Searching the point of no return in Helicobacter pylori life: necrosis and/or programmed death?

Aims: Ultrastructural and molecular studies to support the hypothesis of pr ogrammed cell death in Helicobacter pylori were conducted. Methods and Results: Evidence of programmed death in H. pylori is provided through electron microscopic detection and cytochemical labelling of electr ondense bodies (EDB), containing packaged DNA in coccoid cells, resembling micronuclei of apoptotic eukaryotic cells. This morphological evidence is a lso supported by DNA cleavage in homogeneous fragments of about 100 base pa irs. Programmed cell death was observed in H. pylori cultures at 37 degrees C, with a maximum of 37.5% of EDB coccoid cells after 7 days. The non-permi ssive temperature of 4 degreesC anticipated this process, with 40% of EDB c occoid forms within 3 days, and it remained substantially unaffected during the observation time of 14 days. Conclusion: In these experiments, deprivation of nutrients and a non-permis sive temperature acted as a powerful trigger for programmed cell death. Significance and Impact of the Study: Helicobacter pylori bacterial populat ions, under stressing stimuli, can respond with programmed cell suicide as a means of species preservation.