Abstract
Excretory/secretory (ES) compounds isolated from third-stage larvae of the anisakid nematode Contracaecum osculatum parasitizing liver of Baltic cod were investigated for effects on immune gene expression in a zebrafish LPS-induced inflammation model. ES products containing a series of proteins, of which some had enzymatic activity, were injected solely or with LPS. ES proteins alone induced up-regulation of a number of immune-related genes, but generally to a lower degree compared to LPS. When co-injected with LPS, the worm products exacerbated merely expression of five genes affecting Th1, Th2, Th17 and innate responses compared to the LPS-injected group. However, the level of overexpression decreased in an inverse dose-dependent manner. The immune regulating action of C. osculatum ES products is interpreted as an important evolutionary ability of larval parasites in the transport host which makes it less susceptible to host immune responses whereby the probability of reaching the final host is increased.
Highlights
Parasitic helminths produce a series of excretory/secretory (ES) compounds which have been suggested to play an important role in parasite-host interactions [1]
Silver staining after SDS-PAGE revealed a series of protein bands with molecular weights (MW) ranging from 7 kDa to 375 kDa
The applied techniques for studying expression of both innate and adaptive immune genes in zebrafish were recently developed [23, 31] and we demonstrated that ES products from C. osculatum activate most immune genes in a dose-dependent manner, but generally at a markedly lower level compared to LPS
Summary
Parasitic helminths produce a series of excretory/secretory (ES) compounds which have been suggested to play an important role in parasite-host interactions [1] In nematodes this complex of molecules originates from different organs of the parasite (oesophagus, ventricle, intestine, glands) and comprises various enzymes with different functions in the host including penetration and migration in the host tissues, alteration of host physiology, and immunomodulation with the purpose of favouring parasite survival [1, 2]. Enzymes such as acetylcholinesterase (AChE), glutathione-S-transferase (GST), and superoxide dismutase (SOD) secreted by the hookworm Necator americanus act as anti-inflammatory molecules creating a shielded pathway in order to protect the worm from immune reactions [3]. The filarial nematode Wuchereria bancrofti produces AChE in the human host circulation which degrades
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