Kosuke Takaki

Germinated barley foodstuff, a prebiotic product, ameliorates inflammation of colitis through modulation of the enteric environment

Background: Germinated barley foodstuff (GBF), which contains glutamine-rich protein and hemicellulose-rich fiber, exhibits therapeutic effects in ulcerative colitis; however, its mechanism is still under investigation. The aim of this study was to evaluate the anti-inflammatory effects of GBF on colitis in terms of the epithelial inflammatory response. Methods: Mice with dextran sulfate sodium-induced colitis were used. The effects of GBF on the colitis were evaluated by measuring the body weight; disease activity; mucosal damage (histology, mucosal inflammatory parameters, nuclear factor kappa B [NFkB] activation, and signal transducer and activator of transcription 3 [STAT3]); serum interleukin 6 (IL-6) level; cecal short-chain fatty acids (SCFAs); and bile acid contents. Results: GBF significantly prevented disease activity and body weight loss after induction of colitis. Serum IL-6 level and mucosal STAT3 expression were also significantly attenuated, with a conspicuous reduction of mucosal damage; NFkB activity showed the same tendency. Cecal butyrate content was significantly higher and, interestingly, GBF mice had lower bile acid concentrations than the control group. Conclusions: GBF has the potential to reduce the epithelial inflammatory response by depressing STAT-3 expression and inhibiting NFkB binding activity. These effects may be brought about by an increase of butyrate production and adsorption of bile acids.

Interleukin-10 in the Pathophysiology of Inflammatory Bowel Disease: Increased Serum Concentrations During the Recovery Phase

Using a specific enzyme-linked immunosorbent assay, IL-10 concentrations were measured in serum from 62 patients with ulcerative colitis (UC), 43 with Crohns disease (CD), 25 with other colitides, and 44 normal control subjects. Serum IL-10 concentrations were increased in patients with active UC but not in those with active CD when compared with normal control subjects. A time course study showed that in patients with UC and CD, serum concentrations of IL-6 and C-reactive protein increased during the acute phase and returned to normal as patients go into remission. Notably, serum IL-10 concentrations increased during the phase of disease resolution and declined thereafter regardless of the treatment modality. Gel filtration analysis indicated that IL-10 circulated predominantly as a dimer. In conclusion, this study shows that serum IL-10 is increased during disease recovery in patients with inflammatory bowel disease, and may be a helpful marker in monitoring disease status.

Diminished cytokine signalling against bacterial components in mononuclear leucocytes from ulcerative colitis patients after leukocytapheresis

Infiltration by circulating inflammatory cells is a prominent local inflammatory feature of ulcerative colitis (UC). Several trials have suggested that leukocytapheresis by filtration can benefit patients with active UC. We investigated how this therapy might modulate the inflammatory response. Patients with active UC who were beginning repeated filtration leukocytapheresis were studied. Mononuclear cell preparations were obtained from blood before and after the first treatment, and expression of cytokine signalling components and the cell‐proliferative response were analysed in vitro. Leukocytapheresis reduced lipopolysaccharide‐induced production of proinflammatory cytokines (interleukin‐1, ‐6, ‐8 and tumour necrosis factor‐α, P < 0·05 for all) and activation of intracellular signalling components (nuclear factor‐κB, mitogen‐activated protein kinases, and signal transducer and activator of transcription‐3), as well as surface expression of toll‐like receptor‐4 (P < 0·05) in mononuclear cells. The therapy also reduced the cell‐proliferative response by mononuclear cells stimulated with sonicated bacterial preparations from autologous intestine (P < 0·05). These results indicate that activated mononuclear cells in the peripheral blood of patients with active UC are removed by leukocytapheresis and replaced by cells with a lower activation status. This replacement may partly explain the therapeutic benefit.

Increased Circulating Concentrations of Growth-Related Oncogene (GRO)-α in Patients with Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic inflammatory state associated with increased risk of intestinal cancers. The aim of this study is to examine serum concentrations of growth-related oncogene (GRO)-α, a cytokine with inflammatory and growth-regulatory properties, in patients with IBD. We measured serum concentrations of GRO-α in 60 patients with ulcerative colitis, 42 patients with Crohns disease, 16 patients with other colitides, 12 patients with colorectal cancer, and 40 normal subjects using an enzyme-linked immunosorbent assay. We then analyzed how the cytokine was related to clinical and laboratory variables. Serum GRO-α concentrations in patients with active IBD were significantly higher than those in patients with quiescent disease, which in turn were higher than those in normal controls. Concentrations in patients with active ulcerative colitis were higher than in patients with active Crohns disease. Analysis of paired serum samples showed a decrease in GRO-α after initiation of therapy. Furthermore, serum GRO-α correlated well with laboratory markers of IBD activity. We conclude that GRO-α may have an important role in development of IBD, and might itself be used as a marker of activity. Manipulation of GRO-α function might prove therapeutically useful.

A form of circulating interleukin-6 receptor component soluble gp130 as a potential interleukin-6 inhibitor in inflammatory bowel disease

The presence and the role of soluble gp130, the soluble form of a component of the interleukin (IL)‐6 receptor complex, were investigated in inflammatory bowel disease. The serum concentrations of soluble gp130 were increased in ulcerative colitis (active disease, median, 93·5 ng/ml; interquartile range, 26–125 ng/ml; inactive disease, 81 ng/ml, 24·8–137·3 ng/ml) and to a lesser extent in Crohns disease (active disease, 66 ng/ml, 44·4–87·6 ng/ml; inactive disease, 63 ng/ml, 43·5–82·5 ng/ml) compared to normal controls (43 ng/ml, 27–59 ng/ml). Paired analysis of serum samples showed a decrease of IL‐6 and soluble IL‐6 receptor concentrations in both diseases and an increase of soluble gp130 concentrations, especially in ulcerative colitis, just after the resolution of disease exacerbation. Size fractionation of the serum revealed that a part of the IL‐6 co‐eluted with soluble gp130 and soluble IL‐6 receptor. The IL‐6‐induced proliferation of murine B9 hybridoma was enhanced by recombinant soluble IL‐6 receptor, whereas the proliferation was inhibited by recombinant soluble gp130. These results indicate that soluble gp130 may function as a natural inhibitor of the IL‐6 actions in inflammatory bowel disease.

Attenuation of experimental colonic injury by thiazolidinedione agents

Abstract.Objective: We investigated the potential use and action mechanisms of thiazolidinedione (TZD) agonists for peroxisome proliferator-activated receptor-γ, namely pioglitazone and netoglitazone, during dextran sulfate sodium (DSS)-induced colitis in mice. Methods: Colitis was induced by the drinking of 2.5% DSS for 7 days. In the prophylactic protocol, pioglitazone or netoglitazone was administered 2 days before the first DSS exposure and repeated daily for a total of 10 doses. In the therapeutic protocol, pioglitazone was administered 2 days after the first DSS exposure and repeated daily for a total of 10 doses. The effect of pioglitazone on proinflammatory cytokine signaling was examined both in vivo and in vitro. Results: Colitis was significantly attenuated by both pioglitazone and netoglitazone in the prophylactic protocol and by pioglitazone in the therapeutic protocol. The improvement of colitis by pioglitazone was associated with decreased colonic interleukin-6, and phospho-signal transducer and activator of transcription-3 levels. In vitro experiments revealed that culturing lamina propria mononuclear cells in the presence of pioglitazone down-regulated the production of interleukin-6. Conclusions: These TZD agents should be considered for use as new therapeutic agents in intestinal inflammation such as inflammatory bowel disease. TZD-induced improvement in inflammation is explained, in part, by down-regulation of proinflammatory cytokine signaling.

Activation of c-Jun N-terminal kinase (JNK) signalling in experimentally induced gastric lesions in rats

The c‐Jun N‐terminal kinase (JNK) participates in intracellular signalling cascades that mediate inflammatory responses. Therefore, the JNK signalling may be involved in gastric injury and inhibition of this pathway may form the basis of a new strategy for the treatment of gastric injury. The aim of this study was to determine whether JNK participates in the formation of gastric lesions in an experimental model. Acute gastric injury was induced in Sprague‐Dawley rats by intragastric administration of 100% ethanol. The amount of phospho‐JNK in the rat stomach was determined using immunohistochemistry and Western analysis. Animals received subcutaneous injections of a specific JNK inhibitor SP600125 or vehicle and the extent of mucosal damage in the stomach was determined. Western analysis revealed early phosphorylation of JNK and, to a lesser extent, p38 as well as late phosphorylation of the p42/44 extracellular signal‐related kinases during the development of gastric lesions. JNK was phosphorylated in epithelial cells and in occasional mononuclear cells present at lesion sites. These cells were rarely found in samples from control specimens. Treatment with SP600125 significantly reduced the extent of gastric lesions. These findings indicate that experimental gastric injury is associated with activation of the JNK signalling pathway, and also suggest that JNK inhibitors may play a role in the treatment of gastric injury in humans.

Transcription Factor-Targeted Therapies in Inflammatory Bowel Disease

Although the causes of inflammatory bowel disease currently are not fully understood, increasing evidence implicates cytokines as key factors in the development of this disorder. The rationale for cytokine-targeted therapy for inflammatory bowel disease has been refined significantly, and clinical studies have been initiated. Recent investigations have focused on transcription factors that regulate production and activation of cytokines, including the nuclear factor-ĸB, the p38 mitogen-activated protein kinase, the peroxisome proliferator-activated receptor-γ, and the Janus kinases/signal transducers and activator of transcription pathways. Although their exact role in inflammatory bowel disease is still unknown, further studies may lead to identification of additional possible targets for therapeutic intervention that could improve management of the disease.