[Animal modeling] - Establishment of mastitis model in mice infected with Staphylococcus aureus and changes of IL-2 and IL-4

  Objective: To investigate the changes of inflammatory factors interleukin 2 (IL-2) and interleukin 4 (IL-4) in the pathogenesis of mastitis in mice

  Methods: Twelve lactating female rats (BALB/C) were randomly divided into control group (Group A), high concentration group (Group B), medium concentration group (Group C) and low concentration group (Group D); Group B, C and D were injected with 1.2 × 105、1.2 × 104、6.0 × 103 CFU/mL Staphylococcus aureus of different concentrations. The pathological changes were observed by H&E staining, and the expression of IL-2 and IL-4 mRNA and protein levels in mouse mammary gland tissues were detected by qRT-PCR, immunohistochemistry and Western blot

  Results: H&E staining results showed that the pathological changes of breast tissue were gradually aggravated with the increase of the concentration of Staphylococcus aureus. It was found by immunohistochemistry, qRT-PCR and Western blot that the expression level of IL-2 in group B, C and D was significantly higher than that in group A (P<0.05), but the expression level decreased with the increase of the concentration of infectious bacteria. At the same time, the expression level of IL-4 in group B, C and D was significantly higher than that in group A (P<0.05), However, with the increase of the concentration of infectious bacteria, its expression level gradually increases

  Conclusion: Inflammatory factors IL-2 and IL-4 are involved in the occurrence of murine mastitis caused by Staphylococcus aureus, laying a foundation for the pathological mechanism of Staphylococcus aureus mastitis, and providing a scientific theoretical basis for the study of breast immune mechanism