Department of Internal Medicine and Gastroenterology, S. Orsola-Malpighi Hospital, Via Massarenti 9, 40138, Bologna, Italy.
Dig Dis Sci. 2011 Oct;56(10):2957-62. doi: 10.1007/s10620-011-1699-6. Epub 2011 Apr 12.
Despite the increasing evidence of MAP/DNA isolation in Crohn's disease (CD), its potential pathogenetic role remains unclear. To further clarify the possible relationship between MAP and CD, we investigated the presence of IS900 DNA fragment in feces from Crohn's disease and ulcerative colitis (UC) patients and from healthy controls (HC).
Stool samples were collected from 31 CD, 20 UC, and 23 HC and stored at -20°C in 200-mg aliquots. DNA was extracted. MAP presence was detected with a specific PCR amplifying a 409-bp fragment from IS900. The specificity of PCR for IS900 was confirmed sequencing three positive products. Statistical analysis was performed using the Chi-square test.
Twenty-one of 31 CD (68%), 13 of 20 UC (65%) and 11 of 23 HC (48%) were MAP-positive (CD vs. HC: p = ns; UC vs. HC: p = ns). With the limits of a small sample size, the IS900-positive percentage in CD and UC was higher than HC, although the difference was not statistically significant.
The possibility to track the MAP presence in human feces represents a new approach to the "MAP hypothesis". Detection of MAP DNA in feces is very common, reaching very high prevalence both in CD and in UC and even in HC. Our findings seem consistent with a high prevalence of MAP asymptomatic infection among the general population and so the possible involvement of MAP in CD pathogenesis could be linked to a specific immune defective response.
尽管越来越多的证据表明 MAP/DNA 可从克罗恩病（CD）患者中分离出来，但它的潜在致病作用仍不清楚。为了进一步阐明 MAP 与 CD 之间可能的关系，我们检测了 CD、溃疡性结肠炎（UC）患者和健康对照者（HC）粪便中是否存在 IS900 DNA 片段。
收集 31 例 CD、20 例 UC 和 23 例 HC 的粪便样本，以 200mg 等分法储存在-20°C。提取 DNA。用特异性 PCR 扩增 IS900 中的 409bp 片段来检测 MAP 的存在。对三个阳性产物进行测序，以确认 PCR 对 IS900 的特异性。采用卡方检验进行统计学分析。
31 例 CD 中 21 例（68%）、20 例 UC 中 13 例（65%）和 23 例 HC 中 11 例（48%）为 MAP 阳性（CD 与 HC 相比：p=ns；UC 与 HC 相比：p=ns）。尽管差异无统计学意义，但 CD 和 UC 中 IS900 阳性百分比高于 HC，考虑到样本量小，这种情况可能提示 MAP 存在。
在粪便中追踪 MAP 存在的可能性代表了对“MAP 假说”的新研究方法。粪便中 MAP DNA 的检测非常普遍，在 CD 和 UC 中达到了非常高的流行率，甚至在 HC 中也是如此。我们的发现似乎与一般人群中 MAP 无症状感染的高流行率相一致，因此 MAP 可能参与 CD 发病机制与其特定的免疫缺陷反应有关。
