1. Proinflammatory and defense responses in enterocyte- and colonic-like cells and PMNLs after infection with the diarrhea-associated strain C1845.
Proinflammatory and defense responses in enterocyte- and colonic-like cells and PMNLs after infection with the diarrhea-associated strain C1845. The drawing on the left summarizes the observed cellular events. An hDAF-dependent MAPK-, PI3K/Akt-, and HIF-1α-triggered signaling (1) leads to the production of the proinflammatory cytokine IL-8, which promotes the transepithelial migration of PMNLs (2), which in turn promotes the production of proinflammatory cytokines TNF-α and IL-1β (3) and leads to the up-expression of brush border-associated hDAF (4) and basolateral MICA (5) and the abnormal expression of hDAF at the basolateral domain (5). Afa/Dr DAEC interacting with transmigrated PMNLs induces cytotoxic proinflammatory responses and a defense response involving NET-triggered bacterial killing (6). As the result of a host intestinal cell defense response, bacteria attached at the brush border are entrapped by microvilli and killed (7). In addition, bacteria attached at the brush border are extruded from the intestinal cells when the tips of microvilli are shed (7). (A) A high-magnification scanning electron micrograph shows an altered bacterium entrapped by numerous microvilli in Caco-2 cells. (Reprinted from reference 487 with permission of Elsevier.) (B) A high-magnification scanning electron micrograph shows a highly damaged adhering bacterium at a late time of infection. (Reprinted from reference 487 with permission of Elsevier.) (C) A high-magnification scanning electron micrograph shows a bulbous membrane protrusion at the tip of elongated microvilli in close contact with an adhering bacterium. (Reprinted from reference 410.) (D) A high-magnification transmission electron micrograph shows a high number of cell membrane vesicles in close contact with a bacterium that is detached from the brush border. (Reprinted from reference 410.) (E and F) Low- and high-magnification field emission scanning electron micrographs show the NETs expressed by phorbol myristate acetate (PMA)-stimulated PMNL-like PLB-985 cells. (Reprinted from reference 471.) (G and H) Low- and high-magnification field emission scanning electron micrographs show NETs expressed by infected PMNL-like PLB-985 cells and in contact with diarrhea-associated C1845 bacteria. (Reprinted from reference 471.)‏
Alain L. Servin Clin. Microbiol. Rev. 2014; doi: /CMR