The Competition between the Decoy Receptor of IL-1 and IL1RL2 for the Co-Receptor of IL-1, Mediate Inhibition of the IL-36 Signalling.

Abstract

The proinflammatory interleukin (IL)-1 family plays a key role in immune system includes IL-1, IL-33 and IL-36 cytokines. NF-κB signalling pathway initiates by binding the agonist ligand with its specific receptor, type I IL-1 receptor (IL-1R1), suppressor of tumorigenicity 2 (ST2) and IL-1R related protein 2 (IL-1Rrp2), respectively. As they share the same co-receptor called IL-1R accessory protein (IL-1RAcP). Whereas the decoy receptor acts as a regulator such as IL-1R2 and the short form of ST2 (sST2) by binding with IL-1 without inducing cell signalling. In this study, we used three cell lines, human immortal keratinocyte (HaCaT), human colon cancer cell line (HT-29) and human epidermoid carcinoma line (A431). To examine the competitive IL-1R2 for the shared co-receptor IL-1RAcP and produces an inhibition effect on IL-36 signalling and whether we could assess the same impact on IL-33 as well. First, it was attempted to define the IL-36β response curve in absence of IL-1R1 and compare it with the curve response when IL-1β is added. Second, searching for ST2 transcripts (sST2 and ST2L) in the available cell lines by reverse transcription (RT) PCR. Finally, it was utilised CRISPR/Cas9 technique to provide with derivative cell lines with double knock-out (HT-29-DL) (IL-1R1⁻/IL-1R2⁻) and attempt to produce a deletion on IL-1R1 on A431 and HaCaT. Overall, we detected an inhibition effect on IL-36β signalling by IL-1β which was seen in sub-line of HT-29 IL-1R1 knock-out. While we could provide any evidence of the suppression impact on IL-33 because all available cells seem not be able to express ST2. Also, could not study whether this effect occurs because of trapping the IL-1RAcP by IL-1R2 when it binds with IL-1β. However, more research is required to understand the mechanism of inhibition.