IL-34 modulates rheumatoid synovial fibroblast proliferation and migration via ERK/AKT signalling pathway

No Thumbnail Available
A. Elkhider
J. Wei
M. AL-Azab
Y. Tang
W. Walana
W. Li
B. Yuan
Y. Ye
G. Wang
Y. Zhang
Journal Title
Journal ISSN
Volume Title
Objective The interface between pro-inflammatory cytokines and rheumatoid synovial fibroblast (sF LS) has central effects on rheumatoid arthritis (RA). The present study aimed to explore the role of IL-34 expression as one of major cytokine implicated in RA. Methods We examined the expression of IL-34 after RA sF LS stimulated by IL-1B and TGF-B1 separately by reverse transcription polymerase chain reaction (RT-PCR). Transwell and wound closure techniques were used to detect whether IL-34 is involved in promoting cell migration. Cellular viability was determined via CCK-8 and cultural morphology assays between IL-34 downregulated group and non-transfected counterpart. We also tested the expression of VEGF gene with RT-PCR analysis and activation of the major signalling pathways by western blot in IL-34 down-regulated group, IL-16 or TGF-{1 treated groups. Propidium iodide (PI) staining and fluoresceine isothiocyanate (FITC) Annexin V and propidium iodide apoptosis assay were used to analyse cell cycle arrest and apoptosis separately in IL-34 down-regulated cells. Results We found that IL-1f significantly enhanced IL-34 expression, while contrarily, TGF -(1 restrained IL-34 gene expression. Transwell and wound closure techniques showed that IL-34 was involved considerably in promoting cell migration. However, IL-34 knock-down restricted sFLS migration possibly through the diminishing of MMP2 and MMP9 expression. Interestingly, IL-34 down-regulated cells exhibited significantly low cellular viability compared with the non-transfected counterpart via CCK-8 and cultural morphology assays. We found that IL-34 down-regulated cells have low VEGF gene expression compared with treated cells. PI staining showed a GO/GI cell cycle arrest in IL-34 down-regulated cells. FITC Annexin V and propidium iodide apoptosis assay verified that IL-34 down-regulated cells induced massive apoptosis through apoptotic signalling caspase3, while IL-1f treated cells presented termination of cellular apoptosis signalled by BCL-2. Furthermore, we observed IL-34 induced activation of ERK1/2 and AKT pathways while IL-34 down-regulation significantly decreased the activation of these pathways.
Elkhider, A., Wei, J., Al-Azab, M., Tang, Y., Walana, W., Li, W., Yuan, B., Ye, Y., Wang, G., Zhang, Y. and Li, X., 2020. ILS34 modulates rheumatoid synovial fibroblast proliferation and migration via ERK/AKT signalling pathway. Clinical and experimental rheumatology, 38, pp.479-487.
Walana, W., Wang, J.J., Yabasin, I.B., Ntim, M., Kampo, S., Al-Azab, M., Elkhider, A., Kuugbee, E.D., Cheng, J.W., Gordon, J.R. and Li, F., 2018. IL-8 analogue CXCL8 (3-72) K11R/G31P, modulates LPS-induced inflammation via AKT1-NF-kβ and ERK1/2-AP-1 pathways in THP-1 monocytes. Human Immunology, 79(11), pp.809-816.