Inflammatory bowel disease (IBD) is a chronic disorder involving mainly the intestinal tract, but possibly other gastrointestinal and extraintestinal organs. Although etiology is still uncertain, recent knowledge in pathogenesis has accumulated, and novel diagnostic and therapeutic modalities have become available for clinical use. Therefore, the previous guidelines were urged to be updated. In 2016, the Japanese Society of Gastroenterology revised the previous versions of evidence-based clinical practice guidelines for ulcerative colitis (UC) and Crohn’s disease (CD) in Japanese. A total of 59 clinical questions for 9 categories (1. clinical features of IBD; 2. diagnosis; 3. general consideration in treatment; 4. therapeutic interventions for IBD; 5. treatment of UC; 6. treatment of CD; 7. extraintestinal complications; 8. cancer surveillance; 9. IBD in special situation) were selected, and a literature search was performed for the clinical questions with use of the MEDLINE, Cochrane, and Igaku Chuo Zasshi databases. The guidelines were developed with the basic concept of the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system. Recommendations were made using Delphi rounds. This English version was produced and edited based on the existing updated guidelines in Japanese.

Inflammatory bowel disease (IBD) is a general term for chronic or remitting/relapsing inflammatory diseases of the intestinal tract and generally refers to ulcerative colitis (UC) and Crohn’s disease (CD). Since 1950, the number of patients with IBD in Japan has been increasing. The etiology of IBD remains unclear; however, recent research data indicate that the pathophysiology of IBD involves abnormalities in disease susceptibility genes, environmental factors and intestinal bacteria. The elucidation of the mechanism of IBD has facilitated therapeutic development. UC and CD display heterogeneity in inflammatory and symptomatic burden between patients and within individuals over time. Optimal management depends on the understanding and tailoring of evidence-based interventions by physicians. In 2020, seventeen IBD experts of the Japanese Society of Gastroenterology revised the previous guidelines for IBD management published in 2016. This English version was produced and modified based on the existing updated guidelines in Japanese. The Clinical Questions (CQs) of the previous guidelines were completely revised and categorized as follows: Background Questions (BQs), CQs, and Future Research Questions (FRQs). The guideline was composed of a total of 69 questions: 39 BQs, 15 CQs, and 15 FRQs. The overall quality of the evidence for each CQ was determined by assessing it with reference to the Grading of Recommendations Assessment, Development and Evaluation approach, and the strength of the recommendation was determined by the Delphi consensus process. Comprehensive up-to-date guidance for on-site physicians is provided regarding indications for proceeding with the diagnosis and treatment.

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There is an expansion of FOXP3+CD4+ T cells in mucosal lymphoid tissues in UC. CD4+CD25+ isolated from UC MLN express FOXP3 and display features of TR cells in spite of active mucosal inflammation. These data suggest that their suppressor activity may be abrogated in vivo or they are unable to counterbalance the chronic mucosal inflammation in UC.

Ulcerative colitis (UC) is characterized by a long-standing chronic inflammation of the bowel with intermittent periods of exacerbation and remission. Its acute exacerbation appears to be related to various stresses. Urocortin 1 (Ucn1) may play important roles in integrated local responses to stress. We therefore examined local production of Ucn1 in patients with UC by immunohistochemistry and mRNA in situ hybridization. Ucn1 immunoreactivity was predominantly detected in lamina propria plasma cells and enterochromaffin cells. In UC patients without glucocorticoid treatment, Ucn1-positive cells and plasma cells increased in proportion to the severity of inflammation (P < 0.0001). Ucn1-positive cells significantly increased in UC patients with advanced inflammatory grades, compared with a control group (P < 0.0001) and nonspecific colitis group (P < 0.0001). In glucocorticoid-treated patients, Ucn1-positive cells were significantly lower in number, compared with the nonglucocorticoid-treated group. Ucn1 mRNA was expressed in lamina propria plasma cells, and both corticotropin-releasing factor(1) and corticotropin-releasing factor(2(a)) mRNAs were also partially coexpressed in these cells and macrophages. The present study showed that Ucn1-positive cells were correlated with the severity of inflammation in colonic mucosa with UC, and glucocorticoid treatment decreased these cells. Ucn1 therefore may act as a possible local immune-inflammatory mediator in UC.

CCL25/CCR9 chemokine ligand/receptor pair has been reported to play an important role in small bowel (SB) immunity and inflammation. We have previously reported an aberrant SB expression of CCL25 in Crohn’s disease (CD) and an increased frequency of CCR9+ T cells in the peripheral blood of patients with SB inflammatory diseases such as CD and celiac disease. In this study, we have characterized the phenotype and effector function of CCR9+ T cells in mucosal lymphoid tissues in CD. We show that CCR9+ T cells isolated from mesenteric lymph nodes (MLN) draining CD SB express a more activated phenotype compared with MLN draining normal SB. Stimulation of CCR9+ T cells isolated from CD SB lamina propria produced more IFN-γ and IL-17 in response to anti-CD3 or IL-12/IL-18 stimulation compared with those isolated from normal SB. The addition of TL1A to the cytokine combination markedly augmented the secretion of IFN-γ, but not IL-17, by CD lamina propria CCR9+ T cells. CCL25 incubation of CD SB lamina propria lymphocytes and MLN lymphocytes increased their adhesion to VCAM-1/Fc in vitro. Finally, the TCRVβ analysis of CCR9+ T cells revealed a diverse TCRVβ repertoire among MLN CCR9+ T cells in patients with SB CD. Our data indicate that CCR9+ T cells in SB CD are proinflammatory and support the rationale for the use of CCR9 antagonists for the treatment of human SB CD.

Background We evaluated whether oral vitamin D supplementation during the winter and early spring reduces the incidence of influenza and upper respiratory infections in patients with inflammatory bowel disease (IBD). Methods A randomized, double-blind, controlled trial was conducted to compare the effects of vitamin D supplementation (500 IU/day) and a placebo. The primary outcome was the incidence of influenza; the secondary outcome was the incidence of upper respiratory infection. Prespecified subgroup analyses were performed according to 25-hydroxyvitamin D (25-OHD) levels (low <20 ng/mL or high ≥20 ng/mL) and whether ulcerative colitis (UC) or Crohn’s disease (CD) was present. We also used the Lichtiger clinical activity index for patients with UC and the Crohn’s Disease Activity Index (CDAI) for patients with CD before and after interventions. Results We included 223 patients with IBD and randomized them into 2 groups: vitamin D supplementation (n = 108) and placebo (n = 115). The incidence of influenza did not differ between the groups. However, the incidence of upper respiratory infection was significantly lower in the vitamin D group (relative risk [RR], 0.59; 95% confidence interval (CI), 0.35–0.98; P = 0.042). This effect was enhanced in the low 25-OHD level subgroup (RR, 0.36; 95% CI, 0.14–0.90; P = 0.02). With respect to adverse events, the Lichtiger clinical activity index score was significantly worse in the vitamin D group ( P = 0.002) and remained significant only in the high 25-OHD level subgroup. Conclusions Vitamin D supplementation may have a preventative effect against upper respiratory infection in patients with IBD but may worsen the symptoms of UC.

Urocortin III (Ucn III)/stresscopin (SCP) is a novel peptide of the corticotropin-releasing factor (CRF) family and is a specific ligand for the CRF type 2 receptor. We wished to clarify whether Ucn III/SCP is expressed in the human heart and kidney. Immunoreactive Ucn III was detected by RIA in the human heart (0.74-1.15 pmol/g wet weight, mean +/- SEM; n = 4) and kidney (1.21 +/- 0.30 pmol/g wet weight), which were obtained at autopsy. These levels were comparable to the levels in pituitary (2.72 +/- 0.13 pmol/g wet weight; n = 3) and brain tissues ( approximately 1-2 pmol/g wet weight). Furthermore, immunoreactive Ucn III was present in human plasma (51.8 +/- 16.0 pmol/liter; n = 5) and urine (266 +/- 20 pmol/liter; n = 5) obtained from healthy subjects. Reverse-phase HPLC showed a broad peak of immunoreactive Ucn III eluting in the position of synthetic Ucn III in the heart, kidney, and hypothalamus. Material eluting in the position of SCP was also found in the HPLC analysis of these tissue extracts. Immunocytochemistry showed positive staining of Ucn III in the myocardium and the renal tubules, particularly distal tubules. RT-PCR showed expression of Ucn III mRNA in the brain, pituitary, heart, and kidney. The present study has shown expression of Ucn III/SCP in the human heart and kidney as well as brain and pituitary tissues and its presence in plasma and urine. Ucn III/SCP may therefore regulate the cardiac and renal function as a local factor and a circulating hormone.