Changes in muscarinic cholinergic receptor expression in human peripheral blood lymphocytes in allergic rhinitis patients.
BACKGROUND
Parasympathetic nerves provide the dominant autonomic innervation of the upper and lower airways. They release acetylcholine that, activating post-junctional muscarinic receptors, causes bronchoconstriction, mucous secretion and vasodilation. Dysfunction of the upper and lower airways frequently coexist, and they appear to share key elements of pathogenesis.


OBJECTIVE
The present study has assessed the expression and pattern of cholinergic muscarinic receptor subtypes in peripheral blood lymphocytes harvested from allergic rhinitis patients with different degree of bronchial hyperresponsiveness detected by methacholine challenge test.


METHODS
Radioligand binding assay for determining the density of muscarinic cholinergic receptor subtypes; immunoblot analysis for assessing the characteristic of muscarinic cholinergic receptor subtype protein and immunocytochemical techniques for investigating the cellular localization of receptors.


RESULTS
An increased expression of M2 and M5 receptor proteins was observed in peripheral blood lymphocytes of allergic rhinitis patients in comparison with healthy control individuals. M3 receptor subtype decreased in allergic rhinitis patients with normal or mild responses to methacholine. A trend versus a return to normal value was found in moderate and severe responders. No changes of the M4 receptor subtype were found.


CONCLUSIONS
Increase in M2 receptor expression correlated with disease severity and bronchial hyperreactivity. Changes in muscarinic cholinergic receptor expression in allergic rhinitis underline a role of cholinergic system of immune cells in allergic airway disease.


CONCLUSIONS
Studies addressed to rhinitis and asthma have identified many similarities. Our results indicate that changes in peripheral blood lymphocyte muscarinic receptor expression may reflect the cholinergic involvement into allergic airway diseases.
Ricci
Alberto
A
Dipartimento di Scienze Cardiovascolari e Respiratorie, Università di Roma La Sapienza, Rome, Italy.
Mariotta
Salvatore
S
Amenta
Francesco
F
Tayebati
Seyed Khosrow
SK
Terzano
Claudio
C
D000328:Adult; D016535:Bronchial Hyperreactivity / Q000378:metabolism; D001985:Bronchial Provocation Tests; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D015151:Immunoblotting; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D011869:Radioligand Assay; D011976:Receptors, Muscarinic / Q000096:biosynthesis*; D012221:Rhinitis, Allergic, Perennial / Q000378:metabolism*; D012720:Severity of Illness Index
D011976:Receptors, Muscarinic