Indoleamine 2, 3-dioxygenase 1 mediated alterations in the functionality of immune cells, deciphers the pregnancy outcomes in crossbred dairy cows

Pregnancy establishment in bovines requires maternal immune cell modulation. Present study investigated possible role of immunosuppressive indolamine-2, 3-dioxygenase 1 (IDO1) enzyme in the alteration of neutrophil (NEUT) and peripheral blood mononuclear cells (PBMCs) functionality of crossbred cows. Blood was collected from non-pregnant (NP) and pregnant (P) cows, followed by isolation of NEUT and PBMCs. Plasma pro-inflammatory (IFNγ and TNFα) and anti-inflammatory cytokines (IL-4 and IL-10) were estimated by ELISA and analysis of IDO1 gene in NEUT and PBMCs by RT-qPCR. Neutrophil functionality was assessed by chemotaxis, measuring activity of myeloperoxidase and β-D glucuronidase enzyme and evaluating nitric oxide production. Changes in PBMCs functionality was determined by transcriptional expression of pro-inflammatory (IFNγ, TNFα) and anti-inflammatory cytokine (IL-4, IL-10, TGFβ1) genes. Significantly elevated (P < 0.05) anti-inflammatory cytokines, increased IDO1 expression, reduced NEUT velocity, MPO activity and NO production observed only in P cows. Significantly higher (P < 0.05) expression of anti-inflammatory cytokines and TNFα genes were observed in PBMCs. Study highlights possible role of IDO1 in modulating the immune cell and cytokine activity during early pregnancy and may be targeted as early pregnancy biomarkers.

Protective efficacy of Toxoplasma gondii bivalent MAG1 and SAG1 DNA vaccine against acute toxoplasmosis in BALB/c mice

Toxoplasma gondii can infect a wide range of warm-blooded animals, causing a global toxoplasmosis zoonotic epidemic. Surface antigen 1 (SAG1) protein is expressed at the proliferative tachyzoite stage, whereas matrix antigen 1 (MAG1) is expressed at the bradyzoite and tachyzoite stages. These two proteins were found to perform protective roles in previous studies; however, their synergetic protective efficacy as a DNA vaccine against toxoplasmosis has not been clarified. In this study, we constructed recombinant pcDNA3.1( +)-TgMAG1 (pMAG1), pcDNA3.1( +)-TgSAG1 (pSAG1), and pcDNA3.1( +)-TgMAG1-TgSAG1 (pMAG1-SAG1) plasmids and administered them intramuscularly to immunize mice. The levels of anti-T. gondii IgG in serum and cytokines, such as Interleukin (IL)-4, IL-10, and Interferon (IFN)-γ, in splenocytes were measured using ELISA and the respective culture supernatants. Lethal doses of T. gondii (type I) RH strain tachyzoites were administered to immunized mice, and mortality was assessed. Conversely, mice infected with low doses of tachyzoites were monitored to determine their survival rates, and parasite burden analyses of the brains and livers were conducted. The bivalent TgMAG1 and TgSAG1 DNA vaccines exhibited excellent protective immunity against toxoplasmosis in mice, with higher serum IgG and splenocyte IFN-γ release levels, longer survival days, and reduced parasite burden in the brain and liver tissues (p < 0.05). These findings provide a new perspective for the development of T. gondii vaccines.

Treatment with Helicobacter pylori-derived VacA attenuates allergic airway disease

Background

Asthma is an incurable heterogeneous disease with variations in clinical and underlying immunological phenotype. New approaches could help to support existing therapy concepts. Neonatal infection of mice with Helicobacter pylori or administration of H. pylori-derived extracts or molecules after birth have been shown to prevent the development of allergic airway disease later in life. This study evaluated the potential therapeutic efficacy of H. pylori vacuolating cytotoxin A (VacA) in allergic airway inflammation and investigated the underlying immunological mechanisms for its actions.

Methods

Murine models of allergic airway diseases, and murine and human in vitro models were used.

Results

In both an acute model and a therapeutic house dust mite model of allergic airway disease, treatment with H. pylori-derived VacA reduced several asthma hallmarks, including airway hyperresponsiveness, inflammation and goblet cell metaplasia. Flow cytometry and ELISA analyses revealed induction of tolerogenic dendritic cells (DC) and FoxP3 positive regulatory T cells (Tregs), and a shift in the composition of allergen-specific immunoglobulins. Depletion of Tregs during treatment with VacA reversed treatment-mediated suppression of allergic airway disease. Human monocyte derived DCs (moDC) that were exposed to VacA induced Tregs in co-cultured naïve autologous T cells, replicating key observations made in vivo.

Conclusion

H. pylori-derived VacA suppressed allergic airway inflammation via induction of Tregs in both allergic airway disease models. These data suggest that the immunomodulatory activity of VacA could potentially be exploited for the prevention and treatment of allergic airway disease.

Effect of ozone on allergic airway inflammation

Background

Exposure to ozone (O₃) is associated with increased risk of exacerbations of asthma, but the underlying mechanisms are not well studied.

Objective

We sought to determine whether O₃ exposure would enhance airway inflammatory responses to allergen and the GSTM1-null genotype would modulate this enhancement.

Methods

In a crossover design, 10 asthmatic participants (5 with GSTM1-null genotype) who had specific sensitization to Dermatophagoides pteronyssinus (DP) were exposed to 160 ppb O₃ or filtered air (FA) control for 4 hours on 2 separate days at least 3 weeks apart. At 20 hours after exposure, endobronchial challenge with DP allergen, and sham normal saline (NS) instillation, were performed in separate bronchi. Six hours later, a second bronchoscopy was performed to collect bronchoalveolar lavage (BAL) from the DP- and NS-challenged segments for analyses of inflammatory biomarkers. Linear regression compared cell and cytokine responses across the 4 exposure groups (FA-NS, O₃-NS, FA-DP, O₃-DP). Effect modification by GSTM1 genotype was assessed in stratified regressions.

Results

BAL eosinophil counts were increased in segments challenged with DP compared to sham-challenged segments (P < .01). DP challenge compared to sham also caused a significant increase in BAL concentrations of the T_H2 cytokines IL-4, IL-5, IL-10, and IL-13 (P < .03 for all comparisons). O₃ exposure did not significantly affect BAL cells or cytokine after DP challenge. Compared to GSTM1-present participants, GSTM1-null participants had significantly lower eosinophil (P < .041) and IL-4 (P < .014) responses to DP challenge after O₃ exposure.

Conclusions

While O₃ did not cause a clear differential effect on airway inflammatory responses to allergen challenge, those responses did appear to be modulated by the antioxidant enzyme, GSTM1.

Innate Immune Responses by Respiratory Viruses, Including Rhinovirus, During Asthma Exacerbation

Viral infection, especially with rhinovirus (RV), is a major cause of asthma exacerbation. The production of anti-viral cytokines such as interferon (IFN)-β and IFN-α from epithelial cells or dendritic cells is lower in patients with asthma or those with high IgE, which can contribute to viral-induced exacerbated disease in these patients. As for virus-related factors, RV species C (RV-C) induces more exacerbated disease than other RVs, including RV-B. Neutrophils activated by viral infection can induce eosinophilic airway inflammation through different mechanisms. Furthermore, virus-induced or virus-related proteins can directly activate eosinophils. For example, CXCL10, which is upregulated during viral infection, activates eosinophils in vitro. The role of innate immune responses, especially type-2 innate lymphoid cells (ILC2) and epithelial cell-related cytokines including IL-33, IL-25, and thymic stromal lymphopoietin (TSLP), in the development of viral-induced airway inflammation has recently been established. For example, RV infection induces the expression of IL-33 or IL-25, or increases the ratio of ILC2 in the asthmatic airway, which is correlated with the severity of exacerbation. A mouse model has further demonstrated that virus-induced mucous metaplasia and ILC2 expansion are suppressed by antagonizing or deleting IL-33, IL-25, or TSLP. For treatment, IFNs including IFN-β suppress not only viral replication but also ILC2 activation in vitro. Agonists of toll-like receptor (TLR) 3 or 7 can induce IFNs, which can then suppress viral replication and ILC2 activation. Therefore, if delivered in the airway, IFNs or TLR agonists could become innovative treatments for virus-induced asthma exacerbation.

Possible impact of neutrophils on immune responses during early pregnancy in ruminants

The interaction between early embryo and maternal immune system for the establishment of pregnancy is the focus of several studies; however, it remains unclear. The maternal immune response needs to keep a balance between avoiding any damage to the conceptus and maintaining its function in combating microbes as well. When conceptus-maternal crosstalk cannot achieve this balance, pregnancy losses might occur. Intercommunication between mother and conceptus is fundamental during early pregnancy to dictate the outcome of pregnancy. In ruminants, the embryo reacts with the maternal system mainly via interferon tau (IFNT) release. IFNT can act locally on the embryo and endometrial cells and systemically in several tissues and cells to regulate their response via the expression of interferon-stimulated genes (ISGs). Also, IFNT can induce the expression of inflammatory-related genes in immune cells. Day 7 embryo induces a shift in the maternal immune response towards anti-inflammatory (Th2) immune responses. During maternal recognition of pregnancy, peripheral mononuclear cells (PBMCs) and polymorphonuclear cells (PMNs) express markers that configure an anti-inflammatory response. However, PMNs response is more sensitive to the effects of IFNT. PMNs are more likely to express interferon-stimulated genes (ISGs), transforming growth factor-beta (TGFB), interleukin 10 (IL10), and arginase-1 (ARG1), configuring one of the most rapid immune responses to early pregnancy. This review focus on the local and peripheral immune responses during early pregnancy in ruminants, mainly the PMNs function in the immune system.

Adverse immunological responses against non-viral nanoparticle (NP) delivery systems in the lung

There is a large, unmet medical need to treat chronic obstructive pulmonary disease, asthma, idiopathic pulmonary fibrosis and other respiratory diseases. New modalities are being developed, including gene therapy which treats the disease at the DNA/RNA level. Despite recent innovations in non-viral gene therapy delivery for chronic respiratory diseases, unwanted or adverse interactions with immune cells, particularly macrophages, can limit drug efficacy. This review will examine the relationship between the design and fabrication of non-viral nucleic acid nanoparticle (NP) delivery systems and their ability to trigger unwanted immunogenic responses in lung tissues. NP formulated with peptides, lipids, synthetic and natural polymers provide a robust means of delivering the genetic cargos to the desired cells. However NP, or their components, may trigger local responses such as cell damage, edema, inflammation, and complement activation. These effects may be acute short-term reactions or chronic long-term effects like fibrosis, increased susceptibility to diseases, autoimmune disorders, and even cancer. This review examines the relationship between physicochemical properties, i.e. shape, charge, hydrophobicity, composition and stiffness, and interactions of NP with pulmonary immune cells. Inhalation is the ideal route of administration for direct delivery but inhaled NP encounter innate immune cells, such as alveolar macrophages (AM) and dendritic cells (DC), that perceive them as harmful foreign material, interfere with gene delivery to target cells, and can induce undesirable side effects. Recommendations for fabrication and formulation of gene therapies to avoid adverse immunological responses are given. These include fine tuning physicochemical properties, functionalization of the surface of NP to actively target diseased pulmonary cells and employing biomimetics to increase immunotolerance.

Regulation of Skin Barrier Function via Competition between AHR Axis versus IL-13/IL-4‒JAK‒STAT6/STAT3 Axis: Pathogenic and Therapeutic Implications in Atopic Dermatitis

Atopic dermatitis (AD) is characterized by skin inflammation, barrier dysfunction, and chronic pruritus. As the anti-interleukin-4 (IL-4) receptor α antibody dupilumab improves all three cardinal features of AD, the type 2 cytokines IL-4 and especially IL-13 have been indicated to have pathogenic significance in AD. Accumulating evidence has shown that the skin barrier function is regulated via competition between the aryl hydrocarbon receptor (AHR) axis (up-regulation of barrier) and the IL-13/IL-4‒JAK‒STAT6/STAT3 axis (down-regulation of barrier). This latter axis also induces oxidative stress, which exacerbates inflammation. Conventional and recently developed agents for treating AD such as steroid, calcineurin inhibitors, cyclosporine, dupilumab, and JAK inhibitors inhibit the IL-13/IL-4‒JAK‒STAT6/STAT3 axis, while older remedies such as coal tar and glyteer are antioxidative AHR agonists. In this article, I summarize the pathogenic and therapeutic implications of the IL-13/IL-4‒JAK‒STAT6/STAT3 axis and the AHR axis in AD.

Characterization of amoxicillin and clavulanic acid specific T-cell clones from patients with immediate drug hypersensitivity

BACKGROUND

Betalactam (BL) antibiotics are the most common cause of drug hypersensitivity. Amoxicillin (AX), which is often prescribed alongside clavulanic acid (Clav), is the most common elicitor. The aim of this study was to determine whether AX and Clav-responsive T-cells are detectable in patients with immediate hypersensitivity to AX-Clav, to assess whether these T-cells display the same specificity as that detected in skin and provocation testing, and to explore T-cell activation pathways.

METHODS

Drug-specific T-cell clones were generated from immediate hypersensitive patients´ blood by serial dilution and repetitive mitogen stimulation. Antigen specificity was assessed by measurement of proliferation and cytokine release. CD4+ /CD8+ phenotype and chemokine receptor expression were analyzed by flow cytometry.

RESULTS

110 AX-specific and 96 Clav-specific T-cell clones were generated from seven patients with positive skin test to either AX or Clav. Proliferation of AX- and Clav-specific clones was dose-dependent, and no cross-reactivity was observed. AX- and Clav-specific clones required antigen-presenting cells to proliferate, and drugs were presented to CD4+ and CD8+ T-cells by MHC class-II and I, respectively. A higher secretion of IL-13 and IL-5 was detected in presence of the culprit drug compared with the alternative drug. Clones expressed CD69, CCR4, CXCR3, and CCR10.

CONCLUSIONS

Our study details the antigen specificity and phenotype of T-cell clones generated from patients with AX-Clav-induced immediate hypersensitivity diagnosed by positive skin test. AX- and Clav-specific clones were generated from patients irrespective of whether AX or Clav was the culprit, although differences in cytokine secretion were observed.

Differential expression of T helper cytokines in the liver during early pregnancy in sheep

Liver plays important roles in the innate and adaptive immunity, and contributes to the maternal immune adjustments during pregnancy in mice and rats. T helper 1 (Th1) and Th2 cytokines are related to immune response. However, expression of Th1 and Th2 cytokines in maternal livers is unclear during early pregnancy in sheep. In this study, livers were collected on day 16 of the estrous cycle and on days 13, 16 and 25 of pregnancy (n = 6 for each group) in ewes, and qRT-PCR, western blot and immunohistochemistry were used to analyze the expression of Th1 and Th2 cytokines in the livers. Our results showed that interferon-gamma (IFN-γ), interleukin (IL)-2, IL-4, IL-6 and IL-10 were downregulated, and IL-5 was upregulated in the livers during early pregnancy. Furthermore, there was no effect for early pregnancy on expression of TNF-β in the livers, and the IFN-γ protein was limited to the endothelial cells of the proper hepatic arteries and portal veins. In conclusion, early pregnancy exerted its effect on the liver to regulate the Th cytokines expression, but there was no evident shift from Th1 to Th2 cytokines, which may be necessary for the maternal hepatic immune adjustments during early pregnancy in sheep.

Overexpression of Notch ligand Delta-like-1 by dendritic cells enhances their immunoregulatory capacity and exerts antiallergic effects on Th2-mediated allergic asthma in mice

Dendritic cells (DCs) are professional antigen-presenting cells, and Notch ligand Delta-like-1 (DLL1) on DCs was implicated in type 1T helper (Th1) differentiation. In this study, we produced genetically engineered bone marrow-derived DCs that expressed DLL1 (DLL1-DCs) by adenoviral transduction. DLL1-DCs exerted a fully mature phenotype, and had positive effects on expression levels of interleukin (IL)-12 and costimulatory molecules. Coculture of allogeneic T cells with ovalbumin (OVA)-pulsed DLL1-DCs enhanced T cell proliferative responses and promoted Th1 cell differentiation. Furthermore, adoptive transfer of OVA-stimulated DLL1-DCs into asthmatic mice alleviated the cardinal features of allergic asthma, including immunoglobulin E (IgE) production, airway hyperresponsiveness (AHR), airway inflammation, and production of Th2-type cytokines. Notably, enhanced levels of the Th1-biased IgG_2a response and interferon (IFN)-γ production were observed in these mice. Taken together, these data indicate that DLL1-DCs promoted Th1 cell development to alter the Th1/Th2 ratio and ameliorate Th2-mediated allergic asthma in mice.

Blomia tropicalis allergen 5 (Blo t 5) T-cell epitopes and their ability to suppress the allergic immune response

Blomia tropicalis is the major asthma allergen in the tropics comparable to Dermatophagoides pteronyssinus. However, little is known about the B. tropicalis epitopes recognized by T cells. Our aim was to identify the T-cell epitopes in the major B. tropicalis allergen, Blo t 5, and investigate the potential of the corresponding peptides to inhibit the allergic inflammatory lung response. C57BL/6 mice were immunized with plasmid DNA encoding Blo t 5 and T-cell epitopes identified using the interferon-γ ELISPOT assay with 15-mer overlapping peptides. C57BL/6 mice were sensitized with bone-marrow-derived dendritic cells (BMDC) pulsed with Blo t 5 allergen followed by intranasal Blo t 5 challenge. Two H-2^b restricted epitopes (Bt5_76-90 and Bt5_106-115 ) were recognized by CD4 T cells specific for Blo t 5, but no CD8 epitopes were identified. In mice sensitized with Blo t 5-pulsed BMDC and challenged with intranasal Blo t 5 Bt5_76-90 and Bt5_106-115 , peptide-specific CD4 T cells were found to secrete the T helper type 2 cytokines interleukin-5 and interleukin-13. Intradermal administration of synthetic peptides encoding the identified T-cell epitopes suppressed allergic airway inflammation to further allergen challenges. Hence, we have identified novel CD4 T-cell epitopes specific for Blo t 5 and demonstrated that these peptides could be employed therapeutically to suppress the T-cell response in a murine model of allergic airway inflammation.

Dose-dependent immunomodulating effects of endotoxin in allergic airway inflammation

How very high exposure levels to endotoxin in a farming environment provide protection against respiratory allergic symptoms and low-to-moderate levels of endotoxin in urban homes promote allergic response is unclear. Dose-specific bacterial endotoxin or LPS-induced tolerance mechanisms can affect lung inflammations, coupled with the Th2 immune responses. Here, we explored the effects of intranasal exposure of LPS at two different doses (based on occupational exposures during handling of agricultural wastes) in OVA-sensitized allergic wild type (WT) and TLR4-KO mice, particularly, with respect to Th2 cytokines and Tregs level. Low-dose LPS (100 ng) exposure prohibited airway tolerance and failed to generate T-cell-dependent protection against lung inflammations in allergic mice. Furthermore, low Tregs at the inflammatory site and induced Th2 cytokines, as well as IL-6 and IL-25, suggested that low-dose LPS might be associated with the suppression of tolerance mechanisms. In contrast, high-dose LPS (20 µg) favored the suppression of Th2 cytokines, IL-6 and IL-25, but failed to induce Th1 cytokines (e.g. IFN-γ). Our results suggest that low-dose LPS can enhance airway allergic inflammation through failing of antigen-dependent immune regulatory homeostasis. The exposure levels of LPS can determine the generation of inflammatory responses in airway allergy.

Suppression of MUC5AC expression in human bronchial epithelial cells by interferon-γ

BACKGROUND

Excessive mucin secretion in the airway is an important feature of airway inflammatory diseases. MUC5AC expression is regulated by a variety of stimuli such as cytokines. Little is known about the role of interferon (IFN)-γ in MUC5AC expression in human bronchial epithelial cells.

METHODS

Human pulmonary mucoepidermoid carcinoma cell line (NCI-H292) and normal human bronchial epithelial (NHBE) cells were used to assess the effects of IFN-γ on MUC5AC transcription.

RESULTS

Transforming growth factor (TGF)-α and double-stranded RNA (polyI:C)-induced MUC5AC mRNA and protein expression was repressed by IFN-γ in a concentration-dependent manner. IFN-γ showed limited effects on TGF-α and polyI:C-induced activation of epidermal growth factor receptor (EGFR) and extracellular signal-regulated kinase (ERK). A chromatin immunoprecipitation assay indicated that Sp1 bound to its cognate sequence located on the MUC5AC promoter. The Sp1 inhibitor mithramycin A inhibited MUC5AC mRNA expression, implying a critical role for Sp1 in MUC5AC induction. Importantly, IFN-γ impeded Sp1 binding to the MUC5AC promoter.

CONCLUSIONS

These results suggest that IFN-γ represses MUC5AC expression, disturbing binding of Sp1 to its target sequences.

Is a high-fiber diet able to influence ovalbumin-induced allergic airway inflammation in a mouse model?

Background:

More recently, a large amount of experimental and clinical discovered that dietary- fiber intake would decrease the susceptibility to allergic airway disease (AAD) and respiratory inflammation.

Objective:

To investigate whether a fiber-intake supplement is able to influence the induction of AAD and to elucidate the interactive relationship.

Methods:

AAD model mice and control mice were raised on a fundamental diet with standard 4% fiber content, whereas other mice were fed a 10% fiber-content diet in the high fiber-content group, along with a 25% fiber-content diet instead in very-high fiber-content group. All experimental mice were sensitized and challenged with ovalbumin to induce allergic inflammation in both the upper and lower airways. Hallmarks of AAD were examined in terms of eosinophil infiltration and goblet cell metaplasia in subepithelial mucosa, T-helper type 1 (Th1) to Th2 skewing of the immune response. Furthermore, to elucidate the interrelations, we generated 16S ribosomal DNA from fecal samples and further validated the variation of colony composition in each group.

Results:

The excessive high-fiber supplement induced a promoting effect rather than a suppressive effect, including a rise in nasal rubbing and sneezing, an increase in eosinophil inflammation and goblet cell metaplasia in subepithelial mucosa, and promoted Th2 skewing of the immune response as well as the production of serum levels of ovalbumin-specific immunoglobulin E. Moreover, overconsumption of dietary fiber greatly altered the construction of bacterial flora in the intestinal tract, including an increased proportion of Firmicutes, Actinobacteria, and Proteobacteria, and a decreased proportion of Bacteroidetes.

Conclusion:

Our work indicated that, instead of a protecting impact, excessive fiber intake preformed a negative influence on the induction of AAD. Therefore, we suspected that an excessive supplement of dietary fiber might not be an advisable method for the prevention and treatment of AADs.

The RNA Binding Protein Mex-3B Is Required for IL-33 Induction in the Development of Allergic Airway Inflammation

Allergic airway inflammation is one of the primary features of allergic asthma. Interleukin-33 (IL-33) is recognized as a key pro-inflammatory cytokine that mediates allergic airway inflammation, and its expression is elevated in this condition, but little is known about the regulatory mechanisms underlying IL-33 induction. Here, we show that the RNA binding protein Mex-3B plays a critical role in the induction of IL-33 in the development of allergic airway inflammation. We generated Mex3b(-/-) mice and found that they develop significantly less airway inflammation than wild-type mice due to reduced induction of IL-33. Furthermore, we show that Mex-3B directly upregulates IL-33 expression by inhibiting miR-487b-3p-mediated repression of IL-33. Moreover, we show that inhalation of an antisense oligonucleotide targeting Mex-3B suppresses allergic airway inflammation. Our data identify a signaling pathway that post-transcriptionally regulates IL-33 expression and suggest that Mex-3B could be a promising molecular target for the treatment of allergic asthma.

Regulatory CD4+CD25+ T Cells Dampen Inflammatory Disease in Murine Mycoplasma Pneumonia and Promote IL-17 and IFN-γ Responses

Mycoplasmas cause respiratory diseases characterized by persistent infection and chronic airway inflammation. Mycoplasma lung disease is immunopathologic, with CD4⁺ Th cells determining both disease severity and resistance to infection. Th2 cell responses promote immunopathology, while Th1 cells confer resistance to infection. However, regulatory CD4⁺ T cells may also have a role in the pathogenesis of mycoplasma respiratory diseases. We hypothesized Treg cells control the severity of the inflammatory lesions and may also promote persistence of infection. To examine this, BALB/c mice were depleted of CD25⁺ cells, and had increased disease severity due to Mycoplasma pulmonis infection. Increases in mycoplasma antibody responses and lymphocyte infiltration into lungs also occurred after CD25⁺ cell depletion. CD4⁺CD25⁺ regulatory T cells promoted IFN-γ and IL-17 mycoplasma-specific CD4⁺ T cell responses in vitro and in vivo, while dampening IL-13⁺ Th responses. Neither IL-10 nor TGF-ß expression was detected in CD4⁺CD25⁺ T cells from lymph nodes. Thus, a regulatory T cell population plays an important role in controlling damaging immune responses in mycoplasma respiratory disease but does not contribute to persistence of infection. It appears that a regulatory T cell population preferentially dampens Th2 cell-mediated inflammatory responses to mycoplasma through a mechanism independent of IL-10 or TGF-ß characteristic of “classic” Treg cells.

A novel mannoside-glycocluster adjuvant: Compared in vitro to CpG ODN and MPL and tested in vivo in mouse asthma model

BACKGROUND

Allergen-specific immunotherapy balances the Th2-biased immunity towards Th1 and Treg responses. Adjuvants are used in allergen preparations to intensify the immune responses. The increased prevalence of allergies in developed societies has been associated with decreased microbial load during childhood. This has initiated a search for microbial structures to be used as adjuvants. Our study has shown that a synthetic triacedimannose (TADM) may suppress the Th2-type allergic inflammatory response. The aim of this study was to compare the properties of TADM with capacities of other adjuvants, CpG ODN and MPL, to modulate cytokine production in PBMC and regulate sensitisation in an OVA-sensitised mouse asthma model.

METHODS

The effects of TADM were studied in vitro on birch stimulated PBMC cultures of birch allergic rhinitis patients with other known adjuvants. Cytokines in supernatants were measured by Luminex. Effects of TADM were analysed in vivo in a mouse model of OVA-induced allergic asthma by analysing BAL, cytokine mRNA and serum antibodies.

RESULTS

TADM was the only adjuvant that significantly suppressed the production of all birch induced Th2-type cytokines. In a murine model, TADM significantly suppressed the specific IgE production and enhanced IFN-γ production.

CONCLUSIONS

TADM suppresses the birch allergen induced Th2-type cytokine responses in allergic subjects more efficiently than the two other adjuvants, MPL and CpG ODN. TADM is immunomodulatory also in vivo and decreases the IgE levels and increases the IFN-γ responses in a murine model. These results suggest that TADM may be a promising candidate for novel adjuvants in immunotherapy.

Ferulic Acid Induces Th1 Responses by Modulating the Function of Dendritic Cells and Ameliorates Th2-Mediated Allergic Airway Inflammation in Mice

This study investigated the immunomodulatory effects of ferulic acid (FA) on antigen-presenting dendritic cells (DCs) in vitro and its antiallergic effects against ovalbumin- (OVA-) induced Th2-mediated allergic asthma in mice. The activation of FA-treated bone marrow-derived DCs by lipopolysaccharide (LPS) stimulation induced a high level of interleukin- (IL-) 12 but reduced the expression levels of the proinflammatory cytokines IL-1β, IL-6, and tumor necrosis factor- (TNF-) α. Compared to control-treated DCs, FA significantly enhanced the expressions of Notch ligand Delta-like 4 (Dll4), MHC class II, and CD40 molecules by these DCs. Furthermore, these FA-treated DCs enhanced T-cell proliferation and Th1 cell polarization. In animal experiments, oral administration of FA reduced the levels of OVA-specific immunoglobulin E (IgE) and IgG₁ and enhanced IgG_2a antibody production in serum. It also ameliorated airway hyperresponsiveness and attenuated eosinophilic pulmonary infiltration in dose-dependent manners. In addition, FA treatment inhibited the production of eotaxin, Th2 cytokines (IL-4, IL-5, and IL-13), and proinflammatory cytokines but promoted the Th1 cytokine interferon- (IFN-) γ production in bronchoalveolar lavage fluid (BALF) and the culture supernatant of spleen cells. These findings suggest that FA exhibits an antiallergic effect via restoring Th1/Th2 imbalance by modulating DCs function in an asthmatic mouse model.

Potentiation of cytokine-induced proliferation of human Natural Killer cells by intravenous immunoglobulin G

Intravenous IgG (IVIG) therapy can be used for immunomodulation. IL-2 is an immunoregulatory cytokine. We evaluated IVIG modulation of human blood lymphocyte response to IL-2 and other cytokines. Neither IVIG nor low concentrations of IL-2 (3-30U/ml) induced lymphocyte proliferation, but in combination they synergistically enhanced proliferation of NK cells. The CD56(bright) cells expanded more than CD56(dim) NK cells, with 90% of NK cells dividing up to 8 generations by day 6, while <8% of T cells divided. IVIG also potentiated NK cell proliferation with IL-12, IL-15 and IL-18. The IVIG+cytokine-expanded NK cells were less cytotoxic for K562 cells, than NK cells with cytokine alone. IVIG also enhanced interferon-γ production with IL-2, IL-12 and IL-18. In conclusion, IVIG selectively potentiates NK cell proliferation and interferon-γ secretion with IL-2, IL-12, IL-15 and IL-18 in vitro. These findings warrant evaluation in vivo in relation to NK cells and the immunoregulatory actions of IVIG.

Requirement of MyD88 and Fas pathways for the efficacy of allergen-free immunotherapy

BACKGROUND

We have shown that mycobacterial antigens and CpG oligodeoxynucleotides downmodulate airway allergic inflammation by mechanisms dependent on T-cell activation. Here, we investigated the participation of the innate response, particularly the role of MyD88 adaptor, and Fas molecules in the effectiveness of DNA-HSP65 or CpG/culture filtrated proteins (CFP) immunotherapy.

METHODS

Mice sensitized and challenged with Der p 1 allergen were treated with DNA-HSP65, CpG/CFP, or with adoptively transferred cells from immunized mice. The treatment efficacy was assessed by evaluating eosinophil recruitment, antibody, and cytokine production.

RESULTS

In addition to downregulating the Th2 response, DNA-HSP65 and CpG/CFP promoted IL-10 and IFN-γ production. Adoptive transfer of cells from mice immunized with DNA-HSP65 or CpG/CFP to allergic recipients downmodulated the allergic response. Notably, transfer of cells from DNA-HSP65- or CpG/CFP-immunized MyD88(-/-) mice failed to reduce allergy. Additionally, for effective reduction of allergy by cells from CpG/CFP-immunized mice, Fas molecules were required. Although DNA-HSP65 or CpG/CFP immunization stimulated antigen-specific production of IFN-γ and IL-10, the effect of DNA-HSP65 was associated with IL-10 while CpG/CFP was associated with IFN-γ. Moreover, after stimulation with mycobacterial antigens plus Der p 1 allergen, cells from mite-allergic patients with asthma exhibited similar patterns of cytokine production as those found in the lung of treated mice.

CONCLUSIONS

This study provides new insights on the mechanisms of allergen-free immunotherapy by showing that both DNA-HSP65 and CpG/CFP downregulated house dust mite-induced allergic airway inflammation via distinct pathways that involve not only induction of mycobacterial-specific adaptive responses but also signaling via MyD88 and Fas molecules.

Cellular responses to Staphylococcus aureus alpha-toxin in chronic rhinosinusitis with nasal polyps

BACKGROUND

In contrast to Staphylococcus aureus-derived superantigenic exotoxins, the role of non-superantigenic exotoxins in the pathogenesis of eosinophilic airway diseases remains obscure. We sought to characterize S. aureus alpha-toxin-induced cellular responses in chronic rhinosinusitis with nasal polyps (CRSwNP).

METHODS

Dispersed nasal polyp cells and uncinate tissue cells were prepared from patients with CRS with and without nasal polyps, respectively. Cells were incubated with various concentrations of alpha-toxin or staphylococcal enterotoxin B and then the levels of IL-5, IL-13, IFN-γ, IL-17A, and IL-10 in the cell supernatants were determined. The pathophysiological significance of alpha-toxin-induced cytokine production was also determined including radiological severity of rhinosinusitis, tissue and blood eosinophilia, serum total IgE level, and 1-s forced expiratory volume/forced vital capacity ratio (FEV1/FVC).

RESULTS

Nasal polyp cells produced substantial amounts of IL-5, IL-13, IFN-γ, IL-17A, and IL-10 in response to alpha-toxin. Cytokine production was higher in nasal polyp cells than in uncinate tissue cells. The potency of alpha-toxin in stimulating IL-5, IL-13, and IL-10 production was comparable to that of enterotoxin. Alpha-toxin-induced IFN-γ, IL-17A, and IL-10 production significantly and negatively correlated with the degree of eosinophil infiltration into nasal polyps. Conversely, alpha-toxin-induced IFN-γ and IL-10 production significantly and positively correlated with FEV1/FVC. IL-10 production was significantly lower in asthmatic patients compared to non-asthmatics

CONCLUSIONS

S. aureus-derived alpha-toxin can provoke cellular responses in nasal polyps. These responses, especially failure to synthesize IL-10, may play a role in the pathophysiology of CRSwNP.

Epicutaneous immune modulation with Bet v 1 plus R848 suppresses allergic asthma in a murine model

BACKGROUND

Combining allergen(s) with an adjuvant is a strategy to improve the efficacy and safety of allergen-specific immunotherapy. Here, we aimed at investigating the adjuvant effects of polyadenylic-polyuridylic acid (poly(A:U)), a TLR3 agonist, and R848 (resiquimod), a TLR7 agonist, in epicutaneous immunotherapy with Bet v 1, the major birch pollen allergen, to intervene in birch pollen allergy.

METHODS AND RESULTS

BALB/c mice received epicutaneous immunization (EPI) with recombinant Bet v 1 (rBet v 1) alone, or plus poly(A:U), or R848 on their depilated back using patches. Among the groups, EPI with rBet v 1 and R848 induced detectable levels of IFN-γ-producing CD4(+) T cells in lymph nodes and Bet v 1-specific IgG2a antibodies in the sera of mice. Before or after EPI, mice were sensitized with rBet v 1 plus aluminium hydroxide adjuvant and intranasally challenged with birch pollen extract. Prophylactic EPI with rBet v 1 plus R848 inhibited the production of biologically active Bet v 1-specific IgE antibodies in sensitization. Prophylactic and therapeutic EPI with rBet v 1 plus R848 suppressed lung inflammation upon challenges. Remarkably, only rBet v 1 plus R848 reduced the development of enhanced pause (PenH), a substituted parameter for airway hyper-reactivity, in challenged mice. In contrast to R848, poly(A:U) did not present adjuvant effect on the suppression of asthmatic features.

CONCLUSION

Epicutaneous immunization with rBet v 1 plus R848 induced predominant Bet v 1-specific Th1 responses and efficiently suppressed asthmatic features elicited by birch pollen. R848 could be a promising adjuvant in epicutaneous immunotherapy for birch pollen-induced allergic asthma.

γδT cells suppress inflammation and disease during rhinovirus-induced asthma exacerbations

Most asthma exacerbations are triggered by virus infections, the majority being caused by human rhinoviruses (RV). In mouse models, γδT cells have been previously demonstrated to influence allergen-driven airways hyper-reactivity (AHR) and can have antiviral activity, implicating them as prime candidates in the pathogenesis of asthma exacerbations. To explore this, we have used human and mouse models of experimental RV-induced asthma exacerbations to examine γδT-cell responses and determine their role in the immune response and associated airways disease. In humans, airway γδT-cell numbers were increased in asthmatic vs. healthy control subjects during experimental infection. Airway and blood γδT-cell numbers were associated with increased airways obstruction and AHR. Airway γδT-cell number was also positively correlated with bronchoalveolar lavage (BAL) virus load and BAL eosinophils and lymphocytes during RV infection. Consistent with our observations of RV-induced asthma exacerbations in humans, infection of mice with allergic airways inflammation increased lung γδT-cell number and activation. Inhibiting γδT-cell responses using anti-γδTCR (anti-γδT-cell receptor) antibody treatment in the mouse asthma exacerbation model increased AHR and airway T helper type 2 cell recruitment and eosinophilia, providing evidence that γδT cells are negative regulators of airways inflammation and disease in RV-induced asthma exacerbations.

Alendronate attenuates eosinophilic airway inflammation associated with suppression of Th2 cytokines, Th17 cytokines, and eotaxin-2

Bisphosphonates (BPs) have been widely used to treat osteoporosis. They act by inhibiting farnesyl diphosphate synthase in the mevalonate pathway. This resembles the action of statins, whose immune-modulating effect has recently been highlighted. In contrast, the effect of BPs on immune responses has not been elucidated well. In this study, we examined the effect of alendronate (ALN), a nitrogen-containing BP, on allergic airway inflammation in a mouse model. BALB/c mice were sensitized twice with OVA and challenged three times with nebulized OVA to induce eosinophilic airway inflammation. ALN was administered by an intragastric tube before each inhalation. ALN strongly suppressed airway eosinophilia and Th2, as well as Th17 cytokine production in the lung. ALN also attenuated eotaxin-2 production in the lung. Immunohistochemistry demonstrated that the major cell source of eotaxin-2 was peribronchial/perivascular macrophages, and flow cytometrical studies confirmed that ALN decreased eotaxin-2 expression in these macrophages. Furthermore, ALN attenuated eotaxin-2 production from mouse pleural macrophages and human monocyte/macrophage-like THP-1 cells in vitro. These results suggest that ALN suppressed Ag-induced airway responses in the mouse model. The suppression of eotaxin-2 production from macrophages appears to be one of ALN's immunomodulatory effects, whereas the mechanism by which ALN suppressed Th2 and Th17 responses could not be fully elucidated in this study. Although a clinical study should be conducted, ALN could be a novel therapeutic option for asthma.

The effect of aerosol polyethylenimine/interferon-γ plasmid complexes on expression of inflammatory cytokines in mouse lung

BACKGROUND

The expression of inflammatory cytokines in lung tissue plays an important role in immune function of the lung. In this study, we tested whether aerosol delivery of the gene of interferon-γ (IFNγ) could affect inflammatory cytokine expression in mouse lung.

METHODS

Murine IFNγ-expressing plasmids (pcDNA-IFNγ) complexed with polyethylenimine (PEI) (PEI/pcDNA-IFNγ) were constructed, and their transfection efficiency was assessed in vivo using real-time quantitative RT-PCR and enzyme-linked immunosorbent assay. After aerosol administration of the plasmid complexes and confirmation of the IFNγ plasmid location in lung tissue, we measured mRNA levels of the inflammatory cytokines interleukin-1 (IL-1), IL-6, IL-10, tumor necrosis factor-α (TNF-α), and granulocyte-macrophage colony-stimulating factor (GM-CSF) on days 1 to 7 in mouse lung tissues using real-time RT-PCR.

RESULTS

IFNγ mRNA expression in mouse lung was significantly increased 24 hr after a single aerosol administration of PEI/pcDNA-IFNγ and gradually decreased over the next 5 days, whereas the mRNA expressions of IL-1, IL-6, and GM-CSF were markedly decreased, but not those of IL-10 and TNF-α.

CONCLUSIONS

PEI/IFNγ gene therapy delivered by aerosol has immune-regulating potential by suppressing lung cytokine mRNA expression, and therefore may alleviate lung disease.

Regulation of immunological balance by sustained interferon-γ gene transfer for acute phase of atopic dermatitis in mice

Interferon (IFN)-γ, a potent T helper 1 (Th1) cell cytokine, is suggested to suppress Th2 cell responses. Here, we aimed to investigate whether pCpG-Muγ, a plasmid continuously expressing murine IFN-γ, is an effective treatment of atopic dermatitis, a Th2-dominant skin disease. Nishiki-nezumi Cinnamon/Nagoya (NC/Nga) atopic mice with early dermatitis were transfected with pCpG-Muγ by a hydrodynamic tail vein injection at a dose of 0.05 or 0.2 pmol per mouse. The skin lesions improved only in mice receiving the high dose of pCpG-Muγ. IFN-γ gene transfer resulted in a high mRNA expression of IFN-γ and interleukin (IL)-12 and regulatory T cell (Treg) related cytokines, such as IL-10 and transforming growth factor-β, in the spleen, whereas it reduced the IL-4 mRNA expression, and serum levels of immunoglobulin (Ig) G1 and IgE. In addition, the gene transfer markedly inhibited the epidermal thickening, infiltration of inflammatory cells into the skin, the occurrence of dry skin and pruritus. No exacerbating effect on the Th1-mediated contact dermatitis was observed after IFN-γ gene transfer. Taken together, these results indicate that sustained IFN-γ gene transfer induced polarized Th1 immunity under Th2-dominant conditions in NC/Nga mice, leading to an improvement in the symptoms of acute atopic dermatitis without adverse side effects.

Activation of lymphocytes induced by bronchial epithelial cells with prolonged RSV infection

Respiratory syncytial virus (RSV) preferentially infects airway epithelial cells,which might be responsible for susceptibility to asthma; however, the underlying mechanism is not clear. This study determined the activation of lymphocytes and drift of helper T (Th) subsets induced by RSV-infected human bronchial epithelial cells (HBECs) in vitro. HBECs had prolonged infection with RSV, and lymphocytes isolated from human peripheral blood were co-cultured with RSV-infected HBECs. Four groups were established, as follows: lymphocytes (group L); lymphocytes infected with RSV (group RL); co-culture of lymphocytes with non-infected HBECs (group HL); and co-culture of lymphocytes with infected HBECs (group HRL). After co-culture with HBECs for 24 hours, lymphocytes were collected and the following were determined in the 4 groups: cell cycle status; apoptosis rate; and concentrations of IL-4, IFN-γ, and IL-17 in the supernatants. Cell cycle analysis for lymphocytes showed a significant increase in S phase cells, a decrease in G1 phase cells, and a higher apoptosis rate in group HRL compared with the other three groups. In group HRL, the levels of IL-4, IFN-γ, and IL-17 in supernatants were also higher than the other three groups. For further study, lymphocytes were individually treated with supernatants from non-infected and RSV-infected HBECs for 24 h. We showed that supernatants from RSV-infected HBECs induced the differentiation of Th2 and Th17 subsets, and suppressed the differentiation of Treg subsets. Our results showed that HBECs with prolonged RSV infection can induce lymphocyte proliferation and apoptosis, and enhance the release of cytokines by lymphocytes. Moreover, subset drift might be caused by RSV-infected HBECs.

High expression of IL-22 suppresses antigen-induced immune responses and eosinophilic airway inflammation via an IL-10-associated mechanism

Allergic inflammation in the airway is generally considered a Th2-type immune response. However, Th17-type immune responses also play important roles in this process, especially in the pathogenesis of severe asthma. IL-22 is a Th17-type cytokine and thus might play roles in the development of allergic airway inflammation. There is increasing evidence that IL-22 can act as a proinflammatory or anti-inflammatory cytokine depending on the inflammatory context. However, its role in Ag-induced immune responses is not well understood. This study examined whether IL-22 could suppress allergic airway inflammation and its mechanism of action. BALB/c mice were sensitized and challenged with OVA-Ag to induce airway inflammation. An IL-22-producing plasmid vector was delivered before the systemic sensitization or immediately before the airway challenge. Delivery of the IL-22 gene before sensitization, but not immediately before challenge, suppressed eosinophilic airway inflammation. IL-22 gene delivery suppressed Ag-induced proliferation and overall cytokine production in CD4(+) T cells, indicating that it could suppress Ag-induced T cell priming. Antagonism of IL-22 by IL-22-binding protein abolished IL-22-induced immune suppression, suggesting that IL-22 protein itself played an essential role. IL-22 gene delivery neither increased regulatory T cells nor suppressed dendritic cell functions. The suppression by IL-22 was abolished by deletion of the IL-10 gene or neutralization of the IL-10 protein. Finally, IL-22 gene delivery increased IL-10 production in draining lymph nodes. These findings suggested that IL-22 could have an immunosuppressive effect during the early stage of an immune response. Furthermore, IL-10 plays an important role in the immune suppression by IL-22.

Acinetobacter baumannii infection inhibits airway eosinophilia and lung pathology in a mouse model of allergic asthma

Allergic asthma is a dysregulation of the immune system which leads to the development of Th2 responses to innocuous antigens (allergens). Some infections and microbial components can re-direct the immune response toward the Th1 response, or induce regulatory T cells to suppress the Th2 response, thereby inhibiting the development of allergic asthma. Since Acinetobacter baumannii infection can modulate lung cellular and cytokine responses, we studied the effect of A. baumannii in modulating airway eosinophilia in a mouse model of allergic asthma. Ovalbumin (OVA)-sensitized mice were treated with live A. baumannii or phosphate buffered saline (PBS), then intranasally challenged with OVA. Compared to PBS, A. baumannii treatment significantly reduced pulmonary Th2 cytokine and chemokine responses to OVA challenge. More importantly, the airway inflammation in A. baumannii-treated mice was strongly suppressed, as seen by the significant reduction of the proportion and the total number of eosinophils in the bronchoalveolar lavage fluid. In addition, A. baumannii-treated mice diminished lung mucus overproduction and pathology. However, A. baumannii treatment did not significantly alter systemic immune responses to OVA. Serum OVA-specific IgE, IgG1 and IgG2a levels were comparable between A. baumannii- and PBS-treated mice, and tracheobronchial lymph node cells from both treatment groups produced similar levels of Th1 and Th2 cytokines in response to in vitro OVA stimulation. Moreover, it appears that TLR-4 and IFN-γ were not directly involved in the A. baumannii-induced suppression of airway eosinophilia. Our results suggest that A. baumannii inhibits allergic airway inflammation by direct suppression of local pulmonary Th2 cytokine responses to the allergen.

Distinct cytokine and regulatory T cell profile at pleural sites of dual HIV/tuberculosis infection compared to that in the systemic circulation

Pleural tuberculosis (TB) remains a common presentation of Mycobacterium tuberculosis (MTB) infection in HIV/TB dually infected subjects, and both cellular and acellular components of the pleural milieu promote HIV-1 replication; however, they remain uncharacterized. Using cytokine array of pleural fluid and real-time reverse transcription-polymerase chain reaction (RT-PCR) and immunophenotype analysis, pleural fluid mononuclear cells (PFMC) were compared to systemic counterparts [i.e. plasma and peripheral blood mononuclear cells (PBMC)]. Significant increases in pleural fluid cytokines compared to plasma were limited to interleukin (IL)-6, IL-8, interferon (IFN)-γ and transforming growth factor (TGF)-β, and did not include other T helper type 1 (Th1) (IL-2, IL-15), Th2 or Th17 cytokines. Patterns and levels of cytokines were indistinguishable between pleural fluid from HIV/TB and TB patients. Forkhead box P3 (FoxP3) mRNA in PFMC was increased significantly and correlated highly with levels of IL-6 and IL-8, less with TGF-β, and not with IFN-γ. Among CD4 T cells, FoxP3-reactive CD25(hi) were increased in HIV/TB dually infected subjects compared to their PBMC, and up to 15% of FoxP3(+) CD25(hi) CD4 T cells were positive for IL-8 by intracellular staining. These data implicate a dominant effect of MTB infection (compared to HIV-1) at pleural sites of dual HIV/TB infection on the local infectious milieu, that include IL-6, IL-8, IFN-γ and TGF-β and regulatory T cells (T(reg) ). A correlation in expansion of T(reg) with proinflammatory cytokines (IL-6 and IL-8) in pleural fluid was shown. T(reg) themselves may promote the inflammatory cytokine milieu through IL-8.

Dopamine D1-like receptor antagonist attenuates Th17-mediated immune response and ovalbumin antigen-induced neutrophilic airway inflammation

Allergic airway inflammation is generally considered a Th2-type immune response. Recent studies, however, demonstrated that Th17-type immune responses also play important roles in this process, especially in the pathogenesis of neutrophilic airway inflammation, a hallmark of severe asthma. We previously reported that dendritic cells release dopamine to naive CD4(+) T cells in Ag-specific cell-cell interaction, in turn inducing Th17 differentiation through dopamine D1-like receptor (D1-like-R). D1-like-R antagonist attenuates Th17-mediated diseases such as experimental autoimmune encephalomyelitis and autoimmune diabetes. However, the effect of antagonizing D1-like-R on Th17-mediated airway inflammation has yet to be studied. In this study, we examined whether D1-like-R antagonist suppresses OVA-induced neutrophilic airway inflammation in OVA TCR-transgenic DO11.10 mice and then elucidated the mechanism of action. DO11.10 mice were nebulized with OVA or PBS, and some mice received D1-like-R antagonist orally before OVA nebulization. D1-like-R antagonist significantly suppressed OVA-induced neutrophilic airway inflammation in DO11.10 mice. It also inhibited the production of IL-17 and infiltration of Th17 cells in the lung. Further, D1-like-R antagonist suppressed the production of IL-23 by lung CD11c(+) APCs. In contrast, D1-like-R antagonist did not increase Foxp3(+) regulatory T cells in the lung. D1-like-R antagonist neither suppressed nonspecific LPS-induced neutrophilic airway inflammation nor OVA-induced eosinophilic airway inflammation. These results indicate that D1-like-R antagonist could suppress Th17-mediated neutrophilic airway inflammation, raising the possibility that antagonizing D1-like-R serves as a promising new strategy for treating neutrophil-dominant severe asthma.

Ara h 1-reactive T cells in individuals with peanut allergy

BACKGROUND

Effective immunotherapy for peanut allergy is hampered by a lack of understanding of peanut-reactive CD4(+) T cells.

OBJECTIVE

To identify, characterize, and track Ara h 1-reactive cells in subjects with peanut allergy by using Ara h 1-specific class II tetramers.

METHODS

Tetramer-guided epitope mapping was used to identify the antigenic peptides within the peanut allergen Ara h 1. Subsequently, HLA class II/Ara h 1-specific tetramers were used to determine the frequency and phenotype of Ara h 1-reactive T cells in subjects with peanut allergy. Cytokine profiles of Ara h 1-reactive T cells were also determined.

RESULTS

Multiple Ara h 1 epitopes with defined HLA restriction were identified. Ara h 1-specific CD4(+) T cells were detected in all of the subjects with peanut allergy tested. Ara h 1-reactive T cells in subjects with allergy expressed CCR4 but did not express CRTH2. The percentage of Ara h1-reactive cells that expressed the β7 integrin was low compared with total CD4(+) T cells. Ara h 1- reactive cells that secreted IFN-γ, IL-4, IL-5, IL-10, and IL-17 were detected.

CONCLUSION

In individuals with peanut allergy, Ara h 1-reactive T cells occurred at moderate frequencies, were predominantly CCR4(+) memory cells, and produced IL-4. Class II tetramers can be readily used to detect Ara h 1-reactive T cells in the peripheral blood of subjects with peanut allergy without in vitro expansion and would be effective for tracking peanut-reactive CD4(+) T cells during immunotherapy.

Effects of hydrocortisone on the differentiation of human T helper 2 cells

We investigated the effects of the neuroendocrine modulator hydrocortisone (HC) on Th2 differentiation of human naive CD4+ T cells with and without CD28 co-stimulation. Human naive CD4+ T cells were isolated and purified from umbilical cord blood mononuclear cells from full-term newborn infants. CD4+ T cells were treated with different concentrations of HC under Th0 or Th2 culture conditions. Th0 conditions included stimulation by immobilized monoclonal antibodies (mAbs) against CD3 and CD28; Th2 conditions were the same + rhIL-4. Parallel cultures excluded the CD28 mAb. Th1 (IL-2, INF-γ)- and Th2 (IL-4, IL-5)-type cytokines were quantified in culture supernatants by ELISA and within cells by flow cytometry. For both Th0 and Th2 culture conditions, HC significantly inhibited Th1 cytokines' release (IL-2 and INF-γ). For Th0 culture conditions, HC slightly increased IL-4 expression (Th2 cytokine). However, for Th2 culture conditions, HC inhibited the IL4-induced production of IL-4. Although the absolute cytokine amounts were decreased, absence of CD28 co-stimulation did not alter these 'trends'. Our findings indicate that HC can alter the Th1/Th2 balance by inhibiting the production of Th1-type cytokines. HC can also diminish the extensive Th2 differentiation induced by IL-4.

Pathogenesis of airway inflammation in bronchial asthma

Bronchial asthma is a chronic disorder characterized by airway inflammation, reversible airway obstruction, and airway hyperresponsiveness. Eosinophils are believed to play important roles in the pathogenesis of asthma through the release of inflammatory mediators. In refractory eosinophilic asthma, anti-IL-5 mAb reduces exacerbations and steroid dose, indicating roles of eosinophils and IL-5 in the development of severe eosinophilic asthma. Even in the absence of IL-5, it is likely that the "Th2 network", including a cascade of vascular cell adhesion molecule-1/CC chemokines/GM-CSF, can sufficiently maintain eosinophilic infiltration and degranulation. Cysteinyl leukotrienes can also directly provoke eosinophilic infiltration and activation in the airways of asthma. Therefore, various mechanisms would be involved in the eosinophilic airway inflammation of asthma. In the pathogenesis of severe asthma, not only eosinophils but also mast cells or neutrophils play important roles. Mast cells are much infiltrated to smooth muscle in severe asthma and induce airway remodeling by release of inflammatory mediators such as amphiregulin. Treatment with anti-IgE Ab, which neutralizes circulating IgE and suppresses mast cell functions, reduces asthma exacerbations in severe asthmatic patients. Furthermore, infiltration of neutrophils in the airway is also increased in severe asthma. IL-8 plays an important role in the accumulation of neutrophils and is indeed upregulated in severe asthma. In the absence of chemoattractant for eosinophils, neutrophils stimulated by IL-8 augment the trans-basement membrane migration of eosinophils, suggesting that IL-8-stimulated neutrophils could lead eosinophils to accumulate in the airways of asthma. In view of these mechanisms, an effective strategy for controlling asthma, especially severe asthma, should be considered.

12/15-lipoxygenase is an interleukin-13 and interferon-γ counterregulated-mediator of allergic airway inflammation

Interleukin-13 and interferon-γ are important effectors of T-helper cells. Interleukin-13 increases expression of the arachidonic acid-metabolizing enzyme, 15-lipoxygenase-1, in a variety of cell types. 15-lipoxygenase-1 is dramatically elevated in the airways of subjects with asthma. Studies in animals indicate that 15-lipoxygenase-1 contributes to the development of allergic airway inflammation but is protective in some other forms of inflammation. We tested the hypothesis that the ability of interleukin-13 and interferon-γ to counterregulate allergic airway inflammation was potentially mediated by counterregulation of 12/15-lipoxygenase, the mouse ortholog of 15-lipoxygenase-1. The airways of mice were treated with interleukin-13 or interferon-γ one day prior to each of the four allergen exposures. Interleukin-13 augmented and interferon-γ inhibited allergic airway inflammation independently of systemic IgE and mucosal IgA responses but in association with counterregulation of 12/15-lipoxygenase. Interleukin-13 and interferon-γ counterregulate 12/15-lipoxygenase potentially contributing to the effects of these cytokines on allergic airway inflammation.

Interleukin-17 regulation: an attractive therapeutic approach for asthma

Interleukin (IL)-17 is recognized to play a critical role in numerous immune and inflammatory responses by regulating the expression of various inflammatory mediators, which include cytokines, chemokines, and adhesion molecules. There is growing evidence that IL-17 is involved in the pathogenesis of asthma. IL-17 orchestrates the neutrophilic influx into the airways and also enhances T-helper 2 (Th2) cell-mediated eosinophilic airway inflammation in asthma. Recent studies have demonstrated that not only inhibitor of IL-17 per se but also diverse regulators of IL-17 expression reduce antigen-induced airway inflammation, bronchial hyperresponsiveness, and Th2 cytokine levels in animal models of asthma. This review will summarize the role of IL-17 in the context of allergic airway inflammation and discuss the therapeutic potential of various strategies targeting IL-17 for asthma.

An alternative to lung inflammation and fibrosis

This Commentary discusses the role of NFkappaB signaling in lung inflammation and fibrosis.

Plasticity of T-cell phenotype and function: the T helper type 17 example

Mature T helper type 1 (Th1) and Th2 cells antagonize the development of the opposing subset to sustain lineage-specific responses. However, the recent identification of a third distinct subset of helper T cells - the Th17 lineage - collapses the established Th1/Th2 dichotomy and raises intriguing questions about T-cell fate. In this review, we discuss the Th17 subset in the context of the effector and regulatory T-cell lineages. Initial studies suggested reciprocal developmental pathways between Th17/Th1 subsets and between Th17/regulatory T-cell subsets, and identified multiple mechanisms by which Th1 and Th2 cells antagonize the generation of Th17 cells. However, recent observations reveal the susceptibility of differentiated Th17 cells to Th1 polarization and the enhancement of Th17 memory cells by the Th1 factors interferon-gamma and T-bet. In addition, new data indicate late-stage plasticity of a subpopulation of regulatory T cells, which can be selectively induced to adopt a Th17 phenotype. Elucidating the mechanisms that undermine cross-lineage suppression and facilitate these phenotype shifts will not only clarify the flexibility of T-cell differentiation, but may also shed insight into the pathogenesis of autoimmunity and cancer. Furthermore, understanding these phenomena will be critical for the design of immunotherapy that seeks to disrupt lineage-specific T-cell responses and may suggest ways to manipulate the balance between pathogenic and regulatory lymphocytes for the restoration of homeostasis.

Precarious balance: Th17 cells in host defense

Lineage-specific responses from the effector T-cell repertoire form a critical component of adaptive immunity. The recent identification of Th17 cells-a third, distinct lineage of helper T cells-collapses the long-accepted paradigm in which Th1 and Th2 cells distinctly mediate cellular and humoral immunity, respectively. In this minireview, we discuss the involvement of the Th17 lineage during infection by extracellular bacteria, intracellular bacteria, and fungi. Emerging trends suggest that the Th17 population bridges innate and adaptive immunity to produce a robust antimicrobial inflammatory response. However, because Th17 cells mediate both host defense and pathological inflammation, elucidation of mechanisms that attenuate but do not completely abolish the Th17 response may have powerful implications for therapy.