Lung Fibrosis and Fibrosis in the Lungs: Is It All about Myofibroblasts?

Role of macrophages in peritoneal dialysis-associated peritoneal fibrosis

Peritoneal dialysis (PD) can be used as renal replacement therapy when chronic kidney disease (CKD) progresses to end-stage renal disease. However, peritoneal fibrosis (PF) is a major cause of PD failure. Studies have demonstrated that PD fluid contains a significantly larger numbers of macrophages compared with the healthy individuals. During PD, macrophages can secrete cytokines to keep peritoneal tissue in sustained low-grade inflammation, and participate in the regulation of fibrosis-related signaling pathways, such as NF-κB, TGF-β/Smad, IL4/STAT6, and PI3K/AKT. A series of basic pathological changes occurs in peritoneal tissues, including epithelial mesenchymal transformation, overgeneration of neovasculature, and abnormal deposition of extracellular matrix. This review focuses on the role of macrophages in promoting PF during PD, summarizes the targets of macrophage-related inhibition of fibrosis, and provides new ideas for clinical research on delaying PF, maintaining the function and integrity of peritoneum, prolonging duration of PD as a renal replacement modality, and achieving longer survival in CKD patients.

Hyperglycaemia-induced fibrotic and inflammatory gene expression alterations in lung epithelial cells: Implications for pulmonary fibrosis development

Hyperglycaemia has a significant long-term impact on multiple organ systems, including renal, cardiovascular, central nervous, hepatic and ocular systems, leading to the gradual loss of their functional abilities. Numerous studies have elucidated the pathophysiology, etiology, and consequences of hyperglycaemia on these organs. The pulmonary system is also considered as a target of hyperglycaemia, several factors cause lung injury which leads to the development of pulmonary fibrosis, a chronic fibrotic disease with usual interstitial pneumonia patterns. Nevertheless, the effects of hyperglycaemia on the development of pulmonary fibrosis remain poorly understood. We intend to understand the cellular and morphological changes, and the progression of fibrosis in lung epithelial cells subjected to hyperglycaemia. Our experimental data indicate that hyperglycaemia induces fibrotic and inflammatory alterations in cultured lung epithelial cells. These alterations are facilitated by the upregulation of genes related to fibrosis and inflammation, promoting cell proliferation and migration. Further research is required to comprehensively elucidate the impact of hyperglycaemia during lung injury progression of fibrosis, these findings may reveal novel mechanisms that may help in the assessment and treatment of lung ailments in people with hyperglycaemia.

In silico screening and validation of natural compounds with fabrication and characterization of a lead compound-loaded chitosome for targeting lung fibrosis

Lung fibrosis (LF) is a serious complication with very limited therapeutic options. This study aimed to find a potential compound for targeting LF and develop a chitosome formulation to minimize any inherent drawbacks of the compound and achieve effective drug delivery. In total, 79 natural compounds were screened using an in silico approach against five targeted proteins (3HMG, 6B8Y, 2FAP, 3CQU, and 3DK9). Amongst these, quercetin (QER) exhibited the best efficacy (-14.725 kcal mol-1) and ΔG average (-86.45 ± 6.24) kcal mol-1 against the TGF-β receptor (PDB ID: 6B8Y). In vitro studies revealed that bleomycin-challenged A549 cells showed a fibrosis-like behaviour. Upon treatment with QER, the cell viability decreased owing to a reduction in the mitochondrial membrane potential and increased apoptosis. Furthermore, cell migration was inhibited with an improvement in cellular morphology. A QER-loaded chitosome formulation (QCF) was prepared through modified thin-film hydration. Variables were optimized using a response surface methodology Box-Behnken design. The QCF was further characterized on the basis of microscopic observation, zeta potential, entrapment efficiency, drug release and kinetics and by evaluating the effect of temperature on the QCF. Its zeta potential was +24.83 ± 0.32 mV, while microscopic observation showed that it had a spherical morphology with slightly rough surfaces after chitosan coating. Furthermore, the EE% was determined to be 81.75 ± 0.46%. The QCF also demonstrated a 74.23 ± 1.01% release of QER till 24 h, following Higuchi model kinetics. In conclusion, the in silico and in vitro cell line studies provided evidence for QER as a lead molecule for targeting LF. Moreover, the prepared QCF demonstrated sustained release with prospective QER targeted delivery. However, further extensive research is required to provide a promising strategy for the management of LF in the future.

Proinflammatory Cytokines in Chronic Respiratory Diseases and Their Management

Pulmonary homeostasis can be agitated either by external environmental insults or endogenous factors produced during respiratory/pulmonary diseases. The lungs counter these insults by initiating mechanisms of inflammation as a localized, non-specific first-line defense response. Cytokines are small signaling glycoprotein molecules that control the immune response. They are formed by numerous categories of cell types and induce the movement, growth, differentiation, and death of cells. During respiratory diseases, multiple proinflammatory cytokines play a crucial role in orchestrating chronic inflammation and structural changes in the respiratory tract by recruiting inflammatory cells and maintaining the release of growth factors to maintain inflammation. The issue aggravates when the inflammatory response is exaggerated and/or cytokine production becomes dysregulated. In such instances, unresolving and chronic inflammatory reactions and cytokine production accelerate airway remodeling and maladaptive outcomes. Pro-inflammatory cytokines generate these deleterious consequences through interactions with receptors, which in turn initiate a signal in the cell, triggering a response. The cytokine profile and inflammatory cascade seen in different pulmonary diseases vary and have become fundamental targets for advancement in new therapeutic strategies for lung diseases. There are considerable therapeutic approaches that target cytokine-mediated inflammation in pulmonary diseases; however, blocking specific cytokines may not contribute to clinical benefit. Alternatively, broad-spectrum anti-inflammatory approaches are more likely to be clinically effective. Herein, this comprehensive review of the literature identifies various cytokines (e.g., interleukins, chemokines, and growth factors) involved in pulmonary inflammation and the pathogenesis of respiratory diseases (e.g., asthma, chronic obstructive pulmonary, lung cancer, pneumonia, and pulmonary fibrosis) and investigates targeted therapeutic treatment approaches.

Metabolomic Biomarkers of Pulmonary Fibrosis in COVID-19 Patients One Year After Hospital Discharge

Coronavirus disease 2019 (COVID-19) global pandemic has affected more than 600 million people up to date. The symptomatology and severity of COVID-19 are very broad, and there are still concerns about the long-term sequelae that it can have on discharged patients. The development of pulmonary fibrotic sequelae after this infection is especially worrying. Our aim was to determine if there was a metabolomic signature that could predict the development of pulmonary fibrotic sequelae. It is a multicenter prospective observation subcohort based on the COVID-FIBROTIC study. A metabolomic analysis was performed by nuclear magnetic resonance (NMR) on serum samples from patients admitted with bilateral COVID-19 pneumonia collected 2 months after hospital discharge. One year after admission, clinical, functional and radiological data were collected from these same patients. Finally, 109 patients (mean age 57.68 [DS14.03], 65.13% male) were available. Fibrotic sequelae 1 year after COVID-19 disease were found in 33% of them. Based on the NMR analysis of the serum samples, it was possible to distinguish with 80.82% of sensitivity, 72.22% of specificity and 0.83 of an area under the curve (AUC) value which patients would have radiological signs of pulmonary fibrotic pattern 1 year after sample collection. According to the metabolites participating in the discriminative model and the univariate statistics, glucose, valine, and fatty acids (═CH-CH2-CH═) were suggested as potential biomarkers of the development of pulmonary fibrotic sequelae after COVID-19. TRIAL REGISTRATION NUMBER: clinicaltrials.gov NCT04409275 (June 1, 2020).

Network Pharmacology-driven therapeutic interventions for Interstitial Lung Diseases using Traditional medicines: A Narrative Review

This review explores the progressive domain of network pharmacology and its potential to revolutionize therapeutic approaches for Interstitial Lung Diseases (ILDs), a collective term encompassing Interstitial Pneumonia, Pneumoconiosis, Connective Tissue Disease-related ILDs, and Sarcoidosis. The exploration focuses on the profound legacy of traditional medicines, particularly Ayurveda and Traditional Chinese Medicines (TCM), and their largely unexplored capacity in ILD treatment. These ancient healing systems, characterized by their holistic methodologies and multifaceted treatment modalities, offer a promising foundation for discovering innovative therapeutic strategies. Moreover, the review underscores the amalgamation of artificial intelligence (AI) and machine learning (ML) methodologies with bioinformatics, creating a computational synergy capable of deciphering the intricate biological networks associated with ILDs. Network pharmacology has tailored the hypothesis from the conventional "one target, one drug" towards a "network target, multi-component therapeutics" approach. The fusion of traditional literature and computational technology can unveil novel drugs, targets, and pathways, augmenting effective therapies and diminishing adverse effects related to current medications. In conclusion, this review provides a comprehensive exposition of how Network Pharmacology tools can leverage the insights of Ayurveda and TCM to craft efficacious therapeutic solutions for ILDs. It sets the stage for future investigations in this captivating interdisciplinary domain, validating the use of traditional medicines worldwide.

Probing the effects of dextran-coated CeO2 nanoparticles on lung fibroblasts using multivariate single-cell Raman spectroscopy

In this study, we investigated the cytotoxic effect of highly soluble dextran-coated CeO2 nanoparticles on human fetal lung fibroblasts MRC-5. We examined individual nanoparticle-treated cells by Raman spectroscopy and analyzed Raman spectra using non-negative principal component analysis and k-means clustering. In this way, we determined dose-dependent differences between treated cells, which were reflected through the intensity change of lipid, phospholipid and RNA-related Raman modes. Performing standard biological tests for cell growth, viability and induction of apoptosis in parallel, these changes were correlated with nanoparticle-induced apoptotic processes. The cells with specific spectral characteristics, referring to non-apoptotic, but possibly autophagic cell death modality, were also detected. Additionally, Raman imaging combined with principal component and vertex component analysis was used to map the spatial distribution of biological molecules in treated and untreated cells. This work provided the description of different resulting states of the treated cells depending on the dextran-coated CeO2 nanoparticles dose, which can be later used in the design of the nanoparticles for industrial or medical applications. The wide content of information resulting from single-cell Raman spectroscopy has the potential to detect biochemical changes caused by nanoparticles that would otherwise require a series of expensive and time-consuming standard biological techniques.

Ameliorative effects of avocado oil on bleomycin-induced lung fibrosis and oxidative stress in rats

Pulmonary fibrosis (PF), is a chronic interstitial lung disease, characterized by changes in the alveoli, excessive accumulation of extracellular matrix, persistent inflammation, and oxidative stress. In this study, we aimed to explore the therapeutic effects of avocado oil (Ao) on bleomycin (BLM)-induced PF. Four this, 24 male rats were divided into four groups (n = 6): the first group served as a control, the second served as a fibrotic group, instilled intratracheally only with BLM (2 mg/kg bw), and the remaining groups were treated by gastric gavage with Ao at different doses (3.5 and 5 mL/kg bw) for 25 days after BLM instillation. The fibrosis induction revealed significant alterations, including increased lipid peroxidation and decreased antioxidant enzyme activities such as superoxyde dismutase (SOD) and catalase (CAT), level of thiols group coupled with a high fibrosis score (FS) and an inflammatory index (II), along with excessive collagen deposition in the pulmonary interstitium. Ao treatment reversed all disturbances induced by BLM in oxidative stress parameters and relatively repairs the histological damage caused by BLM by reducing the FS and the II. The antioxidant, anti-inflammatory and anti-fibrosis power of Ao, may suggest this last as a promising candidate for the treatment of PF.

A regularized Bayesian Dirichlet-multinomial regression model for integrating single-cell-level omics and patient-level clinical study data

The abundance of various cell types can vary significantly among patients with varying phenotypes and even those with the same phenotype. Recent scientific advancements provide mounting evidence that other clinical variables, such as age, gender, and lifestyle habits, can also influence the abundance of certain cell types. However, current methods for integrating single-cell-level omics data with clinical variables are inadequate. In this study, we propose a regularized Bayesian Dirichlet-multinomial regression framework to investigate the relationship between single-cell RNA sequencing data and patient-level clinical data. Additionally, the model employs a novel hierarchical tree structure to identify such relationships at different cell-type levels. Our model successfully uncovers significant associations between specific cell types and clinical variables across three distinct diseases: pulmonary fibrosis, COVID-19, and non-small cell lung cancer. This integrative analysis provides biological insights and could potentially inform clinical interventions for various diseases.

Citrullinated and malondialdehyde-acetaldehyde-modified fibrinogen activates macrophages and promotes profibrotic responses in human lung fibroblasts

The objective of this study was to assess fibrinogen (FIB) comodified with citrulline (CIT) and/or malondialdehyde-acetaldehyde (MAA) initiates macrophage-fibroblast interactions, leading to extracellular matrix (ECM) deposition that characterizes rheumatoid arthritis-associated interstitial lung disease (RA-ILD). Macrophages (Mϕ) were stimulated with native-FIB, FIB-CIT, FIB-MAA, or FIB-MAA-CIT. Supernatants (SNs) [Mϕ-SN (U-937-derived) or MϕP-SN (PBMC-derived)] or direct antigens were coincubated with human lung fibroblasts (HLFs). Gene expression was examined using RT-PCR. ECM deposition was quantified using immunohistochemistry and Western blot; cell signaling mechanisms were delineated. Platelet-derived growth factor (PDGF)-BB and TGF-β were measured in macrophage supernatants, and inhibition studies were performed using Su16f and SB431542, respectively. HLF gene expression of CD36, COL6A3, MMP-9, MMP-10, and MMP-12 was increased following stimulations with Mϕ-SN generated from modified FIB but not from direct antigens. HLF stimulated with MϕP-SNFIB-MAA-CIT derived from patients with RA-ILD resulted in 4- to 30-fold increases in COL6A3 and MMP12 expression; upregulation was greater in HLFs stimulated with MϕP-SN derived from RA-ILD versus controls. HLF exposure to Mϕ-SNFIB-MAA-CIT increased types I/VI collagen deposition versus all other Mϕ-SN groups and was greater than FIB-MAA-CIT stimulation. PDGF-BB and TGF-β signaling had the highest concentrations identified in Mϕ-SNFIB-MAA-CIT and MϕP-SNFIB-MAA-CIT, particularly from RA-ILD-derived cells. PDGF-BB and TGF-β inhibitors, alone and in combination, significantly reduced HLF-mediated ECM deposition from Mϕ-SN stimulations. These results show that comodified fibrinogen activates macrophages to produce PDGF-BB and TGF-β that promotes an aggressive HLF phenotype characterized by increased ECM deposition. These results suggest that targeting CIT and/or MAA modifications or downstream cellular signals could represent novel approaches to RA-ILD treatment.NEW & NOTEWORTHY This report demonstrates that fibrinogen simultaneously harboring two common posttranslational modifications activates macrophages to secrete platelet-derived growth factor (PDGF)-BB and transforming growth factor (TGF)-β. Resulting cross talk between activated macrophages and human lung fibroblasts leads to marked increases in extracellular matrix deposition. These protein modifications are abundant and colocalize in lung tissues from patients with rheumatoid arthritis-associated interstitial lung disease (RA-ILD), and the results suggest that agents targeting citrullination and/or malondialdehyde-acetaldehyde (MAA) adduct formation could represent novel therapeutic strategies.

The role of epithelial-mesenchymal transition in pulmonary fibrosis: lessons from idiopathic pulmonary fibrosis and COVID-19

Despite the tremendous advancements in the knowledge of the pathophysiology and clinical aspects of SARS-CoV-2 infection, still many issues remain unanswered, especially in the long-term effects. Mounting evidence suggests that pulmonary fibrosis (PF) is one of the most severe complications associated with COVID-19. Therefore, understanding the molecular mechanisms behind its development is helpful to develop successful therapeutic strategies. Epithelial to mesenchymal transition (EMT) and its cell specific variants endothelial to mesenchymal transition (EndMT) and mesothelial to mesenchymal transition (MMT) are physio-pathologic cellular reprogramming processes induced by several infectious, inflammatory and biomechanical stimuli. Cells undergoing EMT acquire invasive, profibrogenic and proinflammatory activities by secreting several extracellular mediators. Their activity has been implicated in the pathogenesis of PF in a variety of lung disorders, including idiopathic pulmonary fibrosis (IPF) and COVID-19. Aim of this article is to provide an updated survey of the cellular and molecular mechanisms, with emphasis on EMT-related processes, implicated in the genesis of PF in IFP and COVID-19.

Interplay between Lung Diseases and Viral Infections: A Comprehensive Review

The intricate relationship between chronic lung diseases and viral infections is a significant concern in respiratory medicine. We explore how pre-existing lung conditions, including chronic obstructive pulmonary disease, asthma, and interstitial lung diseases, influence susceptibility, severity, and outcomes of viral infections. We also examine how viral infections exacerbate and accelerate the progression of lung disease by disrupting immune responses and triggering inflammatory pathways. By summarizing current evidence, this review highlights the bidirectional nature of these interactions, where underlying lung diseasesincrease vulnerability to viral infections, while these infections, in turn, worsen the clinical course. This review underscores the importance of preventive measures, such as vaccination, early detection, and targeted therapies, to mitigate adverse outcomes in patients with chronic lung conditions. The insights provided aim to inform clinical strategies that can improve patient management and reduce the burden of chronic lung diseases exacerbated by viral infections.

A novel senolytic drug for pulmonary fibrosis: BTSA1 targets apoptosis of senescent myofibroblasts by activating BAX

Idiopathic pulmonary fibrosis is a progressive and age-related disease that results from impaired lung repair following injury. Targeting senescent myofibroblasts with senolytic drugs attenuates pulmonary fibrosis, revealing a detrimental role of these cells in pulmonary fibrosis. The mechanisms underlying the occurrence and persistence of senescent myofibroblasts in fibrotic lung tissue require further clarification. In this study, we demonstrated that senescent myofibroblasts are resistant to apoptosis by upregulating the proapoptotic protein BAX and antiapoptotic protein BCL-2 and BCL-XL, leading to BAX inactivation. We further showed that high levels of inactive BAX-mediated minority mitochondrial outer membrane permeabilization (minority MOMP) promoted DNA damage and myofibroblasts senescence after insult by a sublethal stimulus. Intervention of minority MOMP via the inhibition of caspase activity by quinolyl-valyl-O-methylaspartyl-[2,6-difluorophenoxy]-methyl ketone (QVD-OPH) or BAX knockdown significantly reduced DNA damage and ultimately delayed the progression of senescence. Moreover, the BAX activator BTSA1 selectively promoted the apoptosis of senescent myofibroblasts, as BTSA1-activated BAX converted minority MOMP to complete MOMP while not injuring other cells with low levels of BAX. Furthermore, therapeutic activation of BAX with BTSA1 effectively reduced the number of senescent myofibroblasts in the lung tissue and alleviated both reversible and irreversible pulmonary fibrosis. These findings advance the understanding of apoptosis resistance and cellular senescence mechanisms in senescent myofibroblasts in pulmonary fibrosis and demonstrate a novel senolytic drug for pulmonary fibrosis treatment.

What every clinician should know about inflammation in COPD

Inflammation drives COPD pathogenesis and exacerbations. Although the conceptual framework and major players in the inflammatory milieu of COPD have been long established, the nuances of cellular interactions and the etiological differences that create heterogeneity in inflammatory profiles and treatment response continue to be revealed. This wealth of data and understanding is not only a boon to the researcher but also provides guidance to the clinician, moving the field closer to precision medicine. It is through this lens that this review seeks to describe the inflammatory processes at play in COPD, relating inflammation to pathological and functional changes, identifying patient-specific and disease-related factors that may influence clinical observations, and providing current insights on existing and emerging anti-inflammatory treatments and treatment targets, including biological therapies and phosphodiesterase (PDE) inhibitors.

BRD4: an effective target for organ fibrosis

Fibrosis is an excessive wound-healing response induced by repeated or chronic external stimuli to tissues, significantly impacting quality of life and primarily contributing to organ failure. Organ fibrosis is reported to cause 45% of all-cause mortality worldwide. Despite extensive efforts to develop new antifibrotic drugs, drug discovery has not kept pace with the clinical demand. Currently, only pirfenidone and nintedanib are approved by the FDA to treat pulmonary fibrotic illness, whereas there are currently no available antifibrotic drugs for hepatic, cardiac or renal fibrosis. The development of fibrosis is closely related to epigenetic alterations. The field of epigenetics primarily studies biological processes, including chromatin modifications, epigenetic readers, DNA transcription and RNA translation. The bromodomain and extra-terminal structural domain (BET) family, a class of epigenetic readers, specifically recognizes acetylated histone lysine residues and promotes the formation of transcriptional complexes. Bromodomain-containing protein 4 (BRD4) is one of the most well-researched proteins in the BET family. BRD4 is implicated in the expression of genes related to inflammation and pro-fibrosis during fibrosis. Inhibition of BRD4 has shown promising anti-fibrotic effects in preclinical studies; however, no BRD4 inhibitor has been approved for clinical use. This review introduces the structure and function of BET proteins, the research progress on BRD4 in organ fibrosis, and the inhibitors of BRD4 utilized in fibrosis. We emphasize the feasibility of targeting BRD4 as an anti-fibrotic strategy and discuss the therapeutic potential and challenges associated with BRD4 inhibitors in treating fibrotic diseases.

Rheumatoid arthritis extra-articular lung disease: new insights on pathogenesis and experimental drugs

INTRODUCTION

Pulmonary involvement is one of the most common extra-articular manifestations of rheumatoid arthritis (RA), a systemic inflammatory disease characterized by joint swelling and tenderness. All lung compartments can be interested in the course of RA, including parenchyma, airways, and, more rarely, pleura and vasculature.

AREAS COVERED

The aim of this paper is to review the main RA lung manifestations, focusing on pathogenesis, clinical and therapeutic issues of RA-related interstitial lung disease (ILD). Despite an increasing number of studies in the last years, pathogenesis of RA-ILD remains largely debated and the treatment of RA patients with lung involvement is still challenging in these patients.

EXPERT OPINION

Management of RA-ILD is largely based on expert-opinion. Due to the broad clinical manifestations, including both joints and pulmonary involvement, multidisciplinary discussion, including rheumatologist and pulmonologist, is essential, not only for diagnosis, but also to evaluate the best therapeutic approach and follow-up. In fact, the coexistence of different lung manifestations may influence the treatment response and safety. The identification of biomarkers and risk-factors for an early identification of RA patients at risk of developing ILD remains a need that still needs to be fulfilled, and that will require further investigation in the next years.

Molecular changes underlying pulmonary emphysema and chronic bronchitis in Chronic Obstructive Pulmonary Disease: An updated review

The aim of this review is to update and synthesize the molecular mechanisms that lead to the heterogeneous effect on tissue remodeling observed in the two most important clinical phenotypes of chronic obstructive pulmonary disease (COPD), pulmonary emphysema (PE) and chronic bronchitis (CB). Clinical and experimental evidence suggests that this heterogeneous response to promote PE, CB, or both, is related to differentiated genetic, epigenetic, and molecular conditions. Specifically, a tendency toward PE could be related to a variant in the DSP gene, SIRT1 downregulation, macrophage polarization to M1, as well as the involvement of the noncanonical Wnt5A signaling pathway, among other alterations. Additionally, in advanced stages of COPD, PE development is potentiated by dysregulations in autophagy, which promotes senescence and subsequently cell apoptosis, through exacerbated inflammasome activation and release of caspases. On the other hand, CB or the pro-fibrotic phenotype could be potentiated by the downregulated activity of HDAC2, the activation of the TGF-β/Smad or Wnt/β-catenin signaling pathways, macrophage polarization to M2, upregulation of TIMP-1, and/or the presence of the epithelial-mesenchymal transition (EMT) mechanism. Interestingly, the upregulated activity of MMPs, especially MMP-9, is widely involved in the development of both phenotypes. Furthermore, MMP-9 and MMP-12 enhance the severity, perpetuation, and exacerbation of COPD, as well as the development of autoimmunity in this disease.

Lung injury-induced activated endothelial cell states persist in aging-associated progressive fibrosis

Progressive lung fibrosis is associated with poorly understood aging-related endothelial cell dysfunction. To gain insight into endothelial cell alterations in lung fibrosis we performed single cell RNA-sequencing of bleomycin-injured lungs from young and aged mice. Analysis reveals activated cell states enriched for hypoxia, glycolysis and YAP/TAZ activity in ACKR1+ venous and TrkB+ capillary endothelial cells. Endothelial cell activation is prevalent in lungs of aged mice and can also be detected in human fibrotic lungs. Longitudinal single cell RNA-sequencing combined with lineage tracing demonstrate that endothelial activation resolves in young mouse lungs but persists in aged ones, indicating a failure of the aged vasculature to return to quiescence. Genes associated with activated lung endothelial cells states in vivo can be induced in vitro by activating YAP/TAZ. YAP/TAZ also cooperate with BDNF, a TrkB ligand that is reduced in fibrotic lungs, to promote capillary morphogenesis. These findings offer insights into aging-related lung endothelial cell dysfunction that may contribute to defective lung injury repair and persistent fibrosis.

Amelioration of Fibrosis via S1P Inhibition Is Regulated by Inactivation of TGF-β and SPL Pathways in the Human Cornea

Human corneal fibrosis can lead to opacity and ultimately partial or complete vision loss. Currently, corneal transplantation is the only treatment for severe corneal fibrosis and comes with the risk of rejection and donor shortages. Sphingolipids (SPLs) are known to modulate fibrosis in various tissues and organs, including the cornea. We previously reported that SPLs are tightly related to both, transforming growth factor beta (TGF-β) signaling and corneal fibrogenesis. The aim of this study was to investigate the effects of sphingosine-1-phosphate (S1P) and S1P inhibition on specific TGF-β and SPL family members in corneal fibrosis. Healthy human corneal fibroblasts (HCFs) were isolated and cultured in EMEM + FBS + VitC (construct medium) on 3D transwells for 4 weeks. The following treatments were prepared in a construct medium: 0.1 ng/mL TGF-β1 (β1), 1 μM sphingosine-1-phosphate (S1P), and 5 μM Sphingosine kinase inhibitor 2 (I2). Five groups were tested: (1) control (no treatment); rescue groups; (2) β1/S1P; (3) β1/I2; prevention groups; (4) S1P/β1; and (5) I2/β1. Each treatment was administered for 2 weeks with one treatment and switched to another for 2 weeks. Using Western blot analysis, the 3D constructs were examined for the expression of fibrotic markers, SPL, and TGF-β signaling pathway members. Scratch assays from 2D cultures were also utilized to evaluate cell migration We observed reduced fibrotic expression and inactivation of latent TGF-β binding proteins (LTBPs), TGF-β receptors, Suppressor of Mothers Against Decapentaplegic homologs (SMADs), and SPL signaling following treatment with I2 prevention and rescue compared to S1P prevention and rescue, respectively. Furthermore, we observed increased cell migration following stimulation with I2 prevention and rescue groups, with decreased cell migration following stimulation with S1P prevention and rescue groups after 12 h and 18 h post-scratch. We have demonstrated that I2 treatment reduced fibrosis and modulated the inactivation of LTBPs, TGF-β receptors, SPLs, and the canonical downstream SMAD pathway. Further investigations are warranted in order to fully uncover the potential of utilizing SphK I2 as a novel therapy for corneal fibrosis.

IPF-related new macrophage subpopulations and diagnostic biomarker identification - combine machine learning with single-cell analysis

Idiopathic pulmonary fibrosis (IPF) is a chronic disease of unknown etiology that lacks a specific treatment. In IPF, macrophages play a key regulatory role as a major component of the lung immune system, especially during inflammation and fibrosis. However, our understanding of the cellular heterogeneity and molecular characterization of macrophages in IPF, as well as their relevance in the clinical setting, is relatively limited. In this study, we analyzed in-depth single-cell transcriptome sequencing (scRNA-seq) data from lung tissues of IPF patients, identified macrophage subpopulations in IPF, and probed their molecular characteristics and biological functions. hdWGCNA identified co-expressed gene modules of a subpopulation of IPF-associated macrophages (IPF-MΦ), and probed the IPF-MΦ by a machine-learning approach. hdWGCNA identified a subpopulation of IPF-associated macrophage subpopulations and probed the IPF-MΦ signature gene (IRMG) for its prognostic value, and a prediction model was developed on this basis. In addition, IPF-MΦ was obtained after recluster analysis of macrophages in IPF lung tissues. Coexpressed gene modules of IPF-MΦ were identified by hdWGCNA. Then, a machine learning approach was utilized to reveal the characteristic genes of IPF-MΦ, and a prediction model was built on this basis. In addition, we discovered a type of macrophage unique to IPF lung tissue named ATP5-MΦ. Its characteristic gene encodes a subunit of the mitochondrial ATP synthase complex, which is closely related to oxidative phosphorylation and proton transmembrane transport, suggesting that ATP5-MΦ may have higher ATP synthesis capacity in IPF lung tissue. This study provides new insights into the pathogenesis of IPF and provides a basis for evaluating disease prognosis and predictive medicine in IPF patients.

A Regularized Bayesian Dirichlet-multinomial Regression Model for Integrating Single-cell-level Omics and Patient-level Clinical Study Data

The abundance of various cell types can vary significantly among patients with varying phenotypes and even those with the same phenotype. Recent scientific advancements provide mounting evidence that other clinical variables, such as age, gender, and lifestyle habits, can also influence the abundance of certain cell types. However, current methods for integrating single-cell-level omics data with clinical variables are inadequate. In this study, we propose a regularized Bayesian Dirichlet-multinomial regression framework to investigate the relationship between single-cell RNA sequencing data and patient-level clinical data. Additionally, the model employs a novel hierarchical tree structure to identify such relationships at different cell-type levels. Our model successfully uncovers significant associations between specific cell types and clinical variables across three distinct diseases: pulmonary fibrosis, COVID-19, and non-small cell lung cancer. This integrative analysis provides biological insights and could potentially inform clinical interventions for various diseases.

miR-92a-3p promotes pulmonary fibrosis progression by regulating KLF2-mediated endothelial-to-mesenchymal transition

Pulmonary fibrosis (PF) is a chronic lung disease that has a poor prognosis and a serious impact on the quality of life of patients. Here, we investigated the potential role of miR-92a-3p in PF. The mRNA level of miR-92a-3p was significantly increased in both the lung tissues of bleomycin (BLM)--treated mice and pulmonary microvascular endothelial cells (PMVECs). Overexpressing miR-92a-3p increased the mRNA and protein levels of α‑SMA, vimentin, and Col-1 but downregulated E-cadherin. Additionally, the protein and mRNA expression levels of KLF2 were significantly decreased in the lung tissues of BLM-treated mice, suggesting that KLF2 participated in the progression of BLM-induced PF. Downregulating miR-92a-3p upregulated the expression of KLF2 and inhibited the endothelial-to-mesenchymal transition (EndoMT) process, thus alleviating PF in vivo. Altogether, a miR-92a-3p deficiency could significantly reduce the development of myofibroblasts and ameliorate PF progression.

Protective effects of microbial biosurfactants produced by Bacillus halotolerans and Candida parapsilosis on bleomycin-induced pulmonary fibrosis in mice: Impact of antioxidant, anti-inflammatory and anti-fibrotic properties via TGF-β1/Smad-3 pathway and miRNA-326

Idiopathic pulmonary fibrosis (IPF) is an irreversible disease which considered the most fatal pulmonary fibrosis. Pulmonary toxicity including IPF is the most severe adverse effect of bleomycin, the chemotherapeutic agent. Based on the fact that, exogenous surfactants could induce alveolar stabilization in many lung diseases, the aim of this study was to explore the effects of low cost biosurfactants, surfactin (SUR) and sophorolipids (SLs), against bleomycin-induced pulmonary fibrosis in mice due to their antioxidant, and anti-inflammatory properties. Surfactin and sophorolipids were produced by microbial conversion of frying oil and potato peel wastes using Bacillus halotolerans and Candida parapsilosis respectively. These biosurfactants were identified by FTIR, 1H NMR, and LC-MS/MS spectra. C57BL/6 mice were administered the produced biosurfactants daily at oral dose of 200 mg kg-1 one day after the first bleomycin dose (35 U/kg). We evaluated four study groups: Control, Bleomycin, Bleomycin+SUR, Bleomycin+SLs. After 30 days, lungs from each mouse were sampled for oxidative stress, ELISA, Western blot, histopathological, immunohistochemical analyses. Our results showed that the produced SUR and SLs reduced pulmonary oxidative stress and inflammatory response in the lungs of bleomycin induced mice as they suppressed SOD, CAT, and GST activities also reduced NF-κβ, TNF-α, and CD68 levels. Furthermore, biosurfactants suppressed the expression of TGF-β1, Smad-3, and p-JNK fibrotic signaling pathway in pulmonary tissues. Histologically, SUR and SLs protected against lung ECM deposition caused by bleomycin administration. Biosurfactants produced from microbial sources can inhibit the induced inflammatory and fibrotic responses in bleomycin-induced pulmonary fibrosis.

O-GlcNAc transferase regulates collagen deposition and fibrosis resolution in idiopathic pulmonary fibrosis

Background

Idiopathic pulmonary fibrosis (IPF) is a chronic pulmonary disease that is characterized by an excessive accumulation of extracellular matrix (ECM) proteins (e.g. collagens) in the parenchyma, which ultimately leads to respiratory failure and death. While current therapies exist to slow the progression, no therapies are available to resolve fibrosis.

Methods

We characterized the O-linked N-Acetylglucosamine (O-GlcNAc) transferase (OGT)/O-GlcNAc axis in IPF using single-cell RNA-sequencing (scRNA-seq) data and human lung sections and isolated fibroblasts from IPF and non-IPF donors. The underlying mechanism(s) of IPF were further investigated using multiple experimental models to modulate collagen expression and accumulation by genetically and pharmacologically targeting OGT. Furthermore, we hone in on the transforming growth factor-beta (TGF-β) effector molecule, Smad3, by co-expressing it with OGT to determine if it is modified and its subsequent effect on Smad3 activation.

Results

We found that OGT and O-GlcNAc levels are upregulated in patients with IPF compared to non-IPF. We report that the OGT regulates collagen deposition and fibrosis resolution, which is an evolutionarily conserved process demonstrated across multiple species. Co-expression of OGT and Smad3 showed that Smad3 is O-GlcNAc modified. Blocking OGT activity resulted in decreased phosphorylation at Ser-423/425 of Smad3 attenuating the effects of TGF-β1 induced collagen expression/deposition.

Conclusion

OGT inhibition or knockdown successfully blocked and reversed collagen expression and accumulation, respectively. Smad3 is discovered to be a substrate of OGT and its O-GlcNAc modification(s) directly affects its phosphorylation state. These data identify OGT as a potential target in pulmonary fibrosis resolution, as well as other diseases that might have aberrant ECM/collagen accumulation.

Recent Developments in the Role of Histone Acetylation in Asthma

BACKGROUND

Epigenetic modifications are known to mediate both beneficial and unfavorable effects of environmental exposures on the development and clinical course of asthma. On the molecular level, epigenetic mechanisms participate in multiple aspects of the emerging and ongoing asthma pathology.

SUMMARY

Studies performed in the last several years expand our knowledge on the role of histone acetylation, a classical epigenetic mark, in the regulation of (patho)physiological processes of diverse cells playing a central role in asthma, including those belonging to the immune system (e.g., CD4+ T cells, macrophages) and lung structure (e.g., airway epithelial cells, pulmonary fibroblasts). Those studies demonstrate a number of specific histone acetylation-associated mechanisms and pathways underlying pathological processes characteristic for asthma, as well as report their modification modalities.

KEY MESSAGES

Dietary modulation of histone acetylation levels in the immune system might protect against the development of asthma and other allergies. Interfering with the enzymes controlling the histone acetylation status of structural lung and (local) immune cells might provide future therapeutic options for asthmatics. Despite some methodological obstacles, analysis of the histone acetylation levels might improve asthma diagnostics.

The epithelium takes the stage in asthma and inflammatory bowel diseases

The epithelium is a dynamic barrier and the damage to this epithelial layer governs a variety of complex mechanisms involving not only epithelial cells but all resident tissue constituents, including immune and stroma cells. Traditionally, diseases characterized by a damaged epithelium have been considered "immunological diseases," and research efforts aimed at preventing and treating these diseases have primarily focused on immuno-centric therapeutic strategies, that often fail to halt or reverse the natural progression of the disease. In this review, we intend to focus on specific mechanisms driven by the epithelium that ensure barrier function. We will bring asthma and Inflammatory Bowel Diseases into the spotlight, as we believe that these two diseases serve as pertinent examples of epithelium derived pathologies. Finally, we will argue how targeting the epithelium is emerging as a novel therapeutic strategy that holds promise for addressing these chronic diseases.

Linking NLRP3 inflammasome and pulmonary fibrosis: mechanistic insights and promising therapeutic avenues

Pulmonary fibrosis is a devastating disorder distinguished by redundant inflammation and matrix accumulation in the lung interstitium. The early inflammatory cascade coupled with recurring tissue injury orchestrates a set of events marked by perturbed matrix hemostasis, deposition of matrix proteins, and remodeling in lung tissue. Numerous investigations have corroborated a direct correlation between the NLR family pyrin domain-containing 3 (NLRP3) activation and the development of pulmonary fibrosis. Dysregulated activation of NLRP3 within the pulmonary microenvironment exacerbates inflammation and may incite fibrogenic responses. Nevertheless, the precise mechanisms through which the NLRP3 inflammasome elicits pro-fibrogenic responses remain inadequately defined. Contemporary findings suggest that the pro-fibrotic consequences stemming from NLRP3 signaling primarily hinge on the action of interleukin-1β (IL-1β). IL-1β instigates IL-1 receptor signaling, potentiating the activity of transforming growth factor-beta (TGF-β). This signaling cascade, in turn, exerts influence over various transcription factors, including SNAIL, TWIST, and zinc finger E-box-binding homeobox 1 (ZEB 1/2), which collectively foster myofibroblast activation and consequent lung fibrosis. Here, we have connected the dots to illustrate how the NLRP3 inflammasome orchestrates a multitude of signaling events, including the activation of transcription factors that facilitate myofibroblast activation and subsequent lung remodeling. In addition, we have highlighted the prominent role played by various cells in the formation of myofibroblasts, the primary culprit in lung fibrosis. We also provided a concise overview of various compounds that hold the potential to impede NLRP3 inflammasome signaling, thus offering a promising avenue for the treatment of pulmonary fibrosis.

Emerging delivery approaches for targeted pulmonary fibrosis treatment

Pulmonary fibrosis (PF) is a progressive, and life-threatening interstitial lung disease which causes scarring in the lung parenchyma and thereby affects architecture and functioning of lung. It is an irreversible damage to lung functioning which is related to epithelial cell injury, immense accumulation of immune cells and inflammatory cytokines, and irregular recruitment of extracellular matrix. The inflammatory cytokines trigger the differentiation of fibroblasts into activated fibroblasts, also known as myofibroblasts, which further increase the production and deposition of collagen at the injury sites in the lung. Despite the significant morbidity and mortality associated with PF, there is no available treatment that efficiently and effectively treats the disease by reversing their underlying pathologies. In recent years, many therapeutic regimens, for instance, rho kinase inhibitors, Smad signaling pathway inhibitors, p38, BCL-xL/ BCL-2 and JNK pathway inhibitors, have been found to be potent and effective in treating PF, in preclinical stages. However, due to non-selectivity and non-specificity, the therapeutic molecules also result in toxicity mediated severe side effects. Hence, this review demonstrates recent advances on PF pathology, mechanism and targets related to PF, development of various drug delivery systems based on small molecules, RNAs, oligonucleotides, peptides, antibodies, exosomes, and stem cells for the treatment of PF and the progress of various therapeutic treatments in clinical trials to advance PF treatment.

Mechanistic analysis of Th2-type inflammatory factors in asthma

Background

The main pathological features of asthma are widespread chronic inflammation of the airways and restricted ventilation due to airway remodeling, which involves changes in a range of regulatory pathways. While the role of T helper type 2 (Th2)-related inflammatory factors in this process is known, the detailed understanding of how genes affect protein functions during airway remodeling is still lacking. This study aims to fill this knowledge gap by integrating gene expression data and protein function analysis, providing new scientific insights for a deeper understanding of the mechanisms of airway remodeling and for further development of asthma treatment strategies.

Methods

In this study, the mechanism of Th2-related inflammatory factors in tracheal remodeling was studied through differentially expressed gene (DEG) screening, enrichment analysis, protein-protein interaction (PPI) network construction, machine learning, and the construction of a line graph model.

Results

Our study revealed that S100A14, KRT6A, S100A2, ABCA13, UBE2C, RASSF10, PSCA, PLAT, and TIMP1 may be the key genes for airway remodeling; epithelial-mesenchymal transition (EMT)-related genes GEM, TPM4, SLC6A8, and SNTB1 may be involved in airway remodeling due to asthma; IL6 may affect the occurrence of airway remodeling by binding to UBE2C protein or by regulating GEM genes, respectively; IL6 and IL9 may affect the occurrence of airway remodeling by regulating the downstream Toll-like receptor (TLR) signaling pathway and thus IL6 and IL9 may influence the occurrence of tracheal remodeling by regulating downstream TLR signaling pathways.

Conclusions

This study further mined the asthma gene microarray database through bioinformatics analysis and identified key genes and important pathways affecting airway remodeling in asthma patients, providing new ideas to uncover the mechanism of airway remodeling due to asthma and then seek new therapeutic targets.

Role of GSDM family members in airway epithelial cells of lung diseases: a systematic and comprehensive transcriptomic analysis

Gasdermin (GSDM) family, the key executioners of pyroptosis, play crucial roles in anti-pathogen and anti-tumor immunities, although little is known about the expression of GSDM in lung diseases at single-cell resolution, especially in lung epithelial cells. We comprehensively investigated the transcriptomic profiles of GSDM members in various lung tissues from healthy subjects or patients with different lung diseases at single cell level, e.g., chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), lung adenocarcinoma (LUAD), or systemic sclerosis (SSC). The expression of GSDM members varied among pulmonary cell types (immune cells, structural cells, and especially epithelial cells) and even across lung diseases. Regarding disease-associated specificities, we found that GSDMC or GSDMD altered significantly in ciliated epithelia of COPD or LUAD, GSDMD in mucous, club, and basal cells of LUAD and GSDMC in mucous epithelia of para-tumor tissue, as compared with the corresponding epithelia of other diseases. The phenomic specificity of GSDM in lung cancer subtypes was noticed by comparing with 15 non-pulmonary cancers and para-cancer samples. GSDM family gene expression changes were also observed in different lung epithelial cell lines (e.g., HBE, A549, H1299, SPC-1, or H460) in responses to external challenges, including lipopolysaccharide (LPS), lysophosphatidylcholine (lysoPC), cigarette smoking extract (CSE), cholesterol, and AR2 inhibitor at various doses or durations. GSDMA is rarely expressed in those cell lines, while GSDMB and GSDMC are significantly upregulated in human lung epithelia. Our data indicated that the heterogeneity of GSDM member expression exists at different cells, pathologic conditions, challenges, probably dependent upon cell biological phenomes, functions, and behaviors, upon cellular responses to external changes, and the nature and severity of lung disease. Thus, the deep exploration of GSDM phenomes may provide new insights into understanding the single-cell roles in the tissue, regulatory roles of the GSDM family in the pathogenesis, and potential values of biomarker identification and development.

MiR-326-mediated overexpression of NFIB offsets TGF-β induced epithelial to mesenchymal transition and reverses lung fibrosis

Idiopathic Pulmonary Fibrosis (IPF) is a progressively fatal and incurable disease characterized by the loss of alveolar structures, increased epithelial-mesenchymal transition (EMT), and aberrant tissue repair. In this study, we investigated the role of Nuclear Factor I-B (NFIB), a transcription factor critical for lung development and maturation, in IPF. Using both human lung tissue samples from patients with IPF, and a mouse model of lung fibrosis induced by bleomycin, we showed that there was a significant reduction of NFIB both in the lungs of patients and mice with IPF. Furthermore, our in vitro experiments using cultured human lung cells demonstrated that the loss of NFIB was associated with the induction of EMT by transforming growth factor beta (TGF-β). Knockdown of NFIB promoted EMT, while overexpression of NFIB suppressed EMT and attenuated the severity of bleomycin-induced lung fibrosis in mice. Mechanistically, we identified post-translational regulation of NFIB by miR-326, a miRNA with anti-fibrotic effects that is diminished in IPF. Specifically, we showed that miR-326 stabilized and increased the expression of NFIB through its 3'UTR target sites for Human antigen R (HuR). Moreover, treatment of mice with either NFIB plasmid or miR-326 reversed airway collagen deposition and fibrosis. In conclusion, our study emphasizes the critical role of NFIB in lung development and maturation, and its reduction in IPF leading to EMT and loss of alveolar structures. Our study highlights the potential of miR-326 as a therapeutic intervention for IPF. The schema shows the role of NFIB in maintaining the normal epithelial cell characteristics in the lungs and how its reduction leads to a shift towards mesenchymal cell-like features and pulmonary fibrosis. A In normal lungs, NFIB is expressed abundantly in the epithelial cells, which helps in maintaining their shape, cell polarity and adhesion molecules. However, when the lungs are exposed to factors that induce pulmonary fibrosis, such as bleomycin, or TGF-β, the epithelial cells undergo epithelial to mesenchymal transition (EMT), which leads to a decrease in NFIB. B The mesenchymal cells that arise from EMT appear as spindle-shaped with loss of cell junctions, increased cell migration, loss of polarity and expression of markers associated with mesenchymal cells/fibroblasts. C We designed a therapeutic approach that involves exogenous administration of NFIB in the form of overexpression plasmid or microRNA-326. This therapeutic approach decreases the mesenchymal cell phenotype and restores the epithelial cell phenotype, thus preventing the development or progression of pulmonary fibrosis.

P2X7 accelerate tissue fibrosis via metalloproteinase 8-dependent macrophage infiltration in a murine model of unilateral ureteral obstruction

Renal fibrosis is tightly associated with chronic kidney disease, irrespective of the underlying pathogenesis. We previously demonstrated mild antifibrotic effects of targeting the P2X7 receptor in a pyelonephritis model. Reduced P2X7 R-activation elevated the neutrophil-to-macrophage ratio, resulting in less matrix accumulation without affecting the initial tissue healing. Here, we test if this P2X7 R-dependent modification of matrix accumulation also applies to a noninfectious fibrosis model of unilateral ureteral obstruction (7dUUO) and whether the response is gender-dependent. We found that P2X7 -/- mice show reduced fibrosis compared to wild type after 7dUUO: the effect was most pronounced in females, with a 55% decrease in collagen deposition after 7dUUO (p < 0.0068). P2X7 R deficiency did not affect early fibrosis markers (TGF-β, α-SMA) or the renal infiltration of neutrophils. However, a UUO-induced increase in macrophages was observed in wildtypes only (p < 0.001), leaving the P2X7 -/- mice with ≈50% fewer CD68+ cells in the renal cortex (p = 0.018). In males, 7dUUO triggered an increase in diffusely interstitial scattering of the profibrotic, macrophage-attracting metalloproteinase MMP8 and showed significantly lower MMP8 tissue expression in both male and female P2X7 -/- mice (p < 0.0008). Thus, the P2X7 R is advocated as a late-stage fibrosis moderator by reducing neutrophil-dependent interstitial MMP8 release, resulting in less macrophage infiltration and reduced matrix accumulation.

The mechanisms and therapeutic potential of long noncoding RNA NEAT1 in fibrosis

Fibrosis is the excess deposition of extracellular matrix involved in the pathogenesis of chronic diseases and finally leads to the disruption of tissue architecture and failure of organ function. Long noncoding RNAs (lncRNAs) are a class of RNAs with lengths greater than 200 nucleotides and do not code proteins, which regulate gene expression at multiple levels. Nuclear-enriched abundant transcript 1 (NEAT1) is a long noncoding RNA that is widely expressed in mammalian cells and known as essential architectural scaffold for the formation of paraspeckles. Recently, the accumulating studies demonstrated that lncRNA NEAT1 was remarkable upregulated in the development of fibrosis in different organs, such as liver fibrosis, renal fibrosis, cardiac fibrosis, and lung fibrosis. More importantly, knockdown of NEAT1 remarkably alleviated fibrosis in vitro and in vivo. In this review, we summarized current studies of NEAT1 in fibrosis and hopefully aid in a better understanding of the mechanisms of fibrosis and the potential of NEAT1 as novel therapeutic target for fibrosis.

Single-Cell RNA Sequencing Provides New Insights into Therapeutic Roles of Thyroid Hormone in Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive fatal interstitial lung disease without an effective cure. Herein, we explore the role of 3,5,3'-triiodothyronine (T3) administration on lung alveolar regeneration and fibrosis at the single-cell level. T3 supplementation significantly altered the gene expression in fibrotic lung tissues. Immune cells were rapidly recruited into the lung after the injury; there were much more M2 macrophages than M1 macrophages in the lungs of bleomycin-treated mice; and M1 macrophages increased slightly, whereas M2 macrophages were significantly reduced after T3 treatment. T3 enhanced the resolution of pulmonary fibrosis by promoting the differentiation of Krt8+ transitional alveolar type II epithelial cells into alveolar type I epithelial cells and inhibiting fibroblast activation and extracellular matrix production potentially by regulation of Nr2f2. In addition, T3 regulated the crosstalk of macrophages with fibroblasts, and the Pros1-Axl signaling axis significantly facilitated the attenuation of fibrosis. The findings demonstrate that administration of a thyroid hormone promotes alveolar regeneration and resolves fibrosis mainly by regulation of the cellular state and cell-cell communication of alveolar epithelial cells, macrophages, and fibroblasts in mouse lungs in comprehensive ways.

Adiponectin inhibits TGF-β1-induced skin fibroblast proliferation and phenotype transformation via the p38 MAPK signaling pathway

The aim of this study was to investigate the effects of adiponectin (APN) on the proliferation and phenotypic transformation of human skin fibroblasts (HSFs) induced by TGF-β1. Primary fibroblast cultures were collected from prepuce surgery, and the cell viability and proliferative activity of HSFs were detected by Cell Counting Kit-8 and EdU assays. In addition, cell migration was detected by Transwell assay. The protein levels of related genes in HSF were detected by Western blotting. The results showed that the proliferation and migration abilities of HSF in the TGF-β1 group were significantly improved, and the relative protein expression levels of PCNA, α-SMA, and Collagen I in the TGF-β1 group were greatly increased. Furthermore, TGF-β1 stimulated the phosphorylation of p38 in HSF, while APN pretreatment significantly inhibited the TGF-β1-induced phosphorylation of p38. Additionally, blocking the p38 MAPK signaling pathway relieved the injury in the HSF induced by TGF-β1 and enhanced the therapeutic effect of APN in the TGF-β1-treated HSF. In conclusion, APN inhibits TGF-β1-induced HSF proliferation and myofibroblast phenotypic transformation by activating the p38 MAPK signaling pathway. APN is expected to become a potential target for preventing and treating skin fibrosis and pathological scars.

Epithelial-Mesenchymal Transition Mechanisms in Chronic Airway Diseases: A Common Process to Target?

Epithelial-to-mesenchymal transition (EMT) is a reversible process, in which epithelial cells lose their epithelial traits and acquire a mesenchymal phenotype. This transformation has been described in different lung diseases, such as lung cancer, interstitial lung diseases, asthma, chronic obstructive pulmonary disease and other muco-obstructive lung diseases, such as cystic fibrosis and non-cystic fibrosis bronchiectasis. The exaggerated chronic inflammation typical of these pulmonary diseases can induce molecular reprogramming with subsequent self-sustaining aberrant and excessive profibrotic tissue repair. Over time this process leads to structural changes with progressive organ dysfunction and lung function impairment. Although having common signalling pathways, specific triggers and regulation mechanisms might be present in each disease. This review aims to describe the various mechanisms associated with fibrotic changes and airway remodelling involved in chronic airway diseases. Having better knowledge of the mechanisms underlying the EMT process may help us to identify specific targets and thus lead to the development of novel therapeutic strategies to prevent or limit the onset of irreversible structural changes.

Harnessing the Therapeutic Potential of Stem Cells in the Management of Chronic Obstructive Pulmonary Disease: A Comprehensive Review

Chronic obstructive pulmonary disease (COPD) is a prevalent and debilitating respiratory condition with limited treatment options. Stem cell therapy has emerged as a promising approach for COPD management due to its regenerative and immunomodulatory properties. This review article aims to comprehensively explore the therapeutic potential of stem cells in COPD management. The introduction provides background on COPD, highlighting its impact on health and the need for novel therapies. The different types of stem cells relevant to COPD, including embryonic stem cells, adult stem cells, and induced pluripotent stem cells, are described along with their properties and characteristics. The pathogenesis of COPD is discussed, emphasizing the key mechanisms involved in disease development and progression. Subsequently, the role of stem cells in tissue repair, regeneration, and immunomodulation is examined, highlighting their ability to address specific pathological processes in COPD. Mechanisms of action, such as paracrine signaling, immunomodulation, anti-inflammatory effects, and tissue regeneration, are explored. The interaction between stem cells and the host environment, which promotes lung repair, is also discussed. Challenges in stem cell therapy for COPD, including optimal cell sources, delivery methods, safety, and efficacy, are identified. Regulatory considerations and the importance of standardization are emphasized. Potential strategies for optimizing the therapeutic potential of stem cells in COPD management, such as combination therapies and preconditioning techniques, are outlined. Emerging trends and future directions are highlighted, including advanced cell engineering and patient-specific induced pluripotent stem cells. In conclusion, stem cell therapy holds significant promise for COPD management, addressing the limitations of current treatments. Continued research and development are necessary to overcome challenges, optimize therapies, and realize stem cells' full potential in improving the lives of patients with COPD.

Molecular and immune signatures, and pathological trajectories of fatal COVID-19 lungs defined by in situ spatial single-cell transcriptome analysis

Despite intensive studies during the last 3 years, the pathology and underlying molecular mechanism of coronavirus disease 2019 (COVID-19) remain poorly defined. In this study, we investigated the spatial single-cell molecular and cellular features of postmortem COVID-19 lung tissues using in situ sequencing (ISS). We detected 10 414 863 transcripts of 221 genes in whole-slide tissues and segmented them into 1 719 459 cells that were mapped to 18 major parenchymal and immune cell types, all of which were infected by SARS-CoV-2. Compared with the non-COVID-19 control, COVID-19 lungs exhibited reduced alveolar cells (ACs) and increased innate and adaptive immune cells. We also identified 19 differentially expressed genes in both infected and uninfected cells across the tissues, which reflected the altered cellular compositions. Spatial analysis of local infection rates revealed regions with high infection rates that were correlated with high cell densities (HIHD). The HIHD regions expressed high levels of SARS-CoV-2 entry-related factors including ACE2, FURIN, TMPRSS2 and NRP1, and co-localized with organizing pneumonia (OP) and lymphocytic and immune infiltration, which exhibited increased ACs and fibroblasts but decreased vascular endothelial cells and epithelial cells, mirroring the tissue damage and wound healing processes. Sparse nonnegative matrix factorization (SNMF) analysis of niche features identified seven signatures that captured structure and immune niches in COVID-19 tissues. Trajectory inference based on immune niche signatures defined two pathological routes. Trajectory A primarily progressed with increased NK cells and granulocytes, likely reflecting the complication of microbial infections. Trajectory B was marked by increased HIHD and OP, possibly accounting for the increased immune infiltration. The OP regions were marked by high numbers of fibroblasts expressing extremely high levels of COL1A1 and COL1A2. Examination of single-cell RNA-seq data (scRNA-seq) from COVID-19 lung tissues and idiopathic pulmonary fibrosis (IPF) identified similar cell populations consisting mainly of myofibroblasts. Immunofluorescence staining revealed the activation of IL6-STAT3 and TGF-β-SMAD2/3 pathways in these cells, likely mediating the upregulation of COL1A1 and COL1A2 and excessive fibrosis in the lung tissues. Together, this study provides a spatial single-cell atlas of cellular and molecular signatures of fatal COVID-19 lungs, which reveals the complex spatial cellular heterogeneity, organization, and interactions that characterized the COVID-19 lung pathology.

Exhaled breath condensate identifies metabolic dysregulation in patients with radiation-induced lung injury

Radiation-induced lung injury (RILI) is a consequence of therapeutic thoracic irradiation (TR) for many cancers, and there are no FDA-approved curative strategies. Studies report that 80% of patients who undergo TR will have CT-detectable interstitial lung abnormalities, and strategies to limit the risk of RILI may make radiotherapy less effective at treating cancer. Our lab and others have reported that lung tissue from patients with idiopathic pulmonary fibrosis (IPF) exhibits metabolic defects including increased glycolysis and lactate production. In this pilot study, we hypothesized that patients with radiation-induced lung damage will exhibit distinct changes in lung metabolism that may be associated with the incidence of fibrosis. Using liquid chromatography/tandem mass spectrometry to identify metabolic compounds, we analyzed exhaled breath condensate (EBC) in subjects with CT-confirmed lung lesions after TR for lung cancer, compared with healthy subjects, smokers, and cancer patients who had not yet received TR. The lung metabolomic profile of the irradiated group was significantly different from the three nonirradiated control groups, highlighted by increased levels of lactate. Pathway enrichment analysis revealed that EBC from the case patients exhibited concurrent alterations in lipid, amino acid, and carbohydrate energy metabolism associated with the energy-producing tricarboxylic acid (TCA) cycle. Radiation-induced glycolysis and diversion of lactate to the extracellular space suggests that pyruvate, a precursor metabolite, converts to lactate rather than acetyl-CoA, which contributes to the TCA cycle. This TCA cycle deficiency may be compensated by these alternate energy sources to meet the metabolic demands of chronic wound repair. Using an "omics" approach to probe lung disease in a noninvasive manner could inform future mechanistic investigations and the development of novel therapeutic targets.NEW & NOTEWORTHY We report that exhaled breath condensate (EBC) identifies cellular metabolic dysregulation in patients with radiation-induced lung injury. In this pilot study, untargeted metabolomics revealed a striking metabolic signature in EBC from patients with radiation-induced lung fibrosis compared to patients with lung cancer, at-risk smokers, and healthy volunteers. Patients with radiation-induced fibrosis exhibit specific changes in tricarboxylic acid (TCA) cycle energy metabolism that may be required to support the increased energy demands of fibroproliferation.

Lung mesenchymal cells from patients with COVID-19 driven lung fibrosis: Several features with CTD-ILD derived cells but with higher response to fibrogenic signals and might be more pro-inflammatory

A subset of severe COVID19 patients develop pulmonary fibrosis, but the pathophysiology of this complication is still unclear. We previously described the possibility to isolate lung mesenchymal cells (LMC) by culturing broncho-alveolar lavage (BAL) cells from patients with pulmonary fibrosis or chronic lung allograft dysfunction. Aim of this study was to investigate the possibility to isolate and characterize LMC from BAL of patients that, two months after discharge for severe COVID19, show CT signs of post-COVID19 fibrosis (Post-COVID) and in some cases has been considered transplant indication. Results were compared with those from BAL of patients with collagen tissue disease-associated interstitial fibrosis (CTD-ILD). BAL fluid levels of TGFβ, VEGF, TIMP2, RANTES, IL6, IL8, and PAI1 were assessed. LMC were cultured and expanded, phenotyped by flow cytometry, and tested for osteogenic and adipogenic differentiation. Finally, we tested immunomodulatory and proliferative capabilities, collagen I production + /- TGF-beta stimulation. BAL cytokine and growth factor levels were comparable in the two groups. Efficiency of isolation from BAL was 100% in post-COVID compared to 63% in CTD-ILD. LMC from post-COVID were positive for CD105, CD73, CD90, and negative for CD45, CD34, CD19 and HLA-DR as in CTD-ILD samples. Post-COVID LMC displayed higher collagen production with respect to CTD-ILD LMC. Immunomodulatory capacity towards lymphocytes was very low, while Post-COVID LMC significantly upregulated pro-inflammatory cytokine production by healthy PBMCs. Our preliminary data suggest that LMC from post-COVID19 fibrosis patients share several features with CTD-ILD ones but might have a higher response to fibrogenic signals and pro-inflammatory profile.

Potentiation of Sphingolipids and TGF-β in the human corneal stroma reveals intricate signaling pathway crosstalks

Corneal haze brought on by fibrosis due to insult can lead to partial or complete vision loss. Currently, corneal transplantation is the gold standard for treating severe corneal fibrosis, which comes with the risk of rejection and the issue of donor tissue shortages. Sphingolipids (SPLs) are known to be associated with fibrosis in various tissues and organs, including the cornea. We previously reported that SPLs are tightly related to Transforming Growth Factor β (TGF-β) signaling and corneal fibrogenesis. This study aimed to elucidate the interplay of SPLs, specifically sphingosine-1-phosphate (S1P) signaling, and its' interactions with TGF-β signaling through detailed analyses of the corresponding downstream signaling targets in the context of corneal fibrosis, in vitro. Healthy human corneal fibroblasts (HCFs) were isolated, plated on polycarbonate membranes, and stimulated with a stable Vitamin C derivative. The 3D constructs were treated with either 5 μM sphingosine-1-phosphate (S1P), 5 μM SPHK I₂ (I₂; inhibitor of sphingosine kinase 1, one of the two enzymes responsible for generating S1P in mammalian cells), 0.1 ng/mL TGF-β1, or 0.1 ng/mL TGF-β3. Cultures with control medium-only served as controls. All 3D constructs were examined for protein expression of fibrotic markers, SPLs, TGF-βs, and relevant downstream signaling pathways. This data revealed no significant changes in any LTBP (latent TGF-β binding proteins) expression when stimulated with S1P or I₂. However, LTBP1 was significantly upregulated via stimulation of TGF-β1 and TGF-β3, whereas LTBP2 was significantly upregulated only with TGF-β3 stimulation. Significant downregulation of TGF-β receptor II (TGF-βRII) following S1P stimulation but significant upregulation following I₂ stimulation was observed. Following TGF-β1, S1P, and I₂ stimulation, phospho-SMAD2 (pSMAD2) was significantly downregulated. Furthermore, I₂ stimulation led to significant downregulation of SMAD4. Adhesion/proliferation/transcription regulation targets, SRC, FAK, and pERK 1/2 were all significantly downregulated by exogenous S1P, whereas I₂ only significantly downregulated FAK. Exogenous TGF-β3 caused significant upregulation of AKT. Interestingly, both I₂ and TGF-β3 caused significant downregulation of JNK expression. Lastly, TGF-β1 led to significant upregulation of sphingosine kinase 1 (SphK1) and sphingosine-1-phosphate receptor 3 (S1PR3), whereas TGF-β3 caused significant upregulation of only SphK1. Together with previously published work from our group and others, S1P inhibition exhibits great potential as an efficacious anti-fibrotic modality in human corneal stromal ECM. The current findings shed further light on a very complex and rather incompletely investigated mechanism, and cement the intricate crosstalk between SPLs and TGF-β in corneal fibrogenesis. Future studies will dictate the potential of utilizing SPLs/TGF-β signaling modulators as novel therapeutics in corneal fibrosis.

Pulmonary 5-HT2B receptor expression in fibrotic interstitial lung diseases

Pulmonary fibrosis is a severe condition in interstitial lung diseases (ILD) such as idiopathic pulmonary fibrosis (IPF) and systemic sclerosis-ILD, where the underlying mechanism is not well defined and with no curative treatments available. Serotonin (5-HT) signaling via the 5-HT_2B receptor has been recognized as a promising preclinical target for fibrosis. Despite this, the involvement of the 5-HT_2B receptor in fibrotic ILD is widely unexplored. This work highlights the spatial pulmonary distribution of the 5-HT_2B receptor in patients with IPF and systemic sclerosis-ILD. We show that the 5-HT_2B receptor is located in typical pathological structures e.g. honeycomb cysts and weakly in fibroblast foci. Together with immunohistochemistry and immunofluorescence stainings of patient derived distal lung tissues, we identified cell targets for 5-HT_2B receptor interference in type II alveolar epithelial cells, endothelial cells and M2 macrophages. Our results emphasize the role of 5-HT_2B receptor as a target in lung fibrosis, warranting further consideration in targeting fibrotic ILDs.

Matrix Metalloproteinases in Chronic Obstructive Pulmonary Disease

Matrix metalloproteinases (MMPs) are proteolytic enzymes that degrade proteins of the extracellular matrix and the basement membrane. Thus, these enzymes regulate airway remodeling, which is a major pathological feature of chronic obstructive pulmonary disease (COPD). Furthermore, proteolytic destruction in the lungs may lead to loss of elastin and the development of emphysema, which is associated with poor lung function in COPD patients. In this literature review, we describe and appraise evidence from the recent literature regarding the role of different MMPs in COPD, as well as how their activity is regulated by specific tissue inhibitors. Considering the importance of MMPs in COPD pathogenesis, we also discuss MMPs as potential targets for therapeutic intervention in COPD and present evidence from recent clinical trials in this regard.

The uPA/uPAR System Orchestrates the Inflammatory Response, Vascular Homeostasis, and Immune System in Fibrosis Progression

Fibrotic diseases, such as systemic sclerosis (SSc), idiopathic pulmonary fibrosis, renal fibrosis and liver cirrhosis are characterized by tissue overgrowth due to excessive extracellular matrix (ECM) deposition. Fibrosis progression is caused by ECM overproduction and the inhibition of ECM degradation due to several events, including inflammation, vascular endothelial dysfunction, and immune abnormalities. Recently, it has been reported that urokinase plasminogen activator (uPA) and its receptor (uPAR), known to be fibrinolytic factors, orchestrate the inflammatory response, vascular homeostasis, and immune homeostasis system. The uPA/uPAR system may show promise as a potential therapeutic target for fibrotic diseases. This review considers the role of the uPA/uPAR system in the progression of fibrotic diseases.

Multi-Step Extracellular Matrix Remodelling and Stiffening in the Development of Idiopathic Pulmonary Fibrosis

The extracellular matrix (ECM) of the lung is a filamentous network composed mainly of collagens, elastin, and proteoglycans that provides structural and physical support to its populating cells. Proliferation, migration and overall behaviour of those cells is greatly determined by micromechanical queues provided by the ECM. Lung fibrosis displays an aberrant increased deposition of ECM which likely changes filament organization and stiffens the ECM, thus upregulating the profibrotic profile of pulmonary cells. We have previously used AFM to assess changes in the Young's Modulus (E) of the ECM in the lung. Here, we perform further ECM topographical, mechanical and viscoelastic analysis at the micro- and nano-scale throughout fibrosis development. Furthermore, we provide nanoscale correlations between topographical and elastic properties of the ECM fibres. Firstly, we identify a softening of the ECM after rats are instilled with media associated with recovery of mechanical homeostasis, which is hindered in bleomycin-instilled lungs. Moreover, we find opposite correlations between fibre stiffness and roughness in PBS- vs bleomycin-treated lung. Our findings suggest that changes in ECM nanoscale organization take place at different stages of fibrosis, with the potential to help identify pharmacological targets to hinder its progression.

Oxy210, a Semi-Synthetic Oxysterol, Inhibits Profibrotic Signaling in Cellular Models of Lung and Kidney Fibrosis

Oxy210, a semi-synthetic oxysterol derivative, displays cell-selective inhibition of Hedgehog (Hh) and transforming growth factor beta (TGF-β) signaling in epithelial cells, fibroblasts, and macrophages as well as antifibrotic and anti-inflammatory efficacy in models of liver fibrosis. In the present report, we examine the effects of Oxy210 in cellular models of lung and kidney fibrosis, such as human lung fibroblast cell lines IMR-90, derived from healthy lung tissue, and LL97A, derived from an idiopathic pulmonary fibrosis (IPF) patient. In addition, we examine the effects of Oxy210 in primary human renal fibroblasts, pericytes, mesangial cells, and renal tubular epithelial cells, known for their involvement in chronic kidney disease (CKD) and kidney fibrosis. We demonstrate in fibroblasts that the expression of several profibrotic TGF-β target genes, including fibronectin (FN), collagen 1A1 (COL1A1), and connective tissue growth factor (CTGF) are inhibited by Oxy210, both at the basal level and following TGF-β stimulation in a statistically significant manner. The inhibition of COL1A1 gene expression translated directly to significantly reduced COL1A1 protein expression. In human primary small airway epithelial cells (HSAECs) and renal tubular epithelial cells, Oxy210 significantly inhibited TGF-β target gene expression associated with epithelial-mesenchymal transition (EMT). Oxy210 also inhibited the proliferation of fibroblasts, pericytes, and mesangial cells in a dose-dependent and statistically significant manner.

Piceatannol-mediated JAK2/STAT3 signaling pathway inhibition contributes to the alleviation of oxidative injury and collagen synthesis during pulmonary fibrosis

Pulmonary fibrosis (PF) is characterized by oxidative injury and excessive collagen synthesis in lung fibroblasts, causing impaired pulmonary function and chronic lung injury. Piceatannol, a dietary polyphenol, possesses vital pharmacological effects in metabolic disorders, cancers, cardiovascular disease and infectious disease; however, its role in PF is still not completely elucidated. Mice (8 to 10 weeks old) were administered bleomycin (BLM) intratracheally (2 U/kg) to establish an in vivo PF model. Murine primary lung fibroblasts were isolated and stimulated with TGF-β (10 ng/mL) for 48 h to induce its activation. Meanwhile, mice or primary lung fibroblasts were treated with different doses of piceatannol to observe its protective roles. Pulmonary function and arterial blood gas were detected to assess pulmonary physiological status. Collagen deposition and the mRNA levels of profibrotic genes were determined by H&E staining and RT-PCR. Meanwhile, the protein and mRNA markers, as well as end-product of oxidative stress were detected in vivo and in vitro. The results showed that pulmonary function was significantly impaired in BLM-induced mice, accompanied by elevated oxidative stress and excessive collagen synthesis. Piceatannol significantly improved pulmonary function and decreased oxidative injury as well as collagen synthesis in mice with PF. Mechanically, piceatannol treatment significantly inhibited the activation of JAK2/STAT3 signaling pathway in BLM-induced mice and TGF-β-induced lung fibroblasts. Additional findings also demonstrated that coumermycin A1 (C-A1), an agonist of JAK2, could abolish the effects of piceatannol on TGF-β-induced lung fibroblasts and reactivated the phosphorylation STAT3. Taken together, our study demonstrated that piceatannol could protect against oxidative injury and collagen synthesis during PF in a JAK2/STAT3 signaling pathway-dependent manner.