Citations

Abstract A promising strategy in tumor immunotherapy is the use of activated dendritic cells as vehicles for tumor vaccines. Clinical trials of dendritic cell-based immunotherapies have proven successful, resulting in recent FDA approval for their use in the treatment of late-stage prostate cancer. Current formulations for dendritic cell-based immunotherapies are capable of prolonging patient survival by only four months, providing motivation for further investigation of ways to enhance dendritic cell priming of anti-tumor T cell responses. Since the discovery of B7-H1 by our laboratory, we have been investigating the regulatory function of B7-H1 expressed by immune cells. In preliminary studies investigating the use of B7-H1 knockout dendritic cells as tumor vaccines, we found that B7-H1 knockout dendritic cells prime enhanced anti-tumor CD8 T cell responses. Further investigations revealed that the enhanced CD8 T cell response raised by B7-H1 knockout dendritic cells is not due to a lack of signaling through the receptors for B7-H1 on CD8 T cells. We observed that B7-H1 knockout dendritic cells produced increased levels of IL-12, a key cytokine that is centrally involved in both innate and adaptive immunity. Our results suggest that B7-H1 expressed by dendritic cells has a role in negatively regulating IL-12 production, and as a result B7-H1 deficient dendritic cells are able to prime enhanced anti-tumor CD8 T cell responses.

Abstract We utilized CD11a, an integrin up-regulated on effector and memory CD8+ T cells, as a biomarker to identify, measure, and monitor endogenous tumor-reactive cytotoxic lymphocytes (CTLs) in two mouse tumor models and in melanoma patients. CD11ahigh CD8+ T cells were detected in primary and metastatic tumor sites after tumor cell injection, as well as in spontaneous murine breast cancer tissues. In the peripheral blood of melanoma patients, tumor antigen-specific T cells were detected within the population of CD11ahigh CD8+ T cells that express high levels of PD-1. Infusion of lethally irradiated tumor cells failed to stimulate the expansion of CD11ahigh CD8+ T cells, suggesting that the access of tumor cells to target tissues is required to induce CD11ahigh CD8+ T cell responses. Phenotypic analysis revealed that the CD11ahigh CD8+ T cells detected in our studies were proliferating (Ki67+) activated T cells (CD62L-, CD69+). Although CD11ahigh CD8+ T cells were differentiated effector cells with CTL effector functions, they were typically unable to control tumor growth in our mouse models, possibly due to high expression of PD-1. Our results demonstrate that CD11a can be used as a biomarker to identify and track endogenous tumor-reactive CTLs.

Abstract Eosinophil infiltration into tumors has been associated with positive and negative growth human cancers and in mouse models of tumorigenesis. Our previous studies have shown that eosinophils infiltrate tumors and differentially accumulate in the necrotic and capsule regions of tumors. Using various eosinophil-deficient mouse models, we demonstrate that in the absence of eosinophils tumor growth is attenuated. Methods: Tumor growth kinetics were assessed using a B16F10 melanoma subcutaneous cell injection model. Eosinophil chemotaxis was assessed using an ex vivo transwell insert assay system. We compared tumor growth in wild type animals vs. various eosinophil-deficient mouse models that are transgenic line of mice (PHIL) and MBP-/-/EPO-/- double knockout mice that are deficient in eosinophil-specific proteins (major basic protein (MBP) and eosinophil peroxide (EPO)) resulting in a blockade of eosinophilpoiesis. Conclusions: The migration of eosinophils was inhibited through blocking the sphingosine-1-phosphate pathway, suggesting recruitment and accumulation is primarily an inflammatory response. Tumor growth was decreased by ~40-60% in PHIL and in MBP-/-/EPO-/- double knockout mice relative to tumors in wild type animals. In addition, EPO-/- mice, and not MBP-/-mice, replicate this ~40% reduction in tumor size implicating a significant role for EPO in tumor growth kinetics. These data suggest eosinophils respond to inflammatory mediators and mediate augment tumor growth.

Abstract Autoimmune uveitis affects 150,000 Americans annually and is a leading cause of blindness. Pathogenesis is thought to involve T cell mediated responses to retinal proteins, such as retinal arrestin (S-Ag). Susceptibility to autoimmune uveitis is strongly associated with HLA class I and class II, but relatively little is known about the nature of HLA class II alleles and about the epitopes that might be pathogenic in the context of different HLA class II molecules. Using a ‘humanized’ mouse model for experimental autoimmune uveitis (EAU) in HLA transgenic mice, we have identified permissive and non-permissive alleles of the HLA-DR and -DQ genes and characterized allele-specific uveitogenic epitopes. The sequences of these epitopes overlap with some of the previously identified peptides of S-Ag (M and N), which elicit memory responses in lymphocytes of uveitis patients. HLA-DR restricted S-Ag specific CD4+ T cells could be detected in blood and draining lymph nodes of immunized mice using HLA class II tetramers, demonstrating the potential use of this reagent to detect and isolate antigen specific T cells in uveitis patients. Our data provide new insights into the pathogenesis of human uveitis, and may help in the development of antigen specific therapies.

Abstract Studies from cancer and chronic infections show that B7-H1 (PD-L1) engagement with its receptor PD-1 enhances apoptosis of effector T cells. It is not clear how B7-H1 regulates T cell apoptosis and the subsequent impact of B7-H1 on T cell memory generation. In immunized B7-H1 deficient mice we observed increased expansion of effector CD8 T cells and delayed T cell contraction followed by protective CD8 T cell memory capable of completely rejecting tumor metastases in lung tissue. Intracellular staining revealed that antigen-primed CD8 T cells in B7-H1 deficient mice express lower levels of the pro-apoptotic molecule Bim. Injection of B7-H1 or PD-1 blocking antibody into immunized mice reduced Bim levels in effector CD8 T cells. In vitro studies show that engagement of activated CD8 T cells by plate-bound B7-H1 fusion protein led to increased cell death and higher levels of Bim expression. Our results suggest that B7-H1 may negatively regulate CD8 T cell memory by enhancing the depletion of effector CD8 T cells through up-regulation of Bim. Our findings would provide a new strategy to target B7-H1 signaling in effector CD8 T cells to achieve protective immunity in the treatment of cancer and infectious diseases.

Abstract Spontaneous antitumor immunity remains challenging to detect and monitor largely due to the absence of established biomarkers. We selected the integrin CD11a as a biomarker to define antitumor T cell responses. CD11a is up-regulated on effector and memory T cells and is involved in the killing of tumor cells by cytotoxic T lymphocytes. In primary (subcutaneously inoculated) and metastatic (intravenously injected) tumors, CD11a high CD8 T cells were detected in the primary (skin) or metastatic (lung) tumor sites, but not in secondary lymphoid organs. Once tumors were established, CD11a high CD8 T cells were identified in tumor draining lymph nodes and peripheral blood. Phenotype analysis revealed that CD11a high CD8 T cells were proliferating (Ki67+) activated T cells (CD62L low, CD69 high, PD-1 high). CD11a high CD8 T cells expressed the transcription factor T-bet but not Foxp3. Live, but not dead, tumor cells, induced expansion of CD11a high CD8 T cells in the lung, suggesting that the access of tumor cells to target tissues is required to induce CD11a high CD8 T cell responses. Our results suggest that CD11a may provide a new T cell biomarker to measure ongoing natural tumor-reactive T cell responses and to predicate the efficacy of tumor immunotherapy.

Abstract Atopic dermatitis and allergic contact dermatitis are two of the most common skin diseases. In both diseases, eosinophils have been suggested as potential contributors of the pathologies linked with these skin conditions. Our goal was to establish a causative relationship between the inflammatory response of chemically induced contact hypersensitivity and eosinophil-mediated activities. Wild type and eosinophil-less PHIL mice were sensitized and challenged with 2,4-dinitrochlorobenzene (DNFB) or alternatively trimellitic anhydride (TMA). Time lapsed videography was used to capture the number of itching events associated with treatment. Immunohistochemistry for eosinophils and nerves was performed to correlate the effect of dermatitis on innervation and eosinophil accumulation in these mice. Our studies showed that in both the DNFB and TMA models a robust eosinophil infiltrate occurred that was accompanied by copious levels of eosinophil degranulation. More importantly, these studies demonstrated that metrics of inflammation (e.g., induced ear swelling (i.e., thickness)) was reduced in PHIL mice relative to wild type. Our observations were also directly correlative with a loss of nerve growth and branching in PHIL mice. These data implicate eosinophils as contributors to the pathologies linked with chemically-induced contact hypersensitivity, including the induced itch responses associated with these models.

Objectives Early in the pandemic, institutional leadership recognised the importance of providing staff with practical, clinically based communication resources. This paper describes the process of cultivating and disseminating rapid communication resources across a multisite institution to assist others who may need to rapidly respond to communication challenges in the future. Methods In April 2020, the Mayo Healthcare Incident Command System charged the Center for Palliative Medicine with developing and disseminating clinical communication resources within several weeks. The Education Chair for the Center for Palliative Medicine created a COVID-19 communication task force composed of clinician-educators with expertise in serious illness communication from all three academic Mayo Clinic sites. The task force elected to focus on providing accessible, just-in-time online content curated from existing resources and adapted to situational needs. Results The task force developed one-page resources with example language on 16 topic areas. Topics included exploring patient values, discussing time-limited trials and making recommendations. The COVID-19 communication website was launched on 28 May, 6 weeks after the institutional request. Conclusions Key takeaway lessons were the need for: (1) alignment with institutional need and priority, (2) rapid team formation with communication education experts across a variety of institutional geographic settings, (3) quick consensus on topic and content delivery to be practically helpful to clinicians, (4) collaboration with outside groups to use and adapt already available resources when possible and (5) early and iterative involvement with information specialists to help facilitate institutional dissemination.

AbstractBackgroundGiven the triplication of chromosome 21 and the location of the amyloid precursor protein gene on chromosome 21, almost all adults with Down syndrome (DS) develop Alzheimer disease (AD)‐like pathology and dementia during their lifetime. Comparing amyloid accumulation in DS to autosomal dominant AD (ADAD), another genetic form of AD, may improve our understanding of early AD pathology development.MethodWe assessed amyloid positron emission tomography (PET) imaging in 192 participants with DS and 33 sibling controls from the Alzheimer’s Biomarker Consortium‐Down Syndrome (ABC‐DS) and 265 mutation‐carriers (MC) and 169 familial controls from the Dominantly Inherited Alzheimer Network (DIAN) (Table 1). We calculated regional standard uptake value ratios (SUVR) using a cerebellar cortex reference region and converted global amyloid burden SUVR to centiloids. We compared amyloid PET by cognitive status and estimated‐years‐to‐symptom‐onset (EYO). EYO was calculated for DIAN participants by subtracting their age from parental age of symptom onset and for ABC‐DS participants by subtracting their age from 50.2 years, a published average age of symptom onset in a large sample of individuals with DS (Fortea et al., 2020). In a subset of participants, we assessed the relationship between amyloid PET and CSF Aβ42/40.ResultThe relationship between CSF Aβ42/40 and amyloid PET was similar in DS and MC participants (Figure 1). We did not observe significant differences between MC and DS grouped by cognitive status (Figure 2). However, when assessed over EYO, global amyloid burden was significantly elevated in MC at EYO ≥ ‐23 but was not elevated in DS until EYO ≥ ‐15 (Figure 3). We observed early cortical and subcortical amyloid PET increases in both groups, but we also measured some regional differences in amyloid PET changes between MC and DS, specifically in the medial occipital region (Figure 4 and 5).ConclusionThese results demonstrate similarities in the relationship between amyloid biomarkers and the levels of amyloid accumulation in ADAD and DS. However, we also observed a 5‐10 year delay and some regional differences in amyloid accumulation in DS. This is important for future clinical trials to consider when recruiting participants and determining treatment efficacy.