The Impact of TRIM67 Knockout on Early Intestinal Antimicrobial Capacity in Mice Infected with Salmonella enterica serovar Typhimurium ATCC 14028

<i>Salmonella enterica</i> serovar Typhimurium (<i>S.</i> Typhimurium) is an intracellular pathogen that survives and replicates within host cells. Macrophages, key immune cells in infection defense, play a vital role in pathogen clearance through polarization (M1/M2) and NLRP3 inflammasome activation. While <i>TRIM67</i> regulates macrophage recruitment in the liver, its role in <i>S.</i> Typhimurium infection remains unclear. In this study, a <i>S.</i> Typhimurium infection model was established by orally infecting streptomycin-pretreated <i>TRIM67</i> WT and KO mice with 1 × 10⁹ CFU of <i>S.</i> Typhimurium. <i>TRIM67</i> expression in the ileum, colon, mesenteric lymph nodes (MLNs), and peritoneal macrophages (PMs) was assessed via qRT-PCR and Western blotting. Histopathological changes were analyzed using HE and PAS staining. IHC staining, flow cytometry (FCM), qRT-PCR, and Western blotting were used to evaluate <i>TRIM67</i> knockout effects on macrophage recruitment, polarization, and NLRP3 inflammasome activation. In vitro, PMs were infected with <i>S.</i> Typhimurium (MOI 1:20), and <i>TRIM67</i>'s role in macrophage polarization and NLRP3 activation was validated. <i>S.</i> Typhimurium infection significantly upregulated <i>TRIM67</i> in the ileum, colon, and MLN. <i>TRIM67</i> knockout reduced intestinal inflammatory cell infiltration but worsened goblet cell loss and impaired digestion. Bacterial load assays revealed weakened pathogen clearance, leading to weight loss and increased mortality. <i>TRIM67</i> knockout inhibited intestinal macrophage recruitment, M1 polarization in MLN, and NLRP3 activation. In vitro, <i>TRIM67</i> knockout increased PMs' intracellular bacterial load and suppressed NLRP3, caspase-1, and IL-1β expression. <i>TRIM67</i> knockout impairs the host's ability to clear <i>S.</i> Typhimurium by inhibiting M1 macrophage polarization and NLRP3 inflammasome activation.