Sensory nerves in the airways release inflammatory neuropeptides like substance P and CGRP that amplify airway inflammation in animal models, but their role in human asthma and COPD remains unproven.
Animal vs. human gapNeurogenic airway inflammation is well-established in rodents but clinical trials blocking neuropeptides in human asthma have not been encouraging
What the researchers found
Neuropeptides — particularly tachykinins (substance P, neurokinin A) and calcitonin gene-related peptide (CGRP) — are released from sensory nerves in the airways through axon reflexes and local nerve activation. In rodent models, this neurogenic inflammation clearly contributes to responses against allergens, infections, and irritants. However, direct evidence for sensory neuropeptide involvement in human airway disease is lacking, and initial clinical studies using strategies to block neurogenic inflammation have not shown encouraging results.
Why it matters
Asthma and COPD affect hundreds of millions of people worldwide, and many patients remain poorly controlled on existing therapies. If neuropeptide-driven inflammation contributes to these diseases in humans, blocking it could provide new treatment options. This review is important because it honestly assesses both the promise of this pathway and the gap between compelling animal data and disappointing human results.
How the study worked
This is a narrative review by P.J. Barnes examining the evidence for neurogenic inflammation in airways across species. It covers in vitro and in vivo animal studies, human tissue data, and early clinical trial results targeting neuropeptide pathways in airway disease.
What this study cannot tell us
This is a 2001 review and reflects the state of knowledge at that time. The author notes that direct evidence for neuropeptide involvement in human airway disease was limited and clinical trials had been negative. Subsequent research has provided some additional insights but the fundamental translation gap from rodent to human airway neurogenic inflammation persists.
How to read the evidence
This is a narrative review summarizing evidence from animal studies, human tissue experiments, and early clinical trials. It represents expert synthesis rather than new primary data.
When this study was published
Published in 2001 by a leading respiratory pharmacologist. While older, it provides foundational context for understanding neuropeptide involvement in airway disease. The species-translation challenge it describes remains relevant today.
The bigger picture
Neurogenic inflammation represents a direct connection between the nervous system and immune-mediated airway disease. Understanding this neuro-immune crosstalk through neuropeptides has become increasingly important as the field recognizes that asthma and COPD are not purely immune-driven conditions. The challenges described in this review — the species differences between rodents and humans — remain relevant to current neuropeptide research.
Questions still open
- Would targeting neuropeptide pathways in severe asthma or COPD (rather than mild disease) reveal a meaningful clinical effect?
- Do CGRP-targeting therapies developed for migraine have any measurable effects on airway inflammation?
- Why is neurogenic inflammation so prominent in rodent airways but apparently less important in human airways?
Common questions
What is neurogenic inflammation in the airways?
Why haven't neuropeptide-blocking treatments worked for asthma?
Read the original research
Neurogenic inflammation in the airways.
Respiration physiology, 125(1-2), 145-54
Citation
Barnes, P J. (2001). Neurogenic inflammation in the airways.. Respiration physiology, 125(1-2), 145-54.