血管活性肠肽对肺损伤大鼠Toll样受体mRNA表达的影响

目的 探讨血管活性肠肽(vasoactive intestinal peptide,VIP)对内毒素(脂多糖,lipopolysaceberide,LPS)致休克大鼠肺损伤后Toll样受体(Toll-like receptor,TLR)2和TLR4 mRNA表达的影响.方法 40只SD大鼠,随机分为LPS组(16只)、LPS+VIP组(16只)和对照组(8只).LPS组尾静脉注射LPS(E.coli O_(55)B_5)10 mg/kg;LPS+VIP组尾静脉注射LPS 10 ms/kg后注射VIP 5 nmol/kg;对照组尾静脉注射等容量生理盐水.分别于注射后6 h和24 h处死,留取肺标本,RT-PCR检测肺TLR2/4 mRNA表达,并观察24 h时肺组织病理变化.结果 (1)肺组织病理改变:制模24 h时.光镜和透射电镜下,LPS组见肺泡间隔弥漫性增宽、炎性细胞浸润,隔内毛细血管不同程度充血,肺泡壁增厚,肺泡腔结构破坏、炎性细胞浸润、出血、间质水肿、细胞器破坏,LPS+VIP组病变较轻.(2)TLR2/4 mRNA表达:注射LPS后6 h、24 h,肺组织TLR2/4 mRNA表达升高(F=16.638,P=0.000;t=5.876,P=0.000);24 h时LPs+VIP组TLR2/4 mRNA表达低于LPS组(F=16.676,P=0.000;t=3.9,16,P<0.001).结论 LPS致休克大鼠肺损伤时,肺组织TLR2/4 mRNA表达增强.VIP可减轻LPS所致肺损伤,其机制可能与下调重要炎症基因TLR2/4 mRNA表达有关.

Effects of vasoactive intestinal pcptide on Toll-like receptor(TLR)2 mRNA and TLR4 mRNA expression on acute lung injury induced by Hpopolysach aride in rat

Objective Vasoactive intestinal peptide(VIP)is a neuro-peptide that can modulate immunity.Previous studies indicated that VIP can attenuate the deleterious consequences of severe sepsis and septic shock by regulating production of inflammatory cytokines in immune activated cells.The signaling induced by bacterial components occurs primarily through Toll like receptors(TLRs).TLRs have been recognized to play a key role in pathogen recognition and innate immunity.It was convincingly demonstrated that lung is one of early suffered disaster organ and may trigger multiple organ dysfunction syndrome in sepsis.The present study was conducted to investigate the effects of VIP on TLR2/4,4 mRNA expressions on acute lung injury of endotoxic shock induced by lipolysaccharide(LPS)in rat. Method Forty Sprague-Dawley rats were randomly divided into 3 groups,i.e.,LPS shock group(n=16),LPS+VIP group(n=16),and control group(n=8).LPS shock model was established by LPS(E.coli O_(55)B_5 10 mg/kg)with tail intravenous injection.The rats in LPS+VIP group were given a bolus of 5 nmol VIP intravenous injection follow by LPS.The rats in control group were given normal saline.The rats were sacrificed at 6 h, 24 h after being iniected.The lung tissues were collected.The TLR2 mRNA and TLR4 mRNA expressions were detected by RT-PCR from the lung tissues.Pathological changes of the lungs were observed by light microscope and electron microscope 24 h after LPS injection.Result (1)Lung histopathology:the alveolar space wag full with leukocyte,necrotic cells,segmental hemorrhage and protein effusion.Partial alveo]ar space wag enlarged,lung interstitial edema were observed in LPS 8hock group.However,pathological changes of LPS+VIP group were milder than those in LPS shock group.(2)The expressions of TLR2 mRNA and TLR4 mRNA were significantly higher in LPS shock group compared with those ofthe control group(F= 16.638,P=0.000;t=5.876,P=0.000),TLR2 mRNA and TLR4 mRNA expression on 24 h was down-regulated in LPS+VIP shock subgroup than those in LPS shock subgroup(F=16.676,P=0.000;t=3.946,P<0.001).Conclusion Expressions of TLR2 mRNA and TLR4 mRNA were up-regulated on LPS induced lung injury in rats.VIP mitigated lung injury induced by LPS,which may be related to TLR2 mRNA and TLR4 mRNA down-regulation of expression.The effect of VIP may suggest a protective mechanism in sepsis.VIP may play a potential protective role in severe jnfection.