Serine proteases, their inhibitors and allergy

Combination of Gut Microbial Features and the Proteomic Pattern Revealed Changes in Specific Intestinal Luminal Factors and Mechanisms of Their Regulation of Gluten Allergy

Recent research consensus has highlighted the role of intestinal luminal factors in the association between intestinal microenvironment homeostasis and food allergy. However, the association between intestinal immune homeostasis and food allergy-related proteomic features remains elusive. In this study, we aimed to investigate the changes in gluten allergy (GA)-defined phenotypes and endotypes and intestinal microenvironment factors in BALB/c mice and linked GA to colonic proteomic signatures. Combined with increased allergy and diarrhea scores, intense antibody responses and abnormalities in T-cell cytokine production were induced in mice. GA-associated disruption of intestinal microenvironment homeostasis was underlined by the increased colonic pH, decreased intestinal antioxidant capacity, impaired intestinal barrier function, and decreased production and imbalanced proportions of short-chain fatty acids. 16S rRNA amplicon sequencing showed that the gut microbiota dysbiosis in mice was characterized by significant enrichment of six bacterial taxonomic units, including Prevotellaceae, Escherichia Shigella, Alloprevotella, Escherichia coli, Bacteroides vulgatus, and Lachnospiraceae bacterium DW59, which was correlated with immune end points. Using a label-free proteomics quantitative approach, 24 differentially expressed proteins linking GA-induced gut dysbiosis were identified, with four of them enriched in the serine endopeptidase inhibitor activity pathway. The development of GA in mice was associated with changes in specific intestinal luminal factors and may be mediated by serine protease activity-associated metabolic routes.

Current Understanding of the Role of Eosinophils in CRSwNP and Implications for Treatment with Mepolizumab and Benralizumab

BACKGROUND

International consensus statements now subdivide chronic rhinosinusitis (CRS) into several phenotypes and endotypes, including the presence of polyps (CRSwNP) and eosinophilia (eCRSwNP). Biological treatments aimed at blocking eosinophilic inflammation in CRSwNP via interleukin 5 (IL5) or the interleukin 5 receptor (IL5R) have demonstrated limited efficacy thus far.

OBJECTIVE

To review the pathophysiology of eCRSwNP, the evidence for mepolizumab (anti-IL5) and benralizumab (anti-IL5R) in CRSwNP, and to highlight areas for future research and therapeutic intervention.

METHODS

Primary and secondary literature search.

RESULTS

Clinical trials on mepolizumab and benralizumab in CRSwNP are limited and restricted by trial design which prevents direct comparison with other interventions, including surgery. Both agents would appear to provide some benefit in reducing nasal polyp size but limited clinical patient benefit. Molecular biological research highlights that eCRSwNP can occur in the absence of IL5 and that other cells/cytokines play an important part in the disease's pathophysiology.

CONCLUSION

Blockade of IL5/IL5R alone would appear to provide limited "real life" clinical benefit in patients with CRSwNP due to the complexities of the pathophysiology of the condition. Therapy aimed at several simultaneous cytokine targets has logic but well-designed trials are unlikely to be forthcoming in the short term due to the financial cost and commercial conflicts of interest.

Allergen Content and Protease Activity in Milk Feeds from Mothers of Preterm Infants

Rationale: There is little information regarding the allergen content of milk feeds in the preterm population. Previous studies have not performed a broad analysis of the allergenic peptide content and protease activity of milk feeds in this population. Methods: To evaluate feasibility, we initially performed mass spectrometry on 4 human milk (HM) samples (2 term and 2 preterm) from the Mommy's Milk Human Milk Biorepository (HMB) and analyzed the results against the University of Nebraska FASTA database and UniProt for a total of 2,211 protein sequences. We then further analyzed five samples from the Microbiome, Atopy, and Prematurity (MAP) study including peptidomic and protease activity analysis. Results: Each HMB sample had between 806 and 1,007 proteins, with 37-44 nonhuman proteins/sample encompassing 26 plant and animal species. In the preterm MAP samples, 784 digested nonhuman proteins were identified, 30 were nonbovine in origin. Proteins from 23 different species including aeroallergens, food, and contact allergens were identified. Protease activity was highest in HM samples without human milk fortifier and lowest in preterm formula. Conclusions: These findings represent the first preterm milk feed mass spectrometry and protease analysis with identification of known allergenic proteins to food, contact, and aeroallergens. These results raise questions of whether the composition of milk feeds in the neonatal intensive care unit impact the development of atopic disease in the preterm population and whether the complex interaction between allergens, proteases, and other HM components can serve to induce sensitization or tolerance to allergens in infants. Clinical Trial Registration Number: NCT04835935.

Tandem mass tags labeled quantitative proteomics to study the effect of tobacco smoke exposure on the rat lung

BACKGROUND

The causal link between tobacco smoke exposure (TSE) and numerous severe respiratory system diseases (RSD), including chronic bronchitis, chronic obstructive pulmonary disease, and lung cancer, is well established. However, the pathogenesis of TSE-induced RSD remains incompletely understood. This research aims to detect the pathogenetic mechanisms and potential therapeutic targets of TSE-induced RSD.

METHODS

This study employed TSE model which rats were exposed to a concentration of 60% tobacco smoke in a toxicant exposure system for four weeks. Tandem mass tags (TMT) labeled quantitative proteomics combined with off-line high pH reversed-phase fractionation, and nano-liquid chromatography-mass spectrometry method (off-line high pH RPF-nano-LC-MS/MS) were adopted to detect differentially expressed proteins (DEPs) in the lung tissues of the TSE model rats and to compare them with those in control. The accuracy of the results was verified by western blot.

RESULTS

Compared with the control group, 33 proteins in the TSE model group's lung tissues showed significant differential expression. Analysis based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways indicated that, several biological pathways, such as the steroid biosynthesis pathway, were involved and played significant roles in the pathogenesis of the experimental group's TSE.

CONCLUSIONS

These findings make a crucial contribution to the search for a comprehensive understanding of TSE-induced RSD's pathogenesis, and furthermore provide guidance for the diagnosis and treatment of TSE-induced RSD.

Quail egg homogenate alleviates food allergy induced eosinophilic esophagitis like disease through modulating PAR-2 transduction pathway in peanut sensitized mice

The present pharmacotherapy for eosinophilic esophagitis (EoE) fundamentally depend on inhaled corticosteroids. Despite the fact that oral intake of topical steroids can be successful in restricting EoE-related inflammation, there are concerns with respect to the long term utilization of steroids, especially in kids. In the current research, we assess the effect of quail egg, which is reportedly a known serine protease inhibitor, on symptomatology and immune responses in a peanut-sensitized mouse model of food allergy induced EoE. Daily oral treatment with quail egg attenuated mice symptomatology and immune response. Treatment with quail egg inhibited antigen-prompted increments in mouse tryptase and eosinophil cationic protein (ECP) in serum and eosinophil in inflamed tissues like oesophagus, lung, and digestive system. Quail egg treatment resulted in decreased antibody specific IgE and IgG1 and a variety of inflammatory genes that were abnormally expressed in EoE. Other effects included increased IL-10, decreased PAR-2 activation and NF-kB p65 in inflamed tissues. Our results suggest that quail egg treatment may have therapeutic potential in attenuating the symptoms of food allergy induced EoE like disease through regulating PAR-2 downstream pathway by blocking the activation of the transcription factor NF-kB p65 activity.

Serine Protease Zymography: Low-Cost, Rapid, and Highly Sensitive RAMA Casein Zymography

To detect serine protease activity by zymography, casein and CBB stain have been used as a substrate and a detection procedure, respectively. Casein zymography has been using substrate concentration at 1 mg/mL and employing conventional CBB stain. Although ordinary casein zymography provides reproducible results, it has several disadvantages including time-consuming and relative low sensitivity. Improved casein zymography, RAMA casein zymography, is rapid and highly sensitive. RAMA casein zymography completes the detection process within 1 h after incubation and increases the sensitivity at least by tenfold. In addition to serine protease, the method also detects metalloprotease 7 (MMP7, Matrilysin) with high sensitivity.

Developing a framework for assessing chemical respiratory sensitization: A workshop report

Respiratory tract sensitization can have significant acute and chronic health implications. While induction of respiratory sensitization is widely recognized for some chemicals, validated standard methods or frameworks for identifying and characterizing the hazard are not available. A workshop on assessment of respiratory sensitization was held to discuss the current state of science for identification and characterization of respiratory sensitizer hazard, identify information facilitating development of validated standard methods and frameworks, and consider the regulatory and practical risk management needs. Participants agreed on a predominant Th2 immunological mechanism and several steps in respiratory sensitization. Some overlapping cellular events in respiratory and skin sensitization are well understood, but full mechanism(s) remain unavailable. Progress on non-animal approaches to skin sensitization testing, ranging from in vitro systems, -omics, in silico profiling, and structural profiling were acknowledged. Addressing both induction and elicitation phases remains challenging. Participants identified lack of a unifying dose metric as increasing the difficulty of interpreting dosimetry across exposures. A number of research needs were identified, including an agreed list of respiratory sensitizers and other asthmagens, distinguishing between adverse effects from immune-mediated versus non-immunological mechanisms. A number of themes emerged from the discussion regarding future testing strategies, particularly the need for a tiered framework respiratory sensitizer assessment. These workshop present a basis for moving towards a weight-of-evidence assessment.

Difference in the breast milk proteome between allergic and non-allergic mothers

BACKGROUND

Breastfeeding has been linked to a reduction in the prevalence of allergy and asthma. However, studies on this relationship vary in outcome, which may partly be related to differences in breast milk composition. In particular breast milk composition may differ between allergic and non-allergic mothers. Important components that may be involved are breast milk proteins, as these are known to regulate immune development in the newborn. The objective of this study was therefore to explore differences in the proteins of breast milk from 20 allergic and non-allergic mothers. The results from this comparison may then be used to generate hypotheses on proteins associated with allergy in their offspring.

METHODS

Milk samples from allergic and non-allergic mothers were obtained from the PIAMA project, a prospective birth cohort study on incidence, risk factors, and prevention of asthma and inhalant allergy. Non-targeted proteomics technology, based on liquid chromatography and mass spectrometry, was used to compare breast milk from allergic and non-allergic mothers.

RESULTS

Nineteen proteins, out of a total of 364 proteins identified in both groups, differed significantly in concentration between the breast milk of allergic and non-allergic mothers. Protease inhibitors and apolipoproteins were present in much higher concentrations in breast milk of allergic than non-allergic mothers. These proteins have been suggested to be linked to allergy and asthma.

CONCLUSIONS

The non-targeted milk proteomic analysis employed has provided new targets for future studies on the relation between breast milk composition and allergy.

The Serine Protease Inhibitor, 4-(2-aminoethyl) Benzene Sulfonyl Fluoride Hydrochloride, Reduces Allergic Inflammation in a House Dust Mite Allergic Rhinitis Mouse Model

Purpose

Serine protease inhibitors are involved in immune development, anti-inflammatory mechanisms, and tissue repair. In the present study, the serine protease inhibitor 4-(2-aminoethyl) benzene sulfonyl fluoride hydrochloride (AEBSF) was evaluated for its prophylactic and therapeutic applications in a mouse model of allergic rhinitis (AR).

Methods

BALB/c mice were divided into 5 groups: contol (CON), Dermatophagoides farinae (Derf), AR mice treated with AEBSF before sensitization (S), AR mice treated with AEBSF after challenge (C), and steroid groups. Derf was used as an allergen. AEBSF was administered before S or after C. Allergic symptom scores, eosinophil counts, proteolytic activity, interferon-γ, interleukin (IL)-10 levels and serum Derf-specific IgE levels were measured. T-bet, GATA-3, Foxp3, IL-13, and transforming growth factor (TGF)-β mRNA levels were determined using real-time polymerase chain reaction. CD4⁺CD25⁺Foxp3⁺ T cells were assessed using flow cytometry.

Results

Symptom scores, serum Derf-specific IgE levels, GATA-3 mRNA levels, IL-13 mRNA levels, and tissue eosinophil counts decreased in both the S and C groups (P<0.05). Additionally, the percentage of CD4⁺CD25⁺Foxp3⁺ T cells, IL-10 levels, and Foxp3 mRNA levels increased in the S and C groups compared with those in the Derf group (P<0.05). AEBSF treatment decreased the proteolytic activity in the S and C groups (P<0.05).

Conclusions

Prophylactic and therapeutic treatment with AEBSF significantly reduces allergic airway inflammation and can induce regulatory T cells in a murine model of AR.

House dust mite allergy in Korea: the most important inhalant allergen in current and future

The house-dust mite (HDM), commonly found in human dwellings, is an important source of inhalant and contact allergens. In this report, the importance of HDM allergy in Korea and the characteristics of allergens from dust mite are reviewed with an emphasis on investigations performed in Korea. In Korea, Dermatophagoides farinae is the dominant species of HDM, followed by D. pteronyssinus. Tyrophagus putrescentiae is also found in Korea, but its role in respiratory allergic disease in Korea is controversial. The relatively low densities of mite populations and concentrations of mite major allergens in dust samples from Korean homes, compared to westernized countries, are thought to reflect not only different climatic conditions, but also cultural differences, such as the use of 'ondol' under-floor heating systems in Korean houses. HDM are found in more than 90% of Korean houses, and the level of exposure to HDM is clinically significant. About 40%-60% of Korean patients suffering from respiratory allergies, and more than 40% of patients suffering from atopic dermatitis, are sensitized to HDM. Mite allergens can be summarized according to their inherent auto-adjuvant activities and/or their binding affinities to the adjuvant-like substances: proteolytic enzymes, lipid binding proteins, chitin binding proteins, and allergens not associated with adjuvant-like activity. In general, allergens with a strong adjuvant-like activity or adjuvant-binding activity elicit potent IgE reactivity. In Korea, Der f 2 is the most potent allergen, followed by Der f 1. Immune responses are modulated by the properties of the allergen itself and by the adjuvant-like substances that are concomitantly administered with the antigens. Characterization of allergenic molecules and elucidation of mechanisms by which adjuvant-like molecules modulate allergic reactions, not only in Korea but also worldwide, will provide valuable information on allergic diseases, and are necessary for the development of diagnostic tools and therapeutic strategies.

A contaminant trypsin-like activity from the timothy grass pollen is responsible for the conflicting enzymatic behavior of the major allergen Phl p 1

We intend to solve whether or not Phl p 1 can be regarded as a protease. A group reported that Phl p 1 has papain-like properties and later on, that this allergen resembles cathepsin B, while another one demonstrated that Phl p 1 lacks proteinase activity and suggested that the measured activity may rise either from a recombinant Phl p 1 contaminant or as a result of an incompletely purified natural allergen. A third group reported Phl p 1 to act by a non-proteolytic activity mechanism. We report the purification of the natural Phl p 1 by means of hydrophobic interaction, gel filtration and STI-Sepharose affinity chromatographies. The Phl p 1 purity was assessed by silver-stained SDS-PAGE and by 'in-gel' and 'gel-free' approaches associated to mass spectrometry analyses. The proteolytic activity was measured using Boc-Gln-Ala-Arg-AMC and Z-Phe-Arg-AMC as substrates. While amidolytic activity could be measured with Phl p 1 after rechromatography on gel filtration, it however completely disappeared after chromatography on STI-Sepharose. The contaminant activity co-eluting with Phl p 1 was not affected by cysteine proteases inhibitors and other thiol-blocking agents, by metalloproteases inhibitors and by aspartic proteases inhibitors. However, it was completely inhibited by low molecular weight and proteinaceous serine proteases inhibitors. TLCK, but not TPCK, inhibited the contaminant activity, showing a trypsin-like behavior. The pH and temperature optimum were 8.0 and 37°C, respectively. These data indicated that Phl p 1 is not a protease. The contaminant trypsin-like activity should be considered when Phl p 1 allergenicity is emphasized.

The protease allergen Pen c 13 induces allergic airway inflammation and changes in epithelial barrier integrity and function in a murine model

Fungal allergens are associated with the development of asthma, and some have been characterized as proteases. Here, we established an animal model of allergic airway inflammation in response to continuous exposure to proteolytically active Pen c 13, a major allergen secreted by Penicillium citrinum. In functional analyses, Pen c 13 exposure led to increased airway hyperresponsiveness, significant inflammatory cell infiltration, mucus overproduction, and collagen deposition in the lung, dramatically elevated serum levels of total IgE and Pen c 13-specific IgE and IgG1, and increased production of the Th2 cytokines IL-4, IL-5, and IL-13 by splenocytes stimulated in vitro with Pen c 13. To examine the mechanisms involved in the regulation of allergenicity by Pen c 13, we performed two-dimensional fluorescence difference gel electrophoresis analysis combined with nano-LC-MS/MS, followed by bioinformatics analysis to identify potential targets that associated with allergic inflammation, which suggested that galectin-3 and laminin might be involved in novel pathogenic mechanisms. Finally, we focused on junctional proteins between cells, because, in addition to opening of the epithelial barrier by environmental proteases possibly being the initial step in the development of asthma, these proteins are also associated with actin rearrangement. Taken together, our findings indicate that Pen c 13 exposure causes junctional structure alterations and actin cytoskeletal rearrangements, resulting in increased permeability and airway structural changes. These effects probably change the lung microenvironment and foster the development of allergic sensitization.

Optimization of allergen standardization

Preparation of high quality allergen extracts is essential for the diagnosis and immunotherapy of allergic disorders. Standardization of allergen extracts concerns determination of the allergen unit, development of reference material and measurement of the overall IgE binding capacity of an allergen extract. Recently, quantification of individual allergens has been the main focus of allergen standardization because the allergenicity of most allergen extracts is known to be mainly dependent on the content of a small number of allergen molecules. Therefore, characterization of major allergens will facilitate the standardization of allergens. In this article, we review the current state of allergen standardization. In addition, we briefly summarize the components of allergen extracts that should be under control for the optimization of allergen standardization, since its adjuvant-like activities could play an important role in allergic reactions even though the molecule itself does not bind to the IgE antibodies from subjects.

Specific profiles of house dust mite sensitization in children with asthma and in children with eczema

Sensitization to house dust mites (HDM) is highly prevalent among the young atopic population in Singapore. Previously published data suggest that individuals with skin allergies show preferred sensitization to Dermatophagoides pteronyssinus while individuals with pure respiratory allergies show preferred sensitization to Blomia tropicalis. The aim of our study was to compare the sensitization profiles between children with asthma and those with eczema to D. pteronyssinus and B. tropicalis and their specific allergens. A total of 60 children, 30 with asthma and 30 with eczema were recruited. IgE levels specific for a panel of HDM allergens from the two mite species were measured using enzyme-linked immunosorbent assay. The asthma group showed highest sensitization to Blo t5 while the eczema group showed highest sensitization to Der p5. Comparison between the two disease groups showed that the eczema group had significantly higher IgE levels for Der p (p = 0.042) and its allergens Der p1 (p = 0.019) and Der p5 (p = 0.001). Generally, the eczema group was more sensitized to the panel of allergens compared to the asthma group. Individuals with asthma and those with eczema showed different sensitization profiles to HDM. These findings highlighted possible mechanisms for different manifestation of allergy.

Serine protease activity of Cur l 1 from Curvularia lunata augments Th2 response in mice

RATIONALE

Studies with mite allergens demonstrated that proteolytic activity augments allergic airway inflammation. This knowledge is limited to few enzyme allergens.

OBJECTIVE

The objective of this study is to investigate the effect of serine protease Cur l 1 from Curvularia lunata in airway inflammation/hyper-responsiveness.

METHODS

Cur l 1 was purified and inactivated using a serine protease inhibitor. Balb/c mice were sensitized with enzymatically active Cur l 1 or C. lunata extract. Sensitized mice were given booster dose on day 14 with active or inactivated Cur l 1. Intranasal challenge was given on day 28, 29, and 30. Airway hyper-responsiveness was measured by plethysmography. Blood, bronchoalveolar lavage fluid (BALF), spleen, and lungs from mice were analyzed for cellular infiltration, immunoglobulins, and cytokine levels.

RESULTS

Mice challenged with enzymatically active Cur l 1 demonstrated significantly higher airway inflammation than inactive Cur l 1 group mice (p < 0.01). There was a significant difference in serum IgE and IgG1 levels among mice immunized with active Cur l 1 and inactive Cur l 1 (p < 0.01). IL-4 and IL-5 were higher in BALF and splenocyte culture supernatant of active Cur l 1 than inactive Cur l 1 mice. Lung histology revealed increased eosinophil infiltration, goblet cell hyperplasia and mucus secretion in active group.

CONCLUSION

Proteolytic activity of Cur l 1 plays an important role in airway inflammation and the inactivated Cur l 1 has potential to be explored for immunotherapy.

Protease activity of allergenic pollen of cedar, cypress, juniper, birch and ragweed

BACKGROUND

Pollen is an important trigger of allergic rhinitis, conjunctivitis, and/or asthma, and an exacerbating factor in atopic dermatitis. Although it is proposed that protease activity from allergen sources, such as mites, enhances allergenicity, little information is available on that from relevant allergenic pollens such as Japanese cedar and Japanese cypress pollens, which are the major cause of pollinosis in Japan.

METHODS

We analyzed the protease activities derived from allergenic pollen of Japanese cedar, Japanese cypress, and Rocky mountain juniper, which belong to the Cupressaceae/Taxodiaceae family, and white birch and short ragweed, using synthetic substrates and class-specific inhibitors.

RESULTS

We found that the pollen of the three members of the Cupressaceae/Taxodiaceae family contained serine protease activity, that the pollen of white birch and short ragweed contained not only serine protease activity but also cysteine protease activity, that all five types of pollen tested contained at least one other type of serine protease, whose sensitivity to a serine protease-specific inhibitor was relatively low, and that the content and releasability of the pollen-derived proteases differed according to the plant families.

CONCLUSIONS

Clinically relevant allergenic pollens tested in the present study can release serine and/or cysteine endopeptidases. Information on the spectrum of the endopeptidase activities from these allergenic pollen grains will be useful for investigating their contribution to the pathogenesis of allergies.

Upregulation of the release of granulocyte-macrophage colony-stimulating factor from keratinocytes stimulated with cysteine protease activity of recombinant major mite allergens, Der f 1 and Der p 1

BACKGROUND

Although exposure to mite allergens is an important risk factor for the production of IgE and is associated with various allergic diseases, there has been uncertainty as to the route of exposure by which sensitization occurs. Cystatin A is a skin-derived dominant inhibitor against proteolytic activity of major mite allergens, Der f 1 and Der p 1, and blocks the upregulation of IL-8 release from human keratinocytes stimulated with the allergens. We analyzed whether the stimulation of keratinocytes with the allergens upregulates the release of granulocyte-macrophage colony-stimulating factor (GM-CSF), which has many actions relevant to allergic diseases including atopic dermatitis, and if so, whether cystatin A can block this process.

METHODS

Normal human keratinocytes and the human keratinocyte cell line HaCaT were stimulated with recombinant group 1 allergens in the absence or presence of cystatin A.

RESULTS

Stimulation with the recombinant allergens upregulated the release of GM-CSF from normal human keratinocytes in a culture with high calcium concentration and HaCaT cells, which could be inhibited by the addition of cystatin A. The allergens exhibiting proteolytic activity did not digest cystatin A. Proteolytic activity of recombinant Der f 1 was partially regenerated after incubation with keratinocytes even without preactivation by L-cysteine.

CONCLUSION

Proteolytic activity of recombinant Der f 1 and Der p 1 upregulates GM-CSF and IL-8 release from keratinocytes in vitro, suggesting possible contributions to sensitization through the skin and the perpetuation of atopic dermatitis, as well as a homeostatic role for cystatin A against inflammation of the skin.