CpG-ODN对S.aureus诱导的山羊实验性乳腺炎乳腺的保护作用研究

Protective effect of CPG-ODN on mammary gland of goat with mastitis induced by Staphylococcus aureus infection

选择同处于泌乳初期的睢宁白山羊6头,于右乳区经过乳导管灌注10μg/kgCpG-ODN,左乳区则灌入等体积的灭菌100μL0.01mol/LpH7.2磷酸盐缓冲液(PBS)作为对照,灌注后第3d按同等剂量进行二次灌注,二次灌注后第2d,分别于左右乳区经乳导管灌注3mL(2×109CFU/mL)金黄色葡萄球菌(S.aureus),于灌注细菌前(0h),灌注后8h,16h,24h,48h和72h分别收集左右乳区乳汁进行检测。临床症状观察显示,乳腺内灌注3mL(2×109CFU/mL)的S.aureus能迅速诱导山羊典型的急性乳腺炎症状。组织学观察显示感染S.aureus后72h乳腺腺泡内仍有嗜中性粒细胞(PMN)浸润,但实验乳区明显减少。乳汁S.aureus数同在感染后24h上升至最高,CpG-ODN能显著降低各个时间点乳汁细菌数。乳汁白细胞介素-6(IL-6)水平同在感染后24h上升至最高,CpG-ODN能显著提高感染后24h乳汁IL-6水平。对照和CpG-ODN处理乳区乳汁肿瘤坏死因子-α(TNF-α)水平分别在感染后24h和16h上升至最高,其中在感染后24h实验乳区比对照下降40.63%(P<0.05)。乳汁N-乙酰-β-D-氨基葡萄糖苷酶(NAGase)水平同在感染后16h达最高(P<0.01),CpG-ODN能显著提高感染后8h乳汁NAGase水平。上述结果表明CpG-ODN可通过提高乳汁IL-6水平、加速并促进乳汁TNF-α的释放,从而减少了乳汁中S.aureus数量,减轻了炎症介质对细胞的损伤,对缩短炎症过程也有一定的作用,实验结果证实了CpG-ODN对S.aureus感染诱发的山羊乳腺炎的乳腺有保护作用。

The protective effect of CpG-ODN on mastitis was evaluated in Suining white goats with mastitis induced by Staphylococcus aureus Infection. The goat mammary glands were treated with or without CpG-ODN followed by infection with S.aureus, Milk samples and mammary tissues were collected for bacteria counts and histopathologic examinations. The results showed that CpG-ODN treated mammary quarters had much lower bacteria counts in milk than controls at the different time points post-infection. The CpG-ODN could induce significant increase of IL-6 in milk at 24 h post-infection, and induce significant increase of NAGase in milk at 8 h post-infection. These results indicated that CpG-ODN fimctioned as an protective agent against mastitis by stimulating the production of IL-6, prompting the release of the TNF-α, reducing the bacteria counts in milk, attenuating the destruction of inflammation-mediator to cell and shortening the inflammation course.