Relative abundance of interferon-stimulated genes STAT1, OAS1, CXCL10 and MX1 in ovine lymph nodes during early pregnancy.

Lymph nodes have functions in the adaptive immune response, and interferon-tau (IFNT), a primary pregnancy recognition signal in domestic ruminants has effects on immune regulation. It, however, is unclear whether early pregnancy induces an increase in the abundance of interferon-stimulated gene (ISG) mRNA transcripts and proteins in lymph nodes of sheep. In this study, lymph nodes were obtained on day 16 of the estrous cycle from non-pregnant ewes and days 13, 16 and 25 of gestation from pregnant ewes, and the abundance of ISG mRNA transcripts, including signal transducer and activator of transcription 1 (STAT1), phosphorylated STAT1 (p-STAT1), 2',5'-oligoadenylate synthetase (OAS1), myxovirus resistance protein 1 (MX1) and C-X-C motif chemokine 10 (CXCL10), was analyzed using real-time quantitative PCR. Furthermore, Western blot and immunohistochemistry analysis was conducted to assess relative abundance of proteins encoded by these genes. The results indicated that there was a larger abundance of STAT1 mRNA transcript and protein, and p-STAT1 protein in the maternal lymph node at days 16 and 25 of gestation, and that abundances of OAS1, MX1 and CXCL10 mRNA transcripts and protein were greatest on day 16 of gestations. In addition, STAT1 protein was located in the subcapsular sinus, lymph sinuses, B cells and T cells. The larger relative abundances of STAT1, p-STAT1, OAS1, MX1 and CXCL10 mRNA transcripts and/or protein in the lymph nodes of ewes may be associated with maternal immunoregulation through blood circulation and lymph circulation during early pregnancy.