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The findings point toward a mechanism by which galectin-3 may serve in the assembly of AGE-R components and in the efficient cell surface attachment and endocytosis by macrophages of a heterogenous pool of AGE moieties with diverse affinities, thus contributing to the elimination of these pathogenic substances.

Rationale: Respiratory syncytial virus (RSV) is the most frequent cause of significant lower respiratory illness in infants and young children, but its pathogenesis is not fully understood. The transcription factor Nrf 2 protects lungs from oxidative injury and inflammation via antioxidant response element (ARE)-mediated gene induction. Objectives: The current study was designed to determine the role of Nrf 2-mediated cytoprotective mechanisms in murine airway RSV disease. Methods: Nrf 2-deficient (Nrf 2 2/2 ) and wild-type (Nrf 2 1/1 ) mice were intranasally instilled with RSV or vehicle. In a separate study, Nrf 2 1/1 and Nrf 2 2/2 mice were treated orally with sulforaphane (an Nrf 2-ARE inducer) or phosphate-buffered saline before RSV infection. Measurements and Main Results: RSV-induced bronchopulmonary inflammation, epithelial injury, and mucus cell metaplasia as well as nasal epithelial injury were significantly greater in Nrf 2 2/2 mice than in Nrf 2 1/1 mice. Compared with Nrf 2 1/1 mice, significantly attenuated viral clearance and IFN-g, body weight loss, heightened protein/ lipid oxidation, and AP-1/NF-kB activity along with suppressed antioxidant induction was found in Nrf 2 2/2 mice in response to RSV. Sulforaphane pretreatment significantly limited lung RSV replication and virus-induced inflammation in Nrf 2 1/1 but not in Nrf 2 2/2 mice. Conclusions: The results of this study support an association of oxidant stress with RSV pathogenesis and a key role for the Nrf 2-ARE pathway in host defense against RSV.

In this report we demonstrate that reovirus serotype 1-infected cells contain an inhibitor of the interferoninduced, double-stranded RNA (dsRNA)-dependent protein kinase. We provide evidence that suggests that the virusencoded a3 protein is likely responsible for this kinase inhibitory activity. We could not detect activation of the dsRNAdependent protein kinase in extracts prepared from either interferon-treated or untreated reovirus serotype 1-infected

Double-stranded RNA (dsRNA) is a potent signal to the host immune system for the presence of an ongoing viral infection. The presence of dsRNA, intracellularly or extracellularly, leads to the induction of innate inflammatory cytokines in many cell types including epithelial cells. However, the cell surface receptor for recognition of extracellular dsRNA is not yet determined. Here, we report that extracellular dsRNA is recognized and internalized by scavenger receptor class-A (SR-A). Treatment of human epithelial cells with specific antagonists of SR-A or with an anti-SR-A antibody significantly inhibited dsRNA induction of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-8, and regulated on activation normal T-cell expressed and secreted (RANTES). Furthermore, intranasal dsRNA treatment of SR-A-deficient (SR-A(-/-)) mice showed a significant decrease in the expression of inflammatory cytokines and a corresponding decrease in the accumulation of polymorphonuclear leukocytes (PMNs) in lungs. These data provide direct evidence that SR-A is a novel cell surface receptor for dsRNA, and therefore, SR-A may play a role in antiviral immune responses.

Respiratory syncytial virus (RSV) is a common respiratory viral infection in children which is associatedwith immune dysregulation and subsequent induction and exacerbations of asthma. We recently reported that treatment of primary human epithelial cells (PHBE cells) with transforming growth factor ␤ (TGF-␤) enhanced RSV replication. Here, we report that the enhancement of RSV replication is mediated by induction of cell cycle arrest. These data were confirmed by using pharmacologic inhibitors of cell cycle progression, which significantly enhanced RSV replication. Our data also showed that RSV infection alone resulted in cell cycle arrest in A549 and PHBE cells. Interestingly, our data showed that RSV infection induced the expression of TGF-␤ in epithelial cells. Blocking of TGF-␤ with anti-TGF-␤ antibody or use of a specific TGF-␤ receptor signaling inhibitor resulted in rescue of the RSV-induced cell cycle arrest, suggesting an autocrine mechanism. Collectively, our data demonstrate that RSV regulates the cell cycle through TGF-␤ in order to enhance its replication. These findings identify a novel pathway for upregulation of virus replication and suggest a plausible mechanism for association of RSV with immune dysregulation and asthma.

During normal aging and in chronic diabetes the excessive accumulation of reactive glucose-protein or glucose-lipid adducts known as advanced glycosylation endproducts (AGEs) has been shown to induce tissue dysfunction, in part through interaction with AGE-specific receptors on monocyte/macrophages and other cells. Recognizing that circulating lymphocytes trafficking through tissues interact with tissue AGEs, we searched for the expression of AGE-binding sites on peripheral blood T lymphocytes. Resting rat and human T cells bound 125I-AGE-albumin with an affinity of 7.8 x 10(7) M-1, whereas, after stimulation with phytohemagglutinin (PHA) for 48 h, binding affinity increased to 5.8 x 10(8) M-1. Flow cytometric analysis of resting rat T cells using polyclonal antibodies raised against rat liver AGE-binding proteins (p60 and p90) revealed the constitutive expression of both immunoreactivities. The number of resting CD4+ and CD8+ T cells positive for anti-p60 antibody binding (34.2 and 58.5%, respectively) increased to 92 and 90% of cells after 48-h stimulation with PHA. Exposure of PHA-activated T lymphocytes to AGE-albumin enhanced expression of interferon gamma (IFN-gamma) mRNA 10-fold and induced greater elaboration of the mature protein than did exposure to unmodified protein or PHA treatment alone. These data indicate that T cells contain an inducible system of surface receptors for AGE-modified proteins, and that receptor occupancy is linked to lymphokine production. This T cell AGE-receptor system might serve to target lymphocytes to AGE-rich tissues and involve them in the regulation of tissue homeostasis either by assisting in macrophage-dependent clearance of AGE-proteins, or by exerting direct antiproliferative action on mesenchymal cells. Under conditions of excessive AGE-protein and AGE lipid accumulation (e.g., aging and diabetes), enhanced production of AGE-induced IFN-gamma may accelerate immune responses that contribute to tissue injury.

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