CTLA4-Ig interacts with cultured synovial macrophages from rheumatoid arthritis patients and downregulates cytokine production

Crosstalk between efferocytic myeloid cells and T-cells and its relevance to atherosclerosis

The interplay between myeloid cells and T-lymphocytes is critical to the regulation of host defense and inflammation resolution. Dysregulation of this interaction can contribute to the development of chronic inflammatory diseases. Important among these diseases is atherosclerosis, which refers to focal lesions in the arterial intima driven by elevated apolipoprotein B-containing lipoproteins, notably low-density lipoprotein (LDL), and characterized by the formation of a plaque composed of inflammatory immune cells, a collection of dead cells and lipids called the necrotic core, and a fibrous cap. As the disease progresses, the necrotic core expands, and the fibrous cap becomes thin, which increases the risk of plaque rupture or erosion. Plaque rupture leads to a rapid thrombotic response that can give rise to heart attack, stroke, or sudden death. With marked lowering of circulating LDL, however, plaques become more stable and cardiac risk is lowered-a process known as atherosclerosis regression. A critical aspect of both atherosclerosis progression and regression is the crosstalk between innate (myeloid cells) and adaptive (T-lymphocytes) immune cells. Myeloid cells are specialized at clearing apoptotic cells by a process called efferocytosis, which is necessary for inflammation resolution. In advanced disease, efferocytosis is impaired, leading to secondary necrosis of apoptotic cells, inflammation, and, most importantly, defective tissue resolution. In regression, efferocytosis is reawakened aiding in inflammation resolution and plaque stabilization. Here, we will explore how efferocytosing myeloid cells could affect T-cell function and vice versa through antigen presentation, secreted factors, and cell-cell contacts and how this cellular crosstalk may contribute to the progression or regression of atherosclerosis.

Molecular mechanism of quercetin in treating RA-ILD based on network pharmacology, molecular docking, and experimental validation

Rheumatoid arthritis (RA) is an autoimmune disease that is associated with systemic complications. Interstitial lung disease (ILD) is the most common pulmonary complication and second leading cause of death in patients with RA. In this study, we used network pharmacology and experimental validation to identify the targets and pathways of quercetin (Que) in the treatment of RA-associated ILD (RA-ILD). A total of 32 potential targets of Que for RA-ILD treatment were screened from six databases, and 10 core targets were screened using protein-protein interaction network analysis. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, and molecular docking were employed to explore the potential mechanisms of Que in RA-ILD treatment. The results suggested the IL-17 signaling pathway as an important pathway through which Que alleviates RA-ILD. Subsequently, LPS (1 µg/ml) was used to establish an inflammation model on RAW 264.7 cells, and different concentrations of Que (25, 50, and 100 µM) were used for intervention. Que significantly reduced the expression levels of IL-17, TNF-α, IL-6, and IL-1β in RAW 264.7 cells. Our findings suggest that Que alleviates RA-ILD by regulating the IL-17 signaling pathway and reducing inflammation.

Efficacy of COVID-19 mRNA vaccination in patients with autoimmune disorders: humoral and cellular immune response

BACKGROUND

The impact of immunosuppressive therapies on the efficacy of vaccines to SARS-CoV-2 is not completely clarified. We analyzed humoral and T cell-mediated response after COVID-19 mRNA vaccine in immunosuppressed patients and patients with common variable immunodeficiency disease (CVID).

PATIENTS

We enrolled 38 patients and 11 healthy sex- and age-matched controls (HC). Four patients were affected by CVID and 34 by chronic rheumatic diseases (RDs). All patients with RDs were treated by corticosteroid therapy and/or immunosuppressive treatment and/or biological drugs: 14 patients were treated with abatacept, 10 with rituximab, and 10 with tocilizumab.

METHODS

Total antibody titer to SARS-CoV-2 spike protein was assessed by electrochemiluminescence immunoassay, CD4 and CD4-CD8 T cell-mediated immune response was analyzed by interferon-γ (IFN-γ) release assay, the production of IFN-γ-inducible (CXCL9 and CXCL10) and innate-immunity chemokines (MCP-1, CXCL8, and CCL5) by cytometric bead array after stimulation with different spike peptides. The expression of CD40L, CD137, IL-2, IFN-γ, and IL-17 on CD4 and CD8 T cells, evaluating their activation status, after SARS-CoV-2 spike peptides stimulation, was analyzed by intracellular flow cytometry staining. Cluster analysis identified cluster 1, namely the "high immunosuppression" cluster, and cluster 2, namely the "low immunosuppression" cluster.

RESULTS

After the second dose of vaccine, only abatacept-treated patients, compared to HC, showed a reduced anti-spike antibody response (mean: 432 IU/ml ± 562 vs mean: 1479 IU/ml ± 1051: p = 0.0034), and an impaired T cell response, compared with HC. In particular, we found a significantly reduced release of IFN-γ from CD4 and CD4-CD8 stimulated T cells, compared with HC (p = 0.0016 and p = 0.0078, respectively), reduced production of CXCL10 and CXCL9 from stimulated CD4 (p = 0.0048 and p = 0.001) and CD4-CD8 T cells (p = 0.0079 and p = 0.0006). Multivariable General Linear Model analysis confirmed a relationship between abatacept exposure and impaired production of CXCL9, CXCL10, and IFN-γ from stimulated T cells. Cluster analysis confirms that cluster 1 (including abatacept and half of rituximab treated cases) showed a reduced IFN-γ response, as well as reduced monocyte-derived chemokines All groups of patients demonstrated the ability to generate specific CD4 T activated cells after spike proteins stimulation. After the third dose of vaccine, abatacept-treated patients acquired the ability to produce a strong antibody response, showing an anti-S titer significantly higher compared to that obtained after the second dose (p = 0.0047), and comparable with the anti-S titer of the other groups.

CONCLUSIONS

Patients treated with abatacept showed an impaired humoral immune response to two doses of COVID-19 vaccine. The third vaccine dose has been demonstrated to be useful to induce a more robust antibody response to balance an impaired T cell-mediated one. All patients, exposed to different immunosuppressive drugs, were able to produce specific CD4-activated T cells, after spike proteins stimulation.

TRIAL REGISTRATION

Local Ethical Committee NP4187.

New insights into inflammatory osteoclast precursors as therapeutic targets for rheumatoid arthritis and periodontitis

Rheumatoid arthritis (RA) and periodontitis are chronic inflammatory diseases leading to increased bone resorption. Preventing this inflammatory bone resorption is a major health challenge. Both diseases share immunopathogenic similarities and a common inflammatory environment. The autoimmune response or periodontal infection stimulates certain immune actors, leading in both cases to chronic inflammation that perpetuates bone resorption. Moreover, RA and periodontitis have a strong epidemiological association that could be explained by periodontal microbial dysbiosis. This dysbiosis is believed to be involved in the initiation of RA via three mechanisms. (i) The dissemination of periodontal pathogens triggers systemic inflammation. (ii) Periodontal pathogens can induce the generation of citrullinated neoepitopes, leading to the generation of anti-citrullinated peptide autoantibodies. (iii) Intracellular danger-associated molecular patterns accelerate local and systemic inflammation. Therefore, periodontal dysbiosis could promote or sustain bone resorption in distant inflamed joints. Interestingly, in inflammatory conditions, the existence of osteoclasts distinct from "classical osteoclasts" has recently been reported. They have proinflammatory origins and functions. Several populations of osteoclast precursors have been described in RA, such as classical monocytes, a dendritic cell subtype, and arthritis-associated osteoclastogenic macrophages. The aim of this review is to synthesize knowledge on osteoclasts and their precursors in inflammatory conditions, especially in RA and periodontitis. Special attention will be given to recent data related to RA that could be of potential value in periodontitis due to the immunopathogenic similarities between the two diseases. Improving our understanding of these pathogenic mechanisms should lead to the identification of new therapeutic targets involved in the pathological inflammatory bone resorption associated with these diseases.

Multiple Shades of Gray-Macrophages in Acute Allograft Rejection

Long-term results following solid organ transplantation do not mirror the excellent short-term results achieved in recent decades. It is therefore clear that current immunosuppressive maintenance protocols primarily addressing the adaptive immune system no longer meet the required clinical need. Identification of novel targets addressing this shortcoming is urgently needed. There is a growing interest in better understanding the role of the innate immune system in this context. In this review, we focus on macrophages, which are known to prominently infiltrate allografts and, during allograft rejection, to be involved in the surge of the adaptive immune response by expression of pro-inflammatory cytokines and direct cytotoxicity. However, this active participation is janus-faced and unspecific targeting of macrophages may not consider the different subtypes involved. Under this premise, we give an overview on macrophages, including their origins, plasticity, and important markers. We then briefly describe their role in acute allograft rejection, which ranges from sustaining injury to promoting tolerance, as well as the impact of maintenance immunosuppressants on macrophages. Finally, we discuss the observed immunosuppressive role of the vitamin-like compound tetrahydrobiopterin and the recent findings that suggest the innate immune system, particularly macrophages, as its target.

Past, Present, and Future in Dermatomyositis Therapeutics

Purpose of review

This review highlights current and emerging pharmacologic therapies for the treatment of dermatomyositis (DM). Current clinical evidence, in addition to recently published and ongoing clinical trials for various drugs in development, are summarized in this review.

Recent findings

There has been significant progress in the research and development of potential treatments in DM. The FDA recently approved Octagam® 10% Immune Globulin Intravenous (IVIg) for the treatment of DM. Several drug targets are being explored as viable therapeutic options in phase 2 and phase 3 clinical trials; at the forefront of these are JAK inhibitors (tofacitinib and baricitinib) and T-cell co-stimulation blockers (i.e. abatacept). In addition, clinical trials are currently under way for therapeutics targeting novel molecular pathways, including immunoproteasome inhibitors, anti-B cell therapy, anti-interferon drugs, complement inhibitors, and phosphodiesterase-4 inhibitors.

Summary

With the large number of clinical trials, multiple novel therapeutics in development, and improved classification and outcome measures, the treatment landscape for DM will continue to rapidly evolve in the coming years as more options become available.

Abatacept downregulates Fcγ receptor I on circulating monocytes: a potential therapeutic mechanism in patients with rheumatoid arthritis

Background

Abatacept is a recombinant fusion protein composed of the extracellular domain of cytotoxic T-lymphocyte antigen 4 and the Fc portion of immunoglobulin (Ig) G. The mechanism of action of abatacept in rheumatoid arthritis (RA) is believed to be competitive inhibition of T cell costimulation mediated by the binding of CD28 to CD80/CD86 on antigen-presenting cells, and recent studies have shown that abatacept induces reverse signaling in macrophages and osteoclast precursors in a T cell-independent manner. This study aimed to investigate the therapeutic effects of abatacept on circulating monocytes that contribute to RA pathogenesis.

Methods

Purified circulating monocytes derived from RA patients and controls were cultured in the absence or presence of abatacept or CD28-Ig for 24 h. The recovered cells were subjected to flow cytometry to evaluate the expression levels of cell surface molecules, and cytokines and chemokines in the culture supernatant were measured by multiplex bead arrays. The expression of candidate molecules was further examined by immunoblotting using total cellular extracts of the cultured monocytes. Finally, the effects of abatacept on cytokine production in monocytes stimulated with the immune complex of anti-citrullinated peptide antibodies (ACPAs) were examined.

Results

CD64/FcγRI was identified as a monocyte-derived molecule that was downregulated by abatacept but not CD28-Ig. This effect was observed in both RA patients and controls. The abatacept-induced downregulation of CD64/FcγRI was abolished by treatment with anti-CD86 antibodies but not anti-CD80 antibodies. Abatacept suppressed the production of interleukin (IL)-1β, IL-6, C-C motif chemokine ligand 2, and tumor necrosis factor-α in cultured monocytes stimulated with the ACPA immune complex.

Conclusions

The therapeutic effects of abatacept on RA are mediated, in part, by the downregulation of CD64/FcγRI on circulating monocytes via direct binding to CD86 and the suppression of immune complex-mediated inflammatory cytokine production.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-022-02886-8.

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.

The Role of M1/M2 Macrophage Polarization in Rheumatoid Arthritis Synovitis

Innate and adaptive immunity represent a harmonic counterbalanced system involved in the induction, progression, and possibly resolution of the inflammatory reaction that characterize autoimmune rheumatic diseases (ARDs), including rheumatoid arthritis (RA). Although the immunopathophysiological mechanisms of the ARDs are not fully clarified, they are often associated with an inappropriate macrophage/T-cell interaction, where classical (M1) or alternative (M2) macrophage activation may influence the occurrence of T-helper (Th)1 or Th2 responses. In RA patients, M1/Th1 activation occurs in an inflammatory environment dominated by Toll-like receptor (TLR) and interferon (IFN) signaling, and it promotes a massive production of pro-inflammatory cytokines [i.e., tumor necrosis factor-α (TNFα), interleukin (IL)-1, IL-12, IL-18, and IFNγ], chemotactic factors, and matrix metalloproteinases resulting in osteoclastogenesis, erosion, and progressive joint destruction. On the other hand, the activation of M2/Th2 response determines the release of growth factors and cytokines [i.e., IL-4, IL-10, IL-13, and transforming growth factor (TGF)-β] involved in the anti-inflammatory process leading to the clinical remission of RA. Several subtypes of macrophages have been described. Five polarization states from M1 to M2 have been confirmed in in vitro studies analyzing morphological characteristics, gene expression of phenotype markers (CD80, CD86, TLR2, TLR4, or CD206, CD204, CD163, MerTK), and functional aspect, including the production of reactive oxygen species (ROS). An M1 and M2 macrophage imbalance may induce pathological consequences and contribute to several diseases, such as asthma or osteoclastogenesis in RA patients. In addition, the macrophage dynamic polarization from M1 to M2 includes the presence of intermediate polarity stages distinguished by the expression of specific surface markers and the production/release of distinct molecules (i.e., nitric oxide, cytokines), which characterize their morphological and functional state. This suggests a “continuum” of macrophage activation states playing an important role during inflammation and its resolution. This review discusses the importance of the delicate M1/M2 imbalance in the different phases of the inflammatory process together with the identification of specific pathways, cytokines, and chemokines involved, and its clinical outcomes in RA. The analysis of these aspects could shed a light on the abnormal inflammatory activation, leading to novel therapeutical approaches which may contribute to restore the M1/M2 balance.

Repolarization of Unbalanced Macrophages: Unmet Medical Need in Chronic Inflammation and Cancer

Monocytes and their tissue counterpart macrophages (MP) constitute the front line of the immune system. Indeed, they are able to rapidly and efficiently detect both external and internal danger signals, thereby activating the immune system to eradicate the disturbing biological, chemical, or physical agents. They are also in charge of the control of the immune response and account for the repair of the damaged tissues, eventually restoring tissue homeostasis. The balance between these dual activities must be thoroughly controlled in space and time. Any sustained unbalanced response of MP leads to pathological disorders, such as chronic inflammation, or favors cancer development and progression. In this review, we take advantage of our expertise in chronic inflammation, especially in rheumatoid arthritis, and in cancer, to highlight the pivotal role of MP in the physiopathology of these disorders and to emphasize the repolarization of unbalanced MP as a promising therapeutic strategy to control these diseases.

CTLA4-Ig treatment induces M1-M2 shift in cultured monocyte-derived macrophages from healthy subjects and rheumatoid arthritis patients

Background

In rheumatoid arthritis (RA), macrophages play an important role in modulating the immunoinflammatory response through their polarisation into “classically” (M1) or “alternatively activated” (M2) phenotypes. In RA, CTLA4-Ig (abatacept) reduces the inflammatory activity of macrophages by interacting with the costimulatory molecule CD86. The study aimed to investigate the efficacy of CTLA4-Ig treatment to induce an M2 phenotype both in M1-polarised monocyte-derived macrophages (MDMs) obtained from healthy subjects (HS) and in cultured MDMs obtained from active RA patients.

Methods

Cultured MDMs were obtained from peripheral blood mononuclear cells of 7 active RA patients and from 10 HS after stimulation with phorbol myristate acetate (5 ng/mL) for 24 h. HS-MDMs were then stimulated with lipopolysaccharide (LPS, 1 mg/mL) for 4 h to induce M1-MDMs. M1-MDMs and RA-MDMs were treated with CTLA4-Ig (100 μM and 500 μM) for 3, 12, 24, and 48 h. The gene expression of CD80, CD86, and TLR4 (M1 markers); CD163, CD204, and CD206 (surface M2 markers); and MerTK (functional M2 marker) was evaluated by qRT-PCR. The protein synthesis of surface M2 markers was investigated by Western blotting. The statistical analysis was performed by the Wilcoxon t-test.

Results

In LPS-induced HS-M1-MDMs, CTLA4-Ig 100 μM and 500 μM significantly downregulated the gene expression of M1 markers (3 h p<0.01 for all molecules; 12 h p<0.05 for TLR4 and CD86) and significantly upregulated that of M2 markers, primarily after 12 h of treatment (CD163: p < 0.01 and p < 0.05; CD206: p < 0.05 and p < 0.01; CD204: p < 0.05 by 100 mg/mL). Moreover, in these cells, CTLA4-Ig 500 μM increased the protein synthesis of surface M2 markers (p < 0.05). Similarly, in RA-MDMs, the CTLA4-Ig treatment significantly downregulated the gene expression of M1 markers at both concentrations primarily after 12 h (p < 0.05). Furthermore, both concentrations of CTLA4-Ig significantly upregulated the gene expression of CD206 (after 3 h of treatment; p < 0.05), CD163, and MerTK (after 12 h of treatment, p < 0.05), whereas CD204 gene expression was significantly upregulated by the high concentration of CTLA4-Ig (p < 0.05). The protein synthesis of all surface markers was increased primarily by CTLA4-Ig 500 μM, significantly for CD204 and CD206 after 24 h of treatment (p < 0.05).

Conclusions

CTLA4-Ig treatment seems to induce the in vitro shift from M1 to M2 macrophages, of both HS-M1-MDMs and RA-MDMs, as observed by the significant downregulation exerted on selected M1 markers and the upregulation of selected M2 markers suggesting an additional mechanism for its modulation of the RA inflammatory process.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02691-9.

Association between CTLA-4 gene polymorphism and risk of rheumatoid arthritis: a meta-analysis

Cytotoxic T lymphocyte-associated protein 4 (CTLA-4) gene polymorphisms may be involved in the risk of Rheumatoid arthritis (RA). However, evidence for the association remains controversial. Therefore, we performed a meta-analysis to confirm the relationship between CTLA-4 gene polymorphisms and RA. The pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the strength of association. Stratified analysis was conducted by ethnicity. In total, 66 case-control studies including 21681 cases and 23457 controls were obtained. For rs3087243 polymorphism, significant association was detected in Asians (A vs. G: OR=0.77, 95%CI=0.65-0.90, P=0.001; AA vs. GG: OR=0.67, 95%CI=0.48-0.94, P=0.02) and Caucasians (A vs. G: OR=0.89, 95%CI=0.86-0.93, P<0.00001; AA vs. GG: OR=0.81, 95%CI=0.75-0.88, P<0.00001). For rs231775 polymorphism, significant association was observed in the overall (G vs. A: OR =1.16, 95%CI=1.08-1.25, P<0.0001; GG vs. AA: OR=1.29, 95%CI=1.12-1.50, P=0.0006), and in Asians (G vs. A: OR=1.27, 95%CI=1.10-1.47, P=0.001; GG vs. AA: OR=1.58, 95%CI=1.24-2.01, P=0.0002), but not in Caucasians. However, there was no association between rs5742909 polymorphism and RA. This meta-analysis confirmed that rs3087243 and rs231775 polymorphism were associated with the risk of RA in both overall population and ethnic-specific analysis, but there was no association between rs5742909 polymorphism and RA risk.

Novel insights into macrophage diversity in rheumatoid arthritis synovium

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease affecting joints and causing progressive damage and disability. Macrophages are of critical importance in the initiation and perpetuation of synovitis in RA, they can function as antigen presenting cells leading to T-cell dependent B-cell activation, assume a variety of inflammatory cell states with the production of destructive cytokines, but also contribute to tissue homeostasis/repair. The recent development of high-throughput technologies, including bulk and single cells RNA-sequencing, has broadened our understanding of synovial cell diversity, and opened novel perspectives to the discovery of new potential therapeutic targets in RA. In this review, we will focus on the relationship between the synovial macrophage infiltration and clinical disease severity and response to treatment. We will then provide a state-of-the-art picture of the biological roles of synovial macrophages and distinct macrophage subsets described in RA. Finally, we will review the effects of approved conventional and biologic drugs on the synovial macrophage component and highlight the therapeutic potential of future strategies to re-program macrophage phenotypes in RA.

Clinical trials and novel therapeutics in dermatomyositis

INTRODUCTION

Currently, there are no proven drugs that are FDA approved for the treatment of dermatomyositis (DM), even though multiple clinical trials are ongoing to evaluate safety and efficacy of novel therapeutics in DM. The purpose of this review is to highlight the biological plausibility, existing clinical evidence as well as completed and ongoing clinical trials for various drugs in pipeline for development for use in dermatomyositis.

AREAS COVERED

The drugs with the strongest evidence have been included in this review with a focus on the mechanism of their action pertaining to the disease process, clinical studies including completed and ongoing trials. With better understanding of the underlying pathophysiologic process, there are new molecular targets that have been identified that can be targeted by these novel drugs, predominantly biologic drugs.

EXPERT OPINION

There are various drugs being evaluated in phase II/III clinical trials that hold promise in DM. At the forefront of these are immunoglobulin, Lenabasum, and Abatacept for which phase III clinical trials are ongoing. In addition, promising clinical studies are ongoing or reported for KZR-616, anti-B cell therapy, anti-interferon drugs, and Repository Corticotrophin Injection (RCI).

Cytotoxic T lymphocyte-associated antigen-4-Ig (CTLA-4-Ig) suppresses Staphylococcus aureus-induced CD80, CD86, and pro-inflammatory cytokine expression in human B cells

Background

Cytotoxic T lymphocyte-associated antigen-4-Ig (CTLA-4-Ig) competes with CD28 for binding CD80/CD86 on antigen-presenting cells (APCs) to limit T cell activation. B cells are believed to be important APCs in the pathogenesis of autoimmune diseases and express CD80/CD86 after activation; however, relatively little is known about the effect of CTLA-4-Ig on B cells. This study tested the impact of CTLA-4-Ig on human B cell responses.

Methods

Human blood B cells were purified from healthy donors and activated in the presence of CTLA-4-Ig or the L6-Ig control protein in vitro. RT-q-PCR and immunofluorescence staining were performed to detect activation marker expression. ELISA was conducted to measure cytokine secretion. The CD80/CD86 levels on the surface of the memory B cells in the blood of 18 patients with rheumatoid arthritis (RA) were detected using immunofluorescence staining.

Results

CTLA-4-Ig suppressed the expression of Staphylococcus aureus (SAC)-induced CD80, CD86, TNFA, and IL6 in human B cells at the transcriptional level. Furthermore, CTLA-4-Ig concomitantly decreased SAC-induced CD80/CD86 surface expression on and TNF-α and IL-6 secretion from B cells. On the other hand, T cell-dependent (TD) stimulation-induced B cell activation, proliferation, plasma cell differentiation, and antibody secretion were not affected by CTLA-4-Ig. As expected, TD stimulation-induced surface CD80 was hindered by CTLA-4-Ig. Notably, a blockade of CD80/CD86 on the surface of the memory B cells was observed in the patients with RA after abatacept (CTLA-4-Ig) treatment. In a portion of the RA patients, restoration of CD80/CD86 staining on the surface of the memory B was detected starting in the 3rd month of abatacept treatment. Interestingly, the surface levels of CD80/CD86 on the patients’ memory B cells positively correlated with disease activity.

Conclusions

We found that CTLA-4-Ig directly suppressed SAC-induced B cell activation in vitro. Obstruction of CD80 and CD86 on the surface of the memory B cells was detected in the RA patients after abatacept treatment. Blocking CD80/CD86 on B cells by CTLA-4-Ig may hinder T cell activation and associated with the disease activity of RA in vivo. Our findings indicate that CTLA-4-Ig may regulate humoral responses by modulating B cell activation and interfering T cell-B cell interaction.

Anti-rheumatoid arthritis effects of flavonoids from Daphne genkwa

OBJECTIVE

This study aims to select the most effective anti-Rheumatoid Arthritis (RA) component of flavonoids from Daphne genkwa Sieb. et Zucc. by anti-inflammatory and immunomodulatory effects in vitro, and to elucidate the mechanism.

METHODS

The anti-inflammatory and immunomodulatory effects of total flavonoids (TF) and four flavonoid components (genkwanin, hydroxygenkwanin, luteolin and apigenin) were determined by pharmacological approach in LPS-induced RAW 264.7 macrophages and ConA-induced T lymphocytes. Principal component analysis (PCA) was used to obtain the optimal anti-RA component in vitro. Western blot and real-time quantitative PCR (q-PCR) were used to explore the mechanisms. Finally, the in vitro anti-RA effect was verified by human rheumatoid arthritis fibroblast-like synoviocytes (FLSs).

RESULTS

TF and four flavonoids significantly reduced the expressions of NO, iNOS, TNF-α, IL-6, IFN-γ and IL-2. PCA showed that genkwanin was the most effective anti-RA component in vitro. Genkwanin inhibited nuclear factor-κB (NF-κB) pathway by decreasing the phosphorylation levels of IKK, IκB and NF-κB, and down-regulated the expressions of iNOS, COX-2 and IL-6 mRNA. Genkwanin also inhibited the abnormal proliferation of FLSs and down-regulated the secretions of NO and IL-6.

CONCLUSION

The most effective anti-RA component was genkwanin. Genkwanin exerts anti-RA effect through down-regulating the activation of NF-κB pathway and mRNA expressions of inflammatory mediators, and also by inhibiting the abnormal proliferation of FLSs and its NO and IL-6 secretion levels.

Immune checkpoint inhibitor-induced inflammatory arthritis as a model of autoimmune arthritis

The development of inflammatory arthritis in patients receiving immune checkpoint inhibitor therapy is increasingly recognized due to the growing use of these drugs for the treatment of cancer. This represents an important opportunity not only to define the mechanisms responsible for the development of this immune-related adverse event and to ultimately predict or prevent its development, but also to provide a unique window into early events in the development of inflammatory arthritis. Knowledge gained through the study of this patient population, for which the inciting event is known, could shed light into the pathogenesis of autoimmune arthritis. This review will highlight the clinical and immunologic features of these entities to define common elements for future study.

Safety and effectiveness of abatacept in systemic sclerosis: The EUSTAR experience

OBJECTIVE

To analyze the safety and effectiveness of abatacept (ABA) given in routine care to patients with systemic sclerosis (SSc).

METHODS

Retrospective multicenter observational study that enrolled patients with SSc treated with ABA. We collected epidemiological data and clinical outcomes. First, we analyzed the frequency of adverse effects. Secondly, we compared the evolution of different organ manifestations during ABA treatment. We collected data from 6 months before start of therapy to the last follow-up the following parameters: modified Rodnan Skin Score (mRSS), joints, lung and gastrointestinal involvement, concomitant medications, and laboratory tests.

RESULTS

Data on twenty-seven patients with SSc were collected (93% females; 67% limited SSc). Rheumatoid arthritis was the most frequent concomitant autoimmune disease. ILD was present in 15 patients. Anti-Scl 70 antibodies were present in 13 patients and rheumatoid factor and ACPA antibodies were present in eight and seven patients respectively. The main indication to use abatacept was joint involvement (59%) followed by myositis (26%). A total of 16 adverse effects were reported in 28 months of abatacept treatment including five that required hospitalization. Most of them occurred in the first 3 months after starting abatacept. After 12 months, the number of tender and swollen joints decreased compared to baseline (p<0.03 and p<0.02 respectively). Moreover, a beneficial effect of abatacept on HAQ-DI at 3 and 6 months (p<0.05) and on morning stiffness at 6 and 12 months (p<0.03) was observed. We also observed a decrease in the modified Rodnan skin score (p<0.05). No changes in lung or gastrointestinal involvement were found.

CONCLUSIONS

ABA demonstrated a good safety profile and seems to have some effectiveness on joint involvement and related disability in SSc patients treated in routine care.

CTLA-4: From mechanism to autoimmune therapy

CD28 and CTLA-4 are both important stimulatory receptors for the regulation of T cell activation. Because receptors share common ligands, B7.1 and B7.2, the expression and biological function of CTLA-4 is important for the negative regulation of T cell responses. Therefore, elimination of CTLA-4 can result in the breakdown of immune tolerance and the development of several diseases such as autoimmunity. Inhibitory signals of CTLA-4 suppress T cell responses and protect against autoimmune diseases in many ways. In this review, we summarize the structure, expression and signaling pathway of CTLA-4. We also highlight how CTLA-4 defends against potentially self-reactive T cells. Finally, we discuss how the CTLA-4 regulates a number of autoimmune diseases that indicate manipulation of this inhibitory molecule is a promise as a strategy for the immunotherapy of autoimmune diseases.

Tumour necrosis factor α augments the inhibitory effects of CTLA-4-Ig on osteoclast generation from human monocytes via induction of CD80 expression

Cytotoxic T lymphocyte antigen-4-immunoglobulin (CTLA-4-Ig) exerts anti-rheumatic action via negative regulation of the co-stimulation process between antigen-presenting cells and T cells. CTLA-4-Ig also binds to CD80/CD86 on monocytes of osteoclast precursors. However, little is known about the effect of CTLA-4-Ig on osteoclastogenesis in rheumatoid arthritis (RA). In this study we evaluated the effects of CTLA-4-Ig on osteoclast generation from human blood monocytes (PBM) and rheumatoid synovial fluid monocytes (RSFM). Highly purified monocytes were cultured with receptor activator of nuclear factor kappa-B ligand (RANKL) and macrophage colony-stimulating factor (M-CSF) in the presence of CTLA-4-Ig. CTLA-4-Ig inhibited RANKL-induced osteoclast generation in PBM and RSFM, as determined by tartrate-resistant acid phosphatase (TRAP) staining and bone resorption assay using osteo assay surface plates. In addition, CTLA-4-Ig reduced the gene and protein expressions of nuclear factor of activated T cells, cytoplasmic 1 (NFATc1) and cathepsin K during osteoclastogenesis. Furthermore, CTLA-4-Ig significantly inhibited cell proliferation during osteoclastogenesis. Interestingly, the gene expression of indoleamine 2,3-dioxygenase-1, an inducer of apoptosis, was enhanced by CTLA-4-Ig. We next examined the effect of tumour necrosis factor (TNF)-α, a major inflammatory cytokine in rheumatoid synovium, on the expression of CD80 and CD86 by flow cytometric analysis. TNF-α potently induced the surface expression of CD80, which is known to have much higher affinity to CTLA-4-Ig than CD86, and this induction was observed at mRNA levels. Interestingly, freshly prepared rheumatoid synovial monocytes also expressed CD80 as much as TNF-α-treated PBM. Furthermore, TNF-α enhanced CTLA-4-Ig-induced inhibition of osteoclastogenesis and cell proliferation. Taken together, the TNF-α-induced CD80 may augment CTLA-4-Ig-induced inhibition of osteoclastogenesis, suggesting that CTLA-4-Ig potently inhibits osteoclast differentiation and protects bone destruction in rheumatoid inflamed joints.

Effects of CTLA4-Ig treatment on circulating fibrocytes and skin fibroblasts from the same systemic sclerosis patients: an in vitro assay

Background

Systemic sclerosis (SSc) is characterized by vasculopathy and progressive fibrosis. CTLA4-Ig (abatacept) is able to interact with the cell surface costimulatory molecule CD86 and downregulate the target cell. The aim of this study was to evaluate the in-vitro effects of CTLA4-Ig treatment on circulating fibrocytes and skin fibroblasts isolated from the same SSc patient.

Methods

Circulating fibrocytes and skin fibroblasts were obtained from eight SSc patients with “limited” cutaneous involvement and from four healthy subjects (HSs). Samples were analyzed by fluorescence-activated cell sorter analysis (FACS) at baseline (T0) and after 8 days of culture (T8) for CD45, collagen type I (COL I), CXCR4, CD14, CD86, and HLA-DRII expression. Circulating fibrocytes were treated for 3 h and skin fibroblasts for 24/48 h with CTLA4-Ig (10, 50, 100, 500 μg/ml). Quantitative real-time polymerase chain reaction (qRT-PCR) was performed for CD86, COL I, FN, TGFβ, αSMA, S100A4, CXCR2, CXCR4, CD11a, and Western blotting was performed for COL I and FN.

Results

Using qRT-PCR, the T8-cultured SSc circulating fibrocytes which had not been treated with CTLA4-Ig showed higher gene expression for CD86, αSMA, S100A4, TGFβ, and COL I compared with HS circulating fibrocytes. Interestingly, αSMA/COL I gene expression was significantly lower only in the SSc circulating fibrocytes treated with CTLA4-Ig for 3 h (p < 0.01, p < 0.05). On the contrary, no effects were observed for either SSc or HS skin fibroblasts after CTLA4-Ig treatment. COL I and FN protein expression was unchanged in both SSc and HS skin fibroblasts by Western blot.

Conclusions

Circulating fibrocytes seem to be more responsive to CTLA4-Ig treatment than skin fibroblasts from the same SSc patient, likely due to their higher expression of CD86. CTLA4-Ig treatment might downregulate the fibrotic process in SSc patients by downregulating the fibrocytes, circulating progenitor cells.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1652-6) contains supplementary material, which is available to authorized users.

The Effect of Immunosuppressive Drugs on MDSCs in Transplantation

Myeloid-derived suppressor cells (MDSCs) are a group of innate immune cells that regulates both innate and adaptive immune responses. In recent years, MDSCs were shown to play an important negative regulatory role in transplant immunology even upstream of regulatory T cells. In certain cases, MDSCs are closely involved in transplantation immune tolerance induction and maintenance. It is known that some immunosuppressant drugs negatively regulate MDSCs but others have positive effects on MDSCs in different transplant cases. We herein summarized our recent insights into the regulatory roles of MDSCs in transplantation specially focusing on the effects of immunosuppressive drugs on MDSCs and their mechanisms of action. Studies on the effects of immunosuppressive drugs on MDSCs will significantly expand our understanding of immunosuppressive drugs on immune regulatory cells in transplantation and offer new insights into transplant tolerance. We hope to emphasize our concern for the negative effects of immunosuppressive agents on MDSCs, which may potentially attenuate the immune tolerance induction in transplanted recipients.

Abatacept in the treatment of psoriatic arthritis: biological and clinical profiles of the responders

Abatacept (CTLA4Ig), a selective T-cell costimulation modulator, has been approved for the treatment of psoriatic arthritis patients with an inadequate response to conventional synthetic disease-modifying antirheumatic drugs, but not for those with uncontrolled skin lesions, nor with axial involvement. In this review, we will try to interpret such a differential efficacy of abatacept on the psoriatic arthritis clinical domains, on the basis of its differential effectiveness on the diverse T-cell subsets at different sites. Clinical and biological profiles of possible responders to abatacept will be provided.

Abatacept blocks anti-citrullinated protein antibody and rheumatoid factor mediated cytokine production in human macrophages in IDO-dependent manner

Background

The anti-inflammatory effect of abatacept is most pronounced in patients with high-titer autoantibodies (including anticitrullinated protein antibodies [ACPA] and rheumatoid factor [RF]). Considering that autoantibodies trigger inflammatory cytokine production by monocytes and that abatacept binds to monocytes, influencing their functional state, we hypothesized that abatacept may effectively inhibit the production of several different cytokines by ACPA- or RF-challenged monocytes.

Methods

Peripheral blood CD68⁺ monocytes stimulated with macrophage colony-stimulating factor for 24 h were exposed to random immunoglobulin G alone (negative control), purified ACPA, purified RF, or lipopolysaccharide (positive control) in cell culture plates coated with citrullinated vimentin (to allow ACPA immune complex formation). Stimulations were done in the presence or absence of abatacept or tumor necrosis factor (TNF) antibody (adalimumab) with or without indoleamine 2,3-dioxygenase (IDO) inhibitor 1-methyl-d-tryptophan. Supernatants were analyzed for key proinflammatory cytokines TNF-α, interleukin (IL)-1β, IL-6, IL-8, and chemokine (C-C motif) ligand 2 (CCL2) after 24 h.

Results

Exposure to ACPA or RF significantly induced the production of TNF-α (20-fold and 27-fold, respectively), IL-1β (each 4-fold), IL-6 (12-fold and 11-fold, respectively), IL-8 (43-fold and 30-fold, respectively), and CCL2 (each 4-fold) in human monocytes. Abatacept inhibited this autoantibody-mediated upregulation of cytokines, reducing TNF-α by > 75%, IL-1β by > 65%, IL-6 and IL-8 by > 80%, and CCL2 by > 60%. In contrast, a TNF inhibitor did not influence autoantibody-induced proinflammatory cytokine production. IDO inhibition reversed the effect of abatacept and again permitted the induction of cytokine production by ACPA and RF.

Conclusions

These data show that abatacept interferes with autoantibody-mediated cytokine production by monocytes through induction of IDO. This inhibitory effect on the production of several effector cytokines in RA may explain the fast anti-inflammatory effect of abatacept as well as its preferential efficacy in patients with high-titer ACPA and RF.

Immunotherapy for cardiovascular disease

Heart failure (HF), the final stage of pathological cardiac hypertrophy, is a major cause of hospitalization and mortality. The role of inflammation in the pathogenesis of HF has been extensively studied, with great emphasis on proinflammatory cytokines. Yet, clinical trials targeting these cytokines failed to become a credible therapeutic strategy for HF. More recent studies are increasingly highlighting an active role for T cells in the progression of HF pathology. As a result, a number of novel immunotherapy strategies are emerging for the treatment of HF and other cardiovascular diseases, via the targeting of adaptive immunity. Here we provide an overview of the background, details, and expected outcomes of these attempts.

Genome-Wide Association Meta-Analysis Reveals Novel Juvenile Idiopathic Arthritis Susceptibility Loci

OBJECTIVE

Juvenile idiopathic arthritis (JIA) is the most common childhood rheumatic disease and has a strong genomic component. To date, JIA genetic association studies have had limited sample sizes, used heterogeneous patient populations, or included only candidate regions. The aim of this study was to identify new associations between JIA patients with oligoarticular disease and those with IgM rheumatoid factor (RF)-negative polyarticular disease, which are clinically similar and the most prevalent JIA disease subtypes.

METHODS

Three cohorts comprising 2,751 patients with oligoarticular or RF-negative polyarticular JIA were genotyped using the Affymetrix Genome-Wide SNP Array 6.0 or the Illumina HumanCoreExome-12+ Array. Overall, 15,886 local and out-of-study controls, typed on these platforms or the Illumina HumanOmni2.5, were used for association analyses. High-quality single-nucleotide polymorphisms (SNPs) were used for imputation to 1000 Genomes prior to SNP association analysis.

RESULTS

Meta-analysis showed evidence of association (P < 1 × 10^-6 ) at 9 regions: PRR9_LOR (P = 5.12 × 10^-8 ), ILDR1_CD86 (P = 6.73 × 10^-8 ), WDFY4 (P = 1.79 × 10^-7 ), PTH1R (P = 1.87 × 10^-7 ), RNF215 (P = 3.09 × 10^-7 ), AHI1_LINC00271 (P = 3.48 × 10^-7 ), JAK1 (P = 4.18 × 10^-7 ), LINC00951 (P = 5.80 × 10^-7 ), and HBP1 (P = 7.29 × 10^-7 ). Of these, PRR9_LOR, ILDR1_CD86, RNF215, LINC00951, and HBP1 were shown, for the first time, to be autoimmune disease susceptibility loci. Furthermore, associated SNPs included cis expression quantitative trait loci for WDFY4, CCDC12, MTP18, SF3A1, AHI1, COG5, HBP1, and GPR22.

CONCLUSION

This study provides evidence of both unique JIA risk loci and risk loci overlapping between JIA and other autoimmune diseases. These newly associated SNPs are shown to influence gene expression, and their bounding regions tie into molecular pathways of immunologic relevance. Thus, they likely represent regions that contribute to the pathology of oligoarticular JIA and RF-negative polyarticular JIA.

T cell costimulation blockade blunts pressure overload-induced heart failure

Heart failure (HF) is a leading cause of mortality. Inflammation is implicated in HF, yet clinical trials targeting pro-inflammatory cytokines in HF were unsuccessful, possibly due to redundant functions of individual cytokines. Searching for better cardiac inflammation targets, here we link T cells with HF development in a mouse model of pathological cardiac hypertrophy and in human HF patients. T cell costimulation blockade, through FDA-approved rheumatoid arthritis drug abatacept, leads to highly significant delay in progression and decreased severity of cardiac dysfunction in the mouse HF model. The therapeutic effect occurs via inhibition of activation and cardiac infiltration of T cells and macrophages, leading to reduced cardiomyocyte death. Abatacept treatment also induces production of anti-inflammatory cytokine interleukin-10 (IL-10). IL-10-deficient mice are refractive to treatment, while protection could be rescued by transfer of IL-10-sufficient B cells. These results suggest that T cell costimulation blockade might be therapeutically exploited to treat HF.

Abatacept is an FDA-approved drug used for treatment of rheumatoid arthritis. Here the authors show that abatacept reduces cardiomyocyte death in a mouse model of heart failure by inhibiting activation and heart infiltration of T cells and macrophages, an effect mediated by IL-10, suggesting a potential therapy for heart failure.

Therapy with CTLA4-Ig and an antiviral monoclonal antibody controls chikungunya virus arthritis

In 2013, chikungunya virus (CHIKV) transmission was documented in the Western Hemisphere, and the virus has since spread throughout the Americas with more than 1.8 million people infected in more than 40 countries. CHIKV targets the joints, resulting in symmetric polyarthritis that clinically mimics rheumatoid arthritis and can endure for months to years. At present, no approved treatment is effective in preventing or controlling CHIKV infection or disease. We treated mice with eight different disease-modifying antirheumatic drugs and identified CLTA4-Ig (abatacept) and tofacitinib as candidate therapies based on their ability to decrease acute joint swelling. CTLA4-Ig reduced T cell accumulation in the joints of infected animals without affecting viral infection. Whereas monotherapy with CTLA4-Ig or a neutralizing anti-CHIKV human monoclonal antibody provided partial clinical improvement, therapy with both abolished swelling and markedly reduced levels of chemokines, proinflammatory cytokines, and infiltrating leukocytes. Thus, combination CTLA4-Ig and antiviral antibody therapy controls acute CHIKV infection and arthritis and may be a candidate for testing in humans.

Cytotoxic T-lymphocyte-associated protein 4 gene polymorphism is related to rheumatoid arthritis in Egyptian population

CONTEXT

Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) is a CD28-family receptor expressed on T-cells which suppresses T cell proliferation. CTLA-4 -318C/T polymorphism is involved in regulation of CTLA-4 expression.

OBJECTIVE

The study aimed to investigate the genetic association of CTLA-4 -318C/T polymorphism with rheumatoid arthritis (RA) and the activity and severity of the disease in the Egyptian population.

METHODS

A single nucleotide polymorphism (rs5742909) in CTLA-4 was genotyped in 100 RA patients and 100 healthy controls using polymerase chain reaction-restriction fragment length polymorphism. Diagnostic tests were measured for RA patients.

RESULTS

The frequency of T allele in RA patients was significantly higher than in the control subjects (p = 0.002). CT and TT genotypes had high C-reactive protein, erythrocyte sedimentation rate and disease activity score 28 while CC genotype had a high rheumatoid factor.

CONCLUSION

A minor allele of CTLA-4 rs5742909 polymorphism was associated with RA and the activity but not the severity of the disease.

Treatment with abatacept prevents experimental dermal fibrosis and induces regression of established inflammation-driven fibrosis

OBJECTIVE

Activated T cells are the main component of the inflammatory skin infiltrates that characterise systemic sclerosis (SSc). Our aim was to investigate the efficacy of abatacept, which tempers T-cell activation, in reducing skin fibrosis in complementary mouse models of SSc.

METHODS

The antifibrotic properties of abatacept were evaluated in the mouse models of bleomycin-induced dermal fibrosis and sclerodermatous chronic graft-versus-host disease, reflecting early and inflammatory stages of SSc. Thereafter, we studied the efficacy of abatacept in tight skin (Tsk-1) mice, an inflammation-independent mouse model of skin fibrosis.

RESULTS

Abatacept efficiently prevented bleomycin-induced skin fibrosis and was also effective in the treatment of established fibrosis. In this model, abatacept decreased total and activated T-cell, B-cell and monocyte infiltration in the lesional skin. Abatacept did not protect CB17-SCID mice from the development of bleomycin-induced dermal fibrosis, which supports that T cells are necessary to drive the antifibrotic effects of abatacept. Upon bleomycin injections, skin interleukin (IL) 6 and IL-10 levels were significantly reduced upon abatacept treatment. Moreover, treatment with abatacept ameliorated fibrosis in the chronic graft-versus-host disease model, but demonstrated no efficacy in Tsk-1 mice. The tolerance of abatacept was excellent in the three mouse models.

CONCLUSIONS

Using complementary models, we demonstrate that inhibition of T-cell activation by abatacept can prevent and induce the regression of inflammation-driven dermal fibrosis. Translation to human disease is now required, and targeting early and inflammatory stages of SSc sounds the most appropriate for positioning abatacept in SSc.

New pharmacological strategies in rheumatic diseases

Targeting the pathogenic pathway of chronic inflammation represents an unmet challenge for controlling disease activity, preventing functional disability, and maintaining an adequate quality of life in patients with rheumatic diseases. Abatacept, a novel molecule that inhibits co-stimulation signal, induces an inhibitory effect on the T-cells. This will further interfere with the activity of several cell lines, leading to the normalization of the immune response. In the latest years, abatacept has been extensively investigated in studies of rheumatoid arthritis for which it was recently approved as a second line biologic treatment in Romania. This review presents the clinical efficacy of abatacept in several rheumatic diseases and highlights the safety profile of this biological agent. Abbreviations: ACR = American College of Rheumatology, ADR = Adverse drug reaction, APC = antigen presenting cell, ApS = psoriatic arthritis, CRP = C reactive protein, CTLA-4 = Cytotoxic T-Cell Lymphocyte Antigen-4, DAS = Disease activity score, DMARDs = Disease modifying antirheumatic drugs, EMA = European Medicine Agency, EULAR = European League Against Rheumatism, FDA = Food and Drugs Administration, HBV = Hepatitis B virus, JIA = Juvenile Idiopathic Arthritis, LDA = low disease activity (LDA), MRI = magnetic resonance imaging (MRI), MTX = methotrexate, RA = rheumatoid arthritis, RCT = randomized controlled trial, SS = Sjogren's syndrome, TCR = T cell receptor.

Abatacept decreases disease activity in a absence of CD4(+) T cells in a collagen-induced arthritis model

Introduction

Abatacept is a fusion protein of human cytotoxic T-lymphocyte–associated protein (CTLA)-4 and the Fc portion of human immunoglobulin G1 (IgG1). It is believed to be effective in the treatment of rheumatoid arthritis by inhibiting costimulation of T cells via blocking CD28–B7 interactions as CTLA-4 binds to both B7.1 (CD80) and B7.2 (CD86). However, the interaction of CD28 with B7 molecules is crucial for activation of naive cells, whereas it is unclear whether the action of already activated CD4⁺ T cells, which are readily present in established disease, also depends on this interaction. The aim of this study was to determine whether the mode of action of abatacept depends solely on its ability to halt T cell activation in established disease.

Methods

Arthritis was induced in thymectomized male DBA/1 mice by immunisation with bovine collagen type II. The mice were subsequently depleted for CD4⁺ T cells. Abatacept or control treatment was started when 80 % of the mice showed signs of arthritis. Arthritis severity was monitored by clinical scoring of the paws, and anti-collagen antibody levels over time were determined by enzyme-linked immunosorbent assay.

Results

Treatment with abatacept in the absence of CD4⁺ T cells resulted in lower disease activity. This was associated with decreasing levels of collagen-specific IgG1 and IgG2a antibodies, whereas the antibody levels in control or CD4⁺ T cell–depleted mice increased over time.

Conclusions

These results show that abatacept decreased disease activity in the absence of CD4⁺ T cells, indicating that the mode of action of abatacept in established arthritis does not depend entirely on its effects on CD4⁺ T cell activation.

Targeting the CD80/CD86 costimulatory pathway with CTLA4-Ig directs microglia toward a repair phenotype and promotes axonal outgrowth

Among the costimulatory factors widely studied in the immune system is the CD28/cytotoxic T-lymphocyte antigen-4 (CTLA4)-CD80/CD86 pathway, which critically controls the nature and duration of the T-cell response. In the brain, up-regulated expression of CD80/CD86 during inflammation has consistently been reported in microglia. However, the role of CD80/CD86 molecules has mainly been studied in a context of microglia-T cell interactions in pathological conditions, while the function of CD80/CD86 in the regulation of intrinsic brain cells remains largely unknown. In this study, we used a transgenic pig line in which neurons express releasable CTLA4-Ig, a synthetic molecule mimicking CTLA4 and binding to CD80/CD86. The effects of CTLA4-Ig on brain cells were analyzed after intracerebral transplantation of CTLA4-Ig-expressing neurons or wild-type neurons as control. This model provided in vivo evidence that CTLA4-Ig stimulated axonal outgrowth, in correlation with a shift of the nearby microglia from a compact to a ramified morphology. In a culture system, we found that the CTLA4-Ig-induced morphological change of microglia was mediated through CD86, but not CD80. This was accompanied by microglial up-regulated expression of the anti-inflammatory molecule Arginase 1 and the neurotrophic factor BDNF, in an astrocyte-dependent manner through the purinergic P2Y1 receptor pathway. Our study identifies for the first time CD86 as a key player in the modulation of microglia phenotype and suggests that CTLA4-Ig-derived compounds might represent new tools to manipulate CNS microglia.

Specific therapy to regulate inflammation in rheumatoid arthritis: molecular aspects

Rheumatoid arthritis (RA) is a chronic inflammatory disease in which persistent inflammation of synovial tissue results in a progressive functional decline of the joint and premature mortality. TNF inhibitors were the first biological disease-modifying antirheumatic drugs (DMARDs) used to treat RA. Since then, new biological drugs have emerged, such as inhibitors of IL-1, IL-6 and others, with different mechanisms of action that include the depletion of B cells and the inhibition of T-cell costimulation. Recently, RA treatments have incorporated the use of synthetic DMARDs. This review describes the molecular aspects of the mechanisms of action of biological and synthetic DMARDs, discusses the adverse effects and limitations of established therapies and analyses the alternative approaches to RA treatment.

CTLA4-Ig (abatacept) therapy modulates T cell effector functions in autoantibody-positive rheumatoid arthritis patients

Background

Rheumatoid arthritis is a chronic inflammatory disease with a strong MHC class II component and where many patients develop characteristic autoantibodies towards the noncoding amino acid citrulline. Such anti-citrullinated protein antibodies (ACPA) have recently been put forward as an independent predictive factor for treatment response by co-stimulation blockade by CTLA4-Ig (abatacept). We have performed a mechanism of action study to dissect T cell functionality in RA patients with long-standing disease undergoing abatacept treatment and the influence of ACPA status.

Results

Peripheral blood samples were collected from RA patients as they started CTLA4-Ig treatment and 3 and 6 months later. A general decrease of regulatory T cell subsets was observed in the cohort. Additionally within the ACPA-positive group significant down-regulation of all key T cell effector subsets including Th1, Th2, and Th17 was observed by analyzing cytokines by intracellular flow cytometry and in cell culture supernatants.

RA synovial fluid samples were cultured in vitro in the presence or absence of CTLA4-Ig (abatacept). T cell cytokine production was diminished, but without increasing the functional capacity of CD4+CD25hi regulatory T cells as previously demonstrated in the context of TNF-blockade and anti-IL6R therapy.

Conclusions

Our immunological study of T cell functionality in RA patients, both ACPA-positive and ACPA-negative, starting biological therapy with the co-stimulation blockade abatacept (CTLA4-Ig) supports the recently published registry study implicating ACPA seropositivity as an independent predictive factor to treatment response as we observed the most striking effect on T cell subset modulation in ACPA-positive patients. These data further support the notion of RA as a disease with several sub-entities, where the ACPA-positive fraction represents a classical HLA-associated autoimmune disorder while ACPA-negative patients may have other driving forces apart from classical adaptive immune responses.

Advances in CTLA-4-Ig-mediated modulation of inflammatory cell and immune response activation in rheumatoid arthritis

Rheumatoid arthritis (RA) is a multifactorial and polygenic immune-mediated disease, the pathogenesis of which involves different cell types. T and B lymphocytes, macrophages, endothelial cells, fibroblasts and osteoclasts have all been implicated in mediating the production of autoantibodies, proinflammatory cytokines and ultimately bone erosions. Cytotoxic T lymphocyte-associated antigen 4 immunoglobulin fusion protein (CTLA-4-Ig, abatacept) is a unique biologic agent targeting the co-stimulatory molecules CD80/CD86, and is indicated for the treatment of moderate-to-severe RA in patients who have had an inadequate response to one or more disease-modifying anti-rheumatic drugs, including methotrexate or anti-tumor necrosis factor agents. There is a growing body of evidence that, through selective modulation of the CD80/CD86 co-stimulatory molecules expressed by a variety of activated cell types, CTLA-4-Ig may inhibit the pathogenic RA process at several levels, both directly and indirectly. Here, we provide an overview of recent mechanistic studies of the action of CTLA-4-Ig on different cell types involved in mediating inflammation and joint damage in RA.

Dendritic cells: novel players in fibrosis and scleroderma

Dendritic cells are professional antigen-presenting cells that are most studied for their function in mediating T-cell tolerance and T-cell activation. In addition, recent evidence indicates that dendritic cells can regulate the vasculature and function of fibroblast-type cells. The potential contribution of dendritic cells to scleroderma and fibrosis is not well-understood. In this article, we review recent studies as well as describe our own ongoing work that points toward a role for dendritic cells in scleroderma and fibrosis.

Network-based gene expression biomarkers for cold and heat patterns of rheumatoid arthritis in traditional chinese medicine

In Traditional Chinese Medicine (TCM), patients with Rheumatoid Arthritis (RA) can be classified into two main patterns: cold-pattern and heat-pattern. This paper identified the network-based gene expression biomarkers for both cold- and heat-patterns of RA. Gene expression profilings of CD4+ T cells from cold-pattern RA patients, heat-pattern RA patients, and healthy volunteers were obtained using microarray. The differentially expressed genes and related networks were explored using DAVID, GeneSpring software, and the protein-protein interactions (PPI) method. EIF4A2, CCNT1, and IL7R, which were related to the up-regulation of cell proliferation and the Jak-STAT cascade, were significant gene biomarkers of the TCM cold pattern of RA. PRKAA1, HSPA8, and LSM6, which were related to fatty acid metabolism and the I-κB kinase/NF-κB cascade, were significant biomarkers of the TCM heat-pattern of RA. The network-based gene expression biomarkers for the TCM cold- and heat-patterns may be helpful for the further stratification of RA patients when deciding on interventions or clinical trials.

Abatacept and sodium thiosulfate for treatment of recalcitrant juvenile dermatomyositis complicated by ulceration and calcinosis

We report the successful use of abatacept and sodium thiosulfate in a patient with severe recalcitrant juvenile dermatomyositis complicated by ulcerative skin disease and progressive calcinosis. This combination therapy resulted in significant reductions in muscle and skin inflammation, decreased corticosteroid dependence, and halted the progression of calcinosis.

Local delivery of AAV2-CTLA4IgG decreases sialadenitis and improves gland function in the C57BL/6.NOD-Aec1Aec2 mouse model of Sjögren's syndrome

INTRODUCTION

Cytotoxic T-lymphocyte antigen 4 (CTLA-4) is a key negative costimulatory molecule that displays a wide range of anti-inflammatory properties and is currently approved to treat rheumatoid arthritis as a recombinant fusion protein (CTLA4IgG). To better understand the role of CTLA4IgG in primary Sjögren's syndrome (pSS), we generated a recombinant adeno-associated virus vector serotype 2 (AAV2) expressing a chimera of mouse CTLA-4 fused with a human immunoglobulin (AAV2-CTLA4IgG) and observed the effect of this molecule in C57BL/6.NOD-Aec1Aec2 mice, an animal model of pSS.

METHODS

A recombinant adeno-associated virus-2 (AAV-2) vector was constructed encoding a CTLA4IgG fusion protein. The AAV2-CTLA4IgG vector and an AAV2 control vector encoding beta galactosidase (LacZ) were administered by retrograde cannulation of the submandibular glands of C57BL/6.NOD-Aec1Aec2 mice. Protein expression was measured by ELISA and salivary glands were assessed for inflammation and activity.

RESULTS

Recombinant CTLA4IgG blocked B7 expression on macrophages in vitro. In vivo, localized expression of CTLA4IgG in the salivary glands of C57BL/6.NOD-Aec1Aec2 mice inhibited the loss of salivary gland activity and decreased T and B cell infiltration as well as dendritic cells and macrophages in the glands compared with control mice. In addition a decrease in several proinflammatory cytokines and an increase in transforming growth factor beta-1 (TGF-β1) expression were also observed.

CONCLUSIONS

These data suggest expression of CTLA4IgG in the salivary gland can decrease the inflammation and improve the xerostomia reported in these mice.