Abstract
Chronic kidney disease (CKD) is a global health problem associated with a number of comorbidities. Recent evidence implicates increased hemichannel-mediated release of adenosine triphosphate (ATP) in the progression of tubulointerstitial fibrosis, the main underlying pathology of CKD. Here, we evaluate the effect of danegaptide on blocking hemichannel-mediated changes in the expression and function of proteins associated with disease progression in tubular epithelial kidney cells. Primary human proximal tubule epithelial cells (hPTECs) were treated with the beta1 isoform of the pro-fibrotic cytokine transforming growth factor (TGFβ1) ± danegaptide. qRT-PCR and immunoblotting confirmed mRNA and protein expression, whilst a cytokine antibody array assessed the expression/secretion of proinflammatory and profibrotic cytokines. Carboxyfluorescein dye uptake and ATP biosensing measured hemichannel activity and ATP release, whilst transepithelial electrical resistance was used to assess paracellular permeability. Danegaptide negated carboxyfluorescein dye uptake and ATP release and protected against protein changes associated with tubular injury. Blocking Cx43-mediated ATP release was paralleled by partial restoration of the expression of cell cycle inhibitors, adherens and tight junction proteins and decreased paracellular permeability. Furthermore, danegaptide inhibited TGFβ1-induced changes in the expression and secretion of key adipokines, cytokines, chemokines, growth factors and interleukins. The data suggest that as a gap junction modulator and hemichannel blocker, danegaptide has potential in the future treatment of CKD.
Highlights
Chronic kidney disease (CKD) is a growing health concern associated with increased risk of cardiovascular disease and morbidity [1]
We identified that the predominant connexin isoform expressed in the proximal tubule, Cx43, is elevated in biopsy material isolated from individuals with diabetic nephropathy, an observation paralleled by increased hemichannel-mediated adenosine triphosphate (ATP) release in TGFβ1-treated primary proximal tubule cells [12]
The current study investigated the efficacy of danegaptide in negating connexinmediated hemichannel ATP release in primary TGFβ1-treated human proximal tubule epithelial cells, ahead of delineating its protective role against the expression and functional changes commonly associated with progression of tubulointerstitial fibrosis
Summary
Chronic kidney disease (CKD) is a growing health concern associated with increased risk of cardiovascular disease and morbidity [1]. Estimated to affect 10% of the global population [2], risk factors include age, diabetes, hypertension, dyslipidaemia and obesity [3]. Culminating in the loss of epithelial stability, persistent inflammation and increased deposition of the extracellular matrix [5,6], treatment of TIF and advanced CKD represents an unmet clinical need [3]. Altered connexin (Cx) expression and function have been implicated in the pathology of various forms of disease (as reviewed in [7]), including CKD (as reviewed in [8,9])
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