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Vibrio parahaemolyticus , as one of the main pathogens of marine vibriosis, has brought huge losses to aquaculture. However, the interaction mechanism between V. parahaemolyticus and Epinephelus coioides remains unclear. Moreover, there is a lack of comprehensive multi-omics analysis of the immune response of grouper spleen to V. parahaemolyticus . Herein, E. coioides was artificially injected with V. parahaemolyticus , and it was found that the mortality was 16.7% in the early stage of infection, and accompanied by obvious histopathological lesions in the spleen. Furthermore, 1586 differentially expressed genes were screened by mRNA-seq. KEGG analysis showed that genes were significantly enriched in immune-related pathways, Acute-phase immune response, Apoptosis, Complement system and Cytokine-cytokine receptor interaction. As for miRNA-seq analysis, a total of 55 significantly different miRNAs were identified. Further functional annotation analysis indicated that the target genes of differentially expressed miRNAs were enriched in three important pathways (Phosphatidylinositol signaling system, Lysosome and Focal adhesions). Through mRNA-miRNA integrated analysis, 1427 significant miRNA-mRNA pairs were obtained and " p53 signaling pathway", "Intestinal immune network for IgA production" were considered as two crucial pathways. Finally, miR-144-y , miR-497-x , novel-m0459-5p , miR-7133-y , miR-378-y , novel-m0440-5p and novel-m0084-3p may be as key miRNAs to regulate immune signaling pathways via the miRNA-mRNA interaction network. The above results suggest that the mRNA-miRNA integrated analysis not only sheds new light on the molecular mechanisms underlying the interaction between host and V. parahaemolyticus but also provides valuable and new insights into resistance to vibrio infection., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Qiao, Lu, Xu, Deng, Lai, Wu, Lin, Zhang and Lu.)

Coronavirus disease 2019 (COVID-19) raises the issue of how hypoxia destroys normal physiological function and host immunity against pathogens. However, there are few or no comprehensive omics studies on this effect. From an evolutionary perspective, animals living in complex and changeable marine environments might develop signaling pathways to address bacterial threats under hypoxia. In this study, the ancient genomic model animal Takifugu obscurus and widespread Vibrio parahaemolyticus were utilized to study the effect. T . obscurus was challenged by V . parahaemolyticus or (and) exposed to hypoxia. The effects of hypoxia and infection were identified, and a theoretical model of the host critical signaling pathway in response to hypoxia and infection was defined by methods of comparative metabolomics and proteomics on the entire liver. The changing trends of some differential metabolites and proteins under hypoxia, infection or double stressors were consistent. The model includes transforming growth factor-β1 (TGF-β1), hypoxia-inducible factor-1α (HIF-1α), and epidermal growth factor (EGF) signaling pathways, and the consistent changing trends indicated that the host liver tended toward cell proliferation. Hypoxia and infection caused tissue damage and fibrosis in the portal area of the liver, which may be related to TGF-β1 signal transduction. We propose that LRG (leucine-rich alpha-2-glycoprotein) is widely involved in the transition of the TGF-β1/Smad signaling pathway in response to hypoxia and pathogenic infection in vertebrates as a conserved molecule., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Xu, Yu, Ye, Gao, Deng, Lu, Lin, Zhang and Lu.)

Vibrio parahaemolyticus is an important marine pathogen that cause inflammation even death in teleost. It has brought huge economic losses to aquaculture and serious threats to the sustainable development of marine fisheries. Here, we isolated the DNA, RNA, and total flagellin from V. parahaemolyticus, and obtained the primary spleen and head kidney cells (including leukocytes) from Tetraodon nigroviridis. V. parahaemolyticus DNA, RNA, and total flagellin were used to treat the T. nigroviridis primary cells described above. The results show that the nitric oxide (NO) production and respiratory burst response were significantly induced after stimulation with V. parahaemolyticus total flagellin in T. nigroviridis head kidney and spleen cells. And total flagellin could promote the gene expression and protein production of IL-1β in T. nigroviridis leukocytes. T. nigroviridis TLR5M (TnTLR5M) and TLR5S (TnTLR5S) ORF sequences were obtained as the main recognition receptor for flagellin. Real-time fluorescent quantitative PCR (qRT-PCR) was performed to detect the expression of pattern recognition receptor TnTLR5M and TnTLR5S, the important signal molecule of inflammatory system TnMyD88 and TnTRAF6, and inflammatory cytokines TnIL-1β and TnIFN-γ2. The results show that there were a significant upregulation after challenge with V. parahaemolyticus total flagellin. We further demonstrated that the total flagellin of V. parahaemolyticus could activate the luciferase activity of the NF-κB reporter gene mediated by TnTLR5M. Overall, our results suggest that V. parahaemolyticus total flagellin activated the NO production, respiratory burst response, and inflammatory cytokines expressions, such as TnIL-1β and TnIFN-γ2, through the TnTLR5M-NF-κB signaling pathway in T. nigroviridis., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Vibrio parahaemolyticus , one of the major causes of vibriosis in aquatic animals, causes inflammation that may be related to tissue damage. Flagellin is the major structural component of the flagellum, and also an important virulence factor of bacteria. The filament of V. parahaemolyticus flagellum is composed of multiple flagellin subunits, including FlaA, FlaB, FlaC, FlaD, FlaE, and FlaF which are related to virulence. We produced six V. parahaemolyticus recombinant flagellin through prokaryotic expression including r V.p FlaA, r V.p FlaB, r V.p FlaC, r V.p FlaD, r V.p FlaE, and r V.p FlaF. The primary spleen and head kidney cells (including leukocytes) of Tetraodon nigroviridis were obtained, and the recombinant flagellins were used as stimulants. In this study, the recombinant V. parahaemolyticus flagellin on pro-inflammatory mediators including the release of nitric oxide (NO) and reactive oxygen species, as well as the expression of inflammatory cytokines IL-1β and IFNγ2 etc were detected. The results showed that the NO production and respiratory burst response were significantly induced after stimulation with r V.p FlaF in T. nigroviridis head kidney and spleen cells. Our results also showed that the mRNA levels of T. nigroviridis toll-like receptor 5 M (Tn TLR5M), Tn TLR5S, and downstream genes, such as myeloid differentiation factor 88 (MyD88), TNF receptor-associated factor 6 (TRAF6), interleukin-1β (IL-1β), and IFNγ2 were all significantly enhanced after stimulation with r V.p FlaF in T. nigroviridis primary cells. In addition, the NO production and alkaline phosphatase (ALP) activity were significantly increased in the liver of T. nigroviridis after the r V.p FlaF challenge in vivo. Meanwhile, in Tn TLR5M-overexpressed HEK 293 T and Cos-7 cells, the luciferase activity of the nuclear factor-kappa B (NF-κB) reporter gene was significantly enhanced after r V.p FlaF stimulation, in a time- and dose-dependent manner. However, the other five flagellin components have no inflammation-inducing ability or the effect is relatively weak. Overall, our results suggested that r V.p FlaF activates the pro-inflammatory mediators including the release of NO and reactive oxygen species, as well as the expression of inflammatory cytokines IL-1β and IFNγ2, through the Tn TLR5M-NF-κB signaling pathway in T. nigroviridis. In conclusion, this study indicated that the r V.p FlaF has a significant role in inducing the inflammation of T. nigroviridis. • Vibrio parahaemolyticus flagellin induces the inflammatory response of Tetraodon nigroviridis • V.p FlaF has the ability to activate the T. nigroviridis immune response • V.p FlaF induces the inflammatory response through the TLR5M-MyD88-NF-κB signaling pathway. [ABSTRACT FROM AUTHOR]