T regulatory cells and the control of allergic disease

Modulation of the Immune System Mechanisms using Probiotic Bacteria in Allergic Diseases: Focus on Allergic Retinitis and Food Allergies

Allergic illnesses occur when an organism's immune system is excessively responsive to certain antigens, such as those that are presented in the environment. Some people suffer from a wide range of immune system-related illnesses including allergic rhinitis, asthma, food allergies, hay fever, and even anaphylaxis. Immunotherapy and medications are frequently used to treat allergic disorders. The use of probiotics in bacteriotherapy has lately gained interest. Probiotics are essential to human health by modulating the gut microbiota in some ways. Due to probiotics' immunomodulatory properties present in the gut microbiota of all animals, including humans, these bacterial strains can prevent a wide variety of allergic disorders. Probiotic treatment helps allergy patients by decreasing inflammatory cytokines and enhancing intestinal permeability, which is important in the battle against allergy. By altering the balance of Th1 and Th2 immune responses in the intestinal mucosa, probiotics can heal allergic disorders. Numerous studies have shown a correlation between probiotics and a reduced risk of allergy disorders. A wide range of allergic disorders, including atopic dermatitis, asthma, allergic retinitis and food allergies has been proven to benefit from probiotic bacteria. Therefore, the use of probiotics in the treatment of allergic diseases offers a promising perspective. Considering that probiotic intervention in the treatment of diseases is a relatively new field of study, more studies in this regard seem necessary.

Exposure to Deoxynivalenol During Pregnancy and Lactation Enhances Food Allergy and Reduces Vaccine Responsiveness in the Offspring in a Mouse Model

Deoxynivalenol (DON), a highly prevalent contaminant of grain-based products, is known to induce reproductive- and immunotoxicities. Considering the importance of immune development in early life, the present study investigated the effects of perinatal DON exposure on allergy development and vaccine responsiveness in the offspring. Pregnant mice received control or DON-contaminated diets (12.5 mg/kg diet) during pregnancy and lactation. After weaning, female offspring were sensitized to ovalbumin (OVA) by oral administration of OVA with cholera toxin (CT). Male offspring were injected with Influvac vaccine. OVA-specific acute allergic skin response (ASR) in females and vaccine-specific delayed-type hypersensitivity (DTH) in males were measured upon intradermal antigen challenge. Immune cell populations in spleen and antigen-specific plasma immunoglobulins were analyzed. In female CT+OVA-sensitized offspring of DON-exposed mothers ASR and OVA-specific plasma immunoglobulins were significantly higher, compared to the female offspring of control mothers. In vaccinated male offspring of DON-exposed mothers DTH and vaccine-specific antibody levels were significantly lower, compared to the male offspring of control mothers. In both models a significant reduction in regulatory T cells, Tbet+ Th1 cells and Th1-related cytokine production of the offspring of DON-exposed mothers was observed. In conclusion, early life dietary exposure to DON can adversely influence immune development in the offspring. Consequently, the immune system of the offspring may be skewed towards an imbalanced state, resulting in an increased allergic immune response to food allergens and a decreased immune response to vaccination against influenza virus in these models.

Anti-Tumor Necrosis Factor Receptor 2 Antibody Combined With Anti-PD-L1 Therapy Exerts Robust Antitumor Effects in Breast Cancer

Breast cancer is a leading type of malignant tumor in women; however, the immunotherapy in breast cancer is still underappreciated. In this study, we demonstrated that tumor necrosis factor receptor 2 (TNFR2) is highly expressed in both breast tumor tissue and tumor-infiltrating immunosuppressive CD4⁺Foxp3⁺ regulatory T cells (Tregs). We found that TNFR2 antagonistic antibody reduced Foxp3 expression and the proliferation of Tregs and impaired the inhibitory effect of Tregs on CD4⁺CD25^– effector T (Teff) cells in a dose-dependent manner. The treatment of anti-TNFR2 antibody not only inhibited the proliferation of breast tumor cells in vitro but also suppressed the tumorigenesis of murine mammary carcinoma 4T1 cells in vivo. Mice recovered from tumor growth also developed 4T1-specific immunity. Furthermore, we demonstrated that anti-TNFR2 antibody in combination with anti-PD-L1 exhibited augmented antitumor effects than monotherapy. Anti-TNFR2 treatment also tended to increase the expression of proinflammatory cytokines in tumor tissues. In conclusion, our study suggests that TNFR2 antagonist could potentially offer a clinical benefit as a single agent or in combination with immune checkpoint blockade treatment for breast cancer immunotherapy.

Role of CD4+CD25+FOXP3+ TReg cells on tumor immunity

Not all T cells are effector cells of the anti-tumor immune system. One of the subpopulations of CD4⁺ T cells that express CD25⁺ and the transcription factor FOXP3, known as Regulator T cells (T_Reg), plays an essential role in maintaining tolerance and immune homeostasis preventing autoimmune diseases, minimalize chronic inflammatory diseases by enlisting various immunoregulatory mechanisms. The balance between effector T cells (T_eff) and regulator T cells is crucial in determining the outcome of an immune response. Regarding tumors, activation or expansion of T_Reg cells reduces anti-tumor immunity. T_Reg cells inhibit the activation of CD4⁺ and CD8⁺ T cells and suppress anti-tumor activity in the tumor microenvironment. In addition, T_Reg cells also promote tumor angiogenesis both directly and indirectly to ensure oxygen and nutrient transport to the tumor. There is accumulating evidence showing a positive result that removing or suppressing T_Reg cells increases anti-tumor immune response. However, depletion of T_Reg cells will cause autoimmunity. One strategy to improve or restore tumor immunity is targeted therapy on the dominant effector T_Reg cells in tumor tissue. Various molecules such as CTLA-4, CD4, CD25, GITR, PD-1, OX40, ICOS are in clinical trials to assess their role in attenuating T_Reg cells' function.

Regulatory roles of MicroRNA in shaping T cell function, differentiation and polarization

T lymphocytes are an integral component of adaptive immunity with pleotropic effector functions. Impairment of T cell activity is implicated in various immune pathologies including autoimmune diseases, AIDS, carcinogenesis, and periodontitis. Evidently, T cell differentiation and function are under robust regulation by various endogenous factors that orchestrate underlying molecular pathways. MicroRNAs (miRNA) are a class of noncoding, regulatory RNAs that post-transcriptionally control multiple mRNA targets by sequence-specific interaction. In this article, we will review the recent progress in our understanding of miRNA-gene networks that are uniquely required by specific T cell effector functions and provide miRNA-mediated mechanisms that govern the fate of T cells. A subset of miRNAs may act in a synergistic or antagonistic manner to exert functional suppression of genes and regulate pathways that control T cell activation and differentiation. Significance of T cell-specific miRNAs and their dysregulation in immune-mediated diseases is discussed. Exosome-mediated horizontal transfer of miRNAs from antigen presenting cells (APCs) to T cells and from one T cell to another T cell subset and their impact on recipient cell functions is summarized.

Efficacy and action mechanisms of a Chinese herbal formula on experimental models of atopic dermatitis

ETHNOPHARMACOLOGICAL RELEVANCE

Atopic dermatitis (AD) is a skin inflammatory disease characterized by erythema, eruption, lichenification and pruritus. Shi Zhen Formula (SZF), an empirical Chinese herbal preparation, has clinical efficacy in relieving the symptoms of AD patients. However, the underlying molecular mechanisms of SZF remained unclear.

AIM OF THE STUDY

We aimed to investigate the anti-AD effects of SZF and elucidate its underlying molecular mechanisms using in vitro and in vivo models of AD.

MATERIALS AND METHODS

High-performance liquid chromatography analysis was performed for quality control of SZF extract. The anti-inflammatory effect of SZF was investigated through evaluating the levels of nitric oxide (NO), chemokines and pro-inflammatory cytokines in the lipopolysaccharide (LPS) stimulated RAW264.7 cells. AD-like skin lesions in female BALB/c mice were induced by 2,4-dinitrochlorobenzene (DNCB). SZF (3.15, 6.30 and 9.45 g/kg) and dexamethasone (5 mg/kg) were administered by gavage daily for 15 consecutive days. The body weight, skin thickness, skin dermatitis severity and scratching behaviors were recorded throughout the study. Histological analysis, reverse transcription-quantitative polymerase chain reaction (RT-PCR), western blot (WB) and ELISA analysis were used to illuminate the molecular targets associated with the anti-AD effects of SZF.

RESULTS

SZF markedly decreased the epidermal thickening and infiltration of mast cells in the ears and dorsal skin of the 2,4-dinitrochlorobenzene (DNCB)-treated mice. SZF not only suppressed the levels of immunoglobulin E (IgE), histamine, thymic stromal lymphopoietin (TSLP) and IL-4 in the serum but also suppressed the over-production of IL-4 and IL-6 and gene expressions of IL-4, IL-13, IL-31 and TSLP in the dorsal skin. Moreover, SZF improved epidermal barrier by increasing the protein expressions of filaggrin, involucrin and loricrin and inhibited the activation of NF-κB p65 pathway in the dorsal skin of the DNCB-treated mice.

CONCLUSION

SZF alleviates DNCB induced AD-like skin lesions in mice through regulating Th1/Th2 balance, improving epidermal barrier and inhibiting skin inflammation. Our research findings provide scientific footing on the use of this Chinese herbal formula for the treatment of AD.

Therapeutic applications of the cancer immunoediting hypothesis

Since the late 19th century, the immune system has increasingly garnered interest as a novel avenue for cancer therapy, particularly given scientific breakthroughs in recent decades delineating the fundamental role of the immune system in tumorigenesis. The immunoediting hypothesis has articulated this role, describing three phases of the tumor-immune system interaction: Elimination, Equilibrium, and Escape wherein tumors progress from active immunologic surveillance and destruction through dynamic immunologic stasis to unfettered growth. The primary goals of immunotherapy are to restrict and revert progression through these phases, thereby improving the immune system's ability to control tumor growth. In this review, we detail the development and foundation of the cancer immunoediting hypothesis and apply this hypothesis to the dynamic immunotherapy field that includes checkpoint blockade, vaccine therapy, and adoptive cell transfer.

Regulatory T cells: Possible mediators for the anti-inflammatory action of statins

Statins beside their main effect on reducing the progression of cardiovascular disease through pharmacological inhibition of the endogenous cholesterol synthesis, have additional pleiotropic effects including antiinflammatory effects mediated through the induction of suppressor regulatory T cells (Tregs). Statin-induced expansion of Tregs reduces chronic inflammation and may have beneficial effects in autoimmune diseases. However, statins could represent a double-edged sword in immunomodulation. Drugs that act by increasing the concentration of Tregs could enhance the risk of cancers, particularly in the elderly and may have adverse effects in neurodegenerative disorders and infectious diseases. In the present paper, we review the experimental studies that evaluate the effects of statins on Treg cells in autoimmune and inflammatory diseases and we discuss potential therapeutic applications of statins in this setting.

Chinese Society of Allergy Guidelines for Diagnosis and Treatment of Allergic Rhinitis

Allergic rhinitis (AR) is a global health problem that causes major illnesses and disabilities worldwide. Epidemiologic studies have demonstrated that the prevalence of AR has increased progressively over the last few decades in more developed countries and currently affects up to 40% of the population worldwide. Likewise, a rising trend of AR has also been observed over the last 2-3 decades in developing countries including China, with the prevalence of AR varying widely in these countries. A survey of self-reported AR over a 6-year period in the general Chinese adult population reported that the standardized prevalence of adult AR increased from 11.1% in 2005 to 17.6% in 2011. An increasing number of Journal Articles and imporclinical trials on the epidemiology, pathophysiologic mechanisms, diagnosis, management and comorbidities of AR in Chinese subjects have been published in international peer-reviewed journals over the past 2 decades, and substantially added to our understanding of this disease as a global problem. Although guidelines for the diagnosis and treatment of AR in Chinese subjects have also been published, they have not been translated into English and therefore not generally accessible for reference to non-Chinese speaking international medical communities. Moreover, methods for the diagnosis and treatment of AR in China have not been standardized entirely and some patients are still treated according to regional preferences. Thus, the present guidelines have been developed by the Chinese Society of Allergy to be accessible to both national and international medical communities involved in the management of AR patients. These guidelines have been prepared in line with existing international guidelines to provide evidence-based recommendations for the diagnosis and management of AR in China.

IL-35 may maintain homeostasis of the immune microenvironment in periodontitis

T lymphocyte cells, including regulatory T (Treg) and T helper 17 cells, have important roles in the human periodontium. However, the basis for Treg cytokine expression in various compartments of the periodontium remains unclear. The aim of the present study was to investigate the expression of interleukin (IL)-35 in the peripheral blood mononuclear cells (PBMCs) and periodontal tissues of patients with chronic periodontitis (CP), with a view to understanding its role in this disease, and ultimately providing improved treatments. Peripheral blood, periodontal tissues and gingival crevicular fluids (GCFs) were collected from patients with CP or impacted teeth, the latter serving as healthy controls. The expression levels of IL-35 subunit mRNAs in PBMCs and periodontal tissues were determined using reverse transcription-quantitative polymerase chain reaction, while the IL-35 protein expression in GCFs and sera was quantified by ELISA. The relative expression of IL-35 subunit mRNAs in the affected tissues of patients with CP was significantly higher compared with that in samples from healthy controls (P<0.05). The mean concentration of IL-35 protein in the GCFs and sera of patients with periodontitis was also significantly higher compared with that in samples from healthy controls (P<0.001). IL-35 protein and periodontal clinical indicators were negatively correlated. It was hypothesized that the increased level of IL-35 plays a protective role in periodontal disease by maintaining immune system homeostasis and dampening the inflammatory response, and highlights IL-35 as a potential new therapy for the treatment of periodontitis.

Prenatal environmental tobacco smoke exposure increases allergic asthma risk with methylation changes in mice

Allergic asthma remains an inadequately understood disease. In utero exposure to environmental tobacco smoke (ETS) has been identified as an environmental exposure that can increase an individual's asthma risk. To improve our understanding of asthma onset and development, we examined the effect of in utero ETS exposure on allergic disease susceptibility in an asthmatic phenotype using a house dust mite (HDM) allergen-induced murine model. Pregnant C57BL/6 mice were exposed to either filtered air or ETS during gestation, and their offspring were further exposed to HDM at 6-7 weeks old to induce allergic inflammation. Methylation in the promoter regions of allergic inflammation-related genes and genomic DNA was quantified. Exposure to HDM resulted in the onset of allergic lung inflammation, with an increased presence of inflammatory cells, Th2 cytokines (IL-4, IL-5, and IL-13), and airway remodeling. These asthmatic phenotypes were significantly enhanced when the mice had been exposed to in utero ETS. Furthermore, prenatal ETS exposure and subsequent HDM (ETS/HDM)-induced asthmatic phenotypes agree with methylation changes in the selected asthma-related genes, including IL-4, IL-5, IL-13, INF-γ, and FOXP3. Global DNA methylation was significantly lower in ETS/HDM-exposed mice than that of controls, which coincides with the results observed in lung, spleen, and blood DNAs. Prenatal ETS exposure resulted in a severe increase in allergic inflammatory responses after an HDM challenge, with corresponding methylation changes. Prenatal ETS exposure may influence developmental plasticity and result in altered epigenetic programming, leading to an increased susceptibility to asthma. Environ. Mol. Mutagen. 58:423-433, 2017. © 2017 Wiley Periodicals, Inc.

The Role of Vitamin D in the Immune System as a Pro-survival Molecule

PURPOSE

Vitamin D is a fascinating and attractive molecule that has gained particular attention in medicine in recent years. Its immunomodulatory and anti-inflammatory potential might resemble the activity of many nature-derived molecules (eg, flavonoids), but its role in biology was selected during a long evolutionary pathway to dampen the damaging effect of cell stress response and of the immune reaction. In this sense, this molecule can be considered an ancient hormone that serves, in its primary role, as a pro-survival agent. The goal of this review was to elucidate this topic.

METHODS

The article reviews current literature on the field, focusing on issues regarding the role of vitamin D in immunity.

FINDINGS

Vitamin D participates in the survival machinery used by the cell, and in particular it plays a major role in synchronizing calcium oscillatory signaling to allow cell autophagy or apoptosis during a stress response.

IMPLICATIONS

Vitamin D should be better highlighted in its molecular action and vitamin D receptor genomics to conceive a more suited therapeutic supplementation protocol in clinics.

Subsets of regulatory T cells and their roles in allergy

In recent years, it is recognized that acquired immunity is controlled by regulatory T cell (Treg). Since fundamental pathophysiological changes of allergy are mainly caused by hyperresponsiveness of immune system to allergens that acquires after birth, Tregs likely play key roles in the pathogenesis of allergy, particularly during the sensitization phase. However, accumulated information indicate that there are several distinctive subtypes of Tregs in man, and each of them seems to play different role in controlling immune system, which complicates the involvement of Tregs in allergy. The aim of the present study is to attempt to classify subtypes of Tregs and summarize their roles in allergy. Tregs should include natural Tregs (nTreg) including inducible costimulator (ICOS)(+) Tregs, inducible/adaptive Tregs (iTreg), interleukin (IL)-10-producing type 1 Tregs (Tr1 cells), CD8(+) Tregs and IL-17-producing Tregs. These cells share some common features including expression of Foxp3 (except for Tr1 cells), and secretion of inhibitory cytokine IL-10 and/or TGF-β. Furthermore, it is noticeable that Tregs likely contribute to allergic disorders such as dermatitis and airway inflammation, and play a crucial role in the treatment of allergy through their actions on suppression of effector T cells and inhibition of activation of mast cells and basophils. Modulation of functions of Tregs may provide a novel strategy to prevent and treat allergic diseases.

The Imbalance of Th17 cells and CD4(+) CD25(high) Foxp3(+) Treg cells in patients with atopic dermatitis

BACKGROUND

Th17/Treg imbalance is involved in several autoimmune, inflammatory and allergic reactions. Nevertheless, the possible contribution of Th17/Treg imbalance in atopic dermatitis (AD) remains unknown.

OBJECTIVE

To explore the possible role of Th17/Treg imbalance in AD.

METHODS

Th17 and Treg cells percentage in peripheral blood mononuclear cells (PBMCs) and skin specimens, specific transcription factor retinoic acid-related orphan receptor (ROR)γt and Foxp3 mRNA levels in PBMCs, as well as Th17- and Treg-related cytokines mRNA levels in PBMCs, serum concentrations, and expression levels in PBMCs culture supernatant after recombinant Dermatophagoides pteronyssinus antigen stimulation were detected in AD patients. Controls included patients with psoriasis, allergic contact dermatitis (ACD) and healthy donors.

RESULTS

Th17 cells percentage, RORγt, IL-17 and IL-23 levels in peripheral circulation of AD patients were significantly higher than those in ACD patients and healthy controls, but lower than those of psoriasis patients. Treg cells percentage, Foxp3 and TGF-β mRNA levels were reduced in AD patients compared with healthy controls, while there were no significant differences among AD, ACD and psoriasis patients. Th17 cells percentage, IL-17 and IL-23 levels were increased, while Treg cells percentage and TGF-β level were decreased in AD lesion and PBMCs culture supernatant respectively. There was a negative association between Th17 and Treg cells percentage in AD patients. AD severity score positively correlated with Th17 cells percentage and Th17/Treg ratio, while negatively correlated with Treg cells percentage. Serum IgE levels positively correlated with Th17/Treg ratio.

CONCLUSION

In AD, there exists an immune imbalance in Th17 and Treg cells, which may contribute to its pathogenesis and development.

The DNA methylation inhibitor 5-azacytidine increases regulatory T cells and alleviates airway inflammation in ovalbumin-sensitized mice

BACKGROUND

Asthma is characterized as a chronic inflammatory disorder of the airways associated with an enhanced TH2 response to inhaled allergens. CD4+ T regulatory (Treg) cells are controlled by the master transcription factor FoxP3 and strictly maintain peripheral immunotolerance. Epigenetic regulation of FoxP3 by DNA methyltransferase inhibitors, such as 5-azacytidine (Aza), can generate a steady supply of functional Treg cells. Therefore, we propose that Aza can augment Treg cells in vivo to prevent the pathogenesis of asthma.

METHODS

BALB/c mice were sensitized with chicken ovalbumin (OVA) and treated with different doses of Aza. Airway hyperresponsiveness to methacholine, eosinophilia in bronchoalveolar lavage fluid, circulating titers of OVA-specific IgG1 and IgE, and stimulating levels of TH2 cytokines from splenocytes were then determined. Cellular populations were examined by flow cytometry. PC61 antibody, which depletes CD25+ cells, was used to verify the role of CD25+ cells in Aza-induced tolerance.

RESULTS

Administration of Aza to OVA-sensitized mice diminished airway hyperreactivity, pulmonary eosinophilia, levels of OVA-specific IgG1 and IgE in serum, and secretion of TH2 cytokines from OVA-stimulated splenocytes in a dose-dependent manner. Percentages of CD25+ and FoxP3+ cells in the CD4+ cell population were notably increased in Aza-treated mice compared to sensitized control mice. Furthermore, the major symptoms of asthma were exacerbated by depleting CD25+ cells in Aza-treated mice.

CONCLUSIONS

Aza may have applications as a novel clinical strategy to increase the production of Treg cells in order to modulate the airway inflammation associated with asthma.

Regulatory B cells from hilar lymph nodes of tolerant mice in a murine model of allergic airway disease are CD5+, express TGF-β, and co-localize with CD4+Foxp3+ T cells

In a biphasic, ovalbumin (OVA)-induced murine asthma model where allergic airway disease is followed by resolution and the development of local inhalational tolerance (LIT), transforming growth factor (TGF)-β-expressing CD5(+) B cells were selectively expanded locally in hilar lymph nodes (HLN) of LIT mice. LIT HLN CD5(+) B cells, but not LIT HLN CD5(-) B cells, induced expression of Foxp3 in CD4(+)CD25(-) T cells in vitro. These CD5(+) regulatory B cells (Breg) and CD4(+)Foxp3(+) T cells demonstrated similar increases in expression of chemokine receptors (CXCR4 and CXCR5) and co-localized in HLN B cell zones of LIT mice. The adoptive transfer of LIT HLN CD5(+) B cells, but not LIT HLN CD5(-) B cells, increased the number of CD4(+)Foxp3(+) T cells in the lung and inhibited airway eosinophilia in this OVA model. Thus, Breg in HLNs of LIT mice reside in a CD5(+) TGF-β-producing subpopulation and co-localize with CD4(+)Foxp3(+) T cells.

Beneficial effects of sitostanol on the attenuated immune function in asthma patients: results of an in vitro approach

Background

In vitro and animal studies have suggested that plant sterols and stanols increase cytokine production by T-helper-1 cells. This may be beneficial for patient groups characterized by a T-helper-2 dominant immune response, e.g. asthma patients. (1) to evaluate whether sitostanol induces a T-helper-1 shift in peripheral blood mononuclear cells (PBMCs) from asthma patients, and (2) to unravel the role of regulatory T-cells in this respect.

Methodology/Principal Findings

PBMCs from 10 asthma patients and 10 healthy subjects were isolated and incubated with 1.2 µM sitostanol, while stimulated with 5 µg/ml PHA. Similar amounts of cholesterol were used to determine whether effects were specific for plant stanols or for sterols in general. Changes in cytokine production were measured using antibody arrays and ELISAs. Changes in regulatory T-cell population size were measured by flow cytometry, using intracellular Foxp3 staining. Sitostanol increased production of IFNγ by 6.5% and IL-2 by 6.0% compared to cholesterol (p<0.01). No changes in IL-4 and IL-13 were found. Interestingly, this effect was only present in PBMCs from asthma patients. The number of Foxp3+ cells tended to increase and their activity, measured by IL-10 production, increased after sitostanol treatment in PBMCs from asthma patients compared to controls by 32.3% (p = 0.077) and 13.3% (p<0.05), respectively.

Conclusions/Significance

Altogether, the sitostanol-induced Thelper-1 shift in PBMCs from asthma patients and the stimulating effects of sitostanol on Treg cell numbers and activity indicate a possible novel approach for plant stanol ester enriched functional foods in the amelioration of asthmatic symptoms. Functional effects, however, require further evaluation.

Impact of bacterial colonization on exhaled inflammatory markers in wheezing preschool children

Wheeze is a common symptom in preschool children. The role of bacteria, regulatory T (T(reg)) cells and their association with airway inflammation in preschool wheeze is largely unknown. We evaluated inflammatory markers in exhaled breath condensate (EBC), bacterial colonization and circulating T(reg) cells in preschool children with and without recurrent wheeze. We recruited 252 children (aged two to four years) with (N = 202) and without (N = 50) recurrent wheeze. EBC was collected using an efficient closed glass condenser. Inflammatory markers in EBC (Interleukin(IL)-2, IL-4, IL-8, IL-10, IL-13) were assessed using multiplex immunoassay. Nasal and throat swabs were analysed for presence of Streptococcus pneumoniae, Haemophilus (para)influenzae and Staphylococcus aureus. Proportions of T(reg) cells (CD4(+)CD25(high)CD127(-)) were quantified by flow cytometry. Recurrent wheezing children had elevated EBC levels of IL-2, IL-4, IL-10 and IL-13 compared to non-wheezers (odds ratio (95% confidence interval): 1.67 (1.23-2.27): 1.58 (1.15-2.18): 1.47 (1.14-1.90): 1.55 (1.16-2.06), p <0.05, respectively). Bacteria were frequently present in children with and without wheeze, with no difference in prevalence (16-52% versus 16-50%, respectively). Moreover, the proportion of T(reg) cells did not differ between both groups. Wheezing children with bacterial colonization did not significantly differ in exhaled levels of inflammatory markers or proportion of T(reg) cells compared to wheezing children without colonization. The analysis of EBC might serve as a helpful non-invasive tool to early assess airway inflammation in wheezing children. The various elevated exhaled inflammatory markers indicate increased airway inflammation in wheezing preschool children. In the presence of wheeze, we found no evidence for bacterial induced airway inflammation.

Heligmosomoides polygyrus abrogates antigen-specific gut injury in a murine model of inflammatory bowel disease

BACKGROUND

Developing countries have a low incidence of inflammatory bowel disease (IBD), perhaps prevented by the high prevalence of helminth infections and other alterations in intestinal flora and fauna. Helminth infections prevent colitis in various murine models of IBD. IBD may be driven by an aberrant immune response to luminal antigen(s).

METHODS

We developed a murine model of IBD in which gut injury was induced by a specific antigen to better simulate the IBD disease process and to determine if helminth infections could abolish gut injury induced by an orally administered antigen. The model features pan-enterocolitis triggered by feeding ovalbumin (OVA).

RESULTS

The intestinal inflammation is antigen-specific and generates interleukin (IL)-17 and interferon-gamma (IFN-γ), but not IL-4. Full expression of the disease required T cells with defective capacity to make IL-10 and treatment with a noninjurious, low dose of a nonsteroidal antiinflammatory drug. Exposure to Heligmosomoides polygyrus abrogated this antigen-induced gut injury. H. polygyrus colonization induced Foxp3(+) T regulatory cells (Tregs) and mucosal production of IL-10 from non-T cells. Lamina propria mononuclear cells from H. polygyrus-infected mice released less IL-17 and IFN-γ constitutively and when stimulated with OVA or anti-CD3/CD28 monoclonal antibodies.

CONCLUSIONS

We developed a murine IBD model featuring antigen-specific enterocolitis and demonstrate for the first time that gut inflammation induced by an antigen could be abrogated by H. polygyrus infection. Protection was associated with suppressed IL-17 and IFN-γ production, induction of Foxp3(+) Tregs, and elevated secretion of non-T-cell-derived IL-10, all of which could be part of the protective processes.

The attenuation of cockroach allergy by DNA vaccine encoding cockroach allergen Bla g 2

Bla g 2 is one of the most potent cockroach allergens. No effective treatment or vaccination strategies are yet available. We evaluated the prophylactic efficacy of Bla g 2 DNA vaccination in a mouse model of allergic airway inflammation. C57/BL6 mice were given Bla g 2 DNA vaccine prior to sensitization with recombinant Bla g 2 (rBla g 2) antigens, followed by nebulized rBla g 2 challenge. Bla g 2 vaccine could express at both transcriptional and translational levels in mammalian cells. Moreover, Bla g 2 vaccine significantly reduced the total inflammatory cell infiltrate and eosinophilia in bronchoalveolar lavage fluid, and markedly decreased allergen-induced inflammatory infiltrates in the lungs and Bla g 2-specific IgE in serum upon challenge with rBla g 2. Importantly, Bla g 2 vaccine could induce the production of antigen-specific IFN-γ and downregulated Th2 pro-inflammatory cytokines IL-4, IL-5, and IL-13. Thus, DNA vaccination showed protective efficacy against a clinically relevant allergen, Bla g 2.

T cell-derived IL-10 and its impact on the regulation of host responses during malaria

Despite intense research, malaria still is the one of the most devastating diseases killing more people than any other parasitic infection. In an attempt to control the infection, the host immune system produces a potent pro-inflammatory response. However, this response is also associated with complications, such as severe anaemia, hypoglycaemia and cerebral malaria. This pronounced production of pro-inflammatory cytokines response is a common feature of malaria caused by parasites infecting humans as well as rodents and primates. A balance between pro- and anti-inflammatory responses may be fundamental to the elimination of the parasite without inducing excessive host pathology. IL-10 is a key cytokine that has been shown to have an important regulatory function in establishing this balance in malaria. Here we discuss which cells can produce IL-10 during infection, and present an overview of the evidence showing that T-cell derived IL-10 plays an important role in regulating malaria pathology. Many different subsets of T cells can produce IL-10, however, evidence is accumulating that it is effector Th1 CD4(+) T cells which provide the crucial source that down-regulates inflammatory pathology during blood-stage malaria infections.

Prevention and treatment of DNA vaccine encoding cockroach allergen Bla g 1 in a mouse model of allergic airway inflammation

BACKGROUND

One-fourth of the US population is sensitized to the German cockroach. Primary German cockroach allergen Bla g 1 is detected in 63% of homes and 52% of childcare facilities in the United States. No effective treatment or vaccination strategies are yet available.

OBJECTIVES

We evaluated the prophylactic and therapeutic efficacy of a plasmid DNA-mediated vaccination using the Bla g 1 gene in a mouse model of allergic inflammatory airway disease.

METHODS

A plasmid DNA vector coding for the Bla g 1 allergen controlled by cytomegalovirus promoter was constructed. To estimate the protective efficacy, BALB/c mice were given three injections of plasmid DNA-Bla g 1 prior to sensitization with two priming doses of recombinant Bla g 1 (rBla g 1) antigens, followed by nebulized rBla g 1 challenge. In the therapeutic approach, sensitization was followed by administering Bla g 1 DNA vaccine.

RESULTS

Bla g 1 vaccination significantly reduced allergen-induced airway inflammation, even after mice were presensitized and a Th2-dominant response was established. The Bla g 1 vaccination significantly reduced total inflammatory cell infiltrate, eosinophilia, secretion of Th2 cytokines IL-4 and IL-5 in bronchoalveolar lavage fluid, allergen-induced inflammatory infiltrates in the lungs, and Bla g 1-specific IgE in serum upon challenge with rBla g 1. Importantly, Bla g 1 DNA vaccination was able to induce IL-10-secreting regulatory T cells that could suppress the allergen-specific Th2 cells.

CONCLUSION

DNA vaccination showed protective and therapeutic efficacy against a clinically relevant allergen Bla g 1.

Early oral ovalbumin exposure during maternal milk feeding prevents spontaneous allergic sensitization in allergy-prone rat pups

There are conflicting data to support the practice of delaying the introduction of allergenic foods into the infant diet to prevent allergy development. This study investigated immune response development after early oral egg antigen (Ovalbumin; OVA) exposure in a rat pup model. Brown Norway (BN) rat pups were randomly allocated into groups: dam reared (DR), DR pups challenged daily (days 4–13) with oral OVA (DR + OVAc), DR pups challenged intermittently (on day 4, 10, 12, and 13) with oral OVA (DR + OVAi), formula-fed pups (FF), and FF pups challenged daily with oral OVA (FF + OVA). Immune parameters assessed included OVA-specific serum IgE, IgG1, and IgA. Ileal and splenic messenger ribonucleic acid (mRNA) expression of transforming growth factor-beta (TGF-β1), mothers against decapentaplegic (Smad) 2/4/7, and forkhead box P3 (Foxp3) were determined. Ileum was stained for TGF-β1 and Smad4. Results. Feeding OVA daily to DR pups maintained systemic and local gut antibody and immunoregulatory marker mRNA responses. Systemic TGF-β1 was lower in DR + OVAi pups compared to DR and DR + OVAc pups. Feeding OVA to FF pups resulted in significantly greater OVA-specific IgE and IgG1, and lower IgA and TGF-β1 and Smad expression compared to DR pups. Conclusions. Early daily OVA exposure in the presence of maternal milk maintains immune markers associated with a regulated immune response, preventing early allergic sensitization.

The role of female hormones on lung function in chronic lung diseases

Background

The prevalence, morbidity, and mortality of inflammatory lung diseases such as asthma, chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF) are increasing in women. There is a dearth of data on the biological mechanisms to explain such observations. However, some large epidemiologic studies suggest that lung function fluctuates during the menstrual cycle in female patients with airways disease but not in women without disease, suggesting that circulating estradiol and progesterone may be involved in this process.

Discussion

In asthma, estradiol shuttles adaptive immunity towards the T_H2 phenotype while in smokers estrogens may be involved in the generation of toxic intermediate metabolites in the airways of female smokers, which may be relevant in COPD pathogenesis. In CF, estradiol has been demonstrated to up-regulate MUC5B gene in human airway epithelial cells and inhibit chloride secretion in the airways. Progesterone may augment airway inflammation.

Summary

Taken together, clinical and in-vivo data have demonstrated a sex-related difference in that females may be more susceptible to the pathogenesis of lung diseases. In this paper, we review the effect of female sex hormones in the context of these inflammatory airway diseases.

A superagonistic monoclonal antibody for CD28 ameliorates crescentic glomerulonephritis in wistar-kyoto rats

Regulatory T (Treg) cells play an important role in the resolution of crescentic glomerulonephritis, where a T helper 1 (Th1)-predominant immune response promotes crescent formation. Therefore, agents that increase Treg cells appear to be ideal for suppressing T-cell-mediated renal pathology. We hypothesized that a superagonistic monoclonal antibody for CD28 (JJ316), which has been known to preferentially expand Treg cells in vivo, could prevent nephrotoxic serum-induced nephritis in Wistar-Kyoto rats, one of the experimental models of crescentic glomerulonephritis. Administration of JJ316 attenuated crescent formation, proteinuria and glomerular accumulation of macrophages and CD8(+) T cells. These changes were accompanied by increased infiltration of Treg cells. Among glomerular macrophages, the CD163(+) subset was significantly increased after treatment, suggesting that Treg cells may modulate the phenotype of macrophages leading to resolution of glomerulonephritis. In an adoptive transfer experiment, two T-cell subsets (CD4(+)CD25(+) and CD4(+)CD25(-) T cells) purified from spleens and lymph nodes of donor rats primed with JJ316 3 d before were inoculated into nephritic recipient rats, which recapitulated the beneficial effects of in vivo administration of JJ316. Furthermore, a single injection of JJ316 administered 3 d after disease induction completely protected nephritic rats from death for 2 months. In conclusion, we demonstrated that treatment with JJ316 has a dramatic therapeutic effect on an experimental crescentic glomerulonephritis, possibly due to expansion and activation of Treg cells.

FOXP3, IL-10, and TGF-β genes expression in children with IgE-dependent food allergy

BACKGROUND

Regulatory T cells (Tregs) have an essential role in tolerance and immune regulation. However, few and controversial data have been published to date on the role and number of these cells in food allergic children. The forkhead/winged-helix transcription factor box protein 3 (FOXP3) is considered the most reliable marker for Tregs.

OBJECTIVE

This study aims to investigate the FOXP3, interleukin (IL)-10, and transforming growth factor (TGF-β) genes expression in children with IgE-dependent food allergy.

MATERIAL AND METHODS

The study group consisted of 54 children with IgE-dependent food allergy (FA) and a control group of 26 non-atopic healthy children. The diagnosis of FA was established using questionnaires, clinical criteria, skin prick tests, serum sIgE antibodies (UniCAP 100 Pharmacia Upjohn), and a double-blind placebo control food challenge. In order to assess gene expression, the isolation of nucleated cells was performed using Histopaque-1077 (Sigma-Aldrich, Germany). The concentration of RNA obtained was measured using a super-sensitive NanoDrop ND1000 spectrophotometer (Thermo Scientific, USA). A reverse transcription reaction was performed using a commercially available set of High Capacity cDNA Archive Kit (Applied Biosystems, USA). Analysis have been carried out in the genetic analyzer 7900HT Real-Time PCR (Applied Biosystems, USA).

RESULTS

The average level of the FOXP3 gene expression in the studied group was 2.19 ± 1.16 and in the control group 2.88 ± 1.66 (p = 0.03). The average level of IL10 mRNA expression in the study group was 13.6 ± 1.07 and was significantly lower than corresponding values in the control group 14.3 ± 1.1 (p = 0.01). There were no significant differences in the average level of the TGF-β mRNA expression in the study group (3.4 ± 0.4) and controls (3.5 ± 0.3; p > 0.05). The FOXP3 gene expression was the highest in children who acquired tolerance to food (3.54 ± 0.75), lower in heated allergen-tolerant children (2.43 ± 0.81), and the lowest in heated allergen-reactive children (1.18 ± 0.5; p = 0.001 control vs heated allergen reactive; p = 0.005 heated allergen tolerant vs heated allergen reactive; p = 0.001 outgrown vs heated allergen reactive). The significant tendency toward lower total IgE levels with a higher FOXP3 mRNA expression was detected (n = 54; Pearson r = -0.4393; p = 0.001).

CONCLUSIONS

Children with FA showed statistically significant lower level of the FOXP3 and IL10 gene expression than healthy children. Children acquiring tolerance to the food show significantly higher levels of the FOXP3 gene expression than children with active FA. The correlation between the level of FOXP3 and total IgE was detected.

Interplay between TNF and regulatory T cells in a TNF-driven murine model of arthritis

CD4(+)CD25(+)Foxp3(+) regulatory T cells (Treg) are involved in several autoimmune diseases, including rheumatoid arthritis. TNF-α blockers induce therapeutic benefits in rheumatoid arthritis via a variety of mechanisms. We aimed to characterize the impact on Treg of TNF-α overexpression in vivo and of TNF-α inhibiting treatments. We used human TNF-α transgenic mice as a model of strictly TNF-α-dependent arthritis. Our study showed that initial Treg frequency was lower in TNF-α transgenic mice than in wild-type mice. However, the course of arthritis was marked by elevation of Treg frequency and a dramatic increase in expression of TNFR2. Antagonizing TNF-α with either the anti-human TNF-α Ab (infliximab) or active immunotherapy (TNF-kinoid) increased the Treg frequency and upregulated CTLA-4, leading to enhancement of suppressor activity. Moreover, both anti-TNF-α strategies promoted the differentiation of a CD62L(-) Treg population. In conclusion, in an in vivo model of TNF-α-driven arthritis, Treg frequency increased with inflammation but failed to control the inflammatory process. Both passive and active TNF-α-inhibiting strategies restored the suppressor activity of Treg and induced the differentiation of a CD62L(-) Treg population.

Laboratorial atopy markers in children with human immunodeficiency virus

Changes in immune system functions are one of the most important consequences of human immunodeficiency virus (HIV) infection. Studies have reported a higher prevalence of disease mediated by immunological hypersensitivity mechanisms in HIV-positive patients. This study aims to observe how immunological changes in HIV-infected children interfere in atopy determinants. Fifty-seven HIV-positive children were studied between June 2004-August 2005 to evaluate the possible modifications in atopy diagnosis from prick test environmental allergen reactivity. Patients were subjected to two evaluations: on both occasions, atopic and non-atopic groups were correlated with immunological (CD4+ and CD8+ lymphocyte concentrations and serum levels of IgA, IgM, IgG and IgE) and viral parameters (HIV viral load). The percent atopy was 20.05 in the first and 29.82 in the second evaluation and atopy was diagnosed in patients without immunosuppression or with moderate immunosuppression. Six patients changed from a negative to a positive atopy profile. One patient with a decreased CD4+ T lymphocyte concentration failed to demonstrate prick test positivity between evaluations. Multivariate analysis showed that the variables associated with atopy diagnosis included a personal history of allergic diseases as well as elevated IgE for age and elevated IgE levels. Atopy development in HIV-infected children seems to be modulated by genetic and environmental factors as well as immunological condition.

Gender differences in transcriptional regulation of IL-5 expression by bronchial lymph node cells in a mouse model of asthma

BACKGROUND AND OBJECTIVE

The severity of asthma after puberty is higher in women than in men. Increased numbers of eosinophils in the airways of female mice after antigen challenge was associated with increased levels of T helper (Th)2 cytokines at the site of inflammation, and in human and mouse studies, the profile of cytokines produced by immune cells from women showed greater Th2 predominance. The aim of this study was to investigate gender differences in the development of Th2 immune responses.

METHODS

Male and female C57BL/6 mice were sensitized with ovalbumin. Cells prepared from bronchial lymph nodes were cultured in the absence or presence of ovalbumin. Cytokine concentrations in the culture supernatants were measured, and IL-5 and GATA-binding protein 3 (GATA-3) gene expression were evaluated. T-cell subsets were analysed using specific surface markers.

RESULTS

The concentrations of IL-4, IL-5, IL-13 and IL-10, but not interferon-gamma or transforming growth factor-beta(1), were higher in cell supernatants from female mice than in those from male mice. IL-5 and GATA-3 gene expressions were higher in cells from women than in cells from men. The numbers of CD3(+)CD4(+)T1/ST2(+) cells, but not CD3(+)CD4(+) or CD4(+)CD25(+) cells, were significantly higher in cells from women than in cells from men.

CONCLUSIONS

Greater antigen-induced Th2 cytokine production by bronchial lymph node cells from female mice was associated with enhanced Th2 cell differentiation and increased expression of the Th2-specific transcription factor, GATA-3.

Hormonal influences on lung function and response to environmental agents: lessons from animal models of respiratory disease

Numerous studies in humans and experimental animals have identified considerable sex differences in respiratory physiology and in the response of the lung to environmental agents. These differences appear to be mediated, at least in part, by sex hormones and their nuclear receptors. Moreover, animal models are increasingly used to study pathogenic mechanisms and test potential therapies for a variety of human lung diseases, many of which appear to be influenced by sex and sex hormones. In this article, data are summarized from studies of lung function and disease in which sex differences have been observed. Specific attention is paid to animal models of acute lung injury, nonallergic and allergic lung inflammation, and lung fibrosis. It is anticipated that continued investigation of the role of sex and sex hormones in animal models will provide valuable insight into the pathogenesis and potential treatments for a variety of acute and chronic human lung diseases.

Guidance for substantiating the evidence for beneficial effects of probiotics: prevention and management of allergic diseases by probiotics

Allergy is a hypersensitivity reaction mediated by specific antibody-mediated or cell-mediated immunologic mechanisms and clinically manifested as atopic eczema, allergic rhinoconjunctivitis, or asthma. During the recent decades there has been an increase in allergy prevalence, which is attributed to changes in environmental factors. The so-called "hygiene hypothesis" suggests that a lack of exposure to microbial stimulus early in childhood is a major factor involved in this trend. This provides a rationale for using probiotics to modify the gut microbiota and thereby shaping the immune response of the host, especially in infancy. Most success has been obtained in primary prevention of atopic eczema. A limited number of studies also provided evidence for a beneficial effect of different probiotics in the management of allergic diseases (atopic eczema, allergic rhinitis). However, choice of probiotic strains as well as timing of the intervention are important variables. The exact in vivo mechanism of probiotics in shaping the immune response still needs to be determined. Future studies should use uniform criteria for diagnosis and symptom scoring of atopic diseases and may identify the genes predisposing to allergic disease. There is encouraging evidence that specific probiotics can become valuable tools in the prevention and management of allergic diseases.

Milk-derived transforming growth factor-beta and the infant immune response

Breast milk cytokines have the potential to regulate the immune response to food antigens in infants. Cytokines are present in all mammalian milks and are capable of inhibiting excess inflammation and modulating epithelial proliferation. There are a range of candidate cytokines in milk such as transforming growth factor-beta (TGF-beta), the major cytokine present, and interleukin-10, which play a role in immune regulation in the developing infant. This article will be a review of the current literature with regard to TGF-beta in infant immune development. Our data on supplementation of formula with rTGF-beta2 will be discussed in view of the current literature. Oral antigen exposure also plays an important role in priming the developing immune response. The influence of early introduction of oral beta-lactoglobulin in allergy prone rat pups will also be discussed.

Regulation of type 1 diabetes, tuberculosis, and asthma by parasites

Helminth infection is a worldwide health problem. In addition to directly causing disease, helminthic infection also affects the incidence and progression of other diseases by exerting immune modulatory effects. In animal models, infection with helminthic parasites can prevent autoimmune diseases and allergic inflammatory diseases, but worsens protective immunity to certain infectious pathogens. In this review, we summarize current findings regarding the effects of helminth infection on type 1 diabetes, tuberculosis, and asthma and discuss possible mechanisms through which helminthic parasites modulate host immunity. Investigating these mechanisms could lead to treatment strategies that specifically modulate the immune response as well as address fundamental questions in immunobiology.

Innate and adaptive immunity for the pathobiology of Parkinson's disease

Innate and adaptive immunity affect the pathogenesis of Parkinson's disease (PD). In particular, activation of microglia influences degeneration of dopaminergic neurons. Cell-to-cell interactions and immune regulation critical for neuronal homeostasis also influence immune responses. The links between T cell immunity and nigrostriatal degeneration are supported by laboratory, animal model, and human pathologic investigations. Immune-associated biomarkers in spinal fluids and brain tissue of patients with idiopathic or familial forms of PD provide means to improve diagnosis and therapeutic monitoring. Relationships between oxidative stress, inflammation, and immune-mediated cell death pathways are examined in this review as they are linked to PD pathogenesis. Harnessing the immune system by drugs or by vaccination remain promising future therapeutic options.

Early diagnosis of asthma in young children by using non-invasive biomarkers of airway inflammation and early lung function measurements: study protocol of a case-control study

Background

Asthma is the most common chronic disease in childhood, characterized by chronic airway inflammation. There are problems with the diagnosis of asthma in young children since the majority of the children with recurrent asthma-like symptoms is symptom free at 6 years, and does not have asthma. With the conventional diagnostic tools it is not possible to differentiate between preschool children with transient symptoms and children with asthma. The analysis of biomarkers of airway inflammation in exhaled breath is a non-invasive and promising technique to diagnose asthma and monitor inflammation in young children. Moreover, relatively new lung function tests (airway resistance using the interrupter technique) have become available for young children. The primary objective of the ADEM study (Asthma DEtection and Monitoring study), is to develop a non-invasive instrument for an early asthma diagnosis in young children, using exhaled inflammatory markers and early lung function measurements. In addition, aetiological factors, including gene polymorphisms and gene expression profiles, in relation to the development of asthma are studied.

Methods/design

A prospective case-control study is started in 200 children with recurrent respiratory symptoms and 50 control subjects without respiratory symptoms. At 6 years, a definite diagnosis of asthma is made (primary outcome measure) on basis of lung function assessments and current respiratory symptoms ('golden standard'). From inclusion until the definite asthma diagnosis, repeated measurements of lung function tests and inflammatory markers in exhaled breath (condensate), blood and faeces are performed. The study is registered and ethically approved.

Discussion

This article describes the study protocol of the ADEM study. The new diagnostic techniques applied in this study could make an early diagnosis of asthma possible. An early and reliable asthma diagnosis at 2–3 years will have consequences for the management of the large group of young children with asthma-like symptoms. It will avoid both over-treatment of children with transient wheeze and under-treatment of children with asthma. This might have a beneficial influence on the prognosis of asthma in these young children. Besides, insight into the pathophysiology and aetiology of asthma will be obtained.

TRIAL REGISTRATION

This study is registered by clinicaltrials.gov (NCT00422747).

How regulatory T cells work

Regulatory T (T(Reg)) cells are essential for maintaining peripheral tolerance, preventing autoimmune diseases and limiting chronic inflammatory diseases. However, they also limit beneficial responses by suppressing sterilizing immunity and limiting antitumour immunity. Given that T(Reg) cells can have both beneficial and deleterious effects, there is considerable interest in determining their mechanisms of action. In this Review, we describe the basic mechanisms used by T(Reg) cells to mediate suppression and discuss whether one or many of these mechanisms are likely to be crucial for T(Reg)-cell function. In addition, we propose the hypothesis that effector T cells may not be 'innocent' parties in this suppressive process and might in fact potentiate T(Reg)-cell function.

Scalable signaling mediated by T cell antigen receptor-CD3 ITAMs ensures effective negative selection and prevents autoimmunity

The T cell antigen receptor (TCR)-CD3 complex is unique in having ten cytoplasmic immunoreceptor tyrosine-based activation motifs (ITAMs). The physiological importance of this high TCR ITAM number is unclear. Here we generated 25 groups of mice expressing various combinations of wild-type and mutant ITAMs in TCR-CD3 complexes. Mice with fewer than seven wild-type CD3 ITAMs developed a lethal, multiorgan autoimmune disease caused by a breakdown in central rather than peripheral tolerance. Although there was a linear correlation between the number of wild-type CD3 ITAMs and T cell proliferation, cytokine production was unaffected by ITAM number. Thus, high ITAM number provides scalable signaling that can modulate proliferation yet ensure effective negative selection and prevention of autoimmunity.

Regulatory T cell therapy as individualized medicine for asthma and allergy

PURPOSE OF REVIEW

Regulatory T cells have been identified as key players in the maintenance of peripheral tolerance, which prevents inappropriate immune responses to both self-antigens and innocuous allergens. This review aims to provide an update on our current understanding of the therapeutic potential of naturally occurring and adaptive regulatory T cell subsets in allergic and asthmatic disease.

RECENT FINDINGS

Evidence is emerging that regulatory T cells control aberrant immune responses to allergens in health and exhibit impaired function in active disease. These data provide a rationale for developing therapeutic strategies that promote regulatory T cell numbers or function in patients.

SUMMARY

Preclinical studies of adoptive transfer of antigen-specific regulatory T cells into mouse models of allergic airway disease ameliorate the inflammatory response and in some studies airway hyperresponsiveness. Although these studies are encouraging this remains an invasive and expensive therapeutic protocol for the treatment of allergic disease in humans and a number of concerns relating to safety and efficacy exist. Existing therapies, both allergen specific immunotherapy and nonspecific treatments such as glucocorticoids, induce IL-10 secreting T regulatory populations in patients. Strategies to combine allergen immunotherapy with add-on treatments or adjuvants with the potential to boost regulatory T cells, safety and efficacy remain a major research focus.

Resolution of Der p1-induced allergic airway inflammation is dependent on CD4+CD25+Foxp3+ regulatory cells

Allergic airway inflammation (AAI) is characterized by airway hyperreactivity, eosinophilia, goblet cell hyperplasia, and elevated serum IgE, however, it is unclear what mediates natural resolution after cessation of allergen exposure. This is important because the outcome of subsequent allergen challenge may depend on the concurrent inflammatory milieu of the lung. Using a murine AAI model, we demonstrate that after exposure to a defined natural protein allergen, Der p1, the response in lungs and draining mediastinal lymph nodes (dMLN) peaks between 4 and 6 days then declines until resolution by 21 days. Der p1-specific serum IgE follows the same pattern while IgG1 continues to increase. Resolution of AAI is mediated by CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs), which appear in lungs and dMLN following airway challenge. Treg depletion exacerbated lung eosinophilia, increased dMLN IL-5 and IL-13 but not IL-10 secretion, and increased allergic Ab responses. Most convincingly, transfer of CD4(+)CD25(+)Foxp3(+) T cells from Ag naive mice (natural Tregs) abolished AAI, decreased dMLN IL-5 and IL-13 secretion, increased dMLN IL-10 secretion, abolished IgE, and decreased IgG1 Abs. Blocking IL-10 receptor function in vivo did not block the anti-inflammatory function of transferred natural Tregs but did restore dMLN IL-5 and IL-13 secretion. Thus natural Tregs can control AAI in an IL-10 independent manner.

The inhibitory cytokine IL-35 contributes to regulatory T-cell function

Regulatory T (T(reg)) cells are a critical sub-population of CD4+ T cells that are essential for maintaining self tolerance and preventing autoimmunity, for limiting chronic inflammatory diseases, such as asthma and inflammatory bowel disease, and for regulating homeostatic lymphocyte expansion. However, they also suppress natural immune responses to parasites and viruses as well as anti-tumour immunity induced by therapeutic vaccines. Although the manipulation of T(reg) function is an important goal of immunotherapy, the molecules that mediate their suppressive activity remain largely unknown. Here we demonstrate that Epstein-Barr-virus-induced gene 3 (Ebi3, which encodes IL-27beta) and interleukin-12 alpha (Il12a, which encodes IL-12alpha/p35) are highly expressed by mouse Foxp3+ (forkhead box P3) T(reg) cells but not by resting or activated effector CD4+ T (T(eff)) cells, and that an Ebi3-IL-12alpha heterodimer is constitutively secreted by T(reg) but not T(eff) cells. Both Ebi3 and Il12a messenger RNA are markedly upregulated in T(reg) cells co-cultured with T(eff) cells, thereby boosting Ebi3 and IL-12alpha production in trans. T(reg)-cell restriction of this cytokine occurs because Ebi3 is a downstream target of Foxp3, a transcription factor that is required for T(reg)-cell development and function. Ebi3-/- and Il12a-/- T(reg) cells have significantly reduced regulatory activity in vitro and fail to control homeostatic proliferation and to cure inflammatory bowel disease in vivo. Because these phenotypic characteristics are distinct from those of other IL-12 family members, this novel Ebi3-IL-12alpha heterodimeric cytokine has been designated interleukin-35 (IL-35). Ectopic expression of IL-35 confers regulatory activity on naive T cells, whereas recombinant IL-35 suppresses T-cell proliferation. Taken together, these data identify IL-35 as a novel inhibitory cytokine that may be specifically produced by T(reg) cells and is required for maximal suppressive activity.

Cloning of feline FOXP3 and detection of expression in CD4+CD25+ regulatory T cells

Regulatory T cells (Treg) are increased and directly infected by feline immunodeficiency virus (FIV) and likely play a role in other feline autoimmune, neoplastic, and infectious diseases. Phenotypically, Treg are best characterized by surface expression of CD4 and CD25 and intranuclear expression of the forkhead transcription factor Foxp3. Our objective was to clone and sequence feline FOXP3 for the purpose of developing assays to enhance studies of feline Treg. We determined the feline FOXP3 is 1293 nucleotides in length and codes for a protein that shares high homology to other species. A splice variant devoid of exon 2 was also identified. A real-time PCR assay was developed and used to show Foxp3 mRNA expression occurs primarily in CD4+CD25+ T cells. Two cross-reacting antibodies were identified by immunocytochemical staining of HEK293 cells transfected with feline FOXP3. The antibody labeling confirmed the nuclear localization of the protein. A flow cytometric assay was also validated and used to correlate the phenotypic and functional characteristics of feline Treg induced by treatment of lymph node lymphocytes with flagellin or LPS in combination with mitogen or IL2. Together, these studies provide useful tools to further investigate Foxp3 and Tregs in cats.

Allergen-induced CD11b+ CD11c(int) CCR3+ macrophages in the lung promote eosinophilic airway inflammation in a mouse asthma model

Although the recruitment of macrophages to the lung is a central feature of airway inflammation, its function in ongoing T(h)2 cell-mediated eosinophilic airway inflammation remains controversial. Here, we have demonstrated that the allergen-induced CD11b(+) CD11c(int) macrophage expressing CC chemokine receptor 3 (CCR3) in the lung performs a crucial function in the induction of eosinophilic asthma in a murine model. In the lungs of normal mice, residential cells evidencing high granularity phenotypically evidenced CD11b(int) CD11c(+) or CD11b(+) CD11c(int) cells, appearing at a 2:1 ratio. After allergen challenge, however, this reverses dramatically, up to a ratio of one to six. Approximately 91% of increased CD11b(+) CD11c(int) cells evidenced the expression of the CCR3 eotaxin receptor, but not other chemokine receptors, such as CCR5 and CXCR4. Interestingly, the CD11b(+) CD11c(int) cells purified from the lungs of OVA (ovalbumin)-sensitized and challenged mice evidenced higher antigen-presenting activity than was observed in CD11b(int) CD11c(+) cells. In order to investigate the in vivo function of CD11b(+) CD11c(int) cells, the cells were isolated from the lungs of OVA-sensitized and challenged mice and then adoptively transferred prior to the allergen challenge of normal mice. In the CD11b(+) CD11c(int)-transferred mice airway hyperresponsiveness, eosinophilic inflammation in the lung and T(h)2 cytokine secretion in the bronchoalveolar lavage fluids were significantly enhanced as the result of OVA challenge, as compared with the mice that received OVA-primed CD90(+) T cells or CD11b(int) CD11c(+) cells. These findings show that CD11b(+) CD11c(int) macrophages expressing CCR3 as key pro-inflammatory cells are both necessary and sufficient for allergen-specific T cell stimulation during ongoing eosinophilic airway inflammation.

Regulatory T cells in health and disease

The healthy host does not normally develop tissue destructive autoimmunity in part because of the presence of natural regulatory T cells. These cells are best identified by their expression of a unique transcription factor forkhead box transcription factor (Foxp3) that controls their regulatory function. Several other types of regulatory T cells also occur most of which are induced in response to antigen stimulation. Some of these express the Foxp3 transcription factor but many do not. The role of natural T-regulatory cells as well as induceable regulatory cells in autoimmunity, cancer, allergy and infectious disease is described. The current status of therapeutic approaches that modulate regulatory T-cell responses on the outcome of experimental animal and human disease is also discussed.

The impact of sex and sex hormones on lung physiology and disease: lessons from animal studies

Numerous animal studies have revealed significant effects of sex and sex hormones on normal lung development, lung physiology, and various lung diseases. The primary goal of this review is to summarize knowledge to date on the effects of sex and sex hormones on lung development, physiology, and disease in animals. Specific emphasis will be placed on fibrosis, allergic airway disease, acute lung injury models, respiratory infection, and lung toxicology studies.

The levels of CD4+CD25+ regulatory T cells in paediatric patients with allergic rhinitis and bronchial asthma

Our purpose was to determine whether numbers of CD4(+)CD25(+) T [T regulatory (T(reg))] cells and mRNA expression of functional molecules of T(reg) are related to airway allergy and disease severity in 51 paediatric patients with allergic rhinitis or bronchial asthma and 47 healthy controls. Surface markers were evaluated with flow cytometry, and mRNA was determined with real-time polymerase chain reaction. Children with allergic disease had fewer CD4(+)CD25(+) T cells (8 x 49% +/- 2 x 41% versus 9 x 58% +/- 2 x 43%, P<0 x 05) and CD4(+)CD25(hi) T cells (1 x 32% +/- 0 x 68% versus 1 x 70% +/- 0 x 68%, P<0 x 01) than control subjects. Numbers of CD4(+)CD25(+) and CD4(+)CD25(hi) T lymphocytes were higher in children with persistent allergic rhinitis and/or moderate-severe bronchial asthma than in those with respective milder disease. The number of T(reg) cells was correlated positively with total immunoglobulin E level. The mRNA expression of forkhead box P3 (FoxP3) was increased in moderate-severe versus mild asthma (2 x 93 +/- 0 x 38 versus 1 x 60 +/- 0 x 31, P< 0 x 01). Patients with moderate-severe bronchial asthma also had increased mRNA expression of interleukin (IL)-10 compared with patients with mild asthma (15 x 24 +/- 4 x 07 versus 3 x 77 +/- 2 x 18, P<0 x 01). The suppressive function of T(reg) cells from patients with more severe asthma was competent in vitro. On average, decreased numbers of T(reg) cells in children with allergic airway disease might represent a defect of the T(reg) population. With increased expression of FoxP3 and IL-10 in T(reg) from patients with relatively severe allergic disease, adaptive and functional T(reg) might be generated in response to aggravated atopy and disease severity.

Epidemiological and immunological evidence for the hygiene hypothesis

Allergic diseases are inflammatory disorders that develop on the basis of complex gene-environment interactions. The prevalence of allergies is steadily increasing and seems to be associated with modern lifestyle. Therefore, it was hypothesized that high living standards and hygienic conditions are correlated with an increased risk for the development of an allergic disease. This so-called "hygiene hypothesis" states that due to reduced exposure to microbial components, the proposed allergy-preventing potential of these factors is no more present in sufficient qualities and/or quantities, which leads to an imbalance of the immune system with a predisposition to the development of allergic disorders. Meanwhile, several epidemiological studies were conducted supporting this concept and generating novel ideas for the underlying mechanisms that were then followed up by use of well-defined animal models and human studies. The current view of cellular and molecular mechanisms responsible for these phenomena includes changes in the fine balancing of T helper cell 1 (Th1), Th2 and regulatory T cell (Treg) responses which are triggered by altered or missing innate immune cell activation. In fact, proper activation of cells of the innate immune system via their so-called pattern recognition receptors has been demonstrated to play a crucial role in early shaping of the immune system and suppression of the development of Th2-driven allergic immune responses. These processes start already in utero and prenatal as well as early postnatal developmental stages seem to represent a certain "window of opportunity" for allergy-preventing environmental influences.

Immunological principles of T-cell-mediated adverse drug reactions in skin

Drug hypersensitivity reactions in skin are an immune-mediated phenomenon associated with significant patient mortality and morbidity. Antigen-specific T cells, which have been isolated from the peripheral circulation and target organs of hypersensitive patients, are thought to propagate and regulate the development of clinical symptoms. The investigation of clinical cases with respect to the basic cellular and chemical mechanisms that underpin drug hypersensitivity has resulted in: i) the need to redress some aspects of present immunological dogma; and ii) additional fundamental immunological questions. Thus, the aim of this review article is to summarise present opinion on how and why drugs initiate a pathogenic T-cell response in a small section of the population and subsequently reflect on gaps in basic immunology and where future research might lead.