Cyclooxygenase-2 (COX-2) is involved in different liver diseases, but little is known about the significance of COX-2 or its metabolites in cholestatic injury. This study was designed to elucidate the role of COX-2 expression during the pathogenesis of cholestasis. Thus, we investigated the mechanisms underlying the role of COX-2 and its derived prostaglandins in modulating cell survival, inflammation, oxidative stress status and the synthesis and excretion of bile acids (BA) in response to cholestatic liver injury. We used genetically modified mice constitutively expressing human COX-2 (hCOX-2-Tg) specifically in hepatocytes. Transgenic mice (hCOX-2-Tg) and their wild-type (Wt) littermates were either subjected to a common bile duct ligation (BDL) to establish an experimental model of obstructive cholestasis. We performed an exhaustive analysis of the different types of bile acids (total, primary, secondary, conjugated, non-conjugated and hydrophilic, α-, β- and ω-muricholic acid) in plasma and in liver tissue from Wt and h-COX-2 Tg mice. Samples were analyzed at Instituto de Investigación Sanitaria La Fe (Valencia, Spain) detecting a total of 31 analytes.

Methods 20 μL of plasma samples were spiked with deuterated internal standards stock solution. Then proteins were precipitated and supernatants were dried and reconstituted in methanol:water (50:50, V/V). Besides, approximately 50 mg of each tissue were placed in 2 ml tubes containing CK14 ceramic beads (Precellys). For each 50 mg of tissue, 300 μl of methanol and the deuterated internal standards were added and tissues were homogenized in a Precellys 24 Dual system equipped with a Criolys cooler (Precellys). Samples were analyzed using an Acquity UPLC system (Waters, UK) equipped with an Acquity UPLC BEH C18 column (1.7μm, 2.1 x 100 mm; Waters). The MS analysis was performed using a Waters Xevo TQ-XS mass spectrometer (Waters) with an ESI source working in the negative-ion mode.

Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación 10.13039/501100011033 (PID2019-108977RB-I00)

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