The mechanisms responsible for increased cardiovascular risk associated with HIV-1 infection are incompletely defined. Using flow cytometry, in the present study, we examined activation phenotypes of monocyte subpopulations in patients with HIV-1 infection or acute coronary syndrome to find common cellular profiles. Nonclassic (CD14(+)CD16(++)) and intermediate (CD14(++)CD16(+)) monocytes are proportionally increased and express high levels of tissue factor and CD62P in HIV-1 infection. These proportions are related to viremia, T-cell activation, and plasma levels of IL-6. In vitro exposure of whole blood samples from uninfected control donors to lipopolysaccharide increased surface tissue factor expression on all monocyte subsets, but exposure to HIV-1 resulted in activation only of nonclassic monocytes. Remarkably, the profile of monocyte activation in uncontrolled HIV-1 disease mirrors that of acute coronary syndrome in uninfected persons. Therefore, drivers of immune activation and inflammation in HIV-1 disease may alter monocyte subpopulations and activation phenotype, contributing to a pro-atherothrombotic state that may drive cardiovascular risk in HIV-1 infection.
Interactions of AMPs with plasma membranes of primary human immune cells are poorly characterized. Analysis of PI exclusion as a measure of membrane integrity indicated that hBD-3 caused membrane perturbations in monocytes but not T or B cells at concentrations typically used to kill bacteria or to induce activation of APCs. Bleb-like structures were observed in monocytes exposed to hBD-3. These cells also increased surface expression of LAMP1, a membrane repair marker after exposure to hBD-3. Furthermore, cell death was enhanced by adding an inhibitor of membrane repair. Removal of cholesterol from membranes resulted in greater susceptibility of cells to hBD-3, but cholesterol content was not different between the cell types, as assessed by filipin staining. Freshly isolated monocytes expressed higher levels of the negatively charged phospholipid, PS, on their outer leaflet compared with B or T cells. Preincubation of monocytes with molecules that bind PS protected these cells from hBD-3-induced membrane damage, suggesting that outer-membrane PS expression can at least partially explain monocyte susceptibility to hBD-3. The potential for membrane disruption caused by AMPs should be evaluated in various cell types when considering these molecules for therapeutic applications in humans.
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