1 USDA-Agricultural Research Service (ARS), National Animal Disease Center, Ames, IA, USA.
Current affiliation: Department of Animal, Plant and Soil Sciences, Agribio Centre for Agribioscience, La Trobe University, Bundoora, Victoria, Australia.
Vet Pathol. 2019 Sep;56(5):671-680. doi: 10.1177/0300985819844823. Epub 2019 May 6.
Johne's disease is an enteric disease caused by the intracellular pathogen (MAP). Upon ingestion of MAP, it is translocated across the intestinal epithelium and may be killed by intestinal macrophages, or depending on the bacterial burden and immunological status of the animal, MAP may thwart innate defense mechanisms and persist within the macrophage. This study aimed to determine the numbers of macrophages and MAP present in bovine midileal tissue during different stages of infection. Immunofluorescent (IF) labeling was performed on frozen bovine midileal intestinal tissue collected from 28 Holstein dairy cows. The number of macrophages in midileal tissue sections was higher for clinically affected cows, followed by subclinically affected cows and then uninfected control cows. Macrophages were present throughout the tissue sections in clinical cows, including the tunica muscularis, submucosa, and the lamina propria around the crypts and in the villous tips, with progressively fewer macrophages in subclinically affected and control cows. Clinically affected cows also demonstrated significantly higher numbers of MAP and higher numbers of macrophages with intracellular MAP compared to subclinically affected cows. MAP IF labeling was present within the submucosa and lamina propria around the crypts, progressing into the villous tips in some clinically affected cows. Our findings indicate that number of macrophages increases with progression of infection, but a significant number of the macrophages present in the midileum are not associated with MAP.
约翰氏病是一种由细胞内病原体（MAP）引起的肠道疾病。MAP 被摄入后，会穿过肠上皮细胞，并可能被肠道巨噬细胞杀死，或者根据细菌负荷和动物的免疫状态，MAP 可能会破坏先天防御机制并在巨噬细胞内持续存在。本研究旨在确定在感染的不同阶段，牛中回肠组织中存在的巨噬细胞和 MAP 的数量。对从 28 头荷斯坦奶牛采集的冷冻牛中回肠肠组织进行免疫荧光（IF）标记。在临床受感染的奶牛中，回肠组织切片中的巨噬细胞数量更高，其次是亚临床受感染的奶牛，然后是未感染的对照奶牛。在临床奶牛的组织切片中，巨噬细胞存在于整个组织中，包括肌层、黏膜下层以及隐窝周围的固有层和绒毛尖端，而亚临床受感染和对照奶牛中的巨噬细胞则越来越少。临床受感染的奶牛还表现出明显更高数量的 MAP 和更多的具有细胞内 MAP 的巨噬细胞。MAP IF 标记存在于黏膜下层和隐窝周围的固有层中，在一些临床受感染的奶牛中进展到绒毛尖端。我们的发现表明，随着感染的进展，巨噬细胞的数量增加，但在回肠中存在的大量巨噬细胞与 MAP 无关。
