<p>In respiratory airway epithelial cells, lipopolysaccharide (LPS) treatment induced an enhancement of connexin 26 (Cx26) hemichannel activity shown by dye uptake experiments after siRNA-mediated knock-down of Cx26. This effect was already observed at infection relevant concentrations (≤ 10 ng/mL LPS) and involved tumor necrosis factor alpha (TNF-α)- and Ca<sup>2+</sup>-dependent signaling. High concentrations (1&#xa0;µg/mL LPS) reduced the transepithelial electrical resistance (TEER) of Calu-3 cells by 35% within an application time of 3&#xa0;h followed by a recovery. Parallel to barrier alteration, a reduced tight junction organization rate (TiJOR) of claudin-4 (CLDN4) by 75% was observed within an application time of 3&#xa0;h. After TEER recovery, CLDN4 TiJOR stayed reduced. Low concentrations (10 ng/mL LPS) required three times repeated application for barrier reduction and CLDN4 TiJOR reduction by 30%. The small molecule CVB4-57, newly published as a potential inhibitor of Cx26 hemichannels, mitigated the effects of LPS on the epithelial barrier function. Molecular docking studies revealed a potential interaction between CVB4-57 and Cx26 thereby reducing its hemichannel activity. We conclude that LPS-related enhancement of Cx26 hemichannel activity acts like a “molecular scar” that weakens the lung epithelium, which could be attenuated by agents targeting Cx26 hemichannels.</p>

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Repression of Connexin26 hemichannel activity protects the barrier function of respiratory airway epithelial cells against LPS-induced alteration

  • Tina Lehrich,
  • Anne Dierks,
  • Masina Plenge,
  • Helena Obernolte,
  • Klaudia Grieger,
  • Katherina Sewald,
  • Frederic Rodriguez,
  • Lucie Malet,
  • Peter Braubach,
  • Florence Bedos-Belval,
  • Anaclet Ngezahayo

摘要

In respiratory airway epithelial cells, lipopolysaccharide (LPS) treatment induced an enhancement of connexin 26 (Cx26) hemichannel activity shown by dye uptake experiments after siRNA-mediated knock-down of Cx26. This effect was already observed at infection relevant concentrations (≤ 10 ng/mL LPS) and involved tumor necrosis factor alpha (TNF-α)- and Ca2+-dependent signaling. High concentrations (1 µg/mL LPS) reduced the transepithelial electrical resistance (TEER) of Calu-3 cells by 35% within an application time of 3 h followed by a recovery. Parallel to barrier alteration, a reduced tight junction organization rate (TiJOR) of claudin-4 (CLDN4) by 75% was observed within an application time of 3 h. After TEER recovery, CLDN4 TiJOR stayed reduced. Low concentrations (10 ng/mL LPS) required three times repeated application for barrier reduction and CLDN4 TiJOR reduction by 30%. The small molecule CVB4-57, newly published as a potential inhibitor of Cx26 hemichannels, mitigated the effects of LPS on the epithelial barrier function. Molecular docking studies revealed a potential interaction between CVB4-57 and Cx26 thereby reducing its hemichannel activity. We conclude that LPS-related enhancement of Cx26 hemichannel activity acts like a “molecular scar” that weakens the lung epithelium, which could be attenuated by agents targeting Cx26 hemichannels.