The Impact of Vitamin A Deficiency on Tuberculosis Progression

Among a cohort of individuals living with human immunodeficiency virus, baseline vitamin A deficiency was associated with increased risk of future progression to tuberculosis (TB). Vitamin A-deficient guinea pigs also experienced higher bacillary loads and had distinct histopathological responses to TB exposure. Background Although previous studies have shown that vitamin A deficiency is associated with incident tuberculosis (TB) disease, the direction of the association has not been established. We investigated the impact of vitamin A deficiency on TB disease progression. Methods We conducted a longitudinal cohort study nested within a randomized clinical trial among HIV-infected patients in Haiti. We compared serial vitamin A levels in individuals who developed TB disease to controls matched on age, gender, follow-up time, and time to antiretroviral therapy initiation. We also evaluated histopathology, bacterial load, and immune outcomes in TB infection in a guinea pig model of dietary vitamin A deficiency. Results Among 773 participants, 96 developed incident TB during follow-up, 62.5% (60) of whom had stored serum samples obtained 90-365 days before TB diagnosis. In age- and sex- adjusted and multivariate analyses, respectively, incident TB cases were 3.99 times (95% confidence interval [CI], 2.41 to 6.60) and 3.59 times (95% CI, 2.05 to 6.29) more likely to have been vitamin A deficient than matched controls. Vitamin A-deficient guinea pigs manifested more extensive pulmonary pathology, atypical granuloma morphology, and increased bacterial growth after experimental TB infection. Reintroduction of dietary vitamin A to deficient guinea pigs after established TB disease successfully abrogated severe disease manifestations and altered cellular immune profiles. Conclusions Human and animal studies support the role of baseline vitamin A deficiency as a determinant of future TB disease progression.

Automated summary

This study demonstrates an association between baseline vitamin A deficiency and increased risk of tuberculosis progression among individuals living with HIV. Guinea pigs deficient in vitamin A also exhibited more severe pathological responses and increased bacterial growth after TB infection.