RESUMO
BACKGROUND: Congenital absence of the thymus can lead to profound immunodeficiency, suggesting that thymic function during fetal development is essential to normal lymphocyte development. How vital the thymus after birth is to human immune competence and regulation is not known. Routine thymectomy, especially at an early age, may influence immunity, and therefore the risk of infection, autoimmunity, or malignancy. METHODS: A retrospective review of cardiac surgery patients followed at Seattle Children's Hospital was performed. The primary outcome was rate of serious infections requiring hospitalization. Secondary analyses included age, type of infection, cardiac diagnosis, surgical procedure, and comorbidities. RESULTS: Patients fell into 2 groups: 60 with complete thymectomy and 35 with partial or no thymectomy. There was no statistical difference between groups in the overall prevalence of serious infections (16.7% vs 17.2%, P = 1.0). There was a nonsignificant trend toward reduced time between surgery and onset of first infection in patients in the total thymectomy group versus those without thymectomy (1.7 years vs 4.6 years, P = .07). Total thymectomy before 6 months of age also tended to increase infection rate, but the effect was not significant (0.09/year vs 0.02, P = .14). Gastroesophageal reflux in patients with total thymectomy increased the risk of infection (P = .013), suggesting a cumulative effect. CONCLUSIONS: Though infections occurred frequently in the childhood cardiac surgery population, total thymectomy was not associated with increased risk of serious infection. Comorbid conditions may be more important contributing factors increasing the risk of infection in this complex and vulnerable population.
RESUMO
Asthma is an inflammatory disorder of the airways that has been typified by its bronchospastic component. New attention has been directed to the long-term changes in asthmatic airways as indicated by the accelerated rate of lung function decline occurring in these patients despite therapy with inhaled corticosteroids. These structural changes in the airway wall, termed airway remodeling, are now thought to be a key component in the pathophysiology of asthma. Airway remodeling is characterized by thickening of the lamina reticularis with deposition of collagen and other extracellular matrix proteins leading to subepithelial fibrosis and increased airway goblet cells causing mucus hypersecretion. Of note, there is myofibroblast proliferation and increased airway smooth muscle mass caused by both hyperplasia and hypertrophy of smooth muscle cells. While an important role for cysteinyl leukotrienes (CysLTs) in the pathogenesis of airway inflammation and bronchoconstriction in asthma has been well-established, the specific role of CysLTs in airway remodeling is less clear. This aim of this review is to summarize the data from mouse models of asthma as well as limited human studies that demonstrate a key role for CysLTs in allergen-induced mucus hypersecretion, thickening of the lamina reticularis, and subepithelial fibrosis in the lungs. We will also focus on the interaction between CysLTs and cytokines/growth factors that mediate these changes in epithelial cells, smooth muscle cells, vasculature, and other structural components of the lungs in patients with asthma.
