Kiwifruit cysteine protease actinidin compromises the intestinal barrier by disrupting tight junctions

• Published in: Biochimica et biophysica acta Vol. 1860; no. 3; pp. 516 - 526
• Main Authors: Grozdanovic, Milica M., Čavić, Milena, Nešić, Andrijana, Andjelković, Uroš, Akbari, Peyman, Smit, Joost J., Gavrović-Jankulović, Marija
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.03.2016
• Subjects: Actinidia - immunology; Actinidin; allergens; Amino Acid Sequence; animal models; Animals; blood serum; Caco-2 Cells; confocal microscopy; Cysteine Endopeptidases - pharmacology; Cysteine protease; cysteine proteinases; food allergies; Food Hypersensitivity - etiology; human cell lines; Humans; intestinal mucosa; Intestinal permeability; Intestines - drug effects; Intestines - metabolism; kiwifruit; Mice; Mice, Inbred BALB C; Molecular Sequence Data; Occludin; Occludin - metabolism; occludins; Permeability; plant-based foods; proteolysis; Tight junctions; Tight Junctions - drug effects; LDH; Actinidin; Cysteine protease; Tight junctions; ZO; EL; Intestinal permeability; TEER; TJs; MALT; Occludin
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/j.bbagen.2015.12.005

The intestinal epithelium forms a barrier that food allergens must cross in order to induce sensitization. The aim of this study was to evaluate the impact of the plant-derived food cysteine protease — actinidin (Act d1) on the integrity of intestinal epithelium tight junctions (TJs). Effects of Act d1 on the intestinal epithelium were evaluated in Caco-2 monolayers and in a mouse model by measuring transepithelial resistance and in vivo permeability. Integrity of the tight junctions was analyzed by confocal microscopy. Proteolysis of TJ protein occludin was evaluated by mass spectrometry. Actinidin (1mg/mL) reduced the transepithelial resistance of the cell monolayer by 18.1% (after 1h) and 25.6% (after 4h). This loss of barrier function was associated with Act d 1 disruption of the occludin and zonula occludens (ZO)-1 network. The effect on intestinal permeability in vivo was demonstrated by the significantly higher concentration of 40kDa FITC-dextran (2.33μg/mL) that passed from the intestine into the serum of Act d1 treated mice in comparison to the control group (0.5μg/mL). Human occludin was fragmented, and putative Act d1 cleavage sites were identified in extracellular loops of human occludin. Act d1 caused protease-dependent disruption of tight junctions in confluent Caco-2 cells and increased intestinal permeability in mice. In line with the observed effects of food cysteine proteases in occupational allergy, these results suggest that disruption of tight junctions by food cysteine proteases may contribute to the process of sensitization in food allergy. [Display omitted] •Actinidin caused protease-dependent disruption of tight junctions in confluent Caco-2 cells.•Actinidin caused increased intestinal permeability in mice.•Putative actinidin cleavage sites are identified in extracellular loops of human occludin.•Food cysteine proteases may contribute to the sensitization in food allergy.