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.