An update on the asthma-rhinitis link
An update on the asthma-rhinitis link
Purpose of Review: For the present article we collected and reviewed the more relevant experimental results concerning the asthma-rhinitis link in allergic diseases, published since January 2002.
Recent Findings: During the last 2 years, particular attention has been devoted to the behaviour of the immune response in the two compartments of the airways. The recent experimental data, mainly obtained with specific nasal or bronchial allergen challenges, have confirmed that the link between the nose and the bronchi is bidirectional, and that a systemic cross-talk occurs. Furthermore, the pathogenic role of paranasal sinus infections in respiratory allergy has been better elucidated. It was shown that, in sinusitis, a T helper type 2 polarization exists, which can be reverted by proper therapy. On the other hand, despite the abundant experimental evidence, our view of the united airways is still not complete, and several points need to be developed.
Summary: The new findings on the asthma-rhinitis link have confirmed the current pathogenic view of respiratory allergy. These findings have important implications from a therapeutic point of view, and therefore encourage and promote the search for novel integrated treatment strategies.
The link existing between upper and lower respiratory airways was repeatedly observed in the past, and has led during the last years to the concept of the 'united airways disease' or 'allergic rhinobronchitis'. The clinical, functional, pathogenic, and immunological unity of the upper and lower respiratory tract has been further confirmed experimentally during the last 2 years, as testified by the large number of articles published on the subject. Moreover this concept has been acknowledged in recent official documents.
The overall pathogenic view of respiratory allergy has deeply changed and evolved over the last 10 years, and the relationship existing between rhinitis and asthma (upper and lower respiratory airways) has become clearer. These changes were mainly due to the availability of several powerful procedures: (1) the possibility of investigating in more and more detail the immunological mechanisms; (2) the epidemiological studies conducted on large patient populations; (3) the clinical investigations on the mechanisms of drug actions.
Some facts have been ascertained as experimental evidence: the epidemiological association between rhinitis and asthma, the common immunological behaviour of the upper and lower respiratory tract, the involvement of paranasal sinuses in asthma and rhinitis, and the possibility of modulating the immune and clinical response in patients with rhinitis in order to prevent the development of asthma.
All the aforementioned experimental facts have clarified the concept that upper and lower respiratory airways behave as a single entity, at least from an immunological and clinical point of view. The existence of the 'united airways' was first deduced from epidemiological studies, which indicated and confirmed that rhinitis and asthma are strictly linked. Several cross-sectional studies clearly showed the association between rhinitis and asthma: up to 50% of patients with rhinitis have asthma, and rhinitis occurs in up to 80% of patients with asthma. This fact was confirmed in a questionnaire-based study carried out in adolescents, for which more than 80% of asthmatic subjects reported to also have rhinitis. In addition, another recent study, performed in young conscripts, reported that more than 70% of rhinitics had also asthma. Similar observations come out from longitudinal and follow-up studies, in which it was shown that rhinitis usually precedes and is a risk factor for asthma, even independently of the atopic status. At present, we have available numerous clinical and immunological data; and many pathogenic hypotheses on the functional link between rhinitis and asthma can be made (Fig. 1).
(Enlarge Image)
Summary of the hypotheses explaining the links between rhinitis and asthma
Purpose of Review: For the present article we collected and reviewed the more relevant experimental results concerning the asthma-rhinitis link in allergic diseases, published since January 2002.
Recent Findings: During the last 2 years, particular attention has been devoted to the behaviour of the immune response in the two compartments of the airways. The recent experimental data, mainly obtained with specific nasal or bronchial allergen challenges, have confirmed that the link between the nose and the bronchi is bidirectional, and that a systemic cross-talk occurs. Furthermore, the pathogenic role of paranasal sinus infections in respiratory allergy has been better elucidated. It was shown that, in sinusitis, a T helper type 2 polarization exists, which can be reverted by proper therapy. On the other hand, despite the abundant experimental evidence, our view of the united airways is still not complete, and several points need to be developed.
Summary: The new findings on the asthma-rhinitis link have confirmed the current pathogenic view of respiratory allergy. These findings have important implications from a therapeutic point of view, and therefore encourage and promote the search for novel integrated treatment strategies.
The link existing between upper and lower respiratory airways was repeatedly observed in the past, and has led during the last years to the concept of the 'united airways disease' or 'allergic rhinobronchitis'. The clinical, functional, pathogenic, and immunological unity of the upper and lower respiratory tract has been further confirmed experimentally during the last 2 years, as testified by the large number of articles published on the subject. Moreover this concept has been acknowledged in recent official documents.
The overall pathogenic view of respiratory allergy has deeply changed and evolved over the last 10 years, and the relationship existing between rhinitis and asthma (upper and lower respiratory airways) has become clearer. These changes were mainly due to the availability of several powerful procedures: (1) the possibility of investigating in more and more detail the immunological mechanisms; (2) the epidemiological studies conducted on large patient populations; (3) the clinical investigations on the mechanisms of drug actions.
Some facts have been ascertained as experimental evidence: the epidemiological association between rhinitis and asthma, the common immunological behaviour of the upper and lower respiratory tract, the involvement of paranasal sinuses in asthma and rhinitis, and the possibility of modulating the immune and clinical response in patients with rhinitis in order to prevent the development of asthma.
All the aforementioned experimental facts have clarified the concept that upper and lower respiratory airways behave as a single entity, at least from an immunological and clinical point of view. The existence of the 'united airways' was first deduced from epidemiological studies, which indicated and confirmed that rhinitis and asthma are strictly linked. Several cross-sectional studies clearly showed the association between rhinitis and asthma: up to 50% of patients with rhinitis have asthma, and rhinitis occurs in up to 80% of patients with asthma. This fact was confirmed in a questionnaire-based study carried out in adolescents, for which more than 80% of asthmatic subjects reported to also have rhinitis. In addition, another recent study, performed in young conscripts, reported that more than 70% of rhinitics had also asthma. Similar observations come out from longitudinal and follow-up studies, in which it was shown that rhinitis usually precedes and is a risk factor for asthma, even independently of the atopic status. At present, we have available numerous clinical and immunological data; and many pathogenic hypotheses on the functional link between rhinitis and asthma can be made (Fig. 1).
(Enlarge Image)
Summary of the hypotheses explaining the links between rhinitis and asthma
