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Progress in Retinal and Eye Research Sep 2023The limbus is a transition from the cornea to conjunctiva and sclera. In human eyes, this thin strip has a rich variation of tissue structures and composition, typifying... (Review)
Review
The limbus is a transition from the cornea to conjunctiva and sclera. In human eyes, this thin strip has a rich variation of tissue structures and composition, typifying a change from scleral irregularity and opacity to corneal regularity and transparency; a variation from richly vascularized conjunctiva and sclera to avascular cornea; the neural passage and drainage of aqueous humor. The limbal stroma is enriched with circular fibres running parallel to the corneal circumference, giving its unique role in absorbing small pressure changes to maintain corneal curvature and refractivity. It contains specific niches housing different types of stem cells for the corneal epithelium, stromal keratocytes, corneal endothelium, and trabecular meshwork. This truly reflects the important roles of the limbus in ocular physiology, and the limbal functionality is crucial for corneal health and the entire visual system. Since the anterior limbus containing epithelial structures and limbal epithelial stem cells has been extensively reviewed, this article is focused on the posterior limbus. We have discussed the structural organization and cellular components of the region beneath the limbal epithelium, the characteristics of stem cell types: namely corneal stromal stem cells, endothelial progenitors and trabecular meshwork stem cells, and recent advances leading to the emergence of potential cell therapy options to replenish their respective mature cell types and to correct defects causing corneal abnormalities. We have reviewed different clinical disorders associated with defects of the posterior limbus and summarized the available preclinical and clinical evidence about the developing topic of cell-based therapy for corneal disorders.
Topics: Humans; Limbus Corneae; Cornea; Epithelium, Corneal; Corneal Diseases; Stem Cells
PubMed: 37392960
DOI: 10.1016/j.preteyeres.2023.101192 -
Expert Review of Clinical Immunology 2023Epithelial-mesenchymal transition (EMT) is a type of epithelial cell dysfunction, which is widely present in the nasal mucosa of patients with chronic rhinosinusitis... (Review)
Review
INTRODUCTION
Epithelial-mesenchymal transition (EMT) is a type of epithelial cell dysfunction, which is widely present in the nasal mucosa of patients with chronic rhinosinusitis (CRS), especially CRS with nasal polyps, and contributes to pathogenesis of the disease. EMT is mediated via complex mechanisms associated with multiple signaling pathways.
AREAS COVERED
We have summarized the underlying mechanisms and signaling pathways promoting EMT in CRS. Strategies or drugs/agents targeting the genes and pathways related to the regulation of EMT are also discussed for their potential use in the treatment of CRS and asthma. A literature search of studies published in English from 2000 to 2023 was conducted using the PubMed database, employing CRS, EMT, signaling, mechanisms, targeting agents/drugs, as individual or combinations of search terms.
EXPERT OPINION
EMT in nasal epithelium not only leads to epithelial cell dysfunction but also plays an important role in nasal tissue remodeling in CRS. A comprehensive understanding of the mechanisms underlying EMT and the development of drugs/agents targeting these mechanisms may provide new treatment strategies for CRS.
Topics: Humans; Epithelial-Mesenchymal Transition; Sinusitis; Nasal Mucosa; Signal Transduction; Nasal Polyps; Epithelial Cells; Chronic Disease; Rhinitis
PubMed: 37386882
DOI: 10.1080/1744666X.2023.2232113 -
Cell Reports Sep 2023Sebaceous glands (SGs) release oils that protect our skin, but how these glands respond to injury has not been previously examined. Here, we report that SGs are largely...
Sebaceous glands (SGs) release oils that protect our skin, but how these glands respond to injury has not been previously examined. Here, we report that SGs are largely self-renewed by dedicated stem cell pools during homeostasis. Using targeted single-cell RNA sequencing, we uncovered both direct and indirect paths by which resident SG progenitors ordinarily differentiate into sebocytes, including transit through a Krt5+PPARγ+ transitional basal cell state. Upon skin injury, however, SG progenitors depart their niche, reepithelialize the wound, and are replaced by hair-follicle-derived stem cells. Furthermore, following targeted genetic ablation of >99% of SGs from dorsal skin, these glands unexpectedly regenerate within weeks. This regenerative process is mediated by alternative stem cells originating from the hair follicle bulge, is dependent upon FGFR2 signaling, and can be accelerated by inducing hair growth. Altogether, our studies demonstrate that stem cell plasticity promotes SG durability following injury.
Topics: Sebaceous Glands; Cell Differentiation; Skin; Hair Follicle; Epithelial Cells
PubMed: 37715952
DOI: 10.1016/j.celrep.2023.113121 -
Blood Advances Nov 2023Hemogenic endothelial cells (HECs) are specialized cells that undergo endothelial-to-hematopoietic transition (EHT) to give rise to the earliest precursors of...
Hemogenic endothelial cells (HECs) are specialized cells that undergo endothelial-to-hematopoietic transition (EHT) to give rise to the earliest precursors of hematopoietic progenitors that will eventually sustain hematopoiesis throughout the lifetime of an organism. Although HECs are thought to be primarily limited to the aorta-gonad-mesonephros (AGM) during early development, EHT has been described in various other hematopoietic organs and embryonic vessels. Though not defined as a hematopoietic organ, the lung houses many resident hematopoietic cells, aids in platelet biogenesis, and is a reservoir for hematopoietic stem and progenitor cells (HSPCs). However, lung HECs have never been described. Here, we demonstrate that the fetal lung is a potential source of HECs that have the functional capacity to undergo EHT to produce de novo HSPCs and their resultant progeny. Explant cultures of murine and human fetal lungs display adherent endothelial cells transitioning into floating hematopoietic cells, accompanied by the gradual loss of an endothelial signature. Flow cytometric and functional assessment of fetal-lung explants showed the production of multipotent HSPCs that expressed the EHT and pre-HSPC markers EPCR, CD41, CD43, and CD44. scRNA-seq and small molecule modulation demonstrated that fetal lung HECs rely on canonical signaling pathways to undergo EHT, including TGFβ/BMP, Notch, and YAP. Collectively, these data support the possibility that post-AGM development, functional HECs are present in the fetal lung, establishing this location as a potential extramedullary site of de novo hematopoiesis.
Topics: Animals; Mice; Humans; Hematopoiesis; Hematopoietic Stem Cells; Cell Differentiation; Endothelium; Hemangioblasts
PubMed: 37729429
DOI: 10.1182/bloodadvances.2022008347 -
International Journal of Molecular... May 2024Sjögren's Disease (SjD) is an autoimmune disease of the exocrine tissues. Etiological events result in the loss of epithelial homeostasis alongside extracellular matrix... (Review)
Review
Sjögren's Disease (SjD) is an autoimmune disease of the exocrine tissues. Etiological events result in the loss of epithelial homeostasis alongside extracellular matrix (ECM) destruction within the salivary and lacrimal glands, followed by immune cell infiltration. In this review, we have assessed the current understanding of epithelial-mesenchymal transition (EMT)-associated changes within the salivary epithelium potentially involved in salivary dysfunction and SjD pathogenesis. We performed a PubMed literature review pertaining to the determination of pathogenic events that lead to EMT-related epithelial dysfunction and signaling in SjD. Molecular patterns of epithelial dysfunction in SjD salivary glands share commonalities with EMT mediating wound healing. Pathological changes altering salivary gland integrity and function may precede direct immune involvement while perpetuating MMP9-mediated ECM destruction, inflammatory mediator expression, and eventual immune cell infiltration. Dysregulation of EMT-associated factors is present in the salivary epithelium of SjD and may be significant in initiating and perpetuating the disease. In this review, we further highlight the gap regarding mechanisms that drive epithelial dysfunction in salivary glands in the early or subclinical pre-lymphocytic infiltration stages of SjD.
Topics: Humans; Sjogren's Syndrome; Epithelial-Mesenchymal Transition; Salivary Glands; Animals; Epithelium; Epithelial Cells; Signal Transduction; Extracellular Matrix
PubMed: 38732189
DOI: 10.3390/ijms25094973 -
Cardiovascular Diabetology Nov 2023Endothelial-mesenchymal transition (EndMT) plays a crucial role in promoting myocardial fibrosis and exacerbating cardiac dysfunction. Dapagliflozin (DAPA) is a...
BACKGROUND
Endothelial-mesenchymal transition (EndMT) plays a crucial role in promoting myocardial fibrosis and exacerbating cardiac dysfunction. Dapagliflozin (DAPA) is a sodium-glucose-linked transporter 2 (SGLT-2) inhibitor that has been shown to improve cardiac function in non-diabetic patients with heart failure (HF). However, the precise mechanisms by which DAPA exerts its beneficial effects are yet to be fully elucidated.
METHODS
Isoproterenol (ISO) was used to generate a HF model in mice. For in vitro experiments, we used TGF-β1-stimulated human umbilical vein endothelial cells (HUVECs) and mouse aortic endothelial cells (MAECs).
RESULTS
Both our in vivo and in vitro results showed that EndMT occurred with decreased SIRT1 (NAD-dependent deacetylase) protein expression, which could be reversed by DAPA therapy. We found that the protective effect of DAPA was significantly impaired upon SIRT1 inhibition. Mechanistically, we observed that SIRT1 phosphorylation, a required modification for its ubiquitination and degradation, was reduced by DAPA treatment, which induces the nucleus translocation of SIRT1 and promotes its binding to the active intracellular domain of Notch1 (NICD). This interaction led to the deacetylation and degradation of NICD, and the subsequent inactivation of the Notch1 signaling pathway which contributes to ameliorating EndMT.
CONCLUSIONS
Our study revealed that DAPA can attenuate EndMT induced by ISO in non-diabetic HF mice. This beneficial effect is achieved through SIRT1-mediated deacetylation and degradation of NICD. Our findings provide greater insight into the underlying mechanisms of the therapeutic effects of DAPA in non-diabetic HF.
Topics: Humans; Animals; Mice; Sirtuin 1; Acetylation; Endothelium; Human Umbilical Vein Endothelial Cells; Epithelial-Mesenchymal Transition
PubMed: 38017499
DOI: 10.1186/s12933-023-02040-x -
Canadian Respiratory Journal 2023. Dysregulation of epithelial-mesenchymal transition (EMT) in the airway epithelium is associated with airway remodeling and the progression of pulmonary fibrosis. Many... (Review)
Review
. Dysregulation of epithelial-mesenchymal transition (EMT) in the airway epithelium is associated with airway remodeling and the progression of pulmonary fibrosis. Many treatments have been shown to inhibit airway remodeling and pulmonary fibrosis progression in asthma and chronic obstructive pulmonary disease (COPD) by regulating EMT and have few side effects. This review aimed to describe the development of airway remodeling through the EMT pathway, as well as the potential therapeutic targets in these pathways. Furthermore, this study aimed to review the current research on drugs to treat airway remodeling and their effects on the EMT pathway. . The dysregulation of EMT was associated with airway remodeling in various respiratory diseases. The cytokines released during inflammation may induce EMT and subsequent airway remodeling. Various drugs, including herbal formulations, specific herbal compounds, cytokines, amino acid or protein inhibitors, microRNAs, and vitamins, may suppress airway remodeling by inhibiting EMT-related pathways.
Topics: Humans; Pulmonary Fibrosis; Airway Remodeling; Asthma; Epithelial-Mesenchymal Transition; Cytokines
PubMed: 38074219
DOI: 10.1155/2023/3291957 -
Journal of Virology Jul 2023Respiratory syncytial virus (RSV) infection does not cause severe disease in most of us despite suffering from multiple RSV infections during our lives. However,...
Respiratory syncytial virus (RSV) infection does not cause severe disease in most of us despite suffering from multiple RSV infections during our lives. However, infants, young children, older adults, and immunocompromised patients are unfortunately vulnerable to RSV-associated severe diseases. A recent study suggested that RSV infection causes cell expansion, resulting in bronchial wall thickening . Whether the virus-induced changes in the lung airway resemble epithelial-mesenchymal transition (EMT) is still unknown. Here, we report that RSV does not induce EMT in three different lung models: the epithelial A549 cell line, primary normal human bronchial epithelial cells, and pseudostratified airway epithelium. We found that RSV increases the cell surface area and perimeter in the infected airway epithelium, which is distinct from the effects of a potent EMT inducer, transforming growth factor β1 (TGF-β1), driving cell elongation-indicative of cell motility. A genome-wide transcriptome analysis revealed that both RSV and TGF-β1 have distinct modulation patterns of the transcriptome, which suggests that RSV-induced changes are distinct from EMT. We have previously shown that RSV infects ciliated cells on the apical side of the lung airway. RSV-induced cytoskeletal inflammation contributes to an uneven increase in the height of the airway epithelium, resembling noncanonical bronchial wall thickening. RSV infection changes epithelial cell morphology by modulating actin-protein 2/3 complex-driven actin polymerization. Therefore, it is prudent to investigate whether RSV-induced cell morphological changes contribute to EMT. Our data indicate that RSV does not induce EMT in at least three different epithelial models: an epithelial cell line, primary epithelial cells, and pseudostratified bronchial airway epithelium.
Topics: Aged; Child; Child, Preschool; Humans; Infant; Actins; Cell Line; Epithelial Cells; Epithelial-Mesenchymal Transition; Respiratory Syncytial Virus Infections; Respiratory Syncytial Viruses; Transforming Growth Factor beta1
PubMed: 37338373
DOI: 10.1128/jvi.00394-23