Tumor necrosis factor α induces sustained signaling and a prolonged and unremitting inflammatory response in rheumatoid arthritis synovial fibroblasts

TroTNFα, a teleost tumour necrosis factor of golden pompano (Trachinotus ovatus), enhances pathogen clearance and acts as an immune adjuvant

Tumour necrosis factor (TNF) is one of the most pivotal factors of the TNF family and plays an essential biological role in immunity. However, the antibacterial function and mechanism of TNFα in teleosts are relatively poorly understood. In this study, a novel TNFα from Trachinotus ovatus (TroTNFα) was characterized. TroTNFα is widely expressed in immune tissues and increased after Vibrio harveyi infection. The recombinant protein TroTNFα facilitated the proliferation and chemotaxis of T. ovatus head kidney lymphocytes, induced apoptosis in human hepatocellular carcinoma cells (HepG2), and enhanced NF-κB promoter activity, whereas mutants with altered conserved receptor binding sites (Phe and Tyr mutated to Ala) lost these functions. Similarly, in vivo research revealed that, compared with the control, TroTNFα overexpression significantly reduced bacterial colonization, whereas the bacterial colonization of the mutants was similar to that of the control. Furthermore, our results showed that TroTNFα increased the vaccine-induced immune responses induced by the DNA vaccine pCTssJ against V. harveyi. Taken together, our results indicate that TroTNFα plays an indispensable role in antibacterial immunity, providing the first evidence that the binding sites (Phe144 and Tyr216) of TroTNFα are crucial in these processes in teleosts and enhances DNA vaccine efficacy as an immune adjuvant.

The Spectrum of Papillophlebitis

PURPOSE

Papillophlebitis is a rare condition, manifesting as CRVO in the young adults. We aim to present our experience in managing patients with papillophlebitis.

METHODS

Retrospective review of patients' medical files.

RESULTS

Included were seven patients with a mean presenting age of 24.86 ± 4.4 years and mean follow-up of 40.4 ± 50.5 months. No pre-existing systemic illness was reported by any patient. One patient was subsequently diagnosed to have Behçet disease and another patient was diagnosed with homozygous mutation to MTHFR C6771. On presentation, fluorescein angiograms showed diffuse vascular and optic disc leakage. Four patients presented with papillophlebitis-associated CME, for which they were treated with systemic steroids and intravitreal anti-VEGF injections. One patient showed full recovery. In 3 patients, due to the protracted course of papillophlebitis and refractory CME, adalimumab was added. All 3 patients eventually showed complete resolution of CME. Two of them eventually developed extensive peripheral capillary non-perfusion that was treated with panretinal photocoagulation. Three patients did not develop CME: In two patients, papillophlebitis resolved after a short course of prednisone while in the third patient, papillophlebitis resolved spontaneously. Mean ± SD presenting log MAR VA was 0.2 ± 0.32 and it was 0.057 ± 0.11 at the last follow-up.

CONCLUSION

To the best of our knowledge, this is the first description that suggests a role for TNF-ɑ blockers in the management of patients with recalcitrant papillophlebitis and non-responsive CME. Further studies are needed in order to thoroughly investigate the molecular background of papillophlebitis and clinical outcomes associated with this class of medications.

NF-κB Signaling Pathway in Rheumatoid Arthritis: Mechanisms and Therapeutic Potential

Rheumatoid arthritis (RA) is an autoimmune chronic inflammatory disease that imposes a heavy economic burden on patients and society. Bone and cartilage destruction is considered an important factor leading to RA, and inflammation, oxidative stress, and mitochondrial dysfunction are closely related to bone erosion and cartilage destruction in RA. Currently, there are limitations in the clinical treatment methods for RA, which urgently necessitates finding new effective treatments for patients. Nuclear transcription factor-κB (NF-κB) is a signaling transcription factor that is widely present in various cells. It plays an important role as a stress source in the cellular environment and regulates gene expression in processes such as immunity, inflammation, cell proliferation, and apoptosis. NF-κB has long been recognized as a pathogenic factor of RA, and its activation can exacerbate RA by promoting inflammation, oxidative stress, mitochondrial dysfunction, and bone destruction. Conversely, inhibiting the activity of the NF-κB pathway effectively inhibits these pathological processes, thereby alleviating RA. Therefore, NF-κB may be a potential therapeutic target for RA. This article describes the physiological structure of NF-κB and its important role in RA through the regulation of oxidative stress, inflammatory response, mitochondrial function, and bone destruction. Meanwhile, we also summarized the impact of NF-κB crosstalk with other signaling pathways on RA and the effect of related drugs or inhibitors targeting NF-κB on RA. The purpose of this article is to provide evidence for the role of NF-κB in RA and to emphasize its significant role in RA by elucidating the mechanisms, so as to provide a theoretical basis for targeting the NF-κB pathway as a treatment for RA.

Humoral factors in serum as predictors of therapeutic response to tumor necrosis factor inhibitors in rheumatoid arthritis

AIM

This study aimed to evaluate the predictive value of serum humoral factors in determining the therapeutic responses to biologic DMARDs (bDMARDs), especially TNF inhibitors (TNFis), in patients with RA.

METHODS

A cohort of 52 patients with RA who were treated with bDMARDs, including TNFis, abatacept, and tocilizumab, was analyzed. Serum samples were collected at baseline (t1), 5 ± 1 (t2), and 14 ± 2 weeks (t3) after treatment. A bead-based immunoassay was used to quantify serum cytokines/chemokines. Treatment response was determined 1 year after initiation.

RESULTS

Distinct patterns of IL-6 behaviors were observed among different bDMARDs. Patients exhibiting IL-6 rebound at 14 weeks were more likely to be non-responders to TNFi after 1 year, and this rebound appeared to be associated with increases in IFN-γ and IL-12 levels. IFN-β was more detectable than IFN-α2 in RA. Additionally, patients with measurable IFN-β at baseline tended to be TNFi responders.

CONCLUSION

Monitoring serum humoral factors may offer valuable insights into the likelihood of therapeutic success of TNFi in patients with RA. IL-6 rebound at 14 weeks might serve as an early indicator of non-responsiveness to TNFi. These findings highlight the potential of personalized treatment strategies for RA based on serum humoral factor profiling. Larger prospective studies are needed to validate these results and elucidate the underlying mechanisms.

The reactive stroma response regulates the immune landscape in prostate cancer

Prostate cancer remains the most commonly diagnosed and the second leading cause of cancer-related deaths in men in the United States. The neoplastic transformation of prostate epithelia, concomitant with modulations in the stromal compartment, known as reactive stromal response, is critical for the growth, development, and progression of prostate cancer. Reactive stroma typifies an emergent response to disrupted tissue homeostasis commonly observed in wound repair and pathological conditions such as cancer. Despite the significance of reactive stroma in prostate cancer pathobiology, our understanding of the ontogeny, phenotypic and functional heterogeneity, and reactive stromal regulation of the immune microenvironment in prostate cancer remains limited. Traditionally characterized to have an immunologically "cold" tumor microenvironment, prostate cancer presents significant challenges for advancing immunotherapy compared to other solid tumors. This review explores the detrimental role of reactive stroma in prostate cancer, particularly its immunomodulatory function. Understanding the molecular characteristics and dynamic transcriptional program of the reactive stromal populations in tandem with tumor progression could offer insights into enhancing immunotherapy efficacy against prostate cancer.

Synovial fibroblasts from children with oligoarticular juvenile idiopathic arthritis induce migration and prolong viability of neutrophils

Introduction

Little is known of the processes that trigger neutrophil activation in the joint of patients with oligoarticular juvenile idiopathic arthritis (oJIA), and if synovial fibroblasts (S-Fib) play an important role in the activation. Therefore, we aimed to investigate whether S-Fib derived from oJIA patients drive neutrophil activation.

Methods

Synovial fluid (SF) was collected from patients with oJIA. S-Fib were isolated from the SF of n = 7 patients through passaging. Subsequently, the S-Fib were primed or not with 20% of pooled SF. Supernatants were used to study migration of neutrophils in a transwell system. Additionally, the influence of S-Fib on neutrophils were studied in co-cultures. Phenotype and viability were assessed by flow cytometry. Neutrophil function was tested through the production of reactive oxygen species (ROS), and supernatants were tested for myeloperoxidase (MPO) release and elastase activity.

Results

Supernatants of S-Fib induced neutrophil migration (n = 5, p = 0.0491), which was further pronounced using supernatants from SF-primed S-Fib (p = 0.0063). Additionally, co-culture between SF-primed S-Fib and neutrophils resulted in prolonged viability (n = 5, p = 0.0094), with little effect on activation markers, e.g., CD11b. Conversely, co-culture did not induce functional alterations (n = 4), such as production of ROS (p > 0.1570), release of MPO (p > 0.4934) or elastase activity (p > 0.0904). Finally, supernatant stimulation did not replicate the results of prolonged viability (p = 0.9102), suggesting a role of cell-contact.

Conclusion

S-Fib from patients with oJIA induce migration of neutrophils via soluble mediators and, in addition, S-Fib prolong neutrophil viability in a cell-contact dependent manner. These mechanisms could be important for accumulation of neutrophils during arthritis.

Targeting TNF-α-induced expression of TTR and RAGE in rheumatoid arthritis: Apigenin's mediated therapeutic approach

BACKGROUND

Rheumatoid arthritis (RA) is a chronic inflammatory disease induced by TNF-α, which increases fibroblast-like synoviocytes inflammation, resulting in cartilage destruction. The current work sought to comprehend the pathophysiological importance of TNF-α stimulation on differential protein expression and their regulation by apigenin using in-vitro and in-vivo models of RA.

METHODS

The human RA synovial fibroblast cells were stimulated with or without TNF-α (10 ng/ml) and treated with 40 μM apigenin. In-silico, in-vitro and in-vivo studies were performed to confirm the pathophysiological significance of apigenin on pro-inflammatory cytokines and on differential expression of TTR and RAGE proteins.

RESULTS

TNF-α induced inflammatory response in synoviocytes revealed higher levels of IL-6, IL-1β, and TNF-α cytokines and upregulated differential expression of TTR and RAGE. In-silico results demonstrated that apigenin has a binding affinity towards TNF-α, indicating its potential effect in the inflammatory process. Both in-vitro and in-vivo results obtained by Western Blot analysis suggested that apigenin reduced the level of p65 (p = 0.005), TTR (p = 0.002), and RAGE (p = 0.020).

CONCLUSION

The findings of this study suggested that TNF-α promotes the differential expression of pro-inflammatory cytokines, TTR, and RAGE via NF-kB pathways activation. Anti-inflammatory effect of apigenin impedes TNF-α mediated dysregulation or expression associated with RA pathogenesis.

Gut Subdoligranulum variabile ameliorates rheumatoid arthritis by promoting TSG-6 synthesis from joint cells

Background

A burgeoning body of evidence has substantiated the association between alterations in the composition of the gut microbiota and rheumatoid arthritis (RA). Nevertheless, our understanding of the intricate mechanisms underpinning this association is limited.

Methods

To investigate whether the gut microbiota influences the pathogenesis of RA through metabolism or immunity, we performed rigorous synthesis analyses using aggregated statistics from published genome-wide association studies (GWAS) using two-sample Mendelian randomization (MR) and mediated MR techniques, including two-step MR and multivariate MR analyses. Subsequently, we conducted in vitro cellular validation of the analyzed Microbial-Cytokine-RA pathway. We determined the optimal culture conditions through co-culture experiments involving concentration and time. Cell Counting Kit-8 (CCK-8) assays were employed to assess cellular viability, and enzyme-linked immunosorbent assays (ELISA) were performed to assess tumor necrosis factor-inducible gene 6 protein (TSG-6) and tumor necrosis factor-α (TNF-α) levels.

Results

Our univariable MR results confirmed 15 microbial traits, 7 metabolites and 2 cytokines that may be causally associated with RA (P FDR < 0.05). Mediation analysis revealed that microbial traits influence the risk of RA through metabolite or cytokine (proportion mediated: 7.75% - 58.22%). In vitro experiments demonstrated that TSG-6 was highly expressed in the Subdoligranulum variabile treatment group and was correlated with decreased RA severity (reduced TNF-α expression). Silencing the TSG-6 gene significantly increased TNF-α expression, regardless of treatment with S. variabile. Additionally, S. variabile-secreted exosomes exhibited the same effect.

Conclusion

The results of this study suggest that S. variabile has the potential to promote TSG-6 secretion, thereby reducing RA inflammation.

Study of the mechanism underlying the anti-inflammatory effect of Miao medicine comprising raw and processed Radix Wikstroemia indica using the "sweat soaking method"

ETHNOPHARMACOLOGICAL RELEVANCE

To explore the differences in the anti-inflammatory efficacy and mechanisms of the Miao medicine, both raw and after processing, using the "sweat soaking method" of Radix Wikstroemia indica (RWI).

AIM OF THE STUDY

The purpose of this study was to explore the differences in the anti-inflammatory efficacy and mechanism of action before and after the processing of the Miao medicine (RWI) using the "sweat soaking method."

MATERIALS AND METHODS

Network pharmacology technology was used to construct the "drug-component target-pathway-disease" network, and the main anti-inflammatory pathways of RWI were identified. Rat models of collagen-induced arthritis were established. The changes in body weight, swelling rate of the foot pad and ankle joint, arthritis index, thymus index, spleen index, pathological changes of the ankle joint, and the content of inflammatory cytokines (IL-1β, IL-2, IL-6, IL-10, TNF-α, and NO) were used as indices to evaluate the effect of RWI on rats with collagen-induced arthritis before and after its processing. Plasma and urine samples were collected from the rats, and the potential biomarkers of, and metabolic pathways underlying the anti-inflammatory effects of RWI before and after processing were identified using 1H-Nuclear magnetic resonance metabolomics combined with a multivariate statistical analysis.

RESULTS

Eleven key anti-inflammatory targets of IL6, IL-1β, TNF, ALB, AKT1, IFNG, INS, STAT3, EGFR, TP53, and SRC were identified by network pharmacology. The PI3K-Akt signaling pathway, steroid hormone biosynthesis, arginine biosynthesis, arginine and proline metabolism, tryptophan metabolism, and other pathways were mainly involved in these effects. Pharmacodynamic studies found that both raw and processed RWI products downregulated inflammatory factors in rats with collagen-induced arthritis and alleviated the pathological changes. A total of 41 potential pathways for the anti-inflammatory effects of raw RWI products and 36 potential pathways for the anti-inflammatory effects of processed RWI products were identified by plasma and urine metabolomics. The common pathways of network pharmacology and metabolomics were steroid hormone biosynthesis, arginine biosynthesis, arginine and proline metabolism, and tryptophan metabolism.

CONCLUSIONS

The anti-inflammatory effect of RWI was mainly related to the regulation of steroid hormone biosynthesis, arginine biosynthesis, arginine and proline metabolism, and tryptophan metabolism. Finally, the "sweat soaking method" enhanced the anti-inflammatory effect of RWI.

Patterns and determinants of response to novel therapies in juvenile and adult-onset polyarthritis

Biologic and targeted synthetic DMARDs (b/tsDMARDs) have revolutionized the management of multiple rheumatic inflammatory conditions. Among these, polyarticular JIA (pJIA) and RA display similarities in terms of disease pathophysiology and response pattern to b/tsDMARDs. Indeed, the therapeutic efficacy of novel targeted drugs is variable among individual patients, in both RA and pJIA. The mechanisms and determinants of this heterogeneous response are diverse and complex, such that the development of true 'precision'-medicine strategies has proven highly challenging. In this review, we will discuss pathophysiological, patient-specific, drug-specific and environmental factors contributing to individual therapeutic response in pJIA in comparison with what is known in RA. Although some biomarkers have been identified that stratify with respect to the likelihood of either therapeutic response or non-response, few have proved useful in clinical practice so far, likely due to the complexity of treatment-response mechanisms. Consequently, we propose a pragmatic, patient-centred and clinically based approach, i.e. personalized instead of biomarker-based precision medicine in JIA.

Neointimal myofibroblasts contribute to maintaining Th1/Tc1 and Th17/Tc17 inflammation in giant cell arteritis

Vascular smooth muscle cells (VSMCs) have been shown to play a role in the pathogenesis of giant cell arteritis (GCA) through their capacity to produce chemokines recruiting T cells and monocytes in the arterial wall and their ability to migrate and proliferate in the neointima where they acquire a myofibroblast (MF) phenotype, leading to vascular stenosis. This study aimed to investigate if MFs could also impact T-cell polarization. Confocal microscopy was used to analyze fresh fragments of temporal artery biopsies (TABs). Healthy TAB sections were cultured to obtain MFs, which were then treated or not with interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α) and analyzed by immunofluorescence and RT-PCR. After peripheral blood mononuclear cells and MFs were co-cultured for seven days, T-cell polarization was analyzed by flow cytometry. In the neointima of GCA arteries, we observed a phenotypic heterogeneity among VSMCs that was consistent with a MF phenotype (α-SMA+CD90+desmin+MYH11+) with a high level of STAT1 phosphorylation. Co-culture experiments showed that MFs sustain Th1/Tc1 and Th17/Tc17 polarizations. The increased Th1 and Tc1 polarization was further enhanced following the stimulation of MFs with IFN-γ and TNF-α, which induced STAT1 phosphorylation in MFs. These findings correlated with increases in the production of IL-1β, IL-6, IL-12 and IL-23 by MFs. Our study showed that MFs play an additional role in the pathogenesis of GCA through their ability to maintain Th17/Tc17 and Th1/Tc1 polarizations, the latter being further enhanced in case of stimulation of MF with IFN-γ and TNF-α.

Network Pharmacology Combined with Molecular Docking Approach to Investigate the Mechanism of ChuShiWeiLing Decoction against Perianal Eczema

BACKGROUND

ChuShiWeiLing Decoction (CSWLD) is a famous classical Chinese prescription for the treatment of eczema with desirable effect in clinical practice. It has gradually exerted good curative effects on perianal eczema (PE) in recent years, but its specific mechanism is not elucidated yet.

OBJECTIVE

This research explores the underlying pharmacological mechanism of CSWLD in addressing PE through network pharmacology combined with molecular docking strategy.

METHODS

The key chemical compounds and potential target genes of CSWLD were screened by bioinformatics. The major targets of CSWLD were discovered using network modules. Functional annotation of Gene Ontology (GO) was undertaken, as well as pathway enrichment analysis using the Kyoto Encyclopedia of Genes and Genomes (KEGG). Molecular docking of core protein-ligand interactions was modeled using AutoDock software. Pymol software was used to perform a molecular dynamics simulation for the ideal core protein-ligand that was discovered by molecular docking.

RESULTS

A total of 2,853 active compounds and 922 targets of CSWLD were collected. The target with a higher degree was identified through the PPI network, namely TNF, IL6, ALB, STAT3, EGFR, TLR4, CXCL8 and PTPRC. GO and KEGG analyses suggested that CSWLD treatment of PE mainly involves cellular activation, activation of leukocytes, and adhesion among leukocytes. The molecular docking results showed that wogonin, hederagenin and quercetin of CSWLD could bind to IL-6 and TNF, respectively.

CONCLUSION

Our results indicated that the bioactives, potential targets, and molecular mechanism of CSWLD against PE.

Research progress in arthritis treatment with the active components of Herba siegesbeckiae

Arthritis is a group of diseases characterized by joint pain, swelling, stiffness, and limited movement. Osteoarthritis, rheumatoid arthritis, and gouty arthritis are the most common types of arthritis. Arthritis severely affects the quality of life of patients and imposes a heavy financial and medical burden on their families and society at large. As a widely used traditional Chinese medicine, Herba siegesbeckiae has many pharmacological effects such as anti-inflammatory and analgesic, anti-ischemic injury, cardiovascular protection, and hypoglycemic. In addition, it has significant therapeutic effects on arthritis. The rich chemical compositions of H. siegesbeckiae primarily include diterpenoids, sesquiterpenoids, and flavonoids. As one of the main active components of H. siegesbeckiae, kirenol and quercetin play a vital role in reducing arthritis symptoms. In the present study, the research progress in arthritis treatment with the active components of H. siegesbeckiae is reviewed.

Prolactin Inhibits or Stimulates the Inflammatory Response of Joint Tissues in a Cytokine-dependent Manner

The close association between rheumatoid arthritis (RA), sex, reproductive state, and stress has long linked prolactin (PRL) to disease progression. PRL has both proinflammatory and anti-inflammatory outcomes in RA, but responsible mechanisms are not understood. Here, we show that PRL modifies in an opposite manner the proinflammatory actions of IL-1β and TNF-α in mouse synovial fibroblasts in culture. Both IL-1β and TNF-α upregulated the metabolic activity and the expression of proinflammatory factors (Il1b, Inos, and Il6) via the activation of the nuclear factor-κB (NF-κB) signaling pathway. However, IL-1β increased and TNF-α decreased the levels of the long PRL receptor isoform in association with dual actions of PRL on synovial fibroblast inflammatory response. PRL reduced the proinflammatory effect and activation of NF-κB by IL-1β but increased TNF-α-induced inflammation and NF-κB signaling. The double-faceted role of PRL against the 2 cytokines manifested also in vivo. IL-1β or TNF-α with or without PRL were injected into the knee joints of healthy mice, and joint inflammation was monitored after 24 hours. IL-1β and TNF-α increased the joint expression of proinflammatory factors and the infiltration of immune cells. PRL prevented the actions of IL-1β but was either inactive or further increased the proinflammatory effect of TNF-α. We conclude that PRL exerts opposite actions on joint inflammation in males and females that depend on specific proinflammatory cytokines, the level of the PRL receptor, and the activation of NF-κB signaling. Dual actions of PRL may help balance joint inflammation in RA and provide insights for development of new treatments.

A novel drug combination of Tofacitinib and Iguratimod alleviates rheumatoid arthritis and secondary osteoporosis

BACKGROUND

The inadequate response of some patients with rheumatoid arthritis (RA) to current therapies is an issue that needs to be addressed. Patients with refractory RA (RRA) are often accompanied by high Tumor necrosis factor (TNF) expression. We evaluated the synergistic therapeutic effects of the combination of Iguratimod (IGU) and Tofacitinib (TOF) on RRA and secondary osteoporosis.

METHODS

Pathological changes in the ankle joints of collagen-induced arthritis (CIA) + TNF model rats were assessed using hematoxylin and eosin (HE) staining. Immunohistochemistry (IHC) and immunofluorescence (IF) were used to evaluate pyroptosis-related protein levels in the synovial tissues. Moreover, the knee joint was investigated by performing HE staining, IHC, and micro-computed tomography. Furthermore, in vitro, western blotting and enzyme-linked immunosorbent assay (ELISA) were performed to detect the effects of TOF and IGU on TNF-α-induced pyroptosis in fibroblast-like synoviocytes of RA.

RESULTS

After treatment with TOF and/or IGU, the arthritis scores, inflammatory cell infiltration in synovial tissues, and levels of interleukin (IL)-18, IL-1β, and IL-6 in the plasma were remarkably increased in the CIA + TNF model and dramatically decreased in the combination group. The expression of pyroptosis-related proteins was significantly lower in the combination group than in the CIA + TNF group, and a consistent trend was observed in vitro. Bone destruction was significantly alleviated, and the bone turnover rate was remarkably increased in the combination group compared to that in the CIA + TNF model.

CONCLUSION

TOF + IGU alleviated the severity of RRA in the CIA + TNF rat model, relieving joint inflammation, reducing bone erosion, and suppressing pyroptosis. The combined application of TOF and IGU may have a superimposed therapeutic effect on RRA and secondary osteoporotic bone remodeling.

Investigation of altered retinal microvasculature in female patients with rheumatoid arthritis: optical coherence tomography angiography detection

BACKGROUND

Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disorder that primarily causes symmetrical polyarthritis and bone deformity. In RA patients, sight-threatening inflammatory eye complications would be expected.

OBJECTIVE

The objective of the study is to ascertain the macular retinal vessel density changes in RA patients and controls using optical coherence tomography angiography (OCTA), and to investigate the association between disease and microvascular density alterations.

METHODS

A total of 12 RA patients (24 eyes) and 12 age- and gender-matched control participants (24 eyes) were recruited to the study. We used the Early Treatment Diabetic Retinopathy Study partitioning, hemispheric quadrants and annular partitioning to segment each image into different subregions. The vascular density of superficial retina layer, deep retina layer and conjunctival capillary plexus was quantitatively measured by OCTA and compared with the control group. Correlation analysis was used to explore the relationship between STMI and conjunctival capillaries densities.

RESULTS

In the superficial retinal layer, the vascular density of S, I, L, SL, SR, IL and C1-C5 were significantly decreased in the RA group compared with the control group (P<0.05). For the deep retinal layer, the vascular density of S, SL, SR, IL, C1, C2 and C4 also decreased in RA group. A significant positive correlation was indicated between conjunctival vascular and STMI densities (r = 0.713, P<0.05).

CONCLUSION

OCTA results suggest that RA patients present with a reduced macular retinal vascular density. These subtle alterations of ocular microcirculation may precede severe eye involvements and may be a potential biomarker for early distinguishing abnormal eyes from healthy eyes.

Innate immune memory in inflammatory arthritis

The concept of immunological memory was demonstrated in antiquity when protection against re-exposure to pathogens was observed during the plague of Athens. Immunological memory has been linked with the adaptive features of T and B cells; however, in the past decade, evidence has demonstrated that innate immune cells can exhibit memory, a phenomenon called 'innate immune memory' or 'trained immunity'. Innate immune memory is currently being defined and is transforming our understanding of chronic inflammation and autoimmunity. In this Review, we provide an up-to-date overview of the memory-like features of innate immune cells in inflammatory arthritis and the crosstalk between chronic inflammatory milieu and cell reprogramming. Aberrant pro-inflammatory signalling, including cytokines, regulates the metabolic and epigenetic reprogramming of haematopoietic progenitors, leading to exacerbated inflammatory responses and osteoclast differentiation, in turn leading to bone destruction. Moreover, imprinted memory on mature cells including terminally differentiated osteoclasts alters responsiveness to therapies and modifies disease outcomes, commonly manifested by persistent inflammatory flares and relapse following medication withdrawal.

Tibetan medicine Qi-Sai-Er-Sang-Dang-Song Decoction inhibits TNF-α-induced rheumatoid arthritis in human fibroblast-like synoviocytes via regulating NOTCH1/NF-κB/NLRP3 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Qi-Sai-Er-Sang-Dang-Song Decoction (QSD, ཆུ་སེར་སེང་ལྡེང་སུམ་ཐང་།), a Tibetan classical herbal formula, is commonly used in Tibetan hospital preparation for the treatment of rheumatoid arthritis (RA). Its efficacy is to relieve inflammation, dispel cold, remove dampness, and alleviate pain. However, its anti-RA mechanism is still unclear.

AIM OF THE STUDY

This study aimed to investigate the effect of QSD on rheumatoid arthritis and explore its anti-inflammatory mechanism against human fibroblast-like synoviocytes (HFLSs) by regulating the notch family of receptors (NOTCH1)/Nuclear factor-κB (NF-κB)/nucleotide-binding (NLRP3) pathway.

MATERIALS AND METHODS

We used ultra-performance liquid chromatography coupled with Q-TOF mass spectrometry (UPLC-Q-TOF-MS) to identify the chemical composition of QSD. Then, HFLSs were exposed to drug-containing serum. The effect of QSD drug-containing serum on HFLS viability was detected using the cell counting kit-8 (CCK-8) assay. Next, we explored the anti-inflammatory effect of QSD using enzyme-linked immunosorbent assay (ELISA) for inflammatory factors, such as interleukin-18 (IL-18), interleukin-1β (IL-1β), and interleukin-6 (IL-6). The expression of NOTCH-related proteins, a member of the NOTCH1, Cleaved NOTCH1, hairy and enhancer of split-1 (HES-1), NF-κB p65, NF-κB pp65, NLRP3, and delta-like 1 (DLL-1), was examined using western blotting. Furthermore, the relative mRNA expression levels of NOTCH1, NF-κB p65, NLRP3, DLL-1, and HES-1 were detected using real-time quantitative (RT-qPCR). To explore the mechanism underlying the anti-RA effect of QSD, we the used the NOTCH signaling pathway inhibitor LY411575 and transfection with a NOTCH1 siRNA. In addition, we employed immunofluorescence to determine the expression of HES-1 and NF-κB p65 in vitro.

RESULT

Our results revealed that QSD ameliorated inflammation in HFLSs. Compared with the model group, the QSD drug-containing serum group had obviously down-regulated levels of IL-18, IL-1β, and IL-6. Consistently, the CCK-8 results showed that the QSD drug-containing serum had no obvious toxicity towards HFLSs. Moreover, both LY411575 and siNOTCH1, QSD could reduce NOTCH1, NLRP3, and HES-1 protein expression levels, and LY411575 could significantly inhibit the expression levels of NF-κB p65, NF-κB pp65, and Cleaved NOTCH1 (p < 0.05). siNOTCH1 could also suppress the expression of DLL-1. The RT-qPCR results indicated that QSD could downregulate the relative mRNA expression levels of NOTCH1, NF-κB p65, NLRP3, DLL-1, and HES-1 in HFLSs (p < 0.05). In the immunofluorescence experiment, the fluorescence intensities of HES-1 and NF-κB p65 in HFLSs were found to decrease after exposure to QSD drug-containing serum (p < 0.05). Ultimately, 44 chemical components were detected in QSD using UPLC-Q-TOF-MS.

CONCLUSION

This study reveals that the QSD can markedly ameliorate inflammation induced by TNF-α on HFLS. The effect of QSD on HFLS may be exerted by inhibition of the NOTCH1/NF-κB/NLRP3 signaling pathway.

Molecular characterization, expression analysis and function identification of TNFα in black rockfish (Sebastes schlegelii)

TNFα, as a pro-inflammatory cytokine, plays an important role in inflammation and immune homeostasis maintaining. However, the knowledge about the immune functions of teleost TNFα against bacterial infections is still limited. In this study, the TNFα was characterized from black rockfish (Sebastes schlegelii). The bioinformatics analyses showed the evolutionary conservations in sequence and structure. The expression levels of Ss_TNFα mRNA were significantly up-regulated in the spleen and intestine after Aeromonas salmonicides and Edwardsiella tarda infections, and dramatically down-regulated in PBLs after LPS and poly I:C stimulations. Meanwhile, the extremely up-regulated expressions of other inflammatory cytokines (especially for IL-1β and IL17C) were observed in the intestine and spleen after bacterial infection and down-regulations were obtained in PBLs. The significant regulation with expression patterns of Ss_TNFα and other inflammatory cytokine mRNAs illustrated the variations of immunity in different tissues and cells of black rockfish. The regulated functions of Ss_TNFα in the up/downstream signaling pathways were preliminarily verified on the transcription and translation levels. Subsequently, in vitro knockdown of Ss_TNFα in the intestine cells of black rockfish confirmed the important immune roles of Ss_TNFα. Finally, the apoptotic analyses were conducted in PBLs and intestine cells of black rockfish. The rapid increases of the apoptotic rates were obtained in both PBLs and intestine cells after treatment with rSs_TNFα, but distinct apoptotic rates at the early and late stages of apoptosis were observed between these two types of cells. The results of apoptotic analyses suggested that Ss_TNFα could trigger apoptosis of different cells in different strategies in black rockfish. Overall, the findings in this study indicated the important roles of Ss_TNFα in the immune system of black rockfish during pathogenic infection, as well as the potential function on biomarker for monitoring the health status.

Galectin-3 interacts with PD-1 and counteracts the PD-1 pathway-driven regulation of T cell and osteoclast activity in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by joint inflammation and bone erosions. The glycosylated programmed death-1 (PD-1) receptor plays an important role in regulating immune responses and maintaining tolerance. In this study, we focus on two features observed in RA: impaired PD-1 signalling and Galectin-3 (Gal-3) upregulation. We hypothesize that Gal-3 binds PD-1 and PD-1 ligands, potentially contributing to impaired PD-1 signalling. PD-1 and Gal-3 levels in RA synovial fluid (SF) and plasma were evaluated by ELISA. PD-1 and Gal-3 interaction was examined by Surface Plasmon Resonance and ELISA. PD-1, PD-L1 and Gal-3 expression on mononuclear cells from SF and peripheral blood as well as fibroblast-like synoviocytes were examined by flow cytometry. Effects of Gal-3 and PD-L1 on osteoclast formation was evaluated by tartrate-resistant acid phosphatase assay. We show that Gal-3 binds PD-1 and PD-L1. Results demonstrated high expression of PD-1 and Gal-3 on mononuclear cells, especially from SF. Gal-3 inhibited PD-1 signalling when PD-L1 was present. Furthermore, a role of Gal-3 in osteoclast formation was observed in vitro, both directly but also through PD-1:PD-L1 inhibition. Effects of Gal-3 on the PD-1 signalling axis are proposed to be inhibitory, meaning high Gal-3 levels in the complex synovial microenvironment are not desirable in RA. Preventing Gal-3's inhibitory role on PD-1 signalling could, therefore, be a therapeutic target in RA by affecting inflammatory T cell responses and osteoclasts.

The Effective Treatment of Purpurin on Inflammation and Adjuvant-Induced Arthritis

Rubia cordifolia L. (Rubiaceae), one of the traditional anti-rheumatic herbal medicines in China, has been used to treat rheumatoid arthritis (RA) since ancient times. Purpurin, an active compound of Rubia cordifolia L., has been identified in previous studies and exerts antibacterial, antigenotoxic, anticancer, and antioxidant effects. However, the efficacy and the underlying mechanism of purpurin to alleviate RA are unclear. In this study, the effect of purpurin on inflammation was investigated using macrophage RAW264.7 inflammatory cells, induced by lipopolysaccharide (LPS), and adjuvant-induced arthritis (AIA) rat was established to explore the effect of purpurin on joint damage and immune disorders; the network pharmacology and molecular docking were integrated to dig out the prospective target. Purpurin showed significantly anti-inflammatory effect by reducing the content of IL-6, TNF-α, and IL-1β and increasing IL-10. Besides, purpurin obviously improved joint injury and hypotoxicity in the liver and spleen and regulated the level of FOXP3 and CD4+/CD8+. Furthermore, purpurin reduced the MMP3 content of AIA rats. Network pharmacology and molecular docking also suggested that MMP3 may be the key target of purpurin against RA. The results of this study strongly indicated that purpurin has a potential effect on anti-RA.

Fibroblast heterogeneity: Keystone of tissue homeostasis and pathology in inflammation and ageing

Fibroblasts, derived from the embryonic mesenchyme, are a diverse array of cells with roles in development, homeostasis, repair, and disease across tissues. In doing so, fibroblasts maintain micro-environmental homeostasis and create tissue niches by producing a complex extracellular matrix (ECM) including various structural proteins. Although long considered phenotypically homogenous and functionally identical, the emergence of novel technologies such as single cell transcriptomics has allowed the identification of different phenotypic and cellular states to be attributed to fibroblasts, highlighting their role in tissue regulation and inflammation. Therefore, fibroblasts are now recognised as central actors in many diseases, increasing the need to discover new therapies targeting those cells. Herein, we review the phenotypic heterogeneity and functionality of these cells and their roles in health and disease.

Site of invasion revisited: epigenetic drivers of joint destruction in RA

New analytical methods and the increasing availability of synovial biopsies have recently provided unprecedented insights into synovial activation in general and synovial fibroblast (SF) biology in particular. In the course of this development, SFs have become one of the most rapidly evolving and exciting fields of rheumatoid arthritis (RA) research. While their active role in the invasion of RA synovium into cartilage has long been studied, recent studies have brought new aspects of their heterogeneity and propagation in RA. This review integrates old and new evidence to give an overview picture of the processes active at the sites of invasive synovial tissue growth in RA.

Metabolic reprogramming in Rheumatoid Arthritis Synovial Fibroblasts: A hybrid modeling approach

Rheumatoid Arthritis (RA) is an autoimmune disease characterized by a highly invasive pannus formation consisting mainly of Synovial Fibroblasts (RASFs). This pannus leads to cartilage, bone, and soft tissue destruction in the affected joint. RASFs' activation is associated with metabolic alterations resulting from dysregulation of extracellular signals' transduction and gene regulation. Deciphering the intricate mechanisms at the origin of this metabolic reprogramming may provide significant insight into RASFs' involvement in RA's pathogenesis and offer new therapeutic strategies. Qualitative and quantitative dynamic modeling can address some of these features, but hybrid models represent a real asset in their ability to span multiple layers of biological machinery. This work presents the first hybrid RASF model: the combination of a cell-specific qualitative regulatory network with a global metabolic network. The automated framework for hybrid modeling exploits the regulatory network's trap-spaces as additional constraints on the metabolic network. Subsequent flux balance analysis allows assessment of RASFs' regulatory outcomes' impact on their metabolic flux distribution. The hybrid RASF model reproduces the experimentally observed metabolic reprogramming induced by signaling and gene regulation in RASFs. Simulations also enable further hypotheses on the potential reverse Warburg effect in RA. RASFs may undergo metabolic reprogramming to turn into "metabolic factories", producing high levels of energy-rich fuels and nutrients for neighboring demanding cells through the crucial role of HIF1.

Effect of different types of immunosuppressive therapy on the parameters of TNF receptor expression in patients with rheumatoid arthritis

   Background. The balance of TNF receptor expression on immune cells is a key factor determining cytokine-induced activation of proapoptotic or proliferative signaling pathways. As a result, the changes in cytokine level and in expression of its receptors may be one of the mechanisms that regulate the level of systemic and local inflammation in rheumatoid arthritis (RA) and determine the degree of therapy effectiveness.   The aim. To study the effect of rheumatoid arthritis therapy on the change in the patterns of TNF receptors expression in terms of co-expression and the number of receptors on the main subpopulations of immunocompetent cells.Materials and methods. A comparative analysis of the profiles of TNF receptors type 1 and 2 (TNFR1/2) co-expression was carried out in patients with RA (n = 16) before and after having inpatient effective therapy and in comparison with a group of healthy individuals (n = 21). We compared the number of receptors and the proportion of cells expressing the corresponding receptor using flow cytometry and studied the subpopulations of regulatory T cells, T cells, B cells, and monocytes.   Results. In patients with RA, there is a significant redistribution of TNFR1 and TNFR2 expression on immunocompetent cells, while the intensity of changes is associated not only with disease severity indicators, but also with the therapy received. The key adaptive mechanism of the TNF system in long-term treatment refractory course of RA is a change in the proportion of double-positive TNFR1+TNFR2+ cells, while the effectiveness of therapy and clinical indicators of the disease severity are associated with individual variability in the parameters of type 2 receptors expression.   Conclusions. The data obtained confirm the existence of a relationship between an imbalance in the expression of type 1 and type 2 TNF receptors on immunocompetent cells and the effectiveness of response to therapy. The identified patterns of typical changes in TNFR1/2 co-expression in RA can be used as potential therapeutic targets and predictive factors for the effectiveness of therapy.

Targeting fibroblast-like synoviocytes in rheumatoid arthritis

Fibroblast-like synoviocytes (FLS) are mesenchymal-derived cells that play an important role in the physiology of the synovium by producing certain components of the synovial fluid and articular cartilage. In rheumatoid arthritis (RA), however, fibroblasts become a key driver of synovial inflammation and joint damage. Because of this, there has been recent interest in FLS as a therapeutic target in RA to avoid side effects such as systemic immune suppression associated with many existing RA treatments. In this review, we describe how approved treatments for RA affect FLS signaling and function and discuss the effects of investigational FLS-targeted drugs for RA.

An orally available small molecule that targets soluble TNF to deliver anti-TNF biologic-like efficacy in rheumatoid arthritis

Tumor necrosis factor (TNF) is a pleiotropic cytokine belonging to a family of trimeric proteins with both proinflammatory and immunoregulatory functions. TNF is a key mediator in autoimmune diseases and during the last couple of decades several biologic drugs have delivered new therapeutic options for patients suffering from chronic autoimmune diseases such as rheumatoid arthritis and chronic inflammatory bowel disease. Attempts to design small molecule therapies directed to this cytokine have not led to approved products yet. Here we report the discovery and development of a potent small molecule inhibitor of TNF that was recently moved into phase 1 clinical trials. The molecule, SAR441566, stabilizes an asymmetrical form of the soluble TNF trimer, compromises downstream signaling and inhibits the functions of TNF in vitro and in vivo. With SAR441566 being studied in healthy volunteers we hope to deliver a more convenient orally bioavailable and effective treatment option for patients suffering with chronic autoimmune diseases compared to established biologic drugs targeting TNF.

Inhibitory Effects of Cold Atmospheric Plasma on Inflammation and Tumor-Like Feature of Fibroblast-Like Synoviocytes from Patients with Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, debilitating systemic disease characterized by chronic inflammation and progressive joint destruction. Fibroblast-like synoviocytes (FLSs) are one of the most important players in the pathophysiology of RA, acting like tumor cells and secreting inflammatory cytokines. Previous research has shown that cold atmospheric plasma (CAP) inhibits cancer cells and may have anti-inflammatory properties. This study examined the effects of argon plasma jet-produced CAP on the suppression of invasion and inflammation caused by cultured RA-FLS. The findings revealed that CAP reduced cell viability and elevated the percentage of apoptotic RA-FLS by producing reactive oxygen species. Carboxyfluorescein diacetate succinimidyl ester (CFSE) staining confirmed that CAP could decrease the proliferation of RA-FLS. Furthermore, CAP effectively reduced the production of inflammatory factors (e.g., NF-κB and IL-6) as well as destructive factors like receptor activator of nuclear factor kappa-B ligand (RANKL) and matrix metalloproteinases-3 (MMP-3). These data suggest that CAP could be a promising treatment for slowing the progression of RA by reducing tumor-like features and inflammation in RA-FLS.

SLAMF8 promotes the proliferation and migration of synovial fibroblasts by regulating the ERK/MMPs signalling pathway

Rheumatoid arthritis is troublesome to treat effectively and often requires concomitant long-term treatment. Meanwhile, synovial fibroblasts could induce inflammation response and lead to joint erosion, finally causing progressive joint destruction, disability, and increased mortality. This study focussed on the role of SLAM family member 8 (SLAMF8) in mediating cell function from rheumatoid arthritis synovial fibroblasts stimulated with TNF-α. Cell Counting Kit-8 (CCK-8) and colony-forming unit assay were used to evaluate cell proliferation. SLAMF8 expression was analysed by reverse transcription-quantitative PCR (RT-qPCR) and western blot. Annexin V-FITC/PI double staining was used to measure the apoptosis rate. The cell migration and invasion in TNF-α-stimulated MH7A (human rheumatoid arthritis synovial cell line) and HFLS-RA cells (human fibroblast-like synoviocytes: rheumatoid arthritis) were tested via wound healing assay and transwell migration assay. In the present study, after TNF-α treatments, the SLAMF8 mRNA and protein expression in both MH7A and HFLS-RA cell lines have a time-dependent increase. The attenuation of SLAMF8 ameliorated TNF-α-induced proliferation, invasion and migration in MH7A and HFLS-RA cells. Simultaneously, when SLAMF8 was silenced, the expression of p-ERK, MMP-1, and MMP-13 was suppressed significantly. In summary, these results indicated that the knockdown of the SLAMF8 significantly attenuated TNF-α-induced proinflammatory responses in MH7A and HFLS-RA cells. Therefore, SLAMF8 exhibits therapeutic potential for the management of inflammation in rheumatoid arthritis.

The Janus kinase inhibitor (baricitinib) suppresses the rheumatoid arthritis active marker gliostatin/thymidine phosphorylase in human fibroblast-like synoviocytes

Gliostatin/thymidine phosphorylase (GLS/TP) is known to have angiogenic and arthritogenic activities in the pathogenesis of rheumatoid arthritis (RA). The novel oral Janus kinase (JAK) inhibitor baricitinib has demonstrated high efficacy in RA. However, the effect of baricitinib on fibroblast-like synoviocytes (FLSs), a key component of invasive synovitis, has not been still elucidated. This study investigated whether GLS/TP production could be regulated by JAK/signal transducers and activators of transcription (STAT) signaling in FLSs derived from patients with RA. FLSs were cultured and stimulated by interferon (IFN)γ in the presence of baricitinib. Expression levels of GLS/TP were determined using reverse transcription-polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA), and immunocytochemistry. Phosphorylation of STAT proteins was investigated by Western blot. In cultured FLSs, GLS/TP mRNA and protein levels were significantly induced by treatment with IFNγ and these inductions were suppressed by baricitinib treatment. Baricitinib inhibited IFNγ-induced STAT1 phosphorylation, while JAK/STAT activation played a pivotal role in IFNγ-mediated GLS/TP upregulation in RA. These results suggested that baricitinib suppressed IFNγ-induced GLS/TP expression by inhibiting JAK/STAT signaling, resulting in the attenuation of neovascularization, synovial inflammation, and cartilage destruction.

Euphorbia Factor L2 ameliorates the Progression of K/BxN Serum-Induced Arthritis by Blocking TLR7 Mediated IRAK4/IKKβ/IRF5 and NF-kB Signaling Pathways

Toll like receptor (TLR)s have a central role in regulating innate immunity and their activation have been highlighted in the pathogenesis of rheumatoid arthritis (RA). EFL2, one of diterpenoids derived from Euphorbia seeds, is nearly unknown expect for its improving effect on acute lung injury. Our present study aimed to investigate EFL2's pharmacokinetic features, its therapeutic effect on rheumatoid arthritis, and explored the potential anti-arthritic mechanisms. K/BxN serum transfer arthritis (STA) murine model was used to assess EFL2's anti-arthritic effects. We also applied UPLC-MS method to measure the concentrations of EFL2 in plasma. The inhibitory effects of this compound on inflammatory cells infiltration and activation were determined by flow cytometry analysis and quantitative real-time polymerase chain reaction (qRT-PCR) in vivo, and immunochemistry staining and ELISA in murine macrophages and human PBMCs in vitro, respectively. The mechanism of EFL2 on TLRs mediated signaling pathway was evaluated by PCR array, Western blot, plasmid transfection and confocal observation. Intraperitoneal (i.p.) injection of EFL2, instead of oral administration, could effectively ameliorate arthritis severity of STA mice. The inflammatory cells migration and infiltration into ankles were also significantly blocked by EFL2, accompanied with dramatically reduction of chemokines mRNA expression and pro-inflammatory cytokines production. In vivo PCR microarray indicated that EFL2 exerted anti-arthritis bioactivity by suppressing TLR7 mediated signaling pathway. In vitro study confirmed the inhibitory effects of EFL2 on TLR7 or TLR3/7 synergistically induced inflammatory cytokines secretion in murine macrophages and human PBMCs. In terms of molecular mechanism, we further verified that EFL2 robustly downregulated TLR7 mediated IRAK4-IKKβ-IRF5 and NF-κB signaling pathways activation, and blocked IRF5 and p65 phosphorylation and translocation activity. Taken together, our data indicate EFL2's therapeutic potential as a candidate for rheumatoid arthritis and other TLR7-dependent diseases.

Cytokine Networks in the Pathogenesis of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic systemic inflammation causing progressive joint damage that can lead to lifelong disability. The pathogenesis of RA involves a complex network of various cytokines and cells that trigger synovial cell proliferation and cause damage to both cartilage and bone. Involvement of the cytokines tumor necrosis factor (TNF)-α and interleukin (IL)-6 is central to the pathogenesis of RA, but recent research has revealed that other cytokines such as IL-7, IL-17, IL-21, IL-23, granulocyte macrophage colony-stimulating factor (GM-CSF), IL-1β, IL-18, IL-33, and IL-2 also play a role. Clarification of RA pathology has led to the development of therapeutic agents such as biological disease-modifying anti-rheumatic drugs (DMARDs) and Janus kinase (JAK) inhibitors, and further details of the immunological background to RA are emerging. This review covers existing knowledge regarding the roles of cytokines, related immune cells and the immune system in RA, manipulation of which may offer the potential for even safer and more effective treatments in the future.

Attenuation of rheumatoid arthritis through the inhibition of caspase3/GSDME-mediated pyroptosis induced by TNF-α

Objective

To determine the role of gasdermin E (GSDME)–mediated pyroptosis in the pathogenesis and progression of rheumatoid arthritis (RA), and to explore the potential of GSDME as a therapeutic target in RA.

Methods

The expression and activation of caspase 3 and GSDME in the synovium, macrophages, and monocytes of RA patients were determined by immunohistochemistry, immunofluorescence, and Western blot analysis. The correlation of activated GSDME with RA disease activity was evaluated. The pyroptotic ability of monocytes from RA patients was tested, and the effect of tumor necrosis factor (TNF) on caspase 3/GSDME‐mediated pyroptosis of monocytes and macrophages was investigated. In addition, collagen‐induced arthritis (CIA) was induced in mice lacking Gsdme, and the incidence and severity of arthritis were assessed.

Results

Compared to cells from healthy controls, monocytes and synovial macrophages from RA patients showed increased expression of activated caspase 3, GSDME, and the N‐terminal fragment of GSDME (GSDME‐N). The expression of GSDME‐N in monocytes from RA patients correlated positively with disease activity. Monocytes from RA patients with higher GSDME levels were more susceptible to pyroptosis. Furthermore, TNF induced pyroptosis in monocytes and macrophages by activating the caspase 3/GSDME pathway. The use of a caspase 3 inhibitor and silencing of GSDME significantly blocked TNF‐induced pyroptosis. Gsdme deficiency effectively alleviated arthritis in a mouse model of CIA.

Conclusion

These results support the notion of a pathogenic role of GSDME in RA and provide an alternative mechanism for RA pathogenesis involving TNF, which activates GSDME‐mediated pyroptosis of monocytes and macrophages in RA. In addition, targeting GSDME might be a potential therapeutic approach for RA.

Critical Role of Synovial Tissue-Resident Macrophage and Fibroblast Subsets in the Persistence of Joint Inflammation

Rheumatoid arthritis (RA) is a chronic prototypic immune-mediated inflammatory disease which is characterized by persistent synovial inflammation, leading to progressive joint destruction. Whilst the introduction of targeted biological drugs has led to a step change in the management of RA, 30-40% of patients do not respond adequately to these treatments, regardless of the mechanism of action of the drug used (ceiling of therapeutic response). In addition, many patients who acheive clinical remission, quickly relapse following the withdrawal of treatment. These observations suggest the existence of additional pathways of disease persistence that remain to be identified and targeted therapeutically. A major barrier for the identification of therapeutic targets and successful clinical translation is the limited understanding of the cellular mechanisms that operate within the synovial microenvironment to sustain joint inflammation. Recent insights into the heterogeneity of tissue resident synovial cells, including macropahges and fibroblasts has revealed distinct subsets of these cells that differentially regulate specific aspects of inflammatory joint pathology, paving the way for targeted interventions to specifically modulate the behaviour of these cells. In this review, we will discuss the phenotypic and functional heterogeneity of tissue resident synovial cells and how this cellular diversity contributes to joint inflammation. We discuss how critical interactions between tissue resident cell types regulate the disease state by establishing critical cellular checkpoints within the synovium designed to suppress inflammation and restore joint homeostasis. We propose that failure of these cellular checkpoints leads to the emergence of imprinted pathogenic fibroblast cell states that drive the persistence of joint inflammation. Finally, we discuss therapeutic strategies that could be employed to specifically target pathogenic subsets of fibroblasts in RA.

New Insights From Single-Cell Sequencing Data: Synovial Fibroblasts and Synovial Macrophages in Rheumatoid Arthritis

Single-cell RNA sequencing (scRNA-seq) technology can analyze the transcriptome expression level of cells with high-throughput from the single cell level, fully show the heterogeneity of cells, and provide a new way for the study of multicellular biological heterogeneity. Synovitis is the pathological basis of rheumatoid arthritis (RA). Synovial fibroblasts (SFs) and synovial macrophages are the core target cells of RA, which results in the destruction of articular cartilage, as well as bone. Recent scRNA-seq technology has made breakthroughs in the differentiation and development of two types of synovial cells, identification of subsets, functional analysis, and new therapeutic targets, which will bring remarkable changes in RA treatment.

Promising Therapeutic Targets for Treatment of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a systemic poly-articular chronic autoimmune joint disease that mainly damages the hands and feet, which affects 0.5% to 1.0% of the population worldwide. With the sustained development of disease-modifying antirheumatic drugs (DMARDs), significant success has been achieved for preventing and relieving disease activity in RA patients. Unfortunately, some patients still show limited response to DMARDs, which puts forward new requirements for special targets and novel therapies. Understanding the pathogenetic roles of the various molecules in RA could facilitate discovery of potential therapeutic targets and approaches. In this review, both existing and emerging targets, including the proteins, small molecular metabolites, and epigenetic regulators related to RA, are discussed, with a focus on the mechanisms that result in inflammation and the development of new drugs for blocking the various modulators in RA.

Anti-tumor necrosis factor-alpha therapy for refractory uveitic optic disk neovascularization in active non-infectious posterior and panuveitis

PURPOSE

Neovascularization of the optic disk (NVD) is mainly a complication of ischemic retinal disorders and of uveitis with vascular occlusion. Rarely, NVD may develop in patients with uveitis in the absence of retinal ischemia. This report aims to present our long-term experience of treating refractory uveitic NVD (uNVD) with adalimumab in three patients with active non-infectious posterior or panuveitis.

METHODS

Observational case series was collected from institutional tertiary referral center. Patients with chronic refractory uNVD who completed 24 months of follow-up were included.

RESULTS

uNVD was diagnosed on first presentation in all patients (3 eyes). Mean age at presentation was 29 years (median 20, range 18-49). Mean duration of complaints before presentation was 18.7 weeks (median 24, range 4-28). Uveitis was idiopathic in two patients and secondary to Behçet disease in one. All eyes had concomitant cystoid macular edema. Additional posterior segment signs included optic disk hemorrhage, preretinal hemorrhage and vitreous hemorrhage. All eyes showed retinal vascular leakage and macular leakage with no evidence of capillary non-perfusion. All patients were treated with systemic steroids and steroid-sparing agent. Because of NVD refractoriness, anti-TNF-α therapy was introduced at a mean of 24.7 weeks after first presentation (median 20, range 14-40). Complete regression of NVD was observed at a mean of 34.7 weeks (median 32, range 8-64) following adalimumab institution. Mean follow-up time after starting anti-TNF-α agents was 31.3 months.

CONCLUSIONS

Our results suggest that targeting TNF-α achieves long-term control of uveitic NVD refractory to conventional treatments.

Interleukin-24 regulates mucosal remodeling in inflammatory bowel diseases

Background

Recently, increased interleukin (IL)-24 expression has been demonstrated in the colon biopsies of adult patients with inflammatory bowel disease (IBD). However, the role of IL-24 in the pathomechanism of IBD is still largely unknown.

Methods

Presence of IL-24 was determined in the samples of children with IBD and in the colon of dextran sodium sulfate (DSS) treated mice. Effect of inflammatory factors on IL24 expression was determined in peripheral blood (PBMCs) and lamina propria mononuclear cells (LPMCs). Also, the impact of IL-24 was investigated on HT-29 epithelial cells and CCD-18Co colon fibroblasts. Expression of tissue remodeling related genes was investigated in the colon of wild type (WT) mice locally treated with IL-24 and in the colon of DSS treated WT and Il20rb knock out (KO) mice.

Results

 Increased amount of IL-24 was demonstrated in the serum and colon samples of children with IBD and DSS treated mice compared to that of controls. IL-1β, LPS or H₂O₂ treatment increased the expression of IL24 in PBMCs and LPMCs. IL-24 treatment resulted in increased amount of TGF-β and PDGF-B in HT-29 cells and enhanced the expression of extracellular matrix (ECM)-related genes and the motility of CCD-18Co cells. Similarly, local IL-24 treatment increased the colonic Tgfb1 and Pdgfb expression of WT mice. Moreover, expression of pro-fibrotic Tgfb1 and Pdgfb were lower in the colon of DSS treated Il20rb KO compared to that of WT mice. The disease activity index of colitis was less severe in DSS treated Il20rb KO compared to WT mice.

Conclusion

Our study suggest that IL-24 may play a significant role in the mucosal remodeling of patients with IBD by promoting pro-fibrotic processes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-02890-7.

In vitro responses to platelet-rich-plasma are associated with variable clinical outcomes in patients with knee osteoarthritis

Autologous blood-derived products such as platelet-rich plasma (PRP) are widely used to treat musculoskeletal conditions, including knee osteoarthritis (OA). However, the clinical outcomes after PRP administration are often variable, and there is limited information about the specific characteristics of PRP that impact bioactivity and clinical responses. In this study, we aimed to develop an integrative workflow to evaluate responses to PRP in vitro, and to assess if the in vitro responses to PRP are associated with the PRP composition and clinical outcomes in patients with knee OA. To do this, we used a coculture system of macrophages and fibroblasts paired with transcriptomic analyses to comprehensively characterize the modulation of inflammatory responses by PRP in vitro. Relying on patient-reported outcomes and achievement of minimal clinically important differences in OA patients receiving PRP injections, we identified responders and non-responders to the treatment. Comparisons of PRP from these patient groups allowed us to identify differences in the composition and in vitro activity of PRP. We believe that our integrative workflow may enable the development of targeted approaches that rely on PRP and other orthobiologics to treat musculoskeletal pathologies.

Sensitization of knee-innervating sensory neurons by tumor necrosis factor-α-activated fibroblast-like synoviocytes: an in vitro, coculture model of inflammatory pain

ABSTRACT

Pain is a principal contributor to the global burden of arthritis with peripheral sensitization being a major cause of arthritis-related pain. Within the knee joint, distal endings of dorsal root ganglion neurons (knee neurons) interact with fibroblast-like synoviocytes (FLS) and the inflammatory mediators they secrete, which are thought to promote peripheral sensitization. Correspondingly, RNA sequencing has demonstrated detectable levels of proinflammatory genes in FLS derived from arthritis patients. This study confirms that stimulation with tumor necrosis factor (TNF-α) results in expression of proinflammatory genes in mouse and human FLS (derived from osteoarthritis and rheumatoid arthritis patients), as well as increased secretion of cytokines from mouse TNF-α-stimulated FLS (TNF-FLS). Electrophysiological recordings from retrograde labelled knee neurons cocultured with TNF-FLS, or supernatant derived from TNF-FLS, revealed a depolarized resting membrane potential, increased spontaneous action potential firing, and enhanced TRPV1 function, all consistent with a role for FLS in mediating the sensitization of pain-sensing nerves in arthritis. Therefore, data from this study demonstrate the ability of FLS activated by TNF-α to promote neuronal sensitization, results that highlight the importance of both nonneuronal and neuronal cells to the development of pain in arthritis.

Cell-specific epigenetic drivers of pathogenesis in rheumatoid arthritis

Rheumatoid arthritis is a complex, inflammatory autoimmune disease, which is characterized by pain, swelling and joint damage driven by the altered behavior of a number of different cell types such as synovial fibroblasts macrophages and lymphocytes. The mechanism underlying pathogenesis is unclear but increasing evidence points to altered epigenetic regulation within these cell types which promotes the activated destructive behavior that underlies disease pathogenesis. This review summarizes the key epigenetic modifications in the most important cells types in rheumatoid arthritis, which are associated with disease activity. We also discuss emerging avenues of research focusing on readers of epigenetic markers which may serve to be potential therapeutic targets.

Fibroblast-like synoviocytes in rheumatoid arthritis: Surface markers and phenotypes

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease that mainly affects synovial joints. During the course of RA, the synovium transforms into hyperplastic invasive tissue, leading to cartilage and bone destruction. Fibroblast-like synoviocytes (FLS) in the synovial lining develop aggressive phenotypes and produce pathogenic mediators that lead to the occurrence and progression of disease, playing a major role in RA pathophysiology. Therefore, research on FLS has become the main focus within the RA field. With technical advances and the development of multi-omics comprehensive analysis approaches, it has become possible to identify different FLS subsets via high-throughput sequencing and investigate differences between FLS phenotypes, allowing for the detailed study of RA pathogenesis. This review summarizes recent works on FLS subtypes and the surface marker proteins identified for different subtypes, providing a theoretical basis and reference for future studies on FLS in RA. The current work also addresses the clinical potential of FLS surface markers in RA based on related research from other fields.

Analysis of interleukin-1 receptor associated kinase-3 (IRAK3) function in modulating expression of inflammatory markers in cell culture models: A systematic review and meta-analysis

BACKGROUND

IRAK3 is a critical modulator of inflammation in innate immunity. IRAK3 is associated with many inflammatory diseases, including sepsis, and is required in endotoxin tolerance to maintain homeostasis of inflammation. The impact of IRAK3 on inflammatory markers such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in cell culture models remains controversial.

OBJECTIVE

To analyse temporal effects of IRAK3 on inflammatory markers after one- or two-challenge interventions in cell culture models.

METHODS

A systematic search was performed to identify in vitro cell studies reporting outcome measures of expression of IRAK3 and inflammatory markers. Meta-analyses were performed where sufficient data were available. Comparisons of outcome measures were performed between different cell lines and human and mouse primary cells.

RESULTS

The literature search identified 7766 studies for screening. After screening titles, abstracts and full-texts, a total of 89 studies were included in the systematic review.

CONCLUSIONS

The review identifies significant effects of IRAK3 on decreasing NF-κB DNA binding activity in cell lines, TNF-α protein level at intermediate time intervals (4h-15h) in cell lines or at long term intervals (16h-48h) in mouse primary cells following one-challenge. The patterns of TNF-α protein expression in human cell lines and human primary cells in response to one-challenge are more similar than in mouse primary cells. Meta-analyses confirm a negative correlation between IRAK3 and inflammatory cytokine (IL-6 and TNF-α) expression after two-challenges.

Vitamin D as a Key Player in Modulating Rheumatoid Arthritis-derived Immune Response

Rheumatoid arthritis (RA) is a systemic inflammatory disease with chronic nature of joints related to autoimmunity. Vitamin D was found to modulate cell growth, function of immune cells and anti-inflammatory action. The aims of that study were to investigate serum level of vitamin D and some cytokines and to identify the correlation between vitamin D and these cytokines in RA. Totally 40 RA patients without vitamin D supplement were involved in this study. Serum level of vitamin D, interleukin-6 (IL-6), IL-10, IL-35, C-reactive protein (CRP) and tumor necrosis factor α (TNF-α), all of them were measure in all patients by enzyme-linked immunosorbent assay (ELISA). Patients were classified according to Vitamin D levels into two groups; RA patients with Vit. D deficiency (n=25) and RA patients with Vit. D sufficiency (n=15). IL-6 was lower significantly (P = 0.03) in RA patients with Vit. D sufficiency than RA patients with Vit. D deficiency. IL-10 and IL-35 were higher significantly (P = 0.0234, P = 0.0356 respectively) in RA patients with Vit. D sufficiency than RA patients with Vit. D deficiency. Vit. D was significantly positively correlated with both IL-10 (r = 0.4516, P = 0.0034) and IL-35 (r = 0.3424, P = 0.0329) and negatively correlated with IL-6 (r = -0.3188, P = 0.0479). Sufficient serum level of Vit. D is correlated with higher level of anti-inflammatory cytokines (IL-10 and IL-35) and lower level of IL-6. This support the immunomodulatory effect of Vit. D in RA.

Persistent inflammatory and non-inflammatory mechanisms in refractory rheumatoid arthritis

Despite nearly three decades of advances in the management of rheumatoid arthritis (RA), a substantial minority of patients are exposed to multiple DMARDs without necessarily benefitting from them; a group of patients variously designated as having 'difficult to treat', 'treatment-resistant' or 'refractory' RA. This Review of refractory RA focuses on two types of patients: those for whom multiple targeted therapies lack efficacy and who have persistent inflammatory pathology, which we designate as persistent inflammatory refractory RA (PIRRA); and those with supposed refractory RA who have continued disease activity that is predominantly independent of objective evidence of inflammation, which we designate as non-inflammatory refractory RA (NIRRA). These two types of disease are not mutually exclusive, but identifying those individuals with predominant PIRRA or NIRRA is important, as it informs distinct treatment and management approaches. This Review outlines the clinical differences between PIRRA and NIRRA, the genetic and epigenetic mechanisms and immune pathways that might contribute to the immunopathogenesis of recalcitrant synovitis in PIRRA, and a possible basis for non-inflammatory symptomatology in NIRRA. Future approaches towards the definition of refractory RA and the application of single-cell and integrated omics technologies to the identification of refractory RA endotypes are also discussed.

Tumor Necrosis Factor Receptors: Pleiotropic Signaling Complexes and Their Differential Effects

Since its discovery in 1975, TNFα has been a subject of intense study as it plays significant roles in both immunity and cancer. Such attention is well deserved as TNFα is unique in its engagement of pleiotropic signaling via its two receptors: TNFR1 and TNFR2. Extensive research has yielded mechanistic insights into how a single cytokine can provoke a disparate range of cellular responses, from proliferation and survival to apoptosis and necrosis. Understanding the intracellular signaling pathways induced by this single cytokine via its two receptors is key to further revelation of its exact functions in the many disease states and immune responses in which it plays a role. In this review, we describe the signaling complexes formed by TNFR1 and TNFR2 that lead to each potential cellular response, namely, canonical and non-canonical NF-κB activation, apoptosis and necrosis. This is followed by a discussion of data from in vivo mouse and human studies to examine the differential impacts of TNFR1 versus TNFR2 signaling.

Chronic exposure to TNF reprograms cell signaling pathways in fibroblast-like synoviocytes by establishing long-term inflammatory memory

Fibroblast-like synoviocytes (FLS) play a critical role in the pathogenesis of rheumatoid arthritis (RA). Chronic inflammation induces transcriptomic and epigenetic modifications that imparts a persistent catabolic phenotype to the FLS, despite their dissociation from the inflammatory environment. We analyzed high throughput gene expression and chromatin accessibility data from human and mouse FLS from our and other studies available on public repositories, with the goal of identifying the persistently reprogrammed signaling pathways driven by chronic inflammation. We found that the gene expression changes induced by short-term tumor necrosis factor-alpha (TNF) treatment were largely sustained in the FLS exposed to chronic inflammation. These changes that included both activation and repression of gene expression, were accompanied by the remodeling of chromatin accessibility. The sustained activated genes (SAGs) included established pro-inflammatory signaling components known to act at multiple levels of NF-kappaB, STAT and AP-1 signaling cascades. Interestingly, the sustained repressed genes (SRGs) included critical mediators and targets of the BMP signaling pathway. We thus identified sustained repression of BMP signaling as a unique constituent of the long-term inflammatory memory induced by chronic inflammation. We postulate that simultaneous targeting of these activated and repressed signaling pathways may be necessary to combat RA persistence.

Innate Lymphocytes in Inflammatory Arthritis

Inflammatory arthritis (IA) refers to a group of chronic diseases, including rheumatoid arthritis (RA), psoriatic arthritis (PsA), ankylosing spondylitis (AS), and other spondyloarthritis (SpA). IA is characterized by autoimmune-mediated joint inflammation and is associated with inflammatory cytokine networks. Innate lymphocytes, including innate-like lymphocytes (ILLs) expressing T or B cell receptors and innate lymphoid cells (ILCs), play important roles in the initiation of host immune responses against self-antigens and rapidly produce large amounts of cytokines upon stimulation. TNF (Tumor Necrosis Factor)-α, IFN (Interferon)-γ, Th2-related cytokines (IL-4, IL-9, IL-10, and IL-13), IL-17A, IL-22, and GM-CSF are involved in IA and are secreted by ILLs and ILCs. In this review, we focus on the current knowledge of ILL and ILC phenotypes, cytokine production and functions in IA. A better understanding of the roles of ILLs and ILCs in IA initiation and development will ultimately provide insights into developing effective strategies for the clinical treatment of IA patients.

IRF9 Affects the TNF-Induced Phenotype of Rheumatoid-Arthritis Fibroblast-Like Synoviocytes via Regulation of the SIRT-1/NF-κB Signaling Pathway

OBJECTIVE

To discuss how IRF9 affects the fibroblast-like synoviocytes (FLS) in TNF-induced rheumatoid arthritis (RA) via the SIRT-1/NF-κB signaling pathway.

METHODS

RA-FLS were isolated and divided into control, sh-IRF9, TNF, TNF + sh-Ctrl, TNF + sh-IRF9, TNF + sh-SIRT1, and TNF + sh-IRF9 + sh-SIRT1 groups. Biological features of FLS were evaluated by MTT, wound healing, and Transwell assays, respectively. Cell apoptosis and cycle were assessed flow cytometrically. Inflammatory cytokines were determined through enzyme-linked immunosorbent assay (ELISA), while IRF9 expression and SIRT1/NF-κB signaling pathway activity were measured by Western blotting.

RESULTS

TNF increased IRF9 expression as well as NF-κB signaling activity and down-regulated SIRT1 of RA-FLS. Silencing IRF9 resulted in up-regulation of SIRT1 and blocked NF-κB signaling, with significant decreases in TNF-induced cell viability, migration, and invasion, prominent enhancement in apoptosis and the proportion of cells in G0/G1 phase, but a decrease in the proportion of cells in S and G2/M phases, and reduced levels of inflammatory cytokines. However, these changes were totally abolished after silencing SIRT1, i.e., the IRF9 shRNA-induced inhibitory effect on the growth of RA-FLS was reversed.

CONCLUSION

Silencing IRF9 curbs the activity of the NF-κB signaling pathway via up-regulating SIRT-1, to further suppress TNF-induced changes in the malignant features of RA-FLS, and the secretion of inflammatory cytokines, with the promoted apoptosis.