PMNs facilitate translocation of platelets across human and mouse epithelium and together alter fluid homeostasis via epithelial cell–expressed ecto-NTPDases
Thomas Weissmüller, Eric L. Campbell, Peter Rosenberger, Melanie Scully, Paul L. Beck, Glenn T. Furuta, Sean P. Colgan
Thomas Weissmüller, Eric L. Campbell, Peter Rosenberger, Melanie Scully, Paul L. Beck, Glenn T. Furuta, Sean P. Colgan
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Research Article Inflammation

PMNs facilitate translocation of platelets across human and mouse epithelium and together alter fluid homeostasis via epithelial cell–expressed ecto-NTPDases

Abstract

Mucosal diseases are often characterized by an inflammatory infiltrate that includes polymorphonuclear leukocytes (PMNs), monocytes, lymphocytes, and platelets. A number of studies have suggested that the interaction of platelets with leukocytes has an essential proinflammatory role. Here, we examined whether platelets migrate across mucosal epithelium, as PMNs are known to do, and whether platelets influence epithelial cell function. Initial studies revealed that human platelets did not efficiently transmigrate across human epithelial cell monolayers. However, in the presence of human PMNs, platelet movement across the epithelium was proportional to the extent of PMN transmigration, and strategies that blocked PMN transmigration diminished platelet movement. Furthermore, platelet-PMN comigration was observed in intestinal tissue derived from human patients with inflammatory bowel disease (IBD). The translocated platelets were found to release large quantities of ATP, which was metabolized to adenosine via a 2-step enzymatic reaction mediated by ecto-nucleotidases, including CD73 and ecto–nucleoside triphosphate diphosphohydrolases (ecto-NTPDases), expressed on the apical membrane of the intestinal epithelial cells. In vitro studies and a mouse model of intestinal inflammation were employed to define a mechanism involving adenosine-mediated induction of electrogenic chloride secretion, with concomitant water movement into the intestinal lumen. These studies demonstrate that ecto-NTPDases are expressed on the apical membrane of epithelial cells and are involved in what we believe to be a previously unappreciated function for platelets in the inflamed intestine, which might promote bacterial clearance under inflammatory conditions.

Authors

Thomas Weissmüller, Eric L. Campbell, Peter Rosenberger, Melanie Scully, Paul L. Beck, Glenn T. Furuta, Sean P. Colgan

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Figure 3

Contribution of epithelial chloride channels to the Cl– secretion response.

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Contribution of epithelial chloride channels to the Cl– secretion respon...
(A) Epithelial electrogenic Cl– secretion in response to increasing concentrations of ATP. Results are pooled from 8 monolayers in each condition and expressed as mean ± SEM. (B) Influence of chloride channel inhibitor NPPB on Isc response elicited by ATP. Results are pooled from 6 monolayers in each condition and results are expressed as mean ± SEM. (C and D) Influence of NPPB on electrogenic Cl– secretion elicited by supernatants from activated PMNs (C) or activated platelets (D). Results are pooled from 9 monolayers and supernatants derived from 3 separate donors in each condition, and results are expressed as mean ± SEM. (E) Polarity of epithelial electrogenic Cl– secretion in response to 10 μM ATP to the apical (AP), basolateral (BL), or apical and basolateral (AP + BL) surfaces of confluent T84 cell monolayers. Data are pooled from 6 monolayers in each condition, and results are expressed as mean ± SEM.