PTGS2 and obesity due to melanocortin 4 receptor deficiency: Obesity disrupts 17-HDHA and PD1 biosynthesis (122); S. aureus infection in macrophages elevates COX-2/mPGES-1 but suppresses 15-LOX-1, impairing SPM production (123); and fatty acid desaturase 1 deficiency alters hepatic PUFA metabolism, limiting SPM synthesis (124).