Interleukin-6 genetic ablation protects from trinitrobenzene sulfonic acid-induced colitis in mice. Putative effect of antiinflammatory cytokines.
BACKGROUND
Interleukin (IL)-6 is a proinflammatory cytokine implicated in the pathogenesis of inflammatory bowel disease. IL-6 is locally upregulated in inflammatory bowel disease patients and in murine models of experimental colitis. Treatment with anti-IL-6 receptor antibody ameliorates intestinal inflammation.


OBJECTIVE
It was the aim of this study to investigate the role of genetic IL-6 deficiency in trinitrobenzene sulfonic acid (TNBS)-mediated colitis, an experimental model inflammation that shares several features with Crohn's disease in humans.


METHODS
Acute colitis was induced in wild-type and IL-6-deficient (Il-6(-/-)) mice by intracolonic administration of TNBS. Forty-eight hours after treatment, the local and systemic features of inflammation, i.e. food intake, weight loss, histological markers of colitis, cytokine expression by real-time PCR, food intake and body weight changes, were assessed.


RESULTS
In wild-type mice, TNBS administration increased both IL-6 serum levels and local expression of IL-6 by 36 and 9 fold, respectively, compared with control, vehicle-injected mice. Compared with the wild-type mice, the Il-6(-/-) mice had significantly reduced intestinal inflammation as evidenced by epithelial damage, neutrophil infiltration, colon thickness and proinflammatory cytokine expression, following treatment with TNBS. Moreover, baseline levels of the antiinflammatory cytokines IL-10 and tumor growth factor-beta were significantly elevated in Il-6(-/-)compared with the wild-type mice.


CONCLUSIONS
Our results demonstrate that Il-6(-/-)are partially protected from the development of TNBS-induced acute experimental colitis, most likely via their significantly elevated baseline levels of antiinflammatory cytokines.
Gay
Jérôme
J
Division of Endocrinology, Children's Hospital, Boston, MA, USA.
Kokkotou
Efi
E
O'Brien
Michael
M
Pothoulakis
Charalabos
C
Karalis
Katia P
KP
D000818:Animals; D001835:Body Weight / Q000187:drug effects / Q000276:immunology; D002634:Chemotaxis, Leukocyte / Q000187:drug effects / Q000276:immunology; D003092:Colitis / Q000139:chemically induced / Q000235:genetics* / Q000276:immunology*; D003106:Colon / Q000276:immunology* / Q000473:pathology / Q000503:physiopathology; D004195:Disease Models, Animal; D004435:Eating / Q000187:drug effects / Q000276:immunology; D005260:Female; D016753:Interleukin-10 / Q000276:immunology / Q000378:metabolism*; D015850:Interleukin-6 / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016212:Transforming Growth Factor beta / Q000276:immunology / Q000378:metabolism*; D014302:Trinitrobenzenesulfonic Acid / Q000009:adverse effects; D015854:Up-Regulation / Q000187:drug effects / Q000276:immunology
D015850:Interleukin-6; D016212:Transforming Growth Factor beta; D016753:Interleukin-10; D014302:Trinitrobenzenesulfonic Acid