Glycemic variability is associated with vascular calcification by the markers of endoplasmic reticulum stress-related apoptosis, Wnt1, galectin-3 and BMP-2

Prognostic value of the stress-hyperglycaemia ratio in patients with moderate-to-severe coronary artery calcification: Insights from a large cohort study

AIM

To evaluate the relationship between the stress-hyperglycaemia ratio (SHR) and the clinical prognosis of patients with moderate-to-severe coronary artery calcification (MSCAC).

METHODS

We consecutively enrolled 3841 patients with angiography-detected MSCAC. The individuals were categorized into three groups based on SHR tertiles: T1 (SHR ≤ 0.77), T2 (0.77 < SHR ≤ 0.89) and T3 (SHR > 0.89). The SHR value was calculated using the formula SHR = [admission glucose (mmol/L)]/[1.59 × HbA1c (%) - 2.59]. The primary outcomes were major adverse cardiovascular and cerebrovascular events (MACCEs), including all-cause death, non-fatal myocardial infarction and non-fatal stroke.

RESULTS

During a median follow-up of 3.11 years, 241 MACCEs were recorded. Kaplan-Meier survival analysis showed that the SHR T3 group had the highest incidence of MACCEs (P < .001). Moreover, findings from the restricted cubic spline analysis showed a significant and positive association between the SHR and MACCEs. This correlation remained consistent even after considering other variables that could potentially impact the results (Pnon-linear = .794). When comparing SHR T1 with SHR T3, it was found that SHR T3 was significantly associated with an increased risk of the primary outcome (adjusted hazard ratio = 1.50; 95% confidence interval: 1.10-2.03).

CONCLUSIONS

Patients with MSCAC showed a positive correlation between the SHR and MACCE rate over a 3-year follow-up period. The study showed that an SHR value of 0.83 is the key threshold, indicating a poor prognosis. Future large-scale multicentre investigations should be conducted to determine the predictive value of the SHR in patients with MSCAC.

The detrimental role of galectin-3 and endoplasmic reticulum stress in the cardiac consequences of myocardial ischemia in the context of obesity

The association between cardiac fibrosis and galectin-3 was evaluated in patients with acute myocardial infarction (MI). The role of galectin-3 and its association with endoplasmic reticulum (ER) stress activation in the progression of cardiovascular fibrosis was also evaluated in obese-infarcted rats. The inhibitor of galectin-3 activity, modified citrus pectin (MCP; 100 mg/kg/day), and the inhibitor of the ER stress activation, 4-phenylbutyric acid (4-PBA; 500 mg/kg/day), were administered for 4 weeks after MI in obese rats. Overweight-obese patients who suffered a first MI showed higher circulating galectin-3 levels, higher extracellular volume, and LV infarcted size, as well as lower E/e'ratio and LVEF compared with normal-weight patients. A correlation was observed between galectin-3 levels and extracellular volume. Obese-infarcted animals presented cardiac hypertrophy and reduction in LVEF, and E/A ratio as compared with control animals. They also showed an increase in galectin-3 gene expression, as well as cardiac fibrosis and reduced autophagic flux. These alterations were associated with ER stress activation characterized by enhanced cardiac levels of binding immunoglobulin protein, which were correlated with those of galectin-3. Both MCP and 4-PBA not only reduced cardiac fibrosis, oxidative stress, galectin-3 levels, and ER stress activation, but also prevented cardiac functional alterations and ameliorated autophagic flux. These results show the relevant role of galectin-3 in the development of diffuse fibrosis associated with MI in the context of obesity in both the animal model and patients. Galectin-3 in tandem with ER stress activation could modulate different downstream mechanisms, including inflammation, oxidative stress, and autophagy.

Short-term Glycemic Variability and Its Association With Macrovascular and Microvascular Complications in Patients With Diabetes

The introduction of continuous glucose monitoring inaugurated a new era in clinical practice by shifting the characterization of glycemic control from HbA1c to novel metrics. The one that gained widespread attention over the past decades was glycemic variability (GV), which typically refers to peaks and nadirs of blood glucose measured over a given time interval. GV can be dichotomized into two main categories: short-term and long-term. Short-term GV reflects within-day and between-day glycemic oscillations, and its contribution to diabetic complications remains an enigma. In this review, we summarize the available data about short-term GV and its possible association with both microvascular and macrovascular complications, evaluating different pathogenic mechanisms and demonstrating nonpharmaceutical, as well as pharmaceutical, therapeutic interventions.

Effect of glucose variability on the mortality of adults aged 75 years and over during the first year of the COVID-19 pandemic

BACKGROUND

To our knowledge, only one study has examined the association between glucose variability (GV) and mortality in the elderly population with diabetes. GV was assessed by HbA1c, and a J-shaped curve was observed in the relationship between HbA1c thresholds and mortality. No study of GV was conducted during the COVID-19 pandemic and its lockdown. This study aims to evaluate whether GV is an independent predictor of all-cause mortality in patients aged 75 years or older with and without COVID-19 who were followed during the first year of the COVID-19 pandemic and its lockdown measures.

METHODS

This was a retrospective cohort study of 407,492 patients from the AGED-MADRID dataset aged 83.5 (SD 5.8) years; 63.2% were women, and 29.3% had diabetes. GV was measured by the coefficient of variation of fasting plasma glucose (CV-FPG) over 6 years of follow-up (2015-2020). The outcome measure was all-cause mortality in 2020. Four models of logistic regression were performed, from simple (age, sex) to fully adjusted, to assess the effect of CV-FPG on all-cause mortality.

RESULTS

During follow-up, 34,925 patients died (14,999 women and 19,926 men), with an all-cause mortality rate of 822.3 per 10,000 person-years (95% confidence interval (CI), 813.7 to 822.3) (739 per 10,000; 95% CI 728.7 to 739.0 in women and 967.1 per 10,000; 95% CI 951.7 to 967.2 in men). The highest quartile of CV-FPG was significantly more common in the deceased group (40.1% vs. 23.6%; p < 0.001). In the fully adjusted model including dementia (Alzheimer's disease) and basal FPG, the odds ratio for mortality ranged from 1.88 to 2.06 in patients with T2DM and from 2.30 to 2.61 in patients with normoglycaemia, according to different sensitivity analyses.

CONCLUSIONS

GV has clear implications for clinical practice, as its assessment as a risk prediction tool should be included in the routine follow-up of the elderly and in a comprehensive geriatric assessment. Electronic health records can incorporate tools that allow its calculation, and with this information, clinicians will have a broader view of the medium- and long-term prognosis of their patients.

Association between area under the C-peptide curve during an oral glucose tolerance test and diabetic retinopathy in type 2 diabetes patients

AIMS/INTRODUCTION

To evaluate the relative contributions of the area under the C-peptide curve (AUCC ) in diabetic retinopathy (DR) during an oral glucose tolerance test and C-peptide release test in patients with type 2 diabetes.

MATERIALS AND METHODS

We retrospectively analyzed the data of 969 patients. Their general characteristics were retrieved. A series of parameters for assessing pancreatic β-cells function, such as the AUCC for six time periods: 0-60 min (AUCC0-60 ), 0-120 min (AUCC0-120 ), 0-180 min (AUCC0-180 ), 60-120 min (AUCC60-120 ), 60-180 min (AUCC60-180 ) and 120-180 min (AUCC120-180 ); the area under the glucose-time curve for six time periods: 0-60 min (AUCG0-60 ), 0-120 min (AUCG0-120 ), 0-180 min (AUCG0-180 ), 60-120 min (AUCG60-120 ), 60-180 min (AUCG60-180 ) and 120-180 min (AUCG120-180 ) and their related indexes, were calculated through 0-180 min oral glucose tolerance test and C-peptide release test. We used univariate analysis to examine the potential factors affecting DR. Spearman's correlation was used to analyze the correlation between AUCC -related indexes and DR. The logistic regression model was used to investigate AUCC and its related indexes' contribution to incidence DR. A smooth curve fitting model was used to determine the correlation, non-linear relationship, and threshold effect between AUCC and DR.

RESULTS

Of the 969 patients with type 2 diabetes, 469 (48.40%) and 500 (51.60%) were classified as the DR group and non-DR group. Compared with the non-DR group, the DR patients had lower AUCC and AUCC /AUCG . Spearman's correlation analysis showed that AUCC -related indexes were all negatively correlated with DR. The logistic regression analysis determined that there were associations between AUCC and DR in the adjusted models. The odds ratio values of AUCC0-60 , AUCC0-120 , AUCC0-180 , AUCC0-60 /AUCG0-60 , AUCC0-120 /AUCG0-120 , AUCC0-180 /AUCG0-180 , AUCC60-120 , AUCC60-180 , AUCC120-180 , AUCC60-120 /AUCG60-120 , AUCC60-180 /AUCG60-180 and AUCC120-180 /AUCG120-180 were 0.817 (0.750, 0.890), 0.925 (0.895, 0.955), 0.951 (0.932, 0.970), 0.143 (0.060, 0.340), 0.194 (0.093, 0.406), 0.223 (0.116, 0.427), 0.886 (0.842, 0.933), 0.939 (0.915, 0.963), 0.887 (0.846, 0.930), 0.253 (0.133, 0.479), 0.282 (0.160, 0.497) and 0.355 (0.220, 0.573), respectively. AUCC showed a non-linear relationship with DR, with an inflection point. The inflection points of AUCC180 /AUCG180 , AUCC60-120 , AUCC60-180 , AUCC120-180 , AUCC60-120 /AUCG60-120 , AUCC60-180 /AUCG60-180 , AUCC120-180 /AUCG120-180 and DR were 17.51, 0.542, 6.6, 15.7, 8.23, 0.534, 0.593 and 0.808 (P < 0.0001). When the indexes related to the AUCC were less than the inflection point value, they were significantly negatively associated with DR.

CONCLUSIONS

The indexes related to the AUCC for six time periods during an oral glucose tolerance test and C-peptide release test was closely associated with the incidence to DR in patients with type 2 diabetes. AUCC has the added advantage of being a cheap and convenient risk assessment over traditional ophthalmic screening.

Vascular calcification and cellular signaling pathways as potential therapeutic targets

Increased vascular calcification (VC) is observed in patients with cardiovascular diseases such as atherosclerosis, diabetes, and chronic kidney disease. VC is divided into three types according to its location: intimal, medial, and valvular. Various cellular signaling pathways are associated with VC, including the Wnt, mitogen-activated protein kinase, phosphatidylinositol-3 kinase/Akt, cyclic nucleotide-dependent protein kinase, protein kinase C, calcium/calmodulin-dependent kinase II, adenosine monophosphate-activated protein kinase/mammalian target of rapamycin, Ras homologous GTPase, apoptosis, Notch, and cytokine signaling pathways. In this review, we discuss the literature concerning the key cellular signaling pathways associated with VC and their role as potential therapeutic targets. Inhibitors to these pathways represent good candidates for use as potential therapeutic agents for the prevention and treatment of VC.

Role of galectin-3 in vascular calcification

Vascular calcification is an abnormal process in which bone specific hydroxyapatite crystals are actively deposited on the vascular wall mediated by phenotypic differentiated smooth muscle cells and other mesenchymal cells under various pathological conditions. It is one of the important characteristics in the occurrence and development of atherosclerosis, prevalent in patients with type 2 diabetes and advanced chronic kidney disease, especially those requiring maintenance hemodialysis, with severely threatening human health. Previous studies have shown that the early diagnosis and control of vascular calcification is of great significance for cardiovascular risk stratification, prevention of acute cardiovascular events, which can greatly improve the prognosis and quality of life of patients. Galectins are a family of lectin superfamily. It is widely distributed in various animals and plays an important role in many physiological and pathological processes, such as cell adhesion, apoptosis, inflammatory response, tumor metastasis and so on. Many biomarker-and association-related studies and Preclinical-mechanistic studies have suggested that galactose-specific lectin-3 (galectin-3) plays an important role in vascular calcification and vascular intimal calcification (VIC) calcification induced by Wnt/βcatenin signaling pathway, NF-κB signaling pathway and ERK1/2 signaling pathway. This paper mainly expounds the role and mechanism of galectin-3 in vascular calcification under different pathological conditions including atherosclerosis, diabetes and chronic kidney disease.

Saturated fatty acid promotes calcification via suppressing SIRT6 expression in vascular smooth muscle cells

BACKGROUND

This study aims to investigate the effects of saturated free fatty acid on calcification and SIRT6 expression in vascular smooth muscle cells (VSMCs) and the role of SIRT6 in regulating VSMC calcification.

METHODS

Sprague-Dawley rats were randomly allocated to two groups: rats with normal diet (ND) and high-fat diet (HFD) from 4 to 12 weeks. At 12 weeks, part rats randomly selected from ND and HFD were administrated with vitamin D3 and nicotine to establish a model of vascular calcification. Thoracic aortas were collected from treatment rats at 16 weeks for assaying vascular calcification and related protein expression. Primary VSMCs isolated from Sprague-Dawley rats were used for investigating the effects of palmitic acid on VSMCs' calcification, apoptosis and target protein expression.

RESULTS

HFD-facilitated calcification in medial aorta, with decreased SIRT6 expression in VSMCs of aortas. Palmitic acid decreased SIRT6 expression while increased calcification, apoptosis and protein expression of BMP2 and RUNX2 in primary VSMCs. Overexpression of SIRT6 could, partially or completely, rescue the palmitic acid-induced elevation of calcification, apoptosis and expression of BMP2 and RUNX2.

CONCLUSION

This study demonstrated that vascular calcification induced by HFD was linked to the palmitic acid-induced downregulation of SIRT6. Overexpression of SIRT6 could decrease palmitic acid-induced calcification and apoptosis in VSMCs.

Vascular calcification: Molecular mechanisms and therapeutic interventions

Vascular calcification (VC) is recognized as a pathological vascular disorder associated with various diseases, such as atherosclerosis, hypertension, aortic valve stenosis, coronary artery disease, diabetes mellitus, as well as chronic kidney disease. Therefore, it is a life-threatening state for human health. There were several studies targeting mechanisms of VC that revealed the importance of vascular smooth muscle cells transdifferentiating, phosphorous and calcium milieu, as well as matrix vesicles on the progress of VC. However, the underlying molecular mechanisms of VC need to be elucidated. Though there is no acknowledged effective therapeutic strategy to reverse or cure VC clinically, recent evidence has proved that VC is not a passive irreversible comorbidity but an active process regulated by many factors. Some available approaches targeting the underlying molecular mechanism provide promising prospects for the therapy of VC. This review aims to summarize the novel findings on molecular mechanisms and therapeutic interventions of VC, including the role of inflammatory responses, endoplasmic reticulum stress, mitochondrial dysfunction, iron homeostasis, metabolic imbalance, and some related signaling pathways on VC progression. We also conclude some recent studies on controversial interventions in the clinical practice of VC, such as calcium channel blockers, renin-angiotensin system inhibitions, statins, bisphosphonates, denosumab, vitamins, and ion conditioning agents.

Endoplasmic Reticulum Stress and Pathogenesis of Vascular Calcification

Vascular calcification (VC) is characterized by calcium phosphate deposition in blood vessel walls and is associated with many diseases, as well as increased cardiovascular morbidity and mortality. However, the molecular mechanisms underlying of VC development and pathogenesis are not fully understood, thus impeding the design of molecular-targeted therapy for VC. Recently, several studies have shown that endoplasmic reticulum (ER) stress can exacerbate VC. The ER is an intracellular membranous organelle involved in the synthesis, folding, maturation, and post-translational modification of secretory and transmembrane proteins. ER stress (ERS) occurs when unfolded/misfolded proteins accumulate after a disturbance in the ER environment. Therefore, downregulation of pathological ERS may attenuate VC. This review summarizes the relationship between ERS and VC, focusing on how ERS regulates the development of VC by promoting osteogenic transformation, inflammation, autophagy, and apoptosis, with particular interest in the molecular mechanisms occurring in various vascular cells. We also discuss, the therapeutic effects of ERS inhibition on the progress of diseases associated with VC are detailed.

Vitexin attenuates non-alcoholic fatty liver disease (NAFLD) lipid accumulation in high fat-diet fed mice by activating autophagy and reducing endoplasmic reticulum (ER) stress in liver

Non-alcoholic fatty liver disease (NAFLD) has become prevalent worldwide, but sufficient pharmaceutical treatments for this condition are lacking. Previous literature suggests that vitexin offers beneficial effects in the treatment of NAFLD, but the underlying mechanisms are not well understood. In this study, the in vivo effects of vitexin were investigated in high-fat-diet (HFD)-induced NAFLD mice. Liver pathology, biochemical parameters, lipid levels, hepatocyte ultrastructure, and related regulatory proteins were measured at the end of treatment. Treatment consisted of four weeks of daily administration of vitexin at a dose of 6 mg/kg of body weight. This treatment markedly improved hepatic architecture, attenuated lipid accumulation, and regulated lipid abnormalities. In addition, the treatment reduced endoplasmic reticulum (ER) stress, restored mitochondrial biological proteins, and increased autophagy. Furthermore, the treatment increased PPAR-r protein, which was inhibited by HFD. Thus, it was speculated that vitexin degraded lipids in HFD-induced NAFLD mice liver by inducing autophagy and restoring both ER and mitochondrial biological proteins.

Ameliorative effect of allicin on vascular calcification via inhibiting endoplasmic reticulum stress

OBJECTIVES

Vascular calcification (VC) is an independent predictor for cardiovascular events and mortality. However, there are currently no effective methods to reverse or prevent it. The present study aimed to determine the ameliorative effect of allicin on VC.

METHODS

VC model of rats was induced by high-dose vitamin D₃, which was valued by Alizarin Red staining, calcium contents, and alkaline phosphatase in the aorta. Systolic blood pressure, pulse pressure, and pulse wave velocity were measured to determine aortic stiffness. Protein levels were detected by Western blot.

RESULTS

Allicin treatment rescued aortic VC and stiffness. The increased protein levels of RUNX2 and BMP2, two markers of osteoblastic phenotype of vascular smooth muscle cells, in the calcified aorta were attenuated by allicin, whereas the decreased levels of calponin and SM22α induced by calcification were improved. Allicin treatment significantly attenuated the increased protein levels of GRP78, GRP94, and CHOP, which are key markers of endoplasmic reticulum stress, in the calcified aorta. The activation of PERK/eIF2α/ATF4 cascades was also prevented by allicin.

CONCLUSIONS

Allicin could ameliorate aortic VC and stiffness. The ameliorative effect of allicin on VC might be mediated by inhibiting PERK/eIF2α/ATF4 cascades. Our results might provide a new proof for VC treatment.

Glucose Variability: How Does It Work?

A growing body of evidence points to the role of glucose variability (GV) in the development of the microvascular and macrovascular complications of diabetes. In this review, we summarize data on GV-induced biochemical, cellular and molecular events involved in the pathogenesis of diabetic complications. Current data indicate that the deteriorating effect of GV on target organs can be realized through oxidative stress, glycation, chronic low-grade inflammation, endothelial dysfunction, platelet activation, impaired angiogenesis and renal fibrosis. The effects of GV on oxidative stress, inflammation, endothelial dysfunction and hypercoagulability could be aggravated by hypoglycemia, associated with high GV. Oscillating hyperglycemia contributes to beta cell dysfunction, which leads to a further increase in GV and completes the vicious circle. In cells, the GV-induced cytotoxic effect includes mitochondrial dysfunction, endoplasmic reticulum stress and disturbances in autophagic flux, which are accompanied by reduced viability, activation of apoptosis and abnormalities in cell proliferation. These effects are realized through the up- and down-regulation of a large number of genes and the activity of signaling pathways such as PI3K/Akt, NF-κB, MAPK (ERK), JNK and TGF-β/Smad. Epigenetic modifications mediate the postponed effects of glucose fluctuations. The multiple deteriorative effects of GV provide further support for considering it as a therapeutic target in diabetes.

Apoptosis in the Extraosseous Calcification Process

Extraosseous calcification is a pathologic mineralization process occurring in soft connective tissues (e.g., skin, vessels, tendons, and cartilage). It can take place on a genetic basis or as a consequence of acquired chronic diseases. In this last case, the etiology is multifactorial, including both extra- and intracellular mechanisms, such as the formation of membrane vesicles (e.g., matrix vesicles and apoptotic bodies), mitochondrial alterations, and oxidative stress. This review is an overview of extraosseous calcification mechanisms focusing on the relationships between apoptosis and mineralization in cartilage and vascular tissues, as these are the two tissues mostly affected by a number of age-related diseases having a progressively increased impact in Western Countries.

Macrophage galectin-3 enhances intimal translocation of vascular calcification in diabetes mellitus

The clinical risks and prognosis of diabetic vascular intimal calcification (VIC) and medial calcification (VMC) are different. This study aims to investigate the mechanism of VIC/VMC translocation. Anterior tibial arteries were collected from patients with diabetic foot amputation. The patients were then divided into VIC and VMC groups. There were plaques in all anterior tibial arteries, while the enrichment of galectin-3 in arterial plaques in the VIC group was significantly higher than that in the VMC group. Furthermore, a macrophage/vascular smooth muscle cell (VSMC) coculture system was constructed. VSMC-derived extracellular vesicles (EVs) was labeled with fluorescent probe. After macrophages were pretreated with recombinant galectin-3 protein, the migration of VSMC-derived EVs and VSMC-derived calcification was more pronounced. And anti-galectin-3 antibody can inhibit this process of EVs and calcification translocation. Then, lentivirus (LV)-treated bone marrow cells (BMCs) were transplanted into apolipoprotein E-deficient (ApoE^-/-) mice, and a diabetic atherosclerosis mouse model was constructed. After 15 wk of high-fat diet, ApoE^-/- mice transplanted with LV-shgalectin-3 BMCs exhibited medial calcification and a concentrated distribution of EVs in the media. In conclusion, upregulation of galectin-3 in macrophages promotes the migration of VSMC-derived EVs to the intima and induces diabetic vascular intimal calcification.NEW & NOTEWORTHY The clinical risk and prognosis of vascular intimal and medial calcification are different. Macrophage galectin-3 regulates the migration of vascular smooth muscle cell-derived extracellular vesicles and mediates diabetic vascular intimal/medial calcification translocation. This study may provide insights into the early intervention in diabetic vascular calcification.