Mechanisms of tissue damage in arthritis

Manual acupuncture ameliorates inflammatory pain by upregulating adenosine A3 receptor in complete Freund's adjuvant-induced arthritis rats

BACKGROUND

Adenosine A3 receptor (A3R) exerts analgesic, anti-inflammatory, and anti-nociceptive effects. In this study, we determined the analgesic mechanism of manual acupuncture (MA) in rats with complete Freund's adjuvant (CFA)-induced arthritis and explored whether MA ameliorates inflammation in these rats by upregulating A3R.

METHODS

Sixty Sprague Dawley (SD) rats were randomly divided into the following groups: Control, CFA, CFA + MA, CFA + sham MA, CFA + MA + DMSO, CFA + MA + IB-MECA, and CFA + MA + Reversine groups. The arthritis rat model was induced by injecting CFA into the left ankle joints. Thereafter, the rats were subjected to MA (ST36 acupoint) for 3 days. The clinical indicators paw withdrawal latency (PWL), paw withdrawal threshold (PWT), and open field test (OFT) were used to determine the analgesic effect of MA. In addition, to explore the effect of A3R on inflammation after subjecting arthritis rats to MA, IB-MECA (A3R agonist) and Reversine (A3R antagonist) were injected into ST36 before MA.

RESULTS

MA ameliorated the pathological symptoms of CFA-induced arthritis, including the pain indicators PWL and PWT, number of rearing, total ambulatory distance, and activity trajectory. Furthermore, after MA, the mRNA and protein expression of A3R was upregulated in CFA-induced arthritis rats. In contrast, the protein levels of TNF-α, IL-1β, Rap1, and p-p65 were downregulated after MA. Interestingly, the A3R agonist and antagonist further downregulated and upregulated inflammatory cytokine expression, respectively, after MA. Furthermore, the A3R antagonist increased the degree of ankle swelling after MA.

CONCLUSION

MA can alleviate inflammatory pain by inhibiting the NF-κB signaling pathway via upregulating A3R expression of the superficial fascia of the ST36 acupoint site in CFA-induced arthritis rats.

Amino Acids Fueling Fibroblast-Like Synoviocyte Activation and Arthritis By Regulating Chemokine Expression and Leukocyte Migration

OBJECTIVE

We analyzed the impact of amino acid (AA) availability on the inflammatory response in arthritis.

METHODS

We stimulated rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLSs) with tumor necrosis factor (TNF) in the presence or absence of proteinogenic AAs and measured their response by QuantSeq 3' messenger RNA sequencing, quantitative polymerase chain reaction, and enzyme-linked immunosorbent assay. Signal transduction events were determined by Western blot. We performed K/BxN serum transfer arthritis in mice receiving a normal and a low-protein diet and analyzed arthritis clinically and histologically.

RESULTS

Deprivation of AAs decreased the expression of a specific subset of genes, including the chemokines CXCL10, CCL2, and CCL5 in TNF-stimulated FLSs. Mechanistically, the presence of AAs was required for the TNF-induced activation of an interferon regulatory factor 1 (IRF1)-STAT1 signaling circuit that drives the expression of chemotactic factors. The expression of IRF1 and the IRF1-dependent gene set in FLSs was highly correlated with the presence of inflammatory cells in human RA, emphasizing the important role of this AA-dependent pathway in inflammatory cell recruitment to the synovial tissue. Finally, we show that mice receiving a low-protein diet expressed less IRF1 in the inflamed synovium and consequently developed reduced clinical and histologic signs of arthritis.

CONCLUSION

AA deprivation reduces the severity of arthritis by suppressing the expression of IRF1-STAT1-driven chemokines, which are crucial for leukocyte recruitment to the arthritic joint. Overall, our study provides novel insights into critical determinants of inflammatory arthritis and may pave the way for dietary intervention trials in RA.

Increased 18F-FAPI uptake in bones and joints of lung cancer patients: characteristics and distributions

OBJECTIVE

This study investigated the distribution and characteristics of various bone and joint lesions on 18F-FAPI PET/CT in lung cancer patients.

METHODS

Seventy-four lung cancer patients who underwent 18F-FAPI PET/CT were reviewed. Bone and joint lesions with elevated 18F-FAPI uptake were recorded and analyzed. The distribution and maximum uptake value (SUVmax) of different benign lesions or bone metastases were presented. In addition, the SUVmax of bone metastases on 18F-FDG and 18F-FAPI-04 PET/CT were also compared.

RESULTS

In 53 patients, a total of 262 lesions presented 18F-FAPI accumulation. Bone metastases were mainly in vertebrae, pelvis, and ribs, while benign lesions were in vertebral margins, alveolar bone, and shoulder joints. The SUVmax of bone metastases was significantly higher than that of benign lesions ([Formula: see text] vs. [Formula: see text], [Formula: see text]), with NSCLC cases having higher SUVmax values than SCLC cases ([Formula: see text] vs. [Formula: see text], [Formula: see text]). Among benign lesions, arthritis and periodontitis demonstrated higher SUVmax than degenerative lesions (arthritis: [Formula: see text]; periodontitis: [Formula: see text]; degenerative diseases: [Formula: see text]; [Formula: see text] and [Formula: see text], respectively). The SUVmax of bone metastases was comparable between 18F-FDG and 18F-FAPI PET/CT. However, 18F-FAPI PET/CT was found to be superior in identifying cranial metastases compared to 18F-FDG PET/CT (TBRmet/brain: [Formula: see text] vs. [Formula: see text], [Formula: see text]).

CONCLUSION

This study demonstrated that 18F-FAPI PET/CT is a valuable imaging modality for detecting bone and joint lesions in lung cancer patients. The SUVmax of malignant lesions was higher than that of benign lesions, but cannot accurately distinguish benign and malignant lesions. The uptake of FAPI differs among lesions with different pathological types.

Healthy and Osteoarthritis-Affected Joints Facing the Cellular Crosstalk

Osteoarthritis (OA) is a chronic, progressive, severely debilitating, and multifactorial joint disease that is recognized as the most common type of arthritis. During the last decade, it shows an incremental global rise in prevalence and incidence. The interaction between etiologic factors that mediate joint degradation has been explored in numerous studies. However, the underlying processes that induce OA remain obscure, largely due to the variety and complexity of these mechanisms. During synovial joint dysfunction, the osteochondral unit undergoes cellular phenotypic and functional alterations. At the cellular level, the synovial membrane is influenced by cartilage and subchondral bone cleavage fragments and extracellular matrix (ECM) degradation products from apoptotic and necrotic cells. These "foreign bodies" serve as danger-associated molecular patterns (DAMPs) that trigger innate immunity, eliciting and sustaining low-grade inflammation in the synovium. In this review, we explore the cellular and molecular communication networks established between the major joint compartments-the synovial membrane, cartilage, and subchondral bone of normal and OA-affected joints.

Effect of osteoarthritis on alveolar bone loss in experimental periodontitis in rats

BACKGROUND

There is scarce information about the relationship between periodontal disease and osteoarthritis. This study investigated the effect of surgically induced osteoarthritis on alveolar bone loss in experimental periodontitis in rats.

METHODS

12 rats were divided into test and control groups. On day 1, the animals were anaesthetized, and silk ligatures were ligated around 6 maxillary posterior teeth in each animal from both groups. Surgical induction of osteoarthritis was performed on the left knees in the test group. No knee surgeries were performed in the control group. The ligatures were kept in place for 30 days, at which time the animals were euthanatized, and the maxillae and knee joints were harvested and processed for histological analysis. The alveolar bone loss was assessed using a zoom stereomicroscope.

RESULTS

The knee joint histologic sections of the control group showed normal joint features, whereas in the test group there were substantial changes typical of osteoarthritis, including wide joint spaces, prominent monocytic infiltration of the synovium, invasion of periarticular bone, and decreased chondrocyte density. Comparison of the bone height between the groups showed a significantly higher bone loss in the test than in the control group The marginal mean bone height, adjusted for covariates and the intraclass correlation between sites, was 1.19 and 0.78 mm in the test and control groups, respectively (p < .0001).

CONCLUSIONS

Surgically induced osteoarthritis leads to greater alveolar bone loss in the experimental periodontitis model in rats.

Theaflavin-3,3'-Digallate Ameliorates Collagen-Induced Arthritis Through Regulation of Autophagy and Macrophage Polarization

Purpose

Previous studies have presented that theaflavin-3,3'-digallate (TFDG), one of natural flavonoids, have protective effects on collagen-induced arthritis (CIA). Besides, it was reported that TFDG could affect inflammatory signaling pathways, like NF-κB, JNK, and so on, to ameliorate inflammation. However, the anti-inflammatory mechanisms mentioned above are common to natural flavonoid products including TFDG. Therefore, this study aimed to further investigate the other mechanisms of TFDG against CIA.

Methods

DBA/1 mice (8-10 weeks) were intravenously injected Freund's Adjuvant (100μL) at the base of tail and intraperitoneally injected PBS or different dosage of TFDG (1 mg/kg or 10 mg/kg). Then the paw and knee tissues were collected to assess the severity of joint destruction. In vitro experiments, bone marrow macrophages (BMMs) were exposed to TNF-α (10ng/mL) with or without different concentrations of TFDG (0.1μmol/L or 1.0μmol/L). Besides, the targets of TFDG were predicted with docking software and were verified through experiment.

Results

TFDG treatment could reduce M1 macrophage (pro-inflammatory) and inflammatory cytokines, such as IL-1, IL- 6 and TNF-α, both in vitro and in vivo. At the same time, the M2 macrophage (alternatively activated) polarization was promoted by TFDG. Animal experiments showed TFDG ameliorated joint destructions. For investigating the mechanisms, the targets of TFDG were predicted by bioinformatics tools. According to predictions, we hypothesized that TFDG could act with BCL-2 to weaken the interaction between BCL-2 and Beclin1. Beclin1 plays a central role in autophagy, and we found that the autophagy level of BMMs was recovered by TFDG. Besides, 3-MA, an autophagy inhibitor, could attenuate the therapeutic effect of TFDG.

Conclusion

TFDG protected against collagen-induced arthritis by attenuating the inflammation and promoting anti-inflammatory M2 macrophage polarization through controlling autophagy.

Analysis of combined deficiency of interleukin-1 and -6 versus single deficiencies in TNF-mediated arthritis and systemic bone loss

Aims

Insufficient treatment response in rheumatoid arthritis (RA) patients requires novel treatment strategies to halt disease progression. The potential benefit of combination of cytokine-inhibitors in RA is still unclear and needs further investigation. To explore the impact of combined deficiency of two major cytokines, namely interleukin (IL)-1 and IL-6, in this study double deficient mice for IL-1αβ and IL-6 were investigated in different tumour necrosis factor (TNF)-driven inflammatory bone disorders, namely peripheral arthritis and sacroiliitis, as well as systemic bone loss.

Methods

Disease course, histopathological features of arthritis, and micro-CT (µCT) bone analysis of local and systemic bone loss were assessed in 15-week-old IL1^-/-IL6^-/-hTNFtg in comparison to IL1^-/-hTNFtg, IL6^-/-hTNFtg, and hTNFtg mice. µCT bone analysis of single deficient and wild-type mice was also performed.

Results

Combined deficiency of IL-1/IL-6 markedly ameliorated TNF-mediated arthritis and bilateral sacroiliitis, but without additive benefits compared to single IL-1 deficiency. This finding confirms the important role of IL-1 and the marginal role of IL-6 in TNF-driven pathways of local joint damage, but questions the efficacy of potential combinatorial therapies of IL-1 and IL-6 in treatment of RA. In contrast, combined deficiency of IL-1/IL-6 led to an additive protective effect on TNF-driven systemic bone loss compared to single IL-1 and IL-6 deficiency. This finding clearly indicates a common contribution of both IL-1 and IL-6 in TNF-driven systemic bone loss, and points to a discrepancy of cytokine dependency in local and systemic TNF-driven mechanisms of inflammatory arthritis.

Conclusion

Combinatorial treatments in RA might provide different benefits to inflammatory local arthritis and systemic comorbidities.

Cite this article: Bone Joint Res 2022;11(7):484–493.

Practical Implementation of Artificial Intelligence-Based Deep Learning and Cloud Computing on the Application of Traditional Medicine and Western Medicine in the Diagnosis and Treatment of Rheumatoid Arthritis

Rheumatoid arthritis (RA), an autoimmune disease of unknown etiology, is a serious threat to the health of middle-aged and elderly people. Although western medicine, traditional medicine such as traditional Chinese medicine, Tibetan medicine and other ethnic medicine have shown certain advantages in the diagnosis and treatment of RA, there are still some practical shortcomings, such as delayed diagnosis, improper treatment scheme and unclear drug mechanism. At present, the applications of artificial intelligence (AI)-based deep learning and cloud computing has aroused wide attention in the medical and health field, especially in screening potential active ingredients, targets and action pathways of single drugs or prescriptions in traditional medicine and optimizing disease diagnosis and treatment models. Integrated information and analysis of RA patients based on AI and medical big data will unquestionably benefit more RA patients worldwide. In this review, we mainly elaborated the application status and prospect of AI-assisted deep learning and cloud computation-oriented western medicine and traditional medicine on the diagnosis and treatment of RA in different stages. It can be predicted that with the help of AI, more pharmacological mechanisms of effective ethnic drugs against RA will be elucidated and more accurate solutions will be provided for the treatment and diagnosis of RA in the future.

Transmembrane TNF drives osteoproliferative joint inflammation reminiscent of human spondyloarthritis

TNF plays a key role in immune-mediated inflammatory diseases including rheumatoid arthritis (RA) and spondyloarthritis (SpA). It remains incompletely understood how TNF can lead to different disease phenotypes such as destructive peripheral polysynovitis in RA versus axial and peripheral osteoproliferative inflammation in SpA. We observed a marked increase of transmembrane (tm) versus soluble (s) TNF in SpA versus RA together with a decrease in the enzymatic activity of ADAM17. In contrast with the destructive polysynovitis observed in classical TNF overexpression models, mice overexpressing tmTNF developed axial and peripheral joint disease with synovitis, enthesitis, and osteitis. Histological and radiological assessment evidenced marked endochondral new bone formation leading to joint ankylosis over time. SpA-like inflammation, but not osteoproliferation, was dependent on TNF-receptor I and mediated by stromal tmTNF overexpression. Collectively, these data indicate that TNF can drive distinct inflammatory pathologies. We propose that tmTNF is responsible for the key pathological features of SpA.

[Biologicals and small molecules for rheumatoid arthritis]

In recent years tremendous progress has been made in the therapeutic management of rheumatoid arthritis. Rheumatologists now have a large armamentarium of highly efficient drugs with different mechanisms of action at their disposal. These new drugs consist of biologicals (biological disease-modifying antirheumatic drugs, bDMARDs) as well as targeted synthetic DMARDs (tsDMARD). A common feature of these new drugs for treatment of rheumatoid arthritis is that the molecular target of the drug is known, which is not the case for conventional DMARDs. With the help of the new drugs, the therapeutic goal of inducing remission in patients with rheumatoid arthritis has become reality for many patients. Nevertheless, there is still a significant proportion of patients who do not adequately respond to all available drugs, leaving room for still further improvement. This review gives a short overview on the currently available and effective substances for the treatment of rheumatoid arthritis.

Innate immunity as the trigger of systemic autoimmune diseases

The innate immune system consists of a variety of elements controlling and participating in virtually all aspects of inflammation and immunity. It is crucial for host defense, but on the other hand its improper activation is also thought to be responsible for the generation of autoimmunity and therefore diseases such as autoimmune arthritides like rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), multiple sclerosis (MS) or inflammatory bowel disease. The innate immune system stands both at the beginning as well as the end of autoimmunity. On one hand, it regulates the activation of the adaptive immune system and the breach of self-tolerance, as antigen presenting cells (APCs), especially dendritic cells, are essential for the activation of naïve antigen specific T cells, a crucial step in the development of autoimmunity. Various factors controlling the function of dendritic cells have been identified that directly regulate lymphocyte homeostasis and in some instances the generation of organ specific autoimmunity. Moreover, microbial cues have been identified that are prerequisites for the generation of several specific autoimmune diseases. On the other hand, the innate immune system is also responsible for mediating the resulting organ damage underlying the clinical symptoms of a given autoimmune disease via production of proinflammatory cytokines that amplify local inflammation and further activate other immune or parenchymal cells in the vicinity, the generation of matrix degrading and proteolytic enzymes or reactive oxygen species directly causing tissue damage. In the last decades, molecular characterization of cell types and their subsets as well as both positive and negative regulators of immunity has led to the generation of various scenarios of how autoimmunity develops, which eventually might lead to the development of targeted interventions for autoimmune diseases. In this review, we try to summarize the elements that are contributing to the initiation and perpetuation of autoimmune responses.

Exploring inflammatory signatures in arthritic joint biopsies with Spatial Transcriptomics

Lately it has become possible to analyze transcriptomic profiles in tissue sections with retained cellular context. We aimed to explore synovial biopsies from rheumatoid arthritis (RA) and spondyloarthritis (SpA) patients, using Spatial Transcriptomics (ST) as a proof of principle approach for unbiased mRNA studies at the site of inflammation in these chronic inflammatory diseases. Synovial tissue biopsies from affected joints were studied with ST. The transcriptome data was subjected to differential gene expression analysis (DEA), pathway analysis, immune cell type identification using Xcell analysis and validation with immunohistochemistry (IHC). The ST technology allows selective analyses on areas of interest, thus we analyzed morphologically distinct areas of mononuclear cell infiltrates. The top differentially expressed genes revealed an adaptive immune response profile and T-B cell interactions in RA, while in SpA, the profiles implicate functions associated with tissue repair. With spatially resolved gene expression data, overlaid on high-resolution histological images, we digitally portrayed pre-selected cell types in silico. The RA displayed an overrepresentation of central memory T cells, while in SpA effector memory T cells were most prominent. Consequently, ST allows for deeper understanding of cellular mechanisms and diversity in tissues from chronic inflammatory diseases.

UPLC-Q-TOF/MS characterization of efficacy substances on osteoblasts differentiation and function in rat serum after administration of Wang-Bi tablet

Wang-Bi tablet (WB) is popularly used for the treatment of rheumatoid arthritis. However, few studies have been carried out on its active ingredients and mechanism. In this study, the effect of WB medicated serum on the changes in differentiation and function in osteoblast was investigated, the results showed that WB induced the production of ALP and mineralized nodules to promote the final maturation of osteoblasts and enhance the function of osteoblasts. The potential mechanism may that WB significantly inhibits gene expressions of RANKL and miR-141, up-regulates the gene expressions of RUNX2 and OPG, decreases expression of DKK-1 and increases levels of β-catenin protein to promote the activation of Wnt/β-catenin signaling pathways, which enhances osteogenesis and bone repair function. To investigate which compounds contributed to the activity and mechanisms, a total of 138 compounds were characterized from WB, and 13 parent molecules and eight metabolites in rat serum were rapidly characterized by UPLC-Q-TOF/MS. Total glycosides of paeony, loganin, α-linolenic acid, linoleic acid and naringin from WB may contribute to the actions on osteoblasts according to our study and literature review. Our research provides a method to explore the bioactive ingredients and action mechanisms of WB.

Effects of human cyclooxygenase-2 gene silencing on synovial cells of rheumatoid arthritis mediated by lentivirus

The aim of the study is to screen the effective shRNA sequence which can silence the human COX-2 expression level in synovial cells of rheumatoid arthritis (RA) patient transfected by the lentivirus. Four pairs of hCOX-2 shRNA were designed and inserted into lentivirus to form pGPHI/GFP/Neo-shRNA vector. The reconstructed virus was transfected into synovial cells derived from RA patients, and then the expression level of hCOX-2 mRNA and the protein of the inflammatory factors including prostaglandin E2 (PGE2), vascular endothelial growth factor (VEGF), interleukin-1β (IL-1β) and tumour necrosis factor alpha (TNF-α) in the supernatants were examined with real-time PCR and ELISA, respectively. There was no obvious negative influence on cell growth and morphology after hCOX-2 shRNA gene transfection mediated by lentivirus. The hCOX-2 mRNA expression level, as well as the concentration of PGE2, VEGF, IL-1β and TNF-α, decreased significantly (p < .05). RNAi mediated by lentivirus can significantly inhibit hCOX-2 mRNA expression level in synovial cells of RA patients, so as to reduce the expression of inflammatory cytokines.

Sinomenine Inhibits the Progression of Rheumatoid Arthritis by Regulating the Secretion of Inflammatory Cytokines and Monocyte/Macrophage Subsets

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory arthropathy associated with articular damage and attendant comorbidities. Even although RA treatment has advanced remarkably over the last decade, a significant proportion of patients still do not achieve sustained remission. The cause of RA is not yet known despite the many potential mechanisms proposed. It has been confirmed that RA is associated with dysregulated immune system and persistent inflammation. Therefore, management of inflammation is always the target of therapy. Sinomenine (SIN) is the prescription drug approved by the Chinese government for RA treatment. A previous study found that SIN was a robust anti-inflammation drug. In this study, we screened the different secretory cytokines using inflammation antibody arrays and qRT-PCR in both LPS-induced and SIN-treated RAW264.7 cells followed by evaluation of the ability of SIN to modulate cytokine secretion in a cell model, collagen-induced arthritis (CIA) mouse model, and RA patients. Several clinical indexes affecting the 28-joint disease activity score (DAS28) were determined before and after SIN treatment. Clinical indexes, inflammatory cytokine secretion, and DAS28 were compared among RA patients treated with either SIN or methotrexate (MTX). To explore the mechanism of SIN anti-inflammatory function, RA-associated monocyte/macrophage subsets were determined using flow cytometry in CIA mouse model and RA patients, both treated with SIN. The results demonstrated that SIN regulated IL-6, GM-CSF, IL-12 p40, IL-1α, TNF-α, IL-1β, KC (CXCL1), Eotaxin-2, IL-10, M-CSF, RANTES, and MCP-1 secretion in vivo and in vitro and reduced RA activity and DAS28 in a clinical setting. Furthermore, SIN attenuated CD11b⁺F4/80⁺CD64⁺ resident macrophages in the synovial tissue, CD11b⁺Ly6C⁺CD43⁺ macrophages in the spleen and draining lymph nodes of CIA mice. The percentage of CD14⁺CD16⁺ peripheral blood mononuclear cells was reduced by SIN in RA patients. These data indicated that SIN regulates the secretion of multiple inflammatory cytokines and monocyte/macrophage subsets, thereby suppressing RA progression. Therefore, along with MTX, SIN could be an alternative cost-effective anti-inflammatory agent for treating RA.

Azilsartan improves the effects of etanercept in patients with active rheumatoid arthritis: a pilot study

Background and aim

Much evidence has emerged documenting the involvement of the renin-angiotensin system (RAS) in inflammatory processes. The objective of this study was to evaluate the effects of blocking RAS with azilsartan (Azil) on the clinical efficacy of etanercept (Etan) in patients with active rheumatoid arthritis (RA).

Patients and methods

Forty-two patients diagnosed with active RA and poorly responding to methotrexate were enrolled in this pilot clinical study. They were randomly allocated into two groups, and treated with either Etan (50 mg/week) and placebo or the same dose of Etan with Azil (20 mg/day) for 90 days. The clinical outcome was evaluated using the Disease Activity Score-28 joint (DAS-28), simplified disease activity index (SDAI), clinical disease activity index (CDAI) and the health assessment questionnaire disease index (HAQ-DI). Blood samples were obtained for the assessment of C-reactive protein and erythrocyte sedimentation rate at baseline and after 90 days.

Results

The markers of pain and disease activity, C-reactive protein and erythrocyte sedimentation rate were significantly improved when Azil was used, as an adjuvant with Etan, compared with the use of Etan and placebo.

Conclusion

Blocking RAS with azilsartan may improve the effects of etanercept on the clinical markers of pain and disease severity of patients with active RA not responding to methotrexate.

Non-classical monocytes as mediators of tissue destruction in arthritis

Objectives

Bone destruction in rheumatoid arthritis is mediated by osteoclasts (OC), which are derived from precursor cells of the myeloid lineage. The role of the two monocyte subsets, classical monocytes (expressing CD115, Ly6C and CCR2) and non-classical monocytes (which are CD115 positive, but low in Ly6C and CCR2), in serving as precursors for OC in arthritis is still elusive.

Methods

We investigated CCR2^−/− mice, which lack circulating classical monocytes, crossed into hTNFtg mice for the extent of joint damage. We analysed monocyte subsets in hTNFtg and K/BxN serum transfer arthritis by flow cytometry. We sorted monocyte subsets and analysed their potential to differentiate into OC and their transcriptional response in response to RANKL by RNA sequencing. With these data, we performed a gene ontology enrichment analysis and gene set enrichment analysis.

Results

We show that in hTNFtg arthritis local bone erosion and OC generation are even enhanced in the absence of CCR2. We further show the numbers of non-classical monocytes in blood are elevated and are significantly correlated with histological signs of joint destruction. Sorted non-classical monocytes display an increased capacity to differentiate into OCs. This is associated with an increased expression of signal transduction components of RANK, most importantly TRAF6, leading to an increased responsiveness to RANKL.

Conclusion

Therefore, non-classical monocytes are pivotal cells in arthritis tissue damage and a possible target for therapeutically intervention for the prevention of inflammatory joint damage.

mTOR Senses Environmental Cues to Shape the Fibroblast-like Synoviocyte Response to Inflammation

Accumulating evidence suggests that metabolic master regulators, including mTOR, regulate adaptive and innate immune responses. Resident mesenchymal tissue components are increasingly recognized as key effector cells in inflammation. Whether mTOR also controls the inflammatory response in fibroblasts is insufficiently studied. Here, we show that TNF signaling co-opts the mTOR pathway to shift synovial fibroblast (FLS) inflammation toward an IFN response. mTOR pathway activation is associated with decreased NF-κB-mediated gene expression (e.g., PTGS2, IL-6, and IL-8) but increased STAT1-dependent gene expression (e.g., CXCL11 and TNFSF13B). We further demonstrate how metabolic inputs, such as amino acids, impinge on TNF-mTORC1 signaling to differentially regulate pro-inflammatory signaling circuits. Our results define a critical role for mTOR in the regulation of the pro-inflammatory response in FLSs and unfold its pathogenic involvement in TNF-driven diseases, such as rheumatoid arthritis (RA).

The multifaceted link between inflammation and human diseases

Increasing reports on epidemiological, diagnostic, and clinical studies suggest that dysfunction of the inflammatory reaction results in chronic illnesses such as cancer, arthritis, arteriosclerosis, neurological disorders, liver diseases, and renal disorders. Chronic inflammation might progress if injurious agent persists; however, more typically than not, the response is chronic from the start. Distinct to most changes in acute inflammation, chronic inflammation is characterized by the infiltration of damaged tissue by mononuclear cells like macrophages, lymphocytes, and plasma cells, in addition to tissue destruction and attempts to repair. Phagocytes are the key players in the chronic inflammatory response. However, the important drawback is the activation of pathological phagocytes, which might result from continued tissue damage and lead to harmful diseases. The longer the inflammation persists, the greater the chance for the establishment of human diseases. The aim of this review was to focus on advances in the understanding of chronic inflammation and to summarize the impact and involvement of inflammatory agents in certain human diseases.

Repository corticotropin injection as adjunctive therapy in patients with rheumatoid arthritis who have failed previous therapies with at least three different modes of action

Objective

Many types of treatment are available for patients with rheumatoid arthritis (RA), however, some patients fail to achieve remission. This report aims to determine the safety and efficacy of using repository corticotropin injection (RCI) as an adjunctive therapy in patients with RA refractory to at least three therapeutics with different mechanisms of action.

Method

In this open-label, interventional, single-group study, patients received 80 U RCI twice weekly via subcutaneous injection over 12 weeks. Changes in the Ritchie–Camp Articular Index and health assessment questionnaire scores were monitored for changes from baseline measures.

Results

Eight patients were enrolled and consisted of seven females and one male with an average age of 64.6 years and disease duration of 20.9 years. Use of RCI resulted in significant improvement in swollen and tender joint counts. The disease activity score 28 and the physician and patient visual analog scale scores were significantly reduced at treatment week 12. The reduction in health assessment questionnaire scores did not reach statistical significance after RCI treatment. Once RCI therapy was discontinued, all improvements in disease activity score 28, physician and patient visual analog scale, and tender and swollen joint counts achieved during treatment were lost by the week 16 follow-up visit.

Conclusion

While larger clinical trials are necessary to further confirm the efficacy of RCI in patients with refractory RA, the response of patients with refractory RA in this study suggests that RCI can be an effective add-on therapy for patients who have exhausted several classes of treatments. Furthermore, this study suggests that RCI has an alternative mode of action, compared to other available antirheumatic drugs.

MicroRNA-146a governs fibroblast activation and joint pathology in arthritis

Synovial fibroblasts are key cells orchestrating the inflammatory response in arthritis. Here we demonstrate that loss of miR-146a, a key epigenetic regulator of the innate immune response, leads to increased joint destruction in a TNF-driven model of arthritis by specifically regulating the behavior of synovial fibroblasts. Absence of miR-146a in synovial fibroblasts display a highly deregulated gene expression pattern and enhanced proliferation in vitro and in vivo. Deficiency of miR-146a induces deregulation of tumor necrosis factor (TNF) receptor associated factor 6 (TRAF6) in synovial fibroblasts, leading to increased proliferation. In addition, loss of miR-146a shifts the metabolic state of fibroblasts towards glycolysis and augments the ability of synovial fibroblasts to support the generation of osteoclasts by controlling the balance of osteoclastogenic regulatory factors receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG). Bone marrow transplantation experiments confirmed the importance of miR-146a in the radioresistant mesenchymal compartment for the control of arthritis severity, in particular for inflammatory joint destruction. This study therefore identifies microRNA-146a as an important local epigenetic regulator of the inflammatory response in arthritis. It is a central element of an anti-inflammatory feedback loop in resident synovial fibroblasts, who are orchestrating the inflammatory response in chronic arthritis. MiR-146a restricts their activation, thereby preventing excessive tissue damage during arthritis.

Differential inhibition of activity, activation and gene expression of MMP-9 in THP-1 cells by azithromycin and minocycline versus bortezomib: A comparative study

Gelatinase B or matrix metalloproteinase-9 (MMP-9) (EC 3.4.24.35) is increased in inflammatory processes and cancer, and is associated with disease progression. In part, this is due to MMP-9-mediated degradation of extracellular matrix, facilitating influx of leukocytes into inflamed tissues and invasion or metastasis of cancer cells. MMP-9 is produced as proMMP-9 and its propeptide is subsequently removed by other proteases to generate proteolytically active MMP-9. The significance of MMP-9 in pathologies triggered the development of specific inhibitors of this protease. However, clinical trials with synthetic inhibitors of MMPs in the fight against cancer were disappointing. Reports on active compounds which inhibit MMP-9 should be carefully examined in this regard. In a considerable set of recent publications, two antibiotics (minocycline and azythromycin) and the proteasome inhibitor bortezomib, used in cancers, were reported to inhibit MMP-9 at different stages of its expression, activation or activity. The current study was undertaken to compare and to verify the impact of these compounds on MMP-9. With exception of minocycline at high concentrations (>100 μM), the compounds did not affect processing of proMMP-9 into MMP-9, nor did they affect direct MMP-9 gelatinolytic activity. In contrast, azithromycin specifically reduced MMP-9 mRNA and protein levels without affecting NF-κB in endotoxin-challenged monocytic THP-1 cells. Bortezomib, although being highly toxic, had no MMP-9-specific effects but significantly upregulated cyclooxygenase-2 (COX-2) activity and PGE₂ levels. Overall, our study clarified that azithromycin decreased the levels of MMP-9 by reduction of gene and protein expression while minocycline inhibits proteolytic activity at high concentrations.

Anti-arthritic effect of total saponins from Clematis henryi Oliv. on collagen-induced arthritis rats

Background:

As a traditional herbal medicine, Clematis henryi Oliv. has been widely used in China for hundreds of years for the treatment of infectious and inflammatory disorders. Rheumatoid arthritis is a chronic systemic inflammatory disease lacks of effective therapeutic drugs.

Objective:

To investigate the anti-arthritic activity of total saponins extracted from Clematis henryi Oliv. (TSC) and the underlying mechanisms in collagen-induced arthritis (CIA) rats.

Methods:

The purified TSC were administrated to CIA rats at the dose of 150 and 50 mg/kg/d. Paw volume and claw pad thickness were measured every week. The levels of IgG, IL-1β, and TNF-α in serum were measured by ELISA kit, and histopathology of joint was examined by H&E staining.

Results:

Administration of TSC resulted in a significant decrease of paw volume and thickness in CIA rats. TSC also suppressed IgG, IL-1β, and TNF-α levels in serum of CIA rats. Histology revealed that TSC significantly inhibited joint inflammatory cells infiltration and reduced synovial hyperplasia.

Conclusion:

TSC have an anti-arthritic effect on CIA rats, and this effect is probably associated with downregulating the expression of inflammatory factors.

Old and new therapeutics for Rheumatoid Arthritis: in vivo models and drug development

Development of novel drugs for treatment of chronic inflammatory diseases is to a large extent dependent on the availability of good experimental in vivo models in order to perform preclinical tests of new drugs and for the identification of novel drug targets. Here, we review a number of existing rodent models for Rheumatoid Arthritis in the context of how these models have been utilized for developing established therapy in Rheumatoid Arthritis and, furthermore, the present use of animal models for studies of novel drug candidates. We have studied the literature in the field for the use of in vivo models during development of anti-rheumatic drugs; from Methotrexate to various antibody treatments, to novel drugs that are, or have recently been, in clinical trials. For novel drugs, we have explored websites for clinical trials. Although a single Rheumatoid Arthritis in vivo model cannot mirror the complexity of disease development, there exist a number of good animal models for Rheumatoid Arthritis, each defining some parts in disease development, which are useful for studies of drug response. We find that many of the established drugs were not tested in in vivo models before being used in the clinic, but rather animal models have been subsequently used to find mechanisms for efficacy. Finally, we report a number of novel drugs, tested in preclinical in vivo models, presently in clinical trials.

Comparative Pathology of Aging Great Apes: Bonobos, Chimpanzees, Gorillas, and Orangutans

The great apes (chimpanzees, bonobos, gorillas, and orangutans) are our closest relatives. Despite the many similarities, there are significant differences in aging among apes, including the human ape. Common to all are dental attrition, periodontitis, tooth loss, osteopenia, and arthritis, although gout is uniquely human and spondyloarthropathy is more prevalent in apes than humans. Humans are more prone to frailty, sarcopenia, osteoporosis, longevity past reproductive senescence, loss of brain volume, and Alzheimer dementia. Cerebral vascular disease occurs in both humans and apes. Cardiovascular disease mortality increases in aging humans and apes, but coronary atherosclerosis is the most significant type in humans. In captive apes, idiopathic myocardial fibrosis and cardiomyopathy predominate, with arteriosclerosis of intramural coronary arteries. Similar cardiac lesions are occasionally seen in wild apes. Vascular changes in heart and kidneys and aortic dissections in gorillas and bonobos suggest that hypertension may be involved in pathogenesis. Chronic kidney disease is common in elderly humans and some aging apes and is linked with cardiovascular disease in orangutans. Neoplasms common to aging humans and apes include uterine leiomyomas in chimpanzees, but other tumors of elderly humans, such as breast, prostate, lung, and colorectal cancers, are uncommon in apes. Among the apes, chimpanzees have been best studied in laboratory settings, and more comparative research is needed into the pathology of geriatric zoo-housed and wild apes. Increasing longevity of humans and apes makes understanding aging processes and diseases imperative for optimizing quality of life in all the ape species.

IL-17 cytokines in bone healing of diabetic Charcot arthropathy patients: a prospective 2 year follow-up study

Background

Little is currently known of the pathophysiological mechanisms triggering Charcot arthropathy and regulating its recovery although foot trauma has been proposed as a major initiating factor by activation of proinflammatory cytokines leading to increased osteoclastogenic activity and progressive bone destruction. Several members of the IL-17 family of proinflammatory cytokines have been shown to play a key role in the pathogenesis of inflammatory conditions affecting bone and joints but none has previously been studied in Charcot foot patients. The aim of this study was to investigate the role of IL-17A, IL-17E and IL-17F in patients presenting with Charcot foot.

Methods

Twenty-six consecutive Charcot patients were monitored during 2 years by repeated foot radiographs, MRI and circulating levels of IL-17A, IL-17E and IL-17F. Analysis of cytokines was done by ultra-sensitive chemiluminescence technique and data were analyzed by one-way repeated measures ANOVA. Neuropathic diabetic patients (n = 20) and healthy subjects (n = 20) served as controls.

Results

Plasma IL-17A and IL-17E in weight-bearing Charcot patients at diagnosis were at the level of diabetic controls, whereas IL-17F was significantly lower than diabetic controls. A significant increase in IL-17A and IL-17E reaching a peak 2–4 months after inclusion and start of offloading treatment in Charcot patients was followed by a gradual decrease to the level of diabetic controls at 2 years postinclusion. In contrast, IL-17F increased gradually from inclusion to a level not significantly different from diabetic controls after 2 years.

Conclusions

Charcot patients display a significant elevation of all three IL-17 cytokines during the follow-up period relative values at diagnosis and values in control patients supporting a role in the bone repair and remodeling activity during the recovery phase. The rapid increase of IL-17A and IL-17E shortly after initiating off-loading treatment could suggest this to be a response to immobilization and stabilization of the diseased foot.

Structural integrity versus radiographic progression in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic, progressive and inflammatory disease often leading to irreversible destruction of articular structures and consequent disability. The key steps of RA pathogenetic mechanisms are the break of immune tolerance and the production of autoantibodies, followed by systemic and local inflammation resulting in damage of both subchondral bone (erosion) and cartilage (joint space narrowing (JSN)). Evidences from clinical trials suggest that erosions and JSN are the result of inter-related but partly independent pathogenetic pathways, in both cases mediated by pro-inflammatory cytokines, even if a direct effect of cyclic citrullinated peptides (anticitrullinated protein antibodies, ACPAs) on bone damage had been postulated. As a consequence, the suppression of inflammation provided by synthetic and biological disease-modifying antirheumatic drugs results in a decreased progression of bone and cartilage damage, supporting the effectiveness of the treat-to-target strategy. Nevertheless, radiographic progression may also be detected in patients achieving a sustained clinical remission. Two main reasons for this apparent uncoupling between clinical synovitis and damage progression should be considered. First, in some cases, the use of composite indices to define remission may not be completely adequate to identify residual disease activity, requiring the concomitant introduction of more sensible tools such as imaging. Second, the direct effect of biological drugs on bone destruction inducers, such as pro-inflammatory cytokines, may explain the suppression of radiographic progression despite the persistence of clinical synovitis. In this review, we discuss the link between autoimmunity, inflammation, joint damage and disability, focusing on how radiographic progression may predict functional disability.

Eicosapentaenoic acid and docosapentaenoic acid monoglycerides are more potent than docosahexaenoic acid monoglyceride to resolve inflammation in a rheumatoid arthritis model

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease of the joints and bones. Omega-3 (ω3) fatty acid supplementation has been associated with a decreased production of inflammatory cytokines and eicosanoids involved in RA pathogenesis. The aim of this study was to determine the therapeutic potential of ω3 monoglyceride (MAG-ω3) compounds in an in vivo rat model of RA induced by Complete Freund's Adjuvant (CFA).

METHOD

CFA rats were untreated or treated per os with three specific compounds, namely, MAG-docosahexaenoic acid (MAG-DHA), MAG-eicosapentaenoic acid (MAG-EPA) and MAG-docosapentaenoic acid (MAG-DPA). Morphological and histological analyses, as well as pro-inflammatory marker levels were determined following MAG-ω3 treatments.

RESULTS

Morphological and histological analyses revealed that MAG-EPA and MAG-DPA exhibited strong activity in reducing the progression and severity of arthritic disease in CFA rats. Following MAG-EPA and MAG-DPA treatments, plasma levels of the pro-inflammatory cytokines; interleukin 17A (IL-17A), IL-1β, IL-6 and tumor necrosis factor α (TNFα) were markedly lower when compared to CFA-untreated rats. Results also revealed a decreased activation of p38 mitogen-activated protein kinases (p38 MAPK) and nuclear factor-kappa B (NFκB) pathways correlated with a reduced expression of TNFα, cyclooxygenase-2 (COX-2), matrix metalloproteinase-2 (MMP-2) and MMP-9 in paw homogenates derived from MAG-EPA and MAG-DPA-treated rats. Of interest, the combined treatment of MAG-EPA and vitamin E displayed an antagonistic effect on anti-inflammatory properties of MAG-EPA in CFA rats.

CONCLUSION

Altogether, the present data suggest that MAG-EPA, without vitamin E, represents a new potential therapeutic strategy for resolving inflammation in arthritis.

Inhibition of small HA fragment activity and stimulation of A2A adenosine receptor pathway limit apoptosis and reduce cartilage damage in experimental arthritis

Recent studies have found that the inactivation of small hyaluronan (HA) fragments originating from native HA during inflammation reduced the inflammatory response in models of experimental arthritis. The stimulation of adenosine receptors A2A reduced inflammation by inhibiting NF-kB activation. The combination of both treatments was significantly more effective than either of the individual treatments. The aim of this study was to further investigate the effects of a combined treatment using the HA inhibitor Pep-1 and a selective A2AR agonist (CV-1808) on the structure and ultrastructure of the articular cartilage and on apoptosis in a model of collagen-induced arthritis (CIA) in mice. Arthritic mice were treated with Pep-1 and/or CV-1808 intraperitoneally daily for 20 days. At day 35, the hind limbs were processed for light microscopy (hematoxylin/eosin and Safranin-O-Fast Green) and for transmission and scanning electron microscopy. CIA increased IL-6, caspase-3 and caspase-7 mRNA expression and the related protein levels in arthritic articular cartilage, and significantly increased concentrations of Bcl-2-associated X protein (Bax), while B cell-lymphoma-2 protein (Bcl-2) was markedly reduced. The combined Pep-1/CV-1808 treatment significantly reduced CIA injury, particularly at the highest doses, demonstrated by the presence of Safranin-O-positive cartilage, with a smooth surface and normal chondrocytes in the superficial, intermediate and deep zones. Morphological data and histological scoring were strongly supported by the reduction in inflammation and apoptotic markers. The results further support the role of HA degradation and A2A receptors in arthritis.