The pervasive effects of recombinant Fasciola gigantica Ras-related protein Rab10 on the functions of goat peripheral blood mononuclear cells

Abstract

BackgroundFasciola gigantica-induced immunomodulation is a major hurdle faced by the host for controlling infection. Here, we elucidated the role of F. gigantica Ras-related protein Rab10 (FgRab10) in the modulation of key functions of peripheral blood mononuclear cells (PBMCs) of goats.MethodsWe cloned and expressed recombinant FgRab10 (rFgRab10) protein and examined its effects on several functions of goat PBMCs. Protein interactors of rFgRab10 were predicted in silico by querying the databases Intact, String, BioPlex and BioGrid. In addition, a total energy analysis of each of the identified interactions was also conducted. Gene Ontology (GO) enrichment analysis was carried out using FuncAssociate 3.0.ResultsThe FgRab10 gene (618 bp), encodes 205-amino-acid residues with a molecular mass of ~23 kDa, had complete nucleotide sequence homology with F. hepatica Ras family protein gene (PIS87503.1). The rFgRab10 protein specifically cross-reacted with anti-Fasciola antibodies as shown by Western blot and immunofluorescence analysis. This protein exhibited multiple effects on goat PBMCs, including increased production of cytokines [interleukin-2 (IL-2), IL-4, IL-10, transforming growth factor beta (TGF-β) and interferon gamma (IFN-γ)] and total nitric oxide (NO), enhancing apoptosis and migration of PBMCs, and promoting the phagocytic ability of monocytes. However, it significantly inhibited cell proliferation. Homology modelling revealed 63% identity between rFgRab10 and human Rab10 protein (Uniprot ID: P61026). Protein interaction network analysis revealed more stabilizing interactions between Rab proteins geranylgeranyltransferase component A 1 (CHM) and Rab proteins geranylgeranyltransferase component A 2 (CHML) and rFgRab10 protein. Gene Ontology analysis identified RabGTPase mediated signaling as the most represented pathway.ConclusionsrFgRab10 protein exerts profound influences on various functions of goat PBMCs. This finding may help explain why F. gigantica is capable of provoking recognition by host immune cells, less capable of destroying this successful parasite.Electronic supplementary materialThe online version of this article (10.1186/s13071-018-3148-2) contains supplementary material, which is available to authorized users.

Modulation of the Functions of Goat Peripheral Blood Mononuclear Cells by Fasciola gigantica Thioredoxin Peroxidase In Vitro

“…F. gigantica discharges many ES molecules that seem to play roles in the induction of this type of immune response. F. gigantica -derived ESPs, identified in the present study (rFgTPx) and in previous studies (rFg14-3-3e [ 20 ] and rFgRab10 [ 21 ]), have induced Th1 (IFN-γ, IL-2) and Th2 (IL-4, IL-10, TGF-β) cytokines, except IL-4 and IFN-γ, whose levels were low in response to rFg14-3-3e. Cytokines are produced by a variety of immune cells and play various roles in protecting the host and maintaining tissue homeostasis [ 28 , 29 ].…”

“…It is readily known that other F. gigantica effector proteins, rFg14-3-3e [ 20 ] and rFgRab10 [ 21 ], alter the phagocytic function of monocytes by decreasing or increasing their phagocytic capacities, respectively, or simply kill PBMCs by inducing apoptosis. By reducing monocyte phagocytosis, rFgTPx would augment the action of rFg14-3-3e [ 20 ] and antagonize the action of rFgRab10 [ 21 ] with regard to the phagocytic capacity of monocytes. By promoting apoptosis at 10–40 μg/mL concentrations, rFgTPx seems to potentiate the action of both rFg14-3-3e and rFgRab10 proteins.…”

“…Eight local goats (3 to 6 months old) were used in this study. As previously described, goats were treated with triclabendazole to rule out Fasciola infection and kept under hygienic F. gigantica -free conditions [ 21 ]. All goats were fed with commercial hay and corn, and allowed to drink water ad libitum.…”

“…Western blot analysis was performed as previously described [ 21 ]. Briefly, the purified rFgTPx was loaded onto 12% SDS-PAGE gel, then transferred to Hybond-C extra nitrocellulose membranes (Amersham Biosciences, United Kingdom) and blocked with 5% bovine serum albumin (BSA) in TBS–Tween 20 (TBST) for 1 h at 37 °C.…”

“…Excretory and secretory products (ESPs), containing many active molecules, have been produced by these parasites under in vitro and in vivo conditions [ 17 ]. Previous reports showed that different molecules of ESPs from F. gigantica (FgESPs) can cause various immune responses—for example, some molecules can simulate host defense against parasites, while other have exerted the opposite effect [ 16 , 18 , 19 , 20 , 21 ]. Of particular importance to their survival is the ability of liver flukes to employ an anti–oxidant, redox-based system that protects the liver flukes against the reactive oxygen and nitrogen species produced by host immune cells and endogenous cellular metabolism [ 22 ].…”