Strategies of mucosal immunotherapy for allergic diseases

Oral administration of Hsp65-producing Lactococcus lactis attenuates allergic asthma in a murine model

AIMS

Allergic asthma is a chronic inflammatory lung disease characterized by a Th2-type immune response pattern. The development of nonspecific immunotherapy is one of the primary goals for the control of this disease.

METHODS AND RESULTS

In this study, we evaluated the therapeutic effects of Lactococcus lactis-producing mycobacterial heat shock protein 65 (LLHsp65) in an ovalbumin (OVA)-induced allergic asthma model. OVA-challenged BALB/c mice were orally administrated with LLHsp65 for 10 consecutive days. The results demonstrate that LLhsp65 attenuates critical features of allergic inflammation, like airway hyperresponsiveness and mucus production. Likewise, the treatment decreases the pulmonary eosinophilia and the serum level of OVA-specific IgE. In addition to deviating immune responses towards Th1-cytokine profile, increase regulatory T cells, and cytokine levels, such as IL-6 and IL-10.

CONCLUSIONS

Our results reveal that the mucosal immunotherapy of LLHsp65 significantly reduces the overall burden of airway allergic inflammation, suggesting a promising therapeutic strategy for allergic asthma treatment.

SIGNIFICANCE AND IMPACT OF THE STUDY

This research reveals new perspectives on nonspecific immunotherapy based on the delivery of recombinant proteins by lactic acid bacteria to treat of allergic disorders.

New and old adjuvants in allergen-specific immunotherapy: With a focus on nanoparticles

Allergic diseases have remarkably increased in recent years. Nowadays, efforts for curing and management of these disorders are an important concern worldwide. Allergen-specific immunotherapy (ASIT) has recently gained more attention as a means for the management of allergic diseases. Adjuvants or helper agents are materials applied for better stimulating and shifting of protective responses, and these belong to an extremely diverse collection of complexes. The main function of adjuvants includes acting as depot foundations, transferring vehicles, and immunostimulators. Immunostimulatory adjuvants have gained increasing attention for ASIT. In this regard, the present study provides a review of old and new adjuvants used in allergen immunotherapy.

Modulating Shrimp Tropomyosin-Mediated Allergy: Hypoallergen DNA Vaccines Induce Regulatory T Cells to Reduce Hypersensitivity in Mouse Model

Shellfish allergy is one of the most common food allergies, with tropomyosin as the major cross-reactive allergen. However, no allergen-specific immunotherapy is clinically available. Recently, we designed two shrimp hypoallergens MEM49 and MED171. This study aimed to examine and compare the efficacy of the MEM49- and MED171-based DNA vaccines (pMEM49 and pMED171) in modulating shrimp allergy in a murine model of shrimp tropomyosin sensitivity. Intradermal immunization of BALB/c mice with pMEM49 or pMED171 effectively down-modulated allergic symptoms, tropomyosin-specific IgE levels, intestinal Th2 cytokines expression, and inflammatory cell infiltration. Both pMEM49 and pMED171 increased the frequency of regulatory T cells, but to a greater extent by pMED171 with upregulation of gut-homing molecules integrin-α4β7. The functionality of the pMED171-induced Treg cells was further illustrated by anti-CD25-mediated depletion of Treg cells and the adoptive transfer of CD4⁺CD25⁺Foxp3⁺Treg cells. Collectively, the data demonstrate that intradermal administration of pMED171 leads to the priming, activation, and migration of dermal dendritic cells which subsequently induce Treg cells, both locally and systemically, to downregulate the allergic responses to tropomyosin. This study is the first to demonstrate the potency of hypoallergen-encoding DNA vaccines as a therapeutic strategy for human shellfish allergy via the vigorous induction of functional Treg cells.

Pulmonary Administration of Soluble Antigen Arrays Is Superior to Antigen in Treatment of Experimental Autoimmune Encephalomyelitis

Antigen-specific immunotherapy has been used to hyposensitize patients to allergens and offers an enticing approach for attenuating autoimmune diseases. Applying antigen-specific immunotherapy to mucosal surfaces such as the lungs may engage unique immune response pathways to improve efficacy. Pulmonary delivery of soluble antigen arrays (SAgAs) was explored in mice with experimental autoimmune encephalomyelitis (EAE), a multiple sclerosis model. SAgAs were designed to impede immune response to autoantigen epitopes and are composed of a hyaluronan backbone with peptides PLP_139-151 (proteolipid protein) and LABL, a disease-causing proteolipid peptide epitope and an intracellular cell-adhesion molecule-1 ligand, respectively. Pulmonary instillation of SAgAs decreased disease score, improved weight gain, and decreased incidence of disease in EAE mice compared to pulmonary delivery of hyaluronic acid polymer, LABL, or PLP. Interestingly, treating with PLP alone also showed some improvement. Splenocytes from SAgA-treated animals showed increased interferon-gamma levels, and interleukin-6 (IL-6) and IL-17 were elevated in SAgA-treated animals compared to PLP treatments. IL-10, IL-2, and tumor necrosis factor-alpha levels showed no significant difference, yet trends across all cytokines suggested SAgAs induced a very different immune response compared to treatment with PLP alone. This work suggests that codelivery of peptide components is essential when treating EAE via pulmonary instillation, and the immune response may have shifted toward immune tolerance.

Preliminary Study on Gene Expression of Chitinase-Like Cytokines in Human Airway Epithelial Cell Under Chitin and Chitosan Microparticles Treatment

Small-sized chitin and chitosan microparticles (MPs) reduce allergic inflammation. We examined the capacity of these glycans to stimulate A549 human airway epithelial cells to determine the feasibility of using of these glycans as allergic therapeutic modality. A549 cells were treated with MPs and then expressions levels of chitinase domain-containing 1 (CHID1) and chitinase 3-like 1 (CHI3L1) genes were determined by quantitative real-time PCR. IL-6 production was measured by ELISA. Chitin MPs resulted in upregulation of CHI3L1 expression by 35.7-fold while mRNA expression did not change with chitosan MPs. Compared to the untreated group, production of IL-6 was significantly decreased in the chitosan MPs-treated group, but chitin MPs treatment cause elevation of IL-6 level. This study demonstrates that chitin potently induces CHI3L1 expression, but chitosan is relatively inert. This effect and inhibition of pro-inflammatory cytokine (IL-6) suggest that chitosan MPs may possess more potential for therapeutic uses in human airway allergic inflammation.

Mucosal immune tolerance at the ocular surface in health and disease

The ocular surface is constantly exposed to environmental irritants, allergens and pathogens, against which it can mount a prompt immune response to preserve its integrity. But to avoid unnecessary inflammation, the ocular surface's mucosal immune system must also discriminate between harmless and potentially dangerous antigens, a seemingly complicated task. Despite its unique features, the ocular surface is a mucosal lining, and as such, it shares some homeostatic and pathophysiological mechanisms with other mucosal surfaces. The purpose of this review is to explore the mucosal homeostatic immune function of the ocular surface in both the healthy and diseased states, with a special focus on mucosal immunology concepts. The information discussed in this review has been retrieved by PubMed searches for literature published from January 1981 to October 2016.

The effect of inhaled inactived Mycobacterium phlei as a treatment for asthma

Allergic asthma is a chronic airway disorder characterized by airway inflammation, mucus hypersecretion, and airway hyperresponsiveness (AHR). A murine model of asthma was used to examine the antiasthmatic effect of inhaled inactived Mycobacterium phlei (M. phlei). AHR, neutrophil levels, eosinophil levels and levels of interleukin (IL)-17 and IL-23 receptor (IL-23R) were monitored. The results demonstrated that inactivated M. phlei alleviates the IL-17+γδT cell-mediated immune response and attenuates airway inflammation and airway hyperresponsiveness in the asthmatic murine lung, partially through inhibiting the expression of IL-23R. In conclusion, inactivated M. phlei may be an effective antiasthmatic treatment, regulating IL-17-producing γδT (IL-17+γδT) cell-mediated airway inflammation and airway hyperresponsiveness to relieve the symptoms of mice with asthma.

The Use of Adjuvants for Enhancing Allergen Immunotherapy Efficacy

One key approach to increase the efficacy and the safety of immunotherapy is the use of adjuvants. However, many of the adjuvants currently in use can cause adverse events, raising concerns regarding their clinical use, and are geared toward productive immune responses but not necessarily tolerogenic responses. Thus, novel adjuvants for immunotherapy are needed and are being developed. Essential is their potential to boost appropriate tolerogenic adaptive immune responses to allergens while limiting side effects. This review provides an overview of adjuvants currently in clinical use or under development and discusses their therapeutic effect in enhancing allergen-induced tolerance.

Transgenic plants for allergen-specific immunotherapy

Allergen-specific immunotherapy (IT) is an effective treatment for allergic diseases. Although subcutaneous and sublingual ITs are currently used, safer, easier, and more effective IT is under development. Induction of immune tolerance by oral administration of allergen has been proven, though oral IT has not been applied clinically. It is mainly because a large amount of purified allergen is required to induce oral tolerance. To overcome this problem, plants, peculiarly rice, have been investigated as allergen vehicles for oral IT. Rice can store a considerable amount of expressed allergen in its seeds and the accumulated allergen is stable and resistant to gastrointestinal digestion. Therefore, we have developed transgenic rice seeds (Tg rice) in which major epitopes of cedar pollen or house dust mites are expressed. We are establishing Tg rice with demonstrated efficacy in murine models of allergic rhinitis and bronchial asthma by oral administration at practical doses. In addition, the amount, distribution, and allergenicity of the expressed allergen have been improved in our Tg rice. Rice-based oral IT is a promising new concept in IT for the treatment of allergic diseases.

HMGB1 contributes to allergen-induced airway remodeling in a murine model of chronic asthma by modulating airway inflammation and activating lung fibroblasts

The pro-inflammation factor high-mobility group box protein 1 (HMGB1) has been implicated in the pathogenesis of asthma. In this study, we used a murine model of chronic asthma to evaluate the effects of HMGB1 on airway remodeling. Female BALB/c mice were randomly divided into four groups: control, ovalbumin (OVA) asthmatic, OVA+isotype antibody and OVA+anti-HMGB1 antibody. Anti-HMGB1 antibody therapy was started on day 21 and was administered three times per week for 6 weeks before intranasal challenge with OVA. In this mouse model, HMGB1 expression is significantly elevated. The anti-HMGB1 antibody group exhibited decreased levels of immunoglobulin E (IgE) and inflammatory mediators and reduced inflammatory cell accumulation, airway hyperresponsiveness (AHR), mucus synthesis, smooth muscle thickness and lung collagen content compared with the OVA groups. Treatment with HMGB1 increased proliferation, migration, collagen secretion and α-smooth muscle actin (SMA) expression in MRC-5 cells. Treatment with the HMGB1/IL-1β complex significantly increased the expression and secretion of transforming growth factor (TGF-β1), matrix metalloproteinase (MMP)-9 and vascular endothelial growth factor (VEGF). Altogether, these results suggest that blocking HMGB1 activity may reverse airway remodeling by suppressing airway inflammation and modulating lung fibroblast phenotype and activation.

Effect of inhaled inactivated Mycobacterium phlei in children with moderate asthma

Bacillus Calmette-Guérin and other mycobacterial vaccines are important therapeutic methods in a series of chronic inflammatory disorders characterized by Th1/Th2 imbalance in which Th2 type cells and cytokines often increase. However, few studies have investigated whether it can reduce or prevent the symptoms and attacks in children with asthma. This study evaluated the effect of inactivated Mycobacterium phlei inhaled by an atomizing device placed on asthmatic children. In this randomized, single-center, Seretide-controlled study, children aged 4-12 years with newly diagnosed, moderate, persistent asthma were treated with either inhaled inactivated M. phlei or inhaled Seretide patch. The efficacy of inhaled inactivated M. phlei was related with the alleviation of asthma symptoms, improvement of lung function and reduction of bronchial hyper-responsiveness and total serum IgE, which was similar with Seretide. These findings may have important clinical value in confirming inhaled inactivated M. phlei as a new therapeutic method in moderately asthmatic children.

Gut matters: microbe-host interactions in allergic diseases

The human body can be considered a metaorganism made up of its own eukaryotic cells and trillions of microbes that colonize superficial body sites, such as the skin, airways, and gastrointestinal tract. The coevolution of host and microbes brought about a variety of molecular mechanisms, which ensure a peaceful relationship. The mammalian barrier and immune functions warrant simultaneous protection of the host against deleterious infections, as well as tolerance toward harmless commensals. Because these pivotal host functions evolved under high microbial pressure, they obviously depend on a complex network of microbe-host interactions. The rapid spread of immune-mediated disorders, such as autoimmune diseases, inflammatory bowel diseases, and allergies, in westernized countries is thus thought to be due to environmentally mediated disturbances of this microbe-host interaction network. The aim of the present review is to highlight the importance of the intestinal microbiota in shaping host immune mechanisms, with particular emphasis on allergic diseases and possible intervention strategies.