THE ARISING · Longevity & Healthspan
Triglyceride-Rich Particles and Lp(a) Share Blood Protein Signals of Artery Inflammation
LDL cholesterol is the number most people hear about at a heart check. A large study in the European Heart Journal suggests it may not tell the whole story: two other kinds of fat-carrying particles carry blood protein signals of inflammation that LDL does not.
The work is an observational study in people. Researchers led by Jakub Morze and Clemens Wittenbecher at Chalmers University of Technology in Sweden analysed 35,269 UK Biobank participants who had no known heart disease, stroke or peripheral artery disease at the start. They checked their findings in a second group, the Multi-Ethnic Study of Atherosclerosis, with 5,915 participants.
Three kinds of particle carry fats through the blood and all share a surface protein called apolipoprotein B: LDL, triglyceride-rich lipoproteins (TRL) and lipoprotein(a), or Lp(a). All three can lodge in artery walls. The authors note that, per particle, TRL are three to four times and Lp(a) four to five times more strongly associated with coronary artery disease than LDL, according to earlier research.
To look for reasons, the team measured 2,918 blood proteins. They linked proteins to each particle type using two approaches: standard regression and Mendelian randomization, a genetic method. Only proteins found by both were kept. That left 30 proteins tied to LDL, 471 to TRL and 53 to Lp(a).
The TRL and Lp(a) protein patterns were distinct from the LDL pattern but overlapped with each other. They shared 36 proteins, and these were enriched in inflammatory pathways.
The patterns also tracked with later disease. Over follow-up in UK Biobank, 1,599 people had a coronary event. The authors combined the proteins into a score for each particle type and adjusted for other risk factors and for measured lipoprotein levels. Each one-standard-deviation rise in the TRL score was associated with a hazard ratio of 1.16 for coronary artery disease. For Lp(a) it was 1.09 (95% confidence interval 1.03 to 1.15). For LDL it was 0.95, with a confidence interval of 0.89 to 1.02, which shows no clear link.
The authors also estimated how much of each particle's risk ran through these protein changes. Markers of immune activation and vascular remodelling, meaning changes in the structure of blood vessel walls, were consistent with explaining 62% of the TRL-associated risk and 14% of the Lp(a)-associated risk. The authors conclude that, beyond depositing fat in arteries, TRL and Lp(a) converge on inflammatory and vascular remodelling pathways that may explain their greater per-particle harm compared with LDL. That mediation estimate rests on observational assumptions.
The study did not test a treatment strategy for patients with low LDL. Its findings concern protein signatures and later coronary risk, not a demonstrated improvement in clinical care.
The finding concerns protein scores after adjustment, not evidence that LDL itself is harmless or that lowering LDL is unimportant.
For readers, the practical point is about what a standard LDL result captures. LDL-related proteins in this study mostly were not tied to later coronary disease once other measures were accounted for. Triglyceride-rich particles and Lp(a) were. Those are the measures that sit alongside LDL in the paper's account of artery risk.
Next to watch is whether trials targeting TRL or Lp(a) show that lowering them also changes these inflammatory protein signals and reduces heart events.