Synovial Cell Migration is Associated with B Cell Activating Factor Expression Increased by TNFα or Decreased by KR33426

Redefinition of Synovial Fibroblasts in Rheumatoid Arthritis

The breakdown of immune tolerance and the rise in autoimmunity contribute to the onset of rheumatoid arthritis (RA), driven by significant changes in immune components. Recent advances in single-cell and spatial transcriptome profiling have revealed shifts in cell distribution and composition, expanding our understanding beyond molecular-level changes in inflammatory cytokines, autoantibodies, and autoantigens in RA. Surprisingly, synovial fibroblasts (SFs) play an active immunopathogenic role rather than remaining passive bystanders in RA, with notable alterations in their subpopulation distribution and composition. This study examines these changes in SF heterogeneity, assesses their impact on RA progression, and elucidates the immune characteristics and functions of SF subsets in the RA autoimmunity, encompassing both intrinsic and adaptive immunity. Additionally, this review discusses therapeutic strategies targeting immune SF subsets, highlighting the potential of future interventions in SF phenotypic reprogramming. Overall, this review redefines the role of SFs in RA and suggests targeting SF phenotypic reprogramming and its upstream molecules as a promising therapeutic approach to restore immune balance and modulate immune tolerance in RA.

Rosmarinic acid alleviates acetaminophen-induced hepatotoxicity by targeting Nrf2 and NEK7-NLRP3 signaling pathway

Rosmarinic acid (RA) is a natural polyphenol with various biological activities, such as anti-oxidative, anti-fibrotic, and hepatoprotective properties. The objective of this study was to investigate the protective effect of RA against acetaminophen (APAP)-induced hepatotoxicity (AILI) and explore the underlying mechanisms. Kunming mice were treated with RA (20, 40, or 80 mg/kg, i.g) for 7d, followed by an intraperitoneal injection of APAP (500 mg/kg). The liver injury was evaluated by serum biochemical and liver histopathological examinations. Human HepG2 cells were pre-treated with RA (20, 40, or 80 μmol/L) and then incubated with APAP (25 mmol/L) for 24 h. The MTT assay, wound healing assay, transwell migration assay, flow cytometry, and western blotting were employed to further evaluate RA's protective effects on AILI and explore the mechanisms. The results indicated that RA pre-treatment lowered the serum ALT and AST levels, ameliorated the histological damage to the liver, and reduced ROS generation and the production of IL-1β and IL-18 in the liver tissues in APAP-treated mice. Moreover, pre-treatment with RA could promote the cell viability and migration ability and inhibit apoptosis in APAP-treated HepG2 cells. Mechanistically, RA could significantly suppress the APAP-induced activation of the NEK7-NLRP3 signaling pathway. Notably, depletion of Nrf2 by short hairpin RNA (shRNA) partly eliminated the protective effects of RA on AILI and the suppression of NEK7-NLRP3 signaling by RA. In summary, these results indicate that RA has a protective role against AILI through Nrf2-mediated inhibition of ROS production and suppression of the NEK7-NLRP3 pathway.

Loss of EMP2 Inhibits Melanogenesis of MNT1 Melanoma Cells via Regulation of TRP-2

Melanogenesis is the production of melanin from tyrosine by a series of enzyme-catalyzed reactions, in which tyrosinase and DOPA oxidase play key roles. The melanin content in the skin determines skin pigmentation. Abnormalities in skin pigmentation lead to various skin pigmentation disorders. Recent research has shown that the expression of EMP2 is much lower in melanoma than in normal melanocytes, but its role in melanogenesis has not yet been elucidated. Therefore, we investigated the role of EMP2 in the melanogenesis of MNT1 human melanoma cells. We examined TRP-1, TRP-2, and TYR expression levels during melanogenesis in MNT1 melanoma cells by gene silencing of EMP2. Western blot and RT-PCR results confirmed that the expression levels of TYR and TRP-2 were decreased when EMP2 expression was knocked down by EMP2 siRNA in MNT1 cells, and these changes were reversed when EMP2 was overexpressed. We verified the EMP2 gene was knocked out of the cell line (EMP2 CRISPR/Cas9) by using a CRISPR/Cas9 system and found that the expression levels of TRP-2 and TYR were significantly lower in the EMP2 CRISPR/Cas9 cell lines. Loss of EMP2 also reduced migration and invasion of MNT1 melanoma cells. In addition, the melanosome transfer from the melanocytes to keratinocytes in the EMP2 KO cells cocultured with keratinocytes was reduced compared to the cells in the control coculture group. In conclusion, these results suggest that EMP2 is involved in melanogenesis via the regulation of TRP-2 expression.

Primary Cilium by Polyinosinic:Polycytidylic Acid Regulates the Regenerative Migration of Beas-2B Bronchial Epithelial Cells

The airway epithelium is equipped with the ability to resist respiratory disease development and airway damage, including the migration of airway epithelial cells and the activation of TLR3, which recognizes double-stranded (ds) RNA. Primary cilia on airway epithelial cells are involved in the cell cycle and cell differentiation and repair. In this study, we used Beas-2B human bronchial epithelial cells to investigate the effects of the TLR3 agonist polyinosinic:polycytidylic acid [Poly(I:C)] on airway cell migration and primary cilia (PC) formation. PC formation increased in cells incubated under serum deprivation. Migration was faster in Beas-2B cells pretreated with Poly(I:C) than in control cells, as judged by a wound healing assay, single-cell path tracking, and a Transwell migration assay. No changes in cell migration were observed when the cells were incubated in conditioned medium from Poly(I:C)-treated cells. PC formation was enhanced by Poly(I:C) treatment, but was reduced when the cells were exposed to the ciliogenesis inhibitor ciliobrevin A (CilioA). The inhibition of Beas-2B cell migration by CilioA was also assessed and a slight decrease in ciliogenesis was detected in SARS-CoV-2 spike protein (SP)-treated Beas-2B cells overexpressing ACE2 compared to control cells. Cell migration was decreased by SP but restored by Poly(I:C) treatment. Taken together, our results demonstrate that impaired migration by SP-treated cells can be attenuated by Poly(I:C) treatment, thus increasing airway cell migration through the regulation of ciliogenesis.

MiR-144-3p induced by SP1 promotes IL-1β-induced pyroptosis in chondrocytes via PTEN/PINK1/Parkin axis

Rheumatoid arthritis (RA) often leads to functional disabilities and deformities. MiRNA plays a vital role in cell pyroptosis. Nevertheless, the function and underlying mechanism of miR-144-3p in pyroptosis during the progression of RA remains unclear. In this study, N1511 cells were stimulated with IL-1β to construct a RA model. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay was performed to assess the cell viability. Cell pyroptosis was detected by flow cytometry. The levels of inflammatory cytokines (TNF-α, IL-6, and IL-18) were assessed by enzyme-linked immunosorbent assay (ELISA). The relationship among specific protein 1 (SP1), microRNA-144-3p (miR-144-3p), and phosphatase and tensin homolog (PTEN) was explored by dual-luciferase reporter assay, RNA immunoprecipitation (RIP), and chromatin immunoprecipitation (ChIP), respectively. The level of miR-144-3p in N1511 cells was upregulated by IL-1β. MiR-144-3p knockdown inhibited IL-1β-induced pyroptosis in N1511 cells, and the expressions of NOD-like receptor family pyrin domain containing 3 (NLRP3), Cleaved caspase-1, Gasdermin D (GSDMD), and Cleaved caspase-3 in IL-1β-stimulated N1511 cells were increased. The levels of inflammatory cytokines in N1511 cells were increased by IL-1β, which were restored by miR-144-3p knockdown. MiR-144-3p knockdown abolished IL-1β-induced inactivation of putative kinase 1 (PINK1)/Parkin RBR E3 ubiquitin-protein (Parkin) signalling. Moreover, transcription factor SP1 could upregulate miR-144-3p expression and miR-144-3p negatively regulated PTEN expression. In summary, MiR-144-3p induced by SP1 could promote IL-1β-induced chondrocyte pyroptosis via inhibiting PTEN expression and suppressing the activation of PINK1/Parkin signalling, which provided a new strategy against RA.

LW1497, an Inhibitor of Malate Dehydrogenase, Suppresses TGF-β1-Induced Epithelial-Mesenchymal Transition in Lung Cancer Cells by Downregulating Slug

LW1497 suppresses the expression of the hypoxia-inducing factor (HIF)-1α inhibiting malate dehydrogenase. Although hypoxia and HIF-1α are known to be important in cancer, LW1497 has not been therapeutically applied to cancer yet. Thus, we investigated the effect of LW1497 on the epithelial-mesenchymal transition (EMT) of lung cancer cells. A549 and H1299 lung cancer cells were induced to undergo via TGF-β1 treatment, resulting in the downregulation of E-cadherin and upregulation of N-cadherin and Vimentin concurrently with increases in the migration and invasion capacities of the cells. These effects of TGF-β1 were suppressed upon co-treatment of the cells with LW1497. An RNA-seq analysis revealed that LW1497 induced differential expression of genes related to hypoxia, RNA splicing, angiogenesis, cell migration, and metastasis in the A549 lung cancer cell lines. We confirmed the differential expression of Slug, an EMT-related transcription factor. Results from Western blotting and RT-PCR confirmed that LW1497 inhibited the expression of EMT markers and Slug. After orthotopically transplanting A549 cancer cells into mice, LW1497 was administered to examine whether the lung cancer progression was inhibited. We observed that LW1497 reduced the area of cancer. In addition, the results from immunohistochemical analyses showed that LW1497 downregulated EMT markers and Slug. In conclusion, LW1497 suppresses cancer progression through the inhibition of EMT by downregulating Slug.

B Cell Adhesion to Fibroblast-Like Synoviocytes Is Up-Regulated by Tumor Necrosis Factor-Alpha via Expression of Human Vascular Cell Adhesion Molecule-1 Mediated by B Cell-Activating Factor

Fibroblast-like synoviocytes (FLSs) play a key role in the pathogenesis of rheumatoid arthritis (RA) by producing inflammatory cytokines and interacting with various immune cells, which contribute to cartilage destruction. RA-FLSs activated by tumor necrosis factor alpha (TNF-α), exacerbate joint damage by triggering the expression of various inflammatory molecules, including human vascular cell adhesion molecule-1 (hVCAM1) and B cell-activating factor (hBAFF), with a role in maturation and maintenance of B cells. Here, we investigated whether B cell interaction with FLSs could be associated with hVCAM1 expression by TNF-α through hBAFF, using WiL2-NS B cells and MH7A synovial cells. TNF-α enhanced the expression of hVCAM1 and hBAFF. B cell adhesion to FLSs was increased by treatment with TNF-α or hBAFF protein. hVCAM expression was up-regulated by transcriptional activation of the hVCAM1 promoter(−1549 to −54) in MH7A cells treated with hBAFF protein or overexpressed with hBAFF gene. In contrast, hVCAM1 expression was down-regulated by treatment with hBAFF-siRNA. JNK was activated by TNF-α treatment. Then, hVCAM1 expression and B cell adhesion to FLSs were reduced by the treatment with JNK inhibitor SP600125. Transcriptional activity of hVCAM1 by the stimulation with TNF-α was inhibited by the deletion of −1549 to −229 from the hVCAM1 promoter. hVCAM1 expression and B cell adhesion to FLSs were reduced by treatment with hVCAM1-siRNA. Taken together, these results suggest that B cell adhesion to FLSs is associated with TNF-α-induced up-regulation of hVCAM1 expression via hBAFF expression. Thus, the pathological progression of RA may be associated with hVCAM1-mediated interaction of synovial cells with B lymphocytes.

Evaluation of Villus Synovium From Unaffected Metacarpophalangeal Joints of Adult and Juvenile Horses

Horses are a widely accepted model for osteoarthritis (OA) research. Synovial tissue sampling is commonly used in studies to evaluate and grade the progress of OA or to assess treatment effects. Synovial explants play an important role in ex-vivo studies, increasingly replacing the use of living animals. To understand histomorphological changes in the process of joint-related diseases such as OA, detailed information about histomorphometric parameters of unaffected synovial villi is necessary. The objective of the present study was to evaluate the mean width of the intimal synovial lining and its cellularity as well as the vascularization of the subintimal layer in juvenile and adult horses not affected by a joint-related disease. One hundred synovial samples from both metacarpophalangeal joints from 25 horses (one day to 24 years old) were collected to evaluate the following parameters on digitalized hematoxylin-eosin stained samples: Width of intimal synovial lining measured by the distance from the inner joint surface to the subintimal layer; density of the cells making up the intimal synovial lining by counting cell nuclei; vascularization of the subintimal layer measured by the number and size of vessels in relation to the subintimal area. The median width of the intimal lining did not differ among juvenile (22.34 µm) and adult (23.34 µm) horses. The cellularity of the intimal lining was significantly lower in juvenile (one cell/143.8 µm²) than in adult (one cell /188.7µm²), (P < .001) horses as well as the density of blood vessels per mm² within the subintimal layer (juveniles 1/mm² vs. adults 0.05/mm²), (P < .001). This study provides morphometric data regarding synovial intimal width, intimal cellularity, and vascularization of equine synovial villi of unaffected horses. For future studies, age-related characteristics should be taken into consideration when synovial tissue samples are used for in-vivo and in-vitro studies.

Compounds DRG and DAG, Two Phenol Glycosides, Inhibit TNF-α-stimulated Inflammatory Response through Blocking NF-kB/AKT/JNK Signaling Pathways in MH7A Cells

Fourteen constituents were recently isolated from the roots of Dendropanax dentiger with cyclooxygenase-2 (COX-2) inhibitory effects. However, the effect of 14 constituents on rheumatoid arthritis (RA) and their action mechanism remain unclear. The study aimed to explore the anti-RA effect and potential mechanism of these constituents in tumor necrosis factor α (TNF-α)-stimulated human RA fibroblast-like synoviocytes (MH7A cells). The cell viability, nitric oxide (NO) production, inflammatory cytokine levels, and protein expressions were measured by cell counting kit-8 (CCK-8), Griess reagent, ELISA, and Western blot assays, respectively. Results showed that 14 constituents (40 μM) have no cytotoxicity for MH7A cells. Among them, two phenols including 3,4-dimethoxyphenyl-1-O-α-L-rhamnopyranosyl-(1→6)-O-β-D-glucopyranoside (DRG) and 3,4-dimethoxyphenol-β-D-apiofuranosyl-(1→6)-β-D-glucopyranoside (DAG) were shown to significantly inhibit the NO production with IC₅₀ values of 5.25±0.34 and 5.35±0.31 μM, respectively. They also remarkably decreased the release of interleukin (IL)-2, 6, 8, and interferon (IFN)-γ, as well as prominently reduced the phosphorylation protein levels of p65, IkBα, AKT, and JNK at a concentration of 10 μM. Taken together, DRG and DAG could inhibit TNF-α-induced inflammatory response through blocking NF-kB/AKT/JNK signaling pathways in MH7A cells, thus could be promising against RA and other inflammation-related agents.

Anti-inflammatory effect of phenylpropanoids from Dendropanax dentiger in TNF-α-induced MH7A cells via inhibition of NF-κB, Akt and JNK signaling pathways

The root of Dendropanax dentiger (Harms) Merr. has been used for centuries as an empirical treatment for rheumatoid arthritis (RA) in China without scientific validation. In our recent study, nineteen phenylpropanoids (1-19) with cyclooxygenase-2 inhibitory activities from the ethanol extract of D. dentiger roots, indicated to have a potential anti-RA effect. This study, evaluated the anti-RA effect of 19 phenylpropanoids on tumor necrosis factor (TNF)-α induced inflammation in MH7A cells and clarified their underlying mechanisms. As a result, 16 compounds remarkably suppressed nitric oxide (NO) production at a concentration of 40 μM in TNF-α-induced MH7A cells. Among them, pinoresinol (12) and dendrocoumarin A (1) were the most effective substances, which showed significant inhibitory effect on NO production, with IC₅₀ values of 6.25 ± 0.42 and 7.87 ± 0.67 μM, respectively. Furthermore, pinoresinol and dendrocoumarin A remarkably decreased the levels of interleukin (IL)-2, 6, 8, and interferon-gamma (IFN-γ), as well as prominently reduced the phosphorylation protein levels of nuclear factor kappa B (NF-κB) p65, I-kappa-B-alpha (IkBα), protein kinase B (Akt), and c-Jun N-terminal kinase (JNK) by Western blot analysis. Taken together, our findings suggest that pinoresinol and dendrocoumarin A may offer new and safe anti-RA candidates by inhibiting NF-kB, Akt and JNK signaling pathways.