HDAC inhibitors as antifibrotic drugs in cardiac and pulmonary fibrosis

Corneal fibrosis: From in vitro models to current and upcoming drug and gene medicines

Fibrotic diseases are characterised by myofibroblast differentiation, uncontrolled pathological extracellular matrix accumulation, tissue contraction, scar formation and, ultimately tissue / organ dysfunction. The cornea, the transparent tissue located on the anterior chamber of the eye, is extremely susceptible to fibrotic diseases, which cause loss of corneal transparency and are often associated with blindness. Although topical corticosteroids and antimetabolites are extensively used in the management of corneal fibrosis, they are associated with glaucoma, cataract formation, corneoscleral melting and infection, imposing the need of far more effective therapies. Herein, we summarise and discuss shortfalls and recent advances in in vitro models (e.g. transforming growth factor-β (TGF-β) / ascorbic acid / interleukin (IL) induced) and drug (e.g. TGF-β inhibitors, epigenetic modulators) and gene (e.g. gene editing, gene silencing) therapeutic strategies in the corneal fibrosis context. Emerging therapeutical agents (e.g. neutralising antibodies, ligand traps, receptor kinase inhibitors, antisense oligonucleotides) that have shown promise in clinical setting but have not yet assessed in corneal fibrosis context are also discussed.

Sodium valproate treatment reverses endothelial dysfunction in aorta from rabbits with acute myocardial infarction

Sodium valproate (VPA), a histone deacetylase (HDAC) inhibitor, could be a promising candidate to treat acute myocardial infarction (AMI). In this study, AMI was induced in New Zealand White rabbits by occluding the left circumflex coronary artery for 1 h, followed by reperfusion. The animals were distributed into three experimental groups: the sham-operated group (SHAM), the AMI group and the AMI + VPA group (AMI treated with VPA 500 mg/kg/day). After 5 weeks, abdominal aorta was removed and used for isometric recording of tension in organ baths or protein expression by Western blot, and plasma for the determination of nitrate/nitrite (NOx) levels by colorimetric assay. Our results indicated that AMI induced a reduction of the endothelium-dependent response to acetylcholine without modifying the endothelium-independent response to sodium nitroprusside, leading to endothelial dysfunction. VPA treatment reversed AMI-induced endothelial dysfunction and even increased NO sensitivity in vascular smooth muscle. This response was consistent with an antioxidant effect of VPA, as it was able to reverse the superoxide dismutase 1 (SOD 1) down-regulation induced by AMI. Our experiments also ruled out that the VPA mechanism was related to eNOS, iNOS, sGC and arginase expression or changes in NOx plasma levels. Therefore, we conclude that VPA improves vasodilation by increasing NO bioavailability, likely due to its antioxidant effect. Since endothelial dysfunction was closely related to AMI, VPA treatment could increase aortic blood flow, making it a potential agent in reperfusion therapy that can prevent the vascular damage.

O-GlcNAc regulates anti-fibrotic genes in lung fibroblasts through EZH2

Epigenetic modifications are involved in fibrotic diseases, such as idiopathic pulmonary fibrosis (IPF), and contribute to the silencing of anti-fibrotic genes. H3K27me3, a key repressive histone mark, is catalysed by the methyltransferase enhancer of Zeste homologue 2 (EZH2), which is regulated by the post-translational modification, O-linked N-Acetylglucosamine (O-GlcNAc). In this study, we explored the effects of O-GlcNAc and EZH2 on the expression of antifibrotic genes, cyclooxygenase-2 (Cox2) and Heme Oxygenase (Homx1). The expression of Cox2 and Hmox1 was examined in primary IPF or non-IPF lung fibroblasts with or without EZH2 inhibitor EZP6438, O-GlcNAc transferase (OGT) inhibitor (OSMI-1) or O-GlcNAcase (OGA) inhibitor (thiamet G). Non-IPF cells were also subjected to TGF-β1 with or without OGT inhibition. The reduced expression of Cox2 and Hmox1 in IPF lung fibroblasts is restored by OGT inhibition. In non-IPF fibroblasts, TGF-β1 treatment reduces Cox2 and Hmox1 expression, which was restored by OGT inhibition. ChIP assays demonstrated that the association of H3K27me3 is reduced at the Cox2 and Hmox1 promoter regions following OGT or EZH2 inhibition. EZH2 levels and stability were decreased by reducing O-GlcNAc. Our study provided a novel mechanism of O-GlcNAc modification in regulating anti-fibrotic genes in lung fibroblasts and in the pathogenesis of IPF.

Mechanisms of mesothelial cell response to viral infections: HDAC1-3 inhibition blocks poly(I:C)-induced type I interferon response and modulates the mesenchymal/inflammatory phenotype

Infectious peritonitis is a leading cause of peritoneal functional impairment and a primary factor for therapy discontinuation in peritoneal dialysis (PD) patients. Although bacterial infections are a common cause of peritonitis episodes, emerging evidence suggests a role for viral pathogens. Toll-like receptors (TLRs) specifically recognize conserved pathogen-associated molecular patterns (PAMPs) from bacteria, viruses, and fungi, thereby orchestrating the ensuing inflammatory/immune responses. Among TLRs, TLR3 recognizes viral dsRNA and triggers antiviral response cascades upon activation. Epigenetic regulation, mediated by histone deacetylase (HDAC), has been demonstrated to control several cellular functions in response to various extracellular stimuli. Employing epigenetic target modulators, such as epidrugs, is a current therapeutic option in several cancers and holds promise in treating viral diseases. This study aims to elucidate the impact of TLR3 stimulation on the plasticity of human mesothelial cells (MCs) in PD patients and to investigate the effects of HDAC1-3 inhibition. Treatment of MCs from PD patients with the TLR3 agonist polyinosinic:polycytidylic acid (Poly(I:C)), led to the acquisition of a bona fide mesothelial-to-mesenchymal transition (MMT) characterized by the upregulation of mesenchymal genes and loss of epithelial-like features. Moreover, Poly(I:C) modulated the expression of several inflammatory cytokines and chemokines. A quantitative proteomic analysis of MCs treated with MS-275, an HDAC1-3 inhibitor, unveiled altered expression of several proteins, including inflammatory cytokines/chemokines and interferon-stimulated genes (ISGs). Treatment with MS-275 facilitated MMT reversal and inhibited the interferon signature, which was associated with reduced STAT1 phosphorylation. However, the modulation of inflammatory cytokine/chemokine production was not univocal, as IL-6 and CXCL8 were augmented while TNF-α and CXCL10 were decreased. Collectively, our findings underline the significance of viral infections in acquiring a mesenchymal-like phenotype by MCs and the potential consequences of virus-associated peritonitis episodes for PD patients. The observed promotion of MMT reversal and interferon response inhibition by an HDAC1-3 inhibitor, albeit without a general impact on inflammatory cytokine production, has translational implications deserving further analysis.

N-(2-Aminophenyl)-benzamide Inhibitors of Class I HDAC Enzymes with Antiproliferative and Antifibrotic Activity

Inhibitors of histone deacetylases (HDACs) have received special attention as novel anticancer agents. Among various types of synthetic inhibitors, benzamides constitute an important class, and one is an approved drug (chidamide). Here, we present a novel class of HDAC inhibitors containing the N-(2-aminophenyl)-benzamide functionality as the zinc-binding group linked to various cap groups, including the amino acids pyroglutamic acid and proline. We have identified benzamides that inhibit HADC1 and HDAC2 at nanomolar concentrations, with antiproliferative activity at micromolar concentrations against A549 and SF268 cancer cell lines. Docking studies shed light on the mode of binding of benzamide inhibitors to HDAC1, whereas cellular analysis revealed downregulated expression of EGFR mRNA and protein. Two benzamides were investigated in a mouse model of bleomycin-induced pulmonary fibrosis, and both showed efficacy on a preventative dosing schedule. N-(2-Aminophenyl)-benzamide inhibitors of class I HDACs might lead to new approaches for treating fibrotic disorders.

Synergistic Power of Piceatannol and/or Vitamin D in Bleomycin-Induced Pulmonary Fibrosis In Vivo: A Preliminary Study

Oxidative stress and epigenetic alterations, including the overexpression of all class I and II histone deacetylases (HDACs), particularly HDAC2 and HDAC4, have been identified as key molecular mechanisms driving pulmonary fibrosis. Treatment with piceatannol (PIC) or vitamin D (Vit D) has previously exhibited mitigating impacts in pulmonary fibrosis models. The present study investigated the effects of PIC, Vit D, or a combination (PIC-Vit D) on the expression of HDAC2, HDAC4, and transforming growth factor-beta (TGF-β) in the lungs; the phosphatidylinositide-3-kinase (PI3K)/AKT signaling pathway; and the antioxidant status of the lungs. The objective was to determine if the treatments had protective mechanisms against pulmonary fibrosis caused by bleomycin (BLM) in rats. Adult male albino rats were given a single intratracheal dosage of BLM (10 mg/kg) to induce pulmonary fibrosis. PIC (15 mg/kg/day, oral (p.o.)), Vit D (0.5 μg/kg/day, intraperitoneal (i.p.)), or PIC-Vit D (15 mg/kg/day, p.o. plus 0.5 μg/kg/day, i.p.) were given the day following BLM instillation and maintained for 14 days. The results showed that PIC, Vit D, and PIC-Vit D significantly improved the histopathological sections; downregulated the expression of HDAC2, HDAC4, and TGF-β in the lungs; inhibited the PI3K/AKT signaling pathway; decreased extracellular matrix (ECM) deposition including collagen type I and alpha smooth muscle actin (α-SMA); and increased the antioxidant capacity of the lungs by increasing the levels of glutathione (GSH) that had been reduced and decreasing the levels of malondialdehyde (MDA) compared with the BLM group at a p-value less than 0.05. The concomitant administration of PIC and Vit D had a synergistic impact that was greater than the impact of monotherapy with either PIC or Vit D. PIC, Vit D, and PIC-Vit D exhibited a notable protective effect through their antioxidant effects, modulation of the expression of HDAC2, HDAC4, and TGF-β in the lungs, and suppression of the PI3K/AKT signaling pathway.

Epigenetic Regulation of Fibroblasts and Crosstalk between Cardiomyocytes and Non-Myocyte Cells in Cardiac Fibrosis

Epigenetic mechanisms and cell crosstalk have been shown to play important roles in the initiation and progression of cardiac fibrosis. This review article aims to provide a thorough overview of the epigenetic mechanisms involved in fibroblast regulation. During fibrosis, fibroblast epigenetic regulation encompasses a multitude of mechanisms, including DNA methylation, histone acetylation and methylation, and chromatin remodeling. These mechanisms regulate the phenotype of fibroblasts and the extracellular matrix composition by modulating gene expression, thereby orchestrating the progression of cardiac fibrosis. Moreover, cardiac fibrosis disrupts normal cardiac function by imposing myocardial mechanical stress and compromising cardiac electrical conduction. This review article also delves into the intricate crosstalk between cardiomyocytes and non-cardiomyocytes in the heart. A comprehensive understanding of the mechanisms governing epigenetic regulation and cell crosstalk in cardiac fibrosis is critical for the development of effective therapeutic strategies. Further research is warranted to unravel the precise molecular mechanisms underpinning these processes and to identify potential therapeutic targets.

Multifaced roles of desmoplastic reaction and fibrosis in pancreatic cancer progression: Current understanding and future directions

Desmoplastic reaction is a fibrosis reaction that is characterized by a large amount of dense extracellular matrix (ECM) and dense fibrous stroma. Fibrotic stroma around the tumor has several different components, including myofibroblasts, collagen, and other ECM molecules. This stromal reaction is a natural response to the tissue injury process, and fibrosis formation is a key factor in pancreatic cancer development. The fibrotic stroma of pancreatic cancer is associated with tumor progression, metastasis, and poor prognosis. Reportedly, multiple processes are involved in fibrosis, which is largely associated with the upregulation of various cytokines, chemokines, matrix metalloproteinases, and other growth factors that promote tumor growth and metastasis. Fibrosis is also associated with immunosuppressive cell recruitment, such as regulatory T cells (Tregs) with suppressing function to antitumor immunity. Further, dense fibrosis restricts the flow of nutrients and oxygen to the tumor cells, which can contribute to drug resistance. Furthermore, the dense collagen matrix can act as a physical barrier to block the entry of drugs into the tumor, thereby further contributing to drug resistance. Thus, understanding the mechanism of desmoplastic reaction and fibrosis in pancreatic cancer will open an avenue to innovative medicine and improve the prognosis of patients suffering from this disease.

Discovery of HDAC6, HDAC8, and 6/8 Inhibitors and Development of Cell-Based Drug Screening Models for the Treatment of TGF-β-Induced Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis is incurable, and its progression is difficult to control and thus can lead to pulmonary deterioration. Pan-histone deacetylase inhibitors such as SAHA have shown potential for modulating pulmonary fibrosis yet with off-target effects. Therefore, selective HDAC inhibitors would be beneficial for reducing side effects. Toward this goal, we designed and synthesized 24 novel HDAC6, HDAC8, or dual HDAC6/8 inhibitors and established a two-stage screening platform to rapidly screen for HDAC inhibitors that effectively mitigate TGF-β-induced pulmonary fibrosis. The first stage consisted of a mouse NIH-3T3 fibroblast prescreen and yielded five hits. In the second stage, human pulmonary fibroblasts (HPFs) were used, and four out of the five hits were tested for caco-2 permeability and liver microsome stability to give two potential leads: J27644 (15) and 20. This novel two-stage screen platform will accelerate the discovery and reduce the cost of developing HDAC inhibitors to mitigate TGF-β-induced pulmonary fibrosis.

Bioactive Compounds and Cardiac Fibrosis: Current Insight and Future Prospect

Cardiac fibrosis is a pathological condition characterized by excessive deposition of collagen and other extracellular matrix components in the heart. It is recognized as a major contributor to the development and progression of heart failure. Despite significant research efforts in characterizing and identifying key molecular mechanisms associated with myocardial fibrosis, effective treatment for this condition is still out of sight. In this regard, bioactive compounds have emerged as potential therapeutic antifibrotic agents due to their anti-inflammatory and antioxidant properties. These compounds exhibit the ability to modulate fibrogenic processes by inhibiting the production of extracellular matrix proteins involved in fibroblast to myofibroblast differentiation, or by promoting their breakdown. Extensive investigation of these bioactive compounds offers new possibilities for preventing or reducing cardiac fibrosis and its detrimental consequences. This comprehensive review aims to provide a thorough overview of the mechanisms underlying cardiac fibrosis, address the limitations of current treatment strategies, and specifically explore the potential of bioactive compounds as therapeutic interventions for the treatment and/or prevention of cardiac fibrosis.

Biologic drugs in the treatment of chronic inflammatory pulmonary diseases: recent developments and future perspectives

Chronic inflammatory diseases of the lung are some of the leading causes of mortality and significant morbidity worldwide. Despite the tremendous burden these conditions put on global healthcare, treatment options for most of these diseases remain scarce. Inhaled corticosteroids and beta-adrenergic agonists, while effective for symptom control and widely available, are linked to severe and progressive side effects, affecting long-term patient compliance. Biologic drugs, in particular peptide inhibitors and monoclonal antibodies show promise as therapeutics for chronic pulmonary diseases. Peptide inhibitor-based treatments have already been proposed for a range of diseases, including infectious disease, cancers and even Alzheimer disease, while monoclonal antibodies have already been implemented as therapeutics for a range of conditions. Several biologic agents are currently being developed for the treatment of asthma, chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis and pulmonary sarcoidosis. This article is a review of the biologics already employed in the treatment of chronic inflammatory pulmonary diseases and recent progress in the development of the most promising of those treatments, with particular focus on randomised clinical trial outcomes.

The Role of Histone Deacetylases in Acute Lung Injury-Friend or Foe

Acute lung injury (ALI), caused by intrapulmonary or extrapulmonary factors such as pneumonia, shock, and sepsis, eventually disrupts the alveolar-capillary barrier, resulting in diffuse pulmonary oedema and microatasis, manifested by refractory hypoxemia, and respiratory distress. Not only is ALI highly lethal, but even if a patient survives, there are also multiple sequelae. Currently, there is no better treatment than supportive care, and we urgently need to find new targets to improve ALI. Histone deacetylases (HDACs) are epigenetically important enzymes that, together with histone acetylases (HATs), regulate the acetylation levels of histones and non-histones. While HDAC inhibitors (HDACis) play a therapeutic role in cancer, inflammatory, and neurodegenerative diseases, there is also a large body of evidence suggesting the potential of HDACs as therapeutic targets in ALI. This review explores the unique mechanisms of HDACs in different cell types of ALI, including macrophages, pulmonary vascular endothelial cells (VECs), alveolar epithelial cells (AECs), and neutrophils.

Mesenchymal cells in the Lung: Evolving concepts and their role in fibrosis

Mesenchymal cells in the lung are crucial during development, but also contribute to the pathogenesis of fibrotic disorders, including idiopathic pulmonary fibrosis (IPF), the most common and deadly form of fibrotic interstitial lung diseases. Originally thought to behave as supporting cells for the lung epithelium and endothelium with a singular function of producing basement membrane, mesenchymal cells encompass a variety of cell types, including resident fibroblasts, lipofibroblasts, myofibroblasts, smooth muscle cells, and pericytes, which all occupy different anatomic locations and exhibit diverse homeostatic functions in the lung. During injury, each of these subtypes demonstrate remarkable plasticity and undergo varying capacity to proliferate and differentiate into activated myofibroblasts. Therefore, these cells secrete high levels of extracellular matrix (ECM) proteins and inflammatory cytokines, which contribute to tissue repair, or in pathologic situations, scarring and fibrosis. Whereas epithelial damage is considered the initial trigger that leads to lung injury, lung mesenchymal cells are recognized as the ultimate effector of fibrosis and attempts to better understand the different functions and actions of each mesenchymal cell subtype will lead to a better understanding of why fibrosis develops and how to better target it for future therapy. This review summarizes current findings related to various lung mesenchymal cells as well as signaling pathways, and their contribution to the pathogenesis of pulmonary fibrosis.

Absence of HDAC3 by Matrix Stiffness Promotes Chromatin Remodeling and Fibroblast Activation in Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic and fatal disease characterized by progressive and irreversible lung scarring associated with persistent activation of fibroblasts. Epigenetics could integrate diverse microenvironmental signals, such as stiffness, to direct persistent fibroblast activation. Histone modifications by deacetylases (HDAC) may play an essential role in the gene expression changes involved in the pathological remodeling of the lung. Particularly, HDAC3 is crucial for maintaining chromatin and regulating gene expression, but little is known about its role in IPF. In the study, control and IPF-derived fibroblasts were used to determine the influence of HDAC3 on chromatin remodeling and gene expression associated with IPF signature. Additionally, the cells were grown on hydrogels to mimic the stiffness of a fibrotic lung. Our results showed a decreased HDAC3 in the nucleus of IPF fibroblasts, which correlates with changes in nucleus size and heterochromatin loss. The inhibition of HDAC3 with a pharmacological inhibitor causes hyperacetylation of H3K9 and provokes an increased expression of Col1A1, ACTA2, and p21. Comparable results were found in hydrogels, where matrix stiffness promotes the loss of nuclear HDAC3 and increases the profibrotic signature. Finally, latrunculin b was used to confirm that changes by stiffness depend on the mechanotransduction signals. Together, these results suggest that HDAC3 could be a link between epigenetic mechanisms and the fibrotic microenvironment.

HDAC6 regulates human erythroid differentiation through modulation of JAK2 signalling

Among histone deacetylases, HDAC6 is unusual in its cytoplasmic localization. Its inhibition leads to hyperacetylation of non-histone proteins, inhibiting cell cycle, proliferation and apoptosis. Ricolinostat (ACY-1215) is a selective inhibitor of the histone deacetylase HDAC6 with proven efficacy in the treatment of malignant diseases, but anaemia is one of the most frequent side effects. We investigated here the underlying mechanisms of this erythroid toxicity. We first confirmed that HDAC6 was strongly expressed at both RNA and protein levels in CD34⁺ -cells-derived erythroid progenitors. ACY-1215 exposure on CD34⁺ -cells driven in vitro towards the erythroid lineage led to a decreased cell count, an increased apoptotic rate and a delayed erythroid differentiation with accumulation of weakly hemoglobinized immature erythroblasts. This was accompanied by drastic changes in the transcriptomic profile of primary cells as shown by RNAseq. In erythroid cells, ACY-1215 and shRNA-mediated HDAC6 knockdown inhibited the EPO-dependent JAK2 phosphorylation. Using acetylome, we identified 14-3-3ζ, known to interact directly with the JAK2 negative regulator LNK, as a potential HDAC6 target in erythroid cells. We confirmed that 14-3-3ζ was hyperacetylated after ACY-1215 exposure, which decreased the 14-3-3ζ/LNK interaction while increased LNK ability to interact with JAK2. Thus, in addition to its previously described role in the enucleation of mouse fetal liver erythroblasts, we identified here a new mechanism of HDAC6-dependent control of erythropoiesis through 14-3-3ζ acetylation level, LNK availability and finally JAK2 activation in response to EPO, which is crucial downstream of EPO-R activation for human erythroid cell survival, proliferation and differentiation.

Epigenetics alternation in lung fibrosis and lung cancer

Respiratory disease including interstitial lung diseases (ILDs) and lung cancer is a group of devastating diseases that linked with increased morbidity and healthcare burden. However, respiratory diseases cannot be fully explained by the alternation of genetic information. Genetic studies described that epigenetic mechanisms also participate to transmit genetic information. Recently, many studies demonstrated the role of altered epigenetic modification in the pathogenesis of lung cancer and pulmonary fibrosis. Due to lacking effective medication, the underlying pathophysiological processes and causal relationships of lung diseases with epigenetic mechanisms still need to be better understood. Our present review provided a systematic revision of current knowledge concerning diverse epigenetic aberrations in major lung diseases, with special emphasis on DNA methylation, histone modifications, lncRNAs profiles, telomere patterns, as well as chromatin-remodelling complexes. We believed that a new target therapy for lung disease based on findings of the involved epigenetic pathway is a promising future direction.

A phase I/II study of ivaltinostat combined with gemcitabine and erlotinib in patients with untreated locally advanced or metastatic pancreatic adenocarcinoma

This phase I/II study evaluated the safety and efficacy of a new histone deacetylase (HDAC) inhibitor, ivaltinostat, in combination with gemcitabine and erlotinib for advanced pancreatic ductal adenocarcinoma (PDAC). Patients diagnosed with unresectable, histologically confirmed PDAC who had not undergone previous therapy were eligible. Phase I had a 3 + 3 dose escalation design to determine the maximum tolerable dose (MTD) of ivaltinostat (intravenously on days 1, 8 and 15) with gemcitabine (1000 mg/m2 intravenously on days 1, 8 and 15) and erlotinib (100 mg/day, orally) for a 28-day cycle. In phase II, patients received a six-cycle treatment with the MTD of ivaltinostat determined in phase I. The primary endpoint was the objective response rate (ORR). Secondary endpoints included overall survival (OS), disease control rate (DCR) and progression-free survival (PFS). The MTD of ivaltinostat for the phase II trial was determined to be 250 mg/m2 . In phase II, 24 patients were enrolled. The median OS and PFS were 8.6 (95% confidence interval [CI]: 5.3-11.2) and 5.3 months (95% CI: 3.7-5.8). Of the 16 patients evaluated for response, ORR and DCR were 25.0% and 93.8% with a median OS/PFS of 10.8 (95% CI: 8.3-16.7)/5.8 (95% CI: 4.6-6.7) months. Correlative studies showed that mutation burden detected by cfDNA and specific blood markers such as TIMP1, pro-MMP10, PECAM1, proMMP-2 and IGFBP1 were associated with clinical outcomes. Although the result of a small study, a combination of ivaltinostat, gemcitabine and erlotinib appeared to be a potential treatment option for advanced PDAC.

A transcriptomics-based meta-analysis identifies a cross-tissue signature for sarcoidosis

Sarcoidosis is a granulomatous disease of unknown etiology, immunologically characterized by a Th1 immune response. Transcriptome-wide expression studies in various types of sarcoid tissues contributed to better understanding of disease mechanisms. We performed a systematic database search on Gene Expression Omnibus (GEO) and utilized transcriptomic data from blood and sarcoidosis-affected tissues in a meta-analysis to identify a cross-tissue, cross-platform signature. Datasets were further separated into training and testing sets for development of a diagnostic classifier for sarcoidosis. A total of 690 differentially expressed genes were identified in the analysis among various tissues. 29 of the genes were robustly associated with sarcoidosis in the meta-analysis both in blood and in lung-associated tissues. Top genes included LINC01278 (P = 3.11 × 10^–13), GBP5 (P = 5.56 × 10^–07), and PSMB9 (P = 1.11 × 10^–06). Pathway enrichment analysis revealed activated IFN-γ, IL-1, and IL-18, autophagy, and viral infection response. IL-17 was observed to be enriched in peripheral blood specific signature genes. A 16-gene classifier achieved excellent performance in the independent validation data (AUC 0.711–0.964). This study provides a cross-tissue meta-analysis for expression profiles of sarcoidosis and identifies a diagnostic classifier that potentially can complement more invasive procedures.

Prospects and Challenges of Electrospun Cell and Drug Delivery Vehicles to Correct Urethral Stricture

Current therapeutic modalities to treat urethral strictures are associated with several challenges and shortcomings. Therefore, significant strides have been made to develop strategies with minimal side effects and the highest therapeutic potential. In this framework, electrospun scaffolds incorporated with various cells or bioactive agents have provided promising vistas to repair urethral defects. Due to the biomimetic nature of these constructs, they can efficiently mimic the native cells’ niches and provide essential microenvironmental cues for the safe transplantation of multiple cell types. Furthermore, these scaffolds are versatile platforms for delivering various drug molecules, growth factors, and nucleic acids. This review discusses the recent progress, applications, and challenges of electrospun scaffolds to deliver cells or bioactive agents during the urethral defect repair process. First, the current status of electrospinning in urethral tissue engineering is presented. Then, the principles of electrospinning in drug and cell delivery applications are reviewed. Finally, the recent preclinical studies are summarized and the current challenges are discussed.

Novel Therapies for the Treatment of Cardiac Fibrosis Following Myocardial Infarction

Cardiac fibrosis is a common pathological consequence of most myocardial diseases. It is associated with the excessive accumulation of extracellular matrix proteins as well as fibroblast differentiation into myofibroblasts in the cardiac interstitium. This structural remodeling often results in myocardial dysfunctions such as arrhythmias and impaired systolic function in patients with heart conditions, ultimately leading to heart failure and death. An understanding of the precise mechanisms of cardiac fibrosis is still limited due to the numerous signaling pathways, cells, and mediators involved in the process. This review article will focus on the pathophysiological processes associated with the development of cardiac fibrosis. In addition, it will summarize the novel strategies for anti-fibrotic therapies such as epigenetic modifications, miRNAs, and CRISPR technologies as well as various medications in cellular and animal models.

A Therapeutic Perspective of HDAC8 in Different Diseases: An Overview of Selective Inhibitors

Histone deacetylases (HDACs) are epigenetic enzymes which participate in transcriptional repression and chromatin condensation mechanisms by removing the acetyl moiety from acetylated ε-amino group of histone lysines and other non-histone proteins. In recent years, HDAC8, a class I HDAC, has emerged as a promising target for different disorders, including X-linked intellectual disability, fibrotic diseases, cancer, and various neuropathological conditions. Selective HDAC8 targeting is required to limit side effects deriving from the treatment with pan-HDAC inhibitors (HDACis); thus, many endeavours have focused on the development of selective HDAC8is. In addition, polypharmacological approaches have been explored to achieve a synergistic action on multi-factorial diseases or to enhance the drug efficacy. In this frame, proteolysis-targeting chimeras (PROTACs) might be regarded as a dual-targeting approach for attaining HDAC8 proteasomal degradation. This review highlights the most relevant and recent advances relative to HDAC8 validation in various diseases, providing a snapshot of the current selective HDAC8is, with a focus on polyfunctional modulators.

Kasugamycin Is a Novel Chitinase 1 Inhibitor with Strong Antifibrotic Effects on Pulmonary Fibrosis

Pulmonary fibrosis is a devastating lung disease with few therapeutic options. CHIT1 (chitinase 1), an 18 glycosyl hydrolase family member, contributes to the pathogenesis of pulmonary fibrosis through the regulation of TGF-β (transforming growth factor-β) signaling and effector function. Therefore, CHIT1 is a potential therapeutic target for pulmonary fibrosis. This study aimed to identify and characterize a druggable CHIT1 inhibitor with strong antifibrotic activity and minimal toxicity for therapeutic application to pulmonary fibrosis. Extensive screening of small molecule libraries identified the aminoglycoside antibiotic kasugamycin (KSM) as a potent CHIT1 inhibitor. Elevated concentrations of CHIT1 were detected in the lungs of patients with pulmonary fibrosis. In in vivo bleomycin- and TGF-β-stimulated murine models of pulmonary fibrosis, KSM showed impressive antifibrotic effects in both preventive and therapeutic conditions. In vitro studies also demonstrated that KSM inhibits fibrotic macrophage activation, fibroblast proliferation, and myofibroblast transformation. Null mutation of TGFBRAP1 (TGF-β-associated protein 1), a recently identified CHIT1 interacting signaling molecule, phenocopied antifibrotic effects of KSM in in vivo lungs and in vitro fibroblasts responses. KSM inhibits the physical association between CHIT1 and TGFBRAP1, suggesting that the antifibrotic effect of KSM is mediated through regulation of TGFBRAP1, at least in part. These studies demonstrate that KSM is a novel CHIT1 inhibitor with a strong antifibrotic effect that can be further developed as an effective and safe therapeutic drug for pulmonary fibrosis.

Novel mediators of idiopathic pulmonary fibrosis

Fibrosis involving the lung may occur in many settings, including in association with known environmental agents, connective tissue diseases, and exposure to drugs or radiation therapy. The most common form is referred to as 'idiopathic' since a causal agent or specific association has not been determined; the strongest risk factor for idiopathic pulmonary fibrosis is aging. Emerging studies indicate that targeting certain components of aging biology may be effective in mitigating age-associated fibrosis. While transforming growth factor-β1 (TGF-β1) is a central mediator of fibrosis in almost all contexts, and across multiple organs, it is not feasible to target this canonical pathway at the ligand-receptor level due to the pleiotropic nature of its actions; importantly, its homeostatic roles as a tumor-suppressor and immune-modulator make this an imprudent strategy. However, defining targets downstream of its receptor(s) that mediate fibrogenesis, while relatively dispenable for tumor- and immune-suppressive functions may aid in developing safer and more effective therapies. In this review, we explore molecular targets that, although TGF-β1 induced/activated, may be relatively more selective in mediating tissue fibrosis. Additionally, we explore epigenetic mechanisms with global effects on the fibrogenic process, as well as metabolic pathways that regulate aging and fibrosis.

The roles and mechanisms of epigenetic regulation in pathological myocardial remodeling

Pathological myocardial remodeling was still one of the leading causes of death worldwide with an unmet therapeutic need. A growing number of researchers have addressed the role of epigenome changes in cardiovascular diseases, paving the way for the clinical application of novel cardiovascular-related epigenetic targets in the future. In this review, we summarized the emerged advances of epigenetic regulation, including DNA methylation, Histone posttranslational modification, Adenosine disodium triphosphate (ATP)-dependent chromatin remodeling, Non-coding RNA, and RNA modification, in pathological myocardial remodeling. Also, we provided an overview of the mechanisms that potentially involve the participation of these epigenetic regulation.

Specific epigenetic regulators serve as potential therapeutic targets in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF), a disorder observed mostly in older human beings, is characterised by chronic and progressive lung scarring leading to an irreversible decline in lung function. This health condition has a dismal prognosis and the currently available drugs only delay but fail to reverse the progression of lung damage. Consequently, it becomes imperative to discover improved therapeutic compounds and their cellular targets to cure IPF. In this regard, a number of recent studies have targeted the epigenetic regulation by histone deacetylases (HDACs) to develop and categorise antifibrotic drugs for lungs. Therefore, this review focuses on how aberrant expression or activity of Classes I, II and III HDACs alter TGF-β signalling to promote events such as epithelial-mesenchymal transition, differentiation of activated fibroblasts into myofibroblasts, and excess deposition of the extracellular matrix to propel lung fibrosis. Further, this study describes how certain chemical compounds or dietary changes modulate dysregulated HDACs to attenuate five faulty TGF-β-dependent profibrotic processes, both in animal models and cell lines replicating IPF, thereby identifying promising means to treat this lung disorder.

Roles of Epigenetics in Cardiac Fibroblast Activation and Fibrosis

Cardiac fibrosis is a common pathophysiologic process associated with numerous cardiovascular diseases, resulting in cardiac dysfunction. Cardiac fibroblasts (CFs) play an important role in the production of the extracellular matrix and are the essential cell type in a quiescent state in a healthy heart. In response to diverse pathologic stress and environmental stress, resident CFs convert to activated fibroblasts, referred to as myofibroblasts, which produce more extracellular matrix, contributing to cardiac fibrosis. Although multiple molecular mechanisms are implicated in CFs activation and cardiac fibrosis, there is increasing evidence that epigenetic regulation plays a key role in this process. Epigenetics is a rapidly growing field in biology, and provides a modulated link between pathological stimuli and gene expression profiles, ultimately leading to corresponding pathological changes. Epigenetic modifications are mainly composed of three main categories: DNA methylation, histone modifications, and non-coding RNAs. This review focuses on recent advances regarding epigenetic regulation in cardiac fibrosis and highlights the effects of epigenetic modifications on CFs activation. Finally, we provide some perspectives and prospects for the study of epigenetic modifications and cardiac fibrosis.

BAL Transcriptomes Characterize Idiopathic Pulmonary Fibrosis Endotypes With Prognostic Impact

BACKGROUND

Given the plethora of pathophysiologic mechanisms described in idiopathic pulmonary fibrosis (IPF), we hypothesize that the mechanisms driving fibrosis in IPF may be different from one patient to another.

RESEARCH QUESTION

Do IPF endotypes exist and are they associated with outcome?

STUDY DESIGN AND METHODS

Using a publicly available gene expression dataset retrieved from BAL samples of patients with IPF and control participants (GSE70867), we clustered IPF samples based on a dimension reduction algorithm specifically designed for -omics data, called DDR Tree. After clustering, gene set enrichment analysis was performed for functional annotation, associations with clinical variables and prognosis were investigated, and differences in transcriptional regulation were determined using motif enrichment analysis. The findings were validated in three independent publicly available gene expression datasets retrieved from IPF blood samples.

RESULTS

One hundred seventy-six IPF samples from three centers were clustered in six IPF clusters, with distinct functional enrichment. Although clinical characteristics did not differ between the clusters, one cluster conferred worse sex-age-physiology score-corrected survival, whereas another showed a numeric trend toward worse survival (P = .08). The first was enriched for increased epithelial and innate and adaptive immunity signatures, whereas the other showed important telomere and mitochondrial dysfunction, loss of proteostasis, and increased myofibroblast signatures. The existence of these two endotypes, including the impact on survival of the immune endotype, was validated in three independent validation cohorts. Finally, we identified transcription factors regulating the expression of endotype-specific survival-associated genes.

INTERPRETATION

Gene expression-based endotyping in IPF is feasible and can inform clinical evolution. As endotype-specific pathways and survival-associated transcription factors are identified, endotyping may open up the possibility of endotype-tailored therapy.

Proteomic and transcriptomic profiles of human urothelial cancer cells with histone deacetylase 5 overexpression

Urothelial carcinoma (UC) of the urinary bladder is a prevalent cancer worldwide. Because histone deacetylases (HDACs) are important factors in cancer, targeting these epigenetic regulators is considered an attractive strategy to develop novel anticancer drugs. Whereas HDAC1 and HDAC2 promote UC, HDAC5 is often downregulated and only weakly expressed in UC cell lines, suggesting a tumor-suppressive function. We studied the effect of stable lentiviral-mediated HDAC5 overexpression in four UC cell lines with different phenotypes (RT112, VM-Cub-1, SW1710, and UM-UC-3, each with vector controls). In particular, comprehensive proteomics and RNA-seq transcriptomics analyses were performed on the four cell line pairs, which are described here. For comparison, the immortalized benign urothelial cell line HBLAK was included. These datasets will be a useful resource for researchers studying UC, and especially the influence of HDAC5 on epithelial-mesenchymal transition (EMT). Moreover, these data will inform studies on HDAC5 as a less studied member of the HDAC family in other cell types and diseases, especially fibrosis.

Resistance to Gemcitabine in Pancreatic Ductal Adenocarcinoma: A Physiopathologic and Pharmacologic Review

Pancreatic ductal adenocarcinoma (PDAC) is a very aggressive tumor with a poor prognosis and inadequate response to treatment. Many factors contribute to this therapeutic failure: lack of symptoms until the tumor reaches an advanced stage, leading to late diagnosis; early lymphatic and hematic spread; advanced age of patients; important development of a pro-tumoral and hyperfibrotic stroma; high genetic and metabolic heterogeneity; poor vascular supply; a highly acidic matrix; extreme hypoxia; and early development of resistance to the available therapeutic options. In most cases, the disease is silent for a long time, andwhen it does become symptomatic, it is too late for ablative surgery; this is one of the major reasons explaining the short survival associated with the disease. Even when surgery is possible, relapsesare frequent, andthe causes of this devastating picture are the low efficacy ofand early resistance to all known chemotherapeutic treatments. Thus, it is imperative to analyze the roots of this resistance in order to improve the benefits of therapy. PDAC chemoresistance is the final product of different, but to some extent, interconnected factors. Surgery, being the most adequate treatment for pancreatic cancer and the only one that in a few selected cases can achieve longer survival, is only possible in less than 20% of patients. Thus, the treatment burden relies on chemotherapy in mostcases. While the FOLFIRINOX scheme has a slightly longer overall survival, it also produces many more adverse eventsso that gemcitabine is still considered the first choice for treatment, especially in combination with other compounds/agents. This review discusses the multiple causes of gemcitabine resistance in PDAC.

Romidepsin (FK228) improves the survival of allogeneic skin grafts through downregulating the production of donor-specific antibody via suppressing the IRE1α-XBP1 pathway

Antibody-mediated rejection (AMR) is one of the major causes of graft loss after transplantation. Recently, the regulation of B cell differentiation and the prevention of donor-specific antibody (DSA) production have gained increased attention in transplant research. Herein, we established a secondary allogeneic in vivo skin transplant model to study the effects of romidepsin (FK228) on DSA. The survival of grafted skins was monitored daily. The serum levels of DSA and the number of relevant immunocytes in the recipient spleens were evaluated by flow cytometry. Then, we isolated and purified B cells from B6 mouse spleens in vitro by magnetic bead sorting. The B cells were cultured with interleukin-4 (IL-4) and anti-clusters of differentiation 40 (CD40) antibody with or without FK228 treatment. The immunoglobulin G1 (IgG1) and IgM levels in the supernatant were evaluated by enzyme-linked immunosorbent assay (ELISA). Quantitative reverse transcription-polymerase chain reaction (RT-qPCR) and western blotting were conducted to determine the corresponding levels of messenger RNA (mRNA) and protein expression in cultured cells and the recipient spleens. The results showed that FK228 significantly improved the survival of allogeneic skin grafts. Moreover, FK228 inhibited DSA production in the serum along with the suppression of histone deacetylase 1 (HADC1) and HDAC2 and the upregulation of the acetylation of histones H2A and H3. It also inhibited the differentiation of B cells to plasma cells, decreased the transcription of positive regulatory domain-containing 1 (Prdm1) and X-box-binding protein 1 (Xbp1), and decreased the expression of phosphorylated inositol-requiring enzyme 1 α (p-IRE1α), XBP1, and B lymphocyte-induced maturation protein-1 (Blimp-1). In conclusion, FK228 could decrease the production of antibodies by B cells via inhibition of the IRE1α-XBP1 signaling pathway. Thus, FK228 is considered as a promising therapeutic agent for the clinical treatment of AMR.

Epigenetic remodeling in heart failure with preserved ejection fraction

PURPOSE OF REVIEW

In this review, we critically address the role of epigenetic processing and its therapeutic modulation in heart failure with preserved ejection fraction (HFpEF).

RECENT FINDINGS

HFpEF associates with a poor prognosis and the identification of novel molecular targets and therapeutic approaches are in high demand. Emerging evidence indicates a key involvement of epigenetic signals in the regulation of transcriptional programs underpinning features of HFpEF. The growing understanding of chromatin dynamics has led to the development of selective epigenetic drugs able to reset transcriptional changes thus delaying or preventing the progression toward HFpEF. Epigenetic information in the setting of HFpEF can be employed to: (i) dissect novel epigenetic networks and chromatin marks contributing to HFpEF; (ii) unveil circulating and cell-specific epigenetic biomarkers; (iii) build predictive models by using computational epigenetics and deep machine learning; (iv) develop new chromatin modifying drugs for personalized management of HFpEF.

SUMMARY

Acquired epigenetic signatures during the lifetime can contribute to derail molecular pathways involved in HFpEF. A scrutiny investigation of the individual epigenetic landscape will offer opportunities to develop personalized epigenetic biomarkers and therapies to fight HFpEF in the decades to come.

Epithelial-mesenchymal transition in organ fibrosis development: current understanding and treatment strategies

Organ fibrosis is a process in which cellular homeostasis is disrupted and extracellular matrix is excessively deposited. Fibrosis can lead to vital organ failure and there are no effective treatments yet. Although epithelial–mesenchymal transition (EMT) may be one of the key cellular mechanisms, the underlying mechanisms of fibrosis remain largely unknown. EMT is a cell phenotypic process in which epithelial cells lose their cell-to-cell adhesion and polarization, after which they acquire mesenchymal features such as infiltration and migration ability. Upon injurious stimulation in different organs, EMT can be triggered by multiple signaling pathways and is also regulated by epigenetic mechanisms. This narrative review summarizes the current understanding of the underlying mechanisms of EMT in fibrogenesis and discusses potential strategies for attenuating EMT to prevent and/or inhibit fibrosis. Despite better understanding the role of EMT in fibrosis development, targeting EMT and beyond in developing therapeutics to tackle fibrosis is challenging but likely feasible.

Focusing on Mechanoregulation Axis in Fibrosis: Sensing, Transduction and Effecting

Fibrosis, a pathologic process featured by the excessive deposition of connective tissue components, can affect virtually every organ and has no satisfactory therapy yet. Fibrotic diseases are often associated with organ dysfunction which leads to high morbidity and mortality. Biomechanical stmuli and the corresponding cellular response havebeen identified in fibrogenesis, as the fibrotic remodeling could be seen as the incapacity to reestablish mechanical homeostasis: along with extracellular matrix accumulating, the physical property became more “stiff” and could in turn induce fibrosis. In this review, we provide a comprehensive overview of mechanoregulation in fibrosis, from initialing cellular mechanosensing to intracellular mechanotransduction and processing, and ends up in mechanoeffecting. Our contents are not limited to the cellular mechanism, but further expand to the disorders involved and current clinical trials, providing an insight into the disease and hopefully inspiring new approaches for the treatment of tissue fibrosis.

Tubastatin A suppresses the proliferation of fibroblasts in epidural fibrosis through phosphatidylinositol-3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) signalling pathway

OBJECTIVES

This study was designed to explore the effect of tubastatin A (Tub A) on epidural fibrosis and the underlying mechanism.

METHODS

Histone deacetylase 6 (HDAC6)-overexpressed fibroblasts were constructed, and the effect of Tub A on the proliferation of activated fibroblasts was detected by Cell Counting Kit-8, 5-ethynyl-2'-deoxyuridine (EdU) and cell cycle assay. Besides, 20 Sprague-Dawley rats were subjected to animal laminectomy model construction and then randomly treated with 4% dimethyl sulfoxide (DMSO) (diluted in 0.9% saline) or Tub A (10 mg/kg/day), separately. The expression of HDAC6 and phosphatidylinositol-3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway-related proteins was measured in epidural fibrosis tissues.

KEY FINDINGS

HDAC6 was overexpressed in activated fibroblasts and epidural scar tissues of rat models. Cell proliferation was remarkably elevated in HDAC6-overexpressed fibroblasts, which was reflected by cell viability, EdU and flow cytometry-based cell cycle assay, and paralleled with the increased expression of phosphorylated PI3K, AKT and mTOR, which was remarkably reversed following Tub A treatment. 740Y-P activator addition significantly reversed the declined fibroblast proliferation induced by Tub A. The expressions of PI3K/AKT/mTOR pathway-related proteins were also reduced in epidural tissues in rat models with Tub A treatment.

CONCLUSION

Tub A could prevent epidural fibrosis formation by inhibiting fibroblast proliferation through mediating PI3K/AKT/mTOR pathway.

Cardiac Complications: The Understudied Aspect of Cancer Cachexia

The global burden of cancer cachexia is increasing along with drastic increase in cancer patients. Cancer itself leads to cachexia, and cachexia development is associated with events like altered hemodynamics, and reduced functional capacity of the heart among others which lead to failure of the heart and are called cardiovascular complications associated with cancer cachexia. In some patients, the anti-cancer therapy also leads to this cardiovascular complications. So, in this review, an attempt is made to understand the mechanisms, pathophysiology of cardiovascular events in cachectic patients. Important processes which cause cardiovascular complications include alterations in the structure of the heart, loss of cardiac mass and functioning, cardiac fibrosis and cardiac remodeling, apoptosis, cardiac muscle atrophy, and mitochondrial alterations. Previously, the available treatment options were limited to nutraceuticals and physical exercise. Recently, studies with some prospective agents that can improve cardiac health have been reported, but whether their action is effective in cardiovascular complications associated with cancer cachexia is not known or are under trial.

Chasing a Breath of Fresh Air in Cystic Fibrosis (CF): Therapeutic Potential of Selective HDAC6 Inhibitors to Tackle Multiple Pathways in CF Pathophysiology

Compelling new support has been provided for histone deacetylase isoform 6 (HDAC6) as a common thread in the generation of the dysregulated proinflammatory and fibrotic phenotype in cystic fibrosis (CF). HDAC6 also plays a crucial role in bacterial clearance or killing as a direct consequence of its effects on CF immune responses. Inhibiting HDAC6 functions thus eventually represents an innovative and effective strategy to tackle multiple aspects of CF-associated lung disease. In this Perspective, we not only showcase the latest evidence linking HDAC(6) activity and expression with CF phenotype but also track the new dawn of HDAC(6) modulators in CF and explore potentialities and future perspectives in the field.

Inflammation, Fibrosis and Cancer: Mechanisms, Therapeutic Options and Challenges

Uncontrolled inflammation is a salient factor in multiple chronic inflammatory diseases and cancers. In this review, we provided an in-depth analysis of the relationships and distinctions between uncontrolled inflammation, fibrosis and cancers, while emphasizing the challenges and opportunities of developing novel therapies for the treatment and/or management of these diseases. We described how drug delivery systems, combination therapy and the integration of tissue-targeted and/or pathways selective strategies could overcome the challenges of current agents for managing and/or treating chronic inflammatory diseases and cancers. We also recognized the value of the re-evaluation of the disease-specific roles of multiple pathways implicated in the pathophysiology of chronic inflammatory diseases and cancers-as well as the application of data from single-cell RNA sequencing in the success of future drug discovery endeavors.

Modulation of H4K16Ac levels reduces pro-fibrotic gene expression and mitigates lung fibrosis in aged mice

Histone H4 lysine16 acetylation (H4K16Ac) modulates chromatin structure by serving as a switch from a repressive to a transcriptionally active state. This euchromatin mark is associated with active transcription. In this study, we investigated the effects of H4K16Ac on the expression of pro-fibrotic genes in lung fibroblasts from patients with idiopathic pulmonary fibrosis (IPF) and in an aging murine model of lung fibrosis. Methods: The lung tissues and fibroblasts from human IPF/non-IPF donors and from aged mice with/without bleomycin induced lung fibrosis were used in this study. The H4K16Ac levels were examined by immunohistochemistry or western blots. RNA silencing of H4K16Ac acetyltransferase Mof was used to reduce H4K16Ac levels in IPF fibroblasts. The effects of reduced H4K16Ac on pro-fibrotic gene expression were examined by western blots and real-time PCR. The association of H4K16Ac with these genes' promoter region were evaluated by ChIP assays. The gene expression profile in siRNA Mof transfected IPF cells were determined by RNA-Seq. The impact of H4K16Ac levels on lung fibrosis was evaluated in an aging murine model. Results: Aged mice with bleomycin induced lung fibrosis showed increased H4K16Ac levels. Human lung fibroblasts with siRNA Mof silencing demonstrated reduced H4K16Ac, and significantly down-regulated profibrotic genes, such as α-smooth muscle actin (α-SMA), collagen I, Nox4, and survivin. ChIP assays confirmed the associations of these pro-fibrotic genes' promoter region with H4K16Ac, while in siRNA Mof transfected cells the promoter/H4K16Ac associations were depleted. RNA-seq data demonstrated that Mof knockdown altered gene expression and cellular pathways, including cell damage and repair. In the aging mice model of persistent lung fibrosis, 18-month old mice given intra-nasal siRNA Mof from week 3 to 6 following bleomycin injury showed improved lung architecture, decreased total hydroxyproline content and lower levels of H4K16Ac. Conclusions: These results indicate a critical epigenetic regulatory role for histone H4K16Ac in the pathogenesis of pulmonary fibrosis, which will aid in the development of novel therapeutic strategies for age-related diseases such as IPF.

Nuclear mechanosensing drives chromatin remodelling in persistently activated fibroblasts

Fibrotic disease is caused by the continuous deposition of extracellular matrix by persistently activated fibroblasts (also known as myofibroblasts), even after the resolution of the injury. Using fibroblasts from porcine aortic valves cultured on hydrogels that can be softened via exposure to ultraviolet light, here we show that increased extracellular stiffness activates the fibroblasts, and that cumulative tension on the nuclear membrane and increases in the activity of histone deacetylases transform transiently activated fibroblasts into myofibroblasts displaying condensed chromatin with genome-wide alterations. The condensed structure of the myofibroblasts is associated with cytoskeletal stability, as indicated by the inhibition of chromatin condensation and myofibroblast persistence after detachment of the nucleus from the cytoskeleton via the displacement of endogenous nesprins from the nuclear envelope. We also show that the chromatin structure of myofibroblasts from patients with aortic valve stenosis is more condensed than that of myofibroblasts from healthy donors. Our findings suggest that nuclear mechanosensing drives distinct chromatin signatures in persistently activated fibroblasts.

Selective Inhibitors of Histone Deacetylase 10 (HDAC-10)

Histone acetylation balance is one epigenetic mechanism controlling gene expression associated with disease progression. It has been observed that histone deacetylase 10 (HDAC-10) isozyme contributes to the chemotherapy resistance; in addition, the poor clinical outcome observed in patients with aggressive solid tumors, such as neuroblastoma, has been associated with its overexpression. Moreover, HDAC-10 selective inhibition suppresses the autophagic response, thus providing an improved risk-benefit profile compared to cytotoxic cancer chemotherapy drugs. On these bases, HDAC-10 is becoming an emerging target for drug design. Due to the rapid progress in the development of next-generation HDAC inhibitors, this review article aims to provide an overview on novel selective or dual HDAC-8/10 inhibitors, as new leads for cancer chemotherapy, able to avoid the severe side-effects of several actual approved "pan" HDAC inhibitors. A literature search was conducted in MedLine, PubMed, Caplus, SciFinder Scholar databases from 2015 to the present. Since the disclosure that the HDAC-6 inhibitor Tubastatin A was able to bind HDAC-10 efficiently, several related analogues were synthesized and tested. Both tricyclic (25-30) and bicyclic (31-42) derivatives were considered. The best pharmacological profile was shown by 36 (HDAC-10 pIC₅₀ = 8.4 and pIC₅₀ towards Class I HDACs from 5.2-6.4). In parallel, based on the evidence that high levels of HDAC-8 are a marker of poor prognosis in neuroblastoma treatment, dual HDAC-8/10 inhibitors were designed. The hydroxamic acid TH34 (HDAC-8 and 10 IC₅₀ = 1.9 µM and 7.7 µM, respectively) and the hybrid derivatives 46d, 46e and 46g were the most promising both in terms of potency and selectivity. Literature surveys indicate several structural requirements for inhibitory potency and selectivity towards HDAC-10, e.g., electrostatic and/or hydrogen bond interactions with E274 and complementarity to the P(E,A) CE motif helix.

Pan-Cancer Analysis of Genomic and Prognostic Characteristics Associated With Coronavirus Disease 2019 Regulators

Background: Cancer patients are alleged to have poor coronavirus disease 2019 (COVID-19) outcomes. However, no systematic or comprehensive analyses of the role and mechanisms of COVID-19 receptor-related regulators in cancer are available.

Methods: We comprehensively evaluated the genomic alterations and their clinical relevance of six COVID-19 receptor-related regulators [transmembrane serine protease 2 (TMPRSS2), angiotensinogen (AGT), angiotensin-converting enzyme 1 (ACE1), solute carrier family 6 member 19 (SLC6A19), angiotensin-converting enzyme 2 (ACE2), and angiotensin II receptor type 2 (AGTR2)] across a broad spectrum of solid tumors. RNA-seq data, single nucleotide variation data, copy number variation data, methylation data, and miRNA–mRNA interaction network data from The Cancer Genome Atlas (TCGA) of 33 solid tumors were analyzed. We assessed the sensitivities of drugs targeting COVID-19 receptor-related regulators, using information from the Cancer Therapeutics Response Portal database.

Results: We found that there are widespread genetic alterations of COVID-19 regulators and that their expression levels were significantly correlated with the activity of cancer hallmark-related pathways. Moreover, COVID-19 receptor-related regulators may be used as prognostic biomarkers. By mining the genomics of drug sensitivities in cancer databases, we discovered a number of potential drugs that may target COVID-19 receptor-related regulators.

Conclusion: This study revealed the genomic alterations and clinical characteristics of COVID-19 receptor-related regulators across 33 cancers, which may clarify the potential mechanism between COVID-19 receptor-related regulators and tumorigenesis and provide a novel approach for cancer treatments.

Backstage players of fibrosis: NOX4, mTOR, HDAC, and S1P; companions of TGF-β

The fibrotic process could be easily defined as a pathological excess of extracellular matrix deposition, leading to disruption of tissue architecture and eventually loss of function; however, this process involves a complex network of several signal transduction pathways. Virtually almost all organs could be affected by fibrosis, the most affected are the liver, lung, skin, kidney, heart, and eyes; in all of them, the transforming growth factor-beta (TGF-β) has a central role. The canonical and non-canonical signal pathways of TGF-β impact the fibrotic process at the cellular and molecular levels, inducing the epithelial-mesenchymal transition (EMT) and the induction of profibrotic gene expression with the consequent increase in proteins such as alpha-smooth actin (α-SMA), fibronectin, collagen, and other extracellular matrix proteins. Recently, it has been reported that some molecules that have not been typically associated with the fibrotic process, such as nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 4 (NOX4), mammalian target of rapamycin (mTOR), histone deacetylases (HDAC), and sphingosine-1 phosphate (S1P); are critical in its development. In this review, we describe and discuss the role of these new players of fibrosis and the convergence with TGF-β signaling pathways, unveiling new insights into the panorama of fibrosis that could be useful for future therapeutic targets.

Improved HDAC Inhibition, Stronger Cytotoxic Effect and Higher Selectivity against Leukemias and Lymphomas of Novel, Tricyclic Vorinostat Analogues

Histone deacetylase (HDAC) inhibitors are a class of drugs used in the cancer treatment. Here, we developed a library of 19 analogues of Vorinostat, an HDAC inhibitor used in lymphomas treatment. In Vorinostat, we replaced the hydrophobic phenyl group with various tricyclic 'caps' possessing a central, eight-membered, heterocyclic ring, and investigated the HDAC activity and cytotoxic effect on the cancer and normal cell lines. We found that 3 out of the 19 compounds, based on dibenzo[b,f]azocin-6(5H)-one, 11,12-dihydrodibenzo[b,f]azocin-6(5H)-one, and benzo[b]naphtho[2,3-f][1,5]diazocine-6,14(5H,13H)-dione scaffolds, showed better HDACs inhibition than the referenced Vorinostat. In leukemic cell line MV4-11 and in the lymphoma cell line Daudi, three compounds showed lower IC50 values than Vorinostat. These compounds had higher activity and selectivity against MV4-11 and Daudi cell lines than reference Vorinostat. We also observed a strong correlation between HDACs inhibition and the cytotoxic effect. Cell lines derived from solid tumours: A549 (lung carcinoma) and MCF-7 (breast adenocarcinoma) as well as reference BALB/3T3 (normal murine fibroblasts) were less susceptible to compounds tested. Developed derivatives show improved properties than Vorinostat, thus they could be considered as possible agents for leukemia and lymphoma treatment.

Discovery of a novel HDACi structure that inhibits the proliferation of ovarian cancer cells in vivo and in vitro

Histone deacetylases (HDACs) exhibit increased expression in cancer and promote oncogenesis via the acetylation of or interactions with key transcriptional regulators. HDAC inhibitors (HDACis) decrease HDAC activity to selectively inhibit the occurrence and development of tumors. Our study screened and obtained a new HDACi structure. In vitro experiments have showed that among the leads, Z31216525 significantly inhibited the proliferation and induced the apoptosis of epithelial ovarian cancer (EOC) cells. In vivo experiments demonstrated that compared to the control, Z31216525 significantly inhibited tumor growth and showed very low toxicity. Further mechanistic studies revealed that Z31216525 may exert an antitumor effect by inhibiting the expression of the c-Myc gene. Collectively, our studies identified a novel HDACi that is expected to become a new potential therapeutic drug for EOC and has important value for the design of new HDACi structures.

Harnessing the Role of HDAC6 in Idiopathic Pulmonary Fibrosis: Design, Synthesis, Structural Analysis, and Biological Evaluation of Potent Inhibitors

Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease characterized by a progressive-fibrosing phenotype. IPF has been associated with aberrant HDAC activities confirmed by our immunohistochemistry studies on HDAC6 overexpression in IPF lung tissues. We herein developed a series of novel hHDAC6 inhibitors, having low inhibitory potency over hHDAC1 and hHDAC8, as potential pharmacological tools for IPF treatment. Their inhibitory potency was combined with low in vitro and in vivo toxicity. Structural analysis of 6h and structure-activity relationship studies contributed to the optimization of the binding mode of the new molecules. The best-performing analogues were tested for their efficacy in inhibiting fibrotic sphere formation and cell viability, proving their capability in reverting the IPF phenotype. The efficacy of analogue 6h was also determined in a validated human lung model of TGF-β1-dependent fibrogenesis. The results highlighted in this manuscript may pave the way for the identification of first-in-class molecules for the treatment of IPF.

Dissecting Histone Deacetylase 3 in Multiple Disease Conditions: Selective Inhibition as a Promising Therapeutic Strategy

The acetylation of histone and non-histone proteins has been implicated in several disease states. Modulation of such epigenetic modifications has therefore made histone deacetylases (HDACs) important drug targets. HDAC3, among various class I HDACs, has been signified as a potentially validated target in multiple diseases, namely, cancer, neurodegenerative diseases, diabetes, obesity, cardiovascular disorders, autoimmune diseases, inflammatory diseases, parasitic infections, and HIV. However, only a handful of HDAC3-selective inhibitors have been reported in spite of continuous efforts in design and development of HDAC3-selective inhibitors. In this Perspective, the roles of HDAC3 in various diseases as well as numerous potent and HDAC3-selective inhibitors have been discussed in detail. It will surely open up a new vista in the discovery of newer, more effective, and more selective HDAC3 inhibitors.

HDAC Inhibitor Abrogates LTA-Induced PAI-1 Expression in Pleural Mesothelial Cells and Attenuates Experimental Pleural Fibrosis

Lipoteichoic acid (LTA) stimulates pleural mesothelial cell (PMC) to overproduce plasminogen activator inhibitor-1 (PAI-1), and thus may promote pleural fibrosis in Gram-positive bacteria (GPB) parapneumonic effusion (PPE). Histone deacetylase inhibitor (HDACi) was found to possess anti-fibrotic properties. However, the effects of HDACi on pleural fibrosis remain unclear. The effusion PAI-1 was measured among 64 patients with GPB PPE. Pleural fibrosis was measured as radiographical residual pleural thickening (RPT) and opacity at a 12-month follow-up. The LTA-stimulated human PMCs and intrapleural doxycycline-injected rats were pretreated with or without the pan-HDACi, m-carboxycinnamic acid bis-hydroxamide (CBHA), then PAI-1 and collagen expression and activated signalings in PMCs, and morphologic pleural changes in rats were measured. Effusion PAI-1 levels were significantly higher in GPB PPE patients with RPT > 10 mm (n = 26) than those without (n = 38), and had positive correlation with pleural fibrosis shadowing. CBHA significantly reduced LTA-induced PAI-1 and collagen expression via inhibition of JNK, and decreased PAI-1 promoter activity and mRNA levels in PMCs. Furthermore, in doxycycline-treated rats, CBHA substantially repressed PAI-1 and collagen synthesis in pleural mesothelium and minimized pleural fibrosis. Conclusively, CBHA abrogates LTA-induced PAI-1 and collagen expression in PMCs and attenuates experimental pleural fibrosis. PAI-1 inhibition by HDACi may confer potential therapy for pleural fibrosis.

HDAC11: a multifaceted histone deacetylase with proficient fatty deacylase activity and its roles in physiological processes

The histone deacetylases (HDACs) family of enzymes possess deacylase activity for histone and nonhistone proteins; HDAC11 is the latest discovered HDAC and the only member of class IV. Besides its shared HDAC family catalytical activity, recent studies underline HDAC11 as a multifaceted enzyme with a very efficient long-chain fatty acid deacylase activity, which has open a whole new field of action for this protein. Here, we summarize the importance of HDAC11 in a vast array of cellular pathways, which has been recently highlighted by discoveries about its subcellular localization, biochemical features, and its regulation by microRNAs and long noncoding RNAs, as well as its new targets and interactors. Additionally, we discuss the recent work showing the consequences of HDAC11 dysregulation in brain, skeletal muscle, and adipose tissue, and during regeneration in response to kidney, skeletal muscle, and vascular injuries, underscoring HDAC11 as an emerging hub protein with physiological functions that are much more extensive than previously thought, and with important implications in human diseases.

The Role of Macrophages in the Development of Acute and Chronic Inflammatory Lung Diseases

Macrophages play an important role in the innate and adaptive immune responses of organ systems, including the lungs, to particles and pathogens. Cumulative results show that macrophages contribute to the development and progression of acute or chronic inflammatory responses through the secretion of inflammatory cytokines/chemokines and the activation of transcription factors in the pathogenesis of inflammatory lung diseases, such as acute lung injury (ALI), acute respiratory distress syndrome (ARDS), ARDS related to COVID-19 (coronavirus disease 2019, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)), allergic asthma, chronic obstructive pulmonary disease (COPD), and idiopathic pulmonary fibrosis (IPF). This review summarizes the functions of macrophages and their associated underlying mechanisms in the development of ALI, ARDS, COVID-19-related ARDS, allergic asthma, COPD, and IPF and briefly introduces the acute and chronic experimental animal models. Thus, this review suggests an effective therapeutic approach that focuses on the regulation of macrophage function in the context of inflammatory lung diseases.