Clinical Relevance of Lepidoglyphus destructor Sensitisation in Allergic Rhinitis: Nasal Provocation Test as in vivo Assessment

BACKGROUND

Dust mites are the leading cause of respiratory allergic diseases worldwide. Allergy to storage mites (SMs) has mostly been related to occupational exposures. However, recent studies have shown that sensitisation to SM, such as Lepidoglyphus destructor (Lep d), is of considerable importance also in urban populations, with high prevalence in dust samples of domestic environments. Co-sensitisation between house dust mites (HDMs) and SM is now regarded as very frequent in some regions, and cross-reactivity between them seems to be narrow. Therefore, SM allergenic capacity is increasingly a subject of study. The nasal provocation test (NPT), as an in vivo technique, could be considered the gold standard for the clinical relevance assessment of an allergen, in polysensitised rhinitis patients.

OBJECTIVE

The objective of this study was to analyse the clinical relevance of the SM Lep d, by assessing the relationship between in vivo sensitisation and expression of allergic respiratory disease in an urban setting.

PATIENTS AND METHODS

In our study, we enrolled a total of 32 allergic patients with rhinitis (with or without asthma) with proven sensitisation by skin prick test (SPT) and specific IgE (sIgE) to HDMs and/or SM. Patients underwent NPT with Lep d using subjective (Lebel Symptom Score Scale) and objective measurements (peak nasal inspiratory flow [PNIF]) for assessment of nasal response.

RESULTS

Most of the patients with positive SPT and sIgE to Lep d had a positive NPT (24/27; 89%). True Lep d allergy, assessed by a positive NPT, could be predicted by a SPT wheal size >9.7 mm and a sIgE >0.42 kUA/L, with 100%/95.7% sensitivity and 75.0%/83.3% specificity, respectively. Co-sensitisation between Lep d and Der p was high, 75.0%. Asthma was more frequent in the positive Lep d NPT group (54 vs. 12%, p < 0.05). Significantly more patients from this group reported physical exercise, nonspecific irritants, and respiratory infections as relevant triggers of respiratory symptoms (p < 0.01-p < 0.05).

CONCLUSIONS

To our knowledge, this is the first study to show that sensitisation to Lep d may have clinical relevance in a non-occupational setting. In this group, there seems to be a relationship between allergy to Lep d and severity of respiratory disease, with more bronchial inflammation, when comparing with mite-allergic patients sensitised only to HDM. Therefore, the authors consider that sensitisation to Lep d should be considered when assessing and treating allergic respiratory disease in urban environments.

Kill rate as a tool in efficiency evaluation of Neoseiulus californicus (Acari: Phytoseiidae) mass reared on factitious food

The predatory mites of the Phytoseiidae family are crucial biological control agents widely utilized in biological pest management targeting phytophagous mites and insects. Key factors in these control strategies are that phytoseiids must be able to find their main target prey and to maintain high populations and efficacy. To reduce expenses and time-consuming production methods of mass rearing of phytoseiids, pollen and other factitious (i.e., non-natural/nontarget) hosts need to be present as an alternative food for predatory mite populations. The mass-rearing possibilities of these predators on alternative food sources, such as astigmatid mites (i.e., house and stored mites) and pollen, must be evaluated not only by the cost of rearing settings but on the basis of their efficiency maintenance in killing prey. The pest kill rate (km) is the average daily lifetime killing of the pest by the natural enemy under consideration and can represent a useful indicator for phytoseiids efficacy to rank them as BCAs on the basis of their effective killing/predation on target prey. In this study, we evidenced that 2 astigmatid mites, Glycyphagus domesticus (De Geer) and Lepidoglyphus destructor (Schrank), and Quercus ilex L. pollen can be successfully adopted as substitute food sources for mass rearing of the phytoseiid Neoseiulus californicus (MgGregor); then, we determined that these populations of BCAs maintained a consistent km at new/first impact on the main target pest, Tetranychus urticae Koch.

Serodominance Profile in a Dust Mite Complex Region

BACKGROUND/OBJECTIVE

The objective of this study was to describe the molecular sensitization profile of mite allergy in an area with a high environmental exposure of house dust mites (HDM) and storage mites.

METHODS

Skin prick tests were performed with standardized extracts (DIATER, Madrid, Spain). A specific commercial molecular panel (MADx) for Dermatophagoides pteronyssinus (Dpt), Dermatophagoides farinae (Dfar), Lepidoglyphus destructor (Ldt), Tyrophagus putrescentiae (Tput), and Blomia tropicalis (Blot) was correlated with clinical parameters in Galician (northwestern of Spain) HDM allergic patients.

RESULTS

Fifty patients (60% female) met the inclusion and exclusion criteria. All of the patient's present rhinitis (50), 28% (14) rhinitis and asthma, and 18% (9) atopic dermatitis (AD). Hundred patients had a positive prick test for Dpt, followed by Dfar (92%), Ldt and Tput (74%), and Blot (68%). More than 50% recognized specific IgE for Der p 1, Der p 2, reaching 86% in the case of Der p 23. No statistically significant differences in IgE levels were found between patients with/without asthma and those with mild or moderate-severe rhinitis. Der p 7 was higher among rhinitis patients (p value 0.05). AD relative risk (RR) was increased in patients sensitized to Der f 2, Der p 2, and Der p 23. Der p 10 decreases the risk to have AD (RR 0.80).

CONCLUSION

The evaluation of IgE results in a comprehensive panel of allergens allows differentiation of serological reactivity profiles with their clinical expression, to perform an optimal management. Improvements in component resolved diagnosis and more research on the clinical relevance of mite allergens are needed to achieve a genuine diagnosis leading to specific immunotherapy.

[Morphological observation on hypopus of Lepidoglyphus destructor by optical microscope]

Objective To observe the external morphology of Lepidoglyphus destructor hypopus under an optical microscope. Methods The samples were collected in a store of Chinese medicinal herbs in Huainan City in September, 2016, the L. destructor and the hypopus were isolated, and then made of slide specimens. The slide samples were prepared and observed under an optical microscope. Results The L. destructor hypopus and protonymph were found. The inactive hypopus was oval in shape, the feet were not welldeveloped, there was a distinct transverse seam on its back, and there were 2 pairs of genital sensory organs. Conclusion The optical microscopy shows the morphological characteristics of L. destructor hypopus, which can provide the basis for the biological classification and the prevention.

Association Between Asthma and Sensitization to Allergens of Dermatophagoides pteronyssinus

BACKGROUND AND OBJECTIVE

Little is known about the role of molecular diagnosis in house dust mite (HDM) allergy. In this study, we investigated the association between the sensitization profile of adolescent and adult HDM-allergic patients and asthma in a region with high rates of exposure to HDM.

METHODS

We conducted a cross-sectional study of 384 HDM-allergic patients (38.5%, males; median age, 28 years). A total of 368 patients (95.8%) had rhinitis, and 175 (45.6%) had asthma. Specific IgE (sIgE) to Dermatophagoides pteronyssinus, nDer p 1, rDer p 2, and rPen a 1 was measured in all patients. sIgE to Lepidoglyphus destructor was measured in patients (n=301) with a positive skin test result.

RESULTS

Significantly higher concentrations of sIgE to Der p 1 and sIgE to Der p 2 were observed in patients with asthma than in those without asthma. The proportion of asthmatic patients was higher among individuals who reacted (≥0.35 kUA/L) to both Der p 1 and Der p 2 (147/291, 50.5%) than among those who reacted to only 1 allergen (either Der p 1 or Der p 2, 18/55, 32.7%) or neither allergen (10/38, 26.3%, P=.002). Reactivity to both allergens was associated with asthma after adjusting for age and sex (OR, 2.87; 95%CI, 1.32-6.20). Higher concentrations of sIgE to L destructor were observed in patients with asthma than in patients without asthma. Tropomyosin sIgE ≥0.35 kUA/L was detected in only 6 individuals (1.6%).

CONCLUSIONS

L destructor may be a relevant allergen in high-exposure areas. Dual sensitization (ie, IgE to both Der p 1 and Der p 2) may help to identify HDM-allergic patients who are at risk of asthma.

[Survey and morphological observation of Lepidoglyphus destructor in college canteens]

OBJECTIVE

To understand the breeding and morphology of Lepidoglyphus destructor in college canteens in south Anhui Province.

METHODS

The powder and rice on the floor around dough makers, flour bags and rice bags in college canteens were collected and observed under a microscope.

RESULTS

Totally 108 samples were collected, and Acaroid mites were found in 101 of them with a detection rate of 93.52%. Totally 1 527 mites were found with an average breeding density of 1.41/g. Under the light microscope observed, the L. destructor's four pairs of legs were tapering from tarsus. The back setae were stiff and the ventral setae were smooth and relatively short. The internal vertical seta was longer than the top of the chelicera. Dorsal seta d₃, d₄, lateral seta l₃ and sacral inner hair sai were the longest. The female mites were bigger than the male ones, and had more anal seta than male ones. The genital fold of female mites almost connected together, and the front-end had a crescent shaped plate cover.

CONCLUSIONS

The breeding of Acaroid mites in college canteens is serious, and therefore, effective measures should be taken to prevent and control it.