Exposure of ovalbumin during pregnancy prevents the development of allergic rhinitis in offspring through the induction of mast cell autophagy

Most allergic disease studies have focused on postnatal chemical or microbial exposure. Recent studies have indicated that allergic diseases are associated with the immunological interaction between the mother and her offspring, but the relevant mechanisms are unclear. The aim of this study was to assess whether maternal exposure to allergens during pregnancy could affect allergic rhinitis (AR) in the offspring. Compared with offspring of naïve mothers, offspring of ovalbumin (OVA)-exposed mothers exhibited a significant reduction in AR clinical symptoms and levels of histamine, IgE, T helper type-2(Th2) cytokines, thymic stromal lymphopoietin, cyclooxygenase-2, chemokines, infiltration of inflammatory cell, and activity of caspase-1. Interestingly, we observed that offspring of OVA-exposed mothers regulated OVA-induced Th2 responses by inducing autophagy in mast cells. Our data demonstrated that maternal exposure to OVA during pregnancy decreased allergic sensitivity in offspring, suggesting that the vertical transmission of maternal immune responses may be involved. These findings have important implications in the regulation of AR. Furthermore, we propose that the autophagy of mast cells may be a potential target for AR prevention or treatment.

Mechanisms of sex hormones in autoimmunity: focus on EAE

Sex-related differences in the occurrence of autoimmune diseases is well documented, with females showing a greater propensity to develop these diseases than their male counterparts. Sex hormones, namely dihydrotestosterone and estrogens, have been shown to ameliorate the severity of inflammatory diseases. Immunologically, the beneficial effects of sex hormones have been ascribed to the suppression of effector lymphocyte responses accompanied by immune deviation from pro-inflammatory to anti-inflammatory cytokine production. In this review, we present our view of the mechanisms of sex hormones that contribute to their ability to suppress autoimmune responses with an emphasis on the pathogenesis of experimental autoimmune encephalomyelitis.

Anaphylaxis caused by repetitive doses of a GITR agonist monoclonal antibody in mice

Immunotherapy for cancer using antibodies to enhance T-cell function has been successful in recent clinical trials. Many molecules that improve activation and effector function of T cells have been investigated as potential new targets for immunomodulatory antibodies, including the tumor necrosis factor receptor superfamily members GITR and OX40. Antibodies engaging GITR or OX40 result in significant tumor protection in preclinical models. In this study, we observed that the GITR agonist antibody DTA-1 causes anaphylaxis in mice upon repeated intraperitoneal dosing. DTA-1-induced anaphylaxis requires GITR, CD4(+) T cells, B cells, and interleukin-4. Transfer of serum antibodies from DTA-1-treated mice, which contain high levels of DTA-1-specific immunoglobulin G1 (IgG1), can induce anaphylaxis in naive mice upon administration of an additional dose of DTA-1, suggesting that anaphylaxis results from anti-DTA-1 antibodies. Depletion of basophils and blockade of platelet-activating factor, the key components of the IgG1 pathway of anaphylaxis, rescues the mice from DTA-1-induced anaphylaxis. These results demonstrate a previously undescribed lethal side effect of repetitive doses of an agonist immunomodulatory antibody as well as insight into the mechanism of toxicity, which may offer a means of preventing adverse effects in future clinical trials using anti-GITR or other agonist antibodies as immunotherapies.

Allergen-specific responses of CD19(+)CD5(+)Foxp3(+) regulatory B cells (Bregs) and CD4(+)Foxp3(+) regulatory T cell (Tregs) in immune tolerance of cow milk allergy of late eczematous reactions

Foxp3-expressing cells among CD19(+)CD5(+) B cells were identified as regulatory B cells. Food allergy manifesting as late eczematous reactions is regarded as a non-IgE-mediated food allergy. The diagnosis for milk allergy manifesting as late eczematous reactions was made on the basis of the findings obtained from a double-blind placebo-controlled food challenge in patients with atopic dermatitis. Twelve patients with milk allergy and 12 patients who could tolerate milk were selected. On casein stimulation, the CD19(+)CD5(+)Foxp3(+) B cell (Breg) fraction in CD5(+) B cells decreased from 4.4±1.1% to 3.1±0.7% (P=0.047, n=12) in the milk allergy group and increased from 4.4±1.3% to 5.2±1.4% (P=0.001, n=10) in the milk-tolerant group. On the other hand, on allergen stimulation, the number of CD4(+)Foxp3(+) regulatory T cells (Tregs) in the milk allergy group and milk-tolerant group increased from 2.6±0.7% to 3.4±0.6% (P=0.014, n=9) and from 2.7±1.0% to 3.5±1.0% (P=0.038, n=10), respectively. In conclusion, allergen-specific responses of Bregs, rather than those of Tregs, seem to influence the immune responses (i.e., allergy or tolerance) to a food allergen.

T regulatory cells participate in the control of germinal centre reactions

Germinal centre (GC) reactions are central features of T-cell-driven B-cell responses, and the site where antibody-producing cells and memory B cells are generated. Within GCs, a range of complex cellular and molecular events occur which are critical for the generation of high affinity antibodies. These processes require exquisite regulation not only to ensure the production of desired antibodies, but to minimize unwanted autoreactive or low affinity antibodies. To assess whether T regulatory (Treg) cells participate in the control of GC responses, immunized mice were treated with an anti-glucocorticoid-induced tumour necrosis factor receptor-related protein (GITR) monoclonal antibody (mAb) to disrupt Treg-cell activity. In anti-GITR-treated mice, the GC B-cell pool was significantly larger compared with control-treated animals, with switched GC B cells composing an abnormally high proportion of the response. Dysregulated GCs were also observed regardless of strain, T helper type 1 or 2 polarizing antigens, and were also seen after anti-CD25 mAb treatment. Within the spleens of immunized mice, CXCR5(+) and CCR7(-) Treg cells were documented by flow cytometry and Foxp3(+) cells were found within GCs using immunohistology. Final studies demonstrated administration of either anti-transforming growth factor-β or anti-interleukin-10 receptor blocking mAb to likewise result in dysregulated GCs, suggesting that generation of inducible Treg cells is important in controlling the GC response. Taken together, these findings indicate that Treg cells contribute to the overall size and quality of the humoral response by controlling homeostasis within GCs.

Histamine regulates autoreactive T cell activation and adhesiveness in inflamed brain microcirculation

Histamine may contribute to the pathology of MS and its animal model EAE. We explored the effects of histamine and specific HR agonists on activation and migratory capacity of myelin-autoreactive T cells. We show that histamine in vitro inhibits proliferation and IFN-γ production of mouse T cells activated against PLP(139-151). These effects were mimicked by the H1R agonist HTMT and the H2R agonist dimaprit and were associated with reduced activation of ERK½ kinase and with increased levels of cell cycle inhibitor p27Kip-1, both involved in T cell proliferation and anergy. H1R and H2R agonists reduced spontaneous and chemokine-induced adhesion of autoreactive T cells to ICAM-1 in vitro and blocked firm adhesion of these cells in inflamed brain microcirculation in vivo. Thus histamine, through H1R and H2R, inhibits activation of myelin-autoreactive T cells and their ability to traffic through the inflamed BBB. Strategies aimed at interfering with the histamine axis might have relevance in the therapy of autoimmune disease of the CNS.

Exploring a regulatory role for mast cells: 'MCregs'?

Regulatory cells can mould the fate of the immune response by direct suppression of specific subsets of effector cells, or by redirecting effectors against invading pathogens and infected or neoplastic cells. These functions have been classically, although not exclusively, ascribed to different subsets of T cells. Recently, mast cells have been shown to regulate physiological and pathological immune responses, and thus to act at the interface between innate and adaptive immunity assuming different functions and behaviors at discrete stages of the immune response. Here, we focus on these poorly defined, and sometimes apparently conflicting, functions of mast cells.

Allergy and multiple sclerosis: a population-based case-control study

BACKGROUND

Epidemiological studies on the association between allergic disorders, T-helper type 2 (Th2) mediated, and multiple sclerosis (MS), a T-helper type 1 (Th1)/Th17-mediated disease, provided conflicting results.

OBJECTIVE

The aim of this study was to further examine the association between allergic disorders and MS.

METHODS

The association between MS and previous medical history of any type of allergy has been investigated in a population-based case-control study conducted in Northern Italy, based on telephone interviews to 423 cases and 643 population controls (refusal rates 3.7% and 9.4%, respectively). Controls were a random sample of the general population.

RESULTS

A history of atopic allergies seems to confer protection against MS (odds ratio [OR], 0.58; 95% confidence interval [CI], 0.38-0.89; P = 0.012). In particular, the prevalence of allergic asthma was 4.9% in people with MS and 12% in control subjects (OR = 0.38; 95% CI 0.22-0.66, P < 0.01). No association was found between MS and nonatopic allergies.

CONCLUSIONS

Our findings are confirmatory of the putative protective effect of Th2-mediated disorders on Th1 immune responses associated with MS. A unifying theory on the mechanisms by which previous history of atopic allergies may modify the risk of MS is still lacking.

Elevated serum cytokines during human anaphylaxis: Identification of potential mediators of acute allergic reactions

BACKGROUND

Anaphylaxis is generally unanticipated and requires emergency management. Therefore, the biological mediators in human beings have been difficult to define.

OBJECTIVE

Our aim was to identify cytokines and chemokines whose concentrations increase during anaphylaxis in human beings and to determine how each correlates with severity.

METHODS

We measured the concentrations of potential mediators, including cytokines, chemokines, mast cell tryptase (MCT), and histamine, over 3 time points in 76 patients presenting to emergency departments with anaphylaxis and correlated these with a global severity scale, hypotension, and hypoxia.

RESULTS

IL-2, IL-6, IL-10, TNF receptor I, MCT, and histamine were significantly elevated in patients with severe reactions (n = 36) compared with moderate reactions (n = 40) and healthy controls. Histamine levels peaked at emergency department arrival, whereas other mediators peaked later. IL-4, IL-5, IL-13, IFN-gamma, and TNF-alpha were marginally elevated in severe reactions compared with healthy controls but did not correlate with reaction severity. Severe reactions tended to be either hypotensive (n = 19) or hypoxemic (n = 12). Levels of IL-6, IL-10, TNF receptor I, MCT, and histamine correlated with hypotension. No mediator correlated with hypoxemia or other respiratory features.

CONCLUSION

This study confirms that the concentrations of a number of cytokines are elevated in blood during anaphylaxis in human beings and that some correlate with the presence of hypotension. Others were only marginally elevated within a concentration range that available assays do not reliably detect. During respiratory reactions, mediators may be largely confined to the airways so that blood concentrations do not reflect activity.

Anaphylaxis to a self-peptide in the absence of mast cells or histamine

Induction of T helper 1 (Th1) to Th2 deviation through administration of self- or altered self-peptides holds promise for treatment of autoimmunity. However, administration of self-peptides in models of autoimmunity can result in anaphylactic reactions. Although both IgE and IgG1 antibodies might be involved in the development of anaphylaxis to myelin peptides in experimental autoimmune encephalomyelitis in mice, the effector cells and molecules involved are not fully understood. Here we show that systemic anaphylaxis to the self-antigen myelin oligodendrocyte glycoprotein (MOG) 35-55 can occur in mice lacking mast cells (Kit(W)/Kit(W-v) mice) or histamine (histidine decarboxylase-deficient mice), but is prevented in mice lacking IL-4. Treatment of mice with CV6209, a platelet-activating factor antagonist, slightly reduced the incidence of anaphylaxis to self-MOG35-55 in this model, but more effectively protected mice against anaphylaxis to this peptide when self-MOG35-55 was administered in a different immunization protocol that omitted the use of Bordetella pertussis toxin as an adjuvant at the time of immunization. Thus, anaphylactic reactions to self-MOG can occur in the absence of mast cells or histamine, key elements of the classical IgE-, mast cell-, and histamine-dependent pathway of anaphylaxis.