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Gut Microbiota—Specific Food Design
Published in Megh R. Goyal, Preeti Birwal, Santosh K. Mishra, Phytochemicals and Medicinal Plants in Food Design, 2022
Aparna V. Sudhakaran, Himanshi Solanki
The function of gut barrier includes three major protective lines: (1) colonization resistance by a biological barrier-resident intestinal microflora against pathogens, (2) immune barrier by gut associated lymph tissue, and (3) the cells in lamina propra. The mechanical barrier consists of the closed epithelial cells of the intestines and the capillary endothelial cells. Special structures called “Tight junctions” connect the cells and limit ions, molecules, and cells moving through paracellular space [3]. The mucus layer in the intestine is a system for shielding the epithelial and luminal luminary cells from direct contact. The bowel cells secrete the mucin glycoprotein that in turn provides the organism with nutrition. Mucosal glycosylation patterns, both on the cell surface and subcellular can also be modulated by the gut microbiota. The structural development of the gut mucosa was influenced by the gut microbiota by inducing the transcription factor angiogenin-3 [36]. The barrier integrity is maintained by the Trefoil factor and the resistin-like molecule secreted by goblet cells [36]. The intestinal barrier is compromised during several diseases leading to an increased level of bacterial transloca-tions, further leading to systemic inflammations.
The patient with acute neurological problems
Published in Peate Ian, Dutton Helen, Acute Nursing Care, 2020
The blood–brain barrier is an important structure that prevents harmful substances in the bloodstream from entering brain tissue. The blood–brain barrier has two main components: a thick capillary basement membrane and tight junctions between the endothelial cells of the capillaries. Capillaries in other parts of the body have gaps between the endothelial cells that allow substances to diffuse across the capillary wall and enter the interstitial space. Tight junctions in brain capillaries and the thick basement membrane prevents diffusion, the brain relies on astrocytes to control the movement of substances from blood to brain. The foot processes of astrocytes press tightly against the endothelial wall of brain capillaries, secreting chemicals that control the permeability of the capillary. This structure is semipermeable to some water-soluble substances like glucose, but not others, for example, proteins and antibiotics. However, it is permeable to fat-soluble substances, e.g., oxygen, carbon dioxide, alcohol and most anaesthetic agents (Tortora and Derrickson 2017). The blood–brain barrier is affected by trauma and inflammation and can malfunction.
Epithelial Cells
Published in Bruce S. Bochner, Adhesion Molecules in Allergic Disease, 2020
Tight junctions seal the apical aspects of the epithelial cell, eliminating the intercellular space to create a regulated paracellular barrier to the movement of water, solutes, and leukocytes (52). Ultrastructurally, freeze-fracture studies show that tight junctions resemble a complex network of linearly arranged strands (46). Biochemically, several proteins have been associated with tight junctions. These include E-cadherin (see below), ZO-1, a 220-kD protein that requires the availability of calcium and cell contact in order to be present in the plasma membrane (53), and ZO-2, a 160-kD protein (54). Within the cytoplasmic plaque of the tight junction, ZO-1 and ZO-2 are bound to each other (55), and to an as yet unidentified 130-kD protein (52). Cingulin, a dimeric protein that consists of two 108-kD polypeptide chains, also is found at the cytoplasmic side of the cell membrane (56). Furuse et al. (57) have recently identified a transmembrane protein called occludin, which may function as the sealing protein; this work was done, however, in cell membranes derived from chicken liver, and occludin has not yet been shown in respiratory tissues. Occludin is bound on the cytoplasmic surface to the plaque proteins ZO-1 and ZO-2, which in turn are linked to cytoskeletal filaments.
Claudin-18.2 as a therapeutic target in cancers: cumulative findings from basic research and clinical trials
Published in Tissue Barriers, 2022
Daisuke Kyuno, Akira Takasawa, Kumi Takasawa, Yusuke Ono, Tomoyuki Aoyama, Kazufumi Magara, Yuna Nakamori, Ichiro Takemasa, Makoto Osanai
Tight junction molecules have intercellular adhesion functions in all cell types. Recently, the dynamics of these proteins in cancer cells have attracted attention. Epithelial cells are held together by several major classes of intracellular junctions, and adherens and tight junctions play essential roles in the development and maintenance of epithelial cells. Tight junctions are typically located on the apical side of epithelial cells, and their components interact with those of neighboring cells. Tight junction proteins are often dysfunctional or altered in various types of cancer cells, and their controlled paracellular permeation and polarity are lost in cancer cells1. Altered tight junction proteins also modulate cytoskeletal elements and signaling molecules bound to these proteins, resulting in the loss of regulated cell migration and proliferation.2
Distribution and translocation of micro- and nanoplastics in fish
Published in Critical Reviews in Toxicology, 2021
Cuizhu Ma, Qiqing Chen, Jiawei Li, Bowen Li, Weiwenhui Liang, Lei Su, Huahong Shi
Previous studies suggest that particles enter the intercellular space, and then translocate into the blood or stay in the tissue intercellular space. In vitro researches indicate that PS short chains (25 monomers) incorporate in the membrane and alter the cell membrane structure and dynamics (Bochicchio et al. 2022). Von Moos et al. (2012) detected particles in the blood lacunae of the gills and in the areas of lamellar tight junctions, where two cells are closely connected. The tight junction is useful to close the gap between adjacent cells and prevent foreign materials from entering tissue through paracellular penetration. These so-called tight junctions are found elsewhere in the circulatory system, intestine epithelial cells, and testis, but they are especially tight in the brain. Researchers design antibodies or antibody fragments that bind to receptors on the endothelial cells to safely penetrate BBB’s defenses and to reach the brain (Shen 2017). Laboratory studies have indicated that NPs (39.4–180 nm) enter brain tissues (Kashiwada 2006; Mattsson et al. 2017; Zhang et al. 2019). Nanoparticles are either negatively charged on the surface, or capable of binding to receptors on the cell surface in order to cross the tissue barriers (Sweeney et al. 2019), but we still do not know how environmental NPs open the tight connections and penetrate the BBB.
Airway tight junctions as targets of viral infections
Published in Tissue Barriers, 2021
Debra T. Linfield, Andjela Raduka, Mahyar Aghapour, Fariba Rezaee
As mentioned above, HRV is a significant cause of asthma exacerbations.121 Azithromycin, a macrolide antibiotic used to treat many pulmonary bacterial infections, has been shown to reduce the severity of an acute asthma exacerbation by inhibiting Intercellular Adhesion Molecule 1 (ICAM-1), a receptor for HRV.124 It may help in reestablishing the AJC barrier following infection. In primary AECs, azithromycin induced intracellular localization of claudin-1 and −4, occludin, and JAM-A.125 There were no effects on E-cadherin. Of note, improved TEER following azithromycin administration suggests that this processing of TJ proteins helps decrease permeability and increase cell integrity, thereby potentially preventing entry of viral infections.124,125 Further studies are warranted to elucidate its mechanism in therapeutic strategies and its effect on the tight junction barrier.