MUC4 is overexpressed in idiopathic pulmonary fibrosis and collaborates with transforming growth factor β inducing fibrotic responses

Phosphodiesterase 4 is overexpressed in human keloids and its inhibition reduces fibroblast activation and skin fibrosis

There is a pressing medical need for improved treatments in skin fibrosis including keloids and hypertrophic scars (HTS). This study aimed to characterize the role of phosphodiesterase 4 (PDE4), specifically PDE4B in fibrotic skin remodeling in vitro and in vivo. In vitro, effects of PDE4A-D (Roflumilast) or PDE4B (siRNA) inhibition on TGFβ1-induced myofibroblast differentiation and dedifferentiation were studied in normal (NHDF) and keloid (KF) human dermal fibroblasts. In vivo, the role of PDE4 on HOCl-induced skin fibrosis in mice was addressed in preventive and therapeutic protocols. PDE4B (mRNA, protein) was increased in Keloid > HTS compared to healthy skin and in TGFβ-stimulated NHDF and KF. In Keloid > HTS, collagen Iα1, αSMA, TGFβ1 and NOX4 mRNA were all elevated compared to healthy skin confirming skin fibrosis. In vitro, inhibition of PDE4A-D and PDE4B similarly prevented TGFβ1-induced Smad3 and ERK1/2 phosphorylation and myofibroblast differentiation, elevated NOX4 protein and proliferation in NHDF. PDE4A-D inhibition enabled myofibroblast dedifferentiation and curbed TGFβ1-induced reactive oxygen species and fibroblast senescence. In KF PDE4A-D inhibition restrained TGFβ1-induced Smad3 and ERK1/2 phosphorylation, myofibroblast differentiation and senescence. Mechanistically, PDE4A-D inhibition rescued from TGFβ1-induced loss in PPM1A, a Smad3 phosphatase. In vivo, PDE4 inhibition mitigated HOCl-induced skin fibrosis in mice in preventive and therapeutic protocols. The current study provides novel evidence evolving rationale for PDE4 inhibitors in skin fibrosis (including keloids and HTS) and delivered evidence for a functional role of PDE4B in this fibrotic condition.

Targeting IL-11 to reduce fibrocyte circulation and lung accumulation in animal models of pulmonary hypertension-associated lung fibrosis

BACKGROUND AND PURPOSE

IL-11 is a member of the IL-6 family of cytokine initially considered as haematopoietic and cytoprotective factor. Recent evidence indicates that IL-11 promotes lung fibrosis and pulmonary hypertension in animal models and is elevated in lung tissue of patients with pulmonary fibrosis and pulmonary hypertension. Fibrocytes are bone marrow-derived circulating cells that participate in lung fibrosis and pulmonary hypertension, but the role of IL-11 on fibrocytes is unknown. We investigated the role of IL-11 system on fibrocyte activation in different in vitro and in vivo models of lung fibrosis associated with pulmonary hypertension.

EXPERIMENTAL APPROACH

Human fibrocytes were isolated from peripheral blood of six healthy donors. Recombinant human (rh)-IL-11 and soluble rh-IL-11 receptor, α subunit (IL-11Rα) were used to stimulated fibrocytes in vitro to measure:- cell migration in a chemotactic migration chamber, fibrocyte to endothelial cell adhesion in a microscope-flow chamber and fibrocyte to myofibroblast transition. Mouse lung fibrosis and pulmonary hypertension was induced using either IL-11 (s.c.) or bleomycin (intra-tracheal), while in the rat monocrotaline (intra-tracheal) was used. In vivo siRNA-IL-11 was administered to suppress IL-11 in vivo.

KEY RESULTS

RhIL-11 and soluble rhIL-11Rα promote fibrocyte migration, endothelial cell adhesion and myofibroblast transition. Subcutaneous (s.c.) IL-11 infusion elevates blood, bronchoalveolar and lung tissue fibrocytes. SiRNA-IL-11 transfection in bleomycin and monocrotaline animal models reduces blood and lung tissue fibrocytes and reduces serum CXCL12 and CXCL12/CXCR4 lung expression.

CONCLUSION AND IMPLICATIONS

Targeting IL-11 reduces fibrocyte circulation and lung accumulation in animal models of pulmonary hypertension-associated lung fibrosis.

8-Oxoguanine DNA glycosylase protects cells from senescence via the p53-p21 pathway

Cellular senescence is an important factor leading to pulmonary fibrosis. Deficiency of 8-oxoguanine DNA glycosylase (OGG1) in mice leads to alleviation of bleomycin (BLM)-induced mouse pulmonary fibrosis, and inhibition of the OGG1 enzyme reduces the epithelial mesenchymal transition (EMT) in lung cells. In the present study, we find decreased expression of OGG1 in aged mice and BLM-induced cell senescence. In addition, a decrease in OGG1 expression results in cell senescence, such as increases in the percentage of SA-β-gal-positive cells, and in the p21 and p-H2AX protein levels in response to BLM in lung cells. Furthermore, OGG1 promotes cell transformation in A549 cells in the presence of BLM. We also find that OGG1 siRNA impedes cell cycle progression and inhibits the levels of telomerase reverse transcriptase (TERT) and LaminB1 in BLM-treated lung cells. The increase in OGG1 expression results in the opposite phenomenon. The mRNA levels of senescence-associated secretory phenotype (SASP) components, including IL-1α, IL-1β, IL-6, IL-8, CXCL1/CXCL2, and MMP-3, in the absence of OGG1 are obviously increased in A549 cells treated with BLM. Interestingly, we demonstrate that OGG1 binds to p53 to inhibit the activation of p53 and that silencing of p53 reverses the inhibition of OGG1 on senescence in lung cells. Additionally, the augmented cell senescence is shown in vivo in OGG1-deficient mice. Overall, we provide direct evidence in vivo and in vitro that OGG1 plays an important role in protecting tissue cells against aging associated with the p53 pathway.

Study on Potential Differentially Expressed Genes in Idiopathic Pulmonary Fibrosis by Bioinformatics and Next-Generation Sequencing Data Analysis

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease with reduced quality of life and earlier mortality, but its pathogenesis and key genes are still unclear. In this investigation, bioinformatics was used to deeply analyze the pathogenesis of IPF and related key genes, so as to investigate the potential molecular pathogenesis of IPF and provide guidance for clinical treatment. Next-generation sequencing dataset GSE213001 was obtained from Gene Expression Omnibus (GEO), and the differentially expressed genes (DEGs) were identified between IPF and normal control group. The DEGs between IPF and normal control group were screened with the DESeq2 package of R language. The Gene Ontology (GO) and REACTOME pathway enrichment analyses of the DEGs were performed. Using the g:Profiler, the function and pathway enrichment analyses of DEGs were performed. Then, a protein-protein interaction (PPI) network was constructed via the Integrated Interactions Database (IID) database. Cytoscape with Network Analyzer was used to identify the hub genes. miRNet and NetworkAnalyst databaseswereused to construct the targeted microRNAs (miRNAs), transcription factors (TFs), and small drug molecules. Finally, receiver operating characteristic (ROC) curve analysis was used to validate the hub genes. A total of 958 DEGs were screened out in this study, including 479 up regulated genes and 479 down regulated genes. Most of the DEGs were significantly enriched in response to stimulus, GPCR ligand binding, microtubule-based process, and defective GALNT3 causes HFTC. In combination with the results of the PPI network, miRNA-hub gene regulatory network and TF-hub gene regulatory network, hub genes including LRRK2, BMI1, EBP, MNDA, KBTBD7, KRT15, OTX1, TEKT4, SPAG8, and EFHC2 were selected. Cyclothiazide and rotigotinethe are predicted small drug molecules for IPF treatment. Our findings will contribute to identification of potential biomarkers and novel strategies for the treatment of IPF, and provide a novel strategy for clinical therapy.

Targeting IL-11 system as a treatment of pulmonary arterial hypertension

IL-11 is linked to fibrotic diseases, but its role in pulmonary hypertension is unclear. We examined IL-11's involvement in idiopathic pulmonary arterial hypertension (iPAH). Using samples from control (n = 20) and iPAH (n = 6) subjects, we assessed IL-11 and IL-11Rα expression and localization through RT-qPCR, ELISA, immunohistochemistry, and immunofluorescence. A monocrotaline-induced PAH model helped evaluate the impact of siRNA-IL-11 on pulmonary artery remodeling and PH. The effects of recombinant human IL-11 and IL-11Rα on human pulmonary artery smooth muscle cell (HPASMC) proliferation, pulmonary artery endothelial cell (HPAEC) mesenchymal transition, monocyte interactions, endothelial tube formation, and precision cut lung slice (PCLS) pulmonary artery remodeling and contraction were evaluated. IL-11 and IL-11Rα were over-expressed in pulmonary arteries (3.2-fold and 75-fold respectively) and serum (1.5-fold and 2-fold respectively) of patients with iPAH. Therapeutic transient transfection with siRNA targeting IL-11 resulted in a significant reduction in pulmonary artery remodeling (by 98%), right heart hypertrophy (by 66%), and pulmonary hypertension (by 58%) in rats exposed to monocrotaline treatment. rhIL-11 and soluble rhIL-11Rα induce HPASMC proliferation and HPAEC to monocyte interactions, mesenchymal transition, and tube formation. Neutralizing monoclonal IL-11 and IL-11Rα antibodies inhibited TGFβ1 and EDN-1 induced HPAEC to mesenchymal transition and HPASMC proliferation. In 3D PCLS, rhIL-11 and soluble rhIL-11Rα do not promote pulmonary artery contraction but sensitize PCLS pulmonary artery contraction induced by EDN-1. In summary, IL-11 and IL-11Rα are more highly expressed in the pulmonary arteries of iPAH patients and contribute to pulmonary artery remodeling and the development of PH.

Superparamagnetic iron oxide nanoparticles target BxPC-3 cells and silence MUC4 for theranostics of pancreatic cancer

PURPOSE

Superparamagnetic iron oxide nanoparticles (SPION) are excellent magnetic resonance imaging (MRI) contrast agents. Mucin 4 (MUC4) acts as pancreatic cancer (PC) tumor antigen and influences PC progression. Small interfering RNAs (siRNAs) are used as a gene-silencing tool to treat a variety of diseases.

METHODS

We designed a therapeutic probe based on polyetherimide-superparamagnetic iron oxide nanoparticles (PEI-SPION) combined with siRNA nanoprobes (PEI-SPION-siRNA) to assess the contrast in MRI. The biocompatibility of the nanocomposite, and silencing of MUC4 were characterized and evaluated.

RESULTS

The prepared molecular probe had a particle size of 61.7 ± 18.5 nmand a surface of 46.7 ± 0.8mVand showed good biocompatibility in vitro and T2 relaxation efficiency. It can also load and protect siRNA. PEI-SPION-siRNA showed a good silencing effect on MUC4.

CONCLUSION

PEI-SPION-siRNA may be beneficial as a novel theranostic tool for PC.

Molecular Profiling of Tissue Samples with Chronic Rejection from Patients with Chronic Lung Allograft Dysfunction: A Pilot Study in Cystic Fibrosis Patients

Chronic rejection (CR) is the main culprit for reduced survival and quality of life in patients undergoing lung transplantation (Ltx). High-throughput approaches have been used to unveil the molecular pathways of CR, mainly in the blood and/or in bronchoalveolar lavage. We hypothesized that a distinct molecular signature characterizes the biopsies of recipients with clinically confirmed histological signs of CR. Eighteen cystic fibrosis patients were included in the study and RNA sequencing was performed in 35 scheduled transbronchial biopsies (TBBs): 5 with acute cellular rejection, 9 with CR, and 13 without any sign of post-LTx complication at the time of biopsy; 8 donor lung samples were used as controls. Three networks with 33, 26, and 36 differentially expressed genes (DEGs) were found in TBBs with CR. Among these, seven genes were common to the identified pathways and possibly linked to CR and five of them (LCN2, CCL11, CX3CL1, CXCL12, MUC4) were confirmed by real-time PCR. Immunohistochemistry was significant for LCN2 and MUC4. This study identified a typical gene expression pattern in TBBs with histological signs of CR and the LCN2 gene appeared to play a central role. Thus, it could be crucial in CR pathophysiology.

A2aR inhibits fibrosis and the EMT process in silicosis by regulating Wnt/β-catenin pathway

Silicosis, a disease characterized by diffuse fibrosis of the lung tissue, is caused by long-term inhalation of free silica (SiO2) dust in the occupational environment and is currently the most serious occupational diseases of pneumoconiosis. Several studies have suggested that alveolar type Ⅱ epithelial cells (AEC Ⅱ) undergo epithelial-mesenchymal transition (EMT) as one of the crucial components of silicosis in lung fibroblasts. A2aR can play a critical regulatory role in fibrosis-related diseases by modulating the Wnt/β-catenin pathway, but its function in the EMT process of silicosis has not been explained. In this study, an EMT model of A549 cells was established. The results revealed that A2aR expression is reduced in the EMT model. Furthermore, activation of A2aR or suppression of the Wnt/β-catenin pathway reversed the EMT process, while the opposite result was obtained by inhibiting A2aR. In addition, activation of A2aR in a mouse silicosis model inhibited the Wnt/β-catenin pathway and ameliorated the extent of silica-induced lung fibrosis in mice. To sum up, we uncovered that A2aR inhibits fibrosis and the EMT process in silicosis by regulating the Wnt/β-catenin pathway. Our study can provide an experimental basis for elucidating the role of A2aR in the development of silicosis and offer new ideas for further exploration of interventions for silicosis.

Bone morphogenetic protein 4 inhibits pulmonary fibrosis by modulating cellular senescence and mitophagy in lung fibroblasts

BACKGROUND

Accumulation of myofibroblasts is critical to fibrogenesis in idiopathic pulmonary fibrosis (IPF). Senescence and insufficient mitophagy in fibroblasts contribute to their differentiation into myofibroblasts, thereby promoting the development of lung fibrosis. Bone morphogenetic protein 4 (BMP4), a multifunctional growth factor, is essential for the early stage of lung development; however, the role of BMP4 in modulating lung fibrosis remains unknown.

METHODS

The aim of this study was to evaluate the role of BMP4 in lung fibrosis using BMP4-haplodeleted mice, BMP4-overexpressed mice, primary lung fibroblasts and lung samples from patients with IPF.

RESULTS

BMP4 expression was downregulated in IPF lungs and fibroblasts compared to control individuals, negatively correlated with fibrotic genes, and BMP4 decreased with transforming growth factor (TGF)-β1 stimulation in lung fibroblasts in a time- and dose-dependent manner. In mice challenged with bleomycin, BMP4 haploinsufficiency perpetuated activation of lung myofibroblasts and caused accelerated lung function decline, severe fibrosis and mortality. BMP4 overexpression using adeno-associated virus 9 vectors showed preventative and therapeutic efficacy against lung fibrosis. In vitro, BMP4 attenuated TGF-β1-induced fibroblast-to-myofibroblast differentiation and extracellular matrix (ECM) production by reducing impaired mitophagy and cellular senescence in lung fibroblasts. Pink1 silencing by short-hairpin RNA transfection abolished the ability of BMP4 to reverse the TGF-β1-induced myofibroblast differentiation and ECM production, indicating dependence on Pink1-mediated mitophagy. Moreover, the inhibitory effect of BMP4 on fibroblast activation and differentiation was accompanied with an activation of Smad1/5/9 signalling and suppression of TGF-β1-mediated Smad2/3 signalling in vivo and in vitro.

CONCLUSION

Strategies for enhancing BMP4 signalling may represent an effective treatment for pulmonary fibrosis.

IL-11 system participates in pulmonary artery remodeling and hypertension in pulmonary fibrosis

Background

Pulmonary hypertension (PH) associated to idiopathic pulmonary fibrosis (IPF) portends a poor prognosis. IL-11 has been implicated in fibrotic diseases, but their role on pulmonary vessels is unknown. Here we analyzed the contribution of IL-11 to PH in patients with IPF and the potential mechanism implicated.

Methods

Pulmonary arteries, lung tissue and serum of control subjects (n = 20), IPF (n = 20) and PH associated to IPF (n = 20) were used to study the expression and localization of IL-11 and IL-11Rα. Two models of IL-11 and bleomycin-induced lung fibrosis associated to PH were used in Tie2-GFP transgenic mice to evaluate the contribution of IL-11 and endothelial cells to pulmonary artery remodeling. The effect of IL-11 and soluble IL-11Rα on human pulmonary artery endothelial cells and smooth muscle cell transformations and proliferation were analyzed.

Results

IL-11 and IL-11Rα were over-expressed in pulmonary arteries and serum of patients with PH associated to IPF vs IPF patients without PH. Recombinant mice (rm)IL-11 induced lung fibrosis and PH in Tie2-GFP mice, activating in vivo EnMT as a contributor of pulmonary artery remodeling and lung fibrosis. Transient transfection of siRNA-IL-11 reduced lung fibrosis and PH in Tie2-GFP bleomycin model. Human (h)rIL-11 and soluble hrIL-11Rα induced endothelial to mesenchymal transition (EnMT) and pulmonary artery smooth muscle cell to myofibroblast-like transformation, cell proliferation and senescence in vitro.

Conclusions

IL-11 and IL-11Rα are overexpressed in pulmonary arteries of PH associated to IPF patients, and contributes to pulmonary artery remodeling and PH.

Mammalian Neuraminidases in Immune-Mediated Diseases: Mucins and Beyond

Mammalian neuraminidases (NEUs), also known as sialidases, are enzymes that cleave off the terminal neuraminic, or sialic, acid resides from the carbohydrate moieties of glycolipids and glycoproteins. A rapidly growing body of literature indicates that in addition to their metabolic functions, NEUs also regulate the activity of their glycoprotein targets. The simple post-translational modification of NEU protein targets-removal of the highly electronegative sialic acid-affects protein folding, alters protein interactions with their ligands, and exposes or covers proteolytic sites. Through such effects, NEUs regulate the downstream processes in which their glycoprotein targets participate. A major target of desialylation by NEUs are mucins (MUCs), and such post-translational modification contributes to regulation of disease processes. In this review, we focus on the regulatory roles of NEU-modified MUCs as coordinators of disease pathogenesis in fibrotic, inflammatory, infectious, and autoimmune diseases. Special attention is placed on the most abundant and best studied NEU1, and its recently discovered important target, mucin-1 (MUC1). The role of the NEU1 - MUC1 axis in disease pathogenesis is discussed, along with regulatory contributions from other MUCs and other pathophysiologically important NEU targets.

Simultaneous solubilization and extended release of insoluble drug as payload in highly soluble particles of γ-cyclodextrin metal-organic frameworks

The inclusion and nanocluster formed in cyclodextrin-metal organic framework (CD-MOF) make it a remarkable vehicle in improving the solubility and bioavailability of insoluble drugs, but rarely in elongation of drug release kinetics. In this research, an insoluble compound, 18β-glycyrrhetinic acid (GA), encapsulated in CD-MOF (GA@nano-CD-MOF) had prominent effects in the treatment of bleomycin-induced idiopathic pulmonary fibrosis in rats with an enhanced bioavailability by 6.8 times. The solubility of GA@nano-CD-MOF was 7780 times higher than that of GA, which was explained by the solubility parameter of amorphous cells constructed in silico simulation. CD-MOF imparted GA unique biphasic release kinetics, namely, GA released instantly to 52% and slowly released to 100% for a period of 5 days, which made the drug loaded particles much more flexible in pharmaceutical applications. The distribution of GA molecules in CD-MOF and drug loading priority obtained by molecular docking illustrated the formation of biphasic release mode at the molecular level combined with other characterizations of SEM, PXRD, TGA and DSC. In conclusion, CD-MOF has a unique effect to simultaneously solubilize an insoluble drug and extend its release for days as payload in highly soluble particles of γ-cyclodextrin metal-organic frameworks, which broaden the applications of drugs in specific treatment and then enhance the therapeutic effects.

Recurring exposure to low humidity induces transcriptional and protein level changes in the vocal folds of rabbits

Voice disorders are an important human health condition. Hydration is a commonly recommended preventive measure for voice disorders though it is unclear how vocal fold dehydration is harmful at the cellular level. Airway surface dehydration can result from exposure to low humidity air. Here we have induced airway surface dehydration in New Zealand White rabbits exposed to a recurring 8-h low humidity environment over 15 days. This model mimics an occupational exposure to a low humidity environment. Exposure to moderate humidity was the control condition. Full thickness soft-tissue samples, including the vocal folds and surrounding laryngeal tissue, were collected for molecular analysis. RT-qPCR demonstrated a significant upregulation of MUC4 (mucin 4) and SCL26A9 (chloride channel) and a large fold-change though statistically non-significant upregulation of SCNNA1 (epithelial sodium channel). Proteomic analysis demonstrated differential regulation of proteins clustering into prospective functional groups of muscle structure and function, oxidative stress response, and protein chaperonin stress response. Together, the data demonstrate that recurring exposure to low humidity is sufficient to induce both transcriptional and translational level changes in laryngeal tissue and suggest that low humidity exposure induces cellular stress at the level of the vocal folds.

PM2.5 and water-soluble components induce airway fibrosis through TGF-β1/Smad3 signaling pathway in asthmatic rats

Epidemiological studies have suggested that fine particulate matter (PM_2.5) and asthma have been independently associated with pulmonary fibrosis but rarely studied together. Furthermore, it is unknown whether airway fibrosis in asthma is more attributable to water-soluble ions of PM_2.5. Our current study was to explore the potential mechanism of PM_2.5 and water-soluble components on airway fibrosis in ovalbumin (OVA)-sensitized asthmatic rats. Rats were intratracheally instilled with PM_2.5 and water-soluble components every 3 days for 4 times or 8 times. Histopathological examination demonstrated that lung inflammatory and airway fibrosis were induced after PM_2.5 and water-soluble components exposure. Meanwhile, PM_2.5, in particular water-soluble extracts, increased expression of collagen 1 (COL-1), connective tissue growth factor (CTGF), interleukin-6 (IL-6), transforming growth factor-β1 (TGF-β1), Smad family member 3 (Smad3), and p-Smad3, whereas decreased secretion of heme oxygenase-1 (HO-1). However, pretreating asthmatic rats with SB432542, the inhibitor of TGF-β1, and SIS3 HCl, the antagonist of Smad3, both reversed the activation of airway fibrosis induced by water-soluble extracts. Therefore, TGF-β1/Smad3 signaling pathway may be responsible for the pathological process of airway fibrosis in asthmatic rats following PM_2.5 and water-soluble components exposure.

MUC16 Is Overexpressed in Idiopathic Pulmonary Fibrosis and Induces Fibrotic Responses Mediated by Transforming Growth Factor-β1 Canonical Pathway

Several transmembrane mucins have demonstrated that they contribute intracellularly to induce fibrotic processes. The extracellular domain of MUC16 is considered as a biomarker for disease progression and death in IPF patients. However, there is no evidence regarding the signalling capabilities of MUC16 that contribute to IPF development. Here, we demonstrate that MUC16 was overexpressed in the lung tissue of IPF patients (n = 20) compared with healthy subjects (n = 17) and localised in fibroblasts and hyperplastic alveolar type II cells. Repression of MUC16 expression by siRNA-MUC16 transfection inhibited the TGF-β1-induced fibrotic processes such as mesenchymal/ myofibroblast transformations of alveolar type II A549 cells and lung fibroblasts, as well as fibroblast proliferation. SiRNA-MUC16 transfection also decreased the TGF-β1-induced SMAD3 phosphorylation, thus inhibiting the Smad Binding Element activation. Immunoprecipitation assays and confocal immunofluorescence showed the formation of a protein complex between MUC16/p-SMAD3 in the cell membrane after TGF-β1 stimulation. This study shows that MUC16 is overexpressed in IPF and collaborates with the TGF-β1 canonical pathway to induce fibrotic processes. Therefore, direct or indirect targeting of MUC16 could be a potential drug target for human IPF.

The Epithelial-Immune Crosstalk in Pulmonary Fibrosis

Interactions between the lung epithelium and the immune system involve a tight regulation to prevent inappropriate reactions and have been connected to several pulmonary diseases. Although the distal lung epithelium and local immunity have been implicated in the pathogenesis and disease course of idiopathic pulmonary fibrosis (IPF), consequences of their abnormal interplay remain less well known. Recent data suggests a two-way process, as illustrated by the influence of epithelial-derived periplakin on the immune landscape or the effect of macrophage-derived IL-17B on epithelial cells. Additionally, damage associated molecular patterns (DAMPs), released by damaged or dying (epithelial) cells, are augmented in IPF. Next to “sterile inflammation”, pathogen-associated molecular patterns (PAMPs) are increased in IPF and have been linked with lung fibrosis, while outer membrane vesicles from bacteria are able to influence epithelial-macrophage crosstalk. Finally, the advent of high-throughput technologies such as microbiome-sequencing has allowed for the identification of a disease-specific microbial environment. In this review, we propose to discuss how the interplays between the altered distal airway and alveolar epithelium, the lung microbiome and immune cells may shape a pro-fibrotic environment. More specifically, it will highlight DAMPs-PAMPs pathways and the specificities of the IPF lung microbiome while discussing recent elements suggesting abnormal mucosal immunity in pulmonary fibrosis.