Tuberculosis (TB) is among the world’s leading causes of death and is the primary cause of death in people who are HIV-positive. Among the 1.6 million people that died from TB in 2017, around 300,000 of them were HIV-positive, according to the World Health Organization. Researchers at the Texas Biomedical Research Institute have now learned more about why the two diseases are worse when they happen at once. This work, which has been reported in the Journal of Clinical Investigation, may help in the development of better treatments for those who are at risk.
"We were a little surprised at the extent of clarity in our data," noted Professor and Southwest National Primate Research Center Director Deepak Kaushal. "I am actually very excited to move forward trying different treatment approaches on co-infected monkeys."
TB is a bacterial infection caused by Mycobacterium tuberculosis and can spread when an infected person coughs or sneezes and another person breathes that air. TB is more likely to happen in people with weak immune systems, like HIV patients; specifically, HIV targets a type of immune cell called CD4+ cells. This new work indicates that other factors are also at work.
In this study, the scientists used a rhesus macaque model of HIV to show that chronic immune activation in the lung encourages or even causes the progression of the disease. When the body is fighting tough pathogens, immune pathways can produce too many inflammatory molecules like cytokines and chemokines.
"It's like all the taps and faucets in your house are turned on full blast all the time," explained Kaushal. "You are going to lose a lot of water. With this dysfunction, all cytokines ad chemokines are constantly being produced to the highest levels. This dysregulates the body's ability to fight off other infections."
Chronic immune activation happens even when people are controlling their HIV infection with antiretrovirals. Kaushal noted that "we need to develop approaches to target chronic immune activation," perhaps with a drug that would be an additional therapy along with ART.
Learn more about HIV as an inflammatory disorder from the video.