HIV Infection and the Gut: Scarred for Life?

Over the past decade, the gut-associated lymphocytes have been shown to play a critical role in the early pathogenesis of HIV infection. Because of constant exposure to foreign antigens, the gut contains an abundance of activated effector memory CD4+ T cells that express CCR5 and are highly susceptible to HIV infection [1]. Primary HIV infections and simian immunodeficiency virus (SIV) infections lead to rapid and profound depletion of these cells [2-4], which is more pronounced than the depletion in peripheral blood or other lymphoid tissue and persists throughout the course of untreated infection. The administration of antiretroviral therapy during chronic infection is highly effective in increasing the number of CD4+ T cells and decreasing the proportion of activated T cells in peripheral blood. However, significant delay in CD4+ T cell restoration maybe seen in the gut, particularly in the lamina propria [5] . Despite the slow or incomplete resolution of the profound abnormalities seen in the gut mucosa of HIV-infected patients, a clear connection to clinical outcome in