Basic studies on the biological functions and possibilities of clinical applications of an intestinal IgG Fc binding site.

肠道 IgG Fc 结合位点的生物学功能和临床应用可能性的基础研究。

• 批准号: 04670400
• 负责人: HAMADA Yoshiki
• 金额: $ 1.34万
• 依托单位: KITASATO INSTITUTE
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1992
• 资助国家: 日本
• 起止时间: 1992 至 1993
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04670400/
• 关键词: IgG Fc binding site; mucus

Intestinal mucus is very important in protecting the intestinal mucosa against various harmful antigens, however the mechanisms involved are incompletely defined. Recently, we identified a binding site for the Fc region of IgG(FcIBS) associated with goblet cell mucin in human intestine. We documented that FcIBS could bind antibodies-bacterial complexes. This time we investigated the following biological functions of FcIBS and tried to establish recombinant FcIBS.1) Establishment of recombinant FcIBS : Human colonic epithelium were separated from colonic mucosa. Fraction of mRNA was gained from poly(A) fraction of the colonic epithelia extract. This fraction containing mRNA was injected into the ovum of Xenopus leavis and translated into FcIBS protein. However we could not make cDNA of FcIBS.2) Effect of FcIBS on growth of bacteria : Culture of RDEC-1 both in the presence of anti-RDEC-1 IgG and 10K supernatant of colonic homogenate resulted in a significant reduction of colony number in growth of bacteria. Culture of human pathogenic E.Coli(0111) or Salmonella typhimurium(04) both in the presence of anti-bacterial IgG and 10K supernatant of colonic homogenate has resemble results to that of RDEC-1. These results suggested that FcIBS may play a role in preventing bacteria from attaching to the epithelial surface of the intestine. 3) Inhibition of complement binding by FcIBS : When anti-sheep red blood cells (SRBC) IgG were pre-incubated with affinity-purified FcIBS, the ability of the antibodies to lyse SRBC in the presence of complement was inhibited significantly. These results suggested that FcIBS may interfere the activation of complement and the tissue injury associated with immune complex formation on the epithelium.

肠粘液在保护肠道粘膜免受各种有害抗原的侵害中起着非常重要的作用，但其作用机制尚不完全清楚。最近，我们在人的肠道中发现了与杯状细胞粘蛋白相关的免疫球蛋白Fc区(FCIBS)的结合部位。我们发现FCIBS可以结合抗体-细菌复合体。本研究对FCIBS的以下生物学功能进行了研究，并尝试建立了重组FcIBS。1)重组FCIBS的建立：从结肠粘膜中分离出人结肠上皮细胞。从结肠上皮细胞提取液中提取多聚(A)组分，提取各组分的mRNA。将这一含有mRNA的片段注射到非洲爪哇的卵子中，并转化为FCIBS蛋白。2)FCIBS对细菌生长的影响：RDEC-1在加入抗RDEC-1抗体和10K结肠匀浆上清液的同时培养，细菌生长的菌落数明显减少。人致病性大肠埃希菌(0111)和鼠伤寒沙门氏菌(04)在抗菌素抗体和10K结肠匀浆上清液中的培养结果与RDEC-1相似。这些结果提示，FCIBS可能具有防止细菌附着在肠道上皮表面的作用。3)FCIBS对补体结合的抑制作用：当抗绵羊红细胞(SRBC)抗体与亲和纯化的FCIBS预先孵育时，抗体在补体存在下裂解SRBC的能力被显著抑制。这些结果提示，FCIBS可能干扰补体的激活和与上皮免疫复合物形成相关的组织损伤。

项目成果

Y.HAMADA: "Tumor necrosis factor-α decrases expression of the interstinal IgG Fc binding Site by HT29-N2 Cells" Immunology. 74. 298-303 (1991)

Y.HAMADA：“肿瘤坏死因子-α 降低 HT29-N2 细胞间的 IgG Fc 结合位点的表达”《免疫学》74. 298-303 (1991)。