Forskolin-Mediated Modulation of human T Helper Cell Differentiation Dadova P. 1,2, Mikulova A.1,2, Jarousek R. 1,2, Kubala L. 1,2,3 1 Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic 2 Institute of Biophysics of the Czech Academy of Sciences, Brno, Czech Republic 3 ICRC-CBCE, St. Anne's University Hospital, Brno, Czech Republic Forskolin (FSK) is a labdane diterpene that is suggested as a potential immunomodulator. It is well known as an activator of cAMP signalling pathway. However, specific effects of FSK-mediated cAMP elevation on T helper (Th) cell differentiation and functions are still unclear. We speculate that increased levels of cAMP in Th cells may have distinct effects on each differentiation program. Our study is therefore aimed to clarify this effect on Th1, Th2 and Th17 subpopulations. Modulation of Th cell differentiation via stimulation of cAMP signalling pathway can contribute to identification of novel therapeutic targets for the treatment of Th cell-related pathological processes. Human Th naive cells were sorted and stimulated by selected activators and cytokines to induce differentiation into Th1, Th2 and Th17 subpopulations. Subsequently, part of the samples was treated with 10 µM FSK during the differentiation process. Expression profiles of distinct subpopulations were then determined on single-cell scale, using 10X Genomics technology. Based on data analysis using Seurat tool in RStudio, differential expression between samples treated and non-treated with FSK was detected. The output of our analysis clearly shows not only the changes in expression of specific genes for distinct subpopulations and cAMP signalling-related genes, but it also suggests the possibility of Th17/Treg plasticity.