisted of 52 (73%) with steroid-sensitive nephrotic syndrome (SNSS) and 19 (27%) with steroid-resistant nephrotic syndrome (SRNS). The distribution of the ACE genotype was II, 6%; ID, 75%; and DD, 19% in the SSNS population and ID, 84% and DD, 16% in the SRNS population. No statistically significant difference was found between steroid sensitivity and ACE genotypes (p=0.5). The results show that ACE I/D polymorphism does not contribute to the steroid resistance, even though this study indicates that the presence of the I/D genotype has a much higher risk--approximately 2.8 times--of having nephrotic syndrome. Further studies with a larger number of patients are needed.

Severity of tubulointerstitial inflammation and prognosis in immunoglobulin A nephropathy

Many risk factors for progression in immunoglobulin A nephropathy (IgAN) have been found. We focused on renal leukocyte infiltrations and cytokines in IgAN. The subjects were 204 IgAN patients. Renal histopathological changes were semiquantitatively graded. Expression of tubulointerstitial Leukocyte common antigen (LCA), CD3, CD68, interleukin (IL)-1beta, and IL-10 was evaluated by immunohistochemistry. These parameters were correlated with progression of IgAN. The significance of these correlations was tested by a multivariate analysis. Glomerulosclerosis, tubular atrophy, interstitial inflammation, and hyaline arteriolosclerosis correlated with progression in all patients and also in patients with initially normal serum creatinine. Tubulointerstitial LCA, CD3, CD68, and IL-1beta expression correlated with progression. CD3 had the strongest correlation. In the multivariate analysis, tubulointerstitial CD3, hypertriglyceridemia, elevated serum creatinine concentration, and interstitial fibrosis were independently associated with progressive disease in all patients, and tubulointerstitial CD3 expression and hyaline arteriolosclerosis in patients with initially normal serum creatinine. We found parameters reflecting tubulointerstitial inflammation to predict deterioration of renal function in IgAN. This was also seen in patients whose serum creatinine was normal at the time of renal biopsy. Our findings show that, an immunohistochemical evaluation of tubulointerstitial inflammation seems to be a useful tool in determining the prognosis in IgAN.

Association of angiotensin I-converting enzyme gene insertion/deletion polymorphism and IgA nephropathy: a meta-analysis

BACKGROUND/AIMS

The angiotensin I-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism has been extensively examined for the association with immunoglobulin A (IgA) nephropathy (IgAN), however, conflicting results have occurred. We performed a meta-analysis to evaluate the association of ACE I/D polymorphism with IgAN in different ethnic groups.

METHODS

11 studies testing the association between ACE I/D polymorphism and IgAN susceptibility, and 9 studies testing the association of ACE I/D with IgAN progression were used in this analysis. The overall odds ratio (OR) was estimated by a fixed or random effect model.

RESULTS

The overall OR for the risk of susceptibility and progression of IgAN in Asians for the DD genotype is 2.37 (95% CI 1.04-5.41) and 1.75 (95% CI 1.24-2.56). The overall OR for the D allele in Asians also showed a similar magnitude, though without statistical significance (p = 0.09, p = 0.13, respectively). In Caucasians, both the DD genotype and D allele were associated with IgAN progression (OR 1.90, 1.61, respectively), but not IgAN susceptibility (p = 0.30, p = 0.41, respectively).

CONCLUSION

Our findings support the notion that ACE I/D polymorphism is associated with IgAN. Meanwhile, the role of ACE I/D polymorphism in Asians is different from that of Caucasians.

Is ACE gene polymorphism a risk factor for renal scarring with low-grade reflux?

The possible relationship between the angiotensin-converting enzyme (ACE) gene insertion/deletion ( I/D) polymorphism and renal scarring secondary to vesicoureteral reflux (VUR) has recently attracted attention and the DD genotype was postulated to be a risk factor for renal scarring. However, available data represent conflicting results. The aim of this study was to investigate the ACE gene I/D polymorphism and the other known risk factors for renal scarring in children with low- and high-grade VUR. The study included 96 (67 females, 29 males) patients (mean age at diagnosis 3.7+/-3.3 years) with VUR that were assessed for ACE I/D gene polymorphism. ACE genotypes were determined as II, ID, and DD using the polymerase chain reaction. The control group consisted of 103 healthy children with the same ethnicity to find the distribution of ACE gene I/D polymorphism in the population. The frequency of renal scarring was 80.8% in the high-grade reflux group and 34.3% in the low-grade reflux group. There was no difference between groups with renal scarring and without scarring with respect to gender, family history of VUR, age at diagnosis of VUR, associated urological abnormalities, frequency of urinary tract infection episodes, and the occurrence of bilateral or unilateral VUR. Genotype DD was found to be a significant risk factor for renal scarring in the study group by multivariate regression analysis (odds ratio 3.79, P=0.011). It was not a risk factor in high-grade reflux patients (odds ratio 0.60, P=0.62). However, it was a risk factor in low-grade patients with respect to renal scarring (odds ratio 4.0, P=0.024). Although renal scarring is not common in low-grade reflux patients, there may be scarring in some patients. DD polymorphism of the ACE gene is a significant risk factor in low-grade reflux patients with renal scarring.

Influence of genetic polymorphisms of the renin-angiotensin system on IgA nephropathy

BACKGROUND

We evaluated the impact of the three major genetic polymorphisms of the renin-angiotensin system [angiotensinogen (AGT) gene M235T, angiotensin-converting enzyme (ACE) gene-I/D and angiotensin II-type 1 receptor (AT1R) gene A1166C polymorphisms] as risk factors in IgA nephropathy.

METHODS

The clinical course of 107 patients with biopsy proven IgA nephropathy followed up for 6.6 +/- 5.8 years was examined. The genetic polymorphisms were determined by PCR amplification.

RESULTS

The allele frequencies of the polymorphisms studied were similar in patients and control subjects. AGT-M235T genotype was associated with the presence of nephrotic syndrome (p < 0.05), correlated to the number of antihypertensive drugs agents taken (p < 0.01) and influenced the rate of deterioration of renal function (p < 0.05). Combined analysis of AGT-M235T and ACE-I/D polymorphisms detected an interaction on affecting progression (p < 0.05). ACE-inhibition had a more pronounced effect in certain AGT-M235T and ACE-I/D genotypes (p < 0.05) and their combined analysis showed a synergistic effect (p < 0.01). No association between AT(1)R-A1166C polymorphism and any of the parameters studied was observed.

CONCLUSIONS

Our results suggest that angiotensinogen-M235T polymorphism is an important marker of progression in IgA nephropathy in Caucasian patients, especially when analyzed in combination with ACE-I/D polymorphism.

Angiotensin-converting enzyme gene insertion/deletion polymorphism in children with Henoch-Schonlein purpua nephritis

This study investigated the relationship between angiotensin-converting enzyme (ACE) gene insertion/deletion polymorphism and the occurrence, severity, prognosis of HSPN. The polymorphism of ACE gene in 103 HSPN cases and 100 healthy children was studied by using the polymerase chain reactions (PCR). Its relation to the clinical manifestation, pathological classification and prognosis of HSPN was analyzed accordingly. The results showed that: (1) there was a significantly higher frequency for DD genotype in HSPN children (P<0.01); (2) DD genotype was more frequently seen in HSPN children with gross hematuria and massive proteinuria (P<0.05), while DI genotype was more common in HSPN children group with renal insufficiency (P<0.05); (3) although mesangial proliferative lesion was most frequently observed in 21 biopsied HSPN children, and DD genotype frequency was still higher in children with severe pathology (Class III IV); (4) II genotype was significantly frequent in HSPN children with complete remission in the follow-up of 32 HSPN children. It was concluded that the deletion allele of ACE gene might play a role, at least to some extent, in the occurrence, deterioration and progression in juvenile HSPN.

Association of angiotensin-converting enzyme polymorphisms with systemic lupus erythematosus and nephritis: analysis of 644 SLE families

Angiotensin II is a strong candidate for the perpetuation of autoimmunity, nephritis and visceral damage in systemic lupus erythematosus (SLE). Our goal was to determine whether angiotensin-converting enzyme (ACE) gene polymorphisms are associated with SLE and/or lupus nephritis (LN). We genotyped 644 SLE patients and 1130 family members for three ACE gene polymorphisms: Alu insertion/deletion (I/D), 23949 (CT)(2/3) and 10698 (G)(3/4). All patients met the American College of Rheumatology (ACR) criteria for SLE, and all LN patients met ACR renal criteria and/or had biopsy evidence of LN. We used the transmission/disequilibrium test (TDT) to examine associations between each polymorphism and SLE, including Caucasian, non-Caucasian, and LN subgroups. We also examined transmission of haplotypes defined by these polymorphisms. The ACE I/D polymorphism was associated with SLE among non-Caucasians (61% transmission, P = 0.026) and the 23949 (CT)(2/3) polymorphism was associated with LN among non-Caucasians (69% transmission, P = 0.014). Several haplotypes defined by these 2 markers demonstrated strikingly increased transmission among non-Caucasians (81% - 66% transmission, P = 0.0046 to 0.010). Due to the choice of study design and analytic method these results are unlikely to be due to population admixture. Our findings suggest that DNA sequence variation in the ACE gene influences the risk of developing SLE and LN.