Effect of advanced glycation end products, extracellular matrix metalloproteinase inducer and matrix metalloproteinases on type-I collagen metabolism

The aim of the study was to examine the association among advanced glycation end products (AGEs), extracellular matrix metalloproteinase inducer (EMMPRIN) and matrix metalloproteinase (MMPs), and investigate whether AGEs affect type I collagen (COL-I) through EMMPRIN or MMPs. A co-culture system with the osteoblast-like cells (MC3T3E1) and mouse RAW264.7 cells was employed to examine the effects of AGE-bovine serum albumin (BSA) (50 mg/l), EMMPRIN antibody (5 mg/l) and AGE-BSA+EMMPRIN antibody separately on COL-I expression for 24 h. Culture media were analyzed for the content of COL-I by ELISA. The effect of different concentrations of AGE-BSA (0, 50, 100, 200 and 400 mg/l) for 24 h was assessed on COL-I levels. Finally, semiquantitative RT-PCR was used to detect the osteoblast COL-I mRNA expression and MMP-2 and MMP-9's PMAO were also measured in the culture medium. COL-I content in the culture medium decreased significantly following treatment with AGE-BSA (P<0.05). EMMPRIN antibody increased COL-I content (P<0.05). EMMPRIN antibody+AGE-BSA increased COL-I significantly (P<0.05). Different concentrations of AGE-BSA increased COL-I mRNA expression significantly compared with the control group (P<0.05), and were enhanced with increasing AGE-BSA concentration (P<0.05). Also MMP-2 and MMP-9 secretion increased significantly (P<0.05), with the increasing AGE-BSA concentration. In conclusion, an increase in AGE levels in vitro stimulates the secretion of EMMPRIN/MMPs, promotes the degradation of COL-I and reduces bone strength.