Human rhinovirus-induced ISG15 selectively modulates epithelial antiviral immunity.

Human rhinovirus (HRV) infections trigger exacerbations of lower airway diseases. HRV infects human airway epithelial cells and induces proinflammatory and antiviral molecules that regulate the response to HRV infection. Interferon (IFN)-stimulated gene of 15 kDa (ISG15) has been shown to regulate other viruses. We now show that HRV-16 infection induces both intracellular epithelial ISG15 expression and ISG15 secretion in vitro. Moreover, ISG15 protein levels increased in nasal secretions of subjects with symptomatic HRV infections. HRV-16-induced ISG15 expression is transcriptionally regulated via an IFN regulatory factor pathway. ISG15 does not directly alter HRV replication but does modulate immune signaling via the viral sensor protein RIG-I to impact production of CXCL10, which has been linked to innate immunity to viruses. Extracellular ISG15 also alters CXCL10 production. We conclude that ISG15 has a complex role in host defense against HRV infection, and that additional studies are needed to clarify the role of this molecule.

Cigarette smoke modulates rhinovirus-induced airway epithelial cell chemokine production.

Human rhinovirus (HRV) infections induce epithelial cell production of chemokines that may contribute to the pathogenesis of exacerbations of chronic obstructive pulmonary disease (COPD) and asthma. Cigarette smoking is the predominant risk factor for the development of COPD and also aggravates asthma symptoms. We examined whether cigarette smoke extract (CSE) modulates viral inflammation by altering the profile of HRV-induced epithelial chemokine production. Purified HRV-16, and CSE were used to examine the effects on CXC chemokine ligand (CXCL)8 and CXCL10 production from both primary human bronchial epithelial cells and the BEAS-2B epithelial cell line. Both CSE and HRV-16 induced CXCL8 production and, when used in combination, induced at least an additive production of CXCL8 compared with either stimulus alone. In contrast, CSE did not induce CXCL10 and markedly inhibited HRV-16-induced CXCL10 production. Inhibition of HRV-16-induced CXCL10 by CSE was mediated, at least in part, via transcriptional regulation. The increased CXCL8 production seen with the combination of CSE and HRV-16 was not due to transcriptional regulation but was associated with CXCL8 mRNA stabilisation. Thus, CSE differentially modulates HRV-16-induced chemokine production from human airway epithelial cells in a manner that might be expected to alter inflammatory cell profiles.