An Immunohistochemical Study On HIF-1α And COX-2 In Human Dental Pulp

Objective: This study was to immunolocalize and assess the quantity of hypoxia inducible factor-1 alpha and cyclooxygenase-2 in human normal and inflammatory dental pulp. On this base,We would like to illustrate and assess the potential roles of HIF-1a and COX-2 in the physiological function of dental pulp and the pulp repair process following trauma or infection.Methods: Pulpal tissues were obtained from clinically extracted human healthy and inflammatory teeth .The 50 samples include 10 health pulps. 10 deep carious cases, 15 chronic pulpitis cases and 15 acute pulpitis cases (Four groups).The Streptaridin-Peroxidase Coiugated Method(SP Method) was employed to immunostain and to elucidate the localization and distribution of HIF-1a and cox-2.Then we revealed and assessed the differences of them.Results: The immunoreactivity was demonstrated in the cells as following: (1)HIF-1a expressing cells were scarcely found in the former two groups(health group and deep carious group).They were significantly lower than the other two (all P<0.001),The third group were higher than the fourth group(P<0.05).The HIF-1a positive cells were odontoblasts, pulpal fibrophils, vascularendothelial cells and macrophages(positive neutrophils were only found in some acute pulpitis cases) (2)COX-2 expressing cells were scarcely found in first group; The second group mainly demonstrated slight to staining intensity ,but higher than the first group (P<0.05).The third group were the highest (P<0.001,P<0.05,P<0.05).The fourth group were higher than the first group (P<0.001)and the second group (P<0.05),but lower than the third group (P<0.05).The COX-2 positive cells were odontoblasts, pulpal fibroblasts vascularendothelial cells and macrophages (positive neutrophils could be found in some cases of the second group and of the third group).(3)We found that COX-2 developed up with HIF-1 a in third group ,but against it infourth group.Conclusions: (1)COX-2 and HIF-1 a were regularly expressing in inflammatory dental pulp.(2)The distribution of HIF-1 a and COX-2 was unequal;. (3)These findings indicate that HIF-1a and COX-2 may be two important factors in pulpal lesions and there is a significantly hypoxia condiction in inflamed pulp .(4)The increase of HIF-1 a is a possible mechanism for hypoxia preconditioning .(5)Our results suggested that pulpal fibroblasts as well as macrophages might be involved in the pathogenesis of irreversible pulpitis.