Exendin-4 Improves Diabetic Kidney Disease in C57BL/6 Mice Independent of Brown Adipose Tissue Activation

Exendin-4, a glucagon-like peptide-1 receptor agonist, alleviates muscular dysfunction and wasting in a streptozotocin-induced diabetic mouse model compared to metformin

Diabetic muscular atrophy is becoming a fast-growing problem worldwide, including sarcopenia, which is associated with substantial mortality and morbidity risk. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) have been marketed and suggested to exert protective effects on not only glycemic control but also diabetic complications in diabetic patients. In this study, we investigated the therapeutic use of GLP-1RAs exendin-4, compared to antidiabetic drug metformin, for the intervention of muscular dysfunction during diabetic conditions using a streptozotocin (STZ)-induced diabetic mouse model. The results showed that both exendin-4 and metformin could effectively alleviate hyperglycemia in diabetic mice, and also counteract diabetes-induced muscle weight loss, weaker grip, and changes in muscle fiber cross-sectional area distribution. Unexpectedly, exendin-4, but not metformin, enhanced the increased kidney weight and histological change in diabetic mice. Taken together, these findings suggest that both exendin-4 and metformin could effectively improve the diabetic hyperglycemia and muscular dysfunction; but exendin-4 may aggravate the nephropathy in STZ-induced diabetic mice.

Mitochondrial metabolic reprogramming in diabetic kidney disease

Diabetic kidney disease, known as a glomerular disease, arises from a metabolic disorder impairing renal cell function. Mitochondria, crucial organelles, play a key role in substance metabolism via oxidative phosphorylation to generate ATP. Cells undergo metabolic reprogramming as a compensatory mechanism to fulfill energy needs for survival and growth, attracting scholarly attention in recent years. Studies indicate that mitochondrial metabolic reprogramming significantly influences the pathophysiological progression of DKD. Alterations in kidney metabolism lead to abnormal expression of signaling molecules and activation of pathways, inducing oxidative stress-related cellular damage, inflammatory responses, apoptosis, and autophagy irregularities, culminating in renal fibrosis and insufficiency. This review delves into the impact of mitochondrial metabolic reprogramming on DKD pathogenesis, emphasizing the regulation of metabolic regulators and downstream signaling pathways. Therapeutic interventions targeting renal metabolic reprogramming can potentially delay DKD progression. The findings underscore the importance of focusing on metabolic reprogramming to develop safer and more effective therapeutic approaches.

Role of GLP-1 Receptor Agonist in Diabetic Cardio-renal Disorder: Recent Updates of Clinical and Pre-clinical Evidence

Cardiovascular complications and renal disease is the growing cause of mortality in patients with diabetes. The subversive complications of diabetes such as hyperglycemia, hyperlipidemia and insulin resistance lead to an increase in the risk of myocardial infarction (MI), stroke, heart failure (HF) as well as chronic kidney disease (CKD). Among the commercially available anti-hyperglycemic agents, incretin-based medications appear to be safe and effective in the treatment of type 2 diabetes mellitus (T2DM) and associated cardiovascular and renal disease. Glucagon-like peptide 1 receptor agonists (GLP-1RAs) have been shown to be fruitful in reducing HbA1c, blood glucose, lipid profile, and body weight in diabetic patients. Several preclinical and clinical studies revealed the safety, efficacy, and preventive advantages of GLP-1RAs against diabetes- induced cardiovascular and kidney disease. Data from cardio-renal outcome trials had highlighted that GLP-1RAs protected people with established CKD from significant cardiovascular disease, lowered the likelihood of hospitalization for heart failure (HHF), and lowered all-cause mortality. They also had a positive effect on people with end-stage renal disease (ESRD) and CKD. Beside clinical outcomes, GLP-1RAs reduced oxidative stress, inflammation, fibrosis, and improved lipid profile pre-clinically in diabetic models of cardiomyopathy and nephropathy that demonstrated the cardio-protective and reno-protective effect of GLP-1RAs. In this review, we have focused on the recent clinical and preclinical outcomes of GLP-1RAs as cardio-protective and reno-protective agents as GLP-1RAs medications have been demonstrated to be more effective in treating T2DM and diabetes-induced cardiovascular and renal disease than currently available treatments in clinics, without inducing hypoglycemia or weight gain.

PM2.5 exposure aggravates kidney damage by facilitating the lipid metabolism disorder in diabetic mice

Background

Ambient fine particulate matter ≤ 2.5 µm (PM2.5) air pollution exposure has been identified as a global health threat, the epidemiological evidence suggests that PM2.5 increased the risk of chronic kidney disease (CKD) among the diabetes mellitus (DM) patients. Despite the growing body of research on PM2.5 exposure, there has been limited investigation into its impact on the kidneys and the underlying mechanisms. Past studies have demonstrated that PM2.5 exposure can lead to lipid metabolism disorder, which has been linked to the development and progression of diabetic kidney disease (DKD).

Methods

In this study, db/db mice were exposed to different dosage PM2.5 for 8 weeks. The effect of PM2.5 exposure was analysis by assessment of renal function, pathological staining, immunohistochemical (IHC), quantitative real-time PCR (qPCR) and liquid chromatography with tandem mass spectrometry (LC-MS/MS) based metabolomic analyses.

Results

The increasing of Oil Red staining area and adipose differentiation related protein (ADRP) expression detected by IHC staining indicated more ectopic lipid accumulation in kidney after PM2.5 exposure, and the increasing of SREBP-1 and the declining of ATGL detected by IHC staining and qPCR indicated the disorder of lipid synthesisandlipolysis in DKD mice kidney after PM2.5 exposure. The expressions of high mobility group nucleosome binding protein 1 (HMGN1) and kidney injury molecule 1 (KIM-1) that are associated with kidney damage increased in kidney after PM2.5 exposure. Correlation analysis indicated that there was a relationship between HMGN1-KIM-1 and lipid metabolic markers. In addition, kidneys of mice were analyzed using LC-MS/MS based metabolomic analyses. PM2.5 exposure altered metabolic profiles in the mice kidney, including 50 metabolites. In conclusion the results of this study show that PM2.5 exposure lead to abnormal renal function and further promotes renal injury by disturbance of renal lipid metabolism and alter metabolic profiles.

Treatment of obesity-related diabetes: significance of thermogenic adipose tissue and targetable receptors

Diabetes mellitus is mainly classified into four types according to its pathogenesis, of which type 2 diabetes mellitus (T2DM) has the highest incidence rate and is most relevant to obesity. It is characterized by high blood glucose, which is primarily due to insulin resistance in tissues that are responsible for glucose homeostasis (such as the liver, skeletal muscle, and white adipose tissue (WAT)) combined with insufficiency of insulin secretion from pancreatic β-cells. Treatment of diabetes, especially treatment of diabetic complications (such as diabetic nephropathy), remains problematic. Obesity is one of the main causes of insulin resistance, which, however, could potentially be treated by activating thermogenic adipose tissues, like brown and beige adipose tissues, because they convert energy into heat through non-shivering thermogenesis and contribute to metabolic homeostasis. In this review, we summarize the function of certain anti-diabetic medications with known thermogenic mechanisms and focus on various receptor signaling pathways, such as previously well-known and recently discovered ones that are involved in adipose tissue-mediated thermogenesis and could be potentially targeted to combat obesity and its associated diabetes, for a better understanding of the molecular mechanisms of non-shivering thermogenesis and the development of novel therapeutic interventions for obesity-related diabetes and potentially diabetic complications.

Glucagon-Like Peptide 1 Receptor Agonist Improves Renal Tubular Damage in Mice with Diabetic Kidney Disease

PURPOSE

This study aims to investigate the renal protective effect of glucagon-like peptide 1 receptor agonist (GLP-1RA) on improving renal tubular damage in diabetic kidney disease (DKD) and to explore the potential mechanism of GLP-1RA on renal tubular protection.

METHODS

Long-acting GLP-1RA was used to treat DKD mice for 12 weeks. The label-free quantitative proteomic analysis of renal proteins was conducted to explore the differentially expressed proteins (DEPs) in the renal tissues of the control, DKD and GLP-1RA groups. The DEPs and markers of renal tubular injury were verified by qPCR in vivo and in vitro. The expression of glucagon-likepeptide-1 receptor (GLP-1R) in renal tubules was determined by immunofluorescence staining.

RESULTS

GLP-1RA treatment significantly improved the tubular damages in kidney tissues of DKD mice and mTEC cells stimulated by high glucose (HG). Proteomics analysis revealed that 30 proteins in kidney tissue were differentially expressed among three groups. Seminal vesicle secretory protein 6 (SVS6) was the most differentially expressed protein in kidney tissues among three groups of mice. The expression changes of Svs6 mRNA in vitro and in vivo detected by qPCR were consistent with the results of proteomic analysis. Furthermore, reduction of Svs6 expression by SVS6 siRNA could attenuate HG-stimulated tubular injury in mTEC cells. Immunofluorescence staining also found that GLP-1R was widely expressed in renal tubules in vitro and in vivo.

CONCLUSION

GLP-1RA significantly improved renal tubular damage in DKD mice. SVS6 may be a potential therapeutic target for GLP-1RA in the treatment of DKD.

Inflammation and Oxidative Stress in Diabetic Kidney Disease: The Targets for SGLT2 Inhibitors and GLP-1 Receptor Agonists

The incidence of type 2 diabetes (T2D) has been increasing worldwide, and diabetic kidney disease (DKD) remains one of the leading long-term complications of T2D. Several lines of evidence indicate that glucose-lowering agents prevent the onset and progression of DKD in its early stages but are of limited efficacy in later stages of DKD. However, sodium-glucose cotransporter-2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor (GLP-1R) agonists were shown to exert nephroprotective effects in patients with established DKD, i.e., those who had a reduced glomerular filtration rate. These effects cannot be solely attributed to the improved metabolic control of diabetes. In our review, we attempted to discuss the interactions of both groups of agents with inflammation and oxidative stress—the key pathways contributing to organ damage in the course of diabetes. SGLT2i and GLP-1R agonists attenuate inflammation and oxidative stress in experimental in vitro and in vivo models of DKD in several ways. In addition, we have described experiments showing the same protective mechanisms as found in DKD in non-diabetic kidney injury models as well as in some tissues and organs other than the kidney. The interaction between both drug groups, inflammation and oxidative stress appears to have a universal mechanism of organ protection in diabetes and other diseases.

Effect of Fluorofenidone Against Paraquat-Induced Pulmonary Fibrosis Based on Metabolomics and Network Pharmacology

BACKGROUND Fluorofenidone (AKF-PD) is an anti-fibrotic small-molecule compound. Its mechanism of action on paraquat (PQ)-induced pulmonary fibrosis is still unclear. MATERIAL AND METHODS Forty-eight SD rats were divided into 4 groups: control group, PQ group, PQ+AKF-PD group, and AKF-PD group. The pathological changes of lung tissues were observed by Masson and HE staining. The UPLC-QTOF-MS analysis was performed to detect the differences in metabolites among groups, then the possible mechanisms of the anti-pulmonary fibrosis effects of fluorofenidone were further revealed by network pharmacology analysis. Biological methods were used to verify the results of the network pharmacology analysis. RESULTS The results showed that fluorofenidone treatment significantly alleviated paraquat-induced pulmonary fibrosis. Metabolomics analysis showed that 18 metabolites were disordered in the serum of paraquat-poisoned rats, of which 13 were restored following fluorofenidone treatment. Network pharmacology analysis showed that the drug screened a total of 12 targets and mainly involved multiple signaling pathways and metabolic pathways to jointly exert anti-pulmonary fibrosis effects. Autophagy is the main pathway of fluorofenidone in treatment pulmonary fibrosis. The western blot results showed that fluorofenidone upregulated the expression of LC3-II/I and E-cadherin, and downregulated the expression of p62, alpha-SMA, and TGF-ß1, which validated that fluorofenidone could inhibit the development of paraquat-induced pulmonary fibrosis by increasing autophagy. CONCLUSIONS In conclusion, metabolomics combined with network pharmacology research strategy revealed that fluorofenidone has a multi-target and multi-path mechanism of action in the treatment of pulmonary fibrosis.