Induction of human β-defensin-2 in airway epithelial cells by Streptococcus pneumoniae: involvement of IP3-dependent intracellular calcium release and NF-κB

Human beta-definsin-2 (hBD-2) is mainly induced by bacterial factors and pro-inflammation mediators in epithelial cells. As the major cause of community-acquired pneumonia, whether Streptococcus pneumoniae (S. pneumoniae) stimulation induces hBD-2 expression in airway epithelial cells is elusive. In this study, we found that S. pneumoniae stimulation induced hBD-2 expression in a time- and concentration-dependent manner in primary human airway epithelial cells. To further reveal the mechanism of S. pneumoniae inducing hBD-2, we found that S. pneumoniae stimulation activated NF-kappa B signaling pathway. Specific NF-kappa B inhibitor, PDTC, could reverse the induction of hBD-2 by S. pneumoniae. We also found that cellular inner Ca2+ signaling is involved in the S. pneumoniae-induced hBD-2. Taken together, our findings indicated that S. pneumoniae can stimulate the expression of hBD-2 in airway epithelial cells and NF-kappa B and inositol triphosphate-dependent intracellular calcium release is involved in this induction.