In fact we detected virtually no IL-17A+ cells within the Foxp3+ population. While not completely unexpected, because Foxp3 can inhibit some of the transcriptional activity of RORγt,57 Foxp3+ IL-17A+ cells have been previously reported.58 Our observation that G-1 induces
IL-10 expression in Foxp3+ RORγt+ hybrid T cells suggests that, in addition to generating IL-10 production in populations already localized at the site of inflammation, G-1 may also enhance the suppressive YAP-TEAD Inhibitor 1 function of Treg populations drawn in from the circulation. Such a response would not be unprecedented as T-bet-induced CXCR3 expression in Foxp3+ cells has been shown to play a role in targeting Treg cells to sites of Th1-type inflammation.59 If IL-10 can be stably induced in hybrid T-cell populations following in vivo G-1 treatment, their suppressive activity may be enhanced as they are
recruited to sites of ongoing inflammation. Numerous attempts have been made to harness the immunosuppressive properties of IL-10 for therapeutic benefit, many of which have been based on the use of biologics.25 To our knowledge, this is the first evidence that a synthetic small molecule can shift the balance along the Treg–Th17 axis in favour of IL-10 production, in PD-0332991 manufacturer this case by acting directly on T-cell populations. These data build on previous results demonstrating that dexamethasone and retinoic acid can elicit IL-10 from polyclonally stimulated naive T cells when IL-4, IL-12 and IFN are neutralized.60 Also worth noting is the fact that it is becoming increasingly clear that GPER probably plays a smaller role in the majority of classical estrogen responses, such as
uterine imbibition, as compared with its better known counterpart ERα.40 Hence G-1 may be associated with a more tolerable adverse effect profile. Our findings suggest that the membrane-permeable small molecule G-1 may serve as a novel T-cell-targeted immunosuppressive agent in settings where large populations of Th17 cells exist, for example in rheumatoid arthritis, inflammatory bowel disease, or psoriasis. G-1 may also prove useful for in vitro generation of IL-10-producing cells for adoptive immunotherapy. Future studies delineating the specific Mirabegron signalling mechanisms and targets of G-1 and other related compounds will be seminal to the continued development of this new class of immunoregulatory estrogenic small molecules. The selectivity of G-139,53 and its attractive pharmacological properties38 make this compound a strong candidate for pharmaceutical development, paving the way for the development of novel T-cell targeted immunotherapeutics. This work was supported by National Institutes of Health grants R01 CA116662, CA118743 and CA127731 (E.R.P.). Data were generated in the Flow Cytometry Shared Resource Center supported by the University of New Mexico Health Sciences Center and the University of New Mexico Cancer Center.