Effects of Sensory Denervation by Neonatal Capsaicin Treatment on Cytokine Production and Various Immune Responses

Ha, Tai You; Lee, Jeong Ho; Park, Jae Seung; Ha, Hyun Ju; Kim, Young Hyun

Abstract

Capsaicin, the pungent principle of hot peppers, is a neurotoxin that depletes unmyelinated primary sensory neurons (polymodal nociceptors) of neuropeptides like tachykinins. However, the role of capsaicin-sensitive sensory nerve in the production of cytokines, penicillin V (PEV)-induced active fatal anaphylaxis and other immune responses is not yet fully established. Neonatal mice were pretreated s.c. with a single injection of 10 ug of capsaicin per mouse in volume of 20 ul within 5 days of age. Using 5-8 week old mice pretreated as neonates with capsaicin, the capsaicin- pretreated and vehicle-treated control mice were examined for various parameters of immune responses described above. For the induction of active fatal anaphylaxis with PEV, 8 week old mice pretreated as neonates and age-matched capsaicin- untreated control mice were sensitized i.p. with 500 ug of PEV-ovalbumin conjugate plus 2*10(9) B. pertussis and 1.0 mg alum and challenged i.v. with PEV-bovine serum albumin conjugate 14 days later. It was found that neonatal capsaicin-pretreatment significantly enhanced contact hypersensitivity to TNCB and hemagglutination response to SRBC, but significantly inhibited the proliferation response of rnurine splenocyte to Con A and LPS. Interestingly, neonatal capsaicin pretreatment significantly inhibited the intensity of PEV-induced active fatal anaphylaxis and decreased the mortality due to anaphylactic shock. It also significantly inhibited LPS- induced production of cytokines such as TNF-a, IL-1B, IL-6, IL-10, and IL-12. The capsaicin-pretreatment also resulted in an inhibition of the activation of NF-kB. Taken together, these data showed for the first time that neonatal capsaicin-pretreatment significantly inhibited an antibiotic (PEV)-induced anaphylaxis and production of various cytokines, and suggest that capsaicin-sensitive primary sensory nerve may play an important regulatory role in active fatal anaphylaxis and cytokine production, thus potentially presenting tools for immune intervention. In particular, the data presented also indicated the possibility to selectively down-modulate cytokine production and NF-kB activation may offer a broad application for therapeutic intervention in neuroimmunological diseases and other pathological situations.