Rheumatoid Arthritis: Pathogenic Roles of Diverse Immune Cells

Pain in rheumatoid arthritis: Emerging role of high mobility group box 1 protein-HMGB1

Rheumatoid arthritis (RA) is a chronic inflammatory disease where pain, driven by both inflammatory and non-inflammatory processes, is a major concern for patients. This pain can persist even after joint inflammation subsides. High mobility group box-1 (HMGB1) is a non-histone-DNA binding protein located in the nucleus that plays a key role in processes such as DNA transcription, recombination, and replication. HMGB1 can be released into the extracellular space through both passive and active mechanisms. Extracellular HMGB1 contributes to synovial inflammation, bone degradation, and the production of cytokines in RA by binding to toll-like receptors (TLRs) and receptors for advanced glycation end products (RAGE). It also forms complexes with molecules like lipopolysaccharide (LPS) and IL-1β, amplifying inflammatory responses. Due to its central role in these processes, HMGB1 is considered a promising therapeutic target in RA. It also acts as a nociceptive molecule in mediating pain in diseases such as diabetes and bone cancer. In this review, we explore how HMGB1 contributes to chronic pain in RA, supported by both in vitro and in vivo models. We begin by providing an overview of the mechanisms of pain in RA, the structure of HMGB1, its release mechanisms, and the therapeutic potential of targeting HMGB1 in RA. Following this, we highlight its role in peripheral and central pain sensitization through direct activation of the TLR4/MAPK/NF-κB pathway, as well as indirectly through downstream mediators, underscoring its potential as a target for managing RA pain.

Ginsenoside compound K decreases presentation of citrullinated peptides by regulating autophagy-induced autoantigen activation

OBJECTIVE

Citrullinated vimentin (cVIM) triggers the immune response and is the primary autoantigen of rheumatoid arthritis (RA). Ginsenoside compound K (CK), which exerts significant anti-inflammatory effects, was the objective of this study. We aimed to investigate the role and mechanism of CK in regulating presentation of citrullinated peptides.

METHODS

In RA fibroblast-like synoviocytes (RA-FLS), the expression of autoantigen cVIM, antigen presentation-related molecules, autophagy-related proteins, and autophagic flux were investigated. The effect of CK on the antigen presentation capability of FLS was also examined under conditions of autophagy induction and inhibition. Finally, Wistar rats were immunized with cVIM to evaluate the therapeutic effect of CK in an RA model.

RESULTS

In RA-FLS, CK mitigated the expression of cVIM, autophagy-associated proteins, and antigen presentation-related molecules. This regulatory effect was associated with autophagy. cVIM-immunized rats exhibited more severe arthritis and higher levels of anti-CCP antibodies than those with adjuvant- and vimentin (VIM)-induced arthritis. CK significantly alleviated arthritis inflammation in cVIM-immunized rats.

CONCLUSIONS

CK alleviates cVIM-induced arthritis symptoms, with the regulation of autophagy presenting a key cellular event involved in cVIM generation and RA-FLS antigen-presenting ability.

Quality of life, pain, depression, fatigue and sleep in patients with remission or mild fibromyalgia: a comparison with remission or low disease activity rheumatoid arthritis and healthy controls

BACKGROUND

Fibromyalgia is a chronic condition marked by widespread pain and various accompanying symptoms. Compared to healthy individuals and other rheumatic disease patients, it leads to more severe symptoms and a lower quality of life. Whether fibromyalgia patients in a mild activity or remission stage still experience core symptoms remains unclear.

OBJECTIVE

To compare the severity of clinical symptoms and quality of life (QOL) in patients with remission or mild fibromyalgia (RFM) and remission or low disease activity in rheumatoid arthritis (RRA) patients and healthy controls (HCs) to investigate whether fibromyalgia in a stable stage can be disease-free.

METHODS

This cross-sectional study evaluated a total of 266 RFM and 252 RRA patients and 50 HCs using Revised Fibromyalgia Impact Questionnaire (FIQR), Widespread Pain Index (WPI), Pain Visual Analogue Scale (VAS), Numerical Rating Scale, Multidimensional Fatigue Inventory (MFI-20), Pittsburgh Sleep Quality Index (PSQI), and Beck Depression Inventory (BDI), and Short Form-36 Health Status Questionnaire (SF-36).

RESULTS

The FIQR total score and pain VAS, MFI, and PSQI scores were higher in RFM and RRA patients compared to HCs (P < 0.001). RFM patients had higher BDI and WPI scores than RRA patients (P < 0.001). The majority of RFM patients (97.4%) had more than two pain sites, with moderate-to-severe pain (78.2%), sleep disorders (85.0%), and depression (53.4%), all of which were significantly higher than those in RRA patients (P < 0.001). RFM patients also had lower scores in SF-36 physical and mental component summaries and subscores for role physical, pain index, general health perception, vitality, and mental health index, but a higher social functioning score than RRA patients (P < 0.001).

CONCLUSION

Despite being in a mild activity or remission stage, RFM patients experience more severe symptoms and poorer QOL than RRA patients. Therefore, individualized evaluation and intensive management are required.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02449395, registered on May 20, 2015.

Inula viscosa (L). Aiton leaves extract ameliorate arthritis by antioxidative and anti-inflammatory effects in formaldehyde-induced arthritis in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Inula viscosa (L.) Aiton is a traditional medicinal plant widely distributed and used in Mediterranean countries, its leaves are prepared by maceration to treat, rheumatic pain, inflammatory diseases, diabetes, anemia and cancer.

AIM OF THE STUDY

The present study purpose to investigate the anti-inflammatory efficacy of I. viscosa leaves methanol extract (IVME) at three different doses on formaldehyde-induced arthritis in NMRI albinos mice.

MATERIALS AND METHODS

Mice were divided into six groups (n = 6) as follows: normal control, disease control, Diclofenac group (10 mg/kg, p.o. daily) and three groups, daily treated with 50, 100 and 200 mg/kg IVME (p.o.); Formaldehyde models were obtained by a sub-plantar administration of 20 μl of formaldehyde (3.75% v/v) into the right hind paws of NMRI albino mice on 1st and 3rd days of the 10 experimental days. Joint diameter was measured, arthritis severity was evaluated by inhibition of paw edema, histological changes, synovial hyperplasia and immune cells infiltration was evaluated by histological and immunohistochemical analyses of CD3+, CD20+ and CD68+. Post-mitochondrial supernatants (PMS) from liver tissues homogenates were collected for the assessment of enzymatic and non-enzymatic antioxidants: Catalase (CAT) & Myeloperoxidase (MPO) activities, glutathione (GSH) and an oxidative stress biomarker (nitric-oxide (NO)) level.

RESULTS

Administration of I. visocsa (at low dose: 50 mg/kg) significantly (∗∗∗p < 0.001) ameliorated the induced arthritis severity, reduced hyperplasia of synovial membrane, bone erosion and immune cells infiltration (∗p < 0.05), resulted by restoration of paw diameter. It also decreased levels of NO (∗∗∗p < 0.001) and MPO activity (∗∗∗p < 0.001), and significantly restored GSH levels (∗p < 0.05) and CAT activity (∗∗∗p < 0.001) in liver tissues.

CONCLUSION

These findings suggest that I. viscosa leaves have an anti-arthritic property. Which is due to the combination of antioxidant activity regulating oxidative stress and anti-inflammatory effect by probably cytokines regulation.

M3-DPPE Liposomal Nanoparticles Encapsulating CLEC12A Enhance CD206-Mediated Endocytosis and Efficacy in the Collagen-Induced Arthritis Model

OBJECTIVE

This study aimed to investigate the efficacy of M3-DPPE liposomal nanoparticles encapsulated with mRNA encoding cytokines (M3-mRNAs) in targeting macrophages for the treatment of inflammation-induced joint injury.

METHODS

in vitro, M3-mRNAs were administered to peritoneal exudate macrophages (PEMs), and the uptake was assessed using flow cytometry. The mechanism of uptake was investigated by blocking the CLEC12A pathway with M3-SiCLEC12A and observing CD206-mediated endocytosis. In vivo, the distribution of Dir-labeled M3-drugs was monitored using IVIS imaging, and its accumulation in inflammatory and noninflammatory areas was evaluated. The therapeutic potential was evaluated in collagen-induced arthritis (CIA) model mice by assessing macrophage polarization, joint pathology, and cytokine expression.

RESULTS

in vitro studies demonstrated that M3-mRNAs were taken up significantly by PEMs via CD206-mediated endocytosis. In vivo imaging showed that Dir-labeled M3-drugs accumulated predominantly in inflammatory areas and subsequently in bone injury joints. Treatment with M3-drugs in collagen-induced arthritis model mice increased the population of F4/80+ and F4/80+/CD206+ M2 macrophages in inflamed joints, leading to reduced joint fibrosis and modulation of cytokine levels, including decreased pro-inflammatory cytokines (IL-6, IL-1β, TNF-α, and INF-γ) and increased anti-inflammatory cytokines (IL-10 and TGF-β).

CONCLUSIONS

M3-SiCLEC12A enhanced CD206-mediated endocytosis of M3-mRNAs and M3-drugs in macrophages, promoting the production of corresponding proteins and modulating the immune microenvironment. This treatment approach shows promise in repairing inflammation-induced bone and joint injury by balancing pro-inflammatory and anti-inflammatory cytokines. However, further research is required to address drug tolerance and safety concerns and minimize potential side effects before clinical application in autoimmune diseases caused by inflammation.

SLC7A11 suppresses pyroptosis to alleviate rheumatoid arthritis development by modulating the IL-17 pathway

BACKGROUND

Rheumatoid arthritis (RA) is an autoimmune disease of unknown etiology. This study aims to explore the potential mechanisms by which solute carrier family 7 member 11 (SLC7A11) influences RA development.

METHODS

Collagen-induced arthritis (CIA) mice were constructed to observe disease onset and pathological scores. Pathological changes were examined using Hematoxylin-eosin and Safranin O-Fast Green staining. Levels of lactate dehydrogenase (LDH), inflammatory cytokines (tumor necrosis factor [TNF]-α, interleukin [IL]-18 and IL-1β), and oxidative stress (reactive oxygen species, malondialdehyde, and glutathione) were measured using ELISA. Western blotting was performed to detect the expression of pyroptosis- and pathway-related proteins. Fibroblast-like synoviocytes of RA (RA-FLS) were treated with TNF-α. Cell migration, invasion, and Caspase-1 levels were assessed through scratch assays, Transwell assays, and flow cytometry, respectively. The correlation between SLC7A11 and immune cell infiltration in RA was analyzed using bioinformatics. Additionally, downstream pathways of SLC7A11 in RA were screened, and the impacts of SLC7A11 on these pathways were validated in vitro.

RESULTS

CIA mice were successfully established, revealing significant downregulation of SLC7A11 in RA. Staining results indicated that overexpression of SLC7A11 significantly mitigated joint damage in CIA mice. In vitro experiments demonstrated that overexpression of SLC7A11 inhibited migration, invasion, and Caspase-1 expression levels in TNF-α-induced RA-FLSs. Furthermore, SLC7A11 suppressed inflammation, LDH release, and oxidative stress, while inhibiting pyroptosis. SLC7A11 expression was significantly different in multiple immune cells. The IL-17 pathway was identified as a downstream pathway of SLC7A11, and SLC7A11 inhibited the expression of IL-17 pathway proteins. Additionally, rhIL-17A, an activator of the IL-17 pathway, attenuated the inhibitory effects of SLC7A11 on inflammation, oxidative stress, and pyroptosis.

CONCLUSION

SLC7A11 suppresses pyroptosis to alleviate RA development by inhibiting the IL-17 pathway.

Mechanistic and therapeutic insights into the function of N6-methyladenosine in arthritic diseases

OBJECTIVE

Arthritis is a class of diseases, characterized by joint and surrounding inflammation, accompanied by joint swelling, pain, dysfunction. According to different factors, arthritis can be divided into osteoarthritis, rheumatoid arthritis, ankylosing spondylitis and so on. N6-methyladenosine (m6A) is the most common internal modification of eukaryotic mRNA and is involved in splicing, stabilization, output and degradation of RNA metabolism. This review systematically summarized current insights into the mechanism of m6A in arthritis.

METHODS

The studies related to the involvement of m6A in the pathogenesis of arthritis reported in PubMed, Google scholar, and other open source literatures were investigated to evaluate the important roles of m6A in arhtritis, and the clinical relevances.

RESULTS AND CONCLUSIONS

M6A methylation regulators play the roles of writers, erasers, and readers, are crucial for regulating gene expression, and play important roles in many biological processes such as virus replication and cell differentiation. In addition, more and more studies have shown that m6A is closely related to the development of arthritis. As a new therapeutic target for arthritis, m6A has a wide influence on the pathological mechanism of arthritis. However, further research is needed to determine how m6A affects arthritis pathology and its use in target therapy and diagnosis.

Diagnostic Value of Combined Test of Anti-Cyclic Citrullinated Peptide Antibody, AKA Antibody, Carp Antibody, and Rheumatoid Factor for Rheumatoid Arthritis

OBJECTIVE

To analyze the diagnostic value of a combined test of anti-cyclic citrullinated peptide antibody (CCP), anti-keratin antibody (AKA), anti-carbamylated protein antibody (Carp antibody), and rheumatoid factor (RF) in the early diagnosis of rheumatoid arthritis (RA).

METHODS

Sixty cases of RA admitted to our hospital from 2021 to 2022 (observation group) were selected, along with 50 cases of healthy physical examiners (control group). The results of CCP antibody, AKA antibody, Carp antibody, and rheumatoid factor in both groups were analyzed: the concentration of CCP antibody, AKA antibody, Carp antibody, and rheumatoid factor in each group at different levels; the comparison of various testing methods with the "gold standard" test; and the ROC curve analysis of CCP antibody, AKA antibody, Carp antibody, and rheumatoid factor in each group.

RESULTS

The concentrations of CCP antibody, AKA antibody, Carp antibody, and rheumatoid factor were significantly higher in the observation group than in the control group (p < 0.05). Furthermore, there was a significant increase in the concentrations of CCP antibody, AKA antibody, Carp antibody, and rheumatoid factor from the mild to moderate group (p < 0.05), as well as from the moderate to severe group (p < 0.05). Additionally, when comparing the mild and severe groups, there was a significant elevation in the concentrations of CCP antibody, AKA antibody, Carp antibody (p < 0.05), and rheumatoid factor (p < 0.05).

CONCLUSION

Anti-cyclic citrullinated peptide antibody, AKA antibody, Carp antibody, and rheumatoid factor combined tests have high sensitivity and specificity in the diagnosis of RA.

Rheumatoid arthritis and gliostatin: a two-sample Mendelian randomization analysis and RT-PCR validation

BACKGROUND

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease of unknown etiology. Cuproptosis, a novel form of cell death, is characterized by cytotoxicity originating from copper ions. To date, the relationship between cuproptosis-related gene gliostatin (GLS) and RA.

METHODS

All raw data were retrieved from the Gene Expression Omnibus (GEO) public database. The expression level of genes between RA and healthy samples was evaluated to identify differentially expressed genes. Then, LASSO regression was used to screen disease signature genes, and a nomogram was constructed based on five hub genes to predict disease scores. Validation experiments were performed using quantitative real-time PCR (qRT-PCR) to detect the most significant CRGs. Finally, the causal relationship between GLS and RA was analyzed through Mendelian randomization methodology.

RESULTS

Five differentially expressed CRGs (NLRP3, ATP7A, MTF1, GLS, and DBT) were identified between normal and RA samples, all of which were validated as disease-specific genes through LASSO regression analysis. Meanwhile, the nomogram demonstrated a positive correlation between RA and the expression of GLS. Furthermore, q-PCR revealed that the expression level of GLS was higher in RA patients compared to those in the control group. Taken together, a causal relationship between GLS and RA was corroborated through Mendelian randomization.

CONCLUSION

GLS, a cuproptosis-related gene, is closely associated with RA and plays a significant role in its diagnosis. Key Points • The causal relationship between GLS and RA is proved by Mendelian randomization.

Important Role of Mitochondrial Dysfunction in Immune Triggering and Inflammatory Response in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease, primarily characterized by chronic symmetric synovial inflammation and erosive bone destruction.Mitochondria, the primary site of cellular energy production, play a crucial role in energy metabolism and possess homeostatic regulation capabilities. Mitochondrial function influences the differentiation, activation, and survival of both immune and non-immune cells involved in RA pathogenesis. If the organism experiences hypoxia, genetic predisposition, and oxidative stress, it leads to mitochondrial dysfunction, which further affects immune cell energy metabolism, synovial cell proliferation, apoptosis, and inflammatory signaling, causing the onset and progression of RA; and, mitochondrial regulation is becoming increasingly important in the treatment of RA.In this review, we examine the structure and function of mitochondria, analyze the potential causes of mitochondrial dysfunction in RA, and focus on the mechanisms by which mitochondrial dysfunction triggers chronic inflammation and immune disorders in RA. We also explore the effects of mitochondrial dysfunction on RA immune cells and osteoblasts, emphasizing its key role in the immune response and inflammatory processes in RA. Furthermore, we discuss potential biological processes that regulate mitochondrial homeostasis, which are of great importance for the prevention and treatment of RA.

Building a modular and multi-cellular virtual twin of the synovial joint in Rheumatoid Arthritis

Rheumatoid arthritis is a complex disease marked by joint pain, stiffness, swelling, and chronic synovitis, arising from the dysregulated interaction between synoviocytes and immune cells. Its unclear etiology makes finding a cure challenging. The concept of digital twins, used in engineering, can be applied to healthcare to improve diagnosis and treatment for complex diseases like rheumatoid arthritis. In this work, we pave the path towards a digital twin of the arthritic joint by building a large, modular biochemical reaction map of intra- and intercellular interactions. This network, featuring over 1000 biomolecules, is then converted to one of the largest executable Boolean models for biological systems to date. Validated through existing knowledge and gene expression data, our model is used to explore current treatments and identify new therapeutic targets for rheumatoid arthritis.

Therapeutic potential of antibody-drug conjugates possessing bifunctional anti-inflammatory action in the pathogenies of rheumatoid arthritis

In an age where there is a remarkable upsurge in developing precision medicines, antibody-drug conjugates (ADCs) have emerged as a progressive therapeutic strategy. ADCs typically consist of monoclonal antibodies (mAb) conjugated to the cytotoxic payloads by utilizing a linker, combining the benefits of definitive target specificity of mAbs and potent killing impact of payload to achieve precise and efficient elimination of target cells. In addition to their well-established role in oncology, ADCs are currently demonstrating encouraging potential in addressing the unmet requirements in the treatment of autoimmune conditions such as rheumatoid arthritis (RA). Prevalent long-term autoimmune disease RA costs billions of dollars annually but still, there is a lack of precision-targeted therapeutics with minimal side effects. This review provides an overview of the RA pathogenesis, pre-existing therapies, and their limitations, the introduction of ADCs in RA treatment, the mechanism of ADCs, and a summary of ADCs in preclinical and clinical trials. Based on the literature we also propose a strategy in ADC synthesis, which may increase the efficiency in targeting multifactorial diseases like RA. We propose to utilize DMARDs (Disease-modifying anti-rheumatic drugs), the first-line treatment for RA, as a payload for ADC synthesis. DMARDs are the only class of medication that limits the disease progression, but their efficacy is limited due to off-target toxicities. Hence, utilizing them as payload will help to deliver them directly at the targeted site, reducing their off-target toxicity, which in turn will increase their efficiency in targeting disease. Also, as mAbs are not sufficient to achieve remission, they are given in combinations with DMARDs. Hence, synthesizing ADCs may reduce the multiple and higher dosages given to patients, which in turn may enhance patient compliance.

Transcriptomic integration and ligand-receptor crosstalk reveal the underlying molecular mechanisms between hip cartilage and subchondral bone in osteonecrosis of femoral head

Osteonecrosis of femoral head (ONFH) is characterized not only by ischemic bone tissue necrosis but also by cartilage degeneration, which plays an essential role in the pathogenesis of ONFH. The molecular communication between tissues contributes to disease progression, however the communication between cartilage and subchondral bone in the progression of ONFH remains unclear. In this study, we integrated transcriptomic data from ONFH cartilage and subchondral bone, exploring common differentially expressed genes (DEGs), pathway and function enrichment analyses, the protein-protein interaction (PPI) network, and hub genes to comprehensively study molecular integration. Additionally, we explored the molecular crosstalk between and within cartilage and subchondral bone using ligand-receptor pairs and ONFH cartilage proteomic data. Finally, key genes and ligand-receptor pairs were validated by quantitative real-time PCR (qRT-PCR). There were 27 common DEGs and five hub genes in cartilage and subchondral bone. The defined hub genes included COL1A1, COLIA2, CTSK, SPARC, and MXRA5. Notably, pathways related to ossification, extracellular matrix, and collagen formation were significantly altered in ONFH. Ligand-receptor data combined with DEGs revealed 60 differentially expressed ligands and 51 differentially expressed receptors in cartilage and four ligands and three receptors in subchondral bone. In inter-tissue comparisons, ligands from chondrocytes predominantly paired with receptors on osteoblasts in the subchondral bone, such as FN1, MMP2, and FGF1. Conversely, ligands from osteoblasts and osteocytes in the subchondral bone frequently paired with chondrocyte receptors, including FN1, COL1A1, and SEMA7A. At the protein level, we identified thirteen ligands and one receptor, with COL3A1 being the most highly expressed ligand and CD82 the only differentially expressed receptor in ONFH. This study highlights common molecular mechanisms and ligand-receptor crosstalk between and within cartilage and subchondral bone in ONFH, offering new insights into the disease's pathophysiology and potential molecular targets for therapeutic intervention.

The Role and Research Progress of ACPA in the Diagnosis and Pathological Mechanism of Rheumatoid Arthritis

An autoimmune condition known as rheumatoid arthritis (RA) is characterized by persistent polyarticular inflammation. Within two years of the disease's onset, irreparable bone and joint deterioration can occur as a result of the inflammatory course of the illness, leading to joint deformity and loss of function. In most patients diagnosed with RA, a range of autoantibodies, particularly anti-citrullinated protein antibodies (ACPA), can be detected months to years before the onset of clinically recognizable disease. Additionally, an increasing number of studies suggest that ACPA is involved in the pathogenesis of RA and may play a direct pathogenic role in the disease. This paper focuses on the role of ACPA in the pathomechanism of RA and discusses its unique clinical applications for the early identification and prediction of RA, as well as the influencing factors. Moreover, this article outlines the association of ACPA-positive (ACPA+) RA with other autoimmune diseases.

Inflammatory factor Interleukin-6 and its correlation with rheumatoid arthritis: A meta-analysis

Introduction

at present, there are inconsistent research findings regarding the precise relationship between IL-6 gene polymorphisms (GPMs) and rheumatoid arthritis (RA). This work employed meta-analysis (MA) methodology to systematically evaluate the correlation between IL-6 GPMs and susceptibility to RA.

Material and methods

this study comprehensively searched multiple databases from inception to March 31, 2024. The search utilized keywords including "IL-6," "Interleukin-6," "Cytokines," "Autoimmune diseases," "Arthritis," "rheumatoid arthritis," "Inflammation," "genetic polymorphism," and "genetic variation." Included studies focused on patients diagnosed with rheumatoid arthritis (RA), with healthy individuals or those without RA-related diseases as controls. The study designs encompassed cohort studies and case-control studies. Genetic frequency distributions of IL-6 gene rs1800795 (G-174C), rs1800796 (G-572C), and rs1800797 (G-597A) polymorphic sites were statistically analyzed. Quality of included studies was assessed. The preliminary assessment of literature heterogeneity was conducted. Quantitative assessment of heterogeneity results was performed using the I2 statistic in RevMan5.3. Publication bias (PB) assessment was conducted.

Result

the study included a total of 21 articles, comprising 9772 participants, with 4679 cases diagnosed with RA and 5093 individuals in the control (CT) group. The IL-6 gene allelic model (G vs C) exhibited a notable association with RA [OR = 0.66, 95%CI: 0.51-0.87, Z = 3.02, P = 0.003]. In Southeast Asian populations, IL-6 gene rs1800795 (G-174C) genotype (CC) demonstrated a considerable correlation with RA [OR = 15.23, 95%CI: 3.53-65.67, P = 0.00003]. IL-6 gene rs1800795 (G-174C) genotype (CG) was associated with RA [OR = 1.54, 95%CI: 1.10-2.17, Z = 2.48, P = 0.01], with only the Asian population showing an observable correlation [OR = 6.55, 95%CI: 1.28-33.45, P = 0.02]. Additionally, IL-6 rs1800795 (G-174C) genotype (GG) was associated with RA [OR = 0.66, 95%CI: 0.49-0.91, Z = 2.55, P = 0.01], with notable associations observed in the Asian [OR = 0.17, 95%CI: 0.03-0.83, P = 0.03] and mixed populations [OR = 1.29, 95%CI: 1.011.65, P = 0.04]. No correlation was found between rs1800796 (G-572C) and rs1800797 (G-597A) GPMs and RA (P > 0.05).

Conclusion

IL-6 gene rs1800795 (G-174C) allelic model and genotypes (CC, CG, GG) were all associated with susceptibility to RA, with the G allele model being susceptible in Southeast Asian populations, and genotypes (CG and GG) being susceptible in Asian populations. However, there was neglectable correlation between rs1800796 (G-572C) and rs1800797 (G-597A) GPMs and susceptibility to RA.

Association between plasma trans fatty acid levels and rheumatoid arthritis: a cross-sectional study using NHANES 1999-2000 and 2009-2010 data in US adults

Objective

While earlier research has indicated that trans fatty acids (TFAs) are detrimental to cardiovascular health as well as other conditions, the purpose of this study is to look into any possible connections between trans fatty acids and rheumatoid arthritis (RA).

Methods

The NHANES database provided the data for this study, covering two periods: 1999-2000 and 2009-2010. The correlation between plasma TFAs (linolelaidic acid, vaccenic acid, palmitelaidic acid, and elaidic acid) and RA was examined using weighted univariate and multivariate regression analyses as well as analysis of subgroups. Additionally, this study used restricted cubic spline curves to investigate the non-linear relationship between them.

Results

This study included 2,938 patients, of whom 222 (7.56%) had RA. Multivariate logistic regression analysis showed that levels of linolelaidic acid were linked to a higher risk of RA (odds ratio = 1.39, 95% confidence interval = 1.05-1.85, p = 0.025) after accounting for all other variables. No significant effect on this association was found in interaction tests. A linear association between linolelaidic acid and RA was demonstrated in the limited cubic spline regression model. For RA, linolelaidic acid exhibited a critical value of 0.98.

Conclusion

Findings suggesting a possible link between elevated plasma TFA levels and an increased risk of RA offer fresh perspectives on RA prevention through dietary interventions.

Emerging influence of RNA post-transcriptional modifications in the synovial homeostasis of rheumatoid arthritis

Rheumatoid arthritis (RA) is an important autoimmune disease that affects synovial tissues, accompanied by redness, pain, and swelling as main symptoms, which will limit the quality of daily life and even cause disability. Multiple coupling effects among the various cells in the synovial micro-environment modulate the poor progression and development of diseases. Respectively, synovium is the primary target tissue of inflammatory articular pathologies; synovial hyperplasia, and excessive accumulation of immune cells lead to joint remodelling and destroyed function. In general, epigenetic modification is an effective strategy to regulate dynamic balance of synovial homeostasis. Several typical post-transcriptional changes in cellular RNA can control the post-transcriptional modification of RNA structure. It can inhibit important processes, including degradation of RNA and nuclear translocation. Recent studies have found that RNA modification regulates the homeostasis of the synovial micro-environment and forms an intricate network in the "bone-cartilage-synovium" feedback loop. Aberrant regulation of RNA methylation triggers the pathological development of RA. Collectively, this review summarises recent advanced research about RNA modification in modulating synovial homeostasis by making close interaction among resident synovial macrophages, fibroblasts, T cells, and B cells, which could display the dramatic role of RNA modifications in RA pathophysiological process and perform the promising therapeutic target for treating RA.

VE-cadherin may suppress inflammation depending on the phase of inflammation of rheumatoid arthritis

Objectives A disintegrin and metalloproteinase (ADAM)-15 and vascular endothelial (VE)-cadherin are involved in angiogenesis. We investigated the relationship between ADAM-15 and VE-cadherin expressions in rheumatoid arthritis (RA). Methods VE-cadherin concentrations in the serum of patients with RA were measured using the enzyme linked immunosorbent assay (ELISA). We stimulated fibroblast-like synoviocytes (RA-FLS) with VE-cadherin and measured the vascular endothelial growth factor (VEGF) and inflammatory cytokine levels using ELISA. We also examined the correlation between serum VE-cadherin levels and DAS-28ESR and used the Matrigel assay to examine VE-cadherin involvement in angiogenesis. Results Serum VE-cadherin levels were significantly higher in patients with RA than in healthy controls. A negative correlation was observed between VE-cadherin and DAS-28ESR. VEGF, chemokine ligand 16, intercellular adhesion molecule-1, and interleukin-8 levels in the supernatant of RA-FLS or human umbilical vein endothelial cells stimulated with VE-cadherin were significantly lower than those in the controls. The number of intercellular bridges formed by endothelial cells using Matrigel significantly decreased in RA synovial fluids from which VE-cadherin had been removed compared to synovial fluids treated with control immunoglobulin G. Conclusion VE-cadherin may have an inhibitory effect on inflammation depending on the phase of RA inflammation.

Piperine and piperine-loaded albumin nanoparticles ameliorate adjuvant-induced arthritis and reduce IL-17 in rats

AIM

Rheumatoid arthritis (RA) is one of the most common chronic, inflammatory, autoimmune diseases affecting mainly the joints. Piperine (PIP), an alkaloid found in black pepper, has anti-inflammatory properties and its use in drug delivery systems such as nanoparticles might be a treatment for RA. This study aims to evaluate the possible anti-inflammatory and anti-arthritic effects of PIP and its use in albumin nanoparticles as a possible approach for the treatment of Adjuvant-induced arthritis (AIA) rats.

METHODS

PIP-loaded Bovine Serum Albumin nanoparticles (PIP-BSA NPs) were prepared using a desolvation method. AIA rats were given intraperitoneal injections of either 40 mg PIP or 131 mg PIP-BSA NPs every two days until day 28 when animals were sacrificed. Clinical score, histopathology, X-ray radiography, and serum levels of pro-inflammatory cytokines such as IL-1β, IL-17, and TNF-α were evaluated.

RESULTS

PIP and PIP-BSA NPs significantly reduced clinical scores, and alleviated inflammation within the joints. PIP was superior to PIP-BSA NPs for the alleviation of fibrin deposition and periosteal reactions while bone inflammation and erosion were less severe in the case of PIP-BSA NPs. Besides, both of the treatments suppressed serum levels of IL-17 in AIA rats (p = 0.003 and p = 0.02; respectively).

CONCLUSIONS

PIP and PIP-BSA NPs effectively alleviate the severity of AIA and suppress inflammation. Due to the superiority of PIP in improving fibrin deposition and periosteal reactions and the efficacy of PIP-BSA NPs in suppressing bone inflammation and erosion, their simultaneous use might be investigated.

Identification of Hub Genes and Prediction of Targeted Drugs for Rheumatoid Arthritis and Idiopathic Pulmonary Fibrosis

There is a potential link between rheumatoid arthritis (RA) and idiopathic pulmonary fibrosis (IPF). The aim of this study is to investigate the molecular processes that underlie the development of these two conditions by bioinformatics methods. The gene expression samples for RA (GSE77298) and IPF (GSE24206) were retrieved from the Gene Expression Omnibus (GEO) database. After identifying the overlapping differentially expressed genes (DEGs) for RA and IPF, we conducted functional annotation, protein-protein interaction (PPI) network analysis, and hub gene identification. Finally, we used the hub genes to predict potential medications for the treatment of both disorders. We identified 74 common DEGs for further analysis. Functional analysis demonstrated that cellular components, biological processes, and molecular functions all played a role in the emergence and progression of RA and IPF. Using the cytoHubba plugin, we identified 7 important hub genes, namely COL3A1, SDC1, CCL5, CXCL13, MMP1, THY1, and BDNF. As diagnostic indicators for RA, SDC1, CCL5, CXCL13, MMP1, and THY1 showed favorable values. For IPF, COL3A1, SDC1, CCL5, CXCL13, THY1, and BDNF were favorable diagnostic markers. Furthermore, we predicted 61 Chinese and 69 Western medications using the hub genes. Our research findings demonstrate a shared pathophysiology between RA and IPF, which may provide new insights for more mechanistic research and more effective treatments. These common pathways and hub genes identified in our study offer potential opportunities for developing more targeted therapies that can address both disorders.

The Causal Relationship Between Genetically Determined Plasma Metabolites and Rheumatoid Arthritis

BACKGROUND

Presently, research examining the impact of plasma metabolites on rheumatoid arthritis (RA) is scarce. We utilized a bidirectional two-sample Mendelian randomization (MR) analysis to explore the potential causal link between 1400 plasma metabolites and RA.

METHODS

We performed a two-sample MR analysis to assess the causal association between 1400 plasma metabolites and RA. The primary method of two-sample MR Analysis was the Inverse Variance Weighted (IVW) model, and the secondary methods were the Weighted Median (WM) and MR Egger methods. We conducted sensitivity analyses using Cochran's Q test, MR-Egger intercept test, MR-PRESSO, and Leave-One-Out analyses. Steiger test was used for validation of the metabolites. The main results were validated in the UK Biobank.

RESULTS

In the discovery dataset, 60 metabolites were identified as significantly associated with the onset of RA. A notable finding was the strong correlation between Valve levels and RA risk, showing the highest positive correlation (OR [95% CI]: 1.361 (1.112, 1.667), p = 0.0028). Subsequent analysis of the validation dataset revealed 46 metabolites linked to RA, with X-22771 levels displaying the strongest positive association (OR [95% CI]: 1.002 (1.00, 1.004), p = 0.037). Notably, Glycohydrocolate levels exhibited a protective effect on RA in both datasets. Specifically, the effect size in the initial dataset was (OR [95% CI]:0.867 (0.753, 1.000), p = 0.050), whereas in the validation dataset, the effect was weaker (OR [95% CI]: 0.999 (0.997, 1.000), p = 0.048). These findings were further validated through a series of sensitivity analyses, affirming their robustness and reliability.

CONCLUSIONS

This study highlights a strong correlation between elevated Valine levels and an increased risk of RA, as well as potential protective effects of Glycohydrohorate in independent datasets.

microRNAs: critical targets for treating rheumatoid arthritis angiogenesis

Vascular neogenesis, an early event in the development of rheumatoid arthritis (RA) inflammation, is critical for the formation of synovial vascular networks and plays a key role in the progression and persistence of chronic RA inflammation. microRNAs (miRNAs), a class of single-stranded, non-coding RNAs with approximately 21-23 nucleotides in length, regulate gene expression by binding to the 3' untranslated region (3'-UTR) of specific mRNAs. Increasing evidence suggests that miRNAs are differently expressed in diseases associated with vascular neogenesis and play a crucial role in disease-related vascular neogenesis. However, current studies are not sufficient and further experimental studies are needed to validate and establish the relationship between miRNAs and diseases associated with vascular neogenesis, and to determine the specific role of miRNAs in vascular development pathways. To better treat vascular neogenesis in diseases such as RA, we need additional studies on the role of miRNAs and their target genes in vascular development, and to provide more strategic references. In addition, future studies can use modern biotechnological methods such as proteomics and transcriptomics to investigate the expression and regulatory mechanisms of miRNAs, providing a more comprehensive and in-depth research basis for the treatment of related diseases such as RA.

Analysis and identification of ferroptosis-related diagnostic markers in rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is an autoimmune, inflammatory joint disease. There is growing evidence that ferroptosis is involved in the pathogenesis of RA. This study aimed to search for diagnostic markers of ferroptosis in RA and to analyse the potential mechanisms and clinical value.

MATERIALS AND METHODS

RA-associated datasets were used from the publicly available GEO database. Three methods of machine learning were applied to screen biomarkers. The diagnostic efficacy of the results was also verified by receiver operating characteristic (ROC) curve, external dataset, qRT-PCR and Western blot. Enrichment analysis was performed in this process, while protein-protein interaction (PPI) analysis and immune infiltration correlation analysis were performed using biomarkers, and competing endogenous RNA (ceRNA) networks were constructed to search for prospective therapeutic targets.

RESULTS

MMP13 and GABARAPL1 can be used as ferroptosis diagnostic genes in RA. The ROC curve and PPI result demonstrated that MMP13 and GABARAPL1 had an excellent diagnostic value. The results of signature genes in the external dataset, qRT-PCR and Western blot further confirm our findings. The enrichment analysis showed that p53, MAPK and NOD-like receptor signalling pathways may be involved in the process of ferroptosis in RA. In addition, two ferroptosis diagnostic genes in RA participate in the occurrence of ferroptosis in RA via oxidative stress, metabolism and immune response. Immune infiltration analysis showed that RA extensively infiltrated B cells, T cells, macrophages and other immune cells. Persistent immune activation may be an essential reason for the progression of ferroptosis in RA. We also obtained five potential therapeutic agents for RA and some long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) regulating ferroptosis diagnostic genes.

CONCLUSIONS

Our study suggests that MMP13 and GABARAPL1, which are closely linked with oxidative stress and immunological modulation, can be used as ferroptosis-related potential diagnostic markers in RA and provide new clues regarding the diagnostic and therapeutic targets of ferroptosis in RA.

Altered serum metabolome is associated with disease activity and immune responses in rheumatoid arthritis

Rheumatoid arthritis (RA) is widespread globally, with the emergence of metabolites derived from both the host and microbes playing a pivotal role in its pathogenesis. This study aims to elucidate the relationships between serum metabolites and the immunological and clinical features of RA. Serum samples were collected from 35 RA patients and 37 healthy controls (HC). Metabolite profiling was performed using gas chromatography-mass spectrometry (GC/MS). Principal component analysis revealed a significant distinction between the RA and HC cohorts. Employing univariate statistical analysis, we identified 36 differential metabolites. Among these, 9 metabolites, including galactose and glucose, were found to be enriched, while the remaining metabolites, such as citric acid, fumaric acid, and inosine, were depleted in RA. These diverse metabolites encompassed various metabolic processes, including the biosynthesis of fatty acids, amino acids, and glucose. The enrichment of glucose and galactose in RA exhibited a substantial correlation with elevated IgG levels, as determined through correlation analysis. Conversely, the depletion of citric acid was correlated with elevated levels of C3 and CRP. Methionine, which also declined in RA patients, displayed a negative correlation with ESR. Furthermore, galactose and glucose exhibited significant positive correlations with naïve B cells, while the decreased eicosanoic acid level in RA was significantly associated with an increase in natural killer cells. Our findings suggest that the altered serum metabolite profile in RA is closely linked to disease severity and the dysregulated immune responses observed in RA patients. Key Points • Identified nine metabolites with upregulated expression and twenty-seven metabolites with downregulated expression. • Established a correlation between alterations in serum metabolite levels and inflammatory markers in RA patients. • Discovered a significant association between changes in serum metabolites and immune cell profiles in RA patients.

Prevention of rheumatoid arthritis using a familial predictive medicine approach

Most of the chronic-degenerative diseases deserve a very early recognition of symptoms and signs for the earliest secondary prevention, which could be also very useful in many cases for the most precocious clinical approach. The periodic monitoring of a subject at risk of a specific disease, because of genomic predisposition by predictive medicine approach, may help to earlier detection of onset and/or the progression of the pathology itself, through intra-individual monitoring. This is particularly the case of rheumatoid arthritis (RA) for which an early diagnosis is undoubtedly the first step to ensure the most proper therapy for the patient. Thus, the earlier identification of individuals at high risk of RA could lead to ultra-preventive strategies to start for the best lifestyle performances and/or for any other effective therapeutic interventions to contrast the onset, and/or the evolution of the putative RA. This will also optimize both costs and medical resources, according to the health care policies of many countries.

Genetic variants in the TNF pathway impact TNFi response in a mixed population with rheumatoid arthritis

Rheumatoid arthritis (RA) is a multifactorial autoimmune inflammatory disease that mainly affects the joints, on reducing functional capacity and impacting quality of life. Cytokines such as tumor necrosis factor (TNF) and interleukin 6 (IL-6) are crucial in the pathogenesis and treatment of this disease. Some patients using TNF inhibitors (TNFi) do not respond or lose their response to these medications. Clinical, sociodemographic, and genetic data were used to evaluate the associations of single nucleotide polymorphisms (SNP) in TNF, TNFRSF1A, and TNFRSF1B genes with the diagnosis of RA, standardized score results, laboratory tests, and response to TNFi. In one subsample, TNF and IL-6 serum levels cytokines were performed. A total of 654 subjects (360 healthy controls and 294 diagnosed with RA) were included in the analysis. Higher levels of TNF have been found in individuals diagnosed with RA. IL-6 levels were higher in individuals who did not respond to TNFi treatment, while responders had levels comparable to those without the disease. No associations were found between the SNPs studied and the diagnosis of RA; however, rs767455-C seems to play a role in the response to golimumab treatment, being related to better therapeutic response and lower mean serum leukocyte levels. In addition, rs1061622-G was associated with poorer functional capacity and rs1800629-A was associated with higher leukocyte values and serum transaminase levels. The rs1061622-G and rs767455-C may play a role in the response to TNFi treatment, especially for patients using golimumab, although they do not seem to be associated with the diagnosis of RA. Polymosphisms in the TNF pathway may impact baseline levels of immune cells and markers of renal and hepatic function in RA patients. Our results highlight the importance of evaluating the impact of these polymorphisms on TNFi response and safety, particularly in larger-scale studies.

Brain-immune interactions: implication for cognitive impairments in Alzheimer's disease and autoimmune disorders

Progressive memory loss and cognitive dysfunction, encompassing deficits in learning, memory, problem solving, spatial reasoning, and verbal expression, are characteristics of Alzheimer's disease and related dementia. A wealth of studies has described multiple roles of the immune system in the development or exacerbation of dementia. Individuals with autoimmune disorders can also develop cognitive dysfunction, a phenomenon termed "autoimmune dementia." Together, these findings underscore the pivotal role of the neuroimmune axis in both Alzheimer's disease and related dementia and autoimmune dementia. The dynamic interplay between adaptive and innate immunity, both in and outside the brain, significantly affects the etiology and progression of these conditions. Multidisciplinary research shows that cognitive dysfunction arises from a bidirectional relationship between the nervous and immune systems, though the specific mechanisms that drive cognitive impairments are not fully understood. Intriguingly, this reciprocal regulation occurs at multiple levels, where neuronal signals can modulate immune responses, and immune system-related processes can influence neuronal viability and function. In this review, we consider the implications of autoimmune responses in various autoimmune disorders and Alzheimer's disease and explore their effects on brain function. We also discuss the diverse cellular and molecular crosstalk between the brain and the immune system, as they may shed light on potential triggers of peripheral inflammation, their effect on the integrity of the blood-brain barrier, and brain function. Additionally, we assess challenges and possibilities associated with developing immune-based therapies for the treatment of cognitive decline.

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.

Advances of the multifaceted functions of PSTPIP2 in inflammatory diseases

The complex interaction between the immune system and autoinflammatory disorders highlights the centrality of autoimmune mechanisms in the pathogenesis of autoinflammatory diseases. With the exploration of PSTPIP2, it has been discovered to play an inhibitory role in immune diseases, suggesting its potential utility in the research and treatment of rheumatic diseases. This review outlines the mechanisms of PSTPIP2 in chronic multifocal osteomyelitis (CMO), rheumatoid arthritis (RA), synovitis-acne-pustulosis-hyperostosis-osteitis (SAPHO) syndrome, liver diseases, renal diseases, pressure ulcer sepsis and diabetic obesity. The mechanisms include inhibiting the IL-1β inflammatory responses, NF-κB, ERK phosphorylation etc., promoting Erβ, and modulating the polarization of macrophage to prevent the inflammatory diseases. This review summarized current findings and offered perspectives on future research directions, laying a foundation for applying of PSTPIP2 in inflammatory diseases.

Synovial Fluid Immune Cell Composition Following Intraarticular Fracture May Contribute to Posttraumatic Osteoarthritis

Intra-articular ankle fracture (IAF) often leads to post-traumatic osteoarthritis (PTOA), resulting in significant long-term morbidity. While previous research has focused on the inflammatory cytokines and matrix metalloproteinases within the synovial fluid fracture hematoma (SFFH), the immune cell populations within SFFH that contribute to PTOA development remain underexplored. This study aimed to characterize the immune cell populations in SFFH to better understand their role in the inflammatory response and potential for inducing lasting cartilage damage. Twenty-four patients with IAF underwent surgical ankle aspiration to collect SFFH, which was analyzed using polychromatic flow cytometry. The analysis revealed that 72.8% of the CD45+ cells were lymphocytes, predominantly CD3+ T cells (76.5%), with 42.1% being CD4+ and 39.2% CD8+ T cells. Additionally, monocytes accounted for 21.2% of CD45+ cells, with small populations of natural killer cells and myeloid-derived suppressor cells also present. These findings emphasize the predominance of T cells, particularly CD4+ subsets, in the immune response following IAF. Understanding these dynamics is essential for developing targeted interventions to prevent PTOA. Future research should focus on elucidating the specific roles of these immune cell populations in PTOA progression and exploring potential therapeutic strategies.

Nonlinear association between platelet to albumin ratio and disease activity in patients with early rheumatoid arthritis

The relationship between the platelet to albumin ratio (PAR) and the disease activity of early rheumatoid arthritis (ERA) remains to be elucidated. This cross-sectional study included 372 patients with ERA who were hospitalized at Xingtai People's Hospital between January 2022 and January 2024. Multiple linear regression analysis was employed to assess the correlation of PAR with Disease Activity Score 28 (DAS28) using erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), and then generalized additive models were used to explore their relationship. After accounting for confounding variables, a positive correlation was observed between the PAR and DAS28-ESR and DAS28-CRP in ERA patients (β (95% CI): 0.20 (0.08, 0.32) and 0.20 (0.08, 0.33), respectively), and the general trends were consistent from the lowest tertile group (T1) to the highest tertile group (T3). Furthermore, a nonlinear relationship was identified between PAR and both DAS28-ESR and DAS28-CRP. Threshold effect analysis indicated that a value of 13.73 was a significant inflection point. In brief, PAR has a threshold effect on the disease activity of ERA. Increased PAR levels were independently positive associated with DAS28-ESR and DAS28-CRP among ERA patients with PAR < 13.73.

Sinulariolide Suppresses Inflammation of Fibroblast-Like Synoviocytes in Rheumatoid Arthritis and Mitigates Collagen-Induced Arthritis Symptoms in Mice

Background

Rheumatoid arthritis (RA) is a systemic inflammatory disease characterized by active polyarthritis, which leads to functional loss and joint deformities. Natural compounds derived from marine organisms are considered valuable immune-modulating agents. This study aimed to assess the anti-inflammatory effect of sinulariolide, a soft coral-derived compound, on RA fibroblast-like synoviocytes and its therapeutic efficacy against collagen-induced arthritis (CIA).

Methods

To determine the effects of sinulariolide on tumor necrosis factor-alpha (TNF-α)-induced inflammation, MH7A cells pre-treated with 10 ng/mL TNF-α for 24 h were treated with sinulariolide. The effect of sinulariolide on proinflammatory cytokine expressions at both the mRNA and protein levels in the MH7A cells was assessed using real-time-polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA). Further, we analyzed the effect of sinulariolide on the activation of mitogen-activated protein kinase (MAPK) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathways using Western blotting and the TransAM NF-κB p65 kit. To comprehensively evaluate the potential application of sinulariolide in the treatment of inflammatory diseases, we used a well-established collagen-induced arthritis (CIA) mouse model. We examined the tissue sections of the ankle joints of the mice, assessed synovial hyperplasia, inflammatory cell infiltration, and cartilage damage, and used ELISA to analyze changes in cytokine expression in the hind paw tissues.

Results

MH7A cells treated with sinulariolide showed a notable reduction in the expression of proinflammatory cytokines, which could be due to decreased activation of the MAPK and NF-kB pathways. Additionally, sinulariolide-treated mice showed significantly reduced joint swelling and lower clinical arthritis scores than those in the normal and control groups. Significant reductions in synovial hyperplasia, inflammatory cell infiltration, and cartilage damage were observed in the tissue sections of the ankle joints of the mice treated with sinulariolide. Furthermore, the expression of inflammatory cytokines in the hind paw tissue of the mice treated with sinulariolide was significantly decreased.

Conclusion

Sinulariolide inhibited the progression of inflammation in MH7A cells. Sinulariolide treatment significantly reduced clinical arthritis symptoms and histological inflammatory responses in mice with CIA. Sinulariolide may serve as a potential therapeutic agent for RA.

Application of superb microvascular imaging technology in clinical disease activity of rheumatoid arthritis

OBJECTIVES

Detection of synovitis is essential for assessing the activity and predicting the prognosis of rheumatoid arthritis (RA). The aim of this study was to investigate the diagnostic performance of superb microvascular imaging (SMI) in RA patients with high, moderate, and low activity.

METHODS

One hundred four patients with active RA were selected from the hospital between May 2022 and August 2023. The study observed the correlation between bone erosion of the carpal joint, joint cavity effusion, thickness of synovial hyperplasia of the carpal joint, positivity rate of synovial blood vessels, and their semiquantitative scores with the clinical disease activity of RA using SMI examination.

RESULTS

The detection of synovial hyperplasia thickness and joint effusion in the high-activity group was higher than that in the low-activity group, and the difference was statistically significant (P < 0.05). The quantitative SMI test demonstrated that the synovial blood flow grading and semiquantitative grade increased gradually with activity level (P<0.05). During the high, moderate, and low-activity groups, the vascular index (VI) value of the hyperplastic synovial membrane decreased gradually, showing statistical significance both between and within the groups (P<0.05).

CONCLUSION

SMI technology exhibited high sensitivity and accuracy in assessing disease activity in RA. It holds significant clinical application value as a reliable auxiliary tool for assessing disease activity in RA and treatment. Key Points • Super micro-vascular imaging (SMI) demonstrated higher detection rates of microvessels in RA patients with high disease activity compared to those with low activity, showing statistical significance. • The quantitative SMI test revealed a clear correlation between synovial blood flow grading and disease activity levels in RA patients, highlighting the potential of SMI as a valuable tool for disease activity and treatment of rheumatoid arthritis.

CCR5 mediates rheumatoid arthritis progression by promoting the activation and proliferation of non-classical Th1 cells

AIM

Rheumatoid arthritis (RA) is a prevalent autoimmune disease characterized by immune dysegulation, including an immune imbalance due to abnormal activation of non-classical Th1 cells (CD161+ Th1). This study investigated the effects of CCR5 on the activation and proliferation of CD161+ Th1 and their pathogenicity in patients with RA.

METHODS

The study was conducted on 53 patients with RA and 32 age- and sex-matched healthy controls (HC). The cell phenotype was assessed by flow cytometry and the cytokine levels in the supernatant were detected by ELISA.

RESULTS

We demonstrate a marked increase in CD161+ Th1 cells in the synovial fluid of RA patients. These cells exhibit a hyperactivated and hyperproliferative state alongside elevated CCR5 expression. Furthermore, the levels of CD161+ Th1 cells, CD25, and CCR5 in RA synovial fluid show a positive correlation with the disease activity. Additionally, our study reveals that CCR5 facilitates the activation, proliferation, and cytokine production of CD161+ Th1 cells through the pZAP70/NFAT signaling pathway.

CONCLUSION

These findings contribute to a deeper understanding of RA pathogenesis and uncover a novel mechanism that regulates non-classical CD161+ Th1 responses in RA, which may provide a potential therapeutic target.

Schistosoma antigens: A future clinical magic bullet for autoimmune diseases?

Autoimmune diseases are characterized by dysregulated immunity against self-antigens. Current treatment of autoimmune diseases largely relies on suppressing host immunity to prevent excessive inflammation. Other immunotherapy options, such as cytokine or cell-targeted therapies, have also been used. However, most patients do not benefit from these therapies as recurrence of the disease usually occurs. Therefore, more effort is needed to find alternative immune therapeutics. Schistosoma infection has been a significant public health problem in most developing countries. Schistosoma parasites produce eggs that continuously secrete soluble egg antigen (SEA), which is a known modulator of host immune responses by enhancing Th2 immunity and alleviating outcomes of Th1 and Th17 responses. Recently, SEA has shown promise in treating autoimmune disorders due to their substantial immune-regulatory effects. Despite this interest, how these antigens modulate human immunity demonstrates only limited pieces of evidence, and whether there is potential for Schistosoma antigens in other diseases in the future remains an unsolved question. This review discusses how SEA modulates human immune responses and its potential for development as a novel immunotherapeutic for autoimmune diseases. We also discuss the immune modulatory effects of other non-SEA schistosome antigens at different stages of the parasite's life cycle.

Immunoregulation and male reproductive function: Impacts and mechanistic insights into inflammation

This paper investigates the complex relationship between the immune system and male reproductive processes, emphasizing how chronic inflammation can adversely affect male reproductive health. The immune system plays a dual role; it protects and regulates reproductive organs and spermatogenesis while maintaining reproductive health through immune privilege in the testes and the activities of various immune cells and cytokines. However, when chronic inflammation persists or intensifies, it can disrupt this balance, leading to immune attacks on reproductive tissues and resulting in infertility.This study provides a detailed analysis of how chronic inflammation can impair sperm production, sperm quality, and the secretion of gonadal hormones both directly and indirectly. It also delves into the critical roles of testicular immune privilege, various immune cells, and cytokines in sustaining reproductive health and examines the impacts of infections, autoimmune diseases, and environmental factors on male fertility.

The application prospects of sacha inchi (Plukenetia volubilis linneo) in rheumatoid arthritis

Sacha Inchi (Plukenetia volubilis L) (SI) is a traditional natural medicine from tropical rainforests of Amazon region in South America. As a raw material for edible oil, it has various pharmacological effects such as antioxidant, anti-inflammatory, hypolipidemia, and blood pressure lowering, which have attracted increasing attentions of pharmacists. This has prompted researchers to explore its pharmacological effects for potential applications in certain diseases. Among these, the study of its anti-inflammatory effects has become a particularly interesting topic, especially in rheumatoid arthritis (RA). RA is a systemic autoimmune disease, and often accompanied by chronic inflammatory reactions. Despite significant progress in its treatment, there is still an urgent need to find effective anti-RA drugs in regard to safety. This review summarizes the potential therapeutic effects of SI on RA by modulating gut microbiota, targeting inflammatory cells and pathways, and mimicking biologic antibody drugs, predicting the application prospects of SI in RA, and providing references for research aimed at using SI to treat RA.

Evaluation of the Anti-Inflammatory/Immunomodulatory Effect of Teucrium montanum L. Extract in Collagen-Induced Arthritis in Rats

The anti-inflammatory/immunomodulatory effects of Teucrium montanum L. (TM), a plant distributed in the Mediterranean region, have been insufficiently examined. The effects of the TM ethanol extract were tested in a rat collagen-induced arthritis (CIA) model of rheumatoid arthritis. LC-MS was used for the phytochemical analysis of the TM extract. Dark Agouti rats were immunized with bovine type II collagen (CII) in incomplete Freund's adjuvant for CIA, and treated with 100 or 200 mg/kg of TM extract daily via oral administration. Clinical and histopathological evaluations and a flow cytometric analysis of the phenotypic and functional characteristics of splenocytes and draining lymph node cells were performed. The cytokines in the paw tissue culture supernatants and anti-CII antibodies in serum were determined by ELISA. The TM extract, with the dominant components verbascoside and luteolin 7-O-rutinoside, reduced the arthritic score and ankle joint inflammation in CIA rats, promoted the antioxidant profile in serum, and lowered pro-inflammatory TNF-α, IL-6 and IL-1β production. It suppressed the activation status of CD11b+ cells by lowering CD86, MHCII and TLR-4 expression, and promoted the Th17/T regulatory cell (Tregs) balance towards Tregs. A lower frequency of B cells was accompanied by a lower level of anti-CII antibodies in treated rats. These findings imply the favorable effect of TM extract on the clinical presentation of CIA, suggesting its anti-inflammatory/immunomodulatory action and potential therapeutic effect.

Association between vitamin B6 levels and rheumatoid arthritis: a two-sample Mendelian randomization study

Background

Micronutrients play a crucial role in rheumatoid arthritis (RA). Changes in micronutrient levels in RA patients can lead to the worsening of their condition. Though significant correlations between RA and micronutrients have been found in earlier observational studies, their underlying causal relationship is still unknown. This study aimed to elucidate the causal genetic relationships between 15 micronutrients (copper, zinc, magnesium, vitamins A, C, E, D, B6, B12, folate, carotene, iron, selenium, calcium, potassium) and RA.

Method

The exposure factors and outcome data used in the two-sample Mendelian randomization (MR) were derived from publicly available summary statistics data of European populations. The GWAS data for exposure factors were obtained from the OpenGWAS database. For the outcome data of RA, we utilized data from the FinnGen database. We used the MR principle to remove confounding factors and conducted MR analyses using five methods: inverse variance weighted (IVW), MR Egger, weighted median, simple mode, and weighted mode, with IVW as the primary method. Then, we identified micronutrients related to RA and performed MR analyses on these elements, including heterogeneity analysis and pleiotropy analysis such as MR-Egger intercept, MR-PRESSO method, and "leave-one-out" analysis. Finally, we conducted multivariable MR analyses and performed sensitivity analyses again.

Results

The IVW analysis revealed a relationship between vitamin B6 and RA (p: 0.029, OR: 1.766, and 95% CI: 1.062-2.938). Sensitivity analysis confirmed the validity and reliability of this result.

Conclusion

This study revealed a causal relationship between vitamin B6 and RA, with vitamin B6 being identified as a risk factor for RA. This finding could contribute to the diagnosis and supplementary treatment of RA patients, providing a reference for subsequent basic research and developing new drugs.

Visnagin alleviates rheumatoid arthritis via its potential inhibitory impact on malate dehydrogenase enzyme: in silico, in vitro, and in vivo studies

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disorder. The present study aimed to evaluate the in silico, in vitro, and in vivo inhibitory effect of visnagin on malate dehydrogenase activity and elucidate its inflammatory efficacy when combined with methotrexate in the RA rat model. The molecular docking, ADMET simulations, MDH activity, expression, and X-ray imaging were detected. Moreover, CRP, RF, (anti-CCP) antibody, (TNF-α), (IL-6), (IL-17), and (IL-10) were evaluated. The expression levels of MMP3 and FOXP3 genes and CD4, CD25, and CD127 protein levels were assessed. Histological assessment of ankle joints was evaluated. The results revealed that visnagin showed reversible competitive inhibition on MDH with inhibitory constant (Ki) equal to 141 mM with theoretical IC50 equal to 1202.7 mM, LD50 equal to 155.39 mg/kg, and LD25 equal to 77.69 mg/kg. In vivo studies indicated that visnagin exhibited anti-inflammatory effects through decreasing MDH1 activity and expression and induced proliferation of anti-inflammatory CD4+CD25+FOXP3 regulatory T cells with increasing the anti-inflammatory cytokine IL-10 levels. Moreover, visnagin reduced the levels of inflammatory cytokines and the immuno-markers. Our findings elucidate that visnagin exhibits an anti-inflammatory impact against RA through its ability to inhibit the MDH1 enzyme, improve methotrexate efficacy, and reduce oxidative stress.

Ganlu formula ethyl acetate extract (GLEE) blocked the development of experimental arthritis by inhibiting NLRP3 activation and reducing M1 type macrophage polarization

ETHNOPHARMACOLOGICAL RELEVANCE

The Tibetan medicine Ganlu Formula, as a classic prescription, is widely used across the Qinghai-Tibet Plateau area of China, which has a significant effect on relieving the course of rheumatoid arthritis (RA). However, the active compounds and underlying mechanisms of Ganlu Formula in RA treatment remain largely unexplored.

AIM OF THE STUDY

This study aimed to elucidate the active substances and potential mechanisms of the ethyl acetate extract of Ganlu Formula ethyl acetate extract (GLEE) in the treatment of RA.

MATERIALS AND METHODS

Ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was utilized to analyze and identify the chemical constituents within GLEE. Discovery Studio molecular virtual docking technology was utilized to dock the interaction of GLEE with inflammation-related pathway proteins. The GLEE gene library was obtained by transcriptome sequencing. Collagen-induced arthritic（CIA) rats were utilized to assess the antiarthritic efficacy of GLEE. Micro-CT imaging was employed to visualize the rat paw, and ultrasound imaging revealed knee joint effusion. Evaluation of synovial tissue pathological changes was conducted through hematoxylin-eosin staining and saffranine solid green staining, while immunohistochemical staining was employed to assess NLRP3 expression along with inflammatory markers. Immunofluorescence staining was utilized to identify M1 macrophages.

RESULTS

Metabolomic analysis via UPLC-Q-TOF-MS identified 28 potentially bioactive compounds in GLEE, which interacted with the active sites of key proteins such as NLRP3, NF-κB, and STAT3 through hydrogen bonds, C-H bonds, and electrostatic attractions. In vitro analyses demonstrated that GLEE significantly attenuated NLRP3 inflammasome activation and inhibited the polarization of bone marrow-derived macrophages (BMDMs) towards the M1 phenotype. In vivo, GLEE not only prevented bone mineral density (BMD) loss but also reduced ankle swelling in CIA rats. Furthermore, it decreased the expression of the NLRP3 inflammasome and curtailed the release of inflammatory mediators within the knee joint.

CONCLUSION

GLEE effectively mitigated inflammatory responses in both blood and knee synovial membranes of CIA rats, potentially through the down-regulation of the NLRP3/Caspase-1/IL-1β signaling pathway and reduction in M1 macrophage polarization.

The role of lactylation in plasma cells and its impact on rheumatoid arthritis pathogenesis: insights from single-cell RNA sequencing and machine learning

Introduction

Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by persistent synovitis, systemic inflammation, and autoantibody production. This study aims to explore the role of lactylation in plasma cells and its impact on RA pathogenesis.

Methods

We utilized single-cell RNA sequencing (scRNA-seq) data and applied bioinformatics and machine learning techniques. A total of 10,163 cells were retained for analysis after quality control. Clustering analysis identified 13 cell clusters, with plasma cells displaying the highest lactylation scores. We performed pathway enrichment analysis to examine metabolic activity, such as oxidative phosphorylation and glycolysis, in highly lactylated plasma cells. Additionally, we employed 134 machine learning algorithms to identify seven core lactylation-promoting genes and constructed a diagnostic model with an average AUC of 0.918.

Results

The RA lactylation score (RAlac_score) was significantly elevated in RA patients and positively correlated with immune cell infiltration and immune checkpoint molecule expression. Differential expression analysis between two plasma cell clusters revealed distinct metabolic and immunological profiles, with cluster 2 demonstrating increased immune activity and extracellular matrix interactions. qRT-PCR validation confirmed that NDUFB3, NGLY1, and SLC25A4 are highly expressed in RA.

Conclusion

This study highlights the critical role of lactylation in plasma cells for RA pathogenesis and identifies potential biomarkers and therapeutic targets, which may offer insights for future therapeutic strategies.

Integration of single-cell and bulk RNA sequencing revealed immune heterogeneity and its association with disease activity in rheumatoid arthritis patients

Rheumatoid arthritis (RA) is a chronic, inflammatory, systemic autoimmune disease characterized by cartilage, bone damage, synovial inflammation, hyperplasia, autoantibody production, and systemic features. To obtain an overall profile of the immune environment in RA patients and its association with clinical features, we performed single-cell transcriptome and T-cell receptor sequencing of mononuclear cells from peripheral blood (PBMC) and synovial fluid (SF) from RA patients, integrated with two large cohorts with bulk RNA sequencing for further validation and investigation. Dendritic cells (DCs) exhibited relatively high functional heterogeneity and tissue specificity in relation to both antigen presentation and proinflammatory functions. Peripheral helper T cells (TPHs) are likely to originate from synovial tissue, undergo activation and exhaustion, and are subsequently released into the peripheral blood. Notably, among all immune cell types, TPHs were found to have the most intense associations with disease activity. In addition, CD8 effector T cells could be clustered into two groups with different cytokine expressions and play distinct roles in RA development. By integrating single-cell data with bulk sequencing from two large cohorts, we identified interactions among TPHs, CD8 cells, CD16 monocytes, and DCs that strongly contribute to the proinflammatory local environment in RA joints. Of note, the swollen 28-joint counts exhibited a more pronounced association with this immune environment compared to other disease activity indexes. The immune environment alternated significantly from PBMCs to SF, which indicated that a series of immune cells was involved in proinflammatory responses in the local joints of RA patients. By integrating single-cell data with two large cohorts, we have uncovered associations between specific immune cell populations and clinical features. This integration provides a rapid and precise methodology for assessing local immune activation, offering valuable insights into the pathophysiological mechanisms at play in RA.

N6‑methyladenosine methyltransferase METTL14 is associated with macrophage polarization in rheumatoid arthritis

Rheumatoid arthritis (RA) is largely caused by the inflammatory response triggered by macrophage polarization. Through epigenetic reprogramming, the inflammatory state of macrophages can be modified. Macrophage polarization is associated with the RNA epigenetic alteration N6-methyladenosine (m6A) RNA methylation. However, the specific function and underlying mechanisms of m6A methylation in the role of macrophage polarization in RA remain to be elucidated. The mRNA expression levels of m6A methylase genes and signaling pathway components associated with RA macrophages were determined in the present study using reverse-transcription quantitative PCR. Methyltransferase 14 (METTL14) protein expression levels were determined using western blot analysis, and the levels of specific cellular secretion factors were determined using ELISA and flow cytometry. The results of the present study demonstrated that elevated METTL14 expression was associated with joint tenderness, and METTL14 expression was positively correlated with both C-reactive protein and rheumatoid factor expression levels. Moreover, METTL14 exhibited potential in the prediction of visual analogue scale. Pro-inflammatory cytokines (TNF-α) and M1 macrophage markers (CD68+CD86+) were also positively associated with METTL14 expression. The results of the Kyoto Encyclopedia of Genes and Genomes analysis revealed that METTL14 was strongly associated with the MAPK signaling pathway. Notably, JNK and ERK2 exhibited a positive correlation with the M1 macrophage marker, CD68+CD86+, which was positively associated with the pro-inflammatory factor, TNF-α. JNK and ERK2 expression levels were markedly increased in the METTL14 high-expression group, compared with in the low-expression group; however, p38 and ERK1 expression levels were not significantly different between these groups. Collectively, the results of the present study demonstrated that METTL14 expression was significantly increased in the peripheral blood and synovial tissue of patients with RA, highlighting the potential association with both immunoinflammatory markers and clinical symptoms. In addition, it was suggested that METTL14 may exacerbate the downstream inflammatory response, through mediating macrophage polarization via the MAPK pathway.

Unlocking the Future: New Biologic Therapies for Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disorder that leads to joint destruction and functional disability. Traditional treatments, including disease-modifying antirheumatic drugs (DMARDs), often fail, leaving many patients without remission. The advent of biologic therapies that target specific immune system components (e.g., cytokines, T cells) has transformed RA treatment by offering new management options. These biologics (e.g., TNF inhibitors, interleukin blockers) are highly effective in controlling disease activity and preventing joint destruction. However, their use comes with safety concerns, particularly regarding immunosuppression and infection risks. Although still experimental, studies predict that future research will focus on enhancing the clinical response and safety of these agents through personalized approaches or novel mechanisms of action.

Saccharomyces boulardii (CNCM I-745) alleviates collagen-induced arthritis by partially maintaining intestinal mucosal integrity through TLR2/MYD88/NF-κB pathway inhibition

BACKGROUND

Rheumatoid arthritis, a condition characterized by inflammation, has a substantial influence on both the worldwide economy and public health. Prior studies indicate that probiotics have the potential to enhance the composition of gut microbiota in instances of intestinal dysbiosis resulting from different disorders and contribute to the regulation of inflammation. The objective of this study is to investigate the impact of Saccharomyces boulardii on the gut microbiome in arthritis and its implications on inflammation.

METHODS

The study utilized the Collagen Induced Arthritis (CIA) Sprague-Dawley (SD) rat model. After administering Saccharomyces boulardii (150 mg/kg/day) six days a week and Methotrexate (MTX) (0.2 mg/week) treatment for eight weeks, microbial DNA from the feces was sequenced using 16S rRNA. The evaluation of histopathology, bone loss, and cartilage degradation was conducted using histology, immunohistology assays, and micro-computed tomography (µCT) examinations. The enzyme-linked immunosorbent assay (ELISA) was used to analyze proinflammatory cytokines, while the western blot technique was applied to detect protein in the gut and in cell lines. The quantification of gene expression in gut,joint and cell lines was performed using real-time polymerase chain reaction. The cell lines were activated and then treated with the culture supernatant of S. boulardii for an in vitro investigation. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test was utilized to assess cell proliferationand viability. Cellular motility was measured in a wound healing experiment, whereas apoptotic proteins were analyzed using Western blotting.

RESULTS

S. boulardii has been found to enhance bone and joint integrity, modulate gut microbiota, and mitigate proinflammatory cytokine levels in rats with arthritis. It decreases the permeability of the intestines and promotes the production of gut tight-junction proteins. The administration of S. boulardii inhibits the proliferation of T-helper-17 (Th17) and Type 3 innate lymphoid cells (ILC3). Additionally, it elicits apoptosis in MH7A cell lines and hinders their migratory activity.

CONCLUSION

This study provides valuable insights into the therapeutic potential of S. boulardii for treating and preventing arthritis in rats with collagen-induced arthritis by modulating gut microbiota and inflammation.

Characteristics of PD-1+CD4+ T cells in peripheral blood and synovium of rheumatoid arthritis patients

Objectives

PD-1 plays a crucial role in the immune dysregulation of rheumatoid arthritis (RA), but the specific characteristics of PD-1+CD4+ T cells remain unclear and require further investigation.

Methods

Circulating PD-1+CD4+ T cells from RA patients were analysed using flow cytometry. Plasma levels of soluble PD-1 (sPD-1) were measured using enzyme-linked immunosorbent assay (ELISA). Single-cell RNA sequence data from peripheral blood mononuclear cells (PBMCs) and synovial tissue of patients were obtained from the GEO and the ImmPort databases. Bioinformatics analyses were performed in the R studio to characterise PD-1+CD4+ T cells. Expression of CCR7, KLF2 and IL32 in PD-1+CD4+ T cells was validated by flow cytometry.

Results

RA patients showed an elevated proportion of PD-1+CD4+ T cells in peripheral blood, along with increased plasma sPD-1 levels, which positively correlated with TNF-α and erythrocyte sedimentation rate. Bioinformatic analysis revealed PD-1 expression on CCR7+CD4+ T cells in PBMCs, and on both CCR7+CD4+ T cells and CXCL13+CD4+ T cells in RA synovium. PD-1 was co-expressed with CCR7, KLF2, and IL32 in peripheral CD4+ T cells. In synovium, PD-1+CCR7+CD4+ T cells had higher expression of TNF and LCP2, while PD-1+CXCL13+CD4+ T cells showed elevated levels of ARID5A and DUSP2. PD-1+CD4+ T cells in synovium also appeared to interact with B cells and fibroblasts through BTLA and TNFSF signalling pathways.

Conclusion

This study highlights the increased proportion of PD-1+CD4+ T cells and elevated sPD-1 levels in RA. The transcriptomic profiles and signalling networks of PD-1+CD4+ T cells offer new insights into their role in RA pathogenesis.

Targeting Lactate: An Emerging Strategy for Macrophage Regulation in Chronic Inflammation and Cancer

Lactate accumulation and macrophage infiltration are pivotal features of both chronic inflammation and cancer. Lactate, once regarded merely as an aftereffect of glucose metabolism, is now gaining recognition for its burgeoning spectrum of biological roles and immunomodulatory significance. Recent studies have evidenced that macrophages display divergent immunophenotypes in different diseases, which play a pivotal role in disease management by modulating macrophage polarization within the disease microenvironment. The specific polarization patterns of macrophages in a high-lactate environment and their contribution to the progression of chronic inflammation and cancer remain contentious. This review presents current evidence on the crosstalk of lactate and macrophage in chronic inflammation and cancer. Additionally, we provide an in-depth exploration of the pivotal yet enigmatic mechanisms through which lactate orchestrates disease pathogenesis, thereby offering novel perspectives to the development of targeted therapeutic interventions for chronic inflammation and cancer.

ITIH4 in Rheumatoid Arthritis Pathogenesis: Network Pharmacology and Molecular Docking Analysis Identify CXCR4 as a Potential Receptor

Elevated levels of Inter-alpha-trypsin-inhibitor heavy chain 4 (ITIH4) have grabbed attention in rheumatoid arthritis (RA) pathogenesis, though its precise mechanisms remain unexplored. To elucidate these mechanisms, a comprehensive strategy employing network pharmacology and molecular docking was utilized. RA targets were sourced from the DisGeNET Database while interacting targets of ITIH4 were retrieved from the STRING and Literature databases. Venny 2.1 was used to identify overlapping genes, followed by Gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) through Cytoscape 3.10.2 software, and molecular docking was performed in the ClusPro server. The study identified 18 interacting proteins of ITIH4 associated with RA, demonstrating their major involvement in the chemokine signaling pathway by enrichment analysis. Molecular docking of ITIH4 with the 18 proteins revealed that C-X-C chemokine-receptor type 4 (CXCR4), a major protein associated with chemokine signaling, has the highest binding affinity with ITIH4 with energy -1705.7 kcal/mol forming 3 Hydrogen bonds in the active site pocket of ITIH4 with His441, Arg288, Asp443 amino acids. The effect of ITIH4 on CXCR4 was analyzed via knockdown studies in rheumatoid arthritis fibroblast-like synoviocytes (RA-FLS), demonstrating the significant downregulation of CXCR4 protein expression validated by Western blot in RA-FLS. In conclusion, it was speculated that CXCR4 might serve as a potential receptor for ITIH4 to activate the chemokine signaling, exacerbating RA pathogenesis.