Curcumin-based nanotechnology approaches and therapeutics in restoration of autoimmune diseases

Autoimmune diseases usually arise as a result of an aberrant immune system attack on normal tissues of the body, which leads to a cascade of inflammatory reactions. The immune system employs different types of protective and anti-inflammatory cells for the regulation of this process. Curcumin is a known natural anti-inflammatory agent that inhibits pathological autoimmune processes by regulating inflammatory cytokines and their associated signaling pathways in immune cells. Due to the unstable nature of curcumin and its susceptibility to either degradation, or metabolism into other chemical entities (i.e., metabolites), encapsulation of this agent into various nanocarriers would appear to be an appropriate strategy for attaining greater beneficial effects from curcumin as it pertains to immunomodulation. Many studies have focused on the design and development of curcumin nanodelivery systems (micelles, dendrimers, and diverse nanocarriers) and are summarized in this review in order to obtain greater insight into novel drug delivery systems for curcumin and their suitability for the management of autoimmune diseases.

Seronegative rheumatic arthritis has milder inflammation and bone erosion in an ultrasound study of disease-modifying anti-rheumatic drugs (DMARDs)-naïve Chinese cohort

Background

Compared with the seropositive rheumatic arthritis (sp-RA), seronegative rheumatic arthritis (sn-RA) lacks ultrasound (US) research. It is unknown whether sn-RA patients had more severe synovitis than sp-RA ones at the same level of swollen joint counts (SJCs). We designed the US study to find out the answers.

Methods

All cases satisfied the 2010 classification criteria, first diagnosed and disease-modifying anti-rheumatic drugs (DMARDs) naïve with the characteristics of abnormal swelling or pain in the wrist, proximal interphalangeal (PIPs), and metacarpophalangeal (MCPs) joints. Demographic data was collected. US examinations, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), visual analogue scale scores (VASs), patient global assessment (PGA), physician’s global assessment (PhGA), disease activity score of 28 joints (DAS28), and van der Heijde-modified Sharp score (vdHSS) were used to evaluate the disease activity among these groups. Anticitrullinated peptide antibody (ACPA), rheumatoid factor (RF) and SJCs were used to divide the patients into 3 groups, which were defined as follows: Group A, sp-RA (positive RF and/or ACPA) with SJC >10; Group B, sp-RA with SJC ≤10; and Group C, sn-RA (all negative RF and ACPA with SJC >10 due to the criteria).

Results

A total of 139 cases were recruited. Fifty-six were Group A, 54 were Group B, and 29 were Group C. All indexes above and the total US scores were significantly lower in Group C than Group A (both groups with SJC >10) (ESR, CRP, VASs, PGA, PhGA, DAS28, vdHSS, US total score respectively: 58.8 vs. 37.5, P=0.009; 37.5 vs. 17.8, P=0.008; 61.7 vs. 52.8, P=0.032; 62.2 vs. 53.9, P=0.031; 59.8 vs. 48.3, P=0.029; 6.92 vs. 5.56, P=0.000; 61.7 vs. 44.5, P=0.023; 31.4 vs. 20.9, P=0.000). The difference of the total US scores above was mostly contributed by the symptoms of synovitis. The total US scores were prominently lower in Group C with the duration over 2 years (2–5 years, >5 years, respectively compared to <2 years: 16.3 vs. 27.4, P=0.044; 16.5 vs. 27.4, P=0.048), and vdHSS were remarkably higher in almost all groups with a duration of over 5 years. For the patients with a duration over 2 years, bone erosions occurred earlier in sp-RA than in sn-RA patients.

Conclusions

Sn-RA patients had milder synovitis than sp-RA ones at the same extent of disease activity. In addition, sn-RA had delayed progress of bone erosion than the sp-RA group.

Comparison of immune cells and diagnostic markers between spondyloarthritis and rheumatoid arthritis by bioinformatics analysis

Background

Spondyloarthritis (SpA) and rheumatoid arthritis (RA) are chronic autoimmune diseases, but they are usually difficult to distinguish in the early stage of the diseases. The purpose of this study is to explore the differences of immune mechanism and diagnostic markers through bioinformatics analysis.

Methods

First, microarray datasets from patients with SpA, RA and normal controls were obtained from the Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) between groups were identified in R software. Functional and pathway enrichment of DEGs were analyzed by David database. Then, we screened the hub genes using Cytoscape plugin, and constructed the protein–protein interaction (PPI) network and heatmap of hub genes. After that, CIBERSORT was used to evaluate the differences and connections of immune cells in SpA and RA, and screened out diagnostic markers. Correlation analysis was used to analyze the relationship between immune cells and diagnostic markers. Finally, quantitative real-time polymerase chain reaction (qRT‐PCR) was used to verify the effectiveness of immunodiagnostic markers.

Results

We obtained three datasets, from which we can see that the functional enrichment of DEGs is mainly in cell chemotaxis, lymphocyte activation, primary immunodeficiency and other immune responses. The difference of immune cells between SpA, RA and normal control was concentrated in B, T lymphocytes cells, macrophages and dendritic cells. C19orf12 + S1PR3 is most associated with these immune cells and S1PR3 can be used as a diagnostic marker of this kind of immune diseases. In addition, MZB1 + XIST is closely related to T cells, NK cells and dendritic cells, and is expected to be used as a marker to distinguish the two diseases.

Conclusion

Although the clinical manifestations of SpA and RA are similar, the pathogenesis is different. The screening of immune cells and diagnostic markers provides a more accurate target for the treatment of this kind of diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03390-y.

Granulomatous Diseases of the Central Nervous System

PURPOSE OF REVIEW

To discuss the pathophysiology, key clinical features, necessary diagnostic evaluation, and current treatment regimens for granulomatous diseases of the central nervous system.

RECENT FINDINGS

The diagnosis and management of granulomatous disease of the central nervous system has been revolutionized by advances in diagnostic imaging. Nevertheless, tissue and/or cerebrospinal fluid (CSF) sampling remains necessary to establish the diagnosis in most cases. Establishing a specific diagnosis is critical because treatment selection needs to focus on the granulomatous process centering on either antibiotic or immunosuppressive agents. Particular for non-infectious granulomatous disease more aggressive immunotherapies may help in clinical outcome. There are multiple non-infectious and infectious etiologies for granulomatous disease of the central nervous system. Clinical manifestations result from local structural invasion of granulomas or granulomatous inflammation of the blood vessels and meninges. Rapid diagnosis and specific treatment is essential.

Possible roles of anti-type II collagen antibody and innate immunity in the development and progression of diabetic retinopathy

The pathogenesis of both diabetic retinopathy (DR) and rheumatoid arthritis (RA) has recently been considered to involve autoimmunity. Serum and synovial fluid levels of anti-type II collagen antibodies increase early after the onset of RA, thus inducing immune responses and subsequent hydrarthrosis and angiogenesis, which resemble diabetic macular edema and proliferative DR (PDR), respectively. We previously reported that DR is also associated with increased serum levels of anti-type II collagen antibodies. Retinal hypoxia in DR may induce pericytes to express type II collagen, resulting in autoantibody production against type II collagen. As the result of blood-retinal barrier disruption, anti-type II collagen antibodies in the serum come into contact with type II collagen around the retinal vessels. A continued loss of pericytes and type II collagen around the retinal vessels may result in a shift of the immune reaction site from the retina to the vitreous. It has been reported that anti-inflammatory M2 macrophages increased in the vitreous of PDR patients, accompanied by the activation of the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, a key regulator of innate immunity. M2 macrophages promote angiogenesis and fibrosis, which might be exacerbated and prolonged by dysregulated innate immunity.

Exploring the translational potential of clusterin as a biomarker of early osteoarthritis

BACKGROUND

Clusterin (CLU; also known as apolipoprotein J) is an ATP-independent holdase chaperone that prevents proteotoxicity as a consequence of protein aggregation. It is a ∼60 kDa disulfide-linked heterodimeric protein involved in the clearance of cellular debris and the regulation of apoptosis. CLU has been proposed to protect cells from cytolysis by complement components and has been implicated in Alzheimer's disease due to its ability to bind amyloid-β peptides and prevent aggregate formation in the brain. Recent studies suggest that CLU performs moonlighting functions. CLU exists in two major forms: an intracellular form and a secreted extracellular form. The intracellular form of CLU may suppress stress-induced apoptosis by forming complexes with misfolded proteins and facilitates their degradation. The secreted form of CLU functions as an extracellular chaperone that prevents protein aggregation.

METHODS

In this review, we discuss the published literature on the biology of CLU in cartilage, chondrocytes, and other synovial joint tissues. We also review clinical studies that have examined the potential for using this protein as a biomarker in synovial and systemic fluids of patients with rheumatoid arthritis (RA) or osteoarthritis (OA).

RESULTS

Since CLU functions as an extracellular chaperone, we propose that it may be involved in cytoprotective functions in osteoarticular tissues. The secreted form of CLU can be measured in synovial and systemic fluids and may have translational potential as a biomarker of early repair responses in OA.

CONCLUSION

There is significant potential for investigating synovial and systemic CLU as biomarkers of OA. Future translational and clinical orthopaedic studies should carefully consider the diverse roles of this protein and its involvement in other comorbidities. Therefore, future biomarker studies should not correlate circulating CLU levels exclusively to the process of OA pathogenesis and progression. Special attention should be paid to CLU levels in synovial fluid.

THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE

There is significant potential for investigating synovial and systemic CLU as a predictive biomarker of osteoarthritis (OA) progression and response to novel treatments and interventions. Given that CLU plays diverse roles in other comorbidities such as rheumatoid arthritis (RA) and obesity, future translational and clinical orthopaedic biomarker studies should not directly correlate circulating CLU levels to the process of OA pathogenesis and progression. However, special attention should be paid to CLU levels in synovial fluid. The cytoprotective properties of CLU may support the implementation of regenerative strategies and new approaches for developing targeted therapeutics for OA.

Association between serum amyloid A and rheumatoid arthritis: A systematic review and meta-analysis

BACKGROUNDS

Consistent correlation of serum amyloid A (SAA) to rheumatoid arthritis (RA) is not completely established. The present study is to systematically summarize their relationship.

METHODS

Publications up to may 2021 were examined using key terms in the PubMed, Cochrane Library, Embase and China national knowledge infrastructure (CNKI) databases.

RESULTS

The total 33 studies, involving in 3524 RA cases and 3537 normal participants, were included. The pooled result indicated that the SAA level in the RA group was markedly higher than that in the control group [standardized mean difference (SMD) = 0.80, 95% CI (0.51, 1.08)]. By stratified analyses, the concentration of SAA was found to be gradually increased with the aggravation of RA. Additionally, the meta-analysis of correlation demonstrated that SAA levels were positively associated with the levels of disease activity score 28 (DAS28) [r = 0.55, 95% CI (0.15, 0.94)], erythrocyte sedimentation rate (ESR) [r = 0.65, 95% CI (0.53, 0.76)], C-reactive protein (CRP) [r = 0.92, 95% CI (0.57, 1.57)], rheumatoid factor (RF) [r = 0.24, 95% CI (0.09, 0.39)], interleukin 4 (IL-4) [r = 0.54, 95% CI (0.30, 0.78)], interleukin 6 (IL-6) [r = 0.46, 95% CI (0.27, 0.65)], interleukin 10 (IL-10) [r = 0.53, 95% CI (0.29, 0.77)], interleukin 17 (IL-17) [r = 0.52, 95% CI (0.27, 0.77)], and anti-cyclic citrullinated peptide antibody (A-CCP) [r = 0.32, 95% CI (0.15, 0.50)], but inversely linked with the levels of hemoglobin [r=-0.51, 95% CI (-0.84, -0.18)]. Furthermore, the allele of SAA 1.3 was actively related with increased risks of RA [OR=1.30, 95% CI (1.02, 1.65)] and of RA with amyloidosis [OR=2.06, 95% CI (1.63, 2.60)]. Besides, the genotype of SAA 1.3/1.3 was positively connected with the risks of RA [OR=1.56, 95% CI (1.00, 2.43)] and of RA with amyloidosis [OR=4.47, 95% CI (2.70, 7.41)].

CONCLUSIONS

High levels of SAA might be associated with elevated risk of RA, and the concentration of SAA might be gradually increased with the aggravation of RA. Moreover, high levels of SAA might play a vital role in RA by enhancing the levels of DAS28, ESR, CRP, RF, IL-4, IL-6, IL-10, IL-17 and A-CCP, or by attenuating hemoglobin levels. More importantly, the allele of SAA 1.3 and genotype of SAA 1.3/1.3 might be the risk factor of RA and of RA with amyloidosis.

LncRNA THRIL is involved in the proliferation, migration, and invasion of rheumatoid fibroblast-like synoviocytes

Background

Fibroblast-like synoviocytes (FLSs), which can migrate and directly invade the cartilage and the bone, are crucial players in joint damage in rheumatoid arthritis (RA). Nevertheless, the detailed mechanisms underlying the aberrant activation of RA FLSs remain unclear. Several studies have attempted to explore the relationship between long non-coding RNAs (lncRNAs) and RA pathology; however, the role of lncRNAs in RA is unknown. The present study aimed to determine the functions of tumor necrosis factor-α and heterogeneous nuclear ribonucleoprotein L-related immunoregulatory lincRNA (THRIL) in RA FLSs migration and invasion.

Methods

Small interfering RNA targeting THRIL or lentivirus overexpressing THRIL was used to knockdown or overexpress THRIL. Quantitative reverse transcription polymerase chain reaction (PCR) was employed for the detection of RNA expression. The proliferation rate of RA FLSs was measured using a 5-ethynyl-2'-deoxyuridine (EdU) incorporation assay. Migration and invasion were detected using a transwell chamber. Downstream targets were identified using a human cell cycle real-time PCR array and a human cell motility real-time PCR array.

Results

A significant decrease in THRIL expression was found in RA FLSs compared with cells from healthy control (HC)patients. THRIL is mainly localized in the nucleus. Knockdown of THRIL increased the proliferation, migration, and invasion of RA FLSs. In contrast, THRIL overexpression had the opposite effect. THRIL knockdown increased interleukin-1β (IL-1β)-triggered expression of matrix metalloproteinase (MMP)-1, MMP-3, and MMP-13. THRIL overexpression led to a significant decrease in MMP-13 expression in response to stimulation with IL-1β. Furthermore, we observed that the expression levels of cyclin-dependent kinase 1 (CDK1) and G2 and S phase-expressed-1 (GTSE1), both of which are associated with cellular mobility and proliferation, were downregulated with THRIL overexpression.

Conclusions

Reduced expression of lncRNA THRIL represses the proliferation, migration, and invasion of RA FLSs, suggesting that lncRNA THRIL might be a potential target for RA therapy.

Exploring the therapeutic promise of targeting Rho kinase in rheumatoid arthritis

Rheumatoid arthritis (RA) is a prevalent systemic autoimmune disease caused by dysregulated inflammatory reactions, T lymphocyte invasion into the joints, and articular thickening. Immune cells, primarily tumor necrosis factor-alpha (TNF-α) and chemokines (interleukin or IL-1), which are predominantly generated by activated macrophages cells, have also been involved with the pathogenesis of rheumatoid arthritis. Rho GTPases are integral factors of biochemical cascades utilized by antigens, and also by cellular receptors, cytokines, and chemokines, to modulate inflammatory reactions, according to growing data. The Rho family is a group of G proteins that govern a variety of biological and physiological activities such as mobility, actin stress fiber production, growth, and polarity. Research suggests that the Rho A and Rho-associated coiled-coil kinase (ROCK) regulatory cascade could be essential in several autoimmune conditions, including RA. ROCK is activated in the synovial of rheumatoid arthritis patients, while the blocking of ROCK with fasudil could also decrease IL-6, TNF-α, and IL-1. This review covers current developments in understanding the overactivation of Rho enzyme activity in RA suppressed by ROCK inhibitors which can be utilized for the treatment of autoimmune disease. We offer an outline of the function of ROCK inhibitors in immune cells and discuss findings which emphasize the rising participation of this category of kinases within the pathological process of autoimmune disorders. Assuming the potential ability of ROCK as a therapeutic, we define approaches that might be used to inhibit Rho kinase activity in rheumatoid disorders.

The protein-protein interaction between connective tissue growth factor and annexin A2 is relevant to pannus formation in rheumatoid arthritis

Background

Connective tissue growth factor (CTGF)-induced angiogenesis is a crucial factor in rheumatoid arthritis (RA), but CTGF-interacting protein and related molecular mechanism of their interaction have not been fully elucidated.

Methods

CTGF-interacting proteins were identified through the LC-MS/MS analysis of the Co-IP products from fibroblast-like synoviocyte (FLS) lysates, and the interaction between CTGF and annexin A2 (ANXA2) was further confirmed through Co-IP and BiFC assay. The binding domain, mutant, mechanism, and angiogenesis function were assessed by homology modeling, molecular docking, MTT, cell scratch, tube formation, and chick chorioallantoic membrane (CAM) assays. Additionally, severe combined immunodeficiency (SCID) mouse co-implantation model was constructed to confirm the effect of ANXA2/CTGF-TSP1 in the process of RA in vivo.

Results

ANXA2 was identified and verified as an interaction partner of CTGF for the first time by Co-IP and LC-MS/MS analysis. Co-localization of CTGF and ANXA2 was observed in RA-FLS, and direct interaction of the TSP-1 domain of CTGF and ANXA2 was determined in HEK293T cells. The spatial conformation and stable combination of the ANXA2/CTGF-TSP1 complex were assessed by homology modeling in the biomimetic environment. The function of the ANXA2/CTGF-TSP1 complex was proved on promoting FLS proliferation, migration, and angiogenesis in vitro and deteriorating FLS invasion and joint damage in SCID mice.

Conclusions

TSP-1 is the essential domain in CTGF/ANXA2 interaction and contributes to FLS migration and pannus formation, inducing the process of RA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02656-y.

lncRNA GAS5 suppresses rheumatoid arthritis by inhibiting miR-361-5p and increasing PDK4

Rheumatoid arthritis (RA) is an inflammatory disease that causes hyperplasia of synovial tissue and cartilage destruction. This research was to investigate the effects of lncRNA GAS5/miR-361-5p/PDK4 on rheumatoid arthritis. By qRT-PCR, GAS5 and PDK4 were found to be overexpressed in synovial tissue, fibroblast-like synoviocytes of RA patients and LPS-induced chondrocytes, while the miR-361-5p expression was significantly reduced. GAS5 overexpression resulted in a decrease in the proliferation and Bcl-2 protein expression, and an increase in the Bax protein level. On the contrary, miR-361-5p sponged by GAS5 could accelerate chondrocyte proliferation, inhibit apoptosis. PDK4 targeted by miR-361-5p could inhibit RA, and partially eliminated the effect of miR-361-5p on RA. Our study suggested that GAS5 suppressed RA by competitively adsorbing miR-361-5p to modulate PDK4 expression.

Stress fracture of proximal tibia after proximal fibula osteotomy: A case report

Introduction

Proximal fibula osteotomy (PFO) is a new method for treating medial compartment osteoarthritis of the knee, which is based on the theory of differential settlement (nonuniform settlement). This procedure has been widely recognized for its advantages of relative simplicity, low rate of postoperative complications, and low postoperative costs. Stress fracture of the proximal tibia after PFO has not been previously reported.

Case presentation

We report a 62-year-old woman with chronic rheumatoid arthritis (RA) underwent left PFO for chronic knee pain, who developed a stress fracture of the proximal tibia more than 1 year after PFO.

Clinical discussion

In the early stage of proximal tibia stress fracture, due to the concealment of radiography manifestations, doctors from another hospital performed total knee arthroplasty (TKA) for the patient. They ignored the treatment of stress fracture of the proximal tibia, and the stress fracture was further aggravated after surgery. Six months later, the patient underwent open reduction and internal fixation with a plate and screw in the left proximal tibia fracture at our hospital. The patient was followed up at the hospital three months after open reduction, and the proximal tibia stress fracture began to heal.

Conclusion

RA is usually not confined to the medial compartment and its pathogenesis is different from that of osteoarthritis. Therefore, PFO is not an appropriate procedure for this type of patient.

•

Stress fracture of proximal tibia after PFO has not been previously reported.

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This case is extremely rare of a stress fracture of the proximal tibia more than 1 year after PFO.

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RA is usually not confined to the medial compartment that PFO is not an appropriate procedure for this type of patient.

Increased risk of periodontitis occurrence in patients with rheumatoid arthritis and its association with the levels of IL-1β and TNF-α in gingival crevicular fluid

BACKGROUND

Periodontitis (PD) is a chronic inflammatory disease caused by infection of the periodontal supporting tissues. Clinical studies have reported that rheumatoid arthritis (RA) patients have a higher prevalence of PD. This study aimed to explore the correlation between RA and PD.

METHODS

A total of 307 RA patients (RA group) and 324 healthy individuals (control group) who received physical examinations during the same period were recruited to this study. The incidence of PD in the two groups was analyzed, and the periodontal disease index (PDI) and bleeding on probing (BOP) were recorded. Then, 42 RA patients with PD and 56 control group patients with PD were selected for further analysis. Enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of interleukin 1β (IL-1β) and tumor necrosis factor-α (TNF-α) in the gingival crevicular fluid (GCF) of the two groups. For patients with both RA and PD, the level of serum C-reactive protein (CRP) and the duration of morning stiffness were also recorded.

RESULTS

The prevalence of PD in the RA group (51.5%) was significantly higher than that in the control group (31.2%), and the prevalence of PD also increased notably with the increase of age and the duration of the disease in RA patients. The levels of TNF-α and IL-1β in the PDI and the GCF in the concurrent RA and PD group were significantly higher than those in the PD group (P<0.05). Partial correlation analysis showed that TNF-α in the GCF positively correlated with the BOP of patients with RA and PD. Multiple linear regression analysis showed that the level of TNF-α in the GCF and serum CRP were independent influencing factors of the level of IL-1β in the GCF (the r values were 1.074 and 3.851, respectively; P<0.01).

CONCLUSIONS

The presence of RA can increase risk of PD occurrence and is positively correlated with the levels of IL-1β and TNF-α in the GCF.

Bioinformatics-based study to identify immune infiltration and inflammatory-related hub genes as biomarkers for the treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease whose principal pathological change is aggressive chronic synovial inflammation; however, the specific etiology and pathogenesis have not been fully elucidated. We downloaded the synovial tissue gene expression profiles of four human knees from the Gene Expression Omnibus database, analyzed the differentially expressed genes in the normal and RA groups, and assessed their enrichment in functions and pathways using bioinformatics methods and the STRING online database to establish protein-protein interaction networks. Cytoscape software was used to obtain 10 hub genes; receiver operating characteristic (ROC) curves were calculated for each hub gene and differential expression analysis of the two groups of hub genes. The CIBERSORT algorithm was used to impute immune infiltration. We identified the signaling pathways that play important roles in RA and 10 hub genes: Ccr1, Ccr2, Ccr5, Ccr7, Cxcl5, Cxcl6, Cxcl13, Ccl13, Adcy2, and Pnoc. The diagnostic value of these 10 hub genes for RA was confirmed using ROC curves and expression analysis. Adcy2, Cxcl13, and Ccr5 are strongly associated with RA development. The study also revealed that the differential infiltration profile of different inflammatory immune cells in the synovial tissue of RA is an extremely critical factor in RA progression. This study may contribute to the understanding of signaling pathways and biological processes associated with RA and the role of inflammatory immune infiltration in the pathogenesis of RA. In addition, this study shows that Adcy2, Cxcl13, and Ccr5 have the potential to be biomarkers for RA treatment.

Dissociation between 2-[18F]fluoro-2-deoxy-D-glucose positron emission computed tomography, ultrasound and clinical assessments in patients with non-severe rheumatoid arthritis, including remission

Background

Inflammation of patients joints with severe disease activity of rheumatoid arthritis (RA) has already been visualized and quantified by 2-[¹⁸F]fluoro-2-deoxy-D-glucose positron emission computed tomography ([¹⁸F] FDG PET/CT), but little is known about the metabolic status and its relationship with clinical and ultrasonography (US) metrology in patients with low/moderate activity or in remission.

Methods

Clinical assessments [based on 28-joint disease activity score (DAS₂₈-CRP) and Clinical Disease Activity Index (CDAI)], [¹⁸F] FDG PET/CT, US and X-ray were performed on 63 RA patients classified into remission or low/moderate or severe disease activity groups. PET/CT was visually and then semi-quantitatively analysed by determining the standardized uptake value (SUV) of positive joints.

Results

Of the 1764 joints, 21.1% were tender only, 13.7% swollen only, 27.6% tender or swollen, 7.3% tender and swollen, 20.5% PET/CT-positive and 8.6% US-positive. PET and US measurements were correlated, albeit with poor concordance. The positive predictive value of PET/CT for clinical evaluation (tender and/or swollen) was low, whereas its negative predictive value was high. Highly significant differences were found with the number of PET/CT-positive joints and with cumulative SUV between “severe” and “non-severe” patients (including those in remission and those with low/moderate activity) and not between those classified as “remission” and “non-remission” or “remission” and “low/moderate activity”. Moreover, the correlation between PET/CT measurements and clinical activity was positive only in the CDAI severe disease group. In patients in remission or with low/moderate activity, only 20–30% of joints were PET/CT-negative. In remission, PET/CT and US were positive in different joints, and PET/CT-positive but US-negative joints mainly exhibited RA (38.1%) or normal (49.2%) and not osteoarthritic (12.7%) X-ray patterns.

Conclusions

[¹⁸F] FDG PET/CT was effective at distinguishing patients with severely active disease from other patients. In non-severe RA patients, including those in remission, PET/CT results are discordant from US and clinical observations. A longitudinal analysis is needed to explore the clinical relevance of such infra-clinical disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41927-021-00196-1.

LPS induces fibroblast-like synoviocytes RSC-364 cells to pyroptosis through NF-κB mediated dual signalling pathway

Rheumatoid arthritis (RA) is a chronic, progressive, and systemic inflammatory joint disease characterized by synovial inflammation and joint damage. Abnormal activation of fibroblast-like synoviocytes is an initial event of synovial inflammation and joint damage, which can significantly aggravate the progression of RA. Clinical studies have shown that synovitis may be associated with pyroptosis. Therefore, this study is mainly aim for exploring the underlying mechanisms of relationship between inflammation and pyroptosis during synovitis. A cell model of synovitis was constructed by stimulating synovial fibroblasts RSC-364 cells with lipopolysaccharide (LPS). In vitro, we found that LPS can induce pyroptosis of synovial fibroblasts through NOD-like receptor pyrin domain-3/caspase-1/gasdermin D and caspase-3/gasdermin E two signaling pathways, and these two signaling pathways can promote each other. In addition, NF-κB signaling pathway, as the upstream of these two pathways, is involved in regulating the pyroptosis of synovial fibroblast. These results suggest that pyroptosis may be triggered during the occurrence of RA. We hope to provide a new perspective for the study of RA and a new therapeutic target for clinical treatment of RA.

Interplay of Microbiota and Citrullination in the Immunopathogenesis of Rheumatoid Arthritis

Microbiota is a balanced ecosystem that has important functions to the host health including development, defense, digestion, and absorption of dietary fibers and minerals, vitamin synthesizes, protection, and training the host immune system. On the other hand, its dysbiosis is linked to many human diseases such as rheumatoid arthritis (RA). The RA is an inflammatory autoimmune disorder caused by genetic and environmental factors; microbiota may be considered as a risk environmental factor for it. Citrullination is a post-translation modification (PMT) that converts the amino acid arginine to amino acid citrulline in certain proteins. These citrullinated proteins are recognized as a foreign antigen by the immune system resulting in the upregulation of inflammatory action such as in RA. The current work highlights the effect of both gut and oral microbiota dysbiosis on the development of RA, as well as discusses how the alteration in microbiota composition leads to the overgrowth of some bacterial species that entangled in RA pathogenicity. The evidence suggested that some oral and gut microbial species such as Porphyromonas gingivalis and Prevotella copri, respectively, contribute to RA pathogenesis. During dysbiosis, these bacteria can mediate the citrullination of either human or bacteria proteins to trigger an immune response that leads to the generation of autoantibodies.

Radiocapitellar arthroplasty

This article sets out the evidence demonstrating that the clinical need for a prosthetic arthroplasty designed specifically for the radiocapitellar joint has been underestimated. The prevalence of radiocapitellar degenerative change requiring treatment is discussed and the relationship between 'isolated' radiocapitellar joint arthritis and more generalised elbow arthritis is explained. Current literature now supports our view that radiocapitellar joint arthroplasty is not only an effective long-term solution for patients with localised radiocapitellar arthritis but also for those patients with more severe degenerative changes involving the elbow joint irrespective of their cause. We consider that is important to avoid resection of the radial head and therefore that resurfacing implants rather than joint replacement implants are more likely to provide a good longterm outcome for patients with elbow arthritis.

Systematic investigation on the anti-rheumatoid arthritis material basis and mechanism of Juan Bi Tang. Part 1: Integrating metabolic profiles and network pharmacology

Previously, our cooperative team confirmed the chemical composition and anti-rheumatoid arthritis (RA) efficacy of Juanbi-Tang (JBT), a clinically and historically used traditional Chinese medicine formula, in two model animals. In this study, we developed an in vivo-in silico strategy to elucidate the anti-RA material basis and mechanism of JBT. With the aid of high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (HPLC-Q-TOF), the metabolic profiles were investigated in normal and collagen-induced arthritis RA rats following oral administration of JBT. Based on the absorbed constituents in RA rats, network pharmacology was employed to predict the anti-RA mechanisms, followed by molecular docking validation. Consequently, there were 18 absorbed compounds with 6 chemical structures, which were absolutely identified by matching with standard compounds in plasma, and 17 generated metabolites involved of 7 biotransformation pathways, including glucuronidation, sulfation, hydroxylation, deglycosylation, methylation, taurine, and glycine conjugation. Moreover, RA disease affected the absorption and metabolism of the constituents in JBT, given the undetected 2 absorbed compounds and 4 metabolites in RA rats. The analysis of network pharmacology indicated that those absorbed compounds in JBT may fight against RA through the MAPK, FoxO, and Rap1 pathways. Molecular docking also validated these results. Overall, this is the first study to describe the metabolic profiles of JBT-treated healthy and RA rats, and it provides a possible anti-RA mechanism through multiple absorbed compounds and targets by network pharmacology.

Autoantibodies to extractable nuclear antigens (ENAs) pattern in rheumatoid arthritis patients: Relevance and clinical implications

OBJECTIVES

To study the frequency of different autoantibodies to extractable nuclear antigens (ENAs) in rheumatoid arthritis (RA) patients and to correlate findings with clinical manifestations, disease activity and radiological damage.

METHODS

A total of 230 RA patients were included and 75 healthy controls. In all patients rheumatological assessment was done and routine laboratory investigations and immune profile were performed in both patients and controls, including: RF, ACPA, ANA and anti-ENAs (Ro/SSA, La/SSB, U1-RNP, anti-Jo-1 and anti-Sm). Radiological damage was scored using Sharp/van der Heijde, and disease activity was evaluated by DAS28-ESR and DAS28-CRP.

RESULTS

RF was positive in 101 (43.9%), ACPA in 220 (95.7%), ANA in 58 (25.2%), anti Ro in 31 (13.5%), anti-La in 10 (4.3%), anti-Jo1 in 5 (2.2%) and anti-RNP in 2 (0.9%). Anti-Ro/SSA positively correlated with sicca symptoms (p=.02), RF titer (p<.001), ANA (p<.001), DAS28-ESR (p=.026), and DAS28-CRP (p=.003). Anti-La antibodies correlated positively with SJC (p=.001), TJC (p=.001), ANA (p<.001), DAS-28 ESR (p=.007). Anti-Jo-1 correlated positively with interstitial lung disease (ILD) (p≤.001), RF titer (p=.037) and ANA (p≤.001). Anti-RNP antibodies correlated positively with disease duration (p≤.001), ACPA titer (p≤.001) and ANA (p=.014). In the controls ANA was positive in two (2.7%), anti-Ro in three (4%), and none of the controls tested positive for other autoantibodies.

CONCLUSIONS

In RA patients, positive ANA is frequent and positively associated with anti-Ro, anti-La and anti-Jo1 autoantibodies. Screening for autoantibodies against other anti-ENAs seems mandatory in RA patients especially when ANA is positive. RA cases with positive Anti-Jo-1 may develop anti synthetase syndrome and ILD.

Exogenous miRNA: A Perspective Role as Therapeutic in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune and chronic inflammatory disease that causes joint deformation. Till now several studies has been carried out promising its cure, but curing has not yet achieved to the satisfactory levels. Herbal approach to treat disease by a cross-kingdom mechanism via exogenous miRNA is an emerging trend to target associated genes with RA pathogenesis as a therapeutic potential. The concept of acquired/exogenous miRNA into pathophysiological prospect provides an opportunity to explore inter-species kingdom like regulation of plant miRNAs on human health. The change in gene expression was attributed by a short 22-24 nucleotide long sequence that binds to its complementary region to suppress/silence the gene expression. This makes exogenous miRNA a novel approach for targeted therapy to treat complex chronic inflammatory diseases. Here, aim of the review was to address significance of plant derived miRNA based targeted therapy to regulate inflammation in RA.

Differential Metabolome in Rheumatoid Arthritis: a Brief Perspective

PURPOSE OF REVIEW

Rheumatoid arthritis (RA) is a chronic autoimmune, inflammatory disease of the synovium that affects the movable joints. It develops due to the infiltration and invasion of the synovial joints by immune cells. Metabolism is anabolic or catabolic chemical reactions occurring in a cell. The biochemical pathways in synovial and immune cells are altered affecting the downstream metabolite formation. Changes in the metabolite levels alter signaling cascades which further intensify the disease. Despite current knowledge of metabolomics, there remain certain features that need to be elucidated to correlate the differential metabolite levels with RA.

RECENT FINDINGS

Metabolite profiling can be used to find altered patterns of metabolites in RA. Glucose, lipid, amino acid, and estrogen metabolism are the key pathways that are altered and contribute to the aggravation of RA. The altered metabolic pathways involved in different cells in RA results in complex interactions between metabolites and biomacromolecules; thus, it generates autoantigens. Moreover, understanding the correlation between differential metabolites and disease severity might help reveal potential new biomarkers and therapeutic targets for RA pathogenesis. So, considering the multi-faceted role of altered metabolites in the pathogenesis of RA, metabolic pathways of different cells are needed to be studied for a better understanding of their functions in the disease and thus, improving the present therapeutic strategies.

Chromatin accessibility landscapes of immune cells in rheumatoid arthritis nominate monocytes in disease pathogenesis

BACKGROUND

Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disease that involves a variety of cell types. However, how the epigenetic dysregulations of peripheral immune cells contribute to the pathogenesis of RA still remains largely unclear.

RESULTS

Here, we analysed the genome-wide active DNA regulatory elements of four major immune cells, namely monocytes, B cells, CD4⁺ T cells and CD8⁺ T cells, in peripheral blood of RA patients, osteoarthritis (OA) patients and healthy donors using Assay of Transposase Accessible Chromatin with sequencing (ATAC-seq). We found a strong RA-associated chromatin dysregulation signature in monocytes, but no other examined cell types. Moreover, we found that serum C-reactive protein (CRP) can induce the RA-associated chromatin dysregulation in monocytes via in vitro experiments. And the extent of this dysregulation was regulated through the transcription factor FRA2.

CONCLUSIONS

Together, our study revealed a CRP-induced pathogenic chromatin dysregulation signature in monocytes from RA patients and predicted the responsible signalling pathway as potential therapeutic targets for the disease.

Protocatechuic acid inhibits proliferation, migration and inflammatory response in rheumatoid arthritis fibroblast-like synoviocytes

Rheumatoid arthritis (RA) is a chronic joint inflammatory disease that is closely associated with dysregulation of fibroblast-like synoviocytes (FLSs). Protocatechuic acid (PCA), a phenolic compound of anthocyanins, has been proven to possess anti-inflammatory activity. However, the role of PCA in RA has not been investigated. In the present study, we aimed to explore the effects of PCA on the RA-FLSs. The results showed that PCA suppressed the proliferation, invasion, and migration of RA-FLSs in a dose-dependent manner. PCA treatment also inhibited the expressions of matrix metalloproteinase (MMP)-3 and MMP-13, as well as the secretion of inflammatory cytokines including TNF-α, IL-1β, IL-6 in RA-FLSs. Moreover, cell apoptosis of RA-FLSs was significantly induced by PCA treatment. PCA was found to repress the activation of NF-κB signalling, which was evidenced by the decreased expression of p-p65 and increased expression of IκBα. Furthermore, PCA significantly decreased the phosphorylation levels of Akt and mTOR in RA-FLSs. In conclusion, the results indicated that PCA exhibited an inhibitory effect on RA-FLSs via inhibiting the NF-κB and Akt/mTOR signalling pathways. These findings supported the concept that PCA might be a therapeutic agent for RA treatment.

Association Between the Extent of Periodontal Inflammation and the Severity of Rheumatoid Arthritis in Japanese Patients With Rheumatoid Arthritis

Objective

Periodontal inflammation can affect the progression of rheumatoid arthritis (RA), and RA drugs may influence the periodontal condition of patients with RA. We examined whether the association between periodontal inflammation and the severity of RA is influenced by RA medication.

Methods

This cross-sectional study recruited 98 Japanese patients with RA from an orthopaedic clinic. We assessed the severity of RA using the Steinbrocker class and stage. The periodontal inflamed surface area (PISA) was used as an indicator of periodontal status. We obtained data on RA medications from medical records. We examined the associations among periodontal tissue inflammation, RA medications, and RA severity using multinomial logistic regression analyses.

Results

In univariate multinomial logistic regression analyses, no significant association between PISA score and RA severity was observed. There was no significant association between PISA score and RA severity in multivariate analyses not including variables about RA drugs as independent variables. However, in multivariate analyses adjusted for RA drugs and other confounding variables, patients with a PISA >550 mm² had significantly higher odds ratios (ORs) for Steinbrocker class III-IV and stage III-IV (OR, 20.24; 95% confidence interval [CI], 1.78-229.85 and OR, 12.42; 95% CI, 1.79-86.49, respectively) compared to patients with PISA score ≤550 mm².

Conclusion

The extent of periodontal inflammation is associated with the severity of RA independent of RA medications.