Murine Model Of Pulmonary Fibrosis Research Articles

The Long Noncoding RNA DNM3OS Is a Reservoir of FibromiRs with Major Functions in Lung Fibroblast Response to TGF-β and Pulmonary Fibrosis.

Rationale: Given the paucity of effective treatments for idiopathic pulmonary fibrosis (IPF), new insights into the deleterious mechanisms controlling lung fibroblast activation, the key cell type driving the fibrogenic process, are essential to develop new therapeutic strategies. TGF-β (transforming growth factor-β) is the main profibrotic factor, but its inhibition is associated with severe side effects because of its pleiotropic role. Objectives: To determine if downstream noncoding effectors of TGF-β in fibroblasts may represent new effective therapeutic targets whose modulation may be well tolerated. Methods: We investigated the whole noncoding fraction of TGF-β-stimulated lung fibroblast transcriptome to identify new genomic determinants of lung fibroblast differentiation into myofibroblasts. Differential expression of the long noncoding RNA (lncRNA) DNM3OS (dynamin 3 opposite strand) and its associated microRNAs (miRNAs) was validated in a murine model of pulmonary fibrosis and in IPF tissue samples. Distinct and complementary antisense oligonucleotide-based strategies aiming at interfering with DNM3OS were used to elucidate the role of DNM3OS and its associated miRNAs in IPF pathogenesis. Measurements and Main Results: We identified DNM3OS as a fibroblast-specific critical downstream effector of TGF-β-induced lung myofibroblast activation. Mechanistically, DNM3OS regulates this process in trans by giving rise to three distinct profibrotic mature miRNAs (i.e., miR-199a-5p/3p and miR-214-3p), which influence SMAD and non-SMAD components of TGF-β signaling in a multifaceted way. In vivo, we showed that interfering with DNM3OS function not only prevents lung fibrosis but also improves established pulmonary fibrosis. Conclusions: Pharmacological approaches aiming at interfering with the lncRNA DNM3OS may represent new effective therapeutic strategies in IPF.

Lung Microbiota Contribute to Pulmonary Inflammation and Disease Progression in Pulmonary Fibrosis.

Rationale: Idiopathic pulmonary fibrosis (IPF) causes considerable global morbidity and mortality, and its mechanisms of disease progression are poorly understood. Recent observational studies have reported associations between lung dysbiosis, mortality, and altered host defense gene expression, supporting a role for lung microbiota in IPF. However, the causal significance of altered lung microbiota in disease progression is undetermined. Objectives: To examine the effect of microbiota on local alveolar inflammation and disease progression using both animal models and human subjects with IPF. Methods: For human studies, we characterized lung microbiota in BAL fluid from 68 patients with IPF. For animal modeling, we used a murine model of pulmonary fibrosis in conventional and germ-free mice. Lung bacteria were characterized using 16S rRNA gene sequencing with novel techniques optimized for low-biomass sample load. Microbiota were correlated with alveolar inflammation, measures of pulmonary fibrosis, and disease progression. Measurements and Main Results: Disruption of the lung microbiome predicts disease progression, correlates with local host inflammation, and participates in disease progression. In patients with IPF, lung bacterial burden predicts fibrosis progression, and microbiota diversity and composition correlate with increased alveolar profibrotic cytokines. In murine models of fibrosis, lung dysbiosis precedes peak lung injury and is persistent. In germ-free animals, the absence of a microbiome protects against mortality. Conclusions: Our results demonstrate that lung microbiota contribute to the progression of IPF. We provide biological plausibility for the hypothesis that lung dysbiosis promotes alveolar inflammation and aberrant repair. Manipulation of lung microbiota may represent a novel target for the treatment of IPF.

Absence of early metabolic response assessed by 18F-FDG PET/CT after initiation of antifibrotic drugs in IPF patients

BackgroundIdiopathic pulmonary fibrosis (IPF) is characterized by a progressive and irreversible respiratory failure. Non-invasive markers of disease activity are essential for prognosis and evaluation of early response to anti-fibrotic treatments.ObjectivesThe aims of this study were to determine whether fluorodeoxyglucose ([18F]-FDG) lung uptake is reduced after initiation of pirfenidone or nintedanib and to assess its possible use as a prognostic factor.Methods[18F]-FDG PET/CT was performed in IPF patients and in a murine model of pulmonary fibrosis. PET/CTs were performed at day 8 and day 15 post-instillation of bleomycin in pirfenidone- or vehicule-treated mice. In IPF patients, PET-CT was performed before and 3 months after the initiation of pirfenidone or nintedanib.ResultsIn bleomycin-treated mice, pirfenidone significantly reduced the [18F]-FDG uptake compared to vehicule-treated mice at day 15 (p < 0.001), whereas no difference was observed at day 8 after bleomycin administration. In IPF patients, [18F]-FDG lung uptake before and after 3 months of treatment by nintedanib (n = 11) or pirfenidone (n = 14) showed no significant difference regardless the antifibrotic treatment. Moreover, no difference was noticed between patients with progressive or non-progressive disease at one year of follow up.ConclusionsPirfenidone significantly reduces the lung [18F]-FDG uptake during the fibrotic phase in a mouse model of IPF. However, these preclinical data were not confirmed in IPF patients 3 months after the initiation of antifibrotic therapy. [18F]-FDG seems therefore not useful in clinical practice to assess the early response of IPF patients to nintedanib or pirfenidone.

Study of the effects of nintedanib ethanesulfonate on bleomycin-induced murine pulmonary fibrosis model

Idiopathic pulmonary fibrosis (IPF) is a refractory disease that progresses from alveolar damage and inflammation to interstitial fibrosis. In this study, we confirmed the progress of the pathological condition of pulmonary fibrosis model in mice and investigated the effects of IPF therapeutic agent nintedanib ethanesulfonate (ofev).

Ionizing Radiation Promotes Epithelial-to-Mesenchymal Transition in Lung Epithelial Cells by TGF-β-producing M2 Macrophages.

Ionizing radiation induces pulmonary fibrosis, which is a common dose-limiting complication in patients receiving radiotherapy. Fibrosis occurs through the accumulation of large amounts of ECM components, synthesized by myofibroblasts in damaged lung tissue. Epithelial cells serve as one of the cellular sources of myofibroblasts via the epithelial-to-mesenchymal transition (EMT) process. In this study, we investigated the role of TGF-β-secreting M2 macrophages in association with ionizing radiation-induced EMT. The lung epithelial cell line MLE12, was irradiated and the expression of EMT markers and chemokines was examined. Moreover, the mouse lung macrophage MH-S cell line was cultured with conditioned media from irradiated MLE12 cells, to examine the effects of the secreted factors on the migration ability of macrophages. For the murine pulmonary fibrosis model, mice were locally irradiated and the levels of M1 or M2 macrophage-related markers and cytokines were measured in bronchoalvelolar lavage (BAL) fluid and lung tissue. In MLE12 cells, irradiation directly induced expression of EMT-related markers and secretion of various chemokines, which lead to macrophage migration. Interestingly, the sub-population of macrophages recruited in the lung of mice after thoracic irradiation was M2 macrophages that expressed Arg-1 and CD206. M2 macrophages induced the MLE12 to undergo phenotypic conversion to form fibroblast-like cells, which leads to a down-regulation of epithelial markers and an up-regulation of new EMT-related markers. In thoracic irradiated mice, pro-inflammatory cytokines such as IL-1β, IL-4 and IL-10 were increased at 2 weeks, but returned to normal levels from 16 weeks or 24 weeks after irradiation. However, thoracic irradiation led to a rapid increase of TGF-β and IGF-1 levels, which lasted up to 24 weeks. It was confirmed that M2 macrophages secreted the high levels of TGF-β. Moreover, the elimination of TGF-β from M2 macrophages attenuated mesenchymal transition of MLE12. TGF-β-secreting M2 macrophages play an important regulatory role in mesenchymal transition of epithelial cells in the lung of irradiated mice, thus contributing to radiation-induced pulmonary fibrosis.

Tetraspanin 1 inhibits TNFα-induced apoptosis via NF-κB signaling pathway in alveolar epithelial cells.

Tetraspanin family plays an important role in the pathogenesis of cancer, but its role in lung fibrosis is unknown. To determine whether tetraspanin 1 (TSPAN1), a member of the family, may be involved in the pathogenesis of pulmonary fibrosis. TNFα -stimulated human alveolar epithelial (A549) and alveolar epithelial type II cell (AT2) were treated in vitro. Murine pulmonary fibrosis model was generated by injection of bleomycin (BLM). The expression of TSPAN1 was examined in vivo using the bleomycin-induced lung fibrosis model and tissue sample of IPF patients. Then we transfected the cells with TSPAN1 siRNA or plasmid and detected the expression changes of related proteins and cell apoptosis. In our study, we found that TSPAN1 was markedly down-regulated in lung tissue of patients with idiopathic pulmonary fibrosis (IPF) and in bleomycin-induced pulmonary fibrosis in mice. We also found that TSPAN1 was significantly down-regulated in A549 and primary (AT2) cells following exposure to TNFα. Meanwhile, TSPAN1 inhibited p-IκBα, which attenuated nuclear NF-κB translocation and activation and inhibited apoptosis. We demonstrated that TSPAN1 reduced Bax translocation and caspase-3 activation, inhibited the apoptosis by regulating the NF-κB pathway in response to TNFα. We conclude that TSPAN1 mediated apoptosis resistance of alveolar epithelial cells by regulating the NF-κB pathway. TSPAN1 may be a potential therapeutic target for pulmonary fibrosis or acute lung injury.

PD-1 up-regulation on CD4+ T cells promotes pulmonary fibrosis through STAT3-mediated IL-17A and TGF-β1 production.

Pulmonary fibrosis is a progressive inflammatory disease with high mortality and limited therapeutic options. Previous genetic and immunologic investigations suggest common intersections between idiopathic pulmonary fibrosis (IPF), sarcoidosis, and murine models of pulmonary fibrosis. To identify immune responses that precede collagen deposition, we conducted molecular, immunohistochemical, and flow cytometric analysis of human and murine specimens. Immunohistochemistry revealed programmed cell death-1 (PD-1) up-regulation on IPF lymphocytes. PD-1+CD4+ T cells with reduced proliferative capacity and increased transforming growth factor-β (TGF-β)/interleukin-17A (IL-17A) expression were detected in IPF, sarcoidosis, and bleomycin CD4+ T cells. PD-1+ T helper 17 cells are the predominant CD4+ T cell subset expressing TGF-β. Coculture of PD-1+CD4+ T cells with human lung fibroblasts induced collagen-1 production. Strikingly, ex vivo PD-1 pathway blockade resulted in reductions in TGF-β and IL-17A expression from CD4+ T cells, with concomitant declines in collagen-1 production from fibroblasts. Molecular analysis demonstrated PD-1 regulation of the transcription factor STAT3 (signal transducer and activator of transcription 3). Chemical blockade of STAT3, using the inhibitor STATTIC, inhibited collagen-1 production. Both bleomycin administration to PD-1 null mice or use of antibody against programmed cell death ligand 1 (PD-L1) demonstrated significantly reduced fibrosis compared to controls. This work identifies a critical, previously unrecognized role for PD-1+CD4+ T cells in pulmonary fibrosis, supporting the use of readily available therapeutics that directly address interstitial lung disease pathophysiology.

Dasatinib Suppresses TGFβ-Mediated Epithelial-Mesenchymal Transition in Alveolar Epithelial Cells and Inhibits Pulmonary Fibrosis.

Transforming growth factor β (TGFβ)-mediated epithelial-mesenchymal transition (EMT) of alveolar epithelial cells contributes to pulmonary fibrosis. Dasatinib (DAS), a potent and broad-spectrum tyrosine kinase inhibitor, has been widely studied as an anti-cancer agent. However, the therapeutic application of DAS for pulmonary fibrosis has not been clarified. Our purpose here is to investigate the effect of DAS on TGFβ1-induced EMT in human alveolar and bronchial epithelial cells in vitro and to evaluate the efficacy of DAS on lung fibrosis in vivo. TGFβ1-stimulated human alveolar epithelial (A549) and bronchial epithelial (BEAS-2B) cells were treated with or without DAS in vitro. Murine pulmonary fibrosis model was generated by injection of bleomycin (BLM). A549 and BEAS-2B cells exposed to TGFβ1 underwent EMT, as indicated by downregulation of epithelial protein E-cadherin and induction of the mesenchymal proteins, fibronectin and type I and type IV collagen. These effects were dramatically suppressed by DAS treatment, which also prevented Smad2 and Smad3 phosphorylation. DAS inhibited TGFβ1-induced cell motility and migration. Furthermore, DAS administration significantly attenuated lung fibrosis in mice by histological analysis. Treatment with DAS also significantly reduced the levels of collagen and fibronectin and phosphorylation of Smad2 in the lung tissues of the murine model. These findings suggest that DAS inhibited TGFβ-mediated EMT of alveolar and bronchial epithelial cells and attenuated BLM-induced lung fibrosis in mice by suppressing the TGFβ/Smad pathway. DAS may be a promising and novel anti-fibrotic agent for preventing lung fibrosis.

Olodaterol shows anti-fibrotic efficacy in in vitro and in vivo models of pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a fatal respiratory disease characterized by excessive fibroblast activation ultimately leading to scarring of the lungs. Although, the activation of β2 -adrenoceptors (β2 -AR) has been shown to inhibit pro-fibrotic events primarily in cell lines, the role of β2 -adrenoceptor agonists has not yet been fully characterized. The aim of our study was to explore the anti-fibrotic activity of the long-acting β2 -adrenoceptor agonist olodaterol in primary human lung fibroblasts (HLF) and in murine models of pulmonary fibrosis. We assessed the activity of olodaterol to inhibit various pro-fibrotic mechanisms, induced by different pro-fibrotic mediators, in primary HLF from control donors and patients with IPF (IPF-LF). The in vivo anti-fibrotic activity of olodaterol, given once daily by inhalation in either a preventive or therapeutic treatment regimen, was explored in murine models of lung fibrosis induced by either bleomycin or the overexpression of TGF-β1. In both HLF and IPF-LF, olodaterol attenuated TGF-β-induced expression of α-smooth muscle actin, fibronectin and endothelin-1 (ET-1), FGF- and PDGF-induced motility and proliferation and TGF-β/ET-1-induced contraction. In vivo olodaterol significantly attenuated the bleomycin-induced increase in lung weight, reduced bronchoalveolar lavage cell counts and inhibited release of pro-fibrotic mediators (TGF-ß, MMP-9 and tissue inhibitor of metalloproteinase-1). Forced vital capacity was increased only with the preventive treatment regimen. In the TGF-β-overexpressing model, olodaterol additionally reduced the Col3A1 mRNA expression. Olodaterol showed anti-fibrotic properties in primary HLF from control and IPF patients and in murine models of lung fibrosis.

Reduced expression of BMP3 contributes to the development of pulmonary fibrosis and predicts the unfavorable prognosis in IIP patients.

Idiopathic pulmonary fibrosis (IPF) and idiopathic nonspecific interstitial pneumonia (INSIP) are two related diseases involving varying degrees of pulmonary fibrosis with no effective cure. Bone morphogenetic protein 3 (BMP3) is a member of the transforming growth factor-β (TGF-β) super-family, which has not been implicated in pulmonary fibrosis previously. In this study, we aimed to investigate the potential role of BMP3 playing in pulmonary fibrosis from clinical diagnosis to molecular signaling regulation. RNA sequencing was performed to explore the potential biomarker of IIP patients. The expression of BMP3 was evaluated in 83 cases of IPF and INSIP by immunohistochemistry. The function of BMP3 was investigated in both fibroblast cells and a bleomycin-induced murine pulmonary fibrosis model. The clinical relevance of BMP3 expression were analyzed in 47 IIP patients, which were included in 83 cases and possess more than five-year follow-up data. Both RNA-sequencing and immunohistochemistry staining revealed that BMP3 was significantly down-regulated in lung tissues of patients with IPF and INSIP. Consistently, lower expression of BMP3 also was found in pulmonary fibrotic tissues of bleomycin-induced mice model. Up-regulation of BMP3 prevented pulmonary fibrosis processing through inhibiting cellular proliferation of fibroblasts as well as TGF-β1 signal transduction. Finally, the relatively higher expression of BMP3 in IPF patients was associated with less/worse mortality. Intravenous injection of recombinant BMP3. Taken together, our results suggested that the low expression level of BMP3 may indicate the unfavorable prognosis of IPF patients, targeting BMP3 may represent a novel potential therapeutic method for pulmonary fibrosis management.

Effects of the fibroblast activation protein inhibitor, PT100, in a murine model of pulmonary fibrosis

Bleomycin (BLM) induced lung injury is detectable in C57BL/6 mice using magnetic resonance imaging (MRI). We investigated the effects of the fibroblast activation protein (FAP) inhibitor, PT100, in this model. BLM (0.5mg/kg/day) was administered on days −7, −6, −5, −2, −1, 0 in the nostrils of male mice. PT100 (40µg/mouse) or vehicle (0.9%NaCl) was dosed per os twice daily from day 1–14. MRI was performed before BLM and at days 0, 7 and 14. After the last MRI acquisition, animals were euthanised and the lungs harvested for histological and quantitative real-time polymerase chain reaction (qRT-PCR) analyses. As evidenced longitudinally by MRI, the BLM-elicited lesions in the lungs of vehicle-treated mice progressed over time. In contrast, responses elicited by BLM did not progress in animals receiving PT100. Histology demonstrated significant less fibrosis in PT100- than in vehicle-treated, BLM-challenged mice. Significant correlation (R=0.91, P<0.001, N=24) was found between the volumes of BLM-induced lesions detected in vivo by MRI and the collagen content determined histologically (picrosirius staining). FAP was overexpressed in the lungs of BLM-challenged mice. Upon PT100 treatment, FAP expression was reduced. Significant differences in the MMP-12, MIP-1α, and MCP-3 mRNA expression levels in the lungs of PT100- compared to vehicle-treated mice were also revealed by qRT-PCR. The IBA-1 level determined histologically was higher in the lungs of PT100- compared to vehicle-treated mice. Taken together, these observations suggest that treatment with PT100 in this murine model of pulmonary fibrosis had an anti-fibro-proliferative effect and increased macrophage activation.

X-ray dark-field radiography facilitates the diagnosis of pulmonary fibrosis in a mouse model

The aim of this study was to evaluate whether diagnosing pulmonary fibrosis with projection radiography can be improved by using X-ray dark-field radiograms. Pulmonary X-ray transmission and dark-field images of C57Bl/6N mice, either treated with bleomycin to induce pulmonary fibrosis or PBS to serve as controls, were acquired with a prototype grating-based small-animal scanner. Two blinded readers, both experienced radiologists and familiar with dark-field imaging, had to assess dark-field and transmission images for the absence or presence of fibrosis. Furthermore readers were asked to grade their stage of diagnostic confidence. Histological evaluation of the lungs served as the standard of reference in this study. Both readers showed a notably higher diagnostic confidence when analyzing the dark-field radiographs (p < 0.001). Diagnostic accuracy improved significantly when evaluating the lungs in dark-field images alone (p = 0.02) or in combination with transmission images (p = 0.01) compared to sole analysis of absorption images. Interreader agreement improved from good when assessing only transmission images to excellent when analyzing dark-field images alone or in combination with transmission images. Adding dark-field images to conventional transmission images in a murine model of pulmonary fibrosis leads to an improved diagnosis of this disease on chest radiographs.

BRD4 mediates NF-κB-dependent epithelial-mesenchymal transition and pulmonary fibrosis via transcriptional elongation.

Chronic epithelial injury triggers a TGF-β-mediated cellular transition from normal epithelium into a mesenchymal-like state that produces subepithelial fibrosis and airway remodeling. Here we examined how TGF-β induces the mesenchymal cell state and determined its mechanism. We observed that TGF-β stimulation activates an inflammatory gene program controlled by the NF-κB/RelA signaling pathway. In the mesenchymal state, NF-κB-dependent immediate-early genes accumulate euchromatin marks and processive RNA polymerase. This program of immediate-early genes is activated by enhanced expression, nuclear translocation, and activating phosphorylation of the NF-κB/RelA transcription factor on Ser276, mediated by a paracrine signal. Phospho-Ser276 RelA binds to the BRD4/CDK9 transcriptional elongation complex, activating the paused RNA Pol II by phosphorylation on Ser2 in its carboxy-terminal domain. RelA-initiated transcriptional elongation is required for expression of the core epithelial-mesenchymal transition transcriptional regulators SNAI1, TWIST1, and ZEB1 and mesenchymal genes. Finally, we observed that pharmacological inhibition of BRD4 can attenuate experimental lung fibrosis induced by repetitive TGF-β challenge in a mouse model. These data provide a detailed mechanism for how activated NF-κB and BRD4 control epithelial-mesenchymal transition initiation and transcriptional elongation in model airway epithelial cells in vitro and in a murine pulmonary fibrosis model in vivo. Our data validate BRD4 as an in vivo target for the treatment of pulmonary fibrosis associated with inflammation-coupled remodeling in chronic lung diseases.

Sirtuin 3 Deregulation Promotes Pulmonary Fibrosis.

Oxidative stress leads to alveolar epithelial cell injury and fibroblast-myofibroblast differentiation (FMD), key events in the pathobiology of pulmonary fibrosis (PF). Sirtuin 3 (SIRT3) is a mitochondrial protein deacetylase regulator of antioxidant response and mitochondrial homeostasis. Here, we demonstrate reduced SIRT3 expression in the lungs of old mice compared to young mice, as well as in two murine models of PF. The analysis of the pattern of SIRT3 expression in the lungs of patients with PF revealed low SIRT3 staining within the fibrotic regions. We also demonstrated, using murine models of PF and human lung fibroblasts, that reduced SIRT3 expression in response to transforming growth factor beta 1 (TGFβ1) promotes acetylation (inactivation) of major oxidative stress response regulators, such as SOD2 and isocitrate dehydrogenase 2. Reduction of SIRT3 in human lung fibroblasts promoted FMD. By contrast, overexpression of SIRT3 attenuated TGFβ1-mediated FMD and significantly reduced the levels of SMAD family member 3 (SMAD3). Resveratrol induced SIRT3 expression and ameliorated acetylation changes induced by TGFβ1. We demonstrated that SIRT3-deficient mice are more susceptible to PF compared to control mice, and concomitantly exhibit enhanced SMAD3 expression. Collectively, these data define a SIRT3/TGFβ1 interaction during aging that may play a significant role in the pathobiology of PF.

CD4+CD25hiFoxp3+ Cells Exacerbate Bleomycin-Induced Pulmonary Fibrosis

Idiopathic pulmonary fibrosis is a fatal lung disease with a median survival of 2 to 5 years. A decade of studies has downplayed inflammation contributing to its pathogenesis. However, these studies preceded the discovery of regulatory T cells (Tregs) and all of their functions. On the basis of human studies demonstrating Tregs can decrease graft-versus-host disease and vasculitides, there is consideration of their use to treat idiopathic pulmonary fibrosis. We hypothesized that Treg therapy would attenuate the fibroplasia involved in a preclinical murine model of pulmonary fibrosis. IL-2 complex was used invivo to expand CD4(+)CD25(hi)Foxp3(+) cells in the lung during intratracheal bleomycin challenge; however, this unexpectedly led to an increase in lung fibrosis. More important, this increase in fibrosis was a lymphocyte-dependent process. We corroborated these results using a CD4(+)CD25(hi)Foxp3(+) cellular-based therapy. Mechanistically, we demonstrated that CD4(+)CD25(hi)Foxp3(+) cells undergo alterations during bleomycin challenge and the IL-2 complex had no effect on profibrotic (eg, transforming growth factor-β) or type 17 immune response cytokines; however, there was a marked down-regulation of the type 1 and augmentation of the type 2 immune response cytokines from the lungs. Collectively, our animal studies show that a specific lung injury can induce Treg alterations, which can augment pulmonary fibrosis.

182. Effects of Inflammation-Mediated Autophagy of Human Placental Mesenchymal Stem Cells of Fetal Origin on Their Immunomodulatory Properties and Therapeutic Potential in Bleomycin-Induced Pulmonary Fibrosis Models

Pulmonary fibrosis (PF) is an interstitial pulmonary disease caused by lung injury and inflammatory response, which is currently incurable in clinical settings. Fibroblast proliferation and extracellular matrix accumulation are the main clinical manifestation and pathogenic features of PF. An compelling number of evidence has demonstrated that mesenchymal stem cells (MSCs) pose therapeutic potentials in PF disease, owing to their strongly immunomodulatory roles in injury repair of tissues, including the lung. In this regards, the autophagy of MSCs induced by inflammatory microenvironment of pulmonary injury plays a critical role in their immunomodulatory properties. Our works have recently revealed that human placental MSCs of fetal origin (fPMSCs) have an ability to alleviate and reverse the pathological progress in a bleomycin-induced PF model. In order to better understand mechanisms underpinning the therapeutic effect of fPMSCs in pulmonary fibrosis, the inflammation-mediated MSC autophagy in murine pulmonary fibrosis model was interrogated. Our results demonstrated that the inflammatory microenvironment of PF was able to induce MSC autophagy in vitro and in vivo, implying that the inflammatory microenvironment of PF may trigger autophagy of fPMSCs, which in turn affects their therapeutic potentials to PF. These results also suggest that an interaction between autophagy of fPMSCs and PF inflammatory microenvironment may have a fundamental impact on immunomodulatory functions and therapeutic effects of fPMSCs on pulmonary. Key words: placenta; mesenchymal stem cells; cell therapy; pulmonary fibrosis; autophagy.

Non-invasive Imaging of Idiopathic Pulmonary Fibrosis Using Cathepsin Protease Probes.

Idiopathic pulmonary fibrosis (IPF) is a lethal, chronic, progressive disease characterized by formation of scar tissue within the lungs. Because it is a disease of unknown etiology, it is difficult to diagnose, to predict disease course and to devise treatment strategies. Recent evidence suggests that activated macrophages play key roles in the pathology of IPF. Therefore, imaging probes that specifically recognize these pools of activated immune cells could provide valuable information about how these cells contribute to the pathobiology of the disease. Here we demonstrate that cysteine cathepsin-targeted imaging probes can be used to monitor the contribution of macrophages to fibrotic disease progression in the bleomycin-induced murine model of pulmonary fibrosis. Furthermore, we show that the probes highlight regions of macrophage involvement in fibrosis in human biopsy tissues from IPF patients. Finally, we present first-in-human results demonstrating non-invasive imaging of active cathepsins in fibrotic lesions of patients with IPF. Together, our findings validate small molecule cysteine cathepsin probes for clinical PET imaging and suggest that they have the potential to be used to generate mechanistically-informative molecular information regarding cellular drivers of IPF disease severity and progression.

Establishment of a mouse model for pulmonary inflammation and fibrosis by intratracheal instillation of polyhexamethyleneguanidine phosphate.

Although several animal models have been developed to study human pulmonary fibrosis, lack of a perfect model has raised the need for various animal models of pulmonary fibrosis. In this study, we evaluated the pulmonary effect of polyhexamethyleneguanidine phosphate instillation into the lungs of mice to determine the potential of these mice as a murine model of pulmonary fibrosis. Intratracheal instillation of polyhexamethyleneguanidine phosphate induced severe lung inflammation manifested by the infiltration of mononuclear cells and neutrophils and increased production of IL-6, TNF-α, CCL2 and CXCL1. The lung inflammation gradually increased until 28 days after polyhexamethyleneguanidine phosphate exposure, and increases of collagen deposition and TGF-β production, which are indicators of pulmonary fibrosis, were seen. Our study showed that intratracheal instillation of polyhexamethyleneguanidine phosphate induces pulmonary inflammation and fibrosis in mice.

Effect and mechanism of inhibition of lipopolysaccharide-induced pulmonary fibrosis by butyric acid

To evaluate the inhibitory effect of butyric acid (BA) as a histone deacetylase (HDAC) inhibitor on lipopolysaccharide (LPS)-induced pulmonary fibrosis and its mechanism. Thirty C57/BL6 mice were randomly divided into three groups according to the random number method, namely control group (physiological saline was given intraperitoneally and by gavage), LPS challenge group (LPS-induced murine model of pulmonary fibrosis was reproduced with intraperitoneal injection of 10 mg/kg LPS), and BA preconditioning + LPS challenge group (10 mg/kg BA was given followed by intraperitoneal injection of 10 mg/kg LPS), with 10 mice in each group. Mice were sacrificed painlessly, and lung tissue samples were harvested at 2 weeks and 4 weeks respectively (five samples every group each time). HDAC activity was evaluated with fluorescence analysis kit. Protein expression of acetylated-histone H3 (Ace-H3), acetylated-histone H4 (Ace-H4) and thymocyte differentiation antigen 1 (Thy-1) were determined by Western Blot. The mRNA expression of Thy-1 was assessed by real-time reverse transcription- polymerase chain reaction (real-time RT-PCR). The degree of lung inflammation and fibrosis were microscopic detected after hematoxylin-eosin (HE) staining and Masson collagen staining. The deposition of lung collagen was detected by hydroxyproline content measurement kit. Compared to control group, the degree of lung inflammation and fibrosis was aggravated after LPS challenge, as manifested by increased hydroxyproline content (μg/mg, 2 weeks: 8.384±0.632 vs. 4.388±0.334, 4 weeks: 8.308±0.244 vs. 4.370±0.342, both P < 0.01), increased HDAC activity (μmol/L, 2 weeks: 7.243±0.384 vs. 3.628±0.641, 4 weeks: 6.479±0.202 vs. 3.238±0.524, both P < 0.01), increased deacetylation degree of histone H3 and H4 [relative expression of Ace-H3 (gray value): 0.516±0.115 vs. 1.005±0.359 at 2 weeks, 0.633±0.143 vs. 1.092±0.193 at 4 weeks, both P < 0.05; relative expression of Ace-H4 (gray value): 0.402±0.164 vs. 0.759±0.187 at 2 weeks, P > 0.05; 0.426±0.098 vs. 0.858±0.177 at 4 weeks, P < 0.01], and lowered Thy-1 mRNA and protein expression [Thy-1 mRNA (2(-ΔΔCt)): 0.606±0.066 vs. 1.005±0.109 at 2 weeks, P < 0.01; 0.824±0.101 vs. 1.210±0.400 at 4 weeks, P > 0.05; relative expression of Thy-1 protein (gray value): 0.725±0.284 vs. 1.249±0.297 at 2 weeks, 0.589±0.139 vs. 1.372±0.343 at 4 weeks, both P < 0.05]. Compared with LPS group, BA precondition could inhibit above processes, as manifested by decreased hydroxyproline content (μg/mg: 5.943±0.726 vs. 8.384±0.632 at 2 weeks, 4.938±0.209 vs. 8.308±0.244 at 4 weeks, both P < 0.01), decreased HDAC activity (μmol/L: 4.386±0.117 vs. 7.243±0.384 at 2 weeks, 4.863±0.096 vs. 6.479±0.202 at 4 weeks, both P < 0.01), increased Thy-1 mRNA expression at 2 weeks (2(-ΔΔCt): 0.884±0.216 vs. 0.606±0.066, P < 0.05), increased acetylation degree of histone H4 and Thy-1 protein expression at 4 weeks [relative expression of Ace-H4 (gray value): 0.715±0.145 vs. 0.426±0.098, P < 0.05; relative protein expression of Thy-1 (gray value): 0.939±0.098 vs. 0.589±0.139, P < 0.01]. LPS-induced pulmonary fibrosis was related with activation of HDAC, deacetylation of histone H3 and H4 and Thy-1 gene silencing. HDAC inhibitor BA could inhibit LPS-induced pulmonary fibrosis and Thy-1 gene silencing through inhibiting activation of HDAC and deacetylation of histone H4.

M10, a caspase cleavage product of the hepatocyte growth factor receptor, interacts with Smad2 and demonstrates antifibrotic properties in vitro and in vivo

Hepatocyte growth factor receptor, also known as cellular mesenchymal-epithelial transition factor (c-MET, MET), is an important antifibrotic molecule that protects various tissues, including lung, from injury and fibrosis. The intracellular cytoplasmic tail of MET contains a caspase-3 recognition motif "DEVD-T" that on cleavage by caspase-3 generates a 10-amino acid peptide, TRPASFWETS, designated as "M10". M10 contains at its N-terminus the uncharged amino acid proline (P) directly after a cationic amino acid arginine (R) which favors the transport of the peptide through membranes. M10, when added to cell culture medium, remains in the cytoplasm and nuclei of cells for up to 24 hours. M10 effectively decreases collagen in both scleroderma and TGFβ-stimulated normal lung and skin fibroblasts. M10 interacts with the Mad Homology 2 domain of Smad2 and inhibits TGFβ-induced Smad2 phosphorylation, suggesting that the antifibrotic effects of M10 are mediated in part by counteracting Smad-dependent fibrogenic pathways. In the bleomycin murine model of pulmonary fibrosis, M10 noticeably reduced lung inflammation and fibrosis. Ashcroft fibrosis scores and lung collagen content were significantly lower in bleomycin-treated mice receiving M10 as compared with bleomycin-treated mice receiving scrambled peptide. We conclude that M10 peptide interacts with Smad2 and demonstrates strong antifibrotic effects in vitro and in vivo in an animal model of lung fibrosis and should be considered as a potential therapeutic agent for systemic sclerosis and other fibrosing diseases.