Overactive cannabinoid 1 receptor in podocytes drives type 2 diabetic nephropathy

Therapeutic Effect of Lebanese Cannabis Oil Extract in the Management of Sodium Orthovanadate-Induced Nephrotoxicity in Rats

Sodium orthovanadate is a non-selective protein tyrosine phosphatase inhibitor that can cause several types of kidney injury, including glomerulosclerosis, inflammation, and tubular damage. Cannabis is widely known for its medicinal use, and several studies have demonstrated its anti-diabetic and anti-inflammatory properties. The current study investigated the therapeutic effect of Lebanese cannabis oil extract (COE) against sodium orthovanadate-induced nephrotoxicity both in vitro and in vivo. Sprague Dawley male rats were intraperitoneally injected with 10 mg/kg sodium orthovanadate for 10 days followed by 5 mg/kg; 10 mg/kg; or 20 mg/kg intraperitoneal injection of cannabis oil extract, starting on day 4 until day 10. The body weight of the rats was monitored during the study, and clinical parameters, including serum urea, creatinine, and electrolytes, as well as kidney and heart pathology, were measured. Conditionally immortalized cultured rat podocytes were exposed to either sodium orthovanadate or selective phosphatase inhibitors, including DUSPi (DUSP1/6 inhibitor) and SF1670 (PTEN inhibitor), in the presence or absence of cannabis oil extract. MTS and an in vitro scratch assay were used to assess podocyte cell viability and migration, respectively. Western blot analysis was used to evaluate the phosphorylation levels of AKT and p38 MAPK. Rats injected with sodium orthovanadate displayed a marked reduction in body weight and an increase in serum creatinine and urea in comparison to the control non-treated group. All doses of COE caused a significant decrease in serum urea, with a significant decrease in serum creatinine observed at a dose of 20 mg/kg. Moreover, the COE treatment of rats injected with orthovanadate (20 mg/kg) showed a marked reduction in renal vascular dilatation, scattered foci of acute tubular necrosis, and numerous mitoses in tubular cells compared to the sodium orthovanadate-treated group. The cell viability assay revealed that COE reversed cytotoxicity induced by sodium orthovanadate and specific phosphatase inhibitors (DUSPi and SF1670) in rat podocytes. The in vitro scratch assay showed that COE partially restored the migratory capacity of podocytes incubated with DUSPi and SF1670. Time-course and dose-dependent experiments showed that COE (1 μg/mL) induced a significant increase in phospho-(S473)-AKT, along with a decrease in phospho (T180 + Y182) P38 levels. The current results demonstrated that Lebanese cannabis oil possesses important kidney protective effects against sodium orthovanadate-induced renal injury.

Maladaptive Peripheral Ketogenesis in Schwann Cells Mediated by CB1R Contributes to Diabetic Neuropathy

Diabetic peripheral neuropathy (DPN) is the most common complication of diabetes. Although studies have previously investigated metabolic disruptions in the peripheral nervous system (PNS), the exact metabolic mechanisms underlying DPN remain largely unknown. Herein, a specific form of metabolic remodeling involving aberrant ketogenesis within Schwann cells (SCs) in streptozotocin (STZ)-induced type I diabetes mellitus is identified. The PNS adapts poorly to such aberrant ketogenesis, resulting in disrupted energy metabolism, mitochondrial damage, and homeostatic decompensation, ultimately contributing to DPN. Additionally, the maladaptive peripheral ketogenesis is highly dependent on the cannabinoid type-1 receptor (CB1R)-Hmgcs2 axis. Silencing CB1R reprogrammed the metabolism of SCs by blocking maladaptive ketogenesis, resulting in rebalanced energy metabolism, reduced histopathological changes, and improved neuropathic symptoms. Moreover, this metabolic reprogramming can be induced pharmacologically using JD5037, a peripheral CB1R blocker. These findings revealed a new metabolic mechanism underlying DPN, and promoted CB1R as a promising therapeutic target for DPN.

Chemical Probes for Investigating the Endocannabinoid System

Cannabis sativa has been used therapeutically since early civilizations, with key cannabinoids Δ9-tetrahydrocannabinol (THC) 3.1 and cannabidiol characterized in the 1960s, leading to the discovery of cannabinoid receptors type 1 (CB1R) and type 2 (CB2R) and the endocannabinoid system (ECS) in the 1990s. The ECS, involving endogenous ligands like 2-arachidonoylglycerol (2-AG) 1.1, anandamide (N-arachidonoylethanolamine (AEA)) 1.2, and various proteins, regulates vital processes such as sleep, appetite, and memory, and holds significant therapeutic potential, especially for neurological disorders. Small molecule-derived pharmacological tools, or chemical probes, target key components of the ECS and are crucial for target validation, mechanistic studies, pathway elucidation, phenotypic screening, and drug discovery. These probes selectively interact with specific proteins or pathways, enabling researchers to modulate target activity and observe biological effects. When they carry an additional reporter group, they are referred to as labeled chemical probes. Developed through medicinal chemistry, structural biology, and high-throughput screening, effective chemical probes must be selective, potent, and depending on their purpose meet additional criteria such as cell permeability and metabolic stability.This chapter describes high-quality labeled and unlabeled chemical probes targeting ECS constituents that have been successfully applied for various research purposes. CB1R and CB2R, class A G protein-coupled receptors, are activated by 2-AG 1.1, AEA 1.2, and THC 3.1, with numerous ligands developed for these receptors. Imaging techniques like single-photon emission computed tomography, positron emission tomography, and fluorescently labeled CB1R and CB2R probes have enhanced CB receptor studies. CB2R activation generally results in immunosuppressive effects, limiting tissue injury. AEA 1.2 is mainly degraded by fatty acid amide hydrolase (FAAH) or N-acylethanolamine acid amidase (NAAA) into ethanolamine and arachidonic acid (AA) 1.3. FAAH inhibitors increase endogenous fatty acid amides, providing analgesic effects without adverse effects. NAAA inhibitors reduce inflammation and pain in animal models. Diacylglycerol lipase (DAGL) is essential for 2-AG 1.1 biosynthesis, while monoacylglycerol lipase (MAGL) degrades 2-AG 1.1 into AA 1.3, thus regulating cannabinoid signaling. Multiple inhibitors targeting FAAH and MAGL have been generated, though NAAA and DAGL probe development lags behind. Similarly, advancements in inhibitors targeting endocannabinoid (eCB) cellular uptake or trafficking proteins like fatty acid-binding proteins have been slower. The endocannabinoidome (eCBome) includes the ECS and related molecules and receptors, offering therapeutic opportunities from non-THC cannabinoids and eCBome mediators. Ongoing research aims to refine chemical tools for ECS and eCBome study, addressing unmet medical needs in central nervous system disorders and beyond.

The effects of cannabinoids on the kidney

Cannabinoids are a class of drugs derived from the Cannabis plant that are widely used for the treatment of various medical conditions and recreational use. Common examples include Δ9-tetrahydrocannabinol (THC), cannabidiol (CBD), spice, and 2-arachidonoylglycerol (2-AG). With more than 100 cannabinoids identified, their influence on the nervous system, role in pain management, and effects due to illicit use have been extensively studied. However, their effects on peripheral organs, such as the kidneys, require further examination. With dramatic rises in use, production, and legalization, it is essential to understand the impact and mechanistic properties of these drugs as they pertain to renal and cardiovascular physiology. The goal of this review is to summarize prior literature on the expression of cannabinoid receptors and how cannabinoids influence renal function. This review first discusses the interaction of the endocannabinoid system (ECS) and renal physiology and pathophysiology. Following, we briefly discuss the role of the ECS in various kidney diseases and the potential therapeutic applications of drugs targeting the cannabinoid system. Lastly, recent studies have identified several detrimental effects of cannabinoids, not only on the kidney but also in contributing to adverse cardiovascular outcomes. Thus, the negative impact of cannabinoids on renal function and the development of various cardiovascular diseases is also discussed.

Myeloid cannabinoid CB1 receptor deletion confers atheroprotection in male mice by reducing macrophage proliferation in a sex-dependent manner

AIMS

Although the cannabinoid CB1 receptor has been implicated in atherosclerosis, its cell-specific effects in this disease are not well understood. To address this, we generated a transgenic mouse model to study the role of myeloid CB1 signalling in atherosclerosis.

METHODS AND RESULTS

Here, we report that male mice with myeloid-specific Cnr1 deficiency on atherogenic background developed smaller lesions and necrotic cores than controls, while only minor genotype differences were observed in females. Male Cnr1-deficient mice showed reduced arterial monocyte recruitment and macrophage proliferation with less inflammatory phenotype. The sex-specific differences in proliferation were dependent on oestrogen receptor (ER)α-oestradiol signalling. Kinase activity profiling identified a CB1-dependent regulation of p53 and cyclin-dependent kinases. Transcriptomic profiling further revealed chromatin modifications, mRNA processing, and mitochondrial respiration among the key processes affected by CB1 signalling, which was supported by metabolic flux assays. Chronic administration of the peripherally restricted CB1 antagonist JD5037 inhibited plaque progression and macrophage proliferation, but only in male mice. Finally, CNR1 expression was detectable in human carotid endarterectomy plaques and inversely correlated with proliferation, oxidative metabolism, and inflammatory markers, suggesting a possible implication of CB1-dependent regulation in human pathophysiology.

CONCLUSION

Impaired macrophage CB1 signalling is atheroprotective by limiting their arterial recruitment, proliferation, and inflammatory reprogramming in male mice. The importance of macrophage CB1 signalling appears to be sex-dependent.

Patent review of cannabinoid receptor type 2 (CB2R) modulators (2016-present)

INTRODUCTION

Cannabinoid receptor type 2 (CB2R), predominantly expressed in immune tissues, is believed to play a crucial role within the body's protective mechanisms. Its modulation holds immense therapeutic promise for addressing a wide spectrum of dysbiotic conditions, including cardiovascular, gastrointestinal, liver, kidney, neurodegenerative, psychiatric, bone, skin, and autoimmune diseases, as well as lung disorders, cancer, and pain management.

AREAS COVERED

This review is an account of patents from 2016 up to 2023 which describes novel CB2R ligands, therapeutic applications, synthesis, as well as formulations of CB2R modulators.

EXPERT OPINION

The patents cover a vast, structurally diverse chemical space. The focus of CB2R ligand development has shifted from unselective dual-cannabinoid receptor type 1 (CB1R) and 2 agonists toward agonists with high selectivity over CB1R, particularly for indications associated with inflammation and tissue injury. Currently, there are at least eight CB2R agonists and one antagonist in active clinical development. A better understanding of the endocannabinoid system (ECS) and in particular of CB2R pharmacology is required to unlock the receptor's full therapeutic potential.

The cannabinoid CB2 receptor positive allosteric modulator EC21a exhibits complicated pharmacology in vitro

Schizophrenia is a complex disease involving the dysregulation of numerous brain circuits and patients exhibit positive symptoms (hallucinations, delusions), negative symptoms (anhedonia), and cognitive impairments. We have shown that the antipsychotic efficacy of positive allosteric modulators (PAMs) of both the M4 muscarinic receptor and metabotropic glutamate receptor 1 (mGlu1) involve the retrograde activation of the presynaptic cannabinoid type-2 (CB2) receptor, indicating that CB2 activation or potentiation could result in a novel therapeutic strategy for schizophrenia. We used two complementary assays, receptor-mediated phosphoinositide hydrolysis and GIRK channel activation, to characterize a CB2 PAM scaffold, represented by the compound EC21a, to explore its potential as a starting point to optimize therapeutics for schizophrenia. These studies revealed that EC21a acts as an allosteric inverse agonist at CB2 in both assays and exhibits a mixed allosteric agonist/negative allosteric modulator profile at CB1 depending upon the assay used for profiling. A series of compounds related to EC21a also functioned as CB2 inverse agonists. Overall, these results suggest that EC21a exhibits complicated and potentially assay-dependent pharmacology, which may impact interpretation of in vivo studies.

Cannabinoid receptor type 1 activation causes a water diuresis by inducing an acute central diabetes insipidus in mice

Cannabis and synthetic cannabinoid consumption are increasing worldwide. Cannabis contains numerous phytocannabinoids that act on the G protein-coupled cannabinoid receptor type 1 (CB1R) and cannabinoid receptor type 2 expressed throughout the body, including the kidney. Essentially every organ, including the kidney, produces endocannabinoids, which are endogenous ligands to these receptors. Cannabinoids acutely increase urine output in rodents and humans, thus potentially influencing total body water and electrolyte homeostasis. As the kidney collecting duct (CD) regulates total body water, acid/base, and electrolyte balance through specific functions of principal cells (PCs) and intercalated cells (ICs), we examined the cell-specific immunolocalization of CB1R in the mouse CD. Antibodies against either the C-terminus or N-terminus of CB1R consistently labeled aquaporin 2 (AQP2)-negative cells in the cortical and medullary CD and thus presumably ICs. Given the well-established role of ICs in urinary acidification, we used a clearance approach in mice that were acid loaded with 280 mM NH4Cl for 7 days and nonacid-loaded mice treated with the cannabinoid receptor agonist WIN55,212-2 (WIN) or a vehicle control. Although WIN had no effect on urinary acidification, these WIN-treated mice had less apical + subapical AQP2 expression in PCs compared with controls and developed acute diabetes insipidus associated with the excretion of large volumes of dilute urine. Mice maximally concentrated their urine when WIN and 1-desamino-8-d-arginine vasopressin [desmopressin (DDAVP)] were coadministered, consistent with central rather than nephrogenic diabetes insipidus. Although ICs express CB1R, the physiological role of CB1R in this cell type remains to be determined.NEW & NOTEWORTHY The CB1R agonist WIN55,212-2 induces central diabetes insipidus in mice. This research integrates existing knowledge regarding the diuretic effects of cannabinoids and the influence of CB1R on vasopressin secretion while adding new mechanistic insights about total body water homeostasis. Our findings provide a deeper understanding about the potential clinical impact of cannabinoids on human physiology and may help identify targets for novel therapeutics to treat water and electrolyte disorders such as hyponatremia and volume overload.

Exploring the Possible Role of Cannabinoids in Managing Post-cardiac Surgery Complications: A Narrative Review of Preclinical Evidence and a Call for Future Research Directions

ABSTRACT

Open-heart surgery with cardiopulmonary bypass often leads to complications including pain, systemic inflammation, and organ damage. Traditionally managed with opioids, these pain relief methods bring potential long-term risks, prompting the exploration of alternative treatments. The legalization of cannabis in various regions has reignited interest in cannabinoids, such as cannabidiol, known for their anti-inflammatory, analgesic, and neuroprotective properties. Historical and ongoing research acknowledges the endocannabinoid system's crucial role in managing physiological processes, suggesting that cannabinoids could offer therapeutic benefits in postsurgical recovery. Specifically, cannabidiol has shown promise in managing pain, moderating immune responses, and mitigating ischemia/reperfusion injury, underscoring its potential in postoperative care. However, the translation of these findings into clinical practice faces challenges, highlighting the need for extensive research to establish effective, safe cannabinoid-based therapies for patients undergoing open-heart surgery. This narrative review advocates for a balanced approach, considering both the therapeutic potential of cannabinoids and the complexities of their integration into clinical settings.

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

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.

The intervention of cannabinoid receptor in chronic and acute kidney disease animal models: a systematic review and meta-analysis

AIM

Cannabinoid receptors are components of the endocannabinoid system that affect various physiological functions. We aim to investigate the effect of cannabinoid receptor modulation on kidney disease.

METHODS

PubMed, Web of Science databases, and EMBASE were searched. Articles selection, data extraction and quality assessment were independently performed by two investigators. The SYRCLE's RoB tool was used to assess the risk of study bias, and pooled SMD using a random-effect model and 95% CIs were calculated. Subgroup analyses were conducted in preselected subgroups, and publication bias was evaluated. We compared the effects of CB1 and CB2 antagonists and/or knockout and agonists and/or genetic regulation on renal function, blood glucose levels, body weight, and pathological damage-related indicators in different models of chronic and acute kidney injury.

RESULTS

The blockade or knockout of CB1 could significantly reduce blood urea nitrogen [SMD,- 1.67 (95% CI - 2.27 to - 1.07)], serum creatinine [SMD, - 1.88 (95% CI - 2.91 to - 0.85)], and albuminuria [SMD, - 1.60 (95% CI - 2.16 to - 1.04)] in renal dysfunction animals compared with the control group. The activation of CB2 group could significantly reduce serum creatinine [SMD, - 0.97 (95% CI - 1.83 to - 0.11)] and albuminuria [SMD, - 2.43 (95% CI - 4.63 to - 0.23)] in renal dysfunction animals compared with the control group.

CONCLUSIONS

The results suggest that targeting cannabinoid receptors, particularly CB1 antagonists and CB2 agonists, can improve kidney function and reduce inflammatory responses, exerting a renal protective effect and maintaining therapeutic potential in various types of kidney disease.

Cannabis use is associated with reduced access to kidney transplantation and an increased risk of acute rejection post-transplant

BACKGROUND

The association between cannabis use and access to waitlisting, transplantation, and post-transplant outcomes remains uncertain.

METHODS

Patients referred for kidney transplant (KT) to the University Health Network from January 1, 2003, to June 30, 2020, and followed until December 31, 2020, were included. Predictors of reported cannabis use were examined using a logistic regression model. The association between cannabis use and time to clearance for KT, undergoing KT, and post-transplant outcomes was evaluated using Cox proportional hazards models.

RESULTS

Among 3734 patients, the prevalence of reported cannabis use was 11.8%. Cannabis use was associated with a lower likelihood of KT clearance (adjusted hazard ratio [aHR] .82 [95% confidence interval (CI): .72, .94]). Once cleared for KT, cannabis use did not predict the subsequent receipt of KT (aHR .92, [95% CI: .79, 1.08]). Among 2091 KT recipients, cannabis use was associated with a higher likelihood of biopsy-proven acute rejection (aHR 1.55, [95% CI: 1.06, 2.27]). The relative hazard of death-censored graft failure was similarly elevated (aHR 1.60 [95% CI: .95, 2.72]). Cannabis use did not predict total graft failure (aHR 1.33 [95% CI: .90, 1.96]), death with graft function (aHR 1.06 [95% CI: .59, 1.89]), or hospital readmission in the first-year post-transplant (aHR 1.26 [95% CI: .95, 1.68]).

CONCLUSIONS

Cannabis users have less access to transplantation and an increased risk of acute rejection, possibly leading to more graft loss. Further studies are warranted to understand possible mechanisms for the increased risk of allograft immune injury among cannabis users.

Multi-omics integration reveals a nonlinear signature that precedes progression of lung fibrosis

Objectives

Idiopathic pulmonary fibrosis (IPF) is a devastating progressive interstitial lung disease with poor outcomes. While decades of research have shed light on pathophysiological mechanisms associated with the disease, our understanding of the early molecular events driving IPF and its progression is limited. With this study, we aimed to model the leading edge of fibrosis using a data-driven approach.

Methods

Multiple omics modalities (transcriptomics, metabolomics and lipidomics) of healthy and IPF lung explants representing different stages of fibrosis were combined using an unbiased approach. Multi-Omics Factor Analysis of datasets revealed latent factors specifically linked with established fibrotic disease (Factor1) and disease progression (Factor2).

Results

Features characterising Factor1 comprised well-established hallmarks of fibrotic disease such as defects in surfactant, epithelial-mesenchymal transition, extracellular matrix deposition, mitochondrial dysfunction and purine metabolism. Comparatively, Factor2 identified a signature revealing a nonlinear trajectory towards disease progression. Molecular features characterising Factor2 included genes related to transcriptional regulation of cell differentiation, ciliogenesis and a subset of lipids from the endocannabinoid class. Machine learning models, trained upon the top transcriptomics features of each factor, accurately predicted disease status and progression when tested on two independent datasets.

Conclusion

This multi-omics integrative approach has revealed a unique signature which may represent the inflection point in disease progression, representing a promising avenue for the identification of therapeutic targets aimed at addressing the progressive nature of the disease.

Allosteric modulation of G protein-coupled receptors as a novel therapeutic strategy in neuropathic pain

Neuropathic pain is a debilitating pathological condition that presents significant therapeutic challenges in clinical practice. Unfortunately, current pharmacological treatments for neuropathic pain lack clinical efficacy and often lead to harmful adverse reactions. As G protein-coupled receptors (GPCRs) are widely distributed throughout the body, including the pain transmission pathway and descending inhibition pathway, the development of novel neuropathic pain treatments based on GPCRs allosteric modulation theory is gaining momentum. Extensive research has shown that allosteric modulators targeting GPCRs on the pain pathway can effectively alleviate symptoms of neuropathic pain while reducing or eliminating adverse effects. This review aims to provide a comprehensive summary of the progress made in GPCRs allosteric modulators in the treatment of neuropathic pain, and discuss the potential benefits and adverse factors of this treatment. We will also concentrate on the development of biased agonists of GPCRs, and based on important examples of biased agonist development in recent years, we will describe universal strategies for designing structure-based biased agonists. It is foreseeable that, with the continuous improvement of GPCRs allosteric modulation and biased agonist theory, effective GPCRs allosteric drugs will eventually be available for the treatment of neuropathic pain with acceptable safety.

Association between CNR1 gene polymorphisms and susceptibility to diabetic nephropathy in Iraqi patients with T2DM

In individuals with type 2 diabetes mellitus (T2DM), the cannabinoid receptor 1 (CNR1) gene polymorphism has been linked to diabetic nephropathy (DN). Different renal disorders, including DN, have been found to alter cannabinoid (CB) receptor expression and activation. This cross-sectional study aimed to investigate the relationship between CNR1 rs1776966256 and rs1243008337 genetic variants and the risk of developing DN in Iraqi patients with T2DM. The study included 100 patients with T2DM, divided into two groups: 50 with DN and 50 without DN. Genotyping of CNR1 rs1776966256 and rs1243008337 polymorphisms was conducted using PCR in DN patients and control samples. The distribution of rs1776966256 and rs1243008337 genotypes and alleles between the two groups revealed statistically significant differences. The frequencies of the GG and AG genotypes of CNR1 rs1776966256 were significantly different between DN patients and the control group. Additionally, compared to the A allele, the G allele of this polymorphism was linked to a higher incidence of DN (p=0.0001). Patients with the genetic polymorphism rs1243008337 had higher genotypes of CC and AC and were more likely to develop DN in the polymorphism genotype than the wild genotype. Additionally, compared to the A allele, the C allele was linked to a higher chance of developing DN (p=0.0001). Both rs1776966256 and rs1243008337 polymorphisms were correlated with the development of diabetic nephropathy.

Cannabinoformins: Designing Biguanide-Embedded, Orally Available, Peripherally Selective Cannabinoid-1 Receptor Antagonists for Metabolic Syndrome Disorders

We have designed orally bioavailable, non-brain-penetrant antagonists of the cannabinoid-1 receptor (CB1R) with a built-in biguanide sensor to mimic 5'-adenosine monophosphate kinase (AMPK) activation for treating obesity-associated co-morbidities. A series of 3,4-diarylpyrazolines bearing rational pharmacophoric pendants designed to limit brain penetration were synthesized and evaluated in CB1R ligand binding assays and recombinant AMPK assays. The compounds displayed high CB1R binding affinity and potent CB1R antagonist activities and acted as AMPK activators. Select compounds showed good oral exposure, with compounds 36, 38-S, and 39-S showing <5% brain penetrance, attesting to peripheral restriction. In vivo studies of 38-S revealed decreased food intake and body weight reduction in diet-induced obese mice as well as oral in vivo efficacy of 38-S in ameliorating glucose tolerance and insulin resistance. The designed "cannabinoformin" four-arm CB1R antagonists could serve as potential leads for treatment of metabolic syndrome disorders with negligible neuropsychiatric side effects.

Renal Endocannabinoid Dysregulation in Obesity-Induced Chronic Kidney Disease in Humans

The endocannabinoid system (ECS) regulates various physiological processes, including energy homeostasis and kidney function. ECS upregulation in obese animals and humans suggests a potential link to obesity-induced chronic kidney disease (CKD). However, obesity-induced ECS changes in the kidney are mainly studied in rodents, leaving the impact on obese humans unknown. In this study, a total of 21 lean and obese males (38-71 years) underwent a kidney biopsy. Biochemical analysis, histology, and endocannabinoid (eCB) assessment were performed on kidney tissue and blood samples. Correlations between different parameters were evaluated using a comprehensive matrix. The obese group exhibited kidney damage, reflected in morphological changes, and elevated kidney injury and fibrotic markers. While serum eCB levels were similar between the lean and obese groups, kidney eCB analysis revealed higher anandamide in obese patients. Obese individuals also exhibited reduced expression of cannabinoid-1 receptor (CB1R) in the kidney, along with increased activity of eCB synthesizing and degrading enzymes. Correlation analysis highlighted connections between renal eCBs, kidney injury markers, obesity, and related pathologies. In summary, this study investigates obesity's impact on renal eCB "tone" in humans, providing insights into the ECS's role in obesity-induced CKD. Our findings enhance the understanding of the intricate interplay among obesity, the ECS, and kidney function.

Goods and Bads of the Endocannabinoid System as a Therapeutic Target: Lessons Learned after 30 Years

The cannabis derivative marijuana is the most widely used recreational drug in the Western world and is consumed by an estimated 83 million individuals (∼3% of the world population). In recent years, there has been a marked transformation in society regarding the risk perception of cannabis, driven by its legalization and medical use in many states in the United States and worldwide. Compelling research evidence and the Food and Drug Administration cannabis-derived cannabidiol approval for severe childhood epilepsy have confirmed the large therapeutic potential of cannabidiol itself, Δ9-tetrahydrocannabinol and other plant-derived cannabinoids (phytocannabinoids). Of note, our body has a complex endocannabinoid system (ECS)-made of receptors, metabolic enzymes, and transporters-that is also regulated by phytocannabinoids. The first endocannabinoid to be discovered 30 years ago was anandamide (N-arachidonoyl-ethanolamine); since then, distinct elements of the ECS have been the target of drug design programs aimed at curing (or at least slowing down) a number of human diseases, both in the central nervous system and at the periphery. Here a critical review of our knowledge of the goods and bads of the ECS as a therapeutic target is presented to define the benefits of ECS-active phytocannabinoids and ECS-oriented synthetic drugs for human health. SIGNIFICANCE STATEMENT: The endocannabinoid system plays important roles virtually everywhere in our body and is either involved in mediating key processes of central and peripheral diseases or represents a therapeutic target for treatment. Therefore, understanding the structure, function, and pharmacology of the components of this complex system, and in particular of key receptors (like cannabinoid receptors 1 and 2) and metabolic enzymes (like fatty acid amide hydrolase and monoacylglycerol lipase), will advance our understanding of endocannabinoid signaling and activity at molecular, cellular, and system levels, providing new opportunities to treat patients.

Ang-(1-7) attenuates podocyte injury induced by high glucose in vitro

Objective

The incidence of diabetic nephropathy (DN) is gradually increasing worldwide. Podocyte injury, such as podocyte apoptosis and loss of the slit diaphragm (SD)-specific markers are early pathogenic features of DN.

Materials and methods

The cultured mouse podocytes were separated into a high glucose-treated (HG, 30mM) group to mimic DN in vitro, a low glucose-treated (LG, 5mM) group as a control and HG+ angiotensin-(1-7)(Ang-(1-7)) and HG+Ang-(1-7) + D-Ala7-Ang-(1-7) (A779, Ang-(1-7)/Mas receptor antagonist) experimental groups. The Cell Counting Kit-8 (CCK-8) method and flow cytometry was used to detect podocyte activity and podocyte apoptosis respectively. The expression of angiotensin type 1 receptor (AT1R), Mas receptor (MasR) and podocyte-specific markers were examined by q-PCR and Western blot, respectively.

Results

The results showed that the decrease in podocyte activity; the increase in podocyte apoptosis; the decreased mRNA and protein expression of nephrin, podocin, WT-1 and MasR; and the upregulated expression of AT1R induced by HG could be reversed by Ang-(1-7). However, these effects were blocked by A779. The possible mechanisms of the Ang-(1-7)-mediated effect depended on MasR. In addition, the protective effect of Ang-(1-7) on podocyte activity was dose-dependent and most obvious at 10 µM. A779 had the greatest antagonistic action against Ang-(1-7) at a concentration of 10 μM.

Conclusion

This study reveals that binding of Ang-(1-7) to its specific receptor MasR may counteract the effects of Ang II mediated by AT1R to significantly attenuate podocyte injury induced by high glucose. Ang-(1-7)/MasR targeting in podocytes may be a therapeutic approach to attenuate renal injury in DN.

Exploring the Therapeutic Potential of Cannabinoid Receptor Antagonists in Inflammation, Diabetes Mellitus, and Obesity

Recently, research has greatly expanded the knowledge of the endocannabinoid system (ECS) and its involvement in several therapeutic applications. Cannabinoid receptors (CBRs) are present in nearly every mammalian tissue, performing a vital role in different physiological processes (neuronal development, immune modulation, energy homeostasis). The ECS has an essential role in metabolic control and lipid signaling, making it a potential target for managing conditions such as obesity and diabetes. Its malfunction is closely linked to these pathological conditions. Additionally, the immunomodulatory function of the ECS presents a promising avenue for developing new treatments for various types of acute and chronic inflammatory conditions. Preclinical investigations using peripherally restricted CBR antagonists that do not cross the BBB have shown promise for the treatment of obesity and metabolic diseases, highlighting the importance of continuing efforts to discover novel molecules with superior safety profiles. The purpose of this review is to examine the roles of CB1R and CB2Rs, as well as their antagonists, in relation to the above-mentioned disorders.

An Integrative Multiomics Framework for Identification of Therapeutic Targets in Pulmonary Fibrosis

Pulmonary fibrosis (PF) is a heterogeneous disease with a poor prognosis. Therefore, identifying additional therapeutic modalities is required to improve outcome. However, the lack of biomarkers of disease progression hampers the preclinical to clinical translational process. Here, this work assesses and identifies progressive alterations in pulmonary function, transcriptomics, and metabolomics in the mouse lung at 7, 14, 21, and 28 days after a single dose of oropharyngeal bleomycin. By integrating multi-omics data, this work identifies two central gene subnetworks associated with multiple critical pathological changes in transcriptomics and metabolomics as well as pulmonary function. This work presents a multi-omics-based framework to establish a translational link between the bleomycin-induced PF model in mice and human idiopathic pulmonary fibrosis to identify druggable targets and test therapeutic candidates. This work also indicates peripheral cannabinoid receptor 1 (CB1 R) antagonism as a rational therapeutic target for clinical translation in PF. Mouse Lung Fibrosis Atlas can be accessed freely at https://niaaa.nih.gov/mouselungfibrosisatlas.

Cannabinoid Signaling in Kidney Disease

Endocannabinoid signaling plays crucial roles in human physiology in the function of multiple systems. The two cannabinoid receptors, CB1 and CB2, are cell membrane proteins that interact with both exogenous and endogenous bioactive lipid ligands, or endocannabinoids. Recent evidence has established that endocannabinoid signaling operates within the human kidney, as well as suggests the important role it plays in multiple renal pathologies. CB1, specifically, has been identified as the more prominent ECS receptor within the kidney, allowing us to place emphasis on this receptor. The activity of CB1 has been repeatedly shown to contribute to both diabetic and non-diabetic chronic kidney disease (CKD). Interestingly, recent reports of acute kidney injury (AKI) have been attributed to synthetic cannabinoid use. Therefore, the exploration of the ECS, its receptors, and its ligands can help provide better insight into new methods of treatment for a range of renal diseases. This review explores the endocannabinoid system, with a focus on its impacts within the healthy and diseased kidney.

Therapeutic potential of a novel peripherally restricted CB1R inverse agonist on the progression of diabetic nephropathy

Objective

This study assessed the efficacy of INV-202, a novel peripherally restricted cannabinoid type-1 receptor (CB1R) inverse agonist, in a streptozotocin-induced type-1 diabetes nephropathy mouse model.

Methods

Diabetes was induced in 8-week-old C57BL6/J male mice via intraperitoneal injection of streptozotocin (45 mg/kg/day for 5 days); nondiabetic controls received citrate buffer. Diabetic mice were randomized to 3 groups based on blood glucose, polyuria, and albuminuria, and administered daily oral doses for 28-days of INV-202 at 0.3 or 3 mg/kg or vehicle.

Results

INV-202 did not affect body weight but decreased kidney weight compared with the vehicle group. While polyuria was unaffected by INV-202 treatment, urinary urea (control 30.77 ± 14.93; vehicle 189.81 ± 31.49; INV-202 (0.3 mg/kg) 127.76 ± 20; INV-202 (3 mg/kg) 93.70 ± 24.97 mg/24h) and albumin (control 3.06 ± 0.38; vehicle 850.08 ± 170.50; INV-202 (0.3 mg/kg) 290.65 ± 88.70; INV-202 (3 mg/kg) 111.29 ± 33.47 µg/24h) excretion both decreased compared with vehicle-treated diabetic mice. Compared with the vehicle group, there was a significant improvement in the urinary albumin to creatinine ratio across INV-202 groups. Regardless of the dose, INV-202 significantly reduced angiotensin II excretion in diabetic mice. The treatment also decreased Agtr1a renal expression in a dose-dependent manner. Compared with nondiabetic controls, the glomerular filtration rate was increased in the vehicle group and significantly decreased by INV-202 at 3 mg/kg. While the vehicle group showed a significant loss in the mean number of podocytes per glomerulus, INV-202 treatment limited podocyte loss in a dose-dependent manner. Moreover, in both INV-202 groups, expression of genes coding for podocyte structural proteins nephrin (Nphs1), podocin (Nphs2), and podocalyxin (Pdxl) were restored to levels similar to nondiabetic controls. INV-202 partially limited the proximal tubular epithelial cell (PTEC) hyperplasia and normalized genetic markers for PTEC lesions. INV-202 also reduced expression of genes contributing to oxidative stress (Nox2, Nox4, and P47phox) and inflammation (Tnf). In addition, diabetes-induced renal fibrosis was significantly reduced by INV-202.

Conclusions

INV-202 reduced glomerular injury, preserved podocyte structure and function, reduced injury to PTECs, and ultimately reduced renal fibrosis in a streptozotocin-induced diabetic nephropathy mouse model. These results suggest that INV-202 may represent a new therapeutic option in the treatment of diabetic kidney disease.

Cannabidiol interacts with the FXR/Nrf2 pathway and changes the CB1/CB2 receptors ratio in gentamicin-induced kidney injury in rats

Objectives

Gentamicin-induced nephrotoxicity was used as an experimental model of kidney disease. The present study was performed to assess the therapeutic role of cannabidiol (CBD) against gentamicin-induced renal damage.

Materials and Methods

Forty two male Wistar rats were randomly allocated into 6 groups (n=7), including: (1) Control, (2) Vehicle, (3) Gentamicin-treated group (100 mg/kg/day) for 10 days (GM), (4-6) 3 Gentamicin-CBD-treated groups (2.5, 5, and 10 mg/kg/day) for 10 days (GM+CBD2.5, GM+CBD5, GM+CBD10). Serum levels of BUN and Cr, renal histology as well as real-time qRT-PCR were used to investigate the pattern of changes at different levels.

Results

Gentamicin increased serum BUN and Cr (P<0.001), down-regulation of FXR (P<0.001), SOD (P<0.05) and up-regulation of CB1 receptor mRNA (P<0.01). Compared to the control group, CBD at 5 decreased (P<0.05) and at 10 mg/kg/day increased the expression of FXR (P<0.05). Nrf2 expression in CBD groups was increased (P<0.001 vs. GM). The expression of TNF-α compared to the control and GM groups, was significantly increased in CBD2.5 (P<0.01) and CBD10 (P<0.05). Compared to the control, CBD at 2.5 (P<0.01), 5 (P<0.001) and 10 (P<0.001) mg/kg/day significantly increased the expression of CB1R. Up-regulation of CB1R in the GM+CBD5, was significantly higher (P<0.05) than the GM group. Compared to the control group, the most significant increase in CB2 receptor expression was observed at CBD10 (P<0.05).

Conclusion

CBD particularly at 10 mg/kg/day might be of significant therapeutic benefit against such renal complications. Activating the FXR/Nrf2 pathway and counteracting the deleterious effects of CB1 receptors via CB2 receptors scale-up could be part of the protective mechanisms of CBD.

Cannabis Use and Risk of Acute Kidney Injury in Patients with Advanced Chronic Kidney Disease Transitioning to Dialysis

Background: The current social and legal landscape is likely to foster the medicinal and recreational use of cannabis. Synthetic cannabinoid use is associated with acute kidney injury (AKI) in case reports; however, the association between natural cannabis use and AKI risk in patients with advanced chronic kidney disease (CKD) is unknown. Materials and Methods: From a nationally representative cohort of 102,477 U.S. veterans transitioning to dialysis between 2007 and 2015, we identified 2215 patients with advanced CKD who had undergone urine toxicology (UTOX) tests within a year before dialysis initiation and had inpatient serial serum creatinine levels measured within 7 days after their UTOX test. The exposure of interest was cannabis use compared with no use as ascertained by the UTOX test. We examined the association of this exposure with AKI using logistic regression and inverse probability of treatment weighting with extensive adjustment for potential confounders. Results: The mean age of the overall cohort was 61 years; 97% were males, 51% were African Americans, 97% had hypertension, 76% had hyperlipidemia, and 75% were diabetic. AKI occurred in 56% of the cohort, and in multivariable-adjusted analysis, cannabis use (when compared with no substance use) was not associated with significantly higher odds of AKI (odds ratio 0.85, 95% confidence interval 0.38-1.87; p=0.7). These results were robust to various sensitivity analyses. Conclusions: In this observational study examining patients with advanced CKD, cannabis use was not associated with AKI risk. Additional studies are needed to characterize the impact of cannabis use on risk of kidney disease and injury.

Network-based identification and prioritization of key transcriptional factors of diabetic kidney disease

Diabetic nephropathy (DN) is one of the most established microvascular complications of diabetes and a key cause of end-stage renal disease. It is well established that gene susceptibility to DN plays a critical role in disease pathophysiology. Therefore, many genetic studies have been performed to categorize candidate genes in prominent diabetic cohorts, aiming to investigate DN pathogenesis and etiology. In this study, we performed a meta-analysis on the expression profiles of GSE1009, GSE30122, GSE96804, GSE99340, GSE104948, GSE104954, and GSE111154 to identify critical transcriptional factors associated with DN progression. The analysis was conducted for all individual datasets for each kidney tissue (glomerulus, tubules, and kidney cortex). We identified distinct clusters of susceptibility genes that were dysregulated in a renal compartment-specific pattern. Further, we recognized a small but a closely connected set of these susceptibility genes enriched for podocyte differentiation, several of which were characterized as genes encoding critical transcriptional factors (TFs) involved in DN development and podocyte function. To validate the role of identified TFs in DN progression, we functionally validated the three main TFs (DACH1, LMX1B, and WT1) identified through differential gene expression and network analysis using the hyperglycemic zebrafish model. We report that hyperglycemia-induced altered gene expression of the key TF genes leads to morphological abnormalities in zebrafish glomeruli, pronephric tubules, proximal and distal ducts. This study demonstrated that altered expression of these TF genes could be associated with hyperglycemia-induced nephropathy and, thus, aids in understanding the molecular drivers, essential genes, and pathways that trigger DN initiation and development.

Blockade of CB1 or Activation of CB2 Cannabinoid Receptors Is Differentially Efficacious in the Treatment of the Early Pathological Events in Streptozotocin-Induced Diabetic Rats

Oxidative stress, neurodegeneration, neuroinflammation, and vascular leakage are believed to play a key role in the early stage of diabetic retinopathy (ESDR). The aim of this study was to investigate the blockade of cannabinoid receptor 1 (CB1R) and activation of cannabinoid receptor 2 (CB2R) as putative therapeutics for the treatment of the early toxic events in DR. Diabetic rats [streptozotocin (STZ)-induced] were treated topically (20 μL, 10 mg/mL), once daily for fourteen days (early stage DR model), with SR141716 (CB1R antagonist), AM1710 (CB2R agonist), and the dual treatment SR141716/AM1710. Immunohistochemical-histological, ELISA, and Evans-Blue analyses were performed to assess the neuroprotective and vasculoprotective properties of the pharmacological treatments on diabetes-induced retinal toxicity. Activation of CB2R or blockade of CB1R, as well as the dual treatment, attenuated the nitrative stress induced by diabetes. Both single treatments protected neural elements (e.g., RGC axons) and reduced vascular leakage. AM1710 alone reversed all toxic insults. These findings provide new knowledge regarding the differential efficacies of the cannabinoids, when administered topically, in the treatment of ESDR. Cannabinoid neuroprotection of the diabetic retina in ESDR may prove therapeutic in delaying the development of the advanced stage of the disease.

Cannabinoids and terpenes for diabetes mellitus and its complications: from mechanisms to new therapies

The number of people diagnosed with diabetes mellitus and its complications is markedly increasing worldwide, leading to a worldwide epidemic across all age groups, from children to older adults. Diabetes is associated with premature aging. In recent years, it has been found that peripheral overactivation of the endocannabinoid system (ECS), and in particular cannabinoid receptor 1 (CB1R) signaling, plays a crucial role in the progression of insulin resistance, diabetes (especially type 2), and its aging-related comorbidities such as atherosclerosis, nephropathy, neuropathy, and retinopathy. Therefore, it is suggested that peripheral blockade of CB1R may ameliorate diabetes and diabetes-related comorbidities. The use of synthetic CB1R antagonists such as rimonabant has been prohibited because of their psychiatric side effects. In contrast, phytocannabinoids such as cannabidiol (CBD) and tetrahydrocannabivarin (THCV), produced by cannabis, exhibit antagonistic activity on CB1R signaling and do not show any adverse side effects such as psychoactive effects, depression, or anxiety, thereby serving as potential candidates for the treatment of diabetes and its complications. In addition to these phytocannabinoids, cannabis also produces a substantial number of other phytocannabinoids, terpenes, and flavonoids with therapeutic potential against insulin resistance, diabetes, and its complications. In this review, the pathogenesis of diabetes, its complications, and the potential to use cannabinoids, terpenes, and flavonoids for its treatment are discussed.

The Contribution of Lipotoxicity to Diabetic Kidney Disease

Lipotoxicity is a fundamental pathophysiologic mechanism in diabetes and non-alcoholic fatty liver disease and is now increasingly recognized in diabetic kidney disease (DKD) pathogenesis. This review highlights lipotoxicity pathways in the podocyte and proximal tubule cell, which are arguably the two most critical sites in the nephron for DKD. The discussion focuses on membrane transporters and lipid droplets, which represent potential therapeutic targets, as well as current and developing pharmacologic approaches to reduce renal lipotoxicity.

Inactivation of fatty acid amide hydrolase protects against ischemic reperfusion injury-induced renal fibrogenesis

Although cannabinoid receptors (CB) are recognized as targets for renal fibrosis, the roles of endogenous cannabinoid anandamide (AEA) and its primary hydrolytic enzyme, fatty acid amide hydrolase (FAAH), in renal fibrogenesis remain unclear. The present study used a mouse model of post-ischemia-reperfusion renal injury (PIR) to test the hypothesis that FAAH participates in the renal fibrogenesis. Our results demonstrated that PIR showed upregulated expression of FAAH in renal proximal tubules, accompanied with decreased AEA levels in kidneys. Faah knockout mice recovered the reduced AEA levels and ameliorated PIR-triggered increases in blood urea nitrogen, plasma creatinine as well as renal profibrogenic markers and injuries. Correspondingly, a selective FAAH inhibitor, PF-04457845, inhibited the transforming growth factor-beta 1 (TGF-β1)-induced profibrogenic markers in human proximal tubular cell line (HK-2 cells) and mouse primary cultured tubular cells. Knockdown of FAAH by siRNA in HK-2 cells had similar effects as PF-04457845. Tubular cells isolated from Faah-/- mice further validated the protection against TGF-β1-induced damages. The CB 1 or CB2 receptor antagonist and exogenous FAAH metabolite arachidonic acid failed to reverse the protective effects of FAAH inactivation in HK-2 cells. However, a substrate-selective inhibitor of AEA-cyclooxygenase-2 (COX-2) pathway significantly suppressed the anti-profibrogenic actions of FAAH inhibition. Further, the AEA-COX-2 metabolite, prostamide E2 exerted anti-fibrogenesis effect. These findings suggest that FAAH activation and the consequent reduction of AEA contribute to the renal fibrogenesis, and that FAAH inhibition protects against fibrogenesis in renal cells independently of CB receptors via the AEA-COX-2 pathway by the recovery of reduced AEA.

Histone modification in podocyte injury of diabetic nephropathy

Diabetic nephropathy (DN), an important complication of diabetic microvascular disease, is one of the leading causes of end-stage renal disease (ESRD), which brings heavy burdens to the whole society. Podocytes are terminally differentiated glomerular cells, which act as a pivotal component of glomerular filtration barrier. When podocytes are injured, glomerular filtration barrier is damaged, and proteinuria would occur. Dysfunction of podocytes contributes to DN. And degrees of podocyte injury influence prognosis of DN. Growing evidences have shown that epigenetics does a lot in the evolvement of podocyte injury. Epigenetics includes DNA methylation, histone modification, and non-coding RNA. Among them, histone modification plays an indelible role. Histone modification includes histone methylation, histone acetylation, and other modifications such as histone phosphorylation, histone ubiquitination, histone ADP-ribosylation, histone crotonylation, and histone β-hydroxybutyrylation. It can affect chromatin structure and regulate gene transcription to exert its function. This review is to summarize documents about pathogenesis of podocyte injury, most importantly, histone modification of podocyte injury in DN recently to provide new ideas for further molecular research, diagnosis, and treatment.

Cross-Talk between the (Endo)Cannabinoid and Renin-Angiotensin Systems: Basic Evidence and Potential Therapeutic Significance

This review is dedicated to the cross-talk between the (endo)cannabinoid and renin angiotensin systems (RAS). Activation of AT1 receptors (AT1Rs) by angiotensin II (Ang II) can release endocannabinoids that, by acting at cannabinoid CB1 receptors (CB1Rs), modify the response to AT1R stimulation. CB1R blockade may enhance AT1R-mediated responses (mainly vasoconstrictor effects) or reduce them (mainly central nervous system-mediated effects). The final effects depend on whether stimulation of CB1Rs and AT1Rs induces opposite or the same effects. Second, CB1R blockade may diminish AT1R levels. Third, phytocannabinoids modulate angiotensin-converting enzyme-2. Additional studies are required to clarify (1) the existence of a cross-talk between the protective axis of the RAS (Ang II-AT2 receptor system or angiotensin 1-7-Mas receptor system) with components of the endocannabinoid system, (2) the influence of Ang II on constituents of the endocannabinoid system and (3) the (patho)physiological significance of AT1R-CB1R heteromerization. As a therapeutic consequence, CB1R antagonists may influence effects elicited by the activation or blockade of the RAS; phytocannabinoids may be useful as adjuvant therapy against COVID-19; single drugs acting on the (endo)cannabinoid system (cannabidiol) and the RAS (telmisartan) may show pharmacokinetic interactions since they are substrates of the same metabolizing enzyme of the transport mechanism.

Mechanisms of podocyte injury and implications for diabetic nephropathy

Albuminuria is the hallmark of both primary and secondary proteinuric glomerulopathies, including focal segmental glomerulosclerosis (FSGS), obesity-related nephropathy, and diabetic nephropathy (DN). Moreover, albuminuria is an important feature of all chronic kidney diseases (CKDs). Podocytes play a key role in maintaining the permselectivity of the glomerular filtration barrier (GFB) and injury of the podocyte, leading to foot process (FP) effacement and podocyte loss, the unifying underlying mechanism of proteinuric glomerulopathies. The metabolic insult of hyperglycemia is of paramount importance in the pathogenesis of DN, while insults leading to podocyte damage are poorly defined in other proteinuric glomerulopathies. However, shared mechanisms of podocyte damage have been identified. Herein, we will review the role of haemodynamic and oxidative stress, inflammation, lipotoxicity, endocannabinoid (EC) hypertone, and both mitochondrial and autophagic dysfunction in the pathogenesis of the podocyte damage, focussing particularly on their role in the pathogenesis of DN. Gaining a better insight into the mechanisms of podocyte injury may provide novel targets for treatment. Moreover, novel strategies for boosting podocyte repair may open the way to podocyte regenerative medicine.

Opposite physiological and pathological mTORC1-mediated roles of the CB1 receptor in regulating renal tubular function

Activation of the cannabinoid-1 receptor (CB₁R) and the mammalian target of rapamycin complex 1 (mTORC1) in the renal proximal tubular cells (RPTCs) contributes to the development of diabetic kidney disease (DKD). However, the CB₁R/mTORC1 signaling axis in the kidney has not been described yet. We show here that hyperglycemia-induced endocannabinoid/CB₁R stimulation increased mTORC1 activity, enhancing the transcription of the facilitative glucose transporter 2 (GLUT2) and leading to the development of DKD in mice; this effect was ameliorated by specific RPTCs ablation of GLUT2. Conversely, CB₁R maintained the normal activity of mTORC1 by preventing the cellular excess of amino acids during normoglycemia. Our findings highlight a novel molecular mechanism by which the activation of mTORC1 in RPTCs is tightly controlled by CB₁R, either by enhancing the reabsorption of glucose and inducing kidney dysfunction in diabetes or by preventing amino acid uptake and maintaining normal kidney function in healthy conditions.

Renal proximal tubules modulate whole-body homeostasis by sensing various nutrients. Here the authors describe the existence and importance of a unique CB1/mTORC1/GLUT2 signaling axis in regulating nutrient homeostasis in healthy and diseased kidney.

Glomerular Biomechanical Stress and Lipid Mediators during Cellular Changes Leading to Chronic Kidney Disease

Hyperfiltration is an important underlying cause of glomerular dysfunction associated with several systemic and intrinsic glomerular conditions leading to chronic kidney disease (CKD). These include obesity, diabetes, hypertension, focal segmental glomerulosclerosis (FSGS), congenital abnormalities and reduced renal mass (low nephron number). Hyperfiltration-associated biomechanical forces directly impact the cell membrane, generating tensile and fluid flow shear stresses in multiple segments of the nephron. Ongoing research suggests these biomechanical forces as the initial mediators of hyperfiltration-induced deterioration of podocyte structure and function leading to their detachment and irreplaceable loss from the glomerular filtration barrier. Membrane lipid-derived polyunsaturated fatty acids (PUFA) and their metabolites are potent transducers of biomechanical stress from the cell surface to intracellular compartments. Omega-6 and ω-3 long-chain PUFA from membrane phospholipids generate many versatile and autacoid oxylipins that modulate pro-inflammatory as well as anti-inflammatory autocrine and paracrine signaling. We advance the idea that lipid signaling molecules, related enzymes, metabolites and receptors are not just mediators of cellular stress but also potential targets for developing novel interventions. With the growing emphasis on lifestyle changes for wellness, dietary fatty acids are potential adjunct-therapeutics to minimize/treat hyperfiltration-induced progressive glomerular damage and CKD.

Endocannabinoid System in Polycystic Kidney Disease

INTRODUCTION

Autosomal dominant polycystic kidney disease (ADPKD) is a commonly inherited disorder characterized by renal cyst formation. A major pathological feature of ADPKD is the development of interstitial inflammation. The endocannabinoid (EC) system is present in the kidney and has recently emerged as an important player in inflammation and the pathogenesis of progressive kidney disease.

METHODS

Data on ECs were collected using a validated mass spectrometry assay from a well-characterized cohort of 102 ADPKD patients (at baseline and after 2- and 4 years on standard vs. rigorous blood-pressure control) and compared to 100 healthy subjects.

RESULTS

Compared to healthy individuals, we found higher interleukins-6 and -1b as well as reduced plasma levels of anandamide (AEA), 2-arachidonoyl-glycerol (2-AG), and their congeners in ADPKD patients. Baseline AEA concentration negatively associated with the progression of ADPKD as expressed by the yearly percent change in height-corrected total kidney volume and positively with the yearly change in renal function (measured as estimated glomerular filtration rate, ΔeGFR). AEA analog palmitoylethanolamide (PEA) is also associated positively with the yearly change in eGFR.

DISCUSSION AND CONCLUSION

The results of the present study suggest that ADPKD patients present with lower levels of ECs and that reestablishing the normality of the renal EC system via augmentation of AEA, PEA, and 2-AG levels, either through the increase of their synthesis or through a reduction of their degradation, could be beneficial and may present a promising therapeutic target in said patients.

Detrimental Effect of Cannabidiol on the Early Onset of Diabetic Nephropathy in Male Mice

Anti-inflammatory and antidiabetogenic properties have been ascribed to cannabidiol (CBD). CBD-based medicinal drugs have been approved for over a lustrum, and a boom in the commercialization of CBD products started in parallel. Herein, we explored the efficacy of CBD in streptozotocin (STZ)-induced diabetic mice to prevent diabetic nephropathy at onset. Eight-to-ten-week-old C57BL6J male mice were treated daily intraperitoneally with 10 mg/kg of CBD or vehicle for 14 days. After 8 days of treatment, mice were challenged with STZ or vehicle (healthy-control). At the end of the study, non-fasting blood glucose (FBG) level was 276 ± 42 mg/dL in vehicle-STZ-treated compared to 147 ± 9 mg/dL (p ≤ 0.01) in healthy-control mice. FBG was 114 ± 8 mg/dL in vehicle-STZ-treated compared to 89 ± 4 mg/dL in healthy-control mice (p ≤ 0.05). CBD treatment did not prevent STZ-induced hyperglycemia, and non-FBG and FBG levels were 341 ± 40 and 133 ± 26 mg/dL, respectively. Additionally, treatment with CBD did not avert STZ-induced glucose intolerance or pancreatic beta cell mass loss compared to vehicle-STZ-treated mice. Anatomopathological examination showed that kidneys from vehicle-STZ-treated mice had a 35% increase of glomerular size compared to healthy-control mice (p ≤ 0.001) and presented lesions with a 43% increase in fibrosis and T cell infiltration (p ≤ 0.001). Although treatment with CBD prevented glomerular hypertrophy and reduced T cell infiltration, it significantly worsened overall renal damage (p ≤ 0.05 compared to vehicle-STZ mice), leading to a more severe renal dysfunction than STZ alone. In conclusion, we showed that CBD could be detrimental for patients with type 1 diabetes, particularly those undergoing complications such as diabetic nephropathy.

Peripheral CB1R as a modulator of metabolic inflammation

Obesity is associated with chronic inflammation in insulin-sensitive tissues, including liver and adipose tissue, and causes hormonal/metabolic complications, such as insulin resistance. There is growing evidence that peripheral cannabinoid-type 1 receptor (CB1R) is a crucial participant in obesity-induced pro-inflammatory responses in insulin-target tissues, and its selective targeting could be a novel therapeutic strategy to break the link between insulin resistance and metabolic inflammation. In this review, we introduce the role of peripheral CB1R in metabolic inflammation and as a mediator of hormonal/metabolic complications that underlie metabolic syndrome, including fatty liver, insulin resistance, and dyslipidemia. We also discuss the therapeutic potential of second- and third-generation peripherally restricted CB1R antagonists for treating obesity-induced metabolic inflammation without eliciting central CB1R-mediated neurobehavioral effects, predictive of neuropsychiatric side effects, in humans.

Role of endocannabinoid CB1 receptors in Streptozotocin-induced uninephrectomised Wistar rats in diabetic nephropathy

Background

The endocannabinoid CB1 receptor is known to have protective effects in kidney disease. The aim of the present study is to evaluate the potential agonistic and antagonistic actions and to determine the renoprotective potential of CB1 receptors in diabetic nephropathy. The present work investigates the possible role of CB1 receptors in the pathogenesis of diabetes-induced nephropathy. Streptozotocin (STZ) (55 mg/kg, i.p., once) is administered to uninephrectomised rats for induction of experimental diabetes mellitus. The CB1 agonist (oleamide) and CB1 antagonist (AM6545) treatment were initiated in diabetic rats after 1 week of STZ administration and were given for 24 weeks.

Results

The progress in diabetic nephropathy is estimated biochemically by measuring serum creatinine (1.28±0.03) (p < 0.005), blood urea nitrogen (67.6± 2.10) (p < 0.001), urinary microprotein (74.62± 3.47) (p < 0.005) and urinary albuminuria (28.31±1.17) (p < 0.0001). Renal inflammation was assessed by estimating serum levels of tumor necrosis factor alpha (75.69±1.51) (p < 0.001) and transforming growth factor beta (8.73±0.31) (p < 0.001). Renal morphological changes were assessed by estimating renal hypertrophy (7.38± 0.26) (p < 0.005) and renal collagen content (10.42± 0.48) (p < 0.001).

Conclusions

From the above findings, it can be said that diabetes-induced nephropathy may be associated with overexpression of CB1 receptors and blockade of CB1 receptors might be beneficial in ameliorating the diabetes-induced nephropathy.

Graphical abstract

(+)-trans-Cannabidiol-2-hydroxy pentyl is a dual CB1R antagonist/CB2R agonist that prevents diabetic nephropathy in mice

Natural cannabidiol ((-)-CBD) and its derivatives have increased interest for medicinal applications due to their broad biological activity spectrum, including targeting of the cannabinoid receptors type 1 (CB₁R) and type 2 (CB₂R). Herein, we synthesized the (+)-enantiomer of CBD and its derivative (+)-CBD hydroxypentylester ((+)-CBD-HPE) that showed enhanced CB₁R and CB₂R binding and functional activities compared to their respective (-) enantiomers. (+)-CBD-HPE Ki values for CB₁R and CB₂R were 3.1 ± 1.1 and 0.8 ± 0.1 nM respectively acting as CB₁R antagonist and CB₂R agonist. We further tested the capacity of (+)-CBD-HPE to prevent hyperglycemia and its complications in a mouse model. (+)-CBD-HPE significantly reduced streptozotocin (STZ)-induced hyperglycemia and glucose intolerance by preserving pancreatic beta cell mass. (+)-CBD-HPE significantly reduced activation of NF-κB by phosphorylation by 15% compared to STZ-vehicle mice, and CD3⁺ T cell infiltration into the islets was avoided. Consequently, (+)-CBD-HPE prevented STZ-induced apoptosis in islets. STZ induced inflammation and kidney damage, visualized by a significant increase in plasma proinflammatory cytokines, creatinine, and BUN. Treatment with (+)-CBD-HPE significantly reduced 2.5-fold plasma IFN-γ and increased 3-fold IL-5 levels compared to STZ-treated mice, without altering IL-18. (+)-CBD-HPE also significantly reduced creatinine and BUN levels to those comparable to healthy controls. At the macroscopy level, (+)-CBD-HPE prevented STZ-induced lesions in the kidney and voided renal fibrosis and CD3⁺ T cell infiltration. Thus, (+)-enantiomers of CBD, particularly (+)-CBD-HPE, have a promising potential due to their pharmacological profile and synthesis, potentially to be used for metabolic and immune-related disorders.

Curcumin Reinforces MiR-29a Expression, Reducing Mesangial Fibrosis in a Model of Diabetic Fibrotic Kidney via Modulation of CB1R Signaling

Renal fibrosis is a hallmark event in the pathogenesis of diabetic nephropathy. Considerable evidence now supports that multiple intracellular signaling pathways are critically involved in renal fibrosis. Previously, our studies have shown that dysregulation of the MicroRNA 29a (miR-29a)- or cannabinoid type 1 receptor (CB1R)-mediated signaling cascade in renal glomeruli substantially contributes to diabetic renal fibrosis. The purpose of the current study was to explore whether curcumin, a natural polyphenolic compound with potential renoprotective activity, could modulate the miR-29a/CB1R signaling axis to attenuate renal fibrosis. In this study, rat renal mesangial cells cultured in high glucose (HG) and the diabetic db/db mice were used as an in vitro and in vivo model of diabetes, respectively. Our results showed that in rat renal mesangial cells, curcumin treatment substantially counteracted HG-induced changes in the expressions of miR-29a, CB1R, peroxisome proliferator-activated receptor gamma (PPAR-γ), and a profibrotic marker type IV collagen (collagen IV), as assessed by quantitative Real-Time Polymerase chain reaction (RT-PCR). Furthermore, in the db/db mouse model, administration of curcumin markedly lowered urinary albumin excretion, and reduced deposition of extracellular matrices including collagen IV in renal tissues. Importantly, quantitative RT-PCR, in situ hybridization, and immunohistochemical analysis revealed that curcumin treatment consistently blocked diabetes-induced downregulation of miR-29a and upregulation of CB1R in renal glomeruli. Collectively, our study provides novel evidence showing that curcumin can rescue the dysregulated miR-29a/CB1R signaling pathway in glomerular mesangium to ameliorate diabetic renal fibrosis.

Dual inhibition of CB1 receptors and iNOS, as a potential novel approach to the pharmacological management of acute and long COVID-19

COVID‐19 (SARS‐CoV‐2) causes multiple inflammatory complications, resulting not only in severe lung inflammation but also harm to other organs. Although the current focus is on the management of acute COVID‐19, there is growing concern about long‐term effects of COVID‐19 (Long Covid), such as fibroproliferative changes in the lung, heart and kidney. Therefore, the identification of therapeutic targets not only for the management of acute COVID‐19 but also for preventing Long Covid are needed, and would mitigate against long‐lasting health burden and economic costs, in addition to saving lives. COVID‐19 induces pathological changes via multiple pathways, which could be targeted simultaneously for optimal effect. We discuss the potential pathologic function of increased activity of the endocannabinoid/CB₁ receptor system and inducible NO synthase (iNOS). We advocate a polypharmacology approach, wherein a single chemical entity simultaneously interacts with CB₁ receptors and iNOS causing inhibition, as a potential therapeutic strategy for COVID‐19‐related health complications.

Renal Proximal Tubule Cell Cannabinoid-1 Receptor Regulates Bone Remodeling and Mass via a Kidney-to-Bone Axis

The renal proximal tubule cells (RPTCs), well-known for maintaining glucose and mineral homeostasis, play a critical role in the regulation of kidney function and bone remodeling. Deterioration in RPTC function may therefore lead to the development of diabetic kidney disease (DKD) and osteoporosis. Previously, we have shown that the cannabinoid-1 receptor (CB1R) modulates both kidney function as well as bone remodeling and mass via its direct role in RPTCs and bone cells, respectively. Here we employed genetic and pharmacological approaches that target CB1R, and found that its specific nullification in RPTCs preserves bone mass and remodeling both under normo- and hyper-glycemic conditions, and that its chronic blockade prevents the development of diabetes-induced bone loss. These protective effects of negatively targeting CB1R specifically in RPTCs were associated with its ability to modulate erythropoietin (EPO) synthesis, a hormone known to affect bone mass and remodeling. Our findings highlight a novel molecular mechanism by which CB1R in RPTCs remotely regulates skeletal homeostasis via a kidney-to-bone axis that involves EPO.

Interference with TGFβ1-Mediated Inflammation and Fibrosis Underlies Reno-Protective Effects of the CB1 Receptor Neutral Antagonists AM6545 and AM4113 in a Rat Model of Metabolic Syndrome

The role of cannabinoid receptors in nephropathy is gaining much attention. This study investigated the effects of two neutral CB1 receptor antagonists, AM6545 and AM4113, on nephropathy associated with metabolic syndrome (MetS). MetS was induced in rats by high-fructose high-salt feeding for 12 weeks. AM6545, the peripheral silent antagonist and AM4113, the central neutral antagonist were administered in the last 4 weeks. At the end of study, blood and urine samples were collected for biochemical analyses while the kidneys were excised for histopathological investigation and transforming growth factor beta 1 (TGFβ1) measurement. MetS was associated with deteriorated kidney function as indicated by the elevated proteinuria and albumin excretion rate. Both compounds equally inhibited the elevated proteinuria and albumin excretion rate while having no effect on creatinine clearance and blood pressure. In addition, AM6545 and AM4113 alleviated the observed swelling and inflammatory cells infiltration in different kidney structures. Moreover, AM6545 and AM4113 alleviated the observed histopathological alterations in kidney structure of MetS rats. MetS was associated with a ten-fold increase in urine uric acid while both compounds blocked this increase. Furthermore, AM6545 and AM4113 completely prevented the collagen deposition and the elevated expression of the TGFβ1 seen in MetS animals. In conclusion, AM6545 and AM4113, possess reno-protective effects by interfering with TGFβ1-mediated renal inflammation and fibrosis, via peripheral action.

Optimization of the Heterologous Expression of the Cannabinoid Type-1 (CB1) Receptor

The G protein-coupled type 1 cannabinoid receptor (CB₁R) mediates virtually all classic cannabinoid effects, and both its agonists and antagonists hold major therapeutic potential. Heterologous expression of receptors is vital for pharmacological research, however, overexpression of these proteins may fundamentally alter their localization pattern, change the signalling partner preference and may also spark artificial clustering. Additionally, recombinant CB₁Rs are prone to intense proteasomal degradation, which may necessitate substantial modifications, such as N-terminal truncation or signal sequence insertion, for acceptable cell surface expression. We report here that tuning down the expression intensity of the full-length CB₁R reduces proteasomal degradation and offers receptor levels that are comparable to those of endogenous CB₁ receptors. As opposed to high-efficiency expression with conventional promoters, weak promoter-driven CB₁R expression provides ERK 1/2 and p38 MAPK signalling that closely resemble the activity of endogenous CB₁Rs. Moreover, weakly expressed CB₁R variants exhibit plasma membrane localization, preserve canonical G_i-signalling but prevent CB₁R-G_s coupling observed with high-expression variants. Based on these findings, we propose that lowering the expression level of G protein-coupled receptors should always be considered in heterologous expression systems in order to reduce the pressure on the proteasomal machinery and to avoid potential signalling artefacts.

Cannabinoid Receptor 1 Inhibition in Chronic Kidney Disease: A New Therapeutic Toolbox

Chronic kidney disease (CKD) concerns millions of individuals worldwide, with few therapeutic strategies available to date. Recent evidence suggests that the endocannabinoid system (ECS) could be a new therapeutic target to prevent CKD. ECS combines receptors, cannabinoid receptor type 1 (CB1R) and type 2 (CB2R), and ligands. The most prominent receptor within the kidney is CB1R, its endogenous local ligands being anandamide and 2-arachidonoylglycerol. Therefore, the present review focuses on the therapeutic potential of CB1R and not CB2R. In the normal kidney, CB1R is expressed in many cell types, especially in the vasculature where it contributes to the regulation of renal hemodynamics. CB1R could also participate to water and sodium balance and to blood pressure regulation but its precise role remains to decipher. CB1R promotes renal fibrosis in both metabolic and non-metabolic nephropathies. In metabolic syndrome, obesity and diabetes, CB1R inhibition not only improves metabolic parameters, but also exerts a direct role in preventing renal fibrosis. In non-metabolic nephropathies, its inhibition reduces the development of renal fibrosis. There is a growing interest of the industry to develop new CB1R antagonists without central nervous side-effects. Experimental data on renal fibrosis are encouraging and some molecules are currently under early-stage clinical phases (phases I and IIa studies). In the present review, we will first describe the role of the endocannabinoid receptors, especially CB1R, in renal physiology. We will next explore the role of endocannabinoid receptors in both metabolic and non-metabolic CKD and renal fibrosis. Finally, we will discuss the therapeutic potential of CB1R inhibition using the new pharmacological approaches. Overall, the new pharmacological blockers of CB1R could provide an additional therapeutic toolbox in the management of CKD and renal fibrosis from both metabolic and non-metabolic origin.

Deciphering the cellular mechanisms underlying fibrosis-associated diseases and therapeutic avenues

Fibrosis is the excessive deposition of extracellular matrix components, which results in disruption of tissue architecture and loss of organ function. Fibrosis leads to high morbidity and mortality worldwide, mainly due to the lack of effective therapeutic strategies against fibrosis. It is generally accepted that fibrosis occurs during an aberrant wound healing process and shares a common pathogenesis across different organs such as the heart, liver, kidney, and lung. A better understanding of the fibrosis-related cellular and molecular mechanisms will be helpful for development of targeted drug therapies. Extensive studies revealed that numerous mediators contributed to fibrogenesis, suggesting that targeting these mediators may be an effective therapeutic strategy for antifibrosis. In this review, we describe a number of mediators involved in tissue fibrosis, including aryl hydrocarbon receptor, Yes-associated protein, cannabinoid receptors, angiopoietin-like protein 2, high mobility group box 1, angiotensin-converting enzyme 2, sphingosine 1-phosphate receptor-1, SH2 domain-containing phosphatase-2, and long non-coding RNAs, with the goal that drugs targeting these important mediators might exhibit a beneficial effect on antifibrosis. In addition, these mediators show profibrotic effects on multiple tissues, suggesting that targeting these mediators will exert antifibrotic effects on different organs. Furthermore, we present a variety of compounds that exhibit therapeutic effects against fibrosis. This review suggests therapeutic avenues for targeting organ fibrosis and concurrently identifies challenges and opportunities for designing new therapeutic strategies against fibrosis.

Bioactive lipids, inflammation and chronic diseases

Endogenous bioactive lipids are part of a complex network that modulates a plethora of cellular and molecular processes involved in health and disease, of which inflammation represents one of the most prominent examples. Inflammation serves as a well-conserved defence mechanism, triggered in the event of chemical, mechanical or microbial damage, that is meant to eradicate the source of damage and restore tissue function. However, excessive inflammatory signals, or impairment of pro-resolving/anti-inflammatory pathways leads to chronic inflammation, which is a hallmark of chronic pathologies. All main classes of endogenous bioactive lipids - namely eicosanoids, specialized pro-resolving lipid mediators, lysoglycerophopsholipids and endocannabinoids - have been consistently involved in the chronic inflammation that characterises pathologies such as cancer, diabetes, atherosclerosis, asthma, as well as autoimmune and neurodegenerative disorders and inflammatory bowel diseases. This review gathers the current knowledge concerning the involvement of endogenous bioactive lipids in the pathogenic processes of chronic inflammatory pathologies.