Insights into molecular profiles and genomic evolution of an IRAK4 homolog from rock bream (Oplegnathus fasciatus): Immunogen- and pathogen-induced transcriptional expression

Toll-like receptor 4 (TLR4) plays a critical role in host immunity against Gram-negative bacteria. It transduces signals through two distinct TIR-domain-containing adaptors, MyD88 and TRIF, which function at the plasma membrane and endosomes, respectively. Using zebrafish Aeromonas hydrophila infection model, we demonstrate that synchronization of MyD88 and TRIF dependent pathways is critical for determining the fate of infection. Zebrafish were infected with A. hydrophila, and bacterial recovery studies suggested its effective persistence inside the host. Histopathological assessment elucidates that A. hydrophila did not provoke inflammatory responses in the spleen. Immunofluorescence revealed the presence of TLR4-bound A. hydrophila on the plasma membrane at 3 h post-infection (p.i.), and inside endosomes 1 day p.i. Quantitative PCR studies suggest that TLR4 activates the downstream pathway of MyD88-IRAK4 axis at early stages followed by a shift to TRIF-TRAF6 axis at late stages of infection coupled with fold increase in NFκB. Our results implicated the involvement of p110δ isoform of PI(3)Kinase in this transition. Coupled to this, we noted that the TLR4-TRIF-NFκB axis prompted burgeoned secretion of anti-inflammatory cytokines. We observed that A. hydrophila inhibits endosome maturation and escapes to cytoplasm. Significant downregulation of cytosolic-NLR receptors further suggested that A. hydrophila represses pro-inflammatory responses in cytosol aiding its persistence. Our findings suggest a novel role of 'TLR4 topology' in A. hydrophila-induced pathogenesis. We propose that A. hydrophila manipulates translocation of TLR4 and migrates to endosome, where it triggers TRIF-dependent anti-inflammatory responses, interferes with endosomal maturation and escapes to cytosol. Inside the cytosol, A. hydrophila avoids detection by suppressing NLRs, facilitating its survival and ensuing pathogenesis.

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“…Upregulation of IRAK4 and TRAF6 has been reported in fish against several bacteria including A. hydrophila . 30 , 44 , 45 …”

Section: Discussionmentioning

confidence: 99%

Aeromonas hydrophila utilizes TLR4 topology for synchronous activation of MyD88 and TRIF to orchestrate anti-inflammatory responses in zebrafish

et al. 2017

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“…was substantial upregulation in Oplegnathus fasciatus and Danio rerio after challenge of E. tarda, respectively (Phelan et al, 2005;Umasuthan et al, 2015). Furthermore, TAK1 plays a major role in NF-κB, JNK, and p38 activation mediated by IL-1 in human and mammals (Wang, Peng, et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

“…A similar result was shown in golden pompano challenged to Vibrio alginilyticus and stimulated to polyI:C, IRAK4 was also significant increased (Qi et al, 2017). Moreover, the mRNA expression of IRAK4 was substantial upregulation in Oplegnathus fasciatus and Danio rerio after challenge of E. tarda , respectively (Phelan et al, 2005; Umasuthan et al, 2015). Furthermore, TAK1 plays a major role in NF‐κB, JNK, and p38 activation mediated by IL‐1 in human and mammals (Wang, Peng, et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

Effects of TLR2/4 signalling pathway in western mosquitofish (Gambusia affinis) after Edwardsiella tarda infection

Wang

Chen

Tang

et al. 2023

Journal of Fish Diseases

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Edwardsiella tarda is an Enterobacteriaceae (Leung et al., 2019) a common pathogen of fish that is widely distributed in freshwater and marine (Park et al., 2012). Edwardsiella tarda, which cause edwardsiellosis in fish, and E. tarda is a zoonotic agent that could causes acute gastroenteritis in humans (Bockemühl et al., 1971). Edwardsiella piscicida is the member of Edwardsiella family, which is closely related with E. tarda and can also infect human and other animals by the food chain (Vayssier-Taussat et al., 2014). Edwardsiella could cause skin and soft tissue infection to human by the aquatic-based infections (Vasagar et al., 2018). Edwardsiella tarda is commonly associated with systemic disease and could cause outbreaks disease in fish. Edwardsiella tarda caused Lates calcarifer erythema and/or on the ventrum and gastrointestine tract, haemorrhage on the fin/ oral and wall at necropsy, gill pallor (Loch et al., 2017). Nowadays, E. tarda as a zoonotic bacteria control is an urgent task with the scale of aquaculture expanding. Antibiotics are still the main treatment for bacterial infections (Dong et al., 2018). But antibiotic-resistant pathogens have increased due to the irregular use and abuse of antibiotics (Moreno et al., 2006).The toll like receptor (TLR) 4 is the first member of the TLR family to be identified as a pattern recognition receptor pathogen. TLR4 signals are involved in the innate immune responses of most microorganisms, including gram bacteria, mycobacteria, spirochetes, yeasts, and some viruses (e. g. human respiratory syncytial virus and breast tumour viruses) (Spanou et al., 2017). TLR2 is known for a receptor that can recognize multiple bacterial and fungal cell wall

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“…We have previously identified and reported the molecular properties of these CXCL8-receptors from O. fasciatus [ 10 ]. With the objective of exploring the immune signaling mechanisms in fish, we have also previously characterized several immune genes associated with toll-like receptor (TLR) signaling in O. fasciatus [ 10 , 48 , 49 , 60 , 61 , 62 , 63 ]. In this study, two cxcl8 homologs, Ofcxcl8-L1 and OfCXCL8-L3 , were isolated from O. fasciatus , in addition to the sequences available in GenBank (i.e., AB703273 and ADK35757), and cloned.…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2020

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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.

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Insights into molecular profiles and genomic evolution of an IRAK4 homolog from rock bream (Oplegnathus fasciatus): Immunogen- and pathogen-induced transcriptional expression

Cited by 15 publications

References 49 publications

Aeromonas hydrophila utilizes TLR4 topology for synchronous activation of MyD88 and TRIF to orchestrate anti-inflammatory responses in zebrafish

Aeromonas hydrophila utilizes TLR4 topology for synchronous activation of MyD88 and TRIF to orchestrate anti-inflammatory responses in zebrafish

Effects of TLR2/4 signalling pathway in western mosquitofish (Gambusia affinis) after Edwardsiella tarda infection

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

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