Osteopontin induced inhibition of dendritic cell polarization towards pDC cells is not exclusively mediated by NKT cells (147.28)

Abstract

Abstract Pediatric post-RSV infection associated bronchial asthma is known to be mediated via an enhanced pulmonary Th2 response. However, adult RSV infection is not known to be associated with this pathology. Further, osteopontin and NKT cell have been reported to be involved with induction of Th1 and Th2 type host-immune responses, respectively. The effect of NKT cells on naïve T helper cells is suggested to be a result of NKT cells’ subsequent modulation of naïve dendritic cells (DCs) towards plasmacytoid DCs (pDCs). So, in our present studies, using an NKT cell KO (CD1d-/-) mouse model, we have studied the role of osteopontin and NKT cells in modulating the polarization of DCs towards pDC in RSV-infected neonatal lungs. Flowcytometry analysis determined that there was an enhanced NKT cell (CD19-CD4+CD1d+) response in the RSV-infected neonatal lungs compared to that in the infected adult lungs. There was a decrease in the NKT cell response to RSV infection in the neonatal lungs upon concomitant administration of exogenous osteopontin as compared to those without osteopontin. Furthermore, in the absence of NKT cells (CD1d-/-), the administration of exogenous osteopontin induced inhibition of DC polarization towards pDC. Thus, differential pDC responses to RSV infection in neonates with exogenous osteopontin administration, even in the absence of NKT cells, warrants investigation into involvement of other factors in the development of RSV-induced bronchial asthma in later life.