Glucagon-like peptide-1 receptor agonist activation ameliorates venous thrombosis-induced arteriovenous fistula failure in chronic kidneyd isease

Research progress on post-translational modification of proteins and cardiovascular diseases

Cardiovascular diseases (CVDs) such as atherosclerosis, myocardial remodeling, myocardial ischemia-reperfusion (I/R) injury, heart failure, and oxidative stress are among the greatest threats to human health worldwide. Cardiovascular pathogenesis has been studied for decades, and the influence of epigenetic changes on CVDs has been extensively studied. Post-translational modifications (PTMs), including phosphorylation, glycosylation, methylation, acetylation, ubiquitination, ubiquitin-like and nitrification, play important roles in the normal functioning of the cardiovascular system. Over the past decade, with the application of high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), an increasing number novel acylation modifications have been discovered, including propionylation, crotonylation, butyrylation, succinylation, lactylation, and isonicotinylation. Each change in protein conformation has the potential to alter protein function and lead to CVDs, and this process is usually reversible. This article summarizes the mechanisms underlying several common PTMs involved in the occurrence and development of CVDs.

Sodium thiosulfate through preserving mitochondrial dynamics ameliorates oxidative stress induced renal apoptosis and ferroptosis in 5/6 nephrectomized rats with chronic kidney diseases

Chronic kidney disease (CKD) progression may be evoked through dysregulated mitochondrial dynamics enhanced oxidative stress and inflammation contributing to high cardiovascular morbidity and mortality. Previous study has demonstrated sodium thiosulfate (STS, Na2S2O3) could effectively attenuate renal oxidative injury in the animal model of renovascular hypertension. We explored whether the potentially therapeutic effect of STS is available on the attenuating CKD injury in thirty-six male Wistar rats with 5/6 nephrectomy. We determined the STS effect on reactive oxygen species (ROS) amount in vitro and in vivo by an ultrasensitive chemiluminescence-amplification method, ED-1 mediated inflammation, Masson's trichrome stained fibrosis, mitochondrial dynamics (fission and fusion) and two types of programmed cell death, apoptosis and ferroptosis by western blot and immunohistochemistry. Our in vitro data showed STS displayed the strongest scavenging ROS activity at the dosage of 0.1 g. We applied STS at 0.1 g/kg intraperitoneally 5 times/week for 4 weeks to these CKD rats. CKD significantly enhanced the degree in arterial blood pressure, urinary protein, BUN, creatinine, blood and kidney ROS amount, leukocytes infiltration, renal 4-HNE expression, fibrosis, dynamin-related protein 1 (Drp1) mediated mitochondrial fission, Bax/c-caspase 9/c-caspase 3/poly (ADP-ribose) polymerase (PARP) mediated apoptosis, iron overload/ferroptosis and the decreased xCT/GPX4 expression and OPA-1 mediated mitochondrial fusion. STS treatment significantly ameliorated oxidative stress, leukocyte infiltration, fibrosis, apoptosis and ferroptosis and improved mitochondrial dynamics and renal dysfunction in CKD rats. Our results suggest that STS as drug repurposing strategy could attenuate CKD injury through the action of anti-mitochondrial fission, anti-inflammation, anti-fibrosis, anti-apoptotic, and anti-ferroptotic mechanisms.

The association of urinary prostaglandins with uric acid in hyperuricemia patients

Purpose

To explore the association between uric acid and urinary prostaglandins in male patients with hyperuricemia.

Methods

A total of 38 male patients with hyperuricemia in outpatients of Huadong Hospital from July 2018 to January 2020 were recruited. Serum uric acid (SUA), 24 h urinary uric acid excretion and other indicators were detected respectively. 10 ml urine was taken to determine prostaglandin prostaglandin D (PGD), prostaglandin E1 (PGE1), prostaglandin E2 (PGE2), 6-keto-PGF1α, thromboxane A2 (TXA2) and thromboxane B2 (TXB2). Fraction of uric acid excretion (FEua) and uric acid clearance rate (Cua) were calculated. According to the mean value of FEua and Cua, patients were divided into two groups, respectively. The independent-samples t test and the Mann–Whitney U test were applied for normally and non-normally distributed data, respectively.

Results

After adjusting confounding factors (age, BMI, eGFR, TG, TC, HDL and LDL), SUA was negatively correlated with urinary PGE1(r = -0.615, P = 0.009) and PGE2(r = -0.824, P < 0.001). Compared with SUA1 group (SUA < 482.6 mg/dl), SUA2 (SUA \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ge$$\end{document}≥ 482.6 mg/dl) had lower urinary PGE1(P = 0.022) and PGE2(P = 0.019) levels. Cua was positively correlated with PGE2 (r = 0.436, P = 0.01). The correlation persisted after adjustment for age, BMI, eGFR, TG, TC, HDL and LDL by multiple linear regression analysis. In the Cua1 group (Cua < 4.869 mL /min/1.73 m²), PGE2 were lower than that in Cua2 (Cua \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ge$$\end{document}≥ 4.869 mL /min/1.73 m²) group (P = 0.011).

Conclusions

In male patients with hyperuricemia, SUA was negatively correlated with urinary PGE2, Cua was positively correlated with urinary PGE2. Urinary PGE2 were significantly different between different SUA and Cua groups.

DPP4 Promotes Human Endothelial Cell Senescence and Dysfunction via the PAR2-COX-2-TP Axis and NLRP3 Inflammasome Activation

BACKGROUND

Abnormal accumulation of senescent cells in the vessel wall leads to a compromised vascular function contributing to vascular aging. Soluble DPP4 (dipeptidyl peptidase 4; sDPP4) secretion from visceral adipose tissue is enhanced in obesity, now considered a progeric condition. sDPP4 triggers vascular deleterious effects, albeit its contribution to vascular aging is unknown. We aimed to explore sDPP4 involvement in vascular aging, unraveling the molecular pathway by which sDPP4 acts on the endothelium.

METHODS

Human endothelial cell senescence was assessed by senescence-associated β-galactosidase assay, visualization of DNA damage, and expression of prosenescent markers, whereas vascular function was evaluated by myography over human dissected microvessels. In visceral adipose tissue biopsies from a cohort of obese patients, we explored several age-related parameters in vitro and ex vivo.

RESULTS

By a common mechanism, sDPP4 triggers endothelial cell senescence and endothelial dysfunction in isolated human resistance arteries. sDPP4 activates the metabotropic receptor PAR2 (protease-activated receptor 2), COX-2 (cyclooxygenase 2) activity, and the production of TXA₂ (thromboxane A2) acting over TP (thromboxane receptor) receptors (PAR2-COX-2-TP axis), leading to NLRP3 (nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain-containing 3) inflammasome activation. Obese patients exhibited impaired microarterial functionality in comparison to control nonobese counterparts. Importantly, endothelial dysfunction in obese patients positively correlated with greater expression of DPP4, prosenescent, and proinflammatory markers in visceral adipose tissue nearby the resistance arteries. Moreover, when DPP4 activity or sDPP4-induced prosenescent mechanism was blocked, endothelial dysfunction was restored back to levels of healthy subjects.

CONCLUSIONS

These results reveal sDPP4 as a relevant mediator in early vascular aging and highlight its capacity activating main proinflammatory mediators in the endothelium that might be pharmacologically tackled.

Long-Lasting Exendin-4-Loaded PLGA Nanoparticles Ameliorate Cerebral Ischemia/Reperfusion Damage in Diabetic Rats

Exendin-4 (Ex-4) is an incretin mimetic agent approved for diabetes treatment and neuronal protection. However, the required frequent injections restrict its clinical application. We prepared Ex-4-loaded poly(d,l-lactide-co-glycolide) nanoparticles (PEx-4) and investigated their effect on cerebral ischemia/reperfusion (IR) injury associated with micturition center damage-induced cystopathy in diabetic rats. Using ten minutes of bilateral carotid artery occlusion combined with hemorrhage-induced hypotension of the IR model in streptozotocin-induced type 1 diabetic (T1DM) Wistar rats, we compared the effects of Ex-4 and PEx-4 on prefrontal cortex edema, voiding function and oxidative stress including cerebral spinal fluid (CSF) reference H₂O₂ (RH₂O₂) and HOCl (RHOCl) levels, endoplasmic reticulum (ER) stress, apoptosis, autophagy and pyroptosis signaling in brain and bladder by Western blot and immunohistochemistry. Single injection of PEx-4 displayed higher CSF antioxidant activity and a long-lasting hypoglycemic effect compared to Ex-4 in rats. T1DM and IR primarily enhanced CSF RH₂O₂, and pIRE-1/caspase-12/pJNK/CHOP-mediated ER stress, caspase-3/PARP-mediated apoptosis, Beclin-1/LC3B-mediated autophagy and caspase-1/IL-1β-mediated pyroptosis signaling in the damaged brains. Our data further evidenced that PEx-4 were more efficient than Ex-4 in attenuating IR-evoked prefrontal cortex edema, the impairment in micturition center and the enhanced level of CSF RH₂O₂ and HOCl, ER stress, apoptosis, autophagy and pyroptosis parameters in the damaged brains, but had less of an effect on IR-induced voiding dysfunction in bladders of T1DM rats. In summary, PEx-4 with stronger antioxidant activity and long-lasting bioavailability may efficiently confer therapeutic efficacy to ameliorate IR-evoked brain damage through the inhibitory action on oxidative stress, ER stress, apoptosis, autophagy and pyroptosis signaling in diabetic rats.

Effects of Antidiabetic Drugs on Endothelial Function in Patients With Type 2 Diabetes Mellitus: A Bayesian Network Meta-Analysis

BACKGROUND

The changes of endothelial function in type 2 diabetes mellitus (T2DM) patients are closely associated with the development of cardiovascular disease (CVD). However, it is still unclear whether commonly used antidiabetic drugs can improve endothelial function. Flow-mediated dilation (FMD) is a noninvasive tool for evaluating endothelial function, which typically examines changes in the brachial artery diameter in response to ischemia using ultrasound. We performed a network meta-analysis (NMA) to explore the associations between changes in endothelial function and antidiabetic drugs by evaluating FMD in T2DM patients.

METHODS

We systematically searched several electronic databases for randomized controlled trials (RCTs) published from inception until January 25, 2022 with no language restriction. The primary outcome was FMD change in all studies, and we performed subgroup analysis in T2DM patients without CVD. NMA was performed to calculate the mean differences (MDs) with 95% confidence intervals (CIs).

RESULTS

From the 1,987 candidate articles identified in the initial search, 30 RCTs were eventually included in the analysis. In all studies, glucagon-like peptide-1 receptor (GLP-1R) agonists [MD = 3.70 (1.39-5.97)], TZD [MD = 1.96 (0.006-3.89)] produced improvement of FMD change compared to lifestyle intervention. GLP-1R agonists [MD = 3.33 (1.36-5.34) and MD = 3.30 (1.21-5.43)] showed significantly greater improvements in FMD change in pairwise comparisons with sulfonylureas and placebo. SGLT-2i also showed efficacy compared to sulfonylureas (MD = 1.89, 95% CI, 0.10, 3.75). In studies of T2DM patients without CVD, GLP-1R agonists [MD = 3.53 (1.24-5.76)], and TZD [MD = 2.30 (0.27-3.24)] produced improvements in FMD change compared to lifestyle treatment. GLP-1R agonists [MD = 3.25 (1.13-5.40), and MD = 3.85 (1.68-6.13)] showed significantly greater improvements in pairwise comparisons with sulfonylureas, and placebo.

CONCLUSION

In T2DM patients, both GLP-1R agonists, SGLT-2i and TZD have favorable effects to improve endothelial function in T2DM patients. In T2DM patients without CVD, GLP-1R agonists had a greater effect to improve endothelial function than sulfonylureas. These suggested that GLP-1R agonists are associated with significantly improved endothelial function in T2DM patients.

Medical and Surgical Obesity Treatments and Atherosclerosis: Mechanisms beyond Typical Risk Factors

PURPOSE OF REVIEW

This study aims to discuss the mechanisms by which GLP-1 agonists and bariatric surgery improve cardiovascular outcomes in severely obese patients.

RECENT FINDINGS

Recent studies have demonstrated that both GLP-1 agonist use and bariatric surgery reduce adverse cardiovascular outcomes. Improvements in traditional atherosclerosis risk factors in association with weight loss likely contribute, but weight loss-independent mechanisms are also suggested to have roles. We review the clinical and preclinical evidence base for cardiovascular benefit of LP-1 agonists and bariatric surgery beyond traditional risk factors, including improvements in endothelial function, direct impacts on atherosclerotic plaques, and anti-inflammatory effects.

Use of Anti-Diabetic Agents in Non-Diabetic Kidney Disease: From Bench to Bedside

New drugs were recently developed to treat hyperglycemia in patients with type 2 diabetes mellitus (T2D). However, metformin remains the first-line anti-diabetic agent because of its cost-effectiveness. It has pleiotropic action that produces cardiovascular benefits, and it can be useful in diabetic nephropathy, although metformin-associated lactic acidosis is a hindrance to its use in patients with kidney failure. New anti-diabetic agents, including glucagon-like peptide-1 receptor (GLP-1R) agonists, dipeptidyl peptidase-4 (DPP-4) inhibitors, and sodium-glucose transporter-2 (SGLT-2) inhibitors, also produce cardiovascular or renal benefits in T2D patients. Their glucose-independent beneficial actions can lead to cardiorenal protection via hemodynamic stabilization and inflammatory modulation. Systemic hypertension is relieved by natriuresis and improved vascular dysfunction. Enhanced tubuloglomerular feedback can be restored by SGLT-2 inhibition, reducing glomerular hypertension. Patients with non-diabetic kidney disease might also benefit from those drugs because hypertension, proteinuria, oxidative stress, and inflammation are common factors in the progression of kidney disease, irrespective of the presence of diabetes. In various animal models of non-diabetic kidney disease, metformin, GLP-1R agonists, DPP-4 inhibitors, and SGLT-2 inhibitors were favorable to kidney morphology and function. They strikingly attenuated biomarkers of oxidative stress and inflammatory responses in diseased kidneys. However, whether those animal results translate to patients with non-diabetic kidney disease has yet to be evaluated. Considering the paucity of new agents to treat kidney disease and the minimal adverse effects of metformin, GLP-1R agonists, DPP-4 inhibitors, and SGLT-2 inhibitors, these anti-diabetic agents could be used in patients with non-diabetic kidney disease. This paper provides a rationale for clinical trials that apply metformin, GLP-1R agonists, DPP-4 inhibitors, and SGLT-2 inhibitors to non-diabetic kidney disease.

Glucose-responsive hydrogel enhances the preventive effect of insulin and liraglutide on diabetic nephropathy of rats

Diabetic nephropathy (DN) is one of the most serious complications of diabetes mellitus. The combination of insulin (Ins) with liraglutide (Lir) has a greater potential for preventing DN than monotherapy. However, the renal protective effect of the combined Ins/Lir therapy is largely compromised due to their short half-lives after subcutaneous injection. Herein, a glucose-responsive hydrogel was designed in situ forming the dynamic boronic esters bonds between phenylboronic acid-grafted γ-Polyglutamic acid (PBA-PGA) and konjac glucomannan (KGM). It was hypothesized that the KGM/PBA-PGA hydrogel as the delivery vehicle of Ins/Lir would enhance the combinational effect of the latter on preventing the DN progress. Scan electronic microscopy and rheological studies showed that KGM/PBA-PGA hydrogel displayed good glucose-responsive property. Besides, the glucose-sensitive release profile of either Ins or Lir from KGM/PBA-PGA hydrogel was uniformly displayed at hyperglycemic level. Furthermore, the preventive efficacy of KGM/PBA-PGA hydrogel incorporating insulin and liraglutide (Ins/Lir-H) on DN progress was evaluated on streptozotocin-induced rats with diabetic mellitus (DM). At 6 weeks after subcutaneous injection of Ins/Lir-H, not only the morphology of kidneys was obviously recovered as shown by ultrasonography, but also the renal hemodynamics was significantly improved. Meanwhile, the 24-h urinary protein and albumin/creatinine ratio were well modulated. Inflammation and fibrosis were also largely inhibited. Besides, the glomerular NPHS-2 was obviously elevated after treatment with Ins/Lir-H. The therapeutic mechanism of Ins/Lir-H was highly associated with the alleviation of oxidative stress and activation of autophagy. Conclusively, the better preventive effect of the combined Ins/Lir via KGM/PBA-PGA hydrogel on DN progress was demonstrated as compared with their mixed solution, suggesting KGM/PBA-PGA hydrogel might be a potential vehicle of Ins/Lir to combat the progression of DN.

A Review on the Effects of New Anti-Diabetic Drugs on Platelet Function

BACKGROUND

Cardiovascular complications account for the majority of deaths caused by diabetes mellitus. Platelet hyperactivity has been shown to increase the risk of thrombotic events and is a therapeutic target for their prevention in diabetes. Modulation of platelet function by diabetes agents in addition to their hypoglycemic effects would contribute to cardiovascular protection. Newly introduced antidiabetic drugs of sodium-glucose cotransporter 2 inhibitors (SGLT2i), glucagon like peptide-1 receptor agonists (GLP-1RA) and dipeptidyl peptidase-4 inhibitors may have anti-platelet effects, and in the case of SGLT2i and GLP-1RA may contribute to their proven cardiovascular benefit that has been shown clinically.

OBJECTIVE

Here, we reviewed the potential effects of these agents on platelet function in diabetes.

RESULTS AND CONCLUSION

GLP-1RA and DPP-4i drugs have antiplatelet properties beyond their primary hypoglycemic effects. Whilst we have little direct evidence for the antiplatelet effects of SGLT2 inhibitors, some studies have shown that these agents may inhibit platelet aggregation and reduce the risk of thrombotic events in diabetes.

Interleukin-9 mediates chronic kidney disease-dependent vein graft disease: a role for mast cells

Aims

Chronic kidney disease (CKD) is a powerful independent risk factor for cardiovascular events, including vein graft failure. Because CKD impairs the clearance of small proteins, we tested the hypothesis that CKD exacerbates vein graft disease by elevating serum levels of critical cytokines that promote vein graft neointimal hyperplasia.

Methods and results

We modelled CKD in C57BL/6 mice with 5/6ths nephrectomy, which reduced glomerular filtration rate by 60%, and we modelled vein grafting with inferior-vena-cava-to-carotid interposition grafting. CKD increased vein graft neointimal hyperplasia four-fold, decreased vein graft re-endothelialization two-fold, and increased serum levels of interleukin-9 (IL-9) five-fold. By quantitative immunofluorescence and histochemical staining, vein grafts from CKD mice demonstrated a ∼two-fold higher prevalence of mast cells, and a six-fold higher prevalence of activated mast cells. Concordantly, vein grafts from CKD mice showed higher levels of TNF and NFκB activation, as judged by phosphorylation of NFκB p65 on Ser536 and by expression of VCAM-1. Arteriovenous fistula veins from humans with CKD also showed up-regulation of mast cells and IL-9. Treating CKD mice with IL-9-neutralizing IgG reduced vein graft neointimal area four-fold, increased vein graft re-endothelialization ∼two-fold, and reduced vein graft total and activated mast cell levels two- and four-fold, respectively. Treating CKD mice with the mast cell stabilizer cromolyn reduced neointimal hyperplasia and increased re-endothelialization in vein grafts. In vitro, IL-9 promoted endothelial cell apoptosis but had no effect on smooth muscle cell proliferation.

Conclusion

CKD aggravates vein graft disease through mechanisms involving IL-9 and mast cell activation.

Prostaglandins in the pathogenesis of kidney diseases

Prostaglandins (PGs) are important lipid mediators produced from arachidonic acid via the sequential catalyzation of cyclooxygenases (COXs) and specific prostaglandin synthases. There are five subtypes of PGs, namely PGE2, PGI2, PGD2, PGF2α, and thromboxane A2 (TXA2). PGs exert distinct roles by combining to a diverse family of membrane-spanning G protein-coupled prostanoid receptors. The distribution of these PGs, their specific synthases and receptors vary a lot in the kidney. This review summarized the recent findings of PGs together with the COXs and their specific synthases and receptors in regulating renal function and highlighted the insights into their roles in the pathogenesis of various kidney diseases.

Catechins Blunt the Effects of oxLDL and its Primary Metabolite Phosphatidylcholine Hydroperoxide on Endothelial Dysfunction Through Inhibition of Oxidative Stress and Restoration of eNOS in Rats

BACKGROUND/AIMS

We explored the effects of catechins (decaffeinated green tea extracts containing (-)-epicatechin, (-)-epigallocatechin, (-)-epicatechin gallate and (-)-epigallocatechin gallate) on atherosclerosis risk factors, oxidized low-density lipoprotein (oxLDL) and its primary metabolite, phosphatidylcholine hydroperoxide (PCOOH) induced oxidative injury in cultured endothelial cell line and rats.

METHODS

We used endothelial cell line and male Wistar rats to determine the effect of catechins on oxLDL or PCOOH induced oxidative injury including apoptosis, H2O2 level, vascular responses and urinary 8-isoprostane and nitrite/nitrate concentration. Plasma catechins concentration was determined by a CoulArray HPLC. Responses of aortic and renal vasoconstriction were evaluated by a transonic meter and a full-field laser perfusion imager.

RESULTS

PCOOH administration significantly increased H2O2 amounts and cell apoptosis and decreased endothelial nitric oxide synthase (eNOS) expression in the cultured endothelial cells. Catechins pretreatment significantly reduced PCOOH-elevated H2O2 amounts, endothelial cell apoptosis and partly recovered eNOS expression. Intravenous administration of oxLDL, PCOOH or H2O2, not native LDL, significantly decreased renal and aortic blood flow associated with enhanced ICAM-1 expression and 4-hydroxynoneal (4-HNE) accumulation, and decreased eNOS expression in the male Wistrar rats. One hour after oral intake of green tea extracts, 4 peaks of catechins were found in the rat plasma. The increased plasma catechins significantly inhibited oxLDL-, PCOOH- or H2O2-induced renal and aortic vasoconstriction, decreased urinary 8-isoprostane levels, renal ICAM-1 expression and 4-HNE accumulation, and restored nitrite/nitrate amounts and eNOS activity.

CONCLUSIONS

Our data suggests that catechins pretreatment decrease PCOOH-induced endothelial apoptosis and arterial vasoconstriction through the action of H2O2 inhibition and eNOS restoration.

GLP-1 Inhibits High-Glucose-Induced Oxidative Injury of Vascular Endothelial Cells

The aim of this work was to evaluate the effects of glucagon-like peptide-1 (GLP-1) on high-glucose-induced oxidative stress and investigate the possible mechanisms underlying this process. We measured reactive oxygen species (ROS) production, cell apoptosis, the expression of NOX4 and its subunits, and p47phox translocation in human umbilical vein endothelial cells (HUVECs). An experimental type 2 diabetes model was induced using streptozotocin in male Sprague-Dawley rats. Fasting blood glucose (FBG), fasting insulin (FINS), total cholesterol (TC), triglycerides (TGs), and free fatty acid (FFA) were measured. Histomorphological analysis of the aorta was performed using hematoxylin-eosin staining. NOX4 and VCAM-1 expression in the aorta was measured. We found that high-glucose-induced ROS production and apoptosis were inhibited by GLP-1 treatment. High glucose caused upregulation of NOX4, p47phox, and Rac-1 and translocation of p47phox but had no effect on the cells pretreated with GLP-1. Furthermore, in the diabetic group, FBG, FINS, TG, TC, and FFA were increased, and NOX4 and VCAM-1 levels were also elevated. However, GLP-1 attenuated all these changes. GLP-1 ameliorated high-glucose-induced oxidative stress by inhibiting NOX4, p47phox, and Rac-1 expression and translocation of p47phox, suggesting its clinical usefulness in diabetic vascular complications.

5-fluorouracil causes endothelial cell senescence: potential protective role of glucagon-like peptide 1

BACKGROUND AND PURPOSE

5-fluorouracil (5FU) and its prodrug, capecitabine, can damage endothelial cells, whilst endothelial integrity is preserved by glucagon-like peptide 1 (GLP-1). Here, we studied the effect of 5FU on endothelial senescence and whether GLP-1 antagonizes it.

EXPERIMENTAL APPROACH

EA.hy926 cells were exposed to 5FU or sera from patients taking capecitabine, with or without pre-incubation with GLP-1. Senescence was identified by expression of senescence-associated β-galactosidase and p16^INK4a and reduced cell proliferation. Soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble intercellular adhesion molecule-1 (sICAM-1) and CD146 (marker of endothelial injury) were measured by ELISA before and at completion of capecitabine chemotherapy. RT-PCR, western blotting, functional experiments with signalling inhibitors and ERK1/2 silencing were performed to characterize 5FU-induced phenotype and elucidate the pathways underlying 5FU and GLP-1 activity.

KEY RESULTS

Both 5FU and sera from capecitabine-treated patients stimulated endothelial cell senescence. 5FU-elicited senescence occurred via activation of p38 and JNK, and was associated with decreased eNOS and SIRT-1 levels. Furthermore, 5FU up-regulated VCAM1 and TYMP (encodes enzyme activating capecitabine and 5FU), and sVCAM-1 and CD146 concentrations were higher after than before capecitabine chemotherapy. A non-significant trend for higher ICAM1 levels was also observed. GLP-1 counteracted 5FU-initiated senescence and reduced eNOS and SIRT-1 expression, this protection being mediated by GLP-1 receptor, ERK1/2 and, possibly, PKA and PI3K.

CONCLUSIONS AND IMPLICATIONS

5FU causes endothelial cell senescence and dysfunction, which may contribute to its cardiovascular side effects. 5FU-triggered senescence was prevented by GLP-1, raising the possibility of using GLP-1 analogues and degradation inhibitors to treat 5FU and capecitabine vascular toxicity.

LINKED ARTICLES

This article is part of a themed section on New Insights into Cardiotoxicity Caused by Chemotherapeutic Agents. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.21/issuetoc.

The molecular mechanisms of hemodialysis vascular access failure

The arteriovenous fistula has been used for more than 50 years to provide vascular access for patients undergoing hemodialysis. More than 1.5 million patients worldwide have end stage renal disease and this population will continue to grow. The arteriovenous fistula is the preferred vascular access for patients, but its patency rate at 1 year is only 60%. The majority of arteriovenous fistulas fail because of intimal hyperplasia. In recent years, there have been many studies investigating the molecular mechanisms responsible for intimal hyperplasia and subsequent thrombosis. These studies have identified common pathways including inflammation, uremia, hypoxia, sheer stress, and increased thrombogenicity. These cellular mechanisms lead to increased proliferation, migration, and eventually stenosis. These pathways work synergistically through shared molecular messengers. In this review, we will examine the literature concerning the molecular basis of hemodialysis vascular access malfunction.

The Cardiovascular Biology of Glucagon-like Peptide-1

Glucagon-like peptide-1, produced predominantly in enteroendocrine cells, controls glucose metabolism and energy homeostasis through regulation of islet hormone secretion, gastrointestinal motility, and food intake, enabling development of GLP-1 receptor (GLP-1R) agonists for the treatment of diabetes and obesity. GLP-1 also acts on the immune system to suppress inflammation, and GLP-1R signaling in multiple tissues impacts cardiovascular function in health and disease. Here we review how GLP-1 and clinically approved GLP-1R agonists engage mechanisms that influence the risk of developing cardiovascular disease. We discuss how GLP-1R agonists modify inflammation, cardiovascular physiology, and pathophysiology in normal and diabetic animals through direct and indirect mechanisms and review human studies illustrating mechanisms linking GLP-1R signaling to modification of the cardiovascular complications of diabetes. The risks and benefits of GLP-1R agonists are updated in light of recent data suggesting that GLP-1R agonists favorably modify outcomes in diabetic subjects at high risk for cardiovascular events.

The GLP-1 receptor agonists exendin-4 and liraglutide alleviate oxidative stress and cognitive and micturition deficits induced by middle cerebral artery occlusion in diabetic mice

Background

Glucagon-like peptide 1 (GLP-1) analogs protect a variety of cell types against oxidative damage and vascular and neuronal injury via binding to GLP-1 receptors. This study aimed to investigate the effects of the GLP-1 analogs exendin-4 and liraglutide on cerebral blood flow, reactive oxygen species production, expression of oxidative stress-related proteins, cognition, and pelvic sympathetic nerve-mediated bladder contraction after middle cerebral artery occlusion (MCAO) injury in the db/db mouse model of diabetes.

Results

Sixty minutes of MCAO increased blood and brain reactive oxygen species counts in male db/db mice, as revealed by dihydroethidium staining. MCAO also increased nuclear factor-κB and intercellular adhesion molecule-1 expression and decreased cerebral microcirculation. These effects were attenuated by treatment with exendin-4 or liraglutide. MCAO did not affect basal levels of phosphorylated Akt (p-Akt) or endothelial nitric oxide synthase (p-eNOS); however, exendin-4 and liraglutide treatments significantly enhanced p-Akt and p-eNOS levels, indicating activation of the p-Akt/p-eNOS signaling pathway. MCAO-induced motor and cognitive deficits and micturition dysfunction, indicated by reduced pelvic nerve-mediated voiding contractions and increased nonvoiding contractions, were also partially attenuated by exendin-4 treatment.

Conclusions

The above data indicate that treatment with GLP-1 agonists exerts protective effects against oxidative, inflammatory, and apoptotic damage in brain areas that control parasympathetic/pelvic nerve-mediated voiding contractions and cognitive and motor behaviors in a diabetic mouse model.

Oral treatment with the herbal formula B401 protects against aging-dependent neurodegeneration by attenuating oxidative stress and apoptosis in the brain of R6/2 mice

BACKGROUND

Neurodegeneration is characterized by progressive neurological deficits due to selective neuronal loss in the nervous system. Huntington's disease (HD) is an incurable neurodegenerative disorder. Neurodegeneration in HD patients shows aging-dependent pattern. Our previous study has suggested that a herbal formula B401 may have neuroprotective effects in the brains of R6/2 mice.

OBJECTIVE

To clarify possible mechanisms for neurodegeneration, which improves the understanding the aging process. This study focuses on clarifying neurodegenerative mechanisms and searching potential therapeutic targets in HD patients.

METHODS

The oxidative stress and apoptosis were compared in the brain tissue between R6/2 HD mice with and without oral B401 treatment. Expressions of proteins for oxidative stress and apoptosis in the brain tissue of R6/2 HD mice were examined by using immunostaining and Western blotting techniques.

RESULTS

R6/2 HD mice with oral B401 treatment significantly reduced reactive oxygen species levels in the blood, but markedly increased expressions of superoxide dismutase 2 in the brain tissue. Furthermore, R6/2 HD mice with oral B401 treatment significantly increased expressions of B-cell lymphoma 2 (Bcl-2), but significantly reduced expressions of Bcl-2-associated X protein (Bax), calpain, and caspase-3 in the brain tissue.

CONCLUSION

Our findings provide evidence that the herbal formula B401 can remedy for aging-dependent neurodegeneration of R6/2 mice via suppressing oxidative stress and apoptosis in the brain. We suggest that the herbal formula B401 can be developed as a potential health supplement for ameliorating aging-dependent neurodegeneration.

Exendin-4-loaded PLGA microspheres relieve cerebral ischemia/reperfusion injury and neurologic deficits through long-lasting bioactivity-mediated phosphorylated Akt/eNOS signaling in rats

Glucagon-like peptide-1 (GLP-1) receptor activation in the brain provides neuroprotection. Exendin-4 (Ex-4), a GLP-1 analog, has seen limited clinical usage because of its short half-life. We developed long-lasting Ex-4-loaded poly(D,L-lactide-co-glycolide) microspheres (PEx-4) and explored its neuroprotective potential against cerebral ischemia in diabetic rats. Compared with Ex-4, PEx-4 in the gradually degraded microspheres sustained higher Ex-4 levels in the plasma and cerebrospinal fluid for at least 2 weeks and improved diabetes-induced glycemia after a single subcutaneous administration (20 μg/day). Ten minutes of bilateral carotid artery occlusion (CAO) combined with hemorrhage-induced hypotension (around 30 mm Hg) significantly decreased cerebral blood flow and microcirculation in male Wistar rats subjected to streptozotocin-induced diabetes. CAO increased cortical O2(-) levels by chemiluminescence amplification and prefrontal cortex edema by T2-weighted magnetic resonance imaging analysis. CAO significantly increased aquaporin 4 and glial fibrillary acidic protein expression and led to cognition deficits. CAO downregulated phosphorylated Akt/endothelial nitric oxide synthase (p-Akt/p-eNOS) signaling and enhanced nuclear factor (NF)-κBp65/intercellular adhesion molecule-1 (ICAM-1) expression, endoplasmic reticulum (ER) stress, and apoptosis in the cerebral cortex. PEx-4 was more effective than Ex-4 to improve CAO-induced oxidative injury and cognitive deficits. The neuroprotection provided by PEx-4 was through p-Akt/p-eNOS pathways, which suppressed CAO-enhanced NF-κB/ICAM-1 signaling, ER stress, and apoptosis.

Oral treatment with the herbal formula B307 alleviates cardiac toxicity in doxorubicin-treated mice via suppressing oxidative stress, inflammation, and apoptosis

OBJECTIVE

This study aimed to investigate whether the herbal formula B307 could alleviate doxorubicin (DOX)-induced acute cardiotoxicity. If so, we further unraveled possible molecular mechanisms of cardiac protection under treatment with the herbal formula B307.

METHODS

Before the animal experiment, we examined relative viabilities of Huh7 cancer cells under treatment with the herbal formula B307. To test whether oral treatment with the herbal formula B307 could alleviate cardiotoxicity, equal volumes of B307 (50 mg/kg) or saline (sham treatment) were administered to 20-week-old male mice once daily for 14 consecutive days. Then, DOX (10 mg/kg; ip) was administered to male mice under B307 and sham treatments at 22-23 weeks of age. Cardiac functions in these mice were assessed via echocardiography at 23-24 weeks of age. Then, expressions of oxidative stress, inflammation, and apoptosis-related proteins were examined in the heart tissue by immunohistochemistry and Western blotting at 24-25 weeks of age. Apart from this, mortality rate and body weight were measured during the experiment.

RESULTS

In vitro, the relative viabilities of Huh7 cancer cells under treatment with the herbal formula B307 had shown no obvious change at doses of 10-160 ng/mL. Furthermore, the relative viabilities of Huh7 cancer cells were significantly reduced under DOX treatment but showed no significant change under DOX only and DOX plus B307 treatment. In vivo, the mortality rate, body weight, and cardiac function of DOX-treated mice were obviously improved under oral treatment with the herbal formula B307. Furthermore, cardiac expressions of endothelial nitric oxide synthase, superoxide dismutase 2, and B-cell lymphoma 2 were significantly enhanced, but tumor necrosis factor alpha, NFKB1 (p50 and its precursor, p105), neurotrophin-3, Bcl-2-associated X protein, calpain, caspase 12, caspase 9, and caspase 3 were significantly suppressed in DOX-treated mice under oral treatment with the herbal formula B307.

CONCLUSION

Our results revealed that oral treatment with the herbal formula B307 may provide cardioprotection in DOX-treated mice via suppressing oxidative stress, inflammation, and apoptosis in heart tissue. We believe that the herbal formula B307 may be developed as a potential alternative treatment for cancer patients under DOX treatment.