Abstract P386: Associations of Gut Microbiome, but Not Microbial Metabolites, With Hypertension Differ by Race: Findings From the Baltimore Longitudinal Study of Aging
Authors: Tilves Curtis , Tanaka Toshiko , Differding Moira K , Spira Adam , Chia Chee , Ferrucci Luigi , Mueller Noel 
Published: May 2024

Introduction:
Social determinants of health (SDoH) are thought to drive race disparities in hypertension (HTN) and in the gut microbiome (GMB). Additionally, studies suggest that associations of GMB and microbial metabolites with HTN differ by race. Whether this effect modification persists after accounting for SDoH factors has not been investigated.

Hypothesis:
Race-specific associations of GMB and microbial metabolites with HTN are attenuated when accounting for SDoH factors.

Methods:
We selected N=100 Baltimore Longitudinal Study of Aging participants for a fecal metabolomics study. We grouped participants by self-reported race (Black or White) and HTN status (HTN: SBP/DBP ≥ 130/80 mmHg without anti-HTN medication vs. normal blood pressure: SBP/DBP &lt; 120/80), with matching on age, sex, and BMI category. After removal for missing SDoH data, we had N=95 participants for analysis. Metabolon measured fecal metabolites using their global, untargeted panel. Diversigen measured fecal GMB features (diversity, composition, and functional potential) using shotgun metagenomic sequencing. We tested univariable and multivariable associations of GMB alpha diversity and microbial metabolites with HTN using logistic regression, GMB beta diversity with HTN using PERMANOVA, and microbial species and functional potential with HTN using ANCOM-BC and MaAsLin2 methods, respectively. We analyzed associations overall and stratified by race. We adjusted for upstream (employed for pay, income meets needs, marital status, household size, educational attainment) and midstream (stress and depression scores, alternative healthy eating index, total calories, physical activity, smoking, and having private health insurance) SDoH factors.

Results:
HTN groups did not differ by age (66.3±11.1 years), sex (N=62/95 female), BMI (28.6±4.9 kg/m
2
), or race (N=45/95 Black). Carnitine, a precursor for bacterial trimethylamine N-oxide (TMAO), was inversely associated with HTN (OR: 0.30; 95%CI [0.13,0.61]) and was not modified by race. Among GMB features, abundance of
Roseburia intestinalis
was lower among those with HTN (logfold-change [LFC]: -3.53, p=0.0132). Race modified associations of GMB evenness and Shannon diversity with hypertension, with effects generally being stronger among White participants (e.g.: Shannon Black OR [95%CI]: 0.99 [0.59,1.65]; White OR [95%CI]: 1.33 [0.87,2.86], interaction p=0.0242). Race also modified associations of bacterial species with HTN, including
Roseburia intestinalis,
which was stronger for White (LFC: -4.44) than for Black (LFC: -0.40) participants. Adjustment for SDoH factors did not attenuate effect modification of associations by race.

Conclusions:
In our study, which was balanced on race and HTN status (without medications), race modified associations of GMB diversity and composition with HTN, and this was not attenuated by SDoH factors.