CD4 Tcells are rapidly depleted from tuberculosis granulomas following acute SIV co-infection.

Abstract

HIV/Mycobacterium tuberculosis (Mtb) co-infected individuals have an increased risk of tuberculosis prior to loss of peripheral CD4 Tcells, raising the possibility that HIV co-infection leads to CD4 Tcell depletion in lung tissue before it is evident in blood. Here, we use rhesus macaques to study the early effects of simian immunodeficiency virus (SIV) co-infection on pulmonary granulomas. Two weeks after SIV inoculation of Mtb-infected macaques, Mtb-specific CD4 Tcells are dramatically depleted from granulomas, before CD4 Tcell loss in blood, airways, and lymph nodes, or increases in bacterial loads or radiographic evidence of disease. Spatially, CD4 Tcells are preferentially depleted from the granuloma core and cuff relative to B cell-rich regions. Moreover, live imaging of granuloma explants show that intralesional CD4 Tcell motility is reduced after SIV co-infection. Thus, granuloma CD4 Tcells may be decimated before many co-infected individuals experience the first symptoms of acute HIV infection.