STAT3 controls COL1A2 enhancer activation cooperatively with JunB, regulates type I collagen synthesis posttranscriptionally, and is essential for lung myofibroblast differentiation

M2 macrophage infusion ameliorates diabetic glomerulopathy via the JAK2/STAT3 pathway in db/db mice

Objectives: To explore the therapeutic effects of M2 macrophages in diabetic nephropathy (DN) and their mechanism.Methods: We infused M2 macrophages stimulated with IL-4 into 10-week-old db/db mice once a week for 4 weeks through the tail vein as M2 group. Then we investigated the role of M2 macrophages in alleviating the infammation of DN and explored the mechanism.Results: M2 macrophages hindered the progression of DN, reduced the levels of IL-1β (DN group was 34%, M2 group was 13%, p < 0.01) and MCP-1 (DN group was 49%, M2 group was 16%, p < 0.01) in the glomeruli. It was also proven that M2 macrophages alleviate mesangial cell injury caused by a high glucose environment. M2 macrophage tracking showed that the infused M2 macrophages migrated to the kidney, and the number of M2 macrophages in the kidney reached a maximum on day 3. Moreover, the ratio of M2 to M1 macrophages was 2.3 in the M2 infusion group, while 0.4 in the DN group (p < 0.01). Mechanistically, M2 macrophages downregulated Janus kinase (JAK) 2 and signal transducer and activator of transcription (STAT) 3 in mesangial cells.Conclusions: Multiple infusions of M2 macrophages significantly alleviated inflammation in the kidney and hindered the progression of DN at least partially by abrogating the M1/M2 homeostasis disturbances and suppressing the JAK2/STAT3 pathway in glomerular mesangial cells. M2 macrophage infusion may be a new therapeutic strategy for DN treatment.

Combining proteomics and Phosphoproteomics to investigate radiation-induced rectal fibrosis in rats and the effects of pSTAT3 inhibitor S3I-201 on human intestinal fibroblasts

OBJECTIVE

To investigate the regulatory mechanisms of radiation-induced rectal fibrosis (RIRF) and assess the therapeutic potential of S3I-201.

METHODS

Sprague-Dawley rats were divided into control and radiation groups, with the latter exposed to 20 Gray pelvic X-rays. After 10 weeks, rectal tissues were analyzed using tandem mass tag (TMT) proteomics and phosphoproteomics. Pathway enrichment was performed via Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, with secondary annotation using Cluego. Representative proteins and their phosphorylated counterparts were validated through immunoblotting in another cohort. STAT3 levels in rectal tissues from irradiated and non-irradiated colorectal cancer patients were examined, and the effects of S3I-201 on human rectal fibroblasts were evaluated.

RESULTS

The radiation group showed significant inflammatory responses and collagen deposition in the rat rectal walls. Enrichment analysis revealed that radiation-induced proteins and phosphoproteins were primarily involved in extracellular matrix-receptor interaction and the MAPK signaling pathway. Immunoblotting indicated increased expression of p-CAMKII, p-MRACKS, p-Cfl1, p-Myl9, and p-STAT3 in the radiation group compared to the control, while p-AKT1 expression decreased. Elevated phosphorylation of STAT3 was observed in submucosal fibroblasts of the post-radiation human rectum. S3I-201 specifically inhibited STAT3 phosphorylation and suppressed activation of human rectal fibroblasts, also inhibiting the pro-fibrotic effects of the classical TGF-β/Smad/CTGF pathway.

CONCLUSION

By integrating phosphoproteomics and proteomics, this study elucidated the protein regulatory network of RIRF and identified the potential therapeutic targets, including phosphoproteins such as STAT3 in managing RIRF.

SIGNIFICANCE

In our research, we employed TMT labeling alongside LC-MS/MS techniques to comprehensively explore the proteomic and phosphoproteomic landscapes in rat models of radiation-induced intestinal fibrosis (RIRF). Our analysis revealed the function and pathways of proteins and phosphorylated proteins triggered by radiation, as well as those with protective roles. We mapped a network of interactions among these proteins and validated key protein expression levels using quantitative methods. Furthermore, we investigated STAT3 as a potential therapeutic target, assessing the efficacy of the inhibitor S3I-201 in laboratory settings, and highlighting its potential for RIRF treatment. Overall, our findings provide groundbreaking insights into the mechanisms underlying RIRF, paving the way for the development of future antifibrotic therapies.

Hepatic organoids move from adolescence to maturity

Since organoids were developed 15 years ago, they are now in their adolescence as a research tool. The ability to generate 'tissue in a dish' has created enormous opportunities for biomedical research. We examine the contributions that hepatic organoids have made to three areas of liver research: as a source of cells and tissue for basic research, for drug discovery and drug safety testing, and for understanding disease pathobiology. We discuss the features that enable hepatic organoids to provide useful models for human liver diseases and identify four types of advances that will enable them to become a mature (i.e., adult) research tool over the next 5 years. During this period, advances in single-cell RNA sequencing and CRISPR technologies coupled with improved hepatic organoid methodology, which enables them to have a wider range of cell types that are present in liver and to be grown in microwells, will generate discoveries that will dramatically advance our understanding of liver development and the pathogenesis of liver diseases. It will generate also new approaches for treating liver fibrosis, which remains a major public health problem with few treatment options.

Immunosuppressive tumor microenvironment and uterine fibroids: Role in collagen synthesis

Uterine fibroids (UF), also called uterine leiomyoma, is one of the most prevalent uterine tumors. UF represents a serious women's health global problem with a significant physical, emotional, and socioeconomic impact. Risk factors for UF include racial disparities, age, race, hormonal factors, obesity, and lifestyle (diet, physical activity, and stress. There are several biological contributors to UF pathogenesis such as cellular proliferation, angiogenesis, and extracellular matrix (ECM) accumulation. This review addresses tumor immune microenvironment as a novel mediator of ECM deposition. Polarization of immune microenvironment towards the immunosuppressive phenotype has been associated with ECM deposition. Immunosuppressive cells include M2 macrophage, myeloid-derived suppressor cells (MDSCs), and Th17 cells, and their secretomes include interleukin 4 (IL-4), IL-10, IL-13, IL-17, IL-22, arginase 1, and transforming growth factor-beta (TGF-β1). The change in the immune microenvironment not only increase tumor growth but also aids in collagen synthesis and ECM disposition, which is one of the main hallmarks of UF pathogenesis. This review invites further investigations on the change in the UF immune microenvironment as well as a novel targeting approach instead of the traditional UF hormonal and supportive treatment.

JunB: a paradigm for Jun family in immune response and cancer

Jun B proto-oncogene (JunB) is a crucial member of dimeric activator protein-1 (AP-1) complex, which plays a significant role in various physiological processes, such as placental formation, cardiovascular development, myelopoiesis, angiogenesis, endochondral ossification and epidermis tissue homeostasis. Additionally, it has been reported that JunB has great regulatory functions in innate and adaptive immune responses by regulating the differentiation and cytokine secretion of immune cells including T cells, dendritic cells and macrophages, while also facilitating the effector of neutrophils and natural killer cells. Furthermore, a growing body of studies have shown that JunB is involved in tumorigenesis through regulating cell proliferation, differentiation, senescence and metastasis, particularly affecting the tumor microenvironment through transcriptional promotion or suppression of oncogenes in tumor cells or immune cells. This review summarizes the physiological function of JunB, its immune regulatory function, and its contribution to tumorigenesis, especially focusing on its regulatory mechanisms within tumor-associated immune processes.

The rat Achilles and patellar tendons have similar increases in mechanical properties but become transcriptionally divergent during postnatal development

The molecular events that drive post-natal tendon development are poorly characterized. In this study, we profiled morphological, mechanical, and transcriptional changes in the rat Achilles and patellar tendon before walking (P7), shortly after onset of walking (P14), and at motor maturity (P28). The Achilles and patellar tendons increased collagen content and mechanical strength similarly throughout post-natal development. However, at P28 the patellar tendon tended to display a higher maximal tensile load (MTL) (P = 0.0524) than the Achilles tendon, but a similar ultimate tensile strength (UTS; load relative to cross-sectional area) probably due to its increased cross-sectional area during development. The tendons started transcriptionally similar, with overlapping PCA clusters at P7 and P14, before becoming transcriptionally distinct at P28. In both tendons, there was an increase in extracellular matrix (ECM) gene expression and a concomitant decrease in cell cycle and mitochondrial gene expression. The transcriptional divergence at P28 suggested that STAT signalling was lower in the patellar tendon where MTL increased the most. Treating engineered human ligaments with the STAT inhibitor itacitinib increased collagen content and MTL. Our results suggest that during post-natal development, cellular resources are initially allocated towards cell proliferation before shifting towards extracellular matrix development following the onset of mechanical load and provide potential targets for improving tendon function. KEY POINTS: Little is known about mechanisms of post-natal tendon growth. We characterized morphological, mechanical, and transcriptional changes that occur before (P7), and early (P14) and late after (P28) rats begin to walk. From P7 to P28, the Achilles tendon increased in length, whereas the patellar tendon increased in cross-sectional area. Mechanical and material properties of the Achilles and patellar tendon increased from P7 to P28. From P7 to P28, the Achilles and patellar tendons increased expression of ECM genes and decreased mitochondrial and cell cycle gene expression. Ribosomal gene expression also significantly decreased in the Achilles and tended to decrease in the patellar tendon. At P28, STAT1 signalling tended to be lower in the patellar tendon which had grown by increasing cross-sectional area and inhibiting STAT activation in vitro improved mechanical properties in engineered human ligaments.

Hesperidin inhibits lung fibroblast senescence via IL-6/STAT3 signaling pathway to suppress pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and fatal lung disease with obscure pathogenesis. Increasing evidence suggests that cellular senescence is an important mechanism underlying in IPF. Clinical treatment with drugs, such as pirfenidone and nintedanib, reduces the risk of acute exacerbation and delays the decline of pulmonary function in patients with mild to moderate pulmonary fibrosis, and with adverse reactions. Hesperidin was previously shown to alleviate pulmonary fibrosis in rats by attenuating the inflammation response. Our previous research indicated that the Citrus alkaline extracts, hesperidin as the main active ingredient, could exert anti-pulmonary fibrosis effects by inhibiting the senescence of lung fibroblasts. However, whether hesperidin could ameliorate pulmonary fibrosis by inhibiting fibroblast senescence needed further study.

PURPOSE

This work aimed to investigate whether and how hesperidin can inhibit lung fibroblast senescence and thereby alleviate pulmonary fibrosis METHODS: Bleomycin was used to establish a mouse model of pulmonary fibrosis and doxorubicin was used to establish a model of cellular senescence in MRC-5 cells in vitro. The therapeutic effects of hesperidin on pulmonary fibrosis using haematoxylin-eosin staining, Masson staining, enzyme-linked immunosorbent assay, immunohistochemistry, western blotting and quantitative Real-Time PCR. The anti-senescent effect of hesperidin in vivo and in vitro was assessed by western blotting, quantitative Real-Time PCR and senescence-associated β-galactosidase RESULTS: We demonstrated that hesperidin could alleviate bleomycin-induced pulmonary fibrosis in mice. The expression level of senescence marker proteins p53, p21, and p16 was were downregulated, along with the myofibroblast marker α-SMA. The number of senescence-associated β-galactosidase-positive cells was significantly reduced by hesperidin intervention in vivo and in vitro. In addition, hesperidin could inhibit the IL6/STAT3 signaling pathway. Furthermore, suppression of the IL-6/STAT3 signaling pathway by pretreatment with the IL-6 inhibitor LMT-28 attenuating effect of hesperidin on fibroblast senescence in vitro.

CONCLUSIONS

These data illustrated that hesperidin may be potentially used in the treatment of IPF based on its ability to inhibit lung fibroblast senescence.

Noncoding RNAs: Master Regulator of Fibroblast to Myofibroblast Transition in Fibrosis

Myofibroblasts escape apoptosis and proliferate abnormally under pathological conditions, especially fibrosis; they synthesize and secrete a large amount of extracellular matrix (ECM), such as α-SMA and collagen, which leads to the distortion of organ parenchyma structure, an imbalance in collagen deposition and degradation, and the replacement of parenchymal cells by fibrous connective tissues. Fibroblast to myofibroblast transition (FMT) is considered to be the main source of myofibroblasts. Therefore, it is crucial to explore the influencing factors regulating the process of FMT for the prevention, treatment, and diagnosis of FMT-related diseases. In recent years, non-coding RNAs, including microRNA, long non-coding RNAs, and circular RNAs, have attracted extensive attention from scientists due to their powerful regulatory functions, and they have been found to play a vital role in regulating FMT. In this review, we summarized ncRNAs which regulate FMT during fibrosis and found that they mainly regulated signaling pathways, including TGF-β/Smad, MAPK/P38/ERK/JNK, PI3K/AKT, and WNT/β-catenin. Furthermore, the expression of downstream transcription factors can be promoted or inhibited, indicating that ncRNAs have the potential to be a new therapeutic target for FMT-related diseases.

N-acetylglucosamine-bearing polymers mimicking O-GlcNAc-modified proteins elicit anti-fibrotic activities in myofibroblasts and activated stellate cells

O-linked β-N-acetylglucosamine (O-GlcNAc)-modified proteins are post-translationally modified with GlcNAc conjugated to serine and threonine residues. This modification is associated with various physiological functions such as serine and threonine phosphorylation and Notch signaling. Here, we demonstrated that O-GlcNAc-modified proteins leaked from dead cells and GlcNAc-bearing polymers mimicking the multivalent GlcNAc moiety of these proteins induced anti-fibrotic activities, such as the suppression of α-smooth muscle actin and collagen and the induction of matrix metalloprotease 1 in myofibroblasts. We have previously reported that O-GlcNAc-modified proteins and GlcNAc-bearing polymers could interact with cell surface vimentin and desmin. In the current study, it was demonstrated that a multivalent GlcNAc moiety structure of these molecules activated PI3K/Akt and p38MAPK pathway and elicited these anti-fibrotic activities in myofibroblasts by interacting with cell surface vimentin. Since the interaction of O-GlcNAc-modified proteins with desmin was observed in the fibrotic liver of carbon tetrachloride-treated mice via an in situ proximity ligation assay, it was assumed that the activated stellate cells could bind to the O-GlcNAc-modified proteins from the damaged hepatocytes. In addition, the administration of anti-O-GlcNAc antibody to inhibit the interaction exacerbated liver fibrosis in the mice. Moreover, administration of the GlcNAc-bearing polymers into carbon tetrachloride-treated mice could ameliorate liver fibrosis. Thus, O-GlcNAc-modified proteins leaked from dead cells can interact with myofibroblasts and activated stellate cells and function as fibrosis suppressors. Moreover, we anticipate that GlcNAc-bearing polymers mimicking O-GlcNAc-modified proteins will be applied as novel therapeutic tools for fibrosis.

STAT3 in porcine endometrium during early pregnancy induces changes in extracellular matrix components and promotes angiogenesis†

A molecular interaction between maternal endometrium and implanting conceptus can lead to activation of a variety of transcription factors that regulate expression of several genes necessary for the process of embryo implantation. While, signal transducer and activator of transcription 3 (STAT3) is responsible for decidualization and epithelial remodeling in humans and mice, its role in porcine endometrium has not been explored before. In the present study, we observed a pregnancy dependent increase in gene and protein expression of STAT3. Phosphorylated STAT3 was predominantly present in the endometrium of pregnant animals in luminal and glandular epithelium and in the endothelium of blood vessels with a weak staining in stromal cells. Interleukins, IL-1β and IL-6, and epidermal growth factor (EGF)-induced STAT3 expression and phosphorylation in endometrial explants collected on Day 13 of the estrous cycle. Biological significance of STAT3 was evaluated by blocking its phosphorylation with STAT3-specific inhibitor, Stattic. Using porcine extracellular matrix (ECM) and adhesion molecule array, EGF was shown to induce changes in gene expression of ECM components: MMP1, MMP3, MMP12, LAMA1, SELL, and ICAM1, which was abrogated in the presence of Stattic. Transcriptional activity of STAT3 was observed in promoter regions of MMP3 and MMP12. Additionally, IL-6-induced STAT3 phosphorylation upregulated VEGF and VCAM1 abundances in endometrial-endothelial cells (EEC). Moreover, IL-6 resulted in an increase in EEC proliferation and capillary formation which was reversed in the presence of Stattic. Results of present study reveal a role for STAT3 phosphorylation in regulating extracellular matrix remodeling and angiogenesis in porcine endometrium to facilitate embryo implantation.

Chemotherapy as a regulator of extracellular matrix-cell communication: Implications in therapy resistance

The development of most solid cancers, including pancreatic, breast, lung, liver, and ovarian cancer, involves a desmoplastic reaction: a process of major remodeling of the extracellular matrix (ECM) affecting the ECM composition, mechanics, and microarchitecture. These properties of the ECM influence key cancer cell functions, including treatment resistance. Furthermore, emerging data show that various chemotherapeutic treatments lead to alterations in ECM features and ECM-cell communication. Here, we summarize the current knowledge around the effects of chemotherapy on both the ECM remodeling and ECM-cell signaling and discuss the implications of these alterations on distinct mechanisms of chemoresistance. Additionally, we provide an overview of current therapeutic strategies and ongoing clinical trials utilizing anti-cancer drugs to target the ECM-cell communication and explore the future challenges of these strategies.

Identification of the molecular mechanism and candidate markers for diabetic nephropathy

Background

Diabetic nephropathy (DN) is one of the most common complications in diabetic patients. New strategies are needed to delay the occurrence and development of this pathology.

Methods

Differentially expressed genes (DEGs) in glomeruli and renal tubules were identified using the GSE30122 dataset, and a co-expression network was constructed to identify the hub genes of modules. The biological function and signaling pathway of the module genes were also analyzed. In addition, the expression of 24 immune cells and the area under the receiver operating characteristic (ROC) curve (AUC) values of the hub genes were also calculated.

Results

A total of 1,778 DEGs were isolated from glomeruli and 1,996 DEGs were isolated from renal tubules. Nine modules and their hub genes were identified using the co-expression network. Enrichment analysis showed that the module genes were mainly enriched in immune inflammation and oxidative stress. The expressions of B cells, activated dendritic cell, and T cells in the glomeruli and renal tubules of DN patients were higher than those in the controls, and the correlation between these immune cells was the strongest. Collagen type I alpha 2 chain (COL1A2), the hub gene of the brown module, had the highest AUC values and may have a better clinical diagnostic ability.

Conclusions

In conclusion, the module genes and related biological functions and signaling pathways found in this study can deepen our understanding of the molecular mechanism of DN progression. COL1A2 may be a potential biomarker for DN.

Study of the colonic epithelial-mesenchymal dialogue through establishment of two activated or not mesenchymal cell lines: Activated and resting ones differentially modulate colonocytes in co-culture

Continuous and rapid renewal of the colonic epithelium is crucial to resist the plethora of luminal deleterious agents. Subepithelial fibroblasts contribute to this turnover by regulating epithelial proliferation and differentiation. However, when intestinal homeostasis is disturbed, fibroblasts can acquire an activated phenotype and play a major role in the progression of intestinal pathologies. To evaluate the involvement of fibroblasts in the regulation of colonocytes under homeostatic or pathological conditions, we established resting and activated conditionally immortalized fibroblast cell lines (nF and mF) from mouse colonic mucosa. We then studied the epithelial-mesenchymal interactions between activated or resting fibroblasts and the normal mouse colonocytes (Co) using a co-culture model. Both fibroblastic cell lines were characterized by RT-qPCR, western blot and immunofluorescence assay. Our results showed that nF and mF cells were positive for fibroblastic markers such as vimentin and collagen 1, and negative for cytokeratin 18 and E-cadherin, attesting to their fibroblastic type. They also expressed proteins characteristic of the epithelial stem cell niche such as Grem1, CD90 or Wnt5a. Only rare nF fibroblasts were positive for α-SMA, whereas all mF fibroblasts strongly expressed this marker, supporting that mF cells were activated fibroblasts/myofibroblasts. In coculture, nF fibroblasts and Co cells strongly interacted via paracrine exchanges resulting in BMP4 production in nF fibroblasts, activation of BMP signaling in Co colonocytes, and decreased growth of colonocytes. Activated-type mF fibroblasts did not exert the same effects on Co cells, allowing colonocytes free to proliferate. In conclusion, these two colonic fibroblast lines, associated with Co cells in coculture, should allow to better understand the role of mesenchymal cells in the preservation of homeostasis and the development of intestinal pathologies.

Relaxin Affects Airway Remodeling Genes Expression through Various Signal Pathways Connected with Transcription Factors

Fibrosis is one of the parameters of lung tissue remodeling in asthma. Relaxin has emerged as a natural suppressor of fibrosis, showing efficacy in the prevention of a multiple models of fibrosis. Therefore, the aim of this study was to analyze the aptitudes of relaxin, in the context of its immunomodulatory properties, in the development of airway remodeling. WI-38 and HFL1 fibroblasts, as well as epithelial cells (NHBE), were incubated with relaxin. Additionally, remodeling conditions were induced with two serotypes of rhinovirus (HRV). The expression of the genes contributing to airway remodeling were determined. Moreover, NF-κB, c-Myc, and STAT3 were knocked down to analyze the pathways involved in airway remodeling. Relaxin decreased the mRNA expression of collagen I and TGF-β and increased the expression of MMP-9 (p < 0.05). Relaxin also decreased HRV-induced expression of collagen I and α-SMA (p < 0.05). Moreover, all the analyzed transcription factors—NF-κB, c-Myc, and STAT3—have shown its influence on the pathways connected with relaxin action. Though relaxin requires further study, our results suggest that this natural compound offers great potential for inhibition of the development, or even reversing, of factors related to airway remodeling. The presented contribution of the investigated transcription factors in this process additionally increases its potential possibilities through a variety of its activity pathways.

Preclinical advances and the immunophysiology of a new therapeutic chagas disease vaccine

INTRODUCTION

Chronic infection with the protozoal parasite Trypanosoma cruzi leads to a progressive cardiac disease, known as chronic Chagasic cardiomyopathy (CCC). A new therapeutic Chagas disease vaccine is in development to augment existing antiparasitic chemotherapy drugs.

AREAS COVERED

We report on our current understanding of the underlying immunologic and physiologic mechanisms that lead to CCC, including parasite immune escape mechanisms that allow persistence and the subsequent inflammatory and fibrotic processes that lead to clinical disease. We report on vaccine design and the observed immunotherapeutic effects including induction of a balanced T_H1/T_H2/T_H17 immune response that leads to reduced parasite burdens and tissue pathology. Further, we report vaccine-linked chemotherapy, a dose sparing strategy to further reduce parasite burdens and tissue pathology.

EXPERT OPINION

Our vaccine-linked chemotherapeutic approach is a multimodal treatment strategy, addressing both the parasite persistence and the underlying deleterious host inflammatory and fibrotic responses that lead to cardiac dysfunction. In targeting treatment towards patients with chronic indeterminate or early determinate Chagas disease, this vaccine-linked chemotherapeutic approach will be highly economical and will reduce the global disease burden and deaths due to CCC.

TSP1 promotes fibroblast proliferation and extracellular matrix deposition via the IL6/JAK2/STAT3 signalling pathway in keloids

Keloids are benign fibroproliferative diseases with abnormally proliferated bulges beyond the edge of the skin lesions, and they are characterized by uncontrolled fibroblast proliferation and excessive extracellular matrix deposition in the dermis. However, the definite mechanisms that increase fibroblast proliferation and collagen deposition in keloids remain unclear. Thrombospondin 1 (TSP1) has been suggested to play an important role in wound healing and fibrotic disorders, but its role in keloids is unknown. In this study, we aimed to clarify the specific role of TSP1 in keloids and explore the potential mechanism. Our results demonstrated that TSP1 was highly expressed in keloid lesions compared to normal skin. Knockdown of TSP1 in keloid fibroblasts decreased cell proliferation and collagen I deposition. Exogenous TSP1 treatment increased cell proliferation and collagen I deposition in normal fibroblasts. We further investigated the underlying mechanism and found that TSP1 promoted fibroblast proliferation and extracellular matrix deposition by upregulating the IL6/JAK2/STAT3 pathway. Moreover, we verified that TSP1 expression was positively correlated with IL6/STAT3 signalling activity in keloids. Taken together, our findings indicate that TSP1 promotes keloid development via the IL6/JAK2/STAT3 signalling pathway and blocking TSP1 may represent a potential strategy for keloid therapy.

G Protein-Coupled Receptor Kinase 2 as Novel Therapeutic Target in Fibrotic Diseases

G protein-coupled receptor kinase 2 (GRK2), an important subtype of GRKs, specifically phosphorylates agonist-activated G protein-coupled receptors (GPCRs). Besides, current research confirms that it participates in multiple regulation of diverse cells via a non-phosphorylated pathway, including interacting with various non-receptor substrates and binding partners. Fibrosis is a common pathophysiological phenomenon in the repair process of many tissues due to various pathogenic factors such as inflammation, injury, drugs, etc. The characteristics of fibrosis are the activation of fibroblasts leading to myofibroblast proliferation and differentiation, subsequent aggerate excessive deposition of extracellular matrix (ECM). Then, a positive feedback loop is occurred between tissue stiffness caused by ECM and fibroblasts, ultimately resulting in distortion of organ architecture and function. At present, GRK2, which has been described as a multifunctional protein, regulates copious signaling pathways under pathophysiological conditions correlated with fibrotic diseases. Along with GRK2-mediated regulation, there are diverse effects on the growth and apoptosis of different cells, inflammatory response and deposition of ECM, which are essential in organ fibrosis progression. This review is to highlight the relationship between GRK2 and fibrotic diseases based on recent research. It is becoming more convincing that GRK2 could be considered as a potential therapeutic target in many fibrotic diseases.

Curcumin modulates airway remodelling-contributing genes-the significance of transcription factors

Bronchial epithelial cells and fibroblasts play an essential role in airway remodelling, due to their protective and secretory functions. There are many studies proving that infection caused by human rhinovirus may contribute to the process of airway remodelling. The beneficial properties of curcumin, the basic ingredient of turmeric, have been proved in many studies. Therefore, the aim of this study was the evaluation of curcumin immunomodulatory properties in development of airway remodelling. Fibroblasts (WI‐38 and HFL1) and epithelial cells (NHBE) were incubated with curcumin. Additionally, remodelling conditions were induced with rhinovirus (HRV). Airway remodelling genes were determined by qPCR and immunoblotting. Moreover, NF‐κB, c‐Myc and STAT3 were silenced to analyse the pathways involved in airway remodelling. Curcumin reduced the expression of the genes analysed, especially MMP‐9, TGF‐β and collagen I. Moreover, curcumin inhibited the HRV‐induced expression of MMP‐9, TGF‐β, collagen I and LTC4S (p < 0.05). NF‐κB, c‐Myc and STAT3 changed their course of expression. Concluding, our study shows that curcumin significantly downregulated gene expression related to the remodelling process, which is dependent on NF‐κB and, partially, on c‐Myc and STAT3. The results suggest that the remodelling process may be limited and possibly prevented, however this issue requires further research.

ROCK2 inhibition attenuates profibrogenic immune cell function to reverse thioacetamide-induced liver fibrosis

Background & Aims

Fibrosis, the primary cause of morbidity in chronic liver disease, is induced by pro-inflammatory cytokines, immune cell infiltrates, and tissue resident cells that drive excessive myofibroblast activation, collagen production, and tissue scarring. Rho-associated kinase 2 (ROCK2) regulates key pro-fibrotic pathways involved in both inflammatory reactions and altered extracellular matrix remodelling, implicating this pathway as a potential therapeutic target.

Methods

We used the thioacetamide-induced liver fibrosis model to examine the efficacy of administration of the selective ROCK2 inhibitor KD025 to prevent or treat liver fibrosis and its impact on immune composition and function.

Results

Prophylactic and therapeutic administration of KD025 effectively attenuated thioacetamide-induced liver fibrosis and promoted fibrotic regression. KD025 treatment inhibited liver macrophage tumour necrosis factor production and disrupted the macrophage niche within fibrotic septae. ROCK2 targeting in vitro directly regulated macrophage function through disruption of signal transducer and activator of transcription 3 (STAT3)/cofilin signalling pathways leading to the inhibition of pro-inflammatory cytokine production and macrophage migration. In vivo, KDO25 administration significantly reduced STAT3 phosphorylation and cofilin levels in the liver. Additionally, livers exhibited robust downregulation of immune cell infiltrates and diminished levels of retinoic acid receptor-related orphan receptor gamma (RORγt) and B-cell lymphoma 6 (Bcl6) transcription factors that correlated with a significant reduction in liver IL-17, splenic germinal centre numbers and serum IgG.

Conclusions

As IL-17 and IgG–Fc binding promote pathogenic macrophage differentiation, together our data demonstrate that ROCK2 inhibition prevents and reverses liver fibrosis through direct and indirect effects on macrophage function and highlight the therapeutic potential of ROCK2 inhibition in liver fibrosis.

Lay summary

By using a clinic-ready small-molecule inhibitor, we demonstrate that selective ROCK2 inhibition prevents and reverses hepatic fibrosis through its pleiotropic effects on pro-inflammatory immune cell function. We show that ROCK2 mediates increased IL-17 production, antibody production, and macrophage dysregulation, which together drive fibrogenesis in a model of chemical-induced liver fibrosis. Therefore, in this study, we not only highlight the therapeutic potential of ROCK2 targeting in chronic liver disease but also provide previously undocumented insights into our understanding of cellular and molecular pathways driving the liver fibrosis pathology.

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ROCK2 inhibition with the small-molecule inhibitor KD025 prevents and reverses hepatoxin-induced liver fibrosis.

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ROCK2 inhibition attenuates profibrogenic immune function.

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KD025 exerts direct effects on liver macrophages resulting in decreased TNF secretion and impeded migration.

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KD025 administration attenuates T cell IL-17 production and B-cell IgG production, which indirectly contributes to downregulation of profibrogenic macrophage function.

Exploiting the STAT3 Nexus in Cancer-Associated Fibroblasts to Improve Cancer Therapy

The tumor microenvironment (TME) is composed of a heterogenous population of cells that exist alongside the extracellular matrix and soluble components. These components can shape an environment that is conducive to tumor growth and metastatic spread. It is well-established that stromal cancer-associated fibroblasts (CAFs) in the TME play a pivotal role in creating and maintaining a growth-permissive environment for tumor cells. A growing body of work has uncovered that tumor cells recruit and educate CAFs to remodel the TME, however, the mechanisms by which this occurs remain incompletely understood. Recent studies suggest that the signal transducer and activator of transcription 3 (STAT3) is a key transcription factor that regulates the function of CAFs, and their crosstalk with tumor and immune cells within the TME. CAF-intrinsic STAT3 activity within the TME correlates with tumor progression, immune suppression and eventually the establishment of metastases. In this review, we will focus on the roles of STAT3 in regulating CAF function and their crosstalk with other cells constituting the TME and discuss the utility of targeting STAT3 within the TME for therapeutic benefit.

Identification of Impacted Pathways and Transcriptomic Markers as Potential Mediators of Pulmonary Fibrosis in Transgenic Mice Expressing Human IGFBP5

Pulmonary fibrosis is a serious disease characterized by extracellular matrix (ECM) component overproduction and remodeling. Insulin-like growth factor-binding protein 5 (IGFBP5) is a conserved member of the IGFBP family of proteins that is overexpressed in fibrotic tissues and promotes fibrosis. We used RNA sequencing (RNAseq) to identify differentially expressed genes (DEGs) between primary lung fibroblasts (pFBs) of homozygous (HOMO) transgenic mice expressing human IGFBP5 (hIGFBP5) and wild type mice (WT). The results of the differential expression analysis showed 2819 DEGs in hIGFBP5 pFBs. Functional enrichment analysis confirmed the pro-fibrotic character of IGFBP5 and revealed its impact on fundamental signaling pathways, including cytokine–cytokine receptor interaction, focal adhesion, AGE-RAGE signaling, calcium signaling, and neuroactive ligand-receptor interactions, to name a few. Noticeably, 7% of the DEGs in hIGFBP5-expressing pFBs are receptors and integrins. Furthermore, hub gene analysis revealed 12 hub genes including Fpr1, Bdkrb2, Mchr1, Nmur1, Cnr2, P2ry14, and Ptger3. Validation assays were performed to complement the RNAseq data. They confirmed significant differences in the levels of the corresponding proteins in cultured pFBs. Our study provides new insights into the molecular mechanism(s) of IGFBP5-associated pulmonary fibrosis through possible receptor interactions that drive fibrosis and tissue remodeling.

IL-35 subunit EBI3 alleviates bleomycin-induced pulmonary fibrosis via suppressing DNA enrichment of STAT3

BACKGROUND

IL-35 subunit EBI3 is up-regulated in pulmonary fibrosis tissues. In this study, we investigated the pathological role of EBI3 in pulmonary fibrosis and dissected the underlying molecular mechanism.

METHODS

Bleomycin-induced pulmonary fibrosis mouse model was established, and samples were performed gene expression analyses through RNAseq, qRT-PCR and Western blot. Wild type and EBI3 knockout mice were exposed to bleomycin to investigate the pathological role of IL-35, via lung function and gene expression analyses. Primary lung epithelial cells were used to dissect the regulatory mechanism of EBI3 on STAT1/STAT4 and STAT3.

RESULTS

IL-35 was elevated in both human and mouse with pulmonary fibrosis. EBI3 knockdown aggravated the symptoms of pulmonary fibrosis in mice. EBI3 deficiency enhanced the expressions of fibrotic and extracellular matrix-associated genes. Mechanistically, IL-35 activated STAT1 and STAT4, which in turn suppressed DNA enrichment of STAT3 and inhibited the fibrosis process.

CONCLUSION

IL-35 might be one of the potential therapeutic targets for bleomycin-induced pulmonary fibrosis.

Interleukin-31 promotes fibrosis and T helper 2 polarization in systemic sclerosis

Systemic sclerosis (SSc) is a chronic multisystem disorder characterized by fibrosis and autoimmunity. Interleukin (IL)-31 has been implicated in fibrosis and T helper (Th) 2 immune responses, both of which are characteristics of SSc. The exact role of IL-31 in SSc pathogenesis is unclear. Here we show the overexpression of IL-31 and IL-31 receptor A (IL-31RA) in dermal fibroblasts (DFs) from SSc patients. We elucidate the dual role of IL-31 in SSc, where IL-31 directly promotes collagen production in DFs and indirectly enhances Th2 immune responses by increasing pro-Th2 cytokine expression in DFs. Furthermore, blockade of IL-31 with anti-IL-31RA antibody significantly ameliorates fibrosis and Th2 polarization in a mouse model of SSc. Therefore, in addition to defining IL-31 as a mediator of fibrosis and Th2 immune responses in SSc, our study provides a rationale for targeting the IL-31/IL-31RA axis in the treatment of SSc.

Systemic sclerosis (SSc) disease involves multisystem fibrosis and autoimmunity with limited treatment options. Here the authors demonstrate that IL-31 and IL-31RA are overexpressed in dermal fibroblasts from SSc patients and show that fibrosis and cytokine release can be reduced upon blocking of IL-31/IL-31RA.

Identification of hub genes and key pathways of paraquat-induced human embryonic pulmonary fibrosis by bioinformatics analysis and in vitro studies

Objective: Paraquat (N,N0-dimethyl-4,40-bipyridinium dichloride;PQ) is a highly toxic pesticide, which usually leads to acute lung injury and subsequent development of pulmonary fibrosis. The exact mechanism underlying PQ-induced lung fibrosis remain largely unclear and as yet, no specific treatment drugs have been approved. Our study aimed to identify its potential mechanisms of PQ-induced fibrosis through a modeling study in vitro studies and bioinformatics analysis.

Methods: Gene expression datasets associated with PQ-induced lung fibrosis were obtained from the Gene Expression Omnibus, wherefrom differentially expressed genes (DEGs) were identified using GEO2R. Functional enrichment analyses were performed using the Database for Annotation Visualization and Integrated Discovery. The DEGs analyzed by a protein–protein interaction network was constructed with the Search Tool for the Retrieval of Interacting Genes database. MCODE, a Cytoscape plugin, was subsequently used to identify the most significant modules. The expression of the key genes in PQ-induced pulmonary fibrotic tissues was verified by reverse transcription-quantitative PCR (RT-qPCR).

Results: Two datasets were analyzed and revealed 92 overlapping DEGs. Functional analysis demonstrated that these 92 DEGs were enriched in the ‘TNF signaling pathway’, ‘CXCR chemokine receptor binding’, and ‘core promoter binding’. Moreover, nine hub genes were identified from the protein–protein interaction network formed from the DEGs. These results suggested that the TNF signaling pathway and nine hub genes are possibly involved in PQ-induced lung fibrosis progression.

Conclusions: This integrative analysis identified candidate genes and pathways potentially involved in PQ-induced lung fibrosis, and could benefit future development of novel approaches for controlling and treating this disease.

Signal Transducer and Activator of Transcription-3 Modulation of Cardiac Pathology in Chronic Chagasic Cardiomyopathy

Chronic Chagasic cardiomyopathy (CCC) is a severe clinical manifestation that develops in 30%–40% of individuals chronically infected with the protozoal parasite Trypanosoma cruzi and is thus an important public health problem. Parasite persistence during chronic infection drives pathologic changes in the heart, including myocardial inflammation and progressive fibrosis, that contribute to clinical disease. Clinical manifestations of CCC span a range of symptoms, including cardiac arrhythmias, thromboembolic disease, dilated cardiomyopathy, and heart failure. This study aimed to investigate the role of signal transducer and activator of transcription-3 (STAT3) in cardiac pathology in a mouse model of CCC. STAT3 is a known cellular mediator of collagen deposition and fibrosis. Mice were infected with T. cruzi and then treated daily from 70 to 91 days post infection (DPI) with TTI-101, a small molecule inhibitor of STAT3; benznidazole; a combination of benznidazole and TTI-101; or vehicle alone. Cardiac function was evaluated at the beginning and end of treatment by echocardiography. By the end of treatment, STAT3 inhibition with TTI-101 eliminated cardiac fibrosis and fibrosis biomarkers but increased cardiac inflammation; serum levels of interleukin-6 (IL-6), and IFN−γ; cardiac gene expression of STAT1 and nuclear factor-κB (NF-κB); and upregulation of IL-6 and Type I and Type II IFN responses. Concurrently, decreased heart function was measured by echocardiography and myocardial strain. These results indicate that STAT3 plays a critical role in the cardiac inflammatory–fibrotic axis during CCC.

New Insights into Profibrotic Myofibroblast Formation in Systemic Sclerosis: When the Vascular Wall Becomes the Enemy

In systemic sclerosis (SSc), abnormalities in microvessel morphology occur early and evolve into a distinctive vasculopathy that relentlessly advances in parallel with the development of tissue fibrosis orchestrated by myofibroblasts in nearly all affected organs. Our knowledge of the cellular and molecular mechanisms underlying such a unique relationship between SSc-related vasculopathy and fibrosis has profoundly changed over the last few years. Indeed, increasing evidence has suggested that endothelial-to-mesenchymal transition (EndoMT), a process in which profibrotic myofibroblasts originate from endothelial cells, may take center stage in SSc pathogenesis. While in arterioles and small arteries EndoMT may lead to the accumulation of myofibroblasts within the vessel wall and development of fibroproliferative vascular lesions, in capillary vessels it may instead result in vascular destruction and formation of myofibroblasts that migrate into the perivascular space with consequent tissue fibrosis and microvessel rarefaction, which are hallmarks of SSc. Besides endothelial cells, other vascular wall-resident cells, such as pericytes and vascular smooth muscle cells, may acquire a myofibroblast-like synthetic phenotype contributing to both SSc-related vascular dysfunction and fibrosis. A deeper understanding of the mechanisms underlying the differentiation of myofibroblasts inside the vessel wall provides the rationale for novel targeted therapeutic strategies for the treatment of SSc.

The Role of Pro-fibrotic Myofibroblasts in Systemic Sclerosis: from Origin to Therapeutic Targeting

Systemic sclerosis (SSc, scleroderma) is a complex connective tissue disorder characterized by multisystem clinical manifestations resulting from immune dysregulation/autoimmunity, vasculopathy and, most notably, progressive fibrosis of the skin and internal organs. In recent years, it has emerged that the main drivers of SSc-related tissue fibrosis are myofibroblasts, a type of mesenchymal cells with both the extracellular matrix-synthesizing features of fibroblasts and the cytoskeletal characteristics of contractile smooth muscle cells. The accumulation and persistent activation of pro-fibrotic myofibroblasts during SSc development and progression result into elevated mechanical stress and reduced matrix plasticity within the affected tissues and may be ascribed to a reduced susceptibility of these cells to pro-apoptotic stimuli, as well as their increased formation from tissue-resident fibroblasts or transition from different cell types. Given the crucial role of myofibroblasts in SSc pathogenesis, finding the way to inhibit myofibroblast differentiation and accumulation by targeting their formation, function and survival may represent an effective approach to hamper the fibrotic process or even halt or reverse established fibrosis. In this review, we discuss the role of myofibroblasts in SSc-related fibrosis, with a special focus on their cellular origin and the signaling pathways implicated in their formation and persistent activation. Furthermore, we provide an overview of potential therapeutic strategies targeting myofibroblasts that may be able to counteract fibrosis in this pathological condition.

Germline STAT3 gain-of-function mutations in primary immunodeficiency: Impact on the cellular and clinical phenotype

Signal transducer and activator of transcription 3 (STAT3) is a key transcription factor involved in regulation of immune cell activation and differentiation. Recent discoveries highlight the role of germline activating STAT3 mutations in inborn errors of immunity characterized by early-onset multi-organ autoimmunity and lymphoproliferation. Much progress has been made in defining the clinical spectrum of STAT3 GOF disease and unraveling the molecular and cellular mechanisms underlying this disease. In this review, we summarize our current understanding of the disease and discuss the clinical phenotype, diagnostic approach, cellular and molecular effects of STAT3 GOF mutations and therapeutic concepts for these patients.

Elucidating the cellular mechanism for E2-induced dermal fibrosis

BACKGROUND

Both TGFβ and estradiol (E2), a form of estrogen, are pro-fibrotic in the skin. In the connective tissue disease, systemic sclerosis (SSc), both TGFβ and E2 are likely pathogenic. Yet the regulation of TGFβ in E2-induced dermal fibrosis remains ill-defined. Elucidating those regulatory mechanisms will improve the understanding of fibrotic disease pathogenesis and set the stage for developing potential therapeutics. Using E2-stimulated primary human dermal fibroblasts in vitro and human skin tissue ex vivo, we identified the important regulatory proteins for TGFβ and investigated the extracellular matrix (ECM) components that are directly stimulated by E2-induced TGFβ signaling.

METHODS

We used primary human dermal fibroblasts in vitro and human skin tissue ex vivo stimulated with E2 or vehicle (ethanol) to measure TGFβ1 and TGFβ2 levels using quantitative PCR (qPCR). To identify the necessary cell signaling proteins in E2-induced TGFβ1 and TGFβ2 transcription, human dermal fibroblasts were pre-treated with an inhibitor of the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathway, U0126. Finally, human skin tissue ex vivo was pre-treated with SB-431542, a TGFβ receptor inhibitor, and ICI 182,780, an estrogen receptor α (ERα) inhibitor, to establish the effects of TGFβ and ERα signaling on E2-induced collagen 22A1 (Col22A1) transcription.

RESULTS

We found that expression of TGFβ1, TGFβ2, and Col22A1, a TGFβ-responsive gene, is induced in response to E2 stimulation. Mechanistically, Col22A1 induction was blocked by SB-431542 and ICI 182,780 despite E2 stimulation. Additionally, inhibiting E2-induced ERK/MAPK activation and early growth response 1 (EGR1) transcription prevents the E2-induced increase in TGFβ1 and TGFβ2 transcription and translation.

CONCLUSIONS

We conclude that E2-induced dermal fibrosis occurs in part through induction of TGFβ1, 2, and Col22A1, which is regulated through EGR1 and the MAPK pathway. Thus, blocking estrogen signaling and/or production may be a novel therapeutic option in pro-fibrotic diseases.

Resistin induces cardiac fibroblast-myofibroblast differentiation through JAK/STAT3 and JNK/c-Jun signaling

Cardiac fibrosis is characterized by excessive deposition of extracellular matrix proteins and myofibroblast differentiation. Our previous findings have implicated resistin in cardiac fibrosis; however, the molecular mechanisms underlying this process are still unclear. Here we investigated the role of resistin in fibroblast-to-myofibroblast differentiation and elucidated the pathways involved in this process. Fibroblast-to-myofibroblast transdifferentiation was induced with resistin or TGFβ1 in NIH-3T3 and adult cardiac fibroblasts. mRNA and protein expression of fibrotic markers were analyzed by qPCR and immunoblotting. Resistin-knockout mice, challenged with a high-fat diet (HFD) for 20 weeks to stimulate cardiac impairment, were analyzed for cardiac function and fibrosis using histologic and molecular methods. Cardiac fibroblasts stimulated with resistin displayed increased fibroblast-to-myofibroblast conversion, with increased levels of αSma, col1a1, Fn, Ccn2 and Mmp9, with remarkable differences in the actin network appearance. Mechanistically, resistin promotes fibroblast-to-myofibroblast transdifferentiation and fibrogenesis via JAK2/STAT3 and JNK/c-Jun signaling pathways, independent of TGFβ1. Resistin-null mice challenged with HFD showed an improvement in cardiac function and a decrease in tissue fibrosis and reduced mRNA levels of fibrogenic markers. These findings are the first to delineate the role of resistin in the process of cardiac fibroblast-to-myofibroblast differentiation via JAK/STAT3 and JNK/c-Jun pathways, potentially leading to stimulation of cardiac fibrosis.

Interleukin-38 ameliorates poly(I:C) induced lung inflammation: therapeutic implications in respiratory viral infections

Interleukin-38 has recently been shown to have anti-inflammatory properties in lung inflammatory diseases. However, the effects of IL-38 in viral pneumonia remains unknown. In the present study, we demonstrate that circulating IL-38 concentrations together with IL-36α increased significantly in influenza and COVID-19 patients, and the level of IL-38 and IL-36α correlated negatively and positively with disease severity and inflammation, respectively. In the co-cultured human respiratory epithelial cells with macrophages to mimic lung microenvironment in vitro, IL-38 was able to alleviate inflammatory responses by inhibiting poly(I:C)-induced overproduction of pro-inflammatory cytokines and chemokines through intracellular STAT1, STAT3, p38 MAPK, ERK1/2, MEK, and NF-κB signaling pathways. Intriguingly, transcriptomic profiling revealed that IL-38 targeted genes were associated with the host innate immune response to virus. We also found that IL-38 counteracts the biological processes induced by IL-36α in the co-culture. Furthermore, the administration of recombinant IL-38 could mitigate poly I:C-induced lung injury, with reduced early accumulation of neutrophils and macrophages in bronchoalveolar lavage fluid, activation of lymphocytes, production of pro-inflammatory cytokines and chemokines and permeability of the alveolar-epithelial barrier. Taken together, our study indicates that IL-38 plays a crucial role in protection from exaggerated pulmonary inflammation during poly(I:C)-induced pneumonia, thereby providing the basis of a novel therapeutic target for respiratory viral infections.

Small-Dose Sunitinib Modulates p53, Bcl-2, STAT3, and ERK1/2 Pathways and Protects against Adenine-Induced Nephrotoxicity

The therapeutic use of numerous pharmacological agents may be limited due to their nephrotoxicity and associated kidney injury. The aim of our study is to test the hypothesis that the blockade of tyrosine kinase-linked receptors signaling protects against chemically induced nephrotoxicity. To test our hypothesis, we investigated sunitinib as an inhibitor for tyrosine kinase signaling for both vascular endothelial growth factor receptor (VEGFR) and platelet-derived growth factor receptors (PDGFR) against adenine-induced nephrotoxicity. Four groups of adult male Swiss albino mice were investigated: normal group, adenine group, sunitinib group, and the adenine+sunitinib group that received concurrent administration for both adenine and sunitinib. Kidney function and oxidative stress biomarkers were analyzed. Tubular injury and histopathological changes were examined. Renal expression of B-cell lymphoma-2 (Bcl-2), the tumor suppressor p53, transforming growth factor beta-1 (TGF-β1), phospho-extracellular signal-regulated kinase 1/2 (p-ERK1/2), and phospho-signal transducer and activator of transcription (phospho-STAT3) were measured. The results obtained showed significant improvement (p < 0.05) in kidney function and antioxidant biomarkers in the adenine+sunitinib group. Kidney fibrosis and tubular injury scores were significantly (p < 0.05) less in the adenine+sunitinib group and that of p53 expression as well. Furthermore, sunitinib decreased (p < 0.5) renal levels of TGF-β1, p-ERK1/2, and phospho-STAT3 while elevating Bcl-2 expression score. In conclusion, sunitinib diminished adenine-induced nephrotoxicity through interfering with profibrogenic pathways, activating anti-apoptotic mechanisms, and possessing potential antioxidant capabilities.

Cross-talk between Janus kinase-signal transducer and activator of transcription pathway and transforming growth factor beta pathways and increased collagen1A1 production in uterine leiomyoma cells

OBJECTIVE

To characterize the potential interaction between interleukin-6 (IL6), Janus kinase (JAK)-signal transducer and activator of transcription (STAT)-3 (JAK/STAT3) pathway, and Transforming growth factor beta (TGFβ)-3 , and to determine whether such cross-talk was a contributing factor in the dysregulation of type I collagen production in leiomyomas.

DESIGN

Laboratory study.

SETTING

University research laboratory.

PATIENTS

None.

INTERVENTIONS

Exposure of leiomyoma and myometrial cell lines to IL6 and STAT3 activators/inhibitors. Western immunoblot analysis and immunohistochemistry.

MAIN OUTCOME MEASURES

Expression of STAT3, pSTAT3, SOCS3, COL1A1, and TGFb3.

RESULTS

We observed that IL6 increased pSTAT3 as well as collagen1A1 in uterine leiomyoma cells. Direct activation of the JAK/STAT3 pathway increased collagen1A1 production in leiomyoma cells, whereas inhibition of the pathway significantly decreased collagen1A1 production. We further observed that modulation of the JAK/STAT3 pathway also increased the expression of TGFβ3 protein. Leiomyoma cells exposed to TGFβ3 demonstrated a significant decrease in pSTAT3 protein. Myometrial cells demonstrated a less sensitive response to STAT3 modulation and collagen production.

CONCLUSION

Cross-talk between the TGFβ pathway and JAK/STAT3 pathway contributes to the fibrotic nature of uterine leiomyomas.

Tocilizumab in systemic sclerosis: a randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

A phase 2 trial of tocilizumab showed preliminary evidence of efficacy in systemic sclerosis. We assessed skin fibrosis and systemic sclerosis-associated interstitial lung disease (SSc-ILD) in a phase 3 trial to investigate the safety and efficacy of tocilizumab, an anti-interleukin-6 receptor antibody, in the treatment of systemic sclerosis.

METHODS

In this multicentre, randomised, double-blind, placebo-controlled, phase 3 trial, participants were recruited from 75 sites in 20 countries across Europe, North America, Latin America, and Japan. Adults with diffuse cutaneous systemic sclerosis for 60 months or less and a modified Rodnan skin score (mRSS) of 10-35 at screening were randomly assigned (1:1) with a voice-web-response system to receive subcutaneous tocilizumab 162 mg or placebo weekly for 48 weeks, stratified by IL-6 levels; participants and investigators were masked to treatment group. The primary endpoint was the difference in change from baseline to week 48 in mRSS. Percentage of predicted forced vital capacity (FVC% predicted) at week 48, time to treatment failure, and patient-reported and physician-reported outcomes were secondary endpoints. This trial is registered with ClinicalTrials.gov (number NCT02453256) and is closed to accrual.

FINDINGS

Between Nov 20, 2015, and Feb 14, 2017, 210 individuals were randomly assigned to receive tocilizumab (n=104) or placebo (n=106). In the intention-to-treat population, least squares mean [LSM] change from baseline to week 48 in mRSS was -6·14 for tocilizumab and -4·41 for placebo (adjusted difference -1·73 [95% CI -3·78 to 0·32]; p=0·10). The shift in distribution of change from baseline in FVC% predicted at week 48 favoured tocilizumab (van Elteren nominal p=0·002 vs placebo), with a difference in LSM of 4·2 (95% CI 2·0-6·4; nominal p=0·0002), as did time to treatment failure (hazard ratio 0·63 [95% CI 0·37-1·06]; nominal p=0·08). Change in LSM from baseline to week 48 in Health Assessment Questionnaire-Disability Index and in patient-global and physician-global visual analogue scale assessments did not differ between tocilizumab and placebo. In the safety set, infections were the most common adverse events (54 [52%] of 104 participants in the tocilizumab group, 53 [50%] of 106 in the placebo group). Serious adverse events were reported in 13 participants treated with tocilizumab and 18 with placebo, primarily infections (three events, eight events) and cardiac events (two events, seven events).

INTERPRETATION

The primary skin fibrosis endpoint was not met. Findings for the secondary endpoint of FVC% predicted indicate that tocilizumab might preserve lung function in people with early SSc-ILD and elevated acute-phase reactants. Safety was consistent with the known profile of tocilizumab.

FUNDING

F Hoffmann-La Roche Ltd.

Targeting Janus Kinases and Signal Transducer and Activator of Transcription 3 to Treat Inflammation, Fibrosis, and Cancer: Rationale, Progress, and Caution

Before it was molecularly cloned in 1994, acute-phase response factor or signal transducer and activator of transcription (STAT)3 was the focus of intense research into understanding the mammalian response to injury, particularly the acute-phase response. Although known to be essential for liver production of acute-phase reactant proteins, many of which augment innate immune responses, molecular cloning of acute-phase response factor or STAT3 and the research this enabled helped establish the central function of Janus kinase (JAK) family members in cytokine signaling and identified a multitude of cytokines and peptide hormones, beyond interleukin-6 and its family members, that activate JAKs and STAT3, as well as numerous new programs that their activation drives. Many, like the acute-phase response, are adaptive, whereas several are maladaptive and lead to chronic inflammation and adverse consequences, such as cachexia, fibrosis, organ dysfunction, and cancer. Molecular cloning of STAT3 also enabled the identification of other noncanonical roles for STAT3 in normal physiology, including its contribution to the function of the electron transport chain and oxidative phosphorylation, its basal and stress-related adaptive functions in mitochondria, its function as a scaffold in inflammation-enhanced platelet activation, and its contributions to endothelial permeability and calcium efflux from endoplasmic reticulum. In this review, we will summarize the molecular and cellular biology of JAK/STAT3 signaling and its functions under basal and stress conditions, which are adaptive, and then review maladaptive JAK/STAT3 signaling in animals and humans that lead to disease, as well as recent attempts to modulate them to treat these diseases. In addition, we will discuss how consideration of the noncanonical and stress-related functions of STAT3 cannot be ignored in efforts to target the canonical functions of STAT3, if the goal is to develop drugs that are not only effective but safe. SIGNIFICANCE STATEMENT: Key biological functions of Janus kinase (JAK)/signal transducer and activator of transcription (STAT)3 signaling can be delineated into two broad categories: those essential for normal cell and organ development and those activated in response to stress that are adaptive. Persistent or dysregulated JAK/STAT3 signaling, however, is maladaptive and contributes to many diseases, including diseases characterized by chronic inflammation and fibrosis, and cancer. A comprehensive understanding of JAK/STAT3 signaling in normal development, and in adaptive and maladaptive responses to stress, is essential for the continued development of safe and effective therapies that target this signaling pathway.

COL4A1 promotes the growth and metastasis of hepatocellular carcinoma cells by activating FAK-Src signaling

BACKGROUND

Collagens are the most abundant proteins in extra cellular matrix and important components of tumor microenvironment. Recent studies have showed that aberrant expression of collagens can influence tumor cell behaviors. However, their roles in hepatocellular carcinoma (HCC) are poorly understood.

METHODS

In this study, we screened all 44 collagen members in HCC using whole transcriptome sequencing data from the public datasets, and collagen type IV alpha1 chain (COL4A1) was identified as most significantly differential expressed gene. Expression of COL4A1 was detected in HCC samples by quantitative real-time polymerase chain reaction (qRT-PCR), western blot and immunohistochemistry (IHC). Finally, functions and potential mechanisms of COL4A1 were explored in HCC progression.

RESULTS

COL4A1 is the most significantly overexpressed collagen gene in HCC. Upregulation of COL4A1 facilitates the proliferation, migration and invasion of HCC cells through FAK-Src signaling. Expression of COL4A1 is upregulated by RUNX1 in HCC. HCC cells with high COL4A1 expression are sensitive to the treatment with FAK or Src inhibitor.

CONCLUSION

COL4A1 facilitates growth and metastasis in HCC via activation of FAK-Src signaling. High level of COL4A1 may be a potential biomarker for diagnosis and treatment with FAK or Src inhibitor for HCC.

Intestinal ex vivo organoid culture reveals altered programmed crypt stem cells in patients with celiac disease

The ex vivo generation of gastrointestinal organoids from crypt stem cells opens up the possibility of new research approaches investigating gastrointestinal diseases. We used this technology to study differences between healthy controls and patients with celiac disease (CD). We noticed distinct dissimilarities in the phenotypes of organoids between our study groups and found considerable variations in their gene expression. Extracellular matrix genes involved in epithelial-mesenchymal transition are expressed most differently. In addition, we demonstrated epigenetic modifications that might be responsible for the different organoid gene expression thus accounting for a deranged crypt/villus axis development in CD. The organoids have proven valuable to demonstrate fundamental differences in duodenal derived organoids between healthy controls and patients with CD and thus are a suitable tool to gain new insights in pathogenesis of CD.

The JAK/STAT pathway is activated in systemic sclerosis and is effectively targeted by tofacitinib

Rationale

Fibrosis leads to failure of the skin, lungs, and other organs in systemic sclerosis; accounts for substantial morbidity and mortality; and lacks effective therapy. Myofibroblast activation underlies organ fibrosis, but the key extracellular cues driving persistence of the process remain incompletely characterized.

Objectives

The objectives were to evaluate activation of the IL6/JAK/STAT axis associated with fibrosis in skin and lung biopsies from systemic sclerosis patients and effects of the Food and Drug Administration-approved JAK/STAT inhibitor, tofacitinib, on skin and lung fibrosis in animal models.

Methods

Bioinformatic analysis showed that IL6/JAK/STAT3 and tofacitinib gene signatures were aberrant in biopsies from systemic sclerosis patients in four independent cohorts. The results were confirmed by JAK and STAT3 phosphorylation in both skin and lung biopsies from patients with systemic sclerosis. Furthermore, treatment of mice with the selective JAK inhibitor tofacitinib not only prevented bleomycin-induced skin and lung fibrosis but also reduced skin fibrosis in TSK1/+ mice.

Conclusion

These findings implicate the JAK/STAT pathway in systemic sclerosis skin and lung fibrosis and identify tofacitinib as a potential antifibrotic agent for the treatment of systemic sclerosis and other fibrotic diseases.

AAV1.SERCA2a Gene Therapy Reverses Pulmonary Fibrosis by Blocking the STAT3/FOXM1 Pathway and Promoting the SNON/SKI Axis

Inhibition of pulmonary fibrosis (PF) by restoring sarco/endoplasmic reticulum calcium ATPase 2a isoform (SERCA2a) expression using targeted gene therapy may be a potentially powerful new treatment approach for PF. Here, we found that SERCA2a expression was significantly decreased in lung samples from patients with PF and in the bleomycin (BLM) mouse model of PF. In the BLM-induced PF model, intratracheal aerosolized adeno-associated virus serotype 1 (AAV1) encoding for human SERCA2a (AAV1.hSERCA2a) reduces lung fibrosis and associated vascular remodeling. SERCA2a gene therapy also decreases right ventricular pressure and hypertrophy in both prevention and curative protocols. In vitro, we observed that SERCA2a overexpression inhibits fibroblast proliferation, migration, and fibroblast-to-myofibroblast transition induced by transforming growth factor β (TGF-β1). Thus, pro-fibrotic gene expression is prevented by blocking nuclear factor κB (NF-κB)/interleukin-6 (IL-6)-induced signal transducer and activator of transcription 3 (STAT3) activation. This effect is signaled toward an inhibitory mechanism of small mother against decapentaplegic (SMAD)/TGF-β signaling through the repression of OTU deubiquitinase, ubiquitin aldehyde binding 1 (OTUB1) and Forkhead box M1 (FOXM1). Interestingly, this cross-inhibition leads to an increase of SKI and SnoN expression, an auto-inhibitory feedback loop of TGF-β signaling. Collectively, our results demonstrate that SERCA2a gene transfer attenuates bleomycin (BLM)-induced PF by blocking the STAT3/FOXM1 pathway and promoting the SNON/SKI Axis. Thus, SERCA2a gene therapy may be a potential therapeutic target for PF.

Pin1 Plays Essential Roles in NASH Development by Modulating Multiple Target Proteins

Pin1 is one of the three known prolyl-isomerase types and its hepatic expression level is markedly enhanced in the obese state. Pin1 plays critical roles in favoring the exacerbation of both lipid accumulation and fibrotic change accompanying inflammation. Indeed, Pin1-deficient mice are highly resistant to non-alcoholic steatohepatitis (NASH) development by either a high-fat diet or methionine-choline-deficient diet feeding. The processes of NASH development can basically be separated into lipid accumulation and subsequent fibrotic change with inflammation. In this review, we outline the molecular mechanisms by which increased Pin1 promotes both of these phases of NASH. The target proteins of Pin1 involved in lipid accumulation include insulin receptor substrate 1 (IRS-1), AMP-activated protein kinase (AMPK) and acetyl CoA carboxylase 1 (ACC1), while the p60 of the NF-kB complex and transforming growth factor β (TGF-β) pathway appear to be involved in the fibrotic process accelerated by Pin1. Interestingly, Pin1 deficiency does not cause abnormalities in liver size, appearance or function. Therefore, we consider the inhibition of increased Pin1 to be a promising approach to treating NASH and preventing hepatic fibrosis.

Mesoporous Silica Nanoparticles Trigger Liver and Kidney Injury and Fibrosis Via Altering TLR4/NF-κB, JAK2/STAT3 and Nrf2/HO-1 Signaling in Rats

Mesoporous silica nanoparticles (MSNs) represent a promising inorganic platform for multiple biomedical applications. Previous studies have reported MSNs-induced hepatic and renal toxicity; however, the toxic mechanism remains unclear. This study aimed to investigate MSNs-induced hepatic and nephrotoxicity and test the hypothesis that altered TLR4/MyD88/NF-κB, JAK2/STAT3, and Nrf2/ARE/HO-1 signaling pathways mediate oxidative stress, inflammation, and fibrosis induced by MSNs. Rats were administered 25, 50, 100, and 200 mg/kg MSNs for 30 days, and samples were collected for analyses. MSNs induced functional and histologic alterations, increased the levels of reactive oxygen species (ROS), lipid peroxidation and nitric oxide, suppressed antioxidants, and Nrf2/HO-1 signaling in the liver and kidney of rats. MSNs up-regulated the expression of liver and kidney TLR4, MyD88, NF-κB p65, and caspase-3 and increased serum pro-inflammatory cytokines. In addition, MSNs activated the JAK2/STAT3 signaling pathway, down-regulated peroxisome proliferator activated receptor gamma (PPARγ), and promoted fibrosis evidenced by the increased collagen expression and deposition. In conclusion, this study conferred novel information on the role of ROS and deregulated TLR4/MyD88/NF-κB, JAK2/STAT3, PPARγ, and Nrf2/ARE/HO-1 signaling pathways in MSNs hepatic and nephrotoxicity. These findings provide experimental evidence for further studies employing genetic and pharmacological strategies to evaluate the safety of MSNs for their use in nanomedicine.

Macrophages in Systemic Sclerosis: Novel Insights and Therapeutic Implications

PURPOSE OF REVIEW

Macrophages play key roles in tissue homeostasis and immune surveillance, mobilizing immune activation in response to microbial invasion and promoting wound healing to repair damaged tissue. However, failure to resolve macrophage activation can lead to chronic inflammation and fibrosis, and ultimately to pathology. Activated macrophages have been implicated in the pathogenesis of systemic sclerosis (SSc), although the triggers that induce immune activation in SSc and the signaling pathways that underlie aberrant macrophage activation remain unknown.

RECENT FINDINGS

Macrophages are implicated in fibrotic activation in SSc. Targeted therapeutic interventions directed against SSc macrophages may ameliorate inflammation and fibrosis. While current studies have begun to elucidate the role of macrophages in disease initiation and progression, further work is needed to address macrophage subset heterogeneity within and among SSc end-target tissues to determine the disparate functions mediated by these subsets and to identify additional targets for therapeutic intervention.

Aberrant expression of miR-125a-3p promotes fibroblast activation via Fyn/STAT3 pathway during silica-induced pulmonary fibrosis

Various miRNAs are dysregulated during initiation and progression of pulmonary fibrosis. However, their function remains limited in silicosis. Here, we observed that miR-125a-3p was downregulated in silica-induced fibrotic murine lung tissues. Ectopic miR-125a-3p expression with chemotherapy attenuated silica-induced pulmonary fibrosis. Further in vitro experiments revealed that TGF-β1 effectively decreased miR-125a-3p expression in fibroblast lines (NIH/3T3 and MRC-5). Overexpression of miR-125a-3p blocked fibroblast activation stimulated by TGF-β1. Mechanistically, miR-125a-3p could bind to the 3'-untranslated region of Fyn and inhibit its expression in both mRNA and protein levels, thus causing inactivation of Fyn downstream effector STAT3. Fyn and p-STAT3, as opposed to miR-125a-3p expression, were elevated in silica-induced fibrotic murine lung tissues and TGF-β1-treated fibroblast lines. Furthermore, Fyn knockdown or p-STAT3 suppression effectively attenuated fibroblast activation and ECM production. Taken together, miR-125a-3p is involved in fibrosis pathogenesis by fibroblast activation, suggesting that targeting miR-125a-3p/Fyn/STAT3 signaling pathway could be a potential therapeutic approach for pulmonary fibrosis.

Profibrotic effect of IL-17A and elevated IL-17RA in idiopathic pulmonary fibrosis and rheumatoid arthritis-associated lung disease support a direct role for IL-17A/IL-17RA in human fibrotic interstitial lung disease

Interleukin (IL)-17 is a T helper 17 cytokine implicated in the pathogenesis of many autoimmune diseases, including rheumatoid arthritis (RA). Although IL-17A has a well-established role in murine pulmonary fibrosis models, its role in the tissue remodeling and fibrosis occurring in idiopathic pulmonary fibrosis (IPF) and RA-associated interstitial lung disease (RA-ILD) is not very well defined. To address this question, we utilized complimentary studies to determine responsiveness of human normal and pathogenic lung fibroblasts to IL-17A and used lung biopsies acquired from patients with IPF and RA-ILD to determine IL-17A receptor (IL-17RA) expression. Both normal and pathogenic IPF lung fibroblasts express functional IL-17RA and respond to IL-17A stimulation with cell proliferation, generation of extracellular matrix (ECM) proteins, and induction of myofibroblast transdifferentiation. Small interfering RNA (siRNA) silencing of IL-17RA attenuated this fibroblast response to IL-17A on ECM production. These fibroblast responses to IL-17A are dependent on NF-κB-mediated signaling. In addition, inhibiting Janus activated kinase (JAK) 2 by either siRNA or a selective pharmacological inhibitor, AZD1480-but not a JAK1/JAK3 selective inhibitor, tofacitinib-also significantly reduced this IL-17A-induced fibrogenic response. Lung biopsies of RA-ILD patients demonstrate significantly higher IL-17RA expression in areas of fibroblast accumulation and fibrosis, compared with either IPF or normal lung tissue. These observations support a direct role for IL-17A in lung fibrosis that may be particularly relevant in the context of RA-ILD.

Glutamyl-Prolyl-tRNA Synthetase Regulates Epithelial Expression of Mesenchymal Markers and Extracellular Matrix Proteins: Implications for Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF), a chronic disease of unknown cause, is characterized by abnormal accumulation of extracellular matrix (ECM) in fibrotic foci in the lung. Previous studies have shown that the transforming growth factor β1 (TGFβ1) and signal transducers and activators of transcription (STAT) pathways play roles in IPF pathogenesis. Glutamyl-prolyl-tRNA-synthetase (EPRS) has been identified as a target for anti-fibrosis therapy, but the link between EPRS and TGFβ1-mediated IPF pathogenesis remains unknown. Here, we studied the role of EPRS in the development of fibrotic phenotypes in A549 alveolar epithelial cells and bleomycin-treated animal models. We found that EPRS knockdown inhibited the TGFβ1-mediated upregulation of fibronectin and collagen I and the mesenchymal proteins α-smooth muscle actin (α-SMA) and snail 1. TGFβ1-mediated transcription of collagen I-α1 and laminin γ2 in A549 cells was also down-regulated by EPRS suppression, indicating that EPRS is required for ECM protein transcriptions. Activation of STAT signaling in TGFβ1-induced ECM expression was dependent on EPRS. TGFβ1 treatment resulted in EPRS-dependent in vitro formation of a multi-protein complex consisting of the TGFβ1 receptor, EPRS, Janus tyrosine kinases (JAKs), and STATs. In vivo lung tissue from bleomycin-treated mice showed EPRS-dependent STAT6 phosphorylation and ECM production. Our results suggest that epithelial EPRS regulates the expression of mesenchymal markers and ECM proteins via the TGFβ1/STAT signaling pathway. Therefore, epithelial EPRS can be used as a potential target to develop anti-IPF treatments.

Unraveling SSc Pathophysiology; The Myofibroblast

Systemic sclerosis (SSc) is a severe auto-immune disease, characterized by vasculopathy and fibrosis of connective tissues. SSc has a high morbidity and mortality and unfortunately no disease modifying therapy is currently available. A key cell in the pathophysiology of SSc is the myofibroblast. Myofibroblasts are fibroblasts with contractile properties that produce a large amount of pro-fibrotic extracellular matrix molecules such as collagen type I. In this narrative review we will discuss the presence, formation, and role of myofibroblasts in SSc, and how these processes are stimulated and mediated by cells of the (innate) immune system such as mast cells and T helper 2 lymphocytes. Furthermore, current novel therapeutic approaches to target myofibroblasts will be highlighted for future perspective.

Contribution of STAT3 to Inflammatory and Fibrotic Diseases and Prospects for its Targeting for Treatment

Signal transducer and activator of transcription (STAT) 3 plays a central role in the host response to injury. It is activated rapidly within cells by many cytokines, most notably those in the IL-6 family, leading to pro-proliferative and pro-survival programs that assist the host in regaining homeostasis. With persistent activation, however, chronic inflammation and fibrosis ensue, leading to a number of debilitating diseases. This review summarizes advances in our understanding of the role of STAT3 and its targeting in diseases marked by chronic inflammation and/or fibrosis with a focus on those with the largest unmet medical need.

RNAi screening identifies a mechanosensitive ROCK-JAK2-STAT3 network central to myofibroblast activation

Myofibroblasts play key roles in wound healing and pathological fibrosis. Here, we used an RNAi screen to characterize myofibroblast regulatory genes, using a high-content imaging approach to quantify α-smooth muscle actin stress fibers in cultured human fibroblasts. Screen hits were validated on physiological compliance hydrogels, and selected hits tested in primary fibroblasts from patients with idiopathic pulmonary fibrosis. Our RNAi screen led to the identification of STAT3 as an essential mediator of myofibroblast activation and function. Strikingly, we found that STAT3 phosphorylation, while responsive to exogenous ligands on both soft and stiff matrices, is innately active on a stiff matrix in a ligand/receptor-independent, but ROCK- and JAK2-dependent fashion. These results demonstrate how a cytokine-inducible signal can become persistently activated by pathological matrix stiffening. Consistent with a pivotal role for this pathway in driving persistent fibrosis, a STAT3 inhibitor attenuated murine pulmonary fibrosis when administered in a therapeutic fashion after bleomycin injury. Our results identify novel genes essential for the myofibroblast phenotype, and point to STAT3 as an important target in pulmonary fibrosis and other fibrotic diseases.

Fibroblast senescence in the pathology of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic fibrosing interstitial pneumonia of unknown cause with a median survival of only three years. Little is known about the mechanisms that precede the excessive collagen deposition seen in IPF, but cellular senescence has been strongly implicated in disease pathology. Senescence is a state of irreversible cell-cycle arrest accompanied by an abnormal secretory profile and is thought to play a critical role in both development and wound repair. Normally, once a senescent cell has contributed to wound repair, it is promptly removed from the environment via infiltrating immune cells. However, if immune clearance fails, the persistence of senescent cells is thought to drive disease pathology through their altered secretory profile. One of the major cell types involved in wound healing is fibroblasts, and senescent fibroblasts have been identified in the lungs of patients with IPF and in fibroblast cultures from IPF lungs. The question of what is driving abnormally high numbers of fibroblasts into senescence remains unanswered. The transcription factor signal transducer and activator of transcription 3 (STAT3) plays a role in a myriad of processes, including cell-cycle progression, gene transcription, as well as mitochondrial respiration, all of which are dysregulated during senescence. Activation of STAT3 has previously been shown to correlate with IPF progression and therefore is a potential molecular target to modify early-stage senescence and restore normal fibroblast function. This review summarizes what is presently known about fibroblast senescence in IPF and how STAT3 may contribute to this phenotype.