HIV: gut microbiota may increase immune system deficiency

According to an international study, the digestive microbiota of some HIV-positive patients receiving antiretroviral therapy is impaired and leads to a lasting impairment of their immune system.

 

To multiply and survive in the human organism, the human immunodeficiency virus (HIV) infects immune cells called CD4 cells, a type of white blood cells that mediate a protective response. This infection leads to the death of these cells and makes the HIV-positive patients more susceptible to infections.

Impaired immune system

The aim of antiretroviral treatments is to prevent the viral replication process, thus preserving many CD4 cells and allowing them to multiply and protect the organism. However, scientific literature shows that for several patients, CD4 levels climb slowly despite the treatment. A study published at the end of September in Scientific Reports suggests that the imbalance of the gut microbiota could play a role in this process. Researchers came to that conclusion by analyzing stools of 26 HIV-positive men who had been treated for over two years with antiretrovirals (including around 2/3 responders), and 20 healthy volunteers.

Abundance of one specific bacterial group

It emerges from this analysis that the composition of the intestinal flora of the participants is different whether they are infected or not. Furthermore, a specific bacteria group (Fusobacterium) is more abundant in HIV-positive patients with a low intestinal CD4 count (and poor response to treatment). The study revealed that 70% of these patients, on average older than the others, have higher levels of this bacteria compared to the other patients (25% of the other HIV‑positive patients and only 10% of non-infected volunteers). According to the researchers, overabundance of this bacterium in sub-optimal responders could be associated to a slight increase in CD4 levels, and thus to a lasting alteration of the immune system. They believe that modulating the amount of this bacterial group in the intestines could be a mean to strengthen the immune system, especially in sub‑optimal responders that have been under treatment for years.

 

Sources:

Soo Ching Lee, Ling Ling Chua, Siew Hwei Yap, Tsung Fei Khang, Chan Yoon Leng et al. Enrichment of gut-derived Fusobacterium is associated with suboptimal immune recovery in HIV-infected individuals. Scientific Reports, Sep 24, 2018