Castagliuolo I, Keates A C, Qiu B, Kelly C P, Nikulasson S, Leeman S E, Pothoulakis C
Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
Proc Natl Acad Sci U S A. 1997 Apr 29;94(9):4788-93. doi: 10.1073/pnas.94.9.4788.
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.
我们之前报道过，用P物质（SP）拮抗剂CP-96,345预处理大鼠可抑制艰难梭菌毒素A注入回肠肠袢后引起的肠毒性反应，这表明SP参与了肠道对该毒素的反应。我们现在报道，将毒素A注入大鼠回肠后，在毒素A给药30 - 60分钟后，腰段背根神经节（DRG）和黏膜刮片中的SP含量迅速增加。毒素A介导的液体分泌、甘露醇通透性和回肠组织学损伤仅在2小时后显著增加。通过逆转录聚合酶链反应检测发现，毒素A还会使腰段DRG和回肠黏膜中SP mRNA的丰度增加。与从注射缓冲液的肠袢中分离的固有层巨噬细胞（LPMs）相比，从注射毒素A的肠袢中获得的LPMs释放更多的肿瘤坏死因子α（TNFα）和SP（P < 0.01）。用SP拮抗剂CP-96,345预处理大鼠可抑制毒素A介导的TNFα从分离的LPMs中释放，而SP拮抗剂的无活性对映体（CP-96,344）则没有作用。从注射毒素A的回肠肠袢中获得的LPMs在体外与SP（10^(-8)至10^(-9) M）一起孵育时，TNFα分泌增强，而从注射缓冲液的肠袢中分离的LPMs对SP无反应。此外，从注射毒素A的回肠肠袢中获得的LPMs在体外与CP-96,345一起孵育时，TNFα释放减少。我们的结果表明，在毒素A性肠炎期间，活化的LPMs分泌的SP可导致细胞因子的分泌，这表明在肠道炎症期间，LPMs分泌的SP对细胞因子分泌具有自分泌/旁分泌调节作用。
