Platelet-Rich Fibrin Reduces IL-1β Release from Macrophages Undergoing Pyroptosis

Background: Pyroptosis is a catabolic process relevant to periodontal disorders for which interleukin-1 beta (IL-1 beta) inflammation is central to the pathophysiology of the disease. Despite platelet-rich fibrin (PRF) anti-inflammatory properties and its application to support periodontal regeneration, the capacity of PRF to modulate pyroptosis, specifically the production and release of IL-1 beta, remains unknown. The question arises whether PRF could regulate IL-1 beta release from macrophages in vitro. Methods: To answer this question, RAW 264.7 macrophages and primary macrophages obtained from murine bone marrow were primed with PRF before being challenged by lipopolysaccharide (LPS). Cells were then analysed for the pyroptosis signalling components by gene expression analyses and IL-1 beta secretion at the protein level. The release of mitochondrial reactive oxygen species (ROS) was also detected. Results: PRF lowered the LPS-induced expression of IL-1 beta and NLRP3 inflammasome, caspase-11 and IL-18 in primary macrophages, and IL-1 beta and caspase-11 in RAW 264.7 cells. Additionally, PRF diminished the secretion of IL-1 beta at the protein level in LPS-induced RAW 264.7 cells. This was shown through immunoassays performed with the supernatant and further confirmed by analysing the lysates of permeabilised cells. Furthermore, PRF reduced the ROS release provoked by LPS in RAW 264.7 cells. Finally, to enhance IL-1 beta release from the LPS-primed macrophages, we introduced a second signal with adenosine triphosphate (ATP). In this setting, PRF significantly reduced IL-1 beta release in RAW 264.7 cells and a trend to diminish IL-1 beta release in primary macrophages. Conclusion: These findings suggest that PRF can reduce IL-1 beta release and, at least in part, inhibit pyroptosis-related factors in LPS-challenged macrophages.

Automated summary

The study found that PRF can reduce IL-1β release and partially inhibit pyroptosis-related factors in LPS-challenged macrophages.