Studies on a graft-protective effect of nitric oxide in small bowel transplantation

[背景/目的]表皮生长因子(EGF)是小肠移植(SBT)后肠道适应的营养因子之一，已在多种实验动物模型中被证明可预防细菌易位(BT)。一氧化氮(NO)可能是肠源性脓毒症、烧伤损伤、肠道溃疡、肠道病变和SBT的重要保护分子。最近我们发现，表皮生长因子可增加促炎细胞因子白介素1β刺激的大鼠肠上皮细胞产生NO，提示NO可能参与了表皮生长因子对肠道损伤的细胞保护作用。[方法]体外培养的大鼠肠上皮细胞(IEC-6)在药物存在的情况下，用IL-1β/EGF处理，观察诱导型一氧化氮合酶(INOS)和NO产物…的诱导。[结果]在IL-1β/EGF存在的情况下，IEC-6刺激NO的产生。加入抗氧化剂α-硫辛酸和半胱胺、自由基清除剂依达拉奉(日本三菱威力制药)和HMG-CoA还原酶抑制剂/他汀类他汀类药物(日本KOVA)进一步增加了NO的产量。其中，匹伐他汀(10-100μM)与表皮生长因子一样，在IL-1β存在的情况下促进NO的产生，且在50μM浓度时作用最强。匹伐他汀可增加iNOS基因的表达，进而增加iNOS蛋白的表达，进而促进NO的产生。甲羟戊酸是胆固醇生物合成的关键中间体，可被他汀类药物减少，外源添加可阻断NO的增加，以及iNOS mRNA和蛋白的表达增加。[结论]他汀类药物(3-羟基-3-甲基戊二酰辅酶A(HMG-CoA)还原酶抑制剂)最初用于降低血浆胆固醇水平，已被越来越多地认为是抗炎药。我们的结果表明，匹伐他汀上调诱导型一氧化氮合酶的表达，增加一氧化氮的产生，从而对炎症时的肠上皮细胞产生保护作用。Pitavastatin和EGF可能通过调节SBT中NO的产生来促进移植物的适应。较少

[Background/Aims] Epidermal growth factor (EGF), which is one of trophic factors for intestinal adaptation after small bowel transplantation (SBT), has been shown to prevent bacterial translocation (BT) in a variety of experimental animal models. Nitric oxide (NO) may be an important protective molecule against gut-derived sepsis, bum injury, intestinal ulcerogenecity, intestinal lesions, and SBT. Recently we found that EGF increased the production of NO in rat intestinal epithelial cells stimulated by pro-inflammatory cytokine, interleukin (IL)-1β, suggesting that NO may be involved in the cytoprotective effects of EGF against intestinal injury. We examined whether drugs, which have protective effects in various organ injuries, influence the inducible nitric oxide synthase (iNOS) expression and NO production in intestinal epithelium.[Methods] Cultured rat intestinal epithelial cells (IEC-6) were treated with IL-1β /EGF in the presence of drugs, and the induction of iNOS and NO product … More ion was analyzed.[Results] IEC-6 stimulated the production of NO in the presence of IL-1β /EGF. The addition of anti-oxidant such as a-lipoic acid and cysteamine, free radical scavenger edaravone (Mitsubishi Wellpharma, Japan), and HMG-CoA reductase inhibitor/statin pitavastatin (Kowa, Japan) further increased the NO production. Among them, pitavastatin (10-100 μM) accelerated the NO production in the presence of IL-1β as in the case of EGF, showing a maximal effect at the concentration of 50 μM. Pitavastatin alone had no effect on the production of NO. Pitavastatin increased the levels of iNOS mRNA, followed by the increase of iNOS protein, which in turn enhanced the NO production. Exogenous addition of mevalonate, which is a key intermediate of cholesterol biosynthesis and is reduced by statins, blocked the increased production of NO, and increased expression of iNOS mRNA and protein. This suggests that the stimulatory effect of pitavastatin is at least in part through the inhibition of cholesterol biosynthesis.[Conclusion] Statins (3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase inhibitors), which are originally used to lower plasma cholesterol levels, are increasingly recognized as anti-inflammatory agents. Our results indicate that pitavastatin up-regulate the induction of iNOS expression and increase the production of NO, resulting in the protective effect in intestinal epithelial cells during inflammation. Pitavastatin as well as EGF may accelerate the graft adaptation through the regulation of NO production in SBT. Less