Serum Cytokine Reactions during Pregnancy in Healthy Mares

The aim of the research was to determine the differences in IL-1ß, IL-2, IL-4, IL-10, IL-17, INF-γ, TNF-α and IL-1ra blood concentrations in pregnant and non-pregnant healthy mares. The mares were divided into two groups: pregnant mares ( n = 18; age 6.11 ± 2.25 years); non-pregnant mares ( n = 6; age 5.67 ± 1.75 years). Blood samples were collected from all mares ( n = 24) three times every month, and then the pregnant group was divided into three subgroups based on the age of the pregnancy (1st group ( n = 6)—6th, 7th, 8th; 2nd ( n = 6)—7th, 8th, and 9th; 3rd ( n = 6)—8th, 9th, 10th month of pregnancy). The concentrations of IL-1ß, IL-2, IL-4, IL-10, IL-17, INF-γ, and TNF-α were higher in the pregnant than in non-pregnant group, whereas only the concentration of IL-1ra was lower in the pregnant than in the non-pregnant groups. Serum concentrations of proinflammatory cytokines such as IL-1 β, IL-2, and IFN-γ in pregnant mares were greater than in non-pregnant mares at the start of the trimester, whereas, IL-4, IL-17 and TNF-α started to rise in the latter months of the third trimester. IL-10 and IL-1ra concentrations started to decrease after the 6th month of pregnancy. In non-pregnant mares cytokine levels were stable during the whole study. In mares, the change in the ratio between Th1 (IL-1, IL-2, INF-γ, TNF-α) and Th2 (e.g., IL-4, IL-10, IL-13) cytokines occurs during pregnancy. The cytokine profile may be useful in the future for monitoring healthy pregnancies; however, more research is needed especially for miscarriage in mares.