The intestinal microbiota may influence aids resistance

Vignette

HIV “elite” or “natural” controllers are HIV-positive patients who, without treatment, still do not develop AIDS. A Spanish-Swedish study revealed significant differences in the composition of their intestinal microbiota.

 

In the vast majority of cases, untreated HIV infection leads to AIDS. But in a very small minority of infected patients (less than 1%), called “elite controllers,” the virus does not multiply. And while several genetic factors have already been identified to explain this “protection,” a team of Swedish and Spanish researchers studied the influence of the intestinal microbiota on this peculiarity.

The scientists first compared the composition of the intestinal microbiota of 16 “elite controllers” to 32 HIV-positive “naive progressors,” who had not yet started antiretroviral therapy. There was also a control group of 16 HIV-negative subjects. The researchers noted a much greater bacterial diversity and abundance in the first group. The results showed an increase of around 25% in the number of different bacterial genera observed, and a change in the abundance of certain genera known to have regulatory effects on the immune system, like Succinivibrio, Sutterella et Oscillospira.

Functional analysis more precisely identified the metabolic mechanisms by which these differences may modulate the patients’ immune defenses, such as the metabolism of tryptophan, whose plasma concentration seems to be stable in “elite controllers,” while it increases in other patients as the infection spreads.

 

Sources
Vesterbacka J et al. Richer gut microbiota with distinct metabolic profile in HIV infected Elite Controllers. Sci Rep. 2017 Jul 24; 7(1):6269.