CD137 ligand prevents the development of T-helper type 2 cell-mediated allergic asthma by interferon-gamma-producing CD8+ T cells

Immune checkpoint molecules in prevention and development of asthma

Allergic asthma is a respiratory disease initiated by type-2 immune responses characterized by secretion of alarmins, interleukin-4 (IL-4), IL-5, and IL-13, eosinophilic inflammation, and airway hyperresponsiveness (AHR). Immune checkpoints (ICPs) are inhibitory or stimulatory molecules expressed on different immune cells, tumor cells, or other cell types that regulate immune system activation and maintain immune homeostasis. Compelling evidence indicates a key role for ICPs in both the progression and prevention of asthma. There is also evidence of asthma development or exacerbation in some cancer patients receiving ICP therapy. The aim of this review is to provide an updated overview of ICPs and their roles in asthma pathogenesis, and to assess their implications as therapeutic targets in asthma.

CD137: A checkpoint regulator involved in atherosclerosis

Inflammation is associated with atherosclerotic plaque development and precipitation of myocardial infarction and stroke, and anti-inflammatory therapy may reduce disease severity. Costimulatory molecules are key regulators of immune cell activity and inflammation, and are associated with disease development in atherosclerosis. Accumulating evidence indicates that a costimulatory molecule of the Tumor Necrosis Factor Receptor superfamily, the checkpoint regulator CD137, promotes atherosclerosis and vascular inflammation in experimental models. In light of the burgeoning consideration of CD137-targeted therapy in the clinic, it will be important to better understand costimulator immunobiology in development of cardiovascular disease. Here, we review available data on the costimulator CD137 and its potential role in atherosclerosis.

Protective effects of agonistic anti-4-1BB antibody on the development of imiquimod-induced psoriasis-like dermatitis in mice

Agonistic anti-4-1BB antibodies (Abs) play a central role in immunomodulatory conditions that control the pathogenesis of immune-mediated autoimmune and allergic diseases. However, the effects of agonistic anti-4-1BB Abs have not been examined in an experimental mouse model of psoriasis. Therefore, we investigated the protective effects of agonistic anti-4-1BB Abs, using imiquimod (IMQ)-induced psoriasis-like dermatitis in mice, a condition histologically and clinically similar to human psoriasis. We found that administration of agonistic anti-4-1BB Abs (10mg/kg) significantly alleviated the severity of IMQ-induced psoriasis-like skin inflammation in mice, with reduced histologic symptoms, including inflammatory infiltration, parakeratosis, and hyperkeratosis. Subsequent analyses revealed that the production of Th17 cytokines (IL-17A and IL-23) in the serum and skin of IMQ-induced mice was significantly inhibited by agonistic anti-4-1BB Abs (10mg/kg), although Th1 cytokines (TNF-α and IFN-γ) were not. Moreover, administration of agonistic anti-4-1BB Abs (10mg/kg) induced a relative increase of CD4(+)FoxP3(+) regulatory T (Treg) cells in the spleen and draining lymph node (DLN). Taken together, our data provide evidence that agonistic anti-4-1BB Abs possesses immunosuppressive properties in IMQ-induced psoriasis-like skin inflammation, providing insight into the immunomodulatory effect of agonistic anti-4-1BB Abs for psoriasis immunotherapy.

The pharmacology of second-generation chimeric antigen receptors

Second-generation chimeric antigen receptors (CARs) retarget and reprogramme T cells to augment their antitumour efficacy. The combined activating and co-stimulatory domains incorporated in these CARs critically determine the function, differentiation, metabolism and persistence of engineered T cells. CD19-targeted CARs that incorporate CD28 or 4-1BB signalling domains are the best known to date. Both have shown remarkable complete remission rates in patients with refractory B cell malignancies. Recent data indicate that CD28-based CARs direct a brisk proliferative response and boost effector functions, whereas 4-1BB-based CARs induce a more progressive T cell accumulation that may compensate for less immediate potency. These distinct kinetic features can be exploited to further develop CAR-based T cell therapies for a variety of cancers. A new field of immunopharmacology is emerging.

Critical role for syndecan-4 in dendritic cell migration during development of allergic airway inflammation

Syndecan-4 (SDC4), expressed on dendritic cells (DCs) and activated T cells, plays a crucial role in DC motility and has been shown as a potential target for activated T-cell-driven diseases. In the present study, we investigate the role of SDC4 in the development of T-helper 2 cell-mediated allergic asthma. Using SDC4-deficient mice or an anti-SDC4 antibody we show that the absence or blocking of SDC4 signalling in ovalbumin-sensitized mice results in a reduced asthma phenotype compared with control animals. Most importantly, even established asthma is significantly decreased using the anti-SDC4 antibody. The disturbed SDC4 signalling leads to an impaired motility and directional migration of antigen-presenting DCs and therefore, to a modified sensitization leading to diminished airway inflammation. Our results demonstrate that SDC4 plays an important role in asthma induction and indicate SDC4 as possible target for therapeutic intervention in this disease.

A dominant role for the methyl-CpG-binding protein Mbd2 in controlling Th2 induction by dendritic cells

Dendritic cells (DCs) direct CD4(+) T-cell differentiation into diverse helper (Th) subsets that are required for protection against varied infections. However, the mechanisms used by DCs to promote Th2 responses, which are important both for immunity to helminth infection and in allergic disease, are currently poorly understood. We demonstrate a key role for the protein methyl-CpG-binding domain-2 (Mbd2), which links DNA methylation to repressive chromatin structure, in regulating expression of a range of genes that are associated with optimal DC activation and function. In the absence of Mbd2, DCs display reduced phenotypic activation and a markedly impaired capacity to initiate Th2 immunity against helminths or allergens. These data identify an epigenetic mechanism that is central to the activation of CD4(+) T-cell responses by DCs, particularly in Th2 settings, and reveal methyl-CpG-binding proteins and the genes under their control as possible therapeutic targets for type-2 inflammation.

Lifetime-dependent effects of bisphenol A on asthma development in an experimental mouse model

BACKGROUND

Environmental factors are thought to contribute significantly to the increase of asthma prevalence in the last two decades. Bisphenol A (BPA) is a xenoestrogen commonly used in consumer products and the plastic industry. There is evidence and an ongoing discussion that endocrine disruptors like BPA may affect human health and also exert alterations on in the immune system. The aim of this study was to investigate age-dependent effects of BPA on the asthma risk using a murine model to explain the controversial results reported till date.

METHODS

BALB/c mice were exposed to BPA via the drinking water for different time periods including pregnancy and breastfeeding. To induce an asthma phenotype, mice were sensitized to ovalbumin (OVA), followed by an intrapulmonary allergen challenge.

RESULTS

BPA exposure during pregnancy and breastfeeding had no significant effect on asthma development in the offspring. In contrast, lifelong exposure from birth until the last antigen challenge clearly increased eosinophilic inflammation in the lung, airway hyperreactivity and antigen-specific serum IgE levels in OVA-sensitized adult mice compared to mice without BPA exposure. Surprisingly, BPA intake during the sensitization period significantly reduced the development of allergic asthma. This effect was reversed in the presence of a glucocorticoid receptor antagonist.

CONCLUSIONS

Our results demonstrate that the impact of BPA on asthma risk is strongly age-dependent and ranges from asthma-promoting to asthma-reducing effects. This could explain the diversity of results from previous studies regarding the observed health impact of BPA.

Therapeutic potential of the peptide leucine arginine as a new nonplant bowman-birk-like serine protease inhibitor

The peptide leucine arginine (pLR) belongs to a new class of cyclic peptides isolated from frog skin. Its primary sequence is similar to the reactive loop of plant Bowman-Birk inhibitors (BBI), and the recently discovered circular sunflower trypsin inhibitor-1 (SFTI-1). The conformational properties of pLR in solution were determined by NMR spectroscopy and revealed excellent structural similarity to BBI and SFTI-1. Moreover, pLR is a highly potent trypsin inhibitor, with Ki values in the nanomolar range, and, due to its small size, a potential inhibitor of the serine protease tryptase. Since tryptase plays a crucial role in the development of allergic airway inflammation, the therapeutic potential of pLR in a murine asthma model was investigated. Treatment of ovalbumin-sensitized mice with pLR during allergen challenge reduced the acute asthma phenotype. Most importantly, application even at the end of a long-lasting chronic asthma model decreased the development of chronic airway inflammation and tissue remodeling.

4-1BB ligand-mediated imbalance of helper 17 T cells and regulatory T cells in patients with allergic asthma

OBJECTIVES

To investigate the presence of 4-1BB ligand (4-1BBL) in the peripheral blood of patients with allergic asthma and evaluate its role in controlling the balance between helper 17 T (T(h)17) and regulatory T (T(reg)) cells.

METHODS

Soluble 4-1BBL (s4-1BBL) was quantified by enzyme-linked immunosorbent assay in plasma from patients with asthma (n = 45) and from healthy control subjects (n = 35). The proportion of monocytes positive for membrane-bound 4-1BBL (m4-1BBL) was determined by flow cytometry. Peripheral blood mononuclear cells from patients with asthma were incubated with anti-4-1BB monoclonal antibody in vitro. Concentrations of interleukin (IL)-17 and transforming growth factor (TGF)-β(1) in the culture supernatant were analysed.

RESULTS

Plasma s4-1BBL concentrations and the proportion of m4-1BBL-positive monocytes were significantly lower in patients with asthma than in control subjects. The culture supernatant concentration of TGF-β(1) was increased and that of IL-17 was decreased by incubation with anti-4-1BB monoclonal antibody.

CONCLUSIONS

Both soluble and membrane-bound 4-1BBL were reduced in patients with allergic asthma compared with control subjects. 4-1BBL/4-1BB signalling may play an important role in allergic asthma by regulating the T(h)17/T(reg) balance.

Anti-Asthma Simplified Herbal Medicine Intervention-induced long-lasting tolerance to allergen exposure in an asthma model is interferon-γ, but not transforming growth factor-β dependent

BACKGROUND

Chronic allergic asthma is the result of a T-helper type 2 (Th2)-biased immune status. Current asthma therapies control symptoms in some patients, but a long-lasting therapy has not been established. Anti-Asthma Simplified Herbal Medicine Intervention (ASHMI™), a Chinese herbal formula, improved symptoms and lung function, and reduced Th2 responses in a controlled trial of patients with persistent moderate to severe asthma.

OBJECTIVE

We evaluated the persistence of ASHMI™ beneficial effects following therapy in a murine model of chronic asthma and the immunological mechanisms underlying such effects. Methods BALB/c mice sensitized intraperitoneally with ovalbumin (OVA) received 3 weekly intratracheal OVA challenges to induce airway hyper-reactivity (AHR) and inflammation (OVA mice). Additionally, OVA mice were treated with ASHMI™ (OVA/ASHMI™) or water (OVA/sham) for 4 weeks, and then challenged immediately and 8 weeks post-therapy. In other experiments, OVA mice received ASHMI™ treatment with concomitant neutralization of IFN-γ or TGF-β. Effects on airway responses, cytokine- and OVA-specific IgE levels were determined 8 weeks post-therapy.

RESULTS

Before treatment, OVA mice exhibited AHR and pulmonary eosinophilic inflammation following OVA challenge, which was almost completely resolved immediately after completing treatment with ASHMI™ and did not re-occur following OVA re-challenge up to 8 weeks post-therapy. Decreased allergen-specific IgE and Th2 cytokine levels, and increased IFN-γ levels also persisted at least 8 weeks post-therapy. ASHMI™ effects were eliminated by the neutralization of IFN-γ, but not TGF-β, during therapy.

CONCLUSION

ASHMI™ induced long-lasting post-therapy tolerance to antigen-induced inflammation and AHR. IFN-γ is a critical factor in ASHMI™ effects.

CD137 ligand, a member of the tumor necrosis factor family, regulates immune responses via reverse signal transduction

CD137 (4-1BB, TNFR superfamily 9) and its ligand are members of the TNFR and TNF families, respectively, and are involved in the regulation of a wide range of immune activities. CD137 ligand cross-links its receptor, CD137, which is expressed on activated T cells, and costimulates T cell activities. CD137 ligand can also be expressed as a transmembrane protein on the cell surface and transmit signals into the cells on which it is expressed (reverse signaling). CD137 ligand expression is found on most types of leukocytes and on some nonimmune cells. In monocytic cells (monocytes, macrophages, and DCs), CD137 ligand signaling induces activation, migration, survival, and differentiation. The activities of T cells, B cells, hematopoietic progenitor cells, and some malignant cells are also influenced by CD137 ligand, but the physiological significance is understood only partly. As CD137 and CD137 ligand are regarded as valuable targets for immunotherapy, it is pivotal to determine which biological effects are mediated by which of the 2 molecules.

CD27 costimulation is not critical for the development of asthma and respiratory tolerance in a murine model

CD27 is a costimulatory molecule of the TNFR family strongly expressed on activated CD4(+) and CD8(+) T lymphocytes. Binding with its ligand CD70, present on lymphocytes and DCs, leads to enhanced T cell activation and proliferation. Several other costimulatory molecules of the TNFR family like CD30, CD134 (OX40) or CD137 (4-1BB) have been shown to be critically involved in the development of asthma and/or respiratory tolerance. However, the role of CD27/CD70 signalling in these disease models has not been studied intensively. The aim of this study was to directly investigate the role of CD27 for the development of asthma and respiratory tolerance by comparative analysis of wild type (WT) and CD27(-/-) mice in the corresponding murine models. Ovalbumin (OVA)-sensitized and challenged CD27(-/-) mice developed comparably increased airway hyperreactivity (AHR), eosinophilic airway inflammation, mucus hypersecretion and elevated OVA-specific serum IgE levels in response to OVA sensitization as WT mice. In addition, Th2 cytokine production in spleen cell culture supernatants and proliferation of splenocytes after in vitro OVA restimulation was equally enhanced when derived from WT and CD27(-/-) mice. Furthermore, the absence of CD27 had no decisive impact on tolerance induction, so that WT and CD27(-/-) mice were comparably protected from asthma development by mucosal antigen application before sensitization. Our results suggest that CD27 costimulation is dispensable for a Th2 cell mediated allergic asthma response and respiratory tolerance induction in murine models.

The role of costimulatory molecules in allergic disease and asthma

The prevalence of allergic diseases has increased rapidly in recent years. It is well established that the deleterious allergic response is initiated by T-cell recognition of major histocompatibility class II-peptide complexes at the surface of antigen-presenting cells. While this first signal gives antigen specificity to the adaptive immune response, a second nonspecific costimulatory signal is required by T cells to become fully activated. This signal is provided by interactions between antigen-presenting cells and T cells through molecules borne at the surfaces of the two cell types. Depending on the type of molecules involved, this secondary signal can promote the development of an inflammatory allergic reaction or may favor immune regulation. Several molecules of the B7 family (CD80, CD86, PD-1, ICOS, CTLA-4) and tumor necrosis factor receptor family (OX40, CD30, 4-1BB, Fas, CD27, CD40) play an important role in delivering costimulatory signals in early and late phases of allergic response. Therefore, costimulatory molecules involved in promotion or prevention of allergic immune responses are potential targets for the development of novel therapeutic approaches. This review aims to recapitulate our current understanding of the relationship between allergic diseases and costimulatory molecules.

Different role of CD30 in the development of acute and chronic airway inflammation in a murine asthma model

CD30 is a costimulatory molecule of the TNF receptor superfamily, expressed on activated T and B cells. Previously, we have shown in a murine asthma model the crucial role of CD30 signaling for the development of this Th2-cell-mediated disease. In the present study, we investigated the role of CD30 in the maintenance of the immune response. In contrast to the acute model, in the chronic model CD30(-/-) mice developed a severe asthma-like phenotype with eosinophilic inflammation and high serum IgE levels. Collagen content, ECM protein deposition and proliferation of smooth muscle cells as signs for airway remodeling were equally increased in both CD30(-/-) and WT mice. Reduced expression of the costimulatory molecule OX40 on CD3(+) T cells in the acute and up-regulation in the chronic model indirectly supported a compensatory role of OX40 for CD30 signaling. In accordance, application of agonistic OX40 antibody restored the asthma phenotype in CD30(-/-) mice in the acute model, whereas chronic airway inflammation was reduced in the presence of an inhibitory anti-OX40 ligand antibody. These data demonstrate that the crucial role of CD30 signaling in the development of acute asthma may be taken over by other costimulatory molecules like OX40 after long-term exposure to the antigen.

CD27 and CD70 do not play a critical role in the development of experimental allergic conjunctivitis in mice

CD27, which belongs to the TNF receptor family, is a costimulatory molecule that participates in T-cell activation. Unlike costimulatory molecules such as OX40 and 4-1BB, little is known about the role CD27 plays a role in the development of experimental diseases. We asked whether CD27 and its ligand CD70 participate in the development of experimental allergic conjunctivitis (EC) in BALB/c mice, which is generated by immunization with ragweed (RW) in alum and challenged 10 days later with RW in eye drops. The roles of CD27 and CD70 were tested by intraperitoneally injecting the mice with anti-CD27, anti-CD70 or a control Ab during the induction or effector phase. Twenty-four hours after challenge, the conjunctivas, blood and spleens were harvested for histological analysis, measuring Ig levels and cytokine analysis, respectively. Regardless of when the mice were treated, anti-CD27 or anti-CD70 Ab treatment did not significantly affect the severity of EC as evaluated by conjunctival eosinophil numbers. However, anti-CD27 or anti-CD70 Ab treatment during the induction phase did significantly modulate systemic humoral and cellular immune responses. In vitro treatment of RW-primed splenocytes with anti-CD27 or anti-CD70 Ab did not affect the EC-inducing capability of the splenocytes. Taken together, CD27 and CD70 do not play a critical role in the development of EC.