To determine whether rSj16 could induce regulatory T cells in vitro, spleen mononuclear cells were isolated from the naïve mice and cultured in the presence of rSj16, SEA or OVA, respectively. Four days later, cells were analysed by flow cytometry (FCM) for the expression of CD4, CD25 and Foxp3, a regulatory function-related marker that is known to be expressed in regulatory T cells and not in activated T cells (24). The results showed that the proportion of CD4+CD25+Foxp3+ T cells in rSj16-treated groups significantly increased compared with SEA, OVA or medium-treated groups (Figure 1a). We then examined whether CD4+CD25+Foxp3+ T cells could be induced by rSj16 in vivo. CD4+ T cells were isolated from the
spleens of mice injected with rSj16, SEA, OVA, incomplete Freund’s adjuvant (IFA) or PBS, respectively. selleck chemicals The number of CD4+CD25+Foxp3+ T cells was detected by FCM. The proportion of CD4+CD25+Foxp3+ T cells in rSj16-injected group significantly increased compared to SEA, OVA or PBS-injected groups (Figure 1b). Taken together, these results indicated that rSj16 treatment increased CD4+CD25+Foxp3+ T-cell populations both in vivo and in vitro. To further test whether CD4+CD25− T cells can be differentiated into CD4+CD25+Foxp3+ T cells by rSj16; CD4+CD25− T cells were purified and stimulated in vitro with rSj16 in presence of APCs. The number of CD4+CD25+Foxp3+ T cells was also detected by FCM. The results
showed that the proportion of CD4+CD25+Foxp3+ T cells in rSj16-treated groups significantly increased compared with SEA, OVA or medium-treated groups (Figure 1c). The results suggested that the increase of CD4+CD25+Foxp3+ T cells was Selumetinib supplier from the conversion of CD4+CD25− T cells. To determine whether the suppressive activity of CD4+CD25+ T cells could be enhanced by rSj16 in vitro,
CD4+CD25+ T cells from naïve mice were pretreated in vitro with rSj16, OVA or PBS, respectively, then cocultured with responder naïve murine CD4+CD25− T cells in presence of anti-CD3 and APCs (25,26). It is showed that all OVA-, PBS- and rSj16-pretreated Tregs were able to inhibit proliferation of CD4+CD25− T cells, but the degree of inhibition was enhanced in rSj16-treated cells compared with PBS- or OVA-pretreated cells (Figure 2a). We then tested whether Tregs generated by injection with rSj16 could exhibit inhibitory activity in vivo. CD4+CD25+ T cells purified from Sodium butyrate rSj16-, SEA-, OVA- or PBS-injected mice were cocultured with responder cells, and the degree of suppression was assessed as described above. The results showed that CD4+CD25+ T cells from SEA-, OVA- or PBS-injected mice were effective in suppressing CD4+CD25− T-cell proliferation, but the degree of inhibition was even higher for CD4+CD25+ T cells purified from rSj16-injected mice (Figure 2b). To study the types of suppression of rSj16-induced regulatory T cells, we measured the concentration of the cytokines in supernatants of naïve mouse splenocytes cocultured with different antigens.