Mapping the gut flora of HIV patients can lead to new therapies

Hello there Jan Vesterbacka, researcher at Karolinska Institutet's Department of Medicine, Huddinge, who will soon be defending his thesis on the part played by gut flora in HIV patients’ immune systems. What has your research shown?

"In untreated HIV patients, bacterial components leak out from the gut into the blood in a process called microbial translocation, which activates the immune system and contributes to inflammation. Such inflammation in HIV patients increases the risk of complications like cardiovascular disease and cognitive problems. I’ve been able to show that anti-retroviral drugs reduce the microbial translocation and that antibiotics can probably diminish the inflammation more effectively. I also observed that HIV patients who have not yet received anti-retroviral drugs have a gut flora, or microbiome, that is less species diverse than healthy controls and that the difference in the bacterial flora persisted even after a year of treatment. Additionally, I investigated the gut flora of so-called “elite controllers”, who are HIV patients that can control their virus without drugs for 20 or 30 years with no impairment of their immune system. This rare group of HIV patients had the same species diversity in their microbiota as HIV negative people as well as some unique bacteria that were over-represented. When I examined how the gut flora of elite controllers works biologically, I found that there were proportionally fewer bacteria that break down carbohydrates and a higher percentage involved in fat metabolism. We hypothesize that their unique gut flora helps them control their virus."

What does your research mean for HIV patients?

"We hope that one day it will be possible to study the gut flora of HIV patients and adjust or modulate it using faecal transplantation to introduce a tailored, healthy microbiome. This is currently an established treatment for recurrent Clostridium difficile intestinal infection, which is caused by a microbiome dysbiosis. Faecal transplantation is also being tried for other diseases involving abnormal gut flora. Clinical trials have been performed on giving probiotics to HIV patients, although without significant effect. Maybe progress can be made here."

What contribution do you hope your research will make?

"I hope that what we learn about the gut flora and the immune system can also be useful to other diseases. In the past four or five years, scientists have correlated microbiome changes to several inflammatory and autoimmune diseases, such as MS (multiple sclerosis)."

What interested you in the subject?

"I’d been working for a few years with HIV patients at the infection clinic when it was found that microbial translocation was an important factor behind harmful HIV inflammation. This was in 2006 and I thought it was interesting, and figured that here was something long term that could be done for the patients."

What will you do now?

"I’ll continue to study our patients searching for bacterial metabolites as to explain the findings we’ve made investigating their microbiome. It’s still too early to start modulating the microbiome of HIV patients to any great degree since we don’t know exactly which bacteria to introduce or how to do it."

Text: Maja Lundbäck