Department of Basic and Translational Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States.
Department of Family and Community Dentistry, Faculty of Dentistry, Chiang Mai University, Chiang Mai, Thailand.
Front Immunol. 2021 Jun 23;12:689410. doi: 10.3389/fimmu.2021.689410. eCollection 2021.
is a frequent cause of hospital-acquired wound infection and is difficult to treat because it forms biofilms and displays antibiotic resistance. Previous studies in mice demonstrated that mast cells (MCs) not only contribute to eradication but also promote wound healing an unknown mechanism. We recently reported that host defense peptides (HDPs) induce human MC degranulation Mas-related G protein-coupled receptor-X2 (MRGPRX2). Small molecule HDP mimetics have distinct advantages over HDPs because they are inexpensive to synthesize and display high stability, bioavailability, and low toxicity. Murepavadin is a lipidated HDP mimetic, (also known as POL7080), which displays antibacterial activity against a broad panel of multi-drug-resistant . We found that murepavadin induces Ca mobilization, degranulation, chemokine IL-8 and CCL3 production in a human MC line (LAD2 cells) endogenously expressing MRGPRX2. Murepavadin also caused degranulation in RBL-2H3 cells expressing MRGPRX2 but this response was significantly reduced in cells expressing missense variants within the receptor's ligand binding (G165E) or G protein coupling (V282M) domains. Compound 48/80 induced β-arrestin recruitment and promoted receptor internalization, which resulted in substantial decrease in the subsequent responsiveness to the MRGPRX2 agonist. By contrast, murepavadin did not cause β-arrestin-mediated MRGPRX2 regulation. Murepavadin induced degranulation in mouse peritoneal MCs MrgprB2 (ortholog of human MRGPRX2) and caused increased vascular permeability in wild-type mice but not in MrgprB2 mice. The data presented herein demonstrate that murepavadin activates human MCs MRGPRX2 and murine MCs MrgprB2 and that MRGPRX2 is resistant to β-arrestin-mediated receptor regulation. Thus, besides its direct activity against , murepavadin may contribute to bacterial clearance and promote wound healing by harnessing MC's immunomodulatory property the activation of MRGPRX2.
金黄色葡萄球菌是医院获得性伤口感染的常见原因，由于其形成生物膜并表现出抗生素耐药性，因此难以治疗。以前在小鼠中的研究表明，肥大细胞（MCs）不仅有助于消除金黄色葡萄球菌，还有助于伤口愈合，但具体机制尚不清楚。我们最近报道，宿主防御肽（HDPs）诱导人 MC 脱颗粒 通过 Mas 相关 G 蛋白偶联受体-X2（MRGPRX2）。小分子 HDP 模拟物具有优于 HDP 的明显优势，因为它们合成成本低廉，且具有高稳定性、生物利用度和低毒性。脂质化 HDP 模拟物 murepavadin（也称为 POL7080）对广泛的多药耐药菌具有抗菌活性。我们发现 murepavadin 诱导内源性表达 MRGPRX2 的人肥大细胞系（LAD2 细胞）中的钙动员、脱颗粒、趋化因子 IL-8 和 CCL3 的产生。murepavadin 还导致表达 MRGPRX2 的 RBL-2H3 细胞脱颗粒，但在表达受体配体结合（G165E）或 G 蛋白偶联（V282M）域内错义变体的细胞中，这种反应显著降低。化合物 48/80 诱导β-arrestin 募集并促进受体内化，从而导致对 MRGPRX2 激动剂的后续反应性显著降低。相比之下，murepavadin 不会引起 β-arrestin 介导的 MRGPRX2 调节。murepavadin 诱导小鼠腹膜肥大细胞脱颗粒 MrgprB2（人 MRGPRX2 的同源物）并导致野生型小鼠血管通透性增加，但 MrgprB2 小鼠则不会。本文所述的数据表明，murepavadin 激活人肥大细胞的 MRGPRX2 和鼠肥大细胞的 MrgprB2，并且 MRGPRX2 对 β-arrestin 介导的受体调节具有抗性。因此，除了对金黄色葡萄球菌的直接活性外，murepavadin 还可以通过利用 MC 的免疫调节特性（MRGPRX2 的激活）来清除细菌并促进伤口愈合。
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