The possible role of the ubiquitin proteasome system in the development of atherosclerosis in diabetes

Degradation meets development: Implications in β-cell development and diabetes

Pancreatic development is orchestrated by timely synthesis and degradation of stage-specific transcription factors (TFs). The transition from one stage to another stage is dependent on the precise expression of the developmentally relevant TFs. Persistent expression of particular TF would impede the exit from the progenitor stage to the matured cell type. Intracellular protein degradation-mediated protein turnover contributes to a major extent to the turnover of these TFs and thereby dictates the development of different tissues. Since even subtle changes in the crucial cellular pathways would dramatically impact pancreatic β-cell performance, it is generally acknowledged that the biological activity of these pathways is tightly regulated by protein synthesis and degradation process. Intracellular protein degradation is executed majorly by the ubiquitin proteasome system (UPS) and Lysosomal degradation pathway. As more than 90% of the TFs are targeted to proteasomal degradation, this review aims to examine the crucial role of UPS in normal pancreatic β-cell development and how dysfunction of these pathways manifests in metabolic syndromes such as diabetes. Such understanding would facilitate designing a faithful approach to obtain a therapeutic quality of β-cells from stem cells.

Small molecules as modulators of the proteostasis machinery: Implication in cardiovascular diseases

With the escalating prevalence of cardiovascular diseases, the substantial socioeconomic burden on healthcare systems is intensifying. Accumulating empirical evidence underscores the pivotal role of the proteostasis network in regulating cardiac homeostasis and function. Disruptions in proteostasis may contribute to the loss of protein function or the acquisition of toxic functions, which are intricately linked to the development of cardiovascular ailments such as atrial fibrillation, heart failure, atherosclerosis, and cardiac aging. It is widely acknowledged that the proteostasis network encompasses molecular chaperones, autophagy, and the ubiquitin proteasome system (UPS). Consequently, the proteostasis network emerges as an appealing target for therapeutic interventions in cardiovascular diseases. Numerous small molecules, acting as modulators of the proteostasis machinery, have exhibited therapeutic efficacy in managing cardiovascular diseases. This review centers on elucidating the role of the proteostasis network in various cardiovascular diseases and explores the potential of small molecules as therapeutic agents.

Ubiquitin-specific protease 34 in macrophages limits CD8 T cell-mediated onset of vitiligo in mice

As an autoimmune disorder, vitiligo is characterized by depigmented skin macules. CD8⁺T cells and macrophages enrichment promote the onset of vitiligo, while the role of macrophages to CD8⁺T is not well deciphered. To develop a mouse model of vitiligo with prominent epidermal depigmentation, Krt14-Kitl* transgenic mice containing an elevated number of melanocytes in the epidermis with membrane-bound Kit ligand (Kitl*) were adoptively transferred with premelanosome protein (PMEL) CD8⁺ T cells. On the other hand, Krt14-Kitl* mice were mated with ubiquitin-specific protease 34 (USP34)^MKO mice to decipher the role of USP34 in vitiligo. Vitiligo scores and PMEL CD8⁺ T cell enrichment were detected with flow cytometry. Human peripheral blood mononuclear cells (PBMCs) or mice bone marrow-derived macrophages (BMDMs) were incubated with lipopolysaccharide (LPS), CpG, or co-incubated with KU-55933, an ataxia telangiectasia-mutated (ATM) inhibitor. Chemokine (C-C motif) ligand 2 (CCL2), Ccl5, and interleukin (Il)-12α expression was assayed with real-time PCR, and p-IKKα/β was assayed with Western blots. USP34 was up-regulated in the PBMCs of vitiligo patients and LPS-stimulated BMDMs. USP34 deficiency did not affect the differentiation of CD11b⁺F4/80⁺ macrophages in the bone marrow. Immunoprecipitation demonstrated the interaction between USP34 and ATM. USP34 deficiency or KU-55933 administration promoted the induction of Ccl2, Ccl5, Il12α, and p-IKKα/β in LPS or CpG stimulated BMDMs; KU-55933 administration could not affect the expression of the above molecules in USP34 deficient BMDMs. It further revealed that USP34 deficiency promoted the development of vitiligo with increased PMEL CD8⁺ T cell enrichment, which was not affected by KU-55933 administration. USP34 deficiency in macrophages promotes the onset of vitiligo with increased PMEL CD8⁺ T cell enrichment, and USP34/ATM complex can be considered as a therapy target.

RUNX1 and CCL3 in Diabetes Mellitus-Related Coronary Artery Disease: A Bioinformatics Analysis

Background

Cardiovascular complications are a major cause of death and disability in patients with diabetes mellitus, but how such complications arise is unclear.

Methods

Weighted gene correlation network analysis (WGCNA) was performed on gene expression profiles from healthy controls, individuals with diabetes mellitus, and individuals with diabetes mellitus-associated coronary artery disease (DMCAD). Phenotypically related module genes were analyzed for enrichment in Gene Ontology (GO) terms and Kyoto Gene and Genome Encyclopedia (KEGG) pathways. Predicted biological functions were validated using gene set enrichment analysis (GSEA) and ClueGo analysis. Based on the TRRUST v2 database and hypergeometric tests, a global network was built to identify transcription factors (TFs) and downstream target genes potentially involved in DMCAD.

Results

WGCNA identified three modules associated with progression from diabetes mellitus to DMCAD. The module genes were significantly involved in biological processes related to interferon and viral infection, while GSEA of DMCAD samples suggested involvement in viral myocarditis, chemokine signaling and phagosomes. RUNX1 was identified as a potential TF regulating these module genes. Analysis of the global regulatory network of TFs and their targets suggested that CCL3 may be a key regulator in DMCAD.

Conclusion

We found bioinformatic evidence that CCL3 may be a key regulator and RUNX1 a key TF in DMCAD.

Novel therapies for immune thrombocytopenia

Current therapies for immune thrombocytopenia (ITP) are successful in providing a haemostatic platelet count in over two-thirds of patients. Still, some patients have an inadequate response and there is a need for other therapies. A number of novel therapies for ITP are currently being developed based upon the current pathophysiology of ITP. Many therapies are targetted at reducing platelet destruction by decreasing anti-platelet antibody production by immunosuppression with monoclonal antibodies targetted against CD40, CD38 and the immunoproteasome or physically reducing the anti-platelet antibody concentration by inhibition of the neonatal Fc receptor. Others target the phagocytic system by inhibiting FcγR function with staphylococcal protein A, hypersialylated IgG, polymeric Fc fragments, or Bruton kinase. With a recognition that platelet destruction is also mediated by complement, inhibitors of C1s are also being tested. Inhibition of platelet desialylation may also play a role. Other novel therapies promote platelet production with new oral thrombopoietin receptor agonists or the use of low-level laser light to improve mitochondrial activity and prevent megakaryocyte apoptosis. This review will focus on these novel mechanisms for treating ITP and assess the status of treatments currently under development. Successful new treatments for ITP might also provide a pathway to treat other autoimmune disorders.

Prognostic role of hypothyroidism and low free-triiodothyronine levels in patients hospitalized with acute heart failure

Low thyroid function has been widely recognized as a potential cause of heart failure (HF), but the evidence about a possible association with in-hospital, all-cause mortality in patients with acute HF (AHF) is not consistent. This study sought to investigate the prevalence and prognostic role of hypothyroidism, overt and subclinical, and of low free-triiodothyronine (fT3) levels in patients hospitalized with AHF. We retrospectively analyzed consecutive 1018 patients who were hospitalized for AHF in a single academic medical center [Fondazione Policlinico A.Gemelli IRCCS, Rome, Italy] between January 1st 2016, and December 31st 2018. Patients were divided into three groups: normal thyroid function (n = 798), subclinical hypothyroidism (n = 105), and overt hypothyroidism (n = 115). The outcome was in-hospital, all-cause mortality. Patients were 81 years of age, 55% were females and nearly two-thirds of the patients were on New York Heart Association functional class III. The three most common cardiovascular comorbidities were coronary artery disease, hypertension, and atrial fibrillation with no differences across the three groups. Overall, 138 patients (14%) died during the hospital stay. The mortality rate was 27% among patients with overt hypothyroid, 17% among those with subclinical hypothyroidism, and 11% among euthyroid patients (p < 0.001). At a multivariate Cox regression model, overt hypothyroidism (HR 2.1, 95% CI 1.4-3.2) and fT3 levels < 1.8 pg/mL (HR 3.4, 95% CI 2.3-5.1) were associated with an increased likelihood of in-hospital death. No association was found with subclinical hypothyroidism. Among patients hospitalized with AHF, overt hypothyroidism and low fT3 levels are independent predictors of all-cause mortality during the hospital stay.

Hyperinsulinemia and Its Pivotal Role in Aging, Obesity, Type 2 Diabetes, Cardiovascular Disease and Cancer

For many years, the dogma has been that insulin resistance precedes the development of hyperinsulinemia. However, recent data suggest a reverse order and place hyperinsulinemia mechanistically upstream of insulin resistance. Genetic background, consumption of the “modern” Western diet and over-nutrition may increase insulin secretion, decrease insulin pulses and/or reduce hepatic insulin clearance, thereby causing hyperinsulinemia. Hyperinsulinemia disturbs the balance of the insulin–GH–IGF axis and shifts the insulin : GH ratio towards insulin and away from GH. This insulin–GH shift promotes energy storage and lipid synthesis and hinders lipid breakdown, resulting in obesity due to higher fat accumulation and lower energy expenditure. Hyperinsulinemia is an important etiological factor in the development of metabolic syndrome, type 2 diabetes, cardiovascular disease, cancer and premature mortality. It has been further hypothesized that nutritionally driven insulin exposure controls the rate of mammalian aging. Interventions that normalize/reduce plasma insulin concentrations might play a key role in the prevention and treatment of age-related decline, obesity, type 2 diabetes, cardiovascular disease and cancer. Caloric restriction, increasing hepatic insulin clearance and maximizing insulin sensitivity are at present the three main strategies available for managing hyperinsulinemia. This may slow down age-related physiological decline and prevent age-related diseases. Drugs that reduce insulin (hyper) secretion, normalize pulsatile insulin secretion and/or increase hepatic insulin clearance may also have the potential to prevent or delay the progression of hyperinsulinemia-mediated diseases. Future research should focus on new strategies to minimize hyperinsulinemia at an early stage, aiming at successfully preventing and treating hyperinsulinemia-mediated diseases.

The Diabetic Cardiomyopathy: The Contributing Pathophysiological Mechanisms

Individuals with diabetes mellitus (DM) disclose a higher incidence and a poorer prognosis of heart failure (HF) than non-diabetic people, even in the absence of other HF risk factors. The adverse impact of diabetes on HF likely reflects an underlying “diabetic cardiomyopathy” (DM–CMP), which may by exacerbated by left ventricular hypertrophy and coronary artery disease (CAD). The pathogenesis of DM-CMP has been a hot topic of research since its first description and is still under active investigation, as a complex interplay among multiple mechanisms may play a role at systemic, myocardial, and cellular/molecular levels. Among these, metabolic abnormalities such as lipotoxicity and glucotoxicity, mitochondrial damage and dysfunction, oxidative stress, abnormal calcium signaling, inflammation, epigenetic factors, and others. These disturbances predispose the diabetic heart to extracellular remodeling and hypertrophy, thus leading to left ventricular diastolic and systolic dysfunction. This Review aims to outline the major pathophysiological changes and the underlying mechanisms leading to myocardial remodeling and cardiac functional derangement in DM-CMP.

Association Between Morning Surge in Systolic Blood Pressure and SYNTAX Score I in Patients With Stable Coronary Artery Disease

A high morning surge in systolic blood pressure poses a risk in people who have cardiovascular disease. We investigated the relationship between this phenomenon and the SYNTAX score I in patients who had stable coronary artery disease. Our single-center study included 125 consecutive patients (109 men and 16 women; mean age, 54.3 ± 9 yr) in whom coronary angiography revealed stable coronary artery disease. We calculated each patient's sleep-trough morning surge in systolic blood pressure, then calculated the SYNTAX score I. The morning surge was significantly higher in patients whose score was >22 (mean, 22.7 ± 13.2) than in those whose score was ≤22 (mean, 12.4 ± 7.5) (P <0.001). Forward stepwise logistic regression analysis revealed that morning surge in systolic blood pressure was the only independent predictor of an intermediate-to-high score (odds ratio=1.183; 95% CI, 1.025-1.364; P=0.021). To our knowledge, this is the first study to show an association between morning surge in systolic blood pressure and the SYNTAX score I in patients who have stable coronary artery disease.

Impact of SGLT2 Inhibitors on Heart Failure: From Pathophysiology to Clinical Effects

Heart failure (HF) affects up to over 20% of patients with type 2 diabetes (T2DM), even more in the elderly. Although, in T2DM, both hyperglycemia and the proinflammatory status induced by insulin resistance are crucial in cardiac function impairment, SGLT2i cardioprotective mechanisms against HF are several. In particular, these beneficial effects seem attributable to the significant reduction of intracellular sodium levels, well-known to exert a cardioprotective role in the prevention of oxidative stress and consequent cardiomyocyte death. From a molecular perspective, patients’ exposure to gliflozins’ treatment mimics nutrient and oxygen deprivation, with consequent autophagy stimulation. This allows to maintain the cellular homeostasis through different degradative pathways. Thus, since their introduction in the clinical practice, the hypotheses on SGLT2i mechanisms of action have changed: from simple glycosuric drugs, with consequent glucose lowering, erythropoiesis enhancing and ketogenesis stimulating, to intracellular sodium-lowering molecules. This provides their consequent cardioprotective effect, which justifies its significant reduction in CV events, especially in populations at higher risk. Finally, the updated clinical evidence of SGLT2i benefits on HF was summarized. Thus, this review aimed to analyze the cardioprotective mechanisms of sodium glucose transporter 2 inhibitors (SGLT2i) in patients with HF, as well as their clinical impact on cardiovascular events.

Severe, but not mild to moderate, non-alcoholic fatty liver disease associated with increased risk of subclinical coronary atherosclerosis

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is associated with high risk of cardiovascular disease. The prevalence is increasing to 45-65% in the general population with routine health check-up, and most subjects have the mild degree NAFLD in recent years. Moreover, there are no studies on the association between NAFLD severity and coronary atherosclerosis in the real-world setting by ultrasonography.

METHODS

The aim of this study was to determine the relationship between the severity of NAFLD and subclinical coronary atherosclerosis. Overall, 817 subjects meet criteria for NAFLD were enrolled in the retrospective cohort study (155 subjects were excluded). The severity of NAFLD was divided into the normal, mild, moderate and severe degree based on the finding of abdominal ultrasonography. The assessment of coronary atherosclerosis was based on CAC scan/coronary CT angiography finding in terms of CAC score ≧ 100, CAC score ≧ 400, CAD-RADS ≧ 3 and presence of vulnerable plaque(s).

RESULTS

A significant linear trend was observed between the severity of NAFLD and subclinical coronary atherosclerosis. Compared with the reference group (including normal, mild, and moderate NAFLD), severe degree NAFLD was the independently associated risk of subclinical coronary atherosclerosis in term of CAC score ≧ 100, CAC score ≧ 400, CAD-RADS ≧ 3 and presence of vulnerable plaque(s) based on binary logistic regression after adjustment for FRS score and body fat percentage.

CONCLUSIONS

Severe degree, but not mild to moderate, was associated with high risk of subclinical coronary atherosclerosis, independently of FRS score and body-fat percentage.

HDL Improves Cholesterol and Glucose Homeostasis and Reduces Atherosclerosis in Diabetes-Associated Atherosclerosis

BACKGROUND AND AIMS

Apolipoprotein A-I (ApoA-I), the main component of high-density lipoprotein (HDL), not only promotes reverse cholesterol transport (RCT) in atherosclerosis but also increases insulin secretion in pancreatic β-cells, suggesting that interventions which raise HDL levels may be beneficial in diabetes-associated cardiovascular disease (CVD). Previously, we showed that TNF-related apoptosis-inducing ligand (TRAIL) deletion in Apolipoprotein Eknockout (Apoe-/- ) mice results in diabetes-accelerated atherosclerosis in response to a "Western" diet. Here, we sought to identify whether reconstituted HDL (rHDL) could improve features of diabetes-associated CVD in Trail-/-Apoe-/- mice.

METHODS AND RESULTS

Trail-/-Apoe-/- and Apoe-/- mice on a "Western" diet for 12 weeks received 3 weekly infusions of either PBS (vehicle) or rHDL (containing ApoA-I (20 mg/kg) and 1-palmitoyl-2-linoleoyl phosphatidylcholine). Administration of rHDL reduced total plasma cholesterol, triglyceride, and glucose levels in Trail-/-Apoe-/- but not in Apoe-/- mice, with no change in weight gain observed. rHDL treatment also improved glucose clearance in response to insulin and glucose tolerance tests. Immunohistological analysis of pancreata revealed increased insulin expression/production and a reduction in macrophage infiltration in mice with TRAIL deletion. Furthermore, atherosclerotic plaque size in Trail-/-Apoe-/- mice was significantly reduced associating with increased expression of the M2 macrophage marker CD206, suggesting HDL's involvement in the polarization of macrophages. rHDL also increased vascular mRNA expression of RCT transporters, ABCA1 and ABCG1, in Trail-/-Apoe-/- but not in Apoe-/- mice. Conclusions. rHDL improves features of diabetes-associated atherosclerosis in mice. These findings support the therapeutic potential of rHDL in the treatment of atherosclerosis and associated diabetic complications. More studies are warranted to understand rHDL's mechanism of action.

Proliferative diabetic retinopathy in patients with type 2 diabetes correlates with the presence of atherosclerosis cardiovascular disease

BACKGROUND

Atherosclerosis cardiovascular disease (ASCVD) is the main cause of morbidity and mortality in type 2 diabetes mellitus (T2DM). As most diabetic patients with ASCVD are asymptomatic, it is most neglected in clinical practice. For this reason, identifying high-risk ASCVD population with intensified treatment is very important. In recent years, the relationship between diabetic retinopathy (DR) and ASCVD has caused much academic concern, but the results are inconsistent. Moreover, whether all grades of DR increase the risk of ASCVD remains controversial. Most importantly, very few data can be found in China.

OBJECTIVE

Our aim is to discuss whether all grades of DR increase the risk of ASCVD after adjustment for the traditional cardiovascular risk factors and to assess the independent contribution of DR to cardiovascular events in patients with T2DM, hoping to provide more evidence for early identification of ASCVD.

RESEARCH DESIGN AND METHODS

A total of 425 T2DM patients with complete physical and biochemical data were included in the study. The grade of DR was assessed with two 45 color digital retinal images. Based on the presence of history of ASCVD, 425 T2DM patients were divided into 2 groups: ASCVD group and non-ASCVD group.

RESULTS

ASCVD patients were older and had a significantly higher fasting plasma glucose (FPG) and glycated haemoglobin (HbA1c) and proportion of history of ASCVD. At the same time, they were more likely to be females, and had lower level of alcohol and calculated glomerular filtration rate (eGFR) than non-ASCVD patients. Their trend to develop DR with ASCVD was significantly higher than patients with non-ASCVD (χ² = 5.805, P  = 0.016). DR was an independent statistical indicator of the presence of ASCVD [odds ratio (OR) (95% CI): 2.321 (1.152-4.678), P = 0.018]. Furthermore, when DR was divided into non-proliferative retinopathy (NPDR) and proliferative retinopathy (PDR) according to its severity, only PDR was significantly associated with incident ASCVD [OR (95% CI): 8.333 (1.813-38.304), P = 0.006]. After adjusting for traditional ASCVD risk factors, such an association still existed [OR (95% CI): 7.466 (1.355-41.137), P = 0.021].

CONCLUSION

DR associates strongly with ASCVD in the Chinese population with T2DM. With the increasing severity of DR, the risk of ASCVD also increases. After adjustment for traditional risk factors, PDR is still an independent risk marker for ASCVD.

The association of baseline N-terminal pro-B-type natriuretic peptide with short and long-term prognosis following percutaneous coronary intervention in non-ST segment elevation acute coronary syndrome with multivessel coronary artery disease: a retrospective cohort study

BACKGROUND

Several studies have shown that N-terminal pro-B-type natriuretic peptide (NT-proBNP) is strongly correlated with the complexity of coronary artery disease and the prognosis of patients with non-ST segment elevation acute coronary syndrome (NSTE-ACS), However, it remains unclear about the prognostic value of NT-proBNP in patients with NSTE-ACS and multivessel coronary artery disease (MCAD) undergoing percutaneous coronary intervention (PCI). Therefore, this study aimed to reveal the relationship between NT-proBNP levels and the prognosis for NSTE-ACS patients with MCAD undergoing successful PCI.

METHODS

This study enrolled 1022 consecutive NSTE-ACS patients with MCAD from January 2010 to December 2014. The information of NT-proBNP levels was available from these patients. The primary outcome was in-hospital all-cause death. In addition, the 3-year follow-up all-cause death was also ascertained.

RESULTS

A total of 12 (1.2%) deaths were reported during hospitalization. The 4th quartile group of NT-proBNP (> 1287 pg/ml) showed the highest in-hospital all-cause death rate (4.3%) (P < 0.001). Besides, logistic analyses revealed that the increasing NT-proBNP level was robustly associated with an increased risk of in-hospital all-cause death (adjusted odds ratio (OR): 2.86, 95% confidence interval (CI) = 1.16-7.03, P = 0.022). NT-proBNP was able to predict the in-hospital all-cause death (area under the curve (AUC) = 0.888, 95% CI = 0.834-0.941, P < 0.001; cutoff: 1568 pg/ml). Moreover, as revealed by cumulative event analyses, a higher NT-proBNP level was significantly related to a higher long-term all-cause death rate compared with a lower NT-proBNP level (P < 0.0001).

CONCLUSIONS

The increasing NT-proBNP level is significantly associated with the increased risks of in-hospital and long-term all-cause deaths among NSTE-ACS patients with MCAD undergoing PCI. Typically, NT-proBN P > 1568 pg/ml is related to the all-cause and in-hospital deaths.

SCD leads to the development and progression of acute myocardial infarction through the AMPK signaling pathway

Background

Acute myocardial infarction (AMI) is myocardial necrosis caused by acute coronary ischemia and hypoxia. It can be complicated by arrhythmia, shock, heart failure and other symptoms that can be life-threatening. A multi-regulator driven dysfunction module for AMI was constructed. It is intended to explore the pathogenesis and functional pathways regulation of acute myocardial infarction.

Methods

Combining differential expression analysis, co-expression analysis, and the functional enrichment analysis, a set of expression disorder modules related to AMI was obtained. Hypergeometric test was performed to calculate the potential regulatory effects of multiple factors on the module, identifying a range of non-coding RNA and transcription factors.

Results

A total of 4551 differentially expressed genes for AMI and seven co-expression modules were obtained. These modules are primarily involved in the metabolic processes of prostaglandin transport processes, regulating DNA recombination and AMPK signal transduction. Based on this set of functional modules, 3 of 24 transcription factors (TFs) including NFKB1, MECP2 and SIRT1, and 3 of 782 non-coding RNA including miR-519D-3P, TUG1 and miR-93-5p were obtained. These core regulators are thought to be involved in the progression of AMI disease. Through the AMPK signal transduction, the critical gene stearoyl-CoA desaturase (SCD) can lead to the occurrence and development of AMI.

Conclusions

In this study, a dysfunction module was used to explore the pathogenesis of multifactorial mediated AMI and provided new methods and ideas for subsequent research. It helps researchers to have a deeper understanding of its potential pathogenesis. The conclusion provides a theoretical basis for biologists to design further experiments related to AMI.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02011-8.

Low 25-hydroxyvitamin D is associated with arterial stiffness in Chinese with Type 2 diabetes mellitus

OBJECTIVES

Arterial stiffness (AS), one of the complications of diabetes, associated with many metabolic factors. This study aimed to investigate the association between 25-hydroxyvitamin D(25(OH)D) and AS in type 2 diabetes mellitus (T2DM).

METHODS

We identified 1335 diabetic patients from the Department of Endocrinology, Shanghai Tenth People's Hospital. Finally, 603 T2DM patients were included in the study. They were divided into two groups: AS group (baPWV ≥ 15,500 cm/s) and the control group (baPWV < 1550 cm/s).

RESULTS

(1) Heart rate (HR) and systolic pressure (SBP) were higher while body weight and body mass index (BMI) were smaller in AS group than the control group (all P < 0.05). (2) Compared to patients without AS, patients with AS showed lower 25(OH)D and higher rate of 25(OH)D deficiency (42 ± 16 vs. 45 ± 17 mol/l, 68% vs. 64%, all P < 0.05). (3) BaPWV was negatively associated with 25(OH)D (r = -0.12, P = 0.004), while positively associated with age, duration of diabetes, HR, SBP, and low-density lipoprotein cholesterol and negatively associated with body weight and BMI (all P < 0.05). (4) Multiple linear regression showed that 25(OH)D was the negatively influencing factor of baPWV (β = -2.2, P = 0.01). Logistic regression showed that age and SBP were risk factor of AS (OR:1.07, 95% CI: 1.05-1.10, P < 0.001; OR:1.03, 95% CI: 1.02-1.04, P < 0.001) while 25(OH)D was protective factor of AS (OR:0.987, 95% CI: 0.976-0.998, P = 0.024).

CONCLUSIONS

T2DM patients with AS had lower 25(OH)D and higher rate of 25(OH)D deficiency. There was a negative relationship between 25(OH)D and AS assessed by baPWV.

A novel numerical model of combination levels of C-peptide and insulin in coronary artery disease risk prediction

OBJECTIVE

Insulin resistance is a major risk factor for coronary artery disease (CAD). The C-peptide-to-insulin ratio (C/I) is associated with hepatic insulin clearance and insulin resistance. The current study was designed to establish a novel C/I index (CPIRI) model and provide early risk assessment of CAD.

METHODS

A total of 865 adults diagnosed with new-onset diabetes mellitus (DM) within one year and 54 healthy controls (HC) were recruited to develop a CPIRI model. The CPIRI model was established with fasting C/I as the independent variable and homeostasis model assessment of insulin resistance (HOMA-IR) as the dependent variable. Associations between the CPIRI model and the severity of CAD events were also assessed in 45 hyperglycemic patients with CAD documented via coronary arteriography (CAG) and whom underwent stress echocardiography (SE) and exercise electrocardiography test (EET).

RESULTS

Fasting C-peptide/insulin and HOMA-IR were hyperbolically correlated in DM patients and HC, and log(C/I) and log(HOMA-IR) were linearly and negatively correlated. The respective correlational coefficients were -0.83 (p < 0.001) and -0.76 (p < 0.001). The equations CPIRI(DM) = 670/(C/I)2.24 + 0.25 and CPIRI(HC) = 670/(C/I)2.24 - 1 (F = 1904.39, p < 0.001) were obtained. Patients with insulin resistance exhibited severe coronary artery impairment and myocardial ischemia. In CAD patients there was no significant correlation between insulin resistance and the number of vessels involved.

CONCLUSIONS

CPIRI can be used to effectively evaluate insulin resistance, and the combination of CPIRI and non-invasive cardiovascular examination is of great clinical value in the assessment of CAD.

Increased co-expression of PSMA2 and GLP-1 receptor in cervical cancer models in type 2 diabetes attenuated by Exendin-4: A translational case-control study

BACKGROUND

Type 2 diabetes (T2D) increases the risk of many types of cancer. Dysregulation of proteasome-related protein degradation leads to tumorigenesis, while Exendin-4, a glucagon-like peptide 1 receptor (GLP-1R) agonist, possesses anti-cancer effects.

METHODS

We explored the co-expression of proteasome alpha 2 subunit (PSMA2) and GLP-1R in the Cancer Genome Atlas (TCGA) database and human cervical cancer specimens, supplemented by in vivo and in vitro studies using multiple cervical cancer cell lines.

FINDINGS

PSMA2 expression was increased in 12 cancer types in TCGA database and cervical cancer specimens from patients with T2D (T2D vs non-T2D: 3.22 (95% confidence interval CI: 1.38, 5.05) vs 1.00 (0.66, 1.34) fold change, P = 0.01). psma2-shRNA decreased cell proliferation in vitro, and tumour volume and Ki67 expression in vivo. Exendin-4 decreased psma2 expression, tumour volume and Ki67 expression in vivo. There was no change in GLP-1R expression in 12 cancer types in TCGA database. However, GLP-1R expression (T2D vs non-T2D: 5.49 (3.0, 8.1) vs 1.00 (0.5, 1.5) fold change, P < 0.001) was increased and positively correlated with PSMA2 expression in T2D-related (r = 0.68)  but not in non-T2D-related cervical cancer specimens. This correlation was corroborated by in vitro experiments where silencing glp-1r decreased psma2 expression. Exendin-4 attenuated phospho-p65 and -IκB expression in the NF-κB pathway.

INTERPRETATION

PSMA2 and GLP-1R expression in T2D-related cervical cancer specimens was increased and positively correlated, suggesting hyperglycaemia might promote cancer growth by increasing PSMA2 expression which could be attenuated by Exendin-4.

FUNDING

This project was supported by Postdoctoral Fellowship Scheme, Direct Grant, Diabetes Research and Education Fund from the Chinese University of Hong Kong (CUHK).

Role of Albuminuria in Detecting Cardio-Renal Risk and Outcome in Diabetic Subjects

The clinical significance of albuminuria in diabetic subjects and the impact of its reduction on the main cardiorenal outcomes by different drug classes are among the most interesting research focuses of recent years. Although nephrologists and cardiologists have been paying attention to the study of proteinuria for years, currently among diabetics, increased urine albumin excretion ascertains the highest cardio-renal risk. In fact, diabetes is a condition by itself associated with a high-risk of both micro/macrovascular complications. Moreover, proteinuria reduction in diabetic subjects by several treatments lowers both renal and cardiovascular disease progression. The 2019 joint ESC-EASD guidelines on diabetes, prediabetes and cardiovascular (CV) disease assign to proteinuria a crucial role in defining CV risk level in the diabetic patient. In fact, proteinuria by itself allows the diabetic patient to be staged at very high CV risk, thus affecting the choice of anti-hyperglycemic drug class. The purpose of this review is to present a clear update on the role of albuminuria as a cardio-renal risk marker, starting from pathophysiological mechanisms in support of this role. Besides this, we will show the prognostic value in observational studies, as well as randomized clinical trials (RCTs) demonstrating the potential improvement of cardio-renal outcomes in diabetic patients by reducing proteinuria.

Mechanisms of Non-Alcoholic Fatty Liver Disease in the Metabolic Syndrome. A Narrative Review

Non-alcoholic fatty liver disease (NAFLD) and metabolic syndrome (MS) are two different entities sharing common clinical and physio-pathological features, with insulin resistance (IR) as the most relevant. Large evidence leads to consider it as a risk factor for cardiovascular disease, regardless of age, sex, smoking habit, cholesterolemia, and other elements of MS. Therapeutic strategies remain still unclear, but lifestyle modifications (diet, physical exercise, and weight loss) determine an improvement in IR, MS, and both clinical and histologic liver picture. NAFLD and IR are bidirectionally correlated and, consequently, the development of pre-diabetes and diabetes is the most direct consequence at the extrahepatic level. In turn, type 2 diabetes is a well-known risk factor for multiorgan damage, including an involvement of cardiovascular system, kidney and peripheral nervous system. The increased MS incidence worldwide, above all due to changes in diet and lifestyle, is associated with an equally significant increase in NAFLD, with a subsequent rise in both morbidity and mortality due to both metabolic, hepatic and cardiovascular diseases. Therefore, the slowdown in the increase of the "bad company" constituted by MS and NAFLD, with all the consequent direct and indirect costs, represents one of the main challenges for the National Health Systems.

Circulating level of microRNA-142-5p is a potential biomarker for predicting in-stent restenosis: a case-control study

Background

Patients who receive percutaneous coronary intervention (PCI) have different chances of developing in-stent restenosis (ISR). To date, no predictable biomarker can be applied in the clinic. MicroRNAs (miRNAs or miRs) play critical roles in transcription regulation, and their circulating levels were reported to have potential as clinical biomarkers.

Methods

In total, 93 coronary stent-implanted patients without pregnancy, liver or renal dysfunction, malignancy, hemophilia, or autoimmune diseases were recruited in this clinical study. All recruited participants were divided into an ISR group (n = 45) and a non-ISR group (n = 48) based on their restenotic status as confirmed by cardiologists at the first follow-up visit (6 months after surgery). Blood samples of all participants were harvested to measure circulating levels of miRNA candidates (miR-132, miR-142-5p, miR-15b, miR-24-2, and miR-424) to evaluate whether these circulating miRNAs can be applied as predictive biomarkers of ISR.

Results

Our data indicated that circulating levels of miR-142-5p were significantly higher in the ISR population, and results from the receiver operating characteristic (ROC) curve analysis also demonstrated superior discriminatory ability of miR-142-5p in predicting patients’ restenotic status. In addition, circulating levels of miR-15b, miR-24-2, and miR-424 had differential expressions in participants with diabetes, hyperlipidemia, and hypertension, respectively.

Conclusions

The current study revealed that the circulating level of miR-142-5p has potential application as a clinical biomarker for predicting the development of ISR in stent-implanted patients.

Dysregulation of serum miR-361-5p serves as a biomarker to predict disease onset and short-term prognosis in acute coronary syndrome patients

Background

Serum microRNAs (miRNAs) have been used as novel biomarkers for various diseases, including acute coronary syndrome (ACS). This study aimed to investigate the expression and clinical significance of microRNA-361-5p (miR-361-5p) in patients with ACS.

Methods

This study included 118 ACS patients, 78 patients with stable coronary heart disease (SCHD) and 66 healthy controls. MiR-361-5p expression was measured by qRT-PCR. The diagnostic value of miR-361-5p was evaluated by the ROC analysis. A 30-day follow-up was performed for the patients from hospitalization, and Kaplan–Meier curves and logistics analysis were used to evaluate the ability of miR-361-5p to predict the occurrence of major adverse cardiac events (MACE). ELISA kits were used to detect the levels of endothelial dysfunction (ED) markers, including vascular cell adhesion molecule 1 (VCAM-1), intercellular adhesion molecule 1 (ICAM-1) and E-selectin.

Results

The expression of miR-361-5p was significantly increased in patients with SCHD and ACS, and positively correlated with Gensini scores. Serum miR-361-5p expression had a high diagnostic accuracy for distinguishing ACS from health controls and SCHD patients. ACS patients with high expression of miR-361-5p had a higher probability of developing MACE. MiR-361-5p expression was an independent risk factor for the occurrence of MACE in ACS patients, and was positively correlated with the levels of VCAM-1, ICAM-1 and E-selectin.

Conclusion

All data indicated that miR-361-5p expression was significantly increased in ACS patients. Aberrant miR-361-5p expression in ACS might be a candidate biomarker for ACS diagnosis and the the prediction of MACE onset.

Non-Alcoholic Fatty Liver Disease: From Pathogenesis to Clinical Impact

Non-Alcoholic Fatty Liver Disease (NAFLD) is caused by the accumulation of fat in over 5% of hepatocytes in the absence of alcohol consumption. NAFLD is considered the hepatic manifestation of metabolic syndrome (MS). Recently, an expert consensus suggested as more appropriate the term MAFLD (metabolic-associated fatty liver disease). Insulin resistance (IR) plays a key role in the development of NAFLD, as it causes an increase in hepatic lipogenesis and an inhibition of adipose tissue lipolysis. Beyond the imbalance of adipokine levels, the increase in the mass of visceral adipose tissue also determines an increase in free fatty acid (FFA) levels. In turn, an excess of FFA is able to determine IR through the inhibition of the post-receptor insulin signal. Adipocytes secrete chemokines, which are able to enroll macrophages inside the adipose tissue, responsible, in turn, for the increased levels of TNF-α. The latter, as well as resistin and other pro-inflammatory cytokines such as IL-6, enhances insulin resistance and correlates with endothelial dysfunction and an increased cardiovascular (CV) risk. In this review, the role of diet, intestinal microbiota, genetic and epigenetic factors, low-degree chronic systemic inflammation, mitochondrial dysfunction, and endoplasmic reticulum stress on NAFLD have been addressed. Finally, the clinical impact of NAFLD on cardiovascular and renal outcomes, and its direct link with type 2 diabetes have been discussed.

FGF-23 correlates with endocrine and metabolism dysregulation, worse cardiac and renal function, inflammation level, stenosis degree, and independently predicts in-stent restenosis risk in coronary heart disease patients underwent drug-eluting-stent PCI

Background

The present study aimed to assess the correlation of fibroblast growth factor (FGF)-23 expression with clinical characteristics, then further explore its value in predicting 2-year in-stent restenosis (ISR) risk in coronary heart disease (CHD) patients underwent percutaneous coronary intervention (PCI) with drug-eluting stent (DES).

Methods

In this prospective, single-center, observational study, totally 214 CHD patients treated by PCI with DES were consecutively recruited, and peripheral blood samples were collected prior to PCI with DES for serum samples isolation. Following, FGF-23 level in the serum samples was detected via enzyme linked-immuno-sorbent Assay. The follow-up coronary angiography was performed at 1 year and 2 years after PCI or if suspected ISR symptoms occurred.

Results

FGF-23 was positively correlated with fasting blood-glucose, insulin resistance, serum creatinine, serum uric acid, LDL-C, high-sensitivity C-reactive protein, cardiac troponin I and N-terminal-proB-type natriuretic peptide, while was negatively associated with HDL-C and left ventricular ejection fraction (all P < 0.01). Furthermore, FGF-23 was positively correlated with hypercholesteremia, hyperuricemia and family history of CAD (all P < 0.05). However, it did not correlate with other chronic complications, biochemical indexes, lesion features or PCI parameters (all P > 0.05). Moreover, FGF-23 level was higher in 2-year ISR patients (n = 38) compared to 2-year non-ISR patients (n = 176) (P < 0.001), and receiver operating characteristic curve indicated that FGF-23 was of good value in predicting 2-year ISR risk (AUC 0.828, 95% CI 0.761–0.896).

Conclusion

FGF-23 correlates with endocrine and metabolism dysregulation, worse cardiac and renal function, inflammation level, stenosis degree of target lesion, and serves as an independent risk factor for 2-year ISR risk in CHD patients underwent PCI with DES.

Body Composition and Metabolic Improvement in Patients Followed Up by a Multidisciplinary Team for Obesity in China

BACKGROUND

This study evaluated the effectiveness of the multidisciplinary team (including a specialist, a dietitian, a physical exercise trainer, a surgeon for bariatric surgery, an acupuncturist, and several health educators) for obesity management and the body composition change and improvements in metabolic biomarkers during a 2-year follow-up.

MATERIALS AND METHODS

A total of 119 patients participated in the multidisciplinary team for obesity. Patients were followed up at 3 months, 6 months, 1 year, 18 months, and 2 years after their first visit. Individuals were divided into the high-protein diet (HPD) and standard-protein diet (SPD) group according to their results on a diet questionnaire that they filled out during follow-up.

RESULTS

After 1.2 years, the mean body weight of the participants dropped from 89.7 kg to 80.9 kg (p < 0.001). The body adiposity index was reduced from 33.9 to 32.0 (p < 0.001), while the fat-free mass index from 17.0 to 15.2 (p = 0.043). Fasting glucose and HbA1c were also lower after treatment (p = 0.002 and 0.038 for FPG and HbA1c, respectively). Fasting insulin and HOMA-IR were reduced (p = 0.002 and <0.001 for fasting insulin and HOMA-IR, respectively). HDL-c increased along with weight loss (1.06 mmol/L vs. 1.19 mmol/L, p < 0.001), and transaminase levels significantly dropped (p = 0.001 and 0.021 for ALT and AST, respectively). During treatment, mean protein intake was 29.9% in the HPD group and 19.5% in the SPD group (p < 0.001). Weight loss, reduction of visceral fat area, maintenance of lean body mass, body adiposity index, and fat-free mass index showed no statistical significance between the HPD and SPD groups, as well as glucose metabolic variables.

CONCLUSIONS

A multidisciplinary team for obesity management could significantly reduce body weight and improve metabolic indicators, including HDL-c, transaminase, and insulin resistance. A high-protein diet does not produce better weight control or body composition compared with a standard calorie-restricted diet.

Can Metformin Exert as an Active Drug on Endothelial Dysfunction in Diabetic Subjects?

Cardiovascular mortality is a major cause of death among in type 2 diabetes (T2DM). Endothelial dysfunction (ED) is a well-known important risk factor for the development of diabetes cardiovascular complications. Therefore, the prevention of diabetic macroangiopathies by preserving endothelial function represents a major therapeutic concern for all National Health Systems. Several complex mechanisms support ED in diabetic patients, frequently cross-talking each other: uncoupling of eNOS with impaired endothelium-dependent vascular response, increased ROS production, mitochondrial dysfunction, activation of polyol pathway, generation of advanced glycation end-products (AGEs), activation of protein kinase C (PKC), endothelial inflammation, endothelial apoptosis and senescence, and dysregulation of microRNAs (miRNAs). Metformin is a milestone in T2DM treatment. To date, according to most recent EASD/ADA guidelines, it still represents the first-choice drug in these patients. Intriguingly, several extraglycemic effects of metformin have been recently observed, among which large preclinical and clinical evidence support metformin’s efficacy against ED in T2DM. Metformin seems effective thanks to its favorable action on all the aforementioned pathophysiological ED mechanisms. AMPK pharmacological activation plays a key role, with metformin inhibiting inflammation and improving ED. Therefore, aim of this review is to assess metformin’s beneficial effects on endothelial dysfunction in T2DM, which could preempt development of atherosclerosis.

Chronic hepatitis C infection induces cardiovascular disease and type 2 diabetes: mechanisms and management

Despite the availability of effective treatments, hepatitis C virus (HCV) still remains a threat to public health. HCV is capable to trigger, behind liver damage, extrahepatic manifestations, including cardiovascular disease and type 2 diabetes (T2DM). A close association has been reported between HCV infection and cardiovascular disease due to imbalances in metabolic pathways and chronic inflammation. HCV through both direct and indirect mechanisms causes a higher incidence of ischemic stroke, acute coronary syndrome, heart failure and peripheral arterial disease. In addition, a higher risk of death from cardiovascular events has been showed in HCV patients. Insulin resistance is a hallmark of HCV infection and represents the link between HCV and T2DM, which is one of the most frequent HCV-associated extrahepatic manifestations. The pathological basis of the increased risk of T2DM in HCV infection is provided by the alterations of the molecular mechanisms of IR induced both by the direct effects of the HCV proteins, and by the indirect effects mediated by chronic inflammation, oxidative stress and hepatic steatosis. T2DM increases the risk of compensated and decompensate cirrhosis and hepatocellular carcinoma as well as increases the risk of cardiovascular disease, lower limb amputation and end stage renal disease. Current evidence suggests that HCV eradication reduces the incidence and mortality of cardiovascular disease and T2DM, further underling the importance of public health strategies for eradication the infection. The aim of this review was to update evidence and management of interaction between HCV, cardiovascular disease, and T2DM in the era of DAA treatment.

Studies of liver tissue identify functional gene regulatory elements associated to gene expression, type 2 diabetes, and other metabolic diseases

BACKGROUND

Genome-wide association studies (GWAS) of diseases and traits have found associations to gene regions but not the functional SNP or the gene mediating the effect. Difference in gene regulatory signals can be detected using chromatin immunoprecipitation and next-gen sequencing (ChIP-seq) of transcription factors or histone modifications by aligning reads to known polymorphisms in individual genomes. The aim was to identify such regulatory elements in the human liver to understand the genetics behind type 2 diabetes and metabolic diseases.

METHODS

The genome of liver tissue was sequenced using 10X Genomics technology to call polymorphic positions. Using ChIP-seq for two histone modifications, H3K4me3 and H3K27ac, and the transcription factor CTCF, and our established bioinformatics pipeline, we detected sites with significant difference in signal between the alleles.

RESULTS

We detected 2329 allele-specific SNPs (AS-SNPs) including 25 associated to GWAS SNPs linked to liver biology, e.g., 4 AS-SNPs at two type 2 diabetes loci. Two hundred ninety-two AS-SNPs were associated to liver gene expression in GTEx, and 134 AS-SNPs were located on 166 candidate functional motifs and most of them in EGR1-binding sites.

CONCLUSIONS

This study provides a valuable collection of candidate liver regulatory elements for further experimental validation.

Proteasome biology and therapeutics in cardiac diseases

The ubiquitin proteasome system (UPS) is the major pathway for intracellular protein degradation in most organs, including the heart. UPS controls many fundamental biological processes such as cell cycle, cell division, immune responses, antigen presentation, apoptosis, and cell signaling. The UPS not only degrades substrates but also regulates activity of gene transcription at the post-transcription level. Emerging evidence suggests that impairment of UPS function is sufficient to cause a number of cardiac diseases, including heart failure, cardiomyopathies, hypertrophy, atrophy, ischemia-reperfusion, and atherosclerosis. Alterations in the expression of UPS components, changes in proteasomal peptidase activities and increased ubiquitinated and oxidized proteins have also been detected in diabetic cardiomyopathy (DCM). However, the pathophysiological role of the UPS in DCM has not been examined. Recently, in vitro and in vivo studies have proven highly valuable in assessing effects of various stressors on the UPS and, in some cases, suggesting a causal link between defective protein clearance and disease phenotypes in different cardiac diseases, including DCM. Translation of these findings to human disease can be greatly strengthened by corroboration of discoveries from experimental model systems using human heart tissue from well-defined patient populations. This review will summarize the general role of the UPS in different cardiac diseases, with major focus on DCM, and on recent advances in therapeutic development.

New insights into oxidative stress and inflammation during diabetes mellitus-accelerated atherosclerosis

Oxidative stress and inflammation interact in the development of diabetic atherosclerosis. Intracellular hyperglycemia promotes production of mitochondrial reactive oxygen species (ROS), increased formation of intracellular advanced glycation end-products, activation of protein kinase C, and increased polyol pathway flux. ROS directly increase the expression of inflammatory and adhesion factors, formation of oxidized-low density lipoprotein, and insulin resistance. They activate the ubiquitin pathway, inhibit the activation of AMP-protein kinase and adiponectin, decrease endothelial nitric oxide synthase activity, all of which accelerate atherosclerosis. Changes in the composition of the gut microbiota and changes in microRNA expression that influence the regulation of target genes that occur in diabetes interact with increased ROS and inflammation to promote atherosclerosis. This review highlights the consequences of the sustained increase of ROS production and inflammation that influence the acceleration of atherosclerosis by diabetes. The potential contributions of changes in the gut microbiota and microRNA expression are discussed.

Implication of CD38 gene in autophagic degradation of collagen I in mouse coronary arterial myocytes

Collagen deposition is a hallmark of atherosclerosis. Although compromised collagen I degradation has been implied in the pathogenesis of atherosclerosis, the molecular mechanisms are still unclear. Thus, we determined the role of CD38, an enzyme involved in cellular calcium modulation and autophagic flux, in the regulation of collagen I degradation in coronary arterial myocytes (CAMs).In primary cultured CAMs from CD38^-/- mice, collagen I protein accumulation but not mRNA abundance was significantly increased compared with cells from CD38^+/+ mice either under control or upon TGF-Beta stimulation. Pharmacological inhibition of the formation of autophagosomes with 3-methyladenine or of autophagolysosomes with a lysosomal functional blocker, bafilomycin A1, induced a similar increase in collagen protein levels, while inhibition of the proteasome by MG132 had no effects on collagen I accumulation. In addition, CD38-deficiency did not change the protein expression of matrix metalloprotein-9 (MMP-9) or tissue inhibitor of metalloproteinase-1 (TIMP-1) in CAMs. Confocal microscopy showed that collagen I deposition was mainly lied within lysosomes or autophagosomes in CD38^-/- or TGF-Beta treated CAMs. Collagen I deposition increased when CAMs lack CD38 expression or if autophagy was blocked, which is associated with impaired autophagic degradation of collagen I. This CD38 regulation of autophagic flux may represent a novel mechanism for extracellular matrix (ECM) plasticity of coronary arteries upon atherogenic stimulation.

Changes in expression of proteasome in rats at different stages of atherosclerosis

It has been suggested that proteasome system has a role in initiation, progression, and complication stages of atherosclerosis. Although there is still controversy, there has been no research that compares the expression of proteasome in tissue and serum at each of these stages. This study aimed to investigated the expression of proteasome at different stages of atherosclerosis using rat model. We measured the expression of aortic proteasome by immunohistochemical analyses and were then analyzed using ImageJ software for percentage of area and integrated density. We used Photoshop version 3.0 to analyze aortic proteasome expression as a comparison. We measured serum proteasome expression by enzyme linked immunosorbents assays. Kruskal-Wallis test was used to compare mean value of percentage of area and serum proteasome. Analysis of variance test was used to compare mean value of integrated density. Correlation test between vascular proteasome expression and serum proteasome expression was made using Spearman test. A P-value of 0.05 was considered statistically significant. Compared with normal, percentage of area was higher in initiation, progression, and complication. Compared with normal, integrated density was higher in initiation and further higher in progression and complication. Data from Image J is similar with data from Photoshop. Serum proteasome expression was higher in initiation compared with normal, and further higher in progression and complication. It was concluded that there were different vascular proteasome expression and serum proteasome expression at the stages of atherosclerosis. These results may be used in research into new marker and therapeutic target in atherosclerosis.

Tyrosine hydroxylase is short-term regulated by the ubiquitin-proteasome system in PC12 cells and hypothalamic and brainstem neurons from spontaneously hypertensive rats: possible implications in hypertension

Aberrations in the ubiquitin-proteasome system (UPS) are implicated in the pathogenesis of various diseases. Tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamines biosynthesis, is involved in hypertension development. In this study we investigated whether UPS regulated TH turnover in PC12 cells and hypothalamic and brainstem neurons from spontaneously hypertensive rats (SHR) and whether this system was impaired in hypertension. PC12 cells were exposed to proteasome or lysosome inhibitors and TH protein level evaluated by Western blot. Lactacystin, a proteasome inhibitor, induced an increase of 86±15% in TH levels after 30 min of incubation, then it started to decrease up to 6 h to reach control levels and finally it rose up to 35.2±8.5% after 24 h. Bafilomycin, a lysosome inhibitor, did not alter TH protein levels during short times, but it increased TH by 92±22% above basal after 6 h treatment. Before degradation proteasome substrates are labeled by conjugation with ubiquitin. Efficacy of proteasome inhibition on TH turnover was evidenced by accumulation of ubiquitinylated TH after 30 min. Further, the inhibition of proteasome increased the quantity of TH phosphorylated at Ser40, which is essential for TH activity, by 2.7±0.3 fold above basal. TH protein level was upregulated in neurons from hypothalami and brainstem of SHR when the proteasome was inhibited during 30 min, supporting that neuronal TH is also short-term regulated by the proteasome. Since the increased TH levels reported in hypertension may result from proteasome dysfunction, we evaluate proteasme activity. Proteasome activity was significantly reduced by 67±4% in hypothalamic and brainstem neurons from SHR while its protein levels did not change. Present findings show that TH is regulated by the UPS. The impairment in proteasome activity observed in SHR neurons may be one of the causes of the increased TH protein levels reported in hypertension.

Melatonin as a proteasome inhibitor. Is there any clinical evidence?

Proteasome inhibitors and melatonin are both intimately involved in the regulation of major signal transduction proteins including p53, cyclin p27, transcription factor NF-κB, apoptotic factors Bax and Bim, caspase 3, caspase 9, anti-apoptotic factor Bcl-2, TRAIL, NRF2 and transcription factor beta-catenin. The fact that these factors are shared targets of the proteasome inhibitor bortezomib and melatonin suggests the working hypothesis that melatonin is a proteasome inhibitor. Supporting this hypothesis is the fact that melatonin shares with bortezomib a selective pro-apoptotic action in cancer cells. Furthermore, both bortezomib and melatonin increase the sensitivity of human glioma cells to TRAIL-induced apoptosis. Direct evidence for melatonin inhibition of the proteasome was recently found in human renal cancer cells. We raise the issue whether melatonin should be investigated in combination with proteasome inhibitors to reduce toxicity, to reduce drug resistance, and to enhance efficacy. This may be particularly valid for hematological malignancies in which proteasome inhibitors have been shown to be useful. Further studies are necessary to determine whether the actions of melatonin on cellular signaling pathways are due to a direct inhibitory effect on the catalytic core of the proteasome, due to an inhibitory action on the regulatory particle of the proteasome, or due to an indirect effect of melatonin on phosphorylation of signal transducing factors.

Impaired proteostasis: role in the pathogenesis of diabetes mellitus

In living organisms, proteins are regularly exposed to 'molecular ageing', which corresponds to a set of non-enzymatic modifications that progressively cause irreversible damage to proteins. This phenomenon is greatly amplified under pathological conditions, such as diabetes mellitus. For their survival and optimal functioning, cells have to maintain protein homeostasis, also called 'proteostasis'. This process acts to maintain a high proportion of functional and undamaged proteins. Different mechanisms are involved in proteostasis, among them degradation systems (the main intracellular proteolytic systems being proteasome and lysosomes), folding systems (including molecular chaperones), and enzymatic mechanisms of protein repair. There is growing evidence that the disruption of proteostasis may constitute a determining event in pathophysiology. The aim of this review is to demonstrate how such a dysregulation may be involved in the pathogenesis of diabetes mellitus and in the onset of its long-term complications.

Involvement of proteasome and macrophages M2 in the protection afforded by telmisartan against the acute myocardial infarction in Zucker diabetic fatty rats with metabolic syndrome

This study investigated the involvement of proteasome and macrophages M2 in the protection afforded by telmisartan against the acute myocardial infarction in Zucker diabetic fatty (ZDF) rats with metabolic syndrome. ZDF rats were treated for three weeks with telmisartan at doses of 7 and 12 mg/kg/day. After treatment, rats were subjected to a 25 min occlusion of the left descending coronary artery followed by 2 h reperfusion (I/R). At the end of the I/R period, biochemical, immunohistochemical, and echocardiographic evaluations were done. Telmisartan treatment (7 mg/kg and 12 mg/kg) reduced the myocardial infarct size, the expression of proteasome subunits 20S and 26S, and the protein ubiquitin within the heart. The compound has led to an increased M2 macrophage phenotype within the cardiac specimens and a modification of the cardiac cytokine and chemokine profile. This was functionally translated in improved cardiac performance as evidenced by echography after 2 h reperfusion. 7 mg/kg/day telmisartan was sufficient to improve the left ventricular ejection fraction LVEF of the rat heart recorded after I/R (e.g., vehicle 38 ± 2.2%; telmisartan 54 ± 2.7%) and was sufficient to improve the diastolic function and the myocardial performance index up to values of 0.6 ± 0.01 measured after I/R.

Coronary endothelial dysfunction and mitochondrial reactive oxygen species in type 2 diabetic mice

Endothelial cell (EC) dysfunction is implicated in cardiovascular diseases, including diabetes. The decrease in nitric oxide (NO) bioavailability is the hallmark of endothelial dysfunction, and it leads to attenuated vascular relaxation and atherosclerosis followed by a decrease in blood flow. In the heart, decreased coronary blood flow is responsible for insufficient oxygen supply to cardiomyocytes and, subsequently, increases the incidence of cardiac ischemia. In this study we investigate whether and how reactive oxygen species (ROS) in mitochondria contribute to coronary endothelial dysfunction in type 2 diabetic (T2D) mice. T2D was induced in mice by a high-fat diet combined with a single injection of low-dose streptozotocin. ACh-induced vascular relaxation was significantly attenuated in coronary arteries (CAs) from T2D mice compared with controls. The pharmacological approach reveals that NO-dependent, but not hyperpolarization- or prostacyclin-dependent, relaxation was decreased in CAs from T2D mice. Attenuated ACh-induced relaxation in CAs from T2D mice was restored toward control level by treatment with mitoTempol (a mitochondria-specific O2(-) scavenger). Coronary ECs isolated from T2D mice exhibited a significant increase in mitochondrial ROS concentration and decrease in SOD2 protein expression compared with coronary ECs isolated from control mice. Furthermore, protein ubiquitination of SOD2 was significantly increased in coronary ECs isolated from T2D mice. These results suggest that augmented SOD2 ubiquitination leads to the increase in mitochondrial ROS concentration in coronary ECs from T2D mice and attenuates coronary vascular relaxation in T2D mice.

Pioglitazone, extract of compound Danshen dripping pill, and quercetin ameliorate diabetic nephropathy in diabetic rats

BACKGROUND

Oxidative stress appears to play a role in the pathogenesis of diabetes mellitus (DM), and disruption of the ubiquitin-proteasome system may underlie these pathological changes. We tested the effect of pioglitazone (PIO), an extract of Danshen dripping pill (DSP), and quercetin (QUE) on the pathogenesis of DM in a rat model.

METHODS

Male Sprague Dawley rats were maintained in a normal control (NC) group or given a modified diet and streptozotocin (STZ) to induce DM. After STZ treatment, rats were given intragastric placebo, PIO, DSP, or QUE for 8 weeks. At the end of the treatment period, serum and urine chemistry, renal hypertrophy, renal histopathology, and renal expression of ubiquitin and nuclear factor (NF)-κB p65 were analyzed.

RESULTS

DM rats had altered body and kidney weight, altered serum and urine chemistry, increased accumulation of glomerular extracellular matrix (ECM), and increased renal expression of ubiquitin and NF-κB p65, indicating successful establishment of our DM model. Treatment with PIO, DSP, or QUE significantly ameliorated these pathological changes, although treated rats still had some symptoms of DM.

CONCLUSION

DM rats have increased expression of ubiquitin and NF-κB p65 in their renal tubules and glomeruli. PIO, DSP, and QUE ameliorated the pathological changes associated with DM and also reduced the renal expression of ubiquitin and NF-κB p65. These agents may provide protection from renal pathology associated with DM due to their anti-oxidant effects.

Protein damage, repair and proteolysis

Proteins are continuously affected by various intrinsic and extrinsic factors. Damaged proteins influence several intracellular pathways and result in different disorders and diseases. Aggregation of damaged proteins depends on the balance between their generation and their reversal or elimination by protein repair systems and degradation, respectively. With regard to protein repair, only few repair mechanisms have been evidenced including the reduction of methionine sulfoxide residues by the methionine sulfoxide reductases, the conversion of isoaspartyl residues to L-aspartate by L-isoaspartate methyl transferase and deglycation by phosphorylation of protein-bound fructosamine by fructosamine-3-kinase. Protein degradation is orchestrated by two major proteolytic systems, namely the lysosome and the proteasome. Alteration of the function for both systems has been involved in all aspects of cellular metabolic networks linked to either normal or pathological processes. Given the importance of protein repair and degradation, great effort has recently been made regarding the modulation of these systems in various physiological conditions such as aging, as well as in diseases. Genetic modulation has produced promising results in the area of protein repair enzymes but there are not yet any identified potent inhibitors, and, to our knowledge, only one activating compound has been reported so far. In contrast, different drugs as well as natural compounds that interfere with proteolysis have been identified and/or developed resulting in homeostatic maintenance and/or the delay of disease progression.

The role of the proteasome in heart disease

Intensive investigations into the pathophysiological significance of the proteasome in the heart did not start until the beginning of the past decade but exciting progress has been made and summarized here as two fronts. First, strong evidence continues to emerge to support a novel hypothesis that proteasome functional insufficiency represents a common pathological phenomenon in a large subset of heart disease, compromises protein quality control in heart muscle cells, and thereby acts as a major pathogenic factor promoting the progression of the subset of heart disease to congestive heart failure. This front is represented by the studies on the ubiquitin-proteasome system (UPS) in cardiac proteinopathy, which have taken advantage of a transgenic mouse model expressing a fluorescence reporter for UPS proteolytic function. Second, pharmacological inhibition of the proteasome has been explored experimentally as a potential therapeutic strategy to intervene on some forms of heart disease, such as pressure-overload cardiac hypertrophy, viral myocarditis, and myocardial ischemic injury. Not only between the two fronts but also within each one, a multitude of inconsistencies and controversies remain to be explained and clarified. At present, the controversy perhaps reflects the sophistication of cardiac proteasomes in terms of the composition, assembly, and regulation, as well as the intricacy and diversity of heart disease in terms of its etiology and pathogenesis. A definitive role of altered proteasome function in the development of various forms of heart disease remains to be established. This article is part of a Special Issue entitled The 26S Proteasome: When degradation is just not enough!

Intracellular molecular effects of insulin resistance in patients with metabolic syndrome

Aim of the study

Patients with metabolic syndrome (MetS) have an increased risk of cardiovascular disease. Data obtained from muscle biopsies have demonstrated altered insulin signaling (IS) in patients with MetS. The IS regulates critical cell functions including molecular-regulated cellular metabolite fluxes, protein and energetic metabolism, cell proliferation and apoptosis with consequent regulation of cell life including endothelial homeostasis and blood coagulation. However, little is known about blood cell IS in MetS patients. The aim of this study was to develop a method to evaluate IS in peripheral lymphocytes to identify altered intracellular molecules in patients with MetS to use as risk biomarkers of vascular thrombosis.

Patients and Methods

We investigated 40 patients with MetS and 20 controls. MetS was defined according to guidelines from the US National Cholesterol Education Program Adult Treatment Panel III. Blood samples were taken from all participants. Total mononuclear cells were isolated from peripheral blood using density gradient centrifugation. IS molecules were evaluated using Western blot analysis followed by computer-assisted densitometer evaluation.

Results

Lymphocytes of MetS patients showed a reduced mTOR expression (the mammalian target of rapamycin) which is a fundamental molecule of IS. Major impairment of IS was confirmed by reduced upstream and downstream mTOR molecules which regulate fundamental cells metabolic functions.

Conclusions

In patients with MetS, we found a reduction of mTOR and other mTOR-related molecules involved in insulin resistance, cell repair, coagulation and vasculogenesis. A reduced expression of mTOR may reflect an increased risk of vascular thrombosis.

Proteasomal degradation of retinoid X receptor alpha reprograms transcriptional activity of PPARgamma in obese mice and humans

Obese patients have chronic, low-grade inflammation that predisposes to type 2 diabetes and results, in part, from dysregulated visceral white adipose tissue (WAT) functions. The specific signaling pathways underlying WAT dysregulation, however, remain unclear. Here we report that the PPARgamma signaling pathway operates differently in the visceral WAT of lean and obese mice. PPARgamma in visceral, but not subcutaneous, WAT from obese mice displayed increased sensitivity to activation by its agonist rosiglitazone. This increased sensitivity correlated with increased expression of the gene encoding the ubiquitin hydrolase/ligase ubiquitin carboxyterminal esterase L1 (UCH-L1) and with increased degradation of the PPARgamma heterodimerization partner retinoid X receptor alpha (RXRalpha), but not RXRbeta, in visceral WAT from obese humans and mice. Interestingly, increased UCH-L1 expression and RXRalpha proteasomal degradation was induced in vitro by conditions mimicking hypoxia, a condition that occurs in obese visceral WAT. Finally, PPARgamma-RXRbeta heterodimers, but not PPARgamma-RXRalpha complexes, were able to efficiently dismiss the transcriptional corepressor silencing mediator for retinoid and thyroid hormone receptors (SMRT) upon agonist binding. Increasing the RXRalpha/RXRbeta ratio resulted in increased PPARgamma responsiveness following agonist stimulation. Thus, the selective proteasomal degradation of RXRalpha initiated by UCH-L1 upregulation modulates the relative affinity of PPARgamma heterodimers for SMRT and their responsiveness to PPARgamma agonists, ultimately activating the PPARgamma-controlled gene network in visceral WAT of obese animals and humans.

KB-R7943 inhibits high glucose-induced endothelial ICAM-1 expression and monocyte-endothelial adhesion

Hyperglycemia is the major cause of diabetic angiopathy. The aim of our study was to evaluate the impact of KB-R7943, an inhibitor of Na+/Ca2+ exchanger (NCX) on cell growth and function of human "diabetic" endothelial cells (EC). Intercellular adhesion molecule-1 (ICAM-1) expression and NCX activity were determined after EC were exposed to high glucose in the absence and presence of KB-R7943. Coincubation of EC with high glucose for 24 h resulted in a significant increase of monocyte-endothelial cell adhesion and the expression of ICAM-1. These effects were abolished by KB-R7943 and KB-R7943 significantly decreased the activation of NCX induced by high glucose. These findings suggested that KB-R7943 may play a role in inhibiting expression of adhesion molecules by inhibiting the reverse activation of NCX.