Identification of Novel Allergenic Components from German Cockroach Fecal Extract by a Proteomic Approach

Abstract

Background: Cockroaches produce potent allergens, and cockroach feces are known to be especially rich in allergens. In this study, we analyze the allergenic components from cockroach feces and evaluate allergenicity of recombinant α-amylase identified from fecal extract. Methods: IgE-reactive proteins from German cockroach fecal extract were analyzed by proteomic analysis and immunoblotting. Recombinant α-amylase was produced and its allergenicity was evaluated by ELISA. Results: Analysis of German cockroach fecal extracts identified 12 IgE-reactive components. Most of these allergens were found to be digestive enzymes such as α-amylase, trypsin, chymotrypsin, metalloprotease, and midgut carboxypeptidase A, but the identity of 3 IgE-reactive proteins is still unknown. Glycinin-like proteins, which were likely derived from the cockroach diet, were also identified. German cockroach α-amylase shares the highest identity with pig α-amylase (55.8%), followed by mite group 4 allergens (Blo t 4, 50.4%; Der p 4, 49.8%; Eur m 4, 47.4%). In this study, recombinant α-amylase from German cockroach was expressed, and its allergenicity was examined by ELISA. Specific IgE against recombinant amylase was detected in 41.4% (12/29) of serum samples from German cockroach-sensitized subjects. Recombinant α-amylase was able to inhibit 55% of specific IgE to German cockroach whole-body extract. Conclusions: Amylase was found to be an important novel allergen in cockroach feces. It is hoped that recombinant α-amylase will be useful for further studies and clinical applications.

New Insights into Cockroach Allergens

“…Since reviewed in 2014 [5,59], molecular studies have unveiled new structural features of allergens in groups 1, 2 and 5, and two new groups (11 and 12) have been added to the list. In addition to these officially recognized cockroach allergens, other potential allergens have also been identified that need further study [60–63]. This section will describe the twelve official groups of cockroach allergens with emphasis on new studies performed in the last 5 years.…”

“…First, recombinant Bla g 11 inhibited 55% of specific IgE to German cockroach whole-body extract among patients in Korea [63]. Second, the prevalence of IgE reactivity to group 11 allergens is high for certain populations: 1) Bla g 11 was recognized by 41.4% (12/29) of German cockroach sensitized subjects in Korea [63], and 2) a large proportion of Chinese cockroach allergic patients recognized natural Per a 11 purified from midgut of cockroaches using immunoblots (83%; 39/47) and skin prick test (80%; 12/15) [111]. Finally, Bla g 11 was immunodominant regarding T cell responses in asthmatic subjects, together with Bla g 5 and Bla g 9 ●[106].…”

“…Although their presence in the gastrointestinal tract of cockroaches has been known for a long time, chitinases have only recently been recognized as cockroach allergens [111,112]. These enzymes hydrolyze the N-acetyl-D-glucosamine 1,4-β-linkages of chitin polymers and are essential for digestion of chitin [63,111]. Chitinases, together with trypsins (group 10) and α-amylases (group 11), are part of the major digestive enzymes in cockroach [57].…”

Current Status of Standardization of Inhalant Allergen Extracts in Korea

“…2, Table 1). Amylase was also identified as an important allergen in German cockroach fecal extract 20. An interesting finding of fecal extract analysis is the IgE reactivity of various digestive enzymes, such as α-amylase, trypsin, chymotrypsin, metalloprotease, and midgut carboxypeptidase A.…”

Every Cockroach Is Beautiful to Its Mother

“…In this issue of International Archives of Allergy and Immunology , Jeong and colleagues (14), from Korea, have used a proteomics approach to identify novel cockroach allergens in a B. germanica fecal extract. As it could be predicted, they have found that four of 12 IgE binding proteins were digestive enzymes including midgut carboxy peptidase A, chymotrypsin, astacin-like metalloprotease and trypsin.…”