Galleria mellonella hemocytes destruction after infection with Pseudomonas aeruginosa

The influence of infection with an entomopathogenic strain of Pseudomonas aeruginosa on Galleria mellonella hemocytes was investigated. Extensive bacteriaemia developed 18h after infection. This was correlated with significant changes in morphology, viability and the spreading ability of immunocompetent hemocytes, namely granulocytes and plasmatocytes. Since bacteriaemia developed, membrane blebbing, cytoplasm vacuolization, cell and organelle swelling, and chromatin condensation were observed among others. These features are typical for apoptotic and autophagal cell death. A gradually increasing level of procaspase and its activation as well as lack of DNA degradation were also detected. Propidium iodide and acridine orange staining indicated that hemocytes become dead ultimately. Infection of G. mellonella larvae with P. aeruginosa also caused significant changes in the arrangement of the actin cytoskeleton in the hemocytes, which might be correlated with their restricted spreading ability.