TY - JOUR
T1 - Pseudomonas aeruginosa alginate is refractory to Th1 immune response and impedes host immune clearance in a mouse model of acute lung infection.
AU - Song, Zhijun
AU - Wu, Hong
AU - Ciofu, Oana
AU - Kong, Kok-Fai
AU - Høiby, Niels
AU - Rygaard, Jørgen
AU - Kharazmi, Arsalan
AU - Mathee, Kalai
N1 - Keywords: Acute Disease; Alginates; Animals; Colony Count, Microbial; Cystic Fibrosis; Cytokines; Disease Models, Animal; Female; Humans; Interleukin-4; Lung; Lung Diseases; Mice; Mice, Inbred Strains; Pseudomonas Infections; Pseudomonas aeruginosa; Spleen; Th1 Cells; Up-Regulation; Virulence
PY - 2003
Y1 - 2003
N2 - Pseudomonas aeruginosa is an opportunistic respiratory pathogen that accounts for most of the morbidity and mortality in cystic fibrosis (CF) patients. In CF-affected lungs, the bacteria undergo conversion from a non-mucoid to a non-tractable mucoid phenotype, due to overproduction of alginate. The effect of alginate production on pathogenicity was investigated by using an acute lung infection mouse model that compared a non-mucoid P. aeruginosa strain, PAO1, to its constitutive alginate-overproducing derivative, Alg(+) PAOmucA22, and an alginate-defective strain, Alg(-) PAOalgD. Bacterial suspensions were instilled into the left bronchus and examined 24 and 48 h post-infection. The highest bacterial loads and the most severe lung pathology were observed with strain Alg(-) PAOalgD at 24 h post-infection, which may have been due to an increase in expression of bacterial elastase by the mutant. Significantly lower lung and spleen bacterial loads were found in the two non-mucoid (PAO1 and Alg(-) PAOalgD) groups, compared to the mucoid Alg(+) PAOmucA22 group, between 24 and 48 h post-infection. The positive correlation between lung bacteriology and lung macroscopic pathology in the Alg(+) PAOmucA22 group suggests that alginate production not only impedes pulmonary clearing, but also results in severe lung damage. Positive correlations between IL12 levels and lung macroscopic pathology, and between IL12 and IFN-gamma levels in the Alg(+) PAOmucA22 group, suggested a possible contribution of these pro-inflammatory cytokines to tissue damage. No significant differences were found between the three groups in lung cytokine responses at 24 or 48 h post-infection. However, on comparison within each group at 24 and 48 h post-infection, a significant increase in the pro-inflammatory cytokine IFN-gamma was observed. Higher ratios of IFN-gamma/IL4 and IFN-gamma/IL10, but lower IL10 levels, were also found in all three groups. These results indicate a Th1-predominated immune response in these animals. Such cytokine responses could have aided the clearance of non-mucoid P. aeruginosa, but were not sufficient to alleviate infection by the mucoid variants. Alginate production may promote survival and persistence of this pathogenic micro-organism in the lung.
AB - Pseudomonas aeruginosa is an opportunistic respiratory pathogen that accounts for most of the morbidity and mortality in cystic fibrosis (CF) patients. In CF-affected lungs, the bacteria undergo conversion from a non-mucoid to a non-tractable mucoid phenotype, due to overproduction of alginate. The effect of alginate production on pathogenicity was investigated by using an acute lung infection mouse model that compared a non-mucoid P. aeruginosa strain, PAO1, to its constitutive alginate-overproducing derivative, Alg(+) PAOmucA22, and an alginate-defective strain, Alg(-) PAOalgD. Bacterial suspensions were instilled into the left bronchus and examined 24 and 48 h post-infection. The highest bacterial loads and the most severe lung pathology were observed with strain Alg(-) PAOalgD at 24 h post-infection, which may have been due to an increase in expression of bacterial elastase by the mutant. Significantly lower lung and spleen bacterial loads were found in the two non-mucoid (PAO1 and Alg(-) PAOalgD) groups, compared to the mucoid Alg(+) PAOmucA22 group, between 24 and 48 h post-infection. The positive correlation between lung bacteriology and lung macroscopic pathology in the Alg(+) PAOmucA22 group suggests that alginate production not only impedes pulmonary clearing, but also results in severe lung damage. Positive correlations between IL12 levels and lung macroscopic pathology, and between IL12 and IFN-gamma levels in the Alg(+) PAOmucA22 group, suggested a possible contribution of these pro-inflammatory cytokines to tissue damage. No significant differences were found between the three groups in lung cytokine responses at 24 or 48 h post-infection. However, on comparison within each group at 24 and 48 h post-infection, a significant increase in the pro-inflammatory cytokine IFN-gamma was observed. Higher ratios of IFN-gamma/IL4 and IFN-gamma/IL10, but lower IL10 levels, were also found in all three groups. These results indicate a Th1-predominated immune response in these animals. Such cytokine responses could have aided the clearance of non-mucoid P. aeruginosa, but were not sufficient to alleviate infection by the mucoid variants. Alginate production may promote survival and persistence of this pathogenic micro-organism in the lung.
M3 - Journal article
C2 - 12909647
SN - 0022-2615
VL - 52
SP - 731
EP - 740
JO - Journal of Medical Microbiology
JF - Journal of Medical Microbiology
IS - Pt 9
ER -