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IntroductionNatural killer (NK) cells play a pivotal role in immune surveillance in the liver. We aimed to identify potential targets for NK cell-mediated immune intervention by revealing the functional molecules on NK cells in HCC patients.MethodsTo evaluate the impact of aging on NK cell phenotypes, we examined NK cells from healthy volunteers (HVs) of various ages. Because ILT2 expression on CD56dim NK cells increased with increasing age, we enrolled age-matched HCC patients and HVs. We determined the NK cell phenotypes in blood mononuclear cells (PBMCs) and intrahepatic lymphocytes (IHLs) from cancerous and non-cancerous tissues. We evaluated cytotoxicity and antibody-dependent cellular cytotoxicity (ADCC) of NK cells in vitro.ResultsILT2-positive CD56dim NK cells in PBMCs were increased in HCC patients compared with HVs. In HCC patients, ILT2-positive CD56dim NK cells were increased in cancerous IHLs compared with non-cancerous IHLs and PBMCs. We examined the impact of macrophage migration inhibitory factor (MIF) on ILT2 expression in co-cultures of HCC cells and NK cells. The enhanced expression of ILT2 on CD56dim NK cells from HCC patients was inhibited by masking antibodies against MIF and CXCR4. ILT2-positive CD56dim NK cells exhibited lower capacities for cytotoxicity and ADCC than ILT2-negative cells, which were partially restored by ILT2 blockade.ConclusionsIn HCC patients, ILT2 is a signature molecule for cancerous CD56dim NK cells with impaired cytolytic capacity. The MIF-CXCR4 interaction is associated with ILT2 induction on CD56dim NK cells and ILT2 serves as a target for functional NK cell restoration.

Abstract This review discussed analyzing information dissemination and activities related to mental health conducted by the Centers of Disease Control and Prevention (CDC), considering their application in Japan, and disseminating them to the public is necessary for the Japanese New Center for Health Control. The Japanese government also explores the Japanese New Center For Health Control in addressing children's mental health issues potentially under the Japan health crisis. The findings underscore the urgency of prioritizing children's mental health and implementing effective strategies to mitigate the long‐term effects of the COVID‐19 pandemic.

Objectives: To investigate the role of immunogenicity after the third vaccine dose against Omicron infection and COVID-19-compatible symptoms of infection. Methods: First, we examined vaccine effectiveness (VE) of the third dose against the second dose during the Omicron wave among the staff at a tertiary hospital in Tokyo. In a case-control study of third vaccine recipients, we compared the preinfection live-virus neutralizing antibodies (NAb) against Omicron between breakthrough cases and their controls who had close contact with patients with COVID-19. Among these cases, we examined the association between NAb levels and the number of COVID-19-compatible symptoms. Results: Among the 1456 participants for VE analysis, 60 breakthrough infections occurred during the Omicron wave. The third dose VE for infection was 54.6%. Among the third dose recipients, NAb levels against Omicron did not differ between the cases (n = 22) and controls (n = 21). Among the cases, those who experienced COVID-19-compatible symptoms had lower NAb levels against Omicron than those who did not. Conclusion: The third vaccine dose was effective in decreasing the risk of SARS-CoV-2 infection during Omicron wave compared with the second dose. Among third dose recipients, higher preinfection NAb levels may not be associated with a lower risk of Omicron infection. Contrarily, they may be associated with fewer symptoms of infection.

Abstract Background Gallbladder neuroendocrine neoplasm is a rare disease that is divided into neuroendocrine tumors (NETs) and neuroendocrine carcinomas (NECs). Clear cell NETs of the gallbladder are extremely rare. We report the case of a patient with polypoid clear cell NET G1 of the gallbladder who underwent laparoscopic cholecystectomy. Case presentation A 10-mm pedunculated polyp in the gallbladder neck was detected on a follow-up abdominal ultrasound in a 60-year-old man with chronic hepatitis and hepatitis B without medication. Six months later, an abdominal ultrasound revealed that the tumor had enlarged to 12 mm in size. He was asymptomatic and had no abnormalities in other laboratory examinations, including the tumor markers, carcinoembryonic antigen and CA19-9. Abdominal ultrasound showed a 12-mm polyp in the neck of the gallbladder with perfusion and focal thickening of the gallbladder wall. A gallbladder stone was also seen in the fundus. An enhanced computed tomography scan and magnetic resonance imaging revealed a polypoid lesion and gallbladder stone located at the neck of the gallbladder and the fundus, respectively. Malignancy could not be excluded, and hence, a laparoscopic cholecystectomy was performed. Pathologically, a pedunculated polyp (14 × 11 × 15 mm) was observed in the neck of the gallbladder, and the polypoid lesion comprised nests or trabecular growths of clear NET cells in the lamina propria (ENETS: T1N0M0; AJCC: T1aN0M0). Immunohistochemical staining with synaptophysin, chromogranin A, and CD56 was confined to the tumor. The pathological diagnosis was clear cell NET G1 of the gallbladder. Although clear cell NET is often described as a distinct manifestation of von Hippel-Lindau disease (VHL), the patient had no past medical or family history of VHL. Until his one-and-a-half-year follow-up, the patient was doing well and without any signs of recurrence. Conclusion We report an extremely rare case of gallbladder clear cell NET G1. When NET G1 is incidentally identified in a gallbladder surgical specimen, clinical information and pathological findings should be considered as references.

Abstract Background Methotrexate (MTX) is a frequently used drug in the treatment of rheumatoid arthritis (RA), but occurrences of lymphoproliferative disorders (LPD) have been reported in patients undergoing an MTX regimen. Almost half of the patients with methotrexate-associated lymphoproliferative disorders (MTX-LPD) have extranodal lesions; moreover, although extremely rare, digestive tract perforations resulting from the extranodal lesions of MTX-LPD have also been reported. Case presentation We describe the case of an 81-year-old woman with RA who had been prescribed MTX at 6 mg per week for the past 11 years. She was admitted to our hospital with occasional abdominal pain and was first diagnosed with enteritis. Her abdominal pain did not improve, and a computed tomography scan showed abdominal effusion and free air in the abdominal cavity. She was diagnosed with a digestive tract perforation and underwent emergency surgery. The perforation site was identified in the jejunum, and she underwent small intestinal resection around the perforated region. The pathological findings showed an ulcer in the jejunum and infiltration of large atypical lymphocytes around the perforated region. An immunohistochemical examination revealed the expression of a cluster of differentiation 20 and latent membrane protein 1. Considering the patient’s history of RA treated with MTX, she was diagnosed as having Epstein–Barr virus (EBV)-related MTX-LPD with a histological diagnosis of EBVMCU. MTX was discontinued after the surgery, and her soluble interleukin-2 receptor (sIL-2R) levels had returned to normal 1 year later. She has had a good course for the 2 years since surgery and remains asymptomatic with no recurrence of MTX-LPD, as confirmed by the sIL-2R levels. Conclusion We experienced a rare case of the jejunum perforation induced by MTX-LPD. Since only a few cases have been reported of a patient with small intestinal perforation induced by MTX-LPD, further research is necessary to evaluate the clinicopathological features of MTX-LPD. The patient had disease remission after surgery and by discontinuing MTX treatment; our case did not require chemotherapy. EBV-positive patients, especially those with a pathological presentation of EBVMCU, could have a higher likelihood of remission, which could have been a factor in the present case.