Expression and immunohistochemical localization of leptin receptor in human periapical granuloma.

AIM: To investigate the expression and immunohistochemical localization of leptin receptor (LEPR) in human periapical granulomas. METHODOLOGY: Periapical inflammatory lesions were obtained from extracted human teeth and teeth which underwent periapical surgery. After their histopathological categorization as periapical granulomas (n = 20), they were examined by immunohistochemistry using human LEPR monoclonal antibodies. LEPR mRNA expression was also determined by quantitative real-time PCR (qRT-PCR), and the amount of LEPR protein was analysed by immunoblot. RESULTS: All granuloma samples expressed LEPR. Amongst inflammatory cells, only macrophages showed expression of LEPR. Western blot analysis revealed the presence in the samples of a protein with apparent molecular weight of ~120 kDa, corresponding to the estimated molecular weight of LEPR. The qRT-PCR analysis demonstrated the expression of LEPR mRNA, corresponding the size of the amplified fragment (338 bp), assessed by agarose gel electrophoresis, to that of LEPR mRNA. CONCLUSIONS: Human periapical granulomas express LEPR. In periapical granulomas, only macrophages showed expression of LEPR. This finding suggests that leptin can play a role in inflammatory and immune periapical responses.

Leptin expression in healthy and inflamed human dental pulp.

AIM: To investigate the expression of leptin in healthy and inflamed human dental pulp. METHODOLOGY: Twenty-one pulp samples were obtained from freshly caries- and restoration-free extracted human third molars. In seven-third molars (inflamed pulp group), inflammation was induced prior to extraction. Pulp samples were processed, and leptin expression was determined by quantitative real-time PCR (qRT-PCR) and the amount of leptin by immunoblot. RESULTS: All healthy and inflamed dental pulp samples expressed leptin. Western blot analysis revealed the presence of a protein with an apparent molecular weight of ~16 kDa in human dental pulp, which corresponds to the estimated molecular weight of leptin. The expression of leptin mRNA in dental pulp was confirmed by qRT-PCR analysis, and the size of the amplified fragments (296 bp for leptin and 194 bp for cyclophilin) was confirmed by agarose gel electrophoresis. The expression of leptin in the inflamed pulp group was significantly greater (P < 0.05) than in healthy teeth. The relative amount of leptin in inflamed pulps was almost twice than in healthy pulps. CONCLUSIONS: For the first time, the presence of leptin in human dental pulp tissues has been demonstrated. The upregulation of leptin expression in inflamed pulp samples suggests that leptin can play a role in pulpal inflammatory and immune responses.