Cyclooxygenase activity assay
The effect of treatment with participant plasma and individual metabolites on the total cellular cyclooxygenase (COX) activity of primary macrophage was measured using a commercially available kit (Cayman Chemical, 760151). To induce COX-2 expression, primary macrophages were incubated with 10 ng/mL of lipopolysaccharide (LPS) (Sigma, LPS25) in RPMI and 1xPSG along with 20% participant plasma or in RPMI, 20% FBS, and 1xPSG either alone as a positive control or with isolated metabolites overnight (∼18 h) before measuring total COX activity from cell lysates. A negative control of macrophage in RPMI, 20% FBS, and 1xPSG without LPS was also performed.