The Expression of GATA-3 and FoxP3 Genes and the Frequency of Tregs Are Correlated with Gvhd Following Allogeneic HSCT

Hematopoietic stem cell transplantation (HSCT) is a common therapeutic option for leukemia, but its use is limited by mortality due to graft-versus-host-disease (GVHD). Naturally occurring regulatory T cells (Tregs) are mediators of immunologic tolerance that attenuate GVHD in experimental models. Tregs were first defined by a CD4+CD25+ phenotype, but subsequent studies identified forkhead box protein 3 (FoxP3) as a highly specific marker in both mouse and human T cells with regulatory function. GATA-3 is a member of the GATA family of transcription factors, and is sufficient to induce a Th2 phenotype. GATA-3 could act as an inhibitor of FoxP3 expression in early T cell differentiation was found in transgenic mice model recently. But whether GATA-3 expression could correlate with GVHD incidence, or whether GATA-3 could influence Tregs recovery and contribute to the development of GVHD are still not clear. So we investigated the frequency of Tregs in the early period after HSCT and at the time of GVHD onset, and quantitatively measured the expression of GATA-3 and FoxP3 at GVHD onset for analyzing the correlation to the development of GVHD.

Sixty-seven leukemia patients underwent allogenic (allo-) HSCT were enrolled in this investigation, including 45 males and 22 females (median age: 32.3 years, range 21≂f45). Fourteen healthy individuals (7 males and 7 females, median age: 30.3 years, range 26≂f40) served as controls. Frequencies of T lymphocyte subsets were determined by flow cytometry. The expression levels of human FoxP3 and GATA-3 genes were determined by real-time quantitative PCR with SYBR Green I technique.

The frequencies of CD4+ CD25+ T cells were lower at week 4 post-HSCT, but significant higher after week 4 and lower again after week 8 (P=0.000). The frequencies of FoxP3+ T cells were also lower at week 4 and remained low levels within 12 weeks after HSCT. As early as 4 to 8 weeks after HSCT, the frequencies of CD4+ FoxP3+ T cells were lower than that of week 4 (P=0.048), but the frequencies of CD25+ FoxP3+ T cells were higher than that of week 4 (P=0.022).

Frequencies of CD4+ CD25+ cells in patients at GVHD onset were similar in patients without GVHD (P=0.262) or healthy individuals (P=0.166). But the frequencies of FoxP3+ cells, FoxP3+ CD25+ cells and FoxP3+ CD4+ cells in patients at GVHD onset were significantly lower than that in patients without GVHD (P=0.000, 0.004, and 0.001). The FoxP3 gene expression levels in patients at GVHD onset were significantly lower than that in patients without GVHD (P=0.044), but the GATA-3 gene expression levels were significantly higher in patients at GVHD onset compared to patients without GVHD (P=0.005). The FoxP3 gene expression levels in patients at aGVHD onset were significantly higher than that in patients at cGVHD onset (P=0.038), but the GATA-3 gene expression levels were significantly lower in patients at aGVHD onset compared to patients at cGVHD onset (P=0.004).

A highly significant correlation between FoxP3 and GATA-3 genes expression levels existed in healthy individuals (Spearman correlation coefficient r=-0.893, P=0.007). Correlations between FoxP3 and GATA-3 genes expression levels were also significant in patients at aGVHD onset (Pearson correlation coefficient r=0.749, P=0.020) or cGVHD onset (Pearson correlation coefficient r=0.538, P=0.071) or in GVHD (Spearman correlation coefficient r=0.370, P=0.090). But there is no significant correlation between FoxP3 and GATA-3 genes expression levels in patients without GVHD (Pearson correlation coefficient r=-0.141, P=0.821).

GATA-3 and FoxP3 genes expression and the frequency of Tregs are correlated with GVHD following allogeneic HSCT. GATA-3 can influence the expression of FoxP3 in the development of GVHD.

Supported by National Natural Science Foundation of China(30971300), Science and Technology Planning Project of Guangdong Province of China (2009A030200007) and China Postdoctoral Science Foundation (200902332, 20080440776).

No relevant conflicts of interest to declare.