Cell ??-Defensin Synthesis and Function.

and gene structure of cryptdin 4, a differentially expressed mouse Paneth cell alpha-defensin.
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OuellettePaneth cell alpha-defensin synthesis and function.

Epithelial cells of the mucosa form a barrier between the gut lumen and underlying host tissues. In addition to this barrier function, epithelial cells perform a key role in host innate and adaptive responses, secreting of a wide range of immunomodulatory molecules [, ]. Paneth cells are specialized ileal epithelial cells located at the crypt base in close vicinity of multipotent stem cells and fulfill a crucial role in innate immunity. They are a source of several antimicrobial enzymes such as lysozyme and group IIA phospholipase A2 (PLA2) as well as the antimicrobial peptides human defensin 5 and 6 (HD-5 and HD-6), which are stored in secretory granules [, ].

19/12/2017 · Paneth Cell ??-Defensin Synthesis and Function
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cell alpha-defensin synthesis and function.

The mucosal epithelium secretes a variety of antimicrobial peptides that act as part of the innate immune system to protect against invading microbes. Here, we describe the functional properties of human defensin 5, the major antimicrobial peptide produced by Paneth cells in the ileum, in relation to its structure. The antimicrobial activity of human defensin 5 against Escherichia coli proved to be independent of its structure, whereas the unstructured peptide showed greatly reduced antimicrobial activity against Staphylococcus aureus. We find that human defensin 5 binds to the cell membrane of intestinal epithelial cells and induced secretion of the chemokine IL-8 in a concentration- and structure-dependent fashion. Incubation of human defensin 5 in the presence of tumor necrosis factor alpha further increased IL-8 secretion synergistically, suggesting that human defensin 5 may act as a regulator of the intestinal inflammatory response.

Paneth cell alpha-defensin synthesis and function
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Defensins are 2-6 kDa, cationic, microbicidal peptides active against many Gram-negative and Gram-positive bacteria, fungi, and enveloped viruses [()], containing three pairs of intramolecular disulphide bonds. On the basis of their size and pattern of disulphide bonding, mammalian defensins are classified into alpha, beta and theta categories. Alpha-defensins, which have been identified in humans, monkeys and several rodent species, are particularly abundant in neutrophils, certain macrophage populations and Paneth cells of the small intestine. Every mammalian species explored thus far has beta-defensins. In cows, as many as 13 beta-defensins exist in neutrophils. However, in other species, beta-defensins are more often produced by epithelial cells lining various organs (e.g. the epidermis, bronchial tree and genitourinary tract). Theta-defensins are cyclic and have so far only been identified in primate phagocytes.

Paneth cell alpha-defensin synthesis ..
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