S100A9
S100A9proteinS100A9 (calprotectin) is a key alarmin amplifying vascular inflammation and thromboinflammation through monocyte recruitment and neutrophil-platelet interactions.
Pathway placement
Cascade stepPlaque inflammation
Confidencehigh
RationaleCalprotectin subunit; DAMP and alarmin driving plaque inflammation and neutrophil-platelet cross-talk.
Also acts inPlatelet activation
Druggability
DruggableYes
Known drugs / candidates0
Small-molecule tractableYes
Antibody tractableYes
EnsemblENSG00000163220
Type I vs Type II discrimination
ScoresLow-confidence (proxy)
R — rupture / Type-I52
C — confounder / Type-II78
A — assay feasibility68
E — evidence strength29
T1DI (composite)7
Specificity differential (R−C)-25.9
Confounder panel (Type-II drivers)
No confounder evidence retrieved.
Tier: light (literature co-occurrence proxy — lower confidence). See the discrimination table for all markers.
Assay & specimen
Class-level default (no specific cleared assay)— generic method inferred from analyte class; confirm against a specific product insert before use.
Specimen
Serum or plasma
Collection tube
Serum separator (gold/red-top, SST) · K2/K3-EDTA (lavender-top)
Method / principle
Sandwich immunoassay (ELISA) — research-grade unless a cleared assay exists
Reagent / substrate
Matched anti-target antibody pair (capture + labeled detection)
Platform
ELISA microplate or multiplex (Luminex/MSD)
Turnaround · availability
Send-out / research · Research-grade (no universal clinical assay)
Literature evidence(10)
- Proteogenomic Analysis of Coronary Artery Calcification in Human Populations.Arteriosclerosis, thrombosis, and vascular biology · 2026 · PMID 41924874 · doi
- S100a9 lactylation triggers neutrophil trafficking and cardiac inflammation in myocardial ischemia/reperfusion injury.The Journal of clinical investigation · 2025 · PMID 41066195 · doi
- Novel Long Noncoding RNAAffects Monocyte Subtypes, Reducing Inflammation and Promoting Vascular Healing.Circulation · 2024 · PMID 39005211 · doi
- Neutrophil-Derived Protein S100A8/A9 Alters the Platelet Proteome in Acute Myocardial Infarction and Is Associated With Changes in Platelet Reactivity.Arteriosclerosis, thrombosis, and vascular biology · 2021 · PMID 34809447 · doi
- S100A9 is a functional effector of infarct wall thinning after myocardial infarction.American journal of physiology. Heart and circulatory physiology · 2021 · PMID 34890276 · doi
- S100A8/A9 in Myocardial Infarction.Methods in molecular biology (Clifton, N.J.) · 2019 · PMID 30710308 · doi
- Extracellular matrix proteomics identifies molecular signature of symptomatic carotid plaques.The Journal of clinical investigation · 2017 · PMID 28319050 · doi
- Myeloid-related protein-8/14 in acute coronary syndrome.International journal of cardiology · 2017 · PMID 28986057 · doi
- Beyond Cholesterol - New Cardiovascular Biomarkers.Nestle Nutrition Institute workshop series · 2016 · PMID 26764476 · doi
- Markers of plaque instability in the early diagnosis and risk stratification of acute myocardial infarction.Clinical chemistry · 2011 · PMID 22057876 · doi