Effect of Toll-like receptor-2,-4,-5,-7, and NOD2 stimulation on potassium channel conductance in intestinal epithelial cells

Autores da FMUP

• Patrício Manuel Vieira Araújo Soares Da Silva

  Autor

• Fernando José Magro Dias

  Autor

Participantes de fora da FMUP

• Cosme, Dina

Unidades de investigação

• Biomedicina

• Laboratório Associado RISE- Rede de Investigação em Saúde

  

  Investigador

  Fernando Carlos De Landér Schmitt

• RISE-Health

  

  Investigador

  Fernando Carlos De Landér Schmitt

Abstract

Disproportionate activation of pattern recognition receptors plays a role in inflammatory bowel disease (IBD) pathophysiology. Diarrhea is a hallmark symptom of IBD, resulting at least in part from an electrolyte imbalance that may be caused by changes in potassium channel activity. We evaluated the impact of Toll-like receptors (TLRs) and nucleotide-binding oligomerization domain 2 (NOD2) stimulation on potassium conductance of the basolateral membrane in human intestinal epithelial cells (IECs) and the role of potassium channels through electrophysiological assays under short-circuit current in Ussing chambers. TLRs and NOD2 were stimulated using specific agonists, and potassium channels were selectively blocked using triarylmethane-34 (TRAM-34), adenylyl-imidodiphosphate (AMP-PNP), and BaCl2. Potassium conductance of the basolateral membrane decreased upon activation of TLR2, TLR4, and TLR7 in T84 cells (means +/- SE, -11.2 +/- 4.5, -40.4 +/- 7.2, and -19.4 +/- 5.9, respectively) and in Caco-2 cells (-13.1 +/- 5.7, -55.7 +/- 7.4, and -29.1 +/- 7.2, respectively). In contrast, activation of TLR5 and NOD2 increased basolateral potassium conductance, both in T84 cells (18.0 +/- 4.1 and 18.4 +/- 2.8, respectively) and in Caco-2 cells (21.2 +/- 8.4 and 16.0 +/- 3.6, respectively). TRAM-34 and AMP-PNP induced a decrease in basolateral potassium conductance upon TLR4 stimulation in both cell lines. Both K(Ca)3.1- and K(ir)6-channels appear to be important mediators of this effect in IECs and could be potential targets for therapeutic agent development. NEW & NOTEWORTHY This study highlights that PRRs stimulation directly influences K+-channel conductance in IECs. TLR-2, -4, -7 stimulation decreased K+ conductance, whereas TLR5 and NOD2 stimulation had the opposite effect, leading to an increase of it instead. This study reports for the first time that K(Ca)3.1- and K(ir)6-channels play a role in K+ transport pathways triggered by TLR4 stimulation. These findings suggest that K(Ca)3.1- and K(ir)6-channels modulation may be a potential target for new therapeutic agents in IBD.

Keywords

• intestinal epithelial cells; inflammatory bowel disease; potassium channel; nucleotide-binding oligomerization domain 2; Toll-like receptors