Circulating nucleosome

Circulating nucleosomes refer to nucleosomes that are present in the bloodstream, released from cells undergoing stress, apoptosis, necrosis, or active secretion[3][6]. A nucleosome is the fundamental unit of chromatin, composed of ~146 base pairs of DNA wrapped around a histone octamer[1][2][4][5]. In healthy conditions, nucleosomes are packed within the nucleus to organize DNA. Cellular damage, inflammation, or cell death causes nucleosomes to be released into the circulation, where they can serve as biomarkers for a range of diseases including cancer, sepsis, and severe infections like COVID-19[3][5][6]. They play central roles in chromatin structure, gene regulation, and epigenetic signaling but are not themselves a direct therapeutic target such as an enzyme, receptor, or transporter[3][5][6]. Elevated levels of circulating nucleosomes indicate ongoing cell turnover or tissue damage and are under investigation as both prognostic and diagnostic markers, particularly in oncology and critical care[5][6]. In circulation, these nucleosomal fragments may contribute to pathophysiology, including inflammation and immune activation, and may induce organ damage if excessively present[3][6]. ## Important caveats - "Circulating nucleosomes" is **not a molecular target** in the traditional sense (e.g., not a protein, enzyme, receptor, or gene that can be inhibited or activated therapeutically). Instead, it is a disease biomarker and a product of cellular events. - There may be confusion as the term describes a state or context (circulation in blood) rather than a distinct molecular entity or drug target. - No drugs are known to directly target circulating nucleosomes for therapeutic effect; they are primarily measured as markers of disease activity or tissue injury, not as targets for intervention[5][6].

Other names

Cell-free nucleosomecf-nucleosomeblood nucleosome