WS Mycobacterium avium subspecies paratuberculosis serum lipid profile analysis through Fourier transform ion cyclotron resonance mass spectrometry

Abstract Text: Mycobacterium avium subspecies paratuberculosis (MAP) is responsible for Johne’s disease (paratuberculosis; paraTB) in bovine which elicits serve enteritis in the lower intestinal tract; similar to Crohn’s disease in humans. The objective of our study was to observe lipid changes in serum extracts of cattle infected with MAP using ultra-high resolution mass spectrometry. We hypothesized through the use of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) the identification of unique lipid biomarkers induced by MAP infection will be observed. Field samples from cattle infected with MAP (INF; n=10) were provided by the National Animal Disease Center (NADC). Uninfected serum (SC2012 and SC2015) from cattle with no history of paraTB came from two sources provided by the NADC. Negative controls used to test cross reactivity, with no MAP infection or previous exposure, included serum extracts from cattle challenged with lipopolysaccharide (LPS) and cattle infected with Mycobacterium bovis (bTB). Spectral differences were observed in the INF treatment compared to all other samples. Heteroatom class distribution, in positive ion mode, showed higher relative lipid abundance in the INF treatment in O₅Na₁, O₃, O₉Na₁, O₁₀Na₁, O₈Na₁, N₁, O₇Na₁, and N₁O₁ compounds whereas N₁O₈P₁ and N₁O₇P₁, were higher abundance in both control treatment groups. In negative-ion mode, O₃ compounds were greater relative abundance in the INF treatment and both control treatments had higher relative abundance of N₁O₁₁P₁ and O₁₃S₁compounds. Assigned elemental compositions were searched in the Lipidomic Gateway Databased to identify relative abundance of lipid classes. The majority of compounds classified in the glycerophospholipid, polyketide, or sterol class. Bioinformatics showed forty-five unique compounds (P < 0.05), twenty-six in positive-ion mode and nineteen in negative-ion mode, purely present in MAP infected cattle; no cross reactivity observed. The shift in heteroatom class distribution provides specific lipids may be present only in paraTB infected cattle, which is confirmed by the compounds identified solely in MAP infected cattle.

Keywords: Johne’s disease, paratuberculosis, Mycobacterium avium subspecies paratuberculosis, ultra-high resoltuion mass spectrometry, lipidomics