TB provides HIV's little helpers

Cellular Microbiology It is well known that tuberculosis (TB) can exacerbate HIV pathology, and exactly how it does that involves a variety of factors. Souriant et al. studied the interactions between the two pathogens in cell culture. They found that macrophages induced by TB infection were particularly susceptible to HIV infection in vitro. One class of TB-induced macrophages called M(IL-10) cells were more prevalent during coinfection with HIV [or simian immunodeficiency virus (SIV) in a nonhuman primate model]. It appears that the TB infection created an environment in which macrophages produced so-called tunneling nanotubes (TNTs). These cellular protrusions connect cells, allowing cell-to-cell transfer of viruses. The TNTs promoted viral spread without directly affecting viral entry, viral activation, or viral restriction factors. Thus, TB appears to promote a microenvironment within patient tissues that facilitates HIV production. Cell Rep. 26 , 3586 (2019).