Tacrolimus Triggers Transient Receptor Potential Vanilloid-1-Dependent Relapse of Pancreatitis-Related Pain in Mice

FK506 (tacrolimus) causes pain sensation through the activation of transient receptor potential ankyrin 1 (TRPA1) channels

FK506 (tacrolimus) is an immunosuppressant widely used as an ointment in the treatment of atopic dermatitis. However, local application of FK506 can evoke burning sensations in atopic dermatitis patients, and its mechanisms are unknown. In this study, we found that FK506 activates transient receptor potential ankyrin 1 (TRPA1) channels. In Ca2+-imaging experiments, increases in intracellular Ca2+ concentrations ([Ca2+]i) by FK506 were observed in HEK293T cells expressing hTRPA1 or hTRPM8. FK506-induced currents were observed in HEK293T cells expressing hTRPA1 or mTRPA1, but less or not at all in cells expressing hTRPV1 or hTRPM8 using a patch-clamp technique. FK506 also evoked single-channel opening of hTRPA1 in an inside-out configuration. FK506-induced [Ca2+]i increases were also observed in TRPA1-expressing mouse primary sensory neurons. Furthermore, injection of FK506 evoked licking or biting behaviors and these behaviors were almost abolished in TRPA1 knockout mice. These results indicate that FK506 might cause pain sensations through TRPA1 activation.

Effect of oral administration of β-glucans derived from Aureobasidium pullulans SM-2001 in model mice and rat with atopic dermatitis-like phenotypes

In this study, we investigated the anti-atopic dermatitis (AD) activity of β-glucans derived from Aureobasidium pullulans SM-2001 (βGdAP). βGdAP was orally administered to AD animal models such as vasodilation, allergic pruritus and contact dermatitis. Administration of βGdAP attenuated the amount of Evans blue solution on vasodilation rat. Scratching behaviors, secretion of histamine and ear thickness were significantly (p < 0.05) attenuated in the βGdAP-treated mouse groups. Interestingly, transcriptional expression of T-bet, a transcription factor for Th1 reactions, was increased, but that of GATA-3, a transcription factor for Th2 reactions, was attenuated in the βGdAP-treated groups (p < 0.05). In addition, we found that reduced transcriptional expression of forkhead box P3 and galectin-9, regulators of regulatory T cells, was recovered in the βGdAP-treated groups (p < 0.05). Taken together, these data indicate that administration of βGdAP could effectively attenuate AD-like phenotypes via regulation of Th1/Th2 transcriptional activity and Treg activation.