Expression of circadian regulatory genes is dysregulated by increased cytokine production in mice subjected to concomitant intestinal injury and parenteral nutrition

We have developed a mouse model of Parenteral Nutrition Associated Cholestasis (PNAC) in which combining intestinal inflammation and PN infusion

Altered expression of CR-dependent regulatory genes during PNAC accompanies cholestasis and is, in part, due to increased cytokine (IL-1β and TNFα) production. Evaluation of the effects of modulating CR in PNAC thus deserves further investigation.

WT, IL1KO or TNFRKO mice were exposed to dextran sulfate sodium (DSS) for 4 days followed by soy-oil lipid emulsion-based PN infusion through a central venous catheter for 14 days (DSS-PN) and the expression of key CR regulatory transcription factors evaluated. Animals were NPO on a 14 hr light-dark cycle and were administered PN continuously over 24 hrs. Mice were sacrificed, and hepatic tissue obtained at 9-10AM (Zeitgeber Z+3/Z+4 hrs). PNAC was defined by increased serum aspartate aminotransferase, alanine aminotransferase, total bile acids, and total bilirubin and the effect of i.p. injection of recombinant IL-1β (200ng/mouse) or TNFα (200ng/mouse) on CR expression was examined after 4 hrs.

In the PNAC model, DSS-PN increased serum biomarkers of hepatic injury (ALT, AST, serum bile acids) which was suppressed in both DSS-PN IL1KO and DSS-PN TNFRKO mice. In WT DSS-PN, mRNA expression of Arntl and Dec1 was suppressed corresponding to increased Nr1d1, Per2, Dbp and Dec2. These effects were ameliorated in both DSS-PN IL1KO and DSS-PN TNFRKO groups. Western analysis of the circadian transcription factor network revealed in WT mice DSS-PN significantly suppressed Reverbα, Bmal, Dbp, Per2 and Mtnr1b. With the exception of Dbp, DSS-PN mediated suppression was ameliorated by both IL1KO and TNFRKO. Intraperitoneal injection of IL-1β or TNFα into WT mice increased serum AST and ALT and suppressed mRNA expression of Nr1d1, Arntl and Clock and increased Dbp and Per2. Conclusions: Altered expression of CR-dependent regulatory genes during PNAC accompanies cholestasis and is, in part, due to increased cytokine (IL-1β and TNFα) production. Evaluation of the effects of modulating CR in PNAC thus deserves further investigation.