Extracellular Vesicles Transfer the Receptor Programmed Death-1 in Rheumatoid Arthritis

Extracellular vesicles: immunomodulation, diagnosis, and promising therapeutic roles for rheumatoid arthritis

Extracellular vesicles (EV) can be produced as part of pathology and physiology with increased amounts in pathological conditions. EVs can carry and transfer cargo such as proteins, nucleic acids, and lipids to target cells and mediate intercellular communication resulting in modulation of gene expression, signaling pathways, and phenotype of recipient cells. EVs greatly influence the extracellular environment and the immune response. Their immunomodulatory properties are crucial in rheumatoid arthritis (RA), a condition marked by dysregulated immune response. EVs can modulate the functions of innate and adaptive immune cells in RA pathogenesis. Differentially expressed EV-associated molecules in RA, such as microRNAs (miRNAs), long-noncoding RNAs (lncRNAs), messenger RNAs (mRNAs) and proteins are promising markers to diagnose the disease. miRNA, lncRNA, and circular RNA (circRNA) cargos in EV regulate inflammation and the pathogenic functions of RA fibroblast-like synoviocytes (RA-FLS). Downregulated molecules in RA tissue and drugs can be encapsulated in EVs for RA therapy. This review provides an updated overview of EVs' immunomodulatory, diagnostic, and therapeutic roles, particularly emphasizing mesenchymal stem cell-derived EVs (MSC-EVs).

Yin-Yang: two sides of extracellular vesicles in inflammatory diseases

The concept of Yin-Yang, originating in ancient Chinese philosophy, symbolizes two opposing but complementary forces or principles found in all aspects of life. This concept can be quite fitting in the context of extracellular vehicles (EVs) and inflammatory diseases. Over the past decades, numerous studies have revealed that EVs can exhibit dual sides, acting as both pro- and anti-inflammatory agents, akin to the concept of Yin-Yang theory (i.e., two sides of a coin). This has enabled EVs to serve as potential indicators of pathogenesis or be manipulated for therapeutic purposes by influencing immune and inflammatory pathways. This review delves into the recent advances in understanding the Yin-Yang sides of EVs and their regulation in specific inflammatory diseases. We shed light on the current prospects of engineering EVs for treating inflammatory conditions. The Yin-Yang principle of EVs bestows upon them great potential as, therapeutic, and preventive agents for inflammatory diseases.

LncRNA expression profiling in exosomes derived from synovial fluid of patients with rheumatoid arthritis

OBJECTIVE

To identify the long non-coding RNA (lncRNA) expression profiling in exosomes derived from synovial fluid of rheumatoid arthritis (RA) patients, and carry out bioinformatics analysis on target genes of differentially expressed lncRNAs.

METHODS

Exosomes were isolated from synovial fluid via ultracentrifugation. RNAs were extracted from exosomes by using HiPure Liquid RNA/miRNA kits, followed by lncRNA sequencing. Differentially expressed lncRNAs in RA were screened, and bioinformatics analysis of their target genes was carried out. qRT-PCR was used to verify the lncRNA expression levels.

RESULTS

Compared with osteoarthritis (OA), 347 lncRNAs were found differentially expressed in RA. Compared with gout, 805 lncRNAs were found differentially expressed in RA. Compared with both OA and gout, 85 lncRNAs were found specially expressed in RA (65 were upregulated (including ENST00000433825.1)). Functional analysis of target genes of the specially expressed lncRNAs revealed significant enrichment of "autophagy" and "mTOR signaling pathway". The qRT-PCR results indicated that ENST00000433825.1 was highly expressed in RA, compared with both OA and gout (P < 0.05), which matched the lncRNA sequencing results. Correlation analysis showed that the level of ENST00000433825.1 in RA patients was significantly and positively correlated with the level of C-reactive protein (CRP) (P < 0.001).

CONCLUSIONS

The lncRNA expression profiling in exosomes derived from synovial fluid of RA was significantly different from OA and gout. ENST00000433825.1 was highly and uniquely expressed in RA and significantly and positively correlated with CRP, which might provide a diagnostic and therapeutic biomarker for RA.

Comprehensive Co-Inhibitory Receptor (Co-IR) Expression on T Cells and Soluble Proteins in Rheumatoid Arthritis

Co-inhibitory receptors (Co-IRs) are essential in controlling the progression of immunopathology in rheumatoid arthritis (RA) by limiting T cell activation. The objective of this investigation was to determine the phenotypic expression of Co-IR T cells and to assess the levels of serum soluble PD-1, PDL-2, and TIM3 in Taiwanese RA patients.

METHODS

Co-IRs T cells were immunophenotyped employing multicolor flow cytometry, and ELISA was utilized for measuring soluble PD-1, PDL-2, and TIM3. Correlations have been detected across the percentage of T cells expressing Co-IRs (MFI) and different indicators in the blood, including ESR, high-sensitivity CRP (hsCRP), 28 joint disease activity scores (DAS28), and soluble PD-1/PDL-2/TIM3.

RESULTS

In RA patients, we recognized elevated levels of PD-1 (CD279), CTLA-4, and TIGIT in CD4+ T cells; TIGIT, HLA-DR, TIM3, and LAG3 in CD8+ T cells; and CD8+CD279+TIM3+, CD8+HLA-DR+CD38+ T cells. The following tests were revealed to be correlated with hsCRP: CD4/CD279 MFI, CD4/CD279%, CD4/TIM3%, CD8/TIM3%, CD8/TIM3 MFI, CD8/LAG3%, and CD8+HLA-DR+CD38+%. CD8/LAG3 and CD8/TIM3 MFIs are linked to ESR. DAS28-ESR and DAS28-CRP exhibited relationships with CD4/CD127 MFI, CD8/CD279%, and CD8/CD127 MFI, respectively. CD4+CD279+TIM3+% was correlated with DAS28-ESR (p = 0.0084, N = 46), DAS28-CRP (p = 0.007, N = 47), and hsCRP (p = 0.002, N = 56), respectively. In the serum of patients with RA, levels of soluble PD-1, PDL-2, and Tim3 were extremely elevated. CD4+ TIM3+% (p = 0.0089, N = 46) and CD8+ TIM3+% (p = 0.0305, N = 46) were correlated with sTIM3 levels; sPD1 levels were correlated with CD4+CD279+% (p < 0.0001, N = 31) and CD3+CD279+% (p = 0.0084, N = 30).

CONCLUSIONS

Co-IR expressions on CD4+ and CD8+ T cells, as well as soluble PD-1, PDL-2, and TIM3 levels, could function as indicators of disease activity and potentially play crucial roles in the pathogenesis of RA.

Small extracellular vesicles have distinct CD81 and CD9 tetraspanin expression profiles in plasma from rheumatoid arthritis patients

Extracellular vesicles (EVs) are implicated in the pathogenesis of rheumatoid arthritis (RA) but little is known about the composition of specific small EV (sEV) subpopulations. This study aimed to characterize the CD63, CD81 and CD9 tetraspanin profile in the membrane of single EVs in plasma from treatment naïve RA patients and assess potential discrepancies between methotrexate (MTX) responder groups. EVs isolated from plasma were characterized using transmission electron microscopy, and detection of surface markers (CD63, CD81 and CD9) on single EVs was performed on the ExoView platform. All RA patients (N = 8) were newly diagnosed, treatment naïve, females, ACPA positive and former smokers. The controls (N = 5) were matched for age and gender. After three months of MTX treatment, responders (N = 4) were defined as those with ΔDAS28 > 1.2 and DAS28 ≤ 3.2 post-treatment. The isolated EVs were 50-200 nm in size. The RA patients had a higher proportion of both CD9 and CD81 single positive sEVs compared to healthy controls, while there was a decrease in CD81/CD9 double positive sEVs in patients. Stratification of RA patients into MTX responders and non-responders revealed a distinctly higher proportion of CD81 single positive sEVs in the responder group. The proportion of CD81/CD9 double positive sEVs (anti-CD9 captured) was lower in the non-responders, but increased upon 3 months of MTX treatment. Our exploratory study revealed distinct tetraspanin profiles in RA patients suggesting their implication in RA pathophysiology and MTX treatment response.

Structure of PD1 and its mechanism in the treatment of autoimmune diseases

PD-1 and CTLA-4 can play an important role in addressing the issue of autoimmune diseases. PD-1 is a transmembrane glycoprotein expressed on T, B, and Dentric cells. This molecule functions as a checkpoint in T cell proliferation. Ligation of PD-1 with its ligands inhibits the production of IL-2, IL-7, IL-10, and IL-12 as well as other cytokines by macrophages, natural killer (NK) cells, and T cells, which can suppress cell proliferation and inflammation. Today, scientists attempt to protect against autoimmune diseases by PD-1 inhibitory signals. In this review, we discuss the structure, expression, and signaling pathway of PD-1. In addition, we discuss the importance of PD-1 in regulating several autoimmune diseases, reflecting how manipulating this molecule can be an effective method in the immunotherapy of some autoimmune diseases.

T-cell derived extracellular vesicles prime macrophages for improved STING based cancer immunotherapy

A key phenomenon in cancer is the establishment of a highly immunosuppressive tumour microenvironment (TME). Despite advances in immunotherapy, where the purpose is to induce tumour recognition and hence hereof tumour eradication, the majority of patients applicable for such treatment still fail to respond. It has been suggested that high immunological activity in the tumour is essential for achieving effective response to immunotherapy, which therefore have led to exploration of strategies that triggers inflammatory pathways. Here activation of the stimulator of interferon genes (STING) signalling pathway has been considered an attractive target, as it is a potent trigger of pro-inflammatory cytokines and types I and III interferons. However, immunotherapy combined with targeted STING agonists has not yielded sustained clinical remission in humans. This suggests a need for exploring novel adjuvants to improve the innate immunological efficacy. Here, we demonstrate that extracellular vesicles (EVs), derived from activated CD4+ T cells (T-EVs), sensitizes macrophages to elevate STING activation, mediated by IFNγ carried on the T-EVs. Our work support that T-EVs can disrupt the immune suppressive environment in the tumour by reprogramming macrophages to a pro-inflammatory phenotype, and priming them for a robust immune response towards STING activation.

Cellular nanovesicles for therapeutic immunomodulation: A perspective on engineering strategies and new advances

Cellular nanovesicles which are referred to as cell-derived, nanosized lipid bilayer structures, have emerged as a promising platform for regulating immune responses. Owing to their outstanding advantages such as high biocompatibility, prominent structural stability, and high loading capacity, cellular nanovesicles are suitable for delivering various immunomodulatory molecules, such as small molecules, nucleic acids, peptides, and proteins. Immunomodulation induced by cellular nanovesicles has been exploited to modulate immune cell behaviors, which is considered as a novel cell-free immunotherapeutic strategy for the prevention and treatment of diverse diseases. Here we review emerging concepts and new advances in leveraging cellular nanovesicles to activate or suppress immune responses, with the aim to explicate their applications for immunomodulation. We overview the general considerations and principles for the design of engineered cellular nanovesicles with tailored immunomodulatory activities. We also discuss new advances in engineering cellular nanovesicles as immunotherapies for treating major diseases.

Soluble TIM-3 as a biomarker of progression and therapeutic response in cancers and other of human diseases

Immune checkpoints inhibition is a privileged approach to combat cancers and other human diseases. The TIM-3 (T cell immunoglobulin and mucin-domain containing-3) inhibitory checkpoint expressed on different types of immune cells is actively investigated as an anticancer target, with a dozen of monoclonal antibodies in (pre)clinical development. A soluble form sTIM-3 can be found in the plasma of patients with cancer and other diseases. This active circulating protein originates from the proteolytic cleavage by two ADAM metalloproteases of the membrane receptor shared by tumor and non-tumor cells, and extracellular vesicles. In most cancers but not all, overexpression of mTIM-3 at the cell surface leads to high level of sTIM-3. Similarly, elevated levels of sTIM-3 have been reported in chronic autoimmune diseases, inflammatory gastro-intestinal diseases, certain viral and parasitic diseases, but also in cases of organ transplantation and in pregnancy-related pathologies. We have analyzed the origin of sTIM-3, its methods of dosage in blood or plasma, its presence in multiple diseases and its potential role as a biomarker to follow disease progression and/or the treatment response. In contrast to sPD-L1 generated by different classes of proteases and by alternative splicing, sTIM-3 is uniquely produced upon ADAM-dependent shedding, providing a more homogenous molecular entity and a possibly more reliable molecular marker. However, the biological functionality of sTIM-3 remains insufficiently characterized. The review shed light on pathologies associated with an altered expression of sTIM-3 in human plasma and the possibility to use sTIM-3 as a diagnostic or therapeutic marker.

Do photosynthetic cells communicate with each other during cell death? From cyanobacteria to vascular plants

As in metazoans, life in oxygenic photosynthetic organisms relies on the accurate regulation of cell death. During development and in response to the environment, photosynthetic cells activate and execute cell death pathways that culminate in the death of a specific group of cells, a process known as regulated cell death (RCD). RCD control is instrumental, as its misregulation can lead to growth penalties and even the death of the entire organism. Intracellular molecules released during cell demise may act as 'survival' or 'death' signals and control the propagation of cell death to surrounding cells, even in unicellular organisms. This review explores different signals involved in cell-cell communication and systemic signalling in photosynthetic organisms, in particular Ca2+, reactive oxygen species, lipid derivates, nitric oxide, and eATP. We discuss their possible mode-of-action as either 'survival' or 'death' molecules and their potential role in determining cell fate in neighbouring cells. By comparing the knowledge available across the taxonomic spectrum of this coherent phylogenetic group, from cyanobacteria to vascular plants, we aim at contributing to the identification of conserved mechanisms that control cell death propagation in oxygenic photosynthetic organisms.

T-cell exhaustion in immune-mediated inflammatory diseases: New implications for immunotherapy

Immune-mediated inflammatory diseases(IMIDs) are referred to as highly disabling chronic diseases affecting different organs and systems. Inappropriate or excessive immune responses with chronic inflammation are typical manifestations. Usually in patients with chronic infection and cancer, due to long-term exposure to persistent antigens and inflammation microenvironment, T-cells are continuously stimulated and gradually differentiate into an exhausted state. Exhausted T-cells gradually lose effector function and characteristics of memory T-cells. However, existing studies have found that exhausted T-cells are not only present in the infection and tumor environment, but also in autoimmunity, and are associated with better prognosis of IMIDs. This suggests new prospects for the application of this reversible process of T-cell exhaustion in the treatment of IMID. This review will focus on the research progress of T-cell exhaustion in several IMIDs and its potential application for diagnosis and treatment in IMIDs.

Galectin-3 Decreases 4-1BBL Bioactivity by Crosslinking Soluble and Membrane Expressed 4-1BB

4-1BB is a T cell costimulatory receptor and a member of the tumor necrosis factor receptor superfamily. Here, we show that Galectin-3 (Gal-3) decreases the cellular response to its ligand (4-1BBL). Gal-3 binds to both soluble 4-1BB (s4-1BB) and membrane-bound 4-1BB (mem4-1BB), without blocking co-binding of 4-1BBL. In plasma, we detected complexes composed of 4-1BB and Gal-3 larger than 100 nm in size; these complexes were reduced in synovial fluid from rheumatoid arthritis. Both activated 4-1BB⁺ T cells and 4-1BB-transfected HEK293 cells depleted these complexes from plasma, followed by increased expression of 4-1BB and Gal-3 on the cell surface. The increase was accompanied by a 4-fold decrease in TNFα production by the 4-1BB^highGal-3⁺ T cells, after exposure to 4-1BB/Gal-3 complexes. In RA patients, complexes containing 4-1BB/Gal-3 were dramatically reduced in both plasma and SF compared with healthy plasma. These results support that Gal-3 binds to 4-1BB without blocking the co-binding of 4-1BBL. Instead, Gal-3 leads to formation of large soluble 4-1BB/Gal-3 complexes that attach to mem4-1BB on the cell surfaces, resulting in suppression of 4-1BBL’s bioactivity.

Co-Inhibitory Molecules – Their Role in Health and Autoimmunity; Highlighted by Immune Related Adverse Events

Immune checkpoint receptors are key players in regulating the immune response. They are responsible for both generating an immune response sufficient to kill invading pathogens, balancing the same response, and protecting against tissue destruction or the development of autoimmune events. The central role of the co-inhibitory receptors also referred to as inhibitory immune checkpoints, including PD-1 and CTLA-4 has become especially evident with the cancer treatments targeting these receptors. Blocking these pathways enhances the immune activity, resulting in both an increased chance of cancer clearance, at the same time induction of immune-related adverse events (irAE). Some of these irAE progress into actual autoimmune diseases with autoantibodies and symptoms, undistinguished from the naturally occurring diseases. This review will take advantage of the lessons learned from immune checkpoint blockade and relate this knowledge to our understanding of the same pathways in naturally occurring autoimmune diseases, mainly focusing on rheumatic diseases.

TIGIT as a Promising Therapeutic Target in Autoimmune Diseases

Co-inhibitory receptors (IRs) are molecules that protect host against autoimmune reactions and maintain peripheral self-tolerance, playing an essential role in maintaining immune homeostasis. In view of the substantial clinical progresses of negative immune checkpoint blockade in cancer treatment, the role of IRs in autoimmune diseases is also obvious. Several advances highlighted the substantial impacts of T cell immunoglobulin and ITIM domain (TIGIT), a novel IR, in autoimmunity. Blockade of TIGIT pathway exacerbates multiple autoimmune diseases, whereas enhancement of TIGIT function has been shown to alleviate autoimmune settings in mice. These data suggested that TIGIT pathway can be manipulated to achieve durable tolerance to treat autoimmune disorders. In this review, we provide an overview of characteristics of TIGIT and its role in autoimmunity. We then discuss recent approaches and future directions to leverage our knowledge of TIGIT as therapeutic target in autoimmune diseases.

Update on the role of extracellular vesicles in rheumatoid arthritis

Rheumatoid arthritis (RA) is a heterogeneous autoimmune disorder that leads to severe joint deformities, negatively affecting the patient's quality of life. Extracellular vesicles (EVs), which include exosomes and ectosomes, act as intercellular communication mediators in several physiological and pathological processes in various diseases including RA. In contrast, EVs secreted by mesenchymal stem cells perform an immunomodulatory function and stimulate cartilage repair, showing promising therapeutic results in animal models of RA. EVs from other sources, including dendritic cells, neutrophils and myeloid-derived suppressor cells, also influence the biological function of immune and joint cells. This review describes the role of EVs in the pathogenesis of RA and presents evidence supporting future studies on the therapeutic potential of EVs from different sources. This information will contribute to a better understanding of RA development, as well as a starting point for exploring cell-free-based therapies for RA.

Extracellular vesicles in anti-tumor immunity

To what extent extracellular vesicles (EVs) can impact anti-tumor immune responses has only started to get unraveled. Their nanometer dimensions, their growing number of subtypes together with the difficulties in defining their origin hamper their investigation. The existence of tumor cell lines facilitated advance in cancer EV understanding, while capturing information about phenotypes and functions of immune cell EVs in this context is more complex. The advent of immunotherapy with immune checkpoint inhibitors has further deepened the need to dissect the impact of EVs during immune activation and response, not least to contribute unraveling and preventing the generation of resistance occurring in the majority of patients. Here we discuss the factors that influence anddrive the immune response in cancer patients in the context of cancer therapeutics and the roles or possible functions that EVs can have in this scenario. With immune cell-derived EVs as leitmotiv, we will journey from EV discovery and subtypes through physiological and pathological functions, from similarities with tumor EVs to measures to revert detrimental consequences on immune responses to cancer.

Soluble PD-1 (sPD-1) is expressed in human macrophages

The PD-1/PD-L1 axis plays a crucial role in regulating the anti-tumour immune response. A soluble PD-1 protein (sPD-1) has previously been observed, which could block the binding of PD-L1 to PD-1. Tumour associated macrophages are abundant in tumours, and evidence suggest they express PD-1. However, whether they also express sPD-1 remains unclear. The objective of this study was to investigate expression of sPD-1 in two in vitro models of human macrophages: THP-1 cells and monocyte-derived macrophages (MDM). Cells were polarised with either LPS + IFN-γ or IL-4 + IL-13 or left unpolarised. PD-1 and sPD-1 mRNAs were measured using droplet digital PCR, sPD-1 protein by electrochemiluminescence immunoassay and PD-1 by flow cytometry. sPD-1 mRNA was induced in both THP-1 cells and MDM after polarisation with LPS + IFN-γ, while IL-4 + IL-13 induced sPD-1 mRNA in MDM only. sPD-1 protein was measurable in culture supernatants. These findings show that macrophages can be induced to express sPD-1.

The role of extracellular vesicles in rheumatoid arthritis: a systematic review

Rheumatoid arthritis (RA) is a chronic inflammatory disease that carries high social and economic costs and can lead to permanent disability. RA pathogenesis has not been completely elucidated yet. Extracellular vesicles (EVs) are membrane-contained vesicles released by cells playing a role in cell-to-cell communication and they could be involved in different diseases. Evidence on the involvement of EVs in RA is currently inconclusive. Therefore, a systematic review on the role of EVs in RA was performed in order to explore this relationship. This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The research was conducted on PubMed, Scopus, and Embase up to March 5, 2020: 41 studies were analyzed out of 674 screened. The total plasmatic and synovial fluid (SF) EV number seems increased in RA as compared with healthy controls. Both RA plasma and SF contained EVs subpopulations of heterogenous origin, especially derived from platelets and immune system cells. No univocal evidence emerged on miRNA expression and EV content profile within RA patients. EVs showed to enhance pro-inflammatory pathways, such as cytokines and chemokine release and TNF blockade seemed to revert this effect. Our work highlights the requirement to standardize study methodologies in order to make results comparable and draw conclusions that remain, at present, unclear.

Checkpoint Molecules in Rheumatology-or the Benefits of Being Exhausted

PURPOSE OF REVIEW

This review will focus on the most common co-inhibitory molecules, emphasizing the importance of these in relation to rheumatic disease.

RECENT FINDINGS

Checkpoint molecules are pivotal in determining the outcome of antigen activation. Checkpoint molecules consist of co-stimulatory and co-inhibitory molecules, where the first activates and the latter inhibits the antigen presentation process. Studies show that increased activity of co-inhibitory molecules is associated with a good prognosis in rheumatic diseases. Opposite, when cancer patients are treated with antibodies blocking the inhibitory pathways, autoimmune diseases, including arthritis, develop as immune-related adverse events (IrAE). This emphasizes the importance of these pathways in autoimmune disease. Co-inhibitory molecules are becoming increasingly interesting as future treatment targets in rheumatic conditions. Treatments with antibodies blocking these pathways result in IrAE, often manifesting as autoimmune rheumatic diseases. Therefore, a need to get acquainted with these molecules is growing so we can cope with future challenges in rheumatic diseases.

Extracellular Vesicles in Rheumatoid Arthritis and Systemic Lupus Erythematosus: Functions and Applications

In the last two decades, extracellular vesicles (EVs) have aroused wide interest among researchers in basic and clinical research. EVs, small membrane vesicles are released by almost all kinds of cells into the extracellular environment. According to many recent studies, EVs participate in immunomodulation and play an important role in the pathogenesis of autoimmune diseases. In addition, EVs have great potential in the diagnosis and therapy of autoimmune diseases. Here, we reviewed the latest research advances on the functions and mechanisms of EVs and their roles in the pathogenesis, diagnosis, and treatment of rheumatoid arthritis and systemic lupus erythematosus.

The PD-1:PD-L1 axis in Inflammatory Arthritis

The activation of antigen specific T cells during an immune response is a tightly regulated process at the level of both costimulatory and coinhibitory receptors. One such coinhibitory receptor or checkpoint inhibitor which has received much attention in the field of oncology is the programmed cell death protein 1 (PD-1). Blockade of PD-1 or its ligand PD-L1 has proven successful in the treatment of a wide variety of cancers, therefore highlighting an important role for this pathway in anti-tumour immune responses. However, a caveat of PD-1 therapy and boosting anti-tumour immune responses is the development of self-reactive T cells which can lead to the induction of various autoimmune or inflammatory diseases, referred to as immune- related adverse events (irAEs). The emergence of rheumatological irAEs such as Inflammatory Arthritis (IA) in recent years has highlighted the importance of PD-1 in maintaining self-tolerance. Furthermore, the emergence of rheumatology related irAEs raises an important question as to how defects in this pathway can contribute to spontaneous rheumatological disease. In this review, we describe the biological distribution, function and regulation of the PD-1 pathway, its potential role in IA and irAE related IA.

SAP interacts with CD28 to inhibit PD-1 signaling in T lymphocytes

T cell co-stimulation is important for the maintenance of immunologic tolerance. Co-inhibitory receptors including programmed cell death-1 (PD-1) confer peripheral tolerance to prevent autoimmunity. SAP (SH2D1A) is an adaptor molecule that is important in T cell signaling and has been shown to interact with signaling lymphocytic activation molecule (SLAM) family receptors also in the context of self-tolerance. We recently reported that SAP interferes with PD-1 function. In the current study, we investigated the levels of SAP and PD-1 in patients with rheumatoid arthritis (RA) to further understand what role they play in disease activity. We observed increased SAP levels in lymphocytes of RA patients and found that PD-1 levels correlated positively with RA disease activity. Additionally, we found that SAP interacts with CD28 to inhibit T cell signaling in vitro. This work demonstrates a putative molecular mechanism for SAP mediated PD-1 inhibition.

The relationship between TIGIT+ regulatory T cells and autoimmune disease

The role of regulatory T cells (Treg cell) in controlling autoimmune disease is an area of intense study. As such, the characterization and understanding the function of Treg markers has the potential to provide a considerable impact in developing treatments and understanding the pathogenesis of autoimmune diseases. One such inhibitory Treg cell marker that has been recently discovered is T cell immunoglobulin and ITIM domain (TIGIT). In this review, we discuss what is known about the expression and function of TIGIT on Treg cells, and we discuss the relationship between TIGIT expressing Treg cells and different autoimmune diseases such as atopic dermatitis, autoimmune thyroiditis, type 1 diabetes, autoimmune uveitis, aplastic anemia, multiple sclerosis, systemic lupus erythematosus, arthritis, and colitis.

The PD-1/PD-L pathway in rheumatic diseases

BACKGROUND/PURPOSE

Autoimmune diseases are diseases in which the body produces an abnormal immune response to self-antigens and damages its own tissues. Programmed death-1 (PD-1) and its ligands (PD-Ls) have been discovered to be important negative regulators of the immune system, playing crucial roles in autoimmunity.

METHODS

We analyzed the existing scientific literature dealing with this issue. In this review, the PD-1/PD-L pathway in the genetic susceptibility to and pathogenesis of rheumatic diseases is discussed. The PD-1/PD-L pathway might be helpful for diagnosing, evaluating the disease activity of and treating rheumatic diseases.

RESULTS

PD-1/PD-L gene polymorphisms are associated with a genetic predisposition to rheumatic disorders, which can provide reference information for diagnosis and disease activity. The conclusion of the crucial role of the PD-1/PD-L pathway in the pathogenesis of rheumatic diseases is consistent, but the details remain controversial. In some animal models, manipulating the PD-1/PD-L pathway could decrease disease severity. PD-1/PD-Ls may enable us to develop new therapeutics for patients with rheumatic diseases in the future.

CONCLUSION

The PD-1/PD-L pathway plays crucial roles in rheumatic disease. More work is needed to provide a better mechanistic understanding of the PD-1/PD-L pathway and to facilitate the precise therapeutic manipulation of this pathway.

Exosomes: Effectual players in rheumatoid arthritis

Rheumatoid arthritis is a well-known chronic inflammatory joint disorder. It encompasses systemic inflammation, autoimmunity and development of several joint abnormalities leading to the lifelong disability and increased mortality. Exosomes are nano-sized (30-100 nm) mammalian extracellular particles with essential properties to regulate biological processes and cellular signaling by transferring protein and genetic materials. Understanding the diversity in the exosomal contents and their corresponding targets may contribute to better recognition of the processes that are implicated in the development and progression of diseases such as autoimmune disorders. Exosomes may act as a potential biomarker for the diagnosis of autoimmune disorders. In the present review, we aimed to bring together the relevant evidence on the biology of exosomes in rheumatoid arthritis, and also discuss the recent findings regarding the diagnostic, prognostic and therapeutic promise of these nanoparticles.

Circulating microRNAs in extracellular vesicles as potential biomarkers for psoriatic arthritis in patients with psoriasis

BACKGROUND

Psoriatic arthritis (PsA) develops in ~30% of patients with psoriasis. The diagnosis of PsA is challenging, and there are no reliable molecular markers in clinical use. MicroRNAs are short non-coding regulatory RNAs, which can be actively packaged into extracellular vesicles (EVs) and secreted to the circulation.

OBJECTIVES

To explore whether plasma-derived EV microRNAs may serve as biomarkers for PsA in patients with psoriasis.

METHODS

Plasma samples were obtained from patients with cutaneous-only psoriasis (PsC) and patients with psoriasis and PsA. Plasma EVs were isolated using miRCURY™ Exosome Isolation Kit. RNA sequencing was used to identify differentially expressed EV miRNAs in the discovery phase (PsC, n = 15; PsA, n = 14). In the validation phase (PsC, n = 29; PsA, n = 28), 41 selected miRNAs were analysed in plasma EVs by qPCR. The association of the identified miRNAs with PsA was assessed by logistic regression analysis.

RESULTS

RNA sequencing identified 19 plasma EV miRNAs with significantly different levels between PsA and PsC in the discovery cohort. Significantly lower levels of plasma EV let-7b-5p and miR-30e-5p in PsA vs. PsC were confirmed in the validation cohort, and their decreased levels were found to be associated with the presence of PsA. ROC analysis revealed an AUC of 0.68 (95% CI 0.53-0.83) for let-7b-5p and 0.69 (95% CI 0.55-0.84) for miR-30e-5p.

CONCLUSIONS

Circulating EV microRNA levels are altered in patients with PsA as compared with PsC. Findings of this exploratory study suggest that circulating EV microRNAs may serve as biomarkers for arthritis in psoriasis patients.

Concentrates of two subsets of extracellular vesicles from cow's milk modulate symptoms and inflammation in experimental colitis

Extracellular vesicles (EVs) are involved in cell-to-cell communication and modulation of numerous physiological and pathological processes. EVs are found in large quantities in milk and contain several inflammation- and immunity-modulating proteins and microRNAs, through which they exert beneficial effects in several inflammatory disease models. Here, we investigated the effects of two EV subsets, concentrated from commercial cow's milk, on a murine model of colitis induced with dextran sodium sulfate (DSS). P35K EVs, isolated by ultracentrifugation at 35,000 g, and P100K EVs, isolated at 100,000 g, were previously characterized and administered by gavage to healthy and DSS-treated mice. P35K EVs and, to a lesser extent, P100K EVs improved several outcomes associated to DSS-induced colitis, modulated the gut microbiota, restored intestinal impermeability and replenished mucin secretion. Also, P35K EVs modulated innate immunity, while P100K EVs decreased inflammation through the downregulation of colitis-associated microRNAs, especially miR-125b, associated with a higher expression of the NFκB inhibitor TNFAIP3 (A20). These results suggest that different milk EV subsets may improve colitis outcomes through different, and possibly complementary, mechanisms. Further unveiling of these mechanisms might offer new opportunities for improving the life of patients with colitis and be of importance for milk processing, infant milk formulation and general public health.

MicroRNAs in rheumatoid arthritis: From pathogenesis to clinical impact

Over the last decade, many epigenetic mechanisms that contribute in the pathogenesis of autoimmune disorders have been revealed. MicroRNAs (miRNAs) are small, non-coding, RNA molecules that bind to messenger RNAs and disrupt the transcription of target genes. Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease in which a plethora of epigenetic changes take place. Current research on RA epigenetics has focused mainly on miRNAs. Genetic variance of some miRNA genes, especially miR-499, might predispose an individual to RA development. Additionally, altered expression of many miRNAs has been discovered in several cells, tissues and body fluids in patients with RA. MiRNAs expression also differs depending on disease's stage and activity. Serum miR-22 and miR-103a might predict RA development in susceptible individuals (pre-RA), while serum miR-16, miR-24, miR-125a and miR-223 levels are altered in early RA (disease duration <12 months) patients compared to established RA or healthy individuals. Moreover, serum miR-223 levels have been associated with RA activity and disease relapse. What is more, serum levels of several miRNAs, including miR-125b and miR-223, could be used to predict response to RA treatment. Finally, miRNA analogs or antagonists have been used as therapeutic regimens in experimental arthritis models and have demonstrated promising results. In conclusion, the research on the miRNA alterations in RA sheds light to several aspects of RA pathogenesis, introduces new biomarkers for RA diagnosis and treatment response prediction and offers the opportunity to discover new, targeted drugs for patients with RA.

Association between cytokines and exosomes in synovial fluid of individuals with knee osteoarthritis

Background: Cytokines in synovial fluid (SF) play a crucial role in knee osteoarthritis (KOA). Exosomes are nanovesicles that are abundant in SF and carry a large quantity of signaling molecules. The purpose of this study was to evaluate the cytokine profiles of SF-derived exosomes and try to explore its biological function.Methods: Twenty-four KOA patients who were scheduled for their first intra-articular injection or knee replacement surgery were enrolled and divided into the KL1-2 group and the KL3-4 group according to the Kellgren and Lawrence (KL) classification. SF was collected from the patient's knee for the isolation of exosomes. A multiplex cytokine assay was performed to detect the 21 cytokines in the exosomes. The SF derived-exosomes were exposed to PBMCs and chondrocytes to assess their immunomodulatory potential.Results: Exosomes were successfully extracted from the SF, with an average diameter of 92 nm. Most cytokines were detectable in the SF-derived exosomes. Twelve inflammatory cytokines and eight chemokines were elevated in the exosomes of the KL3-4 group compared to that of the KL1-2 group (p < .05). A higher number of PBMCs were chemo attracted and the proliferation of chondrocytes was restrained by the SF-derived exosomes from the KL3-4 group in comparison with the KL1-2 group (p < .05).Conclusion: Our data indicated that most cytokines in SF are not only in a free form but also associated with and enriched in exosomes. Exosomes from end-stage KOA patients have a higher level of cytokines, especially chemokines, in comparison with the cytokine profiles of the soluble SF. SF-derived exosomes recruit inflammatory cells and inhibit cartilage proliferation, thus promoting joint degeneration. These data provide a new perspective for understanding the changes in the inner environment of KOA.

Characterization of cell-derived microparticles in synovial fluid and plasma of patients with rheumatoid arthritis

Microparticles (MP) are proposed to play a role in the pathogenesis of rheumatoid arthritis (RA). This study aimed to profile cell lineage-specific MP in patients with RA, osteoarthritis (OA), and healthy controls (HC) in synovial fluid and circulation. Patients with RA (n = 40), OA (n = 30) and HC (n = 33) were included. Cell-free synovial fluid (SF) and platelet-poor plasma samples were stained with annexin V APC and antibodies against CD45, CD20, CD14, CD4, CD8, CD66b, and CD61 for multicolor flow cytometry. Mann-Whitney U test/unpaired T test was used to assess intergroup differences among RA and OA SF and clinical, serological phenotypes of RA based on normality distribution; Kruskal-Wallis test with Dunn's multiple comparisons for comparing plasma MPs among RA, OA, and HC. Correlation between MP proportions and disease parameters was assessed by Spearman's correlation. The proportion of annexin V⁺ MP in SF of patients with RA [5 (6.35)] [median (IQR)] was higher compared to OA [1.8 (1.35), p < 0.001] and plasma of patients with RA [3.45 (5.63)] compared to OA [1.85 (1.4)] and HC [0.9 (1.1), p < 0.001]. Leukocyte-derived [0.85 (1.17)], granulocyte-derived [0.4 (2.05)], monocyte-derived [0.4 (0.4)], and T cell-derived MP [CD4⁺ - 0.1 (0.1); CD8⁺ - 0.1(0.1)] were higher in RA SF (p < 0.001). Platelet-derived MP (PMP) were the major fraction [1.5 (4.23), p < 0.001] in RA plasma. Leukocyte-derived MP were higher in RA plasma [0.1 (0.2); p < 0.001) than OA and HC. Annexin V⁺ MP and PMP were higher in the SF of RA with extra-articular manifestations (n = 15), as compared to those without (n = 25) (p = 0.02; p < 0.01, respectively). High SF granulocyte-derived MP were observed in patients with established RA (n = 24), ACPA-positive RA (n = 32) compared to their negative counterparts (p = 0.03; p = 0.02, respectively). Our observations of higher proportions of cell-derived MP in the plasma and synovial fluid of DMARD-naïve RA patients, their clinical and serological phenotypes suggest their role in dynamic cross talk between the joint and systemic circulation, disease pathology, and progression.

Extracellular Vesicles in Joint Disease and Therapy

The use of extracellular vesicles (EVs) as a potential therapy is currently explored for different disease areas. When it comes to the treatment of joint diseases this approach is still in its infancy. As in joint diseases both inflammation and the associated articular tissue destruction are important factors, both the immune-suppressive and the regenerative properties of EVs are potentially advantageous characteristics for future therapy. There is, however, only limited knowledge on the basic features, such as numerical profile and function, of EVs in joint articular tissues in general and their linking medium, the synovial fluid, in particular. Further insight is urgently needed in order to appreciate the full potential of EVs and to exploit these in EV-mediated therapies. Physiologic joint homeostasis is a prerequisite for proper functioning of joints and we postulate that EVs play a key role in the regulation of joint homeostasis and hence can have an important function in re-establishing disturbed joint homeostasis, and, in parallel, in the regeneration of articular tissues. In this mini-review EVs in the joint are explained from a historical perspective in both health and disease, including the potential niche for EVs in articular tissue regeneration. Furthermore, the translational potential of equine models for human joint biology is discussed. Finally, the use of MSC-derived EVs that is recently gaining ground is highlighted and recommendations are given for further EV research in this field.

Identification of protein markers for extracellular vesicle (EV) subsets in cow's milk

Extracellular vesicles (EVs), like exosomes, are small membrane vesicles involved in cell-to-cell communications that modulate numerous biological processes. We previously discovered a new EV subset in milk (sedimenting at 35,000 g; 35 K) that protected its cargo (RNAs and proteins) during simulated digestion and was more enriched in microRNAs than exosomes (sedimenting at 100 K). Here, we used LC-MS/MS to push further the comparison between these two pellets. Commonly used EV markers were not differentially enriched between the pellets, questioning their use with cow's milk EVs. Similarly, the majority of the quantified proteins were equally enriched between the two pellets. Nevertheless, 20 proteins were specific to 35 K, while 41 were specifically enriched in 100 K (p < 0.05), suggesting their potential use as specific markers. Loaded with these proteins, the EVs in these pellets might regulate translation, proliferation and cell survival for 35 K, and metabolism, extracellular matrix turnover and immunity for 100 K. This approach also brought new insights into milk EV-associated integrins and their possible role in specifically targeting recipient cell types. These findings may help better discriminate between milk EVs, improve our understanding of milk EV-associated protein function and their possible use as therapeutic tools for the management of immunity- and metabolism-associated disorders. WEB PAGE: http://www.crchuq.ca/en/research/researchers/4691.

Rheumatic manifestations among cancer patients treated with immune checkpoint inhibitors

BACKGROUND

The use of immune checkpoint inhibitors (ICI) has grown incessantly since they were first approved in 2014. These monoclonal antibodies inhibit T cell activation, yielding a dramatic tumor response with improved survival. However, immunotherapy is frequently hampered by immune adverse events (iAE) such as hypophysitis, colitis, hepatitis, pneumonitis and rash. Until recently, rheumatic side effects were only infrequently reported.

AIM

To describe the rheumatic manifestations encountered among patients treated with ICIs in a large tertiary cancer center in Israel METHODS: The cancer center's patient registry was screened for patients who had ever been treated with ipilimumab, pembrolizumab and/or nivolumab with relevant data gathered from clinical charts.

RESULTS

Rheumatic manifestations were encountered in 14 of 400 patients (3.5%) who had received immunotherapy between January 1st 2013 and April 30th, 2017. The most common rheumatic manifestation was inflammatory arthritis (85%) for which a third (4/11) had a clear cut predisposing factor such as a personal or family history of psoriasis, a prior episode of uveitis or ACPA positivity. Pulmonary sarcoidosis and biopsy-proven eosinophilic fasciitis were diagnosed in two additional patients. Treatment with NSAIDS was mostly unsuccessful while steroid therapy was beneficial in doses ≥20 mg/d. Methotrexate enabled steroid tapering without an excess of side effects or tumor progression in the short follow-up available. Overall, rheumatic manifestations tended to occur later in the course of immunotherapy as compared to other iAE.

CONCLUSIONS

Our findings underscore that rheumatic iAE are part of the side effect profile of ICIs and require heightened awareness as these therapies are becoming the standard of care for various malignancies. We show that these appear later in the course of iAEs and respond preferentially to high dose steroids. MTX appears effective as a steroid sparing agent.