Comparison of the effects between catalase and superoxide dismutase on regulating macrophage inflammatory response and protecting osteogenic function of periodontal ligament cells.

Background: Reactive oxygen species (ROS) have been confirmed closely associated with the pathological process of periodontitis, but the specific roles played by different ROS types are still to be investigated. Catalase (CAT) and Superoxide dismutase (SOD) specifically eliminate hydrogen peroxide (HO) and superoxide anion (O), respectively. We for the first time compare the effects and mechanisms of CAT and SOD in protecting periodontal ligament cells (PDLCs) against oxidative damage, reducing the expression of macrophage inflammatory factors, and preserving the osteogenic differentiation function of PDLCs by modulating the inflammatory environment.

Methods: CAT or SOD in combination with lipopolysaccharide (LPS) were added to the culture medium of RAW 264.7 and PDLCs. The intracellular ROS level, lipid peroxidation and DNA damage were observed by confocal microscope. Inflammation levels were assessed by real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot. A co-culture system of macrophages and PDLCs was established, and the osteogenic differentiation of PDLCs was evaluated by alkaline phosphatase staining, alizarin red S staining, RT-qPCR and Western blot. Finally, differentially expressed genes (DEGs) in CAT and SOD were detected by RNA sequencing and the biological functions and signaling pathways involved were analyzed.

Results: CAT or SOD can effectively inhibit intracellular ROS levels, lipid peroxidation and DNA damage, as well as increase the levels of antioxidative molecules and decrease the levels of inflammatory factors. SOD increased the levels of antioxidative molecules more strongly, while CAT reduced inflammatory factors more effectively. The RNA sequencing results indicate that CAT exhibits stronger inhibitory effects on inflammation-related signaling pathways, which could account for the observed differences.

Conclusions: In this study, we observed differential antioxidant and anti-inflammatory effects between CAT and SOD, which may be associated with CAT's better inhibition of the activation of inflammatory pathways. Our study will provide scientific references for the future development of highly selective ROS- scavenging antioxidant drugs.