Characterization of HeLa cell vacuoles induced by Helicobacter pylori broth culture supernatant.
Helicobacter pylori broth culture supernatants induce eukaryotic cell vacuolation in vitro, a phenomenon that has been attributed to cytotoxic activity. We sought to characterize further the vacuolation of HeLa cells that occurs in response to H pylori culture supernatant. Nascent vacuoles were detectable by electron microscopy after 90 minutes of incubation with H pylori supernatant and were not associated with any identifiable organelle. After 6 days of incubation with H pylori supernatant, vacuoles were membrane-bound structures filled with electron-dense debris, which resembled secondary lysosomes. Acid phosphatase activity was detected within the vacuoles. The vacuoles induced by H pylori supernatant were then compared with vacuoles induced by trimethylamine, a weak base known to induce lysosomal swelling. Neutral red dye rapidly entered the vacuoles induced by either H pylori supernatant or trimethylamine, and both types of vacuoles were reversible. Compared with trimethylamine-induced vacuoles, the vacuoles induced by H pylori supernatant were larger and typically lacked a limiting membrane. In the early stages of formation, vacuoles induced by trimethylamine were labeled by lucifer yellow, a pinocytotic marker, whereas H pylori cytotoxin-induced vacuoles were not. These data suggest that trimethylamine-induced vacuoles arise directly from endocytic compartments, whereas H pylori cytotoxin induces vacuole formation via an autophagic mechanism.
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Infectious Diseases Section, Department of Veterans Affairs Medical Center, Nashville, TN.
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Blaser
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D000135:Acid Phosphatase / Q000378:metabolism; D002478:Cells, Cultured; D003603:Cytotoxins / Q000378:metabolism / Q000502:physiology*; D005456:Fluorescent Dyes; D006367:HeLa Cells / Q000378:metabolism / Q000648:ultrastructure*; D016480:Helicobacter pylori / Q000378:metabolism*; D006801:Humans; D007546:Isoquinolines; D008744:Methylamines / Q000494:pharmacology; D009499:Neutral Red / Q000493:pharmacokinetics; D013194:Staining and Labeling; D014617:Vacuoles / Q000378:metabolism / Q000648:ultrastructure*
D003603:Cytotoxins; D005456:Fluorescent Dyes; D007546:Isoquinolines; D008744:Methylamines; D009499:Neutral Red; C017475:lucifer yellow; D000135:Acid Phosphatase; C023336:trimethylamine