Modulation of Renal GLUT2 by the Cannabinoid-1 Receptor: Implications for the Treatment of Diabetic Nephropathy

Fufang Zhenzhu Tiaozhi (FTZ) capsule ameliorates diabetic kidney disease in mice via inhibiting the SGLT2/glycolysis pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Fufang Zhenzhu Tiaozhi (FTZ) capsule is a hospital preparation of a patented traditional Chinese medicine compound. FTZ has been clinically used for nearly 13 years in the treatment of diabetes and glycolipid metabolic diseases. With the significant benefits of SGLT2 inhibitor in patients with diabetic kidney disease (DKD), it provides a research avenue to explore the mechanism of FTZ in treating this disease based on glycolysis pathway.

AIM OF THE STUDY

To explore the pharmacological characteristics of FTZ in DKD mice and its impact on the glycolysis pathway.

MATERIALS AND METHODS

We induced a DKD model in C57BL/6 mice by injection of streptozotocin (STZ) combined with long-term high-fat diet. We administered three doses of FTZ for 12 weeks of treatment. Kidney function, blood lipid levels, glucose tolerance, and key glycolytic enzymes were evaluated. Renal pathological changes were observed using HE, MASSON, and PAS staining. The potential targets of the active ingredients of FTZ in the glycolysis pathway were predicted using network pharmacology and molecular docking. Validation was performed using immunohistochemistry and Western blotting.

RESULTS

FTZ effectively reduces blood glucose, total cholesterol, triglyceride, low density lipoprotein cholesterol, 24 h proteinuria, serum creatinine, blood urea nitrogen, and increases urinary glucose levels. Glucose tolerance and renal pathological changes were significantly improved by FTZ treatment. Pinusolidic acid, a component of FTZ, shows good binding affinity with three active pockets of SGLT2. WB and immunohistochemistry revealed that FTZ significantly inhibits the expression of SGLT2 and its glycolytic related proteins (GLUT2/PKM2/HK2). Hexokinase, pyruvate kinase, and lactate dehydrogenase in the kidney were also significantly inhibited by FTZ in a dose-dependent manner.

CONCLUSION

FTZ may alleviate the progression of DKD by inhibiting the activation of the SGLT2/glycolytic pathway. Our study provides new insights into the clinical application of FTZ in DKD.

Sema4D deficiency enhances glucose tolerance through GLUT2 retention in hepatocytes

BACKGROUND

The glucose transporter 2 (GLUT2) is constitutively expressed in pancreatic beta cells and hepatocytes of mice. It is the most important receptor in glucose-stimulated insulin release and hepatic glucose transport. The Sema4D is a signalin receptor on cell membranes. The correlation between Sema4D and GLUT2 has not been reported previously. We investigated whether knockdown of Sema4D could exert a hypoglycemic effect based on the increased GLUT2 expression in Sema4D -/- mice hepatocytes.

METHODS

The glucose tolerance test and insulin tolerance test in sema4D -/- and sema4D +/+ mice were compared before and after streptozotocin (STZ) injection; the expression of GLUT2 content on the membrane surface of both groups was verified by Western blot. Then, the levels of insulin and C-peptide in the serum of the two groups of mice after STZ injection were measured by ELISA; the differentially expressed mRNAs in the liver of the two groups of mice were analyzed by transcriptomic analysis; then the differences in the expression of GLUT2, glycogen, insulin and glucagon in the two groups of mice were compared by tissue section staining. Finally, metabolomics analysis was performed to analyze the metabolites differentially expressed in the two groups of mice.

KEY FINDINGS

First, Sema4D -/- male mice exhibited significantly greater glucose tolerance than wild-type mice in a hyperglycemic environment. Secondly, Sema4D -/- mice had more retained GLUT2 in liver membranes after STZ injection according to an immunofluorescence assay. After STZ injection, Sema4D -/- male mice did not exhibit fasting hyperinsulinemia like wild-type mice. Finally, analysis of metabolomic and immunohistochemical data also revealed that Sema4D -/- mice produce hypoglycemic effects by enhancing the pentose phosphate pathway, but not glycogen synthesis.

CONCLUSIONS

Thus, Sema4D may play an important role in the regulation of glucose homeostasis by affecting GLUT2 synthesis.

The pivotal role of glucose transporter 1 in diabetic kidney disease

Diabetes mellitus (DM) is a significant public health problem. Diabetic kidney disease (DKD) is the most common complication of DM, and its incidence has been increasing with the increasing prevalence of DM. Given the association between DKD and mortality in patients with DM, DKD is a significant burden on public health resources. Despite its significance in DM progression, the pathogenesis of DKD remains unclear. Aberrant glucose uptake by cells is an important pathophysiological mechanism underlying DKD renal injury. Glucose is transported across the bilayer cell membrane by a glucose transporter (GLUT) located on the cell membrane. Multiple GLUT proteins have been identified in the kidney, and GLUT1 is one of the most abundantly expressed isoforms. GLUT1 is a crucial regulator of intracellular glucose metabolism and plays a key pathological role in the phenotypic changes in DKD mesangial cells. In an attempt to understand the pathogenesis of DKD better, we here present a review of studies on the role of GLUT1 in the development and progression of DKD.

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.

Advancements in diabetic kidney disease management: integrating innovative therapies and targeted drug development

Diabetic kidney disease (DKD) is a leading cause of chronic kidney disease and affects approximately 40% of individuals with diabetes . Cases of DKD continue to rise globally as the prevalence of diabetes mellitus increases, with an estimated 415 million people living with diabetes in 2015 and a projected 642 million by 2040. DKD is associated with significant morbidity and mortality, representing 34% and 36% of all chronic kidney disease deaths in men and women, respectively. Common comorbidities including hypertension and ageing-related nephron loss further complicate disease diagnosis and progression. The progression of DKD involves several mechanisms including glomerular endothelial cell dysfunction, inflammation, and fibrosis. Targeting these mechanisms has formed the basis of several therapeutic agents. Renin-angiotensin-aldosterone system (RAAS) blockers, specifically angiotensin receptor blockers (ARBs), demonstrate significant reductions in macroalbuminuria. Sodium-glucose transporter type 2 (SGLT-2) inhibitors demonstrate kidney protection independent of diabetes control while also decreasing the incidence of cardiovascular events. Emerging agents including glucagon-like peptide 1 (GLP-1) agonists, anti-inflammatory agents like bardoxolone, and mineralocorticoid receptor antagonists show promise in mitigating DKD progression. Many novel therapies including monoclonal antibodies CSL346, lixudebart, and tozorakimab; mesenchymal stem/stromal cell infusion; and cannabinoid-1 receptor inverse agonism via INV-202 are currently in clinical trials and present opportunities for further drug development.

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.

The progression from mild to severe hyperglycemia coupled with insulin resistance causes mitochondrial dysfunction and alters the metabolic secretome of epithelial kidney cells

Diabetic nephropathy (DN) and insulin resistance (IR) in kidney cells are considered main causes for end-stage renal failure. However, it is unclear how IR affects early stages of the disease. Here, we investigate the impact of mild (11 mM) and severe (22 mM) hyperglycemia, with and without induced IR, on cellular metabolism and mitochondrial bioenergetics in a human kidney cell line (HK-2). IR in HK-2 cells was induced with palmitic acid and cellular cytotoxicity was studied. We evaluated the impact of mild and severe hyperglycemia with and without IR on the metabolic secretome of the cells, their live-cell mitochondria function, mitochondrial membrane potential, and mitochondrial complex activities. Furthermore, we measured fatty acid oxidation and lipid accumulation. Cells cultured under mild hyperglycemic conditions exhibited increased mitochondrial bioenergetic parameters, such as basal respiration, ATP-linked production, maximal respiration capacity, and spare respiration capacity. However, these parameters decreased when cells were cultured under higher glucose concentrations when IR was induced. Our data suggests that progression from mild to severe hyperglycemia induces a metabolic shift, where gluconeogenic amino acids play a crucial role in supplying the energy requirements of HK-2. To our knowledge, this is the first study to evaluate the progression from mild to severe hyperglycemia allied to IR in human kidney cells. This work highlights that this progression leads to mitochondrial dysfunction and alters the metabolic profile of kidney cells. These results identify possible targets for early intervention in DN.

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.

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.

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.

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.

Transcription factor c-Maf deletion improves streptozotocin-induced diabetic nephropathy by directly regulating Sglt2 and Glut2

The transcription factor c-Maf has been widely studied and has been reported to play a critical role in embryonic kidney development; however, the postnatal functions of c-Maf in adult kidneys remain unknown as c-Maf-null C57BL/6J mice exhibit embryonic lethality. In this study, we investigated the role of c-Maf in adult mouse kidneys by comparing the phenotypes of tamoxifen-inducible (TAM-inducible) c-Maf-knockout mice (c-Maffl/fl; CAG-Cre-ERTM mice named "c-MafΔTAM") with those of c-Maffl/fl control mice, 10 days after TAM injection [TAM(10d)]. In addition, we examined the effects of c-Maf deletion on diabetic conditions by injecting the mice with streptozotocin, 4 weeks before TAM injection. c-MafΔTAM mice displayed primary glycosuria caused by sodium-glucose cotransporter 2 (Sglt2) and glucose transporter 2 (Glut2) downregulation in the kidneys without diabetes, as well as morphological changes and life-threatening injuries in the kidneys on TAM(10d). Under diabetic conditions, c-Maf deletion promoted recovery from hyperglycemia and suppressed albuminuria and diabetic nephropathy by causing similar effects as did Sglt2 knockout and SGLT2 inhibitors. In addition to demonstrating the potentially unique gene regulation of c-Maf, these findings highlight the renoprotective effects of c-Maf deficiency under diabetic conditions and suggest that c-Maf could be a novel therapeutic target gene for treating diabetic nephropathy.

Hedgehog interacting protein activates sodium-glucose cotransporter 2 expression and promotes renal tubular epithelial cell senescence in a mouse model of type 1 diabetes

AIMS/HYPOTHESIS

Senescent renal tubular cells may be linked to diabetic kidney disease (DKD)-related tubulopathy. We studied mice with or without diabetes in which hedgehog interacting protein (HHIP) was present or specifically knocked out in renal tubules (Hhip^RT-KO), hypothesising that local deficiency of HHIP in the renal tubules would attenuate tubular cell senescence, thereby preventing DKD tubulopathy.

METHODS

Low-dose streptozotocin was employed to induce diabetes in both Hhip^RT-KO and control (Hhip^fl/fl) mice. Transgenic mice overexpressing Hhip in renal proximal tubular cells (RPTC) (Hhip^RPTC-Tg) were used for validation, and primary RPTCs and human RPTCs (HK2) were used for in vitro studies. Kidney morphology/function, tubular senescence and the relevant molecular measurements were assessed.

RESULTS

Compared with Hhip^fl/fl mice with diabetes, Hhip^RT-KO mice with diabetes displayed lower blood glucose levels, normalised GFR, ameliorated urinary albumin/creatinine ratio and less severe DKD, including tubulopathy. Sodium-glucose cotransporter 2 (SGLT2) expression was attenuated in RPTCs of Hhip^RT-KO mice with diabetes compared with Hhip^fl/fl mice with diabetes. In parallel, an increased tubular senescence-associated secretory phenotype involving release of inflammatory cytokines (IL-1β, IL-6 and monocyte chemoattractant protein-1) and activation of senescence markers (p16, p21, p53) in Hhip^fl/fl mice with diabetes was attenuated in Hhip^RT-KO mice with diabetes. In contrast, Hhip^RPTC-Tg mice had increased tubular senescence, which was inhibited by canagliflozin in primary RPTCs. In HK2 cells, HHIP overexpression or recombinant HHIP increased SGLT2 protein expression and promoted cellular senescence by targeting both ataxia-telangiectasia mutated and ataxia-telangiectasia and Rad3-related-mediated cell arrest.

CONCLUSIONS/INTERPRETATION

Tubular HHIP deficiency prevented DKD-related tubulopathy, possibly via the inhibition of SGLT2 expression and cellular senescence.

Hepatic targeting of the centrally active cannabinoid 1 receptor (CB1R) blocker rimonabant via PLGA nanoparticles for treating fatty liver disease and diabetes

Over-activation of the endocannabinoid/CB1R system is a hallmark feature of obesity and its related comorbidities, most notably type 2 diabetes (T2D), and non-alcoholic fatty liver disease (NAFLD). Although the use of drugs that widely block the CB1R was found to be highly effective in treating all metabolic abnormalities associated with obesity, they are no longer considered a valid therapeutic option due to their adverse neuropsychiatric side effects. Here, we describe a novel nanotechnology-based drug delivery system for repurposing the abandoned first-in-class global CB1R antagonist, rimonabant, by encapsulating it in polymeric nanoparticles (NPs) for effective hepatic targeting of CB1Rs, enabling effective treatment of NAFLD and T2D. Rimonabant-encapsulated NPs (Rimo-NPs) were mainly distributed in the liver, spleen, and kidney, and only negligible marginal levels of rimonabant were found in the brain of mice treated by iv/ip administration. In contrast to freely administered rimonabant treatment, no CNS-mediated behavioral activities were detected in animals treated with Rimo-NPs. Chronic treatment of diet-induced obese mice with Rimo-NPs resulted in reduced hepatic steatosis and liver injury as well as enhanced insulin sensitivity, which were associated with enhanced cellular uptake of the formulation into hepatocytes. Collectively, we successfully developed a method of encapsulating the centrally acting CB1R blocker in NPs with desired physicochemical properties. This novel drug delivery system allows hepatic targeting of rimonabant to restore the metabolic advantages of blocking CB1R in peripheral tissues, especially in the liver, without the negative CB1R-mediated neuropsychiatric side effects.

Kidney Proximal Tubule GLUT2-More than Meets the Eye

Tubulopathy plays a central role in the pathophysiology of diabetic kidney disease (DKD). Under diabetic conditions, the kidney proximal tubule cells (KPTCs) are exposed to an extensive amount of nutrients, most notably glucose; these nutrients deteriorate KPTCs function and promote the development and progression of DKD. Recently, the facilitative glucose transporter 2 (GLUT2) in KPTCs has emerged as a central regulator in the pathogenesis of DKD. This has been demonstrated by identifying its specific role in enhancing glucose reabsorption and glucotoxicity, and by deciphering its effect in regulating the expression of the sodium-glucose transporter 2 (SGLT2) in KPTCs. Moreover, reduction/deletion of KPTC-GLUT2 has been recently found to ameliorate DKD, raising the plausible idea of considering it as a therapeutic target against DKD. However, the underlying molecular mechanisms by which GLUT2 exerts its deleterious effects in KPTCs remain vague. Herein, we review the current findings on the proximal tubule GLUT2 biology and function under physiologic conditions, and its involvement in the pathophysiology of DKD. Furthermore, we shed new light on its cellular regulation during diabetic conditions.

Effects of the peripheral CB1 receptor antagonist JD5037 in mono— and polytherapy with the AMPK activator metformin in a monocrotaline-induced rat model of pulmonary hypertension

Pulmonary hypertension (PH) is a disease leading to increased pressure in the pulmonary artery and right heart failure. The adenosine monophosphate-activated protein kinase (AMPK) activator, metformin, has a protective effect against PH. CB₁ receptor blockade reduces the number of pathological alterations in experimental lung fibrosis. The current study evaluates the effect of the peripheral cannabinoid CB₁ receptor antagonist JD5037 in mono- and polytherapy with metformin in rat monocrotaline-induced mild PH. Animals received metformin (100 mg/kg), JD5037 (3 mg/kg), or a combination of both once daily for 21 days. Monocrotaline (60 mg/kg) increased right ventricular (RV) systolic pressure (RVSP), led to RV and lung hypertrophy and remodeling, and decreased oxygen saturation. Metformin partially restored the monocrotaline-induced effects, i.e., decreased RVSP, increased oxygen saturation, and counteracted cardiac fibrotic, hypertrophic, and inflammatory changes. JD5037 modified parameters related to inflammation and/or fibrosis. Only polytherapy with metformin and JD5037 improved Fulton’s index and coronary artery hypertrophy and tended to be more effective than monotherapy against alterations in RVSP, oxygen saturation and coronary artery tunica media vacuolization. In conclusion, monotherapy with JD5037 does not markedly influence the PH-related changes. However, polytherapy with metformin tends to be more efficient than any of these compounds alone.

The role of pancreas to improve hyperglycemia in STZ-induced diabetic rats by thiamine disulfide

Background

The present study investigated the effect of thiamine disulfide (TD) on the pancreas in terms of hyperglycemia improvement and insulin sensitivity increase in diabetic male rats. We also aimed to study the function of Pdx1 (pancreatic and duodenal homeobox 1) and Glut2 (glucose transporter 2) genes in pancreatic tissue.

Methods

Type 1 diabetes was induced through injection of 60 mg/kg streptozotocin (STZ). The diabetic rats were divided into four groups, namely diabetic control (DC), diabetic treated with thiamine disulfide (D-TD), diabetic treated with insulin (D-insulin), and diabetic treated with TD and insulin (D-insulin+TD). The non-diabetic (NDC) and diabetic groups received a normal diet (14 weeks). Blood glucose level and body weight were measured weekly; insulin tolerance test (ITT) and glucagon tolerance test (GTT) were performed in the last month of the study. The level of serum insulin and glucagon were measured monthly and a hyperglycemic clamp (Insulin Infusion rate (IIR)) was done for all the groups. Pancreas tissue was isolated so that Pdx1and Glut2 genes expression could be measured.

Results

We observed that TD therapy decreased blood glucose level, ITT, and serum glucagon levels in comparison with those of the DC group; it also increased serum insulin levels, IIR, and expression of Pdx1 and Glut2 genes in comparison with those of the DC group.

Conclusion

Administration of TD could improve hyperglycemia in type 1 diabetic animals through improved pancreas function. Therefore, not only does TD have a significant effect on controlling and reducing hyperglycemia in diabetes, but it also has the potential to decrease the dose of insulin administration.

Loss of function of renal Glut2 reverses hyperglycaemia and normalises body weight in mouse models of diabetes and obesity

AIMS/HYPOTHESIS

Renal GLUT2 is increased in diabetes, thereby enhancing glucose reabsorption and worsening hyperglycaemia. Here, we determined whether loss of Glut2 (also known as Slc2a2) specifically in the kidneys would reverse hyperglycaemia and normalise body weight in mouse models of diabetes and obesity.

METHODS

We used the tamoxifen-inducible CreERT2-Lox system in mice to knockout Glut2 specifically in the kidneys (Ks-Glut2 KO) to establish the contribution of renal GLUT2 to systemic glucose homeostasis in health and in insulin-dependent as well as non-insulin-dependent diabetes. We measured circulating glucose and insulin levels in response to OGTT or IVGTT under different experimental conditions in the Ks-Glut2 KO and their control mice. Moreover, we quantified urine glucose levels to explain the phenotype of the mice independently of insulin actions. We also used a transcription factor array to identify mechanisms underlying the crosstalk between renal GLUT2 and sodium-glucose cotransporter 2 (SGLT2).

RESULTS

The Ks-Glut2 KO mice exhibited improved glucose tolerance and massive glucosuria. Interestingly, this improvement in blood glucose control was eliminated when we knocked out Glut2 in the liver in addition to the kidneys, suggesting that the improvement is attributable to the lack of renal GLUT2. Remarkably, induction of renal Glut2 deficiency reversed hyperglycaemia and normalised body weight in mouse models of diabetes and obesity. Longitudinal monitoring of renal glucose transporters revealed that Sglt2 (also known as Slc5a2) expression was almost abolished 3 weeks after inducing renal Glut2 deficiency. To identify a molecular basis for this crosstalk, we screened for renal transcription factors that were downregulated in the Ks-Glut2 KO mice. Hnf1α (also known as Hnf1a) was among the genes most downregulated and its recovery restored Sglt2 expression in primary renal proximal tubular cells isolated from the Ks-Glut2 KO mice.

CONCLUSIONS/INTERPRETATION

Altogether, these results demonstrate a novel crosstalk between renal GLUT2 and SGLT2 in regulating systemic glucose homeostasis via glucose reabsorption. Our findings also indicate that inhibiting renal GLUT2 is a potential therapy for diabetes and obesity.

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.

Understanding the Mechanism of Dysglycemia in a Fanconi-Bickel Syndrome Patient

Fanconi-Bickel Syndrome (FBS) is a rare disorder of carbohydrate metabolism that is characterized mainly by the accumulation of glycogen in the liver and kidney. It is inherited as an autosomal recessive disorder caused by mutations in the SLC2A2 gene, which encodes for GLUT2. Patients with FBS have dysglycemia but the molecular mechanisms of dysglycemia are still not clearly understood. Therefore, we aimed to understand the underlying molecular mechanisms of dysglycemia in a patient with FBS. Genomic DNA was isolated from a peripheral blood sample and analyzed by whole genome and Sanger sequencing. CRISPR-Cas9 was used to introduce a mutation that mimics the patient's mutation in a human kidney cell line expressing GLUT2 (HEK293T). Mutant cells were used for molecular analysis to investigate the effects of the mutation on the expression and function of GLUT2, as well as the expression of other genes implicated in dysglycemia. The patient was found to have a homozygous nonsense mutation (c.901C>T, R301X) in the SLC2A2 gene. CRISPR-Cas9 successfully mimicked the patient's mutation in HEK293T cells. The mutant cells showed overexpression of a dysfunctional GLUT2 protein, resulting in reduced glucose release activity and enhanced intracellular glucose accumulation. In addition, other glucose transporters (SGLT1 and SGLT2 in the kidney) were found to be induced in the mutant cells. These findings suggest the last loops (loops 9-12) of GLUT2 are essential for glucose transport activity and indicate that GLUT2 dysfunction is associated with dysglycemia in FBS.

Renal Tubular Handling of Glucose and Fructose in Health and Disease

The proximal tubule of the kidney is programmed to reabsorb all filtered glucose and fructose. Glucose is taken up by apical sodium-glucose cotransporters SGLT2 and SGLT1 whereas SGLT5 and potentially SGLT4 and GLUT5 have been implicated in apical fructose uptake. The glucose taken up by the proximal tubule is typically not metabolized but leaves via the basolateral facilitative glucose transporter GLUT2 and is returned to the systemic circulation or used as an energy source by distal tubular segments after basolateral uptake via GLUT1. The proximal tubule generates new glucose in metabolic acidosis and the postabsorptive phase, and fructose serves as an important substrate. In fact, under physiological conditions and intake, fructose taken up by proximal tubules is primarily utilized for gluconeogenesis. In the diabetic kidney, glucose is retained and gluconeogenesis enhanced, the latter in part driven by fructose. This is maladaptive as it sustains hyperglycemia. Moreover, renal glucose retention is coupled to sodium retention through SGLT2 and SGLT1, which induces secondary deleterious effects. SGLT2 inhibitors are new anti-hyperglycemic drugs that can protect the kidneys and heart from failing independent of kidney function and diabetes. Dietary excess of fructose also induces tubular injury. This can be magnified by kidney formation of fructose under pathological conditions. Fructose metabolism is linked to urate formation, which partially accounts for fructose-induced tubular injury, inflammation, and hemodynamic alterations. Fructose metabolism favors glycolysis over mitochondrial respiration as urate suppresses aconitase in the tricarboxylic acid cycle, and has been linked to potentially detrimental aerobic glycolysis (Warburg effect). © 2022 American Physiological Society. Compr Physiol 12:2995-3044, 2022.

Functional characterization of Clonorchis sinensis sodium-bile acid co-transporter (CsSBAT) as a steroid sulfate transporter

Clonorchis sinensis (Cs) is a common trematode in Asian countries. Infection by Cs can result in many clinical symptoms. Here, a cDNA encoding a Cs apical sodium-dependent bile acid transporter (CsSBAT) was isolated from a Cs cDNA library, and functional characterization was performed using Xenopus laevis oocyte expression system. When expressed in Xenopus laevis oocytes, CsSBAT mediated the transport of radiolabeled estrone sulfate and dehydroepiandrosterone sulfate. No trans-uptake of carnitine, estradiol 17 β-D glucuronide, prostaglandin E₂, p-aminohippuric acid, α-ketoglutaric acid, and tetraethylammonium was observed. CsSBAT-mediated estrone sulfate uptake was in a time- and sodium-dependent manner. CsSBAT showed no exchange properties in efflux experiments. Concentration-dependent results showed saturable kinetics consistent with the Michaelis-Menten equation. Nonlinear regression analyses yielded a Km value of 0.3 ± 0.04 μM for [³H]estrone sulfate. CsSBAT-mediated estrone sulfate uptake was strongly inhibited by sulfate conjugates but not glucuronide conjugates. These findings contribute to our understanding of CsSBAT transport properties and the cascade of estrogen metabolite movement in Cs.

Mitochondria in Diabetic Kidney Disease

Diabetic kidney disease (DKD) is the leading cause of end stage renal disease (ESRD) in the USA. The pathogenesis of DKD is multifactorial and involves activation of multiple signaling pathways with merging outcomes including thickening of the basement membrane, podocyte loss, mesangial expansion, tubular atrophy, and interstitial inflammation and fibrosis. The glomerulo-tubular balance and tubule-glomerular feedback support an increased glomerular filtration and tubular reabsorption, with the latter relying heavily on ATP and increasing the energy demand. There is evidence that alterations in mitochondrial bioenergetics in kidney cells lead to these pathologic changes and contribute to the progression of DKD towards ESRD. This review will focus on the dialogue between alterations in bioenergetics in glomerular and tubular cells and its role in the development of DKD. Alterations in energy substrate selection, electron transport chain, ATP generation, oxidative stress, redox status, protein posttranslational modifications, mitochondrial dynamics, and quality control will be discussed. Understanding the role of bioenergetics in the progression of diabetic DKD may provide novel therapeutic approaches to delay its progression to ESRD.

The Potential Use of Cannabis in Tissue Fibrosis

Fibrosis is a condition characterized by thickening or/and scarring of various tissues. Fibrosis may develop in almost all tissues and organs, and it may be one of the leading causes of morbidity and mortality. It provokes excessive scarring that excels the usual wound healing response to trauma in numerous organs. Currently, very little can be done to prevent tissue fibrosis, and it is almost impossible to reverse it. Anti-inflammatory and immunosuppressive drugs are among the few treatments that may be efficient in preventing fibrosis. Numerous publications suggest that cannabinoids and extracts of Cannabis sativa have potent anti-inflammatory and anti-fibrogenic properties. In this review, we describe the types and mechanisms of fibrosis in various tissues and discuss various strategies for prevention and dealing with tissue fibrosis. We further introduce cannabinoids and their potential for the prevention and treatment of fibrosis, and therefore for extending healthy lifespan.

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.

Comprehensive analysis of diabetic nephropathy expression profile based on weighted gene co-expression network analysis algorithm

Background

Diabetic nephropathy (DN) is the major complication of diabetes mellitus, and leading cause of end-stage renal disease. The underlying molecular mechanism of DN is not yet completely clear. The aim of this study was to analyze a DN microarray dataset using weighted gene co-expression network analysis (WGCNA) algorithm for better understanding of DN pathogenesis and exploring key genes in the disease progression.

Methods

The identified differentially expressed genes (DEGs) in DN dataset GSE47183 were introduced to WGCNA algorithm to construct co-expression modules. STRING database was used for construction of Protein-protein interaction (PPI) networks of the genes in all modules and the hub genes were identified considering both the degree centrality in the PPI networks and the ranked lists of weighted networks. Gene ontology and Reactome pathway enrichment analyses were performed on each module to understand their involvement in the biological processes and pathways. Following validation of the hub genes in another DN dataset (GSE96804), their up-stream regulators, including microRNAs and transcription factors were predicted and a regulatory network comprising of all these molecules was constructed.

Results

After normalization and analysis of the dataset, 2475 significant DEGs were identified and clustered into six different co-expression modules by WGCNA algorithm. Then, DEGs of each module were subjected to functional enrichment analyses and PPI network constructions. Metabolic processes, cell cycle control, and apoptosis were among the top enriched terms. In the next step, 23 hub genes were identified among the modules in genes and five of them, including FN1, SLC2A2, FABP1, EHHADH and PIPOX were validated in another DN dataset. In the regulatory network, FN1 was the most affected hub gene and mir-27a and REAL were recognized as two main upstream-regulators of the hub genes.

Conclusions

The identified hub genes from the hearts of co-expression modules could widen our understanding of the DN development and might be of targets of future investigations, exploring their therapeutic potentials for treatment of this complicated disease.

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.

Carnosine alleviates diabetic nephropathy by targeting GNMT, a key enzyme mediating renal inflammation and fibrosis

Diabetic nephropathy (DN) is a common microvascular complication of diabetes and the main cause of end-stage nephropathy (ESRD). Inflammation and fibrosis play key roles in the development and progression of diabetic nephropathy. By using in vivo and in vitro DN models, our laboratory has identified the protective role of carnosine (CAR) on renal tubules. Our results showed that carnosine restored the onset and clinical symptoms as well as renal tubular injury in DN. Furthermore, carnosine decreased kidney inflammation and fibrosis in DN mice. These results were consistent with high glucose (HG)-treated mice tubular epithelial cells (MTECs). Using web-prediction algorithms, cellular thermal shift assay (CETSA) and molecular docking, we identified glycine N-methyltransferase (GNMT) as a carnosine target. Importantly, we found that GNMT, a multiple functional protein that regulates the cellular pool of methyl groups by controlling the ratio of S-adenosylmethionine (SAM) to S-adenosylhomocysteine (SAH), was down-regulated significantly in the serum of Type 1 DM patients and renal tissues of DN mice. Moreover, using cultured TECs, we confirmed that the increased GNMT expression by transient transfection mimicked the protective role of carnosine in reducing inflammation and fibrosis. Conversely, the inhibition of GNMT expression abolished the protective effects of carnosine. In conclusion, carnosine might serve as a promising therapeutic agent for DN and GNMT might be a potential therapeutic target for DN.

Pathogenesis of diabesity-induced kidney disease: role of kidney nutrient sensing

Diabetes kidney disease (DKD) is a major healthcare problem associated with increased risk for developing end-stage kidney disease and high mortality. It is widely accepted that DKD is primarily a glomerular disease. Recent findings however suggest that kidney proximal tubule cells (KPTCs) may play a central role in the pathophysiology of DKD. In diabetes and obesity, KPTCs are exposed to nutrient overload, including glucose, free-fatty acids and amino acids, which dysregulate nutrient and energy sensing by mechanistic target of rapamycin complex 1 and AMP-activated protein kinase, with subsequent induction of tubular injury, inflammation, and fibrosis. Pharmacological treatments that modulate nutrient sensing and signaling in KPTCs, including cannabinoid-1 receptor antagonists and sodium glucose transporter 2 inhibitors, exert robust kidney protective effects. Shedding light on how nutrients are sensed and metabolized in KPTCs and in other kidney domains, and on their effects on signal transduction pathways that mediate kidney injury, is important for understanding the pathophysiology of DKD and for the development of novel therapeutic approaches in DKD and probably also in other forms of kidney disease.

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.

Geniposide Improves Diabetic Nephropathy by Enhancing ULK1-Mediated Autophagy and Reducing Oxidative Stress through AMPK Activation

Diabetic nephropathy (DN) is a common pathological feature in patients with diabetes and the leading cause of end-stage renal disease. Although several pharmacological agents have been developed, the management of DN remains challenging. Geniposide, a natural compound has been reported for anti-inflammatory and anti-diabetic effects; however, its role in DN remains poorly understood. This study investigated the protective effects of geniposide on DN and its underlying mechanisms. We used a C57BL/6 mouse model of DN in combination with a high-fat diet and streptozotocin after unilateral nephrectomy and treated with geniposide by oral gavage for 5 weeks. Geniposide effectively improves DN-induced renal structural and functional abnormalities by reducing albuminuria, podocyte loss, glomerular and tubular injury, renal inflammation and interstitial fibrosis. These changes induced by geniposide were associated with an increase of AMPK activity to enhance ULK1-mediated autophagy response and a decrease of AKT activity to block oxidative stress, inflammation and fibrosis in diabetic kidney. In addition, geniposide increased the activities of PKA and GSK3β, possibly modulating AMPK and AKT pathways, efficiently improving renal dysfunction and ameliorating the progression of DN. Conclusively, geniposide enhances ULK1-mediated autophagy and reduces oxidative stress, inflammation and fibrosis, suggesting geniposide as a promising treatment for DN.

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.

Cannabinoid receptor type 2 promotes kidney fibrosis through orchestrating β-catenin signaling

The endocannabinoid system has multiple effects. Through interacting with cannabinoid receptor type 1 and type 2, this system can greatly affect disease progression. Previously, we showed that activated cannabinoid receptor type 2 (CB2) mediated kidney fibrosis. However, the underlying mechanisms remain underdetermined. Here, we report that CB2 was upregulated predominantly in kidney tubular epithelial cells in unilateral urinary obstruction and ischemia-reperfusion injury models in mice, and in patients with a variety of kidney diseases. CB2 expression was closely correlated with the progression of kidney fibrosis and accompanied by the activation of β-catenin. Furthermore, CB2 induced the formation of a β-arrestin 1/Src/β-catenin complex, which further triggered the nuclear translocation of β-catenin and caused fibrotic injury. Incubation with XL-001, an inverse agonist to CB2, or knockdown of β-arrestin 1 inhibited CB2-triggered activation of β-catenin and fibrotic injury. Notably, CB2 potentiated Wnt1-induced β-arrestin 1/β-catenin activation and augmented the pathogenesis of kidney fibrosis in mice with unilateral ischemia-reperfusion injury or folic acid-induced nephropathy. Knockdown of β-arrestin 1 inhibited the CB2 agonist AM1241-induced β-catenin activation and kidney fibrosis. By promoter sequence analysis, putative transcription factor binding sites for T-cell factor/lymphoid enhancer factor were found in the promoter regions of the CB2 gene regardless of the species. Overexpression of β-catenin induced the binding of T-cell factor/lymphoid enhancer factor-1 to these sites, promoted the expression of CB2, β-arrestin 1, and the proto-oncogene Src, and triggered their accumulation. Thus, the CB2/β-catenin pathway appears to create a reciprocal activation feedback loop that plays a central role in the pathogenesis of kidney fibrosis.

Modulation of Calcium Homeostasis May Be Associated with Susceptibility to Renal Cell Carcinoma in Diabetic Nephropathy Rats

Introduction

Clinical studies have indicated a relationship between diabetic nephropathy (DN) and the incidence and prevalence of renal cell carcinoma (RCC). However, the mechanism linking diabetic nephropathy and renal cell carcinoma has not yet to be identified.

Methods

In this study, a total of 42 male Sprague Dawley (SD) rats were randomly assigned to a DN group (n=35) and a control group (n=7). All animals in the DN group were unilaterally nephrectomized and treated with streptozotocin with the development of blood glucose levels >16.7mmol/L and dominant proteinuria and were compared to controls without such changes. Histopathologic alterations in the kidneys were examined by HE staining and Ki-67 immunohistochemistry. Differentially expressed genes were identified and validated by RNA-seq and PCR.

Results

As the results, except for two rats that failed to develop the DN model and were excluded from the analysis, 33 rats in the DN group with overt signs of DN demonstrated significantly higher food and water intake, urine production, and urine protein and urinary protein/creatinine ratio than controls. Overall, 15.2% (n=5/33) of DN animals developed RCC while none tumors were observed in the control group (n=0/7). RNA-seq analysis in these animals indicated different TRPV5 gene expression and calcium pathway expression in DN animals with developing tumors, when compared with animals with no obvious tumors. In addition, DN animals diagnosed with RCC showed increased expression of GLUT2 and c-met, when compared to controls and DN animals without tumors.

Discussion

In conclusion, the disordered calcium metabolism, especially disturbed TRPV5 mediated Ca²⁺ signal, may have been related to the development of RCC in DN rats. Further studies related to the detailed mechanism are still needed.

Novel therapeutic agents for the treatment of diabetic kidney disease

INTRODUCTION

Diabetic kidney disease (DKD) involves multifaceted pathophysiology which increases the risk of cardiorenal events and mortality. Conventional therapy is limited to renin-angiotensin aldosterone system inhibition and management of hyperglycemia and hypertension. Recent clinical trials have demonstrated promising nephroprotective effects of antihyperglycemic agents thus modifying guideline treatment recommendations for type 2 diabetic patients with chronic kidney disease.

AREAS OF COVERED

Relevant studies and clinical trials were searched via PubMed and clinicaltrials.gov through August 2020. Authors offer an update on clinical evidence regarding nephroprotective effects and side effects of sodium-glucose-cotransporter-2 (SGLT2) inhibitors, glucagon-like-peptide-1 (GLP1) agonists and dipeptidylpeptidase-4 (DPP4) inhibitors. They discuss the potential benefits of novel therapy targeting DKD pathogenic processes including inflammation, oxidative stress, fibrosis, and vasoconstriction shown in early phases of clinical trials and offer an opinion on key challenges and directions for future progress.

EXPERT OPINION

SGLT2 inhibitors are the most promising agents for DKD and improving cardiorenal outcomes. Mineralocorticoid-receptor antagonists and janus kinase inhibitors are also promising investigational therapies that target oxidative stress, nitric oxide synthesis, and inflammation. Novel therapeutic targets and the identification of clinically useful biomarkers may provide future therapies that detect early stages of DKD enabling a slower kidney function decline.

Glucose transporters in the kidney in health and disease

The kidneys filter large amounts of glucose. To prevent the loss of this valuable fuel, the tubular system of the kidney, particularly the proximal tubule, has been programmed to reabsorb all filtered glucose. The machinery involves the sodium-glucose cotransporters SGLT2 and SGLT1 on the apical membrane and the facilitative glucose transporter GLUT2 on the basolateral membrane. The proximal tubule also generates new glucose, particularly in the post-absorptive phase but also to enhance bicarbonate formation and maintain acid-base balance. The glucose reabsorbed or formed by the proximal tubule is primarily taken up into peritubular capillaries and returned to the systemic circulation or provided as an energy source to further distal tubular segments that take up glucose by basolateral GLUT1. Recent studies provided insights on the coordination of renal glucose reabsorption, formation, and usage. Moreover, a better understanding of renal glucose transport in disease states is emerging. This includes the kidney in diabetes mellitus, when renal glucose retention becomes maladaptive and contributes to hyperglycemia. Furthermore, enhanced glucose reabsorption is coupled to sodium retention through the sodium-glucose cotransporter SGLT2, which induces secondary deleterious effects. As a consequence, SGLT2 inhibitors are new anti-hyperglycemic drugs that can protect the kidneys and heart from failing. Recent studies discovered unique roles for SGLT1 with implications in acute kidney injury and glucose sensing at the macula densa. This review discusses established and emerging concepts of renal glucose transport, and outlines the need for a better understanding of renal glucose handling in health and disease.

Endothelial cells secreted endothelin-1 augments diabetic nephropathy via inducing extracellular matrix accumulation of mesangial cells in ETBR-/- mice

Endothelin B receptor (ETBR) deficiency may contribute to the progression of diabetic nephropathy (DN) in a streptozotocin (STZ) model, but the underlying mechanism is not fully revealed. In this study, STZ-diabetic ETBR^-/- mice was characterized by increased serum creatinine and urinary albumin, enhanced glomerulosclerosis, and upregulated ET-1 expression compared with STZ-diabetic WT mice. In vitro, HG conditioned media (CM) of ETBR^-/- GENs promoted mesangial cell proliferation and upregulated ECM-related proteins, and ET-1 knockout in GENs or inhibition of ET-1/ETAR in mesangial cell suppressed mesangial cell proliferation and collagen IV formation. In addition, ET-1 was over-expressed in ETBR^-/- GENs and was regulated by NF-kapapB pathway. ET-1/ETBR suppressed NF-kappaB to modulate ET-1 in GENs. Furthermore, ET-1/ETAR promoted RhoA/ROCK pathway in mesangial cells, and accelerated mesangial cell proliferation and ECM accumulation. Finally, in vivo experiments proved inhibition of NF-kappaB pathway ameliorated DN in ETBR^-/- mice. These results suggest that in HG-exposed ETBR^-/- GENs, suppression of ET-1 binding to ETBR activated NF-kappaB pathway, thus to secrete large amount of ET-1. Due to the communication between GENs and mesangial cells in diabetes, ET-1 binding to ETAR in mesangial cell promoted RhoA/ROCK pathway, thus to accelerate mesangial cell proliferation and ECM accumulation.

Influence of Cannabinoid Receptor Deficiency on Parameters Involved in Blood Glucose Regulation in Mice

Cannabinoids are known to influence hormone secretion of pancreatic islets via G protein-coupled cannabinoid receptor type 1 and 2 (CB₁ and CB₂). The present study was designed to further investigate the impact of cannabinoid receptors on the parameters involved in insulin secretion and blood glucose recognition. To this end, CB₁ and CB₂ receptor knockout mice (10–12 week old, both sexes) were characterised at basal state and compared to wild-type mice. The elimination of cannabinoid receptor signalling resulted in alterations of blood glucose concentrations, body weights and insulin levels. Changes were dependent on the deleted receptor type and on the sex. Analyses at mRNA and protein levels provided evidence for the impact of cannabinoid receptor deficiency on the glucose sensing apparatus in the pancreas. Both receptor knockout mouse lines showed decreased mRNA and protein amounts of glucose transporters Glut1 and Glut2, combined with alterations in immunostaining. In addition, pancreatic glucokinase expression was elevated and immunohistochemical labelling was modified in the pancreatic islets. Taken together, CB₁ and CB₂ signalling pathways seem to influence glucose sensing in β-cells by affecting glucose transporters and glucokinase. These alterations were more pronounced in CB₂ knockout mice, resulting in higher blood glucose and lower plasma insulin levels.

Anti-obesity therapy with peripheral CB1 blockers: from promise to safe(?) practice

Pharmacological blockers of the cannabinoid receptor type-1 (CB1) have been considered for a long time as the holy grail of obesity pharmacotherapy. These agents were hastily released in the clinical setting, due to their clear-cut therapeutic efficacy. However, the first generation of these drugs, which were able to target both the brain and peripheral tissues, had serious neuropsychiatric effects, leading authorities to ban their clinical use. New peripherally restricted CB1 blockers, characterized by low brain penetrance, have been developed over the past 10 years. In preclinical studies, these molecules seem to overcome the neuropsychiatric negative effects previously observed with brain-penetrant CB1 inhibitors, while retaining or even outperforming their efficacy. The mechanisms of action of these peripherally restricted compounds are only beginning to emerge, and a balanced discussion of the risk/benefits ratio associated to their possible clinical use is urgently needed, in order to avoid repeating past mistakes. Here, we will critically discuss the advantages and the possible hidden threats associated with the use of peripheral CB1 blockers for the pharmacotherapy of obesity and its associated metabolic complications. We will address whether this novel pharmacological approach might 'compete' with current pharmacotherapies for obesity and diabetes, while also conceptualizing future CB1-based pharmacological trends that may significantly lower the risk/benefits ratio associated with the use of these drugs.

A Guide to Targeting the Endocannabinoid System in Drug Design

The endocannabinoid system (ECS) is one of the most crucial systems in the human organism, exhibiting multi-purpose regulatory character. It is engaged in a vast array of physiological processes, including nociception, mood regulation, cognitive functions, neurogenesis and neuroprotection, appetite, lipid metabolism, as well as cell growth and proliferation. Thus, ECS proteins, including cannabinoid receptors and their endogenous ligands’ synthesizing and degrading enzymes, are promising therapeutic targets. Their modulation has been employed in or extensively studied as a treatment of multiple diseases. However, due to a complex nature of ECS and its crosstalk with other biological systems, the development of novel drugs turned out to be a challenging task. In this review, we summarize potential therapeutic applications for ECS-targeting drugs, especially focusing on promising synthetic compounds and preclinical studies. We put emphasis on modulation of specific proteins of ECS in different pathophysiological areas. In addition, we stress possible difficulties and risks and highlight proposed solutions. By presenting this review, we point out information pivotal in the spotlight of ECS-targeting drug design, as well as provide an overview of the current state of knowledge on ECS-related pharmacodynamics and show possible directions for needed research.

Pathophysiologic mechanisms in diabetic kidney disease: A focus on current and future therapeutic targets

Diabetic kidney disease (DKD) is the primary cause of chronic kidney disease around the globe and is one of the main complications in patients with type 1 and 2 diabetes. The standard treatment for DKD is drugs controlling hyperglycemia and high blood pressure. Renin angiotensin aldosterone system blockade and sodium glucose cotransporter 2 (SGLT2) inhibition have yielded promising results in DKD, but many diabetic patients on such treatments nevertheless continue to develop DKD, leading to kidney failure and cardiovascular comorbidities. New therapeutic options are urgently required. We review here the promising therapeutic avenues based on insights into the mechanisms of DKD that have recently emerged, including mineralocorticoid receptor antagonists, SGLT2 inhibitors, glucagon-like peptide-1 receptor agonist, endothelin receptor A inhibition, anti-inflammatory agents, autophagy activators and epigenetic remodelling. The involvement of several molecular mechanisms in DKD pathogenesis, together with the genetic and epigenetic variability of this condition, makes it difficult to target this heterogeneous patient population with a single drug. Personalized medicine, taking into account the genetic and mechanistic variability, may therefore improve renal and cardiovascular protection in diabetic patients with DKD.

The tubular hypothesis of nephron filtration and diabetic kidney disease

Kidney size and glomerular filtration rate (GFR) often increase with the onset of diabetes, and elevated GFR is a risk factor for the development of diabetic kidney disease. Hyperfiltration mainly occurs in response to signals passed from the tubule to the glomerulus: high levels of glucose in the glomerular filtrate drive increased reabsorption of glucose and sodium by the sodium-glucose cotransporters SGLT2 and SGLT1 in the proximal tubule. Passive reabsorption of chloride and water also increases. The overall capacity for proximal reabsorption is augmented by growth of the proximal tubule, which (alongside sodium-glucose cotransport) further limits urinary glucose loss. Hyperreabsorption of sodium and chloride induces tubuloglomerular feedback from the macula densa to increase GFR. In addition, sodium-glucose cotransport by SGLT1 on macula densa cells triggers the production of nitric oxide, which also contributes to glomerular hyperfiltration. Although hyperfiltration restores sodium and chloride excretion it imposes added physical stress on the filtration barrier and increases the oxygen demand to drive reabsorption. Tubular growth is associated with the development of a senescence-like molecular signature that sets the stage for inflammation and fibrosis. SGLT2 inhibitors attenuate the proximal reabsorption of sodium and glucose, normalize tubuloglomerular feedback signals and mitigate hyperfiltration. This tubule-centred model of diabetic kidney physiology predicts the salutary effect of SGLT2 inhibitors on hard renal outcomes, as shown in large-scale clinical trials.

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.

Advanced Oxidation Protein Products Promote Lipotoxicity and Tubulointerstitial Fibrosis via CD36/β-Catenin Pathway in Diabetic Nephropathy

Aims: Diabetic nephropathy (DN) is the principal cause of mortality and morbidity in diabetic patients, the progression of which correlates best with tubulointerstitial fibrosis (TIF). Advanced oxidation protein products (AOPPs) have been detected in patients with chronic renal failure, causing injuries to proximal tubular epithelial cells. CD36, a known receptor for AOPP, is an important modulator of lipid homeostasis, predisposing to renal tubular damage. However, whether AOPPs induce lipotoxicity via the CD36 receptor pathway remains unknown. Herein, we tested the hypothesis that AOPPs accumulation in diabetes incurs lipotoxicity, causing renal TIF via the CD36 signaling pathway. Results: In DN patients and diabetic mice in vivo, AOPPs overload induces lipogenesis (upregulation of CD36 and sterol regulatory element-binding protein 1), fibrosis (upregulation of Fibronectin), and renal function decline (increased serum creatinine and N-acetyl-β-d-glucosaminidase, decreased estimated glomerular filtration rate). In HK-2 cells in vitro, high glucose stimulated AOPPs-induced lipotoxicity, apoptosis, and fibrosis via the CD36 receptor pathway. In addition, apocynin abrogated AOPPs-induced lipid accumulation and CD36 inhibition significantly mitigated AOPPs-induced mitochondrial injuries, lipotoxicity, and renal fibrosis. Further, we provide mechanistic evidence that AOPPs overload induces the enrichment of β-catenin binding the CD36 promoter region. Innovation and Conclusion: Our data reveal a major role of AOPPs in triggering lipotoxicity and fibrosis via CD36-dependent Wnt/β-catenin activation, providing new evidence for understanding the role of lipid accumulation in DN.

The cannabinoid receptor 1 is involved in renal fibrosis during chronic allograft dysfunction: Proof of concept

Chronic allograft dysfunction (CAD), defined as the replacement of functional renal tissue by extracellular matrix proteins, remains the first cause of graft loss. The aim of our study was to explore the potential role of the cannabinoid receptor 1 (CB1) during CAD. We retrospectively quantified CB1 expression and correlated it with renal fibrosis in 26 kidney‐transplanted patients who underwent serial routine kidney biopsies. Whereas CB1 expression was low in normal kidney grafts, it was highly expressed during CAD, especially in tubular cells. CB1 expression significantly increased early on after transplantation, from day 0 (D0) to month 3 post‐transplant (M3) (22.5% ± 15.4% vs 33.4% ± 13.8%, P < .01), and it remained stable thereafter. CB1 expression correlated with renal fibrosis at M3 (P = .04). In an in vitro model of tacrolimus‐mediated fibrogenesis by tubular cells, we found that tacrolimus treatment significantly induced mRNA and protein expression of CB1 concomitantly to col3a1 and col4a3 up regulation. Administration of rimonabant, a CB1 antagonist, blunted collagen synthesis by tubular cells (P < .05). Overall, our study strongly suggests an involvement of the cannabinoid system in the progression of fibrosis during CAD and indicates the therapeutic potential of CB1 antagonists in this pathology.

The New Era for Reno-Cardiovascular Treatment in Type 2 Diabetes

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease in the developed world. Until 2016, the only treatment that was clearly demonstrated to delay the DKD was the renin-angiotensin system blockade, either by angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. However, this strategy only partially covered the DKD progression. Thus, new strategies for reno-cardiovascular protection in type 2 diabetic patients are urgently needed. In the last few years, hypoglycaemic drugs, such as sodium-glucose co-transporter 2 inhibitors and glucagon-like peptide-1 receptor agonists, demonstrated a cardioprotective effect, mainly in terms of decreasing hospitalization for heart failure and cardiovascular death in type 2 diabetic patients. In addition, these drugs also demonstrated a clear renoprotective effect by delaying DKD progression and decreasing albuminuria. Another hypoglycaemic drug class, dipeptidyl peptidase 4 inhibitors, has been approved for its use in patients with advanced chronic kidney disease, avoiding, in part, the need for insulinization in this group of DKD patients. Studies in diabetic and non-diabetic experimental models suggest that these drugs may exert their reno-cardiovascular protective effect by glucose and non-glucose dependent mechanisms. This review focuses on newly demonstrated strategies that have shown reno-cardiovascular benefits in type 2 diabetes and that may change diabetes management algorithms.