TRANILAST AMELIORATES RENAL TUBULAR DAMAGE IN UNILATERAL URETERAL OBSTRUCTION:

Effect of Tranilast on Matrix Metalloproteinase-1 Secretion From Human Gingival Fibroblasts In Vitro

BACKGROUND

Some drugs such as phenytoin, calcium blockers, or cyclosporins are known to cause gingival fibrous hyperplasia, an unwanted side effect. Decreased collagen catabolism in overgrown gingival tissue has been proposed as one of the reasons causing the disease. The effect of tranilast, which suppresses collagen synthesis and cell proliferation, on matrix metalloproteinase (MMP-1) secretion from human gingival fibroblast, was studied in vitro.

METHODS

Human gingival fibroblasts were cultured from specimens taken from healthy, periodontal, and overgrown gingival tissues. The effects of tranilast on cell proliferation and MMP-1 secretion from gingival fibroblast were assessed. Inhibitory effect of transforming growth factor (TGF)-beta secretion from gingival fibroblast by tranilast was also evaluated.

RESULTS

Tranilast did not interfere with cell proliferation at the low concentrations. MMP-1 concentration significantly increased at the lower doses of tranilast up to about 2-fold compared to controls (P < 0.05). In contrast, higher doses of tranilast significantly decreased activity to 30% and 20%, respectively. MMP-1 secretion was inhibited significantly by phenytoin, nifedipine, and cyclosporin A and the depressed MMP-1 recovered to the control level with tranilast. The amount of secretion from normal and periodontitis gingival fibroblast specimens did not differ, but that from the overgrown gingiva was significantly less than the other types. Moreover, TGF-beta secretion was significantly inhibited by 300 microM of tranilast.

CONCLUSIONS

Tranilast upregulates the expression of type 1 collagenase suppressed by gingival overgrowth-inducing drugs, and inhibits TGF-beta secretion from gingival fibroblasts. Therefore, tranilast could be considered as an agent for controlling gingival over-growth.

Intervention with Tranilast Attenuates Renal Pathology and Albuminuria in Advanced Experimental Diabetic Nephropathy

<i>Background/Aims:</i> Tubulointerstitial pathology with the accumulation of extracellular matrix are pathological hallmarks of diabetic nephropathy that are directly related to declining renal function. Tranilast (N-[3,4-dimethoxycinnamoyl]anthranilic acid), an inhibitor of transforming growth factor-β (TGF-β), used to treat hypertrophic scars has recently been shown in pilot studies to exert a beneficial effect in advanced diabetic nephropathy in humans. However, its effects on diabetic renal pathology are unknown. <i>Methods:</i> Studies were conducted using a transgenic model, the diabetic (mRen-2)27 rat, which develops many of the structural and functional characteristics of human diabetic nephropathy when diabetes is induced with streptozotocin (STZ). An experimental design was chosen to mimic, in part, the clinical context with drug therapy (tranilast 400 mg/kg/ day) initiated in established disease (8 weeks after STZ) and in the presence of persistent hyperglycaemia and hypertension. <i>Results:</i> At 16 weeks, diabetes was associated with progressive albuminuria, tubulointerstitial fibrosis and tubular atrophy. Without affecting blood pressure or blood glucose, tranilast treatment was associated with a 83% reduction in tubulointerstitial fibrosis (p < 0.001), a 58% reduction in tubular atrophy (p < 0.01) and near normalization of albuminuria (p < 0.05) in diabetic Ren-2 rats. In vitro studies in primary cultures of human renal cortical fibroblasts demonstrated a reduction in TGF-β-induced hydroxyproline incorporation and fibronectin synthesis with tranilast 100 µ<i>M</i>. <i>Conclusion:</i> Tranilast, when administered during the course of experimental diabetic nephropathy, attenuates tubulointerstitial pathology and albuminuria. These findings are consistent with the antagonist effects of tranilast on TGF-β actions in the diabetic kidney.