In vivo and In vitro Identification of Endocannabinoid Signaling in Periodontal Tissues and Their Potential Role in Local Pathophysiology

Unleashing the therapeutic role of cannabidiol in dentistry

Cannabidiol (CBD) found in Cannabis sativa is a non-psychoactive compound which is capable of binding to CB1 and CB2 receptors. CBD has recently gained interest in dentistry although it has not been explored sufficiently yet. The therapeutic effects of CBD include anti-inflammatory, analgesic, antioxidant, biological and osteoinductive properties. The aim of this review is to highlight these effects with respect to various oral conditions and shed light on the current limitations and prospects for the use of CBD in maintaining oral health.

Effects of cannabinoid receptor activation on Porphyromonas gingivalis lipopolysaccharide stimulation in human periodontal ligament stem cells in vitro

PURPOSE

Periodontitis is an inflammatory disease that results in the loss of periodontal tissue. The endocannabinoid system has anti-inflammatory properties and displays considerable potential for tissue regeneration. In this study, we aimed to explore whether the activation of this system can alleviate or reverse the inflammatory phenotype of human periodontal ligament stem cells (hPDLSCs) induced by exposure to the inflammagen lipopolysaccharide (LPS).

METHODS

We investigated the effects of activating specific cannabinoid receptors (CB1 and CB2) on the inflammatory phenotype of LPS-stimulated hPDLSCs. The exogenous ligands WIN55,212-2 and JWH-133 were employed to target the cannabinoid receptors. We conducted a thorough assessment of cell proliferation, metabolic activity, and adipogenic, osteogenic, and chondrogenic differentiation potential. Additionally, we measured cytokine release using enzyme-linked immunosorbent assays.

RESULTS

Exposure to Porphyromonas gingivalis lipopolysaccharide (Pg-LPS) caused an increase in cell proliferation while decreasing metabolic activity. While this exposure did not influence adipogenic or chondrogenic differentiation, it did result in reduced osteogenesis. Additionally, LPS induced the release of interleukin (IL)-6, IL-8, and monocyte chemoattractant protein 1. Immunolabeling revealed the presence of CB1 and CB2 on the cellular membrane, with these receptors playing distinct roles in hPDLSCs. The CB1 agonist WIN55,212-2 was found to increase metabolic activity and promote adipogenic differentiation, whereas the CB2 agonist JWH-133 promoted cell proliferation and osteogenic differentiation. When hPDLSCs were co-exposed to Pg-LPS and CB ligands, JWH-133 slightly ameliorated the inhibition of osteogenic differentiation and suppressed the release of inflammatory cytokines.

CONCLUSIONS

This study clarifies the effects of specific CB receptor activation on hPDLCs and the inflammatory phenotype. Stimulation of the endocannabinoid system through the manipulation of endogenous or the application of exogenous cannabinoids in vivo may represent a potent therapeutic option for combating periodontal inflammatory disorders.

The Role of Different Types of Cannabinoids in Periodontal Disease: An Integrative Review

This integrative review addresses the potential of the Endocannabinoid System (ES) and cannabinoids in the pathogenesis and treatment of periodontal disease (PD). Cannabinoid receptors are expressed in healthy and inflamed periodontal tissues, indicating a potential regulatory role for SEC in oral homeostasis. Healthy periodontal cells express more CB1 receptors, while inflamed sites show increased CB2 receptors. This suggests a dynamic involvement of the SEC in the inflammatory response associated with PD. Cannabinoids such as cannabidiol (CBD) and cannabinoid receptor agonists such as HU-308, anandamide (AEA), and methanamide (Meta-AEA) have demonstrated promising therapeutic potential in studies. CBD has been associated with the control of bone resorption, antibacterial activity, and increased production of gingival fibroblasts, indicating effects in mitigating the progression of PD. HU-308 demonstrated preventive effects against alveolar bone loss, and anti-inflammatory, osteoprotective, and pro-homeostatic properties in animal models of periodontitis. AEA and Meta-AEA have anti-inflammatory effects by reducing pro-inflammatory mediators such as IL-1, IL-6, and TNF-α. The activation of cannabinoid receptors attenuates inflammatory processes, inhibits alveolar bone loss, exerts antibacterial effects, and promotes tissue repair. However, clinical trials are especially needed to validate these results and explore the therapeutic potential of cannabinoids in the treatment of PD in humans.

Cannabidiol and its application in the treatment of oral diseases: therapeutic potentials, routes of administration and prospects

Cannabidiol (CBD), one of the most important active ingredients in cannabis, has been reported to have some pharmacological effects such as antibacterial and analgesic effects, and to have therapeutic potential in the treatment of oral diseases such as oral cancer, gingivitis and periodontal diseases. However, there is a lack of relevant systematic research and reviews. Therefore, based on the etiology and clinical symptoms of several common oral diseases, this paper focuses on the therapeutic potential of CBD in periodontal diseases, pulp diseases, oral mucosal diseases, oral cancer and temporomandibular joint diseases. The pharmacological effects of CBD and the distribution and function of its receptors in the oral cavity are also summarized. In order to provide reference for future research and further clinical application of CBD, we also summarize several possible routes of administration and corresponding characteristics. Finally, the challenges faced while applying CBD clinically and possible solutions are discussed, and we also look to the future.

Phytocannabinoids and gingival inflammation: Preclinical findings and a placebo-controlled double-blind randomized clinical trial with cannabidiol

OBJECTIVE

The aim of this study was to: (1) evaluate the anti-inflammatory effects of cannabidiol (CBD) on primary cultures of human gingival fibroblasts (HGFs) and (2) to clinically monitor the effect of CBD in subjects with periodontitis.

BACKGROUND

The use of phytocannabinoids is a new approach in the treatment of widely prevalent periodontal disease.

MATERIALS AND METHODS

Cannabinoid receptors were analyzed by western blot and interleukin production detected using enzyme immunoassay. Activation of the Nrf2 pathway was studied via monitoring the mRNA level of heme oxygenase-1. Antimicrobial effects were determined by standard microdilution and 16S rRNA screening. In the clinical part, a placebo-control double-blind randomized study was conducted (56 days) in three groups (n = 90) using dental gel without CBD (group A) and with 1% (w/w) CBD (group B) and corresponding toothpaste (group A - no CBD, group B - with CBD) for home use to maintain oral health. Group C used dental gel containing 1% chlorhexidine digluconate (active comparator) and toothpaste without CBD.

RESULTS

Human gingival fibroblasts were confirmed to express the cannabinoid receptor CB2. Lipopolysaccharide-induced cells exhibited increased production of pro-inflammatory IL-6 and IL-8, with deceasing levels upon exposure to CBD. CBD also exhibited antimicrobial activities against Porphyromonas gingivalis, with an MIC of 1.5 μg/mL. Activation of the Nrf2 pathway was also demonstrated. In the clinical part, statistically significant improvement was found for the gingival, gingival bleeding, and modified gingival indices between placebo group A and CBD group B after 56 days.

CONCLUSIONS

Cannabidiol reduced inflammation and the growth of selected periodontal pathogenic bacteria. The clinical trial demonstrated a statistically significant improvement after CBD application. No adverse effects of CBD were reported by patients or observed upon clinical examination during the study. The results are a promising basis for a more comprehensive investigation of the application of non-psychotropic cannabinoids in dentistry.

The role of cannabinoid receptor 2 in bone remodeling during orthodontic tooth movement

BACKGROUND

The purpose of this study is to explore the effects of CB2 on bone regulation during orthodontic tooth movement.

METHODS

Thirty male mice were allocated into 2 groups (n = 15 in each group): wild type (WT) group and CB2 knockout (CB2-/-) group. Orthodontic tooth movement (OTM) was induced by applying a nickel-titanium coil spring between the maxillary first molar and the central incisors. There are three subgroups within the WT groups (0, 7 and 14 days) and the CB2-/- groups (0, 7 and 14 days). 0-day groups without force application. Tooth displacement, alveolar bone mass and alveolar bone volume were assessed by micro-CT on 0, 7 and 14 days, and the number of osteoclasts was quantified by tartrate-resistant acid phosphatase (TRAP) staining. Moreover, the expression levels of RANKL and OPG in the compression area were measured histomorphometrically.

RESULTS

The WT group exhibited the typical pattern of OTM, characterized by narrowed periodontal space and bone resorption on the compression area. In contrast, the accelerated tooth displacement, increased osteoclast number (P < 0.0001) and bone resorption on the compression area in CB2-/- group. Additionally, the expression of RANKL was significantly upregulated, while OPG showed low levels in the compression area of the CB2 - / - group (P < 0.0001).

CONCLUSIONS

CB2 modulated OTM and bone remodeling through regulating osteoclast activity and RANKL/OPG balance.

Cannabinoids in Periodontology: Where Are We Now?

INTRODUCTION

Cannabinoids are a well-documented treatment modality for various immune and inflammatory diseases, including asthma, chronic obstructive pulmonary disease, Crohn's disease, arthritis, multiple sclerosis, and a range of neurodegenerative conditions. However, limited information is available regarding the therapeutic potential of cannabinoids in treating periodontal disease.

OBJECTIVE

The objective of this study is to analyze the current evidence on the antibacterial and immunomodulatory effects of cannabis and its role in the healing and regeneration processes within periodontal tissues.

RESULTS

This review discusses the potential role of cannabinoids in restoring periodontal tissue homeostasis.

CONCLUSIONS

The examination of the endocannabinoid system and the physiological effects of cannabinoids in the periodontium suggests that they possess immunomodulatory and antibacterial properties, which could potentially promote proper tissue healing and regeneration.

Cannabidiol for Oral Health: A New Promising Therapeutical Tool in Dentistry

The medical use of cannabis has a very long history. Although many substances called cannabinoids are present in cannabis, Δ9tetrahydrocannabinol (Δ9-THC), cannabidiol (CBD) and cannabinol (CBN) are the three main cannabinoids that are most present and described. CBD itself is not responsible for the psychotropic effects of cannabis, since it does not produce the typical behavioral effects associated with the consumption of this drug. CBD has recently gained growing attention in modern society and seems to be increasingly explored in dentistry. Several subjective findings suggest some therapeutic effects of CBD that are strongly supported by research evidence. However, there is a plethora of data regarding CBD's mechanism of action and therapeutic potential, which are in many cases contradictory. We will first provide an overview of the scientific evidence on the molecular mechanism of CBD's action. Furthermore, we will map the recent developments regarding the possible oral benefits of CBD. In summary, we will highlight CBD's promising biological features for its application in dentistry, despite exiting patents that suggest the current compositions for oral care as the main interest of the industry.

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.

Cannabis Bioactive Compound-Based Formulations: New Perspectives for the Management of Orofacial Pain

The management of orofacial pain to alleviate the quality of life of affected patients is becoming increasingly challenging for scientific research and healthcare professionals. From this perspective, in addition to conventional therapies, new alternatives are being sought, increasingly looking at the use of both natural and synthetic products. Cannabis sativa L. represents an interesting source of bioactive compounds, including non-psychoactive cannabinoids, flavonoids, and terpenes, many of which are effective in improving pain intensity. Here, we aim to analyze the possible mechanisms of action of the bioactive natural and synthetic hemp-derived compounds responsible for the modulatory effects on pain-related pathways. The ability of these compounds to act on multiple mechanisms through a synergistic effect, reducing both the release of inflammatory mediators and regulating the response of the endocannabinoid system, makes them interesting agents for alternative formulations to be used in orofacial pain.

Immune challenges upregulate the expression of cannabinoid receptors in cultured human odontoblasts and gingival fibroblasts

Odontoblasts and gingival fibroblasts play essential roles in the physiological and pathological processes of dental tissue. Cannabinoid receptors (CB1 and CB2) are involved in analgesia by modulating the función of calcium channels that inhibit the synthesis of some neurotransmitters. A better understanding of the physiology of these receptors would provide the possibility of using them as therapeutic targets in controlling dental pain. The aim of this study was to evaluate the presence and activity of cannabinoid receptors in human odontoblast-like cells (OLC) and human gingival fibroblasts (HGF). CB1 and CB2 transcription was analyzed by real-time PCR, proteins were detected by immunofluorescence, and functional cannabinoid receptors were evaluated by measuring intracellular calcium concentration after stimulation with cannabidiol (CBD) and pre-treatment with a CB1 antagonist, a CB2 inverse agonist and a TRPV1 antagonist. Transcripts for CB1 and CB2 were found in both odontoblasts and gingival fibroblasts. Cannabidiol induced an increase in [Ca2+]i in both cells types, but surprisingly, pre-treatment with selective cannabinoid antagonists attenuated this effect, suggesting a functional communication between specific cannabinoid receptors and other CBD target receptors. In conclusion, human odontoblasts and gingival fibroblasts express functional CB1 and CB2 cannabinoid receptors, which could be modulated to improve the treatment of pain or dental sensitivity.

Cannabidiol and periodontal inflammatory disease: A critical assessment

Cannabidiol (CBD), a non-psychotropic cannabinoid produced by the genus Cannabis, is a phytoceutical that activates the endocannabinoid system (ECS) through binding to CB1 and CB2 receptors. The ECS is involved in cellular homeostasis and regulates metabolic processes in virtually all mammalian tissues. Published studies on CBD focus, inter alia, on its use in prophylaxis and as an anti-inflammatory agent. Here the authors present a critical assessment of the effects of CBD on inflammatory periodontal diseases caused by bacterial virulence factors, and evaluate critically the possible benefits and drawbacks of CBD use in dentistry. Particular attention is paid to the interaction of CBD with microbially colonized oral tissues, the inflammatory response in relation to the immune response, and the destruction/regeneration of hard and soft tissues of the periodontium.

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.

The cannabinoid receptor I (CB1) enhanced the osteogenic differentiation of BMSCs by rescue impaired mitochondrial metabolism function under inflammatory condition

Background

Periodontitis is a chronic infectious disease leading to bone resorption and periodontal tissue disruption under inflammatory stimulation. The osteogenic differentiation ability of mesenchymal stem cells (MSCs) is impaired under the inflammatory environment, which limits the effect of treatment. The cannabinoid receptor I (CB1) is the main effector of the endogenous cannabinoid system (ECS), and our previous study verified that CB1 could enhance the osteo/dentinogenic differentiation of dental MSCs, which might be a target for alveolar bone regeneration. However, the effect of CB1 on the osteogenic differentiation of MSCs derived from bone remains unknown. In present study, we investigated the role and mechanism of CB1 on mitochondrial function and osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs) under inflammatory environment.

Methods

Alkaline phosphatase (ALP) activity, alizarin red staining, quantitative calcium analysis, and osteogenic markers were used to detect the osteogenic differentiation ability of BMSCs. Real-time RT-PCR and Western blot were used to detect the gene expression. Seahorse Cell Mito Stress Test was used to detect the oxygen consumption rate (OCR). JC-10 assay was used to determine the mitochondrial membrane potential (MMP).

Results

CB1 increased osteogenic differentiation potential and mitochondrial energy metabolism, including the OCR, MMP, and enhanced the expressions of Nrf1 and Nrf2 in hBMSCs without or with TNF-α or INF-γ stimulation. Then, the inhibitor of mitochondrial electron transport chain (ETC), rotenone (ROT), inhibited the osteogenic differentiation in hBMSCs, and CB1 could rescue ROT impaired osteogenic differentiation potentials of hBMSCs without or with TNF-α or INF-γ stimulation. Activation of ETC by Coenzyme Q10 (CoQ10) could restore the impaired osteogenic differentiation of hBMSCs by depletion of CB1 without or with TNF-α or INF-γ stimulation. Mechanismly, CB1 could activate the JNK signaling pathway, p38 MAPK signaling pathway, and inhibit the Erk1/2 signaling pathway.

Conclusions

The activating of CB1 enhanced the osteogenic differentiation by rescuing the mitochondrial metabolism function in hBMSCs under the inflammatory environment, suggesting that CB1 is a potential target for enhancing bone regeneration under the inflammatory environment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02702-9.

Cannabinoids Drugs and Oral Health-From Recreational Side-Effects to Medicinal Purposes: A Systematic Review

Background: marijuana, the common name for cannabis sativa preparations, is one of the most consumed drug all over the world, both at therapeutical and recreational levels. With the legalization of medical uses of cannabis in many countries, and even its recreational use in most of these, the prevalence of marijuana use has markedly risen over the last decade. At the same time, there is also a higher prevalence in the health concerns related to cannabis use and abuse. Thus, it is mandatory for oral healthcare operators to know and deal with the consequences and effects of cannabis use on oral cavity health. This review will briefly summarize the components of cannabis and the endocannabinoid system, as well as the cellular and molecular mechanisms of biological cannabis action in human cells and biologic activities on tissues. We will also look into oropharyngeal tissue expression of cannabinoid receptors, together with a putative association of cannabis to several oral diseases. Therefore, this review will elaborate the basic biology and physiology of cannabinoids in human oral tissues with the aim of providing a better comprehension of the effects of its use and abuse on oral health, in order to include cannabinoid usage into dental patient health records as well as good medicinal practice. Methods: the paper selection was performed by PubMed/Medline and EMBASE electronic databases, and reported according to the PRISMA guidelines. The scientific products were included for qualitative analysis. Results: the paper search screened a total of 276 papers. After the initial screening and the eligibility assessment, a total of 32 articles were considered for the qualitative analysis. Conclusions: today, cannabis consumption has been correlated to a higher risk of gingival and periodontal disease, oral infection and cancer of the oral cavity, while the physico-chemical activity has not been completely clarified. Further investigations are necessary to evaluate a therapeutic efficacy of this class of drugs for the promising treatment of several different diseases of the salivary glands and oral diseases.

Expression of cannabinoid and cannabinoid-related receptors in the oral mucosa of healthy cats and cats with chronic gingivostomatitis

OBJECTIVES

Feline chronic gingivostomatitis (FCGS) is an oral disease. Cats with FCGS experience intense oral pain. Some cats remain refractory to current therapies based on dental extraction and adjuvant medical treatment; it is therefore necessary to investigate alternative therapeutic targets involved in inflammatory mechanisms and pain, namely the endocannabinoid system (ECS). The present study investigated the expression of cannabinoid receptors type 1 (CB1R) and 2 (CB2R), and cannabinoid-related receptors G protein-coupled receptor 55 (GPR55), transient receptor potential ankyrin 1 (TRPA1) and serotonin 1a receptor (5-HT1aR), in the oral mucosa of healthy cats to determine whether there was altered expression and distribution in cats with FCGS.

METHODS

Samples of caudal oral mucosa were collected from eight control cats (CTRL cats) and from eight cats with FCGS (FCGS cats). Tissue samples were processed using an immunofluorescence assay with cat-specific antibodies, and the immunolabelling of the receptors studied was semiquantitatively evaluated.

RESULTS

The mucosal epithelium of the CTRL cats showed CB1R, TRPA1 and 5-HT1aR immunoreactivity (IR), while CB2R and GPR55 IR were generally not expressed. In the CTRL cats, the subepithelial inflammatory cells expressed CB2R, GPR55 and 5-HT1aR IR. In the FCGS cats, all the receptors studied were markedly upregulated in the epithelium and inflammatory infiltrate.

CONCLUSIONS AND RELEVANCE

Cannabinoid and cannabinoid-related receptors are widely expressed in the oral mucosa of healthy cats and are upregulated during the course of FCGS. The presence of cannabinoid and cannabinoid-related receptors in healthy tissues suggests the possible role of the ECS in the homeostasis of the feline oral mucosa, while their overexpression in the inflamed tissues of FCGS cats suggests the involvement of the ECS in the pathogenesis of this disease, with a possible role in the related inflammation and pain. Based on the present findings, ECS could be considered a potential therapeutic target for patients with FCGS.

Cannabis and orofacial pain: a systematic review

The naturally occurring cannabis plant has played an established role in pain management throughout recorded history. However, in recent years, both natural and synthetic cannabis-based products for medicinal use (CBPM) have gained increasing worldwide attention due to growing evidence supporting their use in alleviating chronic inflammatory and neuropathic pain associated with an array of conditions. In view of these products' growing popularity in both the medical and commercial fields, we carried out a systematic review to ascertain the effects of cannabis and its synthetically derived products on orofacial pain and inflammation. The application of topical dermal cannabidiol formulation has shown positive findings such as reducing pain and improving muscle function in patients suffering from myofascial pain. Conversely, two orally-administered synthetic cannabinoid receptor agonists (AZD1940 and GW842166) failed to demonstrate significant analgesic effects following surgical third molar removal. There is a paucity of literature pertaining to the effects of cannabis-based products in the orofacial region; however, there is a wealth of high-quality evidence supporting their use for treating chronic nociceptive and neuropathic pain conditions in other areas. Further research is warranted to explore and substantiate the therapeutic role of CBPMs in the context of orofacial pain and inflammation. As evidence supporting their use expands, healthcare professionals should pay close attention to outcomes and changes to legislation that may impact and potentially benefit their patients.

Analogous modulation of inflammatory responses by the endocannabinoid system in periodontal ligament cells and microglia

Background

Periodontal ligament (PDL) cells initiate local immune responses, similar to microglia regulating primary host defense mechanisms in neuroinflammatory events of the central nervous system. As these two cell types manifest similarities in their immunomodulatory behavior, this study investigated the thesis that the immunological features of PDL cells might be modulated by the endocannabinoid system, as seen for microglia.

Methods

A human PDL cell line and an Embryonic stem cell-derived microglia (ESdM) cell line were grown in n = 6 experimental groups each, incubated with cannabinoid receptor agonists arachidonoylethanolamine (AEA) (50 μM) or Palmitoylethanolamide (PEA) (50 μM) and challenged with centrifugation-induced inflammation (CII) for 6 and 10 h. Untreated samples served as controls. Quantitative real-time polymerase chain reaction was applied for gene expression analyses of inflammatory cytokines, cannabinoid receptors and ionized calcium binding adaptor molecule 1 (IBA-1). Microglia marker gene IBA-1 was additionally verified on protein level in PDL cells via immunocytochemistry. Proliferation was determined with a colorimetric assay (WST-1 based). Statistical significance was set at p < 0.05.

Results

IBA-1 was inherently expressed in PDL cells both at the transcriptional and protein level. AEA counteracted pathological changes in cell morphology of PDL cells and microglia caused by CII, and PEA contrarily enhanced them. On transcriptional level, AEA significantly downregulated inflammation in CII specimens more than 100-fold, while PEA accessorily upregulated them. CII reduced cell proliferation in a time-dependent manner, synergistically reinforced by PEA decreasing cell numbers to 0.05-fold in PDL cells and 0.025-fold in microglia compared to controls.

Conclusion

PDL cells and microglia exhibit similar features in CII with host-protective effects for AEA through dampening inflammation and preserving cellular integrity. In both cell types, PEA exacerbated proinflammatory effects. Thus, the endocannabinoid system might be a promising target in the regulation of periodontal host response.

Methanandamide diminish the Porphyromonas gingivalis lipopolysaccharide induced response in human periodontal ligament cells

BACKGROUND

The endocannabinoid system is involved in the regulation of periodontal tissue homeostasis. Synthetic cannabinoid methanandamide (Meth-AEA) has improved stability and affinity to cannabinoid receptors compared to its endogenous analog anandamide. In the present study, we investigated the effect of methanandamide on the production of pro-inflammatory mediators in primary human periodontal ligament cells (hPdLCs).

METHODS

hPdLCs were treated with Meth-AEA for 24 h, and the resulting production of interleukin (IL)-6, IL-8, and monocyte chemotactic protein (MCP)-1 was measured in the absence or the presence of Porphyromonas gingivalis lipopolysaccharide (LPS). Additionally, the effect of Meth-AEA on the proliferation/viability of hPdLCs was measured by the MTT method.

RESULTS

Methanandamide at a concentration of 10 μM significantly inhibited P. gingivalis LPS induced production of IL-6, IL-8, and MCP-1. Basal production of IL-6 and IL-8 was slightly enhanced by 10 μM Meth-AEA. No effect of Meth-AEA on the basal production of MCP-1 was observed. Meth-AEA in concentrations up to 10 μM did not affect the proliferation/viability of hPdLCs, but significantly inhibited it at a concentration of 30 μM.

CONCLUSION

Our study suggests that the inflammatory response in periodontal ligament cells could be influenced by the activation of the cannabinoid system, which might be potentially involved in the progression of periodontal disease.

A novel serum-free medium for the isolation, expansion and maintenance of stemness and tissue-specific markers of primary human periodontal ligament cells

PURPOSE

Periodontal ligament (PDL) cell cultures are classically maintained in serum-containing media. However, unwanted side-effects of these conditions on cellular and molecular characteristics demand a serum-free alternative. Even though these limitations are well known and efforts for the development of adequate serum-free alternatives have been made, these approaches for replacement remained unsuccessful so far. This study aimed at developing a well-defined, serum-free formulation supporting both isolation from tissue samples and efficient expansion of PDL cells. Here, of particular focus was the perpetuation of tissue-characteristic markers detectable in primary tissues and of stemness features.

BASIC PROCEDURES

Primary PDL cell cultures from generally healthy human donors (n = 3) were maintained in basal media N2B27 and E6 together with different concentrations of growth and attachment factors. Cell proliferation was recorded via microscopy and WST assay. Gene expression of RUNX2, Periostin, ALP, CD73, CD90, CD105, CD45, SOX10 and SOX2 was compared to primary PDL explants via qRT-PCR. Immunocytochemistry was performed for anti-CD105, SSEA-3, CD271, HNK1. Serum-containing sDMEM medium served as control.

MAIN FINDINGS

N2B27 medium substituted with 25 ng/mL EGF, 25 ng/mL IGF1, 0.5 mg/mL Fetuin plus gelatine coating (designated N2B27-PDLsf) emerged as potent serum-free formulation ensuring adequate culture isolation and expansion. Here, PDL primary tissue signature markers RUNX2 and Periostin remained stable in N2B27-PDLsf compared to controls (229.0-fold ±101.0 and 83.2-fold ±9.6 increase). Additionally, stemness markers ALP and CD105 were significantly upregulated on transcriptional, and CD105 and SOX2 on protein level.

PRINCIPAL CONCLUSIONS

This investigation identified a novel serum-free medium for the isolation, and expansion of primary human PDL cells with constantly high proliferation rates. Here, purity and stemness properties are maintained. Thus, N2B27-PDLsf represents a valid replacement for serum-containing media in PDL cultures.

Marijuana-Derived Cannabinoids Trigger a CB2/PI3K Axis of Suppression of the Innate Response to Oral Pathogens

Cannabis use is an emergent risk factor for periodontitis, a chronic bacterial-induced disease of the supporting structures of the teeth. However, the mechanisms by which marijuana exposure predisposes to periodontal tissue destruction have yet to be elucidated. Therefore, we examined the influence of physiologically relevant doses of major marijuana-derived phytocannabinoid subtypes (cannabidiol [CBD]; cannabinol [CBN]; and tetrahydrocannabinol [THC], 1.0 μg/ml) on the interactions of three ultrastructurally variant oral pathogens, Porphyromonas gingivalis, Filifactor alocis, and Treponema denticola with the immune system. CBD, CBN, and THC each suppressed P. gingivalis-induced IL-12 p40, IL-6, IL-8, and TNF release while enhancing the anti-inflammatory cytokine, IL-10, from human innate cells. Similar phenomena were observed in F. alocis- and T. denticola-exposed human monocytes and human gingival keratinocytes. Higher phytocannabinoid doses (≥5.0 μg/ml) compromised innate cell viability and inhibited the growth of P. gingivalis and F. alocis, relative to unexposed bacteria. T. denticola, however, was resistant to all cannabinoid doses tested (up to 10.0 μg/ml). Pharmaceutical inhibition and efficient gene silencing indicated that a common CB2/PI3K axis of immune suppression is triggered by phytocannabinoids in vitro. This pathway does not appear to perpetuate through the canonical GSK3β-dependent cholinergic anti-inflammatory pathway, the predominant endogenous inflammatory control system. In a repetitive, transient oral infection model, CBD also suppressed P. gingivalis-induced innate immune markers in wild-type mice, but not in CB2^−/− mice. If such phenomena occur in humans in situ, environmental cannabinoids may enhance periodontitis via direct toxic effects on specific oral bacteria; by compromising innate cell vitality; and/or through a suppressed innate response to periodontal pathogens involving a CB2/PI3K signaling lineage.

CB1 enhanced the osteo/dentinogenic differentiation ability of periodontal ligament stem cells via p38 MAPK and JNK in an inflammatory environment

Objectives

Periodontitis is an inflammatory immune disease that causes periodontal tissue loss. Inflammatory immunity and bone metabolism are closely related to periodontitis. The cannabinoid receptor I (CB1) is an important constituent of the endocannabinoid system and participates in bone metabolism and inflammation tissue healing. It is unclear whether CB1 affects the mesenchymal stem cell (MSC) function involved in periodontal tissue regeneration. In this study, we revealed the role and mechanism of CB1 in the osteo/dentinogenic differentiation of periodontal ligament stem cells (PDLSCs) in an inflammatory environment.

Materials and methods

Alkaline phosphatase (ALP) activity, Alizarin Red staining, quantitative calcium analysis and osteo/dentinogenic markers were used to assess osteo/dentinogenic differentiation. Real‐time RT‐PCR and Western blotting were employed to detect gene expression.

Results

CB1 overexpression or CB1 agonist (10 µM R‐1 Meth) promoted the osteo/dentinogenic differentiation of PDLSCs. Deletion of CB1 or the application of CB1 antagonist (10 µM AM251) repressed the osteo/dentinogenic differentiation of PDLSCs. The activation of CB1 enhanced the TNF‐α‐ and INF‐γ‐impaired osteo/dentinogenic differentiation potential in PDLSCs. Moreover, CB1 activated p38 MAPK and JNK signalling and repressed PPAR‐γ and Erk1/2 signalling. Inhibition of JNK signalling could block CB1‐activated JNK and p38 MAPK signalling, while CB1 could activate p38 MAPK and JNK signalling, which was inhibited by TNF‐α and INF‐γ stimulation.

Conclusions

CB1 was able to enhance the osteo/dentinogenic differentiation ability of PDLSCs via p38 MAPK and JNK signalling in an inflammatory environment, which might be a potential target for periodontitis treatment.