Long Term Effect of High Glucose and Phosphate Levels on the OPG/RANK/RANKL/TRAIL System in the Progression of Vascular Calcification in rat Aortic Smooth Muscle Cells

Osteoprotegerin (OPG), receptor activator of NF-kappaB ligand (RANKL)/receptor activator of NF-kappaB (RANK) axis, and TNF-related apoptosis-inducing ligand (TRAIL) participate in vascular calcification process including atherosclerosis, but their contributions under high glucose (HG) and phosphate (HP) condition for a long-term period (more than 2 weeks) have not been fully determined. In this study, we evaluated the effects of HG and HP levels over 2 or 4 weeks on the progression of vascular calcification in rat vascular smooth muscle cells (VSMCs). Calcium deposition in VSMCs was increased in medium containing HG (30 mmol/L D-glucose) with beta-glycerophosphate (beta-GP, 12 mmol/L) after 2 weeks and increased further after 4 weeks. OPG mRNA and protein expressions were unchanged in HG group with or without beta-GP after 2 weeks. However, after 4 weeks, OPG mRNA and protein expressions were significantly lower in HG group with beta-GP. No significant expression changes were observed in RANKL, RANK, or TRAIL during the experiment. After 4 weeks of treatment in HG group containing beta-GP and rhBMP-7, an inhibitor of vascular calcification, OPG expressions were maintained. Furthermore, mRNA expression of alkaline phosphatase (ALP), a marker of vascular mineralization, was lower in the presence of rhBMP-7. These results suggest that low OPG levels after long term HG and phosphate stimulation might reduce the binding of OPG to RANKL and TRAIL, and these changes could increase osteo-inductive VSMC differentiation, especially vascular mineralization reflected by increased ALP activity during vascular calcification.

Effect of Ultraviolet Irradiation on Bone Metabolism: Serologic & Radiological Study in Mouse / 대한정형외과연구학회지

PURPOSE: The purpose of this study was to investigate the effects of low energy-ultraviolet B (UVB) irradiation on bone metabolism and turnover in mice. MATERIALS AND METHODS: Five-week old C57BL/6 mice were randomly allocated into two groups. Control group (n=35) was not exposed to UVB and experimental group (n=35) was exposed to low energy-UVB for 30 min a day during 7 days. Serological and radiological examination was performed at 0, 1, 2, 4, 8 week(s) of each group (n=7). RESULTS: Analysis of biochemical bone markers revealed that alkaline phosphatase (ALP) was detected higher in the UVB group compared to control group. Serum level of osteocalcin was higher in UVB group at 1st week after UVB irradiation (p=0.031). The mean value of Vitamin D was significantly higher in UVB group than control group (p=0.032). Bone mineral density (BMD) from both 5th lumbar spine (p=0.124) and femur (p=0.862) showed higher in UVB group than control group from two weeks after irradiation, but they were not statistically significant. CONCLUSION: Our study with radiological bone mineral density and serological tests for biochemical bone turnover markers revealed that ultraviolet irradiation contributed positive effect on bone formation.

Effect of Interleukin-10 on Lipopolysaccahride/Interferon-gamma- Induced Chemokine Mig Gene Expression

Interferon-gamma (IFN-gamma) is well known as a potent inducer in monokine induced by IFN-gamma (Mig) mRNA expression. Although lipopolysaccharide (LPS) alone is weakly effective on Mig mRNA expression. the stimulation of LPS and IFN-gamma (LPS/IFN-gamma simultaneously has been shown to synergize to produce a high level of Mig mRNA in mouse peritoneal macrophages. In this study, interleukin-10 (IL-10) was found to suppress the LPS/IFN-gamma- induced Mig mRNA expression in cell type- and mouse strain-specific fashion, but IFN-gamma alone-induced Mig mRNA was unaffected by IL-10 under identical experimental conditions. The IL-10-mediated suppression of LPS/IFN-gamma-stimulated Mig mRNA expression was dependent on the concentration of IL-10, and was prevented when the agent was added 2 hours after LPS/IFN-gamma treatment. The suppressive action of IL-10 was dependent on a protein synthesis. However, IL-10 did not reduce the stability of LPS/IFN-gamma-induced Mig mRNA. These data may have important implications for a previously unrecognized role for IL-10 as a regulator of synergistic effect of LPS on the IFN-gamma-induced expression of the Mig gene in macrophages.