Evidence for a role of collagen synthesis in arterial smooth muscle cell migration

Collagen-mediated cardiovascular calcification

Cardiovascular calcification is a pathological process commonly observed in the elderly. Based on the location of the calcification, cardiovascular calcification can be classified into two main types: vascular calcification and valvular calcification. Collagen plays a critical role in the development of cardiovascular calcification lesions. The content and type of collagen are the result of a dynamic balance between synthesis and degradation. Unregulated processes can lead to adverse outcomes. During cardiovascular calcification, collagen not only serves as a scaffold for ectopic mineral deposition but also acts as a signal transduction pathway that mediates calcification by guiding the aggregation and nucleation of matrix vesicles and promoting the proliferation, migration and phenotypic changes of cells involved in the lesion. This review provides an overview of collagen subtypes in the cardiovascular system under physiological conditions and discusses their distribution. Additionally, we introduce pathological changes and mechanisms of collagen in blood vessels and heart valves. Then, the formation process and characteristic stages of cardiovascular calcification are described. Finally, we highlight the role of collagen in cardiovascular calcification, explore strategied for mediating calcification, and suggest potential directions for future research.

Survivin modulates stiffness-induced vascular smooth muscle cell motility

Arterial stiffness is a key contributor to cardiovascular diseases, including atherosclerosis, restenosis, and coronary artery disease, it has been characterized to be associated with the aberrant migration of vascular smooth muscle cells (VSMCs). However, the underlying molecular mechanisms driving VSMC migration in stiff environments remain incompletely understood. We recently demonstrated that survivin, a member of the inhibitor of apoptosis protein family, is highly expressed in both mouse and human VSMCs cultured on stiff polyacrylamide hydrogels, where it modulates stiffness-mediated cell cycle progression and proliferation. However, its role in stiffness-dependent VSMC migration remains unknown. To assess its impact on migration, we performed time-lapse video microscopy on VSMCs seeded on fibronectin-coated soft and stiff polyacrylamide hydrogels, mimicking the physiological stiffness of normal and diseased arteries, with either survivin inhibition or overexpression. We observed that VSMC motility increased under stiff conditions, while pharmacologic or siRNA-mediated inhibition of survivin reduced stiffness-stimulated migration to rates similar to those observed under soft conditions. Further investigation revealed that cells on stiff hydrogels exhibited greater directional movement and robust lamellipodial protrusion compared to those on soft hydrogels. Interestingly, survivin-inhibited cells on stiff hydrogels showed reduced directional persistence and lamellipodial protrusion compared to control cells. We also examined whether survivin overexpression alone is sufficient to induce cell migration on soft hydrogels, and found that survivin overexpression modestly increased cell motility and partially rescued the lack of directional persistence compared to GFP-expressing control VSMCs on soft hydrogels. In conclusion, our findings demonstrate that survivin plays a key role in regulating stiffness-induced VSMC migration, suggesting that targeting survivin and its signaling pathways could offer therapeutic strategies for addressing arterial stiffness in cardiovascular diseases.

Resonating with Cellular Pathways: Transcriptome Insights into Nonthermal Bioeffects of Middle Infrared Light Stimulation and Vibrational Strong Coupling on Cell Proliferation and Migration

Middle infrared stimulation (MIRS) and vibrational strong coupling (VSC) have been separately applied to physically regulate biological systems but scarcely compared with each other, especially at identical vibrational frequencies, though they both involve resonant mechanism. Taking cell proliferation and migration as typical cell-level models, herein, we comparatively studied the nonthermal bioeffects of MIRS and VSC with selecting the identical frequency (53.5 THz) of the carbonyl vibration. We found that both MIRS and VSC can notably increase the proliferation rate and migration capacity of fibroblasts. Transcriptome sequencing results reflected the differential expression of genes related to the corresponding cellular pathways. This work not only sheds light on the synergistic nonthermal bioeffects from the molecular level to the cell level but also provides new evidence and insights for modifying bioreactions, further applying MIRS and VSC to the future medicine of frequencies.

Modular Toolbox as Snap Jewelry for Biomimetic Synthesis of Multifunctional Amino Acid Surfactants Inspired by Melanin

Amino acid surfactants have gained significant importance in overcoming the limitations of conventional surfactants, notably, their low biocompatibility and biodegradability. However, the current amino acid surfactants lack multifunctional properties due to the nonreactivity of their aliphatic chains, necessitating the development of a new type of amino acid surfactant. A novel melanin-like amino acid surfactant and a biomimetic synthesis route were devised by mimicking the biosynthesis of melanin. Renewable natural polyphenol compounds with catechol moieties were utilized as building blocks for the hydrophobic group. In a proof-of-concept experiment, ethyl protocatechuate was oxidized to o-quinone and subsequently covalently linked to the amino group of lysine via Michael addition. The chemical structure was verified using liquid chromatography-tandem mass spectroscopy. The melanin-like amino acid surfactant exhibited excellent surface-active properties, with a critical micelle concentration of 1.59 mN m-1. Furthermore, it demonstrated remarkable emulsifying, foaming, solubilizing, dispersing, and wetting capabilities. Notably, it also possessed multifunctionality, including antibacterial activity, antioxidant activity, robustness, and mildness. These outstanding properties indicate significant potential for various applications. This strategy offers innovative insights and a versatile, modular toolbox for synthesizing multifunctional amino acid surfactants that mimic melanin. The approach allows for the easy interchange of o-quinone building blocks, which is akin to snap jewelry.

Novel signaling axis of FHOD1-RNF213-Col1α/Col3α in the pathogenesis of hypertension-induced tunica media thickening

Hypertension-induced tunica media thickening (TMT) is the most important fundamental for the subsequent complications like stroke and cardiovascular diseases. Pathogenically, TMT originates from both vascular smooth muscle cells (VSMCs) hypertrophy due to synthesizing more amount of intracellular contractile proteins and excess secretion of extracellular matrix. However, what key molecules are involved in the pathogenesis of TMT is unknown. We hypothesize that formin homology 2 domain-containing protein 1 (FHOD1), an amply expressed mediator for assembly of thin actin filament in VSMCs, is a key regulator for the pathogenesis of TMT. In this study, we found that FHOD1 expression and its phosphorylation/activation were both upregulated in the arteries of three kinds of hypertensive rats. Ang-II induced actin filament formation and hypertrophy through activation and upregulation of FHOD1 in VSMCs. Active FHOD1-mediated actin filament assembly and secretions of collagen-1α/collagen-3α played crucial roles in Ang-II-induced VSMCs hypertrophy in vitro and hypertensive TMT in vivo. Proteomics demonstrated that activated FL-FHOD1 or its C-terminal diaphanous-autoregulatory domain significantly upregulated RNF213 (ring finger protein 213), a 591-kDa cytosolic E3 ubiquitin ligase with its loss-of-functional mutations being a susceptibility gene for Moyamoya disease which has prominent tunica media thinning in both intracranial and systemic arteries. Mechanistically, activated FHOD1 upregulated its downstream effector RNF213 independently of its classical pathway of decreasing G-actin/F-actin ratio, transcription, and translation, but dependently on its C-terminus-mediated stabilization of RNF213 protein. FHOD1-RNF213 signaling dramatically promoted collagen-1α/collagen-3α syntheses in VSMCs. Our results discovered a novel signaling axis of FHOD1-RNF213-collagen-1α/collagen-3α and its key role in the pathogenesis of hypertensive TMT.

Integrated Cascade Nanozymes with Antisenescence Activities for Atherosclerosis Therapy

Senescent cells are the critical drivers of atherosclerosis formation and maturation. Mitigating senescent cells holds promise for the treatment of atherosclerosis. In an atherosclerotic plaque microenvironment, senescent cells interact with reactive oxygen species (ROS), promoting the disease development. Here, we hypothesize that a cascade nanozyme with antisenescence and antioxidant activities can serve as an effective therapeutic for atherosclerosis. An integrated cascade nanozyme with superoxide dismutase- and glutathione peroxidase-like activities, named MSe1 , is developed in this work. The obtained cascade nanozyme can attenuate human umbilical vein endothelial cell (HUVEC) senescence by protecting DNA from damage. It significantly weakens inflammation in macrophages and HUVECs by eliminating overproduced intracellular ROS. Additionally, the MSe1 nanozyme effectively inhibits foam cell formation in macrophages and HUVECs by decreasing the internalization of oxidized low-density lipoprotein. After intravenous administration, the MSe1 nanozyme significantly inhibits the formation of atherosclerosis in apolipoprotein E-deficient (ApoE-/- ) mice by reducing oxidative stress and inflammation and then decreases the infiltration of inflammatory cells and senescent cells in atherosclerotic plaques. This study not only provides a cascade nanozyme but also suggests that the combination of antisenescence and antioxidative stress holds considerable promise for treating atherosclerosis.

Polymorphisms and gene expression of metalloproteinases and their inhibitors associated with cerebral ischemic stroke in young patients with sickle cell anemia

BACKGROUND

Sickle cell anemia (SCA) is a genetic disease with great clinical heterogeneity and few viable strategies for treatment; hydroxyurea (HU) is the only widely used drug. Thus, the study of single nucleotide polymorphisms (SNPs) and the gene expression of MMPs 1, 2, 9, 7 and TIMPs 1 and 2, which are involved in the regulation of extracellular matrix, inflammation, and neuropathies, may provide further insights into the pathophysiology of the disease and elucidate biomarkers and molecules as potential therapeutic targets for patients with SCA.

METHODS AND RESULTS

We evaluated 251 young individuals with SCA from northeastern Brazil. The groups were divided according to vaso-occlusive crisis (VOC) and cerebrovascular disease (CVD), compared to control individuals. SNP detection and gene expression assays were performed by real-time PCR, TaqMan system®. Both the expression levels of MMP1 gene, and the SNP MMP1-1607 1G/2G were associated with the risk of cerebral ischemic stroke (IS), and the expression of MMP1 was also associated with a higher frequency of VOC/year. Expression levels of MMP7, TIMP1, and TIMP2 were increased in patients conditioned to IS. The SNP 372T>C (rs4898) TIMP1 T alleles were more frequent in patients with > 5 VOC events/year. The SNP rs17576 of MMP9 showed differences in gene expression levels; it was increased in the genotypes AG, and AG+GG.

CONCLUSION

The findings of this study, the SNPs, and expression provide initial support for understanding the role of MMPs-TIMPs in the pathophysiology of SCA in young patients.

Exploring the difference in the mechanics of vascular smooth muscle cells from wild-type and apolipoprotein-E knockout mice

Atherosclerosis-related cardiovascular diseases are a leading cause of mortality worldwide. Vascular smooth muscle cells (VSMCs) comprise the medial layer of the arterial wall and undergo phenotypic switching during atherosclerosis to a synthetic phenotype capable of proliferation and migration. The surrounding environment undergoes alterations in extracellular matrix (ECM) stiffness and composition and an increase in cholesterol content. Using an atherosclerotic murine model, we analyzed how the mechanics of VSMCs isolated from Western diet-fed apolipoprotein-E knockout (ApoE-/-) and wild-type (WT) mice were altered during atherosclerosis. Increased stiffness of ApoE-/- VSMCs correlated with a greater degree of stress fiber alignment, as evidenced by atomic force microscopy (AFM)-generated force maps and stress fiber topography images. On type-1 collagen (COL1)-coated polyacrylamide (PA) gels (referred to as substrate) of varying stiffness, ApoE-/- VSMCs had lower adhesion forces to COL1 and N-cadherin (N-Cad) compared with WT cells. ApoE-/- VSMC stiffness was significantly greater than that of WT cells. Cell stiffness increased with increasing substrate stiffness for both ApoE-/- and WT VSMCs. In addition, ApoE-/- VSMCs showed an enhanced migration capability on COL1-coated substrates and a general decreasing trend in migration capacity with increasing substrate stiffness, correlating with lowered adhesion forces as compared with WT VSMCs. Altogether, these results demonstrate the potential contribution of the alteration in VSMC mechanics in the development of atherosclerosis.

Role of Sp1 in atherosclerosis

Specificity protein (Sp) is a famous family of transcription factors including Sp1, Sp2 and Sp3. Sp1 is the first one of Sp family proteins to be characterized and cloned in mammalian. It has been proposed that Sp1 acts as a modulator of the expression of target gene through interacting with a series of proteins, especially with transcriptional factors, and thereby contributes to the regulation of diverse biological processes. Notably, growing evidence indicates that Sp1 is involved in the main events in the development of atherosclerosis (AS), such as inflammation, lipid metabolism, plaque stability, vascular smooth muscle cells (VSMCs) proliferation and endothelial dysfunction. This review is designed to provide useful clues to further understanding roles of Sp1 in the pathogenesis of AS, and may be helpful for the design of novel efficacious therapeutics agents targeting Sp1.

A collagen I derived matricryptin increases aorta vascular wall remodeling after induced thrombosis in mouse

Matricryptins are collagen fragments proteolytically released from the extracellular matrix (ECM) with biological activity that can regulate several processes involved in ECM remodeling. Vessel wall matrix reorganization after lesion is important to the recovery of vascular function. This study aimed to analyze the effect of the peptide p1158/59 (Lindsey, 2015) on thrombosis, neointimal formation, and vascular remodeling of C57BL6 mice abdominal aorta. We used a FeCl₃ induced vascular injury mice model and analyzed thrombus size, neointima formation, gelatinase activities in situ, re-endothelization, and collagen fibers organization on the arterial wall using polarization microscopy. As result, we observed that 2 days after injury the treatment with p1158/59 increased thrombus size and gelatinase activity, vascular lesion and it did not recover the endothelium loss induced by the chemical injury. We also observed that the peptide increased neointima growth and collagen birefringence, indicating collagen fibers reorganization. It also promoted increased re-endothelization and decreased activity of gelatinases 14 days after injury. Thus, we conclude that the peptide p1158/59 impaired the initial thrombosis recovery 2 days after injury but was able to induce vascular ECM remodeling after 14 days, improving vessel re-endothelization, collagen fibers deposition, and organization.

Ablation of Collagen VI leads to the release of platelets with altered function

Megakaryocytes express collagen VI that regulates the release of functional platelets.

Collagen VI–null megakaryocytes and platelets display increased mTOR signaling and store-operated calcium entry.

Hemostatic abnormalities and impaired platelet function have been described in patients affected by connective tissue disorders. We observed a moderate bleeding tendency in patients affected by collagen VI–related disorders and investigated the defects in platelet functionality, whose mechanisms are unknown. We demonstrated that megakaryocytes express collagen VI that is involved in the regulation of functional platelet production. By exploiting a collagen VI–null mouse model (Col6a1^−/−), we found that collagen VI–null platelets display significantly increased susceptibility to activation and intracellular calcium signaling. Col6a1^−/− megakaryocytes and platelets showed increased expression of stromal interaction molecule 1 (STIM1) and ORAI1, the components of store-operated calcium entry (SOCE), and activation of the mammalian target of rapamycin (mTOR) signaling pathway. In vivo mTOR inhibition by rapamycin reduced STIM1 and ORAI1 expression and calcium flows, resulting in a normalization of platelet susceptibility to activation. These defects were cell autonomous, because transplantation of lineage-negative bone marrow cells from Col6a1^−/− mice into lethally irradiated wild-type animals showed the same alteration in SOCE and platelet activation seen in Col6a1^−/− mice. Peripheral blood platelets of patients affected by collagen VI–related diseases, Bethlem myopathy and Ullrich congenital muscular dystrophy, displayed increased expression of STIM1 and ORAI1 and were more prone to activation. Altogether, these data demonstrate the importance of collagen VI in the production of functional platelets by megakaryocytes in mouse models and in collagen VI–related diseases.

Fibroblasts treated with macrophage conditioned medium results in phenotypic shifts and changes in collagen organization

In tissue regeneration, the goal is to regenerate tissue similar to what was damaged or missing while preventing fibrotic scarring, which may lead to decreased mechanical strength and dissimilar tissue characteristics compared to native tissue. We believe collagen orientation plays a critical role in wound contraction and scarring and that it is modulated by myofibroblasts. We used macrophage conditioned medium to simulate complex events that can influence the fibroblast phenotype during the wound healing process. In addition to examining the effect of macrophage phenotype on fibroblasts, we inhibited focal adhesion kinase (FAK), Rho-associated protein kinase (ROCK), and myosin II for fibroblasts cultured on both tissue culture plastic and methacrylated gellan gum to understand how different pathways and materials influence fibroblast responses. Collagen orientation, α-SMA expression, focal adhesion area, and cell migration were altered by inhibition of FAK, ROCK, or myosin II and macrophage phenotype, along with the substrate. An increase in either focal adhesion area or α-smooth muscle actin (α-SMA) expression correlated with an aligned collagen orientation. Gellan gum hydrogels upregulated α-SMA expression in ROCK inhibited conditioned media and downregulated the FAK area in FAK and ROCK inhibited conditioned media. Myosin II had no impact on the α-SMA expression on the substrate compared to coverslip except for M2 conditioned medium. Gellan gum hydrogel significantly increased cell migration under FAK and Myosin II mediated conditioned media and unconditioned media. Collectively, our study examined how macrophage phenotype influences fibroblast response, which would be beneficial in controlling scar tissue formation.

The antiplatelet agent revacept prevents the increase of systemic thromboxane A2 biosynthesis and neointima hyperplasia

Neointima hyperplasia is a crucial component of restenosis after coronary angioplasty. We have hypothesized that enhanced generation of platelet-derived thromboxane (TX)A₂ in response to vascular damage plays a critical role in neointimal hyperplasia and that antiplatelet agents may mitigate it. In cocultures of human platelets and coronary artery smooth muscle cells (CASMC), we found that platelets induced morphologic changes and enhanced the migration of CASMC. The exposure of platelets to Aspirin [an inhibitor of cyclooxygenase (COX)-1] reduced the generation of TXA₂ and prevented the morphological and functional changes induced by platelets in CASMC. Platelet-derived TXA₂ induced COX-2 and enhanced prostaglandin (PG)E₂ biosynthesis in CASMC, a known mechanism promoting neointimal hyperplasia. COX-2 induction was prevented by different antiplatelet agents, i.e., Aspirin, the TP antagonist SQ29,548, or Revacept (a dimeric soluble GPVI-Fc fusion protein). The administration of the novel antiplatelet agent Revacept to C57BL/6 mice, beginning three days before femoral artery denudation, and continuing up to seven days after injury, prevented the increase of the systemic biosynthesis di TXA₂ and reduced femoral artery intima-to-media area and the levels of markers of cell proliferation and macrophage infiltration. Revacept might serve as a therapeutic agent for percutaneous coronary angioplasty and stent implantation.

Slow degrading poly(glycerol sebacate) derivatives improve vascular graft remodeling in a rat carotid artery interposition model

Porous synthetic grafts made of poly (glycerol sebacate) (PGS) can transform into autologous vascular conduits in vivo upon degradation of PGS. A long-held doctrine in tissue engineering is the necessity to match degradation of the scaffolds to tissue regeneration. Here, we tested the impact of degradation of PGS and its derivative in an interposition model of rat common carotid artery (CCA). Previous work indicates a complete degradation of PGS within approximately 2 weeks, likely at the fast end of the spectrum. Thus, the derivation of PGS focuses on delay degradation by conjugating the free hydroxy groups in PGS with a long chain carboxylic acid: palmitic acid, one of the most common lipid components. We evaluated two of the resultant palmitate-PGS (PPGS) in this study: one containing 9% palmitate (9-PPGS) and the other16% palmitate (16-PPGS). 16-PPGS grafts had the highest patency. Ultrasound imaging showed that the lumens of 16-PPGS grafts were similar to CCA and smaller than 9-PPGS and PGS grafts 12 weeks post-operation. Immunohistological and histological examination showed an endothelialized lumens in all three types of grafts within 4 weeks. Inflammatory responses to 16-PPGS grafts were limited to the adventitial space in contrast to a more diffusive infiltration in 9-PPGS and PGS grafts in week 4. Examination of calponin+ and αSMA+ cells revealed that 16-PPGS grafts remodeled into a distinctive bi-layered wall, while the walls of 9-PPGS grafts and PGS grafts only had one thick layer of smooth muscle-like cells. Correspondingly, the expression of collagen III and elastin displayed an identical layered structure in the remodeled 16-PPGS grafts, in contrast to a more spread distribution in 9-PPGS and PGS grafts. All the three types of grafts exhibited the same collagen content and burst pressure after 12 weeks of host remodeling. However, the compliance and elastin content of 16-PPGS grafts in week 12 were closest to those of CCA. Overall, placing the degradation of PGS derived elastomer to a window of 4-12 weeks results in vascular conduits closer to arteries in a rat carotid artery interposition model over a 12-week observation period.

Expression of Chitotriosidase in Macrophages Modulates Atherosclerotic Plaque Formation in Hyperlipidemic Mice

Objective

To determine whether overexpression of the chitin degrading enzyme, chitotriosidase (CHIT1), modulates macrophage function and ameliorates atherosclerosis.

Approach and Results

Using a mouse model that conditionally overexpresses CHIT1 in macrophages (CHIT1-Tg) crossbred with the Ldlr ^-/- mouse provided us with a means to investigate the effects of CHIT1 overexpression in the context of atherosclerosis. In vitro, CHIT1 overexpression by murine macrophages enhanced protein expression of IL-4, IL-8, and G-CSF by BMDM upon stimulation with a combination of lipopolysaccharide (LPS) and interferon-γ (IFN-γ). Phosphorylation of ERK1/2 and Akt was also down regulated when exposed to the same inflammatory stimuli. Hyperlipidemic, Ldlr ^-/--CHIT1-Tg (CHIT1-OE) mice were fed a high-fat diet for 12 weeks in order to study CHIT1 overexpression in atherosclerosis. Although plaque size and lesion area were not affected by CHIT1 overexpression in vivo, the content of hyaluronic acid (HA) and collagen within atherosclerotic plaques of CHIT1-OE mice was significantly greater. Localization of both ECM components was markedly different between groups.

Conclusions

These data demonstrate that CHIT1 alters cytokine expression and signaling pathways of classically activated macrophages. In vivo, CHIT1 modifies ECM distribution and content in atherosclerotic plaques, both of which are important therapeutic targets.

Melatonin enhances atherosclerotic plaque stability by inducing prolyl-4-hydroxylase α1 expression

OBJECTIVE

Melatonin, an endogenous neurohormone secreted predominately by the pineal gland, has a variety of physiological functions. However, its protective role in atherosclerosis is not clear. In this study, we sought to investigate the potential effects of melatonin in modulating atherosclerotic plaque stability in apolipoprotein E knockout (ApoE) mice.

METHOD AND RESULTS

Smooth muscle cells were treated with melatonin, which significantly increased mRNA and protein levels of a key intracellular enzyme essential for collagen maturation and secretion, prolyl-4-hydroxylase α1 (P4Hα1). Mechanistically, melatonin increased Akt phosphorylation and transcriptional activation of specificity protein 1 (Sp1), which bound with the P4Hα1 promoter and then induced P4Hα1 expression. Pretreatment with either Akt inhibitor LY294002 or Sp1 inhibitor mithramycin A (MTM) could inhibit melatonin-induced P4Hα1 expression. Finally, atherosclerotic lesions were induced by placing a perivascular collar on the right common carotid artery of ApoE mice, which were received with or without different doses of melatonin or MTM. High-dose melatonin enhanced atherosclerotic plaque stability in ApoE mice in vivo by inducing the expression of P4Hα1, which was reversed by MTM.

CONCLUSION

We propose that melatonin supplementation may provide a novel and promising approach to atherosclerosis treatment.

Extracellular Matrix Proteins and Substrate Stiffness Synergistically Regulate Vascular Smooth Muscle Cell Migration and Cortical Cytoskeleton Organization

Vascular smooth muscle cell (VSMC) migration is a critical step in the progression of cardiovascular disease and aging. Migrating VSMCs encounter a highly heterogeneous environment with the varying extracellular matrix (ECM) composition due to the differential synthesis of collagen and fibronectin (FN) in different regions and greatly changing stiffness, ranging from the soft necrotic core of plaques to hard calcifications within blood vessel walls. In this study, we demonstrate an application of a two-dimensional (2D) model consisting of an elastically tunable polyacrylamide gel of varying stiffness and ECM protein coating to study VSMC migration. This model mimics the in vivo microenvironment that VSMCs experience within a blood vessel wall, which may help identify potential therapeutic targets for the treatment of atherosclerosis. We found that substrate stiffness had differential effects on VSMC migration on type 1 collagen (COL1) and FN-coated substrates. VSMCs on COL1-coated substrates showed significantly diminished migration distance on stiffer substrates, while on FN-coated substrates VSMCs had significantly increased migration distance. In addition, cortical stress fiber orientation increased in VSMCs cultured on more rigid COL1-coated substrates, while decreasing on stiffer FN-coated substrates. On both proteins, a more disorganized cytoskeletal architecture was associated with faster migration. Overall, these results demonstrate that different ECM proteins can cause substrate stiffness to have differential effects on VSMC migration in the progression of cardiovascular diseases and aging.

Glibenclamide ameliorates transplant-induced arteriosclerosis and inhibits macrophage migration and MCP-1 expression

AIMS

Glibenclamide, a diabetes mellitus type 2 medication, has anti-inflammatory and autoimmune properties. This study investigated the effects of glibenclamide on transplant-induced arteriosclerosis as well as the underlying molecular events.

METHODS

Male C57Bl/6 (H-2b) and BALB/c (H-2d) mice were used for aorta transplantation. We used hematoxylin and eosin (HE) and Elastic Van Gieson (EVG) staining for histological assessment, and qRT-PCR and ELISA to measure mRNA and protein levels. Mouse peritoneal macrophages were isolated for lipopolysaccharide (LPS) stimulation and glibenclamide treatment followed by ELISA, Western blot, and Transwell assays.

RESULTS

Glibenclamide inhibited transplant-induced arteriosclerosis in vivo. Morphologically, glibenclamide reduced inflammatory cell accumulation and collagen deposition in the aortas. At the gene level, glibenclamide suppressed aortic cytokine mRNA levels, including interleukin-1β (IL-1β; 10.64 ± 3.19 vs. 23.77 ± 5.72; P < .05), tumor necrosis factor-α (TNF-α; 4.59 ± 0.78 vs. 13.89 ± 5.42; P < .05), and monocyte chemoattractant protein-1 (MCP-1; 202.66 ± 23.44 vs. 1172.73 ± 208.80; P < .01), while IL-1β, TNF-α, and MCP-1 levels were also reduced in the mouse sera two weeks after glibenclamide treatment (IL-1β, 39.40 ± 13.56 ng/ml vs. 78.96 ± 9.39 ng/ml; P < .01; TNF-α, 52.60 ± 13.00 ng/ml vs. 159.73 ± 6.76 ng/ml; P < .01; and MCP-1, 56.60 ± 9.07 ng/ml vs. 223.07 ± 36.28 ng/ml; P < .001). Furthermore, glibenclamide inhibited macrophage expression and secretion of inflammatory factors in vitro through suppressing activation of the nuclear factor-κB (NF-κB) pathway and MCP-1 production.

CONCLUSION

Glibenclamide protected against aorta transplantation-induced arteriosclerosis by reducing inflammatory factors in vivo and inhibited macrophage migration and MCP-1 production in vitro.

Role of smooth muscle cells in coronary artery bypass grafting failure

Atherosclerosis is the underlying pathology of many cardiovascular diseases. The formation and rupture of atherosclerotic plaques in the coronary arteries results in angina and myocardial infarction. Venous coronary artery bypass grafts are designed to reduce the consequences of atherosclerosis in the coronary arteries by diverting blood flow around the atherosclerotic plaques. However, vein grafts suffer a high failure rate due to intimal thickening that occurs as a result of vascular cell injury and activation and can act as 'a soil' for subsequent atherosclerotic plaque formation. A clinically-proven method for the reduction of vein graft intimal thickening and subsequent major adverse clinical events is currently not available. Consequently, a greater understanding of the underlying mechanisms of intimal thickening may be beneficial for the design of future therapies for vein graft failure. Vein grafting induces inflammation and endothelial cell damage and dysfunction, that promotes vascular smooth muscle cell (VSMC) migration, and proliferation. Injury to the wall of the vein as a result of grafting leads to the production of chemoattractants, remodelling of the extracellular matrix and cell-cell contacts; which all contribute to the induction of VSMC migration and proliferation. This review focuses on the role of altered behaviour of VSMCs in the vein graft and some of the factors which critically lead to intimal thickening that pre-disposes the vein graft to further atherosclerosis and re-occurrence of symptoms in the patient.

Seno-destructive smooth muscle cells in the ascending aorta of patients with bicuspid aortic valve disease

Background

Ascending aortic aneurysms constitute an important hazard for individuals with a bicuspid aortic valve (BAV). However, the processes that degrade the aortic wall in BAV disease remain poorly understood.

Methods

We undertook in situ analysis of ascending aortas from 68 patients, seeking potentially damaging cellular senescence cascades. Aortas were assessed for senescence-associated-ß-galactosidase activity, p16^Ink4a and p21 expression, and double-strand DNA breaks. The senescence-associated secretory phenotype (SASP) of cultured-aged BAV aortic smooth muscle cells (SMCs) was evaluated by transcript profiling and consequences probed by combined immunofluorescence and circular polarization microscopy. The contribution of p38 MAPK signaling was assessed by immunostaining and blocking strategies.

Findings

We uncovered SMCs at varying depths of cellular senescence within BAV- and tricuspid aortic valve (TAV)-associated aortic aneurysms. Senescent SMCs were also abundant in non-aneurysmal BAV aortas but not in non-aneurysmal TAV aortas. Multivariable analysis revealed that BAV disease independently associated with SMC senescence. Furthermre, SMC senescence was heightened at the convexity of aortas associated with right-left coronary cusp fusion. Aged BAV SMCs had a pronounced collagenolytic SASP. Moreover, senescent SMCs in the aortic wall were enriched with surface-localized MMP1 and surrounded by weakly birefringent collagen fibrils. The senescent-collagenolytic SMC phenotype depended on p38 MAPK signaling, which was chronically activated in BAV aortas.

Interpretation

We have identified a cellular senescence-collagen destruction axis in at-risk ascending aortas. This novel “seno-destructive” SMC phenotype could open new opportunities for managing BAV aortopathy.

Fund

Canadian Institutes of Health Research, Lawson Health Research Institute, Heart and Stroke Foundation of Ontario/Barnett-Ivey Chair.

Gene therapy with antisense oligonucleotides silencing c-myc reduces neointima formation and vessel wall thickness in a mouse model of vein graft disease

Gene therapy for avoiding intimal hyperplasia of vein grafts after coronary artery bypass grafting is still discussed controversially. A promising application of gene therapy in vein grafts is the use of antisense oligonucleotides to block the expression of genes encoding cell cycle regulatory proteins in vascular smooth muscle cells. C-myc, either directly or by regulating the expression of other proteins, controls cell proliferation, apoptosis and cell survival, tissue remodeling, angiogenesis, cell metabolism, production of inflammatory and anti-inflammatory cytokines, and also participates in cell transformation. Forty C57BL/6J mice underwent interposition of the inferior vena cava from isogenic donor mice into the common carotid artery using a previously described cuff technique. Twenty mice received periadventitial administration of antisense oligonucleotides directed against c-myc (treatment group), the other twenty mice received no treatment (control group). All vein grafts were harvested two weeks after surgery, dehydrated, wax embedded, cut into slides of 2 μm thickness, stained and histologically and immunohistochemically examined under light microscope. In our study, we could show the promising effects of antisense oligonucleotide treatment in a mouse model of vein graft disease including the significant reduction of neointimal, media and total vessel wall thickness with a significantly lower percentage of SMA positive cells, elastic fibres and acid mucopolysaccharides in the neointima and media, a decreased vascularization, and a lower expression of PDGFR ß, MMP-9 and VEGF-A positive cells throughout the whole vein graft wall.

AMPKα inactivation destabilizes atherosclerotic plaque in streptozotocin-induced diabetic mice through AP-2α/miRNA-124 axis

Diabetes mellitus is one of risk factors of cardiovascular diseases including atherosclerosis. Whether and how diabetes promotes the formation of unstable atherosclerotic plaque is not fully understood. Here, we show that streptozotocin-induced type 1 diabetes reduced collagen synthesis, leading to the formation of unstable atherosclerotic plaque induced by collar placement around carotid in apolipoprotein E knockout (Apoe^-/-) mice. These detrimental effects of hyperglycemia on plaque stability were reversed by metformin in vivo without altering the levels of blood glucose and lipids. Mechanistically, we found that high glucose reduced the phosphorylated level of AMP-activated protein kinase alpha (AMPKα) and the transcriptional activity of activator protein 2 alpha (AP-2α), increased the expression of miR-124 expression, and downregulated prolyl-4-hydroxylase alpha 1 (P4Hα1) protein expression and collagen biosynthesis in cultured vascular smooth muscle cells. Importantly, these in vitro effects produced by high glucose were abolished by AMPKα pharmacological activation or adenovirus-mediated AMPKα overexpression. Further, adenovirus-mediated AMPKα gain of function remitted the process of diabetes-induced plaque destabilization in Apoe^-/- mice injected with streptozotocin. Administration of metformin enhanced pAP-2α level, reduced miR-124 expression, and increased P4Hα1 and collagens in carotid atherosclerotic plaque in diabetic Apoe^-/- mice. We conclude that streptozotocin-induced toxic diabetes promotes the formation of unstable atherosclerotic plaques based on the vulnerability index in Apoe^-/- mice, which is related to the inactivation of AMPKα/AP-2α/miRNA-124/P4Hα1 axis. Clinically, targeting AMPKα/AP-2α/miRNA-124/P4Hα1 signaling should be considered to increase the plaque stability in patients with atherosclerosis.

KEY MESSAGES

Hyperglycemia reduced collagen synthesis, leading to the formation of unstable atherosclerotic plaque induced by collar placement around carotid in apolipoprotein E knockout mice. Hyperglycemia destabilizes atherosclerotic plaque in vivo through an AMPKα/AP-2α/miRNA-124/P4Hα1-dependent collagen synthesis. Metformin functions as a stabilizer of atherosclerotic plaque to reduce acute coronary accent.

Cell-based cytotoxicity assays for engineered nanomaterials safety screening: exposure of adipose derived stromal cells to titanium dioxide nanoparticles

BACKGROUND

Increasing production of nanomaterials requires fast and proper assessment of its potential toxicity. Therefore, there is a need to develop new assays that can be performed in vitro, be cost effective, and allow faster screening of engineered nanomaterials (ENMs).

RESULTS

Herein, we report that titanium dioxide (TiO2) nanoparticles (NPs) can induce damage to adipose derived stromal cells (ADSCs) at concentrations which are rated as safe by standard assays such as measuring proliferation, reactive oxygen species (ROS), and lactate dehydrogenase (LDH) levels. Specifically, we demonstrated that low concentrations of TiO2 NPs, at which cellular LDH, ROS, or proliferation profiles were not affected, induced changes in the ADSCs secretory function and differentiation capability. These two functions are essential for ADSCs in wound healing, energy expenditure, and metabolism with serious health implications in vivo.

CONCLUSIONS

We demonstrated that cytotoxicity assays based on specialized cell functions exhibit greater sensitivity and reveal damage induced by ENMs that was not otherwise detected by traditional ROS, LDH, and proliferation assays. For proper toxicological assessment of ENMs standard ROS, LDH, and proliferation assays should be combined with assays that investigate cellular functions relevant to the specific cell type.

Implication of CD38 gene in autophagic degradation of collagen I in mouse coronary arterial myocytes

Collagen deposition is a hallmark of atherosclerosis. Although compromised collagen I degradation has been implied in the pathogenesis of atherosclerosis, the molecular mechanisms are still unclear. Thus, we determined the role of CD38, an enzyme involved in cellular calcium modulation and autophagic flux, in the regulation of collagen I degradation in coronary arterial myocytes (CAMs).In primary cultured CAMs from CD38^-/- mice, collagen I protein accumulation but not mRNA abundance was significantly increased compared with cells from CD38^+/+ mice either under control or upon TGF-Beta stimulation. Pharmacological inhibition of the formation of autophagosomes with 3-methyladenine or of autophagolysosomes with a lysosomal functional blocker, bafilomycin A1, induced a similar increase in collagen protein levels, while inhibition of the proteasome by MG132 had no effects on collagen I accumulation. In addition, CD38-deficiency did not change the protein expression of matrix metalloprotein-9 (MMP-9) or tissue inhibitor of metalloproteinase-1 (TIMP-1) in CAMs. Confocal microscopy showed that collagen I deposition was mainly lied within lysosomes or autophagosomes in CD38^-/- or TGF-Beta treated CAMs. Collagen I deposition increased when CAMs lack CD38 expression or if autophagy was blocked, which is associated with impaired autophagic degradation of collagen I. This CD38 regulation of autophagic flux may represent a novel mechanism for extracellular matrix (ECM) plasticity of coronary arteries upon atherogenic stimulation.

Prelamin A Accumulation Attenuates Rac1 Activity and Increases the Intrinsic Migrational Persistence of Aged Vascular Smooth Muscle Cells

Vascular smooth muscle cell (VSMC) motility is essential during both physiological and pathological vessel remodeling. Although ageing has emerged as a major risk factor in the development of cardiovascular disease, our understanding of the impact of ageing on VSMC motility remains limited. Prelamin A accumulation is known to drive VSMC ageing and we show that presenescent VSMCs, that have accumulated prelamin A, display increased focal adhesion dynamics, augmented migrational velocity/persistence and attenuated Rac1 activity. Importantly, prelamin A accumulation in proliferative VSMCs, induced by depletion of the prelamin A processing enzyme FACE1, recapitulated the focal adhesion, migrational persistence and Rac1 phenotypes observed in presenescent VSMCs. Moreover, lamin A/C-depleted VSMCs also display reduced Rac1 activity, suggesting that prelamin A influences Rac1 activity by interfering with lamin A/C function at the nuclear envelope. Taken together, these data demonstrate that lamin A/C maintains Rac1 activity in VSMCs and prelamin A disrupts lamin A/C function to reduce Rac1 activity and induce migrational persistence during VSMC ageing.

A Real-Time Monitoring System to Assess the Platelet Aggregatory Capacity of Components of a Tissue-Engineered Blood Vessel Wall

Native blood vessels contain both an antiaggregatory intimal layer, which prevents platelet activation in the intact vessel, and a proaggregatory medial layer, which stimulates platelet aggregation upon vascular damage. Yet, current techniques for assessing the functional properties of tissue-engineered blood vessels may not be able to assess the relative effectiveness of both these pro- and antiaggregatory properties of the vessel construct. In this study, we present a novel technique for quantitatively assessing the pro- and antiaggregatory properties of different three-dimensional blood vessel constructs made using a layered fabrication method. This technique utilizes real-time measurements of cytosolic Ca²⁺ signaling to assess platelet activation in fluorescently labeled human platelet suspensions using fluorescence spectrofluorimetry, while also permitting examination of thrombus formation upon the surface of the construct using fluorescent imaging of DiOC₆-labeled platelets. Experiments using this method demonstrated that type I collagen hydrogels, commonly used as scaffolds for vascular tissue engineering, were unable to support significant platelet activation, while type I and III neo-collagen secreted from human coronary artery smooth muscle cells cultured within these hydrogels as the medial layer were able to support thrombus formation. The incorporation of an intimal layer consisting of human umbilical vein endothelial cells on top of the medial layer inhibited platelet activation and aggregation. These data demonstrate that the methodology presented here is able to quantitatively compare the capacity of different constructs to trigger or prevent platelet activation. As such, this technique may provide a useful tool for standardizing the assessment of the functional properties of tissue-engineered blood vessel constructs developed using different culturing techniques.

Endogenous sulfur dioxide alleviates collagen remodeling via inhibiting TGF-β/Smad pathway in vascular smooth muscle cells

The study was designed to investigate the role of endogenous sulfur dioxide (SO₂) in collagen remodeling and its mechanisms in vascular smooth muscle cells (VSMCs). Overexpression of endogenous SO₂ synthase aspartate aminotransferase (AAT) 1 or 2 increased SO₂ levels and inhibited collagen I and III expressions induced by transforming growth factor (TGF)-β1 in VSMCs. In contrast, AAT1 or AAT2 knockdown induced a severe collagen deposition in TGF-β1-treated VSMCs. Furthermore, AAT1 or AAT2 overexpression suppressed procollagen I and III mRNA, upregulated matrix metalloproteinase (MMP)-13 expression, downregulated tissue inhibitors of MMP-1 level, and vice versa. Mechanistically, AAT1 or AAT2 overexpression inhibited phosphorylation of type I TGF-β receptor (TβRI) and Smad2/3 in TGF-β1-stimulated VSMCs. Whereas SB431542, an inhibitor of TGF-β1/Smad signaling pathway, attenuated excessive collagen deposition induced by AAT knockdown. Most importantly, ectopically expressing AAT or exogenous addition of 100 μM SO₂ blocked AAT deficiency-aggravated collagen accumulation in TGF-β1-stimulatd VSMCs, while no inhibition was observed at 100 μM ethyl pyruvate. These findings indicated that endogenous SO₂ alleviated collagen remodeling by controlling TGF-β1/TβRI/Smad2/3-mediated modulation of collagen synthesis and degradation.

Molecular basis and functional significance of Angiotensin II-induced increase in Discoidin Domain Receptor 2 gene expression in cardiac fibroblasts

Delineation of mechanisms underlying the regulation of fibrosis-related genes in the heart is an important clinical goal as cardiac fibrosis is a major cause of myocardial dysfunction. This study probed the regulation of Discoidin Domain Receptor 2 (DDR2) gene expression and the regulatory links between Angiotensin II, DDR2 and collagen in Angiotensin II-stimulated cardiac fibroblasts. Real-time PCR and western blot analyses showed that Angiotensin II enhances DDR2 mRNA and protein expression in rat cardiac fibroblasts via NADPH oxidase-dependent reactive oxygen species induction. NF-κB activation, demonstrated by gel shift assay, abolition of DDR2 expression upon NF-κB inhibition, and luciferase and chromatin immunoprecipitation assays confirmed transcriptional control of DDR2 by NF-κB in Angiotensin II-treated cells. Inhibitors of Phospholipase C and Protein kinase C prevented Angiotensin II-dependent p38 MAPK phosphorylation that in turn blocked NF-κB activation. Angiotensin II also enhanced collagen gene expression. Importantly, the stimulatory effects of Angiotensin II on DDR2 and collagen were inter-dependent as siRNA-mediated silencing of one abolished the other. Angiotensin II promoted ERK1/2 phosphorylation whose inhibition attenuated Angiotensin II-stimulation of collagen but not DDR2. Furthermore, DDR2 knockdown prevented Angiotensin II-induced ERK1/2 phosphorylation, indicating that DDR2-dependent ERK1/2 activation enhances collagen expression in cells exposed to Angiotensin II. DDR2 knockdown was also associated with compromised wound healing response to Angiotensin II. To conclude, Angiotensin II promotes NF-κB activation that up-regulates DDR2 transcription. A reciprocal regulatory relationship between DDR2 and collagen, involving cross-talk between the GPCR and RTK pathways, is central to Angiotensin II-induced increase in collagen expression in cardiac fibroblasts.

Calcium/calmodulin-dependent kinase II inhibition in smooth muscle reduces angiotensin II-induced hypertension by controlling aortic remodeling and baroreceptor function

Background

Multifunctional calcium/calmodulin-dependent kinase II (CaMKII) is activated by angiotensin II (Ang II) in cultured vascular smooth muscle cells (VSMCs), but its function in experimental hypertension has not been explored. The aim of this study was to determine the impact of CaMKII inhibition selectively in VSMCs on Ang II hypertension.

Methods and Results

Transgenic expression of a CaMKII peptide inhibitor in VSMCs (TG SM-CaMKIIN model) reduced the blood pressure response to chronic Ang II infusion. The aortic depressor nerve activity was reset in hypertensive versus normotensive wild-type animals but not in TG SM-CaMKIIN mice, suggesting that changes in baroreceptor activity account for the blood pressure difference between genotypes. Accordingly, aortic pulse wave velocity, a measure of arterial wall stiffness and a determinant of baroreceptor activity, increased in hypertensive versus normotensive wild-type animals but did not change in TG SM-CaMKIIN mice. Moreover, examination of blood pressure and heart rate under ganglionic blockade revealed that VSMC CaMKII inhibition abolished the augmented efferent sympathetic outflow and renal and splanchnic nerve activity in Ang II hypertension. Consequently, we hypothesized that VSMC CaMKII controls baroreceptor activity by modifying arterial wall remodeling in Ang II hypertension. Gene expression analysis in aortas from normotensive and Ang II–infused mice revealed that TG SM-CaMKIIN aortas were protected from Ang II–induced upregulation of genes that control extracellular matrix production, including collagen. VSMC CaMKII inhibition also strongly altered the expression of muscle contractile genes under Ang II.

Conclusions

CaMKII in VSMCs regulates blood pressure under Ang II hypertension by controlling structural gene expression, wall stiffness, and baroreceptor activity.

Collagen inhibitory peptide R1R2 mediates vascular remodeling by decreasing inflammation and smooth muscle cell activation

The extracellular matrix (ECM) is a major constituent of the vessel wall. In addition to providing a structural scaffold, the ECM controls numerous cellular functions in both physiologic and pathologic settings. Vascular remodeling occurs after injury and is characterized by endothelial cell activation, inflammatory cell infiltration, phenotypic modulation of smooth muscle cells (SMCs), and augmented deposition of collagen-rich ECM. R1R2, a peptide derived from the bacterial adhesin SFS, with sequence homology to collagen, is known to inhibit collagen type I deposition in vitro by inhibiting the binding of fibronectin to collagen. However, the inhibitory effects of R1R2 during vascular remodeling have not been explored. We periadventitially delivered R1R2 to carotid arteries using pluronic gel in a vascular remodeling mouse model induced by blood flow cessation, and evaluated its effects on intima-media thickening, ECM deposition, SMC activation, and inflammatory cell infiltration. Morphometric analysis demonstrated that R1R2 reduced intima-media thickening compared to the control groups. R1R2 treatment also decreased collagen type I deposition in the vessel wall, and maintained SMC in the contractile phenotype. Interestingly, R1R2 dramatically reduced inflammatory cell infiltration into the vessel by ∼78%. This decrease was accompanied by decreased VCAM-1 and ICAM-1 expression. Our in vitro studies revealed that R1R2 attenuated SMC proliferation and migration, and also decreased monocyte adhesion and transendothelial migration through endothelial cells. Together, these data suggest that R1R2 attenuates vascular remodeling responses by decreasing inflammation and by modulating SMC proliferation and migration, and suggest that the R1R2 peptide may have therapeutic potential in treating occlusive vascular diseases.

Ethyl-3,4-dihydroxybenzoate with a dual function of induction of osteogenic differentiation and inhibition of osteoclast differentiation for bone tissue engineering

The current approach in biomaterial design of bone implants is to induce in situ regeneration of bone tissue, thus improving integration of the implants and reducing their failure. Therefore, ethyl-3,4-dihydroxybenzoate (EDHB), which stimulates differentiation of osteoblasts and the resultant bone formation, should be studied. In this study, the osteoinductive ability of EDHB in preosteoblasts and human mesenchymal stem cells was examined. EDHB for future use in bone tissue engineering was evaluated by examination of early markers of differentiation (such as alkaline phosphatase [ALP] activity and collagen type I expression) and late markers of osteoblast differentiation (bone nodule formation). As bone remodeling and implant osteointegration depend not only on osteoblast response but also on interaction of the biomaterial with bone-resorbing osteoclasts, differentiation of osteoclasts in response to the compounds was also observed. For in vivo study, alginate gel comprised of EDHB and cells was transplanted into the back subcutis of mice. Our results show that EDHB might have beneficial effects through regulation of both osteoblast and osteoclast differentiation. Therefore, we suggest that EDHB could be a strong candidate for dual regulation to increase osteoblast differentiation and decrease osteoclast differentiation.

Down-regulation of collagen I biosynthesis in intestinal epithelial cells exposed to indomethacin: a comparative proteome analysis

In contrast to accumulated knowledge about gastroduodenal injury associated with nonsteroidal antiinflammatory drugs (NSAIDs) such as indomethacin, small intestinal mucosal injuries have been noticed only recently, and the precise mechanism remains to be elucidated. To clarify the mechanism, we performed 2-DE on IEC-6 rat normal intestinal cells that were treated with indomethacin (200μΜ, 24h) or a vehicle control and identified 18 up-regulated and 8 down-regulated proteins through MALDI-TOF/TOF mass spectrometry. Among these proteins, collagen I and proteins involved in collagen I biosynthesis and maturation, including prolyl 4-hydroxylase subunit α1, protein disulfide isomerase A3 (PDIA3), calreticulin, and endoplasmin, were all down-regulated by indomethacin. Immunohistochemical staining of the intestinal mucosa of indomethacin-administered rats showed a decrease of collagen I on the apical surface of intestinal cells. Cell death induced by indomethacin was prominently suppressed when IEC-6 cells were grown on collagen I-coated plates. cis-4-Hydroxy-l-proline, a proline analog that inhibits collagen synthesis, depressed IEC-6 cell viability in a concentration-dependent manner. Cell death was also induced by short interfering RNA knockdown of endogenous collagen I in IEC-6 cells. In conclusion, by comparative proteome analysis, we identified down-regulation of collagen I as an important mechanism in NSAID-induced intestinal injury.

BIOLOGICAL SIGNIFICANCE

Small intestinal lesions induced by NSAIDs are of great concern in clinical settings. Various hypotheses have been proposed for the origin of these inflammatory responses, such as reduction in the blood flow, intestinal hypermotility, abnormal intestinal mucosal permeability, mitochondrial dysfunction, and reactive oxygen species, many of which are related to the inhibition of prostaglandin synthesis. However, the precise mechanism is yet to be known. The cellular process of the lesions must involve up- and down-regulations of a large number of proteins and complex interactions between them. To elucidate it, global and systematic identification of the proteins in intestinal cells affected by NSAIDs is essential. We found that the proteins exhibiting reduced expression by indomethacin treatment are collagen I and the proteins involved in collagen I synthesis and maturation. Consistent with this, immunohistochemical analysis showed that the indomethacin-treated rat intestinal mucosal cells exhibits decreased collagen I expression on its apical surface. Furthermore, the cell-protective effect of collagen on intestinal mucosal cells was demonstrated by the use of a collagen-synthesis inhibitor, short interfering RNA (siRNA) knockdown of endogenous collagen I, and cell cultivation on collagen I-coated plates versus uncoated plates. These results give important information on the role of the collagen synthesis in intestinal mucosa in the mechanism of NSAID-induced small intestinal lesions.

Cutaneous wound healing after treatment with plant-derived human recombinant collagen flowable gel

Chronic wounds, particularly diabetic ulcers, represent a main public health concern with significant costs. Ulcers often harbor an additional obstacle in the form of tunneled or undermined wounds, requiring treatments that can reach the entire wound tunnel, because bioengineered grafts are typically available only in a sheet form. While collagen is considered a suitable biodegradable scaffold material, it is usually extracted from animal and human cadaveric sources, and accompanied by potential allergic and infectious risks. The purpose of this study was to test the performance of a flowable gel made of human recombinant type I collagen (rhCollagen) produced in transgenic tobacco plants, indicated for the treatment of acute, chronic, and tunneled wounds. The performance of the rhCollagen flowable gel was tested in an acute full-thickness cutaneous wound-healing rat model and compared to saline treatment and two commercial flowable gel control products made of bovine collagen and cadaver human skin collagen. When compared to the three control groups, the rhCollagen-based gel accelerated wound closure and triggered a significant jumpstart to the healing process, accompanied by enhanced re-epithelialization. In a cutaneous full-thickness wound pig model, the rhCollagen-based flowable gel induced accelerated wound healing compared to a commercial product made of bovine tendon collagen. By day 21 post-treatment, 95% wound closure was observed with the rhCollagen product compared to 68% closure in wounds treated with the reference product. Moreover, rhCollagen treatment induced an early angiogenic response and induced a significantly lower inflammatory response than in the control group. In summary, rhCollagen flowable gel proved to be efficacious in animal wound models and is expected to be capable of reducing the healing time of human wounds.

Regulatory T cells prevent plaque disruption in apolipoprotein E-knockout mice

BACKGROUND

CD4(+)CD25(+) regulatory T cells (Tregs) have received considerable interest in atherogenesis. We hypothesized that Tregs treatment may dose-dependently stabilize atherosclerotic plaques by inhibiting inflammatory cytokine secretion and matrix metalloproteinases (MMPs) expression and enhancing P4Hα1 expression in atherosclerotic lesions.

METHODS AND RESULTS

We established a vulnerable carotid plaque model in apolipoprotein E- knockout mice (ApoE-/-). Mice were divided into control, phosphate buffered saline (PBS), small-dose Tregs, moderate-dose Tregs, large-dose Tregs and PC groups. Histopathological analysis showed that the plaque disruption rate was 50%, 50%, 43.8%, 12.5%, 12.5% and 43.8% in the control, PBS, small-dose Tregs, moderate-dose Tregs, large-dose Tregs and PC groups. Tregs treatment resulted in a significant decrease in the relative contents of macrophages and lipids and a substantial increase in those of SMCs and collagen in the carotid plaque, leading to an almost 50% reduction of plaque vulnerability index. Furthermore, Tregs treatment decreased the expression of proinflammatory cytokines, MMP-2 and MMP-9 but increased the expression of P4Hα1 both in vivo and in vitro. Most of these therapeutic effects of Tregs were found to be mediated by transforming growth factor and interleukin-10.

CONCLUSION

Adoptive transfer of Tregs dose-dependently changed plaque composition to a stable plaque phenotype and lowered the incidence of plaque disruption in ApoE-/- mice. The major mechanisms involved reduced expression of inflammatory cytokines and MMP-2 and MMP-9, and enhanced expression of P4Hα1 in the carotid plaque. Tregs may provide a novel approach to the treatment of vulnerable plaques.

Type VIII collagen mediates vessel wall remodeling after arterial injury and fibrous cap formation in atherosclerosis

Collagens in the atherosclerotic plaque signal regulation of cell behavior and provide tensile strength to the fibrous cap. Type VIII collagen, a short-chain collagen, is up-regulated in atherosclerosis; however, little is known about its functions in vivo. We studied the response to arterial injury and the development of atherosclerosis in type VIII collagen knockout mice (Col8(-/-) mice). After wire injury of the femoral artery, Col8(-/-) mice had decreased vessel wall thickening and outward remodeling when compared with Col8(+/+) mice. We discovered that apolipoprotein E (ApoE) is an endogenous repressor of the Col8a1 chain, and, therefore, in ApoE knockout mice, type VIII collagen was up-regulated. Deficiency of type VIII collagen in ApoE(-/-) mice (Col8(-/-);ApoE(-/-)) resulted in development of plaques with thin fibrous caps because of decreased smooth muscle cell migration and proliferation and reduced accumulation of fibrillar type I collagen. In contrast, macrophage accumulation was not affected, and the plaques had large lipid-rich necrotic cores. We conclude that in atherosclerosis, type VIII collagen is up-regulated in the absence of ApoE and functions to increase smooth muscle cell proliferation and migration. This is an important mechanism for formation of a thick fibrous cap to protect the atherosclerotic plaque from rupture.

Fabrication of a multi-layer three-dimensional scaffold with controlled porous micro-architecture for application in small intestine tissue engineering

Various methods can be employed to fabricate scaffolds with characteristics that promote cell-to-material interaction. This report examines the use of a novel technique combining compression molding with particulate leaching to create a unique multi-layered scaffold with differential porosities and pore sizes that provides a high level of control to influence cell behavior. These cell behavioral responses were primarily characterized by bridging and penetration of two cell types (epithelial and smooth muscle cells) on the scaffold in vitro. Larger pore sizes corresponded to an increase in pore penetration, and a decrease in pore bridging. In addition, smaller cells (epithelial) penetrated further into the scaffold than larger cells (smooth muscle cells). In vivo evaluation of a multi-layered scaffold was well tolerated for 75 d in a rodent model. This data shows the ability of the components of multi-layered scaffolds to influence cell behavior, and demonstrates the potential for these scaffolds to promote desired tissue outcomes in vivo.

Urotensin II-induced collagen synthesis in cultured smooth muscle cells from rat aortic media and a possible involvement of transforming growth factor-β1/Smad2/3 signaling pathway

BACKGROUND

Recent studies suggest that urotensin II (UII) and transforming growth factor-β1 (TGF-β1) both have critical roles in vascular remodeling. UII is a recently discovered vasoconstrictive peptide that is involved in the pathogenesis of atherosclerosis, restenosis and hypertension. TGF-β1 is an important factor that has a pivotal role in vascular fibrosis. This study aimed to explore whether TGF-β1 is involved in UII-induced collagen synthesis in rat aortic vascular smooth muscle cells (VSMCs) and examined the effects and mechanisms of UII on collagen synthesis and secretion in VSMCs.

METHODS

VSMCs were prepared by the explant culture method. TGF-β1 and collagen I secretions from the cells were determined by enzyme-linked immunosorbent assay (ELISA). The mRNA and protein expressions of TGF-β1, collagen I, Smad2 and Smad3 were determined using Real-time RT-PCR and Western blotting.

RESULTS

UII dose-dependently promoted TGF-β1 protein expression and secretion from VSMCs, with maximal effect at 10(-8) mol/l at 24 h for protein expression and 10(-7) mol/l at 24 h for protein secretion (both P<0.01). Moreover, UII dose-dependently promoted Smad2 and Smad3 mRNA expression in VSMCs, with maximal effect at 10(-8) mol/l for 12 h (both P<0.01). The effects of UII were significantly inhibited by its receptor antagonists urantide (10(-6) mol/l) or SB-710411 (10(-6) mol/l), and by the mitogen-activated protein kinase (MAPK/ERK) inhibitor PD98059 (10(-6) mol/l). UII dose-dependently promoted collagen I mRNA expression and protein secretion in VSMCs, with maximal effect at 10(-8) mol/l at 12h for mRNA expression and 10(-6) mol/l at 24 h for protein secretion (both P<0.01). Collagen synthesis and secretion from VSMCs induced by UII were inhibited significantly by a TGF-β1-specific neutralizing antibody, SB-431542 (an antagonist of the TGF-β1 type II receptor) and PD98059 (all P<0.01).

CONCLUSIONS

This study suggests that UII could induce collagen synthesis and secretion through upregulation of TGF-β1 expression and secretion in VSMCs, and that TGF-β1/Smad2/3 signaling might be one of the important pathways by which UII is involved in vascular fibrosis.

Intrinsic directionality of migrating vascular smooth muscle cells is regulated by NAD(+) biosynthesis

Cell migration is central to tissue repair and regeneration but must proceed with precise directionality to be productive. Directional migration requires external cues but also depends on the extent to which cells can inherently maintain their direction of crawling. We report that the NAD(+) biosynthetic enzyme, nicotinamide phosphoribosyltransferase (Nampt/PBEF/visfatin), mediates directionally persistent migration of vascular smooth muscle cells (SMCs). Time-lapse microscopy of human SMCs subjected to Nampt inhibition revealed chaotic motility whereas SMCs transduced with the Nampt gene displayed highly linear migration paths. Ordered motility conferred by Nampt was associated with downsizing of the lamellipodium, reduced lamellipodium wandering around the cell perimeter, and increased lamellipodial protrusion rates. These protrusive and polarity-stabilizing effects also enabled spreading SMCs to undergo bipolar elongation to an extent not typically observed in vitro. Nampt was found to localize to lamellipodia and fluorescence recovery of Nampt-eGFP after photobleaching revealed microtubule-dependent transport of Nampt to the leading edge. In addition, Nampt was found to associate with, and activate, Cdc42, and Nampt-driven directional persistence and lamellipodium anchoring required Cdc42. We conclude that high-fidelity SMC motility is coordinated by a Nampt-Cdc42 axis that yields protrusive but small and anchored lamellipodia. This novel, NAD(+)-synthesis-dependent control over motility may be crucial for efficient repair and regeneration of the vasculature, and possibly other tissues.

ETA and ETB receptors are expressed in vascular adventitial fibroblasts

The adventitia has been recognized to play important roles in vascular oxidative stress, remodeling, and contraction. We recently demonstrated that adventitial fibroblasts are able to express endothelin (ET)-1 in response to ANG II. However, it is unclear whether ET-1 receptors are expressed in the adventitia. We therefore investigated the expression and roles of both ET(A) and ET(B) receptors in collagen synthesis and ET-1 clearance in adventitial fibroblasts. Adventitial fibroblasts were isolated and cultured from the mouse thoracic aorta by the explant method. Cultured cells were treated with ANG II (100 nmol/l) or ET-1 (10 pM) in the presence or absence of the ANG II type 1 receptor antagonist losartan (100 μM), the ET-1 receptor antagonists BQ-123 (ET(A) receptor, 1 μM) and BQ-788 (ET(B) receptor, 1 μM), and the ET(B) receptor agonist sarafotoxin 6C (100 nM). ET-1 peptide levels were determined by ELISA, whereas ET(A), ET(B), and collagen levels were determined by Western blot analysis. ANG II increased ET-1 peptide levels in a time-dependent manner. ANG II increased ET(A) and ET(B) receptor protein levels as well as collagen in a similar fashion. ANG II-induced collagen was reduced while in the presence of BQ-123, suggesting a role for the ET(A) receptor in the regulation of the extracellular matrix. ANG II treatment in the presence of BQ-788 significantly increased ET-1 peptide levels. Conversely, the ET(B) receptor agonist sarafotoxin 6C significantly decreased ET-1 peptide levels. These data implicate a role for the ET(B) receptor in the clearance of the ET-1 peptide. In conclusion, both ET(A) and ET(B) receptors are expressed in adventitial fibroblasts, which paves the ground for the biological significance of adventitial ET-1. The ET(A) receptor subtype mediates collagen I expression, whereas the ET(B) receptor subtype may play a protective role through increasing the clearance of the ET-1 peptide.

Type I collagen cleavage is essential for effective fibrotic repair after myocardial infarction

Efficient deposition of type I collagen is fundamental to healing after myocardial infarction. Whether there is also a role for cleavage of type I collagen in infarct healing is unknown. To test this, we undertook coronary artery occlusion in mice with a targeted mutation (Col1a1(r/r)) that yields collagenase-resistant type I collagen. Eleven days after infarction, Col1a1(r/r) mice had a lower mean arterial pressure and peak left ventricular systolic pressure, reduced ventricular systolic function, and worse diastolic function, compared with wild-type littermates. Infarcted Col1a1(r/r) mice also had greater 30-day mortality, larger left ventricular lumens, and thinner infarct walls. Interestingly, the collagen fibril content within infarcts of mutant mice was not increased. However, circular polarization microscopy revealed impaired collagen fibril organization and mechanical testing indicated a predisposition to scar microdisruption. Three-dimensional lattices of collagenase-resistant fibrils underwent cell-mediated contraction, but the fibrils did not organize into birefringent collagen bundles. In addition, time-lapse microscopy revealed that, although cells migrated smoothly on wild-type collagen fibrils, crawling and repositioning on collagenase-resistant collagen was impaired. We conclude that type I collagen cleavage is required for efficient healing of myocardial infarcts and is critical for both dynamic positioning of collagen-producing cells and hierarchical assembly of collagen fibrils. This seemingly paradoxical requirement for collagen cleavage in fibrotic repair should be considered when designing potential strategies to inhibit matrix degradation in cardiac disease.

Adiponectin upregulates prolyl-4-hydroxylase α1 expression in interleukin 6-stimulated human aortic smooth muscle cells by regulating ERK 1/2 and Sp1

Adiponectin is an anti-atherogenic adipokine that inhibits the development of plaque by mechanisms that are not completely understood. Extracellular matrix (ECM) may have a role in the pathogenesis of atherosclerosis. We explored the effect and mechanisms of adiponectin on the synthesis of prolyl-4-hydroxylase (P4H) in interleukin 6 (IL-6)-stimulated human aortic smooth muscle cells (HASMCs). P4Hα1 mRNA level was quantified by RT-PCR, the protein levels of phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2) and P4Hα1 were quantified by western blot analysis, and activation of specific protein 1 (Sp1) was determined by electrophoretic mobility shift assay and subcellular localization of Sp1 by immunofluorescence analysis. Adiponectin significantly increased P4Hα1 mRNA and protein levels in IL-6-stimulated HASMCs in a dose- and time-dependent manner. As well, ERK1/2 and Sp1 played a crucial role in the effect of adiponectin upregulating P4Hα1 expression in IL-6-stimulated HASMCs. Adiponectin abrogated the effects of IL-6 on collagen III level, which may indicate that P4Hα1 is essential for folding the procollagen polypeptide chains into stabilized collagen. Adiponectin attenuates IL-6–inhibited P4Hα1 synthesis and stabilizes collagen formation in HASMCs through a Sp1-ERK1/2-P4Hα1-dependent pathway.

Proteomic changes in articular cartilage of human endemic osteoarthritis in China

Kashin-Beck disease (KBD) is a chronic endemic osteochondropathy with unclear pathogenesis. It is a degenerative disease similar to osteoarthritis, but with different manifestations of cartilage damage. The aim of this investigation was to show the protein changes in KBD cartilage and to identify the candidate proteins in order to understand the pathogenesis of the disease. Proteins were extracted from the media of primary cell cultures of KBD and normal chondrocytes, and separated by two-dimensional fluorescence difference gel electrophoresis (2-D DIGE). MALDI-TOF/TOF analysis revealed statistically significant differences in 27 proteins from KBD chondrocyte cultures, which consisted of 17 up-regulated and ten down-regulated proteins. The results were further validated by Western blot analysis. The proteins identified are mainly involved in cellular redox homeostasis and stress response (MnSOD, Hsp27, Peroxiredoxin-1, and Cofilin-1), glycolysis (PGK-1, PGM-1, α-enolase), and cell motility and cytoskeletal organization (Actin, Calponin-2, and Keratin). These KBD-associated proteins indicate that cytoskeletal remodeling, glycometabolism, and oxidative stress are abnormal in KBD articular cartilage.

Genetic polymorphisms and plasma levels of matrix metalloproteinases and their relationships with developing acute myocardial infarction

OBJECTIVES

Matrix metalloproteinases (MMPs) play an important role in early atherosclerosis, plaque rupture, extracellular matrix remodeling, and myocardial infarction (MI). MMP gene polymorphisms contribute to the risk of developing cardiovascular disease. We designed to investigate the association of acute MI (AMI) with a polymorphism in the human MMP-1, 2, 3, and 9 genes in Iranian patients with AMI.

METHODS

Genomic DNA of 400 enrolled patients with AMI and 200 controls was extracted from their blood samples. The -1607 1G/2G MMP-1, -1306 C/T MMP-2, -1171 5A/6A MMP-3, -1562 C/T MMP-9 polymorphisms were detected. Plasma levels of MMPs were analyzed.

RESULTS

There are significant differences in MMP-3 '5A' allele and genotype in the patients with AMI comparing with controls. However, no significant differences were observed in MMP-1, 2, and 9 allele frequencies between the patients and controls. Differences between plasma levels of MMPs were significant in the patients than in controls. There were statistically significant differences between plasma MMP-3 in carriers of 5A allele compared with 6A allele. MMP-9 plasma levels were significantly higher in the carriers of -1306 TT and -1306 CT than CC. However, there were no statistically significant association between genetic variation of MMP-1, 2, and 3 in the patients and their plasma levels.

CONCLUSION

These data suggest that MMP genotyping such as genetic polymorphism in MMP-3 might be helpful in determining susceptibility to AMI in Iranian patients. In addition, susceptibility to AMI might be related to MMP-9 gene expression, which affects its plasma levels.

Isolation, culture, and characterization of smooth muscle cells from human intracranial aneurysms

BACKGROUND

Smooth muscle cells (SMCs) play a critical role in the vascular wall and also participate in vascular repair mechanisms. Dysfunction of SMCs may also contribute to the formation of intracranial aneurysms (IAs) causing subarachnoid hemorrhage. Our aim was to investigate the possibility of using cultured SMCs as an in vitro model for the study of aneurysmal SMCs.

METHODS

IA tissue was obtained during microsurgical ligation of IAs. By using the explant method, cell cultures were established from the aneurysmal tissue. The phenotype of cultured cells from passage to passage was studied using immunoperoxidase staining and Western blotting. Eight cell lines could be established from 29 IA samples. Four lines showing most rigorous growth were investigated more thoroughly.

RESULTS

Abundant expression of SMC markers, α-smooth muscle cell actin and calponin, as well as of prolyl-4-hydroxylases, a key enzyme family in the synthesis of collagens, was observed in all of them. Aneurysmal SMCs in culture maintained their phenotype and SMC characteristics through the early passages of growth.

CONCLUSION

This is the first documented successful culture of SMCs from human IAs. An access to living human cells of aneurysmal origin gives us a new tool in our research of the formation, growth, and rupture of IAs.

Interleukin-6: a potential target for post-thrombotic syndrome

BACKGROUND

Deep vein thrombosis (DVT) and its associated sequelae, post-thrombotic syndrome (PTS), are significant health care problems in the United States. It is estimated that a maximum of 60% of patients diagnosed with DVT develop PTS, which is characterized by extensive perivenous and mural fibrosis. Interleukin-6 (IL-6) has been linked to fibrosis, and high circulating plasma levels have been found to increase the risk of developing DVT. The aim of this study was to elucidate the role of IL-6 in the progression of vein wall fibrosis by using a mouse model of DVT.

METHODS AND RESULTS

C57BL/6 mice (n = 136) were treated with either anti-IL-6 monoclonal antibody or control rat-immunoglobulin G. Thrombus was induced by using an inferior vena cava ligation model. The inferior vena cava and thrombus were harvested at days 2, 6, or 14 for thrombus weight, gene expression of IL-6 and/or C-C motif chemokine ligand 2 (CCL2), inflammatory cell recruitment, and morphometric analysis of vein wall fibrosis. Mice treated with anti-IL-6 had smaller thrombus weights at day 2, decreased vein wall gene expression and protein concentration of CCL2 at day 2, and impaired vein wall influx of monocytes from days 2 to 6, as compared with controls. Intimal thickness was reduced by 44% (p < 0.05) and vein wall collagen deposition was decreased by 30% at day 14 in the anti-IL-6 group (p < 0.05).

CONCLUSIONS

Neutralizing IL-6 throughout venous thrombogenesis decreased the production of CCL2, reduced monocyte recruitment, and decreased vein wall intimal thickness and fibrosis. These results suggest that IL-6 may serve as a therapeutic target to prevent the fibrotic complications seen in PTS.