Oxidative stress as a culprit in diabetic kidney disease

Serum metabolic profiling in diabetic kidney disease patients using ultra-high performance liquid chromatography-tandem mass spectrometry

Background

Diabetic kidney disease (DKD) remains one of the leading causes of end-stage renal failure. The currently available diagnostic and classification markers, such as the urinary albumin-to-creatinine ratio and estimated glomerular filtration rate, demonstrate inadequate precision in forecasting the onset and progression of DKD. This study aims to investigate the serum metabolic profile of patients with DKD, with the objective of identifying reliable biomarkers that can enhance the prediction of the transition from diabetes mellitus (DM) to DKD and distinguishing DKD from nondiabetic kidney disease (NDKD).

Methods

Untargeted metabolomic analysis was performed on serum samples obtained from 53 DKD patients, 54 NDKD patients, 59 individuals diagnosed with simple diabetes mellitus (SDM), and 56 healthy controls utilizing ultra-high performance liquid chromatography-tandem mass spectrometry. Differential metabolites among the groups were identified, metabolic pathways were investigated, and the diagnostic efficacy of selected metabolites was evaluated.

Results

The metabolic enrichment pathways shared between DKD and NDKD encompassed glycerophospholipid metabolism, glycerolipid metabolism, and tryptophan metabolism. In contrast, pyrimidine metabolism and arginine biosynthesis were uniquely enriched in DKD. Compared to the NDKD group, significantly elevated levels of phosphatidylglycerol (PG, 14:0) and D-Maltose were observed in DKD patients. Additionally, in comparison to the SDM group, the DKD group exhibited significant increases in lysophosphatidic acid (LPA, 16:3), LPA (18:5), LPA (22:5), phosphatidic acid (PA, 18:3), PG (26:4), L-Glutamine, Uridine, Cytidine, Formyl-N-acetyl-5-methoxykynurenamine, 2-Oxoadipate, Thymidine, L-Citrulline, and 5-Hydroxy-L-tryptophan, while PG (28:4) levels were markedly reduced. Among these, Uridine, Cytidine, Thymidine, and L-Citrulline were associated with pyrimidine metabolism, whereas L-Glutamine and L-Citrulline participated in the arginine biosynthesis pathway. Furthermore, the differential metabolites exhibited varying degrees of correlation with renal function indicators in DKD patients.

Conclusions

PG (14:0) and D-Maltose may help distinguish DKD from NDKD, while L-Glutamine, Uridine, Cytidine, Thymidine, and L-Citrulline are linked to the progression from DM to DKD. Larger studies are needed to validate these findings and assess their diagnostic and causal significance.

Mangiferin promotes porcine oocyte maturation and delays the postovulatory aging process by up-regulating NRF2 levels

Mangiferin (MGN), a flavonoid known for its anti-inflammatory and antioxidant properties, was evaluated in this study for its effects on porcine oocyte maturation in vitro, as well as its potential to modulate the mechanisms associated with aging oocytes. The inclusion of 0.1 μM MGN in the IVM culture medium significantly enhanced blastocyst development following parthenogenetic activation, while also notably upregulating the expression of key embryonic development genes, including SOX2, PCNA, POU5F1, and DNMT3A. MGN treatment improved the oocytes' antioxidant capacity and mitochondrial functionality, concurrently reducing cathepsin B activity and lowering LC3B protein expression (1.06 ± 0.09 vs. 0.55 ± 0.12). To investigate the underlying mechanisms, NRF2 expression was assessed, revealing a marked increase in NRF2 fluorescence and a significant elevation in both NRF2 mRNA and protein levels (1.00 ± 0.05 vs. 1.25 ± 0.09) following MGN treatment compared to the control group. Additionally, MGN treatment enhanced the early developmental potential of aged oocytes, elevating GSH levels and mitochondrial membrane potential and reducing ROS accumulation. Furthermore, MGN treatment upregulated antioxidant genes (SOD1, SOD2). Collectively, these findings suggest that MGN improves porcine oocyte maturation in vitro and enhances subsequent developmental potential through the activation of NRF2 signaling. Moreover, MGN may also delay postovulatory oocyte aging by boosting antioxidant defense and mitochondrial function in aged oocytes.

A review of deoxyribonucleic acid-based single-nucleotide polymorphisms in diabetic kidney disease among Asian populations: Challenges and future directions

Diabetic kidney disease (DKD) is a persistent disorder that occurs as a result of long-term diabetes mellitus with genetic and environmental risk factors. The identification of DKD associated single-nucleotide polymorphisms (SNPs) is pivotal for patient screening. This manuscript briefly outlines the pathophysiology and the role of genetic factors in DKD expansion. It further discusses the utility of bioinformatic tools and laboratory techniques requried for the identification of DKD-specific SNPs along with integrated data analysis pipelines valuable to enhance the accuracy of genetic interpretation. A comparative analysis of various SNPs has also been made across diverse Asian populations in conjunction with environmental and lifestyle factors. The clinical relevance of SNPs in predicting DKD progression and stratifying patient risk is highlighted, with focus on gene-specific pathways and associated functional outcomes. The advances in genetic screening, gene-specific therapies, and microbiome-based therapy should help expand the utility of SNPs-based identification of DKD under diverse clinical settings. A structured clinical decision-making framework is proposed to support customized treatment based on SNP profiles. However, this domain has yet to gain widespread recognition with regard to variability in the effects of SNPs across diverse demographies, challenges in clinical translation, and ethical considerations in genetic testing.

Nrf2-dependent effects of CDDO-Me on bactericidal activity in macrophage infection models

Introduction

Diabetes and chronic kidney disease (CKD) increase susceptibility to bacterial infections, particularly Staphylococcus aureus, which is associated with highmortality in CKD patients. Dysregulated macrophage activity and excessive oxidative stress exacerbate immune dysfunction and inflammation in these conditions. Nrf2 (nuclear factor erythroid 2-related factor 2) is a key regulator of antioxidant defenses and macrophage function. CDDO-Me, a synthetic triterpenoid, activates Nrf2, providing antioxidant and anti-inflammatoryeffects. However, its precise role in modulating macrophage activity, polarization, and bacterial clearance remains unclear.

Methods

The effects of CDDO-Me on macrophage function were evaluated in vitro (THP-1 and RAW 264.7 macrophages) and an in vivo Nrf2 knockout mouse model. Nrf2 activation was assessed via Western blot and luciferase reporter assays, oxidative stress was measured using CellROX reagent, and inflammatory responses were quantified by RT-qPCR. Intracellular S. aureus survival and macrophage polarization markers were analyzed to investigate the role of CDDO-Me in enhancing bactericidal activity.

Results

Our results showed that CDDO-Me activated the Nrf2 signaling pathway, reducing oxidative stress and inflammation in macrophages by downregulating pro-inflammatory cytokines (IL-1β, TNF-α). It modulated macrophage polarization, decreasing M1 and M2 marker expression, and significantly enhanced bactericidal activity against S. aureus. These effects were Nrf2-dependent, as demonstrated in knockout models.

Conclusion

The ability of CDDO-Me to regulate oxidative stress, inflammation, and bacterial clearance underscores its therapeutic potential for managing inflammatory and infectious diseases indiabetes and CKD.

Prognostic effect of neutrophil percentage-to-albumin ratio (NPAR) on all-cause and cardiovascular mortality in diabetic kidney disease (DKD): NHANES 1999-2018

BACKGROUND

This study aimed to evaluate the associations between neutrophil percentage-to-albumin ratio (NPAR) and both all-cause and cardiovascular mortality in diabetic kidney disease (DKD) patients.

METHODS

The data for this study were sourced from the National Health and Nutrition Examination Survey (NHANES) 1999-2018. Weighted logistic regression, Cox proportional hazards model, and Fine-Gray competing risk model were used to assess the association between NPAR and both all-cause and cardiovascular mortality in DKD patients.

RESULTS

A total of 2,699 participants were enrolled in this study. Cox regression analysis revealed that elevated NPAR levels were associated with a higher risk of all-cause mortality in all participants (HR: 2.17, 95%CI: 1.83-2.58). Meanwhile, a significant difference in cardiovascular mortality was observed in males (HR: 1.83, 95%CI: 1.42-2.38) but not in females. Finally, the adjusted Fine-Gray model identified NPAR as an independent predictor of cardiovascular mortality in males (SHR: 1.86 95%CI: 1.28-2.72) but not in females.

CONCLUSIONS

In a nationally representative sample of DKD participants in the US, a significant association was detected between elevated NPAR and increased all-cause and cardiovascular mortality. In addition, gender differences in the relationship between NPAR and both all-cause and cardiovascular mortality were also observed.

Deficiency of Growth Arrest and DNA Damage-Inducible 45 α -R-Loop Pathway and Kidney Injury in Diabetic Nephropathy

Background

Diabetic nephropathy is a primary cause of kidney failure. Persistent hyperglycemia causes metabolic perturbations epigenetically dysregulating gene expression in kidney cells, thereby leading to diabetic nephropathy pathogenesis. On analyzing the Gene Expression Omnibus database by using machine learning algorithms, our preliminary results demonstrated that growth arrest and DNA damage–inducible 45α (GADD45α) might serve as key regulators in diabetic nephropathy. Furthermore, emerging evidence has shown that R-loops, the three-stranded DNA–RNA structures, are crucial to gene expression during diabetic nephropathy. Therefore, this study aimed to investigate the role of GADD45α in diabetic nephropathy by modulating epigenetic alterations through interaction with R-loops.

Methods

A diabetic mouse model was established by injecting streptozotocin intraperitoneally into mice. Kidney histology and biochemical markers were analyzed in wild-type, GADD45α knockout, and renal tubule–specific GADD45α-overexpressing mice. The GADD45α lentivirus was used to induce the overexpression of GADD45α in human kidney-2 (a proximal tubular epithelial cell line) cells, while high-glucose treatment was applied to verify the mechanisms in vitro.

Results

GADD45α expression was reduced in kidneys of diabetic nephropathy, correlating with kidney dysfunction. GADD45α knockout worsened kidney injuries, while overexpression mitigated them. Mechanistically, GADD45α interacted with R-loops on the six-transmembrane epithelial antigen of the prostate 4 (STEAP4) promoter, recruiting ten eleven translocation 1 to activate STEAP4 transcription. Deficiency in the GADD45α-R-loop pathway exacerbated mitochondrial injury, disrupted lipid metabolism, and increased oxidative stress in diabetic nephropathy.

Conclusions

Deficiency of GADD45α exacerbates diabetic nephropathy by interacting with R-loops and inhibiting STEAP4 promoter demethylation. Targeting the GADD45α-R-loop pathway offers therapeutic potential against diabetic nephropathy.

Clinical metabolomics in type 2 diabetes mellitus: from pathogenesis to biomarkers

As a multidimensional metabolic disorder, the disability and death rate of type 2 diabetes mellitus (T2DM) has increased over time. T2DM covers a wide range of pathological manifestations ranging from hyperglycemia to multi-organ failure, and it has the potential to evolve into acute complications, including ketosis and chronic complications such as peripheral neuropathy, retinopathy, and nephropathy. T2DM mainly occurs in microvascular and large vessels and thus it is restricted for the clinician to diagnose and prescribe. However, the pathological mechanism and clinical diagnosis are inadequate. High-throughput metabolomics, characterized by non-invasive diagnostic techniques to identify potential biomarkers and distinct stages of T2DM, has been increasingly recognized as a vigorous tool with latent capacity for clinical translation. The pathological stratification of T2DM can significantly reduce disability and mortality rates. By tracing the metabolome and associated pathways from impaired fasting blood glucose or impaired glucose tolerance to severe organ failure, the chief contributions of large, independent population-based cohorts are summarized herein. These results facilitate understanding the pathophysiology and mechanism and supports research in accurate diagnosis, risk prediction, curative effect, distinct stages, and prognosis judgment of T2DM.

8-hydroxy-2'-deoxyguanosine, a biomarker of oxidative DNA injury, in diabetic kidney disease

BACKGROUND AND AIMS

To gain insight into the extent of oxidative stress and DNA damage in diabetic kidney disease (DKD), a serious complication of diabetes, we compared the levels of the oxidative stress-related metabolite 8-hydroxy-2'-deoxyguanosine (8-OHdG) in a case-control study accurately matching diabetic patients with and without renal complications.

METHODS AND RESULTS

We analyzed serum 8-OHdG in relation to clinical indicators of kidney function in a group of type-2 diabetes patients including 33 patients with DKD and 33 without DKD. Circulating levels of 8-OHdG were higher in patients with DKD than in those without (4.6 ± 0.7 ng/mL vs 4.0 ± 0.8 ng/mL, p = 0.002). In a logistic regression analysis adjusting for potential confounders, 8-OHdG was associated with DKD (OR: 2.90, 95%CI:1.15-7.34; p = 0.02) and in a linear regression model, a 1 ng/mL increase of this biomarker entailed a reduction of 11.5 mL/min/1.73 m2 in the renal filtration rate. Furthermore, an interaction analysis showed that glycated hemoglobin was a modifier of the relationship between 8-OHdG and study outcomes (p for effect modification = 0.02).

CONCLUSION

This study supports the role of oxidative stress in the pathogenesis of diabetic nephropathy and highlights the potential of serum 8-OHdG as a biomarker for assessing oxidative stress and DNA damage in patients with diabetes and renal complications.

Global research hotspots and trends in oxidative stress-related diabetic nephropathy: a bibliometric study

Background

Oxidative stress is widely acknowledged as a key pathogenic mechanism in diabetic nephropathy (DN). In recent years, the role of oxidative stress in DN has garnered increasing attention. However, no bibliometric analysis has yet been conducted on the relationship between oxidative stress and DN. This study aims to systematically analyze the relevant literature, identify trends in research, assess current hotspots, and predict future directions.

Methods

We retrieved literature related to oxidative stress and DN from the Web of Science Core Collection database. We analyzed data on publication volume, countries/regions, institutions, journals, keywords, and other relevant metrics using VOSviewer, the Bibliometrix R package, and CiteSpace.

Results

From 2014 to 2024, a total of 4076 publications related to oxidative stress and DN were published across 755 journals, showing a consistent upward trend each year. China and the United States are the leading contributors in this field and demonstrate close collaborative efforts. The top contributors by country, institution, journal, and author include: China (1919 publications), Jilin University and Central South University (69 publications each), BIOMEDICINE & PHARMACOTHERAPY (117 publications), and Prof. Sun Lin (33 publications). The most frequent keyword is "oxidative stress" (3683 occurrences). In the co-citation analysis, Alicic RZ's 2017 study was the most cited (144 citations). These findings highlight the critical importance of investigating the pathogenesis of DN from the oxidative stress perspective.

Conclusion

This study demonstrates a steady increase in research on oxidative stress in DN since 2014, highlighting its central role in the pathogenesis of DN. Future research should focus on the molecular mechanisms of oxidative stress in DN and explore its therapeutic potential, to provide new strategies for the prevention and treatment of DN.

Dang-Gui-Bu-Xue decoction against diabetic nephropathy via modulating the carbonyl compounds metabolic profile and AGEs/RAGE pathway

BACKGROUND

Dang-Gui-Bu-Xue decoction (DBD) is a traditional Chinese medicine prescription clinically employed for diabetic nephropathy (DN). However, the components and pharmacological mechanisms of DBD against DN remain incompletely understood.

PURPOSE

To clarify the beneficial effect of DBD on DN and to explore its nephroprotective effect's probable mechanism and the main components.

METHODS

A diabetic mice model was established by feeding a high-fat diet (HFD) and intraperitoneal injections of streptozotocin (STZ, 40 mg‧kg-1). Subsequently, the mice were maintained on a HFD and administered with DBD. The benefits of DBD against DN were comprehensively assessed by monitoring energy and water intake, blood glucose and lipids, renal functions and pathological status. The UPLC-MS/MS was measured to detect chemical constituents in DBD and absorbed components in DBD-treated plasma under physiological and pathological states. Network pharmacology was employed to forecast the probable pathways of DBD intervention in DN, with subsequent validation of these predictions through testing biochemical parameters, anti-glycation and ELISA assays, immunofluorescence, immunohistochemistry, and western blotting. Then, a chemical derivatization method paired with UPLC-MS/MS analysis was performed to detect the carbonyl compounds in renal tissue. Finally, the main components of DBD against DN were screened by anti-glycation and MTT assays.

RESULTS

DBD regulated energy and water intakes, glucose and lipid metabolism disorders, renal dysfunction, glomerular filtration rate, renal interstitial glycogen accumulation and fibrosis in HFD/STZ-induced DN mice. A total of 129 distinct chemical constituents in DBD were characterized, of which 28 were detected in the DBD-treated plasma under a pathological state. The network pharmacological results suggested AGEs/RAGE and its downstream pathway may be a potential pathway for DBD intervention in DN. Further experiments confirmed that DBD reduced renal oxidative stress by modulating the AGEs/RAGE pathway. Moreover, 21 differential carbonyl compounds were detected between normal and DN mice, and DBD significantly modulated 16. Ultimately, seven components were screened out in DBD, which may be the main components of DBD regulating carbonyl compounds metabolic profile and AGEs/RAGE pathway.

CONCLUSION

Our findings suggested for the first time that DBD could regulate the carbonyl compounds metabolic profile and AGEs/RAGE signaling pathway to ameliorate DN.

Mechanism of metabolic memory: progression in diabetic nephropathy—a descriptive review

Diabetes mellitus and its complications exploit significantly impact global human well-being and economic burden. Previous studies and clinical trials have provided insights into the concept of metabolic memory, which sustains even after hyperglycemia has been resolved, causing diabetic complications completely. The term “metabolic memory” refers to the body’s abnormal metabolism, which can have long-term effects and influence both health and disease conditions. It involves various molecular processes causing cellular shifts, tissue and organ dysfunctions, disease progression, and effects on offspring. The conceptual framework of metabolic memory is defined and strengthened, offering a comprehensive understanding of the underlying causes of diabetic nephropathy (DN) and providing a potential new approach for diagnosing and treating the disease. In this review, we elucidated the importance, characteristics, cellular and molecular importance, and therapeutic intervention to eradicate metabolic memory in DN once hyperglycemia has been eliminated. The regulation of metabolic memory is assisted based on an epigenetic mechanism. Therefore, this report traces the significant factors involved in regulating epigenetic modifications such as DNA methylation, histone modification, and chromatin remodeling. This mechanism significantly triggers epigenetic regulation, leading to glucose stress, oxidative stress induction, and apoptosis, causing DN. It occurs beyond various signaling cascades, resulting in alterations in transcription factors and receptor molecules, which enhance the metabolic memory in the post-sustenance of hyperglycemia. This condition can be modulated based on therapeutic interventions involving lifestyle modification and the inclusion of natural substances like bioactive compounds, polyphenols, and terpenoids in the diet, followed by medications acting as epigenetic modifiers.

PDK4-mediated Nrf2 inactivation contributes to oxidative stress and diabetic kidney injury

Diabetic kidney disease (DKD) is often featured with redox dyshomeostatis. Pyruvate dehydrogenase kinase 4 (PDK4) is the hub for DKD development. However, the mechanism by which PDK4 mediates DKD is poorly understood. The current work aimed to elucidate the relationship between PDK4 and DKD from the perspective of redox manipulation. Oxidative stress was observed in the human proximal tubular cell line (HK-2 cells) treated with a high concentration of glucose and palmitic acid (HGL). The mechanistic study showed that PDK4 could upregulate Kelch-like ECH-associated protein 1 (Keap1) in HGL-treated HK-2 cells through the suppression of autophagy, resulting in the depletion of nuclear factor erythroid 2-related factor 2 (Nrf2), the master regulator of redox homeostasis. At the cellular level, pharmacological inhibition or genetic knockdown of PDK4 could boost Nrf2, followed by the increase of a plethora of antioxidant enzymes and ferroptosis-suppression enzymes. Meanwhile, the inhibition or knockdown of PDK4 remodeled iron metabolism, further mitigating oxidative stress and lipid peroxidation. The same trend was observed in the DKD mice model. The current work highlighted the role of PDK4 in the development of DKD and suggested that PDK4 might be a promising target for the management of DKD.

Phenylsulfate-induced oxidative stress and mitochondrial dysfunction in podocytes are ameliorated by Astragaloside IV activation of the SIRT1/PGC1α /Nrf1 signaling pathway

Astragaloside IV (AS-IV) exhibits diverse biological activities. Despite this, the detailed molecular mechanisms by which AS-IV ameliorates diabetic nephropathy (DN) and shields podocytes from oxidative stress (OS) and mitochondrial dysfunction remain poorly understood. In this study, we used biochemical assays, histopathological analysis, Doppler ultrasound, transmission electron microscopy，flow cytometry, fluorescence staining, and Western blotting and other methods. AS-IV was administered to db/db mice for in vivo experimentation. Our findings indicated that AS-IV treatment significantly reduced diabetes-associated markers, proteinuria, and kidney damage. It also diminished ROS levels in the kidney, enhanced the expression of endogenous antioxidant enzymes, and improved mitochondrial health. Phenyl sulfate (PS), a protein-bound uremic solute of enteric origin, has been closely linked with DN and represents a promising avenue for further research. In vitro, PS exposure induced OS and mitochondrial dysfunction in podocytes, increasing ROS levels while decreasing antioxidant enzyme activity (Catalase, Heme Oxygenase-1, Superoxide Dismutase, and Glutathione Peroxidase). ROS inhibitors (N-acetyl-L-cysteine, NAC) as the positive control group can significantly reduce the levels of ROS and restore antioxidant enzymes protein levels. Additionally, PS reduced markers associated with mitochondrial biosynthesis and function (SIRT1, PGC1α, Nrf1, and TFAM). These adverse effects were partially reversed by AS-IV treatment. However, co-treatment with AS-IV and the SIRT1 inhibitor EX527 failed to restore these indicators. Overall, our study demonstrates that AS-IV effectively attenuates DN and mitigates PS-induced OS and mitochondrial dysfunction in podocytes via the SIRT1/PGC1α/Nrf1 pathway.

Association between oxidative balance score and diabetic kidney disease, low estimated glomerular filtration rate and albuminuria in type 2 diabetes mellitus patients: a cross-sectional study

Objective

The oxidative balance score (OBS) is a comprehensive concept that includes 20 oxidative stressors and can be used to assess individual pro-oxidant versus antioxidant exposure, and the aim of the present study was to investigate the association between OBS and the risk of diabetic kidney disease (DKD), low estimated glomerular filtration rate (low-eGFR) and albuminuria in patients with diabetes mellitus (DM).

Methods

This cross-sectional study included nationally representative consecutive National Health and Nutrition Examination Survey DM patients aged 18 years and older from 2003-2018. The continuous variable OBS was converted into categorical variables by quartiles, and weighted multiple logistic regression analyses and restricted triple spline models were used to explore the relationships. We also performed subgroup analyses and interaction tests to verify the stability of the results.

Results

A total of 5389 participants were included, representing 23.6 million non-institutionalized US residents. The results from both multivariate logistic regression analysis and restricted cubic spline models indicated that OBS and dietary OBS levels were negatively associated with the risk of DKD, low-eGFR, and albuminuria, without finding a significant correlation between lifestyle OBS and these clinical outcomes. Compared to the lowest OBS quartile group, the prevalence risk of DKD (OR = 0.61, 95% CI: 0.46-0.80), low-eGFR (OR = 0.46, 95% CI: 0.33-0.64) and albuminuria (OR = 0.68, 95% CI: 0.51-0.92) decreased by 39%, 54% and 32%, respectively, in the highest OBS quartile group. The results remained stable in subgroup analyses and no interaction between subgroups was found.

Conclusion

Higher levels of OBS and dietary OBS were associated with a lower risk of DKD, low-eGFR, and albuminuria. These findings provided preliminary evidence for the importance of adhering to an antioxidant-rich diet and lifestyle among individuals with diabetes.

Renal protective effects and mechanisms of Astragalus membranaceus for diabetic kidney disease in animal models: An updated systematic review and meta-analysis

BACKGROUND

Astragalus membranaceus (AM) shows potential therapeutic benefits for managing diabetic kidney disease (DKD), a leading cause of kidney failure with no cure. However, its comprehensive effects on renal outcomes and plausible mechanisms remain unclear.

PURPOSE

This systematic review and meta-analysis aimed to synthesize the effects and mechanisms of AM on renal outcomes in DKD animal models.

METHODS

Seven electronic databases were searched for animal studies until September 2023. Risk of bias was assessed based on SYRCLE's Risk of Bias tool. Standardized mean difference (SMD) or mean difference (MD) were estimated for the effects of AM on serum creatinine (SCr), blood urea nitrogen (BUN), albuminuria, histological changes, oxidative stress, inflammation, fibrosis and glucolipids. Effects were pooled using random-effects models. Heterogeneity was presented as I2. Subgroup analysis investigated treatment- and animal-related factors for renal outcomes. Publication bias was assessed using funnel plots and Egger's test. Sensitivity analysis was performed to assess the results' robustness. RevMan 5.3 and Stata MP 15 software were used for statistical analysis.

RESULTS

Forty studies involving 1543 animals were identified for analysis. AM treatment significantly decreased SCr (MD = -19.12 μmol/l, 95 % CI: -25.02 to -13.23), BUN (MD = -6.72 mmol/l, 95 % CI: -9.32 to -4.12), urinary albumin excretion rate (SMD = -2.74, 95 % CI: -3.57, -1.90), histological changes (SMD = -2.25, 95 % CI: -3.19 to -1.32). AM treatment significantly improved anti-oxidative stress expression (SMD = 1.69, 95 % CI: 0.97 to 2.41), and decreased inflammation biomarkers (SMD = -3.58, 95 % CI: -5.21 to -1.95). AM treatment also decreased fibrosis markers (i.e. TGF-β1, CTGF, collagen IV, Wnt4 and β-catenin) and increased anti-fibrosis marker BMP-7. Blood glucose, lipids and kidney size were also improved compared with the DM control group.

CONCLUSION

AM could improve renal outcomes and alleviate injury through multiple signaling pathways. This indicates AM may be an option to consider for the development of future DKD therapeutics.

Osthole ameliorates early diabetic kidney damage by suppressing oxidative stress, inflammation and inhibiting TGF-β1/Smads signaling pathway

BACKGROUND

Osthole is a natural active ingredient extracted from the traditional Chinese medicine Cnidium monnieri. It has been demonstrated to have anti-inflammatory, anti-fibrotic, and anti-hyperglycemic properties. However, its effect on diabetic kidney disease (DKD) remains uncertain. This study aims to assess the preventive and therapeutic effects of osthole on DKD and investigate its underlying mechanisms.

METHODS

A streptozotocin/high-fat and high-sucrose diet induced Type 2 diabetic rat model was established. Metformin served as the positive drug control. Diabetic rats were treated with metformin or three different doses of osthole for 8 weeks. Throughout the treatment period, the progression of DKD was assessed by monitoring increases in urinary protein, serum creatinine, urea nitrogen, and uric acid, along with scrutinizing kidney pathology. Enzyme-linked immunosorbent assay (ELISA) was employed to detect inflammatory factors and oxidative stress levels. At the same time, immunohistochemical staining was utilized to evaluate changes in alpha-smooth muscle actin, fibronectin, E-cadherin, and apoptosis. The alterations in TGF-β1/Smads signaling pathway were ascertained through western blot and immunofluorescence. Furthermore, we constructed a high glucose-stimulated HBZY-1 cells model to uncover its molecular protective mechanism.

RESULTS

Osthole significantly reduced fasting blood glucose, insulin resistance, serum creatinine, uric acid, blood urea nitrogen, urinary protein excretion, and glomerular mesangial matrix deposition in diabetic rats. Additionally, significant improvements were observed in inflammation, oxidative stress, apoptosis, and fibrosis levels. The increase of ROS, apoptosis and hypertrophy in HBZY-1 cells induced by high glucose was reduced by osthole. Immunofluorescence and western blot results demonstrated that osthole down-regulated the TGF-β1/Smads signaling pathway and related protein expression.

CONCLUSION

Our findings indicate that osthole exhibits potential preventive and therapeutic effects on DKD. It deserves further investigation as a promising drug for preventing and treating DKD.

The therapeutic effects of marine sulfated polysaccharides on diabetic nephropathy

Marine sulfated polysaccharide (MSP) is a natural high molecular polysaccharide containing sulfate groups, which widely exists in various marine organisms. The sources determine structural variabilities of MSPs which have high security and wide biological activities, such as anticoagulation, antitumor, antivirus, immune regulation, regulation of glucose and lipid metabolism, antioxidant, etc. Due to the structural similarities between MSP and endogenous heparan sulfate, a majority of studies have shown that MSP can be used to treat diabetic nephropathy (DN) in vivo and in vitro. In this paper, we reviewed the anti-DN activities, the dominant mechanisms and structure-activity relationship of MSPs in order to provide the overall scene of MSPs as a modality of treating DN.

MicroRNA-204-5p Ameliorates Renal Injury via Regulating Keap1/Nrf2 Pathway in Diabetic Kidney Disease

Background

Diabetic kidney disease (DKD) is characterized by renal fibrosis, and the pathogenesis of renal fibrosis is still not definitely confirmed. MiR-204-5p plays an important role in the regulation of fibrosis, autophagy and oxidative stress. In this study, we aimed to investigate the role of miR-204-5p on renal damage in diabetic kidneys and the underlying mechanisms involved.

Methods

In vivo, AAV-Ksp-miR-204-5p mimics were injected into mice via tail vein. In vitro, high glucose-induced HK-2 cells were treated with miR-204-5p inhibitor, miR-204-5p mimics, ATG5 siRNA, tertiary butyl hydroquinone (TBHQ), ML385, or 3-Methyladenine (3-MA). FISH and qRT-PCR were used to detect miR-204-5p expression. The expressions of protein and mRNA were detected by Western blotting, immunofluorescence, immunohistochemistry and qRT-PCR. The concentration of fibronectin in HK-2 cells culture medium was detected by ELISA.

Results

The expression of miR-204-5p in diabetic kidneys was significantly inhibited than that in control group. Delivering miR-204-5p mimics increased miR-204-5p expression, improved renal function, inhibited renal fibrosis and oxidative stress, and restored autophagy in db/db mice. In vitro, the expression of miR-204-5p was inhibited by HG treatment in HK-2 cells. MiR-204-5p mimics effectively increased miR-204-5p expression and reduced fibronectin and collagen I expression, restored autophagy dysfunction, and increased Nrf2 expression, whereas these alterations were abrogated by Nrf2 inhibitor ML385, autophagy inhibitor 3-methyladenine (3-MA, 5 mM) treatment or ATG5 siRNA transfection in HG-induced HK-2 cells. In addition, miR-204-5p inhibitor significantly inhibited miR-204-5p expression and aggravated HG-induced fibronectin and collagen I expression, autophagy dysfunction, and decreased Nrf2 expression, while these alterations were abolished by Nrf2 activator TBHQ. Furthermore, the binding of miR-204-5p with Keap1 was confirmed by luciferase reporter assay and miR-204-5p negatively regulated Keap1 expression, resulting in the activation of Nrf2 pathway.

Conclusion

MicroRNA-204-5p protects against the progression of diabetic renal fibrosis by restoring autophagy via regulating Keap1/Nrf2 pathway.

Association of systemic immune-inflammation index with diabetic kidney disease in patients with type 2 diabetes: a cross-sectional study in Chinese population

Objective

Systemic immune-inflammation index (SII), a novel inflammatory marker, has been reported to be associated with diabetic kidney disease (DKD) in the U.S., however, such a close relationship with DKD in other countries, including China, has not been never determined. We aimed to explore the association between SII and DKD in Chinese population.

Methods

A total of 1922 hospitalized patients with type 2 diabetes mellitus (T2DM) included in this cross-sectional study were divided into three groups based on estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio (ACR): non-DKD group, DKD stages 1-2 Alb group, and DKD-non-Alb+DKD stage 3 Alb group. The possible association of SII with DKD was investigated by correlation and multivariate logistic regression analysis, and receiver-operating characteristic (ROC) curves analysis.

Results

Moving from the non-DKD group to the DKD-non-Alb+DKD stage 3 Alb group, SII level was gradually increased (P for trend <0.01). Partial correlation analysis revealed that SII was positively associated with urinary ACR and prevalence of DKD, and negatively with eGFR (all P<0.01). Multivariate logistic regression analysis showed that SII remained independently significantly associated with the presence of DKD after adjustment for all confounding factors [(odds ratio (OR), 2.735; 95% confidence interval (CI), 1.840-4.063; P < 0.01)]. Moreover, compared with subjects in the lowest quartile of SII (Q1), the fully adjusted OR for presence of DKD was 1.060 (95% CI 0.773-1.455) in Q2, 1.167 (95% CI 0.995-1.368) in Q3, 1.266 (95% CI 1.129-1.420) in the highest quartile (Q4) (P for trend <0.01). Similar results were observed in presence of DKD stages 1-2 Alb or presence of DKD-non- Alb+DKD stage 3 Alb among SII quartiles. Last, the analysis of ROC curves revealed that the best cutoff values for SII to predict DKD, Alb DKD stages 1- 2, and DKD-non-Alb+ DKD stage 3 Alb were 609.85 (sensitivity: 48.3%; specificity: 72.8%), 601.71 (sensitivity: 43.9%; specificity: 72.3%), and 589.27 (sensitivity: 61.1%; specificity: 71.1%), respectively.

Conclusion

Higher SII is independently associated with an increased risk of the presence and severity of DKD, and SII might be a promising biomarker for DKD and its distinct phenotypes in Chinese population.

Modified Hu-lu-ba-wan protects diabetic glomerular podocytes via promoting PKM2-mediated mitochondrial dynamic homeostasis

BACKGROUND

Mitochondrial dysfunction is implicated in the progression of diabetic kidney disease (DKD). Damaged mitochondria produce excessive reactive oxygen species (ROS) that can cause apoptosis. Mitochondrial dynamics control the quality and function of mitochondria. Targeting mitochondrial dynamics may reduce ROS-induced apoptosis and improve renal injury in DKD. Modified Hu-lu-ba-wan (MHLBW) shows distinct clinical effects on DKD patients, which are related to its role in antioxidant stress modulation. However, the relevant mechanisms of MHLBW have not been clearly explored.

PURPOSE

This study was aimed to evaluate the therapeutic effects of MHLBW on spontaneous DKD mice and clarify the potential mechanisms.

METHODS

The main components of MHLBW were identified by HPLC. Using db/db mice as DKD models, we evaluated the therapeutic effects of MHLBW on mice after an 8-week administration. We investigated the molecular mechanism of MHLBW in regulating mitochondrial dynamic homeostasis, podocyte apoptosis, and glomerular damage. After that, computational docking analysis and in vitro experiments were conducted for further mechanism verification.

RESULTS

Intragastric administration of MHLBW for 8 weeks in db/db mice significantly improved glucose metabolism, basement membrane thickening, mesangial expansion, glomerular fibrosis, and podocyte injury. MHLBW can reverse podocyte apoptosis via promoting mitochondrial dynamic homeostasis, which was related to regulating the PKM2/ PGC-1α/Opa1 pathway. Berberine (BBR), one of the components of MHLBW, exhibited preeminent affinity with PKM2 as reflected by computational docking analysis. In cultured podocytes, BBR can also prevent apoptosis by promoting PKM2-mediated mitochondrial dynamic homeostasis.

CONCLUSION

Our study demonstrates that MHLBW can treat DKD by inhibiting glomerular damage and podocyte apoptosis through positive regulation of PKM2-mediated mitochondrial dynamic homeostasis. These results may provide a potential strategy against DKD.

Novel pharmacological interventions for diabetic kidney disease

PURPOSE OF REVIEW

The purpose of this review is to summarize the latest evidence on the prevention and progression of diabetic kidney disease (DKD), as well as novel pharmacological interventions from preclinical and early clinical studies with promising findings in the reduction of this condition's burden.

RECENT FINDINGS

We will cover the latest evidence on the reduction of proteinuria and kidney function decline in DKD achieved through established renin-angiotensin-aldosterone system (RAAS) system blockade and the more recent addition of SGLT2i, nonsteroidal mineralocorticoid receptor antagonists (MRAs) and GLP1-RA, that combined will most likely integrate the mainstay for current DKD treatment. We also highlight evidence from new mechanisms of action in DKD, including other haemodynamic anti-inflammatory and antifibrotic interventions, oxidative stress modulators and cell identity and epigenetic targets.

SUMMARY

Renal specific outcome trials have become more popular and are increasing the available armamentarium to diminish the progression of renal decline in patients at greater risk of end-stage kidney disease (ESKD) such as diabetic individuals. A combined pharmaceutical approach based on available rigorous studies should include RAAS blockade, SGLT2 inhibitors, nonsteroidal MRA and expectedly GLP1-RA on a personalized based-intervention. New specific trials designed to address renal outcomes will be needed for innovative therapies to conclude on their potential benefits in DKD.

Unveiling FOS as a Potential Diagnostic Biomarker and Emetine as a Prospective Therapeutic Agent for Diabetic Nephropathy

Background

Diabetic nephropathy (DN) is one of the primary causes of end-stage renal disease, yet effective therapeutic targets remain elusive. This study aims to identify novel diagnostic biomarkers and potential therapeutic candidates for DN.

Methods

Differentially expressed genes (DEGs) in GSE96804 and GSE142025 were identified and functional enrichment analysis was performed. Diagnostic biomarkers were selected using machine learning algorithms and evaluated by Receiver Operating Characteristic analysis. c-Fos expression was validated in an established DN mouse model. Immune infiltration levels were assessed with Single-Sample Gene Set Enrichment Analysis. Co-expression analysis revealed regulatory relationships involving FOS. cMAP predicted potential therapeutic candidates. Transcriptome sequencing and experiments in RAW264.7 cells was performed to investigate molecular mechanisms of emetine.

Results

In both datasets, we identified 44 upregulated and 74 downregulated DEGs involved in focal adhesion, ECM-receptor interaction, and the PI3K-Akt signaling pathway. FOS emerged as a robust diagnostic marker with decreased expression in DN patients and DN mouse. Co-expression analysis revealed potential regulatory mechanisms of FOS, implicating the MAPK signaling pathway, regulation of cell proliferation and apoptotic signaling pathways. Immune dysregulation was observed in DN patients. Notably, emetine was identified as a potential therapeutic candidate. Transcriptome sequencing and experimental validation demonstrated emetine suppressed M1 macrophage polarization by inhibiting the activation of NF-κB signaling pathway, as well as reducing the expression of Il-18 and Ccl5.

Conclusion

In conclusion, our study identified FOS as a promising diagnostic biomarker and emetine as a potential therapeutic candidate for DN. These findings enhance our understanding of DN pathogenesis and present novel prospects for therapeutic strategies.

Clinical Use and Treatment Mechanism of Molecular Hydrogen in the Treatment of Various Kidney Diseases including Diabetic Kidney Disease

As diabetes rates surge globally, there is a corresponding rise in the number of patients suffering from diabetic kidney disease (DKD), a common complication of diabetes. DKD is a significant contributor to chronic kidney disease, often leading to end-stage renal failure. However, the effectiveness of current medical treatments for DKD leaves much to be desired. Molecular hydrogen (H2) is an antioxidant that selectively reduces hydroxyl radicals, a reactive oxygen species with a very potent oxidative capacity. Recent studies have demonstrated that H2 not only possesses antioxidant properties but also exhibits anti-inflammatory effects, regulates cell lethality, and modulates signal transduction. Consequently, it is now being utilized in clinical applications. Many factors contribute to the onset and progression of DKD, with mitochondrial dysfunction, oxidative stress, and inflammation being strongly implicated. Recent preclinical and clinical trials reported that substances with antioxidant properties may slow the progression of DKD. Hence, we undertook a comprehensive review of the literature focusing on animal models and human clinical trials where H2 demonstrated effectiveness against a variety of renal diseases. The collective evidence from this literature review, along with our previous findings, suggests that H2 may have therapeutic benefits for patients with DKD by enhancing mitochondrial function. To substantiate these findings, future large-scale clinical studies are needed.

The roles of gut microbiota and its metabolites in diabetic nephropathy

Diabetic nephropathy (DN) is a severe microvascular complication of diabetes, which increases the risk of renal failure and causes a high global disease burden. Due to the lack of sustainable treatment, DN has become the primary cause of end-stage renal disease worldwide. Gut microbiota and its metabolites exert critical regulatory functions in maintaining host health and are associated with many pathogenesis of aging-related chronic diseases. Currently, the theory gut-kidney axis has opened a novel angle to understand the relationship between gut microbiota and multiple kidney diseases. In recent years, accumulating evidence has revealed that the gut microbiota and their metabolites play an essential role in the pathophysiologic processes of DN through the gut-kidney axis. In this review, we summarize the current investigations of gut microbiota and microbial metabolites involvement in the progression of DN, and further discuss the potential gut microbiota-targeted therapeutic approaches for DN.