Major and Minor Group Human Rhinovirus Response in Human Macrophages

Major- and minor-group rhinoviruses enter their host by binding to the cell surface molecules ICAM-1 and LDL-R, respectively, which are present on both macrophages and epithelial cells. Although epithelial cells are the primary site of productive HRV infection, previous studies have implicated macrophages in establishing the cytokine dysregulation that occurs during rhinovirus-induced asthma exacerbations. Even though major- and minor-group rhinoviruses are nearly genetically identical, these viruses do not replicate with equal success in monocyte-lineage cell lines. In human primary macrophages, differential mitochondrial activity and signaling pathway activation was observed between major- and minor-group rhinovirus upon initial HRV binding, indicating discordant receptor-dependent response to these rhinovirus types. As well, variances in phosphorylation of kinases (p38, JNK, ERK5) and transcription factors (ATF-2, CREB, CEBP-alpha) were observed between the major- and minor- group HRV treatments. The difference between major- and minor- group HRV activation of signaling pathways was confirmed through RNA-sequencing and observation of differential production of the asthma-relevant cytokines CCL20, CCL2, and IL-10. This is the first report of genetically similar viruses eliciting dissimilar cytokine release, transcription factor phosphorylation, and MAPK activation from macrophages. These results suggest that receptor dependence plays a role in establishing the inflammatory microenvironment initiated in part by monocytic-lineage cells in the human airway upon exposure to rhinovirus. RNA sequencing of monocyte-derived macrophages after mock infection or infection by HRV16 or HRV1A