Noncanonical Wnt Signaling Promotes Myofibroblast Differentiation in Pulmonary Fibrosis

Idiopathic pulmonary fibrosis microenvironment: Novel mechanisms and research directions

Idiopathic Pulmonary Fibrosis (IPF) is a progressive interstitial lung disease marked by increasing dyspnea and respiratory failure. The underlying mechanisms remain poorly understood, given the complexity of its pathogenesis. This review investigates the microenvironment of IPF to identify novel mechanisms and therapeutic avenues. Studies have revealed that various cell types, including alveolar epithelial cells, fibroblasts, myofibroblasts, and immune cells, are integral to disease progression, engaging in cellular stress responses and inflammatory regulation via signaling pathways such as TGF-β, Wnt, mTOR, and ROS. Non-coding RNAs, particularly miRNAs, are critical in IPF and may serve as diagnostic and prognostic biomarkers. Regarding treatment, mesenchymal stem cells (MSCs) and their extracellular vesicles (EVs) or non-vesicular derivatives offer promise by modulating immune responses, enhancing tissue repair, and inhibiting fibrosis. Additionally, alterations in the lung microbiota are increasingly recognized as a contributing factor to IPF progression, offering fresh insights into potential treatments. Despite the encouraging results of MSC-based therapies, the precise mechanisms and clinical applications remain subjects of ongoing research. This review emphasizes the significance of the IPF microenvironment and highlights the need for further exploration to develop effective therapies that could enhance patient outcomes.

The role of cyclic adenosine monophosphate (cAMP) in pathophysiology of fibrosis

Fibrosis, the excessive production and disorganised deposition of extracellular matrix proteins, can occur in any organ system, disrupting functionality and causing fatality. The number, efficacy and safety of antifibrotic drugs are incredibly limited. Therapeutics which elevate intracellular cyclic adenosine monophosphate (cAMP) offer a potential solution. In this review, we present the signalling mechanisms involved in fibrosis pathophysiology, how cAMP and its effectors might interact with these pathways, and the current preclinical and clinical efforts in this field. cAMP elevating agents have the potential to be future antifibrotic drug candidates, but further studies are required, particularly to develop tissue specific therapeutics.

Calcaratarin D, A Labdane Diterpenoid, Attenuates Bleomycin-Induced Pulmonary Fibrosis by Blocking Wnt/β-Catenin Signaling Pathway

Idiopathic pulmonary fibrosis (IPF) is one of the most common interstitial lung diseases with a high mortality rate. Calcaratarin D (CalD), a labdane diterpenoid, has been shown to possess anti-inflammatory properties. The present study evaluated the therapeutic potential of CalD in pulmonary fibrosis. A single dose of bleomycin (BLM, 2.5mg/kg) was instilled intratracheally in mice for up to 21 days to develop lung fibrosis. Oral CalD (50mg/kg) reduced BLM-induced inflammatory cell infiltration, especially pro-fibrotic Arg1-expressing interstitial macrophages in the bronchoalveolar lavage fluid. During the late fibrotic phase, CalD decreased BLM-induced mortality and body weight loss. In addition, CalD ameliorated lung histopathology, reduced collagen deposition and mucus hypersecretion, and improved lung functions in BLM-exposed mice. Furthermore, CalD modulated the levels of pro-inflammatory cytokines, chemokines, and growth factors in BAL fluid and lung tissues. In mouse lungs, BLM selectively upregulated Wnt10A level and promoted β-catenin nuclear translocation. CalD not only blocked Wnt10A/β-catenin signaling pathway but also reduced pro-fibrotic markers such as collagens, α-SMA and FHL2. In normal human lung fibroblasts, CalD inhibited TGF-β1-stimulated pro-fibrotic markers and Wnt/β-catenin signaling pathway by reducing Wnt10A production, upregulating endogenous Wnt antagonist DKK1 level, dephosphorylating Wnt ligand co-receptor LRP6, and preventing β-catenin and YAP/TAZ nuclear translocation. The antifibrotic action of CalD was shown to be dependent on its α,β-unsaturated γ-butyrolactone structure that is essential for CalD to form covalent interaction with cellular protein targets. Our results imply that CalD could be a novel antifibrotic agent for IPF, acting through blockade of the Wnt/β-catenin signaling pathway.

Inhibition of sphingosine-1-phosphate receptor-2 attenuates idiopathic pulmonary fibrosis by preventing its binding to dapper1 in bronchial epithelial cells

BACKGROUND AND PURPOSE

Activation of the sphingosine-1-phosphate receptor-2 (S1P2 receptor) promotes idiopathic pulmonary fibrosis (IPF). However, the mechanisms associated with IPF development via S1P2 receptor signalling are poorly understood and no S1P2 receptor antagonists have been approved for clinical use.

EXPERIMENTAL APPROACH

Western blotting and immunohistochemical assays analysed inflammatory factors and epithelial-mesenchymal transition (EMT) markers. Co-immunoprecipitation and immunofluorescence analysed the binding of S1P2 receptor to dapper1 (Dpr1) and cyclic AMP response-binding protein 1 (CREB1). X-ray-based computed tomography diagnosed IPF in bleomycin (BLM)-treated mice. Barometric whole-body plethysmography tested pulmonary function of mice. Masson's trichrome and Sirius red staining analysed extracellular matrix deposition. Enzyme-linked immunosorbent assays analysed inflammatory factors and hydroxyproline.

KEY RESULTS

Activation of S1P2 receptors promoted IPF through the binding of S1P2 receptor to Dpr1, decreasing dishevelled (Dvl) degradation to accumulate β-catenin. The β-catenin accumulated in the nucleus, upregulating its target genes by binding to T-cell factor/lymphoid enhancer factor. The binding of S1P2 receptor to Dpr1 also led to S1P2 receptor translocation to the nucleus, where it promoted EMT by activating CREB1. BLM-induced IPF in mice was characterised by activated-S1P2 receptor signalling. Inhibition of S1P2 receptor prevented the binding of S1P2 receptor to Dpr1, resulting in decreased β-catenin accumulation and blocking nuclear translocation of S1P2 receptor. The S1P2 receptor antagonist S118 was more effective than pirfenidone in attenuating IPF through anti-inflammatory, anti-fibrosis, and anti-EMT effects.

CONCLUSIONS AND IMPLICATIONS

Activation of S1P2 receptors promotes IPF through the binding of S1P2 receptor to Dpr1 and the nuclear translocation of S1P2 receptor to activate CREB1. Thus, the S1P2 receptor antagonist S118 has potential clinical application in attenuating IPF.

Deciphering the interplay: circulating cell-free DNA, signaling pathways, and disease progression in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a lung disease with an unknown etiology and a short survival rate. There is no accurate method of early diagnosis, and it involves computed tomography (CT) or lung biopsy. Since diagnostic methods are not accurate due to their similarity to other lung pathologies, discovering new biomarkers is a key issue for diagnosticians. Currently, the use of ccf-DNA (circulating cell-free deoxyribonucleic acid) is an important focus due to its association with IPF-induced alterations in metabolic pathways, such as amino acid metabolism, energy metabolism, and lipid metabolism pathways. Other biomarkers associated with metabolic changes have been found, and they are related to changes in type II/type I alveolar epithelial cells (AECs I/II), changes in extracellular matrix (ECM), and inflammatory processes. Currently, IPF pathogenetic treatment remains unknown, and the mortality rates are increasing, and the patients are diagnosed at a late stage. Signaling pathways and metabolic dysfunction have a significant role in the disease occurrence, particularly the transforming growth factor-β (TGF-β) signaling pathway, which plays an essential role. TGF-β, Wnt, Hedgehog (Hh), and integrin signaling are the main drivers of fibrosis. These pathways activate the transformation of fibroblasts into myofibroblasts, extracellular matrix (ECM) deposition, and tissue remodeling fibrosis. Therapy targeting diverse signaling pathways to slow disease progression is crucial in the treatment of IPF. Two antifibrotic medications, including pirfenidone and nintedanib, are Food and Drug Administration (FDA)-approved for treatment. ccf-DNA could become a new biomarker for IPF diagnosis to detect the disease at the early stage, while FDA-approved therapies could help to prevent late conditions from forming and decrease mortality rates.

Transcriptional enhancers in human neuronal differentiation provide clues to neuronal disorders

Genome-wide association studies (GWASs) have identified thousands of variants associated with complex phenotypes, including neuropsychiatric disorders. To better understand their pathogenesis, it is necessary to identify the functional roles of these variants, which are largely located in non-coding DNA regions. Here, we employ a human mesencephalic neuronal cell differentiation model, LUHMES, with sensitive and high-resolution methods to discover enhancers (NET-CAGE), perform DNA conformation analysis (Capture Hi-C) to link enhancers to their target genes, and finally validate selected interactions. We expand the number of known enhancers active in differentiating human LUHMES neurons to 47,350, and find overlap with GWAS variants for Parkinson's disease and schizophrenia. Our findings reveal a fine-tuned regulation of human neuronal differentiation, even between adjacent developmental stages; provide a valuable resource for further studies on neuronal development, regulation, and disorders; and emphasize the importance of exploring the vast regulatory potential of non-coding DNA and enhancers.

CCN2 mediates fibroblast-macrophage interaction in knee arthrofibrosis based on single-cell RNA-seq analysis

Knee arthrofibrosis, characterized by excessive matrix protein production and deposition, substantially impairs basic daily functions, causing considerable distress and financial burden. However, the underlying pathomechanisms remain unclear. Here, we characterized the heterogeneous cell populations and cellular pathways by combination of flow cytometry and single-cell RNA-seq analysis of synovial tissues from six patients with or without knee arthrofibrosis. Increased macrophages and fibroblasts were observed with decreased numbers of fibroblast-like synoviocytes, endothelial cells, vascular smooth muscle cells, and T cells in the arthrofibrosis group compared with negative controls. Notably, fibroblasts were discovered to interact with macrophages, and lead to fibrosis through TGF-β pathway induced CCN2 expression in fibroblasts. CCN2 was demonstrated to be required for fibroblast pro-fibrotic functions (activation, proliferation, and migration) through TGFBR/SMAD pathway. The expression of CCN2 was positively correlated with the collagen volume and TGF-β expression and negatively associated with patient-reported outcome measures in another cohort of patients with knee arthrofibrosis. Our study reveals the role of CCN2 in the fibroblast-macrophage interaction through TGF-β pathway which might help to shed light on CCN2 as a potential biomarker.

Genome-wide CRISPR/Cas9 screening identifies key profibrotic regulators of TGF-β1-induced epithelial-mesenchymal transformation and pulmonary fibrosis

Background

The idiopathic pulmonary fibrosis (IPF) is a progressive and lethal interstitial lung disease with high morbidity and mortality. IPF is characterized by excessive extracellular matrix accumulation (ECM) and epithelial-mesenchymal transformation (EMT). To date, few anti-fibrotic therapeutics are available to reverse the progression of pulmonary fibrosis, and it is important to explore new profibrotic molecular regulators mediating EMT and pulmonary fibrosis.

Methods

Based on our model of TGF-β1-induced EMT in BEAS-2B cells, we performed the genome-wide CRISPR/Cas9 knockout (GeCKO) screening technique, pathway and functional enrichment analysis, loss-of-function experiment, as well as other experimental techniques to comprehensively investigate profibrotic regulators contributing to EMT and the pathogenesis of pulmonary fibrosis.

Results

Utilizing the GeCKO library screening, we identified 76 top molecular regulators. Ten candidate genes were subsequently confirmed by integrating the high-throughput data with findings from pathway and functional enrichment analysis. Among the candidate genes, knockout of COL20A1 and COL27A1 led to decreased mRNA expression of ECM components (Fibronectin and Collagen-I), as well as an increased rate of cell apoptosis. The mRNA expression of Collagen-I, together with the cell viability and migration, were inhibited when knocking out the WNT11. In addition, a decrease in the protein deposition of ECM components was observed by suppressing the expression of COL20A1, COL27A1, and WNT11.

Conclusion

Our study demonstrates that the COL20A1, COL27A1, and WNT11 serve as key profibrotic regulators of EMT. Gaining understanding and insights into these key profibrotic regulators of EMT paves the way for the discovery of new therapeutic targets against the onset and progression of IPF.

Inhalable Carbonyl Sulfide Donor-Hybridized Selective Phosphodiesterase 10A Inhibitor for Treating Idiopathic Pulmonary Fibrosis by Inhibiting Tumor Growth Factor-β Signaling and Activating the cAMP/Protein Kinase A/cAMP Response Element-Binding Protein (CREB)/p53 Axis

Idiopathic pulmonary fibrosis (IPF) is a debilitating, incurable, and life-threatening disease that lacks effective therapy. The overexpression of phosphodiesterase 10A (PDE10A) plays a vital role in pulmonary fibrosis (PF). However, the impact of selective PDE10A inhibitors on the tumor growth factor-β (TGF-β)/small mother against decapentaplegic (Smad) signaling pathway remains unclear. Herein, we have exploited a novel carbonyl sulfide (COS)/hydrogen sulfide (H2S)-donor hybrid PDE10A inhibitor called COS-2080 with a well-defined mechanism of H2S-releasing action. It exhibited highly potent inhibitory activity against PDE10A and excellent PDE subfamily selectivity. Moreover, COS-2080 demonstrated significant antifibrotic effects by inhibiting cell proliferation and mitigating fibroblast-to-myofibroblast transition (FMT). A dry powder inhalation formulation called COS-2080-DPI has been developed using the ultrasonic spray freeze drying (USFD) technique, demonstrating significant antifibrotic efficacy in mice with bleomycin-induced PF at a dosage approximately 600 times lower than pirfenidone. This remarkable antifibrotic efficacy of COS-2080 on TGF-β1-induced FMT could be primarily attributed to its inhibition of the Smad2/Smad3 phosphorylation. Moreover, COS-2080 effectively attenuated fibrosis in MRC-5 cells by activating the cAMP/protein kinase A (PKA)/CREB pathway and potentially increasing levels of p53 protein. Our findings suggest that effective inhibition of PDE10A potentially confers a protective effect on FMT in PF by impeding TGF-β signaling and activating the cAMP/PKA/CREB/p53 axis.

CasRx-based Wnt activation promotes alveolar regeneration while ameliorating pulmonary fibrosis in a mouse model of lung injury

Wnt/β-catenin signaling is an attractive target for regenerative medicine. A powerful driver of stem cell activity and hence tissue regeneration, Wnt signaling can promote fibroblast proliferation and activation, leading to fibrosis, while prolonged Wnt signaling is potentially carcinogenic. Thus, to harness its therapeutic potential, the activation of Wnt signaling must be transient, reversible, and tissue specific. In the lung, Wnt signaling is essential for alveolar stem cell activity and alveolar regeneration, which is impaired in lung fibrosis. Activation of Wnt/β-catenin signaling in lung epithelium may have anti-fibrotic effects. Here, we used intratracheal adeno-associated virus 6 injection to selectively deliver CasRx into the lung epithelium, where it reversibly activates Wnt signaling by simultaneously degrading mRNAs encoding Axin1 and Axin2, negative regulators of Wnt/β-catenin signaling. Interestingly, CasRx-mediated Wnt activation specifically in lung epithelium not only promotes alveolar type II cell proliferation and alveolar regeneration but also inhibits lung fibrosis resulted from bleomycin-induced injury, relevant in both preventive and therapeutic settings. Our study offers an attractive strategy for treating pulmonary fibrosis, with general implications for regenerative medicine.

Pulmonary fibrosis: pathogenesis and therapeutic strategies

Pulmonary fibrosis (PF) is a chronic and progressive lung disease characterized by extensive alterations of cellular fate and function and excessive accumulation of extracellular matrix, leading to lung tissue scarring and impaired respiratory function. Although our understanding of its pathogenesis has increased, effective treatments remain scarce, and fibrotic progression is a major cause of mortality. Recent research has identified various etiological factors, including genetic predispositions, environmental exposures, and lifestyle factors, which contribute to the onset and progression of PF. Nonetheless, the precise mechanisms by which these factors interact to drive fibrosis are not yet fully elucidated. This review thoroughly examines the diverse etiological factors, cellular and molecular mechanisms, and key signaling pathways involved in PF, such as TGF-β, WNT/β-catenin, and PI3K/Akt/mTOR. It also discusses current therapeutic strategies, including antifibrotic agents like pirfenidone and nintedanib, and explores emerging treatments targeting fibrosis and cellular senescence. Emphasizing the need for omni-target approaches to overcome the limitations of current therapies, this review integrates recent findings to enhance our understanding of PF and contribute to the development of more effective prevention and management strategies, ultimately improving patient outcomes.

Activation of Wnt/β-catenin signaling promotes immune evasion via the β-catenin/IKZF1/CCL5 axis in hepatocellular carcinoma

Immune checkpoint therapy (ICT) has been shown to produce durable responses in various cancer patients. However, its efficacy is notably limited in hepatocellular carcinoma (HCC), with only a small percentage of patients responding positively to treatment. The mechanism underlying resistance to ICT in HCC remains poorly understood. Here, we showed that combination treatment of ICG-001, an inhibitor of the Wnt/β-catenin signaling pathway, with anti-PD-1 antibody effectively suppresses tumor growth and promotes the infiltration of immune cells such as DCs and CD8+ T cells in the tumor microenvironment (TME). By inhibiting the activity of β-catenin and blocking its binding to the transcription factor IKAROS family zinc finger 1 (IKZF1), ICG-001 upregulated the expression of CCL5. Moreover, IKZF1 regulated the activity of the CCL5 promoter and its endogenous expression. Through inhibition of the WNT/β-catenin signaling pathway, upregulation of the expression of CCL5 was achieved, which subsequently recruited more DCs into the TME via C-C motif chemokine receptor 5 (CCR5). This, in turn, resulted in an increase in the infiltration of CD8+ T cells in the TME, thereby enhancing the antitumor immune response. Analysis of a tissue microarray derived from HCC patient samples revealed a positive correlation between survival rate and prognosis and the expression levels of CCL5/CD8. In conclusion, our findings suggest that combined application of ICG-001 and anti-PD-1 antibody exhibits significantly enhanced antitumor efficacy. Hence, combining a WNT/β-catenin signaling pathway inhibitor with anti-PD-1 therapy may be a promising treatment strategy for patients with HCC.

Biliary fibrosis is an important but neglected pathological feature in hepatobiliary disorders: from molecular mechanisms to clinical implications

Fibrosis resulting from pathological repair secondary to recurrent or persistent tissue damage often leads to organ failure and mortality. Biliary fibrosis is a crucial but easily neglected pathological feature in hepatobiliary disorders, which may promote the development and progression of benign and malignant biliary diseases through pathological healing mechanisms secondary to biliary tract injuries. Elucidating the etiology and pathogenesis of biliary fibrosis is beneficial to the prevention and treatment of biliary diseases. In this review, we emphasized the importance of biliary fibrosis in cholangiopathies and summarized the clinical manifestations, epidemiology, and aberrant cellular composition involving the biliary ductules, cholangiocytes, immune system, fibroblasts, and the microbiome. We also focused on pivotal signaling pathways and offered insights into ongoing clinical trials and proposing a strategic approach for managing biliary fibrosis-related cholangiopathies. This review will offer a comprehensive perspective on biliary fibrosis and provide an important reference for future mechanism research and innovative therapy to prevent or reverse fibrosis.

Non-immune factors cause prolonged myofibroblast phenotype in implanted synthetic heart valve scaffolds

The clinical application of heart valve scaffolds is hindered by complications associated with the activation of valvular interstitial cell-like (VIC-like) cells and their transdifferentiation into myofibroblasts. This study aimed to examine several molecular pathway(s) that may trigger the overactive myofibroblast phenotypes in the implanted scaffolds. So, we investigated the influence of three molecular pathways - macrophage-induced inflammation, the TGF-β1-SMAD2, and WNT/β-catenin β on VIC-like cells during tissue engineering of heart valve scaffolds. We implanted electrospun heart valve scaffolds in adult sheep for up to 6 months in the right ventricular outflow tract (RVOT) and analyzed biomolecular (gene and protein) expression associated with the above three pathways by the scaffold infiltrating cells. The results showed a gradual increase in gene and protein expression of markers related to the activation of VIC-like cells and the myofibroblast phenotypes over 6 months of scaffold implantation. Conversely, there was a gradual increase in macrophage activity for the first three months after scaffold implantation. However, a decrease in macrophage activity from three to six months of scaffold tissue engineering suggested that immunological signal factors were not the primary cause of myofibroblast phenotype. Similarly, the gene and protein expression of factors associated with the TGF-β1-SMAD2 pathway in the cells increased in the first three months but declined in the next three months. Contrastingly, the gene and protein expression of factors associated with the WNT/β-catenin pathway increased significantly over the six-month study. Thus, the WNT/β-catenin pathway could be the predominant mechanism in activating VIC-like cells and subsequent myofibroblast phenotype.

Targeting CEBPA to restore cellular identity and tissue homeostasis in pulmonary fibrosis

Fibrosis in the lung is thought to be driven by epithelial cell dysfunction and aberrant cell-cell interactions. Unveiling the molecular mechanisms of cellular plasticity and cell-cell interactions is imperative to elucidating lung regenerative capacity and aberrant repair in pulmonary fibrosis. By mining publicly available RNA-Seq data sets, we identified loss of CCAAT enhancer-binding protein alpha (CEBPA) as a candidate contributor to idiopathic pulmonary fibrosis (IPF). We used conditional KO mice, scRNA-Seq, lung organoids, small-molecule inhibition, and potentially novel gene manipulation methods to investigate the role of CEBPA in lung fibrosis and repair. Long-term (6 months or more) of Cebpa loss in AT2 cells caused spontaneous fibrosis and increased susceptibility to bleomycin-induced fibrosis. Cebpa knockout (KO) in these mice significantly decreased AT2 cell numbers in the lung and reduced expression of surfactant homeostasis genes, while increasing inflammatory cell recruitment as well as upregulating S100a8/a9 in AT2 cells. In vivo treatment with an S100A8/A9 inhibitor alleviated experimental lung fibrosis. Restoring CEBPA expression in lung organoids ex vivo and during experimental lung fibrosis in vivo rescued CEBPA deficiency-mediated phenotypes. Our study establishes a direct mechanistic link between CEBPA repression, impaired AT2 cell identity, disrupted tissue homeostasis, and lung fibrosis.

Profibrotic Subsets of SPP1+ Macrophages and POSTN+ Fibroblasts Contribute to Fibrotic Scarring in Acne Keloidalis

Acne keloidalis is a primary scarring alopecia characterized by longstanding inflammation in the scalp causing keloid-like scar formation and hair loss. Histologically, acne keloidalis is characterized by mixed leukocytic infiltrates in the acute stage followed by a granulomatous reaction and extensive fibrosis in the later stages. To further explore its pathogenesis, bulk RNA sequencing, single-cell RNA sequencing, and spatial transcriptomics were applied to occipital scalp biopsy specimens of lesional and adjacent no-lesional skin in patients with clinically active disease. Unbiased clustering revealed 19 distinct cell populations, including 2 notable populations: POSTN+ fibroblasts with enriched extracellular matrix signatures and SPP1+ myeloid cells with an M2 macrophage phenotype. Cell communication analyses indicated that fibroblasts and myeloid cells communicated by SPP1 signaling networks in lesional skin. A reverse transcriptomics in silico approach identified corticosteroids as possessing the capability to reverse the gene expression signatures of SPP1+ myeloid cells and POSTN+ fibroblasts. Intralesional corticosteroid injection greatly reduced SPP1 and POSTN gene expression as well as acne keloidalis disease activity. Spatial transcriptomics and immunofluorescence staining verified microanatomic specificity of SPP1+ myeloid cells and POSTN+ fibroblasts with disease activity. In summary, the communication between POSTN+ fibroblasts and SPP1+ myeloid cells by SPP1 axis may contribute to the pathogenesis of acne keloidalis.

Transcriptomic evaluation of skin tape-strips in children with allergic asthma uncovers epidermal barrier dysfunction and asthma-associated biomarkers abnormalities

INTRODUCTION

Tape-strips, a minimally invasive method validated for the evaluation of several skin diseases, may help identify asthma-specific biomarkers in the skin of children with allergic asthma.

METHODS

Skin tape-strips were obtained and analyzed with RNA-Seq from children with moderate allergic asthma (MAA) (n = 11, mean age 7.00; SD = 1.67), severe allergic asthma (SAA) (n = 9, mean age 9.11; SD = 2.37), and healthy controls (HCs) (n = 12, mean age 7.36; SD = 2.03). Differentially expressed genes (DEGs) were identified by fold change ≥2 with a false discovery rate <0.05. Transcriptomic biomarkers were analyzed for their accuracy in distinguishing asthma from HCs, their relationships with asthma-related outcomes (exacerbation rate, lung function-FEV1, IOS-R5-20, and lung inflammation-FeNO), and their links to skin (barrier and immune response) and lung (remodeling, metabolism, aging) pathogenetic pathways.

RESULTS

RNA-Seq captured 1113 in MAA and 2117 DEGs in SAA. Epidermal transcriptomic biomarkers for terminal differentiation (FLG/filaggrin), cell adhesion (CDH19, JAM2), lipid biosynthesis/metabolism (ACOT2, LOXL2) were significantly downregulated. Gene set variation analysis revealed enrichment of Th1/IFNγ pathways (p < .01). MAA and SAA shared downregulation of G-protein-coupled receptor (OR4A16, TAS1R3), upregulation of TGF-β/ErbB signaling-related (ACVR1B, EGFR, ID1/2), and upregulation of mitochondrial-related (HIGD2A, VDAC3, NDUFB9) genes. Skin transcriptomic biomarkers correlated with the annualized exacerbation rate and with lung function parameters. A two-gene classifier (TSSC4-FAM212B) was able to differentiate asthma from HCs with 100% accuracy.

CONCLUSION

Tape-strips detected epithelial barrier and asthma-associated signatures in normal-appearing skin from children with allergic asthma and may serve as an alternative to invasive approaches for evaluating asthma endotypes.

Cldn4 overexpression promotes penile cavernous smooth muscle cell fibrotic response via the JNK signaling pathway

BACKGROUND

Erectile dysfunction (ED), defined as the inability to achieve or maintain a penile erection sufficient to satisfy sexual behavior, is prevalent worldwide.

AIM

Using previous research, bioinformatics, and experimental confirmation, we aimed to discover genes that contribute to ED through regulating hypoxia in corpus cavernosum smooth muscle cells (CCSMCs).

METHODS

We used the Gene Expression Omnibus to acquire the sequencing data of the corpus cavernosum transcriptome for diabetic ED and nerve injury type ED rats. We intersected the common differentially expressed genes. Further verification was performed using single cell sequencing. Real-time quantitative polymerase chain reaction and immunofluorescence were used to investigate whether the differentially expressed genes are found in the corpus cavernosum. We used induced hypoxia to assess cell viability changes, and we developed a lentivirus overexpressing Cldn4 for in vitro and in vivo experiments to measure changes in JNK signaling, fibrosis, hypoxia, and erectile function.

OUTCOMES

Our results indicate that targeting the JNK pathway and decreasing local hypoxia may be better options for therapeutic intervention to improve erectile function.

RESULTS

We identified Cldn4 and found its expression increased in the corpora cavernosa of the 2 datasets. In addition, we found that hypoxia can increase the expression of Cldn4, activate the JNK signaling pathway, and exacerbate fibrosis in CCSMCs. Cldn4 overexpression in CCSMCs activated the JNK signaling pathway and increased fibrotic protein expression. Last, rat corpus cavernosum overexpressing Cldn4 activated the JNK signaling pathway, increased local fibrosis, and impaired erectile function.

CLINICAL IMPLICATIONS

Through bioinformatics and in vitro and in vivo experiments, we found that Cldn4 has a negative effect on ED, and targeting Cldn4 may provide new ideas for ED treatment.

STRENGTHS AND LIMITATIONS

Although we have identified Cldn4 as a potential target for ED treatment, we have only conducted preliminary validation on CCMSCs, and we still need to further validate in other cell lines.

CONCLUSION

CCSMC hypoxia leads to increased Cldn4, in both nerve injury and diabetic ED rat models, and promotes fibrosis by activating the JNK signaling pathway.

Wnt5a/β-catenin-mediated epithelial-mesenchymal transition: a key driver of subretinal fibrosis in neovascular age-related macular degeneration

BACKGROUND

Neovascular age-related macular degeneration (nAMD), accounts for up to 90% of AMD-associated vision loss, ultimately resulting in the formation of fibrotic scar in the macular region. The pathogenesis of subretinal fibrosis in nAMD involves the process of epithelial-mesenchymal transition (EMT) occurring in retinal pigment epithelium (RPE). Here, we aim to investigate the underlying mechanisms involved in the Wnt signaling during the EMT of RPE cells and in the pathological process of subretinal fibrosis secondary to nAMD.

METHODS

In vivo, the induction of subretinal fibrosis was performed in male C57BL/6J mice through laser photocoagulation. Either FH535 (a β-catenin inhibitor) or Box5 (a Wnt5a inhibitor) was intravitreally administered on the same day or 14 days following laser induction. The RPE-Bruch's membrane-choriocapillaris complex (RBCC) tissues were collected and subjected to Western blot analysis and immunofluorescence to examine fibrovascular and Wnt-related markers. In vitro, transforming growth factor beta 1 (TGFβ1)-treated ARPE-19 cells were co-incubated with or without FH535, Foxy-5 (a Wnt5a-mimicking peptide), Box5, or Wnt5a shRNA, respectively. The changes in EMT- and Wnt-related signaling molecules, as well as cell functions were assessed using qRT-PCR, nuclear-cytoplasmic fractionation assay, Western blot, immunofluorescence, scratch assay or transwell migration assay. The cell viability of ARPE-19 cells was determined using Cell Counting Kit (CCK)-8.

RESULTS

The in vivo analysis demonstrated Wnt5a/ROR1, but not Wnt3a, was upregulated in the RBCCs of the laser-induced CNV mice compared to the normal control group. Intravitreal injection of FH535 effectively reduced Wnt5a protein expression. Both FH535 and Box5 effectively attenuated subretinal fibrosis and EMT, as well as the activation of β-catenin in laser-induced CNV mice, as evidenced by the significant reduction in areas positive for fibronectin, alpha-smooth muscle actin (α-SMA), collagen I, and active β-catenin labeling. In vitro, Wnt5a/ROR1, active β-catenin, and some other Wnt signaling molecules were upregulated in the TGFβ1-induced EMT cell model using ARPE-19 cells. Co-treatment with FH535, Box5, or Wnt5a shRNA markedly suppressed the activation of Wnt5a, nuclear translocation of active β-catenin, as well as the EMT in TGFβ1-treated ARPE-19 cells. Conversely, treatment with Foxy-5 independently resulted in the activation of abovementioned molecules and subsequent induction of EMT in ARPE-19 cells.

CONCLUSIONS

Our study reveals a reciprocal activation between Wnt5a and β-catenin to mediate EMT as a pivotal driver of subretinal fibrosis in nAMD. This positive feedback loop provides valuable insights into potential therapeutic strategies to treat subretinal fibrosis in nAMD patients.

AMPK signaling inhibits the differentiation of myofibroblasts: impact on age-related tissue fibrosis and degeneration

Disruption of the extracellular matrix (ECM) and an accumulation of fibrotic lesions within tissues are two of the distinctive hallmarks of the aging process. Tissue fibroblasts are mesenchymal cells which display an impressive plasticity in the regulation of ECM integrity and thus on tissue homeostasis. Single-cell transcriptome studies have revealed that tissue fibroblasts exhibit a remarkable heterogeneity with aging and in age-related diseases. Excessive stress and inflammatory insults induce the differentiation of fibroblasts into myofibroblasts which are fusiform contractile cells and abundantly secrete the components of the ECM and proteolytic enzymes as well as many inflammatory mediators. Detrimental stresses can also induce the transdifferentiation of certain mesenchymal and myeloid cells into myofibroblasts. Interestingly, many age-related stresses, such as oxidative and endoplasmic reticulum stresses, ECM stiffness, inflammatory mediators, telomere shortening, and several alarmins from damaged cells are potent inducers of myofibroblast differentiation. Intriguingly, there is convincing evidence that the signaling pathways stimulated by the AMP-activated protein kinase (AMPK) are potent inhibitors of myofibroblast differentiation and accordingly AMPK signaling reduces fibrotic lesions within tissues, e.g., in age-related cardiac and pulmonary fibrosis. AMPK signaling is not only an important regulator of energy metabolism but it is also able to control cell fate determination and many functions of the immune system. It is known that AMPK signaling can delay the aging process via an integrated signaling network. AMPK signaling inhibits myofibroblast differentiation, e.g., by suppressing signaling through the TGF-β, NF-κB, STAT3, and YAP/TAZ pathways. It seems that AMPK signaling can alleviate age-related tissue fibrosis and degeneration by inhibiting the differentiation of myofibroblasts.

Mechanical stiffness promotes skin fibrosis via Piezo1-Wnt2/Wnt11-CCL24 positive feedback loop

Skin fibrosis is characterized by the excessive accumulation of extracellular matrix (ECM) caused by fibrotic disorders of the skin. In recent years, ECM stiffness has emerged as a prominent mechanical cue that precedes skin fibrosis and drives its progression by promoting fibroblasts activation. However, how stiffness influences fibroblasts activation for skin fibrosis progression remains unknown. Here, we report a positive feedback loop mediated by the mechanosensitive ion channel Piezo1 and aberrant tissue mechanics in driving skin fibrosis. Piezo1 is upregulated in fibrotic skin in both humans and mice. Piezo1 knockdown dermal fibroblasts lose their fibroproliferative phenotypes despite being grown on a stiffer substrate. We show that Piezo1 acts through the Wnt2/Wnt11 pathway to mechanically induce secretion of C-C motif chemokine ligand 24 (CCL24, also known as eotaxin-2), a potent cytokine associated with fibrotic disorders. Importantly, adeno-associated virus (AAV)-mediated Piezo1 knockdown ameliorated the progression of skin fibrosis and skin stiffness in mice. Overall, increased matrix stiffness promotes skin fibrosis through the inflammatory Piezo1-Wnt2/Wnt11-CCL24 pathway. In turn, a stiffer skin microenvironment increases Piezo1 expression to exacerbate skin fibrosis aggression. Therefore, targeting Piezo1 represents a strategy to break the positive feedback loop between fibroblasts mechanotransduction and aberrant tissue mechanics in skin fibrosis.

Jianghu decoction and its active component polydatin inhibit inflammation and fibrotic lesions in the lungs of ILD mice via the AMPK signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Recently, interstitial lung disease (ILD) morbidity and mortality have been increasing with insidious epidemiological characteristics. Jianghu decoction (JH) is an effective Chinese medicine for ILD.

AIM OF THE STUDY

We aimed to reveal the material basis and mechanism of action of JH in the treatment of ILD.

MATERIALS AND METHODS

In this study, an ILD mouse model was constructed with bleomycin. HE staining, transcriptome analysis, parallel reaction monitoring-mass spectrometry (PRM-MS), UPLC‒MS, and western blotting assays were conducted.

RESULTS

HE staining results showed that JH effectively reduced inflammation and fibrosis foci in the lungs of the ILD model. Furthermore, transcriptome analysis revealed that JH regulates a set of biological signaling pathways related to immune inflammation and fibrosis. PRM-MS combined with western blotting was applied to detect inflammation and fibrosis involving proteins in lung tissue. JH effectively reversed the aberrant expression of HMGB1, RAGE, SEPTIN4, ACTA2, and ITGAV proteins in the model group. AMPK was identified as the core upstream regulatory protein for JH-mediated ILD regulation. In addition, UHPLC‒MS technology was applied to determine the active ingredients of JH. A total of 80 components were identified from JH, and polydatin (PD) was identified as the active ingredient that effectively alleviated lung fibrosis and inflammatory injury in ILD mice. To illustrate the molecular regulatory network of JH and PD in alleviating lung fibrosis and inflammatory injury, we also examined inflammation and fibrosis-related molecules downstream of the AMPK pathway with RT‒qPCR and western blotting.

CONCLUSIONS

The results showed that both JH and its active component PD exert synergistic inhibition on pulmonary fibrosis and inflammation. Specifically, the AMPK/PGC1α/PPARγ signaling pathway was activated, and the AMPK/HMGB1/RAGE signaling pathway was inhibited in ILD lungs responding to JH or PD administration.

Ex vivo tissue perturbations coupled to single-cell RNA-seq reveal multilineage cell circuit dynamics in human lung fibrogenesis

Pulmonary fibrosis develops as a consequence of failed regeneration after injury. Analyzing mechanisms of regeneration and fibrogenesis directly in human tissue has been hampered by the lack of organotypic models and analytical techniques. In this work, we coupled ex vivo cytokine and drug perturbations of human precision-cut lung slices (hPCLS) with single-cell RNA sequencing and induced a multilineage circuit of fibrogenic cell states in hPCLS. We showed that these cell states were highly similar to the in vivo cell circuit in a multicohort lung cell atlas from patients with pulmonary fibrosis. Using micro-CT-staged patient tissues, we characterized the appearance and interaction of myofibroblasts, an ectopic endothelial cell state, and basaloid epithelial cells in the thickened alveolar septum of early-stage lung fibrosis. Induction of these states in the hPCLS model provided evidence that the basaloid cell state was derived from alveolar type 2 cells, whereas the ectopic endothelial cell state emerged from capillary cell plasticity. Cell-cell communication routes in patients were largely conserved in hPCLS, and antifibrotic drug treatments showed highly cell type-specific effects. Our work provides an experimental framework for perturbational single-cell genomics directly in human lung tissue that enables analysis of tissue homeostasis, regeneration, and pathology. We further demonstrate that hPCLS offer an avenue for scalable, high-resolution drug testing to accelerate antifibrotic drug development and translation.

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.

Asarinin attenuates bleomycin-induced pulmonary fibrosis by activating PPARγ

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

Molecular pathogenesis of subretinal fibrosis in neovascular AMD focusing on epithelial-mesenchymal transformation of retinal pigment epithelium

Age-related macular degeneration (AMD) is a leading cause of vision loss among elderly people in developed countries. Neovascular AMD (nAMD) accounts for more than 90% of AMD-related vision loss. At present, intravitreal injection of anti-vascular endothelial growth factor (anti-VEGF) is widely used as the first-line therapy to decrease the choroidal and retinal neovascularizations, and thus to improve or maintain the visual acuity of the patients with nAMD. However, about 1/3 patients still progress to irreversible visual impairment due to subretinal fibrosis even with adequate anti-VEGF treatment. Extensive literatures support the critical role of epithelial-mesenchymal transformation (EMT) of retinal pigment epithelium (RPE) in the pathogenesis of subretinal fibrosis in nAMD, but the underlying mechanisms still remain largely unknown. This review summarized the molecular pathogenesis of subretinal fibrosis in nAMD, especially focusing on the transforming growth factor-β (TGF-β)-induced EMT pathways. It was also discussed how these pathways crosstalk and respond to signals from the microenvironment to mediate EMT and contribute to the progression of nAMD-related subretinal fibrosis. Targeting EMT signaling pathways might provide a promising and effective therapeutic strategy to treat subretinal fibrosis secondary to nAMD.

Dehydrozingerone alleviates pulmonary fibrosis via inhibition of inflammation and epithelial-mesenchymal transition by regulating the Wnt/β-catenin pathway

In idiopathic pulmonary fibrosis (IPF), excessive collagen deposition predisposes to irreversible lung function decline, respiratory failure, and ultimately death. Due to the limited therapeutic efficacy of FDA-approved medications, novel drugs are warranted for better treatment outcomes. Dehydrozingerone (DHZ) is an analogue of curcumin that has been investigated against pulmonary fibrosis using a bleomycin-induced pulmonary fibrosis model in rats. In in vitro, TGF-β-induced differentiation models (NHLF, LL29, DHLF and A549 cells) were adopted to assess fibrotic markers expression and explored the mechanism of action. DHZ administration attenuated the bleomycin-induced elevation of lung index, inflammatory cell infiltrations, and hydroxyproline levels in lung tissues. Furthermore, treatment with DHZ mitigated the bleomycin-mediated elevation of extracellular matrix (ECM), epithelial-to-mesenchymal-transition (EMT), and collagen deposition markers and improved lung mechanics. In addition, treatment with DHZ significantly suppressed the BLM-induced apoptosis and rescued the BLM-induced pathological abnormalities in lung tissues. In-vitro assays revealed that DHZ suppressed the expression of TGF-β-elevated collagen deposition, EMT and ECM markers in both mRNA/protein levels. Our findings showed that DHZ has anti-fibrotic effect against pulmonary fibrosis by modulating Wnt/β-catenin signaling, suggesting that DHZ may serve as a potential treatment option for IPF.

Theroleofinterleukin-1familyinfibroticdiseases

Fibrosis refers to the phenomenon that fibrous connective tissues are increased and parenchymal cells are decreased in organs or tissues such as lung, heart, liver, kidney, skin and so on. It usually occurs at the late stage of repair of chronic or recurrent tissue damage. Fibrotic disease is the main factor for the morbidity and mortality of all tissues and organ systems. Long-term fibrosis can lead to organ and tissue dysfunction and even failure. Interleukin -1 family cytokines are a series of classical inflammatory factors and involved in the occurrence and development process of multiple fibrotic diseases, its biological function, relationship with diseases and application are more and more favored by scientists from various countries. So far, 11 cytokines and 10 receptors of IL-1 family have been identified. In this paper, the cytokines, receptors, signaling pathways and biological functions of IL-1 family are summarized, and the correlation with fibrosis diseases is analyzed.

The Molecular Mechanisms of Systemic Sclerosis-Associated Lung Fibrosis

Systemic sclerosis (SSc), also known as scleroderma, is an autoimmune disorder that affects the connective tissues and has the highest mortality rate among the rheumatic diseases. One of the hallmarks of SSc is fibrosis, which may develop systemically, affecting the skin and virtually any visceral organ in the body. Fibrosis of the lungs leads to interstitial lung disease (ILD), which is currently the leading cause of death in SSc. The identification of effective treatments to stop or reverse lung fibrosis has been the main challenge in reducing SSc mortality and improving patient outcomes and quality of life. Thus, understanding the molecular mechanisms, altered pathways, and their potential interactions in SSc lung fibrosis is key to developing potential therapies. In this review, we discuss the diverse molecular mechanisms involved in SSc-related lung fibrosis to provide insights into the altered homeostasis state inherent to this fatal disease complication.

LncRNA HOTAIR promotes myocardial fibrosis in atrial fibrillation through binding with PTBP1 to increase the stability of Wnt5a

BACKGROUND

Atrial fibrillation (AF) is one of the most common arrhythmia in clinical practice, and atrial fibrosis is the important mediator in AF. LncRNA HOTAIR was reported to be up-regulated in AF, while the underlying mechanism of HOTAIR in AF remains unclear.

METHODS

In vitro and in vivo AF model was established. qRT-PCR and Western blotting were used to assess the mRNA expression (HOTAIR, Wnt5a and PTBP1) and protein levels (Wnt5a, collagen I/III, α-SMA, CTGF, p-ERK, ERK, p-JNK, and JNK), respectively. MTT, CCK8, transwell assay was used to test cell viability, proliferation and migration, respectively. RIP assay assessed the correlation among HOTAIR, PTBP1 and Wnt5a. The level of α-SMA was detected by immunofluorescence. HE and Masson staining detected the histological changes and fibrosis in mouse heart tissues.

RESULTS

Ang II significantly increased the viability of atrial fibroblasts. The levels of HOTAIR and Wnt5a in fibroblasts were up-regulated by Ang II. HOTAIR silencing or Wnt5a significantly inhibited Ang II-induced proliferation, migration and fibrosis in fibroblasts. HOTAIR silencing repressed Wnt5a-mediated ERK and JNK signaling pathway, and Wnt5a partially abolished the effect of HOTAIR silencing on cell proliferation, migration and fibrosis. Meanwhile, HOTAIR could increase the mRNA stability of Wnt5a via recruiting PTBP1. Furthermore, HOTAIR knockdown notably inhibited the fibrosis in heart tissues of AF mice via regulation of Wnt signaling.

CONCLUSION

HOTAIR could promote atrial fibrosis in AF through binding with PTBP1 to increase Wnt5a stability. Our study might shed new insights on exploring new strategies against AF.

Combined – whole blood and skin fibroblasts- transcriptomic analysis in Psoriatic Arthritis reveals molecular signatures of activity, resistance and early response to treatment

Background

An interplay between immune cells and resident skin and joint stromal cells is implicated in psoriatic arthritis (PsA), yet the mechanisms remain elusive with a paucity of molecular biomarkers for activity and response. Combined transcriptomic and immunophenotypic analysis of whole blood and skin fibroblasts could provide further insights.

Methods

Whole blood RNA-seq was performed longitudinally in 30 subjects with PsA at the beginning, one and six months after treatment, with response defined at six months. As control groups, 10 healthy individuals and 10 subjects with rheumatoid arthritis (RA) were recruited combined with public datasets from patients with psoriasis (PsO) and systemic lupus erythematous (SLE). Differential expression analysis and weighted gene co-expression network analysis were performed to identify gene expression signatures, while deconvolution and flow cytometry to characterize the peripheral blood immune cell profile. In a subset of affected and healthy individuals, RNA-seq of skin fibroblasts was performed and subjected to CellChat analysis to identify the blood-skin fibroblast interaction network.

Results

PsA demonstrated a distinct “activity” gene signature in the peripheral blood dominated by TNF- and IFN-driven inflammation, deregulated cholesterol and fatty acid metabolism and expansion of pro-inflammatory non-classical monocytes. Comparison with the blood transcriptome of RA, PsO, and SLE revealed a “PsA-specific signature” enriched in extracellular matrix remodeling. This was further supported by the skin fibroblast gene expression profile, displaying an activated, proliferating phenotype, and by skin-blood interactome analysis revealing interactions with circulating immune cells through WNT, PDGF and immune-related semaphorins. Of note, resistance to treatment was associated with upregulation of genes involved in TGFβ signaling and angiogenesis and persistent increase of non-classical monocytes. Differentially expressed genes related to platelet activation and hippo signaling discriminated responders and non-responders as early as one month after treatment initiation.

Conclusion

Transcriptome analysis of peripheral blood and skin fibroblasts in PsA reveals a distinct disease activity signature and supports the involvement of skin fibroblasts through their activation and interaction with circulating immune cells. Aberrant TGFβ signaling and persistently increased non-classical monocytes characterize treatment-resistant PsA, with pro-inflammatory pathways related to platelet activation and Hippo signaling predicting early response to treatment.

Number 2 Feibi Recipe Ameliorates Pulmonary Fibrosis by Inducing Autophagy Through the GSK-3β/mTOR Pathway

Number 2 Feibi Recipe (N2FBR) is a traditional Chinese medicine formula for treating idiopathic pulmonary fibrosis. N2FBR inhibits H₂O₂-mediated oxidative stress damage in alveolar epithelial cells by increasing autophagy, as we previously demonstrated. However, it is unknown if similar mechanisms occur in vivo. We established a pulmonary fibrosis model by instilling bleomycin (BLM) from the airway to examine the effects of N2FBR on pulmonary fibrosis and investigate its probable mechanism in this work. We discovered that N2FBR treatment effectively alleviated interstitial fibrosis as well as collagen deposition, primarily in upregulating SOD, GSH-Px, T-AOC and downregulating MDA content. N2FBR also increased the expression of LC3B, Beclin-1, LAMP1, TFEB and downregulated the expression of p62, legumain. N2FBR treatment boosted the production of autophagosomes, according to the results of the TEM observation. Furthermore, we explored that N2FBR exerted its anti-oxidative stress and pro-autophagy effects via GSK-3β/mTOR signalling pathway. Therefore, these results provide further evidence for the protective effect of N2FBR in pulmonary fibrosis. Our findings could have ramifications for the development of antifibrosis therapies.

TRAF6 Suppresses the Development of Pulmonary Fibrosis by Attenuating the Activation of Fibroblasts

Pulmonary fibrosis (PF) has a high mortality rate, and its pathogenesis is unknown. TNF receptor-associated factor 6 (TRAF6), a signal transducer for inflammatory signaling, plays crucial roles in the pathogenesis of immune diseases. However, its function in PF remains unknown. Herein, we demonstrated that lungs from mice with bleomycin (BLM)-induced PF were characterized by decreased expression of TRAF6 in lung fibroblasts. Enhancing TRAF6 expression protected mice from BLM-induced PF coupled with a significant reduction in fibroblast differentiation. Furthermore, we demonstrated that overexpression of TRAF6 reversed the activation of myofibroblasts from PF mice by reducing the expression of Wnt3a and subsequently suppressing Wnt/β-catenin signaling. Additionally, the abundance of Tribbles pseudokinase 3 (TRIB3), a stress sensor, was negatively correlated with the abundance of TRAF6 in lung fibroblasts. TRIB3 overexpression decreased TRAF6 abundance by reducing TRAF6 stability in lung fibroblasts during PF. Mechanistic studies revealed that TRIB3 bound to TRAF6 and accelerated basal TRAF6 ubiquitination and degradation. Collectively, our data indicate that reduced TRAF6 expression in fibroblasts is essential for the progression of PF, and therefore, genetically increasing TRAF6 expression or disrupting the TRIB3-TRAF6 interaction could be potential therapeutic strategies for fibroproliferative lung diseases in clinical settings.