Decline in Serum Lysophosphatidylcholine Species in Patients with Severe Inflammatory Bowel Disease

<b>Background/Objectives</b>: Lysophosphatidylcholine (LPC) is composed of various lipid species, some of which exert pro-inflammatory and others anti-inflammatory activities. However, most of the LPC species analyzed to date are reduced in the serum of patients with inflammatory bowel disease (IBD) compared to healthy controls. To our knowledge, the correlation between serum LPC species levels and measures of inflammation, as well as their potential as markers for monitoring IBD activity, has not yet been investigated. <b>Methods</b>: Thirteen LPC species, varying in acyl chain length and number of double bonds, were measured in the serum of 16 controls and the serum of 57 patients with IBD. Associations with C-reactive protein (CRP) and fecal calprotectin levels as markers of IBD severity were assessed. <b>Results</b>: Serum levels of LPC species did not differ between the healthy controls and the entire patient cohort. In patients with IBD, serum levels of LPC 16:1, 18:0, 18:3, 20:3, and 20:5, as well as total LPC concentrations, showed inverse correlations with both CRP and fecal calprotectin levels, indicating an association with inflammatory activity. Nine LPC species were significantly reduced in patients with high fecal calprotectin compared to those with low values. LPC species with 22 carbon atoms and 4 to 6 double bonds were not related to disease activity. Stool consistency and gastrointestinal symptoms did not influence serum LPC profiles. Corticosteroid treatment was associated with lower serum LPC 20:3 and 22:5 levels, while mesalazine, anti-TNF, and anti-IL-12/23 therapies had no significant impact on LPC concentrations. There was a strong positive correlation between LPC species containing 15 to 18 carbon atoms and serum cholesterol, triglycerides, and phosphatidylcholine levels. However, there was no correlation with markers of liver disease. <b>Conclusions</b>: Shorter-chain LPC species are reduced in patients with active IBD and reflect underlying hypolipidemia. While these lipid alterations provide insight into IBD-associated metabolic changes, they appear unsuitable as diagnostic or disease monitoring biomarkers.