Human Immune Cell Populations Research Articles

Abstract 4215: Single-cell proteomic characterization of the tumor microenvironment in humanized NOG-EXL patient-derived xenograft (PDX) models

Abstract Introduction: CD34+ hematopoietic stem cell (HSC) derived humanized mice engineered to express human cytokine transgenes are promising models for the evaluation of novel immunotherapeutic treatments. While flow cytometry-based analyses have confirmed the presence of many human immune cell populations within humanized mice bearing patient-derived tumor xenografts (PDX), comprehensive high-dimensional immunophenotyping of the tumor microenvironment (TME) of these models remains limited. Beyond this, the relative influence of PDX vs. donor CD34+ HSC populations on TME composition is poorly understood. Here, we characterize the quantity and diversity of immune cell subpopulations in the TME, bone marrow, and spleen of humanized NOG-EXL (huNOG-EXL) mice using Cytometry by Time-Of-Flight (CyTOF) data with > 60 features. Methods: We performed CyTOF analysis on 250 dissociated samples from primary tumors (n = 15; n = 6 head and neck cancer, n = 6 ovarian cancer, n = 3 renal cell carcinoma), as well as xenograft (n = 59), spleen (n = 88), and bone marrow (n = 88) samples from huNOG-EXL mice (Taconic). Each sample was profiled with two partially overlapping antibody panels; an innate immunity-focused panel (40 features), and an adaptive immunity-focused panel (40 features). Results: CyTOF data were collected from over 10 million live immune cells for each of the adaptive and innate antibody panels. Unbiased clustering of single-cell marker expression revealed clusters corresponding to all major lymphoid and myeloid cell types. Therapeutically relevant cell states were identified including exhausted CD8+ T cells marked by PD-1 and Tim-3 expression, and PD-L1+ macrophages. Hierarchical clustering of bone marrow and spleen samples suggested that systemically, immune composition was not driven by tumor-intrinsic factors alone with many samples clustering on the basis of CD34+ stem cell donor ID. Conversely, clustering PDX samples revealed strong consistency in xenografts originating from the same primary tumor sample regardless of the chosen stem cell donor. The immune composition of primary tumor samples showed greater similarity with matched PDX samples versus unmatched PDX samples, further supporting that tumor-intrinsic factors drive immune composition in xenografts. Conclusions: We provide a high-resolution characterization of the immune phenotypes present in huNOG-EXL PDX models across three cancer types. These data captured substantial heterogeneity in the immune composition of humanized xenograft samples, and we demonstrate that immune composition in humanized xenografts is strongly driven by tumor-intrinsic features. Overall, this resource data supports the use of these models for immuno-oncology studies with future work focused on functionally validating specific immune cell populations of interest. Citation Format: Daniel Stueckmann, Jalna Meens, Sally Zhang, Shirley Hui, Sujana Sivapatham, Sephane Chevrier, Jennifer Pfeil, Lisa Martin, Maria Komisarenko, Philip Dube, Susan Prendeville, Hartland Jackson, Antonio Finelli, Gary Bader, Bernd Bodenmiller, Keith A. Lawson, Laurie Ailles. Single-cell proteomic characterization of the tumor microenvironment in humanized NOG-EXL patient-derived xenograft (PDX) models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4215.

Interspecies comparison of the early transcriptomic changes associated with hepatitis B virus exposure in human and macaque immune cell populations.

Hepatitis B virus (HBV) infection affects 300 million individuals worldwide, representing a major factor for the development of hepatic complications. Although existing antivirals are effective in suppressing replication, eradication of HBV is not achieved. Therefore, a multi-faceted approach involving antivirals and immunomodulatory agents is required. Non-human primates are widely used in pre-clinical studies due to their close evolutionary relationship to humans. Nonetheless, it is fundamental to identify the differences in immune response between humans and these models. Thus, we performed a transcriptomic characterization and interspecies comparison of the early immune responses to HBV in human and cynomolgus macaques. We characterized early transcriptomic changes in human and cynomolgus B cells, T cells, myeloid and plasmacytoid dendritic cells (pDC) exposed to HBV ex vivo for 2 hours. Differentially-expressed genes were further compared to the profiles of HBV-infected patients using publicly-available single-cell data. HBV induced a wide variety of transcriptional changes in all cell types, with common genes between species representing only a small proportion. In particular, interferon gamma signaling was repressed in human pDCs. At the gene level, interferon gamma inducible protein 16 (IFI16) was upregulated in macaque pDCs, while downregulated in humans. Moreover, IFI16 expression in pDCs from chronic HBV-infected patients anti-paralleled serum HBsAg levels. Our characterization of early transcriptomic changes induced by HBV in humans and cynomolgus macaques represents a useful resource for the identification of shared and divergent host responses, as well as potential immune targets against HBV.

Sialokinin in mosquito saliva shifts human immune responses towards intracellular pathogens.

Mosquito saliva is a mix of numerous proteins that are injected into the skin while the mosquito searches for a blood meal. While mosquito saliva is known to be immunogenic, the salivary components driving these immune responses, as well as the types of immune responses that occur, are not well characterized. We investigated the effects of one potential immunomodulatory mosquito saliva protein, sialokinin, on the human immune response. We used flow cytometry to compare human immune cell populations between humanized mice bitten by sialokinin knockout mosquitoes or injected with sialokinin, and compared them to those bitten by wild-type mosquitoes, unbitten, or saline-injected control mice. Humanized mice received 4 mosquito bites or a single injection, were euthanized after 7 days, and skin, spleen, bone marrow, and blood were harvested for immune cell profiling. Our results show that bites from sialokinin knockout mosquitoes induced monocyte and macrophage populations in the skin, blood, bone marrow, and spleens, and primarily affected CD11c- cell populations. Other increased immune cells included plasmacytoid dendritic cells in the blood, natural killer cells in the skin and blood, and CD4+ T cells in all samples analyzed. Conversely, we observed that mice bitten with sialokinin knockout mosquitoes had decreased NKT cell populations in the skin, and fewer B cells in the blood, spleen, and bone marrow. Taken together, we demonstrated that sialokinin knockout saliva induces elements of a TH1 cellular immune response, suggesting that the sialokinin peptide is inducing a TH2 cellular immune response during wild-type mosquito biting. These findings are an important step towards understanding how mosquito saliva modulates the human immune system and which components of saliva may be critical for arboviral infection. By identifying immunomodulatory salivary proteins, such as sialokinin, we can develop vaccines against mosquito saliva components and direct efforts towards blocking arboviral infections.

Coupling Hematoma Evacuation with Immune Profiling for Analysis of Neuroinflammation After Primary Intracerebral Hemorrhage: A Pilot Study

We sought to explore the use and feasibility of an integrated hematoma evacuation/tissue preservation system coupled with immune profiling to assess human exvivo immune cell populations from brain hematoma samples after intracerebral hemorrhage (ICH). In this nonrandomized, noncontrolled pilot/feasibility study of 7 patients with primary supratentorial ICH, a hematoma evacuation device and integrated tissue preservation system were used to obtain hematoma samples during surgical evacuation. Samples were processed, cryopreserved, and analyzed using flow cytometry to determine the relative distribution of immune cell populations compared with peripheral blood mononuclear cells from healthy control subjects. This study demonstrates proof of concept for an integrated hematoma evacuation and sample preservation system to collect human brain hematoma samples for flow cytometry analysis after acute human ICH. In our preliminary analysis, hematoma samples demonstrated a different makeup of white blood cells than peripheral blood from healthy controls. Flow cytometry analysis of hematoma samples in ICH demonstrates the potential to provide important insights into neuroinflammation associated with ICH.

Study of the effects of Lemna minor extracts on human immune cell populations.

Lemna minor is a plant with a huge repertoire of secondary metabolites. The literature indicates that extracts of Lemna minor have antioxidant, antiradical, immunomodulatory and anti-inflammatory properties. The objective of the present study was to find a suitable technique to extract active compounds from this plant and verify whether these extracts have immunomodulatory activity. We grew L. minor on a standard medium with Gamborg B5 and vitamins. We extracted compounds from the plant by maceration and decoction. The phytochemical profile of the extracts was characterized by chromatography, spectrophotometry, and spectroscopy. The extracts were tested on cultures of mononuclear cells from four human subjects. These cells were pulsed with carboxyfluorescein succinimidyl ester, grown in triplicate in standard culture medium without (control) and with increasing concentrations of Lemna extracts. Flow cytometry was used to evaluate cell death and proliferation of the total mononuclear cell population and of CD4+, CD8+, B cell and monocyte populations. The Lemna extracts were not cytotoxic and did not cause cell necrosis or apoptosis in immune cells. At low concentrations, they induced very limited proliferation of CD4+ cells within 48 hours. At high concentrations, they induced proliferation of CD8+ cells and B lymphocytes within 48 hours. Unfortunately, we failed to confirm any immunomodulatory activity of Lemna extracts. Growth and death rates of human immune cells were not significantly affected by adding Lemna extracts to the culture medium.

Changes in Immune Cell Types with Age in Breast are Consistent with a Decline in Immune Surveillance and Increased Immunosuppression

A majority of breast cancers (BC) are age-related and we seek to determine what cellular and molecular changes occur in breast tissue with age that make women more susceptible to cancer initiation. Immune-epithelial cell interactions are important during mammary gland development and the immune system plays an important role in BC progression. The composition of human immune cell populations is known to change in peripheral blood with age and in breast tissue during BC progression. Less is known about changes in immune populations in normal breast tissue and how their interactions with mammary epithelia change with age. We quantified densities of T cells, B cells, and macrophage subsets in pathologically normal breast tissue from 122 different women who ranged in age from 24 to 74 years old. Donor-matched peripheral blood from a subset of 20 donors was analyzed by flow cytometry. Tissue immune cell densities and localizations relative to the epithelium were quantified in situ with machine learning-based image analyses of multiplex immunohistochemistry-stained tissue sections. In situ results were corroborated with flow cytometry analyses of peri-epithelial immune cells from primary breast tissue preparations and transcriptome analyses of public data from bulk tissue reduction mammoplasties. Proportions of immune cell subsets in breast tissue and donor-matched peripheral blood were not correlated. Density (cells/mm2) of T and B lymphocytes in situ decreased with age. T cells and macrophages preferentially localized near or within epithelial bilayers, rather than the intralobular stroma. M2 macrophage density was higher than M1 macrophage density and this difference was due to higher density of M2 in the intralobular stroma. Transcriptional signature analyses suggested age-dependent decline in adaptive immune cell populations and functions and increased innate immune cell activity. T cells and macrophages are so intimately associated with the epithelia that they are embedded within the bilayer, suggesting an important role for immune-epithelial cell interactions. Age-associated decreased T cell density in peri-epithelial regions, and increased M2 macrophage density in intralobular stroma suggests the emergence of a tissue microenvironment that is simultaneously immune-senescent and immunosuppressive with age.

Abstract 3020: Human leukocyte antigen (HLA) typing of a broad panel of cancer patient-derived xenograft (PDX) models for immune therapies

Abstract Background In immuno-oncology research, an appropriate microenvironment for both human tumor cells and human immune cells is an important but challenging factor for successful development of relevant preclinical models. Humanized patient-derived xenograft (PDX) models can support establishment of such an environment based on matching human leukocyte antigen (HLA) profiles of PDX and compatible human immune cell populations. In this study, we determined the individual HLA types of a broad panel of 291 established PDX models from 18 different tumor entities. Furthermore, we performed comprehensive HLA matching analyses of all PDX models and 13 peripheral blood mononuclear cell (PBMC) donors to enable personalized studies with HLA-matched PDX. Methods The HLA profile of each PDX was determined comprising HLA class I, II and non-class types in 4-digit resolution. Matching analyses were performed according to donor-recipient HLA matching criteria recommended by the Blood and Marrow Transplant Clinical Trials Network (BMT CTN). For comparative HLA profile analyses, allele frequencies of 8862 German stem cell donors provided by The Allele Frequency Net Database were downloaded. Results The individual HLA profiles of all PDX models were generated comprising HLA-A, -B and -C (class I), HLA-DQA1, -DQB1, -DRB1, -DPA1 and -DPB1 (class II) as well as HLA-H (non-class) types. Comparative analyses of HLA profiles revealed that obtained frequencies of PDX HLA alleles are comparable with frequencies of a representative population of 8862 German stem cell donors. HLA profile matching analyses performed for all PDX models and PBMC donors resulted in 15 matches regarding PDX from head and neck, lung, mammary and pancreatic carcinoma as well as from endometrial cancer, glioma, lymphoma, melanoma and sarcoma. Dependence of immune therapy efficacy on matched HLA profiles was shown exemplarily for a head and neck squamous cell cancer (HNSCC) PDX. The HNSCC PDX was humanized with PBMC from 5 donors representing different degrees of HLA matching (33 - 100 %). Treatment with the checkpoint inhibitor Nivolumab caused a more powerful tumor growth inhibition in matched HLA profiles compared to non-matched profiles. This indicated a relation between antitumoral immune therapy effect and HLA matching in preclinical models. Conclusions We generated a comprehensive HLA profile portfolio containing information of a broad panel of PDX models. Matched HLA profiles of PDX models and PBMC donors enable personalized, preclinical immune-oncology studies to support the development of novel therapeutic strategies. Citation Format: Theresia Conrad, Annika Wulf-Goldenberg, Maria Stecklum, Michael Becker, Konrad Klinghammer, Jens Hoffmann. Human leukocyte antigen (HLA) typing of a broad panel of cancer patient-derived xenograft (PDX) models for immune therapies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3020.

Mixed species live biotherapeutic product improves immunological tolerance in food allergy

Abstract The human gut microbiota is central to early-life immune system education, including the establishment of immune tolerance, and thus represents an important target for the development of preventative interventions against food allergy (FA). The composition of the gut microbiota, and specific bacterial members within the microbiota, have been shown to impact allergic disease development in animal models by limiting basophil hematopoiesis, influencing macrophage polarization, and enhancing regulatory T cell activity. With a growing body of evidence showing the gut microbiota is an important environmental factor contributing to FA development comes an opportunity to translate this knowledge into novel approaches for treating and preventing FA. Using a proprietary human gut microbiota consortium, we have developed a mixed species live biotherapeutic product (LBP) to alleviate FA development and severity. We show that this LBP can directly interact with human immune cell populations modulating immune signaling pathways including TGF-beta, FFARs, chemotaxis, and NFkB inhibition. We also demonstrate that supplementation with this LBP can reduce OVA induced oral anaphylactic severity in mice with humanized gut microbiota. This protective effect may be attributed to increased fecal antigen-specific IgA levels and enhanced intestinal TGFb levels. These data describe immunological mechanism of a mixed species LBP that is protective in mouse FA model.

Artificial Microvesicles Isolated from Mesenchymal Stem Cells with IL2 Overexpression Activate CD8+ T-Killers to Kill Triple Negative Breast Cancer Cells

Almost all human cells release extracellular vesicles (EVs) participating in intercellular communication. EVs are rounded structures surrounded by the cytoplasmic membrane, which embody cytoplasmic contents of the parent cells. Since the orientation of surface receptors persists during EV formation, it is EVs that are of interest as a therapeutic tool for cell-free therapy that has targeted delivery. The ideal cell type for the EV production are mesenchymal stem cells (MSCs) as they exhibit a homing behaviour to tumor niches. In this study, human MSCs were isolated from adipose tissue (hADSCs) and genetically modified to overexpress interleukin-2 (IL2) (hADSCs-IL2) or red fluorescent protein (hADSCs-RFP). Extracellular vesicle release from native and genetically modified hADSCs was induced by cytochalasin B treatment. Size and immunophenotype of isolated Cytochalasin B induced microvesicles (CIMVs) were analysed using flow cytometry. To evaluate immunomodulating properties of microvesicles from native (native CIMVs) or genetically modified (CIMVs-IL2) hADSCs, peripheral blood mononuclear cells (PBMCs) were isolated from human peripheral blood and co-cultured with CIMVs (50 μg/ml) for 72 hours. Activation of PBMC populations was determined by flow cytometry using staining with antibodies specific for surface markers of various human immune cell populations. To analyze the antitumor activity of PBMCs after interaction with CIMVs-IL2, activated PBMCs were transferred to triple negative breast cancer cells MDA-MB-231 which were pre-seeded on 16-well xCelligence plate (3 × 103 cells per well) or 6-well plate (5 × 104 cells per well) in 1:3 ratio (tumor cells:PBMCs). Proliferative activity of tumor cells was evaluated using an RTCA xCelligence instrument (ACEA Biosciences, USA) for 72 hours. Tumor cell viability was assessed 24 hours after culturing with PBMCs using the APC Annexin V Apoptosis Detection Kit with PI (#640932, Biolegend, USA) on FACS Aria III flow cytometer (BD, USA). Isolated CIMVs were mostly 50-200 nm in diameter and positive for CD44, CD90 and CD105 MSC surface markers, but CD29 and CD73 levels were significantly decreased. The number of activated T-killers (CD3+CD8+CD4-CD38+HLA-DR+) was significantly increased after incubation with CIMVs-IL2 (205.6 ± 4.5%) compare to native PBMCs (100.0 ± 9%) and PBMCs incubated with native CIMVs (116.7 ± 4.5%) (Fig. 1A). The number Th1 cells was decreased in the sample of PBMCs incubated with CIMVs-IL2 (92.3 ± 1.6%) compared with native PBMCs (100.0 ± 1%) (Fig. 1B), while the number of Th2 cells (109.0 ± 0.1%) was increased compared to native PBMCs (100.0 ± 1%) (Fig. 1C), number of Tregs was unchanged (Fig. 1D). After the addition of PBMCs, activated with CIMVs-IL2, the proliferation of MDA-MB-231 cells has been significantly decreases. Twenty four hours after the addition of CIMVs-IL2-activated PBMCs the proliferation of MDA-MB-231 was decreased 4-fold (to 25.0 ± 5.6%) compared to native MDA-MB-231 (100.0 ± 2.9%) and MDA-MB-231 incubated with native PBMCs (110.8 ± 8.7%) and PBMCs after native CIMVs (103.7 ± 2.4%) (Fig. 1E,G). This decrease in proliferation is likely due to the fact that part of the tumor cells underwent apoptosis and then died which is confirmed by the MDA-MB-231 cell viability after 24 hours of cultivation with PBMCs activated with CIMVs-IL2 (Fig. 1F). The number of healthy MDA-MB-231 cells after 24 hours of cultivation with PBMCs after CIMVs-IL2 was reduced by 35% (46.1 ± 3.7%) compared to native MDA-MB-231 (78.2 ± 2.1%) and MDA-MB-231 incubated with native PBMCs (70.1 ± 2.8%) and PBMCs after native CIMVs (62.1 ± 3.2%). Viable MDA-MB-231 cells in the sample of PBMCs after CIMVs-IL2 continue to proliferate, however their proliferative activity remains reduced (41.2 ± 4.7%) after 72 hours of cultivation compared to native MDA-MB-231 (100.0 ± 21.0%) and MDA-MB-231 incubated with native PBMCs (109.7 ± 2.5%) and PBMCs after native CIMVs (82.5 ± 20.5%) (Fig. 1H). The use of CIMVs-IL2 can be effective in the treatment of triple negative breast cancer, since CIMVs-IL2 are able to activate and stimulate the proliferation of T-killers, which in turn are able to induce apoptosis in breast cancer cells. However, further studies of CIMVs efficiency in animal tumor models are required. This study was supported by the Russian Science Foundation grant 18-74-10044 and the Russian Government Program of Competitive Growth of KFU. Figure Disclosures No relevant conflicts of interest to declare.

Abstract 5625: Evaluation of in vivo anti-tumor response of solid tumors in a novel immune cell-humanized NOD-Prkdcem26Cd52Il2rgem26Cd22/NjuCrl mouse model

Abstract Background: Checkpoint blockade inhibitors targeting PD-1 and CTLA-4 pathways are clinically approved therapies for multiple cancer types. The performance of targeted interventions has been effective, but clinical response rates vary. In vivo models of human immunity in human tumor bearing mice (TBM) is an important tool for studying mechanisms of targeted therapies and developing new and effective treatments. The NCG (NOD-Prkdcem26Cd52Il2rgem26Cd22/NjuCrl), a recently developed triple immunodeficient mouse strain, is a stable host for both human immune cells and tumors for the study of immuno-oncology-based therapeutics. Study Details: We evaluated the anti-tumor effects of immune checkpoint inhibitors (anti-human PD-1, including Pembrolizumab, and CTLA-4) on colon epithelial carcinoma (RKO) and basal lung cell adenocarcinoma (A549) cell lines in a human donor immune cell-humanized NCG/CRL mouse model (HuCD34NCG). In separate studies Charles River humanized NCG (HuCD34NCG) mice were implanted subcutaneously on the flank with either RKO or A549 tumors. Group randomization occurred when the average tumor size reached a volume of ~100mm3 (A549) or 30-60mm3 (RKO). Control mice were treated with isotype control IgG antibodies. RKO TBM were treated with anti-PD-1 antibody alone, while A549 TBM were dosed with anti-PD1-1 and anti-CTLA-4 antibodies independently and in combination therapy. Results: Human immune cell engraftment levels were confirmed in the peripheral blood, spleen and tumor (hCD45, hCD3, hCD4, hCD8, hCD19, NK, myeloid, macrophages; markers vary based on study) of HuCD34NCG humanized mice. Tumor growth kinetics were monitored throughout the study. Inhibition of RKO and A549 tumor growth upon anti-PD-1 monotherapy was significant. Human T-cell infiltration was observed in A549 and RKO tumors with the majority of live T-cells responsive post infiltration. Human cytokines (IFN-γ, IL-2 and TNF-α) were released by tumor-infiltrating total T-cells (CD3+) and subsets (CD4+ and CD8+), as demonstrated by intracellular cytokine staining following PMA/Ionomycin stimulation. Polyfunctional T-cell responses were detected in all treatment groups at study termination. Conclusions: The results from these studies demonstrate significant immunomodulatory anti-tumor response to immune checkpoint inhibitors. The newly developed HuCD34NCG humanized mouse model showed robust and sustained engraftment of human immune cell populations and demonstrated infiltration of T-cells into tissues and tumors making this mouse model ideal for immuno-oncology studies. Citation Format: JENNY ROWE, Christoph Eberle, Elizabeth Reap, Ann Fiore, Anya Avrutskaya, Paula Miliani de Marval, Robert Mihalek, Stephen Festin. Evaluation of in vivo anti-tumor response of solid tumors in a novel immune cell-humanized NOD-Prkdcem26Cd52Il2rgem26Cd22/NjuCrl mouse model [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5625.

Discovery of CD80 and CD86 as recent activation markers on regulatory T cells by protein-RNA single-cell analysis

BackgroundTraditionally, the transcriptomic and proteomic characterisation of CD4+ T cells at the single-cell level has been performed by two largely exclusive types of technologies: single-cell RNA sequencing (scRNA-seq) and antibody-based cytometry. Here, we present a multi-omics approach allowing the simultaneous targeted quantification of mRNA and protein expression in single cells and investigate its performance to dissect the heterogeneity of human immune cell populations.MethodsWe have quantified the single-cell expression of 397 genes at the mRNA level and up to 68 proteins using oligo-conjugated antibodies (AbSeq) in 43,656 primary CD4+ T cells isolated from the blood and 31,907 CD45+ cells isolated from the blood and matched duodenal biopsies. We explored the sensitivity of this targeted scRNA-seq approach to dissect the heterogeneity of human immune cell populations and identify trajectories of functional T cell differentiation.ResultsWe provide a high-resolution map of human primary CD4+ T cells and identify precise trajectories of Th1, Th17 and regulatory T cell (Treg) differentiation in the blood and tissue. The sensitivity provided by this multi-omics approach identified the expression of the B7 molecules CD80 and CD86 on the surface of CD4+ Tregs, and we further demonstrated that B7 expression has the potential to identify recently activated T cells in circulation. Moreover, we identified a rare subset of CCR9+ T cells in the blood with tissue-homing properties and expression of several immune checkpoint molecules, suggestive of a regulatory function.ConclusionsThe transcriptomic and proteomic hybrid technology described in this study provides a cost-effective solution to dissect the heterogeneity of immune cell populations at extremely high resolution. Unexpectedly, CD80 and CD86, normally expressed on antigen-presenting cells, were detected on a subset of activated Tregs, indicating a role for these co-stimulatory molecules in regulating the dynamics of CD4+ T cell responses.

Immune landscape of genetically-engineered murine models of glioma relative to human glioma by single-cell sequencing

Abstract Glioblastoma (GBM) is the most frequent and deadliest primary brain tumor, with a <10% 5-year overall survival rate. Despite promising results in other disease contexts, deployment of immune system-targeted therapies against GBM has not been successful thus far. In this regard, few preclinical models effectively recapitulate the human GBM immune microenvironment, hindering our ability to identify potentially targetable vulnerabilities. In this study, we characterized tumor immune microenvironment of the Qk/trp53/Pten (QPP) triple-knockout mouse model, harboring alterations common in human GBM and found that tumor infiltrates contain a predominantly myeloid cell population of monocytes, macrophages, and resting dendritic cells, with minor populations of T, B, and NK cells. Notable differences between spontaneous QPP tumors and tumors derived by implanting established QPP cell lines included T-cell enrichment and a larger proportion of myeloid-derived suppressive cells (MDSCs) in implanted tumors. Profiles of myeloid cells subtypes in QPP tumors paralleled findings in human GBMs, suggesting that this model effectively recapitulates the complexity of the myeloid-cell compartment and other human GBM immune cell populations.

Circulating Factors in Trauma Plasma Activate Specific Human Immune Cell Subsets

BackgroundTrauma causes tissue injury that results in the release of damage associated molecular patterns (DAMPs) and other mediators at the site of injury and systemically. Such mediators disrupt immune system homeostasis and may activate multicellular immune responses with downstream complications such as the development of infections and sepsis. To characterize these alterations, we used time-of-flight mass cytometry to determine how trauma plasma affects normal peripheral blood mononuclear cell (PBMC) activation to gain insights into the kinetics and nature of trauma-induced circulating factors on human immune cell populations. A better understanding of the components that activate cells in trauma may aid in the discovery of therapeutic targets. MethodsPBMCs from healthy volunteers were cultured with 5% plasma (healthy, trauma-1day, or trauma-3day) or known DAMPs for 24 h. Samples were stained with a broad immunophenotyping CyTOF antibody panel. Multiplex (Luminex) cytokine assays were used to measure differences in multiple cytokine levels in healthy and trauma plasma samples. ResultsPlasma from day 1, but not day 3 trauma patients induced the acute expansion of CD11c+ NK cells and CD73+/CCR7+ CD8 T cell subpopulations. Additionally, trauma plasma did not induce CD4+ T cell expansion but did cause a phenotypic shift towards CD38+/CCR7+ expressing CD4+ T cells. Multiplex analysis of cytokines by Luminex showed increased levels of IL-1RA, IL-6 and IL-15 in trauma-1day plasma. Similar to trauma day 1 plasma, PBMC stimulation with known DAMPs showed activation and expansion of CD11c+ NK cells. ConclusionsWe hypothesized that circulating factors in trauma plasma would induce phenotypic activation of normal human immune cell subsets. Using an unbiased approach, we identified specific changes in immune cell subsets that respond to trauma plasma. Additionally, CD11c+ NK cells expanded in response to DAMPs and LPS, suggesting they may also be responding to similar components in trauma plasma. Collectively, our data demonstrate that the normal PBMC response to trauma plasma involves marked changes in specific subsets of NK and CD8+ T cell populations. Future studies will target the function of these trauma plasma reactive immune cell subsets. These findings have important implications for the field of acute traumatic injuries.

A Novel Class of Bifunctional Immunotherapeutic That Exploit a Universal Antibody Binding Terminus (uABT) to Recruit Endogenous Antibodies to Cells Expressing CD38 Demonstrates Anti-Multiple Myeloma Activity in Vitro and Ex Vivo against Patient Tumor Cells

Background: Antibody recruiting molecules (ARM) are novel, immunotherapeutic bifunctional molecules composed of two active termini connected by a linker. One of the termini binds to a target molecule on a cancer cell. The other terminus, called universal antibody binding terminus (uABT), recruit all endogenous IgG antibodies independent of their antigen binding specificity. As a result, the target cell is "opsonized" by antibodies which then bring the immune effector cells to eliminate the target through various antibody-dependent destruction mechanisms. Kleo Pharmaceuticals has developed a series of CD38-ARM mlecules which target human CD38 highly expressed by multiple myeloma cells. CD38-ARM compounds are able to mediate ADCC without depleting CD38 expressing immune effector cells like existing therapeutic antibodies such as Daratumumab. Methods: Cyclized peptides containing natural and non-natural amino-acid that selectively bind to human CD38 were identified using Peptidream Flexizyme-based, cell free Peptide Discovery Translation System. These peptides were linked to uABT antibody binder via a linker to generate the final CD38-ARM molecules Binding of CD38-ARM was tested by ternary complex formation between CD38 expressing cells, CD38-ARM and labelled human IgG1. To confirm the activity of CD38-ARM, surrogate CD16a binding and signaling assays were performed using the NFAT Promega system. Antibody dependent cellular cytotoxicity (ADCC) assays using purified NK cells from multiple donors with polymorphism variants (V/V, F/F, and V/F) of CD16a were performed to confirm activity. Live cell imaging was utilized to assess the dynamics of NK-RAJI cell interactions mediated by CD38-ARM +/- IgG. We evaluated the ability of compounds to mediate complement dependent cytotoxicity (CDC). We tested the effect of CD38-ARM on human immune cell populations within PBMC and whole bone marrow (WBM) by flow cytometry. Lastly, ex vivo samples from WBM of MM patients at diagnosis or relapse were used to evaluate CD38-ARM anti-tumor activity as well as off-target effects, without the addition of external source of IgG, through multiparametric flow-cytometry (CD45, CD19, CD38, CD138, CD56, CD27, CD8, CD117). Results: The CD38-ARM were shown to have the ability to bind to CD38 with a 7nM affinity and to human IgG1 and IgG2 with affinity of 15nM and 11nM by SPR. Activity of KP compounds was observed in all assays except for CDC. In ternary assay, KP-6 had an apparent EC50 of 16nM while KP-7's EC50 was 6nM. Both KP-6 and 7 had comparable EC50s in the single digit nanamolar range in the NFAT activation assay induced by CD16a binding was confirmed using human IgG to induce, while Daratumumab had an apparent EC50 of 0.04nM. In the ADCC assay, both KP-6 & KP-7 had EC50s of 7 & 6nM respectively, while Daratumumab had an EC50 of 0.1nM. In addition, no NK cell depletion was observed when PBMC were treated with KP compounds, whereas a profound reduction in both percentages and absolute numbers in this cell subset was observed with Daratumumab treatment. Increasing dose of CD38-ARM (range 0.1uM- 25uM) were tested in ex vivo WBM samples from MM patients together with a negative control and Daratumumab. At concentrations of 10uM and 25uM, CD38-ARM induced a significant reduction of MM cells achieving results comparable to those of Daratumumab activity (p >0.05 in both cases), while sparing all other CD38+ normal cells such as NK, T lymphocytes, monocytes and granulocytes, which are always reduced in the presence of Daratumumab. Conclusions: CD38-ARMs are able to kill MM cells by ADCC without depleting CD38 expressing immune cells contrary to existing antibodies such as Daratumumab. CD38-ARMs do not activate complement, which might be involved in the infusion reaction seen with Daratumumab. Most importantly, CD38-ARMs kill multiple myeloma cells ex vivo in patient bone marrow samples as well as plasma cell leukemia in patient blood. Combined with the in vivo efficacy data presented elsewhere, this data establishes the therapeutic potential of CD38-ARM. They also represent the first demonstration of the ARM platform ability to generate therapeutic agents tailored to a specific indication, by varying target binding moiety of the molecule. Disclosures Rossi: Kleo pharmaceuticals: Employment, Equity Ownership. Bunin:Kleo pharmaceuticals: Employment, Equity Ownership. Iben:Kleo Pharmaceuticals: Employment, Equity Ownership. Welsch:Kleo pharmaceuticals: Employment, Equity Ownership. Berbasova:Kleo Pharmaceuticals: Employment, Equity Ownership. Riillo:Kleo Pharmaceuticals: Research Funding. Ohuchi:Peptidream Inc.: Employment. Alvarez:Kleo pharmaceuticals: Employment, Equity Ownership. Kawakami:Peptidream Inc.: Employment. Nagasawa:Peptidream Inc.: Employment. Spiegel:Kleo pharmaceuticals: Equity Ownership. Rastelli:Kleo pharmaceuticals: Employment, Equity Ownership.

Abstract 1057: PDX models of solid cancer express distinct cytokine profiles in humanized mice relating to their tumor infiltrating lymphocyte landscape

Abstract Model selection is one critical step in anti-cancer drug development. In the advent of immune modulatory compounds being part of most of the oncology drug development pipelines, the available preclinical models have to be characterized with respect to those assets. In the current study we analyzed 26 PDX models covering a broad range of solid cancer entities with regard to the phenotypic characteristics in a humanized environment. Well established PDX models from six different entities (breast, colon, renal, pancreatic, NSCL cancer and glioblastoma) were implanted subcutaneously into immune-compromised mice substituted with CD34+ hematopoietic stem cells (hu-mice). Tumor characterization included: tumor growth curves, take rates, human immune cell infiltrates of tumor (=TILs), peripheral blood, spleen and bone marrow (determined by flow cytometry, FC, and IHC) and secretion of human cytokines in murine serum (determined by cytokine array & Luminex based technology). Those data were compared to equivalent data-sets in non-humanized mice. The analysis of TILs revealed a large bandwidth of immune cell infiltration in the respective model ranging from 94% huCD45+ cells (renal cancer RXF 2773) to 3.54% huCD45+ (NSCLC LXFA 1041). Based on the percentage and of huCD4+ cell engraftment and the ratio of their subtypes (memory vs naïve) in untreated tumors the models were grouped into high (=hot), medium and low (=cold) infiltrated tumor models. The infiltration rate was stable across different experiments and specific for one distinct model. IHC analyses confirmed infiltration rates in tumor tissue determined by FC for CD45+, CD4+ and CD8+ cells. Furthermore, the models previously defined as “hot” or “cold” expressed distinct cytokine profiles in serum of tumor bearing mice. Amongst other cytokines, hot tumors secreted high levels of IL-17A, IL-18 BPa, MMP-9, Osteopontin, CD31, TIM-3 and YKL-40. In contrast, levels of GDF-15 and Lipocalin-2 were down regulated in those models compared to their cold counterpart. Of note, neither the amount nor the composition of human immune cell populations in peripheral blood of those mice was suitable to conclude on the amount of TILs in the respective model. Further validation of the cytokine profiles using immune modulating compounds on hot as well as cold PDX models are currently underway. Taken together, the characterization of PDX models with respect to their TIL composition facilitates model selection for innovative drugs in the immune-oncology field. The possibility to discriminate hot vs cold tumors by a minimal-invasive method like serum analysis of cytokine expression profile as potential biomarker will help to characterize the complete PDX collection of more than 500 models but will as well serve as additional read-out in preclinical I-O studies. Citation Format: Eva Oswald, Dorothee Lenhard, Stefanie Schmitt, Anna Edinger, Anne Löhr, Volker Knauff, Anke Behnke, Anne-Lise Peille, Julia Schüler. PDX models of solid cancer express distinct cytokine profiles in humanized mice relating to their tumor infiltrating lymphocyte landscape [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1057.

Abstract B209: Transcriptomic analysis of patient-derived xenografts reveals heterogeneity in human and mouse stroma/immune compartments

Abstract Introduction: Cancers are increasingly recognized as diverse collections of not only genetic diseases but also immune diseases. The heterogeneous tumor microenvironment (TME), including immune components, plays critical roles in tumor growth/progression and response to pharmaceutics, particularly immuno-oncology therapeutics. However, investigating stroma-specific components is rather challenging due to the difficulty in separating stroma from tumor cells, either physically via microdissection or in silico via bioinformatics. Experimental animal models are excellent system to investigate TME1. For example, patient-derived xenograft (PDX), where human and mouse content can readily be separated in silico2, provides a model to study tumor microenvironment, including tumor-stroma interactions. Methods: Whole transcriptome sequencing was performed on subcutaneous PDXs in athymic mice3 and all reads were aligned to human and mouse genomes to discriminate human and mouse content, respectively. Low expressed/less variable genes were removed across the two components. MCP-counter algorithm4 was used to estimate infiltration by various human immune and other stromal cell populations from human gene expression data. The gene expression profiles of 35 cell types from Immunological Genome Consortium (ImmGen)5 were used to create lineage-specific signatures and compute mouse stroma composition by CIBERSORT6. Weighted gene coexpression network analysis (WGCNA)7 was applied on human and mouse gene expression data, respectively, to identify distinct gene modules associated with different biologic functions. Human-mouse gene correlation analysis was performed to construct cross-species expression networks. Results: We have established and profiled ~1800 subcutaneous PDXs, with ~1500 of them whole transcriptome-sequenced (http://crownbio.com/eortc17/stromalposter)8. The average mouse-to-human sequencing read ratio is around 11%, consistent with the previous report2. By deconvolution analysis of human and mouse gene expression data, we identified all types of adaptive and innate immune cells in mouse stroma of these immune-deficient mice. Most surprisingly, a variety of human immune components were also observed in human expression contents. The corresponding fractions vary across cancer subtypes and individual models. The heterogeneity has been also validated by flow cytometry. Distinct coexpressed gene modules from human (50x) and mouse (28x) revealed that human clusters were more correlated to cancer type than mouse clusters, particularly strong in pancreatic, colorectal, and lung cancers. Knowledge-based functional analysis of these gene modules revealed the association of diverse biologic processes. Moreover, cross-species correlation network identified a novel relationship between human and mouse genes over all PDXs and in specific cancers. Conclusions: Both human and mouse stroma/immune composition exists and varies across cancers in subcutaneous PDXs, with each cancer type and each individual model within subtypes, suggesting PDX as a useful experimental model to study TME. Citation Format: Jia Xue, Wubin Qian, Sheng Guo, Jie Cai, Xuesong Ouyang, Henry Qixiang Li. Transcriptomic analysis of patient-derived xenografts reveals heterogeneity in human and mouse stroma/immune compartments [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B209.

Human and Murine Innate Immune Cell Populations Display Common and Distinct Response Patterns during Their In Vitro Interaction with the Pathogenic Mold Aspergillus fumigatus.

Aspergillus fumigatus is the main cause of invasive fungal infections occurring almost exclusively in immunocompromised patients. An improved understanding of the initial innate immune response is key to the development of better diagnostic tools and new treatment options. Mice are commonly used to study immune defense mechanisms during the infection of the mammalian host with A. fumigatus. However, little is known about functional differences between the human and murine immune response against this fungal pathogen. Thus, we performed a comparative functional analysis of human and murine dendritic cells (DCs), macrophages, and polymorphonuclear cells (PMNs) using standardized and reproducible working conditions, laboratory protocols, and readout assays. A. fumigatus did not provoke identical responses in murine and human immune cells but rather initiated relatively specific responses. While human DCs showed a significantly stronger upregulation of their maturation markers and major histocompatibility complex molecules and phagocytosed A. fumigatus more efficiently compared to their murine counterparts, murine PMNs and macrophages exhibited a significantly stronger release of reactive oxygen species after exposure to A. fumigatus. For all studied cell types, human and murine samples differed in their cytokine response to conidia or germ tubes of A. fumigatus. Furthermore, Dectin-1 showed inverse expression patterns on human and murine DCs after fungal stimulation. These specific differences should be carefully considered and highlight potential limitations in the transferability of murine host–pathogen interaction studies.

Exploring Metabolic Configurations of Single Cells within Complex Tissue Microenvironments

Over the past years, plenty of evidence has emerged illustrating how metabolism supports many aspects of cellular function and how metabolic reprogramming can drive cell differentiation and fate. Here, we present a method to assess the metabolic configuration of single cells within their native tissue microenvironment via the visualization and quantification of multiple enzymatic activities measured at saturating substrate conditions combined with subsequent cell type identification. After careful validation of the approach and to demonstrate its potential, we assessed the intracellular metabolic configuration of different human immune cell populations in healthy and tumor colon tissue. Additionally, we analyzed the intercellular metabolic relationship between cancer cells and cancer-associated fibroblasts in a breast cancer tissue array. This study demonstrates that the determination of metabolic configurations in single cells could be a powerful complementary tool for every researcher interested to study metabolic networks in situ.

Proteomics show antigen presentation processes in human immune cells after AS03-H5N1 vaccination.

Adjuvants enhance immunity elicited by vaccines through mechanisms that are poorly understood. Using a systems biology approach, we investigated temporal protein expression changes in five primary human immune cell populations: neutrophils, monocytes, natural killer cells, T cells, and B cells after administration of either an Adjuvant System 03 adjuvanted or unadjuvanted split-virus H5N1 influenza vaccine. Monocytes demonstrated the strongest differential signal between vaccine groups. On day 3 post-vaccination, several antigen presentation-related pathways, including MHC class I-mediated antigen processing and presentation, were enriched in monocytes and neutrophils and expression of HLA class I proteins was increased in the Adjuvant System 03 group. We identified several protein families whose proteomic responses predicted seroprotective antibody responses (>1:40 hemagglutination inhibition titer), including inflammation and oxidative stress proteins at day 1 as well as immunoproteasome subunit (PSME1 and PSME2) and HLA class I proteins at day 3 in monocytes. While comparison between temporal proteomic and transcriptomic results showed little overlap overall, enrichment of the MHC class I antigen processing and presentation pathway in monocytes and neutrophils was confirmed by both approaches.

Macrophage interactions with polylactic acid and chitosan scaffolds lead to improved recruitment of human mesenchymal stem/stromal cells: a comprehensive study with different immune cells.

Despite the importance of immune cell-biomaterial interactions for the regenerative outcome, few studies have investigated how distinct three-dimensional biomaterials modulate the immune cell-mediated mesenchymal stem/stromal cells (MSC) recruitment and function. Thus, this work compares the response of varied primary human immune cell populations triggered by different model scaffolds and describes its functional consequence on recruitment and motility of bone marrow MSC. It was found that polylactic acid (PLA) and chitosan scaffolds lead to an increase in the metabolic activity of macrophages but not of peripheral blood mononuclear cells (PBMC), natural killer (NK) cells or monocytes. PBMC and NK cells increase their cell number in PLA scaffolds and express a secretion profile that does not promote MSC recruitment. Importantly, chitosan increases IL-8, MIP-1, MCP-1 and RANTES secretion by macrophages while PLA stimulates IL-6, IL-8 and MCP-1 production, all chemokines that can lead to MSC recruitment. This secretion profile of macrophages in contact with biomaterials correlates with the highest MSC invasion. Furthermore, macrophages enhance stem cell motility within chitosan scaffolds by 44% but not in PLA scaffolds. Thus, macrophages are the cells that in contact with engineered biomaterials become activated to secrete bioactive molecules that stimulate MSC recruitment.