Rincon Jaimar, Viera Ninoska T, Romero Maritza J, Mosquera Jesus A
Instituto de Investigaciones Clinicas Dr. Americo Negrette, Facultad de Medicina, Universidad del Zulia, Maracaibo, Venezuela.
Nephrol Dial Transplant. 2003 Jun;18(6):1072-8. doi: 10.1093/ndt/gfg109.
Previous reports have demonstrated the presence of streptococcal erythrogenic toxin type B (ETB) as well as proliferation and expression of adhesion molecules along with leukocyte infiltrations in biopsies from patients with acute post-streptococcal glomerulonephritis (APSGN). The purpose of the present study was to correlate infiltrative and proliferative events with interactions between ETB or its precursor (ETBP) and intrinsic mesangial cells.
Rat mesangial cells were cultured with ETB or ETBP (50 micro g/ml) while measuring production of monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-2 (MIP-2) and while examining proliferation and expression of intercellular adhesion molecule-1 (ICAM-1). After 24, 48 and 96 h of incubation, MCP-1 and MIP-2 in culture supernatants were assessed by enzyme-linked immunosorbent assay (ELISA). Cells were assessed for proliferation by incorporation of radioactive thymidine and expression of ICAM-1 was measured by indirect immunofluorescence and by cellular ELISA.
Compared with controls, treatment with either ETBP or ETB significantly increased MCP-1 and MIP-2 levels in mesangial cell cultures. Mesangial cells also showed elevated proliferation at 96 h of culture when treated with streptococcal proteins. Although production of MCP-1 and MIP-2 was not correlated with proliferation, treatment with ETBP resulted in a significant correlation between MCP-1 production and proliferation. Immunofluorescence studies revealed an increased expression of ICAM-1 in ETBP/ETB-treated mesangial cells. In addition, cellular ELISA studies showed increased absorbance in cultures treated with ETBP/ETB. Finally, low serum concentrations in the culture medium potentiated the stimulatory effect of ETB on MCP-1 production.
Our findings, by demonstrating a role for cationic streptococcal ETB or ETBP in the induction of chemotactic molecules as well as the proliferation and expression of adhesion molecules, delineate an additional possible pathway for the pathogenesis of APSGN.
既往报道已证实在急性链球菌感染后肾小球肾炎（APSGN）患者的活检组织中存在B型链球菌致热外毒素（ETB），以及黏附分子的增殖和表达，同时伴有白细胞浸润。本研究的目的是将浸润和增殖事件与ETB或其前体（ETBP）与系膜固有细胞之间的相互作用联系起来。
用ETB或ETBP（50μg/ml）培养大鼠系膜细胞，同时检测单核细胞趋化蛋白-1（MCP-1）和巨噬细胞炎性蛋白-2（MIP-2）的产生，并检测细胞间黏附分子-1（ICAM-1）的增殖和表达。孵育24、48和96小时后，通过酶联免疫吸附测定（ELISA）评估培养上清液中的MCP-1和MIP-2。通过放射性胸腺嘧啶掺入评估细胞增殖，通过间接免疫荧光和细胞ELISA测定ICAM-1的表达。
与对照组相比，用ETBP或ETB处理显著增加了系膜细胞培养物中MCP-1和MIP-2的水平。用链球菌蛋白处理时，系膜细胞在培养96小时时也显示出增殖增加。虽然MCP-1和MIP-2的产生与增殖无关，但用ETBP处理导致MCP-1产生与增殖之间存在显著相关性。免疫荧光研究显示，经ETBP/ETB处理的系膜细胞中ICAM-1的表达增加。此外，细胞ELISA研究显示，经ETBP/ETB处理的培养物中吸光度增加。最后，培养基中低血清浓度增强了ETB对MCP-1产生的刺激作用。
我们的研究结果表明，阳离子链球菌ETB或ETBP在趋化分子的诱导以及黏附分子的增殖和表达中起作用，描绘了APSGN发病机制的另一条可能途径。
