Hypoxia, mitochondrial dysfunction and synovial invasiveness in rheumatoid arthritis

Bioactive phosphorus dendrimers deliver protein/drug to tackle osteoarthritis via cooperative macrophage reprogramming

Reprogramming imbalanced synovial macrophages and shaping an immune microenvironment conducive to bone and cartilage growth is crucial for efficient tackling of osteoarthritis (OA). Herein, we present a co-delivery nanosystem based on generation 2 (G2) hydroxyl-terminated bioactive phosphorus dendrimers (G2-OH24) that were loaded with both catalase (CAT) and quercetin (Que). The created G2-OH24/CAT@Que complexes exhibit a uniformly distributed spherical morphology with a size of 138.8 nm, possess robust stability, and induce macrophage reprogramming toward anti-inflammatory M2 phenotype polarization and antioxidation through cooperative CAT-catalyzed oxygen generation, Que-mediated mitochondrial homeostasis restoration, and inherent immunomodulatory activity of dendrimer. Such macrophage reprogramming leads to chondrocyte apoptosis inhibition and osteogenic differentiation of bone mesenchymal stem cells. Administration of G2-OH24/CAT@Que to an OA mouse model results in attenuation of pathological features such as cartilage degeneration, bone erosion, and synovitis through oxidative stress alleviation and inflammatory factor downregulation in inflamed joints. Excitingly, the G2-OH24/CAT@Que also polarized macrophages in adherent effusion monocytes (AEMs) extracted from joint cavity effusions of OA patients to M2 phenotype and downregulated reactive oxygen species levels in AEMs. This study suggests a promising nanomedicine formulation of phosphorus dendrimer-based co-delivery system to effectively tackle OA through the benefits of full-active ingredients of dendrimer, drug, and protein.

Polymer-modified DNA hydrogels for living mitochondria and nanozyme delivery in the treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that leads to joint deformities and functional impairments. Traditional treatment approaches, such as nonsteroidal anti-inflammatory drugs, disease-modifying antirheumatic drugs, and molecular targeted therapies, often fail to simultaneously achieve efficient inflammation relief and cartilage tissue repair. DNA hydrogels, derived from nucleic acid nanotechnology, have demonstrated potential in RA therapy due to their programmability, high biocompatibility, and tunable degradation properties. However, their application is still hindered by challenges including high synthesis costs, immunogenicity risks, and uncontrolled degradation rates. To address these limitations, this study proposes a dual-action strategy involving a polymer-modified DNA hydrogel co-delivering nanozymes and living mitochondria to overcome the constraints of traditional therapies and comprehensively optimize RA treatment outcomes. The incorporation of functionalized polymers significantly reduces synthesis costs and immunogenicity while fine-tuning the degradation rate of the hydrogel, enabling sustained support during bone and cartilage repair. The hydrogel is loaded with Prussian blue nanozymes to scavenge excessive reactive oxygen species (ROS) within the RA microenvironment, alleviating inflammation, and facilitates intracellular delivery of living mitochondria to inhibit ROS production at its source, promoting tissue repair. By integrating endogenous ROS reduction with exogenous ROS clearance, this strategy markedly enhances therapeutic efficacy, offering a novel approach for precise RA treatment and advancing the clinical translation of biomaterials.

Study on the effect of deer bone in improving rheumatoid arthritis based on the "drug-target-pathway" association network

ETHNOPHARMACOLOGICAL RELEVANCE

Deer bone is rich in proteins, free amino acids, chondroitin, organic calcium, phosphorus ions, and other active components. Deer bone had been used widely in antiquity and were first compiled in renowned ancient masterpiece 'Mingyi Bielu ()' written by Hongjing Tao. The deer bone is recorded as non-toxic and has the effects of replenishing bones, strengthening sinews, expelling wind-dampness from the body, promoting muscle growth, and healing wounds. Modern pharmacological research suggests that deer bone can help promote bone density and enhance bone strength, making it potentially valuable for the prevention and treatment of diseases such as rheumatoid arthritis and osteoporosis. However, current studies on the component analysis and pharmacological effects of deer bone against rheumatoid arthritis (RA) are incomplete, which to some extent hinders the development and clinical application of deer bone drugs.

AIM OF THE STUDY

The components of deer bone were elucidated by label-free proteomics, and the drug-target-pathway association network was established by network pharmacology. The in vitro validation of the pathway provides a theoretical basis for deer bone as a potential therapeutic drug for rheumatoid arthritis, and also lays a solid foundation for the subsequent clinical application of the in vitro experiments established through serum pharmacology.

MATERIALS AND METHODS

We performed extraction of deer bone using traditional water extraction methods and employed label-free proteomics technology to identify and conduct bioinformatics analysis on the proteins and peptides in the deer bone hot water extract (DBHE). These components were considered potential drug targets, and we constructed a "drug-target-pathway" association network. Analysis revealed that the HIF-1 signaling pathway may be pivotal in DBWE's effect on RA. Hypoxia influences the occurrence and development of ferroptosis through various mechanisms. Therefore, we hypothesized that DBWE might induce ferroptosis, promoting apoptosis in RA-FLS under hypoxic conditions, thereby alleviating RA. Therefore, we performed flow cytometry, ELISA, immunofluorescence, RT-qPCR, and western blotting based on molecular docking. Considering the overall effect of drug metabolism post-ingestion, we used serum pharmacology to prepare serum for cellular administration.

RESULTS

It showed that DBWE reduces inflammation and synovial proliferation by inhibiting HO-1, increasing ROS production, upregulating ACSL4 expression and inducing RA-FLS apoptosis in hypoxic conditions. This study reveals the potential mechanism by which DBWE modulates ferroptosis to attenuate synovial proliferation in a hypoxic microenvironment and improve RA.

CONCLUSION

These findings not only provide a theoretical basis for deer bone as a potential therapeutic agent for RA, but also lay a solid foundation for subsequent clinical application through in vitro experiments established by serum pharmacology.

Deficiency of FUN14 domain-containing 1 enhances the migration and invasion of fibroblast-like synoviocytes in rheumatoid arthritis through mitochondrial dysregulation

BACKGROUND

Fibroblast-like synoviocytes (FLS) display aggressive phenotypes contributing to synovitis and joint destruction in rheumatoid arthritis (RA). Disrupted mitochondrial homeostasis has been proposed to aggravate the RA pathogenesis, however, the underlying mechanism remains to be elucidated. This study aimed to elucidate the role of mitophagy receptor FUN14 domain-containing 1 (FUNDC1) on RA-FLS migration and invasion.

METHODS

We analyzed the correlation of synovial FUNDC1 expression with joint destruction and disease activity in RA patients. Single cell sequencing data analysis combined with immunofluorescence indicated the specific expression and localization of FUNDC1 in synovial tissue and RA-FLS. The roles of FUNDC1 in the migration, invasion, and cytokine secretion of RA-FLS were examined by patient-derived primary culture as well as SCID mouse models. We investigated the effects and mechanism of FUNDC1 on mitophagy and mitochondrial quality control network in primary RA-FLS.

RESULTS

We found that the FUNDC1 was mainly expressed in FLS and exhibited a decreased level in RA synovium, which was correlated with severe joint destruction. Deficiency of FUNDC1 enhanced migration, invasion as well as secretion of matrix metalloproteinases in RA-FLS. On the contrary, overexpression of FUNDC1 in RA-FLS with low FUNDC1 inhibited the migration, invasion and secretion capacity of RA-FLS. Mechanistically, repressed FUNDC1 level in RA-FLS impaired mitophagy, imbalanced mitochondrial quality control, and increased mitochondrial reactive oxygen species (mtROS) production, leading to the overactivation of the MAPK pathway. Treatment with mtROS scavenger mtTEMPO can reverse this process and diminish the invasiveness of RA-FLS.

CONCLUSIONS

Deficiency of FUNDC1 dysregulates mitochondrial quality-control system and induces aggressive phenotype of RA-FLS, resulting in joint destruction during RA progression.

Metabolic reprogramming of macrophages by a nano-sized opsonization strategy to restore M1/M2 balance for osteoarthritis therapy

Osteoarthritis is a chronic and progressive joint disease accompanied by cartilage degeneration and synovial inflammation. It is associated with an imbalance of synovial macrophage M1/M2 ratio tilting more towards the pro-inflammatory M1 than the anti-inflammatory M2. The M1-macrophages rely on aerobic glycolysis for energy whereas the M2-macrophages derive energy from oxidative phosphorylation. Therefore, inhibiting aerobic glycolysis to induce metabolic reprogramming of macrophages and consequently promote the shift from M1 type to M2 type is a therapeutic strategy for osteoarthritis. Here we developed a macrophage-targeting strategy based on opsonization, using nanoparticles self-assembled to incorporate Chrysin (an anti-inflammatory flavonoid) and V-9302 (an inhibitor of glutamine uptake), and the outer layer modified by immunoglobulin IgG by electrostatic adsorption into IgG/Fe-CV NPs. In vitro studies showed that IgG/Fe-CV NPs effectively target M1 macrophages and inhibit HIF-1α and GLUT-1 essential for aerobic glycolysis and promote polarization from M1 to M2-type macrophages. In vivo, IgG/Fe-CV NPs inhibit inflammation and protect against cartilage damage. The metabolic reprogramming strategy with IgG/Fe-CV NPs to shift macrophage polarization from inflammatory to anti-inflammatory phenotype by inhibiting aerobic glycolysis and glutamine delivery may open up new avenues to treat osteoarthritis.

Mitochondrial calcium uniporter regulates human fibroblast-like synoviocytes invasion via altering mitochondrial dynamics and dictates rheumatoid arthritis pathogenesis

Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disease that currently has no cure. Fibroblast-like synoviocytes (FLS), present in the RA synovium, play a pivotal role in RA pathogenesis. Notably, FLS in the RA patients (RA-FLS) exhibit characteristics similar to cancer cells, like enhanced migration, invasiveness, uncontrolled proliferation, resistance to apoptosis, and metabolic reprogramming. RA-FLS invasiveness is linked to radiographic joint damage in the patients, whereas inhibiting the FLS migration mitigates disease pathology. However, the molecular mechanisms underlying the migration and invasion capabilities of RA-FLS are not entirely understood. In this work, we have explored the function of mitochondrial calcium uniporter (MCU) and calcium signaling in FLS invasion. Our findings demonstrate a positive correlation between MCU expression and RA disease score. Interestingly, mitochondrial size was reduced, and peripheral localization was more pronounced in the RA-FLS when compared to the control FLS. Mitochondrial calcium import inhibition in the FLS by specific MCU inhibitor, Ruthenium-360 restored these altered mitochondrial dynamics and reduced the invasive phenotype. Through unbiased transcriptome analysis, we identified that MCU-mediated calcium signaling in RA-FLS leads to the enriched actin cytoskeleton and focal adhesion pathways responsible for the invasion phenotype, which can be effectively suppressed by inhibiting MCU. Additionally, we found that mitochondrial transport facilitator Miro1 binds to MCU in a calcium-dependent manner and regulates MCU-mediated mitochondrial dynamics and RA-FLS invasion. Experiments utilizing mice xenograft model demonstrated that MCU silencing diminishes the migration of RA-FLS toward the sites of inflammation in the immunocompromised SCID mice. Altogether, our findings highlight MCU as a promising therapeutic target to inhibit RA-FLS migration and RA progression.

Innovative nanocarriers in arthritis therapy: the role of herbal cubosomes

BACKGROUND

Both osteoarthritis (OA) and rheumatoid arthritis (RA) are long-lasting inflammatory disorders that impact the joints. While conventional treatments like NSAIDs and DMARDs are effective, they often have adverse side effects.

OBJECTIVE

The aim of this review is to explore the possibilities of using herbal treatments in treating the symptoms of arthritis, their stability and bioavailability. Traditional therapies often lead to adverse side effects, prompting a search for safer alternatives, particularly in herbal medicines. This review explores the innovative use of herbal cubosomes as advanced nanocarriers for arthritis therapy. Cubosomes, a type of self-assembled lipid nanoparticle, exhibit unique structural characteristics that enhance the delivery and bioavailability of encapsulated herbal compounds.

METHOD

Access was gained to PubMed, Scopus database, Google Scholar and Web of Science for the literature search. The results were later screened according to the titles, abstracts, and availability of full texts.

RESULTS

The expository evaluation of the literature revealed that Key herbal components, such as Withania somnifera (Ashwagandha), Curcuma longa (Turmeric) and Boswellia serrata (Frankincense) are emphasized for their anti-inflammatory characteristics and possible advantages in managing arthritis. The herbal cubosomes enhance drug absorption, retention, and release kinetics in arthritic conditions. The difficulties in delivering and maintaining herbal substances are also discussed, with a focus on how nanotechnology can help get over these obstacles.

CONCLUSION

Overall, the integration of herbal cubosomes in arthritis therapy presents a promising approach that could result in safer and more efficient treatment alternatives, warranting further research and clinical exploration.

Layered Double Hydroxide Reshapes the Immune Microenvironment of Rheumatoid Arthritis through Small Mothers against Decapentaplegic 5

Persistent synovitis is a pivotal pathological feature of rheumatoid arthritis (RA). However, the current rheumatoid drugs are accompanied by severe side effects and have limited anti-inflammatory capabilities. In this work, we designed a bioactive material-folic acid modified layered double hydroxides (FA-LDH), aiming at targeting M1 macrophages and modulating macrophage repolarization. The in vitro experiment showed that FA-LDH mitigated the release of proinflammatory cytokines and promoted the expression of M2 macrophage markers. In terms of the action mechanism, FA-LDH modulated the nucleocytoplasmic transport of the small mothers against decapentaplegic 5 (Smad5) protein by adjusting the pH within the immune microenvironment. Subsequently, relying on the interaction between phospho-Smad5 (pSmad5) and p65, the nuclear factor kappa B signaling pathway was down-regulated through inhibiting nuclear transport of p65. Additionally, FA-LDH exhibited excellent targeting capability toward M1 macrophages and strong accumulation capacity in inflamed joints. In vivo experiment showed that FA-LDH could relieve swelling of limbs, reduce the infiltration of inflammatory cells, and protect joint cartilage and subchondral bone structure in collagen-induced arthritis mice. In summary, this work introduces a strategy for utilizing bioactive FA-LDH in the treatment of RA, highlighting the potential of FA-LDH to alleviate inflammation and reshape the immune microenvironment through the pSmad5/p65 axis.

HIF-1α mediates mitochondrial damage by down-regulating ALKBH7 expression to promote the aberrant activation of FLS in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovial inflammation and progressive joint destruction. Existing evidence indicates that hypoxia potentially contributes to the pathology of RA, though the specific mechanism remains unidentified. In this study, we explored the molecular mechanism through which the hypoxia-inducible factor (HIF-1α) contributed to the pathological process of RA. Our preliminary results suggested that hypoxia stimulates the activation of fibroblast-like synoviocytes (FLS) by inducing mitochondrial damage to activate cGAS-STING signaling, which can be effectively inhibited by silencing HIF-1α. In line with this, HIF-1α deficiency significantly alleviated the symptoms of collagen-induced arthritis (CIA) mice. RNA-Seq and CUT-Tag analysis revealed that HIF-1α down-regulated the expression of AlkB homologue 7 (ALKBH7) by acting on the ALKBH7 promoter site on chromosome 19 6372400-6372578. Using dual luciferase reporter analysis, we identified that ACCGTGGC as the motif to which HIF-1α bound directly. Subsequently, we demonstrated that knockdown of ALKBH7 induces mitochondrial damage and activates cGAS-STING signaling by downregulating the expression of UQCRC2. Conversely, overexpression of ALKBH7 could resist hypoxia-induced mitochondrial damage and FLS activation. In conclusion, HIF-1α triggers mitochondrial damage by downregulating the expression of ALKBH7 thereby promoting FLS activation, which may be the molecular mechanism by which hypoxia is involved in the pathological process of RA. Hypoxia promotes the activation of FLS through the induction of mitochondrial damage, which subsequently activates cGAS-STING signaling. Mechanistically, HIF-1α triggers mitochondrial damage by downregulating the expression of ALKBH7 in a target manner. Furthermore, the deletion of ALKBH7 leads to mitochondrial damage under hypoxic conditions, primarily through the downregulation of UQCRC2, as opposed to other complexes.

Inhibition of Aberrant Activated Fibroblast-Like Synoviocytes in Rheumatoid Arthritis by Leishmania Peptide via the Regulation of Fatty Acid Synthesis Metabolism

The Leishmania homolog of receptors for activated C kinase (LACK) protein is derived from Leishmania parasites L. major. The polypeptide LACK156-173 has been shown to confer protection against murine autoimmune arthritis. Fibroblast-like synoviocytes (FLSs) play a pivotal role in the synovial invasion and joint destruction observed in rheumatoid arthritis (RA). The study reveals that LACK156-173 can inhibit the aggressive phenotype of RA-FLSs by restoring dysregulated fatty acid synthesis metabolism. In RA-FLSs, overexpression of fatty acid synthase (FASN) leads to excessive fatty acid accumulation, which in turn promotes mitochondrial fragmentation by enhancing phosphorylation at the ser616 site of dynamin 1-like protein (DRP1). This process increases reactive oxygen species (ROS) production and activates the PI3K/mTOR/NF-κB pathway, thereby facilitating the transition of RA-FLSs to an aggressive inflammatory and bone-damaging phenotype. LACK156-173 is internalized into the cytoplasm via CAPN2-mediated endocytosis, where it directly binds to FASN and inhibits its activity. The findings suggest that targeting the restoration of fatty acid metabolism could potentially alleviate synovial invasion and joint damage in RA. LACK156-173 may therefore hold therapeutic promise for RA patients.

Peptide-Oligonucleotide Nanohybrids Designed for Precise Gene Therapy of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by excessive inflammation, pathological bone resorption, and systemic osteoporosis. It lacks effective treatment due to the complex pathogenesis. Gene therapy, especially targeted oligonucleotide (ON) delivery therapy, offers a new prospect for the precise treatment of RA. Nevertheless, the clinical application of ON delivery therapy still faces various challenges such as the rapid enzymolysis by RNAse, the lack of tissue targeting ability, difficulty in cell membrane penetration, and the incapability of endolysosomal escape. To address these issues, a novel kind of engineered peptide and oligonucleotide (PON) nanohybrids are designed and fabricated, which provide various advantages including good biosafety, inflammatory region-targeted delivery, cell membrane penetration, reactive oxygen species (ROS) scavenging, and endolysosomal escape. The PON nanohybrids produce promising effects in suppressing inflammatory responses and osteoclastogenesis of macrophages via multiple signaling pathways. In vivo administration of PON nanohybrids not only ameliorates local joint bone destruction and systemic osteoporosis in the pathological state, but also demonstrates good prophylactic effects against the rapid progression of RA disease. In conclusion, the study presents a promising strategy for precise RA treatment and broadens the biomedical applications of gene therapy based on delivery system.

Photodriven PtPdCo-TiO2 heterostructure modified with hyaluronic acid and folic acid enhances antioxidative stress through efficient hydrogen/oxygen delivery and thermal effects in rheumatoid arthritis therapy

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic synovitis and progressive joint damage, primarily caused by oxidative injury from reactive oxygen species (ROS) and hypoxia in immune cells. Hydrogen (H2) has demonstrated potential in scavenging excess ROS and correcting redox imbalances, while oxygen supplementation can alleviate hypoxia, promoting inflammatory remission. This study introduces a novel FA-HA-PtPdCo-TiO2 (F-HPPCT) nano-system for targeted RA therapy. Comprising TiO2 quantum dots on PtPdCo polyhedra, decorated with folate-hyaluronic acid (FA-HA), F-HPPCT selectively targets inflammatory cells. Its metal-semiconductor heterostructure forms Schottky junctions that enhance electron transfer, enabling efficient hydrogen evolution and a photothermal effect under near-infrared light. Additionally, F-HPPCT mimics catalase activity, decomposing overexpressed H2O2 to relieve hypoxia and oxidative stress. The system synergistically scavenges ROS and replenishes oxygen, effectively reducing inflammation and oxidative damage. Both in vitro and in vivo experiments in arthritis models confirmed its efficacy, highlighting F-HPPCT's potential as a groundbreaking nanocatalyst for gas therapy in RA treatment.

Adipose-derived stem cells attenuate rheumatoid arthritis by restoring CX3CR1+ synovial lining macrophage barrier

BACKGROUND

Rheumatoid arthritis (RA) is a chronic autoimmune disease and the integrity of CX3CR1+ synovial macrophage barrier significantly impacts its progression. However, the mechanisms driving the dynamic changes of this macrophage barrier remain unclear. Traditional drug therapies for RA have substantial limitations. Mesenchymal stem cells (MSCs)-based cell therapy, especially adipose-derived stem cells (ADSCs), hold therapeutic promise. Nevertheless, the underlying therapeutic mechanism of ADSCs, especially their interactions with CX3CR1+ macrophages, require further investigation.

METHODS

To explore the interaction between ADSCs and CX3CR1+ synovial macrophages during barrier reconstruction, underlying the therapeutic mechanism of ADSCs and the mechanisms on the dynamic changes of the macrophage barrier, scRNA-seq analysis was conducted 4 days after ADSCs injection in serum transfer-induced arthritis model mice. The roles of mitochondria transfer and ADSCs transplantation were also explored. Bulk RNA-seq analysis was performed after the co-culture of ADSCs and CX3CR1+ synovial macrophages. To study the in vivo fate of ADSCs, bulk RNA-seq was performed on ADSCs retrieved at 0, 2, 4, and 7 days post-injection.

RESULTS

Intra-articular injection of ADSCs effectively attenuated the pathological progression of mice with serum transfer-induced arthritis. ADSCs gradually adhered to CX3CR1+ macrophages, facilitating the restore of the macrophage barrier, while the absence of this barrier greatly weakened the therapeutic effect of ADSCs. scRNA-seq analysis revealed an Atf3high Ccl3high subset of CX3CR1+ macrophages with impaired oxidative phosphorylation that increased during RA progression. ADSCs-mediated reduction of this subset appeared to be linked to mitochondrial transfer, and transplantation of isolated ADSCs-derived mitochondria also proved effective in treating RA. Both bulk RNA-seq and scRNA-seq analyses revealed multiple interaction mechanisms between ADSCs and CX3CR1+ macrophages, including Cd74/Mif axis and GAS6/MERTK axis, which contribute to barrier restoration and therapeutic effects. Furthermore, bulk RNA-seq analysis showed that ADSCs primarily contribute to tissue repair and immune regulation subsequently.

CONCLUSIONS

Our results suggest that ADSCs ameliorated the energy metabolism signature of CX3CR1+ lining macrophages and may promote barrier restoration through mitochondria transfer. In addition, we elucidated the fate of ADSCs and the therapeutic potential of mitochondria in RA treatment.

Biomimetic Nanoparticles Inhibit the HIF-1α/iNOS/NLRP3 Pathway to Alleviate Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease distinguished by inflammatory synovitis. Chrysin can alleviate the inflammatory response and inhibit the progression of RA. However, unfavorable physicochemical properties and nonselective biodistribution of chrysin make it difficult to achieve good therapeutic efficacy. To address these challenges, we developed a biomimetic nanocarrier to enhance the targeted delivery of chrysin to synoviocytes, a key cellular component in RA pathology. Our nanodrug, FMPlipo@C, was engineered by integrating fibroblast-like synoviocyte (FLS) membrane proteins into chrysin-loaded liposomes. This innovative approach harnesses homologous targeting mediated by FLS membrane proteins to direct liposomes to inflamed joints, facilitating cargo release within synoviocytes. We showed that FMPlipo@C reduces inflammation in collagen-induced rheumatoid arthritis (CIA) model mice by inhibiting the HIF-1α/iNOS/NLRP3 pathway, protecting cartilage, and preventing bone erosion, thus reducing swelling and stiffness. This study offers valuable insights into the development of novel therapeutic strategies for the treatment of RA.

Macrophage corpses for immunoregulation and targeted drug delivery in treatment of collagen-induced arthritis mice

The role of pro-inflammatory macrophages (M1) in rheumatoid arthritis (RA) is significant, as they produce excessive cytokines. Targeting efferocytosis is a potential manner to repolarize M1 macrophages into pro-resolving M2 phenotype, which restores immune homeostasis by releasing anti-inflammatory mediators. In this study, liquid nitrogen-treated dead macrophages (DM) are employed to act as a dead cell-derived active targeted drug carrier for shikonin (SHK) and induce efferocytosis in M1 macrophages with the enhancement of SHK as an AMP-activated protein kinase (AMPK)-activator. The synergistic activation of AMPK leads to uncoupled protein 2 (UCP2) upregulation and reprograms M1 macrophages into M2 phenotypes by promoting oxidative phosphorylation. In the mouse model of collagen-induced arthritis, the intravenous administration of DM/SHK leads to a consistent transformation of M1 macrophages into the M2 phenotype within the infiltrative synovium. This transformation of macrophages results in the restoration of immune homeostasis in the synovium through an increase in the production of pro-resolving mediators. Additionally, it inhibits synovial proliferation and infiltration and provides protection against erosion of cartilage and bone. In summary, LNT-based DM serves as an active targeting drug carrier to M1 macrophages and also acts synergistically with SHK to target immunometabolism.

Regulation of pathologic fibroblast functions in digestive diseases: a role for hypoxia?

The recent uncovering of fibroblast heterogeneity has given great insight into the versatility of the stroma. Among other cellular processes, fibroblasts are now thought to contribute to the coordination of immune responses in a range of chronic inflammatory diseases and cancer. Although the pathologic roles of myofibroblasts, inflammatory fibroblasts, and cancer-associated fibroblasts in disease are reasonably well understood, the mechanisms behind their activation remain to be uncovered. In the gastrointestinal (GI) tract, several interleukins and tumor necrosis factor superfamily members have been identified as possible mediators driving the acquisition of inflammatory and fibrotic properties in fibroblasts. In addition to cytokines, other microenvironmental factors such as nutrient and oxygen availability are likely contributors to this process. In this respect, the phenomenon of low cellular oxygen levels known as hypoxia is common in a plethora of GI diseases. Indeed, the cross talk between hypoxia and inflammation is well-documented, with an abundance of studies suggesting that oxygen-sensing enzymes may have regulatory effects on inflammatory signaling pathways such as NF-κB. However, the impact that this has in GI fibroblasts in the context of chronic diseases has not been fully uncovered. Here we discuss the role of fibroblasts in GI diseases, the mediators that have emerged as regulators of their functions and the potential impact of hypoxia in this process, highlighting areas that require further investigation.

The protective role of kakkalide in sepsis-induced intestinal barrier dysfunction via inhibition of NF-κB pathway activation

Sepsis, a systemic inflammatory response often triggered by infection, can lead to multi-organ failure, with the intestine being one of the most vulnerable organs. The nuclear factor kappa-B (NF-κB) pathway plays a crucial role in immune responses, inflammation, and cell survival, making it central to sepsis-induced intestinal damage. Kakkalide (KA), a bioactive compound known for its anti-inflammatory, cardiovascular, neuroprotective, and anti-diabetic properties, has potential therapeutic effects. However, its impact on sepsis-induced intestinal injury remains unclear. In this study, murine sepsis models were used both in vivo and in vitro to evaluate the protective effects of KA on intestinal histopathology, apoptosis, and inflammation. Results showed that KA significantly reduced intestinal damage and apoptosis, as evidenced by hematoxylin-eosin and TUNEL staining. KA also improved intestinal barrier integrity, as indicated by reduced diamine oxidase activity, d-lactic acid content, and fluorescein isothiocyanate intensity, along with increased expression of zonula occludens-1. Furthermore, KA alleviates inflammation by reducing the levels of tumor necrosis factor-α, interleukin-1β, prostaglandin E2, inducible nitric oxide synthase, and cyclooxygenase-2. Immunofluorescence and Western blot analysis revealed that KA inhibited the sepsis-induced phosphorylation of inhibitor-kappaBα and RelA (P65) and prevented P65's translocation to the nucleus. These findings were confirmed in lipopolysaccharide-induced Caco-2 cells, suggesting that KA protected the intestinal barrier during sepsis by suppressing the NF-κB pathway.

Multimorbidity patterns and influencing factors in older Chinese adults: a national population-based cross-sectional survey

Background

This study aims to develop specific multimorbidity relationships among the elderly and to explore the association of multidimensional factors with these relationships, thereby facilitating the formulation of personalised strategies for multimorbidity management.

Methods

Cluster analysis identified chronic conditions that tend to cluster together, and then association rule mining was used to investigate relationships within these identified clusters more closely. Stepwise logistic regression analysis was conducted to explore the relationship between influencing factors and different health statuses in older adults. The results of this study were presented by network graph visualisation.

Results

A total of 15 045 individuals were included in this study. The average age was 73.0 ± 6.8 years. The number of patients with multimorbidity was 7426 (49.4%). The most common binary disease combination was hypertension and depression. The four major multimorbidity clusters identified were the tumour-digestive disease cluster, the metabolic-circulatory disease cluster, the metal-psychological disease cluster, and the age-related degenerative disease cluster. Cluster analysis by sex and region revealed similar numbers and types of conditions in each cluster, with some variations. Gender and number of medications had a consistent effect across all disease clusters, while aging, body mass index (BMI), waist-to-hip ratio (WHR), cognitive impairment, plant-based foods, animal-based foods, highly processed foods and marital status had varying effects across different disease clusters.

Conclusions

Multimorbidity is highly prevalent in the older population. The impact of lifestyle varies between different clusters of multimorbidity, and there is a need to implement different strategies according to different clusters of multimorbidity rather than an integrated approach to multimorbidity management.

Application of cell therapy in rheumatoid Arthritis: Focusing on the immunomodulatory strategies of Mesenchymal stem cells

Rheumatoid arthritis (RA) is a common chronic autoimmune disease that primarily affects the joints, leading to synovial inflammation and hyperplasia, which subsequently causes joint pain, swelling, and damage. The microenvironment of RA is characterized by hypoxia, high reactive oxygen species (ROS), low pH, and levels of high inflammatory factors. Traditional treatments only partially alleviate symptoms and often cause various adverse reactions with long-term use. Therefore, there is an urgent need for safer and more effective treatments. In recent years, mesenchymal stem cells (MSCs) have shown significant potential in treating RA due to their diverse immunomodulatory mechanisms. MSCs paracrine a variety of soluble factors to improve the inflammatory microenvironment in RA patients by inhibiting T cell proliferation or inducing T cell differentiation to regulatory T cells (Tregs), inhibiting B cell proliferation and differentiation and immunoglobulin production, prompting macrophage polarization toward an anti-inflammatory phenotype, and inhibiting neutrophil recruitment and preventing the maturation of dendritic cells (DCs). This review summarizes the immunomodulatory effects of MSCs in RA and their application in animal models and clinical trials. Although the immunomodulatory mechanisms of MSCs are not yet fully elucidated, their significant potential in RA treatment has been widely recognized. Future research should further explore the immunomodulatory mechanisms of MSCs and optimize their functions in different pathological microenvironments to develop more effective and safer therapeutic strategies.

Dual-State Emissive Mitochondrial Viscosity Probe for Long-Term Imaging of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a destructive autoimmune disease that seriously affects human health. Due to the lack of a cure for RA, a good prognosis largely depends on early diagnosis and effective treatment monitoring of RA. Therefore, the development of fluorescent probes capable of real-time detection of RA is of great significance. Dual-state emission (DSE) molecules can emit light in both dilute solution and solid state, making them ideal fluorophores for constructing fluorescent probes. However, there are currently no reports of DSE molecule-based fluorescent probes for RA imaging. Herein, we report a fluorescent probe MQP-Boc based on a novel DSE molecule for effective RA imaging. MQP-Boc selectively responds to viscosity with sensitive fluorescence changes at 667 nm and is mitochondria targetable. Cell imaging studies show that MQP-Boc can detect changes in mitochondrial viscosity and perform long-term imaging of mitochondria, which is significantly superior to that of the control probe MQP-Ac. Imaging studies on a mouse model of RA induced by λ-carrageenan show that MQP-Boc has excellent real-time and long-term imaging capabilities for RA. Besides, with MQP-Boc, significant increases in joint tissue viscosity were found during the RA process. All results indicate that MQP-Boc is an effective new tool for studying and diagnosing RA.

Transcription Factor Blimp-1: A Central Regulator of Oxidative Stress and Metabolic Reprogramming in Chronic Inflammatory Diseases

B-lymphocyte-induced maturation protein 1 (Blimp-1) is a transcription factor that, among other functions, modulates metabolism and helps to regulate antioxidant pathways, which is important in the context of chronic inflammatory diseases like diabetes, cardiovascular disease, and autoimmune disease. In immune cell function, Blimp-1 has a modulatory role in the orchestration of metabolic reprogramming and as a promoter of anti-inflammatory cytokines, including IL-10, responsible for modulating oxidative stress and immune homeostasis. Moreover, Blimp-1 also modulates key metabolic aspects, such as glycolysis and fatty acid oxidation, which regulate reactive oxygen species levels, as well as tissue protection. This review depicts Blimp-1 as an important regulator of antioxidant defenses and anti-inflammation and suggests that the protein could serve as a therapeutic target in chronic inflammatory and metabolic dysregulation conditions. The modulation of Blimp-1 in diseases such as diabetic coronary heart disease and atherosclerosis could alleviate oxidative stress, augment the protection of tissues, and improve disease outcomes. The therapeutic potential for the development of new treatments for these chronic conditions lies in the synergy between the regulation of Blimp-1 and antioxidant therapies, which are future directions that may be pursued. This review emphasizes Blimp-1's emerging importance as a novel regulator in the pathogenesis of inflammatory diseases, providing new opportunities for therapeutic intervention.

Functional hydrogel empowering 3D printing titanium alloys

Titanium alloys are widely used in the manufacture of orthopedic prosthesis given their excellent mechanical properties and biocompatibility. However, the primary drawbacks of traditional titanium alloy prosthesis are their much higher elastic modulus than cancellous bone and poor interfacial adhesion, which lead to poor osseointegration. 3D-printed porous titanium alloys can partly address these issues, but their bio-inertness still requires modifications to adapt to different physiological and pathological microenvironments. Hydrogels composed of three-dimensional networks of hydrophilic polymers can effectively simulate the extracellular matrix of natural bone and are capable of loading bioactive molecules such as proteins, peptides, growths factors, polysaccharides, or nucleotides for localized release within the human body, by directly participating in biological processes. Combining 3D-printed porous titanium alloys with hydrogels to construct a bioactive composite system that regulates cellular adhesion, proliferation, migration, and differentiation in the local microenvironment is of great significance for enhancing the bioactivity of the prosthesis surface. In this review, we focus on three aspects of the bioactive composite system: (Ⅰ) strategies for constructing bioactive interfaces with hydrogels, and (Ⅱ) how bioactive composite systems regulate the microenvironment under different physiological and pathological conditions to enhance the osteointegration and bone regeneration capability of prostheses. Considering the current research status in this field, innovations in orthopedic prosthesis can be achieved through material optimization, personalized customization, and the development of multifunctional composite systems. These advancements provide essential references for the clinical translation of osseointegration and bone regeneration in various physiological and pathological microenvironments.

Nanozyme-based therapeutic strategies for rheumatoid arthritis

Rheumatoid arthritis (RA) is a prevalent chronic autoimmune disease that leads to severe joint damage and disability. Conventional treatment options are limited by their efficacy and side effect profiles. Nanozymes, nanomaterials with enzyme-like activities, offer a novel therapeutic approach for RA. This review summarizes recent advances in nanozyme-based treatments, focusing on their antioxidant and immunomodulatory roles in mitigating RA. We discuss various nanozymes, including those based on cerium, iron, manganese, silver, copper, platinum, rhodium, and multi-metallic nanozymes, which mimic natural enzymes such as superoxide dismutase, catalase, and peroxidase to reduce oxidative stress. Additionally, we explore nanozyme-based combination therapies that integrate with other strategies, such as vesicles and phototherapy, to achieve synergistic effects and enhance efficacy. This review highlights the significant potential of nanozymes in improving RA treatment, offering a new perspective for future research and clinical applications.

Hypoxia Affects Mitochondrial Stress and Facilitates Tumor Metastasis of Colorectal Cancer Through Slug SUMOylation

BACKGROUND

Colorectal cancer (CRC) is a malignant tumor. Slug has been found to display a key role in diversified cancers, but its relevant regulatory mechanisms in CRC development are not fully explored.

OBJECTIVE

Hence, exploring the function and regulatory mechanisms of Slug is critical for the treatment of CRC.

METHODS

Protein expressions of Slug, N-cadherin, E-cadherin, Snail, HIF-1α, SUMO- 1, Drp1, Opa1, Mfn1/2, PGC-1α, NRF1, and TFAM were measured through western blot. To evaluate the protein expression of Slug and SUMO-1, an immunofluorescence assay was used. Cell migration ability was tested through transwell assay. The SUMOylation of Slug was examined through CO-IP assay.

RESULTS

Slug displayed higher expression and facilitated tumor metastasis in CRC. In addition, hypoxia treatment was discovered to upregulate HIF-1α, Slug, and SUMO-1 levels, as well as induce Slug SUMOylation. Slug SUMOylation markedly affected mitochondrial biosynthesis, fusion, and mitogen-related protein expression levels to trigger mitochondrial stress. Additionally, the induced mitochondrial stress by hypoxia could be rescued by Slug inhibition and TAK-981 treatment.

CONCLUSION

Our study expounded that hypoxia affects mitochondrial stress and facilitates tumor metastasis of CRC through Slug SUMOylation.

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.

Unveiling the mystery: Investigating the debate surrounding mitochondrial DNA copy number and Sjögren syndrome using Mendelian randomization analysis

Numerous studies have investigated the relationship between mitochondrial DNA (mtDNA) copy number and Sjögren syndrome (SS). However, the conclusions remain inconclusive, with conflicting findings. The genome-wide association study summary statistics for mtDNA copy number were obtained from 2 sources: a cohort of 465,809 White individuals from the Cohorts for Heart and Aging Research in Genomic Epidemiology consortium and the UK Biobank, and a dataset of 395,718 UK Biobank participants. Additionally, we obtained 2 sets of genome-wide association study summary statistics for SS through datasets from FinnGen and the UK Biobank, involving a total of 809,836 participants. Furthermore, we conducted a two-sample bidirectional Mendelian randomization analysis, primarily utilizing the inverse variance weighted method, complemented by 4 other validation methods, to explore the association between mtDNA copy number and SS. Following our comprehensive investigation, no discernible causal relationship was identified between mtDNA copy number and SS in either the training or validation cohorts (inverse variance weighted, P  > .05). Similarly, the reverse Mendelian randomization analysis yielded negative results (inverse variance weighted, P  > .05). Furthermore, all analyses indicated an absence of horizontal pleiotropy or heterogeneity. Our analysis revealed no causal relationship between mtDNA copy number and SS.

From dysfunction to healing: advances in mitochondrial therapy for Osteoarthritis

Osteoarthritis (OA) is a chronic degenerative joint condition characterised by cartilage deterioration and changes in bone morphology, resulting in pain and impaired joint mobility. Investigation into the pathophysiological mechanisms underlying OA has highlighted the significance of mitochondrial dysfunction in its progression. Mitochondria, which are cellular organelles, play a crucial role in regulating energy metabolism, generating reactive oxygen species, and facilitating essential biological processes including apoptosis. In recent years, the utilisation of exogenous drugs and MT to improve mitochondrial function in chondrocytes has shown great promise in OA treatment. Numerous studies have investigated the potential of stem cells and extracellular vesicles in mitochondrial transfer. This review aims to explore the underlying mechanisms of mitochondrial dysfunction in OA and assess the progress in utilising mitochondrial transfer as a therapeutic approach for this disease.

The shared biomarkers and immune landscape in psoriatic arthritis and rheumatoid arthritis: Findings based on bioinformatics, machine learning and single-cell analysis

OBJECTIVE

Psoriatic arthritis (PsA) and rheumatoid arthritis (RA) are the most common types of inflammatory musculoskeletal disorders that share overlapping clinical features and complications. The aim of this study was to identify shared marker genes and mechanistic similarities between PsA and RA.

METHODS

We utilized datasets from the Gene Expression Omnibus (GEO) database to identify differentially expressed genes (DEGs) and perform functional enrichment analyses. To identify the marker genes, we applied two machine learning algorithms: the least absolute shrinkage and selection operator (LASSO) and the support vector machine recursive feature elimination (SVM-RFE). Subsequently, we assessed the diagnostic capacity of the identified marker genes using the receiver operating characteristic (ROC) curve and decision curve analysis (DCA). A transcription factor (TF) network was constructed using data from JASPAR, HumanTFDB, and GTRD. We then employed CIBERSORT to analyze the abundance of immune infiltrates in PsA and RA, assessing the relationship between marker genes and immune cells. Additionally, cellular subpopulations were identified by analyzing single-cell sequencing data from RA, with T cells examined for trajectory and cellular communication using Monocle and CellChat, thereby exploring their linkage to marker genes.

RESULTS

A total of seven overlapping DEGs were identified between PsA and RA. Gene enrichment analysis revealed that these genes were associated with mitochondrial respiratory chain complex IV, Toll-like receptors, and NF-κB signaling pathways. Both machine learning algorithms identified Ribosomal Protein L22-like 1 (RPL22L1) and Lymphocyte Antigen 96 (LY96) as potential diagnostic markers for PsA and RA. These markers were validated using test sets and experimental approaches. Furthermore, GSEA analysis indicated that gap junctions may play a crucial role in the pathogenesis of both conditions. The TF network suggested a potential association between marker genes and core enrichment genes related to gap junctions. The application of CIBERSORT and single-cell RNA sequencing provided a comprehensive understanding of the role of marker genes in immune cell function. Our results indicated that RPL22L1 and LY96 are involved in T cell development and are associated with T cell communication with NK cells and monocytes. Notably, high expression of both RPL22L1 and LY96 was linked to enhanced VEGF signaling in T cells.

CONCLUSION

Our study identified RPL22L1 and LY96 as key biomarkers for PsA and RA. Further investigations demonstrated that these two marker genes are closely associated with gap junction function, T cell infiltration, differentiation, and VEGF signaling. Collectively, these findings provide new insights into the diagnosis and treatment of PsA and RA.

The role of hypoxic microenvironment in autoimmune diseases

The hypoxic microenvironment, characterized by significantly reduced oxygen levels within tissues, has emerged as a critical factor in the pathogenesis and progression of various autoimmune diseases (AIDs). Central to this process is the hypoxia-inducible factor-1 (HIF-1), which orchestrates a wide array of cellular responses under low oxygen conditions. This review delves into the multifaceted roles of the hypoxic microenvironment in modulating immune cell function, particularly highlighting its impact on immune activation, metabolic reprogramming, and angiogenesis. Specific focus is given to the mechanisms by which hypoxia contributes to the development and exacerbation of diseases such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), multiple sclerosis (MS), and dermatomyositis (DM). In these conditions, the hypoxic microenvironment not only disrupts immune tolerance but also enhances inflammatory responses and promotes tissue damage. The review also discusses emerging therapeutic strategies aimed at targeting the hypoxic pathways, including the application of HIF-1α inhibitors, mTOR inhibitors, and other modulators of the hypoxic response. By providing a comprehensive overview of the interplay between hypoxia and immune dysfunction in AIDs, this review offers new perspectives on the underlying mechanisms of these diseases and highlights potential avenues for therapeutic intervention.

Synergistic rheumatoid arthritis therapy by interrupting the detrimental feedback loop to orchestrate hypoxia M1 macrophage polarization using an enzyme-catalyzed nanoplatform

A detrimental feedback loop between hypoxia and oxidative stress consistently drives macrophage polarization toward a pro-inflammatory M1 phenotype, thus persistently aggravating rheumatoid arthritis (RA) progression. Herein, an enzyme-catalyzed nanoplatform with synergistic hypoxia-relieving and reactive oxygen species (ROS)-scavenging properties was developed using bovine serum albumin-bilirubin-platinum nanoparticles (BSA-BR-Pt NPs). Bilirubin was employed to eliminate ROS, while platinum exhibited a synergistic effect in scavenging ROS and simultaneously generated oxygen. In mice RA model, BSA-BR-Pt NPs treatment exhibited superior effects, resulting in significant improvements in joint inflammation, cartilage damage, and bone erosion, compared to methotrexate, the most widely used antirheumatic drug. Mechanistically, RNA-sequencing data and experimental results elucidated that BSA-BR-Pt NPs induced a re-polarization of hypoxic M1 macrophages to M2 macrophages via switching glycolysis to oxidative phosphorylation through the inhibition of HIF-1α pathway. Collectively, this research for the first time elaborated the underlying mechanism of enzyme-catalyzed nanoplatform in orchestrating macrophage polarization, and identified a novel therapeutic strategy for RA and other inflammatory disorders.

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.

Metabolic effects of quercetin on inflammatory and autoimmune responses in rheumatoid arthritis are mediated through the inhibition of JAK1/STAT3/HIF-1α signaling

BACKGROUND

Rheumatoid arthritis, a chronic autoimmune disease, is characterized by synovial hyperplasia and cartilage erosion. Here, we investigated the potential mechanism of action of quercetin, the main component of flavonoids, in treating rheumatoid arthritis.

OBJECT

To examine the anti-arthritic effects of quercetin and elucidate the specific mechanisms that differentiate its metabolic effects on autoimmune and inflammatory responses at the synovial cell level.

METHODS

We created a collagen-induced arthritis (CIA) model in Wistar rats, which were administered quercetin (50 or 100 mg/kg) continuously for four weeks via stomach perfusion. The arthritis score, histopathological staining, radiological assessment, and serum biochemical parameters were used to study the impact of quercetin on disease improvement. Additionally, immunofluorescence was employed to detect JAK1/STAT3/HIF-1α expression in rat joints. Moreover, the effects of quercetin (20, 40, and 80 µmol/L) on the properties and behavior of synovial fibroblasts were evaluated in an in vitro MH7A cell model using flow cytometry, CCK8, and transwell assays. Further, the mRNA expression levels of inflammatory cytokines IL1β, IL6, IL17, and TNFα were assessed by quantitative real-time PCR. Glucose, lactate, lactate dehydrogenase, pyruvate, pyruvate dehydrogenase, and adenosine triphosphate assay kits were employed to measure the metabolic effects of quercetin on synovial fibroblasts. Finally, immunoblotting was used to examine the impact of quercetin on the JAK1/STAT3/HIF-1α signaling pathway in synovial fibroblasts.

RESULTS

In vivo experiments confirmed the favorable effects of quercetin in CIA rats, including an improved arthritis score and reduced ankle bone destruction, in addition to a decrease in the pro-inflammatory cytokines IL-1β, IL-6, IL-17, and TNF-α in serum. Immunofluorescence verified that quercetin may ameliorate joint injury in rats with CIA by inhibiting JAK1/STAT3/HIF-1α signaling. Various in vitro experiments demonstrated that quercetin effectively inhibits IL-6-induced proliferation of MH7A cells and reduces their migratory and invasive behavior, while inducing apoptosis and reducing the expression of the pro-inflammatory cytokines IL1β, IL6, IL17, and TNFα at the mRNA level. Quercetin caused inhibition of glucose, lactate, lactate dehydrogenase, pyruvate, and adenosine triphosphate and increased pyruvate dehydrogenase expression in MH7A cells. It was further confirmed that quercetin may inhibit energy metabolism and inflammatory factor secretion in MH7A cells through JAK1/STAT3/HIF-1α signaling.

CONCLUSIONS

Quercetin's action on multiple target molecules and pathways makes it a promising treatment for cartilage injury in rheumatoid arthritis. By reducing joint inflammation, improving joint metabolic homeostasis, and decreasing immune system activation energy, quercetin inhibits the JAK1/STAT3/HIF-1α signaling pathway to improve disease status.

Another Notch in the Belt of Rheumatoid Arthritis

Notch ligands and receptors, including JAG1/2, DLL1/4, and Notch1/3, are enriched on macrophages (MΦs), fibroblast-like synoviocytes (FLS), and/or endothelial cells in rheumatoid arthritis (RA) compared with normal synovial tissues (ST). Power Doppler ultrasound-guided ST studies reveal that the Notch family is highly involved in early active RA, especially during neovascularization. In contrast, the Notch family is not implicated during the erosive stage, evidenced by their lack of correlation with radiographic damage in RA ST. Toll-like receptors and tumor necrosis factor (TNF) are the common inducers of Notch expression in RA MΦs, FLS, and endothelial cells. Among Notch ligands, JAG1 and/or DLL4 are most inducible by inflammatory responses in RA MΦs or endothelial cells and transactivate their receptors on RA FLS. TNF plays a central role on Notch ligands, as anti-TNF good responders display JAG1/2 and DLL1/4 transcriptional downregulation in RA ST myeloid cells. In in vitro studies, TNF increases Notch3 expression in MΦs, which is further amplified by RA FLS addition. Specific disease-modifying antirheumatic drugs reduced JAG1 and Notch3 expression in MΦ and RA FLS cocultures. Organoids containing FLS and endothelial cells have increased expression of JAG1 and Notch3. Nonetheless, Methotrexate, interleukin-6 receptor (IL-6R) antibodies, and B cell blockers are mostly ineffective at decreasing Notch family expression. NF-κB, MAPK, and AKT pathways are involved in Notch signaling, whereas JAK/STATs are not. Although Notch blockade has been effective in RA preclinical studies, its small molecule inhibitors have failed in phase I and II studies, suggesting that alternative strategies may be required to intercept their function.

The role of Rhizoma Paridis saponins on anti-cancer: The potential mechanism and molecular targets

Cancer is a disease characterized by uncontrolled cell proliferation, leading to excessive growth and invasion that can spread to other parts of the body. Traditional Chinese medicine has made new advancements in the treatment of cancer, providing new perspectives and directions for cancer treatment. Rhizoma Paridis is a widely used Chinese herbal medicine with documented anti-cancer effects dating back to ancient times. Modern research has shown that Rhizoma Paridis saponins (RPS) have various pharmacological activities. RPS can inhibit cancer in multiple ways, such as suppressing tumor growth, inducing cell cycle arrest, promoting cell apoptosis, enhancing cell autophagy, inducing ferroptosis, reducing inflammation, inhibiting angiogenesis, as well as inhibiting metastasis and invasion, and these findings demonstrate the potent anti-cancer activity of RPS. Polyphyllin I, polyphyllin II, polyphyllin VI, and polyphyllin VII have been widely reported as the main active ingredients with anti-cancer properties. Polyphyllin D, polyphyllin E, and polyphyllin G have also been confirmed to possess strong anti-cancer activity in recent years. Therefore, this review dives deep into the molecular mechanisms underlying the anti-cancer effects of RPS to serve as a valuable reference for future scientific research and their potential applications in cancer treatment.

E3 ubiquitin ligase gene BIRC3 modulates TNF-induced cell death pathways and promotes aberrant proliferation in rheumatoid arthritis fibroblast-like synoviocytes

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease characterized by synovitis, degradation of articular cartilage, and bone destruction. Fibroblast-like synoviocytes (FLS) play a central role in RA, producing a significant amount of inflammatory mediators such as tumor necrosis factor(TNF)-α and IL-6, which promote inflammatory responses within the joints. Moreover, FLS exhibit tumor-like behavior, including aggressive proliferation and enhanced anti-apoptotic capabilities, which collectively drive chronic inflammation and joint damage in RA. TNF is a major pro-inflammatory cytokine that mediates a series of signaling pathways through its receptor TNFR1, including NF-κB and MAPK pathways, which are crucial for inflammation and cell survival in RA. The abnormal proliferation and anti-apoptotic characteristics of FLS in RA may result from dysregulation in TNF-mediated cell death pathways such as apoptosis and necroptosis. Ubiquitination is a critical post-translational modification regulating these signaling pathways. E3 ubiquitin ligases, such as cIAP1/2, promote the ubiquitination and degradation of target proteins within the TNF receptor complex, modulating the signaling proteins. The high expression of the BIRC3 gene and its encoded protein, cIAP2, in RA regulates various cellular processes, including apoptosis, inflammatory signaling, immune response, MAPK signaling, and cell proliferation, thereby promoting FLS survival and inflammatory responses. Inhibiting BIRC3 expression can reduce the secretion of inflammatory cytokines by RA-FLS under both basal and inflammatory conditions and inhibit their proliferation. Although BIRC3 inhibitors show potential in RA treatment, their possible side effects must be carefully considered. Further research into the specific mechanisms of BIRC3, including its roles in cell signaling, apoptosis regulation, and immune evasion, is crucial for identifying new therapeutic targets and strategies.

Multimodal PA/US imaging in Rheumatoid Arthritis: Enhanced correlation with clinical scores

BACKGROUND

Accurate assessment of Rheumatoid Arthritis (RA) activity remains a challenge. Multimodal photoacoustic/ultrasound (PA/US) joint imaging emerges as a novel imaging modality capable of depicting microvascularization and oxygenation levels in inflamed joints associated with RA. However, the scarcity of large-scale studies limits the exploration of correlating joint oxygenation status with disease activity.

OBJECTIVE

This study aimed to explore the correlation between multimodal PA/US imaging scores and RA disease activity, assessing its clinical applicability in managing RA.

METHODS

In this study, we recruited 111 patients diagnosed with RA and conducted examinations of seven small joints on their clinically dominant side using a PA/US imaging system. The PA and power Doppler ultrasound (PDUS) signals were semi-quantitatively assessed using a 0-3 grading system. The cumulative scores for PA and PDUS across these seven joints (PA-sum and PDUS-sum) were calculated. Relative oxygen saturation (So2) values of inflamed joints on the clinically dominant side were measured, and categorized into four distinct PA+So2 patterns. The correlation between PA/US imaging scores and disease activity indices was systematically evaluated.

RESULTS

Analysis of 777 small joints in 111 patients revealed that the PA-sum scores exhibited a strong positive correlation with standard clinical scores for RA, including DAS28 [ESR] (ρ = 0.682), DAS28 [CRP] (ρ = 0.683), CDAI (ρ = 0.738), and SDAI (ρ = 0.739), all with p < 0.001. These correlations were superior to those of the PDUS-sum scores (DAS28 [ESR] ρ = 0.559, DAS28 [CRP] ρ = 0.555, CDAI ρ = 0.575, SDAI ρ = 0.581, p < 0.001). Significantly, in patients with higher PA-sum scores, notable differences were observed in the erythrocyte sedimentation rate (ESR) (p < 0.01) and swollen joint count 28 (SJC28) (p < 0.01) between hypoxia and intermediate groups. Notably, RA patients in the hypoxia group exhibited higher clinical scores in certain clinical indices.

CONCLUSION

Multi-modal PA/US imaging introduces potential advancements in RA assessment, especially regarding So2 evaluations in synovial tissues and associated PA scores. However, further studies are warranted, particularly with more substantial sample sizes and in multi-center settings.

SUMMARY

This study utilized multi-modal PA/US imaging to analyze Rheumatoid Arthritis (RA) patients' synovial tissues and affected joints. When juxtaposed with traditional PDUS imaging, the PA approach demonstrated enhanced sensitivity, especially concerning detecting small vessels in thickened synovium and inflamed tendon sheaths. Furthermore, correlations between the derived PA scores, PA+So2 patterns, and standard clinical RA scores were observed. These findings suggest that multi-modal PA/US imaging could be a valuable tool in the comprehensive assessment of RA, offering insights not only into disease activity but also into the oxygenation status of synovial tissues. However, as promising as these results are, further investigations, especially in larger and diverse patient populations, are imperative.

KEY POINTS

⸸ Multi-modal PA/US Imaging in RA: This novel technique was used to assess the So2 values in synovial tissues and determine PA scores of affected RA joints.⸸ Correlation significantly with Clinical RA Scores: Correlations significantly were noted between PA scores, PA+So2 patterns, and standard clinical RA metrics, hinting at the potential clinical applicability of the technique.

An overview of multi-omics technologies in rheumatoid arthritis: applications in biomarker and pathway discovery

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease with a complex pathological mechanism involving autoimmune response, local inflammation and bone destruction. Metabolic pathways play an important role in immune-related diseases and their immune responses. The pathogenesis of rheumatoid arthritis may be related to its metabolic dysregulation. Moreover, histological techniques, including genomics, transcriptomics, proteomics and metabolomics, provide powerful tools for comprehensive analysis of molecular changes in biological systems. The present study explores the molecular and metabolic mechanisms of RA, emphasizing the central role of metabolic dysregulation in the RA disease process and highlighting the complexity of metabolic pathways, particularly metabolic remodeling in synovial tissues and its association with cytokine-mediated inflammation. This paper reveals the potential of histological techniques in identifying metabolically relevant therapeutic targets in RA; specifically, we summarize the genetic basis of RA and the dysregulated metabolic pathways, and explore their functional significance in the context of immune cell activation and differentiation. This study demonstrates the critical role of histological techniques in decoding the complex metabolic network of RA and discusses the integration of histological data with other types of biological data.

Deciphering the role of ferroptosis in rheumatoid arthritis: Synovial transcriptome analysis and immune infiltration correlation

The pathogenesis of rheumatoid arthritis (RA) remains elusive. The initiation of joint degeneration is characterized by the loss of self-tolerance in peripheral joints. Ferroptosis, a form of regulated cell death, holds significant importance in the pathophysiology of inflammatory arthritis, primarily due to iron accumulation and the subsequent lipid peroxidation. The present study investigated the association between synovial lesions and ferroptosis-related genes using previously published data from rheumatoid patients. Transcriptome differential gene analysis was employed to identify ferroptosis-related differentially expressed genes (FRDEGs). To validate FRDEGs and screen hub genes, we used weighted gene co-expression network analysis (WGCNA) and receiver operating characteristic (ROC) curves. Subsequently, immune infiltration analysis and single cell analysis were conducted to investigate the relationship between various synovial tissues cells and FRDEGs. The findings were further confirmed through reverse transcription-quantitative polymerase chain reaction (RT-qPCR), immunohistochemical staining, and immunofluorescence techniques. Upon intersecting DEGs with ferroptosis-related genes, we identified a total of 104 FRDEGs. Through the construction of a protein-protein interaction (PPI) network, we pinpointed the top 20 most highly concentrated genes as hub genes. Subsequent analyses using ROC curve and WGCNA validated eight FRDEGs: TIMP1, JUN, EGFR, SREBF1, ADIPOQ, SCD, AR, and FABP4. Immuno-infiltration analyses revealed significant infiltration of immune cell in RA synovial tissues and their correlations with the FRDEGs. Notably, TIMP1 demonstrated a positive correlation with various immune cell populations. Single-cell sequencing date of RA synovial tissue revealed predominant expression of TIMP1 is in fibroblasts. RT-qPCR, immunohistochemistry, and immunofluorescence analyses confirmed significant upregulation of TIMP1 at both mRNA and protein levels in RA synovial tissues and fibroblast-like synoviocytes (FLS). The findings provide novel insights into pathophysiology of peripheral immune tolerance deficiency in RA. The dysregulation of TIMP1, a gene associated with ferroptosis, was significantly observed in RA patients, suggesting its potential as a promising biomarker and therapeutic target.

Electroacupuncture improves articular microcirculation and attenuates cartilage hypoxia in a male rabbit model of knee osteoarthritis

Background and aim

Hypoxia of the cartilage has been considered as a potential pathogenic factor in knee osteoarthritis (KOA). Studies have shown that impaired blood perfusion of joint leads to cartilage hypoxia. Electroacupuncture (EA) has proven effects on pain relief and improving microcirculation. This study aimed to explore the effect of EA on articular microcirculation and cartilage anoxic and the underlying mechanisms.

Procedures

Videman's method was used for 6 weeks to establish the KOA model. EA intervention was performed in four points around the knee for 3 weeks after KOA modeling. The Lequesne MG score was used to assess ethology. We recorded the oxygen tension of synovial fluid and the synovial microcirculation in vivo. HE-staining was used to assess cartilage morphology, and immunohistochemistry (IHC), Western blotting, and RT-PCR were used to assess expression of the major glycolytic enzymes glucosetransporter1 (GLUT1), pyruvate kinase M2(PKM2), and lactate dehydrogenase A (LDHA). Enzyme-linked immunosorbent assay (Elisa) was used to detect lactate content.

Results and conclusion

There was a significant decrease in Lequesne MG score and improvement in Mankin score after EA intervention (P < 0.01), a significant increase in synovial microcirculation (P < 0.05) and synovial fluid oxygen tension (P < 0.01), and there was significant decrease in the expression of GLUT1, PKM2 and LDHA (P < 0.01) and lactate (P < 0.05). This study suggested that EA ameliorate cartilage hypoxia and regulate glycolytic metabolism in chondrocytes in KOA model rabbits by improving articular microcirculation and oxygen tension.

Mitochondrial Dysfunction and Fatigue in Sjögren's Disease

Objectives

Sjögren's disease (SjD) is a common exocrine disorder typified by chronic inflammation and dryness, but also profound fatigue, suggesting a pathological basis in cellular bioenergetics. In healthy states, damaged or dysfunctional mitochondrial components are broken down and recycled by mitophagy, a specialized form of autophagy. In many autoimmune disorders, however, evidence suggests that dysfunctional mitophagy allows poorly functioning mitochondria to persist and contribute to a cellular milieu with elevated reactive oxygen species. We hypothesized that mitophagic processes are dysregulated in SjD and that dysfunctional mitochondria contribute to overall fatigue. We sought to link fatigue with mitochondrial dysfunction directly in SjD, heretofore unexamined, and further sought to assess the pathogenic extent and implications of dysregulated mitophagy in SjD.

Methods

We isolated pan T cells via negative selection from the peripheral blood mononuclear cells of 17 SjD and 8 age-matched healthy subjects, all of whom completed fatigue questionnaires prior to phlebotomy. Isolated T cells were analyzed for mitochondrial oxygen consumption rate (OCR) and glycolysis using Seahorse, and linear correlations with fatigue measures were assessed. A mitophagy transcriptional signature in SjD was identified by reanalysis of whole-blood microarray data from 190 SjD and 32 healthy subjects. Differential expression analyses were performed by case/control and subgroup analyses comparing SjD patients by mitophagy transcriptional cluster against healthy subjects followed by bioinformatic interpretation using gene set enrichment analysis.

Results

Basal OCR, ATP-linked respiration, maximal respiration, and reserve capacity were significantly lower in SjD compared to healthy subjects with no observed differences in non-mitochondrial respiration, basal glycolysis, or glycolytic stress. SjD lymphocytic mitochondria show structural alterations compared to healthy subjects. Fatigue scores related to pain/discomfort in SjD correlated with the altered OCR. Results from subgroup analyses by mitophagic SjD clusters revealed highly variable inter-cluster differentially expressed genes (DEGs) and expanded the number of SjD-associated gene targets by tenfold within the same dataset.

Conclusion

Mitochondrial dysfunction, associated with fatigue, is a significant problem in SjD and warrants further investigation.

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.

SOX71, A Biocompatible Succinyl Derivative of the Triarylmethyl Radical OX071 for In Vivo Quantitative Oxygen Mapping Using Electron Paramagnetic Resonance

PURPOSE

This study aimed to develop a biocompatible oximetric electron paramagnetic resonance (EPR) spin probe with reduced self-relaxation, and sensitivity to oxygen for a higher signal-to-noise ratio and longer relaxation times at high oxygen concentration, compared to the reference spin probe OX071.

PROCEDURES

SOX71 was synthesized by succinylation of the twelve alcohol groups of OX071 spin probe and characterized by EPR at X-Band (9.5 GHz) and at low field (720 MHz). The biocompatibility of SOX71 was tested in vitro and in vivo in mice. A pharmacokinetic study was performed to determine the best time frame for EPR imaging. Finally, a proof-of-concept EPR oxygen imaging was performed on a mouse model of a fibrosarcoma tumor.

RESULTS

SOX71 was synthesized in one step from OX071. SOX71 exhibits a narrow line EPR spectrum with a peak-to-peak linewidth of 66 mG, similar to OX071. SOX71 does not bind to albumin nor show cell toxicity for the concentrations tested up to 5 mM. No toxicity was observed after systemic delivery via intraperitoneal injection in mice at twice the dose required for EPR imaging. After the injection, the probe is readily absorbed into the bloodstream, with a peak blood concentration half an hour, post-injection. Then, the probe is quickly cleared by the kidney with a half-life of ~ 45 min. SOX71 shows long relaxation times under anoxic condition (T1e = 9.5 µs and T2e = 5.1 µs; [SOX71] = 1 mM in PBS at 37 °C, pO2 = 0 mmHg, 720 MHz). Both the relaxation rates R1e and R2e show a decreased sensitivity to pO2, leading to twice longer relaxation times under room air conditions (pO2 = 159 mmHg) compared to OX071. This is ideal for oxygen imaging in samples with a wide range of pO2. Both the relaxation rates R1e and R2e show a decreased sensitivity to self-relaxation compared to OX071, with a negligible effect of the probe concentration on R1e. SOX71 was successfully applied to image oxygen in a tumor.

CONCLUSION

SOX71, a succinylated derivative of OX071 was synthesized, characterized, and applied for in vivo EPR tumor oxygen imaging. SOX71 is highly biocompatible, and shows decreased sensitivity to oxygen and self-relaxation. This first report suggests that SOX71 is superior to OX071 for absolute oxygen mapping under a broad range of pO2 values.

Redox Pathogenesis in Rheumatic Diseases

Despite being some of the most anecdotally well-known roads to pathogenesis, the mechanisms governing autoimmune rheumatic diseases are not yet fully understood. The overactivation of the cellular immune system and the characteristic development of autoantibodies have been linked to oxidative stress. Typical clinical manifestations, such as joint swelling and deformities and inflammation of the skin and internal organs, have also been connected directly or indirectly to redox mechanisms. The differences in generation and restraint of oxidative stress provide compelling evidence for the broad variety in pathology among rheumatic diseases and explain some of the common triggers and discordant manifestations in these diseases. Growing evidence of redox mechanisms in pathogenesis has provided a broad array of new potential therapeutic targets. Here, we explore the mechanisms by which oxidative stress is generated, explore its roles in autoimmunity and end-organ damage, and discuss how individual rheumatic diseases exhibit unique features that offer targets for therapeutic interventions.

MST1 knockdown inhibits osteoarthritis progression through Parkin-mediated mitophagy and Nrf2/NF-κB signalling pathway

Osteoarthritis (OA) is a complicated disease that involves apoptosis and mitophagy. MST1 is a pro-apoptotic factor. Hence, decreasing its expression plays an anti-apoptotic effect. This study aims to investigate the protective effect of MST1 inhibition on OA and the underlying processes. Immunofluorescence (IF) was used to detect MST1 expression in cartilage tissue. Western Blot, ELISA and IF were used to analyse the expression of inflammation, extracellular matrix (ECM) degradation, apoptosis and mitophagy-associated proteins. MST1 expression in chondrocytes was inhibited using siRNA and shRNA in vitro and in vivo. Haematoxylin-Eosin, Safranin O-Fast Green and alcian blue staining were used to evaluate the therapeutic effect of inhibiting MST1. This study discovered that the expression of MST1 was higher in OA patients. Inhibition of MST1 reduced inflammation, ECM degradation and apoptosis and enhanced mitophagy in vitro. MST1 inhibition slows OA progression in vivo. Inhibiting MST1 suppressed apoptosis, inflammation and ECM degradation via promoting Parkin-mediated mitophagy and the Nrf2-NF-κB axis. The results suggest that MST1 is a possible therapeutic target for the treatment of osteoarthritis as its inhibition delays the progression of OA through the Nrf2-NF-κB axis and mitophagy.

Microenvironment Responsive Hydrogel Exerting Inhibition of Cascade Immune Activation and Elimination of Synovial Fibroblasts for Rheumatoid Arthritis Therapy

Rheumatoid arthritis (RA) is a progressive autoimmune disease and drug therapy has been restricted due to poor therapeutic efficacy and adverse effects. In RA synovium, dendritic cells present self-antigens to activate cascade immune pathway. Furthermore, downstream macrophages secrete high levels of pro-inflammatory cytokines; Hyperplasia of activated synovial fibroblasts (FLS) is responsible for hypoxic synovium microenvironment, secretion of cytokines/chemokines and erosion of bone/cartilage tissues. Positive feedback loop of inflammation between macrophages and FLS independent of antigen-presentation is constructed. Herein, an injectable pH-sensitive peptide hydrogel encapsulating siRNA/Methotrexate-polyethyleneimine (siMP, including sip65MP, sip38MP, siCD86MP) and Bismuthene nanosheet/Methotrexate-polyethyleneimine (BiMP) is successfully developed. Among them, siCD86MP reduces protein level of co-stimulatory molecule CD86 while sip65MP and sip38MP separately inhibit NF-κB and MAPK-p38 pathways of macrophages and FLS to suppress secretion of cytokines and MMPs. Meanwhile, reduction in anti-apoptotic property of FLS induced by inhibition of NF-κB pathway has a synergistic effect with photodynamic therapy (PDT) and photothermal therapy (PTT) mediated by BiMP for FLS elimination, effectively ameliorating hypoxic synovium microenvironment. After being injected into synovium, hydrogel responds to acidic microenvironment and serves as a reservoir for sustained drug release and inherent retention capacity of which enables cationic nanoparticles to bypass tissue barrier for precise synovium targeting. This brand-new drug delivery system combines modulating cascade immune pathway from beginning to end by RNAi and eliminating FLS for improving synovium microenvironment by phototherapy together, providing a robust strategy for clinical RA treatment.

Combined ROS Sensitive Folate Receptor Targeted Micellar Formulations of Curcumin Effective Against Rheumatoid Arthritis in Rat Model

Introduction

Rheumatoid arthritis (RA) is an inflammatory immune-mediated disease that involves synovitis, cartilage destruction, and even joint damage. Traditional agents used for RA therapy remain unsatisfactory because of their low efficiency and obvious adverse effects. Therefore, we here established RA microenvironment-responsive targeted micelles that can respond to the increase in reactive oxygen species (ROS) levels in the joint and improve macrophage-specific targeting of loaded drugs.

Methods

We here prepared ROS-responsive folate-modified curcumin micelles (TK-FA-Cur-Ms) in which thioketal (TK) was used as a ROS-responsive linker for modifying polyethylene glycol 5000 (PEG5000) on the micellar surface. When micelles were in the ROS-overexpressing inflammatory microenvironment, the PEG5000 hydration layer was shed, and the targeting ligand FA was exposed, thereby enhancing cellular uptake by macrophages through active targeting. The targeting, ROS sensitivity and anti-inflammatory properties of the micelles were assessed in vitro. Collagen-induced arthritis (CIA) rats model was utilized to investigate the targeting, expression of serum inflammatory factors and histology change of the articular cartilage by micelles in vivo.

Results

TK-FA-Cur-Ms had a particle size of 90.07 ± 3.44 nm, which decreased to 78.87 ± 2.41 nm after incubation with H2O2. The micelles exhibited in vitro targeting of RAW264.7 cells and significantly inhibited inflammatory cytokine levels. Pharmacodynamic studies have revealed that TK-FA-Cur-Ms prolonged the drug circulation and exhibited augmented cartilage-protective and anti-inflammatory effects in vivo.

Conclusion

The unique ROS-responsive targeted micelles with targeting, ROS sensitivity and anti-inflammatory properties were successfully prepared and may offer an effective therapeutic strategy against RA.

Glycolysis, a driving force of rheumatoid arthritis

Resident synoviocytes and synovial microvasculature, together with immune cells from circulation, contribute to pannus formation, the main pathological feature of rheumatoid arthritis (RA), leading to destruction of adjacent cartilage and bone. Seeds, fibroblast-like synoviocytes (FLSs), macrophages, dendritic cells (DCs), B cells, T cells and endothelial cells (ECs) seeds with high metabolic demands undergo metabolic reprogramming from oxidative phosphorylation to glycolysis in response to poor soil of RA synovium with hypoxia, nutrient deficiency and inflammatory stimuli. Glycolysis provides rapid energy supply and biosynthetic precursors to support pathogenic growth of these seeds. The metabolite lactate accumulated during this process in turn condition the soil microenvironment and affect seeds growth by modulating signalling pathways and directing lactylation modifications. This review explores in depth the survival mechanism of seeds with high metabolic demands in the poor soil of RA synovium, providing useful support for elucidating the etiology of RA. In addition, we discuss the role and major post-translational modifications of proteins and enzymes linked to glycolysis to inspire the discovery of novel anti-rheumatic targets.

Proteomics analyses of human plasma reveal triosephosphate isomerase as a potential blood marker of methotrexate resistance in rheumatoid arthritis

OBJECTIVE

The objective of this study was to assess differentially expressed blood proteins between patients with active RA and patients in remission after MTX treatment, with the aim of identifying a biomarker of MTX resistance (MTXR).

METHODS

Two populations of RA patients treated with a stable dose of s.c. MTX for at least 3 months were constituted according to the DAS28: remission (DAS28 < 2.6; n = 24) and active disease (DAS28 > 3.2; n = 32). The two groups of RA patients were homogeneous regarding their epidemiological characteristics, except for the duration of treatment, which was longer in the remission group. After collection of a blood sample, plasma protein digestion was performed, followed by untargeted proteomics analysis. Then, a targeted analysis was performed to confirm the results of the untargeted approach.

RESULTS

Untargeted proteomics analysis revealed eight plasma proteins that were differentially expressed between the two groups of patients. Among them, triosephosphate isomerase (TPI-1) and glucose-6-phosphate isomerase (GPI), which are main actors in glycolysis, were found down-regulated in the active group. This result was confirmed for TPI-1 in the targeted proteomics analysis.

CONCLUSION

A first step was achieved in the search for biomarkers of MTXR, with the identification of two actors in glycolysis (TPI-1 and GPI). The next step will be to confirm these results in a larger cohort, including samples from treatment-naive patients, to assess the predictive potential of these protein markers.