Electroacupuncture regulates macrophage, neutrophil, and oral microbiota to alleviate alveolar bone loss and inflammation in experimental ligature-induced periodontitis

FoxO1-modulated macrophage polarization regulates osteogenesis via PPAR-γ signaling

Periodontitis, a common chronic inflammatory disease, epitomizes a significant impairment in the host immune system and an imbalance of bone metabolism. Macrophage polarization, a dynamic process dictated by the microenvironment, intricately contributes to the interplay between the immune system and bone remodeling, namely the osteoimmune system. Forkhead box protein O1 (FoxO1) has been shown to play a dramatic role in mediating oxidative stress, bone mass, as well as cellular metabolism. Nevertheless, the function and underlying mechanisms of FoxO1 in regulating macrophage polarization-mediated osteogenesis in periodontitis remain to be further elucidated. Here, we found that FoxO1 expression was closely linked to periodontitis, accompanied by aggravated inflammation. Notably, FoxO1 knockdown skewed macrophage polarization from M1 to the antiinflammatory M2 phenotype under inflammatory conditions, which rescued the impaired osteogenic potential. Mechanistically, we revealed that the enhancement of the transcription of peroxisome proliferator-activated receptor (PPAR) signaling in FoxO1-knockdown macrophages. In agreement with this contention, GW9662, a specific inhibitor of PPAR-γ signaling, greatly aggravated macrophage polarization from M2 to the M1 phenotype and attenuated osteogenic potential under inflammatory conditions. Additionally, PPAR-γ signaling agonist rosiglitazone (RSG) was applied to address ligature-induced periodontitis with attenuated inflammation. Our data lend conceptual credence to the function of FoxO1 in mediating macrophage polarization-regulated osteogenesis which serves as a novel therapeutic target for periodontitis.

Integrating network pharmacology and experimental evaluation to explore the complementary therapeutic effect and mechanism of melatonin in periodontitis

Objective

To explore the potential targets for melatonin in the treatment of periodontitis through network pharmacologic analysis and experimental validation via in vivo animal models and in vitro cellular experiments.

Materials and methods

In this study, we first screened melatonin targets from Pharm Mapper for putative targets, Drug Bank, and TCMSP databases for known targets. Then, disease database was searched and screened for differential expressed genes associated with periodontitis. The intersection of disease and melatonin-related genes yielded potential target genes of melatonin treatment for periodontitis. These target genes were further investigated by protein-protein interaction network and GO/KEGG enrichment analysis. In addition, the interactions between melatonin and key target genes were interrogated by molecular docking simulations. Then, we performed animal studies to validate the therapeutic effect of melatonin by injecting melatonin into the peritoneal cavity of ligation-induced periodontitis (LIP) mice. The effects of melatonin on the predicted target proteins were also analyzed using Western blot and immunofluorescence techniques. Finally, we constructed an in vitro cellular model and validated the direct effect of melatonin on the predicted targets by using qPCR.

Results

We identified 8 potential target genes by network pharmacology analysis. Enrichment analysis suggests that melatonin may treat periodontitis by inhibiting the expression of three potential targets (MPO, MMP8, and MMP9). Molecular docking results showed that melatonin could effectively bind to MMP8 and MMP9. Subsequently, melatonin was further validated in a mouse LIP model to inhibit the expression of MPO, MMP8, and MMP9 in the periodontal tissue. Finally, we verified the direct effect of melatonin on the mRNA expression of MPO, MMP8, and MMP9 in an in vitro cellular model.

Conclusions

Through a combination of network pharmacology and experimental validation, this study provides a more comprehensive understanding of the mechanism of melatonin to treat periodontitis. Our study suggests that MPO, MMP8, and MMP9 as key target genes of melatonin to treat periodontitis. These findings present a more comprehensive basis for further investigation into the mechanisms of pharmacological treatment of periodontitis by melatonin.

Computational analysis of curcumin-mediated alleviation of inflammation in periodontitis patients with experimental validation in mice

AIM

Using network pharmacology and experimental validation to explore the therapeutic efficacy and mechanism of curcumin (Cur) in periodontitis treatment.

MATERIALS AND METHODS

Network pharmacology was utilized to predict target gene interactions of Cur-Periodontitis. Molecular docking was used to investigate the binding affinity of Cur for the predicted targets. A mouse model with ligature-induced periodontitis (LIP) was used to verify the therapeutic effect of Cur. Microcomputed tomography (micro-CT) was used to evaluate alveolar bone resorption, while western blotting, haematoxylin-eosin staining and immunohistochemistry were used to analyse the change in immunopathology. SYTOX Green staining was used to assess the in vitro effect of Cur in a mouse bone marrow-isolated neutrophil model exposed to lipopolysaccharide.

RESULTS

Network pharmacology identified 114 potential target genes. Enrichment analysis showed that Cur can modulate the production of neutrophil extracellular traps (NETs). Molecular docking experiments suggested that Cur effectively binds to neutrophil elastase (ELANE), peptidylarginine deiminase 4 (PAD4) and cathepsin G, three enzymes involved in NETs. In LIP mice, Cur alleviated alveolar bone resorption and reduced the expression of ELANE and PAD4 in a time-dependent but dose-independent manner. Cur can directly inhibit NET formation in the cell model.

CONCLUSIONS

Our research suggested that Cur may alleviate experimental periodontitis by inhibiting NET formation.

Amuc_1100 pretreatment alleviates acute pancreatitis in a mouse model through regulating gut microbiota and inhibiting inflammatory infiltration

Amuc_1100 is a membrane protein from Akkermansia muciniphila, which has been found to play a role in host immunological homeostasis in the gastrointestinal tract by activating TLR2 and TLR4. In this study we investigated the effects and underlying mechanisms of Amuc_1100 on acute pancreatitis (AP) induced in mice by intraperitoneal injection of caerulein and lipopolysaccharide (LPS). The mice were treated with the protein Amuc_1100 (3 μg, i.g.) for 20 days before caerulein injection. Cecal contents of the mice were collected for 16S rRNA sequencing. We found that pretreatment with Amuc_1100 significantly alleviated AP-associated pancreatic injury, reduced serum amylase and lipase. Amuc_1100 pretreatment significantly inhibited the expression of proinflammatory cytokines (TNF-α, IL-1β, IFN-γ and IL-6) in spleen and pancreas through inhibiting NF-κB signaling pathway. Moreover, Amuc_1100 pretreatment significantly decreased the inflammatory infiltration, accompanied by the reduction of Ly6C+ macrophages and neutrophils in the spleen of AP mice. Gut microbiome analysis showed that the abundance of Bacteroidetes, Proteobacteria, Desulfobacterota and Campilobacterota was decreased, while the proportion of Firmicutes and Actinobacteriota was increased in AP mice pretreated with Amuc_1100. We further demonstrated that Amuc_1100 pretreatment restored the enrichment of tryptophan metabolism, which was mediated by intestinal flora. These results provide new evidence that Amuc_1100 lessens the severity of AP through its anti-inflammatory properties with a reduction of macrophages and neutrophil infiltration, as well as its regulation of the composition of intestinal flora and tryptophan metabolism.

Integrated microbiome and metabolomics revealed the protective effect of baicalin on alveolar bone inflammatory resorption in aging

BACKGROUND

With the growing aging population and longer life expectancy, periodontitis and tooth loss have become major health concerns. The gut microbiota, as a key regulator in bone homeostasis, has gathered immense interest. Baicalin, a flavonoid compound extracted from Scutellaria baicalensis Georgi, has shown antioxidant and anti-inflammatory activities.

PURPOSE

This study investigated, for the first time, the protective mechanism of baicalin against alveolar bone inflammatory resorption in aging mice by regulating intestinal flora and metabolites, as well as intestinal barrier function.

METHODS

A ligature-induced periodontitis model was established in d-galactose (D-gal)-induced aging mice, and baicalin was administered at different dosages for 13 weeks. Body weight was measured weekly. The antioxidant and anti-inflammatory activity of baicalin were evaluated using serum superoxide dismutase (SOD), malonaldehyde (MDA), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) levels. The immune capability was assessed by thymus and spleen indices. Histopathological changes were observed in the heart, liver, ileum, and periodontal tissues. Alveolar bone absorption of maxillary second molars was examined, and osteoclasts were counted by tartrate-resistant acid phosphatase (TRAP) staining. Furthermore, fecal samples were analyzed using 16S rRNA sequencing and non-targeted metabolomics to identify differences in intestinal bacterial composition and metabolites.

RESULTS

Baicalin exhibited anti-aging properties, as evidenced by increased SOD activity and decreased levels of MDA, IL-6, and TNF-α in serum compared to the control group. Baicalin also ameliorated alveolar bone loss in the d-gal-induced aging-periodontitis group (p < 0.05). Furthermore, baicalin restored ileal permeability by up-regulating the expression of ZO-1 and occludin in aging-periodontitis groups (p < 0.05). Alpha diversity analysis indicated that baicalin-treated mice harbored a higher diversity of gut microbe. PCoA and ANOSIM results revealed significant dissimilarity between groups. The Firmicutes/Bacteroidetes (F/B) ratio, which decreased in periodontitis mice, was restored by baicalin treatment. Additionally, medium-dosage baicalin promoted the production of beneficial flavonoids, and enriched short-chain fatty acids (SCFAs)-producing bacteria.

CONCLUSION

Intestinal homeostasis is a potential avenue for treating age-related alveolar bone loss. Baicalin exerts anti-inflammatory, antioxidant, and osteo-protective properties by regulating the gut microbiota and metabolites.

Porphyromonas gingivalis induces an inflammatory response via the cGAS-STING signaling pathway in a periodontitis mouse model

Periodontitis is an inflammatory disease initiated by periodontopathogenic bacteria in the dental plaque biofilms. Understanding the role of Porphyromonas gingivalis (P. gingivalis), a keystone pathogen associated with chronic periodontitis, in the inflammatory response is crucial. Herein, we investigated whether P. gingivalis infection triggers the expression of the type I IFN gene and various cytokines and leads to activation of the cGAMP synthase-stimulator of IFN genes (cGAS-STING) pathway both in vitro and in a mouse model. Additionally, in an experimental model of periodontitis using P. gingivalis, Sting^Gt mice showed lower levels of inflammatory cytokines and bone resorption than wild-type mice. Furthermore, we report that a STING inhibitor (SN-011) significantly decreased inflammatory cytokine production and osteoclast formation in a periodontitis mouse model with P. gingivalis. In addition, STING agonist (SR-717) -treated periodontitis mice displayed enhanced macrophage infiltration and M1 macrophage polarization in periodontal lesions compared with that in vehicle-treated periodontitis mice. In conclusion, our results demonstrate that the cGAS-STING signaling pathway may be one of the key mechanisms crucial for the P. gingivalis-induced inflammatory response that leads to chronic periodontitis.