Salusin-β Is Involved in Diabetes Mellitus-Induced Endothelial Dysfunction via Degradation of Peroxisome Proliferator-Activated Receptor Gamma

Complement Factor C1q Mediates Vascular Endothelial Dysfunction in STZ-Induced Diabetic Mice

Diabetes is a significant global public health issue with implications for vascular endothelial cells (ECs) dysfunction and the subsequent development and advancement of diabetes complications. This study aims to compare the cellular and molecular properties of the aorta in normal and streptozotocin (STZ)-induced diabetic mice, with a focus on elucidating potential mechanism underlying EC dysfunction. Here, we performed a single-cell RNA sequencing survey of 32,573 cells from the aorta of normal and STZ-induced diabetic mice. We found a compendium of 10 distinct cell types, mainly ECs, smooth muscle cells, fibroblast, pericyte, immune cells, and stromal cells. As the diabetes condition progressed, we observed a subpopulation of aortic ECs that exhibited significantly elevated expression of complement (C) molecule C1qa compared with their healthy counterparts. This increased expression of C1qa was found to induce reactive oxygen species (ROS) production, facilitate EC migration and increased permeability, and impair the vasodilation within the aortic segment of mice. Furthermore, AAV-Tie2-shRNA-C1qa was administered into diabetic mice by tail vein injection, showing that inhibition of C1qa in the endothelium led to a reduction in ROS production, decreased vascular permeability, and improved vasodilation. Collectively, these findings highlight the crucial involvement of C1qa in endothelial dysfunction associated with diabetes.

ARTICLE HIGHLIGHTS

Serum salusin-α and -β levels in patients with parkinson's disease

BACKGROUND

The etiology of Parkinson's disease (PD) is not well known and there is increasing evidence that oxidative stress also plays an important role in its pathogenesis. Salusins alpha (salusin-α) and beta (salusin-β) affect the central nervous system, vasculature, and kidneys to increase the inflammatory response in endothelial cells, stimulate oxidative stress, and increase monocyte-endothelial adhesion. Neuroinflammation and oxidative stress play roles in the etiopathogenesis of PD.

PURPOSE

To investigate whether salusin-α and -β are related to PD and whether they are correlated with the development of atherosclerosis, body mass index, disease duration, and the Parkinson's Hoehn and Yahr stage.

RESULTS

The low-density lipoprotein cholesterol (LDL-C), total cholesterol, and salusin-β levels were significantly lower and age was significantly higher in Parkinson patients compared to healthy controls (ρ < 0.005). We found a negative linear correlation between salusin-β and the Hoehn and Yahr stage (ρ < 0.001, r = -0.515) in the patients.

CONCLUSIONS

There was a relationship between salusin-β and PD and a correlation between the salusin-β levels and Parkinson's stage. A possible underlying disease mechanism is an increase in oxidative stress and decrease in neuroprotective effects due to low salusin-β levels. Therefore, the effects of salusin-β in treating Parkinson disease should be evaluated. Further studies are needed to understand the effects of salusin-β treatment on preventing or slowing the course of PD.

Chicoric acid ameliorates sepsis-induced cardiomyopathy via regulating macrophage metabolism reprogramming

BACKGROUND

Sepsis-related cardiac dysfunction is believed to be a primary cause of high morbidity and mortality. Metabolic reprogramming is closely linked to NLRP3 inflammasome activation and dysregulated glycolysis in activated macrophages, leading to inflammatory responses in septic cardiomyopathy. Succinate dehydrogenase (SDH) and succinate play critical roles in the progression of metabolic reprogramming in macrophages. Inhibition of SDH may be postulated as an effective strategy to attenuate macrophage activation and sepsis-induced cardiac injury.

PURPOSE

This investigation was designed to examine the role of potential compounds that target SDH in septic cardiomyopathy and the underlying mechanisms involved.

METHODS/RESULTS

From a small molecule pool containing about 179 phenolic compounds, we found that chicoric acid (CA) had the strongest ability to inhibit SDH activity in macrophages. Lipopolysaccharide (LPS) exposure stimulated SDH activity, succinate accumulation and superoxide anion production, promoted mitochondrial dysfunction, and induced the expression of hypoxia-inducible factor-1α (HIF-1α) in macrophages, while CA ameliorated these changes. CA pretreatment reduced glycolysis by elevating the NAD+/NADH ratio in activated macrophages. In addition, CA promoted the dissociation of K(lysine) acetyltransferase 2A (KAT2A) from α-tubulin, and thus reducing α-tubulin acetylation, a critical event in the assembly and activation of NLRP3 inflammasome. Overexpression of KAT2A neutralized the effects of CA, indicating that CA inactivated NLRP3 inflammasome in a specific manner that depended on KAT2A inhibition. Importantly, CA protected the heart against endotoxin insult and improved sepsis-induced cardiac mitochondrial structure and function disruption. Collectively, CA downregulated HIF-1α expression via SDH inactivation and glycolysis downregulation in macrophages, leading to NLRP3 inflammasome inactivation and the improvement of sepsis-induced myocardial injury.

CONCLUSION

These results highlight the therapeutic role of CA in the resolution of sepsis-induced cardiac inflammation.

Saluisn-β contributes to endothelial dysfunction in monocrotaline-induced pulmonary arterial hypertensive rats

BACKGROUND

The endothelial dysfunction and the consequent attenuated pulmonary vasodilatation are the major causes of elevated pulmonary arterial resistance and pressure in pulmonary arterial hypertension (PAH). Current study aimed to explore the effects of a TOR2A gene product, salusin-β, on endothelium-dependent vascular relaxation and the progression of PAH in monocrotaline (MCT)-induced PAH rats as well as the relevant signaling pathway.

METHODS

Acetylcholine (ACh)-induced dose-dependent relaxation was used to evaluate the endothelium-dependent vasodilatation function.

RESULTS

The salusin-β level in plasma and pulmonary artery (PA) in MCT-PAH rats were significantly increased, while the ACh-induced endothelium-dependent vasodilatation was attenuated. After salusin-β incubation or overexpression of salusin-β gene, the endothelium-dependent relaxation was further deteriorated, while anti-salusin-β IgG incubation or knockdown of salusin-β improved it in PAH rats. The superoxide anions scavenger NAC or the antioxidant apocynin inhibited the effect of salusin-β, while the SOD inhibitor DETC further enhanced it. The nitric oxide (NO) synthase inhibitor L-NAME almost blocked the effect of anti-salusin-β IgG. Silencing of salusin-β in PAH rats decreased right ventricular (RV) systolic pressure, RV hypertrophy index, NAD(P)H oxidase activity and ROS level, and increased the eNOS activity and NO level of PA. Overexpression of salusin-β played opposite roles.

CONCLUSIONS

The elevated saluisn-β level in PAH rats plays important roles in the reduction of endothelium-dependent vasodilatation and participates in the progression of PAH through stimulating NAD(P)H oxidase-ROS production and inhibiting eNOS-NO release.

A dual Keap1 and p47phox inhibitor Ginsenoside Rb1 ameliorates high glucose/ox-LDL-induced endothelial cell injury and atherosclerosis

Oxidative stress is a vital contributor to the development and progression of diabetes-accelerated atherosclerosis. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a well-known molecule that participates in cellular defense against oxidative stress. Utilizing luciferase reporter assay from 379 natural products, we reported here that Ginsenoside Rb1 played a dual role in inhibiting Kelch-like ECH-associated protein 1 (Keap1) and p47^phox luciferase reporter activities. In endothelial cells (ECs), Rb1 pretreatment enhanced cell viability, reduced oxidative stress, inflammation, endothelial-mesenchymal transition (EndMT), and apoptosis, as well as ameliorated mitochondrial quality following oxidized low-density lipoprotein (ox-LDL) plus high glucose (HG) challenge. Rb1 directly bound to Keap1 and promoted its ubiquitination and proteasomal degradation dependent on lysine residues (K108, K323, and K551) by recruiting the E3 ligase synovial apoptosis inhibitor 1 (SYVN1), leading to Nrf2 dissociation from Keap1, Nrf2 nuclear translocation, Nrf2/PGC-1α complex formation. We further identified that Rb1 could bind to p47^phox and reduce its phosphorylation and membrane translocation, thereby disrupting the assembly of the NOX2 complex. Importantly, Rb1-mediated preservation of cytoplasmic p47^phox stabilized and contributed to Nrf2 activation. Additionally, we revealed that Rb1 reduced aortic atherosclerotic plaque formation along with reductions in oxidative stress and inflammatory response in streptozotocin (STZ)-induced ApoE^-/- mice, but not in ApoE^-/- mice with deficiency of Nrf2 and PGC-1α. Collectively, we demonstrated that Rb1, which directly targeted Keap1 and p47^phox in ECs, may be an attractive candidate for the treatment of atherosclerosis in diabetes.

β-Amyrin ameliorates diabetic nephropathy in mice and regulates the miR-181b-5p/HMGB2 axis in high glucose-stimulated HK-2 cells

Diabetic nephropathy (DN) is a diabetic complication that can cause renal failure. β-amyrin has been identified to possess anti-diabetic property. This study was designed to evaluate the potential role of β-amyrin in DN and its underlying mechanism. Streptozotocin-induced diabetic mice were used as the in vivo model, and high glucose (HG)-stimulated human proximal tubular HK-2 cells were utilized as the in vitro model. Renal histological changes in mice were assessed by hematoxylin-eosin and periodic acid-Schiff staining. HK-2 cell viability and apoptosis were detected by Cell Counting Kit-8 assay and flow cytometry analysis, respectively. β-amyrin was found to ameliorate kidney injury in DN mice and suppressed inflammatory response as well as apoptosis of HG-stimulated HK-2 cells. miR-181-5p expression in murine renal tissues and HK-2 cells was detected by in situ hybridization (ISH) and fluorescence in situ hybridization (FISH). MiR-181b-5p, a previously identified target for diabetic kidney disease, was downregulated in renal tissues and HG stimulated HK-2 cells, and β-amyrin induced the upregulation of miR-181b-5p. Binding relationship between miR-181b-5p and high mobility group box 2 (HMGB2) was confirmed by luciferase reporter assay. MiR-181b-5p bound to 3' untranslated region of HMGB2 to suppress its expression. As shown by immunohistochemical staining and immunofluorescence staining, HMGB2 was upregulated in the in vivo and in vitro models of DN, and β-amyrin induced the downregulation of HMGB2. Moreover, HMGB2 overexpression neutralized the suppressive effects of miR-181b-5p elevation on the inflammatory response and apoptosis of HG-treated HK-2 cells. Overall, β-amyrin ameliorates DN in mice and suppresses inflammatory response and apoptosis of HG-stimulated HK-2 cells via the miR-181b-5p/HMGB2 axis.

Inhibition of endoplasmic reticulum stress combined with activation of angiotensin-converting enzyme 2: novel approach for the prevention of endothelial dysfunction in type 1 diabetic rats

Persistent hyperglycemia in type 1 diabetes triggers numerous signaling pathways, which may prove deleterious to the endothelium. As hyperglycemia damages the endothelial layer via multiple signaling pathways, including enhanced oxidative stress, downregulation of angiotensin-converting enzyme 2 signaling, and exacerbation of endoplasmic reticulum (ER) stress, it becomes difficult to prevent injury using monotherapy. Thus, the present study was conceived to evaluate the combined effect of ER stress inhibition along with angiotensin-converting enzyme 2 activation, two major contributors to hyperglycemia-induced endothelial dysfunction, in preventing endothelial dysfunction associated with type 1 diabetes. Streptozotocin-induced diabetic animals were treated with either diminazene aceturate (5 mg·kg-1 per day, p.o.) or tauroursodeoxycholic acid, sodium salt (200 mg·kg-1 per day i.p.), or both for 4 weeks. Endothelial dysfunction was evaluated using vasoreactivity assay, where acetylcholine-induced relaxation was assessed in phenylephrine pre-contracted rings. Combination therapy significantly improved vascular relaxation when compared with diabetic control as well as monotherapy. Restoration of nitrite levels along with prevention of collagen led to improved vasodilatation. Moreover, there was an overall reduction in aortic oxidative stress. We conclude that by simultaneously inhibiting ER stress and activating angiotensin-converting enzyme 2 deleterious effects of hyperglycemia on endothelium were significantly alleviated. This could serve as a novel strategy for the prevention of endothelial dysfunction.

PPARβ down-regulation is involved in high glucose-induced endothelial injury via acceleration of nitrative stress

Endothelial injury plays a vital role in vascular lesions from diabetes mellitus (DM). Therapeutic targets against endothelial damage may provide critical venues for the treatment of diabetic vascular diseases. Peroxisome proliferator-activated receptor β (PPARβ) is a crucial regulator in DM and its complications. However, the molecular signal mediating the roles of PPARβ in DM-induced endothelial dysfunction is not fully understood. The impaired endothelium-dependent relaxation and destruction of the endothelium structures appeared in high glucose incubated rat aortic rings. A high glucose level significantly decreased the expression of PPARβ and endothelial nitric oxide synthase (eNOS) at the mRNA and protein levels, and reduced the concentration of nitric oxide (NO), which occurred in parallel with an increase in the expression of inducible nitric oxide synthase (iNOS) and 3-nitrotyrosine. The effect of high glucose was inhibited by GW0742, a PPARβ agonist. Both GSK0660 (PPARβ antagonist) and NG-nitro-l-arginine-methyl ester (NOS inhibitor) could reverse the protective effects of GW0742. These results suggest that the activation of nitrative stress may, at least in part, mediate the down-regulation of PPARβ in high glucose-impaired endothelial function in rat aorta. PPARβ-nitrative stress may hold potential in treating vascular complications from DM.

Association Between Dermcidin, Salusin-α, Salusin-β Molecules and Diabetic Foot Infections

Dermcidin, salusin-α, and salusin-β are three recently discovered molecules that confer antimicrobial properties. The present study aims to investigate the association between dermcidin, salusin-α, and salusin-β in the etiopathology of patients with diabetic foot infection. The study included three groups: Group 1 - diabetic foot infection; Group 2 - diabetes without history of diabetic foot; and Group 3 - the control group. Plasma dermcidin, salusin-α, and salusin-β levels were compared across the groups. Median (Q1-Q3) values of plasma dermcidin levels in Groups 1, 2, and 3 were 3.45 (0.8-4.4), 5.2 (3.7-6.4), and 5.8 (3.1-10) ng/mL, respectively. Diabetic foot infection group had significantly lower plasma dermcidin levels compared to diabetes only group and control group (P = .000, ANOVA), whereas there was no statistically significant difference between the Group 2 and Group 3 (P = .163, ANOVA). Salusin-α and salusin-β levels were significantly higher in the Group 3 compared to the other groups. Based on our findings, diabetic foot infection group had significantly lower plasma dermcidin levels and salusin-α and salusin-β levels were significantly higher in the control group. These molecules (dermcidin specifically) can be researched as an adjuvant therapeutic agent in addition to conventional treatments in diabetic foot diabetic foot infections. Also, it can be searched this may prevent many complications including amputation.

Understanding the Stony Bridge between Osteoporosis and Vascular Calcification: Impact of the FGF23/Klotho axis

A relationship between osteoporosis (OP) and vascular calcification (VC) is now proposed. There are common mechanisms underlying the regulation of them. Fibroblast growth factor- (FGF-) 23 and Klotho are hormones associated with the metabolic axis of osteovascular metabolism. Most recently, it was suggested that the FGF23-klotho axis is associated with increasing incidence of fractures and is potentially involved in the progression of the aortic-brachial stiffness ratio. Herein, we discussed the potential role of the FGF23/Klotho axis in the pathophysiology of OP and VC. We want to provide an update review in order to allow a better understanding of the potential role of the FGF23/Klotho axis in comorbidity of OP and VC. We believe that a better understanding of the relationship between both entities can help in proposing new therapeutic targets for reducing the increasing prevalence of OP and VC in the aging population.

Downregulation of Salusin-β protects renal tubular epithelial cells against high glucose-induced inflammation, oxidative stress, apoptosis and lipid accumulation via suppressing miR-155-5p

Diabetic nephropathy (DN) is the main contributor to the excess mortality for patients suffering from diabetes. Here, C57BL/6 mice received 4 weeks of high-fat diet and intraperitoneal injection of STZ (100 mg/kg). Mice with random blood glucose level ≥16.7 mmol/L and positive urine protein were recognized as successful DN model. To construct an in vitro model, HK-2 cells were incubated with 30 mM glucose. RT-qPCR and western blot were employed to measure Salusin-β levels in kidney tissues of DN mice and HG-induced HK-2 cells. Meanwhile, RT-qPCR was performed to detect miR-155-5p level in kidney tissues of DN mice and HG-induced HK-2 cells. TNF-α, IL-6, IL-1β, ROS, SOD and CAT levels were assessed using commercial assay kits. Furthermore, apoptosis of HK-2 cells was assessed via flow cytometric analysis and TUNEL staining. In addition, intracellular lipid accumulation and total cholesterol levels were detected using Oil red O staining and TC ELISA kit. Herein, Salusin-β and miR-155-5p levels were distinctly upregulated in kidney tissues of DN mice and HG-induced HK-2 cells. Downregulation of Salusin-β reduced miR-155-5p expression. Salusin-β silencing dramatically relieved inflammatory and oxidative injury, suppressed apoptosis as well as lipid accumulation induced by HG in HK-2 cells. Besides, miR-155-5p elevation partially abrogated the alleviating effects Salusin-β silencing on HG-induced RTEC injury. In summary, downregulation of Salusin-β protected HK-2 cells against HG-induced inflammation, oxidative stress, apoptosis and ameliorated lipid accumulation through suppressing miR-155-5p, which indicated that Salusin-β could be a potential therapeutic drug for DN.

Knockdown of Salusin-β Improves Cardiovascular Function in Myocardial Infarction-Induced Chronic Heart Failure Rats

Salusin-β is a biologically active peptide with 20 amino acids that exerts several cardiovascular activity-regulating effects, such as regulating vascular endothelial function and the proliferation of vascular smooth muscle cells. However, the regulatory effects of salusin-β in myocardial infarction-induced chronic heart failure (CHF) are still unknown. The current study is aimed at investigating the effects of silencing salusin-β on endothelial function, cardiac function, vascular and myocardial remodeling, and its underlying signaling pathways in CHF rats induced by coronary artery ligation. CHF and sham-operated (Sham) rats were subjected to tail vein injection of adenoviral vectors encoding salusin-β shRNA or a control-shRNA. The coronary artery (CA), pulmonary artery (PA), and mesenteric artery (MA) were isolated from rats, and isometric tension measurements of arteries were performed. Compared with Sham rats, the plasma salusin-β, leptin and visfatin levels and the salusin-β protein expression levels of CA, PA, and MA were increased, while the acetylcholine- (ACh-) induced endothelium-dependent vascular relaxation of CA, PA, and MA was attenuated significantly in CHF rats and was improved significantly by salusin-β gene knockdown. Salusin-β knockdown also improved cardiac function and vascular and myocardial remodeling, increased endothelial nitric oxide synthase (eNOS) activity and nitric oxide (NO) levels, and decreased NAD(P)H oxidase activity, NOX-2 and NOX-4 expression, and reactive oxygen species (ROS) levels in arteries in CHF rats. The effects of salusin-β knockdown in CHF rats were attenuated significantly by pretreatment with the NOS inhibitor L-NAME. These results indicate that silencing salusin-β contributes to the improvement of endothelial function, cardiac function, and cardiovascular remodeling in CHF by inhibiting NAD(P)H oxidase-ROS generation and activating eNOS-NO production.

Salusin‑β participates in high glucose‑induced HK‑2 cell ferroptosis in a Nrf‑2‑dependent manner

Ferroptosis is critically involved in the pathophysiology of diabetic nephropathy (DN). As a bioactive peptide, salusin‑β is abundantly expressed in the kidneys. However, it is unclear whether salusin‑β participates in the pathologies of diabetic kidney damage by regulating ferroptosis. The present study found that high glucose (HG) treatment upregulated the protein expressions of salusin‑β in a dose‑ and time‑dependent manner. Genetic knockdown of salusin‑β retarded, whereas overexpression of salusin‑β aggravated, HG‑triggered iron overload, antioxidant capability reduction, massive reactive oxygen species production and lipid peroxidation in HK‑2 cells. Mechanistically, salusin‑β inactivated nuclear factor erythroid‑derived 2‑like 2 (Nrf‑2) signaling, thus contributing to HG‑induced ferroptosis‑related changes in HK‑2 cells. Notably, the protein expression of salusin‑β was upregulated by ferroptosis activators, such as erastin, RSL3, FIN56 and buthionine sulfoximine. Pretreatment with ferrostatin‑1 (a ferroptosis inhibitor) prevented the upregulated protein expression of salusin‑β in HK‑2 cells exposed to HG. Taken together, these results suggested that a positive feedback loop between salusin‑β and ferroptosis primes renal tubular cells for injury in diabetes.

Evaluation of salusin-α and salusin-β levels in patients with type 2 diabetes mellitus and determination of the impact of severity of hyperglycemia on salusin levels

AIMS

To investigate the usefulness of salusin-α and salusin-β as biomarkers in patients with type 2 diabetes mellitus (T2DM) and to determine whether diabetes severity and obesity have an effect on the salusin levels in diabetic patients.

METHODS

The study included a total of 90 patients, comprising 55 diagnosed with T2DM and 35 healthy volunteers with similar demographic characteristics. Salusins were assayed by a commercially available ELISA kit.

RESULTS

The salusin-β levels were found to be significantly higher in T2DM group compared to control group, while the salusin-α levels were lower (p < 0.05, for both). Furthermore, in patient group, Spearman analysis showed a statistically significant negative correlation between salusin-α and fasting glucose and glycated hemoglobin (HbA1c), whereas salusin-β had a statistically significant positive correlation with fasting glucose and HbA1c (p < 0.05, for both). When analyzed according to the HbA1c groups, the patients with HbA1c > 9% had significantly lower salusin-α and higher salusin-β levels levels compared to those with HbA1c < 9% (p < 0.05, for both). When examined according to body-mass-index groups, there was no significant difference in the salusin levels of the patient and control groups (p > 0.05).

CONCLUSION

We demonstrated that the serum salusin-α level was decreased whereas the salusin-β level was increased in patients with T2DM compared to healthy subjects, and this was more pronounced as T2DM-deteriorated. We also showed that obesity had no effect on salusin levels among diabetics. This study may provide a basis for the availability of salusin-targeted therapies, especially in uncontrolled T2DM.

Improvement of Vascular Function by Knockdown of Salusin-β in Hypertensive Rats via Nitric Oxide and Reactive Oxygen Species Signaling Pathway

Purpose

Salusin-β, a multifunctional vasoactive peptide, has a potentially important function in the pathological development of hypertension. However, the exact functional role of salusin-β and the underlying mechanism in this process are still not fully understood. The current study aimed to investigate the effects of silencing salusin-β on vascular function and vascular remodeling, as well as its signaling pathways in spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY).

Methods

Silencing salusin-β was performed by caudal vein injection of adenovirus expressing salusin-β short hairpin RNA (shRNA). Acetylcholine (ACh)-induced endothelium-dependent relaxation was used to evaluate vasodilator function, and high K⁺ solution-induced constriction was used to evaluate vasoconstriction function.

Results

Salusin-β levels in plasma and its protein expression in mesenteric artery (MA), coronary artery (CA), and pulmonary artery (PA) of SHR were higher than those in WKY. The salusin-β level and expression were decreased effectively by salusin-β shRNA. Knockdown of salusin-β decreased arterial blood pressure (ABP) and high K⁺ solution-induced vascular constrictions, and improved the endothelium-dependent relaxation and vascular remodeling in SHR. The improved effect of silencing salusin-β on ACh-induced relaxation in SHR was almost blocked by the nitric oxide synthase (NOS) inhibitor L-NAME. Compared to WKY, the endothelial NOS (eNOS) activity and level, and nitric oxide (NO) level were decreased, while NAD(P)H oxidase activity and reactive oxygen species (ROS) levels in MA, CA, and PA of SHR were increased, which were all redressed by salusin-β knockdown.

Conclusion

These results indicate that knockdown of salusin-β improves endothelium-dependent vascular relaxation and vascular remodeling and decreases ABP and vasoconstriction in SHR, which might be accomplished by increasing eNOS activation and NO release while inhibiting NAD(P)H oxidase derived-ROS generation. Scavenging salusin-β improves vascular function and then prevents the development and progression of vasculopathy of hypertension.

Protocatechualdehyde restores endothelial dysfunction in streptozotocin-induced diabetic rats

Background

The present study was conducted with the aim of clarifying the effects of protocatechualdehyde (PCA) on the endothelial function in streptozotocin (STZ)-induced diabetic rats.

Methods

Sprague Dawley (SD) rats were intraperitoneally injected with STZ (single dose of 60 mg/kg). Diabetic model rats were given PCA (25 mg/kg/day) via gavage feeding for 6 weeks. Vascular function was studied; superoxide anion and nitrotyrosine levels were assessed; and nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) oxidase as well as total superoxide dismutase (SOD) activity were detected. Protein expression of phosphorylated endothelial nitric oxide synthase (P-eNOS), total endothelial nitric oxide synthase (T-eNOS), p22^phox, p47^phox and Cu/Zn-SOD were measured by Western blot analysis.

Results

PCA treatment significantly ameliorated the impairment of acetylcholine- evoked endothelium-dependent relaxation, with no obvious effects observed on the blood glucose or body weight in the STZ-induced diabetic rats. Expression levels of aortic P-eNOS/T-eNOS and endothelial nitric oxide synthase (eNOS) activity were decreased in STZ-induced diabetic rats while they remained unchanged in PCA-treated rats. However, PCA treatment improved oxidative inactivation of nitric oxide (NO) and decreased the levels of superoxide anion and nitrotyrosine in the aorta of STZ-induced diabetic rats; these were achieved by reducing the level of nitrotyrosine and down-regulating p47^phox and p22^phox expression, as well as up-regulating Cu/Zn-SOD protein expression. Consistently, the effects observed were associated with a decrease in NADPH oxidase activity and an increase in total SOD activity.

Conclusions

Our results indicate that the administration of PCA may be protective against oxidative stress and may restore endothelial function by improving vascular NO oxidative inactivation in diabetic condition.

Fundamental Mechanisms of the Cell Death Caused by Nitrosative Stress

Nitrosative stress, as an important oxygen metabolism disorder, has been shown to be closely associated with cardiovascular diseases, such as myocardial ischemia/reperfusion injury, aortic aneurysm, heart failure, hypertension, and atherosclerosis. Nitrosative stress refers to the joint biochemical reactions of nitric oxide (NO) and superoxide (O₂ ^-) when an oxygen metabolism disorder occurs in the body. The peroxynitrite anion (ONOO^-) produced during this process can nitrate several biomolecules, such as proteins, lipids, and DNA, to generate 3-nitrotyrosine (3-NT), which further induces cell death. Among these, protein tyrosine nitration and polyunsaturated fatty acid nitration are the most studied types to date. Accordingly, an in-depth study of the relationship between nitrosative stress and cell death has important practical significance for revealing the pathogenesis and strategies for prevention and treatment of various diseases, particularly cardiovascular diseases. Here, we review the latest research progress on the mechanisms of nitrosative stress-mediated cell death, primarily involving several regulated cell death processes, including apoptosis, autophagy, ferroptosis, pyroptosis, NETosis, and parthanatos, highlighting nitrosative stress as a unique mechanism in cardiovascular diseases.

Serum salusin-β in relation to atherosclerosis and ventricular dysfunction in patients with type 2 diabetes mellitus

BACKGROUND AND AIMS

Salusin-β is a newly defined biomarker that plays a role in atherogenesis and in homeostasis. The study aimed to assess serum salusin-β level in relation to atherosclerosis and ventricular dysfunction in type 2 diabetes mellitus (T2DM) patients.

METHODS

Sixty T2DM patients and twenty-five age-matched healthy controls were included. Serum salusin-β was determined by ELISA. Echocardiography and carotid ultrasonography were carried out for all individuals.

RESULTS

Serum salusin-β level was significantly elevated in patients with T2DM than in controls (P < 0.001). It was positively correlated with obesity parameters, insulin resistance index (r = 0.280,P < 0.001), atherogenic dyslipidemia and with carotid intima media thickness (CIMT) (r = 0.411, P < 0.001). Echocardiographic findings showed a positive correlation between salusin-β and left ventricular hypertrophy (LVH) parameters and a negative correlation with left ventricular (LV) diastolic and systolic functions. Regression analysis showed that serum salusin-β level was a significant predictor of diastolic dysfunction.

CONCLUSION

Serum salusin-β may be associated with atherosclerosis and LV dysfunction in T2DM.

Chicoric acid attenuates hyperglycemia-induced endothelial dysfunction through AMPK-dependent inhibition of oxidative/nitrative stresses

BACKGROUND

Endothelial dysfunction is a driving force during the development and progression of cardiovascular complications in diabetes. Targeting endothelial injury may be an attractive avenue for the management of diabetic vascular disorders. Chicoric acid is reported to confer antioxidant and anti-inflammatory properties in various diseases including diabetes. However, the role and mechanism of chicoric acid in hyperglycemia-induced endothelial damage are not well understood.

METHODS

In the present study, human umbilical vein endothelial cells (HUVECs) were incubated with high glucose/high fat (HG + HF) to induce endothelial cell injury.

RESULTS

We found that exposure of HUVECs to HG + HF medium promoted the release of cytochrome c (cytc) from mitochondrion into the cytoplasm, stimulated the cleavage of caspase-3 and poly ADP-ribose-polymerase (PARP), then inducing cell apoptosis, the effects that were prevented by administration of chicoric acid. Besides, we found that chicoric acid diminished HG + HF-induced phosphorylation and degradation of IκBα, and subsequent p65 NFκB nuclear translocation, thereby contributing to its anti-inflammatory effects in HUVECs. We also confirmed that chicoric acid mitigated oxidative/nitrative stresses under HG + HF conditions. Studies aimed at exploring the underlying mechanisms found that chicoric acid activated the AMP-activated protein kinase (AMPK) signaling pathway to attenuate HG + HF-triggered injury in HUVECs as AMPK inhibitor Compound C or silencing of AMPKα1 abolished the beneficial effects of chicoric acid in HUVECs.

CONCLUSION

Collectively, chicoric acid is likely protected against diabetes-induced endothelial dysfunction by activation of the AMPK signaling pathway. Chicoric acid could be a novel candidate for the treatment of the diabetes-associated vascular endothelial injury.

Salusin-β Promotes Vascular Calcification via Nicotinamide Adenine Dinucleotide Phosphate/Reactive Oxygen Species-Mediated Klotho Downregulation

Aims: Vascular calcification (VC) is a hallmark feature of cardiovascular disease and a significant risk factor for morbidity and mortality. Salusin-β exerts cardiovascular regulating effects in hypertension, atherosclerosis, and diabetes. The present study was designed to examine the roles of salusin-β in the progression of VC and its downstream signaling mechanisms. Results: Salusin-β expression in both the aortas of VC rats induced by vitamin D3 and nicotine and vascular smooth muscle cells (VSMCs) incubated with calcifying media was increased. Salusin-β knockdown remarkably reduced VC, whereas overexpression of salusin-β exacerbated VC both in vitro and in vivo. Overexpression of salusin-β promoted the VSMC osteochondrogenic transition, decreased Klotho protein levels, enhanced Ras-related C3 botulinum toxin substrate 1 (Rac1) activity and the translocation of p47phox to the membrane, increased the expression of nicotinamide adenine dinucleotide phosphate [NAD(P)H] oxidase subunits and the production of reactive oxygen species (ROS) with or without calcifying media; however, salusin-β deficiency played the opposite roles. The calcification and downregulated Klotho protein levels induced by salusin-β were restored by ROS scavenger N-acetyl-l-cysteine, diphenyleneiodonium chloride [an inhibitor of flavin-containing enzyme, including NAD(P)H oxidase], or gene knockdown of NAD(P)H oxidase (NOX)-2, p22phox, or p47phox but were not affected by NOX-1 and NOX-4 knockdown. Klotho knockdown attenuated the protective effect of salusin-β deficiency on VSMC calcification. By contrast, exogenous Klotho ameliorated the development of VC and ROS generation induced by salusin-β overexpression. Innovation: Salusin-β is a critical modulator in VC. Conclusion: Salusin-β regulates VC through activation of NAD(P)H/ROS-mediated Klotho downregulation, suggesting that salusin-β may be a novel target for treatment of VC.

Salusin-β mediates tubular cell apoptosis in acute kidney injury: Involvement of the PKC/ROS signaling pathway

Salusin-β is abundantly expressed in many organs and tissues including heart, blood vessels, brain and kidneys. Recent studies have identified salusin-β as a bioactive peptide that contributes to various diseases, such as atherosclerosis, hypertension, diabetes and metabolic syndrome. However, the role of salusin-β in the pathogenesis of acute kidney injury (AKI) is largely unclear. In the present study, we investigated the roles of salusin-β in cisplatin or lipopolysaccharide (LPS)-induced renal injury. Herein, we found that salusin-β expression was upregulated in both renal tubular cells and kidney tissues induced by both cisplatin and LPS. In vitro, silencing of salusin-β diminished, whereas overexpression of salusin-β exaggerated the increased PKC phosphorylation, oxidative stress, histone γH2AX expression, p53 activation and apoptosis in either cisplatin or LPS-challenged renal tubular cells. More importantly, salusin-β overexpression-induced tubular cell apoptosis were abolished by using the PKC inhibitor Go 6976, reactive oxygen species (ROS) scavenger NAC, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor apocynin (Apo) or p53 inhibitor Pifithrin-α. In animals, blockade of salusin-β alleviated PKC phosphorylation, ROS accumulation, DNA damage, and p53 activation as well as renal dysfunction in mice after administration of cisplatin or LPS. Taken together, these results suggest that overexpressed salusin-β is deleterious in AKI by activation of the PKC/ROS signaling pathway, thereby priming renal tubular cells for apoptosis and death.

Stimulation of Na+/K+-ATPase with an Antibody against Its 4th Extracellular Region Attenuates Angiotensin II-Induced H9c2 Cardiomyocyte Hypertrophy via an AMPK/SIRT3/PPARγ Signaling Pathway

Activation of the renin-angiotensin system (RAS) contributes to the pathogenesis of cardiovascular diseases. Sodium potassium ATPase (NKA) expression and activity are often regulated by angiotensin II (Ang II). This study is aimed at investigating whether DR-Ab, an antibody against 4^th extracellular region of NKA, can protect Ang II-induced cardiomyocyte hypertrophy. Our results showed that Ang II treatment significantly reduced NKA activity and membrane expression. Pretreatment with DR-Ab preserved cell size in Ang II-induced cardiomyopathy by stabilizing the plasma membrane expression of NKA and restoring its activity. DR-Ab reduced intracellular ROS generation through inhibition of NADPH oxidase activity and protection of mitochondrial functions in Ang II-treated H9c2 cardiomyocytes. Pharmacological manipulation and Western blotting analysis demonstrated the cardioprotective effects were mediated by the activation of the AMPK/Sirt-3/PPARγ signaling pathway. Taken together, our results suggest that dysfunction of NKA is an important mechanism for Ang II-induced cardiomyopathy and DR-Ab may be a novel and promising therapeutic approach to treat cardiomyocyte hypertrophy.

Oxymatrine ameliorates diabetes-induced aortic endothelial dysfunction via the regulation of eNOS and NOX4

AIM

Oxymatrine (OMT) is the major quinolizidine alkaloid extracted from the root of Sophora flavescens Ait (the Chinese herb Kushen) and exhibits diverse pharmacological actions. In this study, we investigated the effects of OMT on diabetes-associated aortic endothelial dysfunction in a rat model of diabetes and its mechanisms.

METHODS

Male Sprague-Dawley rats were randomly divided into five groups: control, diabetic rats, diabetic rats treated with OMT (60, 120 mg/kg per day, by gavage), and diabetic rats treated with metformin (20 mg/kg per day, by gavage). The serum fasting blood glucose, insulin, total cholesterol, triglyceride, and nitric oxide (NO) levels were determined with commercial kits. Biochemical indices reflecting oxidative stress, such as malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) were analyzed with commercial kits. Mitochondrial reactive oxygen species 2',7'-dichlorofluorescein diacetate (DCFH-DA) was measured by fluorescence microscopy. Histological analyses were conducted to observe morphological changes. Western blot analysis was applied to detect the expression levels of eNOS and NOX4. Reverse transcription polymerase chain reaction was used to detect the expressions of eNOS and NOX4 messenger RNA (mRNA).

RESULTS

The diabetic rats exhibited markedly reduced body weight and increased plasma glucose levels. Moreover, the diabetic rats showed oxidative stress (significantly increased MDA and decreased SOD, CAT, GSH-Px, and serum NO levels). Hyperglycemia caused significant endothelial injury and dysfunction, including vasodilative and histologic changes in the diabetic rats. The expressions of phospho-eNOS protein and mRNA were significantly decreased, while the NOX4 protein expression was increased in the aortas of the diabetic rats. All of these diabetes-induced effects were reversed by OMT in the diabetic rats.

CONCLUSION

The OMT treatment ameliorates diabetic endothelial dysfunction through enhanced NO bioavailability by upregulating eNOS expression and downregulating expression of NOX4.