Increased surfactant protein D fails to improve bacterial clearance and inflammation in serpinB1-/- mice.
Increased surfactant protein D fails to improve bacterial clearance and inflammation in serpinB1-/- mice.
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DOI：
10.1165/rcmb.2012-0145oc
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发表时间：
2012-09
影响因子：
6.4
通讯作者：
J. Stolley;Dapeng Gong;K. Farley;P. Zhao;J. Cooley;E. Crouch;C. Benarafa;E. Remold-O’Donnell
中科院分区：
文献类型：
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作者：
J. Stolley;Dapeng Gong;K. Farley;P. Zhao;J. Cooley;E. Crouch;C. Benarafa;E. Remold-O’Donnell
先前，我们描述了中性粒细胞丝氨酸蛋白酶抑制剂serpinB 1通过促进细菌清除和限制炎性细胞因子和蛋白水解损伤在预防铜绿假单胞菌肺部感染早期死亡中的保护作用。表面活性蛋白D（SP-D），维持肺内环境和介导细菌清除，在感染的serpinB 1缺陷小鼠中降解。基于增加SP-D将拯救或减轻serpinB 1缺失的病理效应的假设，我们产生了两个过表达肺特异性大鼠SP-D的serpinB 1（-/-）系，并用铜绿假单胞菌接种小鼠。与预测相反，SP-D（低）serpinB 1（-/-）和SP-D（高）serpinB 1（-/-）小鼠肺中的细菌计数比野生型高4个对数，与serpinB 1（-/-）小鼠无差异。SP-D过表达也未能减轻炎症（TNF-α）、肺损伤（游离蛋白、白蛋白）或过度中性粒细胞死亡（游离髓过氧化物酶、弹性蛋白酶）。感染SP-D（高）serpinB 1（-/-）小鼠的这些病理标志物高于serpinB 1（-/-）小鼠，尽管在控制多重比较后差异不显著。转基因SP-D未能拯救serpinB 1缺陷小鼠的抗菌防御，尽管表达水平增加了5倍或20倍，结构基本正常，并且具有剂量依赖性的细菌聚集活性。通过还原性SDS-PAGE，感染的野生型小鼠的SP-D在43-kD单体中是完整的。相比之下，在感染的SP-D（低）serpinB 1（-/-）、SP-D（高）serpinB 1（-/-）小鼠和serpinB 1（-/-）小鼠中发现35、17和8 kD的蛋白水解片段。因此，尽管增加SP-D肺浓度的疗法可能具有有益的应用，但研究结果表明，如果潜在的临床病症包括过度蛋白水解，则SP-D疗法可能对肺部炎症或感染无益。
Previously, we described the protective role of the neutrophil serine protease inhibitor serpinB1 in preventing early mortality of Pseudomonas aeruginosa lung infection by fostering bacterial clearance and limiting inflammatory cytokines and proteolytic damage. Surfactant protein D (SP-D), which maintains the antiinflammatory pulmonary environment and mediates bacterial removal, was degraded in infected serpinB1-deficient mice. Based on the hypothesis that increased SP-D would rescue or mitigate the pathological effects of serpinB1 deletion, we generated two serpinB1(-/-) lines overexpressing lung-specific rat SP-D and inoculated the mice with P. aeruginosa. Contrary to predictions, bacterial counts in the lungs of SP-D(low)serpinB1(-/-) and SP-D(high) serpinB1(-/-) mice were 4 logs higher than wild-type and not different from serpinB1(-/-) mice. SP-D overexpression also failed to mitigate inflammation (TNF-α), lung injury (free protein, albumin), or excess neutrophil death (free myeloperoxidase, elastase). These pathological markers were higher for infected SP-D(high)serpinB1(-/-) mice than for serpinB1(-/-) mice, although the differences were not significant after controlling for multiple comparisons. The failure of transgenic SP-D to rescue antibacterial defense of serpinB1-deficient mice occurred despite 5-fold or 20-fold increased expression levels, largely normal structure, and dose-dependent bacteria-aggregating activity. SP-D of infected wild-type mice was intact in 43-kD monomers by reducing SDS-PAGE. By contrast, proteolytic fragments of 35, 17, and 8 kD were found in infected SP-D(low)serpinB1(-/-), SP-D(high) serpinB1(-/-) mice, and serpinB1(-/-) mice. Thus, although therapies to increase lung concentration of SP-D may have beneficial applications, the findings suggest that therapy with SP-D may not be beneficial for lung inflammation or infection if the underlying clinical condition includes excess proteolysis.