Fibroblast growth factor-1 attenuates TGF-β1-induced lung fibrosis

Single-cell transcriptomics reveals the mechanisms of lung injury induced by galt gene editing in mouse

Galactosemia, caused by mutations in the GALT gene, leads to multi-organ damage. This study investigates the impact of Galt c.847 + 1G > T mutation on lung tissue using single-cell transcriptomics. We employed CRISPR/Cas9 to generate a Galt gene-edited mouse model with the Galt c. 847 + 1G > T mutation and assessed Galt expression through PCR and Western blotting. Histopathological analysis revealed significant structural lung changes, including alveolar congestion and inflammation. Single-cell RNA sequencing demonstrated a marked reduction in immune cells (NK, T, macrophages, B cells) and an increase in alveolar type II cells, vascular endothelial cells, and myofibroblasts in the GAL mouse. The increased abundance of alveolar type II cells indicated impaired differentiation and repair. Metabolic analysis revealed significant abnormalities linked to Galt c.847 + 1G > T mutation, with disruptions in TGF-β1, FGF, and Mif pathways contributing to cellular dysfunction and exacerbated lung injury. This model provides insights into the molecular mechanisms of lung injury in galactosemia, highlighting significant alterations in lung cell populations and key signaling pathways.

A review of recent studies on the pathogenesis of Systemic Sclerosis: focus on fibrosis pathways

Systemic Sclerosis (SSc) is a systemic autoimmune disease of unknown etiology characterized by the development of frequently progressive cutaneous and internal organ fibrosis accompanied by severe vascular alterations. The pathogenesis of SSc is highly complex and, despite extensive investigation, has not been fully elucidated. Numerous studies have suggested that unknown etiologic factors cause multiple alterations in genetically receptive hosts, leading to SSc development and progression. These events may be functionally and pathologically interconnected and include: 1) Structural and functional microvascular and endothelial cell abnormalities; 2) Severe oxidative stress and high reactive oxygen species (3); Frequently progressive cutaneous and visceral fibrosis; 4) Transdifferentiation of various cell types into activated myofibroblasts, the cells ultimately responsible for the fibrotic process; 5) Establishment of a chronic inflammatory process in various affected tissues; 6) Release of cytokines, chemokines, and growth factors from the inflammatory cells; 7) Abnormalities in humoral and cellular immunity with the production of specific autoantibodies; and 8) Epigenetic alterations including changes in multiple non-coding RNAs. These events manifest with different levels of intensity in the affected organs and display remarkable individual variability, resulting in a wide heterogeneity in the extent and severity of clinical manifestations. Here, we will review some of the recent studies related to SSc pathogenesis.

FGF and TGF-β growth factor isoform modulation of human gingival and periodontal ligament fibroblast wound healing phenotype

Release of growth factors in the tissue microenvironment is a critical process in the repair and regeneration of periodontal tissues, regulating fibroblast behavior and phenotype. As a result of the complex architecture of the periodontium, distinct fibroblast populations in the periodontal ligament and gingival connective tissue exist in close proximity. Growth factor therapies for periodontal regeneration have gained traction, but quantification of their effects on multiple different fibroblast populations that are required for repair has been poorly investigated. In this study, we examined the effects of TGF-β1, TGF-β3, FGF-2, and FGF-9 on human gingival fibroblasts (hGF) and human periodontal ligament cells (hPDL), as well as the combined effects of TGF-β3 and FGF-2. We show that FGF-2 enhances cell migration while TGF-β1 and TGF-β3 promotes matrix production, and TGF-β1 promotes fibroblast to myofibroblast transition. Interestingly, the combination of TGF-β3 and FGF-2, acting through both p-SMAD3 and p-ERK pathways, mitigates the inhibitory effects of TGF-β3 on migration in hPDL cells, suggesting synergistic and complimentary effects of FGF-2 and TGF-β3. Additionally, fibronectin production in hGF increased when treated with the combined TGF-β3+FGF-2 compared to FGF-2 alone, indicating that the effects of TGF-β3 in promoting extracellular matrix production are still active in the combined treatment condition. Finally, our study highlights that FGF-9 did not influence migration, α-SMA expression, or extracellular matrix production in either cell type, emphasizing the unique roles of specific growth factors in cellular responses. The synergistic effects observed with combined TGF-β3 and FGF-2 treatments present promising avenues for further research and clinical advancements in regenerative medicine.

PI3K/Akt in IPF: untangling fibrosis and charting therapies

Idiopathic Pulmonary Fibrosis (IPF) is a chronic, progressive lung disease characterized by abnormal epithelial repair, persistent inflammation, and excessive extracellular matrix deposition, leading to irreversible scarring and respiratory failure. Central to its pathogenesis is the dysregulation of the PI3K/Akt signaling pathway, which drives fibroblast activation, epithelial-mesenchymal transition, apoptosis resistance, and cellular senescence. Senescent cells contribute to fibrosis through the secretion of pro-inflammatory and profibrotic factors in the senescence-associated secretory phenotype (SASP). Current antifibrotic therapies, Nintedanib and Pirfenidone, only slow disease progression and are limited by side effects, highlighting the need for novel treatments. This review focuses on the role of PI3K/Akt signaling in IPF pathogenesis, its intersection with inflammation and fibrosis, and emerging therapeutic approaches targeting molecules along this pathway.

An FGF2-Derived Short Peptide Attenuates Bleomycin-Induced Pulmonary Fibrosis by Inhibiting Collagen Deposition and Epithelial-Mesenchymal Transition via the FGFR/MAPK Signaling Pathway

Following the COVID-19 pandemic, the prevalence of pulmonary fibrosis has increased significantly, placing patients at higher risk and presenting new therapeutic challenges. Current anti-fibrotic drugs, such as Nintedanib, can slow the decline in lung function, but their severe side effects highlight the urgent need for safer and more targeted alternatives. This study explores the anti-fibrotic potential and underlying mechanisms of an endogenous peptide (P5) derived from fibroblast growth factor 2 (FGF2), developed by our research team. Using a bleomycin-induced pulmonary fibrosis mouse model, we observed that P5 alleviated fibrosis by inhibiting collagen deposition, as confirmed by CT scans and histological staining. In TGF-β-induced cell models, P5 effectively suppressed collagen deposition and epithelial-mesenchymal transition (EMT). Transcriptome analysis highlighted pathways related to receptor binding, extracellular matrix organization, and cell adhesion, with KEGG analysis confirming FGFR/MAPK signaling inhibition as the primary mechanism underlying its anti-fibrotic effects. In summary, our study demonstrates that P5 significantly attenuates pulmonary fibrosis through the inhibition of EMT, collagen deposition, and FGFR/MAPK signaling, providing a promising therapeutic approach for fibrosis.

Cellular Transdifferentiation: A Crucial Mechanism of Fibrosis in Systemic Sclerosis

Systemic Sclerosis (SSc) is a systemic autoimmune disease of unknown etiology with a highly complex pathogenesis that despite extensive investigation is not completely understood. The clinical and pathologic manifestations of the disease result from three distinct processes: 1) Severe and frequently progressive tissue fibrosis causing exaggerated and deleterious accumulation of interstitial collagens and other extracellular matrix molecules in the skin and various internal organs; 2) extensive fibroproliferative vascular lesions affecting small arteries and arterioles causing tissue ischemic alterations; and 3) cellular and humoral immunity abnormalities with the production of numerous autoantibodies, some with very high specificity for SSc. The fibrotic process in SSc is one of the main causes of disability and high mortality of the disease. Owing to its essentially universal presence and the severity of its clinical effects, the mechanisms involved in the development and progression of tissue fibrosis have been extensively investigated, however, despite intensive investigation, the precise molecular mechanisms have not been fully elucidated. Several recent studies have suggested that cellular transdifferentiation resulting in the phenotypic conversion of various cell types into activated myofibroblasts may be one important mechanism. Here, we review the potential role that cellular transdifferentiation may play in the development of severe and often progressive tissue fibrosis in SSc.

Derazantinib Inhibits the Bioactivity of Keloid Fibroblasts via FGFR Signaling

Keloids are common benign cutaneous pathological fibrous proliferation diseases, which are difficult to cure and easily recur. Studies have shown that fibroblast growth factor receptor-1 (FGFR1) was enhanced in pathological fibrous proliferation diseases, such as cirrhosis and idiopathic pulmonary fibrosis (IPF), suggesting the FGFR1 pathway has potential for keloid treatment. Derazantinib is a selective FGFR inhibitor with antiproliferative activity in in vitro and in vivo models. The present study determined the effects of derazantinib on human keloid fibroblasts (KFs). Cell viability assay, migration assay, invasion assay, immunofluorescence staining, quantitative polymerase chain reaction, Western blot analysis, HE staining, Masson staining, and immunohistochemical analysis were used to analyze the KFs and keloid xenografts. In this study, we found that derazantinib inhibited the proliferation, migration, invasion, and collagen production of KFs in vitro. The transcription and expression of plasminogen activator inhibitor-1 (PAI-1), which is closely related to collagen deposition and tissue fibrosis, was significantly inhibited. Also, derazantinib inhibited the expression of FGFR1 and PAI-1 and reduced the weight of the implanted keloid from the xenograft mice model. These findings suggest that derazantinib may be a potent therapy for keloids via FGFR signaling.

lncRNA TUG1 as potential novel biomarker for prognosis of cardiovascular diseases

Globally, cardiovascular diseases (CVDs) are among the leading causes of death. In light of the high prevalence and mortality of CVDs, it is imperative to understand the molecules involved in CVD pathogenesis and the signaling pathways that they initiate. This may facilitate the development of more precise and expedient diagnostic techniques, the identification of more effective prognostic molecules and the identification of potential therapeutic targets. Numerous studies have examined the role of lncRNAs, such as TUG1, in CVD pathogenesis in recent years. According to this review article, TUG1 can be considered a biomarker for predicting the prognosis of CVD.

Emerging opportunities to treat idiopathic pulmonary fibrosis: Design, discovery, and optimizations of small-molecule drugs targeting fibrogenic pathways

Idiopathic pulmonary fibrosis (IPF) is the most common fibrotic form of idiopathic diffuse lung disease. Due to limited treatment options, IPF patients suffer from poor survival. About ten years ago, Pirfenidone (Shionogi, 2008; InterMune, 2011) and Nintedanib (Boehringer Ingelheim, 2014) were approved, greatly changing the direction of IPF drug design. However, limited efficacy and side effects indicate that neither can reverse the process of IPF. With insights into the occurrence of IPF, novel targets and agents have been proposed, which have fundamentally changed the treatment of IPF. With the next-generation agents, targeting pro-fibrotic pathways in the epithelial-injury model offers a promising approach. Besides, several next-generation IPF drugs have entered phase II/III clinical trials with encouraging results. Due to the rising IPF treatment requirements, there is an urgent need to completely summarize the mechanisms, targets, problems, and drug design strategies over the past ten years. In this review, we summarize known mechanisms, target types, drug design, and novel technologies of IPF drug discovery, aiming to provide insights into the future development and clinical application of next-generation IPF drugs.

Pulmonary Fibrosis as a Result of Acute Lung Inflammation: Molecular Mechanisms, Relevant In Vivo Models, Prognostic and Therapeutic Approaches

Pulmonary fibrosis is a chronic progressive lung disease that steadily leads to lung architecture disruption and respiratory failure. The development of pulmonary fibrosis is mostly the result of previous acute lung inflammation, caused by a wide variety of etiological factors, not resolved over time and causing the deposition of fibrotic tissue in the lungs. Despite a long history of study and good coverage of the problem in the scientific literature, the effective therapeutic approaches for pulmonary fibrosis treatment are currently lacking. Thus, the study of the molecular mechanisms underlying the transition from acute lung inflammation to pulmonary fibrosis, and the search for new molecular markers and promising therapeutic targets to prevent pulmonary fibrosis development, remain highly relevant tasks. This review focuses on the etiology, pathogenesis, morphological characteristics and outcomes of acute lung inflammation as a precursor of pulmonary fibrosis; the pathomorphological changes in the lungs during fibrosis development; the known molecular mechanisms and key players of the signaling pathways mediating acute lung inflammation and pulmonary fibrosis, as well as the characteristics of the most common in vivo models of these processes. Moreover, the prognostic markers of acute lung injury severity and pulmonary fibrosis development as well as approved and potential therapeutic approaches suppressing the transition from acute lung inflammation to fibrosis are discussed.

Placental proteins with predicted roles in fetal development decrease in premature infants

BACKGROUND

Emerging evidence from animal experiments indicate that factors secreted by the placenta are critical for normal fetal organ development. Our objective was to characterize the umbilical vein and artery proteome in preterm infants and identify proteins that decrease in the neonatal circulation following delivery.

METHODS

Cord blood at delivery and neonatal blood at 48-72 h of life was collected in 25 preterm infants. Plasma protein abundance was determined using the SomaLogic platform.

RESULTS

When comparing protein levels of umbilical venous to arterial cord blood, 434 proteins were significantly higher indicating placental secretion into the fetal circulation. Moreover, when comparing neonatal blood to umbilical vein levels, 142 proteins were significantly lower. These proteins included Endoplasmic reticulum resident protein 29, CD59, Fibroblast growth factor 2 and Dynactin subunit 2, which are involved in brain development and prevention of brain damage as well as Fibroblast growth factor 1 which prevents lung fibrosis.

CONCLUSIONS

The late second trimester human placenta secretes proteins into the fetal circulation which decrease following delivery. Many of these proteins are predicted to be important in the development of fetal organs. Further studies are needed to directly link placental proteins to organ development and poor outcomes in preterm infants.

IMPACT

Prematurity remains a leading cause of morbidity and mortality requiring the development of novel treatments. Emerging evidence from animal studies suggest that factors secreted from the placenta may be critical in the development of the fetus. We report that the preterm human placenta secretes an array of proteins into the fetal circulation. Some of these proteins are predicted to be involved in the development of the brain and the lung. When born prematurely, infants are deprived of these placental proteins, which may contribute to their poor outcomes.

Aqueous Humor Growth Factor Levels and Trabeculectomy Outcomes in Primary Open-Angle Glaucoma Patients: A 2-Year Prospective Study

Purpose

Maintenance of a filtering bleb is essential for long-term intraocular pressure control after trabeculectomy. Surgical site fibrosis and excessive extracellular matrix production are common causes of trabeculectomy failure, mediated by several growth factors. We aimed to evaluate the levels of five growth factors and their correlation with trabeculectomy outcomes in patients with primary open-angle glaucoma (POAG).

Methods

We collected aqueous humor samples intraoperatively from patients with POAG who underwent trabeculectomy and measured the concentrations of transforming growth factor-β (TGF-β), acidic fibroblast growth factor (aFGF), insulin-like growth factor-1, vascular endothelial growth factor, and platelet-derived growth factor using multiplexed immunoassay kits. Intraocular pressure was measured with Goldmann applanation tonometry at 1 week and at 1, 3, 6, 12, 18, and 24 months after trabeculectomy. We allocated the eyes based on surgical outcome into a success or failure group.

Results

Significantly high levels of aFGF and TGF-β were observed in the failure group (both P < 0.0001) and were significant risk factors for trabeculectomy outcomes. Higher success rates were observed over the 24-month follow-up period in eyes with low aFGF and TGF-β levels compared to eyes with high levels (P = 0.0031 and P = 0.0007, respectively). The levels of TGF-β were significantly positively correlated with aFGF.

Conclusions

In POAG patients, high aFGF and TGF-β levels were significant risk factors for trabeculectomy failure.

Translational Relevance

Modulation of aFGF and TGF-β expression may have potential clinical applications after filtration surgery.

Functions of exogenous FGF signals in regulation of fibroblast to myofibroblast differentiation and extracellular matrix protein expression

Fibroblasts are widely distributed cells found in most tissues and upon tissue injury, they are able to differentiate into myofibroblasts, which express abundant extracellular matrix (ECM) proteins. Overexpression and unordered organization of ECM proteins cause tissue fibrosis in damaged tissue. Fibroblast growth factor (FGF) family proteins are well known to promote angiogenesis and tissue repair, but their activities in fibroblast differentiation and fibrosis have not been systematically reviewed. Here we summarize the effects of FGFs in fibroblast to myofibroblast differentiation and ECM protein expression and discuss the underlying potential regulatory mechanisms, to provide a basis for the clinical application of recombinant FGF protein drugs in treatment of tissue damage.

New developments in the biology of fibroblast growth factors

The fibroblast growth factor (FGF) family is composed of 18 secreted signaling proteins consisting of canonical FGFs and endocrine FGFs that activate four receptor tyrosine kinases (FGFRs 1-4) and four intracellular proteins (intracellular FGFs or iFGFs) that primarily function to regulate the activity of voltage-gated sodium channels and other molecules. The canonical FGFs, endocrine FGFs, and iFGFs have been reviewed extensively by us and others. In this review, we briefly summarize past reviews and then focus on new developments in the FGF field since our last review in 2015. Some of the highlights in the past 6 years include the use of optogenetic tools, viral vectors, and inducible transgenes to experimentally modulate FGF signaling, the clinical use of small molecule FGFR inhibitors, an expanded understanding of endocrine FGF signaling, functions for FGF signaling in stem cell pluripotency and differentiation, roles for FGF signaling in tissue homeostasis and regeneration, a continuing elaboration of mechanisms of FGF signaling in development, and an expanding appreciation of roles for FGF signaling in neuropsychiatric diseases. This article is categorized under: Cardiovascular Diseases > Molecular and Cellular Physiology Neurological Diseases > Molecular and Cellular Physiology Congenital Diseases > Stem Cells and Development Cancer > Stem Cells and Development.

Protective effect of ebselen on bleomycin-induced lung fibrosis: analysis of the molecular mechanism of lung fibrosis mediated by oxidized diacylglycerol

The molecular mechanisms underlying the development of pulmonary fibrosis remain unknown, and effective treatments have not yet been developed. It has been shown that oxidative stress is involved in lung fibrosis. Oxidized diacylglycerol (DAG) produced by oxidative stress is thought to play an important role in lung fibrosis. This study assessed the effect of oxidized DAG in an animal model of pulmonary fibrosis induced by aspiration of bleomycin (BLM) into the lungs. The inhibitory effect of ebselen on pulmonary fibrosis was also investigated. In lung fibrotic tissue induced by BLM, an increase in lipid peroxides and collagen accumulation was observed. Moreover, the levels of oxidized DAG, which has strong protein kinase C (PKC) activation activity, were significantly increased over time following the administration of BLM. Western blotting showed that phosphorylation of PKCα and δ isoforms was increased by BLM. Oral administration of ebselen significantly suppressed the increase in oxidized DAG induced by BLM and improved lung fibrosis. PKCα and δ phosphorylation were also significantly inhibited. The mRNA expression of α-smooth muscle actin and collagen I (marker molecules for fibrosis), as well as the production of transforming growth factor-β and tumor necrosis factor-α(a potentially important factor in the fibrotic process), were increased by BLM and significantly decreased by ebselen. The administration of BLM may induce lipid peroxidation in lung tissue, while the oxidized DAG produced by BLM may induce overactivation of PKCα and δ, resulting in the induction of lung fibrosis.

Targeting fibrosis, mechanisms and cilinical trials

Fibrosis is characterized by the excessive extracellular matrix deposition due to dysregulated wound and connective tissue repair response. Multiple organs can develop fibrosis, including the liver, kidney, heart, and lung. Fibrosis such as liver cirrhosis, idiopathic pulmonary fibrosis, and cystic fibrosis caused substantial disease burden. Persistent abnormal activation of myofibroblasts mediated by various signals, such as transforming growth factor, platelet-derived growth factor, and fibroblast growh factor, has been recongized as a major event in the occurrence and progression of fibrosis. Although the mechanisms driving organ-specific fibrosis have not been fully elucidated, drugs targeting these identified aberrant signals have achieved potent anti-fibrotic efficacy in clinical trials. In this review, we briefly introduce the aetiology and epidemiology of several fibrosis diseases, including liver fibrosis, kidney fibrosis, cardiac fibrosis, and pulmonary fibrosis. Then, we summarise the abnormal cells (epithelial cells, endothelial cells, immune cells, and fibroblasts) and their interactions in fibrosis. In addition, we also focus on the aberrant signaling pathways and therapeutic targets that regulate myofibroblast activation, extracellular matrix cross-linking, metabolism, and inflammation in fibrosis. Finally, we discuss the anti-fibrotic drugs based on their targets and clinical trials. This review provides reference for further research on fibrosis mechanism, drug development, and clinical trials.

Targeting Growth Factor and Cytokine Pathways to Treat Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic interstitial lung disease of unknown origin that usually results in death from secondary respiratory failure within 2–5 years of diagnosis. Recent studies have identified key roles of cytokine and growth factor pathways in the pathogenesis of IPF. Although there have been numerous clinical trials of drugs investigating their efficacy in the treatment of IPF, only Pirfenidone and Nintedanib have been approved by the FDA. However, they have some major limitations, such as insufficient efficacy, undesired side effects and poor pharmacokinetic properties. To give more insights into the discovery of potential targets for the treatment of IPF, this review provides an overview of cytokines, growth factors and their signaling pathways in IPF, which have important implications for fully exploiting the therapeutic potential of targeting cytokine and growth factor pathways. Advances in the field of cytokine and growth factor pathways will help slow disease progression, prolong life, and improve the quality of life for IPF patients in the future.

FGF19 is Downregulated in Idiopathic Pulmonary Fibrosis and Inhibits Lung Fibrosis in Mice

IPF is a devastating lung disease with limited therapeutic possibilities. FGF19, an endocrine FGF, was recently shown to decrease liver fibrosis. To ask whether FGF19 had anti-fibrotic properties in the lung and decipher its effects on common features associated with lung fibrogenesis. We assessed, by Elisa, FGF19 levels in plasma and bronchoalveolar lavage fluids (BALF)obtained from controls and IPF patients. In vivo, using an intravenously administered adeno11 associated virus (AAV), we overexpressed FGF19 at the fibrotic phase of two experimental models of murine lung fibrosis and assessed its effect on lung morphology, lung collagen content, fibrosis markers and pro fibrotic mediator expression, at mRNA and protein levels. In vitro, we investigated whether FGF19 could modulate the TGFβ-induced differentiation of primary human lung fibroblast into myofibroblast and the apoptosis of murine alveolar type II cell. While FGF19 was not detected in BALF, FGF19 concentration was decreased in the plasma of IPF patients compared to controls. In vivo, the overexpression of FGF19 was associated with a marked decrease of lung fibrosis and fibrosis markers, with a decrease of pro fibrotic mediator expression and lung collagen content. In vitro, FGF19 decreased alveolar type 2 epithelial cell apoptosis through the decrease of the proapoptotic BIM protein expression and prevented TGF-ß induced myofibroblast differentiation through the inhibition of JNK phosphorylation. Altogether these data identify FGF19 as an anti-fibrotic molecule with a potential therapeutic interest in fibrotic lung disorders.

Roles of the fibroblast growth factor signal transduction system in tissue injury repair

Following injury, tissue autonomously initiates a complex repair process, resulting in either partial recovery or regeneration of tissue architecture and function in most organisms. Both the repair and regeneration processes are highly coordinated by a hierarchy of interplay among signal transduction pathways initiated by different growth factors, cytokines and other signaling molecules under normal conditions. However, under chronic traumatic or pathological conditions, the reparative or regenerative process of most tissues in different organs can lose control to different extents, leading to random, incomplete or even flawed cell and tissue reconstitution and thus often partial restoration of the original structure and function, accompanied by the development of fibrosis, scarring or even pathogenesis that could cause organ failure and death of the organism. Ample evidence suggests that the various combinatorial fibroblast growth factor (FGF) and receptor signal transduction systems play prominent roles in injury repair and the remodeling of adult tissues in addition to embryonic development and regulation of metabolic homeostasis. In this review, we attempt to provide a brief update on our current understanding of the roles, the underlying mechanisms and clinical application of FGFs in tissue injury repair.

Exosomal let-7i-5p from three-dimensional cultured human umbilical cord mesenchymal stem cells inhibits fibroblast activation in silicosis through targeting TGFBR1

Silicosis of pulmonary fibrosis (PF) is related to long-term excessive inhalation of silica. The activation of fibroblasts into myofibroblasts is the main terminal effect leading to lung fibrosis, which is of great significance to the study of the occurrence and development of silicosis fibrosis and its prevention and treatment. Exosomes derived from human umbilical cord mesenchymal stem cells (hucMSC-Exos) are considered to be a potential therapy of silica-induced PF, however, their exact mechanism remains unknown. Therefore, this study aims to explore whether hucMSC-Exos affect the activation of fibroblasts to alleviate PF. In this study, a three-dimensional (3D) method was applied to culture hucMSCs and MRC-5 cells (human embryonic lung fibroblasts), and exosomes were isolated from serum-free media, identified by nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM) and Western blotting analysis. Then, the study used an animal model of silica-induced PF to observe the effects of hucMSC-Exos and MRC-5-Exos on activation of fibroblasts. In addition, the activation of fibroblasts was analyzed by Western blotting analysis, wound healing, and migration assay with the treatment of hucMSC-Exos and MRC-5-Exos in NIH-3T3 cells (mouse embryonic fibroblasts). Furthermore, differential expression of microRNAs (DE miRNAs) was measured between hucMSCs-Exos and MRC-5-Exos by high throughput sequence. HucMSC-Exos inhibited the activation of fibroblasts in mice and NIH-3T3 cells. Let-7i-5p was significantly up-regulated in hucMSCs-Exos compared to MRC-5-Exos, which was related to silica-induced PF. Let-7i-5p of hucMSCs-Exos was responsible for the activation of fibroblasts by targeting TGFBR1. Meanwhile, Smad3 was also an important role in the activation of fibroblasts. The study demonstrates that hucMSCs-Exos act as a mediator that transfers let-7i-5p to inhibit the activation of fibroblasts, which alleviates PF through the TGFBR1/Smad3 signaling pathway. The mechanism has potential value for the treatment of silica-induced PF.

Expression and function of fibroblast growth factor 1 in the hypertrophied ligamentum flavum of lumbar spinal stenosis

BACKGROUND

Fibrosis is one of the main pathologies caused by hypertrophy of the ligamentum flavum (LF), which leads to lumbar spinal stenosis (LSS). The fibroblast growth factor (FGF) family is a key mediator of fibrosis. However, acidic fibroblast growth factor (FGF-1) expression and function are not well understood in LF. This study sought to evaluate FGF-1 expression in the hypertrophied and non-hypertrophied human LF, and to investigate its function using primary human LF cell cultures.

METHODS

We obtained hypertrophied lumbar LF from LSS patients and non-hypertrophied lumbar LF from control patients during surgery. Immunohistochemistry and qPCR were performed to evaluate FGF-1 expression in LF tissue. The function of FGF-1 and transforming growth factor beta 1 (TGF-β1) was also investigated using primary LF cell culture. The effects on cell morphology and cell proliferation were examined using a crystal violet staining assay and MTT assay, respectively. Immunocytochemistry, western blotting, and qPCR were performed to evaluate the effect of FGF-1 on TGF-β1-induced myofibroblast differentiation and fibrosis.

RESULTS

Immunohistochemistry and qPCR showed higher FGF-1 expression in hypertrophied LF compared to control LF. Crystal violet staining and MTT assay revealed that FGF-1 decreases LF cell size and inhibits their proliferation in a dose-dependent manner, whereas TGF-β1 increases cell size and promotes proliferation. Immunocytochemistry and western blotting further demonstrated that TGF-β1 increases, while FGF-1 decreases, α-SMA expression in LF cells. Moreover, FGF-1 also caused downregulation of collagen type 1 and type 3 expression in LF cells.

CONCLUSION

FGF-1 is highly upregulated in the LF of LSS patients. Meanwhile, in vitro, FGF-1 exhibits antagonistic effects to TGF-β1 by inhibiting cell proliferation and decreasing LF cell size as well as the expression of fibrosis markers. These results suggest that FGF-1 has an anti-fibrotic role in the pathophysiology of LF hypertrophy.

Single-Cell RNA-Seq Analysis Reveals Macrophage Involved in the Progression of Human Intervertebral Disc Degeneration

Intervertebral disc degeneration (IDD) has been considered as the primary pathological mechanism that underlies low back pain. Understanding the molecular mechanisms underlying human IDD is imperative for making strategies to treat IDD-related diseases. Herein, we report the molecular programs, lineage progression patterns, and paths of cellular communications during the progression of IDD using single-cell RNA sequencing (scRNA-seq) on nucleus pulposus (NP) cells from patients with different grades of IDD undergoing discectomy. New subtypes of cells and cell-type-specific gene signatures of the metabolic homeostatic NP cells (Met NPC), adhesive NP cells (Adh NPC), inflammatory response NP cells (IR NPC), endoplasmic reticulum stress NP cells (ERS NPC), fibrocartilaginous NP cells (Fc NPC), and CD70 and CD82+ progenitor NP cells (Pro NPC) were identified. In the late stage of IDD, the IR NPC and Fc NPC account for a large proportion of NPC. Importantly, immune cells including macrophages, T cells, myeloid progenitors, and neutrophils were also identified, and further analysis showed that significant intercellular interaction between macrophages and Pro NPC occurred via MIF (macrophage migration inhibitory factor) and NF-kB signaling pathways during the progression of IDD. In addition, dynamic polarization of macrophage M1 and M2 cell subtypes was found in the progression of IDD, and gene set functional enrichment analysis suggested a significant role of the macrophage polarization in regulating cell metabolism, especially the Pro NPC. Finally, we found that the NP cells in the late degenerative stage were mainly composed of the cell types related to inflammatory and endoplasmic reticulum (ER) response, and fibrocartilaginous activity. Our results provided new insights into the identification of NP cell populations at single-cell resolution and at the relatively whole-transcriptome scale, accompanied by cellular communications between immune cells and NP cells, and discriminative markers in relation to specific cell subsets. These new findings present clues for effective and functional manipulation of human IDD-related bioremediation and healthcare.

Natural Product-Based Potential Therapeutic Interventions of Pulmonary Fibrosis

Pulmonary fibrosis (PF) is a disease-refractive lung condition with an increased rate of mortality. The potential factors causing PF include viral infections, radiation exposure, and toxic airborne chemicals. Idiopathic PF (IPF) is related to pneumonia affecting the elderly and is characterized by recurring scar formation in the lungs. An impaired wound healing process, defined by the dysregulated aggregation of extracellular matrix components, triggers fibrotic scar formation in the lungs. The potential pathogenesis includes oxidative stress, altered cell signaling, inflammation, etc. Nintedanib and pirfenidone have been approved with a conditional endorsement for the management of IPF. In addition, natural product-based treatment strategies have shown promising results in treating PF. In this study, we reviewed the recently published literature and discussed the potential uses of natural products, classified into three types-isolated active compounds, crude extracts of plants, and traditional medicine, consisting of mixtures of different plant products-in treating PF. These natural products are promising in the treatment of PF via inhibiting inflammation, oxidative stress, and endothelial mesenchymal transition, as well as affecting TGF-β-mediated cell signaling, etc. Based on the current review, we have revealed the signaling mechanisms of PF pathogenesis and the potential opportunities offered by natural product-based medicine in treating PF.

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.

Multipotent stromal cells: One name, multiple identities

Multipotent stromal cells (MSCs) are vital for development, maintenance, function, and regeneration of most tissues. They can differentiate along multiple connective lineages, but unlike most other stem/progenitor cells, they carry out various other functions while maintaining their developmental potential. MSCs function as damage sensors, respond to injury by fostering regeneration through secretion of trophic factors as well as extracellular matrix (ECM) molecules, and contribute to fibrotic reparative processes when regeneration fails. Tissue-specific MSC identity, fate(s), and function(s) are being resolved through fate mapping coupled with single cell "omics," providing unparalleled insights into the secret lives of tissue-resident MSCs.

FGF/FGFR signaling: From lung development to respiratory diseases

The fibroblast growth factor/fibroblast growth factor receptor (FGF/FGFR) signaling system regulates a variety of biological processes, including embryogenesis, angiogenesis, wound repair, tissue homeostasis, and cancer. It exerts these regulatory functions by controlling proliferation, differentiation, migration, survival, and metabolism of target cells. The morphological structure of the lung is a complex tree-like network for effective oxygen exchange, and the airway terminates in the middle and distal ends of many alveoli. FGF/FGFR signaling plays an important role in the pathophysiology of lung development and pathogenesis of various human respiratory diseases. Here, we mainly review recent advances in FGF/FGFR signaling during human lung development and respiratory diseases, including lung cancer, acute lung injury (ALI), pulmonary arterial hypertension (PAH), chronic obstructive pulmonary disease (COPD), asthma, and pulmonary fibrosis.

Taraxasterol inhibits TGF-β1-induced epithelial-to-mesenchymal transition in papillary thyroid cancer cells through regulating the Wnt/β-catenin signaling

Taraxasterol (TAR) is a kind of active compound extracted from dandelion and its molecular structure resembles steroid hormones. Recently, TAR has been reported to show an anti-tumor activity. However, the specific role of TAR in papillary thyroid cancer (PTC) has not been clarified. In this study, we investigated the effect of TAR on PTC cell migration, invasion and epithelial-to-mesenchymal transition (EMT) induced by TGF-β1. PTC cells were exposed to TGF-β1 (5 ng/mL) and then treated with different concentrations of TAR. We found that TAR showed no obvious cytotoxicity below 10 μg/mL but notably reduced migration and invasion of TGF-β1-treated PTC cells. Moreover, TAR treatment decreased MMP-2 and MMP-9 levels, and obviously affected the expression of EMT markers. We also observed that Wnt3a and β-catenin levels were significantly increased in TGF-β1-treated PTC cells while TAR inhibited these effects in a concentration-dependent manner. Additionally, activation of the Wnt pathway by LiCl attenuated the suppressive effect of TAR on TGF-β1-induced migration, invasion and EMT in PTC cells. Taken together, we highlighted that TAR could significantly suppress TGF-β1-regulated migration and invasion by reversing the EMT process via the Wnt/β-catenin pathway, suggesting that TAR may be a potential anti-cancer agent for PTC treatment.

Fibroblast growth factor receptor 3 activates a network of profibrotic signaling pathways to promote fibrosis in systemic sclerosis

Aberrant activation of fibroblasts with progressive deposition of extracellular matrix is a key feature of systemic sclerosis (SSc), a prototypical idiopathic fibrotic disease. Here, we demonstrate that the profibrotic cytokine transforming growth factor β selectively up-regulates fibroblast growth factor receptor 3 (FGFR3) and its ligand FGF9 to promote fibroblast activation and tissue fibrosis, leading to a prominent FGFR3 signature in the SSc skin. Transcriptome profiling, in silico analysis and functional experiments revealed that FGFR3 induces multiple profibrotic pathways including endothelin, interleukin-4, and connective tissue growth factor signaling mediated by transcription factor CREB (cAMP response element-binding protein). Inhibition of FGFR3 signaling by fibroblast-specific knockout of FGFR3 or FGF9 or pharmacological inhibition of FGFR3 blocked fibroblast activation and attenuated experimental skin fibrosis in mice. These findings characterize FGFR3 as an upstream regulator of a network of profibrotic mediators in SSc and as a potential target for the treatment of fibrosis.

A novel multikinase inhibitor SKLB-YTH-60 ameliorates inflammation and fibrosis in bleomycin-induced lung fibrosis mouse models

OBJECTIVES

Idiopathic pulmonary fibrosis (IPF) is marked by the excessive accumulation of extracellular matrix, which participates in a variety of chronic diseases or injuries and seriously threatens human health. Due to the side effects of clinical drugs, there is still a need to develop novel and less toxic drugs to treat pulmonary fibrosis.

MATERIALS AND METHODS

SKLB-YTH-60 was developed through computer-aided drug design, de novo synthesis and high-throughput screening. We employed the bleomycin (BLM)-induced lung fibrosis animal models and used TGF-β₁ to induce the epithelial-mesenchymal transition (EMT) of A549 cells in vitro. Meanwhile, the protein expression of collagen I and the α-smooth muscle actin (α-SMA), E-cadherin, p-FGFR1, p-PLCγ, p-Smad2/3 and p-Erk1/2 was detected by western blot.

RESULTS

YTH-60 has obvious anti-proliferative activity on fibroblasts and A549 cells. Moreover, YTH-60 could impair the EMT of A549 cells and suppressed fibrosis by inhibiting FGFR and TGF-β/Smad-dependent pathways. Intraperitoneal administration of preventive YTH-60 could significantly reduce the degree of fibrosis in mice and regulate the imbalance of the immune microenvironment. In addition, we observed that therapeutic YTH-60 treatment attenuated fibrotic changes in mice during the period of fibrosis. Importantly, YTH-60 has shown an acceptable oral bioavailability (F = 17.86%) and appropriate eliminated half-life time (T_1/2  = 8.03 hours).

CONCLUSIONS

Taken together, these preclinical evaluations suggested that YTH-60 could be a promising drug candidate for treating IPF.

Role of fibroblast growth factor signalling in hepatic fibrosis

Fibrotic remodelling is a highly conserved protective response to tissue injury and it is essential for the maintenance of structural and functional tissue integrity. Also hepatic fibrosis can be considered as a wound-healing response to liver injury, reflecting a balance between liver repair and scar formation. In contrast, pathological fibrosis corresponds to impaired wound healing. Usually, the liver regenerates after acute injury. However, if the damaging mechanisms persist, the liver reacts with progressive and uncontrolled accumulation of extracellular matrix proteins. Eventually, excessive fibrosis can lead to cirrhosis and hepatic failure. Furthermore, cirrhosis is the major risk factor for the development of hepatocellular cancer (HCC). Therefore, hepatic fibrosis is the most critical pathological factor that determines the morbidity and mortality of patients with chronic liver disease. Still, no effective anti-fibrogenic therapies exist, despite the very high medical need. The regulation of fibroblast growth factor (FGF) signalling is a prerequisite for adequate wound healing, repair and homeostasis in various tissues and organs. The FGF family comprises 22 proteins that can be classified into paracrine, intracrine and endocrine factors. Most FGFs signal through transmembrane tyrosine kinase FGF receptors (FGFRs). Although FGFRs are promising targets for the treatment of HCC, the expression and function of FGFR-ligands in hepatic fibrosis is still poorly understood. This review summarizes the latest advances in our understanding of FGF signalling in hepatic fibrosis. Furthermore, the potential of FGFs as targets for the treatment of hepatic fibrosis and remaining challenges for the field are discussed.

Tyrosine kinases in the pathogenesis of tissue fibrosis in systemic sclerosis and potential therapeutic role of their inhibition

Systemic sclerosis (SSc) is an idiopathic autoimmune disease with a heterogeneous clinical phenotype ranging from limited cutaneous involvement to rapidly progressive diffuse SSc. The most severe SSc clinical and pathologic manifestations result from an uncontrolled fibrotic process involving the skin and various internal organs. The molecular mechanisms responsible for the initiation and progression of the SSc fibrotic process have not been fully elucidated. Recently it has been suggested that tyrosine protein kinases play a role. The implicated kinases include receptor-activated tyrosine kinases and nonreceptor tyrosine kinases. The receptor kinases are activated following specific binding of growth factors (platelet-derived growth factor, fibroblast growth factor, or vascular endothelial growth factor). Other receptor kinases are the discoidin domain receptors activated by binding of various collagens, the ephrin receptors that are activated by ephrins and the angiopoetin-Tie-2s receptors. The nonreceptor tyrosine kinases c-Abl, Src, Janus, and STATs have also been shown to participate in SSc-associated tissue fibrosis. Currently, there are no effective disease-modifying therapies for SSc-associated tissue fibrosis. Therefore, extensive investigation has been conducted to examine whether tyrosine kinase inhibitors (TKIs) may exert antifibrotic effects. Here, we review the role of receptor and nonreceptor tyrosine kinases in the pathogenesis of the frequently progressive cutaneous and systemic fibrotic alterations in SSc, and the potential of TKIs as SSc disease-modifying antifibrotic therapeutic agents.

Anti-Fibrosis Effects of Magnesium Lithospermate B in Experimental Pulmonary Fibrosis: By Inhibiting TGF-βRI/Smad Signaling

Pulmonary fibrosis is a severe and irreversible interstitial pulmonary disease with high mortality and few treatments. Magnesium lithospermate B (MLB) is a hydrosoluble component of Salvia miltiorrhiza and has been reported to have antifibrotic effects in other forms of tissue fibrosis. In this research, we studied the effects of MLB on pulmonary fibrosis and the underlying mechanisms. Our results indicated that MLB treatment (50 mg/kg) for seven days could attenuate bleomycin (BLM)-induced pulmonary fibrosis by reducing the alveolar structure disruption and collagen deposition in the C57 mouse model. MLB was also found to inhibit transforming growth factor-beta (TGF-β)-stimulated myofibroblastic transdifferentiation of human lung fibroblast cell line (MRC-5) cells and collagen production by human type II alveolar epithelial cell line (A549) cells, mainly by decreasing the expression of TGF-β receptor I (TGF-βRI) and regulating the TGF-β/Smad pathway. Further studies confirmed that the molecular mechanisms of MLB in BLM-induced pulmonary fibrosis mice were similar to those observed in vitro. In summary, our results demonstrated that MLB could alleviate experimental pulmonary fibrosis both in vivo and in vitro, suggesting that MLB has great potential for pulmonary fibrosis treatment.

Cellular and molecular mechanisms in fibrosis

The activation of fibroblasts is required for physiological tissue remodelling such as wound healing. However, when the regulatory mechanisms are disrupted and fibroblasts remain persistently activated, the progressive deposition of extracellular matrix proteins leads to tissue fibrosis, which results in dysfunction or even loss of function of the affected organ. Although fibrosis has been recognized as a major cause of morbidity and mortality in modern societies, there are only few treatment options available that directly disrupt the release of extracellular matrix from fibroblasts. Intensive research in recent years, however, identified several pathways as core fibrotic mechanisms that are shared across different fibrotic diseases and organs. We discuss herein selection of those core pathways, especially downstream of the profibrotic TGF-β pathway, which are druggable and which may be transferable from bench to bedside.

Rejuveinix Shows a Favorable Clinical Safety Profile in Human Subjects and Exhibits Potent Preclinical Protective Activity in the Lipopolysaccharide-Galactosamine Mouse Model of Acute Respiratory Distress Syndrome and Multi-Organ Failure

Background: New treatment platforms that can prevent acute respiratory distress syndrome (ARDS) or reduce its mortality rate in high-risk coronavirus disease 2019 (COVID-19) patients, such as those with an underlying cancer, are urgently needed. Rejuveinix (RJX) is an intravenous formulation of anti-oxidants and anti-inflammatory agents. Its active ingredients include ascorbic acid, cyanocobalamin, thiamine hydrochloride, riboflavin 5' phosphate, niacinamide, pyridoxine hydrochloride, and calcium D-pantothenate. RJX is being developed as an anti-inflammatory and anti-oxidant treatment platform for patients with sepsis, including COVID-19 patients with viral sepsis and ARDS. Here, we report its clinical safety profile in a phase 1 clinical study (ClinicalTrials.gov Identifier: NCT03680105) and its potent protective activity in the lipopolysaccharide galactosamine (LPS-GalN) mouse model of ARDS. Methods: A phase 1, double-blind, placebo-controlled, randomized, two-part, ascending dose-escalation study was performed in participating 76 healthy volunteer human subjects in compliance with the ICH (E6) good clinical practice guidelines to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of RJX (Protocol No. RPI003; ClinicalTrials.gov Identifier: NCT03680105). The ability of RJX to prevent fatal shock, ARDS, and multi-organ failure was examined in the well-established LPS-GalN mouse model of sepsis and ARDS. Standard methods were employed for the statistical analysis of data in both studies. Findings: In the phase 1 clinical study, no participant developed serious adverse events (SAEs) or Grade 3-Grade 4 adverse events (AEs) or prematurely discontinued participation in the study. In the non-clinical study, RJX exhibited potent and dose-dependent protective activity, decreased the inflammatory cytokine responses (interleukin-6, tumor necrosis factor alpha, transforming growth factor beta), and improved survival in the LPS-GalN mouse model of sepsis and ARDS. Histopathological examinations showed that RJX attenuated the LPS-GalN induced acute lung injury (ALI) and pulmonary edema as well as liver damage. Conclusion: RJX showed a very favorable safety profile and tolerability in human subjects. It shows potential to favorably affect the clinical course of high-risk COVID-19 by preventing ARDS and its complications.

MiR-503 suppresses fibroblast activation and myofibroblast differentiation by targeting VEGFA and FGFR1 in silica-induced pulmonary fibrosis

Inhalation and deposition of crystalline silica particles in the lung can cause pulmonary fibrosis, then leading to silicosis. Given the paucity of effective drugs for silicosis, new insights for understanding the mechanisms of silicosis, including lung fibroblast activation and myofibroblast differentiation, are essential to explore therapeutic strategies. Our previous research showed that the up-regulation of miR-503 alleviated silica-induced pulmonary fibrosis in mice. In this study, we investigated whether miR-503 can regulate the TGF-β1-induced effects in lung fibroblasts. Mimic-based strategies aiming at up-regulating miR-503 were used to discuss the function of miR-503 in vivo and in vitro. We found that the expression level of miR-503 was decreased in fibroblasts stimulated by TGF-β1, and the up-regulation of miR-503 reduced the release of fibrotic factors and inhibited the migration and invasion abilities of fibroblasts. Combined with the up-regulation of miR-503 in a mouse model of silica-induced pulmonary fibrosis, we revealed that miR-503 mitigated the TGF-β1-induced effects in fibroblasts by regulating VEGFA and FGFR1 and then affecting the MAPK/ERK signalling pathway. In conclusion, miR-503 exerted protective roles in silica-induced pulmonary fibrosis and may represent a novel and potent candidate for therapeutic strategies in silicosis.

Blockade of Pan-Fibroblast Growth Factor Receptors Mediates Bidirectional Effects in Lung Fibrosis

FGFs (fibroblast growth factors) are major factors associated with the pathogenesis of pulmonary fibrosis. On the one hand, nintedanib, a tyrosine kinase inhibitor targeting several growth factor receptors, including the FGF receptor (FGFR), has been approved for the treatment of idiopathic pulmonary fibrosis. On the other hand, recent reports suggest that FGFs are required for epithelial recovery. In this study, we focused on FGF signaling to both fibroblasts and alveolar epithelial cells (AECs), and we examined the effect of a pan-FGFR blocker on experimental pulmonary fibrosis in mice. The effects of BGJ398, a pan-FGFR inhibitor, on the migration and proliferation of fibroblasts and AECs were assessed using Transwell migration or [³H]thymidine incorporation assays. The expression of FGFR was analyzed using IB or flow cytometry. We also investigated the effect of BGJ398 on pulmonary fibrosis induced by bleomycin in mice. Both lung fibroblasts and AECs expressed FGFRs. BGJ398 significantly inhibited the proliferation and migration of lung fibroblasts stimulated with FGF2. BGJ398 also reduced the proliferation of AECs in response to FGF2. Although the administration of BGJ398 ameliorated pulmonary fibrosis in bleomycin-treated mice, it increased mortality resulting from alveolar injury and inhibition of AEC regeneration. These data suggest that the total inhibition of FGFR signaling can suppress lung fibrosis by inhibiting fibroblast activities, although alveolar injury is simultaneously caused.

FGF/FGFR signaling in health and disease

Growing evidences suggest that the fibroblast growth factor/FGF receptor (FGF/FGFR) signaling has crucial roles in a multitude of processes during embryonic development and adult homeostasis by regulating cellular lineage commitment, differentiation, proliferation, and apoptosis of various types of cells. In this review, we provide a comprehensive overview of the current understanding of FGF signaling and its roles in organ development, injury repair, and the pathophysiology of spectrum of diseases, which is a consequence of FGF signaling dysregulation, including cancers and chronic kidney disease (CKD). In this context, the agonists and antagonists for FGF-FGFRs might have therapeutic benefits in multiple systems.

Dualism of FGF and TGF-β Signaling in Heterogeneous Cancer-Associated Fibroblast Activation with ETV1 as a Critical Determinant

Heterogeneity of cancer-associated fibroblasts (CAFs) can result from activation of distinct signaling pathways. We show that in primary human dermal fibroblasts (HDFs), fibroblast growth factor (FGF) and transforming growth factor β (TGF-β) signaling oppositely modulate multiple CAF effector genes. Genetic abrogation or pharmacological inhibition of either pathway results in induction of genes responsive to the other, with the ETV1 transcription factor mediating the FGF effects. Duality of FGF/TGF-β signaling and differential ETV1 expression occur in multiple CAF strains and fibroblasts of desmoplastic versus non-desmoplastic skin squamous cell carcinomas (SCCs). Functionally, HDFs with opposite TGF-β versus FGF modulation converge on promoting cancer cell proliferation. However, HDFs with increased TGF-β signaling enhance invasive properties and epithelial-mesenchymal transition (EMT) of SCC cells, whereas HDFs with increased FGF signaling promote macrophage infiltration. The findings point to a duality of FGF versus TGF-β signaling in distinct CAF populations that promote cancer development through modulation of different processes.

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FGF and TGF-β signaling exert opposite control over multiple CAF effector genes

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ETV1 transcription factor mediates FGF effects and suppresses those of TGF-β

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Modulation of either pathway leads to different tumor-promoting CAF populations

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TGF-β-activated CAFs promote EMT, but FGF-activated CAFs increase inflammation

Identification and activity of the functional complex between hnRNPL and the pseudoexfoliation syndrome-associated lncRNA, LOXL1-AS1

Individuals with pseudoexfoliation (PEX) syndrome exhibit various connective tissue pathologies associated with dysregulated extracellular matrix homeostasis. PEX glaucoma is a common, aggressive form of open-angle glaucoma resulting from the deposition of fibrillary material in the conventional outflow pathway. However, the molecular mechanisms that drive pathogenesis and genetic risk remain poorly understood. PEX glaucoma-associated single-nucleotide polymorphisms are located in and affect activity of the promoter of LOXL1-AS1, a long non-coding RNA (lncRNA). Nuclear and non-nuclear lncRNAs regulate a host of biological processes, and when dysregulated, contribute to disease. Here we report that LOXL1-AS1 localizes to the nucleus where it selectively binds to the mRNA processing protein, heterogeneous nuclear ribonucleoprotein-L (hnRNPL). Both components of this complex are critical for the regulation of global gene expression in ocular cells, making LOXL1-AS1 a prime target for investigation in PEX syndrome and glaucoma.

Bi-directional communication: Conversations between fibroblasts and immune cells in systemic sclerosis

Systemic Sclerosis (SSc) is an autoimmune idiopathic connective tissue disease, characterized by aberrant fibro-proliferative and inflammatory responses, causing fibrosis of multiple organs. In recent years the interactions between innate and adaptive immune cells with resident fibroblasts have been uncovered. Cross-talk between immune and stromal cells mediates activation of stromal cells to myofibroblasts; key cells in the pathophysiology of fibrosis. These cells and their cytokines appear to mediate their effects in both a paracrine and autocrine fashion. This review examines the role of innate and adaptive immune cells in SSc, focusing on recent advances that have illuminated our understanding of ongoing bi-directional communication between immune and stromal cells. Finally, we appraise current and future therapies and how these may be useful in a disease that currently has no specific disease modifying treatment.

Fibroblast Growth Factor (FGF) Signaling Protects Against Acute Pancreatitis-Induced Damage by Modulating Inflammatory Responses

BACKGROUND Acute pancreatitis (AP) is a symptom of sudden pancreas inflammation, which causes patients severe suffering. In general, fibroblast growth factor (FGF) levels are increased and amylase and lipase activities are elevated during AP pathogenesis, but protein concentration are low. However, the mechanism through which FGF signaling regulates AP pathogenesis remains elusive. MATERIAL AND METHODS The concentrations of PGE2, TNF-alpha, sCRP, FGF1, and FGF2 in the serum samples of the AP group and healthy control group were detected by enzyme-linked immunosorbent assay. In addition, IkappaBalpha and p-IkappaBalpha levels were analyzed in the serum samples. Subsequently, the AP rat model was established, and FGF1, FGF2, anti-FGF1, and anti-FGF2 antibodies and Bay11-7082 were injected into AP rats. TNF-alpha, PAI-1 JNK, p-JNK, IkappaBalpha, and p-IkappaBalpha levels were also examined. RESULTS Results showed that levels of PGE2, TNF-alpha, sCRP, p-IkappaBalpha, FGF1, and FGF2, as well as amylase and lipase activity were increased in patients with AP compared with those in healthy people. In addition, protein concentrations were lower in patients with AP than in the healthy group. Activation of FGF signaling by injecting FGF1 or FGF2 also inhibited AP-induced inflammation response in the pancreas and increased amylase and lipase activities, as well as protein concentration. However, the injection of FGF1 and FGF2 antibodies accelerated AP-mediated inflammation responses in the serum. In addition, Bay11-7082 injection inhibited AP activation of inflammation response and amylase and lipase activities. Protein concentration were also increased in AP rats. CONCLUSIONS FGF signaling protects against AP-mediated damage by inhibition of AP-activating inflammatory responses.

Inguinal Ring RNA Sequencing Reveals Downregulation of Muscular Genes Related to Scrotal Hernia in Pigs

Scrotal hernias (SH) are common congenital defects in commercial pigs, characterized by the presence of abdominal contents in the scrotal sac, leading to considerable production and animal welfare losses. Since the etiology of SH remains obscure, we aimed to identify the biological and genetic mechanisms involved in its occurrence through the whole transcriptome analysis of SH affected and unaffected pigs’ inguinal rings. From the 22,452 genes annotated in the pig reference genome, 13,498 were expressed in the inguinal canal tissue. Of those, 703 genes were differentially expressed (DE, FDR < 0.05) between the two groups analyzed being, respectively, 209 genes upregulated and 494 downregulated in the SH-affected group. Thirty-seven significantly overrepresented GO terms related to SH were enriched, and the most relevant biological processes were muscular system, cell differentiation, sarcome reorganization, and myofibril assembly. The calcium signaling, hypertrophic cardiomyopathy, dilated cardiomyopathy, and cardiac muscle contraction were the major pathways possibly involved in the occurrence of the scrotal hernias. The expression profile of the DE genes was associated with the reduction of smooth muscle differentiation, followed by low calcium content in the cell, which could lead to a decreased apoptosis ratio and diminished muscle contraction of the inguinal canal region. We have demonstrated that genes involved with musculature are closely linked to the physiological imbalance predisposing to scrotal hernia. According to our study, the genes MYBPC1, BOK, SLC25A4, SLC8A3, DES, TPM2, MAP1CL3C, and FGF1 were considered strong candidates for future evaluation.

The Tyrosine Kinase Inhibitor TAS-115 Attenuates Bleomycin-induced Lung Fibrosis in Mice

The signaling pathways of growth factors, including platelet-derived growth factor, can be considered specific targets for overcoming the poor prognosis of idiopathic pulmonary fibrosis. Nintedanib, the recently approved multiple kinase inhibitor, has shown promising antifibrotic effects in patients with idiopathic pulmonary fibrosis; however, its efficacy is still limited, and in some cases, treatment discontinuation is necessary owing to toxicities such as gastrointestinal disorders. Therefore, more effective agents with less toxicity are still needed. TAS-115 is a novel multiple tyrosine kinase inhibitor that preferably targets platelet-derived growth factor receptor (PDGFR), vascular endothelial growth factor receptor, and c-FMS in addition to other molecules. In this study, we evaluated the antifibrotic effect of TAS-115 on pulmonary fibrosis in vitro and in vivo. TAS-115 inhibited the phosphorylation of PDGFR on human lung fibroblast cell line MRC-5 cells and suppressed their platelet-derived growth factor-induced proliferation and migration. Furthermore, TAS-115 inhibited the phosphorylation of c-FMS, a receptor of macrophage colony-stimulating factor, in murine bone marrow-derived macrophages and decreased the production of CCL2, another key molecule for inducing pulmonary fibrosis, under the stimulation of macrophage colony-stimulating factor. Importantly, the inhibitory effects of TAS-115 on both PDGFR and c-FMS were 3- to 10-fold higher than those of nintedanib. In a mouse model of bleomycin-induced pulmonary fibrosis, TAS-115 significantly inhibited the development of pulmonary fibrosis and the collagen deposition in bleomycin-treated lungs. These data suggest that strong inhibition of PDGFR and c-FMS by TAS-115 may be a promising strategy for overcoming the intractable pathogenesis of pulmonary fibrosis.

Angiogenic signaling in the lungs of a metabolically suppressed hibernating mammal (Ictidomys tridecemlineatus)

To conserve energy in times of limited resource availability, particularly during cold winters, hibernators suppress even the most basic of physiologic processes. Breathing rates decrease from 40 breaths/minute to less than 1 breath/min as they decrease body temperature from 37 °C to ambient. Nevertheless, after months of hibernation, these incredible mammals emerge from torpor unscathed. This study was conducted to better understand the protective and possibly anti-inflammatory adaptations that hibernator lungs may use to prevent damage associated with entering and emerging from natural torpor. We postulated that the differential protein expression of soluble protein receptors (decoy receptors that sequester soluble ligands to inhibit signal transduction) would help identify inhibited inflammatory signaling pathways in metabolically suppressed lungs. Instead, the only two soluble receptors that responded to torpor were sVEGFR1 and sVEGFR2, two receptors whose full-length forms are bound by VEGF-A to regulate endothelial cell function and angiogenesis. Decreased sVEGFR1/2 correlated with increased total VEGFR2 protein levels. Maintained or increased levels of key γ-secretase subunits suggested that decreased sVEGFR1/2 protein levels were not due to decreased levels of intramembrane cleavage complex subunits. VEGF-A protein levels did not change, suggesting that hibernators may regulate VEGFR1/2 signaling at the level of the receptor instead of increasing relative ligand abundance. A panel of angiogenic factors used to identify biomarkers of angiogenesis showed a decrease in FGF-1 and an increase in BMP-9. Torpid lungs may use VEGF and BMP-9 signaling to balance angiogenesis and vascular stability, possibly through the activation of SMAD signaling for adaptive tissue remodeling.