Role of macrophages in peritoneal dialysis-associated peritoneal fibrosis

Peritoneal dialysis (PD) can be used as renal replacement therapy when chronic kidney disease (CKD) progresses to end-stage renal disease. However, peritoneal fibrosis (PF) is a major cause of PD failure. Studies have demonstrated that PD fluid contains a significantly larger numbers of macrophages compared with the healthy individuals. During PD, macrophages can secrete cytokines to keep peritoneal tissue in sustained low-grade inflammation, and participate in the regulation of fibrosis-related signaling pathways, such as NF-κB, TGF-β/Smad, IL4/STAT6, and PI3K/AKT. A series of basic pathological changes occurs in peritoneal tissues, including epithelial mesenchymal transformation, overgeneration of neovasculature, and abnormal deposition of extracellular matrix. This review focuses on the role of macrophages in promoting PF during PD, summarizes the targets of macrophage-related inhibition of fibrosis, and provides new ideas for clinical research on delaying PF, maintaining the function and integrity of peritoneum, prolonging duration of PD as a renal replacement modality, and achieving longer survival in CKD patients.

Mechanical stress overload promotes NF-κB/NLRP3-mediated osteoarthritis synovitis and fibrosis through Piezo1

Mechanical stress is a pivotal factor in the development of knee osteoarthritis (KOA). Piezo1, an innovative mechanosensitive ion channel, plays a key role in detecting variations in mechanical stress and transforming them into electrical signals. This research focuses on examining how Piezo1 influences synovial inflammation and fibrosis induced by mechanical stress in KOA, as well as delving into the potential underlying mechanisms. In vivo, pathological changes and immunohistochemical staining were conducted on both normal and overexercise rat synovial tissues to analyze the expression of Piezo1 and the NF-κB/NLRP3 pathways. In vitro utilized a cell stretcher to replicate the mechanical conditions seen in KOA. Levels of pro-inflammatory cytokines and fibrosis-related markers were assessed to investigate the impact of Piezo1 on mechanical stress in fibroblast-like synoviocytes (FLS). Subsequently, following cell stretching interventions, the effects on synovial inflammation and fibrosis were observed with the use of the Piezo1 inhibitor GsMTx4 or the NLRP3 inhibitor MCC950. Mechanical stress significantly promoted the activation of Piezo1, increased the phosphorylation ratio of p65, and elevated the levels of NLRP3, caspase-1, ASC, GSDMD, IL-1β, IL-18, IL-6, and TNF-α. Both in vitro and in vivo, mechanical stress also promoted the occurrence and development of synovial fibrosis, with significant increases in the expression levels of fibrosis-related markers. Under mechanical stress overload, upregulation of Piezo1 can promote the secretion of pro-inflammatory cytokines and the fibrotic process in synovium through the NF-κB/NLRP3 signaling pathway.

Circadian clock regulation of myofibroblast fate

Fibrosis-related disorders represent an increasing medical and economic burden on a worldwide scale, accounting for one-third of all disease-related deaths with limited therapeutic options. As central mediators in fibrosis development, myofibroblasts have been gaining increasing attention in the last 20 years as potential targets for fibrosis attenuation and reversal. While various aspects of myofibroblast physiology have been proposed as treatment targets, many of these approaches have shown limited long-term efficacy so far. However, ongoing research is uncovering new potential strategies for targeting myofibroblast activity, offering hope for more effective treatments in the future. The circadian molecular clock is a feature of almost every cell in the human body that dictates the rhythmic nature of various aspects of human physiology and behavior in response to changes in the surrounding environment. The dysregulation of these rhythms with aging is considered to be one of the underlying reasons behind the development of multiple aging-related chronic disorders, with fibrotic tissue scarring being a common pathological complication among the majority of them. Myofibroblast dysregulation due to skewed circadian clockwork might significantly contribute to fibrotic scar persistence. In the current review, we highlight the role of the circadian clock in the context of myofibroblast activation and deactivation and examine its dysregulation as a driver of fibrogenesis.

Near-infrared light triggered bio-inspired enhanced natural silk fibroin nanofiber composite scaffold for photothermal therapy of periodontitis

Periodontitis is one of the major oral health issues worldwide, with significant impacts on oral health and patients's quality of life, but current therapies have not achieved optimal regeneration of periodontal tissue. This study developed scaffolds using natural tussah silk fibroin (TSF) cross-linked with regenerated silk fibroin (SF) nanofibers to improve mechanical properties and wet-state stability. Zinc oxide (ZnO) and polydopamine (PDA) composite nanoparticles were loaded into scaffold to impart its antibacterial and photothermal properties to construct a photo-responsive composite scaffold (ZnO/PDA/TSF-SF). After characterization, ZnO/PDA/TSF-SF demonstrated excellent antibacterial ability, biocompatibility, and photothermal stability. In vitro cell evaluations under 635 nm red light irradiation-mediated photo-biomodulation (PBM) demonstrated that ZnO/PDA/TSF-SF promoted fibroblast proliferation and enhanced expression of proteins and genes associated with tissue repair, such as collagen I (Col I), fibronectin (FN), and alpha smooth muscle actin (α-SMA). A rat model of periodontitis developed for evaluations of antibacterial and tissue repair effects showed that ZnO/PDA/TSF-SF improved alveolar bone and reversed bone loss. ZnO/PDA/TSF-SF improved inflammation significantly through reduction in tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), and IL-6 levels in serum and gingival tissues of modeled rats. Also, the scaffold markedly increased levels of anti-inflammatory cytokine interleukin-10 (IL-10) and elevated protein and mRNA expression levels of tissue repair-related proteins and endothelial cell markers. ZnO/PDA/TSF-SF scaffold exhibited good biocompatibility, osteogenesis, and photo-responsive antibacterial properties, thereby demonstrating therapeutic potential in treating periodontitis.

Substrate stiffness modifies gene expression and transcriptional response of equine endometrial fibroblasts to TGF-β1

Equine endometrial fibrosis is a leading cause of subfertility in aging mares. Fibrosis is a reparative response involving excess deposition of extracellular matrix (ECM) and increasing tissue stiffness. Augmented rigidity itself can drive fibrosis, by stimulating transition from fibroblasts to myofibroblasts. Myofibroblasts release latent transforming growth factor beta 1 (TGF-β1) from the ECM, thereby activating this profibrotic cytokine. Tissue culture polystyrene (TCP) is commonly used for in vitro experiments. The endometrium, however, is considerably softer than TCP. This study critically evaluated the use of hydrogels versus TCP. Differences in transcript abundance between equine endometrial fibroblasts cultured on TCP and hydrogels of decreasing stiffness (25 kPa to 2 kPa) and their transcriptional response to TGF-β1, were examined. Cells cultured on substrates of varying stiffness exhibited visual variations concerning adherence, morphology, and cell density, besides differences in basal gene expression and transcriptional response to TGF-β1. On stiffer substrates, the smooth muscle genes TAGLN and ACTA2, alongside the transcripts encoding the signaling proteins PDGFB, CCN2, and SERPINE1 were expressed at higher levels. This pattern was also evident for integrin receptor subunit ITGAV, while ITGB5 was expressed at lower levels on stiffer substrates. While ITGB3 demonstrated a response to TGF-β1 exposure independent of stiffness, an increase in transcript abundance of PDGFB, ITGAV, and ITGB5 towards TGF-β1 was only observed on softer hydrogels. The results highlight the importance of stiffness in cellular regulatory patterns, particularly relevant to fibrosis research. We recommend critically reconsidering the use of TCP when designing experiments in vitro.

Marrow adipogenic lineage precursors (MALPs) facilitate bone marrow recovery after chemotherapy

Chemotherapy-induced hematopoietic toxicity is a multifactorial challenge in the treatment of oncology patients. The resultant bone marrow suppression is a major dose-limiting side effect. In this study, we utilized 5-fluorouracil (5-FU), a commonly used chemotherapeutic agent, to investigate the mechanisms underlying bone marrow recovery following chemotherapy. A single injection of 5-FU did not alter mouse bone structure but caused acute damage to bone marrow cellularity and vasculature. Single-cell RNA-sequencing of bone marrow mesenchymal lineage cells revealed a substantial reduction in early mesenchymal progenitors and a marked expansion of marrow adipogenic lineage precursors (MALPs) five days post-treatment. Furthermore, 5-FU upregulated the expression of myofibroblast markers in MALPs, indicating a myofibroblast transformation. Using Adipoq-Cre to label MALPs in vivo, we observed that 5-FU transiently increases the number of MALPs in the bone marrow by promoting their proliferation. Immunostaining confirmed the elevated expression of myofibroblast markers in MALPs. By day 14 after 5-FU injection, bone marrow cellularity and vasculature were largely restored; however, the ablation of MALPs significantly impaired this recovery. Taken together, our study uncovers the critical role of MALPs in facilitating bone marrow repair following chemotherapy-induced injury and identifies them as a potential cellular target for treating chemotherapy-induced myelosuppression.

Stromal heterogeneity in the adult lung delineated by single-cell genomics

Stromal cells in the lung provide structural support to other cells and play critical roles in inflammation, repair, and fibrosis after injury. Recent technological advancements in single-cell genomics have tremendously improved our knowledge of stromal heterogeneity in the lung. Stromal heterogeneity in single-cell RNA sequencing data is often conserved across different studies despite the different annotation strategies. Spatial analyses suggest that each stromal subset is characterized by unique anatomic locations in the adult lung. This review overviews the stromal heterogeneity delineated by single-cell RNA sequencing studies and highlights the functional characteristics and locations of each population.

Novel high throughput 3D ECM remodeling assay identifies MEK as key driver of fibrotic fibroblast activity

In fibrotic tissues, activated fibroblasts remodel the collagen-rich extracellular matrix (ECM). Intervening with this process represents a candidate therapeutic strategy to attenuate disease progression. Models that generate quantitative data on 3D fibroblast-mediated ECM remodeling with the reproducibility and throughput needed for drug testing are lacking. Here, we develop a model that fits this purpose and produces combined quantitative information on drug efficacy and cytotoxicity. We use microinjection robotics to design patterns of fibrillar collagen-embedded fibroblast clusters and apply automated microscopy and image analysis to quantify ECM remodeling between-, and cell viability within clusters of TGFβ-activated primary human skin or lung fibroblasts. We apply this assay to compound screening and reveal actionable targets to suppress fibrotic ECM remodeling. Strikingly, we find that after an initial phase of fibroblast activation by TGFβ, canonical TGFβ signaling is dispensable and, instead, non-canonical activation of MEK-ERK signaling drives ECM remodeling. Moreover, we reveal that higher concentrations of two TGFβ receptor inhibitors while blocking canonical TGFβ signaling, in fact stimulate this MEK-mediated profibrotic ECM remodeling activity.

Myofibroblast-like Cells and Junctional Complex Development Play a Role in Mouse Pubic Symphysis Remodeling During Pregnancy and Postpartum

During mouse pregnancy, the pubic symphysis (PS) undergoes a gradual transitioning into an interpubic ligament (IpL) for a successful delivery. After birth, this IpL is rapidly remodeled, returning to the non-pregnant morphology. The PS fibrocartilaginous cells acquire a myofibroblast-like phenotype, characterized by extracellular matrix (ECM) secretion, expression of α-smooth muscle actin (α-SMA), and vimentin. While the presence of myofibroblast-like cells during the IpL remodeling is well described, cell-cell interactions and how this might contribute to the delivery remains poorly understood. This study uses ultrastructure and molecular approaches to investigate cell-cell and cell-ECM junctions during mouse pregnancy and postpartum. Our findings reveal that the intercellular contacts between adjacent IpL myofibroblast-like cells, particularly at late pregnancy stages, are characterized as adherens and GAP junctions. The acquisition of contractile elements by IpL cells, coupled with neighboring cells and the surrounding ECM via junctional complexes, suggests an important role in supporting changes in the mechanical forces generated by pubic bone movements during mouse pregnancy and also in tying the pelvic bones together, which may help the birth canal closure after delivery. Further studies in PS biology may investigate fibroblast to myofibroblast differentiation signaling cascades, which regulate the expression of pro-fibrotic proteins and may provide new insights for preterm labor.

CD105+ fibroblasts support an immunosuppressive niche in women at high risk of breast cancer initiation

BACKGROUND

Aging is the greatest risk factor for breast cancer, and although epithelial cells are the source of carcinomas, epithelial changes alone do not fully explain cancer susceptibility. Fibroblasts and macrophages are key stromal constituents around the cells of origin for cancer in breast tissue. With age, macrophages surrounding terminal ductal lobular units (TDLUs) become increasingly immunosuppressive. CD105+ fibroblasts intercalate within TDLUs, drive luminal differentiation, and give rise to immunosuppressive cancer-associated fibroblasts in other tissues. We propose that differences in fibroblasts are a crucial component of the stroma that shapes cancer susceptibility.

METHODS

Primary peri-epithelial fibroblast cultures were established from prophylactic and reduction mammoplasties from 30 women ranging in age from 16 to 70 years and from BRCA1 mutation carriers. Growth characteristics, transcriptional profiles, differentiation potential, and secreted proteins were profiled for fibroblast subtypes from diverse donors. Co-cultures with fibroblasts, macrophages, and T cells were used to ascertain the functional role played by CD105+ fibroblasts in immune cell modulation.

RESULTS

We found that peri-epithelial CD105+ fibroblasts are enriched in older women as well as women who carry BRCA1 mutations. These CD105+ fibroblasts exhibit robust adipogenesis and secrete factors related to macrophage polarization. Macrophages cocultured with fibroblasts better maintain or enhance polarization states than media alone. CD105+ fibroblasts increased expression of immunosuppressive macrophage genes. CD105+ fibroblasts supported anti-inflammatory macrophage-mediated suppression of T cell proliferation, whereas CD105- fibroblasts significantly reduced the suppressive effect of anti-inflammatory macrophages on T cell proliferation.

CONCLUSIONS

Establishment of a coculture system to dissect the molecular circuits between CD105+ fibroblasts and macrophages that drive immunosuppressive macrophage polarization has broad utility in understanding mammary gland development and events that precede cancer initiation. CD105+ fibroblasts and macrophages may coordinate to suppress immunosurveillance and increase breast cancer susceptibility.

Temporal evolution of fibroblast responses following salivary gland ductal ligation injury

Extracellular matrix remodeling is a natural response to injury but, excessive extracellular matrix accumulation, or fibrosis, is a causative factor in hundreds of diseases that limit organ function, regenerative responses, and can interfere with regenerative therapies. Fibrosis is closely related to inflammation, both of which occur in the salivary glands of patients treated with radiation for head and neck cancers and in patients suffering from autoimmune conditions, such as Sjögren's Disease. Despite the known involvement of fibrosis in disease and the inhibitory effects of fibrosis on tissue regeneration, the mechanisms through which extracellular matrix is elaborated in the salivary gland are poorly understood. Stromal fibroblasts are the primary matrix-producing cells and are known to drive both fibrosis and inflammation. To define the temporal responses of fibroblasts to injury, we induced a temporary obstructive injury though ligation of the primary submandibular and sublingual salivary gland ducts and then performed single-cell RNA sequencing and pathway analysis at timepoints immediately following the injury. Using bioinformatic approaches, we identified three unique fibroblast groups that dynamically respond to the injury. We characterized the changes in matrisomal and inflammatory gene expression over a 7-day time course and identified one group of fibroblasts to be the primary injury-responsive fibrogenic cell type. Understanding how fibroblasts respond at the early and later injury timepoints, along with defining signaling pathways regulated by fibroblasts, could lead to a better understanding of the contribution of fibroblast to acute injury responses to facilitate the development of therapeutics that minimize fibrosis and promote regenerative gland responses in chronic disease states.

Mechanisms of breast cancer metastasis: the role of extracellular matrix

The components of the extracellular matrix (ECM) are dynamic, and they mediate mechanical signals that modulate cellular behaviors. Disruption of the ECM can induce the migration and invasion of cancer cells via specific signaling pathways and cytokines. Metastasis is a leading cause of high mortality in malignancies, and early intervention can improve survival rates. However, breast cancer is frequently diagnosed subsequent to metastasis, resulting in poor prognosis and distant metastasis poses substantial hurdles in therapy. In breast cancer, there is notable tissue remodeling of ECM proteins, with several identified as essential components for metastasis. Moreover, specific ECM molecules, receptors, enzymes, and various signaling pathways play crucial roles in breast cancer metastasis, drug treatment, and resistance. The in-depth consideration of these elements could provide potential therapeutic targets to enhance the survival rates and quality of life for breast cancer patients. This review explores the mechanisms by which alterations in the ECM contribute to breast cancer metastasis and discusses current clinical applications targeting ECM in breast cancer treatment, offering valuable perspectives for future ECM-based therapies.

From Invaginating Site to Deep Lesion: Spatial Transcriptomics Unravels Ectopic Endometrial Penetration Features in Adenomyosis

Adenomyosis, characterized by clinical intractability, significantly impacts female fertility and life quality due to the absence of definitive diagnostic markers and effective treatment options. The invagination theory is a primary hypothesis for adenomyosis, but the underlying molecular mechanisms remain unclear. In this study, a spatial transcriptional landscape of adenomyosis with an evident invagination structure is mapped from the endometrial invaginating site to ectopic lesions utilizing spatial transcriptomics and single-cell RNA sequencing. In addition, the authors employ bulk RNA sequencing deconvolution to assess the significance of core spatial ecotypes, use histological techniques to target specific cell types, and conduct in vitro experiments for validation. At the invagination site, SFRP5+ epithelial cells promote endometrial proliferation and angiogenesis through secretion of IHH. During the invading process, ESR1+ smooth muscle cells (SMCs) facilitate invasion by creating migratory tracts via collagen degradation. Within deep lesions, CNN1+ stromal fibroblasts induce fibrosis by undergoing a fibroblast-to-myofibroblast transition (FMT) in response to pathologic profibrogenic signals in the microenvironment of lesions. This work offers an in-depth understanding of the molecular mechanisms underlying the pathological processes of adenomyosis with invagination. Furthermore, this work introduces the first transcriptomics web source of adenomyosis, which is expected to be a valuable resource for subsequent research.

Fibroproliferative conditions: the 3R approach bridging fibrosis and tumors

Soft-tissue fibroproliferative conditions (FPCs) affect many organs. All demonstrate the accumulation of (myo)fibroblasts and extracellular matrix. Currently, FPCs are classified according to the affected body site/organ. To promote research into the etiological mechanisms that drive pathological FPCs, we propose a new, more clinically grounded, FPC classification that is based on the intent and severity of the fibroproliferation. There are three categories: responsive, replacement, and reconstructive FPCs. Reconstructive FPCs (e.g., keloids) have quasi-neoplastic behaviors, including local invasiveness, and serve as a bridge between fibrosis and cancers. Comparisons of reconstructive FPCs to both cancers and the other FPC categories may help elucidate their pathogenic cellular properties, microenvironmental components, and intracellular-signaling mechanisms. Thus, the new FPC classification may promote research in the fibrosis field.

CD105+ fibroblasts support an immunosuppressive niche in women at high risk of breast cancer initiation

BACKGROUND

Aging is the greatest risk factor for breast cancer, and although epithelial cells are the source of carcinomas, epithelial changes alone do not fully explain cancer susceptibility. Fibroblasts and macrophages are key stromal constituents around the cells of origin for cancer in breast tissue. With age, macrophages surrounding terminal ductal lobular units (TDLUs) become increasingly immunosuppressive. CD105 + fibroblasts intercalate within TDLUs, drive luminal differentiation, and give rise to immunosuppressive cancer-associated fibroblasts in other tissues. We propose that differences in fibroblasts are a crucial component of the stroma that shapes cancer susceptibility.

METHODS

Primary fibroblast cultures were established from prophylactic and reduction mammoplasties from women ranging in age from 16 to 70 years and breast cancer risk ( BRCA1 mutation carriers). Growth characteristics, transcriptional profiles, differentiation potential, and secreted proteins were profiled for fibroblast subtypes from diverse donors. Co-cultures with fibroblasts, monocytes, macrophages, and T cells were used to ascertain the functional role played by CD105 + fibroblasts in immune cell modulation.

RESULTS

We found that peri-epithelial CD105 + fibroblasts are enriched in older women as well as women who carry BRCA1 mutations. These CD105 + fibroblasts exhibit robust adipogenesis and secrete factors related to macrophage polarization. Macrophages cocultured with fibroblasts better maintain or enhance polarization states than media alone. CD105 + fibroblasts increased expression of immunosuppressive macrophage genes. CD105 + fibroblasts supported anti-inflammatory macrophage-mediated suppression of T cell proliferation, whereas CD105 - fibroblasts significantly reduced the suppressive effect of anti-inflammatory macrophages on T cell proliferation.

CONCLUSIONS

Establishment of a coculture system to dissect the molecular circuits between CD105 + fibroblasts and macrophages that drive immunosuppressive macrophage polarization has broad utility in understanding mammary gland development and events that precede cancer initiation. CD105 + fibroblasts and macrophages may coordinate to suppress immunosurveillance and increase breast cancer susceptibility.

Advances in Etiology and Prevention of Capsular Contracture After Breast Implantation

Capsular contracture (CC) is one of the most common complications of breast implant usage in breast augmentation or reconstruction. The CC approach can cause breast hardening, pain, and varying degrees of deformity, affecting the quality of life of patients. Considerably, it has become one of the most common reasons for frequent surgeries. Nonetheless, the etiology and pathogenesis of CC remain unclear. Moreover, there exist still a lot of uncertainties regarding prevention and treatment measures. In this article, we present discussions on the research status of the etiology, pathogenesis, prevention, and treatment measures of CC. In summary, this study provides a reference for further research on CC and clinical use.Level of Evidence V This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Fibrosis: cross-organ biology and pathways to development of innovative drugs

Fibrosis is a pathophysiological mechanism involved in chronic and progressive diseases that results in excessive tissue scarring. Diseases associated with fibrosis include metabolic dysfunction-associated steatohepatitis (MASH), inflammatory bowel diseases (IBDs), chronic kidney disease (CKD), idiopathic pulmonary fibrosis (IPF) and systemic sclerosis (SSc), which are collectively responsible for substantial morbidity and mortality. Although a few drugs with direct antifibrotic activity are approved for pulmonary fibrosis and considerable progress has been made in the understanding of mechanisms of fibrosis, translation of this knowledge into effective therapies continues to be limited and challenging. With the aim of assisting developers of novel antifibrotic drugs, this Review integrates viewpoints of biologists and physician-scientists on core pathways involved in fibrosis across organs, as well as on specific characteristics and approaches to assess therapeutic interventions for fibrotic diseases of the lung, gut, kidney, skin and liver. This discussion is used as a basis to propose strategies to improve the translation of potential antifibrotic therapies.

The involvement of YAP-TGFβ-SMAD-mediated fibrosis in primary inferior oblique overaction

This study investigates the involvement of fibrosis in primary inferior oblique overaction (PIOOA), a strabismus characterized by excessive upward eye rotation. First, we identified extensive fibrotic changes in inferior oblique (IO) muscles in PIOOA patients compared to normal controls. A strong positive correlation was clinically established between the severity of PIOOA and the expression of collagen type I alpha 1 chain (COL1A1). COL1A1 levels correlate with preoperative and postoperative clinical grading of PIOOA and the degree of fundus deviation, as measured by disk-foveal angle (DFA). Moreover, immunofluorescence in IO muscle sections of PIOOA patients confirmed activation of fibro/adipogenic progenitors (FAPs) and suggested increased activation of YAP. Interestingly, the TGFβ signaling pathway also exhibited activation, with a notable increase observed in the expression of TGFβ2 in the PIOOA group. Subsequently, we first isolated FAPs from human IO muscles and validated these findings. In vitro, YAP overexpression promoted the differentiation of FAPs into myofibroblasts, exacerbating fibrotic changes. However, knockdown of YAP inhibited the activation of FAPs and fibrogenesis induced by TGFβ2. More importantly, we found TGFβ2 treatment promoted the activation of YAP simultaneously, and the overexpression or inhibition of YAP also affected TGFβ2 production and Smad phosphorylation, indicating a close connection between the two. Remarkably, verteporfin was observed to block both pathways effectively. Taken together, these findings suggest that the YAP-TGFβ-SMAD signaling cascade plays a key role in the pathophysiology of PIOOA through FAP-mediated fibrosis. Targeting these pathways may therefore provide a potential therapeutic strategy for managing PIOOA by alleviating muscle fibrosis.

Direct fibroblast reprogramming: an emerging strategy for treating organic fibrosis

Direct reprogramming has garnered considerable attention due to its capacity to directly convert differentiated cells into desired cells. Fibroblasts are frequently employed in reprogramming studies due to their abundance and accessibility. However, they are also the key drivers in the progression of fibrosis, a pathological condition characterized by excessive extracellular matrix deposition and tissue scarring. Furthermore, the initial stage of reprogramming typically involves deactivating fibrotic pathways. Hence, direct reprogramming offers a valuable method to regenerate target cells for tissue repair while simultaneously reducing fibrotic tendencies. Understanding the link between reprogramming and fibrosis could help develop effective strategies to treat damaged tissue with a potential risk of fibrosis. This review summarizes the advances in direct reprogramming and reveals their anti-fibrosis effects in various organs such as the heart, liver, and skin. Furthermore, we dissect the mechanisms of reprogramming influenced by fibrotic molecules including TGF-β signaling, mechanical signaling, inflammation signaling, epigenetic modifiers, and metabolic regulators. Innovative methods for fibroblast reprogramming like small molecules, CRISPRa, modified mRNA, and the challenges of cellular heterogeneity and senescence faced by in vivo direct reprogramming, are also discussed.

Adipose-Derived Stem Cell Exosomes Promote Scar-Free Healing of Diabetic Wounds via miR-204-5p/TGF-β1/Smad Pathway

Numerous researches have demonstrated the therapeutic potential of adipose-derived stem cell exosomes (ADSC-Exos) in promoting wound healing. In this study, we aimed to investigate the impact of ADSC-Exos on diabetic wound fibroblasts and elucidate its possible mechanisms. CCK-8, Edu, cell scratch, and Transwell tests were used to evaluate the function of ADSC-Exos on rat skin fibroblasts (RSFs) in high-glucose (HG) medium. The targeting effect of ADSC-Exo-derived microRNA (miRNA) and TGF-β1 was assessed using bioinformatic analysis and then confirmed with western blot and dual luciferase reporter assays. ADSC-Exos, miR-204-5p mimic, and anti-miR-204-5p mimic were used to stimulate RSFs, and the levels of TGF-β1/Smad pathway were analyzed by western blot. In vivo, digital photo and tissue section staining were used to evaluate the therapeutic effect of ADSC-Exos on diabetic wounds. The data showed that ADSC-Exos enhance the proliferation and migration of fibroblasts under HG conditions, reduce excessive myofibroblast differentiation and collagen deposition, and promote scarless healing of diabetic wounds. Additionally, miR-204-5p in ADSC-Exos targets TGF-β1 to inhibit p-Smad2/3, Col I, and alpha-smooth muscle actin (α-SMA), thereby reducing fibrosis. These findings suggest that ADSC-Exos have potential prospects for promoting diabetic wound healing.

PD-L1 upregulation in activated fibroblasts promotes silica particle-induced pulmonary fibrosis

Silicosis is a severe interstitial lung disease resulting from prolonged exposure to silica dust in working environment, characterized by inflammation and fibrosis. This condition is closely associated with immune dysregulation, although the precise regulatory mechanisms remain elusive. Immune checkpoints (ICs) comprise receptor-ligand pairs crucial for immune cell activation and coordination of immune responses. Among these, PD-1 and its ligand PD-L1 have garnered significant attention in tumor research and have recently been implicated in the regulation of fibrotic diseases. Nonetheless, their involvement in silicosis remains unexplored. In this study, we observed a global upregulation of PD-1 and PD-L1 expression concomitant with the progression of silicosis, exhibiting cell specificity. Targeting PD-1/PD-L1 signaling mitigated silicosis in mice by modulating T cell homeostasis, macrophage polarization, and activation of fibrotic effector cells. Notably, PD-L1 expression on activated fibroblasts emerged as a pivotal driver of silicosis progression. Mechanistically, elevated PD-L1 levels in fibroblast activation fostered a positive feedback loop by binding to p-Smad2/3 and p-STAT3 proteins, thereby facilitating their nuclear translocation and augmenting protein stability, ultimately promoting fibroblast transdifferentiation. Consistently, knockdown of PD-L1 in lung fibroblasts significantly ameliorated silicosis in mice. In summary, PD-1/PD-L1 signaling mediates critical profibrotic signals during the progression of silicosis.

Growth differentiation factor 15 is a glucose-downregulated gene acting as the cross talk between stroma and cancer cells of the human bladder

Hyperglycemia and hyperglycosuria, two primary characteristics of diabetes mellitus, may increase the risk of cancer initiation, particularly for bladder cancer. The effectiveness of metformin, a common antidiabetic agent, is determined by its ability to induce growth differentiation factor 15 (GDF15). However, the mechanism of the GDF15 in relation to glucose, which influences the tumor microenvironment in the human bladder, is not fully understood. This study explores the potential roles of GDF15 in response to glucose in the human bladder. High glucose treatment (30 mM) enhanced phosphorylation of AKT at S473 and AMP-activated protein kinase α1/2 (AMPKα1/2) at S485 to block the counteracting effect of metformin on the AMPK activity in bladder cancer and stroma [human bladder stromal fibroblast (HBdSF) and human bladder smooth muscle cell (HBdSMC)] cells compared with normal glucose treatment (5 mM). Metformin modulated the expressions of GDF15, NDRG1, Maspin, and epithelial-to-mesenchymal transition (EMT) markers to attenuate cell proliferation and invasion of bladder cancer cells. Caffeic acid phenethyl ester (CAPE), like metformin, behaves as an inducer of AMPK activity to stimulate GDF15 expression. Knockdown of GDF15 blocked the downregulation of CAPE on the contraction of HBdSMCs. Both CAPE-induced GDF15 expression and the supernatant from bladder cancer cells with overexpressing GDF15 impeded the HBdSF and HBdSMC migration, suggesting that CAPE-upregulated GDF15 blocked the cell migration. These findings reveal that high glucose treatment inhibits the counteracting effects of either metformin or CAPE on the AMPK activity and GDF15 is downregulated by glucose and induced by metformin and CAPE in both stroma and cancer cells. Furthermore, GDF15 is an antitumor gene facilitating communication between stroma and cancer cells in the human bladder.NEW & NOTEWORTHY This study investigates the counteraction of either CAPE or metformin with the AMPK activity increasing GDF15 expression in human bladder cells. The findings are the first study to indicate the secretion of GDF15 from cancer and stroma cells via autocrine or paracrine mechanisms. Our study suggests that GDF15, an antitumor gene in the human bladder induced by AMPK inducers, acts as a communication link between stroma and cancer cells in the human bladder.

Tension-induced organelle stress: an emerging target in fibrosis

Fibrosis accounts for approximately one-third of disease-related deaths globally. Current therapies fail to cure fibrosis, emphasizing the need to identify new antifibrotic approaches. Fibrosis is defined by the excessive accumulation of extracellular matrix (ECM) and resultant stiffening of tissue stroma. This stiffening appropriates actomyosin-mediated mechanical tension within cells to ultimately affect cell fate decisions and function. Recent studies demonstrate that subcellular organelles are physically connected to the actin cytoskeleton and sensitive to mechanoperturbations. These insights highlight mechanisms that may contribute to the chronic organelle stress in many fibrotic diseases, including those of the lung and liver. In this review, we discuss the hypothesis that a stiffened fibrotic ECM corrupts intracellular mechanical tension to compromise organelle homeostasis. We summarize potential therapeutics that could intervene in this mechanical dialog and that may have clinical benefit for resolving pathological organelle stress in fibrosis.

A Core of Keratocan-Negative Cells Survives in Old Corneal Scars

Corneal scars originate from keratocyte-derived fibroblasts and myofibroblasts that are ultimately cleared through apoptosis or revert to keratocytes. A mouse model expressing the keratocyte lineage-specific reporter KeraRT/tetO-Cre/mTmG (I-KeramTmG) was used to elucidate cell phenotype dynamics during scar maturation. In this model, tdTomato (red) is expressed in all keratocan-negative cells, while enhanced green fluorescent protein (green) is expressed only by keratocytes. A 1-mm full-thickness keratotomy was generated in adult I-KeramTmG mice. The presence of keratocytes was determined at 3, 6, and 10 months after injury. At 3 and 6 months, few green cells were visualized at the scar borders, while few or no green cells were seen in the central (core) scar. At 10 months, a few green cells and a majority of red cells were observed throughout the scar. Proliferation of stromal cells after injury was studied by 5-ethynyl-2'-deoxyuridine labeling and Ki-67 staining. Both assays showed proliferation only during the first 2 weeks after injury. Second harmonic generation microscopy showed thickened and irregularly arranged collagen fibers in scars, suggesting that neither extracellular matrix organization nor cell phenotype had changed significantly at 10 months after injury. Findings from in vivo experiments suggest that in old corneal scars, a nonkeratocyte phenotype persists in an abnormal matrix with unique characteristics that probably prevent the regression of fibroblasts and myofibroblasts to keratocytes or invasion of surrounding keratocytes.

Inflammatory myofibroblastic tumour of the larynx: report of a case

Only 0.3-1% of laryngeal cancer are non-squamous cell neoplasms. Of these, a rare entity is inflammatory myofibroblastic tumour (IMT), in which anaplastic lymphoma kinase-1 (ALK-1) is frequently expressed. Just 50 cases of IMT have been reported. Therefore, many otolaryngologists may be unfamiliar with this type of tumour and be prone to its over- or undertreatment.We report a case of ALK-1-negative IMT treated with transoral endoscopic excision and disease-free 6 months after surgery.

Methylglyoxal-Stimulated Mesothelial Cells Prompted Fibroblast-to-Proto-Myofibroblast Transition

During long-term peritoneal dialysis, peritoneal fibrosis (PF) often happens and results in ultrafiltration failure, which directly leads to the termination of dialysis. The accumulation of extracellular matrix produced from an increasing number of myofibroblasts was a hallmark characteristic of PF. To date, glucose degradation products (GDPs, i.e., methylglyoxal (MGO)) that appeared during the heating and storage of the dialysate are considered to be key components to initiating PF, but how GDPs lead to the activation of myofibroblast in fibrotic peritoneum has not yet been fully elucidated. In this study, mesothelial cell line (MeT-5A) and fibroblast cell line (MRC-5) were used to investigate the transcriptomic and proteomic changes to unveil the underlying mechanism of MGO-induced PF. Our transcriptomic data from the MGO-stimulated mesothelial cells showed upregulation of genes involved in pro-inflammatory, apoptotic, and fibrotic pathways. While no phenotypic changes were noted on fibroblasts after direct MGO, supernatant from MGO-stimulated mesothelial cells promoted fibroblasts to change into proto-myofibroblasts, activated fibroblasts in the first stage toward myofibroblasts. In conclusion, this study showed that MGO-stimulated mesothelial cells promoted fibroblast-to-proto-myofibroblast transition; however, additional involvement of other factors or cells (e.g., macrophages) may be needed to complete the transformation into myofibroblasts.

Biomimetic Topological Micropattern Arrays Regulate the Heterogeneity of Cellular Fates in Lung Fibroblasts between Fibrosis and Invasion

Idiopathic pulmonary fibrosis (IPF) is characterized by persistent tissue injury, dysregulated wound healing, and extracellular matrix (ECM) deposition by myofibroblasts (MFs) through the fibroblast-to-myofibroblast transition (FMT). Implicit in the FMT process are changes in the ECM and cellular topology, but their relationship with the lung fibroblast phenotype has not been explored. We engineered topological mimetics of alignment cues (anisotropy/isotropy) using lung decellularized ECM micropattern arrays and investigated the effects of cellular topology on cellular fates in MRC-5 lung fibroblasts. We found that isotropic MRC-5 cells presented changes of the cytoskeleton, increased cell-cell adhesions and a multicellular architecture with increased overlap, changes in actin-myosin development, and enhanced focal adhesion and cell junction with random alignment. Besides, anisotropic fibroblasts were activated into a regular phenotype with an ECM remodeling profile. In contrast, isotropic fibroblasts developed a highly invasive phenotype expressing molecules, including CD274/programmed death-ligand 1 (PD-L1), cellular communication network factor 2 (CCN2)/connective tissue growth factor (CTGF), hyaluronan synthase 2 (HAS2), and semaphorin 7A (SEMA7A), but with downregulated matrix genes. Moreover, isotropic fibroblasts also showed higher expressions of Ki-67 and cyclin D1 (CCND1), resistance to apoptosis/senescence, and decreased autophagy. The topology regulated the cellular heterogeneity and resulted in positive feedback between changes in the cellular phenotype and the ECM structure, which may aggravate fibrosis and lead to a priming of malignant microenvironment during carcinogenesis. Using the versatile platform of micropattern array, we can not only visualize the interaction mechanism between cells and the ECM but also select potential clinical targets for diagnosis and therapeutics.

The role of the PI3K/AKT/mTOR pathway in mediating PD-L1 upregulation during fibroblast transdifferentiation

Silicosis is a progressive interstitial lung disease characterized by diffuse pulmonary fibrosis. The transdifferentiation of lung fibroblasts into myofibroblasts is a key cellular event driving the progression of silicosis fibrosis. Recent studies have shown that PD-L1 expression is significantly upregulated in activated fibroblasts, and PD-L1 plays a crucial role in mediating fibroblast transdifferentiation. This study aims to elucidate the molecular mechanisms regulating PD-L1 expression in fibroblasts and analyze the functional significance of PD-L1 upregulation in fibroblast activity and silicosis fibrosis. In this research, an in vitro model of TGF-β1-induced NIH-3 T3 fibroblast transdifferentiation was established. Small molecule inhibitors, siRNA, and plasmids were used to interfere with the PI3K/AKT/mTOR signaling pathway and PD-L1 expression. It was found that TGF-β1 stimulation increased PD-L1 expression in fibroblasts, while blocking the PI3K/AKT/mTOR pathway inhibited this upregulation. Knockdown of PD-L1 significantly inhibited fibroblast transdifferentiation and impeded TGF-β1-induced activation of the PI3K/AKT/mTOR pathway, whereas PD-L1 overexpression had the opposite effect. Additionally, PD-L1 protein in fibroblasts undergoes ubiquitin-proteasome-mediated degradation, negatively regulating PD-L1 upregulation. In vivo, adeno-associated virus was used to specifically knockdown PD-L1 in mouse lung fibroblasts, resulting in significantly reduced lung tissue damage and fibrosis in silicosis mice. This effect was associated with the involvement of the PI3K/AKT/mTOR pathway. In summary, PD-L1 expression in fibroblasts is upregulated during transdifferentiation, a process regulated by the PI3K/AKT/mTOR pathway. Upregulated PD-L1 enhances PI3K/AKT/mTOR signaling through positive feedback, sustaining fibroblast activation. Ubiquitin-proteasome-mediated protein degradation may serve as a negative feedback mechanism maintaining PD-L1 homeostasis.

Mechanistic insights into intrauterine adhesions

Intrauterine adhesions (IUA), also known as Asherman's syndrome, arise from damage to the basal layer of the endometrium, frequently caused by intrauterine interventions. This damage leads to nonregenerative healing of endometrium resulting in replacement by fibrous connective tissue, which bring about the adherence of opposing endometrium to render the uterine cavity and/or cervical canal partially or completely obliterated. IUA is a common cause of the refractory uterine infertility. Hysteroscopy is the gold standard for diagnosis of IUA. However, the method of accurately predicting the likelihood of achieving a live birth in the future remains established. Classical treatments have shown limited success, particularly in severe cases. Therefore, utilizing new research methods to deepen the understanding of the pathogenesis of IUA will facilitate the new treatment approaches to be found. In this article we briefly described the advances in the pathogenesis of IUA, with focus on inflammation and parenchymal cellular homeostasis disruption, defects in autophagy and the role of ferroptosis, and we also outlined the progress in IUA therapy.

p53 and the E3 Ubiquitin Ligase MDM2 in Glaucomatous Lamina Cribrosa Cells

Lamina cribrosa (LC) cells play an integral role in extracellular matrix remodeling and fibrosis in human glaucoma. LC cells bear similarities to myofibroblasts that adopt an apoptotic-resistant, proliferative phenotype, a process linked to dysregulation of tumor suppressor-gene p53 pathways, including ubiquitin-proteasomal degradation via murine-double-minute-2 (MDM2). Here, we investigate p53 and MDM2 in glaucomatous LC cells. Primary human LC cells were isolated from glaucomatous donor eyes (GLC) and age-matched normal controls (NLC) (n = 3 donors/group). LC cells were cultured under standard conditions ± 48-h treatment with p53-MDM2-interaction inhibitor RG-7112. Markers of p53-MDM2, fibrosis, and apoptosis were analyzed by real-time polymerase chain reaction (qRT-PCR), western blotting, and immunofluorescence. Cellular proliferation and viability were assessed using colorimetric methyl-thiazolyl-tetrazolium salt assays (MTS/MTT). In GLC versus NLC cells, protein expression of p53 was significantly decreased (p < 0.05), MDM2 was significantly increased, and immunofluorescence showed reduced p53 and increased MDM2 expression in GLC nuclei. RG-7112 treatment significantly increased p53 and significantly decreased MDM2 gene and protein expression. GLC cells had significantly increased protein expression of αSMA, significantly decreased caspase-3 protein expression, and significantly increased proliferation after 96 h. RG-7112 treatment significantly decreased COL1A1 and αSMA, significantly increased BAX and caspase-3 gene expression, and significantly decreased proliferation in GLC cells. MTT-assay showed equivocal cellular viability in NLC/GLC cells with/without RG-7112 treatment. Our data suggests that proliferation and the ubiquitin-proteasomal pathway are dysregulated in GLC cells, with MDM2-led p53 protein degradation negatively impacting its protective role.

Unraveling the Immune Web: Advances in SMI Capsular Fibrosis from Molecular Insights to Preclinical Breakthroughs

Breast implant surgery has evolved significantly, yet challenges such as capsular contracture remain a persistent concern. This review presents an in-depth analysis of recent advancements in understanding the immune mechanisms and clinical implications associated with silicone mammary implants (SMIs). The article systematically examines the complex interplay between immune responses and capsular fibrosis, emphasizing the pathophysiological mechanisms of inflammation in the etiology of this fibrotic response. It discusses innovations in biomaterial science, including the development of novel anti-biofilm coatings and immunomodulatory surfaces designed to enhance implant integration and minimize complications. Emphasis is placed on personalized risk assessment strategies, leveraging molecular insights to tailor interventions and improve patient outcomes. Emerging therapeutic targets, advancements in surgical techniques, and the refinement of post-operative care are also explored. Despite notable progress, challenges such as the variability in immune responses, the long-term efficacy of new interventions, and ethical considerations remain. Future research directions are identified, focusing on personalized medicine, advanced biomaterials, and bridging preclinical findings with clinical applications. As we advance from bench to bedside, this review illuminates the path forward, where interdisciplinary collaboration and continued inquiry weave together to enhance the art and science of breast implant surgery, transforming patient care into a realm of precision and excellence.

Label-free three-dimensional imaging and quantitative analysis of living fibroblasts and myofibroblasts by holotomographic microscopy

Holotomography (HT) is a cutting-edge fast live-cell quantitative label-free imaging technique. Based on the principle of quantitative phase imaging, it combines holography and tomography to record a three-dimensional map of the refractive index, used as intrinsic optical and quantitative imaging contrast parameter of biological samples, at a sub-micrometer spatial resolution. In this study HT has been employed for the first time to analyze the changes of fibroblasts differentiating towards myofibroblasts - recognized as the main cell player of fibrosis - when cultured in vitro with the pro-fibrotic factor, namely transforming growth factor-β1. In parallel, F-actin, vinculin, α-smooth muscle actin, phospho-myosin light chain 2, type-1 collagen, peroxisome proliferator-activated receptor-gamma coactivator-1α expression and mitochondria were evaluated by confocal laser scanning microscopy. Plasmamembrane passive properties and transient receptor potential canonical channels' currents were also recorded by whole-cell patch-clamp. The fluorescence images and electrophysiological results have been compared to the data obtained by HT and their congruence has been discussed. HT turned out to be a valid approach to morphologically distinguish fibroblasts from well differentiated myofibroblasts while obtaining objective measures concerning volume, surface area, projection area, surface index and dry mass (i.e., the mass of the non-aqueous content inside the cell including proteins and subcellular organelles) of the entire cell, nuclei and nucleoli with the major advantage to monitor outer and inner features in living cells in a non-invasive, rapid and label-free approach. HT might open up new research opportunities in the field of fibrotic diseases. RESEARCH HIGHLIGHTS: Holotomography (HT) is a label-free laser interferometric imaging technology exploiting the intrinsic optical property of cells namely refractive index (RI) to enable a direct imaging and analysis of whole cells or intracellular organelles. HT turned out a valid approach to distinguish morphological features of living unlabeled fibroblasts from differentiated myofibroblasts. HT provided quantitative information concerning volume, surface area, projection area, surface index and dry mass of the entire fibroblasts/myofibroblasts, nuclei and nucleoli.

SMI-Capsular Fibrosis and Biofilm Dynamics: Molecular Mechanisms, Clinical Implications, and Antimicrobial Approaches

Silicone mammary implants (SMIs) frequently result in capsular fibrosis, which is marked by the overproduction of fibrous tissue surrounding the implant. This review provides a detailed examination of the molecular and immunological mechanisms driving capsular fibrosis, focusing on the role of foreign body responses (FBRs) and microbial biofilm formation. We investigate how microbial adhesion to implant surfaces and biofilm development contribute to persistent inflammation and fibrotic responses. The review critically evaluates antimicrobial strategies, including preoperative antiseptic protocols and antimicrobial-impregnated materials, designed to mitigate infection and biofilm-related complications. Additionally, advancements in material science, such as surface modifications and antibiotic-impregnated meshes, are discussed for their potential to reduce capsular fibrosis and prevent contracture of the capsule. By integrating molecular insights with clinical applications, this review aims to elucidate the current understanding of SMI-related fibrotic responses and highlight knowledge gaps. The synthesis of these findings aims to guide future research directions of improved antimicrobial interventions and implant materials, ultimately advancing the management of capsular fibrosis and enhancing patient outcomes.

Fibrocyte: A missing piece in the pathogenesis of fibrous epulis

OBJECTIVES

To explore the role of fibrocytes in the recurrence and calcification of fibrous epulides.

METHODS

Different subtypes of fibrous epulides and normal gingival tissue specimens were first collected for histological and immunofluorescence analyses to see if fibrocytes were present and whether they differentiated into myofibroblasts and osteoblasts upon stimulated by transforming growth factor-β1 (TGF-β1). Electron microscopy and elemental analysis were used to characterize the extracellular microenvironment in different subtypes of fibrous epulides. Human peripheral blood mononuclear cells (PBMCs) were subsequently isolated from in vitro models to mimic the microenvironment in fibrous epulides to identify whether TGF-β1 as well as the calcium and phosphorus ion concentration in the extracellular matrix (ECM) of a fibrous epulis trigger fibrocyte differentiation.

RESULTS

Fibrous epulides contain fibrocytes that accumulate in the local inflammatory environment and have the ability to differentiate into myofibroblasts or osteoblasts. TGF-β1 promotes fibrocytes differentiation into myofibroblasts in a concentration-dependent manner, while TGF-β1 stimulates the fibrocytes to differentiate into osteoblasts when combined with a high calcium and phosphorus environment.

CONCLUSIONS

Our study revealed fibrocytes play an important role in the fibrogenesis and osteogenesis in fibrous epulis, and might serve as a therapeutic target for the inhibition of recurrence of fibrous epulides.

Heterogeneity in extracellular matrix and immune microenvironment of anterior vaginal wall revealed by single-cell sequencing in women with stress urinary incontinence

Stress urinary incontinence (SUI), characterized by involuntary urine leakage during increased abdominal pressure, remains poorly understood regarding its pathophysiology and treatment. In this study, we utilized single-cell sequencing to analyze the transcriptomic profiles of different cell types in anterior vaginal wall of SUI patients, aiming to explore the heterogeneity of the extracellular matrix (ECM) and immune microenvironment in SUI pathogenesis. Our results identified eleven cell types, including connective tissue cells, immune cells, and glial cells. Specifically, fibroblasts, smooth muscle cells, epithelial cells and T cells displayed transcriptional characteristics highly relevant to SUI pathogenesis. We observed that most cell types participate in ECM metabolism and immune-inflammatory responses, indicating a synergistic role of multiple vaginal cell types in SUI. Furthermore, altered intercellular communication, particularly between fibroblasts and T cells, was noted in SUI. This study provides novel single-cell insights into SUI and identifies potential biomarkers and therapeutic targets for future research.

Classifying cancer-associated fibroblasts-The good, the bad, and the target

Cancer-associated fibroblasts (CAFs) are heterogeneous and ubiquitous stromal cells within the tumor microenvironment (TME). Numerous CAF types have been described, typically using single-cell technologies such as single-cell RNA sequencing. There is no general classification system for CAFs, hampering their study and therapeutic targeting. We propose a simple CAF classification system based on single-cell phenotypes and spatial locations of CAFs in multiple cancer types, assess how our scheme fits within current knowledge, and invite the CAF research community to further refine it.

On-Demand Bioactivation of Inert Materials With Plasma-Polymerized Nanoparticles

Conventional gas plasma treatments are crucial for functionalizing materials in biomedical applications, but have limitations hindering their broader use. These methods require exposure to reactive media under vacuum conditions, rendering them unsuitable for substrates that demand aqueous environments, such as proteins and hydrogels. In addition, complex geometries are difficult to treat, necessitating extensive customization for each material and shape. To address these constraints, an innovative approach employing plasma polymer nanoparticles (PPN) as a versatile functionalization tool is proposed. PPN share similarities with traditional plasma polymer coatings (PPC) but offer unique advantages: compatibility with aqueous systems, the ability to modify complex geometries, and availability as off-the-shelf products. Robust immobilization of PPN on various substrates, including synthetic polymers, proteins, and complex hydrogel structures is demonstrated in this study. This results in substantial improvements in surface hydrophilicity. Materials functionalization with arginylglycylaspartic acid (RGD)-loaded PPN significantly enhances cell attachment, spreading, and substrate coverage on inert scaffolds compared to passive RGD coatings. Improved adhesion to complex geometries and subsequent differentiation following growth factor exposure is also demonstrated. This research introduces a novel substrate functionalization approach that mimics the outcomes of plasma coating technology but vastly expands its applicability, promising advancements in biomedical materials and devices.

A Comprehensive Flow Cytometry Panel for Analysis of Idiopathic Subglottic Stenosis

OBJECTIVE

To present a comprehensive flow cytometry panel for idiopathic subglottic stenosis (iSGS).

STUDY DESIGN

Controlled ex vivo cohort study.

SETTING

Tertiary care academic hospital in a metropolitan area.

METHODS

Flow cytometry and single-cell RNA sequencing were performed on 9 paired normal and scar tissue samples from iSGS patients. Flow cytometry was used to assess the presence of myeloid (CD11b, CD14, CD15, Siglec8), lymphoid (CD3, CD4, CD8, gamma delta [γδ], FOXP3), endothelial (CD31), fibroblast (CD90, SMA), and epithelial (CD326, CK5) markers.

RESULTS

On flow cytometry, iSGS scar is characterized by an increased presence of myeloid, lymphoid, endothelial, and fibroblast cell types, but a decreased presence of epithelial cells. In the myeloid lineage, iSGS scar samples demonstrated increased CD11b+ monocytes (P < .001), Siglec8+ eosinophils (P = .03), and CD14+ monocytes (P = .02). In the lymphoid lineage, iSGS scar demonstrated increased CD3+ T-cells (P < .001), CD4+ helper T-cells (P < .001), γδ+ T-cells (P < .001), and FOXP3+ regulatory T-cells (P = .002). iSGS scar exhibited specific increases in CD90+ (P = .04) and SMA+ (P < .001) fibroblasts but decreased CD326+ (E-cadherin) epithelial cells (P = .01) relative to normal samples.

CONCLUSION

We present a comprehensive flow cytometry panel for iSGS. This flow panel may serve as a common platform among airway scientists to elucidate the cellular mechanisms underpinning iSGS and other upper airway pathologies. Scar iSGS samples demonstrate a distinct cellular profile relative to normal iSGS specimens, exhibiting increased fibroblast, endothelial, and inflammatory cell types but decreased epithelium.

Dexamethasone induces trabecular meshwork cell myofibroblast transdifferentiation through ARHGEF26

Glucocorticoid use may cause elevated intraocular pressure, leading to the development of glucocorticoid-induced glaucoma (GIG). However, the mechanism of GIG development remains incompletely understood. In this study, we subjected primary human trabecular meshwork cells (TMCs) and mice to dexamethasone treatment to mimic glucocorticoid exposure. The myofibroblast transdifferentiation of TMCs was observed in cellular and mouse models, as well as in human trabecular mesh specimens. This was demonstrated by the cytoskeletal reorganization, alterations in cell morphology, heightened transdifferentiation markers, increased extracellular matrix deposition, and cellular dysfunction. Knockdown of Rho guanine nucleotide exchange factor 26 (ARHGEF26) expression ameliorated dexamethasone-induced changes in cell morphology and upregulation of myofibroblast markers, reversed dysfunction and extracellular matrix deposition in TMCs, and prevented the development of dexamethasone-induced intraocular hypertension. And, this process may be related to the TGF-β pathway. In conclusion, glucocorticoids induced the myofibroblast transdifferentiation in TMCs, which played a crucial role in the pathogenesis of GIG. Inhibition of ARHGEF26 expression protected TMCs by reversing myofibroblast transdifferentiation. This study demonstrated the potential of reversing the myofibroblast transdifferentiation of TMCs as a new target for treating GIG.

The Myofibroblast Fate of Therapeutic Mesenchymal Stromal Cells: Regeneration, Repair, or Despair?

Mesenchymal stromal cells (MSCs) can be isolated from various tissues of healthy or patient donors to be retransplanted in cell therapies. Because the number of MSCs obtained from biopsies is typically too low for direct clinical application, MSC expansion in cell culture is required. However, ex vivo amplification often reduces the desired MSC regenerative potential and enhances undesired traits, such as activation into fibrogenic myofibroblasts. Transiently activated myofibroblasts restore tissue integrity after organ injury by producing and contracting extracellular matrix into scar tissue. In contrast, persistent myofibroblasts cause excessive scarring-called fibrosis-that destroys organ function. In this review, we focus on the relevance and molecular mechanisms of myofibroblast activation upon contact with stiff cell culture plastic or recipient scar tissue, such as hypertrophic scars of large skin burns. We discuss cell mechanoperception mechanisms such as integrins and stretch-activated channels, mechanotransduction through the contractile actin cytoskeleton, and conversion of mechanical signals into transcriptional programs via mechanosensitive co-transcription factors, such as YAP, TAZ, and MRTF. We further elaborate how prolonged mechanical stress can create persistent myofibroblast memory by direct mechanotransduction to the nucleus that can evoke lasting epigenetic modifications at the DNA level, such as histone methylation and acetylation. We conclude by projecting how cell culture mechanics can be modulated to generate MSCs, which epigenetically protected against myofibroblast activation and transport desired regeneration potential to the recipient tissue environment in clinical therapies.

Inhibition of Integrin-Associated Kinases FAK and ILK on the In Vitro Model of Skin Wound Healing

Dermal fibroblasts are essential cells of skin tissue responsible for its normal functioning. In skin wounds, the differentiation of resident fibroblasts into myofibroblasts occurs, which is accompanied by the rearrangement of actin cytoskeleton with the expression of alpha-smooth muscle actin. This transformation is a prerequisite for a successful wound healing. At the same time, different studies indicate that extracellular matrix may be involved in regulation of this process. Since the connection between cells and matrix is provided by transmembrane integrin receptors, this work was aimed at studying the dynamics of signaling pathways associated with integrins on an in vitro model of wound healing using human skin fibroblasts. It was shown that the healing of simulated wound was accompanied by a change in the level of integrins as well as integrin-associated kinases ILK (integrin-linked kinase) and FAK (focal adhesion kinase). Pharmacological inhibition of ILK and FAK caused the suppression of p38 and Akt which proteins are involved in regulation of the actin cytoskeleton. Moreover, it resulted in an inefficient wound closure in vitro. The results of this study support the involvement of integrin-associated kinases in regulation of fibroblast-to-myofibroblast transition during wound healing.

Fibroblast and myofibroblast activation in normal tissue repair and fibrosis

The term 'fibroblast' often serves as a catch-all for a diverse array of mesenchymal cells, including perivascular cells, stromal progenitor cells and bona fide fibroblasts. Although phenotypically similar, these subpopulations are functionally distinct, maintaining tissue integrity and serving as local progenitor reservoirs. In response to tissue injury, these cells undergo a dynamic fibroblast-myofibroblast transition, marked by extracellular matrix secretion and contraction of actomyosin-based stress fibres. Importantly, whereas transient activation into myofibroblasts aids in tissue repair, persistent activation triggers pathological fibrosis. In this Review, we discuss the roles of mechanical cues, such as tissue stiffness and strain, alongside cell signalling pathways and extracellular matrix ligands in modulating myofibroblast activation and survival. We also highlight the role of epigenetic modifications and myofibroblast memory in physiological and pathological processes. Finally, we discuss potential strategies for therapeutically interfering with these factors and the associated signal transduction pathways to improve the outcome of dysregulated healing.

Gamma-Secretase Inhibitors Downregulate the Profibrotic NOTCH Signaling Pathway in Recessive Dystrophic Epidermolysis Bullosa

Recessive dystrophic epidermolysis bullosa (RDEB) is a rare skin fragility disorder caused by mutations in COL7A1. RDEB is hallmarked by trauma-induced unremitting blistering, chronic wounds with inflammation, and progressive fibrosis, leading to severe disease complications. There is currently no cure for RDEB-associated fibrosis. Our previous studies and increasing evidence highlighted the profibrotic role of NOTCH pathway in different skin disorders, including RDEB. In this study, we further investigated the role of NOTCH signaling in RDEB pathogenesis and explored the effects of its inhibition by γ-secretase inhibitors DAPT and PF-03084014 (nirogacestat). Our analyses demonstrated that JAG1 and cleaved NOTCH1 are upregulated in primary RDEB fibroblasts (ie, RDEB-derived fibroblasts) compared with controls, and their protein levels are further increased by TGF-β1 stimulation. Functional assays unveiled the involvement of JAG1/NOTCH1 axis in RDEB fibrosis and demonstrated that its blockade counteracts a variety of fibrotic traits. In particular, RDEB-derived fibroblasts treated with PF-03084014 showed (i) a significant reduction of contractility, (ii) a diminished secretion of TGF-β1 and collagens, and (iii) the downregulation of several fibrotic proteins. Although less marked than PF-03084014-treated cells, RDEB-derived fibroblasts exhibited a reduction of fibrotic traits also upon DAPT treatment. This study provides potential therapeutic strategies to antagonize RDEB fibrosis onset and progression.

Alveolar fibroblast lineage orchestrates lung inflammation and fibrosis

Fibroblasts are present throughout the body and function to maintain tissue homeostasis. Recent studies have identified diverse fibroblast subsets in healthy and injured tissues1,2, but the origins and functional roles of injury-induced fibroblast lineages remain unclear. Here we show that lung-specialized alveolar fibroblasts take on multiple molecular states with distinct roles in facilitating responses to fibrotic lung injury. We generate a genetic tool that uniquely targets alveolar fibroblasts to demonstrate their role in providing niches for alveolar stem cells in homeostasis and show that loss of this niche leads to exaggerated responses to acute lung injury. Lineage tracing identifies alveolar fibroblasts as the dominant origin for multiple emergent fibroblast subsets sequentially driven by inflammatory and pro-fibrotic signals after injury. We identify similar, but not completely identical, fibroblast lineages in human pulmonary fibrosis. TGFβ negatively regulates an inflammatory fibroblast subset that emerges early after injury and stimulates the differentiation into fibrotic fibroblasts to elicit intra-alveolar fibrosis. Blocking the induction of fibrotic fibroblasts in the alveolar fibroblast lineage abrogates fibrosis but exacerbates lung inflammation. These results demonstrate the multifaceted roles of the alveolar fibroblast lineage in maintaining normal alveolar homeostasis and orchestrating sequential responses to lung injury.

Exosomes from adipose-derived mesenchymal stem cell improve diabetic wound healing and inhibit fibrosis via miR-128-1-5p/TGF-β1/Smad axis

OBJECTIVE

Difficult-to-heal wound is a prevalent and significant complication of diabetes, characterized by impaired functionality of epithelial cells such as fibroblasts. This study aims to investigate the potential mechanism of ADSC-Exos promoting diabetic wound healing by regulating fibroblast function.

MATERIALS AND METHODS

ADSC-Exos were confirmed through TEM, NTA, and Western Blot techniques. The study conducted on rat skin fibroblasts (RSFs) exposed to 33 mmol/L glucose in vitro. We used cck-8, EDU, transwell, and scratch assays to verify the proliferation and migration of RSFs. Furthermore, levels of TGF-β1 and α-SMA proteins were determined by immunofluorescence and Western Blot. RSFs were transfected with miR-128-1-5p mimics and inhibitors, followed by quantification of TGF-β1, α-SMA, Col I and Smad2/3 protein levels using Western Blot. In vivo, the effects of ADSC-Exos on diabetic wounds were assessed using digital imaging, histological staining, as well as Western Blot analysis.

RESULTS

In vitro, ADSC-Exos significantly enhanced proliferation and migration of RSFs while reducing the expression of TGF-β1 and α-SMA. In vivo, ADSC-Exos effectively promoted diabetic wound healing and mitigated scar fibrosis. Additionally, ADSC-Exos exhibited elevated levels of miR-128-1-5p, which targets TGF-β1, resulting in a notable reduction in TGF-β1, α-SMA, Col I and smad2/3 phosphorylation in RSFs.

CONCLUSION

In conclusion, our results demonstrated that ADSC-Exos promoted diabetic wound healing, and inhibited skin fibrosis by regulating miR-128-1-5p/TGF-β1/Smad signaling pathway, which provides a promising innovative treatment for diabetic wound healing.

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.

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.

O-GlcNAcylation controls pro-fibrotic transcriptional regulatory signaling in myofibroblasts

Tissue injury causes activation of mesenchymal lineage cells into wound-repairing myofibroblasts (MFs), whose uncontrolled activity ultimately leads to fibrosis. Although this process is triggered by deep metabolic and transcriptional reprogramming, functional links between these two key events are not yet understood. Here, we report that the metabolic sensor post-translational modification O-linked β-D-N-acetylglucosaminylation (O-GlcNAcylation) is increased and required for myofibroblastic activation. Inhibition of protein O-GlcNAcylation impairs archetypal myofibloblast cellular activities including extracellular matrix gene expression and collagen secretion/deposition as defined in vitro and using ex vivo and in vivo murine liver injury models. Mechanistically, a multi-omics approach combining proteomic, epigenomic, and transcriptomic data mining revealed that O-GlcNAcylation controls the MF transcriptional program by targeting the transcription factors Basonuclin 2 (BNC2) and TEA domain transcription factor 4 (TEAD4) together with the Yes-associated protein 1 (YAP1) co-activator. Indeed, inhibition of protein O-GlcNAcylation impedes their stability leading to decreased functionality of the BNC2/TEAD4/YAP1 complex towards promoting activation of the MF transcriptional regulatory landscape. We found that this involves O-GlcNAcylation of BNC2 at Thr455 and Ser490 and of TEAD4 at Ser69 and Ser99. Altogether, this study unravels protein O-GlcNAcylation as a key determinant of myofibroblastic activation and identifies its inhibition as an avenue to intervene with fibrogenic processes.

Dynamic reporters for probing real-time activation of human fibroblasts from single cells to populations

Activation of fibroblasts is pivotal for wound healing; however, persistent activation leads to maladaptive processes and is a hallmark of fibrosis, where disease mechanisms are only partially understood. Human in vitro model systems complement in vivo animal models for both hypothesis testing and drug evaluation to improve the identification of therapeutics relevant to human disease. Despite advances, a challenge remains in understanding the dynamics of human fibroblast responses to complex microenvironment stimuli, motivating the need for more advanced tools to investigate fibrotic mechanisms. This work established approaches for assessing the temporal dynamics of these responses using genetically encoded fluorescent reporters of alpha smooth muscle actin expression, an indicator of fibroblast activation. Specifically, we created a toolset of human lung fibroblast reporter cell lines from different origins (male, female; healthy, idiopathic pulmonary fibrosis) and used three different versions of the reporter with the fluorescent protein modified to exhibit different temporal stabilities, providing temporal resolution of protein expression processes over a range of timescales. Using this toolset, we demonstrated that reporters provide insight into population shifts in response to both mechanical and biochemical cues that are not detectable by traditional end point assessments with differential responses based on cell origin. Furthermore, individual cells can also be tracked over time, with opportunities for comparison to complementary end point measurements. The establishment of this reporter toolset enables dynamic cell investigations that can be translated into more complex synthetic culture environments for elucidating disease mechanisms and evaluating therapeutics for lung fibrosis and other complex biological processes more broadly.