CEACAM1 Splice Isoforms Are Regulated by Hypoxia Inducible Factors 1 alpha (HIF-1a) to Protect Against Ischemic Injury in Mouse and Human Liver Transplantation

K. J. Dery¹, H. Kojima¹, K. Kadono², H. Hirao¹, J. Kupiec-Weglinski³

¹UCLA, Los Angeles, CA, ²Liver Transplant Surgery, UCLA, Los Angeles, CA, ³UCLA Medical Center, Los Angeles, CA

Meeting: 2022 American Transplant Congress

Abstract number: 272

Keywords: Adenoviruses, Hepatocytes, Ischemia, Warm ischemia

Topic: Basic Science » Basic Science » 14 - Ischemia Reperfusion

Session Information

Session Name: Ischemia Reperfusion

Session Type: Rapid Fire Oral Abstract

Date: Monday, June 6, 2022

Session Time: 3:30pm-5:00pm

Presentation Time: 3:50pm-4:00pm

Location: Hynes Room 302

*Purpose: CEACAM1 (CC1) is a transmembrane glycoprotein that undergoes extensive alternative splicing (AS) to generate CC1-S and CC1-L. It is currently unclear which of these two cytoplasmic isoforms is involved at the interface of immune liver injury and metabolic homeostasis.

*Methods: Murine studies used warm liver IRI (wIRI) for 6 h or 7 days to assess RNA splicing in CC1. Primary hepatocytes were cultured under hypoxia-reoxygenation (H/R) stress conditions to mimic liver wIRI. Human liver transplant biopsies were obtained 2 h after reperfusion and analyzed by qRT-PCR-assisted detection of CC1-S, HIF-1α and HIF-2α.

*Results: Longitudinal CC1 AS mRNA profiles were analyzed in a wIRI model. The peak of CC1-S occurred at 6 h (P<0.0009) and 7d (P<0.0007), reflecting combinatorial interactions at the CC1 variable exon 7. We then investigated the role of HIF-1α, as a regulator of oxidative stress. Using CoCl2, a stabilizer of HIF-1α, CC1-S protein expression increased under warm storage stress in vitro, in response to hepatocyte damage (P<0.001). Wild-type mice were treated with the in vivo HIF-1α stabilizer, dimethyloxalylglycine (DMOG), to observe whether protection against wIRI, as assessed by TUNEL-positive necrotic/apoptotic cells, sALT levels and mRNAs coding for MCP1 and CXCL10 (P=0.0056), conferred protection by inducing AS mechanisms. DMOG-treatment led to inhibition of PHD1, upregulation of RNA splicing protein hnRNP A1, and promoted CC1-AS. Gene silencing of HIF-2α during ischemic stress also led to CC1-AS. To clinically validate the murine findings, we retrospectively analyzed hepatic biopsies from fifty-five human OLT patients. We found a positive correlation between CC1 and HIF-1α levels in pre-transplant donor liver biopsies (P<0.0128). Human OLT biopsies divided into “low” (n=27) vs. “high” (n=28) CC1-S expression groups as a function of HIF-1α negatively correlated with mRNA coding for CC chemokine MCP1 (p=0.0085), and T-cell markers CD4 (p=0.0003, CD28 (p=0.0359) and TIMP1 (p=0.0404) indicating better outcomes.

*Conclusions: This novel translational study identifies oxidative stress and hepatic tissue injury as catalytic drivers of CC1-AS. The uncovered HIF-1α – CC1-S axis points towards a cytoprotective and homeostatic function in alleviating hepatic IRI and improving OLT outcomes.

To cite this abstract in AMA style:

Dery KJ, Kojima H, Kadono K, Hirao H, Kupiec-Weglinski J. CEACAM1 Splice Isoforms Are Regulated by Hypoxia Inducible Factors 1 alpha (HIF-1a) to Protect Against Ischemic Injury in Mouse and Human Liver Transplantation [abstract]. Am J Transplant. 2022; 22 (suppl 3). https://atcmeetingabstracts.com/abstract/ceacam1-splice-isoforms-are-regulated-by-hypoxia-inducible-factors-1-alpha-hif-1a-to-protect-against-ischemic-injury-in-mouse-and-human-liver-transplantation/. Accessed November 21, 2024.

« Back to 2022 American Transplant Congress