College of Life Sciences and Medicine, Zhejiang Sci-Tech University, 310018, China.
Huzhou Baijiayu Biotech Co., Ltd., 313000 Huzhou, China.
Mol Immunol. 2021 May;133:14-22. doi: 10.1016/j.molimm.2021.02.001. Epub 2021 Feb 18.
The polymeric immunoglobulin receptor (pIgR) is an important molecule in the mucosal immunity of teleosts. Previous studies have shown that pIgR can bind and transport polymeric immunoglobulins (pIgs), but few studies have focused on the binding of teleost pIgR to bacteria. In this study, we identified a gene encoding pIgR in largemouth bass (Micropterus salmoides). The pIgR gene contained two Ig-like domains (ILDs), which were homologous to ILD1 and ILD5 of mammalian pIgR. Our results showed that largemouth bass pIgR-ILD could combine with IgM. Moreover, we also found that largemouth bass pIgR-ILD could bind to Aeromonas hydrophila and Micrococcus luteus. Further analysis showed that largemouth bass pIgR-ILD could also combine with lipopolysaccharide (LPS), peptidoglycan (PGN) and various saccharides, and reduced binding to bacteria was observed with LPS and PGN treatment, indicating that largemouth bass pIgR could bind to bacteria to prevent infection and that saccharide binding is an important interaction mechanism between pIgR and bacteria. These results collectively demonstrated that largemouth bass pIgR not only combines with IgM but also binds to bacteria by various saccharides.
多聚免疫球蛋白受体（pIgR）是鱼类黏膜免疫中的一个重要分子。先前的研究表明，pIgR 可以结合并转运多聚免疫球蛋白（pIgs），但很少有研究关注鱼类 pIgR 与细菌的结合。本研究在大口黑鲈（Micropterus salmoides）中鉴定到一个编码 pIgR 的基因。该 pIgR 基因包含两个免疫球蛋白样结构域（ILDs），与哺乳动物 pIgR 的 ILD1 和 ILD5 同源。我们的结果表明，大口黑鲈 pIgR-ILD 可以与 IgM 结合。此外，我们还发现大口黑鲈 pIgR-ILD 可以与嗜水气单胞菌和藤黄微球菌结合。进一步分析表明，大口黑鲈 pIgR-ILD 还可以与脂多糖（LPS）、肽聚糖（PGN）和各种糖结合，并且 LPS 和 PGN 处理后观察到与细菌的结合减少，表明大口黑鲈 pIgR 可以通过结合糖来结合细菌以防止感染，而糖结合是 pIgR 与细菌相互作用的重要机制。这些结果共同表明，大口黑鲈 pIgR 不仅与 IgM 结合，还可以通过各种糖结合细菌。
