Department of Pharmaceutical Sciences, University of Oklahoma Health Sciences Center (OUHSC), Oklahoma City, Oklahoma, United States of America.
Department of Pathology, OUHSC, Oklahoma City, Oklahoma, United States of America.
PLoS One. 2019 Jan 28;14(1):e0210979. doi: 10.1371/journal.pone.0210979. eCollection 2019.
Interaction between surfactant protein-A (SP-A) and toll-like receptor (TLR)4 plays a critical role in host defense. In this work, we studied the host defense function of SPA4 peptide (amino acids GDFRYSDGTPVNYTNWYRGE), derived from the TLR4-interacting region of SP-A, against Pseudomonas aeruginosa. We determined the binding of SPA4 peptide to live bacteria, and its direct antibacterial activity against P. aeruginosa. Pro-phagocytic and anti-inflammatory effects were investigated in JAWS II dendritic cells and primary alveolar macrophages. The biological relevance of SPA4 peptide was evaluated in a mouse model of acute lung infection induced by intratracheal challenge with P. aeruginosa. Our results demonstrate that the SPA4 peptide does not interact with or kill P. aeruginosa when cultured outside the host. The SPA4 peptide treatment induces the uptake and localization of bacteria in the phagolysosomes of immune cells. At the same time, the secreted amounts of TNF-α are significantly reduced in cell-free supernatants of SPA4 peptide-treated cells. In cells overexpressing TLR4, the TLR4-induced phagocytic response is maintained, but the levels of TLR4-stimulated TNF-α are reduced. Furthermore, our results demonstrate that the therapeutic administration of SPA4 peptide reduces bacterial burden, inflammatory cytokines and chemokines, intracellular signaling, and lactate levels, and alleviates lung edema and tissue damage in P. aeruginosa-infected mice. Together, our results suggest that the treatment with SPA4 peptide can help control the bacterial burden, inflammation, and tissue injury in a P. aeruginosa lung infection model.
表面活性蛋白-A（SP-A）与 Toll 样受体（TLR）4 之间的相互作用在宿主防御中起着关键作用。在这项工作中，我们研究了源自 SP-A 与 TLR4 相互作用区域的 SPA4 肽（氨基酸 GDFRYSDGTPVNYTNWYRGE）对铜绿假单胞菌的宿主防御功能。我们确定了 SPA4 肽与活细菌的结合，以及其对铜绿假单胞菌的直接抗菌活性。在 JAWS II 树突状细胞和原代肺泡巨噬细胞中研究了促吞噬和抗炎作用。在铜绿假单胞菌气管内滴注诱导的急性肺感染小鼠模型中评估了 SPA4 肽的生物学相关性。我们的结果表明，SPA4 肽在宿主外培养时不会与铜绿假单胞菌相互作用或杀死铜绿假单胞菌。SPA4 肽处理诱导细菌在免疫细胞的吞噬体中被摄取和定位。同时，SPA4 肽处理细胞的无细胞上清液中 TNF-α 的分泌量显著降低。在 TLR4 过表达的细胞中，TLR4 诱导的吞噬反应得以维持，但 TLR4 刺激的 TNF-α 水平降低。此外，我们的结果表明，SPA4 肽的治疗给药可降低铜绿假单胞菌感染小鼠的细菌负荷、炎症细胞因子和趋化因子、细胞内信号和乳酸水平，并减轻肺水肿和组织损伤。总之，我们的结果表明，SPA4 肽治疗可帮助控制铜绿假单胞菌肺部感染模型中的细菌负荷、炎症和组织损伤。
