Greater potency of adipocytes compared with preadipocytes under lipopolysaccharide exposure in grass carp Ctenopharyngodon idella

Excessive body fat is a chronic inflammatory disorder. In this process, white adipose tissue (WAT) performs immune activities because of the dysregulated expression of adipokines. Excessive fat is accumulated in farmed fish, thereby threatening fish health. Studies have shown that adipose tissue is also an active immune organ in fish, capable of participating in and influencing immune responses. Adipocytes are the main cellular component of adipose tissue; however, little is known about the relationship between adipocyte and inflammation in fish. In this study, we analyzed transcriptome changes during adipogenesis in the primary culture of grass carp adipocytes using bioinformatics. The results showed that inflammatory signaling pathway may be activated during grass carp adipocyte differentiation, such as NFκB signaling pathway, Toll-like receptor signaling pathway and Adipocytokine signaling pathway, indicating that grass carp adipocytes have immune activities. Exposure to LPS induced expression of adipokines genes in adipocytes and preadipocytes, including NF-kB, IL-6, MCP-1 and TNFα, suggesting that preadipocytes and adipocytes both have immune response and the immune activity is conserved in vertebrates white adipocytes. Further study found that these immune marker genes were higher expressed in adipocytes compared with preadipocytes in LPS-induced inflammation. In summary, adipocyte should be considered as an active immune site in fish. Adipocytes have greater potency compared with preadipocytes in LPS-induced inflammation. This study indicated that adipocytes and preadipocytes may have different contribution in inflammation.