Blocking of protease allergens with inhibitors reduces allergic responses in allergic rhinitis and other allergic diseases

Nasal instillation of povidone-iodine ameliorates ongoing mucosal inflammation in a pre-sensitized murine model of Der p1-induced allergic rhinitis

BACKGROUND

Interleukin (IL)-33, when cleaved into smaller fragments by proteases, becomes hyperactive, contributing to allergic inflammation. Povidone-iodine (PVP-I) is an iodine-based compound that exhibits antimicrobial properties and inhibits proteases. This study aimed to investigate whether PVP-I treatment inhibits IL-33 cleavage, improves allergic rhinitis (AR) symptoms, and suppresses allergic inflammation in a mouse model.

METHODS

In vitro experiments using full-length recombinant human IL-33 and allergens, including house dust mites or Dermatophagoides pteronyssinus 1, were conducted using western blotting. Fifty BALB/c mice were divided into five groups: control (CON), AR with phosphate-buffered saline treatment (AR), PVP-I treatment (AR + PVP), trans-epoxysuccinyl-L-leucylamido(4-guanidino)butane (E64) treatment (AR + E64), and dexamethasone treatment (AR + Dexa). Nasal symptom scores, including rubbing and sneezing, were measured. The cytokine levels in the nasal lavage fluid (NLF) and the concentration of immunoglobulins in the blood serum were assessed. Nasal mucosa from each group was used for reverse transcriptase-polymerase chain reaction (RT-PCR) and histological analyses were conducted.

RESULTS

PVP-I treatment reduced nasal symptoms, suppressed allergic inflammation, and decreased the levels of IL-33, IL-5, and IL-13 in the NLF and total immunoglobulin E (IgE) and specific IgE in the serum. Histopathological analysis revealed a reduction in the number of eosinophils and goblet cells in the nasal mucosa of the AR + PVP group when compared to the AR group. RT-PCR and immunofluorescence staining confirmed the downregulation of genes and proteins associated with allergic inflammation.

CONCLUSIONS

These findings suggest that nasal irrigation with PVP-I may be a promising therapeutic option for managing AR by inhibiting IL-33 activation and suppressing allergic inflammation.

Airway Epithelial Dynamics in Allergy and Related Chronic Inflammatory Airway Diseases

Allergic rhinitis, chronic rhinosinusitis, and asthma are highly prevalent, multifactorial chronic airway diseases. Several environmental and genetic factors affect airway epithelial dynamics leading to activation of inflammatory mechanisms in the airways. This review links environmental factors to host epithelial immunity in airway diseases. Understanding altered homeostasis of the airway epithelium might provide important targets for diagnostics and therapy of chronic airway diseases.

Extracts of different pollen species and their effect on human tear fluid and an epithelial cell line

PURPOSE

Hazelnut and birch pollen are known to destroy tear film components and attack ocular surface cells. We investigated further pollen species from different plant families, whether they show similar effects on human tear fluid and an epithelial cell line in vitro, to provide a broad basis for further research on pollen reactions affecting the tear film and ocular surface.

MATERIALS AND METHODS

Regional pollen species from different plant families (Adoxaceae, Betulaceae, Fagaceae, Juglandaceae, Malvaceae, Oleaceae, Pinaceae, Plantaginaceae, Poaceae, Salicaceae, Sapindaceae) were collected. Their proteolytic activity was evaluated by Zymography. Human tear fluid and cells of an epithelial cell line were incubated with pollen extracts. Tear fluid was analyzed by Polyacrylamide gel electrophoresis (PAGE). Cytomorphology was assessed microscopically and cell viability by proliferation (MTS), water-soluble tetrazolium (WST-1) assay and the impedance-based xCELLigence real-time analysis (RTCA).

RESULTS

Zymography revealed significant protease activity and PAGE showed the degradation of tear proteins by different pollen species. Cells incubated with pollen extracts presented dose- and time-dependent cytomorphological changes. MTS, WST-1, and RTCA revealed cytostatic as well as cytotoxic effects of pollen extracts.

CONCLUSIONS

Pollen species from different plant families exert proteolytic activity and degrade human tear fluid as well as epithelial cells, which may play a crucial role in the pathogenesis of allergic and non-allergic reactions affecting the ocular surface.

Human cystatin SN is an endogenous protease inhibitor that prevents allergic rhinitis

BACKGROUND

Protease allergens disrupt epithelial barriers to exert their allergenicity. Cystatin SN (encoded by CST1) is an endogenous cysteine protease inhibitor upregulated in nasal epithelia in patients with allergic rhinitis (AR).

OBJECTIVE

We sought to investigate the protective effect of human cystatin SN on AR symptoms using pollen-induced AR mouse models.

METHODS

We performed an in vitro protease activity assay to evaluate the effect of recombinant human cystatin SN (rhCystatin SN) on Japanese cedar (JC) or ragweed proteases. A human nasal epithelial cell line, RPMI 2650, was used to examine tight junction (TJ) disruption in vitro. Mice were sensitized and nasally challenged with JC or ragweed pollens with or without rhCystatin SN to examine the effect of rhCystatin SN on AR symptoms and the epithelial barrier in vivo. Because mice lack CST1, we generated transgenic (Tg) mice expressing human CST1 under control of its genomic control region (hCST1-Tg mice) to examine the role of cystatin SN in physiologically expressed conditions.

RESULTS

rhCystatin SN inhibited JC but not ragweed protease activities and prevented JC-induced but not ragweed-induced TJ disruption in vitro. Exogenous administration of rhCystatin SN ameliorated JC-induced but not ragweed-induced sneezing and nasal TJ disruption in vivo. Furthermore, hCST1-Tg mice showed decreased JC-induced but not ragweed-induced sneezing symptoms and nasal TJ disruption compared with wild-type mice.

CONCLUSION

Human cystatin SN suppresses AR symptoms through inhibiting allergen protease activities and protecting the nasal TJ barrier in an allergen-specific manner. We propose that upregulation of nasal endogenous protease inhibitors, including cystatin SN, is a novel therapeutic strategy for protease allergen-induced AR.

Airway epithelial barrier dysfunction in the pathogenesis and prognosis of respiratory tract diseases in childhood and adulthood

The lungs are in direct contact with the environment through the tubular structure that constitutes the airway. Starting from the nasal orifice, the airway is exposed to foreign particles including infectious agents, allergens, and other substances that can damage the airways. Therefore, the airway must have a functional epithelial barrier both in the upper and lower airways to protect against these threats. As with the skin, it is likely that the pathogenesis of respiratory diseases is a consequence of epithelial barrier defects in these airways. The characteristics of this system, starting from the beginning of life and extending into maturing and aging, determine the prognosis of respiratory diseases. In this article, we discuss the pathogenesis, clinical phenotype, and prognosis of respiratory diseases from newborns to adulthood in the context of epithelial barrier function and dysfunction.

Identification of Proteases and Protease Inhibitors in Allergenic and Non-Allergenic Pollen

Pollen is one of the most common causes of allergy worldwide, making the study of their molecular composition crucial for the advancement of allergy research. Despite substantial efforts in this field, it is not yet clear why some plant pollens strongly provoke allergies while others do not. However, proteases and protease inhibitors from allergen sources are known to play an important role in the development of pollen allergies. In this study, we aim to uncover differences in the transcriptional pattern of proteases and protease inhibitors in Betula verrucosa and Pinus sylvestris pollen as models for high and low allergenic potential, respectively. We applied RNA sequencing to Betula verrucosa and Pinus sylvestris pollen. After de-novo assembly we derived general functional profiles of the protein coding transcripts. By utilization of domain based functional annotation we identified potential proteases and protease inhibitors and compared their expression in the two types of pollen. Functional profiles are highly similar between Betula verrucosa and Pinus sylvestris pollen. Both pollen contain proteases and inhibitors from 53 and 7 Pfam families, respectively. Some of the members comprised within those families are implicated in facilitating allergen entry, while others are known allergens themselves. Our work revealed several candidate proteins which, with further investigation, represent exciting new leads in elucidating the process behind allergic sensitization.

Barrier function of the nasal mucosa in health and type-2 biased airway diseases

The mucosal lining of the upper airways represents the outer surface of the body to the ambient air and its contents and is prepared for it as the first line of defense. Apart from the well-described physical barrier and the mucociliary clearance, a variety of systems, including the airway microbiome, antimicrobial proteins, damage-associated molecular patterns, innate lymphoid cells, epithelial-derived cytokines and chemokines, and finally the adaptive immune system, as well as eosinophils as newly appreciated defense cells form different levels of protection against and response to any possible intruder. Of interest especially for allergic airway disease, mucosal germs might not just elicit a classical Th1/Th17-biased inflammatory response, but may directly induce a type-2 mucosal inflammation. Innovative therapeutic interventions may be possible at different levels also; however, whether modulations of the innate or adaptive immune responses will finally be more successful, and how the correction of the adaptive immune response might impact on the innate side, will be determined in the near future.

Effect of proteolytic activity of Epicoccum purpurascens major allergen, Epi p 1 in allergic inflammation

Enzymes play an important role in inducing airway inflammation, but knowledge is limited to few proteins. This study was carried out to assess the role of Epi p 1, a serine protease of Epicoccum purpurascens, in inducing allergy and inflammation in a murine model. Balb/c mice were sensitized with Epi p 1 active protease (EAP) or Epicoccum extract. Subsequently, Epi p 1 sensitized mice were boosted on day 14 with EAP or inactivated protease (EIAP). Three intranasal challenges were given and mice were killed to obtain blood, bronchoalveolar lavage fluid (BALF), spleen and lung tissues. Cellular airways infiltration, immunoglobulin E (Ig)E titres and cytokine levels in BALF and splenocyte culture supernatant were compared. Mice immunized with EAP had higher Epi p 1-specific serum IgE and IgG1 than EIAP immunized mice (P < 0.01). There was a twofold difference in the number of eosinophils in BALF of EAP mice and EIAP mice (P < 0.01). A similar trend was recorded for eosinophil peroxidase activity (P < 0.05), indicating the role of proteolytic activity in inducing inflammation. Further, lung histology revealed increased leucocyte infiltration and airway narrowing, with higher inflammation scores in the EAP group than in the EIAP group. The lungs of EAP mice showed increased mucus and goblet cell metaplasia. Interleukin (IL)-4 and IL-5 levels were higher in BALF and splenocyte culture supernatant of EAP mice than in EIAP mice (P < 0.05), indicating a T helper 2 response. Proteolytic activity of Epi p 1 plays an important role in inducing allergic inflammation. The enzymatically inactive form may be investigated for immunotherapy.

Intranasal Aspergillus fumigatus exposure induces eosinophilic inflammation and olfactory sensory neuron cell death in mice

OBJECTIVE

To determine the effects of eosinophilic inflammation on olfactory sensory neuron cell death.

STUDY DESIGN

Mice were sensitized to intranasal Aspergillus fumigatus extract and subsequently challenged acutely or chronically with the same allergen. The olfactory neuroepithelium was assessed for immunohistochemical evidence of apoptosis and inflammation.

RESULTS

Sensitized mice challenged with allergen demonstrated elevated eosinophil infiltration of the respiratory and olfactory mucosae, with olfactory sensory neuron apoptosis. Remarkably, massive neuronal apoptosis without eosinophil infiltration occurred in nonsensitized mice after a single dose of extract.

CONCLUSION

Intranasal sensitization with A fumigatus results in a model with multifactorial effects. Protocols using A fumigatus to induce allergic rhinitis may need modification to allow confident interpretation.

SIGNIFICANCE

Fungal allergens may contribute to anosmia through the induction of olfactory sensory neuron apoptosis, with and without prior sensitization.