CDHR4 and acute respiratory distress syndrome: Among the barrier function genes screened by qRT-PCR, significantly increased expression of CLDN3 (threefold), CDHR3 (twofold), and CDHR4 (sevenfold) was detected in wood smoke exposed bro-ALI whereas only PCDHGA5 (sevenfold) was significantly increased in case of wood smoke exposed bro-ALI-CB compared to the corresponding sham controls (Additional file 1: Table ST8).