Fecal extract from obese horses induces an inflammatory response by murine macrophages in vitro

OBJECTIVE To compare the inflammatory response of murine macrophages exposed to the enteric microbiome of obese horses versus nonobese horses. SAMPLE Fecal samples from 12 obese horses (body condition score >= 7/9) and 12 nonobese horses (body condition score 4 to 5/9) with similar dietary management. PROCEDURES Fecal supernatant was prepared from frozen fecal samples. RAW 264.7 macrophage cells were exposed to the fecal extract. Inflammatory cytokine (interleukin-1 beta, tumor necrosis factor-alpha, and interleukin-6) gene expression was quantified via real-time quantitative reverse transcription PCR assay, and cytokine concentration was quantified via ELISA. Lipopolysaccharide was evaluated in fecal extract via chromo-limulus a moebocyte lysate assay. RESULTS Compared with fecal extracts from nonobese horses, fecal extracts from obese horses presented higher concentrations of lipopolysaccharide and induced a heightened expression of the proinflammatory cytokines interleukin-1 beta, tumor necrosis factor-alpha, and interleukin-6 from macrophages.