Impaired upregulation of keratinocyte growth factor in injured lungs induced by Pseudomonas aeruginosa in immunosuppressed rats.
BACKGROUND
The number of immunosuppressed patients has increased in the past decades. Among them Pseudomonas aeruginosa (P. aeruginosa) is one of the leading bacteria for pneumonia that are associated with poor prognosis. However, the pathogenesis of P. aeruginosa pneumonia in immunosuppressed patients is not understood completely. Previous reports showed keratinocyte growth factor (KGF) is associated with lung injury in immunocompetent hosts. In this study, we investigated the different reactions of lung injury, lung pathology and KGF expressions in P. aeruginosa pneumonia between immunosuppressed and immunocompetent rats.


METHODS
Immunosuppression of male rats was induced by injecting immunosuppressive subcutaneously. Pneumonia was established by instilling P. aeruginous tracheally. The immunocompetent rats were the control group. Survival rate, lung histopathology, pulmonary permeability and oedema, KGF mRNA and protein expressions in lungs of both groups were investigated.


RESULTS
The survival rate of immunosuppressed group was lower than that of immunocompetent group (33.3% vs 83.3%). After exposure to bacteria, pulmonary permeability and wet/dry ratio in immunosuppressed group were higher than those in immunocompetent group. Pulmonary congestion and haemorrhage were more intensive in immunosuppressed group compared to immunocompetent group. Apoptosis and necrosis were also observed in infected lungs of immunosuppressed rats. Although we detected KGF expressions in lungs of both groups after infection, the expressions of KGF protein and mRNA gene in immunosuppressed group were much lower than in immunocompetent group.


CONCLUSIONS
Compared with immunocompetent group, there was more intensive lung injury in immunosuppressed group. Severe lung injury may contribute to the poor prognosis of pneumonia. KGF expressions of pneumonia in immunosuppressed rats were less than those in immunocompetent ones.
Xu
Jin-fu
JF
Department of Pulmonary Medicine, Zhongshan Hospital, Fudan University, Shanghai 200032, China.
Qu
Jie-ming
JM
He
Li-xian
LX
Ou
Zhou-luo
ZL
D000818:Animals; D002199:Capillary Permeability; D051523:Fibroblast Growth Factor 7 / Q000032:analysis / Q000235:genetics*; D007108:Immune Tolerance; D007958:Leukocyte Count; D008168:Lung / Q000378:metabolism* / Q000473:pathology; D008297:Male; D018410:Pneumonia, Bacterial / Q000378:metabolism*; D011552:Pseudomonas Infections / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D011654:Pulmonary Edema / Q000209:etiology; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D015996:Survival Rate; D015854:Up-Regulation
D012333:RNA, Messenger; D051523:Fibroblast Growth Factor 7