Modulation of Hepatic Cholesterol-Related Pathways by Ophiocordyceps sinensis and Coenzyme Q10 in a Sequential Gut–Liver In Vitro Model

Dysregulated hepatic cholesterol handling and oxidative stress represent key targets for nutritional interventions. This study investigated a combination of Ophiocordyceps sinensis (formerly Cordyceps sinensis) extract and coenzyme Q10 (CoQ10) using a sequential gut–liver in vitro model. Differentiated Caco-2/HT29-MTX co-cultures were used to assess intestinal transport, transepithelial electrical resistance (TEER), and junctional organisation. The resulting basolateral intestinal-conditioned medium was applied to high-glucose-stressed HepG2 cells. The combined treatment-maintained epithelial electrical integrity (TEER > 400 Ω·cm2) and tight junction protein abundance, while transiently increasing paracellular fluorescein transport (Papp) and enhancing basolateral CoQ10 recovery (+29%). In HepG2 cells, the conditioned medium reduced superoxide production (−38%) and enhanced both DiI-labelled low-density lipoprotein (DiI-LDL) uptake (+26%) and intracellular total bile acid content (+33%). These functional outcomes were accompanied by coordinated changes in protein abundance: a decrease in sterol regulatory element-binding protein 2 (SREBP-2), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), and proprotein convertase subtilisin/kexin type 9 (PCSK9) levels, alongside increased low-density lipoprotein receptor (LDLR), cytochrome P450 family 7 subfamily A member 1 (CYP7A1), and ATP-binding cassette transporter A1 (ABCA1) expression. Pharmacological inhibition with dorsomorphin suggested a partial involvement of AMP-activated protein kinase (AMPK) signalling, although this mechanistic assessment remained exploratory. Overall, these findings demonstrate the coordinated modulation of intestinal transport, functional hepatic endpoints, and cholesterol-related protein abundance.