Expression of Perforin Gene for Early Development of Nephrons in Olive Flounder (Paralichthys olivaceus)

Regulation and distribution of European sea bass perforins point to their role in the adaptive cytotoxic response against NNV

Cell-mediated cytotoxicity is a complex immune mechanism that involves the release of several killing molecules, being perforin (PRF) one of the most important effector players. Perforin is synthesized by T lymphocytes and natural killer cells in mammals and responsible for the formation of pores on the target cell membrane during the killing process. Although perforin has been extensively studied in higher vertebrates, this knowledge is very limited in fish. Therefore, in this study we have identified four prf genes in European sea bass (Dicentrarchus labrax) and evaluated their mRNA levels. All sea bass prf genes showed the typical and conserved domains of its human orthologue and were closely clustered by the phylogenetic analysis. In addition, all genes showed constitutive and ubiquitous tissular expression, being prf1.9 gene the most highly expressed in immune tissues. Subsequently, in vitro stimulation of head-kidney (HK) cells with phytohemagglutinin, a T-cell activator, showed an increase of all prf gene levels, except for prf1.3 gene. European sea bass HK cells increased the transcription of prf1.2 and prf1.9 during the innate cell-mediated cytotoxic activity against xenogeneic target cells. In addition, sea bass infected with nodavirus (NNV) showed a similar expression pattern of all prf in HK and brain at 15 days post-infection, except for prf1.3 gene and in the gonad. Finally, the use of a polyclonal antibody against PRF1.9 showed an increase of positive cells in HK, brain and gonad from NNV-infected fish. Taken together, the data seem to indicate that all prf genes, except prf1.3, appear to be involved in the European sea bass immunity, and probably in the cell-mediated cytotoxic response, with PRF1.9 playing the most important role against nodavirus. The involvement of the PRFs and the CMC activity in the vertical transmission success of the virus is also discussed.

Regulation of Il-2 on the expression of granzyme B- and perforin-like genes and its functional implication in grass carp peripheral blood neutrophils

Granzyme (Gzm) B and perforin, both as cytotoxic proteins, can collaborate to induce the death of target cells as well as the microbes. They were originally discovered in cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells and confer the cytotoxic activities of these cells. In the present study, the coding sequences of a granzyme b-like (gcgzmbl) and a perforin-like (gcprfl) genes were cloned from grass carp (Ctenopharyngodon idellus) and their specific antibodies were subsequently prepared and validated. The mRNA and protein expression of these two cytotoxic proteins in grass carp peripheral blood neutrophils was demonstrated by quantitative PCR (qPCR) and immunofluorescence staining, respectively. In the same cell model, expression of gcGzmbl and gcPrfl was stimulated by grass carp interleukin (Il)-2 in a dose- and time-dependent manners and Erk, NF-κB and Stat5 pathways were found to be involved in the regulation of Il-2 on the genes' expression. Additionally, glycolysis was proved to play a role in the stimulation of Il-2 on gcGzmbl and gcPrfl expression in peripheral blood neutrophils. As combating the invading microorganisms is one of the main functions of neutrophils, the roles of gcGzmbl and gcPrfl in the anti-bacterial activities of grass carp peripheral blood neutrophils were explored. Results showed that immunoneutralization of gcGzmbl or gcPrfl significantly attenuated the antimicrobial abilities of the neutrophils enhanced by Il-2. These findings shed a light on the expression, regulation and functions of granzyme B- and perforin-like proteins in fish peripheral blood neutrophils and enrich the understanding of Il-2 function in fish innate immunity.

Summary and comparison of the perforin in teleosts and mammals: A review

Perforin, a pore-forming glycoprotein, has been demonstrated to play key roles in clearing virus-infected cells and tumour cells due to its ability of forming 'pores' on the cell membranes. Additionally, perforin is also found to be associated with human diseases such as tumours, virus infections, immune rejection and some autoimmune diseases. Until now, plenty of perforin genes have been identified in vertebrates, especially the mammals and teleost fish. Conversely, vertebrate homologue of perforin gene was not identified in the invertebrates. Although recently there have been several reviews focusing on perforin and granzymes in mammals, no one highlighted the current advances of perforin in the other vertebrates. Here, in addition to mammalian perforin, the structure, evolution, tissue distribution and function of perforin in bony fish are summarized, respectively, which will allow us to gain more insights into the perforin in lower animals and the evolution of this important pore-forming protein across vertebrates.

Effect of growth rate on transcriptomic responses to immune stimulation in wild-type, domesticated, and GH-transgenic coho salmon

BACKGROUND

Transcriptomic responses to immune stimulation were investigated in coho salmon (Oncorhynchus kisutch) with distinct growth phenotypes. Wild-type fish were contrasted to strains with accelerated growth arising either from selective breeding (i.e. domestication) or genetic modification. Such distinct routes to accelerated growth may have unique implications for relationships and/or trade-offs between growth and immune function.

RESULTS

RNA-Seq was performed on liver and head kidney in four 'growth response groups' injected with polyinosinic-polycytidylic acid (Poly I:C; viral mimic), peptidoglycan (PGN; bacterial mimic) or PBS (control). These groups were: 1) 'W': wild-type, 2) 'TF': growth hormone (GH) transgenic salmon with ~ 3-fold higher growth-rate than W, 3) 'TR': GH transgenic fish ration restricted to possess a growth-rate equal to W, and 4) 'D': domesticated non-transgenic fish showing growth-rate intermediate to W and TF. D and TF showed a higher similarity in transcriptomic response compared to W and TR. Several immune genes showed constitutive expression differences among growth response groups, including perforin 1 and C-C motif chemokine 19-like. Among the affected immune pathways, most were up-regulated by Poly I:C and PGN. In response to PGN, the c-type lectin receptor signalling pathway responded uniquely in TF and TR. In response to stimulation with both immune mimics, TR responded more strongly than other groups. Further, group-specific pathway responses to PGN stimulation included NOD-like receptor signalling in W and platelet activation in TR. TF consistently showed the most attenuated immune response relative to W, and more DEGs were apparent in TR than TF and D relative to W, suggesting that a non-satiating ration coupled with elevated circulating GH levels may cause TR to possess enhanced immune capabilities. Alternatively, TF and D salmon are prevented from acquiring the same level of immune response as TR due to direction of energy to high overall somatic growth. Further study of the effects of ration restriction in growth-modified fishes is warranted.

CONCLUSIONS

These findings improve our understanding of the pleiotropic effects of growth modification on the immunological responses of fish, revealing unique immune pathway responses depending on the mechanism of growth acceleration and nutritional availability.

Molecular characterization of three novel perforins in common carp (Cyprinus carpio L.) and their expression patterns during larvae ontogeny and in response to immune challenges

Background

In the host immune system, perforin is a cytotoxic effector molecule that eliminate virus-infected and malignant cells. Moreover, some recent studies also imply the involvement of perforin in antibacterial immunity. Common carp (Cyprinus carpio L.), one of the most economically important fish species in China, has a high susceptibility to viruses and bacteria. Thus far, in common carp, no data are available regarding the identification and immunologic function of the perforin.

Results

In the present study, the cDNA and genomic DNA sequences of three perforin isoform genes were cloned and characterized in common carp, named CcPRF1, CcPRF2 and CcPRF3. Amino acid sequences of the three CcPRFs were quite different, with identities ranged from 37.3 to 39.5%. Phylogenetic analysis showed that three CcPRFs, each in a separate sub-branch, possessed closer evolutionary relationship with other teleost perforins, especially with cyprinid fishes, than higher vertebrates. Expression analysis revealed that each CcPRF gene was differentially expressed in all of the nine tested tissues. During larvae ontogeny, each CcPRF displayed a distinct expression pattern, while with a common expression peak at 22 days post hatching (dph). Moreover, in vivo or in vitro, after stimulation with polyI:C, LPS and Aeromonas hydrophila, each CcPRF was induced significantly, with differential expression dynamics.

Conclusions

Our findings suggest that perforin might play significant roles in larval immune system and in the immune defense of common carp against viral and bacterial pathogens. Meantime, the differential expression dynamics seem to imply possible different cellular locations or functional differences across various CcPRF isoforms.

Electronic supplementary material

The online version of this article (10.1186/s12917-018-1613-y) contains supplementary material, which is available to authorized users.

Trans-cinnamic acid application for rainbow trout (Oncorhynchus mykiss): I. Effects on haematological, serum biochemical, non-specific immune and head kidney gene expression responses

The present study investigated the effects of dietary trans-cinnamic acid (CA) on pre- and post-challenge haematological, serum biochemical, non-specific immune and head kidney gene expression responses of rainbow trout, Oncorhynchus mykiss juveniles. In this regard, fish with an average weight of 17.01 ± 0.05 g were divided into five groups, and fed daily with an additive free basal diet (control); 250, 500, 750 or 1500 mg kg^-1 CA for a 60-day period. Fish were sampled every 20 days during the experiment. On days 20, 40 and 60 (the pre-challenge period), the dietary CA especially at 250 and/or 500 mg kg^-1 significantly increased blood granulocyte percentage, and serum total protein, globulin, lysozyme and total immunoglobulin values. Furthermore, dietary CA increased activities of phagocytic activity, respiratory burst and potential killing, and increased the expression levels of immune related genes [serum amyloid A (SAA), interleukin 8 (IL-8), interleukin 1, beta (IL-1β), transforming growth factor beta (TGF-β), tumor necrosis factor (TNF-α), and immunoglobulin T (IgT)] in the head kidney of fish fed with 250 and/or 500 mg kg^-1 CA. Following 60 days of feeding, fish were challenged with Yersinia ruckeri and mortality was recorded for 20 days. Highest percentage survival (%) rate was found in the 250 and/or 500 mg kg^-1 CA-supplemented feeding groups. During the post-challenge period, red blood cell (RBC) count, hematocrit (%), respiratory burst activity, and total antiprotease activity increased in fish fed with feed containing 500 mg kg^-1 content. Moreover, markedly up-regulated the expression of related genes (SAA, IL-8, IL-1β, TGF-β, TNF-α, IFN-γ and IgM) in fish fed 250, 500 and/or 750 mg kg^-1 CA. Therefore, feeding O. mykiss for 60 days with dietary CA at 250-500 mg kg^-1 CA incorporation levels can be suggested as optimal to enhance the immunity and disease resistance against Y. ruckeri.