Genetically predicted expression of cuproptosis and copper-transport genes and coronary artery disease risk: a cis-Mendelian randomization and colocalization study
This study utilizes cis-Mendelian randomization and colocalization analyses to demonstrate that while cuproptosis and copper-transport genes are upregulated in atherosclerotic plaques, their genetically predicted baseline expression does not causally influence coronary artery disease risk, suggesting their plaque presence is a consequence rather than a driver of the disease.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of a preprint that has not been peer-reviewed. It is not medical advice. Do not make health decisions based on this content. Read full disclaimer
Heart disease remains the leading cause of death worldwide. Even with powerful medicines that lower cholesterol, many people still face a significant risk of heart attacks and strokes. This lingering danger has pushed scientists to search for new causes and new ways to treat the disease. One promising avenue of research focuses on copper, a trace mineral that our bodies need to function but which can become toxic if not carefully managed. In 2022, researchers discovered a specific way that cells die when they are overwhelmed by copper, a process they named cuproptosis. Because heart disease involves the buildup of fatty, inflamed patches in the arteries, and because these patches are full of dying cells, scientists began to wonder if this copper-driven cell death was a hidden cause of the disease. Early studies looked at tissue samples from patients with heart disease and found that genes responsible for managing copper were indeed active and changed in these damaged areas. This led to a hopeful idea: perhaps blocking these genes or fixing copper levels could stop heart disease before it starts.
However, finding a change in a gene within a sick tissue does not prove that the change caused the sickness. It is often the other way around: the disease itself changes the genes. To solve this puzzle, a team of researchers set out to test whether the natural, lifelong levels of these copper-related genes actually drive the risk of coronary artery disease. They used a method that treats human genetics like a natural experiment. Since our genes are fixed at conception and cannot be changed by the disease itself, they serve as a reliable way to see if a gene is a cause or just a symptom. The researchers focused on a specific set of genes that control how cells import, export, and process copper, including the ones involved in the newly discovered cuproptosis process. They analyzed data from nearly 182,000 people with coronary artery disease and compared them to over a million people without the disease. They also looked at gene activity in blood and artery tissues to build a complete picture.
The study began by confirming what earlier researchers had seen. When the team examined tissue samples from carotid arteries in two different groups of patients, they found that the genes managing copper were indeed behaving differently in the diseased plaques compared to healthy tissue. Specifically, the genes that bring copper into cells were turned up, while the gene that pumps copper out was turned down. This pattern was not random; it tracked perfectly with the number of immune cells, such as macrophages, that had gathered in the plaque. The more inflamed the tissue was, the more these copper genes changed. This confirmed that the copper genes are part of the disease landscape, but it did not yet prove they were the drivers.
To find out if these genes were the cause, the researchers used their genetic data to predict what would happen if a person had naturally higher or lower levels of these genes throughout their entire life. They tested eleven key genes, including those that import copper and those that trigger the cell death process. They also included a known gene, LPL, as a control to make sure their method was working correctly. As expected, the control gene showed a strong, protective effect, proving the team's approach was sound. But when they turned to the copper genes, the results were clear and consistent: none of them showed a causal link to heart disease. Even for the genes that looked most promising in the tissue samples, the genetic evidence showed no increase or decrease in heart disease risk.
The researchers found that two genes, MTF1 and DLAT, appeared to have a small effect in a preliminary check, but a deeper look revealed this was a trick of the data. These genes sit near other genetic signals that are known to affect heart disease, and the initial analysis had mistakenly blamed the copper genes for the effect of their neighbors. Once the team separated these signals, the apparent connection vanished. For the most important genes, such as those that transport copper into cells or regulate the cell death process, the study was powerful enough to rule out any meaningful effect. The data showed that having naturally higher or lower levels of these genes does not change a person's risk of developing coronary artery disease.
The study concludes that the changes in copper genes seen in heart disease tissue are likely a reaction to the disease, not the cause. The inflamed environment of a heart plaque seems to trigger these genes as a response to the presence of immune cells, rather than the genes themselves starting the trouble. This finding suggests that while copper metabolism is active in diseased arteries, trying to target these specific genes to prevent heart disease might be ineffective. The upregulation of these genes is a marker of the disease's presence, a sign of the inflammatory battle taking place within the artery wall, rather than the spark that started the fire. While this does not rule out the possibility that copper plays a role in the local death of cells within a plaque, it indicates that the genetic blueprint for these genes does not determine a person's lifelong risk of heart disease. The search for new treatments must now look elsewhere, or perhaps focus on the inflammatory processes that these genes are simply following.
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