Aims: A defective mucus composition represents a key pathogenetic factor for intestinal
injury. Phosphatidylcholine (PC) is an essential component contributing to formation
of a hydrophobic mucus layer. For evaluation of phosphatidylcholine in the pathogenesis
of inflammatory bowel disease, the concentration and composition of PC in the rectal
mucus of patients with ulcerative colitis was determined. Electrospray ionization
(ESI) tandem mass spectrometry (MS/MS) allows quantification of phosphatidylcholine
species and enables us to analyze crude extracts. Methods: Lipid extracts of material obtained by light scrapings of the intestinal lumen were
analyzed by nano-ESI MS/MS and with internal standardization quantified. PC and LPC
species from rectoscopically acquired mucus aliquots of patients with ulcerative colitis
(clinical remission) were compared to patients with Crohn's disease (clinical remission)
and control subjects. Results: Patients with inactive ulcerative colitis showed significant less PC and LPC (median
346 [IQR: 230–405] pmol total PC/ mg dry weight) in rectal mucus compared to Crohn's
disease (median 1126 [IQR: 465–1941] pmol total PC/ mg dry weight) and control subjects
(median 1285 [IQR: 850–1639] pmol total PC/ mg dry weight) (p?<? 0.05). The molecular
species of PC and LPC were not significant different in both groups. The most abundant
species were PC 16: 0/18: 1; PC 16: 0/18: 2; PC 18: 0/18: 1; PC 18: 0/18: 2; LPC 16:
0; and LPC 18: 0. Conclusion: NanoESI MS/MS is a suitable tool to analyze and quantify small amounts of PC in human
mucus. Patients with ulcerative colitis have significant less PC in their intestinal
mucus despite a comparable PC molecular species composition pattern. This indicates
that a low amount of protective mucus PC is a characteristic feature in ulcerative
colitis and may predispose to an impaired mucosal barrier function facilitating inflammatory
attacks by noxious colonic contents.
Schlüsselwörter
Inflammatory bowel disease - Mucus - Phospholipids
