ER stress preconditioning ameliorates liver damage after hemorrhagic shock and reperfusion

David Peter Obert; Alexander Karl Wolpert; Nathan Lewis Grimm; Sebastian Korff

doi:10.3892/etm.2021.9679

ER stress preconditioning ameliorates liver damage after hemorrhagic shock and reperfusion

Exp Ther Med. 2021 Mar;21(3):248. doi: 10.3892/etm.2021.9679. Epub 2021 Jan 22.

Authors

David Peter Obert^{1

2}, Alexander Karl Wolpert^{2

3}, Nathan Lewis Grimm⁴, Sebastian Korff^{2

5}

Affiliations

¹ Department of Anesthesiology and Intensive Care, School of Medicine, Technical University of Munich, 81675 Munich, Germany.
² Department of Trauma Surgery, University of Heidelberg, 69118 Heidelberg, Germany.
³ Department of Trauma Surgery, Paracelsus Medical University, 90471 Nuremberg, Germany.
⁴ Department of Orthopaedic Surgery, Duke University Medical Center, Durham, NC 27708, USA.
⁵ Department of Orthopaedic Surgery, Klinikum rechts der Isar, Technical University of Munich, 81675 Munich, Germany.

Abstract

The mismatch of oxygen supply and demand during hemorrhagic shock disturbs endoplasmic reticulum (ER) homeostasis. The resulting accumulation of unfolded proteins in the ER lumen, which is a condition that is defined as ER stress, triggers the unfolded protein response (UPR). Since the UPR influences the extent of organ damage following hemorrhagic shock/reperfusion (HS/R) and mediates the protective effects of stress preconditioning before ischemia-reperfusion injury, the current study investigated the mechanisms of ER stress preconditioning and its impact on post-hemorrhagic liver damage. Male C56BL/6-mice were injected intraperitoneally with the ER stress inductor tunicamycin (TM) or its drug vehicle 48 h prior to being subjected to a 90 min pressure-controlled hemorrhagic shock (30±5 mmHg). A period of 14 h after hemorrhagic shock induction, mice were sacrificed. Hepatocellular damage was quantified by analyzing hepatic transaminases and hematoxylin-eosin stained liver tissue sections. Additionally, the topographic expression patterns of the ER stress marker binding immunoglobulin protein (BiP), UPR signaling pathways, and the autophagy marker Beclin1 were evaluated. TM injection significantly increased BiP expression and modified the topographic expression patterns of the UPR signaling proteins. In addition, immunohistochemical analysis of Beclin1 revealed an increased pericentral staining intensity following TM pretreatment. The histologic analysis of hepatocellular damage demonstrated a significant reduction in cell death areas in HS/R+TM (P=0.024). ER stress preconditioning influences the UPR and alleviates post-hemorrhagic liver damage. The beneficial effects were, at least partially, mediated by the upregulation of BiP and autophagy induction. These results underscore the importance of the UPR in the context of HS/R and may help identify novel therapeutic targets.

Keywords: binding immunoglobulin protein; hemorrhage; ischemia-reperfusion injury; tunicamycin; unfolded protein response.