Influence of Hyperproteinemia on Insect Innate Immune Function of the Circulatory System in <i>Bombyx mori</i>

• Main Authors: Yong-Feng Wang, Guang Wang, Jiang-Lan Li, Ya-Xin Qu, Xin-Yin Liang, Xue-Dong Chen, Yang-Hu Sima, Shi-Qing Xu
• Format: Article
• Language: English
• Published: MDPI AG 2021-02-01
• Series: Biology
• Subjects: <i>Bombyx mori</i>; innate immunity; melanization; NF-κB signaling; plasma protein concentration (PPC)
• Online Access: https://www.mdpi.com/2079-7737/10/2/112

Metabolic disorders of the circulatory system of animals (e.g., hyperglycemia and hyperlipidemia) can significantly affect immune function; however, since there is currently no reliable animal model for hyperproteinemia, its effects on immunity remain unclear. In this study, we established an animal model for hyperproteinemia in an invertebrate silkworm model, with a controllable plasma protein concentration (PPC) and no primary disease effects. We evaluated the influence of hyperproteinemia on innate immunity. The results showed that high PPC enhanced hemolymph phagocytosis via inducing a rapid increase in granulocytes. Moreover, while oenocytoids increased, the plasmacytes quickly dwindled. High PPC inhibited hemolymph melanization due to decreased phenoloxidase (PO) activity in the hemolymph via inhibiting the expression of the prophenoloxidase-encoding genes, <i>PPO1</i> and <i>PPO2</i>. High PPC upregulated the gene expression of antimicrobial peptides via differential activation of the Toll and Imd signaling pathways associated with NF-κB signaling, followed by an induction of inconsistent antibacterial activity towards Gram-positive and Gram-negative bacteria in an animal model of high PPC. Therefore, high PPC has multiple significant effects on the innate immune function of the silkworm circulatory system.