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BackgroundWe recently demonstrated that the triple combination CFTR modulator therapy elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) improves lung ventilation and airway mucus plugging determined by multiple-breath washout and magnetic resonance imaging in CF patients with at least oneF508delallele. However, effects of ELX/TEZ/IVA on viscoelastic properties of airway mucus, chronic airway infection and inflammation have not been studied. The aim of this study was, therefore, to determine the effects of ELX/TEZ/IVA on airway mucus rheology, microbiome and inflammation in CF patients with one or twoF508delalleles aged 12 years and older.MethodsIn this prospective observational study, we assessed sputum rheology, the microbiome, inflammation markers and proteome before and 8 to 16 weeks after initiation of ELX/TEZ/IVA.ResultsIn total, 59 patients with CF and at least oneF508delallele and 10 healthy controls were enrolled in this study. ELX/TEZ/IVA improved the elastic modulus (G’; -6.3 Pa; IQR, -17.9 to 1.2;PPPPseudomonas aeruginosain CF sputum. ELX/TEZ/IVA also reduced IL-8 (−11.7 ng/ml, IQR, -36.5 to 11.2;PPConclusionsOur data demonstrate that ELX/TEZ/IVA improves sputum viscoelastic properties, chronic airway infection and inflammation in CF patients with at least oneF508delallele, however, without reaching levels close to healthy.Clinical trial registered withwww.clinicaltrials.gov(NCT04732910)

BackgroundMucin disulfide cross-links mediate pathologic mucus formation in muco-obstructive lung diseases. MUC-031, a novel thiol-modified carbohydrate compound, cleaves disulfides to cause mucolysis. The aim of this study was to determine the mucolytic and therapeutic effects of MUC-031 in sputum from patients with cystic fibrosis (CF) and mice with muco-obstructive lung disease (βENaC-Tg mice).MethodsWe compared the mucolytic efficacy of MUC-031 and existing mucolytics (N-acetylcysteine (NAC) and recombinant human deoxyribonuclease I (rhDNase)) using rheology to measure the elastic modulus (G′) of CF sputum, and we tested effects of MUC-031 on airway mucus plugging, inflammation and survival in βENaC-Tg mice to determine its mucolytic efficacyin vivo.ResultsIn CF sputum, compared to the effects of rhDNase and NAC, MUC-031 caused a larger decrease in sputum G′, was faster in decreasing sputum G′ by 50% and caused mucolysis of a larger proportion of sputum samples within 15 min of drug addition. Compared to vehicle control, three treatments with MUC-031 in 1 day in adult βENaC-Tg mice decreased airway mucus content (16.8±3.2versus7.5±1.2 nL·mm−2, pversus47 679±7736 cells·mL−1, pConclusionMUC-031 is a potent and fast-acting mucolytic that decreases airway mucus plugging, lessens airway inflammation and improves survival in βENaC-Tg mice. These data provide rationale for human trials of MUC-031 in muco-obstructive lung diseases.

Adult hepatic progenitor cells (HPCs)/oval cells are bipotential progenitors that participate in liver repair responses upon chronic injury. Recent findings highlight HPCs plasticity and importance of the HPCs niche signals to determine their fate during the regenerative process, favoring either fibrogenesis or damage resolution. Transforming growth factor-β (TGF-β) and hepatocyte growth factor (HGF) are among the key signals involved in liver regeneration and as component of HPCs niche regulates HPCs biology. Here, we characterize the TGF-β-triggered epithelial–mesenchymal transition (EMT) response in oval cells, its effects on cell fate in vivo, and the regulatory effect of the HGF/c-Met signaling. Our data show that chronic treatment with TGF-β triggers a partial EMT in oval cells based on coexpression of epithelial and mesenchymal markers. The phenotypic and functional profiling indicates that TGF-β-induced EMT is not associated with stemness but rather represents a step forward along hepatic lineage. This phenotypic transition confers advantageous traits to HPCs including survival, migratory/invasive and metabolic benefit, overall enhancing the regenerative potential of oval cells upon transplantation into a carbon tetrachloride-damaged liver. We further uncover a key contribution of the HGF/c-Met pathway to modulate the TGF-β-mediated EMT response. It allows oval cells expansion after EMT by controlling oxidative stress and apoptosis, likely via Twist regulation, and it counterbalances EMT by maintaining epithelial properties. Our work provides evidence that a coordinated and balanced action of TGF-β and HGF are critical for achievement of the optimal regenerative potential of HPCs, opening new therapeutic perspectives. Stem Cells 2019;37:1108–1118

The Histone Deacetylase 6 (HDAC6) enzyme has two deacetylase domains and is found almost exclusively in the cytoplasm. It deacetylates targets such as tubulin, cortactin, HSP90, KU70 and potentially the Treg-specific transcription factor FOXP3 but not histones under physiological conditions. COPD frequent exacerbators (COPD-FE) data suggest increased activity of HDAC6 and preclinical literature suggests HDAC6 inhibition/depletion rescues cilia shortening, mucociliary clearance defects and pulmonary barrier integrity, thus reducing susceptibility to acute lung injury. Additional literature describes functions in PAH, CF and IPF as well as non-pulmonary indications, with protection from various inflammatory diseases. Here we present the characterization of HDAC6 inhibitors in primary human bronchial epithelial cells grown at the air-liquid interface and Hdac6 KO mice in two preclinical models of COPD (elastase/LPS and cigarette smoke). HDAC6 inhibition and deficiency reduce mucus production and persistence of inflammation both in mice and in 3D human respiratory epithelia, with strong evidence for reducing MUC5AC positive cells as well as Mmp9 expression and neutrophilic inflammation. Thus, HDAC6 represents a solid pharmacological target with the potential to benefit COPD-FE patients, especially if suffering from chronic mucus hypersecretion. Method: H. Meier, F. Kolling, J. Auburger, L. Schneider, C. Noack, L. Dietz, D. Urrego, S. Schroder, I. Hagelschuer, T. Kramer

During chronic liver disease, hepatic progenitor cells (HPC, oval cells in rodents) become activated, proliferate, and differentiate into cholangiocytes and/or hepatocytes contributing to the final outcome of the regenerative process in a context-dependent fashion. Here, we analyze the crosstalk between the hepatocyte growth factor (HGF)/c-Met signaling axis, key for liver regeneration, and bone morphogenetic protein (BMP)9, a BMP family ligand that has emerged as a critical regulator of liver pathology. Our results show that HGF/c-Met signaling blocks BMP9-mediated apoptotic cell death, while it potentiates small mothers against decapentaplegic (SMAD)1 signaling triggered by BMP9 in oval cells. Interestingly, HGF-induced overactivation of SMAD1, -5, -8 requires the upregulation of TGF-&beta, type receptor activin receptor-like kinase (ALK)1, and both ALK1 and SMAD1 are required for the counteracting effect of HGF on BMP9 apoptotic activity. On the other hand, we also prove that BMP9 triggers the activation of p38MAPK in oval cells, which drives BMP9-apoptotic cell death. Therefore, our data support a model in which BMP9 and HGF/c-Met signaling axes establish a signaling crosstalk via ALK1 that modulates the balance between the two pathways with opposing activities, SMAD1 (pro-survival) and p38 mitogen-activated protein kinases (p38MAPK, pro-apoptotic), which determines oval cell fate. These data help delineate the complex signaling network established during chronic liver injury and its impact on the oval cell regenerative response.

[Objectives]: Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in Western countries. Protein tyrosine phosphatase 1B (PTP1B), a negative modulator of insulin and cytokine signaling, is a therapeutic target for type 2 diabetes and obesity. We investigated the impact of PTP1B deficiency during NAFLD, particularly in non-alcoholic steatohepatitis (NASH). [Methods]: NASH features were evaluated in livers from wild-type (PTP1BWT) and PTP1B-deficient (PTP1BKO) mice fed methionine/choline-deficient diet (MCD) for 8 weeks. A recovery model was established by replacing MCD to chow diet (CHD) for 2–7 days. Non-parenchymal liver cells (NPCs) were analyzed by flow cytometry. Oval cells markers were measured in human and mouse livers with NASH, and in oval cells from PTP1BWT and PTP1BKO mice. [Results]: PTP1BWT mice fed MCD for 8 weeks exhibited NASH, NPCs infiltration, and elevated Fgf21, Il6 and Il1b mRNAs. These parameters decreased after switching to CHD. PTP1B deficiency accelerated MCD-induced NASH. Conversely, after switching to CHD, PTP1BKO mice rapidly reverted NASH compared to PTP1BWT mice in parallel to the normalization of serum triglycerides (TG) levels. Among NPCs, a drop in cytotoxic natural killer T (NKT) subpopulation was detected in PTP1BKO livers during recovery, and in these conditions M2 macrophage markers were up-regulated. Oval cells markers (EpCAM and cytokeratin 19) significantly increased during NASH only in PTP1B-deficient livers. HGF-mediated signaling and proliferative capacity were enhanced in PTP1BKO oval cells. In NASH patients, oval cells markers were also elevated. [Conclusions]: PTP1B elicits a dual role in NASH progression and reversion. Additionally, our results support a new role for PTP1B in oval cell proliferation during NAFLD., This work was funded by SAF2015-65267-R (MINECO/FEDER), CIBERdem (ISCIII, Spain), INFLAMES (ISCIII PIE14/00045, co-funded by ERDF, “Investing in your future”) to A.M.V; IJCI-2014-19381 (MINECO/FEDER) to P.R and A.M.V; CP14/00181 and PI16/00823 (ISCIII/FEDER) and CIBERehd (ISCIII, Spain) to A.G-R; BFU2015-65937-R (MINECO/FEDER), 67-2015 (Department of Health, Navarra Government) and CIBERobn (ISCIII, Spain) to M.J.M; SAF2015-69145-R (MINECO/FEDER) to A.S. A.A. was recipient of a Marie Curie ESR contract from IT-LIVER (Marie Curie Action of the FP7-2012, grant agreement 316549). We also acknowledge the European Union, project H2020-MSCA-ITN TREATMENT Grant Agreement number: 721236.

The mucus layer is a hydrogel network that covers mucosal surfaces of the human body. Mucus has important protective properties that are related to its unique rheological properties, which are based on mucins being the main glycoprotein constituents. Mucin macromolecules entangle with one another and form a physical network that is instrumental for many important defense functions. Mucus derived from various human or animal sources is poorly defined and thus not suitable for many application purposes. Herein, a synthetic route is fabricated to afford a library of compositionally defined mucus-inspired hydrogels (MIHs). MIHs are synthesized by thiol oxidation to render disulfide bonds between the crosslinker ethoxylated trimethylolpropane tri(3-mercaptopropionate) (THIOCURE ETTMP 1300) and the linear precursors, dithiolated linear polyglycerol (LPG(SH)2 ) or polyethylene glycol (PEG(SH)2 ) of different molecular weights. The mixing ratio of linear polymers versus crosslinker and the length of the linear polymer are varied, thus delivering a library of compositionally defined mucin-inspired constructs. Their viscoelastic properties are determined by frequency sweeps at 25 and 37 °C and compared to the corresponding behavior of native human mucus. Here, MIHs composed of a 10:1 ratio of LPG(SH)2 and ETTMP 1300 are proved to be the best comparable to human airway mucus rheology.

Objective Bone morphogenetic protein (BMP)-9, a member of the transforming growth factor-β family of cytokines, is constitutively produced in the liver. Systemic levels act on many organs and tissues including bone and endothelium, but little is known about its hepatic functions in health and disease. Design Levels of BMP-9 and its receptors were analysed in primary liver cells. Direct effects of BMP-9 on hepatic stellate cells (HSCs) and hepatocytes were studied in vitro, and the role of BMP-9 was examined in acute and chronic liver injury models in mice. Results Quiescent and activated HSCs were identified as major BMP-9 producing liver cell type. BMP-9 stimulation of cultured hepatocytes inhibited proliferation, epithelial to mesenchymal transition and preserved expression of important metabolic enzymes such as cytochrome P450. Acute liver injury caused by partial hepatectomy or single injections of carbon tetrachloride (CCl 4 ) or lipopolysaccharide (LPS) into mice resulted in transient downregulation of hepatic BMP-9 mRNA expression. Correspondingly, LPS stimulation led to downregulation of BMP-9 expression in cultured HSCs. Application of BMP-9 after partial hepatectomy significantly enhanced liver damage and disturbed the proliferative response. Chronic liver damage in BMP-9-deficient mice or in mice adenovirally overexpressing the selective BMP-9 antagonist activin-like kinase 1-Fc resulted in reduced deposition of collagen and subsequent fibrosis. Conclusions Constitutive expression of low levels of BMP-9 stabilises hepatocyte function in the healthy liver. Upon HSC activation, endogenous BMP-9 levels increase in vitro and in vivo and high levels of BMP-9 cause enhanced damage upon acute or chronic injury.

Background & Aims: Upon ligand binding, tyrosine kinase receptors, such as epidermal growth factor receptor (EGFR), are recruited into clathrin-coated pits for internalization by endocytosis, which is relevant for signalling and/or receptor degradation. In liver cells, transforming growth factor-beta (TGF-beta) induces both pro- and anti-apoptotic signals; the latter are mediated by the EGFR pathway. Since EGFR mainly traffics via clathrin-coated vesicles, we aimed to analyse the potential role of clathrin in TGF-beta-induced signalling in liver cells and its relevance in liver cancer. Methods: Real-Time PCR and immunohistochemistry were used to analyse clathrin heavy-chain expression in human (CLTC) and mice (Cltc) liver tumours. Transient knockdown (siRNA) or overexpression of CLTC were used to analyse its role on TGF-beta and EGFR signalling in vitro. Bioinformatic analysis was used to determine the effect of CLTC and TGEB1 expression on prognosis and overall survival in patients with hepatocellular carcinoma (HCC). Results: Clathrin expression increased during liver tumorigenesis in humans and mice. CLTC knockdown cells responded to TGF-beta phosphorylating SMADs (canonical signalling) but showed impairment in the anti-apoptotic signals (EGFR transactivation). Experiments of loss or gain of function in HCC cells reveal an essential role for clathrin in inhibiting TGF-beta-induced apoptosis and upregulation of its pro-apoptotic target NOX4. Autocrine TGF-beta signalling in invasive HCC cells upregulates CLTC expression, switching its role to pro-tumorigenic. A positive correlation between TGEB1 and CLTC was found in HCC cells and patients. Patients expressing high levels of TGEB1 and CLTC had a worse prognosis and lower overall survival. Conclusions: This work describes a novel role for clathrin in liver tumorigenesis, favouring non-canonical pro-tumorigenic TGF-beta pathways. CLTC expression in human HCC samples could help select patients that would benefit from TGF-beta-targeted therapy. Lay summary: Clathrin heavy-chain expression increases during liver tumorigenesis in humans (CLTC) and mice (Mc), altering the cellular response to TGF-beta in favour of anti-apoptotic/pro-tumorigenic signals. A positive correlation between TGEB1 and CLTC was found in HCC cells and patients. Patients expressing high levels of TGEB1 and CLTC had a worse prognosis and lower overall survival. CLTC expression in HCC human samples could help select patients that would benefit from therapies targeting TGF-beta. (C) 2019 European Association for the Study of the Liver. Published by Elsevier B.

In COPD, airway acidification is a common phenomenon associated with decreased antibacterial activity and persistent bacterial colonization. GPR4 is a proton sensing G protein-coupled receptor highly expressed on endothelial cells that induces a signaling cascade via coupling to Gs/cAMP formation and serves as an important interface between airway acidification and inflammation. Here we present the characterization of a short-term mouse model that mimics several of the pathophysiological features observed in bacterial COPD exacerbations in humans, rendering it very useful for pharmacological studies. Additionally, we report that inhibition of GPR4 by a small molecule antagonist (Miltz et al., 2017) rescues some of these manifestations. Mice received porcine pancreatic elastase (0.4U) intratracheally (i.t.) at day 0 to induce emphysema. After 10 days to allow resolution of acute inflammation, lipopolysaccharide (2mg/kg) was administrated i.t. to mimic acute bacterial exacerbation. Treatment with the GPR4 inhibitor started 1 day later (twice daily for 4 days, 100mg/kg, per os). Our emphysema-exacerbation model recapitulates many hallmarks of human COPD exacerbation within 2 weeks e.g. small airway remodeling, increased mucus production, lung permeability and edema, induced cytokines and proteases release and significant airway obstruction (FEV100ms/FVC). In this model, GPR4 inhibition significantly reduced lung permeability, immune cells influx, pro-inflammatory cytokines, detrimental mucin MUC5AC and proteases MMP9/12. To conclude, we characterized a short-term mouse model of emphysema-exacerbation with useful properties for pharmacological research; moreover, we show that GPR4 inhibition is a promising approach for reducing severity of acute COPD exacerbations.

Background & aims Bone morphogenetic protein 9 (BMP9) interferes with liver regeneration upon acute injury, while promoting fibrosis upon carbon tetrachloride-induced chronic injury. We have now addressed the role of BMP9 in 3,5 diethoxicarbonyl-1,4 dihydrocollidine (DDC)-induced cholestatic liver injury, a model of liver regeneration mediated by hepatic progenitor cell (known as oval cell), exemplified as ductular reaction and oval cell expansion. Methods WT and BMP9KO mice were submitted to DDC diet. Livers were examined for liver injury, fibrosis, inflammation and oval cell expansion by serum biochemistry, histology, RT-qPCR and western blot. BMP9 signalling and effects in oval cells were studied in vitro using western blot and transcriptional assays, plus functional assays of DNA synthesis, cell viability and apoptosis. Crosslinking assays and short hairpin RNA approaches were used to identify the receptors mediating BMP9 effects. Results Deletion of BMP9 reduces liver damage and fibrosis, but enhances inflammation upon DDC feeding. Molecularly, absence of BMP9 results in overactivation of PI3K/AKT, ERK-MAPKs and c-Met signalling pathways, which together with an enhanced ductular reaction and oval cell expansion evidence an improved regenerative response and decreased damage in response to DDC feeding. Importantly, BMP9 directly targets oval cells, it activates SMAD1,5,8, decreases cell growth and promotes apoptosis, effects that are mediated by Activin Receptor-Like Kinase 2 (ALK2) type I receptor. Conclusions We identify BMP9 as a negative regulator of oval cell expansion in cholestatic injury, its deletion enhancing liver regeneration. Likewise, our work further supports BMP9 as an attractive therapeutic target for chronic liver diseases.

Bone Morphogenetic Proteins (BMPs) belong to the Transforming Growth Factor-β (TGF-β) family. Initially identified due to their ability to induce bone formation, they are now known to have multiple functions in a variety of tissues, being critical not only during development for tissue morphogenesis and organogenesis but also during adult tissue homeostasis. This review focus on the liver as a target tissue for BMPs actions, devoting most efforts to summarize our knowledge on their recently recognized and/or emerging roles on regulation of the liver regenerative response to various insults, either acute or chronic and their effects on development and progression of liver fibrosis in different pathological conditions. In an attempt to provide the basis for guiding research efforts in this field both the more solid and more controversial areas of research were highlighted.

Different data support a role for the epidermal growth factor receptor (EGFR) pathway during liver regeneration and hepatocarcinogenesis. However, important issues, such as the precise mechanisms mediating its actions and the unique versus redundant functions, have not been fully defined. Here, we present a novel transgenic mouse model expressing a hepatocyte-specific truncated form of human EGFR, which acts as negative dominant mutant (ΔEGFR) and allows definition of its tyrosine kinase-dependent functions. Results indicate a critical role for EGFR catalytic activity during the early stages of liver regeneration. Thus, after two-thirds partial hepatectomy, ΔEGFR livers displayed lower and delayed proliferation and lower activation of proliferative signals, which correlated with overactivation of the transforming growth factor-β pathway. Altered regenerative response was associated with amplification of cytostatic effects of transforming growth factor-β through induction of cell cycle negative regulators. Interestingly, lipid synthesis was severely inhibited in ΔEGFR livers after partial hepatectomy, revealing a new function for EGFR kinase activity as a lipid metabolism regulator in regenerating hepatocytes. In spite of these profound alterations, ΔEGFR livers were able to recover liver mass by overactivating compensatory signals, such as c-Met. Our results also indicate that EGFR catalytic activity is critical in the early preneoplastic stages of the liver because ΔEGFR mice showed a delay in the appearance of diethyl-nitrosamine-induced tumors, which correlated with decreased proliferation and delay in the diethyl-nitrosamine-induced inflammatory process. Conclusion: These studies demonstrate that EGFR catalytic activity is critical during the initial phases of both liver regeneration and carcinogenesis and provide key mechanistic insights into how this kinase acts to regulate liver pathophysiology. (Hepatology 2016;63:604-619), Cofunded by the Ministry of Economy and Competitiveness-MINECO and the European Regional Development Fund-FEDER, Spain (Contract grant numbers: BFU2012-35538 and ISCIII-RTICC RD12-0036-0029 to I.F.-IDIBELL; SAF2009-12477 to A.S.-UCM/IdISSC; RETICS-RD12/0019/0023 and SAF2011-30526-C02-01 to J.-C.S.-CIEMAT/CIBERER/IIS-FJD; SAF2012-33283 to A.M.V.-CSIC/CIBERDEM). People Programme (Marie Curie Actions) of the FP7-2012, under REA grant agreement #PITN-GA-2012-316549 (IT-LIVER) to I.F.-IDIBELL and to A.S.-UCM/IdISSC. AGAUR-Generalitat de Catalunya to I.F-IDIBELL (Contract grant number: 2009SGR-312). Dirección General de Investigación de la Comunidad de Madrid, Spain (Contract grant number S2010/BMD-2402 to A.S.-UCM/IdISSC). Fundación Eugenio Rodríguez Pascual to M.G.-B.-CIEMAT/CIBERER/IIS-FJD. J.L.-L. was recipient of a predoctoral fellowship from IDIBELL; D.C.-D. and A.M.-P. were recipients of predoctoral fellowships from MINECO, Spain (Contract grant number: FPI - BES-2013-064609 and BES-2007-16187, respectively).

The study of bone morphogenetic proteins (BMPs) role in tumorigenic processes, and specifically in the liver, has gathered importance in the last few years. Previous studies have shown that BMP9 is overexpressed in about 40% of hepatocellular carcinoma (HCC) patients. In vitro data have also shown evidence that BMP9 has a pro-tumorigenic action, not only by inducing epithelial to mesenchymal transition (EMT) and migration, but also by promoting proliferation and survival in liver cancer cells. However, the precise mechanisms driving these effects have not yet been established. In the present work, we deepened our studies into the intracellular mechanisms implicated in the BMP9 proliferative and pro-survival effect on liver tumor cells. In HepG2 cells, BMP9 induces both Smad and non-Smad signaling cascades, specifically PI3K/AKT and p38MAPK. However, only the p38MAPK pathway contributes to the BMP9 growth-promoting effect on these cells. Using genetic and pharmacological approaches, we demonstrate that p38MAPK activation, although dispensable for the BMP9 proliferative activity, is required for the BMP9 protective effect on serum withdrawal-induced apoptosis. These findings contribute to a better understanding of the signaling pathways involved in the BMP9 pro-tumorigenic role in liver tumor cells.

Oval cells constitute an interesting hepatic cell population. They contribute to sustain liver regeneration during chronic liver damage, but in doing this they can be target of malignant conversion and become tumor-initiating cells and drive hepatocarcinogenesis. The molecular mechanisms beneath either their pro-regenerative or pro-tumorigenic potential are still poorly understood. In this study, we have investigated the role of the HGF/c-Met pathway in regulation of oval cell migratory and invasive properties. Our results show that HGF induces c-Met-dependent oval cell migration both in normal culture conditions and after in vitro wounding. HGF-triggered migration involves F-actin cytoskeleton reorganization, which is also evidenced by activation of Rac1. Furthermore, HGF causes ZO-1 translocation from cell–cell contact sites to cytoplasm and its concomitant activation by phosphorylation. However, no loss of expression of cell–cell adhesion proteins, including E-cadherin, ZO-1 and Occludin-1, is observed. Additionally, migration does not lead to cell dispersal but to a characteristic organized pattern in rows, in turn associated with Golgi compaction, providing strong evidence of a morphogenic collective migration. Besides migration, HGF increases oval cell invasion through extracellular matrix, a process that requires PI3K activation and is at least partly mediated by expression and activation of metalloproteases. Altogether, our findings provide novel insights into the cellular and molecular mechanisms mediating the essential role of HGF/c-Met signaling during oval cell-mediated mouse liver regeneration.