Analysis of differentially expressed genes between rheumatoid arthritis and osteoarthritis based on the gene co-expression network

Association of integrin-β2 polymorphism and expression with the risk of rheumatoid arthritis and osteoarthritis in Egyptian patients

BACKGROUND

The genetic architecture of rheumatoid arthritis (RA) and osteoarthritis (OA) are still unclear. Although RA and OA have quite different causes, they share synovial inflammation, risk factors, and some disease-associated genes, including the integrin subunit β2 (ITGB2)/CD18 gene involved in extracellular matrix interactions and immune cell signaling. However, the functional role of ITGB2 genetic variants, its circulating expression pattern, and their clinical usefulness in RA and OA remain unexplored. Our study appraised the association of ITGB2 rs2070946 single nucleotide polymorphism with the vulnerability to RA and OA and its influence on ITGB2 mRNA expression, along with the potential of serum ITGB2 expression in RA and OA diagnosis.

METHODS

This study included 70 RA patients, 70 primary OA patients, and 60 healthy volunteers. Genotyping and gene expression analysis were performed using qPCR. Bioinformatics analysis was employed to construct the protein-protein interaction (PPI) network of ITGB2.

RESULTS

Serum ITGB2 mRNA expression was upregulated in both RA and OA compared to healthy controls. ITGB2 rs2070946 was associated with escalating risk of both diseases. RA patients harboring the rs2070946 CC or TC + CC genotypes had higher serum ITGB2 expression than the TT genotype carriers. Likewise, OA patients having the minor homozygote CC genotype had higher serum ITGB2 expression than those carrying the TT, TC or TT + TC genotypes. Serum ITGB2 expression showed profound diagnostic potential for RA and OA in receiver-operating characteristic analysis. In RA, serum ITGB2 expression positively correlated with rheumatoid factor and disease activity score 28 (DAS28). The ITGB2-PPI network enriched in cell-cell adhesion, ICAM-3 receptor activity, T-cell activation, leukocyte adhesion, complement binding, and NF-κB, tumor necrosis factor, and interleukin signaling pathways.

CONCLUSION

These findings embrace the impact of ITGB2 rs2070946 as a novel genetic biomarker of both RA and OA, which could alter the ITGB2 expression. Serum ITGB2 expression could aid in timely diagnosis of RA and OA.

Gene Expression Microarray Data Identify Hub Genes Involved in Osteoarthritis

The present study was performed to explore the underlying molecular mechanisms and screen hub genes of osteoarthritis (OA) via bioinformatics analysis. In total, twenty-five OA synovial tissue samples and 25 normal synovial tissue samples were derived from three datasets, namely, GSE55457, GSE55235, and GSE1919, and were used to identify the differentially expressed genes (DEGs) of OA by R language. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of DEGs were conducted using the Database for Annotation, Visualization, and Integrated Discovery (DAVID). A Venn diagram was built to show the potential hub genes identified in all three datasets. The STRING database was used for constructing the protein–protein interaction (PPI) networks and submodules of DEGs. We identified 507 upregulated and 620 downregulated genes. Upregulated DEGs were significantly involved in immune response, MHC class II receptor activity, and presented in the extracellular region, while downregulated DEGs were mainly enriched in response to organic substances, extracellular region parts, and cadmium ion binding. Results of KEGG analysis indicated that the upregulated DEGs mainly existed in cell adhesion molecules (CAMs), while downregulated DEGs were significantly involved in the MAPK signaling pathway. A total of eighteen intersection genes were identified across the three datasets. These include Nell-1, ATF3, RhoB, STC1, and VEGFA. In addition, 10 hub genes including CXCL12, CXCL8, CCL20, and CCL4 were found in the PPI network and module construction. Identification of DEGs and hub genes associated with OA may be helpful for revealing the molecular mechanisms of OA and further promotes the development of relevant biomarkers and drug targets.

Potential biomarkers that discriminate rheumatoid arthritis and osteoarthritis based on the analysis and validation of datasets

Background

Rheumatoid arthritis (RA) and osteoarthritis (OA) share some similar arthritic symptoms, but different mechanisms underlie the pathogenesis of these two diseases. Analysis of differentially expressed molecules in rheumatoid arthritis and osteoarthritis may assist in improving diagnosis and treatment strategies in clinical practice.

Methods

Microarray and RNA-seq data were acquired from the gene expression omnibus database. Differentially expressed genes (DEGs) were identified using Bioconductor packages. Receiver operating characteristic curves were plotted to assess performance. Gene ontology enrichment analysis was conducted using the clusterProfiler application. During validation, synovial fluid was harvested from patients who had undergone in-hospital joint replacement, in which the expression of proteins was measured using enzyme-linked immunosorbent assays.

Results

Compared with OA samples, RA samples showed 14 genes to be upregulated and 3 to be downregulated. Gene ontology analysis indicated that DEGs principally included molecules responsible for the regulation of a synovial tissue inflammatory response. Seven genes displayed a good discriminatory power with an AUC higher than 0.90. ADAMDEC1 was the biomarker that most clearly discriminated RA from OA in the database, exhibiting an AUC of 0.999, a sensitivity of 100%, and a specificity of 97.8%. Following validation, the expression levels of ADAMDEC1 in the synovial fluid from RA patients were significantly higher than those in the synovial fluid from OA patients (P < 0.05). At the cut-off value of 1957 pg/mL, ADAMDEC1 expression in the synovial fluid discriminated RA from OA with an AUC of 0.951, a specificity of 88.6%, and a sensitivity of 92.9%.

Conclusion

The differential expression of genes in RA compared with OA indicates potential targets for molecular diagnosis and treatment. The presence of ADAMDEC1 in synovial fluid is a good biomarker of RA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05277-x.

Synovial fluid proteome profile of surgical versus chemical induced osteoarthritis in rabbits

BACKGROUND

Animal models are significant for understanding human osteoarthritis (OA). This study compared the synovial fluid proteomics changes in surgical and chemical induced OA models.

METHODS

Thirty rabbits either had anterior cruciate ligament transection (ACLT) procedure or injected intra-articularly with monosodium iodoacetate (MIA, 8 mg) into the right knee. The joints were anatomically assessed, and the synovial fluid proteins analyzed using two-dimensional polyacrylamide gel electrophoresis (2DGE) and MALDI TOF/TOF mass spectrometry analysis at 4, 8 and 12 weeks. The proteins' upregulation and downregulation were compared with control healthy knees.

RESULTS

Seven proteins (histidine-rich glycoprotein, beta-actin-like protein 2 isoform X1, retinol-binding protein-4, alpha-1-antiproteinase, gelsolin isoform, serotransferrin, immunoglobulin kappa-b4 chain-C-region) were significantly expressed by the surgical induction. They characterized cellular process (27%), organization of cellular components or biogenesis (27%), localization (27%) and biological regulation (18%), which related to synovitis, increased cellularity, and subsequently cartilage damage. Three proteins (apolipoprotein I-IV precursor, serpin peptidase inhibitor and haptoglobin precursor) were significantly modified by the chemical induction. They characterized stimulus responses (23%), immune responses (15%), biological regulations (15%), metabolism (15%), organization of cellular components or biogenesis (8%), cellular process (8%), biological adhesions (8%) and localization (8%), which related to chondrocytes glycolysis/death, neovascularization, subchondral bone necrosis/collapse and inflammation.

CONCLUSIONS

The surgical induced OA model showed a wider range of protein changes, which were most upregulated at week 12. The biological process proteins expressions showed the chemical induced joints had slower OA progression compared to surgical induced joints. The chemical induced OA joints showed early inflammatory changes, which later decreased.

Epigenetically-regulated RPN2 gene influences lymphocyte activation and is involved in pathogenesis of rheumatoid arthritis

BACKGROUND

To identify RA-associated genes and to ascertain epigenetic factors and functional mechanisms underlying RA pathogenesis.

METHODS

Peripheral blood mononuclear cells (PBMC) transcriptome- and proteome- wide gene expressions were profiled in a case-control study sample. Differentially expressed genes (DEGs) were discovered and validated independently. In-house PBMC genome-wide SNP genotyping data, miRNA expression data and DNA methylation data in the same sample were utilized to identify SNPs [expression quantitative trait locus (eQTLs) and protein quantitative trait locus (pQTLs)], miRNAs, and DNA methylation positions (DMPs) regulating key DEG of interest. Lentivirus transfection was conducted to study the effects of RPN2 on T lymphocyte activation, proliferation, apoptosis, and inflammatory cytokine expression. Rpn2 protein level in plasma was quantitated by ELISA to assess its performance in discriminating RA cases and controls.

RESULTS

Twenty-two DEGs were discovered in PBMCs. The most significant DEG, i.e., RPN2, was validated to be up-regulated with RA in PBMCs. A complex regulatory network for RPN2 gene expression in PBMCs was constructed, which consists of 38 eQTL and 53 pQTL SNPs, 3 miRNAs and 2 DMPs. Besides, RPN2 expression was significantly up-regulated with RA in primary T lymphocytes, as well as in PHA-activated T lymphocytes. RPN2 over-expression in T lymphocytes significantly inhibited apoptosis and IL-4 expression and promoted proliferation and activation. PBMCs-expressed RPN2 mRNA and plasma Rpn2 protein demonstrated superior and modest performances in discriminating RA cases and controls, respectively.

CONCLUSIONS

RPN2 gene influences T lymphocyte growth and activation and is involved in the pathogenesis of RA. Rpn2 may serve as a novel protein biomarker for RA diagnosis.

Identification and validation of hub genes of synovial tissue for patients with osteoarthritis and rheumatoid arthritis

Background

Osteoarthritis (OA) and rheumatoid arthritis (RA) were two major joint diseases with similar clinical phenotypes. This study aimed to determine the mechanistic similarities and differences between OA and RA by integrated analysis of multiple gene expression data sets.

Methods

Microarray data sets of OA and RA were obtained from the Gene Expression Omnibus (GEO). By integrating multiple gene data sets, specific differentially expressed genes (DEGs) were identified. The Gene Ontology (GO) functional annotation, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways and protein–protein interaction (PPI) network analysis of DEGs were conducted to determine hub genes and pathways. The “Cell Type Identification by Estimating Relative Subsets of RNA Transcripts (CIBERSORT)” algorithm was employed to evaluate the immune infiltration cells (IICs) profiles in OA and RA. Moreover, mouse models of RA and OA were established, and selected hub genes were verified in synovial tissues with quantitative polymerase chain reaction (qPCR).

Results

A total of 1116 DEGs were identified between OA and RA. GO functional enrichment analysis showed that DEGs were enriched in regulation of cell morphogenesis involved in differentiation, positive regulation of neuron differentiation, nuclear speck, RNA polymerase II transcription factor complex, protein serine/threonine kinase activity and proximal promoter sequence-specific DNA binding. KEGG pathway analysis showed that DEGs were enriched in EGFR tyrosine kinase inhibitor resistance, ubiquitin mediated proteolysis, FoxO signaling pathway and TGF-beta signaling pathway. Immune cell infiltration analysis identified 9 IICs with significantly different distributions between OA and RA samples. qPCR results showed that the expression levels of the hub genes (RPS6, RPS14, RPS25, RPL11, RPL27, SNRPE, EEF2 and RPL19) were significantly increased in OA samples compared to their counterparts in RA samples (P < 0.05).

Conclusion

This large-scale gene analyses provided new insights for disease-associated genes, molecular mechanisms as well as IICs profiles in OA and RA, which may offer a new direction for distinguishing diagnosis and treatment between OA and RA.

Investigating the molecular control of deer antler extract on articular cartilage

BACKGROUND

Deer antler is considered as a precious traditional Chinese medicinal material and has been widely used to reinforce kidney's yang, nourish essence, and strengthen bone function. The most prominent bioactive components in deer antler are water-soluble proteins that play potential roles in bone formation and repair. The aim of this study was to explore the molecular control and therapeutic targets of deer antler extract (DAE) on articular cartilage.

METHODS

DAE was prepared as previously described. All rats were randomly divided into Blank group and DAE group (10 rats per group) after 7-day adaptive feeding. The rats in DAE group were orally administrated with DAE at a dose of 0.2 g/kg per day for 3 weeks, and the rats in Blank group were fed with drinking water. Total RNA was isolated from the articular cartilage of knee joints. RNA sequencing (RNA-seq) experiment combined with quantitative real-time polymerase chain reaction (qRT-PCR) verification assay was carried out to explore the molecular control and therapeutic targets of DAE on articular cartilage.

RESULTS

We demonstrated that DAE significantly increased the expression levels of functional genes involved in cartilage formation, growth, and repair and decreased the expression levels of susceptibility genes involved in the pathophysiology of osteoarthritis.

CONCLUSIONS

DAE might serve as a candidate supplement for maintaining cartilage homeostasis and preventing cartilage degeneration and inflammation. These effects were possibly achieved by accelerating the expression of functional genes involved in chondrocyte commitment, survival, proliferation, and differentiation and suppressing the expression of susceptibility genes involved in the pathophysiology of osteoarthritis. Thus, our findings will contribute towards deepening the knowledge about the molecular control and therapeutic targets of DAE on the treatment of cartilage-related diseases.

Retinoic Acid-Platinum (II) Complex [RT-Pt(II)] Protects Against Rheumatoid Arthritis in Mice via MEK/Nuclear Factor kappa B (NF-κB) Pathway Downregulation

Background

Rheumatoid arthritis (RA) is an inflammatory disorder that is present in approximately 1% of the world’s population. This study was aimed to investigate the effect of retinoic acid-platinum (II) complex [RT-Pt(II)] on rheumatoid arthritis (RA) and to explore the mechanism involved.

Material/Methods

MH7A cell viability was determined by MTT assay and apoptosis was assessed using FACSCalibur flow cytometry. RT-PCR and Western blot assays were used for assessment of mRNA and proteins levels.

Results

Treatment of rheumatoid arthritis with RT-Pt(II) significantly reduced the levels of IL-1β, IL-6, IL-8, MMP-1, and MMP-13 in synovial fluid of mice in a dose-dependent manner. The expression of iNOS and COX-2 mRNA and protein in rheumatoid arthritis rats was also significantly inhibited by treatment with RT-Pt(II). The TNF-α-induced proliferation of MH7A cells was alleviated by RT-Pt(II) treatment in a concentration-dependent manner. Moreover, RT-Pt(II) treatment induced apoptosis and caused arrest of cell cycle in MH7A cells. The activation of MEK/NF-κB pathway was downregulated by RT-Pt(II) treatment in MH7A cells.

Conclusions

In summary, the present study demonstrated that RT-Pt(II) inhibits TNF-α-induced inflammatory response, suppresses cell viability, and induces apoptosis in rheumatoid arthritis synovial cells. Moreover, RT-Pt(II) exhibited its effect through targeting the MEK/NF-κB pathway. Therefore, RT-Pt(II) can be used for the development of treatments for rheumatoid arthritis.

Bioinformatics analysis of differentially expressed genes involved in human developmental chondrogenesis

Osteoarthritis (OA), also known as degenerative arthritis, affects millions of people all over the world. OA occurs when the cartilage wears down over time, which is a worldwide complaint. The aim of this study was to screen and verify hub genes involved in developmental chondrogenesis as well as to explore potential molecular mechanisms.The expression profiles of GSE51812 were downloaded from the Gene Expression Omnibus (GEO) database, which contained 9 samples, including 6-week pre-chondrocytes (PC, 6 independent specimens) and 17-week fetal periarticular resting chondrocytes (RC, 3 independent specimens). The raw data were integrated to obtain differentially expressed genes (DEGs) and were further analyzed with bioinformatics analysis. The Gene Ontology (GO) and pathway enrichment of DEGs were conducted via Database for Annotation, Visualization, and Integrated Discovery (DAVID). The protein-protein interaction (PPI) networks of the DEGs were constructed based on data from the search tool for the retrieval of interacting genes (STRING) database. An intersection figure was provided to show the relationship between the DEGs identified in this study and genes from any existed related studies.A total of 9486 DEGs, including 4821 upregulated genes and 4665 downregulated genes were observed. The top 30 developmental chondrogenesis associated genes were identified, including matrix metalloproteinase (MMP)1, MMP3, MMP13, prostaglandin-endoperoxide synthase 2 (PTGS2), and so on. The majority of DEGs, including PTGS2, CCL20, CHI3L1, LIF, CXCL8, and CXCL12 were intensively enriched in immune-associated biological process terms, including inflammatory, and immune responses. Additionally, the majority of DEGs were mainly enriched in NF-kappa β (NF-kβ) signaling pathway and tumor necrosis factor (TNF) signaling pathway. The hub genes identified in STRING and Cytoscape databases included MMP1, MMP3, MMP13, PTGS2 and so on. Among the top 30 upregulated and downregulated DEGs, there were 15 genes have been reported to be associated with OA or developmental chondrogenesis.This large scale gene expression study observed genes associated with human developmental chondrogenesis and their relative GO function, which may offer opportunities for the research for cartilage tissue engineering and novel insights into the prevention of OA in the near future.

Common gene variants interactions related to uric acid transport are associated with knee osteoarthritis susceptibility

BACKGROUND

The presence of genetic variants in uric acid (UA) transporters can be associated with hyperuricemia, and therefore with an increased risk of monosodium urate (MSU) crystal precipitation. The inflammatory process triggered by these crystals leads to cartilage damage, which, in turn, could promote knee osteoarthritis (KOA).

OBJECTIVE

To determine whether genetic polymorphisms of the UA transporters and their interactions are associated with KOA.

MATERIALS AND METHODS

Two hundred forty-three unrelated Mexican-mestizo individuals were recruited for this case-control study. Ninety-three of them were KOA patients but without gout, and one hundred and fifty healthy individuals with no symptoms or signs of KOA were recruited as controls. Forty-one single-nucleotide polymorphisms (SNPs) involved in the UA transporters were genotyped with OpenArray technology in a QuantStudio 12K flex-System with both cases and controls.

RESULTS

After adjusting by age, gender, BMI, and ancestry, significant associations were found for eight SNPs: rs1260326 (GCKR), rs780093 (GCKR), rs17050272 (INHBB), rs1471633 (PDZK1), rs12129861 (PDZK1), rs7193778 (IGF1R), rs17786744 (STC1), and rs1106766 (R3HDM2). With respect to gene-gene interactions, the pairwise interactions of rs112129861 (PDZK1) and rs7193778 (IGF1R); rs17050272 (INHBB) and rs1106766 (R3HDM2); rs1106766 (R3HDM2) and rs780093 (GCKR); rs1260326 (GCKR) and rs17786744 (STC1); and rs17786744 (STC1) and rs1106766 (R3HDM2) make it possible to visualize the synergistic or antagonistic effect of their genotypes or alleles on KOA development.

CONCLUSIONS

Our preliminary results show that the common gene variants related to UA transport are associated with KOA in the Mexican population. Further studies must be carried out to corroborate it.

Transcriptomic and proteomic analysis of iris tissue and aqueous humor in juvenile idiopathic arthritis-associated uveitis

Gene and protein expression profiles of iris biopsies, aqueous humor (AqH), and sera in patients with juvenile idiopathic arthritis-associated uveitis (JIAU) in comparison to control patients with primary open-angle glaucoma (POAG) and HLA-B27-positive acute anterior uveitis (AAU) were investigated. Via RNA Sequencing (RNA-Seq) and mass spectrometry-based protein expression analyses 136 genes and 56 proteins could be identified as being significantly differentially expressed (DE) between the JIAU and POAG group. Gene expression of different immunoglobulin (Ig) components as well as of the B cell-associated factors ID3, ID1, and EBF1 was significantly upregulated in the JIAU group as compared to POAG patients. qRT-PCR analysis showed a significantly higher gene expression of the B cell-related genes CD19, CD20, CD27, CD138, and MZB1 in the JIAU group. At the protein level, a significantly higher expression of Ig components in JIAU than in POAG was confirmed. The B cell-associated protein MZB1 showed a higher expression in JIAU patients than in POAG which was confirmed by western blot analysis. Using bead-based immunoassay analysis we were able to detect a significantly higher concentration of the B cell-activating and survival factors BAFF, APRIL, and IL-6 in the AqH of JIAU and AAU patients than in POAG patients. The intraocularly upregulated B cell-specific genes and proteins in iris tissue suggest that B cells participate in the immunopathology of JIAU. The intracameral environment in JIAU may facilitate local effector and survival functions of B cells, leading to disease course typical for anterior uveitis.

Paeoniflorin inhibits Rho kinase activation in joint synovial tissues of rats with collagen-induced rheumatoid arthritis

Paeoniflorin (PF) has many effects, such as anti-inflammation, immune-regulation, abirritation, and so on. However, the protective mechanisms of PF on rheumatoid arthritis (RA) was not completely known. Thus, we explored deeply the protective mechanisms in a collagen-induced RA (CIA) rat model. CIA was induced in rats by intradermal injection of bovine type II collagen in complete Freund's adjuvant. Later, the CIA rats received oral administration of PF (50 and 100 mg/kg) once a day from the day 21, with the treatment lasting for 14 days. A variety of indicators were measured for evaluation of anti-rheumatism effect, including paw swelling, arthritis scores, and histopathological changes. And the contents of pro-inflammatory cytokines, including tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β), and interleukin-6 (IL-6) in the serum, as well as p-NF-κB p65 and p-MYPT1 in the joint synovial tissues were detected to explore the possible mechanisms. The results demonstrated that PF treatment significantly ameliorated the symptoms in CIA rats, reduced the levels of pro-inflammatory cytokines and paw swelling, down-regulated the expressions of p-NF-κB p65 and p-MYPT1. The present results revealed that PF could effectively improve collagen-induced RA in rats by inhibiting Rho kinase activation in the joint synovial tissues, in turn down-regulating expression of p-NF-κB p65 and reducing contents of pro-inflammatory cytokines. Moreover, PF may be an effective agent for RA.

Identification of gene expression profiles and key genes in subchondral bone of osteoarthritis using weighted gene coexpression network analysis

Osteoarthritis (OA) significantly influences the quality life of people around the world. It is urgent to find an effective way to understand the genetic etiology of OA. We used weighted gene coexpression network analysis (WGCNA) to explore the key genes involved in the subchondral bone pathological process of OA. Fifty gene expression profiles of GSE51588 were downloaded from the Gene Expression Omnibus database. The OA-associated genes and gene ontologies were acquired from JuniorDoc. Weighted gene coexpression network analysis was used to find disease-related networks based on 21756 gene expression correlation coefficients, hub-genes with the highest connectivity in each module were selected, and the correlation between module eigengene and clinical traits was calculated. The genes in the traits-related gene coexpression modules were subject to functional annotation and pathway enrichment analysis using ClusterProfiler. A total of 73 gene modules were identified, of which, 12 modules were found with high connectivity with clinical traits. Five modules were found with enriched OA-associated genes. Moreover, 310 OA-associated genes were found, and 34 of them were among hub-genes in each module. Consequently, enrichment results indicated some key metabolic pathways, such as extracellular matrix (ECM)-receptor interaction (hsa04512), focal adhesion (hsa04510), the phosphatidylinositol 3'-kinase (PI3K)-Akt signaling pathway (PI3K-AKT) (hsa04151), transforming growth factor beta pathway, and Wnt pathway. We intended to identify some core genes, collagen (COL)6A3, COL6A1, ITGA11, BAMBI, and HCK, which could influence downstream signaling pathways once they were activated. In this study, we identified important genes within key coexpression modules, which associate with a pathological process of subchondral bone in OA. Functional analysis results could provide important information to understand the mechanism of OA.

Photobiomodulation therapy associated with treadmill training in the oxidative stress in a collagen-induced arthritis model

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by chronic and systemic inflammation, which leads to the destruction of the cartilage and bone and affects tissues in multiple joints. Oxidative stress has been implicated with regards to involvement in various disease conditions, such as diabetes mellitus and neurodegenerative, respiratory, cardiovascular, and RA diseases. In vivo experimental studies using photobiomodulation therapy (PBMT) have shown positive effects in reducing lipid peroxidation and in increasing antioxidant activity. The regular practice of physical exercise has also been reported to be a beneficial treatment capable of reducing oxidative damage. Thus, the aim of this study was to analyze the effects of photobiomodulation therapy at 2- and 4-J doses associated with physical exercise on oxidative stress in an experimental model of RA in protein expression involving superoxide dismutase (SOD), glutathione peroxidase (GPX), and/or catalase (CAT) on thiobarbituric acid reactive substances (TBARS). In this study, 24 male Wistar rats divided into four groups were submitted to an RA model (i.e., collagen-induced arthritis, CIA), with the first immunization performed at the base of the tail on days 0 and 7 were included. After 28 days, a third intraarticular dose was administered in both knees of the animals. After the last induction, PBMT was started immediately, transcutaneously at two points (i.e., the medial and lateral), with a total of 15 applications. Treadmill exercise was also started the day after the last induction, and lasted for 5 weeks. With respect to results, we obtained the decreases in the lipid peroxidation and the increases of the antioxidant activities of SOD, GPX and CAT, with physical exercise associated to PBMT in doses of 2 and 4 J. In conclusion, physical exercise associated with PBMT decreases lipid peroxidation and increases antioxidant activity.

Screening of gene signatures for rheumatoid arthritis and osteoarthritis based on bioinformatics analysis

The current study aimed to identify gene signatures during rheumatoid arthritis (RA) and osteoarthritis (OA), and used these to elucidate the underlying modular mechanisms. Using the Gene Expression Omnibus database, the present study obtained the GSE7669 mRNA expression microarray data from RA and OA synovial fibroblasts (n=6 each). The differentially expressed genes (DEGs) in RA synovial samples compared with OA samples were identified using the Linear Models for Microarray Analysis package. The Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were performed using the Database for Annotation Visualization and Integrated Discovery. A protein‑protein interaction network was constructed and the modules were further analyzed using the Molecular Complex Detection plugin of Cytoscape. A total of 181 DEGs were identified by comparing RA and OA synovial samples (96 up‑ and 85 downregulated genes). The significant DEGs in module 1, including collagen, type I, α 1 (COL1A1), COL3A1, COL4A1 and COL11A1, were predominantly enriched in the extracellular matrix (ECM)‑receptor interaction and focal adhesion pathways. Additionally, significant DEGs in module 2, including radical S‑adenosyl methionine domain containing 2 (RSAD2), 2'‑5'‑oligoadenylate synthetase 2 (OAS2), myxovirus (influenza virus) resistance 1 (MX1) and ISG15 ubiquitin‑like modifier (ISG15), were predominantly associated with immune function pathways. In conclusion, the present study indicated that RSAD2, OAS2, MX1 and ISG15 may be notable gene signatures in RA development via regulation of the immune response. COL3A1, COL4A1, COL1A1 and COL11A1 may be important gene signatures in OA development via involvement in the pathways of ECM-receptor interactions and focal adhesions.

Paeoniflorin ameliorates rheumatoid arthritis in rat models through oxidative stress, inflammation and cyclooxygenase 2

Paeoniflorin has anti-inflammatory, anti-allergy, immune regulatory and pain-relieving effects, amongst other roles. However, the mechanisms underlying the protective effects of paeoniflorin on rheumatoid arthritis (RA) remain under investigation; the objective of the current study was to evaluate these protective effects in the context of an RA model. Rats were randomly divided into 5 groups, as follows: The control group, the RA rat model group, and the paeoniflorin groups, in which paeoniflorin was administered at concentrations of 5, 10 and 20 mg/kg for 3 weeks. The pain thresholds and arthritic symptoms of the RA rats were measured. Oxidative stress and inflammatory cytokines were also analyzed and western blot analysis was used to evaluate cyclooxygenase-2 (COX-2) protein expression levels. Paeoniflorin significantly increased the pain threshold and decreased the arthritic symptoms in the RA rat model. Notably, paeoniflorin reduced the malondialdehyde concentration and increased the activity of superoxide dismutase, catalase and glutathione peroxidase. Furthermore, paeoniflorin attenuated the activity of nuclear factor-κB p65 unit, tumor necrosis factor-α, interleukin (IL)-1β and IL-6, and reduced the COX-2 protein expression level. The present study indicates that paeoniflorin ameliorates disease in rat models of RA through oxidative stress, inflammation and alterations to COX-2 expression.