Renal Lipid Metabolism and Lipotoxicity in Diabetes

Lipid nephrotoxicity mediated by HIF-1α activation accelerates tubular injury in diabetic nephropathy

This study is intended to explore the effect of hypoxia-inducible factor-1α (HIF-1α) activation on lipid accumulation in the diabetic kidney. A type 1 diabetic rat model was established by STZ intraperitoneal injection. Cobalt chloride (CoCl2) and YC-1 were used as the HIF-1α activator and antagonist, respectively. CoCl2 treatment significantly increased HIF-1α expression, accelerated lipid deposition, and accelerated tubular injury in diabetic kidneys. In vitro, CoCl2 effectively stabilized HIF-1α and increased its transportation from the cytoplasm to the nucleus, which was accompanied by significantly increased lipid accumulation in HK-2 cells. Furthermore, results obtained in vivo showed that HIF-1α protein expression in the renal tubules of diabetic rats was significantly downregulated by YC-1 treatment. Meanwhile, lipid accumulation in the tubules of the DM + YC-1 group was markedly decreased in comparison to the DM + DMSO group. Accordingly, PAS staining revealed that the pathological injury caused to the tubular epithelial cells was alleviated by YC-1 treatment. Furthermore, the blood glucose level, urine albumin creatinine ratio, and NAG creatinine ratio in the DM + YC-1 group were significantly decreased compared to the DM + DMSO group. Moreover, the protein expression levels of transforming growth factor β1 (TGF-β1) and connective tissue growth factor (CTGF) in diabetic kidneys were decreased by YC-1 treatment. Our findings demonstrate that the activation of HIF-1α contributed to interstitial injury in a rat model of diabetic nephropathy and that the underlying mechanism involved the induction of lipid accumulation.

Estimated small dense low-density lipoprotein-cholesterol and the risk of kidney and cardiovascular outcomes in diabetic kidney disease

AIMS

This study aimed to investigate the correlations between estimated small dense low-density lipoprotein-cholesterol (esd-LDL-c) and the development of end-stage kidney disease (ESKD), cardiovascular mortality, and all-cause mortality in individuals with diabetic kidney disease (DKD) or diabetes mellitus (DM) concomitant chronic kidney disease (CKD).

METHODS

We analyzed the data from a biopsy-proven DKD cohort conducted at West China Hospital of Sichuan University between 2009 and 2021 (the DKD cohort) and participants with DM and CKD in the National Health and Nutrition Examination Survey (NHANES) 2011-2014 (the NHANES DM-CKD cohort). Cox regression analysis was also used to estimate associations between esd-LDL-c and the incidence of ESKD, cardiovascular mortality, and all-cause mortality.

RESULTS

There were 175 ESKD events among 338 participants in the DKD cohort. Patients were divided into three groups based on esd-LDL-c tertiles (T1 < 33.7 mg/dL, T2 ≥ 33.7 mg/dL to <45.9 mg/dL, T3 ≥ 45.9 mg/dL). The highest tertile of esd-LDL-c was associated with ESKD (adjusted HR 2.016, 95% CI 1.144-3.554, p = .015). Furthermore, there were 99 deaths (39 cardiovascular) among 293 participants in the NHANES DM-CKD cohort. Participants were classified into three groups in line with the tertile values of esd-LDL-c in the DKD cohort. The highest tertile of esd-LDL-c was associated with cardiovascular mortality (adjusted HR 3.95, 95% CI 1.3-12, p = .016) and all-cause mortality (adjusted HR 2.37, 95% CI 1.06-5.32, p = .036).

CONCLUSIONS

Higher esd-LDL-c was associated with increased risk of ESKD in people with biopsy-proven DKD, and higher cardiovascular and all-cause mortality risk among those with DM-CKD.

Elevated ALOX12 in renal tissue predicts progression in diabetic kidney disease

Diabetic kidney disease (DKD) is one of the major causes of end-stage renal disease and one of the significant complications of diabetes. This study aims to identify the main differentially expressed genes in DKD from transcriptome sequencing results and analyze their diagnostic value. The present study sequenced db/m mouse and db/db mouse to determine the ALOX12 genetic changes related to DKD. After preliminary validation, ALOX12 levels were significantly elevated in the blood of DKD patients, but not during disease progression. Moreover, urine ALOX12 was increased only in macroalbuminuria patients. Therefore, to visualize the diagnostic efficacy of ALOX12 on the onset and progression of renal injury in DKD, we collected kidney tissue from patients for immunohistochemical staining. ALOX12 was increased in the kidneys of patients with DKD and was more elevated in macroalbuminuria patients. Clinical chemical and pathological data analysis indicated a correlation between ALOX12 protein expression and renal tubule injury. Further immunofluorescence double staining showed that ALOX12 was expressed in both proximal tubules and distal tubules. Finally, the diagnostic value of the identified gene in the progression of DKD was assessed using receiver operating characteristic (ROC) curve analysis. The area under the curve (AUC) value for ALOX12 in the diagnosis of DKD entering the macroalbuminuria stage was 0.736, suggesting that ALOX12 has good diagnostic efficacy. During the development of DKD, the expression levels of ALOX12 in renal tubules were significantly increased and can be used as one of the predictors of the progression to macroalbuminuria in patients with DKD.

Molecular mechanism of renal lipid accumulation in diabetic kidney disease

Diabetic kidney disease (DKD) is a leading cause of end stage renal disease with unmet clinical demands for treatment. Lipids are essential for cell survival; however, renal cells have limited capability to metabolize overloaded lipids. Dyslipidaemia is common in DKD patients and renal ectopic lipid accumulation is associated with disease progression. Unveiling the molecular mechanism involved in renal lipid regulation is crucial for exploring potential therapeutic targets. In this review, we focused on the mechanism underlying cholesterol, oxysterol and fatty acid metabolism disorder in the context of DKD. Specific regulators of lipid accumulation in different kidney compartment and TREM2 macrophages, a lipid-related macrophages in DKD, were discussed. The role of sodium-glucose transporter 2 inhibitors in improving renal lipid accumulation was summarized.

Functional interplay of lipid droplets and mitochondria

Our body stores energy mostly in form of fatty acids (FAs) in lipid droplets (LDs). From there the FAs can be mobilized and transferred to peroxisomes and mitochondria. This transfer is dependent on close opposition of LDs and mitochondria and peroxisomes and happens at membrane contact sites. However, the composition and the dynamics of these contact sites is not well understood, which is in part due to the dependence on the metabolic state of the cell and on the cell- and tissue-type. Here, we summarize the current knowledge on the contacts between lipid droplets and mitochondria both in mammals and in the yeast Saccharomyces cerevisiae, in which various contact sites are well studied. We discuss possible functions of the contact site and their implication in disease.

Are we ready for an adipocentric approach in people living with type 2 diabetes and chronic kidney disease?

We are entering a new era in the management of adiposity-based chronic disease (ABCD) with type 2 diabetes (T2D) and related chronic kidney disease (CKD). ABCD, T2D and CKD can affect almost every major organ system and have a particularly strong impact on the incidence of cardiovascular disease (CVD) and heart failure. ABCD and the associated insulin resistance are at the root of many cardiovascular, renal and metabolic (CKM) disorders, thus an integrated therapeutic framework using weight loss (WL) as a disease-modifying intervention could simplify the therapeutic approach at different stages across the lifespan. The breakthrough of highly effective WL drugs makes achieving a WL of >10% possible, which is required for a potential T2D disease remission as well as for prevention of microvascular disease, CKD, CVD events and overall mortality. The aim of this review is to discuss the link between adiposity and CKM conditions as well as placing weight management at the centre of the holistic CKM syndrome approach with a focus on CKD. We propose the clinical translation of the available evidence into a transformative Dysfunctional Adipose Tissue Approach (DATA) for people living with ABCD, T2D and CKD. This model is based on the interplay of four essential elements (i.e. adipocentric approach and target organ protection, dysfunctional adiposity, glucose homeostasis, and lifestyle intervention and de-prescription) together with a multidisciplinary person-centred care. DATA could facilitate decision-making for all clinicians involved in the management of these individuals, and if we do this in a multidisciplinary way, we are prepared to meet the adipocentric challenge.

Wistar rat as an animal model to study high-fat induced kidney damage: a systematic review

The effects of high-fat-associated kidney damage in humans are not completely elucidated. Animal experiments are essential to understanding the mechanisms underlying human diseases. This systematic review aimed to compile evidence of the role of a high-fat diet during the development of renal lipotoxicity and fibrosis of Wistar rats to understand whether this is a satisfactory model for the study of high fat-induced kidney damage. We conducted systematic searches in PUBMED, EMBASE, Lilacs, and Web of Science databases from inception until May 2021. The risk of bias was assessed using SYRCLE toll. Two reviewers independently screened abstracts and reviewed full-text articles. A total of 11 studies were included. The damage varied depending on the age and sex of the animals, time of protocol, and amount of fat in the diet. In conclusion, the Wistar rat is an adequate animal model to assess the effects of a high-fat diet on the kidneys.HighlightsA high-fat diet may promote kidney damage in Wistar rats.Wistar rat is efficient as an animal model to study high-fat-induced kidney damage.The effect of the diet depends on the fat amount, consumption time, and animal age.

Bioorthogonal photocatalytic proximity labeling in primary living samples

In situ profiling of subcellular proteomics in primary living systems, such as native tissues or clinic samples, is crucial for understanding life processes and diseases, yet challenging due to methodological obstacles. Here we report CAT-S, a bioorthogonal photocatalytic chemistry-enabled proximity labeling method, that expands proximity labeling to a wide range of primary living samples for in situ profiling of mitochondrial proteomes. Powered by our thioQM labeling warhead development and targeted bioorthogonal photocatalytic chemistry, CAT-S enables the labeling of mitochondrial proteins in living cells with high efficiency and specificity. We apply CAT-S to diverse cell cultures, dissociated mouse tissues as well as primary T cells from human blood, portraying the native-state mitochondrial proteomic characteristics, and unveiled hidden mitochondrial proteins (PTPN1, SLC35A4 uORF, and TRABD). Furthermore, CAT-S allows quantification of proteomic perturbations on dysfunctional tissues, exampled by diabetic mouse kidneys, revealing the alterations of lipid metabolism that may drive disease progression. Given the advantages of non-genetic operation, generality, and spatiotemporal resolution, CAT-S may open exciting avenues for subcellular proteomic investigations of primary samples that are otherwise inaccessible.

N6-methyladenosine RNA methylation in diabetic kidney disease

Diabetic kidney disease (DKD) is a major microvascular complication of diabetes, and hyperglycemic memory associated with diabetes carries the risk of disease occurrence, even after the termination of blood glucose injury. The existence of hyperglycemic memory supports the concept of an epigenetic mechanism involving n6-methyladenosine (m6A) modification. Several studies have shown that m6A plays a key role in the pathogenesis of DKD. This review addresses the role and mechanism of m6A RNA modification in the progression of DKD, including the regulatory role of m6A modification in pathological processes, such as inflammation, oxidative stress, fibrosis, and non-coding (nc) RNA. This reveals the importance of m6A in the occurrence and development of DKD, suggesting that m6A may play a role in hyperglycemic memory phenomenon. This review also discusses how some gray areas, such as m6A modified multiple enzymes, interact to affect the development of DKD and provides countermeasures. In conclusion, this review enhances our understanding of DKD from the perspective of m6A modifications and provides new targets for future therapeutic strategies. In addition, the insights discussed here support the existence of hyperglycemic memory effects in DKD, which may have far-reaching implications for the development of novel treatments. We hypothesize that m6A RNA modification, as a key factor regulating the development of DKD, provides a new perspective for the in-depth exploration of DKD and provides a novel option for the clinical management of patients with DKD.

Fatty acids and inflammatory stimuli induce expression of long-chain acyl-CoA synthetase 1 to promote lipid remodeling in diabetic kidney disease

Fatty acid handling and complex lipid synthesis are altered in the kidney cortex of diabetic patients. We recently showed that inhibition of the renin-angiotensin system without changes in glycemia can reverse diabetic kidney disease (DKD) and restore the lipid metabolic network in the kidney cortex of diabetic (db/db) mice, raising the possibility that lipid remodeling may play a central role in DKD. However, the roles of specific enzymes involved in lipid remodeling in DKD have not been elucidated. In the present study, we used this diabetic mouse model and a proximal tubule epithelial cell line (HK2) to investigate the potential relationship between long-chain acyl-CoA synthetase 1 (ACSL1) and lipid metabolism in response to fatty acid exposure and inflammatory signals. We found ACSL1 expression was significantly increased in the kidney cortex of db/db mice, and exposure to palmitate or tumor necrosis factor-α significantly increased Acsl1 mRNA expression in HK-2 cells. In addition, palmitate treatment significantly increased the levels of long-chain acylcarnitines and fatty acyl CoAs in HK2 cells, and these increases were abolished in HK2 cell lines with specific deletion of Acsl1(Acsl1KO cells), suggesting a key role for ACSL1 in fatty acid β-oxidation. In contrast, tumor necrosis factor-α treatment significantly increased the levels of short-chain acylcarnitines and long-chain fatty acyl CoAs in HK2 cells but not in Acsl1KO cells, consistent with fatty acid channeling to complex lipids. Taken together, our data demonstrate a key role for ACSL1 in regulating lipid metabolism, fatty acid partitioning, and inflammation.

Global research trends and hot spots on autophagy and kidney diseases: a bibliometric analysis from 2000 to 2022

Background: Autophagy is an essential cellular process involving the self-degradation and recycling of organelles, proteins, and cellular debris. Recent research has shown that autophagy plays a significant role in the occurrence and development of kidney diseases. However, there is a lack of bibliometric analysis regarding the relationship between autophagy and kidney diseases. Methods: A bibliometric analysis was conducted by searching for literature related to autophagy and kidney diseases in the Web of Science Core Collection (WoSCC) database from 2000 to 2022. Data processing was carried out using R package "Bibliometrix", VOSviewers, and CiteSpace. Results: A total of 4,579 articles related to autophagy and kidney diseases were collected from various countries. China and the United States were the main countries contributing to the publications. The number of publications in this field showed a year-on-year increasing trend, with open-access journals playing a major role in driving the literature output. Nanjing Medical University in China, Osaka University in Japan, and the University of Pittsburgh in the United States were the main research institutions. The journal "International journal of molecular sciences" had the highest number of publications, while "Autophagy" was the most influential journal in the field. These articles were authored by 18,583 individuals, with Dong, Zheng; Koya, Daisuke; and Kume, Shinji being the most prolific authors, and Dong, Zheng being the most frequently co-cited author. Research on autophagy mainly focused on diabetic kidney diseases, acute kidney injury, and chronic kidney disease. "Autophagy", "apoptosis", and "oxidative stress" were the primary research hotspots. Topics such as "diabetic kidney diseases", "sepsis", "ferroptosis", "nrf2", "hypertension" and "pi3k" may represent potential future development trends. Research on autophagy has gradually focused on metabolic-related kidney diseases such as diabetic nephropathy and hypertension. Additionally, PI3K, NRF2, and ferroptosis have been recent research directions in the field of autophagy mechanisms. Conclusion: This is the first comprehensive bibliometric study summarizing the relationship between autophagy and kidney diseases. The findings aid in identifying recent research frontiers and hot topics, providing valuable references for scholars investigating the role of autophagy in kidney diseases.

Direct androgen receptor control of sexually dimorphic gene expression in the mammalian kidney

Mammalian organs exhibit distinct physiology, disease susceptibility, and injury responses between the sexes. In the mouse kidney, sexually dimorphic gene activity maps predominantly to proximal tubule (PT) segments. Bulk RNA sequencing (RNA-seq) data demonstrated that sex differences were established from 4 and 8 weeks after birth under gonadal control. Hormone injection studies and genetic removal of androgen and estrogen receptors demonstrated androgen receptor (AR)-mediated regulation of gene activity in PT cells as the regulatory mechanism. Interestingly, caloric restriction feminizes the male kidney. Single-nuclear multiomic analysis identified putative cis-regulatory regions and cooperating factors mediating PT responses to AR activity in the mouse kidney. In the human kidney, a limited set of genes showed conserved sex-linked regulation, whereas analysis of the mouse liver underscored organ-specific differences in the regulation of sexually dimorphic gene expression. These findings raise interesting questions on the evolution, physiological significance, disease, and metabolic linkage of sexually dimorphic gene activity.

Regulation of renal lipid deposition in diabetic nephropathy on morroniside via inhibition of NF-KB/TNF-a/SREBP1c signaling pathway

Morroniside (MOR), a cyclic enol ether terpene glycoside isolated from Cornus officinalis, has been shown to inhibit lipid accumulation, although the mechanism of action is uncertain. The aim of this study was to investigate the potential pathways by which MOR affects renal lipid deposition in diabetic nephropathy (DN). In vitro and in vivo experiments were performed using the PA-induced HK-2 cell model and a KKAy animal model, respectively. Network pharmacological analysis was used to identify potential MOR signaling pathways for DN therapy, with results verified via Western blotting and immunofluorescence experiments. The effect of MOR on lipid metabolism was investigated using BODIPY 493/503 staining. Our results indicate that MOR significantly reduces lipid accumulation both in vitro and in vivo. According to network pharmacology studies, the NF-κB/TNF-α/SREBP1c signaling pathway may be the mechanism of action of MOR in DN. MOR was found to inhibit this pathway by reducing the phosphorylation of NF-κB p65 and the expression of TNF-α and SREBP1c, similar to the effects of Bay11-7082. Additionally, MOR significantly inhibited the expression of lipid factors such as ACC, FAS, and SCD1. In conclusion, MOR can regulate the disruption of lipid metabolism in DN and reduce renal lipid deposition via suppression of the NF-κB/TNF-α/SREBP1c signaling pathway.

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.

Mulberry leaf extract and neochlorogenic acid ameliorate glucolipotoxicity-induced diabetic nephropathy in high-fat diet-fed db/db mice

Diabetic nephropathy, a major diabetes complication, is often exacerbated by glucolipotoxicity. The potential benefits of mulberry leaf extract (MLE) and its primary component, neochlorogenic acid (nCGA), in combating this condition have not been extensively explored. High-fat diet-fed db/db mice were employed as a model for glucolipotoxicity-induced diabetic nephropathy. The mice were treated with MLE or nCGA, and their body weight, insulin sensitivity, blood lipid profiles, and kidney function were assessed. In addition, modulation of the JAK-STAT, pAKT, Ras, and NF-κB signaling pathways by MLE and nCGA was evaluated. MLE and nCGA did not significantly decrease blood glucose level but effectively mitigated the adverse effects of a high-fat diet on blood lipid profile and kidney function. Improvements in body weight, insulin sensitivity, and kidney structure, along with a reduction in fibrosis, were observed. Both MLE and nCGA regulated lipid metabolism abnormalities, significantly inhibited the accumulation of glycosylated substances in glomeruli, and modulated crucial signaling pathways involved in diabetic nephropathy. Although they do not directly affect blood glucose level, MLE and nCGA show significant potential in managing glucolipotoxicity-induced diabetic nephropathy by targeting lipid metabolism and key molecular pathways. The present findings suggest MLE and nCGA may be promising therapeutic agents for diabetic nephropathy, and further exploration in human patients is warranted.

Tubular injury in diabetic kidney disease: molecular mechanisms and potential therapeutic perspectives

Diabetic kidney disease (DKD) is a chronic complication of diabetes and the leading cause of end-stage renal disease (ESRD) worldwide. Currently, there are limited therapeutic drugs available for DKD. While previous research has primarily focused on glomerular injury, recent studies have increasingly emphasized the role of renal tubular injury in the pathogenesis of DKD. Various factors, including hyperglycemia, lipid accumulation, oxidative stress, hypoxia, RAAS, ER stress, inflammation, EMT and programmed cell death, have been shown to induce renal tubular injury and contribute to the progression of DKD. Additionally, traditional hypoglycemic drugs, anti-inflammation therapies, anti-senescence therapies, mineralocorticoid receptor antagonists, and stem cell therapies have demonstrated their potential to alleviate renal tubular injury in DKD. This review will provide insights into the latest research on the mechanisms and treatments of renal tubular injury in DKD.

Association between GLP-1R gene polymorphism and dyslipidemia in Chinese patients with type 2 diabetes mellitus: a case-control study

OBJECTIVE

To evaluate the relationship between GLP-1R gene polymorphisms and type 2 diabetes mellitus with dyslipidemia and without dyslipidemia in China.

METHODS

A total of 200 patients with Type 2 Diabetes Mellitus (T2DM) were included in this study, including 115 with dyslipidemia and 85 without dyslipidemia. We used Sanger double deoxygenation terminal assay and PCR-RFLP to detect genotype of the GLP-1R rs10305420 and rs3765467 loci. T-test was used to analyze the association between gene polymorphisms and lipid indicators. SHEsis online analysis software was used to analyze the linkage balance effect of loci, and SPSS 26 was used to calculate the gene interaction by dominant model.

RESULTS

The genotype distribution of the two loci in the sample of this study was in accordance with Hardy-weinberg equilibrium. There were significant differences in the genotype distribution and allele frequency of rs3765467 between T2DM patients with and without dyslipidemia (GG 52.9%, GA+AA 47.1% vs. GG 69.6%, GA+AA 30.4%; P = 0.017). Under the dominant model, the effects of rs3765467 A allele and rs10305420 T allele on dyslipidemia had multiplicative interactions (P = 0.016) and additive interactions (RERI = 0.403, 95% CI [-2.708 to 3.514]; AP = 0.376, 95% CI [-2.041, 2.793]). Meanwhile, HbA_1c levels in rs3765467 A allele carriers (GA+AA) were found to be significantly lower than those in patients with GG genotype (P = 0.006).

CONCLUSION

The rs3765467 (G/A) variant is associated with the incidence of dyslipidemia, and G allele may be a risk factor for dyslipidemia.

The association and prediction value of acylcarnitine on diabetic nephropathy in Chinese patients with type 2 diabetes mellitus

BACKGROUND

Acylcarnitines play a role in type 2 diabetes mellitus (T2DM), but the relationship between acylcarnitine and diabetic nephropathy was unclear. We aimed to explore the association of acylcarnitine metabolites with diabetic nephropathy and estimate the predictive value of acylcarnitine for diabetic nephropathy.

METHODS

A total of 1032 (mean age: 57.24 ± 13.82) T2DM participants were derived from Liaoning Medical University First Affiliated Hospital. Mass Spectrometry was utilized to measure levels of 25 acylcarnitine metabolites in fasting plasma. Diabetic nephropathy was ascertained based on the medical records. Factor analysis was used to reduce the dimensions and extract factors of the 25 acylcarnitine metabolites. Logistic regression was used to estimate the relationship between factors extracted from the 25 acylcarnitine metabolites and diabetic nephropathy. Receiver operating characteristic curves were used to test the predictive values of acylcarnitine factors for diabetic nephropathy.

RESULTS

Among all T2DM participants, 138 (13.37%) patients had diabetic nephropathy. Six factors were extracted from 25 acylcarnitines, which account for 69.42% of the total variance. In multi-adjusted logistic regression models, the odds ratio (OR, 95% confidence interval [CI]) of diabetic nephropathy on factor 1 (including butyrylcarnitine/glutaryl-carnitine/hexanoylcarnitine/octanoylcarnitine/decanoylcarnitine/lauroylcarnitine/tetradecenoylcarnitine), factor 2 (including propionylcarnitine/palmitoylcarnitine/hydroxypalmitoleyl-carnitine/octadecanoylcarnitine/arachidiccarnitine), and factor 3 (including tetradecanoyldiacylcarnitine/behenic carnitine/tetracosanoic carnitine/hexacosanoic carnitine) were 1.33 (95%CI 1.12-1.58), 0.76 (95%CI 0.62-0.93), and 1.24 (95%CI 1.05-1.47), respectively. The area under the curve for diabetic nephropathy prediction was significantly increased after the complement of factors 1, 2, and 3 in traditional factors model (P < 0.01).

CONCLUSIONS

Some plasma acylcarnitine metabolites extracted in factors 1 and 3 were higher in diabetic nephropathy, while factor 2 was lower in diabetic nephropathy among T2DM patients. The addition of acylcarnitine to traditional factors model improved the predictive value for diabetic nephropathy.

Direct androgen receptor regulation of sexually dimorphic gene expression in the mammalian kidney

Mammalian organs exhibit distinct physiology, disease susceptibility and injury responses between the sexes. In the mouse kidney, sexually dimorphic gene activity maps predominantly to proximal tubule (PT) segments. Bulk RNA-seq data demonstrated sex differences were established from 4 and 8 weeks after birth under gonadal control. Hormone injection studies and genetic removal of androgen and estrogen receptors demonstrated androgen receptor (AR) mediated regulation of gene activity in PT cells as the regulatory mechanism. Interestingly, caloric restriction feminizes the male kidney. Single-nuclear multiomic analysis identified putative cis-regulatory regions and cooperating factors mediating PT responses to AR activity in the mouse kidney. In the human kidney, a limited set of genes showed conserved sex-linked regulation while analysis of the mouse liver underscored organ-specific differences in the regulation of sexually dimorphic gene expression. These findings raise interesting questions on the evolution, physiological significance, and disease and metabolic linkage, of sexually dimorphic gene activity.

Renal metabolomic profiling of large yellow croaker Larimichthys crocea acclimated in low salinity waters

Cultivation of Larimichthys crocea in low salinity water has been regarded as an effective way to treat diseases induced by pathogens in seawater. The kidney of euryhaline teleost plays important roles in not only osmoregulation but also regulation of intermediary metabolism. However, the renal responses of metabolism and osmoregulation in L. crocea to low salinity waters are still rarely reported. In this work, renal metabolomic analysis based on MS technique was conducted on the L. crocea following cultivation in salinities of 24, 8, 6, 4, and 2 ppt for 40 days. A total of 485 metabolites covering organic acids and derivatives (34.17 %), lipids and lipid-like molecules (17.55 %), organoheterocyclic compounds (12.22 %), nucleosides, nucleotides, and analogues (11.91 %), and organic oxygen compounds (10.97 %), were identified in L. crocea kidney. Compared with control group (salinity 24), nearly all amino acids, nucleotides, and their derivatives were decreased in the kidney of L. crocea, whereas most of lipid-related metabolites including phospholipid, glycerophospholipids, and fatty acids were increased. The decrease in urea and inorganic ions as well as TMAO, betaine and taurine in L. crocea kidney suggested the less demand for maintaining osmotic homeostasis. Several intermediary metabolites covering amino acids, TCA cycle intermediates, and fatty acids were also significantly changed to match with the shift of energy allocation from osmoregulation to other biological processes. The reduced energy demand for osmoregulation might contribute to the promotion of L. crocea growth under low salinity environment. What is more, carbamoylphosphate and urea that showed linear salinity response curves and higher ED₅₀ values were potential biomarkers to adaptation to low salinity water. Overall, the characterization of metabolomes of L. crocea kidney under low salinity provided a better understanding of the adaptive mechanisms to low salinity water and potentially contributed to a reference for optimal culture salinity and feed formula of L. crocea culture in low salinity water.

Preliminary study of the interactive effects of coronary heart disease and lacunar infarction on renal function in patients with type 2 diabetes mellitus by gender

BACKGROUND

Coronary heart disease (CHD) and lacunar infarction (LI) are the most common cardio- cerebrovascular complications of type 2 diabetes mellitus (T2DM) and a recognized risk factor for renal injury. Although a unidirectional association of CHD or LI with T2DM or the kidney has been demonstrated, however, it remains unknown whether there is an interactive effect of the coexistence of CHD and LI on renal function in T2DM patients. The aim of our study was to investigate the interaction between CHD and LI on renal function in gender-specific patients with T2DM and the association between cardio-cerebrovascular disease-related conventional serum markers and the estimated glomerular filtration rate (eGFR).

METHODS

We conducted a cross-sectional study in Beijing and Tianjin from April 2019 to August 2021. Participants with T2DM aged ≥18 years were asked to complete a one-to-one questionnaire and physical examination.

RESULTS

In this study, 389 eligible patients with T2DM were included, with a mean age of 63.04 ± 9.41 years, of whom 200 (51.41 %) were male. The proportions of patients with CHD, LI, and both CHD and LI were 28.53 %, 24.42 %, and 11.05 %, respectively. Compared to T2DM patients without either CHD or LI, those with both CHD and LI were found to have a significantly greater risk of reduced eGFR (OR: 12.82, 95 % CI 5.06-32.52, P < 0.001) than those with CHD alone (OR: 2.42, 95 % CI 1.37-3.00, P = 0.004) or LI alone (OR: 1.15, 95 % CI 0.61-2.18, P = 0.664). The combined presence of CHD and LI is associated with a significantly greater risk of decreased eGFR in female T2DM patients compared to their male counterparts. We found both multiplicative and additive effects in all T2DM patients; however, when stratified by sex, only multiplicative effects were observed. After controlling for interference from CHD, LI, and age, we found that total cholesterol (TC) was negatively correlated with eGFR in females (r = -0.156, P = 0.034), and low-density lipoprotein cholesterol (LDL-C) was negatively correlated with eGFR in males (r = -0.229, P = 0.001).

CONCLUSION

This study provides novel evidence that the synergistic effect of CHD and LI on renal injury in patients with T2DM is significantly greater than their individual effects. Women with T2DM who have both CHD and LI are at a 4.85-fold higher risk of decreased eGFR than men. Therefore, increased clinical attention should be given to preventing and treating vascular complications in T2DM patients, as well as aggressively reducing lipid levels, particularly TC and LDL-C, to delay or prevent renal dysfunction in T2DM patients.

Inhibition of Fatty Acid β-Oxidation by Fatty Acid Binding Protein 4 Induces Ferroptosis in HK2 Cells Under High Glucose Conditions

BACKGRUOUND

Ferroptosis, which is caused by an iron-dependent accumulation of lipid hydroperoxides, is a type of cell death linked to diabetic kidney disease (DKD). Previous research has shown that fatty acid binding protein 4 (FABP4) is involved in the regulation of ferroptosis in diabetic retinopathy. The present study was constructed to explore the role of FABP4 in the regulation of ferroptosis in DKD.

METHODS

We first detected the expression of FABP4 and proteins related to ferroptosis in renal biopsies of patients with DKD. Then, we used a FABP4 inhibitor and small interfering RNA to investigate the role of FABP4 in ferroptosis induced by high glucose in human renal proximal tubular epithelial (HG-HK2) cells.

RESULTS

In kidney biopsies of DKD patients, the expression of FABP4 was elevated, whereas carnitine palmitoyltransferase-1A (CP-T1A), glutathione peroxidase 4, ferritin heavy chain, and ferritin light chain showed reduced expression. In HG-HK2 cells, the induction of ferroptosis was accompanied by an increase in FABP4. Inhibition of FABP4 in HG-HK2 cells changed the redox state, sup-pressing the production of reactive oxygen species, ferrous iron (Fe2+), and malondialdehyde, increasing superoxide dismutase, and reversing ferroptosis-associated mitochondrial damage. The inhibition of FABP4 also increased the expression of CPT1A, reversed lipid deposition, and restored impaired fatty acid β-oxidation. In addition, the inhibition of CPT1A could induce ferroptosis in HK2 cells.

CONCLUSION

Our results suggest that FABP4 mediates ferroptosis in HG-HK2 cells by inhibiting fatty acid β-oxidation.

Metformin mitigates renal dysfunction in obese insulin-resistant rats via activation of the AMPK/PPARα pathway

Insulin signaling and lipid metabolism are disrupted by long-term consumption of a high-fat diet (HFD). This disruption can lead to insulin resistance, dyslipidemia and subsequently renal dysfunction as a consequence of the inactivation of the AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor-α (PPARα) or AMPK/PPARα pathways. We investigated the impact of metformin on the prevention of renal dysfunction through the modulation of AMPK-regulated PPARα-dependent pathways in insulin-resistant rats induced by a HFD. Male Wistar rats were fed a HFD for 16 weeks to induce insulin resistance. After insulin resistance had been confirmed, metformin (30 mg/kg) or gemfibrozil (50 mg/kg) was given orally for 8 weeks. Evidence of insulin resistance, dyslipidemia, lipid accumulation and kidney injury were observed in HF rats. Impairment of lipid oxidation, energy metabolism and renal organic anion transporter 3 (Oat3) expression and function were demonstrated in HF rats. Metformin can stimulate the AMPK/PPARα pathways and suppress sterol regulatory element-binding transcription factor 1 (SREBP1) and fatty acid synthase (FAS) signaling (SREBP1/FAS) to enable the regulation of lipid metabolism. Renal inflammatory markers and renal fibrosis expression induced by a HFD were more effectively reduced after metformin treatment than after gemfibrozil treatment. Interestingly, renal Oat3 function and expression and kidney injury were improved following metformin and gemfibrozil treatment. Renal cluster of differentiation 36 (CD36) or sodium glucose cotransporter type 2 (SGLT2) expression did not differ after treatment with metformin or gemfibrozil. Metformin and gemfibrozil could reduce the impairment of renal injury in obese conditions induced by a HFD through the AMPK/PPARα-dependent pathway. Interestingly, metformin demonstrated greater efficacy than gemfibrozil in attenuating renal lipotoxicity through the AMPK-regulated SREBP1/FAS signaling pathway.

Integrating metabolomics and network pharmacology to investigate Panax japonicus prevents kidney injury in HFD/STZ-induced diabetic mice

ETHNOPHARMACOLOGICAL RELEVANCE

Panax japonicus C. A. Meye (PJ) has unique effects on diseases by "qi" stagnation and blood stasis in ancient. Modern studies have shown that PJ can treat diabetic kidney disease (DKD) caused by deficiency and blood stasis.

AIM OF THE STUDY

This study evaluated the potential effects of PJ on DKD, a microvascular complication, and investigated its possible mechanisms.

MATERIALS AND METHODS

In this study, the chemical constituents of PJ were analyzed by HPLC. In vivo studies, we constructed a diabetic mice model by HDF combined with STZ, then administered PJ to diabetic mice for 6 weeks. Blood lipid, BUN, 24h urine protein, and renal tissue HE staining were detected to comprehensively evaluate the protective effect of PJ on DKD. Metabolomics investigated the metabolic pathways influenced by PJ in the treatment of DKD. Moreover, the potential targets and signal pathways were investigated using network pharmacology. Finally, molecular docking predicts affinity of active compounds and core targets, and western blotting was used to detect core target expression levels.

RESULTS

In vivo study, PJ can reduce hyperlipidemia, serum BUN, and 24-h urinary protein in diabetic mice, and protect the pathological changes in renal tissue. Metabolomics results showed that PJ had significant regulatory effect on unsaturated fatty acids, glycerophospholipid metabolism, and purine metabolism. Network pharmacology showed that MAPK1, MAPK8, Bcl-2, and Caspase 3 were the core targets in PJ against DKD. Molecular docking revealed that Bcl-2 and Caspase 3 have a strong affinity for Chikusetsusaponin Iva, Ginsenoside Rb1, and Ginsenoside Rg1. Moreover, when compared to the model group, the PJ group had higher levels of anti-apoptosis protein Bcl-2 and lower levels of pro-apoptosis protein Caspase 3.

CONCLUSION

PJ can reduce blood lipids, regulate the biosynthesis of unsaturated fatty acids and purine metabolism, thereby alleviating the renal injury of diabetic mice. Moreover, it can regulate the Bcl-2/caspase 3 apoptosis signaling pathway to prevent the apoptosis of renal cells and protect the renal function of diabetic mice.

Resistant starch from black rice, Oryza sativa L. var. ameliorates renal inflammation, fibrosis and injury in insulin resistant rats

It has recently been reported that black rice (BR) extract has anti-obesity, anti-diabetic, and anti-osteoporosis effects. It has been shown to reduce obese-related kidney dysfunction in animal models. This study aimed to investigate the effect of resistant starch from BR (RS) on renal inflammation, oxidative stress, and apoptosis in obese insulin resistant rats. Male Wistar rats were divided into six groups: normal diet (ND), ND treated with 150 mg of RS (NDRS150), high-fat (HF) diet, HF treated with 100 and 150 mg of RS (HFRS100), (HFRS150), and HF treated with metformin as a positive control. Insulin resistance was shown in the HF rats by glucose intolerance, increased insulin, total area under the curve of glucose and homeostasis model assessment of insulin resistance and dyslipidemia. The resulting metabolic disturbance in the HF rats caused renal inflammation, fibrosis and apoptosis progressing to kidney injury and dysfunction. Prebiotic RS including anthocyanin from BR at doses of 100 and 150 mg ameliorated insulin resistance, dyslipidemia and liver injury. Treatment with RS reduced TGF-β fibrotic and apoptotic pathways by inhibition of NF-κB and inflammatory cytokines which potentially restore kidney damage and dysfunction. In conclusion, prebiotic RS from BR ameliorated obesity induced renal injury and dysfunction by attenuating inflammatory, fibrotic, and apoptotic pathways in insulin resistant rats induced by HF.

Influence of Flavonoid-Rich Fraction of Monodora tenuifolia Seed Extract on Blood Biochemical Parameters in Streptozotocin-Induced Diabetes Mellitus in Male Wistar Rats

Diabetes mellitus is a metabolic disorder caused by either the total destruction of the pancreatic beta cells that secrete insulin for the uptake of glucose from the circulation or as a result of the inability of body cells to respond to the presence of insulin in the blood. The present study investigated the effect of a flavonoid-rich fraction of Monodora tenuifolia seed extract (FFMTSE) on blood parameters in streptozotocin (STZ)-induced diabetic male Wistar rats. The rats were divided into seven groups (n = 6). Group 1: normal control rats, Group 2: rats + FFMTSE (25 mg/kgbwt), Group 3: rats + FFMTSE (50 mg/kgbwt), Group 4: diabetic control rats, Group 5: diabetic rats + FFMTSE (25 mg/kgbwt), Group 6: diabetic rats + FFMTSE (50 mg/kgbwt), and Group 7: diabetic rats + Metformin. The assessment of the lipid profile, kidney functions (urea and creatinine), and cardiac biomarkers (LDH and CK-MB) were carried out in the plasma using established protocols. The results showed a significant increase in the concentrations of triacylglycerol, cholesterol, LDL-cholesterol, VLDL-cholesterol, urea, and creatinine, as well as in cardiac enzyme activities in diabetic rats. However, the administration of the FFMTSE significantly improved the observed biochemical parameters. In addition, an increased concentration of HDL-cholesterol concentration was observed in the diabetic rats upon treatment with FFMTSE. These findings indicate that FFMTSE could be a potent anti-nephropathy and anti-cardiomyopathy agent in diabetic conditions.

Dyslipidemia is associated with inflammation and organ involvement in systemic lupus erythematosus

INTRODUCTION

Disturbed lipid metabolism was observed in systemic lupus erythematosus (SLE) patients. This study aimed to evaluate the relationships between dyslipidemia and visceral organ involvement, disease severity, inflammatory factors, and drug intake in SLE patients.

METHOD

Inpatients with SLE (n = 105) and healthy controls (HC) (n = 75) were recruited in this study. Clinical and laboratory data were collected from patient records. The concentrations of tumor necrosis factor receptors superfamily member1A (TNFRSF1A), member1B (TNFRSF1B) and adipokine angiopoietin-like 4 (ANGPTL4) in plasma were measured by ELISA.

RESULT

Compared to HC, serum levels of triglyceride (TG), total cholesterol (TC), low-density lipoprotein (LDL), and apolipoprotein B (ApoB) were significantly increased, while high-density lipoprotein (HDL) and apolipoprotein A1 (ApoA1) were decreased in SLE patients. Patients with higher disease activity and renal damage suffered from more severe dyslipidemia. Renal functional parameters were closely correlated with serum lipid levels. Inflammatory factors were associated with dyslipidemia. The levels of TNFRSF1A and TNFRSF1B were obviously increased and associated with kidney involvement in SLE patients. Patients with high-dose glucocorticoid intake showed more severe dyslipidemia.

CONCLUSIONS

Attention should be paid to the dyslipidemia of SLE. Dyslipidemia is associated with inflammation and organ involvement in SLE. These findings might provide a new strategy for the treatment of SLE. Key Points • Serum levels of TG, TC, LDL, and ApoB were significantly increased, while HDL and ApoA1 were decreased in SLE patients. • Patients with higher disease activity and renal damage suffered from more severe dyslipidemia. Renal functional parameters and inflammatory factors were closely correlated with serum lipid levels. • Patients with high-dose glucocorticoid intake showed more severe dyslipidemia. • These findings might provide a new strategy for the treatment of SLE.

Gemfibrozil-Induced Intracellular Triglyceride Increase in SH-SY5Y, HEK and Calu-3 Cells

Gemfibrozil is a drug that has been used for over 40 years to lower triglycerides in blood. As a ligand for peroxisome proliferative-activated receptor-alpha (PPARα), which is expressed in many tissues, it induces the transcription of numerous genes for carbohydrate and lipid-metabolism. However, nothing is known about how intracellular lipid-homeostasis and, in particular, triglycerides are affected. As triglycerides are stored in lipid-droplets, which are known to be associated with many diseases, such as Alzheimer's disease, cancer, fatty liver disease and type-2 diabetes, treatment with gemfibrozil could adversely affect these diseases. To address the question whether gemfibrozil also affects intracellular lipid-levels, SH-SY5Y, HEK and Calu-3 cells, representing three different metabolically active organs (brain, lung and kidney), were incubated with gemfibrozil and subsequently analyzed semi-quantitatively by mass-spectrometry. Importantly, all cells showed a strong increase in intracellular triglycerides (SH-SY5Y: 170.3%; HEK: 272.1%; Calu-3: 448.1%), suggesting that the decreased triglyceride-levels might be due to an enhanced cellular uptake. Besides the common intracellular triglyceride increase, a cell-line specific alteration in acylcarnitines are found, suggesting that especially in neuronal cell lines gemfibrozil increases the transport of fatty acids to mitochondria and therefore increases the turnover of fatty acids for the benefit of additional energy supply, which could be important in diseases, such as Alzheimer's disease.

Rapid identification of early renal damage in asymptomatic hyperuricemia patients based on urine Raman spectroscopy and bioinformatics analysis

Objective: The issue of when to start treatment in patients with hyperuricemia (HUA) without gout and chronic kidney disease (CKD) is both important and controversial. In this study, Raman spectroscopy (RS) was used to analyze urine samples, and key genes expressed differentially CKD were identified using bioinformatics. The biological functions and regulatory pathways of these key genes were preliminarily analyzed, and the relationship between them as well as the heterogeneity of the urine components of HUA was evaluated. This study provides new ideas for the rapid evaluation of renal function in patients with HUA and CKD, while providing an important reference for the new treatment strategy of HUA disease. Methods: A physically examined population in 2021 was recruited as the research subjects. There were 10 cases with normal blood uric acid level and 31 cases with asymptomatic HUA diagnosis. The general clinical data were collected and the urine samples were analyzed by Raman spectroscopy. An identification model was also established by using the multidimensional multivariate method of orthogonal partial least squares discriminant analysis (OPLS-DA) model for statistical analysis of the data, key genes associated with CKD were identified using the Gene Expression Omnibus (GEO) database, and key biological pathways associated with renal function damage in CKD patients with HUA were analyzed. Results: The Raman spectra showed significant differences in the levels of uric acid (640 cm^-1), urea, creatinine (1,608, 1,706 cm^-1), proteins/amino acids (642, 828, 1,556, 1,585, 1,587, 1,596, 1,603, 1,615 cm^-1), and ketone body (1,643 cm^-1) (p < 0.05). The top 10 differentially expressed genes (DEGs) associated with CKD (ALB, MYC, IL10, FOS, TOP2A, PLG, REN, FGA, CCNA2, and BUB1) were identified. Compared with the differential peak positions analyzed by the OPLS-DA model, it was found that the peak positions of glutathione, tryptophan and tyrosine may be important markers for the diagnosis and progression of CKD. Conclusion: The progression of CKD was related to the expression of the ALB, MYC, IL10, PLG, REN, and FGA genes. Patients with HUA may have abnormalities in glutathione, tryptophan, tyrosine, and energy metabolism. The application of Raman spectroscopy to analyze urine samples and interpret the heterogeneity of the internal environment of asymptomatic HUA patients can be combined with the OPLS-DA model to mine the massive clinical and biochemical examination information on HUA patients. The results can also provide a reference for identifying the right time for intervention for uric acid as well as assist the early detection of changes in the internal environment of the body. Finally, this approach provides a useful technical supplement for exploring a low-cost, rapid evaluation and improving the timeliness of screening. Precise intervention of abnormal signal levels of internal environment and energy metabolism may be a potential way to delay renal injury in patients with HUA.

Common gene signatures and molecular mechanisms of diabetic nephropathy and metabolic syndrome

Background

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease. Multiple metabolic toxicities, redox stress, and endothelial dysfunction contribute to the development of diabetic glomerulosclerosis and DN. Metabolic syndrome (MetS) is a pathological state in which the body's ability to process carbohydrates, fats, and proteins is compromised because of metabolic disorders, resulting in redox stress and renal remodeling. However, a causal relationship between MetS and DN has not been proven. This study aimed to provide valuable information for the clinical diagnosis and treatment of MetS with DN.

Methods

Here, transcriptome data of DN and MetS patients were obtained from the Gene Expression Omnibus database, and seven potential biomarkers were screened using bioinformatics analysis. In addition, the relationship between these marker genes and metabolism and immune infiltration was explored. Among the identified marker genes, the relationship between PLEKHA1 and the cellular process, oxidative phosphorylation (OXPHOS), in DN was further investigated through single-cell analysis.

Results

We found that PLEKHA1 may represent an important biomarker that perhaps initiates DN by activating B cells, proximal tubular cells, distal tubular cells, macrophages, and endothelial cells, thereby inducing OXPHOS in renal monocytes.

Conclusion

Overall, our findings can aid in further investigation of the effects of drug treatment on single cells of patients with diabetes to validate PLEKHA1 as a therapeutic target and to inform the development of targeted therapies.

Role of miR-379 in high-fat diet-induced kidney injury and dysfunction

Obesity is associated with increased risk for diabetes and damage to the kidneys. Evidence suggests that miR-379 plays a role in the pathogenesis of diabetic kidney disease. However, its involvement in obesity-induced kidney injury is not known and was therefore investigated in this study by comparing renal phenotypes of high-fat diet (HFD)-fed wild-type (WT) and miR-379 knockout (KO) mice. Male and female WT mice on the HFD for 10 or 24 wk developed obesity, hyperinsulinemia, and kidney dysfunction manifested by albuminuria and glomerular injuries. However, these adverse alterations in HFD-fed WT mice were significantly ameliorated in HFD-fed miR-379 KO mice. HFD feeding increased glomerular expression of miR-379 and decreased its target gene, endoplasmic reticulum (ER) degradation enhancing α-mannosidase-like protein 3 (Edem3), a negative regulator of ER stress. Relative to the standard chow diet-fed controls, expression of profibrotic transforming growth factor-β1 (Tgf-β1) was significantly increased, whereas Zeb2, which encodes ZEB2, a negative regulator of Tgf-β1, was decreased in the glomeruli in HFD-fed WT mice. Notably, these changes as well as HFD-induced increased expression of other profibrotic genes, glomerular hypertrophy, and interstitial fibrosis in HFD-fed WT mice were attenuated in HFD-fed miR-379 KO mice. In cultured primary glomerular mouse mesangial cells (MMCs) isolated from WT mice, treatment with high insulin (mimicking hyperinsulinemia) increased miR-379 expression and decreased its target, Edem3. Moreover, insulin also upregulated Tgf-β1 and downregulated Zeb2 in WT MMCs, but these changes were significantly attenuated in MMCs from miR-379 KO mice. Together, these experiments revealed that miR-379 deletion protects mice from HFD- and hyperinsulinemia-induced kidney injury at least in part through reduced ER stress.NEW & NOTEWORTHY miR-379 knockout mice are protected from high-fat diet (HFD)-induced kidney damage through key miR-379 targets associated with ER stress (Edem3). Mechanistically, treatment of mesangial cells with insulin (mimicking hyperinsulinemia) increased expression of miR-379, Tgf-β1, miR-200, and Chop and decreases Edem3. Furthermore, TGF-β1-induced fibrotic genes are attenuated by a GapmeR targeting miR-379. The results implicate a miR-379/EDEM3/ER stress/miR-200c/Zeb2 signaling pathway in HFD/obesity/insulin resistance-induced renal dysfunction. Targeting miR-379 with GapmeRs can aid in the treatment of obesity-induced kidney disease.

Implications of cancer stem cells in diabetes and pancreatic cancer

This review provides a detailed study of pancreatic cancer (PC) and the implication of different types of cancers concerning diabetes. The combination of anti-diabetic drugs with other anti-cancer drugs and phytochemicals can help prevent and treat this disease. PC cancer stem cells (CSCs) and how they migrate and develop into malignant tumors are discussed. A detailed explanation of the different mechanisms of diabetes development, which can enhance the pancreatic CSCs' proliferation by increasing the IGF factor levels, epigenetic modifications, DNA damage, and the influence of lifestyle factors like obesity, and inflammation, has been discussed. It also explains how cancer due to diabetes is associated with high mortality rates. One of the well-known diabetic drugs, metformin, can be combined with other anti-cancer drugs and prevent the development of PC and has been taken as one of the prime focus in this review. Overall, this paper provides insight into the relationship between diabetes and PC and the methods that can be employed to diagnose this disease at an earlier stage successfully.

Paraoxonase 1 Ameliorates Renal Lipotoxicity by Activating Lipophagy and Inhibiting Pyroptosis

Several studies in recent years have shown that lipid overload causes lipotoxic damage to the kidney, and oxidative stress, inflammation, and autophagic arrest are all important mechanisms of renal lipotoxicity. However, effective measures with therapeutic effects on renal lipotoxicity are limited. The present study indicated the protective effect of the paraoxonase 1 (PON1) against renal lipotoxicity in high-fat diet-fed scavenger receptor class B type I-deficient (SR-BI-/-) mice. The results showed that SR-BI-/- mice exhibited significant renal pathologic characteristics, such as oxidative stress, inflammation, and fibrosis, under a normal chow diet, and were accompanied by dyslipidemia and reduced plasma PON1 activity and renal PON1 levels. PON1 overexpression significantly attenuated the above pathologic changes in the kidneys of SR-BI-/- mice fed with a high-fat diet. Mechanistically, PON1 may ameliorate renal oxidative stress by reducing reactive oxygen species production, reduce renal lipid accumulation by inhibiting AKT/mechanistic target of rapamycin kinase pathway to activate lipophagy, and reduce the occurrence of inflammation and cell death by inhibiting Nod-like receptor family protein 3 inflammasome-mediated pyroptosis. The present study is the first to show that PON1 overexpression can effectively alleviate renal lipotoxicity injury, and PON1 may be a promising therapeutic strategy for the treatment of renal lipotoxicity-related diseases.

Hypercaloric Diet Promotes Metabolic Disorders and Impaired Kidney Function

Poor dietary habits such as overconsumption of hypercaloric diets characterized by a high content of fructose and fat are related to metabolic abnormalities development such as obesity, diabetes, and dyslipidemia. Accumulating evidence supports the hypothesis that if energy intake gradually exceeds the body's ability to store fat in adipose tissue, the prolonged metabolic imbalance of circulating lipids from endogenous and exogenous sources leads to ectopic fat distribution in the peripheral organs, especially in the heart, liver, and kidney. The kidney is easily affected by dyslipidemia, which induces lipid accumulation and reflects an imbalance between fatty acid supply and fatty acid utilization. This derives from tissue lipotoxicity, oxidative stress, fibrosis, and inflammation, resulting in structural and functional changes that lead to glomerular and tubule-interstitial damage. Some authors indicate that a lipid-lowering pharmacological approach combined with a substantial lifestyle change should be considered to treat chronic kidney disease (CKD). Also, the new therapeutic target identification and the development of new drugs targeting metabolic pathways involved with kidney lipotoxicity could constitute an additional alternative to combat the complex mechanisms involved in impaired kidney function. In this review article, we first provide the pathophysiological evidence regarding the impact of hypercaloric diets, such as high-fat diets and high-fructose diets, on the development of metabolic disorders associated with impaired renal function and the molecular mechanisms underlying tissue lipid deposition. In addition, we present the current progress regarding translational strategies to prevent and/or treat kidney injury related to the consumption of hypercaloric diets.

Metabolic reprogramming: A novel therapeutic target in diabetic kidney disease

Diabetic kidney disease (DKD) is one of the most common microvascular complications of diabetes mellitus. However, the pathological mechanisms contributing to DKD are multifactorial and poorly understood. Diabetes is characterized by metabolic disorders that can bring about a series of changes in energy metabolism. As the most energy-consuming organs secondary only to the heart, the kidneys must maintain energy homeostasis. Aberrations in energy metabolism can lead to cellular dysfunction or even death. Metabolic reprogramming, a shift from mitochondrial oxidative phosphorylation to glycolysis and its side branches, is thought to play a critical role in the development and progression of DKD. This review focuses on the current knowledge about metabolic reprogramming and the role it plays in DKD development. The underlying etiologies, pathological damages in the involved cells, and potential molecular regulators of metabolic alterations are also discussed. Understanding the role of metabolic reprogramming in DKD may provide novel therapeutic approaches to delay its progression to end-stage renal disease.

Adropin Carried by Reactive Oxygen Species-Responsive Nanocapsules Ameliorates Renal Lipid Toxicity in Diabetic Mice

Diabetic kidney disease (DKD) is a common diabetes complication mainly caused by lipid toxicity characterized by oxidative stress. Studies have shown that adropin (Ad) regulates energy metabolism and may be an effective target to improve DKD. This study investigated the effect of exogenous Ad encapsulated in reactive oxygen species (ROS)-responsive nanocapsules (Ad@Gel) on DKD. HK2 cells were induced with high glucose (HG) and intervened with Ad@Gel. A diabetes mouse model was established using HG and high-fat diet combined with streptozotocin and treated with Ad@Gel to observe its effects on renal function, pathological damage, lipid metabolism, and oxidative stress. Results showed that Ad@Gel could protect HK2 from HG stimulation in vitro. It also effectively controls blood glucose and lipid levels, improves renal function, inhibits excessive production of ROS, protects mitochondria from damage, improves lipid deposition in renal tissues, and downregulates the expression of lipogenic proteins SEBP-1 and ADRP in DKD mice. In HG-induced HK2 cells or the kidney of DKD patients, the low expression of neuronatin (Nnat) and high expression of translocator protein (TSPO) were observed. Knockdown Nnat or overexpression of TSPO significantly reversed the effect of Ad@Gel on improving mitochondrial damage. In addition, knockdown Nnat also significantly reversed the effect of Ad@Gel on lipid metabolism. The results suggest that the effect of Ad on DKD may be achieved by activating Nnat to improve lipid metabolism and inhibit TSPO activity, thereby enhancing mitochondrial function.

Moderate intensity of static magnetic fields can alter the avoidance behavior and fat storage of Caenorhabditis elegans via serotonin

Man-made static magnetic fields (SMFs) widely exist in human life as a physical environmental factor. However, the biological responses to moderate SMFs exposure and their underlying mechanisms are largely unknown. The present study was focused on exploring the nervous responses to moderate-intensity SMFs at 0.5 T and 1 T in Caenorhabditis elegans (C. elegans). We found that SMFs at either 0.5 T or 1 T had no statistically significant effects on the locomotor behaviors, while the 1 T magnetic field increased pharyngeal pumping. The avoidance behavior of the pathogenic Pseudomonas aeruginosa was greatly decreased in either 0.5 T or 1 T SMFs exposed nematodes, and the learning index was reducede from 0.52 ± 0.11 to 0.23 ± 0.17 and 0.16 ± 0.11, respectively. The total serotonin level was increased by 17.08% and 16.45% with the treatment of 0.5 T and 1 T SMF, compared to the control group; however, there were minimal effects of SMFs on other three neurotransmitters including choline, γ-aminobutyric acid (GABA), dopamine. RT-qPCR was used to further investigate the expression of serotonin-related genes, including rate-limiting enzymes, transcription factors and transport receptors. The expression levels of tph-1 and unc-86 genes were increased by SMF exposure, while those of ocr-2, osm-9, ser-1 and mod-1 genes were decreased. With the staining of lipid in either wild-type N2 or tph-1 mutants, we found that 0.5 T and 1 T SMFs decreased fat storage in C. elegans via serotonin pathway. Our study demonstrated that moderate-intensity SMFs induced neurobehavioral disorder and the reduction of fat storage by disturbing the secretion of serotonin in C. elegans, which provided new insights into elucidating nervous responses of C. elegans to moderate-intensity SMFs.

Flazin as a Lipid Droplet Regulator against Lipid Disorders

Lipid disorders are closely related to numerous metabolic diseases, and lipid droplets (LDs) have been considered as a new target for regulating lipid metabolism. Dietary intervention and nutraceuticals provide safe and long-term beneficial effects for treating metabolic diseases. Flazin is a diet-derived bioactive constituent mainly existing in fermented foods, of which the lipid metabolism improvement function has not been studied. In this study, the effect of flazin on lipid regulation at both cell level and organelle level was investigated. Lipidomic profiling showed that flazin significantly decreased cellular triglyceride (TG) by 12.0–22.4% compared with modeling groups and improved the TG and free fatty acid profile. LD staining revealed that flazin efficiently reduced both cellular neutral lipid content by 17.4–53.9% and LD size by 10.0–35.3%. Furthermore, nanoelectrospray ionization mass spectrometry analysis proved that flazin exhibited a preferential suppression of LD TG and regulated LD morphology, including a size decrease and surface property improvement. An evaluation of related gene expression suggested the mechanism to be lipolysis promotion and lipogenesis inhibition. These findings indicated that flazin might be an LD regulator for reversing lipid metabolism disturbance. Moreover, the strategy proposed in this study may contribute to developing other nutraceuticals for treating lipid disorder-related metabolic diseases.

Lipidomic Analysis Reveals the Protection Mechanism of GLP-1 Analogue Dulaglutide on High-Fat Diet-Induced Chronic Kidney Disease in Mice

Many clinical studies have suggested that glucagon-like peptide-1 receptor agonists (GLP-1RAs) have renoprotective properties by ameliorating albuminuria and increasing glomerular filtration rate in patients with type 2 diabetes mellitus (T2DM) and chronic kidney disease (CKD) by lowering ectopic lipid accumulation in the kidney. However, the mechanism of GLP-1RAs was hitherto unknown. Here, we conducted an unbiased lipidomic analysis using ultra-high-performance liquid chromatography/electrospray ionization-quadrupole time-of-flight mass spectrometry (UHPLC/ESI-Q-TOF-MS) and matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to reveal the changes of lipid composition and distribution in the kidneys of high-fat diet-fed mice after treatment with a long-acting GLP-1RA dulaglutide for 4 weeks. Treatment of dulaglutide dramatically improved hyperglycemia and albuminuria, but there was no substantial improvement in dyslipidemia and ectopic lipid accumulation in the kidney as compared with controls. Intriguingly, treatment of dulaglutide increases the level of an essential phospholipid constituent of inner mitochondrial membrane cardiolipin at the cortex region of the kidneys by inducing the expression of key cardiolipin biosynthesis enzymes. Previous studies demonstrated that lowered renal cardiolipin level impairs kidney function via mitochondrial damage. Our untargeted lipidomic analysis presents evidence for a new mechanism of how GLP-1RAs stimulate mitochondrial bioenergetics via increasing cardiolipin level and provides new insights into the therapeutic potential of GLP-1RAs in mitochondrial-related diseases.

The Roles of Blood Lipid-Metabolism Genes in Immune Infiltration Could Promote the Development of IDD

Objectives: Intervertebral disc degeneration is a progressive and chronic disease, usually manifesting as low back pain. This study aimed to screen effective biomarkers for medical practice as well as figuring out immune infiltration situations between circulation and intervertebral discs.

Methods: Gene expression profiles of GSE124272 was included for differentially analysis, WGCNA and immune infiltration analysis from GEO database, and other GSE series were used as validation datasets. A series of validation methods were conducted to verify the robustness of hub genes, such as principal component analysis, machine learning models, and expression verification. Lastly, nomogram was established for medical practice.

Results: 10 genes were commonly screened via combination of DEGs, WGCNA analysis and lipid metabolism related genes. Furthermore, 3 hub gens CYP27A1, FAR2, CYP1B1 were chosen for subsequent analysis based on validation of different methods. GSEA analysis discovered that neutrophil extracellular traps formation and NOD-like receptor signaling pathway was activated during IDD. Immune infiltration analysis demonstrated that the imbalance of neutrophils and γδT cells were significantly correlated with IDD progression. Nomogram was established based on CYP27A1, FAR2, CYP1B1 and age, the calibration plot confirmed the stability of our model.

Conclusion: CYP27A1, FAR2, CYP1B1 were considered as hub lipid metabolism related genes (LMRGs) in the development of IDD, which were regarded as candidate diagnostic biomarkers especially in circulation. The effects are worth expected in the early diagnosis of IDD through detecting these genes in blood.

Cysteine as a Multifaceted Player in Kidney, the Cysteine-Related Thiolome and Its Implications for Precision Medicine

In this review encouraged by original data, we first provided in vivo evidence that the kidney, comparative to the liver or brain, is an organ particularly rich in cysteine. In the kidney, the total availability of cysteine was higher in cortex tissue than in the medulla and distributed in free reduced, free oxidized and protein-bound fractions (in descending order). Next, we provided a comprehensive integrated review on the evidence that supports the reliance on cysteine of the kidney beyond cysteine antioxidant properties, highlighting the relevance of cysteine and its renal metabolism in the control of cysteine excess in the body as a pivotal source of metabolites to kidney biomass and bioenergetics and a promoter of adaptive responses to stressors. This view might translate into novel perspectives on the mechanisms of kidney function and blood pressure regulation and on clinical implications of the cysteine-related thiolome as a tool in precision medicine.

Cellular crosstalk of glomerular endothelial cells and podocytes in diabetic kidney disease

Diabetic kidney disease (DKD) is a serious microvascular complication of diabetes and is the leading cause of end-stage renal disease (ESRD). Persistent proteinuria is an important feature of DKD, which is caused by the destruction of the glomerular filtration barrier (GFB). Glomerular endothelial cells (GECs) and podocytes are important components of the GFB, and their damage can be observed in the early stages of DKD. Recently, studies have found that crosstalk between cells directly affects DKD progression, which has prospective research significance. However, the pathways involved are complex and largely unexplored. Here, we review the literature on cellular crosstalk of GECs and podocytes in the context of DKD, and highlight specific gaps in the field to propose future research directions. Elucidating the intricates of such complex processes will help to further understand the pathogenesis of DKD and develop better prevention and treatment options.

Tubular epithelial cell-to-macrophage communication forms a negative feedback loop via extracellular vesicle transfer to promote renal inflammation and apoptosis in diabetic nephropathy

Background: Macrophage infiltration around lipotoxic tubular epithelial cells (TECs) is a hallmark of diabetic nephropathy (DN). However, how these two types of cells communicate remains obscure. We previously demonstrated that LRG1 was elevated in the process of kidney injury. Here, we demonstrated that macrophage-derived, LRG1-enriched extracellular vesicles (EVs) exacerbated DN.

Methods: We induced an experimental T2DM mouse model with a HFD diet for four months. Renal primary epithelial cells and macrophage-derived EVs were isolated from T2D mice by differential ultracentrifugation. To investigate whether lipotoxic TEC-derived EV (EV_e) activate macrophages, mouse bone marrow-derived macrophages (BMDMs) were incubated with EV_e. To investigate whether activated macrophage-derived EVs (EV_m) induce lipotoxic TEC apoptosis, EV_m were cocultured with primary renal tubular epithelial cells. Subsequently, we evaluated the effect of LRG1 in EV_e by investigating the apoptosis mechanism.

Results: We demonstrated that incubation of primary TECs of DN or HK-2 mTECs with lysophosphatidyl choline (LPC) increased the release of EV_e. Interestingly, TEC-derived EV_e activated an inflammatory phenotype in macrophages and induced the release of macrophage-derived EV_m. Furthermore, EV_m could induce apoptosis in TECs injured by LPC. Importantly, we found that leucine-rich α-2-glycoprotein 1 (LRG1)-enriched EV_e activated macrophages via a TGFβR1-dependent process and that tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-enriched EV_m induced apoptosis in injured TECs via a death receptor 5 (DR5)-dependent process.

Conclusion: Our findings indicated a novel cell communication mechanism between tubular epithelial cells and macrophages in DN, which could be a potential therapeutic target.

Renal fat fraction is significantly associated with the risk of chronic kidney disease in patients with type 2 diabetes

BACKGROUNDS

Ectopic fat deposition is closely related to chronic kidney disease (CKD). Currently, there are few population studies that have been conducted to determine the relationship between renal parenchyma fat deposition and the risk of CKD among patients with type 2 diabetes mellitus (T2DM). Therefore, we employed magnetic resonance imaging (MRI) to detect renal parenchyma fat content in individuals with T2DM, expressed as renal fat fraction (FF), to explore whether renal FF is an important risk factor for CKD in patients with T2DM.

METHODS

In this cross-sectional study, 189 subjects with T2DM were enrolled. CKD was defined as the estimated glomerular filtration rate (eGFR)<60 mL/min/1.73m². Measurement of the renal FF was performed on a 3.0-T MRI (MAGNETOM Skyra, Siemens, Erlangen, Germany). Binary logistic regression was used to determine the association between tertiles of renal FF and risk of CKD. Receiver-operator characteristic (ROC) curves were constructed to evaluate the sensitivity and specificity of renal FF in detecting CKD in T2DM patients.

RESULTS

The patients were divided into three groups according to tertiles of the renal FF level (2.498 - 7.434). As renal FF increases, patients tend to be older, and more abdominally obese, with a decreased eGFR (p<0.05). After adjustment for potential confounders, patients in the highest tertile of renal FF had a significantly increased risk of CKD than those in the lowest tertile (odds ratio (OR) = 3.98, 95% confidence interval (CI) = 1.12 - 14.09, p = 0.032), and the area under the ROC curve for this model was 0.836 (0.765-0.907).

CONCLUSIONS

The renal FF is significantly independently associated with CKD in patients with T2DM.

Predictive Value of Plasma Atherogenic Index for Microalbuminuria in Newly Diagnosed Patients with Type 2 Diabetes Mellitus

PURPOSE

This study aims to explore the predictive value of plasma atherogenic index of plasma (AIP) for microalbuminuria (MAU) in newly diagnosed patients with type 2 diabetes mellitus (T2DM).

METHODS

This study was a retrospective study, which included 335 newly diagnosed T2DM patients. They were divided into microalbuminuria group (group A, n = 105 cases) and no microalbuminuria group (group B, n = 230 cases) according to whether microalbuminuria occurred. General information and laboratory examination indexes of patients were collected, and AIP was calculated. Multivariate logistic regression analysis was used to analyze the independent risk factors of microalbuminuria in T2DM patients, and receiver operating characteristic curve (ROC) was established to evaluate the predictive value of AIP on MAU of newly diagnosed T2DM patients.

RESULTS

According to general data analysis, AIP level in group A was significantly higher than that in group B (P < 0.05). Multivariate logistic regression analysis showed that AIP was an independent risk factor for microalbuminuria (P < 0.05). The receiver operating characteristic curve showed that the area under the curve (AUC) of AIP was 0.772 (P < 0.05), which had a good predictive value for the occurrence of MAU in newly diagnosed T2DM patients. The waist-hip ratio, triglyceride, high-density lipoprotein cholesterol, fasting blood glucose, glycosylated hemoglobin and AIP were used to make a joint model, and the AUC was 0.841 (P < 0.05), which had a better predictive value for the occurrence of MAU.

CONCLUSIONS

AIP is an independent risk factor and could predict the occurrence of MAU in newly diagnosed T2DM patients. AIP provides clinicians a reliable basis to quickly identify high-risk patients and formulate appropriate treatment strategies.

Comparisons of the Relationships Between Multiple Lipid Indices and Diabetic Kidney Disease in Patients With Type 2 Diabetes: A Cross-Sectional Study

BACKGROUND

Dyslipidemia is a well-recognized risk factor for diabetic kidney disease (DKD) in patients with type 2 diabetes (T2D). Growing evidences have shown that compared with the traditional lipid parameters, some lipid ratios may provide additional information of lipid metabolism. Thus, the present study aimed to investigate which lipid index was most related to DKD.

METHODS

This study was a cross-sectional study that enrolled patients with T2D from January 2021 to October 2021. Each participant was screened for DKD, and the diagnostic criterion for DKD is estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m² or urinary albumin-to-creatinine ratio (UACR) ≥ 30 mg/g for 3 months. Fasting blood was collected to determine lipid profiles by an automatic biochemical analyzer, and lipid ratios were calculated based on corresponding lipid parameters. Spearman's correlation analyses were conducted to assess the correlations between lipid indices and kidney injury indices, and binary logistic regression analyses were conducted to explore the relationship between lipid indices and the risk of DKD.

RESULTS

A total of 936 patients with T2D were enrolled in the study, 144 (15.38%) of whom had DKD. The LDL-C/Apo B ratios were positively correlated with eGFR (r = 0.146, p < 0.05) and inversely correlated to cystatin C and UACR (r = -0.237 and -0.120, both p < 0.001). Multiple logistic regression demonstrated that even after adjusting for other clinical covariates, the LDL-C/Apo B ratios were negatively related to DKD, and the odds ratio (95% confidence interval) was 0.481 (0.275-0.843). Furthermore, subgroup analyses revealed that compared with patients with normal lipid profiles and a high LDL-C/Apo B ratio, the odds ratio of DKD in patients with normal lipid metabolism and a low LDL-C/Apo B ratio was 2.205 (1.136-4.280) after adjusting for other clinical covariates.

CONCLUSION

In patients with T2D, the LDL-c/Apo B ratio was most closely associated with DKD among various lipid indices, and a lower LDL-C/Apo B ratio was associated with increased risks of DKD among patients with T2D.

Acylcarnitines: Can They Be Biomarkers of Diabetic Nephropathy?

Diabetic nephropathy (DN), one of the most serious microvascular complications of diabetes mellitus (DM), may progress to end-stage renal disease (ESRD). Current biochemical biomarkers, such as urinary albumin excretion rate (UAER), have limitations for early screening and monitoring of DN. Recent studies have identified some metabolites as candidate biomarkers for early detection of DN. In this review, we summarize the role of dysregulated acylcarnitines (AcylCNs) in DN pathophysiology. Lower abundance of short- and medium-chain AcylCNs and higher long-chain AcylCNs often occurred in DM with normal albuminuria and microalbuminuria, compared with advanced stages of DN. The increase of long-chain AcylCNs was supposed to be an adaptive compensation in fat acids (FAs) oxidation in the early stage of DN. Conversely, the decrease of long-chain AcylCNs was due to incomplete oxidation of FAs in advanced stage of DN. Thus, AcylCNs may serve as sensitive biomarkers in predicting the risk of DN.