PSLBI-29 - Gene expression patterns in liver tissue proximal to abscesses in cattle

Abstract: Liver abscesses pose a significant economic burden on the beef industry, resulting in substantial profit losses. A contributor to these losses is the decreased productivity and feed efficiency observed in affected cattle. Reduced feed efficiency could be attributed to the impairment of metabolic activity due to liver tissue damage caused by the abscesses. While tissue within the abscess itself is dysfunctional, little is known about the functional state of the surrounding liver tissue. Considering this, the present research aimed to evaluate liver tissue gene expression profiles at varying distances from liver abscesses. Tissue samples (n = 21) were collected from three distinct regions: 1) < 4 mm proximal from the abscess without including abscessed tissue (adjacent tissue), 2) 3 cm proximal from the abscess (nearby tissue), and 3) from livers with no abscesses (healthy controls). Gene expression comparisons utilizing DESeq were conducted between each tissue sample group. The number of differentially expressed genes (FDR ≤ 0.10) identified in each comparison is presented in Table 1. Tissue directly adjacent to the liver abscess was substantially different in gene expression when compared to both the healthy and tissue 3 cm proximal to an abscess. Fewer genes exhibited differential expression between healthy tissue and tissue taken 3 cm away. Gene enrichment analysis was conducted using the KOBAS-i software to identify biological pathways associated with the differentially expressed genes. Genes upregulated in liver tissue adjacent to the abscess were associated (FDR ≤ 0.10) with immune response pathways, including the "T cell receptor signaling pathway" and "Cytokine-Cytokine receptor interaction,” whereas downregulated genes were linked to metabolic pathways such as “Fatty Acid Metabolism" and multiple amino acid biosynthesis pathways. Gene expression differences between tissue 3 cm away and healthy tissue were minimal, however enrichment analysis identified significant (FDR ≤ 0.10) metabolic pathways such as the “peroxisome proliferator-activated receptor signaling” which is involved in gluconeogenesis and lipid metabolism, suggesting some metabolic alterations up to 3 cm proximal from the abscess. Upregulation of immune response pathways and downregulation of metabolic pathways in the adjacent tissue suggest a shift in cellular priorities, diverting resources to combat the active infection rather than routine metabolic processes. This localized immune response and metabolic dysregulation observed in the liver tissue adjacent to the abscess, coupled with metabolic alterations up to 3 cm away, highlight the effects of liver abscesses on the overall metabolic capacity and functionality of the liver. Continued research should focus on investigating the effect of abscess severity on overall liver function.