Caveolin-1-derived peptide limits development of pulmonary fibrosis

Endothelial caveolin and its scaffolding domain in cancer

Since the initial reports implicating caveolin-1 (CAV1) in neoplasia, the scientific community has made tremendous strides towards understanding how CAV1-dependent signaling and caveolae assembly modulate solid tumor growth. Once a solid neoplastic tumor reaches a certain size, it will increasingly rely on its stroma to meet the metabolic demands of the rapidly proliferating cancer cells, a limitation typically but not exclusively addressed via the formation of new blood vessels. Landmark studies using xenograft tumor models have highlighted the importance of stromal CAV1 during neoplastic blood vessel growth from preexisting vasculature, a process called angiogenesis, and helped identify endothelium-specific signaling events regulated by CAV1, such as vascular endothelial growth factor (VEGF) receptors as well as the endothelial nitric oxide (NO) synthase (eNOS) systems. This chapter provides a glimpse into the signaling events modulated by CAV1 and its scaffolding domain (CSD) during endothelial-specific aspects of neoplastic growth, such as vascular permeability, angiogenesis, and mechanotransduction.

Evaluation of Pirfenidone and Nintedanib in a Human Lung Model of Fibrogenesis

Introduction: Idiopathic pulmonary fibrosis (IPF) is a progressive, fatal lung disease with a poor prognosis and increasing incidence. Pirfenidone and nintedanib are the only approved treatments for IPF but have limited efficacy and their mechanisms of action are poorly understood. Here we have examined the effects of pirfenidone and nintedanib in a human model of lung fibrogenesis, and compared these with the putative anti-fibrotic compounds Lipoxin A4 (LXA4), and senicapoc, a K_Ca3.1 ion channel blocker. Methods: Early fibrosis was induced in cultured human lung parenchyma using TGFβ1 for 7 days, ± pirfenidone, nintedanib, or LXA4. Pro-fibrotic responses were examined by RT-PCR, immunohistochemistry and soluble collagen secretion. Results: Thirty six out of eighty four IPF and fibrosis-associated genes tested were significantly upregulated by TGFβ1 in human lung parenchyma with a ≥0.5 log2FC (n = 32). Nintedanib (n = 13) reduced the mRNA expression of 14 fibrosis-associated genes including MMPs (MMP1,-4,-13,-14), integrin α2, CXCR4 and PDGFB, but upregulated α-smooth muscle actin (αSMA). Pirfenidone only reduced mRNA expression for MMP3 and -13. Senicapoc (n = 11) previously attenuated the expression of 28 fibrosis-associated genes, including αSMA, several growth factors, collagen type III, and αV/β6 integrins. Pirfenidone and nintedanib significantly inhibited TGFβ1-induced fibroblast proliferation within the tissue, but unlike senicapoc, neither pirfenidone nor nintedanib prevented increases in tissue αSMA expression. LXA4 was ineffective. Conclusions: Pirfenidone and nintedanib demonstrate modest anti-fibrotic effects and provide a benchmark for anti-fibrotic activity of new drugs in human lung tissue. Based on these data, we predict that the K_Ca3.1 blocker senicapoc will show greater benefit than either of these licensed drugs in IPF.

A Landscape of lncRNA Expression Profile and the Predictive Value of a Candidate lncRNA for Silica-Induced Pulmonary Fibrosis

Silicosis is the most common type of pneumoconiosis with the fastest progress and the most serious harm. At present, there is still a lack of effective treatment for silicosis, and the molecular mechanism of silicosis is very complex, which is not completely clear. This study aimed to identify crucial long noncoding RNA (lncRNA)-mRNA networks for silica-induced pulmonary fibrosis using microarray data from Gene Expression Omnibus database, including human lung epithelial cells Beas-2B and continuously exposed to 5 μg/mL amorphous silica nanoparticles for 40 passages. Differently expressed genes were calculated by "DESeq2" R package. Then we selected the differently expressed mRNAs (DEmRNAs) and differently expressed long noncoding RNAs (DElncRNAs) data construct lncRNA-mRNA coexpression network using weighted gene coexpression network analysis (WCGNA). A total of 1140 DEmRNA and 1406 DElncRNAs were identified, including 20 upregulated DEmRNAs, 1120 downregulated DEmRNAs as well as 213 upregulated DElncRNAs and 1193 downregulated DElncRNAs. Furthermore, we demonstrate that lncRNA AK131029 was specifically overexpressed in silicosis. Loss-of-function assay indicated that silencing AK131029 of inhibited cell proliferation in human lung fibroblast cells. In conclusion, this study preliminarily indicates that lncRNA AK131029 may play a role in pulmonary fibrosis.

MG53/CAV1 regulates transforming growth factor-β1 signaling-induced atrial fibrosis in atrial fibrillation

Atrial fibrosis plays a significant role in the development of atrial fibrillation (AF). Previously, we showed that mitsugumin 53 (MG53) regulates TGF-β1 signaling pathway-induced atrial fibrosis. Recent studies have shown that caveolin-1 (CAV1) is an important anti-fibrosis signaling mediator that inhibits the TGF-β1 signaling pathway. Here, we further study the mechanism underlying the related action of MG53 and CAV1. We demonstrate that CAV1 expression was decreased while MG53 expression was increased in atrial tissue from AF patients. In cultured atrial fibroblasts, MG53 depletion by siRNA caused CAV1 upregulation and TGF-β1/SMAD2 signaling pathway downregulation, while MG53 overexpression via adenovirus had the opposite effect. CAV1 inactivated the TGF-β1/SMAD2 signaling pathway. In addition, using an Ang II-induced fibrosis model, we show that MG53 regulates TGF-β1 signaling via CAV1. Therefore, CAV1 is critical for the MG53 regulation of TGF-β1 signaling pathway-induced atrial fibrosis in AF. These findings reveal the related underlying mechanism of action of MG53 and CAV1 and provide a potential therapeutic target for fibrosis and AF.

Caveolin-1 scaffolding domain peptide regulates glucose metabolism in lung fibrosis

Increased metabolism distinguishes myofibroblasts or fibrotic lung fibroblasts (fLfs) from the normal lung fibroblasts (nLfs). The mechanism of metabolic activation in fLfs has not been fully elucidated. Furthermore, the antifibrogenic effects of caveolin-1 scaffolding domain peptide CSP/CSP7 involving metabolic reprogramming in fLfs are unclear. We therefore analyzed lactate and succinate levels, as well as the expression of glycolytic enzymes and hypoxia inducible factor-1α (HIF-1α). Lactate and succinate levels, as well as the basal expression of glycolytic enzymes and HIF-1α, were increased in fLfs. These changes were reversed following restoration of p53 or its transcriptional target microRNA-34a (miR-34a) expression in fLfs. Conversely, inhibition of basal p53 or miR-34a increased glucose metabolism, glycolytic enzymes, and HIF-1α in nLfs. Treatment of fLfs or mice having bleomycin- or Ad-TGF-β1-induced lung fibrosis with CSP/CSP7 reduced the expression of glycolytic enzymes and HIF-1α. Furthermore, inhibition of p53 or miR-34a abrogated CSP/CSP7-mediated restoration of glycolytic flux in fLfs in vitro and in mice with pulmonary fibrosis and lacking p53 or miR-34a expression in fibroblasts in vivo. Our data indicate that dysregulation of glucose metabolism in fLfs is causally linked to loss of basal expression of p53 and miR-34a. Treatment with CSP/CSP7 constrains aberrant glucose metabolism through restoration of p53 and miR-34a.

Epithelial Dysfunction in Lung Diseases: Effects of Amino Acids and Potential Mechanisms

Lung diseases affect millions of individuals all over the world. Various environmental factors, such as toxins, chemical pollutants, detergents, viruses, bacteria, microbial dysbiosis, and allergens, contribute to the development of respiratory disorders. Exposure to these factors activates stress responses in host cells and disrupt lung homeostasis, therefore leading to dysfunctional epithelial barriers. Despite significant advances in therapeutic treatments for lung diseases in the last two decades, novel interventional targets are imperative, considering the side effects and limited efficacy in patients treated with currently available drugs. Nutrients, such as amino acids (e.g., arginine, glutamine, glycine, proline, taurine, and tryptophan), peptides, and bioactive molecules, have attracted more and more attention due to their abilities to reduce oxidative stress, inhibit apoptosis, and regulate immune responses, thereby improving epithelial barriers. In this review, we summarize recent advances in amino acid metabolism in the lungs, as well as multifaceted functions of amino acids in attenuating inflammatory lung diseases based on data from studies with both human patients and animal models. The underlying mechanisms for the effects of physiological amino acids are likely complex and involve cell signaling, gene expression, and anti-oxidative reactions. The beneficial effects of amino acids are expected to improve the respiratory health and well-being of humans and other animals. Because viruses (e.g., coronavirus) and environmental pollutants (e.g., PM2.5 particles) induce severe damage to the lungs, it is important to determine whether dietary supplementation or intravenous administration of individual functional amino acids (e.g., arginine-HCl, citrulline, N-acetylcysteine, glutamine, glycine, proline and tryptophan) or their combinations to affected subjects may alleviate injury and dysfunction in this vital organ.

The contribution of animal models to understanding the role of the immune system in human idiopathic pulmonary fibrosis

Pulmonary fibrosis occurs in a heterogeneous group of lung disorders and is characterised by an excessive deposition of extracellular matrix proteins within the pulmonary interstitium, leading to impaired gas transfer and a loss of lung function. In the past 10 years, there has been a dramatic increase in our understanding of the immune system and how it contributes to fibrogenic processes within the lung. This review will compare some of the models used to investigate the pathogenesis and treatment of pulmonary fibrosis, in particular those used to study immune cell pathogenicity in idiopathic pulmonary fibrosis, highlighting their advantages and disadvantages in dissecting human disease.

Pulmonary Artery Thrombosis: A Diagnosis That Strives for Its Independence

According to a widespread theory, thrombotic masses are not formed in the pulmonary artery (PA) but result from migration of blood clots from the venous system. This concept has prevailed in clinical practice for more than a century. However, a new technologic era has brought forth more diagnostic possibilities, and it has been shown that thrombotic masses in the PA could, in many cases, be found without any obvious source of emboli. Chronic obstructive pulmonary disease, asthma, sickle cell anemia, emergency and elective surgery, viral pneumonia, and other conditions could be complicated by PA thrombosis development without concomitant deep vein thrombosis (DVT). Different pathologies have different causes for local PA thrombotic process. As evidenced by experimental results and clinical observations, endothelial and platelet activation are the crucial mechanisms of this process. Endothelial dysfunction can impair antithrombotic function of the arterial wall through downregulation of endothelial nitric oxide synthase (eNOS) or via stimulation of adhesion receptor expression. Hypoxia, proinflammatory cytokines, or genetic mutations may underlie the procoagulant phenotype of the PA endothelium. Both endotheliocytes and platelets could be activated by protease mediated receptor (PAR)- and receptors for advanced glycation end (RAGE)-dependent mechanisms. Hypoxia, in particular induced by high altitudes, could play a role in thrombotic complications as a trigger of platelet activity. In this review, we discuss potential mechanisms of PA thrombosis in situ.

Inhalation of Tetrandrine-hydroxypropyl-β-cyclodextrin Inclusion Complexes for Pulmonary Fibrosis Treatment

Pulmonary fibrosis (PF) is a kind of interstitial lung disease with the features of progressive and often fatal dyspnea. Tetrandrine (TET) is the major active constituent of Chinese herbal Stephania tetrandra S. Moore, which has already applied clinically to treat rheumatism, lung cancer, and silicosis. In this work, a tetrandrine-hydroxypropyl-β-cyclodextrin inclusion compound (TET-HP-β-CD) was developed for the treatment of pulmonary fibrosis via inhalation administration. TET-HP-β-CD was prepared by the freeze-drying method and identified using the cascade impactor, differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared spectrum (FT-IR). A bleomycin-induced pulmonary fibrosis rat model was used to assess the effects of inhaled TET and TET-HP-β-CD. Animal survival, hydroxyproline content in the lungs, and lung histology were detected. The results showed that inhalation of TET-HP-β-CD alleviated inflammation and fibrosis, limited the accumulation of hydroxyproline in the lungs, regulated protein expression in PF development, and improved postoperative survival. Moreover, nebulized delivery of TET-HP-β-CD accumulated chiefly in the lungs and limited systemic distribution compared with intravenous administration. The present results indicated that inhalation of TET-HP-β-CD is an attractive candidate for the treatment of pulmonary fibrosis.

Development of an Excipient-Free Peptide Dry Powder Inhalation for the Treatment of Pulmonary Fibrosis

The caveolin scaffolding domain peptide (CSP) is being developed for the therapeutic intervention of a lethal lung disease, idiopathic pulmonary fibrosis. While direct respiratory delivery of CSP7 (a 7-mer fragment of CSP) is considered an effective route, proper formulation and processing of the peptide are required. First, air-jet milling technology was performed in order to micronize the neat peptide powder. Next, the fine particles were subjected to a stability study with physical and chemical characterizations. In addition, the in vivo efficacy of processed CSP7 powder was evaluated in an animal model of lung fibrosis. The results revealed that, with jet milling, the particle size of CSP7 was reduced to a mass median aerodynamic diameter of 1.58 ± 0.1 μm and 93.3 ± 3.3% fine particle fraction, optimal for deep lung delivery. A statistically significant reduction of collagen was observed in diseased lung tissues of mice that received CSP7 powder for inhalation. The particles remained chemically and physically stable after micronization and during storage. This work demonstrated that jet milling is effective in the manufacturing of a stable, excipient-free CSP7 inhalation powder for the treatment of pulmonary fibrosis.