Dynamic changes in peripheral blood CD4+ T cell subsets are associated with litter performance in primiparous gestating sows.

This study aimed to investigate the dynamic changes in peripheral blood CD4+ T cells and their association with litter performance in primiparous gestating sows. Blood samples were collected from 72 Large White × Landrace crossbred primiparous sows on the day of mating (G0), and on days 30 (G30), G60, G90, and G110 of gestation, and were analyzed for levels of CD4+ T cell subsets include T helper 1 cells (Th1), T helper 17 cells (Th17), regulatory T cells (Tregs), and related cytokines, such as interferon-gamma (IFN-γ), interleukin-12 (IL-12), IL-4, IL-5, IL-17A, IL-22, and IL-10, Transforming growth factor-beta (TGF-β) and reproductive hormones pregn-4-ene-3,20-dione (P4) and Estra-1,3,5 (10)-triene-3,17β-diol (E2). Results showed that Th1 and Th17 levels increased during early gestation (G0 ~ G30) and late gestation (G90 ~ G110) but decreased in middle gestation (G60), with their typical cytokines (IFN-γ, IL-12, and IL-17A) following a broadly similar pattern. P4 concentrations increased significantly following conception and remained elevated throughout gestation. In contrast, E2 levels began to rise markedly from G90 and peaked on G110. Tregs progressively expended throughout gestation, with the typical cytokine (TGF-β) displaying a broadly similar pattern of change, while IL-10 showed a transient decrease on G60. Pearson correlation analysis revealed that the levels of Th1 and Th17 cells, as well as their typical cytokines IFN-γ, IL-12, IL-17A, and IL-22 on G30 and G60, were negatively correlated with the number of total births and bore alive (r = -0.53 ~ -0.86, P < 0.01), while the level of Tregs and its typical cytokines IL-10 and TGF-β on G30 and G60 was positively correlated with the number of total births and live births (r = 0.35 ~ 0.86, P < 0.01) and negatively correlated with the number of mummified fetuses (r = -0.43 ~ -0.50, P < 0.01). The level of Th1 cells and its typical cytokines IFN-γ and IL-12 on G110 was positively correlated with the number of stillbirths (r = 0.37 ~ 0.75, P < 0.01), while the level of Tregs on G90 and G110 was negatively correlated with the number of stillbirths (r = -0.38 ~ -0.41, P < 0.01) and positively correlated with piglet birth weight (r = 0.79 ~ 0.82, P < 0.01). In conclusion, our study revealed dynamic changes in CD4+ T cell subsets in the peripheral blood of gestating sows. We also demonstrated the potential role of CD4+ T cells in predicting the reproductive performance of sows.