Increased Renal 2-Arachidonoylglycerol Level Is Associated with Improved Renal Function in a Mouse Model of Acute Kidney Injury

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.

Novel MAGL Inhibitors Alleviate LPS-Induced Acute Kidney Injury by Inhibiting NLRP3 Inflammatory Vesicles, Modulating Intestinal Flora, Repairing the Intestinal Barrier, and Interfering with Serum Metabolism

Acute kidney injury (AKI) is a complication of a wide range of serious illnesses for which there is still no better therapeutic agent. We demonstrated that M-18C has a favorable inhibitory effect on monoacylglycerol lipase (MAGL), and several studies have demonstrated that nerve inflammation could be effectively alleviated by inhibiting MAGL, suggesting that M-18C has good anti-inflammatory activity. In this study, we investigated the effect of M-18C on LPS-induced acute kidney injury (AKI), both in vivo and in vitro, by using liquid chromatography-mass spectrometry (LC-MS), 16S rRNA gene sequencing, Western blot, and immunohistochemistry. The results showed that both in vivo and in vitro M-18C reduced the release of TNF-α and IL-1β by inhibiting the expression of NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) and apoptosis-associated speck-like protein containing a CARD (ASC) protein; in addition, M-18C was able to intervene in LPS-induced AKI by ameliorating renal pathological injury, repairing the intestinal barrier, and regulating gut bacterial flora and serum metabolism. In conclusion, this study suggests that M-18C has the potential to be a new drug for the treatment of AKI.

Peripheral Cannabinoid-1 Receptor Blockade Ameliorates Cystitis Severity

Background: The endocannabinoid system (ECS) plays a key physiological role in bladder function and it has been suggested as a potential target for relieving lower urinary tract symptoms (LUTSs). Whereas most studies indicate that activating the ECS has some beneficial effects on the bladder, some studies imply the opposite. In this study, we investigated the therapeutic potential of peripheral cannabinoid-1 receptor (CB1R) blockade in a mouse model for LUTSs. Materials and Methods: To this end, we used the cyclophosphamide (CYP; 300 mg/kg, intraperitoneal)-induced cystitis model of bladder dysfunction, in which 12-week-old, female C57BL/6 mice were treated with the peripherally restricted CB1R antagonist, JD5037 (3 mg/kg), or vehicle for three consecutive days. Bladder dysfunction was assessed using the noninvasive voiding spot assay (VSA) as well as the bladder-to-body weight (BW) ratio and gene and protein expression levels; ECS tone was assessed at the end of the study. Results: Peripheral CB1R blockade significantly ameliorated the severity of CYP-induced cystitis, manifested by reduced urination events measured in the VSA and an increased bladder-to-BW ratio. Moreover, JD5037 normalized CYP-mediated bladder ECS tone imbalance by affecting both the expression of CB1R and the endocannabinoid levels. These effects were associated with the ability of JD5037 to reduce CYP-induced inflammatory response, manifested by a reduction in levels of the proinflammatory cytokine, tumor necrosis factor alpha (TNFα), in the bladder and serum. Conclusions: Collectively, our results highlight the therapeutic relevance of peripheral CB1R blockade in ameliorating CYP-induced cystitis; they may further support the preclinical development and clinical use of peripherally restricted CB1R antagonism for treatment of LUTSs.

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.

Genetic Knockout of Fatty Acid Amide Hydrolase Ameliorates Cisplatin-Induced Nephropathy in Mice

Cisplatin is a potent first-line therapy for many solid malignancies, such as breast, ovarian, lung, testicular, and head and neck cancer. However, acute kidney injury (AKI) is a major dose-limiting toxicity in cisplatin therapy, which often hampers the continuation of cisplatin treatment. The endocannabinoid system, consisting of anandamide (AEA) and 2-arachidonoylglycerol and cannabinoid receptors, participates in different kidney diseases. Inhibition of fatty acid amide hydrolase (FAAH), the primary enzyme for the degradation of AEA and AEA-related N-acylethanolamines, elicits anti-inflammatory effects; however, little is known about its role in cisplatin nephrotoxicity. The current study tested the hypothesis that genetic deletion of Faah mitigates cisplatin-induced AKI. Male wild-type C57BL6 (WT) and Faah-/- mice were administered a single dose of intraperitoneal injection of cisplatin (30 mg/kg) and euthanatized 72 hours later. Faah-/- mice showed a reduction of cisplatin-induced blood urea nitrogen, plasma creatinine levels, kidney injury markers, and tubular damage in comparison with WT mice. The renal protection from Faah deletion was associated with enhanced tone of AEA-related N-acylethanolamines (palmitoylethanolamide and oleoylethanolamide), attenuated nuclear factor-κB/p65 activity, DNA damage markers p53 and p21, and decreased expression of the inflammatory cytokine interleukin-1β, as well as infiltration of macrophages and leukocytes in the kidneys. Notably, a selective FAAH inhibitor (PF-04457845) did not interfere with or perturb the antitumor effects of cisplatin in two head and neck squamous cell carcinoma cell lines, HN30 and HN12. Our work highlights that FAAH inactivation prevents cisplatin-induced nephrotoxicity in mice and that targeting FAAH could provide a novel strategy to mitigate cisplatin-induced nephrotoxicity. SIGNIFICANCE STATEMENT: Mice lacking the Faah gene are protected from cisplatin-induced inflammation, DNA damage response, tubular damage, and kidney dysfunction. Inactivation of FAAH could be a potential strategy to mitigate cisplatin-induced nephrotoxicity.

Analysis of fatty acid composition and sensitivity to dietary n-3 PUFA intervention of mouse n-3 PUFA-enriched tissues/organs

PURPOSE

n-3 polyunsaturated fatty acids (PUFAs), docosahexaenoic acid (DHA; C22:6 n3) and eicosapentaenoic acid (EPA; C20:5 n3), are of concern for their health-promoting effects such as anti-inflammatory, but the tissue selectivity for n-3 PUFA (i.e., which tissues and organs are rich in n-3 PUFA) is still not well known. In addition, it is unclear which tissues and organs are more sensitive to n-3 PUFA intervention. These unresolved issues have greatly hindered the exploring of the health benefits of n-3 PUFA.

METHODS

Twenty-four 7-week-old male C57BL/6 J mice were assigned to the control, fish oil, DHA, and EPA groups. The last three groups were given a 4-week oral intervention of fatty acids in ethyl ester (400 mg/kg bw). The fatty acid profiles in 27 compartments were determined by gas chromatography.

RESULTS

The proportion of long-chain n-3 PUFA (the total relative percentage of EPA, DPA n3, and DHA) was analyzed. Eight tissues and organs, including the brain (cerebral cortex, hippocampus, hypothalamus) and peripheral organs (tongue, quadriceps, gastrocnemius, kidney, and heart) were determined as being n-3 PUFA-enriched tissues and organs, owing to their high n-3 PUFA levels. The highest n-3 PUFA content was observed in the tongue for the first time. Notably, the content of linoleic acid (LA; C18:2 n6c) in peripheral organs was observed to be relatively high compared with that in the brain. Interestingly, the proportions of EPA in the kidney, heart, quadriceps, gastrocnemius, and tongue increased more markedly after the EPA intervention than after the DHA or fish oil intervention. As expected, the levels of proinflammatory arachidonic acid (AA; C20:4 n6) in the kidney, quadriceps, and tongue were markedly decreased after the three dietary interventions.

CONCLUSION

Peripheral tissues and organs, including the tongue, quadriceps, gastrocnemius, kidney, and heart, besides the brain, showed obvious tissue selectivity for n-3 PUFA. In the whole body of mice, the tongue exhibits the strongest preference for n-3 PUFA, with the highest proportion of n-3 PUFA. Moreover, these peripheral tissues and organs, especially the kidney, are more sensitive to dietary EPA administration in comparison with the brain.

Systemic Changes in Endocannabinoids and Endocannabinoid-like Molecules in Response to Partial Nephrectomy-Induced Ischemia in Humans

Renal ischemia-reperfusion (IR), a routine feature of partial nephrectomy (PN), can contribute to the development of acute kidney injury (AKI). Rodent studies show that the endocannabinoid system (ECS) is a major regulator of renal hemodynamics and IR injury; however, its clinical relevance remains to be established. Here, we assessed the clinical changes in systemic endocannabinoid (eCB) levels induced by surgical renal IR. Sixteen patients undergoing on-clamp PN were included, with blood samples taken before renal ischemia, after 10 min of ischemia time, and 10 min following blood reperfusion. Kidney function parameters (serum creatinine (sCr), blood urea nitrogen (BUN), and serum glucose) and eCB levels were measured. Baseline levels and individual changes in response to IR were analyzed and correlation analyses were performed. The baseline levels of eCB 2-arachidonoylglycerol (2-AG) were positively correlated with kidney dysfunction biomarkers. Unilateral renal ischemia increased BUN, sCr, and glucose, which remained elevated following renal reperfusion. Renal ischemia did not induce changes in eCB levels for all patients pooled together. Nevertheless, stratifying patients according to their body mass index (BMI) revealed a significant increase in N-acylethanolamines (anandamide, AEA; N-oleoylethanolamine, OEA; and N-palmitoylethanolamine, PEA) in the non-obese patients. No significant changes were found in obese patients who had higher N-acylethanolamines baseline levels, positively correlated with BMI, and more cases of post-surgery AKI. With the inefficiency of 'traditional' IR-injury 'preventive drugs', our data support future research on the role of the ECS and its manipulation in renal IR.

Protective effect of fatty acid amide hydrolase inhibitor URB597 and monoacylglycerol lipase inhibitor KML29 on renal ischemia-reperfusion injury via toll-like receptor 4/nuclear factor-kappa B pathway

BACKGROUND

Arachidonoyl ethanolamide (anandamide, AEA) and 2-arachidonoylglycerol (2-AG) are the most studies endocannabinoids. AEA and 2-AG are degraded by fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) enzymes, respectively. FAAH and MAGL enzymes are widely expressed in many tissues, including kidney. Recent works have depicted that AEA and 2-AG levels are associated with ischemia-reperfusion (IR) injury. In this study, we investigated the effects of MAGL inhibitor KML29 and FAAH inhibitor URB597 against kidney IR injury.

METHODS

The kidneys of the rats underwent ischemia for 45 min and then reperfusion for 24 h. KML29 and URB597 were administered intraperitoneally with kidney IR to two different treatment groups.

RESULTS

IR application increased serum blood urea nitrogen (BUN), creatinine (Cre), interleukin-18 (IL-18), neutrophil gelatinase-associated lipocalin (NGAL), and kidney injury molecule-1 (KIM-1) levels, while these parameters were decreased following KML29 and URB597 administration. KML29 and URB597 administration also reduced the increased toll-like receptor-4 (TRL-4), phosphorylated-NF-κB, phosphorylated-IκB-α, tumor necrosis factor alpha (TNF-α), interleukin-1beta (IL-1β), interleukin-6 (IL-6), caspase-3 levels and histopathological damage in kidney tissue.

CONCLUSIONS

Our results reveal that MAGL inhibitor KML29 and FAAH inhibitor URB597 have a protective effect on kidney IR injury by preventing apoptosis and inflammation. Inhibition of MAGL and FAAH may be a new therapeutic strategy to prevent kidney IR injury.

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.

The arachidonic acid and its metabolism pathway play important roles for Apostichopus japonicus infected by Vibrio splendens

Improving the immune ability and guiding healthy culture for sea cucumber by purposefully screening the significant differential metabolites when Apostichopus japonicus (A. japonicus) is infected by pathogens is important. In this study, 35 types of significant differential metabolites appeared when A. japonicus were infected by Vibrio splendens (VSI group) compared with the control A. japonicus group (CK group) by using liquid chromatography-mass spectrometry (LC-MS/MS)-based untargeted metabolomics. Based on that finding, the 10 types of key metabolic pathways were analyzed by MetPA. The "arachidonic acid (ARA) metabolism" pathway, which was screened by three elevated biomarkers: ARA, prostaglandin F2α and 2-arachidonoyl glycerol, had an important impact on immune stress in A. japonicus. Due to the similar changes in several metabolites in its metabolic pathway, the ARA metabolic pathway was selected for further study. The activities of ACP, AKP and lysozyme, which are important innate immune-related enzymes, the survival rates of A. japonicus infected with V. splendidus and the relative content of ARA in the body wall detected by GC-MS were all upregulated significantly by exogenous daily 0.60% and 1.09% ARA consumption over a short period of approximately 7 days. These results demonstrated that ARA and its metabolic pathway indeed played important roles in the immunity of A. japonicus infected by the pathogen. The findings also provide novel insights for the effects of metabolites in A. japonicum healthy culture.

The Critical Role of Cannabinoid Receptor 2 in URB602-Induced Protective Effects Against Renal Ischemia-Reperfusion Injury in the Rat

Renal ischemia-reperfusion injury (IRI) is a major cause of acute kidney injury (AKI) and even induces remote organ damage. Accumulating proofs demonstrates that the endocannabinoid system may provide a promising access for treatment strategy of renal IRI associated AKI. In the current study, using the established renal IRI model of rat, we tested the hypothesis that pretreatment of URB602, 30 min before renal IRI, alleviates kidney injury and relevant distant organ damage via limiting oxidative stress and inflammation. Using Western blot analysis and LC-MS/MS, renal IRI showed to increase the levels of 2-arachidonoylglycerol (2-AG) in kidneys as well as COX-2, PGE2, TXA2, and decrease N-arachidonoylethanolamine (anandamide, AEA); the expressions of renal cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2) were unchanged. The URB602 pretreatment in renal IRI, further enhanced renal 2-AG which is high affinity to both CB1 and CB2, and reduced renal COX-2 which is involved in the regulation of renal perfusion and inflammation. AM630 (CB2 antagonist) almost blocked all the antioxidant, anti-inflammatory and nephroprotective effects of URB602, whereas AM251 (CB1 antagonist) showed limited influence, and parecoxib (COX-2 inhibitor) slightly ameliorated renal function at the dose of 10 mg/kg. Taken together, our data indicate that URB602 acts as a reactive oxygen species scavenger and anti-inflammatory media in renal IRI mainly depending on the activation of CB2.

Pharmacological Properties, Therapeutic Potential and Molecular Mechanisms of JWH133, a CB2 Receptor-Selective Agonist

The endocannabinoid system has attracted attention as a pharmacological target for several pathological conditions. Cannabinoid (CB2)-selective agonists have been the focus of pharmacological studies because modulation of the CB2 receptor (CB2R) can be useful in the treatment of pain, inflammation, arthritis, addiction, and cancer among other possible therapeutic applications while circumventing CNS-related adverse effects. Increasing number of evidences from different independent preclinical studies have suggested new perspectives on the involvement of CB2R signaling in inflammation, infection and immunity, thus play important role in cancer, cardiovascular, renal, hepatic and metabolic diseases. JWH133 is a synthetic agonist with high CB2R selectivity and showed to exert CB2R mediated antioxidant, anti-inflammatory, anticancer, cardioprotective, hepatoprotective, gastroprotective, nephroprotective, and immunomodulatory activities. Cumulative evidences suggest that JWH133 protects against hepatic injury, renal injury, cardiotoxicity, fibrosis, rheumatoid arthritis, and cancer as well as against oxidative damage and inflammation, inhibits fibrosis and apoptosis, and acts as an immunosuppressant. This review provides a comprehensive overview of the polypharmacological properties and therapeutic potential of JWH133. This review also presents molecular mechanism and signaling pathways of JWH133 under various pathological conditions except neurological diseases. Based on the available data, this review proposes the possibilities of developing JWH133 as a promising therapeutic agent; however, further safety and toxicity studies in preclinical studies and clinical trials in humans are warranted.

Beneficial Outcomes of Omega-6 and Omega-3 Polyunsaturated Fatty Acids on Human Health: An Update for 2021

Oxidative stress and inflammation have been recognized as important contributors to the risk of chronic non-communicable diseases. Polyunsaturated fatty acids (PUFAs) may regulate the antioxidant signaling pathway and modulate inflammatory processes. They also influence hepatic lipid metabolism and physiological responses of other organs, including the heart. Longitudinal prospective cohort studies demonstrate that there is an association between moderate intake of the omega-6 PUFA linoleic acid and lower risk of cardiovascular diseases (CVDs), most likely as a result of lower blood cholesterol concentration. Current evidence suggests that increasing intake of arachidonic acid (up to 1500 mg/day) has no adverse effect on platelet aggregation and blood clotting, immune function and markers of inflammation, but may benefit muscle and cognitive performance. Many studies show that higher intakes of omega-3 PUFAs, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are associated with a lower incidence of chronic diseases characterized by elevated inflammation, including CVDs. This is because of the multiple molecular and cellular actions of EPA and DHA. Intervention trials using EPA + DHA indicate benefit on CVD mortality and a significant inverse linear dose-response relationship has been found between EPA + DHA intake and CVD outcomes. In addition to their antioxidant and anti-inflammatory roles, omega-3 fatty acids are considered to regulate platelet homeostasis and lower risk of thrombosis, which together indicate their potential use in COVID-19 therapy.

Juglanin protects against high fat diet-induced renal injury by suppressing inflammation and dyslipidemia via regulating NF-κB/HDAC3 signaling

Obesity is an important factor implicated in chronic kidney disease (CKD). Juglanin (Jug) is a natural compound extracted from the crude Polygonumaviculare, showing anti-inflammatory and anti-diabetic effects. However, whether Jug has protective effects against obesity-induced renal injury, little has been investigated. Herein, we attempted to explore the potential of Jug in mediating obesity-induced kidney disease in high fat diet (HFD)-challenged mice. Our results suggested that chronic HFD feeding markedly increased the body weights of mice compared to the ones fed with normal chow diet (NCD), along with significant glucose intolerance and insulin resistance. However, these metabolic disorders induced by HFD were effectively alleviated by Jug treatments in a dose-dependent manner. Moreover, HFD-challenged mice showed apparent histopathological changes in renal tissues with significant collagen accumulation, which were attenuated by Jug supplementation. In addition, Jug treatment decreased the expression levels of kidney injury molecule-1 (KIM-1), while increased nephrin and podocin expression levels in kidney of HFD-challenged mice, improving the renal dysfunction. Furthermore, HFD led to lipid deposition in kidney samples of mice by enhancing abnormal lipid metabolism. In addition, HFD promoted the releases of circulating pro-inflammatory cytokines, and enhanced the renal inflammation by activating nuclear factor-kappa B/histone deacetylase 3 (NF-κB/HDAC3) signaling. HFD-induced dyslipidemia and inflammation were considerably abrogated by Jug administration in mice. The protective effects of Jug against renal injury were confirmed in palmitate (PA)-stimulated HK2 cells in vitro mainly through suppressing the nuclear translocation of NF-κB and HDAC3, repressing inflammation and lipid accumulation eventually. Hence, Jug could ameliorate HFD-induced kidney injury mainly through blocking the NF-κB/HDAC3 nuclear translocation.

Modulation of Endocannabinoids by Caloric Restriction Is Conserved in Mice but Is Not Required for Protection from Acute Kidney Injury

Acute kidney injury (AKI) is a frequent and critical complication in the clinical setting. In rodents, AKI can be effectively prevented through caloric restriction (CR), which has also been shown to increase lifespan in many species. In Caenorhabditis elegans (C. elegans), longevity studies revealed that a marked CR-induced reduction of endocannabinoids may be a key mechanism. Thus, we hypothesized that regulation of endocannabinoids, particularly arachidonoyl ethanolamide (AEA), might also play a role in CR-mediated protection from renal ischemia-reperfusion injury (IRI) in mammals including humans. In male C57Bl6J mice, CR significantly reduced renal IRI and led to a significant decrease of AEA. Supplementation of AEA to near-normal serum concentrations by repetitive intraperitoneal administration in CR mice, however, did not abrogate the protective effect of CR. We also analyzed serum samples taken before and after CR from patients of three different pilot trials of dietary interventions. In contrast to mice and C. elegans, we detected an increase of AEA. We conclude that endocannabinoid levels in mice are modulated by CR, but CR-mediated renal protection does not depend on this effect. Moreover, our results indicate that modulation of endocannabinoids by CR in humans may differ fundamentally from the effects in animal models.

The protective effect of JZL184 on ovarian ischemia reperfusion injury and ovarian reserve in rats

AIM

Ovarian torsion is a gynecopathology that requires emergency surgery in women. However, ischemia reperfusion injury (IRI) occurs after treatment with detorsion. This study aimed to evaluate the effects of monoacylglycerol lipase inhibitor JZL184 on ovarian IRI and ovarian reserve.

METHODS

Forty-eight female Wistar albino rats were divided into six groups. Group 1: Sham, Group 2: Ischemia, Group 3: ischemia/reperfusion (IR), Group 4: IR + JZL184 4 mg/kg, Group 5: IR + JZL184 16 mg/kg, Group 6: IR + vehicle (dimethyl sulfoxide). Three hours of ischemia followed by 3 h of reperfusion. Two different doses of JZL184 (4 and 16 mg/kg) were administered intraperitoneally in Group 4 and 5, 30 min before reperfusion. Ovarian IRI and ovarian reserve were evaluated in serum and tissue by using histopathological and biochemical parameters.

RESULTS

Treatment with JZL184 was associated with a significant increase in ovarian 2-arachidonoylglycerol and improved serum anti-Mullerian hormone, İnhibin B, primordial follicle count, and ovarian histopathological damage score (p < 0.05). JZL184 treatment significantly decreased the level of malondialdehyde, and increased superoxide dismutase enzyme activity and glutathione (GSH) levels (p < 0.05). The increased phosphorile nuclear factor-κB (Phospho-NF-κB-p65), tumor necrosis factor alpha (TNF-α), interleukin-1beta (IL-1β), transforming growth factor beta 1 (TGF-β1), and TUNEL assay immunopositivity scores in ovarian I/R injury were decreased after treatment with JZL184 (p < 0.05).

CONCLUSIONS

JZL184 showed significant ameliorative effects on ovarian IRI and ovarian reserve caused by IR through acting as an antioxidant, anti-inflammatory, and antiapoptotic agent. Thus, JZL184 may be a novel therapeutic agent for ovarian IRI.

The nephrologist's guide to cannabis and cannabinoids

PURPOSE OF REVIEW

Cannabis (marijuana, weed, pot, ganja, Mary Jane) is the most commonly used federally illicit drug in the United States. The present review provides an overview of cannabis and cannabinoids with relevance to the practice of nephrology so that clinicians can best take care of patients.

RECENT FINDINGS

Cannabis may have medicinal benefits for treating symptoms of advanced chronic kidney disease (CKD) and end-stage renal disease including as a pain adjuvant potentially reducing the need for opioids. Cannabis does not seem to affect kidney function in healthy individuals. However, renal function should be closely monitored in those with CKD, the lowest effective dose should be used, and smoking should be avoided. Cannabis use may delay transplant candidate listing or contribute to ineligibility. Cannabidiol (CBD) has recently exploded in popularity. Although generally well tolerated, safe without significant side effects, and effective for a variety of neurological and psychiatric conditions, consumers have easy access to a wide range of unregulated CBD products, some with inaccurate labeling and false health claims. Importantly, CBD may raise tacrolimus levels.

SUMMARY

Patients and healthcare professionals have little guidance or evidence regarding the impact of cannabis use on people with kidney disease. This knowledge gap will remain as long as federal regulations remain prohibitively restrictive towards prospective research.

The protective effect of cannabinoid type 2 receptor activation on renal ischemia-reperfusion injury

Kidney ischemia reperfusion (IR) injury is an important health problem resulting in acute renal failure. After IR, the inflammatory and apoptotic process is triggered. The relation of Cannabinoid type 2 (CB2) receptor with inflammatory and apoptotic process has been determined. The CB2 receptor has been shown to be localized in glomeruli and tubules in human and rat kidney. Activation of CB2 receptor with JWH-133 has been shown to reduce apoptosis and inflammation. In this study, it was investigated whether CB2 activation with selective CB2 receptor agonist JWH-133 was protective against renal IR injury. Male Sprague-Dawley rats were divided into 5 groups (n = 45). Bilateral ischemia was treated to the IR group rat's kidneys for 45 min and then reperfusion was performed for 24 h. Three different doses of JWH-133 (0.2, 1 and 5 mg/kg) were administered to the treatment groups at the onset of ischemia. The JWH-133 application at three different doses decreased the glomerular and tubular damage. Additionally, in the renal tissue, nuclear factor-κB, tumour necrosis factor alpha, interleukin-1beta, and caspase-3 levels decreased immunohistochemically. Similarly, JWH-133 application decreased the serum tumour necrosis factor alpha, blood urea nitrogen, creatinine, kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, Cystatin C, interleukin-18, interleukin-1beta, interleukin-6, and interleukin-10 levels. We found that JWH-133 and CB2 receptor activation had a curative effect against kidney IR damage. JWH-133 may be a new therapeutic agent in preventing kidney IR damage.

Endocannabinoid System and the Kidneys: From Renal Physiology to Injury and Disease

Introduction: As the prevalence of kidney disease continues to rise worldwide, there is accumulating evidence that kidney injury and dysfunction, whether acute or chronic, is associated with major adverse outcomes, including mortality. Meanwhile, effective therapeutic options in the treatment of acute kidney injury (AKI) and chronic kidney disease (CKD) have been sparse. Many of the effective treatments that are routinely utilized for different pathologies in patients without kidney disease have failed to demonstrate efficacy in those with renal dysfunction. Hence, there is an urgent need for discovery of novel pathways that can be targeted for innovative and effective clinical therapies in renal disease states.

Discussion: There is now accumulating evidence that the endocannabinoid (EC) system plays a prominent role in normal renal homeostasis and function. In addition, numerous recent studies have described mechanisms through which alteration in the EC system can contribute to kidney damage and disease. These include a potential role for cannabinoid receptors in tubulo-glomerular damage and fibrosis, which are common features of AKI, interstitial nephritis, glomerulopathy, and other conditions leading to AKI and CKD.

Conclusion: These findings suggest that manipulating the EC system may be an effective therapeutic strategy for the treatment of kidney disease and injury. However, further mechanistic studies are needed to fully delineate the role of this system in various conditions affecting the kidneys. Furthermore, while most of the current literature is focused on the role of the EC system as a whole in renal pathophysiology, future studies will also need to clarify the contribution of each component of this system, including the EC mediators, in the pathogenesis of kidney disease and their potential role as part of a therapeutic strategy.

Connexin32 plays a crucial role in ROS-mediated endoplasmic reticulum stress apoptosis signaling pathway in ischemia reperfusion-induced acute kidney injury

BACKGROUND

Ischemia-reperfusion (I/R)-induced acute kidney injury (AKI) not only prolongs the length of hospital stay, but also seriously affects the patient's survival rate. Although our previous investigation has verified that reactive oxygen species (ROS) transferred through gap junction composed of connexin32 (Cx32) contributed to AKI, its underlying mechanisms were not fully understood and viable preventive or therapeutic regimens were still lacking. Among various mechanisms involved in organs I/R-induced injuries, endoplasmic reticulum stress (ERS)-related apoptosis is currently considered to be an important participant. Thus, in present study, we focused on the underlying mechanisms of I/R-induced AKI, and postulated that Cx32 mediated ROS/ERS/apoptosis signal pathway activation played an important part in I/R-induced AKI.

METHODS

We established renal I/R models with Cx32+/+ and Cx32-/- mice, which underwent double kidneys clamping and recanalization. ROS scavenger (N-acetylcysteine, NAC) and ERS inhibitors (4-phenyl butyric acid, 4-PBA, and tauroursodeoxycholic acid, TUDCA) were used to decrease the content of ROS and attenuate ERS activation, respectively.

RESULTS

Renal damage was progressively exacerbated in a time-dependent manner at the reperfusion stage, that was consistent with the alternation of ERS activation, including glucose regulated protein 78 (BiP/GRP78), X box-binding protein1, and C/EBP homologous protein expression. TUDCA or 4-PBA application attenuated I/R-induced ERS activation and protected against renal tubular epithelial cells apoptosis and renal damage. Cx32 deficiency decreased ROS generation and distribution between the neighboring cells, which attenuated I/R-induced ERS activation, and improved cell apoptosis and renal damage.

CONCLUSION

Cx32 mediated ROS/ERS/apoptosis signal pathway activation played an important part in I/R-induced AKI. Cx32 deficiency, ROS elimination, and ERS inhibition all could protect against I/R-induced AKI.

The role of cannabinoid signaling in acute and chronic kidney diseases

The endogenous cannabinoids anandamide and 2-arachidonoylglycerol bind to the cannabinoid receptors of type 1 and 2. These receptors are also the binding sites for exogenous, both natural and synthetic, cannabinoids that are used for recreation purposes. Until recently, cannabinoids and cannabinoid receptors have attracted little interest among nephrologists; however, a full endocannabinoid system (ECS) is present in the kidney and it has recently emerged as an important player in the pathogenesis of diabetic nephropathy, drug nephrotoxicity, and progressive chronic kidney disease. This newly established role of the ECS in the kidney might have therapeutic relevance, as pharmacological modulation of the ECS has renoprotective effects in experimental animals, raising hope for future potential applications in humans. In addition, over the last years, there has been a number of reported cases of acute kidney injury (AKI) associated with the use of synthetic cannabinoids that appear to have higher potency and rate of toxicity than natural Cannabis. This poorly recognized cause of renal injury should be considered in the differential diagnosis of AKI, particularly in young people. In this review we provide an overview of preclinical evidence indicating a role of the ECS in renal disease and discuss potential future therapeutic applications. Moreover, we give a critical update of synthetic cannabinoid-induced AKI.

Arachidonic acid: Physiological roles and potential health benefits - A review

It is time to shift the arachidonic acid (ARA) paradigm from a harm-generating molecule to its status of polyunsaturated fatty acid essential for normal health. ARA is an integral constituent of biological cell membrane, conferring it with fluidity and flexibility, so necessary for the function of all cells, especially in nervous system, skeletal muscle, and immune system. Arachidonic acid is obtained from food or by desaturation and chain elongation of the plant-rich essential fatty acid, linoleic acid. Free ARA modulates the function of ion channels, several receptors and enzymes, via activation as well as inhibition. That explains its fundamental role in the proper function of the brain and muscles and its protective potential against Schistosoma mansoni and S. haematobium infection and tumor initiation, development, and metastasis. Arachidonic acid in cell membranes undergoes reacylation/deacylation cycles, which keep the concentration of free ARA in cells at a very low level and limit ARA availability to oxidation. Metabolites derived from ARA oxidation do not initiate but contribute to inflammation and most importantly lead to the generation of mediators responsible for resolving inflammation and wound healing. Endocannabinoids are oxidation-independent ARA derivatives, critically important for brain reward signaling, motivational processes, emotion, stress responses, pain, and energy balance. Free ARA and metabolites promote and modulate type 2 immune responses, which are critically important in resistance to parasites and allergens insult, directly via action on eosinophils, basophils, and mast cells and indirectly by binding to specific receptors on innate lymphoid cells. In conclusion, the present review advocates the innumerable ARA roles and considerable importance for normal health.

Cannabinoids and the kidney: effects in health and disease

Consumption of cannabis and various related products (cannabinoids) for both medicinal and recreational use is gaining popularity. Furthermore, regulatory changes are fostering a cultural shift toward increasing liberalization of cannabis use, thereby increasing the likelihood of even larger numbers of individuals being exposed in the future. The two different types of receptors (CB1 and CB2) that are activated by the pharmacologically active ingredients of cannabis are found in numerous tissues, including the kidneys. Experimental studies suggest that stimulation of these receptors using pharmacologic agents or their naturally occurring ligands could have both deleterious and beneficial effects on the kidneys, depending on receptor distribution, type of renal insult, or the timing of the activation during acute or chronic states of kidney injury. To date, the mechanisms by which the CB1 or CB2 receptors are involved in the pathology of these renal conditions remain to be fully described. Furthermore, a better understanding of the impact of exocannabinoids and endocannabinoids on the renal system may lead to the development of new drugs to treat kidney disease and its complications. Given the increasing public health relevance of cannabis exposure, it is clear that more research is necessary to clarify the various physiological and pathophysiological effects of cannabis and related analogs on the kidney. This will help limit the deleterious effects of these substances while promoting their potential beneficial impact on renal function in various types of kidney diseases.