Citations

Abstract Introduction Germinal center (GC) formation in lymph node (LN) follicles is essential for generating high-affinity antibodies following infection or vaccination. This response in aging is impaired, resulting in smaller and fewer GCs that generate less abundant antibodies with reduced antigen affinities as compared to young adults. Early GC formation depends on dendritic cell (DC)-mediated activation of naïve CD4+ T cells, which differentiate into CD4+ T follicular helper (TFH) cells that drive B cell responses. Antigen-specific TFH induction is mediated by type 2 conventional DCs, which localize to the T:B cell interfollicular boundaries. Live-cell 2-photon microscopy has previously revealed that T cell priming by DCs occurs in distinct phases of lasting versus intermittent interactions, though the quality and duration of DC:CD4+ T cell interactions has not been characterized in aged hosts. We hypothesize that age-associated alterations in LN microenvironments disrupt these interactions, leading to impaired GC formation. Methods Young and aged mice were subcutaneously immunized in the flank with nitrophenyl hapten conjugated to ovalbumin in alum adjuvant, and naïve OT-II CD4+ T cells were adoptively transferred via retroorbital injection. 48 hours after immunization, draining LNs and naïve controls were analyzed by multiplex immunofluorescence microscopy to map the spatial organization of DCs and stromal elements. Results Structural mapping showed disrupted alignment of stromal networks, suggesting impaired spatial compartmentalization of the aged microenvironment. Moreover, within aged immunized mice the localization of DCs within the interfollicular region and T:B cell zone borders of the LNs were altered. Conclusion Our findings suggest age-associated disruption of the LN microarchitecture diminishes the quality of DC:CD4+ T cell interactions essential for initiating GCs. These insights highlight tissue microenvironmental remodeling as a key contributor to age-related immune decline. Funding Source NIH Topic Categories Lymphocyte Differentiation and Peripheral Maintenance (LYM)

Abstract Introduction Immunotherapy approaches against glioblastoma (GBM) such as immune checkpoint inhibitors (ICI), dendritic cell vaccination, and CAR-T have failed to durably cure most patients. Studies analyzing tumors from ICI responders show that abundance of CD4 and CD8 T cells prior to initiation of therapy predicts responsiveness. Thus, targeting the microenvironment to promote CD4 activity may synergize with ICI. The glioblastoma microenvironment contains high proportions of monocyte-derived macrophages which have potent immunosuppressive capabilities. Characterizing and targeting these immunosuppressive programs is a promising strategy for designing effective combination immunotherapies for glioblastoma patients. Methods We analyzed human glioblastoma snRNAseq datasets to find signaling receptors associated with myeloid immunosuppression and employed murine models of glioblastoma for functional validation. Results By analyzing patient-derived -omics datasets, we identified an understudied TNF-superfamily receptor, Fn14, as being upregulated in glioblastoma-associated myeloid cells with immunosuppressive gene signatures. Using in vitro approaches, we found that Fn14 activation in the tumor microenvironment can drive cytokines implicated in GBM immunosuppression such as IL6, IL1B, and IL8. Thus, Fn14 may serve as a surface marker for microenvironment-remodeling myeloid cells recruited to the tumor from peripheral circulation. Furthermore, in murine models of glioblastoma, we discovered Fn14 KO among glioblastoma-associated myeloid cells increases conventional dendritic cell type 1 (cDC1) and Th1 CD4+ T cell abundance in the tumor microenvironment and significantly prolongs survival. Conclusion These results suggest that blocking Fn14 in glioblastoma-associated myeloid cells can enhance Th1 immunity. Thus, Fn14 may represent a promising dual therapy target. Funding Source NIH Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

Background: Total kidney volume (TKV), a prognostic biomarker in ADPKD, is used to stratify high risk individuals. eGFR measures may carry significant error in ADPKD compared to measured GFR(mGFR). This retrospective study investigates the association between height adjusted TKV (htTKV) and eGFR derived from race-free CKD-EPI equations utilizing creatinine and cystatin C. Methods: eGFR was calculated using 3 race-free CKD-EPI formulas: creatinine-based (CKD-EPI creatinine), cystatin C (CKD-EPI cys), and creatinine-cystatin C (CKD-EPI creatinine-cystatin C) equations on 697 Mayo Clinic ADPKD patients. Correlations between eGFR and TKV measures were estimated and stratified by MIC class risk groups and CKD. Linear regression models were computed to predict ln(htTKV) from the 3 eGFR data sets. The eGFR measures were compared to iothalamate-based mGFR in a subset of patients (n=50). Results: A correlation between eGFR measures and htTKV (Pearson correlation r of -0.53 to -0.54), varied by MIC stratification. Pearson correlation was -0.47 to -0.48 for MIC 1A and 1B, -0.67 to -0.71 for MIC 1C, and -0.67 to -0.68 for MIC 1D and 1E. All equations were significantly associated with htTKV levels, with similar adjusted beta values (95% CI) of -0.15 (-0.17 to -0.13), -0.14 (-0.16 to -0.12), -0.15 (-0.16 to -0.13), for CKD-EPI creatinine, CKD-EPI cystatin C, and CKD-EPI creatinine-cystatin C, respectively. Compared to mGFR, the CKD-EPI creatinine-cystatin C equation was the least biased (mean -0.86 (95% CI: -3.09 to 1.37)) versus CKD-EPI creatinine (2.31 (-0.73 to 5.34)) or CKD-EPI cystatin C (-3.54 (-5.86 to -1.21)), and most precise, with 1-P30 of 16% (95% CI 7.2% to 29.1%), compared to 18% (8.6% to 31.4%) for CKD-EPI creatinine, or 20% (10.0% to 33.7%) for CKD-EPI cystatin C. Conclusion: A moderate correlation between eGFR and htTKV associated with MIC stratification. Associations between htTKV and all 3 CKD-EPI equations were similar. CKDEPIcrcys tended to be the least biased and most precise equation when compared to mGFR and may be a reasonable alternative.

Background: Itraconazole is the preferred antifungal agent for mild to moderate histoplasmosis and step-down therapy following amphotericin B treatment. Although hydroxy-itraconazole, a major metabolite of itraconazole, displays antifungal activity comparable with that of the parent compound, its role in therapeutic drug monitoring targets for histoplasmosis remains uncertain. Methods: The objective was to compare clinical outcomes and adverse events using itraconazole parent-compound concentrations alone versus combined itraconazole and hydroxy-itraconazole concentrations in patients treated for histoplasmosis. This retrospective cohort study included adults with probable or proven histoplasmosis who received itraconazole and had at least 1 documented serum concentration. The primary outcome was clinical response across 3 groups: (1) parent (itraconazole parent-compound concentration >1.0 mcg/mL), (2) combined (parent-compound concentration <1.0 mcg/mL with combined itraconazole plus hydroxy-itraconazole >1.0 mcg/mL), and (3) subtherapeutic (failure to reach either threshold). Treatment response and adverse events were analyzed using the Fisher exact test. Results: Among 108 patients (parent, n = 40; combined, n = 40; subtherapeutic, n = 28), response rates differed across groups (parent (95%); combined (90%); subtherapeutic (67.9%); P = 0.006). There was no difference between the parent and combined groups. Adverse events did not differ, although drug discontinuation occurred more frequently in the subtherapeutic group (parent (5%); combined (20%); subtherapeutic (25%); P = 0.04). Conclusions: Patients who failed to achieve either an itraconazole concentration >1 mcg/mL or a combined itraconazole plus hydroxy-itraconazole concentration >1 mcg/mL had lower response rates. Similar outcomes among patients achieving the itraconazole target alone and those achieving the combined target suggest that hydroxy-itraconazole concentrations may contribute to therapeutic drug monitoring targets in histoplasmosis.

Abstract Introduction The underlying immunopathogenesis of inflammatory arthritis (IA) immune-related adverse event (irAE) remains obscure. Unlike rheumatoid arthritis (RA), where autoantibodies and B cell dysfunction are central features, the contribution of humoral immunity to IA-irAE is unclear. Methods Here, we performed immunophenotyping of peripheral blood from IA-irAE patients, and compared them with seronegative RA patients, ICI-treated patients without irAE, and healthy controls. Results IA-irAE was marked with increased cytotoxic gene expression and metabolic activation in T cells, and reduced CXCR3 and CCR6 expression in CD4+ T cells. Contrary to seronegative RA, IA-irAE patients displayed no significant elevation in autoantibody levels or atypical CD11c+CD21⁻ B cells. IA-irAE was further characterized by elevated levels of IL-6, IL-12, and type I IFN, which correlated with the T cell activation phenotypes. Conclusion Altogether, our findings define IA-irAE as a disease with certain immunological features distinctive from RA, representing a potentially T cell driven, autoantibody-independent autoimmunity. These results offer insights into immune tolerance breakdown and therapeutic targeting in irAEs. Funding Source National Institute of Arthritis and Musculoskeletal and Skin Diseases Mark E. and Mary A. Davis Initiative in Rheumatoid Arthritis Research Mayo Foundation for Medical Education and Research Topic Categories Basic Autoimmunity (BA)

Abstract Introduction Colony stimulating factor 1 receptor (CSF1R)-related leukoencephalopathy is an early onset neurodegenerative disease characterized by microglial deficits, abnormal glial responses, white matter pathology, and severe motor and cognitive decline. Methods At 8 months, mice lacking two copies of the Csf1r gene Fms-intronic regulatory element (FIRE) recapitulate some of the brain pathological features of CSF1R-related leukoencephalopathy, namely the deficits in microglia, astrogliosis, and demyelination. Of note, we detected deficits in lymphatic vasculature and altered macrophage activation in the meninges of Csf1rΔFIRE/ΔFIRE mice by flow, prior to the appearance of brain gliosis, neuronal dystrophy, and fine motor impairment. Results Eliminating the remainder CSF1R-expressing innate immune cells, including border-associated macrophages (BAMs), with PLX5622 at 2 months reshaped the immune crosstalk at the meningeal dura and restored lymphatic vascular expansion in Csf1rΔFIRE/ΔFIRE mice Conclusion Ongoing experiments in the lab will clarify the exact mechanisms through which dysfunctional innate immunity at the brain-meningeal interface and lack of meningeal lymphatic vasculature contribute to the development of brain pathology and impaired motor behavior in this model of CSF1R-related leukoencephalopathy. This work has unveiled novel molecular insights involving the meningeal lymphatic system that might be of therapeutic relevance to canonical central nervous system white matter diseases. Funding Source n/a 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)

Polycystic kidney disease (PKD) arises from mutations in cilia-associated genes, such as PKD1 and PKD2 , expressed in renal epithelial cells, leading to progressive kidney dysfunction and end-stage kidney disease (ESKD). PKD patients exhibit significant heterogeneity in disease progression, largely due to genetic and environmental modifiers. Like patients, mouse models of PKD also exhibit significant heterogeneity with regards to the gene mutated, age of disease onset, and rate of disease progression. To elucidate the cellular and molecular consequences of these variables, we constructed an integrated single-cell RNA sequencing atlas across mouse models of PKD, mapping changes in cell type composition, gene expression, and intercellular signaling networks across the whole atlas and within individual models. Across models, single cell RNA sequencing (scRNAseq) data revealed increased Spp1 (osteopontin) expression and signaling from PKD-enriched clusters. Global deletion of Spp1 in Pkd1 RC/RC mice resulted in a modest reduction in cyst severity and improved kidney function. From these studies, we created a freely available, searchable website (https://bmblx.bmi.osumc.edu/scPKD/) that can be used to identify cross- and intra-model changes in gene expression, guiding researchers to new therapeutic targets for treating PKD.

Progranulin (PGRN) deficiency is a common hallmark in frontotemporal dementia (FTD) patients with granulin ( GRN ) mutations (FTD- GRN ). Previous studies by our group and others have observed that reduced PGRN perturbs lysosomal function and microglial activation, which is believed to accelerate neurodegeneration in FTD- GRN patients. Lysosomal function is intrinsically linked to lipid metabolism, and evidence suggests that GRN deficiency can alter lipid profiles in the brain. Unfortunately, studies to date have focused on whole brain or cortical extracts, limiting our ability to assess cell type-dependent changes in lipid metabolism under disease conditions. Here, we employed lipidomic analysis specifically within the pontine microglia of Grn knock-out (KO) mice, a cell population that was previously linked to disease phenotypes in this model. We observed a significant reduction in the endolysosomal lipid bis(monoacylglycero)phosphate (BMP) and the lipid metabolite phosphatidylethanolamine (PE); these microglial-specific lipid alterations mirror previous whole-brain findings, suggesting that similar changes may occur across multiple cell types in the brain. We also detected a significant increase in the myelin-composing factor galactosylceramide (GalCer), which may reflect an aberrant accumulation of myelin debris within microglia that arises due to defective lysosomal clearance. Notably, lipid perturbations were exacerbated with age within Grn KO microglia, suggesting that changes in lipid metabolism are both age- and genotype-dependent in this model. Together, our results support our hypothesis that PGRN acts as a master regulator of critical microglial processes – including lysosomal function, lipid metabolism, and the regulation of myelination – in an age-dependent manner.

Abstract Introduction: Next generation of Theranostics studies are looking at novel combinations with radiation sensitizers to enhance PRRT’s efficacy. Here, we present safety and efficacy data from a multi-center phase 1 study of a [¹⁷⁷Lu]lutetium-dotatate -triapine combination in patients with GEP-NETs. Methods: The study consisted of two phases (dose escalation and expansion) administering the recommended phase 2 doses (RP2D) for the two agents. All patients received 200 mCi of [¹⁷⁷Lu]lutetium-dotatate on day 1 of four 8-week cycles, in combination with oral triapine administered at assigned dose levels (100 mg, 150 mg or 200mg) from days 1 to 14 of each cycle. Results: A total of 31 (A: 15 ; B: 16 ) patients received treatment. Nine patients experienced dose-limiting toxicities; Grade 3 anemia (n=1), Grade 5 cardiac arrest (n=1), and Grade 4 neutropenia (n=7). Based on the overall safety and pharmacokinetics data, a [¹⁷⁷Lu]lutetium-dotatate (200 mCi) plus triapine (150 mg) dose was selected as the RP2D for the expansion phase. Grade ≥3 treatment related adverse events were observed in 77% patients: anemia (23%), nausea and vomiting (3% ), lymphopenia ( 58%), neutropenia ( 35%) and leukopenia ( 39%). The majority of cytopenias were transient and resolved within two weeks. Among the 28 evaluable patients, the objective response rate (ORR) was 21.4% and the median progression-free survival (mPFS) has not been reached (median follow-up period: 23.7 months). Conclusions: The combination of [¹⁷⁷Lu]lutetium-dotatate (200 mCi) and oral triapine (150 mg D1-14) was well tolerated and demonstrated preliminary activity in patients with well-differentiated GEP-NETs. (NCT04234568).