Epithelial-mesenchymal transition in tissue repair and fibrosis

Hidradenitis Suppurativa Tunnels: Unveiling a Unique Disease Entity

Hidradenitis suppurativa tunnel structures lined with epithelium within the dermis are unique features of advanced disease stages that significantly impair patients' QOL. The presence of hidradenitis suppurativa tunnels is associated with a decreased likelihood of achieving a clinical response, even when receiving biological therapy. The cellular and molecular mechanisms underlying tunnel formation and pathology are only partially understood, which hampers the development of more effective targeted therapies. Tunnels create a unique microenvironment that drives a vicious cycle of hidradenitis suppurativa inflammation, with tunnel keratinocytes exhibiting an activated phenotype characterized by distinct gene expression signatures. In this review, we summarize the current literature and discuss aspects of the pathophysiology of tunnels, including the role of hair follicle epidermal stem cells in tunnel formation, potential role of fibroblast-mediated epithelial-mesenchymal transition, role of dermal papilla fibroblasts, and aberrant proinflammatory repair response contributing to the observed fibrosis and scarring. Finally, tunnel structures are characterized by unique microbial dysbiosis and an overabundance of Gram-negative anaerobes that are not targeted by current therapeutics. In addition to outlining the possible mechanisms of tunnel formation, we provide perspectives on the translation of current knowledge into more effective treatment approaches for patients with hidradenitis suppurativa tunnels.

A Boolean network model of hypoxia, mechanosensing and TGF-β signaling captures the role of phenotypic plasticity and mutations in tumor metastasis

The tumor microenvironment aids cancer progression by promoting several cancer hallmarks, independent of cancer-related mutations. Biophysical properties of this environment, such as the stiffness of the matrix cells adhere to and local cell density, impact proliferation, apoptosis, and the epithelial to mesenchymal transition (EMT). The latter is a rate-limiting step for invasion and metastasis, enhanced in hypoxic tumor environments but hindered by soft matrices and/or high cell densities. As these influences are often studied in isolation, the crosstalk between hypoxia, biomechanical signals, and the classic EMT driver TGF-β is not well mapped, limiting our ability to predict and anticipate cancer cell behaviors in changing tumor environments. To address this, we built a Boolean regulatory network model that integrates hypoxic signaling with a mechanosensitive model of EMT, which includes the EMT-promoting crosstalk of mitogens and biomechanical signals, cell cycle control, and apoptosis. Our model reproduces the requirement of Hif-1α for proliferation, the anti-proliferative effects of strong Hif-1α stabilization during hypoxia, hypoxic protection from anoikis, and hypoxia-driven mechanosensitive EMT. We offer experimentally testable predictions about the effect of VHL loss on cancer hallmarks, with or without secondary oncogene activation. Taken together, our model serves as a predictive framework to synthesize the signaling responses associated with tumor progression and metastasis in healthy vs. mutant cells. Our single-cell model is a key step towards more extensive regulatory network models that cover damage-response and senescence, integrating most cell-autonomous cancer hallmarks into a single model that can, in turn, control the behavior of in silico cells within a tissue model of epithelial homeostasis and carcinoma.

Adhesive and Antioxidant Hydrogel with Glucose/ROS Dual-Responsive Drug Release for Diabetic Oral Mucosal Wound Healing

Diabetes mellitus is a global health threat, with chronic wounds, including oral mucosal wounds, being a severe complication. These wounds are characterized by delayed healing and increased inflammation due to hyperglycemia, affecting patients' quality of life. Current treatments for oral mucosal wounds cannot offer sustained management of these injuries in diabetic patients. Here, a glucose/ROS dual-responsive hydrogel incorporating sitagliptin was developed for the treatment of diabetic oral mucosal wounds. After chemical modification of tetra-armed poly(ethylene glycol) succinimidyl glutarate (tetra-PEG-SG) by dopamine (DA) and tetra-armed poly(ethylene glycol) amine (tetra-PEG-NH2) by phenylboronic acid (PBA), the resulting hydrogel was capable of rapid gelation, robust tissue adhesion, self-healing, antioxidant capacity, and dual response to glucose and reactive oxygen species (ROS), enabling the feasible injection and stable adherence in the moist oral environment while ensuring sustained therapeutic sitagliptin release. In vivo experiments on oral mucosal defects in diabetic mice revealed that the sitagliptin-loaded hydrogel could effectively reduce inflammation and promote wound healing. Collectively, this finding identifies a potential wound dressing as a therapeutic strategy for diabetic oral mucosal wounds.

Matrix metalloproteinase-driven epithelial-mesenchymal transition: implications in health and disease

Epithelial-mesenchymal transition (EMT) is a process in which epithelial cells, defined by apical-basal polarity and tight intercellular junctions, acquire migratory and invasive properties characteristic of mesenchymal cells. Under normal conditions, EMT directs essential morphogenetic events in embryogenesis and supports tissue repair. When dysregulated, EMT contributes to pathological processes such as organ fibrosis, chronic inflammation, and cancer progression and metastasis. Matrix metalloproteinases (MMPs)-a family of zinc-dependent proteases that degrade structural components of the extracellular matrix-sit at the nexus of this transition by dismantling basement membranes, activating pro-EMT signaling pathways, and cleaving adhesion molecules. When normally regulated, MMPs promote balanced ECM turnover and support the cyclical remodeling necessary for proper development, wound healing, and tissue homeostasis. When abnormally regulated, MMPs drive excessive ECM turnover, thereby promoting EMT-related pathologies, including tumor progression and fibrotic disease. This review provides an integrated overview of the molecular mechanisms by which MMPs both initiate and sustain EMT under physiological and disease conditions. It discusses how MMPs can potentiate EMT through TGF-β and Wnt/β-catenin signaling, disrupt cell-cell junction proteins, and potentiate the action of hypoxia-inducible factors in the tumor microenvironment. It discusses how these pathologic processes remodel tissues during fibrosis, and fuel cancer cell invasion, metastasis, and resistance to therapy. Finally, the review explores emerging therapeutic strategies that selectively target MMPs and EMT, ranging from CRISPR/Cas-mediated interventions to engineered tissue inhibitors of metalloproteinases (TIMPs), and demonstrates how such approaches may suppress pathological EMT without compromising its indispensable roles in normal biology.

Cyanidin-3-glucoside upregulated NDRG2 through the PI3K/AKT pathway to alleviate EMT and ECM in renal fibrosis

Renal fibrosis is a critical progression of chronic kidney disease, and epithelial-to-mesenchymal transition (EMT) and extracellular matrix(ECM) deposition are crucial pathologic change of renal fibrosis, which still lacks of effective treatment. In this study, it was found that cyanidin-3-O-glucoside (C3G) could inhibit EMT and ECM activated by unilateral ureteral obstruction (UUO) and transforming growth factor-β1 (TGF-β1) stimulation. Moreover, N-Myc downstream-regulated gene 2(NDRG2), which involved in the progression of renal fibrosis, was down-regulated in vivo and in vitro model. However, C3G pretreatment could reverse the reductive expression of NDRG2. Furthermore, we found that the combined treatment of C3G and si-NDRG2 could reverse the decreased EMT and ECM, which induced by C3G treatment only. And the activation of Phosphatidylinositol 3-kinase (PI3K)/ Protein Kinase B (AKT) pathway significantly enhanced EMT and ECM, which was decreased by C3G treatment only in TGF-β1 induced Human Kidney 2 (HK-2) cells. In conclusion, our results demonstrated that C3G alleviated EMT and ECM by elevating NDRG2 expression through the PI3K/AKT pathway, indicating that C3G could be a potential treatment against renal fibrosis.

A human histidyl-tRNA synthetase splice variant therapeutic targets NRP2 to resolve lung inflammation and fibrosis

Interstitial lung disease (ILD) consists of a group of immune-mediated disorders that can cause inflammation and progressive fibrosis of the lungs, representing an area of unmet medical need given the lack of disease-modifying therapies and toxicities associated with current treatment options. Tissue-specific splice variants (SVs) of human aminoacyl-tRNA synthetases (aaRSs) are catalytic nulls thought to confer regulatory functions. One example from human histidyl-tRNA synthetase (HARS), termed HARSWHEP because the splicing event resulted in a protein encompassing the WHEP-TRS domain of HARS (a structurally conserved domain found in multiple aaRSs), is enriched in human lung and up-regulated by inflammatory cytokines in lung and immune cells. Structural analysis of HARSWHEP confirmed a well-organized helix-turn-helix motif. This motif bound specifically and selectively to neuropilin-2 (NRP2), a receptor expressed by myeloid cells in active sites of inflammation, to inhibit expression of proinflammatory receptors and cytokines and to down-regulate inflammatory pathways in primary human macrophages. In animal models of lung injury and ILD, including bleomycin treatment, silicosis, sarcoidosis, chronic hypersensitivity pneumonitis, systemic sclerosis, and rheumatoid arthritis-ILD, HARSWHEP reduced lung inflammation, immune cell infiltration, and fibrosis. In patients with sarcoidosis, efzofitimod treatment resulted in down-regulation of gene expression for inflammatory pathways in peripheral immune cells and stabilization of inflammatory biomarkers in serum after steroid tapering. We demonstrate the immunomodulatory activity of HARSWHEP and present preclinical data supporting ongoing clinical development of the biologic efzofitimod based on HARSWHEP in ILD.

Radiation therapy-induced normal tissue damage: involvement of EMT pathways and role of FLASH-RT in reducing toxicities

Radiation therapy (RT) is fundamental to the fight against cancer because of its exceptional ability to target and destroy cancer cells. However, conventional radiation therapy can significantly affect the adjacent normal tissues, leading to fibrosis, inflammation, and decreased organ function. This tissue damage not only reduces the quality of life but also prevents the total elimination of cancer. The transformation of epithelial cells into mesenchymal-like cells, termed epithelial-mesenchymal transition (EMT), is essential for processes such as fibrosis, embryogenesis, and wound healing. Conventional radiation therapy increases the asymmetric activation of fibrotic and inflammatory pathways, and the resulting chronic fibrotic changes and organ dysfunction are linked to radiation-induced epithelial-mesenchymal transition. Recent advances in radiation therapy, namely flash radiation therapy (FLASH-RT), have the potential to widen the therapeutic index. Radiation delivered by FLASH-RT at very high dose rates (exceeding 40 Gy/s) can protect normal tissue from radiation-induced damage, a phenomenon referred to as the "FLASH effect". Preclinical studies have demonstrated that FLASH-RT successfully inhibits processes associated with fibrosis and epithelial-mesenchymal transition, mitigates damage to normal tissue, and enhances regeneration. Three distinct types of EMT have been identified: type-1, associated with embryogenesis; Type-2, associated with injury potential; and type-3, related with cancer spread. The regulation of EMT via pathways, including TGF-β/SMAD, WNT/β-catenin, and NF-κB, is essential for radiation-induced tissue remodelling. This study examined radiation-induced EMT, TGF-β activity, multiple signalling pathways in fibrosis, and the potential of FLASH-RT to reduce tissue damage. FLASH-RT is a novel approach to treat chronic tissue injury and fibrosis post-irradiation by maintaining epithelial properties and regulating mesenchymal markers including vimentin and N-cadherin. Understanding these pathways will facilitate the development of future therapies that can alleviate fibrosis, improve the efficacy of cancer therapy, and improve the quality of life of patients.

miR-200c inhibition and catalase accelerate diabetic wound healing

BACKGROUND

Reactive oxygen species (ROS) are increased in diabetic conditions and play a causal role in diabetic foot ulcers (DFU). We previously showed that ROS up-regulate miR-200c expression, that in turns causes apoptosis, senescence, ROS upregulation and nitric oxide decrease, leading to endothelial disfunction.

METHODS

The aim of this study is to dissect miR-200c role in DFU and to explore the potential role of anti-miR-200c and antioxidant catalase (CAT) in promoting wound healing (WH). miR-200c inhibition and CAT treatment were performed either in immortalized keratinocytes (HaCaT) or in primary fibroblasts (FBs) and keratinocytes (KCs) deriving from diabetic patients (pts) undergoing amputations. Primary cells deriving from pts undergoing saphenectomies were used as controls. The miR-200c blockade was performed either via lentiviral particles bearing an anti-miR-200c sequence or locked nucleic acid (LNA) anti-miR-200c oligos. Equine CAT was administered on cell medium. The WH assay was performed in vivo on diabetic (db/db) mice by a topical treatment with CAT and LNA anti-miR-200c on wounds dissolved in a Pluronic gel mixture, administered every three days.

RESULTS

We found that miR-200c levels were increased by different stimuli known to induce ROS, such as ultraviolet radiation (UV), hydrogen peroxide (H2O2), and high glucose in HaCaT. miR-200c was also upregulated in skin biopsies, in FBs and KCs isolated from pts with DFU vs controls. Forced miR-200c expression induced ROS in both FBs and KCs, and CAT reduced it. miR-200c inhibition improved WH in HaCaT, both under basal conditions and after UV and H2O2 treatment, and the simultaneous treatment with CAT accelerated it. miR-200c inhibition accelerated WH in KCs of DFU pts, increasing its protein targets: sirtuin 1 (SIRT1), the transcription factors FOXO1 and ZEB1 and decreasing p66Shc phosphorylation at Ser-36, that is induced by ROS, and the co-treatment with CAT showed synergistic effects in reducing ROS and cytotoxicity. Interestingly, CAT treatment decreased miR-200c expression in FBs and KCs of DFU pts. Topical administration of anti-miR-200c and CAT in a WH model of diabetic mice accelerated closure.

CONCLUSIONS

Anti-miR-200c and CAT could be considered a novel treatment for DFU and, possibly, for other types of non-diabetic skin ulcers.

Growth factors IGF-1 and KGF and adipose-derived stem cells promote migration and viability of primary human keratinocytes in an in vitro wound model

Introduction

In the field of plastic surgery, epidermal transplantation is a potential treatment for chronic wounds that results in only minor donor site morbidity. Improving the regenerative capacities of epidermal grafts or single-cell suspensions and therefore accelerating healing processes would be of significant interest.

Methods

In the present study, we analyzed the effects of growth factors and adipose-derived stem cells (ADSCs) on keratinocyte properties. For optimum translation into the clinical setting, primary human keratinocytes and patient-matched ADSCs were isolated and used in an in vitro wound model.

Results

The keratinocyte migration and viability increased after treatment with the growth factors insulin-like growth factor 1 (IGF-1) and keratinocyte growth factor (KGF). A similar effect was observed with the use of a concentrated ADSC-conditioned medium (ADSC-CM). It was further possible to isolate the keratinocytes in a xenogen-free medium, which is essential for clinical translation. Importantly, a patient-dependent influence on the effects of the growth factors and ADSC-CM was observed.

Discussion

This study provides potential for the improvement of epidermal transplantation in the treatment of chronic wounds using xenogen-free isolated and cultivated keratinocytes, growth factors, and ADSC. Translating these results into clinical application may help accelerate wound healing and shorten the time until patients can return to everyday life.

Yiqi Juanshen decoction alleviates renal interstitial fibrosis by targeting the LOXL2/PI3K/AKT pathway to suppress EMT and inflammation

Chronic kidney disease (CKD) is a major health concern, with renal interstitial fibrosis (RIF) as a key feature. Effective management of RIF is crucial for treating CKD. Yiqi Juanshen decoction (YQJSD), as traditional Chinese medicine, has shown promising results in CKD treatment. This study evaluates YQJSD's effectiveness in ameliorating RIF and explores the underlying molecular mechanisms using the unilateral ureteral obstruction (UUO) model. YQJSD has been shown to effectively reduce serum creatinine and blood urea nitrogen levels, decrease extracellular matrix deposition, and down-regulate the expression of α-SMA, COL4α1, Fibronectin (FN). Mechanistically, YQJSD exerts its effects by modulating multiple pathways: it inhibits the NF-κB signaling pathway, inhibiting the expression of pro-inflammatory cytokines like NF-κB1, IL-1β, TNF-α, and CCR1. Simultaneously, YQJSD suppresses the epithelial-mesenchymal transition (EMT) by downregulating the expression of Snail1, Vimentin, Twist1, and FSP1, while increasing E-cadherin expression. Moreover, YQJSD can regulate the PI3K/AKT signaling pathway by decreasing the expression of LOXL2 and PIK3R1, along with p-AKT1/2/3. This modulation of the LOXL2/PI3K/AKT pathway contributes to the inhibition of both EMT and inflammation, highlighting a critical role in the therapeutic intervention against RIF. These findings suggest that YQJSD may serve as a promising therapeutic management of RIF in CKD patients.

Recent advances in the role of neuroregulation in skin wound healing

Neuroregulation during skin wound healing involves complex interactions between the nervous system and intricate tissue repair processes. The skin, the largest organ, depends on a complex system of nerves to manage responses to injury. Recent research has emphasized the crucial role of neuroregulation in maximizing wound healing outcomes. Recently, researchers have also explained the interactive contact between the peripheral nervous system and skin cells during the different phases of wound healing. Neurotransmitters and neuropeptides, once observed as simple signalling molecules, have since been recognized as effective regulators of inflammation, angiogenesis, and cell proliferation. The significance of skin innervation and neuromodulators is underscored by the delayed wound healing observed in patients with diabetes and the regenerative capabilities of foetal skin. Foetal skin regeneration is influenced by the neuroregulatory environment, immature immune system, abundant growth factors, and increased pluripotency of cells. Foetal skin cells exhibit greater flexibility and specialized cell types, and the extracellular matrix composition promotes regeneration. The extracellular matrix composition of foetal skin promotes regeneration, making it more capable than adult skin because neuroregulatory signals affect skin regeneration. The understanding of these systems can facilitate the development of therapeutic strategies to alter the nerve supply to the skin to enhance the process of wound healing. Neuroregulation is being explored as a potential therapeutic strategy for enhancing skin wound repair. Bioelectronic strategies and neuromodulation techniques can manipulate neural signalling, optimize the neuroimmune axis, and modulate inflammation. This review describes the function of skin innervation in wound healing, emphasizing the importance of neuropeptides released by sensory and autonomic nerve fibres. This article discusses significant discoveries related to neuroregulation and its impact on skin wound healing.

Novel drug delivery systems for hirudin-based product development and clinical applications

Hirudin, a natural biological polypeptide macromolecule secreted by the salivary glands of medicinal leech, is a specific thrombin inhibitor with multiple favourable bioactivities, including anti-coagulation, anti-fibrotic, and anti-tumour. Despite several anticoagulants have been widely applied in clinic, hirudin shows advantages in reducing the incidence of bleeding side effects by virtue of its high specificity in binding to thrombin. As a result, hirudin has been tested in clinical practice to prevent and treat several complex diseases. However, the application of this polypeptide macromolecule is compromised by its low bioavailability and bioactivity due to poor serum stability and susceptibility to protease degradation in vivo. To overcome these drawbacks, several studies have proposed novel drug delivery systems (NDDSs) to prevent the degradation and increase the targeting efficiency of hirudin. This systematic review summarises the clinical research on hirudin, including its classification and bioactivities, and highlights the opportunities and challenges in the clinical use of hirudin. The NDDSs designed to enhance the bioavailability and bioactivity of hirudin are discussed to explore its application in the treatment of related diseases. This review may considerably contribute to the advancement of delivery science and technology, particularly in the context of polypeptide-based therapeutics.

Novel Therapeutic Strategies Targeting Fibroblasts to Improve Heart Disease

Cardiac fibrosis represents the terminal pathological manifestation of various heart diseases, with the formation of fibroblasts playing a pivotal role in this process. Consequently, targeting the formation and function of fibroblasts holds significant potential for improving outcomes in heart disease. Recent research reveals the considerable potential of fibroblasts in ameliorating cardiac conditions, demonstrating different functional characteristics at various time points and spatial locations. Therefore, precise modulation of fibroblast activity may offer an effective approach for treating cardiac fibrosis and achieving targeted therapeutic outcomes. In this review, we focus on the fate and inhibition of fibroblasts, analyze their dynamic changes in cardiac diseases, and propose a framework for identifying markers of fibroblast activation mechanisms and selecting optimal time windows for therapeutic intervention. By synthesizing research findings in these areas, we aim to provide new strategies and directions for the precise treatment of fibroblasts in cardiac diseases.

Topography-Mediated Induction of Epithelial Mesenchymal Transition via Alumina Textiles for Potential Wound Healing Applications

Substrate topography is vital in determining cell growth and fate of cellular behavior. Although current in vitro studies of the underlying cellular signaling pathways mostly rely on their induction by specific growth factors or chemicals, the influence of substrate topography on specific changes in cells has been explored less often. This study explores the impact of substrate topography, specifically the tricot knit microfibrous structure of alumina textiles, on cell behavior, focusing on fibroblasts and keratinocytes for potential wound healing applications. The textiles, studied for the first time as in vitro substrates, demonstrated support for keratinocyte adhesion, leading to alterations in cell morphology and the expression of E-cadherin and fibronectin. These topography-induced changes resembled the epithelial-to-mesenchymal transition (EMT), crucial for wound healing, and were specific to keratinocytes and absent in identically treated fibroblasts. Biochemically induced EMT in keratinocytes cultured on flat alumina substrates mirrored the changes seen with alumina textiles alone, suggesting the tricot knit microfibrous topography could serve as an in vitro model system to induce EMT-like mechanisms. These results enhance our understanding of how substrate topography influences EMT-related processes in wound healing, paving the way for further evaluation of microfibrous alumina textiles as innovative wound dressings.

Broadly Accessible 3D In Vitro Skin Model as a Comprehensive Platform for Antibacterial Therapy Screening

Skin infections are currently a worldwide emergency as antibiotic-resistant bacteria are spreading, leading to the ineffectiveness of most antibiotics and antibacterial strategies. Consequently, there is an urgency of developing and testing innovative antibacterial therapies. As traditional 2D cell culture and planktonic bacteria culture can be obsolete due to their incapability of resembling the complex infection environment, 3D in vitro skin models can be a powerful tool to test and validate therapies. In this article, a 3D in vitro epidermis-dermis skin model has been developed and biofabricated to be broadly available, reaching a balance between the simplicity and reproducibility of the model and its complexity in terms of wound, infection, and treatment response. The results are really promising, as the skin model developed a comprehensive physical barrier. To further investigate the skin model, controlled wounding, infection, and antibiotic treatments were performed. The results were remarkable: Not only was the unwounded epidermal barrier able to partially stop the bacterial proliferation, but the entire system reacted to both wound and infection in a complex and complete way. Extracellular matrix deposition and remodeling, inflammatory response, antimicrobial peptide production, and change in cellular behaviors, from epithelial to mesenchymal and from fibroblasts to myofibroblasts, were witnessed, with different extents depending on the bacterial strain. In addition, the inflammatory response to the antibiotic administration was opposite for the two bacterial infections, probably revealing the release of inflammatory endotoxins during Escherichia coli death. In conclusion, the presented 3D in vitro skin model has all the characteristics to be a future landmark as a platform for antibacterial strategy therapy testing.

Slit1 Promotes Hypertrophic Scar Formation Through the TGF-β Signaling Pathway

Background and objectives: Slit1 is a secreted protein that is closely related to cell movement and adhesion. Few studies related to fibrosis exist, and the preponderance of current research is confined to the proliferation and differentiation of neural systems. Hypertrophic scars (HTSs) are delineated by an overproduction of the extracellular matrix (ECM) by activated fibroblasts, leading to anomalous fibrosis, which is a severe sequela of burns. However, the functionality of Slit1 in HTS formation remains unknown. We aimed to investigate whether Slit1 regulates fibroblasts through a fibrosis-related mechanism derived from post-burn HTS tissues and normal patient tissues. Methods: Human normal fibroblasts (HNFs) and hypertrophic scar fibroblasts (HTSFs) were extracted from normal skin and post-burn HTS tissues, with settings grouped according to the patient of origin. Cell proliferation was evaluated using a CellTiter-Glo Luminescent Cell Viability Assay Kit. Cell migration experiments were carried out using a μ-Dish insert system. Protein and mRNA expression levels were quantified by Western blot and quantitative real-time polymerase chain reaction. Results: We found increased expressions of Slit1 in HTS tissues and HTSFs compared to normal tissues and HNFs. The treatment of human recombinant Slit1 protein (rSlit1) within HNFs promoted cell proliferation and differentiation, leading to an upregulation in ECM components such as α-SMA, type I and III collagen, and fibronectin. The treatment of rSlit1 in HNFs facilitated cell migration, concurrent with enhanced levels of N-cadherin and vimentin, and a diminished expression of E-cadherin. Treatment with rSlit1 resulted in the phosphorylation of SMAD pathway proteins, including SMAD2, SMAD3, and SMAD1/5/8, and non-SMAD pathway proteins, including TAK1, JNK1, ERK1/2, and p38, in HNFs. Conclusions: Exogenous Slit1 potentiates the epithelial-mesenchymal transition and upregulates SMAD and non-SMAD signaling pathways in HNFs, leading to the development of HTS, suggesting that Slit1 is a promising new target for the treatment of post-burn HTS.

Endoplasmic reticulum stress induces renal fibrosis in high‑fat diet mice via the TGF‑β/SMAD pathway

The aim of the present study was to investigate the role and mechanism of endoplasmic reticulum stress (ERS) in kidney injury caused by high‑fat diet (HFD). An obese mouse model was established via HFD feeding and intervention was performed by intraperitoneal injection of the ERS inhibitor salubrinal (Sal). Changes in the body and kidney weight and serum biochemical indices of the mice were determined. Hematoxylin and eosin and Masson staining were used to observe the pathological changes of renal tissues. Reverse transcription‑quantitative PCR and western blotting were used to observe the expression of ERS‑related proteins and TGF‑β/SMAD pathway‑related proteins. Immunohistochemistry was employed to explore the distribution of these proteins. Compared with those in the control group, the weight gain, lipid metabolism disorders and deterioration of renal function in the model group were greater. Malondialdehyde was elevated and superoxide dismutase was decreased in renal tissues. The mRNA and protein levels of TGF‑β1, SMAD2/3, α‑smooth muscle actin, collagen I, glucose‑regulated protein 78 and C/EBP‑homologous protein were markedly elevated, whereas SMAD7 was markedly decreased. Sal markedly inhibited the aforementioned effects. This investigation revealed a link between ERS and renal injury caused by HFD. ERS in HFD‑fed mice triggers renal fibrosis through the TGF‑β/SMAD pathway.

Sulfated Galactan Derivative from Gracilaria fisheri Improves Histopathology and Alters Wound Healing-Related Proteins in the Skin of Excision Rats

BACKGROUND

The biological activities of sulfated polysaccharides (SP) are well-documented, especially regarding wound healing. Sulfated galactan (SG), a type of SP extracted from the red seaweed Gracilaria fisheri, has been identified as having multiple therapeutic properties related to its wound healing capacity. Recent research indicates that degraded SG (DSG) from G. fisheri, when combined with octanoyl ester (DSGO), can improve wound healing in fibroblasts. However, the effectiveness of natural products in clinical settings often differs from in vitro results. This study aimed to develop and evaluate ointments containing DSG and DSGO for skin repair in an animal model.

METHODS

Twenty-four Wistar rats were divided into four groups: (1) normal control, (2) ointment control, (3) DSG ointment, and (4) DSGO ointment. After inducing full-thickness excision wounds, these ointments were applied to the wounds. Wound contraction rate, histopathology, and protein related wound healing expression were then elucidated.

RESULTS

Our findings showed that both DSG and DSGO ointments significantly enhanced wound closure compared to the control groups. Histopathological and biochemical analyses indicated increased extracellular matrix production and fibroblasts, marked by improved fibroblast activity, neovascularization, and collagen deposition. Furthermore, immunohistochemistry and immunoblot analysis revealed that the ointments altered the expression of Ki67, α-smooth muscle actin (α-SMA), E-cadherin, vimentin, collagen, and components of the Smad signaling pathway, all of which are crucial for wound healing. The results also suggested that the DSGO ointment was marginally more effective in promoting wound healing in this model.

CONCLUSIONS

These results indicate that ointment supplemented with DSG and DSGO have the potential to enhance skin repair by improving histopathology and altering wound healing-related proteins.

OSGIN1 regulates PM2.5-induced fibrosis via mediating autophagy in an in vitro model of COPD

Fine particulate matter (PM2.5) has been identified as a significant contributing factor to the exacerbation of chronic obstructive pulmonary disease (COPD). It has been observed that PM2.5 may induce lung fibrosis in COPD, although the precise molecular mechanism behind this remains unclear. In a previous study, we demonstrated that PM2.5 upregulates oxidative stress induced growth inhibitor 1 (OSGIN1), which in turn leads to injury in airway epithelial cells, thereby, suggesting a potential link between PM2.5 exposure and COPD. Based on this, we hypothesized that OSGIN1 plays a role in PM2.5-induced fibrosis in COPD. Human bronchial epithelial cells (HBEs) were treated with cigarette smoke extract (CSE) to construct an in vitro model of COPD. Our findings revealed that PM2.5 increased fibrosis indicators and upregulated OSGIN1 in CSE-stimulated HBEs (CSE-HBEs), and knockdown of OSGIN1 reduced the expression of fibrosis indicators. Through the use of microRNA target prediction software and the Gene Expression Omnibus database, we predicted miRNAs that targeted OSGIN1 in COPD. Subsequently, real-time polymerase chain reaction and western blot analysis confirmed that PM2.5 modulated miR-654-5p to regulate OSGIN1 in CSE-HBEs. Western blot demonstrated that OSGIN1 induced autophagy, thereby exacerbating fibrosis in CSE-HBEs. In summary, our results suggest that PM2.5 upregulates OSGIN1 through inhibiting miR-654-5p, leading to increased autophagy and fibrosis in CSE-HBEs.

TRPV4-A Multifunctional Cellular Sensor Protein with Therapeutic Potential

Transient receptor potential vanilloid (TRPV) channel proteins belong to the superfamily of TRP proteins that form cationic channels in the animal cell membranes. These proteins have various subtype-specific functions, serving, for example, as sensors for pain, pressure, pH, and mechanical extracellular stimuli. The sensing of extracellular cues by TRPV4 triggers Ca2+-influx through the channel, subsequently coordinating numerous intracellular signaling cascades in a spatio-temporal manner. As TRPV channels play such a wide role in various cellular and physiological functions, loss or impaired TRPV protein activity naturally contributes to many pathophysiological processes. This review concentrates on the known functions of TRPV4 sensor proteins and their potential as a therapeutic target.

HHIP's Dynamic Role in Epithelial Wound Healing Reveals a Potential Mechanism of COPD Susceptibility

A genetic variant near HHIP has been consistently identified as associated with increased risk for Chronic Obstructive Pulmonary Disease (COPD), the third leading cause of death worldwide. However HHIP's role in COPD pathogenesis remains elusive. Canonically, HHIP is a negative regulator of the hedgehog pathway and downstream GLI1 and GLI2 activation. The hedgehog pathway plays an important role in wound healing, specifically in activating transcription factors that drive the epithelial mesenchymal transition (EMT), which in its intermediate state (partial EMT) is necessary for the collective movement of cells closing the wound. Herein, we propose a mechanism to explain HHIP's role in faulty epithelial wound healing, which could contribute to the development of emphysema, a key feature of COPD. Using two different Boolean models compiled from the literature, we show dysfunctional HHIP results in a lack of negative feedback on GLI, triggering a full EMT, where cells become mesenchymal and do not properly close the wound. We validate these Boolean models with experimental evidence gathered from published scientific literature. We also experimentally test if low HHIP expression is associated with EMT at the edge of wounds by using a scratch assay in a human lung epithelial cell line. Finally, we show evidence supporting our hypothesis in bulk and single cell RNA-Seq data from different COPD cohorts. Overall, our analyses suggest that aberrant wound healing due to dysfunctional HHIP, combined with chronic epithelial damage through cigarette smoke exposure, may be a primary cause of COPD-associated emphysema.

Carbon monoxide attenuates cellular senescence-mediated pulmonary fibrosis via modulating p53/PAI-1 pathway

PURPOSE

Idiopathic pulmonary fibrosis (IPF) is a fatal progressive condition often requiring lung transplantation. Accelerated senescence of type II alveolar epithelial cells (AECII) plays a crucial role in pulmonary fibrosis progression through the secretion of the senescence-associated secretory phenotype (SASP). Low-dose carbon monoxide (CO) possesses anti-inflammatory, anti-oxidative, and anti-aging properties. This study aims to explore the preventive effects of CO-releasing molecule 2 (CORM2) in a bleomycin-induced pulmonary fibrosis model.

METHODS

We established an pulmonary fibrosis model in C57BL/6J mice and evaluated the impact of CORM2 on fibrosis pathology using Masson's trichrome staining, fluorescence staining, and pulmonary function tests. Fibrogenic marker expression and SASP secretion in tissues and AECII cells were analyzed using qRT-PCR, Western blot, and ELISA assays both in vivo and in vitro. Additionally, we investigated DNA damage and cellular senescence through immunofluorescence and SA-β-gal staining.

RESULTS

CORM2 showed a preventive effect on bleomycin-induced lung fibrosis by improving pulmonary function and reducing the expression of fibrosis-related genes, such as TGF-β, α-SMA, Collagen I/III. CORM2 decreased the DNA damage response by inhibiting γ-H2AX, p53, and p21. We identified PAI-1 as a new target gene that was downregulated by CORM2, and which was associated with cellular senescence and fibrosis. CORM2 effectively inhibited cellular senescence and delayed EMT occurrence in AECII cells.

CONCLUSION

Our study highlights the potential of CORM2 in preventing DNA damage-induced cellular senescence in bleomycin-induced pulmonary fibrosis through modulation of the p53/PAI-1 signaling pathway. These findings underscore the promising prospects of CORM2 in targeting cellular senescence and the p53/PAI-1 pathway as a potential preventive strategy for IPF.

A systematic review of mesenchymal stem cell secretome: Functional annotations, gene clusters and proteomics analyses for bone formation

The regenerative capacity of mesenchymal stem cells (MSCs) is now attributed to their ability to release paracrine factors into the extracellular matrix that boost tissue regeneration, reduce inflammation and encourage healing. Understanding the MSC secretome is crucial for shifting the prototypic conventional cell-based therapies to cell-free regenerative treatments. This systematic review aimed to analyse the functional annotations of the secretome of human adult adipose tissue and bone marrow MSCs and unveil the gene clusters responsible for bone formation. Bioinformatics tools were used to identify the biological processes, molecular functions, hallmarks and KEGG pathways of adipose and bone marrow MSC secretome proteins. We found a substantial overlap in the functional annotations and protein compositions of both adipose and bone marrow MSC secretome indicating that MSC source may be noninfluencial with regards to tissue regeneration. Additionally, a novel network pharmacology-based analysis of the secreted proteins revealed that the commonly secreted proteins within a single source interact with multiple drugable targets of bone diseases and regulate various KEGG pathway. This study unravels the secretome profile of human adult adipose and bone marrow MSCs based on the current literature and provides valuable insights into the therapeutic use of the MSC secretome for cell-free therapies.

Ajuga taiwanensis Extract Promotes Wound-healing via Activation of PDGFR/MAPK Pathway

Chronic and prolonged wounds are a serious public problem that may severely affect the quality of life and result in psychological pressure. Fibroblasts play a crucial role in the wound process and in skin pathology. Herbal drugs have long been used for wound care worldwide. Ajuga taiwanensis (Lamiaceae) is a folk medicine for antipyretics, anti-inflammation, and reducing swelling in Taiwan. This study aimed to investigate the effect of A. taiwanensis in wound healing and the underlying mechanisms. Under human dermal fibroblast (HDF) wound-healing activity-guided fractionation, we found that a sub-fraction (AT-M) of A. taiwanensis extract (AT) and the major ingredients significantly promoted wound healing and decreased IL-1β and - 6 expressions on HDFs. Furthermore, the fraction of AT-M enhanced wound healing on C57BL/6 mouse skins, increased PDGFR expressions, and activated the PDGFR/MAPK pathway. Taken together, A. taiwanensis extracts promote wound healing by the PDGFR pathway and lead to enhanced cell spreading and motility, thereby having a possible beneficial effect on wound healing.

Amyloid precursor protein as a fibrosis marker in infants with biliary atresia

BACKGROUND

Biliary atresia (BA) is a rare condition of unknown origin in newborns with jaundice. In BA bile ducts are non-functional, causing neonatal cholestasis and following liver fibrosis and failure.

METHODS

This retrospective study included liver biopsies of 14 infants with BA aged [mean ± SD] 63 ± 23 days. Patients were grouped according to the clinical course (jaundice-free vs recurrent jaundice vs required liver transplantation or liver fibrosis (Ishak fibrosis score)) and followed for 1.61-5.64 years (mean 4.03). Transcriptome profiles were assessed using a panel of 768 fibrosis-specific genes, reanalyzed via qRT-PCR, and confirmed via immunostaining. Plasma from an additional 30 BA infants and 10 age-matched controls were used for amyloid precursor protein (APP) quantification by ELISA.

RESULTS

Different clinical outcome groups showed a homogeneous mRNA expression. Altered amyloid-metabolism-related gene expression was found between cases with Ishak fibrosis score greater than 4. Immunostaining confirmed a distinct presence of APP in the livers of all BA subjects. APP plasma levels were higher in BA than in age-matched controls and correlated with the histological fibrosis grade.

CONCLUSIONS

These results suggest that amyloidosis may contribute to BA and liver fibrosis, indicating that APP could serve as a potential liquid biomarker for these conditions.

IMPACT

Biliary atresia patients with higher fibrosis scores according to Ishak have higher hepatic expression of amyloid-related genes while amyloid precursor protein accumulates in the liver and increases in the circulation. After a recent study revealed beta-amyloid deposition as a mechanism potentially involved in biliary atresia, we were able to correlate amyloid-metabolism-related transcript levels as well as amyloid precursor protein tissue and plasma levels with the degree of hepatic fibrosis. These findings suggest that amyloid precursor protein is a fibrosis marker in infants with biliary atresia, reinforcing the role of amyloid metabolism in the pathogenesis of this serious disease.

Aryl Hydrocarbon Receptor Activation in Pulmonary Alveolar Epithelial Cells Limits Inflammation and Preserves Lung Epithelial Cell Integrity

The aryl hydrocarbon receptor (AHR) is a receptor/transcription factor widely expressed in the lung. The physiological roles of AHR expressed in the alveolar epithelium remain unclear. In this study, we tested the hypothesis that alveolar epithelial AHR activity plays an important role in modulating inflammatory responses and maintaining alveolar integrity during lung injury and repair. AHR is expressed in alveolar epithelial cells (AECs) and is active. AHR activation with the endogenous AHR ligand, FICZ (5,11-dihydroindolo[3,2-b] carbazole-6-carboxaldehyde), significantly suppressed inflammatory cytokine expression in response to inflammatory stimuli in primary murine AECs and in the MLE-15 epithelial cell line. In an LPS model of acute lung injury in mice, coadministration of FICZ with LPS suppressed protein leak, reduced neutrophil accumulation in BAL fluid, and suppressed inflammatory cytokine expression in lung tissue and BAL fluid. Relevant to healing following inflammatory injury, AHR activation suppressed TGF-β-induced expression of genes associated with epithelial-mesenchymal transition. Knockdown of AHR in primary AECs with shRNA or in CRISPR-Cas-9-induced MLE-15 cells resulted in upregulation of α-smooth muscle actin (αSma), Col1a1, and Fn1 and reduced expression of epithelial genes Col4a1 and Sdc1. MLE-15 clones lacking AHR demonstrated accelerated wound closure in a scratch model. AHR activation with FICZ enhanced barrier function (transepithelial electrical resistance) in primary murine AECs and limited decline of transepithelial electrical resistance following inflammatory injury. AHR activation in AECs preserves alveolar integrity by modulating inflammatory cytokine expression while enhancing barrier function and limiting stress-induced expression of mesenchymal genes.

Epithelial-mesenchymal transition in tissue repair and degeneration

Epithelial-mesenchymal transitions (EMTs) are the epitome of cell plasticity in embryonic development and cancer; during EMT, epithelial cells undergo dramatic phenotypic changes and become able to migrate to form different tissues or give rise to metastases, respectively. The importance of EMTs in other contexts, such as tissue repair and fibrosis in the adult, has become increasingly recognized and studied. In this Review, we discuss the function of EMT in the adult after tissue damage and compare features of embryonic and adult EMT. Whereas sustained EMT leads to adult tissue degeneration, fibrosis and organ failure, its transient activation, which confers phenotypic and functional plasticity on somatic cells, promotes tissue repair after damage. Understanding the mechanisms and temporal regulation of different EMTs provides insight into how some tissues heal and has the potential to open new therapeutic avenues to promote repair or regeneration of tissue damage that is currently irreversible. We also discuss therapeutic strategies that modulate EMT that hold clinical promise in ameliorating fibrosis, and how precise EMT activation could be harnessed to enhance tissue repair.

Lack of basic rationale in epithelial-mesenchymal transition and its related concepts

Epithelial-mesenchymal transition (EMT) is defined as a cellular process during which epithelial cells acquire mesenchymal phenotypes and behavior following the downregulation of epithelial features. EMT and its reversed process, the mesenchymal-epithelial transition (MET), and the special form of EMT, the endothelial-mesenchymal transition (EndMT), have been considered as mainstream concepts and general rules driving developmental and pathological processes, particularly cancer. However, discrepancies and disputes over EMT and EMT research have also grown over time. EMT is defined as transition between two cellular states, but it is unanimously agreed by EMT researchers that (1) neither the epithelial and mesenchymal states nor their regulatory networks have been clearly defined, (2) no EMT markers or factors can represent universally epithelial and mesenchymal states, and thus (3) EMT cannot be assessed on the basis of one or a few EMT markers. In contrast to definition and proposed roles of EMT, loss of epithelial feature does not cause mesenchymal phenotype, and EMT does not contribute to embryonic mesenchyme and neural crest formation, the key developmental events from which the EMT concept was derived. EMT and MET, represented by change in cell shapes or adhesiveness, or symbolized by EMT factors, are biased interpretation of the overall change in cellular property and regulatory networks during development and cancer progression. Moreover, EMT and MET are consequences rather than driving factors of developmental and pathological processes. The true meaning of EMT in some developmental and pathological processes, such as fibrosis, needs re-evaluation. EMT is believed to endow malignant features, such as migration, stemness, etc., to cancer cells. However, the core property of cancer (tumorigenic) cells is neural stemness, and the core EMT factors are components of the regulatory networks of neural stemness. Thus, EMT in cancer progression is misattribution of the roles of neural stemness to the unknown mesenchymal state. Similarly, neural crest EMT is misattribution of intrinsic property of neural crest cells to the unknown mesenchymal state. Lack of basic rationale in EMT and related concepts urges re-evaluation of their significance as general rules for understanding developmental and pathological processes, and re-evaluation of their significance in scientific research.

IL-1β-activated PI3K/AKT and MEK/ERK pathways coordinately promote induction of partial epithelial-mesenchymal transition

Epithelial-mesenchymal transition (EMT) is a cellular process in embryonic development, wound healing, organ fibrosis, and cancer metastasis. Previously, we and others have reported that proinflammatory cytokine interleukin-1β (IL-1β) induces EMT. However, the exact mechanisms, especially the signal transduction pathways, underlying IL-1β-mediated EMT are not yet completely understood. Here, we found that IL-1β stimulation leads to the partial EMT-like phenotype in human lung epithelial A549 cells, including the gain of mesenchymal marker (vimentin) and high migratory potential, without the complete loss of epithelial marker (E-cadherin). IL-1β-mediated partial EMT induction was repressed by PI3K inhibitor LY294002, indicating that the PI3K/AKT pathway plays a significant role in the induction. In addition, ERK1/2 inhibitor FR180204 markedly inhibited the IL-1β-mediated partial EMT induction, demonstrating that the MEK/ERK pathway was also involved in the induction. Furthermore, we found that the activation of the PI3K/AKT and MEK/ERK pathways occurred downstream of the epidermal growth factor receptor (EGFR) pathway and the IL-1 receptor (IL-1R) pathway, respectively. Our findings suggest that the PI3K/AKT and MEK/ERK pathways coordinately promote the IL-1β-mediated partial EMT induction. The inhibition of not one but both pathways is expected yield clinical benefits by preventing partial EMT-related disorders such as organ fibrosis and cancer metastasis.

P2 X 7 receptor is a critical regulator of extracellular ATP-induced profibrotic genes expression in rat kidney: implication of transforming growth factor-β/Smad signaling pathway

This study was designed to investigate the potential of extracellular adenosine 5'-triphosphate (ATP) via the P2 X 7 receptor to activate the renal fibrotic processes in rats. The present study demonstrates that administration of ATP rapidly activated transforming growth factor-β (TGF-β) to induce phosphorylation of Smad-2/3. Renal connective tissue growth factor (CTGF) and tissue inhibitor of metalloproteinase-1 (TIMP-1) mRNA and protein expressions were also increased following ATP administration. A decrease in TGF-β amount in serum as well as renal Smad-2/3 phosphorylation was noticed in animals pre-treated with the specific antagonist of P2 X 7 receptor, A 438,079. In addition, a significant reduction in mRNA and protein expression of CTGF and TIMP-1were also observed in the kidneys of those animals. Collectively, the current findings demonstrate that ATP has the ability to augment TGF-β-mediated Smad-2/3 phosphorylation and enhance the expression of the pro-fibrotic genes, CTGF and TIMP-1, an effect that is largely mediated via P2 X 7 receptor.

Enhydrin suppresses the malignant phenotype of GBM via Jun/Smad7/TGF-β1 signaling pathway

GBM is the most threatening form of brain tumor. The advancement of GBM is propelled by the growth, infiltration, and movement of cancer cells. Understanding the underlying mechanisms and identifying new therapeutic agents are crucial for effective GBM treatment. Our research focused on examining the withhold influence of Enhydrin on the destructive activity of GBM cells, both in laboratory settings and within living organisms. By employing network pharmacology and bioinformatics analysis, we have determined that Jun serves as the gene of interest, and EMT as the critical signaling pathway. Mechanistically, Enhydrin inhibits the activity of the target gene Jun to increase the expression of Smad7, which is infinitively regulated by the transcription factor Jun, and as the inhibitory transcription factor, Smad7 can down-regulate TGF-β1 and the subsequent Smad2/3 signaling pathway. Consequently, this whole process greatly hinders the EMT mechanism of GBM, leading to the notable decline in cell proliferation, invasion, and migration. In summary, our research shows that Enhydrin hinders EMT by focusing on the Jun/Smad7/TGF-β1 signaling pathway, presenting a promising target for treating GBM. Moreover, Enhydrin demonstrates encouraging prospects as a new medication for GBM treatment.

Design and evaluation of a bilayered dermal/hypodermal 3D model using a biomimetic hydrogel formulation

Due to the limitations of the current skin wound treatments, it is highly valuable to have a wound healing formulation that mimics the extracellular matrix (ECM) and mechanical properties of natural skin tissue. Here, a novel biomimetic hydrogel formulation has been developed based on a mixture of Agarose-Collagen Type I (AC) combined with skin ECM-related components: Dermatan sulfate (DS), Hyaluronic acid (HA), and Elastin (EL) for its application in skin tissue engineering (TE). Different formulations were designed by combining AC hydrogels with DS, HA, and EL. Cell viability, hemocompatibility, physicochemical, mechanical, and wound healing properties were investigated. Finally, a bilayered hydrogel loaded with fibroblasts and mesenchymal stromal cells was developed using the Ag-Col I-DS-HA-EL (ACDHE) formulation. The ACDHE hydrogel displayed the best in vitro results and acceptable physicochemical properties. Also, it behaved mechanically close to human native skin and exhibited good cytocompatibility. Environmental scanning electron microscopy (ESEM) analysis revealed a porous microstructure that allows the maintenance of cell growth and ECM-like structure production. These findings demonstrate the potential of the ACDHE hydrogel formulation for applications such as an injectable hydrogel or a bioink to create cell-laden structures for skin TE.

Interleukin-11 Is Involved in Hyperoxia-induced Bronchopulmonary Dysplasia in Newborn Mice by Mediating Epithelium-Fibroblast Cross-talk

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a chronic lung disorder predominantly affecting preterm infants. Oxygen therapy, a common treatment for BPD, often leads to hyperoxia-induced pulmonary damage, particularly targeting alveolar epithelial cells (AECs). Crucially, disrupted lung epithelium-fibroblast interactions significantly contribute to BPD's pathogenesis. Previous studies on interleukin-11 (IL-11) in lung diseases have yielded conflicting results. Recent research, however, highlights IL-11 as a key regulator of fibrosis, stromal inflammation, and epithelial dysfunction. Despite this, the specific role of IL-11 in BPD remains underexplored. Our transcriptome analysis of normal and hyperoxia-exposed murine lung tissues revealed an increased expression of IL-11 RNA. This study aimed to investigate IL-11's role in modulating the disrupted interactions between AECs and fibroblasts in BPD.

METHODS

BPD was modeled in vivo by exposing C57BL/6J neonatal mice to hyperoxia. Histopathological changes in lung tissue were evaluated with hematoxylin-eosin staining, while lung fibrosis was assessed using Masson staining and immunohistochemistry (IHC). To investigate IL-11's role in pulmonary injury contributing to BPD, IL-11 levels were reduced through intraperitoneal administration of IL-11RαFc in hyperoxia-exposed mice. Additionally, MLE-12 cells subjected to 95% oxygen were collected and co-cultured with mouse pulmonary fibroblasts (MPFs) to measure α-SMA and Collagen I expression levels. IL-11 levels in the supernatants were quantified using an enzyme-linked immunosorbent assay (ELISA).

RESULTS

Both IHC and Masson staining revealed that inhibiting IL-11 expression alleviated pulmonary fibrosis in neonatal mice induced by hyperoxia, along with reducing the expression of fibrosis markers α-SMA and collagen I in lung tissue. In vitro analysis showed a significant increase in IL-11 levels in the supernatant of MLE-12 cells treated with hyperoxia. Silencing IL-11 expression in MLE-12 cells reduced α-SMA and collagen I concentrations in MPFs co-cultured with the supernatant of hyperoxia-treated MLE-12 cells. Additionally, ERK inhibitors decreased α-SMA and collagen I levels in MPFs co-cultured with the supernatant of hyperoxia-treated MLE-12 cells. Clinical studies found increased IL-11 levels in tracheal aspirates (TA) of infants with BPD.

CONCLUSION

This research reveals that hyperoxia induces IL-11 secretion in lung epithelium. Additionally, IL-11 derived from lung epithelium emerged as a crucial mediator in myofibroblast differentiation via the ERK signaling pathway, highlighting its potential therapeutic value in BPD treatment.

Epicardial EMT and cardiac repair: an update

Epicardial epithelial-to-mesenchymal transition (EMT) plays a pivotal role in both heart development and injury response and involves dynamic cellular changes that are essential for cardiogenesis and myocardial repair. Specifically, epicardial EMT is a crucial process in which epicardial cells lose polarity, migrate into the myocardium, and differentiate into various cardiac cell types during development and repair. Importantly, following EMT, the epicardium becomes a source of paracrine factors that support cardiac growth at the last stages of cardiogenesis and contribute to cardiac remodeling after injury. As such, EMT seems to represent a fundamental step in cardiac repair. Nevertheless, endogenous EMT alone is insufficient to stimulate adequate repair. Redirecting and amplifying epicardial EMT pathways offers promising avenues for the development of innovative therapeutic strategies and treatment approaches for heart disease. In this review, we present a synthesis of recent literature highlighting the significance of epicardial EMT reactivation in adult heart disease patients.

The receptor protein tyrosine phosphatase PTPRK promotes intestinal repair and catalysis-independent tumour suppression

PTPRK is a receptor tyrosine phosphatase that is linked to the regulation of growth factor signalling and tumour suppression. It is stabilized at the plasma membrane by trans homophilic interactions upon cell-cell contact. PTPRK regulates cell-cell adhesion but is also reported to regulate numerous cancer-associated signalling pathways. However, the signalling mechanism of PTPRK remains to be determined. Here, we find that PTPRK regulates cell adhesion signalling, suppresses invasion and promotes collective, directed migration in colorectal cancer cells. In vivo, PTPRK supports recovery from inflammation-induced colitis. In addition, we confirm that PTPRK functions as a tumour suppressor in the mouse colon and in colorectal cancer xenografts. PTPRK regulates growth factor and adhesion signalling, and suppresses epithelial to mesenchymal transition (EMT). Contrary to the prevailing notion that PTPRK directly dephosphorylates EGFR, we find that PTPRK regulation of both EGFR and EMT is independent of its catalytic function. This suggests that additional adaptor and scaffold functions are important features of PTPRK signalling.

T-plastin contributes to epithelial-mesenchymal transition in human lung cancer cells through FAK/AKT/Slug axis signaling pathway

T-plastin (PLST), a member of the actin-bundling protein family, plays crucial roles in cytoskeletal structure, regulation, and motility. Studies have shown that the plastin family is associated with the malignant characteristics of cancer, such as circulating tumor cells and metastasis, by inducing epithelialmesenchymal transition (EMT) in various cancer cells. However, the role of PLST in the EMT of human lung cancer cells remains unclear. In this study, we observed that PLST overexpression enhanced cell migratory and invasive abilities, whereas its downregulation resulted in their suppression. Moreover, PLST expression levels were associated with the expression patterns of EMT markers, including E-cadherin, vimentin, and Slug. Furthermore, the phosphorylation levels of focal adhesion kinase (FAK) and AKT serine/threonine kinase (AKT) were dependent on PLST expression levels. These findings indicate that PLST induces the migration and invasion of human lung cancer cells by promoting Slug-mediated EMT via the FAK/AKT signaling pathway. [BMB Reports 2024; 57(6): 305-310].

The implication of ciliary signaling pathways for epithelial-mesenchymal transition

Epithelial-to-mesenchymal transition (EMT), which plays an essential role in development, tissue repair and fibrosis, and cancer progression, is a reversible cellular program that converts epithelial cells to mesenchymal cell states characterized by motility-invasive properties. The mostly signaling pathways that initiated and controlled the EMT program are regulated by a solitary, non-motile organelle named primary cilium. Acting as a signaling nexus, primary cilium dynamically concentrates signaling molecules to respond to extracellular cues. Recent research has provided direct evidence of connection between EMT and primary ciliogenesis in multiple contexts, but the mechanistic understanding of this relationship is complicated and still undergoing. In this review, we describe the current knowledge about the ciliary signaling pathways involved in EMT and list the direct evidence that shows the link between them, trying to figure out the intricate relationship between EMT and primary ciliogenesis, which may aid the future development of primary cilium as a novel therapeutic approach targeted to EMT.

Scutellarin Alleviates Ovalbumin-Induced Airway Remodeling in Mice and TGF-β-Induced Pro-fibrotic Phenotype in Human Bronchial Epithelial Cells via MAPK and Smad2/3 Signaling Pathways

Asthma is a chronic inflammatory disease characterized by airway hyperresponsiveness (AHR), inflammation, and remodeling. Epithelial-mesenchymal transition (EMT) is an essential player in these alterations. Scutellarin is isolated from Erigeron breviscapus. Its vascular relaxative, myocardial protective, and anti-inflammatory effects have been well established. This study was designed to detect the biological roles of scutellarin in asthma and its related mechanisms. The asthma-like conditions were induced by ovalbumin challenges. The airway resistance and dynamic compliance were recorded as the results of AHR. Bronchoalveolar lavage fluid (BALF) was collected and processed for differential cell counting. Hematoxylin and eosin staining, periodic acid-Schiff staining, and Masson staining were conducted to examine histopathological changes. The levels of asthma-related cytokines were measured by enzyme-linked immunosorbent assay. For in vitro analysis, the 16HBE cells were stimulated with 10 ng/mL transforming growth beta-1 (TGF-β1). Cell migration was estimated by Transwell assays and wound healing assays. E-cadherin, N-cadherin, and α-smooth muscle actin (α-SMA) were analyzed by western blotting, real-time quantitative polymerase chain reaction, immunofluorescence staining, and immunohistochemistry staining. The underlying mechanisms of the mitogen-activated protein kinase (MAPK) and Smad pathways were investigated by western blotting. In an ovalbumin-induced asthmatic mouse model, scutellarin suppressed inflammation and inflammatory cell infiltration into the lungs and attenuated AHR and airway remodeling. Additionally, scutellarin inhibited airway EMT (upregulated E-cadherin level and downregulated N-cadherin and α-SMA) in ovalbumin-challenged asthmatic mice. For in vitro analysis, scutellarin prevented the TGF-β1-induced migration and EMT in 16HBE cells. Mechanistically, scutellarin inhibits the phosphorylation of Smad2, Smad3, ERK, JNK, and p38 in vitro and in vivo. In conclusion, scutellarin can inactivate the Smad/MAPK pathways to suppress the TGF-β1-stimulated epithelial fibrosis and EMT and relieve airway inflammation and remodeling in asthma. This study provides a potential therapeutic strategy for asthma.

Single-cell landscape reveals the epithelial cell-centric pro-inflammatory immune microenvironment in dry eye development

Dry eye disease (DED) is a prevalent chronic eye disease characterized by an aberrant inflammatory response in ocular surface mucosa. The immunological alterations underlying DED remain largely unknown. In this study, we employed single-cell transcriptome sequencing of conjunctival tissue from environment-induced DED mice to investigate multicellular ecosystem and functional changes at different DED stages. Our results revealed an epithelial subtype with fibroblastic characteristics and pro-inflammatory effects emerging in the acute phase of DED. We also found that T helper (Th)1, Th17, and regulatory T cells (Treg) were the dominant clusters of differentiation (CD)4+ T-cell types involved in regulating immune responses and identified three distinct macrophage subtypes, with the CD72+CD11c+ subtype enhancing chronic inflammation. Furthermore, bulk transcriptome analysis of video display terminal-induced DED consistently suggested the presence of the pro-inflammatory epithelial subtype in human conjunctiva. Our findings have uncovered a DED-associated pro-inflammatory microenvironment in the conjunctiva, centered around epithelial cells, involving interactions with macrophages and CD4+ T cells, which deepens our understanding of ocular surface mucosal immune responses during DED progression.

Recent advances in molecular mechanisms of skin wound healing and its treatments

The skin, being a multifaceted organ, performs a pivotal function in the complicated wound-healing procedure, which encompasses the triggering of several cellular entities and signaling cascades. Aberrations in the typical healing process of wounds may result in atypical scar development and the establishment of a persistent condition, rendering patients more vulnerable to infections. Chronic burns and wounds have a detrimental effect on the overall quality of life of patients, resulting in higher levels of physical discomfort and socio-economic complexities. The occurrence and frequency of prolonged wounds are on the rise as a result of aging people, hence contributing to escalated expenditures within the healthcare system. The clinical evaluation and treatment of chronic wounds continue to pose challenges despite the advancement of different therapeutic approaches. This is mainly owing to the prolonged treatment duration and intricate processes involved in wound healing. Many conventional methods, such as the administration of growth factors, the use of wound dressings, and the application of skin grafts, are used to ease the process of wound healing across diverse wound types. Nevertheless, these therapeutic approaches may only be practical for some wounds, highlighting the need to advance alternative treatment modalities. Novel wound care technologies, such as nanotherapeutics, stem cell treatment, and 3D bioprinting, aim to improve therapeutic efficacy, prioritize skin regeneration, and minimize adverse effects. This review provides an updated overview of recent advancements in chronic wound healing and therapeutic management using innovative approaches.

Dual-color FISH analyses of xenogeneic human fibroblast sheets transplanted to repair lung pleural defects in an immunocompromised rat model

BACKGROUND

Pulmonary air leaks (PALs) due to visceral pleura injury during surgery is frequently observed after pulmonary resections and the complication is difficult to avoid in thoracic surgery. The development of postoperative PALs is the most common cause of prolonged hospitalization. Previously, we reported that PALs sealants using autologous dermal fibroblast sheets (DFSs) harvested from temperature-responsive culture dishes successfully closed intraoperative PALs during lung resection.

OBJECTIVE

In this study, we investigated the fate of human DFSs xenogenetically transplanted onto lung surfaces to seal PALs of immunocompromised rat. Dual-color FISH analyses of human fibroblast was employed to detect transplantation human cells on the lung surface.

RESULTS

One month after transplantation, FISH analyses revealed that transplanted human fibroblasts still composed a sheet-structure, and histology also showed that beneath the sheet's angiogenesis migrating into the sheets was observed from the recipient tissues. FISH analyses revealed that even at 3 months after transplantation, the transplanted human fibroblasts still remained in the sheet. Dual-color FISH analyses of the transplanted human fibroblasts were sparsely present as a result of the cells reaching the end of their lifespan, the cells producing extracellular matrix, and remained inside the cell sheet and did not invade the lungs of the host.

CONCLUSIONS

DFS-transplanted human fibroblasts showed that they are retained within cell sheets and do not invade the lungs of the host.

Epithelial-mesenchymal transition contrast in the amputated tail and limb of the northern house gecko, Hemidactylus flaviviridis

The northern house gecko Hemidactylus flaviviridis exhibits appendage-specific responses to injuries. The autotomized tail regenerates, whereas the severed limb fails to regrow. Many site-specific cellular processes influence tail regeneration. Herein, we analyzed the epithelial-mesenchymal transition contrast in the lizard's amputated appendages (tail and limb). Morphological observations in the healing frame indicated the formation of regeneration blastema in the tail and scar formation in limb. Histology of the tail showed that epithelial cells closer to mesenchyme appeared less columnar and loosely packed, with little intercellular matrix. Whereas in the limb, the columnar epithelial cells remained tightly packed. Collagen deposition was seen in the limb at the intersection of wound epithelium and mesenchyme, favoring scarring by blocking the epithelial-mesenchymal transition. Markers for epithelial-mesenchymal transition were assessed at transcript and protein levels. The regenerating tail showed upregulation of N-cadherin, vimentin, and PCNA, favoring epithelial-mesenchymal transition, cell migration, and proliferation, respectively. In contrast, the scarring limb showed persistently elevated levels of E-cadherin and EpCAM, indicating retention of epithelial characteristics. An attempt was made to screen the resident epithelial stem cell population in both appendages to check their potential role in the epithelial-mesenchymal transition (EMT), hence the differential wound healing. Upregulation in transcript and protein levels of Nanog and Sox2 was observed in the regenerating tail. Fluorescence-activated cell sorting (FACS) provided supporting evidence that the epithelial stem cell population in tail remained significantly higher than in limb. Thus, this study focuses on the mechanistic role of the epithelial-mesenchymal transition in wound healing, highlighting the molecular details of regeneration and scarring events.

DNA-PKcs/AKT1 inhibits epithelial-mesenchymal transition during radiation-induced pulmonary fibrosis by inducing ubiquitination and degradation of Twist1

INTRODUCTION

Radiation-induced pulmonary fibrosis (RIPF) is a chronic, progressive, irreversible lung interstitial disease that develops after radiotherapy. Although several previous studies have focused on the mechanism of epithelial-mesenchymal transition (EMT) in lung epithelial cells, the essential factors involved in this process remain poorly understood. The DNA-dependent protein kinase catalytic subunit (DNA-PKcs) exhibits strong repair capacity when cells undergo radiation-induced damage; whether DNA-PKcs regulates EMT during RIPF remains unclear.

OBJECTIVES

To investigate the role and molecular mechanism of DNA-PKcs in RIPF and provide an important theoretical basis for utilising DNA-PKcs-targeted drugs for preventing RIPF.

METHODS

DNA-PKcs knockout (DPK-/-) mice were generated via the Cas9/sgRNA technique and subjected to whole chest ionizing radiation (IR) at a 20 Gy dose. Before whole chest IR, the mice were intragastrically administered the DNA-PKcs-targeted drug VND3207. Lung tissues were collected at 1 and 5 months after IR.

RESULTS

The expression of DNA-PKcs is low in pulmonary fibrosis (PF) patients. DNA-PKcs deficiency significantly exacerbated RIPF by promoting EMT in lung epithelial cells. Mechanistically, DNA-PKcs deletion by shRNA or inhibitor NU7441 maintained the protein stability of Twist1. Furthermore, AKT1 mediated the interaction between DNA-PKcs and Twist1. High Twist1 expression and EMT-associated changes caused by DNA-PKcs deletion were blocked by insulin-like growth factor-1 (IGF-1), an AKT1 agonist. The radioprotective drug VND3207 prevented IR-induced EMT and alleviated RIPF in mice by stimulating the kinase activity of DNA-PKcs.

CONCLUSION

Our study clarified the critical role and mechanism of DNA-PKcs in RIPF and showed that it could be a potential target for preventing RIPF.

Incorporation of Decidual Stromal Cells Derived Exosomes in Sodium Alginate Hydrogel as an Innovative Therapeutic Strategy for Advancing Endometrial Regeneration and Reinstating Fertility

Intrauterine adhesion (IUA) stands as a prevalent medical condition characterized by endometrial fibrosis and scar tissue formation within the uterine cavity, resulting in infertility and, in severe cases, recurrent miscarriages. Cell therapy, especially with stem cells, offers an alternative to surgery, but concerns about uncontrolled differentiation and tumorigenicity limit its use. Exosomes, more stable and immunogenicity-reduced than parent cells, have emerged as a promising avenue for IUA treatment. In this study, a novel approach has been proposed wherein exosomes originating from decidual stromal cells (DSCs) are encapsulated within sodium alginate hydrogel (SAH) scaffolds to repair endometrial damage and restore fertility in a mouse IUA model. Current results demonstrate that in situ injection of DSC-derived exosomes (DSC-exos)/SAH into the uterine cavity has the capability to induce uterine angiogenesis, initiate mesenchymal-to-epithelial transformation (MET), facilitate collagen fiber remodeling and dissolution, promote endometrial regeneration, enhance endometrial receptivity, and contribute to the recovery of fertility. RNA sequencing and advanced bioinformatics analysis reveal miRNA enrichment in exosomes, potentially supporting endometrial repair. This finding elucidates how DSC-exos/SAH mechanistically fosters collagen ablation, endometrium regeneration, and fertility recovery, holding the potential to introduce a novel IUA treatment and offering invaluable insights into the realm of regenerative medicine.

Galectins in epithelial-mesenchymal transition: roles and mechanisms contributing to tissue repair, fibrosis and cancer metastasis

Galectins are soluble glycan-binding proteins that interact with a wide range of glycoproteins and glycolipids and modulate a broad spectrum of physiological and pathological processes. The expression and subcellular localization of different galectins vary among tissues and cell types and change during processes of tissue repair, fibrosis and cancer where epithelial cells loss differentiation while acquiring migratory mesenchymal phenotypes. The epithelial-mesenchymal transition (EMT) that occurs in the context of these processes can include modifications of glycosylation patterns of glycolipids and glycoproteins affecting their interactions with galectins. Moreover, overexpression of certain galectins has been involved in the development and different outcomes of EMT. This review focuses on the roles and mechanisms of Galectin-1 (Gal-1), Gal-3, Gal-4, Gal-7 and Gal-8, which have been involved in physiologic and pathogenic EMT contexts.

Lithium chloride promotes mesenchymal-epithelial transition in murine cutaneous wound healing via inhibiting CXCL9 and IGF2

Cutaneous wound healing is a challenge in plastic and reconstructive surgery. In theory, cells undergoing mesenchymal transition will achieve re-epithelialization through mesenchymal-epithelial transition at the end of wound healing. But in fact, some pathological stimuli will inhibit this biological process and result in scar formation. If mesenchymal-epithelial transition can be activated at the corresponding stage, the ideal wound healing may be accomplished. Two in vivo skin defect mouse models and dermal-derived mesenchymal cells were used to evaluate the effect of lithium chloride in wound healing. The mesenchymal-epithelial transition was detected by immunohistochemistry staining. In vivo, differentially expressed genes were analysed by transcriptome analyses and the subsequent testing was carried out. We found that lithium chloride could promote murine cutaneous wound healing and facilitate mesenchymal-epithelial transition in vivo and in vitro. In lithium chloride group, scar area was smaller and the collagen fibres are also orderly arranged. The genes related to mesenchyme were downregulated and epithelial mark genes were activated after intervention. Moreover, transcriptome analyses suggested that this effect might be related to the inhibition of CXCL9 and IGF2, subsequent assays demonstrated it. Lithium chloride can promote mesenchymal-epithelial transition via downregulating CXCL9 and IGF2 in murine cutaneous wound healing, the expression of IGF2 is regulated by β-catenin. It may be a potential promising therapeutic drug for alleviating postoperative scar and promoting re-epithelialization in future.

circPVT1 promotes silica-induced epithelial-mesenchymal transition by modulating the miR-497-5p/TCF3 axis

Epithelial-mesenchymal transition (EMT) is a vital pathological feature of silica-induced pulmonary fibrosis. However, whether circRNA is involved in the process remains unclear. The present study aimed to investigate the role of circPVT1 in the silica-induced EMT and the underlying mechanisms. We found that an elevated expression of circPVT1 promoted EMT and enhanced the migratory capacity of silica-treated epithelial cells. The isolation of cytoplasmic and nuclear separation assay showed that circPVT1 was predominantly expressed in the cytoplasm. RNA immunoprecipitation assay and RNA pull-down experiment indicated that cytoplasmic-localized circPVT1 was capable of binding to miR-497-5p. Furthermore, we found that miR-497-5p attenuated the silica-induced EMT process by targeting transcription factor 3 (TCF3), an E-cadherin transcriptional repressor, in the silica-treated epithelial cells. Collectively, these results reveal a novel role of the circPVT1/miR-497-5p/TCF3 axis in the silica-induced EMT process in lung epithelial cells. Once validated, this finding may provide a potential theoretical basis for the development of interventions and treatments for pulmonary fibrosis.

The role of inflammation in silicosis

Silicosis is a chronic illness marked by diffuse fibrosis in lung tissue resulting from continuous exposure to SiO2-rich dust in the workplace. The onset and progression of silicosis is a complicated and poorly understood pathological process involving numerous cells and molecules. However, silicosis poses a severe threat to public health in developing countries, where it is the most prevalent occupational disease. There is convincing evidence supporting that innate and adaptive immune cells, as well as their cytokines, play a significant role in the development of silicosis. In this review, we describe the roles of immune cells and cytokines in silicosis, and summarize current knowledge on several important inflammatory signaling pathways associated with the disease, aiming to provide novel targets and strategies for the treatment of silicosis-related inflammation.

Osteopontin-driven partial epithelial-mesenchymal transition governs the development of middle ear cholesteatoma

Cholesteatoma is a common disease of the middle ear. Currently, surgical removal is the only treatment option and patients face a high risk of relapse. The molecular basis of cholesteatoma remains largely unknown. Here, we show that Osteopontin (OPN), a predominantly secreted protein, plays a crucial role in the development of middle ear cholesteatoma. Global transcriptome analysis revealed the loss of epithelial features and an enhanced immune response in human cholesteatoma tissues. Quantitative RT-PCR and immunohistochemical staining of middle ear cholesteatoma validated the reduced expression of epithelial markers, as well as the elevated expression of mesenchymal markers including Vimentin and Fibronectin, but not N-Cadherin, α-smooth muscle actin (α-SMA) or ferroptosis suppressor protein 1 (FSP1), indicating a partial epithelial-mesenchymal transition (EMT) state. Besides, the expression of OPN was significantly elevated in human cholesteatoma tissues. Treatment with OPN promoted cell proliferation, survival and migration and led to a partial EMT in immortalized human keratinocyte cells. Importantly, blockade of OPN signaling could remarkably improve the cholesteatoma-like symptoms in SD rats. Our mechanistic study demonstrated that the AKT-zinc finger E-box binding homeobox 2 (ZEB2) axis mediated the effects of OPN. Overall, these findings suggest that targeting the OPN signaling represents a promising strategy for the treatment of middle ear cholesteatoma.