Article

Factor H binding to PspC of Streptococcus pneumoniae increases adherence to human cell lines in vitro and enhances invasion of mouse lungs in vivo.

Department of Microbiology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216, USA.
Infection and Immunity (impact factor: 4.16). 09/2007; 75(8):4082-7. DOI:10.1128/IAI.00474-07
Source: PubMed

ABSTRACT Pneumococcal surface protein C (PspC) binds to both human secretory immunoglobulin A (sIgA) and complement factor H (FH). FH, a regulator of the alternative pathway of complement, can also mediate adherence of different host cells. Since PspC contributes to adherence and invasion of host cells, we hypothesized that the interaction of PspC with FH may also mediate adherence of pneumococci to human cells. In this study, we investigated FH- and sIgA-mediated pneumococcal adherence to human cell lines in vitro. Adherence assays demonstrated that preincubation of Streptococcus pneumoniae D39 with FH increased adherence to human umbilical vein endothelial cells (HUVEC) 5-fold and to lung epithelial cells (SK-MES-1) 18-fold, relative to that of D39 without FH on the surface. The presence of sIgA enhanced adherence to SK-MES-1 6-fold and to pharyngeal epithelial cells (Detroit 562) 14-fold. Furthermore, sIgA had an additive effect on adherence to HUVEC; specifically, preincubation of D39 with both FH and sIgA led to a 21-fold increase in adherence. Finally, using a mouse model, we examined the significance of the FH-PspC interaction in pneumococcal nasal colonization and lung invasion. Mice intranasally infected with D39 preincubated with FH had increased bacteremia and lung invasion, but they had similar levels of nasopharyngeal colonization compared to that of mice challenged with D39 without FH.

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Keywords

adherence
 
Adherence assays
 
D39 preincubated
 
different host cells
 
factor H
 
FH-PspC interaction
 
host cells
 
human cell lines
 
human cells
 
human secretory immunoglobulin
 
human umbilical vein endothelial cells
 
lung epithelial cells
 
Mice intranasally
 
nasopharyngeal colonization
 
pharyngeal epithelial cells
 
pneumococcal nasal colonization
 
Pneumococcal surface protein C
 
sIgA-mediated pneumococcal adherence
 
SK-MES-1 6-fold
 
Streptococcus pneumoniae D39