鸡CD4+CD25+ T细胞在免疫耐受诱导中作用的研究

Poultry embryos are used as animal models widely in immunological studies because poultry embryos develop outside of matrix and B and T lymphocytes mature in different immune organs. Our previous studies show that micro-injection of foreign proteins via embyomic blood vessels can induce immune tolerance and chicken CD4+CD25+ T cells have the similar immune suppressive characteristics to CD4+CD25+ Foxp3+ T cells in mammals, but whether and how chicken CD4+CD25+ T cells play roles in the induction of immune tolerance have been not reported. In this study, we intend to induce immune tolerance via micro-injection of BSA at EID20, and detect humoral and cellular tolerance levels and analyse the correlation between CD4+CD25+ T cells and immune tolerance through flow cytometry; then we try to establish an approach to get low CD4+CD25+ T cell percentage chickens adopting micro-injection of anti-chicken CD25 antibodies via embryonic blood vessel; combined the chicken model of low CD4+CD25+ T cell percentage with immune tolerance model established before, we finally reveal the role of CD4+CD25+ T cells in the induction of immune tolerance in chicken. The results of this study can provide evidence for expound roles of CD4+CD25+ T cells in immune tolerance and a good animal model for studies of immunology, disease and treatment in chicken embryos.

禽类胚胎离开母体发育及B、T细胞独立发育的特点使其作为免疫学研究的动物模型被广泛应用。我们前期发现，鸡胚血管注射外源蛋白可诱导免疫耐受，且鸡CD4+CD25+T细胞具有和哺乳类中CD4+CD25+Foxp3+T细胞相似的免疫抑制特性，但该细胞群是否是鸡免疫耐受形成的细胞基础并不确定。本项目拟在鸡胚发育第20天注射牛血清白蛋白诱导出雏鸡对该外源蛋白的体液和细胞免疫耐受，并通过流式细胞术分析CD4+CD25+T细胞与耐受的相关性；进而建立一种胚胎发育第16天血管注射CD25单抗制备低CD4+CD25+T细胞比例鸡的方法；最后，检测分析在低CD4+CD25+T细胞比例的鸡中诱导的免疫耐受水平变化，探究鸡该细胞群在免疫耐受中的作用。本项目将阐明CD4+CD25+T细胞在免疫耐受中的作用，建立的低CD4+CD25+T细胞比例的鸡也将成为在鸡胚中研究免疫学、疾病发生和治疗等研究提供良好的动物模型。

鸡CD4+CD25+T细胞具有和哺乳类中相同的免疫调节功能，但其在免疫耐受中的作用并不明确。本项目在鸡胚发育第20天注射BSA可以改变B细胞产生抗体的水平和T细胞增殖反应，诱导出雏鸡对该蛋白的免疫耐受，但对BSA剂量有要求，本项目中0.75mg或1mgBSA都可以诱导出免疫耐受。免疫耐受形成过程中，CD4+CD25+T细胞在此过程中比例升高，说明了两者的相关性。胚胎发育第16天血管注射15ug CD25单抗可以形成低CD4+CD25+T细胞比例鸡，研究还发现了胚胎发育到中后期出现了一些具有差异性功能的肠道菌群定植。预先降低CD4+CD25+T细胞比例后，注射BSA诱导免疫耐受水平显著降低，揭示了CD4+CD25+T细胞在免疫耐受过程中发挥着不可或缺的作用。本项目的成果完善了禽类调节性T细胞功能的理论基础，为鸡胚在生物学研究中的应用提供了良好的动物模型，拓展和衍生研究也为禽类微生物制剂开发提供了思路和依据。