Adjuvant-induced Arthritis In Rats Research Articles

In Silico and In Vivo Evaluation of Anti-Arthritic Effects of Bakuchiol from Psoralea corylifolia Seeds in Experimental Rat Model.

Rheumatoid arthritis is an autoimmune disease mainly affecting the joints categorized by inflammation, swelling of the synovium and decrease in the joint movement. Bakuchiol, a meroterpene class of natural product present in Psoralea corylifolia known to possess anti-inflammatory effects by a variety of mechanisms. However, its effects in rheumatoid arthritis still remain unclear. In the present investigation, we studied the anti-arthritic effects of bakuchiol via in silico and in vivo experiments. It also showed antioxidant effects measured using DPPH assay where it showed free radical scavenging activity with IC50 value 468.26 μg/ml. Molecular Docking studies carried out on COX-1 (PDB ID: 3 N8Z), COX-2 (PDB ID: 4PH9) and TNF-α (PDB ID: 7JRA), proteins involved in inflammation in arthritis. Bakuchiol showed the maximum binding affinity for TNF-α with binding affinity score is -7.29 kcal/moland less affinity was observed for COX-1 and 2. In vivo antiarthritic effects were studied in arthritic female wistar rats model prepared by intradermal injection of freund's complete adjuvant. Bakuchiol was administered orally at dose of 10,20 and 40 mg/kg for 21 days. Our treatment showed that bakuchiol at 20 and 40 mg/kg exhibited significant anti-inflammatory effects (p<0.001) showed by significant decrease in paw volume, paw diameter, spleen and thymus weight and increase in pain threshold and body weight in arthritic rat model. A significant decrease in hematological parameters such as total leukocyte count (TLC), platelet count, CRP and rheumatoid arthritis factor (RF) and increase in red blood cells count, ESR and hemoglobin further demonstrated that bakuchiol treatment suppresses the progression of adjuvant induced arthritis (AIA) in arthritic rat model. Histological analysis further revealed that bakuchiol ameliorates the pathological manifestations of AIA and reverse the abnormality induced by AIA in rats shown by protection against bone necrosis involved with low influx of inflammatory cells. Therefore, in silico and in vivo results revealed that bakuchiol has the potential to be developed as potent antiarthritic agent.

Associations between Gut Microbiota and Microbial Metabolites in Adjuvant- induced Arthritis Rats with Moist Heat Arthralgia Spasm Syndrome.

Rheumatoid Arthritis (RA) is a chronic systemic autoimmune disease. According to Traditional Chinese Medicine (TCM) syndromes theory, moist heat arthralgia spasm syndrome is the most prevalent syndrome of RA patients in the active period. However, the mechanism of alteration of gut microbiota in RA with moist heat arthralgia spasm syndrome has not been reported until now. This study focused on the alteration of gut microbiota in adjuvant-induced arthritis rats with moist heat arthralgia spasm syndrome, elaborated its regulation mechanism, and analyzed the associations between gut microbiota and microbial metabolites. The disease-syndrome combination rat model of RA with moist heat arthralgia spasm syndrome was constructed with Adjuvant-Induced Arthritis (AIA) under damp-heat stimulating. Enzyme-Linked Immunosorbent Assay (ELISA) was used to measure serum biochemical indicators. Damages of ankle joints were observed using hematoxylin and eosin (H&E). 16 small ribosomal subunit RNA (16S rRNA) gene sequencing was conducted to assess the gut microbiota composition and function on feces from rats. Alterations in fecal metabolites profiling were evaluated by fecal metabolomics through Liquid Chromatography-Mass Spectrometry (LC-MS) and Gas Chromatography-Mass Spectrometry (GC-MS). Pearson correlation analysis was performed to explore the associations of altered gut microbiota and microbial metabolites in Model rats. The imbalance of gut microbiota in Model rats was accompanied by metabolic disorders. Lactobacillus, Prevotellaceae_NK3B31_group, Allobaculum, Prevotellaceae_UCG_001, Alloprevotella, and Dubosiella were found to be dominant genera in Model rats. In total, 357 metabolites were significantly altered in Model rats and predominantly enriched into fatty acid degradation and glycerophospholipid metabolism. Pearson correlation analysis showed that TNF-α and IL-1β were associated with Prevotellaceae_Ga6A1_group and 3R-hydroxy-docosan-5S-olide, alpha-N-(3-hydroxy-14-methyl-pentadecanoyl)-ornithine, 17-methyl-trans-4,5- methylenenona-decanoic acid, Semiplenamide F. The key differential microbiota genera and differential microbial metabolites may become important targets for the treatment of RA and provide the theoretical basis for exploring the pathogenesis of RA.

Therapeutic potential of d-limonene in rheumatoid arthritis: Modulation of inflammatory, anti-inflammatory cytokines, and prostaglandin E2.

Rheumatoid arthritis (RA) is a persistent autoimmune disorder predominantly affecting the joint structures, eliciting inflammatory responses, and ultimately leading to degenerative changes without proper medical intervention. Ultimately, this can severely impair joint function and impact the patient's quality of life. Current treatment approaches include disease-modifying anti-rheumatic drugs, non-steroidal anti-inflammatory drug, corticosteroids, and biologic therapies for RA management. The current study contributes to the ongoing advancements in RA treatment. d-Limonene is a monocyclic monoterpene. It is present in essential oils of various aromatic plants, such as Lippia alba and Artemisia dracunculus, and in citrus fruits such as lemon and orange. It has reported anti-inflammatory and anti-nociceptive properties and was selected for the current study as a potential anti-arthritic candidate. It was administered at three dosages (25, 50, 100 mg/kg, b.w., p.o) in Complete Freund's adjuvant-induced arthritic rats over 28 days. The efficacy of the compound was compared to piroxicam, a widely used standard drug for treating RA. The anti-arthritic activity of the compound was assessed by measuring arthritic scoring and plethysmometry at both baseline and post-intervention stages. Additional confirmation of the investigation was sought by performing biochemical and hematological activities. Moreover, quantitative polymerase chain reaction was employed to determine the levels of messenger RNA expression for transcription factors such as tumor necrosis factor-α, interleukin (IL)-1β, nuclear factor-κB, matrix metalloproteinase-3, IL-6, and IL-4 in the blood. The levels of PGE2 were evaluated by enzyme-linked immunosorbent assay. The histopathological and radiographic studies were also carried out for further confirmation. The results of these findings supported our assertion regarding the anti-arthritic potential of the compound.

Hyaluronic acid dissolving microneedle patch-assisted acupoint transdermal delivery of triptolide for effective rheumatoid arthritis treatment

Triptolide (TP), a major active component of the herb Tripterygium wilfordii Hook F, has been shown excellent pharmacological effects on rheumatoid arthritis. However, TP is prone to causing severe organ toxicity, which limits its clinical application. In recent years, microneedle technology has provided a new option for the treatment of arthritis due to its advantages of efficient local transdermal drug delivery. In this study, we constructed a microneedle platform to deliver TP locally to the joints, thereby enhancing TP penetration and reducing systemic toxicity. Additionally, we investigated whether acupoint drug delivery can produce a synergistic effect of needles and drugs. First, TP was loaded into microneedles using polyvinylpyrrolidone and hyaluronic acid as matrix materials. Next, we established a rat adjuvant-induced arthritis (AIA) model to evaluate the therapeutic effect of TP-loaded microneedles. The experiments showed that TP-loaded microneedles alleviated the AIA rats’ inflammatory response, joint swelling, and bone erosion. However, there was no significant difference in the therapeutic effect observed in the acupoint and non-acupoint administration groups. In conclusion, TP-loaded microneedles have the advantages of safety, convenience, and high efficacy over conventional administration routes, laying a foundation for the transdermal drug delivery system-based treatment of rheumatoid arthritis.

Anti-arthritic activity of Trayodashang guggulu, a classical Ayurvedic formulation against complete Freund’s adjuvant-induced rheumatoid arthritis in rats

BackgroundRheumatoid arthritis is a chronic autoimmune disease affecting millions of people across the world. Trayodashang guggulu (TG) is a classical Ayurvedic formulation used for the treating joint diseases since decades in the Indian system of traditional medicine. The aim of the study was to evaluate anti-arthritic activity of TG against complete Freund’s adjuvant-induced arthritis in Wistar rats.MethodsArthritis was induced by single injection of 0.1 ml complete Freund’s adjuvant into the intraplanter surface of left hind paw of Wistar rats. TG was administered orally at the doses of 100, 200, 400 and 800 mg/kg body weight for 14 days. In the preventive dose group, TG was administered at the dose of 100 mg/kg body weight, orally for 28 days. Paw swelling, joint circumference, serum rheumatoid factor, C-reactive protein, serum IL-1β, TNF-α and histopathological parameters were assessed for the evaluation of arthritis. Effects of TG were compared with standard allopathic drug ibuprofen.ResultsTG reversed complete Freund’s adjuvant-induced arthritis in rats when used for 14 and 28 days. Serum rheumatoid factor, C-reactive protein, IL-1β and TNF-α were decreased in rats treated with both standard drug ibuprofen and TG.ConclusionOral administration of TG reduced experimentally induced rheumatoid arthritis in rats by reversing elevated level of serum biochemical markers as well as reducing joint destruction similar to ibuprofen. Results obtained from the study paved the way in exploring more specific mechanisms of action of TG involving in vitro and in silico models.

Tetraspanin32 (TSPAN32) is downregulated in rheumatoid arthritis: Evidence from animal models and patients.

This study aimed to investigate the role of TSPAN32, a member of the tetraspanin family, in rheumatoid arthritis (RA). The objective was to assess the expression levels of TSPAN32 in experimental RA models and in RA patient immune cells, exploring its potential as a regulatory factor in RA pathogenesis. The study employed adjuvant-induced arthritis in rats and collagen-induced arthritis (CIA) in mice as experimental models. Exvivo analyses included evaluating TSPAN32 expression in immune cells at different stages of the disease. In silico data analysis involved examining transcriptomic datasets from drug-naïve and treated RA patients to correlate TSPAN32 expression with clinical parameters. TSPAN32 overexpression experiments in splenocytes from CIA mice aimed to demonstrate its functional impact on antigen-specific immune responses. The animal models revealed a significant downregulation of TSPAN32, particularly in synovial-infiltrating T cells. Also, TSPAN32 overexpression inhibited pro-inflammatory cytokine production in splenocytes. In RA patients, TSPAN32 was consistently downregulated in circulating and synovial-infiltrating T cells, as well as in CD8+ T cells, B cells and NK cells. Drug treatment did not significantly alter TSPAN32 levels. Negative correlations were observed between TSPAN32 expression and inflammatory markers (CRP, ESR) and clinical scores (SDAI) in RA patients. This study suggests that reduced TSPAN32 expression characterizes pathogenic T-cell populations in RA, highlighting its potential as biomarker for inflammation and disease activity. TSPAN32 may play a crucial role in shaping adaptive immune responses in RA, opening avenues for novel therapeutic strategies targeting this tetraspanin family member.

Regulating the lncRNA DSCR9/RPLP2/PI3K/AKT axis: an important mechanism of Xinfeng capsules in improving rheumatoid arthritis.

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic and symmetrical polyarthritis. RA patients often experience inflammatory reaction and hypercoagulable state, which together affect the self-perception of patient (SPP). Currently, inhibiting inflammation and hypercoagulable state are common treatment methods for alleviating RA symptoms. Xinfeng Capsules (XFC) has a long history of treating RA, and can effectively improve the inflammatory response and hypercoagulable state of RA. However, the potential mechanisms have not yet been determined. This study elucidated the action mechanism of XFC in RA inflammation and hypercoagulability through the lncDSCR9/RPLP2/PI3K/AKT axis. Clinical observations indicated that there was a strong link between XFC therapy and improvements in inflammatory and coagulation biomarkers, as well as SPP among RA patients. The subsequent network pharmacology analysis results identified the PI3K/AKT signaling pathway as a potential mediator for XFC treatment of RA. Furthermore, clinical validation and sequencing results revealed that lncRNA DSCR9 expression (a gene implicated in inflammation and coagulation) was negatively correlated with clinical markers of inflammation and coagulation, while positively correlated with SF-36 indicators. Notably, XFC treatment remarkably upregulated lncRNA DSCR9 expression and downregulated PI3K and AKT expressions, showing opposite expression trends to the untreated cases.The regulatory effect of XFC on the lncRNA DSCR9/RPLP2/PI3K/AKT axis in RA was investigated using techniques such as RNA pull-down assay, Western blot analysis, RT-PCR, and EdU assay. Moreover, the administration of the PI3K/AKT agonist RMH can counteract the effects of XFC on p-PI3K, p-AKT, inflammation, and hypercoagulability, reinforcing the role of pathway. Finally, animal studies utilizing HE staining and transmission electron microscopy (TEM) demonstrated that XFC notably decreased PI3K and AKT expressions in adjuvant-induced arthritis (AA) rats, mitigated inflammation and hypercoagulability, and enhanced the ultrastructure of synovial cells. These findings underscored the potential mechanisms of XFC in the treatment of RA. Regulating the lncRNA DSCR9/RPLP2/PI3K/AKT axis may be an important mechanism by which XFC improved RA inflammatory response and hypercoagulable state.

Qing-Luo-Yin Eased Adjuvant-Induced Arthritis by Inhibiting SIRT1-Controlled Visfatin Production in White Adipose Tissues.

Nicotinamide adenine dinucleotide (NAD)-dependent deacetylase SIRT1 regulates both metabolism and immune functions. This study investigated if SIRT1 inhibitory property of herbal formula Qing-Luo-Yin (QLY) contributed to its anti-rheumatic effects. Adjuvant-induced arthritis (AIA) rats were treated by QLY and nicotinamide mononucleotide (NMN, a biosynthesis precursor of NAD) for 38 days. After sacrifice, blood, paws, liver and white adipose tissues (WAT) were collected. Pre-adipocytes were cultured by the rats' serum. The medium was used for monocytes culture. Some pre-adipocytes were treated by QLY-derived SIRT1 inhibitors. SIRT1 was silenced or overexpressed beforehand. The samples were subjected to kits-based quantification, polymerase-chain reaction, western-blot, immunofluorescence, and histology experiments. AIA rats experienced significant fat loss in liver and WAT. Expression of many SIRT1-related signals like PPARγ, PGC-1α, HSL, ATGL and CPT-1A were altered. QLY attenuated all these abnormalities and joint injuries. By pan-acetylation up-regulation, visfatin was obviously reduced in QLY-treated AIA rats' blood (from 191.8 to 127.0 pg/mL). NMN sustained SIRT1 activation by replenishing NAD, and weakened these effects. QLY-containing serum and the related compounds showed similar impacts on pre-adipocytes, resembling the changes in QLY-treated AIA rats' WAT. These treatments suppressed AIA serum-induced visfatin secretion (from 49.3 to 36.1 and 30.7 pg/mL). This effect was impaired by SIRT1 overexpression. The medium from the compounds-treated pre-adipocytes impaired NF-κB activation in AIA serum-cultured monocytes. Besides fat depletion, SIRT1 up-regulation in rheumatic subjects' WAT promotes visfatin production, and exacerbates inflammation. SIRT1 inhibition in WAT is an anti-rheumatic way of QLY independent of immune regulation.

Gingerol nanoparticles attenuate complete Freund adjuvant-induced arthritis in rats via targeting the RANKL/OPG signaling pathway.

Rheumatoid arthritis (RA) is characterized by inflammatory joint pathology leading to the degradation of articular bone and cartilage, primarily triggered by synovial inflammation, resulting in joint discomfort. The metacarpophalangeal and proximal interphalangeal joints are predominantly affected. Treatment typically involves a combination of biological and synthetic disease-modifying antirheumatic drugs (DAMARDs) alongside steroid therapy. The application of nanomedicine has been instrumental in enhancing treatment efficacy by facilitating controlled release of pharmacologically active compounds, thus augmenting bioavailability and enabling targeted drug delivery. Gingerol, a constituent of ginger, possesses multifaceted properties. including anti-inflammatory, anti-oxidant, antidiabetic, and antipyretic effects. In this study, gingerol-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs), coated with chitosan, were administered orally to rats over a period of 21days to address RA induced by complete Freund adjuvant (CFA). The rats were segregated into four experimental groups. Upon completion of the treatment regimen, blood samples were collected for the assessment of cyclooxygenase-2 (COX-2), RA factor, interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α). Subsequent gene expression analysis was conducted to evaluate the levels of interleukin-4 (IL-4), interleukin-17a (IL-17a), IL-6, interferon-gamma (INF-γ), TNF-α, interleukin-1 beta (IL-1β), osteoprotegerin (OPG), and receptor activator of nuclear factor kappa-B ligand (RANKL). Statistical analyses utilizing one-way ANOVA followed by Tukey tests were applied to the data. The gene expression profiling revealed significant disparities in mRNA levels of IL-1β, IL-6, IL-4, IL-17a, RANKL, INF-γ, and TNF-α between the CFA-induced arthritis group and the control group. Consequently, it was inferred that gingerol-loaded PLGA NPs coated with chitosan exhibited heightened therapeutic efficacy in addressing CFA-induced arthritis in rats.

Nuciferine inhibits TLR4/NF-κB/MAPK signaling axis and alleviates adjuvant-induced arthritis in rats

Rheumatoid arthritis is an inflammatory condition primarily affecting the joints. Nuciferine (NCF), a key bioactive aporphine alkaloid biosynthesized in lotus leaves, exhibits promising anti-inflammatory and antioxidant properties. In this study, we investigated whether NCF could alleviate inflammatory arthritis conditions in a complete Freund's adjuvant (CFA)-mediated arthritis model in rats. The arthritis model was established through intradermal injection of CFA (100 μL) in the sub-plantar region of the right hind paw. The arthritic animals were treated orally with NCF at 5 and 10 mg/kg and indomethacin (Indo) at 5 mg/kg body weight as reference control. NCF treatment remarkably alleviated inflammatory joint swelling and arthritic index. The radiological and histological analysis revealed evidence of the beneficial effects of NCF. NCF treatment decreased the content of pro-inflammatory cytokines (TNF-α and IL-1β) and myeloperoxidase (MPO) activity and restored the anti-inflammatory cytokine (IL-10) in the paw joints. The serum levels of pro-inflammatory cytokines were also markedly reduced in the NCF (10 mg/kg) treatment group. Moreover, the arthritis-induced inflammatory mediators, including cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) and the toll-like receptor (TLR)-4, mitogen-activated protein kinase (MAPK), and nuclear factor-κB (NF-κB) signaling proteins were substantially decreased in the NCF treatment groups. NCF treatment also restored the antioxidant defense enzymes and abrogated lipid peroxidation in the paw tissue. Our findings strongly suggest that NCF is a promising therapeutic molecule for rheumatoid arthritis, inspiring further research, and development in this area.

Evaluation of Anti-arthritic Activity of hydro-alcoholic Root Extract of Moringa concanensis in complete Freund’s Adjuvant-induced Arthritic Rats

Background: Arthritis, a debilitating inflammatory disorder, has been a target for numerous therapeutic interventions. Natural plant extracts, especially those rich in phytochemicals like terpenoids, have demonstrated potential as alternative remedies. In this context, Moringa concanensis, a traditionally known medicinal plant, needs further elucidation regarding its anti-arthritic efficacy. Objective: This study aimed to investigate the anti-arthritic potential of the hydro-alcoholic root extract of Moringa concanensis in a Complete Freund’s Adjuvant (CFA)-induced arthritis rat model. Methods: An initial phytochemical screening and GC-MS analysis were executed on the hydro-alcoholic root extract of Moringa concanensis. Arthritis was subsequently induced in rats using CFA. Comprehensive assessments were made on various parameters such as body weight, paw volume, joint diameter, serum rheumatoid factor, serum C-reactive protein, ALP, ALT, total protein, total cholesterol, and urea. Additionally, histopathological studies of the liver and ankle joints were carried out. For comparative efficacy, methotrexate was employed as a positive control. Results: Rats receiving the hydro-alcoholic extract at dosages of 200mg/kg (p.o) and 400mg/kg (p.o) exhibited a notable reduction in the physical and biochemical indicators of arthritis, in comparison to the untreated arthritic model. Histopathological observations further confirmed that the anti-arthritic effects of the hydro-alcoholic extract were on par with methotrexate. Conclusion: The hydro-alcoholic root extract of Moringa concanensis exhibited significant anti-arthritic activity, possibly attributed to its terpenoid content. The findings advocate for its potential application as a therapeutic agent in managing arthritis.

Discovery of CYP2E1 as a novel target in rheumatoid arthritis and validation by a new specific CYP2E1 inhibitor

Considerable evidence indicates that CYP2E1 is associated with a variety of inflammatory diseases. Here we evaluated CYP2E1 as a potential therapeutic target for rheumatoid arthritis (RA) and established the protective effect of a new CYP2E1 inhibitor. Gene-expression datasets were used to analyze the change in expression of CYP2E1 in RA patients; CYP2E1 activity in collagen-induced arthritis (CIA) rats was determined by HPLC. We further evaluated the protective effects of Cyp2e1 knockout and a CYP2E1-specific inhibitor, Q11, synthesized by our group, in CIA and adjuvant-induced arthritis (AIA) rats. The expression of CYP2E1 in synovial tissue was elevated in RA patients and in CIA rats and the activity of CYP2E1 in vivo and in vitro in CIA rats was greater than that of controls. Cyp2e1 knockout significantly reduced the incidence of CIA and alleviated the severity of symptoms. Treatment with different doses of Q11 decreased paw thickness, volume and arthritis scores and reduced the serum levels of IL‐6, TNF‐α, IL‐1β and MDA, and increased the level of GSH in CIA rats. A similar inhibitory effect was exhibited for Q11 in the AIA rats. Moreover, Q11 significantly impeded proliferation, migration, and invasion of human rheumatoid arthritis synovial fibroblasts cells. Q11 decreased the release of ROS and enhanced Nrf2 nuclear translocation and HO-1 expression in the cell nucleus. Overall, our results indicated that CYP2E1 may be a new target for RA and Q11 has potential protective effects against RA by reducing oxidative stress and opposing the inflammatory response via the ROS/Nrf2/HO-1 signaling pathway.

Targeting next-generation PDE4 inhibitors in search of potential management of rheumatoid arthritis and psoriasis

Immune-mediated inflammatory diseases (IMIDs) comprise a broad spectrum of conditions characterized by systemic inflammation affecting various organs and tissues, for which there is no known cure. The isoform-specific inhibition of phosphodiesterase-4B (PDE4B) over PDE4D constitutes an effective therapeutic strategy for the treatment of IMIDs that minimizes the adverse effects associated with non-selective PDE4 inhibitors. Thus, we report a new class of isoquinolone derivatives as next-generation PDE4 inhibitors for effective management of rheumatoid arthritis (RA) and psoriasis. Among the series, 8 compounds i.e. 1e, 1l, 1m, 1n, 1o, 2m, 2o and 3o showed promising PDE4B inhibition (>80 %) in vitro with IC50 ∼ 1.4–6.2 µM. The compound 1l was identified as an initial hit and was pursued for further studies. According to structure–activity relationship (SAR), an allyl group at C-4 position improved PDE4B inhibition. The correlation between in vitro activity data and binding affinities obtained via molecular docking suggested that the high-affinity binding to PDE4B is a prerequisite for the effective inhibition of PDE4B. Notably, the hit 1l showed selectivity towards PDE4B over PDE4D in vitro. Furthermore, 1l treatment (30 mg/kg) in the adjuvant-induced arthritis (AIA) rat model induced by complete Freund’s adjuvant (CFA) demonstrated anti-arthritic potential via ameliorating paw swelling and body weight, narrowing joint space, reducing excessive immune cells infiltration and pannus formation in addition to reducing mRNA expression of pro-inflammatory cytokines such as TNF-α and IL-6 in synovial tissues of experimental rats. Additionally, 1l reduced the hyper-proliferative state and colony forming potential of IMQ-induced psoriatic keratinocytes. The treatment of these cells with 1l markedly reduced the protein levels of Ki67 and mRNA levels of pro-inflammatory cytokines e.g. IL-17A and TNF-α suggesting its potent anti-psoriatic potential. Furthermore, 1l did not show any significant adverse effects when evaluated in a systematic toxicity (e.g. teratogenicity, hepatotoxicity and cardiotoxicity) studies in zebrafish at the tested concentrations (1–100 µM) and the NOAEL (no-observed-adverse-effect level) was found to be 100 µM. Thus, with promising anti-inflammatory effects both in vitro and in vivo along with PDE4B selectivity with an acceptable safety margin, 1l emerged as a new and promising inhibitor for further studies.

The Combined Effect of Curcumin and Crocin on the Reduction of Inflammatory Responses in Arthritic Rats.

The present study evaluated the anti-arthritic impact of combined crocin and curcumin on Adjuvant Induced Arthritis (AIA) in rats. The arthritis model was induced in rats by injecting Complete Freund's adjuvant (CFA) into the right hind paw and was subsequently treated with crocin and curcumin. Evaluation of anti- arthritic activity was carried out using paw swelling, hematological parameters, biochemical parameters, inflammatory cytokines, and histopathology of rats. The results showed increased paw swelling, increased serum markers levels, including CRP, RF, ALP, ALT, and AST, and inflammatory cytokines (ILlβ and TNFα) along with histology changes (cartilage and bone degradation) in arthritic rats when compared to the normal group. Crocin, curcumin and crocin + curcumin administration at different doses (especially combination at 40 mg/kg and 30 mg/kg, respectively), as well as MTX, revealed a suitable therapeutic effect on AIA rats. Moreover, both phytochemicals and their combination at different doses showed effective anti- arthritic effects owing to their anti-inflammatory effects. Crocin and curcumin, either alone or in combination, can be a suitable treatment modality for rheumatoid arthritis.

Dexamethasone Palmitate Encapsulated in Palmitic Acid Modified Human Serum Albumin Nanoparticles for the Treatment of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory joint condition characterized by symmetric, erosive synovitis leading to cartilage erosion and significant disability. Macrophages, pivotal in disease progression, release pro-inflammatory factors upon activation. We developed a nanoparticle delivery system (DXP-PSA NPs), based on palmitic acid modified human serum albumin (PSA), to deliver dexamethasone palmitate (DXP) directly to sites of inflammation, enhancing treatment effectiveness and minimizing possible side effects. The system actively targets scavenger receptor-A on activated macrophages, achieving selective accumulation at inflamed joints. In vitro effect and preliminary targeting abilities were investigated on LPS-activated RAW264.7 cells. The in vivo efficacy and safety were evaluated and compared side to side with commercially available lipid emulsion Limethason® in an advanced adjuvant-induced arthritis rat model. DXP-PSA NPs offer a novel approach to RA treatment and presents promising prospects for clinical translation.

Responsive Multi-Arm PEG-Modified COF Nanocomposites: Dynamic Photothermal, pH/ROS Dual-Responsive, Targeted Carriers for Rheumatoid Arthritis Treatment.

Rheumatoid arthritis (RA) is a chronic immune disease characterized by the infiltration of immune cells and the proliferation of fibroblast-like synoviocytes (FLS) at the joint site, leading to inflammation and joint destruction. However, the available treatment options targeting both inflammatory and proliferative FLS are limited. Herein, we present three covalent organic frameworks (COFs) photothermal composite systems modified with multi-armed PEG for the treatment of RA. These systems exhibited a dual response under low pH and high reactive oxygen species (ROS) conditions at the site of inflammation, with a specific focus on delivering the protein drug ribonuclease A (RNase A). This protein, in combination with photothermal therapy, effectively targeted and eliminated FLS while reducing ROS production by immune cells. Notably, molecular docking studies revealed the interaction between RNase A and NF-κB p65 protein, and Western blotting confirmed its inhibitory effect on NF-κB activity. In vitro and in vivo experiments verified the significant reduction in joint swelling and deformities in adjuvant-induced arthritis (AIA) rats after treatment with RNase A delivered by multi-armed PEG-modified COF ligands, restoring joint morphology to normal. In vivo plasma indices demonstrated the ability of this treatment to scavenge and reduce pro-inflammatory cytokines while maintaining a favorable biosafety profile. These findings underscore the promising therapeutic potential of COFs for the treatment of RA, highlighting their unique capabilities in addressing both inflammatory and proliferative aspects of the disease and expanding the scope of biomedical applications for COFs. This article is protected by copyright. All rights reserved.

Discovery and Development of NLRP3 Inhibitors Targeting the LRR Domain to Disrupt NLRP3-NEK7 Interaction for the Treatment of Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a chronic autoimmune disease. Targeting NLRP3 inflammasome, specifically its interaction with NEK7 via the LRR domain of NLRP3, is a promising therapeutic strategy. Our research aimed to disrupt this interaction by focusing on the LRR domain. Through virtual screening, we identified five compounds with potent anti-inflammatory effects and ideal LRR binding affinity. Lead compound C878-1943 underwent structural optimization, yielding pyridoimidazole derivatives with different anti-inflammatory activities. Compound I-19 from the initial series effectively inhibited caspase-1 and IL-1β release in an adjuvant-induced arthritis (AIA) rat model, significantly reducing joint swelling and spleen/thymus indices. To further enhance potency and extend in vivo half-life, a second series including II-8 was developed, demonstrating superior efficacy and longer half-life. Both I-19 and II-8 bind to the LRR domain, inhibiting NLRP3 inflammasome activation. These findings introduce novel small molecule inhibitors targeting the LRR domain of NLRP3 protein and disrupt NLRP3-NEK7 interaction, offering a novel approach for RA treatment.

Nerve Growth Factor Signaling Modulates the Expression of Glutaminase in Dorsal Root Ganglion Neurons during Peripheral Inflammation.

Glutamate functions as the major excitatory neurotransmitter for primary sensory neurons and has a crucial role in sensitizing peripheral nociceptor terminals producing sensitization. Glutaminase (GLS) is the synthetic enzyme that converts glutamine to glutamate. GLS-immunoreactivity (-ir) and enzyme activity are elevated in dorsal root ganglion (DRG) neuronal cell bodies during chronic peripheral inflammation, but the mechanism for this GLS elevation is yet to be fully characterized. It has been well established that, after nerve growth factor (NGF) binds to its high-affinity receptor tropomyosin receptor kinase A (TrkA), a retrograde signaling endosome is formed. This endosome contains the late endosomal marker Rab7GTPase and is retrogradely transported via axons to the cell soma located in the DRG. This complex is responsible for regulating the transcription of several critical nociceptive genes. Here, we show that this retrograde NGF signaling mediates the expression of GLS in DRG neurons during the process of peripheral inflammation. We disrupted the normal NGF/TrkA signaling in adjuvant-induced arthritic (AIA) Sprague Dawley rats by the pharmacological inhibition of TrkA or blockade of Rab7GTPase, which significantly attenuated the expression of GLS in DRG cell bodies. The results indicate that NGF/TrkA signaling is crucial for the production of glutamate and has a vital role in the development of neurogenic inflammation. In addition, our pain behavioral data suggest that Rab7GTPase can be a potential target for attenuating peripheral inflammatory pain.

Manual acupuncture ameliorates inflammatory pain by upregulating adenosine A3 receptor in complete Freund’s adjuvant-induced arthritis rats

BackgroundAdenosine A3 receptor (A3R) exerts analgesic, anti-inflammatory, and anti-nociceptive effects. In this study, we determined the analgesic mechanism of manual acupuncture (MA) in rats with complete Freund's adjuvant (CFA)-induced arthritis and explored whether MA ameliorates inflammation in these rats by upregulating A3R. MethodsSixty Sprague Dawley (SD) rats were randomly divided into the following groups: Control, CFA, CFA + MA, CFA + sham MA, CFA + MA + DMSO, CFA + MA + IB-MECA, and CFA + MA + Reversine groups. The arthritis rat model was induced by injecting CFA into the left ankle joints. Thereafter, the rats were subjected to MA (ST36 acupoint) for 3 days. The clinical indicators paw withdrawal latency (PWL), paw withdrawal threshold (PWT), and open field test (OFT) were used to determine the analgesic effect of MA. In addition, to explore the effect of A3R on inflammation after subjecting arthritis rats to MA, IB-MECA (A3R agonist) and Reversine (A3R antagonist) were injected into ST36 before MA. ResultsMA ameliorated the pathological symptoms of CFA-induced arthritis, including the pain indicators PWL and PWT, number of rearing, total ambulatory distance, and activity trajectory. Furthermore, after MA, the mRNA and protein expression of A3R was upregulated in CFA-induced arthritis rats. In contrast, the protein levels of TNF-α, IL-1β, Rap1, and p-p65 were downregulated after MA. Interestingly, the A3R agonist and antagonist further downregulated and upregulated inflammatory cytokine expression, respectively, after MA. Furthermore, the A3R antagonist increased the degree of ankle swelling after MA. ConclusionMA can alleviate inflammatory pain by inhibiting the NF-κB signaling pathway via upregulating A3R expression of the superficial fascia of the ST36 acupoint site in CFA-induced arthritis rats.

Acupuncture alleviates inflammatory pain by activating CXCL1/CXCR2 signaling in the primary somatosensory cortex in adjuvant induced arthritis rats.

To observe whether acupuncture up-regulates chemokine CXC ligand 1 (CXCL1) in the brain to play an analgesic role through CXCL1/chemokine CXC receptor 2 (CXCR2) signaling in adjuvant induced arthritis (AIA) rats, so as to reveal its neuro-immunological mechanism underlying improvement of AIA. BALB/c mice with relatively stable thermal pain reaction were subjected to planta injection of complete Freund adjuvant (CFA) for establishing AIA model, followed by dividing the AIA mice into simple AF750 (fluorochrome) and AF750+CXCL1 groups (n=2 in each group). AF750 labeled CXCL1 recombinant protein was then injected into the mouse's tail vein to induce elevation of CXCL1 level in blood for simulating the effect of acupuncture stimulation which has been demonstrated by our past study. In vivo small animal imaging technology was used to observe the AF750 and AF750+CXCL1-labelled target regions. After thermal pain screening, the Wistar rats with stable pain reaction were subjected to AIA modeling by injecting CFA into the rat's right planta, then were randomized into model and manual acupuncture groups (n=12 in each group). Other 12 rats that received planta injection of saline were used as the control group. Manual acupuncture (uniform reinforcing and reducing manipulations) was applied to bilateral "Zusanli" (ST36) for 4×2 min, with an interval of 5 min between every 2 min, once daily for 7 days. The thermal pain threshold was assessed by detecting the paw withdrawal latency (PWL) using a thermal pain detector. The contents of CXCL1 in the primary somatosensory cortex (S1), medial prefrontal cortex, nucleus accumbens, amygdala, periaqueductal gray and rostroventromedial medulla regions were assayed by using ELISA, and the expression levels of CXCL1, CXCR2 and mu-opioid receptor (MOR) mRNA in the S1 region were detected using real time-quantitative polymerase chain reaction. The immune-fluorescence positive cellular rate of CXCL1 and CXCR2 in S1 region was observed after immunofluorescence stain. The immunofluorescence double-stain of CXCR2 and astrocyte marker glial fibrillary acidic protein (GFAP) or neuron marker NeuN or MOR was used to determine whether there is a co-expression between them. In AIA mice, results of in vivo experiments showed no obvious enrichment signal of AF750 or AF750+CXCL1 in any organ of the body, while in vitro experiments showed that there was a stronger fluorescence signal of CXCL1 recombinant protein in the brain. In rats, compared with the control group, the PWL from day 0 to day 7 was significantly decreased (P<0.01) and the expression of CXCR2 mRNA in the S1 region significantly increased in the model group (P<0.05), while in comparison with the model group, the PWL from day 2 to day 7, CXCL1 content, CXCR2 mRNA expression and CXCR2 content, and MOR mRNA expression in the S1 region were significantly increased in the manual acupuncture group (P<0.05, P<0.01). Immunofluorescence stain showed that CXCR2 co-stained with NeuN and MOR in the S1 region, indicating that CXCR2 exists in neurons and MOR-positive neurons but not in GFAP positive astrocytes. Acupuncture can increase the content of CXCL1 in S1 region, up-regulate CXCR2 on neurons in the S1 region and improve MOR expression in S1 region of AIA rats, which may contribute to its effect in alleviating inflammatory pain.