Differential activation of eosinophils by 'probiotic' Bifidobacterium bifidum and 'pathogenic' Clostridium difficile.
BACKGROUND
Recent studies suggest that probiotics alleviate pathophysiological processes of allergic diseases and inflammatory bowel diseases, whereas 'non-probiotic' microflora has negative effects. However, the underlying mechanisms are not well known, especially in relation to eosinophils, the major effector cells of these inflammatory diseases.


OBJECTIVE
To investigate the effects of probiotic Bifidobacterium bifidum (BB) on human eosinophil functions compared with pathogenic Clostridium difficile (CD).


METHODS
Peripheral human eosinophils were cultured with heat-killed BB or CD. FISH-labeled CD and BB were incubated with eosinophils visualized by confocal laser scanning microscopy. Superoxide generation and degranulation of eosinophils were measured with the cytochrome c reduction method and the eosinophil-derived neurotoxin (EDN) release assay, respectively.


RESULTS
Confocal microscopy revealed that Cy3-labeled CD and BB were apparently ingested by eosinophils. Both bacteria induced minimal superoxide generation. However, CD elicited significantly higher EDN release than BB. GM-CSF significantly enhanced EDN release by CD but not by BB. Bacterial-induced EDN release was calcium dependent.


CONCLUSIONS
The beneficial effect of probiotic BB might be explained, at least in part, by its ability to decrease EDN release from eosinophils compared with 'pathogenic' CD.
Institute for Clinical Research, Mie University Hospital, Tsu, Japan.
Koa
K
Hosoki
Akiko
A
Nakamura
Mizuho
M
Nagao
Yukiko
Y
Hiraguchi
Reiko
R
Tokuda
Hideo
H
Wada
Tsutomu
T
Nobori
Takao
T
Fujisawa
D001644:Bifidobacterium / Q000276:immunology*; D015550:Cell Degranulation / Q000187:drug effects / Q000276:immunology; D016360:Clostridioides difficile / Q000276:immunology*; D004533:Egtazic Acid / Q000494:pharmacology; D047208:Eosinophil-Derived Neurotoxin / Q000378:metabolism; D004804:Eosinophils / Q000276:immunology* / Q000378:metabolism; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D055633:Immune System Phenomena / Q000276:immunology*; D037342:Pertussis Toxin / Q000494:pharmacology; D010587:Phagocytosis / Q000276:immunology; D019936:Probiotics; D013481:Superoxides / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D014409:Tumor Necrosis Factor-alpha; D013481:Superoxides; D004533:Egtazic Acid; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D037342:Pertussis Toxin; D047208:Eosinophil-Derived Neurotoxin