Interferon Tau (IFNt) and Interferon-Stimulated Genes (ISGs) Expression in Peripheral Blood Leukocytes and Correlation with Circulating Pregnancy-Associated Glycoproteins (PAGs) during Peri-Implantation and Early Pregnancy in Buffalo Cows

Abstract

The objective of this study was to analyze interferon-stimulated genes (ISGs) and interferon tau (IFNt) gene expression in peripheral blood leukocytes during the peri-implantation period and until 40 days of pregnancy in buffalo cows. Relationships were also examined between the expression of ISGs and IFNt and pregnancy-associated glycoproteins (PAGs) peripheral plasma concentration. Buffalo cows were synchronized and artificially inseminated (d 0). Blood samples were collected on days 0, 18, 28 and 40 after artificial insemination (AI) for peripheral blood mononuclear cells (PBMCs) and polymorphonuclear leukocytes (PMNs) isolation and PAGs radioimmunoassay analysis. The study was carried out on 21 buffalo cows divided ex post into Pregnant (n = 12) and Non-pregnant (n = 9) groups. Steady state levels of OAS1, MX2, ISG15 and IFNt mRNA were measured by RT-qPCR and their estimated marginal means (p < 0.01 for all) were higher in pregnant than non-pregnant buffaloes, both in PBMCs and PMNs. In PBMCs, pairwise comparisons showed that OAS1 and MX2 expressions differed between pregnant and non-pregnant buffaloes on all the days of observation (p < 0.001), while significant differences in ISG15 and IFNt started from day 28 post-AI (p < 0.05). In PMNs, ISG15 expression differed between groups only at days 18 and 28 (p < 0.001), while comparisons were always significant for IFNt (p < 0.05). The expression of all genes, except ISG15 as determined in PMNs, was positively associated with PAGs plasma concentrations (p < 0.05). This work showed a significant increase in ISGs and IFNt expressions in PBMCs and PMNs in buffalo during the peri-implantation period and early pregnancy, and their correlation with PAGs plasma concentration.

Keywords: IFNt; PAGs; PBMCs; PMNs; buffalo; interferon-stimulated genes (ISGs); pregnancy.

Figure 1

OAS1, MX2, ISG15 and IFNt expression in PBMCs of pregnant and non–pregnant buffaloes. Asterisks indicate differences in expression between the Pregnant and Non-pregnant groups for each gene and each day post-artificial insemination (AI; * p < 0.05, ** p < 0.01, *** p < 0.001).

Figure 2

OAS1, MX2, ISG15 and IFNt expression in PMNs of pregnant and non–pregnant buffaloes. Asterisks indicate differences in expression between the Pregnant and Non-pregnant groups for each gene and each day post-artificial insemination (AI; ns: not significant, * p < 0.05, ** p < 0.01, *** p < 0.001).

Figure 3

OAS1, MX2, ISG15 and IFNt expression in polymorphonuclear leukocytes (PMNs) and mononuclear cells (PBMCs) of pregnant buffaloes. Asterisks indicate differences in expression between PBMCs and PMNs for each gene and each day post-artificial insemination (only significant differences are indicated; ** p < 0.01, *** p < 0.001).