Mite Fecal Pellets Research Articles

The Emperor's Itch.

Standing with his right hand tucked inside his waistcoat, Napoleon I of France looks off in deep thought, in Jacques-Louis David’s 1812 painting Napoleon in His Study. Though this stance appears regal, there are speculations that this iconic pose was merely a facade for his scratching convenience. At a time when scabies ran rampant, it is no surprise that some believe that Napoleon probably had “the itch.” We now know “the itch” is attributed to scabies, which came from the Latin term scabere—“to scratch.” This condition manifests as pruritic rashes in the human host following colonization of the mite Sarcoptes scabiei in the skin as a result of skin-to-skin contact with an infected host. This infestation is classically seen as papules or burrows, which are thread-like tunnels under the skin f i l led with egg cases and mite fecal pellets. When these burrows are not concealed by papular or vesicular lesions, the parasite itself can be seen at the end of the tunnel as a black dot. Giovan Cosimo Bonomo first described the mite in 1687. However, the causal relationship between the mite and the itching symptoms was not elucidated until 1834 when Simon Francois Renucci, a Corsican medical student, used a needle probe to remove a mite from a young female patient with “the itch.” The key component of his procedure was based on the needle technique of Corsican market women: excavating near the vesicle’s center. Our understanding of the disease was furthered by entomologist Kenneth Mellanby, who noted the small mite burden in the scabietic soldiers he studied and established the person-to-person body contact mode of disease transmission. Today, scabies continues to be a problem in impoverished communities and in sexually active, immunosuppressed, or elderly individuals. But was Napoleon’s pose truly attributed to scabies? Reuben Friedman, an American physician, debunked this theory in 1940. He presented some evidence: Napoleon took many sulfur baths, and Empress Josephine was not known to have scabies. What he actually suffered from, Friedman argued, was dermatitis herpetiformis, which is now clearly linked with celiac disease. Blistering rashes accompanied by intense itching and burning are its hallmarks. Was Napoleon’s stance a consequence of his urge to scratch? No one knows for sure. Whether it was scabies or dermatitis herpetiformis, the Emperor’s affliction is a reality for many patients today. Both conditions can be masked by common features of papules, vesicles, and erosions, prompting misdiagnoses. Fortunately, thanks to histological examination, the Emperor’s itch is now an unraveled mystery and treatable affliction.

Identification of Der p 23, a Peritrophin-like Protein, as a New Major Dermatophagoides pteronyssinus Allergen Associated with the Peritrophic Matrix of Mite Fecal Pellets

The house dust mite (HDM) Dermatophagoides pteronyssinus is one of most important allergen sources and a major elicitor of allergic asthma. We screened a D. pteronyssinus expression cDNA library with IgE Abs from HDM allergic patients. A cDNA coding for a new major allergen was isolated, which showed sequence homology to peritrophins, which contain chitin-binding domains and are part of the peritrophic matrix lining the gut of arthropods. The mature Der p 23 allergen was expressed in Escherichia coli as an 8-kDa protein without its hydrophobic leader sequence and purified to homogeneity. It reacted with IgE Abs from 74% of D. pteronyssinus allergic patients (n = 347) at levels comparable to the two major HDM allergens, Der p 1 and Der p 2. Thus, Der p 23 represents a new major D. pteronyssinus allergen. Furthermore, rDer p 23 exhibited high allergenic activity as demonstrated by upregulation of CD203c expression on basophils from D. pteronyssinus allergic patients. Immunogold electron microscopy localized the allergen in the peritrophic matrix lining the midgut of D. pteronyssinus as well as on the surface of the fecal pellets. Thus, we identified a new major D. pteronyssinus allergen as peritrophin-like protein. The high allergenic activity of Der p 23 and its frequent recognition as respiratory allergen may be explained by the fact that it becomes airborne and respirable through its association with mite feces. Der p 23 may be an essential component for diagnosis and specific immunotherapy of HDM allergy.

Identification of Der p 23, a Peritrophin-Like Protein, As a New Major Dermatophagoides Pteronyssinus Allergen Associated with the Peritrophic Matrix of Mite Fecal Pellets

Identification of Der p 23, a Peritrophin-Like Protein, As a New Major Dermatophagoides Pteronyssinus Allergen Associated with the Peritrophic Matrix of Mite Fecal Pellets

Environmental and occupational allergies

Airborne allergens are the major cause of allergic rhinitis and asthma. Daily exposure comes from indoor sources, chiefly at home but occasionally at schools or offices. Seasonal exposure to outdoor allergens, pollens, and molds is another important source. Exposure to unusual substances at work causes occupational asthma, accounting for about 5% of asthma in adults. Indoor and outdoor air pollutants trigger airway inflammation and increase the severity of asthma. Diesel exhaust particles increase the production of IgE antibodies. Identification and reduction of exposure to allergens is a very important part of the management of respiratory allergic diseases. The first section of this chapter discusses domestic allergens, arthropods (mites and cockroaches), molds, and mammals (pets and mice). Indoor humidity and water damage are important factors in the production of mite and mold allergens, and discarded human food items are important sources of proliferation of cockroaches and mice. Means of identifying and reducing exposure are presented. The second section discusses outdoor allergens: pollens and molds. The particular plants or molds and the amount of exposure to these allergens is determined by the local climate, and local pollen and mold counts are available to determine the time and amount of exposure. Climate change is already having an important effect on the distribution and amount of outdoor allergens. The third section discusses indoor and outdoor air pollution and methods that individuals can take to reduce indoor pollution in addition to eliminating cigarette smoking. The fourth section discusses the diagnosis and management of occupational asthma.

Consumption rate of phytonematodes by Pergalumna sp. (Acari: Oribatida: Galumnidae) under laboratory conditions determined by a new method

Although several generalist species of Pergalumna are known to be nematode predators, the potential of oribatid mites as natural enemies of phytonematodes has been underestimated. The objective of this work was to estimate the consumption rate of a Pergalumna sp. when feeding on two major pest nematodes, Meloidogyne javanica and Pratylenchus coffeae, under laboratory conditions. A new method was used, in which live nematodes are offered to mites and subsequently consumption is quantified based on the sclerotized, well preserved structures in the mite's fecal pellets. The assay was evaluated during 5 days, at 25 degrees C and 96% relative humidity, with three replicates for each nematode species. Every replicate consisted of a group of four mites isolated in an arena, to which 400 nematodes were transferred daily. The daily produced fecal pellets were mounted in Hoyer's medium for examination under a microscope. The nematode buccal stylets and cephalic frameworks were counted to estimate the number of nematodes consumed. It was estimated that a single mite daily ingested 18.3 +/- 0.8 (mean +/- SE) M. javanica (J(2) juveniles) or 41.6 +/- 7.2 P. coffeae (juveniles + adults), the maximal daily consumption being 34 M. javanica and 73 P. coffeae. The method showed to be practical, precise and suitable for laboratory studies in which nematophagous mites classified as engulfers are included.

Nitric oxide production by alveolar macrophages in response to house dust mite fecal pellets and the mite allergens, Der p 1 and Der p 2

Background Allergens are frequently found within or attached to particulate material. For example, house dust mite fecal pellets (HDMFP) contain the major mite allergens, exposure to which have been implicated in the development of asthma. Although several studies have examined the ability of purified allergens to generate inflammatory responses, few studies have investigated whether HDMFP per se, are biologically active. Objective Our objective was to examine the ability of whole HDMFP to stimulate nitric oxide (NO) release from alveolar macrophages. Methods The rat alveolar macrophage cell line, NR8383, was exposed to HDMFP, Der p 1, or Der p 2, and nitrite levels in the culture supernatants were measured with the Griess reagent. NO synthase mRNA expression was determined by RT-PCR. Results HDMFP stimulated the production of NO in a dose-dependent and time-dependent manner, with maximum NO levels measured after 48 hours of exposure. Inclusion of polymyxin B did not influence NO production, suggesting that LPS was not responsible for NO production. HDMFP-mediated NO release was down-modulated after treatment with N G-nitro- l-arginine methyl ester (L-NAME), dexamethasone, EDTA, and cysteine, but not heat treatment. Inducible nitric oxide synthase mRNA was observed 3 hours after HDMFP exposure, with maximum levels after 48 hours. Both purified Der p 1 and Der p 2 induced NO production, and inhibition of the cysteine protease activity of Der p 1 had little effect on NO production. Conclusions HDMFP, Der p 1 and Der p 2 are potent inducers of NO. Neither LPS nor the enzymatic activity of Der p 1 was responsible for NO production observed.

Nitric Oxide Production by Alveolar Macrophages in Response to House Dust Mite Fecal Pellets and the Mite Allergens, Der p 1 and Der p 2

BackgroundAllergens are frequently found within or attached to particulate material. For example, house dust mite fecal pellets (HDMFP) contain the major mite allergens, exposure to which have been implicated in the development of asthma. Although several studies have examined the ability of purified allergens to generate inflammatory responses, few studies have investigated whether HDMFP per se, are biologically active.ObjectiveOur objective was to examine the ability of whole HDMFP to stimulate nitric oxide (NO) release from alveolar macrophages.MethodsThe rat alveolar macrophage cell line, NR8383, was exposed to HDMFP, Der p 1, or Der p 2, and nitrite levels in the culture supernatants were measured with the Griess reagent. NO synthase mRNA expression was determined by RT-PCR.ResultsHDMFP stimulated the production of NO in a dose-dependent and time-dependent manner, with maximum NO levels measured after 48 hours of exposure. Inclusion of polymyxin B did not influence NO production, suggesting that LPS was not responsible for NO production. HDMFP-mediated NO release was down-modulated after treatment with NG-nitro-l-arginine methyl ester (L-NAME), dexamethasone, EDTA, and cysteine, but not heat treatment. Inducible nitric oxide synthase mRNA was observed 3 hours after HDMFP exposure, with maximum levels after 48 hours. Both purified Der p 1 and Der p 2 induced NO production, and inhibition of the cysteine protease activity of Der p 1 had little effect on NO production.ConclusionsHDMFP, Der p 1 and Der p 2 are potent inducers of NO. Neither LPS nor the enzymatic activity of Der p 1 was responsible for NO production observed.

House dust mite faecal pellets induce nitric oxide production in rat alveolar macrophages

House dust mite faecal pellets induce nitric oxide production in rat alveolar macrophages

The transmembrane protein occludin of epithelial tight junctions is a functional target for serine peptidases from faecal pellets of Dermatophagoides pteronyssinus.

There have been only a few studies of how allergens cross the airway epithelium to cause allergic sensitization. House dust mite fecal pellets (HDMFP) contain several proteolytic enzymes. Group 1 allergens are cysteine peptidases, whilst those of groups 3, 6 and 9 have catalytic sites indicative of enzymes that mechanistically behave as serine peptidases. We have previously shown that the group 1 allergen Der p 1 leads to cleavage of tight junctions (TJs), allowing allergen delivery to antigen presenting cells. In this study we determined whether HDMFP serine peptidases similarly compromise the airway epithelium by attacking TJs, desmosomes and adherens junctions. Experiments were performed in monolayers of MDCK, Calu-3 or 16HBE14o-epithelial cells. Cell junction morphology was examined by 2-photon molecular excitation microscopy and digital image analysis. Barrier function was measured as mannitol permeability. Cleavage of cell adhesion proteins was studied by immunoblotting and mass spectrometry. HDMFP serine peptidases led to a progressive cleavage of TJs and increased epithelial permeability. Desmosomal puncta became more concentrated. Cleavage of TJs involved proteolysis of the TJ proteins, occludin and ZO-1. This was associated with activation of intracellular proteolysis of ZO-1. In contrast to occludin, E-cadherin of adherens junctions was cleaved less extensively. Although Calu-3 and 16HBE14o-cells expressed tethered ligand receptors for serine peptidases, these were not responsible for transducing the changes in TJs. HDMFP serine peptidases cause cleavage of TJs. This study identifies a second general class of HDM peptidase capable of increasing epithelial permeability and thereby creating conditions that would favour transepithelial delivery of allergens.

Corticolous mites (Acari) as potential vectors of Cryphonectria parasitica (Murr.) barr hypovirulent strains

Specimens of four species of corticolous mites, Liebstadia humerata Sell. (Oribatida: Protobatidae), Scheloribates latipes (C. L. Koch) (Oribatida: Scheloribatidae), Thyreophagus corticalis (Mich.) (Acaridida: Acaridae), and Zygoribatula laubieri meridionalis Travé (Oribatida: Oribatulidae), were found in cankers, caused by Cryphonectria parasitica on chestnut trees, and were reared on laboratory cultures of the parasite. Monoxenic cultures were carried out using a hypovirulent (H) strain of the blight fungus. A group of mites was transferred from the H cultures to a met auxotrophic virulent (V) strain. Fecal pellets collected aseptically were used to inoculate agar plates. New C. parasitica cultures developed and white colonies with the morphological characters of the hypovirulent strain were obtained. Development of C. parasitica from mites indicated that the mycelial fragments were viable. The dsRNA presence in these cultures obtained from fecal pellets deposited by mites feeding from the blight agent mycelia was emphasized. Inoculation tests in the field confirmed that the white strains developed from the mite's fecal pellets were hypovirulent and suggested that these arthropods play a leading role in the natural spreading of hypovirulence in the chestnut stands.

Guanine and mite allergenicity in house dust

Guanine is the major nitrogenous waste product in arachnids. It may serve as an indicator for allergenic mite faecal pellets. The present study assesses the correlation between the mit allergenicity of different house dust (HD) samples and their guanine content. Guanine content in HD samples was evaluated either by the Acarex-Test or determined quantitatively, especially for in-vitro methods. Using intradermal tests in selectively sensitized Dermatophagoides pteronyssinus (Dpt) patients, we evaluated the mite allergenicity of eight extracts obtained from HD samples with varying guanine contents. The weal area appeared to be proportional to the HD samples' guanine content. A three-fold increase in skin reactivity was observed when the guanine content varied from 0.06% to more than 1%. Patients allergic to HD but not to Dpt had no significant reactions with HD extract prepared from a guanine-rich HD sample. For eighteen different HD samples coupled to paper discs, the percentage Dpt RAST binding values obtained with a Dpt-selectively sensitized patient serum pool was correlated with the guanine concentrations of HD samples (P less than 0.01). The potencies of different HD extracts obtained from HD samples that varied in guanine content were also clearly distinguished on histamine-release titration curves. House dust obtained from homes at high altitude or from hospitals was generally guanine free. The HD sample guanine contents in homes where twelve Dpt-sensitized patients experienced symptoms were significantly higher than in homes where these patients were symptom free. The guanine colour test, a quick and easy technique, represents an important new development in indoor environmental investigations. It makes it possible to demonstrate mite faecal exposure and can be used to monitor the effectiveness of mite allergen avoidance measures.