Sulphur dioxide suppresses inflammatory response by sulphenylating NF-κB p65 at Cys in a rat model of acute lung injury.

The present study was designed to investigate whether endogenous sulphur dioxide (SO) controlled pulmonary inflammation in a rat model of oleic acid (OA)-induced acute lung injury (ALI). In this model, adenovirus expressing aspartate aminotransferase (AAT) 1 was delivered to the lungs, and the levels of SO and proinflammatory cytokines in rat lung tissues were measured. In the human alveolar epithelial cell line A549, the nuclear translocation and DNA binding activities of wild-type (wt) and C38S (cysteine-to-serine mutation at p65 Cys) NF-κB p65 were detected. GFP-tagged C38S p65 was purified from HEK 293 cells and the sulphenylation of NF-κB p65 was studied. OA caused a reduction in SO/AAT pathway activity but increased pulmonary inflammation and ALI. However, either the presence of SO donor, a combination of NaSO and NaHSO, or AAT1 overexpression successfully blocked OA-induced pulmonary NF-κB p65 phosphorylation and consequent inflammation and ALI. Either treatment with an SO donor or overexpression of AAT1 down-regulated OA-induced p65 activity, but AAT1 knockdown in alveolar epithelial cells mimicked OA-induced p65 phosphorylation and inflammation Mechanistically, OA promoted NF-κB nuclear translocation, DNA binding activity, recruitment to the intercellular cell adhesion molecule (ICAM)-1 promoter, and consequent inflammation in epithelial cells; these activities were reduced in the presence of an SO donor. Furthermore, SO induced sulphenylation of p65, which was blocked by the C38S mutation on p65 in epithelial cells. Hence, down-regulation of SO/AAT is involved in pulmonary inflammation during ALI. Furthermore, SO suppressed inflammation by sulphenylating NF-κB p65 at Cys.