Evidence that bone marrow-derived mesenchymal stem cells reduce epithelial permeability following phosgene-induced acute lung injury via activation of wnt3a protein-induced canonical wnt/β-catenin signaling

An increase in epithelial cell permeability has been proposed to contribute to phosgene-induced acute lung injury (ALI). However, no specific and effective means for blocking increases in permeability are currently available. Cell-based therapy using bone marrow-derived mesenchymal stem cells (MSCs) is an attractive new approach. Canonical wnt/β-catenin signaling has been demonstrated to contribute to both epithelial cell injury and repair mechanisms in ALI. The goal of our study was to determine the effects of MSCs on epithelial permeability in phosgene-induced ALI in Sprague–Dawley (SD) rats and identify changes in major components of the wnt3a/β-catenin signaling pathway during this process. Epithelial cell permeability was evaluated by measuring total protein, albumin, keratinocyte growth factor, and occludin in bronchoalveolar lavage fluid and lung tissue. MSCs-harboring lentiviral vectors expressing green fluorescent protein (GFP) were used to determine rates of MSC engraftment at injured sites. Lung tissue was excised to evaluate changes in the levels of proteins that function in wnt3a/β-catenin signaling, including wnt3a, total β-catenin, non-phosphorylated-Ser33/37/Thr41 β-catenin, axin2, and cyclin D1 by western blot analysis. Because TGF-β1 and wnt5a can inhibit canonical wnt/β-catenin signaling, we also measured levels of TGF-β1 and wnt5a by western blotting.

Conclusions: (1) TGF-β1 and wnt5a expression correlated with inhibition of wnt3a/β-catenin signaling in our phosgene-induced ALI model and (2) exogenously supplied MSCs homed to sites of lung injury and reduced epithelial permeability likely by blocking TGF-β1- and wnt5a-mediated inhibition of wnt3/β-catenin signaling.     

Ethyl pyruvate protects rats from phosgene‐induced pulmonary edema by inhibiting cyclooxygenase2 and inducible nitric oxide synthase expression

Phosgene is a poorly water‐soluble gas penetrating the lower respiratory tract which can induce acute lung injury characterized by a latent phase of fatal pulmonary edema. Pulmonary edema caused by phosgene is believed to be a consequence of oxidative stress and inflammatory responses. Ethyl pyruvate (EP) has been demonstrated to have anti‐inflammatory and anti‐oxidative properties in vivo and in vitro. The potential therapeutic role of EP in phosgene‐induced pulmonary edema has not been addressed so far. In the present study, we aim to investigate the protective effects of EP on phosgene‐induced pulmonary edema and the underlying mechanisms. Rats were administered with EP (40 mg kg^?1) and RAW264.7 cells were also incubated with it (0, 2, 5 or 10 µm ) immediately after phosgene (400 ppm, 1 min) or air exposure. Wet‐to‐dry lung weight ratio (W:D ratio), nitric oxide (NO) and prostaglandin E₂ (PGE₂) production, cyclooxygenase2 (COX‐2) and inducible nitric oxide synthase (iNOS) expression, and mitogen‐activated protein kinases activities (MAPKs) were measured. Our results showed that EP treatment attenuated phosgene‐induced pulmonary edema and decreased the level of NO and PGE₂ dose‐dependently. Furthermore, EP significantly reduced COX‐2 expression, iNOS expression and MAPK activation induced by phosgene. Moreover, specific inhibitors of MAPKs reduced COX‐2 and iNOS expression induced by phosgene. These findings suggested that EP has a protective role against phosgene‐induced pulmonary edema, which is mediated in part by inhibiting MAPK activation and subsequently down‐regulating COX‐2 and iNOS expression as well as decreasing the production of NO and PGE₂. Copyright © 2011 John Wiley & Sons, Ltd.     

高氧液治疗家兔光气中毒急性肺损伤

目的 :探讨高氧液对兔光气中毒性肺损伤的治疗作用 .方法 :新西兰大白兔 4 2只随机分为 7组 (n =6 ) .染毒组分高浓度组和低浓度组 ,其中高浓度组又分为高浓度光气中毒组 (染毒后不输液 ,HP组 )、平衡盐治疗组 (静脉输入平衡盐30mL·kg-1,HPB组 )及高氧液治疗组 (静脉输入高氧液 30mL·kg-1,HPH组 ) ;低剂量组也分为 3组 :低浓度光气中毒组(LP组 )、平衡盐治疗组 (LPB组 )和高氧液治疗组 (LPH组 ) ;阴性对照组 (C组 )吸入新鲜空气 .高浓度染毒组记录动物染毒后生存时间 ,低浓度染毒组均在染毒后 1,3,8和 12h抽取动脉血样作血气分析 ,12h后处死 ,开胸取肺 ,测定肺湿干比 (W·D-1)、肺水含量 (LW )和肺系数 (L·B-1) ,留取部分肺组织作组织病理学检查 .C组吸入空气后处理同低浓度染毒组 .结果 :HPH组与HP ,HPB组比较 ,生存时间明显延长 (P<0 .0 5 ) ,HP组与HPB组比较无显著差异 (P >0 .0 5 ) .LPH组在输入高氧液后PaO2 明显高于LPB ,LP组 (P <0 .0 1) ;LPH组W·D-1,LW和L·B-1均明显低于LPB ,LP组 (P <0 .0 5 ) .结论 :静脉输注高氧液治疗能减轻光气中毒造成的急性肺组织损伤     

Pulmonary changes in the rat following low phosgene exposure

Minimal inhalation doses (or concentrations) of phosgene necessary for the production of changes within the blood-air barrier were determined in rats. At least 50 ppm.min (5 ppm×10 min) was necessary for the production of alveolar oedema (the minimal effective phosgene concentration being 5 ppm). While the smallest phosgene dose to produce an increase in pulmonary lavage protein content was also 50 ppm.min and while the smallest phosgene dose to produce widening of pulmonary interstices was 25 ppm.min, there was no phosgene threshold concentration (down to 0.1 ppm) for these two latter parameters, which are assumed to be indicators of physiological compensatory mechanisms within the blood-air barrier.The primary localisation of pulmonary damage seemed to depend on the concentration of phosgene used: at low concentrations (0.1–2.5 ppm) the changes were primarily located at the transition from terminal brochioles to the alveolar ducts; at higher concentrations (5 ppm) damage to the alveolar pneumocytes (type I) was more conspicuous.Dedicated to Professor Dr. Dr. H. Meessen     

急性光气中毒患者23例临床分析

目的:总结急性光气中毒的临床特点。方法:收集23例急性光气中毒患者的临床资料,对发病时间、初发临床表现、诊治结果进行综合分析。结果:重度组的潜伏期显著短于轻度组(P0.01)。光气中毒主要初发症状为咳嗽(82.61%)、胸闷(69.57%)等呼吸道症状。重度组呼吸频率、心率、外周血白细胞计数、中性粒细胞百分比、肌酸激酶及其同工酶、肌钙蛋白等实验室检查指标均高于轻、中度组(P0.05～P0.01)。23例患者均存活。结论:急性光气中毒的临床表现主要集中在呼吸系统;根据病情轻重及早短程给予适当剂量糖皮质激素治疗,合理呼吸支持是防止病情恶化、保证抢救成功的关键。