Tubastatin ameliorates pulmonary fibrosis by targeting the TGFβ-PI3K-Akt pathway

Nobiletin from Citrus reticulata Blanco alleviates pulmonary fibrosis through inhibiting the PI3K/AKT pathway and epithelial-mesenchymal transition

ETHNOPHARMACOLOGICAL RELEVANCE

Citrus reticulata Blanco, a traditional Chinese herb, has been utilized for bronchitis-related conditions. Nobiletin (NOB), the primary bioactive compound in Citrus reticulata Blanco, exhibits anti-inflammatory, antioxidant, and antifibrotic properties. However, the efficacy of NOB in pulmonary fibrosis (PF) and the underlying mechanisms remain ambiguous.

AIM OF THE STUDY

This study is aimed to assess the effectiveness of NOB in the management of pulmonary fibrosis and to delineate the fundamental molecular mechanisms responsible for its action.

MATERIALS AND METHODS

Bleomycin (BLM)-induced PF in C57BL/6 mice and transforming growth factor-β1 (TGF-β1)-induced molecular alterations in NIH3T3 and A549 cells, a number of techniques were used to study the efficacy and mechanism of NOB in PF, including Sirius Red collagen assays, Western blot (WB), immunofluorescence (IF), Micro-CT Imaging, pulmonary function assay, histopathological examination, proteomic analysis, wound healing, transwell, and immunocytochemistry (IHC) were utilized to analyze the efficacy and mechanism of NOB in PF.

RESULTS

Our study demonstrated that NOB exhibited antifibrotic effects in TGF-β1-induced NIH3T3 cells, which was further corroborated in BLM-induced C57BL/6 mice. Utilizing proteomics analysis, we determined that the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) signaling cascade and cellular adhesion processes were of significant importance. When A549 cells were induced with TGF-β1, our observations revealed that NOB could inhibit epithelial-mesenchymal transition (EMT) and display antifibrotic effects by modulating the PI3K/AKT pathway.

CONCLUSIONS

NOB could alleviate PF through inhibiting the PI3K/AKT pathway and EMT, suggesting it as a beneficial adjunct therapy for PF patients.

Epigenetic targets and their inhibitors in the treatment of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a deadly lung disease characterized by fibroblast proliferation, excessive extracellular matrix buildup, inflammation, and tissue damage, resulting in respiratory failure and death. Recent studies suggest that impaired interactions among epithelial, mesenchymal, immune, and endothelial cells play a key role in IPF development. Advances in bioinformatics have also linked epigenetics, which bridges gene expression and environmental factors, to IPF. Despite the incomplete understanding of the pathogenic mechanisms underlying IPF, recent preclinical studies have identified several novel epigenetic therapeutic targets, including DNMT, EZH2, G9a/GLP, PRMT1/7, KDM6B, HDAC, CBP/p300, BRD4, METTL3, FTO, and ALKBH5, along with potential small-molecule inhibitors relevant for its treatment. This review explores the pathogenesis of IPF, emphasizing epigenetic therapeutic targets and potential small molecule drugs. It also analyzes the structure-activity relationships of these epigenetic drugs and summarizes their biological activities. The objective is to advance the development of innovative epigenetic therapies for IPF.

Identification of potential mechanisms of Schisandrin B in the treatment of idiopathic pulmonary fibrosis by integrating network pharmacology and experimental validation

Idiopathic pulmonary fibrosis (IPF) is a worsening fibrotic condition characterized by a short survival rate and limited treatment options. This study evaluates the potential anti-fibrotic properties of Schisandrin B (Sch B) through network pharmacology and experimental validation. A mouse model of bleomycin-induced pulmonary fibrosis was established, and the modeled mice were treated with Sch B at three doses (20 mg/kg/day, 40 mg/kg/day, and 80 mg/kg/day). A fibrotic model was developed in NIH/3T3 cells by treating them with TGF-β (10 ng/mL) and administering Sch B at various concentrations (10, 20, and 40 µM). The results revealed that Sch B treatment delayed the development of bleomycin-induced pulmonary fibrosis and substantially decreased the transcription levels of collagen I and α-SMA in TGF-β-induced fibroblasts. Core targets were screened with protein-protein interaction network analysis, molecular complex detection (MCODE), and CytoHubba plugin. The application of Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, and molecular docking highlighted the significance of the HIF-1α signaling pathway in the potential mechanism of Sch B in IPF therapy. Western blot, PCR, and immunofluorescence were performed to validate the effects of Sch B on HIF-1α. In vivo and in vitro, Sch B administration reduced HIF-1α expression. These outcomes provide valuable insights into the potential mechanism by which Sch B delays IPF development, with HIF-1α potentially serving as a key target. However, further investigation is warranted to assess the safety and efficacy of Sch B in clinical settings.

Hepatic microtubule destabilization facilitates liver fibrosis in the mouse model of Wilson disease

Wilson disease (WD) is a potentially fatal metabolic disorder caused by the inactivation of the copper (Cu) transporter ATP7B, resulting in systemic Cu overload and fibroinflammatory liver disease. The molecular mechanism and effects of elevated Cu on cytoskeletal dynamics in liver fibrogenesis are not clear. Here, we tested the regulation of hepatic cytoskeleton and fibrogenesis with respect to Cu overload in WD. Atp7b-/- (knockout) mice with established liver disease, hepatocyte-specific Atp7b△Hep knockout mice without fibroinflammatory disease, and the age-and sex-matched controls were compared using Western blotting, real-time quantitative reverse transcription PCR (qRT-PCR), immunohistochemical (IHC) staining and transcriptomics (RNA-sequencing) analysis. In Atp7b-/- mice with developed liver disease, there is a significant increase in cytoskeletal protein expression with a reduction in α-tubulin acetylation. In these mice before the onset of liver pathology, no significant changes in cytoskeletal nor hepatic stellate cell activation are observed. As hepatic copper levels rise, an increase in cytoskeletal proteins with a decrease in acetylated-α-tubulin/α-tubulin ratio occurs. RNA-sequencing, qRT-PCR, and immunostaining confirm that the tubulin is upregulated at the transcriptional level and hepatocytes are the primary source of early tubulin increases before fibrosis. An increase in α-tubulin with a decrease in α-tubulin acetylation via Hdac6 and Sirt2 induction facilitates fibrosis as reflected by concomitant increases in desmin and α-SMA immunostaining in Atp7b-/- mice at 20 weeks. Moreover, strongly positive correlations between α-tubulin and α-tubulin deacetylase with the expression of liver fibrosis markers are observed in animal and human WD. Hepatocyte-specific Atp7b△Hep mice lack significant changes in tubulin as well as fibrosis despite hepatic steatosis. This study provides evidence that microtubule destabilization causes cytoskeletal rearrangement and facilitates hepatic stellate cell (HSC) activation and fibrosis in the murine model of WD. KEY MESSAGES: Hepatic cytoskeleton system is induced in Wilson disease. Hepatic microtubules acetylation is dysregulated in murine Wilson disease. Microtubules destabilization is positively associated with liver fibrosis in Wilson disease. Microtubules destabilization concomitant with fibrogenesis exacerbates WD progression.

Pentadecanoic acid attenuates thioacetamide-induced liver fibrosis by modulating oxidative stress, inflammation, and ferroptosis pathways in rat

Pentadecanoic acid (PDA) has been reported as a histone deacetylase 6 inhibitor. Numerous studies have shown that Histone deacetylases (HDACs) are significantly involved in the development of fibrosis. The present study focused on assessing the anti-fibrotic properties of PDA in ameliorating hepatic fibrosis induced by thioacetamide (TAA) in Wistar rats. PDA was administered orally at the doses of 10, 20 and 40 mg/kg daily, whereas TAA was administered intraperitoneally at a dose of 200 mg/kg twice weekly, for a period of 9 weeks. Administration of TAA significantly increased the relative and absolute liver weight, alanine transaminase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), gamma glutamyl transferase (γ-GT), myeloperoxidase (MPO), malondialdehyde (MDA) and reduced the glutathione (GSH) levels and PDA intervention restored the same. PDA treatment ameliorated TAA-induced collagen deposition and infiltration of inflammatory cells as revealed by Sirius red and H&E staining. Additionally, histopathological analysis revealed lymphocyte infiltration, collagen build up, development of bridging fibrosis, degeneration of the portal triad, iron accumulation, and necrosis in TAA-treated rats. The intervention with PDA significantly mitigated these pathological changes. PDA treatment significantly downregulated the expressions of TGF-β1, α-SMA, NLRP3, NF-κB and HDAC6 against TAA-induced liver damage. The present study clearly demonstrated that PDA treatment significantly alleviated TAA-induced hepatic fibrosis by ameliorating the inflammatory markers.

Discussion of the material basis for prevention and treatment of pulmonary fibrosis using naturally medicinal and edible homologous herbs based on the dynamic process of Nrf2, NF-κB and TGF-β in PF

Pulmonary fibrosis (PF) is a progressive chronic lung disease with a high incidence and poor prognosis. Despite extensive research into the mechanisms that initiate and drive the progression of pulmonary fibrosis, developing effective treatments remains challenging due to the multiple etiologies, pathogenic links, and signaling pathways involved in PF. Indeed, nuclear factor erythroid 2-related factor 2 (Nrf2), nuclear factor kappa-B (NF-κB), and transforming growth factor-beta (TGF-β) are central players in the pathogenesis of pulmonary fibrosis, and each of these factors influences distinct yet interconnected processes that collectively contribute to disease progression: Nrf2 upregulates antioxidants to mitigate oxidative stress, NF-κB modulates inflammatory responses, and TGF-β promotes fibroblast activation and extracellular matrix (ECM) deposition, leading to fibrosis. Targeting these pathways may offer therapeutic strategies, uncover new insights and provide potential therapeutic targets for PF. Absolutely, the interactions between Nrf2, NF-κB, and TGF-β pathways are complex and can significantly influence the progression of PF, which indicated that targeting a single pathway may show poor efficacy in managing the condition. Moreover, few therapies that effectively intervene in these pathways have been approved. This review focused on the molecular mechanisms of Nrf2, NF-κB, and TGF-β involving in PF and the material basis of the naturally medicinal and edible homologous herbs, which provides a solid foundation for understanding the disease's pathogenesis, and supports the development of therapeutic drugs or treatments for addressing the complex nature of PF.

HDAC6 deficiency aggravates ductular reactions through aggresome-mediated hepatocyte apoptosis

Ductular reactions (DRs) contribute significantly to the occurrence and development of liver disease. While histone deacetylase 6 (HDAC6) is known to regulate injury repair in multiple tissues, its exact role in DRs remains unclear. This study examined the role and underlying mechanism of HDAC6 in DRs using an HDAC6 knockout (HDAC6-/y) male mouse model. Wild type and HDAC6-deficient male mice were administered 3,5 diethoxicarbonyl-1,4 dihydrocollidine (DDC) to induce DRs. The impact of HDAC6 inhibition on aggresome formation was assessed in vitro using AML-12 hepatocytes exposed to H2O2 and treated with tubastatin A (TSA), a selective HDAC6 inhibitor. Fluorescence immunohistochemistry and quantitative real-time polymerase chain reaction (qRT-PCR) were employed to quantify protein and gene expression levels, respectively. Immunohistochemical and qRT-PCR analyses revealed that HDAC6 deficiency exacerbated DRs and fibrosis, accompanied by increased expression of transforming growth factor β (TGF-β) and activation of the Notch signaling pathway. Additionally, genetic knockout or pharmacological inhibition of HDAC6 promoted hepatocyte apoptosis in vivo and in vitro, as evidenced by elevated caspase3, caspase9, and p53 expression. Furthermore, TSA treatment induced the formation of aggresomes in H2O2-exposed AML-12 hepatocytes, which were encased by vimentin filaments. These findings demonstrate that HDAC6 deficiency promotes DRs and liver fibrosis through the formation of intracellular aggregates, ultimately leading to hepatocyte apoptosis.

The Mechanisms and Therapeutic Implications of PI3K Signaling in Airway Inflammation and Remodeling in Asthma

Bronchial asthma is a complex and heterogeneous disease with ongoing airway inflammation and increased airway responsiveness. Key characteristics of the disease include persistent airway inflammation, airway hyperresponsiveness, and airway remodeling. Asthma's chronic and recurrent characteristics contribute to airway remodeling and inflammation, which can exacerbate lung damage. Presently, inflammation is predominantly managed with corticosteroids, yet there is a notable absence of treatments specifically addressing airway remodeling. The phosphoinositide 3-kinase (PI3K) signaling pathway is integral to the processes of inflammation, airway remodeling, and immune responses. Pharmacological agents targeting this pathway are currently undergoing clinical evaluation. This review elucidates the role of PI3K in the immune responses, airway inflammation, and remodeling associated with asthma, examining its underlying mechanisms. Furthermore, we synthesize the existing literature on the therapeutic potential of PI3K inhibitors for asthma management, emphasizing immune modulation, airway inflammation, and remodeling, including drug development and ongoing clinical trials. Lastly, we explore how various PI3K-targeted therapies may enhance efficacy and improve tolerance.

Spirotetrahydroisoquinoline-Based Histone Deacetylase Inhibitors as New Antifibrotic Agents: Biological Evaluation in Human Fibroblasts from Bronchoalveolar Lavages of Idiopathic Pulmonary Fibrosis Patients

Idiopathic pulmonary fibrosis (IPF) is a rare interstitial lung disease typified by a progressive fibrosing phenotype. IPF has been associated with aberrant HDAC activity, particularly HDAC6. Combining synthetic and modeling studies, a new family of spirotetrahydroisoquinoline-capped histone deacetylase inhibitors 5a-o was developed. These analogues were prepared via the three-component Castagnoli-Cushman reaction (CCR) as the key step. Structure-activity relationship (SAR) studies identified 5n (fibrostat) as a preferential HDAC6 inhibitor with a suitable degree of selectivity compared to HDAC1, HDAC3, HDAC5, HDAC8, HDAC10, and HDAC11. 5n was able to negatively modulate the expression of fibrotic markers, fibronectin and collagen 1, in fibroblasts derived from bronchoalveolar lavages of IPF patients. In another ex vivo IPF human model, 5n (fibrostat) reduced the expression of fibronectin and negatively affected the expression of collagen 1 and vimentin, the latter being associated with invasiveness. Finally, fibrostat did not show toxicity in rat-perfused heart and zebrafish larvae.

Recent advances in TGF-β signaling pathway in COVID-19 pathogenesis: A review

The coronavirus disease 2019 (COVID-19) has resulted in approximately 7.0 million fatalities between 2019 and 2022, underscoring a pressing need for comprehensive research into its underlying mechanisms and therapeutic avenues. A distinctive feature of severe COVID-19 is the dysregulated immune response characterized by excessive activation of immune cells and the consequent cytokine storms. Recent advancements in our understanding of cellular signaling pathways have illuminated the role of Transforming Growth Factor Beta (TGF-β) as a pivotal signaling molecule with significant implications for the pathogenesis of infectious diseases, including COVID-19. Emerging evidence reveals that TGF-β signaling, when activated by viral components or secondary pathways, adversely affects diverse cell types, particularly immune cells, and lung tissue, leading to complications such as pulmonary fibrosis. In our review article, we critically evaluate recent literature on the involvement of TGF-β signaling in the progression of COVID-19. We discuss a range of pharmacological interventions, including nintedanib, pirfenidone, corticosteroids, proton pump inhibitors, and histone deacetylase inhibitors, and their potential to modulate the TGF-β pathway in the context of COVID-19 treatment. Additionally, we explore ongoing clinical trials involving mesenchymal stem cells, low-dose radiation therapy, and artemisinin derivatives to assess their impact on TGF-β levels and subsequent clinical outcomes in COVID-19 patients. This review is particularly relevant at this juncture as the global health community continues to grapple with the ramifications of the COVID-19 pandemic, highlighting the urgent need for targeted therapeutic strategies aimed at TGF-β modulation to mitigate disease severity and improve patient outcomes.

Histone deacetylase 6 inhibition promotes microtubule acetylation and facilitates autophagosome-lysosome fusion in dystrophin-deficient mdx mice

AIM

Duchenne muscular dystrophy is a progressive muscle-wasting disease caused by mutations in the dystrophin gene. Despite progress in dystrophin-targeted gene therapies, it is still a fatal disease requiring novel therapeutics that can be used synergistically or alternatively to emerging gene therapy. Defective autophagy and disorganized microtubule networks contribute to dystrophic pathogenesis, yet the mechanisms by which microtubule alterations regulate autophagy remain elusive. The present study was designed to uncover possible mechanisms underpinning the role of microtubules in regulating autophagy in dystrophic mice.

METHODS

Mdx mice were also supplemented with Tubastatin A, a pharmacological inhibitor of histone deacetylase 6, and pathophysiology was assessed. Mdx mice with a genetic deletion of the Nox-2 scaffolding subunit p47phox were used to assess redox dependence on tubulin acetylation.

RESULTS

Our data show decreased acetylation of α-tubulin with enhanced histone deacetylase 6 expression. Tubastatin A increases tubulin acetylation and Q-SNARE complex formation but does not alter microtubule organization or density, indicating improved autophagosome-lysosome fusion. Tubastatin A increases the acetylation of peroxiredoxin and protects it from hyper-oxidation, hence modulating intracellular redox status in mdx mice. Tubastatin A reduces muscle damage and enhances force production. Genetic down regulation of Nox2 activity in the mdx mice promotes autophagosome maturation but not autolysosome formation.

CONCLUSION

Our data highlight that autophagy is differentially regulated by redox and acetylation in mdx mice. By improving autophagy through promoting tubulin acetylation, Tubastatin A decreases the dystrophic phenotype and improves muscle function, suggesting a great potential for clinical translation and treating dystrophic patients.

Therapeutic role of histone deacetylase inhibition in an in vitro model of Graves' orbitopathy

Graves' orbitopathy (GO), a manifestation of Graves' disease, is characterized by orbital fibroblast‑induced inflammation, leading to fibrosis or adipogenesis. Histone deacetylase (HDAC) serves a central role in autoimmune diseases and fibrosis. The present study investigated HDAC inhibition in orbital fibroblasts from patients with GO to evaluate its potential as a therapeutic agent. Primary cultured orbital fibroblasts were treated with an HDAC inhibitor, panobinostat, under the stimulation of IL‑1β, TGF‑β or adipogenic medium. Inflammatory cytokines, and fibrosis‑ and adipogenesis‑related proteins were analyzed using western blotting. The effects of panobinostat on HDAC mRNA expression were measured in GO orbital fibroblasts, and specific HDACs were inhibited using small interfering RNA transfection. Panobinostat significantly reduced the IL‑1β‑induced production of inflammatory cytokines and TGF‑β‑induced production of fibrosis‑related proteins. It also suppressed adipocyte differentiation and adipogenic transcription factor production. Furthermore, it significantly attenuated HDAC7 mRNA expression in GO orbital fibroblasts. In addition, the silencing of HDAC7 led to anti‑inflammatory and anti‑fibrotic effects. In conclusion, by inhibiting HDAC7 gene expression, panobinostat may suppress the production of inflammatory cytokines, profibrotic proteins and adipogenesis in GO orbital fibroblasts. The present in vitro study suggested that HDAC7 could be a potential therapeutic target for inhibiting the inflammatory, adipogenic and fibrotic mechanisms of GO.

HBx-induced upregulation of MAP1S drives hepatocellular carcinoma proliferation and migration via MAP1S/Smad/TGF-β1 loop

Hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC), has a significantly higher risk of recurrence. However, the exact mechanism by which HBV prompts HCC recurrence remains largely unknown. In this study liver microarray test revealed significant upregulation of microtubule associated protein 1S (MAP1S) in metastatic HCC compared to control. MAP1S knockdown suppressed growth of HCCLM3 cells in vitro and in vivo. Mechanistically, HBV-encoded X protein (HBx) upregulates MAP1S, which enhances microtubule (MT) acetylation by promoting the degradation of histone deacetylase 6 (HDAC6), and facilitates the nuclear translocation of Smad complex, and thereby enhancing downstream TGF-β signaling. Smad complex, in turn, increases MAP1S, establishing a feedback loop of MAP1S/Smad/TGF-β1. Finally, survival analysis of 150 HBV-associated HCC patients demonstrated both increased MAP1S and decreased HDAC6 were significantly associated with shorter relapse-free survival. Collectively, this study reveals a unique mechanism whereby HBx-induced upregulation of MAP1S drives HBV-related HCC proliferation and migration through the MAP1S/Smad/TGF-β1 feedback loop. TEASER: MAP1S is a key link between HBV infection and a higher risk of metastatic recurrence of HCC.

Understanding the molecular regulatory mechanisms of autophagy in lung disease pathogenesis

Lung disease development involves multiple cellular processes, including inflammation, cell death, and proliferation. Research increasingly indicates that autophagy and its regulatory proteins can influence inflammation, programmed cell death, cell proliferation, and innate immune responses. Autophagy plays a vital role in the maintenance of homeostasis and the adaptation of eukaryotic cells to stress by enabling the chelation, transport, and degradation of subcellular components, including proteins and organelles. This process is essential for sustaining cellular balance and ensuring the health of the mitochondrial population. Recent studies have begun to explore the connection between autophagy and the development of different lung diseases. This article reviews the latest findings on the molecular regulatory mechanisms of autophagy in lung diseases, with an emphasis on potential targeted therapies for autophagy.

Pharmacological targets and validation of remdesivir for the treatment of COVID-19-associated pulmonary fibrosis: A network-based pharmacology and bioinformatics study

The objective of this study was to employ bioinformatics and network pharmacology methodologies to investigate the targets and molecular mechanisms of remdesivir in the treatment of coronavirus disease 2019 (COVID-19)-associated pulmonary fibrosis (PF). Several open-source databases were utilized to confirm the shared targets of remdesivir, COVID-19, and PF. Following this, a comprehensive analysis incorporating function enrichment, protein-protein interaction (PPI), transcription factor (TF), and molecular docking was conducted to investigate the potential mechanisms underlying the effectiveness of remdesivir in the treatment of COVID-19-associated PF. The initial validation of these findings was performed using publicly available histological and single-cell sequencing databases. The functional enrichment analysis revealed a strong association between remdesivir and viral defense, inflammatory response, and immune response. The key pathways identified in the study were transforming growth factor (TGF-β), PI3K-Akt, mTOR, MAPK, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor resistance, HIF-1, and Toll-like receptor signaling pathways. Additionally, the PPI analysis demonstrated the network relationships of 13 important targets, while the TF analysis provided valuable insights into the regulatory networks of these targets. Among the identified TFs, RELA was found to be the most significant. To validate our findings, we utilized publicly available histological and single-cell sequencing databases, successfully confirming the involvement of 8 key targets, including AKT1, EGFR, RHOA, MAPK1, PIK3R1, MAPK8, MAPK14, and MTOR. Furthermore, molecular docking studies were conducted to assess the interaction between remdesivir and the identified key targets, thus confirming its effective targeting effects. Remdesivir has the potential to exert antiviral, anti-inflammatory, and immunomodulatory effects in the context of COVID-19-associated PF.

BRD3308 suppresses macrophage oxidative stress and pyroptosis via upregulating acetylation of H3K27 in sepsis-induced acute lung injury

Background

Sepsis-induced acute lung injury (ALI) leads to severe hypoxemia and respiratory failure, contributing to poor prognosis in septic patients. Endotoxin dissemination triggers oxidative stress and the release of inflammatory cytokines in macrophages, initiating diffuse alveolar damage. The role of epigenetic histone modifications in organ injury is increasingly recognized. The present study aimed to investigate the use of a histone modification inhibitor to alleviate sepsis-induced ALI, revealing a new strategy for improving sepsis patient survival.

Methods

In vivo models of ALI were established through the intraperitoneal injection of lipopolysaccharide and cecal ligation and puncture surgery. Furthermore, the disease process was simulated in vitro by stimulating Tamm-Horsfall protein-1 (THP-1) cells with lipopolysaccharide. Hematoxylin and eosin staining, blood gas analysis and pulmonary function tests were utilized to assess the extent of lung tissue damage. Western blot analysis, real-time polymerase chain reaction, enzyme-linked immunosorbent assay and immunofluorescence were used to measure the levels and distribution of the indicated indicators within cells and tissues. Reactive oxygen species and autophagic flux alterations were detected using specific probes.

Results

BRD3308, which is a inhibitor of histone deacetylase 3, improved lung tissue damage, inflammatory infiltration and edema in ALI by inhibiting Nod-like receptor protein3-mediated pyroptosis in macrophages. By upregulating autophagy, BRD3308 improved the disruption of redox balance in macrophages and reduced the accumulation of reactive oxygen species. Mechanistically, BRD3308 inhibited histone deacetylase 3 activity by binding to it and altering its conformation. Following histone deacetylase 3 inhibition, acetylation of H3K27 was significantly increased. Moreover, the increase in H3K27Ac led to the upregulation of autophagy-related gene 5, a key component of autophagosomes, thereby activating autophagy.

Conclusions

BRD3308 inhibits oxidative stress and pyroptosis in macrophages by modulating histone acetylation, thereby preventing sepsis-induced ALI. The present study provides a potential strategy and theoretical basis for the clinical treatment of sepsis-induced ALI.

Resveratrol reinforces the therapeutic effect of mesenchymal stem cell (MSC)-derived exosomes against renal ischemia‒reperfusion injury (RIRI)-associated fibrosis by suppressing TGF-β-induced epithelial-mesenchymal transition

Resveratrol (RSV) has been shown to prevent epithelial-mesenchymal transition (EMT) in different diseases by modulating several signaling pathways, and RSV can prevent EMT by modulating the signaling of the TGF-β/Smad axis. In the development of renal ischemia‒reperfusion injury (RIRI), RSV and MSC-derived exosomes could ameliorate RIRI via different signaling pathways. In this study, we aimed to investigate the effect of RSV plus MSC-derived exosomes on the prognosis of RIRI. Quantitative real-time polymerase chain reaction (PCR) was performed to measure the expression of E-CAD, SMA, COL10A1, VMT and MMP-7 mRNA in TCMK-1 cells and mice under various conditions. HE and Masson staining were used to evaluate kidney injury and fibrosis in mice under various conditions. RSV effectively maintained the TGF-β- and AA-induced upregulation of E-CAD, SMA, COL10A1, VMT and MMP-7 mRNA expression in TCMK-1 cells. Moreover, MSC-derived exosomes effectively reinforced the effect of RSV on reducing the TGF-β- and AA-induced upregulation of E-CAD, SMA, COL10A1, VMT and MMP-7 mRNA expression in TCMK-1 cells. Furthermore, MSC-derived exosomes enhanced the capability of RSV to maintain the RIRI-induced increases in Cr and BUN, as well as the upregulation of E-CAD, SMA, COL10A1, VMT and MMP-7 mRNA expression in mice. In addition, MSC-derived exosomes enhanced the capability of RSV to decrease RIRI-induced kidney injury and fibrosis in mice. Our findings showed that the administration of MSC-derived exosomes and RSV could suppress the TGF-β-induced epithelial-mesenchymal transition. This suppressive effect was promoted by the coadministration of MSC-derived exosomes and RSV.

Epigenetic regulation of macrophage activation in chronic obstructive pulmonary disease

Macrophages in the innate immune system play a vital role in various lung diseases such as asthma, chronic obstructive pulmonary disease (COPD), acute lung injury and pulmonary fibrosis. Macrophages involved in the process of immunity need to go through a process of activation, including changes in gene expression and cell metabolism. Epigenetic modifications are key factors of macrophage activation including DNA methylation, histone modification and non-coding RNA regulation. Understanding the role and mechanisms of epigenetic regulation of macrophage activation can provide insights into the function of macrophages in lung diseases and help identification of potential therapeutic targets. This review summarizes the latest progress in the epigenetic changes and regulation of macrophages in their development process and in normal physiological states, and the epigenetic regulation of macrophages in COPD as well as the influence of macrophage activation on COPD development.

Histone deacetylases: potential therapeutic targets for idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive disease of unknown origin and the most common interstitial lung disease. However, therapeutic options for IPF are limited, and novel therapies are urgently needed. Histone deacetylases (HDACs) are enzymes that participate in balancing histone acetylation activity for chromatin remodeling and gene transcription regulation. Increasing evidence suggests that the HDAC family is linked to the development and progression of chronic fibrotic diseases, including IPF. This review aims to summarize available information on HDACs and related inhibitors and their potential applications in treating IPF. In the future, HDACs may serve as novel targets, which can aid in understanding the etiology of PF, and selective inhibition of single HDACs or disruption of HDAC genes may serve as a strategy for treating PF.

Tetrandrine Alleviates Silica-induced Pulmonary Fibrosis Through PI3K/AKT Pathway: Network Pharmacology Investigation and Experimental Validation

Tetrandrine (TET) is a bisbenzylisoquinoline alkaloid derived from Stephania tetrandra S. Moor, known for its potential use in attenuating the progression of silicosis. However, the precise effects and underlying mechanisms of TET remain controversial. In this study, we aimed to elucidate the pharmacological mechanism of TET using a network pharmacology approach, while also evaluating its effect on silica-induced lung fibrosis in mice and TGF-β1-stimulated pulmonary fibroblasts in vitro. We employed network pharmacology to unravel the biological mechanisms through which TET may exert its therapeutic effects on pulmonary fibrosis and silicosis. In a silica-induced mouse model of lung fibrosis, TET was administered orally either during the early or late stage of fibrotic progression. Additionally, we examined the effects of TET on fibroblasts stimulated by TGF-β1 in vitro. Through the analysis, we identified a total of 101 targets of TET, 7,851 genes associated with pulmonary fibrosis, and 80 overlapping genes. These genes were primarily associated with key pathways such as epidermal growth factor receptor tyrosine kinase inhibitor resistance, the vascular endothelial growth factor signaling pathway, and the phosphatidylinositol 3 kinase (PI3K)-protein kinase B (PKB or AKT) signaling pathway. Furthermore, molecular docking analysis revealed the binding of TET to AKT1, the catalytic subunit of phosphatidylinositol-3 kinase, and KDR. In vivo experiments demonstrated that TET significantly alleviated silica-induced pulmonary fibrosis and reduced the expression of fibrotic markers. Moreover, TET exhibited inhibitory effects on the migration, proliferation, and differentiation of TGF-β1-induced lung fibroblasts in vitro. Notably, TET mitigated silica-induced pulmonary fibrosis by suppressing the PI3K/AKT pathway. In conclusion, our findings suggest that TET possesses the ability to suppress silica-induced pulmonary fibrosis by targeting the PI3K/AKT signaling pathway. These results provide valuable insights into the therapeutic potential of TET in the treatment of pulmonary fibrosis and silicosis.

Advances in the Study of Non-Coding RNA in the Signaling Pathway of Pulmonary Fibrosis

Pulmonary fibrosis is a group of chronic, progressive, and irreversible interstitial lung diseases, which are common to most end-stage lung diseases and are one of the most difficult diseases of the respiratory system. In recent years, due to the frequent occurrence of air pollution and smog, the incidence of pulmonary fibrosis in China has increased year by year, the morbidity and mortality rates of pulmonary fibrosis have gradually increased and the age of the disease tends to be younger. However, the pathogenesis of pulmonary fibrosis is not yet fully understood and is needed to further explore new drug targets. Studies have shown that non-coding RNAs play an important role in regulating the process of pulmonary fibrosis, non-coding RNAs and their specifically expressed can promote or inhibit the process. Here, we review the role of some in the regulation of pulmonary fibrosis signaling pathways and provide new ideas for the clinical diagnosis and treatment of pulmonary fibrosis.

Central inhibition of HDAC6 re-sensitizes leptin signaling during obesity to induce profound weight loss

Leptin resistance during excess weight gain significantly contributes to the recidivism of obesity to leptin-based pharmacological therapies. The mechanisms underlying the inhibition of leptin receptor (LepR) signaling during obesity are still elusive. Here, we report that histone deacetylase 6 (HDAC6) interacts with LepR, reducing the latter's activity, and that pharmacological inhibition of HDAC6 activity disrupts this interaction and augments leptin signaling. Treatment of diet-induced obese mice with blood-brain barrier (BBB)-permeable HDAC6 inhibitors profoundly reduces food intake and leads to potent weight loss without affecting the muscle mass. Genetic depletion of Hdac6 in Agouti-related protein (AgRP)-expressing neurons or administration with BBB-impermeable HDAC6 inhibitors results in a lack of such anti-obesity effect. Together, these findings represent the first report describing a mechanistically validated and pharmaceutically tractable therapeutic approach to directly increase LepR activity as well as identifying centrally but not peripherally acting HDAC6 inhibitors as potent leptin sensitizers and anti-obesity agents.

The role of epithelial cells in fibrosis: Mechanisms and treatment

Fibrosis is a pathological process that affects multiple organs and is considered one of the major causes of morbidity and mortality in multiple diseases, resulting in an enormous disease burden. Current studies have focused on fibroblasts and myofibroblasts, which directly lead to imbalance in generation and degradation of extracellular matrix (ECM). In recent years, an increasing number of studies have focused on the role of epithelial cells in fibrosis. In some cases, epithelial cells are first exposed to external physicochemical stimuli that may directly drive collagen accumulation in the mesenchyme. In other cases, the source of stimulation is mainly immune cells and some cytokines, and epithelial cells are similarly altered in the process. In this review, we will focus on the multiple dynamic alterations involved in epithelial cells after injury and during fibrogenesis, discuss the association among them, and summarize some therapies targeting changed epithelial cells. Especially, epithelial mesenchymal transition (EMT) is the key central step, which is closely linked to other biological behaviors. Meanwhile, we think studies on disruption of epithelial barrier, epithelial cell death and altered basal stem cell populations and stemness in fibrosis are not appreciated. We believe that therapies targeted epithelial cells can prevent the progress of fibrosis, but not reverse it. The epithelial cell targeting therapies will provide a wonderful preventive and delaying action.

A narrative review of the role of HDAC6 in idiopathic pulmonary fibrosis

Background and Objective

Idiopathic pulmonary fibrosis (IPF) is a progressive and irreversible condition characterized by the deposition of extracellular matrix resulting from repetitive damage to the alveolar epithelium. These injuries, along with dysregulated wound repair and fibroblast dysfunction, lead to continuous tissue remodeling and fibrosis, eventually resulting in end-stage pulmonary fibrosis. Currently, there is no specific pharmacological treatment available for IPF. The role of inflammation in the development of IPF is still a topic of debate, and it is sometimes considered incidental to fibrosis. Over the past decade, macrophages have emerged as significant contributors to the pathogenesis of fibrosis. M1 macrophages are responsible for wound healing following alveolar epithelial injury, while M2 macrophages are involved in resolving wound repair and terminating the inflammatory response in the lungs. Various studies provide evidence that M2-like macrophages contribute to the abnormal fibrogenesis. In recent years, there has been growing interest in understanding macrophage polarization and its role in the development of pulmonary fibrosis. Histone deacetylase 6 (HDAC6), a member of the HDAC family with two functional deacetylase structural domains and a ubiquitin-binding zinc finger structural domain (ZnF-BUZ), plays a crucial role in pulmonary fibrosis. This article explores the role of HDAC6 in pulmonary fibrosis and evaluates its potential as a treatment approach for IPF.

Methods

PubMed, Cochrane Library, China National Knowledge Infrastructure (CNKI), Wanfang, China Biomedical Literature Service System (CBMdisc) and Web of Science were searched to obtain researches, published in English and Chinese, until July 2023. The search was performed using specific keywords such as Histone deacetylase 6, HDAC6, Idiopathic pulmonary fibrosis, IPF, fibrosis.

Key Content and Findings

HDAC6 has diverse effects on physiological processes, including the NLRP3 inflammasome, epithelial-mesenchymal transition, the TGFβ-PI3K-AKT pathway, macrophage polarization and TGF-β-Smad signaling pathway, due to its unique structure. HDAC6 has been found to enhance the inflammatory response and fibrosis of lung tissues, contributing to the development of IPF.

Conclusions

In the future, HDAC6 inhibitors are expected to play a crucial role in the treatment of fibrotic disorders and should be studied further deserves to pursue in future research.

Targeting histone deacetylase 9 represses fibrogenic phenotypes in buccal mucosal fibroblasts with arecoline stimulation

Background/purpose

Oral submucosal fibrosis (OSF) is a premalignant disorder positively associated with betel nut chewing. Recent studies supported the promising benefits of histone deacetylase (HDAC) inhibitors for fibrosis treatment. Here we aim to clarify the pro-fibrogenic role of HDAC9 in regulating OSF.

Materials and methods

Healthy and OSF specimens were collected to investigate the clinical significance of HDAC9. Chronic arecoline treatment process was used to induce arecoline-mediated myofibroblasts-related activation of primary buccal mucosa fibroblasts (BMFs). Functional analysis of collagen gel contraction, transwell migration, and wound-healing assays were performed to assess the change in pro-fibrogenic properties of BMFs and fibrotic BMFs (fBMFs). Lentiviral-mediated HDAC9 knockdown was used to verify the role of HDAC9 in the pro-fibrogenic process.

Results

We found that arecoline significantly increased the mRNA and protein expression of HDAC9 of BMFs in a dose-dependent manner. Knockdown of HDAC9 in BMFs reversed the strengthened effects of arecoline on collagen gel contraction, cell migration, and wound-healing ability. We further demonstrated that knockdown of HDAC9 in fBMFs significantly attenuated its inherent pro-fibrogenic properties. Furthermore, we confirmed a significantly increased expression of HDAC9 mRNA in OSF compared to normal tissues, which suggested a positive correlation between the up-regulation of HDAC9 and OSF.

Conclusion

We demonstrated that silencing of HDAC9 inhibited arecoline-induced activation and inherent pro-fibrogenic properties, suggesting potential therapeutics by targeting HDAC9 in the OSF treatment.

ACY-241, a histone deacetylase 6 inhibitor, suppresses the epithelial-mesenchymal transition in lung cancer cells by downregulating hypoxia-inducible factor-1 alpha

Hypoxia-inducible factor-1 alpha (HIF-1α) is a transcription factor activated under hypoxic conditions, and it plays a crucial role in cellular stress regulation. While HIF-1α activity is essential in normal tissues, its presence in the tumor microenvironment represents a significant risk factor as it can induce angiogenesis and confer resistance to anti-cancer drugs, thereby contributing to poor prognoses. Typically, HIF-1α undergoes rapid degradation in normoxic conditions via oxygen-dependent degradation mechanisms. However, certain cancer cells can express HIF-1α even under normoxia. In this study, we observed an inclination toward increased normoxic HIF-1α expression in cancer cell lines exhibiting increased HDAC6 expression, which prompted the hypothesis that HDAC6 may modulate HIF-1α stability in normoxic conditions. To prove this hypothesis, several cancer cells with relatively higher HIF-1α levels under normoxic conditions were treated with ACY-241, a selective HDAC6 inhibitor, and small interfering RNAs for HDAC6 knockdown. Our data revealed a significant reduction in HIF-1α expression upon HDAC6 inhibition. Moreover, the downregulation of HIF-1α under normoxic conditions decreased zinc finger E-box-binding homeobox 1 expression and increased E-cadherin levels in lung cancer H1975 cells, consequently suppressing cell invasion and migration. ACY-241 treatment also demonstrated an inhibitory effect on cell invasion and migration by reducing HIF-1α level. This study confirms that HDAC6 knockdown and ACY-241 treatment effectively decrease HIF-1α expression under normoxia, thereby suppressing the epithelial-mesenchymal transition. These findings highlight the potential of selective HDAC6 inhibition as an innovative therapeutic strategy for lung cancer.

The CEBPA-FGF21 regulatory network may participate in the T2DM-induced skeletal muscle atrophy by regulating the autophagy-lysosomal pathway

AIMS

Recent years have witnessed an increasing research interest in the roles of transcription factor (TF)-gene regulatory network in type 2 diabetes mellitus (T2DM). Thus, we sought to characterize the mechanistic insights based on the TF-gene regulatory network in skeletal muscle atrophy in T2DM.

METHODS

Differentially expressed TFs (DETFs) and mRNAs (DEmRNAs) were obtained in T2DM-related gene expression profiles (GSE12643, GSE55650, GSE166502, and GSE29221), followed by WGCNA, and GO and KEGG enrichment analyses. Next, the iRegulon plug-in unit of Cytoscape software was used to construct a TF-mRNA regulatory network. Besides, RT-qPCR and ChIP-seq were utilized to measure the expression of CEBPA and FGF21 in the skeletal muscle tissues or cells of T2DM rat models. At last, the effect of overexpression of FGF21 on the autophagy-lysosomal pathway was examined in skeletal muscle cells of T2DM rats.

RESULTS

Totally, 12 DETFs and 102 DEmRNAs were found in the skeletal muscle tissues of T2DM samples. The DEmRNAs were mainly enriched in the autophagy-lysosomal pathway. CEBPA affected the skeletal muscle atrophy in T2DM by regulating 5 target genes via the autophagy-lysosomal pathway. CEBPA could target FGF21. In addition, the expression of CEBPA was elevated, while the expression of FGF21 was diminished in the skeletal muscle tissues or cells of T2DM rats. The CEBPA-FGF21 regulatory network promoted skeletal muscle atrophy in T2DM by activating the autophagy-lysosomal pathway.

CONCLUSION

The CEBPA-FGF21 regulatory network may participate in the T2DM-induced skeletal muscle atrophy by regulating the autophagy-lysosomal pathway. Thus, our study provides interesting targets for prevention of skeletal muscle atrophy in T2DM.

Epigenetic hallmarks in pulmonary fibrosis: New advances and perspectives

Epigenetics indicates that certain phenotypes of an organism can undergo heritable changes in the absence of changes in the genetic DNA sequence. Many studies have shown that epigenetic patterns play an important role in the lung and lung diseases. Pulmonary fibrosis (PF) is also a type of lung disease. PF is an end-stage change of a large group of lung diseases, characterized by fibroblast proliferation and massive accumulation of extracellular matrix, accompanied by inflammatory injury and histological destruction, that is, structural abnormalities caused by abnormal repair of normal alveolar tissue. It causes loss of lung function in patients with multiple complex diseases, leading to respiratory failure and subsequent death. However, current treatment options for IPF are very limited and no drugs have been shown to significantly prolong the survival of patients. Therefore, based on a systematic understanding of the disease mechanisms of PF, this review integrates the role of epigenetics in the development and course of PF, describes preventive and potential therapeutic targets for PF, and provides a theoretical basis for further exploration of the mechanisms of PF.

Tangeretin attenuates bleomycin-induced pulmonary fibrosis by inhibiting epithelial-mesenchymal transition via the PI3K/Akt pathway

Background: Pulmonary fibrosis (PF) is a terminal pathological change in a variety of lung diseases characterized by excessive deposition of extracellular matrix, for which effective treatment is lacking. Tangeretin (Tan), a flavonoid derived from citrus, has been shown to have a wide range of pharmacological effects. This study aimed to investigate the role and potential mechanisms of Tan on pulmonary fibrosis. Methods: A model of pulmonary fibrosis was established by administering bleomycin through tracheal drip, followed by administering Tan or pirfenidone through gavage. HE and Masson staining were employed to assess the extent of pulmonary fibrosis. Subsequently, Western blot, enzyme-linked immunosorbent assay (ELISA), RNA sequencing, and immunohistochemistry techniques were employed to uncover the protective mechanism of Tan in PF mice. Furthermore, A549 cells were stimulated with TGF-β1 to induce epithelial-mesenchymal transition (EMT) and demonstrate the effectiveness of Tan in mitigating PF. Results: Tan significantly ameliorated bleomycin-induced pulmonary fibrosis, improved fibrotic pathological changes, and collagen deposition in the lungs, and reduced lung inflammation and oxidative stress. The KEGG pathway enrichment analysis revealed a higher number of enriched genes in the PI3K/Akt pathway. Additionally, Tan can inhibit the EMT process related to pulmonary fibrosis. Conclusion: Taken together, the above research results indicate that Tan suppresses inflammation, oxidative stress, and EMT in BLM-induced pulmonary fibrosis via the PI3K/Akt pathway and is a potential agent for the treatment of pulmonary fibrosis.

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.

HDAC6 inhibition: a significant potential regulator and therapeutic option to translate into clinical practice in renal transplantation

Histone deacetylase 6 (HDAC6), an almost exclusively cytoplasmic enzyme, plays an essential role in many biological processes and exerts its deacetylation-dependent/independent effects on a variety of target molecules, which has contributed to the flourishing growth of relatively isoform-specific enzyme inhibitors. Renal transplantation (RT) is one of the alternatively preferred treatments and the most cost-effective treatment approaches for the great majority of patients with end-stage renal disease (ESRD). HDAC6 expression and activity have recently been shown to be increased in kidney disease in a number of studies. To date, a substantial amount of validated studies has identified HDAC6 as a pivotal modulator of innate and adaptive immunity, and HDAC6 inhibitors (HDAC6i) are being developed and investigated for use in arrays of immune-related diseases, making HDAC6i a promising therapeutic candidate for the management of a variety of renal diseases. Based on accumulating evidence, HDAC6i markedly open up new avenues for therapeutic intervention to protect against oxidative stress-induced damage, tip the balance in favor of the generation of tolerance-related immune cells, and attenuate fibrosis by inhibiting multiple activations of cell profibrotic signaling pathways. Taken together, we have a point of view that targeting HDAC6 may be a novel approach for the therapeutic strategy of RT-related complications, including consequences of ischemia-reperfusion injury, induction of immune tolerance in transplantation, equilibrium of rejection, and improvement of chronic renal graft interstitial fibrosis after transplantation in patients. Herein, we will elaborate on the unique function of HDAC6, which focuses on therapeutical mechanism of action related to immunological events with a general account of the tantalizing potential to the clinic.

COPD Patients Exhibit Distinct Gene Expression, Accelerated Cellular Aging, and Bias to M2 Macrophages

COPD, one of world's leading contributors to morbidity and mortality, is characterized by airflow limitation and heterogeneous clinical features. Three main phenotypes are proposed: overlapping asthma/COPD (ACO), exacerbator, and emphysema. Disease severity can be classified as mild, moderate, severe, and very severe. The molecular basis of inflammatory amplification, cellular aging, and immune response are critical to COPD pathogenesis. Our aim was to investigate EP300 (histone acetylase, HAT), HDAC 2 (histone deacetylase), HDAC3, and HDAC4 gene expression, telomere length, and differentiation ability to M1/M2 macrophages. For this investigation, 105 COPD patients, 42 smokers, and 73 non-smoker controls were evaluated. We identified a reduced HDAC2 expression in patients with mild, moderate, and severe severity; a reduced HDAC3 expression in patients with moderate and severe severity; an increased HDAC4 expression in patients with mild severity; and a reduced EP300 expression in patients with severe severity. Additionally, HDAC2 expression was reduced in patients with emphysema and exacerbator, along with a reduced HDAC3 expression in patients with emphysema. Surprisingly, smokers and all COPD patients showed telomere shortening. COPD patients showed a higher tendency toward M2 markers. Our data implicate genetic changes in COPD phenotypes and severity, in addition to M2 prevalence, that might influence future treatments and personalized therapies.

PRDX1 negatively regulates bleomycin-induced pulmonary fibrosis via inhibiting the epithelial-mesenchymal transition and lung fibroblast proliferation in vitro and in vivo

BACKGROUND

Pulmonary fibrosis is a major category of end-stage changes in lung diseases, characterized by lung epithelial cell damage, proliferation of fibroblasts, and accumulation of extracellular matrix. Peroxiredoxin 1 (PRDX1), a member of the peroxiredoxin protein family, participates in the regulation of the levels of reactive oxygen species in cells and various other physiological activities, as well as the occurrence and development of diseases by functioning as a chaperonin.

METHODS

Experimental methods including MTT assay, morphological observation of fibrosis, wound healing assay, fluorescence microscopy, flow cytometry, ELISA, western blot, transcriptome sequencing, and histopathological analysis were used in this study.

RESULTS

PRDX1 knockdown increased ROS levels in lung epithelial cells and promoted epithelial-mesenchymal transition (EMT) through the PI3K/Akt and JNK/Smad signalling pathways. PRDX1 knockout significantly increased TGF-β secretion, ROS production, and cell migration in primary lung fibroblasts. PRDX1 deficiency also increased cell proliferation, cell cycle circulation, and fibrosis progression through the PI3K/Akt and JNK/Smad signalling pathways. BLM treatment induced more severe pulmonary fibrosis in PRDX1-knockout mice, mainly through the PI3K/Akt and JNK/Smad signalling pathways.

CONCLUSIONS

Our findings strongly suggest that PRDX1 is a key molecule in BLM-induced lung fibrosis progression and acts through modulating EMT and lung fibroblast proliferation; therefore, it may be a therapeutic target for the treatment of BLM-induced lung fibrosis.

Local Lung Fibroblast Autophagy in the Context of Lung Fibrosis Pathogenesis

Abstract:

The current molecular advances in lung fibrosis pathogenesis distend beyond the cellular to involve subcellular and molecular levels. Lung fibrogenesis and autophagy impairment are tight-ly associated. Autophagy is involved in cell cycle control and regulation of the intracellular micro-environment. Degradation of impaired intracellular organelles and biproducts is crucial to maintain-ing a healthy cell and preventing its metaplasia / transdifferentiation to a pathological cell. Autoph-agy modifies the metabolism of alveolar epithelial cells, endothelial cells, and lung fibroblasts. Au-tophagy upregulation induces local lung fibroblast hyperactivity and fibrosis. Several molecular triggers were found to induce lung fibroblast autophagy including TGFβ by inhibition of the PI3K/AKT/mTOR. However, physiologically, a balance is retained between autophagy inducers and inhibitors. Each type of autophagy plays its role in the initiation and progression of lung fibro-sis. The pathogenesis of pulmonary fibrosis is multifactorial and involves dysfunction / dysregula-tion of alveolar epithelial cells, fibroblasts, monocyte-derived macrophages, and endothelial cells. The deposition of extracellular matrix proteins, the remodeling of the lung architecture and the mo-lecular changes include impaired glycolysis, mitochondrial oxidation, gene expression modification, altered phospholipid and sphingolipid metabolism, and dysregulated protein folding lead to repro-gramming of lung fibroblast into myofibroblast and their activation. The paper thoroughly addresses the molecular triggers and inhibitors of lung fibroblast autophagy in lung fibrosis.

Pharmacological inhibition of HDAC6 improves muscle phenotypes in dystrophin-deficient mice by downregulating TGF-β via Smad3 acetylation

The absence of dystrophin in Duchenne muscular dystrophy disrupts the dystrophin-associated glycoprotein complex resulting in skeletal muscle fiber fragility and atrophy, associated with fibrosis as well as microtubule and neuromuscular junction disorganization. The specific, non-conventional cytoplasmic histone deacetylase 6 (HDAC6) was recently shown to regulate acetylcholine receptor distribution and muscle atrophy. Here, we report that administration of the HDAC6 selective inhibitor tubastatin A to the Duchenne muscular dystrophy, mdx mouse model increases muscle strength, improves microtubule, neuromuscular junction, and dystrophin-associated glycoprotein complex organization, and reduces muscle atrophy and fibrosis. Interestingly, we found that the beneficial effects of HDAC6 inhibition involve the downregulation of transforming growth factor beta signaling. By increasing Smad3 acetylation in the cytoplasm, HDAC6 inhibition reduces Smad2/3 phosphorylation, nuclear translocation, and transcriptional activity. These findings provide in vivo evidence that Smad3 is a new target of HDAC6 and implicate HDAC6 as a potential therapeutic target in Duchenne muscular dystrophy.

Effects of Different Concentrations of Oil Mist Particulate Matter on Pulmonary Fibrosis In Vivo and In Vitro

Oil-mist particulate matter (OMPM) refers to oily particles with a small aerodynamic equivalent diameter in ambient air. Since the pathogenesis of pulmonary fibrosis (PF) has not been fully elucidated, this study aims to explore the potential molecular mechanisms of the adverse effects of exposure to OMPM at different concentrations in vivo and in vitro on PF. In this study, rats and cell lines were treated with different concentrations of OMPM in vivo and in vitro. Sirius Red staining analysis shows that OMPM exposure could cause pulmonary lesions and fibrosis symptoms. The expression of TGF-β1, α-SMA, and collagen I was increased in the lung tissue of rats. The activities of MMP2 and TIMP1 were unbalanced, and increased N-Cadherin and decreased E-Cadherin upon OMPM exposure in a dose-dependent manner. In addition, OMPM exposure could activate the TGF-β1/Smad3 and TGF-β1/MAPK p38 signaling pathways, and the differentiation of human lung fibroblast HFL-1 cells. Therefore, OMPM exposure could induce PF by targeting the lung epithelium and fibroblasts, and activating the TGF-β1/Smad3 and TGF-β1/MAPK p38 signaling pathways.

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.

Research Progress in the Molecular Mechanisms, Therapeutic Targets, and Drug Development of Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease. Recent studies have identified the key role of crosstalk between dysregulated epithelial cells, mesenchymal, immune, and endothelial cells in IPF. In addition, genetic mutations and environmental factors (e.g., smoking) have also been associated with the development of IPF. With the recent development of sequencing technology, epigenetics, as an intermediate link between gene expression and environmental impacts, has also been reported to be implicated in pulmonary fibrosis. Although the etiology of IPF is unknown, many novel therapeutic targets and agents have emerged from clinical trials for IPF treatment in the past years, and the successful launch of pirfenidone and nintedanib has demonstrated the promising future of anti-IPF therapy. Therefore, we aimed to gain an in-depth understanding of the underlying molecular mechanisms and pathogenic factors of IPF, which would be helpful for the diagnosis of IPF, the development of anti-fibrotic drugs, and improving the prognosis of patients with IPF. In this study, we summarized the pathogenic mechanism, therapeutic targets and clinical trials from the perspective of multiple cell types, gene mutations, epigenetic and environmental factors.

Revealing the mechanism of Jiegeng decoction attenuates bleomycin-induced pulmonary fibrosis via PI3K/Akt signaling pathway based on lipidomics and transcriptomics

BACKGROUND

Pulmonary fibrosis (PF) is a serious lung disease with unknown etiology and irreversible course. Jiegeng decoction (JGD), a traditional prescription, is widely used to treat lung diseases due to its anti-inflammatory and expectorant effects.

PURPOSE

To explore the effect of JGD on mice with PF and its underlying mechanism. For this purpose, we established a mouse model with PF by bleomycin (BLM) and then administered JGD and pirfenidone at different concentrations.

RESULTS

In vivo, JGD was found to reduce lung inflammation, improve lung function and decrease collagen deposition to alleviate bleomycin-induced PF in mice. The mouse lung tissue was analyzed using lipidomics and transcriptomics. We found phosphatidylinositol was decreased after JGD treatment in lipidomics results, while transcriptomics results showed the critical roles of PI3K/Akt signaling pathway in JGD treatment group. Then, Western Blot and Immunohistochemistry were used to validate that JGD may regulate the expression of Bax, Caspase3, Caspase8, Caspase9 and Bcl-2 apoptosis-related proteins via PI3K/Akt signaling pathway. TUNEL staining revealed that apoptosis mainly occurs on AEC IIs.

CONCLUSION

Our results showed that JGD inhibits apoptosis through the PI3K/Akt signaling pathway, thereby protecting against BLM-induced PF. Hence, JGD is expected to be a potential drug candidate for the treatment of PF.

Targeting Histone Deacetylases in Idiopathic Pulmonary Fibrosis: A Future Therapeutic Option

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal lung disease with limited therapeutic options, and there is a huge unmet need for new therapies. A growing body of evidence suggests that the histone deacetylase (HDAC) family of transcriptional corepressors has emerged as crucial mediators of IPF pathogenesis. HDACs deacetylate histones and result in chromatin condensation and epigenetic repression of gene transcription. HDACs also catalyse the deacetylation of many non-histone proteins, including transcription factors, thus also leading to changes in the transcriptome and cellular signalling. Increased HDAC expression is associated with cell proliferation, cell growth and anti-apoptosis and is, thus, a salient feature of many cancers. In IPF, induction and abnormal upregulation of Class I and Class II HDAC enzymes in myofibroblast foci, as well as aberrant bronchiolar epithelium, is an eminent observation, whereas type-II alveolar epithelial cells (AECII) of IPF lungs indicate a significant depletion of many HDACs. We thus suggest that the significant imbalance of HDAC activity in IPF lungs, with a "cancer-like" increase in fibroblastic and bronchial cells versus a lack in AECII, promotes and perpetuates fibrosis. This review focuses on the mechanisms by which Class I and Class II HDACs mediate fibrogenesis and on the mechanisms by which various HDAC inhibitors reverse the deregulated epigenetic responses in IPF, supporting HDAC inhibition as promising IPF therapy.

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.

PI3K Signaling in Mechanisms and Treatments of Pulmonary Fibrosis Following Sepsis and Acute Lung Injury

Pulmonary fibrosis is a pathological fibrotic process affecting the lungs of five million people worldwide. The incidence rate will increase even more in the next years due to the long-COVID-19 syndrome, but a resolving treatment is not available yet and usually prognosis is poor. The emerging role of the phosphatidylinositol 3-kinase (PI3K)/AKT signaling in fibrotic processes has inspired the testing of drugs targeting the PI3K/Akt pathway that are currently under clinical evaluation. This review highlights the progress in understanding the role of PI3K/Akt in the development of lung fibrosis and its causative pathological context, including sepsis as well as acute lung injury (ALI) and its consequent acute respiratory distress syndrome (ARDS). We further summarize current knowledge about PI3K inhibitors for pulmonary fibrosis treatment, including drugs under development as well as in clinical trials. We finally discuss how the design of inhaled compounds targeting the PI3K pathways might potentiate efficacy and improve tolerability.

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.

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.

The Interaction Between Pulmonary Fibrosis and COVID-19 and the Application of Related Anti-Fibrotic Drugs

COVID-19 is a highly contagious respiratory disease, which mainly affects the lungs. Critically ill patients are easily complicated by cytokine storms, acute respiratory distress syndrome (ARDS), and respiratory failure, which seriously threaten their lives. Pulmonary fibrosis (PF) is a common interstitial lung disease, and its pathogenesis may involve the participation of a variety of immune cells and inflammatory factors. Current studies have shown that patients with COVID-19 may be complicated by pulmonary fibrosis, and patients with pulmonary fibrosis may also be at higher risk of contracting COVID-19 than healthy people. Pulmonary fibrosis is an important risk factor leading to the aggravation of COVID-19 disease. COVID-19 complicated by cytokine storm and ARDS mechanism pathways are similar to the pathogenesis of pulmonary fibrosis. The potential interaction between pulmonary fibrosis and COVID-19 can cause acute exacerbation of the patient's condition, but the potential mechanism between the two has not been fully elucidated. Most of the drug treatment programs for COVID-19-related pulmonary fibrosis are currently formulated about the relevant guidelines for idiopathic pulmonary fibrosis (IPF), and there is no clear drug treatment program recommendation. This article aims to summarize the relevant mechanism pathways of COVID-19 and pulmonary fibrosis, explore the interrelationships and possible mechanisms, and discuss the value and risks of existing and potential COVID-19-related pulmonary fibrosis treatment drugs, to provide reference for anti-fibrosis treatment for patients.

Targeting PI3K/AKT signaling for treatment of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive fibrotic interstitial pneumonia with unknown causes. The incidence rate increases year by year and the prognosis is poor without cure. Recently, phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PKB/AKT) signaling pathway can be considered as a master regulator for IPF. The contribution of the PI3K/AKT in fibrotic processes is increasingly prominent, with PI3K/AKT inhibitors currently under clinical evaluation in IPF. Therefore, PI3K/AKT represents a critical signaling node during fibrogenesis with potential implications for the development of novel anti-fibrotic strategies. This review epitomizes the progress that is being made in understanding the complex interpretation of the cause of IPF, and demonstrates that PI3K/AKT can directly participate to the greatest extent in the formation of IPF or cooperate with other pathways to promote the development of fibrosis. We further summarize promising PI3K/AKT inhibitors with IPF treatment benefits, including inhibitors in clinical trials and pre-clinical studies and natural products, and discuss how these inhibitors mitigate fibrotic progression to explore possible potential agents, which will help to develop effective treatment strategies for IPF in the near future.

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.

Morin inhibits the transformation of fibroblasts towards myofibroblasts through regulating "PPAR-γ-glutaminolysis-DEPTOR" pathway in pulmonary fibrosis

Morin, a natural flavonoid exists in many foods and dietary plants, owns good bioactivities. Herein, we investigated its effect on pulmonary fibrosis (PF), and further explored the mechanisms. Results showed that morin remarkably improved the pathologic alterations, and inhibited the transformation of fibroblasts towards myofibroblasts in lungs of mice with bleomycin-induced PF as well as TGF-β1 or hypoxia-stimulated NIH-3T3 cells. Mechanistic studies revealed that morin activated peroxisome proliferator activated receptor-gamma (PPAR-γ), and GW9662 or siPPAR-γ significantly weakened the inhibition of morin on the transformation of NIH-3T3 cells. Furthermore, morin restricted glutaminolysis by down-regulating the level of glutaminase 1 (GLS1), which was confirmed by glutamine deprivation, and GLS1 overexpression. Replenishment of metabolite α-ketoglutarate (α-KG) and 2-hydroxyglutarate (2-HG) inhibited morin-prevented transformation of fibroblasts, but neither TGF-β1 nor hypoxia could induce the transformation of IDH2-knockdown fibroblasts, suggesting 2-HG was directly involved in the action of morin. Then, ubiquitination of DEPTOR was demonstrated to be prevented by morin, which was attributed to KDM4A, an enzyme inactivated by 2-HG, and leucine as well as KDM4A inhibitor obstructed the effect of morin. Finally, the mechanisms of morin were further confirmed in vivo. Collectively, morin inhibited PF through intervening in "PPAR-γ-glutaminolysis-DEPTOR" signals, and subsequent restriction on the transformation of fibroblasts towards myofibroblasts.

Microtubules as Major Regulators of Endothelial Function: Implication for Lung Injury

Endothelial dysfunction has been attributed as one of the major complications in COVID-19 patients, a global pandemic that has already caused over 4 million deaths worldwide. The dysfunction of endothelial barrier is characterized by an increase in endothelial permeability and inflammatory responses, and has even broader implications in the pathogenesis of acute respiratory syndromes such as ARDS, sepsis and chronic illnesses represented by pulmonary arterial hypertension and interstitial lung disease. The structural integrity of endothelial barrier is maintained by cytoskeleton elements, cell-substrate focal adhesion and adhesive cell junctions. Agonist-mediated changes in endothelial permeability are directly associated with reorganization of actomyosin cytoskeleton leading to cell contraction and opening of intercellular gaps or enhancement of cortical actin cytoskeleton associated with strengthening of endothelial barrier. The role of actin cytoskeleton remodeling in endothelial barrier regulation has taken the central stage, but the impact of microtubules in this process remains less explored and under-appreciated. This review will summarize the current knowledge on the crosstalk between microtubules dynamics and actin cytoskeleton remodeling, describe the signaling mechanisms mediating this crosstalk, discuss epigenetic regulation of microtubules stability and its nexus with endothelial barrier maintenance, and overview a role of microtubules in targeted delivery of signaling molecules regulating endothelial permeability and inflammation.