microRNA-30a attenuates TGF-β1-induced activation of pulmonary fibroblast cell by targeting FAP-α

Fibroblast activation protein-sensitive polymeric nanobeacon for early diagnosis of renal fibrosis

Early diagnosis and treatment of renal fibrosis (RF) significantly affect the clinical outcomes of chronic kidney diseases (CKDs). As the typical fibrotic ailment, RF is characterized by remodeling of the extracellular matrix, and the activation of fibroblast activation protein (FAP) plays a crucial role in the mediation of extracellular matrix protein degradation. Therefore, FAP can serve as a biomarker for RF. However, up to now, no effective tools have been reported to diagnose early-stage RF via detecting FAP. In this work, a polymeric nanobeacon integrating an FAP-sensitive amphiphilic polymer and fluorophores was proposed, which was used to diagnose early RF by sensing FAP. The FAP can be detected in the range of 0 to 200 ng/mL with a detection limit of 0.132 ng/mL. Furthermore, the fluorescence imaging results demonstrate that the polymeric nanobeacon can sensitively image fibrotic kidneys in mice with unilateral ureteral occlusion (UUO), suggesting its potential for early RF diagnosis and guidance of FAP-targeted treatments. Importantly, when employed alongside with non-invasive diagnostic techniques like magnetic resonance imaging (MRI) and serological tests, this nanobeacon exhibits excellent biocompatibility, low biological toxicity, and sustained imaging capabilities, making it a suitable fluorescent tool for diagnosing various FAP-related fibrotic conditions. To our knowledge, this study represents the first attempt to image RF in early stage by detecting FAP, offering a promising fluorescent molecular tool for diagnosing various FAP-associated diseases in the future.

Network-based drug repositioning of linagliptin as a potential agent for uterine fibroids targeting transforming growth factor-beta mediated fibrosis

Uterine fibroid is the most common non-cancerous tumor with no satisfactory options for long-term pharmacological treatment. Fibroblast activation protein-α (FAP) is one of the critical enzymes that enhances the fibrosis in uterine fibroids. Through STITCH database mining, we found that dipeptidyl peptidase-4 inhibitors (DPP4i) have the potential to inhibit the activity of FAP. Both DPP4 and FAP belong to the dipeptidyl peptidase family and share a similar catalytic domain. Hence, ligands which have a binding affinity with DPP4 could also bind with FAP. Among the DPP4i, linagliptin exhibited the highest binding affinity (Dock score = -8.562 kcal/mol) with FAP. Our study uncovered that the differences in the S2 extensive-subsite residues between DPP4 and FAP could serve as a basis for designing selective inhibitors specifically targeting FAP. Furthermore, in a dynamic environment, linagliptin was able to destabilize the dimerization interface of FAP, resulting in potential inhibition of its biological activity. True to the in-silico results, linagliptin reduced the fibrotic process in estrogen and progesterone-induced fibrosis in rat uterus. Furthermore, linagliptin reduced the gene expression of transforming growth factor-β (TGF-β), a critical factor in collagen secretion and fibrotic process. Masson trichrome staining confirmed that the anti-fibrotic effects of linagliptin were due to its ability to reduce collagen deposition in rat uterus. Altogether, our research proposes that linagliptin has the potential to be repurposed for the treatment of uterine fibroids.

circNOX4 activates an inflammatory fibroblast niche to promote tumor growth and metastasis in NSCLC via FAP/IL-6 axis

BACKGROUND

Cancer-associated fibroblasts (CAFs) orchestrate a supportive niche that fuels cancer metastatic development in non-small cell lung cancer (NSCLC). Due to the heterogeneity and plasticity of CAFs, manipulating the activated phenotype of fibroblasts is a promising strategy for cancer therapy. However, the underlying mechanisms of fibroblast activation and phenotype switching that drive metastasis remain elusive.

METHODS

The clinical implications of fibroblast activation protein (FAP)-positive CAFs (FAP+CAFs) were evaluated based on tumor specimens from NSCLC patients and bioinformatic analysis of online databases. CAF-specific circular RNAs (circRNAs) were screened by circRNA microarrays of primary human CAFs and matched normal fibroblasts (NFs). Survival analyses were performed to assess the prognostic value of circNOX4 in NSCLC clinical samples. The biological effects of circNOX4 were investigated by gain- and loss-of-function experiments in vitro and in vivo. Fluorescence in situ hybridization, luciferase reporter assays, RNA immunoprecipitation, and miRNA rescue experiments were conducted to elucidate the underlying mechanisms of fibroblast activation. Cytokine antibody array, transwell coculture system, and enzyme-linked immunosorbent assay (ELISA) were performed to investigate the downstream effectors that promote cancer metastasis.

RESULTS

FAP+CAFs were significantly enriched in metastatic cancer samples, and their higher abundance was correlated with the worse overall survival in NSCLC patients. A novel CAF-specific circRNA, circNOX4 (hsa_circ_0023988), evoked the phenotypic transition from NFs into CAFs and promoted the migration and invasion of NSCLC in vitro and in vivo. Clinically, circNOX4 correlated with the poor prognosis of advanced NSCLC patients. Mechanistically, circNOX4 upregulated FAP by sponging miR-329-5p, which led to fibroblast activation. Furthermore, the circNOX4/miR-329-5p/FAP axis activated an inflammatory fibroblast niche by preferentially inducing interleukin-6 (IL-6) and eventually promoting NSCLC progression. Disruption of the intercellular circNOX4/IL-6 axis significantly suppressed tumor growth and metastatic colonization in vivo.

CONCLUSIONS

Our study reveals a role of the circRNA-induced fibroblast niche in tumor metastasis and highlights that targeting the circNOX4/FAP/IL-6 axis is a promising strategy for the intervention of NSCLC metastasis.

Fibroblast Activation Protein Alpha (FAPα) in Fibrosis: Beyond a Perspective Marker for Activated Stromal Cells?

The development of tissue fibrosis is a complex process involving the interaction of multiple cell types, which makes the search for antifibrotic agents rather challenging. So far, myofibroblasts have been considered the key cell type that mediated the development of fibrosis and thus was the main target for therapy. However, current strategies aimed at inhibiting myofibroblast function or eliminating them fail to demonstrate sufficient effectiveness in clinical practice. Therefore, today, there is an unmet need to search for more reliable cellular targets to contribute to fibrosis resolution or the inhibition of its progression. Activated stromal cells, capable of active proliferation and invasive growth into healthy tissue, appear to be such a target population due to their more accessible localization in the tissue and their high susceptibility to various regulatory signals. This subpopulation is marked by fibroblast activation protein alpha (FAPα). For a long time, FAPα was considered exclusively a marker of cancer-associated fibroblasts. However, accumulating data are emerging on the diverse functions of FAPα, which suggests that this protein is not only a marker but also plays an important role in fibrosis development and progression. This review aims to summarize the current data on the expression, regulation, and function of FAPα regarding fibrosis development and identify promising advances in the area.

MicroRNA-30a depresses hepatic stellate cell activation against liver fibrosis through blockade of the TGF-β1/Smad2/3 pathway

This study explored the mechanism of microRNA (miR)-30a in the activation of hepatic stellate cells (HSCs) to deepen the understanding of the pathogenesis of liver fibrosis. Subsequent to knockdown and ectopic experiments, HSCs were induced with 10 ng/mL transforming growth factor (TGF)-β1 to inspect the role of the miR-30a/TGF-β receptor 1 (TGFBR1) axis in HSC proliferation and activation. qRT-PCR was utilized to examine TGFBR1 mRNA and miR-30a expression and western blot to test TGFBR1, alpha smooth muscle actin (α-SMA), Collagen I and mothers against DPP homolog 2/3 (Smad2/3) protein expression. The fluorescence intensity of α-SMA was measured with immunofluorescence staining. The interaction of TGFBR1 with miR-30a was tested with a dual-luciferase reporter assay. TGF-β1 treated HSCs had upregulated expressions of α-SMA and Collagen I. In addition, downregulated miR-30a, upregulated TGFBR1 and activated TGF-β1/Smad2/3 pathway were found in activated HSCs. Upregulation of miR-30a or downregulation of TGFBR1 suppressed the activation and growth of HSCs. miR-30a repression activated the TGF-β1/Smad2/3 pathway and promoted HSC proliferation and activation, while suppression of TGFBR1 revered these effects. miR-30a was an upstream regulatory factor of TGFBR1. miR-30a blocks the TGF-β1/Smad2/3 pathway to inhibit HSC activation against liver fibrosis by targeting TGFBR1.

Role and mechanism of fibroblast-activated protein-α expression on the surface of fibroblast-like synoviocytes in rheumatoid arthritis

Fibroblast-activated protein-α (FAP) is a type II integrated serine protease expressed by activated fibroblasts during fibrosis or inflammation. Fibroblast-like synoviocytes (FLSs) in rheumatoid arthritis (RA) synovial sites abundantly and stably overexpress FAP and play important roles in regulating the cellular immune, inflammatory, invasion, migration, proliferation, and angiogenesis responses in the synovial region. Overexpression of FAP is regulated by the initial inflammatory microenvironment of the disease and epigenetic signaling, which promotes RA development by regulating FLSs or affecting the signaling cross-linking FLSs with other cells at the local synovium and inflammatory stimulation. At present, several treatment options targeting FAP are in the process of development. This review discusses the basic features of FAP expressed on the surface of FLSs and its role in RA pathophysiology and advances in targeted therapies.

The role of interleukin 36γ in the epithelial-mesenchymal transition process of chronic rhinosinusitis: A pilot study

PURPOSE

Epithelial-mesenchymal transition (EMT) is an important characteristic in the remodelling of chronic rhinosinusitis with nasal polyps (CRSwNP). IL-36γ and fibroblast activation protein (FAP) may exacerbate remodelling in CRS. Here, we aimed to determine whether IL-36γ and FAP expression are associated with EMT and may be a predictor for CRSwNP prognosis.

METHODS

Fifty-two non-Eos CRSwNP patients and 12 control patients were obtained and were followed up for more than 1 year after surgery. IL-36γ, FAP and EMT markers expression were evaluated by real-time polymerase chain reaction and western blot. Masson trichrome staining was adopted to assess tissue fibrotic changes. Furthermore, the soluble form of IL-36γ and FAP in nasal secretions was detected by ELISA.

RESULTS

While basal expression of E-cadherin decreased, the expression of IL-36γ, vimentin and FAP increased in nasal polyps. In well-prognosis patients, the expression of IL-36γ, vimentin and FAP were significantly decreased than in poor-prognosis patients, while the protein expression of E-cadherin was increased. The protein expression of IL-36γ was notably increased in recurrent nasal polyps than in preoperation specimens. A positive relationship between IL-36γ and FAP expression, a negative relationship between IL-36γ and E-cad expression was noted. The soluble form of IL-36γ and FAP increased during the development of non-Eos CRSwNP, with the highest level in poor-prognosis patients after surgery.

CONCLUSION

Non-Eos CRSwNP have partially undergone EMT under baseline conditions. IL-36γ and FAP expression were related with EMT, the soluble form of IL-36γ and FAP in nasal secretions may predict the prognosis of patients.

Comprehensive Analysis of Fibroblast Activation Protein Expression in Interstitial Lung Diseases

Rationale: Sustained activation of lung fibroblasts and the resulting oversynthesis of the extracellular matrix are detrimental events for patients with interstitial lung diseases (ILDs). Lung biopsy is a primary evaluation technique for the fibrotic status of ILDs, and is also a major risk factor for triggering acute deterioration. Fibroblast activation protein (FAP) is a long-known surface biomarker of activated fibroblasts, but its expression pattern and diagnostic implications in ILDs are poorly defined. Objectives: The present study aims to comprehensively investigate whether the expression intensity of FAP could be used as a potential readout to estimate or measure the amounts of activated fibroblasts in ILD lungs quantitatively. Methods: FAP expression in human primary lung fibroblasts as well as in clinical lung specimens was first tested using multiple experimental methods, including real-time quantitative PCR (qPCR), Western blot, immunofluorescence staining, deep learning measurement of whole slide immunohistochemistry, as well as single-cell sequencing. In addition, FAP-targeted positron emission tomography/computed tomography imaging PET/CT was applied to various types of patients with ILD, and the correlation between the uptake of FAP tracer and pulmonary function parameters was analyzed. Measurements and Main Results: Here, it was revealed, for the first time, FAP expression was upregulated significantly in the early phase of lung fibroblast activation event in response to a low dose of profibrotic cytokine. Single-cell sequencing data further indicate that nearly all FAP-positive cells in ILD lungs were collagen-producing fibroblasts. Immunohistochemical analysis validated that FAP expression level was closely correlated with the abundance of fibroblastic foci on human lung biopsy sections from patients with ILDs. We found that the total standard uptake value (SUV) of FAP inhibitor (FAPI) PET (SUVtotal) was significantly related to lung function decline in patients with ILD. Conclusions: Our results strongly support that in vitro and in vivo detection of FAP can assess the profibrotic activity of ILDs, which may aid in early diagnosis and the selection of an appropriate therapeutic window.

Mesoporous Polydopamine Loaded Pirfenidone Target to Fibroblast Activation Protein for Pulmonary Fibrosis Therapy

Recently, fibroblast activation protein (FAP), an overexpressed transmembrane protein of activated fibroblast in pulmonary fibrosis, has been considered as the new target for diagnosing and treating pulmonary fibrosis. In this work, mesoporous polydopamine (MPDA), which is facile prepared and easily modified, is developed as a carrier to load antifibrosis drug pirfenidone (PFD) and linking FAP inhibitor (FAPI) to realize lesion-targeted drug delivery for pulmonary fibrosis therapy. We have found that PFD@MPDA-FAPI is well biocompatible and with good properties of antifibrosis, when ICG labels MPDA-FAPI, the accumulation of the nanodrug at the fibrosis lung in vivo can be observed by NIR imaging, and the antifibrosis properties of PFD@MPDA-FAPI in vivo were also better than those of pure PFD and PFD@MPDA; therefore, the easily produced and biocompatible nanodrug PFD@MPDA-FAPI developed in this study is promising for further clinical translations in pulmonary fibrosis antifibrosis therapy.

Role of MicroRNAs in Signaling Pathways Associated with the Pathogenesis of Idiopathic Pulmonary Fibrosis: A Focus on Epithelial-Mesenchymal Transition

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive disease with high mortality and unclear etiology. Previous evidence supports that the origin of this disease is associated with epigenetic alterations, age, and environmental factors. IPF initiates with chronic epithelial lung injuries, followed by basal membrane destruction, which promotes the activation of myofibroblasts and excessive synthesis of extracellular matrix (ECM) proteins, as well as epithelial-mesenchymal transition (EMT). Due to miRNAs’ role as regulators of apoptosis, proliferation, differentiation, and cell-cell interaction processes, some studies have involved miRNAs in the biogenesis and progression of IPF. In this context, the analysis and discussion of the probable association of miRNAs with the signaling pathways involved in the development of IPF would improve our knowledge of the associated molecular mechanisms, thereby facilitating its evaluation as a therapeutic target for this severe lung disease. In this work, the most recent publications evaluating the role of miRNAs as regulators or activators of signal pathways associated with the pathogenesis of IPF were analyzed. The search in Pubmed was made using the following terms: “miRNAs and idiopathic pulmonary fibrosis (IPF)”; “miRNAs and IPF and signaling pathways (SP)”; and “miRNAs and IPF and SP and IPF pathogenesis”. Additionally, we focus mainly on those works where the signaling pathways involved with EMT, fibroblast differentiation, and synthesis of ECM components were assessed. Finally, the importance and significance of miRNAs as potential therapeutic or diagnostic tools for the treatment of IPF are discussed.

Fibroblast activation protein-alpha knockdown suppresses prostate cancer cell invasion and proliferation

BACKGROUND

Prostate cancer is one of the most common malignant tumors of the male genitourinary system. Fibroblast activation protein alpha (FAP-α) overexpression has been shown to occur in a wide range of tumors. However, the specific mechanism of FAP-α in the development of prostate cancer has not been reported.

METHODS

In this study, real-time quantitative PCR (qRT-PCR) was used to detect the relative expression of FAP-α mRNA in prostate cancer cell lines (PC-3, LNCaP, and DU145) and human normal prostate epithelial cell line RWPE-1. Small interfering RNA (siRNA) targeting FAP-α and vectors expressing exogenous FAP-α were transfected to prostate cancer cells (LNCaP and DU145) to investigate the function of FAP-α. BALB/c nude mice were injected with DU145 cells which were transfected with NC-siRNA, FAP-α-siRNA-1, or FAP-α-siRNA-2.

RESULTS

Compared to adjacent normal tissues, FAP-α protein and mRNA levels in prostate cancer tissues increased significantly (P<0.05). Compared to patients with high FAP-α mRNA levels, patients with low FAP-α mRNA levels had a significantly higher survival rate (χ²=5.050, log-rank P=0.025). Overexpression of FAP-α in LNCaP cells markedly inhibited cell apoptosis, and promoted cell invasion and proliferation. In contrast, knockdown of FAP-α expression in DU145 cells can significantly reduce invasion, proliferation, and promote apoptosis in prostate cancer. Immunofluorescence assay further indicated that down-regulation of FAP-α could suppress the nuclear translocation of β-catenin. An in vivo study found that compared with the NC-siRNA group, the tumor weight and tumor volume in the FAP-α-siRNA-1 and FAP-α-siRNA-2 groups were significantly decreased.

CONCLUSIONS

In conclusion, down-regulation of FAP-α can inhibit the invasion and proliferation of prostate cancer. Our study provides a theoretical basis for the targeted treatment of prostate cancer.

Pterostilbene alleviates pulmonary fibrosis by regulating ASIC2

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

LncRNA SOX2OT/Smad3 feedback loop promotes myocardial fibrosis in heart failure

Long noncoding RNA SOX2OT is associated with myocardial fibrosis (MF) in heart failure (HF). This article aims to investigate the role of SOX2OT in MF. We constructed HF mouse models by subcutaneous injection of isoprenaline (ISO). Cardiac fibroblasts (CFs) were treated with ISO to induce MF.Hematoxylin-eosin, Masson, and Sirius-red staining were used to identify myocardial injury and collagen deposition in heart tissues. The relationship among SOX2OT, miR-138-5p, TGF-β1, and Smad3 were evaluated by chromatin immunoprecipitation and luciferase reporter assay. The gene and protein expression were verified by quantitative real-time PCR and western blot. We found that SOX2OT was up-regulated in HF mice and ISO-induced CFs. SOX2OT knockdown reduced myocardial injury and collagen deposition in HF mice. The expression of collagen I, α-SMA, TGF-β1, and p-Smad3 were inhibited by SOX2OT down-regulation in HF mice and ISO-induced CFs. Furthermore, TGF-β1 was a target gene of miR-138-5p and indirectly regulated by SOX2OT. SOX2OT promoted MF in HF by activating TGF-β1/Smad3, and then Smad3 interacted with the SOX2OT promoter and formed a positive feedback loop. In conclusion, our work verifies that SOX2OT/Smad3 feedback loop promotes MF in HF. Thus, SOX2OT is potentially a novel therapeutic target for MF in HF.

microRNA-30a attenuates TGF-β1-induced activation of pulmonary fibroblast cell by targeting FAP-α

Idiopathic interstitial pulmonary fibrosis is a common diffuse interstitial lung disease and has poor prognosis. And one of the pathological features of it is persistent fibroblast activation. It was reported that microRNA‐30a was down‐regulated in bronchoalveolar lavage fluid from idiopathic pulmonary fibrosis patients. But whether miR‐30a is involved in fibroblast activation and its specific mechanism is unclear. In this study, we aimed to investigate the role of miR‐30a in fibroblast activation induced by TGF‐β1. We found miR‐30a could targetedly suppress FAP‐α expression. In MRC5 cells, miR‐30a was not only involved in regulating the expression of FAP‐α, col1a and α‐SMA induced by TGF‐β1 but also had a role in cell proliferation with or without TGF‐β1 treatment via regulating FAP‐α expression. Thus, the results indicated that miR‐30a alleviated fibroblast activation by regulating the expression of FAP‐α.