Tnf-alpha-tnfr1 signaling differentially regulates periapical bone loss and neoformation dentin in a murine experimental model

Author(s)

Luciano Aparecido de Almeida Júnior

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Odontologia de Ribeirão Preto (PCARP/BC)
• Defense date: 2023-01-30

Examining board members

Francisco Wanderley Garcia de Paula e Silva; Daniele Lucca Longo; Vivien Thiemy Sakai; Raquel Assed Bezerra Segato

• Advisor: Francisco Wanderley Garcia de Paula e Silva

Abstract

Tumor necrosis factor-alpha is a pro-inflammatory cytokine related to bone destruction of some inflammatory diseases. When it binds to its TNFR1 and TNFR2 receptors, it has distinct functions of cell inflammation and apoptosis or inflammation control and hemostasis, respectively. Thus, the general objective of this study was to investigate the role of TNF-&alpha; in inflammation, in the development of periapical lesion and in pulpal repair using mice genetically deficient in mediator receptor-1 (TNFRSF1- Knockout) as an experimental model compared to wild animals. (C57BL6 - Wild-Type). For the study of the periapical lesion, one hundred mice, 50 Knockout animals and 50 Wild-type animals were used. After anesthesia, the pulp tissue was exposed to the oral environment for microbial contamination for 7, 14, 28 and 42 days. For pulp repair, forty mice were used, 20 knockout animals and 20 wild-type animals. After anesthesia, pulp exposure was performed and later direct pulp protection with MTA was performed and followed up for 7 and 70 days. After the euthanasia of the animals, the blocks containing tooth and bone were used for microtomographic, histopathological, histomorphometric, histomicrobiological evaluation, number of osteoclasts, RT-PCR and immunohistochemistry. The periapical lesion was characterized by wide spacing of the periodontal ligament and recruitment of inflammatory cells. The absence of TNFR1 contained periapical lesion formation within 42 days (p<0.05). The number of neutrophils was lower at 14, 28 and 42 days in Knockout animals (p<0.05). TNFR1 ablation resulted in lower osteoclast formation at 14 and 42 days (p<0.05), lower Rankl expression (p<0.0001) and Opg expression was reduced at 28 days (p<0.0001). The RANKL/OPG ratio was favorable to reabsorption at 7 and 42 days in Wild-Type (p<0.0001). In the absence of TNFR1, the expression of mRNA for Tnf-&alpha; was lower at 7 and 28 days (p<0.0001), accordingly, the expression of Mmp9, CtsK and Ptsg2 was lower at 7 (p<0.0001). The neoformation of mineralized tissue was limited in knockout animals at 70 days (p<0.0001). Knockout animals developed pulpal necrosis and periapical lesion at 70 days (p<0.0001), in addition to greater recruitment of neutrophils (p=0.0003). The lack of TNFR1 led to lower marking for TNF-&alpha; at 7 and 70 days (p<0.05), consequently, lower synthesis of mineralization markers DSP (p=0.0003) and OPN (p=0.0289). The absence of TNF-&alpha;/TNFR1 binding contained the development of the periapical lesion and decreased the expression of genes related to bone catabolism from the early stages of the periapical lesion. In the pulp repair, the lack of TNFR1 limited the formation of mineralized tissue, it was shown with a greater inflammatory process of the pulp tissue that generated pulp necrosis and development of the periapical lesion. (AU)

• FAPESP's process: 19/02432-1 - Role of tumor necrosis factor-alpha in pulpal and periapical inflammation and repair
• Grantee: Luciano Aparecido de Almeida Junior
• Support Opportunities: Scholarships in Brazil - Doctorate