Osteopontin receptor expression on immune effector cells in neonatal RSV infection (P3232)

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Abstract Respiratory Syncitial Virus (RSV)-induced bronchiolitis-pneumonia during early infancy predisposes asthma in later life. Augmented Th2 response and skewed polarization of Dendritic cells (DC) towards plasmacytoid DC (pDC) are associated. In addition, Osteopontin (OPN) serves as an immunomodulator, which is relatively deficient in RSV- infected neonatal lungs. Exogenous OPN inhibits skewed pDC polarization in RSV- infected neonatal mice. In the present study, we examined the expression of OPN receptors (CD44 and CD51/61) by flowcytometry on pDC, myeloid DC (mDC), T and B cells in response to RSV infection in the presence and absence of NKT cells using wild type (WT) and NKT cell KO (NKT-/-) mouse models. Neonates and adults are shown to exhibit NKT and NK dominant responses, respectively, in RSV infections. Expression of CD44 and CD51/61 decreased on mDC, pDC, T and B cells in RSV infected WT pups compared to the uninfected pups particularly early on infection (day 2 and 4 post-infection). On the other hand, expression OPN receptors on DC, T and B cells were increased in the RSV-infected NKT-/- pups compared to the infected WT and uninfected NKT-/- pups. This augmented expression was abolished by day 10 post-infection. Increased expression of OPN receptors in absence of NKT cells signifies their inhibitory role. Further studies examining the roles of NKT cells in OPN treatment would help understand the underlying mechanisms for developing new therapeutic strategies.