A 27 kDa Cysteine Protease Secreted by Newly Excysted Paragonimus westermani Metacercariae Induces Superoxide Anion Production and Degranulation of Human Eosinophils

Eosinophil degranulation plays a crucial role in tissue inflammatory reactions associated with helminth parasitic nfections and allergic diseases. Paragonimus westermani, a lung fluke causing human paragonimiasis, secretes a large amount of cysteine proteases, which are involved in nutrient uptake, tissue invasion, and modulation of hos's immune responses. There is, however, limited information about the response of eosinophils to direct stimulation by cysteine proteases (CP) secreted by P. westermani. In the present study, we tested whether degranulation and superoxide production from human eosinophils can be induced by stimulation of the 2 CP (27 kDa and 28 kDa) purified from excretory-secretory products (ESP) of P. westermani newly excysted metacercariae (PwNEM). A large quantity of eosinophil-derived neurotoxin (EDN) was detected in the culture supernatant when human eosinophils isolated from the peripheral blood were incubated with the purified 27 kDa CP. Furthermore, the 27 kDa CP induced superoxide anion production by eosinophils in time- and dose-dependent manners. In contrast, the purified 28 kDa CP did not induce superoxide production and degranulation. These findings suggest that the 27 kDa CP secreted by PwNEM induces superoxide production and degranulation of human eosinophils, which may be involved in eosinophil-mediated tissue inflammatory responses during the larval migration in human paragonimiasis.

Degranulation of human eosinophils induced by Paragonimus westermani-secreted protease

Eosinophil degranulation is considered to be a key effector function for the killing of helminthic worms and tissue inflammation at worm-infected lesion sites. However, relatively little data are available with regard to eosinophil response after stimulation with worm-secreted products which contain a large quantity of cysteine proteases. In this study, we attempted to determine whether the degranulation of human eosinophils could be induced by the direct stimulation of the excretory-secretory products (ESP) of Paragonimus westermani, which causes pulmonary paragonimiasis in human beings. Incubation of eosinophils for 3 hr with Paragonimus-secreted products resulted in marked degranulation, as evidenced by the release of eosinophil-derived neurotoxin (EDN) in the culture supernatants. Moreover, superoxide anion was produced by eosinophils after stimulation of the ESP. The ESP-induced EDN release was found to be significantly inhibited when the ESP was pretreated with protease inhibitor cocktail or the cysteine protease inhibitor, E-64. These findings suggest that human eosinophils become degranulated in response to P. westermani-secreted proteases, which may contribute to in vivo tissue inflammation around the worms.

Activation of Eosinophils with Airborne Fungi / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Allergic fungal sinusitis is characterized by allergic mucin which includes eosinophils and fungal hyphae. But we don't know why eosinophils are accumulated at the nasal secretion and activated, so authors tried to explain the pathophysiologic function of eosinophils by directly stimulating eosinophils with fungal antigens. SUBJECTS AND METHOD: Eosinophils were isolated from healthy volunteers and stimulated with extracts from 5 common fungal species (Alternaria, Aspergillus, Candida, Cladosporium, and Penicillium). Superoxide production and eosinophil derived neurotoxin (EDN) were measured to determine whether fungi activated eosinophils. An inhibition study was done using serine and cystein protease inhibitors. RESULTS: When cultured with fungal antigens, eosinophils produced superoxide by Alternaria and Cladosporium but only Alternaria induced EDN production. Serine protease inhibitors (PMSF, Pefabloc?) and heat treatment of fungi significantly inhibited the activation of eosinophils but the cystein protease inhibitor (E-64) wasn't inhibited. CONCLUSION: Eosinophils are directly activated by Alternaria and their activity was inhibited by serine protease inhibitors. In AFS, fungal serine proteases may activate eosinophils which play important roles in the pathogenesis of AFS, resulting in the destruction of fungi and respiratory epithelial cells.

Role of IL-5 and eotaxin in airway eosinophilic inflammation / 천식및알레르기

BACKGROUND: IL-5 and eotaxin are the most important cytokines/chemokines responsible for regulating eosinophil locomotion. OBJECTIVE: We investigated the role of IL-5 and eotaxin in airway eosinophilic inflammation in patients with chronic cough by analyzing sputum from patients. METHODS: Thirty-one patients who had chronic cough and seven normal control subjects were enrolled. Patients were divided into two groups, asthma group (n=15) and non-asthma group (n=16). Sputum was induced by inhalation of hypertonic saline. Total cell counts and differentials were determined. The levels of IL-5 and eotaxin were measured by ELISA, and the levels of EDN and MBP were measured by RIA. RESULTS: Patients in the asthma group showed higher percentage of eosinophils and higher levels of EDN and IL-5 (P<.001, P<.05 and P<.05, respectively) compared to subjects in the control group and higher % eosinophils, higher levels of EDN and MBP (P<.001, P<.05 and P<.05, respectively) compared to subjects in the control group. Non-asthma group patients also showed higher percentage of eosinophils and increased IL-5 levels (P<.05 and P<.05, respectively) compared to the control group. The eotaxin level correlated positively with percentage of eosinophils (Rs = 0.60, P<.001), the EDN (Rs = 0.59, P<.001) and MBP (Rs = 0.73, P<.01) levels, and correlated inversely with FEV1 % pred. (Rs = -0.71, P<.01). Unexpectedly, the IL-5 levels did not correlate significantly with any of sputum eosinophil indices or FEV1 % pred. CONCLUSION: Good correlation of eotaxin with sputum eosinophil indices or pulmonary function and no correlation of IL-5 with them suggest that eotaxin may play a more important role in the specific recruitment and degranulation of airway eosinophils, although both IL-5 and eotaxin are involved in local eosinophilic inflammation.