Deletion of src family kinase Lyn aggravates endotoxin-induced lung inflammation

Overwhelming acute inflammation often leads to tissue damage during endotoxemia. In the present study, we investigated the role of Lyn, a member of the Src family tyrosine kinases, in modulating inlammatory responses in a murine model of endotoxemia. We examined lung inflammatory signaling in Lyn knockout (Lyn^-/-) mice and wild-type littermates (Lyn^+/+) during endotoxemia. Our data indicate that Lyn deletion aggravates endotoxin-induced pulmonary inlammation and proin-lammatory signaling. We found increased activation of proinlam-matory transcription factor NF-ΚB in the lung tissues of Lyn^-/- mice after endotoxin challenge. Furthermore, during endotoxemia, the lung tissues of Lyn^-/- mice showed increased inflammasome activation indicated by augmented caspase-1 and IL-1ß cleavage and activation. The aggravated lung inflammatory signaling in Lyn^-/- mice was associated with increased production of proinlammatory mediators and elevated matrix metallopeptidase 9 and reduced VE-cadherin levels. Our results suggest that Lyn kinase modulates inhibitory signaling to suppress endotoxin-induced lung inlammation.