During resolution of acute inflammation, which lipid mediator is primarily responsible for switching macrophage phenotype from M1 (pro-inflammatory) to M2 (pro-resolving) and promoting efferocytosis of apoptotic neutrophils?

• A Lipoxin A4 ✓
• B Resolvin E1
• C Protectin D1 (neuroprotectin D1)
• D Maresin 1

Explanation

Lipoxin A4 (LXA4), derived from arachidonic acid via the 5-LOX and 15-LOX pathways, was the first identified 'stop signal' of inflammation. It acts on ALX/FPR2 receptors to inhibit neutrophil recruitment, promote macrophage efferocytosis of apoptotic neutrophils, and shift macrophages toward an M2 pro-resolving phenotype. While resolvins, protectins, and maresins (derived from EPA/DHA) also promote resolution, LXA4 is the archetypal endogenous lipid mediator of inflammation resolution and represents the conceptual 'pro-resolving' class identified first by Charles Serhan.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.