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The Silver Lining
Published in David J. Hackam, Necrotizing Enterocolitis, 2021
Mark R Frey, Misty Good, Steven J. McElroy
Goblet cells are the major secretory cell located in the intestinal epithelium and are responsible for producing trefoil peptides, resistin-like molecule-β, Fcγ binding protein, and mucin (mucus) (85). Intestinal mucus is one of the key components of innate immunity (Figure 39.4) (86). Mucins are large glycoproteins that provide a physical barrier, facilitate removal of adherent bacteria, and aid in host nutrient digestion (87). They are expressed early in development and reach adult levels by 27 weeks of gestation (88). However, the mucus produced by immature intestinal tracts has different viscosity (89), buoyancy, and carbohydrate composition (90) than in adults.
Control of the Large Bowel Microflora
Published in Michael J. Hill, Philip D. Marsh, Human Microbial Ecology, 2020
Bohumil S. Drasar, April K. Roberts
During the fust day of life both bacteria and additional nutrients from the milk reach the large intestine where a rich microflora develops. The epithelium of the large intestine is lined by a layer of mucin that almost fills the lumen of the colon.23 This mucin acts as a lubricant, as a barrier to organisms trying to reach the epithelial cells, and as a surface to stabilize the fecal community. Using electron microscopy, bacteria have been visualized in and under the mucus surface in man and animals.23–25
Secreted effectors of the innate mucosal barrier
Published in Phillip D. Smith, Richard S. Blumberg, Thomas T. MacDonald, Principles of Mucosal Immunology, 2020
Michael A. McGuckin, Andre J. Ouellette, Gary D. Wu
Nonstructural components of the mucosal barrier, including mucus produced by goblet cells and antimicrobial peptides produced by Paneth cells, play a fundamental role in mucosal protection. Goblet and Paneth cells arise from steM cell progenitors through intricate developmental pathways involving both Wnt and Notch signaling. Mucus, produced by goblet cells, protects the intestinal mucosal surface through its biophysical properties as well as its effects on luminal bacteria. The composition of mucus includes various mucins that are complex glycoproteins. Paneth cell products include antimicrobial peptides such as defensins, which influence the composition of the gut microbiota. Together, mucins and antimicrobial peptides form a secreted mucosal barrier that provides protection against an array of microbes. Components of both the innate and adaptive mucosal immune systems contribute to goblet cell and Paneth cell regulation in response to specific environmental challenges. Goblet cells are also involved in antigen transfer to antigen-presenting cells establishing appropriate regulatory and adaptive mucosal immune responses. Defects in either goblet or Paneth cells can lead to a disruption of the secreted mucosal barrier and thus contribute to the pathogenesis of mucosal diseases such as inflammatory bowel disease and necrotizing enterocolitis.
Prebiotic oligofructose protects against high-fat diet-induced obesity by changing the gut microbiota, intestinal mucus production, glycosylation and secretion
Published in Gut Microbes, 2022
Paola Paone, Francesco Suriano, Ching Jian, Katri Korpela, Nathalie M. Delzenne, Matthias Van Hul, Anne Salonen, Patrice D. Cani
It has been observed that during obesity and metabolic disorders the gut microbiota composition is different and this is associated with gut barrier dysfunction.3,4 Among the components of the gut barrier, the mucus layer is critical and hence has raised more attention in recent years. The mucus layer is the first line of protection of the gastrointestinal tract and the interface of communication between the gut microbiota and the host.5 It is produced and secreted by the goblet cells and mainly composed of specific proteins called mucins. Mucins are heavily glycosylated proteins with different glycans, often representing more than 80% of the mucin mass.5 The enzymes responsible for the mucin glycosylation are called glycosyltransferases and are specific for each glycan residue and for precise positions. The mucins are classified as secreted and transmembrane and the most important component of the mucus layer is the secreted mucin 2 (Muc2).
Impact of quorum sensing signaling molecules in gram-negative bacteria on host cells: current understanding and future perspectives
Published in Gut Microbes, 2022
Yingping Xiao, Huicong Zou, Jingjing Li, Tongxing Song, Wentao Lv, Wen Wang, Zhenyu Wang, Shiyu Tao
The gut<apos;>s first line of defense against invasion of pathogenic microorganisms and harmful metabolites is the mucus layer that covers the outer side of intestinal epithelial cells.145,146 The main component of the mucus layer is mucin, which is synthesized and secreted by intestinal goblet cells and acts as a barrier covering the entire intestinal surface.147–149 Studies have shown that the absence or abnormal expression of mucins can lead to intestinal diseases, whereas pathogenic microorganisms and some of their metabolites can induce abnormal expression of mucins.150–152 As for the influence of AHL on the intestinal mucus barrier, we first established a co-culture model of 3-oxo-C12-HSL and intestinal goblet cells, and demonstrated that 3-oxo-C12-HSL induced an imbalance of intestinal goblet cell homeostasis by causing mitochondrial swelling, mitochondrial membrane potential depolarization, mitochondrial dysfunction, and cell apoptosis. Furthermore, 3-oxo-C12-HSL inhibits mucin synthesis and sulfuration, ultimately destroying the intestinal mucus barrier. On this basis, the 3-oxo-C12-HSL/PON2 specific inhibitor/intestinal goblet cell co-culture model was established, and it was found that 3-oxo-C12-HSL induced a series of harmful biological effects in a PON2-dependent manner, eventually resulting in the disorder of intestinal goblet cell structure and function 85,153,154 (Figure 3).
Keeping an ‘eye’ on ocular GVHD
Published in Clinical and Experimental Optometry, 2022
Jelena Marie Kezic, Steven Wiffen, Mariapia Degli-Esposti
More recently, Royer et al.80 reported the loss of corneal sensation with a reduction in corneal nerve integrity and decreased nerve density 26 days after bone marrow transplantation in a mouse model of GVHD. These findings are consistent with the reported loss of corneal sub-basal nerves in patients with chronic GVHD.24,81 This is an important observation given the central role of the sub-basal nerve plexus in reflex tear production and low sub-basal nerve density has also been observed in patients with dry eye disease.46,47 Another study demonstrated a significant reduction in the thickness of the glycocalyx on the corneal surface in mice with GVHD 8 weeks after allo-transplantation.70 Since the mucin-rich glycocalyx contributes to the maintenance of a healthy tear film, this reduced level of mucins on the corneal surface in GVHD is likely to contribute to loss of lubrication and hydration of the ocular surface. Indeed, reduced levels of mucins have been reported in patients with dry eye disease.82