The effects of TGF-β1 on staphylococcus epidermidis biofilm formation in a tree shrew biomaterial-centered infection model

BACKGROUND: Transforming growth factor-β1 (TGF-β1) has a wide range of biological functions. It antagonizes lymphocyte response, inhibits pro-inflammatory cytokines, and serves as a signal to turn off the immune response and inflammatory response. To study the correlation between TGF-β1 and T helper (Th)1/Th2 cytokine levels in tree shrews, and to explore the effects of different levels of TGF-β1 on central venous catheter (CVC)-centered Staphylococcus epidermidis biofilm formation in tree shrews. METHODS: Tree shrews were injected with different concentrations of TGF-β1, and venous blood was drawn after 48 h to measure the levels of Th1 and Th2 cytokines. A CVC was placed into the femoral vein, and TGF-β1 at different concentrations and PIA− (ATCC12228) and PIA+ (ATCC35984) standard strains of Staphylococcus epidermidis were injected into the tree shrews to establish a biomaterial-centered infection (BCI) model. After 72 h, the CVC was removed, and biofilm formation was detected using the API bacterial identification system, semi-quantitative biofilm formation assay, and scanning electron microscopy. RESULTS: In the groups treated with TGF-β1 at different concentrations, the levels of Th1 cytokines interleukin-2 (IL-2), tumor necrosis factor (TNF), and interferon-γ (IFN-γ) were lower than those of normal group, while the levels of Th2 cytokines IL-6, IL-4 and IL-10 were higher than those of normal group. In the TGF-β1 groups at different concentrations, the positive rate of Staphylococcus epidermidis ATCC35984 biofilm formation was higher than that in non-TGF-β1 group, while there was no significant difference in the positive rate of Staphylococcus epidermidis ATCC12228 biofilm formation compared with that of the non-TGF-β1 group. CONCLUSIONS: TGF-β1 causes the imbalance of Th1/Th2 cytokines and Th1/Th2 shift in tree shrews, leading to Th1 cell-led decline in cellular immune function. TGF-β1 promotes PIA+ Staphylococcus epidermidis biofilm formation in the tree shrew BCI model, but it has no significant influence on PIA-Staphylococcus epidermidis biofilm formation on the surface of CVCs.