Applicability and implementation of the collagen-induced arthritis mouse model, including protocols (Review)

A Caspase-3 responsive nanoemulsion for targeted treatment of rheumatoid arthritis through dual modulation of inflammation and mitochondrial dysfunction

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by joint inflammation, pain, and progressive joint damage. Current treatments, while effective, are limited by their potential side effects, particularly in long-term use. This study introduces a novel nanoemulsion-based therapeutic approach combining rapamycin, an mTOR inhibitor, with SS31, a mitochondrial-targeting antioxidant peptide. The rapamycin-SS31 conjugate (RS31) is encapsulated within a nanoemulsion (RS31@NEs) designed to selectively release its components in response to elevated Caspase-3 levels, prevalent in inflamed joints. In vitro and in vivo studies using zymosan-induced arthritis (ZIA) and collagen-induced arthritis (CIA) mouse models demonstrated that RS31@NEs effectively reduced pro-inflammatory cytokines, mitigated oxidative stress, and improved immune modulation by enhancing regulatory T and B cell functions. These findings highlight RS31@NEs as a promising dual-action therapy for RA, combining anti-inflammatory and mitochondrial protective effects while minimizing systemic toxicity.

Role of activating transcription factor 3 as a mediator of the protective effects of berberine against lipopolysaccharide-stimulated SW982 cells and in rheumatoid arthritis animal models

This study aimed to explore the protective effects of berberine against rheumatoid arthritis (RA) and clarify the role of activating transcription factor 3 (ATF3) in the mechanism of action of berberine, using a lipopolysaccharide (LPS)-stimulated SW982 human synovial cell line. Berberine treatment resulted in a concentration-dependent reduction in LPS-induced proinflammatory cytokines and matrix metalloproteinases (MMPs) in SW982 cells. These inhibitory effects were associated with increased ATF3 expression, reduced nuclear translocation of nuclear factor-κB (NF-κB), and diminished phosphorylation of mitogen-activated protein kinase (MAPK). In contrast, ATF3 knockdown reversed the suppressive effects of berberine on proinflammatory cytokines and MMP production, leading to enhanced MAPK phosphorylation; however, it had minimal impact on adenosine monophosphate-activated protein kinase (AMPK) phosphorylation. Furthermore, AMPK knockdown negated the protective effects of berberine and reduced ATF3 levels, whereas treatment with 5-aminoimidazole-4-carboxamide ribonucleotide, an AMPK activator, replicated the beneficial effects of berberine. In an in vivo collagen-induced arthritis (CIA) mouse model, intraperitoneal administration of berberine significantly reduced paw edema and arthritis severity, accompanied by ATF3 induction and increased AMPK phosphorylation in the synovial tissue. These findings highlighted the pivotal role of ATF3 in mediating the protective effects of berberine in RA- and LPS-activated synoviocytes, suggesting its potential as a therapeutic agent for RA management.

Pharmacological modes of plant-derived compounds for targeting inflammation in rheumatoid arthritis: A comprehensive review on immunomodulatory perspective

BACKGROUND

Rheumatoid arthritis (RA) is one of the most prevalent autoimmune, chronic, inflammatory disease characterized by joint inflammation, synovial swelling, loss of articular structures, swelling, and pain. RA is a major cause of discomfort and disability worldwide, associated with infectious agents, genetic determinants, epigenetic factors, advancing age, obesity, and smoking. Although conventional therapies for RA alleviate the symptoms, but their long-term use is associated with significant side effects. This necessitates the urge to discover complementary and alternative medicine from natural products with minimum side effects.

PURPOSE

In this review, natural product's potential mechanism of action against RA has been documented in the setting of in-vivo, in-vitro and pre-clinical trials, which provides new treatment opportunities for RA patients. The bioefficacy of these natural product's bioactive compounds must be further studied to discover novel natural medications for RA with high selectivity, improved effectiveness, and economic replacement with minimum side effects.

STUDY DESIGN AND METHODS

The current review article was designed systematically in chronological order. Plants and their phytochemicals are discussed in an order concerning their mode of action. All the mechanisms of action are depicted in diagrams which are thoroughly generated by the Chembiodraw to maintain the integrity of the work. Moreover, by incorporating the recent data with simple language which is not incorporated previously, we tried to provide a molecular insight to the readers of every level and ethnicity. Moreover, Google Scholar, PubMed, ResearchGate, and Science Direct databases were used to collect the data.

SOLUTION

Traditionally, various plant extracts and bioactive compounds are effectively used against RA, but their comprehensive pharmacological mechanistic actions are rarely discussed. Therefore, the objective of this study is to systematically review the efficacy and proposed mechanisms of action of different plants and their bioactive compounds including Tripterygium wilfordii Hook F (celastrol and triptolide), Nigella sativa (thymoquinone), Zingiber officinale (shogaols, zingerone), Boswellia serrata (boswellic acids), Curcuma longa (curcumin), and Syzygium aromaticum (eugenol) against rheumatoid arthritis.

CONCLUSION

These plants have strong anti-inflammatory, anti-oxidant, and anti-arthritic effects in different study designs of rheumatoid arthritis with negligible side effects. Phytomedicines could revolutionize pharmacology as they act through alternative pathways hence seeming biocompatible.

Secreted PD-L1 alleviates inflammatory arthritis in mice through local and systemic AAV gene therapy

Introduction

Rheumatoid arthritis (RA) primarily affects the joints but can also affect multiple organs and profoundly impacts patients' ability to carry out daily activities, mental health, and life expectancy. Current treatments for RA are limited in terms of duration, efficacy, and adverse effects. PD-L1 is a checkpoint protein that plays important roles in immune regulation and has been implicated in the initiation and progression of multiple autoimmune diseases.

Method

In a previous study, we demonstrated that intra-articular injection with adeno-associated virus (AAV) vectors encoding wild type PD-L1 improved local inflammation in the joint in the collagen-induced arthritis (CIA) mouse model of RA. To further improve efficacy, we explored AAV-mediated delivery of the soluble PD-L1 (sPD-L1) to CIA mice.

Result

After intra-articular injection of AAV6 vectors expressing the optimal isoform of sPD-L1 (shPD-L1), more potency was observed when compared to wild type PD-L1, with a lower dose of AAV6/shPD-L1 needed for arthritis improvement. To study the therapeutic effect of systemic expression of sPD-L1, we administered AAV8/shPD-L1 gene therapy in CIA mice via retro-orbital injection and found significant improvements in joint inflammation and paw swelling, exhibiting similar phenotypes to that in naïve mice. The levels of total immunoglobulin and anti-collagen specific antibodies were lower in AAV8/shPD-L1 treated CIA mice than those in controls. The levels of pro-inflammatory cytokines in blood were also significantly decreased in shPD-L1 treated mice. Additionally, T cell apoptosis rates in the spleen showed a 2-fold increase in treated mice. Finally, we investigated the therapeutic effect of AAV/shPD-L1 via intramuscular injection. After injection of AAV6/shPD-L1, decreased paw swelling, reduced joint inflammation, and lower levels of pro-inflammatory cytokines in blood were achieved. The therapeutic effect of shPD-L1 was dose dependent via intramuscular treatment with AAV vectors.

Conclusion

In conclusion, the findings in this study suggest that intra-articular injection of AAV vectors encoding sPD-L1 results in greater therapeutic benefit on arthritis, and systemic AAV/sPD-L1 is able to block the development of inflammatory arthritis with inhibition of the systemic immune response, underlining the potential of gene therapy with systemic delivery of shPD-L1 via AAV vectors in RA.

Network Pharmacology and Experimental Verification of Si Shen Decoction Regulating FABP4/PPARγ/NFκB Pathway in the Treatment of Collagen-induced Arthritis

AIM

This study aimed to investigate the mechanism of Si Shen Decoction (SSD) in rats with Collagen-Induced Arthritis (CIA).

BACKGROUND

Rheumatoid arthritis (RA) is a complex immune disease characterized by bilateral symmetrical multi-joint pain and swelling. SSD has shown good results in treating RA in clinical applications, but its mechanism of action remains unclear.

OBJECTIVE

To investigate the mechanism of SSD in rats with Collagen-Induced Arthritis (CIA).

METHODS

Bioinformatics and network pharmacology analyses were used to predict the possible treatment targets and signaling pathways. Elisa, Western blotting, and quantitative real-time polymerase chain reaction were used to verify the mechanism of SSD in the treatment of RA.

RESULTS

FABP4, MMP9, and PTGS2 were the most common predicted therapeutic targets. SSD treatment significantly reduced synovitis, ankle swelling and bone erosion in CIA rats. The SSD group also significantly reduced the serum secretion of CRP, TNFα, and IL1β, decreased mRNA levels of FABP4, IKKα, and p65 in the synovial membrane, but increased PPARγ. Western blot showed that SSD treatment could significantly reduce the expression of FABP4, IKKα, and phosphorylated p65 (p-p65) proteins in the synovium. SSD was found to inhibit the FABP4/PPARγ/NFκB signaling pathway and reduce the inflammatory response in CIA rats. The therapeutic effect of SSD was significant with the increase of dose.

CONCLUSION

SSD can relieve joint symptoms in CIA rats and alleviate inflammation by inhibiting the FABP4/PPARγ/NFκB signaling pathway. The effect of high-dose SSD was more prominent.

Phosphotungstic acid-enhanced micro-computed tomography and RNA sequencing provide a new perspective on temporomandibular joint arthritis induced by complete Freund's adjuvant and collagen-induced arthritis in rat models

Background/Purpose

Temporomandibular joint (TMJ) arthritis causes inflammation and degradation of the mandibular condylar cartilage and subchondral bone. Complete Freund's adjuvant (CFA) and collagen-induced arthritis (CIA) are models for studying TMJ arthritis. While micro-computed tomography (micro-CT) is crucial for three-dimensional (3D) bone analysis, it has limitations in imaging nonmineralized tissues. Phosphotungstic acid (PTA) enhances soft tissue contrast. However, research on the 3D imaging of mandibular condylar cartilage and the molecular mechanisms of CFA- and CIA-induced arthritis remains unclear. This study aimed to investigate the bone and PTA-stained cartilage in the mandibular condyle using 3D reconstruction and explore the characteristics of enriched gene ontology terms underlying CFA- and CIA-induced TMJ arthritis in rat models.

Materials and methods

Rat mandibular condyles were collected from control, CFA, and CIA groups. Live micro-CT created 3D bone structures, and PTA-enhanced micro-CT constructed 3D mandibular condylar cartilage. Gene ontology enrichment analysis identified enriched gene ontology terms from differentially expressed genes through RNA sequencing.

Results

Major deformities in cartilage volume and bone morphology were observed in the arthritis-induced groups. The CIA group exhibited significant correlations between cartilage volume and bone parameters changes. Gene ontology enrichment analysis indicated fewer terms with upregulated differentially expressed genes related to inflammation and immune response in the CIA group than in the CFA group.

Conclusion

This study reveals distinct responses between CFA- and CIA-induced TMJ arthritis models. The CIA group exhibited strong correlations between cartilage volume and bone parameter changes and had less pronounced inflammation and immune response than the CFA group.

Praelolide alleviates collagen-induced arthritis through increasing catalase activity and activating Nrf2 pathway

BACKGROUND

Marine diterpenes represent a promising reservoir for identifying potential anti-rheumatoid arthritis (RA) candidates. Praelolide is a gorgonian-derived briarane-type diterpenoid with antioxidative and anti-osteoclastogenetic properties.

OBJECTIVE

This study aims to evaluate the therapeutic efficacy of praelolide against RA and investigate its underlying mechanisms both in vivo and in vitro.

METHOD

Collagen-induced arthritis (CIA) mice and human RA fibroblast-like synoviocyte MH7A cells were employed for bioassays. The VisuGait system was utilized to assess gait dysfunction resulting from joint pain. Histopathological changes in ankle and synovial tissues were evaluated using micro-computed tomography, hematoxylin and eosin staining, Safranin-O/Fast Green staining, tartrate resistant acid phosphatase staining, and immunohistochemistry. Fluorescence spectroscopy, circular dichroism, and surface plasmon resonance were employed to investigate interactions between praelolide and catalase. The production of inflammatory cytokines and expression levels of proteins were assessed using ELISA and Western blotting, respectively.

RESULT

Praelolide significantly reduced paw swelling and arthritis scores, improved gait deficits, and restored synovial histopathological alterations and bone erosion in CIA mice. In vivo and in vitro, praelolide effectively decreased the expression and production of inflammatory cytokines such as interleukin (IL)-1β and IL-6. Additionally, praelolide inhibited osteoclastogenesis on bone surface of the ankle joints and in a tumor necrosis factor-α (TNF-α)-induced MH7A/bone marrow-derived macrophages (BMMs) co-culture system, and it strongly suppressed reactive oxygen species (ROS) production. Mechanistically, praelolide modulated catalase through non-covalent interactions, inducing conformational alterations that enhanced catalase activity and stability against time- and temperature-induced degradation. Further investigation revealed that praelolide significantly upregulated the expression of Nrf2, subsequently activating downstream antioxidant enzymes.

CONCLUSION

Praelolide markedly alleviated synovial inflammation and bone destruction in CIA mice by enhancing catalase activity and activating the Nrf2 pathway to reduce disease-related ROS accumulation, highlighting praelolide as a promising candidate for multitarget treatment of RA.

Sophoricoside reduces inflammation in type II collagen-induced arthritis by downregulating NLRP3 signaling

Immune responses, especially NLRP3 signaling in macrophages, play critical roles in rheumatoid arthritis (RA), an autoimmune and inflammatory disease. In this study, we aimed to identify novel therapies for RA. We focused on sophoricoside (SOP), an isoflavone glycoside isolated from Sophora japonica. We predicted the targets of SOP and performed a Gene Ontology analysis to assess its effects. The results suggested that SOP is related to inflammation regulation. We verified these findings by performing in vitro experiments with M1 macrophages differentiated from human peripheral blood monocytes (THP-1 cells). Sophoricoside administration reduced inflammatory activity and NLRP3, Caspase-1, and IL-1β protein levels in macrophages. In addition, SOP and triptolide (TP) was administered intragastrically to male SD rats (n = 40) in a collagen-induced arthritis model. We observed that SOP and TP reduced the inflammatory responses and symptoms of RA. Moreover, unlike TP, SOP showed no liver or kidney toxicity in rats. In conclusion, SOP reduces inflammation in type II collagen-induced arthritis by downregulating NLRP3 signaling and has potential for future clinical applications as an ideal therapy for RA.

High Humidity Alters Myeloid-Derived Suppressor Cells in Spleen Tissue: Insights into Rheumatoid Arthritis Progression

Background

Rheumatoid arthritis (RA) is an autoimmune disease characterized by joint inflammation and bone destruction, leading to severe complications. Previous research has suggested that high humidity conditions may exacerbate RA, however, the underlying mechanisms remain unclear. Furthermore, there is a lack of evidence linking humidity to the worsening of RA symptoms in animal models.

Methods

The Collagen-induced arthritis (CIA) mouse model was established using C57BL/6 mice. The arthritis status of the mice was evaluated under two distinct humidity conditions (50% and 80%). The aim of the present study was to investigate the impact of elevated humidity levels on the types of splenic cells present using mass spectrometry flow. Additionally, the study utilized MDSCs, which are significantly upregulated by high humidity, to assess the levels of oxidative stress and conducted mRNA sequencing of sorted MDSCs to investigate their impact on arthritis in CIA mice.

Results

Compared to normal humidity, high humidity exacerbated arthritis incidence in mice, resulting in increased arthritis scores, swelling, serum autoantibodies (anti-COII and anti-CCP), and upregulation of pro-inflammatory cytokines. Significant variations were observed in the spleen index under high humidity condition, accompanied by noticeable inflammatory alterations. Moreover, elevated humidity levels induced a substantial modulation in MDSCs population in the spleen of CIA mice, along with alterations in oxidative stress markers such as heightened serum ROS levels, and increased expression of COX, SOD, and Nrf2 mRNA. Following successful sorting of MDSCs, mRNA sequencing revealed a decrease in the expression of Rap1 signaling pathway under high humidity environment, which may contribute to the increase of MDSCs cells and aggravate the progression of RA disease.

Conclusion

A comprehensive analysis of the available data reveals a detrimental impact of high humidity on MDSCs numbers within spleen tissue, with potential implications for the development of RA.

Phytochemical, Cytoprotective Profiling, and Anti-Inflammatory Potential of Colchicum luteum in Rheumatoid Arthritis: An Experimental and Simulation Study

BACKGROUND

Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by severe pain, inflammation, and joint deformity. Currently, it affects 1% of the population, with a projection to exceed 23 million cases by 2030. Despite significant advancements, non-steroidal anti-inflammatory drugs (NSAIDs), the first line of treatment, are associated with a range of adverse effects. Consequently, plant-based derivatives are being utilized as an effective alternative. This study evaluates the anti-inflammatory and safety profile of Colchicum luteum hydroethanolic extract (CLHE) in comparison to NSAIDs, with a focus on COX-2 and TNFα inhibition.

METHODS

CLHE potential was evaluated by phytochemical screening and in vitro bioactivity assays. Toxicity profile was conducted in Human Colon Epithelial Cells (HCEC) and Balb/c mice. Anti-inflammatory potential was explored in a collagen-induced arthritic (CIA) mice model. Bioactive compounds were identified computationally from GCMS data and subjected to docking and simulation studies against COX2 and TNFα.

RESULTS

CLHE demonstrated significant antioxidant (IC-50 = 6.78 µg/mL) and anti-inflammatory (IC-50 = 97.39 µg/mL) activity. It maintained 50% cell viability at 78.5 μg/µL in HCEC cells and exhibited no toxicity at a dose of 5000 mg/kg in mice. In the CIA model, CLHE significantly reduced paw swelling, arthritic scoring, C-reactive protein levels, and spleen indices, outperforming ibuprofen. Expression analysis confirmed the downregulation of COX-2, TNFα, and MMP-9. Histopathological analysis indicated the superior efficacy of CLHE compared to ibuprofen in reducing inflammation, synovial hyperplasia, and bone erosion. Computational studies identified compound-15 (CL15), (4-(4,7-dimethoxy-1,3-benzodioxol-5-yl)-2-oxo pyrrolidine-3-carboxylic acid), a non-toxic compound with strong binding affinities to COX-2 (-12.9 KJ/mol), and TNF-α (-5.8 KJ/mol).

CONCLUSIONS

The findings suggest the potential of Colchicum luteum as a safer, anti-inflammatory, and multi-targeted alternative to NSAIDs for RA treatment.

Apical periodontitis as an aggravating factor for the severity of rheumatoid arthritis: An animal study

AIM

The present study investigated the influence of apical periodontitis (AP) on the severity of rheumatoid arthritis (RA) using a Wistar rat model.

METHODOLOGY

Forty male Wistar rats were distributed across four groups (n = 10) based on the induction of RA and AP: Control, RA, AP, and RA + AP. RA was induced through two immunisations with type II collagen emulsified in incomplete Freund's adjuvant, followed by one immunisation with complete Freund's adjuvant. After 21 days of RA induction, AP was induced by exposing the pulp of four molars. Animals were euthanized after 28 days of pulp exposure. Through the experiment, visual and behavioural assessments tracked RA development and the knees and hind paw joints were measured. Micro-computed tomography scans of knees and hind paws, as well as mandibles and maxillae, were conducted to evaluate RA severity and the presence of AP, respectively. Serum samples were collected to analyse proinflammatory cytokines (IL-1β, IL-2, IL-17, and TNF-α). Non-parametric data were analysed using the Kruskal-Wallis test followed by Student-Newman-Keuls test, while one-way anova followed by Tukey's test was performed for parametric data. A significance level of 5% was employed.

RESULTS

All molars submitted to access cavity developed AP. All joints subjected to arthritis induction developed the disease, with AP + RA demonstrating a higher arthritis severity when compared to the RA group (p < .05). RA + AP group displayed a significantly larger hind paw and knee circumference compared to the RA group (p < .05). Micro-CT images of RA and RA + AP groups revealed joints with erosions and bone deformities, with a significantly lower bone surface density, lower trabecular number and higher trabecular separation in the hind paw and a significantly lower percent bone volume and higher trabecular separation in the knees of RA + AP group compared to RA group (p < .05). RA + AP group exhibited a significantly higher level of TNF-α and a lower level of IL-2 compared to all other groups (p < .05). Both RA and RA + AP groups had significantly higher IL-17 levels (p < .05), while there was no significant difference in IL-1β levels among the groups (p > .05).

CONCLUSION

The findings from this study underscore a possible relationship between apical periodontitis and the exacerbation of rheumatoid arthritis.

Low Iron Diet Improves Clinical Arthritis in the Mouse Model of Collagen-Induced Arthritis

Background: In response to inflammation, the absorption of nutritional iron is restricted. Since the pathophysiological significance of the presence and uptake of iron in chronic inflammation is still unknown, we tested the effect of a low iron diet on the clinical course of arthritis in the mouse model of collagen-induced arthritis (CIA). Methods: Six- to eight-week-old male DBA/1 mice were fed either a normal (51 mg/kg) or a low iron diet (5 mg/kg) starting four weeks before the first immunization. From day 4 after the second collagen booster made on day 25, the development of arthritis was regularly monitored until the end of the experiment (day 34), using a standard clinical arthritis score. Concentrations of mouse anti-bovine and anti-mouse collagen type 2 IgG antibodies were measured by ELISA; blood cell counts were performed and mediators of inflammation, tissue matrix degradation, oxygenation and oxidative stress were measured in the mouse sera of both diet groups at the end of the experiment by bead-based multiplex assay. Fe2+, Fe3+, oxidized and reduced glutathione (GSH and GSSG) and malondialdehyde (MDA) were quantified in whole paw tissue by ELISA. Quantitative PCR was performed in the tissues for glutathione peroxidase 4 and other key regulator genes of iron metabolism and ferroptosis. We used nonparametric tests to compare cross-sectional data. Nonlinear regression models were used for longitudinal data of the arthritis scores. Results: Mice fed a low iron diet showed a significantly less severe course of arthritis compared to mice fed a normal iron diet (p < 0.001). The immune response against bovine and mouse type 2 collagen did not differ between the two diet groups. Mice fed a low iron diet exhibited significantly lower serum levels of tissue inhibitor of metalloproteinase-1 (TIMP-1), a central regulator of inflammation and tissue matrix degradation (p < 0.05). In addition, a low iron diet led to a significant reduction in red blood cell indices, indicating restricted iron uptake and latent iron deficiency, but had no effect on hemoglobin concentrations or red blood cell counts. There were no differences between the dietary groups in Fe2+ or Fe3+ content in the paws. Based on calculation of the GSH/GSSG ratio and high MDA levels, high oxidative stress and lipid peroxidation were likewise detected in the paws of both diet groups of mice. Consequently, no differences associated with gene expression of key regulators of iron metabolism and ferroptosis could be detected between the paws of both diet groups. Conclusions: Restricted dietary iron intake alleviates immune-mediated inflammation in CIA without causing anemia. This finding suggests a promising option for dietary treatment of arthritis in inflammation. The underlying mechanism causing reduced arthritis may be linked to the complex regulatory network of TIMP-1 and appears to be independent from the local iron levels, oxidative stress and ferroptosis in the synovial tissues.

Omics-based pharmacological evaluation reveals Yuanhu Zhitong oral liquid ameliorates arthritis by regulating PKC/ERK/NF-κB signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Successful use of herbal medicine in the treatment of rheumatoid arthritis (RA) creates opportunities for alternative therapies. Yuanhu Zhitong oral liquid (YZOL) is an herbal preparation known for its potent analgesic and anti-inflammatory properties in traditional use. However, the pharmacological mechanism of YZOL for treating RA remains unclear.

AIM OF THE STUDY

The aim of this study was to evaluate the efficacy of YZOL in the treatment of RA and to explore its potential mechanisms through omics analysis.

MATERIALS AND METHODS

Type II collagen was used to induce an arthritis rat model. The effects of YZOL on paw swelling, inflammatory cytokines, oxidative stress, and histopathological changes were systematically investigated. A pathway-driven transcriptomic analysis was performed to identify key signaling pathways associated with YZOL therapy. The key alterations were validated by qRT-PCR, Western blot, and immunohistochemistry assays.

RESULTS

YZOL significantly attenuated arthritis progression, reduced paw swelling rate, and lowered arthritis score in CIA rats. YZOL also inhibited systemic inflammation and associated oxidative stress during RA. Transcriptomic analysis identified 341 genes with significantly altered expression following YZOL treatment. These genes were enriched in inflammation-related pathways, particularly in the NF-κB and MAPK signaling pathways. In addition, we discovered that YZOL can alleviate inflammation in the local synovial tissue. The effect of YZOL was confirmed by the suppression of PKC/ERK/NF-κB p65 signaling at systemic and local levels.

CONCLUSIONS

This study provides novel evidence that YZOL treatment ameliorates RA by suppressing the PKC/ERK/NF-κB pathway, suggesting its potential as an alternative therapy for RA.

Chinese traditional medicine DZGP beneficially affects gut microbiome, serum metabolites and recovery from rheumatoid arthritis through mediating NF-κB signaling pathway

Rheumatoid arthritis (RA) is globally treated with several commercially available anti-inflammatory and analgesic drugs, which pose adverse side effects in many cases. Due to increasing population affected by autoimmune disorder of joints inflammation, it is crucial to use natural therapies, which are less toxic at metabolic level and promote gut health. In this study, we investigated the potential role of a locally developed traditional Chinese medicine (TCM), namely Duzheng tablet (DZGP) in controlling the RA. For this purpose, we introduced RA in male mice and divided them into 5 different groups. High throughput transcriptome analysis of synovial cells after DZGP treatment in arthritic mice revealed a significant alteration of gene expression. The correlation analysis of transcriptome with metabolites revealed that DZGP specifically targeted the B cells mediated immunity pathways. Treatment with DZGP inhibited the cytokines production, while reducing the production of inflammatory TNF-α, which led to the alleviation of inflammatory response in arthritic mice. Additionally, we applied integrated approach using 16S rDNA sequencing to understand the microbial population in relation to metabolites accumulation. The results showed that DZGP promoted the healthy gut microbiota by maintaining the ratio of Firmicutes and Bacteroidota and introduction of two additional phyla namely, Verrucomicrobiota and Cyanobacteria. Therefore, it is concluded that DZGP offers an advantage over commercial drug by changing the metabolic profile, gut microbiota while exhibiting lower cellular toxicity.

IGF2BP2 regulates the inflammation of fibroblast-like synoviocytes via GSTM5 in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease with an unknown etiology. RA cannot be fully cured and requires lengthy treatment, imposing a significant burden on both individuals and society. Due to the lack of specific drugs available for treating RA, exploring a key new therapeutic target for RA is currently an important task. Activated fibroblast-like synoviocytes (FLSs) play a crucial role in the progression of RA, which release interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α resulting in abnormal inflammatory reaction in the synovium. A previous study has highlighted the correlation of m6A reader insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) with inflammation-related diseases in human. However, the role of IGF2BP2 in the inflammatory reaction of FLSs during RA progression has not been assessed. In this study, IGF2BP2 expression was decreased in the synovial tissues of RA patients and collagen-induced arthritis (CIA) rats. Intra-articular injection of an adeno-associated virus (AAV) vector overexpressing IGF2BP2 relieved paw swelling, synovial hyperplasia and cartilage destruction in CIA rats. IGF2BP2 overexpression also inhibited lipopolysaccharide (LPS)-mediated RA fibroblast-like synoviocytes (RA-FLSs) migration and invasion accompanied by a decreased level of inflammatory factors in vitro. Conversely, IGF2BP2 suppression promoted RA-FLSs migration and invasion with an elevated level of inflammatory factors in vitro. The sequencing result showed that glutathione S-transferase Mu 5 (GSTM5), a key antioxidant gene, was the target mRNA of IGF2BP2. Further experiments demonstrated that IGF2BP2 strengthened the stability of GSTM5 mRNA, leading to weakened inflammatory reaction and reduced expression of matrix metalloproteinase 9 and 13 (MMP9, MMP13). Therefore, IGF2BP2-GSTM5 axis may represent a potential therapeutic target for RA treatment.

Pharmacological and immunomodulatory modes of action of medically important phytochemicals against arthritis: A molecular insight

Arthritis is a common illness that affects joints and it may result in inflammation and pain. Even though arthritis usually affects older people, it can also affect children, adults, and both genders. Numerous arthritic mouse models have been developed but the CIA model of rheumatoid arthritis (RA) has received the most attention. With the use of steroids, DMARDs, and NSAIDs, therapy objectives such as reduced disease incidence and better pain management are achieved. Long-term usage of these therapeutic approaches may have negative side effects. Herbal medications are the source of several medicinal substances. Studies have explored the potential benefits of medicinal plants in treating RA. These benefits include up-regulating antioxidant potential, inhibiting cartilage degradation, down-regulating inflammatory cytokines such as NF-kB, IL-6, and TNF-α, and suppressing oxidative stress. In this review, we systematically discuss the role of traditional medicinal plants in rheumatoid arthritis (RA) disease treatment. The role of different medicinal plants such as Curcuma longa, Syzygium aromaticum, Zingiber officinale and Withania somnifera, against arthritis is discussed in this review.

Preventive and therapeutic effects of low-dose whole-body irradiation on collagen-induced rheumatoid arthritis in mice

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by progressive joint inflammation, resulting in cartilage destruction and bone erosion. It was reported that low-dose radiation modulates immune disease. Here, we investigated whether low-dose whole-body irradiation has preventive and therapeutic effects in collagen-induced RA (CIA) mouse models. Fractionated low-dose irradiation (0.05 Gy/fraction, total doses of 0.1, 0.5 or 0.8 Gy) was administered either concurrently with CIA induction by Type II collagen immunization (preventive) or after CIA development (therapeutic). The severity of CIA was monitored using two clinical parameters, paw swelling and redness. We also measured total Immunoglobulin G (IgG) and inflammatory cytokines (interleukine (IL)-6, IL-1β and tumor necrosis factor-alpha (TNF-α)) in the serum by enzyme-linked immunosorbent assay, and we evaluated histological changes in the ankle joints by immunohistochemistry and hematoxylin and eosin staining. Low-dose irradiation reduced CIA clinical scores by up to 41% in the preventive model and by 28% in the therapeutic model, while irradiation in the preventive model reduced the typical CIA incidence rate from 82 to 56%. In addition, low-dose irradiation in the preventive model decreased total IgG by up to 23% and decreased IL-1β and TNF-α by 69 and 67%, and in the therapeutic model, decreased total IgG by up to 35% and decreased IL-1β and IL-6 by 59 and 42% with statistical significance (P < 0.01, 0.05 and 0.001). Our findings demonstrate that low-dose radiation has preventive and therapeutic anti-inflammatory effects against CIA by controlling the immune response, suggesting that low-dose radiation may represent an alternative therapy for RA, a chronic degenerative immune disease.

Anti-Inflammatory Effects of a Novel Nuclear Factor-κB Inhibitory Derivative Derived from Pyrazolo[3,4-d]Pyrimidine in Three Inflammation Models

Nuclear factor-κB (NF-κB) plays a central role in inflammatory responses, and its physiologic functions are essential for cell survival and proliferation. Currently, drugs targeting NF-κB inhibition have not yet been applied in clinical practice. We investigated the physiologic effect of a novel NF-κB inhibitory compound, 1H-pyrazolo[3,4-d]pyrimidin-4-amine derivative (INH #1), on three inflammatory animal models. The pharmacokinetics were measured by liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis. Acute hepatitis was induced by administrating lipopolysaccharide (LPS) and D-(+)-galactosamine hydrochloride followed by the analysis of survival time and inflammatory mediators. Collagen-induced arthritis (CIA) was induced by immunization with type II collagen (CII), and serum-transfer arthritis (STA) was caused by injecting K/BxN mice serum. Clinical and histologic scores were evaluated in both arthritis models. Immune cell subset analysis, CII-induced interferon-gamma (IFN-γ) production and proliferation, and measurement of anti-CII IgG antibodies were performed in the CIA model. In the acute hepatitis model, INH #1 suppressed tumor necrosis factor-α (TNF-α) production and prevented early death in a dose-dependent manner. INH #1 significantly attenuated arthritis scores and joint inflammation in both arthritis models. Additionally, in the CIA model, dendritic cells (DCs) in the regional lymph nodes were decreased in the treated mice and antigen-induced IFN-γ production and cell proliferation in splenocytes were inhibited, whereas the titers of anti-CII IgG antibodies were comparable regardless of the treatment. Here we revealed that INH #1 exerted anti-inflammatory effects in vivo via inhibition of inflammatory mediators and suppression of cellular immune responses. This compound could be a novel candidate for inhibition of NF-κB in certain inflammatory diseases. SIGNIFICANCE STATEMENT: A novel nuclear factor-κB (NF-κB) inhibitory compound, 1H-pyrazolo[3,4-d]pyrimidin-4-amine derivative (INH #1), which retains physiologically essential NF-κB bioactivity, suppressed inflammation in three different mouse models: the acute hepatitis model, the collagen-induced arthritis model, and the K/BxN serum-transfer arthritis model. These results suggest that this compound could be a novel and potent anti-inflammatory agent.

Inhibitory effects of Acanthopanax sessiliflorus Harms extract on the etiology of rheumatoid arthritis in a collagen-induced arthritis mouse model

BACKGROUND

The biological function of Acanthopanax sessiliflorus Harm (ASH) has been investigated on various diseases; however, the effects of ASH on arthritis have not been investigated so far. This study investigates the effects of ASH on rheumatoid arthritis (RA).

METHODS

Supercritical carbon dioxide (CO2) was used for ASH extract preparation, and its primary components, pimaric and kaurenoic acids, were identified using gas chromatography-mass spectrometer (GC-MS). Collagenase-induced arthritis (CIA) was used as the RA model, and primary cultures of articular chondrocytes were used to examine the inhibitory effects of ASH extract on arthritis in three synovial joints: ankle, sole, and knee.

RESULTS

Pimaric and kaurenoic acids attenuated pro-inflammatory cytokine-mediated increase in the catabolic factors and retrieved pro-inflammatory cytokine-mediated decrease in related anabolic factors in vitro; however, they did not affect pro-inflammatory cytokine (IL-1β, TNF-α, and IL-6)-mediated cytotoxicity. ASH effectively inhibited cartilage degradation in the knee, ankle, and toe in the CIA model and decreased pannus development in the knee. Immunohistochemistry demonstrated that ASH mostly inhibited the IL-6-mediated matrix metalloproteinase. Gene Ontology and pathway studies bridge major gaps in the literature and provide insights into the pathophysiology and in-depth mechanisms of RA-like joint degeneration.

CONCLUSIONS

To the best of our knowledge, this is the first study to conduct extensive research on the efficacy of ASH extract in inhibiting the pathogenesis of RA. However, additional animal models and clinical studies are required to validate this hypothesis.

Therapeutic activity and biodistribution of a nano-sized polymer-dexamethasone conjugate intended for the targeted treatment of rheumatoid arthritis

Rheumatoid arthritis is a chronic inflammatory autoimmune disease caused by alteration of the immune system. Current therapies have several limitations and the use of nanomedicines represents a promising strategy to overcome them. By employing a mouse model of adjuvant induced arthritis, we aimed to evaluate the biodistribution and therapeutic effects of glucocorticoid dexamethasone conjugated to a nanocarrier based on biocompatible N-(2-hydroxypropyl) methacrylamide copolymers. We observed an increased accumulation of dexamethasone polymer nanomedicines in the arthritic mouse paw using non-invasive fluorescent in vivo imaging and confirmed it by the analysis of tissue homogenates. The dexamethasone conjugate exhibited a dose-dependent healing effect on arthritis and an improved therapeutic outcome compared to free dexamethasone. Particularly, significant reduction of accumulation of RA mediator RANKL was observed. Overall, our data suggest that the conjugation of dexamethasone to a polymer nanocarrier by means of stimuli-sensitive spacer is suitable strategy for improving rheumatoid arthritis therapy.

Clinical Evaluation of Collagen-Induced Arthritis in Female Lewis Rats: A Comprehensive Analysis of Disease Progression and Severity

OBJECTIVE

The collagen-induced arthritis (CIA) model is the most commonly studied autoimmune model of rheumatoid arthritis (RA). In this study, we investigated the usefulness of collagen type II emulsified in Freund's incomplete adjuvant (CII/IFA) as a suitable method for establishing RA in Lewis rats. The aim of the present study was to present a straightforward and effective method for inducing CIA in rats.

MATERIALS AND METHODS

In this experimental study, animals were divided into two equal groups (n=5); control and CIA. Five rats were injected intradermally at the base of the tail with a 0.2 ml CII/IFA emulsion. On the seventh day, a 0.1 ml CII/IFA emulsion booster was injected. Arthritis symptoms that arose were evaluated at clinical, histological, radiological, and at protein expression levels to find out if the disease had been induced successfully.

RESULTS

Our finding showed a decreasing trend in the body weight during the RA induction period, while the arthritis score and paw thickness were increased during this period. The results of the enzyme-linked immunosorbent assay (ELISA) for serum samples revealed that the levels of proinflammatory cytokines, interleukin (IL)-1β, IL-6, IL-17, and tumor necrosis factor (TNF)-α and anti-CII IgG were significantly increased in CIA rats compared to the control group. After CIA induction, the level of anti-inflammatory protein IL-10 was decreased significantly. Radiographic examination of the hind paws showed soft tissue swelling, bone erosion, and osteophyte formation in CIA rats. Additionally, based on histological evaluations, the hind paws of the CIA group showed pannus formation, synovial hyperplasia, and bone and cartilage destruction.

CONCLUSION

It seems that CII/IFA treatment can be an appropriate and effective method to induce RA disease in Lewis rats. This well-established and well-characterized CIA model in female Lewis rats could be considered to study aspects of RA and develop novel anti-arthritic agents.

Voluntary wheel running from early adolescence reduces disease progression, and anxiety- and depression-related symptoms in an adult male mouse model of rheumatoid arthritis

Rheumatoid arthritis (RA) is a multifactorial autoimmune disease that progressively destroys synovial joints and leads to chronic systemic inflammation. This autoimmune disorder is associated with increased anxiety- and depression-related symptoms, which reduces quality of life. Clinical and experimental evidence suggests that higher physical activity from early adolescence may prevent chronic diseases and reduce the risk of mental health problems in adulthood. This study aimed to assess whether voluntary wheel running from early adolescence can decrease clinical symptoms, anxiety- and depression-related behaviors in adult mice with rheumatoid arthritis. Adolescent male mice were exposed to voluntary wheel running until adulthood and got collagen-induced arthritis. We measured body weight, the thickness of the hind paw and knee joint (clinical signs), anxiety- and depression-related behaviors, serum testosterone, and cytokines (IFN-γ IL-1β, IL-6, TNF-α, IL-10). The findings showed that collagen-induced arthritis resulted in anxious-like behavior, increased anhedonia, elevated IL-6, IL-1β, TNF-α, and IFN-γ, and decreased testosterone levels in the serum of mice. However, no change was observed in behavioral despair. We found that higher physical activity from early adolescence significantly reduced the severity of clinical signs, anxiety- and anhedonia-like behaviors, and decreased behavioral despair in RA-induced mice. In addition, the running wheel exposure normalized RA-induced abnormalities in testosterone and inflammatory cytokines in mice. Altogether, this study suggests that higher physical activity from early adolescence may make mice less vulnerable or resistant to RA-induced clinical symptoms and anxiety- and depression-related behaviors by changing testosterone and inflammatory cytokines productions in adulthood.

Chronic stress predisposes to the aggravation of inflammation in autoimmune diseases with focus on rheumatoid arthritis and psoriasis

The global incidence of autoimmune diseases is on the rise, and many healthcare professionals believe that chronic stress plays a prominent role in both the aggravation and remission of these conditions. It is believed that prolonged exposure to stress is associated with neuroimmune axis malfunction, which eventually dysregulates multiple immunological factors as well as deregulates autoimmune responses that play a central role in various autoimmune diseases, including rheumatoid arthritis and psoriasis. Herein, we performed validation of an 8-week long rat model of chronic unpredictable stress (CUS) which consisted of exposing groups of rats to random stressors daily for 8 weeks. Additionally, we developed a novel rat model combining 8-week long random stressor-induced CUS with CIA-triggered arthritis and IMQ-triggered psoriasis and have successfully used both these models to assess the role of chronic stress in the aggravation of arthritis and psoriasis, respectively. Notably, the 8-week CUS protocol extensively aggravated and prolonged both arthritis and psoriasis condition in the rat model by upregulating the release of different pro-inflammatory cytokines, dysregulation of immune cell responses and oxidative stress system, which were all related to severe inflammation. Further, CUS aggravated macroscopic features and the increase in destruction of joint tissue and epidermal thickness induced by CIA and IMQ, respectively, in rats. In conclusion, this study suggests that exposure to an 8-week long CUS paradigm aggravates the distinctive characteristics of rheumatoid arthritis and psoriasis in rats via amplifying the inflammatory circuits and immune cell responses linked to these autoimmune diseases.

High-Sucrose Diet Accelerates Arthritis Progression in a Collagen-Induced Rheumatoid Arthritis Model

SCOPE

High dietary sugar and sweeteners are suspected to cause the development of rheumatoid arthritis (RA) symptoms through the induction of proinflammatory cytokine release. However, the mechanisms by which increased dietary sugar affects RA etiology are not yet fully understood. The study uses a mouse model of collagen-induced RA (CIA) to investigate the relationship between excessive sugar consumption and RA risk.

METHODS AND RESULTS

RA-associated pathological features are assessed in the nonimmunized (NI) control group, the CIA-positive control group, and the CIA + high-sucrose diet (CIA+HS, 63% calories from sucrose) group. Compared with the CIA group, the CIA+HS group shows a greater increase in paw thickness and clinical scores, as well as, a higher degree of pannus formation and inflammation in the knee, ankle, and sole tissues. Moreover, the infiltration of immune cells is increased in the CIA+HS group. Although the expression of hepatic lipogenic genes, is not altered, that of toll-like receptor (TLR4) and IL-1β is considerably elevated in the CIA+HS group.

CONCLUSIONS

These findings suggest that excessive sucrose consumption causes hepatic fibrosis and inflammation, contributing to the pathophysiology of RA.

Sex differences in long-term effects of collagen-induced arthritis in middle-aged mice

Introduction: Rheumatoid arthritis (RA) is a chronic inflammatory disorder with high prevalence among middle-aged women. Collagen-induced arthritis (CIA) is the most widely used animal model of RA, however, sex differences and long-term effects of CIA in mice are poorly described in the literature. Aim: Therefore, the present study aimed to analyze the long-term effects of CIA on the joints of middle-aged mice of both sexes and to describe potential sex differences. Materials and methods: CIA was induced in middle-aged DBA/1J mice by immunization with bovine type II collagen and complete Freund's adjuvant. Saline was administered to control mice. Arthritis score assessment, plethysmometry, and thermal imaging of the joints were performed weekly for 15 weeks. Locomotor activity, micro-computed tomography, joint histology and biochemical analyses were performed at the end of the experiment. Results: Our results indicate a similar prevalence of arthritis in both sexes of mice-67% (8/12) of females and 89% (8/9) males with an earlier onset in males (day 14 vs. day 35). After the arthritis scores peaked on day 56 for males and day 63 for females, they steadily declined until the end of the experiment on day 105. A similar dynamics was observed in paw volume and temperature analyzing different aspects of joint inflammation. Long-term consequences including higher proteinuria (by 116%), loss of bone density (by 33.5%) and joint damage in terms of synovial hyperplasia as well as bone and cartilage erosions were more severe in CIA males compared to CIA females. There were no significant differences in locomotor activity between CIA mice and CTRL mice of any sex. Conclusion: This is the first study to describe the long-term effects of the CIA model in terms of sex differences in DBA/1J mice. Our results indicate sex differences in the dynamics, but not in the extent of arthritis. An earlier onset of arthritis and more severe consequences on joints, bones and kidneys were found in males. The underlying immune pathomechanisms responsible for the limited duration of the arthritis symptoms and the opposite sex difference in comparison to RA patients require further investigation.

Differentiated embryonic chondrocyte expressed gene-1 is a central signaling component in the development of collagen-induced rheumatoid arthritis

Rheumatoid arthritis (RA) is one of the most common autoimmune diseases and affects almost 1% of the population. Differentiated embryo-chondrocyte expressed gene-1 (DEC1) has been associated with both osteogenesis and osteoclastogenesis. RA condition is marked by inflammatory hyperplasia, and DEC1 is known to support inflammatory reactions and implicated in antiapoptosis and cell invasion. Here, our goal was to test the hypothesis that DEC1 enhances RA development induced by collagen-induced arthritis (CIA), a well-recognized protocol for developing RA animal models. DEC1^+/+ and DEC1^-/- mice were subjected to CIA protocol, and the development of RA condition was monitored. We found that CIA robustly induced RA phenotypes (e.g., synovial hyperplasia) and greatly increased the expression of proinflammatory cytokines such as TNF-α. However, these changes were detected in DEC1^+/+ but not DEC1^-/- mice. Interestingly, these very cytokines strongly induced DEC1, and such a dual role of DEC1, as an inducer for and being induced by proinflammatory cytokines, constitutes a DEC1-amplifying circuit for inflammation. Knockdown of DEC1 in human MH7A cells strongly decreased cell migration and invasion as well as the expression of genes related to RA phenotypes. The combination of DEC1-directed migration and invasion in vitro with synovial hyperplasia in vivo mechanistically establishes cellular bases on how DEC1 is involved in the development of RA phenotypes. In addition to inflammatory signaling, DEC1 functionally interacted with PI3KCA(p110α)/Akt/GSK3β, Wnt/β-catenin, and NFATc1. Such engagement in multiple signaling pathways suggests that DEC1 plays coordinated and integral roles in developing RA, one of the most common autoimmune diseases.

Advances in experimental models of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease characterized by persistent articular inflammation and joint damage. RA was first described over 200 years ago; however, its etiology and pathophysiology remain insufficiently understood. The current treatment of RA is mainly empirical or based on the current understanding of etiology with limited efficacy and/or substantial side effects. Thus, the development of safer and more potent therapeutics, validated and optimized in experimental models, is urgently required. To improve the transition from bench to bedside, researchers must carefully select the appropriate experimental models as well as draw the right conclusions. Here, we summarize the establishment, pathological features, potential mechanisms, advantages, and limitations of the currently available RA models. The aim of the review is to help researchers better understand available RA models; discuss future trends in RA model development, which can help highlight new translational and human-based avenues in RA research.

Phenolic-Compound-Rich Opuntia littoralis Ethyl Acetate Extract Relaxes Arthritic Symptoms in Collagen-Induced Mice Model via Bone Morphogenic Markers

Rheumatoid arthritis (RA) is an autoimmune disease that causes inflammation and progressive joint dysfunction. Opuntia littoralis (OL) has a high nutritional content and is thought to offer a number of health advantages. We aimed to evaluate the anti-arthritic potential of OL extracts against collagen-induced arthritis (CIA). We designed three OL cladode fractions from the concentrated aqueous extract: hexane, ethyl acetate (EAE), and hydro alcohol (HAE). We investigated the nitric oxide and MDA levels of EAE against lipopolysaccharide-induced RAW264.7 cells; then, we administered EAE to the mice with CIA to confirm the anti-inflammatory effects against RA. HPLC analysis of the OL extracts showed a high concentration of phenolic compounds in EAE. Treatment with EAE (10 and 20 mg/100 g body weight of mice) after 10 days of immunization with collagen showed a significant inhibition of joint inflammation, paw swelling, and edemas. MDA and cytokine levels (IL-1β, IL-6R, IL-6, IL-17, and IL-23) were significantly reduced. EAE effectively ameliorated COX-2, NF-kB, STAT-3, PTEN, and RANKL expression. OL-EAE therapy significantly upregulated the expression of miR-28 and miR-199a. In conclusion, the anti-inflammatory actions of OL-EAE altered the cellular localization of the inflammatory mediators, therefore preventing joint inflammation via partial epigenetic and metabolic regulations in experimental mice.

Bench to Bedside: Modelling Inflammatory Arthritis

Inflammatory arthritides such as rheumatoid arthritis are a major cause of disability. Pre-clinical murine models of inflammatory arthritis continue to be invaluable tools with which to identify and validate therapeutic targets and compounds. The models used are well-characterised and, whilst none truly recapitulates the human disease, they are crucial to researchers seeking to identify novel therapeutic targets and to test efficacy during preclinical trials of novel drug candidates. The arthritis parameters recorded during clinical trials and routine clinical patient care have been carefully standardised, allowing comparison between centres, trials, and treatments. Similar standardisation of scoring across in vivo models has not occurred, which makes interpretation of published results, and comparison between arthritis models, challenging. Here, we include a detailed and readily implementable arthritis scoring system, that increases the breadth of arthritis characteristics captured during experimental arthritis and supports responsive and adaptive monitoring of disease progression in murine models of inflammatory arthritis. In addition, we reference the wider ethical and experimental factors researchers should consider during the experimental design phase, with emphasis on the continued importance of replacement, reduction, and refinement of animal usage in arthritis research.

Short term, low dose alpha-ketoglutarate based polymeric nanoparticles with methotrexate reverse rheumatoid arthritis symptoms in mice and modulate T helper cell responses

Activated effector T cells induce pro-inflammatory responses in rheumatoid arthritis (RA) which then lead to inflammation of the joints. In this report, we demonstrate that polymeric nanoparticles with alpha keto-glutarate (aKG) in their polymer backbone (termed as paKG NPs) modulate T cell responses in vitro and in vivo. Impressively, a low dose of only three administrations of methotrexate, a clinically and chronically administered drug for RA, in conjunction with two doses of paKG NPs, reversed arthritis symptoms in collagen-induced arthritis (CIA) mice. This was further followed by significant decreases in pro-inflammatory antigen-specific T helper type 17 (TH17) responses and a significant increase in anti-inflammatory regulatory T cell (TREG) responses when CIA treated splenic cells were isolated and re-exposed to the CIA self-antigen. Overall, this study supports the concurrent and short term, low dose of paKG NPs and methotrexate for the reversal of RA symptoms.

Porous Silicon-Based Nanomedicine for Simultaneous Management of Joint Inflammation and Bone Erosion in Rheumatoid Arthritis

The lack of drugs that target both disease progression and tissue preservation makes it difficult to effectively manage rheumatoid arthritis (RA). Here, we report a porous silicon-based nanomedicine that efficiently delivers an antirheumatic drug to inflamed synovium while degrading into bone-remodeling products. Methotrexate (MTX) is loaded into the porous silicon nanoparticles using a calcium silicate based condenser chemistry. The calcium silicate-porous silicon nanoparticle constructs (pCaSiNPs) degrade and release the drug preferentially in an inflammatory environment. The biodegradation products of the pCaSiNP drug carrier are orthosilicic acid and calcium ions, which exhibit immunomodulatory and antiresorptive effects. In a mouse model of collagen-induced arthritis, systemically administered MTX-loaded pCaSiNPs accumulate in the inflamed joints and ameliorate the progression of RA at both early and established stages of the disease. The disease state readouts show that the combination is more effective than the monotherapies.

The mechanism of the anti-inflammatory effect of Oldenlandia diffusa on arthritis model rats: a quantitative proteomic and network pharmacologic study

BACKGROUND

In China, Oldenlandia diffusa (OD) has been prescribed as a therapeutic herb for rheumatoid arthritis (RA). We previously conducted a preliminary study of the anti-inflammatory effect of OD, and the purpose of this study is to further investigate its mechanism.

METHODS

We performed a quantitative proteomic analysis of synovium, identified the differentially expressed proteins, and performed bioinformatics analyses. With the help of network pharmacology, we aimed to find the key synovial proteins which OD or its key compound might influence. To verify the result, liquid chromatography-mass spectrometry (LC-MS) was applied to quantify and qualify the absorbable potential compounds of OD. The anti-inflammatory effect was evaluated by morphological, histopathological, and cytokine analyses. Target proteins were observed by immunohistochemistry (IHC) and enzyme-linked immunosorbent assay (ELISA).

RESULTS

MMP3 and CAV1 were identified as 2 of the differentially expressed proteins in RA synovium, and might be influenced by quercetin, the active compound of OD. MMP3 might be altered through atherosclerosis signaling, while CAV1 might be altered through caveolar-mediated endocytosis signaling. According to our verification, quercetin was identified as the absorbed and effective compound of OD, and it could exert an anti-inflammatory effect on the collagen-induced arthritis (CIA) model, including serum cytokine expression, synovial hyperplasia and lymphocyte infiltration, articular cartilage lesion. Quercetin could also down-regulate the synovial expression of MMP3 and CAV1, and could exert better effects at a high dose.

CONCLUSIONS

Quercetin was the main active compound of OD in the treatment of RA. OD might alleviate inflammatory responses in CIA rats by suppressing the expression of MMP3 and CAV1 through quercetin, and at a high dose, quercetin could exert a better anti-inflammatory effect.