High glucose suppresses cathepsin activity in periodontal-ligament-derivedfibroblastic cells

The accumulation of extracellular matrices and integrins by high glucose ha s been reported in relation to diabetic complications. We previously report ed that PDL cells expressed a higher amount of VLA-5 when cultured in high- glucose (4500 mg/L) medium than those cultured in low-glucose (1100 mg/L) m edium. In this study, we aimed to address (1) whether this effect was media ted by the transcriptional level of the gene or the degradative level of th e protein, and (2) whether this effect was mediated by TGF-beta. The result s indicated that the level of mRNA encoding 015 integrin did not change in PDL cells regardless of the concentration of glucose. Alternatively, high g lucose suppressed cathepsin B+L activity. Additionally, the level of mRNA e ncoding TGF-beta was not affected by high glucose, nor did an anti-TGF-beta neutralizing antibody have an effect on the expression of beta 5 gene or c athepsin activity. Therefore, the effects of high glucose appeared to be me diated by impaired protein degradation, but not by autocrine TGF-beta.