Johne's disease (JD) is a chronic inflammatory gastrointestinal disease of ruminants caused by Mycobacterium avium subspecies paratuberculosis (MAP). Control of JD is difficult largely due to insensitive diagnostic tools, a long subclinical stage of infection, and lack of effective vaccines. Correlates of protection are lacking in model systems of JD and the sources of inflammation due to JD are not well characterized. Commonly studied immune responses, such as the Th1/Th2 paradigm, do not adequately explain host responses to MAP. A potential role for non-classical immune responses to MAP, such as that mediated by Th17 cells, has been suggested. Indeed, MAP antigens induce mRNAs encoding the cytokines IL-23 and IL-17a in bovine peripheral blood mononuclear cells (PBMCs). IL-23 and IL-17a production have both been associated with Th17-like immune responses. Th17 cells are also defined by surface expression of the IL-23 receptor (IL-23R). To determine the relative prevalence of potential Th17 cells in PBMCs from MAP test positive and MAP test negative cows, PBMCs were isolated and analyzed by immunostaining and flow cytometry. Fresh PBMCs from MAP test positive cows (n = 12) contained a significantly higher proportion of IL-23R positive cells in populations of CD4+, CD8+, and Yδ + T cells than in cells from MAP test negative cows (n = 12; p < 0.05). Treatment with MAP antigens increased the percentage of all T cell subsets with surface expression of IL-23R when compared to untreated (n = 12; p < 0.05) cells. ELISA results for IL-17a secretion revealed a higher concentration of IL-17a secreted from PBMCs treated with MAP antigen (n = 20) than from PBMCs not treated with MAP antigens (n = 20) (p < 0.001), regardless of the JD test status of source cows. Also, we observed a moderate negative correlation between JD diagnostic scores for JD + cows and plasma IL-17a concentration (n = 42; r = -0.437; p-value < 0.004). Plasma with low and mid JD- scores (n = 31; n = 9; 0.1 ≤ X < 0.3) had significantly more IL-17a when compared to plasma with high JD- scores (n = 10; 0.3 ≤ X < 0.46; p-values < 0.05). Similarly, plasma with low JD + score values (0.55 ≤ X < 1.0; n = 9) had significantly more IL-17a when compared to plasma with high JD + score values (X ≥ 2.0; n = 21; p < 0.05). Overall, plasma from JD + cows (0.55 < X ≤ 2.86; n = 41) had significantly less IL-17a than plasma from JD- cows (0 < X ≤ 0.46; n = 70). Our data suggests that Th17-like cells may indeed play a role in early immune responses to MAP infection and development or control of JD.

中文翻译：

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鸟分枝杆菌 副结核病（MAP）诱导牛外周血单核细胞（PBMC）中IL-17a的产生，并增强IL-23R的体内和体外表达。

约翰尼病（JD）是由鸟分枝杆菌亚种副结核病（MAP）引起的反刍动物的慢性炎性胃肠道疾病。由于诊断工具不灵敏，亚临床感染期长以及缺乏有效的疫苗，因此很难控制JD。JD的模型系统缺乏相关的保护，并且由于JD引起的炎症来源尚未得到很好的表征。常用的免疫反应（例如Th1 / Th2范例）不能充分解释宿主对MAP的反应。已经提出了对MAP的非经典免疫应答的潜在作用，例如由Th17细胞介导的免疫应答。实际上，MAP抗原在牛外周血单核细胞（PBMC）中诱导了编码细胞因子IL-23和IL-17a的mRNA。IL-23和IL-17a的产生均与Th17样免疫反应有关。Th17细胞也由IL-23受体（IL-23R）的表面表达来定义。为了确定MAP测试阳性和MAP测试阴性奶牛的PBMC中潜在Th17细胞的相对患病率，分离PBMC并通过免疫染色和流式细胞术进行分析。来自MAP测试阳性奶牛（n = 12）的新鲜PBMC在CD4 +，CD8 +和Yδ+ T细胞群中所含的IL-23R阳性细胞比例明显高于MAP测试阴性奶牛（n = 12； p < 0.05）。与未处理的细胞（n = 12； p <0.05）相比，用MAP抗原治疗可增加所有带有IL-23R表面表达的T细胞亚群的百分比。ELISA法检测IL-17a分泌的结果显示，与未用MAP抗原处理的PBMC（n = 20）相比，用MAP抗原处理的PBMC（n = 20）分泌的IL-17a浓度更高（p <0.001），而与JD无关源奶牛的测试状态。此外，我们观察到JD +母牛的JD诊断评分与血浆IL-17a浓度之间存在中等程度的负相关（n = 42； r = -0.437； p值<0.004）。与具有高JD-分数（n = 10; 0.3≤X <0.46; p的血浆）相比，具有JD-分数中低（n = 31; n = 9; 0.1≤X <0.3）的血浆的IL-17a明显更高。 -值<0.05）。同样，与具有较高JD +得分值（X≥2.0； n = 21； p <0.05）的血浆相比，具有较低JD +得分值（0.55≤X <1.0； n = 9）的血浆的IL-17a明显更高。总体而言，来自JD +奶牛的血浆（0.55 <X≤2.86; n = 41）的IL-17a显着低于JD母牛的血浆（0 <X≤0.46; n = 70）。我们的数据表明，Th17样细胞可能确实在针对MAP感染和JD发生或控制的早期免疫反应中起作用。