Non-pathogenic commensal Escherichia coli bacteria can inhibit degranulation of mast cells.
BACKGROUND
The mast cell's (MC) ability to rapidly release presynthesized mediators allows it to play a critical role in the immune system's first-line response to pathogens. Although recent research has illuminated the role of MCs in bacterial infection, little is known about how non-pathogenic bacteria influence MC responses.


OBJECTIVE
To characterize the influence of non-pathogenic Escherichia coli bacteria on MCs.


RESULTS
High concentrations of live E. coli strongly down-modulated the degranulation of murine peritoneal MCs under all activator conditions. Bacteria did not induce MC degranulation by themselves, and staining of MCs showed they were still entirely viable. Dead bacteria and bacterial supernatant had no effect on MC degranulation. Ex vivo experiments confirmed that E. coli exposure down-modulates subsequently induced MC degranulation and that this effect lasts for up to a few days after exposure.


CONCLUSIONS
Our results show that high doses of non-pathogenic E. coli bacteria can function as a strong, direct inhibitor of MC degranulation. This suggests a possible basis for future antiallergic treatment or prophylaxis with commensal bacteria, i.e. probiotics.
Magerl
Markus
M
Department of Dermatology and Allergy, Charité- Universitätsmedizin, Berlin, Germany.
Lammel
Verena
V
Siebenhaar
Frank
F
Zuberbier
Torsten
T
Metz
Martin
M
Maurer
Marcus
M
D000818:Animals; D017209:Apoptosis; D000001:Calcimycin / Q000494:pharmacology; D015550:Cell Degranulation / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D002470:Cell Survival; D003609:Dactinomycin / Q000494:pharmacology; D004140:Dinitrophenols / Q000494:pharmacology; D004926:Escherichia coli / Q000472:pathogenicity; D005434:Flow Cytometry; D007073:Immunoglobulin E / Q000494:pharmacology; D008407:Mast Cells / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D010537:Peritoneum / Q000166:cytology; D012701:Serotonin / Q000032:analysis / Q000378:metabolism; D012709:Serum Albumin / Q000494:pharmacology; D014316:Tritium / Q000032:analysis
D004140:Dinitrophenols; D012709:Serum Albumin; C058064:dinitrophenyl-human serum albumin conjugate; D014316:Tritium; D003609:Dactinomycin; D012701:Serotonin; D007073:Immunoglobulin E; D000001:Calcimycin