Synergy Of IL-27and TNF-A In Regulating CXCL10Expression In Lung Fibroblasts: Implications In Airway Inflammation

IL-27is involved in inflammatory reactions. CXCL10is an importantchemokine contributing to airway inflammatory diseases. In this study, weinvestigated whether IL-27modulated the synthesis of CXCL10in primaryhuman pulmonary fibroblasts (HPF). HPF were activated by IL-27alone, orin combination with other cytokines. CXCL10synthesis was measured byreal-time PCR and ELISA. mRNA stability was assessed by actinomycin Dchase and real-time PCR. The underlying signaling pathways were studiedby Western blot and intracellular staining using flow cytometry. Our resultsdemonstrated that IL-27induced and synergized with TNF-α to upregulateCXCL10mRNA and protein levels in a steroid-insensitive manner. Thissynergistic CXCL10production was dependent on transcriptional regulationof CXCL10gene promoter activity and the enhanced stability of CXCL10mRNA by IL-27and TNF-α, and this synergism was regulated by theactivation of p38MAPK and PI3K-Akt dominantly and in a little part viaNF-κB. Interestingly, IL-27promoted basal and enhanced TNF-α-inducedphosphorylation of p38MAPK and Akt, but not IκBα. Besides, the enhancedCXCL10mRNA stability occurred via a p38MAPK-dependent pathway. Finally, clinical analysis showed that IL-27was detected in BAL of patientswith asthma, COPD, and PTB, and the increased IL-27levels was correlatedwith the increased CXCL10levels in patients with COPD and PTB. Ourfindings suggest that IL-27has the potential to amplify airway inflammationvia the induction of CXCL10from HLF in combination with TNF-α.