Oral administration of chitin and chitosan prevents peanut-induced anaphylaxis in a murine food allergy model

Development and evaluation of mouse anti-Ara h 1 and Ara h 3 IgE monoclonal antibodies for advancing peanut allergy research

Immediate hypersensitivity reactions to peanuts are a considerable public health concern due to the acute and severe IgE mediated reactions. To conduct research on the pathogenesis and therapeutics of peanut allergies, it is imperative to have mouse anti-crude peanut extract (CPE) IgE monoclonal antibodies (mAbs) for both in-vitro and in-vivo assays. Without these tools, it is difficult to advance research in this field. In this study, four hybridomas producing anti-CPE IgE mAbs were developed and the IgE mAbs were validated using immune-blot analysis, Sandwich ELISA, Indirect ELISA, a cell-based assay using RBL-2H3 cells, and footpad type I hypersensitivity reaction studies in mice. The results indicate that two of the four mAbs can be effectively used for both in-vitro and in-vivo peanut allergy studies, as they induce allergic reactions with sensitization alone in mice. These novel anti-Ara h1 and Ara h 3 IgE mAbs, in combination with the detailed protocols outlined in this article, offer valuable guidance for studying acute allergic reactions involving mast cells across various platforms. With some considerations, the IgE mAbs can significantly advance peanut allergy research.

Chitinases and chitinase-like proteins in asthma

Despite the lack of endogenous chitin synthesis, mammalian genomes encode two enzymatically active true chitinases (chitotriosidase and acidic mammalian chitinase) and a variable number of chitinase-like proteins (CLPs) that have no enzyme activity but bind chitin. Chitinases and CLPs are prominent components of type-2 immune response-mediated respiratory diseases. However, despite extensive research into their role in allergic airway disease, there is still no agreement on whether they are mere biomarkers of disease or actual disease drivers. Functions ascribed to chitinases and CLPs include, but are not limited to host defense against chitin-containing pathogens, directly promoting inflammation, and modulating tissue remodeling and fibrosis. Here, we discuss in detail the chitin-dependent and -independent roles of chitinases and CLPs in the context of allergic airway disease, and recent advances and emerging concepts in the field that might identify opportunities for new therapies.

A Comprehensive Review on Natural Bioactive Compounds and Probiotics as Potential Therapeutics in Food Allergy Treatment

Food allergy is rising at an alarming rate and is a major public health concern. Globally, food allergy affects over 500 million people, often starting in early childhood and increasingly reported in adults. Commercially, only one approved oral immunotherapy-based treatment is currently available and other allergen-based immunotherapeutic are being investigated in clinical studies. As an alternative approach, a substantial amount of research has been conducted on natural compounds and probiotics, focusing on the immune modes of action, and therapeutic uses of such sources to tackle various immune-related diseases. Food allergy is primarily mediated by IgE antibodies and the suppression of allergic symptoms seems to be mostly modulated through a reduction of allergen-specific IgE antibodies, upregulation of blocking IgG, and downregulation of effector cell activation (e.g., mast cells) or expression of T-helper 2 (Th-2) cytokines. A wide variety of investigations conducted in small animal models or cell-based systems have reported on the efficacy of natural bioactive compounds and probiotics as potential anti-allergic therapeutics. However, very few lead compounds, unlike anti-cancer and anti-microbial applications, have been selected for clinical trials in the treatment of food allergies. Natural products or probiotic-based approaches appear to reduce the symptoms and/or target specific pathways independent of the implicated food allergen. This broad range therapeutic approach essentially provides a major advantage as several different types of food allergens can be targeted with one approach and potentially associated with a lower cost of development. This review provides a brief overview of the immune mechanisms underlying food allergy and allergen-specific immunotherapy, followed by a comprehensive collection of current studies conducted to investigate the therapeutic applications of natural compounds and probiotics, including discussions of their mode of action and immunological aspects of their disease-modifying capabilities.

Structural analysis and allergenicity assessment of an enzymatically cross-linked bovine α-lactalbumin polymer

Enzymatic cross-linking is frequently used in bio-processing of dairy products since it could change the physiochemical and functional characterization.

Chitosan Oligosaccharide Exerts Anti-Allergic Effect against Shrimp Tropomyosin-Induced Food Allergy by Affecting Th1 and Th2 Cytokines

BACKGROUND

Shrimp-derived allergen has a serious impact on people's health. Chitosan oligosaccharide (COS) has anti-allergic action but its function on shrimp allergen-induced allergy and related molecular mechanisms remain unclear.

METHODS

COS and its degrees of polymerization (DP) were selected to interact with shrimp tropomyosin (TM) and IgE was measured. A mouse model of food allergy was established by receiving shrimp TM intraperitoneally. The models were treated with different concentrations of COS. Fecal and serum histamine, serum IgE, IgG1 and IgG2a, and inflammatory cytokines were measured.

RESULTS

The main products for COS were DP2-6 with the contents of 6, 40, 26, 16, and 4%, respectively, and reacted with shrimp TM increasingly when COS DP was increased. Severe symptoms of food allergy were observed in the TM group (diarrhea, anaphylactic response, and rectal temperature). In contrast, COS treatment improved these symptoms significantly (p < 0.05). The sensitized mice were desensitized after they were treated with 1 mg/kg COS. COS treatment significantly reduced serum IgE and IgG1 levels, and increased IgG2a levels (p < 0.05). COS consumption decreased fecal and serum histamine. COS treatment reduced Th2 cytokine (IL-4, IL-5, and IL-13) levels and increased the Th1 cytokine (IFN-γ) level (p < 0.05).

CONCLUSIONS

COS showed anti-allergy properties by regulating the levels of Th1 and Th2 cytokines.

Chitin and Its Effects on Inflammatory and Immune Responses

Chitin, a potential allergy-promoting pathogen-associated molecular pattern (PAMP), is a linear polymer composed of N-acetylglucosamine residues which are linked by β-(1,4)-glycosidic bonds. Mammalians are potential hosts for chitin-containing protozoa, fungi, arthropods, and nematodes; however, mammalians themselves do not synthetize chitin and thus it is considered as a potential target for recognition by mammalian immune system. Chitin is sensed primarily in the lungs or gut where it activates a variety of innate (eosinophils, macrophages) and adaptive immune cells (IL-4/IL-13 expressing T helper type-2 lymphocytes). Chitin induces cytokine production, leukocyte recruitment, and alternative macrophage activation. Intranasal or intraperitoneal administration of chitin (varying in size, degree of acetylation and purity) to mice has been applied as a routine approach to investigate chitin's priming effects on innate and adaptive immunity. Structural chitin present in microorganisms is actively degraded by host true chitinases, including acidic mammalian chitinases and chitotriosidase into smaller fragments that can be sensed by mammalian receptors such as FIBCD1, NKR-P1, and RegIIIc. Immune recognition of chitin also involves pattern recognition receptors, mainly via TLR-2 and Dectin-1, to activate immune cells to induce cytokine production and creation of an immune network that results in inflammatory and allergic responses. In this review, we will focus on various immunological aspects of the interaction between chitin and host immune system such as sensing, interactions with immune cells, chitinases as chitin degrading enzymes, and immunologic applications of chitin.

In vivo anti-psoriatic activity, biodistribution, sub-acute and sub-chronic toxicity studies of orally administered methotrexate loaded chitin nanogel in comparison with methotrexate tablet

The anti-psoriatic efficacy of orally administered methotrexate loaded chitin nanogel (MCNG) was evaluated (two doses- 2.715 mg/kg and 5.143 mg/kg) and compared against orally administered methotrexate tablet MTX (5.143 mg/kg). MCNG at both dose levels of 2.715 mg/kg and 5.143 mg/kg exhibited significant anti-psoriatic activity which is very much comparable with MTX, caused normalization of histological features and inflammatory score associated with induced psoriasis. Biodistribution studies revealed the presence of drug in serum and in vital organs at all the three cases with highest amount in MCNG at 5.143 mg/kg dose, followed by MTX tablet and are lowest in MCNG at 2.715 mg/kg dose. MCNG at the highest dose of 5.143 mg/kg caused liver, lung and kidney toxicities on sub acute toxicity studies and MTX tablet was found to be toxic on liver and lung on sub chronic toxicity studies. MCNG 2.715 mg/kg was found to be safe on both sub acute and sub chronic administrations, suggesting that it can provide sufficient serum and tissue level of methotrexate necessary to clear psoriatic lesions, without inducing systemic toxicity and expected to be a better alternative for orally administered conventional methotrexate tablet for patients who need systemic medications for psoriasis.

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.

Food allergy: immune mechanisms, diagnosis and immunotherapy

Food allergy is a pathological, potentially deadly, immune reaction triggered by normally innocuous food protein antigens. The prevalence of food allergies is rising and the standard of care is not optimal, consisting of food-allergen avoidance and treatment of allergen-induced systemic reactions with adrenaline. Thus, accurate diagnosis, prevention and treatment are pressing needs, research into which has been catalysed by technological advances that are enabling a mechanistic understanding of food allergy at the cellular and molecular levels. We discuss the diagnosis and treatment of IgE-mediated food allergy in the context of the immune mechanisms associated with healthy tolerance to common foods, the inflammatory response underlying most food allergies, and immunotherapy-induced desensitization. We highlight promising research advances, therapeutic innovations and the challenges that remain.

Induction of colitis in mice with food allergen-specific immune response

The pathogenesis of intestinal chronic inflammation is unclear. Food allergy plays an important role in the induction of intestinal inflammation. This study aims to test a hypothesis that food allergy initiates colitis. In this study, BALB/c mice were sensitized to a common food allergen, ovalbumin (OVA) with cholera toxin (CT) as an adjuvant. The colon epithelial barrier function was assessed with Ussing chamber technique. Expression of T cell immunoglobulin mucin domain molecule-4 (TIM4) in dendritic cells was evaluated by flow cytometry, RT-PCR and Western blotting. The results showed that allergen-related colitis was induced in mice as shown by heavy infiltration of inflammatory cells in the colon mucosa, loss of body weight of mice, increases in myeloperoxidase, tumor necrosis factor-α, interleukin-4, OVA-specific IgE in the colon tissue. The colon epithelial barrier function was markedly compromised in colitis group mice, which was mimicked by exposure the colon mucosa to CT in Ussing chamber. High frequency of TIM4⁺ dendritic cells was detected in the colon mucosa of colitis mice. Exposure of dendritic cells to CT markedly increased the expression of TIM4. We conclude that IBD-like inflammation can be induced in the mouse colon by the food allergen-related immune response.

Crosslinking of peanut allergen Ara h 2 by polyphenol oxidase: digestibility and potential allergenicity assessment

BACKGROUND

Peanut is one of the eight major food allergens. Its allergen, Ara h 2, can be recognized by over 90% of serum IgE samples from peanut-allergic patients. Therefore, reducing the allergenicity of Ara h 2 is especially important.

RESULTS

In the present study, polyphenol oxidase (PPO), a protein cross-linking reaction catalyst that acts on tyrosine residue, was used to modify Ara h 2. After crosslinking, the microstructure, digestibility, IgG binding capability and IgE binding capability of Ara h 2 were analyzed. Cross-linking decreased the potential allergenicity of Ara h 2 by masking the allergen epitope, while the antigenicity of Ara h 2 changed slightly. After crosslinking, the apparent diameter of Ara h 2 was altered from 300 to 1700 nm or 220 nm, indicating that polymerization could either be inter- or intramolecular. Regarding digestibility, crosslinked Ara h 2 was relatively more easily digested by gastric fluid compared with the untreated Ara h 2, but much more difficult in the intestinal fluid.

CONCLUSION

The crosslinking reaction catalyzed by PPO, as a non-thermal process, may be beneficial for avoiding food allergy. The reaction could mask allergen epitopes, decreasing the allergenicity of Ara h 2. © 2015 Society of Chemical Industry.

Chitin nanofibrils suppress skin inflammation in atopic dermatitis-like skin lesions in NC/Nga mice

We evaluated the effect of chitin nanofibril (CNF) application via skin swabs on an experimental atopic dermatitis (AD) model. AD scores were lower, and hypertrophy and hyperkeratosis of the epidermis were suppressed after CNF treatment. Furthermore, inflammatory cell infiltration in both the epidermis and dermis was inhibited. CNFs also attenuated histological scores. The suppressive effects of CNFs were equal to those of corticosteroid application; however, chitin did not show these effects. CNF application might have anti-infllammatory effects via suppression of the activation of nuclear factor-kappa B, cyclooxygenase-2, and inducible nitric oxide synthase. In an early-stage model of experimental AD, CNFs suppressed AD progression to the same extent as corticosteroids. They also suppressed skin inflammation and IgE serum levels. Our findings indicate that CNF application could aid in the prevention or treatment of AD skin lesions.

The future of biologics: applications for food allergy

Allergic diseases affect millions worldwide, with growing evidence of an increase in allergy occurrence over the past few decades. Current treatments for allergy include corticosteroids to reduce inflammation and allergen immunotherapy; however, some subjects experience treatment-resistant inflammation or adverse reactions to these treatments, and there are currently no approved therapeutics for the treatment of food allergy. There is a dire need for new therapeutic approaches for patients with poorly controlled atopic diseases and a need to improve the safety and effectiveness of allergen immunotherapy. Improved understanding of allergy through animal models and clinical trials has unveiled potential targets for new therapies, leading to the development of several biologics to treat allergic diseases. This review focuses on the mechanisms that contribute to allergy, with an emphasis on future targets for biologics for the treatment of food allergy. These biologics include immunotherapy with novel anti-IgE antibodies and analogs, small-molecule inhibitors of cell signaling, anti-type 2 cytokine mAbs, and TH1-promoting adjuvants.

Extracellular overexpression of chitosanase from Bacillus sp. TS in Escherichia coli

The chitosanase gene from a Bacillus sp. strain isolated from soil in East China was cloned and expressed in Escherichia coli. The gene had 1224 nucleotides and encoded a mature protein of 407 amino acid residues. The optimum pH and temperature of the purified recombinant chitosanase were 5.0 and 60 °C, respectively, and the enzyme was stable below 40 °C. The K m, V max, and specific activity of the enzyme were 1.19 mg mL(-1), 674.71 μmol min(-1) at 50 °C, and 555.3 U mg(-1), respectively. Mn(2+) was an activator of the recombinant chitosanase, while Co(2+) was an inhibitor. Hg(2+) and Cu(2+) inhibited the enzyme at 1 mM. The highest level of enzyme activity (186 U mL(-1)) was achieved in culture medium using high cell-density cultivation in a 7-L fermenter. The main products of chitosan hydrolyzed by recombinant chitosanase were (GlcN)3-6. The chitosanases was successfully secreted to the culture media through the widely used SecB-dependent type II pathway in E. coli. The high yield of the extracellular overexpression, relevant thermostability, and effective hydrolysis of commercial grade chitosan showed that this recombinant enzyme had a great potential for industrial applications.

Anticancer properties of chitosan on human melanoma are cell line dependent

PURPOSE

Chitosan, a natural macromolecule, is widely used in medical and pharmaceutical fields because of its distinctive properties such as bactericide, fungicide and above all its antitumor effects. Although its antitumor activity against different types of cancer had been previously described, its mechanism of action was not fully understood.

MATERIALS AND METHODS

Coating of chitosan has been used in cell cultures with A375, SKMEL28, and RPMI7951 cell lines. Adherence, proliferation and apoptosis were investigated.

RESULTS

Our results revealed that whereas chitosan decreased adhesion of primary melanoma A375 cell line and decreased proliferation of primary melanoma SKMEL28 cell line, it had potent pro-apoptotic effects against RPMI7951, a metastatic melanoma cell line. In these latter cells, inhibition of specific caspases confirmed that apoptosis was effected through the mitochondrial pathway and Western blot analyses showed that chitosan induced an up regulation of pro-apoptotic molecules such as Bax and a down regulation of anti-apoptotic proteins like Bcl-2 and Bcl-XL. More interestingly, chitosan exposure induced an exposition of a greater number of CD95 receptor at RPMI7951 surface, making them more susceptible to FasL-induced apoptosis.

CONCLUSION

Our results indicate that chitosan could be a promising agent for further evaluations in antitumor treatments targeting melanoma.

Preventive effects of skullcap (Scutellaria baicalensis) extract in a mouse model of food allergy

ETHNOPHARMACOLOGICAL RELEVANCE

Food allergy, which accompanies acute symptoms such as pruritus, vomiting, diarrhea, and lethal anaphylactic shock is an increasing clinical problem. Skullcap (Scutellaria baicalensis Georgi) has been widely used as a traditional herbal medicine to treat inflammation, cancer, and allergy, but its effects in treating food allergy are not yet known.

MATERIALS AND METHODS

To examine the effect of skullcap on food allergy, female BALB/c mice were sensitized with 20 μg OVA and 2mg alum by intraperitoneal injection on day 0. From day 17, mice were orally challenged with OVA (50 mg) in saline every 3 days, for a total of six times. To investigate the preventive effect, skullcap (25 mg/kg) was orally administered every day from day 17 to 34.

RESULTS

Food allergy symptoms were evaluated by the criteria for diarrhea, anaphylactic response, and rectal temperature. Severe symptoms of food allergy were observed in the sham group (diarrhea, 3 points; anaphylactic response, 2.6 points; rectal temperature, -8.36 °C. In contrast, the skullcap treatment group had a significantly suppressed OVA-induced anaphylactic response (1.3 points) and rectal temperature (-4.76°C). Moreover, both OVA-specific IgE, Th17 cytokine (IL-17), and Th2-related cytokines (IL-4, IL-5, IL-10, and IL-13), which increased with food allergy, were significantly inhibited by skullcap treatment.

CONCLUSION

We demonstrate that the administration of skullcap attenuates OVA-induced food allergy symptoms through regulating systemic immune responses of Th cells. These results indicate that skullcap may be a potential candidate as a preventive agent for food allergy.

Emerging therapies for food allergy

Food allergy is a common condition for which there are currently no approved treatments except avoidance of the allergenic food and treatment of accidental reactions. There are several potential treatments that are under active investigation in animal and human studies, but it is not yet clear what the best approach may be. Here, we review approaches that are currently in clinical trials, including oral, sublingual, and epicutaneous immunotherapy, immunotherapy combined with anti-IgE, and Chinese herbal medicine as well as approaches that are in preclinical or early clinical investigation, including modified protein immunotherapy, adjuvants, DNA vaccines, and helminth administration. We discuss the importance of fully exploring the risks and benefits of any treatment before it is taken to general clinical practice and the need for clarity about the goals of treatment.

Chitooligosaccharide and its derivatives: preparation and biological applications

Chitin is a natural polysaccharide of major importance. This biopolymer is synthesized by an enormous number of living organisms; considering the amount of chitin produced annually in the world, it is the most abundant polymer after cellulose. The most important derivative of chitin is chitosan, obtained by partial deacetylation of chitin under alkaline conditions or by enzymatic hydrolysis. Chitin and chitosan are known to have important functional activities but poor solubility makes them difficult to use in food and biomedicinal applications. Chitooligosaccharides (COS) are the degraded products of chitosan or chitin prepared by enzymatic or chemical hydrolysis of chitosan. The greater solubility and low viscosity of COS have attracted the interest of many researchers to utilize COS and their derivatives for various biomedical applications. In light of the recent interest in the biomedical applications of chitin, chitosan, and their derivatives, this review focuses on the preparation and biological activities of chitin, chitosan, COS, and their derivatives.