A bloody interaction: plasma proteomics reveals gilthead sea bream (Sparus aurata) impairment caused by Sparicotyle chrysophrii

Abstract

Background Sparicotylosis is an enzootic parasitic disease that is well established across the Mediterranean Sea. It is caused by the polyopisthocotylean monogenean Sparicotyle chrysophrii and affects the gills of gilthead sea bream (GSB; Sparus aurata). Current disease management, mitigation and treatment strategies are limited against sparicotylosis. To successfully develop more efficient therapeutic strategies against this disease, understanding which molecular mechanisms and metabolic pathways are altered in the host is critical. This study aims to elucidate how S. chrysophrii infection modulates the plasma proteome of GSB and to identify the main altered biological processes involved. Methods Experimental infections were conducted in a recirculating aquaculture system (RAS) in which naïve recipient GSB ([R]; 70 g; n = 50) were exposed to effluent water from S. chrysophrii-infected GSB (98 g; n = 50). An additional tank containing unexposed naïve fish (control [C]; 70 g; n = 50) was maintained in parallel, but with the open water flow disconnected from the RAS. Haematological and infection parameters from sampled C and R fish were recorded for 10 weeks. Plasma samples from R fish were categorised into three different groups according to their infection intensity, which was based on the number of worms fish−1: low (L: 1–50), medium (51–100) and high (H: > 100). Five plasma samples from each category and five C samples were selected and subjected to a SWATH-MS proteome analysis. Additional assays on haemoglobin, cholesterol and the lytic activity of the alternative complement pathway were performed to validate the proteome analysis findings. Results The discriminant analysis of plasma protein abundance revealed a clear separation into three groups (H, M/L and C). A pathway analysis was performed with the differentially quantified proteins, indicating that the parasitic infection mainly affected pathways related to haemostasis, the immune system and lipid metabolism and transport. Twenty-two proteins were significantly correlated with infection intensity, highlighting the importance of apolipoproteins, globins and complement component 3. Validation assays of blood and plasma (haemoglobin, cholesterol and lytic activity of alternative complement pathway) confirmed these correlations. Conclusions Sparicotylosis profoundly alters the haemostasis, the innate immune system and the lipid metabolism and transport in GSB. This study gives a crucial global overview of the pathogenesis of sparicotylosis and highlights new targets for further research. Graphical Abstract

An inside out journey: biogenesis, ultrastructure and proteomic characterisation of the ectoparasitic flatworm Sparicotyle chrysophrii extracellular vesicles

“…Gene Ontology analyses from the purified EVs indicated biological processes related to blood (negative regulation of coagulation, iron ion transport, haemocyte migration and intracellular iron ion homeostasis; Fig. 4 A), consistent with the negative haemostatic impact [ 68 , 69 ] and catalytic process (regulation of catalytic activity and proteolysis) observed in infected S. aurata . Molecular functions revealed ferric and metal ion binding, ferroxidase activity, glutathione transferase and enzymatic activities related to oxidoreductase, transferase, hydrolase-peptidase, lyase, isomerase, ligase and translocase enzymes (Fig.…”

“…The liver fluke, F. hepatica , exhibits an extracellular digestion phase in its gut lumen [ 67 ], and a similar process is presumed in Eudiplozoon nipponicum (Goto, 1891) (Polyopisthocotyla: Diplozoidae) [ 10 ]. However, Riera-Ferrer et al [ 68 ] suggested that S. chrysophrii induces an intravascular haemolysis in its host, prior to ingesting the resulting blood meal. Thus, ESPs and EV-originating peptidases and peptidase inhibitors might have a crucial role in this parasite’s feeding strategies.…”

Mucosal affairs: glycosylation and expression changes of gill goblet cells and mucins in a fish–polyopisthocotylidan interaction

“…The main clinical sign during sparicotylosis is anemia, which is caused by the hematophagous nature of a parasite ( 32 , 39 , 50 ). Furthermore, the parasite’s attaching mechanism to the gill filament through specialized clamps in its opisthaptor region ( 51 ) inflicts evident histopathological lesions such as lamellar synechiae and clubbing, resulting in disruption of the epithelium and marginal blood vessels ( 50 ).…”

“…The high stocking densities, the lack of fallowing strategies, and the enzootic locations of the off-shore cage farms are favoring parasite outbreaks and transmission. The growing concern in regard to the production losses has directed recent research efforts toward studies on the parasites’ biology ( 24 – 28 ), the host response ( 29 – 32 ), and the search for treatments ( 33 – 38 ). However, a closer look at the modulation of the mucous secretion and the goblet cells in the gills of gilthead seabream during the course of this parasitosis has not been thoroughly taken.…”

Monogenean Sparicotyle chrysophrii: The major pathogen of the Mediterranean gilthead seabream aquaculture

“…Sparicotylosis clinical progress, observed through the increase in infection levels reflects in the host serology. In total 22 proteins belonging to apolipoproteins, globins, and complement c3 were found significantly correlated with the infection intensity in plasma samples from fish undergoing low (1–50 monogeneans/fish), medium (51–100), and high (>100) infection 118 . The proteomics of host plasma showed perturbation of haemostasis, immunity, and lipid metabolism, and transport pathways, supporting the systemic response to the infection.…”