Figure 6. Overview of prostanoid synthase expression and relative activity in different macrophage cell types after long-term TLR-4 activation.

Metabolism of AA in (A) RPM, (B) TGEM, (C) BMDM, and (D) RAW through induced COX-2 leads to a pool of PGH₂ that is metabolized by TBXS, PGIS, PGDS (H-PGDS), and induced PGES (mPGES-1). Percentages of metabolites (circles) and enzyme transcripts (squares) in each cell type are represented by area after 8 h KLA stimulation. Metabolites and expressed levels of PGES, PGDS, and TBXS are roughly proportional, although the presence of PGIS appears to selectively draw substrate away from PGES but not PGDS. Low constitutive expression level of PGIS in RPM and TGEM macrophages with disproportionately high levels of PGI₂ suggests a significantly higher synthetic rate compared with other prostanoid synthases.