Cloning and expression analysis of two pro-inflammatory cytokines, IL-1β and IL-8, in haddock (Melanogrammus aeglefinus)

Molecular characterization and expression analysis of interleukin-1 beta in Japanese eel (Anguilla japonica)

Interleukin 1-beta (IL-1B) is a key proinflammatory cytokine involved in disease resistance. In recent years, il-1β genes from several teleosts have been cloned. The Japanese eel (Anguilla japonica) is an evolutionarily primitive fish widely farmed in East Asia. The il-1β gene has not yet been cloned from Japanese eel. In this study, the complete cDNA of il-1β was successfully sequenced from peripheral leukocytes through the rapid amplification of cDNA ends. The il-1β gene consists of five exons and four introns, and the full-length cDNA spans 1204 bp, comprising a 99-bp 5' untranslated region, a 750-bp coding sequence, and a 355-bp 3' untranslated region. The deduced amino acid sequence includes a consensus IL-1 family signature but lacks both a signal peptide and an IL-1 converting enzyme cleavage site, similar to other teleost IL-1B proteins. Homology analysis revealed that Japanese eel IL-1B is highly conserved within the order Anguilliformes, sharing the highest similarity with American eel (Anguilla rostrata), followed by conger eel (Conger myriaster). Tissue expression analysis showed that il-1β is constitutively expressed in multiple tissues, with high expression in peripheral leukocytes and the spleen; moderate expression in the gill, liver, head kidney, trunk kidney, and intestine; and low expression in the heart, stomach, skin, and muscle. In vitro stimulation with zymosan, polyinosinic-polycytidylic acid, and lipopolysaccharide upregulated il-1β expression in peripheral leukocytes.

Contribution of interleukins in the regulation of teleost fish immunity: A review from the perspective of regulating macrophages

Interleukins (ILs) are potent secreted regulators of a wide range of cell types and cellular activities, particularly in the immune system. They are able to participate in intercellular communication in homeostasis and disease, thereby exerting immune functions. Macrophages serve as the innate immune cells of vertebrates and play a pivotal role in defending against and eliminating external pathogens. In mammals, the immune response mounted by macrophages is intricately linked to ILs. Given the fact that teleost fish have evolved an innate immune system that closely resembles those of mammals, particularly in terms of the functionality of macrophages, raises the intriguing possibility that the regulatory function of ILs in macrophage-mediated immunity might be evolutionarily conserved across both mammal and teleost fish lineages. Consequently, from the perspective of interleukin regulation of macrophages, this review outlines the relationship between ILs and macrophages in teleost fish, and elucidates the regulatory role of ILs of immune cell function in teleost fish, thereby contributing to our understanding of the key role of these cytokines in the prevention and control of aquaculture diseases.

Evaluation of three fish-derived probiotic bacteria replacing antibiotics on growth, immunity, gut morphology and disease resistance in juvenile olive flounder Paralichthys olivaceus fed reduced fish meal diets

A basal diet without feed additives was used as a control (CON) and three diets were formulated by supplementing with Bacillus subtilis WB60 at 1 × 108 CFU/g (Pro-A), B. subtilis SJ10 at 1 × 108 CFU/g (Pro-B), Enterococcus faecium SH30 at 1 × 107 CFU/g (Pro-C), and two other diets supplementing with antibiotics such as amoxicillin (AMO) at 4 g/kg and oxytetracycline (OTC) at 4 g/kg of the basal diet. A total of 450 fish averaging 12.1 ± 0.09 g (mean ± SD) were fed one of the six experimental diet groups in triplicates for 8 weeks. In disease resistance test, 45 fish from each group were intraperitoneally injected with the pathogenic bacteria, Edwardsiella tarda, and mortality was recorded for 15 days. At the end of 8-week feeding trial, weight gain, specific growth rate and feed efficiency of fish fed the Pro-A diet were significantly greater than those of fish fed the CON, OTC and AMO diets (p < 0.05). Furthermore, feeding efficiency and protein efficiency ratio of fish fed the Pro-A diet were significantly greater than those of fish fed the CON, OTC and AMO diets. Serum aspartate aminotransferase levels were significantly greater in fish fed the Pro-B diet than in those fed the Pro-A diet. The lysozyme activity of fish fed the Pro-A, Pro-B and Pro-C diets was significantly greater than that of the CON, OTC and AMO diets. The myeloperoxidase activity of fish fed the Pro-A diet was significantly greater than that of the fish fed the CON and AMO diets. The flounder growth hormone levels of fish fed the Pro-A, Pro-B, Pro-C and AMO diets were significantly greater than that of the fish fed the CON diet. The interleukin 1β gene expression levels in fish fed the Pro-B and Pro-C diets were significantly greater than those in fish fed the CON, OTC and AMO diets. The interleukin 10 gene expression levels in fish fed the Pro-A, Pro-B, Pro-C and OTC diets were significantly greater than those of fish fed the CON and AMO diets. Intestinal histology revealed that the average villi length of fish fed the Pro-A, Pro-B, and Pro-C diets were significantly greater than that of fish fed the CON, OTC and AMO diets. The cumulative survival rates of fish fed the Pro-A, Pro-B and Pro-C diets were significantly greater than those of fish fed the CON diet after the 15th day of the challenge test. Overall, the results demonstrated that the supplementation of fish-derived bacteria, B. subtilis (1 × 108 CFU/g diet) or E. faecium (1 × 107 CFU/g diet) in the diet could be the ideal probiotics to replace antibiotics in olive flounder fed FM reduced diet.

Immunological Responses, Expression of Immune-Related Genes, and Disease Resistance of Rainbow Trout (Oncorhynchus mykiss) Fed Diets Supplied with Capsicum (Capsicum annuum) Oleoresin

A 45-day feeding study was carried out to assess the immune-stimulatory effects of capsicum oleoresin when added to rainbow trout diets. A total of 450 fish (mean weight: 155.20 ± 1.96 g) were distributed into 400 L tanks (30 fish/tank) across five experimental groups: control (CT, 0%), C7 (0.7%), C14 (1.4%), C21 (2.1%), and C28 (2.8%). Each group consisted of three replicate tanks. At the end of this period, hemato-biochemical parameters, innate immune responses, and immune-related gene expression levels were evaluated, and a histological examination of head kidney and liver sections was conducted. Finally, fish in all groups were challenged with Lactococcus garvieae and observed for an additional 20 days. The results revealed that oleoresin supplementation enhanced the immune responses of the treated fish, which was evidenced by the increased globulin, total protein, respiratory burst activity, and total immunoglobulin levels. The highest expression levels of the il-8, il-1β, TGF-β, and SAA genes was noticed in the C7 group, as compared with the results for the other groups. The IgT gene expression levels were higher in all experimental groups than in the CT group, and this increase was at the highest level in the C28 group. Following the bacterial challenge, all experimental groups displayed higher survival rates compared to that of the CT group. These values were 75.93, 72.22, 46.30, 33.33, and 29.63% in the C7, C14, C21, C28, and CT groups, respectively, with the C7 group displaying the highest survival rate among the groups. The histological examination of liver and head kidney tissues revealed that higher doses (in the C21 and C28 groups) showed an increase in cytoplasmic vacuolization, which causes adverse effects on fish health. However, the C7 group displayed normal histological structure in both tissues. Taken together, the most favorable immune responses were achieved in the C7 group, suggesting that 0.7% oleoresin could be applied to rainbow trout to boost immunity and protect the fish from diseases.

PoCXCL8, a teleost chemokine, exerts direct bactericidal, chemotactic/phagocytic, and NETs releasing properties, promoting host anti-bacterial immunity

As an important CXC chemokine, CXCL8 plays pleiotropic roles in immunological response. In teleost, CXCL8 is involved in cell migration and bacterial invasion. However, the immune antibacterial function of CXCL8 in Japanese flounder (Paralichthys olivaceus) (PoCXCL8) is largely scarce. In this research, we investigated the antibacterial property and leukocyte activation of PoCXCL8. PoCXCL8 consists of 100 amino acid residues, with a conserved chemokine CXC domain. PoCXCL8 was expressed in various tissues, with the highest level in liver and the lowest level in muscle, and sharply induced by V. harveyi or E. tarda in liver, spleen, and head kidney. In vitro, the recombinant PoCXCL8 (rPoCXCL8) could bind to Bacillus subtilis, Edwardsiella tarda, Escherichia coli, Pseudomonas fluorescens, Vibrio anguillarum, Vibrio harveyi, Staphylococcus aureus, and Micrococcus luteus, affect the growth of E. coli, E. tarda, M. luteus, and P. fluorescens, and have a direct bactericidal effect on E. coli and E. tarda. Moreover, rPoCXCL8 was able to bind the outer membranal protein rPilA of E. tarda. In addition, rPoCXCL8 could bind to PBLs, activating the PBLs activity including chemotaxis, proliferation, phagocytosis, reactive oxygen species, acid phosphatase activity. At same time, rPoCXCL8 could induce neutrophil to generate neutrophil extracellular traps (NETs) and promote the expression of inflammatory genes including IL-1β, IL6, MMP13, TNF-α, and NF-κB. In flounder, the presence of rPoCXCL8 could enhance the in vivo resistance to E. tarda in liver, spleen, and head kidney. Moreover, the PoCXCL8-deficient could attenuate the fish defense against E. tarda infection in in spleen and head kidney. In conclusion, these results provided new insights into the antibacterial properties of CXCL8 in P. olivaceus.

Bioinformatics characteristics and expression analysis of IL-8 and IL-10 in largemouth bass (Micropterus salmoides) upon Nocardia seriolae infection

IL-8 and IL-10 are crucial inflammatory cytokines that participate in defending host cells against infections. To demonstrate the function of the two interleukin genes in largemouth bass (Micropterus salmoides), we initially cloned and identified the cDNA sequences of il-8 and il-10 in largemouth bass, referred to as Msil-8 and Msil-10, respectively. The open reading frame (ORF) of Msil-8 was 324 bp in length, encoding 107 amino acids, while the ORF of Msil-10 consisted of 726 bp and encoded 241 amino acids. Furthermore, the functional domains of the SCY domain in MsIL-8 and the IL-10 family signature motif in MsIL-10 were highly conserved across vertebrates. Additionally, both MsIL-8 and MsIL-10 showed close relationships with M. dolomieu. Constitutive expression of Msil-8 and Msil-10 was observed in various tissues, with the highest level found in the head kidney. Subsequently, largemouth bass were infected with Nocardia seriolae via intraperitoneal injection to gain a further understanding of the function of these two genes. Bacterial loads were initially detected in the foregut, followed by the midgut, hindgut, and liver. The mRNA expression of Msil-8 was significantly down-regulated after infection, especially at 2 days post-infection (DPI), with a similar expression to Msil-10. In contrast, the expression of Msil-8 and Msil-10 was significantly upregulated in the foregut at 14 DPI. Taken together, these results reveal that the function of IL-8 and IL-10 was likely hindered by N. seriolae, which promoted bacterial proliferation and intercellular diffusion.

Effects of Dietary Supplement of Basil Extract on Biochemical and Immunological Parameters and Growth Performance in Oncorhynchus mykiss

Ocimum basilicum has antioxidant, anti-inflammatory, and antimicrobial effects. The present study was conducted to evaluate the effects of O. basilicum extract on growth yield, safety, and marinating physiologic functions of the rainbow trout. The fish were fed with food rations containing 0%, 1%, 2%, and 3% of basil extract. Basil extract, especially at 1% concentration food ration, significantly increased the growth parameters compared with the control group (p < 0.05). The biochemical parameters of hepatic function, renal function, glucose, triglyceride, and cholesterol level were significantly reduced in the treatment groups compared with the control group (p < 0.05). Feeding with basil extract led to a significant increase in Ig, lysozyme, and respiratory burst assay, with the most prominent elevation at 2% concentration food ration. The mucosal antibacterial activity was improved. The mortality rate after exposure to Yersinia ruckeri was lower in the treatment groups compared with the control group. The results of the present study suggest that adding 2% basil extract to the food rations of the fish may improve their physiologic function and growth yield and reinforce their immune system.

Identification, Expression and Antimicrobial Functional Analysis of Interleukin-8 (IL-8) in Response to Streptococcus iniae and Flavobacterium covae in Asian Seabass (Lates calcarifer Bloch, 1790)

In this research, the proinflammatory cytokine interleukin-8 (IL-8) was shown to play a key role in inflammatory responses in fish. This study involved the cloning of the gene that encodes IL-8 in Asian seabass (Lates calcarifer) as well as analyses of its expression and function in this fish. The expression levels of LcIL-8 indicated that it was broadly expressed in most analyzed tissues, with the most predominant expression in the whole blood 6 to 24 h after infection with S. iniae at concentrations of 105 colony-forming units (CFU)/fish (p < 0.05). After fish were immersed in F. covae, the LcIL-8 transcript was upregulated in the gills, liver and intestine, and the highest expression level was observed in the gills. However, LcIL-8 was downregulated in all the tested tissues at 48 and 96 h after infection with the two pathogenic strains, indicating that Lc-IL8 has a short half-life during the early immune responses to pathogens. Moreover, the MIC of the rLcIL-8 protein against S. iniae was 10.42 ± 3.61 µg/mL. Furthermore, functional analyses clearly demonstrated that 10 and 100 µg of the rLcIL-8 protein efficiently enhanced the phagocytic activity of Asian seabass phagocytes in vitro (p < 0.05). Additionally, in vivo injection of S. iniae following the rLcIL-8 protein indicated that 50 and 100 µg of rLc-IL-8 were highly effective in protecting fish from this pathogen (p < 0.001). The obtained results demonstrate that rLcIL-8 possesses a biological function in the defense against bacterial infections in Asian seabass.

Sexual dimorphism in NLR transcripts and its downstream signaling protein IL-1ꞵ in teleost Channa punctata (Bloch, 1793)

Nucleotide-binding oligomerization domain-like receptors (NOD-like receptors or NLRs) are a family of intracellular pattern recognition receptors (PRRs) that initiates as well as regulate inflammatory responses. NLRs are characterized by a centrally located nucleotide binding domain and a leucine rich repeat domain at the C-terminal responsible for the recognition of intracellular microbe-associated molecular patterns (MAMPs) and danger-associated molecular patterns (DAMPs). In the present study in adult spotted snakehead we have investigated the sex-dependent tissue distribution of NLRs known to be associated with inflammation in teleost namely NOD1, NOD2, NLRC3, NLRC5, and NLRX1. Further, the sexual dimorphism in the expression of NLR transcript as well as the pro-inflammatory protein IL-1β was explored in fish under normal conditions, and in fish exposed to bacterial lipopolysaccharide (LPS). The NLRs show ubiquitous and constitutive expression in all the tissues. Moreover, a prominent disparity between males and females was observed in the basal expression of these genes in various tissues. The sexual dimorphism in NLR expression was also prominent when fish were exposed to LPS. Similarly, IL-1β exhibited sexual dimorphism in both normal as well as LPS-exposed fish.

Characterization and function of Japanese flounder (Paralichthys olivaceus) slc2a6 in response to lymphocystis disease virus infection

Slc2a6 is a member of the slc2 family (solute carrier 2 family) and previous reports have indicated its involvement in the inflammatory response. Slc2a6 is regulated by the NF-ĸB signaling pathway. This study investigated the differential expression of slc2a6 in the early embryonic development of Japanese flounder, revealing that the early gastrula stage had the highest level of slc2a6 expression. Moreover, slc2a6 expression was increased in vitro after stimulation by lymphocystis disease virus (LCDV), and in vivo experiments also showed significantly elevated levels in the spleen and muscle tissues following LCDV stimulation. Subcellular localization revealed that Slc2a6 was expressed in both the nucleus and cytoplasm of cells. The pcDNA3.1-slc2a6 overexpression plasmid was successfully constructed; the si-slc2a6 interfering strand was screened and samples were collected. The expression of NF-ĸB signaling pathway-related genes il-1β, il-6, nf-ĸb, and tnf-α was evaluated in overexpressed, silenced, and LCDV-stimulated samples. The results showed that slc2a6 is involved in viral regulation in Japanese flounder by regulating innate immune responses.

Oral bovine serum albumin administration alleviates inflammatory signals and improves antioxidant capacity and immune response under thioacetamide stress in blunt snout bream fed a high-calorie diet

This investigation looks at the impact of oral bovine serum albumin (BSA) on antioxidants, immune responses, and inflammation signals in blunt snout bream fed a high-calorie diet. 480 fish (average weight: 45.84 ± 0.07 g) were randomly fed a control diet, a high-fat diet (HFD), a high carbohydrate diet (HCD), and a high-energy diet (HED) in six replicates for 12 weeks. After the feeding trial, fish were orally administered with 10% BSA for 10 h, then blood and liver samples from five fish were randomly obtained after 10 h to determine plasma inflammatory markers and inorganic components. Also, the leftover fish were injected with thioacetamide, blood and liver samples were simultaneously obtained at 12, 48, and 96 h, respectively, to determine antioxidant, immune, and inflammatory signals, with survival rates recorded at the same time interval. After 10 h, plasma inflammatory markers such as tumour necrosis factors (TNF-α), interleukin 6 (IL6), nitric oxide (NO), Monocyte chemoattractant protein-1(MCP-1), and cortisol were significantly improved in fish fed HCD and HED as compared to the control. After thioacetamide stress, plasma lysozyme (LYM), complement 3, myeloperoxidase (MPO), and alkaline phosphatase activities, as well as immunoglobulin M, levels all increased significantly (P < 0.05) with increasing time with maximum value attained at 96 h, but shows no difference among dietary treatment. Similar results were observed in liver superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) activities and malondialdehyde (MDA) content, but tended to reduce at 96 h. nf-kb, tnf-α, and mcp-1 tend to decrease with the minimum value attained at 48 h and gradually decrease with increasing time at 96 h. After 96 h of the thioacetamide (TAA) challenge, the survival rate of blunt snout bream fed with an HFD and HCD was significantly lower (P < 0.05) at 48, and 96 h before the administration of BSA. However, no differences were observed among dietary treatments after the BSA administration. Overall, this study indicated that oral dietary administration of BSA might greatly enhance the antioxidant capability and innate immunity and mitigates inflammation signals after TAA stress in blunt snout bream fed high energy diet.

Host-pathogen interaction unveiled by immune, oxidative stress, and cytokine expression analysis to experimental Saprolegnia parasitica infection in Nile tilapia

The present study evaluated the pathogenicity, immunological, and oxidant/antioxidant responses against Saprolegnia parasitica (S. parasitica) infection in Nile tilapia (Oreochromis niloticus). Three groups of Nile tilapia were assigned as the control group (no zoospores exposure). The other two groups were challenged by Saprolegnia zoospores; one was used for sampling, and the other for mortality monitoring. The study lasted 3 weeks and was sampled at three point times at 1, 2, and 3 weeks. Results showed that S. parasitica zoospores were pathogenic to Nile tilapia, causing a cumulative mortality rate of 86.6%. Immunoglobulin M and C- reactive protein (IgM and CRP) levels showed a similar trend being significantly (P < 0.05, P < 0.001) higher in the infected group at weeks 1, 2, and 3, respectively, compared to the control group. Oxidant and antioxidant parameters in gills revealed that Malondialdehyde (MDA) level was significantly higher in the infected group compared to the control group. While catalase, glutathione peroxidase, and superoxide dismutase (CAT, GSH, and SOD) levels were significantly decreased in the infected group compared to the control group. Compared to the control, the tumor necrosis factor-α (TNF-α) gene was firmly upregulated in gill tissue at all-time points, particularly at day 14 post-infection. Meanwhile, Interleukin 1-β (IL-1 β) gene was significantly upregulated only at days 7 and 14 post-infection compared to control. Histopathological examination revealed destructive and degenerative changes in both skin and gills of experimentally infected Nile tilapia. Our findings suggest that Nile tilapia-S. parasitica infection model was successful in better understanding of pathogenicity and host (fish)-pathogen (oomycete) interactions, where the induced oxidative stress and upregulation of particular immune biomarkers in response to S. parasitica infection may play a crucial role in fish defense against oomycetes in fish.

Identification and functional characterization of caspases in turbot (Scophthalmus maximus) in response to bacterial infection

Apoptosis is the autonomous and orderly death of cells under genetic control to maintain the stability of the internal environment, and is a programmed cell death process with unique morphological and biochemical properties that is regulated by a variety of factors. Caspase gene family has a significant function in the process of apoptosis. However, the knowledge of caspases in turbot remains largely unknown. In present study, a total of nine turbot caspase genes were identified. The mRNA length of these caspase genes was ranged from 1149 bp (caspase-1) to 3216 bp (caspase-2), and the protein length was ranged from 281 aa (caspase-3a) to 507 aa (caspase-10). Phylogenetic analysis showed these caspase genes were divided into three subfamilies. The qRT-PCR results showed that turbot caspase genes were expressed in all the examined organs, especially the intestine, kidney, blood and gills. Meanwhile, we explored the expression patterns of caspase genes in the intestine, skin and gills after Vibrio anguillarum and Aeromonas salmonids infections. The results showed that caspase genes showed different expression patterns in mucosal tissues after bacterial infection, demonstrating the critical role of caspase genes in mucosal immune responses. In addition, protein-protein interaction analysis showed that caspase proteins interacted with immune molecules such as NLR, IL-1β, and birc. The results of interference and overexpression experiments showed that caspase-1 might play key roles in the regulation of the IL-1β production, but the detailed mechanism needs to be further studied. The results of this study provide valuable information for further study the roles of caspase genes in turbot, which could help us to further understand the inflammatory pathways in teleost.

Modulation of Immune-Related Gene Expressions in Zebrafish (Danio rerio) by Dietary Purslane (Portulaca oleracea) Extract

To promote fish's immunity against pathogens in the aquaculture industry, fish dietary fortification with additives or compounds has increasingly attracted attention. In the present study, zebrafish (Danio rerio) was used as an animal model to investigate the effects of purslane, Portulaca oleracea, extract (PE) on the relative expression level of some immune-related genes. A total of 300 zebrafish were randomly divided into four treatment groups and fed for 8 weeks with the basal diets supplemented with 0.5, 1, 1.5, and 2% of PE. The control group was fed with a basal diet without PE. At the end of 8 weeks, the mRNA expression levels of interleukin 1-beta (IL-1β), interleukin 10 (IL-10), transforming growth factor-beta (TGF-β), tumor necrosis factor-alpha (TNF-α), superoxide dismutase (SOD), and lysozyme (LYZ) in the fish were evaluated. The results showed that the mRNA expression level of IL-1β was significantly upregulated in the fish fed with 1 and 2% PE compared to the control group (p < 0.05). Moreover, the evaluation of the mRNA expression level of TGF-β was significantly increased in a dose-dependent manner in the 1.5 and 2% fed groups compared to the control group (p < 0.05). However, the IL-10 was significantly downregulated in all treated groups compared to the control group (p < 0.05). The expression of the TNF-α gene was not affected amongst all groups by the inclusion of PE in the zebrafish diet (p > 0.05). Based on the results, the diet supplemented with 1.5 and 2% PE significantly upregulated the mRNA expression levels of LYZ and SOD, respectively, compared to the control group (p < 0.05). In conclusion, dietary inclusion of PE may result in beneficial effects on some immune responses via upregulation of some immune genes in zebrafish.

Red sea bream interleukin (IL)-1β and IL-8 expression, subcellular localization, and antiviral activity against red sea bream iridovirus (RSIV)

Interleukin-1 beta (IL-1β) is transcribed by monocytes, macrophages, and dendritic cells in response to activation of toll-like receptors (TLRs) by pathogen-associated molecular patterns (PAMPs) or cytokine signalling and causes a rapid inflammatory response to infection. IL-8, also known as chemokine C-X-C motif ligand (CXCL)-8, is regulated by IL-1β and affects the chemotaxis of macrophages and neutrophils upon pathogen infection. In healthy red sea bream, rsbIL-1β is most highly distributed in the liver, and rsbIL-8 is most highly distributed in the head kidney. In response to RSIV infection, rsbIL-1β and rsbIL-8 mRNA are significantly upregulated in the kidney and spleen. This may be because the primary infection targets of RSIV are the kidney and spleen. In the gills, both genes were significantly upregulated at 7 days after RSIV infection and may be accompanied by a cytokine storm. In the liver, both genes were significantly downregulated at most observation points, which may be because the immune cells such as macrophages and dendritic cells expressing rsbIL-1β or rsbIL-8 migrated to other tissues because the degree of RSIV infection was relatively low. Using a GFP fusion protein, it was confirmed that rsbIL-1β and rsbIL-8 were localized to the cytoplasm of Pagrus major fin (PMF) cells. RsbIL-1β overexpression induced the expression of interferon gamma (IFN-γ), myxovirus-resistance protein (Mx) 1, IL-8, IL-10, TNF-α, and MyD88, while rsbIL-8 overexpression induced the expression of IFN-γ, Mx1, rsbIL-1β and TNF-α. In addition, overexpression of both genes significantly reduced the genome copies of RSIV and significantly reduced the viral titers. Therefore, rsbIL-1β and rsbIL-8 in red sea bream play an antiviral role against RSIV through their normal signalling.

Effects of dietary Astragalus caudiculosus (Boiss & Huet, 1856) supplementation on growth, hematology, antioxidant enzyme activities, and immune responses in rainbow trout (Oncorhynchus mykiss Walbaum, 1792)

The potential dietary utilization of Astragalus caudiculosus (AC) in rainbow trout (Oncorhynchus mykiss) was investigated. Four different fish groups (control, AC1, AC2.5, and AC5) were assigned and received the AC-containing diet for 90 days at the rates of 0, 1, 2.5, and 5%, respectively. Results indicated that the growth performance of the AC supplemented fish improved significantly (P < 0.05). Among non-specific immune parameters examined, while lysozyme activity of the AC supplemented fish increased (P < 0.05), oxidative radical production decreased in AC1 and AC2.5 fish groups (P < 0.05) but did not differ in the AC5 group (P > 0.05) compared to the control. Moreover, myeloperoxidase activity was not affected by the AC supplementation (P > 0.05). All pro-inflammatory and anti-inflammatory cytokine gene expressions, except IL-1β, were up-regulated, especially in the fish groups fed with 2.5 and 5% AC supplemented feed (P < 0.05). AC administration caused an elevation in GPx and G6PDH activities, and a decrease in SOD, CAT, and lipid peroxidation (P < 0.05). Overall, AC extract was found to improve the growth, antioxidant status, and immune response of the fish.

Insights into the functional role of grass carp IL-8 in head kidney leukocytes: pro-inflammatory effects and signalling mechanisms

Interleukin-8 (IL-8) is a critical chemokine regulating immune cells' chemotaxis as well as their physiological or pathological activations. In fish cells, recombinant IL-8 proteins induced transcriptions of pro-inflammatory cytokines. Nonetheless, the exact mechanisms underlying the function of fish IL-8 as a pro-inflammatory cytokine are still unclear. In this paper, the authors first prepared recombinant grass carp IL-8 (rgcIL-8) using an Escherichia coli expression system, and later confirmed rgcIL-8 increased gene expression of il8, il1β and tumour necrosis factor alpha (tnfα) in grass carp head kidney leukocytes (HKLs). Using signalling pathway inhibitors, the authors showed that rgcIL-8 regulated transcriptions of pro-inflammatory cytokines via MAPK and/or NF-κB signalling pathways. They cloned gcIL-8-specific receptor CXCR1 and subsequently discovered that gcIL-8 could increase the activity of NF-κB and the transcription of IL-1β via CXCR1. Simultaneously, antibody neutralization assay showed that endogenous IL-8 is partially relevant to the self-regulation of IL-1β. Moreover, rgcIL-8 led to the expression of inducible nitric oxide synthase gene, causing an accumulation of nitric oxide in the culture medium of HKLs, suggesting the potential of gcIL-8 to mediate inflammatory response. This study not only enriched the function of IL-8 in teleost but also revealed it as a potential target for the inflammatory control in grass carp.

Effects of dietary xylooligosaccharide prebiotic supplementation on growth, antioxidant and intestinal immune-related genes expression in common carp Cyprinus carpio fed a high-fat diet

This study investigated the effects of xylooligosaccharide (XOS) supplementation on growth, intestinal enzyme, antioxidant and immune-related genes in common carp Cyprinus carpio fed a high-fat diet (HFD). One hundred and ninety two fish with an initial weight of 19.61 ± 0.96 g were allocated into 24 tanks (eight fish per tank in four replicate) and were fed the control diet, HFD, HFD with 0.5%, 1%, 2% and 3% XOS supplementation. From the result, fish offered HFD with 1% XOS supplementation significantly obtained a higher body mass index and feed efficiency ratio, whereas condition factor was higher in fish fed HFD supplemented with 2% XOS but no difference was attributed to other supplemented group compared to control group. Also, fish fed HFD supplemented with 1%-2% XOS significantly improved protease, lipase, creatine kinase and sodium/potassium ATPase activities compared to other groups. Fish offered HFD were significantly lower in superoxide dismutase (SOD), catalase, glutathione peroxidase (GPX), myeloperoxidase, acid phosphatase, lysozyme activities and immunoglobulin content, but the opposite result was found for aspartate transaminase, alanine transaminase activities, malondialdehyde, protein carbonyl and cortisol content as compared with the control. However, this effect was reversed with HFD supplemented with XOS. Also, interleukin 1β, interleukin 8, tumour necrosis factors, interferons, caspase-3 and caspase-9 in the intestine were all up-regulated in the HFD group, while the reverse pattern was found in SOD, GPX, lysozyme-C, complement 3 and mucin 5b (muc5b), than the control group. These effects were all enhanced by feeding the XOS diet, especially those fed 1%-3% supplementation. In conclusion, XOS inclusion can improve the growth, digestive enzymes, antioxidants and immune response of common carp fed HFD.

Molecular identification of Klebsiella pneumoniae and expression of immune genes in infected spotted gar Lepisosteus oculatus

Spotted gar (Lepisosteus oculatus) is a primitive ray-finned fish which has not undergone the third round whole genome duplication and commonly used as a model to study the evolution of immune genes. In this study, a pathogenic strain of Klebsiella pneumoniae (termed KPY01) was isolated from a diseased spotted gar, based on the Gram-stain and phylogenetic analysis of the 16S rDNA and khe genes. Further, the virulence genes and drug resistance genes were determined and drug sensitivity tests were performed to explore the virulence and drug resistance of the KPY01. Putative biosynthetic gene clusters (BGCs) for the biosynthesis of secondary metabolites were predicted using the anti-SMASH5.0 online genome mining platform. Histopathological analysis revealed that the immune cells were significantly decreased in the white pulp of spleen of fish infected with K. pneumonia and tissue inflammation became apparent. Besides, the expression of cytokines including interleukin (il) -8, il-10, il-12a, il-18 and interferon γ (ifn-γ) were shown to be modulated in the spleen, gills and kidney. Our work provides useful information for further investigation on the virulence of K. pneumoniae and host immune responses to K. pneumoniae infection in fish.

An IL-1β homologue induced inflammation and antibacterial immune defense in Siberian sturgeon (Acipenser baeri)

Interleukin-1β is a key pro-inflammatory cytokine functioning in initiation of inflammatory responses against bacterial- and viral-infections. In the present study, a putative IL-1β counterpart was identified from Siberian sturgeon (Acipenser baeri) and designated as AbIL-1β. The Abil-1β cDNA sequence consists of 1130 bp with an open reading frame (ORF) of 585 bp, which encodes a 194 amino acid (aa) protein. Multiple amino acid sequence alignment revealed that a possible mature peptide could start at Leu¹⁸, although no cut site for ICE (IL-1β converting enzyme) enzyme was present in Siberian sturgeon IL-1β. Even if AbIL-1β shares a relative low identity (33.6%) with another sturgeon type II IL-1β gene from Acipenser dabryanus, they still clustered together in phylogenetic tree. Endogenous Abil-1β was highly expressed in brain, blood, head kidney and spleen of healthy Siberian sturgeon, and remarkably up regulated in head kidney, spleen, and liver upon Aeromonas hydrophila (A.h) challenge. Consistently, in vitro stimulation test using heat-killed A.h and LPS significantly increased Abil-1β transcripts of primary spleen cells. To investigate the bactericidal capability of AbIL-1β, recombinant AbIL-1β (rAbIL-1β) was generated by prokaryotes. Pre-injection of rAbIL-1β reduced the bacterial load in sturgeon spleen after A.h infection. Further, rAbIL-1β was served as feed additive and demonstrated to enhance hybrid sturgeon's defense against A.h infection by increased expressional levels of immune-related genes (IL-1β, IL-6, IL-8, IgM and MHCIIβ), elevated activities of serum lysosome, ACH50, and MPO, as well as higher percent survival. In summary, the current results suggested that AbIL-1β functions in immune regulation and could improve sturgeon's resistance to bacterial infection.

Molecular characterization and biological function of CXCR1 in Nocardia seriolae-infected largemouth bass (Micropterus salmoides)

Interleukin-8 (IL-8, CXCL8), a pro-inflammatory chemokine secreted by a variety of cell types, plays a critical role in the development of various immune diseases. Interactions between IL-8 and its receptor CXC receptor 1/2 (CXCR1/2) are known to promote chemotaxis and phagocytosis in many immune responses. In this study, we report the molecular characteristics and pharmacological activity of CXCR1 (MsCXCR1) in largemouth bass (Micropterus salmoides) and evaluated the functional involvement of MsCXCR1 in individuals infected with the pathogen Nocardia seriolae. MsCXCR1 was cloned into the pEGFP-N1 plasmid and the subcellular localization of MsCXCR1 on the cell membrane was verified in MsCXCR1-EGFP-expressing HEK293 cells. Following observation of receptor internalization and intracellular signaling detection, we further determined the functional interaction of secreted interleukin-8 (LcIL-8, the ligand for CXCR1 in large yellow croaker) and MsCXCR1 was further determined, and the ERK phosphorylation signal activation mediated by MsCXCR1 was demonstrated. Quantitative real-time PCR assays were conducted to analyze the transcriptional distribution of MsCXCR1 in various tissues of healthy and diseased largemouth bass. These results illustrate the significant elevation of MsCXCR1 expression in the head kidney, spleen and liver of M. salmoides, suggesting that MsCXCR1 was involved in the immune response in N. seriolae-infected largemouth bass and potentially affects the digestive function of this species.

Nano spirulina dietary supplementation augments growth, antioxidative and immunological reactions, digestion, and protection of Nile tilapia, Oreochromis niloticus, against Aeromonas veronii and some physical stressors

The current study evaluated the effects of nano delivery of Spirulina platensis on growth performance, digestive enzymes, and biochemical, immunological, and antioxidative status, as well as resistance to Aeromonas veronii and some physical stressor challenges in Nile tilapia, Oreochromis niloticus. Three experimental fish groups (n = 270) with mean weights of 26 ± 0.30 g and mean lengths of 10 ± 0.5 cm were used; the first additive-free basal diet served as the control group, whereas the following two groups were supplemented with spirulina nanoparticles (SPNP) at 0 (control), 0.25, and 0.5%/kg diet for 4 weeks. Following the feeding trial, fish were challenged with hypoxia, cold stresses, and pathogenic bacteria (A. veronii) infection (9 × 10⁸ CFU/ml). SPNP supplementation, especially 0.5%, (p < 0.05) significantly increased growth performance (specific growth rate % day^-1, feed conversion ratio, and length gain rate %), immunological (plasma lysozyme and liver nitrous oxide) antioxidants (superoxide dismutase, catalase, and glutathione peroxidase in liver), biochemical (aspartate aminotransferase, alanine transaminase, glucose, and cortisol concentrations in plasma) assays, and digestive enzymes (lipase and amylase in plasma). The expression of liver's heat shock protein 70 (HSP70) and interleukin 1, beta (IL-1β) genes showed a significant upregulation outline of 0.5% SPNP > 0.25% SPNP > 0% SPNP compared with the control. Protection in the incorporated fish groups exposed to A. veronii was 100% compared with the control group, which showed 50% cumulative mortalities. In conclusion, dietary SPNP supplementation improved growth performance, antioxidant activity, immune response, digestive enzymes, related gene expression, and resistance of Nile Tilapia to hypoxia, cold, and A. veronii infection. Thus, SPNP could be used as a natural therapy for controlling those stressors.

Molecular characterization and gene expression analysis of the pro-inflammatory cytokines IL-1β and IL-8 in the South American fish Piaractus mesopotamicus challenged with Aeromonas dhakensis

In the present study, the complete characterization of cDNA and genomic sequences of IL-1β and IL-8, as well as the expression profile of these genes in the South American fish pacu (Piaractus mesopotamicus) is provided. The full-length pmIL-1β cDNA was composed of 1208 nucleotides that would produce a precursor peptide with 273 amino acid residues. A putative caspase-1 cleavage site, similar to what is found in mammalian IL-1β, was identified producing a mature peptide with a theoretical molecular weight of 17.21 kDa. The pmIL-8 cDNA sequence consisted of 1019 nucleotides which encoded a 95-amino acid protein with a theoretical molecular weight of 10.43 kDa that showed all typical CXC chemokine features, including a 20-residue signal peptide and four conserved cysteine residues. Constitutive mRNA expression was detected for both genes in the liver, head kidney, gill, intestine, skin and spleen. After a bacterial challenge, up-regulation was detected for both pmIL-1β and pmIL-8 in the spleen and head kidney at 12 h post-infection. At 24 h post-infection there was a decrease in the expression of both genes, with pmIL-8 showing a significant down-regulation in the liver and head kidney when compared to the control groups.

Comparative Characterization of Two cxcl8 Homologs in Oplegnathus fasciatus: Genomic, Transcriptional and Functional Analyses

CXCL8 (interleukin-8, IL-8) is a CXC family chemokine that recruits specific target cells and mediates inflammation and wound healing. This study reports the identification and characterization of two cxcl8 homologs from rock bream, Oplegnathus fasciatus. Investigation of molecular signature, homology, phylogeny, and gene structure suggested that they belonged to lineages 1 (L1) and 3 (L3), and designated Ofcxcl8-L1 and Ofcxcl8-L3. While Ofcxcl8-L1 and Ofcxcl8-L3 revealed quadripartite and tripartite organization, in place of the mammalian ELR (Glu-Leu-Arg) motif, their peptides harbored EMH (Glu-Met-His) and NSH (Asn-Ser-His) motifs, respectively. Transcripts of Ofcxcl8s were constitutively detected by Quantitative Real-Time PCR (qPCR) in 11 tissues examined, however, at different levels. Ofcxcl8-L1 transcript robustly responded to treatments with stimulants, such as flagellin, concanavalin A, lipopolysaccharide, and poly(I:C), and pathogens, including Edwardsiella tarda, Streptococcus iniae, and rock bream iridovirus, when compared with Ofcxcl8-L3 mRNA. The differences in the putative promoter features may partly explain the differential transcriptional modulation of Ofcxcl8s. Purified recombinant OfCXCL8 (rOfCXCL8) proteins were used in in vitro chemotaxis and proliferation assays. Despite the lack of ELR motif, both rOfCXCL8s exhibited leukocyte chemotactic and proliferative functions, where the potency of rOfCXCL8-L1 was robust and significant compared to that of rOfCXCL8-L3. The results, taken together, are indicative of the crucial importance of Ofcxcl8s in inflammatory responses and immunoregulatory roles in rock bream immunity.

Molecular Characterization and Chemotactic Function of CXCL8 in Northeast Chinese Lamprey (Lethenteron morii)

Chemokine-induced chemotaxis of leukocytes is an important part of the innate immunity and has been shown to mediate inflammation in all groups of jawed vertebrates. For jawless vertebrates, hagfish leukocytes are known to show chemotaxis toward mammalian complement anaphylotoxin and Gram-negative bacteria lipopolysaccharide. However, whether chemokines mediate chemotaxis of leukocytes in jawless vertebrates has not been conclusively examined. Here, we show C-X-C motif chemokine ligand 8 (CXCL8, also named interleukin 8) of the Northeast Chinese lamprey (Lethenteron morii) (designated as LmCXCL8) induces chemotaxis in its leukocytes. We identified LmCXCL8 and found it possesses the characteristic N-terminal cysteine residues and GGR (Gly-Gly-Arg) motif. The Lmcxcl8 gene was found to be expressed in all examined tissues, and its expression was inducible in the lamprey challenged by an infectious bacterium, Pseudomonas aeruginosa. A recombinant LmCXCL8 protein elicited concentration-dependent chemotaxis in peripheral blood leukocytes isolated from the Northeast Chinese lamprey. Based on these results, we conclude that LmCXCL8 is a constitutive and inducible acute-phase cytokine that mediates immune defense and trace the chemotactic function of chemokine to basal vertebrates.

Dietary supplementation with Lactobacillus acidophilus enhanced the growth, gut morphometry, antioxidant capacity, and the immune response in juveniles of the common carp, Cyprinus carpio

This study investigated the effect of Lactobacillus acidophilus-fortified diets on growth performance, antioxidant profiles, and immunity-related gene expressions of common carp, Cyprinus carpio juveniles. Four isonitrogenous diets containing 0, 10², 10⁴, or 10⁶ cfu/mL/kg L. acidophilus were fed to 240 Cyprinus carpio juveniles (mean = 21.34 ± 1.85 g), allotted to 12 rectangular tanks in a completely randomized designed at 3% body weight for 56 days. Growth performance and nutrient utilization were evaluated using standard procedures. Intestinal villi were measured, antioxidant profiles were evaluated from blood sera, and immunity-related gene expressions were evaluated. The results revealed that fish fed dietary 10⁶ had significantly higher weight gain, SGR, feed intake, and lower FCR. Also, villi length, width, and areas of absorption were significantly improved in a dose-dependent manner. Furthermore, innate immune profiles, superoxide dismutase, catalase, respiratory bust activity as well as transforming growth factor beta (TGFβ), interleukin 8 (IL-8), and tumor necrosis factor alpha (TNF-alpha) were significantly stimulated. This study evoked that Lactobacillus acidophilus supplementation enhanced better growth performance, improved antioxidant profiles, and modulated expression of immune-related genes of common carp, Cyprinus carpio, than the fish fed control diet. Results show that fish fed fortified diets had better growth performance, improved antioxidant profiles, and modulated expression of immune-related genes.

Molecular Identification and Dual Functions of Two Different CXC Chemokines in Nile Tilapia (Oreochromis niloticus) against Streptococcus agalactiae and Flavobacterium columnare

Two CXC chemokines in Nile tilapia (On-CXC1 and On-CXC2) were identified at both the genomic and proteomic levels. A southern blot analysis and comparison searching in Ensembl confirmed the typical structure of the CXC chemokine genes and provided evidence for unusual mechanisms used to generate the two different CXC chemokine transcripts that have not been reported in other vertebrate species so far. The expression levels of On-CXC1 and On-CXC2 were analyzed by quantitative real-time PCR. These two mRNAs were detected in various tissues of normal Nile tilapia, especially in the spleen, heart, and head kidney, indicating a homeostatic function in immunosurveillance. A time-course experiment clearly demonstrated that these two transcripts were effectively enhanced in the head kidney, spleen and trunk kidney of Nile tilapia 6, 12 and 24 h after injection with Streptococcus agalactiae but were down-regulated in all tested tissues at 48 h, reflecting the fact that they have short half-lives during the crucial response to pathogens that is characteristic of CXC chemokine genes in other vertebrates. Functional analyses obviously exhibited that these two CXC chemokines at concentrations of 1–10 μg strongly inactivated S. agalactiae and Flavobacterium columnare and effectively induced phagocytosis of leukocytes in vitro.

The effects of dietary yeast hydrolysate on growth, hematology, antioxidant enzyme activities and non-specific immunity of juvenile Nile tilapia, Oreochromis niloticus

The present study was aimed to compare and evaluate the impacts of supplemented diets with different yeast hydrolysate (YH) levels on growth performance, body composition, hematological characteristics, antioxidant enzyme activities, and non-specific immunity (intestinal cytokines) of juvenile Nile tilapia (Oreochromis niloticus). Three isonitrogenous (protein, 33%) and isolipidic (lipid, 6%) experimental diets supplemented graded levels of YH (0% for control; 1% and 3% as tested diets) were fed to juvenile Nile tilapia. A total of 240 fish with initial body weight averaging 3.5 ± 0.02 g were randomly divided into three groups with four replicates per group and 20 fish for each replicate. For apparent satiation, the fish were fed twice daily during eight weeks. The results showed no significant difference in survival among all treatments. The fish fed the diet containing 1% yeast hydrolysate had significantly elevated weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER) compared to the control group and lower feed conversion ratio (FCR). The fish fed 1% and 3% YH showed higher glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT) activity and a significantly lower malondialdehyde (MDA) level in the liver than the control group, indicating enhancement of the anti-oxidant status. Serum lysozyme activity was significantly increased in the diet having 1% and 3% yeast hydrolysate supplementation groups, suggesting an improvement influence on the non-specific immune response. The expression of IL-1β, IL-10, TNF-α, TGF-β2, ALP and TLR2 was significantly elevated in fish fed the diet containing 1% YH. In conclusion, dietary supplementation with 1% yeast hydrolysate improves growth performance, and feed utilization enhances the antioxidant status and exerts an adequate stimulus on the non-specific immunity (intestinal cytokines) of Nile tilapia.

Humoral and skin mucosal immune parameters, intestinal immune related genes expression and antioxidant defense in rainbow trout (Oncorhynchus mykiss) fed olive (Olea europea L.) waste

A six-week feeding trial was carried out to evaluate the effects of inclusion of dietary olive waste cake (OWC, 0, 0.5, 2.5 and 5 g kg^-1 diet) on performance, antioxidant condition and immune responses of rainbow trout (Oncorhynchus mykiss) (2.5 ± 0.1 g). Supplementing diet with 2.5 and 5 g OWC kg^-1 diet significantly enhanced serum and mucosal lysozyme activity in fish. Regarding mucosal immunity, fish fed 2.5 and 5 g OWC kg^-1 diets had higher skin mucus total Ig concentrations than other groups. In relation to antioxidant status, those in 2.5 g OWC kg^-1 and the control groups exhibited the highest and the least liver superoxide dismutase and glutathione peroxidase activities, respectively. Furthermore, the activity of liver glutathione S transferase in fish fed 2.5 and 5 g OWC kg^-1 diets was higher than the other treatments. In respect to gut cytokines gene expression, our findings demonstrated dietary OWC did not influence interlukines-1β and 10 genes expression, but relative expression of IL8 gene gradually up-regulated with increasing dietary OWC level. Moreover, fish fed 0.5 g OWC kg^-1 and the control diets had the highest and the lowest gut tumor necrosis factor-α gene expression values, respectively. The relative expression of transforming growth factor-β significantly down-regulated in gut of fish fed 2.5 and 5 g OWC kg^-1 diets compared to other groups. Supplementing diet with OWC pronouncedly improved growth and feed conversion ratio in fish compared to the control. Overall, the findings of this study suggested that inclusion of 2.5 g OWC kg^-1 diet can improve growth rate, oxidative stress status, humoral and skin mucosal immune responses in O. mykiss fingerlings and it can be considered as a functional feed additive for this species.

Hematological and immune genes responses in yellow catfish (Pelteobagrus fulvidraco) with septicemia induced by Edwardsiella ictaluri

Yellow catfish (Pelteobagrus fulvidraco) has been an economically important freshwater species in China because of its good meat quality. In present, the high-density breeding industry has suffered great damage from bacterial infections, in especial, the rapid illness and death of fish caused by bacterial septicemia leads to huge economic losses. Therefore, it is urgent and important to identify pathogenic bacteria and study its pathogenicity. In this study, we isolated a bacterial strain from the yellow catfish with typical septicemia and named it E. 719, then, by morphological observations, regression infection, biochemical identification, 16S rDNA sequence analysis and triple PCR identification, E. 719 was determined to be Edwardsiella ictaluri. Further, we infected yellow catfish with E. ictaluri to study its effects on mortality rate, hematological, histopathological disturbances and expression of immune genes. The mortality results showed that E. ictaluri was highly pathogenic, all infected fish died after 14 days post injection, and the distribution of bacteria in body kidney, spleen, liver, head kidney and brain of fish was continuously detected by measuring the amount of bacteria in the tissues. In addition, the number of red blood cells decreased significantly with the time of infection, while the number of white blood cells and thrombocytes increased. In particular, the number of monocytes and neutrophils increased significantly in the differential leucocyte count (DLC). Histopathologic changes observed by HE staining showed similar results, gill, intestine, spleen and head kidney showed obvious inflammation, bleeding and necrosis. Besides, checking by real time quantitative RT-PCR assays, in both spleen and head kidney tissues which were the major immune organs, mRNA expressions of immune gene IL-1β, TNF-α, and MR significantly increased in the early and middle stages of infection, which suggested that the infection of E. ictaluri caused a strong immune response in yellow catfish. This study provides a preliminary basis for the diagnosis and treatment of pathophysiology septicemia in yellow catfish induced by E. ictaluri.

Effects of dietary yeast hydrolysate on the growth, antioxidant response, immune response and disease resistance of largemouth bass (Micropterus salmoides)

A 56-day growth trial was conducted to investigate the effects of dietary yeast hydrolysate on the growth performance, antioxidation, immune response and resistance against Aeromonas hydrophila in largemouth bass. Four experimental diets were prepared with yeast hydrolysate levels of 0% (Y0), 1.5% (Y1.5), 3.0% (Y3.0) and 4.5% (Y4.5). Each diet was randomly assigned to triplicate 150-L tanks and each tank was stocked with 30 largemouth bass (initial body weight, IBW = 7.71 ± 0.02 g). A challenge test was carried out after the feeding trial by injecting A. hydrophila intraperitoneally for 4-day observation. The results showed that the FBW and WGR in Y1.5 group were significantly higher than those in Y0 group (P < 0.05) and the feed conversion ratio (FCR) got the lowest value in Y1.5 group. And the hydrolysate supplement significantly increased the 4-day cumulative survival rate after the bacterial challenge (P < 0.05). The plasma malondialdehyde was lower in the yeast hydrolysate supplement groups in both pre- and post-challenge test (P < 0.05), while the plasma C3 increased (P < 0.05). In post-challenge test, the plasma superoxide dismutase (SOD) and catalase (CAT) activities increased in the Y1.5 and Y3.0 groups respectively (P < 0.05), and plasma lysozyme in Y1.5 group and the plasma IgM in Y3.0 group were higher than those in others respectively (P < 0.05). For the q-PCR results, in post-challenge test, the hepatic hep2 expression level in Y1.5 and Y4.5 groups were both significantly higher than those in others (P < 0.05), as well as il-8 in Y3.0 group. The spleen hif-1alpha and tgf-beta1 expression levels in Y4.5 group were all significantly lower than those in others (P < 0.05), while the gilt was significantly higher (P < 0.05) in the post-challenge test. And the expression levels of spleen tnf-alpah1 in Y1.5 and Y3.0 groups and il-8 in Y3.0 group were all significantly higher than those in other groups (P < 0.05) in the post-challenge test. The head kidney gilt expression level was significantly higher in the yeast hydrolysate supplement groups compared with the Y0 group (P < 0.05), and the head kidney il-8 expression level in Y1.5 group was significant higher than those in other groups in post-challenge test (P < 0.05). The present results indicated dietary yeast hydrolysate improved the antioxidant ability and enhanced the immune response of largemouth bass without negative effect on growth. And 1.5% or 3.0% of dietary yeast hydrolysate was recommended for largemouth bass based on the present results.

Interleukin-8 (IL-8) Expression in the Olive Flounder (Paralichthys olivaceus) against Viral Hemorrhagic Septicemia Virus (VHSV) Challenge

Interleukin-8 (IL-8) is an inflammatory cytokine that plays an important role in the inflammatory response through the activation of neutrophil cells. The expression of IL-8 was investigated in early developmental stages of the olive flounder and in tissues of 8-month-old individuals. The expression of IL-8 increased after the initiation of the immune system rather than at the early stage of development, and high expression was observed in the gills and spleen, the organs associated with immunity and metabolism. In addition, IL-8 expression after infection by viral hemorrhagic septicemia virus significantly increased in the fin, gill, muscles, and spleen. These results suggest that IL-8 is closely related to inflammation and immune regulation in the immune response of the olive flounder and may be used as a basis for studies on the immune systems of other fish.

Unraveling the evolutionary origin of ELR motif using fish CXC chemokine CXCL8

Chemokines are chemotactic proteins involved in host defense through the migration of immune-regulatory cells to the site of infection. Interleukin-8 (CXCL8/IL8) is the most studied "ELR-CXC chemokine/neutrophil activating chemokine (NAC) that regulate neutrophil trafficking during infections and inflammation by binding to its cognate G-protein coupled receptors CXCR1/CXCR2. The "ELR" motif of NAC chemokines is essential for the CXCR1/CXCR2 receptor activation. In order to understand the evolutionary origin of "ELR" motif in the CXC chemokines, a thorough evolutionary study of CXCL8 gene from various fishes and primates was performed. Phylogenetic analysis revealed that the CXCL8 gene can be classified into four distinct lineages (CXCL8-L1a, CXCL8-L1b, CXCL8-L2, and CXCL8-L3), where CXCL8-L1a is the fastest evolving lineage and CXCL8-L3 is the slowest. Selection analysis suggested that The "ELR/DLR" motif containing branches (gadoid and coelacanth) are positively selected. The probable evolutionary trend of "ELR" motif suggested that this motif in ancestor CXCL8 is evolved from the GGR of Lamprey (Agnatha), followed by duplication giving rise to two main motifs in CXCL8 "NXH" in L3 lineage and "ELR/DLR" in L1a/L1b lineages. Although, structural analysis suggested that the overall topology of the CXCL8 proteins is similar, differences do exist at the individual structural elements among the members of different lineages. Functional distance analysis suggested that the CXCL8-L3 lineage is more distant compared to the CXCL8-L1a and L1b lineages from the inferred ancestor. Functional divergence analysis between different lineages suggested that most of the selected residues are important for receptor or glycosaminoglycan binding. Such a functional diversification can be attributed to the novel set of functions adopted by CXCL8 in various species.

Molecular characterization and biological functioning of interleukin-8 in Siberian sturgeon (Acipenser baeri)

Interleukin-8, otherwise known as CXCL8, is a CXC chemokine that plays a pivotal regulatory role in immune and inflammation responses of animals. Here, we identified an interleukin-8 homologue from Siberian sturgeon (Acipenser baeri), named AbIL-8, which belongs to the lineage 1 group of teleost fish IL-8s. The cDNA of Abil-8 is 1130 bp in length, containing a 5'- untranslated region (UTR) of 50 bp, a 3'- UTR of 783 bp, and an open reading frame (ORF) of 297 bp that encodes a protein consisting of 98 amino acids. The deduced AbIL-8 contained five cysteines, four of which are highly conserved, and an ELR motif typical of known mammalian CXC chemokines was also found preceding the CXC motif. Our phylogenetic analysis showed that AbIL-8 clustered with the CXCL8_L1 sequences from other teleosts, being clearly distinct from those of either birds or mammals. Abil-8 mRNA was constitutively expressed in all tested tissues and significantly up-regulated in the liver and spleen tissues by the bacteria Aernomas hydrophila. The in vitro experiment using primary spleen cells stimulated with heat-killed Aernomas hydrophila or lipopolysaccharide (LPS) revealed a similar expression pattern to that found in vivo, whereas stimulation on spleen cells with β-glucan or polyI:C elicited negligible changes in levels of Abil-8 mRNA. Purified recombinant AbIL-8 not only exhibited chemotactic activity for lymphocytes and monocytes in peripheral blood leukocytes (PBLs) and, to a lesser extent, spleen cells, but also stimulated the proliferation of spleen cells at 10 ng/mLor above. Furthermore, intraperitoneal injection of rAbIL-8 also up-regulated the expression of immuno-related genes (IL-6, IgM and MHCIIβ) at 24 h. Collectively, these results enhance our understanding of how IL-8 functions in the regulation of the immune responses in sturgeon.

Dietary supplementation of olive leaf extract increases haematological, serum biochemical parameters and immune related genes expression level in common carp (Cyprinus carpio) juveniles

The present study investigated the effects of dietary olive leaf (Olea europea L.) extract (OLE) on some blood parameters and immune (TNF-α, IL-1ß and IL-8) related genes in different tissues (head kidney, liver and spleen) and resistance of common carp, Cyprinus carpio to Edwardsiella tarda. Five diets were prepared for fed fish (mean body weight 15.90 ± 0.93 g) with different rates of OLE (0.0%, 0.1%, 0.25%, 0.50% and 1.0%). A control diet was prepared non-supplemented with OLE. Increased haematocrit ratio, serum myeloperoxidase activity, immune response gene levels (IL-1β in head kidney tissue and TNF-α in spleen tissue) and survival rate against E. tarda particularly in the 0.1% OLE treatment group. In conclusion, results of the present study show that feeding common carp with a diet containing 1 g/kg OLE over a period of 60 days might be adequate to improve fish immune parameters, and survival rate against E. tarda. Therefore, OLE can be used as a dietary additive to prevent E. tarda in common carp.

Immune stimulation of rainbow trout reveals divergent regulation of MH class II-associated invariant chain isoforms

Major histocompatibility complex (MHC) class II-associated invariant chain is a chaperone responsible for targeting the MHC class II dimer to the endocytic pathway, thus enabling the loading of exogenous antigens onto the MHC class II receptor. In the current study, in vivo and in vitro methods were used to investigate the regulation of the rainbow trout invariant chain proteins S25-7 and INVX, upon immune system activation. Whole rainbow trout and the macrophage/monocyte-like cell line RTS11 were treated with PMA at concentrations shown to induce IL-1β transcripts and homotypic aggregation of RTS11. S25-7 transcript levels remained unchanged in the gill, spleen, and liver and were found to be significantly decreased in head kidney beginning 24 h post-stimulation. Meanwhile, INVX transcript levels remained unchanged in all tissues studied. Both S25-7 and INVX proteins were produced in gill and spleen tissues but their expression was unaffected by immune system stimulation. Surprisingly, neither INVX nor S25-7 protein was detected in the secondary immune organ, the head kidney. Analysis of RTS11 cultures demonstrated that both INVX and S25-7 transcript levels significantly increased at 96 h and 120 h following PMA stimulation before returning to control levels at 168 h. Meanwhile, at the protein level in RTS11, S25-7 remained unchanged while INVX had a significant decrease at 168 h post-stimulation. These results indicate that neither INVX nor S25-7 is upregulated upon immune system activation; thus, teleosts have evolved a system of immune regulation that is different than that found in mammals.

Expression of immune, antioxidant and stress related genes in different organs of common carp exposed to indoxacarb

The aim of the present study was to investigate the effects of chronic exposure of common carp (Cyprinus carpio) to indoxacarb on immune, antioxidant and stress gene expression. After 21 days exposure to 0, 0.75, 1.5 and 3 ppm indoxacarb, expression of IL-1β, IL-8, IL-10, TNF-α, IFN-γ, SOD, CAT, HSP70, IGF-I and IGF-II were assessed in liver, kidney and gills. In general, exposure to low concentration of indoxacarb increased inflammatory cytokine gene expression (IL-1β, IL-8, IL-10, TNF-α and IFN-γ) and inhibits inflammatory cytokines' expression at higher concentrations. The assessment of antioxidant gene expression (SOD and CAT) in different organs indicate that they were increased by low concentrations of indoxacarb to deal with primary oxidative situation. However, higher concentrations of indoxacarb caused reduction in oxidative gene expression. IGF genes expression in liver significantly increased at a concentration of 0.75 ppm treatment, then it decreased at 1.5 ppm indoxacarb and increased again by increasing in the indoxacarb concentration to 3 ppm. The expression of HSP70 in kidney showed a significant elevation in 0.75 and 1.5 ppm treatments compared with 3 ppm treatment and the control group. The expression of this gene in liver was significantly increased in 1.5 and 3 ppm treatments. The same pattern of expression was also observed in gill. Overall, indoxacarb exposure affects common carp health at transcription levels. Changes in the genes expression generally suggest that indoxacarb exposure led to interference in inflammation, oxidative stress and tissue damage.

Effects of inosine 5'-monophosphate supplementation in high fishmeal and high soybean diets on growth, immune-related gene expression in gibel carp (Carassius auratus gibelio var. CAS Ⅲ), and its challenge against Aeromonas hydrophila infection

The present study was conducted to evaluate dietary inosine 5'-monophosphate (5'-IMP) on growth, immune genes expression and disease resistance against Aeromonas hydrophila in juvenile gibel carp (Carassius auratus gibelio var. CAS Ⅲ) (initial body weight: 7.48 g). Six diets were formulated containing exogenous 5'-IMP at three gradient levels (0, 0.1% and 0.2%) in the high dietary fishmeal group (15% fishmeal: D1, D2, D3) and in the high dietary soybean meal group (33% soybean meal: D4, D5, D6). Each diet was randomly allotted to triplicate tanks in a recirculating system. After the feeding trial, fish were exposed to Aeromonas hydrophila challenge. Hematological and immunological responses were analyzed before and after challenge. The results indicated that feeding rate in all 5'-IMP supplemented treatments (D2, D3, D5 and D6) and daily growth coefficient in D5 and D6 were reduced compared with those of respective control treatments (D1 and D4) without 5'-IMP addition (P < 0.05). The cumulative survival rates were numerically improved by dietary 5'-IMP supplementation (P > 0.05). Compared with the respective control treatment, in the high fishmeal group, plasma SOD and MPO were significantly elevated in D3 at the end of feeding trial (P < 0.05), plasma SOD and lysozyme were significantly increased in D3 after bacterial challenge (P < 0.05); in high soybean meal group, plasma lysozyme activity was significantly elevated in D5 post bacterial challenge (P < 0.05). Most of the expression of immune related genes (intelectin, major histocompatibility complex class II β (MHC II β), Complement 3 (C3), Complement component C7-1 (ccC7), lysozyme C, Interleukin 1β (IL-1β), Tumor necrosis factor α1 (TNF-α1), Transforming growth factor-beta (TGF-β) and Interleukin 8 (IL-8)) in spleen, kidney and liver of the fish were significantly affected by supplementation of 5'-IMP at the end of feeding trial and post bacterial challenge. Additionally, adding 5'-IMP in high soybean meal diets exerted further effects of promoting immunity than counterparts in high fishmeal diets. Considering enhanced disease resistance, the immunopotentiation of 5'-IMP was manifested when the addition level was 0.1% in high soybean meal diets and 0.2% in high fishmeal diets.

Molecular characterization and expression analysis of the interleukin 1b gene in Pacific cod (Gadus macrocephalus)

Interleukin 1b (IL-1b) is a member of the cytokine family that serves as major mediators for early pro-inflammatory responses. During artificial breeding of Pacific cod (Gadus macrocephalus), outbreaks of NNV in the early development stages could lead to high mortality. Recent research reported that IL-1b participated in the host-virus interaction against NNV infection, however, no IL-1b gene has been identified from Pacific cod so far. In this study, we described the identification and characterization of a IL-1b from Pacific cod transcriptome at both transcript and protein level. Sequence alignment and phylogenetic analysis were conducted to determine and confirm their evolutionary relationship. Expression analysis revealed that IL-1b was expressed in all tested tissues and the western blot analysis confirmed the same expression profiles using purified recombinant IL-1b protein. In addition, significant up-regulation was detected in IL-1b transcripts during early development stages at 30dph and 50dph. After challenged with poly I:C, IL-1b was significantly induced after 24 h. Taken together, these results strongly suggested that IL-1b might play an essential role in innate defense mechanism of Pacific cod.

Amphibian (Xenopus laevis) Interleukin-8 (CXCL8): A Perspective on the Evolutionary Divergence of Granulocyte Chemotaxis

The glutamic acid-leucine-arginine (ELR) motif is a hallmark feature shared by mammalian inflammatory CXC chemokines such the granulocyte chemo-attractant CXCL8 (interleukin-8, IL-8). By contrast, most teleost fish inflammatory chemokines lack this motif. Interestingly, the amphibian Xenopus laevis encodes multiple isoforms of CXCL8, one of which (CXCL8a) possesses an ELR motif, while another (CXCL8b) does not. These CXCL8 isoforms exhibit distinct expression patterns during frog development and following immune challenge of animals and primary myeloid cultures. To define potential functional differences between these X. laevis CXCL8 chemokines, we produced them in recombinant form (rCXCL8a and rCXCL8b) and performed dose-response chemotaxis assays. Our results indicate that compared to rCXCL8b, rCXCL8a is a significantly more potent chemo-attractant of in vivo-derived tadpole granulocytes and of in vitro-differentiated frog bone marrow granulocytes. The mammalian CXCL8 mediates its effects through two distinct chemokine receptors, CXCR1 and CXCR2 and our pharmacological inhibition of these receptors in frog granulocytes indicates that the X. laevis CXCL8a and CXCL8b both chemoattract tadpole and adult frog granulocytes by engaging CXCR1 and CXCR2. To delineate which frog cells are recruited by CXCL8a and CXCL8b in vivo, we injected tadpoles and adult frogs intraperitoneally with rCXCL8a or rCXCL8b and recovered the accumulated cells by lavage. Our transcriptional and cytological analyses of these tadpole and adult frog peritoneal exudates indicate that they are comprised predominantly of granulocytes. Interestingly, the granulocytes recruited into the tadpole, but not adult frog peritonea by rCXCL8b, express significantly greater levels of several pan immunosuppressive genes.

Effect of dietary yeast nucleotide on antioxidant activity, non-specific immunity, intestinal cytokines, and disease resistance in Nile Tilapia

The present study investigated the effects of dietary supplementation of yeast nucleotides on the hematology, antioxidant activity, non-specific immunity, expression of intestinal cytokines, and disease resistance in Nile Tilapia (Oreochromis niloticus). Fish weighing 42.90 ± 0.14 g were randomly divided into four groups. Each group was set in triplicate (15 fish per replicate). Fish were fed on four dietary levels of yeast nucleotides (NTs) supplemented with the basal diet 0% (control), 0.05%, 0.15%, and 0.25% NTs. Significantly higher total serum protein, albumin, total serum globulin, total WBC counts, and lymphocyte and granulocyte contents were recorded in 0.25% NT group as compared to the control. The albumin/globulin ratio (A:G) showed a considerable decrease in the 0.25% NT group. The non-specific immune parameters; serum killing percentage, lysozyme activity, nitric oxide assay, IgM levels, and anti-protease activity, were significantly higher in the 0.25% NT group as compared to the control. Moreover, a 15-day feeding trial demonstrated improved results in terms of serum lysozyme activity, nitric oxide assay, IgM levels, and anti-protease activity than a 30-day feeding trial. A significant increase in the anti-oxidant status of O. niloticus was noticed, as reflected by increased superoxide dismutase and malondialdehyde activity in the serum of 0.25% NT group compared to the control, while glutathione peroxidase displayed a significant increase in all groups as compared to the control. The intestinal cytokines TGF-β, IL-1β, IL-10β, and TNF-α mRNA levels showed a pattern of 0.25% NT > 0.15% NT > 0.05% NT > 0% NT, as relative to the control Ef-1α levels. The relative survival percentages of fish fed on yeast nucleotide-supplemented diets, as analyzed by exposure to Aeromonas sobria, were significantly better than the control group. In conclusion, dietary yeast nucleotide administration at 0.25% improved blood proteins, leukocytes, antioxidant activity, non-specific immunity, cytokine gene expression, and disease resistance of Nile Tilapia.

New cytokines and TLR pathway signaling molecules in Chinese rare minnow (Gobiocypris rarus): Molecular characterization, basal expression, and their response to chlorpyrifos

In this study, the cDNA fragments of cytokines (il-8) and toll-like receptor (TLR) pathway signaling molecules (myd88, irak-1, irf5, and irf7) in the Chinese rare minnow were cloned and exhibited a high amino-acid sequence identity compared to other cyprinid fish orthologs. The mRNA expressions of these genes in the different tissues (liver, brain, spleen, kidney, and skin) were observed. The highest expression levels of myd88, irak-1, and irf5 were detected in the spleen, whereas il-8 and irf7 were detected in the kidney and liver respectively. The mRNA expression of irak-1, irf5, and irf7 in the liver from 0.1 μg/L and 0.5 μg/L CPF treatments were significantly increased on day 7 (p < 0.05), whereas the levels of only irak-1 and irf7 were markedly increased on day 28 (p < 0.05). Moreover, the mRNA expression of il-8 in the spleen following 0.5 μg/L CPF treatments was significantly decreased on day 7 (p < 0.05), whereas significantly decrease were observed in the levels of irf7 in the spleen at 2.5 μg/L CPF on days 7 and 28 (p < 0.05). The 0.1 μg/L and 0.5 μg/L of CPF significantly induced the levels of irak-1 and myd88 in the spleen after 28 d exposure (p < 0.05). Therefore, the high induction of cytokines and TLR pathway signaling molecules demonstrated that Chinese rare minnow was immune-compromised exposed to CPF. Moreover, our finding indicated that these immune-related genes could be feasible to screen for substances hazardous to the immune system of fish.

Acute exposure to chlorpyrifos induces reversible changes in health parameters of Nile tilapia (Oreochromis niloticus)

Chlorpyrifos (CPF) is one of the most common insecticides found in freshwater ecosystems, and has been detected in agricultural and fishery products worldwide. This study focused on comprehensive panel of hematological, immunotoxic and pathology changes in Nile tilapia (Oreochromis niloticus) during and after exposure to CPF at 15 μg/L (0.043 μM) (1/10 LC₅₀, group CPF1), or 75 μg/L (0.21 μM) (1/2 LC₅₀, group CPF2) for 14 days, followed by 2 weeks recovery. Different endpoints were used to determine effects of CPF on fish health: hematological parameters; antioxidant levels in liver and gills; innate immune parameters; expression levels of pro-inflammatory cytokine genes at mRNA level in anterior kidney and spleen; and histopathological assessment of gills, liver, and kidney tissues. RBCs were significantly decreased in CPF1 group compared to other groups only at day 3. Blood packed cell volume (PCV) and mean corpuscular volume (MCV) showed significant increase at day 3 and 14 of CPF exposure. TLC (Total Leukocytic Counts), neutrophil counts were significantly increased in CPF exposed groups at days 3, 7, 14 compared to the control. While, lymphocytes counts were significantly increased at CPF1 group compared to other groups at day 14. Antioxidant enzyme activity in liver and gills showed significant increase of Malondialdehyde (MDA) and glutathione (GSH), and significant decrease in (catalase/CAT/, glutathione S-transferase/GST/, and superoxide dismutase/SOD/); in CPF exposed groups. Serum bactericidal and lysozyme activity was nominally and significantly decreased, respectively, and whole blood respiratory burst was significantly increased in CPF2 group. The cytokine expression levels showed complex changes in expression patterns. In kidney, cytokine interleukin-8 (IL-8) was significantly upregulated at day 1 in both exposed group. Interleukin-1β (IL-1β) and Tumor necrosis factor-α (TNFα) were significantly upregulated at day 1 in CPF1 group, and then IL-8 and TNFα downregulated at day 3 in same group. At day 7, only TNFα was up and downregulated in CPF1 and CPF2, respectively compared to control. All gene expression levels in spleen were upregulated on day 7 of exposure in the high exposed group. Histopathology showed dose-dependent changes in CPF treated groups, indicating gill, liver, and posterior kidney changes associated with oxidative stress damages. Following recovery period, all measured parameters showed varying degrees in their reversibility to the control level. These findings provide important insights about the acute toxic effects of CPF on fish and show potential to be used as biomarkers in further toxicological evaluation studies.

Transcriptome analysis provides insights into the immune responsive pathways and genes in the head kidney of tiger grouper (Epinephelus fuscoguttatus) fed with Spatholobus suberectus, Phellodendron amurense, or Eclipta prostrata

The tiger grouper, Epinephelus fuscoguttatus, is an economically important fish in Southeast Asia but has been plagued by several diseases. Spatholobus suberectus (S), Phellodendron amurense (P), and Eclipta prostrate (E) are three commonly used Chinese medicinal herbs. Although previous pharmacological and clinical studies indicated that S, P, and E possess a variety of beneficial functions in mammals, little is known about their functions in farmed fish and the underlying molecular mechanism of their actions. Challenge tests in this study showed that after 14 days of diet supplement, all these herbs could effectively enhance the disease resistance of E. fuscoguttatus against Vibrio harveyi. However, the non-specific immune parameters of the herb-supplemented groups were not significantly different from the control group. To further explore the molecular mechanism of herbal immune-regulating effects on E. fuscoguttatus, transcriptome sequencing and RNA-Seq technique were applied on E. fuscoguttatus kidney. De novo transcriptome assembly of E. fuscoguttatus kidney yield 80,014 unigenes, among which, 44,901 (56.12%) were annotated with at least one of the public databases (Nr, Nt, Swiss-Prot, KEGG, COG, GO). Among these, 22,738, 11,700 and 27,457 unigenes were assigned to 57, 25 and 258 categories of GO, COG and KEGG databases, respectively. Using Solexa/Illumina's DGE platform, a total of 231, 186 and 144 putative differentially expressed genes (DEGs) were detected in P, E and S group compared with the control group. GO analysis indicated that in P and E, down-regulated DEGs were dominant in almost every GO term; whereas in S, up-regulated DEGs were more dominant. KEGG pathway analysis revealed that putative DEGs in all three herb groups were obviously enriched in the pathways related to infective diseases and immune system. We also identified a number of immune relative genes and pathways (TLR5, IL8 and MAPK pathway, for instance) associated with P, E and S's regulatory effects on E. fuscoguttatus. This study will enrich the E. fuscoguttatus transcriptome database, contribute to a better understanding of the molecular mechanisms associated with the immunoregulatory activities of Chinese medicinal herbs on teleost and provide valuable information on the prevention of grouper Vibrio diseases using Chinese medicinal herbs.

Changes in growth, blood immune parameters and expression of immune related genes in rainbow trout (Oncorhynchus mykiss) in response to diet supplemented with Ducrosia anethifolia essential oil

An 8- week feeding trial was conducted to investigate the effects of Ducrosia anethifolia essential oil on growth, blood immune parameters and immune related genes expression in juvenile rainbow trout (Oncorhynchus mykiss). Fish were allocated into 4 groups and fed on diet containing different levels of essential oil (0, 0.001, 0.01 and 0.1%) to apparent satiation in 30 min 3 times daily. Growth and immunological parameters were measured every ten days and tissue samples were taken from kidney and spleen on days 10, 30 and 50 to study the expression of IL-1β and TNF-α. The changes of measured parameters in different treatments and over sampling time series were statistically analysis based on repeated measurement method (P < 0.05). Results showed that growth did not affected by essential oil at different treatments. The highest level of hematocrit was observed in 0.001 treatment. The mean of RBC showed no significant differences among treatments. The mean of WBC in 0.01 and 0.1 groups were higher than those in 0.001 and control groups. Total protein, albumin and globulin and serum bactericidal activity showed no significant difference in different treatments. Neither treatments nor sampling times affected serum lysozyme activity. The highest mean of respiratory burst activity was observed in 0.01 group. The highest expression of both IL-1β and TNF-α genes in kidney was observed at 0.001 dose on day 30, while in spleen, the highest expression of IL-1β and TNF-α was obtained on day 30 at doses 0.1 and 0.01%, respectively. In conclusion the results of this study showed that feeding with lower and medium level of D. anethifolia for 30 days led to immunostimulatory effects in juvenile rainbow trout.

A CXCL ortholog from Hippocampus abdominalis: Molecular features and functional delineation as a pro-inflammatory chemokine

Chemokines are a family of chemotactic cytokines that regulate leukocyte migration. They are classified into four groups namely, CXC, CC, C and CX₃C, based on the formation of a disulfide bridge. Among these, CXC chemokines have been identified as the largest group of chemokines in humans. In this study, we identified and functionally characterized a homolog of CXC chemokine from the big-belly seahorse, Hippocampus abdominalis, and designated it as ShCXCL. The cDNA of ShCXCL composed of a 342-bp open reading frame encoding 113 amino acids (aa). The CXC family-specific small cytokine domain (SCY) was identified from the mature peptide region, which comprised of a conserved CXC motif. As ShCXCL lacks an ELR (Glutamic acid-Leucine-Arginine) motif, it belongs to ELR^- subfamily. The recombinant ShCXCL protein strongly induced the nitric oxide (NO) production in macrophage cells (RAW 264.7 cell line) and showed the chemotactic effect on flounder peripheral blood leukocytes. Tissue profiling showed a ubiquitous expression pattern in all examined tissues, with a high abundance in spleen. The up-regulated mRNA expression pattern of ShCXCL was observed in blood and kidney tissues after immune stimulation by live bacteria, such as Streptococcus iniae and Edwardsiella tarda, and mitogens, such as lipopolysaccharides (LPS) and polyinosinic:polycytidylic acid (poly I:C), suggesting its important role in host immune defense against microbial infection.