Inhibition of neointima hyperplasia by the combined therapy of linagliptin and metformin via AMPK/Nox4 signaling in diabetic rats

Tilianin attenuates inflammasome activation in endothelial progenitor cells to mitigate myocardial ischemia-reperfusion injury

Tilianin (TIL), a bioactive component derived from Dracocephalum Moldavica L., has been recognized for its anti-inflammatory properties. However, its effects on the Nlrp3 inflammasome within endothelial progenitor cells (EPCs) during myocardial ischemia-reperfusion injury (MIRI) remain unexplored. This study aimed to elucidate the role of TIL in modulating Nlrp3 inflammasome activation under MIRI conditions. A mouse model of MIRI was established to assess the therapeutic potential of TIL. EPCs treated with TIL at concentrations of 5, 10, and 20 μM were administered into the myocardium before reperfusion. Additionally, the cardioprotective effects of TIL were further examined by pre-treating EPCs with the compound before exposing them to hypoxia/reoxygenation (H/R) using cardiomyocyte supernatants. The impact on Nlrp3 inflammasome was assessed through western blotting, immunofluorescence, and ELISA. Our results showed that TIL concentration-dependently inhibited Nlrp3 inflammasome-related protein levels,and inhibited Asc oligomerization and Asc-Speck complex formation in EPCs, resulting in improved the migratory capacity and vascular structure formation of EPCs. In addition, TIL-treated EPCs significantly attenuated I/R injury and improved cardiac function. These results suggest that TIL ameliorates the inflammatory response in EPCs by suppressing Nlrp3 inflammasome activation, thereby facilitating neovascularization in the myocardium and conferring protection against MIRI. The study provides valuable insights into the potential of TIL as a therapeutic agent for cardiovascular diseases linked to ischemia-reperfusion injury.

Simvastatin attenuates silica-induced pulmonary inflammation and fibrosis in rats via the AMPK-NOX pathway

BACKGROUND

Simvastatin (Sim), a hydroxy-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, has been widely used in prevention and treatment of cardiovascular diseases. Studies have suggested that Sim exerts anti-fibrotic effects by interfering fibroblast proliferation and collagen synthesis. This study was to determine whether Sim could alleviate silica-induced pulmonary fibrosis and explore the underlying mechanisms.

METHODS

The rat model of silicosis was established by the tracheal perfusion method and treated with Sim (5 or 10 mg/kg), AICAR (an AMPK agonist), and apocynin (a NOX inhibitor) for 28 days. Lung tissues were collected for further analyses including pathological histology, inflammatory response, oxidative stress, epithelial mesenchymal transformation (EMT), and the AMPK-NOX pathway.

RESULTS

Sim significantly reduced silica-induced pulmonary inflammation and fibrosis at 28 days after administration. Sim could reduce the levels of interleukin (IL)-1β, IL-6, tumor necrosis factor-α and transforming growth factor-β1 in lung tissues. The expressions of hydroxyproline, α-SMA and vimentin were down-regulated, while E-cad was increased in Sim-treated rats. In addition, NOX4, p22pox, p40phox, p-p47phox/p47phox expressions and ROS levels were all increased, whereas p-AMPK/AMPK was decreased in silica-induced rats. Sim or AICAR treatment could notably reverse the decrease of AMPK activity and increase of NOX activity induced by silica. Apocynin treatment exhibited similar protective effects to Sim, including down-regulating of oxidative stress and inhibition of the EMT process and inflammatory reactions.

CONCLUSIONS

Sim attenuates silica-induced pulmonary inflammation and fibrosis by downregulating EMT and oxidative stress through the AMPK-NOX pathway.

Empagliflozin ameliorates vascular calcification in diabetic mice through inhibiting Bhlhe40-dependent NLRP3 inflammasome activation

Type 2 diabetes mellitus (T2DM) patients exhibit greater susceptibility to vascular calcification (VC), which has a higher risk of death and disability. However, there is no specific drug for VC therapy. NLRP3 inflammasome activation as a hallmark event of medial calcification leads to arterial stiffness, causing vasoconstrictive dysfunction in T2DM. Empagliflozin (EMPA), a sodium-glucose co-transporter 2 inhibitor (SGLT2i), restrains hyperglycemia with definite cardiovascular benefits. Given the anti-inflammatory activity of EMPA, herein we investigated whether EMPA protected against VC in the aorta of T2DM mice by inhibiting NLRP3 inflammasome activation. Since db/db mice receiving a normal diet developed VC at the age of about 20 weeks, we administered EMPA (5, 10, 20 mg·kg-1·d-1, i.g) to 8 week-old db/db mice for 12 weeks. We showed that EMPA intervention dose-dependently ameliorated the calcium deposition, accompanied by reduced expression of RUNX2 and BMP2 proteins in the aortas. We found that EMPA (10 mg·kg-1·d-1 for 6 weeks) also protected against VC in vitamin D3-overloaded mice, suggesting the protective effects independent of metabolism. We showed that EMPA (10 mg·kg-1·d-1) inhibited the abnormal activation of NLRP3 inflammasome in aortic smooth muscle layer of db/db mice. Knockout (KO) of NLRP3 significantly alleviated VC in STZ-induced diabetic mice. The protective effects of EMPA were verified in high glucose (HG)-treated mouse aortic smooth muscle cells (MOVASs). In HG-treated NLRP3 KO MOVASs, EMPA (1 μM) did not cause further improvement. Bioinformatics and Western blot analysis revealed that EMPA significantly increased the expression levels of basic helix-loop-helix family transcription factor e40 (Bhlhe40) in HG-treated MOVASs, which served as a negative transcription factor directly binding to the promotor of Nlrp3. We conclude that EMPA ameliorates VC by inhibiting Bhlhe40-dpendent NLRP3 inflammasome activation. These results might provide potential significance for EMPA in VC therapy of T2DM patients.

Effects of advanced glycation end-products, diabetes and metformin on the osteoblastic transdifferentiation capacity of vascular smooth muscle cells: In vivo and in vitro studies

AIMS

Our objective was to study the vascular smooth muscle cells (VSMC) osteoblastic transdifferentiation in AGE exposed cells or those from diabetic animals, and its response to metformin treatment.

METHODS

VSMC were obtained from non-diabetic rats, grown with or without AGE; while VSMC of in vivo-ex vivo studies were obtained from non-diabetic control animals (C), diabetic (D), C treated with metformin (M) and D treated with metformin (D-M). We studied the osteoblastic differentiation by evaluating alkaline phosphatase (ALP), type I collagen (Col) and mineral deposit.

RESULTS

In vitro, AGE increased proliferation, migration, and osteoblastic differentiation of VSMC. Metformin cotreatment prevented the AGE induced proliferation and migration. Both AGE and metformin stimulated the expression of ALP and Col. AGE induced mineralization was prevented by metformin. VSMC from D expressed a higher production of Col and ALP. Those from D-M showed an ALP increase vs C and M, and a partial decrease vs D. Cultured in osteogenic medium, ALP, Col and mineralization increased in D vs C, remained unchanged in M, and were prevented in D-M animals.

CONCLUSION

Both AGE and DM favor VSMC differentiation towards the osteogenic phenotype and this effect can be prevented by metformin.

Evaluation of linagliptin and insulin combined therapy on unfolded protein response in type 1 diabetic mouse heart

The aim of this study is to reveal the effects of the use of linagliptin, a DPP-4 inhibitor due to its beneficial cardiovascular effects, on endoplasmic reticulum stress (ERS) signaling, which is involved in the pathogenesis of cardiovascular complications related to type 1 diabetes. BALB/c female mice (n = 72) were divided into six groups: control, diabetes+insulin, diabetes+linagliptin, diabetes+linagliptin+insulin, diabetes+TUDCA, and diabetes+TUDCA+insulin. Immunohistochemistry and western blot method, qRT-PCR, ELISA method, and malondialdehyde (MDA) measurements were performed. Linagliptin administered to the type 1 diabetic mouse heart significantly reduced the expression levels of the total and cleaved forms of ATF6, ATF4, and p-JNK, caspase 3. Immunohistochemical and western blot analyses revealed that cleaved caspase 3 protein expression was significantly increased in the diabetes+insulin group compared to the other groups. According to ELISA findings, TUDCA was more effective in reducing NOX 1 and MDA levels than linagliptin. While linagliptin decreased the Chop mRNA level, no change was observed in the Grp78 mRNA level. Our findings showed that there was not much difference between the administration of linagliptin alone or in combination with insulin. Our study reveals that linagliptin is an effective therapeutic agent on ERS and apoptotic UPR in type 1 diabetic hearts.

Nox4 as a novel therapeutic target for diabetic vascular complications

Diabetic vascular complications can affect both microvascular and macrovascular. Diabetic microvascular complications, such as diabetic nephropathy, diabetic retinopathy, diabetic neuropathy, and diabetic cardiomyopathy, are believed to be caused by oxidative stress. The Nox family of NADPH oxidases is a significant source of reactive oxygen species and plays a crucial role in regulating redox signaling, particularly in response to high glucose and diabetes mellitus. This review aims to provide an overview of the current knowledge about the role of Nox4 and its regulatory mechanisms in diabetic microangiopathies. Especially, the latest novel advances in the upregulation of Nox4 that aggravate various cell types within diabetic kidney disease will be highlighted. Interestingly, this review also presents the mechanisms by which Nox4 regulates diabetic microangiopathy from novel perspectives such as epigenetics. Besides, we emphasize Nox4 as a therapeutic target for treating microvascular complications of diabetes and summarize drugs, inhibitors, and dietary components targeting Nox4 as important therapeutic measures in preventing and treating diabetic microangiopathy. Additionally, this review also sums up the evidence related to Nox4 and diabetic macroangiopathy.

Amarogentin inhibits vascular smooth muscle cell proliferation and migration and attenuates neointimal hyperplasia via AMPK activation

OBJECTIVES

Recent studies validated the expression of extraoral bitter taste receptors and established the importance of regulatory functions that are associated with various cellular biological processes of these receptors. However, the importance of bitter taste receptors' activity in neointimal hyperplasia has not yet been recognized. The bitter taste receptors activator amarogentin (AMA) is known to regulate a variety of cellular signals, including AMP-activated protein kinase (AMPK), STAT3, Akt, ERK, and p53, which are associated with neointimal hyperplasia.

MATERIALS AND METHODS

The present study assessed the effects of AMA on neointimal hyperplasia and explored the potential underlying mechanisms.

RESULTS

No cytotoxic concentration of AMA significantly inhibited the proliferation and migration of VSMCs induced by serum (15 % FBS) and PDGF-BB. In addition, AMA significantly inhibited neointimal hyperplasia of the cultured great saphenous vein in vitro and ligated mouse left carotid arteries in vivo, while the inhibitory effect of AMA on the proliferation and migration of VSMCs was mediated via the activation of AMPK-dependent signaling, which could be blocked via AMPK inhibition.

CONCLUSION

The present study revealed that AMA inhibited the proliferation and migration of VSMCs and attenuated neointimal hyperplasia, both in ligated mice carotid artery and cultured saphenous vein, which was mediated via a mechanism that involved AMPK activation. Importantly, the study highlighted the potential of AMA to be explored as a new drug candidate for neointimal hyperplasia.

Repositioning Linagliptin for the Mitigation of Cadmium-Induced Testicular Dysfunction in Rats: Targeting HMGB1/TLR4/NLRP3 Axis and Autophagy

Cadmium, a ubiquitous environmental toxicant, disrupts testicular function and fertility. The dipeptidyl peptidase-4 inhibitor linagliptin has shown pronounced anti-inflammatory and anti-apoptotic features; however, its effects against cadmium-evoked testicular impairment have not been examined. Herein, the present study investigated targeting inflammation, apoptosis, and autophagy by linagliptin for potential modulation of cadmium-induced testicular dysfunction in rats. After 60 days of cadmium chloride administration (5 mg/kg/day, by gavage), testes, epididymis, and blood were collected for analysis. The present findings revealed that linagliptin improved the histopathological lesions, including spermatogenesis impairment and germ cell loss. Moreover, it improved sperm count/motility and serum testosterone. The favorable effects of linagliptin were mediated by curbing testicular inflammation seen by dampening of HMGB1/TLR4 pathway and associated lowering of nuclear NF-κBp65. In tandem, linagliptin suppressed the activation of NLRP3 inflammasome/caspase 1 axis with consequent lowering of the pro-inflammatory IL-1β and IL-18. Jointly, linagliptin attenuated testicular apoptotic responses seen by Bax downregulation, Bcl-2 upregulation, and suppressed caspase 3 activity. With respect to autophagy, linagliptin enhanced the testicular autophagy flux seen by lowered accumulation of p62 SQSTM1 alongside upregulation of Beclin 1. The observed autophagy stimulation was associated with elevated AMPK (Ser487) phosphorylation and lowered mTOR (Ser2448) phosphorylation, indicating AMPK/mTOR pathway activation. In conclusion, inhibition of testicular HMGB1/TLR4/NLRP3 pro-inflammatory axis and apoptosis alongside stimulation of autophagy were implicated in the favorable actions of linagliptin against cadmium-triggered testicular impairment.

NLRP3 inflammasome links vascular senescence to diabetic vascular lesions

Vascular senescence is inextricably linked to the onset and progression of cardiovascular diseases (CVDs), which are the main cause of mortality in people with Type 2 diabetes (T2DM). Previous studies have emphasized the importance of chronic aseptic inflammation in diabetic vasculopathy. Here, we found the abnormal activation of NLRP3 inflammasome in the aorta of both old and T2DM mice by immunofluorescence and Western Blot analysis. Histopathological and isometry tension analysis showed that the presence of T2DM triggered or aggravated the increase of vascular aging markers, as well as age-associated vascular impairment and vasomotor dysfunction, which were improved by NLRP3 deletion or inhibition. Differential expression of aortic genes links to senescence activation and vascular remodeling supports the favorable benefits of NLRP3^-/- during T2DM. In vitro results based on primary mice aortic endothelial cells (MAECs) and vascular smooth muscle cells (VSMCs) demonstrate that NLRP3 deficiency attenuated premature senescence and restored proliferation and migration capability under-stimulation, and partially ameliorated replicative senescence. These results provide an insight into the critical role of NLRP3 signaling in T2DM-induced vascular aging and loss of vascular homeostasis, and provide the possibility that targeting NLRP3 inflammasome might be a promising strategy to prevent diabetic vascular senescence and associated vascular lesions.

Platelet-derived microvesicles regulate vascular smooth muscle cell energy metabolism via PRKAA after intimal injury

Vascular intimal injury initiates various cardiovascular disease processes. Exposure to subendothelial collagen can cause platelet activation, leading to platelet-derived microvesicles (aPMVs) secretion. In addition, vascular smooth muscle cells (VSMCs) exposed to large amounts of aPMVs undergo abnormal energy metabolism, they proliferate excessively and migrate after the loss of endothelium, eventually contributing to neointimal hyperplasia. However, the roles of aPMVs in VSMC energy metabolism are still unknown. Carotid artery intimal injury model indicated platelets adhered to injured blood vessels. In vitro, p-Pka content was increased in aPMVs. aPMVs significantly changed VSMC glycolysis and oxidative phosphorylation, and promoted VSMC migration and proliferation by upregulating p-PRKAA/p-FoxO1. Compound C, an inhibitor of PRKAA, effectively reversed the cell function and energy metabolism triggered by aPMVs in vitro and neointimal formation in vivo. Our data show that aPMVs can affect VSMC energy metabolism through the Pka/PRKAA/FoxO1 signaling pathway and ultimately affect VSMC function, indicating that VSMC metabolic phenotype shifted by aPMVs can be considered a potential target for the inhibition of hyperplasia and providing a new perspective for regulating the abnormal activity of VSMCs after injury.

Tert-Butylhydroquinone alleviates insulin resistance and liver steatosis in diabetes

OBJECTIVES:

This work aimed to determine tert-Butylhydroquinone (TBHQ)'s effects on insulin resistance (IR) and liver steatosis in diabetic animals and to explore the underpinning mechanisms.

MATERIALS AND METHODS:

Male ApoE^-/-mice underwent streptozocin (STZ) administration while receiving a sucrose/fat-rich diet for type 2 diabetes mellitus (T2DM) establishment. This was followed by a 6-week TBHQ administration. Body weight, fasting (FBG) and postprandial (PBG) blood glucose amounts, and insulin concentrations were measured, and the oral glucose tolerance test (OGTT) was carried out. Hematoxylin and eosin (H and E) staining and immunoblot were carried out for assessing histology and protein amounts in the liver tissue samples. In addition, cultured HepG2 cells were administered HClO and insulin for IR induction, and immunoblot was carried out for protein evaluation. Finally, the cells were stained with the Hoechst dye for apoptosis evaluation.

RESULTS:

The model animals showed T2DM signs, and TBHQ decreased FBG, ameliorated glucose tolerance and reduced liver steatosis in these animals. In addition, TBHQ markedly upregulated AMPKα2, GLUT4 and GSK3 β, as well as phosphorylated PI3K and AKT in the liver of mice with T2DM. In agreement, TBHQ decreased HClO-and insulin-related IR in cells and suppressed apoptosis through AMPKα2/PI3K/AKT signaling.

CONCLUSIONS:

TBHQ alleviates IR and liver steatosis in a mouse model of T2DM likely through AMPKα2/PI3K/AKT signaling.

A Novel Resveratrol Analog Upregulates SIRT1 Expression and Ameliorates Neointima Formation

Neointima formation is a serious complication caused by mechanical trauma to the vessel. (R)-4,6-dimethoxy-3-(4-methoxy phenyl)-2,3-dihydro-1H-indanone [(R)-TML 104] is a synthesized analog of the natural product resveratrol sesquiterpenes (±)-isopaucifloral F. The present study aimed to investigate the effects and underlying mechanisms of (R)-TML104 on neointima formation. Our results showed that (R)-TML104 prevented neointima formation based on a carotid artery injury model in mice. Furthermore, (R)-TML104 inhibited platelet-derived growth factor-BB (PDGF-BB)-induced vascular smooth muscle cells (VSMC) phenotypic transformation, evidenced by increased α-smooth muscle actin, reduced VSMC proliferation, and migration. Simultaneously, (R)-TML104 upregulated sirtuin-1 (SIRT1) expression in VSMC. We further uncovered that SIRT1 expression is critical for the inhibitory effects of (R)-TML104 on PDGF-BB-induced VSMC phenotypic transformation in vitro and injury-induced neointima formation in vivo. Finally, (R)-TML104-upregulated SIRT1 inhibited PDGF-BB-induced VSMC phenotypic transformation by downregulating nicotinamide adenine dinucleotide phosphate oxidase 4 expression via decreasing nuclear factor-κB acetylation. Taken together, these results revealed that (R)-TML104 upregulates SIRT1 expression and ameliorates neointima formation. Therefore, the application of (R)-TML104 may constitute an effective strategy to ameliorate neointima formation.

Pathogenesis and Clinical Significance of In-Stent Restenosis in Patients with Diabetes

Diabetes mellitus (DM) is a strong risk factor for the development of cardiovascular diseases such as coronary heart disease, cerebrovascular disease, and peripheral arterial disease (PAD). In the population of people living with DM, PAD is characterised by multi-level atherosclerotic lesions as well as greater involvement of the arteries below the knee. DM is also a factor that significantly increases the risk of lower limb amputation. Percutaneous balloon angioplasty with or without stent implantation is an important method of the treatment for atherosclerotic cardiovascular diseases, but restenosis is a factor limiting its long-term effectiveness. The pathogenesis of atherosclerosis in the course of DM differs slightly from that in the general population. In the population of people living with DM, more attention is drawn to such factors as inflammation, endothelial dysfunction, platelet dysfunction, blood rheological properties, hypercoagulability, and additional factors stimulating vascular smooth muscle cell proliferation. DM is a risk factor for restenosis. The purpose of this paper is to provide a review of the literature and to present the most important information on the current state of knowledge on mechanisms and the clinical significance of restenosis and in-stent restenosis in patients with DM, especially in association with the endovascular treatment of PAD. The role of such processes as inflammation, neointimal hyperplasia and neoatherosclerosis, allergy, resistance to antimitotic drugs used for coating stents and balloons, genetic factors, and technical and mechanical factors are discussed. The information on restenosis collected in this publication may be helpful in planning further research in this field, which may contribute to the formulation of more and more precise recommendations for the clinical practice.

Protective effects of metformin against myocardial ischemia‑reperfusion injury via AMPK‑dependent suppression of NOX4

Numerous studies have demonstrated that metformin can reduce the incidence of myocardial infarction and improve the prognosis of patients. However, its specific mechanism has not been determined. Using a rat model of myocardial ischemia-reperfusion injury (MIRI), it was observed that metformin significantly reduced infarct size, and decreased the levels of plasma lactate dehydrogenase and creatine kinase-MB form. A TTC-Evans blue staining was used to detect the infarct size and MTT assay was used to evaluate the cell viability. TUNEL assay was performed to evaluate apoptosis. Furthermore, 4-hydroxynonenal was detected by immunohistochemical staining. mRNA expression levels were detected by reverse transcription-quantitative PCR; protein expression levels were detected by immunoblotting. When treated with metformin, the number of TUNEL-positive cells was significantly decreased. Reduced 4HNE immunoreactivity was observed in metformin-treated rats as determined via immunohistochemistry. Furthermore, NADPH oxidase 4 (NOX4) was downregulated by metformin at both the mRNA and protein levels, and adenosine 5′-monophosphate-activated protein kinase (AMPK) phosphorylation was increased by metformin. In a primary myocardial hypoxia-reoxygenation cell model, metformin increased the viability of cardiomyocytes and reduced the content of malondialdehyde. It was also found that metformin upregulated the phosphorylation of AMPK and decreased the expression of NOX4. Furthermore, pre-treatment with AMPK inhibitor compound-C could block the effect of metformin, indicated by increased NOX4 compared with metformin treatment alone. These results suggested that metformin was capable of reducing the oxidative stress injury induced by MIRI. In conclusion, the present study indicated that metformin activated AMPK to inhibit the expression of NOX4, leading to a decrease in myocardial oxidative damage and apoptosis, thus alleviating reperfusion injury.

Jujuboside B Inhibits Neointimal Hyperplasia and Prevents Vascular Smooth Muscle Cell Dedifferentiation, Proliferation, and Migration via Activation of AMPK/PPAR-γ Signaling

The uncontrolled proliferation and migration of vascular smooth muscle cells is a critical step in the pathological process of restenosis caused by vascular intimal hyperplasia. Jujuboside B (JB) is one of the main biologically active ingredients extracted from the seeds of Zizyphus jujuba (SZJ), which has the properties of anti-platelet aggregation and reducing vascular tension. However, its effects on restenosis after vascular intervention caused by VSMCs proliferation and migration remain still unknown. Herein, we present novel data showing that JB treatment could significantly reduce the neointimal hyperplasia of balloon-damaged blood vessels in Sprague-Dawley (SD) rats. In cultured VSMCs, JB pretreatment significantly reduced cell dedifferentiation, proliferation, and migration induced by platelet-derived growth factor-BB (PDGF-BB). JB attenuated autophagy and reactive oxygen species (ROS) production stimulated by PDGF-BB. Besides, JB promoted the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and the expression of peroxisome proliferator-activated receptor-γ (PPAR-γ). Notably, inhibition of AMPK and PPAR-γ partially reversed the ability of JB to resist the proliferation and migration of VSMCs. Taken as a whole, our findings reveal for the first time the anti-restenosis properties of JB in vivo and in vitro after the endovascular intervention. JB antagonizes PDGF-BB-induced phenotypic switch, proliferation, and migration of vascular smooth muscle cells partly through AMPK/PPAR-γ pathway. These results indicate that JB might be a promising clinical candidate drug against in-stent restenosis, which provides a reference for further research on the prevention and treatment of vascular-related diseases.

Light sheet fluorescence microscopy as a new method for unbiased three-dimensional analysis of vascular injury

AIMS

Assessment of preclinical models of vascular disease is paramount in the successful translation of novel treatments. The results of these models have traditionally relied on two-dimensional (2D) histological methodologies. Light sheet fluorescence microscopy (LSFM) is an imaging platform that allows for three-dimensional (3D) visualization of whole organs and tissues. In this study, we describe an improved methodological approach utilizing LSFM for imaging of preclinical vascular injury models while minimizing analysis bias.

METHODS AND RESULTS

The rat carotid artery segmental pressure-controlled balloon injury and mouse carotid artery ligation injury were performed. Arteries were harvested and processed for LSFM imaging and 3D analysis, as well as for 2D area histological analysis. Artery processing for LSFM imaging did not induce vessel shrinkage or expansion and was reversible by rehydrating the artery, allowing for subsequent sectioning and histological staining a posteriori. By generating a volumetric visualization along the length of the arteries, LSFM imaging provided different analysis modalities including volumetric, area, and radial parameters. Thus, LSFM-imaged arteries provided more precise measurements compared to classic histological analysis. Furthermore, LSFM provided additional information as compared to 2D analysis in demonstrating remodelling of the arterial media in regions of hyperplasia and periadventitial neovascularization around the ligated mouse artery.

CONCLUSION

LSFM provides a novel and robust 3D imaging platform for visualizing and quantifying arterial injury in preclinical models. When compared with classic histology, LSFM outperformed traditional methods in precision and quantitative capabilities. LSFM allows for more comprehensive quantitation as compared to traditional histological methodologies, while minimizing user bias associated with area analysis of alternating, 2D histological artery cross-sections.

Regulation of NLRP3 inflammasome by CD38 through cADPR-mediated Ca2+ release in vascular smooth muscle cells in diabetic mice

AIMS

NLR family pyrin domain containing 3 (NLRP3) inflammasome activation contributes to the development of diabetic cardiovascular complications. CD38 regulates vascular inflammation through cyclic ADP-ribose (cADPR)-mediated Ca²⁺ signaling in vascular smooth muscle cells (VSMCs). Ca²⁺ mobilization may modulate inflammasome activation by impacting mitochondrial function. However, it remains unclear whether CD38 regulates NLRP3 inflammasome activation in VSMCs through cADPR-dependent Ca²⁺ release under diabetic condition. Main methods and key findings: In VSMCs, we observed that high glucose (HG, 30 mM) enhanced CD38 protein expression and ADP ribosyl cyclase activity. Moreover, along with less abundance of NLRP3, apoptosis-associated speck-like protein containing CARD (ASC) and their colocalization, the expression of active caspase-1(p20) and IL-1β were significantly inhibited by CD38 gene deficiency with siRNA transfection in VSMCs. Further, CD38 regulated the release of intracellular cADPR-mediated Ca²⁺ and mitochondrial DNA (mtDNA) to the cytosol, which was associated with NLRP3 inflammasome activation and VSMCs proliferation and collagen I synthesis. Finally, we found that CD38 inhibitors, nicotinamide and telmisartan significantly improved the endothelium-independent contraction and vascular remodeling, which was also associated with the inhibition of NLRP3 inflammasome in the aorta media in the diabetic mice.

SIGNIFICANCE

Our data suggested that CD38/cADPR-mediated Ca²⁺ signaling contributed to the mitochondrial damage, consequently released mtDNA to the cytosol, which was related with NLRP3 inflammasome activation and VSMCs remodeling in diabetic mice.

MicroRNA‑24 attenuates diabetic vascular remodeling by suppressing the NLRP3/caspase‑1/IL‑1β signaling pathway

Vascular remodeling plays an important role in the pathogenesis of diabetic cardiovascular complications. Previous published research has indicated that microRNA-24 (miR-24) is involved in diabetic vascular remodeling, but the underlying molecular mechanisms have yet to be fully elucidated. The aim of the present study was to investigate whether adenovirus-mediated miR-24 overexpression can suppress the NOD-like receptor family pyrin domain-containing 3 (NLRP3)-related inflammatory signaling pathway and attenuate diabetic vascular remodeling. The carotid arteries of diabetic rats were harvested and prepared for analysis. Reverse transcription-quantitative PCR and western blotting assays were used to detect the expressions of related mRNAs and proteins. Morphological examinations, including hematoxylin and eosin, immunohistochemical and Masson’s trichrome staining, were also performed. The results of the present study demonstrated that miR-24 upregulation suppressed neointimal hyperplasia and accelerated reendothelialization in the injured arteries, lowered the expression of NLRP3, apoptosis-associated speck-like protein, caspase-1, proliferating cell nuclear antigen, CD45, interleukin (IL)-1β, IL-18 and tumor necrosis factor-α, and increased the expression of CD31, smooth muscle (SM) α-actin and SM-myosin heavy chain. These data indicated that miR-24 overexpression can attenuate vascular remodeling in a diabetic rat model through suppressing the NLRP3/caspase-1/IL-1β signaling pathway.

Swimming Exercise Protects against Insulin Resistance via Regulating Oxidative Stress through Nox4 and AKT Signaling in High-Fat Diet-Fed Mice

Nonpharmaceutical therapies such as exercise training and diet intervention are widely used for the treatment of insulin resistance (IR). Although the skeletal muscle is the major peripheral tissue of glucose metabolism under insulin stimulation, the mechanism underlying muscle IR is poorly understood. Using a high-fat diet-induced IR mouse model, we here show that NADPH oxidase 4 (Nox4) upregulation mediates the production of reactive oxygen species (ROS) that causes metabolic syndrome featuring IR. The Nox4 expression level was markedly elevated in IR mice, and Nox4 overexpression was sufficient to trigger IR. Conversely, downregulation of Nox4 expression through exercise training prevented diet-induced IR by reducing the production of ROS and enhancing the AKT signaling pathway. Thus, this study indicates that exercise might improve IR through a reduction of Nox4-induced ROS in the skeletal muscle and enhancement of AKT signal transduction.