Type IV pili of pathogenic Neisseriae elicit cortical plaque formation in epithelial cells

Abstract

SummaryThe pathogenic Neisseriae Neisseria meningitidis and Neisseria gonorrhoeae, initiate colonization by attaching to host cells using type IV pili. Subsequent adhesive interactions are mediated through the binding of other bacterial adhesins, in particular the Opa family of outer membrane proteins. Here, we have shown that pilus-mediated adhesion to host cells by either meningococci or gonococci triggers the rapid, localized formation of dramatic cortical plaques in host epithelial cells. Cortical plaques are enriched in both components of the cortical cytoskeleton and a subset of integral membrane proteins. These include: CD44v3, a heparan sulphate proteoglycan that may serve as an Opa receptor; EGFR, a receptor tyrosine kinase; CD44 and ICAM-1, adhesion molecules known to mediate inflammatory responses; f-actin; and ezrin, a component that tethers membrane components to the actin cytoskeleton. Genetic analyses reveal that cortical plaque formation is highly adhesin specific. Both pilE and pilC null mutants fail to induce cortical plaques, indicating that neisserial type IV pili are required for cortical plaque induction. Mutations in pilT, a gene required for pilus-mediated twitching motility, confer a partial defect in cortical plaque formation. In contrast to type IV pili, many other neisserial surface structures are not involved in cortical plaque induction, including Opa, Opc, glycolipid GgO 4 -binding adhesins, polysialic acid capsule or a particular lipooligosaccharide variant. Furthermore, it is shown that type IV pili allow gonococci to overcome the inhibitory effect of heparin, a soluble receptor analogue, on gonococcal invasion of Chang and A431 epithelial cells. These and other observations strongly suggest that type IV pili play an active role in initiating neisserial infection of the mucosal surface in vivo. The functions of type IV pili and other neisserial adhesins are discussed in the specific context of the mucosal microenvironment, and a multistep model for neisserial colonization of mucosal epithelia is proposed.

Influence of type IV pilus retraction on the architecture of the Neisseria gonorrhoeae-infected cell cortex

“…The A431 human epidermoid carcinoma cell line (a kind gift of S. Schmid) was used for these studies. These cells have been used previously for neisseria infection studies and their maintenance has been described (Larson et al, 2002;Merz et al, 1999). Briefly, cells were maintained in Dulbecco's Modified Eagle's Medium (DMEM; Mediatech) supplemented with 10 % heat-inactivated fetal bovine serum (FBS; Gibco), and incubated at 37 uC, 5 % CO 2 .…”

“…Tfp retraction recruits host cell components to the cortex beneath adhered microcolonies. These cortical plaques are enriched in cytoskeletal and signalling proteins (Edwards et al, 2000;Lee et al, 2005;Merz et al, 1999;Weyand et al, 2006), some of which have been shown to play a role in invasion (Lee et al, 2005;Shaw & Falkow, 1988). The relationship between the cortical plaque and the microcolony is dynamic.…”

Down‐regulation of pili and capsule of Neisseria meningitidis upon contact with epithelial cells is mediated by CrgA regulatory protein

“…CD46 may transduce a signal to the cell via its cytoplasmic tail. Indeed, in a recent study, neisserial type IV pili were reported to be required for cortical plaque formation in epithelial cells (Merz et al, 1999). These plaques are enriched in cellular components involved in bacterial adhesion to target cells such as phosphotyrosine, actin and ezrin (Merz and So, 1997;Merz et al, 1999).…”

“…Indeed, in a recent study, neisserial type IV pili were reported to be required for cortical plaque formation in epithelial cells (Merz et al, 1999). These plaques are enriched in cellular components involved in bacterial adhesion to target cells such as phosphotyrosine, actin and ezrin (Merz and So, 1997;Merz et al, 1999). Once intimate adhesion is achieved, the surfaces of heavily infected cells appear to be denuded of microvilli (Merz and So, 1997;Deghmane et al, 2000).…”

Pili de type IV

“…Mais il ne faut pas oublier que les humaines. Nombre de modifications des cellules humaines associées à l'infection par Neisseria ne se font plus [7,8]. L'expression génique des cellules humaines en réponse à l'infection est aussi fortement modifiée en présence ou en l'absence de force mécanique [9].…”