The Challenge of the Sponge Suberites domuncula (Olivi, 1792) in the Presence of a Symbiotic Bacterium and a Pathogen Bacterium

Abstract

Sponges, which are in close contact with numerous bacteria in prey/predator, symbiotic and pathogenic relationships, must provide an appropriate response in such situations. This starts with a discriminating recognition of the partner either by a physical contact or through secreted molecules or both. We investigated the expression of the Toll-like receptor, Caspase 3/7, Tumor Necrosis Factor receptor-associated factor 6, Bcl-2 homology protein-2 and macrophage expressed genes of axenic sponge cells in the presence of a symbiotic bacterium (Endozoicomonas sp. Hex311), a pathogen bacterium (Pseudoalteromonas sp. 1A1), their exoproducts and lipopolysaccharides. The vast majority of answers are in line with what could be observed with the symbiotic bacterium. The pathogenic bacterium seems to profit from the eukaryotic cell: suppression of the production of the antibacterial compound, inhibition of the apoptosis caspase-dependent pathway, deregulation of bacterial recognition. This work contributes new scientific knowledge in the field of immunology and apoptosis in early branching metazoan harboring within its tissue and cells a large number of symbiotic bacteria.

Breaching the Bacterial Envelope: The Pivotal Role of Perforin-2 (MPEG1) Within Phagocytes

“…It is also not yet known if Perforin-2 can breach bacterial membranes by itself or if it requires the assistance of other host proteins. Our review and evaluation of the in vitro systems reported to date raises significant doubts that Perforin-2 dependent killing was actually observed with recombinant protein ( 27 , 29 – 31 , 33 , 34 , 38 , 39 , 43 ). Our first major concern is that some researchers opted to purify the MACPF domain in the absence of the P2 domain ( 29 , 31 , 43 ).…”

“…Nevertheless in recent years vertebrate studies have established that Perforin-2 has broad spectrum bactericidal activity that significantly limits pathogen proliferation and dissemination in vivo ( 15 , 19 , 26 , 52 – 54 , 57 , 72 , 90 ). There is also evidence to suggest that Perforin-2 functions similarly in invertebrates; although, such studies are hampered by the lack of animal and tractable cell culture models ( 27 , 28 , 30 , 31 , 33 , 38 , 39 ). The recent structural determinations of both mouse and human Perforin-2 polymers have further provided significant insight with regards to the mechanism(s) of pore formation ( 20 , 21 ).…”

“…For example, in S. domuncula expression of Mpeg1 is dampened by the bacterial sponge pathogen Pseudoalteromonas sp., but not the commensal bacterium Endozoicomonas sp. ; species were indeterminate ( 38 ). This differential effect is suggestive of a pathogenic countermeasure deployed to defeat Perforin-2.…”

Global patterns in symbiont selection and transmission strategies in sponges

“…Hostmicrobiota interactions are based on the exchange of information, that comes from the microbial signal -host receptor interactions. This recognition lies in the host innate immune system, which plays a crucial role in animal-microbe crosstalk (Schmittmann et al, 2020;Ie Pennec and Gardères, 2019;Dierking and Pita, 2020). The host innate immune system includes a complex repertoire of immune receptors, so-called pattern recognition receptors (PRRs), that recognize the microbe associated molecular patterns (MAMPs) present in prokaryotes but absent in eukaryotes (Medzhitov and Janeway, 2002;Koropatnick et al, 2004).…”

Transmission of the sponge microbiome: moving towards a unified model

“…2A. Some studies have also described receptor molecules in sponges, including pathogen‐recognition receptors (PRRs) and pathogen‐associated molecular patterns (PAMPs), which are well‐conserved molecular structures expressed by various pathogens (virus, bacteria, fungi, protozoans, helminths) (Hentschel et al ., 2012; Yuen et al ., 2014; Di Lorenzo, 2017; Pita et al ., 2018a; Le Pennec and Gardères, 2019).…”