The Immunosuppressant Macrolide Tacrolimus Activates Cold-Sensing TRPM8 Channels

Abstract

TRPM8 is a polymodal, nonselective cation channel activated by cold temperature and cooling agents that plays a critical role in the detection of environmental cold. We found that TRPM8 is a pharmacological target of tacrolimus (FK506), a macrolide immunosuppressant with several clinical uses, including the treatment of organ rejection following transplants, treatment of atopic dermatitis, and dry eye disease. Tacrolimus is an inhibitor of the phosphatase calcineurin, an action shared with cyclosporine. Tacrolimus activates TRPM8 channels in different species, including humans, and sensitizes their response to cold temperature by inducing a leftward shift in the voltage-dependent activation curve. The effects of tacrolimus on purified TRPM8 in lipid bilayers demonstrates conclusively that it has a direct gating effect. Moreover, the lack of effect of cyclosporine rules out the canonical signaling pathway involving the phosphatase calcineurin. Menthol (TRPM8-Y745H)-and icilin (TRPM8-N799A)-insensitive mutants were also activated by tacrolimus, suggesting a different binding site. In cultured mouse DRG neurons, tacrolimus evokes an increase in intracellular calcium almost exclusively in cold-sensitive neurons, and these responses were drastically blunted in Trpm8 KO mice or after the application of TRPM8 antagonists. Cutaneous and corneal cold thermoreceptor endings are also activated by tacrolimus, and tacrolimus solutions trigger blinking and cold-evoked behaviors. Together, our results identify TRPM8 channels in sensory neurons as molecular targets of the immunosuppressant tacrolimus. The actions of tacrolimus on TRPM8 resemble those of menthol but likely involve interactions with other channel residues.

Hypothermia induces changes in the alternative splicing pattern of cold-inducible RNA-binding protein transcripts in a non-hibernator, the mouse

“…It is well known that TRP channels play roles in thermo-sensation. TRPM8 and TRPA1 channels can be activated within ranges of temperatures less than 37°C (2,3). Therefore, it was of interest to assess the involvement of these cold-sensitive channels in the shift in the splicing pattern.…”

Recent Progress in TRPM8 Modulation: An Update

“…The group of Viana recently described that the immunosuppressant Tacrolimus ( 29 , Figure 2) activates the TRPM8 channels in different species, increasing intracellular calcium through cold-sensitive neurons, a response that was significantly reduced in TRPM8 knockout (KO) mice or by application of selective antagonists [66]. Although this macrocyclic compound caused blinking and cold-evoked behaviors, its activity on menthol and icilin-insensitive mutants suggested a binding site different to that of the small-molecule natural products.…”

Pearls in Mitigating Application Pain of Topical Nonsteroidal Agents

“…Cold stimuli incite the release of the inhibitory neurotransmitter glutamate from TRPM8 channels, thus decreasing the transmission of noxious stimuli to the central nervous system [21]. Tacrolimus has recently been shown to activate TRPM8[10], which may suggest an additive effect when the overlying moisturizer is cooled before it is applied.…”

“…Aspirin directly inhibits the TRPV1 channel, which in turn decreases the release of substance P by the afferent nerve fibers. This, combined with the inhibition of prostaglandin synthesis, may explain this effect [10]. Evidence of this practice is limited, and, importantly, its use for children has not been reported; it may nonetheless be a reasonable option for certain patients.…”

“…The mechanisms by which SSAs produce pain are poorly understood. The leading theories involve the upregulation of nociceptive neuropeptides such as substance P and calcitonin gene-related peptide (CGRP) via the activation of the cation channels TRPV1 and TRPA1 on sensory neurons [8-10]. The increased neurosensory response to itch and pain stimuli in AD patients may also partially contribute to increased application site pain with SSAs [11].…”