Possible implication of vagal nerve stimulation for treating refractory psoriasis: Possível implicação da estimulação do nervo vagal para o tratamento da psoríase refratária

Abstract

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Psoriasis is a chronic, relapsing, immune-based skin disease that affects an estimated 1-3% of the world’s population.1 There is no consensus regarding the exact etiology of psoriasis; among several postulated pathophysiological causes, excessive activity of T cell-mediated immune response, and T-helper (Th) in particular, is the most accepted theory. This is supported by increased levels of pro-inflammatory cytokines, especially tumor necrosis factor (TNF-α) in the serum, skin lesions and joints of these patients.2^,^3

Although inhibitors of tumor necrosis factor (TNF-α) have been shown to be effective for treating refractory psoriasis,3^,^4 there are no therapies providing long-lasting remission for these patients.

Since Tracey5 proposed the so-called inflammatory reflex, the data now emerging has been elucidating and supporting the existence of a neural circuit that modulates immune response. This cholinergic anti-inflammatory pathway originates from efferent vagal fibers. It seems that inhibition of TNF-α production in the spleen following vagal nerve stimulation occurs through acetylcholine signaling via the α7 nicotinic acetylcholine receptor that is expressed on cytokine-producing macrophages.5^,^6 This signal is relayed through an acetylcholine-producing, memory phenotype T cell population that has been identified in mice, which is necessary for inhibition of cytokine production through vagus nerve stimulation.7

Immunomodulation via vagal nerve stimulation has been implicated in the treatment of other immune disorders involving the TNF-α pathway, such as inflammatory bowel disease.8 In this regard, we support the hypothesis that vagal nerve stimulation may prove useful for treating refractory psoriasis and psoriatic arthritis through its cholinergic anti-inflammatory effects, by means of modulating TNF-α production.9

This novel idea encourages interest in conducting a double-blind case-control study to investigate the possible role of vagal nerve stimulation in treating psoriasis and psoriatic arthritis.