Inflammation and apoptosis in Clostridium difficile enteritis is mediated by PGE2 up-regulation of Fas ligand.
OBJECTIVE
Clostridium difficile toxin A causes acute inflammation and fluid secretion in experimental animals and patients with C difficile infection. We previously reported that toxin A increased cyclooxygenase-2/prostaglandin E(2) (PGE(2)) expression and apoptosis in human colonocytes. Here, we assessed the role of secreted PGE(2) in inflammation and enterocyte apoptosis in toxin A enteritis.


METHODS
Effects of PGE(2) and PGE(2) blockade on toxin A-induced apoptosis of human colonocytes (NCM460) and of PGE(2) or toxin A on the Fas ligand (FasL) induction were analyzed by flow cytometry and Western blot. Functional activity of elevated FasL on colonocytes was assessed by coculture of colonocytes with Fas bearing Jurkat T cells. The involvement of PGE(2)-dependent Fas/FasL activation in toxin A enteritis was further assessed in either scid or FasL and Fas deficient mice.


RESULTS
Inhibition of cyclooxygenase-2 by NS-398 and of PGE(2) using a blocking antibody markedly attenuated apoptosis in colonocytes exposed to toxin A. Enhanced expression and release of FasL followed PGE(2) or toxin A exposure in vivo and in vitro and also was significantly attenuated by treatment with NS-398 and PGE(2) blocking antibody. PGE(2) acting through an EP1 receptor activated nuclear factor-kappaB, which induced transcription of FasL. Toxin A enteritis was accompanied by increased cellular infiltration, fluid secretion, and mucosal damage in control mice, but this response was markedly reduced in both Fas(-/-) and FasL(-/-) mice.


CONCLUSIONS
Toxin A enteritis involves release of PGE(2), which activates the Fas/FasL system, causing enterocyte apoptosis and inflammation.
Kim
Ho
H
Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA.
Rhee
Sang Hoon
SH
Pothoulakis
Charalabos
C
Lamont
J Thomas
JT
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001427:Bacterial Toxins; D002460:Cell Line; D016360:Clostridioides difficile; D018920:Coculture Techniques; D003106:Colon / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D051546:Cyclooxygenase 2 / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism*; D004751:Enteritis / Q000378:metabolism / Q000382:microbiology* / Q000473:pathology*; D004768:Enterotoxins / Q000502:physiology; D053222:Fas Ligand Protein / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007079:Ileitis / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D018345:Mice, Knockout; D016513:Mice, SCID; D016328:NF-kappa B / Q000378:metabolism; D018078:Receptors, Prostaglandin E / Q000378:metabolism; D058306:Receptors, Prostaglandin E, EP1 Subtype; D015854:Up-Regulation
D001427:Bacterial Toxins; D004768:Enterotoxins; D053222:Fas Ligand Protein; D016328:NF-kappa B; C545635:PTGER1 protein, human; C545636:Ptger1 protein, mouse; D018078:Receptors, Prostaglandin E; D058306:Receptors, Prostaglandin E, EP1 Subtype; C041348:tcdA protein, Clostridium difficile; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2; D015232:Dinoprostone