Role of immune serum in the killing of Helicobacter pylori by macrophages.
BACKGROUND
Helicobacter pylori infection can lead to the development of gastritis, peptic ulcers and gastric cancer, which makes this bacterium an important concern for human health. Despite evoking a strong immune response in the host, H. pylori persists, requiring complex antibiotic therapy for eradication. Here we have studied the impact of a patient's immune serum on H. pylori in relation to macrophage uptake, phagosome maturation, and bacterial killing.


METHODS
Primary human macrophages were infected in vitro with both immune serum-treated and control H. pylori. The ability of primary human macrophages to kill H. pylori was characterized at various time points after infection. H. pylori phagosome maturation was analyzed by confocal immune fluorescence microscopy using markers specific for H. pylori, early endosomes (EEA1), late endosomes (CD63) and lysosomes (LAMP-1).


RESULTS
Immune serum enhanced H. pylori uptake into macrophages when compared to control bacteria. However, a sufficient inoculum remained for recovery of viable H. pylori from macrophages, at 8 hours after infection, for both the serum-treated and control groups. Both serum-treated and control H. pylori phagosomes acquired EEA1 (15 minutes), CD63 and LAMP-1 (30 minutes). These markers were then retained for the rest of an 8 hour time course.


CONCLUSIONS
While immune sera appeared to have a slight positive effect on bacterial uptake, both serum-treated and control H. pylori were not eliminated by macrophages. Furthermore, the same disruptions to phagosome maturation were observed for both serum-treated and control H. pylori. We conclude that to eliminate H. pylori, a strategy is required to restore the normal process of phagosome maturation and enable effective macrophage killing of H. pylori, following a host immune response.
Keep
Stacey
S
University of South Australia, Adelaide, Australia.
Borlace
Glenn
G
Butler
Ross
R
Brooks
Doug
D
D000328:Adult; D015703:Antigens, CD / Q000032:analysis; D002478:Cells, Cultured; D015169:Colony Count, Microbial; D011992:Endosomes / Q000737:chemistry / Q000382:microbiology; D016480:Helicobacter pylori / Q000276:immunology* / Q000472:pathogenicity*; D006801:Humans; D007106:Immune Sera / Q000276:immunology*; D051907:Lysosomal Membrane Proteins / Q000032:analysis; D008247:Lysosomes / Q000737:chemistry / Q000382:microbiology; D008264:Macrophages / Q000276:immunology*; D050296:Microbial Viability; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D010588:Phagosomes / Q000737:chemistry / Q000382:microbiology; D010980:Platelet Membrane Glycoproteins / Q000032:analysis; D060149:Tetraspanin 30; D013997:Time Factors; D033921:Vesicular Transport Proteins / Q000032:analysis; D052118:Lysosomal-Associated Membrane Protein 1
D015703:Antigens, CD; D007106:Immune Sera; D051907:Lysosomal Membrane Proteins; D010980:Platelet Membrane Glycoproteins; D060149:Tetraspanin 30; D033921:Vesicular Transport Proteins; C554586:CD63 protein, human; C489116:LAMP1 protein, human; D052118:Lysosomal-Associated Membrane Protein 1; C093846:early endosome antigen 1