Adrenomedullin level in the nasal discharge from allergic rhinitis cohort

Adrenomedullin (AM) is a potent hypotensive and vasodilatory peptide. AM may exert protective actions against the development of many diseases by modulating the blood circulation and body fluid balance. In addition to these functions, it has recently been reported to play important roles in the development of allergy and infections. The purpose of the present study was to demonstrate the existence of AM in the human nasal mucosa and to discuss whether AM might contribute to the pathogenesis of nasal congestion. We measured the total AM concentrations in the nasal discharge. The total AM concentration in the nasal discharge was significantly higher in the non-allergy group (72.1 ± 55.5 fmol/ml) than in the allergy group (37.1 ± 44.2 fmol/ml). By immunohistochemical examination, we identified AM-containing cells in the nasal mucosa from both subjects with and without nasal allergy, and also in nasal polyps. Moreover, those cells were positive for anti-tryptase antibody which recognizes mast cells. In nasal allergy, vasodilatation and increase in vascular permeability are characteristic features of the immediate phase response. Reduced AM levels in the nasal discharge may be associated with attenuation of both of these factors. On the other hand, immunohistochemical analysis demonstrated AM-immunoreactive cells in the chronic phase of rhinosinusitis. In the late and inflammatory phase, mast cells produce AM, which possibly acts as an inhibitor of inflammatory cell migration. In conclusion, AM may be actively secreted into the nasal discharge. AM in the nasal discharge may have protective and anti-inflammatory effects in the nasal mucosa.