NCOA4‐mediated ferritinophagy promoted inflammatory responses in periodontitis

Abstract

Background/Objectives Iron homeostasis plays a crucial role in the combat against pathogen invasion. Ferrous iron can trigger generous production of reactive oxygen species (ROS) by Fenton reaction. Nuclear receptor coactivator 4 (NCOA4), a selective cargo receptor to deliver ferritin to lysosome, may trigger release of ferritin‐bound iron into the cytosol. The aim of the present study was to explore whether NCOA4‐mediated ferritinophagy participated in the pathogenesis of periodontitis, and its role in promoting the periodontal inflammation. Methods Inflamed and healthy periodontal tissues were harvested for immunobiological staining of ferritinophagy‐related genes in the periodontal tissues, while real‐time quantitative PCR (qPCR) was utilized to detect mRNA transcription. Periodontal ligament fibroblasts (PDLFs) were isolated and infected with Porphyromonas gingivalis. The mRNA transcription and protein expression of genes involved in the iron metabolism, including NCOA4, transferrin receptor 1 (TFR1), and ferroportin (SLC40A1) were detected by qPCR and western blot. Levels of labile iron pool and ROS production were detected by flow cytometry and confocal endoscopy. Small interference RNA was utilized to knock down NCOA4. Results Elevated expression of NCOA4, ferritin heavy chain, and light chain were observed in the diseased periodontal tissues. P. gingivalis infection promoted expression of TFR1, NCOA4, and microtubule‐associated protein 1‐light chain 3 B (LC3B), enhanced levels of intracellular labile iron pool and ROS production. NCOA4 knockdown reduced ROS generation in PDLFs in response to P. gingivalis and mitigated production of pro‐inflammatory monocyte chemoattractant protein‐1 and interleukin 6. P. gingivalis triggered activation of c‐Jun N‐terminal kinase (JNK) and p38 mitogen‐activated protein kinase signaling pathway. In addition, inhibitors of JNK, SP600125, and inhibitors of p38, SB203580 blocked NCOA4 transcription. Conclusion NCOA4‐ferritinophagy participated in the progress of periodontitis progression. P. gingvalis‐triggered ferritinophagy aggravated production of ROS and inflammatory responses in PDLFS. These findings suggest iron homeostasis plays an important role in the pathogenesis of periodontitis.

Ferroptosis: A New Development Trend in Periodontitis

“…Both animal experiments and clinical experiments have shown that the iron content in periodontitis sites was higher than that in healthy periodontal sites [ 68 ]. It has been reported that free iron concentrations are significantly up-regulated 6–12 h after periodontal infection [ 86 ], and these high concentrations of iron have been shown to be more favorable for the maturation of certain periodontal-dominant pathogenic bacteria biofilms [ 87 ]. To satisfy their growth and reproduction, micro-organisms need to compete with their hosts for iron.…”

Role of ferroptosis-related genes in periodontitis based on integrated bioinformatics analysis

“…Based on the RNA-seq, Davanian H confirmed that the elevated levels of locally produced cytokines in the periodontium [ 24 ]. A recent study including molecular biology experiments showed that NCOA4, one of the FRGs, is related to the occurrence and development of periodontitis, indicating that iron homeostasis plays an important role in the pathogenesis of periodontitis [ 20 ]. Ferroptosis triggers excess intracellular ROS and promotes lipid peroxidation, which is critical for inflammation.…”

“…We also found that the analysis results of the downregulated genes include NCOA4, which is important in periodontitis. An article pointed out that periodontitis is mostly correlated with NCOA4 -mediated ferritinophagy in intracellular iron level regulation [ 20 ], p38/hypoxia inducible factor-1α pathway activation, and bromodomain-containing protein 4 and cyclin-dependent kinase 9 transcription modulation mediated butyrate-triggered NCOA4 expression in periodontal ligament fibroblasts [ 19 ]. Conversely, NCOA4 over-expression increased sensitivity to ferroptosis [ 38 ].…”

“…the occurrence and development of periodontitis, indicating that iron homeostasis plays an important role in the pathogenesis of periodontitis [20]. Ferroptosis triggers excess intracellular ROS and promotes lipid peroxidation, which is critical for inflammation.…”

“…Based on the results of previous studies [ 19 , 20 ], we designed the present study to analyze the effects of ferroptosis on periodontitis using bioinformatics methods and found that there is a clear association between ferroptosis and periodontitis.…”