Alpha2-Antiplasmin Is a Critical Regulator of Angiotensin II–Mediated Vascular Remodeling

α2-Antiplasmin is associated with macrophage activation and fibrin deposition in a macrophage activation syndrome mouse model

Macrophage activation syndrome (MAS) is a life-threatening condition, characterized by cytopenia, multi-organ dysfunction, and coagulopathy associated with excessive activation of macrophages. In this study, we investigated the roles of alpha2-antiplasmin (α2AP) in the progression of MAS using fulminant MAS mouse model induced by toll-like receptor-9 agonist (CpG) and D-(+)-galactosamine hydrochloride (DG). α2AP deficiency attenuated macrophage accumulation, liver injury, and fibrin deposition in the MAS model mice. Interferon-γ (IFN-γ) is associated with macrophage activation, including migration, and plays a pivotal role in MAS progression. α2AP enhanced the IFN-γ-induced migration, and tissue factor production. Additionally, we showed that fibrin-induced macrophage activation and tumor necrosis factor-α production. Moreover, the blockade of α2AP by neutralizing antibodies attenuated macrophage accumulation, liver injury, and fibrin deposition in the MAS model mice. These data suggest that α2AP may regulate IFN-γ-induced responses and be associated with macrophage activation and fibrin deposition in the MAS progression.

Identification of substrates of MBL Associated Serine Protease-1 (MASP-1) from human plasma using N-terminomics strategy

MBL Associated Serine Protease-1 (MASP-1) is an abundant enzyme of the lectin complement pathway. MASP-1 cleaves numerous substrates like MASP-2, MASP-3, C2, C3i, fibrinogen, FXIII and prothrombin. It has thrombin-like specificity and can cleave thrombin substrates. Owing to its high concentration and relaxed substrate specificity, MASP-1 has substrates outside the complement system and can influence other proteolytic cascades and physiological processes. The unidentified substrates may assist us to ascertain the role(s) of MASP-1. In this study, we used a high-throughput N-terminomics method to identify substrates of MASP-1 from human plasma. We have identified 35 putative substrates of MASP-1. Among the identified proteins, alpha 2-antiplasmin, alpha-1-acid glycoprotein, antithrombin III, and siglec-6 were demonstrated to be cleaved by MASP-1. We have discussed the physiological relevance of cleavage of these substrates by MASP-1. The expression of Siglec-6 and MASP-1 has been reported in the B cells. Alpha-1-acid glycoprotein cleavage by MASP-1 may occur in the acute phase as it is known to be an inhibitor of platelet aggregation, whereas MASP-1 triggers platelet aggregation. The cleavage alpha2 antiplasmin by MASP-1 implies that MASP-1 may be promoting plasmin-mediated fibrinolysis. Our study supports that MASP-1 may be implicated in thrombosis as well as thrombolysis.

α2-Antiplasmin as a Potential Therapeutic Target for Systemic Sclerosis

Systemic sclerosis is a connective tissue disease of unknown origin that is characterized by immune system abnormalities, vascular damage, and extensive fibrosis of the skin and visceral organs. α2-antiplasmin is known to be the main plasmin inhibitor and has various functions such as cell differentiation and cytokine production, as well as the regulation of the maintenance of the immune system, endothelial homeostasis, and extracellular matrix metabolism. The expression of α2-antiplasmin is elevated in dermal fibroblasts from systemic sclerosis patients, and the blockade of α2-antiplasmin suppresses fibrosis progression and vascular dysfunction in systemic sclerosis model mice. α2-antiplasmin may have promise as a potential therapeutic target for systemic sclerosis. This review considers the role of α2-antiplasmin in the progression of systemic sclerosis.

Early Pregnancy Exposure to Ambient Air Pollution among Late-Onset Preeclamptic Cases Is Associated with Placental DNA Hypomethylation of Specific Genes and Slower Placental Maturation

Exposure to ambient air pollution during pregnancy has been associated with an increased risk of preeclampsia (PE). Some suggested mechanisms behind this association are changes in placental DNA methylation and gene expression. The objective of this study was to identify how early pregnancy exposure to ambient nitrogen oxides (NO_x) among PE cases and normotensive controls influence DNA methylation (EPIC array) and gene expression (RNA-seq). The study included placentas from 111 women (29 PE cases/82 controls) in Scania, Sweden. First-trimester NO_x exposure was assessed at the participants’ residence using a dispersion model and categorized via median split into high or low NO_x. Placental gestational epigenetic age was derived from the DNA methylation data. We identified six differentially methylated positions (DMPs, q < 0.05) comparing controls with low NO_x vs. cases with high NO_x and 14 DMPs comparing cases and controls with high NO_x. Placentas with female fetuses showed more DMPs (N = 309) than male-derived placentas (N = 1). Placentas from PE cases with high NO_x demonstrated gestational age deceleration compared to controls with low NO_x (p = 0.034). No differentially expressed genes (DEGs, q < 0.05) were found. In conclusion, early pregnancy exposure to NO_x affected placental DNA methylation in PE, resulting in placental immaturity and showing sexual dimorphism.

A metabolomic index based on lipoprotein subfractions and branched chain amino acids is associated with incident hypertension

OBJECTIVE

The present study aims to evaluate the performance of the Diabetes Risk Index (DRI), a metabolomic index based on lipoprotein particles and branched chain amino acids, on the incidence of newly developed hypertension in a large community dwelling cohort.

METHODS

The DRI was calculated by combining 6 lipoprotein parameters [sizes of very-low-density lipoprotein (VLDL), low-density lipoprotein (LDL) and high-density lipoprotein (HDL), concentrations of large VLDL, small LDL, and large HDL particles], and the concentrations of valine and leucine. DRI scores were estimated in 4169 participants from the PREVEND prospective cohort. Cox proportional hazards regression was used to evaluate the association of DRI scores with incident hypertension.

RESULTS

During a median follow-up of 8.6 years, 924 new hypertension cases were ascertained. In analyses adjusted for age and sex, there was a significant association between DRI and incident hypertension with a hazard ratio (HR) per 1 SD increase of 1.45 (95% CI 1.36,1.54; p < 0.001). After additional adjustment for traditional risk factors, the HR remained significant (HR_adj 1.21, 95% CI 1.10, 1.33, p <0.001). Likewise, subjects in the top quartile of DRI presented with a higher risk of hypertension (HR_adj 1.64, 95% CI 1.28, 2.10, p <0.001). Furthermore, the net reclassification improvement assessment improved after the addition of DRI to a traditional risk model (p <0.001), allowing proper reclassification of 34% of the participants.

CONCLUSION

Higher DRI scores were associated with an increased risk of incident hypertension. Such association was independent of traditional clinical risk factors for hypertension.

MicroRNA-30c attenuates fibrosis progression and vascular dysfunction in systemic sclerosis model mice

Systemic sclerosis (SSc) is characterized by peripheral circulatory disturbance and fibrosis in skin and visceral organs. We recently demonstrated that α2-antiplasmin (α2AP) is elevated in SSc dermal fibroblasts and SSc model mice, and is associated with fibrosis progression and vascular dysfunction. In the present study, we predicted that α2AP could be a target of microRNA-30c (miR-30c) using TargetScan online database, and investigated the effect of miR-30c on the pathogenesis of SSc using a bleomycin-induced SSc model mice. miR-30c attenuated α2AP expression, and prevented the pro-fibrotic changes (increased dermal thickness, collagen deposition, myofibroblast accmulation) and the vascular dysfunction (the reduction of vascular endothelial cells (ECs) and blood flow) in the skin of SSc model mice. Furthermore, miR-30c suppressed pulmonary fibrosis progression in the SSc model mice. miR-30c exerts the anti-fibrotic and anti-angiopathy effects on SSc model mice, and might provide a basis for clinical strategies for SSc.

Alpha2-Antiplasmin: The Devil You Don't Know in Cerebrovascular and Cardiovascular Disease

Alpha2-antiplasmin (α2AP), the fast-reacting, serine protease inhibitor (serpin) of plasmin, was originally thought to play a key role in protection against uncontrolled, plasmin-mediated proteolysis of coagulation factors and other molecules. However, studies of humans and mice with genetic deficiency of α2AP have expanded our understanding of this serpin, particularly in disease states. Epidemiology studies have shown an association between high α2AP levels and increased risk or poor outcome in cardiovascular diseases. Mechanistic studies in disease models indicate that α2AP stops the body's own fibrinolytic system from dissolving pathologic thrombi that cause venous thrombosis, pulmonary embolism, arterial thrombosis, and ischemic stroke. In addition, α2AP fosters the development of microvascular thrombosis and enhances matrix metalloproteinase-9 expression. Through these mechanisms and others, α2AP contributes to brain injury, hemorrhage and swelling in experimental ischemic stroke. Recent studies also show that α2AP is required for the development of stasis thrombosis by inhibiting the early activation of effective fibrinolysis. In this review, we will discuss the key role played by α2AP in controlling thrombosis and fibrinolysis and, we will consider its potential value as a therapeutic target in cardiovascular diseases and ischemic stroke.

Alternatively activated macrophages are associated with the α2AP production that occurs with the development of dermal fibrosis : The role of alternatively activated macrophages on the development of fibrosis

Background

Fibrotic diseases are characterized by tissue overgrowth, hardening, and/or scarring because of the excessive production, deposition, and contraction of the extracellular matrix (ECM). However, the detailed mechanisms underlying these disorders remain unclear. It was recently reported that α2-antiplasmin (α2AP) is elevated in fibrotic tissue and that it is associated with the development of fibrosis. In the present study, we examined the mechanism underlying the production of α2AP on the development of fibrosis.

Methods

To clarify the mechanism underlying the production of α2AP on the development of fibrosis, we focused on high-mobility group box 1 (HMGB1), which is associated with the development of fibrosis. The mouse model of bleomycin-induced fibrosis was used to evaluate the production of α2AP on the development of fibrosis.

Results

We found that HMGB1 induced the production of α2AP through receptor for advanced glycation end products (RAGE) in fibroblasts. Next, we showed that macrophage reduction by a macrophage-depleting agent, clodronate, attenuated the progression of fibrosis and the production of α2AP and HMGB1 in the bleomycin-induced mice. We also showed that IL-4-stimulated alternatively activated macrophages induced the production of HMGB1, that IL-4-stimulated alternatively activated macrophage conditioned media (CM) induced pro-fibrotic changes and α2AP production, and that the inhibition of HMGB1 and RAGE attenuated these effects in fibroblasts. Furthermore, the blockade of IL-4 signaling by IL-4Rα neutralizing antibodies attenuated the progression of fibrosis and the production of α2AP and HMGB1 in the bleomycin-induced mice.

Conclusion

These findings suggest that alternatively activated macrophage-derived HMGB1 induced the production of α2AP through RAGE and that these effects are associated with the development of fibrosis. Our findings may provide a clinical strategy for managing fibrotic disorders.

Vasculoprotective effects of Centella asiatica, Justicia gendarussa and Imperata cylindrica decoction via the NOXs-ROS-NF-κB pathway in spontaneously hypertensive rats

Background and aim

Centella asiatica, Justicia gendarussa and Imperata cylindrica decoction (CJID) is efficacious for hypertension. NADPH (nicotinamide adenine dinucleotide phosphate) oxidase (NOX)-induced reactive oxygen species (ROS) generation modulates nuclear factor kappa B (NF-κB) activation and thus mediates hypertension-induced vascular remodeling. This research aims to investigate the anti-remodeling effect of CJID through the mechanism of NOXs-ROS-NF-κB pathway in spontaneously hypertensive rats (SHRs).

Experimental procedure

CJID was orally administered once a day for five weeks in SHRs and normotensive-WKY (Wistar Kyoto) rats. All rats were sacrificed at the end of study and different assays were performed to determine whether CJID ameliorates vascular remodeling in SHRs, such as histological examination; lactate dehydrogenase (LDH), nitric oxide (NO), malondialdehyde (MDA) and superoxide dismutase (SOD) assays; superoxide and hydrogen peroxide (H₂O₂) generation assays, immunohistochemistry and immunofluorescence assays. . Changes in levels of inducible nitric oxide synthase (iNOS), NF-κB-p65, NF-κB inhibitor alpha/IκBα (inhibitory kappa B- alpha), phosphorylation of IκBα (p-IκBα) and NOX1, NOX2, NOX4 in the thoracic aorta were determined.

Results

Vascular remodeling indicators, media thickness, collagen and elastic accumulation in the thoracic aorta, of SHRs-treated CJID were attenuated. Redox homeostasis, aortic superoxide and hydrogen peroxide generation were decreased in SHRs-treated group. Aortic iNOS, p-IκBα, NF-κB-p65 and NOX1, NOX2, NOX4 expressions were suppressed.

Conclusions

CJI treatment diminishes oxidative stress response in the thoracic aorta of SHRs via regulation of NOXs-ROS-NF-κB signaling pathway. These findings indicate that CJI possess protective effect against hypertension-induced vascular remodeling in SHRs.

The Role of Fibrinolytic Regulators in Vascular Dysfunction of Systemic Sclerosis

Systemic sclerosis (SSc) is a connective tissue disease of autoimmune origin characterized by vascular dysfunction and extensive fibrosis of the skin and visceral organs. Vascular dysfunction is caused by endothelial cell (EC) apoptosis, defective angiogenesis, defective vasculogenesis, endothelial-to-mesenchymal transition (EndoMT), and coagulation abnormalities, and exacerbates the disease. Fibrinolytic regulators, such as plasminogen (Plg), plasmin, α2-antiplasmin (α2AP), tissue-type plasminogen activator (tPA), urokinase-type plasminogen activator (uPA) and its receptor (uPAR), plasminogen activator inhibitor 1 (PAI-1), and angiostatin, are considered to play an important role in the maintenance of endothelial homeostasis, and are associated with the endothelial dysfunction of SSc. This review considers the roles of fibrinolytic factors in vascular dysfunction of SSc.

α2AP regulates vascular alteration by inhibiting VEGF signaling in systemic sclerosis: the roles of α2AP in vascular dysfunction in systemic sclerosis

BACKGROUND

Systemic sclerosis (SSc) is a connective tissues disease of unknown origin characterized by vascular damage and extensive fibrosis. Recently, we demonstrated that α2-antiplasmin (α2AP) is associated with the development of fibrosis in SSc. We herein investigate the roles of α2AP in vascular dysfunction in SSc.

METHODS

Vascular damage in mice was determined by the levels of blood vessels and blood flow. Vascular functions in vascular endothelial cells (ECs) were determined by the levels of tube formation, cell proliferation, and endothelial junction-associated protein (VE-cadherin and PECAM1) production.

RESULTS

The administration of α2AP induced vascular damage in mice. Conversely, the α2AP neutralization improved vascular damage in a bleomycin-induced mouse model of SSc. Additionally, we showed that the SSc fibroblast-conditioned media induced the reduction of tube formation, cell proliferation, and endothelial junction-associated protein production in ECs, and that α2AP neutralization improved them. We also examined the mechanisms underlying the effects of α2AP on vascular alteration in SSc and found that α2AP attenuated vascular endothelial growth factor-induced tube formation, cell proliferation, and endothelial junction-associated protein production through the adipose triglyceride lipase/tyrosine phosphatase SHP2 axis in ECs.

CONCLUSION

Our findings demonstrate that α2AP is associated with vascular alteration, and that the blocking of α2AP improves vascular dysfunction in SSc.

The Antifibrotic Effect of α2AP Neutralization in Systemic Sclerosis Dermal Fibroblasts and Mouse Models of Systemic Sclerosis

Systemic sclerosis (SSc) is a connective tissue disease of autoimmune origin characterized by the fibrosis of skin and visceral organs, and peripheral circulatory disturbance. We recently demonstrated that α2-antiplasmin (α2AP), which is the physiological inhibitor of plasmin, is associated with the development of fibrosis. The aim of this study was to clarify the role of α2AP in the pathogenesis of SSc. The administration of α2AP in mice induced profibrotic changes, such as increased dermal thickness, collagen production, and myofibroblast differentiation. Conversely, the α2AP neutralization prevented not only profibrotic changes, but also the production of autoantibodies in bleomycin-induced mouse models of SSc. The expression of α2AP was elevated in dermal fibroblasts obtained from patients with SSc. Furthermore, α2AP treatment promoted profibrotic changes in human normal dermal fibroblasts, and α2AP neutralization reversed a profibrotic phenotype of SSc dermal fibroblasts, in the absence of plasmin. Our findings demonstrated that α2AP has a profibrotic effect probably not by the action as a plasmin inhibitor, and that the blocking of α2AP exerts an antifibrotic effect in humans and mice with SSc.

Luteolin Ameliorates Hypertensive Vascular Remodeling through Inhibiting the Proliferation and Migration of Vascular Smooth Muscle Cells

Objectives. Preliminary researches showed that luteolin was used to treat hypertension. However, it is still unclear whether luteolin has effect on the hypertensive complication such as vascular remodeling. The present study was designed to investigate the effect of luteolin on the hypertensive vascular remodeling and its molecular mechanism. Method and Results. We evaluated the effect of luteolin on aorta thickening of hypertension in spontaneous hypertensive rats (SHRs) and found that luteolin could significantly decrease the blood pressure and media thickness of aorta in vivo. Luteolin could inhibit angiotensin II- (Ang II-) induced proliferation and migration of vascular smooth muscle cells (VSMCs). Dichlorofluorescein diacetate (DCFH-DA) staining result showed that luteolin reduced Ang II-stimulated ROS production in VSMCs. Furthermore, western blot and gelatin zymography results showed that luteolin treatment leaded to a decrease in ERK1/2, p-ERK1/2, p-p38, MMP2, and proliferating cell nuclear antigen (PCNA) protein level. Conclusion. These data support that luteolin can ameliorate hypertensive vascular remodeling by inhibiting the proliferation and migration of Ang II-induced VSMCs. Its mechanism is mediated by the regulation of MAPK signaling pathway and the production of ROS.

Role of extracellular matrix in vascular remodeling of hypertension

PURPOSE OF REVIEW

Arterial stiffness due to alterations in extracellular matrix is one of the mechanisms responsible for increased peripheral resistance in hypertension. Recent evidence points to arterial stiffness as an independent predictor of cardiovascular events. This review focuses on recent advances in the biology of extracellular matrix proteins involved in hypertension-associated vascular changes.

RECENT FINDINGS

The vascular extracellular matrix is a complex heterogeneous tissue comprising collagens, elastin, glycoproteins, and proteoglycans. These constituents not only provide mechanical integrity to the vessel wall but also possess a repertoire of insoluble ligands that induce cell signaling to control proliferation, migration, differentiation, and survival. It is now evident that it is not only the quantity but also the quality of the new synthesized extracellular matrix that determines changes in vascular stiffness in hypertension. Also, the control of cross-linking and the interactions between the extracellular matrix and vascular cells seem to be important.

SUMMARY

It is now evident that some of the currently used antihypertensive therapies can correct vascular stiffness and fibrosis. A better understanding of molecular mechanisms underlying alterations in extracellular matrix in hypertension will provide insights into novel therapies to reduce arterial stiffness and will identify new roles of established antihypertensive drugs.

Other Transgenic Animal Models Used in Cardiovascular Studies

Previous chapters have described a large number of transgenic animal models used to study specific cardiovascular syndromes. This chapter will fill in some gaps. Many of these transgenic animals were developed to study normal and/or abnormal physiological responses in other organ systems, or to study basic biochemical and molecular reactions or pathways. These models were then discovered to also have effects on the cardiovascular system, some of them unanticipated.

A word of caution, particularly when highly inbred mouse strains are used to develop transgenic models - not all strains of a particular species are created equal. When cardiovascular parameters of age- and sex-matched A/J and C57BL/6J inbred mice were compared the C57BL/6J mice demonstrated eccentric physiologic ventricular hypertrophy, increased ventricular function, lower heart rates, and increased exercise endurance.¹