Brainstem processing of cough sensory inputs in chronic cough hypersensitivity.

BACKGROUND

Chronic cough is a prevalent and difficult to treat condition often accompanied by cough hypersensitivity, characterised by cough triggered from exposure to low level sensory stimuli. The mechanisms underlying cough hypersensitivity may involve alterations in airway sensory nerve responsivity to tussive stimuli which would be accompanied by alterations in stimulus-induced brainstem activation, measurable with functional magnetic resonance imaging (fMRI).

METHODS

We investigated brainstem responses during inhalation of capsaicin and adenosine triphosphate (ATP) in 29 participants with chronic cough and 29 age- and sex-matched controls. Psychophysical testing was performed to evaluate individual sensitivities to inhaled stimuli and fMRI was used to compare neural activation in participants with cough and control participants while inhaling stimulus concentrations that evoked equivalent levels of urge-to-cough sensation.

FINDINGS

Participants with chronic cough were significantly more sensitive to inhaled capsaicin and ATP and showed a change in relationship between urge-to-cough perception and cough induction. When urge-to-cough levels were matched, participants with chronic cough displayed significantly less neural activation in medullary regions known to integrate airway sensory inputs. By contrast, neural activations did not differ significantly between the two groups in cortical brain regions known to encode cough sensations whereas activation in a midbrain region of participants with chronic cough was significantly increased compared to controls.

INTERPRETATION

Cough hypersensitivity in some patients may occur in brain circuits above the level of the medulla, perhaps involving midbrain regions that amplify ascending sensory signals or change the efficacy of central inhibitory control systems that ordinarily serve to filter sensory inputs.

FUNDING

Supported in part by a research grant from Investigator-Initiated Studies Program of Merck Sharp & Dohme Pty Ltd. The opinions expressed in this paper are those of the authors and do not necessarily represent those of Merck Sharp & Dohme (Australia) Pty Ltd.

Informations de copyright

Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.

Déclaration de conflit d'intérêts

Declaration of interests SBM reports receiving grants from the National Health and Medical Research Council (NHMRC) of Australia and the Australian Research Council (ARC), Merck, Bellus Health and Reckitt Benkiser, and remuneration for consultancy from Merck, Trevi Therapeutics, Reckitt Benkiser and Nerre Therapeutics, has served on advisory committees for Reckitt Benkiser and has received payment from Reckitt Benkiser for assistance with manuscript writing. KFC reports research grants from Merck and GSK, remuneration for lectures from Novartis and AstraZeneca; has served on advisory boards for Roche, Merck, Reckitt Benckiser, and Shionogi & Co., Ltd., and a Data Safety Monitoring Board for Nocion. LMG reports research grants from Bayer AG, Bellus Health, Chiesi, Merck, and Shionogi, remuneration for lectures from Bayer AG, Bellus Health, Chiesi, GlaxoSmithKline, Merck, and Shionogi, remuneration for consultancy from Bayer AG, Bellus Health, Chiesi, Merck, NeRRe Therapeutics, Nocion Therapeutics, and Shionogi, and has served on advisory committees for Applied Clinical Intelligence, Bayer AG, Bellus Health, Chiesi, Merck, NeRRe Therapeutics, Nocion Therapeutics, and Shionogi and on a Data and Safety Monitoring Board for Bayer AG. All other authors declare no relevant conflict of interest.