Periodontal inflammation triggers a site-specific and wide radius of calcium metabolic effects on alveolar bone

Genetic analysis of impaired healing responses after periodontal therapy in type 2 diabetes: Clinical and in vivo studies

OBJECTIVE

This study aims to investigate the mechanisms underlying the impaired healing response by diabetes after periodontal therapy.

BACKGROUND

Outcomes of periodontal therapy in patients with diabetes are impaired compared with those in patients without diabetes. However, the mechanisms underlying impaired healing response to periodontal therapy have not been sufficiently investigated.

MATERIALS AND METHODS

Zucker diabetic fatty (ZDF) and lean (ZL) rats underwent experimental periodontitis by ligating the mandibular molars for one week. The gingiva at the ligated sites was harvested one day after ligature removal, and gene expression was comprehensively analyzed using RNA-Seq. In patients with and without type 2 diabetes (T2D), the corresponding gene expression was quantified in the gingiva of the shallow sulcus and residual periodontal pocket after non-surgical periodontal therapy.

RESULTS

Ligation-induced bone resorption and its recovery after ligature removal were significantly impaired in the ZDF group than in the ZL group. The RNA-Seq analysis revealed 252 differentially expressed genes. Pathway analysis demonstrated the enrichment of downregulated genes involved in the peroxisome proliferator-activated receptor (PPAR) signaling pathway. PPARα and PPARγ were decreased in mRNA level and immunohistochemistry in the ZDF group than in the ZL group. In clinical, probing depth reduction was significantly less in the T2D group than control. Significantly downregulated expression of PPARα and PPARγ were detected in the residual periodontal pocket of the T2D group compared with those of the control group, but not in the shallow sulcus between the groups.

CONCLUSIONS

Downregulated PPAR subtypes expression may involve the impaired healing of periodontal tissues by diabetes.

Detection of orthodontically induced inflammatory root resorption-associated biomarkers from the gingival crevicular fluid by proteomics analysis: a randomized-controlled clinical trial

Orthodontically induced inflammatory root resorption (OIIRR) is an undesirable complication of orthodontic treatment (OT) with an ambiguous aetiologic mechanism. This study aimed to identify OIIRR-associated biomarkers in the gingival crevicular fluid (GCF) using proteomic analysis. In this randomized clinical trial, the upper first premolars (UFP) were exposed either to light or heavy force. The GCF was collected at 1 h, 1 day, 7 days, 14 days, 21 days, and 28 days following force application. After extraction of UFP, roots were imaged and resorption premolar, was used to deliver either light forcecraters were measured. Proteomic analysis of GCF was performed using 2D gel electrophoresis with MALDI-TOF/TOF MS/MS. Results were further analyzed by bioinformatics analyses showing the biological functions and predicted pathways. The predicted canonical pathways showed that the expression of immunoglobulin kappa (IGKC), neutrophil gelatinase-associated lipocalin (NGAL), neurolysin mitochondrial (NEUL), keratin, type II cytoskeletal 1 (K2C1), S100-A9, and the extracellular calcium-sensing receptor (CASR) were significantly associated with a range of biological and inflammatory processes. In conclusion, up-regulation of S100A9, CASR, and K2C1 suggested a response to force-related inflammation, chemotactic activities, osteoclastogenesis, and epithelial cell breakdown. Meanwhile, the up-regulation of IGKC, NGAL, and K2C1 indicated a response to the inflammatory process, innate immunity activation, and epithelial cell breakdown.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03572-5.

Relevant mechanisms of MAIT cells involved in the pathogenesis of periodontitis

Mucosal-associated invariant T (MAIT) cells are a group of unconventional T cells that are abundant in the human body, recognize microbial-derived vitamin B metabolites presented by MHC class I-related protein 1 (MR1), and rapidly produce proinflammatory cytokines, which are widely involved in the immune response to various infectious diseases. In the oral mucosa, MAIT cells tend to accumulate near the mucosal basal lamina and are more inclined to secrete IL-17 when activated. Periodontitis is a group of diseases that manifests mainly as inflammation of the gums and resorption of the alveolar bone due to periodontal tissue invasion by plaque bacteria on the dental surface. The course of periodontitis is often accompanied by a T-cell-mediated immune response. This paper discussed the pathogenesis of periodontitis and the potential contribution of MAIT cells to periodontitis.

Deuterohemin-Ala-His-Thr-Val-Glu-Lys (DhHP-6) Mimicking Enzyme as Synergistic Antioxidant and Anti-Inflammatory Material for Periodontitis Therapy

Periodontitis is an inflammatory disease induced by plaque microorganisms. In the clinic, antibiotic assistant periodontal mechanical therapy is the most effective therapy for the treatment of periodontitis. However, the drug resistance of the antibiotics and the repeated coming and diminishing of the disorder of oxidation-reduction balance in the inflammatory tissue could not meet the high requirements for periodontic health control in long periods. Deuterohemin-ala-his-thr-val-glu-lys (DhHP-6) is a biomimetic oxidase-mimicking enzyme that simulates the reactive oxygen radical scavenger function of heme by synthesizing the new molecular material following the key structure and amino acid sequence of heme. In this article, we report the antioxidant and anti-inflammatory properties of DhHP-6 by building a inflammatory model for human gingival fibroblasts (HGFs) stimulated by lipolysaccharide (LPS) and its effects on periodontitis in Wistar rats. DhHP-6 reduced the oxidative stress of HGFs by increasing the amount of the reductase species of glutathione (GSH) and catalase (CAT) while decreasing the amount of oxidase species of malonaldehyde (MDA) and reactive oxygen species (ROS). DhHP-6 had a dose-dependent protective effect on alveolar bone absorption in rats with periodontitis, enhanced antioxidant capacity, and reduced inflammation. As determined by Micro-CT scanning, DhHP-6 reduced alveolar bone loss and improved the bone structure of the left maxillary first molar of rats. There were no obvious morphological and histological differences in the rat organs with or without DhHP-6 treatment. These results suggest that DhHP-6 can be used to treat periodontitis by increasing the expression levels of antioxidant enzymes and antioxidants in systemic and local tissues, thereby reducing levels of oxidation products and cyto-inflammatory factors. The synergistic antioxidant and anti-inflammatory effects of DhHP-6 suggest that there are promising applications of this biomimetic enzyme molecular material for the next generation of agents for periodontitis therapy.

Wound healing in periodontal disease induces macrophage polarization characterized by different arginine-metabolizing enzymes

BACKGROUND AND OBJECTIVE

Macrophages play important roles from the initiation of inflammation to wound healing. Two phenotypes of macrophages, namely pro-inflammatory type macrophages (M1-MΦ) and anti-inflammatory type macrophages (M2-MΦ), have been reported. Two contrasting metabolic enzymes that use arginine as a substrate, inducible nitric oxide synthase (iNOS), and arginase-1 (Arg-1), have been identified as M1-MΦ and M2-MΦ markers, respectively. The purpose of this study was to elucidate the temporal dynamics of the macrophage phenotype during the progression and healing phases of experimental periodontitis in mice.

MATERIAL AND METHODS

A total of 63 C57BL/6J mice were divided into the following 3 groups: control (C), periodontitis (P), and healing (H). To induce periodontitis, a silk ligature was placed around the maxillary bilateral second molars of mice in the periodontitis and healing groups. In the healing group, the ligature was removed 3 days after ligation to induce tissue healing. Maxillary tissue was collected on day 0 for the control group, days 1, 3, 5, and 7 for the periodontitis group (P1, P3, P5, and P7), and days 5 and 7 for the healing group (H5 and H7: 3 days with the ligation + 2 days or 4 days following ligature removal). The left side of the maxilla was subjected to bone structure analysis using micro-computed tomography and gene expression analysis using polymerase chain reaction. On the right side, immunohistochemistry was performed to histopathologically evaluate the localization of macrophages by phenotype in the periodontal tissue.

RESULTS

In the alveolar bone structure analysis, the linear distance of bone height increased significantly in the P5 and P7 groups, whereas bone volume fraction and bone mineral density decreased over time after ligature placement; in the healing group (H5 and H7), these parameters improved significantly compared with the periodontitis group (P5 and P7). Expression of genes encoding pro-inflammatory cytokines and iNOS increased in the periodontitis group, and expression of anti-inflammatory cytokine genes and Arg-1 increased in the healing group. Furthermore, the iNOS/Arg-1 expression ratio increased with ligation, whereas the ratio in the healing groups (H5 and H7) significantly decreased compared with the periodontitis groups (P5 and P7). Immunofluorescence staining revealed a significant increase in the number of iNOS-positive macrophages in the periodontitis group and decrease in the healing group. In contrast, the number of Arg-1-positive macrophages decreased in the periodontitis group and increased in the healing group.

CONCLUSION

The results of the present study suggest that wound healing in periodontal disease induces macrophage polarization from M1-MΦ to M2-MΦ characterized by iNOS and Arg-1.