Colonic expression and synthesis of interleukin 13 and interleukin 15 in inflammatory bowel disease.
A dysregulated local immune reaction with unbalanced cytokine expression seems essential in inflammatory bowel disease (IBD), i.e. ulcerative colitis (UC) and Crohn's disease (CD). Since the roles of interleukin (IL-)13 and IL-15 remain unclear, this study aimed at studying intestinal expression of IL-13 and IL-15 in IBD.


METHODS
In colonic biopsies from 24 UC, 18 CD, and 12 controls IL-13 and IL-15 were measured using ELISA, and their gene expressions were assessed by RT-PCR. Leukocytes were visualised histochemically.


RESULTS
Concentrations of IL-13 were decreased in UC (median 56 pg/mg tissue; interquartile range 30-99 pg/mg) compared to CD (82 pg/mg tissue; 41-122;P=0.004) and controls (83 pg/mg tissue; 18-134;P>0.05), and lower in active UC (53 pg/mg tissue; 33-96) than in inactive UC (80 pg/mg tissue; 65-99;P=0.02). IL-15 concentrations were higher in CD patients (34 pg/mg tissue; 24-53) as compared to controls (20 pg/mg tissue; 15-21;P=0.001) whilst being 22 pg/mg tissue (15-32) in UC. IL-13 mRNA and IL-15 mRNA were detected in 20% and 15%, respectively. Infiltration of leukocytes correlated inversely with IL-13 levels (P=0.02).


CONCLUSIONS
Active UC is associated with decreased colonic IL-13 suggesting that IL-13 levels are diminished as a part of UC exacerbations, or that exacerbations follow active downregulation of IL-13.
Vainer
B
B
Department of Medicine M, Division of Gastroenterology, Glostrup Hospital, University of Copenhagen, Denmark. ben.vainer@dadlnet.dk
Nielsen
O H
OH
Hendel
J
J
Horn
T
T
Kirman
I
I
D000328:Adult; D000368:Aged; D001706:Biopsy; D016022:Case-Control Studies; D003093:Colitis, Ulcerative / Q000175:diagnosis / Q000378:metabolism; D003106:Colon / Q000378:metabolism*; D003424:Crohn Disease / Q000175:diagnosis / Q000378:metabolism; D015536:Down-Regulation; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006098:Granulocytes / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D015212:Inflammatory Bowel Diseases / Q000175:diagnosis / Q000378:metabolism*; D018793:Interleukin-13 / Q000096:biosynthesis*; D019409:Interleukin-15 / Q000096:biosynthesis*; D007962:Leukocytes / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D020133:Reverse Transcriptase Polymerase Chain Reaction
D018793:Interleukin-13; D019409:Interleukin-15