Crohn's disease and ulcerative colitis represent two distinct forms of inflammatory bowel diseases (IBD). In this paper, we discuss how immunological mechanisms contribute to the pathogenesis of IBD. Intestinal homeostasis is sustained by various kinds of cells, such as epithelial cells, lymphocytes, antigen presenting cells, and other innate immune cells. We pay special attention to intestinal CD14+ macrophages. Intestinal macrophages play a central role in the regulation of immune responses against commensal bacteria. In the physiological condition, intestinal macrophages lack the expression of innate-immune receptor CD14 and do not produce proinflammatory cytokines. We identified a unique macrophage subset of IBD in the human intestine, which expressed both macrophage (CD14, CD33, CD68) and dendritic cell (DC) markers (CD205, CD209) and produced larger amounts of proinflammatory cytokines, such as interleukin (IL)-23 and tumor necrosis factor (TNF)-alpha. In addition, the CD14+ macrophages contributed to interferon (IFN)-gamma production rather than IL-17 production by lamina propria mononuclear cells dependent on IL-23. We discuss herein this IL-23/IFN-gamma-positive feedback loop in IBD patients. We also discuss IFN-gamma and IL-17 production from mucosal T cells and natural killer (NK) cells. Here, we show our recent findings about the plasticity of T helper cells in colitis. Th 17 cells express T-bet, and finally lose the expression of retinoic acid-related orphan receptor (ROR)gammat, the master regulator of Th 17 cells, and are differentiated 'alternative Th 1 cells.' In addition to Th 1 cells, mucosal NK cells are also important sources of IFN-gamma. Some of our ideas may be provocative, but we hope this review paper will provide new and firm understanding of the pathogenesis of IBD.
Antigen-Presenting Cells ; Bacteria ; Child ; Child, Orphaned ; Colitis ; Colitis, Ulcerative ; Crohn Disease ; Cytokines ; Dendritic Cells ; Epithelial Cells ; Homeostasis ; Humans ; Inflammatory Bowel Diseases ; Interferons ; Interleukin-17 ; Interleukin-23 ; Interleukins ; Intestines ; Killer Cells, Natural ; Lymphocytes ; Macrophages ; Mucous Membrane ; Plastics ; T-Lymphocytes ; T-Lymphocytes, Helper-Inducer ; Tumor Necrosis Factor-alpha

Background/Aims: Thromboprophylaxis is recommended for hospitalized patients with inflammatory bowel disease (IBD) in Western countries, although it is selectively administered to high-risk patients in East Asia. A central venous catheter (CVC) is commonly placed in patients with IBD. Although CVC placement is considered a risk factor for venous thromboembolism (VTE), the degree of increased risk in patients with IBD is uncertain. This study aimed to identify the risk of VTE with CVC placement in hospitalized Japanese patients with IBD without thromboprophylaxis. Methods: This retrospective cohort study included patients with ulcerative colitis or Crohn’s disease who were admitted for disease flares at Keio University Hospital between January 2016 and December 2020. Patients who already had thrombosis or were administered any antithrombotic treatment on admission were excluded. VTE development during the hospitalization was surveyed, and VTE risk associated with CVC indwelling was estimated using propensity score matching and inverse probability of treatment weighting analyses. Results: Altogether, 497 hospitalized patients with IBD (ulcerative colitis, 327; Crohn’s disease, 170) were enrolled. VTE developed in 9.30% (12/129) of catheterized patients and in 0.82% (3/368) of non-catheterized patients. The propensity score matching yielded 127 matched pairs of patients. The catheterized group demonstrated higher odds for VTE than the non-catheterized group (odds ratio, 13.15; 95% confidence interval, 1.68–102.70). A similar result was obtained in the inverse probability of treatment weighting analysis (odds ratio, 11.02; 95% confidence interval, 2.64–46.10). Conclusions CVC placement is a major risk factor for VTE among hospitalized Japanese patients with IBD without thromboprophylaxis.

BACKGROUND: Mandibular reconstruction is performed after segmental mandibulectomy, and precise repositioning of the condylar head in the temporomandibular fossa is essential for maintaining preoperative occlusion. METHODS: In cases without involvement of soft tissue around the mandibular bone, the autopolymer resin in a soft state is pressed against the lower border of the mandible and buccal and lingual sides of the 3D model on the excised side. After hardening, it is shaved with a carbide bar to make the proximal and distal parts parallel to the resected surface in order to determine the direction of mandibular resection. On the other hand, in cases that require resection of soft tissue around the mandible such as cases of a malignant tumor, right and left mandibular rami of the 3D model are connected with the autopolymer resin to keep the preoperative position between proximal and distal segments before surgical simulation. The device is made to fit the lower border of the anterior mandible and the posterior border of the mandibular ramus. The device has a U-shaped handle so that adaptation of the device will not interfere with the soft tissue to be removed and has holes to be fixed on the mandible with screws. RESULTS: We successfully performed the planned accurate segmental mandibulectomy and the precise repositioning of the condylar head by the device. CONCLUSIONS: The present technique and device that we developed proved to be simple and useful for restoring the preoperative condylar head positioning in the temporomandibular fossa and the precise resection of the mandible.
Hand ; Head ; Mandible* ; Mandibular Osteotomy* ; Mandibular Reconstruction

Background/Aims: The evaluation of small bowel lesions of Crohn’s disease (CD) using balloon-assisted enteroscopy (BAE) is crucial because mucosal healing is associated with a good prognosis. However, BAE procedures are invasive, requiring sedation or analgesia to reduce the patient’s pain.This study evaluated the clinical usefulness of a novel ul-trathin single-balloon enteroscopy (SBE) procedure for CD. Methods: This single-center retrospective study included 102 CD patients who underwent trans-anal SBE between Janu-ary 2012 and May 2018. Of these patients, 82 underwent enteroscopy using conventional SBE, while 20 underwent ultrathin SBE. Patients were analyzed using propensity score matching, with 20 patients per group. The median duration of the examination, terminal ileum intubation rate, median cecum intubation time, median insertion depth, adverse events, and sedated dose in each group were compared. Results: Before propensity score matching, the conventional SBE group had a larger number of surgical history patients than the ultrathin SBE group (p=0.05). After matching, the two groups did not significantly differ clinically. There were no significant differences in the mean duration of the examina-tion, cecum intubation time, or terminal ileal intubation rate between ultrathin SBE and conventional SBE. The mean in-sertion depth of ultrathin SBE tended to be deeper than that of conventional SBE (p=0.09). The use of ultrathin SBE also reduced the sedative dose during needed for enteroscopy compared with conventional SBE (p=0.005). Conclusions Novel ultrathin SBE may be less painful for CD patients than conventional SBE.

Background/Aims: 5-Aminosalicylic acid (ASA) causes intolerance reactions in some patients. This study was performed to examine the prognosis of patients with ulcerative colitis (UC) and 5-ASA intolerance, and to evaluate the potential interaction between 5-ASA intolerance and the intestinal microbiota. Methods: We performed a retrospective cohort study of patients with UC who visited participating hospitals. The primary endpoint was to compare the incidence of hospitalization within 12 months between the 5-ASA intolerance group and the 5-ASA tolerance group. The secondary endpoint was to compare the risk of adverse clinical outcomes after the start of biologics between the 2 groups. We also assessed the correlation between 5-ASA intolerance and microbial change in an independently recruited cohort of patients with UC. Results: Of 793 patients, 59 (7.4%) were assigned to the 5-ASA intolerance group and 734 (92.5%) were assigned to the 5-ASA tolerance group. The admission rate and incidence of corticosteroid use were significantly higher in the intolerance than tolerance group (P< 0.001). In 108 patients undergoing treatment with anti-tumor necrosis factor biologics, 5-ASA intolerance increased the incidence of additional induction therapy after starting biologics (P< 0.001). The 5-ASA intolerance group had a greater abundance of bacteria in the genera Faecalibacterium, Streptococcus, and Clostridium than the 5-ASA tolerance group (P< 0.05). Conclusions In patients with UC, 5-ASA intolerance is associated with a risk of adverse clinical outcomes and dysbiosis. Bacterial therapeutic optimization of 5-ASA administration may be important for improving the prognosis of patients with UC.