Project description:Monocytes have been categorized in three main subpopulations based on CD14 and CD16 surface expression. Classical monocytes are the most abundant subset in the blood. They express a CD14+CD16-CCR2+ phenotype, which confers on them the ability to migrate to inflammatory sites by quickly responding to CCL2 signaling. Here we identified and characterized the surge and expansion of a novel monocyte subset during SIV and HIV infection. They were undistinguishable from classical monocytes regarding CD14 and CD16 expression, but did not express surface CCR2. Transcriptome analysis of sorted cells confirmed that they represent a distinct subpopulation that expresses lower levels of inflammatory cytokines and activation markers than their CCR2+ counterparts. They exhibited impaired phagocytosis and deficient chemotaxis in response to CCL2 and CCL7, besides being refractory to SIV infection. We named these cells atypical CCR2- classical (ACC) monocytes, and believe they play an important role in AIDS pathogenesis, possibly reflecting an anti-inflammatory response against the extreme immune activation observed during SIV and HIV infection. Antiretroviral therapy caused this population to decline in both macaque and human subjects, suggesting that this atypical phenotype may be induced by viral replication. Expression profiling by NanoString nCounter gene expression system. Classical monocytes (CD14++CD16-) from six SIV-infected macaques (day 14 post inoculation) were sorted in two groups according to CCR2 expression.
Project description:Monocytes have been categorized in three main subpopulations based on CD14 and CD16 surface expression. Classical monocytes are the most abundant subset in the blood. They express a CD14+CD16-CCR2+ phenotype, which confers on them the ability to migrate to inflammatory sites by quickly responding to CCL2 signaling. Here we identified and characterized the surge and expansion of a novel monocyte subset during SIV and HIV infection. They were undistinguishable from classical monocytes regarding CD14 and CD16 expression, but did not express surface CCR2. Transcriptome analysis of sorted cells confirmed that they represent a distinct subpopulation that expresses lower levels of inflammatory cytokines and activation markers than their CCR2+ counterparts. They exhibited impaired phagocytosis and deficient chemotaxis in response to CCL2 and CCL7, besides being refractory to SIV infection. We named these cells atypical CCR2- classical (ACC) monocytes, and believe they play an important role in AIDS pathogenesis, possibly reflecting an anti-inflammatory response against the extreme immune activation observed during SIV and HIV infection. Antiretroviral therapy caused this population to decline in both macaque and human subjects, suggesting that this atypical phenotype may be induced by viral replication. Expression profiling by NanoString nCounter gene expression system.