Reflex Principles of Immunological Homeostasis

Abstract

The reasoning that neural reflexes maintain homeostasis in other body organs, and that the immune system is innervated, prompted a search for neural circuits that regulate innate and adaptive immunity. This elucidated the inflammatory reflex, a prototypical reflex circuit that maintains immunological homeostasis. Molecular products of infection or injury activate sensory neurons traveling to the brainstem in the vagus nerve. The arrival of these incoming signals generates action potentials that travel from the brainstem to the spleen and other organs. This culminates in T cell release of acetylcholine, which interacts with α7 nicotinic acetylcholine receptors (α7 nAChR) on immunocompetent cells to inhibit cytokine release in macrophages. Herein is reviewed the neurophysiological basis of reflexes that provide stability to the immune system, the neural- and receptor-dependent mechanisms, and the potential opportunities for developing novel therapeutic devices and drugs that target neural pathways to treat inflammatory diseases.

Neonicotinoid clothianidin adversely affects insect immunity and promotes replication of a viral pathogen in honey bees

“…immune systems in insects will likely promote a better understanding of the neural circuits involved in the regulation of immunity in animals (43,46), which appears to be an ancient homeostatic mechanism present also in distant evolutionary lineages such as nematodes (47,48).…”

Norepinephrine Controls Effector T Cell Differentiation through β2-Adrenergic Receptor–Mediated Inhibition of NF-κB and AP-1 in Dendritic Cells

“…t is well established that a cross-talk exists between the nervous and immune systems, with important implications for homeostasis maintenance (1,2). All immune organs receive innervation from tyrosine hydroxylase-positive fibers, suggesting that the release of neurotransmitters, such as norepinephrine (NE), by the sympathetic nervous system (SNS) could impact the function of immune cells (3,4).…”

Age-Related Changes of Vascular Bed Within Thymus Gland in Morphological Comparative Range of Vertebrate Animals (Chordata, Vertebrata)

“…Более развитое сосудистое русло теплокровных позвоночных, в сравнении с хо-лоднокровными представителями, не только увеличивает энергетическую емкость тканей тимуса, но и способствует существенному со-вершенствованию механизмов иммунной за-щиты [3]. Известно, что одной из возможных причин возрастной инволюции тимуса служат конкурентные взаимоотношения между иммуни-тетом и другими энергоемкими биологическими процессами, например размножением [6].…”

“…Причина подобной взаимозависимости заключена в том, что кровеносное русло является агентом, при непосредственном участии которого в тканях органа осуществляется целый ряд важнейших процессов [11]. Система кровоснабжения зани-мает центральное место в эндокринной регуля-ции иммуногенеза [3,5]. Отмечена зависимость обмена веществ и гомеостатических механизмов от характеристик микроциркуляции в тканях [7,9].…”