LIGHT in Combination with IL-13 or IL-17 Drives Inflammatory Phenotypes in Human Pulmonary Fibroblasts

Fibroblasts are primary structural cells involved in tissue remodelling, but recent transcriptomic data have highlighted the ability of fibroblasts to display molecules that contribute to inflammation. Which factors might drive such inflammatory phenotypes are unclear. LIGHT (TNFSF14) is a cytokine that we previously showed was involved in inflammation of the lungs and may be central to lung diseases exhibiting fibrosis and inflammation, including asthma and interstitial lung disease. With RNA-seq, we investigated the activity of LIGHT in human pulmonary fibroblasts compared to IL-13 and IL-17, two other cytokines linked to lung disease. While all three cytokines individually induced both unique and overlapping gene transcripts, when fibroblasts were stimulated with LIGHT and IL-13 they upregulated more inflammatory transcripts including CCL2, CCL26, CXCL2, CXCL3, CXCL5, CXCL6, IL32, CSF2, VCAM1, ICAM1, IL18R1, IL1RL1, TNFRSF12A, TNFRSF4, TNFRSF8, ITGA2, ITGA4, and ITGAV; and when stimulated with LIGHT and IL-17, inflammatory transcripts included CXCL1, CXCL2, CXCL3, CXCL5, CXCL6, CXCL8, IL32, IL33, CSF2, TSLP, IL1A, IL6, IL18, VCAM1, ICAM1, IL18R1, IL1RL1, TNFSF4, TNFRSF4, TNFRSF8, ITGA2, ITGA4, and ITGAV. Furthermore, multiple cell cycle-related transcripts were induced with the combinations of LIGHT with IL-13 or IL-17. Providing physiological significance, some of the fibroblast transcriptional signatures induced by these cytokines were found to be present in subsets of fibroblasts isolated from patients with interstitial lung disease. This study highlights the synergistic activities of LIGHT in lung fibroblasts and suggests it could drive inflammatory activities relevant for several diseases dependent on the availability of other classical cytokines made in the lungs.