Role of cannabinoid receptors in hepatic fibrosis and apoptosis associated with bile duct ligation in rats

Hepatoprotective effect of astaxanthin against cholestasis liver fibrosis induced by bile duct ligation in adult Wistar rats

In this study, we evaluated the hepatoprotective effects of astaxanthin, a natural carotenoid, against the cholestatic liver fibrosis induced by bile duct ligation (BDL). Toward this end, male rats were subjected to BDL and treated with astaxanthin for 35 days. Afterwards, their serum and liver biochemical factors were assessed. Also, histopathological and immunohistochemical analyses were performed to determine the fibrosis and the expression levels of alpha-smooth muscle actin (α-SMA) and transforming growth factor beta (TGF-ß1) in the liver tissue. Based on the results, BDL caused a significant increase in liver enzyme levels, blood lipids, and bilirubin, while decreasing the activity of superoxide dismutase(SOD), catalase (CAT), and glutathione (GSH) enzymes. Also, in the BDL rats, hepatocyte necrosis, infiltration of inflammatory lymphocytes, and hyperplasia of bile ducts were detected, along with a significant increase in α-SMA and TGF-ß1 expression. Astaxanthin, however, significantly prevented the BDL's detrimental effects. In all, 10 mg/kg of this drug maintained the bilirubin and cholesterol serum levels of BDL rats at normal levels. It also reduced the liver enzymes' activity and serum lipids, while increasing the SOD, CAT, and GSH activity in BDL rats. The expression of α-SMA and TGF-ß1 in the BDL rats treated with 10 mg/kg of astaxanthin was moderate (in 34%-66% of cells) and no considerable cholestatic fibrosis was observed in this group. However, administrating the 20 mg/kg of astaxanthin was not effective in this regard. These findings showed that astaxanthin could considerably protect the liver from cholestatic damage by improving the biochemical features and regulating the expression of related proteins.

Exploring the therapeutic potential of natural compounds modulating the endocannabinoid system in various diseases and disorders: review

Cannabinoid receptors, endogenous cannabinoids (endocannabinoids), and the enzymes involved in the biosynthesis and degradation of the endocannabinoids make up the endocannabinoid system (ECS). The components of the ECS are proven to modulate a vast bulk of various physiological and pathological processes due to their abundance throughout the human body. Such discoveries have attracted the researchers' attention and emerged as a potential therapeutical target for the treatment of various diseases. In the present article, we reviewed the discoveries of natural compounds, herbs, herbs formula, and their therapeutic properties in various diseases and disorders by modulating the ECS. We also summarize the molecular mechanisms through which these compounds elicit their properties by interacting with the ECS based on the existing findings. Our study provides the insight into the use of natural compounds that modulate ECS in various diseases and disorders, which in turn may facilitate future studies exploiting natural lead compounds as novel frameworks for designing more effective and safer therapeutics.

Cannabinoid Receptor Type II Ligands from Sandalwood Oil and Synthetic α-Santalol Derivatives

Bioassay-guided fractionation of the essential oil of Santalum album led to the identification of α-santalol (1) and β-santalol (2) as new chemotypes of cannabinoid receptor type II (CB2) ligands with Ki values of 10.49 and 8.19 μM, respectively. Nine structurally new α-santalol derivatives (4a-4h and 5) were synthesized to identify more selective and potent CB2 ligands. Compound 4e with a piperazine structural moiety demonstrated a Ki value of 0.99 μM against CB2 receptor and did not show binding activity against cannabinoid receptor type I (CB1) at 10 μM. Compounds 1, 2, and 4e increased intracellular calcium influx in SH-SY5Y human neuroblastoma cells that were attenuated by CB2 antagonism or inverse agonism, supporting the results that these compounds are CB2 agonists. Molecular docking showed that 1 and 4e had similar binding poses, exhibiting a unique interaction with Thr114 within the CB2 receptor, and that the piperazine structural moiety is required for the binding affinity of 4e. A 200 ns molecular dynamics simulation of CB2 complexed with 4e confirmed the stability of the complex. This structural insight lays a foundation to further design and synthesize more potent and selective α-santalol-based CB2 ligands for drug discovery.

Beta Caryophyllene-Loaded Nanostructured Lipid Carriers for Topical Management of Skin Disorders: Statistical Optimization, In Vitro and Dermatokinetic Evaluation

This work aimed to overcome the disadvantages of the oral administration of beta-caryophyllene and boost efficiency by developing a nanostructured lipid carrier for topical administration of the drug in skin disorders. The heat emulsification method was utilized to produce beta-caryophyllene-loaded nanostructured lipid carriers. The newly created formulation was examined for its particle size, entrapment efficiency, and zeta potential after being improved using the Box-Behnken Design. The chosen formulation underwent tests to determine its ex vivo skin retention, dermatokinetic, in vitro release, antioxidant, and confocal laser scanning microscopy study. The findings of the characterization of the nanostructured lipid carriers demonstrated that the particles had a spherical form and a size of 210.86 nm (0.263 polydispersity index). The entrapment efficiency was determined to be 86.74%, and the zeta potential was measured to be -26.97 mV. The in vitro release investigation showed that nanostructure lipid carriers were capable of releasing regulated amounts of beta-caryophyllene for up to 24 hrs. In comparison to the traditional gel formulation, the ex vivo investigation demonstrated a 1.94-fold increase in the skin's capacity to retain the substance. According to the findings of the study, nanostructure lipid carriers loaded with beta-caryophyllene have the potential to be investigated for use as a topical administration method in skin disorders with enhanced skin retention and effectiveness.

Current advances on the therapeutic potential of pinocembrin: An updated review

Pinocembrin (5,7-dihydroxyflavone) is a major flavonoid found in many plants, fungi and hive products, mainly honey and propolis. Several in vitro and preclinical studies revealed numerous pharmacological activities of pinocembrin including antioxidant, anti-inflammatory, antimicrobial, neuroprotective, cardioprotective and anticancer activities. Here, we comprehensively review and critically analyze the studies carried out on pinocembrin. We also discuss its potential mechanisms of action, bioavailability, toxicity, and clinical investigations. The wide therapeutic window of pinocembrin makes it a promising drug candidate for many clinical applications. We recommend some future perspectives to improve its pharmacokinetic and pharmacodynamic properties for better delivery that may also lead to new therapeutic advances.

MiR-22-3p and miR-29a-3p synergistically inhibit hepatic stellate cell activation by targeting AKT3

Hepatic fibrosis (HF) is a worldwide health problem for which there is no medically effective drug treatment at present, and which is characterized by activation of hepatic stellate cells (HSCs) and excessive extracellular matrix (ECM) deposition. The HF model in cholestatic rats by ligating the common bile duct was induced and the differentially expressed miRNAs in the liver tissues were analyzed by microarray, which showed that miR-22-3p and miR-29a-3p were significantly downregulated in bile-duct ligation (BDL) rat liver compared with the sham control. The synergistic anti-HF activity and molecular mechanism of miR-22-3p and miR-29a-3p by targeting AKT serine/threonine kinase 3 (AKT3) in HSCs were explored. The expression levels of miR-22-3p and miR-29a-3p were downregulated in activated LX-2 and human primary normal hepatic fibroblasts (NFs), whereas AKT3 was found to be upregulated in BDL rat liver and activated LX-2 cells. The proliferation, colony-forming, and migration ability of LX-2 were inhibited synergistically by miR-22-3p and miR-29a-3p. In addition, cellular senescence was induced and the expressions of the LX-2 fibrosis markers COL1A1 and α-SMA were inhibited by miR-22-3p and miR-29a-3p synergistically. Subsequently, these two miRNAs binding to the 3'UTR of AKT3 mRNA was predicted and evidenced by the luciferase reporter assay. Furthermore, the proliferation, migration, colony-forming ability, and the expression levels of COL1A1 and α-SMA were promoted and cellular senescence was inhibited by AKT3 in LX-2 cells. Thus, miR-22-3p/miR-29a-3p/AKT3 regulates the activation of HSCs, providing a new avenue in the study and treatment of HF.

AabHLH112, a bHLH transcription factor, positively regulates sesquiterpenes biosynthesis in Artemisia annua

The bHLH transcription factors play important roles in the regulation of plant growth, development, and secondary metabolism. β-Caryophyllene, epi-cedrol, and β-farnesene, three kinds of sesquiterpenes mainly found in plants, are widely used as spice in the food industry and biological pesticides in agricultural production. Furthermore, they also have a significant value in the pharmaceutical industry. However, there is currently a lack of knowledge on the function of bHLH family TFs in β-caryophyllene, epi-cedrol, and β-farnesene biosynthesis. Here, we found that AabHLH112 transcription factor had a novel function to positively regulate β-carophyllene, epi-cedrol, and β-farnesene biosynthesis in Artemisia annua. Exogenous MeJA enhanced the expression of AabHLH112 and genes of β-caryophyllene synthase (CPS), epi-cedrol synthase (ECS), and β-farnesene synthase (BFS), as well as sesquiterpenes content. Dual-LUC assay showed the activation of AaCPS, AaECS, and AaBFS promoters were enhanced by AabHLH112. Yeast one-hybrid assay showed AabHLH112 could bind to the G-box (CANNTG) cis-element in promoters of both AaCPS and AaECS. In addition, overexpression of AabHLH112 in A. annua significantly elevated the expression levels of AaCPS, AaECS, and AaBFS as well as the contents of β-caryophyllene, epi-cedrol, and β-farnesene, while suppressing AabHLH112 expression by RNAi reduced the expression of the three genes and the contents of the three sesquiterpenes. These results suggested that AabHLH112 is a positive regulator of β-caryophyllene, epi-cedrol, and β-farnesene biosynthesis in A. annua.

β-Caryophyllene promotes oxidative stress and apoptosis in KB cells through activation of mitochondrial-mediated pathway - An in-vitro and in-silico study

Beta-caryophyllene (BCP), are natural bicyclic sesquiterpenes which are present in numerous plants worldwide. BCP has antioxidant, antimicrobial, and antifungal properties. Here, we studied its anticancer, anti-inflammatory, and cytotoxic effects. Cells treated with BCP, in a dose-dependent manner, exhibited morphological changes, showed lower cell growth, underwent apoptosis and lost the ability to metastasis through the suppression of NF-ҡ B via PI3K/AKT signalling pathway. These results elucidate that the inhibition of NF-ҡ B and PI3K/AKT is one of the most important mechanism by which BCP suppresses cancer cell proliferation and enhances apoptosis.

A focused review on CB2 receptor-selective pharmacological properties and therapeutic potential of β-caryophyllene, a dietary cannabinoid

The endocannabinoid system (ECS), a conserved physiological system emerged as a novel pharmacological target for its significant role and potential therapeutic benefits ranging from neurological diseases to cancer. Among both, CB1 and CB2R types, CB2R have received attention for its pharmacological effects as antioxidant, anti-inflammatory, immunomodulatory and antiapoptotic that can be achieved without causing psychotropic adverse effects through CB1R. The ligands activate CB2R are of endogenous, synthetic and plant origin. In recent years, β-caryophyllene (BCP), a natural bicyclic sesquiterpene in cannabis as well as non-cannabis plants, has received attention due to its selective agonist property on CB2R. BCP has been well studied in a variety of pathological conditions mediating CB2R selective agonist property. The focus of the present manuscript is to represent the CB2R selective agonist mediated pharmacological mechanisms and therapeutic potential of BCP. The present narrative review summarizes insights into the CB2R-selective pharmacological properties and therapeutic potential of BCP such as cardioprotective, hepatoprotective, neuroprotective, nephroprotective, gastroprotective, chemopreventive, antioxidant, anti-inflammatory, and immunomodulator. The available evidences suggest that BCP, can be an important candidate of plant origin endowed with CB2R selective properties that may provide a pharmacological rationale for its pharmacotherapeutic application and pharmaceutical development like a drug. Additionally, given the wide availability in edible plants and dietary use, with safety, and no toxicity, BCP can be promoted as a nutraceutical and functional food for general health and well-being. Further, studies are needed to explore pharmacological and pharmaceutical opportunities for therapeutic and preventive applications of use of BCP in human diseases.

β-Caryophyllene, A Natural Dietary CB2 Receptor Selective Cannabinoid can be a Candidate to Target the Trinity of Infection, Immunity, and Inflammation in COVID-19

Coronavirus disease (COVID-19), caused by novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is an ongoing pandemic and presents a public health emergency. It has affected millions of people and continues to affect more, despite tremendous social preventive measures. Identifying candidate drugs for the prevention and treatment of COVID-19 is crucial. The pathogenesis and the complications with advanced infection mainly involve an immune-inflammatory cascade. Therefore, therapeutic strategy relies on suppressing infectivity and inflammation, along with immune modulation. One of the most promising therapeutic targets for the modulation of immune-inflammatory responses is the endocannabinoid system, particularly the activation of cannabinoid type 2 receptors (CB2R), a G-protein coupled receptor which mediates the anti-inflammatory properties by modulating numerous signaling pathways. To pharmacologically activate the CB2 receptors, a naturally occurring cannabinoid ligand, beta-caryophyllene (BCP), received attention due to its potent anti-inflammatory, antiviral, and immunomodulatory properties. BCP is recognized as a full selective functional agonist on CB2 receptors and produces therapeutic effects by activating CB2 and the nuclear receptors, peroxisome proliferator-activated receptors (PPARs). BCP is regarded as the first dietary cannabinoid with abundant presence across cannabis and non-cannabis plants, including spices and other edible plants. BCP showed tissue protective properties and favorably modulates numerous signaling pathways and inhibits inflammatory mediators, including cytokines, chemokines, adhesion molecules, prostanoids, and eicosanoids. Based on its pharmacological properties, molecular mechanisms, and the therapeutic potential of BCP as an immunomodulator, anti-inflammatory, organ-protective, and antiviral, we hypothesize that BCP could be a promising therapeutic and/or preventive candidate to target the triad of infection, immunity, and inflammation in COVID-19. In line with numerous studies that proposed the potential of cannabinoids in COVID-19, BCP may be a novel candidate compound for pharmaceutical and nutraceutical development due to its unique functional receptor selectivity, wide availability and accessibility, dietary bioavailability, nonpsychoactivity, and negligible toxicity along with druggable properties, including favorable pharmacokinetic and physicochemical properties. Based on reasonable pharmacological mechanisms and therapeutic properties, we speculate that BCP has potential to be investigated against COVID-19 and will inspire further preclinical and clinical studies.

Characterization of pepcan-23 as pro-peptide of RVD-hemopressin (pepcan-12) and stability of hemopressins in mice

Hemopressins ((x)-PVNFKLLSH) or peptide endocannabinoids (pepcans) can bind to cannabinoid receptors. RVD-hemopressin (pepcan-12) was shown to act as endogenous allosteric modulator of cannabinoid receptors, with opposite effects on CB1 and CB2, respectively. Moreover, the N-terminally elongated pepcan-23 was detected in different tissues and was postulated to be the pro-peptide of RVD-hemopressin. Currently, data about the pharmacokinetics, tissue distribution and stability of hemopressin-type peptides are lacking. Here we investigated the secondary structure and physiological role of pepcan-23 as precursor of RVD-hemopressin. We assessed the metabolic stability of these peptides, including hemopressin. Using LC-ESI-MS/MS, pepcan-23 was measured in mouse tissues and human whole blood (~50 pmol/mL) and in plasma was the most stable endogenous peptide containing the hemopressin sequence. Using peptide spiked human whole blood, mouse adrenal gland and liver homogenates demonstrate that pepcan-23 acts as endogenous pro-peptide of RVD-hemopressin. Furthermore, administered pepcan-23 converted to RVD-hemopressin in mice. In circular dichroism spectroscopy, pepcan-23 showed a helix-unordered-helix structure and efficiently formed complexes with divalent metal ions, in particular Cu(II) and Ni(II). Hemopressin and RVD-hemopressin were not bioavailable to the brain and showed poor stability in plasma, in agreement with their overall poor biodistribution. Acute hemopressin administration (100 mg/kg) did not modulate endogenous RVD-hemopressin/pepcan-23 levels or influence the endocannabinoid lipidome but increased 1-stearoyl-2-arachidonoyl-sn-glycerol. Overall, we show that pepcan-23 is a biological pro-peptide of RVD-hemopressin and divalent metal ions may regulate this process. Given the lack of metabolic stability of hemopressins, administration of pepcan-23 as pro-peptide may be suitable in pharmacological experiments as it is converted to RVD-hemopressin in vivo.

Polygonum minus essential oil modulates cisplatin-induced hepatotoxicity through inflammatory and apoptotic pathways

Oxidative stress, inflammation and apoptosis are thought as primary mediators of cisplatin-induced hepatotoxicity. The objective of this study was to determine the protective effect of Polygonum minus essential oil in cisplatin-induced hepatotoxicity. A total of forty-two male rats were randomly divided into seven groups: control, cisplatin, β-caryophyllene 150 mg/kg (BCP), PmEO 100 mg/kg + cisplatin (PmEO100CP), PmEO 200 mg/kg + cisplatin (PmEO200CP), PmEO 400 mg/kg + cisplatin (PmEO400CP) and PmEO 400 mg/kg (PmEO400). Rats in the BCP, PmEO100CP, PmEO200CP, PmEO400CP and PmEO400 group received respective treatment orally for 14 consecutive days prior to cisplatin injection. All animals except for those in the control group and PmEO400 were administered with a single dose of cisplatin (10 mg/kg) intraperitoneally on day 15 and all animals were sacrificed on day 18. PmEO100CP pretreatment protected against cisplatin-induced hepatotoxicity by decreasing CYP2E1 and indicators of oxidative stress including malondialdehyde, 8-OHdG and protein carbonyl which was accompanied by increased antioxidant status (glutathione, glutathione peroxidase, superoxide dismutase and catalase) as compared to cisplatin group. PmEO100CP pretreatment also modulated changes in liver inflammatory markers (TNF-α, IL-1α, IL-1β, IL-6 and IL-10). PmEO100CP administration also notably reduced cisplatin-induced apoptosis significantly as compared to cisplatin group. In conclusion, our results suggested that P. minus essential oil at a dose of 100 mg/kg may protect against cisplatin-induced hepatotoxicity possibly via inhibition of oxidative stress, inflammation and apoptosis.

Targeting Cannabinoid Receptors: Current Status and Prospects of Natural Products

Cannabinoid receptors (CB1 and CB2), as part of the endocannabinoid system, play a critical role in numerous human physiological and pathological conditions. Thus, considerable efforts have been made to develop ligands for CB1 and CB2, resulting in hundreds of phyto- and synthetic cannabinoids which have shown varying affinities relevant for the treatment of various diseases. However, only a few of these ligands are clinically used. Recently, more detailed structural information for cannabinoid receptors was revealed thanks to the powerfulness of cryo-electron microscopy, which now can accelerate structure-based drug discovery. At the same time, novel peptide-type cannabinoids from animal sources have arrived at the scene, with their potential in vivo therapeutic effects in relation to cannabinoid receptors. From a natural products perspective, it is expected that more novel cannabinoids will be discovered and forecasted as promising drug leads from diverse natural sources and species, such as animal venoms which constitute a true pharmacopeia of toxins modulating diverse targets, including voltage- and ligand-gated ion channels, G protein-coupled receptors such as CB1 and CB2, with astonishing affinity and selectivity. Therefore, it is believed that discovering novel cannabinoids starting from studying the biodiversity of the species living on planet earth is an uncharted territory.

A Systematic Review of Essential Oils and the Endocannabinoid System: A Connection Worthy of Further Exploration

Aromatic compounds have a long history of use as medicines in most recorded cultures. An increasing interest in these therapeutic volatile molecules in both scientific and lay communities has led to the advancement of essential oils as phytomedicines. Recent discoveries suggest essential oils augment the endocannabinoid system in a positive manner to mitigate various pathologies. However, the exact mechanisms whereby essential oils influence endocannabinoid system activity are not fully known, these studies provide a glimpse into their involvement and warrant further evaluation. Additional study of the interaction between essential oils and the endocannabinoid system may lead to promising phytomedicines for the treatment of diseases and conditions involving dysregulation or activation of the endocannabinoid system.

Neutrophil Chemotaxis and NETosis in Murine Chronic Liver Injury via Cannabinoid Receptor 1/ Gαi/o/ ROS/ p38 MAPK Signaling Pathway

Neutrophils play an essential role in the control of inflammatory diseases. However, whether cannabinoid receptors (CBs) play a role in neutrophil chemotaxis and NETosis in sterile liver inflammation remains unknown. The expression of marker genes on neutrophils was characterized by FACS, immunofluorescence, qRT-PCR, and Western blot. The amount of neutrophils was significantly elevated from 7 days and reached the peak at 2 weeks in carbon tetrachloride (CCl₄)-treated mouse liver. The mRNA expression of neutrophil marker Ly6G had positive correlation with CB1 and CB2 expression in injured liver. In vitro CBs were abundantly expressed in isolated neutrophils and CB1 agonist ACEA promoted the chemotaxis and cytoskeletal remodeling, which can be suppressed by CB1 antagonist AM281. Moreover, ACEA induced NETosis, myeloperoxidase release from lysosome and ROS burst, indicating neutrophil activation, via Gα_i/o. Conversely, CB2 agonist JWH133 had no effect on neutrophil function. ROS and p38 MAPK signaling pathways were involved in CB1-mediated neutrophil function, and ROS was upstream of p38 MAPK. CB1 blockade in vivo significantly attenuated neutrophil infiltration and liver inflammation in CCl₄-treated mice. Taken together, CB1 mediates neutrophil chemotaxis and NETosis via Gα_i/o/ROS/p38 MAPK signaling pathway in liver inflammation, which represents an effective therapeutic strategy for liver diseases.

Signaling molecules targeting cannabinoid receptors: Hemopressin and related peptides

Cannabinoid receptors (CBRs) are part of the endocannabinoid system, which is involved in various physiological processes such as nociception, inflammation, appetite, stress, and emotion regulation. Many studies have linked the endocannabinoid system to neuroinflammatory and neurodegenerative disorders such as Parkinson's disease, Huntington's chorea, Alzheimer's disease, and multiple sclerosis. Hemopressin [Hp; a fragment of the hemoglobin α1 chain (95-103 amino acids)] and related peptides [VD-Hpα and RVD-Hpα] are peptides that bind to CBRs. Hp acts as an inverse agonist to CB₁ receptor (CB₁R), VD-Hpα acts as an agonist to CB₁R, and RVD-Hpα acts as a negative allosteric modulator of CB₁R and a positive allosteric modulator of CB₂R. Because of the critical roles of CBRs in numerous physiological processes, it is appealing to use Hp and related peptides for therapeutic purposes. This review discusses their discovery, structure, metabolism, brain exposure, self-assembly characteristics, pharmacological characterization, and pharmacological activities.

Beta-caryophyllene enhances wound healing through multiple routes

Beta-caryophyllene is an odoriferous bicyclic sesquiterpene found in various herbs and spices. Recently, it was found that beta-caryophyllene is a ligand of the cannabinoid receptor 2 (CB2). Activation of CB2 will decrease pain, a major signal for inflammatory responses. We hypothesized that beta-caryophyllene can affect wound healing by decreasing inflammation. Here we show that cutaneous wounds of mice treated with beta-caryophyllene had enhanced re-epithelialization. The treated tissue showed increased cell proliferation and cells treated with beta-caryophyllene showed enhanced cell migration, suggesting that the higher re-epithelialization is due to enhanced cell proliferation and cell migration. The treated tissues also had up-regulated gene expression for hair follicle bulge stem cells. Olfactory receptors were not involved in the enhanced wound healing. Transient Receptor Potential channel genes were up-regulated in the injured skin exposed to beta-caryophyllene. Interestingly, there were sex differences in the impact of beta- caryophyllene as only the injured skin of female mice had enhanced re-epithelialization after exposure to beta-caryophyllene. Our study suggests that chemical compounds included in essential oils have the capability to improve wound healing, an effect generated by synergetic impacts of multiple pathways.

Intracellular Peptides in Cell Biology and Pharmacology

Intracellular peptides are produced by proteasomes following degradation of nuclear, cytosolic, and mitochondrial proteins, and can be further processed by additional peptidases generating a larger pool of peptides within cells. Thousands of intracellular peptides have been sequenced in plants, yeast, zebrafish, rodents, and in human cells and tissues. Relative levels of intracellular peptides undergo changes in human diseases and also when cells are stimulated, corroborating their biological function. However, only a few intracellular peptides have been pharmacologically characterized and their biological significance and mechanism of action remains elusive. Here, some historical and general aspects on intracellular peptides' biology and pharmacology are presented. Hemopressin and Pep19 are examples of intracellular peptides pharmacologically characterized as inverse agonists to cannabinoid type 1 G-protein coupled receptors (CB1R), and hemopressin fragment NFKF is shown herein to attenuate the symptoms of pilocarpine-induced epileptic seizures. Intracellular peptides EL28 (derived from proteasome 26S protease regulatory subunit 4; Rpt2), PepH (derived from Histone H2B type 1-H), and Pep5 (derived from G1/S-specific cyclin D2) are examples of peptides that function intracellularly. Intracellular peptides are suggested as biological functional molecules, and are also promising prototypes for new drug development.

Celastrol alleviates renal fibrosis by upregulating cannabinoid receptor 2 expression

Renal fibrosis is the final manifestation of various chronic kidney diseases, and no effective therapy is available to prevent or reverse it. Celastrol, a triterpene that derived from traditional Chinese medicine, is a known potent anti-fibrotic agent. However, the underlying mechanisms of action of celastrol on renal fibrosis remain unknown. In this study, we found that celastrol treatment remarkably attenuated unilateral ureteral obstruction (UUO)-induced mouse renal fibrosis. This was evidenced by the significant reduction in tubular injury; collagen deposition; accumulation of fibronectin, collagen I, and α-smooth muscle actin; and the expression levels of pro-fibrotic factors Vim, Cola1, and TGF-β1 mRNA, as well as inflammatory responses. Celastrol showed similar effects in a folic acid-induced mouse renal fibrosis model. Furthermore, celastrol potentiated the expression of the anti-fibrotic factor cannabinoid receptor 2 (CB2R) in established mouse fibrotic kidney tissues and transforming growth factor β1 (TGF-β1)-stimulated human kidney 2 (HK-2) cells. In addition, the CB2R antagonist (SR144528) abolished celastrol-mediated beneficial effects on renal fibrosis. Moreover, UUO- or TGF-β1-induced activation of the pro-fibrotic factor SMAD family member 3 (Smad3) was markedly inhibited by celastrol. Inhibition of Smad3 activation by an inhibitor (SIS3) markedly reduced TGF-β1-induced downregulation of CB2R expression. In conclusion, our study provides the first direct evidence that celastrol significantly alleviated renal fibrosis, by contributing to the upregulation of CB2R expression through inhibiting Smad3 signaling pathway activation. Therefore, celastrol could be a potential drug for treating patients with renal fibrosis.

Increased expression of type 1 cannabinoid (CB1) receptor among patients with rotator cuff lesions and shoulder stiffness

BACKGROUND

Shoulder stiffness is a disease manifested by pain, limited range of motion, and functional disability. The inflammatory and fibrosis processes play a substantial role in the pathogenesis of shoulder stiffness. The CB1 receptor has been recognized to mediate the processes of pathologic fibrosis. This study investigated the role of the CB1 pathway in pathogenesis of rotator cuff lesions with shoulder stiffness.

METHODS

All of the patients undergoing repair surgery for rotator cuff lesions were recruited and subcategorized into subjects with and without shoulder stiffness. Reverse transcription-polymerase chain reaction assay was used to evaluate the expression level of CB1 and interleukin 1β (IL-1β) in the subacromial bursae, and enzyme-linked immunosorbent assay was used to measure the concentration of CB1 and IL-1β in the subacromial fluid. Tenocytes treated with CB1 agonists and antagonists were also studied for the relationship of CB1 and the inflammatory cytokine IL-1β.

RESULTS

The patients with shoulder stiffness had higher messenger RNA (mRNA) expression (P = .040) and immunohistochemistry staining (P < .001) of CB1 in the subacromial bursa and higher CB1 concentration in the subacromial fluid (P = .008). Tenocytes treated with the CB1 agonist WIN 55,212-2 and antagonist AM251 showed increased expression of IL-1β mRNA (P = .049) and suppressed expression of IL-1β mRNA (P = .001), respectively.

DISCUSSION

The CB1 pathway is involved in the pathogenesis of shoulder stiffness. It may be a promising target for the treatment of rotator cuff lesions with shoulder stiffness.

Drugs and Targets in Fibrosis

Fibrosis contributes to the development of many diseases and many target molecules are involved in fibrosis. Currently, the majority of fibrosis treatment strategies are limited to specific diseases or organs. However, accumulating evidence demonstrates great similarities among fibroproliferative diseases, and more and more drugs are proved to be effective anti-fibrotic therapies across different diseases and organs. Here we comprehensively review the current knowledge on the pathological mechanisms of fibrosis, and divide factors mediating fibrosis progression into extracellular and intracellular groups. Furthermore, we systematically summarize both single and multiple component drugs that target fibrosis. Future directions of fibrosis drug discovery are also proposed.

Human Chorionic Plate-Derived Mesenchymal Stem Cells Restore Hepatic Lipid Metabolism in a Rat Model of Bile Duct Ligation

In cholestatic liver diseases, impaired bile excretion disrupts lipid homeostasis. We investigated changes of lipid metabolism, including mitochondrial β-oxidation, in a rat model of bile duct ligation (BDL) in which chorionic plate-derived mesenchymal stem cells (CP-MSCs) were transplanted. Serum cholesterol level, which was elevated after BDL, was significantly decreased following CP-MSC transplantation. The expression levels of genes involved in intracellular lipid uptake, including long-chain fatty acyl-CoA synthetases and fatty acid transport proteins, were decreased in rats after BDL; however, they were not significantly changed by subsequent CP-MSC transplantation. Carnitine palmitoyltransferase 1A (CPT1A), a rate-limiting enzyme in mitochondrial β-oxidation, was upregulated after BDL and then was downregulated after CP-MSC transplantation. CPT1A expression was changed via microRNA-33—a posttranscriptional regulator of CPT1A—in a peroxisome proliferator-activated receptor α-independent manner. Cellular adenosine triphosphate production—an indicator of mitochondrial function—was reduced after BDL and was restored by CP-MSC transplantation. Expression levels of heme oxygenases also were significantly affected following BDL and CP-MSC transplantation. Lipid metabolism is altered in response to chronic cholestatic liver injury and can be restored by CP-MSC transplantation. Our study findings support the therapeutic potential of CP-MSCs in cholestatic liver diseases and help in understanding the fundamental mechanisms by which CP-MSCs affect energy metabolism.

Adipose-derived mesenchymal stem cells slow disease progression of acute-on-chronic liver failure

A serious complication of chronic hepatic insufficiency is acute-on-chronic liver failure, a recognized syndrome characterized by acute decompensation of cirrhosis and organ/system failure. We investigated the use of adipose-derived mesenchymal stem cells (AD-MSCs) in an experimental model of acute-on-chronic liver failure, developed by microsurgical extrahepatic cholestasis in rats. Rats undergoing microsurgical extrahepatic cholestasis were treated by intraparenchymal liver injection of human or rat AD-MSCs, undifferentiated or previously differentiated in vitro toward the hepatocyte lineage. The groups treated with rat AD-MSCs showed less ascites, lower hepato- and splenomegaly, less testicular atrophy, and an improvement in serum biochemical hepatic parameters. There was also an improvement in histological liver changes, in which the area of fibrosis and bile duct proliferation were significantly decreased in the group treated with predifferentiated rat AD-MSCs. In conclusion, an isograft of hepatocyte-predifferentiated AD-MSCs injected intraparenchymally 2 weeks after microsurgery in extrahepatic cholestatic rats prevents secondary complications of acute-on-chronic hepatic failure. These data support the potential use of autologous AD-MSCs in the treatment of human cholestasis, and specifically of newborn biliary atresia, which could be beneficial for patients awaiting transplant.

β-Caryophyllene protects against alcoholic steatohepatitis by attenuating inflammation and metabolic dysregulation in mice

BACKGROUND AND AIMS

β-Caryophyllene (BCP) is a plant-derived FDA approved food additive with anti-inflammatory properties. Some of its beneficial effects in vivo are reported to involve activation of cannabinoid CB₂ receptors that are predominantly expressed in immune cells. Here, we evaluated the translational potential of BCP using a well-established model of chronic and binge alcohol-induced liver injury.

METHODS

In this study, we investigated the effects of BCP on liver injury induced by chronic plus binge alcohol feeding in mice in vivo by using biochemical assays, real-time PCR and histology analyses. Serum and hepatic BCP levels were also determined by GC/MS.

RESULTS

Chronic treatment with BCP alleviated the chronic and binge alcohol-induced liver injury and inflammation by attenuating the pro-inflammatory phenotypic `M1` switch of Kupffer cells and by decreasing the expression of vascular adhesion molecules intercellular adhesion molecule 1, E-Selectin and P-Selectin, as well as the neutrophil infiltration. It also beneficially influenced hepatic metabolic dysregulation (steatosis, protein hyperacetylation and PPAR-α signalling). These protective effects of BCP against alcohol-induced liver injury were attenuated in CB₂ receptor knockout mice, indicating that the beneficial effects of this natural product in liver injury involve activation of these receptors. Following acute or chronic administration, BCP was detectable both in the serum and liver tissue homogenates but not in the brain.

CONCLUSIONS

Given the safety of BCP in humans, this food additive has a high translational potential in treating or preventing hepatic injury associated with oxidative stress, inflammation and steatosis.

LINKED ARTICLES

This article is part of a themed section on Inventing New Therapies Without Reinventing the Wheel: The Power of Drug Repurposing. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.2/issuetoc.

Decreased C-reactive protein induces abnormal vascular structure in a rat model of liver dysfunction induced by bile duct ligation

Background/Aims

Chronic liver disease leads to liver fibrosis, and although the liver does have a certain regenerative capacity, this disease is associated with dysfunction of the liver vessels. C-reactive protein (CRP) is produced in the liver and circulated from there for metabolism. CRP was recently shown to inhibit angiogenesis by inducing endothelial cell dysfunction. The objective of this study was to determine the effect of CRP levels on angiogenesis in a rat model of liver dysfunction induced by bile duct ligation (BDL).

Methods

The diameter of the hepatic vein was analyzed in rat liver tissues using hematoxylin and eosin (H&E) staining. The expression levels of angiogenic factors, albumin, and CRP were analyzed by real-time PCR and Western blotting. A tube formation assay was performed to confirm the effect of CRP on angiogenesis in human umbilical vein endothelial cells (HUVECs) treated with lithocholic acid (LCA) and siRNA-CRP.

Results

The diameter of the hepatic portal vein increased significantly with the progression of cirrhosis. The expression levels of angiogenic factors were increased in the cirrhotic liver. In contrast, the expression levels of albumin and CRP were significantly lower in the liver tissue obtained from the BDL rat model than in the normal liver. The CRP level was correlated with the expression of albumin in hepatocytes treated with LCA and siRNA-CRP. Tube formation was significantly decreased in HUVECs when they were treated with LCA or a combination of LCA and siRNA-CRP.

Conclusion

CRP seems to be involved in the abnormal formation of vessels in hepatic disease, and so it could be a useful diagnostic marker for hepatic disease.

Hybrid inhibitor of peripheral cannabinoid-1 receptors and inducible nitric oxide synthase mitigates liver fibrosis

Liver fibrosis, a consequence of chronic liver injury and a way station to cirrhosis and hepatocellular carcinoma, lacks effective treatment. Endocannabinoids acting via cannabinoid-1 receptors (CB₁R) induce profibrotic gene expression and promote pathologies that predispose to liver fibrosis. CB₁R antagonists produce opposite effects, but their therapeutic development was halted due to neuropsychiatric side effects. Inducible nitric oxide synthase (iNOS) also promotes liver fibrosis and its underlying pathologies, but iNOS inhibitors tested to date showed limited therapeutic efficacy in inflammatory diseases. Here, we introduce a peripherally restricted, orally bioavailable CB₁R antagonist, which accumulates in liver to release an iNOS inhibitory leaving group. In mouse models of fibrosis induced by CCl₄ or bile duct ligation, the hybrid CB₁R/iNOS antagonist surpassed the antifibrotic efficacy of the CB₁R antagonist rimonabant or the iNOS inhibitor 1400W, without inducing anxiety-like behaviors or CB₁R occupancy in the CNS. The hybrid inhibitor also targeted CB₁R-independent, iNOS-mediated profibrotic pathways, including increased PDGF, Nlrp3/Asc3, and integrin αvβ6 signaling, as judged by its ability to inhibit these pathways in cnr1^-/- but not in nos2^-/- mice. Additionally, it was able to slow fibrosis progression and to attenuate established fibrosis. Thus, dual-target peripheral CB₁R/iNOS antagonists have therapeutic potential in liver fibrosis.

Pharmacological activation of cannabinoid 2 receptor attenuates inflammation, fibrogenesis, and promotes re-epithelialization during skin wound healing

Previous studies showed that cannabinoid 2 (CB2) receptor is expressed in multiple effector cells during skin wound healing. Meanwhile, its functional involvement in inflammation, fibrosis, and cell proliferation in other organs and skin diseases implied CB2 receptor might also regulate skin wound healing. To verify this hypothesis, mice excisional wounds were created and treated with highly selective CB2 receptor agonist GP1a (1-(2,4-dichlorophenyl)-6-methyl- N-piperidin-1-yl-4H-indeno[1,2-c]pyrazole-3-carboxamide) and antagonist AM630 ([6-iodo-2- methyl-1-(2-morpholin-4-ylethyl)indol-3-yl]-(4-methoxyphenyl)methanone) respectively. The inflammatory infiltration, cytokine expression, fibrogenesis, and wound re-epithelialization were analyzed. After CB2 receptor activation, neutrophil and macrophage infiltrations were reduced, and expressions of monocyte chemotactic protein (MCP)-1, stromal cell-derived factor (SDF)-1, Interleukin (IL)-6, IL-1β, tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-β1 and vascular endothelial growth factor (VEGF)-A were decreased. Keratinocyte proliferation and migration were enhanced. Wound re-epithelialization was accelerated. Fibroblast accumulation and fibroblast-to-myofibroblast transformation were attenuated, and expression of pro-collagen I was decreased. Furthermore, HaCaT cells in vitro were treated with GP1a or AM630, which revealed that CB2 receptor activation promoted keratinocyte migration by inducing the epithelial to mesenchymal transition. These results, taken together, indicate that activating CB2 receptor could ameliorate wound healing by reducing inflammation, accelerating re-epithelialization, and attenuating scar formation. Thus, CB2 receptor agonist might be a novel perspective for skin wound therapy.

Cannabinoid CB₂ receptors are involved in the regulation of fibrogenesis during skin wound repair in mice

Studies have shown that cannabinoid CB2 receptors are involved in wound repair, however, its physiological roles in fibrogenesis remain to be elucidated. In the present study, the capacity of cannabinoid CB2 receptors in the regulation of skin fibrogenesis during skin wound healing was investigated. To assess the function of cannabinoid CB2 receptors, skin excisional BALB/c mice were treated with either the cannabinoid CB2 receptor selective agonist, GP1a, or antagonist, AM630. Skin fibrosis was assessed by histological analysis and profibrotic cytokines were determined by immunohistochemistry, immunofluorescence staining, reverse transcription‑quantitative polymerase chain reaction and immunoblotting in these animals. GP1a decreased collagen deposition, reduced the levels of transforming growth factor (TGF)‑β1, TGF‑β receptor I (TβRI) and phosphorylated small mothers against decapentaplegic homolog 3 (P‑Smad3), but elevated the expression of its inhibitor, Smad7. By contrast, AM630 increased collagen deposition and the expression levels of TGF‑β1, TβRI and P‑Smad3. These results indicated that cannabinoid CB2 receptors modulate fibrogenesis and the TGF‑β/Smad profibrotic signaling pathway during skin wound repair in the mouse.

Cannabinoid receptor 2 and several digestive system diseases

The endocannabinoid system is made up of endocannabinoid, cannabinoid receptor type 1 (CB1) and cannabinoid receptor type 2 (CB2). A multitude of physiological effects and putative pathophysiological roles have been proposed for the endogenous cannabinoid system in the gastrointestinal tract, liver, pancreas and tumors. This paper aims to review the endocannabinoid system and the relations of CB2 with irritable bowel syndrome, inflammatory bowel disease, pancreatitis, hepatic disease and digestive system tumors.

Small Molecules from Nature Targeting G-Protein Coupled Cannabinoid Receptors: Potential Leads for Drug Discovery and Development

The cannabinoid molecules are derived from Cannabis sativa plant which acts on the cannabinoid receptors types 1 and 2 (CB1 and CB2) which have been explored as potential therapeutic targets for drug discovery and development. Currently, there are numerous cannabinoid based synthetic drugs used in clinical practice like the popular ones such as nabilone, dronabinol, and Δ(9)-tetrahydrocannabinol mediates its action through CB1/CB2 receptors. However, these synthetic based Cannabis derived compounds are known to exert adverse psychiatric effect and have also been exploited for drug abuse. This encourages us to find out an alternative and safe drug with the least psychiatric adverse effects. In recent years, many phytocannabinoids have been isolated from plants other than Cannabis. Several studies have shown that these phytocannabinoids show affinity, potency, selectivity, and efficacy towards cannabinoid receptors and inhibit endocannabinoid metabolizing enzymes, thus reducing hyperactivity of endocannabinoid systems. Also, these naturally derived molecules possess the least adverse effects opposed to the synthetically derived cannabinoids. Therefore, the plant based cannabinoid molecules proved to be promising and emerging therapeutic alternative. The present review provides an overview of therapeutic potential of ligands and plants modulating cannabinoid receptors that may be of interest to pharmaceutical industry in search of new and safer drug discovery and development for future therapeutics.

Non-coding RNA-mediated epigenetic regulation of liver fibrosis

Hepatic stellate cells (HSC) activation plays a key role in liver fibrosis. Numerous studies have indicated that non-coding RNAs (ncRNAs) control liver fibrosis and fibroblasts proliferation. Greater knowledge of the role of the ncRNAs-mediated epigenetic mechanism in liver fibrosis could improve understanding of the liver fibrosis pathogenesis. The aim of this review is to describe the present knowledge about the ncRNAs significantly participating in liver fibrosis and HSC activation, and look ahead on new perspectives of ncRNAs-mediated epigenetic mechanism research. Moreover, we will discuss examples of non-coding RNAs that interact with histone modification or DNA methylation to regulate gene expression in liver fibrosis. Diverse classes of ncRNAs, ranging from microRNAs (miRs) to long non-coding RNAs (LncRNAs), have emerged as key regulators of several important aspects of function, including cell proliferation, activation, etc. In addition, recent advances suggest the important role of ncRNAs transcripts in epigenetic gene regulation. Targeting the miRs and LncRNAs can be a promising direction in liver fibrosis treatment. We discuss new perspectives of miRs and LncRNAs in liver fibrosis and HSC activation, mainly including interaction with histone modification or DNA methylation to regulate gene expression. These epigenetic mechanisms form powerful ncRNAs surveillance systems that may represent new targets for liver fibrosis therapeutic intervention.

Bisdemethoxycurcumin Induces apoptosis in activated hepatic stellate cells via cannabinoid receptor 2

Activated Hepatic Stellate Cells (HSCs), major fibrogenic cells in the liver, undergo apoptosis when liver injuries cease, which may contribute to the resolution of fibrosis. Bisdemethoxycurcumin (BDMC) is a natural derivative of curcumin with anti-inflammatory and anti-cancer activities. The therapeutic potential of BDMC in hepatic fibrosis has not been studied thus far in the context of the apoptosis in activated HSCs. In the current study, we compared the activities of BDMC and curcumin in the HSC-T6 cell line and demonstrated that BDMC relatively induced a potent apoptosis. BDMC-induced apoptosis was mediated by a combinatory inhibition of cytoprotective proteins, such as Bcl₂ and heme oxygenase-1 and increased generation of reactive oxygen species. Intriguingly, BDMC-induced apoptosis was reversed with co-treatment of sr144528, a cannabinoid receptor (CBR) 2 antagonist, which was confirmed with genetic downregulation of the receptor using siCBR2. Additionally, incubation with BDMC increased the formation of death-induced signaling complex in HSC-T6 cells. Treatment with BDMC significantly diminished total intracellular ATP levels and upregulated ATP inhibitory factor-1. Collectively, the results demonstrate that BDMC induces apoptosis in activated HSCs, but not in hepatocytes, by impairing cellular energetics and causing a downregulation of cytoprotective proteins, likely through a mechanism that involves CBR2.