Gut microbes from high risk men (men who have sex with men) were found to drive immune activation in mice and HIV infection in cells, found new study published in PLOS Pathogens by Brent Palmer and Catherine Lozupone of the University of Colorado Anschutz, and colleagues.
The communities of microbes that colonize the human gut play a significant role in shaping the immune system. Whether these gut microbiome differences in high-risk men who have sex with men directly impact immune activation is important to understand because increased T-cell activation is associated with increased HIV transmission risk and more severe disease.
To test the immunological effect of the gut microbiome in men who have sex with men, Palmer and Lozupone transplanted stool from HIV-negative men who have sex with women, HIV-negative high-risk men who have sex with men, and HIV-positive men who have sex with men to germ-free mice. DNA sequencing showed that specific microbiome differences associated with men who have sex with men were successfully engrafted in mice. Moreover, these differences were associated with increased CD4+ and CD8+ T-cell activation in the mice.
The authors conclude, "Gut microbiota from men who have sex with men (MSM) induce activation of HIV target cells when transplanted to mice and stimulate HIV infection of human gut cell cultures. These findings support a role for the gut microbiome in HIV transmission in MSM."