PS11-2. Characterizing Metabolic Gradients in Bovine Liver Tissue Across Abscess Proximity.

Abstract

The liver serves as the central hub of metabolic processes within the animal body. Bovine liver abscesses are theorized to impact metabolism and absorption of nutrients. This study aimed to determine if metabolic alterations occur in liver tissue located at varying distances between abscesses. Bovine livers (n = 20) were collected from a commercial harvest facility, and core samples were collected from tissue positioned at varying distances (1.27 to 7.83 cm) approximately equidistant between three abscesses. Untargeted primary metabolites were profiled using gas chromatography-mass spectrometry. A generalized additive model with spline smoothing was used to evaluate metabolite abundance and capture linear and non-linear spatial relationships across a distance gradient. Metabolites associated with carbohydrate metabolism (lactose-2, maltotriose, and melezitose) and oxidative energy-production (citric acid) increased (P £ 0.02) in a non-linear concentration with increasing distance from an abscess. This is suggestive of a shift from a pathogen-dominated, metabolically suppressed environment proximal to an abscess towards more physiologically normal metabolism in healthy liver tissue. A linear decrease (P £ 0.05) in metabolite concentration was observed for 2-aminobutyric acid, asparagine, cholesterone, citrulline, cyanoalanine, threonine, and valine. These metabolites indicate that bacterial metabolism adjacent to an abscess creates a shift into anaerobic pathways and tissue breakdown. Other metabolites (creatinine, lactic acid, phenylalanine, threonic acid, xanthine) exhibited subtle non-linear concentration reductions as distance from an abscess increased. Anaerobic metabolic changes are indicated through the drop in lactic acid levels at further distances from an abscess, which could indicate a normalization in liver tissue and aerobic glycolysis. A decrease in creatinine levels can indicate a decrease in protein breakdown as distance increases from an abscess. Oxidative stress was also observed to decrease further away from a liver abscess through the decrease of phenylalanine and threonic acid. In summary, liver tissue metabolites were indicative of tissue stress changes, inflammation, and liver failure signals. These data confirm a change in liver metabolism and oxidative stress levels, likely indicative of change in metabolic liver function associated with active liver abscesses.