Meldrum D R, McIntyre R C, Sheridan B C, Cleveland J C, Fullerton D A, Harken A H
Department of Surgery, University of Colorado Health Sciences Center, Denver 80262, USA.
J Trauma. 1997 Dec;43(6):888-93. doi: 10.1097/00005373-199712000-00003.
Recent clinical reports indicate that inhaled nitric oxide (NO) reduces lung parenchymal inflammation during acute lung injury; however, the mechanism of its protective effects remains incompletely understood. We hypothesized that the provision of substrate for local NO production (L-arginine) would reduce alveolar macrophage proinflammatory monokine production during endotoxin (ETX)-induced acute lung injury. Our purposes were to (1) determine alveolar macrophage tumor necrosis factor alpha (TNFalpha) and interleukin 1beta (IL-1beta) production after ETX-induced acute lung injury; (2) determine the effect of L-arginine on alveolar macrophage TNFalpha and IL-1beta production in ETX-induced acute lung injury; and (3) determine whether L-arginine's effects on the alveolar macrophage are mediated by NO.
Rats received ETX (0.5 mg/kg intraperitoneal (i.p.)) or vehicle, with or without (1) L-arginine supplementation (300 mg/kg i.p.) and (2) nitric oxide synthase inhibition (N(G)-monomethyl-L-arginine, 30 mg/kg i.p.). Four hours later, alveolar macrophage were harvested by bronchoalveolar lavage and incubated at 10(6) cells/mL + 1 microg/mL phorbol myristase acetate for 24 hours. Cell-free supernatants were collected and assayed (enzyme-linked immunosorbent assay) for TNFalpha and IL-1beta.
Sublethal ETX increased alveolar macrophage capacity to produce TNFalpha and IL-1beta (p < 0.05, analysis of variance and Bonferroni/Dunn). L-Arginine decreased alveolar macrophage TNFalpha and IL-1beta release during acute lung injury. Concurrent inhibition of nitric oxide synthase abrogated L-arginine's protective effects, suggesting that L-arginine's anti-inflammatory effects are mediated by NO.
(1) L-Arginine is an immunomodulating nutritional supplement; (2) L-arginine decreases alveolar macrophage proinflammatory monokine production during ETX-induced acute lung injury by a nitric oxide synthase-dependent mechanism; and (3) the provision of exogenous substrate for local NO production may reduce inflammation during acute lung injury.
近期临床报告表明，吸入一氧化氮（NO）可减轻急性肺损伤期间的肺实质炎症；然而，其保护作用的机制仍未完全明确。我们推测，为局部NO生成提供底物（L-精氨酸）会减少内毒素（ETX）诱导的急性肺损伤期间肺泡巨噬细胞促炎单核因子的产生。我们的目的是：（1）确定ETX诱导的急性肺损伤后肺泡巨噬细胞肿瘤坏死因子α（TNFα）和白细胞介素1β（IL-1β）的产生情况；（2）确定L-精氨酸对ETX诱导急性肺损伤时肺泡巨噬细胞TNFα和IL-1β产生的影响；（3）确定L-精氨酸对肺泡巨噬细胞的作用是否由NO介导。
大鼠接受ETX（0.5mg/kg腹腔注射（i.p.））或赋形剂，同时给予或不给予（1）L-精氨酸补充剂（300mg/kg腹腔注射）和（2）一氧化氮合酶抑制剂（N(G)-单甲基-L-精氨酸，30mg/kg腹腔注射）。4小时后，通过支气管肺泡灌洗收集肺泡巨噬细胞，并在10(6)个细胞/mL + 1μg/mL佛波酯肉豆蔻酸酯乙酸酯的条件下孵育24小时。收集无细胞上清液并进行检测（酶联免疫吸附测定），以测定TNFα和IL-1β。
亚致死剂量的ETX增加了肺泡巨噬细胞产生TNFα和IL-1β的能力（p < 0.05，方差分析和Bonferroni/Dunn检验）。L-精氨酸减少了急性肺损伤期间肺泡巨噬细胞TNFα和IL-1β的释放。同时抑制一氧化氮合酶消除了L-精氨酸的保护作用，表明L-精氨酸的抗炎作用由NO介导。
（1）L-精氨酸是一种免疫调节营养补充剂；（2）L-精氨酸通过一氧化氮合酶依赖性机制减少ETX诱导的急性肺损伤期间肺泡巨噬细胞促炎单核因子的产生；（3）为局部NO生成提供外源性底物可能会减轻急性肺损伤期间的炎症。
