[Mechanism of lung and intestine combination therapy in treatment of acute lung injury by inhibiting inflammatory response based on NF-κB/NLRP3 signaling pathway and alveolar macrophage activation].

Lung and intestine combination therapy(LICT) is effective in the treatment of acute lung injury(ALI). In this study, the combination of Mahuang Decoction and Dachengqi Decoction(hereinafter referred to as the combination), a manifestation of LICT, was employed to explore the effect of nuclear factor kappaB(NF-κB)/nucleotide binding oligomerization domain-like receptors-3(NLRP3) pathway and alveolar macrophage activation on the lung inflammation in rats with ALI, for the purpose of elucidating the mechanism of LICT in treating ALI. After the modeling of ALI with limpolysaccharide(LPS, ip), rats were respectively given(ig) the combination at 10, 7.5, and 5 g·kg~(-1)(high-dose, medium-dose, and low-dose LICT groups, separately), once every 8 h for 3 times. Haematoxylin-eosin(HE) staining was used to observe the histopathological changes of lung tissue, followed by the scoring of inflammation. Immunohistochemistry was applied to detect alveolar macrophage activation, enzyme-linked immunosorbent assay(ELISA) was applied to detect the serum content of tumor necrosis factor-α(TNF-α) and interleukin-18(IL-18), Western blot was applied to detect the protein expression of phosphorylated-nuclear factor kappaB p65(p-NF-κB p65), nuclear factor kappaB p65(NF-κB p65), phosphorylated-inhibitor kappaB alpha(p-IκBα), inhibitor kappaB alpha(IκBα), and NLRP3 in lung tissue, and quantitative reverse transcription-PCR(qRT-PCR) was applied to detect the mRNA expression of TNF-α, IL-18, NLRP3, and NF-κB p65 in lung tissue. The results showed that LICT groups demonstrated lung injury relief, decrease in inflammation score, alleviation of alveolar macrophage activation, significant decline in serum content of inflammatory factors TNF-α and IL-18, and decrease of the protein expression of p-NF-κB p65/NF-κB p65, p-IκBα/IκBα, and NLRP3, and mRNA expression of TNF-α, IL-18, NLRP3, and NF-κB p65 in lung tissue. In summary, LICT has definite therapeutic effect on ALI. The mechanism is that it inhibits alveolar macrophage activation by suppressing NF-κB/NLRP3 signaling pathway, thereby reducing the activation and release of inflammatory factors and finally inhibiting inflammation.

[Protective Effect of Angiotensin Converting Enzyme 2 (ACE2) Against Chronic Intermittent Hypoxia-induced Pulmonary Oxidative Stress Injury in Rats].

OBJECTIVE: To determine changes of angiotensin converting enzyme 2 (ACE2) in the development of chronic intermittent hypoxia (CIH)-induced pulmonary injury in rats and its mechanism. METHODS: 96 adult male Wistar rats were randomly allocated into four groups: control (UC) group, chronic intermittent hypoxia (CIH) group, normal saline treated CIH (NS) group, and edaravone treated CIH (NE) group. Each group contained four subgroups of rats (n = 6) subjecting to 1 week, 2 weeks, 3 weeks, and 4 weeks experiment, respectively. No intervention was given to rats in the UC group. Rats in the experimental groups were exposed to alternating cycles of nitrogen and compressed air. Rats in the NS and NE groups received daily injection of 0.9% normal saline (3 mg/ kg) and edaravone (3 mg/kg), respectively. Pulmonary sections were taken and stained with hematoxylin-eosin (HE). The levels of malondialdehyde (MDA), ACE2, ACE2 mRNA, and angiotensin II (Ang II) mRNA in the rat homogenate pulmonary samples were measured. RESULTS: Rats in the CIH and NS groups showed high levels of interstitial edema, alveolar atelectasis, and inflammatory cell infiltration in alveolar epithelial cells. The pulmonary injury got worse over time. Rats in the NE group showed later occurrence-and milder pulmonary injury compared with those in the NS group. Rats in the CIH and NS groups had higher levels of MDA and Ang II mRNA (which increased over time) than those in the UC group (P < 0.05). The expression of ACE2 and the level of ACE2 mRNA increased in rats in the CIH group (P < 0.05), and peaked at 2 weeks (P < 0.05). Rats in the NE group had moderately increased levels of MDA and Ang II mRNA compared with those in the NS group (P < 0.05); moderately increased levels of expression of ACE2 and ACE2 mRNA compared with those in the UC and SC groups (P < 0.05). The pulmonary level of Ang II mRNA was positively correlated with MDA (r = 0.782, P < 0.01) in rats in the CIH group. CONCLUSION: CIH can activate oxidation stress and Ang II, which maybe an important mechanism of CIH-induced pulmonary injury.