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1.
The Role of Autophagy in Liver Epithelial Cells and Its Impact on Systemic Homeostasis.
Tomaipitinca, L, Mandatori, S, Mancinelli, R, Giulitti, F, Petrungaro, S, Moresi, V, Facchiano, A, Ziparo, E, Gaudio, E, Giampietri, C
Nutrients. 2019;(4)
Abstract
: Autophagy plays a role in several physiological and pathological processes as it controls the turnover rate of cellular components and influences cellular homeostasis. The liver plays a central role in controlling organisms' metabolism, regulating glucose storage, plasma proteins and bile synthesis and the removal of toxic substances. Liver functions are particularly sensitive to autophagy modulation. In this review we summarize studies investigating how autophagy influences the hepatic metabolism, focusing on fat accumulation and lipids turnover. We also describe how autophagy affects bile production and the scavenger function within the complex homeostasis of the liver. We underline the role of hepatic autophagy in counteracting the metabolic syndrome and the associated cardiovascular risk. Finally, we highlight recent reports demonstrating how the autophagy occurring within the liver may affect skeletal muscle homeostasis as well as different extrahepatic solid tumors, such as melanoma.
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2.
New Insights in the Pathogenesis of HPV Infection and the Associated Carcinogenic Processes: The Role of Chronic Inflammation and Oxidative Stress.
Georgescu, SR, Mitran, CI, Mitran, MI, Caruntu, C, Sarbu, MI, Matei, C, Nicolae, I, Tocut, SM, Popa, MI, Tampa, M
Journal of immunology research. 2018;:5315816
Abstract
Human papillomavirus (HPV) is a small double-stranded DNA virus with tropism for epithelial cells. To this date, over 150 genotypes are known and are classified into two major groups, low-risk and high-risk strains, depending on the ability of the virus to induce malignant transformation. The host's immunity plays a central role in the course of the infection; therefore, it may not be clinically manifest or may produce various benign or malignant lesions. The pathogenic mechanisms are complex and incompletely elucidated. Recent research suggests the role of chronic inflammation and oxidative stress (OS) in the pathogenesis of HPV infection and the associated carcinogenic processes. Chronic inflammation induces OS, which in turn promotes the perpetuation of the inflammatory process resulting in the release of numerous molecules which cause cell damage. Reactive oxygen species exert a harmful effect on proteins, lipids, and nucleic acids. Viral oncogenes E5, E6, and E7 are involved in the development of chronic inflammation through various mechanisms. In addition, HPV may interfere with redox homeostasis of host cells, inducing OS which may be involved in the persistence of the infection and play a certain role in viral integration and promotion of carcinogenesis. Knowledge regarding the interplay between chronic inflammation and OS in the pathogenesis of HPV infection and HPV-induced carcinogenesis has important consequences on the development of new therapeutic strategies.
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3.
Airway Epithelial Differentiation and Mucociliary Clearance.
Whitsett, JA
Annals of the American Thoracic Society. 2018;(Suppl 3):S143-S148
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Abstract
The lung is continuously exposed to particles, toxicants, and microbial pathogens that are cleared by a complex mechanical, innate, and acquired immune system. Mucociliary clearance, mediated by the actions of diverse conducting airway and submucosal gland epithelial cells, plays a critical role in a multilayered defense system by secreting fluids, electrolytes, antimicrobial and antiinflammatory proteins, and mucus onto airway surfaces. The mucociliary escalator removes particles and pathogens by the mechanical actions of cilia and cough. Abnormalities in mucociliary clearance, whether related to impaired fluid secretion, ciliary dysfunction, lack of cough, or the disruption of epithelial cells lining the respiratory tract, contribute to the pathogenesis of common chronic pulmonary disorders. Although mucus and other airway epithelial secretions play a critical role in protecting the lung during acute injury, impaired mucus clearance after chronic mucus hyperproduction causes airway obstruction and infection, which contribute to morbidity in common pulmonary disorders, including chronic obstructive pulmonary disease, asthma, idiopathic pulmonary fibrosis, cystic fibrosis, bronchiectasis, and primary ciliary dyskinesia. In this summary, the molecular and cellular mechanisms mediating airway mucociliary clearance, as well as the role of goblet cell metaplasia and mucus hyperproduction, in the pathogenesis of chronic respiratory diseases are considered.
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4.
Mitochondrial function - gatekeeper of intestinal epithelial cell homeostasis.
Rath, E, Moschetta, A, Haller, D
Nature reviews. Gastroenterology & hepatology. 2018;(8):497-516
Abstract
The intestinal epithelium is a multicellular interface in close proximity to a dense microbial milieu that is completely renewed every 3-5 days. Pluripotent stem cells reside at the crypt, giving rise to transient amplifying cells that go through continuous steps of proliferation, differentiation and finally anoikis (a form of programmed cell death) while migrating upwards to the villus tip. During these cellular transitions, intestinal epithelial cells (IECs) possess distinct metabolic identities reflected by changes in mitochondrial activity. Mitochondrial function emerges as a key player in cell fate decisions and in coordinating cellular metabolism, immunity, stress responses and apoptosis. Mediators of mitochondrial signalling include molecules such as ATP and reactive oxygen species and interrelate with pathways such as the mitochondrial unfolded protein response (MT-UPR) and AMP kinase signalling, in turn affecting cell cycle progression and stemness. Alterations in mitochondrial function and MT-UPR activation are integral aspects of pathologies, including IBD and cancer. Mitochondrial signalling and concomitant changes in metabolism contribute to intestinal homeostasis and regulate IEC dedifferentiation-differentiation programmes in the context of diseases, suggesting that mitochondrial function as a cellular checkpoint critically contributes to disease outcome. This Review highlights mitochondrial function and MT-UPR signalling in epithelial cell stemness, differentiation and lineage commitment and illustrates mitochondrial function in intestinal diseases.
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5.
An Overview of Non-Neural Sources of Calcitonin Gene-Related Peptide.
Hu, R, Li, YJ, Li, XH
Current medicinal chemistry. 2016;(8):763-73
Abstract
Calcitonin gene-related peptide (CGRP) is extensively distributed throughout the central and peripheral nervous systems and has been shown to be a 37 amino acid multifunctional neuropeptide involved in a wide range of physiological and pathological processes. Recently, there is increasing evidence suggesting that CGRP also exists in non-nerve cells, such as epithelial cells, endothelial cells, endothelial progenitor cells (EPCs), T lymphocytes, B lymphocytes, peripheral blood mononuclear cells (PBMCs), and adipocytes. The existence of CGRP in non-neural tissue is of great importance to the regulation of multiple physiological and pathological processes via different pathways, especially through an autocrine/paracrine mode. This review integrates evidence from recent developments and aims to provide novel insights into non-neural sources of CGRP and its effects on physiological and pathological processes.
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6.
Aluminium and the human breast.
Darbre, PD
Morphologie : bulletin de l'Association des anatomistes. 2016;(329):65-74
Abstract
The human population is exposed to aluminium (Al) from diet, antacids and vaccine adjuvants, but frequent application of Al-based salts to the underarm as antiperspirant adds a high additional exposure directly to the local area of the human breast. Coincidentally the upper outer quadrant of the breast is where there is also a disproportionately high incidence of breast cysts and breast cancer. Al has been measured in human breast tissues/fluids at higher levels than in blood, and experimental evidence suggests that at physiologically relevant concentrations, Al can adversely impact on human breast epithelial cell biology. Gross cystic breast disease is the most common benign disorder of the breast and evidence is presented that Al may be a causative factor in formation of breast cysts. Evidence is also reviewed that Al can enable the development of multiple hallmarks associated with cancer in breast cells, in particular that it can cause genomic instability and inappropriate proliferation in human breast epithelial cells, and can increase migration and invasion of human breast cancer cells. In addition, Al is a metalloestrogen and oestrogen is a risk factor for breast cancer known to influence multiple hallmarks. The microenvironment is established as another determinant of breast cancer development and Al has been shown to cause adverse alterations to the breast microenvironment. If current usage patterns of Al-based antiperspirant salts contribute to causation of breast cysts and breast cancer, then reduction in exposure would offer a strategy for prevention, and regulatory review is now justified.
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7.
Inflammation and the Intestinal Barrier: Leukocyte-Epithelial Cell Interactions, Cell Junction Remodeling, and Mucosal Repair.
Luissint, AC, Parkos, CA, Nusrat, A
Gastroenterology. 2016;(4):616-32
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Abstract
The intestinal tract is lined by a single layer of columnar epithelial cells that forms a dynamic, permeable barrier allowing for selective absorption of nutrients, while restricting access to pathogens and food-borne antigens. Precise regulation of epithelial barrier function is therefore required for maintaining mucosal homeostasis and depends, in part, on barrier-forming elements within the epithelium and a balance between pro- and anti-inflammatory factors in the mucosa. Pathologic states, such as inflammatory bowel disease, are associated with a leaky epithelial barrier, resulting in excessive exposure to microbial antigens, recruitment of leukocytes, release of soluble mediators, and ultimately mucosal damage. An inflammatory microenvironment affects epithelial barrier properties and mucosal homeostasis by altering the structure and function of epithelial intercellular junctions through direct and indirect mechanisms. We review our current understanding of complex interactions between the intestinal epithelium and immune cells, with a focus on pathologic mucosal inflammation and mechanisms of epithelial repair. We discuss leukocyte-epithelial interactions, as well as inflammatory mediators that affect the epithelial barrier and mucosal repair. Increased knowledge of communication networks between the epithelium and immune system will lead to tissue-specific strategies for treating pathologic intestinal inflammation.
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8.
Apical iodide efflux in thyroid.
Fong, P
Vitamins and hormones. 2015;:33-62
Abstract
Thyroid follicular epithelial cells produce thyroxine (T4) and its physiologically active derivative, 3,3',5-triiodothyronine (T3), hormones that regulate critical developmental and metabolic functions. In order for the thyroid to form hormone precursor, iodide, the defining element in thyroid hormone, must cross both blood-facing and luminal sides of the follicular epithelium. The pathway for uptake from blood is well understood, but the mechanism(s) that enable iodide to cross the luminally facing apical membrane remain obscure. This chapter considers the physiological properties of several molecularly characterized anion transport proteins, all of which potentially contribute to the overall mechanism of apical iodide efflux.
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Function and repair of dental enamel - Potential role of epithelial transport processes of ameloblasts.
Varga, G, Kerémi, B, Bori, E, Földes, A
Pancreatology : official journal of the International Association of Pancreatology (IAP) ... [et al.]. 2015;(4 Suppl):S55-60
Abstract
The hardest mammalian tissue, dental enamel is produced by ameloblasts, which are electrolyte-transporting epithelial cells. Although the end product is very different, they show many similarities to transporting epithelia of the pancreas, salivary glands and kidney. Enamel is produced in a multi-step epithelial secretory process that features biomineralization which is an interplay of secreted ameloblast specific proteins and the time-specific transport of minerals, protons and bicarbonate. First, "secretory" ameloblasts form the entire thickness of the enamel layer, but with low mineral content. Then they differentiate into "maturation" ameloblasts, which remove organic matrix from the enamel and in turn further build up hydroxyapatite crystals. The protons generated by hydroxyapatite formation need to be buffered, otherwise enamel will not attain full mineralization. Buffering requires a tight pH regulation and secretion of bicarbonate by ameloblasts. The whole process has been the focus of many immunohistochemical and gene knock-out studies, but, perhaps surprisingly, no functional data existed for mineral ion transport by ameloblasts. However, recent studies including ours provided a better insight for molecular mechanism of mineral formation. The secretory regulation is not completely known as yet, but its significance is crucial. Impairing regulation retards or prevents completion of enamel mineralization and results in the development of hypomineralized enamel that easily erodes after dental eruption. Factors that impair this function are fluoride and disruption of pH regulators. Revealing these factors may eventually lead to the treatment of enamel hypomineralization related to genetic or environmentally induced malformation.
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10.
Molecular biology of endometriosis: from aromatase to genomic abnormalities.
Bulun, SE, Monsivais, D, Kakinuma, T, Furukawa, Y, Bernardi, L, Pavone, ME, Dyson, M
Seminars in reproductive medicine. 2015;(3):220-4
Abstract
Endometriosis has been initially described as the presence of ectopic endometrial tissue on pelvic organs or in extrapelvic sites; and this has been used as its key pathologic feature ever since. Endometriosis responds to fluctuations in estrogen and progesterone by growth and inflammation, leading to pain aggravated by menses. It was proposed that pelvic endometriosis primarily originate from retrograde menstruation of a critical number of eutopic endometrial cells with stem characteristics. This postulate is supported by the molecular defects found in ectopic endometriotic tissue. Genome-wide differences in CpG methylation between eutopic endometrial and endometriotic stromal cells are present. Defective CpG methylation affecting several genes that encode key transcription factors such as GATA6, steroidogenic factor-1, and estrogen receptor-β in endometriosis gives rise to overproduction of local estrogen and prostaglandins and suppression of progesterone receptor. Progesterone receptor deficiency leads to progesterone resistance, resulting in decreased retinol uptake and retinoic acid production and altered retinoic acid action. These molecular defects collectively give rise to poor cellular differentiation, enhanced survival, and increased inflammation, which are the biological hallmarks of endometriotic tissue.