Microtomographic, histomorphometric, and molecular features show a normal alveolar bone healing process in iNOS-deficient mice along a compensatory upregulation of eNOS and nNOS isoforms

Author(s)

Francisconi, Carolina Favaro ; Colavite, Priscila Maria ; Fonseca, Angelica Cristina ; Azevedo, Michelle de Campos Soriani ; Tabanez, Andre Petenuci ; Melchiades, Jessica Lima ; Vieira, Andreia Espindola ; Repeke, Carlos Eduardo Palanch ; Claudino, Marcela ; Garlet, Gustavo Pompermaier

• Document type: Journal article
• Source: Journal of Applied Oral Science; v. 31, p. 12-pg., 2023-01-01.

Abstract

Inducible nitric oxide synthase (iNOS) is one of the enzymes responsible for the synthesis of nitric oxide (NO), which is an important signaling molecule with effects on blood vessels, leukocytes, and bone cells. However, the role of iNOS in alveolar bone healing remains unclear. This study investigated the role of iNOS in alveolar bone healing after tooth extraction in mice. Methodology: C57Bl/6 wild type (WT) and iNOS genetically deficient (iNOS-KO) mice were subjected to upper incision tooth extraction, and alveolar bone healing was evaluated by micro-computed tomography (mu CT) and histological/histomorphometric, birefringence, and molecular methods. Results: The expression of iNOS had very low control conditions, whereas a significant increase is observed in healing sites of WT mice, where iNOS mRNA levels peak at 7d time point, followed by a relative decrease at 14d and 21d. Regarding bone healing, both WT and iNOS-KO groups showed the usual phases characterized by the presence of clots, granulation tissue development along the inflammatory cell infiltration, angiogenesis, proliferation of fibroblasts and extracellular matrix synthesis, bone neoformation, and remodeling. The overall micro-computed tomography and histomorphometric and birefringence analyses showed similar bone healing readouts when WT and iNOS-KO strains are compared. Likewise, Real-Time PCR array analysis shows an overall similar gene expression pattern (including bone formation, bone resorption, and inflammatory and immunological markers) in healing sites of WT and iNOS-KO mice. Moreover, molecular analysis shows that nNOS and eNOS were significantly upregulated in the iNOS-KO group, suggesting that other NOS isoforms could compensate the absence of iNOS. Conclusion: The absence of iNOS does not result in a significant modulation of bone healing readouts in iNOS-KO mice. The upregulation of nNOS and eNOS may compensate iNOS absence, explaining the similar bone healing outcome in WT and iNOS-KO strains. (AU)

• FAPESP's process: 10/13626-7 - Morphometric and molecular characterization of iNOS role in alveolar bone repair under homeostatic and infectious conditions
• Grantee: Carolina Fávaro Francisconi Mortari
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 18/08741-3 - ROLE OF MSCs IN THE RESPONSE TO THE IMPLANTATION OF TITANIUM DEVICES AND ITS IMPACT ON THE REPAIR AND OSSEOINTEGRATION PROCESS
• Grantee: Carolina Fávaro Francisconi Mortari
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 15/24637-3 - MSCs and m2 as determinants of the constructive or destructive nature of inflammatory microenvironments associated with bone tissue
• Grantee: Gustavo Pompermaier Garlet
• Support Opportunities: Research Projects - Thematic Grants