Plasma Levels of Receptor Interacting Protein Kinase-3 Correlate with Coronary Artery Disease

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Plasma Levels of Receptor Interacting Protein Kinase-3 Correlate with Coronary Artery Disease

Coronary artery disease (CAD)—the leading cause of death globally—often relies on invasive tests like coronary angiography to diagnose subtypes (stable angina, unstable angina, heart attack) and assess severity. But a 2019 study from Peking Union Medical College Hospital suggests a simpler, blood-based biomarker could help: receptor interacting protein kinase-3 (RIP3), a key regulator of necroptosis—a type of programmed cell death that drives inflammation and artery-clogging plaque buildup.

What Is RIP3, and Why Does It Matter for CAD?

RIP3 is a protein essential for necroptosis, a process linked to diseases like atherosclerosis (the hardening of arteries). Unlike apoptosis (clean cell death), necroptosis bursts cells open, releasing inflammatory molecules that worsen plaque growth. Previous research in mice showed that losing RIP3 reduced advanced atherosclerotic lesions, while human studies found active RIP3 in vulnerable plaques—those likely to rupture and cause heart attacks.

But most studies looked at serum RIP3 (from clotted blood), which is less stable than plasma (from unclotted blood). The Peking Union team set out to test if plasma RIP3 could be a more reliable marker for CAD.

The Study: Plasma RIP3 vs. CAD

The researchers enrolled 484 people: 166 controls (no CAD history) and 318 CAD patients split into three groups:

  • Stable coronary artery disease (SCAD): Angina that doesn’t worsen.
  • Unstable angina (UA): Chest pain at rest or getting worse.
  • Myocardial infarction (MI): Heart attack (damage from blocked blood flow).

They measured plasma RIP3 using an enzyme-linked immunosorbent assay (ELISA) and assessed plaque severity with the Gensini score—a standard tool for grading coronary artery narrowing.

Key Findings

  1. Plasma RIP3 is far higher than serum RIP3: In a subset of participants, plasma RIP3 levels were 10x higher than serum (434 pg/mL vs. 39 pg/mL on average). This matters because plasma is easier to collect and more consistent.

  2. CAD patients have much higher plasma RIP3: The median plasma RIP3 level in CAD patients was 407 pg/mL—nearly double the control group’s 242 pg/mL. Even after adjusting for age, diabetes, hypertension, and cholesterol, people with plasma RIP3 above 324 pg/mL (the “cutoff” for CAD) were 6 times more likely to have CAD (odds ratio: 6.00, 95% confidence interval: 3.04–11.81).

  3. RIP3 rises with CAD severity: Plasma RIP3 levels climbed steadily from controls to SCAD (388 pg/mL), UA (387 pg/mL), and MI (455 pg/mL). The highest levels were in people who’d had a heart attack—likely because ruptured plaques release RIP3 into the blood.

  4. RIP3 predicts plaque severity and ACS risk: Higher plasma RIP3 correlated with a higher Gensini score (a measure of plaque buildup). It also tracked with acute coronary syndrome (ACS)—the life-threatening form of CAD including UA and MI. People in the top 25% of RIP3 levels were far more likely to have ACS than those in the bottom 25%.

What Does This Mean for Patients?

The study adds strong evidence that plasma RIP3 is an independent risk factor for CAD. It could:

  • Screen for CAD: A simple blood test might help identify people at risk without invasive angiography.
  • Classify subtypes: Higher RIP3 could signal ACS, helping doctors prioritize treatment for patients at risk of heart attacks.
  • Assess severity: Tracking RIP3 levels might show if plaque is worsening over time.

The link to RIP3 also supports the role of necroptosis in CAD. For example, RIP3 promotes platelet activation and blood clots—key steps in heart attacks (per a 2017 PNAS study). Blocking RIP3 could even become a new treatment target for reducing plaque inflammation.

Limitations and Future Research

The study has caveats:

  • It’s cross-sectional, so it can’t prove RIP3 causes CAD—only that they’re linked. A long-term (prospective) study is needed to confirm if high RIP3 predicts future CAD.
  • Participants were all Chinese, so results may not apply to other ethnic groups.
  • The source of plasma RIP3 (e.g., from plaques, platelets, or other cells) is still unclear.

Conclusion

Plasma RIP3 offers a promising, non-invasive way to screen for CAD, classify its severity, and identify people at risk of ACS. While more research is needed, the findings suggest RIP3 could one day join cholesterol and blood pressure as a standard tool for managing heart disease.

This study was published in the Chinese Medical Journal in 2019 by Xiao-Min Hu, Xi Chen, and colleagues from Peking Union Medical College Hospital. The full paper is available at doi.org/10.1097/CM9.0000000000000225.

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