The vagus nerve as a modulator of intestinal inflammation

Noninvasive techniques for probing neurocircuitry and treating illness: vagus nerve stimulation (VNS), transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS)

Although the preceding chapters discuss much of the new knowledge of neurocircuitry of neuropsychiatric diseases, and an invasive approach to treatment, this chapter describes and reviews the noninvasive methods of testing circuit-based theories and treating neuropsychiatric diseases that do not involve implanting electrodes into the brain or on its surface. These techniques are transcranial magnetic stimulation, vagus nerve stimulation, and transcranial direct current stimulation. Two of these approaches have FDA approval as therapies.

Chemokine CXCL13 is essential for lymph node initiation and is induced by retinoic acid and neuronal stimulation

The location of embryonic lymph node development is determined by the initial clustering of lymphoid tissue-inducer (LTi) cells. Here we demonstrate that both the chemokine CXCL13 and the chemokine CCL21 attracted LTi cells at embryonic days 12.5-14.5 and that initial clustering depended exclusively on CXCL13. Retinoic acid (RA) induced early CXCL13 expression in stromal organizer cells independently of lymphotoxin signaling. Notably, neurons adjacent to the lymph node anlagen expressed enzymes essential for RA synthesis. Furthermore, stimulation of parasymphathetic neural output in adults led to RA receptor (RAR)-dependent induction of CXCL13 in the gut. Therefore, our data show that the initiation of lymph node development is controlled by RA-mediated expression of CXCL13 and suggest that RA may be provided by adjacent neurons.

Inflammatory cytokines decrease the expression of nicotinic acetylcholine receptor during the cell maturation

It is known that the nervous system significantly attenuates systemic inflammatory responses through the parasympathetic nervous system. Furthermore, it has been reported that the alpha 7 subunit of a nicotinic acetylcholine receptor is required for a cholinergic inhibition against cytokine synthesis in a macrophage. As antigen-presenting cells (APCs) play a central role in the generation of primary T cell responses and the maintenance of immunity, in this study, we investigated the expression level of nicotinic receptors of a p53-deficient APC cell line (JawsII) derived from a mouse bone marrow. We showed that stimulation of the JawsII cells with lipopolysaccharide (LPS) and tumor necrosis factor alpha (TNF-alpha) led increase of CD80 and CD86 expression while diminishment of the surface nicotinic receptor. On the other hand, stimulation of nicotinic receptor had no effect on these phenomena. Furthermore, we examined the ability of the cells to release cytokine when stimulated with both nicotine and LPS and showed that the stimulation with LPS augmented the secretion of IL-1a, IL-1b, IL-6, and TNF-alpha. These results suggested that nicotinic stimulation had no effect on the diminishment of alpha 7 nicotinic acetylcholine receptor on JawsII cells by LPS stimulation.

The cholinergic anti-inflammatory pathway: towards innovative treatment of rheumatoid arthritis

The efferent vagus nerve can regulate inflammation via its principal neurotransmitter acetylcholine (ACh), a concept referred to as the 'cholinergic anti-inflammatory pathway'. ACh interacts with members of the nicotinic acetylcholine receptor (nAChR) family, in particular with the alpha7 subunit (alpha7nAChR), which is expressed not only by neurons but also macrophages and other cells involved in the inflammatory response. In these inflammatory cells, the stimulation of alpha7nAChR by ACh and other alpha7nAChR-specific agonists suppresses the release of proinflammatory cytokines. Recent work has suggested that alpha7nAChR could represent a new target for the treatment of rheumatic diseases. In this Perspective, we describe the cholinergic anti-inflammatory pathway and the therapeutic potential of modulating this pathway in rheumatoid arthritis.

Vagus nerve stimulation may be used in the therapy of myocarditis

Although a large number of different causes have been identified as leading to myocarditis, inflammation plays a pivotal role in its pathological process. No specific methods are available in the therapy of myocarditis except symptomatic treatment. Vagus nerve stimulation has been found to lower the heart rate and recover the normal heart rhythm which may relieve the cardiac symptoms in myocarditis. Furthermore, the acetylcholine that secreted by vagus nerve stimulation was found to inhibit the production of such inflammatory cytokines as tumor necrosis factor-alpha (TNF-alpha), interleukin 1beta (IL-1beta). Based on the above, we hypothesized that vagus nerve stimulation can be used in the therapy of myocarditis and lead to relief of symptoms and inhibition of inflammatory process which may kill two birds with one stone.