Iminosugar-Based Inhibitors of Glucosylceramide Synthase Increase Brain Glycosphingolipids and Survival in a Mouse Model of Sandhoff Disease

The neuropathic glycosphingolipidoses are a subgroup of lysosomal storage disorders for which there are no effective therapies. A potential approach is substrate reduction therapy using inhibitors of glucosylceramide synthase (GCS) to decrease the synthesis of glucosylceramide and related glycosphingolipids that accumulate in the lysosomes. Genz-529468, a blood-brain barrier-permeant iminosugar-based GCS inhibitor, was used to evaluate this concept in a mouse model of Sandhoff disease, which accumulates the glycosphingolipid GM2 in the visceral organs and CNS. As expected, oral administration of the drug inhibited hepatic GM2 accumulation. Paradoxically, in the brain, treatment resulted in a slight increase in GM2 levels and a 20-fold increase in glucosylceramide levels. The increase in brain glucosylceramide levels might be due to concurrent inhibition of the non-lysosomal glucosylceramidase, Gba2. Similar results were observed with NB-DNJ, another iminosugar-based GCS inhibitor. Despite these unanticipated increases in glycosphingolipids in the CNS, treatment nevertheless delayed the loss of motor function and coordination and extended the lifespan of the Sandhoff mice. These results suggest that the CNS benefits observed in the Sandhoff mice might not necessarily be due to substrate reduction therapy but rather to off-target effects

Expression of programmed death-1 ligand (PD-L) 1, PD-L2, B7-H3, and inducible costimulator ligand on human respiratory tract epithelial cells and regulation by respiratory syncytial virus and type 1 and 2 cytokines

BACKGROUND: Respiratory syncytial virus (RSV) is associated with wheezing illness, and infections can occur repeatedly throughout life. We hypothesized that RSV infection of respiratory tract epithelial cells up-regulates B7 molecules that regulate memory immune responses and that type 1 and 2 cytokines differentially modulate this induction. METHODS: We used flow-cytometric analysis to investigate programmed death-1 ligand (PD-L) 1, PD-L2, B7-H3, and inducible costimulatory ligand (ICOS-L) expression on tracheal (NCI-H292), bronchial (BEAS-2B), and alveolar (A549) epithelial cells; regulation of this expression by RSV, interferon (IFN)- gamma , and interleukin (IL)-4; and the effects of IFN-gamma and IL-4 on RSV-induced expression of these molecules. RESULTS: B7-H3 was strongly expressed, PD-L1 and ICOS-L were moderately expressed, and PD-L2 was weakly expressed on unstimulated tracheal, bronchial, and alveolar epithelial cells. RSV infection up-regulated PD-L1, PD-L2, and B7-H3 expression on all cells and ICOS-L expression on bronchial and alveolar epithelial cells. IL-4 treatment alone had no effect, whereas IFN-gamma treatment alone increased PD-L1 and PD-L2 expression on all cells and decreased B7-H3 expression on bronchial and alveolar epithelial cells. On RSV-infected alevolar epithelial cells, IFN-gamma treatment increased PD-L1 and PD-L2 expression and decreased B7-H3 and ICOS-L expression, and IL-4 treatment increased PD-L2 and B7-H3 expression and decreased ICOS-L expression. CONCLUSIONS: Respiratory tract epithelial cells express a wide range of B7 molecules. RSV infection increases their expression, and this expression is differentially regulated by IFN-gamma and IL-4. These processes may be involved in decreasing T cell antiviral immune responses to RSV and in RSV-associated wheezing

Reducing agents inhibit rhinovirus-induced up-regulation of the rhinovirus receptor intercellular adhesion molecule-1 (ICAM-1) in respiratory epithelial cells

Rhinoviruses are the major cause of common colds and of asthma exacerbations. Intercellular adhesion molecule-1 (ICAM-1) has a central role in airway inflammation and is the receptor for 90% of rhinoviruses. Rhinovirus infection of airway epithelium induces ICAM-1. Because redox state is directly implicated in inflammatory responses via molecular signaling mechanisms, here we studied the effects of reducing agents on rhinovirus-induced ICAM-1 expression, mRNA up-regulation, promoter activation, and nuclear factor activation. To investigate the effects of rhinovirus infection on the intracellular redox balance, we also studied whether rhinovirus infection triggers the production of reactive oxygen species. We found that reduced (GSH) but not oxidized (GSSG) glutathione (1-100 microM) inhibited in a dose-dependent manner rhinovirus-induced ICAM-1 up-regulation and mRNA induction in primary bronchial and A549 respiratory epithelial cells. GSH but not GSSG also inhibited rhinovirus-induced ICAM-1 promoter activation and rhinovirus-induced NF-kB activation. In parallel, we found that rhinovirus infection induced a rapid increase of intracellular superoxide anion that was maximal at the time of NF-kB activation. This oxidant generation was completely inhibited by GSH. We conclude that redox-mediated intracellular pathways represent an important target for the therapeutic control of rhinovirus-induced disease

Infections and airway inflammation in chronic obstructive pulmonary disease severe exacerbations

RATIONALE: Severe exacerbations of chronic obstructive pulmonary disease (COPD) are major causes of health care costs mostly related to hospitalization. The role of infections in COPD exacerbations is controversial. OBJECTIVES: We investigated whether COPD exacerbations requiring hospitalization are associated with viral and/or bacterial infection and evaluated relationships among infection, exacerbation severity, assessed by reduction of FEV1, and specific patterns of airway inflammation. METHODS: We examined 64 patients with COPD when hospitalized for exacerbations, and when in stable convalescence. We measured lung function, blood gases, and exhaled nitric oxide, and examined sputum for inflammation and for viral and bacterial infection. RESULTS: Exacerbations were associated with impaired lung function (p < 0.01) and increased sputum neutrophilia (p < 0.001). Viral and/or bacterial infection was detected in 78% of exacerbations: viruses in 48.4% (6.2% when stable, p < 0.001) and bacteria in 54.7% (37.5% when stable, p = 0.08). Patients with infectious exacerbations (29.7% bacterial, 23.4% viral, 25% viral/bacterial coinfection) had longer hospitalizations (p < 0.02) and greater impairment of several measures of lung function (all p < 0.05) than those with noninfectious exacerbations. Patients with exacerbations with coinfection had more marked lung function impairment (p < 0.02) and longer hospitalizations (p = 0.001). Sputum neutrophils were increased in all exacerbations (p < 0.001) and were related to their severity (p < 0.001), independently of the association with viral or bacterial infections; sputum eosinophils were increased during (p < 0.001) virus-associated exacerbations. CONCLUSIONS: Respiratory infections are associated with the majority of COPD exacerbations and their severity, especially those with viral/bacterial coinfection. Airway neutrophilia is related to exacerbation severity regardless of viral and/or bacterial infections. Eosinophilia is a good predictor of viral exacerbations