Fig 1: PGI2-R mediates Th1 cell contraction through PKA activity(A) Top increased (orange) and reduced (blue) biological pathways based on differentially expressed genes (DEGs) derived from in vitro CD3 + CD28 stimulated CD4+ T cells isolated from wild-type (WT) or Ptgir−/− (KO) mice (n = 4, one experiment).(B) Quantification of activated PKA (phosphorylated [pPKA], normalized to total PKA [tPKA]) in IFN-γ+IL-10−, IFN-γ+IL-10+, and IFN-γ−IL-10+ CD4+ T cells generated by CD3 + CD46 activation (36 h) (n = 3, three independent experiments).(C) Amounts of pPKA in CD3 + CD46-activated T cells (18 h) (left) with or without addition of either PGE2 or PGI2 (right) (n = 5, three independent experiments).(D) Impact of PGE2 vs. PGI2 provision in the presence or absence of a PKA inhibitor (inh.) on IFN-γ and IL-10 production in CD3 + CD46-activated T cells (36 h). Representative FACS plots from one of three donors (left) with statistical analysis of cumulative data (right, n = 3, three independent experiments).(E) Effect of PKA inhibition on IL-1R2 expression by CD3 + CD46-activated T cells (36 h). Representative FACS plots from one of three donors (left) and statistical analysis of cumulative data (right, n = 3, two independent experiments).(F) Amounts of mRNAs encoding PTGES2, IL1R2, or IL10 in CD3 + CD46-activated T cells (8 h) with or without PGI2 addition to media assessed by quantitative PCR (n = 3, one experiment).(G) Effect of PGI2-R expression reduction by PTGIR siRNA treatment in CD3 + CD46-activated T cells (see also Figure S4E) on IL-10 expression and PKA and CREB activation (n = 3, three independent experiments).(H) Effect of PGI2-R expression reduction by PTGIR siRNA treatment in CD3 + CD46-activated T cells (48 h) on PTGES2, IL1R2, or IL10 transcription (n = 4–5, four independent experiments).(I) Schematic of the effects of PGE2-EP4 vs. PGI2-PGI2-R activity on CD4+ T cell PKA activation and transcription of indicated genes. The effect of PGI2-R engagement on IL10 transcription vs. translation is not clear (denoted by “?”).Groups were compared using one-way ANOVA or the Student’s t test. *p < 0.05, **p < 0.01, ***p < 0.005, ****p < 0.001. See also Figure S4.