inositol-1-4-5-trisphosphate and Escherichia-coli-Infections

Human enteropathogenic Escherichia coli infection of epithelial cells is characterized by attaching and effacing adhesion. To determine if signal transduction responses are involved in this adhesion phenotype, levels of inositol 1,4,5-triphosphate and cytosolic free calcium were measured in tissue culture cells infected with enteropathogenic E. coli strain E2348 (serotype O127:H6).. Inositol triphosphate levels were measured by using a commercial binding assay, and intracellular calcium levels were determined by spectrofluorometry.. Elevated levels of both inositol triphosphate (182% +/- 52%; P < 0.05) and intracellular calcium (125% +/- 40%, mean +/- SE; P < 0.05) were seen after infection of HEp-2 cells with strain E2348. In contrast, inositol triphosphate and intracellular calcium levels were not elevated in HEp-2 cells infected with six E. coli strains that did not cause attaching and effacing lesions. Subcellular calcium localization using oxalate precipitation and electron microscopy showed calcium accumulation within the terminal web subjacent to regions of attaching and effacing adhesion. Depleting external calcium did not eliminate formation of attaching and effacing lesions, whereas treatment of HEp-2 cells with an intracellular calcium chelator prevented attaching and effacing lesions.. Enteropathogenic E. coli infection elevates both inositol triphosphate and intracellular calcium levels in cultured epithelial cells.

Topics: Bacterial Adhesion; Calcium; Cell Line; Egtazic Acid; Epithelial Cells; Epithelium; Escherichia coli; Escherichia coli Infections; Humans; In Vitro Techniques; Inositol 1,4,5-Trisphosphate; Microscopy, Electron; Oxalates; Phenotype; Phosphatidylinositol 4,5-Diphosphate; Phosphatidylinositol Phosphates; Signal Transduction; Spectrometry, Fluorescence

Inositol trisphosphate-dependent Ca2+ release was measured in saponin-permeabilized hepatocytes isolated from acutely (2 mg/100 g body wt iv) or chronically (0.1 mg X 100 g body wt-1 X 24 h-1 for 30 h) endotoxin-treated (ET, Escherichia coli) rats or from animals rendered septic by cecal ligation and puncture. A decrease of this parameter was observed in acutely ET-treated rats (52%, P less than 0.01) and after 30 h of continuous ET infusion (33%, P less than 0.01). Sepsis was associated with an elevated Ca2+ release (34%, P less than 0.01) as compared with the sham-operated animals. We conclude that during endotoxicosis and sepsis alterations of intracellular Ca homeostasis take place, reaching sites beyond the level of the plasma membrane. Such alterations could account in part for metabolic and functional changes associated with these pathologic states. In addition, ET treatment provides the first known intervention resulting in the modulation of inositol trisphosphate-dependent Ca2+ release.

Topics: Animals; Calcium; Cell Membrane Permeability; Endotoxins; Escherichia coli; Escherichia coli Infections; Inositol 1,4,5-Trisphosphate; Inositol Phosphates; Liver; Male; Rats; Rats, Inbred Strains; Sugar Phosphates