AT1 and AT2 Receptor Knockout Changed Osteonectin and Bone Density in Mice in Periodontal Inflammation Experimental Model

• Main Authors: Maria Laura de Souza Lima, Caroline Addison Carvalho Xavier de Medeiros, Gerlane Coelho Bernardo Guerra, Robson Santos, Michael Bader, Flavia Q. Pirih, Raimundo Fernandes de Araújo Júnior, Alan B. Chan, Luis J. Cruz, Gerly Anne de Castro Brito, Renata Ferreira de Carvalho Leitão, Ericka Janine Dantas da Silveira, Vinicius Barreto Garcia, Agnes Andrade Martins, Aurigena Antunes de Araújo
• Format: Article
• Language: English
• Published: MDPI AG 2021-05-01
• Series: International Journal of Molecular Sciences
• Subjects: bone; micro-computed tomography; periodontitis; inflammation; osteonectin
• Online Access: https://www.mdpi.com/1422-0067/22/10/5217

Background: The aim of this study was to evaluate the role of AT1 and AT2 receptors in a periodontal inflammation experimental model. Methods: Periodontal inflammation was induced by LPS/<i>Porphyromonas gingivalis</i>. Maxillae, femur, and vertebra were scanned using Micro-CT. Maxillae were analyzed histopathologically, immunohistochemically, and by RT-PCR. Results: The vertebra showed decreased BMD in AT1 H compared with WT H (<i>p</i> < 0.05). The femur showed increased Tb.Sp for AT1 H and AT2 H, <i>p</i> < 0.01 and <i>p</i> < 0.05, respectively. The Tb.N was decreased in the vertebra (WT H-AT1 H: <i>p</i> < 0.05; WT H-AT2 H: <i>p</i> < 0.05) and in the femur (WT H-AT1 H: <i>p</i> < 0.01; WT H-AT2 H: <i>p</i> < 0.05). AT1 PD increased linear bone loss (<i>p</i> < 0.05) and decreased osteoblast cells (<i>p</i> < 0.05). RANKL immunostaining was intense for AT1 PD and WT PD (<i>p</i> < 0.001). OPG was intense in the WT H, WT PD, and AT2 PD when compared to AT1 PD (<i>p</i> < 0.001). AT1 PD showed weak immunostaining for osteocalcin compared with WT H, WT PD, and AT2 PD (<i>p</i> < 0.001). AT1 H showed significantly stronger immunostaining for osteonectin in fibroblasts compared to AT2 H (<i>p</i> < 0.01). Conclusion: AT1 receptor knockout changed bone density, the quality and number of bone trabeculae, decreased the number of osteoblast cells, and increased osteonectin in fibroblasts.