ACE gene insertion/deletion polymorphism and renal scarring in children with urinary tract infections

Genetic polymorphisms associated with urinary tract infection in children and adults: a systematic review and meta-analysis

INTRODUCTION

The lifetime risk of urinary tract infection is known from first-degree relative studies to be highly heritable. Associations have also been observed across the life course from pediatric urinary tract infection to recurrent urinary tract infection in adulthood, suggesting lifelong susceptibility factors. Candidate gene studies and genome-wide association studies have tested for genetic associations of urinary tract infection; however, no contemporary systematic synthesis of studies is available.

OBJECTIVE

We conducted a systematic review to identify all genetic polymorphisms tested for an association with urinary tract infection in children and adults; and to assess their strength, consistency, and risk of bias among reported associations.

DATA SOURCES AND STUDY ELIGIBILITY CRITERIA

PubMed, HuGE Navigator and Embase were searched from January 1, 2005 to November 16, 2023, using a combination of genetic and phenotype key words.

STUDY APPRAISAL AND SYNTHESIS METHODS

Fixed and random effects meta-analyses were conducted using codominant models of inheritance in metan. The interim Venice criteria were used to assess their credibility of pooled associations.

RESULTS

After removing 451 duplicates, 1821 studies reports were screened, with 106 selected for full-text review, 22 were included in the meta-analysis (7 adult studies and 15 pediatric studies). Our meta-analyses demonstrated significant pooled associations for pediatric urinary tract infection with variation in CXCR1, IL8, TGF, TLR4 and VDR; all of which have plausible roles in the pathogenesis of urinary tract infection. Our meta-analyses also demonstrated a significant pooled association for adult urinary tract infection with variation in CXCR1. All significant pooled associations were graded according to their epidemiological credibility, sample sizes, heterogeneity between studies, and risk of bias.

CONCLUSION

This systematic review provides a current synthesis of the known genetic architecture of urinary tract infection in childhood and adulthood; and should provide important information for researchers analysing future genetic association studies. Although, overall, the credibility of pooled associations was weak, the consistency of findings for rs2234671 single nucleotide polymorphisms of CXCR1 in both populations suggest a key role in the urinary tract infection pathogenesis.

Association between angiotensin converting enzyme gene insertion/deletion polymorphism and renal scar risk in children vesicoureteral reflex: a reappraise meta-analysis

Vesicoureteral reflex(VUR) is a common disease in children. Some studies indicated that the angiotensin converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism associated with the renal scar in VUR, but not all researchers agreed with it. To clarify the effect of ACE I/D polymorphism on renal scar risk in children with VUR, we performed the present meta-analysis. PubMed, CNKI, CBM, and Embase databases were searched for studies that examined the relationship between ACE I/D polymorphism and renal scar risk in children with VUR. The Stata 12.0 software was used for statistical analyses. 11 case-control studies with 1,032 VUR patients were analyzed. The results showed that the DD genotype and D allele were associated with renal scar risk in overall VUR patients, DD vs. DI + II: OR = 1.61, 95% CI = 1.04–2.49, P = 0.03; DD vs. II: OR = 1.78, 95% CI = 1.20–2.65, P < 0.01; D vs. I: OR = 1.38, 95% CI = 1.02–1.86, P = 0.04. Similar results were revealed in Turks, but not in Caucasians and Asians. Our meta-analysis indicated that the ACE DD genotype may increase the risk of renal scar in children with VUR.

Angiotensin Converting Enzyme Gene Insertion/Deletion Polymorphism and Vesicoureteral Reflux in Children: A Meta-Analysis of 14 Case-Control Studies

Vesicoureteral reflux (VUR) is a common and serious urinary disease in children. It usually causes renal scar, urinary tract infection, and chronic renal failure. Previous studies showed the angiotensin converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism might be associated with VUR; however, the conclusions were inconsistent. Therefore we used the meta-analytic approach to clarify the effect of ACE I/D polymorphism on VUR risk.We systematically searched the PubMed, CNKI, and EMBASE databases to identify all the potentially related studies published up to February 4, 2015. Two reviewers independently selected studies and extracted data. The strength of the association was assessed using odd ratio (OR) with its 95% confidence interval (CI) based on fixed or random effects model. The STATA 12.0 software was used for data analysis.A total of 14 case-control studies involving 1197 VUR patients and 1320 healthy controls met the eligibility criteria. Results of meta-analysis showed significant association between ACE I/D polymorphism and VUR risk (D vs. I: OR = 1.28, 95% CI = 1.06-1.54, P = 0.01; DD vs. II: OR = 1.44, 95% CI = 1.12-1.85, P = 0.01; DD vs. DI + II: OR = 1.49, 95% CI = 1.23-1.79, P < 0.01; DD + DI vs. II: OR = 1.20, 95% CI = 0.84-1.72, P = 0.31). Subgroup analyses revealed varied results. In Turkish people, results of all the genetic models other than DI vs. II showed statistical significance; in Caucasians, DD vs. DI + II showed statistical significance; and in Asians, DI versus II showed statistical significance.Our meta-analysis indicated that the ACE I/D polymorphism might be associated with increased risk of VUR in children. However, due to the limitations, we suggest conducting additional studies with larger sample size and adjustment for various risk factors, in the future for further clarification.

Impact of common functional polymorphisms in renin angiotensin system genes on the risk of renal parenchymal scarring following childhood urinary tract infection

BACKGROUND

Pathogenesis of renal parenchymal scarring (RPS) after acute pyelonephritis (APN) is unclear. The risk of RPS varies markedly among individuals, suggesting a genetic role.

OBJECTIVE

To investigate a possible role of common polymorphisms in renin angiotensin system genes in APN-associated RPS in children.

PATIENTS AND METHODS

This study included 104 APN children and 300 controls. APN was diagnosed by urine culture and typical findings on 99Tc-DMSA scans. Voiding cystourethrogram tested the presence of vesicoureteral reflux (VUR). Follow-up DMSA scans were performed 4-6 months later to identify new RPS. Angiotensin converting enzyme gene I/D, angiotensin II receptor type-1 A1166C and angiotensinogen M235T polymorphisms were genotyped.

RESULTS

New RPS developed in 44.2% (46/104) of children with APN. VUR was diagnosed in 35.6% (37/104) of APN cases. RPS developed in 73% of cases of VUR. The D allele of ACE gene I/D polymorphism was significantly more common in APN cases with RPS (73.91%) than non-RPS (58.6%) and controls (54.5%) (p = 0.021, p = 0.002, respectively). The AGTR-1 A1166C A allele was significantly more common in VUR than the non-reflux children (91.9% versus 76.1%; p = 0.005). VUR, in contrast to the D allele (OR 6.1, 95% CI 0.878-19.7; p = 0.05), was an independent risk factor for RPS.

DISCUSSION

ACE gene D allele is associated with a twofold increase in RPS risk, which could be a result of a functional effect to increase tissue levels and activity of ACE during APN. However, D allele failed to qualify as an independent risk and its RPS association could be dependent on other co-factors, such as TGFβ1 activation, or the D-allele might link with recently discovered functional polymorphisms at the 5' end of the ACE gene. Although VUR is an independent risk for RPS, it is not clear whether this is due to exposure of the kidneys to infected urine, or VUR-associated dysplasia. In contrast with published literature, we noted higher rates of RPS and high-grade VUR, suggesting a more aggressive VUR course or local unawareness of APN. Our study has its limitations; the small number of VUR children, and the clinical and ethical difficulties of testing VCUG and DMSA in controls.

CONCLUSIONS

ACE gene D allele is associated with, but cannot independently predict, RPS in children. VUR is an independent risk for post-pyelonephritic scarring. AGTR-1 1166A/C polymorphism is associated with occurrence, but not progression, of VUR.

Angiotensin-converting enzyme polymorphism affects outcome of local Chinese with acute lung injury

INTRODUCTION

Acute Lung Injury (ALI) with genetic predisposition is fatal. Relationship between angiotensin-converting enzyme insertion/deletion (ACE I/D) polymorphism and the prognosis of local Chinese patients with ALI was investigated; meanwhile, the mechanisms involved were explored.

METHODS

101 ALI patients, 408 non-ALI patients and 236 healthy blood donors were enrolled. ACE I/D polymorphism was detected by polymerase chain reaction, then ACE genotype (II, ID, DD) and allele (I, D) frequencies were compared. Clinical data of ALI patients was calculated. Also, peripheral blood mononuclear cells (PBMC) were isolated from healthy volunteers with different ACE genotypes. Lipopolysaccharide (LPS)-induced ACE gene mRNA expression and ACE activity was measured.

RESULTS

There was no significant difference in the frequencies of the genotypes and alleles. Acute Physiology and Chronic Health Evaluation (APACHE) II score was higher in DD subgroup than in II subgroup (19.7 ± 8.7 and 15.6 ± 6.2; P < 0.05). The 28-day mortality was significantly different (17.4%, 26.8%, and 64.3% for II, ID, and DD; P = 0.013). DD genotype was the independent prognostic factor for 28-day outcome. Furthermore, LPS-induced ACE mRNA expression and ACE activity from PBMC in DD genotype subgroup were both significantly higher than those in the other two subgroups.

CONCLUSIONS

ACE I/D polymorphism is a prognostic factor for ALI. Patients with the DD genotype have higher mortality of ALI. Polymorphism influences the expression of ACE gene in LPS-stimulated PBMC, DD genotype leads to higher level of mRNA and enzyme activity. It may be one of the mechanisms involved.

Genetics of innate immunity and UTI susceptibility

A functional and well-balanced immune response is required to resist most infections. Slight dysfunctions in innate immunity can turn the 'friendly' host defense into an unpleasant foe and give rise to disease. Beneficial and destructive forces of innate immunity have been discovered in the urinary tract and mechanisms by which they influence the severity of urinary tract infections (UTIs) have been elucidated. By modifying specific aspects of the innate immune response to UTI, genetic variation either exaggerates the severity of acute pyelonephritis to include urosepsis and renal scarring or protects against symptomatic disease by suppressing innate immune signaling, as in asymptomatic bacteriuria (ABU). Different genes are polymorphic in patients prone to acute pyelonephritis or ABU, respectively, and yet discussions of UTI susceptibility in clinical practice still focus mainly on social and behavioral factors or dysfunctional voiding. Is it not time for UTIs to enter the era of molecular medicine? Defining why certain individuals are protected from UTI while others have severe, recurrent infections has long been difficult, but progress is now being made, encouraging new approaches to risk assessment and therapy in this large and important patient group, as well as revealing promising facets of 'good' versus 'bad' inflammation.

Genetic susceptibility to renal scar formation after urinary tract infection: a systematic review and meta-analysis of candidate gene polymorphisms

Identifying patients who may develop renal scarring after urinary tract infections (UTI) remains challenging, as clinical determinants explain only a portion of individual risk. An additional factor that likely affects risk is individual genetic variability. We searched for peer-reviewed articles from 1980 to December 2009 in electronic databases that reported results showing an association between gene polymorphims and renal scaring after UTI. Two independent researchers screened articles using predetermined criteria. Studies were assessed for methodological quality using an aggregate scoring system. The 18 studies ultimately included in the review had investigated 16 polymorphisms in nine genes in association with renal scarring formation after UTI. Based on the predetermined criteria for assessing the quality of the studies, 12 studies (67%) were identified as being of poor quality design. A meta-analysis of cumulative studies showed on association between renal scarring formation after UTI and the angiotensin converting enzyme insertion/deletion polymorphism [ACE I/D; recessive model for D allele; odds ratio (OR) 1.73, 95% confidence interval (CI) 1.09-2.74, P = 0.02] or transforming growth factor (TGF)-β1 c.-509 T > C polymorphism (dominant model for T allele; OR 2.24, 95% CI 1.34-3.76, P = 0.002). However, heterogeneity among studies was large, indicating a strong difference that cannot only be explained by differences in study design. The studies reviewed in this article support a modest involvement of the vasomotor and inflammatory genes in the development of renal scarring after UTIs. This review also shows that only few possible candidate genes have been investigated for an association with renal scarring, raising the hypothesis that some gene polymorphisms may exert their effects through an interaction with as yet uninvestigated factors that may be related to geographic and/or socio-economic differences.

Cholangitis of Pancreatitis? Does the Angiotensin-Converting Enzyme Genotype Favor Either?

Acute cholangitis and pancreatitis are serious complications of gallstones, with considerable morbidity and mortality. Angiotensin-converting enzyme (ACE) is an exopeptidase that is important in regulating blood pressure, metabolizing bradykinin and in maintaining an inflammatory response. To determine whether the ACE genotype determines occurrence of cholangitis or pancreatitis we examined ACE I/D genotypes in 31 patients who had cholangitis, 44 patients with biliary pancreatitis and 157 healthy individuals. The patients had been hospitalized at the Department and Intensive Care Faculty of Medicine, Ege University, Izmir, Turkey. The patients were recalled 4 years later and their prognosis was evaluated. The ACE II genotype was found at a higher frequency in the cholangitis and biliary pancreatitis patients when compared with the healthy subjects (p <0.05). There was no significant difference between cholangitis and biliary pancreatitis cases regarding the genotype and allele distribution (p >0.05). Recurrence of infection occurred more frequently in the patients with the DD genotype, although it was not significant according to the first assessment (p >0.05). The ACE gene polymorphism did not seem to favor development of either cholangitis or pancreatitis.