Imbalance of the interleukin 1 system in colonic mucosa--association with intestinal inflammation and interleukin 1 receptor antagonist [corrected] genotype 2.
BACKGROUND
Interleukin 1 (IL-1) alpha and beta are potent cytokines which play key roles in inflammation. They are controlled by IL-1 receptor antagonist (IL-1ra).


OBJECTIVE
To investigate the influence of mucosal inflammation and IL-1ra genotype on the IL-1ra:IL-1 balance.


METHODS
IL-1 alpha, IL-1 beta, and IL-1ra were measured by enzyme linked immunosorbent assay (ELISA) in biopsy specimens taken from inflamed and non-inflamed colon of 60 patients with Crohn's disease (CD), 34 with ulcerative colitis (UC), 15 inflammatory controls, and 103 non-inflamed controls. IL-1ra genotype was determined by polymerase chain reaction and gel electrophoresis.


RESULTS
IL-1 alpha and IL-1 beta were significantly increased in inflamed mucosa in inflammatory bowel disease (IBD) (CD: 53.5 (22.4) and 409.9 (118.7) pg/mg protein, respectively; UC: 18.9 (6.8) and 214.5 (78.2) pg/mg, respectively) and non-IBD patients (19.2 (7.4) and 281.4 (121.0) pg/mg, respectively; p < 0.0001) compared with normal controls (2.8 (0.6) and 30.6 (5.6) pg/mg, respectively). In CD IL-1 alpha and beta were also significantly increased in non-inflamed mucosa (6.1 (1.3) pg/mg and 88.7 (17.4) pg/mg, respectively; p < 0.0012). IL-1ra:(IL-1 alpha+beta) ratios were significantly decreased in inflamed mucosa of patients with CD (182 (45); p < 0.0001), UC (425 (136); p = 0.0018) and without IBD (221 (76); p < 0.0001), and in non-inflamed mucosa in CD (369 (149); p < 0.0001) compared with normal controls (1307 (245); p < 0.0001). Patients with IL-1ra genotype 2 had slightly but significantly reduced mucosal IL-1ra concentrations (p = 0.003). The greatest difference was seen in colonic biopsy specimens from patients with inflamed Crohn's disease.


CONCLUSIONS
Mucosal inflammation can modulate the balance of the IL-1:IL-1ra system in colonic mucosa.
Andus
T
T
Department of Internal Medicine I, University of Regensburg, Germany.
Daig
R
R
Vogl
D
D
Aschenbrenner
E
E
Lock
G
G
Hollerbach
S
S
Köllinger
M
M
Schölmerich
J
J
Gross
V
V
D000328:Adult; D003093:Colitis, Ulcerative / Q000276:immunology; D003106:Colon / Q000276:immunology*; D003424:Crohn Disease / Q000276:immunology; D004587:Electrophoresis, Agar Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005838:Genotype; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000276:immunology*; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1 / Q000032:analysis*; D007413:Intestinal Mucosa / Q000276:immunology*; D008297:Male; D016133:Polymerase Chain Reaction; D017472:Receptors, Interleukin-1 / Q000037:antagonists & inhibitors*; D012795:Sialoglycoproteins / Q000032:analysis / Q000235:genetics*
C507763:IL1RN protein, human; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1; D017472:Receptors, Interleukin-1; D012795:Sialoglycoproteins