Effects of toxin A from Clostridium difficile on mast cell activation and survival.
Toxins A and B from Clostridium difficile are the main cause of antibiotic-associated diarrhea and pseudomembranous colitis. They cause fluid accumulation, necrosis, and a strong inflammatory response when inoculated in intestinal loops. Since mast cells are a rich source of inflammatory mediators, abundant in the gut, and known to be involved in C. difficile-induced enteritis, we studied the in vitro effect of toxin A on isolated mast cells. Normal rats sensitized by infection with Nippostrongilus brasiliensis were used to isolate peritoneal mast cells (PMC). PMC from naive rats were stimulated with calcium ionophore A23187 as a model of antigen-independent activation, and PMC from sensitized rats were stimulated with N. brasiliensis antigens to study immunoglobulin E-dependent mast cell activation. After 4 h, toxin A did not induce release of nitric oxide or histamine in naive PMC. However, 10 ng of toxin per ml caused a significant release of tumor necrosis factor alpha (TNF-alpha). In contrast, 1 microg of toxin per ml inhibited antigen or A23187-induced histamine release by PMC. Toxin A at 1 microg/ml for 4 h caused disruption of actin which aggregated in the cytoplasm and around the nucleus. After 24 h, chromatin condensation, cytoplasmic blebbing, and apoptotic-like vesicles were observed; DNA fragmentation was documented also. These results suggest that mast cells may participate in the initial inflammatory response to C. difficile infection by releasing TNF-alpha upon interaction with toxin A. However, longer exposure to toxin A affects the release of inflammatory mediators, perhaps because of the alteration of the cytoskeleton and induction of apoptosis. The impaired functions and survival of mast cells by C. difficile toxin A could hamper the capacity of these cells to counteract the infection, thus prolonging the pathogenic effects of C. difficile toxins.
Calderón
G M
GM
UIMEIP, Hospital de Pediatría, CMN Siglo XXI, IMSS, México City.
Torres-López
J
J
Lin
T J
TJ
Chavez
B
B
Hernández
M
M
Muñoz
O
O
Befus
A D
AD
Enciso
J A
JA
D000818:Animals; D017209:Apoptosis; D001427:Bacterial Toxins / Q000494:pharmacology*; D002470:Cell Survival; D016360:Clostridioides difficile; D003599:Cytoskeleton / Q000187:drug effects; D053938:DNA Fragmentation; D004305:Dose-Response Relationship, Drug; D004768:Enterotoxins / Q000494:pharmacology*; D006636:Histamine Release; D007073:Immunoglobulin E / Q000494:pharmacology; D008297:Male; D008407:Mast Cells / Q000187:drug effects* / Q000648:ultrastructure; D009569:Nitric Oxide / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D001427:Bacterial Toxins; D004768:Enterotoxins; D014409:Tumor Necrosis Factor-alpha; C041348:tcdA protein, Clostridium difficile; D009569:Nitric Oxide; D007073:Immunoglobulin E