Inhibition of the Src and Jak Kinases Protects against Lipopolysaccharide-induced Acute Lung Injury

Abstract

The cascade of cellular and molecular pathways mediating acute lung injury is complex and incompletely defined. Although the Src and Jak family of kinases is upregulated in LPS-induced murine lung injury, their role in the development of lung injury is unknown. Here we report that systemic inhibition of these kinases using specific small molecule inhibitors (PP2, SU6656, tyrphostin A1) significantly attenuated LPS-induced lung injury, as determined by histologic and capillary permeability assays. These inhibitors blocked LPS-dependent cytokine and chemokine production in the lung and in the serum. In contrast, lung-targeted inhibition of these kinases in the airway epithelium via adenoviral-mediated gene transfer of dominant negative Src or of suppressor of cytokine signaling (SOCS-1) disrupted lung cytokine production but had no effect on systemic cytokine production or lung vascular permeability. Mice were significantly protected from lethal LPS challenge by the small molecule inhibitors of Jak and Src kinase. Importantly, this protection was still evident even when the inhibitors were administered 6 hours after LPS challenge. Taken together, these observations suggest that Jak and Src kinases participate in acute lung injury and verify the potential of this class of selective tyrosine kinase inhibitors to serve as novel therapeutic agents for this disease.

Mechanical ventilation augments bleomycin-induced epithelial–mesenchymal transition through the Src pathway

“…34 Our results revealed that mechanical ventilation induced the phosphorylation of Src both in lung tissue and isolated myofibroblasts, which can be suppressed by Src knockout or pharmacologic inhibition with PP2, a selective Src kinase inhibitor remaining effective up to 6 h after ALI. 14,20,22 However, PP2 is a hydrophobic chemical and can only be dissolved in the toxic organic solvent dimethyl sulfoxide. The recent development of nanoscale combinations of self-assembling peptides (EAK16-II) and amino acids can improve the biocompatibility of previous PP2 formulation and advance its potential clinical use.…”

“…Despite its extensive use as a Srcselective inhibitor, recent studies have demonstrated that PP2 also reduced the activation of serine/threonine kinase/protein kinase B, beta-catenin, Jak kinase and phosphoinositide 3-OH kinase. 13,22 Further experiments are necessary to explore potential regulators of VILI.…”

“…5 PP2 is a Src inhibitor (2 mg/kg; Calbiochem, La Jolla, CA, USA), and was given intraperitoneally 30 min before mechanical ventilation, based on previous in vivo study that showed 2 mg/kg PP2 inhibited Src activity and lung injury. 22 …”

“…14,19,20 Src inhibitors that are used in vivo may suppress inflammatory responses, involving neutrophils, monocytes, macrophages, endothelial and epithelial cells. 21,22 Given the absence of a proven effective treatment for acute lung injury (ALI) and EMT, Src inhibition may provide an attractive target in the devastating process of patients with ARDS. 14,23 In this high-V T ventilation-induced lung injury model of mice pretreated with bleomycin, we compared the effects among various V T of mechanical ventilation, the correlation of EMT to fibroblast accumulation and epithelial apoptosis, and the production of PAI-1 and TGF-b1 using pharmacological inhibitors PP2 and Src-deficient mice.…”

TLR4 Signaling Is Coupled to SRC Family Kinase Activation, Tyrosine Phosphorylation of Zonula Adherens Proteins, and Opening of the Paracellular Pathway in Human Lung Microvascular Endothelia

“…The kinetics of LPS-induced SFK activation in HMVEC-Ls parallel those described in LPStreated macrophages (30) and TNF␣-treated ECs (10). SFKselective inhibitors (PP2 and SU6656) attenuate both LPS-induced lung injury and increases in pulmonary vascular permeability in vivo (79). Other agonists, such as VEGF and TNF␣, also increase endothelial permeability through SFK activation (10,80).…”