Effect of Neuraminidase on Receptor-mediated Adherence of Streptococcus pneumoniae to Chinchilla Tracheal Epithelium

Abstract

The trachea whole organ perfusion technique was used to study the effect of the disruption of the Streptococcus pneumoniae neuraminidase nanA gene on bacterial adherence and alteration of the carbohydrate surface structures of respiratory epithelial cells. Six different lectin probes were used to examine alterations of the cell surface carbohydrates in chinchilla tracheal epithelium incubated in vitro with S. pneumoniae deltaNA1, a neuraminidase-deficient mutant, or its D39 parent strain. The labeling pattern revealed that the binding of wheat germ agglutinin (WGA), Erythrina cristagalli lectin (ECL), peanut agglutinin (PNA), Bandeiraea simplicifolia lectin II (BSL II) and succinylated WGA was significantly increased in the luminal surface of the trachea in the D39-incubated cohort compared with the uninfected control, which indicated that GlcNAc and D-galactose residues were exposed. Concurrently, decreased labeling with Sambucus nigra agglutinin (SNA) indicated that there were few sialic acid residues remaining in the tracheal epithelium subsequent to incubation with D39. The deltaNA1 neuraminidase-deficient mutant, however, did not induce any significant changes in the lectin labeling patterns, which were comparable to those of the control cohort. Moreover, adherence data expressed as colony-forming units (CFU) of S. pneumoniae per millimeter of trachea indicated a significant decline in the ability of deltaNA1 to adhere in vitro. We propose that products of the nanA gene have a significant impact on changes in the carbohydrate moieties in the tracheal epithelium, and may be responsible for the previously reported increased ability of the D39 parent to colonize the nasopharynx and invade the middle ear.

Versatility of pneumococcal surface proteins

“…NanA and NanB are secreted via the general secretory pathway, but only the Cterminus of NanA contains the LPxTG anchoring motif. Loss of NanA has been shown to impair pneumococcal persistence in the nasopharynx and middle ear in a chinchilla infection model (Tong et al, 2002). In contrast, the nanA knockout is not attenuated in an intraperitoneal infection model (Berry & Paton, 2000).…”

Influenza Virus Infection Decreases Tracheal Mucociliary Velocity and Clearance ofStreptococcus pneumoniae

“…In particular, S. pneumoniae adherence has been studied using chinchilla tracheal explants (30,38). A distinct advantage of a tracheal explant system is that the differentiated tissue more accurately reproduces influenza and respiratory epithelial cell interactions with pneumococci than do in vitro-grown cellular monolayer assays of adherence.…”

“…the interactions of several bacterial and viral pathogens, such as Mycoplasma spp., Bordetella spp., influenza virus, cytomegalovirus, and S. pneumoniae, with the respiratory epithelium have been studied (30,31,(34)(35)(36)(37)(38). In particular, S. pneumoniae adherence has been studied using chinchilla tracheal explants (30,38).…”

“…Tracheal explant systems, such as tracheal rings or wholeorgan explants, from a variety of animal species, including hamsters, mice, rats, ferrets, pigs, guinea pigs, and chinchillas, have been widely used as an alternative to in vitro cell culture assays (30)(31)(32)(33)(34)(35)(36)(37)(38)(39). Tracheal explants have been used to investigate the effects of toxins, such as mineral dusts, air pollution particles, and cigarette smoke, on tracheal function (32,33,39).…”

Inducing host protection in pneumococcal sepsis by preactivation of the Ashwell-Morell receptor

“…For example, NanA remodels mucosal cell surface glycoproteins to promote bacterial colonization of the upper respiratory tract (11,12) and contributes to pulmonary inflammation along with the development of SPN pneumonia (13,14). However, the host has adapted to counteract the pathological effects of this SPN virulence factor by the clearance from blood circulation of host factors bearing AMR ligands that have been unmasked by NanA desialylation.…”