Role of oxidized low density lipoproteins and free fatty acids in the pathogenesis of glomerulopathy and tubulointerstitial lesions in type 2 diabetes

Inhibition of Aberrant Activated Fibroblast-Like Synoviocytes in Rheumatoid Arthritis by Leishmania Peptide via the Regulation of Fatty Acid Synthesis Metabolism

The Leishmania homolog of receptors for activated C kinase (LACK) protein is derived from Leishmania parasites L. major. The polypeptide LACK156-173 has been shown to confer protection against murine autoimmune arthritis. Fibroblast-like synoviocytes (FLSs) play a pivotal role in the synovial invasion and joint destruction observed in rheumatoid arthritis (RA). The study reveals that LACK156-173 can inhibit the aggressive phenotype of RA-FLSs by restoring dysregulated fatty acid synthesis metabolism. In RA-FLSs, overexpression of fatty acid synthase (FASN) leads to excessive fatty acid accumulation, which in turn promotes mitochondrial fragmentation by enhancing phosphorylation at the ser616 site of dynamin 1-like protein (DRP1). This process increases reactive oxygen species (ROS) production and activates the PI3K/mTOR/NF-κB pathway, thereby facilitating the transition of RA-FLSs to an aggressive inflammatory and bone-damaging phenotype. LACK156-173 is internalized into the cytoplasm via CAPN2-mediated endocytosis, where it directly binds to FASN and inhibits its activity. The findings suggest that targeting the restoration of fatty acid metabolism could potentially alleviate synovial invasion and joint damage in RA. LACK156-173 may therefore hold therapeutic promise for RA patients.

Association between triglyceride to high-density lipoprotein cholesterol ratio and microalbuminuria in the Chinese population

The evidence for the association between the triglyceride (TG) to high-density lipoprotein cholesterol (HDL-c) ratio and the risk of developing microalbuminuria is still limited in the Chinese population. Therefore, our research will endeavor to explore the relationship between the two. The cross-sectional survey enrolled 32,877 general population from eight regional centers in China. If the urinary albumin-creatinine ratio (UACR) ≥ 30 mg/g, it was considered microalbuminuria. The dependent variable in the study was microalbuminuria, while the independent variable was the TG/HDL-c ratio. A binary logistic regression model was utilized to examine the independent association between the likelihood of microalbuminuria and the TG/HDL-c ratio. A generalized additive model (GAM) and spline smoothing were employed to investigate non-linear relationships between these two variables. To confirm the findings and pinpoint important turning points, subgroup and threshold effect tests were performed. The average age of the study participants was 57.67 ± 9.29 years, with 22,052 (67%) females and 10,825 (33%) males. The ratio of TG/HDL-c had a median value of 1.06, while the UACR had a median value of 9.92 mg/g. The prevalence of microalbuminuria was 14.4%. Following covariate adjustment, the prevalence of microalbuminuria and the TG/HDL-c ratio showed a significant positive connection (OR = 1.17,95% CI 1.13-1.21). Interestingly, we discovered a non-linear relationship between the occurrence of microalbuminuria and the TG/HDL-c ratio. At a TG/HDL-c ratio of 0.911, we detected an inflection point, with ORs of 1.12 (95% CI: 1.08, 1.17) on the right side of the point and 1.89 (95% CI: 1.51, 2.36) on the left. Subgroup analyses further validated the results. Our research revealed a positive and non-linear connection between the TG/HDL-c ratio and the prevalence of microalbumin in Chinese individuals. The connection was especially robust when the TG/HDL-c ratio was below 0.911. Reducing TG or raising HDL-c levels in order to lower the TG/HDL-c ratio may significantly mitigate the risk of microalbuminuria.

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.

Glucagon receptor activation contributes to the development of kidney injury

The underlying causes of diabetic kidney disease are still largely unknown. New insights into the contributing causes of diabetic nephropathy are important to prevent this complication. Hyperglycemia and hypertension are some of the risk factors for diabetic nephropathy. However, the incidence of diabetic nephropathy is increasing despite efforts to normalize blood glucose levels and blood pressure. Therefore, other factors should be investigated as causes of diabetic nephropathy. We investigated whether long-term increased plasma levels of glucagon contribute to the development of pathophysiological changes in kidney function as seen in patients with diabetic nephropathy. Using mouse models of chronic activation and inactivation of glucagon receptor signaling, we investigated whether glucagon is involved in changes in renal function, renal structure, and transcriptional changes. We found several histopathological changes in the kidney, such as thickening of the parietal layer of Bowman's capsule, glomerular mesangial cell expansion, and significant albuminuria in the mice with activated glucagon receptor signaling. Opposite effects on mesangial area expansion and the development of albuminuria were demonstrated in mice with glucagon receptor inactivation. RNA sequencing data revealed that transcription of genes related to fatty acid metabolism, podocytes, Na+-K+-ATPase, and sodium/glucose transport was significantly changed in mice with activated glucagon receptor signaling. These data implicate that glucagon receptor signaling is involved in the development of kidney injury, as seen in type 2 diabetes, and that glucagon receptor is a potential therapeutic target in the treatment of diabetes. NEW & NOTEWORTHY This study suggests that the glucagon receptor is a potential therapeutic target in the treatment of diabetic kidney disease. We show, in mice, that long-term treatment with a glucagon analog showed not only pathophysiological changes and changes in renal function but also transcriptional changes in the kidneys, whereas opposite effects were demonstrated in mice with glucagon receptor inactivation. Therefore, the use of glucagon in a treatment regimen requires investigation of possible metabolic and renal abnormalities.

Association between non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) and diabetic kidney disease in patients with diabetes in the United States: a cross-sectional study

BACKGROUND

This paper investigated the link between non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) and diabetic kidney disease (DKD) in adult diabetic patients and identified the optimal NHHR value for impacting DKD.

METHODS

This cross-sectional research made use of records from the National Health and Nutrition Examination Survey (NHANES) executed between 2005 and 2016. The link of NHHR to DKD risk was analyzed by logistic regression and restricted cubic spline (RCS) models. The stability and reliability of the results were assessed by subgroup analysis and sensitivity analysis.

RESULTS

In total, 4,177 participants were involved. As a continuous variable, NHHR was markedly connected to an increased risk of DKD (OR 1.07, 95% CI 1.02, 1.12, P < 0.01). When NHHR was grouped in quartiles, relative to the reference set, the highest NHHR group was also linked to a heightened risk of DKD (OR 1.23, 95% CI 1.01, 1.50, P < 0.05). The outcome of RCS show a "J" shaped correlation between NHHR and DKD risk (P for nonlinear = 0.0136). The risk of developing DKD was the lowest when NHHR equals 2.66. Subgroup analysis revealed that the link of NHHR to DKD persisted in participants aged below 40, females, non-smokers, and those without hyperuricemia. Sensitivity analysis demonstrated a certain robustness in this association.

CONCLUSION

A meaningful link is present between NHHR and DKD. An NHHR value of around 2.66 could represent the ideal cutoff for assessing DKD risk.

Morroniside attenuates podocytes lipid deposition in diabetic nephropathy: A network pharmacology, molecular docking and experimental validation study

BACKGROUND

Dysregulation of lipid metabolism is a key factor influencing the progression of diabetic nephropathy (DN). Morroniside (MOR) is a major active compound isolated from the traditional Chinese herb Cornus officinalis, our previous research found that it can improve the lipid deposition of renal tubular epithelial cells. The purpose of this study is to explore whether MOR can improve podocyte lipid deposition and its mechanism of reducing DN.

METHODS

Initially, we used network pharmacology and bioinformatics techniques to predict the relationship between renal lipid metabolism of MOR and DN. Subsequently, the binding activity of MOR with lipid-related proteins was studied by molecular docking to determine how MOR acts through these proteins. After determining the target of MOR, animal experiments and cell tests were carried out to verify it.

RESULTS

Using network pharmacology, bioinformatics, and molecular docking, target proteins for MOR treatment of DN were predicted and screened, including PGC-1α, LXRs, ABCA1, PPARY, CD36, and nephrin. It is particularly noted that MOR effectively binds to PGC-1α, while LXRs, ABCA1, PPARY and CD36 are downstream molecules of PGC-1α. Silencing the PGC-1α gene significantly reduced the therapeutic effects of MOR. Conversely, in groups without PGC-1α knockdown, MOR was able to increase the expression levels of PGC-1α and influence the expression of downstream proteins. Furthermore, through in vivo and in vitro experiments, utilizing techniques such as lipid droplet staining, PAS, MASSON staining, immunofluorescence, and Western blot, we found that MOR effectively elevated the expression levels of the podocyte protein nephrin and lipid metabolism-regulating proteins PGC-1α, PPARY, and ABCA1, while significantly inhibiting the expression of the lipid accumulation promoter CD36.

CONCLUSION

MOR can regulate the cholesterol efflux in podocytes via the PGC-1α/LXRs/ABCA1 signaling pathway, and control cholesterol intake via the PGC-1α/PPARY/CD36 signaling pathway, thereby ameliorating lipid deposition in DN.

Clinical characteristics and treatment compounds of obesity-related kidney injury

Disorders in energy homeostasis can lead to various metabolic diseases, particularly obesity. The obesity epidemic has led to an increased incidence of obesity-related nephropathy (ORN), a distinct entity characterized by proteinuria, glomerulomegaly, progressive glomerulosclerosis, and renal function decline. Obesity and its associated renal damage are common in clinical practice, and their incidence is increasing and attracting great attention. There is a great need to identify safe and effective therapeutic modalities, and therapeutics using chemical compounds and natural products are receiving increasing attention. However, the summary is lacking about the specific effects and mechanisms of action of compounds in the treatment of ORN. In this review, we summarize the important clinical features and compound treatment strategies for obesity and obesity-induced kidney injury. We also summarize the pathologic and clinical features of ORN as well as its pathogenesis and potential therapeutics targeting renal inflammation, oxidative stress, insulin resistance, fibrosis, kidney lipid accumulation, and dysregulated autophagy. In addition, detailed information on natural and synthetic compounds used for the treatment of obesity-related kidney disease is summarized. The synthesis of detailed information aims to contribute to a deeper understanding of the clinical treatment modalities for obesity-related kidney diseases, fostering the anticipation of novel insights in this domain.

Lipid metabolism disorder in diabetic kidney disease

Diabetic kidney disease (DKD), a significant complication associated with diabetes mellitus, presents limited treatment options. The progression of DKD is marked by substantial lipid disturbances, including alterations in triglycerides, cholesterol, sphingolipids, phospholipids, lipid droplets, and bile acids (BAs). Altered lipid metabolism serves as a crucial pathogenic mechanism in DKD, potentially intertwined with cellular ferroptosis, lipophagy, lipid metabolism reprogramming, and immune modulation of gut microbiota (thus impacting the liver-kidney axis). The elucidation of these mechanisms opens new potential therapeutic pathways for DKD management. This research explores the link between lipid metabolism disruptions and DKD onset.

Chronic kidney disease in a murine model of non-alcoholic steatohepatitis (NASH)

Clinical studies suggest that non-alcoholic steatohepatitis (NASH) is an independent risk factor for chronic kidney disease (CKD), but causality and mechanisms linking these two major diseases are lacking. To assess whether NASH can induce CKD, we have characterized kidney function, histological features, transcriptomic and lipidomic profiles in a well-validated murine NASH model. Mice with NASH progressively developed significant podocyte foot process effacement, proteinuria, glomerulosclerosis, tubular epithelial cell injury, lipid accumulation, and interstitial fibrosis. The progression of kidney fibrosis paralleled the severity of the histologic NASH-activity score. Significantly, we confirmed the causal link between NASH and CKD by orthotopic liver transplantation, which attenuated proteinuria, kidney dysfunction, and fibrosis compared with control sham operated mice. Transcriptomic analysis of mouse kidney cortices revealed differentially expressed genes that were highly enriched in mitochondrial dysfunction, lipid metabolic process, and insulin signaling pathways in NASH-induced CKD. Lipidomic analysis of kidney cortices further revealed that phospholipids and sphingolipids were the most significantly changed lipid species. Notably, we found similar kidney histological changes in human NASH and CKD. Thus, our results confirm a causative role of NASH in the development of CKD, reveal potential pathophysiologic mechanisms of NASH-induced kidney injury, and established a valuable model to study the pathogenesis of NASH-associated CKD. This is an important feature of fatty liver disease that has been largely overlooked but has clinical and prognostic importance.

Gut microbial metabolites SCFAs and chronic kidney disease

The global incidence of Chronic Kidney Disease (CKD) is steadily escalating, with discernible linkage to the intricate terrain of intestinal microecology. The intestinal microbiota orchestrates a dynamic equilibrium in the organism, metabolizing dietary-derived compounds, a process which profoundly impacts human health. Among these compounds, short-chain fatty acids (SCFAs), which result from microbial metabolic processes, play a versatile role in influencing host energy homeostasis, immune function, and intermicrobial signaling, etc. SCFAs emerge as pivotal risk factors influencing CKD's development and prognosis. This paper review elucidates the impact of gut microbial metabolites, specifically SCFAs, on CKD, highlighting their role in modulating host inflammatory responses, oxidative stress, cellular autophagy, the immune milieu, and signaling cascades. An in-depth comprehension of the interplay between SCFAs and kidney disease pathogenesis may pave the way for their utilization as biomarkers for CKD progression and prognosis or as novel adjunctive therapeutic strategies.

The Effect and Mechanism of Oleanolic Acid in the Treatment of Metabolic Syndrome and Related Cardiovascular Diseases

Metabolic syndromes (MetS) and related cardiovascular diseases (CVDs) pose a serious threat to human health. MetS are metabolic disorders characterized by obesity, dyslipidemia, and hypertension, which increase the risk of CVDs' initiation and development. Although there are many availabile drugs for treating MetS and related CVDs, some side effects also occur. Considering the low-level side effects, many natural products have been tried to treat MetS and CVDs. A five-cyclic triterpenoid natural product, oleanolic acid (OA), has been reported to have many pharmacologic actions such as anti-hypertension, anti-hyperlipidemia, and liver protection. OA has specific advantages in the treatment of MetS and CVDs. OA achieves therapeutic effects through a variety of pathways, attracting great interest and playing a vital role in the treatment of MetS and CVDs. Consequently, in this article, we aim to review the pharmacological actions and potential mechanisms of OA in treating MetS and related CVDs.

Role of advanced glycation end products in diabetic vascular injury: molecular mechanisms and therapeutic perspectives

BACKGROUND

In diabetic metabolic disorders, advanced glycation end products (AGEs) contribute significantly to the development of cardiovascular diseases (CVD).

AIMS

This comprehensive review aims to elucidate the molecular mechanisms underlying AGE-mediated vascular injury.

CONCLUSIONS

We discuss the formation and accumulation of AGEs, their interactions with cellular receptors, and the subsequent activation of signaling pathways leading to oxidative stress, inflammation, endothelial dysfunction, smooth muscle cell proliferation, extracellular matrix remodeling, and impaired angiogenesis. Moreover, we explore potential therapeutic strategies targeting AGEs and related pathways for CVD prevention and treatment in diabetic metabolic disorders. Finally, we address current challenges and future directions in the field, emphasizing the importance of understanding the molecular links between AGEs and vascular injury to improve patient outcomes.

Effect of alpha-lipoic acid and caffeine-loaded chitosan nanoparticles on obesity and its complications in liver and kidney in rats

The present work investigated the effect of α-lipoic acid (ALA) and caffeine-loaded chitosan nanoparticles (CAF-CS NPs) on obesity and its hepatic and renal complications in rats. Rats were divided into control, rat model of obesity induced by high fat diet (HFD), and obese rats treated with ALA and/or CAF-CS NPs. At the end of the experiment, the activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP) and the levels of urea, creatinine, interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) were determined in the sera of animals. In addition, malondialdehyde (MDA), nitric oxide (NO), and reduced glutathione (GSH) were measured in hepatic and renal tissues. Renal Na+, K+-ATPase was assessed. The histopathological changes were examined in the hepatic and renal tissues. Obese rats showed a significant increase in AST, ALT, ALP, urea, and creatinine. This was associated with a significant increase in IL-1β, TNF-α, MDA, and NO. A significant decrease in hepatic and renal GSH and renal Na+, K+-ATPase activity was recorded in obese rats. Obese rats also showed histopathological alterations in hepatic and renal tissues. Treatment with ALA and/or CAF-CS NPs reduced the weight of obese rats and ameliorated almost all the hepatic and renal biochemical and histopathological changes induced in obese rats. In conclusion, the present findings indicate that ALA and/or CAF-CS NPs offered an effective therapy against obesity induced by HFD and its hepatic and renal complications. The therapeutic effect of ALA and CAF-CS NPs could be mediated through their antioxidant and anti-inflammatory properties.

Ox-LDL aggravates contrast-induced injury of renal tubular epithelial cells

Hypercholesterolemia can aggravate contrast-induced acute kidney injury, and the exacerbation of renal tubular epithelial cell (RTEC) injury is a major cause. However, the exact mechanisms remain obscure. Mitophagy, a type of autophagy, selectively eliminates damaged mitochondria and reduces mitochondrial oxidative stress, which is strongly implicated in cell homeostasis and acute kidney injury. Oxidized low-density lipoprotein (Ox-LDL) is accumulated in hypercholesterolemia and has a cytotoxic effect. This study aimed to determine whether and how ox-LDL exacerbates contrast-induced injury in RTECs and to further explore whether PINK1/Parkin-dependent mitophagy is involved in this process. Iohexol and ox-LDL were used alone or in combination to treat HK-2 cells. Rapamycin pretreatment was utilized to enhance mitophagy. Cell viability, apoptosis, mitochondrial membrane potential (MMP) and mitochondrial reactive oxygen species (mtROS) were detected by cell counting kit-8, TUNEL staining, JC-1 kit and MitoSOX fluorescence, respectively. The expression of mitophagy-related proteins (including PINK1, Parkin, and so on) and cleaved caspase-3 was confirmed by western blot. Colocalization of MitoTracker-labeled mitochondria and LysoTracker-labeled lysosomes was observed by fluorescence microscopy to evaluate mitophagy. The results of our study showed that ox-LDL aggravated MMP decline, mtROS release and apoptosis in iohexol-treated HK-2 cells, accompanied by a further increased autophagy level. Enhancement of PINK1/Parkin-dependent mitophagy by rapamycin alleviated apoptosis and mitochondrial injury in HK-2 cells in response to iohexol under ox-LDL condition. Therefore, our findings indicate that ox-LDL aggravates contrast-induced injury of RTECs by increasing mitochondrial damage and mitochondrial oxidative stress, which may be associated with the relative insufficiency of PINK1/Parkin-dependent mitophagy.

The balanced unsaturated fatty acid supplement constituted by woody edible oils improved lipid metabolism and gut microbiota in high-fat diet mice

The dietary intervention has demonstrated effectiveness in improving hyperlipidemia and obesity. Woody edible oils are rich in unsaturated fatty acids (UFAs) that could positively affect lipid metabolism. In this study, the blended oil (BLO), a balanced UFA supplement, constituted by Zanthoxylum bungeanum (Chinese Red Pepper) seed oil, walnut (Juglans regia) oil, camellia (Camema oleifera) seed oil and perilla (Perilla frutescens) seed oil was established referring to the Chinese dietary reference intakes, in which the ratios of monounsaturated/polyunsaturated fatty acids and ω-6/ω-3 polyunsaturated fatty acids were 1:1 and 4:1, respectively. The BLO was administrated to KM mice fed a high-fat diet (HFD) by gavage every day at a dose of 3.0 mL/kg·bw for 10 weeks to assess its effects on serum lipid levels, liver antioxidant activities and gut microbial composition. The results showed that the BLO improved hepatic steatosis, liver oxidative stress, and serum lipid levels. Additionally, there was an increased abundance of Lactobacillus, Allobaculum, and Blautia, along with a decreased abundance of Staphylococcus in cecal contents. These changes were found to be positively correlated with the metabolic improvements, as indicated by Spearman's correlation analysis. These findings implied the practicality of the balanced unsaturated fatty acid consumption in preventing hyperlipidemia and obesity.

Valproate-Induced Metabolic Syndrome

Valproic acid (VPA) and its salts (sodium calcium magnesium and orotic) are psychotropic drugs that are widely used in neurology and psychiatry. The long-term use of VPA increases the risk of developing adverse drug reactions (ADRs), among which metabolic syndrome (MetS) plays a special role. MetS belongs to a cluster of metabolic conditions such as abdominal obesity, high blood pressure, high blood glucose, high serum triglycerides, and low serum high-density lipoprotein. Valproate-induced MetS (VPA-MetS) is a common ADR that needs an updated multidisciplinary approach to its prevention and diagnosis. In this review, we consider the results of studies of blood (serum and plasma) and the urinary biomarkers of VPA-MetS. These metabolic biomarkers may provide the key to the development of a new multidisciplinary personalized strategy for the prevention and diagnosis of VPA-MetS in patients with neurological diseases, psychiatric disorders, and addiction diseases.

Modified Signaling of Membrane Formyl Peptide Receptors in NADPH-Oxidase Regulation in Obesity-Resistant Mice

The signaling of membrane receptors is modified in obesity characterized by low-grade inflammation. The obesity-resistant state of organisms is poorly understood. We analyzed the generation of reactive oxygen species (ROS) initiated though membrane formyl peptide receptors (Fpr1, Fpr2) in bone-marrow granulocytes of obesity-resistant mice (ORM). A chemiluminescence assay was used to assess NADPH-oxidase-related intensity of ROS generation. ORM were chosen from animals that received high-fat diets and had metric body parameters as controls (standard diet). High spontaneous ROS production was observed in ORM cells. The EC50 for responses to bacterial or mitochondrial peptide N-formyl-MLF was higher in ORM with and without inflammation vs. the same control groups, indicating an insignificant role of high-affinity Fpr1. Increased responses to synthetic peptide WKYMVM (Fpr2 agonist) were observed in controls with acute inflammation, but they were similar in other groups. Fpr2 was possibly partially inactivated in ORM owing to the inflammatory state. Weakened Fpr1 and Fpr2 signaling via MAPKs was revealed in ORM using specific inhibitors for p38, ERK1/2, and JNK. P38 signaling via Fpr2 was lower in ORM with inflammation. Thus, a high-fat diet modified FPRs' role and suppressed MAPK signaling in NADPH-oxidase regulation in ORM. This result can be useful to understand the immunological features of obesity resistance.

The mechanisms of glycolipid metabolism disorder on vascular injury in type 2 diabetes

Patients with diabetes have severe vascular complications, such as diabetic nephropathy, diabetic retinopathy, cardiovascular disease, and neuropathy. Devastating vascular complications lead to increased mortality, blindness, kidney failure, and decreased overall quality of life in people with type 2 diabetes (T2D). Glycolipid metabolism disorder plays a vital role in the vascular complications of T2D. However, the specific mechanism of action remains to be elucidated. In T2D patients, vascular damage begins to develop before insulin resistance and clinical diagnosis. Endothelial dysregulation is a significant cause of vascular complications and the early event of vascular injury. Hyperglycemia and hyperlipidemia can trigger inflammation and oxidative stress, which impair endothelial function. Furthermore, during the pathogenesis of T2D, epigenetic modifications are aberrant and activate various biological processes, resulting in endothelial dysregulation. In the present review, we provide an overview and discussion of the roles of hyperglycemia- and hyperlipidemia-induced endothelial dysfunction, inflammatory response, oxidative stress, and epigenetic modification in the pathogenesis of T2D. Understanding the connections of glucotoxicity and lipotoxicity with vascular injury may reveal a novel potential therapeutic target for diabetic vascular complications.

Coix Seed-Based Milk Fermented With Limosilactobacillus reuteri Improves Lipid Metabolism and Gut Microbiota in Mice Fed With a High-Fat Diet

The aim of this study was to investigate the effects of coix seed-based milk (CSM) fermented with Limosilactobacillus reuteri (L. reuteri) on dyslipidemia and the composition of the intestinal microbiota in high fat diet (HFD)-fed mice. Changes in the body weight, serum lipid levels, activities of hepatic oxidative stress factors, expression of lipid-related genes, and composition of the intestinal microbiota of HFD-fed mice after supplementation with CSM were determined. The results showed that intake of CSM reduced the body weight gain as well as serum total cholesterol (TC), triglyceride (TG), and low-density lipoprotein cholesterol (LDL-C) levels, and increased the high-density lipoprotein cholesterol (HDL-C) levels in the mice. Meanwhile, supplementation with CSM could relieve liver oxidative stress, down-regulate the expression of genes related to lipid synthesis, and prevent liver fat accumulation in mice fed with HFD. The 16S rRNA sequencing of the intestinal microbiota showed that CSM regulated the gut microbiota community structure at different taxonomic levels, and reversed gut dysbiosis induced by HFD. The relative abundance of Muribaculaceae, Lachnospiraceae, Dubosiella and Akkermansia which are negatively correlated with blood lipid levels were significantly increased by the intervention of CSM, while the relative abundance of Desulfovibrionaceae, Ruminococca-ceae_UCG-014, Psychrobacter, and Staphylococcus which have positive correlation with blood lipid levels were significantly decreased. These results indicated that CSM might serve as a novel and promising dietary supplement for ameliorating hyperlipidemia and intestinal microbiota disorders caused by HFDs.

Protective effects of E Se tea extracts against alcoholic fatty liver disease induced by high fat/alcohol diet: In vivo biological evaluation and molecular docking study

BACKGROUND

With the development of economy and increased workload, chronic a high-fat/alcohol diet intake may lead to alcoholic fatty liver disease (AFLD), which is considered as a crucial health problem worldwide. E Se tea is produced of the leaves and leaf buds of Malus toringoides (Rehd.) Hughes in Tibet and has human health benefits with anti-hyperglycemia, hypertension, and hyperlipidemia effects.

PURPOSE

The objective of this work was to investigate the protective effect of aqueous-ethanol and hot-water extracts of E Se tea against chronic high-fat/alcohol diet induced AFLD rats.

METHODS

Firstly, to determine the chemical profiling of E Se tea extracts, UHPLC-ESI-HRMS analysis was conducted. Secondly, Sprague-Dawley male rats were used to establish the AFLD animal model by feeding with high-fat/alcohol diet. The animals were treated with E Se tea extracts for 12 weeks. Serum parameters were determined, histologic sections were prepared, and activities of enzymes related to inflammatory response and lipid metabolism imbalance were analyzed. The underlying mechanisms of E Se tea extracts alleviating AFLD were analyzed by immunofluorescence staining and Western blotting analysis. Lastly, key targets of 11-MT against AFLD were verified through molecular docking.

RESULTS

In this study, seven main compounds were confirmed or tentatively identified in E Se tea extracts by UHPLC-ESI-HRMS. The results revealed that both the extracts could reverse histopathological steatotic alternation of the liver and reduced the activity of liver damage markers (ALT, AST). E Se tea extracts mitigated oxidative stress by inhibiting CYP2E1 protein and lipid peroxidation parameters (MDA), but enhancing the endogenous antioxidants (CAT, GSH, SOD). Moreover, E Se tea extracts ameliorated inflammation by restraining the activation of NF-κB, consequently releasing the expression of proinflammatory cytokines (TNF-α, IL-6, IL-1β, COX-2 and iNOS). Subsequently, E Se tea extracts reduced hepatocyte apoptosis by increasing capase-9, caspase-3 and Bax protein expression but decreasing Bcl-2 protein expression. Furthermore, E Se tea extracts improved metabolism imbalance by stimulating AMPK/SREBP1/FAS and PPAR-α/CPT1 signaling pathway by regulating lipid metabolism parameters (TC, TG, HDL-C, LHD-C). Furthermore, molecular docking results indicated that 7 chemical constituents of E Se tea extracts had strong docking affinity with 4 key target proteins (AMPK, PPAR-α, NF-кB and Caspase-9).

CONCLUSION

E Se tea ameliorated AFLD through ameliorating inflammatory response, apoptosis, and lipid metabolism imbalance.

Role of anatomical location, cellular phenotype and perfusion of adipose tissue in intermediary metabolism: A narrative review

It is well-established that adipose tissue accumulation is associated with insulin resistance through multiple mechanisms. One major metabolic link is the classical Randle cycle: enhanced release of free fatty acids (FFA) from hydrolysis of adipose tissue triglycerides impedes insulin-mediated glucose uptake in muscle tissues. Less well studied are the different routes of this communication. First, white adipose tissue depots may be regionally distant from muscle (i.e., gluteal fat and diaphragm muscle) or contiguous to muscle but separated by a fascia (Scarpa's fascia in the abdomen, fascia lata in the thigh). In this case, released FFA outflow through the venous drainage and merge into arterial plasma to be transported to muscle tissues. Next, cytosolic triglycerides can directly, i.e., within the cell, provide FFA to myocytes (but also pancreatic ß-cells, renal tubular cells, etc.). Finally, adipocyte layers or lumps may be adjacent to, but not anatomically segregated, from muscle, as is typically the case for epicardial fat and cardiomyocytes. As regulation of these three main delivery paths is different, their separate contribution to substrate competition at the whole-body level is uncertain. Another important link between fat and muscle is vascular. In the resting state, blood flow is generally higher in adipose tissue than in muscle. In the insulinized state, fat blood flow is directly related to whole-body insulin resistance whereas muscle blood flow is not; consequently, fractional (i.e., flow-adjusted) glucose uptake is stimulated in muscle but not fat. Thus, reduced blood supply is a major factor for the impairment of in vivo insulin-mediated glucose uptake in both subcutaneous and visceral fat. In contrast, the insulin resistance of glucose uptake in resting skeletal muscle is predominantly a cellular defect.

Skeletal muscle energetics in patients with moderate to advanced kidney disease

Sarcopenia, defined as decrease in muscle function and mass, is common in patients with moderate to advanced chronic kidney disease (CKD) and is associated with poor clinical outcomes. Muscle mitochondrial dysfunction is proposed as one of the mechanisms underlying sarcopenia. Patients with moderate to advanced CKD have decreased muscle mitochondrial content and oxidative capacity along with suppressed activity of various mitochondrial enzymes such as mitochondrial electron transport chain complexes and pyruvate dehydrogenase, leading to impaired energy production. Other mitochondrial abnormalities found in this population include defective beta-oxidation of fatty acids and mitochondrial DNA mutations. These changes are noticeable from the early stages of CKD and correlate with severity of the disease. Damage induced by uremic toxins, oxidative stress, and systemic inflammation has been implicated in the development of mitochondrial dysfunction in CKD patients. Given that mitochondrial function is an important determinant of physical activity and performance, its modulation is a potential therapeutic target for sarcopenia in patients with kidney disease. Coenzyme Q, nicotinamide, and cardiolipin-targeted peptides have been tested as therapeutic interventions in early studies. Aerobic exercise, a well-established strategy to improve muscle function and mass in healthy adults, is not as effective in patients with advanced kidney disease. This might be due to reduced expression or impaired activation of peroxisome proliferator-activated receptor-gamma coactivator 1α, the master regulator of mitochondrial biogenesis. Further studies are needed to broaden our understanding of the pathogenesis of mitochondrial dysfunction and to develop mitochondrial-targeted therapies for prevention and treatment of sarcopenia in patients with CKD.

Integrated analysis of potential gene crosstalk between non-alcoholic fatty liver disease and diabetic nephropathy

BACKGROUND

Growing evidence indicates that non-alcoholic fatty liver disease (NAFLD) is related to the occurrence and development of diabetic nephropathy (DN). This bioinformatics study aimed to explore optimal crosstalk genes and related pathways between NAFLD and DN.

METHODS

Gene expression profiles were downloaded from Gene Expression Omnibus. CIBERSORT algorithm was employed to analyze the similarity of infiltrating immunocytes between the two diseases. Protein-protein interaction (PPI) co-expression network and functional enrichment analysis were conducted based on the identification of common differentially expressed genes (DEGs). Least absolute shrinkage and selection operator (LASSO) regression and Boruta algorithm were implemented to initially screen crosstalk genes. Machine learning models, including support vector machine, random forest model, and generalized linear model, were utilized to further identify the optimal crosstalk genes between DN and NAFLD. An integrated network containing crosstalk genes, transcription factors, and associated pathways was developed.

RESULTS

Four gene expression datasets, including GSE66676 and GSE48452 for NAFLD and GSE30122 and GSE1009 for DN, were involved in this study. There were 80 common DEGs between the two diseases in total. The PPI network built with the 80 common genes included 77 nodes and 83 edges. Ten optimal crosstalk genes were selected by LASSO regression and Boruta algorithm, including CD36, WIPI1, CBX7, FCN1, SLC35D2, CP, ZDHHC3, PTPN3, LPL, and SPP1. Among these genes, LPL and SPP1 were the most significant according to NAFLD-transcription factor network. Five hundred twenty-nine nodes and 1,113 edges comprised the PPI network of activated pathway-gene. In addition, 14 common pathways of these two diseases were recognized using Gene Ontology (GO) analysis; among them, regulation of the lipid metabolic process is closely related to both two diseases.

CONCLUSIONS

This study offers hints that NAFLD and DN have a common pathogenesis, and LPL and SPP1 are the most relevant crosstalk genes. Based on the common pathways and optimal crosstalk genes, our proposal carried out further research to disclose the etiology and pathology between the two diseases.

Polymorphism rs10105606 of LPL as a Novel Risk Factor for Microalbuminuria

Introduction

An important clinical feature of metabolic syndrome is abdominal obesity. Microalbuminuria is important in predicting the risk of cardiovascular and renal complications in abdominal obesity patients. However, the association between microalbuminuria polymorphism and abdominal obesity has not been conducted. The objective of this study is to analyze the genetic polymorphism of microalbuminuria in participants with metabolically unhealthy obesity (MUO).

Methods

Among 1325 MUO participants, we identified genomic loci underlying those with microalbuminuria, compared to those without microalbuminuria. Single nucleotide polymorphisms (SNPs) were selected with P < 1 × 10⁻⁵ from the Manhattan plot. Multivariable linear regression and analysis of variance were used to analyze the association between different SNP genotypes and microalbuminuria.

Results

The analysis showed homozygous participants for the risk allele A of rs10105606 and Affx-31885823 had 1.978-fold risk and 1.921-fold increased risk of microalbuminuria, respectively. Heterozygous distribution of rs117180252, rs10105606, and Affx-31885823 also increased the risk of microalbuminuria compared to the wild type. Further analysis showed Lipoprotein lipase (LPL), RN7SL87P, and RPL30P9 were the candidate genes associated with lipid metabolism and abdominal obesity.

Conclusion

In conclusion, LPL, RN7SL87P, and RPL30P9 minor allele carriers with abdominal obesity are more susceptible to microalbuminuria, explaining the inter-individual differences of microalbuminuria in MUO patients.

Rhus chinensis Mill. Fruits Ameliorate Hepatic Glycolipid Metabolism Disorder in Rats Induced by High Fat/High Sugar Diet

Hepatic glycolipid metabolism disorder is considered as one of the key factors in the pathogenesis of many chronic diseases. The objective of this study was to investigate the protective effect and underlying mechanisms of Rhus chinensis Mill. fruits against hepatic glycolipid metabolic disorders in rats induced by a high fat/high sugar diet. Results showed that ethanol extract, especially at a dose of 600 mg/kg b.w., could effectively ameliorate glycolipid metabolic disorders in rats. The biochemical indexes, including CAT, GSH and HOMA-IR, were significantly improved by the administration of ethanol extract. Immunohistochemistry and Western blot analysis revealed that ethanol extract up-regulated the expression levels of PI3K/AKT, PPAR-α, and the phosphorylation of IRS1 and AMPK proteins, and down-regulated the expressions of SREBP-1 and FAS proteins in the liver, which are closely related to hepatic glycolipid metabolism. Those findings suggested that R. chinensis Mill. fruits could be developed as functional foods and/or nutraceuticals for preventing or controlling some chronic diseases related to hepatic glycolipid metabolism disorder.

Oxidized LDL Is Associated with eGFR Decline in Proteinuric Diabetic Kidney Disease: A Cohort Study

Diabetic kidney disease (DKD) is a highly heterogenous disease, including the proteinuric and the nonproteinuric pattern. Oxidized low-density lipoprotein (ox-LDL) is progressively increased in DKD and causes direct damage to kidney tubular epithelial cells through a mechanism similar to that underlying the deleterious effect of lipid peroxides in the vascular endothelium. We aimed to examine the association between plasma ox-LDL cholesterol and clinical endpoints in DKD patients. Ninety-one patients with established proteinuric DKD and diabetic retinopathy were enrolled and prospectively followed for 10 years or the occurrence of death, or at least 30% decline in eGFR, or progression to end-stage kidney disease (ESKD) requiring renal replacement therapy (primary outcome). At the end of the study, both eGFR and proteinuria were reassessed. Secondary outcomes of the study were the percentage change in eGFR and proteinuria over time for each patient. At baseline, patients were divided into 2 groups according to the median ox-LDL value (i.e., below or equal and above 66.22 U/L). Both Kaplan-Meier curves (p = 0.001, log-rank test) and univariate Cox regression analysis showed that high ox-LDL was associated with the primary outcome (HR = 3.42, 95%CI = 1.55 − 7.56, p = 0.002). After adjustment for various well-known cofounders, multivariate Cox analysis showed that the association between increased circulating ox-LDL levels and the composite kidney endpoint remained significant (HR = 2.87, 95%CI = 1.14–7.20, p = 0.025). Regarding the secondary outcome of eGFR decline, the assessment of areas under the curves (AUC) showed that ox-LDL outperformed several cofounding factors (AUC 71%, 95%CI = 0.59 − 0.83, p = 0.001) and had better accuracy to predict deterioration of eGFR over time than baseline proteinuria (AUC 67%, 95%CI = 0.54 − 0.79, p = 0.014). Increased ox-LDL might be associated with disease progression in proteinuric DKD.

CER-001 ameliorates lipid profile and kidney disease in a mouse model of familial LCAT deficiency

OBJECTIVE

CER-001 is an HDL mimetic that has been tested in different pathological conditions, but never with LCAT deficiency. This study was designed to investigate whether the absence of LCAT affects the catabolic fate of CER-001, and to evaluate the effects of CER-001 on kidney disease associated with LCAT deficiency.

METHODS

Lcat^-/- and wild-type mice received CER-001 (2.5, 5, 10 mg/kg) intravenously for 2 weeks. The plasma lipid/ lipoprotein profile and HDL subclasses were analyzed. In a second set of experiments, Lcat^-/- mice were injected with LpX to induce renal disease and treated with CER-001 and then the plasma lipid profile, lipid accumulation in the kidney, albuminuria and glomerular podocyte markers were evaluated.

RESULTS

In Lcat^-/- mice a decrease in total cholesterol and triglycerides, and an increase in HDL-c was observed after CER-001 treatment. While in wild-type mice CER-001 entered the classical HDL remodeling pathway, in the absence of LCAT it disappeared from the plasma shortly after injection and ended up in the kidney. In a mouse model of renal disease in LCAT deficiency, treatment with CER-001 at 10 mg/kg for one month had beneficial effects not only on the lipid profile, but also on renal disease, by limiting albuminuria and podocyte dysfunction.

CONCLUSIONS

Treatment with CER-001 ameliorates the dyslipidemia typically associated with LCAT deficiency and more importantly limits renal damage in a mouse model of renal disease in LCAT deficiency. The present results provide a rationale for using CER-001 in FLD patients.

RNA Interference Targeting Liver Angiopoietin-Like Protein 3 Protects from Nephrotic Syndrome in a Rat Model Via Amelioration of Pathologic Hypertriglyceridemia

Nephrotic syndrome (NS) is associated with metabolic perturbances including profound dyslipidemia characterized by hypercholesterolemia and hypertriglyceridemia. A major underlying mechanism of hypertriglyceridemia in NS is lipoprotein lipase (LPL) deficiency and dysfunction. There is emerging evidence that elevated angiopoietin-like protein 3 (ANGPTL3), an LPL inhibitor that is primarily expressed and secreted by hepatocytes, may be in part responsible for these findings. Furthermore, there is evidence pointing to the contribution of ANGPTL3 to the pathogenesis of proteinuria in NS. Therefore, we hypothesized that inhibition of hepatic ANGPTL3 by RNA interference will ameliorate dyslipidemia and other symptoms of NS and pave the way for a new therapeutic strategy. To this end, we used a subcutaneously delivered, GalNAc (N-Acetylgalactosamine)-conjugated small interfering RNA (siRNA) to selectively target and suppress liver Angptl3 in rats with puromycin-induced NS, which exhibits clinical features of NS including proteinuria, hypoalbuminemia, hyperlipidemia, and renal histologic abnormalities. The study demonstrated that siRNA-mediated knockdown of the liver Angptl3 relieved its inhibitory effect on LPL and significantly reduced hypertriglyceridemia in nephrotic rats. This was accompanied by diminished proteinuria and hypoalbuminemia, which are the hallmarks of NS, and significant attenuation of renal tissue inflammation and oxidative stress. Taken together, this study confirmed the hypothesis that suppression of Angptl3 is protective in NS and points to the possibility that the use of RNA interference to suppress hepatic Angptl3 can serve as a novel therapeutic strategy for NS. SIGNIFICANCE STATEMENT: The current standard of care for mitigating nephrotic dyslipidemia in nephrotic syndrome is statins therapy. However, the efficacy of statins and its safety in the context of impaired kidney function is not well established. Here, we present an alternate therapeutic approach by using siRNA targeting Angptl3 expressed in hepatocytes. As the liver is the major source of circulating Angptl3, siRNA treatment reduced the profound hypertriglyceridemia in a rat model of nephrotic syndrome and was also effective in improving kidney and cardiac function.

Triglycerides to high-density lipoprotein cholesterol ratio is superior to triglycerides and other lipid ratios as an indicator of increased urinary albumin-to-creatinine ratio in the general population of China: a cross-sectional study

Background

Dyslipidemia contributes to the pathogenesis of renal dysfunction. Previous research demonstrated that triglycerides (TG), instead of other individual lipid indexes, has a significant link with elevated urinary albumin-to-creatinine ratio (UACR). However, it is unclear whether lipid ratios are superior indicators of increased UACR compared with TG. This research is to determine whether there are close relationships of lipid ratios with UACR in a general population.

Methods

35,751 participants from seven centers across China were enrolled. UACR equal or higher than 30 mg/g was recognized as increased albuminuria. The associations of TG, low-density lipoprotein cholesterol (LDL-C)/ high-density lipoprotein cholesterol (HDL-C), TG/HDL-C and non-high-density lipoprotein cholesterol (non-HDL-C)/HDL-C with increased UACR were evaluated by linear and logistic regression analyses in females and males separately.

Results

There were 3692 (14.8%) female subjects, and 1307 (12.0%) male subjects characterized as having increased UACR. There were significantly differences in TG/HDL-C and non-HDL-C/HDL-C between the normal UACR group and the increased UACR group, while LDL-C/HDL-C was not. Furthermore, linear regression analysis was implemented and showed that TG and TG/HDL-C were both positively related to UACR even after a variety of potential confounders were adjusted regardless of sexes, while the correlation between non-HDL-C/HDL-C and elevated UACR were only significant in females. Further analyses utilizing logistic regression demonstrated that compared with non-HDL-C/HDL-C and TG, TG/HDL-C showed the strongest association with increased UACR (quartile 1 of TG/HDL-C as a reference; OR [95% CI] of quartile 4: 1.28 [1.13–1.44] in women, 1.24 [1.02–1.50] in men) after fully adjusting for potential confounding factors. Stratified analyses revealed that in males who were overweight and in females who were overweight or over 55 years or had prediabetes or prehypertension, TG/HDL-C had significant associations with abnormal UACR.

Conclusions

Compared with TG and other routine lipid ratios, TG/HDL-C is a superior indicator for increased UACR.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-021-01442-8.

Effects of High Glucose and Lipotoxicity on Diabetic Podocytes

Glomerular podocytes are highly differentiated cells that cover glomerular capillaries from the outside and have a characteristic morphology with numerous foot processes. The formation of slit membranes between the foot processes serves as a final filtration barrier for urine filtration from the blood. Podocyte damage causes disruption of the slit membrane, subsequent proteinuria and finally glomerulosclerosis, which is a common pathway in various types of chronic kidney disease (CKD). In recent years, there has been an increase in diabetes, due to rapid lifestyle changes, which is the main cause of CKD. Therefore, understanding the effect of diabetic status on podocytes is of great importance to establish a strategy for preventing CKD progression. In this review, we summarize altered glucose and lipid metabolism in diabetic podocytes and also discuss the reversibility of the changes in podocyte phenotype.

Dyslipidemia in Kidney Disorders: Perspectives on Mitochondria Homeostasis and Therapeutic Opportunities

To excrete body nitrogen waste and regulate electrolyte and fluid balance, the kidney has developed into an energy factory with only second to the heart in mitochondrial content in the body to meet the high-energy demand and regulate homeostasis. Energy supply from the renal mitochondria majorly depends on lipid metabolism, with programed enzyme systems in fatty acid β-oxidation and Krebs cycle. Renal mitochondria integrate several metabolic pathways, including AMPK/PGC-1α, PPARs, and CD36 signaling to maintain energy homeostasis for dynamic and static requirements. The pathobiology of several kidney disorders, including diabetic nephropathy, acute and chronic kidney injuries, has been primarily linked to impaired mitochondrial bioenergetics. Such homeostatic disruption in turn stimulates a pathological adaptation, with mitochondrial enzyme system reprograming possibly leading to dyslipidemia. However, this alteration, while rescuing oncotic pressure deficit secondary to albuminuria and dissipating edematous disorder, also imposes an ominous lipotoxic consequence. Reprograming of lipid metabolism in kidney injury is essential to preserve the integrity of kidney mitochondria, thereby preventing massive collateral damage including excessive autophagy and chronic inflammation. Here, we review dyslipidemia in kidney disorders and the most recent advances on targeting mitochondrial energy metabolism as a therapeutic strategy to restrict renal lipotoxicity, achieve salutary anti-edematous effects, and restore mitochondrial homeostasis.

Sterol-O-acyltransferase-1 has a role in kidney disease associated with diabetes and Alport syndrome

Defective cholesterol metabolism primarily linked to reduced ATP-binding cassette transporter A1 (ABCA1) expression is closely associated with the pathogenesis and progression of kidney diseases, including diabetic kidney disease and Alport Syndrome. However, whether the accumulation of free or esterified cholesterol contributes to progression in kidney disease remains unclear. Here, we demonstrate that inhibition of sterol-O-acyltransferase-1 (SOAT1), the enzyme at the endoplasmic reticulum that converts free cholesterol to cholesterol esters, which are then stored in lipid droplets, effectively reduced cholesterol ester and lipid droplet formation in human podocytes. Furthermore, we found that inhibition of SOAT1 in podocytes reduced lipotoxicity-mediated podocyte injury in diabetic kidney disease and Alport Syndrome in association with increased ABCA1 expression and ABCA1-mediated cholesterol efflux. In vivo, Soat1 deficient mice did not develop albuminuria or mesangial expansion at 10-12 months of age. However, Soat1 deficiency/inhibition in experimental models of diabetic kidney disease and Alport Syndrome reduced cholesterol ester content in kidney cortices and protected from disease progression. Thus, targeting SOAT1-mediated cholesterol metabolism may represent a new therapeutic strategy to treat kidney disease in patients with diabetic kidney disease and Alport Syndrome, like that suggested for Alzheimer's disease and cancer treatments.

Estrogen-progestin oral contraceptive and nicotine exposure synergistically confers cardio-renoprotection in female Wistar rats

Approximately fifty percent of premenopausal women who smoke cigarettes or on nicotine replacement therapy are also on hormonal contraceptives, especially oral estrogen-progestin. Oral estrogen-progestin therapy has been reported to promote insulin resistance (IR) which causes lipid influx into non-adipose tissue and impairs Na⁺/K⁺ -ATPase activity, especially in the heart and kidney. However, the effects of nicotine on excess lipid and altered Na⁺/K⁺ -ATPase activity associated with the use of estrogen-progestin therapy have not been fully elucidated. This study therefore aimed at investigating the effect of nicotine on cardiac and renal lipid influx and Na⁺/K⁺ -ATPase activity during estrogen-progestin therapy. Twenty-four female Wistar rats grouped into 4 (n = 6/group) received (p.o.) vehicle, nicotine (1.0 mg/kg) with or without estrogen-progestin steroids (1.0 μg ethinyl estradiol and 5.0 μg levonorgestrel) and estrogen-progestin only daily for 6 weeks. Data showed that estrogen-progestin treatment or nicotine exposure caused IR, hyperinsulinemia, increased cardiac and renal uric acid, malondialdehyde, triglyceride, glycogen synthase kinase-3, plasminogen activator inhibitor-1, reduced bilirubin and circulating estradiol. Estrogen-progestin treatment led to decreased cardiac Na⁺/K⁺-ATPase activity while nicotine did not alter Na⁺/K⁺-ATPase activity but increased plasma and tissue cotinine. Renal Na⁺/K⁺-ATPase activity was not altered by the treatments. However, all these alterations were reversed following combined administration of oral estrogen-progestin therapy and nicotine. The present study therefore demonstrates that oral estrogen-progestin therapy and nicotine exposure synergistically prevents IR-linked cardio-renotoxicity with corresponding improvement in cardiac and renal lipid accumulation, oxidative stress, inflammation and Na⁺/K⁺-ATPase activity.

Beneficial Effects of Isoflavones in the Kidney of Obese Rats Are Mediated by PPAR-Gamma Expression

Several studies have demonstrated an important association between altered lipid metabolism and the development of kidney injury because of a high-fat diet. Fructose is also closely associated with renal injury. We opted for a combination of fructose and saturated fats in a diet (DH) that is a model known to induce renal damage in order to evaluate whether soy isoflavones could have promising use in the treatment of renal alterations. After two months of ingestion, there was an expansion of visceral fat, which was associated with long-term metabolic disorders, such as sustained hyperglycemia, insulin resistance, polyuria, dyslipidemia, and hypertension. Additionally, we found a decrease in renal blood flow and an increase in renal vascular resistance. Biochemical markers of chronic kidney disease were detected; there was an infiltration of inflammatory cells with an elevated expression of proinflammatory cytokines (tumor necrosis factor-α, interleukin (IL)-6, and IL-1β), the activation of the renin–angiotensin system, and oxidative/nitrosative stress. Notably, in rats exposed to the DH diet for 120 days, the concomitant treatment with isoflavones after 60 days was able to revert metabolic parameters, renal alterations, and oxidative/nitrosative stress. The beneficial effects of isoflavones in the kidney of the obese rats were found to be mediated by expression of peroxisome proliferator-activated receptor gamma (PPAR-γ).

Recent Progress on Lipid Intake and Chronic Kidney Disease

The incidence of chronic kidney disease (CKD) is associated with major abnormalities in circulating lipoproteins and renal lipid metabolism. This article elaborates on the mechanisms of CKD and lipid uptake abnormalities. The viewpoint we supported is that lipid abnormalities directly cause CKD, resulting in forming a vicious cycle. On the theoretical and experiment fronts, this inference has been verified by elaborately elucidating the role of lipid intake and accumulation as well as their influences on CKD. Taken together, these findings suggest that further understanding of lipid metabolism in CKD may lead to novel therapeutic approaches.

The C18:3n6/C22:4n6 ratio is a good lipid marker of chronic kidney disease (CKD) progression

Background

Chronic kidney disease (CKD) is a major challenge for public health due to increased risk of cardiovascular diseases (CVD) and premature death. The aim of this study was to determine the clinical picture of FA and the course of the pathophysiological mechanisms of CKD.

Methods

The study involved 149 patients with CKD and a control group including 43 people. Fatty acid profiles were investigated using gas chromatography. A total of 30 fatty acids and their derivatives were identified and quantified. The omega3, omega6, SFA, MUFA, and PUFA fatty acid contents were calculated. The correlation matrix was obtained for parameters relating to patients with CKD vs. FA, taking patients’ sex into consideration. The index C18:3n6/C22:4n6 was calculated according to the length of the treatment. Statistica 12.0 software (Tulsa, Oklahoma, USA) was used for the statistical analyses.

Results

The results showed decreased levels of total PUFA and increased concentrations of MUFA, including the activation of the palmitic and oleic acid pathway. An increase in the levels of n-6 9C22: 4n6 family fatty acids in all the patients and a reduction in the n-3 family (EPA, DHA) were observed. C18:3n6 was negatively correlated and C22:4n6 was positively correlated with the duration of the treatment. The index C18:3n6/C22:4n6 was defined as a new marker in the progression of the disease. Moreover, the index C18:3n6/ C22:4n6 was drastically decreased in later period. Nervonic acid was higher in the CKD group. In the group of men with CKD, there was a negative correlation between the excretion of K+, anthropometric measurements, and the levels of EPA and DHA.

Conclusions

The course of inflammation in CKD occurs through the decrease in PUFA and the synthesis of MUFA. The dominating cascade of changes is the elongation of GLA-C18:3n6 into DGLA-C20:3n6 and AA-C20:4n6. As CKD progresses, along with worsening anthropometrical parameters and increased secretion of potassium, the activity of Ʌ6-desaturase decreases, reducing the synthesis of EPA and DHA. The synthesis of AdA-C22:4n6 increases and the ratio C18:3n6/C22:4n6 drastically decreases after 5 years. This parameter can be used to diagnose disease progression.

Lipotoxicity and Diabetic Nephropathy: Novel Mechanistic Insights and Therapeutic Opportunities

Lipotoxicity is characterized by the ectopic accumulation of lipids in organs different from adipose tissue. Lipotoxicity is mainly associated with dysfunctional signaling and insulin resistance response in non-adipose tissue such as myocardium, pancreas, skeletal muscle, liver, and kidney. Serum lipid abnormalities and renal ectopic lipid accumulation have been associated with the development of kidney diseases, in particular diabetic nephropathy. Chronic hyperinsulinemia, often seen in type 2 diabetes, plays a crucial role in blood and liver lipid metabolism abnormalities, thus resulting in increased non-esterified fatty acids (NEFA). Excessive lipid accumulation alters cellular homeostasis and activates lipogenic and glycogenic cell-signaling pathways. Recent evidences indicate that both quantity and quality of lipids are involved in renal damage associated to lipotoxicity by activating inflammation, oxidative stress, mitochondrial dysfunction, and cell-death. The pathological effects of lipotoxicity have been observed in renal cells, thus promoting podocyte injury, tubular damage, mesangial proliferation, endothelial activation, and formation of macrophage-derived foam cells. Therefore, this review examines the recent preclinical and clinical research about the potentially harmful effects of lipids in the kidney, metabolic markers associated with these mechanisms, major signaling pathways affected, the causes of excessive lipid accumulation, and the types of lipids involved, as well as offers a comprehensive update of therapeutic strategies targeting lipotoxicity.

Roles of pattern recognition receptors in diabetic nephropathy

Diabetic nephropathy (DN) is currently the most common complication of diabetes. It is considered to be one of the leading causes of end-stage renal disease (ESRD) and affects many diabetic patients. The pathogenesis of DN is extremely complex and has not yet been clarified; however, in recent years, increasing evidence has shown the important role of innate immunity in DN pathogenesis. Pattern recognition receptors (PRRs) are important components of the innate immune system and have a significant impact on the occurrence and development of DN. In this review, we classify PRRs into secretory, endocytic, and signal transduction PRRs according to the relationship between the PRRs and subcellular compartments. PRRs can recognize related pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs), thus triggering a series of inflammatory responses, promoting renal fibrosis, and finally causing renal impairment. In this review, we describe the proposed role of each type of PRRs in the development and progression of DN.

Altered renal hemodynamics is associated with glomerular lipid accumulation in obese Dahl salt-sensitive leptin receptor mutant rats

The present study examined whether development of renal injury in the nondiabetic obese Dahl salt-sensitive leptin receptor mutant (SS^LepRmutant) strain is associated with elevations in glomerular filtration rate and renal lipid accumulation. Baseline mean arterial pressure at 6 wk of age was similar between Dahl salt-sensitive wild-type (SS_WT) and SS^LepRmutant rats. However, by 18 wk of age, the SS^LepRmutant strain developed hypertension, while the elevation in mean arterial pressure was not as severe in SS_WT rats (192 ± 4 and 149 ± 6 mmHg, respectively). At baseline, proteinuria was fourfold higher in SS^LepRmutant than SS_WT rats and remained elevated throughout the study. The early development of progressive proteinuria was associated with renal hyperfiltration followed by a decline in renal function over the course of study in the SS^LepRmutant compared with SS_WT rats. Kidneys from the SS^LepRmutant strain displayed more glomerulosclerosis and glomerular lipid accumulation than SS_WT rats. Glomeruli were isolated from the renal cortex of both strains at 6 and 18 wk of age, and RNA sequencing was performed to identify genes and pathways driving glomerular injury. We observed significant increases in expression of the influx lipid transporters, chemokine (C-X-C motif) ligand 16 (Cxcl16) and scavenger receptor and fatty acid translocase (Cd36), respectively, and a significant decrease in expression of the efflux lipid transporter, ATP-binding cassette subfamily A member 2 (Abca2; cholesterol efflux regulatory protein 2), in SS^LepRmutant compared with SS_WT rats at 6 and 18 wk of age, which were validated by RT-PCR analysis. These data suggest an association between glomerular hyperfiltration and glomerular lipid accumulation during the early development of proteinuria associated with obesity.

Impact of different ectopic fat depots on cardiovascular and metabolic diseases

A growing body of evidence is pointing out the pathophysiological role of fat accumulation in different organs. Ectopic fat depots within heart, liver, skeletal muscle, kidney, and pancreas as well as around blood vessels might be more associated to cardiometabolic risk than classical variables, such as body mass index. Among different mechanisms, lipid metabolism appears to be particularly influenced by ectopic fat depots. Indeed, intracellular accumulation of nonesterified fatty acids, and triglycerides promotes endoplasmic reticulum stress, mitochondrial uncoupling, oxidative stress, and altered membrane composition/function, finally promoting inflammatory response and cell death. The dysfunctional adipose tissue was shown to induce both local and systemic effects, with relevant clinical consequences. Epicardial fat and myocardial steatosis have been associated with the development of atrial fibrillation and ventricular dysfunction. Similarly perivascular adipose tissue appears to trigger atherosclerosis and hypertension. Nonalcoholic fatty liver disease has been recognized both as the hepatic manifestation of metabolic syndrome and as a cardiovascular (CV) risk factor. Importantly, the renal sinus fat emerged as a potential player in kidney dysfunction. Finally, both skeletal muscle and pancreatic fat depots have been indicated as potential endocrine modulators of insulin resistance. Considering the global rise in the prevalence of obesity, the understanding of mechanisms underlying ectopic fat accumulation represents an urgent need, with potential clinical implications for CV risk stratification. Here, we attempt to update the current knowledge of the different ectopic fat depots, focusing on underlying mechanisms and potential clinical implications.

CD36 identified by weighted gene co-expression network analysis as a hub candidate gene in lupus nephritis

Lupus nephritis (LN) is a severe manifestation of systemic lupus erythematosus (SLE), which often progresses to end-stage renal disease (ESRD) and ultimately leads to death. At present, there are no definitive therapies towards LN, so that illuminating the molecular mechanism behind the disease has become an urgent task for researchers. Bioinformatics has become a widely utilized method for exploring genes related to disease. This study set out to conduct weighted gene co-expression network analysis (WGCNA) and screen the hub gene of LN. We performed WGCNA on the microarray expression profile dataset of GSE104948 from the Gene Expression Omnibus (GEO) database with 18 normal and 21 LN samples of glomerulus. A total of 5,942 genes were divided into 5 co-expression modules, one of which was significantly correlated to LN. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted on the LN-related module, and the module was proved to be associated mainly with the activation of inflammation, immune response, cytokines, and immune cells. Genes in the most significant GO terms were extracted for sub-networks of WGNCA. We evaluated the centrality of genes in the sub-networks by Maximal Clique Centrality (MCC) method and CD36 was ultimately screened out as a hub candidate gene of the pathogenesis of LN. The result was verified by its differentially expressed level between normal and LN in GSE104948 and the other three multi-microarray datasets of GEO. Moreover, we further demonstrated that the expression level of CD36 is related to the WHO Lupus Nephritis Class of LN patients with the help of Nephroseq database. The current study proposed CD36 as a vital candidate gene in LN for the first time and CD36 may perform as a brand-new biomarker or therapeutic target of LN in the future.

FcgRIII Deficiency and FcgRIIb Defeciency Promote Renal Injury in Diabetic Mice

The immune system is involved in the development of diabetes complications and IgG Fc gamma receptors (FcgRs) are key immune receptors responsible for the effective control of both humoral and innate immunity. We investigated the effects of members of the FcgR superfamily into both the streptozotocin plus high fat-induced type 2 diabetes and high fat diet (HFD) models. FcgRIII^-/- diabetic mice and FcgRIIb^-/- diabetic mice had elevated levels of serum creatinine compared with wildtype (WT) diabetic mice. Renal histology of diabetic FcgRIII knockout and FcgRIIb knockout mice showed mesangial expansion and GBM thickening; the mechanistic study indicated a higher expression of TGF-β1, TNF-α, and p-NFκB-p65 compared with wild type mouse. The HFD mouse with FcgRIII knockout or FcgRIIb knockout had increased biochemical and renal injury factors, but oxLDL deposition was higher than in FcgRIII^-/- diabetic mice and FcgRIIb^-/- diabetic mice. In vitro we further examined the mechanism by which the Fc gamma receptor promoted renal injury and transfected glomerular mesangial cells (GMCs) with FcgRI siRNA attenuated the level of TGF-β1, TNF-α expression. In summary, FcgRI knockdown downregulated kidney inflammation and fibrosis and FcgRIIb knockout accelerated inflammation, fibrosis, and the anomalous deposition of oxLDL whereas FcgRIII deficiency failed to protect kidney from diabetic renal injury. These observations suggested that FcgRs might represent a novel target for the therapeutic intervention of diabetic nephropathy.

Post-weaning Exposure to High-Fat Diet Induces Kidney Lipid Accumulation and Function Impairment in Adult Rats

Aim: We investigated the kidney morphofunctional consequences of high-fat diet intake since post-weaning in adult rats.

Main Methods: Male Wistar rats were divided into two groups: ND (normal diet; n = 10) and HD (high-fat diet; n = 10). The high-fat diet was introduced post-weaned and animals were followed for 8 weeks.

Key Findings: HD group did not change body weight gain even though food consumption has decreased with no changes in caloric consumption. The HD group showed glucose intolerance and insulin resistance. The glomerular filtration rate (GFR) was decreased in vivo (ND: 2.8 ± 1.01; HD: 1.1 ± 0.14 ml/min) and in the isolated perfusion method (34% of decrease). Renal histological analysis showed a retraction in glomeruli and an increase in kidney lipid deposition (ND: 1.5 ± 0.17 HD: 5.9 ± 0.06%). Furthermore, the high-fat diet consumption increased the pro-inflammatory cytokines IL-6 (ND: 1,276 ± 203; HD: 1,982 ± 47 pg/mL/mg) and IL-1b (ND: 97 ± 12 HD: 133 ± 5 pg/mL/mg) without changing anti-inflammatory cytokine IL-10.

Significance: Our study provides evidence that high-fat diet consumption leads to renal lipid accumulation, increases inflammatory cytokines, induces glomeruli retraction, and renal dysfunction. These damages observed in the kidney could be associated with an increased risk to advanced CKD in adulthood suggesting that reduction of high-fat ingestion during an early period of life can prevent metabolic disturbances and renal lipotoxicity.

Malondialdehyde-modified LDL-related variables are associated with diabetic kidney disease in type 2 diabetes

BACKGROUND AND AIMS

Oxidized low-density lipoprotein (oxLDL) causes the development of atherosclerosis and kidney injury. Although circulating oxLDL levels were reportedly increased in type 2 diabetic patients with macroalbuminuria, it remains unclear whether albuminuria or the reduced glomerular filtration rate (GFR) is independently associated with the circulating oxLDL level. This study aimed to elucidate the association between the stage of diabetic nephropathy and serum malondialdehyde-modified LDL (MDA-LDL) and the ratio of MDA-LDL to LDL-cholesterol (MDA-LDL/LDL).

METHODS AND RESULTS

This retroactive cross-sectional study used data from 402 patients with type 2 diabetes. Patients undergoing hemodialysis were excluded. Serum MDA-LDL levels were significantly increased with increases in severity of albuminuria (103 ± 44 U/L, 109 ± 54 U/L, and 135 ± 72 U/L for normoalbuminuria, microalbuminuria, and macroalbuminuria, respectively; P for trend = 0.020) but not according to the estimated GFR (eGFR). An increased MDA-LDL/LDL ratio was significantly associated with both increased albuminuria (35 ± 13, 37 ± 14, and 40 ± 15 for normoalbuminuria, microalbuminuria, and macroalbuminuria, respectively; P for trend = 0.003) and reduced eGFR (34 ± 13, 36 ± 13, 38 ± 12, and 51 ± 28 for grade 1, 2, 3 and 4, respectively; P for trend = 0.002). Multiple linear regression analysis showed that neither the albumin excretion rate nor eGFR but ln-transformed triglycerides and LDL-C levels were independent determinants of both serum MDA-LDL levels and MDA-LDL/LDL ratios.

CONCLUSION

Serum MDA-LDL levels and MDA-LDL/LDL ratios were increased in those with dyslipidemia associated with diabetic kidney disease.

Inflammation-activated CXCL16 pathway contributes to tubulointerstitial injury in mouse diabetic nephropathy

Inflammation and lipid disorders play crucial roles in synergistically accelerating the progression of diabetic nephropathy (DN). In this study we investigated how inflammation and lipid disorders caused tubulointerstitial injury in DN in vivo and in vitro. Diabetic db/db mice were injected with 10% casein (0.5 mL, sc) every other day for 8 weeks to cause chronic inflammation. Compared with db/db mice, casein-injected db/db mice showed exacerbated tubulointerstitial injury, evidenced by increased secretion of extracellular matrix (ECM) and cholesterol accumulation in tubulointerstitium, which was accompanied by activation of the CXC chemokine ligand 16 (CXCL16) pathway. In the in vitro study, we treated HK-2 cells with IL-1β (5 ng/mL) and high glucose (30 mmol/L). IL-1β treatment increased cholesterol accumulation in HK-2 cells, leading to greatly increased ROS production, ECM protein expression levels, which was accompanied by the upregulated expression levels of proteins in the CXCL16 pathway. In contrast, after CXCL16 in HK-2 cells was knocked down by siRNA, the IL-1β-deteriorated changes were attenuated. In conclusion, inflammation accelerates renal tubulointerstitial lesions in mouse DN via increasing the activity of CXCL16 pathway.