Critical roles for excretory-secretory cysteine proteases during tissue invasion of Paragonimus westermani newly excysted metacercariae

Abstract

SummaryParagonimus westermani is a trematode parasite, which causes pulmonary and/or extrapulmonary granulomatous disease in humans. Successful invasion of the host tissue is critical for the survival of this tissue-invasive parasite. The enzymatic hydrolysis of host proteins is clearly a prerequisite of this process. In this study, we have investigated the functional roles of the excretory-secretory cysteine proteases of P. westermani newly excysted metacercariae (PwNEM) in tissue invasion. The 27 and 28 kDa enzymes (PwMc27 and PwMc28) purified from PwNEM excretory-secretory products (ESP), preferentially degraded fibrillar proteins, but not globular proteins. PwMc28 significantly facilitated the invasion of PwNEM into mouse peritoneum, whereas a diffusible cysteine protease inhibitor, trans -epoxysuccinyl-L -leuciloamido-(4-guanidino) butane (E-64) inhibited this process dose-dependently. Two distinct isoforms of PwMc28 (PwMc28a and PwMc28b), which exhibited two amino acid differences in their mature domains, were identified by tandem mass spectrometry and sequence analysis. Both enzymes were localized at the tegument on the anterior border and on the oral sucker, which suggests excretion-secretion via exocytosis or via the excretory canal network. The mRNA transcripts of PwMc28a and b were expressed abundantly during the active invasion/migration through the host's tissues, suggesting their relevant function to tissue invasion/migration in the definitive host.

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

“…On the basis of the substrate specificity, the 27 kDa CP purified from the ESP shared similarity with sparganum cathepsin S [13] or Fasciola hepatica cathepsin L [14], whereas the 28 kDa CP had mammalian cathepsin B-like properties [15]. A recent report has shown that the proteolytic activity of the 27 kDa CP against a Z-FR-AMC substrate was higher than that of the 28 kDa CP, and that the 28 kDa, but not the 27 kDa, CP directly facilitated tissue penetration by the PwNEM [2]. These collective data strongly suggest that these 2 cysteine proteses secreted by PwNEM have a different role in the host immune functions during tissue invasion in vivo.…”

“…P. westermani newly excysted larvae (PwNEM) secrete excretory-secretory products (ESP) that are mainly composed of 2 cysteine proteases of 27 and 28 kDa size, which are required for excystment of the metacercariae [1], successful larval tissue invasion [2], and evasion of the host's immune system [3]. Moreover, recent studies have shown that proteases in the ESP secreted by PwNEM regulate IL-8 production and the life span of human eosinophils [4,5].…”

A Case of Incidentally Diagnosed Adrenal Paragonimiasis

“…In this case, although the exact cause is unknown, Paragonimus spp remained only in the abdominal cavity and right adrenal gland. There was no obvi- Recent studies suggest that enzymatic hydrolysis of host proteins by cysteine proteases is an essential step in host cell invasion and migration [17,18]. One hypothesis could be that there was some problem in this process which showed developmental stage-specific expression of the enzyme.…”

Identification and characterization of a cathepsin L-like cysteine protease from Taenia solium metacestode

“…The entire assay was carried out employing a Z-LR-AMC substrate. Kang et al, 2004;Lustigman et al, 2004;Dvorak et al, 2005;Na et al, 2006). However, only limited biochemical and immunological studies on the cysteine proteases of cestode parasites have been done.…”