Gasdermin-E Mediated Pyroptosis—A Novel Mechanism Regulating Migration, Invasion and Release of Inflammatory Cytokines in Rheumatoid Arthritis Fibroblast-like Synoviocytes

Abstract

Synovium fibroblast-like synoviocytes (FLSs) are important participants in the pathogenesis of synovitis and joint destruction in rheumatoid arthritis (RA). Pyroptosis is a pro-inflammatory and cell lytic programmed cell death mechanism mediated by gasdermin (GSDM) family proteins. In this study, we demonstrated the increased expression of GSDME and increased levels of GSDME-mediated pyroptosis in RA synovial tissues. In vitro, stimulation with TNF-α plus hypoxia mimicking the inflammatory and hypoxic environment in RA synovium induced GSDME-mediated pyroptosis in RA-FLSs in combination with the promotion of migration and invasion abilities and the release of inflammatory cytokines (IL-6, IL-8). Moreover, knockdown of GSDME significantly inhibited the proliferation rate, migration/invasion effects and cytokines released through the reduction of GSDME-mediated pyroptosis. The immunohistochemistry results showed that RA patients with high GSDME N-terminal (GSDME-NT) expression, which is the active form of GSDME, showed higher IL-6 expression in both lining and sublining layer of synovium than that in patients with low GSDME-NT expression, osteoarthritis and non-inflammatory orthopedic arthropathies. Our findings revealed a novel mechanism regulating cell proliferation, migration, invasion and inflammatory cytokines release during the process of GSDME mediated pyroptosis in RA.

Targeting inflammasome-dependent mechanisms as an emerging pharmacological approach for osteoarthritis therapy

“… 26 Similarly, Gasdermin E (GSDME) level is reported to be upregulated in the synovial macrophages and synovial fibroblasts of OA and RA synovium and its deficiency mitigated synovitis in mouse models of RA. 74 , 75 In addition, we speculated a role for Gasdermin C (GSDMC) in OA as its upstream regulator, caspase-6, 76 was shown to be upregulated in chondrocytes exposed to mechanical stress in the ACLT rat osteoarthritis model. 77

Figure 5 Pyroptotic pathways related to OA The canonical pyroptotic pathway involves the activation of caspase-1 activity leading to the cleavage of GSDMD through the activation of nod-like receptor (NLR) proteins.

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Pyroptosis in inflammatory bone diseases: Molecular insights and targeting strategies

“…These two signaling pathways, which are responsible for the cleavage of GSDME and GSDMD, might mutually support one another. For the caspase‐3/GSDME axis, TNF‐α in combination with hypoxia could induce pyroptosis via this pathway 120 . The role of TNF in activating pyroptosis in RA via the caspase‐3/GSDME signaling pathway was again confirmed by Zhai et al 121 …”

“…For the caspase-3/GSDME axis, TNF-α in combination with hypoxia could induce pyroptosis via this pathway. 120 The role of TNF in activating pyroptosis in RA via the caspase-3/GSDME signaling pathway was again confirmed by Zhai et al 121 Moreover, Wu et al 122 found that acid-sensitive ion channels (ASICs) mediated pyroptosis in chondrocytes taken from rats with adjuvant arthritis. The underlying process may be connected to the capacity of ASIC1a to encourage the influx of Ca 2+ to initiate the calpain-2/ calcineurin axis, which ultimately activates caspase-1 after contributing to the aggregation and assembly of the NLRP3 inflammasome.…”

“…Nrf2/HO-1 axis inhibits NF-κB pathway to attenuate pyroptosis 88 SDF-1 activates AMPK signal to suppress NLRP3 inflammasome and subsequent pyroptosis 89 A3AR inhibits the ROS/NLPR3/GSDMD axis to relieve pyroptosis-mediated symptoms in OA 90 Osteomyelitis NLRP3 inflammasome is activated to cause bone loss 93 Periodontitis Hypoxia with P. gingivalis-LPS synergistically activate NLRP3 to induce pyroptosis 101 MARK4 induces NLRP3-mediated pyroptosis 102 The Nrf2/HO-1 axis inhibits LPS-induced ROS to prevent NLRP3-mediated pyroptosis 98 NLRP6 inflammasome activates caspase-1 to induce pyroptosis of HGFs 103 Caspase-4/GSDMD pathway mediates noncanonical pyroptosis 104,105 Butyrate activates caspase-3/GSDME axis to induce pyroptosis 106 LPS-induced Dec1 upregulates NF-κB via the PI3K/AKT pathway to promote pyroptosis, while LPS-induced Dec2 attenuates the phosphorylation of NF-κB to inhibit pyroptosis [108][109][110][111] RA TNF-α plus CRT induces NLRP3 inflammasome-mediated pyroptosis 116 ACPAs induces NLRP3 inflammasome-mediated pyroptosis via the Akt/NF-κB axis 117 S100A9 may participate in the IL-6-induced pyroptosis via activating the CTSB/ATP pathway 118 Hypoxia induces NLRP3 inflammasome-mediated pyroptosis via the ROS/GRK2/HIF-1α axis 119 TNF-α plus hypoxia induce caspase-3/GSDME-mediated pyroptosis 120 ASIC1a promotes the influx of Ca 2+ , activating the calpain/calcineurin axis to induce NLRP3 inflammasome-mediated pyroptosis 122,123 CaSR promotes the influx of Ca 2 to induce NLRP3 inflammasome-mediated pyroptosis 124 Abbreviations: ACPAs, anti-citrullinated protein antibodies; AP, apical periodontitis; ASIC1a, acid-sensitive ion channel 1a; ATP, adenosine triphosphate; A3AR, adenosine A3 receptor; CaSR, calcium-sensing receptor; CRT, calreticulin; CTSB, cathepsin B; Dec1, embryo-chondrocyte expressed genes 1; FLS, fibroblast-like synoviocyte; Gout, gouty arthritis; GRK2, G protein-coupled receptor kinase 2; GSDMD, gasdermin D; HGFs, human gingival fibroblasts; HIF-1α, hypoxia-inducible factor-1α; HO-1, heme oxygenase-1; IL, interleukin; LPS, lipopolysaccharide; MARK4, microtubule affinity regulating kinase 4; NF-κB, nuclear factor kappa-B; NLRP3, nucleotide-binding oligomerization domain receptor family PYD domain containing 3; NOX, NAD(P)H oxidases; Nrf2, nuclear factor erythroid-2-related factor 2; OA, osteoarthritis; P. gingivalis, Porphyromonas gingivalis; ROS, reactive oxygen species; SDF-1, stromal cell-derived factor-1; TNF-α, tumor necrosis factor-α; USP7, ubiquitin-specific protease 7.…”

Recent Therapeutic Strategies for Excessive Chondrocyte Death in Osteoarthritis: A Review

“…A little more accurately, programmed‐mediated cell death can be classified into two forms: lytic and non‐lytic cell death. Lytic cell death often consists of necroptosis and pyroptosis that can cause leakage of intracellular components, promote release of inflammatory cytokines, and lead to following inflammatory response, which is known as inflammatory death or inflammatory necrosis 12,13 . And non‐lytic cell death (usually referred to as apoptosis) manifests when cells can be eliminated by phagocytes but without an inflammatory response 14 .…”