B7-1 (CD80) and B7-2 (CD86) have complementary roles in mediating allergic pulmonary inflammation and airway hyperresponsiveness

Neferine Attenuates HDM-Induced Allergic Inflammation by Inhibiting the Activation of Dendritic Cell

House dust mite (HDM) acts as an environmental antigen that might cause chronic allergic diseases. Neferine (NEF) shows anti-inflammation therapeutic effects. This study is to explore the protection role of NEF against HDM-induced allergic inflammation. HDM-induced allergic asthmatic C57BL/6J mice models were established. Differential histological staining was used to analyze lung tissue pathological scores. Flow cytometry was used to analyze subtypes and biomarker expression of immune cells. RT-PCR and ELISA were used to test cytokines-related gene and/or protein expression levels. Western blot was performed to investigate the signaling pathway that mediates allergic inflammation from mice lung tissue and bone marrow-derived dendritic cells (BMDCs). H&E and PAS staining results indicate NEF significantly attenuated inflammatory index and the percentage of goblet cells in the lung tissue induced by HDM. The HDM-elevated TH2 and TH17 cells were significantly decreased by NEF; inflammatory cytokines Il-4, Il-13 and Il-17 were dramatically downregulated in the NEF plus HDM group compared with HDM alone. CD40+ and CD86+ DCs, eosinophils and mast cells, and ILC2 cells were decreased by NEF which was elevated under HDM stimulation. In vivo and ex vivo investigations indicated NEF can attenuate the activated NF-κB signaling induced by HDM is involved in allergic inflammatory immune response and regulates cytokines-related gene expression. HDM-activated DCs promoted differentiation of TH2 and TH17 cells but were attenuated by NEF. This study suggests NEF interrupts the overexpression of some cytokines released by DCs, TH2, and TH17 cells; NEF attenuates HDM-induced allergic inflammation via inhibiting NF-κB signaling of DCs.

Effect of early postnatal supplementation of newborns with probiotic strain E. coli O83:K24:H31 on allergy incidence, dendritic cells, and microbiota

Introduction

Probiotic administration seems to be a rational approach to promote maturation of the neonatal immune system. Mutual interaction of the microbiota with the host immune system is critical for the setting of appropriate immune responses including a tolerogenic one and thevmaintenance of homeostasis. On the other hand, our knowledge on the modes of actions of probiotics is still scarce.

Methods

In our study, probiotic strain Escherichia coli O83:K24:H31 (EcO83) was administered to neonates of allergic mothers (AMs; neonates with increased risk for allergy development) within 48 h after the delivery, and the impact of this early postnatal supplementation on allergy incidence and selected immune markers has been analyzed 10 years after the primary EcO83 administration.

Results

We have observed decreased allergy incidence in 10-year-old children supplemented with EcO83 (13 of 52 children were allergic) in comparison with non-supplemented children of AMs (16 of 42 children were allergic). The early postnatal EcO83 supplementation appeared to limit the allergy in the high-risk group (children of AMs) compared to that in the low-risk group (children of healthy mothers). Dendritic cells (DCs) in the peripheral blood of EcO83-supplemented children do not differ significantly in cell surface presence of CD83. The immunomodulatory capacity of EcO83 on DCs was tested in vitro as well. Both directly isolated myeloid and in vitro monocyte-derived DCs from cord blood increased CD83 expression together with interleukin (IL)-10 secretion after EcO83 stimulation. The effect of early postnatal EcO83 supplementation on the microbiota composition of 10-year-old children was characterized by next-generation sequencing, and we have not observed significant changes in the microbiota composition of EcO83-supplemented and non-supplemented children at the age of 10 years.

Conclusions

Early postnatal EcO83 supplementation appears to lower allergy incidence in children of AMs. It seems that the beneficial effect of EcO83 is mediated via modulation of DC functional capacities without impacting the microbiota composition. Larger-scale studies will be necessary to confirm these preliminary findings.

Oligomeric proanthocyanidins attenuate airway inflammation in asthma by inhibiting dendritic cells maturation

To date, although a promising anti-inflammatory activity of oligomeric proanthocyanidins (OPCs) has been observed in asthma, the mechanism responsible for these immunomodulatory properties remains obscure. Dendritic cells (DCs) that reside in the airway have been widely perceived as an important contributor to asthma. Our study was to demonstrate OPCs' effects on maturation and immunoregulation of pulmonary CD11c⁺ dendritic cells (DCs). BALB/c mice were exposed to ovalbumin (OVA) to induce murine model of asthma. In addition, pulmonary DCs and bone marrow-derived DCs (BMDCs) cultures were used to evaluate impacts of OPCs on DCs function. The results obtained here indicated that OPCs treatment dramatically reduced airway inflammation, such as the infiltration of inflammatory cells and the levels of allergen-specific serum IgE and Th2 cytokines. The expression of co-stimulatory molecules especially CD86 distributed on pulmonary DCs and bone marrow-derived DCs (BMDCs) also markedly declined. The phosphorylation of cAMP responsive element-binding protein (CREB) was significantly inhibited while no changes were observed in the expression of cAMP responsive element modulator (CREM). By transferring BMDCs into the airways of naïve mice, we found that OPCs-treated DCs (DC+OVA+OPC) were much less potent in promoting CD4⁺ T cells proliferation than OVA-pulsed DCs (DC+OVA), followed by the ameliorated eosinophilic inflammation in airway. Our findings tailor a novel profile of OPCs in the regulation of DCs function, shedding new light on the therapeutic potential of OPCs in asthma management.

Adhesion molecules as predictors of nasal polyposis recurrence

BACKGROUND

Nasal polyposis is a chronic inflammation of nasal and paranasal sinuses in the pathogenesis of which adhesion molecules may have a significant role. This study investigates the possible role of certain adhesion molecules, mucins, and oncogenes in nasal polyposis recurrence.

METHODS

A sample study of 21 individuals (17 men and 4 women) aged 47.44 ± 15.10 years with nasal polyposis who had undergone nasal surgery twice was used. Twenty-one individuals aged 46.9 ± 12.8 years suffering from nasal polyposis who had undergone surgery only once in the same period were used as a control sample.

RESULTS

Statistically significant differences between the two groups were observed regarding epithelial membrane antigen (EMA/mucin 1) of stromal cells (p < 0.001) and CD86 stromal expression (p = 0.009). No patient of the control group exhibited high (++) CD86 stromal expression, whereas six patients of the resurgery group did so. When EMA and CD86 were included in a logistic regression model, stromal EMA was found to be positively related to recurrence.

CONCLUSION

Adhesion molecules may relate to nasal polyp prognosis and recurrence rates.

T cells and lung injury. Impact of rapamycin

Acute lung injury (ALI) is characterized by pulmonary inflammation and edema. Innate immune cells (e.g., neutrophils and macrophages) are major contributors to inflammation in ALI. Less is known regarding the role of T cells. We examined the effects of rapamycin on inflammation in a LPS-induced murine model of ALI. Rapamycin was administered before and after initiation of injury. Inflammatory parameters, including bronchoalveolar lavage cell counts, T cell surface markers (i.e., cytotoxic T lymphocyte antigen 4 [CTLA4] and fork head-winged helix transcription factor [Foxp3]), T cell activation (CD69), IL-6, and IL-10 were analyzed. Rapamycin significantly decreased inflammatory parameters and decreased Foxp3, CTLA4, and CD69 in CD4(+) T cells. Rapamycin administration before or after the onset of lung injury, as well as systemically or by pulmonary routes, ameliorates inflammation in ALI.

Reduction of eotaxin production and eosinophil recruitment by pulmonary autologous macrophage transfer in a cockroach allergen-induced asthma model

We sought to investigate the effects of cockroach allergen (CRA) exposure on the lung macrophage population to determine how different macrophage phenotypes influence exacerbation of disease. CRA exposure caused significantly reduced expression of CD86 on lung macrophages. These effects were not systemic, as peritoneal macrophage CD86 expression was not altered. To investigate whether naïve macrophages could reduce asthma-like pulmonary inflammation, autologous peritoneal macrophages were instilled into the airways 24 h before the final CRA challenge. Pulmonary inflammation was assessed by measurement of airway hyperresponsiveness, mucin production, inflammatory cell recruitment, and cytokine production. Cell transfer did not have significant effects in control mice, nor did it affect pulmonary mucin production or airway hyperresponsiveness in control or CRA-exposed mice. However, there was significant reduction in the number of eosinophils recovered in the bronchoalveolar lavage (BAL) (5.8 × 10⁵ vs. 0.88 × 10⁵), and total cell recruitment to the airways of CRA-exposed mice was markedly reduced (1.1 × 10⁶ vs. 0.57 × 10⁶). The reduced eosinophil recruitment was reflected by substantially lower levels of eosinophil peroxidase in the lung and significantly lower concentrations of eotaxins in BAL (eotaxin 1: 3 pg/ml vs. undetectable; eotaxin 2: 2,383 vs. 131 pg/ml) and lung homogenate (eotaxin 1: 1,043 vs. 218 pg/ml; eotaxin 2: 10 vs. 1.5 ng/ml). We conclude that CRA decreases lung macrophage CD86 expression. Furthermore, supplementation of the lung cell population with peritoneal macrophages inhibits eosinophil recruitment, achieved through reduction of eotaxin production. These data demonstrate that transfer of naïve macrophages will reduce some aspects of asthma-like pulmonary inflammation in response to CRA.

A comprehensive post-market review of studies on a probiotic product containing Lactobacillus helveticus R0052 and Lactobacillus rhamnosus R0011

The probiotic preparation Lacidofil® has been commercially available in Europe, Asia and North America since 1995. This product is a combination of two strains, Lactobacillus helveticus R0052 and Lactobacillus rhamnosus R0011. The strains have been evaluated for safety, identity and mechanisms of probiotic action in vitro, in animal models and human clinical trials. The strains adhered to human epithelial cells, helped to maintain the barrier function and blocked the adhesion of a number of pathogens, allowing them to be cleared from the intestine. The strains also elicited an anti-inflammatory response by down-regulating IL-1β, IL-8 and TNF-α. In various stress models, the probiotic combination facilitated better coping and outcomes which may be through the maintenance of barrier function and suppressing inflammation. Overall, pre-clinical studies suggest a potential anti-infectious role for the strains and the combination. Clinical studies, primarily in children, have identified Lacidofil as an effective supplement for various gastrointestinal diseases such as antibiotic-associated diarrhoea and acute gastroenteritis. Recent research has also indicated that Lacidofil may be beneficial for individuals with atopic dermatitis or vaginal dysbacteriosis.

Preferential use of B7.2 and not B7.1 in priming of vaccinia virus-specific CD8 T cells

Recent studies have demonstrated that CD28 provides critical costimulatory signals required for optimal CD8 T cell expansion and effector function in response to several viruses, including influenza, HSV, and vaccinia virus (VACV). CD28 has two ligands expressed largely on professional APC, named B7.1 (CD80) and B7.2 (CD86). Although some results suggest that these ligands are equivalent and both promote CD28 signaling, it is not clear whether they are equally important for priming of antiviral T cells. Herein we show that B7.2 is critical for early CD8 T cell responses to both dominant and subdominant VACV epitopes, correlating with its strong induction on CD8alpha(+) dendritic cells. In contrast, B7.1 plays no significant role. Signals from an exogenously applied adjuvant can recruit B7.1 activity and lead to further enhanced priming of VACV-reactive CD8 T cells. However, during a natural infection, B7.1 is not functional, likely related to inefficient up-regulation or active suppression by VACV. These studies provide evidence that B7.2 is the major ligand for the CD28 receptor on VACV-specific CD8 T cells, that B7.2 can promote efficient CD8 T cell priming without B7.1, and that B7.1 and B7.2 can be differentially utilized during antiviral responses.

Induction of IL-10 producing CD4+ T cells with regulatory activities by stimulation with IL-10 gene-modified bone marrow derived dendritic cells

Dendritic cells (DCs) can induce both tolergenic as well as effective immune responses in the lung. Pulmonary DCs producing interleukin (IL)-10 mediated tolerance induced by respiratory exposure to antigen. IL-10 is an important immunosuppressive cytokine, which inhibits maturation and function of DC. To assess whether IL-10 producing DCs can exert the tolergenic effect through the differentiation of regulatory T cells, bone marrow derived DCs were genetically modified by IL-10 expressing adenovirus. IL-10 gene modified DCs (Ad-IL-10-DC) displayed a characteristic phenotype of immature DCs. Here we showed that in vitro repetitive stimulation of naïve DO11.10 CD4(+) T cells with Ad-IL-10-DCs resulted in a development of IL-10 producing T-cell regulatory cells. These T cells could not proliferate well but also lost their ability to produce interferon-gamma upon restimulation with irradiated splenocytes and ovalbumin peptide. Furthermore, in co-culture experiments these T cells inhibited the antigen-driven proliferation of naïve CD4+ T cells in a dose-dependent manner. Our findings demonstrated that IL-10 producing DCs had the potential to induce the differentiation of Tr1-like cells and suggested their therapeutic use.

Costimulation and allergic responses: immune and bioinformatic analyses

Asthma is a complex polygenic disease, the prevalence of which has been on the rise for last few decades. Defining the underpinnings of allergic immune responses and the factors predisposing to asthma are fundamental investigative challenges. T cell costimulatory pathways play critical roles in the pathogenesis of asthma. In this review, we analyze the current state of the art of T cell costimulation in allergic airway inflammation. Also, we discuss both immune and bioinformatic approaches as potential strategies for analyzing multiple costimulatory pathways relevant to asthma.

CD45RB ligation inhibits allergic pulmonary inflammation by inducing CTLA4 transcription

CD45, a type I transmembrane protein tyrosine phosphatase expressed on nucleated hemopoietic cells, is prominently involved in T cell activation. Ligation of CD45RB isoforms has been associated with transplant tolerance. A recent genotyping analysis of asthma indicates a correlation with CD45 splicing. In this study, we administered an anti-CD45RB mAb (aCD45) in a murine model of allergic asthma and found that CD45RB ligation decreases allergic responses. aCD45 decreases allergen-induced pulmonary eosinophilia, bronchoalveolar lavage IL-13, IgE, and airway responses. Also, aCD45 increases the expression of CTLA4, a negative regulator of T cell activation. Furthermore, CD45RB signals no longer decrease allergic inflammation when CTLA4 is inhibited. These data support a role for CTLA4 in CD45RB-mediated inhibition of allergic inflammation. T cells and splenocytes stimulated with aCD45 exhibited increased CTLA4 levels, and analysis of CTLA4 promoter gene constructs identified a CD45RB-inducible regulatory region localized from -335 to -62 bp relative to the transcription start site. Together, these findings suggest that CD45RB signals mediate a novel role in the modulation of allergic inflammation, orchestrated by T cells through induction of CTLA4 transcription.

Inhaled CD86 antisense oligonucleotide suppresses pulmonary inflammation and airway hyper-responsiveness in allergic mice

The B7-family molecule CD86, expressed on the surface of pulmonary and thoracic lymph node antigen-presenting cells, delivers essential costimulatory signals for T-cell activation in response to inhaled allergens. CD86-CD28 signaling is involved in priming allergen-specific T cells, but it is unclear whether these interactions play a role in coordinating memory T-helper 2 cell responses. In the ovalbumin (OVA)-induced mouse model of asthma, administration of CD86-specific antibody before systemic sensitization suppresses inhaled OVA-induced pulmonary inflammation and airway hyper-responsiveness (AHR). In previously OVA-sensitized mice, systemic and intranasal coadministration of CD86 antibody is required to produce these effects. To directly assess the importance of pulmonary CD86 expression in secondary immune responses to inhaled allergens, mice were sensitized and locally challenged with nebulized OVA before treatment with an inhaled aerosolized CD86 antisense oligonucleotide (ASO). CD86 ASO treatment suppressed OVA-induced up-regulation of CD86 protein expression on pulmonary dendritic cells and macrophages as well as on recruited eosinophils. Suppression of CD86 protein expression correlated with decreased methacholine-induced AHR, airway inflammation, and mucus production following rechallenge with inhaled OVA. CD86 ASO treatment reduced BAL eotaxin levels, but it did not reduce CD86 protein on cells in the draining lymph nodes of the lung, and it had no effect on serum IgE levels, suggesting a local and not a systemic effect. These results demonstrate that CD86 expression on pulmonary antigen-presenting cells plays a vital role in regulating pulmonary secondary immune responses and suggest that treatment with an inhaled CD86 ASO may have utility in asthma and other chronic inflammatory lung conditions.

A negative regulatory role in mouse cardiac transplantation for a splice variant of CD80

BACKGROUND

Members of the B7 costimulatory protein family (CD80 and CD86) play a determining role in allograft rejection. Both CD80 and CD86 have naturally occurring splice variants whose roles in transplantation are unknown. Full length CD80 has two immunoglobulin (Ig)-like domains in the extracellular portion, IgC and IgV. In mouse, the isoform IgV-CD80 lacks the IgC-like domain. Here we analyzed the role of mouse IgV-CD80 in heart allograft rejection and search for equivalent splice variants in human.

METHODS

Mice made deficient for full-length CD80 but which retain expression of the shorter IgV-CD80 (CD80 mice) were used as donor or recipient of a heart allograft. Recipient animals were untreated or pretreated with alloantigen expressing cells and/or treated with CD80 and CTLA4 monoclonal antibodies (mAbs).

RESULTS

Recipients expressing IgV-CD80 but not full length CD80 exhibited a slight prolongation in survival of either wild-type (Wt) or CD80 grafts. More dramatically, CD80 animals pretreated with donor alloantigen exhibited permanent graft survival, whereas their Wt counterparts rejected their grafts with a median survival of 24 days. This prolonged survival was due to the expression of IgV-CD80 in recipients since treatment with CD80 mAb abrogated the beneficial effect observed. We identified and report here a similar isoform of CD80 from human cDNA encoding a putative soluble, IgV-containing protein.

CONCLUSIONS

IgV-CD80 bearing recipients show enhanced allograft survival especially after donor alloantigen pretreatment. This together with data from other species suggests that regulation delivered by splice variants of CD80 significantly modulates immunity and may be common across the species.

Differential contributions of B7-1 and B7-2 to the development of murine experimental allergic conjunctivitis

B7-1 and B7-2 are the co-stimulatory molecules that are involved in activation of T cells. We investigated whether B7-1 and B7-2 play a role in the development of T cell-mediated experimental allergic conjunctivitis (EC). EC was induced in Balb/c mice by active immunization with ragweed (RW) followed by RW challenge in eye drops. These mice were treated with neutralizing anti-B7-1 Ab, anti-B7-2 Ab, both Abs, anti-cytotoxic T lymphocyte-associated Ag-4 (CTLA-4) Ab or normal IgGs as controls either during the induction phase or the effector phase. With regard to the induction phase treatment, EC was significantly attenuated when both anti-B7-1 and anti-B7-2 Abs were injected. In contrast, anti-CTLA-4 Ab treatment significantly exacerbated EC. With regard to the effector phase treatment, anti-B7-2 Ab alone significantly attenuated EC, while anti-CTLA-4 Ab tended to exacerbate EC. Collectively, B7-1 and B7-2 differently contribute to the development of EC during the induction and effector phases.

Co-stimulatory molecules as potential targets for therapeutic intervention in allergic airway disease

Airway inflammation is a characteristic feature of allergic asthma. Central to the initiation and progression of the inflammatory process are allergen-specific T lymphocytes that attract eosinophils, mast cells, and B cells to the airways by the secretion of specific cytokines. The direction of T cell responses is influenced by co-stimulatory signals that modulate the antigen-specific signal delivered by the T cell receptor. In addition to the prototypic co-stimulatory molecule, CD28, a number of newly identified co-stimulatory molecules and their ligands have now been characterized. Over the past 5 years, the role of these molecules in the pathophysiology of allergen-mediated sensitization and airway inflammation has been extensively studied in animal models of allergic asthma. The aim of this review is to provide a detailed overview on recent studies in mice and preliminary findings in man and to discuss the potential therapeutic and preventive treatment strategies offered by interactions with co-stimulatory molecules for patients with allergic airway diseases.

The costimulatory molecule SLAM is critical for pulmonary allergic responses

T-cell activation plays an essential role in the generation of the pulmonary inflammation that is manifest in allergic asthma. Optimal T-cell activation requires not only presentation of antigen with the major histocompatibility complex, but also concurrent signaling through costimulatory molecules. The costimulatory molecule SLAM (Signaling Lymphocytic Activation Molecule, CD150) is a glycoprotein expressed on activated lymphocytes and antigen-presenting cells. Disruption of the SLAM gene demonstrated that SLAM-induced signal transduction pathways regulate cytokine production by T helper (Th)2 cells and macrophages. Here we tested the postulate that the costimulatory molecule SLAM may be critical for allergic inflammation in a murine model. SLAM-deficient mice did not manifest allergen-induced bronchoalveolar lavage eosinophilia, increased serum IgE, or heightened airway responses compared with wild-type mice. Allergen-induced Th2 cytokines and Th1 cytokines were decreased in SLAM-deficient mice. These data support the concept that SLAM plays a crucial role in allergic responses.

CD28/CTLA-4--CD80/CD86 and ICOS--B7RP-1 costimulatory pathway in bronchial asthma

Costimulatory molecules are cell surface glycoproteins that can direct, modulate and fine-tune T-cell receptor signals. The B7-1/B7-2--CD28/CTLA-4 and ICOS-B7RP-1 pathway provides key second signals that can regulate the activation, inhibition and fine-tuning of T-lymphocyte responses. The expression of B7-1/B7-2--CD28/CTLA-4 molecules on clinical samples from patients with asthma have been well studied, and the results indicate that different extents of these molecules are expressed on the surface of various cells, and that the concentrations of soluble form of these molecules are elevated in the sera of patients with asthma. There is a burst of papers describing an important role for B7-1/B7-2--CD28/CTLA-4 pathway in the Th1/Th2 balance. Similarly, ICOS stimulates both Th1 and Th2 cytokine production but may have a preferential role in Th2 cell development. Moreover, The B7-1/B7-2-CD28/CTLA-4 and ICOS-B7RP-1 pathway has been suggested of being involved in the development of airway inflammation and airway hyperresponsiveness. Further study of the functions of the pathways within the CD28/CTLA-4--CD80/CD86 and ICOS--B7RP-1 superfamily individually and their interplay should provide insights into the pathogenesis of asthma, and has great therapeutic potential for treatment of asthma.

The costimulatory molecules CD80, CD86 and OX40L are up-regulated in Aspergillus fumigatus sensitized mice

Aspergillus fumigatus (Af) is a fungus associated with allergic bronchopulmonary aspergillosis (ABPA) and other allergic diseases. Immune responses in these diseases are due to T and B cell responses. T cell activation requires both Af-specific engagement of the T-cell-receptor as well as interaction of antigen independent costimulatory molecules including CD28-CD80/CD86 and OX40-OX40L interactions. Since these molecules and their interactions have been suggested to have a potential involvement in the pathogenesis of ABPA, we have investigated their role in a model of experimental allergic aspergillosis. BALB/c mice were primed and sensitized with Af allergens, with or without exogenous IL-4. Results showed up-regulation of both CD86 and CD80 molecules on lung B cells from Af-sensitized mice (79% CD86+ and 24% CD80+) and Af/rIL-4-treated mice (90% CD86+ and 24% CD80+) compared to normal controls (36% and 17%, respectively). Lung macrophages in Af-sensitized mice treated or not with IL-4 showed enhanced expression of these molecules. OX40L expression was also up-regulated on lung B cells and macrophages from both Af-sensitized and Af/rIL-4 exposed mice as compared to normal controls. All Af-sensitized animals showed peripheral blood eosinophilia, enhanced total serum IgE and allergen-specific IgG1 antibodies and characteristic lung inflammation. The up-regulation of CD80, CD86 and OX40L molecules on lung B cells and macrophages from Af-allergen exposed mice suggests a major role for these molecules in the amplification and persistence of immunological and inflammatory responses in ABPA.

What targets have knockouts revealed in asthma?

There have been numerous studies of mice rendered genetically deficient of various genes in the context of allergic inflammatory airway disease. These studies have provided invaluable information about basic immune processes, but have also been considered to be useful in predicting novel pharmacological targets. In this review, the effect of a wide range of individual knockouts (KO) on the development of asthma-like pathologies in mice is compiled and considered. How the results of these studies compare with effects of agents that interfere with the function of each gene product, where known, is also described. Finally, a personal view of the utility of these studies in drug development is presented.

B7.2-/- mature dendritic cells generate T-helper 2 and regulatory T donor cells in fetal mice after in utero allogeneic bone marrow transplantation

In utero hematopoietic stem cell transplantation (IUT) results in limited chimerism and tolerance to alloantigens. We studied the relative role of B7.1 and B7.2 expression by dendritic cells (DCs) in engraftment and in generating donor-specific tolerance in fetal mice. Mature dendritic cells (mDCs) from B7.1(-/-) or B7.2(-/-) donors and wild-type (WT) lineage-depleted (lin(-)) C57BL/6 (B6) bone marrow (BM) were injected into BALB/c fetuses. Six weeks after IUT, B7.1(-/-) recipients had multilineage engraftment (4.7% +/- 0.8% T cells and 5.7% +/- 1.1% granulocytes) associated with graft-versus-host disease (GVHD) and decreased survival, but by 12 weeks only donor CD3(+) cells (2.1% +/- 1.3%) were present. Recipients of B7.2(-/-) mDCs and lin(-) WT B6 BM had exclusively CD3(+)CD4(+) T cells (11.8% +/- 8.5% at 6 weeks and 6.5% +/- 2.5% at 12 weeks). Most of the cells were T-helper 2, although 10.4% +/- 1.4% were of the T-regulatory (T(reg)) phenotype, ie, CD4(+)CD25(+). Donor T(reg) cells were detected both in the thymus and spleen, thus suggesting an effect on both central and peripheral immunity. The animals with T(reg) cells had better survival (82.3% versus 47.4%; P < .01) and no GVHD (0% versus 65%; P < .001). This group alone demonstrated multilineage engraftment of donor hematopoietic cells after postnatal transplantation with megadoses of donor lin(-) BM. Both the engrafted donor CD4(+)CD25(-) and CD4(+)CD25(+) cells induced comparable in vitro suppression of T-cell proliferation, thus suggesting their role in the persistence of the donor T cells in vivo. The CD4(+)CD25(-) cells produced interleukin 10 or interleukin 4 and were inhibited by anti-T-helper 2 cytokine-neutralizing antibodies, whereas the CD4(+)CD25(+) cells showed no evidence of any involvement of a cytokine-like soluble mediator and expressed cytotoxic T-lymphocyte antigen 4 (CTLA-4) and foxp3 constitutively. Donor mDCs and donor CD4 T cells were detected among the thymocytes of the recipients of B7.2(-/-) mDCs and lin(-) WT B6 BM. Thus, it seems that costimulatory molecule expression of donor DCs can play a significant immunomodulatory role in survival, GVHD, engraftment, and homing of allogeneic BM cells after IUT through the generation of T(reg) cells.

Costimulation: critical pathways in the immunologic regulation of asthma

T cells play an important role in the pathogenesis of allergy and asthma. T-cell receptor engagement by antigenic peptides presented to major histocompatibility complex (MHC) class II molecules and activation of costimulatory molecules are crucial in the regulation of T-cell immune responses. Costimulatory molecules are responsible for second signals that induce T-cell activation and proliferation. The best characterized costimulatory pathways include CD80/CD86 interacting with CD28, and a number of additional costimulatory molecules have recently been identified, including members of the tumor necrosis family. The positive signals induced by these molecules are counterbalanced by other members of the costimulatory family, including cytotoxic T lymphocyte-associated antigen (CTLA)-4, programmed death (PD)-1, and B and T lymphocyte attenuator (BTLA), which dampen immune responses. In this review, we describe the fundamental properties of costimulatory molecules and address the influence of costimulatory signals on allergic responses.

TLR2 and TLR4 stimulation differentially induce cytokine secretion in human neonatal, adult, and murine mononuclear cells

Toll-like receptor 2 (TLR2) and TLR4 signaling may induce differential secretion of T helper 1 (Th1) and Th2 cytokines, potentially influencing the development of autoimmune or atopic diseases. To date, the influence of the type of stimulus, timing, and dose of TLR2 and TLR4 ligands on cytokine secretion has not been well established. We tested whether the innate stimuli peptidoglycan (Ppg, TLR2 agonist) and lipid A (LpA, TLR4 agonist) differentially affect the secretion of interleukin-13 (IL-13) (Th2) and interferon-gamma (IFN-gamma) (Th1). Further, we examined the influence of the maturity of the immune system, species, dose, and timing of stimuli in human cord and adult peripheral blood mononuclear cells (PBMC) and murine cells in vitro and in vivo. Stimulation with Ppg induced the secretion of both IL-13 and IFN-gamma, influenced by time and dose in neonates, adults, and mice. In contrast, stimulation with LpA induced primarily time-independent and dose-independent production of IFN-gamma. Pulmonary administration of Ppg in vivo in mice resulted in secretion of IL-13, whereas administration of LpA resulted in secretion of IFN-gamma in bronchoalveolar lavage (BAL). Therefore, TLR2 and TLR4 stimuli differentially influence IL-13 and IFN-gamma secretion in neonates, adults, and mice, supporting a critical role for innate stimuli in the modulation of cytokine responses.

The Periarterial Space in the Lung: Its Important Role in Lung Edema, Transplantation, and Microbial or Allergic Inflammation

In mammal lungs different compartments for leukocytes can be identified during health and disease, e.g. lung interstitium, bronchoalveolar space, the epithelium and lamina propria of the air-conducting part. A so far neglected compartment is the space around the branches of the pulmonary arteries, characterized by a unique architecture of capillaries running in parallel to the pulmonary artery. This compartment - the periarterial space - is described and its physiological and pathophysiological role reviewed. The periarterial space is infiltrated by different leukocyte subsets during edema formation in the early stages of a lung transplant rejection and, in particular, during inflammatory and allergic reactions. The periarterial compartment seems to be of major relevance in all these situations.

Toll-like receptor 4 or 2 agonists decrease allergic inflammation

Toll-like receptors (TLRs) recognize highly conserved microbial molecular patterns, such as found in endotoxin. This study tested whether TLR4 and TLR2 stimulation in vivo would modulate subsequent adaptive (allergic) immune responses. We analyzed the effects of pulmonary administration of a TLR4 agonist, lipid A (LpA), and two TLR2 agonists, peptidoglycan (Ppg) and PamCys, in a murine model of allergic inflammation. The TLR agonists were administered during allergen sensitization or challenge. Both TLR agonists decreased the allergen-induced pulmonary recruitment of eosinophils when administered at sensitization or challenge. When given before sensitization, the TLR4 and TLR2 agonists decreased additional allergen-induced parameters of inflammation (pulmonary eosinophilia, bronchoalveolar lavage IL-13, total serum IgE, and airway hyperresponsiveness). Interestingly, TLR4 and TLR2 agonists decreased the number of CD4+ cells in the lung. Also, at the site of local allergen stimulation, the draining thoracic lymph nodes, allergen-induced lymphocyte proliferation, and IL-13 secretion were decreased by administration of LpA and Ppg. These data provide a distinct example of the modulation of adaptive (allergic) responses by non-antigen-dependent stimuli. Our findings also demonstrate that both TLR4 and TLR2 agonists decrease allergic responses, supporting the concept that exposure to bacterial components under defined conditions may protect against allergic disease.

Role of B7 in T cell tolerance

The induction of effective immune responses requires costimulation by B7 molecules, and Ag recognition without B7 is thought to result in no response or tolerance. We compared T cell responses in vivo to the same Ag presented either by mature dendritic cells (DCs) or as self, in the presence or absence of B7. We show that Ag presentation by mature B7-1/2-deficient DCs fails to elicit an effector T cell response but does not induce tolerance. In contrast, using a newly developed adoptive transfer system, we show that naive OVA-specific DO11 CD4+ T cells become anergic upon encounter with a soluble form of OVA, in the presence or absence of B7. However, tolerance in DO11 cells transferred into soluble OVA transgenic recipients can be broken by immunization with Ag-pulsed DCs only in B7-deficient mice and not in wild-type mice, suggesting a role of B7 in maintaining tolerance in the presence of strong immunogenic signals. Comparing two double-transgenic models--expressing either a soluble or a tissue Ag--we further show that B7 is not only essential for the active induction of regulatory T cells in the thymus, but also for their maintenance in the periphery. Thus, the obligatory role of B7 molecules paradoxically is to promote effective T cell priming and contain effector responses when self-Ags are presented as foreign.

Tyrosine kinase inhibitors: a new approach for asthma

The pathogenesis of allergic asthma involves the interplay of inflammatory cells and airway-resident cells, and of their secreted mediators including cytokines, chemokines, growth factors and inflammatory mediators. Receptor tyrosine kinases are important for the pathogenesis of airway remodeling. Activation of epidermal growth factor (EGF) receptor kinase and platelet-derived growth factor (PDGF) receptor kinase leads to hyperplasia of airway smooth muscle cells, epithelial cells and goblet cells. Stimulation of non-receptor tyrosine kinases (e.g. Lyn, Lck, Syk, ZAP-70, Fyn, Btk, Itk) is the earliest detectable signaling response upon antigen-induced immunoreceptor activation in inflammatory cells. Cytokine receptor dimerization upon ligand stimulation induces activation of Janus tyrosine kinases (JAKs), leading to recruitment and phosphorylation of signal transducer and activator of transcription (STAT) for selective gene expression regulation. Activation of chemokine receptors can trigger JAK-STAT pathway, Lck, Fyn, Lyn, Fgr, and Syk/Zap-70 to induce chemotaxis of inflammatory cells. Inhibitors of tyrosine kinases have been shown in vitro to block growth factor-induced hyperplasia of airway-resident cells; antigen-induced inflammatory cell activation and cytokine synthesis; cytokine-mediated pro-inflammatory gene expression in inflammatory and airway cells; and chemokine-induced chemotaxis of inflammatory cells. Recently, anti-inflammatory effects of tyrosine kinase inhibitors (e.g. genistein, tyrphostin AG213, piceatannol, tyrphostin AG490, WHI-P97, WHI-P131, Syk antisense) in animal models of allergic asthma have been reported. Therefore, development of inhibitors of tyrosine kinases can be a very attractive strategy for the treatment of asthma.

CD28/CTLA4 double deficient mice demonstrate crucial role for B7 co-stimulation in the induction of allergic lower airways disease

BACKGROUND

The existence of a third B7-1/B7-2 receptor was postulated in a recent study using a novel mouse strain lacking both CD28 and CTLA4 (CD28/CTLA4-/-).

OBJECTIVE

In the present study, it was investigated if T cell co-stimulation via the putative B7-1/B7-2 receptor plays a role in the induction of Th2-mediated asthma manifestations in mice.

METHODS

BALB/c wild-type, CD28/CTLA4-/- and B7-1/B7-2-/- mice were sensitized and aerosol challenged with ovalbumin (OVA).

RESULTS

At 24 h after the last aerosol, wild-type mice showed airway hyper-responsiveness in vivo and up-regulated levels of serum OVA-specific IgE compared with the situation shortly before OVA challenge. In addition, eosinophil numbers and IL-5 levels in the broncho-alveolar lavage fluid and Th2 cytokine production by lung cells upon OVA re-stimulation in vitro were observed. In agreement with an earlier study, we failed to induce any of the asthma manifestations in B7-1/B7-2-/- mice. Importantly, also CD28/CTLA4-/- mice showed no asthma manifestations upon OVA sensitization and challenge.

CONCLUSION

These data clearly demonstrate that T cell co-stimulation via the putative B7-1/B7-2 receptor appears to have no role in the induction of Th2-mediated asthma manifestations in this murine model and, conversely, that CD28 signalling is crucial.

Coarse(PM(2.5-10)), fine(PM(2.5)), and ultrafine air pollution particles induce/increase immune costimulatory receptors on human blood-derived monocytes but not on alveolar macrophages

Diesel particles have been shown to possess adjuvant activity and influence the development of allergic sensitization. Also, more heterogeneous mixtures of pollution particles have been shown to affect host defenses and development of immunity in animal models. In the present study it was determined whether freshly collected particulate matter (PM(10)) in the size ranges 2.5-10 micro m (PM(2.5-10), coarse), 0.1-2.5 micro m (PM(2.5), fine), and </=0.1 micro m (ultrafine) in diameter affected the development of antigen presenting cells by evaluating the expression of surface receptors involved in T-cell interaction on both human alveolar macrophages (AM) and blood-derived monocytes (Mo). A Mo-AM coculture was exposed to 50 micro g/ml of particles and expression of HLA-DR, CD40, CD80, and CD86 on each cell type was assessed by flow cytometry. Mo upregulated the expression of all four receptors in response to each of the particle fractions, while expression was unaffected in AM. The cells were also exposed to two model air pollution particles, diesel dust and volcanic ash, neither of which affected receptor expression. Furthermore, Mo and AM were separately exposed to the three PM size fractions and supernatants assessed for the T-helper (CD4(+)) lymphocyte chemoattractant interleukin-16 (IL-16). AM, but not Mo, produced IL-16, and this chemoattractant was released only in response to PM(2.5-10). These data suggest that a wide size range of pollution particles contain materials that may promote antigen presentation by Mo, while the capability to specifically recruit CD4(+) lymphocytes is contained in AM stimulated with the coarse PM fraction.

Upregulation of B7 molecules (CD80 and CD86) and exacerbated eosinophilic pulmonary inflammatory response in mice lacking the IFN-beta gene

BACKGROUND

IFN-beta has been shown to be effective as therapy for multiple sclerosis. Some reports attributed its beneficial effects to the capacity to induce a T(H)2 response. However, other studies have suggested that endogenous type I IFN might downregulate the allergic response in mice.

OBJECTIVE

We sought to define the differential role of endogenous IFN-beta in controlling the development of allergic inflammation.

METHODS

We assessed whether deletion of the gene encoding IFN-beta (IFNB) with knockout mice participated in the development of allergic response in ovalbumin (OVA)-sensitized and OVA-challenged mice.

RESULTS

OVA-sensitized and OVA-challenged mice with lack of the IFNB gene had more severe pulmonary inflammation with increased lung local response, including IL-4, IL-5, IL-13, IgE, eosinophilia, and goblet cells, than their litter mates (IFN-beta+/-), whereas no differences were observed in regard to local levels of IFN-gamma. Moreover, systemic response with IgE production is also enhanced. Lack of IFN-beta also results in significantly higher antigen-specific T cells, with higher levels of IL-4, IL-5, and IL-13, whereas no significant differences in IFN-gamma response could be observed. We have also detected a higher ratio of CD4+/CD8+ T cells and increased expression of B7.1/B7.2 on B cells and antigen-presenting cells in IFNB knockout mice.

CONCLUSIONS

These results demonstrate that IFN-beta plays an important role in immunoregulation of allergic response in mice. The stronger pulmonary inflammation could be a consequence of significantly expanded antigen-specific CD4+ T(H)2 cells as a result of efficient antigen presentation by antigen-presenting cells and hence increased production of IgE by B cells.

CD28 costimulation is critical for experimental allergic asthma in HLA-DQ8 transgenic mice

The objective of this study was to investigate the contribution of the CD28 costimulatory molecules to allergen-induced primary and chronic inflammatory responses. To this end, we have developed and characterized a short ragweed allergen-induced asthma model involving sensitization of HLA-DQ transgenic mice followed by intranasal challenge with allergen. Forty-eight hours after primary challenge, sensitized DQ8 mice developed pulmonary eosinophilic inflammation, airway hyperreactivity, Th2 cytokines, and IgE/IgG1 Ab. This allergic inflammatory response was absent in H-2Abeta(0) and DQ8/CD28(0) mice. Secondary rechallenge with allergen 4 weeks later induced even greater inflammatory changes in the airways of DQ8 mice with eosinophils being the predominant inflammatory cells while only pulmonary lymphocytosis was observed in DQ8/CD28(0) mice. No inflammation was detected in H-2Abeta(0) mice. Proliferation and cytokine profile studies demonstrated that CD28 regulates T-cell activation and effector function. Therefore, CD28 is essential for the extrinsic asthma and can be a target for immunotherapy.

Alterations in lung collectins in an adaptive allergic immune response

Although surfactant apoproteins are known to be mediators of innate responses, their relationship to adaptive responses has not been examined extensively. We investigated possible links between surfactant apoproteins and responses to allergens by studying alterations in surfactant apoproteins A, B, and D in a murine model of allergic pulmonary inflammation. Three murine strains (BALB/c, C57BL/6, and 129J) demonstrated increased immunostaining of surfactant apoproteins A and D in nonciliated epithelial cells of noncartilaginous airways after aerosolized challenge. In contrast, surfactant apoprotein B immunostaining was unchanged. Immunoblotting demonstrated increased surfactant A in bronchoalveolar lavage fluid after allergen sensitization and challenge. Surfactant apoprotein A and D induction required T and/or B lymphocyte responses to allergen, since the induction was absent in recombinase-activating gene-deficient mice, which lack functional lymphocytes. We conclude that increased immunoreactivity of two collectins, surfactant apoproteins A and D, occurs within the response to allergen. Our findings support a model in which surfactant apoproteins A and D are important to both innate immunity and adaptive immune responses to allergens.

Blockade of CD28/B7-2 costimulation inhibits experimental obliterative bronchiolitis in rat tracheal allografts: suppression of helper T cell type1-dominated immune response

T cell activation is a proximal event in the initiation of chronic rejection that may ultimately lead to obliterative bronchiolitis (OB) after lung transplantation. In addition to primary signals generated by the T cell receptor, T cell activation relies on costimulatory signals, of which the most important are mediated via interaction between CD28 and its ligands B7-1 and B7-2. In nontreated rat tracheal allografts, B7-2, but not B7-1, expression peaked 10 d after transplantation, unlike in syngeneic grafts, where no B7-2 upregulation was observed. Selective blockade of the CD28/B7-1 T cell costimulatory pathway by a mutant form of CTLA4Ig (cytotoxic T lymphocyte antigen 4 immunoglobulin), CTLA4IgY100F, did not affect epithelial injury or degree of luminal occlusion in rat tracheal allografts. Treatment with CTLA4Ig fusion protein, which blocks both CD28/B7-1 and CD28/B7-2 interaction, significantly delayed the development of epithelial injury and airway occlusion. Immunohistochemical analyses of allografts showed that selective inhibition of the CD28/B7-1 pathway did not affect cytokine expression. In contrast, treatment with CTLA4Ig was associated with a significant decrease in the intragraft production of tumor necrosis factor alpha, interleukin 2, and interferon gamma, as well as slightly increased intragraft expression of interleukin 10. In conclusion, CTLA4Ig-mediated costimulatory blockade delays epithelial injury and attenuates obliterative changes and is associated with marked suppression of helper T cell type 1 (Th1)-dominated cytokine response. These observations emphasize the role of the CD28/B7-2 costimulatory pathway in regulating proinflammatory and Th1 cytokine responses and thereby in the development of epithelial and graft injury gradually leading to obliteration of the airway lumen.

Temporal-spatial analysis of the immune response in a murine model of ovalbumin-induced airways inflammation

The objective of this study was to define phenotypic changes of antigen-presenting cells (APCs) and T cells in a murine model of antigen-induced airways inflammation that involves intraperitoneal sensitization with ovalbumin (OVA)/adjuvant followed by antigen aerosolization. We investigated the APC and T-cell compartments both after sensitization (primary immune response) and after challenge (secondary immune response) at the thoracic lymph nodes (initiation site) and the lung (effector site). Our findings document a major cellular expansion in the lymph nodes after both sensitization and challenge. After sensitization, this expansion was comprised mainly of B cells, a considerable proportion of which expressed B7.2. At this time, T cells were markedly expanded and activated as assessed by CD69 expression; further, although GATA-3 and signal transducer and activator of transcription-6 were expressed at this time point, expression of interleukin (IL)-4, IL-5, and IL-13 messenger RNA (mRNA) levels were marginal. However, in vitro stimulation of lymph-node cells with OVA led to cytokine production. In contrast, 24 h after challenge, but not after sensitization, there was a major expansion of dendritic cells and macrophages in the lungs. This expansion was associated with enhanced expression of both B7.1 and B7.2. We also observed expansion of activated CD3(+)/CD4(+) T cells expressing the T helper-2-associated marker T1/ST2 in the lung, most notably 5 d after challenge. Further, IL-4, IL-5, and IL-13, but not interferon-gamma mRNA were expressed at high levels 3 h after challenge. This study helps to elucidate the "geography" of immune responses generated in a conventional murine model of allergic airways inflammation.

Differential role of CD80 and CD86 on alveolar macrophages in the presentation of allergen to T lymphocytes in asthma

In the asthmatic lung the altered expression of costimulatory molecules (CD80, CD86) by alveolar macrophages contributes to T lymphocyte activation and expansion. We hypothesized that CD80 and CD86 on alveolar macrophages could differentially support allergic inflammation in adult asthma. Here we studied 11 subjects with mild allergic asthma and 11 atopic non-asthmatics as controls. Dermatophagoides-specific T cell lines were derived from peripheral blood from each subject. Bronchoalveolar lavage with evaluation of lung inflammatory cells was performed in all individuals at baseline and 24 h after allergen challenge. The expression of CD80 and CD86 costimulatory molecules by alveolar macrophages was studied and, in parallel, the efficiency of antigen presentation was measured in terms of IL-4 and IL-5 production by allergen-stimulated autologous T cells. We found that in asthmatic subjects (i) the percent of CD80+, but not CD86+ alveolar macrophages was increased at baseline and did not change following allergen challenge; (ii) CD86, but not CD80, membrane expression was up-regulated following allergen challenge; (iii) both CD80 and CD86 were required to support Th2 cytokine production by allergen-specific T cells, with a prevalent role of CD86 after allergen challenge. Our data indicate that alveolar macrophages deliver costimulatory signals via CD80 and CD86, which support the production of Th2 cytokines by allergen-specific T cells. They also indicate that CD86 in vivo is up-regulated in the 24 h following allergen exposure and that this modulation is functionally relevant.

Genetics of allergen-induced asthma

Antigen-induced airway hyperresponsiveness and airway inflammation are features of both human asthma and animal models of this disease. The genesis of these key asthma phenotypes represents the summation of a complex cascade of immune responses. It is hypothesized that multiple cell types are involved in the induction, propagation, and maintenance of these immune processes. Several molecules have been reported to be essential for cell-cell interactions, inflammatory cell recruitment, and effector functions leading to the overall expression of the asthmatic phenotype. This review summarizes the genetic evidence supporting a role for these molecules in antigen-driven airway hyperresponsiveness and inflammation.

Understanding the pathogenesis of allergic asthma using mouse models

OBJECTIVE

This paper reviews the current views of the pathogenesis of airway eosinophilic inflammation and airway hyperresponsiveness (AHR) in allergic asthma based on mouse models of the disease. The reader will also encounter new treatment strategies that have arisen as this knowledge is applied in practice.

DATA SOURCES

MEDLINE searches were conducted with key words asthma, mouse model, and murine. Additional articles were identified from references in articles and book chapters.

STUDY SELECTION

Original research papers and review articles from peer-reviewed journals were chosen.

RESULTS

Although the mouse model does not replicate human asthma exactly, the lessons learned about the pathogenesis of allergic airway inflammation and AHR are generally applicable in humans. Type 2 T helper lymphocytes (Th2) orchestrate the inflammation and are crucial for the development of AHR. Cells and molecules involved in T cell activation (dendritic cells, T cell receptor, major histocompatibility complex molecule, and costimulatory molecules) are also vital. Besides these, no other cell or molecule could be shown to be indispensable for the establishment of the model under all experimental conditions. There are at least three pathways that lead to AHR. One is dependent on immunoglobulin E and mast cells, one on eosinophils and interleukin-5 (IL-5), and one on IL-13. Eosinophils are probably the most important effector cells of AHR. Radical methods to treat asthma have been tested in the animal model, including modifying the polarity of lymphocyte response and antagonizing IL-5.

CONCLUSIONS

AHR, the hallmark of asthma, is attributable to airway inflammation ultimately mediated by helper T cells via three pathways, at least. The mouse model is also a valuable testing ground for new therapies of asthma.

Determinants of the immune-inflammatory response in allergic airway inflammation: overview of antigen presentation and cellular activation

Under normal circumstances the lung is in a state of immunologic homeostasis, a condition in which exposure to innocuous antigens does not lead to immune-inflammatory responses. This is the only reasonable solution to the dilemma faced by the lung: The need to interact with the external environment and the need to avoid responding to most of the environmental antigens to which it is exposed. In allergic diseases, such as asthma, this homeostasis is undermined, and immuneinflammatory responses to harmless aeroallergens are activated. We describe the changes in antigen presentation and cellular activation observed in a model of allergic airway inflammation. Further, we present a summary of our work that investigated the impact of the airway cytokine microenvironment on the development of immune responses in the respiratory tract.