Abstract
The maternal immune system during pregnancy is largely changed to maintain immune tolerance against the embryo. Although thymus tissues, which generate T cells, are also dynamically altered during pregnancy, the precise phenotype of thymic T cells and gene alteration in thymus tissues remain to be completely elucidated. In this study, we performed a comprehensive analysis of gene expression and assessed T-cell phenotypic changes in the thymus of mice during pregnancy. Thymus tissues of female C57BL/6 mice during pregnancy were resected to investigate T-cell phenotypes using flow cytometric and immunofluorescence analyses and gene expression using a DNA microarray. Decreased weight of thymus tissues was observed during gestation. Cell numbers of total populations of thymic T cells in pregnant mice were significantly decreased compared with those in non-pregnant mice. DNA microarray and RT-PCR analyses revealed several upregulated genes in the thymus tissues of pregnant mice. Among them, the insulin growth factor-binding protein 5 (IGFBP5) was the most upregulated gene, and its increased protein expression of macrophages was confirmed by immunofluorescence analysis. In summary, a unique change in gene expression was observed in transient atrophy of thymus tissues during pregnancy. The change in gene expression, including that in IGFBP5 of macrophages, may influence thymic differentiation of T cells to maintain an immunological tolerance during pregnancy.
