Abstract P189: Metabolomic Signatures Of Serum Creatinine Among Hypertensive African Americans.

Abstract

Background: The prevalence of chronic kidney disease (CKD) in African Americans (AAs) is high. Although ancestry-specific biomarkers have been identified, few translate to the clinic. Metabolomic studies may identify novel biomarkers useful for prevention, diagnosis and treatment. Methods: Plasma from 300 AA Hypertension Genetic Epidemiology Network (HyperGEN) study participants age ≥40 years with serum creatinine (SCr) <2 mg/dL were assayed for an untargeted metabolomic study of SCr using an ultra-high performance liquid chromatography mass spectrometry platform (Metabolon ® ). SCr was measured using a thin-film adaptation of the amidohydrolase enzymatic method on fasting blood samples. Each metabolite was tested for normality and a rank-based inverse normal transformation was performed as appropriate. Multivariable linear regression was used to test for association between the metabolite (outcome) and SCr (exposure of interest) adjusting for age, gender, waist circumference and center. A Bonferroni correction was used to adjust for multiple testing using. The top 25 most significant metabolites were evaluated for replication in 367 participants from the African American-Diabetes Heart Study (AA-DHS). An exploratory pathway analysis was conducted among significant (p< 6.0*10 -5 6.0e -5 metabolites in HyperGEN. Results: Among 300 participants from HyperGEN the mean age was 54.5 years (SD=9.5) and 58.7% were female. Mean SCr was 0.93 (SD=0.25). Eighty percent were treated for hypertension and 28% had diabetes. A total of 809 metabolites were annotated in HyperGEN samples. Of those, 391 were associated with SCr at p<0.05 and 256 metabolites met the Bonferroni significance criteria (p< 6.0*10 -5 ). The top SCr associated metabolites were tartonate(hydroxymalonate)(β[SE]= 2.99[0.07], p=3.98e -117 ), 1-stearoyl-GPC(18:0)(β[SE]= 2.49[0.14], p=2.28e -44 ), 2S-3R-dihydroxybutyrate)(β[SE]= 2.36[0.14],p=1.53e -40 ) and isovalerate(C5)( β[SE]= 2.30[0.15], p = 2.78e -36 ). The association of these metabolites with SCr replicated in AA-DHS [(tartonate(hydroxymalonate)(β[SE]= 0.66[0.19], p=0.001), 1-stearoyl-GPC(18:0)(β[SE]= 1.30[0.20], p=1.61 -10 ), 2S-3R-dihydroxybutyrate)(β[SE]= 1.20[0.18],p=4.69e -11 ) and isovalerate(C5)( β[SE]= 1.24[0.20], p = 1.91e -09 )]. An exploratory pathway analysis highlighted xenobiotics and the lysophospholipid pathway. Significance: Tartronate is a xenobiotic that is related to BMI, insulin resistance and adiponectin. 1-stearoyl-GPC (18:0) is a lysophospholipid metabolite found to be associated with oxidative stress. Conclusion: The current study discovered and replicated metabolites associated with SCr in a population of AAs with a high prevalence of hypertension. If validated, these could provide new insights in kidney disease pathways or aid in the treatment and prevention of CKD in the AA population.