Inflammatory potential of particles from the Echinococcus granulosus
laminated layer
Abstract
Cystic echinococcosis is caused by the tissue-dwelling larva (hydatid)
of Echinococcus granulosus sensu lato. A salient feature is this
larva is being protected by the acellular laminated layer (LL), made up
of mucins and calcium inositol hexakisphosphate (Ins P
6). As the parasite grows, the LL sheds abundant
particles that can accumulate in the parasite’s vicinity. Although
foreign particles accumulating in tissues usually cause inflammation,
the LL displays adaptations for minimising various host responses, and
in vivo evidence of inflammation induced by LL particles is
essentially lacking. In this work, we show that LL particles injected
i.p. at a dose of 225 μg dry mass per mouse cause infiltration of
eosinophils, neutrophils and monocytes/macrophages as well as
disappearance of resident (large peritoneal) macrophages. The calcium
Ins P 6 component was dispensable for these
responses. Oxidation of the mucin carbohydrates caused decreased
recruitment of neutrophils but the carbohydrate-oxidized particles
caused cell influx nonetheless. The control of local granulomatous
inflammation is key for survival of this larva. Therefore, our results
suggest that E. granulosus must deploy mechanisms to avoid
excessive local build-up of LL particles (such as targeting particles to
liver Kupffer cells; Infect Immun 91:e0003123) and/or to
condition the recruited cells towards immune-regulatory phenotypes.