Paneth cell
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2008-05-28T18:20:19Z
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[[Image:Paneth cells.JPG|thumb|250px|Paneth cells]]
'''Paneth cells''' provide host defense against [[microbes]] in the [[small intestine]]. They are functionally similar to [[Neutrophil granulocyte|neutrophils]]. When exposed to [[bacteria]] or bacterial [[antigen]]s, Paneth cells secrete a number of [[antimicrobial]] [[molecule]]s into the [[lumen]] of the [[crypt (anatomy)|crypt]], thereby contributing to maintenance of the [[gastrointestinal barrier]]. Paneth cells are named after [[Joseph Paneth]] (1857–1890), Austrian physician.
==Stem cells==
Small intestinal crypts house stem [[cell (biology)|cell]]s that serve to constantly replenish [[epithelial cells]] that die and are lost from the [[villi]].
Protection of these [[stem cells]] is essential for long-term maintenance of the intestinal [[epithelium]], and the location of Paneth cells adjacent to stem cells suggests that they play a critical role in defending epithelial cell renewal.
==Secretions==
===Defensins===
The principal defense molecules secreted by Paneth cells are [[defensin|alpha-defensins]], also known as [[cryptdin]].<ref> {{cite journal | author = Wilson C, Ouellette A, Satchell D, Ayabe T, López-Boado Y, Stratman J, Hultgren S, Matrisian L, Parks W | title = Regulation of intestinal alpha-defensin activation by the metalloproteinase matrilysin in innate host defense. | journal = Science | volume = 286 | issue = 5437 | pages = 113–7 | year = 1999 | pmid = 10506557 | doi = 10.1126/science.286.5437.113}}</ref> These [[peptides]] have [[hydrophobic]] and positively-charged domains that can interact with [[phospholipids]] in [[cell membranes]]. This structure allows defensins to insert into membranes, where they interact with one another to form pores that disrupt membrane function, leading to cell lysis. Due to the higher concentration of negatively-charged phospholipids in bacterial than vertebrate [[cell membrane]]s, defensins preferentially bind to and disrupt bacterial cells, sparing the cells they are functioning to protect.<ref>{{cite journal | author = Ayabe T, Satchell D, Wilson C, Parks W, Selsted M, Ouellette A | title = Secretion of microbicidal alpha-defensins by intestinal Paneth cells in response to bacteria. | journal = Nat Immunol | volume = 1 | issue = 2 | pages = 113–8 | year = 2000 | pmid = 11248802 | doi = 10.1038/77783}}</ref>
Paneth cells are stimulated to secrete defensins when exposed to bacteria (both [[Gram-positive bacteria | Gram positive]] and [[Gram-negative bacteria | negative]] types) or such bacterial products as [[lipopolysaccharide]], [[muramyl dipeptide]] and [[lipid A]].
===Other secretions===
In addition to defensins, Paneth cells secrete [[lysozyme]] and [[phospholipase A2]], both of which have clear [[antimicrobial]] activity. This battery of secretory molecules gives Paneth cells a potent arsenal against a broad spectrum of agents, including bacteria, [[fungi]] and even some enveloped [[virus]]es.
==References==
<references/>
==Further reading==
* {{cite journal | author = Ganz T | title = Defensins and host defense. | journal = Science | volume = 286 | issue = 5439 | pages = 420–1 | year = 1999 | pmid = 10577203 | doi = 10.1126/science.286.5439.420}}
* {{cite journal | author = Ganz T | title = Paneth cells--guardians of the gut cell hatchery. | journal = Nat Immunol | volume = 1 | issue = 2 | pages = 99–100 | year = 2000 | pmid = 11248797 | doi = 10.1038/77884}}
*
==External links==
* {{MeshName|Paneth+Cells}}
* {{BUHistology|11604loa}} - "Endocrine System: duodenum, enteroendocrine cells"
* {{BUHistology|11606loa}} - "Digestive System: Alimentary Canal - duodenum, paneth cells"
* [http://www.vivo.colostate.edu/hbooks/pathphys/digestion/smallgut/paneth.html Overview and diagram at colostate.edu]
* [http://meded.ucsd.edu/hist-img-bank/chapter_6/Slide_94_crypts_duodenum/pages/b.6.94.1.5.htm Histology at ucsd.edu]
{{Gastrointestinal physiology}}
[[Category:Cells]]
[[Category:Human cells]]
[[Category:Gastroenterology]]
{{anatomy-stub}}
[[de: Panethzelle]]
[[ja:パネート細胞]]
[[sv: panethceller]]
[[zh:潘氏细胞]]