Phospholipase A₂ Activity of Colonic Mucosa in Patients with Ulcerative Colitis

Abstract

Activation of enzyme phospholipase A₂ (EC 3.1.1.4), the major liberator of arachidonic acid, has been proposed as a component in the pathogenesis of inflammatory bowel disease. To test the hypothesis that phospholipase A₂ activity is increased in ulcerative colitis, enzyme activity was investigated in colonic biopsies using radiolabelled Escherichia coli as substrate. The study comprised patients with ulcerative colitis (n = 19) and controls without inflammatory bowel disease (n = 7). Ulcerative colitis patients were grouped into those with active disease (n = 8) and those in remission (n = 11) at the time of colonoscopy. No differences were found in mucosal phospholipase A₂ activity between patients with active disease, patients in remission and controls. With the present assay we were unable to demonstrate activation of phospholipase A₂ as a mechanism in the inflammatory process of ulcerative colitis.

Alterations of phospholipid concentration and species composition of the intestinal mucus barrier in ulcerative colitis: A clue to pathogenesis

“…Previous studies show that the activity of phospholipase A 2 (PLA 2 ) was elevated in patients suffering from IBD. 57,58 It is known that several types of phospholipases exhibit different selectivity for fatty acids at the sn-2 position and for the type of chemical bond at the sn-1 position. Phospholipase A can be found, for example, as a constituent in the membrane of Gramnegative bacteria.…”

“…The homeostasis of PC and LPC is of great importance in regulating the permeability of the intestinal epithelium. 57,58 LPC may promote inflammatory effects such as expression of endothelial cell adhesion molecules, growth factors, chemotaxis, and activation of monocytes/macrophages. 59 Since the sums of PC and LPC were likewise diminished in the mucus from UC patients compared to the other 2 groups, a deficit of PC in UC cannot be solely explained by an increase in enzymatic degradation.…”

Phospholipid turnover in the inflamed intestinal mucosa: Arachidonic acid-rich phosphatidyl/plasmenyl-ethanolamine in the mucosa in inflammatory bowel disease

“…Olaison et al 12 demonstrated PLaseA2 activation in the mucosae of CD patients who had experienced a symptomatic ileal recurrence within the previous year. On the other hand, Almer et al 13 found no PLaseA2 activation in UC mucosa. In these studies, PLaseA2 activity was determined by the release of radiolabelled fatty acids from synthetic phosphoglycerides or radiolabelled bacterial cells (E. coli) added to the reaction mixture.…”

“…It is of interest that metabolism in cellular organelles, such as peroxisomes, was enhanced in CD mucosa, but was suppressed in UC mucosa. Regarding PLaseA2 activity in the mucosa of IBD patients, Olaison et al 12 and Almer et al 13 examined PLaseA2 activity using radiolabelled Escherichia coli as a substrate. Olaison et al 12 demonstrated PLaseA2 activation in the mucosae of CD patients who had experienced a symptomatic ileal recurrence within the previous year.…”

Physiological Significance of Lysophospholipids that Act on the Lumen Side of Mammalian Lower Digestive Tracts

“…66) High expression of sPLA 2 II in the colon mucosa of patients with Crohn's disease and ulcerative colitis was also reported. 68,69) …”