A Novel Index Using Soluble CD36 Is Associated with the Prevalence of Type 2 Diabetes Mellitus: Comparison Study with Triglyceride-Glucose Index

Oxidative Stress Induced by Lipotoxicity and Renal Hypoxia in Diabetic Kidney Disease and Possible Therapeutic Interventions: Targeting the Lipid Metabolism and Hypoxia

Oxidative stress, a hallmark pathophysiological feature in diabetic kidney disease (DKD), arises from the intricate interplay between pro-oxidants and anti-oxidants. While hyperglycemia has been well established as a key contributor, lipotoxicity emerges as a significant instigator of oxidative stress. Lipotoxicity encompasses the accumulation of lipid intermediates, culminating in cellular dysfunction and cell death. However, the mechanisms underlying lipotoxic kidney injury in DKD still require further investigation. The key role of cell metabolism in the maintenance of cell viability and integrity in the kidney is of paramount importance to maintain proper renal function. Recently, dysfunction in energy metabolism, resulting from an imbalance in oxygen levels in the diabetic condition, may be the primary pathophysiologic pathway driving DKD. Therefore, we aim to shed light on the pivotal role of oxidative stress related to lipotoxicity and renal hypoxia in the initiation and progression of DKD. Multifaceted mechanisms underlying lipotoxicity, including oxidative stress with mitochondrial dysfunction, endoplasmic reticulum stress activated by the unfolded protein response pathway, pro-inflammation, and impaired autophagy, are delineated here. Also, we explore potential therapeutic interventions for DKD, targeting lipotoxicity- and hypoxia-induced oxidative stress. These interventions focus on ameliorating the molecular pathways of lipid accumulation within the kidney and enhancing renal metabolism in the face of lipid overload or ameliorating subsequent oxidative stress. This review highlights the significance of lipotoxicity, renal hypoxia-induced oxidative stress, and its potential for therapeutic intervention in DKD.

Kidney lipid dysmetabolism and lipid droplet accumulation in chronic kidney disease

Chronic kidney disease (CKD) is a global health problem with rising incidence and prevalence. Among several pathogenetic mechanisms responsible for disease progression, lipid accumulation in the kidney parenchyma might drive inflammation and fibrosis, as has been described in fatty liver diseases. Lipids and their metabolites have several important structural and functional roles, as they are constituents of cell and organelle membranes, serve as signalling molecules and are used for energy production. However, although lipids can be stored in lipid droplets to maintain lipid homeostasis, lipid accumulation can become pathogenic. Understanding the mechanisms linking kidney parenchymal lipid accumulation to CKD of metabolic or non-metabolic origin is challenging, owing to the tremendous variety of lipid species and their functional diversity across different parenchymal cells. Nonetheless, multiple research reports have begun to emphasize the effect of dysregulated kidney lipid metabolism in CKD progression. For example, altered cholesterol and fatty acid metabolism contribute to glomerular and tubular cell injury. Newly developed lipid-targeting agents are being tested in clinical trials in CKD, raising expectations for further therapeutic development in this field.

Insulin resistance estimated by estimated glucose disposal rate predicts outcomes in acute ischemic stroke patients

BACKGROUND

Estimated glucose disposal rate (eGDR), a simple and noninvasive measure of insulin resistance, has been proven to be an independent risk factor for first-time stroke and all-cause mortality. In this study, we aimed to investigate the associations between eGDR and the stroke outcome in patients with first-time acute ischemic stroke (AIS).

METHODS

We included first-time AIS patients with available data on eGDR in the China National Stroke Registry III (CNSR-III), and divided the subjects into lower eGDR group (eGDR ≤ 6 mg/kg/min) and higher eGDR group (eGDR > 6 mg/kg/min). The primary outcome was excellent functional outcome (modified Rankin Scale score 0-1) at 3 months. Secondary outcomes included stroke recurrence and favorable functional outcome (modified Rankin Scale score 0-2) at 3 months, and functional outcome and combined vascular event at one year. Univariate and multivariate analyses were performed to evaluate the association between eGDR and outcomes.

RESULTS

A total of 6,271 patients with AIS were included in this study. The median values of eGDR in lower and higher eGDR group were 5.0 mg/kg/min (interquartile range, 4.2-5.6) and 7.6 mg/kg/min (interquartile range, 6.8-9.6), respectively. Patients with higher eGDR were significantly associated with higher incidence of excellent functional outcome (adjusted odds ratio, 1.24; 95% confidence interval, 1.06-1.45; P < 0.01) at 3 months and favorable (adjusted odds ratio, 1.55; 95% confidence interval, 1.24-1.93; P < 0.01) and excellent (adjusted odds ratio, 1.28; 95% confidence interval, 1.08-1.51; P < 0.01) functional outcome at one year. However, there was no significant difference in stroke recurrence between these two groups at 3 months (adjusted odds ratio, 0.81; 95% confidence interval, 0.61-1.06; P = 0.12) and one year (adjusted odds ratio, 0.91; 95% confidence interval, 0.73-1.14; P = 0.41).

CONCLUSION

eGDR is a predictor of functional outcome in patients with AIS, independent of traditional cardiovascular predictors.

Usefulness of SPISE Index for Screening and Detection of Early Stages of Insulin Resistance among Chilean Young Adults

BACKGROUND

As the gold standard test to quantify insulin resistance (IR) involves intravenous insulin loading and repeated blood glucose monitoring, many indexes have been developed for IR assessment for convenience.

OBJECTIVE

The objective of this study was to evaluate the agreement of the Single-Point Insulin Sensitivity Estimator (SPISE) by comparing it with the homeostasis model assessment of insulin resistance (HOMA-IR) in identifying IR.

METHOD

Data came from the ongoing LIMACHE BIRTH COHORT. 1,948 individuals (aged 22-28 years) were studied. We performed an agreement plot called a Bangdiwala's Observer Agreement to evaluate patterns in departures from agreement in ordinal categorical variables.

RESULTS

According to the Bangdiwala-Weighted statistics, we found that the agreement between both indexes was 0.14; this value would be considered a slight agreement. Thus, we found bias in the marginal distributions, and we noticed that the SPISE has a bias toward the central quintiles of the index.

CONCLUSIONS

The identification of IR in young adult individuals by the SPISE index has slight agreement with HOMA-IR. Therefore, caution would be taken when considering SPISE index among young Chilean adults.

The triglyceride-glucose index as an indicator of insulin resistance and cardiometabolic risk in Brazilian adolescents

Objective

To set cutoff points for the triglyceride and glucose index (TyG) as a marker of insulin resistance (IR) for the pediatric population.

Subjects and methods

This was a cross-sectional study with schoolchildren population-based data using data of 377 schoolchildren age 10 to 17 years of both sexes. We studied metabolic variables associated with IR indicators, such as fasting insulin and blood glucose, to calculate the homeostatic model assessment (HOMA-IR), and we studied triglycerides (TG) to determine the TyG index. We obtained TyG cutoff values for IR using the receiver operation characteristic (ROC), with definitions of sensitivity (Sen), specificity (Spe), and area under the ROC curve (AUC), with the HOMA-IR as reference.

Results

The cutoff points of the TyG index for IR in adolescents are 7.94 for both sexes, 7.91 for boys, and 7.94 for girls, indicating moderate discriminatory power. When we also considered anthropometric variables of excess weight [TyG-BMI (body mass index)] and visceral fat [TyG-WC (waist circumference)], these indexes reached AUC values higher than 0.72, enhancing their potential use for a good diagnosis.

Conclusion

TyG has proven to be a useful instrument for identifying IR in adolescent health screening, with high discrimination capacity when added to anthropometric variables, making it a feasible and inexpensive option.

Proteomic analysis of epicardial adipose tissue from heart disease patients with concomitant heart failure with preserved ejection fraction

BACKGROUND

Although epicardial adipose tissue (EAT) is known to be a major contributor to the pathogenesis of heart failure with preserved ejection fraction (HFpEF), the underlying mechanisms remain incompletely understood. This study aimed to compare the proteomic profiles of EAT from HFpEF patients and patients without HF (non-HF) and to explore candidate molecules characteristic of EAT in HFpEF.

METHODS

EAT samples were collected from patients who underwent cardiac surgery. Proteins were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Gene Ontology (GO) enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, and protein-protein interaction network analysis were conducted. The gene expression of one significant differentially expressed protein was examined by quantitative reverse transcription polymerase chain reaction.

RESULTS

A total of 2416 proteins were detected by LC-MS/MS experiments, and expression levels were quantified for 2349 proteins. Among them, 96 proteins (including 71 upregulated proteins and 25 downregulated proteins) were significantly differentially expressed between the HFpEF (n = 5) and non-HF groups (n = 5). GO enrichment and KEGG pathway analyses revealed that these differentially expressed proteins were predominantly involved in HFpEF-related processes, including lipid metabolic disorder, inflammation, and mitochondrial dysfunction.

CONCLUSIONS

The results of this comprehensive analysis of the EAT proteome in HFpEF patients offer new insights into the pathogenesis of HFpEF and potential molecular targets in EAT.

New insights into renal lipid dysmetabolism in diabetic kidney disease

Lipid dysmetabolism is one of the main features of diabetes mellitus and manifests by dyslipidemia as well as the ectopic accumulation of lipids in various tissues and organs, including the kidney. Research suggests that impaired cholesterol metabolism, increased lipid uptake or synthesis, increased fatty acid oxidation, lipid droplet accumulation and an imbalance in biologically active sphingolipids (such as ceramide, ceramide-1-phosphate and sphingosine-1-phosphate) contribute to the development of diabetic kidney disease (DKD). Currently, the literature suggests that both quality and quantity of lipids are associated with DKD and contribute to increased reactive oxygen species production, oxidative stress, inflammation, or cell death. Therefore, control of renal lipid dysmetabolism is a very important therapeutic goal, which needs to be archived. This article will review some of the recent advances leading to a better understanding of the mechanisms of dyslipidemia and the role of particular lipids and sphingolipids in DKD.

The Multifunctionality of CD36 in Diabetes Mellitus and Its Complications-Update in Pathogenesis, Treatment and Monitoring

CD36 is a multiligand receptor contributing to glucose and lipid metabolism, immune response, inflammation, thrombosis, and fibrosis. A wide range of tissue expression includes cells sensitive to metabolic abnormalities associated with metabolic syndrome and diabetes mellitus (DM), such as monocytes and macrophages, epithelial cells, adipocytes, hepatocytes, skeletal and cardiac myocytes, pancreatic β-cells, kidney glomeruli and tubules cells, pericytes and pigment epithelium cells of the retina, and Schwann cells. These features make CD36 an important component of the pathogenesis of DM and its complications, but also a promising target in the treatment of these disorders. The detrimental effects of CD36 signaling are mediated by the uptake of fatty acids and modified lipoproteins, deposition of lipids and their lipotoxicity, alterations in insulin response and the utilization of energy substrates, oxidative stress, inflammation, apoptosis, and fibrosis leading to the progressive, often irreversible organ dysfunction. This review summarizes the extensive knowledge of the contribution of CD36 to DM and its complications, including nephropathy, retinopathy, peripheral neuropathy, and cardiomyopathy.

The Role of CD36 in Type 2 Diabetes Mellitus: β-Cell Dysfunction and Beyond

Impaired β-cell function is the key pathophysiology of type 2 diabetes mellitus, and chronic exposure of nutrient excess could lead to this tragedy. For preserving β-cell function, it is essential to understand the cause and mechanisms about the progression of β-cells failure. Glucotoxicity, lipotoxicity, and glucolipotoxicity have been suggested to be a major cause of β-cell dysfunction for decades, but not yet fully understood. Fatty acid translocase cluster determinant 36 (CD36), which is part of the free fatty acid (FFA) transporter system, has been identified in several tissues such as muscle, liver, and insulin-producing cells. Several studies have reported that induction of CD36 increases uptake of FFA in several cells, suggesting the functional interplay between glucose and FFA in terms of insulin secretion and oxidative metabolism. However, we do not currently know the regulating mechanism and physiological role of CD36 on glucolipotoxicity in pancreatic β-cells. Also, the downstream and upstream targets of CD36 related signaling have not been defined. In the present review, we will focus on the expression and function of CD36 related signaling in the pancreatic β-cells in response to hyperglycemia and hyperlipidemia (ceramide) along with the clinical studies on the association between CD36 and metabolic disorders.