Establishment of a porcine bronchial epithelial cell line and its application to study innate immunity in the respiratory epithelium

Abstract

In vitro culture models that precisely mirror the porcine respiratory epitheliumare needed to gain insight into how pathogens and host interact. In this study, anew porcine bronchial epithelial cell line, designated as PBE cells, wasestablished from the respiratory tract of a neonatal pig. PBE cells assumed acobblestone-epithelial like morphology with close contacts between the cellswhen they reached confluence. The PBE cell line was characterized in terms ofits expression of pattern recognition receptors (PRRs) and its ability to respond tothe activation of the Toll-like receptor 3 (TLR3) and TLR4 signaling pathways,which are key PRRs involved in the defense of the respiratory epithelium againstpathogens. PBE cells stimulated with poly(I:C) were able to up-regulate theexpression of IFN-b, IFN-l1 (IL-29), IFN-l3 (IL-28B), the antiviral factors Mx1,OAS1, and PKR, as well as the viral PRRs RIG-1 and MDA5. The expression kineticsstudies of immune factors in PBE cells allow us to speculate that this cell line canbe a useful in vitro tool to investigate treatments that help to potentiate antiviralimmunity in the respiratory epithelium of the porcine host. In addition, poly(I:C)and LPS treatments increased the expression of the inflammatory cytokines TNFa, IL-6, IL-8, and MCP-1/CCL2 and differentially modulated the expression ofnegative regulators of the TLR signaling pathways. Then, PBE cells may also allowthe evaluation of treatments that can regulate TLR3- and TLR4-mediatedinflammatory injury in the porcine airway, thereby protecting the host againstharmful overresponses.