Basic Fibroblast Growth Factor (bFGF) in Periodontal Ligament Tissue

Abstract

Chronic gingivitis and periodontitis are the most common forms of periodontal disease. They are endemic in most populations and are a major factor contributing to poor oral health and loss of teeth. The health of gingivae, periodontal ligament (PDL) and alveolar bone, is constantly at risk to pathological changes induced by oral bacteria (dental plaque); the severity of the response and progress of disease is dependent on several factors, particularly the immune system of the host tissues. Once the PDL has been destroyed, it is usually difficult to achieve its regrowth and reattachment to the tooth root. Recent increased understanding of polypeptide growth factors has indicated their potential role in the growth, repair and regeneration of PDL tissue. Deficiency or inhibition of growth factor action may explain the clinical failure to obtain regeneration and reattachment of PDL tissue following appropriate treatment and elimination of the causative factors of periodontitis. The objectives of this study were to determine whether basic fibroblast growth factor (bFGF) is expressed in PDL tissue and, if so, to measure the amounts of bFGF in normal and disease conditions. PDL tissue and cells were obtained from extracted human teeth. Tissue was isolated by trypsinization followed by centrifuging the extracts for 3 min at 2500 rpm. The distribution of bFGF in healthy and abnormal PDL tissue was examined by immunohistochemistry and ELISA. Immunostaining for bFGF was localized in fibroblasts, endothelial cells, fibrocytes and the extracellular matrix (ECM). Staining was observed to be stronger in nuclei than in cytoplasm. bFGF staining was also stronger in the PDL of healthy control teeth than in the PDL of teeth with periodontal lesions. Tissues from older patients (ages 73 and 74) with chronic periodontitis showed weaker staining for bFGF than tissues from younger patients (ages 31-48). In a diseased (chronic gingivitis) tissue immunostaining for bFGF was stronger in endothelial cells than in fibroblasts. Fibroblast numbers were significantly (P≤0.0005) higher in healthy PDL than in the PDL of teeth with periodontal lesions. There were also significant (P≤0.0005) differences in fibrocyte numbers between the tissues of PDL from healthy control teeth and PDL from chronic periodontitis. Fibroblast numbers were significantly (P≤0.0005) greater than fibrocyte numbers in healthy PDL, but were significantly (P≤0.0005) lower than fibrocyte numbers in all of the disease groups. Cells cultured from PDL tissue of teeth with chronic periodontitis showed a swollen cytoplasm, weak basophilic and irregular nuclear fission. The immunostaining for bFGF was also stronger in the cultured cells from healthy PDL than in the cells from tissue with chronic periodontitis. bFGF was measured in PDL tissue using a double antibody sandwich ELISA. bFGF levels (3-866 ng/mg protein) were greater in healthy controls than in the disease groups (P≤0.025), but there were no significant (P>0.1) differences in the PDL of diseased tissues. It is concluded that the bFGF in PDL tissue was produced mainly by fibroblasts and endothelial cells and that the numbers of fibroblasts and their bFGF content were substantially decreased in all forms of periodontal lesions. The influence of age on bFGF content in PDL tissue is unclear. A role for bFGF in diminished tissue regeneration during periodontal diseases remains unproven.