Do hs-CRP, Lp-PLA2, and MPO reflect different kinds of inflammatory activity?

At age 52, these biomarkers can add biological context to cardiovascular risk assessment, but they do not function as anatomical tests for coronary plaque.

Clinical and prognostic evidence

• hs-CRP is a validated marker of integrated systemic inflammation. In prospective data, hs-CRP >3 versus <1 mg/L was associated with about 60% higher incident CHD risk after Framingham-risk adjustment; one cohort reported adjusted HR 1.50 per 1-SD increase in log-hs-CRP. Persistent hs-CRP ≥2.0 mg/L is an ACC/AHA risk-enhancing factor when measured during clinical stability.
• Higher Lp-PLA2 activity is associated with coronary events (approximately 12% higher risk per SD increase), but has not significantly improved risk reclassification.
• Higher MPO is associated with angiographic coronary disease and subsequent events; in stable CAD, MPO >322 pmol/L predicted 3-year major adverse cardiovascular events after multivariable adjustment.

Mechanistic interpretation

• hs-CRP is a liver-derived acute-phase protein induced primarily by IL-6 (also IL-1β and TNF-α), so it reflects systemic signaling but not its cause or vascular location.
• Lp-PLA2 is found in plaque macrophages and necrotic cores; oxidized-phospholipid hydrolysis products can amplify endothelial and plaque inflammation.
• MPO from activated neutrophils and monocytes generates oxidants that modify LDL/HDL, impair endothelial function, and may promote plaque instability. Circulating MPO correlates with carotid plaque inflammation on FDG-PET/CT.

Practical interpretation

• Normal hs-CRP, Lp-PLA2 activity, or MPO is reassuring only in the narrow sense that marked inflammatory activity is not detected by that assay. Normal values do not exclude atherosclerosis, including stable or noncalcified plaque.
• For anatomical risk clarification, CAC >0 indicates subclinical atherosclerosis and CAC has stronger evidence than these inflammatory biomarkers for risk stratification.

Bottom line

• The claim is supported: hs-CRP primarily reflects systemic inflammation, whereas Lp-PLA2 and especially MPO relate biologically to vascular/plaque inflammation; none should be used to rule out atherosclerosis or replace established risk assessment and selectively used CAC imaging.