The neuroendocrine immunomodulatory axis-like pathway mediated by circulating haemocytes in pacific oyster Crassostrea gigas.

Zhaoqun Liu,Linsheng Song,Zhi Zhou,Qiufen Jiang,Lingling Wang,Limei Qiu,Qilin Yi

doi:10.1098/rsob.160289

Abstract

The neuroendocrine-immune (NEI) regulatory network is a complex system, which plays an indispensable role in the immunity of host. In this study, a neuroendocrine immunomodulatory axis (NIA)-like pathway mediated by the nervous system and haemocytes was characterized in the oyster Crassostrea gigas. Once invaded pathogen was recognized by the host, the nervous system would temporally release neurotransmitters to modulate the immune response. Instead of acting passively, oyster haemocytes were able to mediate neuronal immunomodulation promptly by controlling the expression of specific neurotransmitter receptors on cell surface and modulating their binding sensitivities, thus regulating intracellular concentration of Ca2+. This neural immunomodulation mediated by the nervous system and haemocytes could influence cellular immunity in oyster by affecting mRNA expression level of TNF genes, and humoral immunity by affecting the activities of key immune-related enzymes. In summary, though simple in structure, the ‘nervous-haemocyte’ NIA-like pathway regulates both cellular and humoral immunity in oyster, meaning a world to the effective immune regulation of the NEI network.

Highlights

A neuroendocrine-immune regulatory (NEI) network is proposed to bring the self-regulated immune system into conformity with other body systems
NE exerted various effects on nitric oxide synthase (NOS) activities and NO production at different immune stages via a novel a/b-adrenoceptor-cAMP/Ca2þ regulatory pattern [32,33,34]. These findings further suggested that the ‘nervous-haemocyte’ neuroendocrine immunomodulatory axis (NIA)-like pathway based on the binding of neurotransmitters or hormones to their receptors on haemocyte surface might be far more 2 important for the invertebrates than we have learned
Communication between the neuroendocrine and immune systems is of great importance for the maintenance of homeostasis and body integrity in both vertebrates and invertebrates [38,39]

Summary

Introduction

A neuroendocrine-immune regulatory (NEI) network is proposed to bring the self-regulated immune system into conformity with other body systems. This hypothesis is based on the existence of reciprocal interactions between immune and neuroendocrine systems in the host [1]. In this network, the nervous system regulates immune responses through humoral and neuronal routes [2] by activating the immune system to synthesize cytokines and immune-related enzymes to modulate immune responses [3,4]. Neuroendocrine responses controls inflammation at a systemic level through the hypothalamic–pituitary–adrenal (HPA), hypothalamic–pituitary–gonadal (HPG) and hypothalamic–pituitary–thyroid hormone (HPT) axes, in which the

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