Calcitriol regulates angiotensin-converting enzyme and angiotensin converting-enzyme 2 in diabetic kidney disease

Area of Science:

• Nephrology
• Endocrinology
• Molecular Biology

Background:

• Diabetic nephropathy is a major complication of diabetes mellitus.
• The renin-angiotensin system, including angiotensin-converting enzyme (ACE) and ACE2, plays a critical role in diabetic nephropathy.
• Calcitriol's effects on ACE and ACE2 in this context are not fully understood.

Purpose of the Study:

• To investigate the impact of calcitriol on ACE and ACE2 expression in a rat model of diabetic nephropathy.
• To elucidate the role of mitogen-activated protein kinase (MAPK) pathways in calcitriol's renoprotective effects.

Main Methods:

• Streptozotocin-induced diabetic rats were treated with calcitriol for 16 weeks.
• Kidney tissues and rat renal tubular epithelial cells (NRK-52E) exposed to high glucose were analyzed for ACE, ACE2, and MAPK pathway activation.
• Specific MAPK inhibitors (SB203580, FR180204, SP600125) were used to assess pathway involvement.

Main Results:

• Calcitriol reduced proteinuria in diabetic rats without altering calcium-phosphorus metabolism.
• Diabetic conditions elevated the ACE/ACE2 ratio, which calcitriol treatment normalized by decreasing ACE and increasing ACE2.
• High glucose increased ACE via p38 MAPK and decreased ACE2 via ERK in renal cells; calcitriol inhibited both pathways.

Conclusions:

• Calcitriol exerts renoprotective effects in diabetic nephropathy by modulating tubular ACE and ACE2 levels.
• These effects appear to be mediated through the p38 MAPK and ERK signaling pathways.
• Calcitriol represents a potential therapeutic agent for managing diabetic kidney disease.