BACKGROUND:Mesenchymal stem cel s have an immunoregulatory capacity to suppress the airway inflammation of asthmatic mice, but the mechanism remains unclear. Our preliminary studies indicated that mesenchymal stem cel s can upregulate the CD4+CD25+regulatory T cel s (Treg) of the asthmatic mice. OBJECTIVE:To study the effect of mesenchymal stem cel s on the airway inflammation in asthmatic BALB/c mice depleted of CD4+CD25+Treg. METHODS:Forty BALB/c mice were randomly divided into five groups:normal control group (group A), asthmatic group (group B), asthmatic group depleted of CD4+CD25+Treg (group C), mesenchymal stem cel s group (group D), and asthmatic group depleted of CD4+CD25+Treg and administrated with mesenchymal stem cel s (group E). Except group A, mice in the other groups were sensitized and chal enged by ovalbumin to establish asthma models. In group C and group E, each mouse was treated with anti-CD25+monoclonal antibody to deplete CD4+CD25+Treg. In group D and group E, mice were intravenously administered with 0.2 mL mesenchymal stem cel s 1×109/L) at 10 days after sensitization. At 24 hours after the final activation, the number of CD4+CD25+Treg in the peripheral blood was detected by flow cytometry. The total cel number of inflammatory cel s in the bronchoalveolar lavage fluid, and the number of eosinophils, lymphocytes and neutrophils were counted to analyze the degree of inflammation of the airway together with pathological observation. RESULTS AND CONCLUSION:(1) The proportion of CD4+CD25+Treg in peripheral lymphocytes was ranged as fol ows:group B

BACKGROUND:The surface antigen CD80/CD86 on mature dendritic cells can activate helper T (Th) cells, reduce the differentiation of Th cells toward Th1 cells, and promote the differentiation of Th cells toward Th2 cells.
OBJECTIVE:To investigate the effect of smal interfering RNA (siRNA) inhibiting the expression of surface antigens CD80/CD86 from asthmatic murine mature dendritic cells on Th1/Th2 type cytokines, interferon-γand interleukin-4.
METHODS:Asthmatic model of mice was established;then bone marrow-derived mature dendritic cells were separated and cultured. The expression of CD11c, CD80 and CD86 on mature dendritic cells were examined by flow cytometry. The siRNA was transferred into mature dendritic cells of asthmatic mice, and the CD80/CD86 mRNA and protein expression before and after interference were determined by fluorescent quantitative PCR and flow cytometry. The mature dendritic cells in non-siRNA group, siRNA group and negative siRNA group were co-cultured with T cells. The interferon-γand interleukin-4 productions were measured by enzyme-linked immunosorbent assay.
RESULTS AND CONCLUSION:(1) The expression of CD80/CD86 on the mature dendritic cells of asthmatic group was significantly higher than that in normal control group (al P<0.05). (2) After siRNA was transferred into mature dendritic cells, the expression level of CD80/CD86 mRNA and protein in siRNA group was significantly lower than other groups (al P<0.05). (3) After siRNA transfection, the level of interferon-γfrom the supernatant of mature dendritic cells and T cells co-culture system was significantly increased in the siRNA group compared with other groups (al P<0.05), while interleukin-4 production in the siRNA group was significantly decreased (al P<0.05). These findings suggest that high expression of CD80/CD86 on mature dendritic cells of asthmatic mice is observed, specific siRNA can effectively inhibit the expression of CD80/CD86, thus increasing interferon-γproduction and decreasing interleukin-4 production, which contributes to regulate the Th1/Th2 imbalance.