Leaky gut linked to autoantibody production in HIV patients

Investigators at the Medical University of South Carolina in Charleston found that autoantibody production in human immunodeficiency virus (HIV)-positive patients who have undergone antiretroviral therapy is linked to levels of Staphylococcus aureus products in their blood, according to a new study published in the journal Microbiome.

The study compared autoantibody production in HIV-positive patients and healthy individuals before and after receiving a seasonal flu vaccine. Patients provided blood samples before vaccination and one and two weeks after. The blood samples were tested using a 125-autoantibody array panel.

Wei Jiang, MD, associate professor in the Department of Microbiology and Immunology at the university, and her team reported that HIV-positive, antiretroviral therapy (ART) patients with high levels of autoantibodies also have increased levels of bacteria, Staphylococcus, products in their blood. This is the same bacteria responsible for skin staph infections, researchers said. Some HIV-positive patients have a higher baseline level of these bacterial products in their system. The team examined other strains of bacteria but linked only Staphylococcus to autoantibody production in HIV-positive individuals.

HIV attacks the immune system, making affected individuals more susceptible to infections. When patients with HIV are treated with ART, their immune system can recover, but some of them produce self-destructive proteins, or autoantibodies. Instead of attacking foreign invaders such as bacteria or viruses, some autoantibodies attack the body's own cells, an autoimmune response.

A "leaky gut" could explain the increased level of Staphylococcus products in the blood of HIV-positive patients, researchers say. In patients with leaky gut, the intestinal lining is weakened, enabling bacteria and toxic products in the gut to enter the bloodstream, where they become vulnerable to the immune system. The immune system's attacks on these bacteria could also injure the body's own tissues. Leaky gut is associated with persistent inflammation and several chronic illnesses, including HIV, irritable bowel syndrome, celiac disease, and type 1 diabetes.

To verify their findings, Jiang and her team injected heat-killed Staphylococcus bacteria into healthy mice and found that they did in fact stimulate autoantibody production. The ability to further explore clinical findings in an animal model was crucial to this study. The mouse study showed that injection of Staphylococcus bacteria stimulates autoantibody production.

Going forward, Jiang and her team said they hope to design a drug that inhibits Staphylococcus to help prevent autoimmunity in HIV patients receiving ART.