User:Immcarl17/sandbox

Jan 9th: Taking my second training module and learning how to edit in the Wikipedia Sand box feature. Sandbox is a feature that allows users to practice making edits on a practice page before making edits to live articles.

Feb 17th:

This is the current lead section from the wikipedia page for M cells. I will be updated it to include a few more sentences to a whole paragraph about the function, morphology, and development of these cells. I have also added a citation for the last sentence on the current lead section.

Existing lead section Microfold cells (or M cells) are found in the follicle-associated epithelium of the Peyer's patch as well as in bronchus-associated lymphoid tissue (BALT). They transport organisms and particles from the gut lumen to immune cells across the epithelial barrier, and thus are important in stimulating mucosal immunity.

Unlike their neighbouring cells, they have the unique ability to take up antigen from the lumen of the small intestine via endocytosis or phagocytosis, and then deliver it via transcytosis to dendritic cells (an antigen presenting cell) and lymphocytes (namely T cells) located in a unique pocket-like structure on their basolateral side [citation needed].

Lead section (with my edits) Microfold cells ( M cells or intestinal membranous cells) are found in the follicle-associated epithelium (FAE) of the Peyer's patch and the gut-associated lymphoid tissue (GALT). These cells initiate mucosal immune responses on the apical membrane of the M cells and allow for transport of microbes and particles from the gut lumen into immune cells across the epithelial barrier.

M cells express the protease cathepsin E, similar to other antigen presenting cells. Unlike their neighbouring cells, M cells have the unique ability to take up antigen from the lumen of the small intestine via endocytosis or phagocytosis, and then deliver it via transcytosis to dendritic cells (another antigen presenting cell) and lymphocytes (namely T cells). This process takes place in a unique pocket-like structure on their basolateral side [5]. Recognition of antigens is done via expression cell surface receptors such as glycoprotein-2 (GP2) that detect and specifically bind to bacteria possessing Type I pili. Cellular prion protein (PrP) has also been identified as an antigen-uptake receptor on the surface of these cels.

M cells lack microvilli and they are characterized by strong cell junction to function as a barrier and thus defense line in the immune system. Despite these characteristics, some antigens are able to infiltrate the M cell barrier and infect the nearby epithelial cells or enter the gut [7].

Morphology Section M cells are distinguished from other intestinal epithelial cells by their morphological differences. They are characterized by short microvilli or lack of these protrusions on the cellsurface. When they present microvilli, they are short, irregular, and present on the apical surface or pocket-like invagination on the basolateral surface of these cells. When they lack microvilli, they are characterized by microfolds, and hence receive their commonly known name. These cells can also be identified by cytoskeletal and extracellular matrix components expressed at the edge of cells or on their cell surfaces, such as actin, villin, cytokeratin, and vimentin [7].

Development Section B cells have been implicated in the developmental of M cells, since they are also localized in high numbers in the follicular-associated epithelium. FAE lacking B cell populations result in a decrease in the number of M cell lining the Peyer's patch [6]. Similarly, a human lymphoma cell line, called Raji cells, are also known to cause transition of adenocarcinoma cells to M cells. Though many studies have shown various cell types directing the differentiation of M cells, the field is at a point of characterizing the molecular pathways that guide M cell differentiation. More recently, through loss-of-function and rescue-phenotype studies, RANKL has been shown to be a receptor activator of NF-κB ligand and play a role in differentiation of M cells [8]. Interestingly, microbes found among existing intestinal epithelium are also known to direct M cell development. For example, the type III secretion system effector protein SopB activates the transition of M cells from enterocytes [9].

5. 6. 7. 8. 9.

Immcarl17 (talk) 05:41, 18 February 2016 (UTC)