CD103+CD11b+ Dendritic Cells Induce Th17 T Cells in Muc2-Deficient Mice with Extensively Spread Colitis

Mucus alterations are a feature of ulcerative colitis (UC) and can drive inflammation by compromising the mucosal barrier to luminal bacteria. The exact pathogenesis of UC remains unclear, but CD4⁺ T cells reacting to commensal antigens appear to contribute to pathology. Given the unique capacity of dendritic cells (DCs) to activate naive T cells, colon DCs may activate pathogenic T cells and contribute to disease. Using Muc2^-/- mice, which lack a functional mucus barrier and develop spontaneous colitis, we show that colitic animals have reduced colon CD103⁺CD11b^- DCs and increased CD103^-CD11b⁺ phagocytes. Moreover, changes in colonic DC subsets and distinct cytokine patterns distinguish mice with distally localized colitis from mice with colitis spread proximally. Specifically, mice with proximally spread, but not distally contained, colitis have increased IL-1β, IL-6, IL-17, TNFα, and IFNγ combined with decreased IL-10 in the distal colon. These individuals also have increased numbers of CD103⁺CD11b⁺ DCs in the distal colon. CD103⁺CD11b⁺ DCs isolated from colitic but not noncolitic mice induced robust differentiation of Th17 cells but not Th1 cells ex vivo. In contrast, CD103^-CD11b⁺ DCs from colitic Muc2^-/- mice induced Th17 as well as Th1 differentiation. Thus, the local environment influences the capacity of intestinal DC subsets to induce T cell proliferation and differentiation, with CD103⁺CD11b⁺ DCs inducing IL-17-producing T cells being a key feature of extensively spread colitis.     

Astrocytes Modulate the Polarization of CD4+ T Cells to Th1 Cells

T-cell characteristics are dynamic and influenced by multiple factors. To test whether cells and the environment in the central nervous system (CNS) can influence T-cells, we tested if culturing mouse CD4⁺ T-cells on mouse primary astrocytes, compared with standard feeder cells, modified T-cell polarization to Th1 and Treg subtypes. Astrocytes supported the production of Th1 cells and Tregs, which was diminished by inflammatory activation of astrocytes, and glutamate accumulation that may result from impaired glutamate uptake by astrocytes strongly promoted Th1 production. These results demonstrate that astrocytes and the environment in the CNS have the capacity to regulate T-cell characteristics.     

Bordetella pertussis Commits Human Dendritic Cells to Promote a Th1/Th17 Response through the Activity of Adenylate Cyclase Toxin and MAPK-Pathways

The complex pathology of B. pertussis infection is due to multiple virulence factors having disparate effects on different cell types. We focused our investigation on the ability of B. pertussis to modulate host immunity, in particular on the role played by adenylate cyclase toxin (CyaA), an important virulence factor of B. pertussis. As a tool, we used human monocyte derived dendritic cells (MDDC), an ex vivo model useful for the evaluation of the regulatory potential of DC on T cell immune responses. The work compared MDDC functions after encounter with wild-type B. pertussis (BpWT) or a mutant lacking CyaA (BpCyaA−), or the BpCyaA− strain supplemented with either the fully functional CyaA or a derivative, CyaA*, lacking adenylate cyclase activity. As a first step, MDDC maturation, cytokine production, and modulation of T helper cell polarization were evaluated. As a second step, engagement of Toll-like receptors (TLR) 2 and TLR4 by B. pertussis and the signaling events connected to this were analyzed. These approaches allowed us to demonstrate that CyaA expressed by B. pertussis strongly interferes with DC functions, by reducing the expression of phenotypic markers and immunomodulatory cytokines, and blocking IL-12p70 production. B. pertussis-treated MDDC promoted a mixed Th1/Th17 polarization, and the activity of CyaA altered the Th1/Th17 balance, enhancing Th17 and limiting Th1 expansion. We also demonstrated that Th1 effectors are induced by B. pertussis-MDDC in the absence of IL-12p70 through an ERK1/2 dependent mechanism, and that p38 MAPK is essential for MDDC-driven Th17 expansion. The data suggest that CyaA mediates an escape strategy for the bacterium, since it reduces Th1 immunity and increases Th17 responses thought to be responsible, when the response is exacerbated, for enhanced lung inflammation and injury.     

TNF-alpha drives human CD14+ monocytes to differentiate into CD70+ dendritic cells evoking Th1 and Th17 responses

Many mechanisms involving TNF-alpha, Th1 responses, and Th17 responses are implicated in chronic inflammatory autoimmune disease. Recently, the clinical impact of anti-TNF therapy on disease progression has resulted in re-evaluation of the central role of this cytokine and engendered novel concept of TNF-dependent immunity. However, the overall relationship of TNF-alpha to pathogenesis is unclear. Here, we demonstrate a TNF-dependent differentiation pathway of dendritic cells (DC) evoking Th1 and Th17 responses. CD14(+) monocytes cultured in the presence of TNF-alpha and GM-CSF converted to CD14(+) CD1a(low) adherent cells with little capacity to stimulate T cells. On stimulation by LPS, however, they produced high levels of TNF-alpha, matrix metalloproteinase (MMP)-9, and IL-23 and differentiated either into mature DC or activated macrophages (M phi). The mature DC (CD83(+) CD70(+) HLA-DR (high) CD14(low)) expressed high levels of mRNA for IL-6, IL-15, and IL-23, induced naive CD4 T cells to produce IFN-gamma and TNF-alpha, and stimulated resting CD4 T cells to secret IL-17. Intriguingly, TNF-alpha added to the monocyte culture medium determined the magnitude of LPS-induced maturation and the functions of the derived DC. In contrast, the M phi (CD14(high)CD70(+)CD83(-)HLA-DR(-)) produced large amounts of MMP-9 and TNF-alpha without exogenous TNF stimulation. These results suggest that the TNF priming of monocytes controls Th1 and Th17 responses induced by mature DC, but not inflammation induced by activated M phi. Therefore, additional stimulation of monocytes with TNF-alpha may facilitate TNF-dependent adaptive immunity together with GM-CSF-stimulated M phi-mediated innate immunity.     

Expansion in CD39+ CD4+ Immunoregulatory T Cells and Rarity of Th17 Cells in HTLV-1 Infected Patients Is Associated with Neurological Complications

HTLV-1 infection is associated with several inflammatory disorders, including the neurodegenerative condition HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). It is unclear why a minority of infected subjects develops HAM/TSP. CD4⁺ T cells are the main target of infection and play a pivotal role in regulating immunity to HTLV and are hypothesized to participate in the pathogenesis of HAM/TSP. The CD39 ectonucleotidase receptor is expressed on CD4⁺ T cells and based on co-expression with CD25, marks T cells with distinct regulatory (CD39⁺CD25⁺) and effector (CD39⁺CD25⁻) function. Here, we investigated the expression of CD39 on CD4⁺ T cells from a cohort of HAM/TSP patients, HTLV-1 asymptomatic carriers (AC), and matched uninfected controls. The frequency of CD39⁺ CD4⁺ T cells was increased in HTLV-1 infected patients, regardless of clinical status. More importantly, the proportion of the immunostimulatory CD39⁺CD25⁻ CD4⁺ T-cell subset was significantly elevated in HAM/TSP patients as compared to AC and phenotypically had lower levels of the immunoinhibitory receptor, PD-1. We saw no difference in the frequency of CD39⁺CD25⁺ regulatory (Treg) cells between AC and HAM/TSP patients. However, these cells transition from being anergic to displaying a polyfunctional cytokine response following HTLV-1 infection. CD39⁻CD25⁺ T cell subsets predominantly secreted the inflammatory cytokine IL-17. We found that HAM/TSP patients had significantly fewer numbers of IL-17 secreting CD4⁺ T cells compared to uninfected controls. Taken together, we show that the expression of CD39 is upregulated on CD4⁺ T cells HAM/TSP patients. This upregulation may play a role in the development of the proinflammatory milieu through pathways both distinct and separate among the different CD39 T cell subsets. CD39 upregulation may therefore serve as a surrogate diagnostic marker of progression and could potentially be a target for interventions to reduce the development of HAM/TSP.     

Th1、Th2和Th17型细胞在类风湿性关节炎和系统性红斑狼疮中的活化特点

探讨Th1、Th2和Th17型细胞在类风湿性关节炎(RA)和系统性红斑狼疮(SLE)发病机制中的作用。收集37例RA患者、25例SLE患者和34例健康人的抗凝血,应用ELISA检测血清中IFN-γ、IL-10和IL-17的水平。与健康对照组比较,RA和SLE患者血清中IFN-γ的水平均具有统计学意义(P<0.05);SLE患者IL-10水平出现有意义的升高(P<0.05);而RA患者IL-17的升高具有统计学意义(P<0.05)。由此提示Th1、Th2和Th17细胞在自身免疫性疾病中均发挥不同的重要作用。     

Tc17 CD8+ T Cells Potentiate Th1-Mediated Autoimmune Diabetes in a Mouse Model

An increase in IL-17-producing CD8(+) T (Tc17) cells has been reported in the peripheral blood of children with recent onset type 1 diabetes (T1D), but their contribution to disease pathogenesis is still unknown. To directly study the pathogenic potential of β cell-specific Tc17 cells, we used an experimental model of T1D based on the expression of the neo-self Ag hemagglutinin (HA) in the β cells of the pancreas. When transferred alone, the IL-17-producing HA-specific CD8(+) T cells homed to the pancreatic lymph nodes without causing any pancreatic infiltration or tissue destruction. When transferred together with small numbers of diabetogenic HA-specific CD4(+) T cells, a strikingly different phenotype developed. Under these conditions, Tc17 cells sustained disease progression, driving the destruction of β-islet cells, causing hyperglycemia and ultimately death. Disease progression did not correlate with functional or numerical alterations among the HA-specific CD4(+) T cells. Rather, the transferred CD8(+) T cells accumulated in the pancreatic islets and a considerable fraction converted, under the control of IL-12, to an IFN-γ-producing phenotype. Our data indicate that Tc17 cells are not diabetogenic but can potentiate a Th1-mediated disease. Plasticity of the Tc17 lineage is associated with transition to overt disease in this experimental model of T1D.     

Differential Capacity of Human Skin Dendritic Cells to Polarize CD4+T Cells into IL-17, IL-21 and IL-22 Producing Cells

Accumulating evidence suggests a contribution of T cell-derived IL-17, IL-21 and IL-22 cytokines in skin immune homeostasis as well as inflammatory disorders. Here, we analyzed whether the cytokine-producing T lymphocytes could be induced by the different subsets of human skin dendritic cells (DCs), i.e., epidermal Langerhans cells (LCs), dermal CD1c⁺CD14⁻ and CD14⁺ DCs (DDCs). DCs were purified following a 2-day migration from separated epidermal and dermal sheets and co-cultured with allogeneic T cells before cytokine secretion was explored. Results showed that no skin DCs could induce substantial IL-17 production by naïve CD4⁺ or CD8⁺T lymphocytes whereas all of them could induce IL-17 production by memory T cells. In contrast, LCs and CD1c⁺CD14⁻DDCs were able to differentiate naïve CD4⁺T lymphocytes into IL-22 and IL-21-secreting cells, LCs being the most efficient in this process. Intracellular cytokine staining showed that the majority of IL-21 or IL-22 secreting CD4⁺T lymphocytes did not co-synthesized IFN-γ, IL-4 or IL-17. IL-21 and IL-22 production were dependent on the B7/CD28 co-stimulatory pathway and ICOS-L expression on skin LCs significantly reduced IL-21 level. Finally, we found that TGF-β strongly down-regulates both IL-21 and IL-22 secretion by allogeneic CD4⁺ T cells. These results add new knowledge on the functional specialization of human skin DCs and might suggest new targets in the treatment of inflammatory skin disorders.     

Fonsecaea pedrosoi Conidia Induces Activation of Dendritic Cells and Increases CD11c+ Cells in Regional Lymph Nodes During Experimental Chromoblastomycosis

The chromoblastomycosis is a subcutaneous mycosis with a high morbidity rate, Fonsecaea pedrosoi being the largest etiologic agent of this mycosis, usually confined to the skin and subcutaneous tissues. Rarely people get the cure, because the therapies shown to be deficient and few studies report the host–parasite relationship. Dendritic cells (DCs) are specialized in presenting antigens to naïve T lymphocytes inducing primary immune responses. Therefore, we propose to study the migratory capacity of DCs after infection with conidia of F. pedrosoi. The phenotype of DCs was evaluated using cells obtained from footpad and lymph nodes of BALB/c mice after 12, 24 and 72 h of infection. After 24 and 72 h of infection, we found a significant decrease in DCs in footpad and a significant increase in the lymph nodes after 72 h. The expression of surface markers and co-stimulatory molecules were reduced in cells obtained from footpad. To better assess the migratory capacity of DCs migration from footpad, CFSE-stained conidia were injected subcutaneously. We found that after 12 and 72 h, CD11c⁺ cells were increased in regional lymph nodes, leading us to believe that DCs (CD11c⁺) were able to phagocytic conidia present in footpad and migrated to regional lymph nodes.

     

Helminth Antigens Enable CpG-Activated Dendritic Cells to Inhibit the Symptoms of Collagen-induced Arthritis through Foxp3+ Regulatory T Cells

Dendritic cells (DC) have the potential to control the outcome of autoimmunity by modulating the immune response. In this study, we tested the ability of Fasciola hepatica total extract (TE) to induce tolerogenic properties in CpG-ODN (CpG) maturated DC, to then evaluate the therapeutic potential of these cells to diminish the inflammatory response in collagen induced arthritis (CIA). DBA/1J mice were injected with TE plus CpG treated DC (T/C-DC) pulsed with bovine collagen II (CII) between two immunizations with CII and clinical scores CIA were determined. The levels of CII-specific IgG2 and IgG1 in sera, the histological analyses in the joints, the cytokine profile in the draining lymph node (DLN) cells and in the joints, and the number, and functionality of CD4+CD25+Foxp3+ T cells (Treg) were evaluated. Vaccination of mice with CII pulsed T/C-DC diminished the severity and incidence of CIA symptoms and the production of the inflammatory cytokine, while induced the production of anti-inflammatory cytokines. The therapeutic effect was mediated by Treg cells, since the adoptive transfer of CD4+CD25+ T cells, inhibited the inflammatory symptoms in CIA. The in vitro blockage of TGF-β in cultures of DLN cells plus CII pulsed T/C-DC inhibited the expansion of Treg cells. Vaccination with CII pulsed T/C-DC seems to be a very efficient approach to diminish exacerbated immune response in CIA, by inducing the development of Treg cells, and it is therefore an interesting candidate for a cell-based therapy for rheumatoid arthritis (RA).     

C5a Regulates IL-12+DC Migration to Induce Pathogenic Th1 and Th17 Cells in Sepsis

Objective

It is well known that complement system C5a is excessively activated during the onset of sepsis. However, it is unclear whether C5a can regulate dentritic cells (DCs) to stimulate adaptive immune cells such as Th1 and Th17 in sepsis.

Methods

Sepsis was induced by cecal ligation and puncture (CLP). CLP-induced sepsis was treated with anti-C5a or IL-12. IL-12⁺DC, IFNγ⁺Th1, and IL-17⁺Th17 cells were analyzed by flow cytometry. IL-12 was measured by ELISA.

Results

Our studies here showed that C5a induced IL-12⁺DC cell migration from the peritoneal cavity to peripheral blood and lymph nodes. Furthermore, IL-12⁺DC cells induced the expansion of pathogenic IFNγ⁺Th1 and IL-17⁺Th17 cells in peripheral blood and lymph nodes. Moreover, IL-12, secreted by DC cells in the peritoneal cavity, is an important factor that prevents the development of sepsis.

Conclusion

Our data suggests that C5a regulates IL-12⁺DC cell migration to induce pathogenic Th1 and Th17 cells in sepsis.     

Co-Culture of Human Bronchial Fibroblasts and CD4+ T Cells Increases Th17 Cytokine Signature

Background

Airway inflammation is an important characteristic of asthma and has been associated with airway remodelling and bronchial hyperreactivity. The mucosal microenvironment composed of structural cells and highly specialised extracellular matrix is able to amplify and promote inflammation. This microenvironment leads to the development and maintenance of a specific adaptive response characterized by Th2 and Th17. Bronchial fibroblasts produce multiple mediators that may play a role in maintaining and amplifying this response in asthma.

Objective

To investigate the role of bronchial fibroblasts obtained from asthmatic subjects and healthy controls in regulating Th17 response by creating a local micro-environment that promotes this response in the airways.

Methods

Human bronchial fibroblasts and CD4⁺T cells were isolated from atopic asthmatics and non-atopic healthy controls. CD4⁺T were co-cultured with bronchial fibroblasts of asthmatic subjects and healthy controls. RORc gene expression was detected by qPCR. Phosphorylated STAT-3 and RORγt were evaluated by western blots. Th17 phenotype was measured by flow cytometry. IL-22, IL17, IL-6 TGF-β and IL1-β were assessed by qPCR and ELISA.

Results

Co-culture of CD4⁺T cells with bronchial fibroblasts significantly stimulated RORc expression and induced a significant increase in Th17 cells as characterized by the percentage of IL-17⁺/CCR6⁺ staining in asthmatic conditions. IL-17 and IL-22 were increased in both normal and asthmatic conditions with a significantly higher amount in asthmatics compared to controls. IL-6, IL-1β, TGF-β and IL-23 were significantly elevated in fibroblasts from asthmatic subjects upon co-culture with CD4⁺T cells. IL-23 stimulates IL-6 and IL-1β expression by bronchial fibroblasts.

Conclusion

Interaction between bronchial fibroblasts and T cells seems to promote specifically Th17 cells profile in asthma. These results suggest that cellular interaction particularly between T cells and fibroblasts may play a pivotal role in the regulation of the inflammatory response in asthma.     

Cytokines in the differentiation of Th1/Th2 CD4+ subsets in leishmaniasis

Leishmania major infect only macrophages in the host, where they reside in endolysosomal compartments into which MHC class II molecules co-localize. Experimental infection in mice has provided a useful model for the differentiation of Th1 CD4+ effector lymphocytes that are required for the generation of IFN-γ that activates the macrophage to a microbicidal state. Genetically susceptible BALB/c mice aberrantly activate Th2 CD4+ effector cells that are ineffective in arresting infection. Increasing evidence suggests that, rather than discrete parasite antigens or MHC molecules, cytokines mediate the critical decision in the developmental switch to either the Th1 or Th2 effector phenotype.     

Priming of Salmonella enterica Serovar Typhi-Specific CD8+ T Cells by Suicide Dendritic Cell Cross-Presentation in Humans

Background

The emergence of antibiotic-resistant strains of Salmonella enterica serovar Typhi (S. Typhi), the etiologic agent of typhoid fever, has aggravated an already important public health problem and added new urgency to the development of more effective typhoid vaccines. To this end it is critical to better understand the induction of immunity to S. Typhi. CD8⁺ T cells are likely to play an important role in host defense against S. Typhi by several effector mechanisms, including killing of infected cells and IFN-γ secretion. However, how S. Typhi regulates the development of specific CD8⁺ responses in humans remains unclear. Recent studies in mice have shown that dendritic cells (DC) can either directly (upon uptake and processing of Salmonella) or indirectly (by bystander mechanisms) elicit Salmonella-specific CD8⁺ T cells.

Methodology/Principal Findings

We report here that upon infection with live S. Typhi, human DC produced high levels of pro-inflammatory cytokines IL-6, IL-8 and TNF-α, but low levels of IL-12 p70 and IFN-γ. In contrast, DC co-cultured with S. Typhi-infected cells, through suicide cross-presentation, uptake S. Typhi-infected human cells and release high levels of IFN-γ and IL-12p70, leading to the subsequent presentation of bacterial antigens and triggering the induction of memory T cells, mostly CD3⁺CD8⁺CD45RA⁻CD62L⁻ effector/memory T cells.

Conclusions/Significance

This study is the first to demonstrate the effect of S. Typhi on human DC maturation and on their ability to prime CD8⁺ cells and highlights the significance of these phenomena in eliciting adaptive immunity to S. Typhi.     

Quantitative and Qualitative Deficits in Neonatal Lung-Migratory Dendritic Cells Impact the Generation of the CD8+ T Cell Response

CD103+ and CD11b+ populations of CD11c+MHCIIhi murine dendritic cells (DCs) have been shown to carry antigens from the lung through the afferent lymphatics to mediastinal lymph nodes (MLN). We compared the responses of these two DC populations in neonatal and adult mice following intranasal infection with respiratory syncytial virus. The response in neonates was dominated by functionally-limited CD103+ DCs, while CD11b+ DCs were diminished in both number and function compared to adults. Infecting mice at intervals through the first three weeks of life revealed an evolution in DC phenotype and function during early life. Using TCR transgenic T cells with two different specificities to measure the ability of CD103+ DC to induce epitope-specific CD8+ T cell responses, we found that neonatal CD103+ DCs stimulate proliferation in a pattern distinct from adult CD103+ DCs. Blocking CD28-mediated costimulatory signals during adult infection demonstrated that signals from this costimulatory pathway influence the hierarchy of the CD8+ T cell response to RSV, suggesting that limited costimulation provided by neonatal CD103+ DCs is one mechanism whereby neonates generate a distinct CD8+ T cell response from that of adults.     

Residual Endotoxin Contaminations in Recombinant Proteins Are Sufficient to Activate Human CD1c+ Dendritic Cells

Many commercially available recombinant proteins are produced in Escherichia coli, and most suppliers guarantee contamination levels of less than 1 endotoxin unit (EU). When we analysed commercially available proteins for their endotoxin content, we found contamination levels in the same range as generally stated in the data sheets, but also some that were higher. To analyse whether these low levels of contamination have an effect on immune cells, we stimulated the monocytic cell line THP-1, primary human monocytes, in vitro differentiated human monocyte-derived dendritic cells, and primary human CD1c⁺ dendritic cells (DCs) with very low concentrations of lipopolysaccharide (LPS; ranging from 0.002–2 ng/ml). We show that CD1c⁺ DCs especially can be activated by minimal amounts of LPS, equivalent to the levels of endotoxin contamination we detected in some commercially available proteins. Notably, the enhanced endotoxin sensitivity of CD1c⁺ DCs was closely correlated with high CD14 expression levels observed in CD1c⁺ DCs that had been maintained in cell culture medium for 24 hours. When working with cells that are particularly sensitive to LPS, even low endotoxin contamination may generate erroneous data. We therefore recommend that recombinant proteins be thoroughly screened for endotoxin contamination using the limulus amebocyte lysate test, fluorescence-based assays, or a luciferase based NF-κB reporter assay involving highly LPS-sensitive cells overexpressing TLR4, MD-2 and CD14.     

CD4+CD25+ regulatory T cells suppress differentiation and functions of Th1 and Th2 cells,Leishmania major infection,and colitis in mice

Regulatory T cells play a major role in modulating the immune response. However, most information on these cells centers on autoimmunity, and there is also considerable controversy on the functional characteristics of these cells. Here we provide direct in vitro and in vivo evidence that CD4+CD25+ regulatory T cells inhibit the differentiation and functions of both Th1 and Th2 cells. Importantly, CD4+CD25+ T cells suppressed the disease development of Leishmania major infection in SCID mice reconstituted with naive CD4+CD25- T cells. Furthermore, CD4+CD25+ T cells inhibited the development of colitis induced by both Th1 and Th2 cells in SCID mice. Our results therefore document that CD4+CD25+ regulatory T cells suppress both Th1 and Th2 cells and that these regulatory T cells have a profound therapeutic potential against diseases induced by both Th1 and Th2 cells in vivo.