Expressions of sST2/IL-33 and Th17/Treg-related cytokines in rats with Pseudomonas aeruginosa-induced pneumonia

OBJECTIVE To explore the expression levels of soluble growth stimulating gene 2 (sST2)/interleukin-33 (IL-33) and helper T cell 17 (Th17)/regulatory T cell (Treg)-related cytokines in rats with pneumonia induced by Pseudomonas aeruginosa and observe the significance. METHODS Totally 60 SD rats were randomly divided into the blank control group, the 12-h pneumonia group, the 1-d pneumonia group, the 3-d pneumonia group, the 5-d pneumonia group and the 7-d pneumonia group, with 10 rats in each group. All of the rats were nasally dripped with P.aeruginosa to establish the rat models with pneumonia except for the rats in the blank control group. The lung function indexes of the rats were detected, the peripheral blood Th17 and Treg were detected by flow cytometry, the bronchoalveolar lavage fluid (BALF) specimens were collected from the rats so as to carry out the bacterial culture, the bacterial colony counts, white blood cell counts and neutrophil counts were recorded; the levels of sST2, IL-33, IL-17, IL-23, tumor necrosis factor -α(TNF-α) and IL-1β in BALF were detected by enzyme-linked immunosorbent assay, and the association between them was observed. RESULTS As compared with the blank control group, the bacterial colony counts, white blood cell counts, neutrophil counts in BALF and sST2, IL-33, IL-17, IL-23, TNF-α and IL-1β in BALF as well as peripheral blood Th17 and Th17/Treg were firstly elevated and then declined (P<0.05), while the peripheral blood Treg level firstly declined and then rose(P<0.05), reaching the lowest level on Day 5(P<0.05); the forced vital capacity(FVC)and forced expiratory volume in 0.3 second (FEV0.3)reduced(P<0.05). Pearson correlation analysis showed that the BALF sST2 and IL-33 were positively correlated with Th17/Treg, IL-17, IL-23, TNF-α and IL-1β, respectively(P<0.05). CONCLUSION The peripheral blood sST2/IL-33 may participate in the process of induction of pneumonia by P.aeruginosa by regulating the immune balance of Th17/Treg and related cytokines and play a significant role in acute attack of disease.