Pig Milk Exosome Packaging ssc-miR-22-3p Alleviates Pig Intestinal Epithelial Cell Injury and Inflammatory Response by Targeting MAPK14

Inflammatory diseases of the intestinal tract in piglets severely impair the economic performance of pig farms. Pig milk exosomes can encapsulate miRNAs which can then enter the piglet intestine to play an immunomodulatory role. Previously, we comparatively analyzed and identified exosomal miRNAs in the colostrum and mature milk of Bamei and Landrace pigs, and we screened for ssc-miR-22-3p, which is associated with inflammation and immune response; however, the role played by ssc-miR-22-3p in the immune response in IPEC-J2 cells is not yet clear. In this study, we first constructed a pig intestinal inflammatory response model using Lipopolysaccharide (LPS) and Polyinosinic-polycytidylic acid (Poly (I:C)), and we investigated the role of ssc-miR-22-3p targeting <i>MAPK14</i> in the regulation of LPS and Poly (I:C)-induced inflammatory injury in IPEC-J2 cells by RT-qPCR, cell counting kit-8 (CCK-8), EdU staining, lactate dehydrogenase (LDH) activity assay, and dual luciferase reporter gene assay. We successfully established LPS and Poly (I:C)-induced cell damage models in IPEC-J2 cells. The immune response of IPEC-J2 cells was stimulated by induction of IPEC-J2 cells at 10 μg/mL LPS and 20 μg/mL Poly (I:C) for 24 h. Overexpression of ssc-miR-22-3p decreased cytokine expression and promoted cell viability and proliferation. The functional enrichment analysis revealed that ssc-miR-22-3p targets genes enriched in the pathways of negative regulation of inflammatory response and bacterial invasion of epithelial cells. The validity of the binding site of ssc-miR-22-3p to <i>MAPK14</i> was tested by a dual luciferase reporter gene. Pig milk exosome ssc-miR-22-3p promotes cell viability and proliferation by targeting <i>MAPK14</i>, and it alleviates LPS and Poly (I:C)-induced inflammatory responses in IPEC-J2 cells.