CpG Oligodeoxynucleotide Inhibits Cockroach-Induced Asthma via Induction of IFN-γ⁺ Th1 Cells or Foxp3⁺ Regulatory T Cells in the Lung

Oligodeoxynucleotides containing CpG motifs (CpG-ODN) restores immune regulatory functions of airway macrophages of patients with asthma

Allergic asthma is characterized by the polarization of Th2 cells and impaired immune regulation. Macrophages occupy the largest proportion of airway immune cells. This study aims to discover the mechanism that hinders the immune regulatory functions of airway macrophages. In this study, macrophages were isolated from cells in bronchoalveolar lavage fluids (BALF) collected from asthma patients and normal control (NC) subjects. The results indicated that macrophages occupied the largest portion of the cellular components in BALF. The frequency of IL-10+ macrophage was significantly lower in asthma patients than in NC subjects. The expression of IL-10 in macrophages of BALF was associated with the levels of asthma-related parameters. The immune-suppressive functions of BALF M0 cells were defective in asthma patients. The inducibility of IL-10 expression was impaired in BALF macrophages of asthma patients, which could be restored by exposing to CpG. In conclusion, the induction of IL-10 in macrophages of BALF in asthma patients was impaired, and it could be restored by exposure to CpG.

Interplay of IL-33 and IL-35 Modulates Th2/Th17 Responses in Cigarette Smoke Exposure HDM-Induced Asthma

Cigarette smoke (CS) facilitates adverse effects on the airway inflammation and treatment of asthma. Here, we investigated the mechanisms by which CS exacerbates asthma. The roles of IL-33 and IL-35 in asthma development were examined by treatment with IL-33 knockout (IL-33 KO) or transfection of adenovirus encoding IL-35 (Ad-IL-35) in a murine model of cigarette smoke-exposure asthma. Furthermore, the involvement of IL-33 and IL-35 in regulating DCs and Th2/Th17 cells was examined in a coculture system of DCs with CD4+ T cells. Additionally, we observed the effect of CpG-ODNs on the balance of IL-33 and IL-35. We show that CS and house dust mite (HDM) exposure induced IL-33 and suppressed IL-35 levels in cigarette smoke-exposure asthma in vivo and in vitro. Treatment with IL-33 KO or Ad-IL-35 significantly attenuated airway hyperreactivity, goblet hyperplasia, airway remodelling, and eosinophil and neutrophil infiltration in the lung tissues from asthmatic mice. Furthermore, we demonstrated reciprocal regulation between CS and HDM-modulated IL-33 and IL-35. Mechanistically, IL-33 KO (or anti-ST2) and Ad-IL-35 attenuated Th2- and Th17-associated inflammation by downregulating TSLP-DC signalling. Finally, administration of CpG-ODNs suppressed the expression of IL-33/ST2 and elevated the levels of IL-35, which is mainly derived from CD4+Foxp+ Tregs, to alleviate Th2- and Th17-associated inflammation by inhibiting the activation of BMDCs. Taken together, the IL-33/ST2 pathway drives the DC-Th2 and Th17 responses of cigarette smoke-exposure asthma, while IL-35 has the opposite effect. CpG-ODNs represent a potential therapeutic strategy for modulating the balance of IL-33 and IL-35 to suppress allergic airway inflammation.

The Use of Chitosan Nanoparticles for Delivery of CpG ODN in Treatment of Allergic Balb/C Mice

Background

This study aims to prepare high stability chitosan nanoparticles (CNP) and examine the ability of CNP in CpG-ODN delivery when treating allergic mice model.

Methods

Preparation and characterization of CNP were performed by ionic gelation, dynamic light scattering, and zeta sizer. The CNP cytotoxicity and activation ability of CpG ODN delivered with CNP were tested using a cell counting kit-8 and Quanti blue method. Allergic mice were injected intraperitoneal with 10 ug ovalbumin on day 0 and 7, and then treated with intranasal CpG ODN/CpG ODN, delivered with CNP/CNP, on the third week three times per week for three weeks. The ELISA method measured cytokine and IgE profiles in the allergic mice's plasma and spleen.

Results

CNP results have sizes 27.73 nm±3.67 dan 188.23 nm±53.47, spherical in shape and non-toxic, and did not alter the NF-κB activation of CpG ODN in RAW-blue cells. The application of CpG ODN delivered by chitosan nanoparticles shows no statistical difference between groups of IFN-γ, IL-10, and IL-13 in Balb/c mice's plasma and spleen, in contrast with IgE level.

Conclusions

The results showed that using chitosan nanoparticles as a delivery system for CpG ODN has the potency to safely CpG ODN efficacy.

Construction and expression of Mycobacterium tuberculosis fusion protein AR2 and its immunogenicity in combination with various adjuvants to form vaccine

Tuberculosis (TB) is recognized as a highly infectious disease worldwide, and Bacille Calmette-Guerin (BCG) remains the only TB vaccine licensed for clinical use. As there is little evidence that BCG is effective in adults, there is an urgent need for a safe and effective vaccine to control TB in adults. In this study, we tested the immunomodulatory efficiency of the fusion protein AR2. whole blood IFN-γ release assay (WBIA) was used to detect antigen specificity. The immunogenicity of the vaccine was tested in C57BL/6 mice, and confirmed by enzyme-linked immunosorbent assay (ELISA), flow cytometry, and qRT-PCR. The fusion protein AR2 was successfully constructed and expressed. The level of IFN-γ in the peripheral blood of subjects stimulated by AR2 was significantly higher than in those induced by all subcomponent proteins. AR2-specific IgG and the Th1 cytokines IFN-γ, TNF-α, and iNOS were significantly increased in the group treated with the fusion protein and compound adjuvant (AR2+DMC). Likewise, the number of IFN-γ⁺ CD4⁺, IFN-γ⁺CD8⁺, and IL-4⁺ CD8⁺ T lymphocytes increased significantly. The combination of the fusion protein and the compound adjuvant (AR2+DMC) may be a suitable candidate for an enhanced TB vaccine. This study provides theoretical and experimental support for future research to enhance the effectiveness of TB vaccines and provides an experimental basis for evaluating the influence of different adjuvants on vaccine efficacy.

Use of protective antigen of Bacillus anthracis as a model recombinant antigen to evaluate toll-like receptors 2, 3, 4, 7 and 9 agonists in mice using established functional antibody assays, antigen-specific antibody assays and cellular assays

Toll-like receptor (TLR) agonists can act as immune stimulants alone or as part of alum or oil formulations. Humoral and cellular immune responses were utilized to assess quantitative and qualitative immune response enhancement by TLR agonists using recombinant protective antigen (rPA) of B. anthracis as a model antigen. To rPA, combined with aluminum hydroxide (Alhydrogel; Al(OH)3) or squalene (AddaVax™), was added one of 7 TLR agonists: TLR2 agonist Pam3CysSK4 (PamS), TLR3 agonist double stranded polyinosinic:polycytidylic acid (PolyIC), TLR4 agonists Monophosphoryl lipid A (MPLA) or glucopyranosyl lipid A (GLA), TLR7-8 agonists 3M-052 or Resiquimod (Resiq), or TLR9 agonist CPG 7909 (CPG). CD-1 or BALB/c mice received two intraperitoneal or intramuscular immunizations 14 days apart, followed by serum or spleen sampling 14 days later. All TLR agonists except PamS induced high levels of B. anthracis lethal toxin-neutralizing antibodies and immunoglobulin G (IgG) anti-PA. Some responses were >100-fold higher than those without a TLR agonist, and IP delivery (0.5 mL) induced higher TLR-mediated antibody response increases compared to IM delivery (0.05 mL). TLR7-8 and TLR9 agonists induced profound shifts of IgG anti-PA response to IgG2a or IgG2b. Compared to the 14-day immunization schedule, use of a shortened immunization schedule of only 7 days between prime and boost found that TLR9 agonist CPG in a squalene formulation maintained higher interferon-γ-positive cells than TLR4 agonist GLA. Variability in antibody responses was lower in BALB/c mice than CD-1 mice but antibody responses were higher in CD-1 mice. Lower serum 50% effective concentration (EC50) values were found for rPA-agonist formulations and squalene formulations compared to Al(OH)3 formulations. Lower EC50 values also were associated with low frequency detection of linear peptide epitopes. In summary, TLR agonists elicited cellular immune responses and markedly boosted humoral responses.

CpG Oligodeoxynucleotides Attenuate OVA-Induced Allergic Airway Inflammation via Suppressing JNK-Mediated Endoplasmic Reticulum Stress

Purpose

CpG-ODN has been found to attenuate allergic airway inflammation in our previous study. Here, we aimed to further investigate whether CpG-ODN exerts such effect via regulating endoplasmic reticulum (ER) stress and revealed the underlying mechanism.

Methods

Five-week-old C57BL/6 mice were randomly grouped and treated with or without CpG-ODN or/and SP600125. Meantime, RAW264.7 cells were used to investigate the effect of CpG-ODN on OVA-induced ER stress in vitro. The cellularity of bronchoalveolar lavage fluid (BALF) was classified and counted after Wright-Giemsa staining. HE and PAS staining methods were applied to analyze airway inflammation. The protein levels of IL-4, IL-5, IL-13, p-JNK, JNK, CHOP, XBP1, ATF6α and GRP78 in lung tissues were detected by Western blotting. Correspondingly, the ER stress markers were detected by Western blotting and immunofluorescence in RAW264.7 cells.

Results

In OVA-induced allergic airway inflammation, CpG-ODN significantly suppressed inflammatory cells infiltration, goblet cell hyperplasia and the protein expression of Th2 cytokines. Moreover, OVA exposure strongly increased the activation of ER stress with higher protein expressions of CHOP, XBP1, ATF6α and GRP78. However, these OVA-induced increase of ER stress markers were markedly suppressed by CpG-ODN treatment. In addition, exposure to OVA significantly increased the phosphorylation of JNK, which was significantly reduced by CpG-ODN treatment. Remarkably, single treatment of SP600125, an antagonist of JNK, functioned similarly as CpG-ODN in mitigating allergic airway inflammation and suppressing OVA-induced activation of ER stress; however, no significant synergistic effect was evidenced by combined treatment of SP600125 and CpG-ODN. Furthermore, in OVA-stimulated RAW264.7 cells, we also found that OVA stimulation increased the expressions of ER stress markers, and CpG-ODN significantly reduced their expression levels via suppressing the phosphorylation of JNK.

Conclusion

These results indicated that CpG-ODN mitigates allergic airway inflammation via suppressing the activation of JNK-medicated ER stress.

CpG Adjuvant in Allergen-Specific Immunotherapy: Finding the Sweet Spot for the Induction of Immune Tolerance

Prevalence and incidence of IgE-mediated allergic diseases have increased over the past years in developed and developing countries. Allergen-specific immunotherapy (AIT) is currently the only curative treatment available for allergic diseases that has long-term efficacy. Although AIT has been proven successful as an immunomodulatory therapy since its beginnings, it still faces several unmet needs and challenges today. For instance, some patients can experience severe side effects, others are non-responders, and prolonged treatment schedules can lead to lack of patient adherence and therapy discontinuation. A common strategy to improve AIT relies on the use of adjuvants and immune modulators to boost its effects and improve its safety. Among the adjuvants tested for their clinical efficacy, CpG oligodeoxynucleotide (CpG-ODN) was investigated with limited success and without reaching phase III trials for clinical allergy treatment. However, recently discovered immune tolerance-promoting properties of CpG-ODN place this adjuvant again in a prominent position as an immune modulator for the treatment of allergic diseases. Indeed, it has been shown that the CpG-ODN dose and concentration are crucial in promoting immune regulation through the recruitment of pDCs. While low doses induce an inflammatory response, high doses of CpG-ODN trigger a tolerogenic response that can reverse a pre-established allergic milieu. Consistently, CpG-ODN has also been found to stimulate IL-10 producing B cells, so-called B regulatory cells (Bregs). Accordingly, CpG-ODN has shown its capacity to prevent and revert allergic reactions in several animal models showing its potential as both preventive and active treatment for IgE-mediated allergy. In this review, we describe how CpG-ODN-based therapies for allergic diseases, despite having shown limited success in the past, can still be exploited further as an adjuvant or immune modulator in the context of AIT and deserves additional attention. Here, we discuss the past and current knowledge, which highlights CpG-ODN as a potential adjuvant to be reevaluated for the enhancement of AIT when used in appropriate conditions and formulations.

TLR9 and COVID-19: A Multidisciplinary Theory of a Multifaceted Therapeutic Target

By mapping the clinical pathophysiology of the novel coronavirus disease 2019 (COVID-19) against insights from virology, immunology, genomics, epidemiology and pharmacology, it is here proposed that the pathogen recognition receptor called toll like receptor 9 (TLR9) might have a pivotal role in the pathogenesis of COVID-19. Severe Acute Respiratory Syndrome Coronavirus 2, is causing the greatest global social and economic disruption since world war II. Lack of a vaccine, lack of successful treatment and limitations of the healthcare workforce and resources needed to safeguard patients with severe COVID-19 on the edge of life, demands radical preventive measures. It is urgently needed to identify biomarkers and drug candidates so that vulnerable individuals can be recognized early and severe multi-organ complications can be prevented or dampened. The TLR9 COVID-19 hypothesis describes a mechanism of action that could explain a wide spectrum of manifestations observed in patients with severe COVID-19. The introduced hypothesis proposes biomarkers for identification of vulnerable individuals and positions TLR9 as a promising multifaceted intervention target for prevention and/or treatment of COVID-19. TLR9 agonists might have value as prophylactic vaccine adjuvants and therapeutic immune stimulators at the early onset of disease. Additionally, in this current manuscript it is proposed for the first time that TLR9 could be considered as a target of "inhibition" aimed to dampen hyperinflammation and thrombotic complications in vulnerable patients that are at risk of developing late stages of COVID-19. The readily availability of TLR9 modulating drug candidates that have reached clinical testing for other disorders could favor a fast track development scenario, an important advantage under the current high unmet medical need circumstances regarding COVID-19.

Toll-Like Receptor Agonists as Adjuvants for Allergen Immunotherapy

Toll-like receptors (TLRs) are essential components of innate immunity and provide defensive inflammatory responses to invading pathogens. Located within the plasma membranes of cells and also intracellular endosomes, TLRs can detect a range of pathogen associated molecular patterns from bacteria, viruses and fungi. TLR activation on dendritic cells can propagate to an adaptive immune response, making them attractive targets for the development of both prophylactic and therapeutic vaccines. In contrast to conventional adjuvants such as aluminium salts, TLR agonists have a clear immunomodulatory profile that favours anti-allergic T lymphocyte responses. Consequently, the potential use of TLRs as adjuvants in Allergen Immunotherapy (AIT) for allergic rhinitis and asthma remains of great interest. Allergic Rhinitis is a Th2-driven, IgE-mediated disease that occurs in atopic individuals in response to exposure to otherwise harmless aeroallergens such as pollens, house dust mite and animal dander. AIT is indicated in subjects with allergic rhinitis whose symptoms are inadequately controlled by antihistamines and nasal corticosteroids. Unlike anti-allergic drugs, AIT is disease-modifying and may induce long-term disease remission through mechanisms involving upregulation of IgG and IgG4 antibodies, induction of regulatory T and B cells, and immune deviation in favour of Th1 responses that are maintained after treatment discontinuation. This process takes up to three years however, highlighting an unmet need for a more efficacious therapy with faster onset. Agonists targeting different TLRs to treat allergy are at different stages of development. Synthetic TLR4, and TLR9 agonists have progressed to clinical trials, while TLR2, TLR5 and TLR7 agonists been shown to have potent anti-allergic effects in human in vitro experiments and in vivo in animal studies. The anti-allergic properties of TLRs are broadly characterised by a combination of enhanced Th1 deviation, regulatory responses, and induction of blocking antibodies. While promising, a durable effect in larger clinical trials is yet to be observed and further long-term studies and comparative trials with conventional AIT are required before TLR adjuvants can be considered for inclusion in AIT. Here we critically evaluate experimental and clinical studies investigating TLRs and discuss their potential role in the future of AIT.

TLR9-IL-2 axis exacerbates allergic asthma by preventing IL-17A hyperproduction

Allergic asthma is one of most famous allergic diseases, which develops lung and airway inflammation. Recent studies have revealed the relationship between the pathology of allergic asthma and the increase of host-derived DNA in inflamed lung, but the role of the DNA-recognizing innate immune receptor for the inflammation is unknown well. Here we investigated the role of Toll-Like Receptor 9 in the pathogenesis of allergic asthma without synthesized CpG-ODNs. To examine that, we analyzed the pathology and immunology of house-dust-mite (HDM)-induced allergic asthma in Tlr9^–/– mice and TLR9-inhibitory-antibody-treated mice. In Tlr9^–/– mice, airway hyperresponsiveness (AHR) and the number of eosinophils decreased, and production of the Th2 cytokines IL-13, IL-5, and IL-4 was suppressed, compared with in wild-type mice. Interestingly, unlike Th2 cytokine production, IL-17A production was increased in Tlr9^–/– mice. Furthermore, production of IL-2, which decreases IL-17A production, was reduced in Tlr9^–/– mice. Blockade of TLR9 by treatment with TLR9-inhibitory-antibody, NaR9, effectively suppressed the development of allergic asthma pathology. IL-17A production in NaR9-treated mice was enhanced, which is comparable to Tlr9^-/- mice. These results suggest that the TLR9–IL-2 axis plays an important role in Th2 inflammation by modulating IL-17A production in HDM-induced allergic asthma and that targeting of TLR9 might be a novel therapeutic method for allergic asthma.

Airway inflammation and remodeling of cigarette smoking exposure ovalbumin-induced asthma is alleviated by CpG oligodeoxynucleotides via affecting dendritic cell-mediated Th17 polarization

Cigarette smoking (CS) is common in asthma, aggravating inflammatory reactions. However, the current treatment strategies for asthma are still not effective enough, and novel therapeutic approaches are required for CS-induced asthmatic disorders. We here investigated the ability of CpG oligodeoxynucleotides (CpG-ODNs) to inhibit airway inflammation and remodeling in ovalbumin (OVA)-associated asthma in mice exposed to chronic CS, revealing potential mechanistic insights. Lung tissue specimens were histologically analyzed. Th1/Th2/Th17 associated cytokines in serum, bronchoalveolar lavage fluid (BALF), and lung specimens were quantitated by ELISA, qRT-PCR and immunoblot. Parameters of bone marrow-derived dendritic cells (BMDCs) functions were evaluated as well. The results showed that BALB/c mice after CS and OVA treatments developed an asthmatic phenotype with airway inflammation involving both eosinophils and neutrophils, goblet cell metaplasia, airway remodeling, and elevated OVA-specific serum IgE, serum IL-17A, and BALF Th17/Th2 associated cytokines. CpG-ODNs and budesonide were found to synergistically inhibit inflammatory cell recruitment in the lung, airway remodeling, IgE synthesis, and Th17/Th2 associated cytokines. Mechanistically, CpG-ODNs and budesonide acted synergistically on BMDCs via downregulation of TSLP receptor (TSLPR) and IL-23 production, and subsequently contributed to dampen Th17/Th2 polarization in CS-associated asthma. In conclusion, combined administration of CpG-ODNs and budesonide, in a synergistic manner, inhibits airway inflammation, and tissue remodeling mediated by BMDCs by regulating IL-23 secretion and blocking TSLP signaling, which subsequently contribute to alleviate Th17/Th2 imbalance in CS-associated asthma.

Melatonin biosynthesis restored by CpG oligodeoxynucleotides attenuates allergic airway inflammation via regulating NLRP3 inflammasome

AIMS

Both CpG oligodeoxynucleotide (CpG-ODN) and melatonin have been reported to induce Th1 response and contribute to allergic asthma resistance. Here, we aimed to reveal how they confer such effect as well as whether they crosstalk with each other.

MAIN METHODS

Six-week-old Female C57BL/6 mice were challenged by OVA to induce allergic airway inflammation, and were treated with CpG-ODN, CpG-ODN plus Luzindole or melatonin respectively. Bronchoalveolar lavage fluid (BALF) cellularity was classified and counted by Wright's-Giemsa staining. HE and PAS staining were used to analyze airway inflammation. The levels of IL-4, IL-5, IL-13,GM-CSF and IFN-γ, as well as IL-1β and IL-18 were analyzed by ELISA. Protein expressions of ASMT, AANAT, NLRP3, IL-1β and caspase-1 in lung tissue were detected by Western blotting, expression of ASMT and AANAT were further observed by immunohistochemistry.

KEY FINDINGS

We found that CpG-ODN considerably suppressed OVA-induced airway leukocytes infiltration, goblet cell hyperplasia and Th2 cytokines production. Furthermore, the resolution effect of CpG-ODN on OVA-induced allergic airway inflammation occurred in parallel with decreased-activation of NLRP3 inflammasome and increased biosynthesis of melatonin. Blocking the effect of endogenous melatonin by Luzindole abolished the suppressive effect of CpG-ODN on OVA-induced airway inflammation and activation of NLRP3 inflammasome, suggesting such effect was mediated by endogenous melatonin. Moreover, exogenous melatonin pronouncedly ameliorated airway inflammation and decreased the activation of NLRP3 inflammasome.

SIGNIFICANCE

These results proven that CpG-ODN protects against allergic airway inflammation via suppressing the activation of NLRP3 inflammasome, and such effect may be resulted from the restored-production of melatonin.

TLR9 agonist adsorbed to alum adjuvant prevents asthma-like responses induced by Blomia tropicalis mite extract

Blomia tropicalis mite is highly prevalent in tropical and subtropical regions and it is associated with allergic diseases such as rhinitis and asthma. By using an OVA-model of allergic lung disease, we have previously shown that sensitization in the presence of toll like receptors (TLRs) agonists attenuates subsequent OVA-induced allergic responses. Here, we evaluated the effect of CpG-ODN, a specific synthetic TLR-9 agonist, on the development of experimental asthma induced by Blomia tropicalis extract, a relevant source of aeroallergens. Among different protocols of Blomia tropicalis extract sensitization, the subcutaneous sensitization in the presence of alum adjuvant induced the highest Th2 responses, including high IgE levels. Adsorption of CpG to Blomia tropicalis extract/Alum attenuated the airway hyperreactivity, the infiltration of inflammatory cells including eosinophils, and the IL-5 content in BAL. In addition, lung peribronchial inflammatory infiltrate, mucus production and IL-5-producing CD3⁺ CD4⁺ T cells were significantly reduced in the Blomia tropicalis extract/Alum+CpG group. Importantly, CpG inhibited total IgE production as well as active systemic or cutaneous anaphylaxis reactions. Inhibition of pulmonary Th2 responses was associated with increased IL-10 production but not with IFN-γ production. Notably, in IL-10-deficient mice, sensitization with OVA/Alum+CpG resulted in intense lung neutrophilia and IFN-γ production, indicating that IL-10 is necessary to inhibit subsequent Th1 immunity. Our work highlights the mechanisms of allergy attenuation by CpG and it indicates the potential use of Alum-based formulation with CpG to treat allergic processes.

Toll-like receptor 9-dependent interferon production prevents group 2 innate lymphoid cell-driven airway hyperreactivity

BACKGROUND

Group 2 innate lymphoid cells (ILC2s) are important mediators of allergic asthma. Bacterial components, such as unmethylated CpG DNA, a Toll-like receptor (TLR) 9 agonist, are known to possess beneficial immunomodulatory effects in patients with T cell-mediated chronic asthma. However, their roles in regulating ILC2s remain unclear.

OBJECTIVE

We sought to determine the role of TLR9 activation in regulating ILC2 function and to evaluate the therapeutic utility of an immunomodulatory microparticle containing natural TLR9 ligand (MIS416).

METHODS

We evaluated the immunomodulatory effects of CpG A in IL-33-induced airway hyperreactivity (AHR) and airway inflammation. The roles of interferons were examined in vivo and in vitro by using signal transducer and activator of transcription 1 (Stat1)^-/- mice and neutralizing antibodies against IFN-γ and IFN-α/β receptor subunit 1, and their cellular sources were identified. The therapeutic utility of MIS416 was investigated in the Alternaria alternata model of allergic asthma and in humanized NSG mice.

RESULTS

We show that TLR9 activation by CpG A suppresses IL-33-mediated AHR and airway inflammation through inhibition of ILC2s. Activation of TLR9 leads to production of IFN-α, which drives IFN-γ production by natural killer cells. Importantly, IFN-γ is essential for TLR9-driven suppression, and IFN-α cannot compensate for impaired IFN-γ signaling. We further show that IFN-γ directly inhibits ILC2 function through a STAT1-dependent mechanism. Finally, we demonstrate the therapeutic potential of MIS416 in A alternata-induced airway inflammation and validated these findings in human subjects.

CONCLUSION

TLR9 activation alleviates ILC2-driven AHR and airway inflammation through direct suppression of cell function. Microparticle-based delivery of TLR9 ligands might serve as a therapeutic strategy for asthma treatment.

Nucleic Acid Sensing in Allergic Disorders

Recent advances indicate that there is crosstalk between allergic disorders and nucleic acid sensing. Triggers that activate inflammatory mechanisms via nucleic acid sensors affect both allergic phenotypes and anti-viral responses, depending on the timing and the order of exposure. Viral respiratory infections, such as those caused by the rhinovirus, influenza, and respiratory syncytial virus, are the most frequent cause of significant asthma exacerbations through effects mediated predominantly by TLR3. However, agonists of other nucleic acid sensors, such as TLR7/8 and TLR9 agonists, may inhibit allergic inflammation and reduce clinical manifestations of disease. The allergic state can predispose the immune system to both exaggerated responses to viral infections or protection from anti-viral inflammatory responses. T_H2 cytokines appear to alter the epithelium, leading to defective viral clearance or exaggerated responses to viral infections. However, a T_H2 skewed allergic response may be protective against a T_H1-dependent inflammatory anti-viral response. This review briefly introduces the receptors involved in nucleic acid sensing, addresses mechanisms by which nucleic acid sensing and allergic responses can counteract one another, and discusses the strategies in experimental settings, both in animal and human studies, to harness the nucleic acid sensing machinery for the intervention of allergic disorders.

DNA and mRNA vaccination against allergies

Allergen-specific immunotherapy, which is performed by subcutaneous injection or sublingual application of allergen extracts, represents an effective treatment against type I allergic diseases. However, due to the long duration and adverse reactions, only a minority of patients decides to undergo this treatment. Alternatively, early prophylactic intervention in young children has been proposed to stop the increase in patient numbers. Plasmid DNA and mRNA vaccines encoding allergens have been shown to induce T helper 1 as well as T regulatory responses, which modulate or counteract allergic T helper 2-biased reactions. With regard to prophylactic immunization, additional safety measurements are required. In contrast to crude extracts, genetic vaccines provide the allergen at high purity. Moreover, by targeting the encoded allergen to subcellular compartments for degradation, release of native allergen can be avoided. Due to inherent safety features, mRNA vaccines could be the candidates of choice for preventive allergy immunizations. The subtle priming of T helper 1 immunity induced by this vaccine type closely resembles responses of non-allergic individuals and-by boosting via natural allergen exposure-could suffice for long-term protection from type I allergy.

Dental follicle mesenchymal stem cells down-regulate Th2-mediated immune response in asthmatic patients mononuclear cells

BACKGROUND

Asthma is a chronic inflammatory disease in which inflammatory responses have the polarisation of CD4⁺ T cells to Th2 cells. Dental follicle mesenchymal stem cells (DFSCs) have strong anti-inflammatory properties comparable to other mesenchymal stem cells.

OBJECTIVE

We investigated the immunomodulatory effects of DFSCs on CD4⁺ T helper cell responses of asthmatic patients and compared the results with those obtained with asthmatic subjects on immunotherapy and with healthy individuals.

METHOD

Peripheral blood mononuclear cells (PBMC) were isolated from immunotherapy naïve asthmatics, asthmatics on subcutaneous Der p1 immunotherapy and from healthy individuals. PBMC were pre-conditioned with anti-CD3/anti-CD28 mAbs, Der p1 or IFN-γ in the presence and absence of DFSCs and analysed for T cell viability and proliferation, CD4⁺ CD25⁺ FOXP3⁺ regulatory T cell frequencies, cytokine expression, and GATA3, T bet and FoxP3 expressions. Neutralisation of TGF-β and blockade of IDO and PGE2 pathways were performed to determine suppressive signalling pathways of DFSCs.

RESULTS

Dental follicle mesenchymal stem cells suppressed proliferative responses of CD4⁺ T lymphocytes and increased the frequency of Treg cells. DFSCs decreased effector and effector memory CD4⁺ T cell phenotypes in favour of naïve T cell markers. DFSCs decreased IL-4 and GATA3 expression and increased IFN-γ, T-bet and IL-10 expression in asthmatics. Costimulatory molecules were suppressed in monocytes with DFSCs in the cocultures. DFSCs down-regulated inflammatory responses via IDO and TGF-β pathways in asthmatic patients.

CONCLUSION

Dental follicle mesenchymal stem cells suppressed allergen-induced Th2-cell polarisation in favour of Th1 responses and attenuated antigen-presenting cell co-stimulatory activities. These studies suggest that DFSC-based cell therapy may provide pro-tolerogenic immunomodulation relevant to allergic diseases such as asthma.

Nanoparticle-based CpG-oligonucleotide therapy for treating allergic asthma

Allergic asthma is becoming increasingly prevalent in the developed world, and many common allergens are capable of inducing allergic asthma responses, particularly in atopic individuals. Unmethylated CpG-oligonucleotide (ODN) therapy can shift the immune response to mitigate these allergic responses. Therapeutic and prophylactic delivery of soluble CpG-ODN in preclinical studies has shown promise in treating existing asthma and preventing allergic responses upon subsequent allergen exposure, respectively. However, when CpG-ODN is coupled with nanoparticles or self assembled into nanostructures, improved efficacy of CpG-ODN treatment for several common allergens is observed in preclinical studies and clinical trials. Here we discuss the role of CpG-ODN in treating allergic asthma and how nanoparticle-based delivery can further enhance its therapeutic properties.

Treatment of allergic rhinitis with CpG oligodeoxynucleotides alleviates the lower airway outcomes of combined allergic rhinitis and asthma syndrome via a mechanism that possibly involves in TSLP

PURPOSE

Thymic stromal lymphopoietin (TSLP) is a critical regulator of immune responses associated with Th2 cytokine-mediated inflammation. Intranasal administration of oligodeoxynucleotides with CpG motifs (CpG-ODNs) might improve lower airway outcomes of combined allergic rhinitis and asthma syndrome (CARAS), but the inherent mechanisms of CpG-ODNs are not well defined. This study investigated whether CpG-ODNs treated to upper airway could reduce lower airway TSLP expression as well as whether this reduction could contribute to the alleviation of lower allergic inflammation and airway hyper-reactivity (AHR) in CARAS mice.

MATERIALS AND METHODS

Ovalbumin (OVA)-sensitized BALB/c mice were intranasal OVA exposure three times a week for 3 weeks. CpG-ODNs or an anti-TSLP mAb was administered to a subset of these mice 1 hour after intranasal OVA challenge, followed by 5 days of OVA aerosol challenge. The resulting immunological variables, nasal symptoms, and nasal mucosa and lung tissues pathology were evaluated. TSLP production in the lung tissues and bronchoalveolar lavage fluid (BALF) were determined by RT-PCR, western blotting or enzyme-linked immunosorbent assay.

RESULTS

The CARAS mice exhibited overexpression of TSLP in the lung tissues and BALF, and also demonstrated significant increases in BALF and splenocyte Th2-associated cytokine production, serum OVA-specific IgE, nose and lung pathologies, and AHR. Intranasal administration of CpG-ODNs restored TSLP in the lower airway, and it significantly reduced the following parameters: Th2-type cytokine production levels; the percentage of eosinophils in the BALF; IL-4 and IL-5 concentrations in the supernatants of cultured splenic lymphocytes; serum OVA-specific IgE; peribronchial inflammation score in the lungs; and nose pathology and nasal symptoms. Similar results were obtained when the CARAS mice were treated with an anti-TSLP mAb to block intranasal TSLP activity.

CONCLUSIONS

Treatment with intranasal CpG-ODNs improves lower airway immunological variable outcomes in the CARAS model via a mechanism that possibly involves in suppressing pulmonary TSLP-triggered allergic inflammation.

Outstanding animal studies in allergy I. From asthma to food allergy and anaphylaxis

PURPOSE OF REVIEW

Animal models published within the past 18 months on asthma, food allergy and anaphylaxis, all conditions of rising public health concern, were reviewed.

RECENT FINDINGS

While domestic animals spontaneously develop asthma, food allergy and anaphylaxis, in animal models, divergent sensitization and challenge routes, dosages, intervals and antigens are used to induce asthmatic, food allergic or anaphylactic phenotypes. This must be considered in the interpretation of results. Instead of model antigens, gradually relevant allergens such as house dust mite in asthma, and food allergens like peanut, apple and peach in food allergy research were used. Novel engineered mouse models such as a mouse with a T-cell receptor for house dust mite allergen Der p 1, or with transgenic human hFcγR genes, facilitated the investigation of single molecules of interest. Whole-body plethysmography has become a state-of-the-art in-vivo readout in asthma research. In food allergy and anaphylaxis research, novel techniques were developed allowing real-time monitoring of in-vivo effects following allergen challenge. Networks to share tissues were established as an effort to reduce animal experiments in allergy which cannot be replaced by in-vitro measures.

SUMMARY

Natural and artificial animal models were used to explore the pathophysiology of asthma, food allergy and anaphylaxis and to improve prophylactic and therapeutic measures. Especially the novel mouse models mimicking molecular aspects of the complex immune network in asthma, food allergy and anaphylaxis will facilitate proof-of-concept studies under controlled conditions.

Immunomodulatory Effects of Adjuvants CPG, MPLA, and BCG on the Derp2-Induced Acute Asthma at Early Life in an Animal Model of BALB/c Mice

The Th1- and Treg cell-related immune responses play key roles in the modulation of Th2 cell-related allergic disorders. The aim was to evaluate the effects of CPG, MPLA, and BCG on the number of Th1-, Th2-, and Treg cell-related parameters in an animal model of asthma. BALB/c mice were divided into five groups and immunized subcutaneously (SC) on days 1, 15, and 22 with allergen Derp2. Three groups of mice were pretreated SC on days 0, 14, and 21 with CPG, CPG + MPLA, or CPG + BCG. All mice were then challenged intranasally with Derp2 on days 28-37. Blood samples were collected from the retro-orbital sinus, on days 0, 23, and 40. The serum levels of IL-4, IFN-γ, IgE, and IgG2a were measured using ELISA technique. The blood number of Th1 and Treg cells was determined using flow cytometry. At the sensitization phase, the number of Th1 and the serum levels of IFN-γ and IgG2a were significantly increased in the Derp2-sensitized group pretreated with CPG plus MPLA, and the number of Treg cells was significantly elevated in Derp2-sensitized mice pretreated with CPG or CPG plus MPLA as compared with that in Derp2-sensitized control mice. At the challenge phase, the number of Th1 was significantly elevated in Derp2-sensitized mice pretreated with CPG plus MPLA, CPG plus BCG, or CPG; the count of Treg cells was significantly increased in Derp2-sensitized mice pretreated with CPG plus BCG group; and the levels of IFN-γ and IgG2a were significantly enhanced in the Derp2-sensitized group pretreated with CPG plus MPLA in comparison with those in Derp2-sensitized control mice. The scores of inflammation and mucus secretion in the lung were significantly decreased in the Derp2-sensitized group pretreated with CPG, BCG, and CPG plus MPLA in comparison with those in the Derp2-sensitized control group. These results showed that BCG, MPLA, and CPG modulate Th1-, Th2-, and Treg-related parameters and ameliorate lung inflammatory parameters in a mouse model of asthma.

CpG Type A Induction of an Early Protective Environment in Experimental Multiple Sclerosis

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory, demyelinating disease of the CNS that mimics human multiple sclerosis (MS), and it is thought to be driven by Th1 and Th17 myelin-reactive cells. Although adaptive immunity is clearly pivotal in the pathogenesis of EAE, with an essential role of CD4⁺ T cells, little is known of early, innate responses in this experimental setting. CpG-rich oligodeoxynucleotides (ODNs), typically found in microbial genomes, are potent activators of TLR9 in plasmacytoid dendritic cells (pDCs). In this study, we compared the effects of two types of CpG, namely, type A and type B, on EAE. We found that treatment with CpG type A ODN (CpG-A), known to induce high amounts of IFN-α in pDCs, significantly reduced disease severity in EAE, relative to controls (12.63 ± 1.86 versus 23.49 ± 1.46, resp.; p = 0.001). Treatment also delayed onset of neurological deficits and reduced spinal cord demyelination, while increasing the percentage of splenic regulatory (Foxp3⁺ CD4⁺) T cells. CpG-A likewise reduced the levels of IL-17 and IFN-γ in the CNS. Mechanistic insight into those events showed that CpG-A promoted a regulatory phenotype in pDCs. Moreover, adoptive transfer of pDCs isolated from CpG-A-treated mice inhibited CNS inflammation and induced disease remission in acute-phase EAE. Our data thus identify a link between TLR9 activation by specific ligands and the induction of tolerance via innate immunity mechanisms.

The effect of the TLR9 ligand CpG-oligodeoxynucleotide on the protective immune response to radiation-induced lung fibrosis in mice

CpG-oligodeoxynucleotide (CpG-ODN) is not only reported to protect against airway hyper responsiveness but is also known as a potent vaccine adjuvant for anti-tumor therapy. Little is known about the effect of CpG-ODN in mice with radiation-induced lung fibrosis (RILF), a common late stage form of tissue damage that occurs after thorax radiotherapy (RT). Here, we evaluated the immunomodulatory effects of CpG-ODN on the development of RILF. Mice were divided into four groups: (1) RT, single dose of 12Gy to the whole thorax; (2) CpG, only intraperitoneal injection of CpG-ODN for total 5 weeks; (3) RT+CpG, irradiation plus CpG-ODN treatment before and after irradiation for total 5 weeks; and (4) control (CTL): No RT or CpG-ODN treatment. In this study, we found that CpG-ODN treatment attenuated lung fibrosis and collagen deposition by increasing the number of M1 macrophagocytes, levels of Type-2 cytokines and TGF-β. CpG-ODN administration up-regulated the expression of TLR9 and STAT1 phosphorylation and reversed the expression of Type-2 immune response key transcription factor GATA-3. Activation of the JAK-STAT1 signaling pathway further enhanced M1 macrophage differentiation and Type-1 cytokine production. This study reveals the mitigating effect of early exposure to CpG-ODN on lung injury caused by irradiation in mice. The potential mechanism of action may be related to enhancement of Type-1 immunity. In conclusion, CpG-ODN may be a potential therapeutic target to treat RILF.