Innate Immune Cell Populations Research Articles

Investigation of hub genes and immune status in heart transplant rejection using endomyocardial biopsies.

T cell‒mediated rejection (TCMR) and antibody‐mediated rejection (ABMR) are severe post‐transplantation complications for heart transplantation (HTx), whose molecular and immunological pathogenesis remains unclear. In the present study, the mRNA microarray data set GSE124897 containing 645 stable, 52 TCMR and 144 ABMR endomyocardial biopsies was obtained to screen for differentially expressed genes (DEGs) between rejected and stable HTx samples and to investigate immune cell infiltration. Functional enrichment analyses indicated roles of the DEGs primarily in immune‐related mechanisms. Protein‐protein interaction networks were then constructed, and ICAM1, CD44, HLA‐A and HLA‐B were identified as hub genes using the maximal clique centrality method. Immune cell infiltration analysis revealed differences in adaptive and innate immune cell populations between TCMR, ABMR and stable HTx samples. Additionally, hub gene expression levels significantly correlated with the degree and composition of immune cell infiltration in HTx rejection samples. Furthermore, drug‐gene interactions were constructed, and 12 FDA‐approved drugs were predicted to target hub genes. Finally, an external GSE2596 data set was used to validate the expression of the hub genes, and ROC curves indicated all four hub genes had promising diagnostic value for HTx rejection. This study provides a comprehensive perspective of molecular and immunological regulatory mechanisms underlying HTx rejection.

Liver Cancer Immunity.

Primary liver cancer has an increasing incidence and poor patient outcomes. Potentially curative options such as surgical resection or liver transplantation are limited to the subset of patients with early-stage disease. The available systemic treatment options have limited efficacy. Immuno-oncology has revolutionized cancer treatment across a variety of malignancies, although durable responses occur in a minority of patients. Immune-based approaches have garnered significant interest in both hepatocellular carcinoma and cholangiocarcinoma given the etiologic association of these malignancies with inflammation. The liver cancer tumor immune microenvironment is complex with diverse populations of innate and adaptive immune cells that impact cancer immune evasion, response to immunotherapy, and patient survival. Although the response rate to immune checkpoint inhibitor monotherapy has been relatively disappointing in liver cancer, emerging combination immunotherapeutic approaches have shown promise. Herein, we review the immune ecosystem of human liver cancer as well as current and emerging combination immunotherapeutic regimens harnessing immune checkpoint inhibition with molecularly targeted therapy, locoregional therapy, and immune microenvironment targeted therapy.

Metabolite Transporters as Regulators of Immunity.

In the past decade, the rise of immunometabolism has fundamentally reshaped the face of immunology. As the functions and properties of many (immuno)metabolites have now been well described, their exchange among cells and their environment have only recently sparked the interest of immunologists. While many metabolites bind specific receptors to induce signaling cascades, some are actively exchanged between cells to communicate, or induce metabolic reprograming. In this review, we give an overview about how active metabolite transport impacts immune cell function and shapes immunological responses. We present some examples of how specific transporters feed into metabolic pathways and initiate intracellular signaling events in immune cells. In particular, we focus on the role of metabolite transporters in the activation and effector functions of T cells and macrophages, as prototype adaptive and innate immune cell populations.

Development, phenotypes of immune cells in BTBR T+Itpr3tf/J mice

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition that is characterized by a lack of social interaction, decreased verbal and non-verbal communication skills, and stereotyped repetitive behavior. There is strong evidence that a dysregulated immune response may influence neurodevelopment and thus may have a role in the development of ASD. This study focuses on the characterization of immune cell phenotypes in the BTBR T+Itpr3tf/J (BTBR) mouse strain, a widely used animal model for autism research. Our study demonstrated that BTBR mice have a different immune profile compared to C57BL/6J (B6) mice, which do not display ASD-like characteristics. Thymic cells of BTBR mice have more single positive (SP) CD4+ and CD8+ T cells and fewer double positive (DP) T cells than B6 mice. The development of T cells is increased in BTBR mice with regard to the double negative (DN4) population being much higher in BTBR mice. The spleens and blood of BTBR mice also have more T helper type 1 (Th1), T helper type 2 (Th2) and T regulatory (Treg) cells compared to B6 mice. Aire expression in the thymus and spleen of BTBR mice compared to B6 mice was equivalent and lower, respectively. The mature natural killer (NK) innate immune cell population in blood and spleen is lower in BTBR than B6 mice; NK cell development is blocked prior to the double positive (DN) CD11b+CD27+ stage in BTBR mice. Since BTBR mice have more CD4+ T cells and elevated numbers of Th1 (T-bet+) and Th2 (GATA3+) cells, their low defense against pathogen may be explained by the lower number of NK cells and the significantly lower Th1 to Th2 ratio. The elevated number of plasma cells and autoantibodies of BTBR mice may be due to less presence and function of splenic AIRE.

Metabolic determinants of leukocyte pathogenicity in neurological diseases.

Neuroinflammatory and neurodegenerative diseases are characterized by the recruitment of circulating blood-borne innate and adaptive immune cells into the central nervous system (CNS). These leukocytes sustain the detrimental response in the CNS by releasing pro-inflammatory mediators that induce activation of local glial cells, blood-brain barrier (BBB) dysfunction, and neural cell death. However, infiltrating peripheral immune cells could also dampen CNS inflammation and support tissue repair. Recent advances in the field of immunometabolism demonstrate the importance of metabolic reprogramming for the activation and functionality of such innate and adaptive immune cell populations. In particular, an increasing body of evidence suggests that the activity of metabolites and metabolic enzymes could influence the pathogenic potential of immune cells during neuroinflammatory and neurodegenerative disorders. In this review, we discuss the role of intracellular metabolic cues in regulating leukocyte-mediated CNS damage in Alzheimer's and Parkinson's disease, multiple sclerosis and stroke, highlighting the therapeutic potential of drugs targeting metabolic pathways for the treatment of neurological diseases.

Transcriptional Profiling Uncovers Human Hyalocytes as a Unique Innate Immune Cell Population.

PurposeTo decipher the transcriptional signature of macrophages of the human vitreous, also known as hyalocytes, and compare it to the profiles of other myeloid cell populations including human blood-derived monocytes, macrophages, and brain microglia.MethodsThis study involves a total of 13 patients of advanced age with disorders of the vitreoretinal interface undergoing vitrectomy at the University Eye Hospital Freiburg between 2018 and 2019. Vitreal hyalocytes were analyzed by fluorescence-activated cell sorting (FACS) and isolated as CD45+CD11b+CX3CR1+Mat-Mac+ cells using a FACS-based sorting protocol. RNA extraction, library preparation and RNA sequencing were performed and the sequencing data was analyzed using the Galaxy web platform. The transcriptome of human hyalocytes was compared to the transcriptional profile of human blood-derived monocytes, macrophages and brain microglia obtained from public databases. Protein validation for selected factors was performed by immunohistochemistry on paraffin sections from three human donor eyes.ResultsOn average, 383 ± 233 hyalocytes were isolated per patient, resulting in 128 pg/μl ± 76 pg/μl total RNA per sample. RNA sequencing revealed that SPP1, FTL, CD74, and HLA-DRA are among the most abundantly expressed genes in hyalocytes, which was confirmed by immunofluorescence for CD74, FTL, and HLA-DRA. Gene ontology (GO) enrichment analysis showed that biological processes such as “humoral immune response,” “leukocyte migration,” and “antigen processing and presentation of peptide antigen” (adjusted p < 0.001) are dominating in vitreal hyalocytes. While the comparison of the gene expression profiles of hyalocytes and other myeloid cell populations showed an overall strong similarity (R2 > 0.637, p < 0.001), hyalocytes demonstrated significant differences with respect to common leukocyte-associated factors. In particular, transcripts involved in the immune privilege of the eye, such as POMC, CD46, and CD86, were significantly increased in hyalocytes compared to other myeloid cell subsets.ConclusionHuman hyalocytes represent a unique and distinct innate immune cell population specialized and adapted for the tissue-specific needs in the human vitreous. Vitreal hyalocytes are characterized by a strong expression of genes related to antigen processing and presentation as well as immune modulation. Thus, hyalocytes may represent an underestimated mediator in vitreoretinal disease and for the immune privilege of the eye.

Activation of Human Vδ2+ γδ T Cells by Staphylococcus aureus Promotes Enhanced Anti-Staphylococcal Adaptive Immunity.

Murine studies have shown the potential for γδ T cells to mediate immunity to Staphylococcus aureus in multiple tissue settings by the secretion of diverse cytokines. However, the role played by γδ T cells in human immune responses to S. aureus is almost entirely unknown. In this study, we establish the capacity of human Vδ2+ γδ T cells for rapid activation in response to S. aureus In coculture with S. aureus-infected monocyte-derived dendritic cells (DCs), Vδ2+ cells derived from peripheral blood rapidly upregulate CD69 and secrete high levels of IFN-γ. DCs mediate this response through direct contact and IL-12 secretion. In turn, IFN-γ released by Vδ2+ cells upregulates IL-12 secretion by DCs in a positive feedback loop. Furthermore, coculture with γδ T cells results in heightened expression of the costimulatory molecule CD86 and the lymph node homing molecule CCR7 on S. aureus-infected DCs. In cocultures of CD4+ T cells with S. aureus-infected DCs, the addition of γδ T cells results in heightened CD4+ T cell activation. Our findings identify γδ T cells as potential key players in the early host response to S. aureus during bloodstream infection, promoting enhanced responses by both innate and adaptive immune cell populations, and support their consideration in the development of host-directed anti-S. aureus treatments.

Abstract 3320: Humanized NSG-Tg(Hu-IL15) mice support preclinical immune-oncology efficacy for testing of NK cells based immunology

Abstract The JAX® Onco-Hu® platform utilizes humanized mice engrafted with tumors to enable in vivo investigation of the interactions between the human immune system and human cancer. A major avenue of our investigation is to generate humanized mouse models containing a more complete human hematopoietic system and robust innate immune cell population. Nature killer (NK) cells are important players of innate defense against cancerous cells by a number of mechanisms, including antibody-dependent cell mediated cytotoxicity (ADCC). To overcome limited NK cell development in humanized NSG™ mice, we have developed NSG-Tg(Hu-IL15) mice constitutively expressing human IL15 in a physiological level. Following CD34+ HSC-engraftment of NSG-Tg(Hu-IL15) mice, significantly higher levels of human NK cells are detectable in peripheral blood as compared to NSG mice and the engraftment is stable for over six months. Levels of circulating human CD45+ cells, CD3+ T cells, and CD33+ myeloid cells are similar between the HSC-engrafted NSG-Tg(Hu-IL15) and NSG mice. Minimal baseline activation of NK cells is detected in the spleen and peripheral blood. Previously we have described that the human NK cells developing in HSC-engrafted NSG-Tg(Hu-IL15) mice are functional and can lyse the NK-sensitive target cells K562 by in vitro cytotoxicity assay. We also showed that NK cells directly limited growth of a PDX melanoma xenograft and NK cell depletion by antibody blockage largely abrogated the delayed PDX growth. Here we extended these observations by evaluating tumor growth of multiple PDX and CDX models in humanized NSG-Tg(Hu-IL15) mice. We found that not all tumors were able to grow and for those that grew some spontaneous regression might still occur. In ex vivo experiments NK cells in the PBMCs isolated from humanized NSG-Tg(Hu-IL15) mice could be activated by Her2+ human cancer cells in the presence of anti-human H2 antibody (Trastuzumab). Furthermore we showed in vivo that humanized NSG-Tg(Hu-IL15) mice mediated efficient ADCC against Daudi B lymphoma cells using anti-human CD20 antibody (Rituximab). Administration of rituximab resulted in significant tumor growth inhibition as measured by both tumor volume and tumor weight. Together these data demonstrate that HSC-engrafted NSG-Tg(Hu-IL15) mice support enhanced development of functional human NK cells and that this mouse model enables preclinical evaluation of NK cell-targeted cancer immunotherapy in vivo. Citation Format: Li-Chin Yao, Mingshan Cheng, Danying Cai, Leonard D. Shultz, James G. Keck. Humanized NSG-Tg(Hu-IL15) mice support preclinical immune-oncology efficacy for testing of NK cells based immunology [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 3320.

Total alkaloids from Alstonia scholaris inhibit influenza a virus replication and lung immunopathology by regulating the innate immune response

BackgroundAlstonia scholaris is a folk medicine used to treat cough, asthma and chronic obstructive pulmonary disease in China. Total alkaloids (TA) from A. scholaris exhibit anti-inflammatory properties in acute respiratory disease, which suggests their possible anti-inflammatory effect on influenza virus infection. PurposeTo assess the clinical use of TA by demonstrating their anti-influenza and anti-inflammatory effects and the possible mechanism underlying the effect of TA on influenza A virus (IAV) infection in vitro and to reveal the inhibitory effect of TA on lung immunopathology caused by IAV infection. MethodsAntiviral and anti-inflammatory activities were assessed in Madin-Darby canine kidney (MDCK) and A549 cells and U937-derived macrophages infected with influenza A/PR/8/34 (H1N1) virus. Proinflammatory cytokine levels were measured by real-time quantitative PCR and Bio-Plex assays. The activation of innate immune signaling induced by H1N1 virus in the absence or presence of TA was detected in A549 cells by Western blot. Furthermore, mice were infected intranasally with H1N1 virus and treated with TA (50, 25 and 12.5 mg/kg/d) or oseltamivir (60 mg/kg/d) for 5 days in vivo. The survival rates and body weight were recorded, and the viral titer, proinflammatory cytokine levels, innate immune cell populations and histopathological changes in the lungs were analyzed. ResultsTA significantly inhibited viral replication in A549 cells and U937-derived macrophages and markedly reduced cytokine and chemokine production at the mRNA and protein levels. Furthermore, TA blocked the activation of pattern recognition receptor (PRR)- and IFN-activated signal transduction in A549 cells. Critically, TA also increased the survival rate, reduced the viral titer, suppressed proinflammatory cytokine production and innate immune cell infiltration and improved lung histopathology in a lethal PR8 mouse model. ConclusionTA exhibits anti-viral and anti-inflammatory effects against IAV infection by interfering with PRR- and IFN-activated signal transduction.

Human Monocyte Subset Distinctions and Function: Insights From Gene Expression Analysis.

Monocytes are a highly plastic innate immune cell population that displays significant heterogeneity within the circulation. Distinct patterns of surface marker expression have become accepted as a basis for distinguishing three monocyte subsets in humans. These phenotypic subsets, termed classical, intermediate and nonclassical, have also been demonstrated to differ in regard to their functional properties and disease associations when studied in vitro and in vivo. Nonetheless, for the intermediate monocyte subset in particular, functional experiments have yielded conflicting results and some studies point to further levels of heterogeneity. Developments in genetic sequencing technology have provided opportunities to more comprehensively explore the phenotypic and functional differences among conventionally-recognized immune cell subtypes as well as the potential to identify novel subpopulations. In this review, we summarize the transcriptomic evidence in support of the existence of three separate monocyte subsets. We also critically evaluate the insights into subset functional distinctions that have been garnered from monocyte gene expression analysis and the potential utility of such studies to unravel subset-specific functional changes which arise in disease states.

Boosting the Immune System for HIV Cure: A γδ T Cell Perspective.

The major barrier to HIV cure is a population of long-lived cells that harbor latent but replication-competent virus, are not eliminated by antiretroviral therapy (ART), and remain indistinguishable from uninfected cells. However, ART does not cure HIV infection, side effects to treatment still occur, and the steady global rate of new infections makes finding a sustained ART-free HIV remission or cure for HIV-seropositive individuals urgently needed. Approaches aimed to cure HIV are mostly based on the “shock and kill” method that entails the use of a drug compound to reactivate latent virus paired together with strategies to boost or supplement the existing immune system to clear reactivated latently infected cells. Traditionally, these strategies have utilized CD8+ cytotoxic lymphocytes (CTL) but have been met with a number of challenges. Enhancing innate immune cell populations, such as γδ T cells, may provide an alternative route to HIV cure. γδ T cells possess anti-viral and cytotoxic capabilities that have been shown to directly inhibit HIV infection and specifically eliminate reactivated, latently infected cells in vitro. Most notably, their access to immune privileged anatomical sites and MHC-independent antigen recognition may circumvent many of the challenges facing CTL-based strategies. In this review, we discuss the role of γδ T cells in normal immunity and HIV infection as well as their current use in strategies to treat cancer. We present this information as means to speculate about the utilization of γδ T cells for HIV cure strategies and highlight some of the fundamental gaps in knowledge that require investigation.

Pathological inflammation in patients with COVID-19: a key role for monocytes and macrophages.

The COVID-19 pandemic caused by infection with SARS-CoV-2 has led to more than 200,000 deaths worldwide. Several studies have now established that the hyperinflammatory response induced by SARS-CoV-2 is a major cause of disease severity and death in infected patients. Macrophages are a population of innate immune cells that sense and respond to microbial threats by producing inflammatory molecules that eliminate pathogens and promote tissue repair. However, a dysregulated macrophage response can be damaging to the host, as is seen in the macrophage activation syndrome induced by severe infections, including in infections with the related virus SARS-CoV. Here we describe the potentially pathological roles of macrophages during SARS-CoV-2 infection and discuss ongoing and prospective therapeutic strategies to modulate macrophage activation in patients with COVID-19.

Identification of pathogenic TRAIL-expressing innate immune cells during HIV-1 infection in humanized mice by scRNA-Seq.

Depletion of CD4+ T cells during HIV-1 infection is mostly mediated by inflammatory cells via indirect but not clearly defined mechanisms. In this report, we used single-cell RNA-Seq (scRNA-Seq) technology to study HIV-induced transcriptomic change in innate immune cells in lymphoid organs. We performed scRNA-Seq on hCD45+hCD3-hCD19- human leukocytes isolated from spleens of humanized NOD/Rag2-/-γc-/- (NRG) mice transplanted with human CD34+ hematopoietic stem progenitor cells (NRG-hu HSC mice). We identified major populations of innate immune cells, including plasmacytoid dendritic cells (pDCs), myeloid dendritic cells (mDCs), macrophages, NK cells, and innate lymphoid cells (ILCs). HIV-1 infection significantly upregulated genes involved in type I IFN inflammatory pathways in each of the innate immune subsets. Interestingly, we found that TRAIL was upregulated in the innate immune populations, including pDCs, mDCs, macrophages, NK cells, and ILCs. We further demonstrated that blockade of the TRAIL signaling pathway in NRG-hu HSC mice prevented HIV-1-induced CD4+ T cell depletion in vivo. In summary, we characterized HIV-induced transcriptomic changes of innate immune cells in the spleen at single-cell levels, identified the TRAIL+ innate immune cells, and defined an important role of the TRAIL signaling pathway in HIV-1-induced CD4+ T cell depletion in vivo.

The inflammatory response after an intestinal inflammatory challenge affects in an opposite manner to the female and male offspring gestated in hypothyroxinemia

Abstract Ulcerative colitis (UC) is a highly frequent inflammatory bowel disease (IBD), which causes are unknown. We have shown that the offspring gestated under thyroxine (T4) deficiency, condition named hypothyroxinemia (HTX), shows inflammatory features at the intestine. Moreover, the offspring gestated under HTX (HTX-offspring) suffers strong experimental autoimmune disease. Suggesting that gestational HTX could imprint their offspring with a high immune response after an inflammatory challenge. Thus, we think that the HTX-offspring will be more prone to suffer IBD. To analyze this hypothesis C57BL6 pregnant mice were induced with gestational HTX during E10 to E15 by giving them methimazole in the tap-drinking water. Then, UC was induced to the HTX-offspring or control at postnatal P55 by giving them dextran sodium sulphate (DSS) in the tap-drinking water for six days. Body weight, pathological score of IBD and hidden blood in stool were analyzed daily. Then, mice were sacrificed at day 10 to evaluate their inflammatory response. For that histological analysis were performed in the intestine; the content of cytokines in serum and intestine by ELISA and the populations of innate and adaptive immune cells at the intestine and spleen by flow cytometry. Our results shown that the male and female offspring developed an opposite immune response to UC. The female HTX-offspring were more resistant and the male HTX-offspring were more sensitive to UC compared to their respective female and male control groups. Thus, our results suggest that the immune response of an individual can be set up during gestation and that the normal level of maternal T4 during gestation is fundamental for the proper function of the offspring immune system.

Microbiome, bile acids, and obesity: How microbially modified metabolites shape anti-tumor immunity.

Bile acids (BAs) are known facilitators of nutrient absorption but recent paradigm shifts now recognize BAs as signaling molecules regulating both innate and adaptive immunity. Bile acids are synthesized from cholesterol in the liver with subsequent microbial modification and fermentation adding complexity to pool composition. Bile acids act on several receptors such as Farnesoid X Receptor and the G protein-coupled BA receptor 1 (TGR5). Interestingly, BA receptors (BARs) are expressed on immune cells and activation either by BAs or BAR agonists modulates innate and adaptive immune cell populations skewing their polarization toward a more tolerogenic anti-inflammatory phenotype. Intriguingly, recent evidence also suggests that BAs promote anti-tumor immune response through activation and recruitment of tumoricidal immune cells such as natural killer T cells. These exciting findings have redefined BA signaling in health and disease wherein they may suppress inflammation on the one hand, yet promote anti-tumor immunity on the other hand. In this review, we provide our readers with the most recent understanding of the interaction of BAs with the host microbiome, their effect on innate and adaptive immunity in health and disease with a special focus on obesity, bariatric surgery-induced weight loss, and immune checkpoint blockade in cancer.

Abstract A75: The role of eosinophils in the lung tumor microenvironment

Abstract Background: The use of immunotherapy to treat lung cancer is becoming increasingly common, highlighting the importance of the immune system in the lung tumor microenvironment. The lungs are host to a variety of immune cell subsets, including eosinophils (Eo), which are a population of innate immune cells that exert cytotoxic effector functions through the release of secretory granules and participate in tissue homeostasis and immunity. Despite the presence of Eo in solid tumors and their prevalence in the lung, the role of Eo in lung cancer is both controversial and largely unexplored. The Bennewith lab has previously found that mice with elevated lung Eo have decreased tumor growth in a model of breast cancer lung metastasis. We hypothesize that Eo play a protective role in lung cancer progression. Methods: In collaboration with Dr. Kelly McNagny (UBC), we used IL-5Tg transgenic mice that overexpress IL-5 and have a systemic expansion of Eo, ddGATA transgenic mice which are Eo-deficient, and ddGATA/IL-5Tg double-transgenic mice (excess IL-5 but no Eo) to study lung cancer. Lewis Lung carcinoma (LLC) cells were injected intravenously (IV) to seed the lungs. After three weeks, we harvested lungs and used flow cytometry to quantify immune cell subsets in the lungs. Additionally, we used clonogenic assays and histology to quantify lung tumor growth. Results: We confirmed that naive ddGATA and ddGATA/IL-5Tg mice have no lung Eo. In contrast, IL-5Tg mice have a 100-fold expansion of Eo in the lungs, and these Eo express higher levels of the Eo activation marker CD11b compared to wild-type (WT) mice. Naive IL-5Tg and ddGATA/IL-5Tg mice had an increased proportion of lung B-1 B cells, as well as an increase in the expression of the apoptosis-inducing cell surface molecule FasL. The absence of Eo in ddGATA mice did not impact lung colonization of LLC cells. Though there was a substantial expansion of Eo in the lungs of IL-5Tg mice compared to WT mice, there was no change in the number of lung-infiltrating Eo three weeks after IL-5Tg and WT mice were injected IV with LLC cells. IL-5Tg mice injected IV with LLC cells had an increase in the total number of lung-infiltrating Bconv and B-1 B cells compared to naive mice, whereas there was no change in B cell subsets between naive and LLC IV injected WT mice. Conclusions: Though Eo may play an antitumorigenic role in the presence of excess IL-5, the absence of Eo in ddGATA mice did not result in an increase in lung tumor burden. This suggests that Eo need to be activated and expanded to exert an antitumorigenic effect, or that the expansion of B cells in IL-5Tg mice is responsible for the decrease in lung tumor growth in IL-5Tg mice relative to WT mice. Illuminating the specific roles Eo and B cells play in lung cancer progression will allow us to better understand the interplay between host immune cells and malignant cells and could reveal new avenues of cancer immunotherapy development. Citation Format: Rachel A. Cederberg, Alvina So, Elizabeth Franks, Jenna Collier, Brennan J. Wadsworth, Michael R. Hughes, Kelly M. McNagny, Kevin L. Bennewith. The role of eosinophils in the lung tumor microenvironment [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr A75.

Dendritic Cell Subsets in Intestinal Immunity and Inflammation.

The mammalian intestine is a complex environment that is constantly exposed to Ags derived from food, microbiota, and metabolites. Intestinal dendritic cells (DC) have the responsibility of establishing oral tolerance against these Ags while initiating immune responses against mucosal pathogens. We now know that DC are a heterogeneous population of innate immune cells composed of classical and monocyte-derived DC, Langerhans cells, and plasmacytoid DC. In the intestine, DC are found in organized lymphoid tissues, such as the mesenteric lymph nodes and Peyer's patches, as well as in the lamina propria. In this Brief Review, we review recent work that describes a division of labor between and collaboration among gut DC subsets in the context of intestinal homeostasis and inflammation. Understanding relationships between DC subtypes and their biological functions will rationalize oral vaccine design and will provide insights into treatments that quiet pathological intestinal inflammation.

Abstract B72: Humanized NSG-Tg(Hu-IL15) mice support preclinical immune-oncology efficacy for testing of NK cell-based immunotherapy

Abstract The JAX® Onco-Hu® platform utilizes humanized mice engrafted with tumors to enable in vivo investigation of the interactions between the human immune system and human cancer. We have shown that humanized NOD-scid IL2Rγ null (NSG) mice bearing patient-derived xenografts (PDX) allow efficacy studies of checkpoint inhibitors. A major avenue of our investigation is to generate humanized mouse models containing a more complete human hematopoietic system and robust innate immune cell population. Nature killer (NK) cells are important players of innate defense against cancerous cells by a number of mechanisms, including antibody-dependent cell-mediated cytotoxicity (ADCC). To overcome limited NK cell development in humanized NSG mice, we have developed NSG-Tg(Hu-IL15) (JAX stock number 030890) mice constitutively expressing human IL15. Following HSC-engraftment of NSG-Tg(Hu-IL15) mice, significantly higher levels of human CD16+CD56+ NK cells are detectable as compared to NSG mice in peripheral blood during the whole course of the study (18 weeks). Levels of circulating human CD45+ cells, CD3+ T cells, CD19+ B cells, and CD33+ myeloid cells are similar between the HSC-engrafted NSG-Tg(Hu-IL15) and NSG mice. Previously we have described that the human NK cells developing in HSC-engrafted NSG-Tg(Hu-IL15) mice are functional and can lyse the NK-sensitive target cells K562 by in vitro cytotoxicity assay. We also showed that NK cells limit the growth of a PDX melanoma xenograft. Here we show that humanized NSG-Tg(Hu-IL15) mice mediate efficient ADCC against Daudi B lymphoma cells in vivo. Administration of anti-human CD20 antibody (rituximab) resulted in significant tumor growth inhibition, in both tumor volume and tumor weight. We observed consistent ADCC efficacy in humanized NSG-Tg (Hu-IL15) mice engrafted with three different HSC donors. Together these data demonstrate that HSC-engrafted NSG-Tg(Hu-IL15) mice support enhanced development of functional human NK cells and that this mouse model enables NK cell-targeted cancer immunotherapy for preclinical testing. Citation Format: Li-Chin Yao, Mingshan Cheng, Leonard D. Shultz, Dale L. Greiner, Michael A. Brehm, James G. Keck. Humanized NSG-Tg(Hu-IL15) mice support preclinical immune-oncology efficacy for testing of NK cell-based immunotherapy [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr B72.

The Methyl-CpG-Binding Protein Mbd2 Regulates Susceptibility to Experimental Colitis via Control of CD11c+ Cells and Colonic Epithelium.

Methyl-CpG-binding domain-2 (Mbd2) acts as an epigenetic regulator of gene expression, by linking DNA methylation to repressive chromatin structure. Although Mbd2 is widely expressed in gastrointestinal immune cells and is implicated in regulating intestinal cancer, anti-helminth responses and colonic inflammation, the Mbd2-expressing cell types that control these responses are incompletely defined. Indeed, epigenetic control of gene expression in cells that regulate intestinal immunity is generally poorly understood, even though such mechanisms may explain the inability of standard genetic approaches to pinpoint the causes of conditions like inflammatory bowel disease. In this study we demonstrate a vital role for Mbd2 in regulating murine colonic inflammation. Mbd2−/− mice displayed dramatically worse pathology than wild type controls during dextran sulfate sodium (DSS) induced colitis, with increased inflammatory (IL-1β+) monocytes. Profiling of mRNA from innate immune and epithelial cell (EC) populations suggested that Mbd2 suppresses inflammation and pathology via control of innate-epithelial cell crosstalk and T cell recruitment. Consequently, restriction of Mbd2 deficiency to CD11c+ dendritic cells and macrophages, or to ECs, resulted in increased DSS colitis severity. Our identification of this dual role for Mbd2 in regulating the inflammatory capacity of both CD11c+ cells and ECs highlights how epigenetic control mechanisms may limit intestinal inflammatory responses.

Mucosal-Associated Invariant T cell in liver diseases.

Mucosal-associated invariant T cells (MAIT cells) are a new population of innate immune cells, which are abundant in the liver and play complex roles in various liver diseases. In this review, we summarize MAIT cells in the liver diseases in recent studies, figure out the role of MAIT cells in various liver disease, including Alcoholic liver disease, Non-alcoholic liver disease, Autoimmune liver diseases, Viral hepatitis and Liver Cancer. Briefly, MAIT cells are involved in anti-bacteria responses in the alcoholic liver diseases. Besides, the activated MAIT cells promote the liver inflammation by secreting inflammatory cytokines and produce regulatory cytokines, which induces anti-inflammatory macrophage polarization. MAIT cells participate in the liver fibrosis via enhancing hepatic stellate cell activation. In viral hepatitis, MAIT cells exhibit a flawed and exhausted phenotype, which results in little effect on controlling the virus and bacteria. In liver cancer, MAIT cells indicate the disease progression and the outcome of therapy. In summary, MAIT cells are attractive biomarkers and therapeutic targets for liver disease.