Grass carp transforming growth factor-beta 1 (TGF-beta 1): molecular cloning, tissue distribution and immunobiological activity in teleost peripheral blood lymphocytes

Cytokine networks that suppress fish cellular immunity

Immunosuppressive cytokines are a class of cytokines produced by immune cells and certain non-immune cells that have a suppressive effect on immune function. Currently known immunosuppressive cytokines include interleukin (IL)-10, transforming growth factor beta (TGF-β), IL-35, and IL-37. Although latest sequencing technologies have facilitated the identification of immunosuppressive cytokines in fish, IL-10 and TGF-β were the most well-known ones that have been widely studied and received continuous attention. Fish IL-10 and TGF-β have been identified as anti-inflammatory and immunosuppressive factors, acting on both innate and adaptive immune systems. However, unlike mammals, teleost fish underwent a third or fourth whole-genome duplication event, which significantly expanded the gene family associated with the cytokine signaling pathway, making the function and mechanism of these molecules need further investigation. In this review, we summarize the advances of studies on fish immunosuppressive cytokines IL-10 and TGF-β since their identification, mainly focusing on production, signaling transduction, and effects on the immunological function. This review aims to expand the understanding of the immunosuppressive cytokine network in fish.

Regulatory roles of cytokines in T and B lymphocytes-mediated immunity in teleost fish

T and B lymphocytes (T and B cells) are immune effector cells that play critical roles in adaptive immunity and defend against external pathogens in most vertebrates, including teleost fish. In mammals, the development and immune response of T and B cells is associated with cytokines including chemokines, interferons, interleukins, lymphokines, and tumor necrosis factors during pathogenic invasion or immunization. Given that teleost fish have evolved a similar adaptive immune system to mammals with T and B cells bearing unique receptors (B-cell receptors (BCRs) and T-cell receptors (TCRs)) and that cytokines in general have been identified, whether the regulatory roles of cytokines in T and B cell-mediated immunity are evolutionarily conserved between mammalians and teleost fish is a fascinating question. Thus, the purpose of this review is to summarize the current knowledge of teleost cytokines and T and B cells as well as the regulatory roles of cytokines on these two types of lymphocytes. This may provide important information on the parallelisms and dissimilarities of the functions of cytokines in bony fish versus higher vertebrates, which may aid in the evaluation and development of adaptive immunity-based vaccines or immunostimulants.

Mannose-binding lectin suppresses macrophage proliferation through TGF-β1 signaling pathway in Nile tilapia

Mannose-binding lectin (MBL) is a multifunctional pattern recognition molecule, which not only mediates the recognition of pathogenic microorganisms and their products, playing an important role in innate immune defense, but also participates in adaptive immune responses of mammalian. However, it's related immune mechanism remains limited, especially the regulation of cell proliferation in early vertebrates. In this study, OnMBL was found to bind to kidney macrophages (MФ) from Nile tilapia (Oreochromis niloticus). Interestingly, OnMBL was able to reduce the proliferation of activated-MФ by regulating the cell cycle, arresting a large number of cells in the G0/G1 phase, and increasing the probability of apoptosis. More importantly, we found that the inhibition of cell proliferation by OnMBL was closely related to the evolutionarily conserved canonical transforming growth factor-beta 1 (TGF-β1) signaling pathway. Mechanistically, OnMBL could significantly increase the expression of TGF-β1, activate and regulate the downstream Smad-dependent pathway to reduce the MФ proliferation, thereby maintaining cellular homeostasis in the body's internal environment. This study represents the first description regarding the regulatory mechanisms of the MBL on cell proliferation in teleost fish, which provides a novel perspective on the understanding of the multiple function and evolutionary origins of C-type lectins in the immune system.

TGF-β1 suppresses the T-cell response in teleost fish by initiating Smad3- and Foxp3-mediated transcriptional networks

Transforming growth factor-β1 (TGF-β1) can suppress the activation, proliferation, and function of many T-cell subsets, protecting organisms from inflammatory and autoimmune disease caused by an overexuberant immune response. However, whether and how TGF-β1 regulates T-cell immunity in early vertebrates remain unknown. Here, using a Nile tilapia (Oreochromis niloticus) model, we investigated suppression of the T-cell response by TGF-β1 in teleost species. Tilapia encodes an evolutionarily conserved TGF-β1, the expression of which in lymphocytes is significantly induced during the immune response following Edwardsiella piscicida infection. Once activated, tilapia T cells increase TGF-β1 production, which in turn suppresses proinflammatory cytokine expression and inhibits T-cell activation. Notably, we found administration of TGF-β1 cripples the proliferation of tilapia T cells, reduces the potential capacity of Th1/2 differentiation, and impairs the cytotoxic function, rendering the fish more vulnerable to bacterial infection. Mechanistically, TGF-β1 initiates the TGF-βR/Smad signaling pathway and triggers the phosphorylation and nuclear translocation of Smad2/3. Smad3 subsequently interacts with several transcriptional partners to repress transcription of cytokines IL-2 and IFN-γ but promote transcription of immune checkpoint regulator CTLA4 and transcription factor Foxp3. Furthermore, TGF-β1/Smad signaling further utilizes Foxp3 to achieve the cascade regulation of these T-cell genes. Taken together, our findings reveal a detailed mechanism by which TGF-β1 suppresses the T cell-based immunity in Nile tilapia and support the notion that TGF-β1 had already been employed to inhibit the T-cell response early in vertebrate evolution, thus providing novel insights into the evolution of the adaptive immune system.

Upregulation of miR-33 Exacerbates Heat-Stress-Induced Apoptosis in Granulosa Cell and Follicular Atresia of Nile Tilapia (Oreochromis niloticus) by Targeting TGFβ1I1

High temperature affects egg quality and increases follicular atresia in teleosts. The present study aimed to explore the regulated mechanism of ovary syndrome of Nile tilapia (Oreochromis niloticus) exposed to heat stress. To this end, we conducted histological and biochemical analyses and integrated miRNA-target gene analyses. The histochemical analyses confirmed that heat stress promoted the apoptosis of granulosa cell and therefore resulted in increased follicular atresia in the ovary. Heat stress led to the differential expression of multiple miRNAs (miR-27e, -27b-3p, -33, -34a -133a-5p, and -301b-5p). In a luciferase activity assay, miR-33 bound to the 3′-untranslated region (UTR) of the TGFβ1I1 (transforming growth factor-β1-induced transcript 1) gene and inhibited its expression. A TGFβ1I1 gene signal was detected in the granulosa cells of Nile tilapia by immunohistochemical analysis. Up-regulation of the miR-33 of tilapia at 6 d and 12 d exposed to heat (34.5 °C ± 0.5 °C) had significant down-regulation of the TGFβ1I1 expression of the gene and protein in tilapia ovaries. An miRNA-target gene integrated analysis revealed that miR-33 and TGFβ1I1 function in an apoptosis-related signal pathway. The signal transduction of the vascular endothelial growth factor (VEGF) family members VEGFA and its receptor (KDR) in the heat-stressed group decreased significantly compared with the control group. Transcript-levels of the Bax and Caspase-3 as apoptotic promotors were activated and Bcl-2 and Caspase-8 as apoptotic inhibitors were suppressed in the heat-stressed tilapia. These results suggest that heat stress increases the expression of miR-33, which targets TGFβ1I1 and inhibits its expression, resulting in decreased levels of follicle-stimulating hormone and 17β-estradiol and increased apoptosis by suppressing VEGF signaling, eventually inducing follicular atresia. In conclusion, our results show that the miR-33/TGFβ1I1 axis of Nile tilapia is involved in the follicular development of broodstock, and can suppress VEGF signaling to accelerate follicular atresia. Our findings demonstrate the suppressive role of miR-33 during oocyte development in Nile tilapia.

Molecular Evolution of Transforming Growth Factor-β (TGF-β) Gene Family and the Functional Characterization of Lamprey TGF-β2

The transforming growth factor-βs (TGF-βs) are multifunctional cytokines capable of regulating a wide range of cellular behaviors and play a key role in maintaining the homeostasis of the immune system. The TGF-β subfamily, which is only present in deuterostomes, expands from a single gene in invertebrates to multiple members in jawed vertebrates. However, the evolutionary processes of the TGF-β subfamily in vertebrates still lack sufficient elucidation. In this study, the TGF-β homologs are identified at the genome-wide level in the reissner lamprey (Lethenteron reissneri), the sea lamprey (Petromyzon marinus), and the Japanese lamprey (Lampetra japonica), which are the extant representatives of jawless vertebrates with a history of more than 350 million years. The molecular evolutionary analyses reveal that the lamprey TGF-β subfamily contains two members representing ancestors of TGF-β2 and 3 in vertebrates, respectively, but TGF-β1 is absent. The transcriptional expression patterns show that the lamprey TGF-β2 may play a central regulatory role in the innate immune response of the lamprey since it exhibits a more rapid and significant upregulation of expression than TGF-β3 during lipopolysaccharide stimuli. The incorporation of BrdU assay reveals that the lamprey TGF-β2 recombinant protein exerts the bipolar regulation on the proliferation of the supraneural myeloid body cells (SMB cells) in the quiescent and LPS-activated state, while plays an inhibitory role in the proliferation of quiescent and activated leukocytes in lampreys. Furthermore, caspase-3/7 activity analysis indicates that the lamprey TGF-β2 protects SMB cells from apoptosis after serum deprivation, in contrast to promoting apoptosis of leukocytes. Our composite results offer valuable clues to the origin and evolution of the TGF-β subfamily and imply that TGF-βs are among the most ancestral immune regulators in vertebrates.

Dermal fibroblast from superficial layers of pig skin exhibits more proliferative capacity than that from deep layers

OBJECTIVE

To further examine the feasibility of using pigs as an animal model for the study of dermal fibroblast heterogeneity and to explore the proliferative capacity of dermal fibroblasts from different layers of pig skin in vitro and in vivo.

MATERIAL AND METHODS

Cultured superficial and deep dermal fibroblasts were subjected to cell growth assay, cell cycle analysis, immunocytochemical staining and western blotting for proliferating cell nuclear antigens. Moreover, skin samples autografted with superficial/deep dermal fibroblasts were subjected to immunohistochemical staining and western blotting for proliferating cell nuclear antigen.

RESULTS

The cell growth assay showed that the growth curve of the superficial dermal fibroblast was progressively higher than that of the deep layer. The cell cycle analysis showed that the (G2+S) percentage of the superficial dermal fibroblasts was significantly higher than that of the deep layer fibroblasts. The immunocytochemical staining and western blotting showed that the expression of proliferating cell nuclear antigen in the cultured superficial dermal fibroblast was significantly higher than that of the deep layer cells. The immunohistochemical staining showed that the positive rate of proliferating cell nuclear antigen in the skin samples autografted with the superficial dermal fibroblast was significantly higher than that of the deep layer.

CONCLUSIONS

This study has demonstrated that similar to human dermal fibroblasts, dermal fibroblasts from different layers of pig skin exhibit distinct proliferative capacity, which increases the feasibility of using pigs as an animal model for future studies on the heterogeneity of dermal fibroblasts.

Dietary supplementation of β-conglycinin, with or without sodium butyrate on the growth, immune response and intestinal health of hybrid grouper

We investigated the effects of low and high doses of β-conglycinin and the ameliorative effects of sodium butyrate (based on high-dose β-conglycinin) on the growth performance, serum immunity, distal intestinal histopathology, and gene, protein expression related to intestinal health in hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂). The results revealed that the instantaneous growth rate (IGR) of grouper significantly increased, decreased, and increased in the low-dose β-conglycinin (bL), high-level β-conglycinin (bH) and high-level β-conglycinin plus sodium butyrate (bH-NaB), respectively. The feed coefficient ratio (FCR) was significantly increased in the bH and bH-NaB, serum levels of IFN-γ, IL-1β, and TNF-α were upregulated in the bH. The intestinal diameter/fold height ratio was significantly increased in the bH. Furthermore, there were increases in nitric oxide (NO), total nitric oxide synthase (total NOS), and peroxynitrite anion (ONOO-) in the bH, and decreases in total NOS and ONOO- in the bH-NaB. In the distal intestine, IL-1β and TGF-β1 mRNA levels were downregulated and upregulated, respective in the bL. The mRNA levels of TNF-α and IL-6 were upregulated in the bH, and downregulated in the bH-NaB, respectively. Occludin, claudin3 and ZO-3 mRNA levels were upregulated in the bL, downregulated in the bH and then upregulated in the bH-NaB. No significant differences were observed in the mRNA levels of IFN-γ and jam4. And the p-PI3K p85Tyr458/total PI3K p85 value was significantly increased in the bH and then decreased in the bH-NaB, and the total Akt value was significantly increased in the bH. These indicate β-conglycinin has a regulatory effect on serum immunity and affect distal intestinal development by modulating distal intestinal injury-related parameters. Within the distal intestinal tract, low- and high-dose β-conglycinin differentially affect immune responses and tight junctions in the distal intestine, which eventually manifests as a reduction in growth performance. Supplementing feed with sodium butyrate might represent an effective approach for enhancing serum immunity, and protects the intestines from damage caused by high-dose β-conglycinin.

Chronic chlorpyrifos exposure induces oxidative stress, apoptosis and immune dysfunction in largemouth bass (Micropterus salmoides)

This study was undertaken to (a) evaluate the destructive effects of chronic exposure to low-dose of chlorpyrifos (CPF) on antioxidant system and immune function in largemouth bass (Micropterus salmoides), and (b) to examine whether dietary supplementation of curcumin can mitigate the adverse effects induced by CPF contamination. The experiment consisted of three groups (with three replicates, 30 fish per replicate) which lasted for 60 days: A control group (without CPF exposure or CU application), CP group (exposed to 0.004 mg/L of CPF), and CU group (exposed to 0.004 mg/L of CPF and fed a diet containing 100 mg curcumin per kg feed). The results showed that CPF contamination leads to reduced weight gain, severe histopathological lesions, decreased activity of antioxidant enzymes and down-regulated expression of antioxidant-related genes. Moreover, CPF upregulated the expression of pro-inflammatory genes such as TNF-α, IL-8, IL-15, downregulated anti-inflammatory genes TGF-β1, IL-10, and promoted apoptosis through overexpression of Caspase-3, Caspase-8, caspase-9 and Bax. In addition, curcumin supplementation showed significant improvement in oxidative stress, apoptosis and immune dysfunction, but the improved effect gradually weakened during the exposure last. Gas chromatography-mass spectrometry (GC-MS) analysis for accumulation of CPF in muscle supported the changes of general physiological structure, excessive apoptotic responses, abnormal antioxidant and immune system functions and posed potential human health risks to children based on target hazard quotient. These results suggested that chronic exposure to CPF can cause oxidative stress, apoptosis and immune dysfunction, and that curcumin have the potential to reduce pesticides residues in fish. This also highlights the importance of monitoring pesticides residues in aquatic products and aquaculture aquatic environments.

Molecular characterization, expression and functional analysis of TGFβ1-b in crucian carp (Carassius carassius)

Transforming growth factor β1 (TGFβ1) is a polyfunctional cytokine with important roles in growth, differentiation and immune function in various animals. In this study, PCR, bioinformatics, real-time quantitative PCR, prokaryotic expression, protein purification and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-TOF-MS) were applied to investigate the structural features and function of TGFβ1-b in crucian carp. The complete coding sequence (CDS) of TGFβ1-b was 1134 bp in length and was submitted to GenBank (ID: MH473141). TGFβ1-b encoded a putative protein of 377 amino acids and included a signal peptide consisting of 22 amino acids. TGFβ1-b was relatively conservative in fish and distant from mammals in terms of evolutionary relationship. TGFβ1-b was found to be expressed in various tissues, with the highest expression in the kidney. The expressions of TGFβ1-b in muscle, heart and liver were increased with the addition of Rhodopseudomonas palustris, Bacillus subtilis and Enterococcus faecium at 30 days (p < 0.01). While, the expressions of SMAD2, SMAD3 and SMAD7 were also up-regulated with the addition of R. palustris at 20 days (p < 0.01). The expression of TGFβ1-b could be affected by time and group factors (p < 0.05). Moreover, the expression vector TGFβ1-b-pDE2 was successfully constructed. Prokaryotic expression indicated that a 43 kDa target protein was obtained after induction with 1.5 mM isopropyl-beta-D-thiogalactopyranoside (IPTG) for 3.5 h at 37 °C for 200 r/h. The activities of alkaline phosphatase and lysozyme in injection TGFβ1-b protein group (ITg) and feeding broken bacterial liquid group (BTg) were significantly increased at 24 h (p < 0.01). And the activities of superoxide dismutase in ITg were significantly increased at 36 h (p < 0.01). Besides, the expressions of heat shock protein 30 and heat shock protein 47 in ITg and BTg were significantly increased (p < 0.01). Whereas, the expression of interleukin-11 was significantly reduced (p < 0.01). These results indicated that TGFβ1-b protein might play a role in immunity of crucian carp.

Identification of adhesion-associated DNA methylation patterns in the peripheral nervous system

Schwann cells are unique glial cells in the peripheral nervous system. These cells provide a range of cytokines and nutritional factors to maintain axons and support axonal regeneration. However, little is known concerning adhesion-associated epigenetic changes that occur in Schwann cells after peripheral nerve injury (PNI). In the present study, adhesion-associated DNA methylation biomarkers were assessed between normal and injury peripheral nerve. Specifically, normal Schwann cells (NSCs) and activated Schwann cells (ASCs) were obtained from adult Wistar rats. After the Schwann cells were identified, proliferation and adhesion assays were used to assess differences between NSCs and ASCs. Methylated DNA immunoprecipitation-sequencing and bioinformatics analysis were used to identify and analyze the differentially methylated genes. Reverse transcription-quantitative PCR was performed to assess the expression levels of adhesion-associated genes. In the present study, the proliferation and adhesion assays demonstrated that ASCs had a more robust proliferative activity and adhesion compared with NSCs. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were performed to identify methylation-associated biological processes and signaling pathways. Protein-protein interaction network analysis revealed that Fyn, Efna1, Jak2, Vav3, Flt4, Epha7, Crk, Kitlg, Ctnnb1 and Ptpn11 were potential markers for Schwann cell adhesion. The expression levels of several adhesion-associated genes, such as vinculin, BCAR1 scaffold protein, collagen type XVIII α1 chain and integrin subunit β6, in ASCs were altered compared with those in NSCs. The current study analyzed adhesion-associated DNA methylation patterns of Schwann cells and identified candidate genes that may potentially regulate Schwann cell adhesion in Wistar rats before and after PNI.

Transcriptome Analysis of Paralichthys olivaceus Erythrocytes Reveals Profound Immune Responses Induced by Edwardsiella tarda Infection

Unlike mammalian red blood cells (RBCs), fish RBCs are nucleated and thus capable of gene expression. Japanese flounder (Paralichthys olivaceus) is a species of marine fish with important economic values. Flounder are susceptible to Edwardsiella tarda, a severe bacterial pathogen that is able to infect and survive in flounder phagocytes. However, the infectivity of and the immune response induced by E. tarda in flounder RBCs are unclear. In the present research, we found that E. tarda was able to invade and replicate inside flounder RBCs in both in vitro and in vivo infections. To investigate the immune response induced by E. tarda in RBCs, transcriptome analysis of the spleen RBCs of flounder challenged with E. tarda was performed. Six sequencing libraries were constructed, and an average of 43 million clean reads per library were obtained, with 85% of the reads being successfully mapped to the genome of flounder. A total of 1720 differentially expressed genes (DEGs) were identified in E. tarda-infected fish. The DEGs were significantly enriched in diverse Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, especially those associated with immunity, disease, and infection. Ninety-one key DEGs involved in 12 immune-related pathways were found to form extensive interaction networks. Twenty-one genes that constituted the hub of the networks were further identified, which were highly regulated by E. tarda and involved in a number of immune processes, notably pathogen recognition and signal transduction, antigen processing and presentation, inflammation, and splicing. These results provide new insights into the immune role of flounder RBCs during bacterial infection.

Molecular and functional characterization of the indoleamine 2,3-dioxygenase in grass carp (Ctenopharyngodon idella)

Indoleamine 2,3-dioxygenase (IDO) is a kind of dioxygenase that can catalyze the degradation of levo-tryptophan (L-Trp) and plays key roles in immune tolerance. In this study, the IDO gene was cloned and functionally characterized from grass carp (gcIDO). The results showed that gcIDO overexpressed in GCO cells could catalyze the degradation of L-Trp through the L-Trp - kynurenine pathway, and this activity could be promoted by δ-aminolevulinic acid (ALA) while inhibited by levo-1-methyl tryptophan (L-1MT). Moreover, gcIDO was constitutively expressed in various tissues, and its expression could be significantly up-regulated by LPS and Poly (I:C) in peripheral blood leukocytes (PBLs). Furthermore, recombinant TGF-β1 of grass carp could up-regulate the expression of IDO, TGF-β1, CD25, and Foxp3 in PBLs, indicating that the TGF-β1/IDO pathway is present in fish. In the soybean meal induced enteritis (SBMIE) model, the expression of gcIDO in the intestine was up-regulated significantly, demonstrating that gcIDO may play an immunoregulatory role in SBMIE. Taken together, these data suggest that the IDO plays multiple roles in the immunity of fish.

Changes in the liver transcriptome of farmed Atlantic salmon (Salmo salar) fed experimental diets based on terrestrial alternatives to fish meal and fish oil

Background

Dependence on marine natural resources threatens the sustainability of Atlantic salmon aquaculture. In the present study, Atlantic salmon fed for 14 weeks with an experimental diet based on animal by-products and vegetable oil (ABP) exhibited reduced growth performance compared with others fed a fish meal/fish oil based experimental diet (MAR) and a plant protein/vegetable oil-based experimental diet (VEG). To characterize the molecular changes underlying the differences in growth performance, we conducted a 44 K microarray study of the liver transcriptome of the three dietary groups.

Results

The microarray experiment identified 122 differentially expressed features (Rank Products, PFP < 10%). Based on their associated Gene Ontology terms, 46 probes were classified as metabolic and growth-relevant genes, 25 as immune-related, and 12 as related to oxidation-reduction processes. The microarray results were validated by qPCR analysis of 29 microarray-identified transcripts. Diets significantly modulated the transcription of genes involved in carbohydrate metabolism (gck and pfkfb4), cell growth and proliferation (sgk2 and htra1), apoptosis (gadd45b), lipid metabolism (fabp3, idi1, sqs), and immunity (igd, mx, ifit5, and mhcI). Hierarchical clustering and linear correlation analyses were performed to find gene expression patterns among the qPCR-analyzed transcripts, and connections between them and muscle and liver lipid composition. Overall, our results indicate that changes in the liver transcriptome and tissue lipid composition were driven by cholesterol synthesis up-regulation by ABP and VEG diets, and the lower carbohydrate intake in the ABP group. Two of the microarray-identified genes (sgk2 and htra1) might be key to explaining glucose metabolism regulation and the dietary-modulation of the immune system in fish. To evaluate the potential of these genes as predictive biomarkers, we subjected the qPCR data to a stepwise discriminant analysis. Three sets of no more than four genes were found to be able to predict, with high accuracy (67–94%), salmon growth and fatty acid composition.

Conclusions

This study provides new findings on the impact of terrestrial animal and plant products on the nutrition and health of farmed Atlantic salmon, and a new method based on gene biomarkers for potentially predicting desired phenotypes, which could help formulate superior feeds for the Atlantic salmon aquaculture industry.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5188-6) contains supplementary material, which is available to authorized users.

Identification of an intercellular cell adhesion molecule-1 homologue from grass carp: Evidence for its involvement in the immune cell adhesion in teleost

Intercellular cell adhesion molecule-1 (ICAM-1) is a single-chain transmembrane glycoprotein which plays key roles in transendothelial migration of leukocytes and interaction between antigen presenting cells and T cells. In teleost, information of cell adhesion-related molecules is still lacking. In this study, we identified a gene from grass carp sharing similar exon and intron organization with human ICAM-1. Cloning and in silico analysis of its homologues in zebrafish and other two cyprinid fishes, respectively demonstrated the existence of the gene in these fishes. Moreover, the molecular features of these genes in fishes were conserved compared with human ICAM-1. In grass carp, the transcripts of this gene were detected with high levels in heart and liver and its mRNA expression in headkidney leukocytes was induced by Il-1β. Overexpression of this molecule in COS-7 cells could increase the adhesion of the cells with grass carp peripheral blood lymphocytes (PBLs), and the adhesion was further enhanced by lipopolysaccharide stimulation on PBLs. Further studies revealed that the mRNA levels of lymphocyte function-associated antigen-1, a ligand for ICAM-1, were much higher in the PBLs adhering to the COS-7 cells with overexpressing this molecule than in the PBLs alone. These results collectively showed that the newly cloned cDNA encodes grass carp intercellular cell adhesion molecule-1 (Icam-1) and it can mediate the adhesion of PBLs. This provides functional evidence for the existence of Icam-1 in teleost and will facilitate investigation on the transendothelial migration of leukocytes in fish species.

MicroRNA-340 inhibits squamous cell carcinoma cell proliferation, migration and invasion by downregulating RhoA

BACKGROUND

MicroRNAs are reported to play an important role in tumor growth and metastasis, including squamous cell carcinoma (SCC). Accumulative evidence has revealed that dysregulated miR-340 expression contributed to the carcinogenesis and development of various cancers.

OBJECTIVE

The aim of the current study was to investigate the role and the underlying mechanism of miR-340 in SCC cell proliferation, migration and invasion.

METHODS

Quantitative real-time PCR was performed to examine the expression of miR-340 in SCC tissues and cell lines. The function of miR-340 in SCC was investigated through Cell Counting Kit-8, wound healing, transwell migration and invasion assays. Bioinformatics analysis, luciferase reporter assay, western blotting and immunohistochemical analysis were conducted to predict and confirm the target gene of miR-340.

RESULTS

In the present study, we first found that miR-340 was significantly decreased in both SCC tissues and cell lines. Moreover, ectopic expression of miR-340 remarkably attenuated SCC cell proliferation, migration and invasion, whereas inhibition of endogenous miR-340 promoted SCC cell proliferation, migration and invasion in vitro. Our subsequent bioinformatics analysis and luciferase reporter assay showed that RhoA was a novel direct target of miR-340 in SCC cells, and the knockdown of RhoA expression rescued the effects of miR-340 inhibition on SCC cell proliferation, migration and invasion. More importantly, the expression of RhoA and miR-340 was negatively correlated in SCC tissues.

CONCLUSION

Our findings demonstrate the tumor suppressor role of miR-340 in SCC by directly regulating RhoA. Therefore, restoration of miR-340 expression can be a potential therapeutic approach for SCC treatment.

Under control: The innate immunity of fish from the inhibitors' perspective

The innate immune response involves a concerted network of induced gene products, preformed immune effectors, biochemical signalling cascades and specialised cells. However, the multifaceted activation of these defensive measures can derail or overshoot and, if left unchecked, overwhelm the host. A plenty of regulatory devices therefore mediate the fragile equilibrium between pathogen defence and pathophysiological manifestations. Over the past decade in particular, an almost complete set of teleostean sequences orthologous to mammalian immunoregulatory factors has been identified in various fish species, which prove the remarkable conservation of innate immune-control concepts among vertebrates. This review will present the current knowledge on more than 50 teleostean regulatory factors (plus additional fish-specific paralogs) that are of paramount importance for controlling the clotting cascade, the complement system, pattern-recognition pathways and cytokine-signalling networks. A special focus lies on those immunoregulatory features that have emerged as potential biomarker genes in transcriptome-wide research studies. Moreover, we report on the latest progress in elucidating control elements that act directly with immune-gene-encoding nucleic acids, such as transcription factors, hormone receptors and micro- and long noncoding RNAs. Investigations into the function of teleostean inhibitory factors are still mainly based on gene-expression profiling or overexpression studies. However, in support of structural and in-vitro analyses, evidence from in-vivo trials is also available and revealed many biochemical details on piscine immune regulation. The presence of multiple gene copies in fish adds a degree of complexity, as it is so far hardly understood if they might play distinct roles during inflammation. The present review addresses this and other open questions that should be tackled by fish immunologists in future.

Identification of two Stat3 variants lacking a transactivation domain in grass carp: New insights into alternative splicing in the modification of teleost Stat3 signaling

Signal transducer and activator of transcription 3 (STAT3) is a member of the STAT family in response to cytokines and growth factors. In mammals, alternative splicing of STAT3 generates STAT3α and STAT3β, which have distinct and overlapping functions. In the previous study, we have identified two spliceforms of Stat3α (Stat3α1 and Stat3α2) possessing all functional domains of Stat3 in grass carp (Ctenopharyngodon idella). In the present study, two Stat3β variants (Stat3β1 and Stat3β2) without C-terminal transactivation domain were isolated from this species, and their transcripts were ubiquitously expressed in all examined tissues with the highest levels in liver. Further studies showed that Stat3β1/2 had the ability to translocate into the nucleus upon activation, indicating their roles in transcriptional regulation. In support of this notion, grass carp Stat3β1 and Stat3β2 displayed the abilities to inhibit Interleukin-10 (Il-10) signaling and competitively impaired the transcriptional activities of Stat3α1/2. In particular, similar to their mammalian counterparts, grass carp Stat3β1 and Stat3β2 could enhance Stat3α1/2 phosphorylation upon cytokine stimulation. Interestingly, stat3β1 and stat3β2 transcripts were also found in zebrafish (Danio rerio) and goldfish (Carassius auratus), and each variant in these teleosts is generated through similar alternative splicing events, including exon skipping and intron retention. This highlights a conserved splicing event of stat3 gene during vertebrate evolution and indicates a potential physiological significance of generating unique Stat3 variants in fish. These results, along with the findings regarding Stat3α1/2, demonstrate the existence of Stat3 isoforms with functional diversity and redundancy in teleosts. It leads to the hypothesis that teleost-specific spliceforms of Stat3 gene may contribute to the complexity of Stat3 signaling in fishes, thereby benefiting them to adapt to evolution and environmental changes.

Identification and functional evaluation of two STAT3 variants in grass carp: Implication for the existence of specific alternative splicing of STAT3 gene in teleost

A STAT family member, STAT3, becomes activated as a DNA binding protein in response to cytokines and growth factors. In teleost, STAT3 cDNA has been cloned and identified in a few species, but only a single STAT3 transcript is revealed in these studies. In the present study, two variants of STAT3 gene generated by alternative splicing were isolated from grass carp and nominated as STAT3α1 and STAT3α2 based on the homology with their mammalian orthologs. In particular, the homologs of STAT3α1/2 were also found in various fish species, including zebrafish, takifugu, tilapia, medaka and goldfish. Intriguingly, sequence alignment and genomic structure analysis revealed that fish STAT3α1/2 are generated through similar alternative splicing events, implying the potential physiological significance of generating STAT3 variants in fish. Grass carp STAT3α1/2 (gcSTAT3α1/2) were ubiquitously expressed although the transcript levels of STAT3α2 were markedly higher than STAT3α1 in all examined tissues. In vivo and in vitro studies showed that the expression patterns of these two variants were similar under the stimulation of immune stimuli. To reveal the role of gcSTAT3α1/2 in fish immunity, their phosphorylation and involvement in IL-17A/F1 mRNA expression were demonstrated in grass carp peripheral blood lymphocytes upon LPS or PHA challenge, providing evidence for the functional conservation of STAT3 signaling in fish. These findings also raise a question of whether both gcSTAT3α1/2 participate in transcriptional regulation in fish. Actually, our results showed that both of them had the ability to translocate into the nucleus upon activation, and to amplify IL-10 signaling, indicating the existence of STAT3 isoforms with functional redundancy in teleost.

Dermal Fibroblasts from Different Layers of Pig Skin Exhibit Different Profibrotic and Morphological Characteristics

In vitro studies of human dermal fibroblast (DF) heterogeneity have long been reported, yet in vivo studies and related research on animals are rare. The objectives of the study were to determine whether the DFs of pigs exhibit heterogeneity and to identify an animal model for the in vivo study of DF heterogeneity. The skin of three female red Duroc pigs (FRDPs) was separated into six layers, and the second and fifth layers (i.e., the superficial and deep dermis) were used in the establishment of wound models and cell cultures. To create the wound models, 54 tongue-shaped flaps were created on one side of the dorsum, and the underlying dermis was then fully replaced with the superficial or deep dermis (the superficial and deep groups, respectively). Skin samples were harvested at postoperative weeks 1, 2, and 3 for measurements of the normal and wounded skin thicknesses. Cells cultured from the superficial and deep dermis (i.e., superficial and deep DFs) were subjected to quantitative estimation of collagen and electron microscopy. The wounded skin thickness in the deep group was significantly greater than that in the superficial group. In contrast with the long deep DFs, the superficial DFs were short and exhibited microvilli-like cell surface projections. Compared with the superficial DFs, the deep DFs exhibited a greater density of rough endoplasmic reticulum and produced significantly more collagen. Similar to humans, FRDPs exhibit DF heterogeneity and should thus be a good animal model for in vivo studies of DF heterogeneity. Anat Rec, 299:1585-1599, 2016. © 2016 Wiley Periodicals, Inc.

Dissecting the role of transforming growth factor-β1 in topmouth culter immunobiological activity: a fundamental functional analysis

Transforming growth factor-β1 (TGF-β1) has been proven to function primarily in mammalian immunobiological activity, but information regarding the immune role of TGF-β1 in teleosts is limited. In the present study, we describe the cDNA cloning and characterization of the TGF-β1 molecule in the topmouth culter. TGF-β1 is highly expressed in immune-related tissues of the culter, including the thymus, head kidney, and spleen. The recombinant culter TGF-β1 (cTGF-β1) was successfully expressed and purified in vitro, and the effects of cTGF-β1 on the mRNA expression of pro-inflammatory cytokines, such as TNF-α and IL-1β, in the absence or presence of LPS was determined in culter peripheral blood leukocytes. cTGF-β1 was found to have bipolar properties in inflammatory reactions. Additionally, to assess the immune role of teleost TGF-β1 in vivo, the expression of TGF-β1 in the culter thymus and spleen tissues induced by poly I:C were also examined. The expression of TGF-β1 was obviously up-regulated, as shown in the cell lines. However, the peak time of cTGF-β1 expression in the cell lines occurred significantly earlier than in the organic tissues under the same inducer, suggesting that the response of the teleost TGF-β1 molecule to exogenous infection depends on a more complicated signalling pathway in vivo than in vitro.

The Function of Fish Cytokines

What is known about the biological activity of fish cytokines is reviewed. Most of the functional studies performed to date have been in teleost fish, and have focused on the induced effects of cytokine recombinant proteins, or have used loss- and gain-of-function experiments in zebrafish. Such studies begin to tell us about the role of these molecules in the regulation of fish immune responses and whether they are similar or divergent to the well-characterised functions of mammalian cytokines. This knowledge will aid our ability to determine and modulate the pathways leading to protective immunity, to improve fish health in aquaculture.

Prognostic significance of Dicer expression in hepatocellular carcinoma

Dicer is a RNaseIII endonuclease of the microRNA processing pathway, which is implicated in carcinogenesis of various types of human cancer. The present study assessed the expression level of Dicer in hepatocellular carcinoma (HCC) tissue to evaluate its association with HCC tumorigenesis. A low expression of Dicer was significantly associated with a shorter postoperative survival time of patients with HCC, which was assessed using the log-rank test with Kaplan-Meier survival analysis. Multivariate analysis identified that Dicer expression was an independent predictor for HCC outcome (relative risk, 0.660; 95% confidence interval, 0.506–0.861; P=0.002). A functional assay demonstrated that Dicer overexpression inhibited the proliferation and promoted the apoptosis of HCC cells. In addition, a Transwell assay revealed that Dicer markedly inhibited the migration and invasion of HCC cells. The present findings indicate that Dicer expression modified the outcomes of HCC patients by inhibiting proliferation, promoting apoptosis and inhibiting metastasis of HCC cells.

Evaluation the effect of thiamin deficiency on intestinal immunity of young grass carp (Ctenopharyngodon idella)

Our study explored the effect of dietary thiamin on growth and immunity (intestine, head kidney, spleen and liver) of young grass carp (Ctenopharyngodon idella). Fish were fed diets containing six graded levels of thiamin at 0.12-2.04 mg/kg diet for 8 weeks. The percentage weight gain (PWG), feed intake and feed efficiency were lower in fish fed the 0.12 mg/kg diet. Thiamin deficiency decreased complement 3 content, lysozyme (LA) and acid phosphatase activities, mRNA levels of hepcidin and interleukin (IL) 10, elevated mRNA levels of interferon γ2, tumor necrosis factor α, IL-1β and IL-8 in intestine, head kidney, spleen and liver. The mRNA levels of inhibitor protein-κBα, target of rapamycin (TOR) and NF-E2-related factor 2 (Nrf2), the activities and mRNA levels of copper/zinc superoxide dismutase, manganese superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase and glutathione reductase were down-regulated, mRNA levels of myosin light-chain kinase (MLCK), IκB kinases (IKKβ and IKKγ), nuclear factor κB P65 (NF-κB P65) and Kelch-like-ECH-associated protein 1a (Keap1a) were up-regulated in the intestine of fish fed the thiamin-deficient diet. Additionally, thiamin deficiency decreased claudin b, c and 3, ZO-1 and occludin mRNA levels in each intestinal segment, increased claudin 12 and claudin 15a mRNA levels in distal intestine. In conclusion, thiamin deficiency decreased fish growth and immunity of intestine, head kidney, spleen and liver. The dietary thiamin requirement of young grass carp (242-742 g) based on intestinal LA activity or PWG were determined to be 1.15 or 0.90 mg/kg diet, respectively.

Cloning and primary immunological study of TGF-β1 and its receptors TβR I /TβR II in tilapia(Oreochromis niloticus)

The transforming growth factor β (TGF-β) superfamily plays critical roles in tumor suppression, cell proliferation and differentiation, tissue morphogenesis, lineage determination, cell migration and apoptosis. Recently, TGF-β1, one important member of TGF-β superfamily, is suggested as an immune regulator in the teleost. In this study, we cloned the cDNAs of TGF-β1 and its receptors, TβR I and TβR II (including three isoforms) from tilapia (Genbank accession numbers: KP754231- KP754235). A tissue distribution profile analysis indicated that TGF-β1 was highly expressed in the head kidney, gill, spleen, kidney and PBLs (peripheral blood leukocytes); TβR I only showed considerable expression in the liver; and TβR II-2 was highly expressed in the kidney, gill, liver, head kidney and heart. We determined that the mRNA expressions of TGF-β and TβR I /TβR II-2 were significantly increased in tilapia head kidney and spleen leukocytes by the stimulation of Lipopolysaccharide (LPS) or Poly I: C. We also examined their expressions in the spleen and head kidney of tilapia after IP injection of streptococcus agalactiae. The results showed that the mRNA expressions of these three genes all increased in the head kidney as early as 6 h post infection, and in the spleen 3 d post infection. In addition, the protein level of TGF-β1 was also up-regulated in the head kidney and the spleen after infection. Taken together, our data indicate that the TGF-β1-TβR I /TβR II-2 system functions potentially in tilapia immune system.

Cellular activation, expression analysis and functional characterization of grass carp IκBα: evidence for its involvement in fish NF-κB signaling pathway

IκBα is a well-known member of the inhibitors of kappa B (IκB) family that controls NF-κB signaling by blocking NF-κB translocation from cytoplasm to nucleus. In the present study, an IκBα homologue was identified from grass carp (gcIκBα), showing the structural characteristics of IκB family. Moreover, mRNA expression of this molecule in grass carp periphery blood lymphocytes (PBLs) was enhanced significantly by both LPS and PHA in a time- and dose-dependent manner, indicating the involvement of gcIκBα in fish immune response. Further analysis demonstrated that LPS but not PHA induced gcIκBα phosphorylation and protein degradation in PBLs, implying different signaling pathways mediated by LPS and PHA in gcIκBα expression regulation in grass carp PBLs. In particular, the time-dependent oscillation of gcIκBα phosphorylation and total protein levels induced by LPS is in accordance with the characteristics of mammalian IκBα phosphorylation followed by protein degradation during NF-κB activation. In support of this notion, overexpression of gcIκBα was able to block both basal and LPS-stimulated NF-κB activity in grass carp kidney cell line, indicating the negatively regulatory role of gcIκBα in NF-κB activity as seen in mammals. Therefore, our results not only reveal a dynamic variation of NF-κB activity based on the activation and expression of IκBα for the first time, but also provide the direct evidence for the involvement of IκBα in NF-κB signaling in fish immune cells.

Pro- and anti-inflammatory cytokine expression in immune organs of the common carp exposed to atrazine and chlorpyrifos

Atrazine (ATR) and chlorpyrifos (CPF) are toxic and subject to long-term in vivo accumulation in different aquatic species throughout the world. The purpose of the present study was to examine the effect of ATR, CPF and combined ATR/CPF exposure on cytokines in the head kidney and spleen of common carp (Cyprinus carpio L.). The carp were sampled after a 40-d exposure to CPF and ATR, individually or in combination, followed by a 40-d recovery to measure the mRNA expression of IL-6fam (IL-6), IL-8, TNF-α, IL-10 and TGF-β1 (TGF-β) in the head kidney and spleen tissues. These results showed that the expression of cytokines IL-6, IL-8 and TNF-α in the head kidney and spleen was upregulated following ATR, CPF and mixed ATR/CPF exposure compared with the control group. The expression of IL-10 and TGF-β mRNA was significantly inhibited in both head kidney and spleen of carp exposed to ATR, CPF and the ATR/CPF mixture. The results suggested that long-term exposure of ATR, CPF and the ATR/CPF mixture in aquatic environments can induce the dysregulation of pro-/anti-inflammatory cytokine expression. The information regarding the effects of ATR and CPF on cytokine mRNA expression generated in this study will be important information for pesticides toxicology evaluation.

Molecular identification of transcription factor Runx1 variants in grass carp (Ctenopharyngodon idella) and their responses to immune stimuli

The Runt-related transcription factor (Runx) family consists of three members, Runx1, Runx2 and Runx3 in mammals, which are involved in various biological processes. Recent studies have demonstrated that Runx1 plays critical roles in the immunity of higher vertebrates. In fish, zebrafish and fugu Runx family members have been identified, and their chromosome location, promoter usage and expression patterns have been elucidated. However, their expression profiles in immune responses are still unknown. In this study, we identified grass carp five Runx1 (gcRunx1) variants (v1-5) possibly generated through alternative promoter usage and alternative splicing. The gcRunx1 v1-3 encodes the proteins possessing intact structural characteristics of Runx family, but the putative proteins of gcRunx1 v4-5 lack a transactivation domain, an inhibitory domain and a C-terminal pentapeptide motif (VWRPY). Tissue distribution assays revealed that gcRunx1 was preferentially expressed in some immune-related tissues including thymus and spleen, indicating its potential roles in teleost immunity. The changes of gcRunx1 expression to various immune stimuli was examined in periphery blood lymphocytes, showing that gcRunx1 v1-3 mRNA levels were increased after LPS, poly I:C and PHA treatment, whereas gcRunx1 v4-5 mRNA expression were stimulated only by LPS and PHA. Furthermore, in vivo studies confirmed that bacterial challenge enhanced gcRunx1 mRNA levels. In particular, in vitro and in vivo studies revealed that gcRunx1 v4-5 mRNA expression was induced with a delayed kinetics compared with that of gcRunx1 v1-3. These findings not only provide the evidence for the involvement of gcRunx1 in immune response, but also reveal the inducible expression diversity of fish Runx1 splicing variants, thereby facilitating further elucidating the role of Runx1 in piscine immunity.

Structural and functional characterization of a TGFβ molecule from amphioxus reveals an ancient origin of both immune-enhancing and -inhibitory functions

Transforming growth factor beta (TGFβ) is a pleiotropic cytokine with important roles in mediating inflammatory response. TGFβ has been shown to be widely present in invertebrates, but little is known about its functions in immune and inflammatory responses. Moreover, structural and functional insights into TGFβ molecules in invertebrates remain completely lacking. Here we demonstrate the presence of a single TGFβ-like gene in the amphioxus Branchiostoma japonicum, Bjtgfβ, which represents the archetype of vertebrate TGFβ proteins, and displays a higher expression in the hind-gut, hepatic caecum, ovary, and gill. We also show that amphioxus TGFβ exerts both enhancing and suppressing effects on the migration of macrophages like RAW264.7, and the motif WSTD is important for TGFβ in inducing or inhibiting the migration of macrophages. Altogether, these data suggest that amphioxus TGFβ is phylogenetically and functionally similar to vertebrate TGFβ, suggesting an ancient origin of bipolar function of TGFβ proteins.

Expression of immune system-related genes during ontogeny in experimentally wounded common carp (Cyprinus carpio) larvae and juveniles

We investigated the effect of full-thickness incisional wounding on expression of genes related to the immune system in larvae and juveniles of common carp (Cyprinus carpio). The wounds were inflicted by needle puncture immediately below the anterior part of the dorsal fin on days 7, 14, 28 and 49 after fertilization. We followed the local gene expression 1, 3 and 7 days after wounding by removing head and viscera before extracting RNA from the remaining part of the fish, including the wound area. In addition, we visually followed wound healing. Overall the wounds had regenerated to a point where they were microscopically indistinguishable from normal tissue by day 3 post-wounding in all but the juvenile carp wounded on day 49 post-fertilization. In these juveniles the wounded area was still visible even 7 days post-wounding. On the transcriptional level a very limited response was observed in the investigated genes as a result of the wounding. HSP70 was downregulated 1 and 3 days post-wounding in the smallest larvae. However, HSP70 was differentially expressed at different time-points in a similar manner in wounded and mock-wounded groups, thus suggesting a stress effect of the handling, which may have overshadowed some transcriptional effects of the wounding. MMP-9, TGF-β1 and IgZ1 were slightly but significantly upregulated at few time-points, while no effect of wounding was detected on the expression of IgM, C3, IL-1β and IL-6 family member M17.

Decreased expression of GATA2 promoted proliferation, migration and invasion of HepG2 in vitro and correlated with poor prognosis of hepatocellular carcinoma

Background

GATA family of transcription factors are critical for organ development and associated with progression of various cancer types. However, their expression patterns and prognostic values for hepatocellular carcinoma (HCC) are still largely unknown.

Methods

Expression of GATA transcription factors in HCC cell lines and tissues (n = 240) were evaluated by RT-qPCR, western blot and immunohistochemistry. Cellular proliferation, migration and invasion of HepG2 was evaluated by CCK-8 kit, scratch wound assay and transwell matrigel invasion assay, respectively.

Results

GATA2 expression was decreased in HCC cell lines (p = 0.056 for mRNA, p = 0.040 for protein) and tissues (p = 1.27E-25) compared with normal hepatocytes. Decreased expression of intratumoral GATA2 protein significantly correlated with elevated alpha feto-protein (p = 2.7E-05), tumor size >5 cm (p = 0.049), absence of tumor capsule (p = 0.002), poor differentiation (p = 0.005), presence of tumor thrombi (p = 0.005) and advanced TNM stage (p = 0.001) and was associated with increased recurrence rate and decreased overall survival rate by univariate (p = 1.6E-04 for TTR, p = 1.7E-04 for OS) and multivariate analyses (HR = 0.63, 95% CI = 0.43–0.90, p = 0.012 for TTR; HR = 0.67, 95% CI = 0.47–0.95, p = 0.026 for OS). RNAi-mediated knockdown of GATA2 expression significantly enhanced proliferation, migration and invasion of HepG2 cell in vitro.

Conclusions

Decreased expression of hematopoietic factor GATA2 was associated with poor prognosis of HCC following resection.

The cytokine networks of adaptive immunity in fish

Cytokines, produced at the site of entry of a pathogen, drive inflammatory signals that regulate the capacity of resident and newly arrived phagocytes to destroy the invading pathogen. They also regulate antigen presenting cells (APCs), and their migration to lymph nodes to initiate the adaptive immune response. When naive CD4+ T cells recognize a foreign antigen-derived peptide presented in the context of major histocompatibility complex class II on APCs, they undergo massive proliferation and differentiation into at least four different T-helper (Th) cell subsets (Th1, Th2, Th17, and induced T-regulatory (iTreg) cells in mammals. Each cell subset expresses a unique set of signature cytokines. The profile and magnitude of cytokines produced in response to invasion of a foreign organism or to other danger signals by activated CD4+ T cells themselves, and/or other cell types during the course of differentiation, define to a large extent whether subsequent immune responses will have beneficial or detrimental effects to the host. The major players of the cytokine network of adaptive immunity in fish are described in this review with a focus on the salmonid cytokine network. We highlight the molecular, and increasing cellular, evidence for the existence of T-helper cells in fish. Whether these cells will match exactly to the mammalian paradigm remains to be seen, but the early evidence suggests that there will be many similarities to known subsets. Alternative or additional Th populations may also exist in fish, perhaps influenced by the types of pathogen encountered by a particular species and/or fish group. These Th cells are crucial for eliciting disease resistance post-vaccination, and hopefully will help resolve some of the difficulties in producing efficacious vaccines to certain fish diseases.

Cytokine responses in the Japanese pufferfish (Takifugu rubripes) head kidney cells induced with heat-killed probiotics isolated from the Mongolian dairy products

Cytokine responses in the Japanese pufferfish (Takifugu rubripes) head kidney (HK) cells to heat-killed lactic acid bacteria probiotics isolated from the Mongolian dairy products were investigated by transcriptomic examination. The HK cells were incubated with two heat-killed bacteria, namely Lactobacillus paracasei spp. paracasei (strain 06TCa22) and L. plantarum (strain 06CC2) and the responses of 16 cytokine genes at 0 (control), 1, 4, 8, 12, 24 and 48 h post-stimulation were assayed by multiplex RT-PCR analysis (GenomeLab Genetic Analysis System, GeXPS; Beckman Coulter, Inc.). The 16 genes included in the assay were pro-inflammatory cytokines (IL-1β, IL-6, IL-17A/F-3, TNF-α and TNF-N), cell-mediated immune regulators (IL-12p35, IL-12p40 and IL-18), antiviral (I-IFN-1 and IFN-γ) and other regulatory (IL-2, IL-7, IL-15, IL-21, IL-10 and TGF-β1) cytokines. Despite the differences in the transcriptional profiles, expression of all the cytokines tested here was significantly elevated by both the probiotic bacterial stimulants compared with the unstimulated control. Therefore, this in vitro study has demonstrated the modulation of cytokine defense mechanisms in the HK cells by the two heat-killed probiotics indicating their potentiality as novel immunostimulants to fish. However, strain-dependent varied expression of important cytokines (cell-mediated immune regulators, antiviral and anti-inflammatory cytokines) suggests better efficacy of L. paracasei spp. paracasei strain as fish immunostimulant. Further in vivo studies to elucidate the cytokine regulation networks will validate our present observations. A careful evaluation of ant-inflammatory properties may be undertaken using single strain to affirm the immunostimulatory capability. Moreover, application timings and frequency to assess the longevity of immunostimulant effects and to make the application cost-effective need to be evaluated before any practical use in aquaculture.

Advances in research of fish immune-relevant genes: a comparative overview of innate and adaptive immunity in teleosts

Fish is considered to be an important model in comparative immunology studies because it is a representative population of lower vertebrates serving as an essential link to early vertebrate evolution. Fish immune-relevant genes have received considerable attention due to its role in improving understanding of both fish immunology and the evolution of immune systems. In this review, we discuss the current understanding of teleost immune-relevant genes for both innate and adaptive immunity, including pattern recognition receptors, antimicrobial peptides, complement molecules, lectins, interferons and signaling factors, inflammatory cytokines, chemokines, adaptive immunity relevant cytokines and negative regulators, major histocompatibility complexes, immunoglobulins, and costimulatory molecules. The implications of these factors on the evolutionary history of immune systems were discussed and a perspective outline of innate and adaptive immunity of teleost fish was described. This review may provide clues on the evolution of the essential defense system in vertebrates.

Establishment of a multiplex RT-PCR assay for the rapid detection of fish cytokines

To monitor the expression of cytokine genes in Japanese pufferfish, a novel platform for quantitative multiplexed analysis was developed. This custom-designed multiplex RT-PCR assay was used to analyze the expression profiles of 19 cytokine genes, including pro-inflammatory (IL-1β, IL-6, IL-17A/F3, IL-18, TNF-α, TNF-N), anti-inflammatory (IL-4/13A, IL-4/13B, IL-10), T-cell proliferation/differentiation (IL-2, IL-15, IL-21, TGF-β1), B-cell activation/differentiation (IL-7, IL-6, IL-4/13A, IL-4/13B), NK cell stimulation (IL-12p35 and IL-12p40), induction of anti-viral activity (I-IFN-1 and IFN-γ), and monocyte/macrophage progenitor cell proliferation (M-CSF1b) cytokines in head kidney cells under immune stimulatory conditions. The expression profiles were dissimilar in the unstimulated control and immune-stimulated cells. Moreover, increased expression profile was observed due to different stimulations for IL-1β, IL-6, IL-10, IL-12p35, IL-12p40, IL-21, TNF-α, TNF-N, I-IFN-1 and IFN-γ genes. These results suggest that cytokine genes could be used as biomarkers to know the immune status of fish. The constructed multiplex RT-PCR assay will enhance understanding on immune regulation by cytokines in fish.

Adenoviral 15-lipoxygenase-1 gene transfer inhibits hypoxia-induced proliferation of retinal microvascular endothelial cells in vitro

AIM

To investigate whether 15-Lipoxygenase-1 (15-LOX-1) plays an important role in the regulation of angiogenesis, inhibiting hypoxia-induced proliferation of retinal microvascular endothelial cells (RMVECs) and the underlying mechanism.

METHODS

Primary RMVECs were isolated from the retinas of C57/BL6J mice and identified by an evaluation for FITC-marked CD31. The hypoxia models were established with the Bio-bag and evaluated with a blood-gas analyzer. Experiments were performed using RMVECs treated with and without transfer Ad-15-LOX-1 or Ad-vector both under hypoxia and normoxia condition at 12, 24, 48, 72 hours. The efficacy of the gene transfer was assessed by immunofluorescence staining. Cells proliferation was evaluated by the CCK-8 method. RNA and protein expressions of 15-LOX-1, VEGF-A, VEGFR-2, eNOs and PPAR-r were analyzed by real-time reverse transcription polymerase chain reaction (RT-PCR) and Western blot.

RESULTS

Routine evaluation for FITC-marked CD31 showed that cells were pure. The results of blood-gas analysis showed that when the cultures were exposed to hypoxia for more than 2 hours, the Po2 was 4.5 to 5.4 Kpa. We verified RMVECs could be infected with Ad-15-LOX-1 or Ad-vector via Fluorescence microscopy. CCK-8 analysis revealed that the proliferative capacities of RMVECs in hypoxic group were significantly higher at each time point than they were in normoxic group (P<0.05). In a hypoxic condition, the proliferative capacities of RMVECs in 15-LOX-1 group were significantly inhibited (P<0.05). Real-time RT-PCR analysis revealed that the expressions of VEGF-A, VEGF-R2 and eNOs mRNA increased in hypoxia group compared with normoxia group (P<0.01). However, the expressions of 15-LOX-1, PPAR-r mRNA decreased in hypoxia group compared with normoxia group (P<0.01). It also showed that in a hypoxic condition, the expressions of VEGF-A, VEGF-R2 and eNOs mRNA decreased significantly in 15-LOX-1 group compared with hypoxia group (P<0.01). However, 15-LOX-1 and PPAR-r mRNA increased significantly in 15-LOX-1 group compared with hypoxia group (P<0.01). There was no significant difference of the mRNA expressions between vector group and hypoxia group (P>0.05). Western blot analysis revealed that the expressions of relative proteins were also ranked in that order.

CONCLUSION

Our results suggested that 15-LOX-1 and PPAR-r might act as a negative regulator of retinal angiogenesis. And the effect of 15-LOX-1 overexpression is an anti-angiogenic factor in hypoxia-induced retinal neovascularization (RNV). Overexpression 15-LOX-1 on RMVECs of hypoxia-induced RNV blocked signaling cascades by inhibiting hypoxia-induced increases in VEGF family. PPAR-r effect on VEGFR(2) could be an additional mechanism whereby 15-LOX-1 inhibited the hypoxia-induced RNV.

Characterization of Foxp3 gene from grass carp (Ctenopharyngodon idellus): a rapamycin-inducible transcription factor in teleost immune system

In this study, we cloned grass carp foxp3 (gcfoxp3) gene including 5' flanking region and determined its expression profiles in vivo under immunosuppressive conditions. Sequence analysis revealed that the promoter of gcfoxp3 contains AP-1, AML-1/Runx1, NF-κb and GATA-3 binding sites, which positively or negatively regulate mammalian foxp3 expression. In addition, the intron II of gcfoxp3 contains some putative binding sites including AP-1, NFAT, Smad3, RAR, CREB/ATF and FOXO1, which are corresponding to their locations in the proximal intronic enhancers of human foxp3. In an in vivo model of grass carp, an immunosuppressive agent rapamycin was showed to stimulate gcfoxp3 mRNA expression in thymus, gill, head kidney and spleen after bacterial challenge. Moreover, rapamycin increased gcFoxp3 protein levels with an additive manner in the infected fish. These findings support the involvement of fish Foxp3 in immune response and highlight a possible signaling pathway that regulates teleost Foxp3 expression.

Molecular evidence for the involvement of RORα and RORγ in immune response in teleost

In mammals, retinoid-related orphan receptors (ROR) consist of three members as RORα, RORβ and RORγ. It is well known that RORα plays a critical role in cerebellum development while RORγt directs T helper 17 (Th17) cell differentiation. So far, the knowledge on fish ROR family is limited as only zebrafish ROR family members have been characterized, showing that they play roles in embryonic and cerebellar development. In this study, we have cloned two paralogues for RORα (RORα1 and RORα2) and RORγ (RORγ1 and RORγ2) from grass carp (Ctenopharyngodon idellus). Phylogenetic analysis showed that grass carp RORα and RORγ were grouped in the clade of zebrafish RORα and RORγ, respectively. Real-time RT-PCR assay revealed that these four ROR transcripts exhibited similar expression patterns, in particular the high levels in pituitary, brain and some immune-related tissues, suggesting that all of them may play a role in endocrine and immune system of teleost. To explore the immune roles of grass carp RORα and RORγ, their expression was detected in periphery blood lymphocytes (PBLs) challenged by immune stimuli. Results showed that both RORα and RORγ mRNA levels were up-regulated by PHA but not LPS in PBLs, suggesting that their expression may be subject to different immune processes. In the same cell model, poly I:C stimulation induced RORγ1/2 but not RORα1/2 expression, pointing to the different roles of grass carp RORα and RORγ in immune response. Consistently, bacterial challenge significantly up-regulated the expression of these four ROR genes in spleen, headkidney and thymus. These results not only contribute to elucidate the roles of ROR in fish immunity but also facilitate to further clarify the existence of Th17-like cells in fish.

Cloning and expression analysis of the transforming growth factor-beta receptors type 1 and 2 in the rainbow trout Oncorhynchus mykiss

Transforming growth factor-β (TGF-β) binding to the TGF-β type I (TGFBR1) and type II (TGFBR2) receptors delivers a plethora of cell-type specific effects. Moreover, the responses to TGF-β are tuned by regulatory mechanisms at the receptor level itself. To further elucidate TGF-β family signal transduction in teleosts, we therefore cloned the first complete set of a putative TGF-β receptor complex in salmonids. Rainbow trout TGFBR1 and TGFBR2 are transmembrane proteins with a serine/threonine kinase domain and are highly conserved within vertebrates. High expression levels in muscle and brain indicate regulation of the TGF-β system in muscular and nervous systems. Lipopolysaccharide (LPS) induced expression of both receptor chains in RTgill cells while bacterial and viral mimics modulated the two receptors inversely in head kidney (HK) macrophages. In addition, T cell mitogens lowered receptor levels in HK leukocytes. These data provide the first insights into TGF-β type I and II receptor modulation during immune responses in teleost fish.

Fish T cells: recent advances through genomics

This brief review is intended to provide a concise overview of the current literature concerning T cells, advances in identifying distinct T cell functional subsets, and in distinguishing effector cells from memory cells. We compare and contrast a wealth of recent progress made in T cell immunology of teleost, elasmobranch, and agnathan fish, to knowledge derived from mammalian T cell studies. From genome studies, fish clearly have most components associated with T cell function and we can speculate on the presence of putative T cell subsets, and the ability to detect their differentiation to form memory cells. Some recombinant proteins for T cell associated cytokines and antibodies for T cell surface receptors have been generated that will facilitate studying the functional roles of teleost T cells during immune responses. Although there is still a long way to go, major advances have occurred in recent years for investigating T cell responses, thus phenotypic and functional characterization is on the near horizon.

Identification of a novel transforming growth factor-beta (TGF-beta6) gene in fish: regulation in skeletal muscle by nutritional state

Background

The transforming growth factor-β (TGF-β) family constitutes of dimeric proteins that regulate the growth, differentiation and metabolism of many cell types, including that of skeletal muscle in mammals. The potential role of TGF-βs in fish muscle growth is not known.

Results

Here we report the molecular characterization, developmental and tissue expression and regulation by nutritional state of a novel TGF-β gene from a marine fish, the gilthead sea bream Sparus aurata. S. aurata TGF-β6 is encoded by seven exons 361, 164, 133, 111, 181, 154, and 156 bp in length and is translated into a 420-amino acid peptide. The exons are separated by six introns: >643, 415, 93, 1250, 425 and >287 bp in length. Although the gene organization is most similar to mouse and chicken TGF-β2, the deduced amino acid sequence represents a novel TGF-β that is unique to fish that we have named TGF-β6. The molecule has conserved putative functional residues, including a cleavage motif (RXXR) and nine cysteine residues that are characteristic of TGF-β. Semi-quantitative analysis of TGF-β6 expression revealed differential expression in various tissues of adult fish with high levels in skin and muscle, very low levels in liver, and moderate levels in other tissues including brain, eye and pituitary. TGF-β6 is expressed in larvae on day of hatching and increases as development progresses. A fasting period of five days of juvenile fish resulted in increased levels of TGF-β6 expression in white skeletal muscle compared to that in fed fish, which was slightly attenuated by one injection of growth hormone.

Conclusion

Our findings provide valuable insights about genomic information and nutritional regulation of TGF-β6 which will aid the further investigation of the S. aurata TGF-β6 gene in association with muscle growth. The finding of a novel TGF-β6 molecule, unique to fish, will contribute to the understanding of the evolution of the TGF-β family of cytokines in vertebrates.

Bipolar properties of red seabream (Pagrus major) transforming growth factor-beta in induction of the leucocytes migration

TGF-beta is one of the pleiotropic cytokines and plays a pivotal role in immune regulation and orchestrating the subsequent healing response. Recombinant red seabream TGF-beta (rTGF-beta) mature peptide was expressed and purified under native conditions in vitro. Bio-assay showed that the rTGF-beta could significantly induce head kidney (HK) and peripheral blood (PB) leucocytes migration in a dose dependent manner, whereas the rTGF-beta suppressed HK and PB leucocyte migration when the leucocytes was activated by primed with lipopolysaccharide (LPS). Both enhancing and suppressing roles of rTGF-beta on the HKL and PBL chemotactic activity indicated that the fish TGF-beta shared the similar bipolar nature with mammalian TGF-beta. Furthermore, the results indicated that the activity of TGF-beta induction of leucocyte migration appears not to be an innate feature but function by regulation the chemokines activity. This is the first time we reported that fish TGF-beta has innate bipolar property in regulation of fish immune function.

Characterization of grass carp (Ctenopharyngodon idellus) Foxp1a/1b/2: evidence for their involvement in the activation of peripheral blood lymphocyte subpopulations

Foxp subfamily belongs to the Fox family of winged-helix transcription factors and plays critical roles in multiple biological processes including development and immunoregulation. However, little is known about the regulation and function of Foxp subfamily in fish immune system. In this study, we obtained the complete cDNAs of grass carp Foxp1a, Foxp1b and Foxp2. They possess the conserved leucine zipper domain, zinc finger domain and forkhead domain when compared with their mammalian counterparts, except that Foxp1a lacks the forkhead domain. Real-time RT-PCR analysis showed that their transcripts were mainly found in thymus, spleen and peripheral blood lymphocytes (PBLs). In grass carp PBLs, both LPS and PHA were effective in elevating Foxp1b mRNA levels but had no effect on Foxp1a mRNA, while only PHA affected Foxp2 mRNA expression. Using the same cell model, PHA was revealed to up-regulate mRNA expression of T-cell marker genes (CD4-like, CD8alpha and CD8beta) but not B-cell marker gene (IgM). Unlike PHA, LPS increased IgM mRNA level but did not affect T-cell marker gene expression. These findings suggest that PHA and LPS may act on distinct lymphocyte subpopulations in grass carp PBLs and provide evidence for the involvement of Foxp1b and Foxp2 in the activation of different lymphocyte subpopulations in grass carp.

Interplay between the TH17 and TReg cell lineages: a (co-)evolutionary perspective

The origins of the adaptive immune system and the basis for its unique association with vertebrate species have been a source of considerable speculation. In light of recent advances in our understanding of the developmental and functional links between the induced regulatory T cell and T helper 17 cell lineages, and their specialized relationship to the gut, we speculate that the co-evolution of these adaptive immune pathways might have given primitive vertebrates a means to benefit from the diversification of their commensal microbiota.

Regulation of membrane progestin receptors in the zebrafish ovary by gonadotropin, activin, TGF-beta and BMP-15

Progestin hormones are vital for inducing oocyte maturation in fish by binding to membrane progestin receptors (mPRs). The aim of this study was to examine the expression and regulation of mPRalpha and mPRbeta in zebrafish follicles. First, defolliculated fully grown oocytes were subjected to immunofluorescent staining using anti-mPRalpha and mPRbeta antibodies, and their expression on the oocyte membrane was confirmed. Second, total protein was collected from zebrafish follicles and Western blotting revealed that the level of mPRalpha and mPRbeta increased with follicle development. We have previously shown that several members of the transforming growth factor-beta (TGF-beta) superfamily, including TGF-beta1, activin-A, and bone morphogenetic protein (BMP)-15, regulate oocyte maturation in zebrafish. Therefore, the third major focus of this study was to test if these growth factors, as well as gonadotropins, regulate the expression of mPRs. Overexpression of BMP-15 significantly reduced, while knockdown of BMP-15 increased, mPRbeta levels. However, mPRalpha expression level remained unchanged with BMP-15 overexpression or knockdown. Treatment of follicles with human chorionic gonadotropin (hCG) resulted in an increased in mPRbeta, but not mPRalpha, expression levels. Activin-A induced the expression of mPRalpha and mPRbeta in a dose- and time-dependent manner. On the other hand, TGF-beta1 treatment suppressed the expression of mPRbeta, but not mPRalpha. Taken together, these findings further support the role of mPRs in oocyte maturation and suggest that gonadotropins, BMP-15, activin-A, and TGF-beta1 exert their regulatory effects on oocyte maturation in part by regulating mPR expression.