Published papers

Background: The efficacy of calcineurin inhibitors (CNIs) for induction of remission in intestinal Behçet's disease (intestinal BD) has not been explored. Methods: A multicenter retrospective case series study of patients with active intestinal BD treated with CNIs (cyclosporin and tacrolimus) was conducted. Results: Of 16 patients, 12 (75%) showed a clinical response and 5 (31.3%) achieved clinical remission after 2 weeks of CNI treatment. Similar efficacy of CNIs was observed even in 7 patients refractory to antitumor necrosis factor-alpha therapies. Endoscopic improvement was observed in 11 of 12 patients. Conclusions: CNIs may be promising treatment options for refractory intestinal BD.

Background and Aim: Oral therapeutic and invasive endoscopy requires deep sedation to reduce patient distress due to prolonged examination and procedures. The usefulness of capnography and bispectral index (BIS) monitoring in the early hypoxia detection in oral therapeutic and invasive endoscopy has yet to be evaluated. This study aimed to investigate the clinical impact of capnography and BIS monitoring on hypoxic events during oral therapeutic and invasive endoscopic procedures. Methods: This is a prospective observational study. Trans-oral non-intubated therapeutic and/or invasive endoscopic procedures were performed with conventional monitoring (pulse oximetry, pulse, and blood pressure) as well as additional monitoring (BIS and end-tidal CO2 concentration). Hypoxia is defined as oxygen saturation of <90% that lasts >15 s. The clinical impact of capnography and BIS monitoring on hypoxic events during oral therapeutic and invasive endoscopic procedures were investigated with the risk factors for hypoxia in each patient. Results: Patients with hypoxia had significantly more apneas detected using capnography than other patients. The multivariate analysis revealed the detected apnea by capnography as an independent risk factor for hypoxia (odds ratio: 3.48[95% confidence interval: 1.24–9.78], P = 0.02). The BIS was not significantly different as a risk factor for hypoxia; however, per-event analysis revealed significantly decreased BIS values over time in 3 min before hypoxic events. Conclusions: Apnea detected by capnography was an independent predictor of hypoxia. The BIS value was not associated with hypoxia events; however, it showed a significant downward trend before hypoxia events.

Group 2 innate lymphoid cells (ILC2s) serve as frontline defenses against parasites. However, excluding helminth infections, it is poorly understood how ILC2s function in intestinal inflammation, including inflammatory bowel disease. Here, we analyzed the global gene expression of ILC2s in healthy and colitic conditions and revealed that type I interferon (T1IFN)-stimulated genes were up-regulated in ILC2s in dextran sodium sulfate (DSS)-induced colitis. The enhancement of T1IFN signaling in ILC2s in DSS-induced colitis was correlated with the downregulation of cytokine production by ILC2s, such as interleukin-5. Blocking T1IFN signaling during colitis resulted in exaggeration of colitis in both wild-type and Rag2-deficient mice. The exacerbation of colitis induced by neutralization of T1IFN signaling was accompanied by reduction of amphiregulin (AREG) in ILC2s and was partially rescued by exogenous AREG treatment. Collectively, these findings show the potential roles of T1IFN in ILC2s that contribute to colitis manifestation.

Objectives: Peutz–Jeghers syndrome (PJS) is a rare autosomal dominant hereditary disease with a clinical features related to gastrointestinal (GI) hamartomatous polyposis, frequently observed in the small bowel. Balloon-assisted enteroscopy (BAE) has made non-surgical treatment of GI polyps possible. Endoscopic mucosal resection (EMR) has been performed but was associated with complications and difficulties. Recently, endoscopic ischemic polypectomy (EIP) has been developed and its usefulness reported. The study evaluated the feasibility and safety of EIP and the clinical outcomes of patients with PJS. Methods: We retrospectively collected data of consecutive patients with PJS between September 2009 and March 2021. Data regarding clinical characteristics, follow-up methods, endoscopic management, and complications were collected. EIP feasibility and safety were assessed. Results: Twenty-two patients were included. The observation period was 70 months (range, 5–153). Of the 124 therapeutic endoscopy procedures performed, 68 used BAE. Of the 607 polyps treated, 329 polyps were located in the small bowel. EIP was able to treat a greater number of polyps per patient than EMR (P < 0.003), without any complications, carcinoma, or intussusception in the small bowel (P < 0.001). During the follow-up period, 3 patients developed GI cancer. Conclusion: Long-term follow-up in patients with PJS showed that EIP was a feasible and safe technique.

BACKGROUND: Research on whether gastrointestinal symptoms correlate with the severity of Coronavirus Disease 2019 (COVID-19) has been inconclusive. This study aimed to clarify any associations between gastrointestinal symptoms and the prognosis of COVID-19. METHODS: We collected data from the Japanese nationwide registry for COVID-19 to conduct a retrospective cohort study. Data from 3498 Japanese COVID-19 patients, diagnosed at 74 facilities between February 2020 and August 2022, were analyzed in this study. Hospitalized patients were followed up until discharge or transfer to another hospital. Outpatients were observed until the end of treatment. Associations between gastrointestinal symptoms and clinical outcomes were investigated using multivariable-adjusted logistic regression models. RESULTS: The prevalence of diarrhea, nausea/vomiting, abdominal pain, and melena were 16.6% (581/3498), 8.9% (311/3498), 3.5% (121/3498), and 0.7% (23/3498), respectively. In the univariable analysis, admission to intensive care unit (ICU) and requirement for mechanical ventilation were less common in patients with diarrhea than those without (ICU, 15.7% vs. 20.6% (p = 0.006); mechanical ventilation, 7.9% vs. 11.4% (p = 0.013)). In the multivariable-adjusted analysis, diarrhea was associated with lower likelihood of ICU admission (adjusted odds ratio (aOR), 0.70; 95% confidence interval (CI), 0.53-0.92) and mechanical ventilation (aOR, 0.61; 95% CI, 0.42-0.89). Similar results were obtained in a sensitivity analysis with another logistic regression model that adjusted for 14 possible covariates with diarrhea (ICU; aOR, 0.70; 95% CI, 0.53-0.93; mechanical ventilation; aOR 0.62; 95% CI, 0.42-0.92). CONCLUSIONS: Diarrhea was associated with better clinical outcomes in COVID-19 patients.

Organisms use l-amino acids (l-aa) for most physiological processes. Unlike other organisms, bacteria chiral-convert l-aa to d-configurations as essential components of their cell walls and as signaling molecules in their ecosystems. Mammals recognize microbe-associated molecules to initiate immune responses, but roles of bacterial d-amino acids (d-aa) in mammalian immune systems remain largely unknown. Here, we report that amino acid chirality balanced by bacteria-mammal cross-talk modulates intestinal B cell fate and immunoglobulin A (IgA) production. Bacterial d-aa stimulate M1 macrophages and promote survival of intestinal naïve B cells. Mammalian intestinal d-aa catabolism limits the number of B cells and restricts growth of symbiotic bacteria that activate T cell–dependent IgA class switching of the B cells. Loss of d-aa catabolism results in excessive IgA production and dysbiosis with altered IgA coating on bacteria. Thus, chiral conversion of amino acids is linked to bacterial recognition by mammals to control symbiosis with bacteria.

Intestinal intraepithelial lymphocytes (IELs), the first line of defense against microbial and dietary antigens, are classified as natural or induced based on their origin and receptor expression. Induced CD4+CD8αα+TCRβ+ T cells (double positive, DPIELs) originated from CD4+CD8α−TCRβ+ T cells (single positive, SPIELs) increase with aging. However, the metabolic requirements and the metabolic-related genes in IEL development remain unclear. We determined that the intraepithelial compartment is hypoxic in the presence of microbes and DPIELs increased more than natural IELs in this location. Moreover, DPIELs consumed less oxygen and glucose and exhibited unique alterations in mitochondria. Using inhibitors and genetically modified mice, we revealed that DPIELs adapt to their surrounding oxygen-deprived environment in peripheral tissues by modulating specific genes, including hypoxia-inducible factor, mammalian target of rapamycin complexes (mTORC), phosphorylated ribosomal protein S6 (pS6), and other glycolytic factors. Our findings provide valuable insight into the metabolic properties of IELs.

Background: The intestine is rich in food-derived and microbe-derived antigens. Regulatory T cells (Tregs) are an essential T-cell population that prevents systemic autoimmune diseases and inhibits inflammation by encountering antigens. Previously, it was reported that the functional loss of Tregs induces systemic inflammation, including inflammatory bowel disease and graft-versus-host disease in human and murine models. However, there is a dearth of information about how Tregs localize in different tissues and suppress effector cells. Main body: The development of Tregs and their molecular mechanism in the digestive tract have been elucidated earlier using murine genetic models, infectious models, and human samples. Tregs suppress immune and other nonimmune cells through direct effect and cytokine production. The recent development of in vivo imaging technology allows us to visualize how Tregs localize and move in the settings of inflammation and homeostasis. This is important because, according to a recent report, Treg characterization and function are regulated by their location. Tregs located in the proximal intestine and its draining lymph nodes induce tolerance against food antigens, and those located in the distal intestine suppress the inflammation induced by microbial antigens. Taken together, various Tregs are induced in a location-specific manner in the gastrointestinal tract and influence the homeostasis of the gut. Conclusion: In this review, we summarize how Tregs are induced in the digestive tract and the application of in vivo Treg imaging to elucidate immune homeostasis in the digestive tract.

Background and Aim: In patients with Crohn’s disease (CD) and small bowel stenosis, endoscopic balloon dilation (EBD) is considered to be useful in improving stenotic symptoms and avoiding surgery. However, it carries risks such as bleeding and perforation. The aim of this study was to identify the indications for endoscopic intervention in patients with CD and small bowel stenosis. Methods: From November 2007 to March 2020, 143 CD patients with small bowel stenosis were enrolled in this study. We identified the factors associated with not requiring endoscopic intervention during long-term follow-up of these patients. Results: Forty of the 143 patients had abdominal symptoms of stenosis and had undergone EBD, whereas the remaining 103 were asymptomatic and had not undergone endoscopic intervention. During long-term follow-up, 95 of those 103 patients never required endoscopic or surgical intervention. Multivariate logistic regression analysis revealed that not consuming an elemental diet (OR 3.18, 95% CI 1.48–6.82; p <.01) and ileocecal valve (ICV) stenosis (OR 0.30, 95% CI 0.11–0.83; p =.02) were independently associated with not requiring EBD. The cumulative emergency hospitalisation-free rate also tended to be higher in patients not consuming an elemental diet or with ICV stenosis. Conclusions: Two factors, namely not consuming an elemental diet and ICV stenosis, predict a long-term intervention-free prognosis in CD patients with small bowel stenosis.Key messages When an endoscopically impassable small bowel stenosis is found in a CD patient, long-term follow-up without endoscopic intervention may be possible if the patient is asymptomatic, is not using an elemental diet, and the stenosis is ICV.

Objectives: Fever and increased inflammatory responses sometimes occur following endoscopic resection (ER). However, the differences in causes according to the organ are scarcely understood, and several modified ER techniques have been proposed. Therefore, we conducted a comprehensive prospective study to investigate the cause of fever and increased inflammatory response across multiple organs after ER. Methods: We included patients who underwent gastrointestinal endoscopic submucosal dissection (ESD) and duodenal endoscopic mucosal resection at our hospital between January 2020 and April 2022. Primary endpoints were fever and increased C-reactive protein (CRP) levels following ER. The secondary endpoints were risk factors for aspiration pneumonia. Blood tests and radiography were performed on the day after ER, and computed tomography was performed if the cause was unknown. Results: Among the 822 patients included, aspiration pneumonia was the most common cause of fever and increased CRP levels after ER of the upper gastrointestinal tract (esophagus, 53%; stomach, 48%; and duodenum, 71%). Post-ER coagulation syndrome was most common after colorectal ESD (38%). On multivariate logistic regression analysis, lesions located in the esophagus (odds ratio [OR] 3.57; P < 0.001) and an amount of irrigation liquid of ≥1 L (OR 3.71; P = 0.003) were independent risk factors for aspiration pneumonia. Conclusions: Aspiration pneumonia was the most common cause of fever after upper gastrointestinal ER and post-ER coagulation syndrome following colorectal ESD. Lesions in the esophagus and an amount of irrigation liquid of ≥1 L were independent risk factors for aspiration pneumonia.

Recent studies have shown that CD4+CD8αα+ T cells are induced in the hypoxic environment of the small intestinal epithelium. Herein, we describe a protocol for CD4+CD8αα+ T cell induction from freshly isolated naive CD4+ T cells, including procedures for the isolation and enrichment of mouse splenic T cells. In addition, we present an approach that can induce more CD4+CD8αα+ T cells by artificially creating a hypoxic environment in vitro. For complete details on the use and execution of this protocol, please refer to Harada et al. (2022).

Heinrich Schliemann read Homer’s Iliad and believed in the story of Troy. He was a successful businessman in the United States, cornering the market in indigo dye. He first traveled to China and Japan in 1865 after his lucrative career in the dye business. Subsequently, he found the Troy site while visiting sites in Greece, where he established himself as a pioneer in the field of archeology 6 years after traveling through Eastern countries. If he could have read the old literature “Kai Bao Ben Cao” and believed in the importance of the indigo dye for ulcerative colitis (UC), he would have become a pioneer in the field of medicine. Or, in the present, we might be the second Schliemann in the field of UC.

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: Small bowel lesions of Crohn’s disease (CD) are known to be associated with a poor prognosis; however, endoscopic healing leads to favorable patients’ outcome. The aim of this study was to clarify the clinical impact of assessing deep small bowel lesions (DSB) using balloon-assisted enteroscopy (BAE) on CD patients in clinical remission. Methods: From January 2012 to July 2018, a total of 100 CD patients in clinical remission were enrolled to undergo trans-anal enteroscopy using single-balloon enteroscope. Endoscopic evaluations at the terminal ileum (TI) were performed using a partial Simple Endoscopic Score for CD (pSES-CD). Endoscopic evaluations at the DSB used a modified partial SES-CD (mpSES-CD). We evaluated the factors associated with relapse, and the correlation of endoscopic score between the TI and DSB. For this study, relapse was defined as hospitalization within a year from enteroscopy. Results: 30 patients (30.0%) relapsed within a year from enteroscopy. Multivariate logistic regression analysis revealed that the Harvey–Bradshaw Index (OR 1.77, 95% CI 1.18–2.65; p = 0.003) and an mpSES-CD at DSB (OR 3.10, 95% CI 1.86–5.15; p = 0.001) were independent predictors for relapse, whereas a SES-CD at the TI did not exhibit independence. There was a significant correlation trend between the relapse rate and greater than 5 points of an mpSES-CD at DSB; however, there was no correlation between the relapse rate and pSES-CD at the TI. Conclusion: Even when Crohn's disease is in remission, it is important to evaluate DSB using BAE to assess endoscopic mucosal healing.

Cytotoxic CD4+ T cells (CD4-CTLs) show the presence of cytolytic granules, which include the enzymes granzyme and perforin. The cells have a pathogenic and protective role in various diseases, including cancer, viral infection, and autoimmune disease. In mice, cytotoxic CD4+ T cells express CD8αα+ and reside in the intestine (mouse CD4+CTLs; mCD4-CTLs). The population of cytotoxic CD4+ T cells in the human intestine is currently unknown. Moreover, it is unclear how cytotoxic CD4 T cells change in patients with inflammatory bowel disease (IBD). Here, we aimed to identify cytotoxic CD4+ T cells in the human intestine and analyze the characteristics of the population in patients with IBD using single-cell RNA-seq (scRNA-seq). In CD4+ T cells, granzyme and perforin expression was high in humanMAIT (hMAIT) cells and hCD4+CD8A+ T cell cluster. Both CD4 and CD8A were expressed in hTreg, hMAIT, and hCD4+CD8A+ T cell clusters. Next we performed fast gene set enrichment analysis to identify cell populations that showed homology to mCD4CTLs. The analysis identified the hCD4+CD8A+ T cell cluster (hCTL-like population; hCD4-CTL) similar to mouse CTLs. The percentage of CD4+CD8A+ T cells among the total CD4+ T cells in the inflamed intestine of the patients with Crohn’s disease was significantly reduced compared with that in the noninflamed intestine of the patients. In summary, we identified cytotoxic CD4+CD8+ T cells in the small intestine of humans. The integration of the mouse and human sc-RNA-seq data analysis highlight an approach to identify human cell populations related to mouse cell populations, which may help determine the functional properties of several human cell populations in mice.

Mesenteric lymph node (mLN) T cells undergo tissue adaptation upon migrating to intestinal lamina propria and epithelium, ensuring appropriate balance between tolerance and resistance. By combining mouse genetics with single-cell and chromatin analyses, we uncovered the molecular imprinting of gut epithelium on T cells. Transcriptionally, conventional and regulatory (Treg) CD4+ T cells from mLN, lamina propria and intestinal epithelium segregate based on the gut layer they occupy; trajectory analysis suggests a stepwise loss of CD4 programming and acquisition of an intraepithelial profile. Treg cell fate mapping coupled with RNA sequencing and assay for transposase-accessible chromatin followed by sequencing revealed that the Treg cell program shuts down before an intraepithelial program becomes fully accessible at the epithelium. Ablation of CD4-lineage-defining transcription factor ThPOK results in premature acquisition of an intraepithelial lymphocyte profile by mLN Treg cells, partially recapitulating epithelium imprinting. Thus, coordinated replacement of the circulating lymphocyte program with site-specific transcriptional and chromatin changes is necessary for tissue imprinting.

The intricate interplay between gut microbes and the onset of experimental autoimmune encephalomyelitis (EAE) remains poorly understood. Here, we uncover remarkable similarities between CD4+ T cells in the spinal cord and their counterparts in the small intestine. Furthermore, we unveil a synergistic relationship between the microbiota, particularly enriched with the tryptophan metabolism gene EC:1.13.11.11, and intestinal cells. This symbiotic collaboration results in the biosynthesis of kynurenic acid (KYNA), which modulates the recruitment and aggregation of GPR35-positive macrophages. Subsequently, a robust T helper 17 (Th17) immune response is activated, ultimately triggering the onset of EAE. Conversely, modulating the KYNA-mediated GPR35 signaling in Cx3cr1+ macrophages leads to a remarkable amelioration of EAE. These findings shed light on the crucial role of microbial-derived tryptophan metabolites in regulating immune responses within extraintestinal tissues.

Immune checkpoint inhibitors (ICPI) have been reported to be effective in various carcinomas. They excessively activate the immune system, resulting in frequent immune-related adverse events (irAEs). Colitis induced by ICPI is one of the most common and is known as immune-mediated colitis (IMC). Although IMC and inflammatory bowel disease (IBD) are similar in many respects, there are very few reports of IMC in patients with preexisting IBD such as ulcerative colitis (UC) and Crohn's disease (CD). Whether preexisting IBD is concerned with the development of the colitis is not well known. Here, we reported the case who developed severe ulcerative colitis which started from IMC. It is an important case to follow the time course of the colitis developed. Our conclusion indicated that frequent colonoscopy was important for the management of IMC in a patient who has suffered chronic inflammatory disease, such as UC.

Background and aims: Endoscopic remission is known to be defined as a Mayo endoscopic subscore (MES) of ≤1 in patients with ulcerative colitis (UC). However, some individuals experience relapse even after showing endoscopic remission under white-light imaging (WLI), and no tool exists that can detect these individuals. The aim of this study was to clarify the usefulness of texture and color enhancement imaging (TXI) in the assessment of inflammation in patients with UC. Methods: This was a prospective, single-arm, observational study conducted at a university hospital. From January 2021 to December 2021, 146 UC patients with endoscopic remission were enrolled. Images were evaluated by WLI, TXI, and pathologic evaluation, followed by prognostic studies. The primary endpoint of the study was the cumulative relapse of UC in each TXI score. The secondary endpoints were the association between TXI and pathologic scores, predictors of relapse, and interobserver agreement between the MES and TXI scores. Results: Patients with TXI score 2 had significantly lower UC relapse-free rates than did those with TXI scores 0-1 (log-rank test, P < .01). When pathologic remission was defined as Matts grade ≤2, the rate of pathologic remission decreased significantly with higher TXI scores (P = .01). In multivariate analysis, TXI score 2 was the only risk factor for UC relapse (P < .01; hazard ratio, 4.16; 95% confidence interval, 1.72-10.04). Interobserver agreement on the TXI score was good (κ = 0.597-0.823). Conclusion: TXI can be used to identify populations with poor prognosis in MES 1, for whom treatment intensification has been controversial.