The matricellular protein CCN1 enhances TGF-β1/SMAD3-dependent profibrotic signaling in fibroblasts and contributes to fibrogenic responses to lung injury

Matricellular Protein CCN1 Promotes Collagen Alignment and Scar Integrity After Myocardial Infarction

BACKGROUND

Members of the cellular communication network family (CCN) of matricellular proteins, like CCN1, have long been implicated in the regulation of cellular processes underlying wound healing, tissue fibrogenesis, and collagen dynamics. While many studies suggest antifibrotic actions for CCN1 in the adult heart through the promotion of myofibroblast senescence, they largely relied on exogenous supplementation strategies in in vivo models of cardiac injury where its expression is already induced-which may confound interpretation of its function in this process. The objective of this study was to interrogate the role of the endogenous protein on fibroblast function, collagen structural dynamics, and its associated impact on cardiac fibrosis after myocardial infarction (MI).

METHODS/RESULTS

Here, we employed CCN1 loss-of-function methodologies, including both in vitro siRNA-mediated depletion and in vivo fibroblast-specific knockout mice to assess the role of the endogenous protein on cardiac fibroblast fibrotic signaling, and its involvement in acute scar formation after MI. In vitro depletion of CCN1 reduced cardiac fibroblast senescence and proliferation. Although depletion of CCN1 decreased the expression of collagen processing and stabilization enzymes (i.e., P4HA1, PLOD1, and PLOD2), it did not inhibit myofibroblast induction or type I collagen synthesis. Alone, fibroblast-specific removal of CCN1 did not negatively impact ventricular performance or myocardial collagen content but did contribute to disorganization of collagen fibrils and increased matrix compliance. Similarly, Ccn1 ablated animals subjected to MI showed no discernible alterations in cardiac structure or function one week after permanent coronary artery ligation, but exhibited marked increases in incidence of mortality and cardiac rupture. Consistent with our findings that CCN1 depletion does not assuage myofibroblast conversion or type I collagen synthesis in vitro, Ccn1 knockout animals revealed no measurable differences in collagen scar width or mass compared to controls; however, detailed structural analyses via SHG and TEM of scar regions revealed marked alterations in their scar collagen topography-exhibiting changes in numerous macro- and micro-level collagen architectural attributes. Specifically, Ccn1 knockout mice displayed heightened ECM structural complexity in post-MI scar regions, including diminished local alignment and heightened tortuosity of collagen fibers, as well as reduced organizational coherency, packing, and size of collagen fibrils. Associated with these changes in ECM topography with the loss of CCN1 were reductions in fibroblast-matrix interactions, as evidenced by reduced fibroblast nuclear and cellular deformation in vivo and reduced focal-adhesion formation in vitro; findings that ultimately suggest CCN1's ability to influence fibroblast-led collagen alignment may in part be credited to its capacity to augment fibroblast-matrix interactions.

CONCLUSIONS

These findings underscore the pivotal role of endogenous CCN1 in the scar formation process occurring after MI, directing the appropriate arrangement of the extracellular matrix's collagenous components in the maturing scar-shaping the mechanical properties that support its structural stability. While this suggests an adaptive role for CCN1 in regulating collagen structural attributes crucial for supporting scar integrity post MI, the long-term protracted expression of CCN1 holds maladaptive implications, potentially diminishing collagen structural complexity and compliance in non-infarct regions.

ABSTRACT (SHORT) BACKGROUND

The cellular communication network (CCN) family of matricellular proteins, including CCN1, plays a critical role in regulating cellular processes essential for wound healing, tissue fibrogenesis, and collagen dynamics. However, previous studies predominantly relied on exogenous supplementation strategies in in vivo models of cardiac injury, potentially confounding interpretations of CCN1's function in these processes. This study aimed to investigate the endogenous protein's role in fibroblast function, collagen structural dynamics, and its impact on cardiac fibrosis following myocardial infarction (MI).

METHODS/RESULTS

Employing CCN1 loss-of-function approaches, including in vitro siRNA-mediated depletion and in vivo fibroblast-specific knockout mice, we assessed CCN1's influence on cardiac fibroblast fibrotic signaling and acute scar formation post-MI. In vitro CCN1 depletion reduced cardiac fibroblast senescence and proliferation, as well as decreased the expression of enzymes crucial for collagen processing and stabilization. In vivo fibroblast-specific CCN1 removal did not impair ventricular performance or alter myocardial collagen content but led to collagen fibril disorganization and increased matrix compliance. Ccn1 knockout animals exhibited elevated mortality and cardiac rupture post-MI, with no significant differences in collagen scar width or mass compared to wildtype controls. Yet, detailed structural analyses revealed alterations in scar collagen topography, including increased ECM structural complexity and diminished collagen alignment. These changes correlated with reduced fibroblast-matrix interactions, suggesting CCN1's role in influencing collagen alignment through augmenting these interactions.

CONCLUSIONS

Endogenous CCN1 plays a pivotal role in scar formation post-MI by orchestrating the arrangement of collagenous components in the maturing scar, thereby shaping its mechanical properties and structural stability. While CCN1's adaptive role in regulating collagen structural attributes crucial for scar integrity is evident, prolonged expression may lead to diminished collagen structural complexity and compliance in non-infarct regions, highlighting potential maladaptive implications in the long-term.

TGF-β1-triggered BMI1 and SMAD2 cooperatively regulate miR-191 to modulate bone formation

Transforming growth factor β 1 (TGF-β1), as the most abundant signaling molecule in bone matrix, is essential for bone homeostasis. However, the signaling transduction of TGF-β1 in the bone-forming microenvironment remains unknown. Here, we showed that microRNA-191 (miR-191) was downregulated during osteogenesis and further decreased by osteo-favoring TGF-β1 in bone marrow mesenchymal stem cells (BMSCs). MiR-191 was lower in bone tissues from children than in those from middle-aged individuals and it was negatively correlated with collagen type I alpha 1 chain (COL1A1). MiR-191 depletion significantly increased osteogenesis and bone formation in vivo. Hydrogels embedded with miR-191-low BMSCs displayed a powerful bone repair effect. Mechanistically, transcription factors BMI1 and SMAD2 coordinately controlled miR-191 level. In detail, BMI1 and pSMAD2 were both upregulated by TGF-β1 under osteogenic condition. SMAD2 activated miR-191 transcription, while BMI1 competed with SMAD2 for binding to miR-191 promoter region, thus disturbing the activation of SMAD2 on miR-191 and reducing miR-191 level. Altogether, our findings reveal that miR-191 regulated by TGF-β1-induced BMI1 and SMAD2 negatively modulated bone formation and regeneration, and inhibition of miR-191 might be therapeutically useful to enhance bone repair in clinic.

Prognostic Function and Immunologic Landscape of a Predictive Model Based on Five Senescence-Related Genes in IPF Bronchoalveolar Lavage Fluid

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a type of interstitial lung disease characterized by unknown causes and a poor prognosis. Recent research indicates that age-related mechanisms, such as cellular senescence, may play a role in the development of this condition. However, the relationship between cellular senescence and clinical outcomes in IPF remains uncertain.

METHODS

Data from the GSE70867 database were meticulously analyzed in this study. The research employed differential expression analysis, as well as univariate and multivariate Cox regression analysis, to pinpoint senescence-related genes (SRGs) linked to prognosis and construct a prognostic risk model. The model's clinical relevance and its connection to potential biological processes were systematically assessed in training and testing datasets. Additionally, the expression location of prognosis-related SRGs was identified through immunohistochemical staining, and the correlation between SRGs and immune cell infiltration was deduced using the GSE28221 dataset.

RESULT

The prognostic risk model was constructed based on five SRGs (cellular communication network factor 1, CYR61, stratifin, SFN, megakaryocyte-associated tyrosine kinase, MATK, C-X-C motif chemokine ligand 1, CXCL1, LIM domain, and actin binding 1, LIMA1). Both Kaplan-Meier (KM) curves (p = 0.005) and time-dependent receiver operating characteristic (ROC) analysis affirmed the predictive accuracy of this model in testing datasets, with respective areas under the ROC curve at 1-, 2-, and 3-years being 0.721, 0.802, and 0.739. Furthermore, qRT-RCR analysis and immunohistochemical staining verify the differential expression of SRGs in IPF samples and controls. Moreover, patients in the high-risk group contained higher infiltration levels of neutrophils, eosinophils, and M1 macrophages in BALF, which appeared to be independent indicators of poor prognosis in IPF patients.

CONCLUSION

Our research reveals the effectiveness of the 5 SRGs model in BALF for risk stratification and prognosis prediction in IPF patients, providing new insights into the immune infiltration of IPF progression.

Upregulation of CYR61 by TGF-β and YAP signaling exerts a counter-suppression of hepatocellular carcinoma

Transforming growth factor-β (TGF-β) and Hippo signaling are two critical pathways engaged in cancer progression by regulating both oncogenes and tumor suppressors, yet how the two pathways coordinately exert their functions in the development of hepatocellular carcinoma (HCC) remains elusive. In this study, we firstly conducted an integrated analysis of public liver cancer databases and our experimental TGF-β target genes, identifying CYR61 as a pivotal candidate gene relating to HCC development. The expression of CYR61 is downregulated in clinical HCC tissues and cell lines than that in the normal counterparts. Evidence revealed that CYR61 is a direct target gene of TGF-β in liver cancer cells. In addition, TGF-β-stimulated Smad2/3 and the Hippo pathway downstream effectors YAP and TEAD4 can form a protein complex on the promoter of CYR61, thereby activating the promoter activity and stimulating CYR61 gene transcription in a collaborative manner. Functionally, depletion of CYR61 enhanced TGF-β- or YAP-mediated growth and migration of liver cancer cells. Consistently, ectopic expression of CYR61 was capable of impeding TGF-β- or YAP-induced malignant transformation of HCC cells in vitro and attenuating HCC xenograft growth in nude mice. Finally, transcriptomic analysis indicates that CYR61 can elicit an antitumor program in liver cancer cells. Together, these results add new evidence for the crosstalk between TGF-β and Hippo signaling and unveil an important tumor suppressor function of CYR61 in liver cancer.

Back to the future: targeting the extracellular matrix to treat systemic sclerosis

Fibrosis is the excessive deposition of a stable extracellular matrix (ECM); fibrotic tissue is composed principally of highly crosslinked type I collagen and highly contractile myofibroblasts. Systemic sclerosis (SSc) is a multisystem autoimmune connective tissue disease characterized by skin and organ fibrosis. The fibrotic process has been recognized in SSc for >40 years, but drugs with demonstrable efficacy against SSc fibrosis in ameliorating the lung involvement have only recently been identified. Unfortunately, these treatments are ineffective at improving the skin score in patients with SSc. Previous clinical trials in SSc have largely focused on the cross-purposing of anti-inflammatory drugs and the use of immunosuppressive drugs from the transplantation field, which address inflammatory and/or autoimmune processes. Limited examination has taken place of specific anti-fibrotic agents developed through their ability to directly target the ECM in SSc by, for example, alleviating the persistent matrix stiffness and mechanotransduction that might be required for both the initiation and maintenance of fibrosis, including in SSc. However, because of the importance of the ECM in the SSc phenotype, attempts have now been made to identify drugs that specifically target the ECM, including some drugs that are currently under consideration for the treatment of cancer.

Identification of Hub Genes in Idiopathic Pulmonary Fibrosis and Their Association with Lung Cancer by Bioinformatics Analysis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and irreversible disease with a high mortality rate worldwide. However, the etiology and pathogenesis of IPF have not yet been fully described. Moreover, lung cancer is a significant complication of IPF and is associated with increased mortality. Nevertheless, identifying common genes involved in developing IPF and its progression to lung cancer remains an unmet need. The present study aimed to identify hub genes related to the development of IPF by meta-analysis. In addition, we analyzed their expression and their relationship with patients' progression in lung cancer.

METHOD

Microarray datasets GSE24206, GSE21369, GSE110147, GSE72073, and GSE32539 were downloaded from Gene Expression Omnibus (GEO). Next, we conducted a series of bioinformatics analysis to explore possible hub genes in IPF and evaluated the expression of hub genes in lung cancer and their relationship with the progression of different stages of cancer.

RESULTS

A total of 1888 differentially expressed genes (DEGs) were identified, including 1105 upregulated and 783 downregulated genes. The 10 hub genes that exhibited a high degree of connectivity from the PPI network were identified. Analysis of the KEGG pathways showed that hub genes correlate with pathways such as the ECM-receptor interaction. Finally, we found that these hub genes are expressed in lung cancer and are associated with the progression of different stages of lung cancer.

CONCLUSIONS

Based on the integration of GEO microarray datasets, the present study identified DEGs and hub genes that could play an essential role in the pathogenesis of IPF and its association with the development of lung cancer in these patients, which could be considered potential diagnostic biomarkers or therapeutic targets for the disease.

Long-term cadmium exposure induces chronic obstructive pulmonary disease-like lung lesions in a mouse model

Accumulating evidences demonstrate that long-term exposure to atmospheric fine particles and air pollutants elevates the risk of chronic obstructive pulmonary disease (COPD). Cadmium (Cd) is one of the important toxic substances in atmospheric fine particles and air pollutants. In this study, we aimed to establish a mouse model to evaluate whether respiratory Cd exposure induces COPD-like lung injury. Adult male C57BL/6 mice were exposed to CdCl₂ (10 mg/L, 4 h per day) by inhaling aerosol for either 10 weeks (short-term) or 6 months (long-term). The mean serum Cd concentration was 6.26 μg/L in Cd-exposed mice. Lung weight and coefficient were elevated in long-term Cd-exposed mice. Pathological scores and alveolar destructive indices were increased in long-term Cd-exposed mouse lungs. Mean linear intercept and airway wall thickness were accordingly elevated in Cd-exposed mice. Inflammatory cell infiltration was obvious and inflammatory cytokines, including TNF-α, IL-1β, IL-6, IL-8, IL-10 and TGF-β, were up-regulated in Cd-exposed mouse lungs. α-SMA, N-cadherin and vimentin, epithelial-mesenchymal transition markers, and extracellular matrix collagen deposition around small airway, determined by Masson's trichrome staining, were shown in Cd-exposed mouse lungs. COPD-characteristic lung function decline was observed in long-term Cd-exposed mice. These outcomes show that long-term respiratory exposure to Cd induces COPD-like lung lesions for the first time.

Extracellular Targets to Reduce Excessive Scarring in Response to Tissue Injury

Excessive scar formation is a hallmark of localized and systemic fibrotic disorders. Despite extensive studies to define valid anti-fibrotic targets and develop effective therapeutics, progressive fibrosis remains a significant medical problem. Regardless of the injury type or location of wounded tissue, excessive production and accumulation of collagen-rich extracellular matrix is the common denominator of all fibrotic disorders. A long-standing dogma was that anti-fibrotic approaches should focus on overall intracellular processes that drive fibrotic scarring. Because of the poor outcomes of these approaches, scientific efforts now focus on regulating the extracellular components of fibrotic tissues. Crucial extracellular players include cellular receptors of matrix components, macromolecules that form the matrix architecture, auxiliary proteins that facilitate the formation of stiff scar tissue, matricellular proteins, and extracellular vesicles that modulate matrix homeostasis. This review summarizes studies targeting the extracellular aspects of fibrotic tissue synthesis, presents the rationale for these studies, and discusses the progress and limitations of current extracellular approaches to limit fibrotic healing.

Astragaloside IV improves pulmonary arterial hypertension by increasing the expression of CCN1 and activating the ERK1/2 pathway

The aim of the present study was to investigate the underlying mechanism of AS-IV and CCN1 in PAH and to evaluate whether the protective effect of AS-IV against PAH is associated with CCN1 and its related signalling pathway. In vivo, male SD rats were intraperitoneally injected with monocrotaline (MCT, 60 mg/kg) or exposed to hypoxia (10% oxygen) and gavaged with AS-IV (20, 40 and 80 mg/kg/day) to create a PAH model. In vitro, human pulmonary artery endothelial cells (hPAECs) were exposed to hypoxia (3% oxygen) or monocrotaline pyrrole (MCTP, 60 μg/mL) and treated with AS-IV (10, 20 and 40 μM), EGF (10 nM, ERK agonist), small interfering CCN1 (CCN1 siRNA) and recombinant CCN1 protein (rCCN1, 100 ng/mL). We identified the differences in the expression of genes in the lung tissues of PAH rats by proteomics. At the same time, we dynamically detected the expression of CCN1 by Western blot both in vivo and in vitro. The Western blot experimental results showed that the expression of CCN1 increased in the early stage of PAH and decreased in the advanced stage of PAH. The results showed that compared with the control group, MCT- and hypoxia-induced increased the hemodynamic parameters and apoptosis. AS-IV can improve PAH, as characterized by decreased hemodynamic parameters, vascular wall area ratio (WA%), vascular wall thickness ratio (WT%) and α-SMA expression and inhibition of cell apoptosis. Moreover, the improvement of PAH by AS-IV was accompanied by increased CCN1 expression, which activated the ERK1/2 signalling pathway. Meanwhile, CCN1 and p-ERK1/2 were inhibited by siCCN1 and promoted by rCCN1. EGF not only activated the ERK1/2 signalling pathway but also induced the expression of CCN1. In conclusion, AS-IV improves PAH by increasing the expression of CCN1 and activating the ERK1/2 signalling pathway. The results of our study provide a theoretical basis for additional study on the protective effect of AS-IV against PAH.

Upregulation of GLT25D1 in Hepatic Stellate Cells Promotes Liver Fibrosis via the TGF-β1/SMAD3 Pathway In Vivo and In vitro

BACKGROUND AND AIMS

Collagen β(1-O) galactosyltransferase 25 domain 1 (GLT25D1) is associated with collagen production and glycosylation, and its knockout in mice results in embryonic death. However, its role in liver fibrosis remains elusive, particularly in hepatic stellate cells (HSCs), the primary collagen-producing cells associated with liver fibrogenesis. Herein, we aimed to elucidate the role of GLT25D1 in HSCs.

METHODS

Bile duct ligation (BDL)-induced mouse liver fibrosis models, primary mouse HSCs (mHSCs), and transforming growth factor beta 1 (TGF-β1)-stimulated LX-2 human hepatic stellate cells were used in in vivo and in vitro studies. Stable LX-2 cell lines with either GLT25D1 overexpression or knockdown were established using lentiviral transfection. RNA-seq was performed to investigate the genomic differences. HPLC-MS/MS were used to identify glycosylation sites. Scanning electronic microscopy (SEM) and second-harmonic generation/two-photon excited fluorescence (SHG/TPEF) were used to image collagen fibril morphology.

RESULTS

GLT25D1 expression was upregulated in nonparenchymal cells in human cirrhotic liver tissues. Meanwhile, its knockdown attenuated collagen deposition in BDL-induced mouse liver fibrosis and inhibited mHSC activation. GLT25D1 was overexpressed in activated versus quiescence LX-2 cells and regulated in vitro LX-2 cell activation, including proliferation, contraction, and migration. GLT25D1 also significantly increased liver fibrogenic gene and protein expression. GLT25D1 upregulation promoted HSC activation and enhanced collagen expression through the TGF-β1/SMAD signaling pathway. Mass spectrometry showed that GLT25D1 regulated the glycosylation of collagen in HSCs, affecting the diameter of collagen fibers.

CONCLUSIONS

Collectively, the upregulation of GLT25D1 in HSCs promoted the progression of liver fibrosis by affecting HSCs activation and collagen stability.

Co-Expression Analysis of Airway Epithelial Transcriptome in Asthma Patients with Eosinophilic vs. Non-Eosinophilic Airway Infiltration

Asthma heterogeneity complicates the search for targeted treatment against airway inflammation and remodeling. We sought to investigate relations between eosinophilic inflammation, a phenotypic feature frequent in severe asthma, bronchial epithelial transcriptome, and functional and structural measures of airway remodeling. We compared epithelial gene expression, spirometry, airway cross-sectional geometry (computed tomography), reticular basement membrane thickness (histology), and blood and bronchoalveolar lavage (BAL) cytokines of n = 40 moderate to severe eosinophilic (EA) and non-eosinophilic asthma (NEA) patients distinguished by BAL eosinophilia. EA patients showed a similar extent of airway remodeling as NEA but had an increased expression of genes involved in the immune response and inflammation (e.g., KIR3DS1), reactive oxygen species generation (GYS2, ATPIF1), cell activation and proliferation (ANK3), cargo transporting (RAB4B, CPLX2), and tissue remodeling (FBLN1, SOX14, GSN), and a lower expression of genes involved in epithelial integrity (e.g., GJB1) and histone acetylation (SIN3A). Genes co-expressed in EA were involved in antiviral responses (e.g., ATP1B1), cell migration (EPS8L1, STOML3), cell adhesion (RAPH1), epithelial-mesenchymal transition (ASB3), and airway hyperreactivity and remodeling (FBN3, RECK), and several were linked to asthma in genome- (e.g., MRPL14, ASB3) or epigenome-wide association studies (CLC, GPI, SSCRB4, STRN4). Signaling pathways inferred from the co-expression pattern were associated with airway remodeling (e.g., TGF-β/Smad2/3, E2F/Rb, and Wnt/β-catenin).

Combined role for YAP-TEAD and YAP-RUNX2 signalling in substrate-stiffness regulation of cardiac fibroblast proliferation

Cardiac fibrosis is associated with increased stiffness of the myocardial extracellular matrix (ECM) in part mediated by increased cardiac fibroblast proliferation However, our understanding of the mechanisms regulating cardiac fibroblast proliferation are incomplete. Here we characterise a novel mechanism involving a combined activation of Yes-associated protein (YAP) targets RUNX Family Transcription Factor 2 (RUNX2) and TEA Domain Transcription Factor (TEAD). We demonstrate that cardiac fibroblast proliferation is enhanced by interaction with a stiff ECM compared to a soft ECM. This is associated with activation of the transcriptional co-factor, YAP. We demonstrate that this stiffness induced activation of YAP enhances the transcriptional activity of both TEAD and RUNX2 transcription factors. Inhibition of either TEAD or RUNX2, using gene silencing, expression of dominant-negative mutants or pharmacological inhibition, reduces cardiac fibroblast proliferation. Using mutants of YAP, defective in TEAD or RUNX2 activation ability, we demonstrate a dual role of YAP-mediated activation of TEAD and RUNX2 for substrate stiffness induced cardiac fibroblast proliferation. Our data highlights a previously unrecognised role of YAP mediated RUNX2 activation for cardiac fibroblast proliferation in response to increased ECM stiffness.

Cross-sectional and longitudinal associations of serum Cysteine-rich 61 with severity and prognosis among community-acquired pneumonia patients in China

Background

Cysteine-rich 61 (CYR61) is implicated in many pulmonary diseases. However, the relationship between CYR61 and community-acquired pneumonia (CAP) patients was unknown. This research aimed to estimate the correlations of serum CYR61 with severity and prognosis in CAP patients through a prospective cohort study.

Methods

All 541 CAP patients were enrolled in this study. Fasting venous blood was collected. Clinical characteristics and demographic information were obtained. CYR61 and inflammatory cytokines were detected in serum using ELISA.

Results

Serum CYR61 was gradually increased in parallel with severity scores in CAP patients. Correlative analysis indicated that serum CYR61 was strongly associated with many clinical parameters in CAP patients. Moreover, mixed logistic and linear regression models found that there were positive correlations between serum CYR61 and CAP severity scores after adjusted for age, BMI, and respiratory rate. Stratified analyses suggested that age affected the associations between serum CYR61 and severity scores. On admission, higher serum CYR61 levels elevated the risks of mechanical ventilation, vasoactive agent, ICU admission, death, and longer hospital stays during hospitalization. Moreover, serum CYR61 in combination with severity scores upregulated the predictive capacities for severity and death than single serum CYR61 or severity scores in CAP patients.

Conclusion

There are significantly positive dose-response associations of serum CYR61 on admission with the severity and adverse prognostic outcomes, demonstrating that CYR61 is involved in the pathophysiology of CAP. Serum CYR61 may be used as a potential biomarker for the diagnosis and prognosis in CAP patients.

Ethanol extract of Pharbitis nil ameliorates liver fibrosis through regulation of the TGFβ1-SMAD2/3 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Pharbitis nil (L.) Choisy is a medicinal herb, and herbal remedies based on its seeds have been used to treat of obesity and liver diseases, including fatty liver and liver cirrhosis in East Asia.

AIM OF THE STUDY

Liver fibrosis is a major cause of morbidity and mortality in patients with chronic liver inflammation such as that caused by non-alcoholic steatohepatitis. However, no effective pharmaceutical treatment for liver fibrosis has been approved. In this study, we aimed to investigate that ethanol extract of pharbitis nil (PNE) alleviates the liver fibrosis.

MATERIALS AND METHODS

We studied the effects of PNE on two preclinical models. Six-week-old male C57BL/6 mice were intraperitoneally injected with CCl₄ twice weekly for 6 weeks and then treated with 5 or 10 mg/kg PNE daily from week 3 for weeks. Secondly, mice were fed HFD for 41 weeks and at 35 weeks treated with 5 mg/kg PNE daily for the remaining 6 weeks. In addition, we examined the antifibrotic effects of PNE in primary mouse hepatic stellate cells and LX-2 cells.

RESULTS

PNE treatment ameliorated hepatocyte necrosis, inflammation, and liver fibrosis in CCl₄-treated mice and inhibited the progression of liver fibrosis in mice with HFD-induced fibrosis. PNE reduced the expressions of fibrosis markers and SMAD2/3 activations in mouse livers and in TGFβ1-treated primary mouse hepatic stellate and LX-2 cells CONCLUSIONS: This study demonstrates that PNE attenuates liver fibrosis by downregulating TGFβ1-induced SMAD2/3 activation.

Specific epigenetic regulators serve as potential therapeutic targets in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF), a disorder observed mostly in older human beings, is characterised by chronic and progressive lung scarring leading to an irreversible decline in lung function. This health condition has a dismal prognosis and the currently available drugs only delay but fail to reverse the progression of lung damage. Consequently, it becomes imperative to discover improved therapeutic compounds and their cellular targets to cure IPF. In this regard, a number of recent studies have targeted the epigenetic regulation by histone deacetylases (HDACs) to develop and categorise antifibrotic drugs for lungs. Therefore, this review focuses on how aberrant expression or activity of Classes I, II and III HDACs alter TGF-β signalling to promote events such as epithelial-mesenchymal transition, differentiation of activated fibroblasts into myofibroblasts, and excess deposition of the extracellular matrix to propel lung fibrosis. Further, this study describes how certain chemical compounds or dietary changes modulate dysregulated HDACs to attenuate five faulty TGF-β-dependent profibrotic processes, both in animal models and cell lines replicating IPF, thereby identifying promising means to treat this lung disorder.

Matrix-bound Cyr61/CCN1 is required to retain the properties of the bone marrow mesenchymal stem cell niche but is depleted with aging

Previously, we showed that extracellular matrices (ECMs), produced ex vivo by various types of stromal cells, direct bone marrow mesenchymal stem cells (BM-MSCs) in a tissue-specific manner and recapitulate physiologic changes characteristic of the aging microenvironment. In particular, BM-MSCs obtained from elderly donors and cultured on ECM produced by young BM stromal cells showed improved quantity, quality and osteogenic differentiation. In the present study, we searched for matrix components that are required for a functional BM-MSC niche by comparing ECMs produced by BM stromal cells from "young" (≤25 y/o) versus "elderly" (≥60 y/o) donors. With increasing donor age, ECM fibrillar organization and mechanical integrity deteriorated, along with the ability to promote BM-MSC proliferation and responsiveness to growth factors. Proteomic analyses revealed that the matricellular protein, Cyr61/CCN1, was present in young, but undetectable in elderly, BM-ECM. To assess the role of Cyr61 in the BM-MSC niche, we used genetic methods to down-regulate the incorporation of Cyr61 during production of young ECM and up-regulate its incorporation in elderly ECM. The results showed that Cyr61-depleted young ECM lost the ability to promote BM-MSC proliferation and growth factor responsiveness. However, up-regulating the incorporation of Cyr61 during synthesis of elderly ECM restored its ability to support BM-MSC responsiveness to osteogenic factors such as BMP-2 and IGF-1. We next examined aging bone and compared bone mineral density and Cyr61 content of L4-L5 vertebral bodies in "young" (9-11 m/o) and "elderly" (21-33 m/o) mice. Our analyses showed that low bone mineral density was associated with decreased amounts of Cyr61 in osseous tissue of elderly versus young mice. Our results strongly demonstrate a novel role for ECM-bound Cyr61 in the BM-MSC niche, where it is responsible for retention of BM-MSC proliferation and growth factor responsiveness, while depletion of Cyr61 from the BM niche contributes to an aging-related dysregulation of BM-MSCs. Our results also suggest new potential therapeutic targets for treating age-related bone loss by restoring specific ECM components to the stem cell niche.

Association of Ligamentum Flavum Hypertrophy with Adolescent Idiopathic Scoliosis Progression-Comparative Microarray Gene Expression Analysis

The role of the ligamentum flavum (LF) in the pathogenesis of adolescent idiopathic scoliosis (AIS) is not well understood. Using magnetic resonance imaging (MRI), we investigated the degrees of LF hypertrophy in 18 patients without scoliosis and on the convex and concave sides of the apex of the curvature in 22 patients with AIS. Next, gene expression was compared among neutral vertebral LF and LF on the convex and concave sides of the apex of the curvature in patients with AIS. Histological and microarray analyses of the LF were compared among neutral vertebrae (control) and the LF on the apex of the curvatures. The mean area of LF in the without scoliosis, apical concave, and convex with scoliosis groups was 10.5, 13.5, and 20.3 mm2, respectively. There were significant differences among the three groups (p < 0.05). Histological analysis showed that the ratio of fibers (Collagen/Elastic) was significantly increased on the convex side compared to the concave side (p < 0.05). Microarray analysis showed that ERC2 and MAFB showed significantly increased gene expression on the convex side compared with those of the concave side and the neutral vertebral LF cells. These genes were significantly associated with increased expression of collagen by LF cells (p < 0.05). LF hypertrophy was identified in scoliosis patients, and the convex side was significantly more hypertrophic than that of the concave side. ERC2 and MAFB genes were associated with LF hypertrophy in patients with AIS. These phenomena are likely to be associated with the progression of scoliosis.

GANE can Improve Lung Fibrosis by Reducing Inflammation via Promoting p38MAPK/TGF-β1/NF-κB Signaling Pathway Downregulation

There is a trend to use nanoparticles as distinct treatments for cancer treatment because they have overcome many of the limitations of traditional drug delivery systems. Gallic acid (GA) is an effective polyphenol in the treatment of tissue injuries. In this study, GA was loaded onto niosomes to produce gallic acid nanoemulsion (GANE) using a green synthesis technique. GANE's efficiency, morphology, UV absorption, release, and Fourier-transform infrared spectroscopy (FTIR) analysis were evaluated. An in vitro study was conducted on the A549 lung carcinoma cell line to determine the GANE cytotoxicity. Also, our study was extended to evaluate the protective effect of GANE against lipopolysaccharide (LPS)-induced pulmonary fibrosis in rats. GANE showed higher encapsulation efficiency and strong absorption at 280 nm. Transmission electron microscopy presented a spherical shape of the prepared nanoparticles, and FTIR demonstrated different spectra for the free gallic acid sample compared to GANE. GANE showed cytotoxicity for the A549 carcinoma lung cell line with a low IC₅₀ value. It was found that oral administration of GANE at 32.8 and 82 mg/kg.b.w. and dexamethasone (0.5 mg/kg) provided significant protection against LPS-induced pulmonary fibrosis. GANE enhanced production of superoxide dismutase, GPx, and GSH. It simultaneously reduced the MDA level. The GANE and dexamethasone, induced the production of IL-4, but suppressed TNF-α and IL-6. On the other hand, the lung p38MAPK, TGF-β1, and NF-κB gene expression was downregulated in rats administrated with GANE when compared with the LPS-treated rats. Histological studies confirmed the effective effect of GANE as it had a lung-protective effect against LPS-induced lung fibrosis. It was noticed that GANE can inhibit oxidative stress, lipid peroxidation, and cytokines and downregulate p38MAPK, TGF-β1, and NF-κB gene expression to suppress the proliferation and migration of lung fibrotic cells.

Serum CYR61 Is Associated With Airway Inflammation and Is a Potential Biomarker for Severity in Chronic Obstructive Pulmonary Disease

Background: Cysteine-rich 61 (CYR61) and inflammation was upregulated in the lungs of patients with chronic obstructive pulmonary disease (COPD). However, the association between CYR61 and inflammation was unclear in COPD patients. This study aimed to analyze the association of serum CYR61 with pulmonary inflammation and lung function indexes in COPD patients. Methods: One hundred and fifty COPD patients and 150 control subjects were enrolled. Serum and pulmonary CYR61 was detected. Lung function indexes were evaluated in COPD patients. Results: Serum CYR61 level was elevated and pulmonary CYR61 expression was upregulated in COPD patients. An increased CYR61 was associated with decreased pulmonary function indexes in COPD patients. Further analyses showed that nuclear factor-kappa B (NF-κB) p65-positive nuclei was elevated in the lungs of COPD patients with high level of CYR61. Accordingly, serum monocyte chemotactic protein (MCP)-1 and tumor necrosis factor α (TNF-α), two downstream inflammatory cytokines of NF-κB pathway, were increased in parallel with CYR61, among which serum MCP-1 and TNF-α were the highest in COPD patients with high level of CYR61. Moreover, a positive correlation, determined by multivariate regression that excluded the influence of age, gender and smoking, was observed between serum CYR61 and inflammatory cytokines in COPD patients. Conclusion: These results provide evidence that an increased CYR61 is associated with pulmonary inflammation and COPD progression. Inflammatory cytokines may be the mediators between CYR61 elevation and COPD progression.

Maiwei Yangfei decoction prevents bleomycin-induced pulmonary fibrosis in mice

Maiwei Yangfei (MWYF) is a compound Chinese herb that is safe and effective in the clinical setting in patients with pulmonary fibrosis (PF). The aim of the present study was to assess the role of a (MWYF) decoction in a bleomycin (BLM)-induced PF mouse model and to investigate the underlying functional mechanism. Chemical components within the MWYF decoction were analysed using liquid chromatography-mass spectrometry. A total of 50 C57BL/6 mice were randomly assigned to one of the following five groups with 10 mice per group: Control, model, low dose MWYF (20 g/kg), medium dose MWYF (40 g/kg) and high dose MWYF (60 g/kg). A mouse PF model was established by the tracheal instillation of BLM (5 mg/kg) prior to MWYF treatment, except for mice in the control group. After 21 days of treatment with MWYF, the mice were sacrificed and the body weights were recorded. In addition, pulmonary tissues and bronchial alveolar lavage fluid were collected. TNF-α, IL-6, IL-17, hydroxyproline, pyridinoline and collagen I levels were determined using ELISA. Vimentin, α-smooth muscle actin (α-SMA), fibronectin, TGF-β1, Smad3, TNF-α, IL-6, IL-17, collagen I and collagen III were determined using western blotting. Vimentin and α-SMA levels were also determined using immunofluorescence analysis. Collagens I and III were detected using immunohistochemical analysis and TGF-β1 and Smad3 levels were determined using reverse transcription-quantitative PCR. Following treatment with MWYF decoction, the body weight of the mice in the PF group increased, the degree of pulmonary alveolitis and PF was reduced, collagen levels were reduced and the expression levels of α-SMA, vimentin and fibronectin were decreased. Although both protein and mRNA expression levels of TGF-β1 and Smad3 were reduced, they remained higher than those observed in the control group. To conclude, MWYF decoction delayed the development of BLM-induced PF in mice, where the functional mechanism was likely associated with the TGF-β1/Smad3 signalling pathway.

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

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

The Epithelial-Immune Crosstalk in Pulmonary Fibrosis

Interactions between the lung epithelium and the immune system involve a tight regulation to prevent inappropriate reactions and have been connected to several pulmonary diseases. Although the distal lung epithelium and local immunity have been implicated in the pathogenesis and disease course of idiopathic pulmonary fibrosis (IPF), consequences of their abnormal interplay remain less well known. Recent data suggests a two-way process, as illustrated by the influence of epithelial-derived periplakin on the immune landscape or the effect of macrophage-derived IL-17B on epithelial cells. Additionally, damage associated molecular patterns (DAMPs), released by damaged or dying (epithelial) cells, are augmented in IPF. Next to “sterile inflammation”, pathogen-associated molecular patterns (PAMPs) are increased in IPF and have been linked with lung fibrosis, while outer membrane vesicles from bacteria are able to influence epithelial-macrophage crosstalk. Finally, the advent of high-throughput technologies such as microbiome-sequencing has allowed for the identification of a disease-specific microbial environment. In this review, we propose to discuss how the interplays between the altered distal airway and alveolar epithelium, the lung microbiome and immune cells may shape a pro-fibrotic environment. More specifically, it will highlight DAMPs-PAMPs pathways and the specificities of the IPF lung microbiome while discussing recent elements suggesting abnormal mucosal immunity in pulmonary fibrosis.

Gene therapy strategies for idiopathic pulmonary fibrosis: recent advances, current challenges, and future directions

Idiopathic pulmonary fibrosis (IPF) is a chronic disease in which the lungs become irreversibly scarred, leading to declining lung function. As currently available drugs do not cure IPF, there remains a great medical need for more effective treatments. Perhaps this need could be addressed by gene therapies, which offer powerful and versatile ways to attenuate a wide range of processes involved in fibrosis. Despite the potential benefits of gene therapy, no one has reviewed the current state of knowledge regarding its application for treating IPF. We therefore analyzed publications that reported the use of gene therapies to treat pulmonary fibrosis in animals, as clinical studies have not been published yet. In this review, we first provide an introduction on the pathophysiology of IPF and the most well-established gene therapy approaches. We then present a comprehensive evaluation of published animal studies, after which we provide recommendations for future research to address challenges with respect to the selection and use of animal models as well as the development of delivery vectors and dosage forms. Addressing these considerations will bring gene therapies one step closer to clinical testing and thus closer to patients.

Transient ACE (Angiotensin-Converting Enzyme) Inhibition Suppresses Future Fibrogenic Capacity and Heterogeneity of Cardiac Fibroblast Subpopulations

Transient ACE (angiotensin-converting enzyme) inhibition in spontaneously hypertensive rats is known to protect against future injury-induced cardiac inflammation, fibrosis, and dysfunction; however, the mechanisms of protection have not been delineated. Here, we used single-cell RNA sequencing to test the hypothesis that transient ACE inhibitor treatment would induce a persistent shift in cardiac fibroblast subpopulations. Adult male spontaneously hypertensive rats (11 weeks old, hypertensive with cardiac hypertrophy) were treated for 2 weeks with an ACE inhibitor, enalapril (30 mg/kg per day, PO), or water (untreated spontaneously hypertensive rats) followed by a 2-week washout period (n=7/group). Cardiac fibroblasts were isolated from the left ventricle and subjected to single-cell RNA sequencing. Nine clusters of fibroblasts were identified, with 98% of cells in clusters 0 to 6. The transient treatment produced significant changes both within and across clusters. Cluster 1 depicted a highly fibrogenic gene profile, with cluster 6 serving as a gateway to cluster 1. Transient ACE inhibition depleted the gateway and expanded cluster 0, which was the least fibrogenic profile. Moreover, within cluster 1 fibroblasts, ACE inhibition reduced expression of individual fibrosis genes (eg, COL1A1, COL3A1, and FN1; all P<1×10-35). Clusters 2 to 5 reflected proliferative, moderately fibrogenic, translationally active, and less inflammatory subsets of fibroblasts, all of which exhibited attenuated fibrogenic gene expression after transient ACE inhibition. In conclusion, transient ACE inhibition shifts cardiac fibroblast subpopulations and degree of activation resulting in an overall reduced fibrogenic phenotype.

Nerve Growth Factor (NGF) modulates in vitro induced myofibroblasts by highlighting a differential protein signature

We previously described the profibrogenic effect of NGF on conjunctival Fibroblasts (FBs) and its ability to trigger apoptosis in TGFβ1-induced myofibroblasts (myoFBs). Herein, cell apoptosis/signalling, cytokines' signature in conditioned media and inflammatory as well as angiogenic pathway were investigated. Experimental myoFBs were exposed to NGF (0.1-100 ng/mL), at defined time-point for confocal and biomolecular analysis. Cells were analysed for apoptotic and cell signalling activation in cell extracts and for some inflammatory and proinflammatory/angiogenic factors' activations. NGF triggered cJun overexpression and phospho-p65-NFkB nuclear translocation. A decreased Bcl2:Bax ratio and a significant expression of smad7 were confirmed in early AnnexinV-positive myoFBs. A specific protein signature characterised the conditioned media: a dose dependent decrease occurred for IL8, IL6 while a selective increase was observed for VEGF and cyr61 (protein/mRNA). TIMP1 levels were unaffected. Herein, NGF modulation of smad7, the specific IL8 and IL6 as well as VEGF and cyr61 modulation deserve more attention as opening to alternative approaches to counteract fibrosis.

The role of senescent T cells in immunopathology

The development of senescence in tissues of different organs and in the immune system are usually investigated independently of each other although during ageing, senescence in both cellular systems develop concurrently. Senescent T cells are highly inflammatory and secrete cytotoxic mediators and express natural killer cells receptors (NKR) that bypass their antigen specificity. Instead they recognize stress ligands that are induced by inflammation or infection of different cell types in tissues. In this article we discuss data on T cell senescence, how it is regulated and evidence for novel functional attributes of senescent T cells. We discuss an interactive loop between senescent T cells and senescent non-lymphoid cells and conclude that in situations of intense inflammation, senescent cells may damage healthy tissue. While the example for immunopathology induced by senescent cells that we highlight is cutaneous leishmaniasis, this situation of organ damage may apply to other infections, including COVID-19 and also rheumatoid arthritis, where ageing, inflammation and senescent cells are all part of the same equation.

Emerging role of CCN family proteins in fibrosis

Fibrosis is a common pathological change characterized by the excessive accumulation of fibrous connective tissue. Once uncontrolled, this pathological progress can lead to irreversible damage to the structure and function of organs, which is a serious threat to human health and life. Actually, the disability and death of patients caused by many chronic diseases have a closed relationship with fibrosis. The CCN protein family, including six members, is a small group of matrix proteins exhibiting structurally similar features. In the past 20 years, different biological functions of CCN proteins have been identified in various diseases. Of note, it has been recently shown that they are implicated in the key pathological process of fibrosis. In this review, we summarize the current status of knowledge regarding the role of CCN proteins involved in the pathogenesis of fibrosis diseases in detail. Furthermore, we highlight some of the underlying interaction mechanisms of CCN protein acting in fibrosis that helps to develop new drugs and determine appropriate clinical strategies for fibrotic diseases.

Regulation of cellular senescence by extracellular matrix during chronic fibrotic diseases

The extracellular matrix (ECM) is a complex network of macromolecules surrounding cells providing structural support and stability to tissues. The understanding of the ECM and the diverse roles it plays in development, homoeostasis and injury have greatly advanced in the last three decades. The ECM is crucial for maintaining tissue homoeostasis but also many pathological conditions arise from aberrant matrix remodelling during ageing. Ageing is characterised as functional decline of tissue over time ultimately leading to tissue dysfunction, and is a risk factor in many diseases including cardiovascular disease, diabetes, cancer, dementia, glaucoma, chronic obstructive pulmonary disease (COPD) and fibrosis. ECM changes are recognised as a major driver of aberrant cell responses. Mesenchymal cells in aged tissue show signs of growth arrest and resistance to apoptosis, which are indicative of cellular senescence. It was recently postulated that cellular senescence contributes to the pathogenesis of chronic fibrotic diseases in the heart, kidney, liver and lung. Senescent cells negatively impact tissue regeneration while creating a pro-inflammatory environment as part of the senescence-associated secretory phenotype (SASP) favouring disease progression. In this review, we explore and summarise the current knowledge around how aberrant ECM potentially influences the senescent phenotype in chronic fibrotic diseases. Lastly, we will explore the possibility for interventions in the ECM-senescence regulatory pathways for therapeutic potential in chronic fibrotic diseases.

Somanath P, Zhang D. The Roles of CCN1/CYR61 in Pulmonary Diseases

CCN1 (cysteine-rich 61, connective tissue growth factor, and nephroblastoma-1), previously named CYR61 (cysteine-rich angiogenic inducer 61) belongs to the CCN family of matricellular proteins. CCN1 plays critical roles in the regulation of proliferation, differentiation, apoptosis, angiogenesis, and fibrosis. Recent studies have extensively characterized the important physiological and pathological roles of CCN1 in various tissues and organs. In this review, we summarize both basic and clinical aspects of CCN1 in pulmonary diseases, including acute lung injury (ALI), chronic obstructive pulmonary disease (COPD), lung fibrosis, pulmonary arterial hypertension (PAH), lung infection, and lung cancer. We also emphasize the important challenges for future investigations to better understand the CCN1 and its role in physiology and pathology, as well as the questions that need to be addressed for the therapeutic development of CCN1 antagonists in various lung diseases.

Alveolar CCN1 is associated with mechanical stretch and acute respiratory distress syndrome severity

The cellular communication network factor 1 (CCN1) is a matricellular protein that can modulate multiple tissue responses, including inflammation and repair. We have previously shown that adenoviral overexpression of Ccn1 is sufficient to cause acute lung injury in mice. We hypothesized that CCN1 is present in the airspaces of lungs during the acute phase of lung injury, and higher concentrations are associated with acute respiratory distress syndrome (ARDS) severity. We tested this hypothesis by measuring 1) CCN1 in bronchoalveolar lavage fluid (BALF) and lung homogenates from mice subjected to ventilation-induced lung injury (VILI), 2) Ccn1 gene expression and protein levels in MLE-12 cells (alveolar epithelial cell line) subjected to mechanical stretch, and 3) CCN1 in BALF from mechanically ventilated humans with and without ARDS. BALF CCN1 concentrations and whole lung CCN1 protein levels were significantly increased in mice with VILI (n = 6) versus noninjured controls (n = 6). Ccn1 gene expression and CCN1 protein levels were increased in MLE-12 cells cultured under stretch conditions. Subjects with ARDS (n = 77) had higher BALF CCN1 levels compared with mechanically ventilated subjects without ARDS (n = 45) (P < 0.05). In subjects with ARDS, BALF CCN1 concentrations were associated with higher total protein, sRAGE, and worse [Formula: see text]/[Formula: see text] ratios (all P < 0.05). CCN1 is present in the lungs of mice and humans during the acute inflammatory phase of lung injury, and concentrations are higher in patients with increased markers of severity. Alveolar epithelial cells may be an important source of CCN1 under mechanical stretch conditions.

Conjunction junction, what's the function? CCN proteins as targets in fibrosis and cancers

Cellular communication network (CCN) proteins are matricellular proteins that coordinate signaling among extracellular matrix, secreted proteins, and cell surface receptors. Their specific in vivo function is context-dependent, but they play profound roles in pathological conditions, such as fibrosis and cancers. Anti-CCN therapies are in clinical consideration. Only recently, however, has the function of these complex molecules begun to emerge. This review summarizes and interprets our current knowledge regarding these fascinating molecules and provides experimental evidence for their utility as therapeutic targets.

WISP1 promotes bovine MDSC differentiation via recruitment of ANXA1 for the regulation of the TGF-β signalling pathway

Skeletal muscle is one of the most important tissues of the human body necessary for sporting activities. The differentiation of muscle-derived satellite cells (MDSCs) plays an important role in the development and regeneration of skeletal muscles. Similarly, the Wnt/β-catenin signalling pathway plays an important role in the process of muscle differentiation. Wnt1-inducible signalling pathway protein-1 (WISP1), a downstream protein of the Wnt/β-catenin signalling pathway and a member of the CCN family that also plays an important role in the differentiation process, and its expression increase during the differentiation of bovine MDSCs. However, its role in MDSC differentiation is poorly understood. Therefore, we investigated the mechanisms regulating this process via Western blot and immunofluorescence staining. Immunoprecipitation and mass spectrometry detected annexin A1 (ANXA1), a protein that interacts with WISP1. To determine whether WISP1 influences TGF-β signalling and differentiation independently of ANXA1, the latter was knocked down, while WISP1 was activated. WISP1 expression increased significantly during bovine MDSC differentiation. However, WISP1 did not affect the TGF-β signalling pathway protein marker when ANXA1 was inhibited. Taken together, WISP1 regulates the TGF-β signalling pathway through ANXA1 recruitment, thereby promoting bovine MDSC differentiation, suggesting the Wnt/β-catenin signalling pathway as another target to promote cell differentiation.

Dihydroquercetin protects against renal fibrosis by activating the Nrf2 pathway

BACKGROUND

Dihydroquercetin (DHQ) is an antifibrotic agent. However, whether DHQ can prevent renal fibrosis remains unknown.

PURPOSE

This study aimed to investigate the effects of DHQ on tubulointerstitial fibrosis and its underlying mechanisms in unilateral ureteral obstruction (UUO) mice in vivo and NRK-49F cells in vitro.

METHODS

In vivo, UUO mice received vehicle or DHQ treatment. In vitro, NRK-49F cells were pretreated with DHQ and exposed to transforming growth factor-β1 (TGF-β1). Changes in fibroblast activation, collagen synthesis, oxidative stress, and related signaling pathways were assessed by immunohistochemical staining, Western blot analysis, real-time reverse transcription-PCR, and fluorescence microscopy.

RESULTS

UUO induced tubular atrophy, inflammation, fibroblast differentiation into myofibroblast, and collagen deposition, whereas DHQ ameliorated these effects. UUO also resulted in decreased levels of nuclear factor-erythroid-2-related factor 2 (Nrf2), catalase, and heme oxygenase-1, but increased H₂O₂ and malondialdehyde levels. DHQ treatment corrected these changes. In vitro, the intracellular Nrf2 level of NRK-49F exposed to TGF-β1 decreased. However, DHQ rescued intracellular Nrf2 level and promoted nuclear translocation of Nrf2. DHQ scavenged TGF-β1-induced accumulation of reactive oxygen species, inhibited TGF-β1-induced Smad3 phosphorylation, and prevented TGF-β1-induced fibroblast activation and collagen synthesis in NRK-49F. Nrf2 knockdown could suppress the DHQ-mediated inhibitory effects on oxidative stress, Smad3 phosphorylation, fibroblast activation, and collagen deposition. Furthermore, DHQ ameliorated established renal fibrosis in UUO mice.

CONCLUSIONS

DHQ posed remarkable preventive and therapeutic effects on UUO-induced renal fibrosis and suppressed fibroblast activation by reducing oxidative stress and Smad3 phosphorylation via Nrf2 signaling. This study provided a mechanistic basis for the clinical application of DHQ in renal fibrosis treatment.

Oxidative Stress in Pulmonary Fibrosis

Oxidative stress has been linked to various disease states as well as physiological aging. The lungs are uniquely exposed to a highly oxidizing environment and have evolved several mechanisms to attenuate oxidative stress. Idiopathic pulmonary fibrosis (IPF) is a progressive age-related disorder that leads to architectural remodeling, impaired gas exchange, respiratory failure, and death. In this article, we discuss cellular sources of oxidant production, and antioxidant defenses, both enzymatic and nonenzymatic. We outline the current understanding of the pathogenesis of IPF and how oxidative stress contributes to fibrosis. Further, we link oxidative stress to the biology of aging that involves DNA damage responses, loss of proteostasis, and mitochondrial dysfunction. We discuss the recent findings on the role of reactive oxygen species (ROS) in specific fibrotic processes such as macrophage polarization and immunosenescence, alveolar epithelial cell apoptosis and senescence, myofibroblast differentiation and senescence, and alterations in the acellular extracellular matrix. Finally, we provide an overview of the current preclinical studies and clinical trials targeting oxidative stress in fibrosis and potential new strategies for future therapeutic interventions. © 2020 American Physiological Society. Compr Physiol 10:509-547, 2020.

YAP1 is an independent prognostic marker in pancreatic cancer and associated with extracellular matrix remodeling

Background

Pancreatic cancer is a major cause of cancer-related mortality. The identification of effective biomarkers is essential in order to improve management of the disease. Yes-associated protein 1 (YAP1) is a downstream effector of the Hippo pathway, a signal transduction system implicated in tissue repair and regeneration, as well as tumorigenesis. Here we evaluate the biomarker potential of YAP1 in pancreatic cancer tissue.

Methods

YAP1 was selected as a possible biomarker for pancreatic cancer from global protein sequencing of fresh frozen pancreatic cancer tissue samples and normal pancreas controls. The prognostic utility of YAP1 was evaluated using mRNA expression data from 176 pancreatic cancer patients in The Cancer Genome Atlas (TCGA), as well as protein expression data from immunohistochemistry analysis of a local tissue microarray (TMA) cohort comprising 140 pancreatic cancer patients. Ingenuity Pathway Analysis was applied to outline the interaction network for YAP1 in connection to the pancreatic tumor microenvironment. The expression of YAP1 target gene products was evaluated after treatment of the pancreatic cancer cell line Panc-1 with three substances interrupting YAP–TEAD interaction, including Super-TDU, Verteporfin and CA3.

Results

Mass spectrometry based proteomics showed that YAP1 is the top upregulated protein in pancreatic cancer tissue when compared to normal controls (log2 fold change 6.4; p = 5E−06). Prognostic analysis of YAP1 demonstrated a significant correlation between mRNA expression level data and reduced overall survival (p = 0.001). In addition, TMA and immunohistochemistry analysis suggested that YAP1 protein expression is an independent predictor of poor overall survival [hazard ratio (HR) 1.870, 95% confidence interval (CI) 1.224–2.855, p = 0.004], as well as reduced disease-free survival (HR 1.950, 95% CI 1.299–2.927, p = 0.001). Bioinformatic analyses coupled with in vitro assays indicated that YAP1 is involved in the transcriptional control of target genes, associated with extracellular matrix remodeling, which could be modified by selected substances disrupting the YAP1-TEAD interaction.

Conclusions

Our findings indicate that YAP1 is an important prognostic biomarker for pancreatic cancer and may play a regulatory role in the remodeling of the extracellular matrix.

GPCR-induced YAP activation sensitizes fibroblasts to profibrotic activity of TGFβ1

Tissue fibrosis is a pathological condition characterized by uncontrolled fibroblast activation that ultimately leads to organ failure. The TGFβ1 pathway, one of the major players in establishment of the disease phenotype, is dependent on the transcriptional co-activators YAP/TAZ. We were interested whether fibroblasts can be sensitized to TGFβ1 by activation of the GPCR/YAP/TAZ axis and whether this mechanism explains the profibrotic properties of diverse GPCR ligands. We found that LPA, S1P and thrombin cooperate in human dermal fibroblasts with TGFβ1 to induce extracellular matrix synthesis, myofibroblast marker expression and cytokine secretion. Whole genome expression profiling identified a YAP/TAZ signature behind the synergistic profibrotic effects of LPA and TGFβ1. LPA, S1P and thrombin stimulation led to activation of the Rho-YAP axis, an increase of nuclear YAP-Smad2 complexes and enhanced expression of profibrotic YAP/Smad2-target genes. More generally, dermal, cardiac and lung fibroblast responses to TGFβ1 could be enhanced by increasing YAP nuclear levels (with GPCR ligands LPA, S1P, thrombin or Rho activator) and inhibited by decreasing nuclear YAP (with Rho inhibitor, forskolin, latrunculin B or 2-deoxy-glucose). Thus, we present here a conceptually interesting finding that fibroblast responses to TGFβ1 can be predicted based on the nuclear levels of YAP and modulated by stimuli/treatments that change YAP nuclear levels. Our study contributes to better understanding of fibrosis as a complex interplay of signalling pathways and proposes YAP/TAZ as promising targets in the treatment of fibrosis.

Evasion of apoptosis by myofibroblasts: a hallmark of fibrotic diseases

Organ fibrosis is a lethal outcome of autoimmune rheumatic diseases such as systemic sclerosis. Myofibroblasts are scar-forming cells that are ultimately responsible for the excessive synthesis, deposition and remodelling of extracellular matrix proteins in fibrosis. Advances have been made in our understanding of the mechanisms that keep myofibroblasts in an activated state and control myofibroblast functions. However, the mechanisms that help myofibroblasts to persist in fibrotic tissues remain poorly understood. Myofibroblasts evade apoptosis by activating molecular mechanisms in response to pro-survival biomechanical and growth factor signals from the fibrotic microenvironment, which can ultimately lead to the acquisition of a senescent phenotype. Growing evidence suggests that myofibroblasts and senescent myofibroblasts, rather than being resistant to apoptosis, are actually primed for apoptosis owing to concomitant activation of cell death signalling pathways; these cells are poised to apoptose when survival pathways are inhibited. This knowledge of apoptotic priming has paved the way for new therapies that trigger apoptosis in myofibroblasts by blocking pro-survival mechanisms, target senescent myofibroblast for apoptosis or promote the reprogramming of myofibroblasts into scar-resolving cells. These novel strategies are not only poised to prevent progressive tissue scarring, but also have the potential to reverse established fibrosis and to regenerate chronically injured tissues.

The senescence-associated matricellular protein CCN1 in plasma of human subjects with idiopathic pulmonary fibrosis

INTRODUCTION

Cellular senescence has been linked to the pathogenesis of idiopathic pulmonary fibrosis (IPF). CCN1 is a matricellular protein that has been shown to induce cellular senescence and contribute to lung fibrosis in pre-clinical models. In this report, we determined plasma CCN1 levels in patients with IPF and its potential role in clinical outcomes.

METHODS AND RESULTS

We evaluated 88 patients diagnosed with IPF at the University of Alabama at Birmingham. CCN1 levels were measured in plasma specimens by ELISA. The primary outcome measure was transplant-free survival (TFS) duration. High-CCN1 levels were associated with a lower transplant-free survival independent of %FVC and %D_LCO compared to patients with low plasma CCN1 (HR = 2.15; 95%CI 1.04-4.45, p = 0.04).

CONCLUSION

This study demonstrates that plasma levels of CCN1 may be predictive of survival in IPF. Given the plausible role of CCN1 in cellular senescence and pathobiology of IPF, the predictive value of CCN1 in disease progression among patients with IPF warrants further investigation.

Targeting oxidative stress, proinflammatory cytokines, apoptosis and toll like receptor 4 by empagliflozin to ameliorate bleomycin-induced lung fibrosis

Lung fibrosis is one of the serious complications of bleomycin use in cancer therapy. The aim of this study was to investigate the effect of pre-treatment versus post-treatment with empagliflozin on pulmonary fibrosis induced by bleomycin. One hundred male C57BL/6 mice were divided into 5 equal groups as follows: control group; bleomycin group; bleomycin + carboxymethyl cellulose group; bleomycin group pretreated with empagliflozin and a group treated with empagliflozin after 15 days from starting bleomycin injection. The survival rate, lung weight/body weight ratio, lung tissue hydroxyproline, malondialdehyde, glutathione reductase, superoxide dismutase, nuclear factor (Erythroid-derived 2)-like 2 (Nrf2), heme oxygenase-1 (HO-1) and toll-like receptor 4 (TLR4) were assessed. Also, bronchoalveolar lavage fluid (BALF) was analyzed for total and differential leucocytic count, lactate dehydrogenase, interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α) and transforming growth factor-beta 1 (TGF-β1). The pulmonary tissues were subjected to histopathological, immunohistochemical and electron microscopic study. Empagliflozin induced significant decrease in lung weight/body weight ratio, BALF lactate dehydrogenase, total leucocytic count, IL-6, TNF-α, TLR4 and TGF-β1 associated with significant decrease in lung tissue oxidative stress and hydroxyproline and significant increase in the survival rate and tissue Nrf2/HO-1 content compared to bleomycin group. This was accompanied with significant improvement of the histopathological, immunohistochemical and electron microscopic picture compared to bleomycin group. These effects were significant in mice pretreated with empagliflozin compared to the group that received empagliflozin 15 days after starting bleomycin injection. In conclusion, empagliflozin may be used prophylactically to prevent pulmonary fibrosis induced by bleomycin.

Role of fibroblast growth factor 23 and klotho cross talk in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive fibrosing interstitial pneumonia that mainly affects the elderly. Several reports have demonstrated that aging is involved in the underlying pathogenic mechanisms of IPF. α-Klotho (KL) has been well characterized as an "age-suppressing" hormone and can provide protection against cellular senescence and oxidative stress. In this study, KL levels were assessed in human plasma and primary lung fibroblasts from patients with idiopathic pulmonary fibrosis (IPF-FB) and in lung tissue from mice exposed to bleomycin, which showed significant downregulation when compared with controls. Conversely, transgenic mice overexpressing KL were protected against bleomycin-induced lung fibrosis. Treatment of human lung fibroblasts with recombinant KL alone was not sufficient to inhibit transforming growth factor-β (TGF-β)-induced collagen deposition and inflammatory marker expression. Interestingly, fibroblast growth factor 23 (FGF23), a proinflammatory circulating protein for which KL is a coreceptor, was upregulated in IPF and bleomycin lungs. To our surprise, FGF23 and KL coadministration led to a significant reduction in fibrosis and inflammation in IPF-FB; FGF23 administration alone or in combination with KL stimulated KL upregulation. We conclude that in IPF downregulation of KL may contribute to fibrosis and inflammation and FGF23 may act as a compensatory antifibrotic and anti-inflammatory mediator via inhibition of TGF-β signaling. Upon restoration of KL levels, the combination of FGF23 and KL leads to resolution of inflammation and fibrosis. Altogether, these data provide novel insight into the FGF23/KL axis and its antifibrotic/anti-inflammatory properties, which opens new avenues for potential therapies in aging-related diseases like IPF.

Identification of Cysteine-Rich Angiogenic Inducer 61 as a Potential Antifibrotic and Proangiogenic Mediator in Scleroderma

OBJECTIVE

We previously identified CYR61 as a histone deacetylase 5 (HDAC-5)-repressed gene in systemic sclerosis (SSc; scleroderma) endothelial cells (ECs). When overexpressed, cysteine-rich angiogenic inducer 61 (CYR-61) promoted angiogenesis in SSc ECs. This study was undertaken to examine the role of CYR-61 in fibrosis and determine the mechanisms involved in CYR-61-mediated angiogenesis in SSc.

METHODS

Dermal ECs and fibroblasts were isolated from biopsy specimens from healthy subjects and patients with SSc. CYR-61 level was determined by quantitative polymerase chain reaction, Western blotting, and enzyme-linked immunosorbent assay. CYR-61 was overexpressed using a CYR61 vector or knocked down using small interfering RNA, and functional and mechanistic studies were then conducted in fibroblasts and ECs.

RESULTS

Lower CYR61 messenger RNA levels were observed in dermal fibroblasts and ECs from SSc patients than in those from healthy controls. In SSc fibroblasts, overexpression of CYR-61 led to significant reduction in the expression of profibrotic genes, including COL1A1 (P = 0.002) and ACTA2 (P = 0.04), and an increase in the expression of matrix-degrading genes, including MMP1 (P = 0.002) and MMP3 (P =0.004), and proangiogenic VEGF (P = 0.03). The antifibrotic effect of CYR-61 was further demonstrated by delay in wound healing, inhibition of gel contraction, inactivation of the transforming growth factor β pathway, and early superoxide production associated with senescence in SSc fibroblasts. In SSc ECs, overexpression of CYR-61 led to increased production of vascular endothelial cell growth factor. The proangiogenic effects of CYR-61 were mediated by signaling through αvβ3 receptors and downstream activation of AMP-activated protein kinase, AKT, and the endothelial cell nitric oxide synthase/nitric oxide pathway system.

CONCLUSION

CYR-61, which is epigenetically regulated by HDAC-5, is a potent antifibrotic and proangiogenic mediator in SSc. Therapeutic intervention to promote CYR-61 activity or increase CYR-61 levels might be of benefit in SSc.

Yin/Yang expression of CCN family members: Transforming growth factor beta 1, via ALK5/FAK/MEK, induces CCN1 and CCN2, yet suppresses CCN3, expression in human dermal fibroblasts

The role of the microenvironment in driving connective tissue disease is being increasingly appreciated. Matricellular proteins of the CCN family are signaling modifiers that are secreted by cells into the extracellular matrix microenvironment where they have profound, context-dependent effects on organ development, homeostasis and disease. Indeed, CCN proteins are emergent targets for therapeutic intervention. Recent evidence suggests that, in vivo, CCN3 has effects opposing CCN2. Moreover, when CCN3 expression is high, CCN2 expression is low. That is, they appear to be regulated in a yin/yang fashion, leading to the hypothesis that the CCN2:CCN3 ratio is important to control tissue homeostasis. To begin to test the hypothesis that alterations in CCN2:CCN3 expression might be important in skin biology in vivo, we evaluated the relative ex vivo effects of the profibrotic protein TGFbeta1 on dermal fibroblasts on protein and RNA expression of CCN3 and CCN2, as well as the related protein CCN1. We also used signal transduction inhibitors to begin to identify the signal transduction pathways controlling the ability of fibroblasts to respond to TGFbeta1. As anticipated, CCN1 and CCN2 protein and mRNA were induced by TGFbeta1 in human dermal fibroblasts. This induction was blocked by TAK1, FAK, YAP1 and MEK inhibition. Conversely, TGFbeta1 suppressed CCN3 mRNA expression in a fashion insensitive to FAK, MEK, TAK1 or YAP1 inhibition. Unexpectedly, CCN3 protein was not detected in human dermal fibroblasts basally. These data suggest that, in dermal fibroblasts, the profibrotic protein TGFbeta1 has a divergent effect on CCN3 relative to CCN2 and CCN1, both at the mRNA and protein level. Given that the major source in skin in vivo of CCN proteins are fibroblasts, our data are consistent that alterations in CCN2/CCN1: CCN3 ratios in response to profibrotic agents such as TGFbeta1 may play a role in connective tissue pathologies including fibrosis.

Quantitative proteomic profiling of extracellular matrix and site-specific collagen post-translational modifications in an in vitro model of lung fibrosis

Lung fibrosis is characterized by excessive deposition of extracellular matrix (ECM), in particular collagens, by fibroblasts in the interstitium. Transforming growth factor-β1 (TGF-β1) alters the expression of many extracellular matrix (ECM) components produced by fibroblasts, but such changes in ECM composition as well as modulation of collagen post-translational modification (PTM) levels have not been comprehensively investigated. Here, we performed mass spectrometry (MS)-based proteomics analyses to assess changes in the ECM deposited by cultured lung fibroblasts from idiopathic pulmonary fibrosis (IPF) patients upon stimulation with transforming growth factor β1 (TGF-β1). In addition to the ECM changes commonly associated with lung fibrosis, MS-based label-free quantification revealed profound effects on enzymes involved in ECM crosslinking and turnover as well as multiple positive and negative feedback mechanisms of TGF-β1 signaling. Notably, the ECM changes observed in this in vitro model correlated significantly with ECM changes observed in patient samples. Because collagens are subject to multiple PTMs with major implications in disease, we implemented a new bioinformatic platform to analyze MS data that allows for the comprehensive mapping and site-specific quantitation of collagen PTMs in crude ECM preparations. These analyses yielded a comprehensive map of prolyl and lysyl hydroxylations as well as lysyl glycosylations for 15 collagen chains. In addition, site-specific PTM analysis revealed novel sites of prolyl-3-hydroxylation and lysyl glycosylation in type I collagen. Interestingly, the results show, for the first time, that TGF-β1 can modulate prolyl-3-hydroxylation and glycosylation in a site-specific manner. Taken together, this proof of concept study not only reveals unanticipated TGF-β1 mediated regulation of collagen PTMs and other ECM components but also lays the foundation for dissecting their key roles in health and disease.

The proteomic data has been deposited to the ProteomeXchange Consortium via the MassIVE partner repository with the data set identifier MSV000082958.

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Quantitative proteomics of TGF-β-induced changes in ECM composition and collagen PTM in pulmonary fibroblasts

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TGF-β promotes crosslinking and turnover as well as complex feedback mechanisms that alter fibroblast ECM homeostasis.

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A novel bioinformatic workflow for MS data analysis enabled global mapping and quantitation of known and novel collagen PTMs

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Quantitative assessment of prolyl-3-hydroxylation site occupancy and lysine-O-glycosylation microheterogeneity

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TGF-β1 modulates collagen PTMs in a site-specific manner that may favor collagen accumulation in lung fibrosis

Bioinformatic analysis of next‑generation sequencing data to identify dysregulated genes in fibroblasts of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a lethal fibrotic lung disease with an increasing global burden. It is hypothesized that fibroblasts have a number of functions that may affect the development and progression of IPF. However, the present understanding of cellular and molecular mechanisms associated with fibroblasts in IPF remains limited. The present study aimed to identify the dysregulated genes in IPF fibroblasts, elucidate their functions and explore potential microRNA (miRNA)-mRNA interactions. mRNA and miRNA expression profiles were obtained from IPF fibroblasts and normal lung fibroblasts using a next-generation sequencing platform, and bioinformatic analyses were performed in a step-wise manner. A total of 42 dysregulated genes (>2 fold-change of expression) were identified, of which 5 were verified in the Gene Expression Omnibus (GEO) database analysis, including the upregulation of neurotrimin (NTM), paired box 8 (PAX8) and mesoderm development LRP chaperone, and the downregulation of ITPR interacting domain containing 2 and Inka box actin regulator 2 (INKA2). Previous data indicated that PAX8 and INKA2 serve roles in cell growth, proliferation and survival. Gene Ontology analysis indicated that the most significant function of these 42 dysregulated genes was associated with the composition and function of the extracellular matrix (ECM). A total of 60 dysregulated miRNAs were also identified, and 1,908 targets were predicted by the miRmap database. The integrated analysis of mRNA and miRNA expression data, combined with GEO verification, finally identified Homo sapiens (hsa)-miR-1254-INKA2 and hsa-miR-766-3p-INKA2 as the potential miRNA-mRNA interactions in IPF fibroblasts. In summary, the results of the present study suggest that dysregulation of PAX8, hsa-miR-1254-INKA2 and hsa-miR-766-3p-INKA2 may promote the proliferation and survival of IPF fibroblasts. In the functional analysis of the dysregulated genes, a marked association between fibroblasts and the ECM was identified. These data improve the current understanding of fibroblasts as key cells in the pathogenesis of IPF. As a screening study using bioinformatics approaches, the results of the present study require additional validation.

HDAC8 inhibition ameliorates pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fibroproliferative lung disease, and fibroblast-myofibroblast differentiation (FMD) is thought to be a key event in the pathogenesis of IPF. Histone deacetylase-8 (HDAC8) has been shown to associate with α-smooth muscle actin (α-SMA; a marker of FMD) and regulates cell contractility in vascular smooth muscle cells. However, the role of HDAC8 in FMD or pulmonary fibrosis has never been reported. This study investigated the role of HDAC8 in pulmonary fibrosis with a focus on FMD. We observed that HDAC8 expression was increased in IPF lung tissue as well as transforming growth factor (TGF)β1-treated normal human lung fibroblasts (NHLFs). Immunoprecipitation experiments revealed that HDAC8 was associated with α-SMA in TGFβ1-treated NHLFs. HDAC8 inhibition with NCC170 (HDAC8-selective inhibitor) repressed TGFβ1-induced fibroblast contraction and α-SMA protein expression in NHLFs cultured in collagen gels. HDAC8 inhibition with HDAC8 siRNA also repressed TGFβ1-induced expression of profibrotic molecules such as fibronectin and increased expression of antifibrotic molecules such as peroxisome proliferator-activated receptor-γ (PPARγ). Chromatin immunoprecipitation quantitative PCR using an antibody against H3K27ac (histone H3 acetylated at lysine 27; a known HDAC8 substrate and a marker for active enhancers) suggested that HDAC8 inhibition with NCC170 ameliorated TGFβ1-induced loss of H3K27ac at the PPARγ gene enhancer. Furthermore, NCC170 treatment significantly decreased fibrosis measured by Ashcroft score as well as expression of type 1 collagen and fibronectin in bleomycin-treated mouse lungs. These data suggest that HDAC8 contributes to pulmonary fibrosis and that there is a therapeutic potential for HDAC8 inhibitors to treat IPF as well as other fibrotic lung diseases.

Targeted matrisome analysis identifies thrombospondin-2 and tenascin-C in aligned collagen stroma from invasive breast carcinoma

Increasing evidence demonstrates an important role for the extracellular matrix (ECM) in breast cancer progression. Collagen type I, a core constituent of the fibrous ECM, undergoes a significant set of changes that accompany tumor progression, termed Tumor Associated Collagen Signatures (TACS). Late stages of this progression are characterized by the presence of bundled, straight collagen (TACS-2) that become oriented perpendicular to the tumor-stromal boundary (TACS-3). Importantly, the presence of TACS-3 collagen is an independent predictor of poor patient outcome. At present, it remains unclear whether reorganization of the collagen matrix is the consequence of mechanical or compositional tissue remodeling. Here, we identify compositional changes in ECM correlating to collagen fiber reorganization from nineteen normal and invasive ductal carcinoma (IDC) patient biopsies using matrisome-targeted proteomics. Twenty-seven ECM proteins were significantly altered in IDC samples compared to normal tissue. Further, a set of nineteen matrisome proteins positively correlate and five proteins inversely correlate with IDC tissues containing straightened collagen fibers. Tenascin-C and thrombospondin-2 significantly co-localized with aligned collagen fibers in IDC tissues. This study highlights the compositional change in matrisome proteins accompanying collagen re-organization during breast cancer progression and provides candidate proteins for investigation into cellular and structural influences on collagen alignment.

Aucubin Alleviates Bleomycin-Induced Pulmonary Fibrosis in a Mouse Model

Pulmonary fibrosis is a life-threatening disease characterized by progressive dyspnea and worsening of pulmonary function. No effective therapeutic strategy for pulmonary fibrosis has been established. Aucubin is a natural constituent with a monoterpene cyclic ring system. The potency of aucubin in protecting cellular components against inflammation, oxidative stress, and proliferation effects is well documented. In this study, we investigated the protective effect of aucubin against pulmonary fibrosis in mice. A mouse model of pulmonary fibrosis was established by intratracheal injection of bleomycin (BLM), and aucubin was administered for 21 days after BLM injection. We found that aucubin decreased the breathing frequency and increased the lung dynamic compliance of BLM-stimulated mice detected by Buxco pulmonary function testing system. Histological examination showed that aucubin alleviated BLM-induced lung parenchymal fibrotic changes. Aucubin also reduced the intrapulmonary collagen disposition and inflammatory injury induced by BLM. In addition, aucubin reduced the expression of pro-fibrotic protein transforming growth factor (TGF)-β1 and α-smooth muscle actin (α-SMA) of pulmonary fibrosis mice induced by BLM. Furthermore, the effect of aucubin on the proliferation and differentiation of fibroblast was investigated in vitro. Aucubin inhibited the mRNA and protein expression of Ki67 and proliferating cell nuclear antigen (PCNA) induced by TGF-β1 and reduced the cell proliferation in a murine fibroblast cell NIH3T3. Aucubin also reduced the collagen syntheses and α-SMA expression induced by TGF-β1 in fibroblast. Our results indicate that aucubin inhibits inflammation, fibroblast proliferation, and differentiation, exerting protective effects against BLM-induced pulmonary fibrosis in a mouse model. This study provides an evidence that aucubin may be a novel drug for pulmonary fibrosis.

Cell-surface phenotyping identifies CD36 and CD97 as novel markers of fibroblast quiescence in lung fibrosis

Fibroblasts play an important role in lung homeostasis and disease. In lung fibrosis, fibroblasts adopt a proliferative and migratory phenotype, with increased expression of α-smooth muscle actin (αSMA) and enhanced secretion of extracellular matrix components. Comprehensive profiling of fibroblast heterogeneity is limited because of a lack of specific cell-surface markers. We have previously profiled the surface proteome of primary human lung fibroblasts. Here, we sought to define and quantify a panel of cluster of differentiation (CD) markers in primary human lung fibroblasts and idiopathic pulmonary fibrosis (IPF) lung tissue, using immunofluorescence and FACS analysis. Fibroblast function was assessed by analysis of replicative senescence. We observed the presence of distinct fibroblast phenotypes in vivo, characterized by various combinations of Desmin, αSMA, CD36, or CD97 expression. Most markers demonstrated stable expression over passages in vitro, but significant changes were observed for CD36, CD54, CD82, CD106, and CD140a. Replicative senescence of fibroblasts was observed from passage 10 onward. CD36- and CD97-positive but αSMA-negative cells were present in remodeled areas of IPF lungs. Transforming growth factor (TGF)-β treatment induced αSMA and collagen I expression but repressed CD36 and CD97 expression. We identified a panel of stable surface markers in human lung fibroblasts, applicable for positive-cell isolation directly from lung tissue. TGF-β exposure represses CD36 and CD97 expression, despite increasing αSMA expression; we therefore identified complex surface protein changes during fibroblast-myofibroblast activation. Coexistence of quiescence and activated fibroblast subtypes in the IPF lung suggests dynamic remodeling of fibroblast activation upon subtle changes to growth factor exposure in local microenvironmental niches.

The matricellular protein CCN1 in tissue injury repair

The expression of Ccn1 (Cyr61) is essential for cardiovascular development during embryogenesis, whereas in adulthood it is associated with inflammation, wound healing, injury repair, and related pathologies including fibrosis and cancer. Recent studies have found that CCN1 plays a critical role in promoting wound healing and tissue repair. Mechanistically, CCN1 functions through direct interaction with specific integrin receptors expressed in various cell types in the wound tissue microenvironment to coordinate diverse cellular functions for repair. Here we briefly summarize the current knowledge on the functions of CCN1 in tissue injury repair and discuss pertinent unanswered questions.