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Medical Lake, WA, United States

Gil S.,University of Washington | Farnand A.W.,University of Washington | Altemeier W.A.,University of Washington | Gill S.E.,Lawson Health Research Institute | And 5 more authors.
Respiratory Research | Year: 2012

Background: Exposure to mechanical ventilation enhances lung injury in response to various stimuli, such as bacterial endotoxin (LPS). The Fas/FasL system is a receptor ligand system that has dual pro-apoptotic and pro-inflammatory functions and has been implicated in the pathogenesis of lung injury. In this study we test the hypothesis that a functioning Fas/FasL system is required for the development of lung injury in mechanically ventilated mice.Methods: C57BL/6 (B6) and Fas-deficient lpr mice were exposed to either intra-tracheal PBS followed by spontaneous breathing or intra-tracheal LPS followed by four hours mechanical ventilation with tidal volumes of 10 mL/kg, respiratory rate of 150 breaths per minute, inspired oxygen 0.21 and positive end expiratory pressure (PEEP) of 3 cm of water.Results: Compared with the B6 mice, the lpr mice showed attenuation of the neutrophilic response as measured by decreased numbers of BAL neutrophils and lung myeloperoxidase activity. Interestingly, the B6 and lpr mice had similar concentrations of pro-inflammatory cytokines, including CXCL1 (KC), and similar measurements of permeability and apoptosis. However, the B6 mice showed greater deposition of anti-KC:KC immune complexes in the lungs, as compared with the lpr mice.Conclusions: We conclude that a functioning Fas/FasL system is required for full neutrophilic response to LPS in mechanically ventilated mice. © 2012 Gil et al.; licensee BioMed Central Ltd. Source

Manickam N.,University of Texas Health Science Center at San Antonio | Patel M.,University of Texas Health Science Center at San Antonio | Griendling K.K.,Emory University | Gorin Y.,University of Texas Health Science Center at San Antonio | And 2 more authors.
American Journal of Physiology - Renal Physiology | Year: 2014

The small G proteins Rac1 and RhoA regulate actin cytoskeleton, cell shape, adhesion, migration, and proliferation. Recent studies in our laboratory have shown that NADPH oxidase Nox4-derived ROS are involved in transforming growth factor (TGF)-β1-induced rat kidney myofibroblast differentiation assessed by the acquisition of an α-smooth muscle actin (α-SMA) phenotype and expression of an alternatively spliced fibronectin variant (Fn-EIIIA). Rac1 and RhoA are essential in signaling by some Nox homologs, but their role as effectors of Nox4 in kidney myofibroblast differentiation is not known. In the present study, we explored a link among Rac1 and RhoA and Nox4-dependent ROS generation in TGF-β1-induced kidney myofibroblast activation. TGF-β1 stimulated an increase in Nox4 protein expression, NADPH oxidase activity, and abundant α-SMA and Fn-EIIIA expression. RhoA but not Rac1 was involved in TGF-β1 induction of Nox4 signaling of kidney myofibroblast activation. TGF-β1 stimulated active RhoA-GTP and increased Rho kinase (ROCK). Inhibition of RhoA with small interfering RNA and ROCK using Y-27632 significantly reduced TGF-β1-induced stimulation of Nox4 protein, NADPH oxidase activity, and α-SMA and Fn-EIIIA expression. Treatment with diphenyleneiodonium, an inhibitor of NADPH oxidase, did not decrease RhoA activation but inhibited TGF-β1-induced α-SMA and Fn-EIIIA expression, indicating that RhoA is upstream of ROS generation. RhoA/ROCK also regulated polymerase (DNA-directed) δ-interacting protein 2 (Poldip2), a newly discovered Nox4 enhancer protein. Collectively, these data indicate that RhoA/ROCK is upstream of Poldip2-dependent Nox4 regulation and ROS production and induces redox signaling of kidney myofibroblast activation and may broader implications in the pathophysiology of renal fibrosis. © 2014 the American Physiological Society. Source

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