Inhibition of Alveolar Macrophage Pyroptosis Reduces Lipopolysaccharide-induced Acute Lung Injury in Mice / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Pyroptosis is the term for caspase-1-dependent cell death associated with pro-inflammatory cytokines. The role of alveolar macrophage (AM) pyroptosis in the pathogenesis of the acute lung injury and acute respiratory distress syndrome (ALI/ARDS) remains unclear.</p><p><b>METHODS</b>C57BL/6 wild-type mice were assigned to sham, lipopolysaccharide (LPS) + vehicle, LPS + acetyl-tyrosyl-valyl- alanyl-aspartyl-chloromethylketone (Ac-YVAD-CMK) and LPS + Z-Asp-Glu-Val-Asp-fluoromethylketone groups. Mice were given intraperitoneal (IP) injections of LPS. Drugs were IP injected 1 h before LPS administration. Mice were sacrificed 16 h after LPS administration, and AMs were isolated. Western blot analysis for active caspase-1 and cleaved caspase-3, evaluation of lung injury and a cytokine release analysis were performed. AMs were treated with LPS and adenosine triphosphate (ATP); caspase-1-dependent cell death was evaluated using flow cytometry; the apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) pyroptosomes were examined by immunofluorescence.</p><p><b>RESULTS</b>The expression of activated caspase-1 in AMs was enhanced following LPS challenge compared with the sham group. In the ex vivo study, the caspase-1/propidium iodide-positive cells, caspase-1 specks and ASC pyroptosomes were up-regulated in AMs following LPS/ATP stimulation. The specific caspase-1 inhibitor Ac-YVAD-CMK inhibited the activation of caspase-1 and pyroptotic cell death. Ac-YVAD-CMK also reduced the lung injury, pulmonary edema and total protein in bronchoalveolar lavage fluid (BALF). In addition, Ac-YVAD-CMK significantly inhibited interleukin-α2 (IL-1α2) release both in serum and BALF and reduced the levels of IL-18, tumor necrosis factor-α± (TNF-α±), High Mobility Group Box 1 (HMGB1) in BALF during LPS-induced ALI/ARDS.</p><p><b>CONCLUSIONS</b>This study reported AM pyroptosis during LPS-induced ALI/ARDS in mice and has demonstrated that Ac-YVAD-CMK can prevent AM-induced pyroptosis and lung injury. These preliminary findings may form the basis for further studies to evaluate this pathway as a target for prevention or reduction of ALI/ARDS.</p>

Inhibition of nuclear factor-κB activity enhanced chemosensitivity to cisplatin in human lung adeno-carcinoma A549 cells under chemical hypoxia conditions / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Tumor hypoxia, one of the features of solid tumors, is associated with chemo-resistance. Recently, nuclear factor-κB (NF-κB) was found to be activated during hypoxia. However, the impact of NF-κB activation on chemo-resistance during hypoxia remains unknown.</p><p><b>METHODS</b>Human lung adenocarcinoma A549 cells were transfected with NF-κB p65siRNA and treated with cobalt chloride (CoCl2) to mimic hypoxia in the presence or absence of cisplatin. NF-κB expression was measured by Western blotting, immune-fluorescence and real-time PCR. Hypoxia-inducible factor-1α (HIF-1α) and Bcl-2 expression were determined by Western blotting. Cell apoptosis and survival with half-maximum inhibitory concentration (IC50) of cisplatin were determined by Annexin V-FITC/PI and 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT), respectively.</p><p><b>RESULTS</b>Exposure of A549 cells to CoCl2 increased nuclear HIF-1a protein expression, and enhanced NF-κB p65 protein nuclear accumulation (the mark of NF-κB activation) in a time and dose dependant manner. CoCl2 did not promote apoptosis in A549 cells; on the contrary, it reduced cisplatin-induced apoptosis and increased the IC50 of cisplatin. However, when we inhibited CoCl2-induced activation of NF-κB through NF-κB p65siRNA, cisplatin-induced apoptosis was increased and IC50 of cisplatin was reduced to levels similar to those in control cells. Meanwhile, CoCl2-induced Bcl-2 overexpression was down-regulated in the presence of cisplatin when NF-κB activity was inhibited.</p><p><b>CONCLUSION</b>Up-regulating Bcl-2 might be involved in NF-κB activation induced resistance to cisplatin in A549 cells under CoCl2-induced chemical hypoxia.</p>