Infiltration Of Peripheral Blood Mononuclear Cells Research Articles

Abstract B045: Sensitizing the PDAC tumor microenvironment to immune checkpoint therapies: characterization of a PDAC 3D model to decipher immune infiltration

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal solid tumor with an unfavorable prognosis, often resistant to conventional treatments due to its dense stroma rich in Cancer- Associated Fibroblasts (CAFs). Limited T cell infiltration and prevalence of immunosuppressive cells within the tumor hinder the efficacy of immune checkpoint inhibitors (ICIs). The objective of our project is to modify immune landscape of PDAC tumor microenvironment (TME) to induce ICIs sensitization. We thus develop novel therapeutic strategies combining an immunomodulatory cytokine Interleukine-15 (IL15), with conventional chemotherapies (Gemcitabine or Folfirinox). To accurately replicate the complex cancer-stroma interactions within the pancreatic tumor microenvironment, we constructed a three-dimensional in vitro heterospheroid model composed of xenograft-derived tumor cells from PDAC patients, both primary or immortalized CAFs, and peripheral blood mononuclear cells (PBMCs) from healthy donors. Human 3D models were first set up and characterized by cytometry, imaging mass spectrometry and immunohistochemistry. We showed that, CAFs produce components of the extracellular matrix, promote tumor cell growth, improve resistance to chemotherapy and are able to down-regulate immune cell infiltration and modulate the nature of infiltrated immune cells. Spatial analysis of spheroids using imaging mass cytometry show that CAF influences the distribution of immune cells in our models. Interestingly, Interleukine 15 treatment prompted robust infiltration of PBMCs into heterospheroids. Immunophenotyping experiments revealed a substantial shift in the nature of immune infiltration, marked by a pronounced increase in CD4+ and CD8+ T lymphocytes, gDelta T cell and NK cell populations. When combined with Gemcitabine and IL15, immune effector cell infiltration is remarkably increased, resulting in antitumoral effects and control of tumor cell growth. Moreover, therapeutic combinations induce activation of infiltrated immune effector cells with an increase of activation, degranulation and cytotoxic markers, such as IFNγ, CD107a, and Granzyme B respectively. Thus, the heterotypic spheroids described in our study are a suitable in vitro model to both characterize the influence of CAF on therapeutic effects and the mechanisms that drives immune suppressive microenvironment. Moving forward, the next steps will consist to conduct in vivo experiments using a syngeneic PDAC orthotopic model to assess whether this combined therapeutic approach sensitize the PDAC microenvironment to anti-PD1 therapies. Citation Format: Thomas Bessede, Clara Freixinos, Jennifer Barrat, Véronique Garambois, Nadia Vie, Henri-Alexandre Michaud, Julien Faget, Nathalie Bonnefoy, Céline Gongora, Bruno Robert, Laurent Gros, Christel Larbouret. Sensitizing the PDAC tumor microenvironment to immune checkpoint therapies: characterization of a PDAC 3D model to decipher immune infiltration [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr B045.

Abstract B046: Sensitizing the PDAC tumor microenvironment to immune checkpoint therapies: characterization of a PDAC 3D model to decipher immune infiltration

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal solid tumor with an unfavorable prognosis, often resistant to conventional treatments due to its dense stroma rich in Cancer- Associated Fibroblasts (CAFs). Limited T cell infiltration and prevalence of immunosuppressive cells within the tumor hinder the efficacy of immune checkpoint inhibitors (ICIs). The objective of our project is to modify immune landscape of PDAC tumor microenvironment (TME) to induce ICIs sensitization. We thus develop novel therapeutic strategies combining an immunomodulatory cytokine Interleukine-15 (IL15), with conventional chemotherapies (Gemcitabine or Folfirinox). To accurately replicate the complex cancer-stroma interactions within the pancreatic tumor microenvironment, we constructed a three-dimensional in vitro heterospheroid model composed of xenograft-derived tumor cells from PDAC patients, both primary or immortalized CAFs, and peripheral blood mononuclear cells (PBMCs) from healthy donors. Human 3D models were first set up and characterized by cytometry, imaging mass spectrometry and immunohistochemistry. We showed that, CAFs produce components of the extracellular matrix, promote tumor cell growth, improve resistance to chemotherapy and are able to down-regulate immune cell infiltration and modulate the nature of infiltrated immune cells. Spatial analysis of spheroids using imaging mass cytometry show that CAF influences the distribution of immune cells in our models. Interestingly, Interleukine 15 treatment prompted robust infiltration of PBMCs into heterospheroids. Immunophenotyping experiments revealed a substantial shift in the nature of immune infiltration, marked by a pronounced increase in CD4+ and CD8+ T lymphocytes, gDelta T cell and NK cell populations. When combined with Gemcitabine and IL15, immune effector cell infiltration is remarkably increased, resulting in antitumoral effects and control of tumor cell growth. Moreover, therapeutic combinations induce activation of infiltrated immune effector cells with an increase of activation, degranulation and cytotoxic markers, such as IFNγ, CD107a, and Granzyme B respectively. Thus, the heterotypic spheroids described in our study are a suitable in vitro model to both characterize the influence of CAF on therapeutic effects and the mechanisms that drives immune suppressive microenvironment. Moving forward, the next steps will consist to conduct in vivo experiments using a syngeneic PDAC orthotopic model to assess whether this combined therapeutic approach sensitize the PDAC microenvironment to anti-PD1 therapies. Citation Format: Thomas Bessede, Clara Freixinos, Jennifer Barrat, Véronique Garambois, Nadia Vie, Henri-Alexandre Michaud, Julien Faget, Nathalie Bonnefoy, Céline Gongora, Bruno Robert, Laurent Gros, Christel Larbouret. Sensitizing the PDAC tumor microenvironment to immune checkpoint therapies: characterization of a PDAC 3D model to decipher immune infiltration [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr B046.

Abstract 389: The role of endoplasmic reticulum stress in immune surveillance and effectiveness of immunotherapy in renal and ovarian carcinoma

Abstract In complex tumor-host interactions, the immune response has a dual role, with the capacity to both promote and suppress tumor growth, requiring complex interactions of regulatory molecules within the cellular network of the tumor-immune microenvironment (TIME). Various factors in TIME, such as low pH and hypoxia, cause Endoplasmic Reticulum Stress (ERS). Immune cells exposed to ERS lack antigen presentation, exhibit a suppressor phenotype, and can initiate apoptosis. Therefore, relieving ERS can benefit immune surveillance and response to immunotherapy. Our research is focused on tumor-immune cells interaction, specifically in ovarian and renal cancers. We conducted in vitro co-cultures of these cancer cells with peripheral blood mononuclear cells (PBMC) and manipulated ERS using a well-established ERS inducer tunicamycin and a chemical chaperone tauroursodeoxycholic acid (TUDCA). We then employed various techniques such as MTT, RT-qPCR, western blotting, immunofluorescence staining, scratch wound assay, and 3D co-cultures to analyze cellular viability, gene expression, protein levels of ERS markers (e.g., BiP, CHOP, PERK), immune cell activity (e.g., IL-2, INFγ, FoxP3, PD-1), migration, invasiveness, interaction, spheroid formation, and immune cell infiltration. Furthermore, we examined ERS and immune profiles in tumor samples from patients with ovarian and renal cancer who underwent conventional therapy or immunotherapy.Relieving ERS increased the infiltration of PBMC into tumor spheroids and reduced the expression of BiP and PERK in PBMC. In vitro, the viability of ovarian and renal cancer cells increased when cultured alone after ERS alleviation. However, when co-cultured with PBMC, their viability decreased, indicating enhanced immune cell response. Additionally, the growth and migration of ovarian and renal cancer cells were limited in these co-cultures, along with increased expression of BiP and CHOP and an elevated CHOP/BiP ratio. We connected these findings to the molecular background of ERS in patient samples and observed a positive correlation between a favorable clinical outcome, higher lymphocyte infiltration at the tumor site, and increased levels of BiP and CHOP in cancer cells. We further applied these results to OC and RCC in vivo syngeneic mouse models, currently with very promising outcomes.Based on these results we expect ERS alleviation as a suitable approach to improving the survival and effectiveness of immune cell populations within hostile tumor-induced microenvironment with positive effects on anticancer immunotherapy. Supported by Ministry of Health of the Czech Republic, grant nr. NU21-03-00539, and by the Johannes Amos Comenius Programme, project SALVAGE nr. CZ.02.01.01/00/22_008/0004644. All rights reserved. Citation Format: Marek Svoboda, Lukas Moran, Barbora Vavrusakova, Lenka Krejci, Kamila Souckova, Katerina Vasickova, Milos Holanek. The role of endoplasmic reticulum stress in immune surveillance and effectiveness of immunotherapy in renal and ovarian carcinoma [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 389.

An In Vitro Model of the Blood-Brain Barrier to Study Alzheimer's Disease: The Role of β-Amyloid and Its Influence on PBMC Infiltration.

The blood-brain barrier (BBB) is a highly specialized structure, constituted by endothelial cells that together with astrocytes and pericytes provide a functional interface between the central nervous system and the periphery. Several pathological conditions may affect its functions, and lately BBB involvement in the pathogenesis of Alzheimer's disease has been demonstrated. Both endothelial cells and astrocytes can be differentially affected during the course of the disease. In vitro BBB models present a powerful tool in evaluating the effects that β-amyloid (Aβ), or other pathogenic stimuli, play on the BBB at cellular level. In vitro BBB models derived from human cell sources are rare and not easily implemented. We generated two conditionally immortalized human cell lines, brain microvascular endothelial cells (TY10), and astrocytes (hAST), that, when co-cultured under appropriate conditions, exhibit BBB-like characteristics. This model allowed us to evaluate the transmigration of peripheral blood mononuclear cells (PBMCs) through the in vitro barrier exposed to Aβ and the role played by astrocytes in the modulation of this phenomenon. We describe here the methodology used in our lab to set up our in vitro model of the BBB and to carry out a PBMC transmigration assay.

Immune abnormalities and differential gene expression in the hippocampus and peripheral blood of patients with Alzheimer's disease.

BackgroundDespite decades of research, no precise mechanisms of Alzheimer’s disease (AD) development have been elucidated. This study aimed to investigate novel diagnostic biomarkers in both peripheral blood cells and hippocampus tissue, and the pathogenesis of memory impairment in AD.MethodsmRNA microarray data, including hippocampus samples (GSE1297 and GSE5281) and peripheral blood mononuclear cells (PBMCs) (GSE63060 and GSE63061), associated with AD were obtained from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) between AD and normal-aging samples were screened through a comprehensive analysis of multiple gene expression spectra after gene reannotation and batch normalization. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were used to analyze hub genes and to discover potential biomarkers related to AD. Protein-protein interaction (PPI) network maps were constructed to visualize the correlation between possible genes. The CIBERSORT algorithm was built to explore the patterns of PBMC infiltration to investigate the role of inflammation in the pathogenesis of AD.ResultsThe bioinformatics analysis indicated 1,261 DEGs in the hippocampal samples and 290 in PBMCs when comparing patients with AD with normal-aging individuals. We selected 28 genes co-expressed in the hippocampus and PBMCs. A functional analysis of differential genes revealed that they were primarily involved in neuronal death, immune response, and mitochondrial function. Further, immune cell infiltration patterns demonstrated that the levels of naive CD4+ T cells, resting natural killer cells, M0 macrophages, and activated mast cells were higher in the peripheral blood of patients with AD, while resting memory CD4+ T cells were significantly lower.ConclusionsThe key gene changes present in both the hippocampus and PBMCs highly suggest their utility as an AD biomarker. In addition, according to our present results, immune abnormalities may have an important role in AD pathophysiology. When patients display these peripheral blood immune abnormalities, they may be recognized as being at high risk of developing AD.

Abstract PR-001: Ex vivo co-culture system with patient-derived organoids to assess CXCR4 inhibitor as an immune modulating agent for human pancreas adenocarcinoma

Abstract Introduction: Immune checkpoint blockade either alone or in combination with chemotherapy has been ineffective in pancreatic ductal adenocarcinoma (PDAC) likely due to underlying immunosuppressive pathways. The C-X-C chemokine receptor type 4 (CXCR4)/chemokine (C-X-C motif) ligand 12 (CXCL12) axis is a key immunosuppressive pathway where CXCL12 released by cancer-associated fibroblasts (CAF) binds to its receptor CXCR4 expressed by cytotoxic CD8+ T cells (CTL) which results in their decreased abundance within tumors. Encouraging preclinical and clinical data from mouse PDAC models and human PDAC tumor sections have shown T cell tumor accumulation after co-inhibition of CXCR4 and PD1/PDL1, however number of tumor regressions were limited. Results: To further explore the mechanism by which inhibition of the CXCR4/CXCL12 pathway modulates the immune TME in triggering an anti-tumor immune response in human PDAC, we generated an autologous co-culture system with patient-derived tumor organoids (PDTO) and peripheral blood mononuclear cells (PBMC). PDAC tumor tissue from surgical resection was used to generate lines of PDTO that recapitulate the histological and genetic characteristics of the original tumor. We demonstrate that tumor-specific reactive T cells can be obtained in PDAC by co-culture with autologous PDTO, with up to 5% of CD8+ T cells producing IFNγ after tumor organoid stimulation. No T cell reactivity was observed against normal pancreatic organoids, and blocking tumor MHC I/MHC II decreased the proportion of activated T cells. Ex vivo migration assays were established to better understand the role of CXCL12 in PDAC tumor T cell exclusion. Tumor organoids attracted autologous PBMC and addition of recombinant CXCL12 decreased PBMC migration, while treatment of PBMC with the CXCR4 inhibitor AMD3100, rescued the number of PBMCs that were able to migrate towards the tumor organoids. PBMC infiltrated PDTO-containing but not empty Matrigel domes. Addition of AMD3100 increased PBMC infiltration within the Matrigel dome containing PDTOs. Finally, we found that pre-treatment of PBMC with AMD3100 increased T cell reactivity against PDTO, and that T cell activation was further increased when stimulated with PDTO pre-treated with chemotherapy. Conclusions: We found that CXCL12 modulates the migration of T cells towards tumor organoids generated from pancreatic cancer tissue, and that inhibition of CXCR4 not only increases the migration potential, but also increases tumor-specific T cell activation. The use of ex vivo autologous co-culture and migration assays provide a unique strategy to identify modulators that may enhance T cell mediated neoplastic cell death to guide therapeutic intervention in PDAC. Citation Format: Emily Alouani, Ilenia Pellicciotta, Winston Wong, Alexander S. Thomas, Michael D. Kluger, Anna M. Chiarella, Anil K. Rustgi, Gulam A. Manji. Ex vivo co-culture system with patient-derived organoids to assess CXCR4 inhibitor as an immune modulating agent for human pancreas adenocarcinoma [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2021 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2021;81(22 Suppl):Abstract nr PR-001.

Ruxolitinib, a JAK1/2 Inhibitor, Is Efficacious in a Novel Humanized GvHD Model Characterized By Enhanced NK, NK-T and T-Cell Engraftment

Background: Graft-versus-host disease (GvHD) is defined as a syndrome in which cells originating from a donor recognize and mount a deleterious immune response against antigens found in the immunocompromised recipient. Most humanized pre-clinical studies of models of GvHD rely on adoptive transfer of human peripheral blood mononuclear cells (PBMC) into severely immunodeficient recipient animals. Transferred PBMC can recognize murine xeno-antigens presented by major histocompatibility complex (MHC) and develop GvHD. Only limited numbers of transferred human T-cells survive, and tissue damage is generally observed in only a few tissues (i.e. gastrointestinal (GI) tract and liver). There is a need to develop refined humanized models that better recapitulate the clinical settings of allogeneic hematopoietic cell transplantation. Aims: a) To develop a refined model of pre-clinical GvHD where NOG animals transgenic for human IL-15 (hIL-15 NOG) are able to support long-term engraftment of T-cells as well as NK cells. b) To characterize the role of JAK1/2 inhibition on steroid refractory GvHD in the hIL-15 NOG model. Materials and Methods: Xenogeneic GvHD was induced in hIL-15 NOG receiving 3 different doses of human PBMCs, as well as in control NOG animals. Engraftment was weekly assessed by flow cytometry. Ruxolitinib, prednisolone or vehicle was orally administered twice daily. Efficacy was assessed by GvHD symptom scores, cachexia, and histological analysis of end organ damage. Results: hIL-15 NOG animals develop a rapid onset, highly aggressive, form of GvHD after adoptive transfer of 5x106 PBMC, including a significant engraftment of NK, NK-T and T-cells. Significant PBMC infiltration and inflammation was found in GI tract, lung, liver, skin, eyes and pancreas. Ruxolitinib treatment, but not prednisolone, ameliorated GvHD severity scores with concomitant reduction of GI tract infiltration and tissue damage. Overall GvHD mice survival was significantly improved with JAK1/2 inhibition. Therapeutic ruxolitinib treatment initiated after steroid failure significantly inhibited the chronic-progressive disease and reduced tissue markers of inflammation and fibrosis. Conclusion: hIL-15 NOG animals develop a rapid onset, highly reproducible, form of GvHD after PBMC transfer, with successful engraftment of NK, NK-T and T-cells. Ruxolitinib, a potent and selective JAK1/2 inhibitor, significantly ameliorated GvHD scores, reduced tissue-inflammation and improved survival. Ruxolitinib was also able to improve clinical parameters in mice unresponsive to prednisolone treatment, underscoring the relevance of the new model. Ruxolitinib has demonstrated statistically significant improvement in in patients with steroid-refractory GvHD (REACH3, NCT03112603). Disclosures Huarte: Incyte corporation: Current Employment. Peel:Incyte corporation: Current Employment. Dube:Taconic: Current Employment. Stephens:Incyte: Current Employment. Stewart:Incyte: Current Employment. Long:Incyte: Current Employment. Czerniak:Incyte: Current Employment. Oliver:Incyte: Current Employment. Smith:Incyte corporation: Current Employment.

Peripheral Blood Mononuclear Cells Infiltration Downregulates Decidual FAAH Activity in an LPS-Induced Embryo Resorption Model.

Maternal infections with gram-negative bacteria are associated with miscarriage and are one of the most common complications during pregnancy. Previous studies from our group have shown that lipopolysaccharide (LPS)-activated infiltrating peripheral blood mononuclear cells (PBMC) into decidual tissue plays an important role in the establishment of a local inflammatory process that results in embryo cytotoxicity and early embryo resorption. Moreover, we have also shown that an increased endocannabinoid tone mediates LPS-induced deleterious effects during early pregnancy loss. Here, we sought to investigate whether the infiltrating PBMC modulates the decidual endocannabinoid tone and the molecular mechanisms involved. PBMC isolated from 7-day pregnant mice subjected to different treatments were co-cultured in a transwell system with decidual tissue from control 7-day pregnant mice. Decidual fatty acid amide hydrolase (FAAH) activity was measured by radioconvertion, total decidual protein nitration by Western blot (WB), and decidual FAAH nitration by immunoprecipitation followed by WB. We found that co-culture of PBMC obtained from LPS-treated mice increased the level of nitration of decidual FAAH, which resulted in a negative modulation of decidual FAAH activity. Interestingly, co-treatment with progesterone or aminoguanidine prevented this effect. We found that LPS-treated PBMC release high amounts of nitric oxide (NO) which causes tyrosine nitration of decidual FAAH, diminishing its enzymatic activity. Inactivation of FAAH, the main degrading enzyme of anandamide and similar endocannabinoids, could lead to an increased decidual endocannabinoid tone with embryotoxic effects. J. Cell. Physiol. 232: 1441-1447, 2017. © 2016 Wiley Periodicals, Inc.

Infiltration of lymphocyte subpopulations into cancer microtissues as a tool for the exploration of immunomodulatory agents and biomarkers

IntroductionThe interaction between the immune system and malignant diseases is a proven key target for cancer therapy. We describe an innovative 3D cell culture system comprising both immune and cancer cells to evaluate their interaction and immune cell infiltration to provide an innovative in vitro screening of immunomodulatory agents and biomarkers. Methods3D tumor microtissues were cultivated using a hanging drops system. Human non-small-cell lung cancer cell lines were incubated for 7 days to form microtissues. On day 5, peripheral blood mononuclear cells (PBMC) were added with or without interleukin-2 (IL-2) for 24 or 48h. Viability of cancer cells and the infiltrating PBMC subpopulations were investigated by flow cytometry. Aggregation of tumor cells and PBMC and the infiltration of the PBMC into the tumor microtissues were analyzed by immunohistochemistry. Quantification of infiltration was measured by applying the TissueFAXS system. ResultsImmunohistochemistry revealed PBMC infiltration in all cell lines which increased under IL-2 stimulation. Analysis of infiltrating populations showed both lymphocyte subpopulations and monocytes within the tumor microtissues. In all three co-cultures, CD3+CD8+ and CD3+CD8+CD45R0+CD28+ lymphocytes were increased with IL-2, whereas CD3+CD8+CD45R0-CD28+ PBMCs were decreased with and without IL-2 stimulation. ConclusionIn summary, we present a novel cell culture system to study the interaction between cancer cells and immune cells in 3-dimensional microtissues. In addition, we report for the first time an in vitro infiltration assay based on 3D microtissues. This model has the potential to provide a tool for ex-vivo drug testing and biomarker screening of immunomodulatory agents.

Isolation and Flow Cytometric Analysis of Glioma-infiltrating Peripheral Blood Mononuclear Cells.

Our laboratory has recently demonstrated that natural killer (NK) cells are capable of eradicating orthotopically implanted mouse GL26 and rat CNS-1 malignant gliomas soon after intracranial engraftment if the cancer cells are rendered deficient in their expression of the β-galactoside-binding lectin galectin-1 (gal-1). More recent work now shows that a population of Gr-1+/CD11b+ myeloid cells is critical to this effect. To better understand the mechanisms by which NK and myeloid cells cooperate to confer gal-1-deficient tumor rejection we have developed a comprehensive protocol for the isolation and analysis of glioma-infiltrating peripheral blood mononuclear cells (PBMC). The method is demonstrated here by comparing PBMC infiltration into the tumor microenvironment of gal-1-expressing GL26 gliomas with those rendered gal-1-deficient via shRNA knockdown. The protocol begins with a description ofhow to culture and prepare GL26 cells for inoculation into the syngeneic C57BL/6J mouse brain. It then explains the steps involved in the isolation and flow cytometric analysis of glioma-infiltrating PBMCs from the early brain tumor microenvironment. The method is adaptable to a number of in vivo experimental designs in which temporal data on immune infiltration into the brain is required. The method is sensitive and highly reproducible, as glioma-infiltrating PBMCs can be isolated from intracranial tumors as soon as 24 hr post-tumor engraftment with similar cell counts observed from time point matched tumors throughout independent experiments. A single experimentalist can perform the method from brain harvesting to flow cytometric analysis of glioma-infiltrating PBMCs in roughly 4-6 hr depending on the number of samples to be analyzed. Alternative glioma models and/or cell-specific detection antibodies may also be used at the experimentalists' discretion to assess the infiltration of several other immune cell types of interest without the need for alterations to the overall procedure.

ITOC2 – 034. Development of a 3D cell culture model for the investigation of cancer cell/immune cell interactions

Background Recent studies have shown the obvious interaction between cancer cells and immune cells. These effects can be hardly studied in conventional culture systems using cell monolayers. Therefore, alternative in vitro models are required. We describe a novel 3D cell culture model and a 3D migration assay for investigating cancer cell/immune cell interactions. Methods A multi-well hanging drops system was used to produce 3D tumour spheres. The human NSCLC cell lines A549, Calu-6 and Colo699 were incubated for 6 and 7 days in the hanging drops to form spheroids. On day 5, peripheral blood mononuclear cells (PBMC) were added either with or without interleukin-2 (IL-2). Viability was investigated via flowing cytometry. Invasion of PBMC into the tumour spheres was measured by performing immunohistochemistry. Results No effect on cell viability was observed in A549 and Colo699 spheroids. In Calu-6 spheroids, a significant PBMC induced cytotoxic effect was measured, what was even stronger under IL-2 stimulation. Immunohistochemical staining revealed PBMC infiltration in all three cell lines. Under IL-2 stimulation, infiltration of PBMC increased in Calu-6 and Colo699 spheroids. Conclusion This work provides evidence that our 3D co-culture model is a reliable and effective approach to study interactions between cancer cells and immune cells. Additionally, we were able to establish for the first time an innovative ex vivo infiltration assay based on 3D microtissues.

Cathepsin D deficiency induces oxidative damage in brain pericytes and impairs the blood-brain barrier.

Recent evidence suggests that peripheral blood mononuclear cells (PBMCs) contribute to the pathogenesis of neuropathological changes in patients with neuronal ceroid lipofuscinosis (NCL) and lysosomal storage diseases. In order to examine the possible increase in the permeability of the blood-brain-barrier (BBB) and resultant infiltration of PBMCs due to cathepsin D (CatD) deficiency, a process underlying the onset of congenital NCL, we examined structural changes in brain vessels in CatD-/- mice. Consequently, the mean diameter of the brain vessels in the cerebral cortex on postnatal day 24 (P24) was significantly larger in CatD-/- mice than in wild-type mice. Furthermore, the mean number of brain pericytes in CatD-/- mice began to decline significantly on P16 and almost disappeared on P24, and oxidative DNA damage was first detected in brain pericytes on P12. Examinations with electron microscopy revealed that brain pericytes were laden with dense granular bodies, cytoplasmic vacuoles and lipid droplets. The infiltration of PBMCs characterized by segmented nucleus laden with dense granular bodies was also noted in the cerebral cortex of CatD-/- mice. When primary cultured microglia prepared from enhanced green fluorescent protein (GFP)-expressing transgenic rats were injected into the common carotid artery, GFP-positive microglia were detected in the brain parenchyma of CatD-/-, but not wild-type, mice. Moreover, pepstatin A, a specific aspartic protease inhibitor, induced mitochondria-derived reactive oxygen species (ROS) production in the isolated brain pericytes, which decreased the cell viability. These observations suggest that increased lysosomal storage due to CatD deficiency causes oxidative damage in brain pericytes, subsequently resulting in an increased vessel diameter, enhanced permeability of the BBB and the infiltration of PBMCs. Therefore, protecting brain pericytes against lysosomal storage-induced oxidative stress may represent an alternative treatment strategy for congenital NCL.

Abstract 1655: Human immune cell infiltration of tumors in a PBMC-humanized NSG mouse xenograft model changes with treatment of an anti-tissue factor antibody

Abstract Immunocompromised mice engrafted with human hematopoietic stem cells (HSC) or peripheral blood mononuclear cells (PBMC) can be promising models of human immune system compartments, useful for studying diseases such as diabetes, lupus, GVHD, and cancer. We have utilized the PBMC-humanized mouse as a platform for xenograft models. To investigate the effect of human antibody (Ab) treatment on immune cells and xenografts using this platform, we examined the infiltrate of human immune cells in A431 xenografts with treatment of an effector function-enhanced anti-tissue factor VIIA (TFVIIA) Ab. Female NSG mice were intravenously engrafted with human PBMC, and subcutaneously implanted two weeks later with A431 human SCC cells. One week post tumor cell implant and thereafter twice weekly, mice received treatment with anti-TFVIIA Ab. Peripheral blood, bone marrow and spleen were analyzed by FACS and terminal tumor samples were analyzed by FACS and immunohistochemistry (IHC). FACS analysis of blood from Ab treated and untreated tumor-bearing mice collected from baseline to termination, showed an overall increase in the frequency of human CD45+, CD3+, CD8+, and CD4+ cells, while the frequency of CD56+ cells remained stable. In comparison, non-tumor bearing mice had increased CD56+ cells and decreased CD3+ cells. FACS analysis of tumors showed a robust increase in the frequency of CD56+ cells and a decrease in the frequency of CD3+ cells with treatment of anti-TF Ab. With treatment, the frequency of CD8+ cells was markedly lower and the frequency of CD4+ cells unchanged. Histological analysis was performed on A431 FFPE xenografts from both the treated and non-treated groups. Hematoxylin and eosin (H&E) staining of the xenografts confirmed the presence of inflammatory cells in the tumors and also showed greater PBMC infiltration of the tumors in the presence of the anti-TFVIIA Ab. Xenografts treated with anti-TFVIIA Ab exhibited greater infiltration of human CD3+, CD8+, and CD57+ cells. There was an increase in cleaved caspase-3 (CC3)+ cells in Ab-treated xenografts, indicating an increase in apoptosis with anti-TFVIIA Ab treatment. In conclusion, anti-TFVIIA Ab treatment causes changes in immune cell populations in xenografts. While the mechanism is unknown, one possibility is that NK migration into the tumor coupled with increased apoptosis with treatment indicates ADCC activity by the NK cells. This would signify some preservation of immune cell function in the PBMC engraftment model, and would enhance studying the effects of experimental antibodies in a more humanized setting. Citation Format: Hillary Millar-Quinn, Brenda Hertzog, Rebecca Hanson, Jeffrey Nemeth, John Alvarez. Human immune cell infiltration of tumors in a PBMC-humanized NSG mouse xenograft model changes with treatment of an anti-tissue factor antibody. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1655. doi:10.1158/1538-7445.AM2014-1655

Peripheral blood mononuclear cell infiltration and neuroinflammation in the HexB −/− mouse model of neurodegeneration

Myeloid-derived immune cells, including microglia, macrophages and monocytes, have been previously implicated in neurodegeneration. We investigated the role of infiltrating peripheral blood mononuclear cells (PBMC) in neuroinflammation and neurodegeneration in the HexB −/− mouse model of Sandhoff disease. Ablation of the chemokine receptor CCR2 in the HexB −/− mouse resulted in significant inhibition of PBMC infiltration into the brain, decrease in TNFα and MHC-II mRNA abundance and retardation in clinical disease development. There was no change in the level of GM 2 storage and pro-apoptotic activity or astrocyte activation in HexB −/−;Ccr2 −/− double knockout mice, which eventually succumbed secondary to GM 2 gangliosidosis.