Aleksey Shakhov1, Larisa Sashnina1, Mariya Adodina1, Evgeniy Mikhaylov1, Mariya Zheynes1, Kristina Kopytina1, Mikhail Syromyatnikov1,2,3*

Abstract | The content of interleukins (IL-1β, IL-2, IL-4, IL-10), tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN -γ) in piglets blood serum in the early postnatal period was determined by the enzyme immunoassay (EIAs). In the colostrum of sows and the blood of pigs that did not suckle colostrum, the expression of the genes IL-1α, IL-10, actin proteins (reference gene) were determinate by real-time quantitative polymerase chain reaction (qPCR). The relative level of expression of the studied genes was carried out using 2 -∆∆Ct method. A high content of IL-1β, IL-2, IL-4, IL-10, TNF-α and IFN-γ cytokines was detected in colostrum of sows after farrow. It decreased in twenty-four hours and the levels of IL-1β and IL-10 with slight fluctuations remained in milk during the entire period of lactation, and IL-2 and TNF-α – up to 22 days, followed by a decrease in the amount of IL-2 and an increase in the content of TNF-α on day 26, respectively. The level of IL-4 and IFN-γ in comparison with the daily parameters ​​increased on days 7 and 14 with a decrease in their content at the end of lactation in sows. No expression of IL-1α, IL-10 and actin cytokine genes was detected in colostrum either due to the presence of a large amount of fat in it or the absence of living cells from which sufficient mRNA could be isolated. The expression of IL-1α cytokine gene and the presence of IL-1β, IL-2, IL-4, IL-10, TNF-α and IFN-γ were recorded in the newborns before obtaining colostrum, indicating their synthesis by fetal cells, the number of which increased in piglets at the age of twenty-four hours due to their intake with colostrum. The daily parameters of IL-1β, IL-10 and TNF-α with small fluctuations are maintained in piglets throughout the entire suckling period. The content of IL-2 in them during the first week of life and IL-4 at the age of twenty-four hours significantly increases with a subsequent decrease to days 14 and 22, respectively, and by the end of the suckling period of growth. The level of IFN-γ in piglets increases during the entire period of suckling, despite a significant decrease in its amount in milk, at the end of lactation of sows, which indicates the synthesis of cytokine by cells of their own immune system. Registration of the IL-1α gene and the presence of cytokines IL-1β, IL-2, IL-4, IL-10, TNF-α and IFN-γ in the blood serum of piglets before colostrum intake indicate their synthesis by fetal cells. The data obtained are recommended for use in assessing the immune status of healthy piglets and piglets with pathology, completeness of recovery of animals, prophylactic and therapeutic efficacy of immunomodulating drugs.

Keywords | Blood serum, Cytokine gene expression, Interleukin, Milk, Piglets