COMT-Val158Met-polymorphism is not a risk factor for acute kidney injury after cardiac surgery

Cardiac Surgery-Associated Acute Kidney Injury

AKI is a common and serious complication of cardiac surgery that has a significant impact on patient morbidity and mortality. The Kidney Disease Improving Global Outcomes definition of AKI is widely used to classify and identify AKI associated with cardiac surgery (cardiac surgery-associated AKI [CSA-AKI]) on the basis of changes in serum creatinine and/or urine output. There are various preoperative, intraoperative, and postoperative risk factors for the development of CSA-AKI which should be recognized and addressed as early as possible to expedite its diagnosis, reduce its occurrence, and prevent or ameliorate its devastating complications. Crucial issues are the inaccuracy of serum creatinine as a surrogate parameter of kidney function in the perioperative setting of cardiothoracic surgery and the necessity to discover more representative markers of the pathophysiology of AKI. However, except for the tissue inhibitor of metalloproteinase-2 and insulin-like growth factor binding protein 7 ratio, other diagnostic biomarkers with an acceptable sensitivity and specificity are still lacking. This article provides a comprehensive review of various aspects of CSA-AKI, including pathogenesis, risk factors, diagnosis, biomarkers, classification, prevention, and treatment management.

Diagnosis, pathophysiology and preventive strategies for cardiac surgery-associated acute kidney injury: a narrative review

Acute kidney injury (AKI) is a common and serious complication of cardiac surgery and is associated with increased mortality and morbidity, accompanied by a substantial economic burden. The pathogenesis of cardiac surgery-associated acute kidney injury (CSA-AKI) is multifactorial and complex, with a variety of pathophysiological theories. In addition to the existing diagnostic criteria, the exploration and validation of biomarkers is the focus of research in the field of CSA-AKI diagnosis. Prevention remains the key to the management of CSA-AKI, and common strategies include maintenance of renal perfusion, individualized blood pressure targets, balanced fluid management, goal-directed oxygen delivery, and avoidance of nephrotoxins. This article reviews the pathogenesis, definition and diagnosis, and pharmacological and nonpharmacological prevention strategies of AKI in cardiac surgical patients.

Genetic Susceptibility to Acute Kidney Injury

Acute kidney injury (AKI) is a widely held concern related to a substantial burden of morbidity, mortality and expenditure in the healthcare system. AKI is not a simple illness but a complex conglomeration of syndromes that often occurs as part of other syndromes in its wide clinical spectrum of the disease. Genetic factors have been suggested as potentially responsible for its susceptibility and severity. As there is no current cure nor an effective treatment other than generally accepted supportive measures and renal replacement therapy, updated knowledge of the genetic implications may serve as a strategic tactic to counteract its dire consequences. Further understanding of the genetics that predispose AKI may shed light on novel approaches for the prevention and treatment of this condition. This review attempts to address the role of key genes in the appearance and development of AKI, providing not only a comprehensive update of the intertwined process involved but also identifying specific markers that could serve as precise targets for further AKI therapies.

Influence of ADRB1, ADRB2, and COMT Genetic Polymorphisms on Postoperative Outcomes of Patients Undergoing Cardiac Valve Surgery

PURPOSE

The aim of this study is to prospectively investigate the influence of ADRB and COMT gene polymorphisms on postoperative outcomes of patients undergoing cardiac surgery.

METHODS

This prospective cohort study included 223 patients undergoing elective cardiac valve surgery using cardiopulmonary bypass. Demographic information, intraoperative data, postoperative data, and blood samples were collected. Patients were genotyped for single-nucleotide polymorphisms (SNPs) of ADRB1 rs1801253, ADRB2 rs1042713, and COMT rs4680. Major adverse cardiovascular and cerebrovascular events (MACCEs) were used as the primary outcome to evaluate the postoperative prognosis of patients. Secondary outcomes included the duration of mechanical ventilatory support, intensive care unit stay, postoperative hospital stay, and postoperative need of inotropic or vasoactive agents.

FINDINGS

The overall incidence of MACCEs was 15.2%. Among 3 SNP loci, only different genotyped carriers of ADRB2 rs1042713 had statistically significant differences in the incidence of MACCEs (P = 0.005), especially for acute kidney injury (P = 0.023). The proportions of postoperative norepinephrine demand of patients carrying the AA genotype of ADRB2 rs1042713 (P = 0.016) and the AG genotype of COMT rs4680 (P = 0.018) were low. The duration of mechanical ventilatory support (P = 0.034) and postoperative hospital stay (P = 0.045) of patients carrying the AG genotype of COMT rs4680 was shortest. After multiple logistic regression analysis, we found that the G allele carriers of ADRB2 rs1042713 had a higher risk of MACCEs (AG vs AA genotype: odds ratio [OR] = 4.348; 95% CI, 1.529-12.359, P = 0.006; GG vs AA genotype: OR = 3.722; 95% CI, 1.060-13.071; P = 0.040), in particular with acute kidney injury (AG vs AA genotype: OR = 5.273; 95% CI, 1.093-25.451; P = 0.038; GG vs AA genotype: OR = 7.533; 95% CI, 1.275-44.522; P = 0.026). There was no SNP-SNP interaction found among the 3 SNPs with multifactor dimensionality reduction analysis.

IMPLICATION

The ADRB2 rs1042713 polymorphism might be related to prognosis of patients undergoing cardiac surgery. Patients carrying the G allele of ADRB2 rs1042713 had a higher risk of developing MACCEs, especially acute kidney injury. chictr.org.com identifier: ChiCTR1800015105.

Effects of ECE-1b rs213045 and rs2038089 polymorphisms on the development of contrast-induced acute kidney injury in patients with acute coronary syndrome

OBJECTIVE

Endothelin-1 (ET-1) promotes the progression and induction of sclerotic renal changes in end-stage kidney disease. Membrane-bound endothelin-converting enzyme 1 (ECE-1) is involved in the production of ET-1. The aim of this study was to assess the effects of ECE-1b rs213045 and rs2038089 polymorphisms, which have been shown to be involved in the development of atherosclerosis, hypertension, and nephropathy, on the development of contrast-induced acute kidney injury (CI-AKI) in patients with acute coronary syndrome.

METHODS

Our study included 38 patients with CI-AKI (CI-AKI[+]) and 55 patients without CI-AKI (CI-AKI[-]) who had coronary syndrome. The ECE-1b polymorphisms rs213045 and rs2038089 were assessed using real-time PCR. Serum ET-1 levels were measured by ELISA.

RESULTS

The distributions of ECE-1b rs213045 and rs2038089 polymorphisms were similar between the two groups. Additionally, the serum ET-1 level did not different between the groups and was not associated with the ECE-1b polymorphisms. Peri-procedural low systolic blood pressure (SBP) was identified as a risk factor for CI-AKI development.

CONCLUSION

Our findings indicate that ECE-1b rs213045 and rs2038089 polymorphisms are not associated with CI-AKI development and that peri-procedural low SBP is a risk factor for CI-AKI. However, variations in ECE-1b rs2038089 may contribute to the development of CI-AKI.

The potential impact of COMT gene variants on dopamine regulation and phenotypic traits of ASD patients

Catechol-O-methyltransferase (COMT) enzyme has a major role in the adjustment of catechol-dependent functions, for example, cognition, cardiac function, and pain processing. The pathogenesis of autism may be related to dysfunction in the midbrain dopaminergic system. Therefore, we aimed to clarify how COMT gene variants affect dopamine level, and its potential impact on phenotype traits of autistic patients. 52 autistic patients were subjected to comprehensive clinical investigation, sequencing of exon 4 of the COMT gene by direct Sanger Sequencing, and measuring of dopamine levels. The clinical presentations of autistic subjects were correlated with detected COMT variants and dopamine level. Our molecular results revealed that three COMT variants were found: rs8192488 [C > T], rs4680 (Val158Met) and rs4818 [C > G]. Within autistic subjects, Val158Met rs4680 carriers were significantly distributed (71.2% P = 0.014) accompanied with abnormal dopamine, abnormal Electroencephalogram (EEG) and increasing the severity of autistic behaviour. As regards the haplotypes, CC/VM/CG block was significantly distributed among the autistic subjects (30.8%) presented with low mean dopamine level (15.8 ± 4.7 pg/ml, p = 0.05), while CC/MM/CC were presented with high mean level (77.8 ± 8.6 pg/ml, p = 0.05). Evidence is currently limited and preliminary, further studies are necessary in order to set up a coherent dopaminergic model of Autism Spectrum Disorder (ASD), which would further pave the way for an adequate treatment.

Common Inflammation-Related Candidate Gene Variants and Acute Kidney Injury in 2647 Critically Ill Finnish Patients

Acute kidney injury (AKI) is a syndrome with high incidence among the critically ill. Because the clinical variables and currently used biomarkers have failed to predict the individual susceptibility to AKI, candidate gene variants for the trait have been studied. Studies about genetic predisposition to AKI have been mainly underpowered and of moderate quality. We report the association study of 27 genetic variants in a cohort of Finnish critically ill patients, focusing on the replication of associations detected with variants in genes related to inflammation, cell survival, or circulation. In this prospective, observational Finnish Acute Kidney Injury (FINNAKI) study, 2647 patients without chronic kidney disease were genotyped. We defined AKI according to Kidney Disease: Improving Global Outcomes (KDIGO) criteria. We compared severe AKI (Stages 2 and 3, n = 625) to controls (Stage 0, n = 1582). For genotyping we used iPLEX^TM Assay (Agena Bioscience). We performed the association analyses with PLINK software, using an additive genetic model in logistic regression. Despite the numerous, although contradictory, studies about association between polymorphisms rs1800629 in TNFA and rs1800896 in IL10 and AKI, we found no association (odds ratios 1.06 (95% CI 0.89–1.28, p = 0.51) and 0.92 (95% CI 0.80–1.05, p = 0.20), respectively). Adjusting for confounders did not change the results. To conclude, we could not confirm the associations reported in previous studies in a cohort of critically ill patients.

The COMT-polymorphism is not associated with the incidence of acute kidney injury after cardiac surgery - a prospective cohort study

Background

The Catechol-O-methyltransferase (COMT) represents the key enzyme in catecholamine degradation. Recent studies suggest that the COMT rs4680 polymorphism is associated with the response to endogenous and exogenous catecholamines. There are, however, conflicting data regarding the COMT Met/Met phenotype being associated with an increased risk of acute kidney injury (AKI) after cardiac surgery. The aim of the current study is to prospectively investigate the impact of the COMT rs4680 polymorphism on the incidence of AKI in patients undergoing cardiac surgery.

Methods

In this prospective single center cohort study consecutive patients hospitalized for elective cardiac surgery including cardiopulmonary-bypass (CPB) were screened for participation. Demographic clinical data, blood, urine and tissue samples were collected at predefined time points throughout the clinical stay. AKI was defined according to recent recommendations of the Kidney Disease Improving Global Outcome (KDIGO) group. Genetic analysis was performed after patient enrolment was completed.

Results

Between April and December 2014, 150 patients were recruited. The COMT genotypes were distributed as follows: Val/Met 48.7%, Met/Met 29.3%, Val/Val 21.3%. No significant differences were found for demography, comorbidities, or operative strategy according to the underlying COMT genotype. AKI occurred in 35 patients (23.5%) of the total cohort, and no differences were evident between the COMT genotypes (20.5% Met/Met, 24.7% Val/Met, 25.0% Val/Val, p = 0.66). There were also no differences in the post-operative period, including ICU or in-hospital stay.

Conclusions

We did not find statistically significant variations in the risk for postoperative AKI, length of ICU or in-hospital stay according to the underlying COMT genotype.

Genetic variants and acute kidney injury: A review of the literature

PURPOSE

Limited data exists on potential genetic contributors to acute kidney injury. This review examines current knowledge of AKI genomics.

MATERIALS AND METHODS

32 studies were selected from PubMed and GWAS Catalog queries for original data studies of human AKI genetics. Hand search of references identified 3 additional manuscripts.

RESULTS

33 of 35 studies were hypothesis-driven investigations of candidate polymorphisms that either did not consistently replicate statistically significant findings, or obtained significant results only in few small-scale studies. Vote-counting meta-analysis of 9 variants examined in >1 candidate gene study showed ≥50% non-significant studies, with larger studies generally finding non-significant results. The remaining 2 studies were large-scale unbiased investigations: One examining 2,100 genes linked with cardiovascular, metabolic, and inflammatory syndromes identified BCL2, SERPINA4, and SIK3 variants, while a genome-wide association study (GWAS) identified variants in BBS9 and the GRM7|LMCD1-AS1 intergenic region. All studies had relatively small sample sizes (<2300 subjects). Study heterogeneity precluded candidate gene and GWA meta-analysis.

CONCLUSIONS

Most studies of AKI genetics involve hypothesis-driven (rather than hypothesis-generating) candidate gene investigations that have failed to identify contributory variants consistently. A limited number of unbiased, larger-scale studies have been carried out, but there remains a pressing need for additional GWA studies.

Genetic predisposition to acute kidney injury--a systematic review

BACKGROUND

The risk of an individual to develop an acute kidney injury (AKI), or its severity, cannot be reliably predicted by common clinical risk factors. Whether genetic risk factors have an explanatory role poses an interesting question, however. Thus, we conducted a systematic literature review regarding genetic predisposition to AKI or outcome of AKI patients.

METHODS

We searched Ovid SP (MEDLINE) and EMBASE databases and found 4027 references to AKI. Based on titles and abstracts, we approved 37 articles for further analysis. Nine were published only as abstracts, leaving 28 original articles in the final analysis. We extracted the first author, year of publication, study design, clinical setting, number of studied patients, patients with AKI, ethnicity of patients, studied polymorphisms, endpoints, AKI definition, phenotype, significant findings, and data for quality scoring from each article. We summarized the findings and scored the quality of articles.

RESULTS

The articles were quite heterogeneous and of moderate quality (mean 6.4 of 10).

CONCLUSIONS

Despite different gene polymorphisms with suggested associations with development or severity or outcome of AKI, definitive conclusions would require replication of associations in independent cohort studies and, preferably a hypothesis-free study design.

Pilot study of association of catechol-O-methyl transferase rs4680 genotypes with acute kidney injury and tubular stress after open heart surgery

AIM

To assess the association of genetic variants of catecholamine-O-methyltransferase (COMT) genotypes with acute kidney injury (AKI) and tubular stress after open heart surgery.

PATIENTS & METHODS

We genotyped 195 patients for the COMT-Val158Met polymorphism and measured creatinine, neutrophil gelatinase-associated lipocalin and midkine. We analyzed the association between such polymorphisms and these kidney-related variables.

RESULTS

Nonsignificantly more COMT LL patients developed RIFLE-AKI compared with non-LL patients (p = 0.11). Compared with HL and HH patients, LL patients who developed AKI had lower increases in serum creatinine. COMT LL patients had less pronounced release of tubular stress biomarkers (neutrophil gelatinase-associated lipocalin: p = 0.045, midkine: p = 0.072).

CONCLUSION

COMT genotype may associate with different patterns of renal functional changes and tubular stress biomarker release response after open heart surgery.

Common Variants in LRP2 and COMT Genes Affect the Susceptibility of Gout in a Chinese Population

Gout is a common inflammation disease resulting from an increase in serum uric acid. Nearly 70% of uric acid is excreted via the kidneys. To date, evidence for an association between genetic loci and gout is absent, equivocal or not replicated. Our study aims to test variants in two genes abundantly expressed in the kidney, LRP2 and COMT, for their association with uric acid and gout. In total, 1318 Chinese individuals were genotyped for rs2544390 in LRP2 and rs4680 in COMT. These LRP2 and COMT gene polymorphisms showed no significant effect on uric acid (P = 0.204 and 0.188, separately); however, rs2544390 in LRP2 did influence uric acid levels in individuals with BMI ≥ 25 (P = 0.009). In addition, the allele frequency distributions of the two loci showed a significant difference between gout patients and healthy controls. A missense variation in rs4680 (G > A) decreased the risk of gout (OR = 0.77, P = 0.015), whereas the T allele of rs2544390 was associated with gout pathogenesis risk (OR = 1.26, P = 0.020). The present study provides the first evidence for an association between COMT and gout. Rs2544390 in LRP2 only influenced uric acid levels in individuals with BMI ≥ 25, which might explain the discrepant results among previous studies. In addition, we are the first to identify the association between LRP2 and gout in a Chinese population and to confirm this association in Asians.