Phosphatidylinositol-3-kinase/akt regulates bleomycin-induced fibroblast proliferation and collagen production

Changes in PI3K/AKT and NRF2/HO-1 signaling expression and intestinal microbiota in bleomycin-induced pulmonary fibrosis

Pulmonary fibrosis is the outcome of the prolonged interstitial pneumonia, characterized by excessive accumulation of fibroblasts and collagen deposition, leading to its development. This study aimed to study the changes in PI3K/AKT and NRF2/HO-1 signaling expression and intestinal microbiota in a rat model of a novel bleomycin-induced pulmonary fibrosis. The findings of our study showed the model was successfully established. The results showed that the alveolar septum in the model was significantly widened and infiltrated by severe inflammatory cells. Alveolar atrophy occurred due to the formation of multiple inflammatory foci. During this period, fibrous tissue was distributed in strips and patches, primarily around the pulmonary interstitium and bronchus. Moreover, lung damage and fibrosis progressively worsened over time. The mRNA expression of HO-1 and NRF2 in the model decreased while the mRNA expression of HIF-1α, VEGF, PI3K and AKT increased. Furthermore, it was observed to decrease the protein expression of E-cad, HO-1 and NRF2, and increase the protein expression of α-SMA and p-AKT. Additionally, this model leaded to an imbalance in the intestinal microbiota. This study demonstrate that the novel pulmonary fibrosis model activates the NRF2/HO-1 pathway and the PI3K/AKT pathway in rat lung tissues, and leading to intestinal barrier disorder.

Suppression of Ventilation-Induced Diaphragm Fibrosis through the Phosphoinositide 3-Kinase-γ in a Murine Bleomycin-Induced Acute Lung Injury Model

Mechanical ventilation (MV), used in patients with acute lung injury (ALI), induces diaphragmatic myofiber atrophy and contractile inactivity, termed ventilator-induced diaphragm dysfunction. Phosphoinositide 3-kinase-γ (PI3K-γ) is crucial in modulating fibrogenesis during the reparative phase of ALI; however, the mechanisms regulating the interactions among MV, myofiber fibrosis, and PI3K-γ remain unclear. We hypothesized that MV with or without bleomycin treatment would increase diaphragm muscle fibrosis through the PI3K-γ pathway. Five days after receiving a single bolus of 0.075 units of bleomycin intratracheally, C57BL/6 mice were exposed to 6 or 10 mL/kg of MV for 8 h after receiving 5 mg/kg of AS605240 intraperitoneally. In wild-type mice, bleomycin exposure followed by MV 10 mL/kg prompted significant increases in disruptions of diaphragmatic myofibrillar organization, transforming growth factor-β1, oxidative loads, Masson's trichrome staining, extracellular collagen levels, positive staining of α-smooth muscle actin, PI3K-γ expression, and myonuclear apoptosis (p < 0.05). Decreased diaphragm contractility and peroxisome proliferator-activated receptor-γ coactivator-1α levels were also observed (p < 0.05). MV-augmented bleomycin-induced diaphragm fibrosis and myonuclear apoptosis were attenuated in PI3K-γ-deficient mice and through AS605240-induced inhibition of PI3K-γ activity (p < 0.05). MV-augmented diaphragm fibrosis after bleomycin-induced ALI is partially mediated by PI3K-γ. Therapy targeting PI3K-γ may ameliorate MV-associated diaphragm fibrosis.

Ketotifen directly modifies the fibrotic response of human skin fibroblasts

Fibrosis is a destructive, end-stage disease process. In the skin, it is associated with systemic sclerosis and scarring with considerable health burden. Ketotifen is a clinical antihistamine and mast cell stabilizer. Studies have demonstrated mast cell-dependent anti-fibrotic effects of ketotifen but direct effects on fibroblasts have not been determined. Human dermal fibroblasts were treated with pro-fibrotic transforming growth factor-β1 (TGFβ) followed by ketotifen or control treatments to determine direct effects on fibrotic fibroblasts. Ketotifen impaired TGFβ-induced α-smooth muscle actin gene and protein responses and decreased cytoskeletal- and contractility-associated gene responses associated with fibrosis. Ketotifen reduced Yes-associated protein phosphorylation, transcriptional coactivator with PDZ binding motif transcript and protein levels, and phosphorylation of protein kinase B. In a fibroblast-populated collagen gel contraction assay, ketotifen reduced the contractile activity of TGFβ-activated fibroblasts. In a murine model of bleomycin-induced skin fibrosis, collagen density and dermal thickness were significantly decreased in ketotifen-treated mice supporting in vitro findings. These results support a novel, direct anti-fibrotic activity of ketotifen, reducing pro-fibrotic phenotypic changes in fibroblasts and reducing collagen fibres in fibrotic mouse skin. Together, these findings suggest novel therapeutic potential and a novel mechanism of action for ketotifen in the context of fibrosis.

The evolution of in vitro models of lung fibrosis: promising prospects for drug discovery

Lung fibrosis is a complex process, with unknown underlying mechanisms, involving various triggers, diseases and stimuli. Different cell types (epithelial cells, endothelial cells, fibroblasts and macrophages) interact dynamically through multiple signalling pathways, including biochemical/molecular and mechanical signals, such as stiffness, affecting cell function and differentiation. Idiopathic pulmonary fibrosis (IPF) is the most common fibrosing interstitial lung disease (fILD), characterised by a notably high mortality. Unfortunately, effective treatments for advanced fILD, and especially IPF and non-IPF progressive fibrosing phenotype ILD, are still lacking. The development of pharmacological therapies faces challenges due to limited knowledge of fibrosis pathogenesis and the absence of pre-clinical models accurately representing the complex features of the disease. To address these challenges, new model systems have been developed to enhance the translatability of preclinical drug testing and bridge the gap to human clinical trials. The use of two- and three-dimensional in vitro cultures derived from healthy or diseased individuals allows for a better understanding of the underlying mechanisms responsible for lung fibrosis. Additionally, microfluidics systems, which replicate the respiratory system's physiology ex vivo, offer promising opportunities for the development of effective therapies, especially for IPF.

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.

Multi-omics analysis reveals the mechanism of action of ophiopogonin D against pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive lung disease with limited therapeutic strategies. Therefore, there is an urgent need to search for safe and effective drugs to treat this condition. Ophiopogonin D (OP-D), a steroidal saponin compound extracted from ophiopogon, possesses various pharmacological properties, including anti-inflammatory, antioxidant, and antitumor effects. However, the potential pharmacological effect of OP-D on pulmonary fibrosis remains unknown.

PURPOSE

The aim of this study was to investigate whether OP-D can improve pulmonary fibrosis and to explore its mechanism of action.

METHODS

The effect of OP-D on pulmonary fibrosis was investigated in vitro and in vivo using a mouse model of IPF induced by bleomycin and an in vitro model of human embryonic lung fibroblasts induced by transforming growth factor-β1 (TGF-β1). The mechanism of action of OP-D was determined using multi-omics techniques and bioinformatics.

RESULTS

OP-D attenuated epithelial-mesenchymal transition and excessive deposition of extracellular matrix in the lungs, promoted the apoptosis of lung fibroblasts, and blocked the differentiation of lung fibroblasts into myofibroblasts. The multi-omics techniques and bioinformatics analysis revealed that OP-D blocked the AKT/GSK3β pathway, and the combination of a PI3K/AKT inhibitor and OP-D was effective in alleviating pulmonary fibrosis.

CONCLUSION

This study demonstrated for the first time that OP-D can reduce lung inflammation and fibrosis. OP-D is thus a potential new drug for the prevention and treatment of pulmonary fibrosis.

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.

Development of a Silk Fibroin-Small Intestinal Submucosa Small-Diameter Vascular Graft with Sequential VEGF and TGF-β1 Inhibitor Delivery for In Situ Tissue Engineering

Proper endothelialization and limited collagen deposition on the luminal surface after graft implantation plays a crucial role to prevent the occurrence of stenosis. To achieve these conditions, a biodegradable graft with adequate mechanical properties and the ability to sequentially deliver therapeutic agents isfabricated. In this study, a dual-release system is constructed through coaxial electrospinning by incorporating recombinant human vascular endothelial growth factor (VEGF) and transforming growth factor β1 (TGF-β1) inhibitor into silk fibroin (SF) nanofibers to form a bioactive membrane. The functionalized SF membrane as the inner layer of the graft is characterized by the release profile, cell proliferation and protein expression. It presents excellent biocompatibility and biodegradation, facilitating cell attachment, proliferation, and infiltration. The core-shell structure enables rapid VEGF release within 10 days and sustained plasmid delivery for 21 days. A 2.0-mm-diameter vascular graft is fabricated by integrating the SF membrane with decellularized porcine small intestinal submucosa (SIS), aiming to facilitate the integration process under a stable extracellular matrix structure. The bioengineered graft is functionalized with the sequential administration of VEGF and TGF-β1, and with the reinforced and compatible mechanical properties, thereby offers an orchestrated solution for stenosis with potential for in situ vascular tissue engineering applications.

Pharmacotherapy and pulmonary fibrosis risk after SARS-CoV-2 infection: a prospective nationwide cohort study in the United States

Background

Pulmonary fibrosis is characterized by lung parenchymal destruction and can increase morbidity and mortality. Pulmonary fibrosis commonly occurs following hospitalization for SARS-CoV-2 infection. As there are medications that modify pulmonary fibrosis risk, we investigated whether distinct pharmacotherapies (amiodarone, cancer chemotherapy, corticosteroids, and rituximab) are associated with differences in post-COVID-19 pulmonary fibrosis incidence.

Methods

We used the National COVID-19 Cohort Collaboration (N3C) Data Enclave, which aggregates and harmonizes COVID-19 data across the United States, to assess pulmonary fibrosis incidence documented at least 60 days after COVID-19 diagnosis among adults hospitalized between January 1st, 2020 and July 6th, 2022 without pre-existing pulmonary fibrosis. We used propensity scores to match pre-COVID-19 drug-exposed and unexposed cohorts (1:1) based on covariates with known influence on pulmonary fibrosis incidence, and estimated the association of drug exposure with risk for post-COVID-19 pulmonary fibrosis. Sensitivity analyses considered pulmonary fibrosis incidence documented at least 30- or 90-days post-hospitalization and pulmonary fibrosis incidence in the COVID-19-negative N3C population.

Findings

Among 5,923,394 patients with COVID-19, we analyzed 452,951 hospitalized adults, among whom pulmonary fibrosis incidence was 1.1 per 100-person-years. 277,984 hospitalized adults with COVID-19 were included in our primary analysis, among whom all drug exposed cohorts were well-matched to unexposed cohorts (standardized mean differences <0.1). The post-COVID-19 pulmonary fibrosis incidence rate ratio (IRR) was 2.5 (95% CI 1.2-5.1, P = 0.01) for rituximab, 1.6 (95% CI 1.3-2.0, P < 0.0001) for chemotherapy, and 1.2 (95% CI 1.0-1.3, P = 0.02) for corticosteroids. Amiodarone exposure had no significant association with post-COVID-19 pulmonary fibrosis (IRR = 0.8, 95% CI 0.6-1.1, P = 0.24). In sensitivity analyses, pre-COVID-19 corticosteroid use was not consistently associated with post-COVID-19 pulmonary fibrosis. In the COVID-19 negative hospitalized population (n = 1,240,461), pulmonary fibrosis incidence was lower overall (0.6 per 100-person-years) and for patients exposed to all four drugs.

Interpretation

Recent rituximab or cancer chemotherapy before COVID-19 infection in hospitalized patients is associated with increased risk for post-COVID-19 pulmonary fibrosis.

Funding

The analyses described in this publication were conducted with data or tools accessed through the NCATS N3C Data Enclave https://covid.cd2h.org and N3C Attribution & Publication Policy v1.2-2020-08-25b supported by NIHK23HL146942, NIHK08HL150291, NIHK23HL148387, NIHUL1TR002389, NCATSU24 TR002306, and a SECURED grant from the Walder Foundation/Center for Healthcare Delivery Science and Innovation, University of Chicago. WFP received a grant from the Greenwall Foundation. This research was possible because of the patients whose information is included within the data and the organizations (https://ncats.nih.gov/n3c/resources/data-contribution/data-transfer-agreement-signatories) and scientists who have contributed to the on-going development of this community resource (https://doi.org/10.1093/jamia/ocaa196).

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.

An Integrative Multiomics Framework for Identification of Therapeutic Targets in Pulmonary Fibrosis

Pulmonary fibrosis (PF) is a heterogeneous disease with a poor prognosis. Therefore, identifying additional therapeutic modalities is required to improve outcome. However, the lack of biomarkers of disease progression hampers the preclinical to clinical translational process. Here, this work assesses and identifies progressive alterations in pulmonary function, transcriptomics, and metabolomics in the mouse lung at 7, 14, 21, and 28 days after a single dose of oropharyngeal bleomycin. By integrating multi-omics data, this work identifies two central gene subnetworks associated with multiple critical pathological changes in transcriptomics and metabolomics as well as pulmonary function. This work presents a multi-omics-based framework to establish a translational link between the bleomycin-induced PF model in mice and human idiopathic pulmonary fibrosis to identify druggable targets and test therapeutic candidates. This work also indicates peripheral cannabinoid receptor 1 (CB1 R) antagonism as a rational therapeutic target for clinical translation in PF. Mouse Lung Fibrosis Atlas can be accessed freely at https://niaaa.nih.gov/mouselungfibrosisatlas.

Uncovering mechanisms of Baojin Chenfei formula treatment for silicosis by inhibiting inflammation and fibrosis based on serum pharmacochemistry and network analysis

BACKGROUND

Baojin Chenfei formula (BCF), a Chinese herbal formula, has significant effects on improving the clinical symptoms of patients with silicosis. However, its active compounds and the underlying mechanisms have not yet fully been elucidated.

PURPOSE

This study aimed to explore the underlying mechanisms of BCF in treating silicosis.

METHODS

The rat model of silicosis was developed via a single intratracheal instillation of SiO₂ suspension to examine the therapeutic impacts of BCF on silicosis. Subsequently, the active compounds, targets, and mechanisms of BCF were analyzed based on serum pharmacochemistry and network analysis. Finally, the underlying mechanisms of representative compounds of BCF were validated in vitro experiments.

RESULTS

BCF significantly alleviated SiO₂-induced silicosis in rats, evidenced by improved lung function, decreased pathological injury, and reduced inflammatory response and fibrosis. 19 active compounds were identified from the rat serum samples after BCF gavage. Subsequently, 299 targets for these 19 compounds in BCF and 257 genes related to silicosis were collected. 26 overlapping targets, including AKT1, TNF, IL6, MAPK3, EGFR, and others, were obtained from the intersection of the 299 BCF-related targets and 257 silicosis-associated genes. These overlapping targets mainly corresponded to glycyrrhetic acid and paeoniflorin and were mainly associated with positive regulation of smooth muscle cell proliferation, positive regulation of MAP kinase activity, and inflammatory response. In vitro experiments also demonstrated that the representative compounds of BCF (glycyrrhetic acid and paeoniflorin) could suppress inflammatory response by the MAPK pathway, and also inhibited fibroblast activation by the EGFR-PI3K-AKT pathway.

CONCLUSION

Active compounds of BCF, such as glycyrrhetic acid and paeoniflorin, could suppress inflammatory response by the MAPK pathway and suppress fibroblast activation by the EGFR-PI3K-AKT pathway. These might be the mechanisms of BCF in treating silicosis.

Oxymatrine inhibits TGF‑β1‑mediated mitochondrial apoptotic signaling in alveolar epithelial cells via activation of PI3K/AKT signaling

Although pulmonary fibrosis (PF) causes respiratory failure and death, effective therapies for PF have not been developed. Oxymatrine (OMT), an active ingredient in the Chinese herb Sophora flavescens, exerts antifibrotic effects; however, its effect on PF remains unclear. The present study aimed to determine whether OMT decreases transforming growth factor-β1 (TGF-β1)-induced PF in human lung cancer A549 cells by inhibiting apoptosis and targeting the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) pathway. To construct a PF cell model, A549 cells were stimulated with TGF-β1. The experimental groups were as follows: control (untreated cells grown in complete medium), TGF-β1 (cells treated with 5 ng/ml TGF-β1), OMT (cells treated with 5 ng/ml TGF-β1 and 0.25, 0.50, or 1.00 mg/ml OMT), and OMT + LY294002 (cells treated with 5 ng/ml TGF-β1, 1.0 mg/ml OMT. and 25 µmol/l LY294002). The effects of OMT on cell morphology (via electron microscopy), apoptosis (via Annexin V-PI staining), mitochondrial apoptosis signaling [using JC-1 method to analyze mitochondrial membrane potential (MMP)], and Bcl-2, as well as Bax expression (via western blotting and reverse transcription-quantitative polymerase chain reaction), were analyzed. OMT significantly protected cells against TGF-β1-induced PF by inhibiting apoptosis. The specific manifestations were cell injury, as evidenced by morphological changes and decreased MMP. Following OMT treatment, the expression of the pro-apoptotic protein Bax increased, whereas that of the anti-apoptotic protein Bcl-2 decreased. The PI3K/AKT-specific inhibitor LY294002 significantly inhibited the ameliorative effects of OMT on TGF-β1-induced apoptosis. Collectively, OMT attenuated TGF-β1-mediated mitochondrial apoptosis of alveolar epithelial cells by activating the PI3K/AKT signaling pathway. Therefore, OMT may be a promising drug for PF treatment.

Attenuation of Ventilation-Enhanced Epithelial–Mesenchymal Transition through the Phosphoinositide 3-Kinase-γ in a Murine Bleomycin-Induced Acute Lung Injury Model

Mechanical ventilation (MV) used in patients with acute lung injury (ALI) induces lung inflammation and causes fibroblast proliferation and excessive collagen deposition—a process termed epithelial–mesenchymal transition (EMT). Phosphoinositide 3-kinase-γ (PI3K-γ) is crucial in modulating EMT during the reparative phase of ALI; however, the mechanisms regulating the interactions among MV, EMT, and PI3K-γ remain unclear. We hypothesized that MV with or without bleomycin treatment would increase EMT through the PI3K-γ pathway. C57BL/6 mice, either wild-type or PI3K-γ-deficient, were exposed to 6 or 30 mL/kg MV for 5 h after receiving 5 mg/kg AS605240 intraperitoneally 5 days after bleomycin administration. We found that, after bleomycin exposure in wild-type mice, high-tidal-volume MV induced substantial increases in inflammatory cytokine production, oxidative loads, Masson’s trichrome staining level, positive staining of α-smooth muscle actin, PI3K-γ expression, and bronchial epithelial apoptosis (p < 0.05). Decreased respiratory function, antioxidants, and staining of the epithelial marker Zonula occludens-1 were also observed (p < 0.05). MV-augmented bleomycin-induced pulmonary fibrogenesis and epithelial apoptosis were attenuated in PI3K-γ-deficient mice, and we found pharmacological inhibition of PI3K-γ activity through AS605240 (p < 0.05). Our data suggest that MV augmented EMT after bleomycin-induced ALI, partially through the PI3K-γ pathway. Therapy targeting PI3K-γ may ameliorate MV-associated EMT.

Stability and Activity of Interferon Beta to Treat Idiopathic Pulmonary Fibrosis with Different Nebulizer Technologies

Background: Idiopathic pulmonary fibrosis (IPF) is a serious lung disease characterized by lung scarring, which results in breathing difficulty. Currently, patients with IPF exhibit a poor survival rate and have access to very limited therapeutic options. Interferon beta (IFN-β) has been approved by the U.S. Food and Drug Administration (FDA) for the treatment of relapsing forms of multiple sclerosis, and it has also been shown to exhibit therapeutic potential in IPF. However, clinical use of IFN-β did not lead to improved overall survival in IPF patients in existing studies. One possibility is the limited efficiency of IFN-β delivery through intravenous or subcutaneous injection. Materials and Methods: The aerosol particle size distribution was determined with a laser diffraction particle size analyzer to characterize the droplet size and fine particle fraction generated by three types of nebulizers: jet, ultrasonic, and mesh. A breathing simulator was used to assess the delivery efficiency of IFN-β, and the temperature in the medication reservoirs was monitored with a thermocouple during nebulization. To further evaluate the antifibrotic activity of IFN-β pre- and postnebulization, bleomycin (BLM)- or transforming growth factor-beta (TGF-β)-treated human lung fibroblast (HLF) cells were used. Cell viability was measured by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Transwell migration assay and Q-PCR analysis were used to evaluate cell migration and the myofibroblast differentiation ability, respectively. IFN-β protein samples were prepared using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) sample loading buffer, and the expression of IFN-β was assessed by western blotting. Results: Among the current drug delivery systems, aerosolized medication has shown increased efficacy of drug delivery for treating respiratory diseases when compared with parenteral drugs. It was found that neither the structural integrity nor the biological function of nebulized IFN-β was compromised by the nebulization process of the mesh nebulizer. In addition, in BLM dose-response or TGF-β-induced lung fibroblast proliferation assays, these effects could be reversed by both parenteral and inhaled IFN-β nebulized with the mesh nebulizer. Nebulized IFN-β with the mesh nebulizer also significantly inhibited the migration and myofibroblast differentiation ability of TGF-β-treated HLF cells. Conclusions: The investigations revealed the potential efficacy of IFN-β in the treatment of IPF with the mesh nebulizer, demonstrating the higher efficiency of IFN-β delivered through the mesh nebulizer.

Yangqing Chenfei formula attenuates silica-induced pulmonary fibrosis by suppressing activation of fibroblast via regulating PI3K/AKT, JAK/STAT, and Wnt signaling pathway

BACKGROUND

Yangqing Chenfei formula (YCF) has been demonstrated its clinical efficiency on silicosis patients. However, the effect of YCF against silicotic fibrosis and its mechanism remain unclear.

PURPOSE

This study is aimed to investigate active compounds and molecular mechanism of YCF in treating silicosis.

METHOD

YCF was orally administrated to silicosis rats induced by crystalline silica. The effective fraction of YCF and the compounds was isolated and identified by using macroporous resin and HPLC-MS, respectively. The targets and potential molecular mechanism of YCF against silicotic fibrosis were investigated through pharmacological network and RNA-sequencing analysis and in vitro-experimental validation.

RESULTS

YCF could remarkably improve the lung function and pathological changes of silicotic rats, reduce the aggregation of fibrocytes and deposition of ECM, such as collagen I, III, FN, and α-SMA, and suppress the TGF-β/Smad3 signaling. Furthermore, YCF6, the effective fraction derived from YCF, could significantly inhibit fibroblast activation induced by TGF-β. Then, 135 compounds were identified from YCF6 by using HPLC-MS, and Network pharmacology analysis predicted total 941 targets for these compounds. Moreover, 409 differentially expressed genes of fibroblast activation induced by TGF-β were identified. Then, integrated analysis of the 941 targets with 409 differentially expressed genes showed that YCF6 contains multiple compounds, such as tangeretin, L-Malic acid, 2-Monolinolein etc., which inhibits fibroblast activation probably by targeting different proteins, such as PIK3CA, AKT1, JAK2, STAT3, GSK3β, leading to regulate the signal network, such as PI3K/AKT signaling pathway, JAK/STAT signaling pathway, and Wnt signaling pathway. Finally, in vitro experiment indicated that tangeretin, the active compound contained in YCF6, could significantly inhibit TGF-β induced fibroblast activation. Moreover, YCF6 and tangeretin could markedly inhibit the activation of PI3K/AKT, JAK/STAT, and Wnt pathway.

CONCLUSION

YCF contained multiple compounds and targeted various proteins that regulated the fibroblast activation, which might be the molecular mechanisms of it in treating silicosis.

Thymol protects against bleomycin-induced pulmonary fibrosis via abrogation of oxidative stress, inflammation, and modulation of miR-29a/TGF-β and PI3K/Akt signaling in mice

Idiopathic pulmonary fibrosis is a terminal lung ailment that shares several pathological and genetic mechanisms with severe COVID-19. Thymol (THY) is a dietary compound found in thyme species that showed therapeutic effects against various diseases. However, the effect of THY against bleomycin (BLM)-induced lung fibrosis was not previously investigated. The current study investigated the ability of THY to modulate oxidative stress, inflammation, miR-29a/TGF-β expression, and PI3K/phospho-Akt signaling in lung fibrosis. Mice were divided into Normal, THY (100 mg/kg, p.o.), BLM (15 mg/kg, i.p.), BLM + THY (50 mg/kg, p.o.), and BLM + THY (100 mg/kg, p.o.) groups and treated for four weeks. The obtained results showed that BLM + THY (50 mg/kg) and BLM + THY (100 mg/kg) reduced fibrotic markers; α-SMA and fibronectin, inflammatory mediators; TNF-α, IL-1β, IL-6, and NF-kB and oxidative stress biomarkers; MDA, GSH, and SOD, relative to BLM group. Lung histopathological examination by H&E and Masson's trichrome stains confirmed the obtained results. Remarkably, expression levels of TGF-β, PI3K, and phospho-Akt were decreased while miR-29a expression was elevated. In conclusion, THY effectively prevented BLM-induced pulmonary fibrosis by exerting significant anti-oxidant and anti-inflammatory effects. Our novel findings that THY upregulated lung miR-29a expression while decreased TGF-β and PI3K/Akt signaling are worthy of further investigation as a possible molecular mechanism for THY's anti-fibrotic actions.

Molecular mechanisms of alveolar epithelial cell senescence and idiopathic pulmonary fibrosis: a narrative review

Background and Objective

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive interstitial pneumonia of unknown etiology. An increasing number of studies have reported that the incidence of IPF increases with age. Simultaneously, the number of senescent cells increased in IPF. Epithelial cell senescence, an important component of epithelial cell dysfunction, plays a key role in IPF pathogenesis. This article summarizes the molecular mechanisms associated with alveolar epithelial cell senescence and recent advances in the applications of drugs targeting pulmonary epithelial cell senescence to explore novel therapeutic approaches for the treatment of pulmonary fibrosis.

Methods

All literature published in English on PubMed, Web of Science, and Google Scholar were electronically searched online using the following keyword combinations: aging, alveolar epithelial cell, cell senescence, idiopathic pulmonary fibrosis, WNT/β-catenin, phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt), mammalian target of rapamycin (mTOR), and nuclear factor kappa B (NF-κB).

Key Content and Findings

We focused on signaling pathways associated with alveolar epithelial cell senescence in IPF, including WNT/β-catenin, PI3K/Akt, NF-κB, and mTOR signaling pathways. Some of these signaling pathways are involved in alveolar epithelial cell senescence by affecting cell cycle arrest and secretion of senescence-associated secretory phenotype-associated markers. We also found that changes in lipid metabolism in alveolar epithelial cells can be induced by mitochondrial dysfunction, both of which contribute to cellular senescence and development of IPF.

Conclusions

Decreasing senescent alveolar epithelial cells may be a promising strategy for the treatment of IPF. Therefore, further investigations into new treatments of IPF by applying inhibitors of relevant signaling pathways, as well as senolytic drugs, are warranted.

Growth Factor Binding Peptides in Poly (Ethylene Glycol) Diacrylate (PEGDA)-Based Hydrogels for an Improved Healing Response of Human Dermal Fibroblasts

Growth factors (GF) are critical cytokines in wound healing. However, the direct delivery of these biochemical cues into a wound site significantly increases the cost of wound dressings and can lead to a strong immunological response due to the introduction of a foreign source of GFs. To overcome this challenge, we designed a poly(ethylene glycol) diacrylate (PEGDA) hydrogel with the potential capacity to sequester autologous GFs directly from the wound site. We demonstrated that synthetic peptide sequences covalently tethered to PEGDA hydrogels physically retained human transforming growth factor beta 1 (hTGFβ1) and human vascular endothelial growth factor (hVEGF) at 3.2 and 0.6 ng/mm², respectively. In addition, we demonstrated that retained hTGFβ1 and hVEGF enhanced human dermal fibroblasts (HDFa) average cell surface area and proliferation, respectively, and that exposure to both GFs resulted in up to 1.9-fold higher fraction of area covered relative to the control. After five days in culture, relative to the control surface, non-covalently bound hTGFβ1 significantly increased the expression of collagen type I and hTGFβ1 and downregulated vimentin and matrix metalloproteinase 1 expression. Cumulatively, the response of HDFa to hTGFβ1 aligns well with the expected response of fibroblasts during the early stages of wound healing.

The Role of DNA Damage and Repair in Idiopathic Pulmonary Fibrosis

The mortality rate of idiopathic pulmonary fibrosis (IPF) increases yearly due to ineffective treatment. Given that the lung is exposed to the external environment, it is likely that oxidative stress, especially the stimulation of DNA, would be of particular importance in pulmonary fibrosis. DNA damage is known to play an important role in idiopathic pulmonary fibrosis initiation, so DNA repair systems targeting damage are also crucial for the survival of lung cells. Although many contemporary reports have summarized the role of individual DNA damage and repair pathways in their hypotheses, they have not focused on idiopathic pulmonary fibrosis. This review, therefore, aims to provide a concise overview for researchers to understand the pathways of DNA damage and repair and their roles in IPF.

A Promising Candidate in Tendon Healing Events—PDGF-BB

Tendon injuries are one of the most common musculoskeletal disorders for which patients seek medical aid, reducing not only the quality of life of the patient but also imposing a significant economic burden on society. The administration of growth factors at the wound site is a feasible solution for enhancing tendon healing. Platelet-derived growth factor-BB (PDGF-BB) has a well-defined safety profile compared to other growth factors and has been approved by the Food and Drug Administration (FDA). The purpose of this review is to summarize the role of PDGF-BB in tendon healing through a comprehensive review of the published literature. Experimental studies suggest that PDGF-BB has a positive effect on tendon healing by enhancing inflammatory responses, speeding up angiogenesis, stimulating tendon cell proliferation, increasing collagen synthesis and increasing the biomechanics of the repaired tendon. PDGF-BB is regarded as a promising candidate in tendon healing. However, in order to realize its full potential, we still need to carefully consider and study key issues such as dose and application time in the future, so as to explore further applications of PDGF-BB in the tendon healing process.

The Pro-Fibrotic Response to Lens Injury Is Signaled in a PI3K Isoform-Specific Manner

The signaling inputs that function to integrate biochemical and mechanical cues from the extracellular environment to alter the wound-repair outcome to a fibrotic response remain poorly understood. Here, using a clinically relevant post-cataract surgery wound healing/fibrosis model, we investigated the role of Phosphoinositide-3-kinase (PI3K) class I isoforms as potential signaling integrators to promote the proliferation, emergence and persistence of collagen I-producing alpha smooth muscle actin (αSMA+) myofibroblasts that cause organ fibrosis. Using PI3K isoform specific small molecule inhibitors, our studies revealed a requisite role for PI3K p110α in signaling the CD44+ mesenchymal leader cell population that we previously identified as resident immune cells to produce and organize a fibronectin-EDA rich provisional matrix and transition to collagen I-producing αSMA+ myofibroblasts. While the PI3K effector Akt was alone insufficient to regulate myofibroblast differentiation, our studies revealed a role for Rac, another potential PI3K effector, in this process. Our studies further uncovered a critical role for PI3K p110α in signaling the proliferation of CD44+ leader cells, which is important to the emergence and expansion of myofibroblasts. Thus, these studies identify activation of PI3K p110α as a critical signaling input following wounding to the development and progression of fibrotic disease.

Modeling Kaempferol as a Potential Pharmacological Agent for COVID-19/PF Co-Occurrence Based on Bioinformatics and System Pharmacological Tools

Objective: People suffering from coronavirus disease 2019 (COVID-19) are prone to develop pulmonary fibrosis (PF), but there is currently no definitive treatment for COVID-19/PF co-occurrence. Kaempferol with promising antiviral and anti-fibrotic effects is expected to become a potential treatment for COVID-19 and PF comorbidities. Therefore, this study explored the targets and molecular mechanisms of kaempferol against COVID-19/PF co-occurrence by bioinformatics and network pharmacology.

Methods: Various open-source databases and Venn Diagram tool were applied to confirm the targets of kaempferol against COVID-19/PF co-occurrence. Protein-protein interaction (PPI), MCODE, key transcription factors, tissue-specific enrichment, molecular docking, Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were used to clarify the influential molecular mechanisms of kaempferol against COVID-19 and PF comorbidities.

Results: 290 targets and 203 transcription factors of kaempferol against COVID-19/PF co-occurrence were captured. Epidermal growth factor receptor (EGFR), proto-oncogene tyrosine-protein kinase SRC (SRC), mitogen-activated protein kinase 3 (MAPK3), mitogen-activated protein kinase 1 (MAPK1), mitogen-activated protein kinase 8 (MAPK8), RAC-alpha serine/threonine-protein kinase (AKT1), transcription factor p65 (RELA) and phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit alpha isoform (PIK3CA) were identified as the most critical targets, and kaempferol showed effective binding activities with the above critical eight targets. Further, anti-COVID-19/PF co-occurrence effects of kaempferol were associated with the regulation of inflammation, oxidative stress, immunity, virus infection, cell growth process and metabolism. EGFR, interleukin 17 (IL-17), tumor necrosis factor (TNF), hypoxia inducible factor 1 (HIF-1), phosphoinositide 3-kinase/AKT serine/threonine kinase (PI3K/AKT) and Toll-like receptor signaling pathways were identified as the key anti-COVID-19/PF co-occurrence pathways.

Conclusion: Kaempferol is a candidate treatment for COVID-19/PF co-occurrence. The underlying mechanisms may be related to the regulation of critical targets (EGFR, SRC, MAPK3, MAPK1, MAPK8, AKT1, RELA, PIK3CA and so on) and EGFR, IL-17, TNF, HIF-1, PI3K/AKT and Toll-like receptor signaling pathways. This study contributes to guiding development of new drugs for COVID-19 and PF comorbidities.

Investigation of the Pharmacological Effect and Mechanism of Jinbei Oral Liquid in the Treatment of Idiopathic Pulmonary Fibrosis Using Network Pharmacology and Experimental Validation

Overview: Idiopathic pulmonary fibrosis (IPF) is a disease caused by many factors, eventually resulting in lung function failure. Jinbei oral liquid (JBOL) is a traditional Chinese clinical medicine used to treat pulmonary diseases. However, the pharmacological effects and mechanism of the action of JBOL on IPF remain unclear. This study investigated the protective effects and mechanism of the action of JBOL on IPF using network pharmacology analysis, followed by in vivo and in vitro experimental validation.

Methods: The components of JBOL and their targets were screened using the TCMSP database. IPF-associated genes were obtained using DisGeNET and Drugbank. The common targets of JBOL and IPF were identified with the STRING database, and a protein–protein interaction (PPI) network was constructed. GO and KEGG analyses were performed. Sprague–Dawley rats were injected with bleomycin (BLM) to establish an IPF model and treated orally with JBOL at doses of 5.4, 10.8, and 21.6 ml/kg. A dose of 54 mg/kg of pirfenidone was used as a control. All rats were treated for 28 successive days. Dynamic pulmonary compliance (Cdyn), minute ventilation volume (MVV), vital capacity (VC), and lung resistance (LR) were used to evaluate the efficacy of JBOL. TGF-β–treated A549 cells were exposed to JBOL, and epithelial-to-mesenchymal transition (EMT) changes were assessed. Western blots were performed.

Results: Two hundred seventy-eight compounds and 374 targets were screened, and 103 targets related to IPF were identified. Core targets, including MAPK1 (ERK2), MAPK14 (p38), JUN, IL-6, AKT, and others, were identified by constructing a PPI network. Several pathways were involved, including the MAPK pathway. Experimentally, JBOL increased the levels of the pulmonary function indices (Cdyn, MVV, and VC) in a dose-dependent manner and reduced the RL level in the BLM-treated rats. JBOL increased the epithelial marker E-cadherin and suppressed the mesenchymal marker vimentin expression in the TGF-β–treated A549 cells. The suppression of ERK1/2, JNK, and p38 phosphorylation by JBOL was validated.

Conclusion: JBOL had therapeutic effects against IPF by regulating pulmonary function and EMT through a systemic network mechanism, thus supporting the need for future clinical trials of JBOL.

Syringic and ascorbic acids prevent NDMA-induced pulmonary fibrogenesis, inflammation, apoptosis, and oxidative stress through the regulation of PI3K-Akt/PKB-mTOR-PTEN signaling pathway

Idiopathic lung fibrosis (ILF) is a severe and life threatening lung disorder that is characterized by scarring of lung tissue, leading to thickening and stiffening of affected areas. This study looked at the role played by PI3K-Akt/PKB-mToR signaling pathway in the pathogenesis of N-Nitrosodimethylamine (NDMA)-induced lung fibrotic injury, and the effects of syringic acid (SYR) and ascorbic acid (ASC) treatments in male Wistar rats. Pulmonary fibrosis was induced by intraperitoneal injection of 10 mg/kg NDMA once daily, thrice (consecutively) a week for four weeks, and this condition was treated daily with SYR (50 mg/kg) and ASC (100 mg/kg) acids orally for four weeks. Fibrogenesis, following NDMA administration was marked by a significant increase in collagen-1 and α-SMA levels, while oxidative stress was marked by a significant decrease in GSH level, GST, GPx, CAT, and SOD activities. Also, NDMA significantly increased lung Bax, p53, caspase-3, TNF-α, IL-1β, NFkB, and decreased Bcl-2, mdm2, cyclin D1 and Nrf-2 levels. Looking at the PI3K-Akt-mTOR signaling pathway, NDMA administration significantly activated lung PI3K, Akt, and mTOR, and deactivated PTEN, FoxO1 and TSC2. Treatments with SYR and ASC significantly reduced oxidative stress by restoring the antioxidant systems via Nrf2 activation, decreased the levels of inflammatory markers through inhibition of NFkB, downregulated p53, Bax, and caspase-3 via up-regulation of mdm2 and cyclin D1. SYR and ASC also regulated the PI3K-Akt-mTOR signaling pathway via the deactivation of PI3K, Akt, and mTOR, and up-regulation of PTEN, FoxO1 and TSC2. Overall, SYR and ASC modulate the PI3K-Akt-mTOR signaling pathway via inhibition of oxidative stress, inflammation and apoptosis in NDMA-induced lung fibrosis.

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.

Targeting Type I Collagen for Cancer Treatment

Collagen is the most abundant protein in animals. Interactions between tumor cells and collagen influence every step of tumor development. Type I collagen is the main fibrillar collagen in the extracellular matrix and is frequently up-regulated during tumorigenesis. The binding of type I collagen to its receptors on tumor cells promotes tumor cell proliferation, epithelial-mesenchymal transition, and metastasis. Type I collagen also regulates the efficacy of tumor therapies, such as chemotherapy, radiotherapy, and immunotherapy. Furthermore, type I collagen fragments are diagnostic markers of metastatic tumors and have prognostic value. Inhibition of type I collagen synthesis has been reported to have anti-tumor effects in animal models. However, collagen has also been shown to possess anti-tumor activity. Therefore, the roles that type I collagen plays in tumor biology are complex and tumor type-dependent. In this review, we discuss the expression and regulation of synthesis of type I collagen, as well as the role up-regulated type I collagen plays in various stages of cancer progression. We also discuss the role of collagen in tumor therapy. Finally, we highlight several recent approaches targeting type I collagen for cancer treatment. This article is protected by copyright. All rights reserved.

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.

Iron overload and mitochondrial dysfunction orchestrate pulmonary fibrosis

Pulmonary fibrosis (PF) is a chronic, progressive heterogeneous disease of lung tissues with poor lung function caused by scar tissue. Due to our limited understanding of its mechanism, there is currently no treatment strategy that can prevent the development of PF. In recent years, iron accumulation and mitochondrial damage have been reported to participate in PF, and drugs that reduce iron content and improve mitochondrial function have shown significant efficacy in animal experimental models. Excessive iron leads to mitochondrial impairment, which may be the key cause that results in the dysfunction of various kinds of pulmonary cells and further promotes PF. As an emerging research hotspot, there are few targeted effective therapeutic strategies at present due to limited mechanistic understanding. In this review, the roles of iron homeostasis imbalance and mitochondrial damage in PF are summarized and discussed, highlighting a promising direction for finding truly effective therapeutics for PF.

Diversity among differentially expressed genes in atrial appendages of atrial fibrillation: The role and mechanism of SPP1 in atrial fibrosis

BACKGROUND

Structural remodeling plays an important role in the occurrence and maintenance of atrial fibrillation (AF), but the mechanism is currently unclear. This study was designed to investigate the transcriptomic mechanism of structural remodeling of AF through bioinformatic analysis and in vivo and vitro experiments.

METHODS

Transcriptomic datasets were retrieved from the Gene Expression Omnibus (GEO) database, and bioinformatics analysis was performed to screen mRNAs associated with AF. Cell and animal models were constructed to verify the bioinformatic findings using RT-qPCR and western blot analysis. Then, SPP1 was screened as the target gene, and the mechanism by which it promotes fibrosis was further studied in human cardiac fibroblasts (HCFs) using western blot analysis.

RESULTS

After retrieval, the GSE14975, GSE31821, GSE79768, GSE115574 and GSE128188 datasets were used in this study. In total, 147 differentially expressed genes (DEGs) were identified in left atrial appendix tissue and 85 in right atrial appendix tissue. According to the enrichment analysis results, the calcium signaling pathway was found to play an important role in AF, in which EGFR, AGTR1, HTR2B, CD38 and BDKRB1 might be the key genes. Moreover, SPP1 was identified as a key driver through PPI analysis and experimentally proved to reduce the expression of p27 by regulating the PI3K/Akt signaling pathway, sequentially promoting HCF fibrosis.

CONCLUSION

Bioinformatics analysis showed that the calcium signaling pathway might play an important role in AF, while SPP1 could promote myocardial fibrosis through the PI3K/Akt/p27 signaling axis.

Evaluating the Therapeutic Mechanisms of Selected Active Compounds in Houttuynia cordata Thunb. in Pulmonary Fibrosis via Network Pharmacology Analysis

Pulmonary fibrosis, a common outcome of pulmonary interstitial disease of various different etiologies, is one of the most important causes of respiratory failure. Houttuynia cordata Thunb. (family: Saururaceae) (H. cordata), as has been reported, is a Chinese herbal medicine commonly used to treat upper respiratory tract infection and bronchitis. Our previous study has proven that sodium houttuyfonate (an additional compound from sodium bisulfite and houttuynin) had beneficial effects in the prevention of pulmonary fibrosis (PF) induced by bleomycin (BLM) in mice. In the present study, network pharmacology was used to investigate the efficiency and potential mechanisms of H. cordata in PF treatment. Upon manual collection from the literature and databases such as TCMSP and TCM-ID, 10 known representative ingredients of H. cordata species were screened. Then, the prediction of the potential active ingredients, action targets, and signaling pathways were conducted through the Gene Ontology (GO), protein–protein interaction (PPI),and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. The results of network pharmacology prediction suggested that H. cordata may act through multiple signaling pathways to alleviate PF, including the phosphatidylinositol 3-kinase-protein kinase B (PI3K/AKT) pathways, mitogen-activated protein kinase (MAPK) pathways, the tumor necrosis factor (TNF) pathways, and interleukin-17 (IL-17) signaling pathways. Molecular docking experiments showed that the chemical constituents of H. cordata had good affinity with TNF, MAPK1, and AKT1, and using lipopolysaccharide (LPS)-induced A549 cells, a model was established to verify the anti-pulmonary fibrosis effects and related mechanisms of H. cordata–relevant constituents. Finally, these evidences collectively suggest H. cordata may alleviate PF progression via PI3K/Akt, MAPK, and TNF signaling pathways and provide novel insights to verify the mechanism of H. cordata in the treatment of PF.

Dynamic Observation of Autophagy and Transcriptome Profiles in a Mouse Model of Bleomycin-Induced Pulmonary Fibrosis

Pulmonary fibrosis is a group of progressive, fibrotic, and fatal lung diseases, and the role of autophagy in pulmonary fibrosis is controversial. In the current research, we dynamically observed a bleomycin-induced pulmonary fibrosis mouse model after 3, 7, 14, 21, and 28 days and investigated the expression of autophagy markers. We found that autophagy markers were not significantly changed on the indicated days in the mouse lung tissue. Then, RNA-Seq was used to analyze the gene expression and associated functions and pathways in fibrotic lung tissue on different days post-bleomycin. In addition, short time series expression miner (STEM) analysis was performed to explore the temporal post-bleomycin gene expression. Through STEM, continually up- or downregulated profiles did not demonstrate the critical role of autophagy in the development of fibrosis. Furthermore, gene ontology (GO) annotations showed that continually upregulated profiles were mainly related to fibrosis synthesis, extracellular space, and inflammation, while enriched pathways were mainly related to the PI3K-Akt signaling pathway, ECM-receptor interactions, and focal adhesion signaling pathway. For continually downregulated profiles, GO annotations mainly involved sarcomere organization, muscle contraction, and muscle fiber development. The enriched KEGG signaling pathways were the cAMP signaling pathway, cGMP-PKG signaling pathway, calcium signaling pathway, and cardiac muscle contraction. Moreover, we analyzed autophagy-related genes' expression in specific cells from a publicly available database of three human and one animal study of pulmonary fibrosis using single-cell sequencing technology. All results consistently demonstrated no critical role of autophagy in the pathogenesis of pulmonary fibrosis. In summary, autophagy may not critically and consistently change during the development of pulmonary fibrosis at different stages post-bleomycin in a mouse model. These continually up- or downregulated profiles, including gene profiles, and the corresponding functions and pathways may provide mechanistic insights into IPF therapy.

The evaluation of functional small intestinal submucosa for abdominal wall defect repair in a rat model: Potent effect of sequential release of VEGF and TGF-β1 on host integration

Ineffective vessel penetration and extracellular matrix (ECM) remodeling are responsible for the failure of porcine small intestinal submucosa (SIS)-repaired abdominal wall defects. Combined growth factors could be used as directing signals in a nature-mimicking strategy to improve this repair through mesh functionalization. In this work, vascular endothelial growth factor (VEGF) and transforming growth factor β1 (TGF-β1) were incorporated into a silk fibroin membrane via coaxial aqueous electrospinning to exploit their benefits of biological interactions. The membrane was sandwiched into the SIS bilayer as a functional mesh to repair partial-thickness defects in a rat model. Membrane characterization demonstrated that the core-shell structure ensured the independent distribution and sequential release of two regulators and protection of their bioactivities, which were confirmed by cell viability and protein expression. The mesh was further assessed to facilitate vasculature formation and collagen secretion in vitro, and exhibited better host integration than VEGF- or TGF-β1-containing mesh and developed reinforced mechanical properties compared with the VEGF-containing mesh after 28 days in vivo. Determination of the underlying biological interactions revealed that rapid VEGF release promotes angiogenesis and collagen secretion but initially potentiates the inflammatory response. Sustained TGF-β1 release at relatively low concentrations promoted VEGF for vessel permeation and maturation and steadily induced ECM remodeling under milder foreign body reactions. The functionalization of SIS improves repair by sufficient integration with timely remodeling and helps elucidate the related regulatory interactions.

Tauroursodeoxycholic acid alleviates pulmonary endoplasmic reticulum stress and epithelial-mesenchymal transition in bleomycin-induced lung fibrosis

Background

Several studies demonstrate that endoplasmic reticulum (ER) stress-mediated epithelial-mesenchymal transition (EMT) is involved in the process of bleomycin (BLM)-induced pulmonary fibrosis. Tauroursodeoxycholic acid (TUDCA), a bile acid with chaperone properties, is an inhibitor of ER stress. This study aimed to investigate the preventive effects of TUDCA on BLM-induced EMT and lung fibrosis.

Methods

The model of lung fibrosis was established by intratracheal injection with a single dose of BLM (3.0 mg/kg). In TUDCA + BLM group, mice were intraperitoneally injected with TUDCA (250 mg/kg) daily.

Results

BLM-induced alveolar septal destruction and inflammatory cell infiltration were alleviated by TUDCA. BLM-induced interstitial collagen deposition, as determined by Sirius Red staining, was attenuated by TUDCA. BLM-induced elevation of pulmonary α-smooth muscle actin (α-SMA) and reduction of pulmonary E-cadherin were attenuated by TUDCA. BLM-induced pulmonary Smad2/3 phosphorylation was suppressed by TUDCA. BLM-induced elevation of Ki67 and PCNA was inhibited by TUDCA in mice lungs. In addition, BLM-induced elevation of HO-1 (heme oxygenase-1) and 3-NT (3-nitrotyrosine) was alleviated by TUDCA. Finally, BLM-induced upregulation of pulmonary GRP78 and CHOP was attenuated by TUDCA.

Conclusions

These results provide evidence that TUDCA pretreatment inhibits Smad2/3-medited EMT and subsequent lung fibrosis partially through suppressing BLM-induced ER stress and oxidative stress.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01514-6.

Latest progress on the molecular mechanisms of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a serious life-threatening lung disease, and the median survival period of PF patients after diagnosis is only 2.5-3.5 years. At present, there are no effective drugs or therapeutics to reverse or even inhibit IPF. The main pathological characteristics of pulmonary fibrosis (PF) include damage to alveolar epithelial cells, fibroblast activation and extracellular matrix accumulation, which gradually lead to damage to the lung structure and decreased lung function. It is important to understand the cellular and molecular mechanisms of PF comprehensively and clearly. In this paper, critical signaling pathways related to PF were reviewed to present updates on the molecular mechanisms of PF.

MiR-200a inversely correlates with Hedgehog and TGF-β canonical/non-canonical trajectories to orchestrate the anti-fibrotic effect of Tadalafil in a bleomycin-induced pulmonary fibrosis model

Few reports have documented the ability of phosphodiesterase-5 inhibitors (PDE-5-Is) to ameliorate idiopathic pulmonary fibrosis (IPF) mainly by their anti-inflammatory/antioxidant capacities, without unveiling the possible molecular mechanisms involved. Because of the recent role of miR-200 family and Sonic Hedgehog (SHH) trajectory in IPF, we have studied their impact on the anti-fibrotic potential of tadalafil against bleomycin-induced pulmonary fibrosis. Animals were allocated into normal-control, bleomycin-fibrotic control, and bleomycin post-treated with tadalafil or dexamethasone, as the reference drug. On the molecular level, tadalafil has reverted the bleomycin effect on all the assessed parameters. Tadalafil upregulated the gene expression of miR-200a, but decreased the smoothened (SMO) and the transcription factors glioma-associated oncogene homolog (Gli-1, Gli-2), members of SHH pathway. Additionally, tadalafil ebbed transforming growth factor (TGF)-β, its canonical (SMAD-3/alpha smooth muscle actin [α-SMA] and Snail), and non-canonical (p-Akt/p-Forkhead box O3 (FOXO3) a) pathways. Besides, a strong negative correlation between miR-200a and the analyzed pathways was proved. The effect of tadalafil was further confirmed by the improved lung structure and the reduced Ashcroft score/collagen deposition. The results were comparable to that of dexamethasone. In conclusion, our study has highlighted the involvement of miR-200a in the anti-fibrotic effect of tadalafil with the inhibition of SHH hub and the pro-fibrotic pathways (TGF-β/ SMAD-3/α-SMA, Snail and p-AKT/p-FOXO3a). Potential anti-fibrotic effect of tadalafil. Modulation of miR200a/SHH/canonical and non-canonical TGF-β trajectories. → : stimulatory effect; ┴: inhibitory effect.

Mallotus furetianus extract protects against ethanol-induced liver injury via the activation of the cAMP-PKA pathway

The protective effects of Mallotus furetianus extract (MF) on liver fibrosis induced with ethanol were examined using in vivo and in vitro model. MF treatment suppressed plasma alanine aminotransferase and aspartate aminotransferase activities in ethanol plus carbon tetrachloride (CCl4)-induced cirrhosis rat model. MF also suppressed the increase in type l collagen and α-smooth muscle actin expression in the livers of ethanol plus CCl4-induced rat by the maintenance of intracellular glutathione levels. Furthermore, we evaluated the effect of MF on the alcohol-induced activation of hepatic stellate cells (HSCs), which are responsible for the increased production and deposition of the extracellular matrix in liver injury. Here, we observed the enhancement of the intracellular reactive oxygen species (ROS) levels and the increase in type I collagen and a-SMA expression in HSCs activated with ethanol. However, the enhanced ROS levels were suppressed with the treatments of MF or diphenyleneiodonium (DPI). Furthermore, the treatment of MF or DPI suppressed the increase in type I collagen and a-SMA expression activated with ethanol. We also observed that the treatment of MF or LY194002 suppressed the increase in type I collagen expression in HSCs activated with ethanol, suggesting that ethanol induced type I collagen expression via the PI3K-Akt signaling pathway. On the other hand, the suppression of the synthesis of type I collagen in ethanol and MF-treated HSCs was inhibited by H-89. From these results, MF may suppress the increase in the activity of NADPH oxidase in HSCs activated with ethanol through the cAMP-PKA pathway.

Human Adventitial Fibroblast Phenotype Depends on the Progression of Changes in Substrate Stiffness

Adventitial fibroblasts (AFs) are major contributors to vascular remodeling and maladaptive cascades associated with arterial disease, where AFs both contribute to and respond to alterations in their surrounding matrix. The relationships between matrix modulus and human aortic AF (AoAF) function are investigated using poly(ethylene glycol)-based hydrogels designed with matrix metalloproteinase (MMP)-sensitive and integrin-binding peptides. Initial equilibrium shear storage moduli for the substrates examined are 0.33, 1.42, and 2.90 kPa; after 42 days of culture, all hydrogels exhibit similar storage moduli (0.3-0.7 kPa) regardless of initial modulus, with encapsulated AoAFs spreading and proliferating. In 10 and 7.5 wt% hydrogels, modulus decreases monotonically throughout culture; however, in 5 wt% hydrogels, modulus increases after an initial 7 days of culture, accompanied by an increase in myofibroblast transdifferentiation and expression of collagen I and III through day 28. Thereafter, significant reductions in both collagens occur, with increased MMP-9 and decreased tissue inhibitor of metalloproteinase-1/-2 production. Releasing cytoskeletal tension or inhibiting cellular protein secretion in 5 wt% hydrogels block the stiffening of the polymer matrix. Results indicate that encapsulated AoAFs initiate cell-mediated matrix remodeling and demonstrate the utility of dynamic 3D systems to elucidate the complex interactions between cell behavior and substrate properties.

Baicalin alleviates bleomycin‑induced pulmonary fibrosis and fibroblast proliferation in rats via the PI3K/AKT signaling pathway

Baicalin is an important flavonoid compound THAT is isolated from the Scutellaria baicalensis Georgi Chinese herb and plays a critical role in anti‑oxidative, anti‑inflammatory, anti‑infection and anti‑tumor functions. Although baicalin can suppress the proliferation of tumor cells, the underlying mechanisms of baicalin in bleomycin (BLM)‑induced pulmonary fibrosis remain to be elucidated. Thus, the aim of the present study was to determine the role of baicalin in pulmonary fibrosis and fibroblast proliferation in rats. Hematoxylin and eosin (H&E) and Masson staining were used to measure the morphology of pulmonary fibrosis, ELIASA kits were used to test the ROS and inflammation, and western blotting and TUNEL were performed to study the apoptosis proteins. In vitro, MTT assay, flow cytometry, western blotting and immunofluorescence were performed to investigate the effects of baicalin on proliferation of fibroblasts. The most significantly fibrotic changes were identified in the lungs of model rats at day 28. Baicalin (50 mg/kg) attenuated the degree of pulmonary fibrosis, and the hydroxyproline content of the lung tissues was decreased in the baicalin group, compared with the BLM group. Further investigation revealed that baicalin significantly increased glutathione peroxidase (GSH‑px), total‑superoxide dismutase (T‑SOD) and glutathione (GSH) levels, whilst decreasing that of serum malondialdehyde (MDA). TUNEL‑positive cells were significantly decreased in rats treated with baicalin group, compared with the model group. Furthermore, it was found that BLM promoted fibroblasts viability in a dose‑dependent manner in vivo, which was restricted following treatment with different concentrations of baicalin. Moreover, BLM promoted the expression levels of cyclin A, D and E, proliferating cell nuclear antigen, phosphorylated (p)‑AKT and p‑calcium/calmodulin‑dependent protein kinase type. BLM also promoted the transition of cells from the G0/G1 phase to the G2/M and S phases, and increased the intracellular Ca2+ concentration, which was subsequently suppressed by baicalin. Collectively, the results of the present study suggested that baicalin exerted a suppressive effect on BLM‑induced pulmonary fibrosis and fibroblast proliferation.

Exogenous supply of Hsp47 triggers fibrillar collagen deposition in skin cell cultures in vitro

Background

Collagen is a structural protein that provides mechanical stability and defined architectures to skin. In collagen-based skin disorders this stability is lost, either due to mutations in collagens or in the chaperones involved in collagen assembly. This leads to chronic wounds, skin fragility, and blistering. Existing approaches to treat such conditions rely on administration of small molecules to simulate collagen production, like 4-phenylbutyrate (4-PBA) or growth factors like TGF-β. However, these molecules are not specific for collagen synthesis, and result in unsolicited side effects. Hsp47 is a collagen-specific chaperone with a major role in collagen biosynthesis. Expression levels of Hsp47 correlate with collagen deposition. This article explores the stimulation of collagen deposition by exogenously supplied Hsp47 (collagen specific chaperone) to skin cells, including specific collagen subtypes quantification.

Results

Here we quantify the collagen deposition level and the types of deposited collagens after Hsp47 stimulation in different in vitro cultures of cells from human skin tissue (fibroblasts NHDF, keratinocytes HaCat and endothelial cells HDMEC) and mouse fibroblasts (L929 and MEF). We find upregulated deposition of fibrillar collagen subtypes I, III and V after Hsp47 delivery. Network collagen IV deposition was enhanced in HaCat and HDMECs, while fibril-associated collagen XII was not affected by the increased intracellular Hsp47 levels. The deposition levels of fibrillar collagen were cell-dependent i.e. Hsp47-stimulated fibroblasts deposited significantly higher amount of fibrillar collagen than Hsp47-stimulated HaCat and HDMECs.

Conclusions

A 3-fold enhancement of collagen deposition was observed in fibroblasts upon repeated dosage of Hsp47 within the first 6 days of culture. Our results provide fundamental understanding towards the idea of using Hsp47 as therapeutic protein to treat collagen disorders.

Cellular senescence and EMT crosstalk in bleomycin-induced pathogenesis of pulmonary fibrosis-an in vitro analysis

With poor prognosis and aberrant lung remodeling, pulmonary fibrosis exhibits worldwide prevalence accompanied by an increase in burden in terms of hospitalization and death. Apart from genetic and non-genetic factors, fibrosis occurs as a side effect of bleomycin antineoplastic activity. Elucidating the cellular and molecular mechanism could help in the development of effective anti-fibrotic treatment strategies. In the present study, we investigated the underlying mechanism behind bleomycin-induced fibrosis using human alveolar epithelial cells (A549 cells). On the basis of the experimental observation, it was demonstrated that with transforming growth factor-β (TGF-β) as a central mediator of fibrosis progression, a cross-talk between epithelial-mesenchymal transition (EMT) and senescence upon bleomycin treatment occurs. This results in the advancement of this serious fibrotic condition. Fibrosis was initiated through integrin activation and imbalance in the redox state (NOX expression) of the cell. It progressed along the TGF-β-mediated non-canonical pathway (via ERK phosphorylation) followed by the upregulation of α-smooth muscle actin and collagen synthesis. Additionally, in this process, the loss of the epithelial marker E-cadherin was observed. Furthermore, the expressions of senescence markers, such as p21 and p53, were upregulated upon bleomycin treatment, thereby intensifying the fibrotic condition. Accordingly, the molecular pathway mediating the bleomycin-induced fibrosis was explored in the current study.

Constitutive AKT Activity Predisposes Lung Fibrosis by Regulating Macrophage, Myofibroblast and Fibrocyte Recruitment and Changes in Autophagy

The etiology and pathogenesis of pulmonary fibrosis is poorly understood. We and others reported that M-CSF/CSF-1, M-CSF-R and downstream AKT activation plays an important role in lung fibrosis in mice models and in IPF patients. To understand potential molecular pathways used by M-CSF-R activation to direct lung fibrosis, we used a novel transgenic mouse model that expresses a constitutively-active form of AKT, myristoylated AKT (Myr-Akt), driven by the c-fms (M-CSF-R) promoter. We were particularly interested in the basal immune state of the lungs of these Myr-Akt mice to assess M-CSF-R-related priming for lung fibrosis. In support of a priming effect, macrophages isolated from the lungs of unchallenged Myr-Akt mice displayed an M2-tropism, enhanced co-expression of M-CSF-R and α-SMA, reduced autophagy reflected by reduced expression of the key autophagy genes Beclin-1, MAP1-Lc3a(Lc3a), and MAP1-Lc3b(Lc3b), and increased p62/STSQM1 expression compared with littermate WT mice. Furthermore, Myr-Akt mice had more basal circulating fibrocytes than WT mice. Lastly, upon bleomycin challenge, Myr-Akt mice showed enhanced collagen deposition, increased F4/80+ and CD45+ cells, reduced autophagy genes Beclin-1, Lc3a, and Lc3b expression, and a shorter life-span than WT littermates. These data provide support that M-CSF-R/AKT activation may have a priming effect which can predispose lung tissue to pulmonary fibrosis.

Tackling MARCKS-PIP3 circuit attenuates fibroblast activation and fibrosis progression

Targeting activated fibroblasts, including myofibroblast differentiation, has emerged as a key therapeutic strategy in patients with idiopathic pulmonary fibrosis (IPF). However, there is no available therapy capable of selectively eradicating myofibroblasts or limiting their genesis. Through an integrative analysis of the regulator genes that are responsible for the activation of IPF fibroblasts, we noticed the phosphatidylinositol 4,5-bisphosphate (PIP2)-binding protein, myristoylated alanine-rich C-kinase substrate (MARCKS), as a potential target molecule for IPF. Herein, we have employed a 25-mer novel peptide, MARCKS phosphorylation site domain sequence (MPS), to determine if MARCKS inhibition reduces pulmonary fibrosis through the inactivation of PI3K/protein kinase B (AKT) signaling in fibroblast cells. We first observed that higher levels of MARCKS phosphorylation and the myofibroblast marker α-smooth muscle actin (α-SMA) were notably overexpressed in all tested IPF lung tissues and fibroblast cells. Treatment with the MPS peptide suppressed levels of MARCKS phosphorylation in primary IPF fibroblasts. A kinetic assay confirmed that this peptide binds to phospholipids, particularly PIP2, with a dissociation constant of 17.64 nM. As expected, a decrease of phosphatidylinositol (3,4,5)-trisphosphate pools and AKT activity occurred in MPS-treated IPF fibroblast cells. MPS peptide was demonstrated to impair cell proliferation, invasion, and migration in multiple IPF fibroblast cells in vitro as well as to reduce pulmonary fibrosis in bleomycin-treated mice in vivo. Surprisingly, we found that MPS peptide decreases α-SMA expression and synergistically interacts with nintedanib treatment in IPF fibroblasts. Our data suggest MARCKS as a druggable target in pulmonary fibrosis and also provide a promising antifibrotic agent that may lead to effective IPF treatments.-Yang, D. C., Li, J.-M., Xu, J., Oldham, J., Phan, S. H., Last, J. A., Wu, R., Chen, C.-H. Tackling MARCKS-PIP3 circuit attenuates fibroblast activation and fibrosis progression.

Current advances in idiopathic pulmonary fibrosis: the pathogenesis, therapeutic strategies and candidate molecules

Idiopathic pulmonary fibrosis (IPF) is a type of chronic, progressive lung disease with unknown cause, which is characterized by increasing dyspnea and destruction of lung function with a high mortality rate. Evolving evidence demonstrated that the pathogenesis of IPF involved multiple signaling pathways such as inflammation, oxidative stress and fibrosis. However, drug discovery to prevent or revert IPF has been insufficient to cope with the development. Drug discovery targeting multiple links should be considered. In this review, we will brief the pathogenesis of IPF and discuss several small chemical entities toward the pathogenesis for IPF studied in animal models and clinical trials. The field of novel anti-IPF agents and the future directions for the prevention and treatment of IPF are detailed thoroughly discussed.

Silencing PDK1 limits hypoxia-induced pulmonary arterial hypertension in mice via the Akt/p70S6K signaling pathway

The present study aimed to investigate the effect of phosphoinositide-dependent protein kinase-1 (PDK1) on hypoxia-induced pulmonary arterial hypertension (PAH). A mouse model of hypoxia-induced PAH was generated using normal or PDK1-knockout mice. Histological analysis and hemodynamic evaluations were performed to identify the progression of PAH. The expression and phosphorylation of PDK1/protein kinase B (Akt) signaling pathway associated proteins were detected by western blot analysis. Increased lung vessel thickness, right ventricular (RV) systolic pressure (RVSP), RV hypertrophy index (RVHI) values [the RV weight-to-left ventricular (LV) plus septum (S) weight ratio] and PDK1 expression were observed in the hypoxia-induced PAH model compared with the normal control. The phosphorylation of Akt^T308, proline-rich Akt1 substrate 1 (PRAS40) and S6KT²²⁹ was also notably increased in the PAH model compared with the control. The changes of proteins were not observed in the hypoxia treated PDK1^flox/+ : Tie2-Cre mice. Similarly, the RVSP and RVHI values, and PDK1 expression were reduced in the hypoxia treated PDK1^flox/+: Tie2-Cre mice to a level comparable with those in the control, suggesting that PDK1 partial knockout significantly limited hypoxia-induced PAH. The results of the present study indicate that PDK1 is essential for hypoxia-induced PAH through the PDK1/Akt/S6K signaling cascades.

Inhalation of the prodrug PI3K inhibitor CL27c improves lung function in asthma and fibrosis

PI3K activation plays a central role in the development of pulmonary inflammation and tissue remodeling. PI3K inhibitors may thus offer an improved therapeutic opportunity to treat non-resolving lung inflammation but their action is limited by unwanted on-target systemic toxicity. Here we present CL27c, a prodrug pan-PI3K inhibitor designed for local therapy, and investigate whether inhaled CL27c is effective in asthma and pulmonary fibrosis. Mice inhaling CL27c show reduced insulin-evoked Akt phosphorylation in lungs, but no change in other tissues and no increase in blood glycaemia, in line with a local action. In murine models of acute or glucocorticoid-resistant neutrophilic asthma, inhaled CL27c reduces inflammation and improves lung function. Finally, inhaled CL27c administered in a therapeutic setting protects from bleomycin-induced lung fibrosis, ultimately leading to significantly improved survival. Therefore, local delivery of a pan-PI3K inhibitor prodrug reduces systemic on-target side effects but effectively treats asthma and irreversible pulmonary fibrosis.

Activation of PI3K plays a role in pulmonary inflammation. Here, the authors develop a drug inhibitor of PI3K, and show that it inhibits lung inflammation and damage in mouse models of asthma and lung fibrosis.

New therapeutics based on emerging concepts in pulmonary fibrosis

INTRODUCTION

Fibrosis is an irreversible pathological endpoint in many chronic diseases, including pulmonary fibrosis. Idiopathic pulmonary fibrosis (IPF) is a progressive and often fatal condition characterized by (myo)fibroblast proliferation and transformation in the lung, expansion of the extracellular matrix, and extensive remodeling of the lung parenchyma. Recent evidence indicates that IPF prevalence and mortality rates are growing in the United States and elsewhere. Despite decades of research on the pathogenic mechanisms of pulmonary fibrosis, few therapeutics have succeeded in the clinic, and they have failed to improve IPF patient survival. Areas covered: Based on a literature search and our own results, we discuss the key cellular and molecular responses that contribute to (myo)fibroblast actions and pulmonary fibrosis pathogenesis; this includes signaling pathways in various cells that aberrantly and persistently activate (myo)fibroblasts in fibrotic lesions and promote scar tissue formation in the lung. Expert opinion: Lessons learned from recent failures and successes with new therapeutics point toward approaches that can target multiple pro-fibrotic processes in IPF. Advances in preclinical modeling and single-cell genomics will also accelerate novel discoveries for effective treatment of IPF.

Reactive Oxygen Species Are Necessary for Bleomycin A5-Induced Apoptosis and Extracellular Matrix Elimination of Nasal Polyp-Derived Fibroblasts

BACKGROUND:

The pathology of chronic rhinosinusitis with nasal polyp (CRSwNP) is characterized by the infiltration of a large number of fibroblasts, resulting in extracellular matrix (ECM) deposition. Intralesional bleomycin A5 (BLE) injection has proved to be effective and safe, providing a novel treatment for CRSwNP. However, the mechanism is not clearly understood.

OBJECTIVES:

The aim of this study is to explore the possible mechanism of BLE-induced apoptosis in nasal polyp-derived fibroblasts (NPDFs).

MATERIAL AND METHODS:

Dichloro-dihydro-fluorescein diacetate probe, cell migration assays, and cell cycle analysis were used to detect the growth characteristics and basal reactive oxygen species (ROS) traits of NPDFs. Annexin V/propidium iodide and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay was used to detect BLE-induced apoptosis. As a control, the antioxidant glutathione (GSH) was used to abrogate ROS induced by BLE. Western blot analysis was used to evaluate the effects of BLE on apoptosis and the ECM proteins of NPDFs.

RESULTS:

The results showed that NPDFs had more active growth characteristics and higher basal ROS levels than normal nasal mucosa fibroblasts (NMFCs). NPDFs were more sensitive to BLE-induced apoptosis and ROS accumulation. GSH abrogation inhibits BLE-induced ECM degradation and apoptosis in NPDFs through a mitochondrial-mediated pathway.

CONCLUSIONS:

BLE induced NPDF apoptosis and ECM degradation through a mitochondrial-mediated pathway and in a ROS-dependent manner.

Unraveling SSc Pathophysiology; The Myofibroblast

Systemic sclerosis (SSc) is a severe auto-immune disease, characterized by vasculopathy and fibrosis of connective tissues. SSc has a high morbidity and mortality and unfortunately no disease modifying therapy is currently available. A key cell in the pathophysiology of SSc is the myofibroblast. Myofibroblasts are fibroblasts with contractile properties that produce a large amount of pro-fibrotic extracellular matrix molecules such as collagen type I. In this narrative review we will discuss the presence, formation, and role of myofibroblasts in SSc, and how these processes are stimulated and mediated by cells of the (innate) immune system such as mast cells and T helper 2 lymphocytes. Furthermore, current novel therapeutic approaches to target myofibroblasts will be highlighted for future perspective.