Gut bacteria may contribute to HIV infection

Certain bacteria">gut bacteria, including one required for a healthy gut microbiome, differ between people who develop HIV infection and those who do not, according to new UCLA-led research.

The findings, published in the peer-reviewed journal eBioMedicine, suggest that the gut microbiome may influence one's risk of HIV infection, according to study lead Dr Jennifer Fulcher, assistant professor of medicine, division of infectious diseases, at UCLA.

"This is an important area that needs further research to better understand if and how these bacteria could affect HIV transmission," said Fulcher, who also has an appointment with VA Greater Los Angeles Healthcare System. "Microbiome-based therapies are becoming a hot area of research with great potential. With further research, this could be a novel way to help in HIV prevention."

According to Fulcher, there is a link between chronic HIV and changes in bacteria">gut bacteria. The researchers wanted to learn more about when these changes begin to occur after HIV infection.

To that end, they examined gut microbiome samples collected both before and after infection from 27 men who have sex with men. They then compared those samples to those of 28 men who had similar behavioural risk factors for infection but did not have HIV.

The samples were obtained from the UCLA-led Collaborating Consortium of Cohorts Producing NIDA Opportunities (C3PNO), a resource and data centre for millions of pieces of research, lab samples, statistics, and other data aimed at accelerating research into the effects of substance abuse on HIV/AIDS.

The researchers discovered that there was very little change in the bacteria">gut bacteria of the infected men during the first year. They discovered, however, that HIV-infected men had pre-existing differences in bacteria">gut bacteria before becoming infected, compared to their uninfected counterparts.

When compared to uninfected at-risk controls, these men had lower levels of Bacteroides species, a type of bacteria prevalent in the lower intestinal tract that has important metabolic functions in maintaining a healthy gut environment, and higher levels of Megasphaera elsdenii, whose role in the human gut is unknown. Prior to infection, men who acquired HIV had elevated inflammatory cytokines and bioactive lipids, both of which are associated with systemic inflammation, indicating that their bodies were constantly on the defensive against infection or injury, according to the researchers.

The study's limitations include small sample size and a focus on only young men who have sex with men, the majority of whom use drugs, which may limit its generalizability to other populations.