Interleukin-1β and tumor necrosis factor-α augment acidosis-induced rat articular chondrocyte apoptosis via nuclear factor-kappaB-dependent upregulation of ASIC1a channel

Abstract

The acute-phase proinflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) demonstrate high-level expression and pleiotropic biological effects, and contribute to the progression and persistence of rheumatoid arthritis (RA). Acid hydrarthrosis is also an important pathological characteristic of RA, and the acid-sensing ion channel 1a (ASIC1a) plays a critical role in acidosis-induced chondrocyte cytotoxicity. However, the roles of IL-1β and TNF-α in acid-induced apoptosis of chondrocytes remain unclear. Rat adjuvant arthritis and primary articular chondrocytes were used as in vivo and in vitro model systems, respectively. ASIC1a expression in articular cartilage was increased and highly colocalized with nuclear factor (NF)-κB expression in vivo. IL-1β and TNF-α could upregulate ASIC1a expression. These cytokines activated mitogen-activated protein kinase and NF-κB pathways in chondrocytes, while the respective inhibitors of these signaling pathways could partially reverse the ASIC1a upregulation induced by IL-1β and TNF-α. Dual luciferase and gel-shift assays and chromatin immunoprecipitation-polymerase chain reaction demonstrated that IL-1β and TNF-α enhanced ASIC1a promoter activity in chondrocytes by increasing NF-κB DNA-binding activities, which was in turn prevented by the NF-κB inhibitor ammonium pyrrolidinedithiocarbamate. IL-1β and TNF-α also decreased cell viability but enhanced LDH release, intracellular Ca concentration elevation, loss of mitochondrial membrane potential, cleaved PARP and cleaved caspase-3/9 expression, and apoptosis in acid-stimulated chondrocytes, which effects could be abrogated by the specific ASIC1a inhibitor psalmotoxin-1 (PcTX-1), ASIC1a-short hairpin RNA or calcium chelating agent BAPTA-AM. These results indicate that IL-1β and TNF-α can augment acidosis-induced cytotoxicity through NF-κB-dependent up-regulation of ASIC1a channel expression in primary articular chondrocytes.

Factors and Molecular Mechanisms Influencing the Protein Synthesis, Degradation and Membrane Trafficking of ASIC1a

“…Our previous studies have indicated that extracellular acidosis increases protein expression of ASIC1a in a pH-and time-dependent manner in rat articular chondrocytes (Dai et al, 2017;Gao et al, 2019;Zu et al, 2020). Moreover, it has been reported that ASIC1a expression is significantly increased in the articular cartilage of adjuvant arthritis (AA) rats (Zhou et al, 2015), the articular synovial fluid of which showed a low pH value compared to that of the non-arthritic rat synovial fluid (Zhou et al, 2018). Furthermore, blocking ASIC1a expression through pretreatment with the ASIC1a-specific blocker such as psalmotoxinf (PcTx1) or ASIC1a RNA interference (RNAi) reversed the promoting effect of extracellular acidification on the protein and mRNA expression levels of ASIC1a and decreased cell death induced by extracellular acidosis (Gao et al, 2019).…”

“…Our recent studies have concentrated on determining the relationship between inflammatory cytokines and ASIC1a expression in rheumatoid arthritis (RA). The results showed that several pro-inflammatory cytokines, including interleukin-6 (IL-6) (Zhou et al, 2015), IL-1β (Zhou et al, 2018), and tumor necrosis factor-α (TNF-α) (Zhou et al, 2018) upregulate the levels of ASIC1a in a time-and dose-dependent manner in articular chondrocytes. Moreover, this effect was partially reversed by pretreating the cells with pyrrolidine dithiocarbamate (PDTC), an inhibitor of nuclear factor kappa B (NF-κB), indicating that pro-inflammatory cytokines induced the upregulation of ASIC1a in articular chondrocytes mainly through the NF-κB signaling pathway.…”

“…NF-κB is an evolutionarily conserved transcription factor involved in the expression of genes that play a critical role in various biological processes, including immune response, inflammation, proliferation, and apoptosis (Mitchell and Carmody, 2018). For instance, IL-1β and TNF-α play a role in ASIC1a protein synthesis through the NF-κB signaling pathway in the following ways (Zhou et al, 2018): (1) Co-expression of ASIC1a and NF-κB p65 was high in articular cartilage tissues, especially in AA rats, an experimental animal model of RA; (2) IL-1β or TNF-α increased the translocation of NF-κB p65 to the nucleus in a time-dependent manner; (3) IL-1β-or TNFα-induced ASIC1a expression was partially abrogated by PDTC; (4) IL-1β or TNF-α enhanced the activity of the ASIC1a gene promoter by increasing the DNA-binding activities of NF-κB, which could be inhibited by PDTC. These results demonstrate that NF-κB activation is involved in the synthesis of the ASIC1a protein induced by IL-1β or TNF-α.…”

Infrapatellar Fat Pad and Knee Osteoarthritis

“…Studies on these cytokines are exhaustive because of their important roles in inflammation. For example, IL-1β has been used to induce normal chondrocytes in the phenotype of OA chondrocytes in vitro [42], and the role of anti TNF-α targeted drugs has also been suggested as an option for treating arthritis [43].…”

Salidroside Suppresses IL-1β-Induced Apoptosis in Chondrocytes via Phosphatidylinositol 3-Kinases (PI3K)/Akt Signaling Inhibition

“…IL-1β levels are significantly higher in cartilage of patients with OA, which plays a key role in inducing cell apoptosis by increasing ROS production and NO release. It has been reported that IL-1β induces cell apoptosis in various cells, including intervertebral disc cells and chondrocytes [14,15]. In contrast, Salidroside has an anti-apoptotic effect on various type of cells [16].…”