Effects of HMGB1 on Tricellular Tight Junctions via TGF-β Signaling in Human Nasal Epithelial Cells.

Kizuku Ohwada,Masuo Kondoh,Ryo Miyata,Kenichi Takano,Tsuyoshi Ohkuni,Masaya Nakano,Takayuki Kohno,Takumi Konno,Takashi Kojima,Takuya Kakuki

doi:10.3390/ijms22168390

Kizuku Ohwada, Masuo Kondoh + Show 8 more

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https://doi.org/10.3390/ijms22168390

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Abstract

The airway epithelium of the human nasal mucosa acts as a physical barrier that protects against inhaled substances and pathogens via bicellular and tricellular tight junctions (bTJs and tTJs) including claudins, angulin-1/LSR and tricellulin. High mobility group box-1 (HMGB1) increased by TGF-β1 is involved in the induction of nasal inflammation and injury in patients with allergic rhinitis, chronic rhinosinusitis, and eosinophilic chronic rhinosinusitis. However, the detailed mechanisms by which this occurs remain unknown. In the present study, to investigate how HMGB1 affects the barrier of normal human nasal epithelial cells, 2D and 2.5D Matrigel culture of primary cultured human nasal epithelial cells were pretreated with TGF-β type I receptor kinase inhibitor EW-7197 before treatment with HMGB1. Knockdown of angulin-1/LSR downregulated the epithelial barrier. Treatment with EW-7197 decreased angulin-1/LSR and concentrated the expression at tTJs from bTJs and increased the epithelial barrier. Treatment with a binder to angulin-1/LSR angubindin-1 decreased angulin-1/LSR and the epithelial barrier. Treatment with HMGB1 decreased angulin-1/LSR and the epithelial barrier. In 2.5D Matrigel culture, treatment with HMGB1 induced permeability of FITC-dextran (FD-4) into the lumen. Pretreatment with EW-7197 prevented the effects of HMGB1. HMGB1 disrupted the angulin-1/LSR-dependent epithelial permeability barriers of HNECs via TGF-β signaling in HNECs.

Highlights

The airway epithelium of the human nasal mucosa interacts with various environmental agents and acts as a physical barrier that protects against inhaled substances and pathogens via tight junctions (TJs) [1,2]
Immunocytochemistry showed expression of tricellular TJs (tTJ) molecules angulin-1/LSR and TRIC at both the areas of tricellular tight junctions and bicellular tight junctions in Human Nasal Epithelial Cells (HNECs) cultured with 10% FBS (Figure 1A)
EW-7197 prevented the disruption of the epithelial barrier and hyperpermeability induced by High mobility group box-1 (HMGB1) with the changes of TJ molecules, including angulin-1/LSR, in HNECs

Summary

Introduction

The airway epithelium of the human nasal mucosa interacts with various environmental agents and acts as a physical barrier that protects against inhaled substances and pathogens via tight junctions (TJs) [1,2]. TJs are intercellular junctions adjacent to the apical ends of paracellular spaces and have fence, barrier and signaling functions [8]. TJs are composed of claiudins (CLDNs), occludins (OCLN), JAMs and scaffold proteins such as ZO [9]. Angulin-1/lipolysis-stimulated lipoprotein receptor (LSR) and tricellulin (TRIC) seal the extracellular spaces where three epithelial cells come into contact and have various functions [10]. LSR recruits TRIC to tTJs, and both proteins are required for the full barrier function of epithelial cellular sheets [11]. In the human nasal epithelium, OCLN, JAM-A, ZO-1, ZO-2, CLDN-1, -4, -7, -8, -12, -13, -14 at bicellular TJs (bTj) and TRIC and angulin-1/LSR at tricellular TJs (tTJ) are detected on the surfaces of cells [1,2]

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