Citations

Abstract Introduction T cell activation is a dynamic process governed by the strength and duration of antigen recognition via the T cell receptor (TCR). The timing of in vivo TCR signaling— when and how strongly memory CD8+ T cells become reactivated in the inflamed brain following antigen exposure— is a fundamental mechanism that remains unclear. The Nr4a3-Tocky reporter (Tocky) mouse employs a fluorescent timer that shifts from blue to red after TCR-driven Nr4a3 activation, which allows researchers to track activation kinetics through two parameters: the Timer Angle (recency of T cell activation), and the Timer Intensity (strength of signaling). Methods To understand CD8+ T cell activation during this neuroinflammation, we generated memory CD8+ T cells by intracranial Theiler’s murine encephalomyelitis virus infection of these Tocky mice. After viral clearance, we reactivated memory CD8+ T cells by intravenously injecting their cognate antigen. Tissues were collected 0-72 hours post-injection and profiled by flow cytometry. An R pipeline was constructed to transform event-level flow data to quantify the TCR activation. Data were analyzed with a Metropolis—Hastings MCMC algorithm to model activation dynamics and estimate probabilistic transitions between biologically defined states (newly activated, persistent, arrested states). Results These empirical transition probabilities enabled Bayesian comparison of antigen-specific versus nonspecific CD8+ T cells. It was revealed that antigen-specific CD8+ T cells rapidly transition to a high-intensity activation state within 24 hours and maintain persistent signaling compared to nonspecific populations. Conclusion This establishes a biologically grounded, in vivo framework for modeling and comparing TCR signaling during neuroinflammation. Funding Source R01 - NS103212 Topic Categories Neuroimmunology (NEUR)

Abstract Introduction Glioblastoma (GBM) is the most aggressive primary brain tumor in adults with an incident rate of 12,000 cases in the United States every year. Current treatment options for these patients include surgical resection, radiation, and chemotherapy. Despite these conventional treatments, patients have a dismal prognosis mostly due to the inability to deliver therapeutic agents across the blood-brain barrier. In recent years, the use of oncolytic picornavirus has been employed as a novel virotherapy for GBM. We hypothesized that we could enhance antibody delivery to the brain through harnessing the immune response associated with this oncolytic virus. Prior work from our lab has shown that CD8 T cell engagement with MHC class I on brain endothelium induces CNS vascular permeability which is dependent on perforin. We therefore asked if picornavirus antigen specific CD8 T cells could enhance antibody delivery to the brain. Methods To test this, we evaluated the potential of activating MHC class I restricted CD8 T cells in vivo through intravenous administration of their cognate picornavirus antigens. Results We determined that this approach enhanced delivery of antibody to brain parenchyma. Importantly, antibody delivery to the brain was still enhanced when CD8 T cells lacked perforin expression which significantly reduced the toxicity of this combination approach. Conclusion These findings demonstrate that theCD8 T cell response towards virotherapy can be harnessed to promote delivery of therapeutic antibody to the brain. Funding Source NCI — R01 CA 94953 NINDS — R01 NS122174 NINDS —R01 NS103212 Mayo Clinic Graduate School of Biomedical sciences Topic Categories Tumor Immunology: Checkpoints, Prevention, and Treatment (TIPT)

Abstract Introduction CD8 T cells are key immune cells in viral clearance, targeting infected cells following recognition of MHC class I restricted antigen presentation. Previous work has determined that microglia and perivascular macrophages are essential for normal CD8 T cell responses against neurotropic viral infection, indicating that cells at the neurovascular unit can act as antigen-presenting cells. However, the specific importance of microglia MHC class I restricted antigen presentation to brain-infiltrating CD8 T cells has been difficult to define. Methods To address this question, our laboratory generated novel single MHC Class I conditional knockout mice in which H-2Kb or H-2Db can be deactivated specifically in Tmem119+ microglia with tamoxifen administration. Recombinant Theiler’s murine encephalomyelitis virus (TMEV) encoding the model OVA antigen enabled analysis of virus antigen-specific CD8 T cells restricted to H-2Kb class I molecules while Daniel’s strain TMEV H-2Db class I molecules enabled analysis of Db:VP2 specific CD8 T cells. Results Our results revealed profound differences in the response of CD8 T cells upon deletion of MHC class I molecules on microglia. Conditional knockout of H-2Kb in Tmem119+ microglia reduced Kb:OVA epitope specific CD8 T cells in the brain compared to Cre negative littermate controls, and BrdU staining revealed differences in T cell proliferation. Meanwhile, mice with deletion of Db in Tmem119+ microglia had reduced levels of perforin in Db:VP2 CD8 T cells. Furthermore, in a model of CNS vascular disease, the deletion of H-2Db of Tmem119+ microglia reduced CD8 T cell numbers in the brain, as well as the blood-brain barrier (BBB) breakdown observed by a FITC albumin assay. Conclusion These findings demonstrate discrete roles for specific MHC Class I molecules on microglia during CNS viral infection. This data will further our understanding of brain infiltrating CD8 T cell responses in neurologic diseases as well as the regulation of BBB by microglia. Funding Source R01 NS 103212 R01 NS122174 Topic Categories Neuroimmunology (NEUR)

Abstract Introduction The anatomical locations of generating adaptive immune responses to neurotropic viruses are still being investigated. Skull bone marrow (BM) has recently been identified as a pivotal immune site that can sense and respond to a local insult in the brain. Yet, there is a lack of understanding of the role of skull BM during viral encephalitis. We hypothesized that the skull BM is an important niche for antiviral CD8 T cells priming, expansion, and maintenance during Theiler’s murine encephalomyelitis virus infection. Methods Using peptide:MHC tetramer analysis, we determined that antiviral CD8 T cells are primed in the skull BM in early infection, at time points comparable to cervical lymph nodes. Employing MHC class I conditional knockout mice generated by our research group, we inactivated H-2Kb and H-2Db class I molecules on discrete antigen-presenting cell types. Results We determined using these transgenic mice that viral antigen presentation on dendritic cells (DCs) and endothelial cells is essential for the generation of virus-specific T cells in skull BM during acute viral encephalitis. However, antigen presentation by DCs is not required for long-lived antiviral CD8 T cells that reside in skull BM. Moreover, the use of FTY720 to block lymphocyte migration diminished skull antiviral CD8 T cell numbers, suggesting that peripheral trafficking is required for generating skull antiviral CD8 T cells. Conclusion We present compelling evidence for the importance of skull BM as a responsive site that is highly suitable for rapid generation of antiviral CD8 T cells during acute viral encephalitis. Skull BM also serves as a reservoir for memory T cells, long after the resolution of a neurotropic virus infection. This work sheds light on the skull as a potential target for further modulation of the immune response to viral infections in the brain. Funding Source NIH grants R01 NS5103212 and RF1 NS122174 Topic Categories Viral Immunology (VIR)

Abstract Understanding how immune checkpoint inhibitors (ICIs) reshape human T-cell responses requires models that move beyond static transcriptomic snapshots and discrete cell-state classifications. Here, we present an integrative AI-enabled virtual cell framework that represents human CD8⁺ T-cell responses as dynamic and computable systems during ICI therapy. By integrating single-cell RNA sequencing with paired T-cell receptor sequencing within the C2S-scale foundation model, we construct a virtual representation of individual T cells, in which each cell is encoded by a unique functional identity that captures its transcriptional, signaling, and clonal characteristics. Using this framework, we identify a previously unrecognized dynamic latent effector state of CD8⁺ T cells characterized by intermediate expression of effector genes, distinct signaling activity, and ongoing clonal expansion. Across independent patient cohorts, the virtual cell model consistently indicates that ICI therapy mainly acts by unmasking pre-existing effector potential rather than inducing de novo effector differentiation. Notably, this latent effector population remains transcriptionally restrained despite active signaling and clonal expansion, revealing a hidden reservoir of antitumor immune capacity. More broadly, our study demonstrates how AI-enabled virtual cell modeling can reconstruct latent cellular states and their dynamic transitions from multidimensional single-cell data. By incorporating functional identity into virtual cell model, this framework uncovers biologically meaningful yet non-obvious T-cell effector program during cancer immunotherapy and provides a generalizable approach for studying immune dynamics in human disease.

BACKGROUND Medication-refractory essential tremor (ET) patients who undergo MR-guided focused ultrasound or Gamma Knife thalamotomy may experience tremor recurrence, prompting rescue deep brain stimulation (DBS). Yet, the impact of prior ventral intermediate nucleus (VIM) lesioning on DBS targeting, microelectrode recording (MER), and stimulation programming remains uncertain. OBSERVATIONS The authors present 3 ET patients undergoing bilateral DBS for tremor recurrence after thalamotomy. Thalamotomy lesions showed depressed electrophysiological activity versus nonlesioned VIM on MER (p = 0.0397) and required smaller DBS charge density increases for tremor control, suggesting irreversible lesion effects despite tremor recurrence. Tremor recurrence correlated with lesion mislocation; specifically, ablations missed the central VIM (mean 1.8 mm) and decussating dentato-rubro-thalamic tract. For rescue DBS, ventral VIM stimulation yields the greatest tremor reduction, while central VIM stimulation balanced tremor control with adverse effects. LESSONS DBS is a safe, effective rescue treatment for failed thalamotomy without needing to retarget the prior lesion site. The authors advocate for prospective studies of initial DBS targeting 2 mm anterior to standard VIM coordinates, reducing intraoperative readjustment for central VIM stimulation; and initial thalamotomy targeting 1 mm anterior and 1.2–1.5 mm superior to standard coordinates for durable tremor control through ablation of both central and ventral VIM. https://thejns.org/doi/10.3171/CASE25955

ABSTRACT Objective Weight loss is frequently considered a cardinal presenting symptom for patients with Zenker diverticulum (ZD). We hypothesized that weight loss in patients with cricopharyngeal muscle dysfunction (CPMD), with or without diverticula, was associated with the length of symptoms and size of diverticulum. Methods Prospective, multicenter observational study of CPMD patients with and without diverticula reporting unintentional weight loss (+WL) or no weight loss (−WL) prior to enrollment in the Prospective Outcomes of Cricopharyngeal Hypertonicity (POuCH) database. Complications and symptom response using a patient reported outcome measure, the Eating Assessment Tool (EAT‐10), were compared. Results Of 427 patients, 101 (23.6%) were +WL. Median weight loss was 14 pounds (interquartile range [IQR] 10–25). +WL cohort had a mean age of 71.5 (standard deviation [SD] 11.5) vs. 67.9 in −WL (SD 11.6, p = 0.007). Mean preoperative EAT‐10 score was 24.7 in +WL (SD 9.7) and 14.8 in −WL (SD 8.8, p < 0.0001). Higher preoperative weight loss was associated with higher preoperative EAT‐10 ( p < 0.0001, Spearman's ρ = 0.43). Size of diverticulum was associated with WL ( p = 0.003), but weight loss was highest in both large diverticula and CP bars. Duration of symptoms was not associated with weight loss ( p = 0.30). Postoperative complications in +WL and −WL patients were similar ( p = 0.78). Conclusion Unintentional weight loss is common with ZD. Patients with worse dysphagia are more likely to have more weight loss. Weight loss does not increase with the size of the diverticulum or length of symptoms. Surgery has a similar safety profile with greater improvement in dysphagia in patients reporting weight loss. Level of Evidence 3.

Abstract: Kimura disease typically presents with painless head and neck swelling in young adults of Asian descent, accompanied by peripheral eosinophilia and elevated serum IgE. We report a case of Kimura disease in a woman in her early 30s presenting with a slowly enlarging epitrochlear mass, diffuse encasement of the median and medial brachial cutaneous nerves, and a concurrent prurigo nodularis-like papular rash affecting all 4 extremities. The diagnosis required over 1 year of investigation and 5 tissue specimens, including 2 nondiagnostic core-needle biopsies, before near total excision was performed. The excision revealed characteristic histopathologic features, including hyperplastic reactive secondary lymphoid follicles with preserved architecture, a marked eosinophilic infiltrate with eosinophilic microabscesses, postcapillary venule proliferation, and patternless stromal fibrosis. Immunohistochemistry demonstrated a raised IgG4:IgG plasma cell ratio of approximately 1:1, with 150–200 IgG4-positive plasma cells per high-power field, raising the differential of IgG4-related disease; however, the absence of storiform fibrosis and obliterative phlebitis, combined with the clinical and serologic profile, favored Kimura disease. This case is notable for its rare epitrochlear location, extensive neural involvement, concurrent diffuse cutaneous eruption, and histopathologic overlap with IgG4-related disease, highlighting the diagnostic challenges posed by atypical presentations of Kimura disease.

Background: Increased posterior tibial slope (PTS) and anterior tibial translation (ATT) result in a higher risk of anterior cruciate ligament reconstruction failure. Accurate measurement of PTS and ATT is essential to guide surgical planning in these patients. Full-length weightbearing lateral tibial radiographs yield the most accurate measurement of PTS and ATT compared with short-film tibial radiographs, computed tomography scans, and magnetic resonance imaging. Indications: We aim to demonstrate a validated, reproducible technique in a stepwise fashion to accurately measure PTS and ATT using full-length weightbearing lateral tibial radiographs. This presentation adds to the field by offering a precise measurement technique for surgical planning purposes. Technique Description: To precisely measure PTS using a full-length weightbearing lateral tibial radiograph, first, perpendicular lines are drawn 5 cm proximal to the ankle joint and 5 cm distal to the knee joint. A line is then extended proximally from the center of the perpendicular line near the ankle through the center of the perpendicular line near the knee, and then extended up to the tibial articular surface. Next, a line is drawn along the medial tibial plateau. The angle measured between these 2 lines is subtracted from 90° to yield the PTS. To precisely measure ATT, a line is drawn along the diaphysis of the tibia and approximated to the posterior aspect of the proximal tibia. Then, another parallel line is drawn and approximated to the posterior aspect of the distal femur. The distance between these lines is measured to yield anterior tibial translation. Results: We measured a PTS of 14.2° and an ATT of 12.6 mm using the technique described in this presentation. Discussion/Conclusion: This technique demonstrates an accurate and reproducible method to precisely measure PTS and ATT using full-length weightbearing lateral tibial radiographs. This technique yields greater accuracy in PTS and ATT than other imaging modalities. As a result, there is a direct benefit for surgical planning when using this technique. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.