Accelerated Kidney Aging in Diabetes Mellitus

The interaction between klotho protein and epigenetic alteration in diabetes and treatment options

Introduction

Klotho is a membrane protein predominantly expressed in the kidneys, and its discovery was serendipitously made through gene-targeting experiments conducted on mice. Klotho has a favorable role in the regulation of multiple cellular processes, such as aging, oxidative stress, inflammation, and apoptosis. This regulation occurs through the targeting of diverse signaling molecules, cell membrane receptors, and ion channels, achieved by physical contacts or enzymatic activities of Klotho. This review examines the role of Klotho in the epigenetic regulation of molecules associated with diabetes.

Methods

Authors conducted a thorough literature search using the PubMed®, Web of Science™, and Scopus®. Relevant articles up to September 2023, published in the English language were considered. We reviewed research databases searching for studies that included keywords klotho, epigenetic, and diabetes.

Results

14 related papers about epigenetic modification of proteins involved in diabetes pathogenesis were selected to be included in this narrative review. In the studies, the kidney was the most investigated organ regarding this correlation. Also, phosphorylation and methylation were the common epigenetic modifications of proteins by Klotho.

Conclusion

Klotho has a significant role in the maturation of adipocytes and the regulation of systemic glucose metabolism, exhibiting a strong association with the pathogenesis of diabetes. Both epigenetic alterations and the modulation of protein phosphorylation by Klotho play significant roles in the regulation of Klotho expression and the modulation of other molecules implicated in the etiology of diabetes.

Network analysis to explore the anti-senescence mechanism of Jinchan Yishen Tongluo Formula (JCYSTLF) in diabetic kidneys

Background

The Jinchan Yishen Tongluo Formula (JCYSTLF) has the effect of delaying senescence in diabetic kidneys. However, the mechanism is not clear.

Purpose

Combination methods to investigate the anti-senescence mechanism of JCYSTLF in diabetic kidneys.

Methods

The main compounds of JCYSTLF were characterized by LC-MS/MS, and the anti-senescence targets of JCYSTLF were screened via network analysis. Then, we performed in vivo and in vitro experiments to validate the results.

Results

The target profiles of compounds were obtained by LC-MS/MS to characterize the primary function of JCYSTLF. Senescence was identified as a key biological functional module of JCYSTLF in the treatment of DN via constructing compounds-target-biological network analysis. Further analysis of senescence-related targets recognized the HIF-1α/autophagy pathway as the core anti-senescence mechanism of JCYSTLF in diabetic kidneys. Animal experiments showed, in comparison with valsartan, JCYSTLF showed an improvement in urinary albumin and renal pathological damage. JCYSTLF enhanced the ability of diabetic kidneys to clear senescence-related proteins via regulating autophagy confirmed by autophagy inhibitor CQ. However, HIF-1α inhibitor 2-ME weakened the role of JCYSLTF in regulating autophagy in diabetic kidneys. Meanwhile, over-expressed HIF-1α in HK-2 cells decreased the levels of SA-β-gal, p21 and p53 induced by AGEs. Upregulated HIF-1α could reverse the blocking of autophagy induced by AGEs in HK-2 cells evaluated by ptfLC3.

Conclusion

We provided in vitro and in vivo evidence for the anti-senescence role of JCYSTLF in regulating the HIF-1α/autophagy pathway.

Association of Postoperative Delirium With Incident Dementia and Graft Outcomes Among Kidney Transplant Recipients

BACKGROUND

Kidney transplant (KT) recipients have numerous risk factors for delirium, including those shared with the general surgical population (eg, age and major surgery) and transplant-specific factors (eg, neurotoxic immunosuppression medications). Evidence has linked delirium to long-term dementia risk in older adults undergoing major surgery. We sought to characterize dementia risk associated with post-KT delirium.

METHODS

Using the United States Renal Data System datasets, we identified 35 800 adult first-time KT recipients ≥55 y. We evaluated risk factors for delirium using logistic regression. We evaluated the association between delirium and incident dementia (overall and by subtype: Alzheimer's, vascular, and other/mixed-type), graft loss, and death using Fine and Gray's subhazards models and Cox regression.

RESULTS

During the KT hospitalization, 0.9% of recipients were diagnosed with delirium. Delirium risk factors included age (OR = 1.40, 95% CI, 1.28-1.52) and diabetes (OR = 1.38, 95% CI, 1.10-1.73). Delirium was associated with higher risk of death-censored graft loss (aHR = 1.52, 95% CI, 1.12-2.05) and all-cause mortality (aHR = 1.53, 95% CI, 1.25-1.89) at 5 y post-KT. Delirium was also associated with higher risk of dementia (adjusted subhazard ratio [aSHR] = 4.59, 95% CI, 3.48-6.06), particularly vascular dementia (aSHR = 2.51, 95% CI, 1.01-6.25) and other/mixed-type dementia (aSHR = 5.58, 95% CI, 4.24-7.62) subtypes. The risk of all-type dementia associated with delirium was higher for younger recipients aged between 55 and 64 y ( Pinteraction  = 0.01).

CONCLUSIONS

Delirium is a strong risk factor for subsequent diagnosis of dementia among KT recipients, particularly those aged between 55 and 64 y at the time of transplant. Patients experiencing posttransplant delirium might benefit from early interventions to enhance cognitive health and surveillance for cognitive impairment to enable early referral for dementia care.

D-ribose metabolic disorder and diabetes mellitus

D-ribose, an ubiquitous pentose compound found in all living cells, serves as a vital constituent of numerous essential biomolecules, including RNA, nucleotides, and riboflavin. It plays a crucial role in various fundamental life processes. Within the cellular milieu, exogenously supplied D-ribose can undergo phosphorylation to yield ribose-5-phosphate (R-5-P). This R-5-P compound serves a dual purpose: it not only contributes to adenosine triphosphate (ATP) production through the nonoxidative phase of the pentose phosphate pathway (PPP) but also participates in nucleotide synthesis. Consequently, D-ribose is employed both as a therapeutic agent for enhancing cardiac function in heart failure patients and as a remedy for post-exercise fatigue. Nevertheless, recent clinical studies have suggested a potential link between D-ribose metabolic disturbances and type 2 diabetes mellitus (T2DM) along with its associated complications. Additionally, certain in vitro experiments have indicated that exogenous D-ribose exposure could trigger apoptosis in specific cell lines. This article comprehensively reviews the current advancements in D-ribose's digestion, absorption, transmembrane transport, intracellular metabolic pathways, impact on cellular behaviour, and elevated levels in diabetes mellitus. It also identifies areas requiring further investigation.

Identification of Senescence-Associated Biomarkers in Diabetic Glomerulopathy Using Integrated Bioinformatics Analysis

Background

Cellular senescence is thought to play a significant role in the onset and development of diabetic nephropathy. The goal of this study was to explore potential biomarkers associated with diabetic glomerulopathy from the perspective of senescence.

Methods

Datasets about human glomerular biopsy samples related to diabetic nephropathy were systematically obtained from the Gene Expression Omnibus database. Hub senescence-associated genes were investigated by differential gene analysis and Least Absolute Shrinkage and Selection Operator analysis. Cluster analysis was employed to identify senescence molecular subtypes. A single-cell dataset was used to validate the above findings and further evaluate the senescence environment. The relationship between these genes and the glomerular filtration rate was explored based on the Nephroseq database. These gene expressions have also been explored in various kidney diseases.

Results

Twelve representative senescence-associated genes (VEGFA, IQGAP2, JUN, PLAT, ETS2, ANG, MMP14, VEGFC, SERPINE2, CXCR2, PTGES, and EGF) were finally identified. Biological changes in immune inflammatory response, cell cycle regulation, metabolic regulation, and immune microenvironment have been observed across different molecular subtypes. The above results were also validated based on single-cell analysis. Additionally, we also identified several significantly altered cell communication pathways, including COLLAGEN, PTN, LAMININ, SPP1, and VEGF. Finally, almost all these genes could well predict the occurrence of diabetic glomerulopathy based on receiver operating characteristic analysis and are associated with the glomerular filtration rate. These genes are differently expressed in various kidney diseases.

Conclusion

The present study identified potential senescence-associated biomarkers and further explored the heterogeneity of diabetic glomerulopathy that might provide new insights into the diagnosis, assessment, management, and personalized treatment of DN.

Integrative analysis of potential diagnostic markers and therapeutic targets for glomerulus-associated diabetic nephropathy based on cellular senescence

Introduction

Diabetic nephropathy (DN), distinguished by detrimental changes in the renal glomeruli, is regarded as the leading cause of death from end-stage renal disease among diabetics. Cellular senescence plays a paramount role, profoundly affecting the onset and progression of chronic kidney disease (CKD) and acute kidney injuries. This study was designed to delve deeply into the pathological mechanisms between glomerulus-associated DN and cellular senescence.

Methods

Glomerulus-associated DN datasets and cellular senescence-related genes were acquired from the Gene Expression Omnibus (GEO) and CellAge database respectively. By integrating bioinformatics and machine learning methodologies including the LASSO regression analysis and Random Forest, we screened out four signature genes. The receiver operating characteristic (ROC) curve was performed to evaluate the diagnostic performance of the selected genes. Rigorous experimental validations were subsequently conducted in the mouse model to corroborate the identification of three signature genes, namely LOX, FOXD1 and GJA1. Molecular docking with chlorogenic acids (CGA) was further established not only to validate LOX, FOXD1 and GJA1 as diagnostic markers but also reveal their potential therapeutic effects.

Results and discussion

In conclusion, our findings pinpointed three diagnostic markers of glomerulus-associated DN on the basis of cellular senescence. These markers could not only predict an increased risk of DN progression but also present promising therapeutic targets, potentially ushering in innovative treatments for DN in the elderly population.

Chronic Kidney Disease in the Older Adult Patient with Diabetes

Diabetes mellitus (DM) and chronic kidney disease (CKD) are common in middle aged and older adult individuals. DM may accelerate the aging process, and the age-related declines in the estimated glomerular filtration rate (eGFR) can pose a challenge to diagnosing diabetic kidney disease (DKD) using standard diagnostic criteria especially with the absence of severe albuminuria among older adults. In the presence of CKD and DM, older adult patients may need multidisciplinary care due to susceptibility to various health issues, e.g., cognitive decline, auditory or visual impairment, various comorbidities, complex medical regimens, and increased sensitivity to medication adverse effects. As a result, it can be challenging to apply recent therapeutic advancements for the general population to older adults. We review the evidence that the benefits from these newer therapies apply equally to older and younger patients with CKD and diabetes type 2 and propose a comprehensive management. This framework will address nonpharmacological measures and pharmacological management with renin angiotensin system inhibitors (RASi), sodium glucose co-transporter 2 inhibitors (SGLT2i), non-steroidal mineralocorticoids receptor antagonists (MRAs), and glucagon like peptide 1 receptor agonists (GLP1-RAs).

[Research Progress in Stress-Induced Senescence of Renal Tubular Cells in Diabetic Nephropathy]

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease. Renal tubulointerstitial injury is an important pathophysiological basis that contributes to the progression of DN to end-stage renal disease. Stress-induced senescence of renal tubular epithelial cells (RTECs) forms a key link that causes tubulointerstitial injury. In recent years, it has been reported that organelles, such as endoplasmic reticulum, mitochondria, and lysosomes, in RTECs are damaged to varying degrees in DN, and that their functional imbalance may lead to stress-induced senescence of RTECs, thereby causing sustained cellular and tissue-organ damage, which in turn promotes the progression of the disease. However, the core mechanism underlying changes in the senescence microenvironment caused by stress-induced senescence of RTECs in DN is still not understood. In addition, the mechanism by which organelles lose homeostasis also needs to be further investigated. Herein, we described the specific pathophysiological mechanisms of renal tubular injury, stress-induced senescence of RTECs, and their association with organelles in the context of DN in order to provide reference for the next-step research, as well as the development of new therapeutic strategies.

Melatonin attenuates cellular senescence and apoptosis in diabetic nephropathy by regulating STAT3 phosphorylation

AIMS

Melatonin is an endogenous hormone related to the regulation of biorhythm. Previous researchers have found that melatonin can ameliorate diabetic nephropathy (DN), but the mechanism remains to be elucidated. To discover the possible mechanism by which melatonin prevents DN, we investigated the potential effects of melatonin on signal transducer and activator of transcription 3 (STAT3) on the progression of cellular senescence and apoptosis.

MAIN METHODS

Cellular senescence, apoptosis and the underlying mechanism of melatonin were investigated both in vivo and in vitro. C57BL/6 mice were intraperitoneally injected with streptozotocin (STZ) to establish DN. For an in vitro model of DN, human renal cortex proximal epithelial tubule (HK-2) cells were exposed to high glucose conditions.

KEY FINDINGS

Melatonin inhibited the phosphorylation of STAT3, decreased the expression of senescence proteins p53, p21 and p16INK4A. Melatonin also downregulated the expression of apoptotic proteins, including cleaved PARP1, cleaved caspase-9 and -3. Melatonin treatment decreased the positive area of senescence-associated galactosidase (SA-β-gal) staining and the number of TUNEL-positive cells in kidneys of DN mice. In vitro, melatonin inhibited STAT3 phosphorylation and lowered cellular senescence and apoptosis markers, in a manner similar to the STAT3 inhibitor S3I-201. In addition, the inhibition effect of melatonin on cellular senescence and apoptosis in HK-2 cells was reversed by the usage of recombinant IL-6 (rIL-6), which can induce STAT3 phosphorylation.

SIGNIFICANCE

We, for the first time, demonstrate that melatonin inhibits STAT3 phosphorylation, which is involved in alleviating the cellular senescence and apoptosis in DN.

Supplementation with l-arginine and nitrates vs age and individual physiological reactivity

Ageing is a natural ontogenetic phenomenon that entails a decrease in the adaptive capacity of the organism, as a result of which the body becomes less adaptable to stressful conditions. Nitrate and nitrite enter the body from exogenous sources and from nitrification of ammonia nitrogen by intestinal microorganisms. This review considers the mechanisms of action of l-arginine, a known inducer of nitric oxide (NO) biosynthesis, and nitrates as supplements in the processes of ageing and aggravated stress states, in which mechanisms of individual physiological reactivity play an important role. This approach can be used as an element of individual therapy or prevention of premature ageing processes depending on the different levels of initial reactivity of the functional systems. A search was performed of the PubMed, Scopus, and Google Scholar databases (n = 181 articles) and the author's own research (n = 4) up to May 5, 2023. The review presents analyses of data on targeted treatment of NO generation by supplementation with l-arginine or nitrates, which is a promising means for prevention of hypoxic conditions frequently accompanying pathological processes in an ageing organism. The review clarifies the role of the individual state of physiological reactivity, using the example of individuals with a high predominance of cholinergic regulatory mechanisms who already have a significant reserve of adaptive capacity. In studies of the predominance of adrenergic influences, a poorly trained organism as well as an elderly organism correspond to low resistance, which is an additional factor of damage at increased energy expenditure. Conclusion: It is suggested that the role of NO synthesis from supplementation of dietary nitrates and nitrites increases with age rather than from oxygen-dependent biosynthetic reactions from l-arginine supplementation.

SIRT6's function in controlling the metabolism of lipids and glucose in diabetic nephropathy

Diabetic nephropathy (DN) is a complication of diabetes mellitus (DM) and the main cause of excess mortality in patients with type 2 DM. The pathogenesis and progression of DN are closely associated with disorders of glucose and lipid metabolism. As a member of the sirtuin family, SIRT6 has deacetylation, defatty-acylation, and adenosine diphosphate-ribosylation enzyme activities as well as anti-aging and anticancer activities. SIRT6 plays an important role in glucose and lipid metabolism and signaling, especially in DN. SIRT6 improves glucose and lipid metabolism by controlling glycolysis and gluconeogenesis, affecting insulin secretion and transmission and regulating lipid decomposition, transport, and synthesis. Targeting SIRT6 may provide a new therapeutic strategy for DN by improving glucose and lipid metabolism. This review elaborates on the important role of SIRT6 in glucose and lipid metabolism, discusses the potential of SIRT6 as a therapeutic target to improve glucose and lipid metabolism and alleviate DN occurrence and progression of DN, and describes the prospects for future research.

Pharmacological potentials of lycopene against aging and aging-related disorders: A review

Aging and aging-related chronic disorders are one of the principal causes of death worldwide. The prevalence of these disorders is increasing gradually and globally. Considering this unwavering acceleration of the global burden, seeking alternatives to traditional medication to prevent the risk of aging disorders is needed. Among them, lycopene, a carotenoid, is abundant in many fruits and vegetables, including tomatoes, grapefruits, and watermelons, and it has a unique chemical structure to be a potent antioxidant compound. This nutraceutical also possesses several anti-aging actions, including combating aging biomarkers and ameliorating several chronic disorders. However, no systematic evaluation has yet been carried out that can comprehensively elucidate the effectiveness of lycopene in halting the course of aging and the emergence of chronic diseases linked to aging. This review, therefore, incorporates previous pre-clinical, clinical, and epidemiological studies on lycopene to understand its potency in treating aging disorders and its role as a mimic of caloric restriction. Lycopene-rich foods are found to prevent or attenuate aging disorders in various research. Based on the evidence, this review suggests the clinical application of lycopene to improve human health and alleviate the prevalence of aging and aging disorders.

JAK/STAT signaling in diabetic kidney disease

Diabetic kidney disease (DKD) is the most important microvascular complication of diabetes and the leading cause of end-stage renal disease (ESRD) worldwide. The Janus kinase/signal transducer and activator of the transcription (JAK/STAT) signaling pathway, which is out of balance in the context of DKD, acts through a range of metabolism-related cytokines and hormones. JAK/STAT is the primary signaling node in the progression of DKD. The latest research on JAK/STAT signaling helps determine the role of this pathway in the factors associated with DKD progression. These factors include the renin-angiotensin system (RAS), fibrosis, immunity, inflammation, aging, autophagy, and EMT. This review epitomizes the progress in understanding the complicated explanation of the etiologies of DKD and the role of the JAK/STAT pathway in the progression of DKD and discusses whether it can be a potential target for treating DKD. It further summarizes the JAK/STAT inhibitors, natural products, and other drugs that are promising for treating DKD and discusses how these inhibitors can alleviate DKD to explore possible potential drugs that will contribute to formulating effective treatment strategies for DKD in the near future.

Economic evaluation of bailing capsules for patients with diabetic nephropathy in China

Background: Diabetic nephropathy is a major microvascular complication and the main cause of end-stage renal disease in diabetic patients. The therapeutic effects of Bailing capsules for diabetic nephropathy have already been demonstrated; however, the cost-effectiveness of Bailing capsules remains controversial. This study aimed to evaluate the cost-effectiveness of Bailing capsules combined with Western medicine compared with Western medicine alone in diabetic nephropathy from a Chinese healthcare system perspective. Methods: A Markov model was established to simulate the disease process of patients over a 20-year period. Clinical efficacy data were obtained from a meta-analysis, and transition probability was estimated based on microsimulation. Direct costs and utility values were collected from the Chinese Drug Bidding Database (https://www.shuju.menet.com.cn) and published literature. The incremental cost-effectiveness ratio (ICER) was measured, and one-way and probabilistic sensitivity analyses were performed to observe model stability. Results: A total of 34 randomized controlled trials involving 3,444 patients with diabetic nephropathy were selected for the meta-analysis. Compared to Western medicine alone, the addition of Bailing capsules resulted in an increase of 0.39 quality-adjusted life-years (QALYs) and additional costs of Chinese Yuan (CNY) 24,721, yielding an ICER of CNY 63,001 per QALY gained. The ICER was lower than the threshold of willingness-to-pay of CNY 80,976 (The GDP per Capita in China). The reliability and stability of the results were confirmed by the sensitivity analysis. Conclusion: We found that Bailing capsules may be a cost-effective treatment choice for patients with diabetic nephropathy in the Chinese population.

Structural and physiological changes of the kidney with age and its impact on chronic conditions and COVID-19

The kidney is an essential organ that removes waste products, balances the body's fluids, releases hormones that regulate blood pressure, produces an active form of vitamin D, promotes healthy bones, and controls the production of red blood cells. Structural and functional abnormalities occur in kidney with age. Alterations in kidney structure are based on physiological functions and environmental pressures. Variations in its structure across vertebrates are primarily due to the nature of alterations in number, complexity, arrangement, and location of the kidney tubules. Globally, individuals aged 65 and older are part of the fastest expanding population demographic, and as a result, a greater number of older patients are receiving a diagnosis of impaired renal function. The purpose of our mini-review is to summarize recent findings of the structural and functional differences between the normal and aging kidney, examine the evolutionary biology of the kidney across species, and demonstrate the role of aging in conditions such as diabetes, chronic kidney disease, and hypertension, along with their impact on SARS-CoV-2. Additional aims include discussing the potential therapeutic strategies to treat aged individuals with kidney health issues and how the impact of a healthy lifestyle, diet, and exercise can improve health conditions with aged kidneys.

The combination of linagliptin and metformin rescues bone loss in type 2 diabetic osteoporosis

To develop an approach to reduce the type 2 diabetic osteoporosis, this study investigated the protective effects of the combination of linagliptin and metformin against osteoporosis. Micro-CT and dynamic biomechanical measurements were used to determine the bone microstructure in the type 2 diabetes mellitus (T2DM) rats. MC3T3-E1 cells were cultured in high glucose environments. In addition, we used qRT-PCR and Western blotting to assess osteogenic markers and p38 and extracellular signal-regulated kinase (ERK) protein expression. The combination of linagliptin and metformin treatment significantly restored bone micro-architecture and femoral mechanical properties in the T2DM rats. In contrast, bone markers including osteocalcin, NH2-terminal propeptide of type I procollagen, COOH-terminal telopeptide of type I collagen and tartrate-resistant acid phosphatase were significantly reduced by the combination of linagliptin and metformin treatment. We used high glucose treated MC3T3-E1 cells to mimic the condition of T2DM. Linagliptin combined with metformin treatment significantly inhibited the phosphorylation of p38 and ERK induced by high glucose treatment. In conclusion, the linagliptin combined with metformin treatment improved the rats' bone mineral density, bone structure, and osteogenic markers. Both p38 and ERK phosphorylation were reduced in high glucose MC3T3-E1 cells. Our findings highlight the potential of linagliptin combined with metformin for the treatment of T2DM-related osteoporosis.

Newer Glucose-Lowering Therapies in Older Adults with Type 2 Diabetes

Diabetes is prevalent in older adults and older adults with diabetes are more likely to have multiple comorbidities. It is, therefore, important to personalize diabetes management in this group. Newer glucose-lowering drugs, including dipeptidyl peptidase-4 inhibitors, sodium-glucose cotransporter 2 inhibitors, and glucagon-like peptide-1 receptor agonists can be safely used in older patients and are preferred choices in many cases due to their safety, efficacy, and low risk of hypoglycemia.

Resveratrol Alleviates Advanced Glycation End-Products-Related Renal Dysfunction in D-Galactose-Induced Aging Mice

The elderly have higher concentrations of advanced glycation end-products (AGEs). AGEs are considered risk factors that accelerate aging and cause diabetic nephropathy. The effects of AGEs on renal function in the elderly remain to be clarified. This study aimed to explore the role of AGEs in renal function decline in the elderly and the protective effect of resveratrol, a stilbenoid polyphenol, comparing it with aminoguanidine (an AGEs inhibitor). A D-galactose-induced aging mouse model was used to explore the role of AGEs in the process of renal aging. The mice were administered D-galactose subcutaneously for eight weeks in the presence or absence of orally administered aminoguanidine or resveratrol. The results showed that the serum levels of AGEs and renal function markers BUN, creatinine, and cystatin C in the mice significantly increased after the administration of D-galactose, and this outcome could be significantly reversed by treatment with aminoguanidine or resveratrol. The protein expression levels for apoptosis, fibrosis, and aging-related indicators in the kidneys were significantly increased, which could also be reversed by treatment with aminoguanidine or resveratrol. These findings suggest that resveratrol could alleviate AGEs-related renal dysfunction through the improvement of renal cellular senescence, apoptosis, and fibrosis in D-galactose-induced aging in mice.

Cardiometabolic index is associated with urinary albumin excretion and renal function in aged person over 60: Data from NHANES 2011-2018

PURPOSE

Cardiometabolic index (CMI) is recently considered to have certain significance in the screening of diabetes, atherosclerosis, and renal dysfunction. Therefore, this study intends to explore the relationship between CMI and the risk of albuminuria.

METHODS

This is a cross-sectional study involving 2732 elderly people (age ≥ 60). The research data are from the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2018. Calculate CMI index: Triglyceride (TG) (mmol/L)/ High density lipid-cholesterol (HDLC) (mmol/L) × WHtR.

RESULTS

The CMI level in microalbuminuria group was significantly higher than that in normal albuminuria group (P < 0.05 or P < 0.01), whether in the general population or in diabetes and hypertensive population respectively. The proportion of abnormal microalbuminuria increased gradually with the increase of CMI tertile interval (P < 0.01). Correlation analysis showed that CMI was positively correlated with urinary albumin-creatinine ratio (UACR), blood urea nitrogen (BUN), and serum creatinine (Scr), and negatively correlated with estimated glomerular filtration rate (eGFR). With the occurrence of albuminuria as the dependent variable, weighted logistic regression analysis showed that CMI was an independent risk factor for microalbuminuria. Weighted smooth curve fitting showed that CMI index was linearly related to the risk of microalbuminuria. Subgroup analysis and interaction test showed that they participated in this positive correlation.

CONCLUSIONS

Obviously, CMI is independently associated with microalbuminuria, suggesting that CMI, a simple indicator, can be used for risk assessment of microalbuminuria, especially in diabetes patients.

The Role of Ketone Bodies in Various Animal Models of Kidney Disease

The kidney is a vital organ that carries out significant metabolic functions in our body. Due to the complexity of its role, the kidney is also susceptible to many disease conditions, such as acute kidney injury (AKI) and chronic kidney disease (CKD). Despite the prevalence and our increased understanding of the pathophysiology of both AKI and CKD as well as the transition of AKI to CKD, no well-established therapeutics have been applied clinically to these conditions, rendering an urgent need for a novel potential therapeutic target to be developed. In this article, we reviewed the function of ketone bodies in some common kidney conditions, such as drug-induced nephrotoxicity, ischemia and reperfusion injury, fibrosis development, diabetic kidney disease, kidney aging, hypertension, and CKD progression. All the selected studies reviewed were performed in animal models by primarily utilizing rodents, which also provide invaluable sources for future clinical applications. Ketone bodies have shown significant renal protective properties via attenuation of oxidative stress, increased expression of anti-inflammatory proteins, gene regulation, and a reduction of apoptosis of renal cells. A physiological level of ketone bodies could be achieved by fasting, a ketogenic diet, and an exogenous ketone supplement. Finally, the limitations of the long-term ketogenic diet were also discussed.

Harnessing Genomic Analysis to Explore the Role of Telomeres in the Pathogenesis and Progression of Diabetic Kidney Disease

The prevalence of diabetes is increasing globally, and this trend is predicted to continue for future decades. Research is needed to uncover new ways to manage diabetes and its co-morbidities. A significant secondary complication of diabetes is kidney disease, which can ultimately result in the need for renal replacement therapy, via dialysis or transplantation. Diabetic kidney disease presents a substantial burden to patients, their families and global healthcare services. This review highlights studies that have harnessed genomic, epigenomic and functional prediction tools to uncover novel genes and pathways associated with DKD that are useful for the identification of therapeutic targets or novel biomarkers for risk stratification. Telomere length regulation is a specific pathway gaining attention recently because of its association with DKD. Researchers are employing both observational and genetics-based studies to identify telomere-related genes associated with kidney function decline in diabetes. Studies have also uncovered novel functions for telomere-related genes beyond the immediate regulation of telomere length, such as transcriptional regulation and inflammation. This review summarises studies that have revealed the potential to harness therapeutics that modulate telomere length, or the associated epigenetic modifications, for the treatment of DKD, to potentially slow renal function decline and reduce the global burden of this disease.

The Mechanism of Hyperglycemia-Induced Renal Cell Injury in Diabetic Nephropathy Disease: An Update

Diabetic Nephropathy (DN) is a serious complication of type I and II diabetes. It develops from the initial microproteinuria to end-stage renal failure. The main initiator for DN is chronic hyperglycemia. Hyperglycemia (HG) can stimulate the resident and non-resident renal cells to produce humoral mediators and cytokines that can lead to functional and phenotypic changes in renal cells and tissues, interference with cell growth, interacting proteins, advanced glycation end products (AGEs), etc., ultimately resulting in glomerular and tubular damage and the onset of kidney disease. Therefore, poor blood glucose control is a particularly important risk factor for the development of DN. In this paper, the types and mechanisms of DN cell damage are classified and summarized by reviewing the related literature concerning the effect of hyperglycemia on the development of DN. At the cellular level, we summarize the mechanisms and effects of renal damage by hyperglycemia. This is expected to provide therapeutic ideas and inspiration for further studies on the treatment of patients with DN.

Structural and Functional Changes in Aging Kidneys

The renal condition is one of the crucial predictors of longevity; therefore, early diagnosis of any dysfunction plays an important role. Kidneys are highly susceptible to the aging process. Unfavorable conditions may lead to a significant disturbance of the body's homeostasis. Apart from physiological changes, there are some conditions such as hypertension, diabetes or obesity which contribute to the acceleration of the aging process. A determination of macroscopic and microscopic changes is essential for assessing the progression of aging. With age, we observe a decrease in the volume of renal parenchyma and an increase in adipose tissue in the renal sinuses. Senescence may also be manifested by the roughness of the kidney surface or simple renal cysts. The main microscopic changes are a thickening of the glomerular basement membrane, nephrosclerosis, an accumulation of extracellular matrix, and mesangial widening. The principal aspect of stopping unfavorable changes is to maintain health. Studies have shown many useful ways to mitigate renal aging. This review is focused especially on medications such as renin-angiotensin-aldosterone system blockers or resveratrol, but even eating habits and lifestyle.

Advanced glycation end products induce senescence of atrial myocytes and increase susceptibility of atrial fibrillation in diabetic mice

Diabetes mellitus (DM) is a common chronic metabolic disease caused by significant accumulation of advanced glycation end products (AGEs). Atrial fibrillation (AF) is a common cardiovascular complication of DM. Here, we aim to clarify the role and mechanism of atrial myocyte senescence in the susceptibility of AF in diabetes. Rapid transesophageal atrial pacing was used to monitor the susceptibility of mice to AF. Whole-cell patch-clamp was employed to record the action potential (AP) and ion channels in single HL-1 cell and mouse atrial myocytes. More importantly, anti-RAGE antibody and RAGE-siRNA AAV9 were used to investigate the relationship among diabetes, aging, and AF. The results showed that elevated levels of p16 and retinoblastoma (Rb) protein in the atrium were associated with increased susceptibility to AF in diabetic mice. Mechanistically, AGEs increased p16/Rb protein expression and the number of SA-β-gal-positive cells, prolonged the action potential duration (APD), reduced protein levels of Cav1.2, Kv1.5, and current density of I_Ca,L , I_Kur in HL-1 cells. Anti-RAGE antibody or RAGE-siRNA AAV9 reversed these effects in vitro and in vivo, respectively. Furthermore, downregulating p16 or Rb by siRNA prevented AGEs-mediated reduction of Cav1.2 and Kv1.5 proteins expression. In conclusion, AGEs accelerated atrial electrical remodeling and cellular senescence, contributing to increased AF susceptibility by activating the p16/Rb pathway. Inhibition of RAGE or the p16/Rb pathway may be a potential therapeutic target for AF in diabetes.

Changes of macrophage and CD4+ T cell in inflammatory response in type 1 diabetic mice

Immune cells play an important role in the development of inflammation in type 1 diabetes mellitus, so we want to explore the changes of CD4+ T cells and macrophages in vivo, which can provide an experimental basis for immunotherapy based on CD4+ T cells and macrophages. The intraperitoneal injection of streptozocin was used to induce a type 1 diabetes mellitus mouse model; the blood glucose, body weight, and the expression of inflammatory factors in the kidney were measured. Immunohistochemistry was applied to determine and analyze the infiltration of CD4+ T cells and macrophages in the spleen, pancreas, and kidney. The subtypes of macrophages in the kidney and CD4+ T cells in the spleen were analyzed by flow cytometry. Our study suggests that CD4+ T cells and macrophages increase, while the inflammatory immune response system is activated in the development of T1DM. CD4+ T cells positively correlated with macrophages in the pancreas and kidney of T1DM. CD4+ T cells turn to pro-inflammatory subtypes in the spleen of T1DM, while macrophages turn to pro-inflammatory subtypes in the kidney of T1DM. Therefore, regulation of CD4+ T cells and macrophages may be a potential target for T1DM and kidney complications.

Comprehensive bibliometric analysis of sirtuins: Focus on sirt1 and kidney disease

Sirtuins, as regulators of metabolism and energy, have been found to play an important role in health and disease. Sirt1, the most widely studied member of the sirtuin family, can ameliorate oxidative stress, immune inflammation, autophagy, and mitochondrial homeostasis by deacetylating regulatory histone and nonhistone proteins. Notably, sirt1 has gradually gained attention in kidney disease research. Therefore, an evaluation of the overall distribution of publications concerning sirt1 based on bibliometric analysis methods to understand the thematic evolution and emerging research trends is necessary to discover topics with potential implications for kidney disease research. We conducted a bibliometric analysis of publications derived from the Web of Science Core Collection and found that publications concerning sirt1 have grown dramatically over the past 2 decades, especially in the past 5 years. Among these, the proportion of publications regarding kidney diseases have increased annually. China and the United States are major contributors to the study of sirt1, and Japanese researchers have made important contributions to the study of sirt1 in kidney disease. Obesity, and Alzheimer’s disease are hotspots diseases for the study of sirt1, while diabetic nephropathy is regarded as a research hotspot in the study of sirt1 in kidney disease. NAD⁺, oxidative stress, and p53 are the focus of the sirt1 research field. Autophagy and NLRP3 inflammasome are emerging research trends have gradually attracted the interest of scholars in sirt1, as well as in kidney disease. Notably, we also identified several potential research topics that may link sirt1 and kidney disease, which require further study, including immune function, metabolic reprogramming, and fecal microbiota.

Diagnostic and Therapeutic Roles of Extracellular Vesicles in Aging-Related Diseases

Aging shows a decline in overall physical function, and cellular senescence is the powerful catalyst leading to aging. Considering that aging will be accompanied with the emergence of various aging-related diseases, research on new antiaging drugs is still valuable. Extracellular vesicles (EVs), as tools for intercellular communication, are important components of the senescence-associated secretory phenotype (SASP), and they can play pathological roles in the process of cellular senescence. In addition, EVs are similar to their original cells in functions. Therefore, EVs derived from pathological tissues or body fluids may be closely related to the progression of diseases and become potential biomarkers, while those from healthy cells may have therapeutic effects. Moreover, EVs are satisfactory drug carriers. At present, numerous studies have supported the idea that engineered EVs could improve drug targeting ability and utilization efficiency. Here, we summarize the characteristics of EVs and cellular senescence and focus on the diagnostic and therapeutic potential of EVs in various aging-related diseases, including Alzheimer disease, osteoporosis, cardiovascular disease, diabetes mellitus and its complications, and skin aging.

Harnessing the Full Potential of Multi-Omic Analyses to Advance the Study and Treatment of Chronic Kidney Disease

Chronic kidney disease (CKD) was the 12th leading cause of death globally in 2017 with the prevalence of CKD estimated at ~9%. Early detection and intervention for CKD may improve patient outcomes, but standard testing approaches even in developed countries do not facilitate identification of patients at high risk of developing CKD, nor those progressing to end-stage kidney disease (ESKD). Recent advances in CKD research are moving towards a more personalised approach for CKD. Heritability for CKD ranges from 30% to 75%, yet identified genetic risk factors account for only a small proportion of the inherited contribution to CKD. More in depth analysis of genomic sequencing data in large cohorts is revealing new genetic risk factors for common diagnoses of CKD and providing novel diagnoses for rare forms of CKD. Multi-omic approaches are now being harnessed to improve our understanding of CKD and explain some of the so-called 'missing heritability'. The most common omic analyses employed for CKD are genomics, epigenomics, transcriptomics, metabolomics, proteomics and phenomics. While each of these omics have been reviewed individually, considering integrated multi-omic analysis offers considerable scope to improve our understanding and treatment of CKD. This narrative review summarises current understanding of multi-omic research alongside recent experimental and analytical approaches, discusses current challenges and future perspectives, and offers new insights for CKD.

Extracellular Vesicles Released from Stem Cells as a New Therapeutic Strategy for Primary and Secondary Glomerulonephritis

Current treatment of primary and secondary glomerulopathies is hampered by many limits and a significant proportion of these disorders still evolves towards end-stage renal disease. A possible answer to this unmet challenge could be represented by therapies with stem cells, which include a variety of progenitor cell types derived from embryonic or adult tissues. Stem cell self-renewal and multi-lineage differentiation ability explain their potential to protect and regenerate injured cells, including kidney tubular cells, podocytes and endothelial cells. In addition, a broad spectrum of anti-inflammatory and immunomodulatory actions appears to interfere with the pathogenic mechanisms of glomerulonephritis. Of note, mesenchymal stromal cells have been particularly investigated as therapy for Lupus Nephritis and Diabetic Nephropathy, whereas initial evidence suggest their beneficial effects in primary glomerulopathies such as IgA nephritis. Extracellular vesicles mediate a complex intercellular communication network, shuttling proteins, nucleic acids and other bioactive molecules from origin to target cells to modulate their functions. Stem cell-derived extracellular vesicles recapitulate beneficial cytoprotective, reparative and immunomodulatory properties of parental cells and are increasingly recognized as a cell-free alternative to stem cell-based therapies for different diseases including glomerulonephritis, also considering the low risk for potential adverse effects such as maldifferentiation and tumorigenesis. We herein summarize the renoprotective potential of therapies with stem cells and extracellular vesicles derived from progenitor cells in glomerulonephritis, with a focus on their different mechanisms of actions. Technological progress and growing knowledge are paving the way for wider clinical application of regenerative medicine to primary and secondary glomerulonephritis: this multi-level, pleiotropic therapy may open new scenarios overcoming the limits and side effects of traditional treatments, although the promising results of experimental models need to be confirmed in the clinical setting.

Novel Insights into the Roles and Mechanisms of GLP-1 Receptor Agonists against Aging-Related Diseases

Aging and aging-related diseases have emerged as increasingly severe health and social problems. Therefore, it is imperative to discover novel and effective therapeutics to delay the aging process and to manage aging-related diseases. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs), one of the classes of antihyperglycemic drugs, have been recommended to manage type 2 diabetes mellitus (T2DM). Moreover, GLP-1 RAs have been shown to protect against oxidative stress, cellular senescence and chronic inflammation, which are widely accepted as the major risk factors of aging. However, their significance in aging or aging-related diseases has not been elucidated. Herein, we explain the underlying mechanisms and protective roles of GLP-1 RAs in aging from a molecular, cellular and phenotypic perspective. We provide novel insights into the broad prospect of GLP-1 RAs in preventing and treating aging-related diseases. Additionally, we highlight the gaps for further studies in clinical applications of GLP-1 RAs in aging-related diseases. This review forms a basis for further studies on the relationship between aging-related diseases and GLP-1 RAs.

Cordyceps cicadae Ameliorates Renal Hypertensive Injury and Fibrosis Through the Regulation of SIRT1-Mediated Autophagy

Hypertensive renal injury is a complication of hypertension. Cordyceps cicadae (C. cicadae) is a traditional Chinese medicine used to treat chronic kidney diseases especially renal fibrosis. Autophagy is described as a cell self-renewal process that requires lysosomal degradation and is utilized for the maintenance of cellular energy homeostasis. The present study explores the mechanism underlying C. cicadae’s renoprotection on hypertensive nephropathy (HN). First, HN rat models were established on spontaneously hypertensive rats (SHRs). The expression of fibrosis-related protein and autophagy-associated protein was detected in vivo. NRK-52E cells exposed to AngII were chosen to observe the potential health benefits of C. cicadae on renal damage. The level of extracellular matrix accumulation was detected using capillary electrophoresis immunoquantification and immunohistochemistry. After treatment with lysosomal inhibitors (chloroquine) or an autophagy activator (rapamycin), the expression of Beclin-1, LC3II, and SQSTM1/p62 was further investigated. The study also investigated the change in sirtuin1 (SIRT1), fork head box O3a (FOXO3a), and peroxidation (superoxide dismutase (SOD) and malondialdehyde (MDA)) expression when intervened by resveratrol. The changes in SIRT1 and FOXO3a were measured in patients and the SHRs. Here, we observed that C. cicadae significantly decreased damage to renal tubular epithelial cells and TGFβ1, α-smooth muscle actin (α-SMA), collagen I (Col-1), and fibronectin expression. Meanwhile, autophagy defects were observed both in vivo and in vitro. C. cicadae intervention significantly downregulated Beclin-1 and LC3II and decreased SQSTM1/p62, showing an inhibition of autophagic vesicles and the alleviation of autophagy stress. These functions were suppressed by rapamycin, and the results were just as effective as the resveratrol treatment. HN patients and the SHRs exhibited decreased levels of SIRT1 and FOXO3a. We also observed a positive correlation between SIRT1/FOXO3a and antifibrotic effects. Similar to the resveratrol group, the expression of SIRT1/FOXO3a and oxidative stress were elevated by C. cicadae in vivo. Taken together, our findings show that C. cicadae ameliorates tubulointerstitial fibrosis and delays HN progression. Renoprotection was likely attributable to the regulation of autophagic stress mediated by the SIRT1 pathway and achieved by regulating FOXO3a and oxidative stress.

Circular RNAs in Diabetic Nephropathy: Updates and Perspectives

Circular RNAs (circRNAs) are widespread endogenous transcripts lacking 5′-caps and 3′-polyadenylation tails. Their closed-loop structure confers exonuclease resistance and extreme stability. CircRNAs play essential roles in various diseases, including diabetes. Diabetic nephropathy (DN) is the leading cause of end-stage kidney disease and is one of the most common complications of diabetes. CircRNAs are key in DN and therefore important for understanding DN pathophysiology and developing new therapeutic strategies. In the present review, we briefly introduce the characteristics and functions of circRNAs and summarize recent discoveries on how circRNAs participate in DN. Based on these advances, we suggest future perspectives for studying circRNAs in DN to improve DN treatment and management.

Relationship of Soluble Klotho and Early Stage of Diabetic Nephropathy: A Systematic Review and Meta-Analysis

BACKGROUND

Diabetic nephropathy (DN) is a chronic microvascular complication caused by long-term hyperglycemia in patients with diabetes and an important cause of end-stage renal disease. Although some studies have shown that soluble Klotho(sKlotho) levels of patients with DN are lower than those without DN, in the early stage of patients with DN with normal renal function and albuminuria, the change in sKlotho is still controversial.

AIM

This meta-analysis was conducted to statistically evaluate sKlotho levels in patients with DN.

METHODS

We searched the following electronic databases: Web of Science, Embase, PubMed, Google Scholar, and China National Knowledge Infrastructure (CNKI). The following search terms were used for the title or abstract: "diabetic kidney disease", "diabetic nephropathy", OR "DN" in combination with "Klotho". The meta-analysis results were presented as standardized mean differences (SMDs) with corresponding 95% confidence intervals (CIs).

RESULTS

Fourteen articles were included in the meta-analysis. In our meta-analysis, we found that the sKlotho level in patients with DN was significantly lower than that in patients without DN (SMD: -1.52, 95% CI [-2.24, -0.80]), and it was also significantly lower in the early stage of DN (SMD: -1.65, 95% CI [-2.60, -0.70]).

CONCLUSIONS

This systematic review was the first to evaluate the relationship between sKlotho levels and DN. The sKlotho level was significantly lower in the early stages of DN, indicating that sKlotho might be a new biomarker of DN in the future.

Melatonin alleviates renal injury by activating mitophagy in diabetic nephropathy

Diabetic nephropathy (DN) causes serious renal tubule and interstitial damage, but effective prevention and treatment measures are lacking. Abnormal mitophagy may be involved in the progression of DN, but its upstream and downstream regulatory mechanisms remain unclear. Melatonin, a pineal hormone associated with circadian rhythms, is involved in regulating mitochondrial homeostasis. Here, we demonstrated abnormal mitophagy in the kidneys of DN mice or high glucose (HG)-treated HK-2 cells, which was accompanied by increased oxidative stress and inflammation. At the same time, the melatonin treatment alleviated kidney damage. After mitochondrial isolation, we found that melatonin promoted AMPK phosphorylation and accelerated the translocation of PINK1 and Parkin to the mitochondria, thereby activating mitophagy, reducing oxidative stress, and inhibiting inflammation. Interestingly, the renal protective effect of melatonin can be partially blocked by downregulation of PINK1 and inhibition of AMPK. Our studies demonstrated for the first time that melatonin plays a protective role in DN through the AMPK-PINK1-mitophagy pathway.

TangShenWeiNing Formula Prevents Diabetic Nephropathy by Protecting Podocytes Through the SIRT1/HIF-1α Pathway

BACKGROUND

Diabetic nephropathy (DN) represents a major complication of diabetes, and podocyte injury has a critical function in DN development. TangShenWeiNing formula (TSWN) has been demonstrated to efficiently decrease proteinuria and protect podocytes in DN. This work aimed to explore the mechanism by which TSWN alleviates DN and protects podocytes.

METHODS

The major bioactive components of TSWN were detected by mass spectrometry (MS) and pharmacological databases. Eight-week-old male C57BLKS/J db/m and db/db mice were provided pure water, valsartan, low dose TSWN, middle dose TSWN and high dose TSWN by gavage for 12 weeks, respectively.

RESULTS

MS and network pharmacology analyses suggested that TSWN might prevent DN through the sirtuin (SIRT)1/hypoxia-inducible factor (HIF)-1α pathway. Diabetic mice showed elevated urinary albumin in comparison with non-diabetic mice, and TSWN decreased urinary albumin in diabetic mice. Histological injury increased in the kidney in diabetic mice, which could be improved by TSWN. Fibrosis and collagen I expression were induced in the diabetic mouse kidney in comparison with the non-diabetic mouse kidney; TSWN alleviated these effects. Apoptosis and cleaved caspase-3 were induced in the diabetic mouse kidney in comparison with the non-diabetic mouse kidney, and TSWN blunted these effects. Podocytes were damaged in the diabetic mouse kidney, which was improved by TSWN. Podocin and nephrin amounts were decreased in the diabetic mouse kidney in comparison with the non-diabetic mouse kidney, and podocalyxin was increased in urine of diabetic animals in comparison with non-diabetic counterparts. After TSWN treatment, podocin and nephrin were raised in the diabetic mouse kidney, and urinary podocalyxin was depressed in diabetic animals. Diabetic mice had lower SIRT1 and higher HIF-1α amounts in kidney specimens in comparison with non-diabetic mice, and TSWN promoted SIRT1 and inhibited HIF-1α in the diabetic mouse kidney. Moreover, co-staining of SIRT1 and podocin revealed that SIRT1 decreased in podocytes from diabetic mice in comparison with those from non-diabetic mice, and TSWN elevated SIRT1 in podocytes.

CONCLUSIONS

This study indicated that TSWN alleviates DN by improving podocyte injury through the SIRT1/HIF-1α pathway in diabetic mouse kidneys.

GPCRs Are Optimal Regulators of Complex Biological Systems and Orchestrate the Interface between Health and Disease

GPCRs arguably represent the most effective current therapeutic targets for a plethora of diseases. GPCRs also possess a pivotal role in the regulation of the physiological balance between healthy and pathological conditions; thus, their importance in systems biology cannot be underestimated. The molecular diversity of GPCR signaling systems is likely to be closely associated with disease-associated changes in organismal tissue complexity and compartmentalization, thus enabling a nuanced GPCR-based capacity to interdict multiple disease pathomechanisms at a systemic level. GPCRs have been long considered as controllers of communication between tissues and cells. This communication involves the ligand-mediated control of cell surface receptors that then direct their stimuli to impact cell physiology. Given the tremendous success of GPCRs as therapeutic targets, considerable focus has been placed on the ability of these therapeutics to modulate diseases by acting at cell surface receptors. In the past decade, however, attention has focused upon how stable multiprotein GPCR superstructures, termed receptorsomes, both at the cell surface membrane and in the intracellular domain dictate and condition long-term GPCR activities associated with the regulation of protein expression patterns, cellular stress responses and DNA integrity management. The ability of these receptorsomes (often in the absence of typical cell surface ligands) to control complex cellular activities implicates them as key controllers of the functional balance between health and disease. A greater understanding of this function of GPCRs is likely to significantly augment our ability to further employ these proteins in a multitude of diseases.

Huangkui capsule in combination with metformin ameliorates diabetic nephropathy via the Klotho/TGF-β1/p38MAPK signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Huangkui capsule (HKC), extracted from Abelmoschus manihot (L.) medic (AM), as a patent proprietary Chinese medicine on the market for approximately 20 years, has been clinically used to treat chronic glomerulonephritis. Renal fibrosis has been implicated in the onset and development of diabetic nephropathy (DN). However, the potential application of HKC for preventing DN has not been evaluated.

AIM OF THE STUDY

This study was designed to investigate the efficacy and underlying mechanisms of HKC combined with metformin (MET), the first-line medication for treating type 2 diabetes, in the treatment of renal interstitial fibrosis.

MATERIALS AND METHODS

A rat model of diabetes-associated renal fibrosis was established by intraperitoneal injection of streptozotocin (STZ, 65 mg/kg) combined with a high-fat and high-glucose diet. The rats were randomly divided into five groups: normal control, DN, HKC (1.0 g/kg/day), MET (100 mg/kg/d), and HKC plus MET (1.0 g/kg/day + 100 mg/kg/d). Following drug administration for 8 weeks, we collected blood, urine, and kidney tissue for analysis. Biochemical markers and metabolic parameters were detected using commercial kits. Histopathological staining was performed to monitor morphological changes in the rat kidney. High-glucose-induced human kidney HK-2 cells were used to evaluate the renal protective effects of HKC combined with MET (100 μg/mL+10 mmol/L). MTT assay and acridine orange/ethidium bromide were used to examine cell proliferation inhibition rates and apoptosis. Immunofluorescence assay and Western blot analysis were performed to detect renal fibrosis-related proteins including Klotho, TGF-β1, and phosphorylated (p)-p38.

RESULTS

Combination therapy (HKC plus MET) significantly improved the weight, reduced blood glucose (BG), blood urea nitrogen (BUN), total cholesterol (T-CHO), triglycerides (TG), low-density lipoprotein (LDL) and increased the level of high-density lipoprotein (HDL) of DN rats. Combination therapy also significantly reduced urine serum creatinine (SCR) and urine protein (UP) levels as well as reduced the degrees of renal tubule damage and glomerulopathy in DN rats. Combination therapy ameliorated renal fibrosis, as evidenced by reduced levels of alpha-smooth muscle actin and fibronectin and increased expression of E-cadherin in the kidneys. Moreover, HKC plus MET alleviated the degree of DN in part via the Klotho/TGF-β1/p38MAPK signaling pathway. In vitro experiments showed that combination therapy significantly inhibited cell proliferation and apoptosis and regulated fibrosis-related proteins in high-glucose (HG)-induced HK-2 cells. Further studies revealed that combination therapy suppressed cell proliferation and fibrosis by inhibiting the Klotho-dependent TGF-β1/p38MAPK pathway.

CONCLUSIONS

HKC plus MET in combination suppressed abnormal renal cell proliferation and fibrosis by inhibiting the Klotho-dependent TGF-β1/p38MAPK pathway. Collectively, HKC combined with MET effectively improved DN by inhibiting renal fibrosis-associated proteins and blocking the Klotho/TGF-β1/p38MAPK signaling pathway. These findings improve the understanding of the pathogenesis of diabetes-associated complications and support that HKC plus MET combination therapy is a promising strategy for preventing DN.

Nephroprotective Effects of Synthetic Flavonoid Hidrosmin in Experimental Diabetic Nephropathy

Diabetes mellitus (DM) is a high-impact disease commonly characterized by hyperglycemia, inflammation, and oxidative stress. Diabetic nephropathy (DN) is a common diabetic microvascular complication and the leading cause of chronic kidney disease worldwide. This study investigates the protective effects of the synthetic flavonoid hidrosmin (5-O-(beta-hydroxyethyl) diosmin) in experimental DN induced by streptozotocin injection in apolipoprotein E deficient mice. Oral administration of hidrosmin (300 mg/kg/day, n = 11) to diabetic mice for 7 weeks markedly reduced albuminuria (albumin-to-creatinine ratio: 47 ± 11% vs. control) and ameliorated renal pathological damage and expression of kidney injury markers. Kidneys of hidrosmin-treated mice exhibited lower content of macrophages and T cells, reduced expression of cytokines and chemokines, and attenuated inflammatory signaling pathways. Hidrosmin treatment improved the redox balance by reducing prooxidant enzymes and enhancing antioxidant genes, and also decreased senescence markers in diabetic kidneys. In vitro, hidrosmin dose-dependently reduced the expression of inflammatory and oxidative genes in tubuloepithelial cells exposed to either high-glucose or cytokines, with no evidence of cytotoxicity at effective concentrations. In conclusion, the synthetic flavonoid hidrosmin exerts a beneficial effect against DN by reducing inflammation, oxidative stress, and senescence pathways. Hidrosmin could have a potential role as a coadjutant therapy for the chronic complications of DM.

Klotho protects against diabetic kidney disease via AMPK- and ERK-mediated autophagy

BACKGROUND

Diabetic kidney disease (DKD) is a serious complication of diabetes mellitus and results in serious public health problems. Although a great number of studies have been performed to elucidate the mechanisms of this disease, these mechanisms remain largely unknown.

METHODS

Cell and animal models were first constructed using human renal proximal tubule cells stimulated by high glucose (HG) and mice induced by streptozotocin (STZ). After Klotho overexpression, Klotho expression was assessed by RT-PCR and western blot, immunofluorescence; autophagy and AMPK/ERK proteins were confirmed using western blot or immunohistochemical assay; the autophagosomes were observed by transmission electron microscope; the pathological structure, fibrosis, polysaccharides and glycogen of kidney were evaluated by H&E staining, Masson staining and PAS staining.

RESULTS

We first confirmed that Klotho expression and autophagic activity were reduced in DM mice and HG-induced human renal proximal tubule cells. Besides, overexpression of Klotho could significantly enhance autophagy and AMPK and ERK1/2 activities in vivo and in vitro, which also could be abolished by selective AMPK inhibitor and ERK activator. Moreover, we proved that Klotho could inhibit hyperglycemia-induced renal tubular damage.

CONCLUSION

In summary, our results proved that Klotho improved renal tubular cell autophagy via the AMPK and ERK pathways and played a role in renal protection. These findings provide new insight into the mechanism of Klotho and autophagy in DKD.

Role of Cellular Senescence in Type II Diabetes

Cellular senescence is a cell fate that occurs in response to numerous types of stress and can promote tissue repair or drive inflammation and disruption of tissue homeostasis depending on the context. Aging and obesity lead to an increase in the senescent cell burden in multiple organs. Senescent cells release a myriad of senescence-associated secretory phenotype factors that directly mediate pancreatic β-cell dysfunction, adipose tissue dysfunction, and insulin resistance in peripheral tissues, which promote the onset of type II diabetes mellitus. In addition, hyperglycemia and metabolic changes seen in diabetes promote cellular senescence. Diabetes-induced cellular senescence contributes to various diabetic complications. Thus, type II diabetes is both a cause and consequence of cellular senescence. This review summarizes recent studies on the link between aging, obesity, and diabetes, focusing on the role of cellular senescence in disease processes.

The Role of Vascular Lesions in Diabetes Across a Spectrum of Clinical Kidney Disease

Introduction

The clinical-histologic correlation in diabetic nephropathy is not completely known.

Methods

We analyzed nephrectomy specimens from 90 patients with diabetes and diverse degrees of proteinuria and glomerular filtration rate (GFR).

Results

Thirty-six (40%) subjects had normoalbuminuria, 33 (37%) microalbuminuria, and 21 (23%) non-nephrotic proteinuria. Mean estimated GFR (eGFR) was 65±23 (40% <60 ml/min per 1.73 m²). About 170 glomeruli per patient were analyzed, and all samples included vascular tissue. Six subjects (7%) were classified in diabetic nephropathy class I, 61 (68%) in class II-a, 13 (14%) in class II-b, 9 (10%) class III, and 1 (1%) in class IV. Eighty percent to 90% of those with normoalbuminuria or microalbuminuria were classified in class II-a or II-b and <10% in class III; 52% of those with proteinuria were in class II-a, 15% in class II-b, and 19% in class III. Nodular sclerosis (57%) and mesangial expansion (15%) were more frequent in cases with proteinuria than in normoalbuminuria (28% and 8%; P = 0.028 and 0.017). About 20% to 30% of all cases, regardless the level of albuminuria or proteinuria or the histologic class had tubular atrophy, interstitial fibrosis, or inflammation in >10% to 20% of the sample. Moderate hyalinosis and arteriolar sclerosis were observed in 80% to 100% of cases with normoalbuminuria, microalbuminuria, proteinuria, as well as in class I, II, or III.

Conclusions

Weak correspondence between analytical parameters and kidney histology was found. Thus, disease may progress undetected from the early clinical stages of the disease. Finally, vascular damage was a very common finding, which highlights the role of ischemic intrarenal disease in diabetes.

Improving SIRT1 by trehalose supplementation reduces oxidative stress, inflammation, and histopathological scores in the kidney of aged rats

The aging process leads to progressive loss of kidney function. Sirtuin1 (SIRT1) exerts renoprotective effects by conferring resistance to cellular stresses. Trehalose potentially displayed various beneficial effects to promote health span. In this study, we investigated the effects of trehalose on renal SIRT1 and kidney function in senescent rats. Trehalose (2% w/v) was administrated in drinking water for 1 month to male aged rats (24 months). Then, the level of SIRT1 mRNA and protein, malondialdehyde, total antioxidant capacity, tumor necrosis factor α as well as parameters related to the function and histology of the kidneys were evaluated. Trehalose supplementation increased the level of SIRT1, whereas alleviated the level of oxidative stress, inflammation, and histopathology scores in senescent tissues. However, trehalose administration did not alter kidney function indices in old rats. Collectively, these findings suggested that trehalose was an effective intervention to ameliorate some aspects of age-associated injury in the old kidneys. PRACTICAL APPLICATIONS: Aging is associated with impairment in renal structure and function. Trehalose is a natural disaccharide, which is widely distributed in many organisms. The consumption of trehalose as a dietary supplement is increasing worldwide. This study showed that trehalose administration to aged rats had renoprotective effects through reducing oxidative stress and inflammation, which was mediated by SIRT1. Our results provide useful information for individuals using this sugar as a supplement.

Sirt3 promotes the autophagy of HK‑2 human proximal tubular epithelial cells via the inhibition of Notch‑1/Hes‑1 signaling

Diabetic nephropathy (DN) is a predominant cause of end-stage renal disease. The impairment of the autophagy of human renal tubular epithelial cells (HK-2 cells) is involved in the pathogenic mechanisms of DN. Sirtuin (Sirt)3 regulates the scavenging of damaged organelles and maintains energy balance. The present study aimed to examine the protective effects of Sirt3 on HK-2 cells stimulated by high glucose (HG). HK-2 cells were cultured in normal glucose (NG), HG or hyperosmotic medium. The viability of the HK-2 cells was detected using a Cell Counting Kit-8 assay. The expression and localization of Sirt3 were detected via immunofluorescence. Following transfection with an overexpression plasmid, the expression levels of key components in the Notch homolog 1 (Notch-1)/hairy and enhancer of split-1 (Hes-1) pathway and those of the autophagy-related proteins, Beclin-1, LC-3II and p62, were measured by western blot analysis and reverse transcription-quantitative PCR (RT-qPCR). As the Notch-1/Hes-1 pathway was inhibited, the expression levels of Beclin-1, LC-3II and p62 were also examined at transcriptional and translational level. It was found that prolonged culture in HG medium markedly reduced cell viability compared with the cells cultured in NG or in NG + mannitol, an effect that was aggravated with the increasing duration of culture. HG was capable of inhibiting the expression levels of Beclin-1, LC-3II and Sirt3, and upregulating p62 and the Notch-1/Hes-1 pathway, as verified by western blot analysis and RT-qPCR. The results of immunofluorescence staining revealed that HG decreased Sirt3 expression. Sirt3 reversed the HG-induced inhibition of the expression of Beclin-1 and LC-3II and the upregulation of p62. Moreover, Sirt3 reversed the HG-induced inhibition of the Notch-1/Hes-1 signaling pathway. However, this autophagy-promoting effect of Sirt3 was counteracted by the Notch-1/Hes-1 pathway activator. On the whole, the present study demonstrated that Sirt3 promoted the autophagy of HK-2 cells, at least partly, via the downregulation of Notch-1/Hes-1.

Biomarkers of Glyco-Metabolic Control in Hemodialysis Patients: Glycated Hemoglobin vs. Glycated Albumin

Background and Objectives: Glycated hemoglobin (HbA1c) dosage is considered the gold standard in glycol-metabolic monitoring, but it presents limits, which can underestimate the glycemia trend. In this regard, it was introduced the glycated albumin (GA). The aim of the study is to verify the predictivity of the GA compared to HbA1c in identifying glyco-metabolic alterations in non-diabetic and diabetic hemodialysis (HD) patients. Materials and Methods: For this purpose, we conducted a multicenter study involving one analysis laboratory and six dialysis centers in the Lazio region (Rome, Italy). Both diabetic and non-diabetic HD patients represent the study population, and the protocol included five time points. Results: The analyzed data highlighted the ability of GA to predict changes in glycemic metabolism in HD patients, and GA values are not significantly influenced, like HbA1c, by dialysis therapy itself and by comorbidities of the uremic state, such as normochromic and normocytic anemia. Thus, GA seems to reflect early glyco-metabolic alterations, both in patients with a previous diagnosis of diabetes and in subjects without diabetes mellitus. As part of this study, we analyzed two HD patients (one diabetic and one non-diabetic) in which GA was more predictive of glycol-metabolic alterations compared to HbA1c. Our study confirms the need to compare classical biomarkers used for the monitoring of glyco-metabolic alterations with new ones, likely more reliable and effective in specific subgroups of patients in which the classic biomarkers can be influenced by the preexisting pathological conditions. Conclusions: In conclusion, our evidence highlights that in uremic patients, GA shows a better ability to predict glyco-metabolic alterations allowing both an earlier diagnosis of DM and a prompt modulation of the hypoglycemic therapy, thus improving the clinical management of these patients.

Antiinflammatory Actions of Klotho: Implications for Therapy of Diabetic Nephropathy

Klotho was initially introduced as an antiaging molecule. Klotho deficiency significantly reduces lifespan, and its overexpression extends it and protects against various pathological phenotypes, especially renal disease. It was shown to regulate phosphate and calcium metabolism, protect against oxidative stress, downregulate apoptosis, and have antiinflammatory and antifibrotic properties. The course of diabetes mellitus and diabetic nephropathy resembles premature cellular senescence and causes the activation of various proinflammatory and profibrotic processes. Klotho was shown to exert many beneficial effects in these disorders. The expression of Klotho protein is downregulated in early stages of inflammation and diabetic nephropathy by proinflammatory factors. Therefore, its therapeutic effects are diminished in this disorder. Significantly lower urine levels of Klotho may serve as an early biomarker of renal involvement in diabetes mellitus. Recombinant Klotho administration and Klotho overexpression may have immunotherapeutic potential for the treatment of both diabetes and diabetic nephropathy. Therefore, the current manuscript aims to characterize immunopathologies occurring in diabetes and diabetic nephropathy, and tries to match them with antiinflammatory actions of Klotho. It also gives reasons for Klotho to be used in diagnostics and immunotherapy of these disorders.

Atorvastatin Regulates MALAT1/miR-200c/NRF2 Activity to Protect Against Podocyte Pyroptosis Induced by High Glucose

BACKGROUND

Diabetic nephropathy (DN) is one of the main complications of diabetes mellitus (DM), which leads to the long-term loss of kidney functions. Long noncoding RNAs (LncRNAs) can alleviate DN by interacting with microRNAs (miRNAs). In this work, we aimed to explore the effects of the MALAT1/miR-200c/NRF2 regulatory axis on the pyroptosis and oxidative stress (Oxidative stress, OS) of renal podocytes in high glucose (HG) environment and whether the lipid-lowering drug atorvastatin (AT) can relieve renal OS through this approach.

METHODS

MPC-5, a mouse podocyte cell line, was induced by HG as a cell model. The protein expressions of caspase-1, GSDMD, NLRP3, NRF2, etc. were detected by Western blotting and immunofluorescence, and the mRNA level of caspase-1, GSDMD, NLRP3, NRF2, MALAT1, miR-200c was tested by qRT-PCR. The cell pyroptosis of podocytes treated with AT was verified by CCK-8 or flow cytometry. The levels of Malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione (GSH) were measured by spectrophotometer, respectively.

RESULTS

The caspase-1 was upregulated in time-dependent manner and got the peak at 48 h and 30 mmol/L respectively in MPC-5 cells treated with HG. Further, the expression of GSDMD, MALAT1 and miR-200c were increased, while the level of NRF2, HO-1, OS-related indicators, were decreased simultaneously. Knockdown the MALAT1 protected MPC-5 cells from pyroptosis and OS induced by HG. However, overexpressing miR-200c in control-group cells increased pyroptosis and upregulated the OS level with HG culture medium. Further, atorvastatin protected MPC-5 cells from cell pyroptosis and downregulated the level of renal OS via attenuating the expression of MALAT1 and miR-200c.

CONCLUSION

Atorvastatin protects podocyte cells via MALAT1/miR-200c/NRF2 signal pathway from pyroptosis and OS induced by HG.