A novel tumor necrosis factor in the Pacific oyster Crassostrea gigas mediates the antibacterial response by triggering the synthesis of lysozyme and nitric oxide. Issue 98 (March 2020)

• Record Type: Journal Article
• Authors: Zheng, Yan; Liu, Zhaoqun; Wang, Lingling; Li, Meijia; Zhang, Yukun; Zong, Yanan; Li, Yinan; Song, Linsheng
• Is Part Of: Fish & shellfish immunology. Issue 98(2020)
• Page Start: 334
• Page End: 341
• Publication Date: 2020-03
• Subjects: Tumor necrosis factor -- Antibacterial immunomodulation -- Inhibition of A549 cell growth -- Crassostrea gigas; Fishes -- Immunology -- Periodicals; Shellfish -- Immunology -- Periodicals; Poissons -- Immunologie -- Périodiques; Crustacés -- Immunologie -- Périodiques; 571.9617
• DOI: 10.1016/j.fsi.2019.12.073
• Languages: English
• ISSNs: 1050-4648

Abstract

Abstract: Tumor necrosis factors (TNFs) are a group of multifunctional inflammatory cytokines involved in various pathological and immune processes. Recently, a few primitive TNFs have been characterized from molluscs, which play important roles in modulating cell apoptosis, phagocytosis and production of immune-related enzymes. In the present study, a novel TNF (named as Cg TNF-2) with the activity to mediate antibacterial response was identified from the Pacific oyster Crassostrea gigas . The open reading frame of Cg TNF-2 was of 783 bp encoding a putative polypeptide of 261 amino acids with a typical TNF domain. The deduced amino acid sequence of Cg TNF-2 shared high identity with that of TNFs previously identified from other molluscs, such as 96.1% identity with that in oyster C. hongkongensis, 33.7% identity with that in scallop Mizuhopecten yessoensis and 33.0% identity with Cg TNF-1 in oyster C. gigas . There were two distinct TNF branches of vertebrate and invertebrate in the phylogenetic tree, and Cg TNF-2 was firstly clustered with TNF-14 from C. hongkongensis, and then clustered with other molluscan TNFs. The mRNA transcripts of Cg TNF-2 were widely expressed in various oyster tissues, with the highest expression level in hemocytes. The expression level of Cg TNF-2 increased significantly at 6 h (2.45-fold and 6.20-fold, respectively, p < 0.05) after peptidoglycan and lipopolysaccharides treatments, and peaked at 12 h (31.86-fold and 7.90-fold, respectively, p < 0.05). The recombinant protein of Cg TNF-2 (r Cg TNF-2) inhibited the growth of human alveolar basal epithelial (A549) cells at a concentration of 800 ng/mL. After the oysters received an injection of r Cg TNF-2, the serum from those oysters exhibited significantly higher antibacterial activity compared to that from control group, evidenced by inhibiting the growth of Vibrio splendidus . Moreover, the lysozyme activity as well as the contents of nitric oxide in the oyster serum also increased significantly. The above results collectively suggested that Cg TNF-2 was a novel member of bivalve TNF-α family, which could prompt the antibacterial activity by inducing the lysozyme activity and the production of nitric oxide in the innate immune response of oyster. Highlights: A novel TNF ( Cg TNF-2) was identified from C. gigas and belonged to TNF-α family. Cg TNF-2 was highly expressed in hemocytes and could be induced by LPS and PGN. Cg TNF-2 regulated the antibacterial response by lysozyme activity and synthesis of NO.