Interleukin-10 contributes to PGE2 signalling through upregulation of EP4 via SHIP1 and STAT3

Abstract

Macrophage cells form part of our first line defense against pathogens. Macrophages become activated by microbial products such as lipopolysaccharide (LPS) to produce inflammatory mediators, such as TNFα and other cytokines, which orchestrate the host defense against the pathogen. Once the pathogen has been eradicated, the activated macrophage must be appropriately deactivated or inflammatory diseases result. Interleukin-10 (IL10) is a key anti-inflammatory cytokine which deactivates the activated macrophage. The IL10 receptor (IL10R) signals through the Jak1/Tyk2 tyrosine kinases, STAT3 transcription factor and the SHIP1 inositol phosphatase. However, IL10 has also been described to induce the activation of the cyclic adenosine monophosphate (cAMP) regulated protein kinase A (PKA). We now report that IL10R signalling leads to STAT3/SHIP1 dependent expression of the EP4 receptor for prostaglandin E 2 (PGE 2). In macrophages, EP4 is a G αsprotein coupled receptor that stimulates adenylate cyclase (AC) production of cAMP, leading to downstream activation of protein kinase A (PKA) and phosphorylation of the CREB transcription factor. IL10 induction of phospho-CREB and inhibition of LPS-induced phosphorylation of p85 PI3K and p70 S6 kinase required the presence of EP4. These data suggest that IL10R activation of STAT3/SHIP1 enhances EP4 expression, and that it is EP4 which activates cAMP-dependent signalling. The coordination between IL10R and EP4 signalling also provides an explanation for why cAMP elevating agents synergize with IL10 to elicit anti-inflammatory responses.

Interleukin-10 Induces Expression of Neuroendocrine Markers and PDL1 in Prostate Cancer Cells

“…Autocrine/paracrine produced prostaglandin E2 (PGE2) binds to the prostaglandin E2 receptor 4 (EP4) and can support proliferation of PCa cells by stimulating PI3K/Akt and cAMP-dependent PKA pathways [ 42 ]. PGE2 has been reported to induce NED phenotype in PCa cells [ 43 ], and in our work with macrophages we found that IL10 induction of EP4 protein is required for IL10 action in these cells [ 44 ]. Thus, we examined whether IL10 or IL6 might upregulate EP4 expression to promote PGE2-induced NED.…”

“…We also examined whether IL10 or IL6 might upregulate the PGE2 receptor, EP4, to promote PGE2-induced NED. In our studies of IL10 action in macrophage cells, we found IL10 induction of EP4 protein expression is needed for IL10 inhibition of macrophage production of inflammatory cytokines [44]. In PCa cells, activation of EP4 by PGE2 has been reported to increase the expression of metastatic-related proteins [42].…”

Choline Glycerophospholipid-Derived Prostaglandins Attenuate TNFα Gene Expression in Macrophages via a cPLA2α/COX-1 Pathway

“…Recent evidence suggests the existence of a regulatory interplay between the production of certain cytokines or chemokines and the synthesis/action of eicosanoids or their receptors. This is exemplified by studies showing that TNFα and PGE 2 act synergistically to induce IL-8 expression [ 61 ], and that IL-10, a cytokine with proven anti-inflammatory functions, contributes to PGE 2 signaling through the upregulation of the EP4 receptor [ 62 ]. Therefore it seemed reasonable to investigate whether a connection existed in our system between early PG production and cytokine expression.…”

Interleukin-10 and Small Molecule SHIP1 Allosteric Regulators Trigger Anti-inflammatory Effects through SHIP1/STAT3 Complexes

“…This implies that a protein other than STAT3 might contribute to IL10 action. Our previous cell-culture-based studies suggested that SHIP1 participates in IL10 action ( Chan et al., 2012 ; Cheung et al., 2013 ; Samiea et al., 2020 ). We now looked in vivo at the ability of IL10 to inhibit LPS-induced inflammatory cytokine expression ( Figure 1 A) in SHIP1 +/+ and SHIP1 −/− mice and found IL10 inhibited TNFα in SHIP1 +/+ but not SHIP1 −/− mice.…”