24-hydroxycholesterol replacement rate measured in blood is a non-invasive biomarker of brain demyelination and remyelination in cuprizone-treated mice

• Published in: Experimental neurology Vol. 364; p. 114395
• Main Authors: Shankaran, Mahalakshmi, Mohammed, Hussein, Tsang, Ellen, Wong, Po-yin Anne, Protasio, Joan, Murphy, Elizabeth J., Bernard, Frederic, Chang, Rui, Dellovade, Tammy, Turner, Scott, Hellerstein, Marc K.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.06.2023
• Subjects: 24-hydroxycholesterol; Animals; Biomarker; Biomarkers - metabolism; Brain; Brain - metabolism; Cholesterol - adverse effects; Cholesterol - metabolism; Corpus Callosum - metabolism; Cuprizone; Cuprizone - toxicity; Demyelinating Diseases - chemically induced; Demyelinating Diseases - drug therapy; Demyelinating Diseases - metabolism; Disease Models, Animal; Lipids; Mice; Mice, Inbred C57BL; Myelin; Myelin Proteins - metabolism; Myelin Sheath; Oligodendroglia; Remyelination; Turnover; Brain; Biomarker; thyroid hormone; Lipids; experimental autoimmune encephalomyelitis; fractional synthesis rate; gas chromatography - mass spectrometry; Cuprizone; Turnover; corpus callosum; phosphatidyl serine; phosphatidyl choline; Remyelination; Myelin; multiple sclerosis; myelin basic protein; 24-hydroxycholeserol; mass isotopomer distribution analysis; galactocereboside; phosphatidylethanolamine; liquid chromatography - mass spectrometry; 2',3'-cyclic-nucleotide 3'-phosphodiesterase; phosphatidic acid; 24-hydroxycholesterol; phospholipid
• ISSN: 0014-4886; 1090-2430
• DOI: 10.1016/j.expneurol.2023.114395

In mice, dietary cuprizone causes brain demyelination with subsequent spontaneous remyelination upon return to normal chow. Heavy water (2H2O) labeling with mass spectrometric analysis can be used to measure brain de novo synthesis of several myelin components including cholesterol, phospholipids, galactocereboside (GalC) and myelin-associated proteins. 24-hydroxycholesterol (24-OHC), the major metabolite of brain cholesterol, is detected in blood and is believed to be specifically derived from CNS cholesterol metabolism. We assessed changes in syntheses of myelin components in brain and of blood sterols during cuprizone-induced experimental demyelination and remyelination, with and without thyroid hormone (T3) treatment. Mice were fed cuprizone for 4 weeks, then returned to control diet and treated with either placebo or T3 (0.005 mg/day). 2H2O was administered for the last 14 days of cuprizone diet, and for either 6, 12 or 19 days of treatment during recovery from cuprizone, after which blood and corpus callosum (CC) samples were collected (n = 5/time point/treatment). 2H incorporation into cholesterol and 24-OHC in blood and CC, and incorporation into phospholipid (PL)-palmitate, GalC, myelin basic protein (MBP) and 2′,3′-cyclic-nucleotide 3′-phosphodiesterase (CNPase) in CC were measured. Cuprizone significantly (p < 0.05) decreased syntheses of cholesterol, 24-OHC, GalC, MBP, CNPase and PL-palmitate in the CC and these effects were all reversed during recovery. T3 treatment significantly (p < 0.05) increased syntheses of cholesterol, 24-OHC and palmitate compared to placebo. 24-OHC and cholesterol turnover rates in brain and blood were nearly identical and 24-OHC rates in blood paralleled rates in CC, indicating that blood 24-OHC derives primarily from the brain and reflects oligodendrocyte function. In summary, changes in synthesis of several lipid and protein components in brain during cuprizone-induced demyelination and remyelination are measurable through stable isotope labeling. Blood 24-OHC turnover rates closely reflect flux rates of brain cholesterol in response to cuprizone and T3, which alter oligodendrocyte function. Labeling of blood 24-OHC has potential as a non-invasive marker of brain de novo cholesterol synthesis and breakdown rates in demyelinating conditions. •Deuterated water labeling measures synthesis of brain myelin lipids and proteins.•Myelin lipid and protein synthesis are altered by cuprizone and during recovery.•Brain and blood 24-OHC turnover reflects changes in brain cholesterol turnover.•Thyroid hormone increases myelin lipid synthesis during recovery from cuprizone.