Utility of Fatty Acid Profile of Erythrocyte Membrane in Identifying Diagnostic Markers of Crohnʼs Disease

Abstract

Introduction: We often experience cases of Crohn's disease (CD) that are hard to distinguish from other inflammatory bowel diseases (IBDs), such as ulcerative colitis (UC) and indeterminate colitis, making diagnosis difficult. We have previously reported that the erythrocyte membrane phospholipid fatty acid profile is very specific in patients with initial IBD, particularly CD. This suggests that the activity of enzymes involved in the metabolism of linoleic acid (LA) and palmitic acid (PA), namely, delta 6 desaturase and elongase 6, is expected to be higher than that of healthy individuals. In this study, we evaluated the utility of delta 6 desaturation index (Δ6di), elongation index (EI), and various fatty acids as diagnostic markers of CD. Methods: Ninety-five IBD patients (70 with CD and 25 with UC) and controls (90 healthy individuals) were enrolled in this study. We analyzed the erythrocyte membrane phospholipid fatty acid concentrations in each of these groups. As indexes of enzyme activity, we calculated the Δ6di using the percentage weights of LA, dihomo-γ-linoleic acid (DGLA), and arachidonic acid (AA), i.e., Δ6di=(DGLA+AA)/LA, and EI using the percentage weights of PA, stearic acid (SA), and oleic acid (OA), i.e., EI=(SA+OA)/PA. Results: In CD patients, the percentage weights of SA, DGLA, and AA were significantly higher, and those of PA and LA were significantly lower (p < 0.001), in comparison with those of UC patients and controls. Similarly, Δ6di and EI were significantly higher (p < 0.001). The areas under the receiver operating characteristic curve of Δ6di and SA were the highest at 0.920 and 0.922, respectively. When cut-off values of 1.325 and 13.27 were chosen for Δ6di and SA, respectively, the sensitivity and specificity for CD patients versus UC patients and controls were 91.4 and 87.8% for Δ6di and 82.9 and 99.1% for SA, respectively. Conclusion: In CD patients, the percentage weights of LA and PA were significantly lower, and those of AA and SA were significantly higher as compared to those of UC patients and controls. In addition, Δ6di and SA could be excellent diagnostic markers of CD.Figure 1