Publications

UNLABELLED

Among individuals with and without concurrent human immunodeficiency virus (HIV), racial/ethnic differences in the natural history of hepatitis C virus (HCV) have been described. African Americans have lower spontaneous HCV clearance than Caucasians, yet slower rates of liver fibrosis once chronically infected. It is not clear how these differences in the natural history of hepatitis C affect mortality, in either HIV-positive or -negative individuals. We conducted a cohort study of HIV/HCV coinfected women followed in the multicenter Women's Interagency HIV Study to determine the association of self-reported race/ethnicity with all-cause and liver-related mortality. Survival analyses were performed using Cox's proportional hazards models. The eligible cohort (n = 794) included 140 Caucasians, 159 Hispanics, and 495 African Americans. There were 438 deaths and 49 liver-related deaths during a median follow-up of 8.9 years and maximum follow-up of 16 years. African-American coinfected women had significantly lower liver-related mortality, compared to Caucasian (hazard ratio [HR], 0.41; 95% confidence interval [CI]: 0.19-0.88; P = 0.022) and Hispanic coinfected women (HR, 0.38; 95% CI: 0.19-0.76; P = 0.006). All-cause mortality was similar between racial/ethnic groups (HRs for all comparisons: 0.82-1.03; log-rank test: P = 0.8).

CONCLUSIONS

African-American coinfected women were much less likely to die from liver disease, as compared to Caucasians and Hispanics, independent of other causes of death. Future studies are needed to investigate the reasons for this marked racial/ethnic discrepancy in liver-related mortality.

Microbiota are essential for weight gain in mouse models of diet-induced obesity (DIO), but the pathways that cause the microbiota to induce weight gain are unknown. We report that mice deficient in lymphotoxin, a key molecule in gut immunity, were resistant to DIO. Ltbr(-/-) mice had different microbial community composition compared to their heterozygous littermates, including an overgrowth of segmented filamentous bacteria (SFB). Furthermore, cecal transplantation conferred leanness to germ-free recipients. Housing Ltbr(-/-) mice with their obese siblings rescued weight gain in Ltbr(-/-) mice, demonstrating the communicability of the obese phenotype. Ltbr(-/-) mice lacked interleukin 23 (IL-23) and IL-22, which can regulate SFB. Mice deficient in these pathways also resisted DIO, demonstrating that intact mucosal immunity guides diet-induced changes to the microbiota to enable obesity.