Direct effects of simvastatin on proliferation and matrix accumulation in cultured murine mesangial cells

Determination of simvastatin-induced changes in bone composition and structure by Fourier transform infrared spectroscopy in rat animal model

Simvastatin is a hypolipidemic drug which is used to control hypercholesterolemia and to prevent cardiovascular disease. In the current study, the effects of high and low doses of simvastatin treatment on tibia of healthy rats were investigated. Wistar rats were used for the control, 20mg and 50mg simvastatin-treated groups. Molecular investigations were performed using Fourier transform infrared spectroscopy. In the bones of the two groups of simvastatin-treated rats, the relative mineral/matrix ratio (p<0.001), relative carbonate content (p<0.001), carbonate/amide I ratio (p<0.001) and crystallinity (p<0.001) decreased significantly compared to the control group. Low dose of simvastatin treatment is more effective in reducing the relative carbonate content indicating the amount of carbonate substitution for phosphate in the mineral crystal. The olefinic band almost disappeared in the high dose of simvastatin-treated group which implies a decrease in unsaturation and an increase in lipid peroxidation. The higher frequency value and the bandwidth of CH(2) asymmetric stretching band for the 50mg treated group imply more disordered (p<0.001) and fluid (p<0.001) membrane structure. Low dose of simvastatin is more effective in strengthening the bone than high dose simvastatin treatment. High dose simvastatin treatment induces lipid peroxidation and changes the lipid composition and concentration, which are known to affect membrane physical properties.

Suppressive mechanisms of Sairei-to on mesangial matrix expansion in rat mesangioproliferative glomerulonephritis

BACKGROUND

Sairei-to (TJ-114) is a Japanese herbal medicine of standardized quality, originating from traditional Chinese medicine. In the present in vivo study, we investigated the suppressive effects of TJ-114 and related drugs, Shosaiko-to (TJ-9), and Saiboku-to (TJ-96), on mesangioproliferative glomerulonephritis (MsPGN) in rats. TJ-9 is a basal prescription of TJ-96 and TJ-114. We evaluated the efficacy of these drugs on proteinuria, extracellular matrix (ECM) accumulation, and superoxide dismutase (SOD)-activity.

METHODS

MsPGN in Wistar rats was induced by intravenous injection of rabbit anti-rat thymocyte serum (ATS). TJ-114, TJ-9, TJ-96 (500 mg/kg/day), or prednisolone (PSL, 2 mg/kg/day) was orally administered to the rats as drinking water from the day of ATS injection (day 0) to day 8, when rats were sacrificed and the kidney specimens were collected. Macrophage infiltration was evaluated by immunostaining for ED-1. ECM was measured by trichrome-staining, and fibronectin immunostaining. Northern blotting was performed to clarify the mRNA expression of cytokines and fibronectin. SOD-activity in the homogenate of renal cortex was also evaluated.

RESULTS

The amount of urinary protein was significantly decreased only in the TJ-114-treated group compared with the disease control group (p < 0.05). The number of ED-1-positive cells was significantly decreased in all the treatment groups (p < 0.05, respectively). Decreases in the trichrome-stained area were observed moderately in the TJ-114-treated group (66% of control, p < 0.001) and mildly in the PSL-treated group (76% of control, p < 0.001). The staining area of fibronectin in the glomerulus was significantly decreased in all the treated groups except PSL, and was especially suppressed in the TJ-114-treated group (45% of control, p < 0.001). Transforming growth factor (TGF) and connective tissue growth factor (CTGF) expression significantly decreased in the TJ-114-treated group to the control level (p < 0.05). TGF-beta, CTGF, and fibronectin mRNA were upregulated in the disease control group, and TJ-114 suppressed these mRNA expressions in glomeruli. The SOD-activity of renal cortex-homogenate was significantly augmented in all the treated groups except PSL, markedly in the TJ-96- and TJ-114-treated groups.

CONCLUSION

These results suggest that TJ-114 ameliorates ECM accumulation in experimental rat MsPGN, partly suppressing TGF-beta and CTGF expression through the recovery of SOD-activity.

Coagulation in the mesangial area promotes ECM accumulation through factor V expression in MsPGN in rats

It is well known that tissue factor starts the extrinsic coagulation pathway, which activates factor X to Xa, and factor V is a membrane-bound potent cofactor for the terminating stage of prothrombin activation by factor Xa. In a previous in vitro study, factor V was induced in cultured mesangial cells by inflammatory stimulation and increased expression of factor V promoted fibrin generation on the cultured mesangial cell surface. We report that extracellular matrix (ECM) accumulation is increased in association with coagulation in the mesangial area through factor V expression in mesangioproliferative glomerulonephritis (MsPGN). Wistar rats were intravenously injected with rabbit anti-rat thymocyte serum accompanied with or without simultaneous injection of rabbit anti-factor V antibody. Time course study in immunohistochemistry revealed that factor V expression was prominent on day 3 and fibrin-related antigen (FRA) deposition, then ECM accumulation, followed from day 3 to day 8. Massive fibronectin depositions and transforming growth factor (TGF)-β expression were also noted in glomeruli from the disease control group, markedly higher than those in the normal group, and these depositions and expressions were significantly decreased in the anti-factor V neutralizing antibody-injected group. Northern blot analysis revealed that factor V mRNA expression was prominent on day 3 and was weak on day 8. Double-labeling experiments revealed the frequent colocalization of α-smooth muscle actin with factor V, FRA, and fibronectin in the same mesangial areas of glomeruli. TGF-β, connective tissue growth factor (CTGF), collagen type IV, and fibronectin mRNA were upregulated in the disease control group, and anti-factor V-neutralizing antibody injection suppressed these mRNA expressions in glomeruli. The present results suggest that ECM components accumulation may progress in accordance with coagulation in the mesangial area through mesangial factor V expression and upregulated expression of TGF-β and CTGF in MsPGN.