Recent developments in myofibroblast biology: paradigms for connective tissue remodeling

Noncanonical Wnt Signaling Promotes Myofibroblast Differentiation in Pulmonary Fibrosis

The Wnt/β-catenin pathway initiates a signaling cascade that is critical in cell differentiation and the normal development of multiple organ systems. The reactivation of this pathway has been documented in experimental and human idiopathic pulmonary fibrosis, wherein Wnt/β-catenin activation has been implicated in epithelial-cell repair. Furthermore, the canonical ligand Wnt3a is known to induce myofibroblast differentiation; however, the role of noncanonical Wnt ligands remains unclear. This study showed significantly higher levels of Wnt11 expression in cells from both patients with idiopathic pulmonary fibrosis and bleomycin-treated mice, as well as in TGFβ-treated mouse lung fibroblasts. Moreover, Wnt11 induced myofibroblast differentiation as manifested by increased α-SMA (ACTA2) expression, which was similar to that induced by canonical Wnt3a/β-catenin signaling. Further investigation revealed that Wnt11 induction of α-SMA was associated with the activation of JNK (c-Jun N-terminal kinase)/c-Jun signaling and was inhibited by a JNK inhibitor. The potential importance of this signaling pathway was supported by in vivo evidence showing significantly increased levels of Wnt11 and activated JNK in the lungs of mice with bleomycin-induced pulmonary fibrosis. Interestingly, fibroblasts did not express canonical Wnt3a, but treatment of these cells with exogenous Wnt3a induced endogenous Wnt11 and Wnt5a, resulting in repression of the Wnt3a/β-catenin target gene Axin2. These findings suggested that the noncanonical Wnt induction of myofibroblast differentiation mediated by the JNK/c-Jun pathway might play a significant role in pulmonary fibrosis, in addition to or in synergy with canonical Wnt3a/β-catenin signaling. Moreover, Wnt3a activation of noncanonical Wnt signaling might trigger a switch from canonical to noncanonical Wnt signaling to induce myofibroblast differentiation.

Blood fibrocytes are associated with severity and prognosis in COVID-19 pneumonia

Increased blood fibrocytes are associated with a poor prognosis in fibrotic lung diseases. We aimed to determine whether the percentage of circulating fibrocytes could be predictive of severity and prognosis during coronavirus disease 2019 (COVID-19) pneumonia. Blood fibrocytes were quantified by flow cytometry as CD45⁺/CD15^-/CD34⁺/collagen-1⁺ cells in patients hospitalized for COVID-19 pneumonia. In a subgroup of patients admitted in an intensive care unit (ICU), fibrocytes were quantified in blood and bronchoalveolar lavage (BAL). Serum amyloid P (SAP), transforming growth factor-β1 (TGF-β1), CXCL12, CCL2, and FGF2 concentrations were measured. We included 57 patients in the hospitalized group (median age = 59 yr [23-87]) and 16 individuals as healthy controls. The median percentage of circulating fibrocytes was higher in the patients compared with the controls (3.6% [0.2-9.2] vs. 2.1% [0.9-5.1], P = 0.04). Blood fibrocyte count was lower in the six patients who died compared with the survivors (1.6% [0.2-4.4] vs. 3.7% [0.6-9.2], P = 0.02). Initial fibrocyte count was higher in patients showing a complete lung computed tomography (CT) resolution at 3 mo. Circulating fibrocyte count was decreased in the ICU group (0.8% [0.1-2.0]), whereas BAL fibrocyte count was 6.7% (2.2-15.4). Serum SAP and TGF-β1 concentrations were increased in hospitalized patients. SAP was also increased in ICU patients. CXCL12 and CCL2 were increased in ICU patients and negatively correlated with circulating fibrocyte count. We conclude that circulating fibrocytes were increased in patients hospitalized for COVID-19 pneumonia, and a lower fibrocyte count was associated with an increased risk of death and a slower resolution of lung CT opacities.

Protective effect of dimethyl itaconate against fibroblast-myofibroblast differentiation during pulmonary fibrosis by inhibiting TXNIP

Fibroblast-myofibroblast differentiation (FMD) is a critical cellular phenotype during the occurrence and deterioration of pulmonary fibrosis (PF). FMD can increase with an elevated level of reactive oxygen species (ROS) on fibroblasts under oxidative stress. Thioredoxin-interacting protein (TXNIP) is an α-arrestin family protein that regulates the level of intracellular ROS. Nuclear factor erythroid 2-related factor 2 (Nrf2) can protect against FMD in PF. However, the relationship between Nrf2 and TXNIP in FMD remains elusive. Therefore, we established TGF-β1-induced FMD in vitro and bleomycin (BLM)-induced mouse PF model in vivo to explore whether the activation of Nrf2 can inhibit TXNIP-mediated FMD in PF. Dimethyl itaconate (DMI) was selected to activate Nrf2. Our results showed that TXNIP was elevated and FMD was aggravated in mice lung tissues after BLM administration compared with the saline group. Inversely, Nrf2 decreased TXNIP expression and alleviated FMD in PF. In vitro, TXNIP overexpression enhanced FMD and increased the level of ROS. In contrast, TXNIP deficiency by small interfering RNA (siRNA) attenuated TGF-β1-induced FMD and reduced ROS. An increase in ROS by H2 O2 can upregulate TXNIP expression. Moreover, Nrf2 also inhibited TGF-β1-induced FMD and the increase of ROS, with reducing expression of TXNIP, and the inhibitory effect was better than TXNIP siRNA. These results suggest that activation of Nrf2 by DMI can protect against PF via inhibiting TXNIP expression. Our study may provide new therapeutic targets and treatment approaches for PF.

Asporin Promotes TGF-β-induced Lung Myofibroblast Differentiation by Facilitating Rab11-dependent Recycling of TβRI

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive fibrotic lung disease with high mortality and morbidity. Asporin (ASPN), a member of the small leucine-rich proteoglycan (SLRP) family, plays crucial roles in tissue injury and regeneration. However, the precise pathophysiological role of ASPN and its molecular mechanisms in IPF remain unknown. We sought to investigate the role of ASPN during the development of pulmonary fibrosis and the therapeutic potential of targeting ASPN-related signaling pathways. In our study, three microarray datasets were downloaded from the Gene Expression Omnibus (GEO) database, and differentially expressed genes (DEGs) were screened out by bioinformatic analysis. Hub genes were selected from the protein-protein interaction network. ASPN was examined in lung tissues from pulmonary fibrosis mouse models and the role of ASPN in TGF-β/Smad signaling was determined by transfection with ASPN shRNA vectors in vitro. Biotinylation assays were conducted to measure plasma membrane TβRI and TβRI recycling after ASPN knockdown. The results showed ASPN expression was increased in the lungs of pulmonary fibrosis mouse models, and ASPN was primarily localized in α-SMA+ myofibroblasts. In vitro experiments proved that ASPN knockdown inhibited TGF-β/Smad signaling and myofibroblast differentiation by regulating the stability of TβRI. Further molecular mechanisms revealed that ASPN knockdown inhibited TGF-β/Smad signaling by suppressing recycling of TβRI to the cell surface in a Rab11-dependent manner and facilitated lysosome-mediated degradation of TβRI. In conclusion, our findings provide important evidence for the use of ASPN as a novel pharmacological target for treating pulmonary fibrosis.

Serine-Threonine Kinase inhibition as antifibrotic therapy: TGF-β and ROCK inhibitors

Serine-threonine kinases mediate the phosphorylation of intracellular protein targets, transferring a phosphorus group from an ATP molecule to the specific amino acid residues within the target proteins. Serine-threonine kinases regulate multiple key cellular functions. From this large group of kinases, transforming growth factor beta (TGF-β) through the serine-threonine activity of its receptors and Rho kinase (ROCK) play an important role in the development and maintenance of fibrosis in various human diseases, including systemic sclerosis. In recent years, multiple drugs targeting and inhibiting these kinases, have been developed, opening the possibility of becoming potential antifibrotic agents of clinical value for treating fibrotic diseases. This review analyzes the contribution of TGF- β and ROCK-mediated serine-threonine kinase molecular pathways to the development and maintenance of pathological fibrosis and the potential clinical use of their inhibition.

Global gene expression analysis of systemic sclerosis myofibroblasts demonstrates a marked increase in the expression of multiple NBPF genes

Myofibroblasts are the key effector cells responsible for the exaggerated tissue fibrosis in Systemic Sclerosis (SSc). Despite their importance to SSc pathogenesis, the specific transcriptome of SSc myofibroblasts has not been described. The purpose of this study was to identify transcriptome differences between SSc myofibroblasts and non-myofibroblastic cells. Alpha smooth muscle actin (α-SMA) expressing myofibroblasts and α-SMA negative cells were isolated employing laser capture microdissection from dermal cell cultures from four patients with diffuse SSc of recent onset. Total mRNA was extracted from both cell populations, amplified and analyzed employing microarrays. Results for specific genes were validated by Western blots and by immunohistochemistry. Transcriptome analysis revealed 97 differentially expressed transcripts in SSc myofibroblasts compared with non-myofibroblasts. Annotation clustering of the SSc myofibroblast-specific transcripts failed to show a TGF-β signature. The most represented transcripts corresponded to several different genes from the Neuroblastoma Breakpoint Family (NBPF) of genes. NBPF genes are highly expanded in humans but are not present in murine or rat genomes. In vitro studies employing cultured SSc dermal fibroblasts and immunohistochemistry of affected SSc skin confirmed increased NBPF expression in SSc. These results indicate that SSc myofibroblasts represent a unique cell lineage expressing a specific transcriptome that includes very high levels of transcripts corresponding to numerous NBPF genes. Elevated expression of NBPF genes in SSc myofibroblasts suggests that NBPF gene products may play a role in SSc pathogenesis and may represent a novel therapeutic target.

Adaptations in Hippo-Yap signaling and myofibroblast fate underlie scar-free ear appendage wound healing in spiny mice

Spiny mice (Acomys cahirinus) are terrestrial mammals that evolved unique scar-free regenerative wound-healing properties. Myofibroblasts (MFs) are the major scar-forming cell type in skin. We found that following traumatic injury to ear pinnae, MFs appeared rapidly in both Acomys and mouse yet persisted only in mouse. The timing of MF loss in Acomys correlated with wound closure, blastema differentiation, and nuclear localization of the Hippo pathway target protein Yap. Experiments in vitro revealed an accelerated PP2A-dependent dephosphorylation activity that maintained nuclear Yap in Acomys dermal fibroblasts (DFs) and was not detected in mouse or human DFs. Treatment of Acomys in vivo with the nuclear Yap-TEAD inhibitor verteporfin prolonged MF persistence and converted tissue regeneration to fibrosis. Forced Yap activity prevented and rescued TGF-β1-induced human MF formation in vitro. These results suggest that Acomys evolved modifications of Yap activity and MF fate important for scar-free regenerative wound healing in vivo.

Perspective on Stem Cell Therapy in Organ Fibrosis: Animal Models and Human Studies

Tissue fibrosis is characterized by excessive deposition of extracellular matrix (ECM) components that result from the disruption of regulatory processes responsible for ECM synthesis, deposition, and remodeling. Fibrosis develops in response to a trigger or injury and can occur in nearly all organs of the body. Thus, fibrosis leads to severe pathological conditions that disrupt organ architecture and cause loss of function. It has been estimated that severe fibrotic disorders are responsible for up to one-third of deaths worldwide. Although intensive research on the development of new strategies for fibrosis treatment has been carried out, therapeutic approaches remain limited. Since stem cells, especially mesenchymal stem cells (MSCs), show remarkable self-renewal, differentiation, and immunomodulatory capacity, they have been intensively tested in preclinical studies and clinical trials as a potential tool to slow down the progression of fibrosis and improve the quality of life of patients with fibrotic disorders. In this review, we summarize in vitro studies, preclinical studies performed on animal models of human fibrotic diseases, and recent clinical trials on the efficacy of allogeneic and autologous stem cell applications in severe types of fibrosis that develop in lungs, liver, heart, kidney, uterus, and skin. Although the results of the studies seem to be encouraging, there are many aspects of cell-based therapy, including the cell source, dose, administration route and frequency, timing of delivery, and long-term safety, that remain open areas for future investigation. We also discuss the contemporary status, challenges, and future perspectives of stem cell transplantation for therapeutic options in fibrotic diseases as well as we present recent patents for stem cell-based therapies in organ fibrosis.

Organ Specificity and Heterogeneity of Cancer-Associated Fibroblasts in Colorectal Cancer

Fibroblasts constitute a ubiquitous mesenchymal cell type and produce the extracellular matrix (ECM) of connective tissue, thereby providing the structural basis of various organs. Fibroblasts display differential transcriptional patterns unique to the organ of their origin and they can be activated by common stimuli such as transforming growth factor-β (TGF-β) and platelet-derived growth factor (PDGF) signaling. Cancer-associated fibroblasts (CAFs) reside in the cancer tissue and contribute to cancer progression by influencing cancer cell growth, invasion, angiogenesis and tumor immunity. CAFs impact on the tumor microenvironment by remodeling the ECM and secreting soluble factors such as chemokines and growth factors. Differential expression patterns of molecular markers suggest heterogeneous features of CAFs in terms of their function, pathogenic role and cellular origin. Recent studies elucidated the bimodal action of CAFs on cancer progression and suggest a subgroup of CAFs with tumor-suppressive effects. This review attempts to describe cellular features of colorectal CAFs with an emphasis on their heterogeneity and functional diversity.

Nestin promotes pulmonary fibrosis via facilitating recycling of TGF-β receptor I

Background

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease that is characterised by aberrant proliferation of activated myofibroblasts and pathological remodelling of the extracellular matrix. Previous studies have revealed that the intermediate filament protein nestin plays key roles in tissue regeneration and wound healing in different organs. Whether nestin plays a critical role in the pathogenesis of IPF needs to be clarified.

Methods

Nestin expression in lung tissues from bleomycin-treated mice and IPF patients was determined. Transfection with nestin short hairpin RNA vectors in vitro that regulated transcription growth factor (TGF)-β/Smad signalling was conducted. Biotinylation assays to observe plasma membrane TβRI, TβRI endocytosis and TβRI recycling after nestin knockdown were performed. Adeno-associated virus serotype (AAV)6-mediated nestin knockdown was assessed in vivo.

Results

We found that nestin expression was increased in a murine pulmonary fibrosis model and IPF patients, and that the upregulated protein primarily localised in lung α-smooth muscle actin-positive myofibroblasts. Mechanistically, we determined that nestin knockdown inhibited TGF-β signalling by suppressing recycling of TβRI to the cell surface and that Rab11 was required for the ability of nestin to promote TβRI recycling. In vivo, we found that intratracheal administration of AAV6-mediated nestin knockdown significantly alleviated pulmonary fibrosis in multiple experimental mice models.

Conclusion

Our findings reveal a pro-fibrotic function of nestin partially through facilitating Rab11-dependent recycling of TβRI and shed new light on pulmonary fibrosis treatment.

Nestin regulates the vesicular trafficking system by promoting Rab11-dependent recycling of TβRI and thereby contributes to the progression of pulmonary fibrosis. Precise targeting of nestin may represent a potential therapeutic strategy for IPF.https://bit.ly/3zO75c3

Anlotinib Inhibits PFKFB3-Driven Glycolysis in Myofibroblasts to Reverse Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal disease in which the normal alveolar network is gradually replaced by fibrotic scars. Current evidence suggests that metabolic alterations correlate with myofibroblast activation in IPF. Anlotinib has been proposed to have antifibrotic effects, but the efficacy and mechanisms of anlotinib against lung fibrosis have not been systematically evaluated. The antifibrotic effects of anlotinib were evaluated in bleomycin-induced mouse models and transforming growth factor-beta 1 (TGF-β1)-stimulated lung fibroblasts. We measured lactate levels, 2-NBDG glucose uptake and the extracellular acidification rate (ECAR) to assess glycolysis in fibroblasts. RNA-protein coimmunoprecipitation (RIP) and polysome analyses were performed to investigate novel mechanisms of glycolytic reprogramming in pulmonary fibrosis. We found that anlotinib diminished myofibroblast activation and inhibited the augmentation of glycolysis. Moreover, we show that PCBP3 posttranscriptionally increases PFKFB3 expression by promoting its translation during myofibroblast activation, thus promoting glycolysis in myofibroblasts. Regarding mechanism, anlotinib exerts potent antifibrotic effects by downregulating PCBP3, reducing PFKFB3 translation and inhibiting glycolysis in myofibroblasts. Furthermore, we observed that anlotinib had preventative and therapeutic antifibrotic effects on bleomycin-induced pulmonary fibrosis. Therefore, we identify PCBP3 as a protein involved in the regulation of glycolysis reprogramming and lung fibrogenesis and propose it as a therapeutic target for pulmonary fibrosis. Our data suggest that anlotinib has antifibrotic effects on the lungs, and we provide a novel mechanism for this effect. Anlotinib may constitute a novel and potent candidate for the treatment of pulmonary fibrosis.

Integrated 3D Printing-Based Framework-A Strategy to Fabricate Tubular Structures with Mechanocompromised Hydrogels

Several hollow organs perform various crucial functions in the body and must be replaced, repaired, or augmented in many disease conditions. Fabrication of tissue analogues to these hollow organs is incredibly challenging. Still, recent advancements in biofabrication have allowed researchers to pursue the development of several hollow organs such as blood vessels, esophagus, trachea, urethra, and others. Materials like collagen, alginate, elastin, silk, fibrin, etc., have been predominantly used for organ development. However, the focus has been duly shifted toward decellularized extracellular matrix (dECM) to develop tissue-specific hydrogels because they provide relevant biochemical cues to promote cellular activity. Still, the dECM-based hydrogels are mechanically weak to fabricate self-supporting tubular structures. Here, an innovative approach using the stereolithography apparatus (SLA) 3D printed framework has been implemented to achieve a self-supporting tubular structure using caprine esophagus muscle dECM hydrogel. A significant improvement in the mechanical stability of the biofabricated tissue has been observed within 7 days of culture. Interestingly, the encapsulated L929 mouse fibroblasts transdifferentiated into myofibroblasts because of the cues provided by the muscle dECM. Overall, the potential of an SLA-based 3D printing strategy to fabricate frameworks, especially for fabricating tubular organs/tissues using mechanocompromised hydrogel, has been demonstrated here.

Application of ADSCs and their Exosomes in Scar Prevention

Scar is a common way of healing after tissue injury. The poor scar healing will not only cause dysfunction of tissues and organs but also affect the appearance of the patients’ body surface, which causes the pressure of life and spirit to the patients. However, the formation of scar tissue is an extremely complex process and its mechanism is not fully understood. At present, there is no treatment method to eliminate scars completely. Fibroblasts are the most abundant cells in the dermis, which have the ability to synthesize and remodel extracellular matrix (ECM). Myofibroblasts actively participate in the wound healing process and influence the outcome. Therefore, both of them play important roles in wound healing and scar formation. Adipose tissue-derived stem cells (ADSCs) are pluripotent stem cells that can act on target cells by paracrine. Adipose tissue stem cell-derived exosomes (ADSC-Exos) are important secretory substances of ADSCs. They are nanomembrane vesicles that can transport a variety of cellular components and fuse with target cells. In this review, we will discuss the effects of ADSCs and ADSC-Exos on the behavior of fibroblasts and myofibroblasts during wound healing and scarring stage in combination with recent studies.

Engrailed 1 coordinates cytoskeletal reorganization to induce myofibroblast differentiation

Transforming growth factor-β (TGFβ) is a key mediator of fibroblast activation in fibrotic diseases, including systemic sclerosis. Here we show that Engrailed 1 (EN1) is reexpressed in multiple fibroblast subpopulations in the skin of SSc patients. We characterize EN1 as a molecular amplifier of TGFβ signaling in myofibroblast differentiation: TGFβ induces EN1 expression in a SMAD3-dependent manner, and in turn, EN1 mediates the profibrotic effects of TGFβ. RNA sequencing demonstrates that EN1 induces a profibrotic gene expression profile functionally related to cytoskeleton organization and ROCK activation. EN1 regulates gene expression by modulating the activity of SP1 and other SP transcription factors, as confirmed by ChIP-seq experiments for EN1 and SP1. Functional experiments confirm the coordinating role of EN1 on ROCK activity and the reorganization of cytoskeleton during myofibroblast differentiation, in both standard fibroblast culture systems and in vitro skin models. Consistently, mice with fibroblast-specific knockout of En1 demonstrate impaired fibroblast-to-myofibroblast transition and are partially protected from experimental skin fibrosis.

Current Concepts on the Pathogenesis of Systemic Sclerosis

From the clinical standpoint, systemic sclerosis (SSc) is characterized by skin and internal organ fibrosis, diffuse fibroproliferative vascular modifications, and autoimmunity. Clinical presentation and course are highly heterogenous and life expectancy variably affected mostly dependent on lung and heart involvement. SSc touches more women than men with differences in disease severity and environmental exposure. Pathogenetic events originate from altered homeostasis favored by genetic predisposition, environmental cues and a variety of endogenous and exogenous triggers. Epigenetic modifications modulate SSc pathogenesis which strikingly associate profound immune-inflammatory dysregulation, abnormal endothelial cell behavior, and cell trans-differentiation into myofibroblasts. SSc myofibroblasts show enhanced survival and enhanced extracellular matrix deposition presenting altered structure and altered physicochemical properties. Additional cell types of likely pathogenic importance are pericytes, platelets, and keratinocytes in conjunction with their relationship with vessel wall cells and fibroblasts. In SSc, the profibrotic milieu is favored by cell signaling initiated in the one hand by transforming growth factor-beta and related cytokines and in the other hand by innate and adaptive type 2 immune responses. Radical oxygen species and invariant receptors sensing danger participate to altered cell behavior. Conventional and SSc-specific T cell subsets modulate both fibroblasts as well as endothelial cell dysfunction. Beside autoantibodies directed against ubiquitous antigens important for enhanced clinical classification, antigen-specific agonistic autoantibodies may have a pathogenic role. Recent studies based on single-cell RNAseq and multi-omics approaches are revealing unforeseen heterogeneity in SSc cell differentiation and functional states. Advances in system biology applied to the wealth of data generated by unbiased screening are allowing to subgroup patients based on distinct pathogenic mechanisms. Deciphering heterogeneity in pathogenic mechanisms will pave the way to highly needed personalized therapeutic approaches.

CircRNA_0026344 via exosomal miR-21 regulation of Smad7 is involved in aberrant cross-talk of epithelium-fibroblasts during cigarette smoke-induced pulmonary fibrosis

For smoking-induced pulmonary fibrosis (PF), a serious disease endangering human health, there is no effective clinical treatment. Aberrant epithelium-fibroblast cross-talk is involved in formation of the excessive extracellular matrix (ECM) that contributes to PF. Circular RNAs have been associated with various pulmonary diseases. However, the mechanisms of circRNAs in PF are not clear. Herein, our goals were to investigate the involvement of circRNA_0026344 in the aberrant epithelium-fibroblast cross-talk induced by cigarette smoke (CS) and to define its mechanism. Chronic exposure (16 weeks) of BALB/c mice to 500 mg/m3 CS induced lung injury and fibrosis in lung tissues. From HBE cells, circRNA_0026344 was selected by microarray analysis and verified as that with the most severe down-regulation caused by cigarette smoke extract (CSE). The regulatory relationship between circRNA_0026344 and miR-21 was assessed by use of bioinformatics, RNA pull-down assays, and qRT-PCR. We found that miR-21 binding sites were present in circRNA_0026344 and, in HBE cells, it could act as a sponge for miR-21. When pcDNA3.0-circRNA_0026344, a high expression plasmid of circRNA_0026344, was transfected into HBE cells, the CSE-induced up-regulation of miR-21 levels was reversed. In MRC-5 cells, HBE-secreted exosomal miR-21 decreased levels of Smad7 and activated the TGF-β1/Smad3 pathway. By using the Targetscan database, the presence of species-conserved miR-21 binding sites in the Smad7 3'UTR region were predicted. We verified, by use of a luciferase reporter gene, that miR-21 bound to the 3'UTR region of Smad7 mRNA to inhibit its transcription. In conclusion, the results reveal that, in CS-induced pulmonary fibrosis, circRNA_0026344, via exosomal miR-21 regulation of Smad7, is involved in aberrant cross-talk of epithelium-fibroblasts. These results will be useful for the discovery of early biomarkers and for providing therapeutic targets for smoking-induced pulmonary fibrosis.

Expression of NF-κB-p65 and α-SMA in the Study of Capsules formed by Surface Textured Implants Versus Foam Covered Silicone Implants in a Rat Model

BACKGROUND

We aimed to compare inflammatory and intercellular transcription responses induced by surface textured (ST) implants versus foam covered (FC) silicone implants placed on the dorsal aspect of rats.

METHODS

We utilized 80 female rats of the Wistar lineage. The rats were divided into four subgroups of 20 with one type of implant placed in the dorsum per rat. Analysis was carried out on peri-implant capsules at 90 d and at 180 d post-surgery with microscopic evaluation of inflammatory and immuno-histochemical response of NF-κB-p65 and α-SMA in fibroblasts. This study was carried out at the Evangelical Faculty of Parana and at the Ivo Pitanguy Institute, Brazil in 2015.

RESULTS

The FC exhibited higher levels of acute and chronic inflammation on evaluation in both time frames. The capsule surrounding the ST implants was significantly thicker with well-organized collagen fibres. NFκB-p65 expression in the capsule surrounding the FC implant was more pronounced. There was higher and more significant α-SMA expression in the capsules of the surface textured (ST) silicone implants compared to the foam-covered (FC) silicone implants.

CONCLUSION

Activation of NFκB-p65 plays a key role in the evolution of capsule formation and maintenance of inflammation by regulating the healing process. Similarly, higher and more prolonged levels of inflammation (increased NF-κB-p65 results in increased inflammation) and lower α-SMA (higher α-SMA is protective against capsular contracture) did not directly translate to a thicker capsule and ultimately, capsular contracture in foam covered silicone implants.

Benzalkonium chloride-induced myofibroblastic transdifferentiation of Tenon's capsule fibroblasts is inhibited by coculture with corneal epithelial cells or by interleukin-10

Benzalkonium chloride (BAC) is used as a preservative in eyedrops but induces subconjunctival fibrosis that can result in failure of glaucoma surgery. Tenon's capsule fibroblasts in subconjunctival tissue interact with the corneal epithelium through tear fluid. With the use of a coculture system, we have now investigated the effect of human corneal epithelial (HCE) cells on myofibroblastic transdifferentiation of human Tenon fibroblasts (HTFs) induced by BAC (5 × 10^-6%). Immunofluorescence and immunoblot analyses revealed that the BAC-induced expression of α smooth muscle actin (αSMA) in HTFs was suppressed by coculture of these cells with HCE cells (p < 0.01). The concentration of interleukin-10 (IL-10) in culture supernatants of BAC-treated HTFs was increased by coculture with HCE cells (17.26-fold, vs. coculure, p < 0.001). Immunofluorescence and immunoblot analyses also showed that exogenous IL-10 (300 pg/ml) suppressed the BAC-induced expression of αSMA by 43.65% (p < 0.05) as well as the nuclear translocation of myocardin-related transcription factor-A (MRTF-A) by 39.32% (p < 0.01) in HTFs cultured alone. Our findings suggest that corneal epithelial cells may protect against subconjunctival fibrosis by maintaining IL-10 levels and preventing the MRTF-A-dependent transdifferentiation of HTFs into myofibroblasts.

The EBV-Encoded Oncoprotein, LMP1, Recruits and Transforms Fibroblasts via an ERK-MAPK-Dependent Mechanism

Latent membrane protein 1 (LMP1), the major oncoprotein encoded by Epstein–Barr virus (EBV), is expressed at widely variable levels in undifferentiated nasopharyngeal carcinoma (NPC) biopsies, fueling intense debate in the field as to the importance of this oncogenic protein in disease pathogenesis. LMP1-positive NPCs are reportedly more aggressive, and in a similar vein, the presence of cancer-associated fibroblasts (CAFs) surrounding “nests” of tumour cells in NPC serve as indicators of poor prognosis. However, there is currently no evidence linking LMP1 expression and the presence of CAFs in NPC. In this study, we demonstrate the ability of LMP1 to recruit fibroblasts in vitro in an ERK-MAPK-dependent mechanism, along with enhanced viability, invasiveness and transformation to a myofibroblast-like phenotype. Taken together, these findings support a putative role for LMP1 in recruiting CAFs to the tumour microenvironment in NPC, ultimately contributing to metastatic disease.

Fenofibrate inhibits TGF-β-induced myofibroblast differentiation and activation in human lung fibroblasts in vitro

Fenofibrate (FF), a peroxisome proliferator-activated receptor-alpha (PPAR-α) agonist and a lipid-lowering agent, can decrease experimental pulmonary fibrosis. However, the mechanisms underlying the antifibrotic effect of FF remain unknown. Hence, this study was conducted to evaluate the effects of FF on transforming growth factor-beta (TGF-β)-induced myofibroblast differentiation and activation in lung fibroblasts. The results showed that FF inhibited alpha-smooth muscle actin (α-SMA) and connective tissue growth factor expression, collagen production, cell motility, SMAD3 phosphorylation and nuclear translocation, and metabolic reprogramming in TGF-β-exposed cells. The inhibitory effect of FF did not decrease with the addition of a PPAR-α antagonist. Moreover, the inhibitory effect given by FF could not be reproduced with the addition of an alternative PPAR-α agonist. FF inhibited mitochondrial respiration. However, rotenone, a complex I inhibitor, did not suppress TGF-β-induced myofibroblast differentiation. Furthermore, the TGF-β-induced nuclear reduction of protein phosphatase, Mg2+ /Mn2+ -dependent 1A (PPM1A), a SMAD phosphatase, was inhibited by FF. These results showed that FF suppressed TGF-β-induced myofibroblast differentiation and activation independent of PPAR-α activation and impaired mitochondrial respiration. In conclusion, this study provides information on the effects of FF on anti-TGF-β mechanisms.

Digital Imaging Analysis Reveals Reduced Alveolar α-Smooth Muscle Actin Expression in Severe Asthma

Expansion of α-smooth muscle actin (α-SMA)-expressing airway smooth muscle of the large airways in asthma is well-studied. However, the contribution of α-SMA-expressing cells in the more distal alveolated parenchyma, including pericytes and myofibroblasts within the alveolar septum, to asthma pathophysiology remains relatively unexplored. The objective of this study was to evaluate α-SMA expression in the alveolated parenchyma of individuals with severe asthma (SA), compared with healthy controls or individuals with chronic obstructive pulmonary disease. Using quantitative digital image analysis and video-assisted thoracoscopic surgery lung biopsies, we show that alveolated parenchyma α-SMA expression is markedly reduced in SA in comparison to healthy controls (mean %positive pixels: 12% vs. 23%, P=0.005). Chronic obstructive pulmonary disease cases showed a similar, but trending, decrease in α-SMA positivity compared with controls (mean %positivity: 17% vs. 23%, P=0.107), which may suggest loss of α-SMA expression is a commonality of obstructive lung diseases. The SA group had similar staining for ETS-related gene protein, a specific endothelial marker, comparatively to controls (mean %positive nuclei: 34% vs. 42%, P=0.218), which suggests intact capillary endothelium and likely intact capillary-associated, α-SMA-positive pericytes. These findings suggest that the loss of α-SMA expression in SA may be because of changes in myofibroblast α-SMA expression or cell number. Further study is necessary to fully evaluate possible mechanisms and consequences of this phenomenon.

Pterostilbene alleviates pulmonary fibrosis by regulating ASIC2

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a serious chronic disease of the respiratory system, but its current treatment has certain shortcomings and adverse effects. In this study, we evaluate the antifibrotic activity of pterostilbene (PTE) using an in vitro IPF model induced by transforming growth factor (TGF)-β1.

METHODS

A549 and alveolar epithelial cells (AECs) were incubated with 10 ng/ml TGF-β1 to induce lung fibroblast activation. Then, 30 μmol/L of PTE was used to treat these cells. The epithelial-mesenchymal transition (EMT), extracellular matrix (ECM) accumulation, and autophagy in cells were evaluated by western blot. Apoptosis was validated by flow cytometry analysis and western blot. Transcriptome high-throughput sequencing was performed on A549 cells incubated with TGF-β1 alone or TGF-β1 and PTE (TGF-β1 + PTE), and differentially expressed genes in PTE-treated cells were identified. The acid sensing ion channel subunit 2 (ASIC2) overexpression plasmid was used to rescue the protein levels of ASIC2 in A549 and AECs.

RESULTS

TGF-β1 caused EMT and ECM accumulation, and blocked the autophagy and apoptosis of A549 and AECs. Most importantly, 30 μmol/L of PTE inhibited pulmonary fibrosis induced by TGF-β1. Compared with TGF-β1, PTE inhibited EMT and ECM accumulation and rescued cell apoptosis and autophagy. The results of transcriptome high-throughput sequencing revealed that PTE greatly reduced the protein level of ASIC2. Compared with the TGF-β1 + PTE group, the transfection of ASIC2 overexpression plasmid stimulated the EMT and ECM accumulation and inhibited apoptosis and autophagy, suggesting that PTE inhibited pulmonary fibrosis by downregulating ASIC2.

CONCLUSIONS

This study suggests that PTE and ASIC2 inhibitors may have potential as IPF treatments in the future.

Epigenetic Reprogramming of Tumor-Associated Fibroblasts in Lung Cancer: Therapeutic Opportunities

Simple Summary

Lung cancer is the leading cause of cancer death among both men and women, partly due to limited therapy responses. New avenues of knowledge are indicating that lung cancer cells do not form a tumor in isolation but rather obtain essential support from their surrounding host tissue rich in altered fibroblasts. Notably, there is growing evidence that tumor progression and even the current limited responses to therapies could be prevented by rescuing the normal behavior of fibroblasts, which are critical housekeepers of normal tissue function. For this purpose, it is key to improve our understanding of the molecular mechanisms driving the pathologic alterations of fibroblasts in cancer. This work provides a comprehensive review of the main molecular mechanisms involved in fibroblast transformation based on epigenetic reprogramming, and summarizes emerging therapeutic approaches to prevent or overcome the pathologic effects of tumor-associated fibroblasts.

Abstract

Lung cancer is the leading cause of cancer-related death worldwide. The desmoplastic stroma of lung cancer and other solid tumors is rich in tumor-associated fibroblasts (TAFs) exhibiting an activated/myofibroblast-like phenotype. There is growing awareness that TAFs support key steps of tumor progression and are epigenetically reprogrammed compared to healthy fibroblasts. Although the mechanisms underlying such epigenetic reprogramming are incompletely understood, there is increasing evidence that they involve interactions with either cancer cells, pro-fibrotic cytokines such as TGF-β, the stiffening of the surrounding extracellular matrix, smoking cigarette particles and other environmental cues. These aberrant interactions elicit a global DNA hypomethylation and a selective transcriptional repression through hypermethylation of the TGF-β transcription factor SMAD3 in lung TAFs. Likewise, similar DNA methylation changes have been reported in TAFs from other cancer types, as well as histone core modifications and altered microRNA expression. In this review we summarize the evidence of the epigenetic reprogramming of TAFs, how this reprogramming contributes to the acquisition and maintenance of a tumor-promoting phenotype, and how it provides novel venues for therapeutic intervention, with a special focus on lung TAFs.

Role of Matrix Gla Protein in the Complex Network of Coronary Artery Disease: A Comprehensive Review

Coronary artery disease (CAD) is widely recognized as one of the most important clinical entities. In recent years, a large body of accumulated data suggest that coronary artery calcification, a process highly prevalent in patients with CAD, occurs via well-organized biologic processes, rather than passively, as previously regarded. Matrix Gla protein (MGP), a vitamin K-dependent protein, emerged as an important inhibitor of both intimal and medial vascular calcification. The functionality of MGP hinges on two post-translational modifications: phosphorylation and carboxylation. Depending on the above-noted modifications, various species of MGP may exist in circulation, each with their respective level of functionality. Emerging data suggest that dysfunctional species of MGP, markedly, dephosphorylated-uncarboxylated MGP, might find its application as biomarkers of microvascular health, and assist in clinical decision making with regard to initiation of vitamin K supplementation. Hence, in this review we summarized the current knowledge with respect to the role of MGP in the complex network of vascular calcification with concurrent inferences to CAD. In addition, we discussed the effects of warfarin use on MGP functionality, with concomitant implications to coronary plaque stability.

Mammals fail to regenerate organs when wound contraction drives scar formation

To understand why mammals generally do not regenerate injured organs, we considered the exceptional case of spontaneous skin regeneration in the early lamb fetus. Whereas during the early fetal stage skin wounds heal by regeneration, in the late fetal stage, and after birth, skin wounds close instead by scar formation. We review independent evidence that this switch in wound healing response coincides with the onset of wound contraction, which is also enabled during late fetal gestation. The crucial role of wound contraction in determining the wound healing outcome in adults has been demonstrated in three mammalian models of severe injury (excised guinea pig skin, transected rat sciatic nerve, excised rabbit conjunctival stroma) where grafting the injury with DRT, a contraction-blocking scaffold of highly-specific structure, altered significantly the wound healing outcome. While spontaneous healing resulted in scar formation in these animal models, DRT grafting significantly reduced the extent of wound contraction, prevented scar synthesis, and resulted in partial regeneration. These findings, as well as independent data from species that heal spontaneously via regeneration, point to a striking hypothesis: The process of regeneration lies dormant in mammals until appropriately activated by injury. In spontaneous wound healing of the late fetus and in adult mammals, wound contraction impedes such endogenous regeneration mechanisms. However, engineered treatments, such as DRT, that block wound contraction can cancel its effects and favor wound healing by regeneration instead of scar formation.

Fibroblasts: Origins, definitions, and functions in health and disease

Fibroblasts are diverse mesenchymal cells that participate in tissue homeostasis and disease by producing complex extracellular matrix and creating signaling niches through biophysical and biochemical cues. Transcriptionally and functionally heterogeneous across and within organs, fibroblasts encode regional positional information and maintain distinct cellular progeny. We summarize their development, lineages, functions, and contributions to fibrosis in four fibroblast-rich organs: skin, lung, skeletal muscle, and heart. We propose that fibroblasts are uniquely poised for tissue repair by easily reentering the cell cycle and exhibiting a reversible plasticity in phenotype and cell fate. These properties, when activated aberrantly, drive fibrotic disorders in humans.

Tempol differently affects cellular redox changes and antioxidant enzymes in various lung-related cells

Tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl) is a potential redox agent in cells. The present study investigated changes in cellular reactive oxygen species (ROS) and glutathione (GSH) levels and in antioxidant enzymes, in Tempol-treated Calu-6 and A549 lung cancer cells, normal lung WI-38 VA-13 cells, and primary pulmonary fibroblasts. Results demonstrated that Tempol (0.5–4 mM) either increased or decreased general ROS levels in lung cancer and normal cells at 48 h and specifically increased O₂^•− levels in these cells. In addition, Tempol differentially altered the expression and activity of antioxidant enzymes such as superoxide dismutase, catalase, and thioredoxin reductase1 (TrxR1) in A549, Calu-6, and WI-38 VA-13 cells. In particular, Tempol treatment increased TrxR1 protein levels in these cells. Tempol at 1 mM inhibited the growth of lung cancer and normal cells by about 50% at 48 h but also significantly induced cell death, as evidenced by annexin V-positive cells. Furthermore, down-regulation of TrxR1 by siRNA had some effect on ROS levels as well as cell growth inhibition and death in Tempol-treated or -untreated lung cells. In addition, some doses of Tempol significantly increased the numbers of GSH-depleted cells in both cancer cells and normal cells at 48 h. In conclusion, Tempol differentially increased or decreased levels of ROS and various antioxidant enzymes in lung cancer and normal cells, and induced growth inhibition and death in all lung cells along with an increase in O₂^•− levels and GSH depletion.

Mechanical and Thermodynamic Properties of Non-Muscle Contractile Tissues: The Myofibroblast and the Molecular Motor Non-Muscle Myosin Type IIA

Myofibroblasts are contractile cells found in multiple tissues. They are physiological cells as in the human placenta and can be obtained from bone marrow mesenchymal stem cells after differentiation by transforming growth factor-β (TGF-β). They are also found in the stroma of cancerous tissues and can be located in non-muscle contractile tissues. When stimulated by an electric current or after exposure to KCl, these tissues contract. They relax either by lowering the intracellular Ca2+ concentration (by means of isosorbide dinitrate or sildenafil) or by inhibiting actin-myosin interactions (by means of 2,3-butanedione monoxime or blebbistatin). Their shortening velocity and their developed tension are dramatically low compared to those of muscles. Like sarcomeric and smooth muscles, they obey Frank-Starling's law and exhibit the Hill hyperbolic tension-velocity relationship. The molecular motor of the myofibroblast is the non-muscle myosin type IIA (NMIIA). Its essential characteristic is the extreme slowness of its molecular kinetics. In contrast, NMIIA develops a unitary force similar to that of muscle myosins. From a thermodynamic point of view, non-muscle contractile tissues containing NMIIA operate extremely close to equilibrium in a linear stationary mode.

Tumor-Associated Fibroblast-Targeting Nanoparticles for Enhancing Solid Tumor Therapy: Progress and Challenges

Even though nanoparticle drug delivery systems (nanoDDSs) have improved antitumor efficacy by delivering more drugs to tumor sites compared to free and unencapsulated therapeutics, achieving satisfactory distribution and penetration of nanoDDSs inside solid tumors, especially in stromal fibrous tumors, remains challenging. As one of the most common stromal cells in solid tumors, tumor-associated fibroblasts (TAFs) not only promote tumor growth and metastasis but also reduce the drug delivery efficiency of nanoparticles through the tumor's inherent physical and physiological barriers. Thus, TAFs have been emerging as attractive targets, and TAF-targeting nanotherapeutics have been extensively explored to enhance the tumor delivery efficiency and efficacy of various anticancer agents. The purpose of this Review is to opportunely summarize the underlying mechanisms of TAFs on obstructing nanoparticle-mediated drug delivery into tumors and discuss the current advances of a plethora of nanotherapeutic approaches for effectively targeting TAFs.

Histatin 1 enhanced the speed and quality of wound healing through regulating the behaviour of fibroblast

Objectives

Histatin 1(Hst 1) has been proved to promote wound healing. However, there was no specific study on the regulation made by Hst 1 of fibroblasts in the process of wound healing. This research comprehensively studied the regulation of Hst 1 on the function of fibroblasts in the process of wound healing and preliminary mechanism about it.

Materials and methods

The full‐thickness skin wound model was made on the back of C57/BL6 mice. The wound healing, collagen deposition and fibroblast distribution were detected on days 3, 5 and 7 after injury. Fibroblast was cultured in vitro and stimulated with Hst 1, and then, their biological characteristics and functions were detected.

Results

Histatin 1 can effectively promote wound healing, improve collagen deposition during and after healing and increase the number and function of fibroblasts. After healing, the mechanical properties of the skin also improved. In vitro, the migration ability of fibroblasts stimulated by Hst 1 was significantly improved, and the fibroblasts transformed more into myofibroblasts, which improved the function of contraction and collagen secretion. In fibroblasts, mTOR signalling pathway can be activated by Hst 1.

Conclusions

Histatin 1 can accelerate wound healing and improve the mechanical properties of healed skin by promoting the function of fibroblasts. The intermolecular mechanisms need to be further studied, and this study provides a direction about mTOR signalling pathway.

Consequences of Extracellular Matrix Remodeling in Headway and Metastasis of Cancer along with Novel Immunotherapies: A Great Promise for Future Endeavor

Tissues are progressively molded by bidirectional correspondence between denizen cells and extracellular matrix (ECM) via cell-matrix connections along with ECM remodeling. The composition and association of ECM are spatiotemporally directed to control cell conduct and differentiation; however, dysregulation of ECM dynamics prompts the development of diseases, for example, cancer. Emerging information demonstrates that hypoxia may have decisive roles in metastasis. In addition, the sprawling nature of neoplastic cells and chaotic angiogenesis are increasingly influencing microcirculation as well as altering the concentration of oxygen. In various regions of the tumor microenvironment, hypoxia, an essential player in the multistep phase of cancer metastasis, is necessary. Hypoxia can be turned into an advantage for selective cancer therapy because it is much more severe in tumors than in normal tissues. Cellular matrix gives signaling cues that control cell behavior and organize cells' elements in tissue development and homeostasis. The interplay between intrinsic factors of cancer cells themselves, including their genotype and signaling networks, and extrinsic factors of tumor stroma, for example, ECM and ECM remodeling, together decide the destiny and behavior of tumor cells. Tumor matrix encourages the development, endurance, and invasion of neoplastic and immune cell activities to drive metastasis and debilitate treatment. Incipient evidence recommends essential parts of tumor ECM segments and their remodeling in controlling each progression of the cancer-immunity cycle. Scientists have discovered that tumor matrix dynamics as well as matrix remodeling in perspective to anti-tumor immune reactions are especially important for matrix-based biomarkers recognition and followed by immunotherapy and targeting specific drugs.

Lineage tracing of Foxd1-expressing embryonic progenitors to assess the role of divergent embryonic lineages on adult dermal fibroblast function

Recent studies have highlighted the functional diversity of dermal fibroblast populations in health and disease, with part of this diversity linked to fibroblast lineage and embryonic origin. Fibroblasts derived from foxd1-expressing progenitors contribute to the myofibroblast populations present in lung and kidney fibrosis in mice but have not been investigated in the context of dermal wound repair. Using a Cre/Lox system to genetically track populations derived from foxd1-expressing progenitors, lineage-positive fibroblasts were identified as a subset of the dermal fibroblast population. During development, lineage-positive cells were most abundant within the dorsal embryonic tissues, contributing to the developing dermal fibroblast population, and remaining in this niche into adulthood. In adult mice, assessment of fibrosis-related gene expression in lineage-positive and lineage-negative populations isolated from wounded and unwounded dorsal skin was performed, identifying an enrichment of transcripts associated with matrix synthesis and remodeling in the lineage-positive populations. Using a novel excisional wound model, ventral skin healed with a greatly reduced frequency of foxd1 lineage-positive cells. This work supports that the embryonic origin of fibroblasts is an important predictor of fibroblast function, but also highlights that within disparate regions, fibroblasts of different lineages likely undergo convergent differentiation contributing to phenotypic similarities.

Mechanism of bone marrow mesenchymal stem cells secreting miR-26a exosomes affecting high glucose-induced skin fibroblasts function by regulating TLR4/NF-κB signaling

OBJECTIVE

The aim of this study was to investigate the molecular mechanism of human bone marrow mesenchymal stem cells (hMSCs) secreting miR-26a exosomes on the function of skin fibroblasts.

METHODS

Exosomes from hMSCs were extracted and identified by transmission electron microscopy, particle size was analyzed and protein markers were detected. Then, the exosomes were co-cultured with human skin fibroblasts (BJ). CCK-8, Annexin V/P and Transwell assays were used to detect the proliferation, apoptosis, and migration of BJ cells. In addition, the expressions of miR-26a, related proteins, and related inflammatory factors were detected by qRT-PCR, western blotting, and ELISA.

RESULTS

Compared with the high glucose group, the proliferation rate, migration rate, and the expression of α-SMA, bcl-2, TLR4, NF-κB, TNF-α, IL-6, IL- and IL-1 were significantly decreased in the high glucose + MSC-Exo-miR-26a mimics group, while the apoptosis rate and the expression of miR-26a, cleaved-caspase 3, cleaved-caspase 9 and Bax were significantly increased. The results of the high glucose + MSC-Exo-miR-26a inhibitor group were the opposite.

CONCLUSION

These results suggest that hMSCs cells secreting miR-26a exosomes inhibited the proliferation, migration, and transdifferentiation of high glucose-induced BJ cells, and promoted cell apoptosis, which may be related to the TLR4/NF-κB signaling pathway.

Diabetic wound healing: The impact of diabetes on myofibroblast activity and its potential therapeutic treatments

Diabetes is a systemic disease in which the body cannot regulate the amount of sugar, namely glucose, in the blood. High glucose toxicity has been implicated in the dysfunction of diabetic wound healing, following insufficient production (Type 1) or inadequate usage (Type 2) of insulin. Chronic non-healing diabetic wounds are one of the major complications of both types of diabetes, which are serious concerns for public health and can impact the life quality of patients significantly. In general, diabetic wounds are characterized by deficient chemokine production, an unusual inflammatory response, lack of angiogenesis and epithelialization, and dysfunction of fibroblasts. Increasing scientific evidence from available experimental studies on animal and cell models strongly associates impaired wound healing in diabetes with dysregulated fibroblast differentiation to myofibroblasts, interrupted myofibroblast activity, and inadequate extracellular matrix production. Myofibroblasts play an important role in tissue repair by producing and organizing extracellular matrix and subsequently promoting wound contraction. Based on these studies, hyperglycaemic conditions can interfere with cytokine signalling pathways (such as growth factor-β pathway) affecting fibroblast differentiation, alter fibroblast apoptosis, dysregulate dermal lipolysis, and enhance hypoxia damage, thus leading to damaged microenvironment for myofibroblast formation, inappropriate extracellular matrix modulation, and weakened wound contraction. In this review, we will focus on the current available studies on the impact of diabetes on fibroblast differentiation and myofibroblast function, as well as potential treatments related to the affected pathways.

Circular RNA mmu_circ_0005019 inhibits fibrosis of cardiac fibroblasts and reverses electrical remodeling of cardiomyocytes

BACKGROUND

Circular RNA (circRNA) have been reported to play important roles in cardiovascular diseases including myocardial infarction and heart failure. However, the role of circRNA in atrial fibrillation (AF) has rarely been investigated. We recently found a circRNA hsa_circ_0099734 was significantly differentially expressed in the AF patients atrial tissues compared to paired control. We aim to investigate the functional role and molecular mechanisms of mmu_circ_0005019 which is the homologous circRNA in mice of hsa_circ_0099734 in AF.

METHODS

In order to investigate the effect of mmu_circ_0005019 on the proliferation, migration, differentiation into myofibroblasts and expression of collagen of cardiac fibroblasts, and the effect of mmu_circ_0005019 on the apoptosis and expression of Ito, INA and SK3 of cardiomyocytes, gain- and loss-of-function of cell models were established in mice cardiac fibroblasts and HL-1 atrial myocytes. Dual-luciferase reporter assays and RIP were performed to verify the binding effects between mmu_circ_0005019 and its target microRNA (miRNA).

RESULTS

In cardiac fibroblasts, mmu_circ_0005019 showed inhibitory effects on cell proliferation and migration. In cardiomyocytes, overexpression of mmu_circ_0005019 promoted Kcnd1, Scn5a and Kcnn3 expression. Knockdown of mmu_circ_0005019 inhibited the expression of Kcnd1, Kcnd3, Scn5a and Kcnn3. Mechanistically, mmu_circ_0005019 exerted biological functions by acting as a miR-499-5p sponge to regulate the expression of its target gene Kcnn3.

CONCLUSIONS

Our findings highlight mmu_circ_0005019 played a protective role in AF development and might serve as an attractive candidate target for AF treatment.

Advanced glycation end products activated endothelial-to-mesenchymal transition in pancreatic islet endothelial cells and triggered islet fibrosis in diabetic mice

Advanced glycation end products (AGEs) are associated with the pathogenesis of diabetic vascular complications. Induction of the endothelial-to-mesenchymal transition (EndMT) is associated with the pathogenesis of fibrotic diseases. The roles of AGEs in islet EndMT induction and diabetes-related islet microvasculopathy and fibrosis remain unclear. This study investigated the pathological roles of AGEs in islet EndMT induction and fibrosis in vitro and in vivo. Non-cytotoxic concentrations of AGEs upregulated the protein expression of fibronectin, vimentin, and α-smooth muscle actin (α-SMA) (mesenchymal/myofibroblast markers) and downregulated the protein expression of vascular endothelial (VE)-cadherin and cluster of differentiation (CD) 31 (endothelial cell markers) in cultured mouse pancreatic islet endothelial cells, which was prevented by the AGE cross-link breaker alagebrium chloride. In streptozotocin-induced diabetic mice, the average islet area and islet immunoreactivities for insulin and CD31 were decreased and the islet immunoreactivities for AGEs and α-SMA and fibrosis were increased, which were prevented by the AGE inhibitor aminoguanidine. Immunofluorescence double staining showed that α-SMA-positive staining co-localized with CD31-positive staining in the diabetic islets, which was effectively prevented by aminoguanidine. These results demonstrate that AGEs can induce EndMT in islet endothelial cells and islet fibrosis in diabetic mice, suggesting that AGE-induced EndMT may contribute to islet fibrosis in diabetes.

CircHIPK3 regulates pulmonary fibrosis by facilitating glycolysis in miR-30a-3p/FOXK2-dependent manner

Pulmonary fibrosis develops when myofibroblasts and extracellular matrix excessively accumulate in the injured lung, but what drives fibrosis is not fully understood. Glycolysis has been linked to cell growth and proliferation, and several studies have shown enhanced glycolysis promotes pulmonary fibrosis. However, detailed studies describing this switch remain limited. Here, we identified that TGF-β1 effectively increased the expression of circHIPK3 in lung fibroblasts, and circHIPK3 inhibition attenuated the activation, proliferation, and glycolysis of fibroblasts in vitro. Dual-luciferase reporter gene assays, RNA immunoprecipitation (RIP), and RNA pull-down assays showed that circHIPK3 could function as a sponge of miR-30a-3p and inhibit its expression. Furthermore, FOXK2, a driver transcription factor of glycolysis, was identified to be a direct target of miR-30a-3p. Mechanistically, circHIPK3 could enhance the expression of FOXK2 via sponging miR-30a-3p, thereby facilitating fibroblast glycolysis and activation. Besides, miR-30a-3p overexpression or FOXK2 knockdown blocked fibroblast activation induced by TGF-β1 and abrogated the profibrotic effects of circHIPK3. Moreover, circHIPK3 and miR-30a-3p were also dysregulated in fibrotic murine lung tissues induced by silica. Adeno-associated virus (AAV)-mediated circHIPK3 silence or miR-30a-3p overexpression alleviated silica-induced pulmonary fibrosis in vivo. In conclusion, our results identified circHIPK3/miR-30a-3p/FOXK2 regulatory pathway as an important glycolysis cascade in pulmonary fibrosis.

The Biological and Biomechanical Role of Transglutaminase-2 in the Tumour Microenvironment

Transglutaminase-2 (TG2) is the most highly and ubiquitously expressed member of the transglutaminase enzyme family and is primarily involved in protein cross-linking. TG2 has been implicated in the development and progression of numerous cancers, with a direct role in multiple cellular processes and pathways linked to apoptosis, chemoresistance, epithelial-mesenchymal transition, and stem cell phenotype. The tumour microenvironment (TME) is critical in the formation, progression, and eventual metastasis of cancer, and increasing evidence points to a role for TG2 in matrix remodelling, modulation of biomechanical properties, cell adhesion, motility, and invasion. There is growing interest in targeting the TME therapeutically in response to advances in the understanding of its critical role in disease progression, and a number of approaches targeting biophysical properties and biomechanical signalling are beginning to show clinical promise. In this review we aim to highlight the wide array of processes in which TG2 influences the TME, focussing on its potential role in the dynamic tissue remodelling and biomechanical events increasingly linked to invasive and aggressive behaviour. Drug development efforts have yielded a range of TG2 inhibitors, and ongoing clinical trials may inform strategies for targeting the biomolecular and biomechanical function of TG2 in the TME.

Cofilin-1 promotes fibrocyte differentiation and contributes to pulmonary fibrosis

Fibrocytes originate from the bone marrow monocyte lineage and participate in the pathogenesis of pulmonary fibrosis. Research providing a comprehensive picture of fibrocytes is still limited. Cofilin-1 (CFL-1) is an important protein that regulates cell proliferation, migration and differentiation. Whether CFL-1 can induce monocyte differentiation into fibrocytes and promote the process of pulmonary fibrosis is unknown. Compared with that of healthy controls, the expression of CFL-1 was significantly increased in the plasma and peripheral blood mononuclear cells (PBMCs) from idiopathic pulmonary fibrosis (IPF) and connective tissue disease-associated interstitial lung disease (CTD-ILD) patients (P < 0.05). The percentages of peripheral blood fibrocytes in the IPF group (4.2550 ± 0.3483%) and CTD-ILD group (4.7100 ± 0.4811%) were higher than that in the control group (1.6340 ± 0.2549%) (both P < 0.05). In vitro, PBMCs transfected with siRNA-CFL-1 showed lower expression of CFL-1, and the percentage of fibrocytes was lower than that of the control (P < 0.05). PBMCs transfected with Lv-CFL-1 to increase the expression of CFL-1 showed a higher percentage of fibrocytes than the control (P < 0.05). In mice with bleomycin-induced pulmonary fibrosis, the relative expression of CFL-1 was increased, and the percentage of fibrocytes was higher than that in the saline group (P < 0.05). In bleomycin-induced mice, interference with Lv-CFL-1 decreased the expression of CFL-1, the percentage of fibrocytes was lower, and the lung tissue showed less fibrosis (P < 0.05). The overexpression of CFL-1 is associated with pulmonary fibrogenesis. CFL-1 could promote the differentiation of fibrocytes from monocyte peripheral blood mononuclear cells and promote pulmonary fibrosis.

Micro- and nanoscale biophysical cues for cardiovascular disease therapy

After cardiovascular injury, numerous pathological processes adversely impact the homeostatic function of cardiomyocyte, macrophage, fibroblast, endothelial cell, and vascular smooth muscle cell populations. Subsequent malfunctioning of these cells may further contribute to cardiovascular disease onset and progression. By modulating cellular responses after injury, it is possible to create local environments that promote wound healing and tissue repair mechanisms. The extracellular matrix continuously provides these mechanosensitive cell types with physical cues spanning the micro- and nanoscale to influence behaviors such as adhesion, morphology, and phenotype. It is therefore becoming increasingly compelling to harness these cell-substrate interactions to elicit more native cell behaviors that impede cardiovascular disease progression and enhance regenerative potential. This review discusses recent in vitro and preclinical work that have demonstrated the therapeutic implications of micro- and nanoscale biophysical cues on cell types adversely affected in cardiovascular diseases - cardiomyocytes, macrophages, fibroblasts, endothelial cells, and vascular smooth muscle cells.

Cobalt exposure increases the risk of fibrosis of people living near E‑waste recycling area

The toxicity of heavy metals is one of the major public health issues leading to hazardous effects on humans. Many studies focus on the adverse effects on people who were working in or living near E-waste recycling. However, little is known to the sustaining effects of E-waste exposure on human health after the recycling factories were shut down. In the present study, we collected the blood of people living near E‑waste recycling facilities after the recycling factories were closed for 2 years. Eight heavy metals were examined in all blood samples. The results revealed that the blood levels of lead (Pb), nickel (Ni), cobalt (Co), mercury (Hg) were significantly higher in the exposed group than in the reference group, and no difference was observed for copper (Cu), zinc (Zn), stannum (Sn), cadmium (Cd). Transforming growth factor-β (TGF-β) and alpha-smooth muscle actin (α-SMA) were analyzed as the important indicators of fibrosis, which were statistically significantly higher in the exposed group than in the reference group. 8-isoprostane (8-I) and malondialdehyde (MDA) as the biomarkers of oxidative stress (OS) were elevated in the exposed group. Furthermore, both Spearman correlation and multiple linear regression showed that Co was positively correlated with TGF-β, α-SMA and 8-I in the exposed group. Accordingly, we speculate that high concentrations of Co dissolved in the blood may increase the risk of tissue fibrosis through stimulating myofibroblast activation and OS involve in the process, which may provide some potential new hints for the intervention for tissue fibrosis in the future.

FGF10 and Lipofibroblasts in Lung Homeostasis and Disease: Insights Gained From the Adipocytes

Adipocytes not only function as energy depots but also secrete numerous adipokines that regulate multiple metabolic processes, including lipid homeostasis. Dysregulation of lipid homeostasis, which often leads to adipocyte hypertrophy and/or ectopic lipid deposition in non-adipocyte cells such as muscle and liver, is linked to the development of insulin resistance. Similarly, an altered secretion profile of adipokines or imbalance between calorie intake and energy expenditure is associated with obesity, among other related metabolic disorders. In lungs, lipid-laden adipocyte-like cells known as lipofibroblasts share numerous developmental and functional similarities with adipocytes, and similarly influence alveolar lipid homeostasis by facilitating pulmonary surfactant production. Unsurprisingly, disruption in alveolar lipid homeostasis may propagate several chronic inflammatory disorders of the lung. Given the numerous similarities between the two cell types, dissecting the molecular mechanisms underlying adipocyte development and function will offer valuable insights that may be applied to, at least, some aspects of lipofibroblast biology in normal and diseased lungs. FGF10, a major ligand for FGFR2b, is a multifunctional growth factor that is indispensable for several biological processes, including development of various organs and tissues such as the lung and WAT. Moreover, accumulating evidence strongly implicates FGF10 in several key aspects of adipogenesis as well as lipofibroblast formation and maintenance, and as a potential player in adipocyte metabolism. This review summarizes our current understanding of the role of FGF10 in adipocytes, while attempting to derive insights on the existing literature and extrapolate the knowledge to pulmonary lipofibroblasts.

Transforming Growth Factor-Beta1 and Human Gingival Fibroblast-to-Myofibroblast Differentiation: Molecular and Morphological Modifications

After oral mucosal injury, the healing response following specific steps that lead to wound closure and to tissue repair. Multiple cell populations are involved in this process; in particular, fibroblasts play a key role in the production of extracellular matrix (ECM). During wound healing the remodeling of ECM is a key stage to restore the tissue functionality through multifunctional fibroblast populations that are placed in the connective tissues of gingiva and periodontal ligament. Notably, a fibroblast sub-type (myofibroblast) is centrally involved in collagen synthesis and fibrillar remodeling. The present work evidenced the role of Transforming Growth Factor-beta1 (TGF-β1) to mediate human gingival fibroblasts (hGFs) differentiation into myofibroblasts derived from gingival fibroblasts (myo-hGFs). The morphological and functional features were analyzed through Confocal Laser Scanning Microscopy (CLSM), flow cytometry, and western blotting analyses. The specific markers, such as alpha-Smooth Muscle Actin (α-SMA), Vimentin, E-cadherin, β-catenin, and Smad 2/3, were modulated in myo-hGFs after the induction with TGF-β1, at different time points (24, 48, and 72 h). After 72 h of treatment TGF-β1 operates as an inducer of hGFs into myo-hGFs differentiation. We propose that TGF-β1 may promote in vitro the fibroblasts-to-myofibroblasts transition via the morphological and molecular modifications, as the induction of α-SMA, Vimentin, E-cadherin, β-catenin, and Smad 2/3.

Activin A as a Novel Chemokine Induces Migration of L929 Fibroblasts by ERK Signaling in Microfluidic Devices

Activin A, a member of the transforming growth factor-beta (TGF-β) superfamily, contributes to tissue healing and fibrosis. As the innate tissue cells, fibroblasts also play an important role in wound healing and fibrosis. Herein, this study was aimed to investigate how activin A exhibited regulatory effects on adhesion and migration of fibroblasts. We found that activin A induced the migration of fibroblast cell line L929 cells in transwell chamber and microfluidic device. Activin A also promoted L929 cells adhesion, but did not affect L929 cells viability or proliferation. In addition, activin A induced α-SMA expression and TGF-β1 release, which were factors closely related to tissue fibrosis, but had no effect on IL-6 production, a pro-inflammatory cytokine. Furthermore, activin A elevated calcium levels in L929 cells and increased p-ERK protein levels. Activin A-induced migration of L929 cells was attenuated by ERK inhibitor FR180204. To conclude, these data indicated that activin A as a novel chemokine induced the chemotactic migration of L929 cells via ERK signaling and possessed the pro-fibrosis role. These findings provide a new insight into understanding of activin A in tissue fibrosis.

Targeting the TGF-β signaling pathway for fibrosis therapy: a patent review (2015-2020)

INTRODUCTION

Fibrosis is a serious disease that occurs in many organs, such as kidney, liver and lung. The deterioration of these organs ultimately leads to death. Due to the complex mechanisms of fibrosis, research and development of antifibrotic drugs is difficult. One solution is to focus on core pathways, one of which is the TGF-β signaling pathway. In virtually every type of fibrosis, TGF-β signaling is recognized as a critical pathway.

AREA COVERED

This review discusses patents on active molecules related to the TGF-β signaling. Molecules targeting components related to the activation of TGF-β are introduced. Several strategies preventing signal propagation from active TGF-β to downstream targets are also introduced, including TGF-β antibodies, TGF-β ligand traps, and inhibitors of TGF-β receptor kinases. Finally, molecules affecting downstream targets in both canonical and noncanonical TGF-β signaling pathways are described.

EXPERT OPINION

Since the approval of pirfenidone, targeting TGF-β signaling has been anticipated as an effective therapy for fibrosis. The potential of this therapy has been further supported by emerging patents on the TGF-β signaling. This pathway can be entirely inhibited, from the activation of TGF-β to downstream signaling. Inhibiting TGF-β signaling is expected to provide more effective treatments for fibrosis.

Beneficial impact of cathelicidin on hypersensitivity pneumonitis treatment-In vivo studies

Cathelicidin (CRAMP) is a defence peptide with a wide range of biological responses including antimicrobial, immunomodulatory and wound healing. Due to its original properties the usefulness of CRAMP in the treatment of pulmonary fibrosis was assessed in a murine model of hypersensitivity pneumonitis (HP). The studies were conducted on mouse strain C57BL/6J exposed to a saline extract of Pantoea agglomerans cells (HP inducer). Cathelicidin was administered in the form of an aerosol during and after HP development. Changes in the composition of immune cell populations (NK cells, macrophages, lymphocytes: Tc, Th, Treg, B), were monitored in lung tissue by flow cytometry. Extracellular matrix deposition (collagens, hydroxyproline), the concentration of cytokines involved in inflammatory and the fibrosis process (IFNγ, TNFα, TGFβ1, IL1β, IL4, IL5, IL10, IL12α, IL13) were examined in lung homogenates by the ELISA method. Alterations in lung tissue morphology were examined in mouse lung sections stained with haematoxylin and eosin as well as Masson trichrome dyes. The performed studies revealed that cathelicidin did not cause any negative changes in lung morphology/structure, immune cell composition or cytokines production. At the same time, CRAMP attenuated the immune reaction induced by mice chronic exposure to P. agglomerans and inhibited hydroxyproline and collagen deposition in the lung tissue of mice treated with bacteria extract. The beneficial effect of CRAMP on HP treatment was associated with restoring the balance in quantity of immune cells, cytokines production and synthesis of extracellular matrix components. The presented study suggests the usefulness of cathelicidin in preventing lung fibrosis; however, cathelicidin was not able to reverse pathological changes completely.

Sterile Injury Repair and Adhesion Formation at Serosal Surfaces

Most multicellular organisms have a major body cavity containing vital organs. This cavity is lined by a mucosa-like serosal surface and filled with serous fluid which suspends many immune cells. Injuries affecting the major body cavity are potentially life-threatening. Here we summarize evidence that unique damage detection and repair mechanisms have evolved to ensure immediate and swift repair of injuries at serosal surfaces. Furthermore, thousands of patients undergo surgery within the abdominal and thoracic cavities each day. While these surgeries are potentially lifesaving, some patients will suffer complications due to inappropriate scar formation when wound healing at serosal surfaces defects. These scars called adhesions cause profound challenges for health care systems and patients. Therefore, reviewing the mechanisms of wound repair at serosal surfaces is of clinical importance. Serosal surfaces will be introduced with a short embryological and microanatomical perspective followed by a discussion of the mechanisms of damage recognition and initiation of sterile inflammation at serosal surfaces. Distinct immune cells populations are free floating within the coelomic (peritoneal) cavity and contribute towards damage recognition and initiation of wound repair. We will highlight the emerging role of resident cavity GATA6+ macrophages in repairing serosal injuries and compare serosal (mesothelial) injuries with injuries to the blood vessel walls. This allows to draw some parallels such as the critical role of the mesothelium in regulating fibrin deposition and how peritoneal macrophages can aggregate in a platelet-like fashion in response to sterile injury. Then, we discuss how serosal wound healing can go wrong, causing adhesions. The current pathogenetic understanding of and potential future therapeutic avenues against adhesions are discussed.

Integrin αVβ1 regulates procollagen I production through a non-canonical transforming growth factor β signaling pathway in human hepatic stellate cells

Hepatic stellate cells (HSCs) are thought to play key roles in the development of liver fibrosis. Extensive evidence has established the concept that αV integrins are involved in the activation of latent transforming growth factor β (TGF-β), a master regulator of the fibrotic signaling cascade. Based on mRNA and protein expression profiling data, we found that αVβ1 integrin is the most abundant member of the αV integrin family in either quiescent or TGF-β1-activated primary human HSCs. Unexpectedly, either a selective αVβ1 inhibitor, Compound 8 (C8), or a pan-αV integrin inhibitor, GSK3008348, decreased TGF-β1-activated procollagen I production in primary human HSCs, in which the role of β1 integrin was confirmed by ITGB1 siRNA. In contrast with an Activin receptor-like kinase 5 (Alk5) inhibitor, C8 and GSK3008348 failed to inhibit TGF-β1 induced SMAD3 and SMAD2 phosphorylation, but inhibited TGF-β-induced phosphorylation of ERK1/2 and STAT3, suggesting that αVβ1 integrin is involved in non-canonical TGF-β signaling pathways. Consistently, ITGB1 siRNA significantly decreased phosphorylation of ERK1/2. Furthermore, a selective inhibitor of MEK1/2 blocked TGF-β1 induced phosphorylation of ERK1/2 and decreased TGF-β1 induced procollagen I production, while a specific inhibitor of STAT3 had no effect on TGF-β1 induced procollagen I production. Taken together, current data indicate that αVβ1 integrin can regulate TGF-β signaling independent of its reported role in activating latent TGF-β. Our data further support that αVβ1 inhibition is a promising therapeutic target for the treatment of liver fibrosis.

Honokiol inhibits arecoline-induced oral fibrogenesis through transforming growth factor-β/Smad2/3 signaling inhibition

BACKGROUND/PURPOSE

The habit of areca nut chewing has been regarded as an etiological factor of precancerous oral submucous fibrosis (OSF). In the present study, we aimed to evaluate the anti-fibrosis effect of honokiol, a polyphenolic component derived from Magnolia officinalis.

METHODS

The cytotoxicity of honokiol was tested using normal and fibrotic buccal mucosal fibroblasts (fBMFs) derived from OSF tissues. Collagen gel contraction, Transwell migration, invasion, and wound healing capacities were examined. Besides, the expression of TGF-β/Smad2 signaling as well as α-SMA and type I collagen were measured as well.

RESULTS

Honokiol exerted higher cytotoxicity of fBMFs compared to normal cells. The arecoline-induced myofibroblast activities, including collagen gel contractility, cell motility and wound healing capacities were all suppressed by honokiol treatment. In addition, the expression of the TGF-β/Smad2 pathway was downregulated along with a lower expression of α-SMA and type I collagen in honokiol-receiving cells.

CONCLUSION

Our data suggest that honokiol may be a promising compound to alleviate the progression of oral fibrogenesis and prevent the transformation of OSF oral epithelium into cancer.