A Shift from Cellular to Humoral Responses Contributes to Innate Immune Memory in the Vector Snail Biomphalaria glabrata

TLDR

Invertebrate antiparasitic responses can be sustainably primed, a phenomenon known as immune priming or innate immune memory, but it has largely been described only phenomenologically. The study aims to demonstrate immune priming in Biomphalaria glabrata and to uncover its underlying mechanisms through rigorous functional and molecular testing. The authors performed molecular characterization of the shift from cellular encapsulation to humoral biomphalysin response in the Biomphalaria/Schistosoma system to reconcile mechanisms with observed phenomena. They found that innate memory in B.

Abstract

Discoveries made over the past ten years have provided evidence that invertebrate antiparasitic responses may be primed in a sustainable manner, leading to the failure of a secondary encounter with the same pathogen. This phenomenon called "immune priming" or "innate immune memory" was mainly phenomenological. The demonstration of this process remains to be obtained and the underlying mechanisms remain to be discovered and exhaustively tested with rigorous functional and molecular methods, to eliminate all alternative explanations. In order to achieve this ambitious aim, the present study focuses on the Lophotrochozoan snail, Biomphalaria glabrata, in which innate immune memory was recently reported. We provide herein the first evidence that a shift from a cellular immune response (encapsulation) to a humoral immune response (biomphalysin) occurs during the development of innate memory. The molecular characterisation of this process in Biomphalaria/Schistosoma system was undertaken to reconcile mechanisms with phenomena, opening the way to a better comprehension of innate immune memory in invertebrates. This prompted us to revisit the artificial dichotomy between innate and memory immunity in invertebrate systems.