Table 3.

Neuropeptides released by vagus efferents (i-NANC, e-NANC) and retrogradely released by afferents (capsaicin C-fibers) contributing to asthma symptoms. A description of the action of a particular peptide and its receptor involved.

Peptide (Sequence)		Asthma Suppression	Asthma Promoting	Receptors	References
Vasoactive intestinal polypeptide (VIP) (HSDAVFTDNYTRLRKQMAVKKYLNSILN)		Mice lacking the VIP gene exhibited spontaneous asthma features including AHR			[95]
		Bronchodilatation		VAPC2	[87,94]
TACHYKININS	Substance P (SP) (RPKPQQFFGLM)		↑ mucus secretion ↑ development of AHR↑ recruitment of airwayneutrophils, ↑ degranulation of mast cells	NK1	[100,101,119,122]
	Neurokinin A (NKA) (HKTDSFVGLM)		↑ bronchoconstriction ↑ development of AHR	NK2	[102,119,123]
	HK-1 (RSRTRQFYGLM)		↑degranulation of mast cells	NK-1, MRGPRX2	[122]
Calcitonin gene–related peptide (CGRP) (ACDTATCVTHRLAGLLSRSGGVVKNNFVPTNVGSKAF)			↑ vasodilatation, ↑ mucus secretion and edema ↑ trachea muscle contractions to capsaicin and electrical field	RAMP 1	[5,128,129,130,131,132]
		↓ AHR and eosinophilic inflammation			[133]