Electroacupuncture increases immunoexpression of CB1 and CB2 receptors in experimental model of inflammatory bone loss

KDM4D enhances osteo/dentinogenic differentiation and migration of SCAPs via binding to RPS5

OBJECTIVES

Stem cells of the apical papilla (SCAPs) provide promising candidates for dental pulp regeneration. Despite great advances in the transcriptional controls of the SCAPs fate, little is known about the regulation of SCAP differentiation.

MATERIALS AND METHODS

Short hairpin RNAs and full-length RNA were used to deplete or overexpress lysine demethylase 4D (KDM4D) gene expression. Western blotting, real-time RT-PCR, alizarin red staining, and scratch migration assays were used to study the role of KDM4D and the ribosomal protein encoded by RPS5 in SCAPs. RNA microarray, chromatin Immunoprecipitation (ChIP), and co-immunoprecipitation (Co-IP) assays were performed to explore the underlying molecular mechanisms.

RESULTS

KDM4D enhanced the osteo/dentinogenic differentiation, migration, and chemotaxis of SCAPs. The microarray results revealed that 88 mRNAs were differentially expressed in KDM4D-overexpressed SCAPs. ChIP results showed knock-down of KDM4D increased the level of H3K9me2 and H3K9me3 in CNR1 promoter region. There were 37 possible binding partners of KDM4D. KDM4D was found to combine with RPS5, which also promoted the osteo/dentinogenic differentiation, migration, and chemotaxis of SCAPs.

CONCLUSIONS

KDM4D promoted the osteo/dentinogenic differentiation and migration potential of SCAPs in combination with RPS5, which provides a therapeutic clue for improving SCAPs-based dental tissue regeneration.

Involvement of the endocannabinoid system in current and recurrent periodontitis: A human study

OBJECTIVE

The aim of the present study was to assess if the endocannabinoid system is involved differently in patients with recurrent and non-recurrent periodontal disease and if in sites that have a predisposition for reactivation, levels of anandamide (AEA) change after periodontal therapy.

BACKGROUND

Periodontal disease (PD) may be due to a dysregulation of the endocannabinoid system.

METHODS

Periodontal patients were recruited, treated for PD and monitored. Gingival samples from these patients with recurrent (n = 10) and non-recurrent (n = 10) periodontal disease were harvested before and after treatment and compared to those of periodontally healthy (n = 10) subjects. Levels of CB1 and CB2, AEA and CBs receptor activation were assessed in healthy and inflamed samples using immunohistochemistry, chromatography and autoradiography. In healed sites, AEA levels were also assessed.

RESULTS

The number of CBs in inflamed sites of recurrent patients was significantly higher than in those with non-recurrent disease and also higher than those in healthy subjects. Inflamed sites of recurrent patients had significantly lower CBs receptor activation than those of healthy subjects. Levels of AEA in inflamed sites of non-recurrent patients were significantly higher than those found both in inflamed recurrent sites and in healthy sites. Otherwise, the amount of AEA in healthy subjects and recurrent inflamed sites was similar. After periodontal therapy, levels of AEA were significantly lower in both periodontal groups. In recurrent sites, they resulted significantly lower than in non-recurrent and even in healthy subjects.

CONCLUSIONS

The endocannabinoid system seems involved differently in subjects with recurrent and non-recurrent periodontal disease.

Electroacupuncture repairs intestinal barrier by upregulating CB1 through gut microbiota in DSS-induced acute colitis

BACKGROUND

A few studies have reported that electroacupuncture (EA) can repair the intestinal barrier through unknown mechanisms. Cannabinoid receptor 1 (CB1) was shown to play an important role in the protection of the gut barrier in recent studies. Gut microbiota can influence the expression of CB1. In this study, we explored the effect of EA on the gut barrier in acute colitis and its mechanism.

METHODS

A dextran sulfate sodium (DSS)-induced acute colitis model, CB1 antagonist model and fecal microbiota transplantation (FMT) model were used in this study. The disease activity index (DAI) score, colon length, histological score, and inflammatory factors were detected to evaluate colonic inflammation. Methods for detecting intestinal barrier functions included the expression of tight junction proteins, intestinal permeability, and the number of goblet cells. Moreover, 16S rRNA sequencing was applied to analyze alterations in the gut microbiota. Western blotting and RT-PCR were performed to assess the levels of CB1 and autophagy-related proteins. Autophagosomes were observed by transmission electron microscopy.

RESULTS

EA reduced the DAI score, histological score, levels of inflammatory factors, and restored the colon length. Moreover, EA increased the expression of tight junction proteins and the number of goblet cells, and decreased intestinal permeability. In addition, EA remodeled the community structure of the gut microbiota, increased the expression of CB1, and enhanced the degree of autophagy. However, the therapeutic effects were reversed by CB1 antagonists. In addition, FMT in the EA group exhibited similar effects to EA and upregulated CB1.

CONCLUSIONS

We concluded that EA may protect intestinal barrier functions by increasing the expression of CB1 to enhance autophagy through gut microbiota in DSS-induced acute colitis.

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

AIM

Electroacupuncture (EA) regulates distant body physiology through somatic sensory autonomic reflexes, balances the microbiome, and can promote the release of immune cells into bloodstream, thereby inhibiting severe systemic inflammation. This makes it possible to use EA as an integrated treatment for periodontitis.

MATERIALS AND METHODS

In this study, EA was applied to the ST36 acupoints in a ligature-induced periodontitis (LIP) mouse model. Then the effects of EA on periodontal myeloid cells, cytokines, and the microbiome were comprehensively analysed using flow cytometry, quantitative Polymerase Chain Reaction (PCR), and 16 S sequencing.

RESULTS

Results demonstrated that EA could significantly relieve periodontal bone resorption. EA also suppressed the infiltration of macrophages and neutrophils, reduced gene expression of the pro-inflammatory cytokines IL-1β, IL-6, IL-17 and TNF-α, and increased expression of the anti-inflammatory factors IL-4 and IL-10 in periodontal tissues. Moreover, composition of the periodontal microbiome was regulated by EA, finding that complex of microbiota, including supragingival Veillonella, subgingival Streptococcus, and subgingival Erysipelatoclostridium, were significantly reduced. Meanwhile, nitrate and nitrate-related activities of subgingival microbiota were reversed. Network analysis revealed close relationships among Veillonella, Streptococcus, and Bacteroides.

CONCLUSIONS

Our study indicates that EA can effectively alleviate inflammation and bone resorption in LIP mice, potentially via the regulation of myeloid cells, cytokines, and periodontal microbiome.

Potential Mechanisms Underlying Marijuana-Associated Periodontal Tissue Destruction

While definitive evidence awaits, cannabis is emerging as a likely risk factor for periodontal tissue destruction. The mechanisms that underlie potential cannabis-induced or cannabis-enhanced periodontal diseases, however, remain to be elucidated. Herein, we 1) examine insights obtained from the endocannabinoid system, 2) summarize animal models of exposure to cannabinoid receptor agonists and antagonists, 3) review the evidence suggesting that cannabis and cannabis-derived molecules exert a profound influence on components of the oral microbiome, and 4) assess studies indicating that marijuana and phytocannabinoids compromise the immune response to plaque. Furthermore, we address how knowledge of cannabinoid influences in the oral cavity may be exploited to provide potential novel periodontal therapeutics, while recognizing that such medicinal approaches may be most appropriate for nonhabitual marijuana users. The suspected increase in susceptibility to periodontitis in marijuana users is multifaceted, and it is clear that we are only beginning to understand the complex toxicological, cellular, and microbial interactions involved. With marijuana consumption increasing across all societal demographics, periodontal complications of use may represent a significant, growing oral health concern. In preparation, an enhanced research response would seem appropriate.

Electroacupuncture Reduces Inflammation but Not Bone Loss on Periodontitis in Arthritic Rats

Periodontitis and rheumatoid arthritis (RA) are inflammatory diseases characterized by chronic inflammation and bone erosion. Electroacupuncture (EA) shows anti-inflammatory and anti-resorptive effects in experimental periodontitis (EP) and in RA. It is important to investigate whether EA shows these effects in periodontal tissues in the presence of these two inflammatory diseases or not. For this, Wistar rats were divided into six groups: control (C); experimental rheumatoid arthritis (RA; bovine type II collagen-induced (CII)); experimental periodontitis (EP); RA/EP (RA + EP); EP/EA (EP treated with EA); RA/EP/EA (RA + EP treated with EA). EP was induced 21 days after RA induction and EA was performed previously and during the EP induction period, every 3 days until the 36th experimental day. The rats were euthanized on day 39. RA was evaluated by edema and the withdrawal threshold of hind paws. The maxillae were removed, and alveolar bone loss (ABL) and bone radiographic density (BRD) were evaluated. Immunohistochemical analyses for interleukins (IL)-6 and -17 and nuclear factor (NF)-κB were performed. Our results showed that EA reduced only the pain intensity in arthritic rats. Histomorphometric, macroscopic, and radiographic analyses did not show differences between the control and EP/EA groups. EA caused a reduction in ABL and BRD only in the presence of EP. EA caused a reduction in IL-6 and -17 in all groups, but NF-κB was only reduced in the arthritic rats with EP. In conclusion, EA reduced the inflammation related to periodontitis in arthritic rats but did not prevent ABL.

Bones and Joints: The Effects of Cannabinoids on the Skeleton

CONTEXT

The endocannabinoid system uses tissue-specific lipid ligands and G protein‒coupled transmembrane receptors to regulate neurologic, metabolic, and immune responses. Recent studies demonstrate that the endocannabinoid system influences bone metabolism. With the increasing use of endocannabinoid mimetics (e.g., tetrahydrocannabinol and cannabidiol), the involvement of endocannabinoids in bone growth and remodeling has become clinically relevant.

EVIDENCE ACQUISITION

This literature review is based on a search of PubMed and Google Scholar databases as of June 2019 for all English-language publications relating to cannabinoids and bone. We evaluated retrieved articles for relevance, experimental design, data acquisition, statistical analysis, and conclusions.

EVIDENCE SYNTHESIS

Preclinical studies establish a role for endocannabinoids in bone metabolism. These studies yield complex and often contradictory results attributed to differences in the specific experimental model examined. Studies using human cells or subjects are limited.

CONCLUSIONS

In vitro and animal models document that endocannabinoids are involved in bone biology. The relevance of these observations to humans is not clear. The increasing long-term use of medical and recreational cannabis underscores the need to better understand the role of endocannabinoids in human bone metabolism. Moreover, it is important to evaluate the role of endocannabinoids as a therapeutic target to prevent and treat disorders associated with bone loss.