Objective: Transforming growth factor (TGF)-beta is a critical factor in the progression of renal injury, regardless of the primary etiology. Such injury is characterized by glomerular sclerosis and tubulointerstitial fibrosis. To develop a ribozyme-based therapy for progressive renal diseases, we examined the effects of chimeric DNA-RNA hammerhead ribozyme targeting TGF-beta1 mRNA on glomerulosclerosis in salt-loaded, stroke-prone spontaneously hypertensive rats (SHR-SP) and salt-sensitive Dahl (Dahl-S) rats.
Methods: The chimeric DNA-RNA ribozyme to TGF-beta1 was delivered by polyethylenimine to cultured mesangial cells from SHR-SP in vitro and to glomeruli in SHR-SP in vivo. The chimeric ribozyme reduced expression of TGF-beta1 mRNA and protein, which was accompanied by inhibition of expression of extracellular matrix molecules such as fibronectin and collagen type I in mesangial cells from SHR-SP in vitro.
Results: One intraperitoneal injection of 200 microg of chimeric DNA-RNA ribozyme to TGF-beta1 in vivo markedly ameliorated thickening of capillary artery walls and glomerulosclerosis in salt-loaded SHR-SP and Dahl-S rats without a reduction in blood pressure. The chimeric ribozyme reduced expression of TGF-beta1 and connective tissue growth factor (CTGF) mRNAs in renal cortex in salt-loaded Dahl-S rats. Chimeric ribozyme to TGF-beta1 significantly reduced levels of protein in urine in the Dahl-S rats.
Conclusion: These results suggest that chimeric DNA-RNA ribozyme to TGF-beta1 may be useful as a gene therapy for progressive tissue injury in a wide variety of renal diseases, including hypertensive nephrosclerosis.