Monitoring mRNA transcription of genes involved in early pregnancy from endometrium and peripheral blood mononuclear cells of pregnant pigs with different parity.

The reproductive success of mammals is largely dependent on the interaction between maternal and foetal interfaces during early pregnancy. Particularly, immune cells which reside at the maternal endometrium can modulate the conception and placental vascularization. In this study, we analysed the transcription of genes involved in early pregnancy from endometrium and peripheral blood mononuclear cells (PBMCs) of pregnant pigs with different parity. Briefly, three groups of female pigs were divided based on parity (0, 2 and 5) and each group was artificially inseminated. Within 30 days of gestation, the total RNA was isolated from the endometrium and PBMCs of sacrificed experimental pigs and the expression patterns of genes involved in early pregnancy were monitored by quantitative real-time RT-PCR. Results indicated absence of correlation between increased parity and the expression of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1-α (HIF-1α) mRNA in endometrium among the groups of pigs analysed. Yet, the mRNA levels of Fas, Fas ligand (FasL) and tumour necrosis factor-α (TNF-α) in the endometrium of parity 5 sows were much higher than those of pregnant gilts (parity 0), and the mRNA ratios of both TNF-α:interleukin-4 (IL-4) and IFN-γ (interferon-γ):interleukin-10 (IL-10) in PBMCs of pregnant pigs were augmented with increasing parity. Furthermore, the mRNA levels of TNF-α and IFN-γ in PBMCs of pregnant pigs were inversely correlated with litter size. These combined results may demonstrate that increased parity of pregnant pigs leads to enhance Th1-prone immunity within the maternal-foetal interface during early pregnancy.