Function Of Adaptive Immune Cells Research Articles

Effect of exogenous IL-37 on immune cells from a patient carrying a potential IL37 loss-of-function variant: A case study.

Chronic inflammatory or autoimmune diseases are commonly treated with immunosuppressive medication such as NSAIDs, corticosteroids, or antibodies against specific cytokines (TNF, IL-1 IL-17, IL-23, etc.) or signalling cascades (e.g. JAK-STAT inhibitors). Using sequencing data to locate genetic mutations in relevant genes allows the identification of alternative targets in a patient-tailored therapy setting. Interleukin (IL)-37 is an anti-inflammatory cytokine with broad effects on innate and adaptive immune cell function. Dysfunctional IL-37 expression or signalling is linked to various autoinflammatory disorders. The administration of recombinant IL-37 to hyperinflammatory patients that are non-responsive to standard treatment bears the potential to alleviate symptoms. In this case study, the (hyper)responsiveness of immune cell subsets was investigated in a single patient with a seronegative autoimmune disorder who carries a heterozygous stop-gain variant in IL37 (IL37 Chr2(GRCh37):g.113670640G>A NM_014439.3:c.51G>A p.(Trp17*)). As the patient has been non-responsive to blockage of TNF or IL-1 by Etanercept or Anakinra, respectively, additional in-vitro experiments were set out to elucidate whether treatment with recombinant IL-37 could normalise observed immune cell functions. Characterisation of immune cell function showed no elevated overall production of acute-phase pro-inflammatory cytokines by patient PBMCs and neutrophils at baseline or upon stimulation. T-cell responses were elevated, as was the metabolic activity and IL-1Ra production of PBMCs at baseline. The identified stop-gain variant in IL37 does not result in the absence of the protein in circulation. In line with this, treatment with recombinant IL-37 did overall not dampen immune responses with the exception of the complete suppression of IL-17. The heterozygous stop-gain variant in IL37 (IL37 NM_014439.3:c.51G>A p.(Trp17*)) is not of functional relevance as we observed no clear pro-inflammatory phenotype in immune cells of a patient carrying this variant.

The effects of progesterone on immune cellular function at the maternal-fetal interface and in maternal circulation

Progesterone is a sex steroid hormone that plays a critical role in the establishment and maintenance of pregnancy. This hormone drives numerous maternal physiological adaptations to ensure the continuation of pregnancy and to facilitate fetal growth, including broad and potent modulation of the maternal immune system to promote maternal-fetal tolerance. In this brief review, we provide an overview of the immunomodulatory functions of progesterone in the decidua, placenta, myometrium, and maternal circulation during pregnancy. Specifically, we summarize current evidence of the regulated functions of innate and adaptive immune cells induced by progesterone and its downstream effector molecules in these compartments, including observations in human pregnancy and in animal models. Our review highlights the gaps in knowledge of interactions between progesterone and maternal cellular immunity that may direct future research.

Immune response to arbovirus infection in obesity.

Obesity is a global health problem that affects 650 million people worldwide and leads to diverse changes in host immunity. Individuals with obesity experience an increase in the size and the number of adipocytes, which function as an endocrine organ and release various adipocytokines such as leptin and adiponectin that exert wide ranging effects on other cells. In individuals with obesity, macrophages account for up to 40% of adipose tissue (AT) cells, three times more than in adipose tissue (10%) of healthy weight individuals and secrete several cytokines and chemokines such as interleukin (IL)-1β, chemokine C-C ligand (CCL)-2, IL-6, CCL5, and tumor necrosis factor (TNF)-α, leading to the development of inflammation. Overall, obesity-derived cytokines strongly affect immune responses and make patients with obesity more prone to severe symptoms than patients with a healthy weight. Several epidemiological studies reported a strong association between obesity and severe arthropod-borne virus (arbovirus) infections such as dengue virus (DENV), chikungunya virus (CHIKV), West Nile virus (WNV), and Sindbis virus (SINV). Recently, experimental investigations found that DENV, WNV, CHIKV and Mayaro virus (MAYV) infections cause worsened disease outcomes in infected diet induced obese (DIO) mice groups compared to infected healthy-weight animals. The mechanisms leading to higher susceptibility to severe infections in individuals with obesity remain unknown, though a better understanding of the causes will help scientists and clinicians develop host directed therapies to treat severe disease. In this review article, we summarize the effects of obesity on the host immune response in the context of arboviral infections. We have outlined that obesity makes the host more susceptible to infectious agents, likely by disrupting the functions of innate and adaptive immune cells. We have also discussed the immune response of DIO mouse models against some important arboviruses such as CHIKV, MAYV, DENV, and WNV. We can speculate that obesity-induced disruption of innate and adaptive immune cell function in arboviral infections ultimately affects the course of arboviral disease. Therefore, further studies are needed to explore the cellular and molecular aspects of immunity that are compromised in obesity during arboviral infections or vaccination, which will be helpful in developing specific therapeutic/prophylactic interventions to prevent immunopathology and disease progression in individuals with obesity.

Opportunities for Nitric Oxide in Potentiating Cancer Immunotherapy.

Despite nearly 30 years of development and recent highlights of nitric oxide (NO) donors and NO delivery systems in anticancer therapy, the limited understanding of exogenous NO's effects on the immune system has prevented their advancement into clinical use. In particular, the effects of exogenously delivered NO differing from that of endogenous NO has obscured how the potential and functions of NO in anticancer therapy may be estimated and exploited despite the accumulating evidence of NO's cancer therapy-potentiating effects on the immune system. After introducing their fundamentals and characteristics, this review discusses the current mechanistic understanding of NO donors and delivery systems in modulating the immunogenicity of cancer cells as well as the differentiation and functions of innate and adaptive immune cells. Lastly, the potential for the complex modulatory effects of NO with the immune system to be leveraged for therapeutic applications is discussed in the context of recent advancements in the implementation of NO delivery systems for anticancer immunotherapy applications. SIGNIFICANCE STATEMENT: Despite a 30-year history and recent highlights of nitric oxide (NO) donors and delivery systems as anticancer therapeutics, their clinical translation has been limited. Increasing evidence of the complex interactions between NO and the immune system has revealed both the potential and hurdles in their clinical translation. This review summarizes the effects of exogenous NO on cancer and immune cells in vitro and elaborates these effects in the context of recent reports exploiting NO delivery systems in vivo in cancer therapy applications.

Pregnancy imparts distinct systemic adaptive immune function.

Pregnancy represents a state of systemic immune activation that is primarily driven by alterations in circulating innate immune cells. Recent studies have suggested that cellular adaptive immune components, T cells and B cells, also undergo changes throughout gestation. However, the phenotypes and functions of such adaptive immune cells are poorly understood. Herein, we utilized high-dimensional flow cytometry and functional assays to characterize T-cell and B-cell responses in pregnant and non-pregnant women. Peripheral blood mononuclear cells from pregnant (n=20) and non-pregnant (n=25) women were used for phenotyping of T-cell and B-cell subsets. T-cell proliferation and B-cell activation were assessed by flow cytometry after in vitro stimulation, and lymphocyte cytotoxicity was evaluated by using a cell-based assay. Statistical comparisons were performed with linear mixed-effects models. Pregnancy was associated with modestly enhanced basal activation of peripheral CD4+ T cells. Both CD4+ and CD8+ T cells from pregnant women showed increased activation-induced proliferation; yet, a reduced proportion of these cells expressed activation markers compared to non-pregnant women. There were no differences in peripheral lymphocyte cytotoxicity between study groups. A greater proportion of B cells from pregnant women displayed memory-like and activated phenotypes, and such cells exhibited higher activation following stimulation. Maternal circulating T cells and B cells display distinct responses during pregnancy. The former may reflect the unique capacity of T cells to respond to potential threats without undergoing aberrant activation, thereby preventing systemic inflammatory responses that can lead to adverse perinatal consequences.

Innate lymphocytes: Role in alcohol-induced immune dysfunction.

Alcohol use is known to alter the function of both innate and adaptive immune cells, such as neutrophils, macrophages, B cells, and T cells. Immune dysfunction has been associated with alcohol-induced end-organ damage. The role of innate lymphocytes in alcohol-associated pathogenesis has become a focus of research, as liver-resident natural killer (NK) cells were found to play an important role in alcohol-associated liver damage pathogenesis. Innate lymphocytes play a critical role in immunity and homeostasis; they are necessary for an optimal host response against insults including infections and cancer. However, the role of innate lymphocytes, including NK cells, natural killer T (NKT) cells, mucosal associated invariant T (MAIT) cells, gamma delta T cells, and innate lymphoid cells (ILCs) type 1–3, remains ill-defined in the context of alcohol-induced end-organ damage. Innate-like B lymphocytes including marginal zone B cells and B-1 cells have also been identified; however, this review will address the effects of alcohol misuse on innate T lymphocytes, as well as the consequences of innate T-lymphocyte dysfunction on alcohol-induced tissue damage.

Store‐operated calcium entry controls innate and adaptive immune cell function in inflammatory bowel disease

Inflammatory bowel disease (IBD) is characterized by dysregulated intestinal immune responses. Using mass cytometry (CyTOF) to analyze the immune cell composition in the lamina propria (LP) of patients with ulcerative colitis (UC) and Crohn's disease (CD), we observed an enrichment of CD4+ effector T cells producing IL‐17A and TNF, CD8+ T cells producing IFNγ, T regulatory (Treg) cells, and innate lymphoid cells (ILC). The function of these immune cells is regulated by store‐operated Ca2+ entry (SOCE), which results from the opening of Ca2+ release‐activated Ca2+ (CRAC) channels formed by ORAI and STIM proteins. We observed that the pharmacologic inhibition of SOCE attenuated the production of proinflammatory cytokines including IL‐2, IL‐4, IL‐6, IL‐17A, TNF, and IFNγ by human colonic T cells and ILCs, reduced the production of IL‐6 by B cells and the production of IFNγ by myeloid cells, but had no effect on the viability, differentiation, and function of intestinal epithelial cells. T cell‐specific deletion of CRAC channel genes in mice showed that Orai1, Stim1, and Stim2‐deficient T cells have quantitatively distinct defects in SOCE, which correlate with gradually more pronounced impairment of cytokine production by Th1 and Th17 cells and the severity of IBD. Moreover, the pharmacologic inhibition of SOCE with a selective CRAC channel inhibitor attenuated IBD severity and colitogenic T cell function in mice. Our data indicate that SOCE inhibition may be a suitable new approach for the treatment of IBD.

Discovery and pre-clinical characterization of a selective PI3Kδ inhibitor, LL-00071210 in rheumatoid arthritis

PI3Kδ plays a critical role in adaptive immune cell activation and function. Suppression of PI3Kδ has been shown to counter excessive triggering of immune responses which has led to delineating the role of this isoform in the pathophysiology of autoimmune disorders. In the current study, we have described preclinical characterization of PI3Kδ specific inhibitor LL-00071210 in various rheumatoid arthritis models. LL-00071210 displayed excellent in vitro potency in biochemical and cellular assay against PI3Kδ with IC50 values of 24.6 nM and 9.4 nM, respectively. LL-00071210 showed higher selectivity over PI3Kγ and PI3Kβ as compared to available PI3K inhibitors. LL-00071210 had good stability in liver microsomes and plasma across species and showed low clearance, low-to-moderate Vss, with bioavailability of >50% in preclinical species. LL-00071210 demonstrated excellent in vivo efficacy in adjuvant-induced and collagen-induced arthritis models. Co-administration of LL-00071210 and methotrexate at subtherapeutic dose regimen in collagen induced arthritis model led to additive effects, indicating the combination potential of LL-00071210 along with available disease modifying anti-rheumatic drugs (DMARD). In conclusion, we have described a specific PI3Kδ inhibitor with ∼100-fold selectivity over other PI3K isoforms. LL-00071210 has good drug-like properties and thus warrants testing in the clinic for the treatment of autoimmune diseases.

Metabolic syndrome enhances viral disease severity and reduces vaccine efficacy in mice

Abstract Metabolic syndrome (MetS) is a cluster of conditions linked by chronic inflammation that increase the risk for comorbidities. Currently, 1/3 of United States adults have MetS. Globally, obesity rates have tripled since 1975, which is notable since it is a criterium used to diagnose MetS. MetS patients show higher mortality post-SARS-CoV-2 infection and poor vaccination outcomes following influenza virus vaccination when compared to metabolically healthy humans. However, the mechanisms driving MetS-induced immune dysfunction are unknown. Based on previously published work, we hypothesize that MetS-associated chronic inflammation alters programming of adaptive immune cells critical for viral control, thus enhancing disease severity and reducing vaccine efficacy. To challenge this, we use West Nile virus and SARS-CoV-2 in MetS murine models. By infecting or vaccinating chow fed wild type (WT) and high fat diet induced MetS mice, we compared immune responses over time. Our results indicate that MetS mice have higher mortality post infection, heightened viral titers, severe organ pathology, dysfunctional T and B cell responses and reduced neutralizing antibody efficacy when compared to WT mice. Further, MetS alters antibody and T cell responses post-vaccination, rendering vaccination insufficient for protecting against severe viral disease. Our results imply that MetS enhances viral disease severity and reduces vaccine efficacy. Ongoing studies in our lab are focused on determining the mechanism by which MetS alters adaptive immune cell function, with our data implicating chronic inflammation as an inducer of immune cell epigenetic changes that alter their differentiation landscapes and consequently effector functions. Supported by grants from NIH (R01 12781495) and DoD (USAMRDCPR192269).

Natural Killer Cells in Multiple Sclerosis: Entering the Stage.

Studies investigating the immunopathology of multiple sclerosis (MS) have largely focused on adaptive T and B lymphocytes. However, in recent years there has been an increased interest in the contribution of innate immune cells, amongst which the natural killer (NK) cells. Apart from their canonical role of controlling viral infections, cell stress and malignancies, NK cells are increasingly being recognized for their modulating effect on the adaptive immune system, both in health and autoimmune disease. From different lines of research there is now evidence that NK cells contribute to MS immunopathology. In this review, we provide an overview of studies that have investigated the role of NK cells in the pathogenesis of MS by use of the experimental autoimmune encephalomyelitis (EAE) animal model, MS genetics or through ex vivo and in vitro work into the immunology of MS patients. With the advent of modern hypothesis-free technologies such as single-cell transcriptomics, we are exposing an unexpected NK cell heterogeneity, increasingly blurring the boundaries between adaptive and innate immunity. We conclude that unravelling this heterogeneity, as well as the mechanistic link between innate and adaptive immune cell functions will lay the foundation for the use of NK cells as prognostic tools and therapeutic targets in MS and a myriad of other currently uncurable autoimmune disorders.

The Rising Era of "Immunoporosis": Role of Immune System in the Pathophysiology of Osteoporosis.

Discoveries in the last few years have emphasized the existence of an enormous breadth of communication between bone and the immune system in maintaining skeletal homeostasis. Originally, the discovery of various factors was assigned to the immune system viz. interleukin (IL)-6, IL-10, IL-17, tumor necrosis factor (TNF)-α, receptor activator of nuclear factor kappa B ligand (RANKL), nuclear factor of activated T cells (NFATc1), etc., but now these factors have also been shown to have a significant impact on osteoblasts (OBs) and osteoclasts (OCs) biology. These discoveries led to an alteration in the approach for the treatment of several bone pathologies including osteoporosis. Osteoporosis is an inflammatory bone anomaly affecting more than 500 million people globally. In 2018, to highlight the importance of the immune system in the pathophysiology of osteoporosis, our group coined the term “immunoporosis”. In the present review, we exhaustively revisit the characteristics, mechanism of action, and function of both innate and adaptive immune cells with the goal of understanding the potential of immune cells in osteoporosis. We also highlight the Immunoporotic role of gut microbiota (GM) for the treatment and management of osteoporosis. Importantly, we further discuss whether an immune cell-based strategy to treat and manage osteoporosis is feasible and relevant in clinical settings.

MTOR-Mediated Regulation of Immune Responses in Cancer and Tumor Microenvironment.

The mechanistic/mammalian target of rapamycin (mTOR) is a downstream mediator in the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathways, which plays a pivotal role in regulating numerous cellular functions including cell growth, proliferation, survival, and metabolism by integrating a variety of extracellular and intracellular signals in the tumor microenvironment (TME). Dysregulation of the mTOR pathway is frequently reported in many types of human tumors, and targeting the PI3K/Akt/mTOR signaling pathway has been considered an attractive potential therapeutic target in cancer. The PI3K/Akt/mTOR signaling transduction pathway is important not only in the development and progression of cancers but also for its critical regulatory role in the tumor microenvironment. Immunologically, mTOR is emerging as a key regulator of immune responses. The mTOR signaling pathway plays an essential regulatory role in the differentiation and function of both innate and adaptive immune cells. Considering the central role of mTOR in metabolic and translational reprogramming, it can affect tumor-associated immune cells to undergo phenotypic and functional reprogramming in TME. The mTOR-mediated inflammatory response can also promote the recruitment of immune cells to TME, resulting in exerting the anti-tumor functions or promoting cancer cell growth, progression, and metastasis. Thus, deregulated mTOR signaling in cancer can modulate the TME, thereby affecting the tumor immune microenvironment. Here, we review the current knowledge regarding the crucial role of the PI3K/Akt/mTOR pathway in controlling and shaping the immune responses in TME.

P096 Store-Operated Calcium Entry Controls Innate and Adaptive Immune Cell Function in Inflammatory Bowel Disease

Abstract Background Inflammatory bowel disease (IBD) represents a major clinical challenge in need of new treatment modalities to improve patient care. Store-operated calcium entry (SOCE) is the predominant calcium influx pathway in T cells, regulating many of their functional properties. However, it is currently unknown whether the pharmacologic inhibition of SOCE is a suitable drug target in IBD. Therefore, we aimed to investigate the effects of SOCE inhibitors (SOCEi) on lymphocytes and epithelial cells isolated from IBD patients. Methods Peripheral blood mononuclear cells (PBMC), lamina propria lymphocytes (LPMCs) and epithelial cells were isolated from IBD patients undergoing colon resection. LPMCs or PBMCs were ex-vivo stimulated with Ionomycin/PMA ± SOCEi and subsequently stained with a panel of 37 immunological markers for mass cytometry acquisition. Ca2+ influx measurements were performed in order to assess the metabolic status of immune (PBMCs and LPMCs) and epithelial cells after SOCE blockade. Finally, murine models of colitis were used in order to investigate the effects of SOCE blockade on the induction of intestinal inflammation in-vivo. Results Data on B, T, NK, and myeloid cells revealed that treatment with SOCEi caused a dose-dependent inhibition of Ca2+ signaling in human gut-resident lymphocytes and PBMCs. The inhibition of SOCE attenuated the production of pathogenic cytokines including IL-2, IL-4, IL-6, IL-17, TNF-α and IFNγ by colonic T cells and ILCs, reduced the activation of B cells and the production of IL-6 by myeloid cells, without affecting the viability of primary human epithelial cells. Remarkably, mouse models of transfer colitis, in which SOCE signaling components have been blocked, revealed that SOCE is required for the induction of intestinal inflammation in-vivo. Conclusion Our data revealed for the first time that the cytokine production and the activation of several immune cell subtypes can be modulated by SOCE blockade in human intestinal inflammation, identifying SOCE as a novel therapeutic target in colitis.

The Modulatory Effects and Targets Prediction of Herbal Medicines or Phytochemicals on Cancer Immunosurveillance

Cancer is a main life-threatening disease worldwide. Due to the adverse effects of conventional chemotherapies and radiotherapies, immunotherapy has emerged as a potent strategy to treat cancer. In cancer immunotherapy, cancer immune surveillance plays a crucial role in the cancer process, which contains various effector cells from innate and adaptive immunity. This review summarized the functions of innate and adaptive immune cells in cancer immunosurveillance and their main reported targets. Moreover, the potential targets about the modulatory effects of cancer immunosurveillance were predicted using network-based target analysis, with total predicted pathways not only reporting previously reported pathways, but also putative signaling pathways pending for investigation. In addition, the potential use of herbal medicines and their phytochemicals in the modulation of cancer immunosurveillance were also discussed. Taken together, this review paper aims to provide scientific insight into further drug development, particularly herbs, phytochemicals, and TCM formulae, in the modulatory effects of cancer immunosurveillance.

Atlas of circulating immune cells in Kawasaki disease

Increasing evidence shows that the pathogenesis of Kawasaki disease (KD) is caused by abnormal and unbalanced innate and adaptive immune responses. However, the changes in and functions of adaptive immune cells in the peripheral blood of subjects with KD remain controversial. In this study, three different methods, CIBERSORT, Immune Cell Abundance Identifier (ImmuCellAI), and immune cell markers, were used to evaluate the proportions and abundances of immune cells in eight KD datasets (GSE9863, GSE9864, GSE18606, GSE63881, GSE68004, GSE73461, GSE73463, and GSE64486; a total of 1,251 samples). Compared with those in normal controls and convalescent KD samples, the proportions and abundances of innate immune cells such as neutrophils, monocytes, and macrophages in acute KD peripheral blood samples were significantly increased, while those of adaptive immune cells such as B and T cells were significantly decreased. The change tendencies of these immune cells were similar to those observed in other febrile illnesses but were more significant. However, in the coronary artery tissues of patients with convalescent KD, adaptive immune cells, especially B cells and CD8+ T cell subsets, were significantly increased. This result suggests that adaptive immune cells can be selectively recruited from peripheral blood into the coronary arteries. In addition, we found that elevated neutrophils in peripheral blood could be used as a biomarker to assist in the differential diagnosis of KD, but we did not find immune cells that could accurately predict intravenousimmunoglobulin (IVIG) responses in multiple datasets.

Interferon-γ-Induced Myeloid-Derived Suppressor Cells Aggravate Kidney Ischemia-Reperfusion Injury by Regulating Innate Immune Cells

Objective: Myeloid-derived suppressor cells (MDSCs) are heterogeneous cells which can suppress T-cell functionality. Herein, we evaluated the functional importance of MDSCs in the context of kidney ischemia-reperfusion injury (IRI) and explored their ability to regulate innate and adaptive immune cell function in this context. Methods: The differentiation of MDSCs was induced in vitro by treating cells with GM-CSF and interferon (IFN)-γ. In a murine model of renal IRI, serum creatinine and blood urea nitrogen values were measured to monitor kidney function, while histopathological and immunohistochemical approaches were used to assess kidney injury severity. In addition, flow cytometry was employed to assess the phenotypes and apoptosis of kidney cells in these mice. Results: MDSCs induced by treatment with GM-CSF + IFN-γ could suppress T-cell functionality in vitro. The adoptive transfer of these MDSCs into an IRI mouse model system enhanced kidney damage and impaired renal function following the recruitment of these cells to renal tissues in these mice. Following such adoptive transfer, the relative frequency of MDSCs with a CD11b⁺Ly6G⁻Ly6C^high monocytic-MDSC phenotype decreased, whereas cells with a CD11b⁺Ly6G⁺Ly6C^low polymorphonuclear-MDSC phenotype become more prevalent within kidney tissues following IRI. Adoptive transfer also coincided with increased frequencies of macrophages and dendritic cells (DCs) in the kidney tissues. This suggested that M-MDSCs contributed to early-stage renal IRI damage by differentiating into these deleterious cell types. However, MDSC-induced suppression of CD4⁺ and CD8⁺ T-cell infiltration was not sufficient to prevent the deterioration of renal function in these mice. Conclusions: Herein, we successfully developed a protocol wherein MDSCs were differentiated in vitro through combination GM-CSF/IFN-γ treatment. When these MDSCs were subsequently adoptively transferred into a murine model of renal IRI, they aggravated kidney damage, likely owing to the differentiation of M-MDSCs into deleterious macrophages and DCs.

Early Leukocyte Responses in Ex-Vivo Models of Healing and Non-Healing Human Leishmania (Viannia) panamensis Infections.

Early host-pathogen interactions drive the host response and shape the outcome of natural infections caused by intracellular microorganisms. These interactions involve a number of immune and non-immune cells and tissues, along with an assortment of host and pathogen-derived molecules. Our current knowledge has been predominantly derived from research on the relationships between the pathogens and the invaded host cell(s), limiting our understanding of how microbes elicit and modulate immunological responses at the organismal level. In this study, we explored the early host determinants of healing and non-healing responses in human cutaneous leishmaniasis (CL) caused by Leishmania (Viannia) panamensis. We performed a comparative transcriptomic profiling of peripheral blood mononuclear cells from healthy donors (PBMCs, n=3) exposed to promastigotes isolated from patients with chronic (CHR, n=3) or self-healing (SH, n=3) CL, and compared these to human macrophage responses. Transcriptomes of L. V. panamensis-infected PBMCs showed enrichment of functional gene categories derived from innate as well as adaptive immune cells signatures, demonstrating that Leishmania modulates adaptive immune cell functions as early as after 24h post interaction with PBMCs from previously unexposed healthy individuals. Among differentially expressed PBMC genes, four broad categories were commonly modulated by SH and CHR strains: cell cycle/proliferation/differentiation, metabolism of macromolecules, immune signaling and vesicle trafficking/transport; the first two were predominantly downregulated, and the latter upregulated in SH and CHR as compared to uninfected samples. Type I IFN signaling genes were uniquely up-regulated in PBMCs infected with CHR strains, while genes involved in the immunological synapse were uniquely downregulated in SH infections. Similarly, pro-inflammatory response genes were upregulated in isolated macrophages infected with CHR strains. Our data demonstrate that early responses during Leishmania infection extend beyond innate cell and/or phagocytic host cell functions, opening new frontiers in our understanding of the triggers and drivers of human CL.

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.

Gut Microbiome and Metabolites in Systemic Lupus Erythematosus: Link, Mechanisms and Intervention.

Systemic lupus erythematosus (SLE), often considered the prototype of autoimmune diseases, is characterized by over-activation of the autoimmune system with abnormal functions of innate and adaptive immune cells and the production of a large number of autoantibodies against nuclear components. Given the highly complex and heterogeneous nature of SLE, the pathogenesis of this disease remains incompletely understood and is presumed to involve both genetic and environmental factors. Currently, disturbance of the gut microbiota has emerged as a novel player involved in the pathogenesis of SLE. With in-depth research, the understanding of the intestinal bacteria-host interaction in SLE is much more comprehensive. Recent years have also seen an increase in metabolomics studies in SLE with the attempt to identify potential biomarkers for diagnosis or disease activity monitoring. An intricate relationship between gut microbiome changes and metabolic alterations could help explain the mechanisms by which gut bacteria play roles in the pathogenesis of SLE. Here, we review the role of microbiota dysbiosis in the aetiology of SLE and how intestinal microbiota interact with the host metabolism axis. A proposed treatment strategy for SLE based on gut microbiome (GM) regulation is also discussed in this review. Increasing our understanding of gut microbiota and their function in lupus will provide us with novel opportunities to develop effective and precise diagnostic strategies and to explore potential microbiota-based treatments for patients with lupus.

OTME-6. Deep sequencing reveals heterogeneity of brain metastasis-associated macrophages and microglia and uncovers their cell type-specific functions within the tumor microenvironment

Macrophages represent a highly plastic cell type,indispensable for tissue and organ homeostasis, as well as innate immunity. Basic and translational research attributed tumor-promoting functions to macrophages, and their presence is often associated to poor patient prognosis and therapy resistance. While brain-resident macrophages, the so-called microglia (MG), represent the major immune cell type in the parenchyma under normal conditions, primary and metastatic brain tumors induce the recruitment of different immune cell types from the periphery, including monocyte-derived macrophages (MDM). Controversy remained about the redundancy of disease-associated molecular signatures and functions. The identification of markers that reliably distinguish brain-resident from blood-borne tumor-associated macrophages (TAMs) allowed the interrogation of molecular traits of different TAM populations in mouse and human brain tumors.Using RNA-Seq, we demonstrated that TAMs rapidly acquire disease-associated transcriptional programs upon initial tumor infiltration, while gene expression remained stable during different stages of BrM progression. Across different BrM models, disease-associated transcriptional changes revealed lineage-specific, non-redundant functions of TAM populations, which was further reflected by cell type-specific occupation of different niches within the BrM microenvironment. Furthermore, we observed dose- and cell type-specific immune modulatory effects of whole brain radiotherapy on myeloid cells in BrM leading to a transient loss of disease-associated transcriptional programs predominately in blood-borne myeloid populations. This effect can at least in part be attributed to a replenishment of the recruited macrophage pool. This observation was further supported by scRNA-Seq analyses revealing higher heterogeneity of TAM-MDM compared to TAM-MG under treatment-naïve conditions and in response to radiotherapy.Together, our results point towards the phenotypic plasticity of TAMs, especially MDMs, and the contribution of each compartment in instigating cancer-associated inflammation or the establishment of an immuno-suppressive TME. While TAM-MG exert functions related to pro-inflammatory responses, TAM-MDM are rather involved in tissue repair and regulation of adaptive immune cell functions.