BACKGROUND:Host immune response triggered by plaque biofilm is an initiator of periodontitis progression and destruction.Macrophages are an important component of the innate immune response,which play an important role in inflammation occurrence and development. OBJECTIVE:To review the relationship between macrophage polarization and periodontitis and the related progress in the treatment of periodontitis by regulating macrophage polarization. METHODS:PubMed and CNKI databases were searched for relevant literature published from 1990 to 2023,with"macrophage polarization,M1/M2 macrophage,periodontitis,periodontitis treatment,macrophage polarization and periodontitis,osteoimmunology,ferroptosis,macrophage polarization and ferroptosis,periodontitis and ferroptosis"as the English and Chinese search terms.After the initial screening,96 articles were selected for review. RESULTS AND CONCLUSION:The switch between different phenotypes of macrophages is closely related to the tissue destruction caused by periodontitis,and various cytokines and inflammatory mediators secreted from macrophages are involved in the destruction and repair of periodontal tissue.Therefore,regulation of macrophage polarization and cytokine secretion in inflammatory state helps to alleviate periodontitis inflammation and improve the periodontal microenvironment,thereby reducing tissue destruction or promoting periodontal tissue regeneration.Many studies have been conducted to develop drugs or biomaterials to modulate macrophage function for the purpose of immunomodulatory treatment of periodontitis.However,macrophages act throughout the development of periodontitis and play an important role in the process of anti-infection,bone destruction and bone repair,and polarization is a complex and dynamic process influenced by many factors.Therefore,further exploration on possible mechanisms is still needed to clarify the interaction between materials or drugs and macrophages.

Primary hepatocytes are widely used in drug metabolism and toxicity assessment. As the culture of primary hepatocytes in vitro is a process of dedifferentiation, hepatocytes lose normal metabolic detoxification function gradually. The mechanism of hepatocyte dedifferentiation has been not clear so far. TFs play an important role in the dedifferentiation and non-parenchymal cells can maintain the function of hepatocytes in vitro. However, the current methods cannot be used in effective identification and quantitative analysis of a large number of TFs. In this paper, the mo-culture system (only primary hepatocytes) and co-culture system (primary hepatocytes and non-parenchymal cells) were established. The cells were cultured for 24 h, 48 h, 72 h as monolayer. The changes of TFs during the culture were obtained by TOT (Transcription factor response elements on tip) transcription factor enrichment method and mass spectrometry. A total of 219 TFs were identified in three individual replicates. The result revealed that up-regulated TFs were enriched in cell proliferation, death and immune response pathways, and down-regulated TFs were involved in metabolism pathway. The establishment of such culture-TFs identification system is of great significance to reveal the mechanism of primary hepatocyte dedifferentiation and crosstalk between hepatocytes and non-parenchymal cells.

Objective:To study the effects of periodontitis on bone and tryptophan metabolism of gut microbiota in the context of estrogen deficiency.Methods:Thirty-two female C57BL6/J mice were randomly divided into four groups based on table of random numbers ( n=8 in each group): Sham group, in which mice were given sham surgery; Sham_Lig group, in which mice were given sham surgery and were induced to periodontitis by ligating the bilateral maxillary second molars with 5-0 silk threads at the fourth week; Ovx group, in which mice were given bilateral ovariectomy; Ovx_Lig group, in which mice were given bilateral ovariectomy and were induced to periodontitis at the fourth week. After 8 weeks of ligation, the mice of 4 groups were euthanized for collecting the samples of femur, tibia, mandible and skull. Those samples were scanned by micro-CT to measure the bone mineral density (BMD), bone volume versus total volume ratio (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th) and trabecular spacing (Tb.Sp). The cecum contents of 4 groups of mice were collected for gut microbiota 16S rRNA gene sequencing. The tryptophan and its metabolites in intestinal tracts were detected by liquid chromatography-mass spectrometry. Pearson correlation analysis was performed to analyze the correlation between the abundance of gut microbiota and the content of tryptophan and its metabolites. Results:Femur BMD [(82.23±3.97) mg/cm 3], BV/TV [(9.25±1.37)%] and Tb.Th [(70.95±5.70) μm] in Ovx_Lig group were significantly lower than Ovx group [(96.30±3.76) mg/cm 3 ( P=0.004); (14.45±1.55)% ( P=0.022) and (87.58±8.02) μm ( P<0.001), respectively]. The β-diversity analysis of gut microbiota based on Bray-Curtis distance showed that samples of Ovx_Lig group and Ovx group were obviously grouped. Linear discriminant analysis effect size (LEfSe) showed that Alistipes was the representative genus in Ovx_Lig group. The relative abundance of Alistipes in Ovx_Lig group [(0.42±0.14)%] were significantly higher than that in Ovx group [(0.17±0.05)%] ( t=4.45, P<0.001). Tryptophan metabolism analysis showed that the content of kynurenic acid [(531.12±158.60) ng/g] in Ovx_Lig group were significantly higher than that in Ovx group [(400.42±57.96) ng/g] ( t=2.19, P=0.046). And the content of indole-3-carbaldehyde [(383.37±144.06) ng/g] in Ovx_Lig group were significantly lower than Ovx group [(701.72±141.93) ng/g] ( t=4.45, P<0.001). Correlation analysis showed that relative abundance of Alistipes was positively correlated with kynurenic acid ( r=0.32, P=0.088), while negatively correlated with indole-3-carbaldehyde ( r=-0.32, P=0.088). Conclusions:Periodontitis can induce bone destruction of femur in estrogen-deficient mice, the mechanism of which may be related to Alistipes in gut and the tryptophan metabolites kynurenic acid and indole-3-carbaldehyde.

Periodontitis and rheumatoid arthritis (RA) are chronic inflammatory diseases that share similar inflammatory mechanisms and characteristics. Programmed cell death (PCD) has recently garnered attention for its crucial role in regulating inflammation and maintaining tissue homeostasis, as well as for its potential to link these two diseases. The various forms of PCD--including apoptosis, pyroptosis, and necroptosis--are closely controlled by signaling pathways such as Toll-like receptor 4 (TLR4) /NF-κB and MAPK. These pathways determine cell fate and influence inflammatory responses, tissue destruction, and repair, and they both play important roles in the pathogenesis of RA and periodontitis. In periodontitis, periodontal pathogens such as Porphyromonas gingivalis (P. gingivalis) and its virulence factors, including lipopolysaccharide (LPS), induce pyroptosis and necroptosis in immune cells such as macrophages via the TLR4/NF-κB pathway, which leads to an excessive release of pro-inflammatory cytokines such as interleukin (IL)-1β and tumor necrosis factor (TNF)-α. Concurrently, these pathogens inhibit the normal apoptotic process of immune cells, such as neutrophils, prolonging their survival, exacerbating immune imbalance, and aggravating periodontal tissue destruction. Similarly, in RA synovial tissue, fibroblast-like synoviocytes (FLS) acquire apoptosis resistance through signaling pathways such as the Bcl-2 family, JAK/STAT, and NF-κB, allowing for the consistent proliferation and secretion of matrix metalloproteinases and pro-inflammatory cytokines. Meanwhile, the continuous activation of pyroptotic pathways in neutrophils and macrophages results in the sustained release of IL-1β, further exacerbating synovial inflammation and bone destruction. Notably, dysregulated PCD fosters inter-organ crosstalk through shared inflammatory mediators and metabolic networks. Damage-associated molecular patterns (DAMPs) and cytokines that originate from periodontal lesions can spread systemically, influencing cell death processes in synovial and immune cells, thereby aggravating joint inflammation and bone erosion. By contrast, systemic inflammation in RA can upregulate osteoclastic activity or interfere with the normal apoptosis of periodontal cells via TNF-α and IL-6, ultimately intensifying periodontal immune imbalance. This review highlights the pivotal bridging role of PCD in the pathogenesis of both periodontitis and RA, providing a reference for therapeutic strategies that target cell death pathways to manage and potentially mitigate these diseases.