Vascular smooth muscle cell apoptosis is an early trigger for hypothyroid atherosclerosis

Diagnostic potential of TSH to HDL cholesterol ratio in vulnerable carotid plaque identification

Objective

This study aimed to investigate the predictive value of the thyroid-stimulating hormone to high-density lipoprotein cholesterol ratio (THR) in identifying specific vulnerable carotid artery plaques.

Methods

In this retrospective analysis, we included 76 patients with carotid plaques who met the criteria for admission to Zhejiang Hospital from July 2019 to June 2021. High-resolution magnetic resonance imaging (HRMRI) and the MRI-PlaqueView vascular plaque imaging diagnostic system were utilized to analyze carotid artery images for the identification of specific plaque components, including the lipid core (LC), fibrous cap (FC), and intraplaque hemorrhage (IPH), and recording of the area percentage of LC and IPH, as well as the thickness of FC. Patients were categorized into stable plaque and vulnerable plaque groups based on diagnostic criteria for vulnerable plaques derived from imaging. Plaques were categorized based on meeting one of the following consensus criteria for vulnerability: lipid core area over 40% of total plaque area, fibrous cap thickness less than 65 um, or the presence of intraplaque hemorrhage. Plaques meeting the above criteria were designated as the LC-associated vulnerable plaque group, the IPH-associated group, and the FC-associated group. Multivariate logistic regression was employed to analyze the factors influencing carotid vulnerable plaques and specific vulnerable plaque components. Receiver operating characteristic (ROC) curves were used to assess the predictive value of serological indices for vulnerable carotid plaques.

Results

We found that THR (OR = 1.976; 95% CI = 1.094-3.570; p = 0.024) and TSH (OR = 1.939, 95% CI = 1.122-3.350, p = 0.018) contributed to the formation of vulnerable carotid plaques. THR exhibited an area under the curve (AUC) of 0.704 (95% CI = 0.588-0.803) (p = 0.003), and the AUC for TSH was 0.681 (95% CI = 0.564-0.783) (p = 0.008). THR was identified as an independent predictor of LC-associated vulnerable plaques (OR = 2.117, 95% CI = 1.064-4.212, p = 0.033), yielding an AUC of 0.815. THR also demonstrated diagnostic efficacy for LC-associated vulnerable plaques.

Conclusion

This study substantiated that THR and TSH have predictive value for identifying vulnerable carotid plaques, with THR proving to be a more effective diagnostic indicator than TSH. THR also exhibited predictive value and specificity in the context of LC-associated vulnerable plaques. These findings suggest that THR may be a promising clinical indicator, outperforming TSH in detecting specific vulnerable carotid plaques.

Relationship between Thyroid Feedback Quantile-based Index and cardiovascular diseases in a population with normal thyroid function: Evidence from the National Health and Nutrition Examination Survey 2007-2012

BACKGROUND

Previous study has demonstrated a link between TFQI, indicating the central sensitivity of thyroid hormones, and conditions like obesity, diabetes, and metabolic syndrome.

HYPOTHESIS

Nevertheless, the potential relationship between TFQI and cardiovascular disease (CVD) in individuals with normal thyroid function has yet to be established.

METHODS

The present research is a retrospective cohort investigation that included a total of 6297 individuals who had normal function of the thyroid and no history of thyroid disorders. These participants were selected from National Health and Nutrition Examination Survey data set, covering the years 2007-2012. The calculation of TFQI was performed depending on FT4 and TSH. Given the complex survey design and sample weights, we used multivariate linear regression models and stratified analysis to evaluate TFQI's correlation with CVD.

RESULTS

Subjects with CVD had greater levels of TFQI than those with no CVD. After adjusting for other covariates, TFQI exhibited a positive association with CVD risk, and the OR was 1.706 (p = .005). In subgroup analyses that were stratified by sex and BMI, it was shown that female individuals who had CVD had greater levels of TFQI in comparison to female participants without CVD (p = .002). Furthermore, elevated levels of TFQI were consistently connected to a raised incidence of CVD in the BMI (>28 kg/m2) group after regulating for different covariates. Furthermore, correlation analysis showed an association between TFQI and metabolic biomarkers.

CONCLUSIONS

The levels of TFQI are strongly connected to the prevalence of CVD, indicating that energy metabolism may be related to the occurrence of CVD.

Free triiodothyronine to free thyroxine ratio as a marker of poor prognosis in euthyroid patients with acute coronary syndrome and diabetes after percutaneous coronary intervention

Objectives

In recent years, the free triiodothyronine/free thyroxine (FT3/FT4) ratio, a new comprehensive index for evaluating thyroid function, which could reflect thyroid function more stably and truly than serum thyroid hormone level, has been demonstrated to correlate with the risks of diabetes and cardiovascular disease in euthyroid adults. However, the correlation between thyroid hormone sensitivity and long-term prognosis in euthyroid patients with acute coronary syndrome (ACS) and diabetes after percutaneous coronary intervention (PCI) remains unclear.

Methods

A total of 1,786 euthyroid patients with ACS who successfully underwent PCI at Beijing Anzhen Hospital from August 2021 to April 2022 were included in our study, which was divided into three groups according to tertiles of thyroid hormone sensitivity index. Cox regression, Kaplan-Meier, and receiver operating characteristic analyses were applied to analyze the associations between the FT3/FT4 ratio with ACS and diabetes after PCI.

Results

Our analysis indicated that a lower level of FT3/FT4 ratio in euthyroid patients with acute coronary syndrome (ACS) and diabetes after PCI showed significantly higher incidences of major adverse cardiac and cerebrovascular events (MACCE) when compared with a higher level of FT3/FT4 ratio. After adjusting for other covariates, patients with a lower level of FT3/FT4 ratio were negatively associated with the risk of MACCE than those with a higher level of FT3/FT4 ratio (adjusted OR =1.61, 95% CI 1.05-2.47, P = 0.028). In subgroup analyses, individuals were stratified by age, sex, BMI, ACS type, hypertension, and dyslipidemia, showing that there were no significant interactions between the FT3/FT4 ratio and all subgroups for MACCE. In addition, the FT3/FT4 ratio performed better on ROC analyses for cardiac death prediction [area under the curve (AUC), 0.738].

Conclusion

A reduced level of FT3/FT4 ratio was a potential marker of poor prognosis in euthyroid patients with ACS and diabetes after PCI.

Cell death in atherosclerosis

A complex and evolutionary process that involves the buildup of lipids in the arterial wall and the invasion of inflammatory cells results in atherosclerosis. Cell death is a fundamental biological process that is essential to the growth and dynamic equilibrium of all living things. Serious cell damage can cause a number of metabolic processes to stop, cell structure to be destroyed, or other irreversible changes that result in cell death. It is important to note that studies have shown that the two types of programmed cell death, apoptosis and autophagy, influence the onset and progression of atherosclerosis by controlling these cells. This could serve as a foundation for the creation of fresh atherosclerosis prevention and treatment strategies. Therefore, in this review, we summarized the molecular mechanisms of cell death, including apoptosis, pyroptosis, autophagy, necroptosis, ferroptosis and necrosis, and discussed their effects on endothelial cells, vascular smooth muscle cells and macrophages in the process of atherosclerosis, so as to provide reference for the next step to reveal the mechanism of atherosclerosis.

Hypothyroidism increases angiotensinogen gene expression associated with vascular smooth muscle cells cholesterol metabolism dysfunction and aorta remodeling in Psammomys obesus

It has been previously shown that clinical cardiovascular manifestations can be caused by mild changes in thyroid function. However, the implication of angiotensinogen (Agt) and vascular smooth muscle cells (VSMCs) dysfunction in the pathophysiology of cardiovascular manifestations in hypothyroidism have not yet been investigated. We induced experimental hypothyroidism in Psammomys obesus by administering carbimazole for five months. At the end of the experiment, the animals were sacrificed and histopathological analysis was performed using Masson's trichrome staining of the aorta and thyroid gland. The expression of the Agt gene and the genes implicated in cholesterol metabolism regulation in the liver and VSMCs was determined by qRT-PCR. Histological observations revealed profound remodeling of the aorta structure in animals with hypothyroidism. In addition, Agt gene expression in the liver was significantly increased. In vitro study, showed that VSMCs from hypothyroid animals overexpressed 3-hydroxy-3-methylglutaryl coenzyme A reductase (Hmgcr) and Acyl CoA:cholesterol acyltransferase (Acat) 1, with failure to increase the efflux pathway genes (ATP-binding cassette subfamily G member (Abcg) 1 and 4). These results suggest that hypothyroidism leads to vascular alterations, including structural remodeling, VSMCs cholesterol metabolism dysfunction, and their switch to a synthetic phenotype, together with hepatic Agt gene overexpression.

ANRIL rs4977574 Gene Polymorphism in Women with Recurrent Pregnancy Loss

BACKGROUND

ANRIL rs4977574 gene polymorphism has been associated with arterial thrombosis and cardiovascular disease development. ANRIL rs4977574 gene polymorphism could also be associated with recurrent pregnancy loss (RPL) since there is increasing evidence in favor of a potential shared pathophysiological mechanism with cardiovascular disease, potentially through arterial thrombosis. This study's goal is to investigate the differences in ANRIL rs4977574 gene polymorphism between women with and without RPL, if any, as well as a potential association with the number of pregnancy losses.

METHODS

DNA was isolated from peripheral blood samples, and the sequence containing the polymorphism of interest was amplified with PCR. Results were visualized under UV light following electrophoresis in 3% agarose gel with ethidium bromide. ANRIL rs4977574 (A>G) prevalence was compared between 56 women with and 69 without RPL. Results were adjusted for women's age and BMI, while a stratified analysis was performed according to number of pregnancy losses.

RESULTS

Allele A was significantly more prevalent in the control group compared to RPL women [31 (44.9%) vs. 14 (25%), p = 0.021]. Although not reaching statistical significance, a gradually decreasing prevalence of allele A with an increasing number of pregnancy losses was observed [31 (44.9%) in control, eight (30.7%) with two, six (23.1%) with three, and 0 (0.0%) with four pregnancy losses, p = 0.078]. Results were also similar following adjustment.

CONCLUSIONS

This is the first study that demonstrates an association between RPL presence and ANRIL rs4977574 gene polymorphism (lower prevalence of allele A), while a difference according to the number of pregnancy losses cannot be excluded.

Endothelial METRNL determines circulating METRNL level and maintains endothelial function against atherosclerosis

METRNL is a recently identified secreted protein with emerging functions. This study is to find major cellular source of circulating METRNL and to determine METRNL novel function. Here, we show METRNL is abundant in human and mouse vascular endothelium and released by endothelial cells using endoplasmic reticulum-Golgi apparatus pathway. By creating endothelial cell-specific Metrnl knockout mice, combined with bone marrow transplantation to produce bone marrow-specific deletion of Metrnl, we demonstrate that most of circulating METRNL (approximately 75%) originates from the endothelial cells. Both endothelial and circulating METRNL decrease in atherosclerosis mice and patients. By generating endothelial cell-specific Metrnl knockout in apolipoprotein E-deficient mice, combined with bone marrow-specific deletion of Metrnl in apolipoprotein E-deficient mice, we further demonstrate that endothelial METRNL deficiency accelerates atherosclerosis. Mechanically, endothelial METRNL deficiency causes vascular endothelial dysfunction including vasodilation impairment via reducing eNOS phosphorylation at Ser1177 and inflammation activation via enhancing NFκB pathway, which promotes the susceptibility of atherosclerosis. Exogenous METRNL rescues METRNL deficiency induced endothelial dysfunction. These findings reveal that METRNL is a new endothelial substance not only determining the circulating METRNL level but also regulating endothelial function for vascular health and disease. METRNL is a therapeutic target against endothelial dysfunction and atherosclerosis.

Mammalian Sirtuins and Their Relevance in Vascular Calcification

Cardiovascular diseases are a group of diseases with high morbidity and mortality that affect millions of people each year. Vascular calcification (VC) is an active process that involves the mineral deposition of calcium-phosphate complexes. VC is closely related to cardiovascular diseases, such as hypertension, heart failure, and calcific aortic stenosis, and is a type of ectopic calcification that occurs in the vessel walls. The sirtuins (silent mating-type information regulation 2; SIRTs), are a family of histone deacetylases whose function relies on nicotinamide adenine dinucleotide (NAD+). They have non-negligible functions in the regulation of energy metabolism, senescence, apoptosis, and other biological processes. Sirtuins have important effects on bone homeostasis and VC processes that share many similarities with bone formation. Sirtuins have been confirmed to deacetylate a variety of target proteins related to the occurrence and development of VC, thereby affecting the process of VC and providing new possibilities for the prevention and treatment of cardiovascular diseases. To facilitate the understanding of vascular calcification and accelerate the development of cardiovascular drugs, we reviewed and summarized recent research progress on the relationship between different types of sirtuins and VC.

miR-222-5p promotes dysfunction of human vascular smooth muscle cells by targeting RB1

BACKGROUND

Coronary atherosclerosis (AS) is characterized by the formation of plaque in the vessel wall. The structural and functional changes of vascular smooth muscle cells (VSMCs) can promote plaque formation and induce plaque instability.

OBJECTIVE

To investigate the functions and mechanism of miR-222-5p in VSMCs under the treatment of oxidized low-density lipoprotein (ox-LDL).

METHODS

miR-222-5p expression in ox-LDL-treated VSMCs and the serum of Apolipoprotein E (ApoE) knockout mice was detected by reverse transcription quantitative polymerase chain reaction. The viability and migration of VSMCs were detected by Cell Counting Kit-8 and Transwell assays. Protein levels of proliferation and migration-related factors were evaluated by western blotting. Luciferase reporter assays were performed to explore the binding between miR-222-5p and retinoblastoma susceptibility protein (RB1) gene in VSMCs. ApoE-knockout mice were infected with the lentivirus inhibiting miR-222-5p expression to explore the effect of miR-222-5p on pathological changes. Hematoxylin and eosin (H&E) staining, trichrome staining, and Oil Red O staining were conducted to determine the necrotic core area and atherosclerotic lesion size in the ascending aorta of ApoE-knockout mice.

RESULTS

With the accumulation of ox-LDL concentration and treatment time, miR-222-5p expression was gradually upregulated in VSMCs. Similarly, miR-222-5p expression was increased in the serum of ApoE-knockout mice. miR-222-5p knockdown inhibited the proliferative and migratory abilities of ox-LDL-treated VSMCs, and the inhibitory effect on cellular behaviors was then significantly reversed by co-knockdown of RB1. RB1 is a downstream target gene of miR-222-5p, and miR-222-5p bound with 3'-untranslated region of RB1 in VSMCs. We further confirmed that miR-222-5p knockdown alleviated pathological changes and inhibited lipid deposition in the serum of ApoE-knockout mice in vivo.

CONCLUSION

miR-222-5p accelerates the dysfunction of VSMCs and promotes pathological changes and lipid deposition in ApoE-knockout mice by targeting RB1. The study may provide novel therapeutic targets for AS.

Recent Progress of Chronic Stress in the Development of Atherosclerosis

With the development of the times, cardiovascular diseases have become the biggest cause of death in the global aging society, causing a serious social burden. Atherosclerosis is a chronic inflammatory disease, which can occur in large and medium-sized blood vessels in the whole body. It takes atherosclerotic plaque as the typical pathological change and endothelial injury as the core pathophysiological mechanism. It is the pathological basis of coronary heart disease, peripheral artery disease, cerebrovascular disease, and other diseases. Recent studies have shown that chronic stress plays an important role in the occurrence and development of atherosclerosis, endothelial injury, lipid metabolism, and chronic inflammation. This process involves a large number of molecular targets. It is usually the cause of atherosclerotic cardiovascular and cerebrovascular diseases. If chronic stress factors exist for a long time, patients have genetic susceptibility, and the combination of environmental factors triggers the pathogenesis, which may eventually lead to complete blockage of the blood vessels, unstable rupture of plaques, and serious adverse cardiovascular events. This paper reviews the role of chronic stress in the occurrence and development of atherosclerosis, focusing on the pathophysiological mechanism.

Expression ratio of circular to linear ANRIL in hypertensive patients with coronary artery disease

Atherosclerotic lesions of the coronary arteries are still in charge of significant annual morbidity and mortality despite intense therapeutic advancements. Genome-born elements contribute substantially to the atherosclerosis process. ANRIL is one of the long non-coding RNAs with outstanding functions particularly regulation of genes involved in atherosclerosis development. In this study, we measured ANRIL expression (circular-, linear-, and circular/linear ratio) in hypertensive patients with coronary artery disease (CAD) compared with peers without CAD. Among hypertensive patients who were candidates of angiography, 25 subjects with CAD and the equal number without CAD were considered as the case and control groups, respectively. Different categories of data were recorded through a predefined questionnaire. Before angiography, blood samples were obtained. After RNA extraction and cDNA synthesis, quantitative PCR was performed using specific primers for circular and linear ANRIL. Age and gender were not different between the groups. Most of the parameters of the lipid profile besides creatinine and blood urea nitrogen were remarkably worse in the case group. Circular ANRIL was significantly lower in the case group while linear counterparts were significantly higher in this group. Circular/linear ratio was also significantly lower in the case group. To overcome growing devastating trend of CAD, scrutinizing different factors involved in the initiation and development of atherosclerosis is a must. Atheroprotective role of circular ANRIL and atheroprogressive role of linear ANRIL were shown in our patients with hypertension.

LncRNA SNHG16 accelerates atherosclerosis and promotes ox-LDL-induced VSMC growth via the miRNA-22-3p/HMGB2 axis

Long non-coding RNAs (LncRNAs) are essential regulators in the occurrence and development of AS. Here we aim to explore the underlying molecular mechanism of LncRNA SNHG16 in regulating ox-LDL-induced VSMC proliferation, migration and invasion. After constructing AS in vivo and in vitro models, the expressions of SNHG16, miR-22-3p, HMBG2, proliferation- and metastasis-related proteins were determined by qRT-PCR and Western blot assays. Detection of serological lipids, H&E and Masson staining analysis were conducted to evaluate the AS injury in mice. The effects of ox-LDL treatment on VSMCs were examined by CCK-8, wound scratch and Transwell Chamber assays. The targeted relationship was measured by luciferase reporter and RIP assays. The results showed that SNHG16 and high-mobility group box 2 (HMGB2) expressions were increased while miRNA-22-3p expression was decreased in AS mice and ox-LDL-stimulated VSMCs. Functionally, sh-SNHG16 restrained ox-LDL-induced VSMC growth and migration. SNHG16 suppressed miRNA-22-3p expression by direct binding. Furthermore, in ox-LDL-treated VSMCs, miRNA-22-3p mimic prevented proliferation, migration, and invasion. Further explorations showed that HMGB2 was a target of miRNA-22-3p, SNHG16 upregulated HMGB2 levels by acting as a competing endogenous RNA (ceRNA) of miRNA-22-3p. More importantly, sh-HMGB2 partially reversed the effects of sh-SNHG16 together with miR-22-2p inhibitor on ox-LDL-induced VSMC proliferation, migration and invasion. Collectively, SNHG16 accelerated atherosclerotic plaque (AP) formation and enhanced ox-LDL-activated VSMCs proliferation and migration by miRNA-22-3p/HMGB2 axis.

Thyroid hormones inhibit apoptosis of macrophage induced by oxidized low-density lipoprotein

Increasing evidence suggests that hypothyroidism aggravates atherosclerosis. Macrophage apoptosis plays a significant role in the development of atherosclerotic plaque. We aimed to explore the effect of thyroid hormones on macrophage apoptosis induced by oxidized low-density lipoprotein (oxLDL). Peripheral blood samples from 20 patients (normal group, hypothyroidism group, coronary artery disease [CAD] group, hypothyroidism + CAD group) were collected to perform messenger RNA microarray analysis. Bioinformatics analysis identified apoptosis and mitogen-activated protein kinase (MAPK) signaling as differentially expressed pathways between CAD and hypothyroidism + CAD group. In vitro, thyroid hormones concentration-dependently promoted cell survival and inhibited apoptosis in oxLDL-treated RAW264.7 macrophages, along with elevated extracellular signal-regulated kinases 1 and 2 (Erk1/2) phosphorylation. The STRING database showed an interaction of thyroid hormone receptor alpha1 (TRα1) and MAPK pathway. TRα1 knockdown increased cell apoptosis and decreased Erk1/2 phosphorylation. Erk1/2 inhibitor aggravated macrophage apoptosis. Moreover, thyroid hormones inhibited oxidative stress in oxLDL-treated macrophages. The study indicates that thyroid hormones concentration-dependently attenuate oxLDL-induced macrophage apoptosis through activating TRα1-Erk1/2 pathway and inhibiting oxidative stress, which implies a potential mechanism of hypothyroid-accelerated atherosclerosis.

LncRNA APOA1-AS facilitates proliferation and migration and represses apoptosis of VSMCs through TAF15-mediated SMAD3 mRNA stabilization

Coronary atherosclerosis (CAS) is a major cause of cardiovascular disease. Long non-coding RNAs (lncRNAs) have been implicated as novel biomarkers in coronary artery disease (CAD). APOA1 antisense RNA (APOA1-AS) was proven to show high expression during atherosclerotic development, but no report has uncovered the detailed mechanism of APOA1-AS in CAS. Thus, this paper aims to explore the role of APOA1-AS in CAS. Vascular smooth muscle cells (VSMCs) were treated with oxidized low-density lipoprotein (ox-LDL) to mimic atherosclerosis-like injury. Quantitative real-time PCR (RT-qPCR) and western blot analysis analyzed gene expression. Cell counting kit-8 (CCK-8), wound healing assay, and flow cytometry were implemented to assess the function of APOA1-AS in modulating pathological phenotype of VSMCs. Results demonstrated that APOA1-AS was notably up-regulated in ox-LDL treated VSMCs (ox-LDL-VSMCs). The deficiency of APOA1-AS hindered proliferation and migration and stimulated apoptosis in ox-LDL-VSMCs. Mechanistically, APOA1-AS recruited TATA-box binding protein associated factor 15 (TAF15) protein to stabilized SMAD family member 3 (SMAD3) mRNA and activate the TGF-β/SMAD3 signaling pathway. In conclusion, APOA1-AS contributed to proliferation and migration and repressed apoptosis of VSMCs through TAF15-mediated SMAD3 mRNA stabilization, indicating that APOA1-AS could be a promising target for CAS.

Dual Role of Mitophagy in Cardiovascular Diseases

ABSTRACT

Mitophagy is involved in the development of various cardiovascular diseases, such as atherosclerosis, heart failure, myocardial ischemia/reperfusion injury, and hypertension. Mitophagy is essential for maintaining intracellular homeostasis and physiological function in most cardiovascular origin cells, such as cardiomyocytes, endothelial cells, and vascular smooth muscle cells. Mitophagy is crucial to ensuring energy supply by selectively removing dysfunctional mitochondria, maintaining a balance in the number of mitochondria in cells, ensuring the integrity of mitochondrial structure and function, maintaining homeostasis, and promoting cell survival. Substantial research has indicated a "dual" effect of mitophagy on cardiac function, with inadequate and increased mitochondrial degradation both likely to influence the progression of cardiovascular disease. This review summarizes the main regulatory pathways of mitophagy and emphasizes that an appropriate amount of mitophagy can prevent endothelial cell injury, vascular smooth muscle cell proliferation, macrophage polarization, and cardiomyocyte apoptosis, avoiding further progression of cardiovascular diseases.

Circular RNA PPP1CC promotes Porphyromonas gingivalis-lipopolysaccharide-induced pyroptosis of vascular smooth muscle cells by activating the HMGB1/TLR9/AIM2 pathway

Objective

Porphyromonas gingivalis (Pg) plays a critical role in the occurrence and development of atherosclerosis. Lipopolysaccharide from Pg (Pg-LPS) could lead to pyroptosis of vascular smooth muscle cells (VSMCs) and induce instability of atherosclerotic plaque. Therefore, pyroptosis of VSMCs could promote the process of atherosclerosis. However, the exact mechanism of Pg-LPS-induced pyroptosis of VSMCs is unclear.

Methods

We determined pyroptosis and expression of interleukin (IL)-1β and IL-18 in VSMCs using 4′,6-diamidino-2-phenylindole staining and ELISA after stimulation by Pg-LPS. We established a knockdown plasmid containing the circular (circ)RNA PPP1CC and transfected it into VSMCs. Luciferase assays were performed to reveal the association between microRNAs miR-103a-3p and miR-107 and circRNA PPP1CC.

Results

Stimulation of Pg-LPS led to pyroptosis of VSMCs. Knockdown of circRNA PPP1CC relieved the Pg-LPS-induced pyroptosis of VSMCs and suppressed the expression of HMGB1, TLR9, AIM2, and cleaved caspase-1. Luciferase assays showed that PPP1CC directly targeted and competitively adsorbed miR-103a-3p and miR-107, weakening the inhibitory effect of these microRNAs on the expression of HMGB1.

Conclusion

Knockdown of circRNA PPP1CC relieved Pg-LPS-induced pyroptosis of VSMCs. Pyroptosis of VSMCs appears to promote atherosclerosis and may represent a novel therapeutic target for its treatment.

CD146+Mesenchymal stem cells treatment improves vascularization, muscle contraction and VEGF expression, and reduces apoptosis in rat ischemic hind limb

Peripheral arterial disease (PAD) is an increasingly common narrowing of the peripheral arteries that can lead to lower limb ischemia, muscle weakness and gangrene. Surgical vein or arterial grafts could improve PAD, but may not be suitable in elderly patients, prompting research into less invasive approaches. Mesenchymal stem cells (MSCs) have been proposed as potential therapy, but their effectiveness and underlying mechanisms in limb ischemia are unclear. We tested the hypothesis that treatment with naive MSCs (nMSCs) or MSCs expressing CD146 (^CD146+MSCs) could improve vascularity and muscle function in rat model of hind-limb ischemia. Sixteen month old Sprague-Dawley rats were randomly assigned to 4 groups: sham-operated control, ischemia, ischemia + nMSCs and ischemia+^CD146+MSCs. After 4 weeks of respective treatment, rat groups were assessed for ischemic clinical score, Tarlov score, muscle capillary density, TUNEL apoptosis assay, contractile force, and vascular endothelial growth factor (VEGF) mRNA expression. ^CD146+MSCs showed greater CD146 mRNA expression than nMSCs. Treatment with nMSCs or ^CD146+MSCs improved clinical and Tarlov scores, muscle capillary density, contractile force and VEGF mRNA expression in ischemic limbs as compared to non-treated ischemia group. The improvements in muscle vascularity and function were particularly greater in ischemia+^CD146+MSCs than ischemia + nMSCs group. TUNEL positive apoptotic cells were least abundant in ischemia+^CD146+MSCs compared with ischemia + nMSCs and non-treated ischemia groups. Thus, MSCs particularly those expressing CD146 improve vascularity, muscle function and VEGF expression and reduce apoptosis in rat ischemic limb, and could represent a promising approach to improve angiogenesis and muscle function in PAD.

Long non-coding RNA NEAT1 regulates endothelial functions in subclinical hypothyroidism through miR-126/TRAF7 pathway

Subclinical hypothyroidism (SCH) is associated with increased risks of endothelial dysfunction and atherosclerosis, but the mechanisms remain unclear. In our previous study, microRNA-126-3p was downregulated in SCH, but the role and regulatory mechanism of miR-126 in SCH has not been investigated. A SCH mouse model was established by feeding mice methimazole. Both primary endothelial cells (ECs) and HUVECs were cultured. The expression levels of key molecules were detected via quantitative RT-PCR, western blotting, and immunofluorescence. Wire myography was used to analyze the changes in vascular tones. A dual-luciferase assay was used to investigate the relationship between lncRNAs, microRNAs and target genes. In detail, it was shown that the expression levels of miR-126-3p were significantly decreased in both the SCH vasculature and HUVECs. MiR-126 supplementation suppressed HUVEC apoptosis and improved vascular function. Moreover, miR-126 could bind to the 3'-untranslated region of TRAF7, thus, regulating the C-FLIP pathway and endothelial apoptosis. Furthermore, lncRNA NEAT1 was upregulated upon TSH treatment and could function as a ceRNA and bind to miR-126, thus, modulating its expression level and vascular function. Finally, the NEAT1/miR-126/TRAF7 axis functions in response to TSH and regulates endothelial functions in SCH in vitro and in vivo. In conclusion, dysregulation of the NEAT1/miR-126/TRAF7 axis is responsible for impaired endothelial functions in SCH. Targeting this axis might become a promising treatment strategy or improving endothelial functions in SCH.

Apoptosis, autophagy and atherosclerosis: Relationships and the role of Hsp27

Atherosclerosis is a multifactorial chronic inflammatory disease of the arterial wall, and an important pathological basis of coronary heart disease. Endothelial cells, vascular smooth muscle cells, and macrophages play important roles in the development of atherosclerosis. Of note, apoptosis and autophagy, two types of programmed cell death, influence the development and progression of atherosclerosis via the modulation of such cells. The small heat shock protein Hsp27 is a multifunctional protein induced by various stress factors and has a protective effect on cells. A large number of studies have demonstrated that Hsp27 plays an important role in regulating apoptosis. Recently, some studies have suggested that Hsp27 also participates in the autophagic process. Moreover, Hsp27 is closely related to the occurrence and development of atherosclerosis. Here, we summarize the molecular mechanisms of apoptosis and autophagy and discuss their effects on endothelial cells, vascular smooth muscle cells, and macrophages in the context of atherosclerotic procession. We further explore the involvement of Hsp27 in apoptosis, autophagy, and atherosclerosis. We speculate that Hsp27 may exert its anti-atherosclerotic role via the regulation of apoptosis and autophagy; this may provide the basis for the development of new approaches for the prevention and treatment of atherosclerosis.

Outcomes of Cardiac Resynchronization Therapy in Patients with Hypothyroidism and Heart Failure

Background

Hypothyroidism is known to be associated with adverse clinical outcomes in heart failure. The association between hypothyroidism and cardiac resynchronization therapy outcomes in patients with severe heart failure is not clear.

Methods

The study included 1316 patients who received cardiac resynchronization therapy between 2002 and 2015. Baseline demographics and cardiac resynchronization therapy outcomes, including left ventricular ejection fraction, New York Heart Association class, appropriate implantable cardioverter-defibrillator therapy, and all-cause mortality, were collected from the electronic health record.

Results

Of the study cohort, 350 patients (26.6%) were classified as the hypothyroidism group. The median duration of follow-up was 3.6 years (interquartile range, 1.7–6.2 years). Hypothyroidism was not associated with a higher risk of all-cause mortality in patients receiving CRT for heart failure. The risk of appropriate implantable cardioverter-defibrillator therapy significantly increased in association with increased baseline thyroid-stimulating hormone level in the entire cohort (hazard ratio, 1.23 per 5mIU/L increase; 95% CI, 1.01–1.5; P = 0.04) as well as in the hypothyroid group (hazard ratio, 1.44 per 5mIU/L increase; 95% CI, 1.13–1.84; P = 0.004).

Conclusions

CRT improves cardiac function in hypothyroid patients. The ventricular arrhythmic events requiring ICD therapies are associated with baseline TSH level, which might be considered as an important biomarker to stratify the risk of sudden death for patients with heart failure and hypothyroidism.

TAK1-AMPK Pathway in Macrophages Regulates Hypothyroid Atherosclerosis

PURPOSE

Hypothyroidism (HT) is associated with accelerated atherosclerosis (AS). The efficacy of traditional strategies of hypothyroid AS remains controversial. Here, we aimed to deepen the understanding of the HT-induced acceleration of AS, to decrease the residual risk of coronary artery disease (CAD) and to find a new therapeutic target.

METHODS

We collected peripheral venous blood samples from 20 patients and divided them into 4 groups, namely, the normal group, the HT group, the CAD group and the HT + CAD group. Then we performed mRNA microarray analysis and bioinformatics analysis to screen the differentially expressed genes and pathways, and we also conducted validations on ApoE knockout mice models and Raw264.7 cell models.

RESULTS

In short, (1) in the analysis between the CAD group and the HT + CAD group, we found a total of 1218 differentially expressed genes, 11 upregulated pathways and 40 downregulated pathways. (2) We validated that patients with HT and CAD had a significantly decreased expression of MAP3K7 (encoding transforming growth factor-β-activated kinase 1, TAK1) gene than normal subjects. (3) In animal and cell experiments, we found the decreased expression of TAK1 and the reduced phosphorylation of AMP-activated protein kinase (AMPK) under the hypothyroid and atherosclerotic condition. (4) Changes in the expressions of TAK1 may affect the progression of AS.

CONCLUSION

Taken together, these data suggest that the accelerated AS in hypothyroid patients may be due to the suppression of TAK1-AMPK pathway in macrophages. This new finding may become a novel therapeutic target in hypothyroid AS.

CTBP1‑AS2 inhibits proliferation and induces autophagy in ox‑LDL‑stimulated vascular smooth muscle cells by regulating miR‑195‑5p/ATG14

Atherosclerosis (AS) is a chronic progressive disease caused by injury and functional changes in vascular smooth muscle cells (VSMCs). Long non‑coding RNAs (lncRNAs) are pivotal regulators in AS development. The present study aimed to explore the roles and molecular mechanisms of lncRNA CTBP1‑AS2 in AS progression. A dual‑luciferase reporter assay confirmed that miR‑195‑5p is a downstream target miRNA of lncRNA CTBP1‑AS2 and miR‑195‑5p was increased in AS. The expression levels of miR‑195‑5p and CTBP1‑AS2 in the serums of patients with AS and human aorta vascular smooth muscle cells was increased or decreased, respectively, following treatment with oxidized low‑density lipoprotein (ox‑LDL). Functional experiments showed that the overexpression of lncRNA CTBP1‑AS2 inhibited the proliferation of HA‑VSMCs and promoted their autophagy following ox‑LDL treatment. This effect could be reversed by treatment with ROC‑325, the inhibitor of autophagy, or miR‑195‑5p mimics. Autophagy related 14 (ATG14) was identified to be a target of miR‑195‑5p, and lncRNA CTBP1‑AS2 promoted ATG14 expression by serving as a competing endogenous RNA of miR‑195‑5p. The present study revealed that lncRNA CTBP1‑AS2 may serve a role in AS by inhibiting the proliferation and promoting the autophagy of VSMCs through ATG14 modulation via miR‑195‑5p. These data may provide a novel therapeutic target for AS.

Acrolein-induced apoptosis of smooth muscle cells through NEAT1-Bmal1/Clock pathway and a protection from asparagus extract

Apoptosis of vascular smooth muscle cells (VSMCs) accelerates manifestation of plaque vulnerability in atherosclerosis. Long noncoding RNA NEAT1 participates in the proliferation and apoptosis of cells. In addition, circadian clock genes play a significant role in cell apoptosis. However, whether acrolein, an environmental pollutant, affects the apoptosis of VSMCs by regulating NEAT1 and clock genes is still elusive. We established VSMCs as an atherosclerotic cell model in vitro. Acrolein exposure reduced survival rate of VSMCs, and raised apoptosis percentage through upregulating the expression of Bax, Cytochrome c and Cleaved caspase-3 and downregulating Bcl-2. Asparagus extract (AE), as a dietary supplementation, was able to protect VSMCs against acrolein-induced apoptosis. Expression of NEAT1, Bmal1 and Clock was decreased by acrolein, while was ameliorated by AE. Knockdown of NEAT1, Bmal1 or Clock promoted VSMCs apoptosis by regulating Bax, Bcl-2, Cytochrome c and Caspase-3 levels. Correspondingly, overexpression of NEAT1 inhibited the apoptosis. We also observed that silence of NEAT1 repressed the expression of Bmal1/Clock and vice versa. In this study, we demonstrated that VSMCs apoptosis induced by acrolein was associated with downregulation of NEAT1 and Bmal1/Clock. AE alleviated the effects of proapoptotic response and circadian disorders caused by acrolein, which shed a new light on cardiovascular protection.

ANRIL and atherosclerosis

WHAT IS KNOWN AND OBJECTIVE

The 3.8-kb-long antisense non-coding RNA at the INK4 locus (ANRIL) is transcribed from the short arm of human chromosome 9 on P21 and is associated with malfunction of the vascular endothelium, vascular smooth muscle cell (VSMC) proliferation/migration/senescence/apoptosis, mononuclear cell adhesion and proliferation, glycolipid metabolism disorder and DNA damage. Hence, ANRIL plays an important role in atherogenesis. Moreover, genome-wide association studies (GWAS) have identified ANRIL as a biomarker that is closely related to coronary heart disease (CHD). The objective of this review was to discuss the pathological mechanism of ANRIL in atherosclerotic development and its significance as a predictor of cardiovascular disease.

METHODS

Review of the PubMed, EMBASE and Cochrane databases for articles demonstrating the roles of ANRIL in the development of atherosclerotic diseases.

RESULTS AND DISCUSSION

The abnormal expression of ANRIL is linked to vascular endothelium injury; the proliferation, migration, senescence and apoptosis of VSMCs; mononuclear cell adhesion and proliferation; glycolipid metabolism disorder; DNA damage; and competing endogenous RNAs. Moreover, ANRIL accelerates the progression of CHD by regulating its single nucleotide polymorphisms (SNPs).

WHAT IS NEW AND CONCLUSION

Considering that ANRIL accelerates atherosclerosis (AS) development and is a risk factor for CHD, it is reasonable for us to explore an efficacious ANRIL-based therapy for AS in CHD.

Role of microRNA-15a-5p in the atherosclerotic inflammatory response and arterial injury improvement of diabetic by targeting FASN

The present study aims to investigate the mechanism of miR-15a-5p in the atherosclerotic (AS) inflammatory response and arterial injury improvement in diabetic rats by regulating fatty acid synthase (FASN). Initially, bioinformatics tools were applied to evaluate miRNAs and genes correlating with AS, and the target relation between miRNAs and FASN was measured using the Dual-Luciferase Reporter Assay. Subsequently the diabetic AS rat model was established and the surviving rats were divided into: negative control (NC), miR-15a-5p mimic, miR-15a-5p inhibitor, sh-FASN and miR-15a-5p + sh-FASN groups. Then a series of experiments were performed to examine the degree of AS in each group. The results revealed that compared with the NC group, the expressions of C-reactive protein (CRP), interleukin 6 (IL-6), intercellular cell adhesion molecule-1 (ICAM1) in rat arterial tissue, as well as the levels of low-density lipoprotein cholesterol (LDL-C), blood glucose (BG), triglycerides (TG), total cholesterol (TC) and Homocysteine (Hcy) in rat serum, were increased after inhibiting miR-15a-5p, while the level of high-density lipoprotein cholesterol (HDL-C) was decreased and the fat storage area was enlarged after this treatment (P<0.05). In the miR-15a-5p mimic and sh-FASN groups, serum HDL-C levels were increased and the fat storage areas in arteries were reduced. The levels of CRP, IL-6, ICAM1 in rat arterial tissue, along with the levels of LDL-C, BG, TG, TC and Hcy in rat serum, were decreased (P<0.05). Hematoxylin and Eosin (HE) staining and transmission electron microscopy (TEM) results showed AS lesions to be apparent in the arteries of rats in both the NC and miR-15a-5p inhibitor groups, but that in miR-15a-5p and sh-FASN group were improved, the miR-15a-5p mimic + sh-FASN group showed the most obvious improvement. Taken together, miR-15a-5p alleviates the inflammation response and arterial injury in diabetic AS rats by targeting FASN.

Thyroid Function in Patients With a Fontan Circulation

In this study, we tested our hypothesis that thyroid function is impaired and contributes to perturbed hemodynamics in patients after Fontan operation. Cardiac catheterization and blood tests for thyroid function were performed in 37 patients who underwent a Fontan operation. Among them, 12 patients (33%) had subclinical thyroid dysfunction with an elevated thyroid-stimulating hormone level despite normal thyroxine levels. Thyroid-stimulating hormone levels were significantly correlated with central venous pressure (p <0.01, R² = 0.3), and patients with subclinical hypothyroidism showed significantly elevated γ-glutamyltransferase level, an indicator of liver congestion, compared with the other patients (125.6 ± 12.2 vs 67.6 ± 4.6 IU/L, p <0.01). In addition, the levels of free triiodothyronine, an effective thyroid hormone, were significantly lower in patients with subclinical hypothyroidism than in those with normal thyroid function (3.1 ± 0.1 vs 3.5 ± 0.1 pg/dl, p <0.01). The free triiodothyronine level was significantly and negatively correlated with the relaxation time constant (p = 0.03) and brain natriuretic hormone (p <0.01) level and positively correlated with the cardiac index (p = 0.04). In conclusion, venous congestion in Fontan patients may cause thyroid dysfunction, which can be responsible for decreased ventricular function and cardiac output in Fontan patients. Thus, thyroid function should be routinely monitored after Fontan surgery.

MicroRNA-25 Protects Smooth Muscle Cells against Corticosterone-Induced Apoptosis

Background and Aims

Vascular smooth muscle cells (VSMCs) are central components of atherosclerotic plaque. Loss of VSMCs through apoptotic cell death can cause fibrous cap thinning, necrotic core formation, and calcification that may destabilize plaque. Elevated glucocorticoid levels caused by psychological stress promote VSMC apoptosis and can exacerbate atherosclerosis in mice and humans. Changes in the levels of antiapoptosis microRNA-25 (miR-25) have been linked with heart disease, inflammation, VSMC phenotype, oxidative stress, and apoptosis. Here, we investigated the pathways and mechanisms of glucocorticoid-induced apoptosis of mouse VSMCs and the protective role of miR-25.

Methods

Primary mouse VSMCs were cultured +/- corticosterone for 48 h. Apoptosis, ROS, apoptotic protein activities, miR-25, MOAP1, a miR-25 target, and p70S6 kinase were quantified at intervals. The roles of miR-25 were assessed by treating cells with lenti-pre-miR-25 and anti-miR-25.

Results

VSMC apoptosis, caspase-3 activity, and Bax were increased by corticosterone, and cell death was paralleled by marked loss of miR-25. Protection was conferred by pre-miR-25 and exacerbated by anti-miR-25. Pre-miR-25 conferred reduced expression of the proapoptotic protein MOAP1, and the protective effects of pre-miR-25 were abrogated by overexpressing MOAP1. The antiapoptotic effects of miR-25 were paralleled by inhibition of the p70S6K pathway, a convergence target for the survival signaling pathways, and protection by pre-miR-25 was abrogated by the p70S6k inhibitor rapamycin.

Conclusions

MicroRNA-25 blocks corticosterone-induced VSMC apoptosis by targeting MOAP1 and the p70S6k pathway. Therapeutic manipulation of miR-25 may reduce atherosclerosis and unstable plaque formation associated with chronic stress.

SIRT7 Regulates the Vascular Smooth Muscle Cells Proliferation and Migration via Wnt/β-Catenin Signaling Pathway

A huge amount of evidence indicates that sirtuin 7 (SIRT7), a key mediator of many cellular activities, plays a crucial role in the pathogenesis of various diseases. However, little is known about the role of SIRT7 in atherosclerosis. This study investigated the potential role of SIRT7 in regulating the proliferation and migration of human vascular smooth muscle cells (HAVSMCs) and its possible molecular mechanism. In this study, human vascular smooth muscle cells (HAVSMCs) were induced by oxidized low-density lipoprotein (ox-LDL) to establish atherosclerosis (AS) cell model. Immunofluorescence staining and Western blot were used to detect the level of α-SMA expression, which was a marker protein in AS. In addition, RT-qPCR and Western blot assay were applied for exploring the mRNA and protein expression levels of SIRT7, Wnt, β-catenin, and cyclin D1 after knockdown or overexpression of SIRT7. And, furthermore, Cell Counting Kit-8 assay, flow cytometry, and wound-healing assay were used to assess HAVSMCs proliferation, cell cycle, and migration. Dickkopf-1 (DKK-1), a secretory glycoprotein that can block Wnt/β-catenin pathway, was used in SIRT7 overexpression HAVSMCs; subsequently cells proliferation and migration were assessed by Cell Counting Kit-8 assay, flow cytometry analysis, and wound-healing assay. We found that knockdown of SIRT7 significantly promoted cell proliferation and migration, decreased the percentages of cells in the G1 and G2 phases, and increased those in the S phase and downregulated the protein expression levels of Wnt, β-catenin, and cyclin D1, while overexpression of SIRT7 had reverse results. After treatment with Wnt/beta-catenin pathway inhibitor DKK-1 in SIRT7 overexpression HAVSMCs, cell proliferation and migration were increased, respectively. In conclusion, SIRT7 inhibited HAVSMCs proliferation and migration via enhancing Wnt/β-catenin activation, which provided a novel therapeutic strategy for antiatherosclerosis.

Baicalin inhibits proliferation and promotes apoptosis of vascular smooth muscle cells by regulating the MEG3/p53 pathway following treatment with ox‑LDL

Atherosclerosis (AS) is a systemic disease associated with lipid metabolic disorders and abnormal proliferation of smooth muscle cells. Baicalin is a flavonoid compound isolated from the dry roots of Scutellaria baicalensis Georgi and exerts anti-proliferative effects in various types of cells. However, the effect of baicalin on AS remains unclear. In the present study, serum samples were collected from patients with AS and an in vitro model of AS was established using oxidized low-density lipoprotein (ox-LDL)-treated human aorta vascular smooth muscle cells (HA-VSMCs). The siRNA transfection and overexpression efficiency of endogenous maternally expressed gene 3 (MEG3) and the expression level of MEG3 were analyzed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The effects of alterations in expression levels of MEG3 were assessed by MTT assay, bromodeoxyuridine incorporation assay, 5-ethynyl-2′-deoxyuridine staining, wound healing assay, immunofluorescence and western blotting in HA-VSMCs. qPCR indicated that the expression of MEG3 was reduced in serum samples from patients with AS and ox-LDL-treated HA-VSMCs, compared with serum samples from healthy patients and untreated HA-VSMCs, respectively. Further experiments indicated that ox-LDL-induced decrease of MEG3 expression was reversed by treatment with baicalin in a concentration-dependent manner. Following treatment with ox-LDL, decreased expression of MEG3 promoted proliferation and migration, and suppressed apoptosis in HA-VSMCs. Furthermore, treatment with baicalin reversed these effects on proliferation and apoptosis in ox-LDL-treated HA-VSMCs. The current study indicated that downregulated expression of MEG3 increased cell cycle-associated protein expression. However, treatment with baicalin inhibited the expression of cell-cycle associated proteins in HA-VSMCs with MEG3 knockdown. In addition, baicalin activated the p53 signaling pathway and promoted the expression and transport of p53 from the cytoplasm to nucleus following MEG3 knockdown in ox-LDL-treated HA-VSMCs. Baicalin inhibited proliferation and promoted apoptosis by regulating the expression of MEG3/p53, indicating that baicalin may serve a role in AS by activating the MEG3/p53 signaling pathway. The present study suggested a potential mechanism underlying the protective role of baicalin in the in vitro model of AS, and these results may be used to develop novel therapeutic approaches for the affected patients.

Comparison of the Inhibitory Mechanisms of Diethyl Citrate, Sodium Citrate, and Phosphonoformic Acid on Calcification Induced by High Inorganic Phosphate Contents in Mouse Aortic Smooth Muscle Cells

OBJECTIVE

This study aimed to investigate the differences and inhibitory effects of diethyl citrate (Et2Cit), sodium citrate (Na3Cit), and phosphonoformic acid (PFA) on calcification induced by high inorganic phosphate (Pi) contents in mouse aortic smooth muscle cells (MOVAS) and to develop drugs that can induce anticoagulation and inhibit vascular calcification (VC).

METHODS

Alive and fixed MOVAS were assessed for 14 days in the presence of high Pi with increasing Et2Cit, Na3Cit, and PFA concentrations. Calcification on MOVAS was measured through Alizarin red staining and the deposited calcium amount; apoptosis was detected by annexin V staining; and cell transdifferentiation was examined by measuring smooth muscle lineage gene (α-SMA) expression and alkaline phosphatase activity.

RESULTS

Coincubation of MOVAS with Et2Cit, Na3Cit, and PFA significantly decreased Pi-induced VC in live MOVAS, and the apoptotic rate was reduced by low inhibitor concentrations. The 3 inhibitors could prevent the alkaline phosphatase activity induced by high Pi contents and increased the expression of α-smooth muscle actin genes. Thus, the transdifferentiation of MOVAS into osteoblast-like cells was blocked. Their inhibitory effects exhibited concentration dependence. The inhibitory effect of each inhibitor at the same concentration showed the following trend: PFA > Na3Cit > Et2Cit.

CONCLUSIONS

Et2Cit, Na3Cit, and PFA prevented the calcification of MOVAS and inhibited the osteochondrocytic conversion of vascular smooth muscle cells. Thus, Et2Cit and Na3Cit as anticoagulants may alleviate VC in clinical applications.

H19 knockdown suppresses proliferation and induces apoptosis by regulating miR-148b/WNT/β-catenin in ox-LDL -stimulated vascular smooth muscle cells

Background

Long non-coding RNAs (lncRNAs) have been identified as critical regulators in the development of atherosclerosis (AS). Here, we focused on discussing roles and molecular mechanisms of lncRNA H19 in vascular smooth muscle cells (VSMCs) progression.

Methods

RT-qPCR assay was used to detect the expression patterns of H19 and miR-148b in clinical samples and cells. Cell proliferative ability was evaluated by CCK-8 and colony formation assays. Cell apoptotic capacity was assessed by apoptotic cell percentage and the caspase-3 activity. Bioinformatics analysis, luciferase and RNA immunoprecipitation (RIP) assays were employed to demonstrate cell percentage and the relationship among H19, miR-148b and wnt family member 1 (WNT1). Western blot assay was performed to determine expressions of proliferating cell nuclear antigen (PCNA), ki-67, Bax, Bcl-2, WNT1, β-catenin, C-myc and E-cadherin.

Results

The level of H19 was increased and miR-148b expression was decreased in human AS patient serums and oxidized low-density lipoprotein (ox-LDL)-stimulated human aorta vascular smooth muscle cells (HA-VSMCs). H19 knockdown suppressed proliferation and promoted apoptosis in HA-VSMCs following the treatment of ox-LDL. H19 inhibited miR-148b expression by direct interaction. Moreover, miR-148b inhibitor could reverse the effects of H19 depletion on proliferation and apoptosis in ox-LDL-stimulated HA-VSMCs. Further mechanical explorations showed that WNT1 was a target of miR-148b and H19 acted as a competing endogenous RNA (ceRNA) of miR-148b to enhance WNT1 expression. Furthermore, miR-148 inhibitor exerted its pro-proliferation and anti-apoptosis effects through activating WNT/β-catenin signaling in ox-LDL-stimulated HA-VSMCs.

Conclusion

H19 facilitated proliferation and inhibited apoptosis through modulating WNT/β-catenin signaling pathway via miR-148b in ox-LDL-stimulated HA-VSMCs, implicating the potential values of H19 in AS therapy.

Nicotinic acetylcholine receptor α7 subunit improves energy homeostasis and inhibits inflammation in nonalcoholic fatty liver disease

OBJECTIVE

Nonalcoholic fatty liver disease (NAFLD) is one of the most common liver diseases worldwide; yet, the pathogenesis of the disorder is not completely understood. The nicotinic acetylcholine receptor α7 subunit (α7nAChR) plays an indispensable role in the vagus nerve-regulated cholinergic anti-inflammatory pathway.

METHODS

In the present study, we investigated the key role of α7nAChR in NAFLD development. Male wild-type (WT) and α7nAChR knockout (α7nAChR^-/-) mice were fed a normal chow or a high-fat diet (HFD) for 16weeks to induce NAFLD.

RESULTS

We found that both the mRNA and protein levels of α7nAChR in the liver tissue of NAFLD mice were significantly higher than those in mice fed normal chow. There were no differences in food intake, body weight, hepatic cholesterol and triglyceride contents, and insulin sensitivity between WT and α7nAChR^-/- mice under normal condition. When the WT and α7nAChR^-/- mice were challenged with HFD, the body weight of α7nAChR^-/- mice became higher than that of WT mice. The oxygen consumption and energy expenditure in HFD-fed α7nAChR^-/- mice were significantly lower than that in HFD-fed WT mice. The HFD-fed α7nAChR^-/- mice also showed more aggravated hepatic lipid accumulation, steatosis and oxidative stress than HFD-fed WT mice. Macrophage infiltration; mRNA levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-1β; and liver fibrosis were significantly accelerated in HFD-fed α7nAChR^-/- mice compared to that in HFD-fed WT mice. In addition, the bolus insulin injection-activated insulin signaling pathway, which was reflected by the phosphorylation of insulin receptor at Tyr1162/Tyr1163 site (p-IR^{Tyr1162/Tyr1163}), insulin receptor substrate-1 at Tyr612 site (p-IRS-1^Tyr612) and Akt at Ser473 (p-Akt^Ser473), was significantly compromised in liver tissues of HFD-fed α7nAChR^-/- mice relative to HFD-fed WT mice. Finally, pharmacologically activation of α7nAChR in HFD-fed mice, with a selective agonist PNU-282987, remarkably ameliorated the hepatic steatosis, inflammatory cell infiltration and fibrosis.

CONCLUSION

In conclusion, our results demonstrate that activation of α7nAChR improves energy homeostasis and inhibits inflammation in nonalcoholic fatty liver disease.

Pioglitazone Attenuates Atherosclerosis in Diabetic Mice by Inhibition of Receptor for Advanced Glycation End-Product (RAGE) Signaling

Background

Peroxisome proliferator-activated receptor-γ (PPAR-γ) exhibits anti-inflammatory and anti-diabetic properties, and is protective against cardiovascular diseases. This study aimed to determine the effects of a PPAR-γ agonist pioglitazone on atherogenesis in an ApoE knockout mouse (ApoE^−/−) diabetic mouse model and in a cultured vascular smooth muscle cells (VSMCs) model.

Material/Methods

Male ApoE^−/− mice were rendered diabetic by 5 daily intraperitoneal injections of streptozotocin. Pioglitazone (20 mg/kg/d) or PPAR-γ inhibitor GW9662 (1 mg/kg/d) were administered for 12 weeks. At the end of treatment, mice were killed and the aortae were isolated. Oil Red O staining was used to evaluate atherosclerotic plaque area. H&E staining was used to evaluate the number of complicated plaques. Western blotting and immunohistochemistry were used to determine the expression of advanced glycation end-products (RAGE) and PPAR-γ. The effects of pioglitazone and GW9662 on RAGE and PPAR-γ expression were examined in cultured primary mouse VSMCs in hyperglycemic conditions.

Results

Administration of pioglitazone in diabetic ApoE^−/− mice successfully reduced atherosclerotic plaque area and the number of complicated plaques. Moreover, pioglitazone inhibited RAGE and stimulated PPAR-γ protein expression in atherosclerotic plaques of diabetic ApoE^−/− mice. In cultured VSMCs upon high-glucose challenge, pioglitazone downregulated RAGE mRNA and protein expression. Blockade of PPAR-γ activity by GW9662 remarkably attenuated the inhibitory actions of pioglitazone on atherogenesis, both in diabetic ApoE^−/− mice and in cultured VSMCs, upon high-glucose challenge.

Conclusions

Pioglitazone has a therapeutic effect on atherosclerosis in diabetes, and inhibition of RAGE signaling plays a critical role in mediating the beneficial effects of pioglitazone.

NAD replenishment with nicotinamide mononucleotide protects blood-brain barrier integrity and attenuates delayed tissue plasminogen activator-induced haemorrhagic transformation after cerebral ischaemia

BACKGROUND AND PURPOSE

Tissue plasminogen activator (tPA) is the only approved pharmacological therapy for acute brain ischaemia; however, a major limitation of tPA is the haemorrhagic transformation that follows tPA treatment. Here, we determined whether nicotinamide mononucleotide (NMN), a key intermediate of nicotinamide adenine dinucleotide biosynthesis, affects tPA-induced haemorrhagic transformation.

EXPERIMENTAL APPROACH

Middle cerebral artery occlusion (MCAO) was achieved in CD1 mice by introducing a filament to the left MCA for 5 h. When the filament was removed for reperfusion, tPA was infused via the tail vein. A single dose of NMN was injected i.p. (300 mg·kg^-1 ). Mice were killed at 24 h post ischaemia, and their brains were evaluated for brain infarction, oedema, haemoglobin content, apoptosis, neuroinflammation, blood-brain barrier (BBB) permeability, the expression of tight junction proteins (TJPs) and the activity/expression of MMPs.

KEY RESULTS

In the mice infused with tPA at 5 h post ischaemia, there were significant increases in mortality, brain infarction, brain oedema, brain haemoglobin level, neural apoptosis, Iba-1 staining (microglia activation) and myeloperoxidase staining (neutrophil infiltration). All these tPA-induced alterations were significantly prevented by NMN administration. Mechanistically, the delayed tPA treatment increased BBB permeability by down-regulating TJPs, including claudin-1, occludin and zonula occludens-1, and enhancing the activities and protein expression of MMP9 and MMP2. Similarly, NMN administration partly blocked these tPA-induced molecular changes.

CONCLUSIONS AND IMPLICATIONS

Our results demonstrate that NMN ameliorates tPA-induced haemorrhagic transformation in brain ischaemia by maintaining the integrity of the BBB.

Cross-Talk Between PCSK9 and Damaged mtDNA in Vascular Smooth Muscle Cells: Role in Apoptosis

AIMS

The present study was designed to investigate a possible interaction between vascular smooth muscle cell (SMC)-derived proprotein convertase subtilisin/kexin type 9 (PCSK9) and mitochondrial DNA (mtDNA) damage.

RESULTS

Treatment of cultured SMCs with the proinflammatory stimulus lipopolysaccharide (LPS) stimulated PCSK9 release and induced mtDNA damage. PCSK9 inhibition by its siRNA reduced, and its enhancement increased, mtDNA damage. Induction of mitochondria-derived reactive oxygen species (mtROS) (by rotenone, thenoyltrifluoroacetone, or antimycin A) enhanced mtDNA damage as well as PCSK9 release, suggesting a role of mtROS in PCSK9-mtDNA damage interplay. Induction of mtDNA damage (with the autophagy inhibitor, 3-methyladenine, or DNase II inhibition) enhanced PCSK9 expression, and inhibition of mtDNA damage (with the autophagy inducer, rapamycin) reduced PCSK9 expression, indicating bidirectional interplay between PCSK9 and mtDNA damage. Other studies showed that p38 MAPK is involved in PCSK9-induced mtDNA damage, and mammalian target of rapamycin activation plays a role in mtDNA damage-induced PCSK9 release. Functional impact of PCSK9-mtDNA damage cross-talk was evident in the form of SMC apoptosis, which was enhanced in cells treated with recombinant human PCSK9, but inhibited in cells treated with PCSK9 siRNA. Last, LPS administration in wild-type mice resulted in simultaneous PCSK9 release and mtDNA damage, but mtDNA damage was minimal in PCSK9-null mice given LPS.

INNOVATION

Vascular SMC-derived PCSK9 induces mtDNA damage, and damaged mtDNA fragments stimulate PCSK9 release mediated, at least in part, by mtROS.

CONCLUSIONS

These observations suggest positive feedback interplay between SMC-derived PCSK9 and mtDNA damage in the proinflammatory milieu involving mtROS. This interaction results in cellular injury, characterized by apoptosis-a hallmark of atherosclerosis. Antioxid. Redox Signal. 25, 997-1008.

Enalapril protects against myocardial ischemia/reperfusion injury in a swine model of cardiac arrest and resuscitation

There is strong evidence to suggest that angiotensin-converting enzyme inhibitors (ACEIs) protect against local myocardial ischemia/reperfusion (I/R) injury. This study was designed to explore whether ACEIs exert cardioprotective effects in a swine model of cardiac arrest (CA) and resuscitation. Male pigs were randomly assigned to three groups: sham-operated group, saline treatment group and enalapril treatment group. Thirty minutes after drug infusion, the animals in the saline and enalapril groups were subjected to ventricular fibrillation (8 min) followed by cardiopulmonary resuscitation (up to 30 min). Cardiac function was monitored, and myocardial tissue and blood were collected for analysis. Enalapril pre-treatment did not improve cardiac function or the 6-h survival rate after CA and resuscitation; however, this intervention ameliorated myocardial ultrastructural damage, reduced the level of plasma cardiac troponin I and decreased myocardial apoptosis. Plasma angiotensin (Ang) II and Ang-(1–7) levels were enhanced in the model of CA and resuscitation. Enalapril reduced the plasma Ang II level at 4 and 6 h after the return of spontaneous circulation whereas enalapril did not affect the plasma Ang-(1–7) level. Enalapril pre-treatment decreased the myocardial mRNA and protein expression of angiotensin-converting enzyme (ACE). Enalapril treatment also reduced the myocardial ACE/ACE2 ratio, both at the mRNA and the protein level. Enalapril pre-treatment did not affect the upregulation of ACE2, Ang II type 1 receptor (AT1R) and MAS after CA and resuscitation. Taken together, these findings suggest that enalapril protects against ischemic injury through the attenuation of the ACE/Ang II/AT1R axis after CA and resuscitation in pigs. These results suggest the potential therapeutic value of ACEIs in patients with CA.

Hepatic NAD(+) deficiency as a therapeutic target for non-alcoholic fatty liver disease in ageing

BACKGROUND AND PURPOSE

Ageing is an important risk factor of non-alcoholic fatty liver disease (NAFLD). Here, we investigated whether the deficiency of nicotinamide adenine dinucleotide (NAD(+) ), a ubiquitous coenzyme, links ageing with NAFLD.

EXPERIMENTAL APPROACH

Hepatic concentrations of NAD(+) , protein levels of nicotinamide phosphoribosyltransferase (NAMPT) and several other critical enzymes regulating NAD(+) biosynthesis, were compared in middle-aged and aged mice or patients. The influences of NAD(+) decline on the steatosis and steatohepatitis were evaluated in wild-type and H247A dominant-negative, enzymically-inactive NAMPT transgenic mice (DN-NAMPT) given normal or high-fat diet (HFD).

KEY RESULTS

Hepatic NAD(+) level decreased in aged mice and humans. NAMPT-controlled NAD(+) salvage, but not de novo biosynthesis pathway, was compromised in liver of elderly mice and humans. Given normal chow, middle-age DN-NAMPT mice displayed systemic NAD(+) reduction and had moderate NAFLD phenotypes, including lipid accumulation, enhanced oxidative stress, triggered inflammation and impaired insulin sensitivity in liver. All these NAFLD phenotypes, especially release of pro-inflammatory factors, Kupffer cell accumulation, monocytes infiltration, NLRP3 inflammasome pathway and hepatic fibrosis (Masson's staining and α-SMA staining), deteriorated further under HFD challenge. Oral administration of nicotinamide riboside, a natural NAD(+) precursor, completely corrected these NAFLD phenotypes induced by NAD(+) deficiency alone or HFD, whereas adenovirus-mediated SIRT1 overexpression only partially rescued these phenotypes.

CONCLUSIONS AND IMPLICATIONS

These results provide the first evidence that ageing-associated NAD(+) deficiency is a critical risk factor for NAFLD, and suggest that supplementation with NAD(+) substrates may be a promising therapeutic strategy to prevent and treat NAFLD.

XBP1 splicing triggers miR-150 transfer from smooth muscle cells to endothelial cells via extracellular vesicles

The interaction between endothelial cells (ECs) and smooth muscle cells (SMCs) plays a critical role in the maintenance of vessel wall homeostasis. The X-box binding protein 1 (XBP1) plays an important role in EC and SMC cellular functions. However, whether XBP1 is involved in EC-SMC interaction remains unclear. In this study, In vivo experiments with hindlimb ischemia models revealed that XBP1 deficiency in SMCs significantly attenuated angiogenesis in ischemic tissues, therefore retarded the foot blood perfusion recovery. In vitro studies indicated that either overexpression of the spliced XBP1 or treatment with platelet derived growth factor-BB up-regulated miR-150 expression and secretion via extracellular vesicles (EVs). The XBP1 splicing-mediated up-regulation of miR-150 might be due to increased stability. The SMC-derived EVs could trigger EC migration, which was abolished by miR-150 knockdown in SMCs, suggesting miR-150 is responsible for SMC-stimulated EC migration. The SMC-derived miR-150-containing EVs or premiR-150 transfection increased vascular endothelial growth factor (VEGF)-A mRNA and secretion in ECs. Both inhibitors SU5416 and LY294002 attenuated EVs-induced EC migration. This study demonstrates that XBP1 splicing in SMCs can control EC migration via SMC derived EVs-mediated miR-150 transfer and miR-150-driven VEGF-A/VEGFR/PI3K/Akt pathway activation, thereby modulating the maintenance of vessel wall homeostasis.

Association between thyroid-stimulating hormone and blood pressure in adults: an 11-year longitudinal study

BACKGROUND

The results of longitudinal studies on the association between thyroid function and blood pressure (BP) are divided. This study aimed to investigate this association in cross-sectional and longitudinal settings in a nationwide, random sample representative of the Finnish adult population aged 30 and over.

METHODS

The study sample was randomly drawn from the population register. A total of 5655 participants were included in the baseline analyses and 3453 in the 11-year prospective analyses. The associations between baseline TSH and (i) BP and BP change over time; and (ii) prevalent and incident hypertension were assessed using linear and logistic models, adjusted for age, gender, smoking and body mass index.

RESULTS

A positive association (β ± standard error) was observed between TSH and diastolic (0·36 ± 0·12, P = 0·003) but not systolic BP (0·16 ± 0·21, P = 0·45) at baseline. TSH was negatively associated with 11-year BP change in men (systolic: -0·92 ± 0·41, P = 0·03; diastolic: -0·66 ± 0·26, P = 0·01) but not in women (P ≥ 0·09 for systolic and diastolic BP change). Participants in the highest TSH tertile within the TSH reference interval (0·4-3·4 mU/L), as compared with the lowest, had increased odds of prevalent (odds ratio 1·22, 95% confidence interval 1·05-1·43, P = 0·01) but not incident hypertension (odds ratio 0·93, 95% confidence interval 0·73-1·19, P = 0·58).

CONCLUSIONS

A modest association was found between increasing TSH and prevalent but not incident hypertension. TSH was inversely associated with BP change in men in our study. These findings contest an independent role of thyroid function at normal to near-normal levels in the pathogenesis of hypertension.

Endoplasmic reticulum stress: a novel mechanism and therapeutic target for cardiovascular diseases

Endoplasmic reticulum is a principal organelle responsible for folding, post-translational modifications and transport of secretory, luminal and membrane proteins, thus palys an important rale in maintaining cellular homeostasis. Endoplasmic reticulum stress (ERS) is a condition that is accelerated by accumulation of unfolded/misfolded proteins after endoplasmic reticulum environment disturbance, triggered by a variety of physiological and pathological factors, such as nutrient deprivation, altered glycosylation, calcium depletion, oxidative stress, DNA damage and energy disturbance, etc. ERS may initiate the unfolded protein response (UPR) to restore cellular homeostasis or lead to apoptosis. Numerous studies have clarified the link between ERS and cardiovascular diseases. This review focuses on ERS-associated molecular mechanisms that participate in physiological and pathophysiological processes of heart and blood vessels. In addition, a number of drugs that regulate ERS was introduced, which may be used to treat cardiovascular diseases. This review may open new avenues for studying the pathogenesis of cardiovascular diseases and discovering novel drugs targeting ERS.

Niacin Suppresses Progression of Atherosclerosis by Inhibiting Vascular Inflammation and Apoptosis of Vascular Smooth Muscle Cells

Background

Niacin is a broad-spectrum lipid-regulating drug used for the clinical therapy of atherosclerosis; however, the mechanisms by which niacin ameliorates atherosclerosis are not clear.

Material/Methods

The effect of niacin on atherosclerosis was assessed by detection of atherosclerotic lesion area. Adhesion molecules in arterial endothelial cells were determined by using qRT-PCR and Western blot analysis. The levels of serum inflammatory cytokines in ApoE^−/− mice were detected by using ELISA. We detected the expression levels of phosphorylated nuclear factors-κB (NF-κB) p65 in aortic endothelial cells of mice using Western blot analysis. Furthermore, we investigated the anti-inflammation effect and endothelium-protecting function of niacin and their regulatory mechanisms in vitro.

Results

Niacin inhibited the progress of atherosclerosis and decreased the levels of serum inflammatory cytokines and adhesion molecules in ApoE^−/− mice. Niacin suppressed the activity of NF-κB and apoptosis of vascular smooth muscle cells (VSMCs). Furthermore, niacin induced phosphorylated focal adhesion kinase (FAK) and FAK inhibitor PF-573228 reduced the level of Bcl-2 and elevated the level of cleaved caspase-3 in VSMCs.

Conclusions

Niacin inhibits vascular inflammation and apoptosis of VSMCs via inhibiting the NF-κB signaling and the FAK signaling pathway, respectively, thus protecting ApoE^−/− mice against atherosclerosis.

Sildenafil Protects against Myocardial Ischemia-Reperfusion Injury Following Cardiac Arrest in a Porcine Model: Possible Role of the Renin-Angiotensin System

Sildenafil, a phosphodiesterase-5 inhibitor sold as Viagra, is a cardioprotector against myocardial ischemia/reperfusion (I/R) injury. Our study explored whether sildenafil protects against I/R-induced damage in a porcine cardiac arrest and resuscitation (CAR) model via modulating the renin-angiotensin system. Male pigs were randomly divided to three groups: Sham group, Saline group, and sildenafil (0.5 mg/kg) group. Thirty min after drug infusion, ventricular fibrillation (8 min) and cardiopulmonary resuscitation (up to 30 min) was conducted in these animals. We found that sildenafil ameliorated the reduced cardiac function and improved the 24-h survival rate in this model. Sildenafil partly attenuated the increases of plasma angiotensin II (Ang II) and Ang (1–7) levels after CAR. Sildenafil also decreased apoptosis and Ang II expression in myocardium. The increases of expression of angiotensin-converting-enzyme (ACE), ACE2, Ang II type 1 receptor (AT1R), and the Ang (1–7) receptor Mas in myocardial tissue were enhanced after CAR. Sildenafil suppressed AT1R up-regulation, but had no effect on ACE, ACE2, and Mas expression. Sildenafilfurther boosted the upregulation of endothelial nitric oxide synthase (eNOS), cyclic guanosine monophosphate (cGMP) and inducible nitric oxide synthase(iNOS). Collectively, our results suggest that cardioprotection of sildenafil in CAR model is accompanied by an inhibition of Ang II-AT1R axis activation.

Chronic nicotine treatment enhances vascular smooth muscle relaxation in rats

AIM

To investigate the effect of chronic nicotine treatment on vascular function and to identify the underlying mechanisms.

METHODS

Adult rats were treated with nicotine (3 mg·kg(-1)·d(-1), sc) for 6 weeks. After the rats were sacrificed, aortic rings were prepared for detecting vascular reactivity, and thoracic aorta and periaortic fat samples were collected for histological and molecular biology studies.

RESULTS

Chronic nicotine treatment significantly reduced periaortic fat, and specifically enhanced smooth muscle relaxation without altering the aortic adventitial fat and endothelium function. Pretreatment with the soluble guanylyl cyclase inhibitor ODQ (3 μmol/L) or PKG inhibitor Rp-8-Br-PET-cGMP (30 μmol/L) abolished the nicotine-induced enhancement of smooth muscle relaxation, whereas the cGMP analogue 8-Br-cGMP could mimic the nicotine-induced enhancement of smooth muscle relaxation. However, the chronic nicotine treatment did not alter PKG protein expression and activity in aortic media.

CONCLUSION

Chronic nicotine treatment enhances vascular smooth muscle relaxation of rats via activation of PKG pathway.

Fibroblast growth factor 10 protects neuron against oxygen-glucose deprivation injury through inducing heme oxygenase-1

Fibroblast growth factors (FGFs) are a family of structurally related heparin-binding proteins with diverse biological functions. FGFs participate in mitogenesis, angiogenesis, cell proliferation, development, differentiation and cell migration. Here, we investigated the potential effect of FGF10, a member of FGFs, on neuron survival in oxygen-glucose deprivation (OGD) model. In primary cultured mouse cortical neurons upon OGD, FGF10 treatment (100 and 1000 ng/ml) attenuated the decrease of cell viability and rescued the LDH release. Tuj-1 immunocytochemistry assay showed that FGF10 promoted neuronal survival. Apoptosis assay with Annexin V+PI by flow cytometry demonstrated that FGF10 treatment reduced apoptotic cell proportion. Moreover, immunoblotting showed that FGF10 alleviated the cleaved caspase-3 upregulation caused by OGD. FGF10 treatment also depressed the OGD-induced increase of caspase-3, -8 and -9 activities. At last, we found FGF10 triggered heme oxygenase-1 (HO-1) protein expression rather than hypoxia-inducible factor-1 (HIF-1), AMP-activated protein kinase (AMPK) signaling and extracellular signal-regulated kinases 1/2 (ERK1/2) signaling. Knockdown of HO-1 by siRNA partly abolished the neuroprotection of FGF10 in OGD model. In summary, our observations provide the first evidence for the neuroprotective function of FGF10 against ischemic neuronal injury and suggest that FGF10 may be a promising agent for treatment of ischemic stroke.

Hypothyroidism affects differentially the cell size of epithelial cells among oviductal regions of rabbits

Oviductal regions show particular histological characteristics and functions. Tubal pathologies and hypothyroidism are related to primary and secondary infertility. The impact of hypothyroidism on the histological characteristics of oviductal regions has been scarcely studied. Our aim was to analyse the histological characteristics of oviductal regions in control and hypothyroid rabbits. Hypothyroidism was induced by oral administration of methimazole (MMI) for 30 days. For both groups, serum concentrations of thyroid and gonadal hormones were determined. Sections of oviductal regions were stained with the Masson's trichrome technique to analyse both epithelial and smooth muscle layers. The percentage of proliferative epithelial cells (anti-Ki67) in diverse oviductal regions was also quantified. Data were compared with Student t-test, Mann-Whitney U-test, or Fischer's test. In comparison with the control group, the hypothyroid group showed: (i) a low concentration of T3 and T4, but a high level of TSH; (ii) similar values of serum estradiol, progesterone and testosterone; (iii) a large size of ciliated cells in the ampulla (AMP), isthmus (IST) and utero-tubal junction (UTJ); (iv) a large size of secretory cells in the IST region; (v) a low percentage of proliferative secretory cells in the fimbria-infundibulum (FIM-INF) region; and (vi) a similar thickness of the smooth muscle layer and the cross-sectional area in the AMP and IST regions. Modifications in the size of the oviductal epithelium in hypothyroid rabbits could be related to changes in the cell metabolism that may impact on the reproductive functions achieved by oviduct.