TRPV1激活对内毒素血症小鼠肺组织炎症损伤的影响及机制

Effect of TRPV1 activation on lipopolysaccharide-induced lung inflammatory injury in mice

目的:探讨用辣椒素(CAP)激活瞬时受体电位阳离子通道V亚族成员1(TRPV1)对内毒素血症所致肺损伤在炎症反应产生的影响及相关机制。方法:SPF级ICR小鼠108只随机分为6组:正常对照组、CAP对照组、抗辣椒碱(CAPZ)对照组、内毒素血症组、CAP干预组和CAPZ干预组。脂多糖(LPS)经腹腔注射,CAP及CAPZ均在LPS注射前30 min经皮下注射。分别在LPS注射后3 h、8 h和16 h取肺组织,ELISA法检测肺组织TNF-α、IL-6、IL-10、P物质(SP)和降血钙素基因相关肽(CGRP),Western blotting法检测肺组织Toll样受体4(TLR4)和核内NF-κB的表达水平,光镜下观察肺组织病理学改变。结果:内毒素血症组小鼠3 h、8 h和16 h肺组织TNF-α、IL-6和IL-10水平较正常对照组均显著升高(P<0.05);CAP干预组各时点肺组织TNF-α和IL-6水平较内毒素血症组显著降低(P<0.05),而IL-10均明显升高(P<0.05);CAPZ干预组3 h、8 h和16 h肺组织TNF-α和IL-6较内毒素血症组显著升高(P<0.05),而IL-10水平均显著降低(P<0.05)。内毒素血症组和CAP对照组各时间点SP和CGRP较正常对照组均显著升高(P<0.05),CAP对照组SP和CGRP水平明显低于内毒素血症组(P<0.05);与同时点内毒素血症组相比,CAP干预组SP和CGRP显著升高(P<0.05),而CAPZ干预组显著降低(P<0.05)。内毒素血症组小鼠肺组织TLR4和核内NF-κB表达较正常对照组显著升高(P<0.05);与内毒素血症组相比,CAP干预组和CAPZ干预组小鼠肺组织TLR4表达均无显著差异(P>0.05),而CAP干预组核内NF-κB表达显著降低(P<0.05),CAPZ干预组核内NF-κB表达显著升高(P<0.05)。光镜下,CAP对照组和CAPZ对照组较正常对照组病理学变化不明显,内毒素血症组肺组织在8 h和16 h损害明显,CAP干预组较内毒素血症组损害减轻,CAPZ干预组较内毒素血症组肺组织损害加重。结论:TRPV1激活后能显著降低内毒素血症小鼠肺组织TNF-α、IL-6和核内NF-κB水平,升高IL-10水平,提高肺组织SP和CGRP表达,减轻肺组织炎症损伤程度,但不改变肺组织TLR4水平。

AIM ： To investigate the effects of transient receptor potential cation channel subfamily V member 1 （ TRPV1 ） activation by capsaicin on the inflammation and its underlying mechanisms in lipopolysaccharide （LPS） -induced lung injury in mice. METHODS： A total of 108 specific pathogen-free male ICR mice were randomly divided into 6 groups： normal control group, capsaicin （CAP） control group, capsazepine （CAPZ） control group, endotoxemia group, CAP treatment group and CAPZ treatment group. LPS was intraperitoneally injected 30 min after the subcutaneous injection of CAP or CAPZ. After modehng, the levels of tumor necrosis factor α（TNF-α） , interleukin 6 （ IL-6）, IL-10, substance P （SP） and calcitonin gene-related peptide （CGRP） in the lung were measured by ELISA. The expression of Toll-like re- ceptor 4 （TLR4） and nuclear factor KB （NF-KB） in the lung tissue was assessed by Western blotting. The pathological changes of the lung tissue were observed under light microscope. RESULTS： The expression of TNF-ct, IL-6, IL-IO and NF-KB in the lung tissues at 3 h, 8 h and 16 h was dramatically higher in endotoxemia group than that in normal control group. Compared with endotoxemia group, the levels of TNF-ct, IL-6 and nuclear NF-KB in CAP treatment group at 3 h, 8 h and 16 h were obviously decreased, but the level of IL-10 was increased. The changes of the factors mentioned above in CAPZ treatment group were absolutely adverse to those in CAP treatment group. The levels of SP and CGRP were signifi- cantly higher in endotoxemia group and CAP control group than those in normal control group, but those in CAPZ control group were lower. Compared with endotoxemia group, SP and CGRP were markedly increased in CAP treatment group and were obviously decreased in CAPZ treatment group. The level of TLR4 in endotoxemia group was distinctly higher than that in normal control group at 3 h, 8 h and 16 h. However, as compared with endotoxemia group, the expression of TLR4 in CAP treatment group and CAPZ treatment group didn＇ t change much. At 8 h and 16 h after modeling, the degree of lung damage was also decreased in CAP treatment group as compared with endotoxemia group, while that in CAPZ treatment group was aggravated. CONCLUSION： TRPV1 activation obviously inhibits the increase in TNF-ct, IL-6 and NF-KB in the lung tissue of endotoxemia mice, and promotes the increase in the anti-inflammatory factor IL-10, as well as the levels of SP and CGRP, but has no effect on the expression of TLR4. [ KEY WORDS] Transient receptor potential cation channel, subfamily V, member 1; Endotoxemia; NF-kappa B; Cytokines; Toll-like receptor 4