Thrombospondin-1 (TSP1)-producing B cells restore antigen (Ag)-specific immune tolerance in an allergic environment

Emerging functions of thrombospondin-1 in immunity

Thrombospondin-1 is a secreted matricellular glycoprotein that modulates cell behavior by interacting with components of the extracellular matrix and with several cell surface receptors. Its presence in the extracellular matrix is induced by injuries that cause thrombospondin-1 release from platelets and conditions including hyperglycemia, ischemia, and aging that stimulate its expression by many cell types. Conversely, rapid receptor-mediated clearance of thrombospondin-1 from the extracellular space limits its sustained presence in the extracellular space and maintains sub-nanomolar physiological concentrations in blood plasma. Roles for thrombospondin-1 signaling, mediated by specific cellular receptors or by activation of latent TGFβ, have been defined in T and B lymphocytes, natural killer cells, macrophages, neutrophils, and dendritic cells. In addition to regulating physiological nitric oxide signaling and responses of cells to stress, studies in mice lacking thrombospondin-1 or its receptors have revealed important roles for thrombospondin-1 in regulating immune responses in infectious and autoimmune diseases and antitumor immunity.

Tolerating CD47

Cluster of differentiation 47 (CD47) occupies the outer membrane of human cells, where it binds to soluble and cell surface receptors on the same and other cells, sculpting their topography and resulting in a pleiotropic receptor-multiligand interaction network. It is a focus of drug development to temper and accentuate CD47-driven immune cell liaisons, although consideration of on-target CD47 effects remain neglected. And yet, a late clinical trial of a CD47-blocking antibody was discontinued, existent trials were restrained, and development of CD47-targeting agents halted by some pharmaceutical companies. At this point, if CD47 can be exploited for clinical advantage remains to be determined. Herein an airing is made of the seemingly conflicting actions of CD47 that reflect its position as a junction connecting receptors and signalling pathways that impact numerous human cell types. Prospects of CD47 boosting and blocking are considered along with potential therapeutic implications for autoimmune diseases and cancer.

Thrombospondin-1, Platelet Factor 4, and Galectin-1 are Associated with Engraftment in Patients with Sickle Cell Disease Who Underwent Haploidentical HSCT

Sickle cell disease (SCD) is an inherited red blood cell disorder that leads to significant morbidity and early mortality. The most widely available curative approach remains allogeneic hematopoietic stem cell transplantation (HSCT). HLA-haploidentical (haplo) HSCT expands the donor pool considerably and is a practical alternative for these patients, but traditionally with an increased risk of allograft rejection. Biomarkers in patient plasma could potentially help predict HSCT outcome and allow treatment at an early stage to reverse or prevent graft rejection. Reliable, noninvasive methods to predict engraftment or rejection early after HSCT are needed. We sought to detect variations in the plasma proteomes of patients who engrafted compared with those who rejected their grafts. We used a mass spectrometry-based proteomics approach to identify candidate biomarkers associated with engraftment and rejection by comparing plasma samples obtained from 9 engrafted patients and 10 patients who experienced graft rejection. A total of 1378 proteins were identified, 45 of which were differentially expressed in the engrafted group compared with the rejected group. Based on bioinformatics analysis results, information from the literature, and immunoassay availability, 7 proteins-thrombospondin-1 (Tsp-1), platelet factor 4 (Pf-4), talin-1, moesin, cell division control protein 42 homolog (CDC42), galectin-1 (Gal-1), and CD9-were selected for further analysis. We compared these protein concentrations among 35 plasma samples (engrafted, n = 9; rejected, n = 10; healthy volunteers, n = 8; nontransplanted SCD, n = 8). ELISA analysis confirmed the significant up-regulation of Tsp-1, Pf-4, and Gal-1 in plasma samples from engrafted patients compared with rejected patients, healthy African American volunteers, and the nontransplanted SCD group (P < .01). By receiver operating characteristic analysis, these 3 proteins distinguished engrafted patients from the other groups (area under the curve, >0.8; P < .05). We then evaluated the concentration of these 3 proteins in samples collected pre-HSCT and at days +30, +60, +100, and +180 post-HSCT. The results demonstrate that Tsp-1 and Pf-4 stratified engrafted patients as early as day 60 post-HSCT (P < .01), and that Gal-1 was significantly higher in engrafted patients as early as day 30 post-HSCT (P < .01). We also divided the rejected group into those who experienced primary (n = 5) and secondary graft rejection (n = 5) and found that engrafted patients had significantly higher Tsp-1 levels compared with patients who developed primary graft rejection at days +60 and +100 (P < .05), as well as higher Pf-4 levels compared with patients who developed primary graft rejection at post-transplantation (PT) day 100. Furthermore, Tsp-1 levels were significantly higher at PT days 60 and 100 and Pf-4 levels were higher at PT day 100 in engrafted patients compared with those who experienced secondary graft rejection. Increased concentrations of plasma Gal-1, Tsp-1, and Pf-4 could reflect increased T regulatory cells, IL-10, and TGF-β, which are essential players in the initiation of immunologic tolerance. These biomarkers may provide opportunities for preemptive intervention to minimize the incidence of graft rejection.

TGF-β-secreting regulatory B cells: unsung players in immune regulation

Regulatory B cells contribute to the regulation of immune responses in cancer, autoimmune disorders, allergic conditions and inflammatory diseases. Although most studies focus on regulatory B lymphocytes expressing interleukin-10, there is growing evidence that B cells producing transforming growth factor β (TGF-β) can also regulate T-cell immunity in inflammatory diseases and promote the emergence of regulatory T cells that contribute to the induction and maintenance of natural and induced immune tolerance. Most research on TGF-β⁺ regulatory B cells has been conducted in models of allergy, cancer and autoimmune diseases, but there has, as yet, been limited scrutiny of their role in the transplant setting. Herein, we review recent investigations seeking to understand how TGF-β-producing B cells direct the immune response in various inflammatory diseases and whether these regulatory cells may have a role in fostering tolerance in transplantation.

Sublingual Immunotherapy: How Sublingual Allergen Administration Heals Allergic Diseases; Current Perspective about the Mode of Action

Owing to the successful application of sublingual immunotherapy (SLIT), allergen immunotherapy (AIT) has become one of the leading treatments for allergic diseases. Similar to the case with other AITs, such as subcutaneous and oral immunotherapies, not only the alleviation of allergic symptoms, but also the curing of the diseases can be expected in patients undergoing SLIT. However, how and why such strong efficacy is obtained by SLIT, in which allergens are simply administered under the tongue, is not clearly known. Various potential mechanisms, including the induction of blocking antibodies, T cell tolerance, regulatory B and T cells, CD103^-CD11b⁺ classical dendritic cells, and CD206⁺ macrophages, and the reduction of innate lymphoid cells, mast cells, and basophils, have been suggested. Recently, through a comparative analysis between high- and non-responder patients of SLIT, we have successfully proposed several novel mechanisms. Here, we introduce our recent findings and summarize the current understanding of the mechanisms underlying the strong efficacy of SLIT.

B cells and the microbiota: a missing connection in food allergy

Food allergies are a major public health concern due to their widespread and rising prevalence. The increase in food allergy is partially due to Western lifestyle habits which deplete protective commensal microbiota. These microbial perturbations can result in adverse host-microbe interactions, altering the phenotype of various immune cells and instigating allergic sensitization. Although B cells are critical to allergic pathology, microbial influences on B cells have been somewhat overlooked. Here, we focus on direct and indirect interactions between bacteria and B cells and how such interactions regulate B-cell phenotype, namely antibody production (IgA, IgE, IgG1, and IgG4) and regulatory B-cell (Breg) function. Understanding how microbes modulate B-cell activity in the context of food allergies is critical to both tracing the development of disease and assessing future treatment options.

Heterogeneous subsets of B-lineage regulatory cells (Breg cells)

B cells represent a key cellular component of humoral immunity. Besides antigen presentation and antibody production, B cells also play a role in immune regulation and induction of tolerance through several mechanisms. Our understanding of B-lineage cells with regulatory ability has been revolutionized by the delineation of heterogeneous subsets of these cells. Specific environmental signals may further determine the polarization and function of B-lineage regulatory cells. With the availability of new genetic, molecular and pharmacological tools, considerable advances have been made toward our understanding of the surface phenotype, developmental processes and functions of these cells. These exciting discoveries, some of which are still controversial, also raise many new questions, which makes the inhibitory function of B cells a rapidly growing field in immunopathology. Here we review highlights of the regulatory activity of B cells and the recent advances in the function and phenotype of these B-cell subsets in healthy and diseased states.

A20 Restores Impaired Intestinal Permeability and Inhibits Th2 Response in Mice with Colitis

BACKGROUND/AIMS

The etiology of inflammatory bowel disease is multifactorial and still obscure. The protective role of ubiquitin E3 ligase A20 (A20) in colitis needs to be further elucidated. This study aimed to investigate whether A20 exogenous administration restored impaired intestinal permeability and inhibited T helper (Th)2 response in mice with colitis.

METHODS

The effect of A20 overexpression in colonic mucosa on epithelial barrier function and T cell differentiation was evaluated in mice with dextran sulfate sodium (DSS)-induced chronic colitis.

RESULTS

A20 rectal treatment alleviated DSS-induced chronic colitis and restored impaired intestinal permeability. Oral challenge with 2% DSS elicited a Th2-type response in mice with colitis, and A20 rectal treatment inhibited CD4⁺ interleukin (IL)-4⁺ T cell differentiation and proliferation. In addition, the RNA expressions of Th2-related costimulatory molecular T-cell immunoglobulin and mucin domain (TIM)-1 and IL-4 were suppressed, while thrombospondin (TSP)-1 and interferon (IFN)-γ expressions were upregulated, after A20 rectal administration.

CONCLUSION

A20 rectal treatment restores impaired intestinal permeability and inhibits activated Th2 cell response in mice with colitis.

Genetics and epigenetics of allergy

PURPOSE OF REVIEW

Allergic diseases are prototypic examples for gene × environment-wide interactions. This review considers the current evidence for genetic and epigenetic mechanisms in allergic diseases and highlights barriers and facilitators for the implementation of these novel tools both for research and clinical practice.

RECENT FINDINGS

The value of whole-genome sequencing studies and the use of polygenic risk score analysis in homogeneous well characterized populations are currently being tested. Epigenetic mechanisms are known to play a crucial role in the pathogenesis of allergic disorders, especially through mediating the effects of the environmental factors, well recognized risk modifiers. There is emerging evidence for the immune-modulatory role of probiotics through epigenetic changes. Direct or indirect targeting of epigenetic mechanisms affect expression of the genes favouring the development of allergic diseases and can improve tissue biology. The ability to specifically edit the epigenome, especially using the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 technology, holds the promise of enhancing understanding of how epigenetic modifications function and enabling manipulation of cell phenotype for research or therapeutic purposes.

SUMMARY

Additional research in the role of genetic and epigenetic mechanisms in relation to allergic diseases' endotypes is needed. An international project characterizing the human epigenome in relation to allergic diseases is warranted.

Probiotics ingestion prevents HDAC11-induced DEC205+ dendritic cell dysfunction in night shift nurses

It is known that the day-night shift-rotation has a negative impact on the immune system. The underlying mechanism remains to be further investigated. Probiotics have regulatory effects on immune functions. This study aims to investigate the role of probiotic ingestion in preventing the DEC205⁺ dendritic cell (decDC) dysfunction in day-night shift-engaging nurses. In this study, blood samples were collected from day-night shift-rotating nurses who took or did not take yogurt (containing C. Butyricum) during the night shift (NS). decDC functions were evaluated with pertinent immunological approaches. We observed that the immune tolerogenic functions and interleukin (IL)-10 expression were impaired in decDCs of nurses after NS. HDAC11 was detected in decDCs that was markedly up regulated after NS. The HDAC11 levels were negatively correlated with the immune tolerogenic functions in decDCs. Ingestion of probiotic-containing yogurt during NS efficiently suppressed Bmal1 and HDAC11 levels as well as up regulated the immune regulatory functions in decDCs. In conclusion, NS has a negative impact on decDC immune tolerogenic functions, which can be prevented by ingesting probiotics-containing yogurt during NS.

Vasoactive intestinal peptide alleviates food allergy via restoring regulatory B cell functions

The immune regulatory cell dysfunction is associated with many immune diseases including food allergy (FA). This study aims to investigate the role of vasoactive intestinal peptide (VIP) in the maintenance of regulatory B cell (Br cell)'s immune suppressive functions by stabilizing thrombospondin (TSP1) expression. In this study, blood samples were collected from patients with food allergy (FA) and healthy control (HC) subjects. Br cells were isolated from the samples through flow cytometry cell sorting and analyzed by immunological approaches to determine the immune regulatory capacity. We found that the immune suppressive functions of Br cells were impaired in FA patients. The serum VIP levels were associated with the production of immune suppressive function-related mediators (interleukin-10, IL-10) of Br cells in FA patients. VIP counteracted IL-10 mRNA decay in Br cells by up regulating the TSP1 expression. TSP1 inhibited tristetraprolin (TTP) to prevent IL-10 mRNA decay in Br cells. Administration of VIP inhibited FA response through restoration of immune suppressive functions in Br cells. In conclusion, administration of VIP can alleviate FA response through up regulating expression of TSP1 to stabilize IL-10 expression in FA Br cells and recover the immune regulatory functions. The results have translational potential for the treatment of FA and other disorders associated with immune regulatory dysfunction of Br cells.

Histone deacetylase 11 inhibits interleukin 10 in B cells of subjects with allergic rhinitis

BACKGROUND

The interleukin (IL)-10 expression in B cells plays an important role in immune tolerance. The regulation of IL-10 expression in B cells is not fully understood yet. Tumor necrosis factor (TNF) is increased in allergic rhinitis (AR) patients. This study tests a hypothesis that TNF enhances histone deacetylase (HDAC)11 expression to inhibit the expression of IL-10 in B cells of AR patients.

METHODS

Peripheral B cells were collected from healthy persons and patients with AR. The B cells were analyzed by immune assay and molecular biological approaches for the expression of IL-10.

RESULTS

The expression of HDAC11 was higher in B cells of patients with AR than that in healthy persons. The expression of IL-10 in B cells was lower in AR patients than that in healthy subjects. The levels of HDAC11 in B cells were negatively correlated with the levels of IL-10. Exposure of B cells to TNF in the culture inhibited the expression of IL-10, in which HDAC11 played a critical role in the interference with the Il10 gene transcription. Inhibition of HDAC11 restored the IL-10 expression in B cells from AR patients and attenuated the experimental AR.

CONCLUSION

TNF can suppress the expression of IL-10 in B cells via enhancing the expression of HDAC11. Inhibition of HDAC11 restores the IL-10 expression in B cells of AR subjects. HDAC11 may be a novel target for the treatment of AR.

Vitamin D receptor interacts with NLRP3 to restrict the allergic response

Vitamin D receptor (VDR) mediates various biochemical activities between the cytoplasm and the nucleus in the cell. The nucleotide-binding, oligomerization domain (NOD)-like receptor family, pyrin domain containing 3 (NLRP3) protein is involved in the T helper type 2 (Th2) response. This study tests a hypothesis that VDR interacts with NLRP3 to restrict the Th2-biased response. In this study, VDR^-/- mice and WT (WT) mice were used. Th2 cell differentiation between VDR^-/- mice and WT mice was observed. We observed that CD4⁺ T cell activation was higher in VDR^-/- mice. The VDR^-/-CD4⁺ T cells were prone to Th2 polarization. VDR^-/- mice produced more immunoglobulin (Ig)E. VDR bound NLRP3 to prevent Th2 differentiation by restricting IL4 gene transcription. Th2 biased inflammation spontaneously developed in the intestine of VDR^-/- mice. In conclusion, VDR binds NLRP3 to restrict IL4 gene transcription and prevent biased Th2 polarization.

Thrombospondin-1 regulation of latent TGF-β activation: A therapeutic target for fibrotic disease

Transforming growth factor-β (TGF-β) is a central player in fibrotic disease. Clinical trials with global inhibitors of TGF-β have been disappointing, suggesting that a more targeted approach is warranted. Conversion of the latent precursor to the biologically active form of TGF-β represents a novel approach to selectively modulating TGF-β in disease, as mechanisms employed to activate latent TGF-β are typically cell, tissue, and/or disease specific. In this review, we will discuss the role of the matricellular protein, thrombospondin 1 (TSP-1), in regulation of latent TGF-β activation and the use of an antagonist of TSP-1 mediated TGF-β activation in a number of diverse fibrotic diseases. In particular, we will discuss the TSP-1/TGF-β pathway in fibrotic complications of diabetes, liver fibrosis, and in multiple myeloma. We will also discuss emerging evidence for a role for TSP-1 in arterial remodeling, biomechanical modulation of TGF-β activity, and in immune dysfunction. As TSP-1 expression is upregulated by factors induced in fibrotic disease, targeting the TSP-1/TGF-β pathway potentially represents a more selective approach to controlling TGF-β activity in disease.

Long-term effects: Galectin-1 and specific immunotherapy for allergic responses in the intestine

BACKGROUND AND AIMS

Mast cell activation interferes with the effects of allergen-specific immunotherapy (SIT). Galectin-1 (Gal-1) is capable of regulating immune cells' functions. This study tests the hypothesis that administration of Gal-1 promotes and prolongs the efficacy of SIT via suppressing mast cell activation.

METHODS

An intestinal allergy mouse model was developed. The coadministration of SIT and Gal-1 on suppression of the allergic responses, prevention of mast cell activation, and generation of antigen-specific regulatory T cells (Treg) in the intestine was observed in sensitized mice.

RESULTS

The coadministration of Gal-1 and SIT markedly suppressed the allergic responses in the mouse intestine vs the use of either SIT alone or Gal-1 alone. The Gal-1 binds to the IgE/FcɛRI complexes on the surface of mast cells to prevent mast cell activation during SIT. Gal-1 promoted the SIT-generated allergen-specific Tregs in the intestine of sensitized mice. Coadministration of Gal-1 and SIT significantly enhanced the efficacy of immunotherapy in suppressing allergic responses in the intestine, which lasted for at least for 12 months.

CONCLUSIONS

Long-term effects of specific immunotherapy on intestinal allergy can be achieved with Gal-1/SIT therapy by inhibiting mast cell activation and facilitating Treg development.

MicroRNA-98 interferes with thrombospondin 1 expression in peripheral B cells of patients with asthma

Thrombospondin 1 (TSP1)-producing B cells are an important immune regulatory cell fraction in the body, which are compromised in a number of immune diseases. miRs are involved in the immune regulation. The present study aims to elucidate the mechanism by which miR-98 interferes with the expression of TSP1 in B cells of the peripheral blood system. In the present study, peripheral blood samples were collected from patients with allergic asthma. The B cells were isolated from the blood samples to be analyzed for the expression of miR-98 and TSP1. The results showed that the levels of miR-98 were higher, the levels of TSP1 were lower, in B cells isolated from the peripheral blood in patients with asthma. A negative correlation was identified between the data of miR-98 and TSP1 in B cells. Exposure to T helper (Th) 2 (Th2) cytokine, interleukin (IL)-13, increased the expression of miR-98 and suppressed the expression of TSP1 in peripheral B cells, which was abolished by knocking down the miR-98 gene. In conclusion, miR-98 can suppress the expression of TSP1 in the peripheral B cells of patients with allergic asthma.

The Implications of DNA Methylation on Food Allergy

Food allergy is a major clinical and public health concern worldwide. The risk factors are well defined, however, the mechanisms by which they affect immune development remain largely unknown, and unfortunately the effective treatment or prevention of food allergy is still being researched. Recent studies show that the genes that are critical for the development of food allergy are regulated through DNA methylation. Environmental factors can affect host DNA methylation status and subsequently predispose people to food allergy. DNA methylation is therefore an important mediator of gene-environment interactions in food allergy and key to understanding the mechanisms underlying the allergic development. Indeed, the modification and identification of the methylation levels of specific genetic loci have gained increasing attention for therapeutic and diagnostic application in combating food allergy. In this review, we summarize and discuss the recent developments of DNA methylation in food allergy, including the pathogenesis, therapy, and diagnosis. This review will also summarize and discuss the environmental factors that affect DNA methylation levels in food allergy.

Micro RNA-155 plays a critical role in the initiation of food allergen-related inflammation in the intestine

The pathogenesis of food allergy (FA) is to be further investigated. Regulatory B cells (B10 cell) play a critical in the maintenance of the homeostasis in the intestine. Deregulation of B10 cell is associated with immune inflammation. Micro RNA (miR) 155 is involved in affecting immune cell function. This study tests a hypothesis that miR-155 affects the B10 cell function to facilitate the initiation of FA. In this study, BALB/c mice were sensitized to ovalbumin (OVA) to induce FA-like inflammation in the intestine. B cells were isolated from the intestine by magnetic cell sorting. The expression of miR-155 and IL-10 in B cells was assessed by real time RT-PCR. The results showed that mice sensitized to OVA showed FA-like inflammation and lower frequency of B10 cell in the intestine. B cells isolated from the intestine of FA mice showed higher levels of miR-155 and lower levels of IL-10. Although all the three T helper (Th)2 cytokines, including interleukin (IL)-4, IL-5 and IL-13, were higher in the serum, only IL-13 was positively correlated with the levels of miR-155 in the intestinal B cells. Exposure to IL-13 in the culture markedly increased the expression of miR-155 and suppressed the expression of IL-10 in B cells. Blocking miR-155 abolished the IL-13-induced IL-10 suppression in B cells and inhibited FA response in mice. In conclusion, miR-155 plays a critical role in the initiation of FA in mice. Blocking miR-155 has therapeutic potential in the treatment of FA.

Forkhead box protein-3 (Foxp3)-producing dendritic cells suppress allergic response

BACKGROUND

The generation of the tolerogenic dendritic cells (DC) is not fully understood yet. Forkhead box protein-3 (Foxp3) is an important molecule in the immune tolerance. This study tests a hypothesis that DCs express Foxp3, which can be upregulated by Staphylococcal enterotoxin B (SEB).

METHODS

The expression of Foxp3 by DCs was evaluated by real-time RT-PCR, Western blotting, flow cytometry, and chromatin immunoprecipitation assay.

RESULTS

We observed that mice treated with SEB at 0.25-0.5 μg/mouse showed high frequencies of transforming growth factor (TGF)-β-producing CD4⁺ T cells and TGF-β-producing DCs in the intestine, while the IL-4⁺ CD4⁺ T cells and TIM4⁺ DCs were dominated in the intestine in mice treated with SEB at 1-10 μg/mouse. Treating DCs with SEB in the culture induced high levels of Foxp3 at the TGF-β promoter locus. The function of Foxp3 was blocked by STAT6 (signal transducer and activator transcription-6); the latter was induced by exposing DCs to SEB in the culture at doses of 100-400 ng/ml. Treating allergic mice with specific immunotherapy (SIT) together with SEB significantly promoted the therapeutic effects on the allergic responses than treating with SIT alone.

CONCLUSION

Dendritic cells have the capacity to express Foxp3, which can be upregulated by exposure to SEB.

Innate and adaptive dendritic cell responses to immunotherapy

PURPOSE OF REVIEW

In allergic disease, dendritic cells play a critical role in orchestrating immune responses to innate stimuli and promoting the formation of T helper 2 (TH2) effector versus T-regulatory cells. Here, we review recent advances in our understanding of how current forms of immunotherapy modulate dendritic cell responses. (Figure is included in full-text article.)

RECENT FINDINGS

Sublingual immunotherapy (SLIT) and oral immunotherapy (OIT) for peanut allergy alter the expression of costimulatory molecules on dendritic cells, which leads to reduced expression of TH2 effector cytokines in an antigen-nonspecific manner. SLIT and OIT also modulate dendritic cell innate immune responses to Toll-like receptor agonists, including enhanced production of interferon α and reduced expression of proinflammatory cytokines that may serve to promote the development of tolerance. Dendritic cells isolated from patients post-OIT promoted hypomethylation of the FOXP3 locus in effector T cells. Reduced methylation of the FOXP3 locus has been associated with more persistent clinical desensitization following OIT. Recent studies have additionally highlighted a role for B cells in inducing tolerogenic dendritic cell populations and T-regulatory cells during immunotherapy. Epicutaneous immunotherapy may also elicit immunosuppressive populations of cutaneous dendritic cells, although in some cases, antigen exposure through the skin can lead to sensitization. Finally, efforts have focused on identifying pharmacologic and/or antigen-independent strategies of altering dendritic cell function to enhance the immunosuppressive effects of immunotherapy.

SUMMARY

Dendritic cells are a critical target of immunotherapy. Alterations in both adaptive and innate immunity likely underlie the immunosuppressive effects of this treatment.

Secondary allergic T cell responses are regulated by dendritic cell-derived thrombospondin-1 in the setting of allergic eye disease

Allergic eye disease, as in most forms of atopy, ranges in severity among individuals from immediate hypersensitivity to a severe and debilitating chronic disease. Dendritic cells play a key role in stimulating pathogenic T cells in allergen re-exposure, or secondary responses. However, molecular cues by dendritic cells underpinning allergic T cell response levels and the impact that this control has on consequent severity of allergic disease are poorly understood. Here, we show that a deficiency in thrombospondin-1, a matricellular protein known to affect immune function, has subsequent effects on downstream T cell responses during allergy, as revealed in an established mouse model of allergic eye disease. More specifically, we demonstrate that a thrombospondin-1 deficiency specific to dendritic cells leads to heightened secondary T cell responses and consequent clinical disease. Interestingly, whereas thrombospondin-1-deficient dendritic cells augmented activity of allergen-primed T cells, this increase was not recapitulated with naïve T cells in vitro. The role of dendritic cell-derived thrombospondin-1 in regulating secondary allergic T cell responses was confirmed in vivo, as local transfer of thrombospondin-1-sufficient dendritic cells to the ocular mucosa of thrombospondin-1 null hosts prevented the development of augmented secondary T cell responses and heightened allergic eye disease clinical responses. Finally, we demonstrate that topical instillation of thrombospondin-1-derived peptide reduces T cell activity and clinical progression of allergic eye disease. Taken together, this study reveals an important modulatory role of dendritic cell-derived thrombospondin-1 on secondary allergic T cell responses and suggests the possible dysregulation of dendritic cell-derived thrombospondin-1 expression as a factor in allergic eye disease severity.

Micro RNA-17-92 cluster mediates interleukin-4-suppressed IL-10 expression in B cells

The pathogenesis of allergen-related inflammation in the intestine is to be further understood. Micro RNA (miR) can regulate immune responses. This study aims to investigate the role of miR-17-92 cluster in the induction of food allergen-related inflammation in the intestine. In this study, a mouse model of food allergen-related intestinal inflammation was developed. Expression of miR-17-92 cluster in B cells of the intestinal mucosa was analyzed by real time quantitative RT-PCR. The results showed that the levels of miR-19a, one of the members of the miR-17-92 cluster, were detected in the B cells of the intestine of mice sensitized to ovalbumin, which was significantly higher than that in naïve control mice. The expression of IL-10 by B cells was significantly lower in the sensitized mice as compared with naive control mice. Exposure to IL-4 in the culture increased the expression of miR-19a as well as suppression the expression of IL-10 in B cells via remolding DNA structure at the IL-10 promoter locus. We conclude that B cells from sensitized mice show higher levels of miR-19a, which plays an important role in the suppression of IL-10 in the B cells.