Irsogladine maleate regulates gap junctional intercellular communication-dependent epithelial barrier in human nasal epithelial cells

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

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.

Irsogladine maleate alters expression of a tight junction protein in portal hypertensive gastropathy

BACKGROUND AND AIM

Portal hypertensive gastropathy (PHG) is characterized by noninflammatory edema and vasodilatation of the lamina propria of the mucosal epithelium. In addition, the alterations of intercellular junction proteins and dilatation of the endothelial gaps have been reported. In this study, we examined whether irsogladine maleate (IM), a gastric mucosal protective agent, has the potential to improve PHG by restoration of tight junctions (TJs).

METHODS

Twenty-four patients with PHG were registered and randomly assigned into two groups: 12 patients in the IM-administration group and 12 patients in the non-administration group. In the administration group, IM (4 mg/day) was administered orally for 12 weeks. Gastric mucosa with a red color in patients with PHG were obtained endoscopically on the registration day and 12 weeks later. The endoscopic findings were evaluated, an immunohistochemical analysis of claudin-3 (a TJ protein) expression in gastric mucosal tissues by a laser microscope was performed, and claudin-3 expression was quantified by western blot analysis.

RESULTS

Irsogladine maleate improved the degree of PHG in 2/12 patients endoscopically, in contrast to none of the 12 patients in the non-administration group. Immunohistochemical analysis showed that expression of claudin-3 increased in 8/12 patients in the IM-administration group and 2/12 patients in the non-administration group (P = 0.036). Western blot analysis revealed that the increase in claudin-3 after 12 weeks was significantly higher in the IM-administration group than in the non-administration group (P = 0.010).

CONCLUSIONS

The present pilot study suggested that IM might improve the gastric mucosa in PHG through restoration of TJ-protein claudin-3.