Molecular analyses on Streptococcus pyogenes adherence to and invasion of pharyngeal epithelial cells

本研究的结果表明：1。化脓性链球菌可以以相当高的频率内化为人咽上皮细胞。此外，化脓性链球菌透明质酸的存在降低了其入侵效率。所有的化脓性葡萄球菌菌株都含有fbp54基因，该基因编码纤维连接蛋白结合蛋白fbp54，是一种很有希望预防化脓性葡萄球菌感染的疫苗。3 .化脓性葡萄球菌在上皮细胞内的内化是诱导细胞凋亡的必要和充分条件，细胞凋亡是由线粒体功能障碍启动的，并且化脓性葡萄球菌诱导细胞凋亡的机制明显不同于其他细胞内侵袭性细菌如志贺菌和沙门氏菌诱导的细胞凋亡。蛋白Fba促进化脓性链球菌进入人上皮细胞。该蛋白具有3或4个富含脯氨酸的重复结构域，与金黄色葡萄球菌的纤维连接蛋白结合蛋白FnBPA具有高度同源性。fba基因存在于化脓链球菌的M型1、2、4、22、28和49中，在Mga调控子的控制下转录。给予超级抗原保护小鼠免受细胞内细菌（如李斯特菌）的感染，这依赖于CD4^+ T细胞存在时李斯特菌特异性CTL活性的增强，并且超级抗原在免疫细胞内病原体时表现出佐剂活性。Lbp蛋白具有层粘连蛋白结合活性，参与咽部上皮细胞的粘附。

The results obtained by this study suggest that1. Streptococcus pyogenes can be internalized into human pharyngeal epithelial cells with considerably high frequencies. Furthermore, the presence of hyaluronic acid of S. pyogenes decreases the invasion efficiency.2. All the S. pyogenes strains possess the fbp54 gene encoding fibronectin-binding protein FBP54, which is a promising vaccine for the prevention of S. pyogenes infections.3. The internalization of S. pyogenes in epithelial cells is necessary and sufficient for the induction of apoptosis, which is initiated by mitochondrial dysfunction, and the mechanism of S. pyogenes-induced apoptosis is clearly different from that induced by other intracellular invasive bacteria, e.g. Shigella and Salmonella species.4. Protein Fba promotes S. pyogenes entry into human epithelial cells. This protein possesses three or four proline-rich repeat domains and exhibits a high homology to FnBPA, the fibronectin-binding protein of Staphylocaccus aureus. The fba gene is found in M types 1, 2, 4, 22, 28, and 49 of S. pyogenes, and is transcribed under the control of the Mga regulator.5. Administration of superantigens protect mice from infection with intracellular bacteria such as Listeria, which is dependent on the enhanced Listeria-specific CTL activity in the presence of CD4^+ T cells, and superantigens exhibit adjuvant activity in the immunization against intracellular pathogens.6. Protein Lbp possesses laminin-binding activity and is involved in adhesion to pharyngeal epithelial cell.