Pulmonary function and airway hyperresponsiveness in adults with sickle cell disease.
ABSTRACT Pulmonary involvement is a major cause of morbidity and mortality in patients with sickle cell disease (SCD). Although a high prevalence of airway hyperresponsiveness (AHR) has been reported, there are no studies demonstrating the relationship between AHR and acute chest syndrome (ACS) in adults with SCD. We investigated AHR prevalence, lung function abnormalities, and the relationships of these variables with ACS in SCD patients.
Thirty-one adult patients without asthmatic symptoms were compared with 31 matched controls. Expiratory flow rates, lung volumes, carbon monoxide diffusion capacity (DLCO), and methacholine provocation test (MPT) results were assessed.
Forced vital capacity (FVC), forced expiratory volume in one second, forced expiratory flow rate at 25% to 75% of FVC (FEF(25%-75%)), peak expiratory flow rate, total lung capacity, and DLCO values were significantly lower in the patient group than in the controls. No significant difference in pulmonary function test results was found between patients with and without a history of ACS. Fifteen patients with SCD (48%) and only 5 controls (16%) had AHR (p = 0.007). A significant correlation was found between the number of ACS episodes and MPT positivity (r = 0.379, p = 0.035). The FEF(25%-75%) values were significantly lower in patients with positive MPT results than in patients with negative MPT results (p = 0.027).
The prevalence of AHR was high in adult patients with SCD. A significant correlation was found between AHR and recurrent ACS episodes. Anti-inflammatory controller agents can be used routinely to decrease pulmonary morbidity associated with SCD, even in the absence of asthmatic symptoms.
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ABSTRACT: In recent years, evidence has accumulated indicating that the enzyme arginase, which converts L-arginine into L-ornithine and urea, plays a key role in the pathogenesis of pulmonary disorders such as asthma through dysregulation of L-arginine metabolism and modulation of nitric oxide (NO) homeostasis. Allergic asthma is characterized by airway hyperresponsiveness, inflammation, and remodeling. Through substrate competition, arginase decreases bioavailability of L-arginine for nitric oxide synthase (NOS), thereby limiting NO production with subsequent effects on airway tone and inflammation. By decreasing L-arginine bioavailability, arginase may also contribute to the uncoupling of NOS and the formation of the proinflammatory oxidant peroxynitrite in the airways. Finally, arginase may play a role in the development of chronic airway remodeling through formation of L-ornithine with downstream production of polyamines and L-proline, which are involved in processes of cellular proliferation and collagen deposition. Further research on modulation of arginase activity and L-arginine bioavailability may reveal promising novel therapeutic strategies for asthma.Journal of Allergy 01/2011; 2011:736319.