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.

Background The mucosa-associated gut microbiota directly modulates epithelial and mucosal function. In this study, we investigated the mucosa-associated microbial community in patients with inflammatory bowel disease (IBD), using endoscopic brush samples. Methods A total of 174 mucus samples from 43 patients with ulcerative colitis (UC), 26 with Crohn’s disease (CD) and 14 non-IBD controls were obtained by gentle brushing of mucosal surfaces using endoscopic cytology brushes. The gut microbiome was analyzed using 16S rRNA gene sequencing. Results There were no significant differences in microbial structure among different anatomical sites (the ileum, cecum and sigmoid colon) within individuals. There was, however, a significant difference in microbial structure between CD, UC and non-IBD controls. The difference between CD and non-IBD controls was more marked than that between UC patients and non-IBD controls. α-Diversity was significantly lower in UC and CD patients than non-IBD controls. When comparing CD patients with non-IBD controls, the phylum Proteobacteria was significantly increased and the phyla Firmicutes and Bacteroidetes were significantly reduced. These included a significant increase in the genera Escherichia, Ruminococcus (R. gnavus), Cetobacterium, Actinobacillus and Enterococcus, and a significant decrease in the genera Faecalibacterium, Coprococcus, Prevotella and Roseburia. Comparisons between CD and UC patients revealed a greater abundance of the genera Escherichia, Ruminococcus (R. gnavus), Clostridium, Cetobacterium, Peptostreptococcus in CD patients, and the genera Faecalibacterium, Blautia, Bifidobacterium, Roseburia and Citrobacter in UC patients. Conclusions Mucosa-associated dysbiosis was identified in IBD patients. CD and UC may be distinguishable from the mucosa-associated microbial community structure.

Inflammation is an essential component of the immune response that protects the host against pathogens and facilitates tissue repair. Chronic inflammation is a critical factor in cancer development and progression. It affects every stage of tumor development, from initiation and promotion to invasion and metastasis. Tumors often create an inflammatory microenvironment that induces angiogenesis, immune suppression, and malignant growth. Immune cells within the tumor microenvironment interact actively with cancer cells, which drives progression through complex molecular mechanisms. Chronic inflammation is triggered by factors such as infections, obesity, and environmental toxins and is strongly linked to increased cancer risk. However, acute inflammatory responses can sometimes boost antitumor immunity; thus, inflammation presents both challenges and opportunities for therapeutic intervention. This review examines how inflammation contributes to tumor biology, emphasizing its dual role as a critical factor in tumorigenesis and as a potential therapeutic target.

Altered gut microbial ecology contributes to the development of metabolic diseases including obesity. In this study, we performed 16S rRNA sequence analysis of the gut microbiota profiles of obese and lean Japanese populations. The V3–V4 hypervariable regions of 16S rRNA of fecal samples from 10 obese and 10 lean volunteers were sequenced using the Illumina MiSeqTMII system. The average body mass index of the obese and lean group were 38.1 and 16.6 kg/m2, respectively (p<0.01). The Shannon diversity index was significantly higher in the lean group than in the obese group (p<0.01). The phyla Firmicutes and Fusobacteria were significantly more abundant in obese people than in lean people. The abundance of the phylum Bacteroidetes and the Bacteroidetes/Firmicutes ratio were not different between the obese and lean groups. The genera Alistipes, Anaerococcus, Corpococcus, Fusobacterium and Parvimonas increased significantly in obese people, and the genera Bacteroides, Desulfovibrio, Faecalibacterium, Lachnoanaerobaculum and Olsenella increased significantly in lean people. Bacteria species possessing anti-inflammatory properties, such as Faecalibacterium prausnitzii, increased significantly in lean people, but bacteria species possessing pro-inflammatory properties increased in obese people. Obesity-associated gut microbiota in the Japanese population was different from that in Western people.