GPER1-unrelated immune activity of 4HT and TAM
Macrophages express GPER1 and not ERβ (Pepe et al., 2017). We therefore evaluated the involvement of GPER1 in 4HT and TAM activity. The expression of Vegfα and other E2-target genes (i.e. IL1β and arginase 1 (Arg1), was analyzed upon treatment with increasing concentrations of GPER1 selective ligand G1, which we analyzed in parallel with 4HT, TAM and E2. While the highest G1 level provided similar effects on Vegfα expression, strong differences were detected on IL1b and Arg1, as the expression of these genes was strongly inhibited by 4HT and TAM, but significantly induced by G1 and E2 (Figure 2). Such differences were not due to ligand-induced alterations in receptor expression, as ERα and GPER1 mRNAs did not vary in response to any treatment used (Supplementary Figure 2A). Altogether, these and previous results show that high concentrations of 4HT and TAM elicit macrophage responses that are ERα and GPER1-independent and distinct from those induced by the physiological ligand, E2.