Citations

Abstract Description Inflammatory bowel disease (IBD) affects between 1-3 million people in the United States, and patients present with symptoms including diarrhea, rectal bleeding, and fatigue. ST8Sia6 is a sialic acid transferase that adds terminal a2,8 disialic acids to O-linked glycoproteins, and a SNP in ST8Sia6 is associated with Crohn’s Disease. We have found that ST8Sia6 knockout (KO) and heterozygous (het) mice exhibit a 30-fold increase in small bowel immune infiltrate, along with an increased proportion of Th1 and pathogenic Th17 CD4 cells. These mice also exhibit activated gut epithelia, increased inflammatory cytokines, and increased innate cell activation, indicative of gut inflammation. Both ST8Sia6 KO and het mice exhibit increased weight loss and decreased survival when challenged with low dose dextran sodium sulfate-induced colitis. CellChat pathway analysis demonstrates enhanced TNF and IL-1 pathway activation in ST8Sia6 KO small bowel epithelium as compared to WT mice. In addition, ST8Sia6 KO small bowel epithelium produces significantly more CCL5, which may drive immune cell migration. These data demonstrate a role for ST8Sia6 in regulating gut immune homeostasis. As TNF blockade is a first line therapy for IBD patients, elucidating the role of ST8Sia6 in regulating this pathway is critical for a mechanistic understanding of IBD pathogenesis, and this may help to improve immunotherapy options for the disease. Funding Sources NIH R01CA243545 & NIH 5T32DK124190 Topic Categories Basic Autoimmunity (BA)

Abstract Description Therapeutic in situ chimeric antigen receptor (isCAR) T cells can be generated by targeting activated T cells within a lymph node (LN) with retroviruses encoding CARs. While isCAR T cells are successfully generated by intradermal LN priming using adenovirus encoding allogeneic MHC in all mouse lines tested, differences in emerging therapeutic peripheral isCAR T cells are found in a strain dependent manner. Potentially harmful off target retroviral transduction of B cells with CARs is observed within the targeted LN. Here we report the blockade of B cell transduction using anti-CD20 antibody B cell depletion with the introduction of anti-CD19 chimeric antigen receptors into the activated CD8+ T cells. Lymphocytes were analyzed in blood and LN following isCAR T cell generation. When B cells were depleted by systemic administration of anti-CD20 antibodies during isCAR T cell induction, >97.5% systemic depletion of B cells was achieved. Whereas very small numbers of CAR transduced B cells were found in the blood of mice not treated with anti-CD20, none were observed in animals systemically depleted of B cells. In contrast, CAR B cells persisted in the LN of local anti-CD20 treated animals. However, animals expressing dominant CD8+ isCAR T cell populations eliminated LN B cells expressing CARs by week two. Furthermore, systemic treatment of lymphoma in animals with anti-CD20 antibody complemented anti-CD19 isCAR T therapy while blocking off target B cell transduction. Funding Sources Mayo Clinic Ventures Mayo Clinic Graduate School of Biomedical Sciences Mayo Clinic Topic Categories Tumor Immunology: Checkpoints, Prevention, and Treatment (TIPT)

Abstract Description B7-H3 is a member of the B7 superfamily, which includes co-inhibitory receptors such as B7-H1/PD-L1 and co-stimulatory receptors such as B7-1/CD80 and B7-2/CD86. B7-H3 is upregulated by almost all types of tumors and is associated with worse prognosis. However, the exact mechanism by which B7-H3 suppresses anti-tumor immune response remains to be discovered as its ligand has yet to be identified. Sialic acid modifications are also increased in many cancers and are similarly associated with poor outcome. Here, we demonstrate for the first time that sialylated B7-H3 binds to the immune inhibitory receptor Siglec-9. Siglec-9 is expressed on many immune cells, including NK cells and T cells. We have shown that B7-H3 expression on target cells reduces killing by Siglec-9 expressing NK cells in vitro. We then hypothesized that antibodies that block B7-H3 binding to Siglec-9 will be an effective intervention to boost anti-tumor immunity. We have generated a high affinity anti-B7-H3 monoclonal antibody, F7, which blocks B7-H3 binding to Siglec-9. F7 functions to enhance NK cell killing of B7-H3 expressing target cells in vitro. F7 also dramatically enhances CART19 mediated killing of B7-H3 expressing Nalm6 cells in a relapse model in NSG mice in vivo. In summary, our work has demonstrated that B7-H3 binds Siglec-9, and blockade of such interaction can enhance anti-tumor immunity. Funding Sources • Mayo Clinic Center for Biomedical Discovery • NIH Glycobiology Common Fund supplement to R01CA243545-01A1 to VSS Topic Categories Tumor Immunology: Checkpoints, Prevention, and Treatment (TIPT)

Abstract Description PBC is an archetypal autoimmune disease where the dominant autoantigen is mitochondrial PDC-E2. Hitherto, PBC treatment has been neither specific nor directed toward restoration of tolerance. CNP-104, a tolerogenic nanoparticle encapsulating PDC-E2, is hypothesized to restore tolerance to pathogenic T cells. We conducted a Phase 2a First-in-Human randomized controlled trial of CNP-104 in PBC patients unresponsive/intolerant to ursodeoxycholic acid. The 42 enrolled subjects were randomized 2:1 to receive two doses of CNP-104 or placebo (PBO) one week apart and were followed for 120 days to assess safety and treatment durability. CNP-104 was safe and well-tolerated. Compared to PBO, the CNP-104 group had a reduced percentage of antigen-specific Th17 T cells and increased antigen-specific tolerogenic CD8+ T cell counts (TIGIT, GARP). ALP, ALT, and total bilirubin were similar between groups. Clinically relevant effects on albumin levels, liver stiffness, and the rate of change in 5-year UK-PBC risk for liver outcomes were improved in the CNP-104 group compared to PBO. This trial is limited by small size and data variability. Induction of antigen-specific T cell tolerance, shown by reduced Th17 cells and increased TIGIT and GARP cells correlates with improved liver stiffness, albumin, and UK-PBC. These findings suggest the CNP-104 tolerogenic mechanism of action translates to clinical benefits. These data support future studies with this unique therapeutic platform to treat PBC. Topic Categories Therapeutic Approaches to Autoimmunity (THER)

Abstract Description During the humoral immune response, B cells undergo rapid metabolic reprogramming with a high demand for nutrients, which are vital to sustain the formation of the germinal centers (GCs). Rag-GTPases sense amino acid availability to modulate the mechanistic target of rapamycin complex 1 (mTORC1) pathway and suppress transcription factor EB (TFEB) and transcription factor enhancer 3 (TFE3). However, how Rag-GTPases coordinate amino acid sensing, mTORC1 activation, and TFEB/TFE3 activity in humoral immunity remains undefined. Here, we show that B cell-intrinsic Rag-GTPases are critical for the development and activation of B cells. RagA/RagB deficient B cells fail to form GCs, produce antibodies, and generate plasmablasts in both T-dependent (TD) and T-independent (TI) humoral immune responses. Deletion of RagA/RagB in GC B cells leads to abnormal dark zone (DZ) to light zone (LZ) ratio and reduced affinity maturation. Mechanistically, the Rag-GTPase complex constrains TFEB/TFE3 activity to prevent mitophagy dysregulation and maintain mitochondrial fitness in B cells, which are independent of canonical mTORC1 activation. TFEB/TFE3 deletion restores B cell development, GC formation in Peyer’s patches and TI humoral immunity, but not TD humoral immunity in the absence of Rag-GTPases. Collectively, our data establish Rag-GTPase-TFEB/TFE3 pathway as an mTORC1 independent mechanism to coordinating nutrient sensing and mitochondrial metabolism in B cells. Funding Sources National Institute of Allergy and Infectious Diseases (NIAID) - AI162678 National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) - AR077518 Topic Categories Immune Response Regulation: Molecular Mechanisms (IRM)

Abstract Description This study dissects mechanisms of spontaneous tumor rejection leading to better understanding of successful immune responses to cancer. Cancers persist despite expression of tumor-specific neoantigens promoting ongoing anti-tumor immune responses. While some occult tumor cells likely are cleared by effective anti-tumor immune responses, the targeted antigens are not easily identifiable as those cells spontaneously disappear. Congenic mouse breast carcinoma models expressing a defined protein mimicking neoantigens were used to dissect the protective spontaneous immune response. BALB/c (MHC H-2d) mice challenged with BALB/c breast tumors expressing the rat-erbB2 oncoprotein succumb to their tumors despite demonstrated tumor immunogenicity, mimicking known patient responses to cancer. Meanwhile, H-2b positive BALB.B and H-2d/H-2b F1 hybrid mice spontaneously eliminate genetically matched tumors in an MHC-II dependent manner. CD4+ T-cells and B-cells or the rat-erbB2-specific antibodies they produce are crucial mediators of this protective response. Differences in the tumor microenvironments in rat-erbB2+ tumor-bearing BALB.B and BALB/c mice at the time of fate decision in the models reflect the differences between effective and ineffective anti-tumor immunity. Identifying the nature of the optimal MHC-II antigens, how they activate protective CD4+ T-cells, and the interactions that promote protective antibodies will better inform future cancer therapies. Funding Sources Bernie Fineman Research Fund Mayo Clinic Center for Biomedical Discovery Mayo Clinic Department of Immunology Mayo Clinic Graduate School of Biomedical Sciences NIH Traning Grant 5 R25 GM 55252 Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

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)

Early postprandial glucagon concentrations are higher in type 1 diabetes (T1D) than in individuals with no diabetes (ND). To determine the cause, we infused stable [13C9, 15N1]glucagon before, during, and after a mixed meal in 16 ND and 16 T1D individuals to measure glucagon turnover. In a subcohort of 9 ND and 12 T1D individuals, we estimated [13C9, 15N1]glucagon kinetics during steady state. A linear, single-compartment model described [13C9, 15N1]glucagon kinetics and allowed precise estimation of the volume of distribution (VD) and clearance rate (CL). Model parameters were similar between groups, with the VD of [13C9, 15N1]glucagon at 42.1 ± 3.3 mL/kg, implying that [13C9, 15N1]glucagon distributes in a single compartment and with VD approximating the plasma volume and CL at 10.6 ± 0.9 mL/kg/min. Higher early (0–120 min after meal ingestion) postprandial glucagon concentrations (1,907.9 ± 373.4 vs. −93.6 ± 240.5 pg/mL · 120 min P < 0.001) observed in T1D was due to higher rates of glucagon appearance (3.39 ± 2.8 vs. −3.95 ± 2.0 ng/kg · 120 min, P < 0.04) and disappearance (2.13 ± 2.6 vs. −5.28 ± 2.1 ng/kg · 120 min, P < 0.04) compared with ND. We have determined postprandial glucagon turnover in humans and have demonstrated that changes in postprandial glucagon concentrations in T1D are due to increased rates of glucagon turnover during the early postprandial period. Article Highlights This study was conducted to determine postprandial glucagon metabolism in people with and without type 1 diabetes. We wanted to determine the cause for higher early postprandial glucagon concentrations in type 1 diabetes. We found that higher early postprandial glucagon turnover is the cause of higher early postprandial glucagon concentrations in type 1 diabetes Strategies that decrease early post prandial glucagon fluxes could improve postprandial glucose concentrations in type 1 diabetes.

ABSTRACT Background Given the Centers for Medicare and Medicaid Services' coverage of screening CT colonography (CTC) beginning in January 2025, we evaluated the cost‐effectiveness of CTC for colorectal cancer (CRC) screening by race (Black and White) and gender, considering real‐world screening adherence. Methods A microsimulation model compared CRC screening strategies in average‐risk adults by race and gender, incorporating 2010–2019 U.S. data on disease progression and real‐world screening adherence for colonoscopy and fecal immunochemical test (FIT). Five strategies were compared: (1) status quo (choice between colonoscopy and FIT); (2) CTC every 5 years; (3) colonoscopy every 10 years; (4) annual FIT; and (5) multitarget stool DNA test every 3 years, plus no screening. Lifetime costs, quality‐adjusted life years gained (QALYG), and incremental cost‐effectiveness ratios were projected. A willingness‐to‐pay threshold of $100,000/QALYG was used. Results Under the status quo, Black adults showed higher CRC cases and greater utilization for FIT over colonoscopy than White adults. Compared to the status quo, the CTC strategy yielded more QALYG and fewer CRC cases among Black adults, but fewer QALYG and more CRC cases among White adults. Both status quo and CTC strategies outperformed other strategies across races. The CTC strategy was the dominant strategy for Black adults. For White adults, the status quo was cost‐effective with incremental cost‐effectiveness ratios of $34,998–$73,428/QALYG, while the CTC strategy was cost saving compared to no screening. Conclusions CTC could be cost‐effective for CRC screening in Black adults under real‐world screening adherence, supporting Medicare coverage to address specific population needs and structural barriers to screening.