Project description:Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is an inflammatory process of the lungs characterized by increased permeability of the alveolar-capillary membrane with subsequent interstitial/alveolar edema and diffuse alveolar damage. ALI/ARDS can be the results of either direct or indirect lung injury, with pneumonia being the most common direct pulmonary insult and sepsis the most common extra-pulmonary cause. In this study, we employed the murine lipopolysaccharide (LPS)-induced direct and indirect lung injury model to explore the pathogenic mechanisms of pulmonary and extra-pulmonary ARDS, using an unbiased, discovery and quantitative proteomic approach. A total of 1,017 proteins were both identified and quantified in bronchoalveolar lavage fluid (BALF) from control, intratracheal LPS (I.T. LPS, 0.1 mg/kg) and intraperitoneal LPS (I.P. LPS, 5 mg/kg) treated mice. The two LPS groups shared 13 up-regulated and 22 down-regulated proteins compared to the control group. Among them, molecules related to bronchial and type II alveolar epithelial cell functions including cell adhesion molecule 1 and surfactant protein B were reduced, whereas lactotransferrin and resistin like alpha involved in lung innate immunity were upregulated in both LPS groups. Proteomic profiling also identified significant differences in BALF proteins between I.T. and I.P. LPS groups. Ingenuity pathway analysis revealed that acute-phase response signaling was activated by both I.T. and I.P. LPS, however, the magnitude of activation is much greater in I.T. LPS group compared to I.P. LPS group. Intriguingly, two canonical signaling pathways, liver X receptor/retinoid X receptor activation and the production of nitric oxide and reactive oxygen species in macrophages, were activated by I.T. LPS but suppressed by I.P. LPS. In addition, CXCL15 (also known as lungkine) was also up-regulated by I.T LPS but down-regulated by I.P. LPS. In conclusion, our quantitative discovery-based proteomic approach identified commonalities as well as significant differences in BALF protein expression profiles in LPS-induced direct and indirect lung injury, and importantly, LPS-induced indirect lung injury results in suppression of select components of lung innate immunity, which could contribute to the so-called “immunoparalysis” in sepsis patients.

Project description:Acute lung injury (ALI), a major cause of acute respiratory failure with high morbidity and mortality, isare characterized by significant pulmonary inflammation and both alveolar and vascular barriers dysfunction. In Pprior studies have highlighted the role of nonmuscle myosin light chain kinase (nmMLCK) as an essential element of inflammatory response with MYLK polymorphisms associated withwhich alters ALI susceptibility. In the present study we sought to further define nmMLCK in acute inflammatory syndromes and examined We examined nmMLCK as a molecular target involved in increase of lung epithelial and endothelial barrier permeability. We utilized in two muirine models of inflammatory lung injury: intratracheal administration of endotoxin/lipopolysaccharide (LPS, 2.5 mg/kg) and VILI (ventilator-induced lung injury, tidal volume 40ml/kg). Two complementary strategies were used to reduce nmMLCK activity or expression. We found that membrane permeant oligopeptide, PIK, inhibited MLC kinase activity in vitro in aand displayed dose-dependent mannerinhibition of MLC kinase activity.. Intravenous delivery of PIK significantly attenuated LPS-induced lung inflammation reflected by decreasing accumulation of bronchoalveolar lavage (BAL) albumin (~ 50% reduction) as well as reduction in BAL cells, tissue MPO activity and tissue albumin in lung homogenates. A second regulatory approach explored targeting murine nmMLCK by administration of siRNA (5mg/kg) 3 days prior to LPS challenge. siRNA decreased of nmMLCK expression in lungs (~ 70% reduction) and resulted in significant attenuation LPS-induced lung inflammation (~ 40% reduction) as reflected by decreased BAL protein level and BAL cells. For targeting pulmonary vessels nmMLCK we used ACE antibody-conjugated liposomes with nmMLCK siRNA in murine ventilator-induced lung injury (VILI) model. Protein silencing of nmMLCK was evident by immunohistochemical analysis with a decrease in relative intensity of fluorescence in lung vessels compared with control animals. Furthermore, the inhibition of nmMLCK expression by siRNA in vessels significantly attenuated VILI lung injury as reflected by decreased BAL protein level (40% reduction). Finally, MLCK knockout mice were significantly protected (reduced BAL protein and albumin) when exposed to a model of severe VILI (4h, 40ml/kg tidal volume). Conclusion: the MLCK gene KO and chemical biology results indicate that the targeting of nmMLCK in vivo attenuate the severity of LPS-induced or VILI acute lung injury. We used microarrays to detail the global programme of gene expression induced by VILI in Wild type and nmMLCK-/- mouse. Experiment Overall Design: four group (n=3) of animals were treated by SB (Spontaneouse breathing) or VILI (4 hours, 30 ml/kg tidal volume) in Wild type or nmMLCK-/- animals;

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