Frequency Of Dendritic Cells Research Articles

The blood mMDSC to DC ratio is a sensitive and easy to assess independent predictive factor for epithelial ovarian cancer survival

ABSTRACTEpithelial ovarian cancer (EOC) may cause abnormal blood levels of leukocytes. This paraneoplastic manifestation is associated with a worse response to therapy and shorter survival. To understand the complexity and nature of these leukocytes, we dissected the different populations of myeloid cells and analyzed their relation to clinical outcome. Therefore, baseline blood samples of 36 EOC patients treated either with carboplatin/doxorubucin or with gemcitabine were analyzed for different subsets of monocytes/macrophages, myeloid derived suppressor cells (MDSC) and dendritic cells (DC) using multiparameter flow cytometry as well as functional assays for myeloid cell mediated suppression of antigen-specific T cell reactivity. Healthy donor blood served as control. EOC patients displayed an increase in monocytes/macrophages, monocytic MDSC (mMDSC) and CD33-CD11b+CD14-CD15- double-negative MDSC (CD33- dnMDSC) and a decrease in the frequency of DC, across all EOC subtypes. A low frequency of DC and high frequencies of monocytes/macrophages and mMDSC, but not CD33- dnMDSC, were associated with poor overall survival. Patient's monocytes/macrophages and mMDSC, but not CD33- dnMDSC, were shown to suppress T cell reactivity in vitro. The mMDSC and DC frequencies were not altered upon treatment. Importantly, the mMDSC to DC ratio was the strongest independent, highly sensitive and specific, predictive factor for survival. This was irrespective of the type of chemotherapy or disease stage and outperformed classical parameters as WHO status or time from last chemotherapy. Thus, the baseline blood mMDSC to DC ratio is a robust, independent and easy to analyze predictive factor for EOC survival, and may assist patient selection for immunotherapy.

Ibrutinib has a novel immunomodulatory effect by enhancing DC maturation both in vivo and in a model of inflammation

Abstract Myeloid derived suppressor cells (MDSCs) can inhibit T cell activation by altering the characteristics and activation of dendritic cells (DCs). We had previously reported that Ibrutinib enhances the expression of co-stimulatory molecules on DCs and promotes DC-mediated T cell activation. In the present study we further determined the mechanisms of DC immunomodulation by Ibrutinib. We evaluated the effect of Ibrutinib on (i) DC maturation and migration from the injection site to draining lymph nodes, (ii) T cell proliferation in vivo, and (iii) monocyte maturation to DCs using a mouse inflammation model. DCs were generated from mouse bone marrow-derived cells in the presence of vehicle or 10μM lbrutinib. CFES-labelled DCs were injected subcutaneously into the footpads of naive mice, and their migration to the regional lymph nodes and maturation profile was analyzed by flow cytometry. To evaluate T cell priming, CFSE-labelled OVA-specific T cells isolated from OT-II mice were injected into the tail vein of syngeneic mice that were prior injected with mature DCs loaded with OVA peptide. After four days, T cell proliferation was evaluated by CFSE dilution. In the inflammation model, C57BL6 mice were treated with vehicle or 6mg/kg/day Ibrutinib orally for a week. A sub-lethal dose of LPS was injected in the dorsal skin and the frequency of inflammatory monocytes and mature DCs was determined. We found that Ibrutinib significantly improves DC maturation and migration, inducing T cell activation and proliferation in vivo. In addition, Ibrutinib enhances monocyte maturation to DCs in the skin. The results suggest a novel effect of Ibrutinib, which may have therapeutic use for cancers characterized by a high MDSC infiltration.

Alterations in natural killer and dendritic cell subsets in individuals with HIV‐associated neurotuberculosis

One of the commonest HIV-associated opportunistic infections of the central nervous system is neurotuberculosis. Interaction between HIV, Mycobacterium tuberculosis and host immune system in co-infected individuals may result in altered frequencies of immune cells, thereby modulating dissemination and disease progression. We examined the frequencies of natural killer (NK) cell and dendritic cell (DC) subsets in HIV infected individuals with neurotuberculosis (HIVNTB) as compared to individuals with HIV associated systemic TB (HIVSTB), asymptomatic HIV, non-HIV NTB, non-HIV STB, and healthy controls. Peripheral blood mononuclear cells (PBMC) were stained with fluorochrome-conjugated monoclonal antibodies- Lineage cocktail (containing CD3, CD14, CD19, and CD20), HLA-DR, CD16, CD56, CD11c, and CD123, fixed with 2% paraformaldehyde and analyzed on the flow cytometer. The pDCs were significantly reduced in all HIV infected groups, with a marked reduction in HIVNTB cases as compared to healthy controls. While the CD56- CD16bt NK cell subset displayed a significant increase in frequency in all three HIV infected groups compared the three HIV negative groups, the CD56dim CD16bt subset was significantly lower in frequency in the HIVNTB compared to healthy controls. The decreased frequencies of plasmacytoid DCs and cytotoxic NK cells, which are crucial for innate immune defence against HIV, may result in ineffective virus control and lead to an exacerbated course of disease in HIVNTB individuals.

OP030 Loss of PTPN2 in dendritic cells promotes T-cell activation and expression of co-stimulatory molecules

Variants within the gene locus encoding protein tyrosine phosphatase non-receptor type 2 (PTPN2) are associated with the development of inflammatory disorders. The role of PTPN2 in T cells and intestinal epithelial cells has been investigated in depth, but its role in dendritic cells (DCs) remains unclear. Here, we addressed whether loss of PTPN2 in DCs affects the expression of the co-stimulatory molecules and subsequently activation of T cells. For this aim, we generated mice lacking PTPN2 specifically in DCs (PTPN2-CD11cCre mice). Using flow cytometry, we analysed spleen, mesenteric lymph nodes, and lamina propria in PTPN2-CD11cCre and their wild-type littermate controls. PTPN2-CD11cCre mice show symptoms of splenomegaly and dermatitis, as well as inflammatory infiltrations in the liver and lung in some mice. Severity of the inflammation varies between individuals, resulting in spontaneous death in some mice. PTPN2-CD11cCre mice do not differ in terms of DCs frequencies in spleen and mesenteric lymph nodes compared with their wild-type littermate controls, but we observed an increased expression of co-stimulatory molecules CD80 and CD86. In the lamina propria, however, DC frequencies were reduced, and the remaining DCs expressed reduced levels of CD80 and CD86. Of note, there was no difference regarding the expression of MHCII on CD11c+ cells between PTPN2-CD11cCre and their littermate controls. Consistent with increased expression of co-stimulatory molecules, we observed increased numbers of CD44+ effector/memory CD4+ and CD8+ T cells, as well as IFN-gamma+CD4+ T cells, indicating an enhanced T-cell activation capacity of PTPN2-deficient DCs. In conclusion, our results show that PTPN2 has an important anti-inflammatory role in DCs. Loss of PTPN2 in DCs promotes T-cell activation as well as increased expression of CD80 and CD86. Furthermore, it increases the ratio between CD11b+ DC2 and CD24+DC1 in skin and lymph nodes.

Abstract B26: Sarcoma microenvironment blocks DC but promotes macrophage differentiation from tumor-infiltrating monocytes

Abstract Sarcomas are rare and heterogeneous cancer of mesenchymal origin. Treatment options have largely remained unchanged over decades and metastatic sarcoma is essentially incurable. There are more than 60 distinct diagnostic subtypes of sarcoma, many of which do not harbor consistent mutations. These factors make the development of targeted therapy particularly challenging in sarcomas. Therefore, a new therapeutic approach broadly targeting sarcomas of various subtypes is highly desirable. Immunotherapy offers a viable approach in cancer treatment, which has not been adequately explored in sarcomas. The immune system can distinguish malignant from normal cells and mount an antitumor T-cell response. However, tumors create a highly immunosuppressive microenvironment, which counteracts both endogenous as well as therapy-induced antitumor immune responses. Therefore, understanding the cellular and molecular basis of immunosuppression in sarcoma microenvironment is important for the development and success of any immunotherapeutic approach. Macrophages (MACs) and dendritic cells (DC) are antigen-presenting cells (APC) of the innate immune system that play key role in shaping immune responses. Studies in carcinomas have shown that immunosuppressive MACs greatly outnumber immunostimulatory DCs in the tumor microenvironment. Currently, it is unclear whether sarcomas also harbor such polarized distribution of APC in their microenvironment. Tumor-associated MACs can develop from circulating monocytes or from preexisting tissue macrophages. Likewise, DCs can develop from circulating monocytes or bone marrow-derived precursors. However, the origin of sarcoma-infiltrating MACs and DCs is unclear. Insights into the distribution and origin of tumor-infiltrating APCs is critical for devising therapeutic approaches targeting these cells to counteract immunosuppression in tumor microenvironment. We have addressed this issue by using several distinct murine models of sarcomas. Based on genetic background sarcomas can be divided into (1) translocation-associated sarcomas, (2) sarcomas harboring mutations in oncogenes and tumor suppressors, and (3) sarcomas with complex karyotypes displaying significant genomic instability. We selected one murine model to represent each of the three subtypes. An SYT-SSX fusion oncogene-driven mouse model of synovial sarcoma represented group 1, loss of P53 coupled with activation of oncogenic KRAS-driven mouse model of undifferentiated pleomorphic sarcoma represented group 2, and syngeneic transplant of sarcoma cell lines derived from methylcholanthrene-induced fibrosarcomas represented group 3. In all three murine models, APCs were found to comprise the majority of leukocyte infiltrates in tumors. Using multiparametric flow cytometry, gene-expression profiling, and lineage labeling we found that the vast majority of APCs in sarcoma were MACs with DCs comprising a very small subset. Next, using a combination of in vivo lineage tracing and lineage ablation we uncovered that the majority of MACs and DCs were derived from circulating monocytes. These results suggest that monocytes preferentially differentiate into macrophages but not DCs in sarcoma microenvironment. These findings lay the groundwork for future efforts in our laboratory aimed at understanding the molecular basis for such polarized macrophage differentiation in the tumor microenvironment. The overarching goal is to translate our findings into therapeutic approaches aimed at increasing the frequency of immunostimulatory DCs while reducing immunosuppressive MACs in sarcoma microenvironment. The clinical benefits of such an approach will be two-fold: (1) reduced immunosuppression in the tumor microenvironment increasing the efficacy of therapeutically generated T cells, and (2) increased probability of generating endogenous antitumor immune responses via the activity of DCs in the tumor microenvironment. Citation Format: Samir Devalaraja, Ian Folkert, Minghong Li, Yuma Tada, Kanika Jain, Malay Haldar. Sarcoma microenvironment blocks DC but promotes macrophage differentiation from tumor-infiltrating monocytes [abstract]. In: Proceedings of the AACR Conference on Advances in Sarcomas: From Basic Science to Clinical Translation; May 16-19, 2017; Philadelphia, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(2_Suppl):Abstract nr B26.

Mesenchymal stromal cells modulate gut inflammation in experimental colitis.

Inflammatory bowel diseases (IBDs)affect millions of people worldwide and their frequencies in developed countries have increased since the twentieth century. In this context, there is an intensive search for therapies that modulate inflammation and provide tissue regeneration in IBDs. Recently, the immunomodulatory activity of adipose tissue-derived mesenchymal stromal cells (ADMSCs) has been demonstrated to play an important role on several immune cells in different conditions of inflammatory and autoimmune diseases. In this study, we explored the immunomodulatory potential of ADMSC in a classical model of DSS-induced colitis. First, we found that treatment of mice with ADMSC ameliorated the severity of DSS-induced colitis, reducing colitis pathological score and preventing colon shortening. Moreover, a prominent reduction of pro-inflammatory cytokines levels (i.e., IFN-γ, TNF-α, IL-6 and MCP-1) was observed in the colon of animals treated with ADMSC. We also observed a significant reduction in the frequencies of macrophages (F4/80+CD11b+) and dendritic cells (CD11c+CD103+) in the intestinal lamina propria of ADMSC-treated mice. Finally, we detected the up-regulation of immunoregulatory-associated molecules in intestine of mice treated with ADMSCs (i.e., elevated arginase-1 and IL-10). Thus, this present study demonstrated that ADMSC modulates the overall gut inflammation (cell activation and recruitment) in experimental colitis, providing support to the further development of new strategies in the treatment of intestinal diseases.

Neonatal immune response to rhinovirus A16 has diminished dendritic cell function and increased B cell activation.

BackgroundRhinovirus infections during infancy account for the majority of respiratory illness health care utilization and are an associated risk factor for subsequent development of allergic asthma. Neonatal type I interferon production is diminished compared to adults after stimulation with TLR agonists. However, broad profiling of immune cell responses to infectious rhinovirus has not been undertaken and we hypothesized that additional immune differences can be identified in neonates. In this study, we undertook a comparative analysis of neonatal and adult blood immune cell responses after in vitro incubation with infectious RV-A16 for 6 and 24 hours.MethodsIntracellular proinflammatory and type I interferon cytokines along with expression of surface co-stimulatory and maturation markers were measured using multi-parameter flow cytometry.ResultsBoth circulating myeloid dendritic cell (mDC) and plasmacytoid dendritic cell (pDC) frequency were lower in cord blood. Qualitative and quantitative plasmacytoid dendritic cell IFN-alpha + TNF- alpha responses to rhinovirus were significantly lower in cord pDCs. In cord blood samples, the majority of responsive pDCs were single-positive TNF-alpha producing cells, whereas in adult samples rhinovirus increased double-positive TNF-alpha+IFN-alpha+ pDCs. Rhinovirus upregulated activation and maturation markers on monocytes, mDCs, pDCs, and B cells, but CD40+CD86+ monocytes, mDCs, and pDCs cells were significantly higher in adult samples compared to cord samples. Surprisingly, rhinovirus increased CD40+CD86+ B cells to a significantly greater extent in cord samples compared to adults.ConclusionsThese findings define a number of cell-specific differences in neonatal responses to rhinovirus. This differential age-related immune response to RV may have implications for the immune correlates of protection to viral respiratory illness burden and determination of potential biomarkers for asthma risk.

Corneal Tissue From Dry Eye Donors Leads to Enhanced Graft Rejection.

To assess the effect of dry eye disease (DED) in graft donors on dendritic cell (DC) maturation, host T-cell sensitization, and corneal allograft rejection. Corneas of control (healthy donor) and DED mice (C57BL/6) were transplanted onto fully allogeneic naive BALB/c recipients (n = 10 mice/group). Long-term allograft survival was evaluated for 8 weeks. Corneas and draining lymph nodes (dLNs) were harvested at posttransplantation day 14 (n = 5 mice/group). The frequencies of MHCII CD11c DCs in the donor corneas and host dLNs and the frequencies of interferon (IFN)-γ and IL-17 CD4 T cells and Foxp3 expression by Tregs in host dLNs were investigated using flow cytometry. The enzyme-linked immunospot assay was used to assess host T-cell allosensitization through direct and indirect pathways (n = 3/group). Recipients of DED donor corneas showed significantly reduced graft survival (10%) compared with control mice (50% survival, P = 0.022), and had significantly increased frequencies of mature DCs in the grafted cornea (DED donor 44.0% ± 0.36% vs. healthy donor 35.4 ± 0.5%; P < 0.0001) and host dLNs (DED donor 25.1% ± 0.66% vs. healthy donor 13.7% ± 1.6%; P = 0.005). Frequencies of IFN-γ and IL-17 T cells were increased in the dLNs of recipients of DED corneas, whereas the expression (mean fluorescence intensity) of Foxp3 in Tregs was decreased significantly in these mice (DED donor 6004 ± 193 vs. healthy donor 6806 ± 81; P = 0.0002). Enzyme-linked immunospot analysis showed that the direct pathway of allosensitization was significantly amplified in recipients of grafts with DED (P = 0.0146). Our results indicate that DED in the donor is a significant risk factor for subsequent corneal allograft rejection.

Constitutive CD40 Signaling in Dendritic Cells Limits Atherosclerosis by Provoking Inflammatory Bowel Disease and Ensuing Cholesterol Malabsorption

The costimulatory molecule CD40 is a major driver of atherosclerosis. It is expressed on a wide variety of cell types, including mature dendritic cells (DCs), and is required for optimal T-cell activation and expansion. It remains undetermined whether and how CD40 on DCs impacts the pathogenesis of atherosclerosis. Here, the effects of constitutively active CD40 in DCs on atherosclerosis were examined using low-density lipoprotein-deficient (Ldlr-/-) bone marrow chimeras that express a transgene containing an engineered latent membrane protein 1 (LMP)/CD40 fusion protein conferring constitutive CD40 signaling under control of the DC-specific CD11c promoter (DC-LMP1/CD40). As expected, DC-LMP1/CD40/Ldlr-/- chimeras (DC-LMP1/CD40) showed increased antigen-presenting capacity of DCs and increased T-cell numbers. However, the mice developed extensive neutrophilia compared to CD40wt/Ldlr-/- (CD40wt) chimeras. Despite overt T-cell expansion and neutrophilia, a reduction in conventional DC frequency and a dramatic (approximately 80%) reduction in atherosclerosis was observed. Further analyses revealed that cholesterol and triglyceride levels had decreased by 37% and 60%, respectively, in DC-LMP1/CD40 chimeras. Moreover, DC-LMP1/CD40 chimeras developed inflammatory bowel disease characterized by massive transmural influx of leukocytes and lymphocytes, resulting in villous degeneration and lipid malabsorption. Constitutive activation of CD40 in DCs results in inflammation of the gastrointestinal tract, thereby impairing lipid uptake, which consequently results in attenuated atherosclerosis.

A Review on Defects of Dendritic Cells in Common Variable Immunodeficiency.

Common variable immunodeficiency (CVID) is the most important primary disorder that is associated with clinical complications including recurrent infections, malignancy and autoimmune diseases. The genetic cause of CVID is mostly unknown and only a few genetic causes are identified. The various options are proposed for determining the etiology of CVID patients, such as T- and B-cell defects, Toll-like receptors (TLRs) impairments, altered cytokine production as well as blemished dendritic cells (DCs). The patients with CVID show a reduction in number and frequency of DCs in blood, an altered expression of cell surface molecules, and defective activation through toll-like receptors (TLRs). Also loss of IFNα has a critical role in B-cell impairments of CVID patients. The aim of this review is to collect under one umbrella, all the recent knowledge about DCs defects of CVID patients. This review covers basic information about physiology of DCs followed by reports of DCs situation in CVID. According to the results of researches assessing DCs frequency and function in CVID, the roll of DCs in the pathogenesis of CVID cannot be ruled out. The article is expected to encourage the researchers to do comprehensive researches about complex connections between DCs and other immune cells in CVID.

Safety and in vivo immune assessment of escalating doses of oral laquinimod in patients with RRMS

BackgroundLaquinimod is an oral immunomodulator in clinical development to treat relapsing-remitting multiple sclerosis (RRMS). Laquinimod is in clinical development for the treatment of multiple sclerosis and Huntington Disease (HD). The objective of this study is to assess the safety, tolerability, pharmacokinetics (PK) and cytoimmunologic effects following escalating doses of laquinimod in patients with RRMS.MethodsOne hundred twelve patients were randomly assigned to laquinimod/placebo in a series of separate dose-escalating cohorts starting from a daily oral dose of 0.9 mg/1.2 mg escalating to 2.7 mg, in 0.3 mg increments.ResultsTwenty-eight patients received placebo and 84 received laquinimod ranging from 0.9 to 2.7 mg. No deaths occurred. One serious adverse event (SAE) of perichondritis was reported, which was unrelated to laquinimod (0.9 mg). There was no increased incidence of adverse events (AEs) with escalating doses. Laquinimod-treated patients showed more abnormal laboratory levels in liver enzymes, P-amylase, C-reactive protein (CRP), and fibrinogen, but most shifts were clinically non-significant. The exposure of laquinimod was dose proportional and linear in the tested dose range. An immunological substudy showed significant dose-dependent decreases in 6-sulpho LacNAc + dendritic cell (slanDC) frequency following laquinimod compared to placebo.ConclusionLaquinimod doses up to 2.7 mg were safely administered to patients with RRMS. An in vivo effect of laquinimod on the innate immune system was demonstrated.Trial registrationEudraCT Number: 2009-011234-99. Registered 23 June 2009.

Redefining thymus medulla specialization for central tolerance.

During αβT cell development, the thymus medulla represents an essential microenvironment for T cell tolerance. This functional specialization is attributed to its typical organized topology consisting of a branching structure that contains medullary thymic epithelial cell (mTEC) networks to support negative selection and Foxp3+ T-regulatory cell (T-reg) development. Here, by performing TEC-specific deletion of the thymus medulla regulator lymphotoxin β receptor (LTβR), we show that thymic tolerance mechanisms operate independently of LTβR-mediated mTEC development and organization. Consistent with this, mTECs continue to express Fezf2 and Aire, regulators of intrathymic self-antigens, and support T-reg development despite loss of LTβR-mediated medulla organogenesis. Moreover, we demonstrate that LTβR controls thymic tolerance by regulating the frequency and makeup of intrathymic dendritic cells (DCs) required for effective thymocyte negative selection. In all, our study demonstrates that thymus medulla specialization for thymic tolerance segregates from medulla organogenesis and instead involves LTβR-mediated regulation of the thymic DC pool.

Pre-transplant infusion of donor-derived dendritic cells maintained at the immature stage by sinomenine increases splenic Foxp3+ Tregs in recipient rats after renal allotransplantation

ObjectiveThe immunosuppressive mechanism of sinomenine in organ allotransplantation was investigated, especially its effect of blocking dendritic cell (DC) maturation, which might influence the frequency of regulatory T cells (Tregs). MethodsBone marrow cells from male donor Wistar rats were induced to differentiate into DCs in vitro in the presence or absence of sinomenine, and characterized by flow cytometry. These two groups of DCs were respectively injected into male recipient Sprague-Dawley rats via the tail vein, at both high and low doses. Sprague-Dawley rats receiving saline injection were used as controls. Seven days later, renal transplantation was performed from donor Wistar rats to the recipient Sprague-Dawley rats. Seven days after transplantation, spleens were collected from the recipients. The proportions of Tregs and Foxp3+ Tregs to CD4+ T cells were determined using flow cytometry. ResultsWith sinomenine treatment, the frequency of mature DCs was reduced, as indicated by lower expression of the surface markers CD80, CD86, and RT1B. In recipient Sprague-Dawley rats that received sinomenine-treated DCs before renal allotransplantation, the proportions of splenic Tregs and Foxp3+ Tregs were significantly higher than in control recipients receiving saline or DCs without sinomenine treatment (all p<0.05). A high dose of sinomenine-treated DCs (106 cells) had a more obvious effect in increasing Tregs than the low dose (105 cells) (p<0.05). ConclusionPre-transplant infusion of donor-derived sinomenine-induced maturation arrested DCs could result in the increase of Foxp3+ Tregs in the spleens of recipients after renal allotransplantation.

An antigen-specific semi-therapeutic treatment with local delivery of tolerogenic factors through a dual-sized microparticle system blocks experimental autoimmune encephalomyelitis.

Antigen-specific treatments are highly desirable for autoimmune diseases in contrast to treatments which induce systemic immunosuppression. A novel antigen-specific therapy has been developed which, when administered semi-therapeutically, is highly efficacious in the treatment of the mouse model for multiple sclerosis, experimental autoimmune encephalomyelitis (EAE). The treatment uses dual-sized, polymeric microparticles (dMPs) loaded with specific antigen and tolerizing factors for intra- and extra-cellular delivery, designed to recruit and modulate dendritic cells toward a tolerogenic phenotype without systemic release. This approach demonstrated robust efficacy and provided complete protection against disease. Therapeutic efficacy required encapsulation of the factors in controlled-release microparticles and was antigen-specific. Disease blocking was associated with a reduction of infiltrating CD4+ T cells, inflammatory cytokine-producing pathogenic CD4+ T cells, and activated macrophages and microglia in the central nervous system. Furthermore, CD4+ T cells isolated from dMP-treated mice were anergic in response to disease-specific, antigen-loaded splenocytes. Additionally, the frequency of CD86hiMHCIIhi dendritic cells in draining lymph nodes of EAE mice treated with Ag-specific dMPs was reduced. Our findings highlight the efficacy of microparticle-based drug delivery platform to mediate antigen-specific tolerance, and suggest that such a multi-factor combinatorial approach can act to block autoimmunity.

Dendritic cells activation is associated with sustained virological response to telaprevir treatment of HCV-infected patients

First anti-HCV treatments, that include protease inhibitors in conjunction with IFN-α and Ribavirin, increase the sustained virological response (SVR) up to 80% in patients infected with HCV genotype 1. The effects of triple therapies on dendritic cell (DC) compartment have not been investigated. In this study we evaluated the effect of telaprevir-based triple therapy on DC phenotype and function, and their possible association with treatment outcome.HCV+ patients eligible for telaprevir-based therapy were enrolled, and circulating DC frequency, phenotype, and function were evaluated by flow-cytometry. The antiviral activity of plasmacytoid DC was also tested.In SVR patients, myeloid DC frequency transiently decreased, and returned to baseline level when telaprevir was stopped. Moreover, an up-regulation of CD80 and CD86 on mDC was observed in SVR patients as well as an improvement of IFN-α production by plasmacytoid DC, able to inhibit in vitro HCV replication.

RelB+ Steady-State Migratory Dendritic Cells Control the Peripheral Pool of the Natural Foxp3+ Regulatory T Cells.

Thymus-derived natural Foxp3+ CD4+ regulatory T cells (nTregs) play a key role in maintaining immune tolerance and preventing autoimmune disease. Several studies indicate that dendritic cells (DCs) are critically involved in the maintenance and proliferation of nTregs. However, the mechanisms how DCs manage to keep the peripheral pool at constant levels remain poorly understood. Here, we describe that the NF-κB/Rel family transcription factor RelB controls the frequencies of steady-state migratory DCs (ssmDCs) in peripheral lymph nodes and their numbers control peripheral nTreg homeostasis. DC-specific RelB depletion was investigated in CD11c-Cre × RelBfl/fl mice (RelBDCko), which showed normal frequencies of resident DCs in lymph nodes and spleen while the subsets of CD103− Langerin− dermal DCs (dDCs) and Langerhans cells but not CD103+ Langerin+ dDC of the ssmDCs in skin-draining lymph nodes were increased. Enhanced frequencies and proliferation rates were also observed for nTregs and a small population of CD4+ CD44high CD25low memory-like T cells (Tml). Interestingly, only the Tml but not DCs showed an increase in IL-2-producing capacity in lymph nodes of RelBDCko mice. Blocking of IL-2 in vivo reduced the frequency of nTregs but increased the Tml frequencies, followed by a recovery of nTregs. Taken together, by employing RelBDCko mice with increased frequencies of ssmDCs our data indicate a critical role for specific ssmDC subsets for the peripheral nTreg and IL-2+ Tml frequencies during homeostasis.

Evolving Identification of Blood Cells Associated with Clinically Isolated Syndrome: Importance of Time since Clinical Presentation and Diagnostic MRI.

It is not clear how the profile of immune cells in peripheral blood differs between patients with clinically isolated syndrome (CIS) and healthy controls (HC). This study aimed to identify a CIS peripheral blood signature that may provide clues for potential immunomodulatory approaches early in disease. Peripheral blood mononuclear cells (PBMCs) were collected from 18 people with CIS, 19 HC and 13 individuals with other demyelinating conditions (ODC) including multiple sclerosis (MS). Individuals with CIS separated into two groups, namely those with early (≤14 days post-diagnostic magnetic resonance imaging (MRI); n = 6) and late (≥27 days; n = 12) blood sampling. Transitional B cells were increased in the blood of CIS patients independently of when blood was taken. However, there were two time-dependent effects found in the late CIS group relative to HC, including decreased CD56bright NK cells, which correlated significantly with time since MRI, and increased CD141+ myeloid dendritic cell (mDC2) frequencies. Higher CD1c+ B cells and lower non-classical monocyte frequencies were characteristic of more recent demyelinating disease activity (ODC and early CIS). Analysing cell populations by time since symptoms (subjective) and diagnostic MRI (objective) may contribute to understanding CIS.

Frequency of Dendritic Cells and Their Expression of Costimulatory Molecules in Children with Autism Spectrum Disorders.

The aim of our study was to evaluate the frequencies of myeloid dendritic cells (mDCs) and plasmacytoid dendritic cells (pDCs) in children with ASD. Subjects were 32 children with ASD and 30 healthy children as controls. The numbers of mDCs and pDCs and the expression of CD86 and CD80 on the entire DCs were detected by flow cytometry. ASD children had significantly higher percentages of mDCs and pDCs when compared to controls. We found significant inverse relationships between serum 25-hydroxyvitamin D levels and the frequencies of mDCs and pDCs in autistic children. Our data suggested that DCs could play a role in the clinical course of ASD. The relationship of DCs to immune disorders in ASD remains to be determined.

CD36 receptor regulates malaria-induced immune responses primarily at early blood stage infection contributing to parasitemia control and resistance to mortality

In malaria, CD36 plays several roles, including mediating parasite sequestration to host organs, phagocytic clearance of parasites, and regulation of immunity. Although the functions of CD36 in parasite sequestration and phagocytosis have been clearly defined, less is known about its role in malaria immunity. Here, to understand the function of CD36 in malaria immunity, we studied parasite growth, innate and adaptive immune responses, and host survival in WT and Cd36-/- mice infected with a non-lethal strain of Plasmodium yoelii Compared with Cd36-/- mice, WT mice had lower parasitemias and were resistant to death. At early but not at later stages of infection, WT mice had higher circulatory proinflammatory cytokines and lower anti-inflammatory cytokines than Cd36-/- mice. WT mice showed higher frequencies of proinflammatory cytokine-producing and lower frequencies of anti-inflammatory cytokine-producing dendritic cells (DCs) and natural killer cells than Cd36-/- mice. Cytokines produced by co-cultures of DCs from infected mice and ovalbumin-specific, MHC class II-restricted α/β (OT-II) T cells reflected CD36-dependent DC function. WT mice also showed increased Th1 and reduced Th2 responses compared with Cd36-/- mice, mainly at early stages of infection. Furthermore, in infected WT mice, macrophages and neutrophils expressed higher levels of phagocytic receptors and showed enhanced phagocytosis of parasite-infected erythrocytes than those in Cd36-/- mice in an IFN-γ-dependent manner. However, there were no differences in malaria-induced humoral responses between WT and Cd36-/- mice. Overall, the results show that CD36 plays a significant role in controlling parasite burden by contributing to proinflammatory cytokine responses by DCs and natural killer cells, Th1 development, phagocytic receptor expression, and phagocytic activity.

Yersinia pseudotuberculosis supports Th17 differentiation and limits de novo regulatory T cell induction by directly interfering with T cell receptor signaling

Adaptive immunity critically contributes to control acute infection with enteropathogenic Yersinia pseudotuberculosis; however, the role of CD4+ T cell subsets in establishing infection and allowing pathogen persistence remains elusive. Here, we assessed the modulatory capacity of Y. pseudotuberculosis on CD4+ T cell differentiation. Using in vivo assays, we report that infection with Y. pseudotuberculosis resulted in enhanced priming of IL-17-producing T cells (Th17 cells), whereas induction of Foxp3+ regulatory T cells (Tregs) was severely disrupted in gut-draining mesenteric lymph nodes (mLNs), in line with altered frequencies of tolerogenic and proinflammatory dendritic cell (DC) subsets within mLNs. Additionally, by using a DC-free in vitro system, we could demonstrate that Y. pseudotuberculosis can directly modulate T cell receptor (TCR) downstream signaling within naïve CD4+ T cells and Tregs via injection of effector molecules through the type III secretion system, thereby affecting their functional properties. Importantly, modulation of naïve CD4+ T cells by Y. pseudotuberculosis resulted in an enhanced Th17 differentiation and decreased induction of Foxp3+ Tregs in vitro. These findings shed light to the adjustment of the Th17-Treg axis in response to acute Y. pseudotuberculosis infection and highlight the direct modulation of CD4+ T cell subsets by altering their TCR downstream signaling.