Abstract P277: Lower Gut Microbial Diversity in Non-alcoholic Fatty Liver Disease: Results From the Hispanic Community Health Study/Study of Latinos (HCHS/SOL)
Authors: Williams-Nguyen Jessica S , Kuniholm Mark H , Wang Zheng , Chai Jin Choul , Moon Jee-Young , Wang Tao , Isasi Carmen R , Kizer Jorge R , Cotler Scott J , Daviglus Martha L , Knight Rob , Burk Robert D , Qi Qibin , Kaplan Robert C 
Published: March 2020

Introduction:
Nonalcoholic fatty liver disease (NAFLD) is associated with obesity and a leading cause of chronic liver disease in the United States (US). Prevalence of both conditions is higher in US Hispanics/Latinos compared to non-Hispanic whites. Composition of the gut microbiome, comprising the microorganisms in the gastrointestinal tract, has been associated with both NAFLD and obesity in animal and human studies, but there is currently no consensus on which microbial changes are associated with these two conditions. Data on the relation of the gut microbiome with NAFLD in Hispanic/Latino populations are limited.

Hypothesis:
We hypothesized that gut bacterial diversity is associated with NAFLD in Hispanic/Latino adults.

Methods:
This analysis included 2587 Hispanic/Latino adults in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) with fecal samples. The gut microbiome was characterized using shotgun metagenomic sequencing and taxonomic classification by the SHOGUN pipeline with the RefSeq 82 prokaryotic genome database. NAFLD was defined based on gender-specific liver function test thresholds developed in the National Health and Nutrition Examination Survey (NHANES) after excluding participants with other known causes of liver dysfunction. Alpha and beta diversity were compared between groups defined by NAFLD and obesity using multinomial logistic regression and PERMANOVA, respectively. The difference in relative abundance for the 15 most abundant species were compared using the Wilcoxon rank sum test.

Results:
There were 395 (15%) NAFLD cases among 2587 participants, and 1718 (66%) were women. Prevalence of obesity (BMI ≥ 30) was 58% and 42% among those with and without NAFLD, respectively. Higher bacterial alpha diversity (Shannon index) was associated with lower odds of NAFLD with (OR = 0.58, p = 0.0005) or without obesity (OR = 0.70, p = 0.04) compared to participants with neither condition after adjusting for age, gender, Hispanic background, diabetes, dyslipidemia and hypertension. In the same model, higher Shannon index was also associated with lower odds of obesity in the absence of NALFD (OR = 0.78, p = 0.01). Beta diversity (Bray-Curtis) did not differ significantly by NAFLD/obesity groups (p = 0.78) or by NAFLD alone (p = 0.30). Among the 15 most abundant species across samples, 4 (
Bacteroides uniformis
,
Odoribacter splanchnicus
,
Oscillibacter
sp. ER4, and
Alistipes shahii
) had significantly lower abundance in those with NAFLD compared to those without NAFLD irrespective of obesity.

Conclusion:
This study reveals that bacterial alpha diversity but not beta diversity is independently associated with the related conditions, NAFLD and obesity, in US Hispanic/Latino adults. Future work will explore associations between NAFLD and functional capacity of gut microbial components as well as considering relevant host genetic variants in this population.