Induction of type I interferons in response to bacterial stimuli in large yellow croaker Larimichthys crocea

• Published in: Fish & shellfish immunology 2017-03, Vol.62, p.349-355
• Main Authors: Ding, Yang, Guan, Yanyun, Ao, Jingqun, Chen, Xinhua
• Format: Article
• Language: English
• Subjects: Aeromonas hydrophila - physiology; Animals; Bacterial stimulation; DNA, Bacterial - pharmacology; Expression modulation; Fish Diseases - genetics; Fish Diseases - immunology; Fish Diseases - microbiology; Fish Proteins - genetics; Fish Proteins - metabolism; Gram-Negative Bacterial Infections - genetics; Gram-Negative Bacterial Infections - immunology; Gram-Negative Bacterial Infections - microbiology; Gram-Negative Bacterial Infections - veterinary; Head Kidney - immunology; Head Kidney - metabolism; Head Kidney - microbiology; Interferon Type I - genetics; Interferon Type I - metabolism; Large yellow croaker Larimichthys crocea; Lipopolysaccharides - pharmacology; Peptidoglycan - pharmacology; Perciformes; Promoter activation; Promoter Regions, Genetic; Spleen - immunology; Spleen - metabolism; Spleen - microbiology; Type I interferons; Vibrio alginolyticus - physiology; Vibrio Infections - genetics; Vibrio Infections - immunology; Vibrio Infections - microbiology; Vibrio Infections - veterinary; Vibrio parahaemolyticus - physiology
• ISSN: 1050-4648; 1095-9947
• DOI: 10.1016/j.fsi.2017.01.027

In addition to the crucial roles in coordinating antiviral immune responses, type I interferons (IFNs) also play a role in the host immunity against bacterial pathogens. Our previous study identified two type I IFNs from large yellow croaker Larimichthys croaea(Lc), LcIFNd and LcIFNh, and showed their strong induction by poly(I:C) and antiviral activities. In the present study, both LcIFNd and LcIFNh were found to be rapidly induced in head kidney and spleen by mixed bacteria of Vibrio alginolyticus, Vibrio parahaemolyticus, and Aeromonas hydrophila. In the head kidney primary cells (HKCs), expression of these two LcIFN genes was increased by peptidoglycan (PGN) from Bacillus subtilis and lipopolysaccharide (LPS) from Escherichia coli. Consistently, Lc IFN-regulatory factor (LcIRF) 3 and LcIRF7, two key transcription factors of type I IFN expression, were also induced by these three bacteria, PGN, and LPS. These observations strongly suggested that large yellow croaker type I IFNs are involved in the immune response against bacterial infection. Luciferase assays showed that promoters of both LcIFNd and LcIFNh were activated by PGN, LPS, and genomic DNA of A. hydrophila, and A. hydrophila DNA was more potent than PGN and LPS in activating LcIFNd and LcIFNh promoters. Furthermore, the induction of LcIFNd promoter by these bacterial stimuli was further enhanced by the overexpression of LcIRF7 or LcIRF7 along with LcIRF3, while that of LcIFNh promoter was increased following the overexpression of LcIRF3 alone, suggesting that the induction of these two large yellow croaker IFNs by bacterial stimuli may be regulated via distinct manners. These results therefore revealed novel aspects of the functional regulation of teleost type I IFNs. •Large yellow croaker IFNd and IFNh could be rapidly induced by pathogenic bacteria in head kidney and spleen.•Expression of IFNd and IFNh was significantly increased by bacterial PGN and LPS in head kidney primary cells.•Promoters of IFNd and IFNh were activated by PGN, LPS, and bacterial DNA.•Induction of IFNd and IFNh were differentially regulated by IRF3 and/or IRF7 in response to bacterial stimuli.•IFNd and IFNh may be involved in the antibacterial immune response.