osteoprotegerin and Dental-Pulp-Exposure

Apical periodontitis is an inflammation and destruction of periapical tissues. Matrix metalloproteinase-9 (MMP-9) is thought to be involved in periapical lesion formation and progression. The aim of this study was to evaluate the lesion progression in MMP-9 knockout (KO) mice compared with that in control mice (wild type [WT]).. The pulps of mouse mandibular first molars were exposed; animals were killed at 0, 7, 14, 21, and 28 days after surgery. Hematoxylin-eosin-stained sections were observed for the description of pulpal, apical, periapical features, and the periapical lesion size. The periapical lesion size was further measured with micro-computed tomographic imaging. The number of osteoclasts was also counted by tartrate-resistant acid phosphatase histoenzymology. Real-time polymerase chain reaction and immunohistochemistry were used to analyze the expression levels of receptor activator of NF-κB (RANK), receptor activator of NF-κB ligand (RANKL), osteoprotegerin (OPG), interleukin-1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), MMP-2, and MMP-8.. There was a significant difference (P < .05) between the 2 types of animals regarding the periapical lesion size, which was larger in MMP-9 KO animals. No significant differences (P > .05) were found between WT and MMP-9 KO mice related to the osteoclast number as well as the pulpal, apical, and periapical features. More neutrophil cells were observed in MMP-9 KO animals than WT mice (P < .05). The expression levels of RANK, RANKL, OPG, IL-1β, TNF-α, MMP-2, and MMP-8 were found up-regulated in MMP-9 KO mice (P < .05).. MMP-9 KO animals developed larger periapical lesions with greater inflammatory response, indicating an important role of MMP-9 in the host's immune and inflammatory response to root canal and periradicular infection.

Topics: Acid Phosphatase; Animals; Cell Count; Dental Pulp Exposure; Disease Progression; Interleukin-1beta; Isoenzymes; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 8; Matrix Metalloproteinase 9; Mice; Mice, Knockout; Neutrophils; Osteoclasts; Osteoprotegerin; Periapical Periodontitis; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Tartrate-Resistant Acid Phosphatase; Tumor Necrosis Factor-alpha; X-Ray Microtomography

The development of periapical granulomas is dependent on the host response and involves Th1, Th2, Th17, and Treg-related cytokines. The discovery of new Th9 and Th22 subsets, with important immunomodulatory roles mediated by interleukin (IL)-9 and IL-22, respectively, emphasizes the need for reevaluation of current cytokine paradigms in context of periapical lesions. We investigated the expression of IL-9 and IL-22 in active and stable human granulomas and throughout experimental lesion development in mice.. Periapical granulomas (N = 83) and control specimens (N = 24) were evaluated regarding the expression of IL-9 and IL-22 via real-time polymerase chain reaction. Experimental periapical lesions were induced in mice (pulp exposure and bacterial inoculation) and the lesions evolution correlation with IL-9 and IL-22 expression kinetics was evaluated.. IL-9 and IL-22 mRNA expression was higher in periapical lesions than in control samples; higher levels of IL-9 and IL-22 were observed in inactive than in active lesions. In the experimental lesions model, increasing levels of IL-9 and IL-22 mRNA were detected in the lesions, and inverse correlations were found between IL-9 and IL-22 and the increase of lesion area in the different time point intervals.. Our results suggest that Th9 and Th22 pathways may contribute to human and experimental periapical lesion stability.

Topics: Actinomycosis; Adolescent; Adult; Animals; Bacteroidaceae Infections; Dental Pulp Exposure; Disease Models, Animal; Female; Fusobacterium Infections; Fusobacterium nucleatum; Humans; Immunomodulation; Interleukin-22; Interleukin-9; Interleukins; Male; Mice; Middle Aged; Osteoprotegerin; Periapical Granuloma; Porphyromonas gingivalis; Prevotella nigrescens; RANK Ligand; T-Lymphocyte Subsets; T-Lymphocytes, Helper-Inducer; T-Lymphocytes, Regulatory; Young Adult

Long-term sequential expression of receptor activator of NF-κB ligand (RANKL) and osteoprotegrin (OPG) in lipopolysaccharide (LPS)-induced rat periapical lesions has not been studied..   Seventy-two 4-week-old Wistar rats were divided into eight experimental groups and one control group (eight animals in each).. Lipopolysaccharide-induced periapical lesions were produced in rats by occlusal exposure of the pulp of their lower first molars in all experimental groups but not the control group. The extent of periapical destruction was measured by radiographic imaging. RANKL and OPG mRNA were measured in all tissue sections containing the periapical lesions as well as the control group every week from week 1 to week 8 by real-time quantitative reverse transcription polymerase chain reaction. RANKL and OPG protein were determined by immunohistochemistry. Osteoclasts were identified by enzyme histochemistry.. The sequential changes in the mRNA and protein expression of RANKL and OPG were largely compatible with the occurrence of osteoclasts histologically and enzymes histochemically, as well as the mean areas of the periapical lesions radiographically during long-term observation of the LPS-induced rat periapical lesions.. This study may be the first to demonstrate the long-term RANKL and OPG expression every week from week 1 to week 8 using LPS to produce periapical infection in a Wistar rat model. The long-term findings of high expressions of RANKL and OPG further extend the potential application of the Wistar rat model for future experimental trials using RANKL inhibitor to evaluate the treatment outcome for LPS-induced rat periapical lesions.

Topics: Acid Phosphatase; Alveolar Bone Loss; Animals; Biomarkers; Cell Count; Dental Pulp Exposure; Disease Models, Animal; Escherichia coli; Giant Cells; Image Processing, Computer-Assisted; Immunohistochemistry; Isoenzymes; Lipopolysaccharides; Male; Osteoclasts; Osteoprotegerin; Periapical Diseases; Radiography, Bitewing; RANK Ligand; Rats; Rats, Wistar; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; Tartrate-Resistant Acid Phosphatase; Time Factors

Nitric oxide (NO) derived from inducible nitric oxide synthase (iNOS) plays an important role in host defense, as well as in inflammation-induced tissue lesions. Here we evaluated the role of NO in bone loss in bacterial infection-induced apical periodontitis by using iNOS-deficient mice (iNOS(-/-)). The iNOS(-/-) mice developed greater inflammatory cell recruitment and osteolytic lesions than WT mice. Moreover, tartrate-resistant acid-phosphatase-positive (TRAP(+)) osteoclasts were significantly more numerous in iNOS(-/-) mice. Furthermore, the increased bone resorption in iNOS(-/-) mice also correlated with the increased expression of receptor activator NF-kappaB (RANK), stromal-cell-derived factor-1 alpha (SDF-1 alpha/CXCL12), and reduced expression of osteoprotegerin (OPG). These results show that NO deficiency was associated with an imbalance of bone-resorption-modulating factors, leading to severe infection-stimulated bone loss.

Topics: Acid Phosphatase; Actinomycosis; Alveolar Bone Loss; Animals; Bacterial Infections; Bacteroidaceae Infections; Biomarkers; Cell Count; Cell Movement; Chemokine CXCL12; Dental Pulp Exposure; Isoenzymes; Mice; Mice, Inbred C57BL; Mice, Inbred Strains; Nitric Oxide; Nitric Oxide Synthase Type II; Osteoclasts; Osteolysis; Osteoprotegerin; Periapical Periodontitis; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Tartrate-Resistant Acid Phosphatase