Follistatin-like 1 protects against hypoxia-induced pulmonary hypertension in mice

Circulating Myokines as Novel Biomarkers for Cardiovascular Diseases

Myokines are a group of cytokines or polypeptides released from skeletal muscle during exercise. Growing evidence suggests that myokines are associated with the development of cardiovascular disease (CVD). Moreover, several myokines in peripheral blood exhibit dynamic changes in different CVD stages. This review summarizes the potential roles of myokines such as myostatin, irisin, brain-derived neurotrophic factor, mitsugumin 53, meteorin-like, and apelin in various CVD, including myocardial infarction, heart failure, atherosclerosis, hypertension, and diabetes. The association of these myokines with biomarkers currently being used in clinical practice is also discussed. Furthermore, the review considers the emerging role of myokines in CVD and addresses the challenges remaining in translating these discoveries into novel clinical biomarkers for CVD.

LncRNA HCG18 promotes inflammation and apoptosis in intervertebral disc degeneration via the miR-495-3p/FSTL1 axis

Intervertebral disc degeneration (IDD) causes pain in the back and neck. This study investigated the role of long non-coding RNA HLA complex group 18 (HCG18) in a cell model of IDD. An IDD model was established by stimulating nucleus pulposus (NP) cells with interleukin (IL)-1β. MTT assay was performed to evaluate NP cell viability. The apoptosis was detected by flow cytometry. The expressions of HCG18, microRNA (miR)-495-3p, and follistatin-like protein-1 (FSTL1) were measured by RT-qPCR. The interactions of miR-495-3p with HCG18 and FSTL1 were analyzed by luciferase reporter assay. IL-1β stimulation upregulated HCG18 and FSTL1, but downregulated miR-495-3p in NP cells. Silencing of HCG18 or FSTL1, as well as miR-495-3p overexpression in NP cells alleviated IL-1β-induced apoptosis and inflammation of NP cells. Both HCG18 and FSTL1 had binding sites for miR-495-3p. Overexpression of FSTL1 abolished the effects of HCG18 silencing on IL-1β-induced apoptosis and inflammation. The HCG18/miR-495-3p/FSTL1 axis is essential for IDD development. Therapeutic strategies targeting this axis may be used for IDD treatment.

The Role of Bone Morphogenetic Protein 4 in Lung Diseases

Bone morphogenetic protein 4 (BMP4) is a multifunctional secretory protein that belongs to the transforming growth factor β superfamily. BMPs transduce their signaling to the cytoplasm by binding to membrane receptors of the serine/threonine kinase family, including BMP type I and type II receptors. BMP4 participates in various biological processes, such as embryonic development, epithelial-mesenchymal transition, and maintenance of tissue homeostasis. The interaction between BMP4 and the corresponding endogenous antagonists plays a key role in the precise regulation of BMP4 signaling. In this paper, we review the pathogenesis of BMP4-related lung diseases and the foundation on which BMP4 endogenous antagonists have been developed as potential targets.

FSTL1-knockdown improves neural oscillation via decreasing neuronal-inflammation regulating apoptosis in Aβ1-42 induced AD model mice

Follistatin like protein 1 (FSTL1) is a famous growth regulatory protein. FSTL1 has been noticed in many diseases, including heart and lung ischemia, cerebral ischemia, glioma, schizophrenia, and Autism. The role of FSTL1 has been declared in the genetics and development of the central nervous system. Therefore, we designed this study to investigate the function and the role of FSTL1 in Alzheimer's disease. Firstly, we noticed upregulated expression level of FSTL1 among four to six-month-old 5XFAD AD mice. Accordingly, we hypothesized that FSTL1-Knockdown improved AD model mice's cognitive function and recover from Alzheimer's disease. Thus, AD model mice were made by single intracerebroventricular injections of Aβ_1-42 peptides in FSTL1^+/- and CON mice. Next, our results concluded that FSTL1-knockdown effectively improved cognitive functions. FSTL1-knockdown enhanced the pattern of neural oscillations, and synaptic plasticity in Aβ_1-42 treated FSTL1-Knockdown mice compared to Aβ_1-42 induced AD model mice. Next, FSTL1-Knockdown inhibited the activation of microglia and binding of TLR-4 with microglia. Further, inactivated microglia stopped the formation of MyD88. Thus, our data revealed that FSTL1-Knockdown is slowing down the caspase/BAX/Bcl-2/TLR-4 regulating apoptosis pathway, and the expression of inflammatory cytokines in the hippocampus of Aβ_1-42 inserted FSTL1-Knockdown mice. Overall, all these data illuminate the clinical significance role of down-regulated FSTL1. FSTL1-Knockdown reduced the amyloid-beta by affecting microglia, neural-inflammation and apoptosis in AD-like model mice. Finally, down regulation of FSTL1 improved synaptic plasticity, neural oscillations, and cognitive behaviours in the Aβ_1-42 induced AD model mice.

An integrated proteomic and transcriptomic signature of the failing right ventricle in monocrotaline induced pulmonary arterial hypertension in male rats

Aim: Pulmonary arterial hypertension (PAH) is an obstructive pulmonary vasculopathy that results in death from right ventricular failure (RVF). There is limited understanding of the molecular mechanisms of RVF in PAH. Methods: In a PAH-RVF model induced by injection of adult male rats with monocrotaline (MCT; 60 mg/kg), we performed mass spectrometry to identify proteins that change in the RV as a consequence of PAH induced RVF. Bioinformatic analysis was used to integrate our previously published RNA sequencing data from an independent cohort of PAH rats. Results: We identified 1,277 differentially regulated proteins in the RV of MCT rats compared to controls. Integration of MCT RV transcriptome and proteome data sets identified 410 targets that are concordantly regulated at the mRNA and protein levels. Functional analysis of these data revealed enriched functions, including mitochondrial metabolism, cellular respiration, and purine metabolism. We also prioritized 15 highly enriched protein:transcript pairs and confirmed their biological plausibility as contributors to RVF. We demonstrated an overlap of these differentially expressed pairs with data published by independent investigators using multiple PAH models, including the male SU5416-hypoxia model and several male rat strains. Conclusion: Multiomic integration provides a novel view of the molecular phenotype of RVF in PAH which includes dysregulation of pathways involving purine metabolism, mitochondrial function, inflammation, and fibrosis.

Follistatin-like 1 and Biomarkers of Neutrophil Activation Are Associated with Poor Short-Term Outcome after Lung Transplantation on VA-ECMO

The investigation of biomarkers associated with undesired outcome following lung transplantation (LuTX) is essential for a better understanding of the underlying pathophysiology, an earlier identification of susceptible recipients and the development of targeted therapeutic options. We therefore determined the longitudinal perioperative course of putative cytokines related to neutrophil activation (chemokine CC motif ligand 4 (CCL-4), interleukin (IL)-23 and Lipocalin 2 (LCN2)) and a cytokine that has been implicated in graft-versus-host disease (Follistatin-like 1 (FSTL1)) in 42 consecutive patients undergoing LuTX. We plotted receiver-operating curves (ROC) to assess the predictive power of the measured cytokines for short-term outcomes namely primary graft dysfunction (PGD), early complications requiring extracorporeal membrane oxygenation (ECMO), and a high postoperative sequential organ failure assessment (SOFA). All cytokines increased immediately after surgery. ROC analyses determined significant associations between CCL4 and a high SOFA score (area under the curve (AUC) 0.74 (95%CI:0.5−0.9; p < 0.05), between LCN2 and postoperative ECMO support (AUC 0.73 (95%CI:0.5−0.9; p < 0.05), and between FSTL1 and PGD (AUC 0.70 (95%CI:0.5−0.9; p < 0.05). The serum concentrations of the neutrophil-derived cytokines LCN2 and CCL4 as well as FSTL1 were all related to poor outcome after LuTX. The specific predictive power, however, still has to be assessed in larger trials. The potential role of FSTL1 as a biomarker in the development of PGD could be of great interest particularly since this protein appears to play a crucial role in allograft tolerance.

Follistatin-Like Proteins: Structure, Functions and Biomedical Importance

Main forms of cellular signal transmission are known to be autocrine and paracrine signaling. Several cells secrete messengers called autocrine or paracrine agents that can bind the corresponding receptors on the surface of the cells themselves or their microenvironment. Follistatin and follistatin-like proteins can be called one of the most important bifunctional messengers capable of displaying both autocrine and paracrine activity. Whilst they are not as diverse as protein hormones or protein kinases, there are only five types of proteins. However, unlike protein kinases, there are no minor proteins among them; each follistatin-like protein performs an important physiological function. These proteins are involved in a variety of signaling pathways and biological processes, having the ability to bind to receptors such as DIP2A, TLR4, BMP and some others. The activation or experimentally induced knockout of the protein-coding genes often leads to fatal consequences for individual cells and the whole body as follistatin-like proteins indirectly regulate the cell cycle, tissue differentiation, metabolic pathways, and participate in the transmission chains of the pro-inflammatory intracellular signal. Abnormal course of these processes can cause the development of oncology or apoptosis, programmed cell death. There is still no comprehensive understanding of the spectrum of mechanisms of action of follistatin-like proteins, so the systematization and study of their cellular functions and regulation is an important direction of modern molecular and cell biology. Therefore, this review focuses on follistatin-related proteins that affect multiple targets and have direct or indirect effects on cellular signaling pathways, as well as to characterize the directions of their practical application in the field of biomedicine.

iPSC-endothelial cell phenotypic drug screening and in silico analyses identify tyrphostin-AG1296 for pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a progressive disorder leading to occlusive vascular remodeling. Current PAH therapies improve quality of life but do not reverse structural abnormalities in the pulmonary vasculature. Here, we used high-throughput drug screening combined with in silico analyses of existing transcriptomic datasets to identify a promising lead compound to reverse PAH. Induced pluripotent stem cell-derived endothelial cells generated from six patients with PAH were exposed to 4500 compounds and assayed for improved cell survival after serum withdrawal using a chemiluminescent caspase assay. Subsequent validation of caspase activity and improved angiogenesis combined with data analyses using the Gene Expression Omnibus and Library of Integrated Network-Based Cellular Signatures databases revealed that the lead compound AG1296 was positively associated with an anti-PAH gene signature. AG1296 increased abundance of bone morphogenetic protein receptors, downstream signaling, and gene expression and suppressed PAH smooth muscle cell proliferation. AG1296 induced regression of PA neointimal lesions in lung organ culture and PA occlusive changes in the Sugen/hypoxia rat model and reduced right ventricular systolic pressure. Moreover, AG1296 improved vascular function and BMPR2 signaling and showed better correlation with the anti-PAH gene signature than other tyrosine kinase inhibitors. Specifically, AG1296 up-regulated small mothers against decapentaplegic (SMAD) 1/5 coactivators, cAMP response element-binding protein 3 (CREB3), and CREB5: CREB3 induced inhibitor of DNA binding 1 and downstream genes that improved vascular function. Thus, drug discovery for PAH can be accelerated by combining phenotypic screening with in silico analyses of publicly available datasets.

FSTL1 aggravates cigarette smoke-induced airway inflammation and airway remodeling by regulating autophagy

BACKGROUND

Cigarette smoke (CS) is a major risk factor for Chronic Obstructive Pulmonary Disease (COPD). Follistatin-like protein 1 (FSTL1), a critical factor during embryogenesis particularly in respiratory lung development, is a novel mediator related to inflammation and tissue remodeling. We tried to investigate the role of FSTL1 in CS-induced autophagy dysregulation, airway inflammation and remodeling.

METHODS

Serum and lung specimens were obtained from COPD patients and controls. Adult female wild-type (WT) mice, FSTL1^± mice and FSTL1^flox/+ mice were exposed to room air or chronic CS. Additionally, 3-methyladenine (3-MA), an inhibitor of autophagy, was applied in CS-exposed WT mice. The lung tissues and serum from patients and murine models were tested for FSTL1 and autophagy-associated protein expression by ELISA, western blotting and immunohistochemical. Autophagosome were observed using electron microscope technology. LTB4, IL-8 and TNF-α in bronchoalveolar lavage fluid of mice were examined using ELISA. Airway remodeling and lung function were also assessed.

RESULTS

Both FSTL1 and autophagy biomarkers increased in COPD patients and CS-exposed WT mice. Autophagy activation was upregulated in CS-exposed mice accompanied by airway remodeling and airway inflammation. FSTL1^± mice showed a lower level of CS-induced autophagy compared with the control mice. FSTL1^± mice can also resist CS-induced inflammatory response, airway remodeling and impaired lung function. CS-exposed WT mice with 3-MA pretreatment have a similar manifestation with CS-exposed FSTL1^± mice.

CONCLUSIONS

FSTL1 promotes CS-induced COPD by modulating autophagy, therefore targeting FSTL1 and autophagy may shed light on treating cigarette smoke-induced COPD.

Modulatory Effect of Myokines on Reactive Oxygen Species in Ischemia/Reperfusion

There is a growing body of evidence showing the importance of physical activity against acute ischemic events in various organs. Ischemia/reperfusion injury (I/R) is characterized by tissue damage as a result of restriction and subsequent restoration of blood supply to an organ. Oxidative stress due to increased reactive oxygen species formation and/or insufficient antioxidant defense is considered to play an important role in I/R. Physical activity not only decreases the general risk factors for ischemia but also confers direct anti-ischemic protection via myokine production. Myokines are skeletal muscle-derived cytokines, representing multifunctional communication channels between the contracting skeletal muscle and other organs through an endocrine manner. In this review, we discuss the most prominent members of the myokines (i.e., brain-derived neurotrophic factor (BDNF), cathepsin B, decorin, fibroblast growth factors-2 and -21, follistatin, follistatin-like, insulin-like growth factor-1; interleukin-6, interleukin-7, interleukin-15, irisin, leukemia inhibitory factor, meteorin-like, myonectin, musclin, myostatin, and osteoglycin) with a particular interest in their potential influence on reactive oxygen and nitrogen species formation or antioxidant capacity. A better understanding of the mechanism of action of myokines and particularly their participation in the regulation of oxidative stress may widen their possible therapeutic use and, thereby, may support the fight against I/R.

Unsupervised discovery of phenotype-specific multi-omics networks

MOTIVATION

Complex diseases often involve a wide spectrum of phenotypic traits. Better understanding of the biological mechanisms relevant to each trait promotes understanding of the etiology of the disease and the potential for targeted and effective treatment plans. There have been many efforts towards omics data integration and network reconstruction, but limited work has examined the incorporation of relevant (quantitative) phenotypic traits.

RESULTS

We propose a novel technique, sparse multiple canonical correlation network analysis (SmCCNet), for integrating multiple omics data types along with a quantitative phenotype of interest, and for constructing multi-omics networks that are specific to the phenotype. As a case study, we focus on miRNA-mRNA networks. Through simulations, we demonstrate that SmCCNet has better overall prediction performance compared to popular gene expression network construction and integration approaches under realistic settings. Applying SmCCNet to studies on chronic obstructive pulmonary disease (COPD) and breast cancer, we found enrichment of known relevant pathways (e.g. the Cadherin pathway for COPD and the interferon-gamma signaling pathway for breast cancer) as well as less known omics features that may be important to the diseases. Although those applications focus on miRNA-mRNA co-expression networks, SmCCNet is applicable to a variety of omics and other data types. It can also be easily generalized to incorporate multiple quantitative phenotype simultaneously. The versatility of SmCCNet suggests great potential of the approach in many areas.

AVAILABILITY AND IMPLEMENTATION

The SmCCNet algorithm is written in R, and is freely available on the web at https://cran.r-project.org/web/packages/SmCCNet/index.html.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Follistatin like protein-1 modulates macrophage polarization and aggravates dextran sodium sulfate-induced colitis

Follistatin-like protein 1 (FSTL1) is a pleiotropic cytokine involved in multiple processes including organ development, carcinogenesis, metastasis and so on. Some recent studies have suggested a possible role of FSTL1 in the inflammatory diseases. We for the first time tried to unravel its effect on the colitis, and explore the possible mechanisms. Here we found that FSTL1 was upregulated in active human and murine colitis. It facilitated proinflammatory M1 polarization of macrophages and inhibited the M2 anti-inflammatory phenotype, leading to excessive production of multiple inflammatory cytokines in vitro and in vivo. Haplodeletion of FSTL1 in mice significantly reduced the clinical and histological activity of colitis. Most importantly, macrophage depletion diminished the difference between DSS-treated WT and FSTL1^+/- mice. Altogether, our results suggested that FSTL1 may also serve as an important contributor in the colonic inflammation. The possible mechanism may be related to its modulation on macrophage polarization.

Follistatin-like 1 in Cardiovascular Disease and Inflammation

Follistatin-like 1 (FSTL1), a secreted glycoprotein, has been shown to participate in regulating developmental processes and to be involved in states of disease and injury. Spatiotemporal regulation and posttranslational modifications contribute to its specific functions and make it an intriguing candidate to study disease mechanisms and potentially develop new therapies. With cardiovascular diseases as the primary cause of death worldwide, clarification of mechanisms underlying cardiac regeneration and revascularization remains essential. Recent findings on FSTL1 in both acute coronary syndrome and heart failure emphasize its potential as a target for cardiac regenerative therapy. With this review, we aim to shed light on the role of FSTL1 specifically in cardiovascular disease and inflammation.

Follistatin-Like 1 Attenuates Ischemia/Reperfusion Injury in Cardiomyocytes via Regulation of Autophagy

Background

The cardioprotective effect of FSTL1 has been extensively studied in recent years, but its role in myocardial ischemia/reperfusion injury (IRI) is unclear. In this study, we investigated the effect of FSTL1 pretreatment on myocardial IRI as well as the possible involvement of autophagic pathways in its effects.

Methods

The effects of FSTL1 on the viability and apoptosis of rat cardiomyocytes were investigated after exposure of cardiomyocytes to hypoxia/ischemia by using the CCK-8 assay and Annexin V/PI staining. Further, western blot analysis was used to detect the effects of FSTL1 pretreatment on autophagy-associated proteins, and confocal microscopy was used to observe autophagic flux. To confirm the role of autophagy, the cells were treated with the autophagy promoter rapamycin or the autophagy inhibitor 3-methyladenine, and cell viability and apoptosis during IRI were observed. These effects were also observed after treatment with rapamycin or 3-methyladenine followed by FSTL1 administration and IRI.

Results

FSTL1 pretreatment significantly increased viability and reduced apoptosis in cardiomyocytes exposed to hypoxia/ischemia conditions. Further, FSTL1 pretreatment affected the levels of the autophagy-related proteins and enhanced autophagic flux during IRI. In addition, cell viability was enhanced and apoptosis was decreased by rapamycin treatment, while these effects were reversed by 3-MA treatment. However, when the myocardial cells were pretreated with rapamycin or 3-methyladenine, there was no significant change in their viability or apoptosis with FSTL1 treatment during IRI.

Conclusions

FSTL1 plays a protective role in myocardial IRI by regulating autophagy.

Long noncoding RNA Hoxaas3 contributes to hypoxia-induced pulmonary artery smooth muscle cell proliferation

Aims

Long noncoding RNAs (lncRNAs) are involved in the regulation of vascular smooth muscle cells and cardiovascular pathology. However, the contribution of lncRNAs to pulmonary hypertension (PH) remains largely unknown. The over-proliferation of pulmonary artery smooth muscle cells (PASMCs) causes pulmonary arterial smooth muscle hypertrophy and stenosis of the pulmonary vascular lumen, resulting in PH. Here, we investigated the biological role of a novel lncRNA, Hoxa cluster antisense RNA 3 (Hoxaas3), in the regulation of cell proliferation in PH.

Methods and results

Hoxaas3 was up-regulated in the lung vasculature of hypoxic mice and in PASMCs under hypoxic conditions. Histone H3 Lysine 9 acetylation of Hoxaas3 promoted gene expression. Moreover, high expression of Hoxaas3 was associated with cell proliferation and modulated cell cycle distribution by up-regulating Homeobox a3 at the mRNA and protein levels.

Conclusion

This study defined the role and mechanism of action of Hoxaas3 in the regulation of cell proliferation in PH, which should facilitate the development of new therapeutic strategies for the treatment of this disease.

Follistatin-like 1 in development and human diseases

Follistatin-like 1 (FSTL1) is a secreted glycoprotein displaying expression changes during development and disease, among which cardiovascular disease, cancer, and arthritis. The cardioprotective role of FSTL1 has been intensively studied over the last years, though its mechanism of action remains elusive. FSTL1 is involved in multiple signaling pathways and biological processes, including vascularization and regulation of the immune response, a feature that complicates its study. Binding to the DIP2A, TLR4 and BMP receptors have been shown, but other molecular partners probably exist. During cancer progression and rheumatoid arthritis, controversial data have been reported with respect to the proliferative, apoptotic, migratory, and inflammatory effects of FSTL1. This controversy might reside in the extensive post-transcriptional regulation of FSTL1. The FSTL1 primary transcript also encodes for a microRNA (miR-198) in primates and multiple microRNA-binding sites are present in the 3'UTR. The switch between expression of the FSTL1 protein and miR-198 is an important regulator of tumour metastasis and wound healing. The glycosylation state of FSTL1 is a determinant of biological activity, in cardiomyocytes the glycosylated form promoting proliferation and the non-glycosylated working anti-apoptotic. Moreover, the glycosylation state shows differences between species and tissues which might underlie the differences observed in in vitro studies. Finally, regulation at the level of protein secretion has been described.

The Glucagon-Like Peptide-1 Receptor Agonist Liraglutide Improves Hypoxia-Induced Pulmonary Hypertension in Mice Partly via Normalization of Reduced ETB Receptor Expression

The glucagon-like peptide-1 receptor (GLP-1R) agonist liraglutide is an incretin hormone mimetic used in the treatment of diabetes. However, the effects of liraglutide on pulmonary hypertension (PH) and pulmonary endothelin (ET) system are unknown. Eight-week-old C57BL6/J mice were injected liraglutide or vehicle for 5 weeks. One week after injection, the mice were exposed to either room air (normoxia) or chronic hypoxia (10 % O2) for 4 weeks. The right ventricular systolic pressure (RVSP) was significantly higher in hypoxia + vehicle group than in normoxia + vehicle group. ET-1 mRNA expression in the lungs was comparable among all the groups. ETB mRNA and protein expression in the lungs was significantly lower in hypoxia + vehicle group than in normoxia + vehicle group. The above changes were normalized by liraglutide treatment. The expression of phospho-eNOS and phospho-AMPK proteins in the lungs was significantly higher in hypoxia + liraglutide group than in normoxia + vehicle group. We demonstrated for the first time that liraglutide effectively improved RVSP and RV hypertrophy in hypoxia-induced PH mice by activating eNOS through normalization of impaired ETB pathway and augmentation of AMPK pathway. Therefore, GLP-1R agonists can be promising therapeutic agents for PH.

CTRP9 regulates hypoxia-mediated human pulmonary artery smooth muscle cell proliferation, apoptosis and migration via TGF-β1/ERK1/2 signaling pathway

Hypoxia is an important risk factor for pulmonary arterial remodeling in pulmonary arterial hypertension (PAH). Vascular remodeling in hypoxia-induced PAH is driven by excessive proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs). The purpose of the present study was to explore the expression of CTRP9 in rats model of hypoxia-induced PAH and investigate the effects of CTRP9 on HPASMCs function in vitro and determine the underlying mechanisms. We established a rat model of hypoxic PAH, which showed a downregulation of CTRP9 expression. In HPASMCs cultured under the condition of hypoxia, treatment with CTRP9 notably restrained cell proliferation responses to hypoxia accompanied with decreased two biomarkers of cell proliferation Ki-67 and PCNA. Meanwhile, CTRP9 strikingly promoted hypoxia-mediated cell apoptosis as reflected by upregulation of Bax and downregulation of Bcl-2, as well as enhanced Caspase 3 activity. Additionally, CTRP9 treatment dramatically prevented the migratory potential by declined the expression of MMP-2 and MMP-9. Moreover treatment with CTRP9 augmented hypoxia-mediated differentiation by elevating the expression level of differentiation markers α-SMA and SM22. Mechanistically, anti-proliferative effects conferred by CTRP9 are mediated through suppression of TGF-β1/ERK1/2 pathway. Collectively, we identified CTRP9 as a novel mediator of PASMC growth in hypoxia-mediated PAH, indicating that CTRP9 in the pulmonary vasculature may be an underlying mechanism in the development of hypoxia-induced PAH. Our study, for the first time, established that CTRP9 plays a protective role of CTRP9 in pulmonary vascular remodeling, pointing to its potential clinical value for patients with PAH.