Δ9 -Tetrahydrocannabinolic acid alleviates collagen-induced arthritis: Role of PPARγ and CB1 receptors

Endocannabinoid System Receptors at the Hip and Stifle Joints of Middle-Aged Dogs: A Novel Target for the Therapeutic Use of Cannabis sativa Extract in Canine Arthropathies

The endocannabinoid system (ECS) has emerged as a potential therapeutic target in veterinary medicine due to its involvement in a wide range of physiological processes including pain, inflammation, immune function, and neurological function. Modulation of the ECS receptors has been shown to have anti-inflammatory, analgesic, and immunomodulatory effects in various animal models of disease, including dogs with osteoarthritis. The goal of this study was to identify and compare the cellular expression and distribution of cannabinoid receptor type 1 (CB1R) and type 2 (CB2R) and the cannabinoid-related G protein-coupled receptor 55 (GPR55) on the synovial cells of hip and stifle joints of seven dogs of different breeds without overt signs of osteoarthritis (OA). The synovial membranes of seven hips and seven stifle joints were harvested post mortem. The expression of the CB1R, CB2R, and GPR55 present in the synovial tissues was investigated using qualitative and quantitative immunofluorescence and Western blot (Wb) analysis. Synoviocytes of the stifle and hip joints expressed CB1R, CB2R, and GPR55 immunoreactivity (IR); no significant differences were observed for each different joint. Cannabinoid receptor 2- and GPR55-IR were also expressed by macrophages, neutrophils, and vascular cells. The ECS receptors were widely expressed by the synovial elements of dogs without overt signs of OA. It suggests that the ECS could be a target for the therapeutic use of Cannabis sativa extract in canine arthropathies.

Targeting the endocannabinoid system: Structural determinants and molecular mechanism of allosteric modulation

Although drugs targeting the orthosteric binding site of cannabinoid receptors (CBRs) have several therapeutic effects on human physiological and pathological conditions, they can also cause serious adverse effects. Only a few orthosteric ligands have successfully passed clinical trials. Recently, allosteric modulation has become a novel option for drug discovery, with fewer adverse effects and the potential to avoid drug overdose. In this review, we highlight novel findings related to the drug discovery of allosteric modulators (AMs) targeting CBRs. We summarize newly synthesized AMs and the reported/predicted allosteric binding sites. We also discuss the structural determinants of the AMs binding as well as the molecular mechanism of CBR allostery.

Endocannabinoid-Binding Receptors as Drug Targets

Cannabis plant has been used from ancient times with therapeutic purposes for treating human pathologies, but the identification of the cellular and molecular mechanisms underlying the therapeutic properties of the phytocannabinoids, the active compounds in this plant, occurred in the last years of the past century. In the late 1980s and early 1990s, seminal studies demonstrated the existence of cannabinoid receptors and other elements of the so-called endocannabinoid system. These G protein-coupled receptors (GPCRs) are a key element in the functions assigned to endocannabinoids and appear to serve as promising pharmacological targets. They include CB₁, CB₂, and GPR55, but also non-GPCRs can be activated by endocannabinoids, like ionotropic receptor TRPV₁ and even nuclear receptors of the PPAR family. Their activation, inhibition, or simply modulation have been associated with numerous physiological effects at both central and peripheral levels, which may have therapeutic value in different human pathologies, then providing a solid experimental explanation for both the ancient medicinal uses of Cannabis plant and the recent advances in the development of cannabinoid-based specific therapies. This chapter will review the scientific knowledge generated in the last years around the research on the different endocannabinoid-binding receptors and their signaling mechanisms. Our intention is that this knowledge may help readers to understand the relevance of these receptors in health and disease conditions, as well as it may serve as the theoretical basis for the different experimental protocols to investigate these receptors and their signaling mechanisms that will be described in the following chapters.

Analysis of Anti-Cancer and Anti-Inflammatory Properties of 25 High-THC Cannabis Extracts

Cannabis sativa is one of the oldest cultivated plants. Many of the medicinal properties of cannabis are known, although very few cannabis-based formulations became prescribed drugs. Previous research demonstrated that cannabis varieties are very different in their medicinal properties, likely due to the entourage effect-the synergistic or antagonistic effect of various cannabinoids and terpenes. In this work, we analyzed 25 cannabis extracts containing high levels of delta-9-tetrahydrocannabinol (THC). We used HCC1806 squamous cell carcinoma and demonstrated various degrees of efficiency of the tested extracts, from 66% to 92% of growth inhibition of cancer cells. Inflammation was tested by induction of inflammation with TNF-α/IFN-γ in WI38 human lung fibroblasts. The efficiency of the extracts was tested by analyzing the expression of COX2 and IL6; while some extracts aggravated inflammation by increasing the expression of COX2/IL6 by 2-fold, other extracts decreased inflammation, reducing expression of cytokines by over 5-fold. We next analyzed the level of THC, CBD, CBG and CBN and twenty major terpenes and performed clustering and association analysis between the chemical composition of the extracts and their efficiency in inhibiting cancer growth and curbing inflammation. A positive correlation was found between the presence of terpinene (pval = 0.002) and anti-cancer property; eucalyptol came second, with pval of 0.094. p-cymene and β-myrcene positively correlated with the inhibition of IL6 expression, while camphor correlated negatively. No significant correlation was found for COX2. We then performed a correlation analysis between cannabinoids and terpenes and found a positive correlation for the following pairs: α-pinene vs. CBD, p-cymene vs. CBGA, terpenolene vs. CBGA and isopulegol vs. CBGA. Our work, thus, showed that most of high-THC extracts demonstrate anti-cancer activity, while only certain selected extracts showed anti-inflammatory activity. Presence of certain terpenes, such as terpinene, eucalyptol, cymene, myrcene and camphor, appear to have modulating effects on the activity of cannabinoids.

Similarities and differences upon binding of naturally occurring Δ9-tetrahydrocannabinol-derivatives to cannabinoid CB1 and CB2 receptors

We have here assessed, using Δ⁹-tetrahydrocannabinol (Δ⁹-THC) for comparison, the effect of Δ⁹-tetrahydrocannabinolic acid (Δ⁹-THCA) and of Δ⁹-tetrahydrocannabivarin (Δ9-THCV) that is mediated by human versions of CB₁, CB₂, and CB₁-CB₂ receptor functional units, expressed in a heterologous system. Binding to the CB₁ and CB₂ receptors was addressed in living cells by means of a homogeneous assay. A biphasic competition curve for the binding to the CB₂ receptor, was obtained for Δ⁹-THCV in cells expressing the two receptors. Signaling studies included cAMP level determination, activation of the mitogen-activated protein kinase pathway and ß-arrestin recruitment were performed. The signaling triggered by Δ⁹-THCA and Δ⁹-THCV via individual receptors or receptor heteromers disclosed differential bias, i.e. the bias observed using a given phytocannabinoid depended on the receptor (CB₁, CB₂ or CB₁-CB₂) and on the compound used as reference to calculate the bias factor (Δ⁹-THC, a selective agonist or a non-selective agonist). These results are consistent with different binding modes leading to differential functional selectivity depending on the agonist structure, and the state (monomeric or heteromeric) of the cannabinoid receptor. In addition, on studying Gi-coupling we showed that Δ⁹-THCV and Δ⁹-THCA and Δ⁹-THCV were able to revert the effect of a selective CB₂ receptor agonist, but only Δ9-THCV, and not Δ9-THCA, reverted the effect of arachidonyl-2'-chloroethylamide (ACEA 100 nM) a selective agonist of the CB₁ receptor. Overall, these results indicate that cannabinoids may have a variety of binding modes that results in qualitatively different effects depending on the signaling pathway that is engaged upon cannabinoid receptor activation.

Topical Use of Cannabis sativa L. Biochemicals

Cannabis sativa L. plant is currently attracting increasing interest in cosmetics and dermatology. In this review, the biologically active compounds of hemp are discussed. Particularly the complex interactions of cannabinoids with the endocannabinoid system of the skin to treat various conditions (such as acne, allergic contact dermatitis, melanoma, and psoriasis) with clinical data. Moreover, the properties of some cannabinoids make them candidates as cosmetic actives for certain skin types. Hemp seed oil and its minor bioactive compounds such as terpenes, flavonoids, carotenoids, and phytosterols are also discussed for their added value in cosmetic formulation.

Molecular Targets of Cannabinoids Associated with Depression

Novel therapeutic strategies are needed to address depression, a major neurological disorder affecting hundreds of millions of people worldwide. Cannabinoids and their synthetic derivatives have demonstrated numerous neurological activities and may potentially be developed into new treatments for depression. This review highlights cannabinoid (CB) receptors, monoamine oxidase (MAO), N-methyl-D-aspartate (NMDA) receptor, gamma-aminobutyric acid (GABA) receptor, and cholecystokinin (CCK) receptor as key molecular targets of cannabinoids that are associated with depression. The anti-depressant activity of cannabinoids and their binding modes with cannabinoid receptors are discussed, providing insights into rational design and discovery of new cannabinoids or cannabimimetic agents with improved druggable properties.

Relevance of Peroxisome Proliferator Activated Receptors in Multitarget Paradigm Associated with the Endocannabinoid System

Cannabinoids have shown to exert their therapeutic actions through a variety of targets. These include not only the canonical cannabinoid receptors CB1R and CB2R but also related orphan G protein-coupled receptors (GPCRs), ligand-gated ion channels, transient receptor potential (TRP) channels, metabolic enzymes, and nuclear receptors. In this review, we aim to summarize reported compounds exhibiting their therapeutic effects upon the modulation of CB1R and/or CB2R and the nuclear peroxisome proliferator-activated receptors (PPARs). Concomitant actions at CBRs and PPARα or PPARγ subtypes have shown to mediate antiobesity, analgesic, antitumoral, or neuroprotective properties of a variety of phytogenic, endogenous, and synthetic cannabinoids. The relevance of this multitargeting mechanism of action has been analyzed in the context of diverse pathologies. Synergistic effects triggered by combinatorial treatment with ligands that modulate the aforementioned targets have also been considered. This literature overview provides structural and pharmacological insights for the further development of dual cannabinoids for specific disorders.

Δ9-Tetrahydrocannabinolic Acid markedly alleviates liver fibrosis and inflammation in mice

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in the Western world, and it is closely associated to obesity, type 2 diabetes mellitus, and dyslipidemia. Medicinal cannabis and some neutral cannabinoids have been suggested as a potential therapy for liver diseases.

HYPOTHESIS

Δ⁹-tetrahydrocannabinolic acid (Δ⁹-THCA), the non-psychotropic precursor of Δ⁹-THC, is one of the most abundant cannabinoids presents in Cannabis Sativa. However, its biological activities have been poorly investigated. Herein, we studied the antifibrotic and antiinflammatory activities of Δ⁹-THCA in two different animal models of liver injury, providing a rationale for additional studies on the medicinal use of this cannabinoid in the treatment of liver fibrosis and the management of NAFLD.

STUDY DESIGN

The antifibrotic activity of Δ⁹-THCA in vitro was investigated in the cell lines LX-2 and NIH-3T3-Col1A2-luc. Non-alcoholic liver fibrosis was induced in mice by CCl₄ treatment or, alternatively, by 23-week high fat diet (HFD) feeding. Δ⁹-THCA was administered daily intraperitoneally during the CCl₄ treatment or during the last 3 weeks in HFD-fed mice.

METHODS

TGFβ-induced profibrotic gene expression was analyzed by luciferase and qPCR assays. Liver fibrosis and inflammation were assessed by immunochemistry and qPCR. Blood glucose, insulin, leptin and triglyceride levels were measured in HFD mice.

RESULTS

Δ⁹-THCA inhibited the expression of Tenascin C (TNC) and Col3A1 induced by TGFβ in LX-2 cells and the transcriptional activity of the Col1A2 promoter in fibroblasts. Δ⁹-THCA significantly attenuated CCl₄-induced liver fibrosis and inflammation and reduced T cell and macrophage infiltration. Mice fed HFD for 23 weeks developed severe obesity (DIO), fatty liver and marked liver fibrosis, accompanied by immune cell infiltration. Δ⁹-THCA, significantly reduced body weight and adiposity, improved glucose tolerance, and drastically attenuated DIO-induced liver fibrosis and immune cell infiltration.

CONCLUSIONS

Δ⁹-THCA prevents TGFβ-induced fibrotic markers in vitro and liver inflammation and fibrogenesis in vivo, providing a rationale for additional studies on the medicinal use of this cannabinoid, as well as cannabis preparations containing it, for the treatment of liver fibrosis and the management of NAFLD.

Evaluation of the Possible Anticonvulsant Effect of Δ9-Tetrahydrocannabinolic Acid in Murine Seizure Models

Introduction: The cannabinoid Δ⁹-tetrahydrocannabinolic acid (Δ⁹-THCA) has long been suggested in review articles and anecdotal reports to be anticonvulsant; yet, there is scant evidence supporting this notion. The objective of this study was to interrogate the anticonvulsant potential of Δ⁹-THCA in various seizure models—the Scn1a^+/− mouse model of Dravet syndrome, the 6-Hz model of psychomotor seizures and the maximal electroshock (MES) model of generalized tonic-clonic seizures.

Materials and Methods: We examined the effect of acute Δ⁹-THCA treatment against hyperthermia-induced seizures, and subchronic treatment on spontaneous seizures and survival in the Scn1a^+/− mice. We also studied the effect of acute Δ⁹-THCA treatment on the critical current thresholds in the 6-Hz and MES tests using outbred Swiss mice. Highly purified Δ⁹-THCA was used in the studies or a mixture of Δ⁹-THCA and Δ⁹-THC.

Results: We observed mixed anticonvulsant and proconvulsant effects of Δ⁹-THCA across the seizure models. Highly pure Δ⁹-THCA did not affect hyperthermia-induced seizures in Scn1a^+/− mice. A Δ⁹-THCA/Δ⁹-THC mixture was anticonvulsant in the 6-Hz threshold test, but purified Δ⁹-THCA and Δ⁹-THC had no effect. Conversely, both Δ⁹-THCA and Δ⁹-THC administered individually were proconvulsant in the MES threshold test but had no effect when administered as a Δ⁹-THCA/Δ⁹-THC mixture. The Δ⁹-THCA/Δ⁹-THC mixture, however, increased spontaneous seizure severity and increased mortality of Scn1a^+/− mice.

Discussion: The anticonvulsant profile of Δ⁹-THCA was variable depending on the seizure model used and presence of Δ⁹-THC. Because of the unstable nature of Δ⁹-THCA, further exploration of Δ⁹-THCA through formal anticonvulsant drug development is problematic without stabilization. Future studies may better focus on determining the mechanisms by which combined Δ⁹-THCA and Δ⁹-THC alters seizure thresholds, as this may uncover novel targets for the control of refractory partial seizures.

Δ9 -Tetrahydrocannabinolic acid alleviates collagen-induced arthritis: Role of PPARγ and CB1 receptors

BACKGROUND AND PURPOSE

Δ⁹ -Tetrahydrocannabinolic acid (Δ⁹ -THCA-A), the precursor of Δ⁹ -THC, is a non-psychotropic phytocannabinoid that shows PPARγ agonist activity. Here, we investigated the ability of Δ⁹ -THCA-A to modulate the classic cannabinoid CB₁ and CB₂ receptors and evaluated its anti-arthritis activity in vitro and in vivo.

EXPERIMENTAL APPROACH

Cannabinoid receptors binding and intrinsic activity, as well as their downstream signalling, were analysed in vitro and in silico. The anti-arthritis properties of Δ⁹ -THCA-A were studied in human chondrocytes and in the murine model of collagen-induced arthritis (CIA). Plasma disease biomarkers were identified by LC-MS/MS based on proteomic and elisa assays.

KEY RESULTS

Functional and docking analyses showed that Δ⁹ -THCA-A can act as an orthosteric CB₁ receptor agonist and also as a positive allosteric modulator in the presence of CP-55,940. Also, Δ⁹ -THCA-A seemed to be an inverse agonist for CB₂ receptors. In vivo, Δ⁹ -THCA-A reduced arthritis in CIA mice, preventing the infiltration of inflammatory cells, synovium hyperplasia, and cartilage damage. Furthermore, Δ⁹ -THCA-A inhibited expression of inflammatory and catabolic genes on knee joints. The anti-arthritic effect of Δ⁹ -THCA-A was blocked by either SR141716 or T0070907. Analysis of plasma biomarkers, and determination of cytokines and anti-collagen antibodies confirmed that Δ⁹ -THCA-A mediated its activity mainly through PPARγ and CB₁ receptor pathways.

CONCLUSION AND IMPLICATIONS

Δ⁹ -THCA-A modulates CB₁ receptors through the orthosteric and allosteric binding sites. In addition, Δ⁹ -THCA-A exerts anti-arthritis activity through CB₁ receptors and PPARγ pathways, highlighting its potential for the treatment of chronic inflammatory diseases such as rheumatoid arthritis.