According to a new study by researchers at the University of Colorado's Anschutz Medical Campus, a person's sexual behavior could affect their microbiome and immune system, potentially increasing their risk of contracting HIV. The microbiome, a community of microbes in the gut, plays an important role in developing and shaping the human immune system, but recent studies have shown that men who have sex with men (MSM) have very different microbiomes than men who have sex with women. . The Anschutz researchers wanted to know whether this altered microbiome induces T-cell activation, which is linked to the risk of HIV transmission and increased disease severity. To study this, they took stool samples from 35 healthy men who had sex with men and men who had sex with women, and transplanted them into mice.
Mice given the MSM stool samples showed greater evidence of CD4 + T cell activation, putting them at a higher risk of contracting HIV if they were humans. They also isolated immune cells from the intestines of HIV-negative people and exposed them to bacteria from MSM and MSW feces. When the immune cells derived from that of the human gut were exposed to MSM fecal bacteria, they were more likely to be infected with the HIV virus in vitro.
The study's lead author, Brent Palmer, PhD, associate professor of medicine in the Department of Allergies and Clinical Immunology at the CU School of Medicine, claimed that, these results provide evidence of a direct link between microbiome composition and immune activation in HIV-negative and HIV-positive MSM and thus, justifies the study of the gut microbiome as a risk factor for HIV transmission. It is not known exactly why the microbiome of men who have sex with men is so different. Some have theorized that diet can promote inflammation and therefore activate T cells. There is a unique microbiome associated with MSM that drives immune activation in the gut. Though, the reason is still unknown. However, it's important to understand that this microbiome could directly affect the immune system. The study's co-authors are Sam X. Li, PhD, and Catherine Lozupone, PhD, of the University of Colorado's Anschutz Medical Campus.
