Comparison of Th1 and Th2 cytokines production in ovine lymph nodes during early pregnancy

Abstract

As a fetal allograft to the mother, early conceptus regulates the intrauterine immune and systemic immune responses during early pregnancy in sheep. However, expression of T helper 1 (Th1) and Th2 cytokines in maternal lymph nodes is unclear during early pregnancy in sheep. In this study, inguinal lymph nodes were obtained on day 16 of the estrous cycle and on days 13, 16 and 25 of pregnancy (n = 4 for each group) in ewes, and qRT-PCR, western blot and immunohistochemistry were used to compare the expression of Th1 and Th2 cytokines in the lymph nodes. Our results showed that there were the highest levels of Th1 cytokines (IFN-γ, TNF-β and IL-2) and Th2 cytokines (IL-4, IL-5, IL-6 and IL-10) in the lymph nodes on day 13 or 16 of pregnancy. Furthermore, there were a downregulation of TNF-β and IL-2 and an upregulation of IL-5 and IL-10 on day 25 of pregnancy compared with that in nonpregnancy, with no significant difference in the expression of IFN-γ, IL-4, and IL-6 between the ewes on day 25 of pregnancy and nonpregnancy. The immunohistochemistry results showed that the IL-2 and IL-10 proteins were limited to the subcapsular sinus and trabeculae in the cortex, lymph sinus. In conclusion, early pregnancy exerted its effects on the lymph node and induced a Th2-biased response, which was essential for a normal pregnancy in sheep.

Keywords: Lymph node; Pregnancy; Sheep; T helper cytokine.