Citations

Abstract Description Antigen receptor (CAR) T cells can be generated in vivo within the natural lymph node (LN) environment as the immune response to a virus infection unfolds. This in situ approach entails priming LNs with intradermal inoculations of replication defective adenoviruses encoding MHC class I and class II allo/xeno-antigens. Universal transplant antigens were devised for LN priming by introducing tryptophan into amino acid position 162 of the MHC HLA-A2:01 class I heavy chain and by using the mouse MHC class II beta chain to form chimeric class II antigens with endogenous class II alleles. The virus encoded mismatched MHC antigen presenting molecules are expressed functionally in the LN following intradermal inoculation provoking polyclonal T cells responses. Three days later CAR T cells are generated by directly injecting retroviruses encoding CARs of interest into the responding LN. Mouse CD19-specifc CAR T cells created in this manner in B6-DQ8 and DQ8/A2 mice effectively target endogenous B cells and are therapeutic in male and female Emu-myc lymphomas demonstrating the potential for the generating functional CAR T cells directly in vivo. While in situ CAR T cells are readily produced in B6, B6-IA0/DQ8, B6-IA0/DQ8/A2, and B6-IA0/DQ6 LNs, functional differences among the strains emerged in the periphery suggesting that properties of the autoimmune-associated HLA DQ8 class II allele is particularly reactive during the production of CAR T cells in vivo. Funding Sources MustangBio, Inc Mayo Clinic Center of Biomedical Research Mayo Clinic Department of Immunology Mayo Clinic Graduate School of Biomedical Science Fraternal Order of Eagles Mayo Clinic Ventures NIH R21 AI 097337 NIH R01 CA 178804 NIH T32 AI 07425 Topic Categories Tumor Immunology: Checkpoints, Prevention, and Treatment (TIPT)

Abstract Description Innate immune sensing of viral double-stranded (ds) RNA induces the transcription of hundreds of interferon stimulated genes (ISGs) that shift the cell into an antiviral state. We have shown that measles virus (MeV) utilizes the 150 kDa isoform of adenosine deaminase acting on RNA 1 (ADAR1-p150) to prevent activation of protein kinase R (PKR), thereby subverting a type-I interferon response. Hypothesizing that cytoplasmic localization of ADAR1-p150 is required for this pro-viral activity, we generated cell lines expressing single isoforms and localization mutants of ADAR1. Based on MeV replication studies in these cells, we concluded that both nuclear and cytoplasmic ADAR1-p150 prevents PKR activation. However, only cytoplasmic but not nuclear ADAR1-p110 can efficiently prevent PKR activation. These observations suggest a bimodal activation of IFN responses. Initial sensing of viral dsRNA leads to upregulation of a subset of ISGs forming p150-specific self-RNA substrates driving PKR activation. Through ADAR editome analyses, we have identified candidate p150- and p110-specific self-RNA substrates that may be the drivers of this positive feedback loop. RNA immunoprecipitation studies to identify the specific substrates of ADAR1-p150 and PKR during MeV infection are underway to strengthen this novel model of a positive feedback loop driven by self-RNAs. Altogether, our findings shift the paradigm on the regulatory properties of self-RNA on amplifying antiviral innate immunity. Topic Categories Innate Immune Responses and Host Defense: Molecular Mechanisms (INM)

Abstract Description Diffuse large B-cell lymphoma (DLBCL) is an aggressive malignancy derived from transformed B cells of germinal center (GC) or post-GC origin. DLBCL incidence is elevated in immunodeficient persons with reduced T cells, such as among HIV+ patients. Yet a causal link between T cell deficiency and DLBCL is incompletely understood. Using a mouse model of spontaneous DLBCL, we show that suboptimal T cell function, but neither zero nor full T cell function, can be a driver of B cell lymphomagenesis. In CD3δ-/- mice, which exhibit reduced number, signaling, and function of T cells, we observed progressive disruption of splenic architecture and eventual DLBCL development with ∼100% incidence. In contrast, lymphoma did not develop in wild-type mice, or CD3e-/-z-/- mice with complete T cell absence. This showed that poor-but-positive suboptimal T cells were required for GC B cell transformation and outgrowth. Mechanistically, CD3δ-/- mice exhibited altered GC dynamics at steady state and in response to immunization. Compared with wild-type mice, CD3δ-/- mice had a diminished T follicular regulatory (TFR) compartment and exhibited defective T follicular helper (TFH) cell differentiation when antigen challenged, indicating compromised regulation of the GC reaction. Indeed, defective GC B cell entry and differentiation was also observed. Our data thus suggest that suboptimal function of T helper subsets can lead to dysegulated GC reactions and B cell lymphomagenesis. Funding Sources Supported by AAI Intersect Fellowship Topic Categories Immune Response Regulation: Cellular Mechanisms (IRC)

Background: Qualification of non-invasive tests (NITs) and blood biomarkers for fibrosis severity and risk assessment is an unmet need in clinical care for cirrhosis. The paucity of reproducibility data for imaging and blood biomarkers in cirrhosis hinders their application for longitudinal monitoring. The aim of this study was to evaluate the reproducibility of imaging and blood biomarkers in a prospective cohort of adults with cirrhosis. Methods: We prospectively enrolled adults with cirrhosis in an observational, longitudinal cohort study. Participants completed a research visit with vibration-controlled transient elastography (VCTE) with liver stiffness measurement (LSM) and controlled attenuation parameter (CAP) and blood testing, including AST, ALT, platelets, alpha-fetoprotein (AFP), and the Fibrosis-4 Index (FIB-4). Biomarkers were repeated a median of 3 months apart without any interim intervention. The primary outcome was the reproducibility of each biomarker as assessed by the reproducibility coefficient (RDC%), within-participant coefficient of variation (wCV), intraclass correlation coefficient (ICC), and Bland–Altman analysis. Results: In total, 40 participants (mean age 62, 60% female, mean BMI 28.6 kg/m 2 ) had VCTE/CAP, 38 AST/ALT, and 26 had AFP at both time points. The RDC% for VCTE-LSM was 54.4, wCV 0.19, and ICC 0.91. VCTE CAP had an RDC% of 56, a wCV of 0.30, and ICC 0.47. AFP had an RDC% of 58, a wCV of 0.21, and an ICC of 0.95. RDC% for AST, ALT, and FIB-4 ranged from 70% to 79%. On Bland–Altman analyses, VCTE-LSM demonstrated the lowest relative bias (0.4%). Conclusions: Prospective assessment of repeat biomarkers in adults with cirrhosis found that VCTE-LSM and CAP provide consistent assessments across individuals but may yield substantial within-individual variation. Blood-based biomarkers had poor reproducibility within individuals but were consistent in detecting between-patient variability. These data can inform ultrasound-based non-invasive testing qualification by defining thresholds that may reflect measurement variability rather than true biologic change over time.

PURPOSE Neoadjuvant immune checkpoint inhibitors (nICIs) have demonstrated high response rates in deficient mismatch repair/microsatellite instability–high (dMMR/MSI-H) gastroesophageal adenocarcinoma (GEA). The NEONIPIGA and INFINITY trials demonstrated high rates of pathologic complete response (pCR) in this patient population. Furthermore, the INFINITY trial explored the feasibility of managing these patients nonoperatively, demonstrating promising results. This study aimed to evaluate clinical outcomes of nICIs in resectable dMMR/MSI-H GEA, with a focus on the feasibility of nonoperative management (NOM). MATERIALS AND METHODS This retrospective cohort study included patients with resectable dMMR/MSI-H GEA and treated with nICIs ± surgery at the Mayo Clinic. Patients were identified from institutional records, and clinical data were retrospectively reviewed. Primary outcomes were clinical complete response (cCR) and pCR. Secondary outcomes included event-free survival (EFS), radiologic complete response (rCR), and immune-related adverse events (irAEs). RESULTS A total of 26 patients treated between April 1, 2017, and July 30, 2025, were identified. Nine patients (34.6%) underwent surgery, of whom six (66.7%) achieved pCR. Seventeen patients (65.4%) pursued NOM, with 10 (71.4%) of 14 evaluable patients achieving cCR and 14 (82.4%) of 17 evaluable achieving rCR. One patient who initially achieved cCR had a local recurrence on surveillance endoscopy and underwent salvage endoscopic resection. At a median follow-up of 19.3 months, 15 (88.2%) of 17 patients in the NOM cohort were alive and metastasis-free, with EFS rates of 87.3% at 12 and 24 months for all patients. irAEs occurred in nine patients (34.6%), with no grade ≥3 toxicities. CONCLUSION In this retrospective cohort study, nICIs led to high cCR and pCR rates in resectable dMMR/MSI-H GEA, supporting the use of immune checkpoint inhibitors in this setting and the feasibility of NOM in select patients.

The cardiac imager should be familiar with the types of motion artifacts commonly encountered in cardiac CT, some of which can be corrected or at least minimized without having to rescan the patient.