Allergenic characterization of a novel allergen, homologous to chymotrypsin, from german cockroach

Airborne indoor allergen serine proteases and their contribution to sensitisation and activation of innate immunity in allergic airway disease

Common airborne allergens (pollen, animal dander and those from fungi and insects) are the main triggers of type I allergic disorder in the respiratory system and are associated with allergic rhinitis, allergic asthma, as well as immunoglobulin E (IgE)-mediated allergic bronchopulmonary aspergillosis. These allergens promote IgE crosslinking, vasodilation, infiltration of inflammatory cells, mucosal barrier dysfunction, extracellular matrix deposition and smooth muscle spasm, which collectively cause remodelling of the airways. Fungus and insect (house dust mite and cockroaches) indoor allergens are particularly rich in proteases. Indeed, more than 40 different types of aeroallergen proteases, which have both IgE-neutralising and tissue-destructive activities, have been documented in the Allergen Nomenclature database. Of all the inhaled protease allergens, 85% are classed as serine protease activities and include trypsin-like, chymotrypsin-like and collagenolytic serine proteases. In this article, we review and compare the allergenicity and proteolytic effect of allergen serine proteases as listed in the Allergen Nomenclature and MEROPS databases and highlight their contribution to allergic sensitisation, disruption of the epithelial barrier and activation of innate immunity in allergic airways disease. The utility of small-molecule inhibitors of allergen serine proteases as a potential treatment strategy for allergic airways disease will also be discussed.

Intestinal Parasites Associated with American Cockroach (Periplaneta americana) in Akure, Ondo State, Nigeria

American cockroach (Periplaneta americana) has been implicated as mechanical vector of parasites of humans and animals. Therefore, this study aimed to identify and determine the prevalence of human intestinal parasites associated with the body surface and gut of P. americana. A total of 221 cockroaches which include 104 males and 117 females were collected from household kitchen, toilet area and canteen after which they were brought to laboratory for study. The body surface of the cockroach was washed with 5 ml normal saline solution to remove external parasites on the body surface for examination and later rinsed with 70% alcohol and dried before dissecting. The cockroach was dissected to examine internal parasites. Eleven parasites were recovered and identified, these include Ascaris lumbricoides (51.58%), Strongyloides stercoralis (48.42%) Trichuris trichiura (52.49%), Enterobius vermicularis (37.10%), Taenia spp (14.93%), Toxocara (31.67%), Ancylostoma spp (34.84%), Necator americanus (53.39%), and Diphylidium spp (66.23%) Balantidium coli (66.52%). The parasites were recorded both on the body surface and gut of the cockroach. There is no significant difference (p > 0.05) between parasites infection rate comparing both sexes; though, female cockroach having a higher infection rate (91.45%) than male (81.5%). Cockroach collected from toilets carried more parasites (96.34%) as compared to those from restaurants/canteen (89.71%) and household kitchens (81.69%). All parasites encountered were pathogenic to human and animals. This study has revealed that P. americana can act as mechanical vector by transporting and transmitting these parasites easily to man and animal. Good sanitary practices, reinforcement of worms' eradication programs, and the fight against these insects remain a necessity to contain the menace of parasites burden and cockroach control.

Two Antenna-Enriched Carboxylesterases Mediate Olfactory Responses and Degradation of Ester Volatiles in the German Cockroach Blattella germanica

Insects have evolved an extremely sensitive olfactory system that is essential for a series of physiological and behavioral activities. Some carboxylesterases (CCEs) comprise a major subfamily of odorant-degrading enzymes (ODEs) playing a crucial role in odorant signal inactivation to maintain the odorant receptor sensitivity. In this study, 93 CCEs were annotated in the genome of the German cockroach Blattella germanica, a serious urban pest. Phylogenetic and digital tissue expression pattern analyses identified two antenna-enriched CCEs, BgerCCE021e3 and BgerCCE021d1, as candidate ODEs. RNA interference (RNAi)-mediated knockdown of BgerCCE021e3 and BgerCCE021d1 resulted in partial anosmia with experimental insects exhibiting reduced attraction to ester volatile resources and slower olfactory responses than controls. Furthermore, enzymatic conversion of geranyl acetate by crude male antennal extracts from BgerCCE021e3 and BgerCCE021d1 RNAi insects was also significantly reduced. Our results provide evidence for CCE function in German cockroach olfaction and provide a basis for further exploring behavioral inhibitors that target olfactory-related CCEs.

First report of Lophomonas spp. in German cockroaches (Blattella germanica) trapped in hospitals, northern Iran

Cockroaches are considered to be important reservoirs for protozoan and helminth parasites,particularly an emerging Lophomonas spp., protozoan parasite. German cockroaches, Blattella germanica (B. germanica), are domestic pest distributed worldwide. However, little information is available regarding the burden of Lophomonas spp. infestation among domestic cockroach population worldwide. The present study investigated parasitic agents, emphasizing Lophomonas spp. infestation among B. germanica in northern Iran. During spring and summer 2018, a total of 496 adults B. germanica (265 males and 231 females) were trapped by hand and glass traps from the teaching hospitals in Mazandaran, Sari, northern Iran. All cockroaches were identified using taxonomic keys. Each cockroaches was anesthetized with chloroform and the alimentary tract removed. Each section was smeared onto a glass slide. All the smears were examined under light microscopy to determine the presence of the parasites. Ten genera of parasites were identified from the trapped B. germanica; overall, 233 (47%) were found to be positive for helminths (n = 135) and protozoa (n = 98). The helminths included Aspiculuris tetraptera egg (67/233, 28.7%), Oxiuros sp. (39/233; 16.7%), Dentostomella translucida (17/233; 7.3%), and nematodes Ova (12/233; 5.2%). The protozoan parasites identified Gregarina sp. (61/233; 26.2%), Entamoeba sp. (19/233; 8.2%), Blastocystis sp. (5/233; 2.1%), Lophomonas (4/233; 1.7%), Nyctotherus sp. (4/233; 1.7%), unclassified flagella (5/233; 2.1%). Lophomonas spp. was detected within the gut of B. germanica, for the first time, in Iran. It has previously been identified in the gut of cockroaches a long time ago, however, this is the first attempt to detect Lophomonas in cockroaches housing in hospitals. Thereby, it possibly presenting pose a serious respiratory infection risk for patients and health care personnel.

Silencing the odorant coreceptor (Orco) disrupts sex pheromonal communication and feeding responses in Blattella germanica: toward an alternative target for controlling insect-transmitted human diseases

BACKGROUND

The German cockroach, Blattella germanica, is one of the most severe pests of urban and rural areas. High-throughput genetic screening approaches indicate that the olfactory system of this pest is extremely powerful because it has an extensive array of olfactory receptor genes compared with many other insect species. Several of these genes have been identified previously, but their functions have not yet been characterized.

RESULTS

This study describes the sequence of five transcriptomes of B. germanica adult male antennae, female antennae, maxillary palps, legs, and fifth-instar nymph antennae to investigate expression patterns of odorant receptors (ORs). Approximately 90% of ORs were found to be the most highly expressed genes in adult or nymph antennae. Additionally, every OR requires an odorant co-receptor (Orco) to become fully functional, and this was selected and successfully inhibited by injection of the corresponding double-stranded (ds)RNA targeting the Orco. A strong RNA interference (RNAi) effect was observed in which > 75% of Orco messenger RNA (mRNA) was clearly suppressed after 72 h of treatment. Olfactory behavioral assays showed that Orco-impaired B. germanica respond more slowly and show less attraction to one volatile sex pheromone and food resources compared with a control group.

CONCLUSION

The results show that Orco plays a pivotal role in both sex pheromone and food-seeking olfactory processes, and provide an alternative genetic technique for controlling this urban pest species by olfactory disruption. © 2020 Society of Chemical Industry.

Novel Allergen Discovery through Comprehensive De Novo Transcriptomic Analyses of Five Shrimp Species

Shellfish allergy affects 2% of the world's population and persists for life in most patients. The diagnosis of shellfish allergy, in particular shrimp, is challenging due to the similarity of allergenic proteins from other invertebrates. Despite the clinical importance of immunological cross-reactivity among shellfish species and between allergenic invertebrates such as dust mites, the underlying molecular basis is not well understood. Here we mine the complete transcriptome of five frequently consumed shrimp species to identify and compare allergens with all known allergen sources. The transcriptomes were assembled de novo, using Trinity, from raw RNA-Seq data of the whiteleg shrimp (Litopenaeus vannamei), black tiger shrimp (Penaeus monodon), banana shrimp (Fenneropenaeus merguiensis), king shrimp (Melicertus latisulcatus), and endeavour shrimp (Metapenaeus endeavouri). BLAST searching using the two major allergen databases, WHO/IUIS Allergen Nomenclature and AllergenOnline, successfully identified all seven known crustacean allergens. The analyses revealed up to 39 unreported allergens in the different shrimp species, including heat shock protein (HSP), alpha-tubulin, chymotrypsin, cyclophilin, beta-enolase, aldolase A, and glyceraldehyde-3-phosphate dehydrogenase (G3PD). Multiple sequence alignment (Clustal Omega) demonstrated high homology with allergens from other invertebrates including mites and cockroaches. This first transcriptomic analyses of allergens in a major food source provides a valuable resource for investigating shellfish allergens, comparing invertebrate allergens and future development of improved diagnostics for food allergy.

Domiciliary Cockroaches as Carriers of Human Intestinal Parasites in Lagos Metropolis, Southwest Nigeria: Implications for Public Health

BACKGROUND

Domiciliary cockroaches are obnoxious pests of significant medical importance. We investigated the prevalence of human intestinal parasites in cockroaches and its attendant public health importance.

METHODS

Overall, 749 cockroaches (Periplaneta americana, 509, Blattella germanica, 240) caught by trapping from 120 households comprising 3 different housing types in Somolu, Lagos metropolis, southwest Nigeria, in 2015 were screened for human intestinal parasites using standard parasitological techniques.

RESULTS

The prevalence of human intestinal parasites in cockroaches was 96.4%. There was no statistically significant difference (P> 0.05) in parasite prevalences between P. americana (95.7%) and B. germanica (97.9%). Parasite species identified and their prevalence were as follows: Entamoeba histolytica/dispar (44.1%), E. coli (37.8%), Giardia lamblia (18.7%), Cryptosporidium sp. (13.8%), Ascaris lumbricoides (61.3%), Trichuris trichiura (55.8%), hookworms (11.6%), Strongyloides stercoralis (11.7%), Taenia/Echinococcus spp. (10.5%), Enterobius vermicularis (17.2%) and Hymenolepis nana (11.6%). Parasite prevalence and burdens varied with housing type; the prevalence was significantly higher statistically (P< 0.05) in cockroaches from low-cost bungalow, LCB (100%) and low-cost, 2-storey, LC2-S (100%) houses than in medium-cost flats, MCF (81.3%). Parasite burdens were also significantly higher statistically (P< 0.05) in cockroaches from LCB or LC2-S than in cockroaches from MCF. Parasite prevalences between cockroach gut and body surfaces were not statistically significant (P> 0.05) but mean parasite burdens in gut were significantly higher statistically (P< 0.05) than on body surfaces.

CONCLUSION

Cockroaches types carry transmissive stages of human intestinal parasites and may act as reservoirs and potential mechanical vectors for disease transmission.

dNP2-ctCTLA-4 inhibits German cockroach extract-induced allergic airway inflammation and hyper-responsiveness via inhibition of Th2 responses

German cockroaches are major household allergens that can trigger allergic airway inflammatory diseases with sensitive T-cell responses. Although the use of immune modulatory biologics, such as antibodies, to mediate allergic responses has recently been examined, only systemic administration is available because of the size limitations on intranasal administration. Here we utilized a cell-permeable peptide, dNP2, to deliver the cytoplasmic domain of cytotoxic T-lymphocyte antigen-4 (ctCTLA-4) through the airway epithelium to modulate Th2 responses in a German cockroach extract (GCE)-induced allergic airway inflammation model. The intranasal delivery efficiency of the dNP2-dTomato protein to the lungs was higher in GCE-induced asthmatic lung parenchymal cells compared to the sham cells. Intranasal administration of the dNP2-ctCTLA-4 protein inhibited airway hyper-responsiveness and reduced airway inflammation and remodeling, including goblet cell metaplasia and collagen deposition around the bronchi. The number of infiltrated cells, including eosinophils, and the levels of IL-4, IL-5, IL-13 and IFN-γ in the lungs were significantly reduced, presumably owing to inhibition of Th2 differentiation. However, intranasal administration of CTLA4-Ig did not inhibit airway inflammation. These results collectively suggest that dNP2-ctCTLA-4 is an efficient intranasally applicable candidate biologic for treating allergic asthma.

New Insights into Cockroach Allergens

PURPOSE OF REVIEW

This review addresses the most recent developments on cockroach allergen research in relation to allergic diseases, especially asthma.

RECENT FINDINGS

The number of allergens relevant to cockroach allergy has recently expanded considerably up to 12 groups. New X-ray crystal structures of allergens from groups 1, 2, and 5 revealed interesting features with implications for allergen standardization, sensitization, diagnosis, and therapy. Cockroach allergy is strongly associated with asthma particularly among children and young adults living in inner-city environments, posing challenges for disease control. Environmental interventions targeted at reducing cockroach allergen exposure have provided conflicting results. Immunotherapy may be a way to modify the natural history of cockroach allergy and decrease symptoms and asthma severity among sensitized and exposed individuals. The new information on cockroach allergens is important for the assessment of allergen markers of exposure and disease, and for the design of immunotherapy trials.

Cockroach allergen exposure and risk of asthma

Cockroach sensitization is an important risk factor for the development of asthma. However, its underlying immune mechanisms and the genetic etiology for differences in allergic responses remain unclear. Cockroach allergens identification and their expression as biologically active recombinant proteins have provided a basis for studying the mechanisms regarding cockroach allergen-induced allergic sensitization and asthma. Glycans in allergens may play a crucial role in the immunogenicity of allergic diseases. Protease-activated receptor (PAR)-2, Toll-like receptor (TLR), and C-type lectin receptors have been suggested to be important for the penetration of cockroach allergens through epithelial cells to mediate allergen uptake, dendritic cell maturation, antigen-presenting cell (APC) function in T-cell polarization, and cytokine production. Environmental pollutants, which often coexist with the allergen, could synergistically elicit allergic inflammation, and aryl hydrocarbon receptor (AhR) activation and signaling may serve as a link between these two elements. Genetic factors may also play an important role in conferring the susceptibility to cockroach sensitization. Several genes have been associated with cockroach sensitization and asthma-related phenotypes. In this review, we will discuss the epidemiological evidence for cockroach allergen-induced asthma, cockroach allergens, the mechanisms regarding cockroach allergen-induced innate immune responses, and the genetic basis for cockroach sensitization.

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

Purpose

CpG oligodeoxynucleotide (CpG-ODN), a TLR9 agonist, activates innate immunity and induces Th1 response. Although the immune modulatory effect of CpG-ODN has been extensively studied, its function in cockroach extract-induced allergic asthma has not been studied. Here, we investigated the inhibitory function of CpG-ODN in cockroach extract-induced asthma in mice with different treatment schemes.

Methods

Scheme 1: BALB/C mice were intra-nasally co-administered by cockroach extract and CpG-ODN twice a week for 3 weeks; Scheme 2: The mice were intra-nasally pre-treated with CpG-ODN at day 0 and cockroach allergen challenge was performed from day 3 as in scheme 1. Scheme 3: Cockroach allergen challenge was performed as in scheme 1 and CpG-ODN was post-treated at day 21. Then, BAL cell count, flow cytometric analysis of alveolar macrophages, regulatory T cells, and lung tissue histology, Th1 and Th2 cytokines, serum IgE, cockroach specific IgE, IgG1/IgG2a ratio, and airway hyper-responsiveness were evaluated.

Results

Mice with repeated intra-nasal exposure to CpG-ODN showed a dramatic decrease in eosinophilic inflammation, goblet cell hyperplasia, and airway hyper-responsiveness with reduction of IL-13, IL-5, and serum IgE, cockroach specific IgE and IgG1/IgG2a ratio. This inhibitory function might be related to the up-regulation of IL-10 and CD4⁺Foxp3⁺ regulatory T cells in the lung. Interestingly, one-time challenge of CpG-ODN either prior or posterior to cockroach extract exposure could modulate airway inflammation and hyper-responsiveness via increase of Th1 response.

Conclusions

Collectively, our data suggest that CpG-ODN treatment modulates Th2 inflammation in the lung by induction of regulatory T cells or Th1 response in a cockroach-induced asthma model.