Mir-155-5p targets TP53INP1 to promote proliferative phenotype in hypersensitivity pneumonitis lung fibroblasts.

Background: Hypersensitivity pneumonitis (HP) is an inflammatory disorder affecting lung parenchyma and often evolves into fibrosis (fHP). The altered regulation of genes involved in the pathogenesis of the disease is not well comprehended, while the role of microRNAs in lung fibroblasts remains unexplored. Methods: We used integrated bulk RNA-Seq and enrichment pathway bioinformatic analyses to identify differentially expressed (DE)-miRNAs and genes (DEGs) associated with HP lungs. In vitro, we evaluated the expression and potential role of miR-155-5p in the phenotype of fHP lung fibroblasts. Loss and gain assays were used to demonstrate the impact of miR-155-5p on fibroblast functions. In addition, mir-155-5p and its target TP53INP1 were analyzed after treatment with TGF-ß, IL-4, and IL-17A. Results: We found around 50 DEGs shared by several databases that differentiate HP from control and IPF lungs, constituting a unique HP lung transcriptional signature. Additionally, we reveal 18 DE-miRNAs that may regulate these DEGs. Among the candidates likely associated with HP pathogenesis was miR-155-5p. Our findings indicate that increased miR-155-5p in fHP fibroblasts coincides with reduced TP53INP1 expression, high proliferative capacity, and a lack of senescence markers compared to IPF fibroblasts. Induced overexpression of miR-155-5p in normal fibroblasts remarkably increases the proliferation rate and decreases TP53INP1 expression. Conversely, miR-155-5p inhibition reduces proliferation and increases senescence markers. TGF-ß, IL-4, and IL-17A stimulated miR-155-5p overexpression in HP lung fibroblasts. Conclusion: Our findings suggest a distinctive signature of 53 DEGs in HP, including CLDN18, EEF2, CXCL9, PLA2G2D, and ZNF683, as potential targets for future studies. Likewise, 18 miRNAs, including miR-155-5p, could be helpful to establish differences between these two pathologies. The overexpression of miR-155-5p and downregulation of TP53INP1 in fHP lung fibroblasts may be involved in his proliferative and profibrotic phenotype. These findings may help differentiate and characterize their pathogenic features and understand their role in the disease.

Hypoxia Induces Alterations in the Circadian Rhythm in Patients with Chronic Respiratory Diseases.

The function of the circadian cycle is to determine the natural 24 h biological rhythm, which includes physiological, metabolic, and hormonal changes that occur daily in the body. This cycle is controlled by an internal biological clock that is present in the body's tissues and helps regulate various processes such as sleeping, eating, and others. Interestingly, animal models have provided enough evidence to assume that the alteration in the circadian system leads to the appearance of numerous diseases. Alterations in breathing patterns in lung diseases can modify oxygenation and the circadian cycles; however, the response mechanisms to hypoxia and their relationship with the clock genes are not fully understood. Hypoxia is a condition in which the lack of adequate oxygenation promotes adaptation mechanisms and is related to several genes that regulate the circadian cycles, the latter because hypoxia alters the production of melatonin and brain physiology. Additionally, the lack of oxygen alters the expression of clock genes, leading to an alteration in the regularity and precision of the circadian cycle. In this sense, hypoxia is a hallmark of a wide variety of lung diseases. In the present work, we intended to review the functional repercussions of hypoxia in the presence of asthma, chronic obstructive sleep apnea, lung cancer, idiopathic pulmonary fibrosis, obstructive sleep apnea, influenza, and COVID-19 and its repercussions on the circadian cycles.

Organic synthesis of 1,2-dipalmitoyl-rac-glycero-3-phosphatidylethanolamine and its effect on the induction of apoptosis in normal human lung fibroblasts.

BACKGROUND /OBJECTIVE: The phospholipid 1,2-dipalmitoyl-rac-glycero-3-phosphatidylethanolamine (PE) comprises two fatty acid chains: glycerol, phosphate, and ethanolamine. PE participates in critical cellular processes such as apoptosis and autophagy, which places it as a target for designing new therapeutic alternatives in diseases such as pulmonary fibrosis. Therefore, this study aimed obtain PE through a six-step organic synthesis pathway and determine its biological effect on apoptosis induction in normal human lung fibroblasts (NHLF). METHODOLOGY: The first step of the organic synthesis route began with protected glycerol that was benzylated at sn-3; later, it was deprotected to react with palmitic acid at sn-1, sn-2. To remove the benzyl group, hydrogenation was performed with palladium on carbon (Pd/C); subsequently, the molecule was phosphorylated in sn-3 with phosphorus oxychloride and triethylamine, and the intermediate was hydrolyzed in an acid medium to obtain the final compound. After PE synthesis, apoptosis assessment was performed: apoptosis was induced using exposure to annexin V-FITC/propidium iodide-ECD (PI) and quantified using flow cytometry. The experiments were performed in three NHLF cell lines with different concentrations of PE 10, 100 and 1000 µg/mL for 24 and 48 h. RESULTS: The PE obtained by organic synthesis presented a melting point of 190-192 °C, a purity of 95%, and a global yield of 8%. The evaluation of apoptosis with flow cytometry showed that at 24 h, exposure to PE 10, 100, and 1000 µg/mL induces early apoptosis in 19.42%- 25.54%, while late apoptosis was only significant P < 0.05 in cells challenged with 100 µg/mL PE. At 48 h, NHLF exposed to PE 10, 100, and 1000 µg/mL showed decreasing early apoptosis: 28.69-32.16%, 12.59-18.84%, and 10.91-12.61%, respectively. The rest of the NHLF exposed to PE showed late apoptosis: 12.03-16-42%, 11.04-15.94%, and 49.23-51.28%. Statistical analysis showed a significance P < 0.05 compared to the control. CONCLUSION: The organic synthesis route of PE allows obtaining rac-1,2-O-Dipalmitoyl-glycero-3-phosphoethanolamine (1), which showed an apoptotic effect on NHLF.

Absence of HDAC3 by Matrix Stiffness Promotes Chromatin Remodeling and Fibroblast Activation in Idiopathic Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a chronic and fatal disease characterized by progressive and irreversible lung scarring associated with persistent activation of fibroblasts. Epigenetics could integrate diverse microenvironmental signals, such as stiffness, to direct persistent fibroblast activation. Histone modifications by deacetylases (HDAC) may play an essential role in the gene expression changes involved in the pathological remodeling of the lung. Particularly, HDAC3 is crucial for maintaining chromatin and regulating gene expression, but little is known about its role in IPF. In the study, control and IPF-derived fibroblasts were used to determine the influence of HDAC3 on chromatin remodeling and gene expression associated with IPF signature. Additionally, the cells were grown on hydrogels to mimic the stiffness of a fibrotic lung. Our results showed a decreased HDAC3 in the nucleus of IPF fibroblasts, which correlates with changes in nucleus size and heterochromatin loss. The inhibition of HDAC3 with a pharmacological inhibitor causes hyperacetylation of H3K9 and provokes an increased expression of Col1A1, ACTA2, and p21. Comparable results were found in hydrogels, where matrix stiffness promotes the loss of nuclear HDAC3 and increases the profibrotic signature. Finally, latrunculin b was used to confirm that changes by stiffness depend on the mechanotransduction signals. Together, these results suggest that HDAC3 could be a link between epigenetic mechanisms and the fibrotic microenvironment.

Functional Repercussions of Hypoxia-Inducible Factor-2α in Idiopathic Pulmonary Fibrosis.

Hypoxia and hypoxia-inducible factors (HIFs) are essential in regulating several cellular processes, such as survival, differentiation, and the cell cycle; this adaptation is orchestrated in a complex way. In this review, we focused on the impact of hypoxia in the physiopathology of idiopathic pulmonary fibrosis (IPF) related to lung development, regeneration, and repair. There is robust evidence that the responses of HIF-1α and -2α differ; HIF-1α participates mainly in the acute phase of the response to hypoxia, and HIF-2α in the chronic phase. The analysis of their structure and of different studies showed a high specificity according to the tissue and the process involved. We propose that hypoxia-inducible transcription factor 2a (HIF-2α) is part of the persistent aberrant regeneration associated with developing IPF.

Effect of Hypoxia in the Transcriptomic Profile of Lung Fibroblasts from Idiopathic Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is an aging-associated disease characterized by exacerbated extracellular matrix deposition that disrupts oxygen exchange. Hypoxia and its transcription factors (HIF-1α and 2α) influence numerous circuits that could perpetuate fibrosis by increasing myofibroblasts differentiation and by promoting extracellular matrix accumulation. Therefore, this work aimed to elucidate the signature of hypoxia in the transcriptomic circuitry of IPF-derived fibroblasts. To determine this transcriptomic signature, a gene expression analysis with six lines of lung fibroblasts under normoxia or hypoxia was performed: three cell lines were derived from patients with IPF, and three were from healthy donors, a total of 36 replicates. We used the Clariom D platform, which allows us to evaluate a huge number of transcripts, to analyze the response to hypoxia in both controls and IPF. The control's response is greater by the number of genes and complexity. In the search for specific genes responsible for the IPF fibroblast phenotype, nineteen dysregulated genes were found in lung fibroblasts from IPF patients in hypoxia (nine upregulated and ten downregulated). In this sense, the signaling pathways revealed to be affected in the pulmonary fibroblasts of patients with IPF may represent an adaptation to chronic hypoxia.

Lack of ZNF365 Drives Senescence and Exacerbates Experimental Lung Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is characterized by aberrant activation of the alveolar epithelium, the expansion of the fibroblast population, and the accumulation of extracellular matrix. Global gene expression of human lung fibroblasts stimulated with TGFß-1, a strong fibrotic mediator revealed the overexpression of ZNF365, a zinc finger protein implicated in cell cycle control and telomere stabilization. We evaluated the expression and localization of ZNF365 in IPF lungs and in the fibrotic response induced by bleomycin in WT and deficient mice of the orthologous gene Zfp365. In IPF, ZNF365 was overexpressed and localized in fibroblasts/myofibroblasts and alveolar epithelium. Bleomycin-induced lung fibrosis showed an upregulation of Zfp365 localized in lung epithelium and stromal cell populations. Zfp365 KO mice developed a significantly higher fibrotic response compared with WT mice by morphology and hydroxyproline content. Silencing ZNF365 in human lung fibroblasts and alveolar epithelial cells induced a significant reduction of growth rate and increased senescence markers, including Senescence Associated ß Galactosidase activity, p53, p21, and the histone variant γH2AX. Our findings demonstrate that ZNF365 is upregulated in IPF and experimental lung fibrosis and suggest a protective role since its absence increases experimental lung fibrosis mechanistically associated with the induction of cell senescence.

Evaluating of Red Blood Cell Distribution Width, Comorbidities and Electrocardiographic Ratios as Predictors of Prognosis in Patients with Pulmonary Hypertension.

Pulmonary hypertension is a rare condition that impairs patients' quality of life and life expectancy. The development of noninvasive instruments may help elucidate the prognosis of this cardiorespiratory disease. We aimed to evaluate the utility of routinely performed noninvasive test results as prognostic markers in patients with pulmonary hypertension. We enrolled 198 patients with mean pulmonary artery pressure >25 mmHg measured at cardiac catheterisation or echocardiographic pulmonary artery systolic pressure > 40 mmHg and tricuspid regurgitation Vmax >2.9 m/s, and clinical information regarding management and follow-up studies from the date of diagnosis. Multivariate analysis revealed that female sex [HR: 0.21, (95% CI: 0.07-0.64); p = 0.006], the presence of collagenopathies [HR: 8.63, (95% CI: 2.38-31.32); p = 0.001], an increased red blood cell distribution width [HR: 1.25, (95% CI: 1.04-1.49); p = 0.017] and an increased electrocardiographic P axis (P°)/T axis (T°) ratio [HR: 0.93, (95% CI: 0.88-0.98); p = 0.009] were severity-associated factors, while older age [HR: 1.57, (95% CI: 1.04-1.28); p = 0.006], an increased QRS axis (QRS°)/T° ratio [HR: 1.21, (95% CI: 1.09-1.34); p < 0.001], forced expiratory volume in 1 s [HR: 0.94, (95% CI: 0.91-0.98); p = 0.01] and haematocrit [HR: 0.93, (95% CI: 0.87-0.99); p = 0.04] were mortality-associated factors. Our results support the importance of red blood cell distribution width, electrocardiographic ratios and collagenopathies for assessing pulmonary hypertension prognosis.

Mitochondrial Dysfunction and Alterations in Mitochondrial Permeability Transition Pore (mPTP) Contribute to Apoptosis Resistance in Idiopathic Pulmonary Fibrosis Fibroblasts.

Idiopathic pulmonary fibrosis (IPF) is a devastating disease characterized by increased activation of fibroblasts/myofibroblasts. Previous reports have shown that IPF fibroblasts are resistant to apoptosis, but the mechanisms remain unclear. Since inhibition of the mitochondrial permeability transition pore (mPTP) has been implicated in the resistance to apoptosis, in this study, we analyzed the role of mitochondrial function and the mPTP on the apoptosis resistance of IPF fibroblasts under basal conditions and after mitomycin C-induced apoptosis. We measured the release of cytochrome c, mPTP opening, mitochondrial calcium release, oxygen consumption, mitochondrial membrane potential, ADP/ATP ratio, ATP concentration, and mitochondrial morphology. We found that IPF fibroblasts were resistant to mitomycin C-induced apoptosis and that calcium, a well-established activator of mPTP, is decreased as well as the release of pro-apoptotic proteins such as cytochrome c. Likewise, IPF fibroblasts showed decreased mitochondrial function, while mPTP was less sensitive to ionomycin-induced opening. Although IPF fibroblasts did not present changes in the mitochondrial membrane potential, we found a fragmented mitochondrial network with scarce, thinned, and disordered mitochondria with reduced ATP levels. Our findings demonstrate that IPF fibroblasts are resistant to mitomycin C-induced apoptosis and that altered mPTP opening contributes to this resistance. In addition, IPF fibroblasts show mitochondrial dysfunction evidenced by a decrease in respiratory parameters.

Hypoxia in Cancer and Fibrosis: Part of the Problem and Part of the Solution.

Adaptive responses to hypoxia are involved in the progression of lung cancer and pulmonary fibrosis. However, it has not been pointed out that hypoxia may be the link between these diseases. As tumors or scars expand, a lack of oxygen results in the activation of the hypoxia response, promoting cell survival even during chronic conditions. The role of hypoxia-inducible factors (HIFs) as master regulators of this adaptation is crucial in both lung cancer and idiopathic pulmonary fibrosis, which have shown the active transcriptional signature of this pathway. Emerging evidence suggests that interconnected feedback loops such as metabolic changes, fibroblast differentiation or extracellular matrix remodeling contribute to HIF overactivation, making it an irreversible phenomenon. This review will focus on the role of HIF signaling and its possible overlapping in order to identify new opportunities in therapy and regeneration.

Loss of MT1-MMP in Alveolar Epithelial Cells Exacerbates Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a lethal age-related lung disease whose pathogenesis involves an aberrant response of alveolar epithelial cells (AEC). Activated epithelial cells secrete mediators that participate in the activation of fibroblasts and the excessive deposition of extracellular matrix proteins. Previous studies indicate that matrix metalloproteinase 14 (MMP14) is increased in the lung epithelium in patients with IPF, however, the role of this membrane-type matrix metalloproteinase has not been elucidated. In this study, the role of Mmp14 was explored in experimental lung fibrosis induced with bleomycin in a conditional mouse model of lung epithelial MMP14-specific genetic deletion. Our results show that epithelial Mmp14 deficiency in mice increases the severity and extension of fibrotic injury and affects the resolution of the lesions. Gain-and loss-of-function experiments with human epithelial cell line A549 demonstrated that cells with a deficiency of MMP14 exhibited increased senescence-associated markers. Moreover, conditioned medium from these cells increased fibroblast expression of fibrotic molecules. These findings suggest a new anti-fibrotic mechanism of MMP14 associated with anti-senescent activity, and consequently, its absence results in impaired lung repair. Increased MMP14 in IPF may represent an anti-fibrotic mechanism that is overwhelmed by the strong profibrotic microenvironment that characterizes this disease.

Antitumor Therapy under Hypoxic Microenvironment by the Combination of 2-Methoxyestradiol and Sodium Dichloroacetate on Human Non-Small-Cell Lung Cancer.

A hypoxic microenvironment is a hallmark in different types of tumors; this phenomenon participates in a metabolic alteration that confers resistance to treatments. Because of this, it was proposed that a combination of 2-methoxyestradiol (2-ME) and sodium dichloroacetate (DCA) could reduce this alteration, preventing proliferation through the reactivation of aerobic metabolism in lung adenocarcinoma cell line (A549). A549 cells were cultured in a hypoxic chamber at 1% O2 for 72 hours to determine the effect of this combination on growth, migration, and expression of hypoxia-inducible factors (HIFs) by immunofluorescence. The effect in the metabolism was evaluated by the determination of glucose/glutamine consumption and the lactate/glutamate production. The treatment of 2-ME (10 µM) in combination with DCA (40 mM) under hypoxic conditions showed an inhibitory effect on growth and migration. Notably, this reduction could be attributed to 2-ME, while DCA had a predominant effect on metabolic activity. Moreover, this combination decreases the signaling of HIF-3α and partially HIF-1α but not HIF-2α. The results of this study highlight the antitumor activity of the combination of 2-ME 10 µl/DCA 40 mM, even in hypoxic conditions.

PulmonDB: a curated lung disease gene expression database.

Chronic Obstructive Pulmonary Disease (COPD) and Idiopathic Pulmonary Fibrosis (IPF) have contrasting clinical and pathological characteristics and interesting whole-genome transcriptomic profiles. However, data from public repositories are difficult to reprocess and reanalyze. Here, we present PulmonDB, a web-based database (http://pulmondb.liigh.unam.mx/) and R library that facilitates exploration of gene expression profiles for these diseases by integrating transcriptomic data and curated annotation from different sources. We demonstrated the value of this resource by presenting the expression of already well-known genes of COPD and IPF across multiple experiments and the results of two differential expression analyses in which we successfully identified differences and similarities. With this first version of PulmonDB, we create a new hypothesis and compare the two diseases from a transcriptomics perspective.

Dysregulated expression of hypoxia-inducible factors augments myofibroblasts differentiation in idiopathic pulmonary fibrosis.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is an age-related, progressive and lethal disease, whose pathogenesis is associated with fibroblasts/myofibroblasts foci that produce excessive extracellular matrix accumulation in lung parenchyma. Hypoxia has been described as a determinant factor in its development and progression. However, the role of distinct members of this pathway is not completely described. METHODS: By western blot, quantitative PCR, Immunohistochemistry and Immunocitochemistry were evaluated, the expression HIF alpha subunit isoforms 1, 2 & 3 as well, as their role in myofibroblast differentiation in lung tissue and fibroblast cell lines derived from IPF patients. RESULTS: Hypoxia signaling pathway was found very active in lungs and fibroblasts from IPF patients, as demonstrated by the abundance of alpha subunits 1 and 2, which further correlated with the increased expression of myofibroblast marker αSMA. In contrast, HIF-3α showed reduced expression associated with its promoter hypermethylation. CONCLUSIONS: This study lends further support to the involvement of hypoxia in the pathogenesis of IPF, and poses HIF-3α expression as a potential negative regulator of these phenomena.

Phosphatidylethanolamine Induces an Antifibrotic Phenotype in Normal Human Lung Fibroblasts and Ameliorates Bleomycin-Induced Lung Fibrosis in Mice.

Lung surfactant is a complex mixture of phospholipids and specific proteins but its role in the pathogenesis of interstitial lung diseases is not established. Herein, we analyzed the effects of three representative phospholipid components, that is, dipalmitoilphosphatidylcoline (DPPC), phosphatidylglycerol (PG) and phosphatidylethanolamine (PE), on collagen expression, apoptosis and Ca2+ signaling in normal human lung fibroblasts (NHLF) and probed their effect in an experimental model of lung fibrosis. Collagen expression was measured with RT-PCR, apoptosis was measured by using either the APOPercentage assay kit (Biocolor Ltd., Northern Ireland, UK) or the Caspase-Glo 3/7 assay (Promega, Madison, WI, USA) and Ca2+ signaling by conventional epifluorescence imaging. The effect in vivo was tested in bleomycin-induced lung fibrosis in mice. DPPC and PG did not affect collagen expression, which was downregulated by PE. Furthermore, PE promoted apoptosis and induced a dose-dependent Ca2+ signal. PE-induced Ca2+ signal and apoptosis were both blocked by phospholipase C, endoplasmic reticulum pump and store-operated Ca2+ entry inhibition. PE-induced decrease in collagen expression was attenuated by blocking phospholipase C. Finally, surfactant enriched with PE and PE itself attenuated bleomycin-induced lung fibrosis and decreased the soluble collagen concentration in mice lungs. This study demonstrates that PE strongly contributes to the surfactant-induced inhibition of collagen expression in NHLF through a Ca2+ signal and that early administration of Beractant enriched with PE diminishes lung fibrosis in vivo.

mTORC1 activation decreases autophagy in aging and idiopathic pulmonary fibrosis and contributes to apoptosis resistance in IPF fibroblasts.

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and usually lethal disease associated with aging. However, the molecular mechanisms of the aging process that contribute to the pathogenesis of IPF have not been elucidated. IPF is characterized by abundant foci of highly active fibroblasts and myofibroblasts resistant to apoptosis. Remarkably, the role of aging in the autophagy activity of lung fibroblasts and its relationship with apoptosis, as adaptive responses, has not been evaluated previously in this disease. In the present study, we analyzed the dynamics of autophagy in primary lung fibroblasts from IPF compared to young and age-matched normal lung fibroblasts. Our results showed that aging contributes for a lower induction of autophagy on basal conditions and under starvation which is mediated by mTOR pathway activation. Treatment with rapamycin and PP242, that target the PI3K/AKT/mTOR signaling pathway, modified starvation-induced autophagy and apoptosis in IPF fibroblasts. Interestingly, we found a persistent activation of this pathway under starvation that contributes to the apoptosis resistance in IPF fibroblasts. These findings indicate that aging affects adaptive responses to stress decreasing autophagy through activation of mTORC1 in lung fibroblasts. The activation of this pathway also contributes to the resistance to cell death in IPF lung fibroblasts.

Reviving Lonidamine and 6-Diazo-5-oxo-L-norleucine to Be Used in Combination for Metabolic Cancer Therapy.

Abnormal metabolism is another cancer hallmark. The two most characterized altered metabolic pathways are high rates of glycolysis and glutaminolysis, which are natural targets for cancer therapy. Currently, a number of newer compounds to block glycolysis and glutaminolysis are being developed; nevertheless, lonidamine and 6-diazo-5-oxo-L-norleucine (DON) are two old drugs well characterized as inhibitors of glycolysis and glutaminolysis, respectively, whose clinical development was abandoned years ago when the importance of cancer metabolism was not fully appreciated and clinical trial methodology was less developed. In this review, a PubMed search using the words lonidamine and 6-diazo-5-oxo-L-norleucine (DON) was undertaken to analyse existing information on the preclinical and clinical studies of these drugs for cancer treatment. Data show that they exhibit antitumor effects; besides there is also the suggestion that they are synergistic. We conclude that lonidamine and DON are safe and potentially effective drugs that need to be reevaluated in combination as metabolic therapy of cancer.

PINK1 deficiency impairs mitochondrial homeostasis and promotes lung fibrosis.

Although aging is a known risk factor for idiopathic pulmonary fibrosis (IPF), the pathogenic mechanisms that underlie the effects of advancing age remain largely unexplained. Some age-related neurodegenerative diseases have an etiology that is related to mitochondrial dysfunction. Here, we found that alveolar type II cells (AECIIs) in the lungs of IPF patients exhibit marked accumulation of dysmorphic and dysfunctional mitochondria. These mitochondrial abnormalities in AECIIs of IPF lungs were associated with upregulation of ER stress markers and were recapitulated in normal mice with advancing age in response to stimulation of ER stress. We found that impaired mitochondria in IPF and aging lungs were associated with low expression of PTEN-induced putative kinase 1 (PINK1). Knockdown of PINK1 expression in lung epithelial cells resulted in mitochondria depolarization and expression of profibrotic factors. Moreover, young PINK1-deficient mice developed similarly dysmorphic, dysfunctional mitochondria in the AECIIs and were vulnerable to apoptosis and development of lung fibrosis. Our data indicate that PINK1 deficiency results in swollen, dysfunctional mitochondria and defective mitophagy, and promotes fibrosis in the aging lung.

Matrix metalloproteinase (MMP)-19-deficient fibroblasts display a profibrotic phenotype.

Idiopathic pulmonary fibrosis (IPF) is a progressive and usually lethal interstitial lung disease of unknown etiology characterized by aberrant activation of epithelial cells that induce the migration, proliferation and activation of fibroblasts. The resulting distinctive fibroblastic/myofibroblastic foci are responsible for the excessive extracellular matrix (ECM) production and abnormal lung remodeling. We have recently found that matrix metalloproteinase 19 (MMP-19)-deficient (Mmp19-/-) mice develop an exaggerated bleomycin-induced lung fibrosis, but the mechanisms are unclear. In this study, we explored the effect of MMP-19 deficiency on fibroblast gene expression and cell behavior. Microarray analysis of Mmp19-/- lung fibroblasts revealed the dysregulation of several profibrotic pathways, including ECM formation, migration, proliferation, and autophagy. Functional studies confirmed these findings. Compared with wild-type mice, Mmp19-/- lung fibroblasts showed increased α1 (I) collagen gene and collagen protein production at baseline and after transforming growth factor-ß treatment and increased smooth muscle-α actin expression (P < 0.05). Likewise, Mmp19-deficient lung fibroblasts showed a significant increase in proliferation (P < 0.01) and in transmigration and locomotion over Boyden chambers coated with type I collagen or with Matrigel (P < 0.05). These findings suggest that, in lung fibroblasts, MMP-19 has strong regulatory effects on the synthesis of key ECM components, on fibroblast to myofibroblast differentiation, and in migration and proliferation.