Effects of exposure to cigarette smoke on the counts and functions of tDC and Treg cells in a mouse model of asthma

Abstract

Objective To investigate the effects of exposure to cigarette smoke on the counts and functions of tolerogenic dendritic cells(tDC) and regulatory T cells(Treg) in a mouse model of asthma. Methods Forty female BALB/c mice at age 20 days were randomly allocated into four groups including the normal saline (NS)/air treatment group, the NS/cigarette smoke (CS) treatment group, the ovalbumin (OVA)/air treatment group and the OVA/CS treatment group (n=10). A mouse model of asthma was established by intraperitoneally injecting OVA in an interval of two weeks to cigarette smoke for three weeks. The percentages of Treg cells in PBMCs and the changes of CD80 and CD86 expression on the surface of DCs of the mice in each group were analyzed by flow cytometry analysis. The transcriptional levels of forkhead box P3 (Foxp3) in lung tissues were measured by real-time quantitative PCR. The levels of IFN-γ, IL-4, IL-6, IL-10, IL-12p40, IL-17A and TGF-β1 in bronchoalveolar lavage fluid (BALF) samples were measured by ELISA. Results Exposing young mice to cigarette smoke significantly increased the percentages of Treg cells in PBMCs and the expression of Foxp3 at mRNA level in lung tissues of mice with asthma. High levels of TGF-β1 and IL-10 were detected in BALF samples of the heathy mice and those with asthma exposed to CS at a young age. The mice with asthma exposed to CS at an early age showed decreased expression of CD80 and CD86 on the surface of DCs. Lower levels of IL-12p40 and IL-6 and higher levels of IFN-γ, IL-4 and IL-17A in BALF samples were observed in mice from the OVA/CS treatment group. Conclusion Exposing to cigarette smoke at an early age was involved in the dysfunction of T cell-mediated immune responses in mice with asthma. This study might provide new ideas for the prevention and treatment of asthma. Key words: Cigarette smoke; Regulatory T cell; Tolerogenic dendritic cell