Collagen V-induced nasal tolerance downregulates pulmonary collagen mRNA gene and TGF-beta expression in experimental systemic sclerosis.

BACKGROUND: The purpose of this study was to evaluate collagen deposition, mRNA collagen synthesis and TGF-beta expression in the lung tissue in an experimental model of scleroderma after collagen V-induced nasal tolerance. METHODS: Female New Zealand rabbits (N = 12) were immunized with 1 mg/ml of collagen V in Freund's adjuvant (IM). After 150 days, six immunized animals were tolerated by nasal administration of collagen V (25 microg/day) (IM-TOL) daily for 60 days. The collagen content was determined by morphometry, and mRNA expressions of types I, III and V collagen were determined by Real-time PCR. The TGF-beta expression was evaluated by immunostaining and quantified by point counting methods. To statistic analysis ANOVA with Bonferroni test were employed for multiple comparison when appropriate and the level of significance was determined to be p < 0.05. RESULTS: IM-TOL, when compared to IM, showed significant reduction in total collagen content around the vessels (0.371 +/- 0.118 vs. 0.874 +/- 0.282, p < 0.001), bronchioles (0.294 +/- 0.139 vs. 0.646 +/- 0.172, p < 0.001) and in the septal interstitium (0.027 +/- 0.014 vs. 0.067 +/- 0.039, p = 0.026). The lung tissue of IM-TOL, when compared to IM, showed decreased immunostaining of types I, III and V collagen, reduced mRNA expression of types I (0.10 +/- 0.07 vs. 1.0 +/- 0.528, p = 0.002) and V (1.12 +/- 0.42 vs. 4.74 +/- 2.25, p = 0.009) collagen, in addition to decreased TGF-beta expression (p < 0.0001). CONCLUSIONS: Collagen V-induced nasal tolerance in the experimental model of SSc regulated the pulmonary remodeling process, inhibiting collagen deposition and collagen I and V mRNA synthesis. Additionally, it decreased TGF-beta expression, suggesting a promising therapeutic option for scleroderma treatment.

Ras activation is associated with vitamin D receptor mRNA instability in HC11 mammary cells.

HC11, a spontaneously immortalized murine mammary lineage maintains features of normal cells while HC11 H-ras transformed cells (HC11 ras) are tumorigenic. Ras transformation is associated with a lower Vitamin D receptor (VDR) mRNA content. Our goal was to investigate the mechanism underlying VDR mRNA differences between these cells. Although the VDR transcriptional rate measured by run-on assays did not differ between the cells, our data suggested a pos transcriptional mechanism involving higher VDR mRNA degradation in HC11 ras cells which was not due to mutations in its 3'-UTR region since sequences of mRNA obtained from HC11 and HC11 ras cells were identical. Treatment of HC11 ras cells with a farnesyltransferase inhibitor, which prevents ras activation, causing an enhancement of VDR mRNA levels, indicating an association between the ras signaling pathway and VDR mRNA instability. The present work suggests that the decreased mRNA levels in HC11 ras cells might in part be due to an early loss of stability.