The adenylyl cyclase (AC) signaling pathway is suggested to be a key regulator of immune system functions. However, specific effects of cyclic adenosine monophosphate (cAMP) on T helper (Th) cell differentiation and functions are unclear. The involvement of cAMP in the Th cell differentiation program, in particular the development of Th1, Th2, and Th17 subsets, was evaluated employing forskolin (FSK), a labdane diterpene well known as an AC activator. FSK mediated an elevation in Th1-specific markers reinforcing the Th1 cell phenotype. The Th2 differentiation was supported by FSK, though cell metabolism was negatively affected. In contrast, the Th17 immunophenotype was severely suppressed leading to the highly specific upregulation of CXCL13. The causality between FSK-elicited cAMP production and the observed reinforcement of Th2 differentiation was established by using AC inhibitor 2',5'-dideoxyadenosine, which reverted the FSK effects. Overall, an FSK-mediated cAMP increase affects Th1, Th2 and Th17 differentiation and can contribute to the identification of novel therapeutic targets for the treatment of Th cell-related pathological processes.

Faculty of Medicine Department of Biology Masaryk University Kamenice 5 625 00 Brno Czech Republic; International Clinical Research Center St Anne's University Hospital 656 91 Brno Czech Republic

Institute of Biophysics of the Czech Academy of Sciences 612 65 Brno Czech Republic; Department of Experimental Biology Faculty of Science Masaryk University Brno 625 00 Czech Republic

Institute of Biophysics of the Czech Academy of Sciences 612 65 Brno Czech Republic; International Clinical Research Center St Anne's University Hospital 656 91 Brno Czech Republic

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