Human airway epithelial cells produce IP-10 (CXCL10) in vitro and in vivo upon rhinovirus infection.

Human rhinovirus (HRV) infections trigger exacerbations of asthma and chronic obstructive pulmonary disease (COPD) and are associated with lymphocytic infiltration of the airways. We demonstrate that infection of primary cultures of human airway epithelial cells, or of the BEAS-2B human bronchial epithelial cell line, with human rhinovirus type 16 (HRV-16) induces expression of CXCL10 [IFN-gamma-inducible protein 10 (IP-10)], a ligand for the CXCR3 receptor found on activated type 1 T lymphocytes and natural killer cells. IP-10 mRNA reached maximal levels 24 h after HRV-16 infection then declined, whereas protein levels peaked 48 h after infection with no subsequent new synthesis. Cytosolic levels of AU-rich factor 1, a protein associated with mRNA destabilization, increased beginning 24 h after HRV-16 infection. Generation of IP-10 required virus capable of replication but was not dependent on prior induction of type 1 interferons. Transfection of synthetic double-stranded RNA into epithelial cells induced robust production of IP-10, whereas transfection of single-stranded RNA had no effect. Induction of IP-10 gene expression by HRV-16 depended upon activation of NF-kappaB, as well as other transcription factor recognition sequences further upstream in the IP-10 promoter. In vivo infection of human volunteers with HRV-16 strikingly increased IP-10 protein in nasal lavages during symptomatic colds. Levels of IP-10 correlated with symptom severity, viral titer, and numbers of lymphocytes in airway secretions. Thus IP-10 may play a role in the pathogenesis of HRV-induced colds and in HRV-induced exacerbations of COPD and asthma.

Role of nasal nitric oxide in the resolution of experimental rhinovirus infection.

BACKGROUND: Human rhinovirus (HRV) infections are associated with exacerbations of asthma, chronic obstructive pulmonary disease, and sinusitis. Nitric oxide (NO) might play an important role in host defense through its potent antiviral properties. Previous studies have shown that HRV infection in human subjects increased nasal epithelial expression of type 2 nitric oxide synthase (NOS2), an isoform of the enzyme that produces NO. OBJECTIVE: We sought to investigate whether increases in exhaled NO (eNO) would accompany the increased NOS2 expression and would be associated with clearance of the virus. METHODS: Six human subjects were infected with HRV-16 intranasally. eNO from nasal and lower airways was measured by means of direct measurement at multiple controlled flow rates. eNO was monitored at baseline (day 1) and on days 2 to 5, 8, 14, and 42 after infection. Nasal lavages were performed on days 1 to 5 and 8, and nasal scrapings were performed on days 1 to 4. NOS2 mRNA expression in nasal cells was measured by using quantitative real-time RT-PCR. Viral shedding in nasal lavage fluid was monitored by using real-time RT-PCR and bioassay. RESULTS: Peak HRV titers and symptom scores were correlated on day 3, and HRV persisted until day 5 (n=4) or day 8 (n=2). Infection was associated with transient but significant increases in lymphocytes and monocytes in nasal lavage fluid. Significant increases in both nasal and lower airway eNO concentrations accompanied HRV infection and were positively correlated. Increased nasal eNO concentrations on day 3 were associated with increased expression of NOS2 mRNA in nasal scrapings. Symptom scores on day 4 were inversely correlated with the increases in nasal eNO concentration. CONCLUSIONS: We conclude that increased production of NO occurs as part of the host response to HRV infection and speculate that NO plays a beneficial role in viral clearance.

Human rhinovirus infection induces airway epithelial cell production of human beta-defensin 2 both in vitro and in vivo.

We hypothesized that airway epithelial cells, the primary site of human rhinovirus (HRV) infection, provide a link between the innate and specific immune response to HRV via production of human beta-defensin (HBD)-2, a potent in vitro attractant and activator of immature dendritic cells. Infection of primary cultures of human epithelial cells with several HRV serotypes induced expression of HBD-2 mRNA and protein, indicating that HBD-2 production was independent of viral receptor usage or mechanisms of viral RNA internalization. Induction of HBD-2 was dependent upon viral replication and could be mimicked by transfection of cells with synthetic dsRNA, but was not dependent upon epithelial production of IL-1. Studies with stable epithelial cell lines expressing HBD-2 promoter constructs, as well as inhibitor studies in primary cells, both demonstrated that induction of HBD-2 involves activation of the transcription factor, NF-kappaB. Other transcription factors must also be activated by HRV infection, however, as expression of HBD-3 mRNA was also induced and there is no putative NF-kappaB recognition sequence in the promoter of this gene. HBD-2 showed no direct antiviral activity against HRV. In vivo infection of normal human subjects with HRV-16 induced expression of mRNA for HBD-2 in nasal epithelial scrapings. Increases in mRNA correlated with viral titer and with increased levels of HBD-2 protein in nasal lavages. This represents the first demonstration that HRV infection induces epithelial expression of HBD-2 both in vitro and in vivo, and supports the concept that HBD-2 may play a role in host defense to HRV infection.