Modulation of NF-κB and TLR Signaling Pathways and Complement Components in Ovine Maternal Thyroid During Early Pregnancy

Pregnancy modulates the function of the thyroid gland to facilitate maternal immune tolerance, and nuclear factor kappa B (NF-κB) subunits, the IκB family, and toll-like receptors (TLRs) and complement signaling pathways may be implicated in maternal thyroid immunoregulation. However, it is unclear whether early pregnancy modulates the expression of NF-κB subunits, the IκB family, TLRs, and complement components in the maternal thyroid. The objective of this study was to analyze the effects of early pregnancy on the expression of genes and proteins of these signaling pathways in the maternal thyroid in ewes. In this study, ovine thyroids (n = 6 for each group) were sampled on day 16 of the estrous cycle (N16) and on days 13, 16, and 25 of pregnancy (P13, P16, and P25) with one conceptus. The ewes had an average weight of 41 kg and a body condition score of 3. The mRNA and protein expression of the NF-κB subunits and IκB family were analyzed by RT-qPCR, western blot, and immunohistochemistry. The results showed that the expression of all NF-κB subunits, the IκB family, and TLRs, as well as C1q, C1r, C2, C4a, C5b, and C9, peaked at P16 among these four stages (p < 0.05). In addition, C1s expression was greater at N16 and P16 than at P13 and P25 (p < 0.05), and C3 expression was stronger at P16 and P25 compared to N16 and P13 (p < 0.05). In conclusion, early pregnancy modulates the expression of NF-κB subunits, the IκB family, TLRs, and complement components in the ovine thyroid at both the mRNA and protein levels, which may be essential for maternal thyroid adaptation to pregnancy and beneficial for the prevention of pregnancy-related thyroid diseases in ewes.