Fibrotic Pathways Research Articles

Recent advances in positron emission tomography for detecting early fibrosis after myocardial infarction

Cardiac remodeling after myocardial infarction is one of the key factors affecting patient prognosis. Myocardial fibrosis is an important pathological link of adverse ventricular remodeling after myocardial infarction, and early fibrosis is reversible. Timely detection and intervention can effectively prevent its progression to irreversible ventricular remodeling. Although imaging modalities such as CMR and echocardiography can identify fibrosis, their sensitivity and specificity are limited, and they cannot detect early fibrosis or its activity level. Positron emission tomography (PET) allows non-invasive visualization of cellular and subcellular processes and can monitor and quantify molecules and proteins in the fibrotic pathway. It is valuable in assessing the extent of early myocardial fibrosis progression, selecting appropriate treatments, evaluating response to therapy, and determining the prognosis. In this article, we present a brief overview of mechanisms underlying myocardial fibrosis following myocardial infarction and several routine imaging techniques currently available for assessing fibrosis. Then, we focus on the application of PET molecular imaging in detecting fibrosis after myocardial infarction.

What Is on the Horizon for Treatments in Idiopathic Pulmonary Fibrosis?

Idiopathic pulmonary fibrosis (IPF) is a progressive and often fatal lung disease most commonly encountered in older individuals. Several decades of research have contributed to a better understanding of its pathogenesis, though only two drugs thus far have shown treatment efficacy, i.e., by slowing the decline of lung function. The pathogenesis of IPF remains incompletely understood and involves multiple complex interactions and mechanisms working in tandem or separately to result in unchecked deposition of extracellular matrix components and collagen characteristic of the disease. These mechanisms include aberrant response to injury in the alveolar epithelium, inappropriate communication between epithelial cells and mesenchymal cells, imbalances between oxidative injury and tissue repair, recruitment of inflammatory pathways that induce fibrosis, and cell senescence leading to sustained activation and proliferation of fibroblasts and myofibroblasts. Targeted approaches to each of these mechanistic pathways have led to recent clinical studies evaluating the safety and efficacy of several agents. This review highlights selected concepts in the pathogenesis of IPF as a rationale for understanding current or future therapeutic approaches, followed by a review of several selected agents and their recent or active clinical studies. Current novel therapies include approaches to attenuating or modifying specific cellular or signaling processes in the fibrotic pathway, modifying inflammatory and metabolic derangements, and minimizing inappropriate cell senescence.

Proliferative Diabetic Retinopathy Microenvironment Drives Microglial Polarization and Promotes Angiogenesis and Fibrosis via Cyclooxygenase-2/Prostaglandin E2 Signaling

Diabetic retinopathy (DR) is the leading cause of visual impairment, particularly in the proliferative form (proliferative DR [PDR]). The impact of the PDR microenvironment on microglia, which are the resident immune cells in the central nervous system, and the specific pathological changes it may induce remain unclear. This study aimed to investigate the role of microglia in the progression of PDR under hypoxic and inflammatory conditions. We performed a comprehensive gene expression analysis using human-induced pluripotent stem cell-derived microglia under different stimuli (dimethyloxalylglycine (DMOG), lipopolysaccharide (LPS), and DMOG + LPS) to mimic the hypoxic inflammatory environment characteristic of PDR. Principal component analysis revealed distinct gene expression profiles, with 76 genes synergistically upregulated under combined stimulation. Notably, prostaglandin-endoperoxide synthase 2 (encoding cyclooxygenase (COX)-2) exhibited the most pronounced increase, leading to elevated prostaglandin E2 (PGE2) levels and driving pathological angiogenesis and inflammation via the COX-2/PGE2/PGE receptor 2 signaling axis. Additionally, the upregulation of the fibrogenic genes snail family transcriptional repressor 1 and collagen type I alpha 1 chain suggested a role for microglia in fibrosis. These findings underscore the critical involvement of microglia in PDR and suggest that targeting both the angiogenic and fibrotic pathways may present new therapeutic strategies for managing this condition.

Effects of Cannabidiol on Intestinal Myofibroblast Fibrotic PathwaysPATHWAYS

Inflammatory bowel disease (IBD) includes two immune-mediated disorders, Crohn’s disease (CD) and ulcerative colitis (UC). IBD is characterized by recurrent and chronic inflammation of the gastrointestinal tract. IBD is lifelong, and there is no cure. There has been an interest in new advanced medications to decrease inflammation and manage symptoms. Many of these new medications are expensive and depress the immune system, leaving many patients looking for alternatives to current medical therapies. Some IBD patients use medical marijuana to relieve the symptoms of this disease, and cannabidiol (CBD) in particular shows potential for reducing inflammation. This study investigates the potential therapeutic effects of CBD on IBD by examining its impact on fibrotic pathways in human intestinal myofibroblast (InMyoFib) cells. Cultured InMyoFibs were pre-treated with CBD, followed by transforming growth factor-beta 1 (TGF-β1) to stimulate a pro-fibrotic phenotype and mimic human IBD in the lab. Expression of genes associated with fibrosis, inflammation, and cannabinoid signaling was measured by quantitative polymerase chain reaction (qPCR). Fibrotic protein expression in the culture media was analyzed using enzyme-linked immunosorbent assays (ELISA). CBD pre-treatment before TGF-β1 stimulation significantly reduced the expression of pro-fibrotic genes ACTA2, CCN2, COL1A1, and SERPINH1 compared to cells stimulated with TGF-β1 alone. Additionally, CBD increased the expression of inflammation-related genes IL6 and PTGS2 and the lipid metabolism gene PPARG, known to have anti-fibrotic properties. These findings suggest that CBD may modulate fibrotic and inflammatory signaling pathways, providing a potential therapeutic avenue for IBD treatment.

Proliferative Vitreoretinopathy in Retinal Detachment: Perspectives on Building a Digital Twin Model Using Nintedanib.

Proliferative vitreoretinopathy (PVR) is a pathological process characterized by the formation of fibrotic membranes that contract and lead to recurrent retinal detachment. Pars plana vitrectomy (PPV) is the primary treatment, but recurrence rates remain high, as surgery does not address the underlying molecular mechanisms driving fibrosis. Despite several proposed pharmacological interventions, no approved therapies exist, partly due to challenges in conducting preclinical and in vivo studies for ethical and safety reasons. This review explores the potential of computational models and Digital Twins, which are increasingly gaining attention in medicine. These tools could enable the development of progressively complex PVR models, from basic simulations to patient-specific Digital Twins. Nintedanib, a tyrosine kinase inhibitor targeting PDGFR, VEGFR, and FGFR, is presented as a prototype for computational models to simulate its effects on fibrotic pathways in virtual patient cohorts. Although still in its early stages, the integration of computational models and Digital Twins offers promising avenues for improving PVR management through more personalized therapeutic strategies.

Emerging Roles of Ketone Bodies in Cardiac Fibrosis.

Cardiac fibrosis, characterized by excessive extracellular matrix (ECM) deposition within the myocardium, poses a significant challenge in cardiovascular health, contributing to various cardiac pathologies. Ketone bodies (KBs), particularly β-hydroxybutyrate (β-OHB), have emerged as subjects of interest due to their potential cardioprotective effects. However, their specific influence on cardiac fibrosis remains underexplored. This literature review comprehensively examines the relationship between KBs and cardiac fibrosis, elucidating potential mechanisms through which KBs modulate fibrotic pathways. A multifaceted interplay exists between KBs and key mediators of cardiac fibrosis. While some studies indicate a pro-fibrotic role for KBs, others highlight their potential to attenuate fibrosis and cardiac remodeling. Mechanistically, KBs may regulate fibrotic pathways through modulation of cellular components such as cardiac fibroblasts, macrophages, and lymphocytes, as well as extracellular matrix proteins. Furthermore, the impact of KBs on cellular processes implicated in fibrosis, including oxidative stress, chemokine and cytokine expression, caspase activation, and inflammasome signaling are explored. While conflicting findings exist regarding the effects of KBs on these processes, emerging evidence suggests a predominantly beneficial role in mitigating inflammation and oxidative stress associated with fibrotic remodeling. Overall, this review underscores the importance of elucidating the complex interplay between KB metabolism and cardiac fibrosis. Insights gained have the potential to inform novel therapeutic strategies for managing cardiac fibrosis and associated cardiovascular disorders, highlighting the need for further research in this area.

Preparing the soil: Adjusting the metabolic health of patients with chronic wounds and musculoskeletal diseases.

In recent years, systemic inflammation has emerged as a pivotal player in the development and progression of various degenerative diseases. This complex, chronic inflammatory state, often undetected, can have far-reaching consequences for the body's physiology. At the molecular level, markers such as C-reactive protein, cytokines and other inflammatory mediators serve as indicators of systemic inflammation and often act as predictors of numerous musculoskeletal diseases and even certain forms of cancer. The concept of 'meta-inflammation', specifically referring to metabolically triggered inflammation, allows healthcare professionals to understand inflammatory responses in patients with metabolic syndrome. Driven by nutrient excess and the expansion of adipose tissue, meta-inflammation is closely associated with insulin resistance, further propagating the metabolic dysfunction observed in many Western societies. Wound persistence, on the other hand, exacerbates the detrimental effects of prolonged inflammation at the local level. Acute inflammation is a beneficial and essential process for wound healing and infection control. However, when inflammation fails to resolve, it can impede the healing process, leading to chronic wounds, excessive scarring and even the activation of fibrotic pathways. This approach significantly reduces the efficacy of regenerative biological therapies. Our review focuses on the vital role of proteins, vitamins and minerals in collagen synthesis and cell proliferation for tissue healing. We also examine hormonal influences on regeneration, noting the negative effects of imbalances, and emphasize glucose regulation's importance in creating a stable environment for chronic wound healing.

TLR-2 and TLR-4 mRNA expression in different grades of histopathological lesions of equine endometrium from follicular phase.

Increased synthesis and deposition of collagen(COL) in the extracellular matrix (ECM) of equine endometrium contributes to endometrosis. Toll-like receptors (TLRs) are transmembrane receptors involved in the innate immune response, recognized for their role in antigen recognition and previously associated with equine endometritis. The TLRs not only recognize pathogen-associated molecular patterns but also regulate inflammations, fibrosis and cancer. The aim of this study was to explore the relationship between TLR expression at different stages of Kenney and Doig's (K-D) grading and COL1 expression during the follicular phase of the oestrous cycle. Forty samples of endometrial tissues were collected post-mortem from mares on the follicular phase of the oestrous cycle (10 samples of each K-D category). Relative mRNA transcription of TLR-2, TLR-4 and COL1A2 genes was assessed using qPCR, and COL1 protein expression by Western blot analysis. The COL1A2 transcription increased in category IIB when compared to categories I, IIA and III endometria (p < .01). The relative protein abundance of COL1 showed no significant differences between endometrial categories (p > .05). As for the TLRs mRNA transcription, TLR-2/-4 transcripts increased in IIA when compared to the other K-D endometria categories (p < .05). Our findings suggest that TLRs may be involved in the initiation of the endometrial inflammatory response. Additional studies are needed to explore TLRs' potential role as diagnostic markers for monitoring inflammation progression and fibrosis development, as well as their involvement in the mechanisms underlying fibrotic pathways.

TongGuanWan Alleviates Doxorubicin- and Isoproterenol-Induced Cardiac Hypertrophy and Fibrosis by Modulating Apoptotic and Fibrotic Pathways.

Heart failure, a major public health issue, often stems from prolonged stress or damage to the heart muscle, leading to cardiac hypertrophy. This can progress to heart failure and other cardiovascular problems. Doxorubicin (DOX), a common chemotherapy drug, and isoproterenol (ISO), a β-adrenergic agonist, both induce cardiac hypertrophy through different mechanisms. This study investigates TongGuanWan (TGW,), a traditional herbal remedy, for its effects on cardiac hypertrophy and fibrosis in DOX-induced H9c2 cells and ISO-induced mouse models. TGW was found to counteract DOX-induced increases in H9c2 cell surface area (n = 8, p < 0.01) and improve biomarkers like ANP (n = 3, p < 0.01)) and BNP (n = 3, p < 0.01). It inhibited the MAPK pathway (n = 4, p < 0.01) and GATA-4/calcineurin/NFAT-3 signaling, reduced inflammation by decreasing NF-κB p65 translocation, and enhanced apoptosis-related factors such as caspase-3 (n = 3, p < 0.01), caspase-9 (n = 3, p < 0.01), Bax (n = 3, p < 0.01), and Bcl-2 (n = 3, p < 0.01). Flow cytometry showed TGW reduced apoptotic cell populations. In vivo, TGW reduced heart (n = 8~10, p < 0.01), and left ventricle weights (n = 6~7), cardiac hypertrophy markers (n = 3, p < 0.01), and perivascular fibrosis in ISO-induced mice, with Western blot analysis confirming decreased levels of fibrosis-related factors like fibronectin, α-SMA (n = 3, p < 0.05), and collagen type I (n = 3, p < 0.05). These findings suggest TGW has potential as a therapeutic option for cardiac hypertrophy and fibrosis.

Chronic sleep deprivation induces erectile dysfunction through increased oxidative stress, apoptosis, endothelial dysfunction, and corporal fibrosis in a rat model.

Sleep is foundational for nocturnal erections, facilitating nutrient exchange and waste removal, which has brought widespread attention to the relationship between sleep and erectile dysfunction (ED). However, there is currently a lack of basic research confirming whether chronic sleep deprivation (CSD) leads to erectile impairment and its underlying pathological mechanisms. The study sought to investigate whether CSD impairs erectile function in rats and the potential tissue damage it may cause in rats. The modified multiple platform method was employed to induce CSD in 14 rats, randomly divided into a platform control group and a CSD group. After 3 weeks, erectile function was evaluated by measuring intracavernosal pressure following cavernous nerve stimulation. Arterial blood samples were then analyzed for testosterone levels, and cavernous tissues were processed for advanced molecular biology assays, including Western blotting and immunofluorescence. After inducing CSD, rats exhibited a marked reduction in erectile function, yet their serum testosterone levels remained statistically unchanged when compared with the control group. More importantly, rats in the CSD group exhibited a significant increase in oxidative stress levels, accompanied by low expression of HO-1 and high expression of NOX1 and NOX4. Subsequently, elevated oxidative stress induced increased apoptosis in smooth muscle and endothelial cells, as evidenced by significant decreases in CD31 and α-smooth muscle actin expression in the CSD group, demonstrated through Western blotting and immunofluorescence assays. Endothelial cell apoptosis led to a significant decrease in endothelial nitric oxide synthase, resulting in lowered levels of nitric oxide and cyclic guanosine monophosphate, which severely impaired the erectile mechanism. Additionally, activation of the transforming growth factor β1 fibrotic pathway led to increased levels of tissue fibrosis, resulting in irreversible damage to the penile tissue in the CSD group. Our study lacks further exploration of the molecular mechanisms linking CSD and ED, representing a future research focus for potential targeted therapies. Our findings demonstrated that CSD significantly impairs erectile function in rats. CSD severely impairs erectile function in rats. When exposed to CSD, rats exhibit significantly elevated oxidative stress levels, which lead to increased tissue apoptosis, endothelial dysfunction, and ultimately irreversible fibrotic changes in the tissues. Further researches into the potential molecular mechanisms are needed to identify possible therapeutic targets for ED related to CSD.

Dysregulation of sphingolipid metabolism in liver fibrosis

The dysregulation of sphingolipid metabolism emerges as a pivotal factor in the development and progression of liver fibrosis, a condition marked by the overproduction and buildup of extracellular matrix proteins that can lead to liver cirrhosis and failure. Sphingolipids, a diverse class of lipids essential for cellular structure and signaling, are integral to numerous biological functions such as cellular proliferation, morphological differentiation, and programmed cell death. In the context of liver fibrosis, changes in sphingolipid metabolism have been associated with the activation of hepatic stellate cells, the primary cells responsible for fibrogenesis in the liver. These metabolic disruptions lead to an imbalance between profibrotic and antifibrotic sphingolipids, notably sphingosine-1-phosphate and ceramide, contributing to the pathophysiological mechanisms that drive fibrosis. The intricate relationship between sphingolipid metabolism and fibrotic pathways underscores the potential of targeting sphingolipid metabolic enzymes and receptors as therapeutic strategies to mitigate liver fibrosis. The core of this review delves into how disruptions in sphingolipid metabolism contribute to liver fibrosis, exploring biomarkers and potential therapeutic targets. Challenges in research and future directions for comprehensively understanding sphingolipid roles in liver fibrosis are discussed, aiming to open new pathways for therapeutic intervention.

Aberrant activation of wound healing programs within the metastatic niche facilitates lung colonization by osteosarcoma cells.

Lung metastasis is responsible for nearly all deaths caused by osteosarcoma, the most common pediatric bone tumor. How malignant bone cells coerce the lung microenvironment to support metastatic growth is unclear. The purpose of this study is to identify metastasis-specific therapeutic vulnerabilities by delineating the cellular and molecular mechanisms underlying osteosarcoma lung metastatic niche formation. Using single-cell transcriptomics (scRNA-seq), we characterized genome- and tissue-wide molecular changes induced within lung tissues by disseminated osteosarcoma cells in both immunocompetent murine models of metastasis and patient samples. We confirmed transcriptomic findings at the protein level and determined spatial relationships with multi-parameter immunofluorescence and spatial transcriptomics. Based on these findings, we evaluated the ability of nintedanib, a kinase inhibitor used to treat patients with pulmonary fibrosis, to impair metastasis progression in both immunocompetent murine osteosarcoma and immunodeficient human xenograft models. Single-nucleus and spatial transcriptomics was used to perform molecular pharmacodynamic studies that define the effects of nintedanib on tumor and non-tumor cells within the metastatic microenvironment. Osteosarcoma cells induced acute alveolar epithelial injury upon lung dissemination. scRNA-seq demonstrated that the surrounding lung stroma adopts a chronic, non-resolving wound-healing phenotype similar to that seen in other models of lung injury. Accordingly, metastasis-associated lung demonstrated marked fibrosis, likely due to the accumulation of pathogenic, pro-fibrotic, partially differentiated epithelial intermediates and macrophages. Our data demonstrated that nintedanib prevented metastatic progression in multiple murine and human xenograft models by inhibiting osteosarcoma-induced fibrosis. Fibrosis represents a targetable vulnerability to block the progression of osteosarcoma lung metastasis. Our data support a model wherein interactions between osteosarcoma cells and epithelial cells create a pro-metastatic niche by inducing tumor deposition of extracellular matrix proteins such as fibronectin that is disrupted by the anti-fibrotic TKI nintedanib. Our data shed light on the non-cell autonomous effects of TKIs on metastasis and provide a roadmap for using single-cell and spatial transcriptomics to define the mechanism of action of TKI on metastases in animal models.

Vitamin B1 and calcitriol enhance glibenclamide suppression of diabetic nephropathy: Role of HMGB1/TLR4/NF-κB/TNF-α/Nrf2/α-SMA trajectories

Glibenclamide is one of the most prescribed insulin secretagogues in diabetes due to its low cost, but its efficacy on suppressing diabetic complications is limited. Here, we examine whether addition of either vitamin B1 or calcitriol to glibenclamide could produce more suppression of diabetic nephropathy. Type 2 diabetes was induced by high fructose (10 % in drinking water), high salt (3 % in diet), and high fat diet (25 % in diet) for 3 weeks, followed by single dose of STZ (40 mg/kg, i.p.). Diabetic rats were treated with either glibenclamide (0.6 mg/kg), vitamin B1 (70 mg/kg), glibenclamide/vitamin B1, calcitriol (0.1 μg/kg), or glibenclamide/calcitriol. Addition of either vitamin B1 or calcitriol to glibenclamide therapy enabled more suppression of diabetic nephropathy development as evidenced by more preserved creatinine clearance and less renal damage scores. Combination therapy resulted in mild enhancement in the effect of glibenclamide on glucose tolerance without affecting the area under the curve. Combination therapy was associated with more suppression of inflammatory cascades as evidenced by reducing the expression of high mobility group box-1 (HMGB1), toll-like receptor-4 (TLR4), nuclear factor-kappa B (NF-κB), and tumor necrosis factor-α (TNF-α). In addition, combination therapy enhanced the antioxidant mechanisms as evidenced by increased expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and glutathione content and reducing malondialdehyde and nitric oxide levels. Furthermore, combination therapy provided more suppression of fibrotic pathways as appear from reducing collagen deposition and the expression of α- smooth muscle actin (α-SMA). In conclusion, addition of vitamin B1 or calcitriol to glibenclamide therapy can enhance the therapeutic efficiency of glibenclamide in suppressing diabetic nephropathy progression to the same extend, the protective effect is mediated through modulating HMGB1/TLR4/NF-κB/TNF-α/Nrf2/α-SMA trajectories.

Ccn2 Deletion Reduces Cardiac Dysfunction, Oxidative Markers, and Fibrosis Induced by Doxorubicin Administration in Mice.

Cellular Communication Network Factor 2 (CCN2) is a matricellular protein implicated in cell communication and microenvironmental signaling. Overexpression of CCN2 has been documented in various cardiovascular pathologies, wherein it may exert either deleterious or protective effects depending on the pathological context, thereby suggesting that its role in the cardiovascular system is not yet fully elucidated. In this study, we aimed to investigate the effects of Ccn2 gene deletion on the progression of acute cardiac injury induced by doxorubicin (DOX), a widely utilized chemotherapeutic agent. To this end, we employed conditional knockout (KO) mice for the Ccn2 gene (CCN2-KO), which were administered DOX and compared to DOX-treated wild-type (WT) control mice. Our findings demonstrated that the ablation of CCN2 ameliorated DOX-induced cardiac dysfunction, as evidenced by improvements in ejection fraction (EF) and fractional shortening (FS) of the left ventricle. Furthermore, DOX-treated CCN2-KO mice exhibited a significant reduction in the gene expression and activation of oxidative stress markers (Hmox1 and Nfe2l2/NRF2) relative to DOX-treated WT controls. Additionally, the deletion of Ccn2 markedly attenuated DOX-induced cardiac fibrosis. Collectively, these results suggest that CCN2 plays a pivotal role in the pathogenesis of DOX-mediated cardiotoxicity by modulating oxidative stress and fibrotic pathways. These findings provide a novel avenue for future investigations to explore the therapeutic potential of targeting CCN2 in the prevention of DOX-induced cardiac dysfunction.

Potential of phosphodiesterase 4B inhibitors in the treatment of interstitial lung disease associated with autoimmune diseases.

Patients with autoimmune disease-related interstitial lung disease may develop pulmonary fibrosis, which may become progressive. Progressive pulmonary fibrosis (PPF) is associated with poor outcomes. Antifibrotic therapies have shown efficacy as treatments for PPF in patients with autoimmune diseases, but new treatments are needed to slow or halt disease progression. Phosphodiesterases (PDEs) are enzymes that mediate the hydrolysis of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Pre-clinical data suggest that preferential inhibition of PDE4B has the potential to slow the progression of pulmonary fibrosis by inhibiting inflammatory and fibrotic pathways, with a lower risk of gastrointestinal adverse events than associated with pan-PDE4 inhibitors. Nerandomilast (BI 1015550) is a preferential PDE4 inhibitor that has demonstrated anti-inflammatory and antifibrotic effects in pre-clinical studies. In a phase II trial in patients with idiopathic pulmonary fibrosis, nerandomilast (given alone or on top of background antifibrotic therapy) prevented a decrease in lung function over 12 weeks with an acceptable safety and tolerability profile. The phase III FIBRONEER-ILD trial is evaluating the efficacy and safety of nerandomilast, given alone or on top of nintedanib, in patients with PPF, including PPF associated with autoimmune diseases. In this article, we review the potential of PDE4B inhibition in the treatment of ILD associated with autoimmune diseases, including the pre-clinical and early clinical data available to date.

Gene Expression Sets and Renal Profiling from the Renal AL Amyloid Involvement and NEOD00 (RAIN) Trial

There is an unmet need to understand the mechanisms by which amyloid deposition drives alterations in the kidney. We leveraged renal biopsies from amyloid light-chain (AL) amyloidosis participants of the Renal AL Amyloid Involvement and NEOD00 (RAIN) trial (NCT03168906) to perform transcriptional profiling and to employ a novel histologic scoring tool. Our objective was to utilize a transcriptome-driven approach to identify AL molecular signatures that may be prognostic. Clinical data were correlated to histologic and molecular findings. A composite scarring injury and amyloid score (AS) were assigned to each biopsy. Glomerular and tubulointerstitial (TI) compartments were microdissected and sequenced separately. Expression data were compared to healthy living donors and focal segmental glomerulosclerosis (FSGS) profiles. Differentially expressed genes were determined. Cluster analysis revealed 2 distinct patient clusters (G1 and G2) based on gene expression. The AS was higher in the TI compartment (6.5 vs. 4.5; P= 0.0290) of G2. Glomeruli showed activation of fibrotic pathways and increased canonical signaling of LPS/IL-1. TNF activation was noted in TI. Enriched ingenuity canonical pathways included "coagulation system," "GADD45 signaling," and "Wnt/Ca+ pathway," among others. For AL versus living donors, ingenuity pathway analysis identified enrichment in PI3K/Akt signaling. Gene regulators of cellular proliferation were enriched in the amyloid group. Despite the small sample size, we identified 2 distinct groups of patients with AL based on molecular signatures. Detailed studies of a larger cohort encompassing omics technologies at a single cell resolution will further help to identify the response of individual kidney cell types to amyloid deposits, potentially leading to the development of novel therapeutic targets.

Distinct phenotypes induced by acute hypoxia and TGF-β1 in human adult cardiac fibroblasts

Myocardial infarction (MI) causes hypoxic injury to downstream myocardial tissue, which initiates a wound healing response that replaces injured myocardial tissue with a scar. Wound healing is a complex process that consists of multiple phases, in which many different stimuli induce cardiac fibroblasts to differentiate into myofibroblasts and deposit new matrix. While this process is necessary to replace necrotic tissue, excessive and unresolved fibrosis is common post-MI and correlated with heart failure. Therefore, defining how cardiac fibroblast phenotypes are distinctly regulated by stimuli that are prevalent in the post-MI microenvironment, such as hypoxia and transforming growth factor-beta (TGF-β), is essential for understanding and ultimately mitigating pathological fibrosis. In this study, we acutely treated primary human adult cardiac fibroblasts with TGF-β1 or hypoxia and then characterized their phenotype through immunofluorescence, quantitative RT-PCR, and proteomic analysis. We found that fibroblasts responded to low oxygen with increased localization of hypoxia inducible factor 1 (HIF-1) to the nuclei after 4 h, which was followed by increased gene expression of vascular endothelial growth factor A (VEGFA), a known target of HIF-1, by 24 h. Both TGF-β1 and hypoxia inhibited proliferation after 24 h. TGF-β1 treatment also upregulated various fibrotic pathways. In contrast, hypoxia caused a reduction in several protein synthesis pathways, including collagen biosynthesis. Collectively, these data suggest that TGF-β1, but not acute hypoxia, robustly induces the differentiation of human cardiac fibroblasts into myofibroblasts. Discerning the overlapping and distinctive outcomes of TGF-β1 and hypoxia treatment is important for elucidating their roles in fibrotic remodeling post-MI and provides insight into potential therapeutic targets.

Exosomal miR-17-5p derived from epithelial cells is involved in aberrant epithelium-fibroblast crosstalk and induces the development of oral submucosal fibrosis

Oral submucous fibrosis (OSF) is a chronic and inflammatory mucosal disease caused by betel quid chewing, which belongs to oral potentially malignant disorders. Abnormal fibroblast differentiation leading to disordered collagen metabolism is the core process underlying OSF development. The epithelium, which is the first line of defense against the external environment, can convert external signals into pathological signals and participate in the remodeling of the fibrotic microenvironment. However, the specific mechanisms by which the epithelium drives fibroblast differentiation remain unclear. In this study, we found that Arecoline-exposed epithelium communicated with the fibrotic microenvironment by secreting exosomes. MiR-17-5p was encapsulated in epithelial cell-derived exosomes and absorbed by fibroblasts, where it promoted cell secretion, contraction, migration and fibrogenic marker (α-SMA and collagen type I) expression. The underlying molecular mechanism involved miR-17-5p targeting Smad7 and suppressing the degradation of TGF-β receptor 1 (TGFBR1) through the E3 ubiquitination ligase WWP1, thus facilitating downstream TGF-β pathway signaling. Treatment of fibroblasts with an inhibitor of miR-17-5p reversed the contraction and migration phenotypes induced by epithelial-derived exosomes. Exosomal miR-17-5p was confirmed to function as a key regulator of the phenotypic transformation of fibroblasts. In conclusion, we demonstrated that Arecoline triggers aberrant epithelium-fibroblast crosstalk and identified that epithelial cell-derived miR-17-5p mediates fibroblast differentiation through the classical TGF-β fibrotic pathway, which provided a new perspective and strategy for the diagnosis and treatment of OSF.

Epithelium-derived exosomes promote silica nanoparticles-induced pulmonary fibroblast activation and collagen deposition via modulating fibrotic signaling pathways and their epigenetic regulations

BackgroundIn the context of increasing exposure to silica nanoparticles (SiNPs) and ensuing respiratory health risks, emerging evidence has suggested that SiNPs can cause a series of pathological lung injuries, including fibrotic lesions. However, the underlying mediators in the lung fibrogenesis caused by SiNPs have not yet been elucidated.ResultsThe in vivo investigation verified that long-term inhalation exposure to SiNPs induced fibroblast activation and collagen deposition in the rat lungs. In vitro, the uptake of exosomes derived from SiNPs-stimulated lung epithelial cells (BEAS-2B) by fibroblasts (MRC-5) enhanced its proliferation, adhesion, and activation. In particular, the mechanistic investigation revealed SiNPs stimulated an increase of epithelium-secreted exosomal miR-494-3p and thereby disrupted the TGF-β/BMPR2/Smad pathway in fibroblasts via targeting bone morphogenetic protein receptor 2 (BMPR2), ultimately resulting in fibroblast activation and collagen deposition. Conversely, the inhibitor of exosomes, GW4869, can abolish the induction of upregulated miR-494-3p and fibroblast activation in MRC-5 cells by the SiNPs-treated supernatants of BEAS-2B. Besides, inhibiting miR-494-3p or overexpression of BMPR2 could ameliorate fibroblast activation by interfering with the TGF-β/BMPR2/Smad pathway.ConclusionsOur data suggested pulmonary epithelium-derived exosomes serve an essential role in fibroblast activation and collagen deposition in the lungs upon SiNPs stimuli, in particular, attributing to exosomal miR-494-3p targeting BMPR2 to modulate TGF-β/BMPR2/Smad pathway. Hence, strategies targeting exosomes could be a new avenue in developing therapeutics against lung injury elicited by SiNPs.Graphical

Fibrotic pathways and fibroblast-like synoviocyte phenotypes in osteoarthritis.

Osteoarthritis (OA) is the most common form of arthritis, characterized by osteophyte formation, cartilage degradation, and structural and cellular alterations of the synovial membrane. Activated fibroblast-like synoviocytes (FLS) of the synovial membrane have been identified as key drivers, secreting humoral mediators that maintain inflammatory processes, proteases that cause cartilage and bone destruction, and factors that drive fibrotic processes. In normal tissue repair, fibrotic processes are terminated after the damage has been repaired. In fibrosis, tissue remodeling and wound healing are exaggerated and prolonged. Various stressors, including aging, joint instability, and inflammation, lead to structural damage of the joint and micro lesions within the synovial tissue. One result is the reduced production of synovial fluid (lubricants), which reduces the lubricity of the cartilage areas, leading to cartilage damage. In the synovial tissue, a wound-healing cascade is initiated by activating macrophages, Th2 cells, and FLS. The latter can be divided into two major populations. The destructive thymocyte differentiation antigen (THY)1─ phenotype is restricted to the synovial lining layer. In contrast, the THY1+ phenotype of the sublining layer is classified as an invasive one with immune effector function driving synovitis. The exact mechanisms involved in the transition of fibroblasts into a myofibroblast-like phenotype that drives fibrosis remain unclear. The review provides an overview of the phenotypes and spatial distribution of FLS in the synovial membrane of OA, describes the mechanisms of fibroblast into myofibroblast activation, and the metabolic alterations of myofibroblast-like cells.