Hypoxia and collagen crosslinking in the healthy and affected sites of periodontitis patients

Vascular Endothelial Growth Factor A serum levels and common gene polymorphisms in generalized periodontitis affected patients

OBJECTIVE

To evaluate and compare the associations of VEGFA serum levels and SNPs (rs1570360, rs699947, rs3025033, and rs2146323) with periodontitis in study participants grouped by gender.

METHODS

The study enrolled 261 patients with periodontitis and 441 healthy controls as a reference group. Patients underwent periodontal examination and radiographic analysis to confirm the periodontitis diagnosis. Blood samples were collected, and the DNA salting-out method was used for DNA extraction from peripheral venous blood. Genotyping of VEGFA (rs1570360, rs699947, rs3025033, and rs2146323) was performed using real-time polymerase chain reaction (RT-PCR) and serum level analysis was done for 80 individuals - 40 periodontitis-affected patients and 40 reference group subjects.

RESULTS

The analysis of VEGFA (rs1570360, rs699947, rs3025033, and rs2146323) showed that the rs3025033 GG genotype was less frequent in the periodontitis group than in the reference group (1.6% vs. 5.7%,p = 0.008). VEGFA serum levels were not statistically significantly different between periodontitis patients and reference group subjects (554.29 (522.38) ng/ml vs. 581.32 (348.16) ng/ml, p = 0.786). Individuals carrying rs1570360, rs699947, rs3025033, and rs2146323 haplotype A-A-G-A had decreased risks of periodontitis, while rare haplotype of VEGFA (rs1570360, rs699947, rs3025033, and rs2146323) was associated with increased odds of periodontitis (OR= 0.42; 95% CI: 0.20-0.85; p < 0.017; OR= 4.08; 95% CI: 1.86-8.94; p < 0.0001, respectively).

CONCLUSION

The rs3025033 GG genotype and the rs1570360, rs699947, rs3025033, and rs2146323 A-A-G-A haplotypes may play a protective role in the development of periodontitis, but a less common haplotype of the same VEGFA polymorphism may be associated with the risk of developing periodontitis.

Berberine regulates bone metabolism in apical periodontitis by remodelling the extracellular matrix

OBJECTIVES

The objectives of this study were to explore the role and related mechanism of berberine in repairing bone destruction in apical periodontics (AP).

MATERIALS AND METHODS

AP was established in 14 of 21 male Wistar rats (four weeks of age; 70-80 g) for 3 weeks. The canals were cleaned and administered berberine (2 mg/ml; n = 7) or calcium hydroxide (100 mg/ml; control; n = 7), followed by glass ionomer cement sealing. After 3 weeks, specimen collection followed by micro-computed tomography (μ-CT) and histological staining was performed, including haematoxylin and eosin staining, Masson's trichrome staining, tartrate-resistant acid phosphatase staining, immunohistochemistry and immunofluorescence histochemistry.

RESULTS

μ-CT showed that AP lesion volume reduced in the berberine group. Histopathology showed that berberine decreased the activity and number of osteoclasts but increased the expression of proteins related to osteoblast differentiation, including alkaline phosphatase and osterix. The immune cell, T cell, dendritic cell and macrophage counts were significantly decreased in the berberine group. In the berberine group, the expression of extracellular matrix-degraded proteases, metalloproteinases, was decreased; however, that of extracellular matrix-stable proteases, lysyl oxidases, was increased.

CONCLUSIONS

Berberine controlled the inflammatory response and regulated bone metabolism in AP by reducing metalloproteinase expression and increasing lysyl oxidases expression.

VEGF as a potential molecular target in periodontitis: a meta-analysis and microarray data validation

BACKGROUND

Anti-vascular endothelial growth factor (VEGF) has been used as a therapeutic drug for the treatment of some human diseases. However, no systematic evidence is performed for assessing the role of VEGF in periodontitis. We carried out a comprehensive analysis to explore the role of VEGF in patients with periodontitis.

METHODS

Multiple databases were searched for eligible studies. The pooled standardized mean difference (SMD) and odds ratio (OR) with the corresponding 95% confidence interval (CI) were applied to evaluate the effect sizes. Clinical data validation from microarray analysis was used. Pathway and process enrichment analysis were also investigated.

RESULTS

Finally, 16 studies were included in this analysis. Overall, there was a significantly higher level of VEGF expression in periodontitis than in healthy control groups (OR = 16.64, 95% CI = 6.01-46.06, P < 0.001; SMD = 2.25, 95% CI = 1.25-3.24, P < 0.001). Subgroup analysis of ethnicity showed that VEGF expression was still correlated with periodontitis in the Asian and European populations. No correlation was observed between VEGF expression and age, gender, and pathological type. A large clinical sample data (427 periodontitis patients and 136 healthy controls) further validated that VEGF expression was higher in periodontitis than in healthy control groups (P = 0.023). VEGF was involved in many functions such as blood vessel development, response to growth factor, cell proliferation, and cell adhesion.

CONCLUSIONS

High levels of VEGF were credible implications for the development of periodontitis. Anti-VEGF therapy may be valuable for the treatment of periodontitis in clinical management.

Antioxidant Ascorbic Acid Modulates NLRP3 Inflammasome in LPS-G Treated Oral Stem Cells through NFκB/Caspase-1/IL-1β Pathway

Human gingival mesenchymal stem cells (hGMSCs) and endothelial committed hGMSCs (e-hGMSCs) have considerable potential to serve as an in vitro model to replicate the inflammation sustained by Porphyromonas gingivalis in periodontal and cardiovascular diseases. The present study aimed to investigate the effect of ascorbic acid (AA) on the inflammatory reverting action of lipopolysaccharide (LPS-G) on the cell metabolic activity, inflammation pathway and reactive oxygen species (ROS) generation in hGMSCs and e-hGMSCs. Cells were treated with LPS-G (5 μg mL⁻¹) or AA (50 μg mL⁻¹) and analyzed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay, immunofluorescence and Western blot methods. The rate of cell metabolic activity was decreased significantly in LPS-G-treated groups, while groups co-treated with LPS-G and AA showed a logarithmic cell metabolic activity rate similar to untreated cells. AA treatment attenuated the inflammatory effect of LPS-G by reducing the expression of TLR4/MyD88/NFκB/NLRP3/Caspase-1/IL-1β, as demonstrated by Western blot analysis and immunofluorescence acquisition. LPS-G-induced cells displayed an increase in ROS production, while AA co-treated cells showed a protective effect. In summary, our work suggests that AA attenuated LPS-G-mediated inflammation and ROS generation in hGMSCs and e-hGMSCs via suppressing the NFκB/Caspase-1/IL-1β pathway. These findings indicate that AA may be considered as a potential factor involved in the modulation of the inflammatory pathway triggered by LPS-G in an vitro cellular model.

Hypoxia and Porphyromonas gingivalis-lipopolysaccharide synergistically induce NLRP3 inflammasome activation in human gingival fibroblasts

OBJECTIVE

To investigate the effects of hypoxia and Porphyromonas gingivalis- lipopolysaccharide (P. gingivalis-LPS) on activation of the NACHT leucine-rich repeat protein 3 (NLRP3) inflammasome in human gingival fibroblasts (HGFs).

DESIGN

Periodontitis was optimally simulated using a hypoxic concentration of 1%. HGFs were stimulated using P. gingivalis-LPS (1.0 μg/ml) in normoxia and hypoxia for 3 h and 6 h, respectively. The expression levels of genes and proteins of hypoxia-inducible factor-1α (HIF-1α), interleukin-1β, gasdermin D (GSDMD) and the NLRP3 inflammasome, including NLRP3, apoptosis-associated speck-like protein containing CARD (ASC), caspase-1 and its activated forms, were measured using quantitative real-time polymerase chain reaction and western blot. ELISA was used to detect and determine levels of the inflammatory factor interleukin-1β in cell supernatants. Lactate dehydrogenase (LDH) release assay, caspase-1 activity assay and Hoechst 33342/Propidium Iodide (PI) staining were performed to further verify the presence of pyroptosis.

RESULTS

The NLRP3 inflammasome (i.e., NLRP3, ASC, caspase-1) was not affected by individual stimulation using P. gingivalis-LPS or hypoxia. However, the combination of both hypoxia and P. gingivalis-LPS stimulation significantly enhanced inflammasome activation and promoted the expression of interleukin-1β, gasdermin D and HIF-1α at gene and protein levels; PI positive cells and the release of LDH were also elevated.

CONCLUSION

Hypoxia and P. gingivalis-LPS synergistically induced NLRP3 inflammasome activation in HGFs, and subsequently high levels of interleukin-1β and GSDMD-mediated pyroptosis can cause an HGF inflammatory response, which plays an important role in the pathogenesis of periodontitis.

Long non-coding RNA 01126 promotes periodontitis pathogenesis of human periodontal ligament cells via miR-518a-5p/HIF-1α/MAPK pathway

BACKGROUND

Periodontitis is a prevalent oral inflammatory disease, which can cause periodontal ligament to a local hypoxia environment. However, the mechanism of hypoxia associated long non-coding RNAs (lncRNAs) involved in periodontitis is still largely unknown.

METHODS

Microarray was performed to detect the expression patterns of lncRNAs in 3 pairs of gingival tissues from patients with periodontitis and healthy controls. The expression of lncRNA 01126 (LINC01126), miR-518a-5p and hypoxia-inducible factor-1α (HIF-1α) in periodontal tissues and in human periodontal ligament cells (hPDLCs) under hypoxia was measured by quantitative real-time polymerase chain reaction or western blot. Fluorescence in situ hybridization and cell fraction assay were performed to determine the subcellular localization of LINC01126 and miR-518a-5p. Overexpression or knockdown of LINC01126 or HIF-1α was used to confirm their biological roles in hPDLCs. MTT assays were performed to evaluate hPDLCs proliferation ability. Flow cytometry was used to detect apoptosis. ELISA was used to measure the expression levels of interleukin (IL)-1β, IL-6, IL-8 and TNF-α. Dual-luciferase reporter assays were performed to assess the binding of miR-518a-5p to LINC01126 and HIF-1α. RNA immunoprecipitation assay was used to identify whether LINC01126 and miR-518a-5p were significantly enriched in AGO-containing micro-ribonucleoprotein complexes.

RESULTS

We selected LINC01126, which was the most highly expressed lncRNA, to further verify its functions in periodontitis-induced hypoxia. The expression of LINC01126 was increased in periodontal tissues. In vitro experiment demonstrated that LINC01126 suppressed proliferation, promoted apoptosis and inflammation of hPDLCs under hypoxia via sponging miR-518a-5p. Moreover, we identified HIF-1α acted as a direct target of miR-518a-5p in hPDLCs and LINC01126 promoted periodontitis pathogenesis by regulating the miR-518a-5p/HIF-1α/MAPK pathway.

CONCLUSION

LINC01126 promotes periodontitis pathogenesis of hPDLCs via miR-518a-5p/HIF-1α/MAPK pathway, providing a possible clue for LINC01126-based periodontal therapeutic approaches.