Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Denver, Anschutz Medical Campus, Research 2, Box C272, 9th Floor, 12700 East 19th Avenue, Aurora, CO 80045, USA.
Alcohol Clin Exp Res. 2010 Oct;34(10):1723-32. doi: 10.1111/j.1530-0277.2010.01259.x. Epub 2010 Jul 1.
Alcohol abuse increases the risk for acute respiratory distress syndrome (ARDS). Efferocytosis, the clearance of apoptotic cells, is important in the resolution of inflammation and is regulated by RhoA and rho kinase (ROCK) activation. The effects of alcohol on pulmonary Rho pathway activation and efferocytosis have not been determined. We hypothesize that acute and chronic alcohol exposure impair pulmonary efferocytosis, leading to heightened inflammation during ARDS.
For in vivo experiments, C57BL/6 mice received either a single intraperitoneal injection of alcohol or chronic ethanol-in-water for 8 weeks prior to intratracheal instillation of apoptotic cells or lipopolysaccharide (LPS). Bronchoalveolar lavage (BAL) was performed for cells counts, calculation of the phagocytic index (PI), and Rho activity measurements. For in vitro studies, primary alveolar macrophages were cultured in alcohol (25-100 mM) and then co-cultured with apoptotic cells. RhoA activity was determined following alcohol exposure, and the PI was determined before and after treatment with the ROCK inhibitor, Y27632.
Acute alcohol exposure was associated with impaired efferocytosis. Following LPS exposure, acute alcohol exposure was also associated with increased BAL neutrophils. Chronic alcohol exposure alone did not alter efferocytosis. However, following exposure to LPS, chronic alcohol exposure was associated with both impaired efferocytosis and increased BAL neutrophils. In vitro alcohol exposure caused a dose-dependent decrease in efferocytosis. Despite the fact that RhoA activity was decreased by alcohol exposure and RhoA inhibition did not alter the effects of alcohol on efferocytosis, treatment with the Rho kinase inhibitor, Y27632, reversed the effects of alcohol on efferocytosis.
Acute alcohol exposure impairs pulmonary efferocytosis, whereas exposure to chronic alcohol is only associated with impaired efferocytosis following LPS-induced lung injury. Both forms of alcohol exposure are associated with increased alveolar neutrophil numbers in response to LPS. The acute effects of alcohol on efferocytosis appear to be mediated, at least in part, by RhoA-independent activation of ROCK. Further studies are needed to dissect the differences between the effects of acute and chronic alcohol exposure on efferocytosis and to determine the effects of alcohol on alternative activators of ROCK.
酗酒会增加急性呼吸窘迫综合征（ARDS）的风险。吞噬作用，即清除凋亡细胞，对于炎症的消退很重要，并且受到 RhoA 和 rho 激酶（ROCK）激活的调节。酒精对肺 Rho 通路激活和吞噬作用的影响尚未确定。我们假设急性和慢性酒精暴露会损害肺吞噬作用，导致 ARDS 期间炎症加剧。
对于体内实验，C57BL/6 小鼠在气管内滴注凋亡细胞或脂多糖（LPS）之前，接受单次腹腔内注射酒精或慢性乙醇水 8 周。进行支气管肺泡灌洗（BAL）以进行细胞计数、吞噬指数（PI）计算和 Rho 活性测量。对于体外研究，将原代肺泡巨噬细胞在酒精（25-100 mM）中培养，然后与凋亡细胞共培养。在酒精暴露后测定 RhoA 活性，并在使用 ROCK 抑制剂 Y27632 治疗前后测定 PI。
急性酒精暴露与吞噬作用受损有关。在 LPS 暴露后，急性酒精暴露也与 BAL 中性粒细胞增多有关。单独的慢性酒精暴露不会改变吞噬作用。然而，在暴露于 LPS 后，慢性酒精暴露与吞噬作用受损和 BAL 中性粒细胞增多均有关。体外酒精暴露导致吞噬作用呈剂量依赖性下降。尽管 RhoA 活性因酒精暴露而降低，并且 RhoA 抑制不改变酒精对吞噬作用的影响，但 Rho 激酶抑制剂 Y27632 的治疗逆转了酒精对吞噬作用的影响。
急性酒精暴露会损害肺吞噬作用，而慢性酒精暴露仅在 LPS 诱导的肺损伤后与吞噬作用受损有关。两种形式的酒精暴露均与 LPS 反应性肺泡中性粒细胞数量增加有关。酒精对吞噬作用的急性影响至少部分是通过 RhoA 非依赖性 ROCK 激活介导的。需要进一步研究来剖析急性和慢性酒精暴露对吞噬作用的影响，并确定酒精对 ROCK 替代激活剂的影响。
