Bach Horacio, Ko Hin Hin, Raizman Eran A, Attarian Rodgoun, Cho Brian, Biet Franck, Enns Robert, Bressler Brian
Department of Medicine, Division of Infectious Diseases, University of British Columbia, Vancouver, British Columbia, Canada.
Scand J Gastroenterol. 2011 Jan;46(1):30-9. doi: 10.3109/00365521.2010.513061. Epub 2010 Aug 24.
The association between Mycobacterium avium subsp. paratuberculosis (MAP) and Crohn's disease (CD) is supported by several studies reporting the detection or isolation of MAP from human tissues, but a direct association is still debatable.
To evaluate the survival of MAP in human intestinal cells and to measure the presence of antibodies against two mycobacterial proteins necessary for the survival of the bacterium in the sera of CD patients.
Human-derived intestinal cells were infected with three isolates of MAP and the survival of the microorganism was determined. The presence of antibodies against protein tyrosine phosphatase A (PtpA) and protein kinase G (two proteins secreted within the host in the early stages of the invasion) in the sera of CD patients was evaluated. Sera of 20 CD patients and 20 controls were collected and the presence of the antibodies was assayed using enzyme-linked immunosorbent assay (ELISA). Secretion of the PtpA in vivo was visualized by immunostaining.
MAP survived in intestinal cells, and immunostaining of PtpA showed that the protein was secreted within these cells. Wilcoxon rank sum test revealed that CD patient sera had significantly higher titer of antibodies specific for both of these antigens compared to controls. ELISA results for either protein were not statistically different between men and women.
The presence of specific antibodies against mycobacterial proteins essential for establishing an infection in the host suggests that MAP can potentially be active in CD patients, and a serological test can be developed for early detection of MAP in CD patients.
多项研究报告了从人体组织中检测或分离出副结核分枝杆菌（MAP），支持了其与克罗恩病（CD）之间的关联，但直接关联仍存在争议。
评估MAP在人肠道细胞中的存活情况，并检测克罗恩病患者血清中针对该细菌存活所必需的两种分枝杆菌蛋白的抗体。
用三株MAP分离株感染人源肠道细胞，测定微生物的存活情况。评估克罗恩病患者血清中针对蛋白酪氨酸磷酸酶A（PtpA）和蛋白激酶G（入侵早期在宿主体内分泌的两种蛋白）的抗体。收集20例克罗恩病患者和20例对照的血清，采用酶联免疫吸附测定法（ELISA）检测抗体。通过免疫染色观察PtpA在体内的分泌情况。
MAP在肠道细胞中存活，PtpA的免疫染色显示该蛋白在这些细胞内分泌。威尔科克森秩和检验显示，与对照组相比，克罗恩病患者血清中针对这两种抗原的特异性抗体滴度显著更高。两种蛋白的ELISA结果在男性和女性之间无统计学差异。
存在针对在宿主体内建立感染所必需的分枝杆菌蛋白的特异性抗体，表明MAP可能在克罗恩病患者中具有活性，并且可以开发一种血清学检测方法用于早期检测克罗恩病患者中的MAP。
