ABCF1 regulates dsDNA-induced immune responses in human airway epithelial cells

The airway epithelium represents a critical component of the human lung that helps orchestrate defences against respiratory tract viral infections, which are responsible for more than 2.5 million deaths/year globally. Innate immune activities of the airway epithelium rely Toll-like receptors (TLRs), nucleotide binding and leucine-rich-repeat pyrin domain containing (NLRP) receptors, and cytosolic nucleic acid sensors. ATP Binding Cassette (ABC) transporters are ubiquitous across all three domains of life – Archaea, Bacteria, and Eukarya – and expressed in the human airway epithelium. ABCF1, a unique ABC family member that lacks a transmembrane domain, has been defined as a cytosolic nucleic acid sensor that regulates CXCL10, interferon-b expression, and downstream type I interferon responses. We tested the hypothesis that ABCF1 functions as a dsDNA nucleic acid sensor in human airway epithelial cells important in regulating antiviral responses. Human airway epithelial cell line HBEC-6KT submerged monolayer cultures (n=24) were exposed to basal and VACV-70 viral stimulation conditions, with and without ABCF1 knock-down via siRNA. Basal conditions were as follows: media only (n=3), transfection agent only (n=3), transfection agent + control siRNA (n=3), and transfection agent + ABCF1 siRNA (n=3). Stimulation conditions were as follows: control siRNA + control VACV-70 (n=3), control siRNA + VACV-70 (n=3), ABCF1 siRNA + control VACV-70 (n=3), and ABCF1 siRNA + VACV-70 (n=3). After knock-down via 24 hour transfection with ABCF1 or control siRNA, cells were transfected with an immunostimulatroy ligand for 24 hours followed by gene expression outcome measurement via Affymetrix Clariom S Human microarray analysis.