PTX3 shapes profibrotic immune cells and epithelial/fibroblast repair and regeneration in a murine model of pulmonary fibrosis

The long pentraxin 3 (PTX3) is protective in different pathologies but was not analyzed in-depth in Idiopathic Pulmonary Fibrosis (IPF). Here, we have explored the influence of PTX3 in the bleomycin (BLM)-induced murine model of IPF by looking at immune cells (macrophages, mast cells, T cells) and stemness/regenerative markers of lung epithelium (SOX2) and fibro-blasts/myofibroblasts (CD44) at different time points that retrace the progression of the disease from onset at day 14, to full-blown disease at day 21, to incomplete regression at day 28. We took advantage of transgenic PTX3 overexpressing mice (Tie2-PTX3) and Ptx3 null ones (PTX3-KO) in which pulmonary fibrosis was induced. Our data have shown that PTX3 overexpression in Tie2-PTX3 compared to WT or PTX3-KO: reduced CD68+ and CD163+ macrophages and the Tryptase+ mast cells during the whole experimental time; on the contrary, CD4+ T cells are consistently present on day 14 and dramatically decreased on day 21; CD8+ T cells do not show significant differences on day 14, but are significantly reduced on day 21; SOX2 is reduced on days 14 and 21; CD44 is reduced on day 21. Therefore, PTX3 could act on the proimmune and fibrogenic microenvironment to prevent fibrosis in BLM-treated mice.

Usefulness of FAPα assessment in bronchoalveolar lavage as a marker of fibrogenesis: results of a preclinical study and first report in patients with idiopathic pulmonary fibrosis

BACKGROUND

Fibroblast activation protein-α (FAPα) is a marker of activated fibroblasts that can be selectively targeted by an inhibitor (FAPI) and visualised by PET/CT imaging. We evaluated whether the measurement of FAPα in bronchoalveolar lavage fluids (BALF) and the uptake of FAPI by PET/CT could be used as biomarkers of fibrogenesis.

METHODS

The dynamics of lung uptake of 18F-labeled FAPI ([18F]FAPI-74) was assessed in the bleomycin mouse model at various time points and using different concentrations of bleomycin by PET/CT. FAPα was measured in BALFs from these bleomycin-treated and control mice. FAPα levels were also assessed in BALFs from controls and patients with idiopathic pulmonary fibrosis (IPF).

RESULTS

Bleomycin-treated mice presented a significantly higher uptake of [18F]FAPI-74 during lung fibrinogenesis (days 10 and 16 after instillation) compared to control mice. No significant difference was observed at initial inflammatory phase (3 days) and when fibrosis was already established (28 days). [18F]FAPI-74 tracer was unable to show a dose-response to bleomycin treatment. On the other hand, BALF FAPα levels were steeply higher in bleomycin-treated mice at day 10 and a significant dose-response effect was observed. Moreover, FAPα levels were strongly correlated with lung fibrosis as measured by the modified Aschroft histological analysis, hydroxyproline and the percentage of weight loss. Importantly, higher levels of FAPα were observed in IPF patients where the disease was progressing as compared to stable patients and controls. Moreover, patients with FAPα BALF levels higher than 192.5 pg/mL presented a higher risk of progression, transplantation or death compared to patients with lower levels.

CONCLUSIONS

Our preclinical data highlight a specific increase of [18F]FAPI-74 lung uptake during the fibrotic phase of the bleomycin murine model. The measurement of FAPα in BALF appears to be a promising marker of the fibrotic activity in preclinical models of lung fibrosis and in IPF patients. Further studies are required to confirm the role of FAPα in BALF as biomarker of IPF activity and assess the relationship between FAPα levels in BALF and [18F]FAPI-74 uptake on PET/CT in patients with fibrotic lung disease.

Externalized histones fuel pulmonary fibrosis via a platelet-macrophage circuit of TGFβ1 and IL-27

Externalized histones erupt from the nucleus as extracellular traps, are associated with several acute and chronic lung disorders, but their implications in the molecular pathogenesis of interstitial lung disease are incompletely defined. To investigate the role and molecular mechanisms of externalized histones within the immunologic networks of pulmonary fibrosis, we studied externalized histones in human and animal bronchoalveolar lavage (BAL) samples of lung fibrosis. Neutralizing anti-histone antibodies were administered in bleomycin-induced fibrosis of C57BL/6 J mice, and subsequent studies used conditional/constitutive knockout mouse strains for TGFβ and IL-27 signaling along with isolated platelets and cultured macrophages. We found that externalized histones (citH3) were significantly (P < 0.01) increased in cell-free BAL fluids of patients with idiopathic pulmonary fibrosis (IPF; n = 29) as compared to healthy controls (n = 10). The pulmonary sources of externalized histones were Ly6G+CD11b+ neutrophils and nonhematopoietic cells after bleomycin in mice. Neutralizing monoclonal anti-histone H2A/H4 antibodies reduced the pulmonary collagen accumulation and hydroxyproline concentration. Histones activated platelets to release TGFβ1, which signaled through the TGFbRI/TGFbRII receptor complex on LysM+ cells to antagonize macrophage-derived IL-27 production. TGFβ1 evoked multiple downstream mechanisms in macrophages, including p38 MAPK, tristetraprolin, IL-10, and binding of SMAD3 to the IL-27 promotor regions. IL-27RA-deficient mice displayed more severe collagen depositions suggesting that intact IL-27 signaling limits fibrosis. In conclusion, externalized histones inactivate a safety switch of antifibrotic, macrophage-derived IL-27 by boosting platelet-derived TGFβ1. Externalized histones are accessible to neutralizing antibodies for improving the severity of experimental pulmonary fibrosis.

Low-level ambient sulfur dioxide exposure and genetic susceptibility associated with incidence of idiopathic pulmonary fibrosis: A national prospective cohort study

BACKGROUND

The association between long-term air pollution exposure and the development of idiopathic pulmonary fibrosis (IPF) has been established, but the evidence regarding the effect of low levels of air pollution, especially ambient sulfur dioxide (SO2), is limited. Besides, the combined effect and interaction between genetic susceptibility and ambient SO2 on IPF remain uncertain.

METHODS

This study retrieved data from 402,042 participants who were free of IPF at baseline in the UK Biobank. The annual mean concentration of ambient SO2 was estimated for each participant based on their residential addresses using a bilinear interpolation method. Cox proportional hazard models were used to examine the relationship between ambient SO2 and incident IPF. We further generated a polygenic risk score (PRS) for IPF and estimated the combined effects of genetic susceptibility and ambient SO2 on incident IPF.

RESULTS

After a median follow-up of 11.78 years, 2562 cases of IPF were identified. The results indicated that each 1 μg/m3 increase in ambient SO2 was associated with a hazard ratio (HR) (95% confidence interval [CI]) of 1.67 (1.58, 1.76) for incident IPF. The study found statistically significant synergistic additive interaction between genetic susceptibility and ambient SO2. Individuals with high genetic risk and high ambient SO2 exposure had a higher risk of developing IPF (HR = 7.48, 95% CI:5.66, 9.90).

CONCLUSION

The study suggests that long-term exposure to ambient SO2, even at concentrations lower than current air quality guidelines set by the Word Health Organization and European Union, may be an important risk factor for IPF. This risk is more pronounced among people with a high genetic risk. Therefore, these findings emphasize the need to consider the potential health effects of SO2 exposure and the necessity for stricter air quality standards.

End-Stage Idiopathic Pulmonary Fibrosis Lung Microenvironment Promotes Impaired NK Activity

Idiopathic pulmonary fibrosis (IPF) is a fibrotic age-related chronic lung disease characterized by the accumulation of senescent cells. Whether impaired immune response is responsible for the accumulation of senescent cells in the IPF lung remains unknown. In this study, we characterized the NK phenotype in IPF lungs via flow cytometry using 5-dodecanoylaminofluorescein di-β-d-galactopyranoside, markers of tissue residence, and chemokine receptors. The effect of the lung microenvironment was evaluated using lung fibroblast (LF) conditioned media (CM), and the bleomycin-induced pulmonary fibrosis mouse model was used to assess the in vivo relationship between NK cells and the accumulation of senescent cells. We found that NK cells from the lower lobe of IPF patients exhibited immune-senescent and impaired CD57-NKG2A+ phenotype. We also observed that culture of NK cells from healthy donors in CM from IPF lower lobe lung fibroblasts induced a senescent-like phenotype and impaired cytotoxic capacity. There is an impaired NK recruitment by LF, and NKs presented decreased migration toward their CM. In addition, NK cell-depleted mice treated with bleomycin showed increased collagen deposition and accumulation of different populations of senescent cells compared with controls. The IPF lung microenvironment induces a dysfunctional NK phenotype limiting the clearance of lung senescent cells and the resolution of lung fibrosis. We propose that impaired NK activity could be one of the mechanisms responsible for perpetuating the accumulation of senescent cells in IPF lungs.

Real life data on nintedanib safety: idiopathic pulmonary fibrosis versus systemic sclerosis-interstitial lung disease and strategies adopted to manage adverse effects

OBJECTIVE

Nintedanib (NIN) is an antifibrotic drug approved to slow the progression of idiopathic pulmonary fibrosis (IPF) and systemic sclerosis-related interstitial lung disease (SSc-ILD). NIN can frequently cause gastrointestinal adverse effects. We aimed to investigate the NIN safety profile in a real life setting, comparing IPF and SSc-ILD patients and evaluating the strategies adopted to manage NIN adverse effects.

METHODS

Patients taking NIN for IPF or SSc-ILD were enrolled. Alongside epidemiological and disease-specific data, the period of NIN use and the need for dosage reduction and/or interruption were investigated. Particular attention was paid to possible adverse effects and strategies adopted to manage them.

RESULTS

Twenty-seven SSc-ILD and 82 IPF patients were enrolled. No significant differences emerged between the two cohorts regarding the frequency of any possible adverse effect. Although the rates of NIN dosage reduction or interruption were similar between the two subgroups, SSc-ILD presented a mean period before NIN dosage reduction and NIN interruption significantly shorter than IPF (3 ± 2.6 vs 10.5 ± 8.9 months-p < 0.001 and 2.3 ± 0.5 vs 10.3 ± 9.9 months-p = 0.008, respectively). Several different strategies were tried to manage NIN adverse effects: especially in SSc-ILD, the variable combination of diet adjustment set by a nutritionist, probiotics and diosmectite was ultimately successful in maintaining patients on an adequate dose of NIN.

CONCLUSION

We presented data on the NIN safety profile in a real life setting, which was similar between SSc-ILD and IPF. A combination of multiple managing strategies and dose adjustment appears essential to cope optimally with NIN adverse effects.

SRC and TKS5 mediated podosome formation in fibroblasts promotes extracellular matrix invasion and pulmonary fibrosis

The activation and accumulation of lung fibroblasts resulting in aberrant deposition of extracellular matrix components, is a pathogenic hallmark of Idiopathic Pulmonary Fibrosis, a lethal and incurable disease. In this report, increased expression of TKS5, a scaffold protein essential for the formation of podosomes, was detected in the lung tissue of Idiopathic Pulmonary Fibrosis patients and bleomycin-treated mice. Τhe profibrotic milieu is found to induce TKS5 expression and the formation of prominent podosome rosettes in lung fibroblasts, that are retained ex vivo, culminating in increased extracellular matrix invasion. Tks5+/- mice are found resistant to bleomycin-induced pulmonary fibrosis, largely attributed to diminished podosome formation in fibroblasts and decreased extracellular matrix invasion. As computationally predicted, inhibition of src kinase is shown to potently attenuate podosome formation in lung fibroblasts and extracellular matrix invasion, and bleomycin-induced pulmonary fibrosis, suggesting pharmacological targeting of podosomes as a very promising therapeutic option in pulmonary fibrosis.

TGFβ1-RCN3-TGFBR1 loop facilitates pulmonary fibrosis by orchestrating fibroblast activation

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) bears high mortality due to unclear pathogenesis and limited therapeutic options. Therefore, identifying novel regulators is required to develop alternative therapeutic strategies.

METHODS

The lung fibroblasts from IPF patients and Reticulocalbin 3 (RCN3) fibroblast-selective knockdown mouse model were used to determine the importance of Rcn3 in IPF; the epigenetic analysis and protein interaction assays, including BioID, were used for mechanistic studies.

RESULTS

Reticulocalbin 3 (RCN3) upregulation is associated with the fibrotic activation of lung fibroblasts from IPF patients and Rcn3 overexpression blunts the antifibrotic effects of pirfenidone and nintedanib. Moreover, repressing Rcn3 expression in mouse fibroblasts ameliorates bleomycin-induced lung fibrosis and pulmonary dysfunction in vivo. Mechanistically, RCN3 promotes fibroblast activation by maintaining persistent activation of TGFβ1 signalling via the TGFβ1-RCN3-TGFBR1 positive feedback loop, in which RCN3 upregulated by TGFβ1 exposure detains EZH2 (an epigenetic methyltransferase) in the cytoplasm through RCN3-EZH2 interaction, leading to the release of the EZH2-H3K27me3 epigenetic repression of TGFBR1 and the persistent expression of TGFBR1.

CONCLUSIONS

These findings introduce a novel regulating mechanism of TGFβ1 signalling in fibroblasts and uncover a critical role of the RCN3-mediated loop in lung fibrosis. RCN3 upregulation may cause resistance to IPF treatment and targeting RCN3 could be a novel approach to ameliorate pulmonary fibrosis.

Asarinin attenuates bleomycin-induced pulmonary fibrosis by activating PPARγ

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive interstitial lung disease that lacks effective treatment modalities. Once patients are diagnosed with IPF, their median survival is approximately 3-5 years. PPARγ is an important target for the prevention and treatment of pulmonary fibrosis. Asarinin is a lignan compound that can be extracted from food plant Asarum heterotropoides. In this study, we investigated the therapeutic effects of asarinin in a pulmonary fibrosis model constructed using bleomycin in mice and explored the underlying mechanisms. Intraperitoneal administration of asarinin to mice with pulmonary fibrosis showed that asarinin effectively attenuated pulmonary fibrosis, and this effect was significantly inhibited by the PPARγ inhibitor GW9662. Asarinin inhibited TGF-β1-induced fibroblast-to-myofibroblast transition in vitro, while GW9662 and PPARγ gene silencing significantly inhibited this effect. In addition, asarinin inhibited not only the canonical Smad pathway of TGF-β but also the non-canonical AKT and MAPK pathways by activating PPARγ. Our study demonstrates that asarinin can be used as a therapeutic agent for pulmonary fibrosis, and that PPARγ is its key target.

Circ_PWWP2A promotes lung fibroblast proliferation and fibrosis via the miR-27b-3p/GATA3 axis, thereby aggravating idiopathic pulmonary fibrosis

OBJECTIVE

This paper was to investigate the effect of circ_PWWP2A-mediated miR-27b-3p/GATA3 axis on idiopathic pulmonary fibrosis (IPF).

METHODS

circ_PWWP2A expression in lung fibroblasts MLg2908 induced by different concentrations of TGF-β was detected. The relationship between circ_PWWP2A or GATA3 and miR-27b-3p was analyzed by RNA immunoprecipitation and dual-luciferin reporter assay. The proliferation of MLg2908 cells was determined by MTT. GATA3, α-SMA, Collagen-I, and Collagen-III in cells were detected by RT-qPCR and Western blot. The rat model of IPF induced by bleomycin (BLM) was constructed and treated with circ_PWWP2A siRNA injection. HE and Masson staining were of utility to evaluate the pathological conditions of rat lung tissue, and circ_PWWP2A, miR-27b-3p, and GATA3 levels in lung tissues were detected by RT-qPCR. Immunohistochemistry was used to detect the staining of α-SMA, collagen I, and collagen III in the lung tissues of rats.

RESULTS

circ_PWWP2A in MLg2908 cells induced by TGF-β decreased in a concentration-dependent manner. MLg2908 cells transfected with circ_PWWP2A siRNA were induced by 5 ng/ml TGF-β, decreasing circ_PWWP2A and GATA3 levels, increasing miR-27b-3p expression, and suppressing cell proliferation. The targeting relationship between circ_PWWP2A and miR-27b-3p, as well as miR-27b-3p and GATA3, was confirmed. Depleting miR-27b-3p reduced the inhibitory effect of circ_PWWP2A down-regulation on the proliferation of TGF-β-treated MLg2908 cells, accompanied by increased expression of α-SMA, Collagen 1, and Collagen 3, and increased expression of GATA3. The in vivo results showed that BLM-induced fibrosis in rat lung tissue was obvious, accompanied by increased expression of circ_PWWP2A and GATA3, decreased expression of miR-27b-3p, and deepened staining of α-SMA, collagen I, and collagen III, but circ_PWWP2A siRNA could improve these phenomena.

CONCLUSION

Silencing circ_PWWP2A can inhibit the proliferation of lung fibroblasts induced by TGF-β through the miR-27b-3p/GATA3 axis, and reduce BLM-induced pulmonary fibrosis in rats, which may be a potential therapeutic target for IPF.

Niclosamide-loaded nanoparticles (Ncl-NPs) reverse pulmonary fibrosis in vivo and in vitro

INTRODUCTION

Idiopathic pulmonary fibrosis (IPF), a life-threatening interstitial lung disease, is characterized by excessive activation and proliferation of fibroblasts and epithelial-mesenchymal transition (EMT) of alveolar epithelial cells (AEC) accompanied by a large amount of extracellular matrix aggregation. There are no therapies to reverse pulmonary fibrosis, and nintedanib and pirfenidone could only slow down the decline of lung function of IPF patients and delay their survival time. Niclosamide (Ncl) is an antihelminthic drug approved by FDA, which has been reported to have pleiotropic pharmacological activities in recent years, but it's almost complete insolubility in water limits its clinical application.

OBJECTIVES

To improve the water solubility of Ncl, explore its ability to reverse BLM-induced pulmonary fibrosis and its specific mechanism of action.

METHODS

The Niclosamide-loaded nanoparticles (Ncl-NPs) were formed by emulsification solvent evaporation method. A mouse model induced by bleomycin (BLM) was established to evaluate its effects and mechanisms of inhibiting and reversing fibrosis in vivo. The cell models treated by transforming growth factor-β1 (TGF-β1) were used to examine the mechanism of Ncl-NPs inhibiting fibrosis in vitro. Flow cytometry, IHC, IL-4-induced macrophage model and co-culture system were used to assess the effect of Ncl-NPs on M2 polarization of macrophages.

RESULTS

The Ncl-NPs improved the poor water solubility of Ncl. The lower dose of Ncl-NPs (2.5 mg/kg) showed the same effect of reversing established pulmonary fibrosis as free Ncl (5 mg/kg). Mechanistic studies revealed that Ncl-NPs blocked TGF-β/Smad and signaling transducer and activator of transcription 3 (Stat3) signaling pathways and inhibited the M2 polarization of macrophages. Additionally, H&E staining of the tissues initially showed the safety of Ncl-NPs.

CONCLUSION

These results indicate Ncl-NPs may serve as a new idea for the treatment of pulmonary fibrosis.

Time-course transcriptome analysis of a double challenge bleomycin-induced lung fibrosis rat model uncovers ECM homoeostasis-related translationally relevant genes

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is an irreversible disorder with a poor prognosis. The incomplete understanding of IPF pathogenesis and the lack of accurate animal models is limiting the development of effective treatments. Thus, the selection of clinically relevant animal models endowed with similarities with the human disease in terms of lung anatomy, cell biology, pathways involved and genetics is essential. The bleomycin (BLM) intratracheal murine model is the most commonly used preclinical assay to evaluate new potential therapies for IPF. Here, we present the findings derived from an integrated histomorphometric and transcriptomic analysis to investigate the development of lung fibrosis in a time-course study in a BLM rat model and to evaluate its translational value in relation to IPF.

METHODS

Rats were intratracheally injected with a double dose of BLM (days 0-4) and sacrificed at days 7, 14, 21, 28 and 56. Histomorphometric analysis of lung fibrosis was performed on left lung sections. Transcriptome profiling by RNAseq was performed on the right lung lobes and results were compared with nine independent human gene-expression IPF studies.

RESULTS

The histomorphometric and transcriptomic analyses provided a detailed overview in terms of temporal gene-expression regulation during the establishment and repair of the fibrotic lesions. Moreover, the transcriptomic analysis identified three clusters of differentially coregulated genes whose expression was modulated in a time-dependent manner in response to BLM. One of these clusters, centred on extracellular matrix (ECM)-related process, was significantly correlated with histological parameters and gene sets derived from human IPF studies.

CONCLUSIONS

The model of lung fibrosis presented in this study lends itself as a valuable tool for preclinical efficacy evaluation of new potential drug candidates. The main finding was the identification of a group of persistently dysregulated genes, mostly related to ECM homoeostasis, which are shared with human IPF.

Adipose-derived mesenchymal stem cell therapy for reverse bleomycin-induced experimental pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive respiratory disease. Arguably, the complex interplay between immune cell subsets, coupled with an incomplete understanding of disease pathophysiology, has hindered the development of successful therapies. Despite efforts to understand its pathophysiology and develop effective treatments, IPF remains a fatal disease, necessitating the exploration of new treatment options. Mesenchymal stromal/stem cell (MSC) therapy has shown promise in experimental models of IPF, but further investigation is needed to understand its therapeutic effect. This study aimed to assess the therapeutic effect of adipose-derived mesenchymal stem cells in a bleomycin-induced pulmonary fibrosis model. First, MSC cells were obtained from mice and characterized using flow cytometry and cell differentiation culture methods. Then adult C57BL/6 mice were exposed to endotracheal instillation of bleomycin and concurrently treated with MSCs for reversal models on day 14. Experimental groups were evaluated on days 14, 21, or 28. Additionally, lung fibroblasts challenged with TGF-β1 were treated with MSCs supernatant or MSCs to explore the mechanisms underlying of pulmonary fibrosis reversal. Mesenchymal stem cells were successfully isolated from mouse adipose tissue and characterized based on their differentiation ability and cell phenotype. The presence of MSCs or their supernatant stimulated the proliferation and migration of lung fibrotic cells. MSCs supernatant reduced lung collagen deposition, improved the Ashcroft score and reduced the gene and protein expression of lung fibrosis-related substances. Bleomycin-challenged mice exhibited severe septal thickening and prominent fibrosis, which was effectively reversed by MSCs treatment. MSC supernatant could suppress the TGF-β1/Smad signaling pathway and supernatant promotes fibroblast autophagy. In summary, this study demonstrates that MSCs supernatant treatment is as effective as MSCs in revert the core features of bleomycin-induced pulmonary fibrosis. The current study has demonstrated that MSCs supernatant alleviates the BLM-induced pulmonary fibrosis in vivo. In vitro experiments further reveal that MSC supernatant could suppress the TGF-β1/Smad signaling pathway to inhibit the TGF-β1-induced fibroblast activation, and promotes fibroblast autophagy by Regulating p62 expression. These findings contribute to the growing body of evidence supporting the therapeutic application of MSCs in cell therapy medicine for IPF.

Discovery of HDAC6, HDAC8, and 6/8 Inhibitors and Development of Cell-Based Drug Screening Models for the Treatment of TGF-β-Induced Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis is incurable, and its progression is difficult to control and thus can lead to pulmonary deterioration. Pan-histone deacetylase inhibitors such as SAHA have shown potential for modulating pulmonary fibrosis yet with off-target effects. Therefore, selective HDAC inhibitors would be beneficial for reducing side effects. Toward this goal, we designed and synthesized 24 novel HDAC6, HDAC8, or dual HDAC6/8 inhibitors and established a two-stage screening platform to rapidly screen for HDAC inhibitors that effectively mitigate TGF-β-induced pulmonary fibrosis. The first stage consisted of a mouse NIH-3T3 fibroblast prescreen and yielded five hits. In the second stage, human pulmonary fibroblasts (HPFs) were used, and four out of the five hits were tested for caco-2 permeability and liver microsome stability to give two potential leads: J27644 (15) and 20. This novel two-stage screen platform will accelerate the discovery and reduce the cost of developing HDAC inhibitors to mitigate TGF-β-induced pulmonary fibrosis.

Nalbuphine Tablets for Cough in Patients with Idiopathic Pulmonary Fibrosis

BACKGROUND: There are no approved therapies for cough in patients with idiopathic pulmonary fibrosis (IPF). In this small crossover trial we administered nalbuphine extended-release tablets (NAL ER) as a potential cough therapy for such patients. METHODS: This randomized, double-blind, placebo-controlled, crossover trial involved two 22-day treatment periods (NAL ER→placebo and placebo→NAL ER) separated by a 2-week washout period. NAL ER was started at a dose of 27 mg once daily and was titrated up to 162 mg twice daily at day 16. The primary end point was percent change from baseline in hourly daytime objective cough frequency as measured by an electronic cough monitor. The daytime period was defined as the patient-reported time of awakening and bedtime. Secondary end points included change in objective 24-hour cough frequency, changes in cough frequency, cough severity, and breathlessness, per patient-reported outcomes. RESULTS: A total of 41 patients were randomly assigned and received one or more doses of study medication. There was a 75.1% reduction in daytime objective cough frequency during the NAL ER treatment period versus the placebo treatment period of 22.6%, a 52.5 percentage point placebo-adjusted decrease from baseline (P<0.001) at day 21. There was a 76.1% (95% confidence interval, 83.1 to 69.1) decrease in the 24-hour objective cough frequency with NAL ER, versus a 25.3% (43.9 to 6.7) decrease with placebo, a 50.8 percentage point placebo-adjusted change. Nausea, fatigue, constipation, and dizziness were more common with NAL ER than with placebo. CONCLUSIONS: In this short-term crossover trial, NAL ER reduced cough in individuals with IPF. Larger and longer trials are needed to assess the impact on cough versus drug adverse effects. (Funded by Trevi Therapeutics; ClinicalTrials.gov number, NCT04030026.)

Pulmonary Fibrosis: Unveiling the Pathogenesis, Exploring Therapeutic Targets, and Advancements in Drug Delivery Strategies

Idiopathic pulmonary fibrosis (IPF) is an ailment with no cure and a very high rate of progression that ultimately leads to death. The exact reason for this disease is still not acknowledged. Many underlying mechanisms of wound healing and various types of stimuli that trigger the pathogenesis of IPF continue to be intensively explored. The exact therapy for the reversal of this disease is not yet known and is constantly in progress. Existing treatments only slow down the process or mitigate the symptoms to enhance the patient's healthcare system. The only two Food and Drug Administration-approved oral medications include pirfenidone and nintedanib whose high dose and systemic circulation can have side effects to a greater extent. Further research on restorative and extra-curative therapies for IPF is necessary due to the absence of viable therapeutic choices. To assure minimum off-targeted site delivery and longer duration of action, techniques that offer a sustainable release of the drug, better bioavailability, and patient compliance can be used.The work is an overview of the main therapeutic targets and pertinent developing therapies for the management of IPF. This study is an attempt to focus on various drug delivery systems that are responsible for showing effectiveness in defense mechanisms against IPF.

AAV9-Tspyl2 gene therapy retards bleomycin-induced pulmonary fibrosis by modulating downstream TGF-β signaling in mice

Idiopathic pulmonary fibrosis (IPF) is a devastating fibrotic lung disease characterized by scarring and destruction of the lung architecture, with limited treatment options. Targeted gene therapy to restore cell division autoantigen-1 (CDA1) expression may be a potential treatment approach to delay the progression of pulmonary fibrosis (PF). Here, we focused on CDA1, which was significantly decreased in human IPF, in a mouse model of bleomycin (BLM)-induced PF, and in transforming growth factor (TGF-β)-challenged lung fibroblasts. In vitro, CDA1 overexpression by lentivirus infection in human embryonic lung fibroblasts (HFL1 cells) inhibited the production of pro-fibrotic and pro-inflammatory cytokines, lung fibroblast-to-myofibroblast transition, and extracellular matrix protein expression induced by exogenous TGF-β1 treatment, whereas CDA1 knockdown with small interfering RNA promoted this effect. CDA1 overexpression also inhibited cell proliferation and migration. In a mouse model of BLM-induced PF, we provided novel evidence that the intratracheal delivery of adeno-associated virus serotype 9 carrying the mouse Tspyl2 gene reduced lung tissue inflammation and fibrosis. Mechanistically, CDA1, as a transcription regulator, could repress the TGF-β signal transduction in vivo and in vitro. In conclusion, our results show that Tspyl2 gene therapy plays an antifibrotic role by inhibiting the lung fibroblast-to-myofibroblast transition and downstream TGF-β/Smad3 signaling transduction in BLM-induced PF in mice, suggesting that CDA1 is an appropriate and promising therapeutic target for PF.

Inositol possesses antifibrotic activity and mitigates pulmonary fibrosis

BACKGROUND

Myo-inositol (or inositol) and its derivatives not only function as important metabolites for multiple cellular processes but also act as co-factors and second messengers in signaling pathways. Although inositol supplementation has been widely studied in various clinical trials, little is known about its effect on idiopathic pulmonary fibrosis (IPF). Recent studies have demonstrated that IPF lung fibroblasts display arginine dependency due to loss of argininosuccinate synthase 1 (ASS1). However, the metabolic mechanisms underlying ASS1 deficiency and its functional consequence in fibrogenic processes are yet to be elucidated.

METHODS

Metabolites extracted from primary lung fibroblasts with different ASS1 status were subjected to untargeted metabolomics analysis. An association of ASS1 deficiency with inositol and its signaling in lung fibroblasts was assessed using molecular biology assays. The therapeutic potential of inositol supplementation in fibroblast phenotypes and lung fibrosis was evaluated in cell-based studies and a bleomycin animal model, respectively.

RESULTS

Our metabolomics studies showed that ASS1-deficient lung fibroblasts derived from IPF patients had significantly altered inositol phosphate metabolism. We observed that decreased inositol-4-monophosphate abundance and increased inositol abundance were associated with ASS1 expression in fibroblasts. Furthermore, genetic knockdown of ASS1 expression in primary normal lung fibroblasts led to the activation of inositol-mediated signalosomes, including EGFR and PKC signaling. Treatment with inositol significantly downregulated ASS1 deficiency-mediated signaling pathways and reduced cell invasiveness in IPF lung fibroblasts. Notably, inositol supplementation also mitigated bleomycin-induced fibrotic lesions and collagen deposition in mice.

CONCLUSION

These findings taken together demonstrate a novel function of inositol in fibrometabolism and pulmonary fibrosis. Our study provides new evidence for the antifibrotic activity of this metabolite and suggests that inositol supplementation may be a promising therapeutic strategy for IPF.

Lung endothelial cells regulate pulmonary fibrosis through FOXF1/R-Ras signaling

Pulmonary fibrosis results from dysregulated lung repair and involves multiple cell types. The role of endothelial cells (EC) in lung fibrosis is poorly understood. Using single cell RNA-sequencing we identified endothelial transcription factors involved in lung fibrogenesis, including FOXF1, SMAD6, ETV6 and LEF1. Focusing on FOXF1, we found that FOXF1 is decreased in EC within human idiopathic pulmonary fibrosis (IPF) and mouse bleomycin-injured lungs. Endothelial-specific Foxf1 inhibition in mice increased collagen depositions, promoted lung inflammation, and impaired R-Ras signaling. In vitro, FOXF1-deficient EC increased proliferation, invasion and activation of human lung fibroblasts, and stimulated macrophage migration by secreting IL-6, TNFα, CCL2 and CXCL1. FOXF1 inhibited TNFα and CCL2 through direct transcriptional activation of Rras gene promoter. Transgenic overexpression or endothelial-specific nanoparticle delivery of Foxf1 cDNA decreased pulmonary fibrosis in bleomycin-injured mice. Nanoparticle delivery of FOXF1 cDNA can be considered for future therapies in IPF.

Loss of IGFBP2 mediates alveolar type 2 cell senescence and promotes lung fibrosis

Accumulation of senescent cells contributes to age-related diseases including idiopathic pulmonary fibrosis (IPF). Insulin-like growth factor binding proteins (IGFBPs) regulate many biological processes; however, the functional contributions of IGFBP2 in lung fibrosis remain largely unclear. Here, we report that intranasal delivery of recombinant IGFBP2 protects aged mice from weight loss and demonstrated antifibrotic effects after bleomycin lung injury. Notably, aged human-Igfbp2 transgenic mice reveal reduced senescence and senescent-associated secretory phenotype factors in alveolar epithelial type 2 (AEC2) cells and they ameliorated bleomycin-induced lung fibrosis. Finally, we demonstrate that IGFBP2 expression is significantly suppressed in AEC2 cells isolated from fibrotic lung regions of patients with IPF and/or pulmonary hypertension compared with patients with hypersensitivity pneumonitis and/or chronic obstructive pulmonary disease. Altogether, our study provides insights into how IGFBP2 regulates AEC2-cell-specific senescence and that restoring IGFBP2 levels in fibrotic lungs can prove effective for patients with IPF.

Mirtazepine, an atypical antidepressant, mitigates lung fibrosis by suppressing NLPR3 inflammasome and fibrosis-related mediators in endotracheal bleomycin rat model

Idiopathic pulmonary fibrosis (IPF) is a progressive and irreversible lung disease with a poor prognosis. There is currently no definitive cure for IPF. The present study establishes a platform for the development of a novel therapeutic approach for the treatment of PF using the atypical antidepressant, mirtazapine. In the endotracheal bleomycin rat model, mirtazapine interfered with the activation of NLRP3 inflammasome via downregulating the NLRP3 on the gene and protein expression levels. Accordingly, the downstream mediators IL-1β and IL-18 were repressed. Such observation is potentially a direct result of the reported improvement in oxidative stress. Additionally, mirtazapine corrected the bleomycin-induced disparities in the levels of the fibrogenic mediators TGF-β, PDGF-BB, and TIMP-1, in consequence, the lung content of hydroxyproline and the expression of α-SMA were reduced. Besides, mirtazapine curbed the ICAM-1 and the chemotactic cytokines MCP-1 and CXCL4. This protective property of mirtazapine resulted in improving the BALF total and differential cell counts, diminishing LDH activity, and reducing the BALF total protein. Moreover, the inflammation and fibrosis scores were accordingly lower. To conclude, we reveal for the first time the efficacy of mirtazapine as a potential treatment for PF. The combination of social isolation, sleep problems, breathing difficulties, and fear of death can lead to psychological distress and depression in patients with IPF. Hence, mirtazapine is a promising treatment option that may improve the prognosis for IPF patients due to its antifibrotic effects, as well as its ability to alleviate depressive episodes.

LncRNA GAS5 suppresses TGF-β1-induced transformation of pulmonary pericytes into myofibroblasts by recruiting KDM5B and promoting H3K4me2/3 demethylation of the PDGFRα/β promoter

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a condition that may cause persistent pulmonary damage. The transformation of pericytes into myofibroblasts has been recognized as a key player during IPF progression. This study aimed to investigate the functions of lncRNA growth arrest-specific transcript 5 (GAS5) in myofibroblast transformation during IPF progression.

METHODS

We created a mouse model of pulmonary fibrosis (PF) via intratracheal administration of bleomycin. Pericytes were challenged with exogenous transforming growth factor-β1 (TGF-β1). To determine the expression of target molecules, we employed quantitative reverse transcription-polymerase chain reaction, Western blotting, and immunohistochemical and immunofluorescence staining. The pathological changes in the lungs were evaluated via H&E and Masson staining. Furthermore, the subcellular distribution of GAS5 was examined using FISH. Dual-luciferase reporter assay, ChIP, RNA pull-down, and RIP experiments were conducted to determine the molecular interaction.

RESULTS

GAS5 expression decreased whereas PDGFRα/β expression increased in the lungs of IPF patients and mice with bleomycin-induced PF. The in vitro overexpression of GAS5 or silencing of PDGFRα/β inhibited the TGF-β1-induced differentiation of pericytes to myofibroblasts, as evidenced by the upregulation of pericyte markers NG2 and desmin as well as downregulation of myofibroblast markers α-SMA and collagen I. Further mechanistic analysis revealed that GAS5 recruited KDM5B to promote H3K4me2/3 demethylation, thereby suppressing PDGFRα/β expression. In addition, KDM5B overexpression inhibited pericyte-myofibroblast transformation and counteracted the promotional effect of GAS5 knockdown on pericyte-myofibroblast transformation. Lung fibrosis in mice was attenuated by GAS5 overexpression but promoted by GAS5 deficiency.

CONCLUSION

GAS5 represses pericyte-myofibroblast transformation by inhibiting PDGFRα/β expression via KDM5B-mediated H3K4me2/3 demethylation in IPF, identifying GAS5 as an intervention target for IPF.

Transforming Growth Factor-β1 Regulates Peroxisomal Genes/Proteins via Smad Signaling in Idiopathic Pulmonary Fibrosis Fibroblasts and Transgenic Mouse Models

Idiopathic pulmonary fibrosis (IPF) is a chronic human disease with persistent destruction of lung parenchyma. Transforming growth factor-β1 (TGF-β1) signaling plays a pivotal role in the initiation and pathogenesis of IPF. As shown herein, TGF-β1 signaling down-regulated not only peroxisome biogenesis but also the metabolism of these organelles in human IPF fibroblasts. In vitro cell culture observations in human fibroblasts and human lung tissue indicated that peroxisomal biogenesis and metabolic proteins were significantly down-regulated in the lung of 1-month-old transgenic mice expressing a constitutively active TGF-β type I receptor kinase (ALK5). The peroxisome biogenesis protein peroxisomal membrane protein Pex13p (PEX13p) as well as the peroxisomal lipid metabolic enzyme peroxisomal acyl-coenzyme A oxidase 1 (ACOX1) and antioxidative enzyme catalase were highly up-regulated in TGF-β type II receptor and Smad3 knockout mice. This study reports a novel mechanism of peroxisome biogenesis and metabolic regulation via TGF-β1-Smad signaling: interaction of the Smad3 transcription factor with the PEX13 gene in chromatin immunoprecipitation-on-chip assay as well as in a bleomycin-induced pulmonary fibrosis model applied to TGF-β type II receptor knockout mice. Taken together, data from this study suggest that TGF-β1 participates in regulation of peroxisomal biogenesis and metabolism via Smad-dependent signaling, opening up novel strategies for the development of therapeutic approaches to inhibit progression of pulmonary fibrosis patients with IPF.

Small-molecule-mediated OGG1 inhibition attenuates pulmonary inflammation and lung fibrosis in a murine lung fibrosis model

Interstitial lung diseases such as idiopathic pulmonary fibrosis (IPF) are caused by persistent micro-injuries to alveolar epithelial tissues accompanied by aberrant repair processes. IPF is currently treated with pirfenidone and nintedanib, compounds which slow the rate of disease progression but fail to target underlying pathophysiological mechanisms. The DNA repair protein 8-oxoguanine DNA glycosylase-1 (OGG1) has significant roles in the modulation of inflammation and metabolic syndromes. Currently, no pharmaceutical solutions targeting OGG1 have been utilized in the treatment of IPF. In this study we show Ogg1-targeting siRNA mitigates bleomycin-induced pulmonary fibrosis in male mice, highlighting OGG1 as a tractable target in lung fibrosis. The small molecule OGG1 inhibitor, TH5487, decreases myofibroblast transition and associated pro-fibrotic gene expressions in fibroblast cells. In addition, TH5487 decreases levels of pro-inflammatory mediators, inflammatory cell infiltration, and lung remodeling in a murine model of bleomycin-induced pulmonary fibrosis conducted in male C57BL6/J mice. OGG1 and SMAD7 interact to induce fibroblast proliferation and differentiation and display roles in fibrotic murine and IPF patient lung tissue. Taken together, these data suggest that TH5487 is a potentially clinically relevant treatment for IPF but further study in human trials is required.

PM2.5 and constituent component impacts on global DNA methylation in patients with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive interstitial lung disease (ILD) whose outcomes are worsened with air pollution exposures. DNA methylation (DNAm) patterns are altered in lungs and blood from patients with IPF, but the relationship between air pollution exposures and DNAm patterns in IPF remains unexplored. This study aimed to evaluate the association of PM_2.5 and constituent components with global DNAm in patients with IPF. Patients enrolled in either the University of Pittsburgh Simmons Center for ILD Registry (Simmons) or the U.S.-wide Pulmonary Fibrosis Foundation (PFF) Patient Registry with peripheral blood DNA samples were included. The averages of monthly exposures to PM_2.5 and constituents over 1-year and 3-months pre-blood collection were matched to patient residential coordinates using satellite-derived hybrid models. Global DNAm percentage (%5 mC) was determined using the ELISA-based MethylFlash assay. Associations of pollutants with %5 mC were assessed using beta-regression, Cox models for mortality, and linear regression for baseline lung function. Mediation proportion was determined for models where pollutant-mortality and pollutant-%5 mC associations were significant. Inclusion criteria were met by 313 Simmons and 746 PFF patients with IPF. Higher PM_2.5 3-month exposures prior to blood collection were associated with higher %5 mC in Simmons (β = 0.02, 95%CI 0.0003-0.05, p = 0.047), with trends in the same direction in the 1-year period in both cohorts. Higher exposures to sulfate, nitrate, ammonium, and black carbon constituents were associated with higher %5 mC in multiple models. Percent 5 mC was not associated with IPF mortality or lung function, but was found to mediate between 2 and 5% of the associations of PM_2.5, sulfate, and ammonium with mortality. In conclusion, we found that higher global DNAm is a novel biomarker for increased PM_2.5 and anthropogenic constituent exposure in patients with IPF. Mechanistic research is needed to determine if DNAm has pathogenic relevance in mediating associations between pollutants and mortality in IPF.