The Expression of Inflammasomes NLRP1 and NLRP3, Toll-Like Receptors, and Vitamin D Receptor in Synovial Fibroblasts From Patients With Different Types of Knee Arthritis

Abstract

Activated rheumatoid arthritis (RA) synovial fibroblasts (SFs) are among the most important cells promoting RA pathogenesis. They are considered active contributors to the initiation, progression, and perpetuation of the disease; therefore, early detection of RASF activation could advance contemporary diagnosis and adequate treatment of undifferentiated early inflammatory arthritis (EA). In this study, we investigated the expression of nucleotide-binding, oligomerization domain (NOD)-like receptor family, pyrin domain containing (NLRP)1, NLRP3 inflammasomes, Toll-like receptor (TLR)1, TLR2, TLR4, vitamin D receptor (VDR), and secretion of matrix metalloproteinases (MMPs) in SFs isolated from patients with RA, osteoarthritis (OA), EA, and control individuals (CN) after knee surgical intervention. C-reactive protein, general blood test, anticyclic citrullinated peptide (anti-CCP), rheumatoid factor (RF), and vitamin D (vitD) in patients’ sera were performed. Cells were stimulated or not with 100 ng/ml tumor necrosis factor alpha (TNF-α) or/and 1 nM or/and 0.01 nM vitamin D3 for 72 h. The expression levels of NLRP1, NLRP3, TLR1, TLR2, TLR4, and VDR in all examined SFs were analyzed by quantitative real-time PCR (RT-qPCR). Additionally, the secretion of IL-1β by SFs and MMPs were determined by ELISA and Luminex technology. The expression of NLRP3 was correlated with the levels of CRP, RF, and anti-CCP, suggesting its implication in SF inflammatory activation. In the TNF-α-stimulated SFs, a significantly lower expression of NLRP3 and TLR4 was observed in the RA group, compared with the other tested forms of arthritis. Moreover, upregulation of NLRP3 expression by TNF-α alone or in combination with vitD3 was observed, further indicating involvement of NLRP3 in the inflammatory responses of SFs. Secretion of IL-1β was not detected in any sample, while TNF-α upregulated the levels of secreted MMP-1, MMP-7, MMP-8, MMP-12, and MMP-13 in all patient groups. Attenuating effects of vitD on the expression of NLRP3, TLR1, and TLR4 suggest potential protective effects of vitD on the inflammatory responses in SFs. However, longer studies may be needed to confirm or fully rule out the potential implication of vitD in SF activation in inflammatory arthritis. Both VDR and NLRP3 in the TNF-α-stimulated SFs negatively correlated with the age of patients, suggesting potential age-related changes in the local inflammatory responses.

Zhuifeng tougu capsules inhibit the TLR4/MyD88/NF-κB signaling pathway and alleviate knee osteoarthritis: In vitro and in vivo experiments

“…However, many research advances exist on the correlation between bone marrow lesions, synovitis, and OA ( Pauli et al, 2012 ; Coughlin and Kennedy, 2016 ; O’Neill and Felson, 2018 ). As inflammation is the core of the pathogenesis of OA ( Scanzello, 2017 ), including synovitis, innate immune mechanism, and the inherent inflammation of articular cartilage ( Sakalyte et al, 2021 ), it is the current research hotspot in OA. Furthermore, evidence reveals that the occurrence and development of OA are closely related to an autoimmune mechanism ( Barreto et al, 2020 ).…”

Dehydrocorydaline Accelerates Cell Proliferation and Extracellular Matrix Synthesis of TNFα-Treated Human Chondrocytes by Targeting Cox2 through JAK1-STAT3 Signaling Pathway

“…Inflammatory factors are expressed and secreted into the joint fluid, such as TNFα, IL-1α, IL-6, and IL-1β [30]. The pro-inflammatory factors further up-regulate MMP1, MMP7, MMP8, MMP12, and MMP13 expression and activation, accelerating OA progression and obstructing cartilage regeneration and repair [31]. In the current study, the results also confirmed that the IL-13 receptor, IL-20 receptor, Cox2, MMP3, and MMP13 are highly expressed in the TNFα-treated human chondrocytes (Figure 3D).…”

Vitamin D3 Supplementation Attenuates Surgery-Induced Neuroinflammation and Cognitive Impairment by Regulating NLRP3 Inflammasome in Mice

“…Overproduction of IL-1 β and IL-18 can result in chronic inflammation-related diseases, including POCD [ 9 , 10 ]. By inactivating the NLRP3 inflammasome in preclinical models, VD3 could attenuate osteoarthritis, periodontitis, and cutaneous inflammation [ 15 , 35 , 36 ]. This study demonstrated that NLRP3 inflammasome was upregulated in the hippocampus of aged mice following tibial fracture surgery and that this process was inhibited by VD3 pretreatments.…”