RNA-seq of THP-1 and U937 exposed to enamel matrix derivative

Objectives: Enamel matrix derivatives (EMDs) are applied in periodontal defects and gingival recession, a process where macrophages contribute to the clinical outcome. There is a need for standardized bioassays to better understand and monitor how EMD affects macrophages in vitro. Materials and methods: We propose using THP-1 and U937, both widely established monocytic cell lines, as bioassays in EMD research. Both cell lines have different origins, as THP-1 is a leukemia cell line, and U937 originates from the pleural effusion of a patient with histiocytic lymphoma. To understand their differential response to EMD, we employed an RNA-seq approach revealing changes in the genetic signatures of THP-1 and U937 cells. Results: When applying a threshold of 1.5 log2 fold-change and a significance of 2.0-log10, we could identify 5/37 and 30/23 up- and down-regulated genes in THP1 and U937 cells, respectively. In THP-1, the upregulated genes included S100A8, S100A9 and CD38; downregulated gene included ADM, CD48, IL24, MMP1, and PDGFB. In U937, most striking was the increase of alpha subunit integrins ITGA1, ITGA2, ITGA6, and the decrease of genes including OLR1, CCL1, CCL4L2, CCL8, IL21R, MMP7, PDGFB and MMP25. We further show that the TGF-β receptor type I kinase inhibitor SB431542 blocked the expression changes of S100A8, S100A9, CD38, ITGA2, ITGA6, and OLR1 but failed to reverse PDGFB. Conclusions: These data serve as a primer for developing macrophage bioassays to measure EMD activity in the context of TGF-β signaling. Clinical relevance : To identify a panel of genes, ideally being strongly regulated by EMD, in established THP1 and U937 cell lines, with a potential clinically relevant function in periodontal and peri-implant regeneration. Clinical trial number: Not applicable.