ObjectiveTo investagte the effects of single immunoglobin IL-1 receptor related protein (SIGIRR) on inflammation induced by cigarette smoke extract (CSE) in A549 cells derived from mouse alveolar epithelial cells. MethodsA549 cells were divided into a control group and an over-expressed SIGIRR group. Eukaryotic expression vectors pcDNA3.1(+) constructed with SIGIRR cDNA were transiently transfected into A549 cells, in which SIGIRR was forced to be over-expressed. The expression level of SIGIRR after transfection was detected with Western blot and RT-PCR method. After stimulated by CSE in both groups, the protein level of IL-6 was detected by ELISA, the transcriptional activity of cyclooxygenase-2(COX-2) was detected by dual-luciferase reporter assay system, and the release of reactive oxygen species (ROS) was measured by chemiluminescence method. ResultsThe expression level of SIGIRR increased significantly in A549 cells transfected with SIGIRR vectors. The COX-2 expression and the levels of ROS and IL-6 were significantly increased in the control group after CSE stimulation. Nevertheless, in the over-expressed SIGIRR group, the COX-2 expression and the release of ROS was reduced while the protein level of IL-6 was down-regulated compared with the control group(P < 0.05). ConclusionsUp-regulated SIGIRR expression can suppress the levels of ROS, COX-2 and IL-6 in A549 cells stimulated by CSE. It suggests that SIGIRR can inhibit airway inflammation caused by smoking.