Modulation of JAK/STAT signaling pathway in the ovine thymus and lymph node during early pregnancy

There is a dynamic accommodation between the maternal immune system and conceptus, including the thymus and lymph nodes, during early pregnancy. Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway is involved in early placentation. However, it was not fully understood that early pregnancy had effects on JAK/STAT signaling pathway in the thymus and lymph nodes of ewes. In this study, thymuses and lymph nodes of ewes were collected at day 16 of the estrous cycle (N16), and at days 13, 16, and 25 of gestation (G13, G16, and G25). Expressions of mRNA and protein of JAK/STAT members, including interferon α/β receptor 1 (IFNAR1), JAK1, tyrosine kinase 2 (TYK2), STAT3, interferon regulatory factor 9 (IRF9), B-cell lymphoma-extra large (BCL-XL), BCL-2, myelocytomatosis viral oncogene homolog (c-Myc), and p21 (a protein with a molecular weight of 21 kDa), were analyzed. The results indicated that there were increases in mRNA and protein expression of p-IFNAR1, p-JAK1, TYK2, p-STAT3, IRF9, and p21 in the thymus, and p-STAT3 and BCL-XL in lymph nodes. In addition, expression levels of p-IFNAR1 and p-JAK1 in the thymus and c-Myc in lymph nodes peaked at G16, but expression levels of c-Myc, BCL-XL, BCL-2, and P21 peaked at G13 in the thymus. Furthermore, expression levels of TYK2 and p-STAT3 in the thymus and p-JAK1, TYK2, and P21 in lymph nodes were higher at G16 and G25. P21 and p-IFNAR1 peaked at G25, but IRF9 peaked at N16. BCL-2 level was greater at N16 and G25. In summary, early pregnancy modulated JAK/STAT signaling pathway in the maternal thymus and lymph nodes in a pregnancy-stage- and tissue-specific manner, which may be associated with the establishment of maternal immune tolerance during early pregnancy in ewes.