Paneth cell cryptdins act in vitro as apical paracrine regulators of the innate inflammatory response.
Intestinal-specific antimicrobial alpha-defensins, termed cryptdins, are secreted into the intestinal lumen by mouse Paneth cells in response to microbial pathogens. Cryptdins kill microbes by forming pores in their limiting membranes. The cryptdin isoforms 2 and 3 also can form anion-conductive pores in eukaryotic cell membranes, thus affecting cell physiology. Here, we find that when applied to apical membranes of the human intestinal cell line T84, cryptdin 3 (Cr3) induces secretion of the proinflammatory cytokine interleukin 8 (IL-8) in a dose-dependent manner. The induction of IL-8 secretion is specific to the cryptdins that form channels in mammalian cell membranes because cryptdin 4, which does not form pores in T84 cells, does not induce IL-8 secretion. Cr3 induces inflammatory cytokine secretion by activating NF-kappaB and p38 mitogen-activated protein kinase in a Ca2+-dependent manner, but influx by extra-cellular Ca2+ is not involved. Unlike other known inflammatory agonists, signal transduction by Cr3 occurs slowly, suggesting a novel mechanism of action. These results show that selective cryptdins may amplify their roles in innate immunity by acting as novel paracrine agonists to coordinate an inflammatory response with the antimicrobial secretions of Paneth cells.
Lin
Patricia W
PW
Gastrointestinal Cell Biology Department, Combined Program in Pediatric Gastroenterology and Nutrition, Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
Simon
Peter O
PO
Gewirtz
Andrew T
AT
Neish
Andrew S
AS
Ouellette
Andre J
AJ
Madara
James L
JL
Lencer
Wayne I
WI
D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins; D002460:Cell Line; D045744:Cell Line, Tumor; D016207:Cytokines / Q000096:biosynthesis / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D015151:Immunoblotting; D007249:Inflammation; D016209:Interleukin-8 / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008562:Membrane Glycoproteins / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D019879:Paneth Cells / Q000378:metabolism*; D010766:Phosphorylation; D020033:Protein Isoforms; D011498:Protein Precursors / Q000737:chemistry*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D050857:Synaptotagmins; D013997:Time Factors; D014158:Transcription, Genetic; D048051:p38 Mitogen-Activated Protein Kinases
D002135:Calcium-Binding Proteins; D016207:Cytokines; D016209:Interleukin-8; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D011498:Protein Precursors; C059569:cryptdin; D050857:Synaptotagmins; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D002118:Calcium