Caspase-3 and gasdermin E mediate macrophage pyroptosis in periodontitis.

Periodontitis is a chronic inflammatory disease linked to pyroptosis, an inflammatory cell death process. Macrophages are essential for maintaining microenvironment homeostasis, which is crucial for periodontal health. This study explores the mechanisms underlying the relationship between macrophage pyroptosis and periodontitis. Expression of the pyroptosis marker gasdermin E (GSDME) and the macrophage surface marker CD68 was examined by immunofluorescence double staining in healthy and periodontitis gingival tissues. In an in vitro pyroptosis model, RAW264.7 cells were irritated using Porphyromonas gingivalis-lipopolysaccharide (P. gingivalis-LPS) after treatment with either a nuclear factor kappa-B (NF-κB) agonist or inhibitor. The mRNA and protein levels of NF-κB, caspase-3, GSDME, and interleukin-1β (IL-1β) were evaluated through qRT-PCR, western blotting, and ELISA techniques. GSDME and CD68 were heavily elevated in inflamed gingival tissues compared to healthy tissues and co-localized in the same region. Furthermore, exposure to P. gingivalis-LPS resulted in a significant upregulation of NF-κB, caspase-3, GSDME, and IL-1β at both the mRNA and protein levels in RAW264.7 cells. NF-κB agonist or inhibitor pretreatment enhanced or inhibited these effects. GSDME-mediated macrophage pyroptosis is implicated in periodontitis. Based on in vitro experiments, P. gingivalis-LPS causes pyroptosis in RAW264.7 cells through the caspase-3/GSDME pathway. Furthermore, NF-κB regulates this pyroptotic pathway.

Gao X ，Li S ，Wang W ，Zhang X ，Yu X ，Fan C ，Li W ，Yang C ，Wang L ，Ji Q ... -  《-》

Isoliquiritigenin alleviates P. gingivalis-LPS/ATP-induced pyroptosis by inhibiting NF-κB/ NLRP3/GSDMD signals in human gingival fibroblasts.

To investigate whether pyroptosis is induced by Porphyromonas gingivalis-lipopolysaccharide (P. gingivalis-LPS)/ adenosine triphosphate (ATP) through NF-κB/NLRP3/GSDMD signaling in human gingival fibroblasts (HGFs) and whether isoliquiritigenin (ISL) alleviates pyroptosis by inhibition of NF-κB/NLRP3/GSDMD signals. Periodontitis was optimally simulated using a combination of P. gingivalis-LPS and ATP. The expression levels of genes and proteins of NF-κB, NLRP3 inflammasome, GSDMD, and IL-1β was characterized by qRT-PCR, western blotting and ELISA. The 2',7'‑dichlorodihydrofluorescein diacetate fluorescence probe was used to determine the intracellular ROS level. Hoechst 33342 and PI double staining, cytotoxicity assay, and caspase-1 activity assay were used to confirm the influence of ISL on pyroptosis in P. gingivalis-LPS/ATP-treated HGFs. P. gingivalis-LPS/ATP stimulation significantly promoted expression of NF-κB, the NLRP3 inflammasome, GSDMD, and IL-1β at gene and protein levels. The proportion of membrane-damaged cells, caspase-1 activity, and the release of lactate dehydrogenase (LDH) were also elevated. However, pretreatment with ISL observably suppressed these effects. P. gingivalis-LPS/ATP induced pyroptosis in HGFs by activating NF-κB/NLRP3/GSDMD signals and ISL attenuated P. gingivalis-LPS/ATP-induced pyroptosis by inhibiting these signals. This evidence may provide a new direction for the treatment of periodontitis.

Lv X ，Fan C ，Jiang Z ，Wang W ，Qiu X ，Ji Q ... -  《-》

Gasdermin E-mediated keratinocyte pyroptosis participates in the pathogenesis of psoriasis by promoting skin inflammation.

Psoriasis is a common chronic inflammatory disease with an unclear aetiology. Keratinocytes in psoriasis are susceptible to exogenous triggers that induce inflammatory cell death. To investigate whether gasdermin E (GSDME)-mediated pyroptosis in keratinocytes contributes to the pathogenesis of psoriasis. Skin samples from patients with psoriasis and from healthy controls were collected to evaluate the expression of GSDME, cleaved caspase-3 and inflammatory factors. We then analysed the data series GSE41662 to further compare the expression of GSDME between lesional and nonlesional skin samples in those with psoriasis. In vivo, a caspase-3 inhibitor and GSDME-deficient mice (Gsdme-/-) were used to block caspase-3/GSDME activation in an imiquimod-induced psoriasis model. Skin inflammation, disease severity and pyroptosis-related proteins were analysed. In vitro, tumour necrosis factor (TNF)-α-induced caspase-3/GSDME-mediated pyroptosis in the HACAT cell line was explored. Our analysis of the GSE41662 data series found that GSDME was upregulated in psoriasis lesions vs. normal skin. High levels of inflammatory cytokines such as interleukin (IL)-1β, IL-6 and TNF-α were also found in psoriasis lesions. In mice in the Gsdme-/- and caspase-3 inhibitor groups, the severity of skin inflammation was attenuated and GSDME and cleaved caspase-3 levels decreased after imiquimod treatment. Similarly, IL-1β, IL-6 and TNF-α expression was decreased in the Gsdme-/- and caspase-3 inhibitor groups. In vitro, TNF-α induced HACAT cell pyroptosis through caspase-3/GSDME pathway activation, which was suppressed by blocking caspase-3 or silencing Gsdme. Our study provides a novel explanation of TNF-α/caspase-3/GSDME-mediated keratinocyte pyroptosis in the initiation and -acceleration of skin inflammation and the progression of psoriasis.

Li Y ，He Y ，Yang F ，Liang R ，Xu W ，Li Y ，Cheng J ，Liang B ，Tang M ，Shi X ，Zhuang J ，Luo M ，Li L ，Zhang R ，Liu H ，Jie H ，Li X ，Han X ，Sun E ，Zhai Z ... -  《-》

Effects of amyloid β (Aβ)42 and Gasdermin D on the progression of Alzheimer's disease in vitro and in vivo through the regulation of astrocyte pyroptosis.

Hong W ，Hu C ，Wang C ，Zhu B ，Tian M ，Qin H ... -  《Aging-US》

Palmitic acid induces GSDMD-mediated pyroptosis in periodontal ligament cells via the NF-κB pathway.

Obesity can affect periodontal tissues and exacerbate periodontitis. Pyroptosis, a newly identified type of inflammatory cell death, is involved in the development of periodontal inflammation. The saturated fatty acid palmitic acid (PA) is elevated in obese patients. The effect of PA on pyroptosis in periodontal ligament cells (PDLCs) and its underlying mechanisms remain unknown. Human PDLCs were isolated from healthy individuals and cultured for experiments. The effects of PA on PDLC pyroptosis and the underlying mechanisms were examined by transmission electron microscopy, quantitative real-time PCR and western blotting. The morphology of PDLCs in the PA group indicated pyroptotic characteristics, including swollen cells, plasma membrane rupture and changes in subcellular organelles. PA induced inflammatory responses in PDLCs, as indicated by an increase in IL-1β in the cell culture supernatant. Furthermore, we found that the pyroptosis-related proteins caspase-1, caspase-4 and GSDMD were involved in PA-induced cell death. GSDMD and caspase-4 inhibitors alleviated pyroptotic death of PDLCs. Moreover, PA promoted NF-κB P65 phosphorylation. A NF-κB inhibitor decreased IL-1β expression and partly rescued cell death induced by PA. PA activated the NF-κB pathway and induced the inflammatory response in PDLCs. Caspase-4/GSDMD mediated PDLC pyroptosis induced by PA.

Sun BJ ，Chen MH ，Zhang WH ，Zhao BJ ，Zhang MH ，Han XX ，Yu LM ，Liu YH ... -  《-》