TNF-? mediated increase of HIF-1? inhibits VASP expression, which reduces alveolar-capillary barrier function during acute lung injury (ALI).

ABSTRACT: Acute lung injury (ALI) is an inflammatory disorder associated with reduced alveolar-capillary barrier function and increased pulmonary vascular permeability. Vasodilator-stimulated phosphoprotein (VASP) is widely associated with all types of modulations of cytoskeleton rearrangement-dependent cellular morphology and function, such as adhesion, shrinkage, and permeability. The present studies were conducted to investigate the effects and mechanisms by which tumor necrosis factor-alpha (TNF-?) increases the tight junction permeability in lung tissue associated with acute lung inflammation. After incubating A549 cells for 24 hours with different concentrations (0-100 ng/mL) of TNF-?, 0.1 to 8 ng/mL TNF-? exhibited no significant effect on cell viability compared with the 0 ng/mL TNF-? group (control group). However, 10 ng/mL and 100 ng/mL TNF-? dramatically inhibited the viability of A549 cells compared with the control group (*p<0.05). Monolayer cell permeability assay results indicated that A549 cells incubated with 10 ng/mL TNF-? for 24 hours displayed significantly increased cell permeability (*p<0.05). Moreover, the inhibition of VASP expression increased the cell permeability (*p<0.05). Pretreating A549 cells with cobalt chloride (to mimic a hypoxia environment) increased protein expression level of hypoxia inducible factor-1? (HIF-1?) (*p<0.05), whereas protein expression level of VASP decreased significantly (*p<0.05). In LPS-induced ALI mice, the concentrations of TNF-? in lung tissues and serum significantly increased at one hour, and the value reached a peak at four hours. Moreover, the Evans Blue absorption value of the mouse lung tissues reached a peak at four hours. The HIF-1? protein expression level in mouse lung tissues increased significantly at four hours and eight hours (**p<0.001), whereas the VASP protein expression level decreased significantly (**p<0.01). Taken together, our data demonstrate that HIF-1? acts downstream of TNF-? to inhibit VASP expression and to modulate the acute pulmonary inflammation process, and these molecules play an important role in the impairment of the alveolar-capillary barrier.

SUBMITTER: Tang M 

PROVIDER: S-EPMC4106849 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature