Origins of rheumatoid arthritis

Neutrophil extracellular traps: Potential targets for the treatment of rheumatoid arthritis with traditional Chinese medicine and natural products

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease. Abnormal formation of neutrophil extracellular traps (NETs) at the synovial membrane leads to the release of many inflammatory cytokines, including IL-1β, IL-6, and TNF-α. Elastase, histone H3, and myeloperoxidase, which are carried by NETs, damage the soft tissues of the joints and aggravate the progression of RA. The balance of NET formation coordinates the pro-inflammatory and anti-inflammatory effects and plays a key role in the development of RA. Therefore, when NETs are used as effector targets, highly targeted drugs with fewer side effects can be developed to treat RA without damaging the host immune system. Currently, an increasing number of studies have shown that traditional Chinese medicines and natural products can regulate the formation of NETs through multiple pathways to counteract RA, which shows great potential for the treatment of RA and has a promising future for clinical application. In this article, we review the latest biological progress in understanding NET formation, the mechanism of NETs in RA, and the potential targets or pathways related to the modulation of NET formation by Chinese medicines and natural products. This review provides a relevant basis for the use of Chinese medicines and natural products as natural adjuvants in the treatment of RA.

Deciphering Autoimmune Diseases: Unveiling the Diagnostic, Therapeutic, and Prognostic Potential of Immune Repertoire Sequencing

Autoimmune diseases (AIDs) are immune system disorders where the body exhibits an immune response to its own antigens, causing damage to its own tissues and organs. The pathogenesis of AIDs is incompletely understood. However, recent advances in immune repertoire sequencing (IR-seq) technology have opened-up a new avenue to study the IR. These studies have revealed the prevalence in IR alterations, potentially inducing AIDs by disrupting immune tolerance and thereby contributing to our comprehension of AIDs. IR-seq harbors significant potential for the clinical diagnosis, personalized treatment, and prognosis of AIDs. This article reviews the application and progress of IR-seq in diseases, such as multiple sclerosis, systemic lupus erythematosus, rheumatoid arthritis, and type 1 diabetes, to enhance our understanding of the pathogenesis of AIDs and offer valuable references for the diagnosis and treatment of AIDs.

Evaluation of Choroidal Thickness and Choroidal Vascularity Index in Patients with Rheumatoid Arthritis

PURPOSE

To evaluate the choroidal vascularity index and choroidal thickness in patients with rheumatoid arthritis.

METHOD

This study is a case control study. Our study consists of a total of two groups, with 32 individuals diagnosed with rheumatoid arthritis (RA) and 32 healthy volunteers. The thickness of the subfoveal choroid was measured from the 500 micron (µm), 1000 µm, 1500 µm nasal aspect of the fovea, and 500µm, 1000µm, 1500 µm temporal and subfoveal thickness of the fovea. ImageJ version 1.53i (National Institutes of Health, Bethesda, MD, USA) from open access was used for choroidal vascular index calculation.

RESULTS

The mean age (p = 0.064) and gender distribution (p = 0.522) were not statistically different between these two groups. There was no difference between the groups in terms of visual acuity (p = 0.060), intraocular pressures (p=0.056), refractive errors (p = 0.418), and axial lengths (p = 0.280). Temporal 500 µm CT (p = 0.038), temporal 1000 µm CT (p = 0.010), and temporal 1500 µm CT (p = 0.005) differed significantly between the groups. The luminal area was significantly different between the RA group (842.71 ± 192.77) and the control group (957.78 ± 230.83) (p = 0.034). The choroidal vascularity index showed a significant difference between the RA group (64.99 ± 4.71) and the control group (67.34 ± 3.40) (p = 0.026). A significant difference was observed between the seronegative RA and the control group with temporal 1500 µm CT (p = 0.030), temporal 1000 µm CT (p = 0.023), and luminal area (p = 0.034).

CONCLUSION

We demonstrated thinning in CT and decreased CVI for the first time in RA patients by comparing it with the control group.

Identification of HHT-9041P1: A novel potent and selective JAK1 inhibitor in a rat model of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic systemic disease associated with long-term disability and premature mortality. If left untreated, it can seriously affect patients' quality of life. The JAK-STAT signal transduction process is known to affect the occurrence and development of RA, and small molecule JAK inhibitors, such as tofacitinib, have been identified as treatments for RA. However, tofacitinib is a non-selective JAK inhibitor that was found to be associated with dose-limiting tolerability and safety issues, such as anemia in phase 2 dose-ranging studies. Therefore, we developed a selective JAK1 inhibitor, HHT-9041P1, to overcome target-related adverse reactions. We used enzyme and cytokine potency assays in vitro as well as the collagen-induced arthritis (CIA) model in vivo to explore the efficacy and mechanism. In vitro, HHT-9041P1 was diluted (0.017 nM-1 mM) in DMSO) and mixed with JAK1, JAK2, JAK3 or TYK2 kinases for use in the respective assays for inhibitory activity and selectivity evaluation. Fresh human PBMCs were activated and incubated with 100 ng/mL cytokine IL-6 or 20 ng/mL GM-CSF for use in the investigation of the immune mechanism. In vivo, HHT-9041P1 (1 mg/kg, 3 mg/kg and 10 mg/kg) was administered by oral gavage twice daily to CIA model Lewis rats from Day 8 to Day 29 for paw swelling and arthritis score evaluation. At the end of the experiment, the rats were sacrificed before collection of the hind ankle joint, spleen and blood for analysis of inflammation, arthritis phenotypes, inflammatory cytokine expression and Th1 cell proportions. As expected, HHT-9041P1 showed 10-fold greater selectivity for JAK1 over JAK2, and 23-fold greater selectivity over JAK3 in cellular assays. The high selectivity of HHT-9041P1 was also validated by in vivo safety studies. HHT-9041P1 demonstrated significant efficacy in a rat model of collagen-induced arthritis (CIA) and was associated with reduced helper T Cell 1 (Th1) cell differentiation. HHT-9041P1 also exhibited excellent pharmacokinetics properties. Thus, HHT-9041P1 was identified as a candidate for clinical development with many options for the treatment of RA.

Appraising the causal relationship between thyroid function and rheumatoid arthritis: a two-sample bidirectional Mendelian randomization study

Background

Hypothyroidism and hyperthyroidism are observationally associated with rheumatoid arthritis (RA), but causality is unclear. To evaluate the causal relationship between thyroid function and RA, we conducted a two-Sample bidirectional Mendelian Randomization (MR) study.

Methods

Single nucleotide polymorphisms associated with six phenotypes were selected from the FinnGen biobank database, The ThyroidOmics Consortium database, and the IEU Open GWAS database. For the forward MR analysis, we selected hypothyroidism (N=213,390), Graves' disease (GD) (N=199,034), other types of hyperthyroidism (N=190,799), free thyroxine (FT4, N=49,269), and thyroid-stimulating hormone (TSH, N=54,288) as the five related thyroid function phenotypes for exposure, with RA (N=58,284) as the outcome. Reverse MR analysis selected RA as the exposure and five phenotypes of thyroid function as the outcome. The Inverse variance weighting (IVW) method was used as the primary analysis method, supplemented by weighted median (WM) and MR-Egger methods. Cochran's Q test, MR-PRESSO, MR-Egger regression methods, and leave-one-out analysis were employed to assess sensitivity and pleiotropy.

Results

Forward MR evidence indicates that genetic susceptibility to hypothyroidism is associated with an increased risk of RA (ORIvw=1.758, P=7.61×10-5). Reverse MR evidence suggests that genetic susceptibility to RA is associated with an increased risk of hypothyroidism (ORIvw=1.274, P=3.88×10-20), GD (ORIvw=1.269, P=8.15×10-05), and other types of hyperthyroidism (ORIvw=1.141, P=1.80×10-03). There is no evidence to support a forward or reverse causal relationship between genetic susceptibility to RA and FT4, TSH.

Conclusion

Our results provide genetic evidence supporting bidirectional causal relationships between thyroid function and RA. These findings inform preventive strategies and interventions targeting RA and thyroid dysfunction.

Analyzation of the Peripheral Blood Mononuclear Cells Atlas and Cell Communication of Rheumatoid Arthritis Patients Based on Single-Cell RNA-Seq

Background

Rheumatoid arthritis (RA) is a common chronic inflammatory autoimmune disease with a multifactorial etiology. Peripheral blood is the main channel of the immune system, and peripheral blood mononuclear cells (PBMCs) are the immune cells that initiate the autoimmune inflammatory process. However, there are few reports on the mechanisms of peripheral blood immunity in RA.

Methods

ScRNA-seq was performed on four RA samples and integrated with single-cell transcriptome data from four healthy control samples downloaded from publicly available databases for analysis.

Results

A total of 52,073 cells were used for descending clustering analysis to map RA peripheral blood immune cells at single-cell resolution. Redimensional clustering analysis of four major immune cells (T cells, monocytes, B cells, and natural killer cells) revealed that double-negative T (DNT) cells were significantly altered in abundance and function. And a number of genes (including SOCS3, cAMP-responsive element modulator (CREM), B2M, MTFP1, RSRP1, and YWHAB) were specifically downregulated in DNT cells. RA T cells, especially DNT cells, exhibit significant metabolic defects and dysfunction, mainly in the form of inhibition of oxidative phosphorylation, ATP synthesis, and major histocompatibility complex (MHC)-I-mediated antigen presentation. In addition, cellular communication networks were established, and it was evident that RA is significantly attenuated in the number and intensity of cellular communication. Monocytes and T cells play key roles in the process of the immune inflammatory response through CCL and MHC-related pathways.

Conclusions

This study describes the landscape of the peripheral blood immune system and cell communication in RA, characterizes the abundance of PBMCs, gene expression profiles, and changes in signaling pathways in RA patients, and identifies several key cell subpopulations (DNT and classic monocytes) and specific genes (SOCS3, CREM, B2M, MTFP1, RSRP1, and YWHAB). Meanwhile, we propose that classic monocytes in peripheral blood may migrate to sites of inflammation in synovial tissue under the chemotaxis of the chemokines CCL3 and CCL3L1, differentiate into macrophages, secrete proinflammatory cytokines, and thus participate in the inflammatory response. These findings provide new insights for the future elucidation of the peripheral blood immune mechanisms of RA and the search for new clinical therapeutic targets.

The exposure to volatile organic chemicals associates positively with rheumatoid arthritis: a cross-sectional study from the NHANES program

Introduction

Rheumatoid arthritis (RA) is an autoimmune disease and closely associated with both genetic and environmental factors. Volatile organic chemicals (VOC), a common environment pollutant, was associated with some autoimmune diseases, while whether VOC exposure or which VOC leads to RA is yet clarified.

Methods

A cross-sectional study using data from the 6 survey cycles (2005-2006, 2011-2012, 2013-2014, 2015-2016, 2017-2018, 2017-2020) of NHANES program was performed. The RA or non-arthritis status of participant was identified through a questionnaire survey. The quantile logistic regression method was used for correlation analysis between VOC metabolites (VOCs) in urine and RA. The covariates included age, gender, race, educational level, marital status, total energy intake, physical activity, smoking, hypertension, diabetes, urine creatinine, albumin and marihuana use.

Results

A total of 9536 participants (aged 20 to 85) with 15 VOCs, comprising 618 RA and 8918 non-arthritis participants, was finally included for analysis. Participants in the RA group showed higher VOCs in urine than that in the non-arthritis group. A positive association between 2 VOCs (AMCC: Q4: OR=2.173, 95%CI: 1.021, 4.627. 3HPMA: Q2: OR=2.286, 95%CI: 1.207 - 4.330; Q4: OR=2.663, 95%CI: 1.288 -5.508.) and RA was detected in the model 3, which was independent of all the covariates. The relative parent compounds of the two VOCs included N,N-Dimethylformamide and acrolein.

Discussion

These findings suggested that the VOC exposure significantly associated with RA, providing newly epidemiological evidence for the establishment that environmental pollutants associated with RA. And also, more prospective studies and related experimental studies are needed to further validate the conclusions of this study.

Computational Fluid Dynamics (CFD) Model for Analysing the Role of Shear Stress in Angiogenesis in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterised by an attack on healthy cells in the joints. Blood flow and wall shear stress are crucial in angiogenesis, contributing to RA's pathogenesis. Vascular endothelial growth factor (VEGF) regulates angiogenesis, and shear stress is a surrogate for VEGF in this study. Our objective was to determine how shear stress correlates with the location of new blood vessels and RA progression. To this end, two models were developed using computational fluid dynamics (CFD). The first model added new blood vessels based on shear stress thresholds, while the second model examined the entire blood vessel network. All the geometries were based on a micrograph of RA blood vessels. New blood vessel branches formed in low shear regions (0.840-1.260 Pa). This wall-shear-stress overlap region at the junctions was evident in all the models. The results were verified quantitatively and qualitatively. Our findings point to a relationship between the development of new blood vessels in RA, the magnitude of wall shear stress and the expression of VEGF.

Protocatechuic acid reduces H2O2-induced migration and oxidative stress of fibroblast-like synoviocytes in rheumatoid arthritis by activating Nrf2-Keap1 signaling pathway

Honeycomb (Nidus vespae) is traditional Chinese medicine and can treat rheumatoid arthritis (RA), and protocatechuic acid (PCA) is a bioactive component of honeycomb. This study aimed to investigate whether PCA could reduce the H₂O₂-induced migration and oxidative stress of RA fibroblast-like synoviocytes (RA-FLSs). H₂O₂-induced RA-FLSs were used to simulate the in vitro model of RA. The viability, apoptosis, migration, invasion, and oxidative stress of RA-FLSs were detected by Cell Counting Kit-8 (CCK-8), terminal deoxynucleotidyl transferase dUTP nick-end labeling assay, wound healing, transwell assays, DCFDA staining, and malonaldehyde and superoxide dismutase enzyme-linked immunosorbent assay kits. The expression of migration and invasion-related proteins and Nrf2/Keap1 signaling pathway-related proteins was analyzed by western blotting. As a result, PCA suppressed the viability, migration, invasion, and oxidative and promoted apoptosis of H₂O₂-induced RA-FLSs by activating the Nrf2/Keap1 signaling pathway. ML-385, an Nrf2 inhibitor, could enhance the viability, migration, invasion, and oxidative and inhibited apoptosis of H₂O₂-induced RA-FLSs. In conclusion, PCA reduced H₂O₂-induced migration and oxidative stress of RA-FLSs by activating the Nrf2-Keap1 signaling pathway.

Self-reported and genetically predicted effects of coffee intake on rheumatoid arthritis: Epidemiological studies and Mendelian randomization analysis

Background and aims

Causal research concerning coffee intake and rheumatoid arthritis (RA) risk is controversial. The objective of this study was to further explore the causal relationship between coffee intake and RA risk.

Methods

The 4,310 participants from NHANES 2003–2006 were included in an epidemiological study to assess the association between coffee intake and RA by weighted multivariate logistic regression. The inverse variance weighted (IVW) method of two-sample Mendelian randomization (MR), employing genetic data from UK Biobank (428,860 cases) of coffee intake and MR-Base platform (14,361 cases and 43,923 controls) of RA, was performed to estimate the causal relationship between coffee intake and RA.

Results

Weighted multivariate logistic regression suggested no significant correlation between coffee intake and RA. Compared to the no-coffee group, the odds ratio for RA in the <1, 1–3, ≥4 cups/day group were 1.297, 1.378, and 1.125 (P = 0.204, 0.098, and 0.698, respectively). In the IVW of MR analysis, there was no causal relationship between coffee intake and RA (OR = 1.47, P = 0.218).

Conclusion

Our study did not support a causal association between coffee intake and RA risk. However, it is necessary to consider valid information on coffee intake, including brewing method, type of coffee, and quantity, in further analysis of coffee intake and RA.

Serum Fatty Acid Profiles Are Associated with Disease Activity in Early Rheumatoid Arthritis: Results from the ESPOIR Cohort

Background: Long-chain omega-3 and omega-6 fatty acids (n-3, n-6 FAs) may modulate inflammation and affect the risk of developing rheumatoid arthritis (RA). However, whether n-3/n-6 FA status affects RA after disease onset is unknown. This study aimed to assess whether FA profiles are independently associated with disease activity in a large prospective cohort of patients with early RA. Methods: Baseline serum FAs were quantified in 669 patients in the ESPOIR cohort. Principal component analysis identified three serum FA patterns that were rich in n-7–9, n-3 and n-6 FAs (patterns ω7–9, ω3 and ω6), respectively. The association of pattern tertiles with baseline variables and 6-month disease activity was tested using multivariable logistic regression. Results: Pattern ω3 was associated with low baseline and pattern ω6 with high baseline C-reactive protein level and disease activity. Both patterns ω3 and ω6 were associated with reduced odds of active disease after 6 months of follow-up (pattern ω3: odds ratio, tertile three vs. one, 0.49 [95% CI 0.25 to 0.97] and pattern ω6: 0.51 [0.28 to 0.95]; p = 0.04 and 0.03, respectively). Conclusions: In a cohort of early RA patients, a serum lipid profile rich in n-3 FAs was independently associated with persistently reduced disease activity between baseline and 6-month follow-up. An n-6 FA profile was also associated with lower 6-month disease activity.

Recent Findings on Thymoquinone and Its Applications as a Nanocarrier for the Treatment of Cancer and Rheumatoid Arthritis

Cancer causes a considerable amount of mortality in the world, while arthritis is an immunological dysregulation with multifactorial pathogenesis including genetic and environmental defects. Both conditions have inflammation as a part of their pathogenesis. Resistance to anticancer and disease-modifying antirheumatic drugs (DMARDs) happens frequently through the generation of energy-dependent transporters, which lead to the expulsion of cellular drug contents. Thymoquinone (TQ) is a bioactive molecule with anticancer as well as anti-inflammatory activities via the downregulation of several chemokines and cytokines. Nevertheless, the pharmacological importance and therapeutic feasibility of thymoquinone are underutilized due to intrinsic pharmacokinetics, including short half-life, inadequate biological stability, poor aqueous solubility, and low bioavailability. Owing to these pharmacokinetic limitations of TQ, nanoformulations have gained remarkable attention in recent years. Therefore, this compilation intends to critically analyze recent advancements in rheumatoid arthritis and cancer delivery of TQ. This literature search revealed that nanocarriers exhibit potential results in achieving targetability, maximizing drug internalization, as well as enhancing the anti-inflammatory and anticancer efficacy of TQ. Additionally, TQ-NPs (thymoquinone nanoparticles) as a therapeutic payload modulated autophagy as well as enhanced the potential of other drugs when given in combination. Moreover, nanoformulations improved pharmacokinetics, drug deposition, using EPR (enhanced permeability and retention) and receptor-mediated delivery, and enhanced anti-inflammatory and anticancer properties. TQ's potential to reduce metal toxicity, its clinical trials and patents have also been discussed.

Influence of HLA Class II Alleles and DRB1-DQB1 Haplotypes on Rheumatoid Arthritis Susceptibility and Autoantibody Status in the Chinese Han Population

Human leukocyte antigen (HLA) class II alleles are considered to play a key role in the progress of rheumatoid arthritis (RA). This study was carried out to investigate the presence of HLA class II alleles and their influence on disease risk and autoantibody status in Chinese Han patients with RA. Here, HLA-DRB1, DQB1 and DPB1 genotyping was performed in 125 RA patients and 120 healthy controls by using the next-generation sequencing (NGS). Strong positive associations were shown between high-resolution typed HLA-DRB1*04:05:01, DRB1*10:01:01, DQB1*04:01:01, DPB1*02:01:02 and RA patients. Moreover, the haplotypes HLA-DRB1*04:05:01~ DQB1*04:01:01 and HLA-DRB1*10:01:01~ DQB1*05:01:01 were found to be more frequent in RA populations than in healthy controls. These possible susceptible HLA alleles (HLA-DRB1*04:05:01, DRB1*10:01:01, DQB1*04:01:01 and DPB1*02:01:02) also showed higher frequencies in seropositive RA patients as compared to normal controls. The present study provided evidence that alleles HLA-DRB1*04:05:01, DRB1*10:01:01, DQB1*04:01:01 and DPB1*02:01:02 constituted RA risk alleles, and haplotypes HLA-DRB1*04:05:01~ DQB1*04:01:01, HLA-DRB1*10:01:01~ DQB1*05:01:01 also showed prevalence in Chinese Han patients with RA. Serological results preliminary demonstrated patients carrying RA-risk HLA alleles might elevate the serum level of anti-citrullinated protein antibodies and rheumatoid factor and affect RA progression.

Antigen-specific tolerance approach for rheumatoid arthritis: Past, present and future

Rheumatoid arthritis is a chronic systemic autoimmune disease, affecting mainly the joints. It is caused by an adaptive immune reaction against self-antigens, leading to the over production of inflammatory cytokines and autoantibodies, mainly mediated by autoreactive CD4+ T cells and pathological B cell clones. The treatment options currently available rely on palliative global immunosuppression and do not restore tolerance to self-components. Here, we review antigen-specific tolerance approaches that have been developed to inhibit or delete autoreactive clones, while maintaining a potent immune system for rheumatoid arthritis. The first attempts relied on the oral ingestion of self-reactive peptides, with lukewarm results in human clinical trials. To enhance treatment efficacy, self-peptides have been engineered and combined with immunosuppressive molecules. In addition, several routes of delivery have been tested, in particular, nanoparticles carrying self-antigens and immunomodulatory molecules. More recently, transfer of immune cells, such as tolerogenic dendritic cells or regulatory T cells, has been considered to restore tolerance. Although promising results have been obtained in mouse models, the translation to humans remains highly challenging, mainly because the disease is already well developed when treatments start and because patient's specific self-antigens are often unknown. Nevertheless, these approaches hold great promises for long-term RA treatment.

New insights into macrophage heterogeneity in rheumatoid arthritis

Rheumatoid arthritis (RA) is a prototypic autoimmune disease that primarily affects joints. Clinical studies and animal models evidenced that mononuclear phagocytes including monocytes and macrophages are crucial to RA pathogenesis, contributing to inflammation and destruction of cartilage and bone. The last decade of research has tremendously changed our view on the origin of tissue-resident macrophages. In light of the recent publications that reveal important phenotypic and functional heterogeneity among macrophages, it is of paramount importance to identify the synovial macrophage subsets that might amplify the inflammatory response or promote the restoration of tissue homeostasis. In this review, we highlight latest studies applying single-cell RNA sequencing that provide deeper insights in macrophage subsets and their putative functions within both human and mouse synovial joint tissue.