Review: What innovations in pain measurement and control might be possible if we could quantify the neuroimmune synapse?

Abstract

It has taken more than 40 years for the fields of immunology and neuroscience to capture the potential impact of the mechanistic understanding of how an active immune signalling brain might function. These developments have grown an appreciation for the immunocompetent cells of the central nervous system and their key role in the health and disease of the brain and spinal cord. Moreover, the understanding of the bidirectional communication between the brain and the peripheral immune system has evolved to capture an understanding of how mood can alter immune function and vice versa. These concepts are rapidly evolving the field of psychiatry and medicine as a whole. However, the advances in human medicine have not been capitalised upon yet in animal husbandry practice. Of specific attention are the implications that these biological systems have for creating and maintaining heightened pain states. This review will outline the key concepts of brain–immune communication and the immediate opportunities targeting this biology can have for husbandry practices, with a specific focus on pain.

The Neuroimmune Interface and Chronic Pain Through the Lens of Production Animals

“…Assessing pain in animals, is notoriously difficult and frequently under recognized or overlooked. ( Grace et al, 2010 ; Hutchinson and Terry, 2019 ; Williams, 2019 ; Adcock, 2021 ; Steagall et al, 2021 ; Tschoner, 2021 ). This difficulty is often attributed to livestock being prey species which hide behavioral evidence of pain to avoid predation ( Williams, 2019 ; Cohen and Beths, 2020 ; Steagall et al, 2021 ).…”

“…The contribution of the immune system to the functioning of the central nervous system (CNS), known as central immune signaling, is vital and has become an area of growing interest, particularly in relation to the understanding of pain and chronic pain ( Grace et al, 2014 ; Hutchinson and Terry, 2019 ). Both preclinical rodent studies and clinical human studies have provided strong evidence that maladaptive chronic pain is driven by centrally mediated neuroimmune mechanisms ( Grace et al, 2021 ).…”

“…Objective and reliable measures of pain would present exciting opportunities to assess pain and address it where necessary. These measures would contribute significantly to developing new treatments and techniques to mitigate pain and improve our understanding of the experience of pain in animals ( Hutchinson and Terry, 2019 ). Not only would objective measures of pain greatly benefit animals, humans may also reap the rewards as livestock present a larger model of human disease ( Reddy et al, 2018 ; Herzberg and Bustamante, 2021 ).…”

“…The immune system is vital for regulating normal function of the nervous system and is also the first responder to damage within this system. Bi-directional communication between these systems contributes to biological coherence, explaining the influence of the immune system on behavior and vice-versa ( Hutchinson and Terry, 2019 ).…”

Evolving technological change in pork production supporting expectations of improved productivity, sustainability and flexibility

“…Finally, Hutchinson and Terry (2019) take us further afield into territory unfamiliar to many, but perhaps regrettably so. Progress in understanding the connection between the brain and the cells of the immune system is revealing great opportunities in human medicine, especially psychiatry.…”