Variations in the expression of pili: the effect on adherence of Neisseria meningitidis to human epithelial and endothelial cells

Abstract

The effect of variations in Neisseria meningitidis pili on bacterial interactions with three epithelial cell lines as well as human umbilical vein endothelial cells was studied using a panel of seven strains expressing Class I or Class II pili. Comparison of adherence of piliated and pilus-deficient variants of each strain to epithelial cells suggested that Class I pili may mediate bacterial adherence with all three epithelial cell lines. In contrast, Class II pili of the strains used did not increase bacterial adherence to Hep-2 larynx carcinoma cells, although an increase in adherence to Chang conjunctival and A549 lung carcinoma epithelial cells was observed in the Class II pili-expressing strains. In addition to these interclass functional variations, differences in adherence to epithelial cells were also observed among Class I and Class II strains. Functionally different pilin variants of one Class I strain, MC58, were obtained by single colony isolation. One piliated variant was identified which had concurrently lost the ability to adhere to both Chang and Hep-2 cells ('non-adherent' phenotype; adherence of less than 2 bacteria per cell). In addition, several adherent pilin variants were isolated from non-adherent Pil- and Pil+ bacteria by selection on Chang cells (adherence of 10-25 bacteria per cell). In contrast to epithelial cells, all variant pili, whether of Class I or Class II, adhered to endothelial cells in substantially larger numbers (greater than 50 bacteria per cell) and therefore implied the existence of distinct mechanisms in pilus-facilitated interactions of N. meningitidis with endothelial and epithelial cells.

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

“…The meningococcal capsule is another major surface structure that could hinder intimate contact between Nm and target cells (Virji et al, 1992;de Vries et al, 1996;Hammerschmidt et al, 1996;Hardy et al, 2000). We have previously reported that capsule levels decrease upon cell contact (Deghmane et al, 2000).…”

“…crgA encodes a transcriptional regulator of the LysR family and seems to be involved in the adhesion of Nm to target cells because insertional inactivation of this gene strongly decreases meningococcal adhesion to epithelial cells, particularly during the phase of Nm-cell intimate adhesion (Deghmane et al, 2000). CrgA may be involved in the switch from initial adhesion to intimate adhesion by downregulating bacterial surface structures that hinder intimate adhesion, such as the pili and capsule (Virji et al, 1992;Hammerschmidt et al, 1996;de Vries et al, 1996;Hardy et al, 2000). The aim of this work was to investigate this hypothesis by analysing the effects of CrgA on the production of pili and capsule during interaction between bacteria and cells.…”

Membrane cofactor protein (MCP or CD46) is a cellular pilus receptor for pathogenic Neisseria

“…These data represent the average of three independent experiments. the colonization of epithelial and endothelial cells (Kellogg et al, 1968;Virji et al, 1992). The adherence to epithelial cells is dependent on a pilus adhesin, called PilC, and on variations in the major pilus subunit, PilE (Virji et al, 1992;Nassif et al, 1993;Jonsson et al, 1994;Rudel et al, 1992;1995a,b).…”

“…the colonization of epithelial and endothelial cells (Kellogg et al, 1968;Virji et al, 1992). The adherence to epithelial cells is dependent on a pilus adhesin, called PilC, and on variations in the major pilus subunit, PilE (Virji et al, 1992;Nassif et al, 1993;Jonsson et al, 1994;Rudel et al, 1992;1995a,b). Our previous studies have shown that piliated N. gonorrhoeae bind to a wide variety of human tissues and cell types and that the receptor is sensitive to proteolysis (Jonsson et al, 1994).…”

“…Sequence alterations in PilE of pathogenic Neisseria have profound effects on host and tissue tropism (Virji et al, 1992;Nassif et al, 1993;Jonsson et al, 1994). PilC, a 110-kDa pilus-associated protein, was shown to alter pilus-mediated adhesion to target cells (Rudel et al, 1992).…”