Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE.
U.S. Meat Animal Research Center, USDA, ARS, Clay Center, NE.
J Anim Sci. 2020 Dec 1;98(12). doi: 10.1093/jas/skaa359.
Abscess is the highest cause of liver condemnation and is estimated to cost the beef industry US$64 million annually. Fusobacterium necrophorum, commonly found in the bovine rumen, is the primary bacteria associated with liver abscess in cattle. Theoretically, damage to the rumen wall allows F. necrophorum to invade the bloodstream and colonize the liver. The objective of this study was to determine the changes in gene expression in the rumen epithelium and microbial populations adherent to the rumen epithelium and in the rumen contents of beef cattle with liver abscesses compared with those with no liver abscesses. Rumen epithelial tissue and rumen content were collected from 31 steers and heifers with liver abscesses and 30 animals with no liver abscesses. Ribonucleic acid (RNA) sequencing was performed on the rumen epithelium, and a total of 221 genes were identified as differentially expressed in the animals with liver abscesses compared with animals with no abscesses, after removal of genes that were identified as a result of interaction with sex. The nuclear factor kappa-light-chain enhancer of activated B cells signaling and interferon signaling pathways were significantly enriched in the differentially expressed gene (DEG) set. The majority of the genes in these pathways were downregulated in animals with liver abscesses. In addition, RNA translation and protein processing genes were also downregulated, suggesting that protein synthesis may be compromised in animals with liver abscesses. The rumen content bacterial communities were significantly different from the rumen wall epimural bacterial communities. Permutational multivariate analysis of variance (PERMANOVA) analysis did not identify global differences in the microbiome of the rumen contents but did identify differences in the epimural bacterial communities on the rumen wall of animals without and with liver abscesses. In addition, associations between DEG and specific bacterial amplicon sequence variants of epimural bacteria were observed. The DEG and bacterial profile on the rumen papillae identified in this study may serve as a method to monitor animals with existing liver abscesses or to predict those that are more likely to develop liver abscesses.
脓肿是导致肝脏病变的主要原因，据估计每年给牛肉产业造成的损失达 6400 万美元。坏死梭杆菌是一种常见于牛瘤胃中的细菌，是与牛肝脏脓肿相关的主要细菌。理论上，瘤胃壁的损伤使坏死梭杆菌能够侵入血液并在肝脏中定植。本研究的目的是确定与无肝脓肿牛相比，患有肝脓肿牛的瘤胃上皮组织和附着在瘤胃上皮组织上的微生物群以及瘤胃液中的基因表达变化。从 31 头患有肝脓肿的阉牛和小母牛以及 30 头无肝脓肿的动物中采集瘤胃上皮组织和瘤胃液。对瘤胃上皮组织进行核糖核酸（RNA）测序，共鉴定出 221 个基因在患有肝脓肿的动物中与无脓肿的动物相比存在差异表达，这些基因是由于与性别相互作用而被鉴定出来的。在差异表达基因（DEG）集中，核因子 kappa 轻链增强子的 B 细胞激活信号和干扰素信号通路显著富集。这些通路中的大多数基因在患有肝脓肿的动物中下调。此外，RNA 翻译和蛋白质加工基因也下调，表明患有肝脓肿的动物的蛋白质合成可能受损。瘤胃液细菌群落与瘤胃壁上皮间细菌群落明显不同。可变性多元方差分析（PERMANOVA）分析未确定瘤胃液微生物组的全局差异，但确实确定了无肝脓肿和有肝脓肿动物瘤胃壁上皮间细菌群落的差异。此外，还观察到 DEG 与上皮间细菌特定扩增子序列变体之间的关联。本研究中鉴定的瘤胃乳头 DEG 和细菌图谱可作为监测现有肝脓肿动物或预测更可能发生肝脓肿动物的方法。
