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The fate of developing T cells is determined by the strength of T cell receptor (TCR) signal they receive in the thymus. This process is finely regulated through the tuning of positive and negative regulators in thymocytes. The Family with sequence similarity 49 member B (Fam49b) protein is a newly discovered negative regulator of TCR signaling that has been shown to suppress Rac-1 activity in vitro in cultured T cell lines. However, the contribution of Fam49b to the thymic development of T cells is unknown. To investigate this important issue, we generated a novel mouse line deficient in Fam49b (Fam49b-KO). We observed that Fam49b-KO double positive (DP) thymocytes underwent excessive negative selection, whereas the positive selection stage was unaffected. Fam49b deficiency impaired the survival of single positive thymocytes and peripheral T cells. This altered development process resulted in significant reductions in CD4 and CD8 single-positive thymocytes as well as peripheral T cells. Interestingly, a large proportion of the TCRγδ+ and CD8αα+TCRαβ+ gut intraepithelial T lymphocytes were absent in Fam49b-KO mice. Our results demonstrate that Fam49b dampens thymocytes TCR signaling in order to escape negative selection during development, uncovering the function of Fam49b as a critical regulator of the selection process to ensure normal thymocyte development and peripheral T cells survival.

The endoplasmic reticulum aminopeptidase associated with antigen processing (ERAAP) plays a crucial role in shaping the peptide-major histocompatibility complex (MHC) class I repertoire and maintaining immune surveillance. While murine cytomegalovirus (MCMV) has multiple strategies for manipulating the antigen processing pathway to evade immune responses, the host has also developed ways to counter viral immune evasion. In this study, we find that MCMV modulates ERAAP and induces an interferon γ (IFN-γ)-producing CD8+ T cell effector response that targets uninfected ERAAP-deficient cells. We observe that ERAAP downregulation during infection leads to the presentation of the self-peptide FL9 on non-classical Qa-1b, thereby eliciting Qa-1b-restricted QFL T cells to proliferate in the liver and spleen of infected mice. QFL T cells upregulate effector markers upon MCMV infection and are sufficient to reduce viral load after transfer to immunodeficient mice. Our study highlights the consequences of ERAAP dysfunction during viral infection and provides potential targets for anti-viral therapies.

Background: Approximately half of the patients with advanced pancreatic ductal adenocarcinoma (PDAC) receive subsequent lines of chemotherapy. Recently, the liposomal irinotecan (nal-IRI) plus 5-fluorouracil/leucovorin (5-FU/LV) regimen is recommended as subsequent lines of chemotherapy. However, little is known about the predictive factors for the nal-IRI + 5-FU/LV regimen, especially in patients with previous irinotecan (IRI) exposure. Objectives: We investigated the predictive factors associated with nal-IRI + 5-FU/LV treatment in patients with PDAC. Design: Multicenter, retrospective cohort study. Methods: This study included patients with advanced PDAC who received the nal-IRI + 5-FU/LV regimen for palliative purposes. Results: Overall, 268 patients were treated with nal-IRI + 5-FU/LV. The median overall survival (OS) was 7.9 months (95% confidence interval (CI): 7.0–8.8), while the median progression-free survival (PFS) was 2.6 months (95% CI: 1.9–3.2). An albumin level of<4.0 g/dL, neutrophil-to-lymphocyte ratio (NLR) of ⩾3.5, liver or peritoneal metastasis, and a history of >3 lines of palliative chemotherapy were associated with worse OS. An NLR of ⩾3.5 and liver metastasis were significant predictive factors for worse PFS. Previous exposure to IRI was not a significant predictor. Patients without prior IRI (no-IRI) treatment showed relatively longer OS and PFS compared to IRI responders and nonresponders, but these differences were not significant when compared specifically to the responders (OS: 8.8 vs 8.1 months, p = 0.388; PFS: 3.6 vs 2.6 months, p = 0.126). Conclusion: An NLR of ⩾3.5 and liver metastasis were associated with worse PFS. Prior IRI exposure was not a significant predictive factor for OS and PFS, especially in IRI responders. [ABSTRACT FROM AUTHOR]

Simple Summary: This study investigated the nationwide real-world outcomes of chemotherapy in 8651 patients with metastatic pancreatic cancer. Overall survival improved from 2012 to 2019 and was evident after the introduction of gemcitabine plus nab-paclitaxel (GnP) and FOLFIRINOX. Propensity score matching revealed no difference in overall survival between these two regimens. The findings demonstrate that advances in chemotherapy have improved survival outcomes nationally, comparing the effectiveness of GnP and FOLFIRINOX using real-world data. Background/Objectives: This nationwide population-based study investigated the overall survival (OS) of patients with metastatic pancreatic cancer (mPC) receiving first-line chemotherapy. Methods: Data from the National Health Insurance Service linked to the Korea Central Cancer Registry were used. Patients with mPC receiving first-line chemotherapy (2012–2019) were included and followed up until 2020. The gemcitabine plus nab-paclitaxel (GnP) and FOLFIRINOX groups were matched according to age, sex, and comorbidities. Results: In total, 8652 patients with mPC were treated with chemotherapy. GnP and FOLFIRINOX have been administered since 2016 and 2017, respectively. The median OS increased annually from 6 months in 2012–2013 to 10 months in 2018–2019. The median OSs in the GnP and FOLFIRINOX groups were significantly longer than those in patients receiving gemcitabine ± erlotinib. A total of 1134 patients from both the GnP and FOLFIRINOX groups were selected using propensity score matching. Before matching, the median OS was longer in the FOLFIRINOX group than in the GnP group (p = 0.0029). After matching, however, there was no significant difference in the median OS between the two groups (11 vs. 11 months, respectively, p = 0.2438). Conclusions: Patients with mPC receiving chemotherapy have shown improved OS since the introduction of GnP and FOLFIRINOX. After matching, OS did not differ between the GnP and FOLFIRINOX groups. [ABSTRACT FROM AUTHOR]

Duodenal mucosal resurfacing (DMR) by thermal ablation of the duodenal mucosa is a minimally invasive endoscopic procedure for controlling metabolic syndrome (MS). However, thermal energy can cause adverse effects due to deep mucosal injury, necessitating an additional mucosal lifting process, which complicate the procedures. Therefore, we aimed to develop a similar procedure using non-thermal photodynamic therapy (PDT) for DMR using a highly functional metal stent covered with photosensitizers (PSs) to minimize the potential risks of thermal ablation injury. We developed a novel PS stent enabling the controlled release of radical oxygen species with specific structures to prevent stent migration and duodenal stricture after ablation and performed an animal study (n = 8) to demonstrate the feasibility and safety of PDT for DMR. The stents were placed for 7 days to prevent duodenal strictures after PDT. To confirm PDT efficacy, we stained for gastric inhibitory polypeptide (GIP) and glucose transporter isoform 1. The PS stents were deployed, and PDT was applied without evidence of duodenal stricture, pancreatitis, or hemorrhage in any of the pigs. Microscopic evaluation indicated apoptosis of the mucosal cells in the irradiated duodenum on days 7 and 14, which recovered after day 28. Immunohistochemistry revealed suppressed GIP expression in the mucosal wall of the irradiated duodenum. Endoscopic PDT for DMR using PS stents could be applied safely in a porcine model and may result in decreased GIP secretion, which is a crucial mechanism in MS treatment. Further clinical studies are required to explore its safety and efficacy in patients with MS. [ABSTRACT FROM AUTHOR]