Background and aim: Interleukin (IL) 17 is a cytokine which exerts strong proinflammatory activities. In this study we evaluated changes in IL-17 expression in the inflamed mucosa and in the serum of patients with inflammatory bowel disease (IBD). Methods: Tissue samples were obtained endoscopically or surgically from patients with ulcerative colitis (UC) (n=20), Crohn's disease (CD) (n=20), infectious colitis (n=5), ischaemic colitis (n=8), and normal colorectal tissues (n=15). IL-17 expression was evaluated by a standard immunohistochemical procedure. Serum IL-17 levels were determined by ELISA. IL-17 mRNA expression was analysed by reverse transcriptase-polymerase chain reaction. Results: IL-17 expression was not detected in samples from normal colonic mucosa, infectious colitis, or ischaemic colitis. In the inflamed mucosa of active UC and CD patients, IL-17 expression was clearly detectable in CD3 + T cells or CD68 + monocytes/macrophages. The average number of IL-17 + cells was significantly increased in active UC and CD patients compared with inactive patients. IL-17 mRNA expression was not detected in normal mucosa but was detectable in the mucosa from active UC and CD patients. IL-17 was not detected in the sera from normal individuals, infectious colitis, or ischaemic colitis patients but IL-17 levels were significantly elevated in IBD patients. Conclusions: IL-17 expression in the mucosa and serum was increased in IBD patients. It is likely that IL-17 expression in IBD may be associated with altered immune and inflammatory responses in the intestinal mucosa.

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Colonic subepithelial myofibroblasts (SEMFs) may play a role in the modulation of mucosal inflammatory responses. We investigated the effects of interleukin (IL)-17 on IL-6 and chemokine [IL-8 and monocyte chemoattractant protein (MCP)-1] secretion in colonic SEMFs. Cytokine expression was determined by ELISA and Northern blotting. Nuclear factor kappa B (NF-kappaB) DNA-binding activity was evaluated by electrophortetic gel mobility shift assay (EMSA). The activation of mitogen-activated protein kinase (MAPK) was assessed by immunoblotting. IL-6, IL-8, and MCP-1 secretions were rapidly induced by IL-17. IL-17 induced NF-kappaB activation within 45 min after stimulation. A blockade of NF-kappaB activation markedly reduced these responses. MAPK inhibitors (SB-203580, PD-98059, and U-0126) significantly reduced the IL-17-induced IL-6 and chemokine secretion. The combination of either IL-17 + IL-1beta or IL-17 + tumor necrosis factor (TNF)-alpha enhanced cytokine secretion; in particular, the effects of IL-17 + TNF-alpha on IL-6 secretion were much stronger than the other responses. This was dependent on the enhancement of IL-6 mRNA stability. In conclusion, human SEMFs secreted IL-6, IL-8, and MCP-1 in response to IL-17. These responses might play an important role in the pathogenesis of gut inflammation.

In our mutation analyses of bilirubin UDP glycosyltransferase (UGT1A1) gene, we encountered six patients with Crigler-Najjar syndrome type II who were double homozygotes for G71R and Y486D, a patient with Gilbert's syndrome who was a single homozygote for G71R and six patients with Gilbert's syndrome who were single heterozygote for G71R. To clarify the role of each mutation in the occurrence of the two syndromes, we made four mutant expression models. Relative UGT1A1 activity of a single homozygous model of G71R was 32.2+/-1.6% of normal, that of a single homozygous model of Y486D was 7.6+/-0.5%, that of a double homozygous model of G71R and Y486D was 6.2+/-1.6% and that of a heterozygous model of G71R was 60.2+/-3.5%. The decreased activities of the single homozygous model of G71R and the double homozygous model were at an appropriate level to be diagnosed as Gilbert's syndrome and CN-II, respectively. The activity of a single heterozygous model of G71R was somewhat high to develop to the phenotype of Gilbert's syndrome, suggesting the presence of additional factors for the etiology of Gilbert's syndrome.

There is increasing evidence that IL-6 plays an important role in the pathophysiology of acute pancreatitis via its broad proinflammatory actions. To identify the local biosynthetic site for IL-6 in human pancreas, we investigated IL-6 secretion in human pancreatic periacinar myofibroblasts. IL-6 secretion was determined by ELISA and Northern blotting. The activation of NF-κB was assessed by EMSA. The activation of mitogen-activated protein kinase (MAPK) was assessed by immunoblotting. IL-6 secretion was rapidly induced by IL-17, IL-1β, and TNF-α. EMSAs demonstrated that IL-17, IL-1β, and TNF-α induced NF-κB activation within 1.5 h after stimulation, and a blockade of NF-κB activation by the pyrrolidine derivative of dithiocarbamate and tosyl-phe-chloromethylketone markedly reduced the IL-17-, IL-1β-, or TNF-α-induced IL-6 gene expression. Furthermore, IL-17, IL-1β, and TNF-α induced a rapid activation of extracellular signal-related kinase p42/44 and p38 MAPKs, and specific MAPK inhibitors (SB203580, PD98059, and U0216) significantly reduced IL-17-, IL-1β-, or TNF-α-induced IL-6 secretion, indicating the role of MAPKs in the induction of IL-6. The combination of either IL-17 plus IL-1β or IL-17 plus TNF-α enhanced IL-6 secretion and IL-6 mRNA expression; in particular, the effects of IL-17 plus TNF-α were much stronger than those induced by IL-17 plus IL-1β. TNF-α-induced IL-6 mRNA degraded rapidly at any concentrations, and the combination of IL-17 and TNF-α markedly enhanced IL-6 mRNA stability. This indicates that the effects of IL-17 plus TNF-α were regulated at the post-transcriptional level. In conclusion, pancreatic periacinar myofibroblasts secreted a large amount of IL-6 in response to proinflammatory cytokines. These cells might play an important role in the pathogenesis of acute pancreatitis via IL-6 secretion.