Citations

Abstract Description The efficacy of immunotherapy for splenic marginal zone lymphoma (SMZL) remains limited due to the strong immune suppression present in the tumor microenvironment (TME). Tregs play a key role in maintaining TME homeostasis by suppressing effector T cells and malignant B cells. Previously, we identified two Treg subsets CD26+ and CD161+ in SMZL. CD161+ Tregs were more effective at suppressing both CD8+T cells and malignant B cells, whereas CD26+Tregs primarily inhibited CD8+T cells. Patients with higher levels of CD26+ Tregs and fewer CD161+ Tregs tend to have worse outcomes. In this study, we found that cytokine-inducible SH2-containing protein (CISH), a known negative regulator of immune activation, is highly expressed in CD26+Tregs compared to CD161+ Tregs. Co-culturing B cells enhanced the expression of CISH and CD26 in CD4+CD25- Treg cells, knockdown of CISH in Tregs reduced CD26 expression and their immune suppression activity of CD8+T cells, while CRISPR knockout of CISH in Karpas 299 cells led to higher expression CD70, a molecule associated with less immunesuppression. Our findings suggest that increased CISH expression in Tregs could result in increased immune suppression and unfavorable outcome in SMZL, suggesting CISH is a potential therapeutic tagrget in SMZL by dempening immunosuppressive property of the Treg cells hence boosting the antitumor immunity. Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

Abstract Description In the tumor microenvironment of glioblastoma, myeloid cells act as a double-edged sword—they are a major cellular component suppressing the immune response while serving as a promising therapeutic target. Our study sheds light on the voltage-gated proton channel Hv1, predominantly expressed in myeloid cells, as a pivotal regulator of their physiological functions. Elevated Hv1 expression correlates strongly with poor prognosis in glioblastoma patients, underscoring its clinical significance. Using a glioma mouse model, we demonstrated that Hv1 depletion markedly extended survival. To overcome the limitations of existing tools, we engineered novel transgenic mouse lines optimized for Hv1 research. Our findings revealed tumor-induced Hv1 upregulation, with glioma-associated macrophages identified as the principal contributors. Crucially, we identified that Hv1 in infiltrating macrophages as the major driver of survival phenotype differences. Through a multi-faceted approach combining in vivo two-photon imaging, spectral flow cytometry, and spatial transcriptomic sequencing, we discovered that Hv1 depletion limits macrophage infiltration and enhances antigen presentation, ultimately fostering a stronger adaptive immune response. These findings establish the Hv1 channel as a crucial new immune regulator within the brain tumor milieu, offering a promising target for reprogramming macrophage function to combat glioblastoma. Funding Sources Supported by NIH R35NS132326 (LJW); Mayo Clinic Cancer Center and Mayo Clinic Center for Biomedical Discovery. Topic Categories Neuroimmunology (NEUR)

Background Preclinical studies demonstrate the benefits of ultra‐high dose‐rate (FLASH) radiation, reducing normal tissue toxicity while maintaining tumoricidal effects. Proton FLASH (pFLASH) studies typically use transmission beams, missing the normal tissue‐sparing advantage of the spread‐out Bragg peak (SOBP). Purpose This study aims to propose and implement a series of modifications to enable a clinical Mevion S250i gantry‐mounted synchrocyclotron to deliver pFLASH within the SOBP of the proton beam. Methods A clinical synchrocyclotron was modified to enable FLASH proton beam delivery using the Mevion FLASH accessory kit, a commercially available tool that allows for the delivery of a single spot SOBP at FLASH dose rates. To ensure accurate beam monitoring, a Faraday cup was utilized to measure the integral charge per delivery at different dose rates and calibrate the FLASH transmission ion chamber (FLASHTic), which is integrated in the FLASH accessory mount attached to the nozzle of the gantry. The FLASHTic was specifically designed to prevent saturation at the dose rates associated with FLASH. To generate the desired single spot SOBP, boron carbide absorbers, a range modulating hole filter, and an 11‐mm‐diameter circle brass aperture were employed on the FLASH nozzle mount. Results The results indicate that the FLASHTic measurements demonstrated a strong correlation with the Faraday cup post calibration, suggesting that the FLASHTic can be effectively utilized for both monitoring and terminating the proton beam. The 80%–80% width of the SOBP was 2.01 cm. The peak dose rate at the SOBP proximal peak reached 105.03 Gy/s, with an average of 96.18 Gy/s over five days. Transitioning between FLASH and clinical mode required less than one hour without affecting the clinical beam. Conclusions The commissioning of a 230 MeV proton synchrocyclotron for SOBP FLASH delivery was achieved, providing a platform for preclinical small animal studies on pFLASH effects.

Background Spontaneous intracranial hypotension (SIH) results from cerebrospinal fluid (CSF) leakage due to spinal dural tears or CSF–venous fistulas. Orthostatic headache is the hallmark presentation, though severe downward displacement of the brainstem may lead to altered consciousness or coma. Definitive treatments include targeted epidural blood patches, venous embolization, or surgical repair. Methods This article reviews the role of the Trendelenburg position as a temporizing measure in the acute management of SIH. We describe the correct technique, physiologic rationale, and practical considerations for its application, with attention to both therapeutic and diagnostic utility. Discussion Positioning the patient with the feet elevated above the head can reduce brain sag and provide short-term symptomatic relief while awaiting definitive treatment. Although the Trendelenburg position is widely used in practice, supporting evidence remains limited, and clinicians must be aware of its benefits, indications, and inherent limitations. Its appropriate application may assist in stabilizing patients with acute or severe SIH, particularly those with impaired consciousness, until more definitive interventions are pursued.

Abstract Objective β-Catenin–mutated hepatocellular adenomas (HCAs) carry an increased malignant transformation risk and are screened by interpreting glutamine synthetase (GS) and β-catenin by immunohistochemistry (IHC). Our study aims to assess GS and β-catenin interpretation guidelines for applicability and reproducibility in predicting high-risk HCA and other relevant molecular alterations. Methods Hematoxylin and eosin (H&E), β-catenin, GS, and CD34 stains from 75 HCAs were interpreted by three pathologists using Method A (GS interpretation: negative, perivenular patchy, map-like, diffuse, and indeterminate) and Method B criteria (similar GS interpretation scheme based on a recent publication, with and without CD34 expression patterns). Ease of application and interpretation confidence level were assessed. High-risk IHC was defined as nuclear β-catenin and/or diffuse homogeneous GS. Molecular testing was performed on a subset of HCAs and controls. Results There were 57 resections and 18 biopsy specimens examined. Methods A and B (GS only) were rated as easy to apply, with high interpretation confidence (≥90% using both methods). Consensus rate was comparable in biopsy specimens (100% for both methods) and resections (88% for Method A, 93% for Method B). While the same cases were stratified into high-risk GS categories using both systems, clinically significant genetic alterations (TERT promoter, EGFR, MTOR, and TP53) were identified in 25% of cases stratified as not high risk by IHC. Conclusions Both methods have a similar ease of application and level of interpretation confidence, and they also detected β-catenin mutations as expected. Other relevant molecular alterations associated with risk of neoplastic progression and/or bleeding were detected in 25% of HCAs with the non-high-risk IHC phenotype, suggesting the value of molecular testing in this subset.

Abstract Aims Activating transcription factor 4 (ATF4) functions as a transcriptional regulator in various cell types and tissues under both physiological and pathological conditions. While previous studies have linked ATF4 activation with promoting cardiomyocyte (CM) death in dilated cardiomyopathy (DCM), atrial fibrillation, and heart failure, its role in developing CMs remains unexplored. Methods and results We generated multiple distinct CM-specific (Atf4cKO(e2/3/pA) and Atf4cKO(e2)) and global Atf4 knockout (KO; Atf47del/7del and Atf41ins/1ins) mouse models targeting different Atf4 regions, as well as CM-specific deletion of Rps19bp1 to study cardiac phenotypes. Detailed morphological and molecular analyses were performed. Atf4cKO(e2/3/pA) [targeting exon 2–3 including the polyadenylation signal (polyA)] mice exhibited severe cardiac defects and died before E17.5, likely due to ectopic activation of the p53 signaling pathway resulting from Rps19bp1 downregulation, a potent suppressor of p53. Further investigation revealed that deleting the polyA signal of Atf4 in Atf4cKO(e2/3/pA) mice led to transcriptional readthrough, resulting in the formation of an Atf4-Cacna1i fusion transcript and Rps19bp1 downregulation. To avoid readthrough while abolishing ATF4 function, we introduced small indels into exon 3 of Atf4 in mice (Atf47del/7del and Atf41ins/1ins), which showed normal Rps19bp1 expression and cardiac morphology. Importantly, CM-specific deletion of Rps19bp1 recapitulated the cardiac defects and transcriptional change seen in Atf4cKO(e2/3/pA) mice. Conclusion We found that the downregulation of Rps19bp1, not the loss of ATF4 function, underlies the cardiac phenotypes in Atf4cKO(e2/3/pA) mice. The reduced expression of Rps19bp1 in Atf4cKO(e2/3/pA) mice is likely due to the unintentional deletion of Atf4 polyA signal and subsequent transcriptional readthrough, underscoring the essential role of RPS19BP1, not ATF4, in cardiac development. Consistent Rps19bp1 downregulation has been observed in other tissue-specific Atf4 KO models utilizing the Atf4fl(e2/3/pA) allele, suggesting that previously reported Atf4 KO phenotypes may result from Atf4 transcriptional readthrough effects. These findings reveal a locus-dependent transcriptional interference mechanism and emphasize the importance of avoiding confounding cis effects in genetically engineered models.

Malignant glioma is considered invariably recalcitrant, thus necessitating development of new therapeutic approaches. Spontaneously arising canine glioma exhibits important molecular and pathological similarities to malignant pediatric glioma, making it an invaluable model for testing novel therapies. We evaluated safety and activity of RNA lipid particle aggregates (LPAs) designed to provoke cancer immunogenicity in 10 dogs with histologically confirmed glioma. Vaccine manufacturing was feasible in all subjects and generally well tolerated. Median survival time was 123 and 155 days in dogs receiving three (Group A) or four (Group B) vaccines, respectively; this was increased from historical reporting of subjects receiving palliative care. Responding animals had a robust cytokine response following infusions. In animals receiving non-specific RNA-LPAs, there was localization of messenger RNA (mRNA) payloads to the brain tumor microenvironment and a rapid shift in immunologic gene signatures consistent with a viral response. These data demonstrate the ability to induce rapid viremic response in the tumor microenvironment following a single peripherally administered mRNA vaccine. Since RNA-LPAs are amenable to repeat boosts, these formulations may overcome challenges of tumor immunosuppression and therapeutic access and are currently under evaluation in first-in-human trials ( NCT04573140 , NCT06389591 ).

Abstract The brain avidly consumes glucose to fuel neurophysiology. Cancers of the brain, such as glioblastoma (GBM), relinquish physiological integrity and gain the ability to proliferate and invade healthy tissue. How brain cancers rewire glucose utilization to drive aggressive growth remains elusive. Here, we infused 13C-labeled glucose into patients and mice with brain cancer, coupled with quantitative metabolic flux analysis, to map the fates of glucose-derived carbon in tumor vs. cortex. Through the first direct and comprehensive measurements of carbon and nitrogen labeling in both cortex and glioma tissues, we uncover profound metabolic transformations. In human cortex, glucose carbons fuel essential physiologic processes including TCA cycle oxidation and neurotransmitter synthesis. Conversely, gliomas downregulate these processes and scavenge alternative carbon sources such as amino acids from the environment, repurposing glucose-derived carbons to generate molecules needed for proliferation and invasion. Targeting this metabolic rewiring in mice through dietary amino acid modulation selectively alters GBM metabolism, slows tumor growth, and augments the efficacy of standard-of-care treatments. These findings illuminate how aggressive brain tumors exploit glucose to suppress normal physiological activity in favor of malignant expansion and offer potential therapeutic strategies to enhance treatment outcomes.

Abstract INTRODUCTION Glioblastoma is the most common malignant adult brain tumor with poor prognosis, largely due to its heterogeneous landscape. The AI-RANO and RANO-RGP groups organized the BraTS-Pathology 2024 challenge, providing a publicly-available dataset and a benchmarking environment for AI models to automatically identify six clinically-relevant histopathologic sub-regions in H&E-stained whole slide images (WSIs). METHODS We reclassified the TCGA-GBM and TCGA-LGG data according to the WHO 2021 criteria and identified diagnostic WSIs of 188 glioblastoma (IDH-wt, CNS WHO Gr.4) patients. A well-defined annotation protocol was communicated to eight neuropathologists, across eight institutions, who created “ground truth” annotations for Cellular Tumor (CT), Geographic Necrosis, Cortical Infiltration, Pseudopalisading Necrosis (PN), Microvascular Proliferation, and Penetration into White Matter (PWM). Comprehensive WSI curation for elimination of artifactual content and follow up partitioning resulted in approximately 300,000 data samples/patches. FINDINGS Inter-observer variability assessment highlighted difficulties in establishing a “gold standard”. The least annotated sub-regions (PWM and PN) were the most challenging to the participating methods, whereas all methods achieved their highest accuracy in the most annotated sub-region (CT). The highest average performance across sub-regions was obtained by a foundation model-based method. However, this top-ranked solution achieved an F1 score of 0.51 (Accuracy=0.65, Sensitivity=0.56, Specificity=0.93). CONCLUSIONS Our findings suggest that achieving state-of-the-art performance, in automatically identifying clinically-relevant glioblastoma sub-regions, remains an unsolved research problem. Analysis of the ground-truth annotations underscores the critical need for more precisely defined and neuropathologically standardized annotation protocol. Current AI algorithms are facing difficulties in addressing glioblastoma’s heterogeneous histologic landscape in the absence of large, comprehensively, and consistently annotated data. Building upon these findings, and towards developing more accurate AI algorithms, the 2025 iteration of the BraTS-Path challenge is currently on-going by leveraging two million data samples, aiming to enhance our disease understanding and improve diagnostic accuracy, ultimately contributing to improved patient outcomes.