Macrophages Are Phenotypically and Functionally Diverse across Tissues in Simian Immunodeficiency Virus-Infected and...

Macrophages regulate tissue immunity, orchestrating the initiation and resolution of antimicrobial immune responses and repair of damaged tissue architecture. Their dysfunction can, thus, manifest in either pro- and anti-inflammatory responses. Indeed, despite the importance of macrophage function in health and disease, the role of tissue-resident macrophages in human immunodeficiency virus (HIV) disease progression remains incompletely defined. Here, we use flow cytometry to assess the phenotypes and functions of macrophages isolated from the spleens, axillary lymph nodes, colons, jejuna, and livers of healthy and chronically simian immunodeficiency virus (SIV)-infected Asian macaques, the prominent nonhuman primate model for HIV infection. Our data demonstrate that macrophages from healthy animals exhibit considerable phenotypic and functional heterogeneity across tissues and across a variety of stimuli. Further, our analysis reveals changes in the lipopolysaccharide (LPS) responsiveness of macrophages isolated from SIV-infected animals. We anticipate that our findings will inform future research into macrophage-directed immunity across a variety of primate diseases.

These findings highlight the functional and phenotypic heterogeneity of tissue macrophages in different anatomic sites and as a result of SIV infection. We believe that our data will lead to novel therapeutic interventions aimed at altering the proinflammatory capacity of tissue macrophages in progressively HIV-infected individuals.