The role of the lactadherin in promoting intestinal DCs development in vivo and vitro

Abstract

Lactadherin, as one of the immune components in the breast milk, might play a role in the intestinal immune system of newborn. Therefore, we investigated the effect of lactadherin-feeding in early time on the development of intestinal immune system compared with naturally rearing and artificially rearing (non-lactadherin). In the present study, we observed that the Peyer's Patches (PP) from the pups of artificially reared group with lactadherin added were characterized by an excess of OX62(+)CD4(+)SIRP(+) DC cells and a higher expression of CD3(+)CD4(+)CD25(+)T cells. Additionally, this study also demonstrated that IL-10 production was dramatically increased when lactadherin was present in culture medium compared with lactadherin-absent culture. These results suggested that lactadherin could adjust intestinal DCs activity, induce CD3(+)CD4(+)CD25(+)T cell differentiation, and enhance IL-10 production.

Figure 1

The expression of OX62⁺DCs and OX62⁺CD4⁺SIRP⁺DCs of each groups at various development stages (Mean ± SD). (a) The expression level of OX62⁺DCs of each group at different stages. (b) The expression level of OX62⁺CD4⁺SIRP⁺ DCs of each group at different stages. (c) Single-cell suspensions of the total PP-DCs in rats were identified by OX62. The difference of OX62⁺DC among groups at different development stages was not significant. (F = 3.0, 0.587, 3.267, and 1.471, resp.; P > .05). Significant growth occurred in LR group for the number of OX62⁺CD4⁺SIRP⁺DCs at age week 3. Levels of OX62⁺CD4⁺SIRP⁺DC subsets at every age were highly significant in LR group and BR group compared with AR group. Furthermore, the positive cell numbers were higher in LR group than in BR group. The positive cell numbers kept stable in LR group at various ages while the positive cells number increased with age in the other two groups. Significant numbers of OX62⁺CD4⁺SIRP⁺DCs were found in LR and BR group at various ages (Figures 1(b) and 1(c)) compared with AR group (A: BR at W3, B: AR at W3, C: LR at W3, D: BR at W5, E: AR at W5, F: LR at W5, G: BR at W7, H: AR at W7, I: LR at W7, J: BR at W11, K: AR at W11, L: LR at W11). *P < .05.

Figure 2

Flow cytometric analyses of CD3⁺CD4⁺CD25⁺T-cells in PPs of each group in different development stages (Mean ± SD). In order to investigate T cells proliferation and differentiation in three differently fed groups, we examined the phenotype of CD3⁺CD4⁺T cells subpopulation in the PPs by assessing the relative proportions of CD3⁺CD4⁺CD25⁺T cells. The results showed that the group of LR rats had a higher relative proportion of CD3⁺CD4⁺CD25⁺  T cells in PPs (b A: BR at W3, B: AR at W3, C: LR at W3, D: BR at W5, E: AR at W5, F: LR at W5, G: BR at W7, H: AR at W7, I: LR at W7, J: BR at W11, K:AR at W11, L: LR at W11). *P < .05.

Figure 3

Levels of IL-12 and IL-10 production in lactadherin-present and -absent DC cultures (Means±SD). No significant differences in IL-12 production were observed with or without lactadherin present in the culture medium. However, IL-10 production was dramatically increased when lactadherin was present in the culture medium compared to when it was absent.