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Background: Pouchitis is an inflammatory condition that affects the ileal pouch during ileal pouch-anal anastomosis surgery. Despite its clinical significance, precise immunological mechanisms underlying pouchitis remain unclear. This study aimed to investigate the lymphocyte profile in the ileal pouch of patients with pouchitis compared to those with familial adenomatous polyposis (FAP) and ulcerative colitis without pouchitis using flow cytometry and immunohistochemical techniques., Methods: We prospectively analyzed endoscopic biopsy specimens from the ileal pouches of 15 patients and categorized them into three groups: FAP, ulcerative colitis with an inflammation-free pouch (UC-I), and ulcerative colitis with ulcers and/or erosions in the pouch (UC-UE). Flow cytometry was used to assess various T-lymphocyte markers, including cluster of differentiation (CD) 4, CD8, CD56, and human leukocyte antigen (HLA)-DR. Immunohistochemistry was performed to visualize the spatial distribution of CD3+, CD56+, and HLA-DR+ cells in the pouch mucosa., Results: We observed significantly reduced CD56+/CD3+ and CD8+/CD3+ ratios in the UC-UE group compared to those in the FAP group, indicating a disruption in natural killer T-cell populations. Immunohistochemical analysis revealed that the spatial distribution of lymphocytes differed among the non-inflamed mucosa, dense lymphocyte infiltration, and lymphoid follicles, with these components frequently intermingling. CD56 + cells were less abundant in areas with dense lymphocyte infiltration, whereas HLA-DR+ cells were more abundant., Conclusion: Our study revealed a decrease in CD56+ natural killer T cells and an increase in HLA-DR+-activated T cells in areas with dense lymphocyte infiltration, suggesting an association between these cells and pouchitis in ulcerative colitis. The distinct patterns observed in non-inflamed mucosa, areas with dense lymphocyte infiltration, and lymphoid follicles underscore the need for further analyses of these three segments to elucidate the immunological mechanisms underlying pouchitis., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Ethics Committee of Okayama University Hospital, Okayama, Japan issued approval 2203-039. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: This study was partially supported by JSPS KAKENHI (grant number: JP22K07962). Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Iwamuro et al.)

We present the case of a patient who underwent human leukocyte antigen-haploidentical transplantation for T-cell acute lymphoblastic leukemia. Seven weeks after transplantation, the patient developed intestinal transplant-associated microangiopathy (iTAM). Although the iTAM was resolved temporarily, it recurred. Video capsule enteroscopy revealed multiple erosions and shallow ulcers in the jejunum and ileum. To the best of our knowledge, this is the first report to present images of possible small intestinal lesions in iTAM. The small intestinal mucosal images presented herein may potentially aid in the management of similar patients., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: Funding: This work was partially supported by JSPS KAKENHI (grant number: JP22K07962). Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Kametaka et al.)

Herein, we outlined two case reports of patients who developed cytomegalovirus colitis following the initiation of corticosteroid therapy for colitis as a result of immune-related adverse events (irAEs). For both patients, endoscopic findings were similar to those observed for patients with irAE colitis but were devoid of the characteristic features associated with cytomegalovirus colitis, including punched-out ulcers. Given the therapeutic disparities between these two conditions, it is imperative to distinguish between these conditions in clinical practice. When addressing exacerbations or refractory manifestations of irAE-associated colitis, clinicians should remain vigilant with regard to the potential for cytomegalovirus infection, even in the absence of punched-out ulcers in the colorectum., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: Funding This work was partially supported by JSPS KAKENHI (grant number: JP22K07962)., (Copyright © 2024, Iwamuro et al.)

The composition of lymphocytes in the gastric mucosa following the eradication of Helicobacter pylori ( H. pylori ) in patients with and without gastric cancer has not been compared. This study performed a single spot analysis of gastric mucosal lymphocytes after H. pylori eradication in patients with (n = 13) and without (n = 20) gastric cancer. Our comprehensive analysis of lymphocyte composition in the gastric mucosa revealed that: i) the proportion of CD8 + /CD3 + cells was relatively higher in the peri-tumor mucosa than in the background mucosa; ii) the proportion of CCR4 + /CD3 + cells was higher, and the ratio of CD62L + /CD3 + CD4 + cells was relatively lower in the gastric mucosa of cancer patients than in non-cancer patients; and iii) the proportion of CD45RA - CD62L + /CD3 + CD4 + cells, namely, the central memory CD4 + T-cell fraction, was lower in the gastric mucosa of cancer patients than in non-cancer patients. Although the exact mechanism of the altered proportions of CCR4 + /CD3 + and central memory CD4 + cells in the gastric mucosa of patients with cancer is unknown, focusing on lymphocytes in the gastric mucosa might help improve our understanding of gastric cancer development after H. pylori eradication., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2022, Iwamuro et al.)

Diagnostic utility of fluorescence microscopy for lanthanum phosphate deposition in the gastrointestinal mucosa has not been reported previously. In this study, we comparatively assessed the light, electron, and fluorescence microscopy features of gastroduodenal lanthanum phosphate deposition in 10 patients with deposits in the stomach and 5 patients with deposits in the duodenum. During light microscopy, lanthanum deposits were observed as dark-brown, needle-shaped, or crystalloid structures and pale red amorphous materials. During electron microscopy, the deposited material appeared as bright aggregates. Fluorescence microscopy also revealed lanthanum deposits as bright areas under green, red, and blue filters. The deposits were more easily recognizable on electron and fluorescence microscopy than on light microscopy. Furthermore, during fluorescence microscopy, the green filter provided the most clear visualization of lanthanum phosphate. In conclusion, fluorescence microscopy with a green filter is useful in determining the degree and extent of lanthanum deposition in the gastroduodenal mucosa., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2022, Iwamuro et al.)