Murine Model Of Rheumatoid Arthritis Research Articles

Regulation of neutrophil associated RNASET2 expression in rheumatoid arthritis

Neutrophils (PMNs) are key players of innate immune responses through the release of cytoplasmic granule content and the formation of neutrophil extracellular traps (NETs). RNASET2 is an acidic ribonuclease, recently proposed as an alarmin signal associated with inflammatory responses. Here we show that, along the neutrophil maturation cascade, RNASET2 is expressed in segmented and mature PMNs. In human PMNs, RNASET2 colocalized with primary and tertiary granules and was found to be associated with NETs following PMA or Nigericin stimulation. Similarly, activation of PMNs by soluble immune complexes, a hallmark of several autoimmune diseases, also induced RNASET2-associated NETs. Genome-wide association studies recently identified RNASET2 among a cluster of genes associated with increased susceptibility to develop autoimmune diseases, including rheumatoid arthritis (RA). RNASET2 was found expressed by PMNs and macrophages infiltrating inflamed joints in a murine model of RA (K/BxN Serum-Transfer-Induced Arthritis, STIA), by immunostaining. Similar results were found in synovial biopsies of RA patients with active disease. In addition, we demonstrate that RNASET2 circulating levels correlated with the onset and the severity of disease in two mouse models of inflammatory arthritis, STIA and CIA (Collagen-Induced Arthritis) and in serum of RA patients. These results show that PMNs are an important source of RNASET2 and that its circulating levels are associated with RA development suggesting a role for RNASET2 in the pathogenesis of immune-mediated diseases.

Increased imaging ligand hydrophilicity and improved pharmacokinetic properties provides enhanced in vivo targeting of fibroblast activation protein

In this work, the impact of physicochemical modifications on pharmacokinetics and in vivo targeting of a small molecule fibroblast activation protein inhibitor (FAPI) imaging ligand in a murine model of rheumatoid arthritis was evaluated. While similar ligands have been well-reported in oncology for molecular imaging and radiotherapy, there are limited reports of FAPI derivatives in targeted applications in immunology. As inflammation may increase both specific and non-specific delivery of targeted agents in general, we sought to identify the optimal targeted molecular imaging probe characteristics for efficient cell surface engagement. A series of FAPI derivatives were synthesized and their physicochemical properties modified via conjugation of fluorescent dyes and/or an albumin-binding small molecule. The impact of these modifications on cell surface binding affinity was assessed using an overexpressing cell line. Additionally, a thorough mechanistic characterization of fibroblast activation protein (FAP) cell surface internalization was evaluated in both overexpressing and endogenously expressing cells. Lastly, the pharmacokinetics and in vivo uptake in inflamed arthritic paws were characterized via near-infrared (NIR) imaging. All targeted molecular imaging agents tested maintained strong nanomolar binding affinity to cell surface FAP independent of chemical modification. The murine fibroblast-like synoviocytes expressed lower absolute cell-surface FAP compared to a transfected line, and the net internalization half-life measured for the transfected cells via flow cytometry was 7.2 h. The unmodified FAPI ligand exhibited the poorest in vivo targeting, likely resulting from its large apparent volume of distribution (62.7 ml) and rapid systemic clearance (t1/2 = 0.5 h). Conjugation of a charged, hydrophilic AF647 fluorophore decreased systemic clearance (t1/2 = 2.1 h) and demonstrated a 2-fold improvement in blocking FAPI-800CW engagement of FAP in vivo when compared to blocking of FAPI-800CW with FAPI with up to 2.8-fold improvements noted for the equivalent albumin binding construct comparison.

Inhibition of the TIM-1 and -3 signaling pathway ameliorates disease in a murine model of rheumatoid arthritis.

Members of the T-cell immunoglobulin and mucin (TIM) family, which is crucial for T-cell function, are implicated in autoimmunity. TIM-1 and -3 play distinct roles in autoimmunity, with TIM-1 acting as a costimulatory molecule and TIM-3 regulating Th1 responses. We investigated the therapeutic potential of anti-TIM-1 (RMT1-10) and anti-TIM-3 (RMT3-23) antibodies in an autoimmune arthritis model. Zymosan A was used to induce arthritis in female SKG mice. The arthritis scores, histology, mRNA expression, cytokine levels, micro-computed tomography, and flow cytometry results were obtained. The application of RMT1-10 reduced the arthritis scores, histological damage, and CD4+ T-cell infiltrations, and it suppressed interleukin (IL)-6 and -17A and reduced TIM-3 mRNA expressions. RMT3-23 also lowered arthritis severity, improved histology, and reduced serum levels of tumor necrosis factor (TNF)-α and IL-17A. RMT3-23 inhibited intracellular TNF-α and IL-6 and early apoptosis. An amelioration of autoimmune arthritis was achieved by blocking the TIM-1 and -3 signaling pathways via RMT1-10 and RMT3-23 administration, leading to a widespread decrease in inflammatory cytokines. Both antibodies exhibited therapeutic effects, suggesting TIM-1 and -3 as potential targets for rheumatoid arthritis.

Carbon monoxide (CO)-releasing micelles enable efficient treatment of MRSA-induced septic arthritis and rheumatoid arthritis

Septic arthritis (SA) and rheumatoid arthritis (RA) are prevalent and challenging joint diseases that often lead to severe consequences, including sepsis, disability, and life-threatening conditions. However, their distinct etiologies and pathological mechanisms require different treatment strategies. We herein report a single formulation of carbon monoxide (CO)-releasing micelles capable of efficient treatment of both SA and RA diseases. Our findings demonstrate that the local release of CO under red light stimulus effectively eradicates methicillin-resistant Staphylococcus aureus (MRSA) pathogens while safeguarding MRSA-infected chondrocytes and osteogenic cells. Furthermore, CO delivery orchestrates macrophage polarization homeostasis via the nuclear factor erythroid-2-related factor (Nrf2)/heme oxygenase-1 (HO-1) pathway, manifesting unique anti-inflammatory and anti-osteoclastic effects. These remarkable properties empower CO-releasing micelles to emerge as a singular treatment approach, addressing both SA and RA in murine models without the need for conventional medications such as antibiotics and nonsteroidal anti-inflammatory drugs (NSAIDs).

Ethanol Extract of Caryota urens Lour Fruits Alleviates Oxidative Stress in a Murine Model of Rheumatoid Arthritis Induced by Freund's Complete Adjuvant

Ethanol Extract of Caryota urens Lour Fruits Alleviates Oxidative Stress in a Murine Model of Rheumatoid Arthritis Induced by Freund's Complete Adjuvant

Extracorporeal photopheresis reduces inflammation and joint damage in a rheumatoid arthritis murine model

BackgroundRheumatoid arthritis (RA) is an autoimmune disease characterized by inflammatory reactions and tissue damage in the joints. Long-term drug use in clinical practice is often accompanied by adverse reactions. Extracorporeal photopheresis (ECP) is an immunomodulatory therapy with few side effects, offering a potential and safe therapeutic alternative for RA through the induction of immune tolerance. This study aimed to investigate the therapeutic effects of ECP on RA using a collagen-induced arthritis (CIA) murine model, as well as to explore its immunomodulatory effects in vivo. Additionally, particular attention was given to the significant role of monocytes during the ECP process.MethodsA murine model of rheumatoid arthritis was established by administering two injections of bovine type II collagen to DBA/1J mice. ECP, ECP-MD (mononuclear cells were depleted during the ECP), MTX, and PBS treatment were applied to the CIA mice. During the treatment process, clinical scores and body weight changes of CIA mice were closely monitored. After six treatment sessions, micro-CT images of the hind paws from live mice were captured. Ankle joints and paws of the mice were collected and processed for histological evaluation. Spleen samples were collected to measure the Th17/Treg cells ratio, and serum samples were collected to assess cytokine and anti-type II collagen IgG levels. Monocytes and dendritic cells populations before and after ECP in vitro were detected by flow cytometry.ResultECP therapy significantly attenuated the progression of CIA, alleviated the severity of clinical symptoms in CIA mice and effectively suppressed synovial hyperplasia, inflammation, and cartilage damage. There was an expansion in the percentage of CD3 + CD4 + CD25 + FoxP3 + Tregs and a decrease in CD3 + CD4 + IL17A + Th17 cells in vivo. Furthermore, ECP reduced the serum levels of pro-inflammatory cytokines IL-6 (53.47 ± 7.074 pg/mL vs 5.142 ± 1.779 pg/mL, P < 0.05) and IL-17A (3.077 ± 0.401 pg/mL vs 0.238 ± 0.082 pg/mlL, P < 0.0001) compared with PBS. Interestingly, the depletion of monocytes during the ECP process did not lead to any improvement in clinical symptoms or histological scores in CIA mice. Moreover, the imbalance in the Th17/Treg cells ratio became even more pronounced, accompanied by an augmented secretion of pro-inflammatory cytokines IL-6 and IL-17A. In vitro, compared with cells without ECP treatment, the proportion of CD11b + cells were significantly reduced (P < 0.01), the proportion of CD11c + cells were significantly elevated (P < 0.001) 24 h after ECP treatment. Additionally, the expression of MHC II (P < 0.0001), CD80 (P < 0.01), and CD86 (P < 0.001) was downregulated in CD11c + cells 24 h after ECP treatment.ConclusionOur study demonstrates that ECP exhibits a therapeutic effect comparable to conventional therapy in CIA mice, and the protective mechanisms of ECP against RA involve Th17/Treg cells ratio, which result in decreased IL-6 and IL-17A. Notably, monocytes derived from CIA mice are an indispensable part to the efficacy of ECP treatment, and the proportion of monocytes decreased and the proportion of tolerogenic dendritic cells increased after ECP treatment in vitro.

Liposomal AntagomiR-155-5p Restores Anti-Inflammatory Macrophages and Improves Arthritis in Preclinical Models of Rheumatoid Arthritis.

We previously reported an increased expression of microRNA-155 (miR-155) in the blood monocytes of patients with rheumatoid arthritis (RA) that could be responsible for impaired monocyte polarization to anti-inflammatory M2-like macrophages. In this study, we employed two preclinical models of RA, collagen-induced arthritis and K/BxN serum transfer arthritis, to examine the therapeutic potential of antagomiR-155-5p entrapped within PEGylated (polyethylene glycol [PEG]) liposomes in resolution of arthritis and repolarization of monocytes towards the anti-inflammatory M2 phenotype. AntagomiR-155-5p or antagomiR-control were encapsulated in PEG liposomes of 100 nm in size and -10 mV in zeta potential with high antagomiR loading efficiency (above 80%). Mice were injected intravenously with 1.5 nmol/100 μL PEG liposomes containing antagomiR-155-5p or control after the induction of arthritis. We demonstrated the biodistribution of fluorescently tagged PEG liposomes to inflamed joints one hour after the injection of fluorescently tagged PEG liposomes, as well as the liver's subsequent accumulation after 48 hours, indicative of hepatic clearance, in mice with arthritis. The injection of PEG liposomes containing antagomiR-155-5p decreased arthritis score and paw swelling compared with PEG liposomes containing antagomiR-control or the systemic delivery of free antagomiR-155-5p. Moreover, treatment with PEG liposomes containing antagomiR-155-5p led to the restoration of bone marrow monocyte defects in anti-inflammatory macrophage differentiation without any significant functional change in other immune cells, including splenic B and T cells. The injection of antagomiR-155-5p encapsulated in PEG liposomes allows the delivery of small RNA to monocytes and macrophages and reduces joint inflammation in murine models of RA, providing a promising strategy in human disease.

Pharmacological profiles and clinical efficacy of ozoralizumab (Nanozora® 30 ‍mg Syringes for S.C. Injection), the first Nanobody® compound in Japan

Ozoralizumab, a novel TNF inhibitor, is the first NANOBODY® compound in Japan for rheumatoid arthritis. This compound consists of a humanized fusion protein with a trimeric structure having two anti-human TNFα NANOBODY® molecules and one anti-human serum albumin NANOBODY® molecule, and has the unique structure without an Fc portion. Ozoralizumab showed an inhibitory effect on TNFα-induced cell death, and its inhibitory concentration was lower than that of etanercept, adalimumab, and infliximab. Ozoralizumab also showed inhibitory effects on human TNFα-induced cellular infiltration in the murine air pouch model and reduced the arthritis scores in a murine rheumatoid arthritis model. In addition, ozoralizumab showed distinctive pharmacological characteristics different from the traditional IgG antibodies, which may be attributed to its unique structure, such as its ability to rapidly distribute to inflamed joint tissues in a murine rheumatoid arthritis model, and its immune complexes with TNFα do not induce inflammation in a murine subcutaneous inflammation model. In clinical trials, ozoralizumab demonstrated clinical efficacy in rheumatoid arthritis patients with inadequate response to methotrexate, which was observed from day 3 of treatment. Ozolalizumab also showed improvements in clinical symptoms in rheumatoid arthritis patients without methotrexate. The safety profile of the compound was not significantly different from that of current TNF inhibitors. Based on these results, ozoralizumab was approved in September 2022. Ozoralizumab shows early improvement of clinical symptoms in patients with rheumatoid arthritis, and its characteristic structure is expected to be new treatment options for patients who have an inadequate response to current bDMARDs.

Genetically Engineered Membrane‐Coated Nanoparticles as Versatile Platforms with Reduced Protein Corona for Targeted siRNA Delivery

AbstractLow uptake efficiency in vivo as well as systemic toxicities of nucleic‐acid nanovehicles substantially retard the clinical translation of gene therapy. Targeted gene delivery to specific cell populations with antibody display techniques and membrane‐coated nanoparticle (NP) approaches may solve these problems. Here, a new class of targeted membrane‐camouflaged nanosystem is successfully constructed, which is made of polydopamine (PDA) nanoparticles coated with biosynthetic antibody‐displaying membranes from stem cells. In murine models of rheumatoid arthritis and colitis, the membrane‐camouflaged nanocarriers displayed anti‐CD64 antibodies in a ligand‐oriented way via the biosynthetic method and has reduced protein corona due to the coating of the negatively charged cell membrane, thereby achieving remarkable therapeutic efficacy through silencing the TNF expression selectively in CD64‐positive immune cell subsets. By expressing a wide variety of functional protein ligands on the cellular membranes that are further coated onto PDA nanoparticles, the membrane‐camouflaged nanosystems can also serve as a versatile theranostic platform that enables antibody‐targeted gene/siRNA delivery to the cells of interest in vivo, especially immune cells.

OA21 Are novel anti-IL5 biologics triggering rheumatoid arthritis?

Abstract Introduction Biologics are being increasingly used for the treatment of inflammatory diseases across a wide range of specialties. Of particular interest, it is well established that monoclonal therapy for one inflammatory disease may paradoxically trigger another inflammatory disease, for example TNF therapy triggering multiple sclerosis, and IL-17 therapy for psoriasis linked to inflammatory bowel disease. Here we report the case of a patient who developed anti-CCP positive rheumatoid arthritis soon after starting a novel anti-IL-5 biologic used to treat his severe eosinophilic asthma. Case description This 77-year-old gentleman with a background of severe eosinophilic asthma presented to our early arthritis clinic 18 months after having been started on either mepolizumab or a long-acting IL-5 blocker as part of a clinical trial. Prior to starting biologics, his asthma had been poorly controlled with salbutamol, Fostair, tiotropium inhalers and low-dose corticosteroids. Within weeks, he developed symmetrical arthralgias involving small joints, particularly his wrists and knuckles, as well as significant early morning stiffness lasting more than one hour. On examination, he had clinical synovitis in the wrists and metacarpophalangeal joints bilaterally, as well as right shoulder capsulitis with limiting range of motion. Blood tests revealed a raised CRP of 24mg/L, WCC 8.77 10*9/L, rheumatoid factor of 263.2 iu/mL and anti-CCP antibody of &amp;gt; 300 U/mL. Ultrasound imaging of the hands and wrists bilaterally showed grade II grey scale with grade II power Doppler, and some erosions in the wrists bilaterally. There was hypoechogenicity of the left extensor carpi ulnaris tendon with some associated grey scale and power Doppler. He was diagnosed with rheumatoid arthritis as per the American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) diagnostic criteria and started on prednisolone 10mg daily as a rescue therapy to reduce the inflammation, followed by sulfasalazine one month later as the disease modifying agent. He was followed-up in rheumatology clinic two months later and showed significant improvements: the pains and swellings of his joints had settled, and whilst he still gets early morning stiffness this is not so debilitating. His inflammatory markers had also resolved with CRP &amp;lt;5.0mg/L and WCC 9.31 10*9/L. Discussion We report a case of new onset rheumatoid arthritis associated with the commencement of an anti-IL-5 biologics for severe asthma. To our knowledge, this has only been reported in the literature on a handful of occasions and in each case the patients were on oral corticosteroids with the majority being weaned off in parallel to developing the new symptoms [1,2]. As such there has been a challenge in associating the development of arthritis with the initiation of the anti-IL-5 biologic, as opposed to the withdrawal of steroids unmasking a pre-existing disease. Emerging evidence has implicated a core role for regulatory eosinophils (rEos) in the resolution of rheumatoid arthritis (RA) [3]. In murine models of RA, an expansion of rEos in the synovium was sufficient to bring about remission of arthritis. Inhibiting the IL-5 pathway would subsequently induce relapse of the arthritis [3]. Further studies are required to characterise the significance of these findings in clinical cohorts and to identify whether there is an actual association between novel anti-IL-5 biologics and rheumatoid arthritis. Key learning points Our improved understanding of the mechanisms underlying inflammatory diseases has led to the increased use of biological therapies in treating these conditions. However, these therapies may be paradoxically triggering other inflammatory diseases, particularly autoimmune rheumatological diseases. Here we have identified a patient who developed anti-CCP positive rheumatoid arthritis soon after commencing a novel anti-IL5 for severe asthma. Mechanistically, this may be related to the depletion of regulatory eosinophils tipping the balance towards pro-inflammatory pathways in the synovial joints. More work is required to identify whether this phenomenon is being more widely observed in clinical practice, and if so how we can best manage it going forwards.

Dysregulation of B lymphocyte development in the SKG mouse model of rheumatoid arthritis.

Rheumatoid arthritis is a chronic and systemic inflammatory disease that affects approximately 1% of the world's population and is characterised by joint inflammation, the destruction of articular cartilage and bone, and many potentially life-threatening extraarticular manifestations. B lymphocytes play a central role in the pathology of rheumatoid arthritis as the precursors of autoantibody secreting plasma cells, as highly potent antigen-presenting cells, and as a source of various inflammatory cytokines, however, the effects of rheumatoid arthritis on B lymphocyte development remain poorly understood. Here, we analyse B lymphocyte development in murine models of rheumatoid arthritis, quantifying all the subsets of B cell precursors in the bone marrow and splenic B cells using flow cytometry. We demonstrate a severe reduction in pre-B cells and immature B cells in the bone marrow of mice with active disease, despite no major effects on the mature naïve B cell numbers. The loss of B cell precursors in the bone marrow of the affected mice was associated with a highly significant reduction in the proportion of Ki67+ cells, indicating impaired cell proliferation, while the viability of the B cell precursors was not significantly affected. We also observed some mobilisation of the B cell precursor cells into the mouse spleen, demonstrated with flow cytometry and pre-B colony forming units assays. In summary, the current work demonstrates a severe dysregulation in B lymphocyte development in murine rheumatoid arthritis, with possible implications for B cell repertoire formation, tolerance induction, and disease mechanisms.

Anti-arthritic efficacy of Bombax ceiba ethanolic extract in a murine model for rheumatoid arthritis using in vivo, in vitro and radiological analysis.

Rheumatoid arthritis (RA) is a multisystem autoimmune disease that causes discomfort, synovial membrane inflammation, peripheral joint inflammation, morning stiffness, articular tissue loss, and restricted joint movement. In the present study, we aim to explore the anti-arthritic efficacy of Bombax ceiba ethanolic extract in a Freund's Complete Adjuvant-induced arthritis, in murine model. The hot soxhlet method was used to extract dried aerial components of Bombax ceiba using an ethyl alcohol: water (70:30) ratio. Bombax ceiba ethanolic extract at two doses of 200 and 400 mg/kg was investigated in Wistar rats against Freund's full adjuvant-induced chronic immunological arthritis. Anti-arthritis efficacy was studied utilising morphological research (paw volume, paw diameter, and body weight). On the 28th day, the animals were sacrificed, and haematological parameters, pro-inflammatory cytokines (TNF-alpha, IL-6), cell culture, histological and radiological analysis were performed. BCEE inhibited paw oedema significantly (P 0.05) at a dose of 40mg/Kg, which was corroborated by paw volume and diameter, as well as haematological parameters, in Freund's complete adjuvant-induced arthritis model. The BCEE also significantly reduced pro-inflammatory cytokine levels and the histopathological changes caused by Freund's full adjuvant model. BCEE preserves synovial membranes by enhancing health and has shown a significant anti-arthritic activity. Thus, data confirms the traditional usage of Bombax ceiba for arthritis.

GCSB-5 regulates inflammatory arthritis and pain by modulating the mitogen-activated protein kinase signaling pathway in a murine model of rheumatoid arthritis.

This study aimed to determine whether GCSB-5 has anti-inflammatory and antinociceptive effects in mice with collagen-induced arthritis (CIA), an animal model of rheumatoid arthritis (RA), and investigate the influence of GCSB-5 on the mitogen-activated protein kinase (MAPK) pathway. The experimental animal study was designed to include five groups: CIA mice treated with GCSB-5 (300 mg/kg), GCSB-5 (600 mg/kg), celecoxib (60 mg/kg), or saline for four weeks, and nontreated control mice. The clinical severity of arthritis was scored. Nociceptive thresholds were measured by using a von Frey dynamic plantar analgesimeter. The MAPK pathway was evaluated in mouse synovium. The expression of channels associated with pain signaling was assessed by western blot and immunohistochemical staining. GCSB-5 treatment diminished the severity of clinical arthritis and increased the nociceptive threshold in mice with CIA. Celecoxib, a positive control drug, also showed comparable changes. Clinical arthritis scores were inversely related to mechanical thresholds. GCSB-5 administration decreased the levels of anti-type II collagen antibody and inflammatory cytokines in the sera of mice with CIA. Furthermore, ERK, p38 MAPK, and JNK phosphorylation were downregulated and TRPV1 and ASIC3 expression were decreased in the synovium of GCSB-5-treated mice compared to salinetreated mice. Interleukin-6-induced TRPV1 and ASIC3 upregulation were also inhibited by GCSB-5 in human RA fibroblast-like synoviocytes in vitro. GCSB-5 decreased inflammatory arthritis and pain in a murine model of RA. The results present evidence that GCSB-5 may be beneficial for relieving pain as well as decreasing inflammation in autoimmune arthritis, such as RA.

Citrullination is linked to reduced Ca2+ sensitivity in hearts of a murine model of rheumatoid arthritis.

Cardiac contractile dysfunction is prevalent in rheumatoid arthritis (RA), with an increased risk for heart failure. A hallmark of RA has increased levels of peptidyl arginine deaminases (PAD) that convert arginine to citrulline leading to ubiquitous citrullination, including in the heart. We aimed to investigate whether PAD-dependent citrullination in the heart was linked to contractile function in a mouse model of RA during the acute inflammatory phase. We used hearts from the collagen-induced arthritis (CIA) mice, with overt arthritis, and control mice to analyze cardiomyocyte Ca2+ handling and fractional shortening, the force-Ca2+ relationship in isolated myofibrils, the levels of PAD, protein post-translational modifications, and Ca2+ handling protein. Then, we used an in vitro model to investigate the role of TNF-α in the PAD-mediated citrullination of proteins in cardiomyocytes. Cardiomyocytes from CIA mice displayed larger Ca2+ transients than controls, whereas cell shortening was similar in the two groups. Myofibrils from CIA hearts required higher [Ca2+ ] to reach 50% of maximum shortening, ie Ca2+ sensitivity was lower. This was associated with increased PAD2 expression and α-actin citrullination. TNF-α increased PAD-mediated citrullination which was blocked by pre-treatment with the PAD inhibitor 2-chloroacetamide. Using a mouse RA model we found evidence of impaired cardiac contractile function linked to reduced Ca2+ sensitivity, increased expression of PAD2, and citrullination of α-actin, which was triggered by TNF-α. This provides molecular and physiological evidence for acquired cardiomyopathy and a potential mechanism for RA-associated heart failure.

Tonsillar Microbiome-Derived Lantibiotics Induce Structural Changes of IL-6 and IL-21 Receptors and Modulate Host Immunity.

Emerging evidence emphasizes the functional impacts of host microbiome on the etiopathogenesis of autoimmune diseases, including rheumatoid arthritis (RA). However, there are limited mechanistic insights into the contribution of microbial biomolecules especially microbial peptides toward modulating immune homeostasis. Here, by mining the metagenomics data of tonsillar microbiome, a deficiency of the encoding genes of lantibiotic peptides salivaricins in RA patients is identified, which shows strong correlation with circulating immune cells. Evidence is provided that the salivaricins exert immunomodulatory effects in inhibiting T follicular helper (Tfh) cell differentiation and interleukin‐21 (IL‐21) production. Mechanically, salivaricins directly bind to and induce conformational changes of IL‐6 and IL‐21 receptors, thereby inhibiting the bindings of IL‐6 and IL‐21 to their receptors and suppressing the downstream signaling pathway. Finally, salivaricin administration exerts both prophylactic and therapeutic effects against experimental arthritis in a murine model of RA. Together, these results provide a mechanism link of microbial peptides‐mediated immunomodulation.

Single-cell multimodal analysis identifies common regulatory programs in synovial fibroblasts of rheumatoid arthritis patients and modeled TNF-driven arthritis

BackgroundSynovial fibroblasts (SFs) are specialized cells of the synovium that provide nutrients and lubricants for the proper function of diarthrodial joints. Recent evidence appreciates the contribution of SF heterogeneity in arthritic pathologies. However, the normal SF profiles and the molecular networks that govern the transition from homeostatic to arthritic SF heterogeneity remain poorly defined.MethodsWe applied a combined analysis of single-cell (sc) transcriptomes and epigenomes (scRNA-seq and scATAC-seq) to SFs derived from naïve and hTNFtg mice (mice that overexpress human TNF, a murine model for rheumatoid arthritis), by employing the Seurat and ArchR packages. To identify the cellular differentiation lineages, we conducted velocity and trajectory analysis by combining state-of-the-art algorithms including scVelo, Slingshot, and PAGA. We integrated the transcriptomic and epigenomic data to infer gene regulatory networks using ArchR and custom-implemented algorithms. We performed a canonical correlation analysis-based integration of murine data with publicly available datasets from SFs of rheumatoid arthritis patients and sought to identify conserved gene regulatory networks by utilizing the SCENIC algorithm in the human arthritic scRNA-seq atlas.ResultsBy comparing SFs from healthy and hTNFtg mice, we revealed seven homeostatic and two disease-specific subsets of SFs. In healthy synovium, SFs function towards chondro- and osteogenesis, tissue repair, and immune surveillance. The development of arthritis leads to shrinkage of homeostatic SFs and favors the emergence of SF profiles marked by Dkk3 and Lrrc15 expression, functioning towards enhanced inflammatory responses and matrix catabolic processes. Lineage inference analysis indicated that specific Thy1+ SFs at the root of trajectories lead to the intermediate Thy1+/Dkk3+/Lrrc15+ SF states and culminate in a destructive and inflammatory Thy1− SF identity. We further uncovered epigenetically primed gene programs driving the expansion of these arthritic SFs, regulated by NFkB and new candidates, such as Runx1. Cross-species analysis of human/mouse arthritic SF data determined conserved regulatory and transcriptional networks.ConclusionsWe revealed a dynamic SF landscape from health to arthritis providing a functional genomic blueprint to understand the joint pathophysiology and highlight the fibroblast-oriented therapeutic targets for combating chronic inflammatory and destructive arthritic disease.

HYDROQUINONE,A CIGARETTE SMOKE COMPOUND, AFFECTS CARTILAGE HOMEOSTASISTHROUGHACTIVATION OF THE ARYL HYDROCARBON RECEPTOR PATHWAY

Purpose: Exposure to cigarette smoke has a proven detrimental impact on different aspects of human health. Increasing evidence linked smoking to degeneration of joint tissues. However, the toxic mechanisms elicited by the different components of cigarette smoke have not been fully understood. We have previously shown that exposure to hydroquinone (HQ), a pro-oxidative chemical present in cigarette smoke, can promote joint tissue degradation in murine models of rheumatoid arthritis through the activation of the aryl hydrocarbon receptor (AhR) pathway.

Effects of aerobic and resistance exercise in murine models of rheumatoid arthritis and osteoarthritis – a systematic review

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Peptidylarginine Deiminase 2 in Murine Antiviral and Autoimmune Antibody Responses.

The peptidylarginine deiminases (PADs) and the citrullinated proteins that they generate have key roles in innate immunity and rheumatoid arthritis, an inflammatory arthritis with antibodies that target citrullinated proteins. However, the importance of PADs, particularly PAD2, in the adaptive immune response, both normal and pathogenic, is newly emerging. In this study, we evaluated a requirement for PAD2 in the antibody response in collagen-induced arthritis (CIA), a T and B cell-driven murine model of rheumatoid arthritis, and in the protective antibody response to murine influenza infection. Using PAD2−/− and PAD2+/+ mice on the DBA/1J background, we found that PAD2 is required for maximal anti-collagen antibody levels, but not collagen-specific plasma cell numbers, T cell activation or polarization, or arthritis severity in CIA. Also, we found that PAD2 is required not just for normal levels of persistent hemagglutination inhibiting antibodies but also for full protection from lethal influenza rechallenge. Together, these data provide evidence for a novel modest requirement for PAD2 in a normal antiviral antibody response and in an abnormal autoantibody response in inflammatory arthritis.

Improving dexamethasone drug loading and efficacy in treating arthritis through a lipophilic prodrug entrapped into PLGA-PEG nanoparticles.

Targeted delivery of dexamethasone to inflamed tissues using nanoparticles is much-needed to improve its efficacy while reducing side effects. To drastically improve dexamethasone loading and prevent burst release once injected intravenously, a lipophilic prodrug dexamethasone palmitate (DXP) was encapsulated into poly(DL-lactide-co-glycolide)-polyethylene glycol (PLGA-PEG) nanoparticles (NPs). DXP-loaded PLGA-PEG NPs (DXP-NPs) of about 150 nm with a drug loading as high as 7.5% exhibited low hemolytic profile and cytotoxicity. DXP-NPs were able to inhibit the LPS-induced release of inflammatory cytokines in macrophages. After an intravenous injection to mice, dexamethasone (DXM) pharmacokinetic profile was also significantly improved. The concentration of DXM in the plasma of healthy mice remained high up to 18 h, much longer than the commercial soluble drug dexamethasone phosphate (DSP). Biodistribution studies showed lower DXM concentrations in the liver, kidneys, and lungs when DXP-NPs were administered as compared with the soluble drug. Histology analysis revealed an improvement in the knee structure and reduction of cell infiltration in animals treated with the encapsulated DXP compared with the soluble DSP or non-treated animals. In summary, the encapsulation of a lipidic prodrug of dexamethasone into PLGA-PEG NPs appears as a promising strategy to improve the pharmacological profile and reduce joint inflammation in a murine model of rheumatoid arthritis.Graphical abstract Supplementary informationThe online version contains supplementary material available at 10.1007/s13346-021-01112-3.