Department of Pediatrics, Division of Critical Care Medicine, Cincinnati, OH, USA.
J Inflamm (Lond). 2012 Sep 6;9(1):32. doi: 10.1186/1476-9255-9-32.
Serine proteases in German cockroach (GC) have been shown to mediate allergic airway inflammation through the activation of protease activated receptor (PAR)-2. Neutrophils play an important role in regulating the innate immune response, and are recruited into the airways following GC frass exposure. As such, we investigated the role of PAR-2 in airway neutrophil recruitment, activation and cytokine production following allergen exposure.
Wild type and PAR-2-deficient mice were administered a single intratracheal instillation of PBS or GC frass and neutrophil recruitment, expression of PAR-2, CD80, CD86, and MHC class II were assessed by flow cytometry and levels of tumor necrosis factor (TNF)α was assessed by ELISA. Uptake of AlexaFluor 405-labeled GC frass by neutrophils was performed by flow cytometry.
Neutrophil recruitment in the lung and airways following GC frass exposure was significantly decreased in PAR-2-deficient mice compared to wild type mice. GC frass exposure increased the level of PAR-2 on pulmonary neutrophils and increased numbers of PAR-2-positive neutrophils were found in the lungs; however PAR-2 did not play a role in meditating allergen uptake. Comparing wild type and PAR-2-deficient mice, we found that a single exposure to GC frass increased levels of CD80 and CD86 on pulmonary neutrophils, an effect which was independent of PAR-2 expression. Neutrophils isolated from the whole lungs of naïve PAR-2-deficient mice treated ex vivo with GC frass produced significantly less TNFα than in similarly treated wild type neutrophils. Lastly, neutrophils were isolated from the bronchoalveolar lavage fluid of wild type and PAR-2-deficient mice following a single intratracheal exposure to GC frass. Airway neutrophils from PAR-2-deficient mice released substantially decreased levels of TNFα, suggesting a role for PAR-2 in neutrophil-derived cytokine production.
Together these data suggest PAR-2 expression can be upregulated on lung neutrophils following allergen exposure and the consequence is altered release of TNFα which could drive the early innate immune response.
已证实德国蟑螂（GC）中的丝氨酸蛋白酶通过激活蛋白酶激活受体（PAR）-2 来介导过敏性气道炎症。中性粒细胞在调节先天免疫反应中起重要作用，并在接触 GC 粪便后被招募到气道中。因此，我们研究了 PAR-2 在过敏原暴露后气道中性粒细胞募集、激活和细胞因子产生中的作用。
野生型和 PAR-2 缺陷型小鼠接受单次气管内滴注 PBS 或 GC 粪便，通过流式细胞术评估中性粒细胞募集、PAR-2、CD80、CD86 和 MHC 类 II 的表达，并通过 ELISA 评估肿瘤坏死因子（TNF）α 的水平。通过流式细胞术检测 AlexaFluor 405 标记的 GC 粪便被中性粒细胞摄取的情况。
与野生型小鼠相比，PAR-2 缺陷型小鼠接触 GC 粪便后肺部和气道中的中性粒细胞募集明显减少。GC 粪便暴露增加了肺中性粒细胞上的 PAR-2 水平，并且在肺部发现了更多的 PAR-2 阳性中性粒细胞；然而，PAR-2 在介导过敏原摄取中不起作用。比较野生型和 PAR-2 缺陷型小鼠，我们发现单次接触 GC 粪便会增加肺中性粒细胞上的 CD80 和 CD86 水平，这种作用与 PAR-2 表达无关。体外用 GC 粪便处理的 naive PAR-2 缺陷型小鼠的全肺中性粒细胞中产生的 TNFα 水平明显低于类似处理的野生型中性粒细胞。最后，从野生型和 PAR-2 缺陷型小鼠的支气管肺泡灌洗液中分离气道中性粒细胞。来自 PAR-2 缺陷型小鼠的气道中性粒细胞释放的 TNFα 水平显著降低，表明 PAR-2 在中性粒细胞衍生细胞因子产生中起作用。
这些数据表明，过敏原暴露后肺中性粒细胞上的 PAR-2 表达可以上调，其结果是 TNFα 的释放发生改变，这可能驱动早期先天免疫反应。
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