Dendritic Cells Subpopulations Research Articles

Targeting the NLRP3 inflammasome reduces inflammation in hidradenitis suppurativa skin.

Treatment for the debilitating disease hidradenitis suppurativa (HS) is inadequate in many patients. Despite an incidence of approximately 1%, HS is often underrecognized and underdiagnosed and is associated with a high morbidity and poor quality of life. A better understanding of its pathogenesis is required to design new therapeutic strategies. In this study we employed single cell RNA sequencing to analyse gene expression in immune cells isolated from involved HS skin compared with healthy skin. Flow cytometry was used to quantify the absolute numbers of the main immune populations. Secretion of inflammatory mediators from skin explant cultures was measured using multiplex assays and ELISA. Single cell RNA sequencing analysis identified a significant enrichment in the frequency of plasma cells, Th17 cells and dendritic cell subsets in HS skin, and the immune transcriptome was distinct and much more heterogenous when compared with healthy skin. Flow cytometry revealed significantly increased numbers of T cells, B cells, neutrophils, dermal macrophages, and dendritic cells into involved HS skin. Genes and pathways associated with Th17 cells, IL-17, IL-1β, and the NLRP3 inflammasome were enhanced in HS skin, particularly in samples with a high inflammatory load. Inflammasome constituent genes principally mapped to Langerhans cells and a subpopulation of dendritic cells. The secretome of HS skin explants contained significantly increased concentrations of inflammatory mediators including IL-1β and IL-17A, and culture with an NLRP3 inflammasome inhibitor significantly reduced the secretion of these as well as other key mediators of inflammation. These data provide a rationale for targeting the NLRP3 inflammasome in HS using small molecule inhibitors which are currently being tested for other indications.

Identifying and targeting a subpopulation of dendritic cells with enhanced activation of adaptive responses - identifying first responders.

Abstract Dendritic cell (DC) activation via pathogen-associated molecular patterns (PAMPs) is critical for antigen presentation and development of adaptive immune responses, but the stochastic distribution of DC responses to PAMP signaling, especially during the initial stages of immune activation, is poorly understood. In this study, we isolate a unique DC subpopulation via preferential phagocytosis of microparticles (MPs) and characterize this subpopulation of “first responders” (FRs). We present results that show these cells (1) can be isolated and studied via both increased accumulation of the micron-sized particles and combinations of cell surface markers, (2) show increased responses to PAMPs, (3) facilitate adaptive immune responses by providing the initial paracrine signaling, and (4) can be selectively targeted by vaccines to modulate both antibody and T cell responses in vivo. This study presents insights into a temporally controlled, distinctive cell population that influences downstream immune responses. Furthermore, it demonstrates potential for improving vaccine designs via FR targeting. 7U01AI124286-03, 5 F32 AI147517

Abstract PD4-05: PD4-05 Integrated multi-cohort profiling identifies CCL19+ dendritic cells to potentiate immunotherapy efficacy in triple-negative breast cancer

Abstract Background: Immune checkpoint inhibitors (ICIs) targeting the PD-1/PD-L1 axis have emerged as constituting a new pillar for breast cancer; however, they benefit only a subset of patients, and predictive biomarkers are urgently needed. While dendritic cells (DCs) are essential for the orchestration of antitumor immune response, the clinical value of DCs in breast cancer immunotherapy remains unclear. An improved understanding of the functional diversity of DC subsets, as well as their relationship with ICI response, would eventually improve the efficacy of ICIs in breast cancer patients. Objective: We sought to comprehensively characterize DC heterogeneity within the tumor microenvironment, identify distinct DC subsets associated with the response to ICIs, and define clinically applicable predictive biomarkers for ICI therapy. Methods: We performed a comprehensive single-cell RNA sequencing (scRNA-seq) analysis of 53 breast tumors receiving ICIs or chemotherapy in two retrospective studies (NCT03197389 and GSE169246) to identify specific DC populations associated with ICI responsiveness. Next, we harnessed multiplex immunohistochemistry (n = 186), multiparametric flow cytometry of fresh tissues (n = 87), large consecutive transcriptomic datasets (The Cancer Genome Atlas [TCGA] and Fudan University Shanghai Cancer Center [FUSCC]), and in vivo experiments to illustrate the molecular portraits and clinical relevance of the identified DC subsets. Additionally, except for the two scRNA-seq datasets, we leveraged another four independent cohorts (NCT03805399, NCT04613674, NCT04129996, GSE124821) and assessed the clinical utility of the established clinically applicable biomarkers derived from prior analyses to predict response following treatment with ICIs or chemotherapy. Results: By obtaining single-cell transcriptome data of 1,955 high-quality DCs, we identified five distinct DC subpopulations (CLEC9A+, CD1A+, CLEC10A+, CCL19+, and LILRA4+). We then illustrated that a specific CCL19+ DC population, but not whole DCs or other subsets, was associated with ICI responsiveness, particularly in triple-negative breast cancer (TNBC). Mechanistically, a potent CD8+ T-cell response was unleashed, rendering tumors susceptible to PD-1 blockade in vivo and confirming their putative immunomodulatory capacity. This phenomenon was only observed in CCL19+ DCs but not in CCL19- DCs, indicating CCL19 as a specific marker and could reflect the infiltration and functional phenotype of CCL19+ DCs in breast tumors. Finally, by integrating six independent ICI therapy cohorts, we demonstrated that baseline CCL19 in both tumor and blood could predict better response and survival in TNBC patients receiving ICIs, but not so for chemotherapy. Conclusions: Our results provide important insights into the relationship between the clinical outcome of ICIs and DC heterogeneity at single-cell resolution, support the development of therapies modulating CCL19+ DCs to trigger antitumor CD8+ T-cell immunity, and suggest baseline CCL19 levels as a noninvasive predictive biomarker for patients receiving ICIs, that are potentially applicable in the clinic. In light of these results, we suggest CCL19+ DC modulation as a possible precision immunotherapy approach for cancer patients. Citation Format: Song-Yang Wu, Si-Wei Zhang, Ding Ma, Xi Jin, Yi-Zhou Jiang, Zhi-Ming Shao. PD4-05 Integrated multi-cohort profiling identifies CCL19+ dendritic cells to potentiate immunotherapy efficacy in triple-negative breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD4-05.

A Bidirectional Single-Cell Migration and Retrieval Chip for Quantitative Study of Dendritic Cell Migration.

Dendritic cell (DC) migration is a fundamental step during execution of its adaptive immunity functions. Studying DC migration characteristics is critical for development of DC-dependent allergy treatments, vaccines, and cancer immunotherapies. Here, a microfluidics-based single-cell migration platform is described that enables high-throughput and precise bidirectional cell migration assays. It also allows selective retrieval of cell subpopulations that have different migratory potentials. Using this microfluidic platform, DC migration is investigated in response to different chemoattractants and inhibitors, quantitatively describe DC migration patterns and retrieve DC subpopulations of different migratory potentials for differential gene expression analysis. This platform opens an avenue for precise characterization of cell migration and potential discovery of therapeutic modulators.

Distinct and dynamic activation profiles of circulating dendritic cells and monocytes in mild COVID-19 and after yellow fever vaccination.

Dysregulation of the myeloid cell compartment is a feature of severe disease in hospitalized COVID-19 patients. Here, we investigated the response of circulating dendritic cell (DC) and monocyte subpopulations in SARS-CoV-2 infected outpatients with mild disease and compared it to the response of healthy individuals to yellow fever vaccine virus YF17D as a model of a well-coordinated response to viral infection. In SARS-CoV-2-infected outpatients circulating DCs were persistently reduced for several weeks whereas after YF17D vaccination DC numbers were decreased temporarily and rapidly replenished by increased proliferation until 14 days after vaccination. The majority of COVID-19 outpatients showed high expression of CD86 and PD-L1 in monocytes and DCs early on, resembling the dynamic after YF17D vaccination. In a subgroup of patients, low CD86 and high PD-L1 expression were detected in monocytes and DCs coinciding with symptoms, higher age, and lower lymphocyte counts. This phenotype was similar to that observed in severely ill COVID-19 patients, but less pronounced. Thus, prolonged reduction and dysregulated activation of blood DCs and monocytes were seen in a subgroup of symptomatic non-hospitalized COVID-19 patients while a transient coordinated activation was characteristic for the majority of patients with mild COVID-19 and the response to YF17D vaccination.

Isolating and targeting a highly active, stochastic dendritic cell subpopulation for improved immune responses.

Dendritic cell (DC) activation via pathogen-associated molecular patterns (PAMPs) is critical for antigen presentation and development of adaptive immune responses, but the stochastic distribution of DC responses to PAMP signaling, especially during the initial stages of immune activation, is poorly understood. In this study, we isolate a unique DC subpopulation via preferential phagocytosis of microparticles (MPs) and characterize this subpopulation of "first responders" (FRs). We present results that show these cells (1) can be isolated and studied via both increased accumulation of the micron-sized particles and combinations of cell surface markers, (2) show increased responses to PAMPs, (3) facilitate adaptive immune responses by providing the initial paracrine signaling, and (4) can be selectively targeted by vaccines to modulate both antibody and Tcell responses invivo. This study presents insights into a temporally controlled, distinctive cell population that influences downstream immune responses. Furthermore, it demonstrates potential for improving vaccine designs via FR targeting.

GM-CSF-activated human dendritic cells promote type 1 T follicular helper cell polarization in a CD40-dependent manner.

T follicular helper (Tfh) cells regulate humoral responses and present a marked phenotypic and functional diversity. Type 1 Tfh (Tfh1) cells were recently identified and associated with disease severity in infection and autoimmune diseases. The cellular and molecular requirements to induce human Tfh1 differentiation are not known. Here, using single-cell RNA sequencing (scRNAseq) and protein validation, we report that human blood CD1c+ dendritic cells (DCs) activated by GM-CSF (also known as CSF2) drive the differentiation of naive CD4+ T cells into Tfh1 cells. These Tfh1 cells displayed typical Tfh molecular features, including high levels of PD-1 (encoded by PDCD1), CXCR5 and ICOS. They co-expressed BCL6 and TBET (encoded by TBX21), and secreted large amounts of IL-21 and IFN-γ (encoded by IFNG). Mechanistically, GM-CSF triggered the emergence of two DC sub-populations defined by their expression of CD40 and ICOS ligand (ICOS-L), presenting distinct phenotypes, morphologies, transcriptomic signatures and functions. CD40High ICOS-LLow DCs efficiently induced Tfh1 differentiation in a CD40-dependent manner. In patients with mild COVID-19 or latent Mycobacterium tuberculosis infection, Tfh1 cells were positively correlated with a CD40High ICOS-LLow DC signature in scRNAseq of peripheral blood mononuclear cells or blood transcriptomics, respectively. Our study uncovered a novel CD40-dependent Tfh1 axis with potential physiopathological relevance to infection. This article has an associated First Person interview with the first author of the paper.

CXCR6 expressing T cells: Functions and role in the control of tumors

CXCR6 is a receptor for the chemokine CXCL16, which exists as a membrane or soluble form. CXCR6 is a marker for resident memory T (TRM) cells that plays a role in immunosurveillance through their interaction with epithelial cells. The interaction of CXCR6 with CXCL16 expressed at the membrane of certain subpopulations of intratumor dendritic cells (DC) called DC3, ideally positions these CXCR6+ T cells to receive a proliferation signal from IL-15 also presented by DC3. Mice deficient in cxcr6 or blocking the interaction of CXCR6 with its ligand, experience a poorer control of tumor proliferation by CD8+ T cells, but also by NKT cells especially in the liver. Intranasal vaccination induces CXCL16 production in the lungs and is associated with infiltration by TRM expressing CXCR6, which are then required for the efficacy of anti-tumor vaccination. Therapeutically, the addition of CXCR6 to specific CAR-T cells enhances their intratumoral accumulation and prolongs survival in animal models of pancreatic, ovarian and lung cancer. Finally, CXCR6 is part of immunological signatures that predict response to immunotherapy based on anti-PD-(L)1 in various cancers. In contrast, a protumoral role of CXCR6+T cells has also been reported mainly in Non-alcoholic steatohepatitis (NASH) due to a non-antigen specific mechanism. The targeting and amplification of antigen-specific TRM expressing CXCR6 and its potential use as a biomarker of response to immunotherapy opens new perspectives in cancer treatment.

Longitudinal Assessment of Multiple Immunological and Inflammatory Parameters during Successful DAA Therapy in HCV Monoinfected and HIV/HCV Coinfected Subjects.

In the direct-acting antiviral (DAA) era, it is important to understand the immunological changes after HCV eradication in HCV monoinfected (mHCV) and in HIV/HCV coinfected (HIV/HCV) patients. In this study, we analyzed sub-populations of monocytes, dendritic cells (DCs), T-lymphocytes and inflammatory biomarkers following initiation of DAA in 15 mHCV and 16 HIV/HCV patients on effective antiretroviral therapy at baseline and after sustained virological response at 12 weeks (SVR12). Fifteen age- and sex-matched healthy donors (HD) were enrolled as a control group. Activated CD4+ and CD8+ T-lymphocytes, mDCs, pDCs, MDC8 and classical, non-classical and intermediate monocytes were detected using flow cytometry. IP-10, sCD163 and sCD14 were assessed by ELISA while matrix metalloproteinase-2 (MMP-2) was measured by zymography. At baseline, increased levels of IP-10, sCD163 and MMP-2 were found in both HIV/HCV and mHCV patients compared to HD, whereas sCD14 increased only in HIV/HCV patients. After therapy, IP-10, sCD163 and sCD14 decreased, whereas MMP-2 persistently elevated. At baseline, activated CD8+ T-cells were high in HIV/HCV and mHCV patients compared to HD, with a decrease at SVR12 only in HIV/HCV patients. Activated CD4+ T-cells were higher in HIV/HCV patients without modification after DAAs therapy. These results suggest complex interactions between both viruses and the immune system, which are only partially reversed by DAA treatment.

A Novel Type I Interferon Primed Dendritic Cell Subpopulation in TREX1 Mutant Chilblain Lupus Patients.

Heterozygous TREX1 mutations are associated with monogenic familial chilblain lupus and represent a risk factor for developing systemic lupus erythematosus. These interferonopathies originate from chronic type I interferon stimulation due to sensing of inadequately accumulating nucleic acids. We here analysed the composition of dendritic cell (DC) subsets, central stimulators of immune responses, in patients with TREX1 deficiency. We performed single-cell RNA-sequencing of peripheral blood DCs and monocytes from two patients with familial chilblain lupus and heterozygous mutations in TREX1 and from controls. Type I interferon pathway genes were strongly upregulated in patients. Cell frequencies of the myeloid and plasmacytoid DC and of monocyte populations in patients and controls were similar, but we describe a novel DC subpopulation highly enriched in patients: a myeloid DC CD1C+ subpopulation characterized by the expression of LMNA, EMP1 and a type I interferon- stimulated gene profile. The presence of this defined subpopulation was confirmed in a second cohort of patients and controls by flow cytometry, also revealing that an increased percentage of patient’s cells in the subcluster express costimulatory molecules. We identified a novel type I interferon responsive myeloid DC subpopulation, that might be important for the perpetuation of TREX1-induced chilblain lupus and other type I interferonopathies.

Intranasal Delivery of RIG-I Agonist Drives Pulmonary Myeloid Cell Activation in Mice.

Viral respiratory infections cause substantial health and economic burden. There is a pressing demand for efficacious vaccination strategies and, therefore, a need for a better understanding of the mechanisms of action of novel potential adjuvants. Here we investigated the effect of a synthetic RIG-I agonist, the dsRNA hairpin 3p10LA9, on the activation of pulmonary myeloid cells. Analysis of early innate immune responses revealed that a single intranasal 3p10LA9 dose induces a transient pulmonary interferon-stimulated gene (ISG) and pro-inflammatory cytokine/chemokine response, which leads to the maturation of three distinct dendritic cell subpopulations in the lungs. While lung resident dendritic cell decrease shortly after 3p10LA9 delivery, their numbers increase in the draining mediastinal lymph node, where they have migrated, maintaining their activated phenotype. At the same time, dsRNA hairpin-induced chemokines attract transiently infiltrating monocytes into the lungs, which causes a short temporary pulmonary inflammation. However, these monocytes are dispensable in controlling influenza infection since in CCR2 deficient mice, lacking these infiltrating cells, the virus load was similar to the wild type mice when infected with the influenza virus at a sublethal dose. In summary, our data suggest that intranasal delivery of dsRNA hairpins, used as a RIG-I targeting adjuvant, represents an attractive strategy to boost type I inteferon-mediated lung dendritic cell maturation, which supports viral reduction in the lungs during infection.

Abstract 3582: Single-cell RNA-sequencing for immune profiling of SARS-CoV2 vaccine response in healthy individuals and patients with precursor plasma cell malignancies

Abstract Introduction: Patients with hematological malignancies exhibit inferior response to SARS-CoV2 vaccination, compared to healthy individuals, however little is known about patients with precursor hematological malignancies and the cellular underpinnings of vaccination response. Monoclonal Gammopathy of Undetermined Significance (MGUS) and Smoldering Myeloma (SMM) are plasma cell premalignancies that precede Multiple Myeloma (MM) and exhibit signs of immune dysregulation; they affect approximately 5% of the population over 50 years of age, who remain largely undiagnosed, due to lack of screening. In November 2019, we launched the IMPACT study to characterize the immune response to SARS-CoV2 vaccination in patients with plasma cell dyscrasias and healthy individuals. Methods: We performed single-cell RNA-sequencing on 224 peripheral blood mononuclear cell samples drawn from 118 IMPACT (IRB #20-332) participants with MGUS (n=20), SMM (n=48), or MM (n=24), as well as healthy individuals (n=26). Samples were collected before vaccination and after 2 doses of BNT162b2 (Pfizer-BioNtech) (n=123), mRNA-1273 (Moderna) (n=83) or 1 dose of Ad26.COV2.S (Janssen) (n=14). Results: Overall, we sequenced 2,025,611 cells from 224 samples of 118 patients with MGUS, SMM, MM and healthy individuals pre- and post-vaccination for SARS-CoV2, and profiled 553,082 T-cells, 95,392 B-cells, 74,394 NK cells, 195,371 Monocytes, and 35,236 Dendritic cells (DC). We identified activated clusters of B-cells, NK cells and DCs expressing genes such as CD83, CD69, CXCR4, and genes related to the NF-kB and AP-1 pathways. We compared cell type abundances pre- and post-vaccination within each participant population and found that activated CD83+ cells significantly increased post-vaccination in healthy individuals and patients with MGUS (paired t-test, q < 0.1), but not in patients with SMM or overt MM. At baseline, patients with SMM and MM had significantly fewer memory B-cells and significantly more cytotoxic T-cells and NK cells, compared to healthy individuals (Wilcoxon, q < 0.1), which could partly explain the differences observed post-vaccination. Patients with MM also had significantly higher levels of tolerogenic IL-10-expressing DCs (DC10) at baseline (Wilcoxon, q < 0.1), which could be dampening antigen-specific T-cell responses. Conclusion: We identified a significant expansion of activated B-cell, NK cell and DC subpopulations expressing CD83, CD69 and CXCR4, following vaccination in healthy individuals and patients with MGUS, but less so in patients with SMM and overt MM. Our results provide insight into the cellular mechanisms of immune response to SARS-CoV2 vaccination in healthy individuals and patients with precursor plasma cell malignancies and suggest that asymptomatic individuals with SMM may exhibit inferior response to vaccination. Citation Format: Romanos Sklavenitis-Pistofidis, Yoshinobu Konishi, Michelle Aranha, Mahshid Rahmat, Ting Wu, Michael Timonian, Shohreh Varmeh, Daniel Heilpern-Mallory, Michael P. Agius, Nang K. Su, Elizabeth D. Lightbody, Jacqueline Perry, Erica M. Horowitz, Anna V. Justis, Daniel Auclair, Catherine R. Marinac, Eric S. Fischer, Gad Getz, Irene M. Ghobrial. Single-cell RNA-sequencing for immune profiling of SARS-CoV2 vaccine response in healthy individuals and patients with precursor plasma cell malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3582.

Ischemic post-conditioning regulates early inflammation response via STAT3 pathway at reperfusion in a mouse model of myocardial infarction

The protection against reperfusion injury conferred by ischemic post-conditioning (IPoC) has been reported to rely on several signalization pathways like RISK and SAFE. However, their respective roles and the downstream-mechanisms involved are not fully understood S727 STAT3 has been proposed to be required for STAT3 translocation to mitochondria. However, in recent years, several groups, amongst which our group, have contested the reality of STAT3 translocation in mitochondria of cardiomyocytes. Revisiting STAT3-dependent mechanisms involved in IPoC thus looks required and could open up a new understand of how it can efficiently decrease infarct size in animal models. Decipher STAT3-dependent mechanisms by which IPOC protects myocardium against reperfusion injury. C57b mice were subjected to ischemia-reperfusion with or without IPoC in presence/absence of STAT3 inhibitor ( n = 8 per each group). Heart, PBMC and blood samples were analyzed to determined: infarct size, phosphorylation level of STAT3 (Y705 and S727), genes and proteins expression, cytokines and troponin levels, immune cell type populations. I/R induced STAT3 phosphorylation at residues Y705 and S727, while IPoC mostly enhanced phosphorylation Y705-STAT3 residue within 15 minutes of reperfusion in the area-at-risk. No significant change in S727-STAT3 phosphorylation was detected. Inhibition of Y705-STAT3 phosphorylation increased by Stattic treatment prevented the cardioprotective effect of IPoC on the infarct size. Gene analysis in the area-at-risk revealed clusters of genes involved in wound healing and inflammation at 3 h after reperfusion. Screening of immune cells in myocardium 24 h after reperfusion revealed a decrease in neutrophils and macrophages, in the line of the decrease in infarct size. However, we noteworthily identified that IPoC was associated with an increase in a subpopulation of macrophages or dendritic cells that is not detected after Stattic treatment 24 h after reperfusion. Phosphorylation of Y705 STAT3 is critical for the protection induced by IPoC against reperfusion injury and it could, non-exhaustively, rely on the modulation of the inflammatory response during the first hours of reperfusion.

Preparation and identification of monoclonal antibodies against porcine CD103.

Dendritic cells (DCs) play an important role in activating, regulating, and maintaining the immune response. CD103+ DCs, one of the DC subpopulations, mainly function in the mucosal immune response. They are responsible for capturing and carrying antigens to the relevant lymph nodes to activate the downstream immune responses. However, there is limited available information regarding the function of CD103+ DCs in the porcine mucosal immune response. In this study, two monoclonal antibodies (mAbs) against porcine CD103 were prepared, and their applications were evaluated by enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescence assay (IFA), and flow cytometry. The produced mAbs (7F3 and 9H3) were both IgG1 subtype with κ chains in the light chain. The 7F3 recognizes a linear epitope (PDLRPRAQVYFSDLE) while 9H3 recognizes another linear epitope (QILDEGQVLLGAVGA). The prepared mAbs could be used in vivo to detect the cells expressing CD103 molecules, giving wide applications of both mAbs. In conclusion, this study successfully prepared 2 mAbs against CD103 protein, and they showed applicability in vivo experiments, which will provide the basis for the study of porcine mucosal immunity. KEY POINTS: •Preparation of monoclonal antibodies against porcine CD103 molecule •Analysis of the distribution of CD103 protein on different cells is possible •Exploration of the CD103+ DCs function in porcine mucosal immunity is possible.

Characterization of cellular subpopulations and their gene expression by single-cell RNA sequencing in canine atopic dermatitis

Abstract Atopic Dermatitis (AD) is the most common, chronic, and inflammatory allergic skin disease worldwide, with a high prevalence both in children and adults, particularly in developed countries. There are limited effective treatments for severe allergic skin diseases available, thus, there is an unmet need of better understanding the molecular mechanisms and cellular populations involved in AD. Since AD in canines closely resembles the disease in humans, they are an attractive animal model for further studies. Leveraging single-cell RNA sequencing, we identified the cellular composition and shifts in cell populations in canine epidermis of atopic dogs compared to the epidermis from healthy controls. Fibroblasts and keratinocytes represented the largest cell populations, with fibroblasts decreasing in the atopic epidermis. Other populations such as endothelial vascular cells showed differences as well. Shifts in immune cell distribution included changes in subpopulations of dendritic cells and monocytes in the atopic skin. NK and T cells, particularly CD8 T cells were increased. Subclustering revealed specific cellular changes in AD dogs. We found signifiant changes in gene expression in most cell populations, with some genes differentially expressed across cells, while others were expressed in a cell specific manner. We also observed subtle differences between samples from animals with different disease progression, identifying gene expression markers changing with AD severity. Here we show that single-cell sequencing is a useful tool to define the cellular composition in canine atopic dermatitis, resolving changes in gene expression at the cellular level to advance our understanding of disease development and progression. Supported by intramural funds from Western University of Health Sciences

An Experimental Model of Neuro-Immune Interactions in the Eye: Corneal Sensory Nerves and Resident Dendritic Cells.

The cornea is an avascular connective tissue that is crucial, not only as the primary barrier of the eye but also as a proper transparent refractive structure. Corneal transparency is necessary for vision and is the result of several factors, including its highly organized structure, the physiology of its few cellular components, the lack of myelinated nerves (although it is extremely innervated), the tightly controlled hydration state, and the absence of blood and lymphatic vessels in healthy conditions, among others. The avascular, immune-privileged tissue of the cornea is an ideal model to study the interactions between its well-characterized and dense sensory nerves (easily accessible for both focal electrophysiological recording and morphological studies) and the low number of resident immune cell types, distinguished from those cells migrating from blood vessels. This paper presents an overview of the corneal structure and innervation, the resident dendritic cell (DC) subpopulations present in the cornea, their distribution in relation to corneal nerves, and their role in ocular inflammatory diseases. A mouse model in which sensory axons are constitutively labeled with tdTomato and DCs with green fluorescent protein (GFP) allows further analysis of the neuro-immune crosstalk under inflammatory and steady-state conditions of the eye.

A subpopulation of green turtle suprabasal epidermal cells are Langerin+ and migrate under in vitro stimulation of the chemokine CCL21.

Dendritic cells form the link between the innate and adaptative immune response, particularly on mucosal and epidermal surfaces. The Langerhans, an epidermal dendritic cell subpopulation, play a key role in the skin immune response across several species. Scarse immune cell subpopulations, including Langerhans-like cells, have been identified in endangered green turtles thereby complicating the understanding of the pathogenesis of diseases such as fibropapillomatosis, which induces skin tumours in this species worldwide. In biopsies from green turtle skin, we demonstrated that the polyclonal anti-human Langerin antibodies strongly stained a Langerin+ cell population in epidermal sheets, the suprabasal layer of the epidermis in cryosections and in cells from cytospin preparation of migration assays. The morphology of these cells was round to amoeboid in normal skin; however, in skin with ulcerative dermatitis, Langerin+ cells aggregated around ulcers and adopted a more pleomorphic morphology. To our knowledge, this is the first identification of Langerin+ cells with a molecular marker in a reptile species.

Dendritic cells may help differentiate discoid lupus erythematosus alopecia from lichen planopilaris.

IntroductionPrimary cicatricial alopecia (PCA) encompasses a heterogeneous group of inflammatory diseases characterized by the replacement of hair follicle structures by fibrous tissue. Discoid lupus erythematosus (DLE) and lichen planopilaris (LPP) are the most common causes of scarring alopecia. The distinction between both entities is often challenging because of significant clinical and histopathological overlap.AimWe hypothesized that dendritic cells which are implicated in PCA pathogenesis can provide a reliable histopathological clue to distinguish between these two entities.Material and methodsIn a retrospective cohort study including 51 patients diagnosed with LPP and DLE we mapped and quantified the distribution of dendritic cells. Cell count in lesional skin was performed on immunohistochemistry by using characteristic monoclonal antibodies to specific subpopulations of dendritic cells.ResultsWe demonstrated that almost all subpopulations of dendritic cells were highly expressed in lesional skin of discoid lupus erythematosus patients in comparison with lichen planopilaris ones.ConclusionsIn the light of this observation, dendritic cells might be used as an additional clue in differential diagnosis of PCA.

Isolating and Targeting a Highly Active, Stochastic Dendritic Cell Subpopulation for Improved Immune Responses

Isolating and Targeting a Highly Active, Stochastic Dendritic Cell Subpopulation for Improved Immune Responses

Novel approaches to increase resistance to acute respiratory infections

Relevance . Respiratory infections are the most common in the world. In order to prevent epidemics, there is a need to improve the strategies for organizing medical care and develop new approaches in order to increase the nonspecific resistance, mobilize innate immunity. Objective . The aim of this study was to investigate the effect of glucosaminylmuramyldipeptide (GMDP) on the level of expression of markers of differentiation and activation of functionally significant subpopulations of dendritic cells in peripheral blood mononuclear cells of healthy donors,the second aim was to assess the effectiveness of GMDP in the prevention of acute respiratory infections in an unfavorable epidemiological period of the COVID-19 pandemic. Materials and Methods . An open comparative study included 309 apparently healthy participants, aged 19-22 years. At the first stage of the study, 42 participants (22 female and 20 male) took the drug Licopid 1 mg for 10 days according to the instructions, 1 tablet 3 times a day in order to prevent acute respiratory infections. Peripheral blood sampling was performed before taking the drug (day 0) and the next day after the last dose of the drug (day 12). Evaluation of the expression of markers of differentiation and activation of dendritic cell subpopulations HLA-DR, CD11c, CD123, CD80, CD83, CCR7, CD3, CD14, CD20 was assessed by flow cytometry. At the same time, mRNA was isolated from mononuclear cells of perfusion blood and, after reverse transcription, the level of gene expression was determined by RT PCR. At the next stage, the effectiveness of the prophylactic use of the drug Licopid in 267 students of the Institute of Physical Culture was assessed in order to prevent acute respiratory infections in an unfavorable epidemiological period; the observation period was 12 months. Results and Discussion . A study of the relative quantitative composition of DCs in the peripheral blood of healthy donors by flow cytometry revealed the possibility of an increase in their total number, as well as subpopulations of MDC and PDC under the influence of GMDP. There was a statistically significant increase in the receptors for the chemokine CCR7, which is responsible for the recruitment of DCs to the secondary lymphoid organs. Analysis of the levels of expression of genes XCR1, CD11b , and CD103 showed a statistically significant effect of GMDP on an increase in their expression compared to the baseline level (before GMDP intake), with the mean value being higher in participants undergoing moderate exercise. It was found that the use of the drug Licopid 1mg for the purpose of preventing and reducing the seasonal incidence of acute respiratory infections at the stage of basic training of students of the Institute of Physical Culture contributed to a decrease in the incidence of acute respiratory infections within 12 months of observation after taking the drug. The number of episodes of acute respiratory infections decreased 3.7 times, while the group with 3 or more episodes of acute respiratory infections during the year, which constituted 14.5 % of participants, completely disappeared. The maximum efficiency of GMDP was observed in the track and field command, in which the number of participants who had no episodes of acute respiratory infections during the year increased by 7 times. Conclusion . Our data complement the modern understanding of the molecular mechanism of action of GMDP and substantiate the possibility of its experimental and clinical use in order to develop new strategies for organizing medical care in order to increase the nonspecific resistance of the organism.