Aspirin induced asthma (AIA) with nasal polyps has the highest basal LTE4 excretion: a study vs AIA without polyps, mild topic asthma, and normal controls.

UNLABELLED

Cysteinil Leukotrienes (LTs) are products of the arachidonic acid cascade which are synthetised by 5-lipoxigenase in inflammatory cells, particularly in eosinophils. Urinary leukotriene E4 concentration (LTE4), that reflects the whole body production of cysteinil-leukotrienes, is particularly increased in patients with aspirin-intolerant asthma (AIA). Aim of the present study was to assess basal urinary LTE4 levels from AIA patients with nasal polyps to those from AIA patients with only rhinitis (without polyps), and those from mild atopic asthmatics and normal controls.

SUBJECTS & METHODS: 34 normal subjects (N; 19 - 57y, FEV1 = 102.1% pred. +/- 8.2 sd; negative MCh challenge; negative prick test); 39 mild-persistent atopic asthmatics (A; 18-66y, FEV1 = 92.1 %pred. +/- 14.6 sd; PD20 FEV1 = 380.7mcg +/- 481.2 sd); 24 subjects with AIA with rhinitis (AIA/R; 18 - 56y, FEV1 = 71.6%pred +/- 15.5 sd; reversibility = 15.1% bsln +/- 2.1 sd after salbutamol 200mg), and 10 subjects with AIA and nasal polyposis (AIA/NP; 22-49 y; FEV1 = 70.6%pred. +/- 7.1 sd; reversibility = 13.2% bsln +/- 1.6 sd after salbutamol 200 microg) were studied. After their informed consent, urine were collected in the morning for the LTE4 quantitative immunoenzimatic assay (pg/mg creatinine; Cayman Chemical, Ann Arbour, Mi, USA).

STATISTICS

Wilcoxon signed rank test was used, and p<0.05 accepted as the lowest level of statistical significance.

RESULTS

AIA/NP subjects had the highest levels of urinary LTE4 (432.3 pg/mg +/- 88.1 sd) compared to AIA/R (330.7 pg/mg +/- 72.3s, p < 0.01), to A (129.1 pg/mg +/- 74.8sd, p < 0.001), and to N controls (66.5 pg/mg +/- 20.6 sd, p < 0.001). Moreover, urinary LTE4 levels measured in AIA/R subjects proved significantly higher than those measured in A (p < 0.001) and in N controls (p<0.001), while LTE4 levels in A proved significantly higher than those in N controls (p<0.001). Furthermore, basal LTE4 levels seem inversely related to those of basal FEV1 (102.1 % pred. +/- 8.2sd in N, 92.1 % pred +/- 14.6 sd in A, 71.6 % pred. +/- 15.5 sd in AIA/R, 70.6 % pred +/- 7.1 sd in AIA/P, respectively). Respiratory function in the two sub-groups of AIA patients proved reduced than in atopic asthmatics (p<0.001) and in normal controls (p < 0.001), even though the difference between these two subgroups of subjects did not reach the statistical significance.

CONCLUSIONS

Cys-LTs confirm their relevant pathogenetic role in AIA, but also in early stages of atopic asthma. Urinary LTE4 exexcretion proves directly proportional to the extent of nasal structural changes occurring in ASA-intolerant asthmatics, being subjects with nasal polyps those with the highest LTE4 values, immediately followed by those with hypertrophic rhinitis. Routinary measurements of urinary LTE4 should be regarded as a sensitive indicator in monitoring the clinical evolution of nasal involvement in AIA.