7-ketocholesterol as a theranostic target: Potential applications and future perspectives

7-Ketocholesterol (7KC) is mainly formed by cholesterol autoxidation and is a pro-oxidant and pro-inflammatory bioactive lipid that also induces different types of cell death, including oxiapoptophagy. It is frequently associated with major age-related diseases, such as cardiovascular diseases, age-related macular degeneration, and Alzheimer's disease. 7KC can therefore be considered a biomarker for these diseases, offering the possibility of developing theranostic strategies combining diagnosis and treatment. Currently, all the elements are in place to develop tools for the design of theranostic therapies targeting 7KC in diseased organs: antibodies, nanoparticles used as nanoplatforms, molecules that neutralize 7KC such as enzymes which degrade it, as well as natural or synthetic compounds that inhibit the cytotoxic signaling pathways associated with oxidative stress, inflammation and cell death activated by 7KC. Identifying and neutralizing 7KC biological activities using a theranostic approach could also be of interest for growing medical fields such as space medicine widely concerned by oxidative stress, aging and age-related diseases, driven by microgravity. This review supports that most of key tools are now available to develop theranostic treatments targeting 7KC in age-related pathologies, especially in cardiovascular diseases associated with atheroma, but also in age-related macular degeneration and Alzheimer's disease. Discovery of effective treatments for these diseases is a major challenge and will answer an important need for both patients and caregivers.