Expression of the Th1-Specific Cell-Surface Protein Tim-3 Increases in a Murine Model of Atopic Asthma

Abstract

T-cell immunoglobulin- and mucin-domain-containing molecule-3 (Tim-3) is preferentially expressed on Th1-helper type T-cells and functions to repress the Th1-mediated immune response. However, the role of Tim-3 during the inflammatory pathogenesis of asthma remains unclear. This study determines the expression level of Tim-3 in CD4⁺ T-cells within the peripheral blood and bronchoalveolar lavage fluid (BALF) isolated from a murine model of atopic asthma and explores the potential role of Tim-3 during the inflammatory response. Mice were randomly divided into normal control, asthma day 1, and asthma day 7 groups, and peripheral blood T lymphocytes and BALF cells were collected. The ratio of Tim-3⁺/CD4⁺ cells among the total CD4⁺cell populations from peripheral blood and BALF was determined by flow cytometry, and the expression of the Tim-3 mRNA was determined by Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR). In contrast with the normal control group, the ratio of Tim-3⁺/CD4⁺:CD4⁺ cells and the level of Tim-3 mRNA in both the peripheral blood T lymphocytes and BALF cells among the asthma day 1 and asthma day 7 groups were significantly increased (p < 0.01), and those in the asthma day 7 group were higher than the asthma day 1 group (p < 0.05). There was also a positive correlation between the ratio of Tim-3⁺/CD4⁺:CD4⁺ detected in BALF and that the ratio detected in peripheral blood T lymphocytes (r = 0.84, p < 0.01). Therefore, the expression of Tim-3 is increased in CD4+ T-cells following airway challenge and likely affects asthma-induced inflammation by repressing the Th1-mediated immune response.

Keywords :

• asthma
• inflammation
• T lymphocyte
• Th1/Th2 cells
• Tim-3

Acknowledgment

This work was supported by the National Natural Science Foundation of China (grant 30801260), the New Teacher Foundation of the Ministry of Education of P. R. China (grant 200804871068), and partly supported by the National Natural Science Foundation of China (grant 30770946).