Rapamycin at subimmunosuppressive levels inhibits mesangial cell proliferation and extracellular matrix production

Area of Science:

• Nephrology
• Cell Biology
• Pharmacology

Background:

• Mesangioproliferative diseases involve abnormal mesangial cell proliferation.
• Rapamycin has demonstrated antiproliferative effects.
• Previous studies on rapamycin's effects on mesangial cells used high doses and did not fully elucidate the mechanism of action.

Purpose of the Study:

• To investigate the effects of low-dose rapamycin on mesangial cell proliferation.
• To explore the underlying mechanism of action of low-dose rapamycin in mesangial cells.

Main Methods:

• Primary cultures of mouse mesangial cells were treated with varying concentrations of rapamycin.
• Cell proliferation, DNA synthesis, apoptosis, type IV collagen production, and p70S6K phosphorylation were assessed.

Main Results:

• A rapamycin concentration of 0.1 ng/ml decreased mesangial cell number and DNA synthesis without affecting apoptosis.
• Type IV collagen protein production was inhibited at 0.01 ng/ml rapamycin, while gene expression remained unchanged.
• P70S6K phosphorylation was dose-dependently inhibited at 0.1 ng/ml rapamycin, correlating with reduced cell proliferation.

Conclusions:

• Low-dose rapamycin (0.1 ng/ml) inhibits mesangial cell proliferation and p70S6 kinase phosphorylation.
• A lower concentration (0.01 ng/ml) impacts type IV collagen production.
• Further in vivo studies are warranted to explore low-dose rapamycin for treating mesangioproliferative glomerulonephritis.