SLIT improves cedar pollinosis by restoring IL-10 production from Tr1 and Monocytes∼IL-10 productivity is critical for becoming allergic∼

Allergen immunotherapy in asthma

Allergen immunotherapy (AIT), including SCIT and SLIT, is a treatment that involves the administration of allergens to which patients with allergic diseases have been sensitized. HDM-SCIT for asthma is indicated in cases of HDM-sensitized allergic asthma with normal lung function. HDM-SCIT improves asthma symptoms and AHR, and decreases the medication dose. Importantly, AIT can improve other allergic diseases complicated by asthma, such as allergic rhinitis, which can also contribute to the improvement of asthma symptoms. Several studies have suggested that HDM-SLIT also attenuates the risk of asthma exacerbations, and improves lung function in asthma cases with allergic rhinitis. Furthermore, AIT can modify the natural course of allergic diseases, including asthma. For example, the effects of AIT are maintained for at least several years after treatment discontinuation. AIT can prevent the onset of asthma when introduced in allergic rhinitis, and can also inhibit or reduce new allergen sensitizations. Recent data have suggested that AIT may suppress non-targeted allergen-induced immune responses in addition to targeted allergen-induced responses, and suppress infections of the lower respiratory tract by enhancing IFN responses.

Potential Effects of AIT on Nonspecific Allergic Immune Responses or Symptoms

Allergen immunotherapy (AIT) is a treatment in which clinically corresponding allergens are administered to patients with allergic diseases, either by subcutaneous immunotherapy (SCIT) or sublingual immunotherapy (SLIT), or by oral immunotherapy (OIT) in the case of food allergy. Since etiological allergens are administered to patients, AIT is presumed to modify mainly allergen-specific immune responses. In bronchial asthma, AIT with house dust mites (HDM) alleviates clinical symptoms, suppresses airway hyperresponsiveness, and reduces medication doses of HDM-sensitive asthmatics. Moreover, AIT can suppress the symptoms of other allergic diseases associated with asthma including allergic rhinitis. However, AIT sometimes reduces allergic symptoms not induced by the responsible allergens, such as non-targeted allergens, in clinical settings. Furthermore, AIT can suppress the spread of sensitization to new allergens that are not targeted allergens by AIT, suggesting the suppression of allergic immune responses in an allergen-nonspecific manner. In this review, the nonspecific suppression of allergic immune responses by AIT is discussed. AIT has been reported to increase regulatory T cells that produce IL-10, transforming growth factor-β, and IL-35, IL-10-producing regulatory B cells, and IL-10-producing innate lymphoid cells. These cells can suppress type-2 mediated immune responses mainly through the production of anti-inflammatory cytokines or a cell-cell contact mechanism, which may be involved in the nonspecific suppression of allergic immune responses by AIT.

Roles of type 1 regulatory T (Tr1) cells in allergen-specific immunotherapy

Allergen-specific immunotherapy (AIT) is the only causative treatment for allergic diseases by modification of the immune response to allergens. A key feature of AIT is to induce immunotolerance to allergens by generating antigen-specific regulatory T (Treg) cells in allergic patients. Type 1 regulatory T (Tr1) cells and forkhead box protein 3 (Foxp3)-expressing Treg cells are well known among Treg cell subsets. Foxp3 was identified as a master transcription factor of Treg cells, and its expression is necessary for their suppressive activity. In contrast to Foxp3⁺ Treg cells, the master transcription factor of Tr1 cells has not been elucidated. Nevertheless, Tr1 cells are generally considered as a distinct subset of Treg cells induced in the periphery during antigen exposure in tolerogenic conditions and can produce large amounts of anti-inflammatory cytokines such as interleukin-10 and transforming growth factor-β, followed by down-regulation of the function of effector immune cells independently of Foxp3 expression. Since the discovery of Tr1 cells more than 20 years ago, research on Tr1 cells has expanded our understanding of the mechanism of AIT. Although the direct precursors and true identity of these cells continues to be disputed, we and others have demonstrated that Tr1 cells are induced in the periphery by AIT, and the induced cells are re-activated by antigens, followed by suppression of allergic symptoms. In this review, we discuss the immune mechanisms for the induction of Tr1 cells by AIT and the immune-suppressive roles of Tr1 cells in AIT.

Regulatory T and B cells in peripheral blood of subcutaneous immunotherapy-treated Japanese cedar pollinosis patients

AIM

The aim of this study was to clarify whether there are more regulatory T (Treg) and regulatory B (Breg) cells, and higher levels of IL-10-related transcription factors in subcutaneous immunotherapy (SCIT)-treated pollinosis patients than in non-SCIT-treated patients.

METHODS

Japanese cedar pollinosis patients undergoing SCIT had received treatment for at least 2.8 years. Peripheral blood mononuclear cells were used for flow cytometer analyses and mRNA measurement.

RESULTS

The numbers of type 1 regulatory T (Tr1)-like cells and Breg cells, and expression of E4BP4 mRNA by peripheral blood mononuclear cells in SCIT-treated patients were higher than those in non-SCIT-treated patients.

CONCLUSION

Tr1-like cells, Breg cells and E4BP4 may be involved in the effectiveness of SCIT.

Immunological effects of sublingual immunotherapy with Japanese cedar pollen extract in patients with combined Japanese cedar and Japanese cypress pollinosis

Sublingual immunotherapy (SLIT) with Japanese cedar (JCe) pollinosis was expected to be effective for Japanese cypress (JCy) pollinosis. However, only a half of JCy pollinosis patients clinically improved. Therefore, we examined the immunological effect of SLIT for JCy pollinosis. Peripheral blood mononuclear cells (PBMCs) from patients with JCe and JCy pollinosis who did and did not receive SLIT were incubated with Cry j 1, Cha o 1 and Cha o 3 antigens. Basophil activation test (BAT) were performed. Production of IL-5 and IL-17 induced by antigens was inhibited in the SLIT group. Cry j 1-specific production of IL-10 was increased, and serum Cry j 1-specific IgE and -IgG4 were elevated. However, Cha o 1- or Cha o 3-specific production of IL-10 and specific IgG4 was not increased. Antigens-specific BAT did not decrease after SLIT. New SLIT with JCe and JCy is needed for patients with combined JCe and JCy pollinosis.

The impact of allergen exposure and specific immunotherapy on circulating blood cells in allergic rhinitis

Allergic rhinitis (AR) is an IgE-mediated inflammatory disease of the nasal mucosa with well described local immune responses during allergen exposure. The frequent association of AR with general extra-nasal symptoms and other allergic conditions, such as conjunctivitis and asthma, however, support a more systemic disease impact. In addition to acute elevation of soluble inflammatory mediators in periphery blood, a growing number of studies have reported changes in circulating blood cells after specific nasal allergen challenge or environmental allergen exposure. These findings imply an involvement of specific blood leukocyte subsets, thrombocytes and recently, erythrocytes. This review summarizes the circulating blood cell dynamics associated with allergen exposure in AR subjects reported so far. Additionally, the impact of therapy, particularly allergen-specific immunotherapy (AIT), the only currently available causal treatment reducing AR-related symptoms, is further considered in this context.

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.

Next generation immunotherapy for tree pollen allergies

Tree pollen induced allergies are one of the major medical and public health burdens in the industrialized world. Allergen-Specific Immunotherapy (AIT) through subcutaneous injection or sublingual delivery is the only approved therapy with curative potential to pollen induced allergies. AIT often is associated with severe side effects and requires long-term treatment. Safer, more effective and convenient allergen specific immunotherapies remain an unmet need. In this review article, we discuss the current progress in applying protein and peptide-based approaches and DNA vaccines to the clinical challenges posed by tree pollen allergies through the lens of preclinical animal models and clinical trials, with an emphasis on the birch and Japanese red cedar pollen induced allergies.

FoxP3 Tregs Response to Sublingual Allergen Specific Immunotherapy in Children Depends on the Manifestation of Allergy

Over the last decades allergic diseases has become a major health problem worldwide. The only specific treatment to date is allergen specific immunotherapy (ASIT). Although it was shown that ASIT generates allergen-tolerant T cells, detailed mechanism underlying its activity is still unclear and there is no reliable method to monitor its effectiveness. The aim of our study was to evaluate ASIT influence on the frequency of forkhead box P3 (FoxP3) Tregs in allergic children with various clinical manifestations. The relative number of FoxP3 Tregs in 32 blood samples from allergic children at baseline and/or after 1 year of ASIT was assessed by flow cytometry. In the entire studied group, the percentage of FoxP3 Tregs did not increase 1 year after ASIT. Nevertheless, the percentage of FoxP3 Tregs after ASIT significantly increased in children with respiratory allergy (conjunctivitis, asthma, and rhinitis) coexisting with nonrespiratory manifestations (food allergy and/or atopic dermatitis), whereas, in patients with respiratory allergy only, the percentage of FoxP3 Tregs decreased. To the best of our knowledge, this is the first report showing various differential FoxP3 Tregs response to ASIT in allergic children. FoxP3 Tregs number could be useful in treatment monitoring. Further studies are warranted to confirm these observations.

Immunological parameters in prophylactic sublingual immunotherapy in asymptomatic subjects sensitized to Japanese cedar pollen

BACKGROUND

This study aims to examine the immunological parameters, focusing IL-10 productivity, in prophylactic sublingual immunotherapy (SLIT) in asymptomatic subjects sensitized to Japanese cedar pollen (JCP).

METHODS

This study was conducted as part of a randomized, double-blind, placebo-controlled, multiple center trial, and was performed for two consecutive pollen seasons in 2012 and 2013. The present results were based only on our institution. We recruited 29 participants with specific IgE against JCP of at class 2 and higher levels without history of the pollinosis symptoms at the time of JCP scattering. The SLIT group received standardized JCP extract for five months over the pollen season. We observed and judged development of the symptoms in the pollen season. The percentage of IL-10 producing CD4(+) T (Trl) cells, B cells and monocytes were analyzed by flow cytometry. JCP specific IgE and total IgE were also measured.

RESULTS

The ratio of development of cedar pollinosis was significantly lower in the SLIT group compared to the placebo group in 2013. In 2012, the percentage of circulating Tr1 cells and IL-10 producing monocytes significantly increased in the SLIT group. In 2013, the percentage of circulating Tr1 cells and IL-10 producing B cells increased significantly in the SLIT group. The percentage of circulating IL-10 producing monocytes significantly decreased in the placebo group.

CONCLUSIONS

Prophylactic SLIT is effective for prevention of the development of pollinosis. Induction of IL-10 producing T cells, B cells and monocytes is an important mechanism of SLIT for prevention of pollinosis in asymptomatic but sensitized subjects.

Repeated antigen painting and sublingual immunotherapy in mice convert sublingual dendritic cell subsets

The sublingual mucosa (SLM) is utilized as the site for sublingual immunotherapy (SLIT) to induce tolerance against allergens. The contribution of SLM-dendritic cells (SLM-DCs) has not been clarified. The aim of this study was to examine the dynamics and phenotype of SLM-DCs after topical antigen painting and SLIT. SLM-DCs were histologically evaluated after FITC painting. A novel murine Japanese cedar pollinosis (JCP) model was generated and change in SLM-DCs after SLIT was examined. The density of SLM-DCs was clearly lower compared with the buccal mucosa and dorsal surface of the tongue. Topical FITC painting on the SLM induced maximal recruitment of submucosal DCs (smDCs) at 6h, but most smDCs had vanished at 24h. Repeated painting on the SLM induced exhaustion and conversion of the smDC phenotype. CD206(high)CD11c(low) round-type cells with fewer dendrites and less lymph node migration capacity became dominant. In the murine model of JCP, SLIT efficiently inhibited clinical symptoms and allergen-mediated immunological responses. SLIT markedly reduced the number of SLM-DCs, converted to the round-type dominant phenotype and inhibited the activation of regional lymph node DCs. Topical antigen painting on the SLM induced rapid exhaustion and conversion of smDCs. The unique dynamics of SLM-DCs may contribute to tolerance induction in SLIT.

Continuous high-dose antigen exposure preferentially induces IL-10, but intermittent antigen exposure induces IL-4

IL-10 plays a critical role in the induction of specific T-cell tolerance. To date, whether IL-10 induction by antigen application is dose- or time-dependent remains unclear. In this study, IL-10 induction by allergen exposure was investigated in the several schedules. Oxazolone was repeatedly applied to mouse ear, and mRNA of inflammatory cytokines in lesional skins was measured. The results indicated that continuous high-dose antigen exposure induces IL-4 as well as abundant IL-10 production. Monocytes/dendritic cells and T cells are major source of IL-10. Allergen-specific immunotherapy is resumed before antigen scattering: preseason. We evaluated safe-loading dose of allergens in preseasonal therapy focusing Tr1 induction. Restarting immunotherapy with high dose effectively augmented IL-10 expression accompanied with further induction of IL-4 and inflammatory cytokines. Therefore, the protocol restarting with low-dose antigen is preferential to obviate the risk of exacerbation or anaphylaxis.

Birch pollen immunotherapy results in long-term loss of Bet v 1-specific TH2 responses, transient TR1 activation, and synthesis of IgE-blocking antibodies

BACKGROUND

Early events of specific immunotherapy (SIT) are induction of allergen-specific IL-10-producing T(R)1 cells and production of IgG antibodies, but there is little knowledge about the long-term immune mechanisms responsible for sustained allergen tolerance.

OBJECTIVE

Bet v 1-specific immune responses of 16 patients with birch pollen allergy were characterized up to 54 months at defined time points before, during, and after a 3-year period of SIT.

METHODS

We sought to analyze allergen-specific T- and B-cell responses. Bet v 1-specific IL-5-, IFN-γ-, and IL-10-secreting T cells were quantified in peripheral blood, and birch pollen-specific IgE and IgG antibody levels were determined in serum. Furthermore, the inhibitory capacity of SIT-induced IgG was evaluated by blocking allergen binding to IgE and inhibition of facilitated allergen presentation.

RESULTS

Seasonal increases in Bet v 1-specific T(H)2 cell numbers ceased to appear after the first year of SIT without deviation to a T(H)1-dominated immune response. Furthermore, the frequency of IL-10-producing T(R)1 cells, which had increased during the first year of SIT, returned to pretreatment levels in the second year. In contrast, allergen-specific IgG antibody concentrations continuously increased during SIT but started to decrease after cessation of treatment. Functional analysis confirmed the ability of the IgG antibodies to inhibit IgE-allergen interactions, which peaked at the end of SIT but then slowly started to decrease.

CONCLUSION

Long-term allergen tolerance achieved by SIT is associated with the development of peripheral T-cell tolerance characterized by decreased reactivity of Bet v 1-specific T(H)2 cells and enriched allergen-specific IgG competing with IgE antibodies for allergen binding.