Novel mechanisms of valsartan on the treatment of acute myocardial infarction through inhibition of the antiadhesion molecule periostin

The role of periostin in cardiac fibrosis

Cardiac fibrosis, which is the buildup of proteins in the connective tissues of the heart, can lead to end-stage extracellular matrix (ECM) remodeling and ultimately heart failure. Cardiac remodeling involves changes in gene expression in cardiac cells and ECM, which significantly leads to the morbidity and mortality in heart failure. However, despite extensive research, the elusive intricacies underlying cardiac fibrosis remain unidentified. Periostin, an extracellular matrix (ECM) protein of the fasciclin superfamily, acts as a scaffold for building complex architectures in the ECM, which improves intermolecular interactions and augments the mechanical properties of connective tissues. Recent research has shown that periostin not only contributes to normal ECM homeostasis in a healthy heart but also serves as a potent inducible regulator of cellular reorganization in cardiac fibrosis. Here, we reviewed the constitutive domain of periostin and its interaction with other ECM proteins. We have also discussed the critical pathophysiological functions of periostin in cardiac remodeling mechanisms, including two distinct yet potentially intertwined mechanisms. Furthermore, we will focus on the intrinsic complexities within periostin research, particularly surrounding the contentious issues observed in experimental findings.

Periostin increased by mechanical stress upregulates interleukin-6 expression in the ligamentum flavum

Ligamentum flavum (LF) hypertrophy is a major cause of lumbar spinal canal stenosis. Although mechanical stress is thought to be a major factor involved in LF hypertrophy, the exact mechanism by which it causes hypertrophy has not yet been fully elucidated. Here, changes in gene expression due to long-term mechanical stress were analyzed using RNA-seq in a rabbit LF hypertrophy model. In combination with previously reported analysis results, periostin was identified as a molecule whose expression fluctuates due to mechanical stress. The expression and function of periostin were further investigated using human LF tissues and primary LF cell cultures. Periostin was abundantly expressed in human hypertrophied LF tissues, and periostin gene expression was significantly correlated with LF thickness. In vitro, mechanical stress increased gene expressions of periostin, transforming growth factor-β1, α-smooth muscle actin, collagen type 1 alpha 1, and interleukin-6 (IL-6) in LF cells. Periostin blockade suppressed the mechanical stress-induced gene expression of IL-6 while periostin treatment increased IL-6 gene expression. Our results suggest that periostin is upregulated by mechanical stress and promotes inflammation by upregulating IL-6 expression, which leads to LF degeneration and hypertrophy. Periostin may be a pivotal molecule for LF hypertrophy and a promising therapeutic target for lumbar spinal stenosis.

Periostin Short Fragment with Exon 17 via Aberrant Alternative Splicing Is Required for Breast Cancer Growth and Metastasis

BACKGROUND

Periostin (POSTN) is a 93 kDa matrix protein that helps to regulate collagen gene expression in the extracellular matrix. POSTN overexpression is a prognostic factor in malignant cancers; however, some researchers have observed it in the stroma, whereas others have reported it on tumors.

OBJECTIVE

This study aimed to investigate the function of POSTN on tumors.

METHODS AND RESULTS

We found that POSTN in cancer cells can be detected by using an antibody against the POSTN C-terminal region exon 17 (Ex17 antibody), but not with an antibody against the POSTN N-terminal region exon 12 (Ex12 antibody) in patients with breast cancer. In a fraction secreted from fibroblasts, LC-MS/MS analysis revealed a short fragment of POSTN of approximately 40 kDa with exon 17. In addition, molecular interaction analysis showed that POSTN with exon 17, but not POSTN without exon 17, bound specifically to wnt3a, and the Ex17 antibody inhibited the binding.

CONCLUSION

A short fragment of POSTN with exon 17, which originates in the fibroblasts, is transported to cancer cells, whereas POSTN fragments without exon 17 are retained in the stroma. The Ex17 antibody inhibits the binding between POSTN exon 17 and wnt3a.

Heterogeneity of Intestinal Tissue Eosinophils: Potential Considerations for Next-Generation Eosinophil-Targeting Strategies

Eosinophils are implicated in the pathophysiology of a spectrum of eosinophil-associated diseases, including gastrointestinal eosinophilic diseases (EGIDs). Biologics that target the IL-5 pathway and are intended to ablate eosinophils have proved beneficial in severe eosinophilic asthma and may offer promise in treating some endotypes of EGIDs. However, destructive effector functions of eosinophils are only one side of the coin; eosinophils also play important roles in immune and tissue homeostasis. A growing body of data suggest tissue eosinophils represent a plastic and heterogeneous population of functional sub-phenotypes, shaped by environmental (systemic and local) pressures, which may differentially impact disease outcomes. This may be particularly relevant to the GI tract, wherein the highest density of eosinophils reside in the steady state, resident immune cells are exposed to an especially broad range of external and internal environmental pressures, and greater eosinophil longevity may uniquely enrich for co-expression of eosinophil sub-phenotypes. Here we review the growing evidence for functional sub-phenotypes of intestinal tissue eosinophils, with emphasis on the multifactorial pressures that shape and diversify eosinophil identity and potential targets to inform next-generation eosinophil-targeting strategies designed to restrain inflammatory eosinophil functions while sustaining homeostatic roles.

RAS inhibition in resident fibroblast biology

Angiotensin II (Ang II) is a primary mediator of profibrotic signaling in the heart and more specifically, the cardiac fibroblast. Ang II-mediated cardiomyocyte hypertrophy in combination with cardiac fibroblast proliferation, activation, and extracellular matrix production compromise cardiac function and increase mortality in humans. Profibrotic actions of Ang II are mediated by increasing production of fibrogenic mediators (e.g. transforming growth factor beta, scleraxis, osteopontin, and periostin), recruitment of immune cells, and via increased reactive oxygen species generation. Drugs that inhibit Ang II production or action, collectively referred to as renin angiotensin system (RAS) inhibitors, are first line therapeutics for heart failure. Moreover, transient RAS inhibition has been found to persistently alter hypertensive cardiac fibroblast responses to injury providing a useful tool to identify novel therapeutic targets. This review summarizes the profibrotic actions of Ang II and the known impact of RAS inhibition on cardiac fibroblast phenotype and cardiac remodeling.

Molecular Signatures of Sinus Node Dysfunction Induce Structural Remodeling in the Right Atrial Tissue

The sinus node (SN) is located at the apex of the cardiac conduction system, and SN dysfunction (SND)-characterized by electrical remodeling-is generally attributed to idiopathic fibrosis or ischemic injuries in the SN. SND is associated with increased risk of cardiovascular disorders, including syncope, heart failure, and atrial arrhythmias, particularly atrial fibrillation. One of the histological SND hallmarks is degenerative atrial remodeling that is associated with conduction abnormalities and increased right atrial refractoriness. Although SND is frequently accompanied by increased fibrosis in the right atrium (RA), its molecular basis still remains elusive. Therefore, we investigated whether SND can induce significant molecular changes that account for the structural remodeling of RA. Towards this, we employed a rabbit model of experimental SND, and then compared the genome-wide RNA expression profiles in RA between SND-induced rabbits and sham-operated controls to identify the differentially expressed transcripts. The accompanying gene enrichment analysis revealed extensive pro-fibrotic changes within 7 days after the SN ablation, including activation of transforming growth factor-β (TGF-β) signaling and alterations in the levels of extracellular matrix components and their regulators. Importantly, our findings suggest that periostin, a matricellular factor that regulates the development of cardiac tissue, might play a key role in mediating TGF-β-signaling-induced aberrant atrial remodeling. In conclusion, the present study provides valuable information regarding the molecular signatures underlying SND-induced atrial remodeling, and indicates that periostin can be potentially used in the diagnosis of fibroproliferative cardiac dysfunctions.

[Gerontology Issues in Cardiology Practice]

Increase in life expectancy during the second part of the 20th century is accompanied by increase in proportion of elderly and senile age population. However, despite the increase in life expectancy, the prevalence of most chronic diseases and functional impairments rises with age. Elderly and senile age is associated with the risk of cardiovascular diseases (CVD), therefore the problem of managing elderly patients with CVD becomes especially urgent.

Cardioprotective mechanisms of salvianic acid A sodium in rats with myocardial infarction based on proteome and transcriptome analysis

Ischemic heart diseases (IHDs) cause great morbidity and mortality worldwide, necessitating effective treatment. Salvianic acid A sodium (SAAS) is an active compound derived from the well-known herbal medicine Danshen, which has been widely used for clinical treatment of cardiovascular diseases in China. This study aimed to confirm the cardioprotective effects of SAAS in rats with myocardial infarction and to investigate the underlying molecular mechanisms based on proteome and transcriptome profiling of myocardial tissue. The results showed that SAAS effectively protected against myocardial injury and improved cardiac function. The differentially expressed proteins and genes included important structural molecules, receptors, transcription factors, and cofactors. Functional enrichment analysis indicated that SAAS participated in the regulation of actin cytoskeleton, phagosome, focal adhesion, tight junction, apoptosis, MAPK signaling, and Wnt signaling pathways, which are closely related to cardiovascular diseases. SAAS may exert its cardioprotective effect by targeting multiple pathways at both the proteome and transcriptome levels. This study has provided not only new insights into the pathogenesis of myocardial infarction but also a road map of the cardioprotective molecular mechanisms of SAAS, which may provide pharmacological evidence to aid in its clinical application.

Periostin as a novel biomarker of cardiovascular disease: A systematic evidence landscape of preclinical and clinical studies

BACKGROUND

Periostin is a matricellular protein, expressed in various normal adult and fetal tissues. Recently, elevated periostin levels have been reported in heart failure, coronary artery disease, and stroke. However, there is lack of clinical studies to clarify the prognostic significance of systemic periostin levels in cardiovascular diseases (CVDs). The aim of the study was to perform a systematic review of published evidence on periostin and CVDs, and to clarify the diagnostic and prognostic significance of systemic periostin levels in CVDs.

METHODS

A systematic search on PubMed was performed to identify relevant articles from inception to December 2018. The eligible studies evaluating the periostin expression and periostin levels in animal and human studies.

RESULTS

A total of 24 relevant studies, including both animal and human data, were included. Periostin is significantly observed in myocardium tissue of failing hearts compared with control, and is also expressed in atherosclerotic plaques. Systemic periostin levels were significantly correlated with cardiac function and severity of CVD in several studies. A clinical study also observed positive correlation between periostin and N-terminal pro b-type natriuretic peptide (NT-proBNP), highly sensitive troponin (hsTnT), and ST2 cardiac biomarker. Studies reported limited adjustment for potential confounders.

CONCLUSIONS

The evidence of current review support potential role of periostin in the pathophysiology of CVD. However, scarcity of data regarding the clinical use of periostin levels in the current management of CVDs further creates room for the future investigation. Therefore, further studies warrant to clarify its potential role, if any, as a novel cardiac biomarker.

Periostin and Inflammatory Disease: Implications for Chronic Rhinosinusitis

OBJECTIVE

To provide a comprehensive overview of the emerging role of periostin, an extracellular matrix protein, as a key component in the development, diagnosis, and treatment of patients with chronic rhinosinusitis.

DATA SOURCES

Medline database.

REVIEW METHODS

A state of the art review was performed targeting English-language studies investigating the role of periostin in cardiopulmonary, neoplastic, and inflammatory diseases, with emphasis on recent advances in the study of periostin in chronic rhinosinusitis.

CONCLUSIONS

Periostin has emerged as a novel biomarker and therapeutic target for numerous human pathologies, including cardiac, pulmonary, and neoplastic disease. The upregulation of periostin in chronic rhinosinusitis suggests the potential for similar roles among patients with sinonasal disease.

IMPLICATIONS FOR PRACTICE

Chronic rhinosinusitis is a widespread disease with major clinical and societal impact. A critical limitation in the current treatment of patients with chronic rhinosinusitis is the absence of clinically relevant biomarkers to guide diagnosis and treatment selection. A review of the literature supports a likely role of periostin as a biomarker of chronic rhinosinusitis, as well as a novel therapeutic target in the future treatment of patients with sinonasal disease.

Vitamin K‑dependent proteins involved in bone and cardiovascular health (Review)

In postmenopausal women and elderly men, bone density decreases with age and vascular calcification is aggravated. This condition is closely associated with vitamin K2 deficiency. A total of 17 different vitamin K-dependent proteins have been identified to date. Vitamin K-dependent proteins are located within the bone, heart and blood vessels. For instance, carboxylated osteocalcin is beneficial for bone and aids the deposition of calcium into the bone matrix. Carboxylated matrix Gla protein effectively protects blood vessels and may prevent calcification within the vascular wall. Furthermore, carboxylated Gla-rich protein has been reported to act as an inhibitor in the calcification of the cardiovascular system, while growth arrest-specific protein-6 protects endothelial cells and vascular smooth muscle cells, resists apoptosis and inhibits the calcification of blood vessels by inhibiting the apoptosis of vascular smooth muscle cells. In addition, periostin may promote the differentiation, aggregation, adhesion and proliferation of osteoblasts. Periostin also occurs in the heart and may be associated with the reconstruction of heart function. These vitamin K-dependent proteins may exert their functions following γ-carboxylation with vitamin K, and different vitamin K-dependent proteins may exhibit synergistic effects or antagonistic effects on each other. In the cardiovascular system with vitamin K antagonist supplement or vitamin K deficiency, calcification occurs in the endothelium of blood vessels and vascular smooth muscle cells are transformed into osteoblast-like cells, a phenomenon that resembles bone growth. Both the bone and cardiovascular system are closely associated during embryonic development. Thus, the present study hypothesized that embryonic developmental position and tissue calcification may have a certain association for the bone and the cardiovascular system. This review describes and briefly discusses several important vitamin K-dependent proteins that serve an important role in bone and the cardiovascular system. The results of the review suggest that the vascular calcification and osteogenic differentiation of vascular smooth muscle cells may be associated with the location of the bone and cardiovascular system during embryonic development.

Extracellular matrix remodeling and cardiac fibrosis

Cardiac fibrosis, characterized by excessive deposition of extracellular matrix (ECM) proteins in the myocardium, distorts the architecture of the myocardium, facilitates the progression of arrhythmia and cardiac dysfunction, and influences the clinical course and outcome in patients with heart failure. This review describes the composition and homeostasis in normal cardiac interstitial matrix and introduces cellular and molecular mechanisms involved in cardiac fibrosis. We also characterize the ECM alteration in the fibrotic response under diverse cardiac pathological conditions and depict the role of matricellular proteins in the pathogenesis of cardiac fibrosis. Moreover, the diagnosis of cardiac fibrosis based on imaging and biomarker detection and the therapeutic strategies are addressed. Understanding the comprehensive molecules and pathways involved in ECM homeostasis and remodeling may provide important novel potential targets for preventing and treating cardiac fibrosis.

Periostin in cardiovascular disease and development: a tale of two distinct roles

Tissue development and homeostasis are dependent upon the concerted synthesis, maintenance, and degradation of extracellular matrix (ECM) molecules. Cardiac fibrosis is now recognized as a primary contributor to incidence of heart failure, particularly heart failure with preserved ejection fraction, wherein cardiac filling in diastole is compromised. Periostin is a cell-associated protein involved in cell fate determination, proliferation, tumorigenesis, and inflammatory responses. As a non-structural component of the ECM, secreted 90 kDa periostin is emerging as an important matricellular factor in cardiac mesenchymal tissue development. In addition, periostin's role as a mediator in cell-matrix crosstalk has also garnered attention for its association with fibroproliferative diseases in the myocardium, and for its association with TGF-β/BMP signaling. This review summarizes the phylogenetic history of periostin, its role in cardiac development, and the major signaling pathways influencing its expression in cardiovascular pathology. Further, we provide a synthesis of the current literature to distinguish the multiple roles of periostin in cardiac health, development and disease. As periostin may be targeted for therapeutic treatment of cardiac fibrosis, these insights may shed light on the putative timing for application of periostin-specific therapies.

Periostin as a Biomarker for Nasal Polyps in Chronic Rhinosinusitis

Objective Periostin is an extracellular matrix protein that is elevated in the sinonasal tissues of patients with chronic rhinosinusitis (CRS). The purpose of this study was to determine whether serum periostin could serve as a molecular biomarker of nasal polyp burden in sinonasal disease. Study Design Prospective cohort study. Setting Academic medical center. Subjects and Methods Serum periostin levels were measured by ELISA on blood samples collected from patients undergoing sinus surgery for CRS (n = 71), further stratified by phenotype as defined by nasal polyps and asthma. Results were compared with assays performed on control subjects (n = 62). Results Mean serum periostin levels were markedly elevated in patients with CRS versus controls (66.1 ng/mL [95% CI, 51.6-80.6] vs 38.7 ng/mL [95% CI, 34.4-42.9], respectively, P = .004). In addition, mean periostin levels were significantly higher in CRS patients with nasal polyps as compared with those without polyps (94.8 ng/mL [95% CI, 67.3-122.4] vs 41.1 ng/mL [95% CI, 35.2-47.0], respectively, P < .001). Periostin levels did not correlate with sex ( P = .473), smoking history ( P = .748), aspirin-exacerbated respiratory disease status ( P = .136), oral steroid use within 1 month of surgery ( P = .281), use of topical steroid nasal spray ( P = .864), or number of prior sinus operations ( P = .973). Conclusion Serum periostin appears to be a novel molecular biomarker for the presence of nasal polyps and may serve as an indicator of CRS endotypes.

Periostin cross‑reacts with the renin‑angiotensin system during liver fibrosis development

Periostin is a 90-kDa extracellular matrix protein, which is secreted primarily from fibroblasts and is expressed in the lungs, kidneys and heart valves. Angiotensin II (AT-II) serves pivotal roles in the pathogenesis of several diseases with accompanying fibrosis, including chronic liver diseases. AT-II induces periostin expression by regulating transforming growth factor-β1 (TGF-β1)/Smad signaling during cardiac fibrosis. The aim of the present study was to investigate the interaction between AT-II and periostin during liver fibrosis development. Fischer 344 rats were fed a choline-deficient L-amino-acid (CDAA)-defined diet for 12 weeks to simulate the development of steatohepatitis with liver fibrosis. Losartan, an AT-II type I receptor blocker, was administered to inhibit the effect of AT-II. The therapeutic effect of losartan on hepatic fibrosis development and on periostin expression was then evaluated. Several in vitro experiments were performed to examine the mechanisms underlying the interaction between AT-II and periostin in activated hepatic stellate cells (Ac-HSCs). Treatment with losartan suppressed the development of liver fibrosis induced by the CDAA diet, and reduced hepatic periostin expression. In addition, losartan treatment suppressed hepatic Ac-HSC expansion and hepatic TGF-β1 expression. In vitro analysis using LX2 HSC cells indicated that AT-II can augment TGF-β1 and collagen type I α1 mRNA expression via periostin expression, suggesting that the interaction between AT-II and periostin may serve a role in liver fibrosis development. In conclusion, blockade of AT-II-induced periostin may suppress the progression of liver fibrosis development.

The Impact of Angiotensin-Modulating Antihypertensives on Time Interval to Revision Surgery for Nasal Polyps

OBJECTIVE/HYPOTHESIS

Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) have been shown to suppress expression of periostin, a matricellular protein that is markedly elevated in nasal polyp tissue. The purpose of this study was to determine whether use of these antihypertensive agents affects the time to revision sinus surgery in patients with polyp regrowth.

STUDY DESIGN

Case series with chart review.

SETTING

Academic medical center.

SUBJECTS AND METHODS

Records were reviewed for 330 patients who underwent ≥2 operations for chronic sinusitis with nasal polyps from April 1987 through August 2015. The time between surgical interventions was compared with patient demographics and clinical characteristics, including use of ACEIs and ARBs.

RESULTS

Sixty patients were taking ACEIs or ARBs during the study period, of which 32 had concurrent asthma. The mean interval between polyp operations was 61.0 ± 45.2 months (range, 2-228.6 months). Among patients with asthma (n = 197), the mean time to revision surgery was prolonged by >2 years for those taking ACEIs or ARBs (81.0 vs 54.5 months, P = .006). A similar impact on time to revision surgery was not observed for nonasthmatics taking these medications (61.0 vs 65.2 months, P = .655).

CONCLUSION

Use of ACEIs and ARBs is associated with an increased time to revision sinus surgery among patients with concurrent nasal polyps and asthma. A possible mechanism of this observed effect is suppression of periostin expression through inhibition of the angiotensin pathway.

Selective Blockade of Periostin Exon 17 Preserves Cardiac Performance in Acute Myocardial Infarction

We previously reported that overexpression of full-length periostin, Pn-1, resulted in ventricular dilation with enhanced interstitial collagen deposition in a rat model. However, other reports have documented that the short-form splice variants Pn-2 (lacking exon 17) and Pn-4 (lacking exons 17 and 21) promoted cardiac repair by angiogenesis and prevented cardiac rupture after acute myocardial infarction. The apparently differing findings from those reports prompted us to use a neutralizing antibody to selectively inhibit Pn-1 by blockade of exon 17 in a rat acute myocardial infarction model. Administration of Pn neutralizing antibody resulted in a significant decrease in the infarcted and fibrotic areas of the myocardium, which prevented ventricular wall thinning and dilatation. The inhibition of fibrosis by Pn neutralizing antibody was associated with a significant decrease in gene expression of fibrotic markers, including collagen I, collagen III, and transforming growth factor-β1. Importantly, the number of α-smooth muscle actin-positive myofibroblasts was significantly reduced in the hearts of animals treated with Pn neutralizing antibody, whereas cardiomyocyte proliferation and angiogenesis were comparable in the IgG and neutralizing antibody groups. Moreover, the level of Pn-1 expression was significantly correlated with the severity of myocardial infarction. In addition, Pn-1, but not Pn-2 or Pn-4, inhibited fibroblast and myocyte attachment, which might account for the cell slippage observed during cardiac remodeling. Collectively, these results indicate that therapeutics that specifically inhibit Pn exon-17, via a neutralizing antibody or drug, without suppressing other periostin variants might offer a new class of medication for the treatment of acute myocardial infarction patients.

Elevated expression of periostin in diabetic cardiomyopathy and the effect of valsartan

Background

Periostin, an extracellular matrix protein, plays a significant role in adverse cardiac remodeling. However, no report has documented the function of periostin in left ventricular remodeling of streptozototin (STZ)-induced diabetic rats. The aim of the present study was to observe the expression of periostin in Wistar rat’s myocardium of diabetic cardiomyopathy (DCM) and the effect of valsartan on it.

Methods

Immunohistochemistry, real-time polymerase chain reaction, and Western blot analysis were used to determine the degree of expression and location of periostin, transforming growth factor (TGF)-β1, TGF-β1 type II receptor (TGF-β1 R II), and Type I and III collagens in the myocardium of STZ-induced diabetic rats.

Results

Periostin, TGF-β1, TGF-β1 R II, and Type I and III collagens were significantly increased in the myocardium of diabetic rats compared with control group on both messenger ribonucleic acid and protein levels. In addition, diabetic rats treated with valsartan could have reduced expression of periostin and improved cardiac remodeling of DCM.

Conclusions

Periostin may play a crucial role in cardiac remodeling and myocardial interstitial fibrosis process of DCM and it could be one of the important mechanisms for valsartan to improve the ventricular remodeling of DCM.

Searching novel diagnostic markers and targets for therapy of CKD

Over the last decade, identification and characterization of novel markers of progression and targets for therapy of chronic kidney disease (CKD) have been challenging for the research community. Several promising candidates have emerged, mainly from experimental models of CKD that are yet to be investigated in clinical studies. The authors identified two candidate genes: periostin, an extracellular matrix protein involved in bone and dental development, and the discoidin domain receptor 1 (DDR1), a collagen-binding membrane receptor with tyrosine kinase activity. Both genes are inactive in adulthood under normal conditions but have been shown to be highly inducible following injury to glomerular or tubular epithelial cells. The objective of this review is to summarize recent evidence supporting the role of periostin and DDR1 as potential novel biomarkers and therapeutic targets in CKD.

Periostin and receptor activator of nuclear factor κ-B ligand expression in allergic fungal rhinosinusitis

BACKGROUND

Allergic fungal rhinosinusitis (AFRS) is a disease demonstrating substantial eosinophilic inflammation and characteristic radiographic bony erosion/expansion. Periostin is an extracellular matrix protein associated with eosinophil accumulation in eosinophilic esophagitis, allergic asthma mucus production, and chronic rhinosinusitis (CRS) polyp formation. Receptor activator of nuclear factor κ-B ligand (RANKL) is an osteoclast activator present in osteoporosis and periodontal disease. We sought to evaluate periostin and RANKL expression in AFRS and correlate these levels with radiographic scales of disease severity.

METHODS

Thirty sinus tissue specimens were intraoperatively collected from 3 patient groups: AFRS; CRS without nasal polyps (CRSsNP); and controls (n = 10 per group). Specimens were analyzed by semiquantitative reverse-transcription polymerase chain reaction (sq-RT-PCR) and immunofluorescence (IF) labeling/confocal microscopy for the presence of both periostin and RANKL. Immunofluorescence staining intensity was quantified by pixel density analysis. Preoperative computed tomography (CT) scans from each patient were scored using both the Lund-Mackay and CT bone erosion scoring systems.

RESULTS

Periostin was significantly elevated in AFRS sinus tissue compared to CRSsNP and controls, as demonstrated by IF (p < 0.001) and PCR (p = 0.011). RANKL was not detected in sinus tissue by IF or PCR. Periostin levels positively correlated with radiographic indices of disease severity for both soft tissue and bone, using Lund-Mackay (r = 0.926 [PCR] and r = 0.581 [IF]) and CT bone erosion (r = 0.672 [PCR] and r = 0.616 [IF]) scoring systems, respectively.

CONCLUSION

Periostin is increased in AFRS tissue compared to CRSsNP and controls. Periostin levels positively correlate with radiologic disease severity scores. The increased levels of periostin in AFRS are possibly tied to its intense eosinophilic inflammatory etiology.

Ageing related periostin expression increase from cardiac fibroblasts promotes cardiomyocytes senescent

Periostin, as an extracellular matrix (ECM) protein, plays a critical role in myocardial fibrosis and also might be involved in the heart inflammatory process since it is a downstream molecule of IL4 and IL13. Considering the possible important role of periostin in heart aging, this study explored periostin expression pattern in both rat and human, the effect of periostin expression on cardiomyocyte senescent and expression of three cytokines (IL13, IL4 and IL6) in different age groups of human. This study found heart aging is associated with increased expression of periostin from cardiac fibroblasts and serum inflammatory cytokines (IL13 and IL6). Excessive periostin expression contributed to cardiomyocyte senescent, which could be alleviated through blocking the Ang-II-TGF β1-MAPK/ERK pathway. Thus, periostin might play an important role in a vicious circle (aging-fibrosis-inflammation-aging) of heart through promoting myocardial fibrosis and cardiomyocyte senescent simultaneously. It is a potential aging marker that could be directly measured in serum.

Inhibition of periostin expression protects against the development of renal inflammation and fibrosis

Increased renal expression of periostin, a protein normally involved in embryonic and dental development, correlates with the decline of renal function in experimental models and patient biopsies. Because periostin has been reported to induce cell differentiation, we investigated whether it is also involved in the development of renal disease and whether blocking its abnormal expression improves renal function and/or structure. After unilateral ureteral obstruction in wild-type mice, we observed a progressive increase in the expression and synthesis of periostin in the obstructed kidney that associated with the progression of renal lesions. In contrast, mice lacking the periostin gene showed less injury-induced interstitial fibrosis and inflammation and were protected against structural alterations. This protection was associated with a preservation of the renal epithelial phenotype. In vitro, administration of TGF-β to renal epithelial cells increased the expression of periostin several-fold, leading to subsequent loss of the epithelial phenotype. Furthermore, treatment of these cells with periostin increased the expression of collagen I and stimulated the phosphorylation of FAK, p38, and ERK 42/44. In vivo delivery of antisense oligonucleotides to inhibit periostin expression protected animals from L-NAME-induced renal injury. These data strongly suggest that periostin mediates renal disease in response to TGF-β and that blocking periostin may be a promising therapeutic strategy against the development of CKD.

Association of serum periostin with cardiac function and short-term prognosis in acute myocardial infarction patients

Background

Periostin was proved to play an important role in extra-cellular matrix remodeling after acute myocardial infarction (AMI). Myocardial periostin was markedly up-regulated after AMI and participated in the maladaptive process of cardiac remodeling. However, few researches focused on the circulating periostin and its significance. This study aims to investigate the association of serum periostin level with cardiac function and short-term prognosis in AMI patients.

Methodology/Principal Findings

We totally recruited 50 patients diagnosed as ST-elevation myocardial infarction. Blood samples were taken within 12 hours after the onset of AMI before emergency coronary revascularization procedures. Serum periostin was measured using enzyme-linked immunosorbent assay. All patients received echocardiography examination within one week after hospitalization. Correlations of serum periostin with echocardiography parameters, Killip class and myocardium injury biomarkers (CK-MB/troponin T) were investigated. AMI patients were divided into two groups by serum periostin level (higher/lower periostin group) and followed up for six months. Primary endpoints included cardiovascular mortality, nonfatal stroke/transient ischemic attack, chest pain occurrence and re-hospitalization. Secondary endpoint referred to composite cardiovascular events including all the primary endpoints.

Result

Serum periostin was in negative association with left ventricular ejection fraction (LVEF) (r = −0.472, *p<0.01) and left atrium diameter (LAD) (r = −0.328, *p<0.05). Positive correlation was found between serum periostin level and Killip class (r = 0.395, *p<0.01). There was no association between serum periostin and CK-MB or troponin T (p>0.05). After six months follow up, patients in higher periostin group showed increased composite cardiovascular events (*p<0.05). Patients showed no significant difference in primary endpoints between the two groups.

Conclusions/Significance

Serum periostin was in negative correlation with LVEF and LAD, in positive association with Killip class and higher serum periostin level may be predictive for worse short-term disease prognosis indicated as more composite cardiovascular events six months post AMI.

Induction of autophagy contributes to the myocardial protection of valsartan against ischemia‑reperfusion injury

The mechanisms underlying the myocardial protection of valsartan against ischemia/reperfusion (I/R) injury are complicated and remain unclear. The aim of this study was to investigate whether autophagy machinery was involved in the protection against I/R injury that is induced by valsartan. In vivo rat hearts were subjected to ischemia by 30 min ligation of the left anterior descending coronary artery, followed by a 120 min reperfusion. 3‑methyladenine (3‑MA), a specific inhibitor on autophagic sequestration, was used to inhibit autophagy. The hemodynamics, infarct size of the ventricle and LC3B protein were measured. Western blot analysis was performed to investigate the mechanism by which autophagy was induced by valsartan. Valsartan preconditioning resulted in a significant decrease in infarct size and induced autophagy in the rat heart subjected to I/R injury. The hemodynamics assay showed that the valsartan‑induced cardiac functional recovery was attenuated by 3‑MA. By contrast, 3‑MA decreased the improvement induced by valsartan on the histology and infarction of the rat heart subjected to I/R injury. Valsartan preconditioning induced autophagy via the AKT/mTOR/S6K pathway, independent of Beclin1. In conclusion, valsartan preconditioning induced autophagy via the AKT/mTOR/S6K pathway, which contributed to the myocardial protection against I/R injury.

Snail1 is involved in de novo cardiac fibrosis after myocardial infarction in mice

Epithelial-mesenchymal transition (EMT) is an important mechanism of cardiac fibrosis after myocardial infarction (MI). However, it remains unclear whether Snail1, an important regulator of EMT, is involved in cardiac fibrosis. In this study, we explored the expression patterns of Snail1 and a cardiac fibrosis marker-periostin-after MI in mice and then investigated the co-expression between Snail1 and periostin after MI in mice. Our results showed that the mRNA and protein levels of Snail1 and periostin were significantly increased in the infarct area. The Snail1 expression pattern appeared to be parabolic within 14 days after MI. In addition, after MI, all Snail1-positive cells were able to express periostin. These results indicate that Snail1 is mainly activated in the infarct area and is involved in de novo cardiac fibrosis after MI in mice. Thus, it is a potential molecular target in the development of drug interventions for ventricular remodeling after MI.

Hepatocyte Growth Factor Inhibits Lipopolysaccharide-Induced Oxidative Stress via Epithelial Growth Factor Receptor Degradation

Objective—

Lipopolysaccharide (LPS) triggers sepsis and systemic inflammatory response syndrome, which results in multiple organ failure. Our recent reports demonstrated that hepatocyte growth factor (HGF) attenuated angiotensin II–induced oxidative stress via epithelial growth factor receptor (EGFR) degradation in vascular smooth muscle cells. Here, we examined whether HGF can protect against systemic inflammatory response syndrome induced by LPS and investigated the mechanism.

Methods and Results—

HGF inhibited the increase in the expression of vascular cell adhesion molecule-1 and EGFR by LPS in vitro. HGF inhibited colocalization of EGFR and Src homology domain 2–containing inositol 5′-phosphatase 2. Furthermore, HGF inhibited reactive oxygen species production. We also injected LPS into HGF transgenic mice with increased HGF serum concentration and their littermates. HGF transgenic mice reduced LPS-induced vascular cell adhesion molecule-1 and reactive oxygen species compared with control, accompanied by significant EGFR degradation. Furthermore, HGF transgenic mice significantly improved survival in the LPS injection model.

Conclusion—

The present study revealed inhibition of LPS-induced vascular cell adhesion molecule-1 expression by HGF via the degradation of EGFR. We demonstrated that HGF regulated Src homology domain 2–containing inositol 5′-phosphatase 2 recruitment to EGFR and inhibited LPS-induced inflammation via EGFR degradation. This effect of HGF may be useful for the treatment of inflammatory disease.

Deletion of periostin reduces muscular dystrophy and fibrosis in mice by modulating the transforming growth factor-β pathway

The muscular dystrophies are broadly classified as muscle wasting diseases with myofiber dropout due to cellular necrosis, inflammation, alterations in extracellular matrix composition, and fatty cell replacement. These events transpire and progress despite ongoing myofiber regeneration from endogenous satellite cells. The degeneration/regeneration response to muscle injury/disease is modulated by the proinflammatory cytokine transforming growth factor-β (TGF-β), which can also profoundly influence extracellular matrix composition through increased secretion of profibrotic proteins, such as the matricellular protein periostin. Here we show that up-regulation and secretion of periostin is pathological and enhances disease in the δ-sarcoglycan null (Sgcd(-/-)) mouse model of muscular dystrophy (MD). Indeed, MD mice lacking the Postn gene showed dramatic improvement in skeletal muscle structure and function. Mechanistically, Postn gene deletion altered TGF-β signaling so that it now enhanced tissue regeneration with reduced levels of fibrosis. Systemic antagonism of TGF-β with a neutralizing monoclonal antibody mitigated the beneficial effects of Postn deletion in vivo. These data suggest that periostin functions as a disease determinant in MD by promoting/allowing the pathological effects of TGF-β, suggesting that inhibition of periostin could represent a unique treatment approach.

Identification of periostin as a critical marker of progression/reversal of hypertensive nephropathy

Progression of chronic kidney disease (CKD) is a major health issue due to persistent accumulation of extracellular matrix in the injured kidney. However, our current understanding of fibrosis is limited, therapeutic options are lacking, and progressive degradation of renal function prevails in CKD patients. Uncovering novel therapeutic targets is therefore necessary.We have previously demonstrated reversal of renal fibrosis with losartan in experimental hypertensive nephropathy. Reversal was achieved provided that the drug was administered before late stages of nephropathy, thereby determining a non-return point of CKD progression. In the present study, to identify factors critically involved in the progression of renal fibrosis, we introduced losartan at the non-return point in L-NAME treated Sprague Dawley rats. Our results showed either reversal or progression of renal disease with losartan, defining 2 groups according to the opposite evolution of renal function. We took advantage of these experimental conditions to perform a transcriptomic screening to identify novel factors potentially implicated in the mechanisms of CKD progression. A secondary analysis of selected markers was thereafter performed. Among the targets identified, periostin, an extracellular matrix protein, presented a significant 3.3-fold higher mRNA expression in progression compared to reversal group. Furthermore, independent of blood pressure, periostin was strongly correlated with plasma creatinine, proteinuria and renal blood flow, hallmarks of hypertensive renal disease severity. Periostin staining was predominant in the injured regions, both in experimental hypertensive and human nephropathy.These results identify periostin as a previously unrecognized marker associated with disease progression and regression in hypertensive nephropathy and suggest measuring periostin may be a sensitive tool to evaluate severity, progression and response to therapy in human kidney disease associated to hypertension.

Periostin modulates myofibroblast differentiation during full-thickness cutaneous wound repair

The matricellular protein periostin is expressed in the skin. Although periostin has been hypothesized to contribute to dermal homeostasis and repair, this has not been directly tested. To assess the contribution of periostin to dermal healing, 6 mm full-thickness excisional wounds were created in the skin of periostin-knockout and wild-type, sex-matched control mice. In wild-type mice, periostin was potently induced 5-7 days after wounding. In the absence of periostin, day 7 wounds showed a significant reduction in myofibroblasts, as visualized by expression of α-smooth muscle actin (α-SMA) within the granulation tissue. Delivery of recombinant human periostin by electrospun collagen scaffolds restored α-SMA expression. Isolated wild-type and knockout dermal fibroblasts did not differ in in vitro assays of adhesion or migration; however, in 3D culture, periostin-knockout fibroblasts showed a significantly reduced ability to contract a collagen matrix, and adopted a dendritic phenotype. Recombinant periostin restored the defects in cell morphology and matrix contraction displayed by periostin-deficient fibroblasts in a manner that was sensitive to a neutralizing anti-β1-integrin and to the FAK and Src inhibitor PP2. We propose that periostin promotes wound contraction by facilitating myofibroblast differentiation and contraction.

Role of serotonin in angiogenesis: induction of angiogenesis by sarpogrelate via endothelial 5-HT1B/Akt/eNOS pathway in diabetic mice

Serotonin (5-hydroxytryptamine, 5-HT) plays a crucial role in peripheral artery disease (PAD) and diabetes mellitus (DM). In these conditions, the balance between the 5-HT2A receptor in smooth muscle cells and the 5-HT1B receptor in endothelial cells (ECs) regulates vascular tonus. In the present study, we focused on the role of 5-HT in endothelial dysfunction using a selective 5-HT2A receptor blocker, sarpogrelate. In human EC, 5-HT markedly stimulated eNOS expression and the phosphorylation of eNOS, Akt and ERK1/2. In addition, a dose-dependent increase in tubule-formation on Matrigel was observed after 5-HT treatment. In contrast, high glucose significantly inhibited tubule formation and eNOS expression through inactivation of Akt, while 5-HT significantly attenuated these actions of high glucose (P<0.01). These results indicate that 5-HT stimulated angiogenesis through activation of Akt in ECs. However, in clinical situations, 5-HT seems to act as the "devil". To examine the role of 5-HT in diabetic PAD, a hindlimb ischemia model was created in diabetic mice. The blood flow ratio of the ischemic to non-ischemic limb was significantly lower in DM mice than in normal mice, while sarpogrelate significantly attenuated the decrease in the blood flow ratio compared to control (P<0.01). Consistently, the decrease in eNOS expression and Akt activity in DM mice was significantly attenuated by sarpogrelate. Overall, the present study demonstrated that selective inhibition of 5-HT2A by sarpogrelate significantly restored ischemic limb blood perfusion in a severe diabetic mouse model through stimulation of the eNOS/Akt pathway via the endothelial 5-HT1B receptor. Enhancement of vasodilation and angiogenesis by sarpogrelate might provide a unique treatment for PAD and DM patients.

Associations among periostin gene polymorphisms, clinical parameters and heart failure: a case-control study in 1104 Chinese individuals

AIMS

To determine the associations among periostin gene polymorphisms, clinical parameters and heart failure in a Chinese population.

METHODS

In total, 464 patients with heart failure and 640 control individuals were included in this study. rs3829365 and rs1028728 were genotyped through PCR and restriction fragment length polymorphism. Multivariate logistic regression was employed to analyze the independent strength of association among clinical parameters, genotypes and heart failure.

RESULTS

rs3829365 was associated with heart failure (P = 0.043), whereas rs1028728 was not (P = 0.188). After adjusting for age, sex, hypertension, diabetes mellitus, smoking and hypertriglyceridemia in multivariate logistic regression, we found that CG or GG of rs3829365 [P = 0.015, odds ratio (OR) = 1.88] was an independent risk factor for heart failure and that CG or GG of rs3829365 (P = 0.039, OR = 0.94) and AT or TT of rs1028728 (P = 0.011, OR = 0.68) were significantly protective factors for heart failure in patients who smoked and in patients with hypertriglyceridemia, respectively. Moreover, heart failure in patients with CG or GG genotype of rs3829365 tended to be more severe than in those with CC genotype.

CONCLUSION

These findings suggest that rs3829365 of the periostin gene may be helpful to determine the susceptibility to, and severity of, heart failure. The interactions between rs3829365 and smoking and between rs1028728 and hypertriglyceridemia warrant further investigations for underlying mechanisms.

Cellular Interplay between Cardiomyocytes and Nonmyocytes in Cardiac Remodeling

Cardiac hypertrophy entails complex structural remodeling involving rearrangement of muscle fibers, interstitial fibrosis, accumulation of extracellular matrix, and angiogenesis. Many of the processes underlying cardiac remodeling have features in common with chronic inflammatory processes. During these processes, nonmyocytes, such as endothelial cells, fibroblasts, and immune cells, residing in or infiltrating into the myocardial interstitium play active roles. This paper mainly addresses the functional roles of nonmyocytes during cardiac remodeling. In particular, we focus on the communication between cardiomyocytes and nonmyocytes through direct cell-cell interactions and autocrine/paracrine-mediated pathways.

Angiotensin II increases periostin expression via Ras/p38 MAPK/CREB and ERK1/2/TGF-β1 pathways in cardiac fibroblasts

AIMS

Angiotensin II (AngII) is involved in extracellular matrix (ECM) accumulation contributing to heart failure. Periostin, a 90 kDa ECM protein, is a key regulator of cardiac fibrosis, and its expression is significantly higher in failing hearts. We determined the modulatory effect of AngII on periostin level and explored the possible signal transduction mechanism.

METHODS AND RESULTS

AngII (400 ng/kg/min) or normal saline was infused subcutaneously for 28 days into rats; AngII antagonism was with losartan (10 mg/kg/day orally). AngII infusion induced cardiac fibrosis and increased periostin expression, which was attenuated by losartan. In cultured adult rat cardiac fibroblasts, AngII promoted the mRNA and protein expression of periostin. AngII provoked activation of cAMP response element-binding protein (CREB), and CREB small interfering RNA (siRNA) suppressed AngII-induced periostin expression. Inhibition of p38 mitogen-activated protein kinase (p38 MAPK) with SB202190 attenuated AngII-induced CREB activation and periostin expression. Transfection with Ras guanyl-releasing protein 1 siRNA or RasN17 dominant-negative plasmid prevented AngII-induced p38 MAPK phosphorylation and periostin expression. Transforming growth factor (TGF)-β1 antibody decreased the stimulatory effect of AngII on periostin expression. The extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitor PD98059 attenuated AngII-induced TGF-β1 expression, Smad2/3 nuclear accumulation, and periostin expression.

CONCLUSION

The activation of the Ras/p38 MAPK/CREB pathway is required for AngII-induced periostin expression. ERK1/2 also participates in AngII-induced periostin expression by regulating TGF-β1/Smad signalling.

Hepatocyte growth factor attenuates transforming growth factor-β-angiotensin II crosstalk through inhibition of the PTEN/Akt pathway

Both angiotensin II (Ang II) and transforming growth factor (TGF)-β1 are thought to be involved in the progression of chronic kidney disease. In contrast, hepatocyte growth factor (HGF) counteracts the actions of Ang II and TGF-β1. Therefore, in this study, we investigated the molecular mechanisms of how HGF antagonizes the Ang II-TGF-β axis in renal cells. In cultured human mesangial cells, TGF-β1 increased angiotensin type 1 receptor (AT(1)R) mRNA, mainly dependent on the Akt/phosphatidylinositol 3-kinase signaling pathway. Furthermore, TGF-β1 decreased the expression and phosphatase activity of phosphatase and tensin homolog, deleted on chromosome 10 (PTEN), a negative regulator of the phosphatidylinositol 3-kinase/Akt pathway. These data revealed positive feedback of the Ang II-TGF-β pathway, because Ang II increased TGF-β expression. In contrast, HGF significantly attenuated the increase in AT(1)R gene expression, and inhibited the decrease in PTEN induced by TGF-β1. Of importance, a PTEN-specific inhibitor significantly attenuated the reduction in TGF-β1-induced AT(1)R expression by HGF. These data suggest that HGF attenuated TGF-β1-induced AT(1)R expression through the PTEN/Akt pathway. To investigate this hypothesis, we performed in vivo experiments in mice with increased circulating levels of HGF produced by transgenically expressing HGF under control of a cardiac-specific transgene (HGF-Tg). In HGF-Tg mice, renal injury and fibrosis were significantly decreased, associated with reduction in AT(1)R expression and increase in PTEN after Ang II infusion, as compared with control mice. Moreover, these renal protective effects were abrogated by a neutralizing antibody against HGF. Thus, the present study demonstrated that HGF counteracts the vicious cycle of Ang II-TGF-β1-AT(1)R, mediating the inhibition of PTEN.

Hepatocyte growth factor attenuates renal fibrosis through TGF-β1 suppression by apoptosis of myofibroblasts

OBJECTIVE

The progression of chronic kidney disease (CKD) is characterized by the persistent accumulation of extracellular matrix. Especially, α-SMA-positive myofibroblasts producing large amounts of TGF-β1 are considered to play a key role in interstitial fibrosis. Although hepatocyte growth factor (HGF) improved renal fibrosis in various models, the molecular mechanisms involved are not yet fully understood.

METHODS AND RESULTS

In this study, the molecular mechanisms of the inhibition of fibrosis by HGF was examined using HGF transgenic mice (HGF-Tg) with angiotensin II (Ang II) infusion in 4 weeks models. HGF-Tg mice showed significantly decreased Ang II-induced renal fibrosis and lesser numbers of interstitial myofibroblasts, whereas the antifibrotic effect of HGF was abrogated using HGF-neutralizing antibody. The antifibrotic action in HGF-Tg mice was concordant with a decrease in TGF- β1, collagen type I and IV mRNA expression and an increase in MMP-2 and MMP-9 expression. Furthermore, HGF-Tg mice treated with Ang II showed apoptosis of myofibroblasts. To further investigate the antifibrotic effect of HGF, cultured human mesangial cells were used. HGF induced apoptosis of myofibroblast. Inhibition of the FAK-ERK-MMP signaling cascade by specific inhibitor or siRNA significantly decreased HGF-induced myofibroblast apoptosis.

CONCLUSION

The present study demonstrates that the increase in metalloproteinases through FAK-ERK signaling by HGF promotes myofibroblast apoptosis. Activation of metalloproteinases by HGF in the fibrotic kidney might be considered to attenuate the progression of CKD.

Development of a new ELISA for serum periostin: evaluation of growth-related changes and bisphosphonate treatment in mice

Periostin is a gamma-carboxyglutamic acid protein preferentially expressed in periosteum and bone mesenchymal stem cells. Lack of a precise assay for measuring circulating levels impairs the investigation of its biological significance. We developed a new ELISA and studied changes of periostin levels both locally at the bone site and systemically in circulating blood during growth and after bisphosphonate-induced inhibition of bone remodeling in the mouse. The ELISA we developed is based on an affinity-purified polyclonal antibody that was raised against the C-terminal sequence of mouse periostin. Reproducibility, repeatability, precision, and accuracy tests met standards of acceptance. Serum periostin and levels of the bone turnover markers osteocalcin, PINP, CTX-I, and TRAP5b were measured in (1) 4-, 6-, 8-, 10-, and 12-week-old wild-type female Balb/c mice and (2) adult ovariectomized female Balb/c mice treated with zoledronic acid or vehicle. Serum periostin decreased during growth and stabilized from 8 weeks and older, its levels correlating with bone turnover markers. Immunohistochemistry in bones from different growth stages showed that periostin localized specifically at the sites of endochondral and intramembranous ossification, especially at the periosteal envelopes. Zoledronic acid induced a marked decrease in bone remodeling markers but did not alter serum periostin levels or periostin immunostaining pattern. The novel ELISA is highly specific and allows accurate and precise measurements of serum periostin levels in mice.

Origin of cardiac fibroblasts and the role of periostin

Cardiac fibroblasts are the most populous nonmyocyte cell type within the mature heart and are required for extracellular matrix synthesis and deposition, generation of the cardiac skeleton, and to electrically insulate the atria from the ventricles. Significantly, cardiac fibroblasts have also been shown to play an important role in cardiomyocyte growth and expansion of the ventricular chambers during heart development. Although there are currently no cardiac fibroblast-restricted molecular markers, it is generally envisaged that the majority of the cardiac fibroblasts are derived from the proepicardium via epithelial-to-mesenchymal transformation. However, still relatively little is known about when and where the cardiac fibroblasts cells are generated, the lineage of each cell, and how cardiac fibroblasts move to reside in their final position throughout all four cardiac chambers. In this review, we summarize the present understanding regarding the function of Periostin, a useful marker of the noncardiomyocyte lineages, and its role during cardiac morphogenesis. Characterization of the cardiac fibroblast lineage and identification of the signals that maintain, expand and regulate their differentiation will be required to improve our understanding of cardiac function in both normal and pathophysiological states.

The many facets of the matricelluar protein periostin during cardiac development, remodeling, and pathophysiology

Periostin is a member of a growing family of matricellular proteins, defined by their ability to interact with components of the extracellular milieu, and with receptors at the cell surface. Through these interactions, periostin has been shown to play a crucial role as a profibrogenic molecule during tissue morphogenesis. Tissues destined to become fibrous structures are dependent on cooperative interactions between periostin and its binding partners, whereas in its absence, these structures either totally or partially fail to become mature fibrous entities. Within the heart, fibrogenic differentiation is required for normal tissue maturation, remodeling and function, as well as in response to a pathological myocardial insult. In this review, aspects related to the function of periostin during cardiac morphogenesis, remodeling and pathology are summarized.

Negative action of hepatocyte growth factor/c-Met system on angiotensin II signaling via ligand-dependent epithelial growth factor receptor degradation mechanism in vascular smooth muscle cells

RATIONALE

Neointimal hyperplasia contributes to atherosclerosis and restenosis after percutaneous coronary intervention. Vascular injury in each of these conditions results in the release of mitogenic growth factors and hormones that contribute to pathological vascular smooth muscle cell growth and inflammation. Hepatocyte growth factor (HGF) is known as an antiinflammatory growth factor, although it is downregulated in injured tissue. However, the precise mechanism how HGF reduces inflammation is unclear.

OBJECTIVE

To elucidate the mechanism how HGF and its receptor c-Met reduces angiotensin II (Ang II)-induced inflammation.

METHODS AND RESULTS

HGF reduced Ang II-induced vascular smooth muscle cell growth and inflammation by controlling translocation of SHIP2 (Src homology domain 2-containing inositol 5'-phosphatase 2), which led to Ang II-dependent degradation of epithelial growth factor receptor. Moreover, the present study also revealed a preventive effect of HGF on atherosclerotic change in an Ang II infusion and cuff HGF transgenic mouse model.

CONCLUSIONS

These data suggest that the HGF/c-Met system might regulate extrinsic factor signaling that maintains the homeostasis of organs.

Sartan-AT1 receptor interactions: in vitro evidence for insurmountable antagonism and inverse agonism

Sartans are non-peptide AT(1) receptor antagonists used to treat hypertension and related pathologies. Their effects on the G protein-dependent responses of angiotensin II (Ang II) were the same in vascular tissues and in isolated cell systems. All are competitive but, when pre-incubated, they act surmountably (only rightward shift of the Ang II concentration-response curve) or insurmountably (also decreasing the maximal response). Insurmountable behaviour reflects the formation of tight sartan-receptor complexes; it is often partial due to the co-existence of tight and loose complexes. Their ratio positively correlates with the dissociation half-life of the tight complexes and depends on the sartan: i.e. candesartan>olmesartan>telmisartan approximately equal EXP3174>valsartan>irbesartan>>losartan. When AT(1) receptors display sufficient basal activity (in case of receptor over-expression, mutation and, especially, tissue stretching) sartans may also act as inverse agonists. This rather affects long-term, G protein-independent hypertrophic responses leading to cardiovascular remodelling.

Hepatocyte Growth Factor, but not Vascular Endothelial Growth Factor, Attenuates Angiotensin II–Induced Endothelial Progenitor Cell Senescence

Although both hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF) are potent angiogenic growth factors in animal models of ischemia, their characteristics are not the same in animal experiments and clinical trials. To elucidate the discrepancy between HGF and VEGF, we compared the effects of HGF and VEGF on endothelial progenitor cells under angiotensin II stimulation, which is a well-known risk factor for atherosclerosis. Here, we demonstrated that HGF, but not VEGF, attenuated angiotensin II–induced senescence of endothelial progenitor cells through a reduction of oxidative stress by inhibition of the phosphatidylinositol-3,4,5-triphosphate/rac1 pathway. Potent induction of neovascularization of endothelial progenitor cells by HGF, but not VEGF, under angiotensin II was also confirmed by in vivo experiments using several models, including HGF transgenic mice.

Functional role of periostin in development and wound repair: implications for connective tissue disease

Integrity of the extracellular matrix (ECM) is essential for maintaining the normal structure and function of connective tissues. ECM is secreted locally by cells and organized into a complex meshwork providing physical support to cells, tissues, and organs. Initially thought to act only as a scaffold, the ECM is now known to provide a myriad of signals to cells regulating all aspects of their phenotype from morphology to differentiation. Matricellular proteins are a class of ECM related molecules defined through their ability to modulate cell-matrix interactions. Matricellular proteins are expressed at high levels during development, but typically only appear in postnatal tissue in wound repair or disease, where their levels increase substantially. Members of the CCN family, tenascin-C, osteopontin, secreted protein acidic rich in cysteine (SPARC), bone sialoprotein, thrombospondins, and galectins have all been classed as matricellular proteins. Periostin, a 90 kDa secreted homophilic cell adhesion protein, was recently added to matricellular class of proteins based on its expression pattern and function during development as well as in wound repair. Periostin is expressed in connective tissues including the periodontal ligament, tendons, skin and bone, and is also prominent in neoplastic tissues, cardiovascular disease, as well as in connective tissue wound repair. This review will focus on the functional role of periostin in tissue physiology. Fundamentally, it appears that periostin influences cell behaviour as well as collagen fibrillogenesis, and therefore exerts control over the structural and functional properties of connective tissues in both health and disease. Periostin is a novel matricellular protein with close homology to Drosophila fasciclin 1. In this review, the functional role of periostin is discussed in the context of connective tissue physiology, in development, disease, and wound repair.

Periostin facilitates eosinophil tissue infiltration in allergic lung and esophageal responses

Periostin is an extracellular matrix protein that has been primarily studied in the context of the heart, where it has been shown to promote cardiac repair and remodeling. In this study, we focused on the role of periostin in an allergic eosinophilic inflammatory disease (eosinophilic esophagitis (EE)) known to involve extensive tissue remodeling. Periostin was indeed markedly overexpressed (35-fold) in the esophagus of EE patients, particularly in the papillae, compared with control individuals. Periostin expression was downstream from transforming growth factor-beta and interleukin-13, as these cytokines were elevated in EE esophageal samples and markedly induced periostin production by primary esophageal fibroblasts (107- and 295-fold, respectively, at 10 ng ml(-1)). A functional role for periostin in eliciting esophageal eosinophilia was demonstrated, as periostin-null mice had a specific defect in allergen-induced eosinophil recruitment to the lungs and esophagus (66 and 72% decrease, respectively). Mechanistic analyses revealed that periostin increased (5.8-fold) eosinophil adhesion to fibronectin. As such, these findings extend the involvement of periostin to esophagitis and uncover a novel role for periostin in directly regulating leukocyte (eosinophil) accumulation in T helper type 2-associated mucosal inflammation in both mice and humans.

Molecular and physiological characterization of RV remodeling in a murine model of pulmonary stenosis

Right ventricular (RV) dysfunction is a common long-term complication in patients after the repair of congenital heart disease. Previous investigators have examined the cellular and molecular mechanisms of left ventricular (LV) remodeling, but little is known about the stressed RV. Our purpose was to provide a detailed physiological characterization of a model of RV hypertrophy and failure, including RV-LV interaction, and to compare gene alterations between afterloaded RV versus LV. Pulmonary artery constriction was performed in 86 mice. Mice with mild and moderate pulmonary stenosis (PS) developed stable hypertrophy without decompensation. Mice with severe PS developed edema, decreased RV function, and high mortality. Tissue Doppler imaging demonstrated septal dyssynchrony and deleterious RV-LV interaction in the severe PS group. Microarray analysis showed 196 genes with increased expression and 1,114 with decreased expression. Several transcripts were differentially increased in the afterloaded RV but not in the afterloaded LV, including clusterin, neuroblastoma suppression of tumorigenicity 1, Dkk3, Sfrp2, formin binding protein, annexin A7, and lysyl oxidase. We have characterized a murine model of RV hypertrophy and failure, providing a platform for studying the physiological and molecular events of RV remodeling. Although the molecular responses of the RV and LV to afterload stress are mostly concordant, there are several key differences, which may represent targets for RV failure-specific therapy.

Epicardium-derived cells in development of annulus fibrosis and persistence of accessory pathways

BACKGROUND

The developmental mechanisms underlying the persistence of myocardial accessory atrioventricular pathways (APs) that bypass the annulus fibrosis are mainly unknown. In the present study, we investigated the role of epicardium-derived cells (EPDCs) in annulus fibrosis formation and the occurrence of APs.

METHODS AND RESULTS

EPDC migration was mechanically inhibited by in ovo microsurgery in quail embryos. In ovo ECGs were recorded in wild-type (n=12) and EPDC-inhibited (n=12) hearts at Hamburger-Hamilton (HH) stages 38 to 42. Subsequently, in these EPDC-inhibited hearts (n=12) and in additional wild-type hearts (n=45; HH 38-42), ex ovo extracellular electrograms were recorded. Electrophysiological data were correlated with differentiation markers for cardiomyocytes (MLC2a) and fibroblasts (periostin). In ovo ECGs showed significantly shorter PR intervals in EPDC-inhibited hearts (45+/-10 ms) than in wild-type hearts (55+/-8 ms, 95% CI 50 to 60 ms, P=0.030), whereas the QRS durations were significantly longer in EPDC-inhibited hearts (29+/-14 versus 19+/-2 ms, 95% CI 18 to 21 ms, P=0.011). Furthermore, ex ovo extracellular electrograms (HH 38-42) displayed base-first ventricular activation in 44% (20/45) of wild-type hearts, whereas in all EPDC-inhibited hearts (100%, 12/12), the ventricular base was activated first (P<0.001). Small periostin- and MLC2a-positive APs were found mainly in the posteroseptal region of both wild-type and EPDC-inhibited hearts. Interestingly, in all (n=10) EPDC-inhibited hearts, additional large periostin-negative and MLC2a-positive APs were found in the right and left lateral free wall coursing through marked isolation defects in the annulus fibrosis until the last stages of embryonic development.

CONCLUSIONS

EPDCs play an important role in annulus fibrosis formation. EPDC outgrowth inhibition may result in marked defects in the fibrous annulus with persistence of large APs, which results in ventricular preexcitation on ECG. These APs may provide a substrate for postnatally persistent reentrant arrhythmias.

Periostin is required for maturation and extracellular matrix stabilization of noncardiomyocyte lineages of the heart

The secreted periostin protein, which marks mesenchymal cells in endocardial cushions following epithelial-mesenchymal transformation and in mature valves following remodeling, is a putative valvulogenesis target molecule. Indeed, periostin is expressed throughout cardiovascular morphogenesis and in all 4 adult mice valves (annulus and leaflets). Additionally, periostin is expressed throughout the fibrous cardiac skeleton and endocardial cushions in the developing heart but is absent from both normal and/or pathological mouse cardiomyocytes. Periostin (peri(lacZ)) knockout mice exhibit viable valve disease, with neonatal lethality in a minority and latent disease with leaflet abnormalities in the viable majority. Surviving peri(lacZ)-null leaflets are truncated, contain ectopic cardiomyocytes and smooth muscle, misexpress the cartilage proteoglycan aggrecan, demonstrate disorganized matrix stratification, and exhibit reduced transforming growth factor-beta signaling. Neonatal peri(lacZ) nulls that die (14%) display additional defects, including leaflet discontinuities, delamination defects, and deposition of acellular extracellular matrix. Assessment of collagen production, 3D lattice formation ability, and transforming growth factor-beta responsiveness indicate periostin-deficient fibroblasts are unable to support normal valvular remodeling and establishment of a mature cardiac skeleton. Furthermore, pediatric stenotic bicuspid aortic valves that have lost normal extracellular matrix trilaminar stratification have greatly reduced periostin. This suggests that loss of periostin results in inappropriate differentiation of mesenchymal cushion cells and valvular abnormalities via a transforming growth factor-beta-dependent pathway during establishment of the mature heart. Thus, peri(lacZ) knockouts provide a new model of viable latent valve disease.