Chronic alcohol consumption modulates a host of immune defense mechanisms and increases susceptibility to infections with various pathogens such as Mycobacterium tuberculosis (Mtb) — the TB-causing bacterium.
In the study, the risk was seen in young mice, not in older ones.
It was due to the production of a protein IFN-a — involved in innate immune response against viral infection — in the lungs by a subset of immune cells that express molecules called CD11b and Ly6G, explained researchers, led by Deepak Tripathi of the University of Texas.
For the study, published in the journal PLOS Pathogens, young and old mice were fed alcohol or control diets for one month and then infected with MtbH37Rv.
The analysis showed that 80 per cent of Mtb-infected alcohol-fed young mice died within 6 months, while the death rate was 25 per cent in Mtb-infected alcohol-fed old mice.
Further, among patients with latent tuberculosis infection, peripheral blood mononuclear cells from young alcoholic individuals produced significantly higher amounts of IFN-a than those from young non-alcoholic, old alcoholic, and old non-alcoholic individuals.
This suggests that young alcoholic individuals with latent tuberculosis infection have a higher risk of developing active tuberculosis infection.
According to the researchers, the study could facilitate the development of therapies for alcoholic individuals with latent and active Mtb infections.