Suppression of renin-angiotensin gene expression in the kidney by paricalcitol

Area of Science:

• Nephrology
• Endocrinology
• Molecular Biology

Background:

• The renal renin-angiotensin system (RAS) is crucial in chronic kidney disease (CKD) progression.
• Vitamin D receptor (VDR) activators are known to slow experimental CKD.
• VDR activators can suppress RAS activity in non-renal organs.

Purpose of the Study:

• To investigate if paricalcitol's renoprotective effects in CKD are linked to suppressing renal RAS gene expression.
• To evaluate the impact of paricalcitol on key RAS components and related factors in a rat remnant kidney model.

Main Methods:

• Rats with 5/6 nephrectomy (remnant kidney model) were treated with two doses of paricalcitol thrice weekly for 8 weeks.
• Quantitative assessment of mRNA and protein levels for angiotensinogen, renin, renin receptor, angiotensin type 1 receptor, and vascular endothelial growth factor.
• Evaluation of renal function, proteinuria, hypertension, and kidney damage.

Main Results:

• Paricalcitol significantly reduced mRNA levels of angiotensinogen, renin, renin receptor, and vascular endothelial growth factor by 30-50% in remnant kidneys.
• Protein expression of renin, renin receptor, angiotensin type 1 receptor, and vascular endothelial growth factor was also significantly decreased.
• Both doses of paricalcitol markedly improved glomerular and tubulointerstitial damage, hypertension, proteinuria, and renal function deterioration.

Conclusions:

• Beneficial effects of VDR activators in experimental CKD are, in part, mediated by down-regulating the renal RAS.
• Paricalcitol demonstrates significant renoprotective effects by inhibiting the intrarenal RAS.
• Targeting the renal RAS with VDR activators represents a potential therapeutic strategy for CKD.