Accelerated biological aging as a potential risk factor for rheumatoid arthritis.

OBJECTS: Previous studies have suggested a potential correlation between rheumatoid arthritis (RA) and biological aging, but the intricate connections and mechanisms remain elusive. METHODS: In our study, we focused on two specific measures of biological age (PhenoAge and BioAge), which are derived from clinical biomarkers. The residuals of these measures, when compared to chronological age, are defined as biological age accelerations (BAAs). Utilizing the extensive UK Biobank dataset along with various genetic datasets, we conducted a thorough assessment of the relationship between BAAs and RA at both the individual and aggregate levels. RESULTS: Our observational studies revealed positive correlations between the two BAAs and the risk of developing both RA and seropositive RA. Furthermore, the genetic risk score (GRS) for PhenoAgeAccel was associated with an increased risk of RA and seropositive RA. Linkage disequilibrium score regression (LDSC) analysis further supported these findings, revealing a positive genetic correlation between PhenoAgeAccel and RA. PLACO analysis identified 38 lead pleiotropic single nucleotide polymorphisms linked to 301 genes, providing valuable insights into the potential mechanisms connecting PhenoAgeAccel and RA. CONCLUSION: In summary, our study has successfully revealed a positive correlation between accelerated biological aging, as measured by BAAs, and the susceptibility to RA.

Autoimmune diseases and their genetic link to bronchiectasis: insights from a genetic correlation and Mendelian randomization study.

Background: Previous studies have demonstrated that autoimmune diseases are closely associated with bronchiectasis (BE). However, the causal effects between autoimmune diseases and BE remain elusive. Methods: All summary-level data were obtained from large-scale Genome-Wide Association Studies (GWAS). The univariate Mendelian randomization (UVMR) was utilized to investigate the genetic causal correlation (rg) of 12 autoimmune diseases and bronchiectasis, The Multivariable Mendelian Randomization (MVMR) method was used to explore the effects of the confounding factors. Further investigation was conducted to identify potential intermediate factors using mediation analysis. Finally, the linkage disequilibrium score regression (LDSC) method was used to identify genetic correlations among complex traits. A series of sensitivity analyses was performed to validate the robustness of the results. Results: The LDSC analysis revealed significant genetic correlations between BE and Crohn's disease (CD) (rg = 0.220, P = 0.037), rheumatoid arthritis (RA) (rg = 0.210, P = 0.021), and ulcerative colitis (UC) (rg = 0.247, P = 0.023). However, no genetic correlation was found with other autoimmune diseases (P > 0.05). The results of the primary IVW analysis suggested that for every SD increase in RA, there was a 10.3% increase in the incidence of BE (odds ratio [OR] = 1.103, 95% confidence interval [CI] 1.055-1.154, P = 1.75×10-5, FDR = 5.25×10-5). Furthermore, for every standard deviation (SD) increase in celiac disease (CeD), the incidence of BE reduced by 5.1% (OR = 0.949, 95% CI 0.902-0.999, P = 0.044, FDR = 0.044). We also observed suggestive evidence corresponding to a 3% increase in BE incidence with T1DM (OR = 1.033, 95% CI 1.001-1.066, P = 0.042, FDR = 0.063). Furthermore, MVMR analysis showed that RA was an independent risk factor for BE, whereas mediator MR analysis did not identify any mediating factors. The sensitivity analyses corroborated the robustness of these findings. Conclusion: LDSC analysis revealed significant genetic correlations between several autoimmune diseases and BE, and further MVMR analysis showed that RA is an independent risk factor for BE.

Unveiling the link between lactate metabolism and rheumatoid arthritis through integration of bioinformatics and machine learning.

Rheumatoid arthritis (RA) is a persistent autoimmune condition characterized by synovitis and joint damage. Recent findings suggest a potential link to abnormal lactate metabolism. This study aims to identify lactate metabolism-related genes (LMRGs) in RA and investigate their correlation with the molecular mechanisms of RA immunity. Data on the gene expression profiles of RA synovial tissue samples were acquired from the gene expression omnibus (GEO) database. The RA database was acquired by obtaining the common LMRDEGs, and selecting the gene collection through an SVM model. Conducting the functional enrichment analysis, followed by immuno-infiltration analysis and protein-protein interaction networks. The results revealed that as possible markers associated with lactate metabolism in RA, KCNN4 and SLC25A4 may be involved in regulating macrophage function in the immune response to RA, whereas GATA2 is involved in the immune mechanism of DC cells. In conclusion, this study utilized bioinformatics analysis and machine learning to identify biomarkers associated with lactate metabolism in RA and examined their relationship with immune cell infiltration. These findings offer novel perspectives on potential diagnostic and therapeutic targets for RA.

Macrophage-derived mir-100-5p orchestrates synovial proliferation and inflammation in rheumatoid arthritis through mTOR signaling.

BACKGROUND: Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by synovial inflammation, causing substantial disability and reducing life quality. While macrophages are widely appreciated as a master regulator in the inflammatory response of RA, the precise mechanisms underlying the regulation of proliferation and inflammation in RA-derived fibroblast-like synoviocytes (RA-FLS) remain elusive. Here, we provide extensive evidence to demonstrate that macrophage contributes to RA microenvironment remodeling by extracellular vesicles (sEVs) and downstream miR-100-5p/ mammalian target of rapamycin (mTOR) axis. RESULTS: We showed that bone marrow derived macrophage (BMDM) derived-sEVs (BMDM-sEVs) from collagen-induced arthritis (CIA) mice (cBMDM-sEVs) exhibited a notable increase in abundance compared with BMDM-sEVs from normal mice (nBMDM-sEVs). cBMDM-sEVs induced significant RA-FLS proliferation and potent inflammatory responses. Mechanistically, decreased levels of miR-100-5p were detected in cBMDM-sEVs compared with nBMDM-sEVs. miR-100-5p overexpression ameliorated RA-FLS proliferation and inflammation by targeting the mTOR pathway. Partial attenuation of the inflammatory effects induced by cBMDM-sEVs on RA-FLS was achieved through the introduction of an overexpression of miR-100-5p. CONCLUSIONS: Our work reveals the critical role of macrophages in exacerbating RA by facilitating the transfer of miR-100-5p-deficient sEVs to RA-FLS, and sheds light on novel disease mechanisms and provides potential therapeutic targets for RA interventions.

Abatacept increases T cell exhaustion in early RA individuals who carry HLA risk alleles.

Exhausted CD8 T cells (TEX) are associated with worse outcome in cancer yet better outcome in autoimmunity. Building on our past findings of increased TIGIT+KLRG1+ TEX with teplizumab therapy in type 1 diabetes (T1D), in the absence of treatment we found that the frequency of TIGIT+KLRG1+ TEX is stable within an individual but differs across individuals in both T1D and healthy control (HC) cohorts. This TIGIT+KLRG1+ CD8 TEX population shares an exhaustion-associated EOMES gene signature in HC, T1D, rheumatoid arthritis (RA), and cancer subjects, expresses multiple inhibitory receptors, and is hyporesponsive in vitro, together suggesting co-expression of TIGIT and KLRG1 may broadly define human peripheral exhausted cells. In HC and RA subjects, lower levels of EOMES transcriptional modules and frequency of TIGIT+KLRG1+ TEX were associated with RA HLA risk alleles (DR0401, 0404, 0405, 0408, 1001) even when considering disease status and cytomegalovirus (CMV) seropositivity. Moreover, the frequency of TIGIT+KLRG1+ TEX was significantly increased in RA HLA risk but not non-risk subjects treated with abatacept (CTLA4Ig). The DR4 association and selective modulation with abatacept suggests that therapeutic modulation of TEX may be more effective in DR4 subjects and TEX may be indirectly influenced by cellular interactions that are blocked by abatacept.

Exploring the Correlation between Interleukin-17A Promoter Polymorphism at its -197 G/A and Rheumatoid Arthritis: Impact on Disease Severity and Activity.

T helper 17 (Th17) cells have been reported to be the most powerful factor in autoimmune disorder pathogenesis, which points to the Th17 master cytokine, interleukin (IL)-17A, as the crucial mediator. We aimed to determine the impact of IL-17A polymorphism in the -197 G/A promoter region on level of IL-17 and intensity of rheumatoid arthritis (RA) disease symptoms. This case-control study was conducted at the Department of Clinical Rheumatology of Aswan university Hospital and included 35 people suffering RA and 30 volunteer controls, matched for age and sex. Rheumatoid factor (RF), anti-cyclic citrullinated peptide (anti-CCP) antibodies, erythrocyte sedimentation rate (ESR), serum IL-17, and C-reactive protein (CRP) were measured in the RA patient group. Restriction fragment length polymorphism (RFLP) was conducted by polymerase chain reaction (PCR) amplicon obtained by IL-17A -197 G /A primers. Of the 35 RA patients, RF was positive in 33 (94.29%) and anti-CCP antibodies in 25 (71.43%), CRP in 31 (88.57%). Of the 35 RA patients, 5 (14.29%) patients carried the G/G genotype, 18 (51.43%) G/A and 12 (34.29%) A/A. IL-17 serum level was significantly greater in the more active RA (DAS28 >5.1) group than the less active (DAS28 ≤5.1) group. Of the RA patients carrying wild type G/G genotype, 60% had more active disease (DAS 28> 5.1), as compared to those with lower activity (DAS 28 ≤5.1), 40% carried the wild type G/G genotype. In conclusion, the study findings imply that IL-17A gene polymorphism is connected to RA clinical severity rather than with RA susceptibility.

[Mechanism of bulleyaconitine A in inhibiting bone destruction of rheumatoid arthritis via Src/PI3K/Akt signaling pathway].

Based on the sarcoma receptor coactivator(Src)/phosphatidylinositol 3-kinase(PI3K)/protein kinase B(Akt) signaling pathway, the mechanism of action of bulleyaconitine A in the treatment of bone destruction of experimental rheumatoid arthritis(RA) was explored. Firstly, key targets of RA bone destruction were collected through GeneCards, PharmGKB, and OMIM databa-ses. Potential targets of bulleyaconitine A were collected using SwissTargetPrediction and PharmMapper databases. Next, intersection targets were obtained by the Venny 2.1.0 platform. Protein-protein interaction(PPI) network and topology analysis were managed by utilizing the STRING database and Cytoscape 3.8.0. Then, Gene Ontology(GO) and Kyoto Encyclopedia of Genes and Genomes(KEGG) enrichment analyses were conducted in the DAVID database. AutoDock Vina was applied to predict the molecular docking and binding ability of bulleyaconitine A with key targets. Finally, a receptor activator of nuclear factor-κB(RANKL)-induced osteoclast differentiation model was established in vitro. Quantitative real-time polymerase chain reaction(qRT-PCR) was used to detect the mRNA expression levels of related targets, and immunofluorescence and Western blot were adopted to detect the protein expression level of key targets. It displayed that there was a total of 29 drug-disease targets, and Src was the core target of bulleyaconitine A in anti-RA bone destruction. Furthermore, KEGG enrichment analysis revealed that bulleyaconitine A may exert an anti-RA bone destruction effect by regulating the Src/PI3K/Akt signaling pathway. The molecular docking results showed that bulleyaconitine A had better bin-ding ability with Src, phosphatidylinositol-4,5-diphosphate 3-kinase(PIK3CA), and Akt1. The result of the experiment indicated that bulleyaconitine A not only dose-dependently inhibited the mRNA expression levels of osteoclast differentiation-related genes cathepsin K(CTSK) and matrix metalloproteinase-9(MMP-9)(P<0.01), but also significantly reduced the expression of p-c-Src, PI3K, as well as p-Akt in vitro osteoclasts(P<0.01). In summary, bulleyaconitine A may inhibit RA bone destruction by regulating the Src/PI3K/Akt signaling pathway. This study provides experimental support for the treatment of RA bone destruction with bulleyaconitine A and lays a foundation for the clinical application of bulleyaconitine A.

[Mechanism of Yuxuebi Tablets in treating synovial inflammation in rheumatoid arthritis based on transcriptomics].

This study investigated the mechanism of Yuxuebi Tablets(YXB) in the treatment of synovial inflammation in rheumatoid arthritis(RA) based on transcriptomic analysis. Transcriptome sequencing technology was employed to analyze the gene expression profiles of joint tissues from normal rats, collagen-induced arthritis(CIA) rats(an RA model), and YXB-treated rats. Common diffe-rentially expressed genes(DEGs) were subjected to Gene Ontology(GO) and Kyoto Encyclopedia of Genes and Genomes(KEGG) enrichment analyses. RA synovial inflammation-related target genes were retrieved from the OMIM and GeneCards databases. Venny 2.1 software was used to identify the intersection of YXB target genes and RA synovial inflammation-related target genes, and GO and KEGG enrichment analyses were performed on the intersecting target genes. Immunohistochemistry was used to assess the protein expression levels of the inflammatory factors interleukin-1ß(IL-1ß) and tumor necrosis factor-α(TNF-α) in rat joint tissues. Western blot analysis was employed to measure the expression levels of key proteins in the phosphatidylinositol 3-kinase(PI3K)/protein kinase B(Akt) signaling pathway. A total of 2 058 DEGs were identified by intersecting the genes from the normal group vs model group and the model group vs YXB treatment group. A search in OMIM and GeneCards databases yielded 1 102 RA synovial inflammation-related target genes. After intersecting with the DEGs in the YXB treatment group, 204 intersecting target genes were identified, primarily involving biological processes such as immune response, signal transduction, and inflammatory response; cellular components including plasma membrane, extracellular space, and extracellular region; molecular functions like protein binding, identical protein binding, and receptor binding. These target genes were mainly enriched in signaling pathways such as PI3K/Akt, cytokine-cytokine receptor interaction, and Janus kinase/signal transducer and activator of transcription(JAK/STAT). Western blot results showed that YXB at low, medium, and high doses could significantly inhibit the expression levels of key proteins in the PI3K/Akt signaling pathway in rat joint tissues in a dose-dependent manner. Immunohistochemistry further confirmed these findings, showing that YXB not only suppressed the protein expression levels of the inflammatory factors IL-1ß and TNF-α in the joint synovial tissues of CIA rats, but also inhibited p-Akt protein expression. In conclusion, this study used transcriptomic analysis to uncover the key mechanisms of YXB in inhibiting synovial inflammation and alleviating the progression of RA, with a focus on its role in suppressing the PI3K/Akt signaling pathway.

[Mechanism of aqueous extract of Strychni Semen in improving pain in rats with rheumatoid arthritis based on TLR4/TNF-α/MMP-9 signaling pathway].

This study aims to explore the mechanism of aqueous extract of Strychni Semen(SA) in relieving pain in the rat model of rheumatoid arthritis(RA) via Toll-like receptor 4(TLR4)/tumor necrosis factor-α(TNF-α)/matrix metalloproteinase-9(MMP-9) signaling pathway. Firstly, the main chemical components of Strychni Semen were searched against TCMSP, TCMID, ETCM, and related literature, and the main targets of the chemical components were retrieved from TargetNet and SwissTargetPrediction. The main targets of RA and pain were searched against GeneCards, Online Mendelian Inheritance in Man(OMIM), and Therapeutic Target Database(TTD). Venny 2.1.0 was used to obtain the common targets shared by Strychni Semen, RA, and pain, and STRING and Cytoscape 3.6.1 were used to build the protein-protein interaction network. Then, molecular docking was carried out in AutoDock Vina. Finally, the rat model of type Ⅱ collagen-induced arthritis(CIA) was established. The up-down method and acetone method were employed to examine the mechanical pain threshold and cold pain threshold of rats, and the pain-relieving effect of SA on CIA rats was evaluated comprehensively. Hematoxylin-eosin(HE) staining was employed to evaluate the histopathological changes of joints in CIA rats. The expression levels of key target proteins was determined by immunohistochemistry and Western blot, and the mRNA levels of key targets were determined by real-time fluorescence quantitative polymerase chain reaction(real-time PCR). The results of network prediction showed that Strychni Semen may act on the TLR4/TNF-α/MMP-9 signaling pathway to exert the pain-relieving effect. The results of molecular docking showed that brucine, the main active component of SA, had strong binding ability to TLR4, TNF-α, and MMP-9. The results of animal experiments showed that SA improved the mechanical and cold pain sensitivity(P<0.05, P<0.01) and reduced the joint histopathological score of CIA rats(P<0.01). In addition, medium and high doses of SA down-regulated the protein and mRNA levels of TNF-α, TLR4, and MMP-9(P<0.05,P<0.01). In conclusion, SA alleviated the mechanical pain sensitivity, cold pain sensitivity, and joint histopathological changes in CIA rats by inhibiting the over activation of TLR4/TNF-α/MMP-9 signaling pathway.

A bibliometric analysis of miRNAs in rheumatoid arthritis from 2001 to 2022: Research hotspots and trends.

BACKGROUND: MicroRNAs (miRNAs) are widely recognized in the pathogenesis of autoimmune disease. As a key regulatory factor, miRNAs have introduced new biomarkers for the early diagnosis of rheumatoid arthritis (RA) and provided a favorable research direction for the development of novel therapeutic targets. This study aimed to explore the hotspots of miRNA research related to RA published from different countries, organizations, and authors. METHODS: From 2001 to 2022, publications on miRNA related to RA were identified in the Web of Science database. The total and annual number of publishments, citations, impact factor, H-index, productive authors, and involved journals were collected for quantitative and qualitative comparisons. RESULTS: A total of 29 countries/regions in the world have participated in the research of miRNAs and RA over the past two decades, and China (760, 53.18%) and the United States (233, 16.31%) account for the majority of the total publications. China dominated in total citation (17881) and H-index (62). A total of 507 academic journals have published articles in related fields, and Frontiers in Immunology published the most (53, 3.71%). Chih-hsin Tang of the China Medical University has published the most papers (16, 1.2%). Stanczyk (2008) published the most cited article Altered expression of miRNAs in synovial fibroblasts and synovial tissue in rheumatoid arthritis in Arthritis and Rheumatism, with 660 citations. Inflammation is the high-frequency keyword outside of RA and miRNAs, and related researches have mainly focused on miR-146a and miR-155. CONCLUSIONS: In the past two decades, extensive and continuous research has been conducted to investigate the role of miRNAs in RA, and miRNAs are widely recognized in the pathogenesis of RA. Related research has mainly focused on miR-146a and miR-155 that have shown promising results as key factors in RA experimental models. Focusing on clinical applications and translational research may be the future research direction and hotspot based on molecular biology basic research and mechanism exploration.

Fibroblast expression of neurotransmitter receptor HTR2A associates with inflammation in rheumatoid arthritis joint.

The study of neuroimmune crosstalk and the involvement of neurotransmitters in inflammation and bone health has illustrated their significance in joint-related conditions. One important mode of cell-to-cell communication in the synovial fluid (SF) is through extracellular vesicles (EVs) carrying microRNAs (miRNAs). The role of neurotransmitter receptors in the pathogenesis of inflammatory joint diseases, and whether there are specific miRNAs regulating differentially expressed HTR2A, contributing to the inflammatory processes and bone metabolism is unclear. Expression of neurotransmitter receptors and their correlated inflammatory molecules were identified in rheumatoid arthritis (RA) and osteoarthritis (OA) synovium from a scRNA-seq dataset. Immunohistochemistry staining of synovial tissue (ST) from RA and OA patients was performed for validation. Expression of miRNAs targeting HTR2A carried by SF EVs was screened in low- and high-grade inflammation RA from a public dataset and validated by qPCR. HTR2A reduction by target miRNAs was verified by miRNAs mimics transfection into RA fibroblasts. HTR2A was found to be highly expressed in fibroblasts derived from RA synovial tissue. Its expression showed a positive correlation with the degree of inflammation observed. 5 miRNAs targeting HTR2A were decreased in RA SF EVs compared to OA, three of which, miR-214-3p, miR-3120-5p and miR-615-3p, mainly derived from monocytes in the SF, were validated as regulators of HTR2A expression. The findings suggest that fibroblast HTR2A may play a contributory role in inflammation and the pathogenesis of RA. Additionally, targeting miRNAs that act upon HTR2A could present novel therapeutic strategies for alleviating inflammation in RA.

A novel diagnostic model based on lncRNA PTPRE expression, neutrophil count and red blood cell distribution width for diagnosis of seronegative rheumatoid arthritis.

Diagnosis of seronegative rheumatoid arthritis (SNRA) is difficult due to the lack of diagnostic markers. The study aims to construct a novel diagnostic model based on long noncoding RNAs (lncRNAs) expression and laboratory indicators to provide a new idea for diagnostic methods of SNRA. Differentially expressed lncRNAs in peripheral blood cells of RA patients were screened through eukaryotic long noncoding RNA sequencing and validated by quantitative real-time PCR. Meanwhile, the correlation between lncRNAs expression and laboratory indicators was analyzed. The diagnostic value was evaluated by receiver operating characteristic curve analysis. Finally, combined with laboratory indicators, a diagnostic model for SNRA was constructed based on logistic regression and visualized by nomogram. Expression of ADGRE5, FAM157A, PTPN6 and PTPRE in peripheral blood was significantly increased in RA than healthy donors. Meanwhile, we analyzed the relationship between lncRNAs and erythrocyte sedimentation rate, C-reactive protein and CD4 + T cell-related cytokines and transcription factors. Results showed that FAM157A and PTPN6 were positively related to RORγt, and negatively related to GATA3. Moreover, PTPRE has potential discrimination ability between SNRA and healthy donor (AUC = 0.6709). Finally, we constructed a diagnostic model based on PTPRE, neutrophil count and red blood cell distribution width (RDW). The AUC of the model was 0.939 and well-fitted calibration curves. Decision curve analysis indicated the model had better predict performance in SNRA diagnosis. Our study constructed a novel diagnostic model based on PTPRE, neutrophil count and RDW which may serve as a potential tool for the diagnosis of SNRA.

TNF-α signals through ITK-Akt-mTOR to drive CD4+ T cell metabolic reprogramming, which is dysregulated in rheumatoid arthritis.

Upon activation, T cells undergo metabolic reprogramming to meet the bioenergetic demands of clonal expansion and effector function. Because dysregulated T cell cytokine production and metabolic phenotypes coexist in chronic inflammatory disease, including rheumatoid arthritis (RA), we investigated whether inflammatory cytokines released by differentiating T cells amplified their metabolic changes. We found that tumor necrosis factor-α (TNF-α) released by human naïve CD4+ T cells upon activation stimulated the expression of a metabolic transcriptome and increased glycolysis, amino acid uptake, mitochondrial oxidation of glutamine, and mitochondrial biogenesis. The effects of TNF-α were mediated by activation of Akt-mTOR signaling by the kinase ITK and did not require the NF-κB pathway. TNF-α stimulated the differentiation of naïve cells into proinflammatory T helper 1 (TH1) and TH17 cells, but not that of regulatory T cells. CD4+ T cells from patients with RA showed increased TNF-α production and consequent Akt phosphorylation upon activation. These cells also exhibited increased mitochondrial mass, particularly within proinflammatory T cell subsets implicated in disease. Together, these findings suggest that T cell-derived TNF-α drives their metabolic reprogramming by promoting signaling through ITK, Akt, and mTOR, which is dysregulated in autoinflammatory disease.

Causal association between rheumatoid arthritis and an increased risk of age-related macular degeneration: A Mendelian randomization study.

This study's goal is to evaluate if there is a causal connection between rheumatoid arthritis (RA) and age-related macular degeneration (AMD), despite past epidemiological studies suggesting an association between the 2 disorders. The impact of RA on AMD is still unknown. Mendelian randomization (MR) was utilized in this study to assess the two-sample causal relationship between RA and AMD. Summary data from GWAS for RA and AMD in individuals with all European ancestries were gathered using the IEU GWAS database. The GWAS summary statistics of RA (14,361 RA patients and 43,923 healthy controls) and AMD (14,034 AMD patients and 91,214 controls participated) were obtained from the IEU GWAS database. After identifying suitable instrumental variables in line with the 3 MR assumptions, we conducted MR using the Mendelian randomization-Egger (MR-Egger), weighted median, and inverse variance weighting techniques. The MR-Egger intercept and MR-Polyvalent Residuals and Outliers methods were used to investigate the effects of horizontal pleiotropy. The leave-one-out strategy was used to prevent bias caused by certain single nucleotide polymorphisms. Sensitivity analysis was used to detect the heterogeneity. Using 50 single nucleotide polymorphisms as instrumental variables, this study examined the relationship between RA and AMD and discovered that RA increased the risk of AMD (inverse variance weighting odds ratio [OR] = 1.056, 95% confidence interval [CI] = 1.02-1.09, P = 5.44E-04; weighted median OR = 1.085, 95% CI = 1.04-1.14, P = 4.05E-04; MR-Egger OR = 1.074, 95% CI = 1.01-1.14, P = 2.18E-2). The current investigation demonstrated a causal link between AMD and RA. RA increased the risk of AMD. It is advised that future research concentrate on the processes underlying the relationship between RA and AMD.

Synovial fibroblast gene expression is associated with sensory nerve growth and pain in rheumatoid arthritis.

It has been presumed that rheumatoid arthritis (RA) joint pain is related to inflammation in the synovium; however, recent studies reveal that pain scores in patients do not correlate with synovial inflammation. We developed a machine-learning approach (graph-based gene expression module identification or GbGMI) to identify an 815-gene expression module associated with pain in synovial biopsy samples from patients with established RA who had limited synovial inflammation at arthroplasty. We then validated this finding in an independent cohort of synovial biopsy samples from patients who had early untreated RA with little inflammation. Single-cell RNA sequencing analyses indicated that most of these 815 genes were most robustly expressed by lining layer synovial fibroblasts. Receptor-ligand interaction analysis predicted cross-talk between human lining layer fibroblasts and human dorsal root ganglion neurons expressing calcitonin gene-related peptide (CGRP+). Both RA synovial fibroblast culture supernatant and netrin-4, which is abundantly expressed by lining fibroblasts and was within the GbGMI-identified pain-associated gene module, increased the branching of pain-sensitive murine CGRP+ dorsal root ganglion neurons in vitro. Imaging of solvent-cleared synovial tissue with little inflammation from humans with RA revealed CGRP+ pain-sensing neurons encasing blood vessels growing into synovial hypertrophic papilla. Together, these findings support a model whereby synovial lining fibroblasts express genes associated with pain that enhance the growth of pain-sensing neurons into regions of synovial hypertrophy in RA.

Identification of PPARG as key gene to link coronary atherosclerosis disease and rheumatoid arthritis via microarray data analysis.

BACKGROUND: Inflammation is the common pathogenesis of coronary atherosclerosis disease (CAD) and rheumatoid arthritis (RA). Although it is established that RA increases the risk of CAD, the underlining mechanism remained indefinite. This study seeks to explore the molecular mechanisms of RA linked CAD and identify potential target gene for early prediction of CAD in RA patients. MATERIALS AND METHODS: The study utilized five raw datasets: GSE55235, GSE55457, GSE12021 for RA patients, and GSE42148 and GSE20680 for CAD patients. Gene Set Enrichment Analysis (GSEA) was used to investigate common signaling pathways associated with RA and CAD. Then, weighted gene co-expression network analysis (WGCNA) was performed on RA and CAD training datasets to identify gene modules related to single-sample GSEA (ssGSEA) scores. Overlapping module genes and differentially expressed genes (DEGs) were considered as co-susceptible genes for both diseases. Three hub genes were screened using a protein-protein interaction (PPI) network analysis via Cytoscape plug-ins. The signaling pathways, immune infiltration, and transcription factors associated with these hub genes were analyzed to explore the underlying mechanism connecting both diseases. Immunohistochemistry and qRT-PCR were conducted to validate the expression of the key candidate gene, PPARG, in macrophages of synovial tissue and arterial walls from RA and CAD patients. RESULTS: The study found that Fc-gamma receptor-mediated endocytosis is a common signaling pathway for both RA and CAD. A total of 25 genes were screened by WGCNA and DEGs, which are involved in inflammation-related ligand-receptor interactions, cytoskeleton, and endocytosis signaling pathways. The principal component analysis(PCA) and support vector machine (SVM) and receiver-operator characteristic (ROC) analysis demonstrate that 25 DEGs can effectively distinguish RA and CAD groups from normal groups. Three hub genes TUBB2A, FKBP5, and PPARG were further identified by the Cytoscape software. Both FKBP5 and PPARG were downregulated in synovial tissue of RA and upregulated in the peripheral blood of CAD patients and differential mRNAexpreesion between normal and disease groups in both diseases were validated by qRT-PCR.Association of PPARG with monocyte was demonstrated across both training and validation datasets in CAD. PPARG expression is observed in control synovial epithelial cells and foamy macrophages of arterial walls, but was decreased in synovial epithelium of RA patients. Its expression in foamy macrophages of atherosclerotic vascular walls exhibits a positive correlation (r = 0.6276, p = 0.0002) with CD68. CONCLUSION: Our findings suggest that PPARG may serve as a potentially predictive marker for CAD in RA patients, which provides new insights into the molecular mechanism underling RA linked CAD.

Characterizing the polygenic overlap and shared loci between rheumatoid arthritis and cardiovascular diseases.

BACKGROUND: Despite substantial research revealing that patients with rheumatoid arthritis (RA) have excessive morbidity and mortality of cardiovascular disease (CVD), the mechanism underlying this association has not been fully known. This study aims to systematically investigate the phenotypic and genetic correlation between RA and CVD. METHODS: Based on UK Biobank, we conducted two cohort studies to evaluate the phenotypic relationships between RA and CVD, including atrial fibrillation (AF), coronary artery disease (CAD), heart failure (HF), and stroke. Next, we used linkage disequilibrium score regression, Local Analysis of [co]Variant Association, and bivariate causal mixture model (MiXeR) methods to examine the genetic correlation and polygenic overlap between RA and CVD, using genome-wide association summary statistics. Furthermore, we explored specific shared genetic loci by conjunctional false discovery rate analysis and association analysis based on subsets. RESULTS: Compared with the general population, RA patients showed a higher incidence of CVD (hazard ratio [HR] = 1.21, 95% confidence interval [CI]: 1.15-1.28). We observed positive genetic correlations of RA with AF and stroke, and a mixture of negative and positive local genetic correlations underlying the global genetic correlation for CAD and HF, with 13 ~ 33% of shared genetic variants for these trait pairs. We further identified 23 pleiotropic loci associated with RA and at least one CVD, including one novel locus (rs7098414, TSPAN14, 10q23.1). Genes mapped to these shared loci were enriched in immune and inflammatory-related pathways, and modifiable risk factors, such as high diastolic blood pressure. CONCLUSIONS: This study revealed the shared genetic architecture of RA and CVD, which may facilitate drug target identification and improved clinical management.

Causal associations between rheumatoid arthritis, cataract and glaucoma in European and East Asian populations: A bidirectional two-sample mendelian randomization study.

BACKGROUND: Previous studies have indicated a heightened susceptibility to cataract and glaucoma among rheumatoid arthritis (RA) patients, while it remains uncertain whether RA is causally associated with cataract and glaucoma. A two-sample mendelian randomization (MR) analysis was used to investigate the causal associations between RA, cataract and glaucoma in European and East Asian populations. METHODS: In the European population, genome-wide association study (GWAS) summary statistics for cataract (372,386 individuals) and glaucoma (377,277 individuals) were obtained from the FinnGen consortium (R9), while RA summary data were derived from a meta-analysis of GWAS encompassing 97173 samples. In the East Asian population, summary data for cataract (212453 individuals), glaucoma (212453 individuals), and RA (22515 individuals) were sourced from the IEU Open GWAS project. Inverse-variance weighted (IVW, random-effects) method served as the primary analysis, complemented by MR‒Egger regression, weighted median, weighted mode and simple mode methods. Additionally, various sensitivity tests, including Cochran's Q test, MR‒Egger intercept, MR pleiotropy Residual Sum and Outlier test and leave-one-out test were performed to detect the heterogeneity, horizontal pleiotropy and stability of the analysis results. RESULTS: Following stringent screening, the number of selected instrumental variables ranged from 8 to 56. The IVW results revealed that RA had an increased risk of cataract (OR = 1.041, 95% CI = 1.019-1.064; P = 2.08×10-4) and glaucoma (OR = 1.029, 95% CI = 1.003-1.057; P = 2.94×10-2) in European populations, and RA displayed a positive association with cataract (OR = 1.021, 95% CI = 1.004-1.039; P = 1.64×10-2) in East Asian populations. Other methods also supported those results by IVW, and sensitivity tests showed that our analysis results were credible and stable. CONCLUSIONS: This study revealed a positive causality between RA and the increased risk of cataract and glaucoma, which provides guidance for the early prevention of cataracts and glaucoma in patients with RA and furnishes evidence for the impact of RA-induced inflammation on ophthalmic diseases.

Seven-chain adaptive immune receptor repertoire analysis in rheumatoid arthritis reveals novel features associated with disease and clinically relevant phenotypes.

BACKGROUND: In rheumatoid arthritis (RA), the activation of T and B cell clones specific for self-antigens leads to the chronic inflammation of the synovium. Here, we perform an in-depth quantitative analysis of the seven chains that comprise the adaptive immune receptor repertoire (AIRR) in RA. RESULTS: In comparison to controls, we show that RA patients have multiple and strong differences in the B cell receptor repertoire including reduced diversity as well as altered isotype, chain, and segment frequencies. We demonstrate that therapeutic tumor necrosis factor inhibition partially restores this alteration but find a profound difference in the underlying biochemical reactivities between responders and non-responders. Combining the AIRR with HLA typing, we identify the specific T cell receptor repertoire associated with disease risk variants. Integrating these features, we further develop a molecular classifier that shows the utility of the AIRR as a diagnostic tool. CONCLUSIONS: Simultaneous sequencing of the seven chains of the human AIRR reveals novel features associated with the disease and clinically relevant phenotypes, including response to therapy. These findings show the unique potential of AIRR to address precision medicine in immune-related diseases.

Integrative analysis and validation of necroptosis-related molecular signature for evaluating diagnosis and immune features in Rheumatoid arthritis.

OBJECTIVES: Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease that is characterized by persistent morning stiffness, joint pain, and swelling. However, there is a lack of reliable diagnostic markers and therapeutic targets that are both effective and trustworthy. METHODS: In this study, gene expression profiles (GSE89408, GSE55235, GSE55457, and GSE77298) were obtained from the Gene Expression Omnibus database. Differentially expressed necroptosis-related genes were attained from intersection of necroptosis-related gene set, differentially expressed genes, and weighted gene co-expression network analysis. The LASSO, random forest, and SVM-RFE machine learning algorithms were utilized to further screen potential diagnostic genes for RA. Immune cell infiltration was analyzed using the CIBERSORT method. The expressions of diagnostic genes were validated through quantitative real-time PCR, western blotting, immunohistochemistry, and immunofluorescence staining in synovial tissues collected from three trauma controls and three RA patients. RESULTS: Five core necroptosis-related genes (FAS, CYBB, TNFSF10, EIF2AK2, and BIRC2) were identified as potential biomarkers for RA. Two different necroptosis patterns based on these five genes were confirmed to significantly correlated with immune cells (especially macrophages). In vitro experiments showed significantly higher mRNA and protein expression levels of CYBB and EIF2AK2 in RA patients compared to normal controls, consistent with the bioinformatics analysis results. CONCLUSION: Our study identified a novel necroptosis-related subtype and five diagnostic biomarkers of RA, revealed vital roles in the development and occurrence of RA, and offered potential targets for clinical diagnosis and immunotherapy.