Benjamim Claudia Farias, Silva João Santana, Fortes Zuleica Bruno, Oliveira Maria Aparecida, Ferreira Sérgio Henrique, Cunha Fernando Queiroz
Department of Pharmacology, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto SP, Brazil.
Infect Immun. 2002 Jul;70(7):3602-10. doi: 10.1128/IAI.70.7.3602-3610.2002.
We developed two models of sepsis with different degrees of severity, sublethal and lethal sepsis, induced by cecal ligation and puncture. Lethal sepsis induced by cecal ligation and puncture (L-CLP) resulted in failure of neutrophil migration to the infection site and high mortality. Treatment of septic animals with aminoguanidine (AG), a nitric oxide (NO) synthase inhibitor, precluded the failure of neutrophil migration and protected the animals from death. However, cytokine-induced NO synthase (iNOS)-deficient (iNOS(-/-)) mice subjected to L-CLP did not present neutrophil migration failure, but 100% lethality occurred. iNOS(-/-) mice subjected to sublethal sepsis induced by cecal ligation and puncture (SL-CLP) also suffered high mortality despite the occurrence of neutrophil migration. This apparent paradox could be explained by the lack of microbicidal activity in neutrophils of iNOS(-/-) mice present at the infection site due to their inability to produce NO. Notably, SL- and L-CLP iNOS(-/-) mice showed high bacterial numbers in exudates. The inhibition of neutrophil migration by NO is due to inhibition of a neutrophil/endothelium adhesion mechanism, since a reduction in leukocyte rolling, adhesion, and emigration was observed in L-CLP wild-type mice. These responses were prevented by AG treatment and were not observed in the iNOS(-/-) L-CLP group. There was no significant change in L-selectin expression in neutrophils from L-CLP mice. Thus, it seems that the decrease in leukocyte rolling is due to a defect in the expression of adhesion molecules on endothelial surfaces mediated by iNOS-derived NO. In conclusion, the results indicate that despite the importance of NO in neutrophil microbicidal activity, its generation in severe sepsis reduces neutrophil migration by inhibiting leukocyte rolling and their firm adhesion to the endothelium, in effect impairing the migration of leukocytes and consequently their fundamental role in host cell defense mechanisms.
我们通过盲肠结扎和穿刺诱导出了两种不同严重程度的脓毒症模型，即亚致死性脓毒症和致死性脓毒症。盲肠结扎和穿刺诱导的致死性脓毒症（L-CLP）导致中性粒细胞向感染部位迁移失败且死亡率高。用一氧化氮（NO）合酶抑制剂氨基胍（AG）治疗脓毒症动物，可防止中性粒细胞迁移失败并保护动物免于死亡。然而，接受L-CLP的细胞因子诱导型NO合酶（iNOS）缺陷（iNOS(-/-)）小鼠未出现中性粒细胞迁移失败，但出现了100%的致死率。接受盲肠结扎和穿刺诱导的亚致死性脓毒症（SL-CLP）的iNOS(-/-)小鼠尽管出现了中性粒细胞迁移，但死亡率也很高。这种明显的矛盾可以解释为，由于iNOS(-/-)小鼠的中性粒细胞无法产生NO，其在感染部位缺乏杀菌活性。值得注意的是，SL-CLP和L-CLP的iNOS(-/-)小鼠渗出物中的细菌数量很高。NO对中性粒细胞迁移的抑制是由于对中性粒细胞/内皮细胞黏附机制的抑制，因为在L-CLP野生型小鼠中观察到白细胞滚动、黏附和渗出减少。AG治疗可防止这些反应，而在iNOS(-/-) L-CLP组中未观察到这些反应。L-CLP小鼠中性粒细胞中的L-选择素表达没有显著变化。因此，白细胞滚动的减少似乎是由于iNOS衍生的NO介导的内皮表面黏附分子表达缺陷所致。总之，结果表明，尽管NO在中性粒细胞杀菌活性中很重要，但在严重脓毒症中其产生通过抑制白细胞滚动及其与内皮细胞的牢固黏附而减少中性粒细胞迁移，实际上损害了白细胞的迁移，从而损害了它们在宿主细胞防御机制中的基本作用。
