Characterization of IL-1β and two types of IL-1 receptors in miiuy croaker and evolution analysis of IL-1 family

Identification of potential geosmin-binding proteins in grass carp gill based on affinity responsive target stability and tandem mass tag proteomics

The escalating issue of water pollution, especially the accumulation of organic off-flavor pollutants, poses significant challenges. Geosmin, a typical off-flavor compound in aquatic environments, not only compromises the quality of aquatic products but also deters consumers. Its impact extends to aquatic organisms, with current research focusing on dose-response and ecotoxicity, while neglecting the molecular-level study of geosmin-binding proteins. This study employs an integrated approach combing affinity-responsive target stability in vitro, tandem mass tag proteomics in vivo, and molecular docking to identify geosmin-binding proteins in the gill tissue of grass carp (Ctenopharyngodon idella). ARTS analysis identified 56 proteins, predominantly membrane-associated proteins, such as catenin beta-1, annexin, and integrin beta. Proteomic analysis revealed 256 differentially expressed proteins in geosmin-exposure group, with 18 common proteins screened by in vivo and in vitro methods. Among these, annexin, cathepsin D, and interleukin-1 receptors were highlighted as potential geosmin targets, with annexin demonstrating the highest binding affinity in silico. This study provides a robust protocol integrating in vivo, in vitro, and in silico approaches to elucidate geosmin's target proteins in grass carp gill tissue, advancing our understanding of pollutant-biological interactions and enhancing environmental risk assessment accuracy.

Cortisol suppresses lipopolysaccharide-induced in vitro inflammatory response of large yellow croaker (Larimichthys crocea) via the glucocorticoid receptor and p38 mitogen-activated protein kinase pathways

Glucocorticoids (GCs) are well-established anti-inflammatory agents, with cortisol, an endogenous GC, exerting pivotal regulatory effects on normal physiological processes. However, the immune regulatory role of cortisol in teleost fish, particularly in inflammation induced by pathogenic infection, remains largely unexplored. Here, we revealed that lipopolysaccharide (LPS) triggers a pro-inflammatory response in the large yellow croaker (Larimichthys crocea), as evidenced by increased expression of key pro-inflammatory cytokines and activation of the mitogen-activated protein kinase (MAPK) signaling pathway. We further explored the immunosuppressive capacity of cortisol in LPS-stimulated large yellow croaker kidney cells (PCK cells) and in vitro tissues of the large yellow croaker. Our findings indicated that cortisol effectively suppresses LPS-induced overexpression of pro-inflammatory cytokines and p38 MAPK pathway activation. Moreover, the immunosuppressive effects of cortisol were reversed by pretreatment with mifepristone, a glucocorticoid receptor (GR) antagonist. Collectively, this study delineated the inhibitory role of cortisol in the LPS-induced inflammatory cascade in large yellow croaker and underscores the significance of GR in mediating this response. These insights advance our comprehension of GCs-mediated immune modulation and provide a theoretical basis for the application of cortisol in disease prevention and the selective breeding of disease-resistant traits in aquaculture.

Characterization of the impact of dietary immunostimulant CpG on the expression of mRNA biomarkers involved in the immune responses in Atlantic salmon (Salmo salar)

Infectious diseases have significantly impacted Atlantic salmon aquaculture worldwide. Modulating fish immunity with immunostimulant-containing functional feeds could be an effective strategy in mitigating disease problems. Previously, we characterized the impact of polyriboinosinic polyribocytidylic acid (pIC) and formalin-killed typical Aeromonas salmonicida bacterin on miRNA expression in Atlantic salmon fed a commercial diet with and without immunostimulant CpG. A set of miRNA biomarkers of Atlantic salmon head kidney responding to pIC and/or bacterin immune stimulations was identified (Xue et al., 2019) [1]. Herein, we report a complementary qPCR study that investigated the impact of the pIC, bacterin and dietary CpG on the expression of immune-relevant mRNAs (n = 31) using the same samples as in the previous study (Xue et al., 2019) [1]. Twenty-six of these genes were predicted target transcripts of the pIC- and/or bacterin-responsive miRNAs identified in the earlier study. The current data showed that pIC and/or bacterin stimulations significantly modulated the majority of the qPCR-analyzed genes involved in various immune pathways. Some genes responded to both stimulations (e.g. tnfa, il10rb, ifng, irf9, cxcr3, campb) while others appeared to be stimulation specific [e.g. irf3, irf7a, il1r1, mxa, mapk3 (pIC only); clra (bacterin only)]. A. salmonicida bacterin stimulation produced a strong inflammatory response (e.g. higher expression of il1b, il8a and tnfa), while salmon stimulated with pIC showed robust interferon responses (both type I and II). Furthermore, the current data indicated significant down-regulation of immune-relevant transcripts (e.g. tlr9, irf5, il1r1, hsp90ab1, itgb2) by dietary immunostimulant CpG, especially among pre-injection and PBS-injected fish. Together with our prior miRNA study, the present research provided complementary information on Atlantic salmon anti-viral and anti-bacterial immune responses and on how dietary CpG may modulate these responses.

Pathological variations and immune response in Channa argus infected with pathogenic Nocardia seriolae strain

Nocardia seriolae pathogen causes chronic granulomatous disease, reportedly affecting over 40 species of marine and freshwater cultured fish. Hence, research is required to address and eliminate this significant threat to the aquaculture industry. In this respect, a reliable and reproducible infection model needs to be established to better understand the biology of this pathogen and its interactions with the host during infection, as well as to develop new vaccines or other effective treatment methods. In this study, we examined the pathogenicity of the pathogen and the immune response of snakehead (Channa argus) juvenile to N. seriolae using a range of methods and analyses, including pathogen isolation and identification, histopathology, Kaplan-Meier survival curve analysis, and determination of the median lethal dose (LD50) and cytokine expression. We have preliminarily established a N. seriolae - C. argus model. According to our morphological and phylogenetic analysis data, the isolated strain was identified as N. seriolae and named NSE01. Eighteen days post-infection of healthy juvenile C. argus with N. seriolae NSE01, the mortality rate in all four experimental groups (intraperitoneally injected with 1 × 105 CFU/mL - 1 × 108 CFU/mL of bacterial suspension) (n = 120) was 100 %. The LD50 of N. seriolae NSE01 for juvenile C. argus was determined to be 1.13 × 106 CFU/fish. Infected juvenile C. argus had significant pathological changes, including visceral tissue swelling, hemorrhage, and the presence of numerous nodules of varying sizes in multiple tissues. Further histopathological examination revealed typical systemic granuloma formation. Additionally, following infection with N. seriolae NSE01, the gene expression of important cytokines, such as Toll-like receptor genes TLR2, TLR13, interleukin-1 receptor genes IL1R1, IL1R2, and interferon regulatory factor IRF2 were significantly upregulated in different tissues, indicating their potential involvement in the host immune response and regulation against N. seriolae. In conclusion, juvenile C. argus can serve as a suitable model for N. seriolae infection. The establishment of this animal model will facilitate the study of the pathogenesis of nocardiosis and the development of vaccines.

Transcriptomic insights into the immune response of the intestine to Aeromonas veronii infection in northern snakehead (Channa argus)

Intestinal inflammation is a protective response that is implicated in bacterial enteritis triggered by gastrointestinal infection. The immune mechanisms elicited in teleost against the infection of Aeromonas veronii are largely unknown. In this study, we performed a de novo northern snakehead (Channa argus) transcriptome assembly using Illumina sequencing platform. On this basis we performed a comparative transcriptomic analysis of northern snakehead intestine from A. veronii-challenge and phosphate buffer solution (PBS)-challenge fish, and 2076 genes were up-regulated and 1598 genes were down-regulated in the intestines infected with A. veronii. The Gene Ontology (GO) enrichment analysis indicated that the differentially expressed genes (DEGs) were enriched to 27, 21 and 20 GO terms in biological process, cellular component, and molecular function, respectively. A Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that 420 DEGs were involved in 194 pathways. Moreover, 33 DEGs were selected for quantitative real-time PCR analysis to validate the RNA-seq data. The results reflected the consistency of the expression levels between qRT-PCR and RNA-seq data. In addition, a time-course analysis of the mRNA expression of 33 immune-related genes further indicated that the intestinal inflammation to A. veronii infection simultaneously regulated gene expression alterations. The present study provides transcriptome data of the teleost intestine, allowing us to understand the mechanisms of intestinal inflammation triggered by bacterial pathogens. DATA AVAILABILITY STATEMENT: All data supporting the findings of this study are available within the article and Supplementary files. The RNA-seq raw sequence data are available in NCBI short read archive (SRA) database under accession number PRJNA615958.

Pathogenicity of fish pathogen Pseudomonas plecoglossicida and preparation of its inactivated vaccine

Many fishes infected with Pseudomonas plecoglossicida generally suffer from "visceral white spot disease" or even die. In this study, a dominant pathogen strain was isolated from the intestinal tract of diseased crucian carp in the Wangcheng Lake area, Changsha, and it was identified as P. plecoglossicida. The selected strain was a new strain named as P. plecoglossicida LQJ06.Strain LQJ06 basically colonized the intestine and poisoned zebrafish as show by fluorescent labelling.Pathological structural analysis of tissue sections indicated that the intestinal tract was seriously damaged, epithelial cells in the intestinal tissue were necrotic, intestinal villi were sloughed, liver cells were vacuolated, nuclei were pyknotic and shifted, and lymphocytes were proliferated in the spleen. P. plecoglossicida LQJ06 strain could invade and proliferate in the grass carp liver cell line L8824, which led to a stress response, including apoptosis.Cell morphology was changed owing to the toxicity of the culture supernatant of the LQJ06 strain, which mainly manifested as aggregation between cells, pyknosisd and slow growth or even death.An inactivated vaccine derived from P. plecoglossicida LQJ06 prepared in this study was safe and nontoxic to grass carp liver cells. Compared with those after oral administration, most of the cellular immune factors were expressed earlier and at a higher level after injection immunization. The intestinal tract and liver from zebrafish mainly expressed the IFN-γ2 and IL-1β genes, respectively, after immunization. The upregulation of these immune-related genes proved that the vaccine could strengthen the immunity of zebrafish, induce inflammation and promote resistance to pathogenic infection. The results of these preliminary tests provide a scientific basis for further research on the prevention and control of P. plecoglossicida, and an essential preliminary basis for the development of an inactivated vaccine against P. plecoglossicida.

Meteorin-like/Meteorin-β upregulates proinflammatory cytokines via NF-κB pathway in grass carp Ctenopharyngodon idella

Meteorin-like (Metrnl) is a newly discovered cytokine but whether it exists in fish is unclear. In this study, we identified two Meteorin-like (Metrnl) homologues in grass carp Ctenopharyngodon idella (termed CiMetrnl-a and CiMetrnl-b) which share high sequence homology and conserved genomic organization of 4 exons and 3 introns with known Metrnl molecules. Also, gene synteny of Metrnl genes is well conserved in vertebrates. Expression analyses showed that the CiMetrnl-a gene was constitutively expressed in tissues of healthy fish whilst the levels of CiMetrnl-b transcripts were too low to be detected. The CiMetrnl-a gene was inducible by Flavobacterium columnare, grass carp reovirus and PAMPs. Recombinant CiMetrnl-a produced in the CHO-S cells was active in up-regulating the expression of cytokines involved in promoting inflammation (IL-1β, IL-6, IL-8, IL-17A and TNF-α), type 1 immune response (IFN-γ and IL-2) and NF-κB signaling pathway (NF-κBp65 and NF-κBp52) in the primary head kidney leukocytes. Furthermore, luciferase reporter assay showed that CiMetrnl-a was able to activate the NF-κB promoter in the EPC cells, suggesting that CiMetrnl-a may upregulate pro-inflammatory cytokines via NF-κB dependent pathway.

Transcriptome analysis in Takifugu rubripes and Dicentrarchus labrax gills during Cryptocaryon irritans infection

Takifugu rubripes and Dicentrarchus labrax are important commercial fish in China that are under serious threat from Cryptocaryon irritans. C. irritans is a ciliated obligate parasite that causes marine white spot disease and leads to heavy economic losses. We analysed the transcriptome in the gills of T. rubripes and D. labrax to compare differentially expressed genes (DEGs) and pathways during infection with C. irritans. In total, we identified 6,901 and 35,736 DEGs from T. rubripes and D. labrax, respectively. All DEGs were annotated into GO terms; 6,901 DEGs from T. rubripes were assigned into 991 sub-categories, and 35,736 DEGs from D. labrax were assigned into 8,517 sub-categories. We mapped DEGs to the KEGG database and obtained 153 and 350 KEGG signalling pathways from T. rubripes and D. labrax, respectively. Immune-related categories included Toll-like receptors, MAPK, lysosome, C-type lectin receptor and NOD-like receptor signalling pathways were significantly enriched pathways. In immune-related signalling pathways, we found that AP-1, P38, IL-1β, HSP90 and PLA were significantly up-regulated DEGs in T. rubripes, but P38 and PLA were significantly down-regulated in D. labrax. In this study, transcriptome was used to analyse the difference between scaly and non-scaly fish infection by C. irritans, which not only provided a theoretical basis for the infection mechanism of C. irritans, but also laid a foundation for effectively inhibiting the occurrence of this disease. Our work provides further insight into the immune response of host resistance to C. irritans.

Bacteria-induced IL-1β and its receptors in snakehead (Channa argus): Evidence for their involvement in antibacterial innate immunity

As a central pro-inflammatory cytokine, interleukin-1β (IL-1β) plays critical roles in the inflammatory response, pathogen infection, and immunological challenges in mammals. Although fish IL-1β has been confirmed to participate in inflammatory response to pathogen infection, few studies have been performed to characterize the antibacterial and bactericidal functions of fish IL-1β. In this study, snakehead (Channa argus) IL-1β (shIL-1β) and its receptors, shIL-1R1 and shIL-1R2, were cloned and functionally characterized. ShIL-1β contained the IL-1 family signature domain, and a potential cutting site at Asp⁹⁶ that presented in all vertebrate IL-1β sequences. ShIL-1R1 had three extracellular IG-like domains and one intracellular signal TIR domain, while shIL-1R2 had three extracellular IG-like domain but lacked the intracellular signal TIR domain. ShIL-1β, shIL-1R1, and shIL-1R2 were constitutively expressed in all tested tissues, and their expressions could be induced by Aeromonas schubertii and Nocardia seriolae in the head kidney and spleen in vivo, and by LTA, LPS, and Poly (I:C) in head kidney leukocytes (HKLs) in vitro. Moreover, recombinant shIL-1β upregulated the expression of endogenous shIL-1β, shIL-R1, and shIL-R2 in snakehead HKLs, and enhanced intracellular bactericidal activity. Taken together, this study found that, like IL-1β and its receptors in mammals, shIL-1β and its receptors play crucial roles in antibacterial innate immunity. This provides new insight into the evolution of IL-1β function in vertebrates.

Interleukin-1 Ligands and Receptors in Lumpfish (Cyclopterus lumpus L.): Molecular Characterization, Phylogeny, Gene Expression, and Transcriptome Analyses

The interleukin (IL)-1 family play a fundamental role as immune system modulators. Our previous transcriptome-analyses of leukocytes from lumpfish (Cyclopterus lumpus L.) showed that IL-1β was among the most highly upregulated genes following bacterial exposure. In the present study, we characterized IL-1 signaling pathways, identified and characterized four ligands of the IL-1 family in lumpfish; IL-1β type I and type II, IL-18, and the novel IL-1 family members (nIL-1F), both at mRNA and gene levels. The two IL-1β in lumpfish is termed IL-1β1 (type II) and IL-1β2 (type I). Furthermore, a comprehensive phylogenetic analysis of 277 IL-1 ligands showed that nIL-1F, in common with IL-1β, likely represents an ancestral gene, as representatives for nIL-1F were found in cartilaginous and lobe-finned fish, in addition to teleosts. This shows that nIL-1F is not exclusively present in teleosts as previously suggested. Our analyses of exon-intron structures, intron phases, phylogeny and synteny clearly show the separation of IL-1β into groups; type I and type II, which likely is a result of the third whole genome duplication (3R WGD). The phylogenetic analysis shows that most teleosts have both type I and type II. Furthermore, we have determined transcription levels of the IL-1 ligands in leukocytes and 16 different tissues, and their responses upon in vitro stimulation with seven different ligands. In addition, we have identified the IL-1 receptors IL-1R1, IL-1R2, IL-1R4 (ST2/IL-33 receptor/IL-1RL), IL-1R5 (IL-18R1), and partial sequences of DIGIRR and IL-1R3 (IL-RAcP). Identification of immune molecules and description of innate responses in lumpfish is interesting for comparative and evolutionary studies and our study constitutes a solid basis for further functional analyses of IL-1 ligands and receptors in lumpfish. Furthermore, since lumpfish are now farmed in large numbers to be used as cleaner fish for removal of sea lice on farmed salmon, in-depth knowledge of key immune molecules, signaling pathways and innate immune responses is needed, as the basis for design of efficient immune prophylactic measures such as vaccination.

microRNA-21 negatively regulates NF-κB signaling pathway via targeting IL1R1 in miiuy croaker

microRNAs (miR) are non-coding RNAs that regulates many biochemical processes, such as cell growth, proliferation and immune response. In this study, the regulation of microRNA-21 (miR-21) to the nuclear factor kappaB (NF-κB) signaling pathway by target IL1R1 has been researched in miiuy croaker. First, we predicted the target gene of miR-21 through bioinformatics, and found that IL1R1 is a direct target of miR-21. Then, we found that the over-expression of miR-21 mimics and the pre-miR-21 plasmid inhibits the luciferase levels of the wild-type of IL1R1-3'UTR. miR-21 inhibitors increase the luciferase levels of IL1R1-3'UTR. Additionally, we also observed that the miR-21 could negative regulate the IL1R1 at the level of translation. At last, this study will help to further understand the immunomodulatory mechanisms of miRNAs in teleost fish after being invaded by pathogens.

Scophthalmus maximus interleukin-1β limits Edwardsiella piscicida colonization in vivo

Interleukine-1β (IL-1β) is the first identified pro-inflammatory cytokine, which is cleaved by caspase-1 following the inflammasomes activation, playing critical roles in innate immunity. However, few studies have been performed to characterize the IL-1β in lower vertebrates. Herein, we distinguished the Scophthalmus maximus IL-1β (SmIL-1β) from three IL-1β like sequences and found that SmIL-1β was cleaved by S. maximus caspase at a non-conserved Asp⁸⁶, then targeted to the plasma membrane. Moreover, during the immersion infection of Edwardsiella piscicida, we found that E. piscicida were mainly colonized in gills at early time points and invaded to systemic sites after 5 days post infection, which was consistent with the dynamic up-regulated transcription of SmIL-1β. Furthermore, knockdown of SmIL-1β promotes the bacterial colonization in gills at early time points and result into systemic colonization, while overexpression of SmIL-1β hampers the bacterial colonization in both spleen and kidney. Taken together, these data provide new insights into the molecular mechanisms of SmIL-1β and reveal its role in limiting bacterial infection in vivo, which will support the idea for better understanding the evolutionary of IL-1β functions in teleost.

A novel calreticulin-related molecule that interacts with bacteria and enhances host resistance against bacterial infection in black rockfish, Sebastes schlegeli

Calreticulin (CRT) is a highly conserved and multi-functional protein with diverse localizations. CRT has lectin-like properties and possesses important immunological activities in mammalian. In teleost, very limited studies on CRT immunologic function have been documented. In the present study, a CRT homologue (SsCRT) was cloned, identified and characterized from black rockfish, Sebastes schlegeli, an important aquaculture species in East Asia. The full length of SsCRT cDNA is 2180 bp and encoded a polypeptide of 425 amino acids. SsCRT contains a signal peptide, three distinct structural and functional domains (N-, P- and C-domains), and an endoplasmic reticulum (ER) retrieval signal sequence (KDEL). The deduced amino acid sequence of SsCRT shares 89-92% overall sequence identities with the CRT proteins of several fish species. SsCRT was distributed ubiquitously in all the detected tissues and was highly expressed in the spleen, muscle and liver. After the infection of fish extracellular bacterial pathogen Vibrio anguillarum and intracellular bacterial pathogen Edwardsiella tarda, the mRNA transcripts of SsCRT in spleen, liver, and head kidney were significantly up-regulated. The expression patterns were time-dependent and tissue-dependent. Recombinant SsCRT (rSsCRT) exhibited apparent binding activities against different bacteria and PAMPs. In vivo studies showed that the expressions of multiple immune-related genes such as TNF13B, IL-1β, IL-8, SAA, Hsp70, and ISG15 in head kidney were significantly enhanced when black rockfish were treated with rSsCRT. Furthermore, rSsCRT reduced pathogen dissemination and replication in fish kidney and spleen. These results indicated that SsCRT served as an immune receptor to recognize and eliminate the invading pathogens, which played a vital role in the immune response of Sebastes schlegeli. These findings provide new insights into understanding the roles of CRT proteins in immune response and pathogen infection in teleost.

Transcriptome analysis of juvenile genetically improved farmed tilapia (Oreochromis niloticus) livers by dietary resveratrol supplementation

Here we used RNA-Seq to explore the transcriptomic response and specific involvement of hepatic mRNA of juvenile Oreochromis niloticus (GIFT) as a result of dietary resveratrol supplementation (0.05 g/kg RES). More than 24,513,018 clean reads were reference genome guided assembly into 23,417 unigenes. 12,596 unigenes (29.64%) were annotated to GO database. There were 5, 179 and 1526 genes significantly differentially expressed genes at 15, 30 and 45 d respectively, and 8 KEGG pathways were enriched associated with this immune response. Hyperemia and compressed hepatic sinusoid, fibrosis of liver cell and abnormal hepatic epidermal cell revealed by H&E and SEM analysis respectively. Genes related with cytokine production (il12rb2, scfr), immune system (ig8l, hlfl, cd226, prf1l), autophagy regulation (atg4b), foxo signaling (ccnb2), steroid hormone biosynthesis (cyp3a40), fatty acid metabolism (scd1), metabolism (cacna1b) have been significantly decreased, while genes associated with such pathways above (leap-2, prdx4, mb, homer1, mif, sat1, cytbc1_8) and the pathway of protein processing in endoplasmic reticulum (cne1, tram1) have been significantly increased. These findings suggested RES activated some immune and biological process-related genes to enhance GIFT's innate immunity. It also suggested high concentration addition or long-time administration may bring negative effect in tilapia liver.

Comparative transcriptomic analysis reveals the gene expression profiles in the liver and spleen of Japanese pufferfish (Takifugu rubripes) in response to Vibrio harveyi infection

Japanese pufferfish (Takifugu rubripes) is one of the main marine aquatic fish species cultured in Asia due to its high nutritional value. In recent years, disease caused by Vibrio harveyi infections have led to serious mortality in Japanese pufferfish industry. To understand the complex molecular mechanisms between V. harveyi and Japanese pufferfish, we performed a transcriptome analysis of liver and spleen samples from Japanese pufferfish at 1 and 2 day post-infection. Between-group comparisons revealed 922 genes that were significantly differentially expressed. The altered genes emphasized the function in several immune related pathways including MAPK signaling pathway, JAK-STAT signaling pathway, toll-like receptor signaling pathway, cytokine-cytokine receptor interaction and lysosomal pathway. The data generated in this study provided insight into the responses of Japanese pufferfish against V. harveyi at the transcriptome level, promoting our comprehensive understanding of immune responses for aquatic animal against V. harveyi.

High mobility group box 2 of black rockfish Sebastes schlegelii: Gene cloning, immunoregulatory properties and antibacterial effect

High-mobility group box 2 (HMGB2) is a non-histone chromosomal protein that involved diverse functions such as transcriptional regulation and innate immune responses in mammalian. In teleost, very limited studies on HMGB2 proteins have been documented. Black rockfish (Sebastes schlegelii) is an economic fish species and cultured worldwide. However, the study of black rockfish about immunology is very scarce. In the present study, a HMGB2 homologue gene (SsHMGB2) was identified and characterized in black rockfish. The open reading frame of SsHMGB2 is 648 bp, and the deduced amino acid sequence of SsHMGB2 shares 74.4%-91.2% overall sequence identities with the HMGB2 proteins of several fish species. In silico analysis identified several conserved features, including two basic HMG boxes and an acidic C-terminal tail composed of 24 Asp/Glu residues. Expression of SsHMGB2 occurred in multiple tissues and was upregulated during pathogens infection. Recombinant SsHMGB2 (rSsHMGB2) exhibited apparent binding activities against DNA. In vivo studies showed that the expressions of multiple immune-related genes in head kidney were significantly enhanced when black rockfish were treated with rSsHMGB2. Furthermore, rSsHMGB2 reduced pathogen dissemination and replication in fish kidney and spleen. Taken together, these results suggest that SsHMGB2 possesses apparent immunoregulatory properties and played a role in fighting bacterial infection.

Identification of Caspase-6 and Caspase-7 from miiuy croaker and evolution analysis in fish

Apoptosis is a basic biological phenomenon of cells, which is an important component in the evolution of organisms, the stabilization of the internal environment and the development of multiple systems. In addition, the caspase protein family plays an important role in these pathways of apoptosis. Among them, apoptotic executors can directly act on specific substrates to complete the apoptotic response. In this study, we identified the Caspase-6 and Caspase-7 genes of miiuy croaker, and then analyzed the evolution of the whole Caspase family, furthermore described the evolutionary selection sites of the caspase-6 and caspase-7 genes in fish. The results showed that Caspase-6 gene appeared earlier than Caspase-7 in species evolution and gene duplication in teleost fish. Moreover, we also found that caspase-6 gene had no potential positive selection sites in the evolution of fish. Unlike the caspase-6 gene, the caspase-7 gene did not appear to be missed or replicated during the evolution of the species, while, it to be found two potential positive selection sites.

Anti-Inflammatory Effects of Gingerol on Lipopolysaccharide-Stimulated RAW 264.7 Cells by Inhibiting NF-κB Signaling Pathway

Gingerol was the main functional substance of Zingiberaceous plant which has been known as traditional medicine for thousands of years. The purpose of this experiment was to explore anti-inflammatory effects of gingerol and study the possible mechanism in lipopolysaccharide (LPS)-stimulated RAW246.7 cells. The cells were treated with 10 μg/mL LPS and 300, 200, 100, and 50 μg/mL gingerol for 24 h. The cytotoxicity of gingerol was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetra-zoliumbromide (MTT) method. Nitric oxide (NO) production was observed using Griess assays. Prostaglandin E₂ (PGE₂) and pro-inflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6 have been analyzed by ELISA. Real-time PCR was used to detect the mRNA expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), IL-6, and IL-1β in LPS-induced RAW246.7 cells. Nuclear transcription factor kappa-B (NF-κB) signaling pathway-related proteins have been assessed by western blot assays. The determination of MTT showed that cell viability was not significantly affected by up to 300 μg/mL gingerol. Compared with LPS group, 50, 100, 200, and 300 μg/mL gingerol can inhibit the production of NO and the inhibitory rate was 10.4, 29.1, 58.9, and 62.4%, respectively. The results indicated gingerol existed anti-inflammatory effect. In addition, gingerol also observably inhibited LPS-induced TNF-α, IL-1β, IL-6, and PGE₂ (p < 0.01) expression and secretion in a dose-dependent manner. At the genetic level, after the intervention of gingerol, mRNA transcriptions of iNOS, COX-2, IL-6, and IL-1β were all decreased. The protein expressions of iNOS, NF-κB, p-p65, and p-IκB were significantly increased in LPS-induced cells, while these changes were reversed by the treatment with gingerol. This study suggested that gingerol exerts its anti-inflammatory activities in LPS-induced macrophages which can inhibit the production of inflammatory cytokines by targeting the NF-κB signaling pathway.

The evolution and functional characterization of miiuy croaker interferon regulatory factor 9 involved in immune response

Interferon regulatory factors (IRFs) are transcription factors which play important roles in regulating the expression of type I interferons (IFNs) and IFN-stimulated genes. IRF9 is one of the IRF family gene members which belongs to the IRF4 subfamily. Mammalian IRF9 has been known to be involved in antiviral responses as the DNA sequence recognition subunit of IFN-stimulated gene factor 3 (ISGF3) complex. In fish, only a few studies investigated the characteristics of IRF9 and the role in IFN signaling. In this study, we identified the IRF9 gene from miiuy croaker (mmiIRF9) and studied its feature and function. Sequence analysis showed the similarity of mmiIRF9 and other fish IRF9 genes. Structural and syntenic analysis showed the conservatism in fish IRF9 genes. The result of expression analysis in normal tissues and infected tissues and macrophages showed that mmiIRF9 expressed in all tested normal tissues and up-regulated expression in liver, kidney and macrophages after stimulated with poly(I:C). Luciferase reporter assays demonstrated the mmiIRF9 can induced IFNα and IFNβ luciferase reporters and the cellular localization of mmiIRF9 was mainly distributed in the cytoplasm in Hela cells. Furthermore, the evolutionary analysis of IRF4 subfamily showed the IRF4 and IRF8 may be the most ancient and conservative genes in the evolution of this subfamily.