Human metapneumovirus establishes persistent infection in the lungs of mice and is reactivated by glucocorticoid treatment.

Human metapneumovirus (HMPV) has been identified as a worldwide agent of serious upper and lower respiratory tract infections in infants and young children. HMPV is second only to respiratory syncytial virus (RSV) as a leading cause of bronchiolitis, and, like RSV, consists of two major genotypes that cocirculate and vary among communities year to year. Children who have experienced acute HMPV infection may develop sequelae of wheezing and asthma; however, the features contributing to this pathology remain unknown. A possible mechanism for postbronchiolitis disease is that HMPV might persist in the lung providing a stimulus that could contribute to wheezing and asthma. Using immunohistochemistry to identify HMPV-infected cells in the lungs of mice, we show that HMPV mediates biphasic replication in respiratory epithelial cells then infection migrates to neuronal processes that innervate the lungs where the virus persists with no detectable infection in epithelial cells. After glucocorticoid treatment, the virus is reactivated from neural fibers and reinfects epithelial cells. The findings show that HMPV persists in neural fibers and suggest a mechanism for disease chronicity that has important implications for HMPV disease intervention strategies.

Drug analog inhibition of indoleamine 2,3-dioxygenase (IDO) activity modifies pattern recognition receptor expression and proinflammatory cytokine responses early during influenza virus infection.

Influenza virus is recognized by PRRs, which are critical in the early response to virus infection and induction of proinflammatory cytokines. IDO is increased in the lung of mice immediately following influenza infection, and the presence of IDO has been shown to mediate immune suppression through depletion of trp and reduction in IL-6 production. To determine the role of IDO activity in the early immune response to influenza infection, IDO activity was inhibited using the synthetic analog, 1MT. The results show that IDO inhibition enhanced proinflammatory cytokine gene and protein expression at 24 and 48 h postinfection, respectively, compared with control-treated mice and affected PRR expression. The enhanced proinflammatory response in the presence of 1MT was attributed to macrophages in the airways, as Raw264.7 and primary AMs showed enhanced production of IFN-ß, IL-1ß, IL-6, and TNF-α in the presence of 1MT. These findings provide important knowledge for the role of IDO during initial host response to influenza infection.

Evidence of vascular endothelial dysfunction in young patients with cystic fibrosis.

BACKGROUND: Cystic fibrosis (CF) is a genetic disorder that affects not only pulmonary function but also multiple organ systems. The fl ow-mediated dilation (FMD) test is a noninvasive assessment of endothelial function and nitric oxide bioavailability. Thus, the purpose of this study was to determine (1) whether endothelial dysfunction is present in young patients with CF and (2) whether endothelial function is associated with pulmonary function and exercise capacity. METHODS: Fifteen patients with CF and 15 demographically matched control subjects participated in this study. Spirometry, brachial-artery FMD, and a maximal exercise capacity test on a cycle ergometer were performed on all subjects to determine pulmonary function, endothelial function, and exercise capacity, respectively. RESULTS: No differences ( P . .05) in age, height, or BMI were observed between patients with CF and control subjects. FEV 1 (% predicted), FEV 1 /FVC, and forced expiratory fl ow between 25% and 75% of vital capacity were lower in patients with CF. Volume of oxygen consumption peak (absolute and relative) was similar between groups; however, volume of oxygen consumption (% predicted and mL/kg fat-free mass/min) and peak workload were significantly ( P , .05) lower in patients with CF. FMD (4.9% 2.6% vs 7.5% 3.1%; P 5 .018) was lower in patients compared with control subjects, respectively. Relationships between FMD and both pulmonary function and exercise capacity were identified. CONCLUSIONS: For the fi rst time to our knowledge, these data provide evidence of vascular endothelial dysfunction in a fairly healthy cohort of young patients with CF. In addition, our data demonstrate the complex relationships between endothelial function and both pulmonary function and exercise capacity in young patients with CF.