Posted by A recent review in The Journal of Steroid Biochemistry and Molecular Biology explores how 7-ketocholesterol (7KC) contributes to cellular dysfunction, and how cyclodextrins could offer a strategy for selectively removing these toxins.
Cholesterol is essential to every cell in the human body. It helps maintain cell membranes, supports hormone production, and serves as a precursor for bile acids and vitamin D. But when cholesterol undergoes oxidation, the resulting oxysterols can have very different – and potentially damaging – biological effects. One of the most abundant and biologically significant of these oxysterols is 7KC.
Why does 7KC accumulate?
7KC is primarily produced through the non-enzymatic oxidation of cholesterol at its C7 position. It only takes one oxidation event to turn essential cholesterol into harmful 7KC. Because 7KC is relatively chemically stable, it persists and accumulates in biological tissues more readily than other short-lived oxysterols. Elevated 7KC has been identified in oxidized LDL, atherosclerotic plaques, the retina, the brain, and other tissues affected by chronic oxidative stress. This stability makes 7KC a potentially useful marker of lipid oxidation, while its accumulation can actively interfere with cellular function.
A driver of cellular dysfunction
The biological effects of 7KC span several interconnected pathways. 7KC increases oxidative stress, impairs peroxisomal function, disturbs lysosomal activity, promotes endoplasmic reticulum stress, and activates inflammatory signaling pathways. These effects can reinforce one another: while oxidative stress generates more oxidized lipids, stressed mitochondria produce additional reactive oxygen species. Inflammatory signaling further disrupts tissue homeostasis, creating a self-sustaining cycle of oxidation, inflammation, and cellular injury. At sufficiently high levels, 7KC can induce a complex form of cell death involving oxidative stress, apoptosis, and disrupted autophagy sometimes described as “oxiapoptophagy.”
These mechanisms may help explain why 7KC has been associated with a wide range of conditions, including cardiovascular disease, neurodegenerative disease, age-related macular degeneration, metabolic disorders, and other diseases characterized by chronic inflammation and oxidative damage. In atherosclerosis, for example, 7KC is abundant within oxidized LDL and arterial plaque. Its accumulation can impair macrophages, promote their conversion into lipid-laden foam cells, and reduce their ability to clear cellular debris. This contributes to plaque inflammation and instability rather than simply adding to the total cholesterol burden.
Cyclodextrins to the rescue!
The review discusses several potential approaches for mediating 7KC-induced damage. These include preventing oxidation, modifying downstream signaling, enzymatically degrading 7KC, and physically removing it from cells and tissues. The last approach is especially relevant to cyclodextrin research:
Cyclodextrins are well known for their ability to encapsulate hydrophobic guest molecules within their cavities. However, conventional CDs can interact broadly with cholesterol and other lipids, creating challenges when the objective is to remove a harmful oxysterol without disrupting the cholesterol needed for normal cellular function.
The review features UDP-003, a purpose-built CD dimer developed by Cyclarity Therapeutics, as an example of a more selective strategy. UDP-003 is designed to bind and extract 7KC preferentially over cholesterol, despite their chemical similarity. Previous studies have shown that selective 7KC removal can reduce oxidative stress and lipid accumulation while restoring macrophage functions impaired by 7KC exposure.
This represents an important evolution in the therapeutic use of cyclodextrins: moving from general-purpose complexation toward molecularly engineered hosts designed for a specific pathological target.
A broader view of oxidized cholesterol
This review also highlights the need for better methods to distinguish closely related oxysterols, quantify 7KC, and determine which oxysterol forms are most active in different tissues. These efforts reflect a broader shift beyond measuring total cholesterol and toward understanding how specific oxidized forms contribute to cellular dysfunction and disease.
For the cyclodextrin community, this creates an opportunity to develop increasingly precise host–guest systems for targets that conventional drugs may struggle to address. Selective recognition and removal of pathological lipids could expand the role of cyclodextrins beyond formulation and drug delivery, positioning them as active therapeutic agents.
Reference: Dias IHK, Petler N, Harihararajah K, Kremenska Y, Anderson AM, O’Connor MS. Emerging role of 7-Ketocholesterol and hydroxylated 7-Ketocholesterol in the pathophysiology of disease. Journal of Steroid Biochemistry and Molecular Biology. 2026;260:106981. PubMed | DOI
