Lawsonia intracellularis, an obligate intracellular bacterium, is an important enteric pathogen in pig herds and horse farms worldwide. The hallmark feature of L. intracellularis infection is the proliferation of epithelial cells in intestinal crypts. A major limitation to the study of L. intracellularis infection is the lack of an in vitro model that reproduces the changes observed in proliferative enteropathy. Here we investigated the suitability of mouse enteroids as a model to study L. intracellularis infection. Mouse enteroids were microinjected with L. intracellularis, filter-sterilized L. intracellularis culture supernatant, or sterile cell culture media (DMEM). L. intracellularis antigen was detected in mouse enteroids by immunohistochemistry and was located mostly in the basal region of the epithelium. There was no differential growth of enteroids among treatment groups, and cellular proliferation was not increased in L. intracellularis-infected enteroids in relation to non-infected enteroids based on immunofluorescence staining. L. intracellularis infection did not induce changes in gene expression of Ki-67 (proliferation marker), Sox9 (marker for transit amplifying cells) and Muc2 (marker for goblet cells). These results indicate that although L. intracellularis antigen is detectable in mouse enteroids, indicating susceptibility to infection, mouse enteroids fail to replicate the cellular proliferation and gene expression changes observed in proliferative enteropathy. Nevertheless, we have successfully demonstrated that mouse enteroids can be used to model days-long intracellular pathogen infection, serving as potential models for the study of other pathogens of interest in veterinary medicine.

中文翻译：

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评价小鼠小肠作为细胞内劳森菌感染的模型。

细胞内劳森菌是一种专性的细胞内细菌，是全世界猪群和养马场的重要肠道病原体。细胞内劳森氏菌感染的标志性特征是肠隐窝中上皮细胞的增殖。对细胞内劳森氏菌感染的研究的主要局限性是缺乏体外模型，该模型无法再现在增生性肠病中观察到的变化。在这里，我们调查了小鼠小肠作为模型研究细胞内劳森氏菌感染的适用性。用细胞内劳森氏菌，过滤器灭菌的细胞内劳森氏菌培养物上清液或无菌细胞培养基（DMEM）显微注射小鼠小肠类固醇。细胞内劳森氏菌抗原通过免疫组织化学检测在小鼠小肠中，并且大部分位于上皮的基底区域。根据免疫荧光染色，与未感染的肠杆菌素相比，治疗组之间的肠杆菌素没有差异生长，并且细胞内劳森氏菌感染的肠杆菌素的细胞增殖没有增加。细胞内劳森氏菌感染并未诱导Ki-67（增殖标记），Sox9（转运扩增细胞的标记）和Muc2（杯状细胞的标记）的基因表达发生变化。这些结果表明，尽管在小鼠小肠中可检测到胞内劳森氏菌抗原，表明对感染易感，但小鼠小肠不能复制在增生性肠病中观察到的细胞增殖和基因表达变化。不过，我们已经成功地证明了小鼠小肠类固醇可用于模拟长达数天的细胞内病原体感染，