Figure 7.

The role of PG in SR‐A‐mediated signaling during macrophage adhesion. SR‐A‐mediated macrophage adhesion involves the activation of a Src kinase, PI3K, PLA₂, and 12/15‐LOX (Fig. 1 and refs. [16, 18]). Previous studies show that the Src kinase Lyn mediates the activation of PI3K during SR‐A‐mediated adhesion [18]. The current results (Fig. 2) indicate that PLA₂ is also activated by a Src kinase (e.g., Lyn) and that COX‐derived products (PGE₂, PGI₂, and TXA₂) are produced following the PLA₂‐dependent generation of AA (Fig. 4). PGE₂ suppresses TNF‐α and promotes IL‐10 production via binding to the EP4 receptor (Figs. 5 and 6), which elicits responses via G_s and adenylyl cyclase (AC). Although activation of the G_s‐coupled IP receptor can mediate similar effects on cytokine production (dotted lined), the amount of PGI₂ produced during SR‐A‐mediated macrophage adhesion is not sufficient to elicit these responses. TXA₂, which is also produced, has no effect on cytokine production during SR‐A‐mediated macrophage adhesion.