This study aimed to assess immunopathological factors and M. hyopneumoniae (M. hyo) load in macroscopic lesion formation at four timepoints after experimental infection of swine. To do this, 24 M. hyo-free pigs were divided into two groups: non-inoculated control (n = 8) and inoculated (n = 16). At day 0 post-infection (dpi), animals of infected group were intratracheally inoculated with 5 mL of lung inoculum containing 107 CCU (Color Changing Units) ∕mL of M. hyo strain 232, while control group was mock infected with 5 mL of sterilized Friis medium. At 14, 28, 42 and 56 dpi, four animals from the infected group and two from the control group were euthanized and necropsied. The extent of macroscopic lung lobe lesions was visually assessed, scored and lesion samples (qPCR, histopathology and gene expression) were collected. The macroscopic lesion score and estimated M. hyo load (in copies/μL) at the different timepoints were: 14 dpi: 18.5 %-1.55 × 103 copies∕μL; 28dpi: 15.8 %-8.4 × 103 copies∕μL; 42 dpi: 7.0 %-3.2 × 104 copies∕μL and 56 dpi: 6.3 %-1.11 × 105 copies∕μL; Significant and positive correlations between macroscopic lung lesion and the pathogen load were found (coefficient range: 0.77-0.99). The cytokine's IL-6 (0.73) and INF-γ (-0.69) gene expression were significantly (p < 0.05) correlated to macroscopic lung lesion score while IL-8, TNF- α, IL-1α and IL-1β were associated to other pathological effects such as losses in average daily weight gain and microscopic lesion score. The results provide a better understanding about the pathogenicity of M. hyo strain 232 and the host-pathogen interactions, which may be helpful for the development of new treatments or control measures.

中文翻译：

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实验接种猪肺部病变发展过程中的细胞因子表达和猪肺炎支原体负担。

这项研究旨在评估免疫病理因素和猪肺炎支原体（M. hyo）在实验性感染猪后四个时间点在宏观病变形成中的负荷。为此，将24只无猪肺炎支原体的猪分为两组：未接种的对照（n = 8）和未接种的（n = 16）。感染后第0天（dpi），向感染组的动物气管内接种5 mL含107 CCU（颜色变化单位）∕ mL猪肺炎支原体菌株232的肺接种物，而对照组则模拟接种5 mL肺炎支原体。无菌Friis培养基。在14、28、42和56 dpi时，对感染组的四只动物和对照组的两只动物进行安乐死并进行尸检。肉眼评估宏观肺叶病变的程度，评分并收集病变样品（qPCR，组织病理学和基因表达）。在不同时间点的宏观病变评分和估计的M. hyo负荷（以份/μL为单位）为：14 dpi：18.5％-1.55×103份∕ L；28dpi：15.8％-8.4×103拷贝∕ L; 42 dpi：7.0％-3.2×104拷贝∕μL和56 dpi：6.3％-1.11×105拷贝∕μL; 发现宏观肺部病变与病原体负荷之间存在显着正相关（系数范围：0.77-0.99）。细胞因子的IL-6（0.73）和INF-γ（-0.69）基因表达与宏观肺损伤评分显着相关（p <0.05），而IL-8，TNF-α，IL-1α和IL-1β相关。其他病理影响，例如平均日增重和微观病变评分的降低。结果提供了对M. hyo菌株232的致病性和宿主-病原体相互作用的更好的理解，