Insulin-like growth factor-1 expression in reflux nephropathy

Area of Science:

• Nephrology
• Pediatric Nephrology
• Molecular Biology

Background:

• Reflux nephropathy (RN) is a primary cause of end-stage renal failure in children and young adults.
• Insulin-like growth factor-1 (IGF-1) and its receptor (IGF-1R) are present in renal tubular cells and can promote cell survival.
• Exogenous IGF-1 has demonstrated protective effects on tubular cells following kidney injury.

Purpose of the Study:

• To investigate the expression of IGF-1 and IGF-1R in pediatric patients with reflux nephropathy.
• To correlate IGF-1 and IGF-1R expression levels with tubulointerstitial fibrosis and tubular apoptosis in RN.

Main Methods:

• Kidney specimens from 15 children with RN and control adult kidneys were analyzed.
• Immunofluorescence histochemistry was used to assess IGF-1 and IGF-1R protein expression.
• In situ hybridization (ISH) evaluated gene expression, while TUNEL assays measured tubular apoptosis and vimentin/clusterin assessed fibrosis.

Main Results:

• IGF-1 and IGF-1R immunoreactivity and mRNA expression were significantly reduced in RN kidneys compared to normal controls.
• RN kidneys showed increased expression of vimentin and clusterin, indicating tubulointerstitial fibrosis.
• Decreased IGF-1 and IGF-1R expression strongly correlated with increased tubular apoptosis in RN.

Conclusions:

• Downregulation of IGF-1 and IGF-1R appears to play a significant role in the pathogenesis of reflux nephropathy.
• This downregulation may contribute to RN by promoting tubular apoptosis and interstitial collagen deposition.