Intranasal heparin reduces eosinophil recruitment after nasal allergen challenge in patients with allergic rhinitis.

BACKGROUND: Recently, several studies have shown that heparin possesses various anti-inflammatory and antiallergic properties. It has been proposed that heparin might play an important role in limiting the inflammatory events associated with asthma and allergic rhinitis by neutralizing inflammatory mediators, such as eosinophil cationic protein and major basic protein, and by limiting eosinophil recruitment. OBJECTIVE: To test the hypothesis that heparin can limit the extent and magnitude of eosinophilic inflammation, we examined the effect of inhaled intranasal heparin on nasal response to allergen challenge in 10 patients with allergic rhinitis. METHODS: The capacity of heparin to reduce nasal response was studied by evaluating symptom score, eosinophil cationic protein concentration, and eosinophil counts in nasal lavage fluids 10, 60, and 360 minutes after allergen challenge. RESULTS: Pretreatment with intranasal heparin produced a significant reduction in symptom score 10 minutes after allergen challenge and reduced the eosinophil influx at each time point after antigen challenge, statistical significance being reached 60 and 360 minutes after allergen challenge. Similarly, the amount of eosinophil cationic protein in the nasal wash was reduced at each time point; this reached statistical significance 360 minutes after allergic challenge. CONCLUSION: Heparin was shown to provide protection with respect to nasal allergen challenge. The mechanism by which heparin produces its protective activity seems to be related to the neutralization of eosinophil cationic protein as well as to the reduction of eosinophil recruitment.

Time course of changes in adenosine 5'-monophosphate airway responsiveness with inhaled heparin in allergic asthma.

BACKGROUND: Recent studies have shown that inhaled heparin exerts a protective effect against various bronchoconstrictor stimuli in asthma, possible through an inhibition of mast cell activation. OBJECTIVE: Because adenosine 5'-monophosphate (AMP) elicits bronchoconstriction by augmenting mast cell mediator release, we have investigated the effect of inhaled heparin (15,000 units USP/ml, 4 ml) on the bronchoconstrictor response to this agonist and to methacholine in a randomized, double-blind, placebo-controlled study of 10 subjects with asthma. We also carried out a separate randomized, double-blind study in seven additional volunteers with asthma to examine in more detail the time-course of change in bronchial reactivity to inhaled AMP after treatment with nebulized heparin. RESULTS: Inhaled heparin significantly increased the provocative concentration of AMP causing a 20% decrease in forced expiratory volume in 1 second (PC20 FEV1-AMP) from the postplacebo treatment value of 22.3 mg/ml (range, 5.7 to 68.9 mg/ml) to 48.1 mg/ml (range, 5.1-196.8 mg/ml) (p < 0.01). When compared with placebo, inhaled heparin failed to alter the airway responsiveness to methacholine; the mean (range) PC20 methacholine values were 1.00 mg/ml (0.44 to 4.76 mg/ml) and 1.08 mg/ml (0.46 to 5.08 mg/ml), respectively. After placebo administration, the PC20 AMP values at 15, 60, and 180 minutes did not differ significantly from each other; their geometric mean (range) values were 26.1 mg/ml (5.9 to 85.8 mg/ml), 26.6 mg/ml (6.3 to 87.8 mg/ml), and 24.9 mg/ml (5.2 to 80.2 mg/ml), respectively. When compared with placebo, the PC20 values for AMP after administration of inhaled heparin were significantly increased up to 57.3 mg/ml (14.7 to 176.0 mg/ml) and to 52.7 mg/ml (13.9 to 90.8 mg/ml) at 15 minutes and 60 minutes, respectively. At 180 minutes, inhaled heparin failed to affect AMP airway responsiveness; the PC20 AMP was not significantly different from that of placebo, with a value of 30.6 mg/ml (4.8 to 93.3 mg/ml). CONCLUSION: Heparin administered by inhalation is effective in attenuating the airway response to AMP but not to methacholine. The time course of change in bronchial reactivity to AMP has a peak effect at 15 minutes and lasts up to 60 minutes. It is possible that the mechanism(s) underlying the protective effects of inhaled heparin in asthma may be related to an inhibitory modulation of mast cell activation.

Neutral endopeptidase inhibition with inhaled phosphoramidon: no effect on bronchial responsiveness to adenosine 5'-monophosphate (AMP) in asthma.

Part of the contractile response of adenosine in the asthmatic airways may be due to the activation of peptidergic pathways with subsequent local release of spasmogenic neuropeptides. At present, little is known about the potential role of lung peptidases in modulating adenosine-induced airway dysfunction in humans in vivo. We have, therefore, investigated the change in bronchial reactivity to adenosine 5'-monophosphate (AMP), after treatment with inhaled phosphoramidon, a potent neutral endopeptidase (NEP) inhibitor, in a double-blind, placebo-controlled, randomized study of 12 asthmatic subjects. Subjects attended on six separate occasions, during which concentration response studies with inhaled AMP and methacholine were carried out, initially in the absence of treatment and then after nebulized phosphoramidon sodium salt (10[-5] M) or matched placebo 5 min prior to a bronchoprovocation test with AMP or methacholine. Agonist responsiveness was expressed as the provocative concentration of AMP or methacholine producing a 20% fall in FEV1 from baseline (PC[20,AMP] or PC[20,meth], respectively). When compared to placebo, phosphoramidon failed to potentiate the airway response to AMP. The geometric mean (range) PC20 AMP value of 23.4 (4.4-190.6) mg x mL(-1) after placebo was not significantly different from that of 20.7 (45-100.9) mg x mL(-1) obtained after phosphoramidon. The lack of change in bronchial reactivity to adenosine 5'-monophosphate after phosphoramidon indicates that endogenous airway neutral endopeptidase may not be of physiological importance in modulating the contractile response of adenosine in the airways. Thus, the present data do not support the view that activation of peptidergic pathways with subsequent local release of spasmogenic neuropeptides is important in the airway response to adenosine