Influence Of Selenium On Immune-related Factors In Mastitis Induced By Staphylococcus Aureus In Rats

The research studied on influence of selenium (Se) on immune-related factors in mastitis induced by Staphylococcus aureus in rats. It is observed in the experiment including hematological changes, the histopathological changes, expression of mRNA and protein of TLR2 and the inflammatory cytokines.120 healthy pregnant Wistar rats, weighing 275±25 g, were randomly divided into control group (n=30, routine water), experimental groups (n=30, water with 0.2 mg/L sodium selenite), middle dose group(n=30, water with 0.4 mg/L sodium selenite), high dose group(n=30, water with 0.6 mg/L sodium selenite). the fourth pair of mammary glands of Each group were inoculated with 0.1 ml Staphylococcus aureus liquid (2×107 cfu/mL). Anticongulation blood samples, serum, and mammary glands were collected at 0h(before inoculated),6h,12h,24h and 48h(n=6). Experiments were conducted as follows:anticongulation blood samples detected with CBC; IFN-y, TNF-a, IL-1β, IL-6, IL-8 and IL-10 by ELISA; TLR2, TLR4,CCL5, CCL20, MCP-1 and PAFR by immunohistochemistry; mRNA expression of TLR2, IL-1β, IL-6, IL-8, IL-10, TNF-a, TGF-β1 and IFN-y in mammary tissue by qRT-PCR. The results were as follows:CD4+T in peripheral blood of high and middle dose groups increased significantly with dose dependent(P<0.05 or P<0.01). CD8+ T in peripheral blood of high dose group increased significantly at 12 h pi (P<0.05 or P<0.01). γδ+T in peripheral blood in low and middle dose groups increased significantly (P<0.01 or P<0.05). The amount of mast cell in lymphoglandulae inguinales and popliteal lymph node in low and middle dose groups increased significantly (P<0.05 or P<0.01) but the high group decreased significantly (P<0.05 or P< 0.01). The amount of macrophage in lymphoglandulae inguinales and popliteal lymph nodes in experimental groups increased significantly (P<0.05 or P<0.01).Contrase to control group, TLR2 in mammary tissue of experimental groups decreased significantly with increased dose of Se (P<0.01 or P<0.05). In middle groups, expression of CCL5 protein in mammary gland increased significantly (P<0.05 or P<0.01). In three experimental groups, CCL20, PAFR, and MCP-1 in mammary tissue became decreased significantly with dose dependent (P<0.01 or P<0.05). The protein expression of IL-6, IL-8 and IFN-y in serum in middle and high groups decreased significantly, but less opposite to the dose of Se (P<0.01 or P<0.05). The protein expression of IL-10 in serum in the three group increased significantly with dose-dependent of Se(P<0.01 or P<0.05).In the experimental groups, the mRNA expression of TLR2 showed a significant down-regulation with increased dose of Se(P<0.05 or P<0.01). TNF-α, IFN-γ, IL-1β, IL-6, and IL-8 in mammary of rats showed significant down-regulation with dose dependent (P< 0.01 or P<0.05). IL-10 in mammary of rats showed significant up-regulation with dose dependent(P<0.01 or P<0.05).In conclusions:Se was fed to rats with mastitis induced bystaphylococcus aureus. Gene and protein expression of TLR2 decreased with dose-dependent. In the meanwhile, Se inhibited the release and sythesis of cytokines with dose-dependent, including TNF-α, IL-1β, IL-6 and IL-8.IL-10, as anti-inflammatory cytokine, increased with dose-dependent, which could control the development of inflammation. So, Se additive could alleviate the damage during the inflammatory phase of mastitis.