查看更多>>摘要：One of the major evolutionarily conserved pathways in innate immunity of invertebrates is the toll-like receptor (TLR) pathway. However, little is known of the TLR protein family in gastropod molluscs despite their role in the transmission of human diseases, especially the common lymnaeid freshwater snail species Radix auricularia and Lymnaea stagnalis, key intermediate hosts of zoonotic trematodes. Using comparative genomics and gene prediction approaches utilising the freshwater snail Biomphalaria glabrata genome as a reference ten putative TLR proteins were identified in both R. auricularia and L. stagnalis. Phylogenetic analyses revealed that unlike other molluscs the lymnaeid species also possessed class 1 TLRs, previously thought to be unique to B. glabrata. Gene duplication events were also seen across the TLR classes in the lymnaeids with several of the genes appearing to exist as potential tandem elements in R. auricularia. Each predicted TLR was shown to possess the typical the leucine-rich repeat extracellular and TIR intracellular domains and both single cysteine clusters and multiple cysteine clusters TLRs were identified in both lymnaeid species. Principle component analyses of 3D models of the predicted TLRs showed that class 1 and 5 proteins did not cluster based on similarity of structure, suggested to be potential adaptation to a range of pathogens. This study provides the first detailed account of TLRs in lymnaeids and affords a platform for further research into the role of these proteins into susceptibility and compatibility of these snails with trematodes and their role in transmission.
查看更多>>摘要：Arginine metabolism pathway enzymes and products are important modulators of several physiological processes in animals, including immune response. Although some components of the arginine metabolic pathway have been reported in penaeid shrimps, no systematic study has explored all the key pathway enzymes involved in shrimp antimicrobial response. Here, we explored the role of the three key arginine metabolism enzymes (nitricoxide synthase (NOS), arginase (ARG), agmatinase (AGM)) in Penaeus vannamei antimicrobial immunity. First, P. vannamei homologs of ARG and AGM (PvARG and PvAGM) were cloned and found to be evolutionally conserved with invertebrate counterparts. Transcript levels of PvARG, PvAGM, and PvNOS were ubiquitously expressed in healthy shrimp tissues and induced in hemocytes and hepatopancreas upon challenge with Gramnegative (Vibrio parahaemolyticus) and Gram-positive (Streptoccocus iniae) bacteria, suggesting their involvement in shrimp antimicrobial immune response. Besides, RNA interference knockdown and enzyme activity assay revealed an antagonistic relationship between PvARG/PvAGM and PvNOS, while this relationship was broken upon pathogen stimulation. Interestingly, knockdown of PvNOS increased Vibrio abundance in shrimp hemolymph, whereas knockdown of PvAGR reduced Vibrio abundance. Taken together, our present data shows that homologs of the key arginine metabolism pathway enzymes in penaeid shrimp (PvARG, PvAGM, and PvNOS) work synergistically and/or antagonistically to modulate antibacterial immune response.
查看更多>>摘要：CD5 is a type I transmembrane glycoprotein acting as a pleiotropic functional receptor in the mammalian immune response system, mainly presents on the surface of cells associated with the immune system, and is essential for the classification of B cells. In this study, we identify a CD5 homologue in Nile tilapia (Oreochromis niloticus). The open reading frame of OnCD5 is 507 bp, encoding 168 amino acids. The deduced amino acid sequence contains a signal peptide region, a transmembrane region and a conserved portion of the cytoplasmic region. Expression analysis indicates that the OnCD5 exhibits constitutive expression in the tested tissues, with the highest expression in thymus. Analysis of the OnCD5 transcription in the classified IgM(+) and IgM(-) lym phocytesfrom anterior kidney, spleen and peripheral blood, and IgMlo and IgMhi lymphocytes from peripheral blood, indicates that the OnCD5 is highly expressed in the IgM (+) lymphocytes, especially in the IgMhi B lymphocytes. Furthermore, the OnCD5 expression is up-regulated significantly in anterior kidney and spleen following challenges of Aeromonas hydrophila and Streptococcus agalactiae in vivo and in vitro, likewise in IgM(+) B lymphocytes sorted from peripheral blood upon stimulation with LPS. Further, the recombinant OnCD5 protein has the bacteria-binding activity. Taken together, these results reveal that OnCD5 participates in host's defense during pathogen infection, and may play an important role in tilapia B cells.
查看更多>>摘要：Invertebrates are the protagonists of a recent paradigm shift because they now show that vertebrates are not the only group with immune memory. This review discusses the concept of immune priming, its characteristics, and differences with trained immunity and immune enhancement. We include an update of the current status of immune priming within generations in different groups of invertebrates which now include work in 5 Phyla: Ctenophora, Cnidaria, Mollusca, Nematoda, and Arthropoda. Clearly, few Phyla have been studied. We also resume and discuss the effector mechanism related to immune memory, including integrating viral elements into the genome, endoreplication, and epigenetics. The roles of other elements are incorporated, such as hemocytes, immune pathways, and metabolisms. We conclude that taking care of the experimental procedure will discern if results provide or do not support the invertebrates' immune memory and that regarding mechanisms, indeed, there are no studies on the immune memory mechanisms, this is how specificity is reached, and how and where the immune memory is stored and how is recall upon subsequent encounters. Finally, we discuss the possibility of having more than one mechanism working in different groups of invertebrates depending on the environmental conditions.
查看更多>>摘要：The myeloid differentiation factor 2 (MD-2)-related lipid recognition (ML) domain is present in MD-2, MD-1, GM2-activator protein (GM2A) and Niemann-Pick disease type C2 (NPC2). ML proteins function in antibacterial signal transduction and lipid metabolism in vertebrates, but the mechanism in invertebrates is unknown. In this study, we found that ML proteins were involved in bacterial resistance in Chinese mitten crab (Eriocheir sinensis). One member, EsML3, a soluble, bacterial-induced pattern recognition protein was upregulated in hemocytes following bacterial challenge. Recombinant EsML3 bound to Gram-negative bacteria (Vibrio parahaemolyticus) and Gram-positive bacteria (Staphylococcus aureus) by interaction with peptidoglycan, lipopolysaccharide. EsML3 showed no direct bacteriostatic or bacteriocidal activity. Pre-incubating bacteria with rEsML3 significantly promoted in vivo bacterial clearance. EsML3 also promoted phagocytic activity and plays a role against bacterial infection. In summary, EsML3 mediates cellular immune responses by recognising invasive microorganisms, promoting bacterial clearance and phagocytosis against bacterial infection in crab.
NSTL
Elsevier