Single-Cell Sequencing Analysis of PBMCs in Meishan Pigs: Comparative Insights from Normal Captivity to Arch Soil Free-Range Rearing

Free-range and confined feeding are typical farming strategies that produce vastly different outcomes in pig immune development. In this study, we extensively evaluated peripheral blood mononuclear cells (PBMCs) obtained from individually raised Meishan pigs under two distinct conditions: normal captivity (NC) and arch soil free-range (ASF), using single-cell sequencing technology. The purpose of this study was to elucidate the influence of various farming approaches on immune cell development. Our analysis identified 11 immune cell subtypes. Using differential gene analysis, we demonstrated that ASF produced the largest impact on the B cells and gamma delta T cell (γδ T cells) transcriptional profile, with subsequent impact on naïve CD4+ T cells and naïve CD8+ T cells. Based on our IL-16 network central analysis, relative to NC cells, signals obtained by B cells, effector and memory CD4+ T cells, and naïve CD4+ T cells were drastically diminished in the ASF cells. Additionally, we conducted an extensive network analysis using CellChat, and demonstrated a marked augmentation of axes related to cellular signal transduction and immunologic activity, including IL-16, RESISTIN, and MIF, among ASF cells. This indicated that various farming approaches differently impacted pig immune activity, and this process was primarily mediated by cell-cell communication. In conclusion, these findings not only enhance the available knowledge of the association between farming approaches and immune modulation, but also provide essential information for the sustainable establishment of animal husbandry and animal health management.