Cena Jonathan, Lalu Manoj M, Rosenfelt Cory, Schulz Richard
Department of Pharmacology, Cardiovascular Research Group, University of Alberta, Edmonton, Alberta, Canada.
Eur J Pharmacol. 2008 Mar 17;582(1-3):116-22. doi: 10.1016/j.ejphar.2007.12.019. Epub 2007 Dec 28.
Septic shock remains the leading cause of death in intensive care units in North America. Recent evidence implicates matrix metalloproteinases (MMP) in the pathogenesis of sepsis. MMP activity is upregulated in blood vessels exposed to bacterial lipopolysaccharide (LPS) or pro-inflammatory cytokines and contributes to vascular hyporeactivity to vasoconstrictors. The exact mechanism of MMP-mediated vascular hyporeactivity is unknown. We investigated the contribution of the endothelium in the MMP response to LPS-mediated vascular hyporeactivity in vitro. Tone induced by phenylephrine in isolated rat aortic rings with either intact or denuded endothelium was measured in the presence of LPS for 6 h. These rings were incubated with the nitric oxide (NO) synthase inhibitor, N(G)-nitro-l-arginine methyl ester (l-NAME), to determine whether NO synthase was involved in the response, or the MMP inhibitors, doxycycline or GM6001. MMP activity was measured after 6 h. LPS caused a greater reduction of phenylephrine-induced tone in endothelium-intact rings versus endothelium-denuded rings, indicating both endothelium-independent and -dependent mechanisms for LPS-induced vascular hyporeactivity. l-NAME abolished the response to LPS in both endothelium-intact and endothelium-denuded rings. MMP inhibitors prevented the LPS-induced loss of tone in endothelium-intact but not endothelium-denuded rings. LPS caused significantly greater MMP-2 activity in endothelium-intact aortae which was attenuated by doxycycline. MMP-2 activity in endothelium-denuded aortae was unchanged by LPS. The vascular endothelium contributes to MMP-mediated vascular dysfunction induced by LPS. The protective effect of MMP inhibition is endothelium-dependent and is a novel mechanism by which MMPs contribute to vascular dysfunction.
脓毒性休克仍然是北美重症监护病房死亡的主要原因。最近的证据表明基质金属蛋白酶（MMP）参与了脓毒症的发病机制。在暴露于细菌脂多糖（LPS）或促炎细胞因子的血管中，MMP活性上调，并导致血管对血管收缩剂反应性降低。MMP介导血管反应性降低的确切机制尚不清楚。我们在体外研究了内皮细胞在MMP对LPS介导的血管反应性降低中的作用。在LPS存在的情况下，测量苯肾上腺素在有完整内皮或去内皮的离体大鼠主动脉环中诱导的张力6小时。这些环与一氧化氮（NO）合酶抑制剂N（G）-硝基-L-精氨酸甲酯（L-NAME）一起孵育，以确定NO合酶是否参与该反应，或与MMP抑制剂强力霉素或GM6001一起孵育。6小时后测量MMP活性。与去内皮环相比，LPS导致完整内皮环中苯肾上腺素诱导的张力降低幅度更大，表明LPS诱导血管反应性降低存在内皮非依赖性和依赖性机制。L-NAME消除了完整内皮环和去内皮环对LPS 的反应。MMP抑制剂可防止LPS诱导的完整内皮环张力丧失，但不能防止去内皮环的张力丧失。LPS导致完整内皮主动脉中MMP-2活性显著升高，强力霉素可使其减弱。LPS对去内皮主动脉中的MMP-2活性无影响。血管内皮细胞参与了LPS诱导的MMP介导的血管功能障碍。MMP抑制的保护作用依赖于内皮细胞，是MMP导致血管功能障碍的一种新机制。
