Bergman M J, Guerrant R L, Murad F, Richardson S H, Weaver D, Mandell G L
J Clin Invest. 1978 Feb;61(2):227-34. doi: 10.1172/JCI108931.
Enterotoxigenic Escherichia coli are associated with noninflammatory diarrhea and stimulate adenylate cyclase activity of mammalian cells, thereby increasing intracellular cyclic adenosine 3',5'-monophosphate (cyclic AMP). Increased concentrations of cyclic AMP in polymorphonuclear neutrophils (PMN) inhibit phagocytosis, candidacidal activity, granule discharge, and chemotactic responsiveness. We examined the effect of enterotoxin on the interaction of human PMN with E. coli. Enterotoxigenic and nonenterotoxigenic strains, including serotypes of E. coli identical except for the presence or absence of the plasmid coding for enterotoxin production, were utilized. Enterotoxigenic and nonenterotoxigenic E. coli, tumbled with PMN, were phagocytized and killed (>97%) equally well, and these strains stimulated PMN hexose monophosphate shunt activity equivalently.However, a chemotaxis assay under agarose demonstrated that filtrates of 10 enterotoxigenic strains were less chemotactic for PMN by 15+/-2% total migration or 46+/-1% directed migration, when compared with 6 non-enterotoxigenic strains (P < 0.001). Inactivation of the enterotoxin by heat (65 degrees C for 30 min) or antibodies formed to E. coli enterotoxin eliminated the inhibitory effect of the enterotoxic filtrates for PMN chemotaxis. Addition of purified E. coli enterotoxin directly to the PMN decreased chemotaxis to E. coli filtrates by 32+/-2% (P < 0.001). These data suggest that the effect was due to the heat-labile enterotoxin. The phosphodiesterase inhibitor, 1-methyl-3-isobutylxanthine (0.1 mM), which potentiates effects due to an increase in intracellular cyclic AMP, further decreased total PMN migration (random plus directed) toward enterotoxic filtrates to 46% of that to nonenterotoxic filtrates (P < 0.001). Addition of cholera toxin (1 mug/ml), which is similar to E. coli enterotoxin, to the PMN inhibited total migration toward nonenterotoxic filtrates by 16+/-2% (P < 0.001). Exogenous dibutyryl cyclic AMP (2 mM) inhibited total PMN migration toward E. coli filtrates by 32% (P < 0.001). PMN intracellular cyclic AMP levels increased by 220% after 2 h of incubation with purified E. coli enterotoxin. The decreased chemotactic attractiveness of enterotoxic E. coli filtrates appears to be related to the ability of enterotoxin to increase cyclic AMP in PMN. Enterotoxin production by E. coli may be advantageous to the microbe by decreasing its chemotactic appeal for PMN.
产肠毒素大肠杆菌与非炎性腹泻相关，并刺激哺乳动物细胞的腺苷酸环化酶活性，从而增加细胞内环磷酸腺苷（cAMP）的浓度。多形核中性粒细胞（PMN）中cAMP浓度的增加会抑制吞噬作用、杀念珠菌活性、颗粒释放和趋化反应性。我们研究了肠毒素对人PMN与大肠杆菌相互作用的影响。使用了产肠毒素和非产肠毒素菌株，包括除了编码产肠毒素的质粒存在与否外其他都相同的大肠杆菌血清型。产肠毒素和非产肠毒素的大肠杆菌与PMN一起翻滚，被吞噬和杀死的情况（>97%）同样良好，并且这些菌株同等程度地刺激PMN的磷酸己糖旁路活性。然而，琼脂糖下的趋化试验表明，与6株非产肠毒素菌株相比，10株产肠毒素菌株的滤液对PMN的趋化作用降低了15±2%的总迁移率或46±1%的定向迁移率（P<0.001）。通过加热（65℃30分钟）或针对大肠杆菌肠毒素形成的抗体使肠毒素失活，消除了产肠毒素滤液对PMN趋化作用的抑制效果。将纯化的大肠杆菌肠毒素直接添加到PMN中，使对大肠杆菌滤液的趋化作用降低了32±2%（P<0.001）。这些数据表明该作用是由于不耐热肠毒素。磷酸二酯酶抑制剂1-甲基-3-异丁基黄嘌呤（0.1mM），它由于细胞内cAMP增加而增强作用，进一步使PMN向产肠毒素滤液的总迁移率（随机加定向）降低至向非产肠毒素滤液迁移率的46%（P<0.001）。向PMN中添加与大肠杆菌肠毒素相似的霍乱毒素（1μg/ml），使向非产肠毒素滤液的总迁移率降低了16±2%（P<0.001）。外源性二丁酰环磷腺苷（2mM）使PMN向大肠杆菌滤液的总迁移率降低了32%（P<0.001）。与纯化的大肠杆菌肠毒素孵育2小时后，PMN细胞内cAMP水平增加了220%。产肠毒素大肠杆菌滤液趋化吸引力的降低似乎与肠毒素增加PMN中cAMP的能力有关。大肠杆菌产生肠毒素可能通过降低其对PMN的趋化吸引力而对微生物有利。
