Citations

Background Sudden cardiac death (SCD) is the leading cause of duty‐related death among firefighters. Understanding postmortem cardiovascular abnormalities associated with SCD is critical to guiding fire service cardiovascular disease screening and prevention programs. Methods This study included US firefighters who had a duty‐related death over a 16‐year period (1999–2014) with available postmortem reports (autopsy/medical examiner reports). Cases were systematically reviewed to identify cases of SCD. For each SCD case, the primary etiology of SCD was adjudicated by experts in sports cardiology and cardiovascular pathology. Results Postmortem evaluations were available for 794 of 2100 (37.8%) on‐duty firefighter deaths over the study period (average age, 44±13 years; age range, 17–82 years; 4.0% women). A total of 312 of 794 (39.3%) firefighter deaths were adjudicated as SCD. A total of 255 of 312 (81.8%) SCD events were attributable to coronary artery disease/ischemic heart disease or hypertensive heart disease, which both are associated with traditional cardiovascular risk factors. The leading etiology of SCD among young firefighters (aged <40 years) was also coronary artery disease/ischemic heart disease (24/50 [48.0%]). Of firefighters who had an exertional SCD event thought to be secondary to coronary artery disease (n=97), a total of 62 of 91 (68.1%) had severe fixed coronary stenosis, while 29 of 91 (31.9%) demonstrated acute plaque rupture/thrombosis. Conclusions More than 80% of on‐duty SCD events among US firefighters are due to coronary artery disease and hypertensive heart disease that may be prevented by early disease identification and risk factor modification. Future studies should assess the efficacy of more rigorous firefighter cardiovascular disease screening and management practices.

Abstract Introduction Checkpoint blockade revolutionized cancer therapy. However, only a small proportion of cancers respond to checkpoint blockade. B7-H3 is a member of the B7 superfamily, which includes both co-inhibitory and co-stimulatory receptors. B7-H3 is upregulated by many tumors which is generally associated with a worse prognosis. However, the exact mechanism by which B7-H3 suppresses the immune response remains elusive. Methods We transfected human HEK293T cells and assessed the binding to recombinant Siglecs via flow cytometry. We generated monoclonal antibody F7 against human B7-H3 and tested its blocking function using B7-H3 transfected HEK293T cells. We examined the extent of degranulation and NK cell-mediated killing on B7-H3 expressing HEK293T cells in vitro, as well as the CART19 cells mediated killing in relapse model of B7-H3 expressing CD19+ leukemia Nalm6 cells NSG mice. Results We demonstrated that sialylated B7-H3 binds to the inhibitory receptor Siglec-9 on immune cells but not to the related protein Siglec-7. A high affinity monoclonal antibody (mAb) F7 against B7-H3 blocks Siglec-9 binding. Functionally, F7 enhances 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. Conclusion We have now shown for the first time that B7-H3 binds to the inhibitory receptor Siglec-9 and generated a novel monoclonal antibody F7 that target a unique sequence in B7-H3 as compared to other monoclonal antibodies being examined for clinical efficacy. F7 can promote NK cell killing of B7-H3 expressing target cells in vitro and synergize with CART19 to enhance killing of B7-H3 expressing tumor cells in vivo. As B7-H3 is overexpressed in many human cancers, this work is critical toward understanding how B7-H3 mediates immune evasion through Siglec-9 for enhancing anti-tumor immunity. Funding Source R01CA243545-01A1 Topic Categories Tumor Immunology: Checkpoints, Prevention, and Treatment (TIPT)

Abstract Introduction Generation of T cells requires dynamic epigenetic alteration of histones to control gene expression at each developmental stage. Histone acetyltransferases (HATs) and histone deacetylases (HDACs) facilitate addition or removal of various acyl groups from lysine residues, including acetylation (KAc) and crotonylation (KCr). The Class I deacetylases HDAC1, HDAC2, and HDAC3 have been shown to have 3 functions: adaptor, decrotonylase, and deacetylase activity. The relative importance of each function in T cells is not known. Genetic knockout of HDAC3 in mice using CD2icre results in a severe block in T cell development and spontaneous development of severe colitis. Our lab determined that HDAC3 is required for three different aspects of this process: CD4+CD8 + (DP) cell survival, positive selection, and CD4+ lineage commitment. We generated a novel mouse model with CD2icre-mediated deletion of endogenous HDAC3 and linked re-expression of HDAC3 “VRPP” mutant mice, which maintained adaptor function but lacks enzymatic activity. Strikingly, these mice do not develop spontaneous colitis even up to one year of age. Methods We used flow cytometry to assess T cell development and maturation in the thymus, spleen, mLN, and colon of HDAC3 cKO vs. HDAC3 VRPP mice. CUT&RUN was utilized to determine differences in H3K9Ac, H3K27Ac, and H3K18Cr across CD8 and CD4 lineage genes. H&E was utilized to assess structural changes in thymus and colon. Results Similar to CD2icre HDAC3 cKO mice, HDAC3 VRPP mice have a block in positive selection due to failure to down regulate RORγt and decreased DP cell survival due to increased expression of P2RX7. Although fewer T cells are produced in HDAC3 VRPP mice, CD4+ lineage commitment is restored, likely mitigating the development of spontaneous colitis. Conclusion Our results demonstrate that HDAC3 enzymatic activity is necessary for several aspects of T cell development, while HDAC3 adaptor function is sufficient to restore CD4+ lineage commitment. Funding Source NIAID RO1 AI150100, T32 AI170478 Topic Categories Hematopoiesis and Immune System Development (HEM)

Abstract Aims Routine aspirin use for primary prevention yields modest cardiovascular benefit but increases bleeding risk in average-risk adults. Whether individuals with elevated lipoprotein(a) [Lp(a)] levels or high-risk LPA variants derive greater benefit remains uncertain. Methods and results Following Cochrane and PRISMA guidelines, we systematically searched PubMed/MEDLINE, Embase, and Cochrane Central for studies of adults without ASCVD, elevated Lp(a) (≥50 mg/dL), high-risk LPA genotypes, or elevated genetic risk scores, comparing aspirin vs. no aspirin use. Random-effects meta-analyses using restricted maximum-likelihood (REML) estimation with Hartung–Knapp–Sidik–Jonkman (HKSJ) adjustment were used to pool hazard ratios (HR) and 95% confidence intervals (CI). In six studies, 6628 participants were included. Pooled random effects showed no significant reduction in major adverse cardiovascular events (MACE) with aspirin (HR = 0.60; 95% CI 0.31–1.17; P = 0.1) or clinical bleeding events (HR = 1.24; 95% CI 0.83–1.87; P = 0.18). Subgroup analyses showed a nonsignificant reduction MACE among elevated Lp(a) (HR = 0.63; 95% CI 0.16 to 2.49; P = 0.284) and statistically significant reduction among LPA rs3798220 carriers (HR = 0.37; 95% CI 0.19 to 0.71; P = 0.003), though this finding was not consistent in the sensitivity analyses. Conclusion Among adults without ASCVD but with elevated Lp(a) or high-risk LPA genotypes, aspirin use did not confer a statistically significant cardiovascular benefit and was associated with numerically higher bleeding risk. The apparent reduction seen in rs3798220 carriers was inconsistent and likely reflects small-sample bias.

BACKGROUND: While health systems have implemented resources to improve lipid management in people with atherosclerotic cardiovascular disease, the population-level effectiveness is unclear. METHODS: Electronic health record data from patients with atherosclerotic cardiovascular disease between January 1, 2021, and December 31, 2023, across 16 US academic health systems were analyzed. Atherosclerotic cardiovascular disease (defined by diagnosis and procedure codes) was established on or before the index date defined as the date of the most recent LDL-C (low-density lipoprotein-cholesterol) or the last day of the study period for those without an LDL-C available. Systems were surveyed to identify lipid management programs (eg, prevention/lipid clinic, electronic health record–based tools, and lipid management algorithms). Sequential multilevel multivariable logistic regression modeling was used to (1) assess the system-level association between an LDL-C <70 mg/dL and the presence of lipid management programs, adjusting for patient-level demographic and clinical characteristics, and (2) whether system-level uptake of statin or nonstatin lipid-lowering therapy was associated with an LDL-C <70 mg/dL. RESULTS: We included 1 738 042 patients with atherosclerotic cardiovascular disease (median, 88 365 per system; range, 17 086–2 48 371). About 81% of the health systems had prevention or lipid clinics. The proportion of those on statins ranged from 31.0% to 60.4% across health systems (median, 46.3%). Lower proportions were observed in the use of high-intensity statins (16.2%–33.1%), nonstatins (2.6%–8.1%), and combination lipid-lowering therapy (1.7%–6.3%). Among those with an LDL-C level available (n=890 521), 42.5% had an LDL-C <70 mg/dL, ranging 35.8% to 49.4% across systems. There was no association between the odds of achieving LDL-C <70 mg/dL and health system lipid management algorithm, prevention clinics/lipid clinics, or electronic health record–based tools. Neither system-level high-intensity statin utilization nor nonstatin use was associated with an LDL-C <70 mg/dL. CONCLUSIONS: Despite variability in lipid management resources and lipid-lowering therapy use across systems, many did not reach an LDL-C <70 mg/dL, and there was low uptake of lipid-lowering therapy. Innovative implementation strategies are needed for system-level lipid management.

Abstract Description Generation of T cells requires dynamic epigenetic alteration of histones to control gene expression at each developmental stage. The Class I deacetylases HDAC1, HDAC2, and HDAC3 have been shown to have 3 functions: adaptor, decrotonylase, and deacetylase activity. The relative importance of each function in T cells is not known. CD2icre HDAC3 cKO mice develop severe colitis and demonstrate that HDAC3 is required during thymocyte development for positive selection, DP survival, and CD4 lineage commitment. Recently, a mutation was identified in HDAC3 that eradicated deacetylase activity (“VRPP”). We generated a novel mouse model with Cre-mediated deletion of endogenous HDAC3 and linked re-expression of HDAC3 VRPP, which maintained adaptor function but lacks both deacetylase and decrotonylase enzymatic activity. Similar to CD2icre HDAC3 cKO mice, HDAC3 VRPP mice have a block in positive selection due to failure to down regulate RORγt and decreased DP cell survival due to increased expression of P2RX7, demonstrating that HDAC3 enzymatic activity is required for these functions. However, when the positive selection defect is bypassed in HDAC3 VRPP mice, CD4+ lineage commitment is restored. Strikingly, this mouse does not develop spontaneous colitis even up to one year of age, although T cell development is still impaired. Thus, there are different roles for HDAC3 enzymatic vs. adaptor function during T cell development which are made evident in HDAC3 VRPP mice. Funding Sources NIAID RO1 AI150100; T32 AI170478; Mayo Clinic Graduate School of Biomedical Sciences Topic Categories Lymphocyte Differentiation and Peripheral Maintenance (LYM)

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 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)

Introduction: Apolipoprotein B (ApoB) and coronary artery calcium score (CAC) are well-established risk factors for coronary heart disease (CHD). However, the interaction between these risk factors on CHD risk has not been well-studied. We investigated the association between ApoB levels and CAC with CHD risk. Methods: We analyzed 4,649 participants from the Multiethnic Study of Atherosclerosis cohort (median follow-up 13.9 years) without baseline CHD or statin use. High ApoB was defined as ≥120 mg/dL. Participants were divided into 6 groups; group 1: CAC = 0 with normal ApoB, group 2: CAC = 0 with high ApoB, group 3: CAC 1-99 with normal ApoB, group 4: CAC 1-99 with high ApoB, group 5: CAC ≥100 with normal ApoB, group 6: CAC ≥100 with high ApoB. CHD was defined as myocardial infarction, resuscitated cardiac arrest, or CHD death. Survival analysis using Kaplan-Meier and multivariable Cox proportional hazard models were performed to assess the relationship between ApoB, CAC, and time to first CHD event. Results: In an adjusted model, high ApoB, CAC (1-99), and CAC (≥100) were independently associated with CHD (HR: 1.48; 95% CI: 1.04, 2.11; HR: 2.54; 95% CI: 1.78, 3.64; and HR: 4.41; 95% CI: 3.08, 6.31, respectively). Compared to group 1 (CAC 0 with normal ApoB), CAC 0 and high ApoB (group 2) was not associated with increased risk of CHD (HR: 1.15; 95% CI: 0.59, 2.23). However, a statistically significant greater risk of CHD was observed in those with CAC 1-99 and normal ApoB (group 3) (HR: 2.12; 95% CI: 1.37, 3.28), CAC 1-99 and high ApoB (group 4) (HR: 4.12; 95% CI: 2.42, 7.00), CAC ≥100 and normal ApoB (group 5) (HR: 4.20; 95% CI: 2.78, 6.34), CAC ≥100 and high ApoB (group 6) (HR: 5.72; 95% CI: 3.40, 9.63). Conclusions: In this analysis, ApoB and CAC are independently associated with CHD risk. Individuals with high ApoB and CAC ≥100 had the highest risk of CHD. In contrast, individuals with CAC = 0 and high ApoB had no significant increase in CHD risk compared to individuals with normal ApoB levels. These findings suggest that ApoB and CAC may be complementary tools for CHD risk stratification in the context of primary prevention.