Circulating matrix metalloproteinases and tissue metalloproteinase inhibitors in patients with idiopathic pulmonary fibrosis in the multicenter IPF-PRO Registry cohort

Geneticin ameliorates pulmonary fibrosis by attenuating the TGF-β/Smad via modulating AMPK/SIRT1 signaling

AIM

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive condition with unknown aetiology that causes the lung parenchyma to scar incessantly, lowering the quality of life and hastening death. In this investigation, we studied the anti-fibrotic activity of Geneticin (a derivative of gentamycin) using in vitro and in vivo models.

MAIN METHODS

The TGF-β-mediated differentiation model was adopted to investigate (fibrotic marker's levels/expression) the anti-fibrotic activity of geneticin (GNC) in in-vitro scenarios (LL29 and DHLF cells). In vivo, the bleomycin (BLM)-induced pulmonary fibrosis model was employed by administering BLM intratracheally. Post 14 days of BLM administration, animals were treated with geneticin (6.25, 12.5, and 25 mg·kg-1) for another 14 days, and their therapeutic effect was investigated using a spectrum of techniques.

KEY FINDINGS

RTqPCR and western-blot results revealed that geneticin treatment significantly attenuated the TGF-β/BLM mediated fibrotic cascade of markers in both in-vitro and in-vivo models respectively. Further, the BLM-induced pulmonary fibrosis model revealed, that geneticin dose-dependently reduced the BLM-induced inflammatory cell infiltrations, and thickness of the alveoli walls, improved the structural distortion of the lung, and aided in improving the survival rate of the rats. Picrosirus and Masson's trichrome staining indicated that geneticin therapy reduced collagen deposition and, as a result, lung functional characteristics were improved as assessed by flexivent. Mechanistic studies have shown that geneticin reduced fibrosis by attenuating the TGF-β/Smad through modulating the AMPK/SIRT1 signaling.

SIGNIFICANCE

These findings suggest that geneticin may be a promising therapeutic agent for the treatment of pulmonary fibrosis in clinical settings.

Proteomic Biomarkers of Quantitative Interstitial Abnormalities in COPDGene and CARDIA Lung Study

Rationale: Quantitative interstitial abnormalities (QIAs) are early measures of lung injury automatically detected on chest computed tomography scans. QIAs are associated with impaired respiratory health and share features with advanced lung diseases, but their biological underpinnings are not well understood. Objectives: To identify novel protein biomarkers of QIAs using high-throughput plasma proteomic panels within two multicenter cohorts. Methods: We measured the plasma proteomics of 4,383 participants in an older, ever-smoker cohort (COPDGene [Genetic Epidemiology of Chronic Obstructive Pulmonary Disease]) and 2,925 participants in a younger population cohort (CARDIA [Coronary Artery Disease Risk in Young Adults]) using the SomaLogic SomaScan assays. We measured QIAs using a local density histogram method. We assessed the associations between proteomic biomarker concentrations and QIAs using multivariable linear regression models adjusted for age, sex, body mass index, smoking status, and study center (Benjamini-Hochberg false discovery rate-corrected P ⩽ 0.05). Measurements and Main Results: In total, 852 proteins were significantly associated with QIAs in COPDGene and 185 in CARDIA. Of the 144 proteins that overlapped between COPDGene and CARDIA, all but one shared directionalities and magnitudes. These proteins were enriched for 49 Gene Ontology pathways, including biological processes in inflammatory response, cell adhesion, immune response, ERK1/2 regulation, and signaling; cellular components in extracellular regions; and molecular functions including calcium ion and heparin binding. Conclusions: We identified the proteomic biomarkers of QIAs in an older, smoking population with a higher prevalence of pulmonary disease and in a younger, healthier community cohort. These proteomics features may be markers of early precursors of advanced lung diseases.

Lactate transport inhibition therapeutically reprograms fibroblast metabolism in experimental pulmonary fibrosis

Myofibroblast differentiation, essential for driving extracellular matrix synthesis in pulmonary fibrosis, requires increased glycolysis. While glycolytic cells must export lactate, the contributions of lactate transporters to myofibroblast differentiation are unknown. In this study, we investigated how MCT1 and MCT4, key lactate transporters, influence myofibroblast differentiation and experimental pulmonary fibrosis. Our findings reveal that inhibiting MCT1 or MCT4 reduces TGFβ-stimulated pulmonary myofibroblast differentiation in vitro and decreases bleomycin-induced pulmonary fibrosis in vivo. Through comprehensive metabolic analyses, including bioenergetics, stable isotope tracing, metabolomics, and imaging mass spectrometry in both cells and mice, we demonstrate that inhibiting lactate transport enhances oxidative phosphorylation, reduces reactive oxygen species production, and diminishes glucose metabolite incorporation into fibrotic lung regions. Furthermore, we introduce VB253, a novel MCT4 inhibitor, which ameliorates pulmonary fibrosis in both young and aged mice, with comparable efficacy to established antifibrotic therapies. These results underscore the necessity of lactate transport for myofibroblast differentiation, identify MCT1 and MCT4 as promising pharmacologic targets in pulmonary fibrosis, and support further evaluation of lactate transport inhibitors for patients for whom limited therapeutic options currently exist.

Identification and validation of mutual hub genes in idiopathic pulmonary fibrosis and rheumatoid arthritis-associated usual interstitial pneumonia

Objectives

The study aims at exploring common hub genes and pathways in idiopathic pulmonary fibrosis (IPF) and rheumatoid arthritis-associated usual interstitial pneumonia (RA-UIP) through integrated bioinformatics analyses.

Methods

The GSE199152 dataset containing lung tissue samples from IPF and RA-UIP patients was acquired from the Gene Expression Omnibus (GEO) database. The identification of overlapping differentially expressed genes (DEGs) in IPF and RA-UIP was carried out through R language. Protein-protein interaction (PPI) network analysis and module analysis were applied to filter mutual hub genes in the two diseases. Enrichment analyses were also conducted to analyze the possible biological functions and pathways of the overlapped DEGs and hub genes. The diagnostic value of key genes was assessed with R language, and the expressions of these genes in pulmonary cells of IPF and rheumatoid arthritis-associated interstitial lung disease (RA-ILD) patients were analyzed with single cell RNA-sequencing (scRNA-seq) datasets. The expression levels of hub genes were validated in blood samples from patients, specimens of human lung fibroblasts, lung tissue samples from mice, as well as external GEO datasets.

Results

Four common hub genes (THBS2, TIMP1, POSTN, and CD19) were screened. Enrichment analyses showed that the abnormal expressions of DEGs and hub genes may be connected with the onset of IPF and RA-UIP by regulating the progression of fibrosis. ScRNA-seq analyses illustrated that for both IPF and RA-ILD patients, THBS2, TIMP1, and POSTN were mainly expressed in lung fibroblasts, while CD19 was uniquely high-expressed in B cells. The qRT-PCR and immunohistochemistry (IHC) results verified that the expression levels of hub genes were mostly in accordance with the findings obtained from the bioinformatics analyses.

Conclusion

Though IPF and RA-UIP are distinct diseases, they may to some extent have mutual pathogenesis in the development of fibrosis. THBS2, TIMP1, POSTN, and CD19 may be the potential biomarkers of IPF and RA-UIP, and intervention on related pathways of these genes could offer new strategies for the precision treatment of IPF and RA-UIP.

Pulmonary Fibrosis and Diabetes Mellitus: Two coins with the same face

Idiopathic pulmonary fibrosis (IPF) constitutes a long-term disease with a complex pathophysiology composed of multiple molecular actors that lead to the deposition of extracellular matrix, the loss of pulmonary function and ultimately the patient's death. Despite the approval of pirfenidone and nintedanib for the treatment of the disease, lung transplant is the only long-term solution to fully recover the respiratory capacity and gain quality of life. One of the risk factors for the development of IPF is the pre-existing condition of diabetes mellitus. Both, IPF and diabetes mellitus, share similar pathological damage mechanisms, including inflammation, endoplasmic reticulum stress, mitochondrial failure, oxidative stress, senescence and signaling from glycated proteins through receptors. In this critical review article, we provide information about this interrelationship, examining molecular mediators that play an essential role in both diseases and identify targets of interest for the development of potential drugs. We review the findings of clinical trials examining the progression of IPF and how novel molecules may be used to stop this process. The results highlight the importance of early detection and addressing multiple therapeutic targets simultaneously to achieve better therapeutic efficacy and potentially reverse lung fibrosis.

The role of matrix metalloproteinase 9 in fibrosis diseases and its molecular mechanisms

Fibrosis is a process of tissue repair that results in the slow creation of scar tissue to replace healthy tissue and can affect any tissue or organ. Its primary feature is the massive deposition of extracellular matrix (mainly collagen), eventually leading to tissue dysfunction and organ failure. The progression of fibrotic diseases has put a significant strain on global health and the economy, and as a result, there is an urgent need to find some new therapies. Previous studies have identified that inflammation, oxidative stress, some cytokines, and remodeling play a crucial role in fibrotic diseases and are essential avenues for treating fibrotic diseases. Among them, matrix metalloproteinases (MMPs) are considered the main targets for the treatment of fibrotic diseases since they are the primary driver involved in ECM degradation, and tissue inhibitors of metalloproteinases (TIMPs) are natural endogenous inhibitors of MMPs. Through previous studies, we found that MMP-9 is an essential target for treating fibrotic diseases. However, it is worth noting that MMP-9 plays a bidirectional regulatory role in different fibrotic diseases or different stages of the same fibrotic disease. Previously identified MMP-9 inhibitors, such as pirfenidone and nintedanib, suffer from some rather pronounced side effects, and therefore, there is an urgent need to investigate new drugs. In this review, we explore the mechanism of action and signaling pathways of MMP-9 in different tissues and organs, hoping to provide some ideas for developing safer and more effective biologics.

Predictive biomarkers of disease progression in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic interstitial disease that cannot be cured, and treatment options for IPF are very limited. Early diagnosis, close monitoring of disease progression, and timely treatment are therefore the best options for patients due to the irreversibility of IPF. Effective markers help doctors judge the development and prognosis of disease. Recent research on traditional biomarkers (KL-6, SP-D, MMP-7, TIMPs, CCL18) has provided novel ideas for predicting disease progression and prognosis. Some emerging biomarkers (HE4, GDF15, PRDX4, inflammatory cells, G-CSF) also provide more possibilities for disease prediction. In addition to markers in serum and bronchoalveolar lavage fluid (BALF), some improvements related to the GAP model and chest HRCT also show good predictive ability for disease prognosis.

Olfactory mucosa mesenchymal stem cells alleviate pulmonary fibrosis via the immunomodulation and reduction of inflammation

BACKGROUND

Pulmonary fibrosis (PF) is a progressive fibrosing interstitial pneumonia that leads to respiratory failure and other complications, which is ultimately fatal. Mesenchymal stem cells (MSCs) transplant is a promising strategy to solve this problem, while the procurement of MSCs from the patient for autotransplant remains a challenge.

METHODS

Here, we presented olfactory mucosa mesenchymal stem cells (OM-MSCs) from mouse turbinate and determined the preventing efficacy of allotransplant for PF. We demonstrated the antiinflammation and immunomodulatory effects of OM-MSCs. Flow cytometric analysis was used to verify the effect of OM-MSCs on monocyte-derived macrophage populations in the lung.

RESULTS

Administration of OM-MSCs reduces inflammation, attenuates the matrix metallopeptidase 13 (MMP13) expression level and restores the bleomycin (BLM)-induced pulmonary fibrosis by assessing the architecture of lung, collagen type I; (COL1A1), actin alpha 2, smooth muscle, aorta (ACTA2/α-SMA) and hydroxyproline. This therapeutic effect of OM-MSCs was related to the increase in the ratio of nonclassical monocytes to proinflammatory monocytes in the lung.

CONCLUSIONS

This study suggests that transplant of OM-MSCs represents an effective and safe treatment for PF.

Macrophage-derived MMP12 promotes fibrosis through sustained damage to endothelial cells

Macrophages are essential for the maintenance of endothelial cell function. However, the potential impact and mechanisms of crosstalk between macrophages and endothelial cells during silicosis progression remain unexplored. To fill this knowledge gap, a mouse model of silicosis was established. Single cell sequencing, spatial transcriptome sequencing, western blotting, immunofluorescence staining, tube-forming and wound healing assays were used to explore the effects of silicon dioxide on macrophage-endothelial interactions. To investigate the mechanism of macrophage-mediated fibrosis, MMP12 was specifically inactivated using siRNA and pharmacological approaches, and macrophages were depleted using disodium chlorophosphite liposomes. Compared to the normal saline group, the silica dust group showed altered macrophage-endothelial interactions. Matrix metalloproteinase family member MMP12 was identified as a key mediator of the altered function of macrophage-endothelial interactions after silica exposure, which was accompanied by pro-inflammatory macrophage activation and fibrotic progression. By using ablation strategies, macrophage-derived MMP12 was shown to mediate endothelial cell dysfunction by accumulating on the extracellular matrix. During the inflammatory phase of silicosis, MMP12 secreted by pro-inflammatory macrophages caused decreased endothelial cell viability, reduced migration, decreased trans-endothelial resistance and increased permeability; while during the fibrotic phase, macrophage-derived MMP12 sustained endothelial cell injury through accumulation on the extracellular matrix.

Nanotechnology Applications in Breast Cancer Immunotherapy

Next-generation cancer treatments are expected not only to target cancer cells but also to simultaneously train immune cells to combat cancer while modulating the immune-suppressive environment of tumors and hosts to ensure a robust and lasting response. Achieving this requires carriers that can codeliver multiple therapeutics to the right cancer and/or immune cells while ensuring patient safety. Nanotechnology holds great potential for addressing these challenges. This article highlights the recent advances in nanoimmunotherapeutic development, with a focus on breast cancer. While immune checkpoint inhibitors (ICIs) have achieved remarkable success and lead to cures in some cancers, their response rate in breast cancer is low. The poor response rate in solid tumors is often associated with the low infiltration of anti-cancer T cells and an immunosuppressive tumor microenvironment (TME). To enhance anti-cancer T-cell responses, nanoparticles are employed to deliver ICIs, bispecific antibodies, cytokines, and agents that induce immunogenic cancer cell death (ICD). Additionally, nanoparticles are used to manipulate various components of the TME, such as immunosuppressive myeloid cells, macrophages, dendritic cells, and fibroblasts to improve T-cell activities. Finally, this article discusses the outlook, challenges, and future directions of nanoimmunotherapeutics.

Catch your breath: The protective role of the angiotensin AT2 receptor for the treatment of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease whereby excessive deposition of extracellular matrix proteins (ECM) ultimately leads to respiratory failure. While there have been advances in pharmacotherapies for pulmonary fibrosis, IPF remains an incurable and irreversible disease. There remains an unmet clinical need for treatments that reverse fibrosis, or at the very least have a more tolerable side effect profile than currently available treatments. Transforming growth factor β1(TGFβ1) is considered the main driver of fibrosis in IPF. However, as our understanding of the role of the pulmonary renin-angiotensin system (PRAS) in the pathogenesis of IPF increases, it is becoming clear that targeting angiotensin receptors represents a potential novel treatment strategy for IPF - in particular, via activation of the anti-fibrotic angiotensin type 2 receptor (AT2R). This review describes the current understanding of the pathophysiology of IPF and the mediators implicated in its pathogenesis; focusing on TGFβ1, angiotensin II and related peptides in the PRAS and their contribution to fibrotic processes in the lung. Preclinical and clinical assessment of currently available AT2R agonists and the development of novel, highly selective ligands for this receptor will also be described, with a focus on compound 21, currently in clinical trials for IPF. Collectively, this review provides evidence of the potential of AT2R as a novel therapeutic target for IPF.

The Anti-atherosclerosis Mechanism of Ziziphora clinopodioides Lam. Based On Network Pharmacology

We investigated the mechanisms underlying the effects of Ziziphora clinopodioides Lam. (ZCL) on atherosclerosis (AS) using network pharmacology and in vitro validation.We collected the active components of ZCL and predicted their targets in AS. We constructed the protein-protein interaction, compound-target, and target-compound-pathway networks, and performed GO and KEGG analyses. Molecular docking of the active components and key targets was constructed with Autodock and Pymol software. Validation was performed with qRT-PCR, ELISA, and Western blot.We obtained 80 components of ZCL. The network analysis identified that 14 components and 37 genes were involved in AS. Then, 10 key nodes in the PPI network were identified as the key targets of ZCL because of their importance in network topology. The binding energy of 8 components (Cynaroside, α-Spinasterol, Linarin, Kaempferide, Acacetin, Genkwanin, Chrysin, and Apiin) to 4 targets (MMP9, TP53, AKT1, SRC) was strong and <-1 kJ/mol. In addition, 13 of the 14 components were flavonoids and thus total flavonoids of Ziziphora clinopodioides Lam. (ZCF) were used for in vitro validation. We found that ZCF reduced eNOS, P22phox, gp91phox, and PCSK9 at mRNA and protein levels, as well as the levels of IL-1β, TNF-α, and IL-6 proteins in vitro (P < 0.05).We successfully predicted the active components, targets, and mechanisms of ZCL in treating AS using network pharmacology. We confirmed that ZCF may play a role in AS by modulating oxidative stress, lipid metabolism, and inflammatory response via Cynaroside, Linarin, Kaempferide, Acacetin, Genkwanin, Chrysin, and Apiin.

Progress in understanding and treating idiopathic pulmonary fibrosis: recent insights and emerging therapies

Idiopathic pulmonary fibrosis (IPF) is a long-lasting, continuously advancing, and irrevocable interstitial lung disorder with an obscure origin and inadequately comprehended pathological mechanisms. Despite the intricate and uncharted causes and pathways of IPF, the scholarly consensus upholds that the transformation of fibroblasts into myofibroblasts-instigated by injury to the alveolar epithelial cells-and the disproportionate accumulation of extracellular matrix (ECM) components, such as collagen, are integral to IPF's progression. The introduction of two novel anti-fibrotic medications, pirfenidone and nintedanib, have exhibited efficacy in decelerating the ongoing degradation of lung function, lessening hospitalization risk, and postponing exacerbations among IPF patients. Nonetheless, these pharmacological interventions do not present a definitive solution to IPF, positioning lung transplantation as the solitary potential curative measure in contemporary medical practice. A host of innovative therapeutic strategies are presently under rigorous scrutiny. This comprehensive review encapsulates the recent advancements in IPF research, spanning from diagnosis and etiology to pathological mechanisms, and introduces a discussion on nascent therapeutic methodologies currently in the pipeline.

The endothelium in lung fibrosis: a core signaling hub in disease pathogenesis?

Pulmonary fibrosis (PF) is a progressive chronic lung disease characterized by excessive deposition of extracellular matrix (ECM) and structural destruction, associated with a severe 5-year mortality rate. The onset of the disease is thought to be triggered by chronic damage to the alveolar epithelium. Since the pulmonary endothelium is an important component of the alveolar-capillary niche, it is also affected by the initial injury. In addition to ensuring proper gas exchange, the endothelium has critical functional properties, including regulation of vascular tone, inflammatory responses, coagulation, and maintenance of vascular homeostasis and integrity. Recent single-cell analyses have shown that shifts in endothelial cell (EC) subtypes occur in PF. Furthermore, the increased vascular remodeling associated with PF leads to deteriorated outcomes for patients, underscoring the importance of the vascular bed in PF. To date, the causes and consequences of endothelial and vascular involvement in lung fibrosis are poorly understood. Therefore, it is of great importance to investigate the involvement of EC and the vascular system in the pathogenesis of the disease. In this review, we will outline the current knowledge on the role of the pulmonary vasculature in PF, in terms of abnormal cellular interactions, hyperinflammation, vascular barrier disorders, and an altered basement membrane composition. Finally, we will summarize recent advances in extensive therapeutic research and discuss the significant value of novel therapies targeting the endothelium.

A serologically assessed neo-epitope biomarker of cellular fibronectin degradation is related to pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is characterized by excessive extracellular matrix (ECM) remodeling, herein ECM degradation. Fibronectin (FN) is an important component of the ECM that is produced by multiple cell types, including fibroblasts. Extra domain B (EDB) is specific for a cellular FN isoform which is found in the ECM. We sought to develop a non-invasive test to investigate whether matrix metalloproteinase 8 (MMP-8) degradation of EDB in cellular FN results in a specific protein fragment that can be assessed serologically and if levels relate to pulmonary fibrosis.

METHOD

Cellular FN was cleaved in vitro by MMP-8 and a protein fragment was identified by mass spectrometry. A monoclonal antibody (mAb) was generated, targeting a neo-epitope originating from EDB in cellular FN. Utilizing this mAb, a neo-epitope specific enzyme-linked immunosorbent assay (FN-EDB) was developed and technically validated. Serum FN-EDB was assessed in an IPF cohort (n=98), registered at clinicaltrials.gov (NCT02818712), and in healthy controls (n=35).

RESULTS

The FN-EDB assay had high specificity for the MMP-8 degraded neo-epitope and was technically robust. FN-EDB serum levels were not influenced by age, sex, ethnicity, or BMI. Moreover, FN-EDB serum levels were significantly higher in IPF patients (median 31.38 [IQR 25.79-46.84] ng/mL) as compared to healthy controls (median 28.05 [IQR 21.58-33.88] ng/mL, p=0.023).

CONCLUSION

We developed the neo-epitope specific FN-EDB assay, a competitive ELISA, as a tool for serological assessment of MMP-8 mediated degradation of EDB in cellular FN. This study indicates that degradation of EDB in cellular FN is elevated in IPF and warrants further investigation.

Dysregulation of metabolic pathways in pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive disorder of unknown origin and the most common interstitial lung disease. It progresses with the recruitment of fibroblasts and myofibroblasts that contribute to the accumulation of extracellular matrix (ECM) proteins, leading to the loss of compliance and alveolar integrity, compromising the gas exchange capacity of the lung. Moreover, while there are therapeutics available, they do not offer a cure. Thus, there is a pressing need to identify better therapeutic targets. With the advent of transcriptomics, proteomics, and metabolomics, the cellular mechanisms underlying disease progression are better understood. Metabolic homeostasis is one such factor and its dysregulation has been shown to impact the outcome of IPF. Several metabolic pathways involved in the metabolism of lipids, protein and carbohydrates have been implicated in IPF. While metabolites are crucial for the generation of energy, it is now appreciated that metabolites have several non-metabolic roles in regulating cellular processes such as proliferation, signaling, and death among several other functions. Through this review, we succinctly elucidate the role of several metabolic pathways in IPF. Moreover, we also discuss potential therapeutics which target metabolism or metabolic pathways.

Biomarkers of cellular senescence in idiopathic pulmonary fibrosis

BACKGROUND

Cellular senescence is a cell fate in response to diverse forms of age-related damage and stress that has been implicated in the pathogenesis of idiopathic pulmonary fibrosis (IPF). The associations between circulating levels of candidate senescence biomarkers and disease outcomes have not been specifically studied in IPF. In this study we assessed the circulating levels of candidate senescence biomarkers in individuals affected by IPF and controls and evaluated their ability to predict disease outcomes.

METHODS

We measured the plasma concentrations of 32 proteins associated with senescence in Lung Tissue Research Consortium participants and studied their relationship with the diagnosis of IPF, parameters of pulmonary and physical function, health-related quality of life, mortality, and lung tissue expression of P16, a prototypical marker of cellular senescence. A machine learning approach was used to evaluate the ability of combinatorial biomarker signatures to predict disease outcomes.

RESULTS

The circulating levels of several senescence biomarkers were significantly elevated in persons affected by IPF compared to controls. A subset of biomarkers accurately classified participants as having or not having the disease and was significantly correlated with measures of pulmonary function, health-related quality of life and, to an extent, physical function. An exploratory analysis revealed senescence biomarkers were also associated with mortality in IPF participants. Finally, the plasma concentrations of several biomarkers were associated with their expression levels in lung tissue as well as the expression of P16.

CONCLUSIONS

Our results suggest that circulating levels of candidate senescence biomarkers are informative of disease status, pulmonary and physical function, and health-related quality of life. Additional studies are needed to validate the combinatorial biomarkers signatures that emerged using a machine learning approach.

Amelioration of Pulmonary Fibrosis by Matrix Metalloproteinase-2 Overexpression

Idiopathic pulmonary fibrosis is a progressive and fatal disease with a poor prognosis. Matrix metalloproteinase-2 is involved in the pathogenesis of organ fibrosis. The role of matrix metalloproteinase-2 in lung fibrosis is unclear. This study evaluated whether overexpression of matrix metalloproteinase-2 affects the development of pulmonary fibrosis. Lung fibrosis was induced by bleomycin in wild-type mice and transgenic mice overexpressing human matrix metalloproteinase-2. Mice expressing human matrix metalloproteinase-2 showed significantly decreased infiltration of inflammatory cells and inflammatory and fibrotic cytokines in the lungs compared to wild-type mice after induction of lung injury and fibrosis with bleomycin. The computed tomography score, Ashcroft score of fibrosis, and lung collagen deposition were significantly reduced in human matrix metalloproteinase transgenic mice compared to wild-type mice. The expression of anti-apoptotic genes was significantly increased, while caspase-3 activity was significantly reduced in the lungs of matrix metalloproteinase-2 transgenic mice compared to wild-type mice. Active matrix metalloproteinase-2 significantly decreased bleomycin-induced apoptosis in alveolar epithelial cells. Matrix metalloproteinase-2 appears to protect against pulmonary fibrosis by inhibiting apoptosis of lung epithelial cells.

Chronic Expression of a Clinical SFTPC Mutation Causes Murine Lung Fibrosis with Idiopathic Pulmonary Fibrosis Features

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive fibrotic interstitial lung disease. A barrier to developing more effective therapies for IPF is the dearth of preclinical models that recapitulate the early pathobiology of this disease. Intratracheal bleomycin, the conventional preclinical murine model of IPF, fails to reproduce the intrinsic dysfunction to the alveolar epithelial type 2 cell (AEC2) that is believed to be a proximal event in the pathogenesis of IPF. Murine fibrosis models based on SFTPC (Surfactant Protein C gene) mutations identified in patients with interstitial lung disease cause activation of the AEC2 unfolded protein response and endoplasmic reticulum stress-an AEC2 dysfunction phenotype observed in IPF. Although these models achieve spontaneous fibrosis, they do so with precedent lung injury and thus are challenged to phenocopy the general clinical course of patients with IPF-gradual progressive fibrosis and loss of lung function. Here, we report a refinement of a murine Sftpc mutation model to recapitulate the clinical course, physiological impairment, parenchymal cellular composition, and biomarkers associated with IPF. This platform provides the field with an innovative model to understand IPF pathogenesis and index preclinical therapeutic candidates.

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.

Lymphangioleiomyomatosis: Searching for potential biomarkers

Background

Vascular endothelial growth factor-D (VEGF-D) is the most commonly used biomarker for diagnosing lymphangioleiomyomatosis (LAM). However, lung biopsy is often necessary as well; therefore, defining new biomarkers for LAM is crucial. The aim of this study was to describe the diagnostic accuracy of a variety of biomarkers.

Methods

We assessed 13 analytes in serum related to extracellular matrix remodeling, lymphatic involvement and angiogenesis in a cohort of patients with LAM, comparing them with patients with other cystic lung diseases (OCLD) and healthy women. A scoring method based on the cut-point of each VEGF-D and metalloproteinase-2 (MMP-2) was used to evaluate the diagnostic performance of the marker combination.

Results

A total of 97 subjects were recruited: 59 (61%) LAM patients, 18 (19%) OCLD patients, and 20 (20%) healthy female controls. MMP-2 was the only extracellular matrix remodeling biomarker able to differentiate LAM patients from OCLD and healthy patients. Serum MMP-2 was higher in LAM patients [median 578 (465-832) ng/ml] than in patients with OCLD and healthy controls [medians 360 (314-546) and 427 (365-513) ng/ml, respectively (p < 0.0001)]. The area under ROC curve (AUC) of MMP-2 was 0.785 and that of VEGF-D 0.815 (p = 0.6214). The sensitivity/specificity profiles of each biomarker (54/92% for MMP-2, 59/95% for VEGF-D) yielded a composite score (-6.36 + 0.0059 × VEGF-D + 0.0069 × MMP-2) with higher accuracy than each component alone (AUC 0.88 and sensitivity/specificity 79/87%).

Conclusion

Combining MMP-2 and VEGF-D may increase diagnostic accuracy for LAM.

The Biology and Function of Tissue Inhibitor of Metalloproteinase 2 in the Lungs

Tissue inhibitors of matrix metalloproteinases (TIMP) are a family of four endogenous proteins that primarily function to inhibit the activities of proteases such as the matrix metalloproteinases (MMP). Altered MMP/TIMP ratios are frequently observed in several human diseases. During aging and disease progression, the extracellular matrix (ECM) undergoes structural changes in which elastin and collagens serve an essential role. MMPs and TIMPs significantly influence the ECM. Classically, elevated levels of TIMPs are suggested to result in ECM accumulation leading to fibrosis, whereas loss of TIMP responses leads to enhanced matrix proteolysis. Here, we outline the known roles of the most abundant TIMP, TIMP2, in pulmonary diseases but also discuss future perspectives in TIMP2 research that could impact the lungs. TIMP2 directly inhibits MMPs, in particular MMP2, but TIMP2 is also required for the activation of MMP2 through its interaction with MMP14. The protease and antiprotease imbalance of MMPs and TIMPs are extensively studied in diseases but recent discoveries suggest that TIMPs, specifically, TIMP2 could play other roles in aging and inflammation processes.

Pulmonary Fibrosis as a Result of Acute Lung Inflammation: Molecular Mechanisms, Relevant In Vivo Models, Prognostic and Therapeutic Approaches

Pulmonary fibrosis is a chronic progressive lung disease that steadily leads to lung architecture disruption and respiratory failure. The development of pulmonary fibrosis is mostly the result of previous acute lung inflammation, caused by a wide variety of etiological factors, not resolved over time and causing the deposition of fibrotic tissue in the lungs. Despite a long history of study and good coverage of the problem in the scientific literature, the effective therapeutic approaches for pulmonary fibrosis treatment are currently lacking. Thus, the study of the molecular mechanisms underlying the transition from acute lung inflammation to pulmonary fibrosis, and the search for new molecular markers and promising therapeutic targets to prevent pulmonary fibrosis development, remain highly relevant tasks. This review focuses on the etiology, pathogenesis, morphological characteristics and outcomes of acute lung inflammation as a precursor of pulmonary fibrosis; the pathomorphological changes in the lungs during fibrosis development; the known molecular mechanisms and key players of the signaling pathways mediating acute lung inflammation and pulmonary fibrosis, as well as the characteristics of the most common in vivo models of these processes. Moreover, the prognostic markers of acute lung injury severity and pulmonary fibrosis development as well as approved and potential therapeutic approaches suppressing the transition from acute lung inflammation to fibrosis are discussed.

Efficacy of a Probiotic and Herbal Supplement in Models of Lung Inflammation

Background: Gut microbiome dysbiosis is associated with lung disease through the gut-lung axis. Abundant proteobacteria increase MMP-9 and contribute to tissue proteolysis followed by neutrophil recruitment, lung tissue injury, and perpetuation of chronic lung disease. We sought to determine if a scientifically formulated probiotic and herbal supplement could attenuate neutrophilic inflammation and improve lung structure and function in models of lung inflammation. Methods: For in vitro experiments, epithelial cells exposed to proteobacteria were treated with resB—a blend of three probiotic Lactobacillus strains and turmeric, holy basil, and vasaka herbal extracts. For in vivo experimentation, mice exposed to pulmonary proteobacteria-derived lipopolysaccharide were treated by gavage with resB. Results: In vitro, the bacterial and herbal components of resB decreased activity of the MMP-9 pathway. Mice exposed to LPS and pre- and post-treated with resB had decreased neutrophil recruitment and inflammatory biomarkers in bronchoalveolar lavage fluid, serum, and lung tissue compared to untreated mice. Conclusions: This study describes the mechanisms and efficacy of probiotic and herbal blend in pre-clinical models of lung injury and inflammation.

The role of interleukin-33 in organ fibrosis

Interleukin (IL)-33 is highly expressed in the nucleus of cells present at barrier sites and signals via the ST2 receptor. IL-33 signalling via ST2 is essential for return to tissue homeostasis after acute inflammation, promoting fibrinogenesis and wound healing at injury sites. However, this wound-healing response becomes aberrant during chronic or sustained inflammation, leading to transforming growth factor beta (TGF-β) release, excessive extracellular matrix deposition, and fibrosis. This review addresses the role of the IL-33 pathway in fibrotic diseases of the lung, liver, gastrointestinal tract, skin, kidney and heart. In the lung and liver, IL-33 release leads to the activation of pro-fibrotic TGF-β, and in these sites, IL-33 has clear pro-fibrotic roles. In the gastrointestinal tract, skin, and kidney, the role of IL-33 is more complex, being both pro-fibrotic and tissue protective. Finally, in the heart, IL-33 serves cardioprotective functions by favouring tissue healing and preventing cardiomyocyte death. Altogether, this review indicates the presence of an unclear and delicate balance between resolving and pro-fibrotic capabilities of IL-33, which has a central role in the modulation of type 2 inflammation and fibrosis in response to tissue injury.

Role of matrix metalloprotease-2 and MMP-9 in experimental lung fibrosis in mice

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a diffuse parenchymal lung disease characterized by exuberant deposition of extracellular matrix (ECM) proteins in the lung interstitium, which contributes to substantial morbidity and mortality in IPF patients. Matrix metalloproteinases (MMPs) are a large family of zinc-dependent endopeptidases, many of which have been implicated in the regulation of ECM degradation in lung fibrosis. However, the roles of MMP-2 and -9 (also termed gelatinases A and B) have not yet been explored in lung fibrosis in detail.

METHODS

AdTGF-β1 was applied via orotracheal routes to the lungs of WT, MMP-2 KO, MMP-9 KO and MMP-2/-9 dKO mice on day 0 to induce lung fibrosis. Using hydroxyproline assay, FlexiVent based lung function measurement, histopathology, western blot and ELISA techniques, we analyzed MMP-2 and MMP-9 levels in BAL fluid and lung, collagen contents in lung and lung function in mice on day 14 and 21 post-treatment.

RESULT

IPF lung homogenates exhibited significantly increased levels of MMP-2 and MMP-9, relative to disease controls. Enzymatically active MMP-2 and MMP-9 was increased in lungs of mice exposed to adenoviral TGF-β1, suggesting a role for these metalloproteinases in lung fibrogenesis. However, we found that neither MMP-2 or MMP-9 nor combined MMP-2/-9 deletion had any effect on experimental lung fibrosis in mice.

CONCLUSION

Together, our data strongly suggest that both gelatinases MMP-2 and MMP-9 play only a subordinate role in experimental lung fibrosis in mice.

Molecular Clustering Analysis of Blood Biomarkers in World Trade Center Exposed Community Members with Persistent Lower Respiratory Symptoms

The destruction of the World Trade Center (WTC) on September 11, 2001 (9/11) released large amounts of toxic dusts and fumes into the air that exposed many community members who lived and/or worked in the local area. Many community members, defined as WTC survivors by the federal government, developed lower respiratory symptoms (LRS). We previously reported the persistence of these symptoms in patients with normal spirometry despite treatment with inhaled corticosteroids and/or long-acting bronchodilators. This report expands upon our study of this group with the goal to identify molecular markers associated with exposure and heterogeneity in WTC survivors with LRS using a selected plasma biomarker approach. Samples from WTC survivors with LRS (n = 73, WTCS) and samples from healthy control participants of the NYU Bellevue Asthma Registry (NYUBAR, n = 55) were compared. WTCS provided information regarding WTC dust exposure intensity. Hierarchical clustering of the linear biomarker data identified two clusters within WTCS and two clusters within NYUBAR controls. Comparison of the WTCS clusters showed that one cluster had significantly increased levels of circulating matrix metalloproteinases (MMP1, 2, 3, 8, 12, 13), soluble inflammatory receptors (receptor for advanced glycation end-products-RAGE, Interleukin-1 receptor antagonist (IL-1RA), suppression of tumorigenicity (ST)2, triggering receptor expressed on myeloid cells (TREM)1, IL-6Ra, tumor necrosis factor (TNF)RI, TNFRII), and chemokines (IL-8, CC chemokine ligand- CCL17). Furthermore, this WTCS cluster was associated with WTC exposure variables, ash at work, and the participant category workers; but not with the exposure variable WTC dust cloud at 9/11. A comparison of WTC exposure categorial variables identified that chemokines (CCL17, CCL11), circulating receptors (RAGE, TREM1), MMPs (MMP3, MMP12), and vascular markers (Angiogenin, vascular cell adhesion molecule-VCAM1) significantly increased in the more exposed groups. Circulating biomarkers of remodeling and inflammation identified clusters within WTCS and were associated with WTC exposure.

Regeneration or Repair? The Role of Alveolar Epithelial Cells in the Pathogenesis of Idiopathic Pulmonary Fibrosis (IPF)

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive interstitial lung disease (ILD) with unknown etiology in which gradual fibrotic scarring of the lungs leads to usual interstitial pneumonia (UIP) and, ultimately, to death. IPF affects three million people worldwide, and the only currently available treatments include the antifibrotic drugs nintedanib and pirfenidone, which effectively reduce fibrosis progression are, unfortunately, not effective in curing the disease. In recent years, the paradigm of IPF pathogenesis has shifted from a fibroblast-driven disease to an epithelium-driven disease, wherein, upon recurrent microinjuries, dysfunctional alveolar type II epithelial cells (ATII) are not only unable to sustain physiological lung regeneration but also promote aberrant epithelial–mesenchymal crosstalk. This creates a drift towards fibrosis rather than regeneration. In the context of this review article, we discuss the most relevant mechanisms involved in IPF pathogenesis with a specific focus on the role of dysfunctional ATII cells in promoting disease progression. In particular, we summarize the main causes of ATII cell dysfunction, such as aging, environmental factors, and genetic determinants. Next, we describe the known mechanisms of physiological lung regeneration by drawing a parallel between embryonic lung development and the known pathways involved in ATII-driven alveolar re-epithelization after injury. Finally, we review the most relevant interventional clinical trials performed in the last 20 years with the aim of underlining the urgency of developing new therapies against IPF that are not only aimed at reducing disease progression by hampering ECM deposition but also boost the physiological processes of ATII-driven alveolar regeneration.

Matrix Metalloproteinases and Their Inhibitors in Pulmonary Fibrosis: EMMPRIN/CD147 Comes into Play

Pulmonary fibrosis (PF) is characterized by aberrant extracellular matrix (ECM) deposition, activation of fibroblasts to myofibroblasts and parenchymal disorganization, which have an impact on the biomechanical traits of the lung. In this context, the balance between matrix metalloproteinases (MMPs) and their tissue inhibitors of metalloproteinases (TIMPs) is lost. Interestingly, several MMPs are overexpressed during PF and exhibit a clear profibrotic role (MMP-2, -3, -8, -11, -12 and -28), but a few are antifibrotic (MMP-19), have both profibrotic and antifibrotic capacity (MMP7), or execute an unclear (MMP-1, -9, -10, -13, -14) or unknown function. TIMPs are also overexpressed in PF; hence, the modulation and function of MMPs and TIMP are more complex than expected. EMMPRIN/CD147 (also known as basigin) is a transmembrane glycoprotein from the immunoglobulin superfamily (IgSF) that was first described to induce MMP activity in fibroblasts. It also interacts with other molecules to execute non-related MMP aactions well-described in cancer progression, migration, and invasion. Emerging evidence strongly suggests that CD147 plays a key role in PF not only by MMP induction but also by stimulating fibroblast myofibroblast transition. In this review, we study the structure and function of MMPs, TIMPs and CD147 in PF and their complex crosstalk between them.

Curcumin intervention during progressive fibrosis controls inflammatory cytokines and the fibrinolytic system in pulmonary fibrosis

Persistent injuries and chronic inflammation paired with dysregulated healing process in the lungs leads to scarring and stiffening of the tissue leading to a condition called pulmonary fibrosis. There is no efficacious therapy against the condition because of the poorly understood pathophysiology of the disease. Curcumin is well known anti-inflammatory natural compound and is shown to have beneficial effects in many diseases. It is also reported to show antifibrotic activities in pulmonary fibrosis. There are evidences that fibrinolytic system plays a crucial role in the development of pulmonary fibrosis. We aimed to see whether curcumin could regulate inflammation and fibrinolysis in murine model of pulmonary fibrosis. We prepared BLM induced pulmonary fibrosis model by administering BLM at a dose of 2 mg/ kg bodyweight. Curcumin (75 mg/kg body wt) was instilled intraperitoneally on different time points. The effect of curcumin on inflammatory cytokines and fibrinolytic system was studied using molecular biology techniques like RT-PCR, western blot and immunohistochemistry/immunofluorescence. We observed that BLM brought changes in the expressions of components in the fibrinolytic system, i.e. BLM favoured fibrin deposition by increasing the expression of PAI-1 (plasminogen activator inhibitor) and decreasing the expression of uPA (Urokinase plasminogen activator) and uPAR (Urokinase plasminogen activator receptor). We also demonstrate that curcumin could restore the normal expression of fibrinolytic components, uPA, uPAR and PAI-1. Curcumin could also minimize the expression of key enzymes in tissue remodeling in pulmonary fibrosis, MMP-2 and MMP-9, which were elevated in the BLM treated group. Our data suggest that curcumin exerts an anti-inflammatory and antifibrotic effect in lungs. We highlight curcumin as a feasible adjuvant therapy option against pulmonary fibrosis.

Construction of MicroRNA-mRNA Regulatory Network in the Molecular Mechanisms of Bleomycin-Induced Pulmonary Fibrosis

Bleomycin is a common antitumor agent used to treat many different types of malignancies; however, its main side effect is pulmonary fibrosis. The mechanism of bleomycin-induced pulmonary fibrosis (BIPF) has not been fully elucidated. Therefore, to further explore the molecular mechanisms of BIPF, we screened for microRNA (miRNA) and mRNA expression obtained from BIPF samples from the Gene Expression Omnibus database. Subsequently, we identified the differentially expressed miRNAs and genes that overlapped with the differentially expressed miRNAs target genes, predicted by using the miRWalk database selected as a candidate. The candidate genes were visualized based on Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes analyses. A protein-protein interaction network was constructed. Hub differentially expressed genes were selected and corresponding miRNAs to construct a miRNA-mRNA regulation network. Then, we chose three key miRNAs to study their regulatory relationship in bleomycin-induced pulmonary fibrosis. Finally, mouse lung epithelial cells TC-1 and MLE-12 were treated with bleomycin with qPCR to validate the results of three important hub genes and all key miRNAs. And dual-luciferase report experiment was carried out to verify the interaction of mmu-miR-1946a and serpina3n. The results revealed that the imbalance of matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) plays a pivotal role in the occurrence and development of BIPF. In addition, Serpina3n and mmu-miR-1946a were proved interaction and may be involved in the regulation of the balance between MMP-9 and TIMP-1. The experimental results also verify the analysis. Our findings provide new insights into the key mediators and pathways related to the molecular mechanisms of BIPF.

MMP-10 from M1 macrophages promotes pulmonary vascular remodeling and pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterized by muscularized pulmonary blood vessels, leading to right heart hypertrophy and cardiac failure. However, state-of-the-art therapeutics fail to target the ongoing remodeling process. Here, this study shows that matrix metalloproteinases (MMP)-1 and MMP-10 levels are increased in the medial layer of vessel wall, serum, and M1-polarized macrophages from patients with PAH and the lungs of monocrotaline- and hypoxia-induced PAH rodent models. MMP-10 regulates the malignant phenotype of pulmonary artery smooth muscle cells (PASMCs). The overexpression of active MMP-10 promotes PASMC proliferation and migration via upregulation of cyclin D1 and proliferating cell nuclear antigen, suggesting that MMP-10 produced by infiltrating macrophages contributes to vascular remodeling. Furthermore, inhibition of STAT1 inhibits hypoxia-induced MMP-10 but not MMP-1 expression in M1-polarized macrophages from patients with PAH. In conclusion, circulating MMP-10 could be used as a potential targeted therapy for PAH.

Matrix Metalloproteinase 7 Expression and Apical Epithelial Defects in Atp8b1 Mutant Mouse Model of Pulmonary Fibrosis

Abnormalities in airway epithelia and lung parenchyma are found in Atp8b1 mutant mice, which develop pulmonary fibrosis after hyperoxic insult. Microarray and ingenuity pathway analysis (IPA) show numerous transcripts involved in ciliogenesis are downregulated in 14-month (14 M) -old Atp8b1 mouse lung compared with wild-type C57BL/6. Lung epithelium of Atp8b1 mice demonstrate apical abnormalities of ciliated and club cells in the bronchial epithelium on transmission electron microscopy (TEM). Matrix metalloproteinase 7 (MMP7) regulates of ciliogenesis and is a biomarker for idiopathic pulmonary fibrosis (IPF) in humans. Mmp7 transcript and protein expression are significantly upregulated in 14 M Atp8b1 mutant mouse lung. MMP7 expression is also increased in bronchoalveolar lavage fluid (BAL). Immunohistochemistry is localized MMP7 to bronchial epithelial cells in the Atp8b1 mutant. In conclusion, MMP7 is upregulated in the aged Atp8b1 mouse model, which displays abnormal ciliated cell and club cell morphology. This mouse model can facilitate the exploration of the role of MMP7 in epithelial integrity and ciliogenesis in IPF. The Atp8b1 mutant mouse is proposed as a model for IPF.

Identification of three hub genes related to the prognosis of idiopathic pulmonary fibrosis using bioinformatics analysis

Background: Idiopathic pulmonary fibrosis (IPF) is a chronic respiratory disease characterized by peripheral distribution of bilateral pulmonary fibrosis that is more pronounced at the base. IPF has a short median survival time and a poor prognosis. Therefore, it is necessary to identify effective prognostic indicators to guide the treatment of patients with IPF. Methods: We downloaded microarray data of bronchoalveolar lavage cells from the Gene Expression Omnibus (GEO), containing 176 IPF patients and 20 controls. The top 5,000 genes in the median absolute deviation were classified into different color modules using weighted gene co-expression network analysis (WGCNA), and the modules significantly associated with both survival time and survival status were identified as prognostic modules. We used Lasso Cox regression and multivariate Cox regression to search for hub genes related to prognosis from the differentially expressed genes (DEGs) in the prognostic modules and constructed a risk model and nomogram accordingly. Moreover, based on the risk model, we divided IPF patients into high-risk and low-risk groups to determine the biological functions and immune cell subtypes associated with the prognosis of IPF using gene set enrichment analysis and immune cell infiltration analysis. Results: A total of 153 DEGs located in the prognostic modules, three (TPST1, MRVI1, and TM4SF1) of which were eventually defined as prognostic hub genes. A risk model was constructed based on the expression levels of the three hub genes, and the accuracy of the model was evaluated using time-dependent receiver operating characteristic (ROC) curves. The areas under the curve for 1-, 2-, and 3-year survival rates were 0.862, 0.885, and 0.833, respectively. The results of enrichment analysis showed that inflammation and immune processes significantly affected the prognosis of patients with IPF. The degree of mast and natural killer (NK) cell infiltration also increases the prognostic risk of IPF. Conclusions: We identified three hub genes as independent molecular markers to predict the prognosis of patients with IPF and constructed a prognostic model that may be helpful in promoting therapeutic gains for IPF patients.

Inflammation, Ageing and Diseases of the Lung: Potential therapeutic strategies from shared biological pathways

Lung diseases disproportionately affect elderly individuals. The lungs form a unique environment: a highly elastic organ with gaseous exchange requiring the closest proximity of inhaled air containing harmful agents and the circulating blood volume. The lungs are highly susceptible to senescence, with age and "inflammageing" creating a pro-inflammatory environment with a reduced capacity to deal with challenges. Whilst lung diseases may have disparate causes, the burden of ageing and inflammation provides a common process which can exacerbate seemingly unrelated pathologies. However, these shared pathways may also provide a common route to treatment, with increased interest in drugs which target ageing processes across respiratory diseases. In this review, we will examine the evidence for the increased burden of lung disease in older adults, the structural and functional changes seen with advancing age and assess what our expanding knowledge of inflammation and ageing pathways could mean for the treatment of lung disease.

Core genes involved in the regulation of acute lung injury and their association with COVID-19 and tumor progression: A bioinformatics and experimental study

Acute lung injury (ALI) is a specific form of lung damage caused by different infectious and non-infectious agents, including SARS-CoV-2, leading to severe respiratory and systemic inflammation. To gain deeper insight into the molecular mechanisms behind ALI and to identify core elements of the regulatory network associated with this pathology, key genes involved in the regulation of the acute lung inflammatory response (Il6, Ccl2, Cat, Serpine1, Eln, Timp1, Ptx3, Socs3) were revealed using comprehensive bioinformatics analysis of whole-genome microarray datasets, functional annotation of differentially expressed genes (DEGs), reconstruction of protein-protein interaction networks and text mining. The bioinformatics data were validated using a murine model of LPS-induced ALI; changes in the gene expression patterns were assessed during ALI progression and prevention by anti-inflammatory therapy with dexamethasone and the semisynthetic triterpenoid soloxolone methyl (SM), two agents with different mechanisms of action. Analysis showed that 7 of 8 revealed ALI-related genes were susceptible to LPS challenge (up-regulation: Il6, Ccl2, Cat, Serpine1, Eln, Timp1, Socs3; down-regulation: Cat) and their expression was reversed by the pre-treatment of mice with both anti-inflammatory agents. Furthermore, ALI-associated nodal genes were analysed with respect to SARS-CoV-2 infection and lung cancers. The overlap with DEGs identified in postmortem lung tissues from COVID-19 patients revealed genes (Saa1, Rsad2, Ifi44, Rtp4, Mmp8) that (a) showed a high degree centrality in the COVID-19-related regulatory network, (b) were up-regulated in murine lungs after LPS administration, and (c) were susceptible to anti-inflammatory therapy. Analysis of ALI-associated key genes using The Cancer Genome Atlas showed their correlation with poor survival in patients with lung neoplasias (Ptx3, Timp1, Serpine1, Plaur). Taken together, a number of key genes playing a core function in the regulation of lung inflammation were found, which can serve both as promising therapeutic targets and molecular markers to control lung ailments, including COVID-19-associated ALI.

Time-dependent propensity-matched general population study of the effects of statin use on cancer risk in an interstitial lung disease and pulmonary fibrosis cohort

OBJECTIVE

To determine the effect of statins on risk of cancer in patients with interstitial lung disease (ILD) and pulmonary fibrosis.

SETTING

We retrospectively enrolled patients with ILD and pulmonary fibrosis and divided them into two cohorts by statin use (statin users (n=10 036) and statin non-users (n=10 036)).

PARTICIPANTS

We selected patients with ILD and pulmonary fibrosis (N=53 862) from Taiwan's National Health Insurance Research Database. Time-dependent Cox models were used to compare risk of cancer of propensity-matched statin users and non-users. Cumulative cancer incidence was analysed through Cox proportional regression. We calculated adjusted HRs (aHRs) and their 95% CIs for cancer after adjusting for sex, age, comorbidities, and use of inhaled corticosteroids, oral steroids and statins.

RESULTS

Compared with statin non-users, the aHRs (95% CIs) for statin users were 0.60 (0.55 to 0.65) for cancer, 0.52 (0.35 to 0.78) for haematological malignancy, 0.52 (0.38 to 0.72) for cancer of the head and neck, 0.73 (0.59 to 0.89) for colorectal cancer, 0.34 (0.26 to 0.43) for liver cancer, 0.39 (0.23 to 0.67) for pancreatic cancer, 0.40 (0.17 to 0.96) for skin cancer, 0.67 (0.52 to 0.87) for breast cancer, 0.27 (0.14 to 0.54) for cervical cancer, 0.37 (0.30 to 0.46) for other immunological cancers, 0.73 (0.54 to 0.98) for bladder/kidney cancer and 0.88 (0.71 to 1.09) for lung cancer.

CONCLUSION

Statin use is associated with lower risk of cancer in the ILD and pulmonary fibrosis cohort.

Involvement of 4-hydroxy-2-nonenal in the pathogenesis of pulmonary fibrosis

Pulmonary fibrosis is a chronic progressive disease with high incidence, prevalence, and mortality rates worldwide. It is characterized by excessive accumulation of extracellular matrix in the lung parenchyma. The cellular and molecular mechanisms involved in its pathogenesis are complex, and some are still unknown. Several studies indicate that oxidative stress, characterized by overproduction of 4-hydroxy-2-nonenal (4-HNE), is an important player in pulmonary fibrosis. 4-HNE is a highly reactive compound derived from polyunsaturated fatty acids that can react with proteins, phospholipids, and nucleic acids. Thus, many of the altered cellular mechanisms that contribute to this disease can be explained by the participation of 4-HNE. Here, we summarize the current knowledge on the molecular states and signal transduction pathways that contribute to the pathogenesis of pulmonary fibrosis. Furthermore, we describe the participation of 4-HNE in various mechanisms involved in pulmonary fibrosis development, with a focus on the cell populations involved in the initiation, development, and maintenance of the fibrotic process, mainly alveolar cells, endothelial cells, macrophages, and inflammatory cells. Due to its characteristic activity as a second messenger, 4-HNE, in addition to being a consequence of oxidative stress, can support maintenance of the inflammatory and fibrotic process by spreading the effects of reactive oxygen species (ROS). Thus, regulation of 4-HNE levels could be a viable strategy to reduce its effects on the mechanisms involved in pulmonary fibrosis development.

Comprehensive Analysis of the Systemic Transcriptomic Alternations and Inflammatory Response during the Occurrence and Progress of COVID-19

The pandemic of the coronavirus disease 2019 (COVID-19) has posed huge threats to healthcare systems and the global economy. However, the host response towards COVID-19 on the molecular and cellular levels still lacks full understanding and effective therapies are in urgent need. Here, we integrate three datasets, GSE152641, GSE161777, and GSE157103. Compared to healthy people, 314 differentially expressed genes were identified, which were mostly involved in neutrophil degranulation and cell division. The protein-protein network was established and two significant subsets were filtered by MCODE: ssGSEA and CIBERSORT, which comprehensively revealed the alternation of immune cell abundance. Weighted gene coexpression network analysis (WGCNA) as well as GO and KEGG analyses unveiled the role of neutrophils and T cells during the progress of the disease. Based on the hospital-free days after 45 days of follow-up and statistical methods such as nonnegative matrix factorization (NMF), submap, and linear correlation analysis, 31 genes were regarded as the signature of the peripheral blood of COVID-19. Various immune cells were identified to be related to the prognosis of the patients. Drugs were predicted for the genes in the signature by DGIdb. Overall, our study comprehensively revealed the relationship between the inflammatory response and the disease course, which provided strategies for the treatment of COVID-19.

Understanding idiopathic pulmonary fibrosis - Clinical features, molecular mechanism and therapies

Idiopathic pulmonary fibrosis (IPF) is a chronic lung fibrosing disease with high prevalence that has a prognosis worse than many cancers. There has been a recent influx of new observations aimed at explaining the mechanisms responsible for the initiation and progression of pulmonary fibrosis. However, despite this, the pathogenesis of the disease is largely unclear. Recent progress has been made in the characterization of specific pathologic and clinical features that have enhanced the understanding of pathologically activated molecular pathways during the onset and progression of IPF. This review highlights several of the advances that have been made and focus on the pathobiology of IPF. The work also details the different factors that are responsible for the disposition of the disease - these may be internal factors such as cellular mechanisms and genetic alterations, or they may be external factors from the environment. The changes that primarily occur in epithelial cells and fibroblasts that lead to the activation of profibrotic pathways are discussed in depth. Finally, a complete repertoire of the treatment therapies that have been used in the past as well as future medications and therapies is provided.

Molecular Biomarkers in Idiopathic Pulmonary Fibrosis: State of the Art and Future Directions

Idiopathic pulmonary fibrosis (IPF), the most lethal form of interstitial pneumonia of unknown cause, is associated with a specific radiological and histopathological pattern (the so-called "usual interstitial pneumonia" pattern) and has a median survival estimated to be between 3 and 5 years after diagnosis. However, evidence shows that IPF has different clinical phenotypes, which are characterized by a variable disease course over time. At present, the natural history of IPF is unpredictable for individual patients, although some genetic factors and circulating biomarkers have been associated with different prognoses. Since in its early stages, IPF may be asymptomatic, leading to a delayed diagnosis. Two drugs, pirfenidone and nintedanib, have been shown to modify the disease course by slowing down the decline in lung function. It is also known that 5-10% of the IPF patients may be affected by episodes of acute and often fatal decline. The acute worsening of disease is sometimes attributed to identifiable conditions, such as pneumonia or heart failure; but many of these events occur without an identifiable cause. These idiopathic acute worsenings are termed acute exacerbations of IPF. To date, clinical biomarkers, diagnostic, prognostic, and theranostic, are not well characterized. However, they could become useful tools helping facilitate diagnoses, monitoring disease progression and treatment efficacy. The aim of this review is to cover molecular mechanisms underlying IPF and research into new clinical biomarkers, to be utilized in diagnosis and prognosis, even in patients treated with antifibrotic drugs.

Type-1 immunity and endogenous immune regulators predominate in the airway transcriptome during chronic lung allograft dysfunction

Chronic lung allograft dysfunction (CLAD) remains the major complication limiting long-term survival among lung transplant recipients (LTRs). Limited understanding of CLAD immunopathogenesis and a paucity of biomarkers remain substantial barriers for earlier detection and therapeutic interventions for CLAD. We hypothesized the airway transcriptome would reflect key immunologic changes in disease. We compared airway brush-derived transcriptomic signatures in CLAD (n = 24) versus non-CLAD (n = 21) LTRs. A targeted assessment of the proteome using concomitant bronchoalveolar lavage (BAL) fluid for 24 cytokines/chemokines and alloimmune T cell responses was performed to validate the airway transcriptome. We observed an airway transcriptomic signature of differential genes expressed (DGEs) in CLAD marked by Type-1 immunity and striking upregulation of two endogenous immune regulators: indoleamine 2, 3 dioxygenase 1 (IDO-1) and tumor necrosis factor receptor superfamily 6B (TNFRSF6B). Advanced CLAD staging was associated with a more intense airway transcriptome signature. In a validation cohort using the identified signature, we found an area under the curve (AUC) of 0.77 for CLAD LTRs. Targeted proteomic analyses revealed a predominant Type-1 profile with detection of IFN-γ, TNF-α, and IL-1β as dominant CLAD cytokines, correlating with the airway transcriptome. The airway transcriptome provides novel insights into CLAD immunopathogenesis and biomarkers that may impact diagnosis of CLAD.

Airspace Macrophages and Monocytes Exist in Transcriptionally Distinct Subsets in Healthy Adults

Rationale: Macrophages are the most abundant immune cell in the alveoli and small airways and are traditionally viewed as a homogeneous population during health. Whether distinct subsets of airspace macrophages are present in healthy humans is unknown. Single-cell RNA sequencing allows for examination of transcriptional heterogeneity between cells and between individuals. Understanding the conserved repertoire of airspace macrophages during health is essential to understanding cellular programing during disease.Objectives: We sought to determine the transcriptional heterogeneity of human cells obtained from BAL of healthy adults.Methods: Ten subjects underwent bronchoscopy with BAL. Cells from lavage were subjected to single-cell RNA sequencing. Unique cell populations and putative functions were identified. Transcriptional profiles were compared across individuals.Measurements and Main Results: We identify two novel subgroups of resident airspace macrophages-defined by proinflammatory and metallothionein gene expression profiles. We define subsets of monocyte-like cells and compare them with peripheral blood mononuclear cells. Finally, we compare global macrophage and monocyte programing between males and females.Conclusions: Healthy human airspaces contain multiple populations of myeloid cells that are highly conserved between individuals and between sexes. Resident macrophages make up the largest population and include novel subsets defined by inflammatory and metal-binding profiles. Monocyte-like cells within the airspaces are transcriptionally aligned with circulating blood cells and include a rare population defined by expression of cell-matrix interaction genes. This study is the first to delineate the conserved heterogeneity of airspace immune cells during health and identifies two previously unrecognized macrophage subsets.

Therapeutic targets in lung tissue remodelling and fibrosis

Structural changes involving tissue remodelling and fibrosis are major features of many pulmonary diseases, including asthma, chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF). Abnormal deposition of extracellular matrix (ECM) proteins is a key factor in the development of tissue remodelling that results in symptoms and impaired lung function in these diseases. Tissue remodelling in the lungs is complex and differs between compartments. Some pathways are common but tissue remodelling around the airways and in the parenchyma have different morphologies. Hence it is critical to evaluate both common fibrotic pathways and those that are specific to different compartments; thereby expanding the understanding of the pathogenesis of fibrosis and remodelling in the airways and parenchyma in asthma, COPD and IPF with a view to developing therapeutic strategies for each. Here we review the current understanding of remodelling features and underlying mechanisms in these major respiratory diseases. The differences and similarities of remodelling are used to highlight potential common therapeutic targets and strategies. One central pathway in remodelling processes involves transforming growth factor (TGF)-β induced fibroblast activation and myofibroblast differentiation that increases ECM production. The current treatments and clinical trials targeting remodelling are described, as well as potential future directions. These endeavours are indicative of the renewed effort and optimism for drug discovery targeting tissue remodelling and fibrosis.

Differential Responses to Targeting Matrix Metalloproteinase 9 in Idiopathic Pulmonary Fibrosis

Rationale: Aberrant lung remodeling in idiopathic pulmonary fibrosis (IPF) is characterized by elevated MMP9 (matrix metalloproteinase 9) expression, but the precise role of this matrix metalloproteinase in this disease has yet to be fully elucidated.Objectives: To evaluate antifibrotic effects of MMP9 inhibition on IPF.Methods: Quantitative genomic, proteomic, and functional analyses both in vitro and in vivo were used to determine MMP9 expression in IPF cells and the effects of MMP9 inhibition on profibrotic mechanisms.Measurements and Main Results: In the present study, we demonstrate that MMP9 expression was increased in airway basal cell (ABC)-like cells from IPF lungs compared with ABC cells from normal lungs. The inhibition of MMP9 activity with an anti-MMP9 antibody, andecaliximab, blocked TGF-β1 (transforming growth factor β1)-induced Smad2 phosphorylation. However, in a subset of cells from patients with IPF, TGF-β1 activation in their ABC-like cells was unaffected or enhanced by MMP9 blockade (i.e., nonresponders). Further analysis of nonresponder ABC-like cells treated with andecaliximab revealed an association with type 1 IFN expression, and the addition of IFNα to these cells modulated both MMP9 expression and TGF-β1 activation. Finally, the inhibition of MMP9 ameliorated pulmonary fibrosis induced by responder lung cells but not a nonresponder in a humanized immunodeficient mouse model of IPF.Conclusions: Together, these data demonstrate that MMP9 regulates the activation of ABC-like cells in IPF and that targeting this MMP might be beneficial to a subset of patients with IPF who show sufficient expression of type 1 IFNs.

Proteomic profiling identifies key differences between inter-stage infants with single ventricle heart disease and healthy controls

Despite significant morbidity among infants with single ventricle heart disease (SVHD), clinical monitoring is limited by poor understanding of the underlying pathobiology. Proteomics can identify novel biomarkers and important pathways in complex disease. No prior study has evaluated whether the proteome of SVHD infants differs from healthy controls, how it shifts after stage 2 palliation, or whether differences can predict post-operative outcomes. We present a prospective cohort study of cardiovascular proteomic phenotyping in infants with SVHD undergoing stage 2 palliation. Twenty-nine pre-stage-2 SVHD infants and 25 healthy controls were enrolled. Outcomes included postoperative hypoxemia and endotracheal intubation time. Serum samples were drawn pre-operatively (systemic and pulmonary vein) and at 24 hours postoperation. Targeted cardiovascular proteomic analysis included 184 proteins. Partial least squares discriminant analysis distinguished cases from controls (Accuracy = 0.98, R² = 0.93, Q² = 0.81) with decreased inflammatory mediators and increased modulators of vascular tone. Partial least squares discriminant analysis also distinguished cases pre-operation vs. post-operation (Accuracy=0.98, R²=0.99, Q² = 0.92) with postoperative increase in both inflammatory and vascular tone mediators. Pre-operation pulmonary vein tissue inhibitor of metalloproteinase-1 (1.8x-fold, p=1.6 × 10^-4) and nidogen-1 (1.5x-fold, p=1.7 × 10^-4) were higher in subjects with longer endotracheal intubation time. Postoperation matrix metalloproteinase 7 levels were higher in subjects with greater postoperative hypoxemia (1.5x-fold, P= 1.97 × 10^-5). Proteomic analysis identifies significant changes among SVHD infants pre- and post-stage 2, and healthy controls. Tissue inhibitor of metalloproteinase-1, nidogen-1, and matrix metalloproteinase 7 levels are higher in SVHD cases with greater morbidity suggesting an important role for regulation of extracellular matrix production. Proteomic profiling may identify high-risk SVHD infants.

Role of various imbalances centered on alveolar epithelial cell/fibroblast apoptosis imbalance in the pathogenesis of idiopathic pulmonary fibrosis

There have been recent extensive studies and rapid advancement on the pathogenesis underlying idiopathic pulmonary fibrosis (IPF), and intricate pathogenesis of IPF has been suggested. The purpose of this study was to clarify the logical relationship between these mechanisms. An extensive search was undertaken of the PubMed using the following keywords: “etiology,” “pathogenesis,” “alveolar epithelial cell (AEC),” “fibroblast,” “lymphocyte,” “macrophage,” “epigenomics,” “histone,” acetylation,” “methylation,” “endoplasmic reticulum stress,” “mitochondrial dysfunction,” “telomerase,” “proteases,” “plasminogen,” “epithelial-mesenchymal transition,” “oxidative stress,” “inflammation,” “apoptosis,” and “idiopathic pulmonary fibrosis.” This search covered relevant research articles published up to April 30, 2020. Original articles, reviews, and other articles were searched and reviewed for content; 240 highly relevant studies were obtained after screening. IPF is likely the result of complex interactions between environmental, genetic, and epigenetic factors: environmental exposures affect epigenetic marks; epigenetic processes translate environmental exposures into the regulation of chromatin; epigenetic processes shape gene expression profiles; in turn, an individual's genetic background determines epigenetic marks; finally, these genetic and epigenetic factors act in concert to dysregulate gene expression in IPF lung tissue. The pathogenesis of IPF involves various imbalances including endoplasmic reticulum, telomere length homeostasis, mitochondrial dysfunction, oxidant/antioxidant imbalance, Th1/Th2 imbalance, M1–M2 polarization of macrophages, protease/antiprotease imbalance, and plasminogen activation/inhibition imbalance. These affect each other, promote each other, and ultimately promote AEC/fibroblast apoptosis imbalance directly or indirectly. Excessive AEC apoptosis and impaired apoptosis of fibroblasts contribute to fibrosis. IPF is likely the result of complex interactions between environmental, genetic, and epigenetic factors. The pathogenesis of IPF involves various imbalances centered on AEC/fibroblast apoptosis imbalance.

Matrix metalloproteinase-2, -7, and -9 activities in dogs with idiopathic pulmonary fibrosis compared to healthy dogs and dogs with other respiratory diseases

BACKGROUND

Canine idiopathic pulmonary fibrosis (CIPF) is a chronic, interstitial lung disease that mainly affects West Highland white terriers (WHWTs) and is characterized by excessive deposition of extracellular matrix (ECM) in the lung. Matrix metalloproteinases (MMPs) participate in remodeling of ECM.

OBJECTIVES

To compare metalloproteinase-2, -7 and -9 activities in blood or bronchoalveolar lavage fluid (BALF) samples or both of CIPF WHWTs with healthy WHWTs, healthy dogs of other breeds, and dogs with other lung diseases and determine if these MMPs could be used as diagnostic and prognostic markers for CIPF.

ANIMALS

Forty-four CIPF WHWTs, 24 dogs with chronic bronchitis (CB), 17 with eosinophilic bronchopneumopathy (EBP), 10 with bacterial pneumonia, 39 healthy WHWTs, and 35 healthy dogs of other breeds.

METHODS

Cross-sectional observational study. Pro-MMP and active MMP activities were analyzed by zymography.

RESULTS

In serum, significantly higher (P < .01) pro-MMP-7 activities were observed in CIPF WHWTs compared to healthy dogs of other breeds, dogs with CB and dogs with EBP. In BALF of CIPF WHWTs, both pro-MMP-9 and pro-MMP-2 activities were significantly higher (P < .01) compared to healthy WHWTs, but these differences were not detected in plasma. The CIPF WHWTs had significantly higher (P < .05) activities of pro-MMP-9 compared to dogs with CB and of pro-MMP-2 compared to dogs with CB and EBP. No statistically significant prognostic factors were observed in CIPF WHWTs.

CONCLUSIONS AND CLINICAL RELEVANCE

Serum MMP-7 and BALF MMP-2 and -9 potentially may be useful diagnostic markers but not prognostic markers for CIPF.

Revisiting matrix metalloproteinase 12: its role in pathophysiology of asthma and related pulmonary diseases

PURPOSE OF REVIEW

Matrix metalloproteinases (MMPs) are a family of over 20 zinc-dependent proteases with different biological and pathological activities, and many have been implicated in several diseases. Although nonselective MMP inhibitors are known to induce serious side-effects, targeting individual MMPs may offer a safer therapeutic potential for several diseases. Hence, we provide a concise overview on MMP-12, given its association with pulmonary diseases, including asthma, chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis, and other progressive pulmonary fibrosis (PPF), which may also occur in coronavirus disease 2019.

RECENT FINDINGS

In asthma, COPD, and PPF, increased MMP-12 levels have been associated with inflammation and/or structural changes within the lungs and negatively correlated with functional parameters. Increased pulmonary MMP-12 levels and MMP-12 gene expression have been related to disease severity in asthma and COPD. Targeting MMP-12 showed potential in animal models of pulmonary diseases but human data are still very scarce.

SUMMARY

Although there may be a potential role of MMP-12 in asthma, COPD and PPF, several pathophysiological aspects await elucidation. Targeting MMP-12 may provide further insights into MMP-12 related mechanisms and how this translates into clinical outcomes; this warrants further research.

Identification of Pro-Fibrotic Macrophage Populations by Single-Cell Transcriptomic Analysis in West Highland White Terriers Affected With Canine Idiopathic Pulmonary Fibrosis

Canine idiopathic pulmonary fibrosis (CIPF) affects old dogs from the West Highland white terrier (WHWT) breed and mimics idiopathic pulmonary fibrosis (IPF) in human. The disease results from deposition of fibrotic tissue in the lung parenchyma causing respiratory failure. Recent studies in IPF using single-cell RNA sequencing (scRNA-seq) revealed the presence of profibrotic macrophage populations in the lung, which could be targeted for therapeutic purpose. In dogs, scRNA-seq was recently validated for the detection of cell populations in bronchoalveolar lavage fluid (BALF) from healthy dogs. Here we used the scRNA-seq to characterize disease-related heterogeneity within cell populations of macrophages/monocytes (Ma/Mo) in the BALF from five WHWTs affected with CIPF in comparison with three healthy WHWTs. Gene set enrichment analysis was also used to assess pro-fibrotic capacities of Ma/Mo populations. Five clusters of Ma/Mo were identified. Gene set enrichment analyses revealed the presence of pro-fibrotic monocytes in higher proportion in CIPF WHWTs than in healthy WHWTs. In addition, monocyte-derived macrophages enriched in pro-fibrotic genes in CIPF compared with healthy WHWTs were also identified. These results suggest the implication of Ma/Mo clusters in CIPF processes, although, further research is needed to understand their role in disease pathogenesis. Overexpressed molecules associated with pulmonary fibrosis processes were also identified that could be used as biomarkers and/or therapeutic targets in the future.