Mucosal clearance of capsule-expressing bacteria requires both TLR and nucleotide-binding oligomerization domain 1 signaling

TA Zola, ES Lysenko, JN Weiser - The Journal of Immunology, 2008 - journals.aai.org
TA Zola, ES Lysenko, JN Weiser
The Journal of Immunology, 2008journals.aai.org
Expression of capsular polysaccharide by bacterial pathogens is associated with increased
resistance to host clearance mechanisms, in particular by evading opsonization and uptake
by professional phagocytes. The potential for rapid progression of disease caused by
encapsulated bacteria points to the importance of innate immunity at the mucosal surface
where infection is initiated. Using a murine model of nasopharyngeal colonization, host
immune components that contribute to the mucosal clearance of capsule-expressing …
Abstract
Expression of capsular polysaccharide by bacterial pathogens is associated with increased resistance to host clearance mechanisms, in particular by evading opsonization and uptake by professional phagocytes. The potential for rapid progression of disease caused by encapsulated bacteria points to the importance of innate immunity at the mucosal surface where infection is initiated. Using a murine model of nasopharyngeal colonization, host immune components that contribute to the mucosal clearance of capsule-expressing bacteria were investigated. Clearance of encapsulated Haemophilus influenzae (Hi) required both TLR and nucleotide-binding oligomerization domain (NOD) signaling pathways, whereas individual deficiencies in each of these signaling cascades did not affect clearance of nonencapsulated strains. Moreover, clearance of Hi-expressing capsular polysaccharide required the recruitment of neutrophils to the site of infection, and ex vivo phagocytic bacterial killing required expression of the NOD1 signaling pathway. Conversely, redundancies within these innate immune pathways of non-neutrophil cells were sufficient to promote mucosal clearance of nonencapsulated Hi. Our findings reveal a role for NOD1 in protection from encapsulated pathogens. In addition, this study provides an example of a microbial virulence determinant that alters the requirements for host signaling to provide effective protection.
journals.aai.org