Expressions of cyclooxygenase-2 and 5-1ipoxygenase in colonic mucosa of ulcerative colitis and the relationship between them

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Objective To investigate the expressions of cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) in colonic mucosa of patients with ulcerative colitis (UC)and to analyze the relationship between them. Methods The specimens of colonic mucosa from 32 UC patients were graded according to endoscopic and histological grading standards, and specimens of colonic mucosa from 26 healthy controls were also collected. The expressions of COX-2 and 5-LOX mRNA and protein in colonic mucosa were determined using real-time fluorescent quantitative reverse transcription polymerase chain reaction(RT-PCR) and immunohistochemistry. The correlation between COX-2 and 5-LOX was analyzed. Results For UC patients,10 were class 1, 19 class 2 and 3 class 3 according to endoscopic grading, whereas 19 were class Ⅰ , 9 class Ⅱ and 4 class Ⅲ according to histological grading. The expressions of COX-2 and 5-LOX mRNA in active UC patients were 81. 25% and 53.13%, respectively, and were 11.54% and 19. 23% in healthy controls, respectively, with significant differences between the two groups (all P values＜0.01). The positive expressions of COX2 and 5-LOX increased in accordance with increasing of endoscopic grading and histological grading.The levels of COX-2 and 5-LOX were 20. 08±1.17 and 37.83 ±1.48 in colonic mucosa tissues of UC patients, respectively, and 48.42 ± 1.69 and 11.28 ± 1.62 in healthy controls, respectively. There was significant difference between the two groups (all P values＜0.05). A good positive correlation was found between COX-2 and 5-LOX. Conclusions The expressions of COX-2 is closely related to 5-LOX in UC patients. Both may play a pivotal role in inflammation of UC. Key words: Colitis,ulcerative; Cyclooxygenase-2; Arachidonate 5-lipoxygenase; Reverse transcription polymerase chain reaction; Immunohistochemistry