Correlation between Transforming Growth Factor-β and Periapical Lesions in Patients with Chronic Apical Periodontitis

OBJECTIVE: To examine the expression of transforming growth factor-β (TGF-β) in the periapical granulation tissue and serum of patients with chronic apical periodontitis and to conduct immunohistochemical analysis so as to explore the relationship between TGF-β and the degree of periapical lesions. METHODS: Periapical granulation tissues of 20 cases of chronic apical periodontitis were collected as the experimental group. Healthy gingival tissues without eruption of third molars of 5 cases were collected as the control group. Immunohistochemistry, enzyme-linked immunosorbent assay, and real-time PCR (RT-PCR) were utilized to determine the expression of TGF-β mRNA and protein, and the difference in the expression of TGF-β was compared between groups. In the experimental group, oral CBCT was taken to measure the periapical bone resorption area. Spearman's correlation method was applied to analyze the correlation between TGF-β protein and gene expression levels and periapical bone resorption area. RESULTS: Immunohistochemistry and enzyme-linked immunosorbent assay demonstrated that the expression of TGF-β protein in chronic apical periodontitis tissue and serum was higher than that in the controls (P < 0.05). RT-PCR revealed that the expression of TGF-β mRNA was higher in chronic apical periodontitis tissue than that of the controls (P < 0.05). Spearman's correlation analysis showed that in the experimental group, the mRNA expression of TGF-β was positively correlated with the periapical bone resorption area (P < 0.01), and the protein expression level was not correlated with the periapical bone resorption area (P < 0.05). CONCLUSION: The increased expression of TGF-β in the periapical granulation tissue and serum of patients with chronic apical periodontitis has a certain correlation with the progression of periapical periodontitis. The correlation between TGF-β at the mRNA level and the degree of early stage disease as well as the high expression of TGF-β in inflammatory cells in immunohistochemistry have confirmed that TGF-β promotes bone resorption in early periapical periodontitis, and its mechanism of action deserves further investigation.