Expression of nuclear factor kappa B in ovine maternal inguinal lymph nodes during early pregnancy

BACKGROUND: Pregnancy-induced immunological changes contribute to the maternal immune tolerance. Nuclear factor kappa B (NF-κB) pathway participates in regulating both innate and adaptive immunities, and lymph nodes play key roles in adaptive immune reaction. However, it is unclear whether early pregnancy changes the expression of NF-κB family in maternal lymph node in sheep. METHODS: In this study, the samples of inguinal lymph nodes were collected from ewes on day 16 of the estrous cycle, and on days 13, 16 and 25 of pregnancy, and expression of NF-κB family, including NF-κB p105 (NFKB1), NF-κB p100 (NFKB2), p65 (RELA), RelB (RELB) and c-Rel (REL), were analyzed through real-time quantitative PCR, Western blot and immunohistochemical analysis. RESULTS: The expression levels of NF-κB p105 and c-Rel downregulated, but NF-κB p100 upregulated on day 25 of pregnancy. The expression levels of p65, RelB and c-Rel peaked at day 13 of pregnancy, and expression level of RelB was higher during early pregnancy comparing to day 16 of the estrous cycle. In addition, p65 protein was located in the subcapsular sinus and lymph sinuses. CONCLUSION: This paper reported for the first time that early pregnancy has effects on the expression of NF-κB family, which may contribute to the maternal immunoregulation through blood circulation and lymph circulation during early pregnancy in sheep. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12917-022-03373-7.