The effects of sugar phosphates in reducing hif-1? Under hypoxic conditions

Preliminary research has shown evidence of the presence of connective tissue growth factor CTGF in the tenosynovium of patients with carpal tunnel syndrome, a finding which supports the fibrotic pathophysiological progression of the disease. Connective tissue growth factor (CTGF) expression is regulated through the actions of two distinct molecular signals; transforming growth factor-beta (TGF-ß) and hypoxia inducible factor-1 alpha (HIF-1a). Mannose-6 phosphate is a natural inhibitor of TGF-ß and can also is converted to fructose 6 phosphate which we have shown is capable of reducing HIF-1 a. The goal of this experiment was to determine if mannose 6 phosphate is capable of reducing HIF-1a reducing both components of the CTGF pathway. Fibroblast cells were subjected to 5µM or 50µM concentration of either fructose 1,6 diphosphate (F6P) or mannose 6 phosphate (M6P) for a period of 24 hours in either ambient or hypoxic conditions. After the incubation period, cell viability, cell damage, morphology, and concentration of HIF-1a were determined. Cell numbers were reduced by approximately 50% in hypoxic conditions compared with ambient control. Intracellular glutathione concentration was increased significantly under hypoxic conditions compared with control. The concentration of reduced glutathione in both F6P and M6P were similar to ambient air values indicating a protection against oxidative stress. Hypoxia inducible factor-1 alpha was increased in cells under hypoxic conditions compared to base line levels in normoxic treated cells. Interestingly, only 5µM F6P was able to reduce HIF-1a back toward control normoxic values. The data suggest that the HIF-1a pathway leading to fibrosis is not the primary pathway for reductions in CTGF following MP6 treatments. This information is important in terms of developing compounds which decrease adhesion while not decreasing cell viability or impairing cellular function.