Systemic And Mucosal Mobilization Of Granulocyte Subsets During Lentiviral Infection

Granulocytes mediate broad immunoprotection through phagocytosis, extracellular traps, release of cytotoxic granules, antibody effector functions and recruitment of other immune cells against pathogens. However, descriptions of granulocytes in HIV infection and mucosal tissues are limited. Our goal was to characterize granulocyte subsets in systemic, mucosal and lymphoid tissues during lentiviral infection using the rhesus macaque (RM) model. Mononuclear cells from jejunum, colon, cervix, vagina, lymph nodes, spleen, liver and whole blood from experimentally naive and chronically SHIVsf162p3-infected RM were analysed by microscopy and polychromatic flow cytometry. Granulocytes were identified using phenotypes designed specifically for RM: eosinophils-CD45(+) CD66(+) CD49d(+); neutrophils-CD45(+) CD66(+) CD14(+); and basophils-CD45(+) CD123(+) FcR epsilon(+). Nuclear visualization with DAPI staining and surface marker images by ImageStream (cytometry/microscopy) further confirmed granulocytic phenotypes. Flow cytometric data showed that all RM granulocytes expressed CD32 (FcR gamma II) but did not express CD16 (FcR gamma III). Additionally, constitutive expression of CD64 (FcR gamma I) on neutrophils and FcR epsilon on basophils indicates the differential expression of Fc receptors on granulocyte subsets. Granulocytic subsets in naive whole blood ranged from 25 center dot 4% to 81 center dot 5% neutrophils, 0 center dot 59% to 13 center dot 3% eosinophils and 0 center dot 059% to 1 center dot 8% basophils. Interestingly, elevated frequencies of circulating neutrophils, colorectal neutrophils and colorectal eosinophils were all observed in chronic lentiviral disease. Conversely, circulating basophils, jejunal eosinophils, vaginal neutrophils and vaginal eosinophils of SHIVsf162p3-infected RM declined in frequency. Overall, our data suggest modulation of granulocytes in chronic lentiviral infection, most notably in the gastrointestinal mucosae where a significant inflammation and disruption occurs in lentivirus-induced disease. Furthermore, granulocytes may migrate to inflamed tissues during infection and could serve as targets of immunotherapeutic intervention.