Increased substance P responses in dorsal root ganglia and intestinal macrophages during Clostridium difficile toxin A enteritis in rats.
Previously we reported that pretreatment of rats with the substance P (SP) antagonist CP-96,345 inhibits the enterotoxic responses following administration of toxin A from Clostridium difficile into ileal loops, indicating that SP participates in the intestinal responses to this toxin. We now report that injection of toxin A into rat ileum causes a rapid increase in SP content in lumbar dorsal root ganglia (DRG) and mucosal scrapings 30-60 min after toxin A administration. Toxin A-mediated fluid secretion, mannitol permeability, and ileal histologic damage is significantly increased only after 2 hr. Toxin A also causes an increase in the abundance of SP mRNA in lumbar DRG and ileal mucosa as measured by reverse transcription-PCR. Lamina propria macrophages (LPMs) obtained from toxin A-injected loops release greater amounts of tumor necrosis factor alpha (TNFalpha) and SP as compared with LPMs isolated from buffer-injected loops (P < 0.01). Pretreatment of rats with the SP antagonist CP-96,345 inhibits toxin A-mediated TNFalpha release from isolated LPMs, whereas an inactive enantiomer (CP-96,344) of the SP antagonist has no effect. LPMs obtained from toxin A-injected ileal loops incubated in vitro with SP (10(-8) to 10(-9) M) show enhanced TNFalpha secretion, whereas LPMs isolated from buffer-injected loops do not respond to SP. In addition, LPMs obtained from toxin A-injected ileal loops incubated in vitro with CP-96,345 showed a diminished TNFalpha release. Our results indicate that activated LPMs secrete SP during toxin A enteritis that can lead to secretion of cytokines, suggesting an autocrine/paracrine regulation of cytokine secretion by SP from LPMs during intestinal inflammation.
Castagliuolo
I
I
Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
Keates
A C
AC
Qiu
B
B
Kelly
C P
CP
Nikulasson
S
S
Leeman
S E
SE
Pothoulakis
C
C
D000818:Animals; D001427:Bacterial Toxins / Q000494:pharmacology; D001713:Biphenyl Compounds / Q000494:pharmacology; D016360:Clostridioides difficile; D004768:Enterotoxins / Q000494:pharmacology*; D005727:Ganglia, Spinal / Q000378:metabolism*; D007079:Ileitis / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000378:metabolism; D008161:Lumbosacral Region; D008262:Macrophage Activation; D008264:Macrophages / Q000378:metabolism*; D008297:Male; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D013373:Substance P / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D001427:Bacterial Toxins; D001713:Biphenyl Compounds; D004768:Enterotoxins; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; C041348:tcdA protein, Clostridium difficile; D013373:Substance P; C066892:CP 96345