Sanae Fujino

Increased expression of interleukin 17 in inflammatory bowel disease

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.

IL-17 Selectively Down-Regulates TNF-α-Induced RANTES Gene Expression in Human Colonic Subepithelial Myofibroblasts

IL-17 enhances the TNF-α-induced IL-6 and IL-8 secretion in human colonic subepithelial myofibroblasts. In this study, we investigated how IL-17 modulates RANTES secretion in these cells. TNF-α potently induced RANTES secretion, but IL-17 dose-dependently inhibited the TNF-α-induced RANTES secretion. This was also observed at the mRNA level. Even after pretreatment with TNF-α for 12 h, the inhibitory effect of IL-17 was detectable. IL-17 did not affect the TNF-α-induced stability of the RANTES gene. IL-17 significantly decreased the TNF-α-induced increase in RANTES promoter activity, and IL-17 actually blocked the TNF-α-induced RANTES gene transcription. EMSAs demonstrated that IL-17 did not modulate the TNF-α-induced NF-κB DNA-binding activity, but markedly decreased TNF-α-induced IFN regulatory factor-1 (IRF-1) DNA-binding activity. Because cooperation between NF-κB and IRF-1 is important in the TNF-α-induced RANTES gene expression, the major mechanism mediating the inhibitory effect of IL-17 may be achieved by the inhibition of IRF-1 DNA-binding activity.

Suppression of interleukin-1beta- and tumor necrosis factor-alpha-induced inflammatory responses by leukocytapheresis therapy in patients with ulcerative colitis.

BackgroundTo elucidate the molecular mechanisms involved in the therapeutic effects of leukocytapheresis (LCAP), we investigated the alterations in the cytokine responses of peripheral blood mononuclear cells (PBMCs) before and after LCAP therapy in ulcerative colitis (UC) patients.MethodsTwelve patients with UC who did not respond to steroid therapy were enrolled. Nine patients responded to LCAP therapy, but 3 patients did not show clinical improvement. PBMCs were isolated from peripheral venous blood obtained within 5 min before and after the first and second session of LCAP treatment. Cells were stimulated with interleukin (IL)-1β and tumor necrosis factor (TNF)-α for 24 h, and the levels of secreted IL-8 and IL-6 were determined by enzyme-linked immunosorbent assay (ELISA).ResultsLCAP induced a significant decrease in peripheral lymphocyte, monocyte, and platelet counts. IL-1β- and TNF-α-induced IL-8 and IL-6 secretion was significantly decreased after the first and second LCAP treatments. These responses were associated with inhibitory effects on nuclear factor (NF)-κB DNA-binding activity.ConclusionsLCAP downregulates the IL-1β- and TNF-α-induced inflammatory responses in PBMCs isolated from UC patients. The induction of hyporesponsiveness to proinflammatory cytokines may be an important factor mediating the clinical effects of LCAP in UC patients.

Intestinal subepithelial myofibroblasts in inflammatory bowel diseases

Colonic subepithelial myofibroblasts (SEMFs) may play a role in the regulation of a number of epithelial cell functions and in the mucosal repair process. In this study, we evaluated the changes in α-smooth muscle actin (SMA)- and vimentin-positive SEMFs in the inflamed mucosa of inflammatory bowel disease (IBD) patients. Tissue samples were surgically obtained from patients with active ulcerative colitis (UC) (n = 5) and active Crohn’s disease (CD) (n = 5). Normal intestinal tissues were also obtained (n = 5). The SMA and vimentin expression was evaluated by standard immunohistochemical procedures. In normal intestinal mucosa, SMA- and vimentin-positive SEMFs were located immediately subjacent to the basement membrane, juxtaposed against the bottom site of the epithelial cells. In the inflamed mucosa of active UC patients, there were relatively more SMA-positive cells compared with normal mucosa. In particular, the increase in SMA-positive cells was greatest at the marginal area of deep ulcers of UC patients. In active CD mucosa, SMA-positive cells were increased in all samples, and a marked increase was observed in two samples. The number of SMA-positive SEMFs was relatively higher in CD mucosa than in UC mucosa. An [3H]thymidine incorporation study demonstrated that platelet-derived growth factor (PDGF)-BB, basic fibroblast growth factor (bFGF), and insulin-like growth factor (IGF)-I significantly increased the uptake of [3H]thymidine into isolated SEMFs. In particular, PDGF had a strong stimulatory effect. We concluded that colonic SEMFs may play an important role in the repair process of IBD.

Fibroblast growth factor-2 stimulates interleukin-6 secretion in human pancreatic periacinar myofibroblasts.

Objectives: Fibroblast growth factor-2 (FGF-2) plays an important role in the pathophysiology of acute and chronic pancreatitis. In the present study, to evaluate the proinflammatory nature of FGF-2, we investigated the effects of FGF-2 on IL-6 secretion in human pancreatic periacinar myofibroblasts. Methods: IL-6 supernatant levels were determined by enzyme-linked immunosorbent assays (ELISA). IL-6 mRNA expression were determined by Northern blots and quantitative PCRs. Activated protein (AP)-1 DNA-binding activities were evaluated by electrophoretic gel mobility shift assays (EMSA). Results: FGF-2 induced IL-6 release in a dose- and time-dependent manner. FGF-2 activity for IL-6 induction was the same as that of IL-17. The combination of FGF-2 and IL-17 exerted additive effects at mRNA and protein levels. FGF-2 induced AP-1 DNA-binding activity, but blockage of AP-1 signaling by adenovirus-mediated transfer of a dominant negative c-Jun gene did not affect FGF-2–induced IL-6 mRNA expression. FGF-2 rapidly induced activation of ERK1/2 and p38 MAP kinases, and specific inhibitors for these enzymes significantly reduced FGF-2-induced IL-6 release. Conclusion: In the pancreas, FGF-2 may not only play a role as a growth factor in tissue injury repair processes but also as an inducer of acute-phase response via stimulation of IL-6 release.