Interaction between the hypothalamus and the immune system

Abstract

What is the topic of this review? Both branches of the autonomic nervous system are involved in the regulation of the inflammatory response. We explore how the hypothalamus may influence this process. What advances does it highlight? We analyse how a lipopolysaccharide signal is transmitted to the brain and which areas participate in the response of the brain to lipopolysaccharide. Recent studies show that the hypothalamus can influence the inflammatory response by modifying the autonomic output. The biological clock, the suprachiasmatic nucleus, is integrated into this circuit, putting a time stamp on the intensity of the inflammatory response. The brain is responsible for maintaining homeostasis of the organism, constantly adjusting its output via hormones and the autonomic nervous system to reach an optimal setting in every compartment of the body. Also, the immune system is under strong control of the brain. Apart from the conventional systemic responses evoked by the brain during inflammation, such as hypothalamic-pituitary-adrenal axis activation and the induction of sickness behaviour, the autonomic nervous system is now recognized to exert regulatory effects on the inflammatory response. Both branches of the autonomic nervous system are proposed to influence the inflammatory process. Here, we focus on those areas of the brain that might be involved in sensing inflammatory stimuli, followed by how that sensing could change the output of the autonomic nervous system in order to regulate the inflammatory response. Finally, we will discuss how the defenses of the body against a lipopolysaccharide challenge are organized by the hypothalamus.

Physiological and pathophysiological roles of hypothalamic astrocytes in metabolism

“…In both humans and animal models, obesity and type 2 diabetes are associated with low grade systemic inflammation and the hypothalamus may also be a target for cytokines produced systemically . Indeed, i.c.v.…”

“…In both humans and animal models, obesity and type 2 diabetes are associated with low grade systemic inflammation 89 and the hypothalamus may also be a target for cytokines produced systemically. 90 Indeed, i.c.v. injections of TNF-α reduce the effects of anorexigenic hormones 91 leading to an increase in insulin secretion by the pancreas and plasma insulin levels.…”

Monomeric C-Reactive Protein Aggravates Secondary Degeneration after Intracerebral Haemorrhagic Stroke and May Function as a Sensor for Systemic Inflammation

“…In the same context, the immune response evokes brain changes for organizing physiological and behavioural adaptations after an immune challenge. The brain structures involved in the induction of this inflammatory response behaviour are not well established, but there is evidence supporting the participation of the hypothalamus in the regulation of the inflammatory response [ 11 ]. A major function of the hypothalamus is to integrate sensory information and elicit adaptive changes in physiology and behaviour to achieve homeostasis [ 12 ].…”

Altered hypothalamus functional connectivity with limbic system in fibromyalgia and the modulation effect of intervention

“…The first aim of this study is to investigate alterations in hypothalamus rsFC between fibromyalgia patients and healthy controls. We focused on the hypothalamus because it is a functionally diverse region of the brain that regulates vital bodily functions such as stress, immune responses, and autonomic and endocrine functions [23,24] . Literature suggests that hypothalamic subregions are functionally connected to their associated neural networks (limbic system) for the integration of sensory and affective information.…”

“…Literature suggests that hypothalamic subregions are functionally connected to their associated neural networks (limbic system) for the integration of sensory and affective information. As the initial point of hypothalamic-pituitary-adrenal axis activation, the hypothalamus has been found to exert regulatory effects on the inflammatory response [23,25] , which may play an important role in the pathophysiology of fibromyalgia [26] . Brain imaging studies suggest that it may also be involved in chronic pain.…”