Age-related self-DNA accumulation may accelerate arthritis in rats and in human rheumatoid arthritis

Immunosenescence in autoimmune diseases

Autoimmune diseases (AIDs) are a group of disorders in which the immune system mistakenly attacks the body's own tissues, characterized by the loss of tolerance to self-antigens and destruction of tissues. Aging is a natural process of physiological decline that also alters the immune system, a condition known as immunosenescence. During immunosenescence, the immune system undergoes various changes, including modifications and antigenicity of self-antigens, abnormalities in the quantity, phenotype, and function of lymphocytes and antibodies, as well as a narrowing of the B and T cell receptor repertoire, changes that may increase susceptibility to AIDs. Additionally, senescent immune cells and the senescence-associated secretory phenotype (SASP) contribute to target organ involvement in AIDs, exacerbating chronic inflammation and tissue damage. Mitochondrial dysfunction and metabolic imbalances in AIDs lead to the accumulation of senescent cells, which act as upstream drivers of immunosenescence. In this review, we summarize the bidirectional relationship between AIDs and immunosenescence, as well as its potential mechanisms. Therapeutic approaches targeting immunosenescence in AIDs remain at an early stage. Strategies aimed at resetting or reversing the aging immune system are expected to become a novel direction in the future.

Cell-free DNA-scavenging nano/microsystems for immunotherapy

In the context of inflammation, autoimmune diseases, infections, and cancers, cfDNA plays a pivotal role in disease progression through various mechanisms. Immunotherapies based on cfDNA scavenging has emerged as a promising approach for treating these conditions. This review offers a comprehensive exploration of cfDNA-binding and degradation strategies, providing detailed insights into the corresponding nano/microsystems for each approach. Nano/microsystems used for cfDNA binding include cationic polymers, nanoparticles, nanogels, and other materials that physically capture cfDNA via electrostatic interactions or other affinity mechanisms, thereby mitigating the immunological effects of cfDNA. Nano/microsystems designed for cfDNA degradation primarily involve DNase delivery systems and artificial enzymes with DNase-like activity, which degrade cfDNA through chemical cleavage. Furthermore, this review discusses the potential synergy between cfDNA-scavenging therapies and other treatment modalities, aiming to achieve more effective and comprehensive immunotherapy. By thoroughly analyzing these strategies, we aim to emphasize the transformative potential of cfDNA-scavenging nano/microsystems in advancing immunotherapy, and offer valuable perspectives for future research in this emerging field.

SLAM receptors regulate immune checkpoints via SAP and EAT- 2 in rheumatoid arthritis: association with disease activity

OBJECTIVE

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation and immune dysregulation. This study aimed to investigate the role of SLAM family receptors (SLAMF1 and SLAMF7), immune checkpoint molecules (PD- 1 and TIGIT), and SH2-containing adaptor proteins (SAP and EAT- 2) in rheumatoid arthritis (RA) and their association with disease activity.

METHODS

A total of 50 RA patients (30 inactive, 20 active) and 20 healthy controls were enrolled. Real-time ​polymerase chain reaction (PCR) was used to assess the expression of target genes in peripheral blood mononuclear cells (PBMCs). Gene expression profiling datasets (GSE77298, GSE206848, GSE236924, GSE15573) were analyzed to identify differentially expressed genes (DEGs). Correlation of gene expression with Disease Activity Score 28-joint count (DAS28) was evaluated.

RESULTS

SLAMF1, SLAMF7, SAP, and EAT- 2 expression levels were significantly elevated in RA patients compared to controls. SLAMF1 and SAP expression correlated positively with DAS28 (r = 0.319, p = 0.02; r = 0.460, p = 0.0008, respectively). PD- 1 expression was higher in RA patients but showed no correlation with DAS28, while TIGIT expression was not significantly different. Bioinformatics analysis revealed significant upregulation of SLAMF7 and TIGIT in synovial tissues from RA patients.

CONCLUSION

SLAMF1 and SLAMF7 appear to contribute to RA pathogenesis by modulating immune cell activity and cytokine production. Elevated PD- 1 levels suggest a role in immune dysregulation. The interplay between SLAM receptors, immune checkpoints, and adaptor proteins may exacerbate T cell overactivity and chronic inflammation, offering potential therapeutic targets. Key Points •RA patients showed significantly higher expression of SLAMF1, SLAMF7, PD- 1, SAP, and EAT- 2 compared to healthy controls. •SLAMF1 and SAP expression correlated with disease activity, with SLAMF1 levels higher in active RA cases. •PD- 1 overexpression suggested immune dysregulation, while TIGIT showed no significant difference in RA patients. •The interplay between SLAM receptors, immune checkpoints, and adaptor proteins may contribute to RA pathogenesis and serve as potential therapeutic targets.

Application of Elastic networks and Bayesian networks to explore influencing factors associated with arthritis in middle-aged and older adults in the Chinese community

Bayesian networks (BNs) are an excellent machine learning algorithm for extensively exploring the influencing factors associated with many diseases. However, few researchers have used BNs to examine the influencing factors associated with arthritis in older adults in the Chinese community. Our aim has been to use BNs to construct a complex network of relationships between arthritis and its related influencing factors and to predict arthritis through Bayesian inference, thereby providing scientific references for its control and prevention. Data were downloaded from the 2015 China Health and Retirement Longitudinal Study (CHARLS) online database, a longitudinal survey of the middle-aged and older adults in China. Twenty-two variables such as smoking, depressive symptoms, age, and joint pain were included in this study. First, Elastic networks (ENs) were used to screen for features closely associated with arthritis, and we subsequently incorporated these features into the construction of the BNs model. We performed structural learning of the BNs based on the taboo algorithm and used the maximum likelihood method for parameter learning of the BNs. In total, 15,764 participants were enrolled in this study, which included 5,076 patients with arthritis. ENs identified 13 factors strongly associated with arthritis. The BNs consisted of 14 nodes and 24 directed edges. Among them, depressive symptoms and age were direct influences on arthritis, whereas gender was an indirect influence on the diseases. BNs graphically visualized the complex network of relationships between arthritis and its influences and predicted the development of arthritis through Bayesian inference. These results were in line with clinical practice. BNs thus have a wide range of application prospects.

The emerging role of vascular endothelial cell-mediated angiogenesis in the imbalance of RA synovial microenvironment and its clinical relevance

Vascular endothelial cells (VEC) play a key role in the occurrence and progression of vascular inflammation. VEC activation secretes powerful inflammatory mediators and aggravates the development of rheumatoid arthritis (RA). Angiogenesis plays a key role in the pathological processes of inflammation and synovial infiltration, driving RA progression. A substantial amount of evidence suggests that the VEC at the inflammatory site of RA is both an active participant and a regulator of the inflammatory process. At present, the research progress of VEC and inflammation in RA is still incomplete. In this review, we summarize the role of VEC and angiogenesis in the development of RA, describe the relevant cells, cytokines and signaling pathways involved in regulation, and provide research clues on the role of post-translational modification (PTMs) in VEC function and angiogenesis in RA, and classify and integrate these mechanisms and therapeutic strategies. This review aims to synthesize current evidence to support the established link between VEC and RA-related pathology, provide a theoretical basis for clinical studies, and provide valuable insights into the development of therapeutic drugs against RA.

X-chromosome-linked miR-542-5p as a key regulator of sex disparity in rats with adjuvant-induced arthritis by promoting Th17 differentiation

BACKGROUND

Studies have indicated that X-linked microRNAs (miRNAs) play a role in the pathogenesis of rheumatoid arthritis (RA) and its gender-specific differences. However, research on specific miRNAs remains limited. This study aims to investigate the possible role of X-linked miR-542-5p in RA pathogenesis and gender differences.

METHODS

We investigated the impact of miR-542-5p on RA pathogenesis and gender differences by manipulating its expression in various rat models.

RESULTS

Our findings revealed a significant overexpression of miR-542-5p in RA patients compared with healthy individuals, with a notable gender difference among RA patients. In vivo experiments confirmed that upregulation of miR-542-5p could accelerate RA pathogenesis. Further analysis showed that the onset of adjuvant-induced arthritis (AIA) in rats exhibited significant gender differences, with more severe clinical phenotypes found in female rats. This may be attributed to their stronger immune responses and elevated levels of miR-542-5p. Subsequent in vitro and in vivo experiments demonstrated that miR-542-5p contributes to the regulation of gender differences in RA pathogenesis by promoting the differentiation of Th17 cells.

CONCLUSIONS

This study offers new insights into the sex-specific nature of RA, suggesting X-linked miR-542-5p as a potential target for both diagnostic and therapeutic purposes. These findings lay the groundwork for the development of gender-specific therapeutic strategies for RA and underscore the importance of gender consideration in RA research.

Relationship between albumin and rheumatoid arthritis: Evidence from NHANES and Mendelian randomization

With the rising incidence of rheumatoid arthritis (RA) and the increasing percentage of serum RF negativity, more and more accurate methods are urgently needed for the early diagnosis and prevention of RA, among which serum albumin (ALB) is closely related to the development of RA, and it is expected to become a new auxiliary diagnostic means, but its relationship with RA is not clear, so the present study aimed to investigate the Causal relationship. In this study, we used a generalized linear model and smoothed curve fitting to comprehensively evaluate the relationship between ALB and RA through the data of ALB and RA in the NHANES database, in addition, we further used inverse variance weighted (IVW) in Mendelian randomization (MR) in conjunction with the other 4 methods to further validate and clarify the causal relationship. The results were also examined for heterogeneity and horizontal pleiotropy to assess whether the results were robust. Finally, we used Bayesian co-localization analysis to clarify that ALB and RA share common genetic loci. In the observational study, after correction for multiple confounders, ALB remained more significantly negatively associated with RA (OR = 0.66, [95% CI = 0.51-0.86], P = .003), and subgroup analyses showed significant negative associations in both men and women (men: OR = 0.67, [95% CI = 0.46-0.99], P = .046; females: OR = 0.66, [95% CI = 0.44-1.00], P = .049). In further MR analysis, IVW: ALB on RA, OR = 0.70 [95% 0.52-0.93], P = .013; RA on ALB, OR = 0.95 [95% CI = 0.93-0.98], P < .001. The results of the MR analyses were in agreement with those of NHANES, which did not share a common genetic locus in co-localization analysis. There is a significant relationship between ALB and RA, and the reduction of ALB may be one of the risk factors for RA, as well as one of the outcomes in the development of RA.

Cytoplasmic DNA and AIM2 inflammasome in RA: where they come from and where they go?

Rheumatoid arthritis is a chronic autoimmune disease of undetermined etiology characterized by symmetric synovitis with predominantly destructive and multiple joint inflammation. Cytoplasmic DNA sensors that recognize protein molecules that are not themselves or abnormal dsDNA fragments play an integral role in the generation and perpetuation of autoimmune diseases by activating different signaling pathways and triggering innate immune signaling pathways and host defenses. Among them, melanoma deficiency factor 2 (AIM2) recognizes damaged DNA and double-stranded DNA and binds to them to further assemble inflammasome, initiating the innate immune response and participating in the pathophysiological process of rheumatoid arthritis. In this article, we review the research progress on the source of cytoplasmic DNA, the mechanism of assembly and activation of AIM2 inflammasome, and the related roles of other cytoplasmic DNA sensors in rheumatoid arthritis.

Elevated mtDNA content in RBCs promotes oxidative stress may be responsible for faster senescence in men

BACKGROUND

Both we and others have found that RBC counts are significantly lower in older compared to younger. However, when gender is factored in, a significant age-related decrease of RBC counts is observed only in men but not in women.

METHODS

qPCR and confocal microscopy were used to detect the presence of mtDNA in RBCs. Flow cytometry and specific inhibitors were used to determine how RBCs uptake cf-mtDNA. The peripheral blood was collected from 202 young adults and 207 older adults and RBC and plasma were isolated. The levels of TLR9+RBCs and apoptotic RBCs after uptake of cf-mtDNA by RBCs were measured by flow cytometry. The kit detects changes in SOD and MDA levels after cf-mtDNA uptake by RBCs. Young RBCs (YR) and old RBCs (OR) from single individuals were separated by Percoll centrifugation.

RESULTS

We found a significant decrease in RBC counts and a significant increase in the RDW with aging only in men. We also found that significantly elevated mtDNA content in RBCs was observed only in men during aging and was not found in women. Further studies demonstrated that RBCs could take up cf-mtDNA via TLR9, and the uptake of mtDNA might lead to a decrease in the RBC number and an increase in RDW due to an increase of oxidative stress.

CONCLUSIONS

The RBC mtDNA content might be a potential marker of RBC aging and the elevated RBC mtDNA content might be the cause of faster senescence in males than females.

The role of cGAS-STING signaling in rheumatoid arthritis: from pathogenesis to therapeutic targets

Rheumatoid arthritis (RA) is a systemic autoimmune disease primarily characterized by erosive and symmetric polyarthritis. As a pivotal axis in the regulation of type I interferon (IFN-I) and innate immunity, the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) signaling pathway has been implicated in the pathogenesis of RA. This pathway mainly functions by regulating cell survival, pyroptosis, migration, and invasion. Therefore, understanding the sources of cell-free DNA and the mechanisms underlying the activation and regulation of cGAS-STING signaling in RA offers a promising avenue for targeted therapies. Early detection and interventions targeting the cGAS-STING signaling are important for reducing the medical burden on individuals and healthcare systems. Herein, we review the existing literature pertaining to the role of cGAS-STING signaling in RA, and discuss current applications and future directions for targeting the cGAS-STING signaling in RA treatments.

Inherited C-terminal TREX1 variants disrupt homology-directed repair to cause senescence and DNA damage phenotypes in Drosophila, mice, and humans

Age-related microangiopathy, also known as small vessel disease (SVD), causes damage to the brain, retina, liver, and kidney. Based on the DNA damage theory of aging, we reasoned that genomic instability may underlie an SVD caused by dominant C-terminal variants in TREX1, the most abundant 3'-5' DNA exonuclease in mammals. C-terminal TREX1 variants cause an adult-onset SVD known as retinal vasculopathy with cerebral leukoencephalopathy (RVCL or RVCL-S). In RVCL, an aberrant, C-terminally truncated TREX1 mislocalizes to the nucleus due to deletion of its ER-anchoring domain. Since RVCL pathology mimics that of radiation injury, we reasoned that nuclear TREX1 would cause DNA damage. Here, we show that RVCL-associated TREX1 variants trigger DNA damage in humans, mice, and Drosophila, and that cells expressing RVCL mutant TREX1 are more vulnerable to DNA damage induced by chemotherapy and cytokines that up-regulate TREX1, leading to depletion of TREX1-high cells in RVCL mice. RVCL-associated TREX1 mutants inhibit homology-directed repair (HDR), causing DNA deletions and vulnerablility to PARP inhibitors. In women with RVCL, we observe early-onset breast cancer, similar to patients with BRCA1/2 variants. Our results provide a mechanistic basis linking aberrant TREX1 activity to the DNA damage theory of aging, premature senescence, and microvascular disease.

Inflammatory macrophage reprogramming strategy of fucoidan microneedles-mediated ROS-responsive polymers for rheumatoid arthritis

During the pathogenesis of rheumatoid arthritis, inflammatory cells usually infiltrate synovial tissues, notably, M1-type macrophages, whose redox imbalance leads to the degradation of joint structures and deterioration of function. Natural active products play a vital role in immune modulation and antioxidants. In this study, we constructed a ROS-responsive nanoparticle called FTL@SIN, which consists of fucoidan (Fuc) and luteolin (Lut) connected by a ROS-responsive bond, Thioketal (TK), and encapsulated with an anti-rheumatic drug, Sinomenine (SIN), for synergistic anti-inflammatory effects. The FTL@SIN is then dispersed in high molecular weight Fuc-fabricated dissolvable microneedles (FTL@SIN MNs) for local administration. Therapy of FTL@SIN MNs afforded a significant decrease in macrophage inflammation while decreasing key pro-inflammatory cytokines and repolarizing M1 type to M2 type, thereby ameliorating synovial inflammation, and promoting cartilage repair. Additionally, our investigations have revealed that Fucoidan (Fuc) demonstrates synergistic effects, exhibiting superior mechanical strength and enhanced physical stability when compared to microneedles formulated solely with hyaluronic acid. This study combines nanomedicine with traditional Chinese medicine, a novel drug delivery strategy that presents a promising avenue for therapeutic intervention in rheumatoid arthritis.

Inactivation of Myostatin Delays Senescence via TREX1-SASP in Bovine Skeletal Muscle Cells

The myostatin (MSTN) gene also regulates the developmental balance of skeletal muscle after birth, and has long been linked to age-related muscle wasting. Many rodent studies have shown a correlation between MSTN and age-related diseases. It is unclear how MSTN and age-associated muscle loss in other animals are related. In this study, we utilized MSTN gene-edited bovine skeletal muscle cells to investigate the mechanisms relating to MSTN and muscle cell senescence. The expression of MSTN was higher in older individuals than in younger individuals. We obtained consecutively passaged senescent cells and performed senescence index assays and transcriptome sequencing. We found that senescence hallmarks and the senescence-associated secretory phenotype (SASP) were decreased in long-term-cultured myostatin inactivated (MT-KO) bovine skeletal muscle cells (bSMCs). Using cell signaling profiling, MSTN was shown to regulate the SASP, predominantly through the cycle GMP-AMP synthase-stimulator of antiviral genes (cGAS-STING) pathway. An in-depth investigation by chromatin immunoprecipitation (ChIP) analysis revealed that MSTN influenced three prime repair exonuclease 1 (TREX1) expression through the SMAD2/3 complex. The downregulation of MSTN contributed to the activation of the MSTN-SMAD2/3-TREX1 signaling axis, influencing the secretion of SASP, and consequently delaying the senescence of bSMCs. This study provided valuable new insight into the role of MSTN in cell senescence in large animals.

Observational study on the potential mechanism of Sanao decoction in the treatment of asthma based on network pharmacology and molecular docking

Bronchial asthma (BA) is a chronic respiratory disease closely related to immune system dysregulation. Traditional Chinese medicine has long adopted the strategy of Sanao decoction in the treatment of bronchial asthma. However, due to the multi-target and multi-pathway characteristics of Chinese herbal medicine, we are still unclear about the specific mechanism of Sanao decoction in treating bronchial asthma. To investigate the mechanism of action of Sanao decoction in the treatment of BA using a network pharmacology approach and preliminary validation by molecular docking technology. Traditional Chinese medicine systems pharmacology database and analysis platform and UniProt databases were used to search the active ingredients and targets of Sanao decoction, and BA-related targets were screened according to GeneCards and online Mendelian inheritance in man database databases. The intersection targets were imported into the STRING database to construct a protein-protein interaction network, and Cytoscape 3.9.1 software was used to screen out hub genes. This study also constructed a "drug-ingredient-target" visual network diagram. Gene Ontology and Kyoto Encyclopedia of Genomes enrichment analysis was performed on targets in the protein-protein interaction network using the ClusterProfiler package in R, with a P value < .05. Autodock software was used for molecular docking to complete the preliminary verification of core components and targets. A total of 73 active compounds and 308 targets of Sanao decoction, including 1640 BA-related disease targets, were retrieved from mainstream databases. Gene Ontology analysis and Kyoto encyclopedia of genes and genomes enrichment analysis suggested that Sanao decoction plays a role in the treatment of BA through signaling pathways such as PI3K-Akt, MAPK, and IL-17 signaling pathway. The 9 core goals represent the main elements related to Sanao decoction in the treatment of BA. Subsequently, the molecular docking results showed that most of the active compounds of Sanao decoction have strong binding efficiency with the hub gene. Sanao decoction has a key impact on BA through multiple channels. In summary, this intricate network reflects the potential of Sanao decoction in treating BA, a multifactorial disease. In addition, this study laid the foundation for further in vivo and in vitro experimental research and expanded the clinical application of Sanao decoction.