Cholesterol Pathway Enzyme Targeted to Lower LDL
Researchers identified a liver enzyme that may explain how dietary cholesterol weakens the body's ability to clear LDL, with mouse studies showing improved clearance.
Updated on Nov. 2, 2026 in Nutrition
Researchers at the University of California San Diego School of Medicine reported in Nature that prolonged dietary cholesterol exposure can impair LDL clearance in the liver. A small-molecule inhibitor of the enzyme cathepsin A (CTSA) stabilized LDL receptors in lab studies and reduced circulating LDL in mice.
Why it matters
Elevated cholesterol is a major risk factor for cardiovascular disease, which the WHO linked to 19.8 million deaths worldwide in 2022. Identifying a specific pathway that links diet to LDL clearance could point toward new treatment approaches beyond current options.
The findings rest on mouse experiments, human liver cell studies, and human genetic analysis, with mice given the inhibitor for four weeks after eight weeks on a high-cholesterol diet. Mouse results do not establish human benefit, and the drug's effect on people has not yet been tested beyond an earlier Phase 1 safety trial for heart failure.
The players
University of California San Diego School of Medicine
A leading academic medical school that led the research and whose scientists identified the cholesterol-clearance pathway.
Nature
A prominent peer-reviewed scientific journal in which the study was published.
The details
Prolonged dietary cholesterol activates Ral GTPases, which send LDL receptors into liver cells to be broken down, weakening clearance of LDL from the blood. The enzyme cathepsin A helps degrade these receptors, and a small-molecule CTSA inhibitor stabilized them in laboratory studies. Human genetic analysis also linked variation in pathway-related genes to differences in blood cholesterol levels.
Timeline
August 2021 to August 2023: CDC data period showing high total cholesterol in 11.3% of US adults.
2022: WHO recorded 19.8 million cardiovascular disease deaths worldwide.
Big Picture
Statins work largely by increasing liver LDL receptor activity, so the newly identified CTSA pathway that degrades those receptors offers a distinct target for lowering LDL. Its value depends on whether blocking it proves safe and effective in human trials.
Current findings are limited to mice and lab work, so no change to cholesterol treatment is available yet. The pathway is a research target, and any future therapy would require human trials before reaching patients.
The takeaway
Dietary cholesterol can impair the liver's ability to clear LDL, and this pathway may eventually inform new therapies. Readers should treat these findings as early-stage research rather than actionable treatment advice.
What happens next
A Phase 2 trial must assess the drug's effectiveness and risks, but no dates for that trial were provided.
Further reading
For more on how diet shapes blood lipids, explore our Nutrition coverage.
Source note: This article includes information reported by Medindia.
