KCNJ2 overexpression induces pro-inflammatory cytokine production, impaired barrier function and acantholysis in esophageal epithelial cells

Rationale: Inward rectifying potassium channel KCNJ2 is upregulated in the epithelium of eosinophilic esophagitis (EoE) patients compared to healthy controls.  However, whether KCNJ2 contributes to GI Th2 inflammation and epithelium barrier impairment in EoE is unknown.

Methods: We employed the EPC2 human esophageal epithelial cell line to determine if KCNJ2 induces EoE-like changes. Chemokine and cytokine productions (at mRNA and protein levels) were examined in empty vector and KCNJ2 overexpressing EPC2 cells following exposure to IL-13, Poly I:C and allergen. Esophageal barrier function was tested by TEER-measuring air-liquid-interface (ALI) culture of EPC2 cells.

Results: Following IL-13 stimulation, KCNJ2 overexpression increases CCL26 (eotaxin-3) production by 3.2 fold compared to empty vector (EV) controls (P<0.05). Additionally, KCNJ2 overexpression increases the IL-13 induced barrier impairment by 45% compared to EV controls (P<0.05). With a Poly I:C stimulation, KCNJ2 overexpressing EPC2 cells produce 15-fold more TSLP mRNA and 3.4-fold more protein compared to EV controls (P<0.001).  Likewise, KCNJ2 overexpressing cells produced increased mRNA for IL-8 (6-fold, P<0.01), GM-CSF (14-fold, P<0.01) and IFN-β (6-fold, P<0.01). Finally, KCNJ2 overexpressing cells produced 23-fold higher CCL26 mRNA compared with unstimulated controls following exposure to Aspergillus fumigatus extract (50ug/mL, 24 hours) in contrast to 3-fold increase in EV controls. Moreover, allergen exposure induced acantholysis exclusively in KCNJ2 overexpressing cells.

Conclusions:   KCNJ2 overexpression is sufficient to induce pro-EoE like changes in esophageal epithelial cells including pro-inflammatory cytokine production, impaired barrier function and acantholysis.  As such, we propose that over-expression of KCNJ2 has a potential causative role in EoE.