The Journal of allergy and clinical immunology
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J. Allergy Clin. Immunol. · Nov 2008
Comparative StudyChitotriosidase is the primary active chitinase in the human lung and is modulated by genotype and smoking habit.
Chitinolytic enzymes play important roles in the pathophysiology of allergic airway responses in mouse models of asthma. Acidic mammalian chitinase (AMCase) and chitotriosidase (CHIT1) have chitinolytic activity, but relatively little is known about their expression in human asthma. ⋯ Chitinase activity in the lung is the result of CHIT1 activity. Although AMCase protein is detectable in the lung, our data indicate that it is inactive. Chitinase activity is not increased in subjects with asthma and in fact tends to be decreased. The high levels of chitinase activity in habitual smokers result from upregulation of CHIT1 gene expression, especially in macrophages.
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J. Allergy Clin. Immunol. · Nov 2008
Protective role of the lung collectins surfactant protein A and surfactant protein D in airway inflammation.
The acute inflammatory airway response is characterized by a time-dependent onset followed by active resolution. Emerging evidence suggests that epithelial cells of the proximal and distal air spaces release host defense mediators that can facilitate both the initiation and the resolution part of inflammatory airway changes. These molecules, also known as the hydrophilic surfactant proteins (surfactant protein [SP]-A and SP-D) belong to the class of collagenous lectins (collectins). ⋯ Investigations on gene-deficient and conditional overexpresser mice indicated that lung collectins also directly modulate innate immune cell function and T-cell-dependent inflammatory events. Thus, these molecules have a unique, dual-function capacity to induce pathogen elimination and control proinflammatory mechanisms, suggesting a potential suitability for therapeutic prevention and treatment of chronic airway inflammation. This article reviews evidence supporting that the lung collectins play an immune-protective role and are essential for maintenance of the immunologic homeostasis in the lung.
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J. Allergy Clin. Immunol. · Oct 2008
Multicenter StudyA community-based study of tobacco smoke exposure among inner-city children with asthma in Chicago.
Little is known about the level of tobacco exposure and the factors that influence exposure in children with persistent asthma. ⋯ Tobacco smoke exposure was high in this urban sample of asthmatic children. Caregiver smoking was strongly associated with child exposure and also was associated with lower socioeconomic status, non-Hispanic ethnicity, and depression symptoms.
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Asthma exacerbations are common, and the major morbidity, mortality, and health care costs associated with asthma are related to exacerbations. The majority are related to viral infection, and although progress has been made in identifying the mechanisms of virus-induced asthma exacerbations, there is still much to be learned. ⋯ Exacerbations are characterized by airway inflammation, which can differ in type depending on whether it is primarily infective or allergic in origin. An increased understanding of the inflammatory pathways might lead to identification of targets for the development of novel prevention or treatment strategies.