Effect of icariin on early β-defensin-2 and T cell subsets in rats after tracheotomy

To investigate the effect of icariin (ICA) on early β-defensin-2 and T cell subsets in rats after tracheotomy.

A total of 54 SPF male Sprague-Dawley rats were randomly divided into a normal control group (group A), a model group (group B), and a model+ICA treatment group (group C), with 18 rats in each group. A tracheotomy intubation model of the B and C group was prepared. After 6 h of surgery, ICA intervention was given to group C. Groups A and B were given the same amount of normal saline. Lung tissue, alveolar lavage fluid and peripheral blood were taken at 24 h, 72 h and 168 h, respectively. The expression of rat β-defensin-2 mRNA in lung tissue was detected by RT-PCR. The content of β-defensin-2 in alveolar lavage fluid and peripheral blood serum was detected by ELISA. The content of peripheral blood T cell subsets (CD3⁺, CD4⁺, CD8⁺) was detected by flow cytometry, and the ratio of CD4⁺/CD8⁺ was calculated.

After tracheotomy, the levels of β-defensin-2 mRNA and β-defensin-2 in lung tissue from the group B were increased significantly at 24 h, then they were decreased gradually, and decreased most significantly at 168 h (P<0.05). The content of β-defensin-2 in peripheral blood of group B decreased gradually, and the content of β-defensin-2 in 168 h was significantly lower than that in 24 h (P<0.05), but there was no significant difference between group B and group A (P>0.05). The level of CD3⁺ T cells in peripheral blood was significantly lower than that in the group A (P<0.05), but their was no significant difference in CD4⁺ and CD8⁺ T cells compared with group A (P>0.05). After ICA intervention in group C: lung tissue, alveolar lavage fluid, peripheral blood serum β-defensin-2 content, and peripheral blood CD3⁺ and CD4⁺ T cell levels were gradually increased, significantly higher than those in the group B (P<0.05). CD8⁺ T cell level was significantly lower than that in the group A at 24 h (P<0.05), the CD4⁺/CD8⁺ ratio was significantly higher at 168 h than those in the group A or B (both P<0.01).

ICA can improve the early lung immune function in rats with tracheotomy, which might be related to up-regulation of β-defensin-2 in lung tissue and alveolar lavage fluid, concomitant with increases in CD3⁺ and CD4⁺ T cells and CD4⁺/CD8⁺ ratio in peripheral blood while reduction in CD8⁺ cells.