Dectin-1 Controls TSLP-Induced Th2 Response by Regulating STAT3, STAT6, and p50-RelB Activities in Dendritic Cells.

The epithelium-associated cytokine thymic stromal lymphopoietin (TSLP) can induce OX40L and CCL17 expression by myeloid dendritic cells (mDCs), which contributes to aberrant Th2-type immune responses. Herein, we report that such TSLP-induced Th2-type immune response can be effectively controlled by Dectin-1, a C-type lectin receptor expressed by mDCs. Dectin-1 stimulation induced STAT3 activation and decreased the transcriptional activity of p50-RelB, both of which resulted in reduced OX40L expression on TSLP-activated mDCs. Dectin-1 stimulation also suppressed TSLP-induced STAT6 activation, resulting in decreased expression of the Th2 chemoattractant CCL17. We further demonstrated that Dectin-1 activation was capable of suppressing ragweed allergen (Amb a 1)-specific Th2-type T cell response in allergy patients ex vivo and house dust mite allergen (Der p 1)-specific IgE response in non-human primates in vivo. Collectively, this study provides a molecular explanation of Dectin-1-mediated suppression of Th2-type inflammatory responses and suggests Dectin-1 as a target for controlling Th2-type inflammation.

Whole blood transcriptional variations between responders and non-responders in asthma patients receiving omalizumab.

BACKGROUND: Anti-IgE (omalizumab) has been used for the treatment of moderate-to-severe asthma that is not controlled by inhaled steroids. Despite its success, it does not always provide patients with significant clinical benefits. OBJECTIVE: To investigate the transcriptional variations between omalizumab responders and non-responders and to study the mechanisms of action of omalizumab. METHODS: The whole blood transcriptomes of moderate-to-severe adult asthma patients (N = 45:34 responders and 11 non-responders) were analysed over the course of omalizumab treatment. Non-asthmatic healthy controls (N = 17) were used as controls. RESULTS: Transcriptome variations between responders and non-responders were identified using the genes significant (FDR < 0.05) in at least one comparison of each patient response status and time point compared with control subjects. Using gene ontology and network analysis, eight clusters of genes were identified. Longitudinal analyses of individual clusters revealed that responders could maintain changes induced with omalizumab treatment and become more similar to the control subjects, while non-responders tend to remain more similar to their pre-treatment baseline. Further analysis of an inflammatory gene cluster revealed that genes associated with neutrophil/eosinophil activities were up-regulated in non-responders and, more importantly, omalizumab did not significantly alter their expression levels. The application of modular analysis supported our findings and further revealed variations between responders and non-responders. CONCLUSION AND CLINICAL RELEVANCE: This study provides not only transcriptional variations between omalizumab responders and non-responders, but also molecular insights for controlling asthma by omalizumab.

Phenotypic and functional alterations of regulatory B cell subsets in adult allergic asthma patients.

BACKGROUND: IL-10-producing regulatory B cells (Bregs) are widely ascribed immune regulatory functions. However, Breg subsets in human asthma have not been fully investigated. OBJECTIVE: We studied Breg subsets in adult allergic asthma patients by assessing two major parameters, frequency and IL-10 expression. We then investigated factors that affect these two parameters in patients. METHODS: Peripheral blood mononuclear cells (PBMCs) of adult allergic asthma patients (N = 26) and non-asthmatic controls (N = 28) were used to assess the frequency of five subsets of transitional B cells (TBs), three subsets of CD24high CD27+ B cells and B1 cells. In addition to clinical data, IL-10 expression by individual Breg subsets was assessed by flow cytometry. RESULTS: Asthma patients had decreases of CD5+ and CD1d+ CD5+ , but an increase of CD27+ TBs which was significant in patients with moderate asthma (60 < FEV1 < 80). Regardless of asthma severity, there was no significant alteration in the frequencies of 6 other Breg subsets tested. However, we found that oral corticosteroid (OCS) significantly affected the frequency of Bregs in Breg subset-specific manners. OCS decreased CD5+ and CD1d+ CD5+ TBs, but increased CD27+ TBs and CD10+ CD24high CD27+ cells. Furthermore, OCS decreased IL-10 expression by CD27+ TBs, all 3 CD24high CD27+ B cell subsets (CD5+ , CD10+ and CD1d+ ) and B1 cells. OCS-mediated inhibition of IL-10 expression was not observed in the other Breg subsets tested. CONCLUSION & CLINICAL RELEVANCE: Alterations in the frequency of Bregs and their ability to express IL-10 are Breg subset-specific. OCS treatment significantly affects the frequency as well as their ability to express IL-10 in Breg subset-specific manners.

Clinical implications of CD4+ T cell subsets in adult atopic asthma patients.

BACKGROUND: T cells play a central role in chronic inflammation in asthma. However, the roles of individual subsets of T cells in the pathology of asthma in patients remain to be better understood. METHODS: We investigated the potential signatures of T cell subset phenotypes in asthma using fresh whole blood from adult atopic asthma patients (n = 43) and non-asthmatic control subjects (n = 22). We further assessed their potential clinical implications by correlating asthma severity. RESULTS: We report four major features of CD4+ T cells in the blood of atopic asthma patients. First, patients had a profound increase of CCR7+ memory CD4+ T cells, but not CCR7- memory CD4+ T cells. Second, an increase in CCR4+ CD4+ T cells in patients was mainly attributed to the increase of CCR7+ memory CD4+ T cells. Accordingly, the frequency of CCR4+CCR7+ memory CD4+ T cells correlated with asthma severity. Current common asthma therapeutics (including corticosteroids) were not able to affect the frequency of CCR4+CCR7+ memory CD4+ T cell subsets. Third, patients had an increase of Tregs, as assessed by measuring CD25, Foxp3, IL-10 and CTLA-4 expression. However, asthma severity was inversely correlated only with the frequency of CTLA-4+ CD4+ T cells. Lastly, patients and control subjects have similar frequencies of CD4+ T cells that express CCR5, CCR6, CXCR3, CXCR5, CD11a, or α4 integrin. However, the frequency of α4+ CD4+ T cells in patients correlated with asthma severity. CONCLUSIONS: CCR4+CCR7+ memory, but not CCR4+CCR7- memory, α4+, and CTLA4+ CD4+ T cells in patients show significant clinical implications in atopic asthma. Current common therapeutics cannot alter the frequency of such CD4+ T cell subsets in adult atopic asthma patients.

Differential Effects of Inflammation on Bone and Response to Biologics in Rheumatoid Arthritis and Spondyloarthritis.

PURPOSE OF REVIEW: We review the pathways, cytokines, and concepts important to the pathogenesis of bone resorption and formation in rheumatoid arthritis (RA) and spondyloarthritis (SpA). RECENT FINDINGS: Research in bone biology has shed light on the pathogenesis of the joint destruction that occurs in RA and in peripheral SpA. However, understanding the mechanisms behind the bone formation seen in peripheral and axial SpA has been challenging. Mouse models have been used to gain an understanding of key signaling pathways, cytokines and cells regulating inflammation in these diseases. Biologic therapies directed against these targets have been developed to control both inflammation and effects on bone. Although biologic therapies improve joint inflammation in both RA and SpA, leading to a decrease in pain and improving quality of life for patients, the long-term effects of such therapies must also be evaluated by assessing their impact on structural progression. Inhibition of radiographic progression in both RA and peripheral SpA has been easier to demonstrate than in axial SpA. Here, we discuss the similarities and differences among biologic therapies as they pertain to radiographic progression.

Synthesis and immunostimulatory activity of substituted TLR7 agonists.

Fifteen new substituted adenines were synthesized as potential TLR7 agonists. These compounds, along with 9 previously reported compounds, were analyzed for TLR7 activity and for the selective stimulation of B cell proliferation. Several functionalized derivatives exhibit significant activity, suggesting their potential for use as vaccine adjuvants.

Dectin-1 in the control of Th2-type T cell responses.

Dendritic cells (DCs) are major antigen-presenting cells (APCs) that can induce and control host immune responses. DCs express pattern recognition receptors (PRRs), which can translate external and internal triggers into different types of T cell responses. The types of CD4+ T cell responses elicited by DCs (e.g., Th1, Th2, Th17, Th21, Th22 and regulatory T cells (Tregs)) are associated with either host immunity or inflammatory diseases, including allergic diseases and autoimmune diseases. In particular, the pathogenic functions of Th2-type T cells in allergic immune disorders have been well documented, although Th2-type T cell responses are crucial for immunity against certain parasite infections. Recent evidence also indicates that the inflammatory Th2 signatures in cancers, including breast and pancreatic cancers, are highly associated with poor clinical outcomes in patients. It is thus important to find cellular/molecular targets expressed in DCs that control such inflammatory Th2-type T cell responses. In a recent paper published in The Journal of Immunology, we demonstrated that Dectin-1 expressed on the two major human DC subsets, myeloid DCs (mDCs) and plasmacytoid DCs (pDCs), has opposing roles in the control of Th2-type CD4+ T cell responses. Dectin-1 expressed on mDCs decreases Th2-type CD4+ T cell responses, while Dectin-1 expressed on pDCs favors Th2-type CD4+ T cell responses. This finding expands our understanding of the roles of DCs and Dectin-1 expressed on DCs in the pathogenesis of Th2-associated diseases and in host immunity to microbial infections and cancers.

Functional Specialty of CD40 and Dendritic Cell Surface Lectins for Exogenous Antigen Presentation to CD8(+) and CD4(+) T Cells.

Dendritic cells (DCs) are major antigen-presenting cells that can efficiently prime and cross-prime antigen-specific T cells. Delivering antigen to DCs via surface receptors is thus an appealing strategy to evoke cellular immunity. Nonetheless, which DC surface receptor to target to yield the optimal CD8(+) and CD4(+) T cell responses remains elusive. Herein, we report the superiority of CD40 over 9 different lectins and scavenger receptors at evoking antigen-specific CD8(+) T cell responses. However, lectins (e.g., LOX-1 and Dectin-1) were more efficient than CD40 at eliciting CD4(+) T cell responses. Common and distinct patterns of subcellular and intracellular localization of receptor-bound αCD40, αLOX-1 and αDectin-1 further support their functional specialization at enhancing antigen presentation to either CD8(+) or CD4(+) T cells. Lastly, we demonstrate that antigen targeting to CD40 can evoke potent antigen-specific CD8(+) T cell responses in human CD40 transgenic mice. This study provides fundamental information for the rational design of vaccines against cancers and viral infections.

New TLR7 agonists with improved humoral and cellular immune responses.

Toll-like receptor 7 (TLR7) agonists are of interest as vaccine adjuvants and cancer therapeutics. Therefore, development of new TLR7 agonists that can efficiently promote host immune responses without evoking side effects is of great importance. Here, we describe two new compounds, J4 and F4, which elicit intracellular signaling exclusively via TLR7. Interestingly, both J4 and F4 induced less cytokine secretion (IL-1ß, IL-6, IL-10, IL-12p40, TNFα, and IL-12p70) from myeloid dendritic cells (mDCs) and monocytes than CL075 and R848; however, they all generated similar levels of phenotype maturation of antigen presenting cells (APCs), including plasmacytoid DCs. We further found that J4- and F4-induced APC activation was largely dependent on the activation of NF-κB and p38. Lastly, J4 and F4 could efficiently promote B cell proliferation and plasmablast differentiation as well as antigen-specific CD8(+) T cell responses in human in vitro. Therefore, these new TLR7 agonists could be employed to facilitate the development of new therapeutics and vaccine adjuvants against cancers and microbial infections.

Opposing Roles of Dectin-1 Expressed on Human Plasmacytoid Dendritic Cells and Myeloid Dendritic Cells in Th2 Polarization.

Dendritic cells (DCs) can induce and control host immune responses. DC subset-dependent functional specialties and their ability to display functional plasticity, which is mainly driven by signals via pattern recognition receptors, identify DCs as immune orchestrators. A pattern recognition receptor, Dectin-1, is expressed on myeloid DCs and known to play important roles in Th17 induction and activation during fungal and certain bacterial infections. In this study, we first demonstrate that human plasmacytoid DCs express Dectin-1 in both mRNA and protein levels. More interestingly, Dectin-1-activated plasmacytoid DCs promote Th2-type T cell responses, whereas Dectin-1-activated myeloid DCs decrease Th2-type T cell responses. Such contrasting outcomes of Th2-type T cell responses by the two DC subsets are mainly due to their distinct abilities to control surface OX40L expression in response to ß-glucan. This study provides new insights for the regulation of host immune responses by Dectin-1 expressed on DCs.

Facile syntheses of functionalized toll-like receptor 7 agonists.

Protein conjugates of toll-like receptor 7 agonists have been shown to elicit powerful immune responses. In order to facilitate our studies in this area our group has developed efficient syntheses for a number of functionalized derivatives that retain immune stimulatory activity.

C-type lectin-like receptor LOX-1 promotes dendritic cell-mediated class-switched B cell responses.

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a pattern-recognition receptor for a variety of endogenous and exogenous ligands. However, LOX-1 function in the host immune response is not fully understood. Here, we report that LOX-1 expressed on dendritic cells (DCs) and B cells promotes humoral responses. On B cells LOX-1 signaling upregulated CCR7, promoting cellular migration toward lymphoid tissues. LOX-1 signaling on DCs licensed the cells to promote B cell differentiation into class-switched plasmablasts and led to downregulation of chemokine receptor CXCR5 and upregulation of chemokine receptor CCR10 on plasmablasts, enabling their exit from germinal centers and migration toward local mucosa and skin. Finally, we found that targeting influenza hemagglutinin 1 (HA1) subunit to LOX-1 elicited HA1-specific protective antibody responses in rhesus macaques. Thus, LOX-1 expressed on B cells and DC cells has complementary functions to promote humoral immune responses.

Induction and activation of human Th17 by targeting antigens to dendritic cells via dectin-1.

Recent compelling evidence indicates that Th17 confer host immunity against a variety of microbes, including extracellular and intracellular pathogens. Therefore, understanding mechanisms for the induction and activation of Ag-specific Th17 is important for the rational design of vaccines against pathogens. To study this, we employed an in vitro system in which influenza hemagglutinin (HA) 1 was delivered to dendritic cells (DCs) via Dectin-1 using anti-human Dectin-1 (hDectin-1)-HA1 recombinant fusion proteins. We found that healthy individuals maintained broad ranges of HA1-specific memory Th17 that were efficiently activated by DCs targeted with anti-hDectin-1-HA1. Nonetheless, these DCs were not able to induce a significant level of HA1-specific Th17 responses even in the presence of the Th17-promoting cytokines IL-1ß and IL-6. We further found that the induction of surface IL-1R1 expression by signals via TCRs and common γ-chain receptors was essential for naive CD4(+) T cell differentiation into HA1-specific Th17. This process was dependent on MyD88, but not IL-1R-associated kinase 1/4. Thus, interruptions in STAT3 or MyD88 signaling led to substantially diminished HA1-specific Th17 induction. Taken together, the de novo generation of pathogen-specific human Th17 requires complex, but complementary, actions of multiple signals. Data from this study will help us design a new and effective vaccine strategy that can promote Th17-mediated immunity against microbial pathogens.

Dendritic cells and vaccine design for sexually-transmitted diseases.

Dendritic cells (DCs) are major antigen presenting cells (APCs) that can initiate and control host immune responses toward either immunity or tolerance. These features of DCs, as immune orchestrators, are well characterized by their tissue localizations as well as by their subset-dependent functional specialties and plasticity. Thus, the level of protective immunity to invading microbial pathogens can be dependent on the subsets of DCs taking up microbial antigens and their functional plasticity in response to microbial products, host cellular components and the cytokine milieu in the microenvironment. Vaccines are the most efficient and cost-effective preventive medicine against infectious diseases. However, major challenges still remain for the diseases caused by sexually-transmitted pathogens, including HIV, HPV, HSV and Chlamydia. We surmise that the establishment of protective immunity in the female genital mucosa, the major entry and transfer site of these pathogens, will bring significant benefit for the protection against sexually-transmitted diseases. Recent progresses made in DC biology suggest that vaccines designed to target proper DC subsets may permit us to establish protective immunity in the female genital mucosa against sexually-transmitted pathogens.

Evolution of treatment for rheumatoid arthritis.

Treatment for RA has changed profoundly over the past 25 years, evolving from a strategy of providing symptomatic relief, to implementation of therapeutic regimens that impact disease activity and ultimately have been shown to slow or arrest structural joint damage. Drug therapy for RA has evolved from salicylates, to NSAIDs, CSs, DMARDs, MTX, and finally to biologic response modifiers. MTX has become the initial drug of choice in most patients with RA, and some do well on MTX monotherapy without the addition of other agents. Combination regimens including MTX and other conventional DMARDs may be an effective early approach to treatment of RA. The biologic response modifiers (biologics) became available in the late 1990s, based on our understanding of the molecular mediators of synovial inflammation in RA. The first biologics inhibited TNF-α, a cytokine active in host defences against some infections and malignancies, but which also promotes inflammation and bone erosion. Inhibitors of TNF-α are mostly given with MTX, although some can be given as monotherapy. Studies consistently show that combination MTX + TNF-α inhibitor therapy leads to better outcomes than with either agent alone. Tight control strategies, employing objective measures, also lead to improved outcomes. When patients fail treatment with one or more TNF-α inhibitor + MTX, a number of other possible alternatives may be tried, including treatment with biologics having other mechanisms, such as antibodies to certain ILs, other cytokines and inflammatory mediators. Current therapy for RA is such that progression from symptom onset to significant disability is now no longer inevitable, and RA patients can anticipate comfortable and productive lives on medical therapy.

ACR/EULAR 2010 rheumatoid arthritis classification criteria.

Advances in our understanding of the pathogenesis of RA over the past two decades, particularly the identification of cytokines that promote synovial inflammation (e.g. TNF-α, IL-1 and IL-6), have led to treatment courses that affect the disease process itself, beyond alleviation of symptoms. In turn, emphasis has shifted to intervention early enough in the disease course to prevent the joint destruction that follows inflammation. Accordingly, in 2010 the ACR and the European League Against Rheumatism (EULAR) put forward revised classification criteria emphasizing RA characteristics that emerge early in the disease course, including ACPAs, a biomarker that predicts aggressive disease. These were in contrast with the 1987 ARA criteria, which distinguished established RA patients from those with other forms of arthritis, and identified patients with later disease. The categories of the 2010 ACR/EULAR criteria are grouped into four classifications, with point scores for each: joint symptoms; serology (including RF and/or ACPA); symptom duration, whether <6 weeks or >6 weeks; and acute-phase reactants (CRP and/or ESR). The criteria were developed in a three-phase process, beginning with an analysis of patient cohorts to determine what disease characteristics had persuaded clinicians to initiate MTX therapy, followed by consensus-based decisions and the creation of a scoring system that would predict which patients would go on to develop persistent and/or erosive disease.

2010 Rheumatoid arthritis classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative.

OBJECTIVE: The 1987 American College of Rheumatology (ACR; formerly, the American Rheumatism Association) classification criteria for rheumatoid arthritis (RA) have been criticized for their lack of sensitivity in early disease. This work was undertaken to develop new classification criteria for RA. METHODS: A joint working group from the ACR and the European League Against Rheumatism developed, in 3 phases, a new approach to classifying RA. The work focused on identifying, among patients newly presenting with undifferentiated inflammatory synovitis, factors that best discriminated between those who were and those who were not at high risk for persistent and/or erosive disease--this being the appropriate current paradigm underlying the disease construct "rheumatoid arthritis." RESULTS: In the new criteria set, classification as "definite RA" is based on the confirmed presence of synovitis in at least 1 joint, absence of an alternative diagnosis that better explains the synovitis, and achievement of a total score of 6 or greater (of a possible 10) from the individual scores in 4 domains: number and site of involved joints (score range 0-5), serologic abnormality (score range 0-3), elevated acute-phase response (score range 0-1), and symptom duration (2 levels; range 0-1). CONCLUSION: This new classification system redefines the current paradigm of RA by focusing on features at earlier stages of disease that are associated with persistent and/or erosive disease, rather than defining the disease by its late-stage features. This will refocus attention on the important need for earlier diagnosis and institution of effective disease-suppressing therapy to prevent or minimize the occurrence of the undesirable sequelae that currently comprise the paradigm underlying the disease construct "rheumatoid arthritis."

The 2010 American College of Rheumatology/European League Against Rheumatism classification criteria for rheumatoid arthritis: Phase 2 methodological report.

OBJECTIVE: The American College of Rheumatology and the European League Against Rheumatism have developed new classification criteria for rheumatoid arthritis (RA). The aim of Phase 2 of the development process was to achieve expert consensus on the clinical and laboratory variables that should contribute to the final criteria set. METHODS: Twenty-four expert RA clinicians (12 from Europe and 12 from North America) participated in Phase 2. A consensus-based decision analysis approach was used to identify factors (and their relative weights) that influence the probability of "developing RA," complemented by data from the Phase 1 study. Patient case scenarios were used to identify and reach consensus on factors important in determining the probability of RA development. Decision analytic software was used to derive the relative weights for each of the factors and their categories, using choice-based conjoint analysis. RESULTS: The expert panel agreed that the new classification criteria should be applied to individuals with undifferentiated inflammatory arthritis in whom at least 1 joint is deemed by an expert assessor to be swollen, indicating definite synovitis. In this clinical setting, they identified 4 additional criteria as being important: number of joints involved and site of involvement, serologic abnormality, acute-phase response, and duration of symptoms in the involved joints. These criteria were consistent with those identified in the Phase 1 data-driven approach. CONCLUSION: The consensus-based, decision analysis approach used in Phase 2 complemented the Phase 1 efforts. The 4 criteria and their relative weights form the basis of the final criteria set.