The expression of β-Defensin-2, IL-22, IL-22R1 and IL-10R2 in rat model of Klebsiella pneumonia and their correlation with histological grades

Backgrounds and Aims:Klebsiella pneumoniae represents the most common opportunistic pathogen contributing to Klebsiella pneumonia in hospital-acquired infections. Klebsiella pneumonia has a rapidly progressive clinical course and multi-drug resistant (MDR). Identification of the effective biochemical markers is crucial for improving early diagnosis and treatment of Klebsiella pneumonia. The aims of our study are to 1) investigate the expression of β-Defensin-2(rβD2), IL-22, IL-22R1 and IL-10R2 in Klebsiella pneumonia-infected rats and 2) their association with the histological grades of Klebsiella pneumonia.Methods and Materials: Fifty specific pathogen free (SPF) male SD rats were randomly divided into two groups: control group (treated with normal saline) and pneumonia group (treated with K. pneumoniae). All Animals were sacrificed 1 h, 12 h, 1 d, 3 d, 5 d post Infection. The severity and property of pneumonia was evaluated by histopathologic observation and pathogen identification. The mRNA expression of rβD2, IL-22, IL-22R1 and IL-10R2 was measured by RT-qPCR assay. The expression of rβD2 in rat lung tissue was determined by Western blot analysis, and the level of IL-22 in rat serum was determined by ELISA.Results: Histopathologic examination and Bacterial counting of lung tissues confirmed the successful establishment of rat pneumonia model. The gene expression of rβD2, IL-22, IL-22R1 and IL-10R2 in pneumonia rats were significantly higher than those in healthy control mice (P < 0.05). The expression of rβD2 was correlated with histological grades of Klebsiella pneumonia and the level of IL-22. RT-qPCR results showed that the peak expression of IL-22R1 appeared earlier than IL-10R2 in rat pneumonia model.Conclusions: The expression of rβD2 and IL-22 was increased significantly at early stage in rat Klebsiella pneumonia model, suggesting that IL-22 and rβD2 might serve as potential biomarkers for the early diagnosis of Klebsiella pneumonia.