Regulatory role of the endocannabinoid system on glial cells toward cognitive function in Alzheimer’s disease: A systematic review and meta-analysis of animal studies

Frontiers - Crunchbase Company Profile & Funding

“Objective: Over the last decade, researchers have sought to develop novel medications against dementia. One potential agent under investigation is cannabinoids. This review systematically appraised and meta-analyzed published pre-clinical research on the mechanism of endocannabinoid system modulation in glial cells and their effects on cognitive function in animal models of Alzheimer’s disease (AD). 

Methods: A systematic review complying with PRISMA guidelines was conducted. Six databases were searched: EBSCOHost, Scopus, PubMed, CINAHL, Cochrane, and Web of Science, using the keywords AD, cannabinoid, glial cells, and cognition. The methodological quality of each selected pre-clinical study was evaluated using the SYRCLE risk of bias tool. A random-effects model was applied to analyze the data and calculate the effect size, while I2 and p-values were used to assess heterogeneity. 

Results: The analysis included 26 original articles describing (1050 rodents) with AD-like symptoms. Rodents treated with cannabinoid agonists showed significant reductions in escape latency (standard mean difference [SMD] = -1.26; 95% confidence interval [CI]: -1.77 to -0.76, p < 0.00001) and ability to discriminate novel objects (SMD = 1.40; 95% CI: 1.04 to 1.76, p < 0.00001) compared to the control group. Furthermore, a significant decrease in Aβ plaques (SMD = -0.91; 95% CI: -1.55 to -0.27, p = 0.006) was observed in the endocannabinoid-treated group compared to the control group. Trends were observed toward neuroprotection, as represented by decreased levels of glial cell markers including glial fibrillary acid protein (SMD = -1.47; 95% CI: -2.56 to -0.38, p = 0.008) and Iba1 (SMD = -1.67; 95% CI: -2.56 to -0.79, p = 0.0002). Studies on the wild-type mice demonstrated significantly decreased levels of pro-inflammatory markers TNF-α, IL-1, and IL-6 (SMD = -2.28; 95% CI: -3.15 to -1.41, p = 0.00001). Despite the non-significant decrease in pro-inflammatory marker levels in transgenic mice (SMD = -0.47; 95% CI: -1.03 to 0.08, p = 0.09), the result favored the endocannabinoid-treated group over the control group. 

Conclusion: The revised data suggested that endocannabinoid stimulation promotes cognitive function via modulation of glial cells by decreasing pro-inflammatory markers in AD-like rodent models. Thus, cannabinoid agents may be required to modulate the downstream chain of effect to enhance cognitive stability against concurrent neuroinflammation in AD. Population-based studies and well-designed clinical trials are required to characterize the acceptability and real-world effectiveness of cannabinoid agents.”

https://pubmed.ncbi.nlm.nih.gov/36959856/

“Numerous traditional medical applications of cannabis have already been established and are now accepted practices in medicine.”

https://www.frontiersin.org/articles/10.3389/fphar.2023.1053680/full

The protective effect of cannabinoids against colorectal cancer cachexia through modulation of inflammation and immune responses

Biomedicine & Pharmacotherapy

“Cancer cachexia is a multifactorial disorder characterized by weight loss and muscle wasting, and there are currently no FDA-approved medications. In the present study, upregulation of six cytokines was observed in serum samples from patients with colorectal cancer (CRC) and in mouse models. A negative correlation between the levels of the six cytokines and body mass index in CRC patients was seen. Gene Ontology analysis revealed that these cytokines were involved in regulating T cell proliferation. The infiltration of CD8+ T cells was found to be associated with muscle atrophy in mice with CRC. Adoptive transfer of CD8+ T cells isolated from CRC mice resulted in muscle wasting in recipients.

The Genotype-Tissue Expression database showed that negative correlations between the expression of cachexia markers and cannabinoid receptor 2 (CB2) in human skeletal muscle tissues. Pharmacological treatment with Δ9-tetrahydrocannabinol (Δ9-THC), a selective CB2 agonist or overexpression of CB2 attenuated CRC-associated muscle atrophy. In contrast, knockout of CB2 with a CRISPR/Cas9-based strategy or depletion of CD8+ T cells in CRC mice abolished the Δ9-THC-mediated effects.

This study demonstrates that cannabinoids ameliorate CD8+ T cell infiltration in CRC-associated skeletal muscle atrophy via a CB2-mediated pathway. Serum levels of the six-cytokine signature might serve as a potential biomarker to detect the therapeutic effects of cannabinoids in CRC-associated cachexia.”

https://pubmed.ncbi.nlm.nih.gov/36871538/

“In recent years, researchers have gradually found that marijuana, in addition to recreational use, has potential applications as a supportive therapy or palliative medicine.

In conclusion, our findings indicate that the infiltration of CD8+ T cells in skeletal muscle plays a vital role in CRC-associated muscle atrophy. Treatment with Δ9-THC or CB65 can ameliorate CRC-associated cachexia and muscle atrophy by activating CB2 in CD8+ T cells. Targeting the CB2 receptor in CD8+ T cells should be evaluated as a therapeutic option for CRC patients who develop cachexia, and the six-cytokine signature in serum might serve as a potential biomarker for the therapeutic effects of cannabinoids in CRC-associated cachexia.”

https://www.sciencedirect.com/science/article/pii/S075333222300255X?via%3Dihub

The Anti-Tumorigenic Role of Cannabinoid Receptor 2 in Colon Cancer: A Study in Mice and Humans

ijms-logo

“The endocannabinoid system, particularly cannabinoid receptor 2 (CB2 in mice and CNR2 in humans), has controversial pathophysiological implications in colon cancer.

Here, we investigate the role of CB2 in potentiating the immune response in colon cancer in mice and determine the influence of CNR2 variants in humans. Comparing wild-type (WT) mice to CB2 knockout (CB2-/-) mice, we performed a spontaneous cancer study in aging mice and subsequently used the AOM/DSS model of colitis-associated colorectal cancer and a model for hereditary colon cancer (ApcMin/+). Additionally, we analyzed genomic data in a large human population to determine the relationship between CNR2 variants and colon cancer incidence.

Aging CB2-/- mice exhibited a higher incidence of spontaneous precancerous lesions in the colon compared to WT controls. The AOM/DSS-treated CB2-/- and ApcMin/+CB2-/- mice experienced aggravated tumorigenesis and enhanced splenic populations of immunosuppressive myeloid-derived suppressor cells along with abated anti-tumor CD8+ T cells. Importantly, corroborative genomic data reveal a significant association between non-synonymous variants of CNR2 and the incidence of colon cancer in humans.

Taken together, the results suggest that endogenous CB2 activation suppresses colon tumorigenesis by shifting the balance towards anti-tumor immune cells in mice and thus portray the prognostic value of CNR2 variants for colon cancer patients.”

https://pubmed.ncbi.nlm.nih.gov/36835468/

https://www.mdpi.com/1422-0067/24/4/4060

The Endocannabinoid System and Physical Exercise

ijms-logo

“The endocannabinoid system (ECS) is involved in various processes, including brain plasticity, learning and memory, neuronal development, nociception, inflammation, appetite regulation, digestion, metabolism, energy balance, motility, and regulation of stress and emotions.

Physical exercise (PE) is considered a valuable non-pharmacological therapy that is an immediately available and cost-effective method with a lot of health benefits, one of them being the activation of the endogenous cannabinoids.

Endocannabinoids (eCBs) are generated as a response to high-intensity activities and can act as short-term circuit breakers, generating antinociceptive responses for a short and variable period of time.

A runner’s high is an ephemeral feeling some sport practitioners experience during endurance activities, such as running. The release of eCBs during sustained physical exercise appears to be involved in triggering this phenomenon.

The last decades have been characterized by an increased interest in this emotional state induced by exercise, as it is believed to alleviate pain, induce mild sedation, increase euphoric levels, and have anxiolytic effects.

This review provides information about the current state of knowledge about endocannabinoids and physical effort and also an overview of the studies published in the specialized literature about this subject.”

https://pubmed.ncbi.nlm.nih.gov/36768332/

“PE is considered a valuable non-pharmacological therapy that is an immediately available and cost-effective method with many health benefits, one of them being the activation of endogenous cannabinoids to reduce stress and anxiety and improve wellness.”

https://www.mdpi.com/1422-0067/24/3/1989

“Exercise activates the endocannabinoid system”

https://pubmed.ncbi.nlm.nih.gov/14625449/

Endocannabinoids are potential inhibitors of glioblastoma multiforme proliferation

Journal of Integrative Medicine

“Globally, it is evident that glioblastoma multiforme (GBM) is an aggressive malignant cancer with a high mortality rate and no effective treatment options. Glioblastoma is classified as the stage-four progression of a glioma tumor, and its diagnosis results in a shortened life expectancy. Treatment options for GBM include chemotherapy, immunotherapy, surgical intervention, and conventional pharmacotherapy; however, at best, they extend the patient’s life by a maximum of 5 years. GBMs are considered incurable due to their high recurrence rate, despite various aggressive therapeutic approaches which can have many serious adverse effects.

Ceramides, classified as endocannabinoids, offer a promising novel therapeutic approach for GBM. Endocannabinoids may enhance the apoptosis of GBM cells but have no effect on normal healthy neural cells. Cannabinoids promote atypical protein kinase C, deactivate fatty acid amide hydrolase enzymes, and activate transient receptor potential vanilloid 1 (TRPV1) and TRPV2 to induce pro-apoptotic signaling pathways without increasing endogenous cannabinoids. In previous in vivo studies, endocannabinoids, chemically classified as amide formations of oleic and palmitic acids, have been shown to increase the pro-apoptotic activity of human cancer cells and inhibit cell migration and angiogenesis.

This review focuses on the biological synthesis and pharmacology of endogenous cannabinoids for the enhancement of cancer cell apoptosis, which have potential as a novel therapy for GBM.”

https://pubmed.ncbi.nlm.nih.gov/36805391/

“As discussed above, endocannabinoids could prove to be a viable alternative treatment for GBM.”

https://www.sciencedirect.com/science/article/abs/pii/S2095496423000055?via%3Dihub

A Retrospective Cohort Study That Examined the Impact of Cannabis Consumption on Long-Term Kidney Outcomes

View details for Cannabis and Cannabinoid Research cover image

“Background: Cannabis consumption for recreational and medical use is increasing worldwide. However, the long-term effects on kidney health and disease are largely unknown. 

Materials and Methods: Post hoc analysis of cannabis use as a risk factor for kidney disease was performed using data from the Assessment, Serial Evaluation, and Subsequent Sequelae of Acute Kidney Injury (ASSESS-AKI) study that enrolled hospitalized adults with and without acute kidney injury from four U.S. centers during 2009-2015. Associations between self-reported cannabis consumption and the categorical and continuous outcomes were determined using multivariable Cox regression and linear mixed models, respectively. 

Results: Over a mean follow-up of 4.5±1.8 years, 94 participants without chronic kidney disease (CKD) (estimated glomerular filtration rate [eGFR] >60 mL/min/1.73 m2) who consumed cannabis had similar rates of annual eGFR decline versus 889 nonconsumers (mean difference=-0.02 mL/min/1.73 m2/year, p=0.9) and incident CKD (≥25% reduction in eGFR compared with the 3-month post-hospitalization measured eGFR and achieving CKD stage 3 or higher) (adjusted hazard ratio [aHR]=1.2; 95% confidence interval [CI]=0.7-2.0). Nineteen participants with CKD (eGFR <60 mL/min/1.73 m2) who consumed cannabis had more rapid eGFR decline versus 597 nonconsumers (mean difference=-1.3 mL/min/1.73 m2/year; p=0.02) that was not independently associated with an increased risk of CKD progression (≥50% reduction in eGFR compared with the 3-month post-hospitalization eGFR, reaching CKD stage 5, or receiving kidney replacement therapy) (aHR=1.6; 95% CI=0.7-3.5). Cannabis consumption was not associated with the rate of change in urine albumin to creatinine ratio (UACR) over time among those with (p=0.7) or without CKD (p=0.4). 

Conclusions: Cannabis consumption did not adversely affect the kidney function of participants without CKD but was associated with a faster annual eGFR decline among participants with CKD. Cannabis consumption was not associated with changes in UACR over time, incident CKD, or progressive CKD regardless of baseline kidney function. Additional research is needed to investigate the kidney endocannabinoid system and the impact of cannabis use on kidney disease outcomes.”

https://pubmed.ncbi.nlm.nih.gov/36791309/

https://www.liebertpub.com/doi/10.1089/can.2022.0141

Role of Gut Microbiota in Cannabinoid-Mediated Suppression of Inflammation

Frontiers Publishing Partnerships on Twitter: "Become a reviewer for  Advances in Drug and Alcohol Research, the official journal of IDARS &  @INRCmeeting! Explore cutting edge research and help us promote  #OpenScience #OpenAccess

“Cannabinoids and the endocannabinoid system have been well established to play a crucial role in the regulation of the immune response. Also, emerging data from numerous investigations unravel the imperative role of gut microbiota and their metabolites in the maintenance of immune homeostasis and gut barrier integrity. In this review, we concisely report the immunosuppressive mechanisms triggered by cannabinoids, and how they are closely associated with the alterations in the gut microbiome and metabolome following exposure to endogenous or exogenous cannabinoids. We discuss how cannabinoid-mediated induction of microbial secondary bile acids, short chain fatty acids, and indole metabolites, produced in the gut, can suppress inflammation even in distal organs. While clearly, more clinical studies are necessary to establish the cross talk between exo- or endocannabinoid system with the gut microbiome and the immune system, the current evidence opens a new avenue of cannabinoid-gut-microbiota-based therapeutics to regulate immunological disorders.”

https://pubmed.ncbi.nlm.nih.gov/36776218/

“The microbiome-eCB signaling modulation exploiting exo- or endogenous cannabinoids opens a new avenue of cannabinoid-gut microbiota-based therapeutics to curb metabolic and immune-oriented conditions.”

https://www.frontierspartnerships.org/articles/10.3389/adar.2022.10550/full

Rare Phytocannabinoids Exert Anti-Inflammatory Effects on Human Keratinocytes via the Endocannabinoid System and MAPK Signaling Pathway

ijms-logo

“Increasing evidence supports the therapeutic potential of rare cannabis-derived phytocannabinoids (pCBs) in skin disorders such as atopic dermatitis, psoriasis, pruritus, and acne. However, the molecular mechanisms of the biological action of these pCBs remain poorly investigated.

In this study, an experimental model of inflamed human keratinocytes (HaCaT cells) was set up by using lipopolysaccharide (LPS) in order to investigate the anti-inflammatory effects of the rare pCBs cannabigerol (CBG), cannabichromene (CBC), Δ9-tetrahydrocannabivarin (THCV) and cannabigerolic acid (CBGA). To this aim, pro-inflammatory interleukins (IL)-1β, IL-8, IL-12, IL-31, tumor necrosis factor (TNF-β) and anti-inflammatory IL-10 levels were measured through ELISA quantification. In addition, IL-12 and IL-31 levels were measured after treatment of HaCaT cells with THCV and CBGA in the presence of selected modulators of endocannabinoid (eCB) signaling. In the latter cells, the activation of 17 distinct proteins along the mitogen-activated protein kinase (MAPK) pathway was also investigated via Human Phosphorylation Array.

Our results demonstrate that rare pCBs significantly blocked inflammation by reducing the release of all pro-inflammatory ILs tested, except for TNF-β. Moreover, the reduction of IL-31 expression by THCV and CBGA was significantly reverted by blocking the eCB-binding TRPV1 receptor and by inhibiting the eCB-hydrolase MAGL. Remarkably, THCV and CBGA modulated the expression of the phosphorylated forms (and hence of the activity) of the MAPK-related proteins GSK3β, MEK1, MKK6 and CREB also by engaging eCB hydrolases MAGL and FAAH.

Taken together, the ability of rare pCBs to exert an anti-inflammatory effect in human keratinocytes through modifications of eCB and MAPK signaling opens new perspectives for the treatment of inflammation-related skin pathologies.”

https://pubmed.ncbi.nlm.nih.gov/36769042/

“Overall, this proof of concept, which shows that in inflamed human keratinocytes, rare pCBs can indeed interact with specific eCB system elements, opens new perspectives for possible treatments of inflammation-related skin diseases. Incidentally, such interactions between pCBs and eCB system seems to hold therapeutic potential well beyond the skin, such as possible treatments reported for autism spectrum disorders and cancer”

https://www.mdpi.com/1422-0067/24/3/2721

“Effects of Rare Phytocannabinoids on the Endocannabinoid System of Human Keratinocytes”

https://pubmed.ncbi.nlm.nih.gov/35628241/

Cannabinoids in the Modulation of Oxidative Signaling

ijms-logo

“Cannabis sativa-derived compounds, such as delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), and components of the endocannabinoids system, such as N-arachidonoylethanolamide (anandamide, AEA) and 2-arachidonoylglycerol (2-AG), are extensively studied to investigate their numerous biological effects, including powerful antioxidant effects. Indeed, a series of recent studies have indicated that many disorders are characterized by alterations in the intracellular antioxidant system, which lead to biological macromolecule damage. These pathological conditions are characterized by an unbalanced, and most often increased, reactive oxygen species (ROS) production.

For this study, it was of interest to investigate and recapitulate the antioxidant properties of these natural compounds, for the most part CBD and THC, on the production of ROS and the modulation of the intracellular redox state, with an emphasis on their use in various pathological conditions in which the reduction of ROS can be clinically useful, such as neurodegenerative disorders, inflammatory conditions, autoimmunity, and cancers. The further development of ROS-based fundamental research focused on cannabis sativa-derived compounds could be beneficial for future clinical applications.”

https://pubmed.ncbi.nlm.nih.gov/36768835/

“In conclusion, it has been reported that cannabinoids modulate oxidative stress in inflammation and autoimmunity, which makes them a potential therapeutic approach for different kinds of pathologies.”

https://www.mdpi.com/1422-0067/24/3/2513

The evolution of cannabinoid receptors in cancer

“Cannabis sativa (cannabis) has been used as a therapeutic treatment for centuries treating various diseases and disorders. However, racial propaganda led to the criminalization of cannabis in the 1930s preventing opportunities to explore marijuana in therapeutic development. The increase in recreational use of cannabis further grew concern about abuse, and lead to further restrictions and distribution of cannabis in the 1970s when it was declared to be a Schedule I drug in the USA. In the late 1990s in some states, legislation assisted in legalizing the use of cannabis for medical purposes under physician supervision.

As it has been proven that cannabinoids and their receptors play an essential role in the regulation of the physiological and biological processes in our bodies. The endocannabinoid system (ECS) is the complex that regulates the cell-signaling system consisting of endogenous cannabinoids (endocannabinoids), cannabinoid receptors, and the enzymes responsible for the synthesis and degradation of the endocannabinoids. The ECS along with phytocannabinoids and synthetic cannabinoids serves to be a beneficial therapeutic target in treating diseases as they play roles in cell homeostasis, cell motility, inflammation, pain-sensation, mood, and memory.

Cannabinoids have been shown to inhibit proliferation, metastasis, and angiogenesis and even restore homeostasis in a variety of models of cancer in vitro and in vivo. Cannabis and its receptors have evolved into a therapeutic treatment for cancers.”

https://pubmed.ncbi.nlm.nih.gov/36750231/

https://wires.onlinelibrary.wiley.com/doi/10.1002/wsbm.1602