Cockroach allergens identified: Personalised profiling of allergic people on the horizon

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  • Published: Nov 22, 2010
  • Author: Steve Down
  • Channels: Proteomics & Genomics
thumbnail image: Cockroach allergens identified: Personalised profiling of allergic people on the horizon

The German cockroach: pest and health hazard

The cockroach is one of the most despised creatures around the world, especially the Western world, due to its invasive nature. It infests buildings, preferring warm and damp habitats, and is often to be found in kitchens, restaurants and food storage areas but it will set up home anywhere where there is a plentiful supply of food.

For the cockroach, food means virtually anything of plant or animal origin, even human cast offs like hair and fingernails. It is this versatility, coupled with a tolerance for almost any environment, which has enabled this insect to flourish all over the planet. It has even been found at the North and South Poles. This ancient creature, about 350 million years old, has faced many challenges and has been able to adapt to poisons and nuclear radiation.

Perceived as dirty creatures, cockroaches are much more than that. They are a serious health hazard to many people due to a series of allergens which they produce, causing perennial rhinitis and asthma. The allergens are released in faeces, secretions and cast-off skin into house dust, from where they can spread into the air to cause problems.

In recent US and Taiwanese studies, more than one third of asthmatic children tested were allergic to cockroaches, especially the German cockroach (Blattella germanica). Yet, despite these figures, little is known about the particular compounds that are responsible for the allergic reactions. Previous studies have provided limited and inconsistent results.


Cockroach allergens: a proteomic approach to ten new members

A new -omics technique, allergenomics, was developed a few years ago to screen and identify new allergens. It has now been adopted by Lu-Ping Chow and colleagues from the National Taiwan University, Taipei and the Veterans General Hospital, Taiwan, to mine novel allergens from the German cockroach.

Proteins were extracted from cockroach whole bodies and separated by 1D or 2D gel electrophoresis. They were transferred to PVDF membranes for immunoblotting using individual or pooled serum from cockroach-sensitive subjects to compare with the immunoblots from non-allergic healthy controls.

More than 20 protein bands sensitive to immunoglobulin E were detected, ranging from small to large (14-97 kDa). Five of these proteins were strongly reactive and were recognised by sera from many of the allergic patients.

The proteins were analysed by N-terminal sequencing and by tryptic digestion followed by tandem mass spectrometry. Together they identified 3 known cockroach allergens and 10 new allergens, including enolase, arginine kinase, fructose 1,6-bisphosphate aldolase and triosephosphate isomerase.

Searches against specialised allergen databases revealed that homologues of 6 proteins, aldolase, arginine kinase, enolase, heat shock protein 70, triosephosphate isomerase and vitellogenin, had been reported previously to be allergens in other species, including various fungi, shrimp and mites. However, this subset had never been reported as allergens in the German cockroach.


Allergic patients: a personalised approach to diagnosis and prevention

The research team used their findings to set up an allergen panel to test the sera of 32 allergic patients. Although a significant proportion of patients reacted to particular allergens, especially Bla g 2 and vitellogenin, the allergic profiles of each patient were notably different.

This variable reactivity to individual allergens suggests that the usual way of testing patient sensitivity, using crude extracts, could be refined to a component-resolved diagnosis which will lead to personalised reactivity profiles. Chow observed that immunoreactivity testing with multiple allergens can be accomplished using small amounts of serum in a few minutes, so it would not be a difficult task to establish a series of German cockroach allergy subtypes.

Such an approach would encourage a personalised medical approach to allergy prevention and therapy, based on the results for each patient, hopefully producing better and more effective treatment.



The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

 
 
 
A comprehensive screening procedure has identified ten new allergenic proteins from the German cockroach and opens up the possibility of personalised profiling of individuals who suffer from cockroach allergies

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