Cathepsin B Mediated Degradation of Jejunal Epithelial Tight Junction Proteins during the Early Stage of Hemorrhagic Shock

Abstract

Hemorrhagic shock has been strongly linked to intestinal permeability — a hallmark of intestinal epithelial barrier breakdown — whose increase is associated with reduced function of intercellular adhesion proteins. The early effects of hemorrhagic shock (HS) on junctional epithelial proteins and the potential mechanisms of increased intestinal permeability have not been fully investigated. We investigate three junctional proteins responsible for epithelial cell adhesion in the jejunum: Claudin‐3, Occludin, and E‐Cadherin. We also investigate the role of Cathepsin B, an epithelial lysosomal cysteine protease, in the degradation of those adhesion protein. We hypothesize that Cathepsin B cleaves the extracellular domain of the adhesion molecules in HS. 16 Sprague‐Dawley rats were divided into 4 groups of 4 animals: Control, HS (MAP = 35mmHg for 30 min without blood volume reconstitution), HS with enteral pre‐treatment by Golytely as a fluid carrier, and HS with enteral pre‐treatment by Golytely and CA074 (Cathepsin B inhibitor at 15mg/kg). Jejunum was collected for Western Blot and immunohistochemistry of Claudin‐3, Occludin, and E‐Cadherin. Both Western Blot and immunohistochemistry results showed a decrease in levels of Claudin‐3 (HS p‐value: 0.052; HS with Golytely p‐value: 0.026), Occludin (HS p‐value: 0.011; HS with Golytely p‐value: 0.0036), and E‐Cadherin (HS p‐value: 0.013; HS with Golytely p‐value: 0.00137) in HS and HS pretreated with Golytely groups when compared to Control. Addition of Cathepsin B inhibitor resulted in maintenance of junctional proteins in the jejunum after HS. These results indicate that active Cathepsin B is released early during HS and causes a reduction of cell‐cell adhesion proteins Claudin‐3, Occludin, and E‐Cadherin, leading to increased intestinal permeability.Support or Funding InformationNIH Grant: GM 85072