Asthma, a family of airway disorders characterized by airway inflammation, has an increasing incidence worldwide. Platelet-activating factor (PAF) may play a role in the pathophysiology of asthma. Its proinflammatory actions are antagonized by PAF acetylhydrolase. A missense mutation (V279F) in the PAF acetylhydrolase gene results in the complete loss of activity, which occurs in 4% of the Japanese population. We asked if PAF acetylhydrolase deficiency correlates with the incidence and severity of asthma in Japan. We found that the prevalence of PAF acetylhydrolase deficiency is higher in Japanese asthmatics than healthy subjects and that the severity of this syndrome is highest in homozygous-deficient subjects. We conclude that the PAF acetylhydrolase gene is a modulating locus for the severity of asthma. J. Clin. Invest. 103:989-997

The 2008-2013 World Health Organization (WHO) action plan on noncommunicable diseases (NCDs) includes chronic respiratory diseases as one of its four priorities. Major chronic respiratory diseases (CRDs) include asthma and rhinitis, chronic obstructive pulmonary disease, occupational lung diseases, sleep-disordered breathing, pulmonary hypertension, bronchiectiasis and pulmonary interstitial diseases. A billion people suffer from chronic respiratory diseases, the majority being in developing countries. CRDs have major adverse effects on the life and disability of patients. Effective intervention plans can prevent and control CRDs, thus reducing morbidity and mortality. A prioritised research agenda should encapsulate all of these considerations in the frame of the global fight against NCDs. This requires both CRD-targeted interventions and transverse NCD programmes which include CRDs, with emphasis on health promotion and disease prevention.

Recent in vitro studies have suggested that interleukin-4 (IL-4) may be involved in the preferential migration of eosinophils into the airways in allergic asthma through its capacity to selectively increase vascular cell adhesion molecule-1 (VCAM-1) expression on vessels. To test this hypothesis, we studied the expression of VCAM-1, E-selectin, and intercellular adhesion molecule-1 (ICAM-1) on vascular endothelium in bronchial mucosal biopsies from 20 allergic asthmatics using an immunohistochemistry technique and related the observations to IL-4 levels in bronchoalveolar lavage (BAL) fluid simultaneously obtained and to eosinophil infiltration in the bronchial mucosa. IL-4 was detectable in BAL fluid from nine subjects (range, 15.1 to 110 pg/ml in 20-fold concentrated BAL fluid) (IL-4-positive asthmatics) but unmeasurable in the remaining 11 subjects (IL-4-negative asthmatics). The IL-4-positive asthmatics showed a significantly increased expression of VCAM-1 but not E-selectin and ICAM-1 on vessels as compared with both IL-4-negative asthmatics (P < 0.001) and diseased control subjects (P < 0.001). In asthmatics, VCAM-1 expression was positively correlated with BAL IL-4 levels (rs = 0.89; P < 0.0001). Moreover, there was a significant correlation between the endothelial expression of VCAM-1 and the number of eosinophils, but not neutrophils, in the bronchial submucosa (r2 = 0.76; P < 0.001). A significant correlation was also found between BAL IL-4 levels and the number of eosinophils. These results suggest that IL-4 is a VCAM-1-selective activator also in human airways and the VCAM-1-dependent pathways play a role in selective migration of eosinophils into the airways in allergic asthma, and support the hypothesis described above.

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