Tranilast attenuates connective tissue growth factor-induced extracellular matrix accumulation in renal cells

• Published in: Kidney international Vol. 69; no. 6; pp. 989 - 995
• Main Authors: Qi, W., Chen, X., Twigg, S., Polhill, T.S., Gilbert, R.E., Pollock, C.A.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01-03-2006; Nature Publishing; Elsevier Limited
• Subjects: Anti-Allergic Agents - pharmacology; Biological and medical sciences; Blotting, Western; Cell Survival; Cells, Cultured; Collagen Type IV - analysis; Collagen Type IV - metabolism; Connective Tissue Growth Factor; cortical fibroblasts; CTGF; ECM; Extracellular Matrix - chemistry; Extracellular Matrix - drug effects; Extracellular Matrix - metabolism; Fibroblasts - drug effects; Fibroblasts - metabolism; Fibroblasts - pathology; Fibronectins - analysis; Fibronectins - metabolism; Fibrosis; Gene Expression Regulation - drug effects; Humans; Hypertrophy - pathology; Immediate-Early Proteins - genetics; Immediate-Early Proteins - physiology; Intercellular Signaling Peptides and Proteins - genetics; Intercellular Signaling Peptides and Proteins - physiology; Kidney Cortex - drug effects; Kidney Cortex - metabolism; Kidney Cortex - pathology; Kidney Tubules, Proximal - drug effects; Kidney Tubules, Proximal - metabolism; Kidney Tubules, Proximal - pathology; Medical sciences; Nephrology. Urinary tract diseases; ortho-Aminobenzoates - pharmacology; Phosphorylation; proximal tubular cells; pSmad2; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - analysis; Signal Transduction - physiology; Smad2 Protein - analysis; Smad2 Protein - physiology; TGF-β1; Transforming Growth Factor beta - pharmacology; Transforming Growth Factor beta - physiology; Transforming Growth Factor beta1; TGF-β1; proximal tubular cells; pSmad2; ECM; cortical fibroblasts; CTGF; Proximal; Nephrology; Connective tissue growth factor; Antihistaminic; Accumulation; Kidney; Urology; Tranilast; Renal tubule; Urinary system; Extracellular matrix; Antagonist; Transforming growth factor β1; H1 Histamine receptor; Fibroblast
• DOI: 10.1038/sj.ki.5000189
• EISSN: 1523-1755
• ISSN: 0085-2538

Tranilast (N-[3,4-dimethoxycinnamoyl]anthranilic acid) is a synthetic compound that we have recently reported to inhibit transforming growth factor-β1 (TGF-β1)-induced tubulointerstitial fibrosis in the kidney. Connective tissue growth factor (CTGF) is recognized as a potent downstream mediator of TGF-β1. Both proximal tubule cells (PTCs) and cortical fibroblasts (CFs) are considered to be responsible for the production of tubulointerstitial extracellular matrix (ECM). These studies were undertaken to assess the profibrotic effects of CTGF in an in vitro model of the human PTCs and CFs, and to determine whether tranilast is effective in limiting the in vitro matrix responses induced by CTGF. Primary cultures of PTCs and CFs were exposed to CTGF (20 ng/ml)±tranilast (100 μM). Cell hypertrophy and the secretion of the ECM proteins fibronectin and collagen IV were determined. The effects of tranilast on TGF-β1-induced CTGF mRNA expression and on phosphorylation of Smad2 were determined. CTGF significantly induced cell hypertrophy, increased fibronectin, and collagen IV secretion in PTCs and CFs. In all cases, the CTGF-induced increase in ECM protein was inhibited in the presence of tranilast. Tranilast reduced CTGF mRNA and phosphorylation of Smad2, which were induced by TGF-β1 in PTCs and CFs. These results suggest that tranilast is a potential effective antifibrotic compound in the kidney, exerting its effects via inhibition of TGF-β1-induced CTGF expression and downstream activation of the Smad2 pathway in both PTCs and CFs.