Expression of respiratory syncytial virus-induced chemokine gene networks in lower airway epithelial cells revealed by cDNA microarrays

The Paramyxovirus respiratory syncytial virus (RSV) is the primary etiologi c agent of serious epidemic lower respiratory tract disease in infants, imm unosuppressed patients, and the elderly. Lower tract infection with RSV is characterized by a pronounced peribronchial mononuclear infiltrate, with eo sinophilic and basophilic degranulation. Because RSV replication is restric ted to airway epithelial cells, where RSV replication induces potent expres sion of chemokines, the epithelium is postulated to be a primary initiator of pulmonary inflammation in RSV infection. The spectrum of RSV-induced che mokines expressed by alveolar epithelial cells has not been fully investiga ted. In this report, we profile the kinetics and patterns of chemokine expr ession in RSV-infected lower airway epithelial cells (A549 and SAE). In A54 9 cells, membrane-based cDNA macroarrays and high-density oligonucleotide p robe-based microarrays identified inducible expression of CC (I-309, Exodus -1, TARC, RANTES, MCP-1, MDC, and MIP-1 alpha and -1 beta), CXC (GRO-alpha, -beta, and -gamma, ENA-78, interleukin-8 [IL-8], and I-TAC), and CX3C (Fra ctalkine) chemokines. Chemokines not previously known to be expressed by RS V-infected cells were independently confirmed by multiprobe RNase protectio n assay, Northern blotting, and reverse transcription-PCR. High-density mic roarrays performed on SAE cells confirmed a similar pattern of RSV-inducibl e expression of CC chemokines (Exodus-1, RANTES, and MIP-1 alpha and -1 bet a), CXC chemokines (I-TAC, GRO-alpha, -beta, and -gamma, and IL-8), and Fra ctalkine. In contrast, TARO, MCP-1, and MDC were not induced, suggesting th e existence of distinct genetic responses for different types of airway-der ived epithelial cells. Hierarchical clustering by agglomerative nesting and principal-component analyses were performed on A549-expressed chemokines; these analyses indicated that RSV-inducible chemokines are ordered into thr ee related expression groups. These data profile the temporal changes in ex pression by RSV-infected lower airway epithelial cells of chemokines, chemo tactic proteins which may be responsible for the complex cellular infiltrat e in virus-induced respiratory inflammation.