Abatacept (CTLA-4IG) treatment reduces the migratory capacity of monocytes in patients with rheumatoid arthritis

Cytotoxic T-Lymphocyte-Associated Protein 4 Fused to a Modified Fragment of IgG1 Reduces Muscle Fiber Damage in a Model of Duchenne Muscular Dystrophy by Attenuating Proinflammatory Gene Expression in Myeloid Lineage Cells

Duchenne muscular dystrophy (DMD) is a lethal, muscle-wasting, genetic disease that is greatly amplified by an immune response to the diseased muscles. The mdx mouse model of DMD was used to test whether the pathology can be reduced by treatments with a cytotoxic T-lymphocyte-associated protein 4 fused to a modified fragment of IgG1 (CTLA4-Ig) fusion protein that blocks costimulatory signals required for activation of T cells. CTLA4-Ig treatments reduced mdx sarcolemma lesions and reduced the numbers of activated T cells, macrophages, and antigen-presenting cells in mdx muscle and reduced macrophage invasion into muscle fibers. In vitro data showed that CTLA4-Ig acts directly on bone marrow cells and macrophages to modify their function and gene expression. CTLA4-Ig treatments of mdx bone marrow cells diminished their mobility and chemotactic response to chemokine ligand-2. Treating mdx macrophages with CTLA4-Ig reduced their cytolysis of muscle cells in vitro. RNA-sequencing analysis of mdx macrophages showed that CTLA4-Ig reduced expression of genes associated with leukocyte chemotaxis, migration, and extravasation; >90% of those affected genes were tumor necrosis factor-α target genes. Comparison of mdx and wild-type macrophages by RNA sequencing showed that 46% of the genes down-regulated by CTLA4-Ig were genes up-regulated in macrophages by the presence of muscular dystrophy in mice. These findings show that CTLA4-Ig is a promising immunotherapeutic for DMD, and many of its beneficial effects may result from direct actions on macrophages that modify their expression of proinflammatory genes.

CD20 + cells blockage by rituximab delays wound healing in oral traumatic ulcers in rats

OBJECTIVE

Wound healing of oral traumatic ulcers (OTU) is strongly associated with cytokines and inflammatory cells, and the reduction of anti-inflammatory cells, such as lymphocyte B, may interfere with OTU repair. We aimed to evaluate the role of CD20 + cells in the healing process of OTU in rats.

DESIGN

Wistar male rats were divided into four groups: a control group (treated with 0.1 mL/kg of saline) and three groups treated with anti-CD20 rituximab (RTX) at 2.5, 10, or 40 mg/kg 24 h before OTU production. The animals were weighed (day 0) and euthanized on days 3, 7, 14, and 21 after ulceration. With Blood cells (hematological analysis) and the traumatically induced ulcers were clinically measured. The mucosal samples were histologically (scores 0-4), histochemically (collagen assay (picrosirius)), histomorphometrically (cell counting), and immunohistochemically (CD20+, Tumor Necrosis Factor alpha(TNF-α), Interleukin(IL)- 1β, IL-6 and α-smooth-muscle-actin (α-SMA)) analyzed. ANOVA-1-2-way/Bonferroni, Kruskal-Wallis/Dunn, and correlation analyses were performed (GraphPad Prism 5.0, p < 0.05).

RESULTS

RTX leads to leukopenia, lymphocytopenia, and neutropenia (p < 0.001), and high doses reduced the OTU area (p = 0.001), impaired histologic scores (p < 0.05), and delayed polymorphonuclear (p < 0.001) and mononuclear (p < 0.001) cells, and total (p = 0.011), type-I (p = 0.008), and type-III (p = 0.021) collagen.

CONCLUSION

RTX treatment reduced CD20+ cells in OTU (p = 0.001), TNF-α (p = 0.006), and α-SMA (p = 0.022) immunostaining and delayed IL-6 reduction (p = 0.006), with no influence in IL-1β immunostaining. CD20 + cell blockage by RTX reduced cell migration, acute inflammation, and wound healing in OTU.

Circulating and Synovial Monocytes in Arthritis and Ex-Vivo Model to Evaluate Therapeutic Modulation of Synovial Monocytes

Monocytes are innate immune cells that play a dual role in protection of host against pathogens and initiation and perpetuation of inflammatory disorders including joint diseases. During inflammation, monocytes migrate from peripheral blood to tissues via chemokine receptors where they produce inflammatory factors. Monocytes are classified into three subsets, namely: classical, intermediate and non-classical, each subset has particular function. Synovium of patients with inflammatory joint diseases, such as rheumatoid arthritis and psoriatic arthritis as well as osteoarthritis, is enriched by monocytes that differ from circulatory ones by distinct subsets distribution. Several therapeutic agents used systemically or locally through intra-articular injections in arthritis management modulate monocyte subsets. This scoping review summarized the existing literature delineating the effect of common therapeutic agents used in arthritis management on circulating and synovial monocytes/macrophages. As certain agents have an inhibitory effect on monocytes, we propose to test their potential to inhibit synovial monocytes via an ex-vivo platform based on cultured synovial fluid mononuclear cells derived from patients with rheumatic diseases. Information obtained from the ex-vivo platform can be applied to explore the therapeutic potential of medications in clinical practice.

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.

Attenuation of the severity and changes in the microbiota in an animal model of primary biliary cholangitis by FOXP3− regulatory T cells

Background

Primary biliary cholangitis (PBC), an autoimmune liver disease, presents with progressive damage to the intrahepatic bile ducts with infiltrating mononuclear cells and the appearance of anti‐mitochondrial antibodies (AMAs). The initiation of autoimmune liver disease is permissively mediated by dysfunctional regulatory T cells (Treg cells). Naïve CD4+ T cells cultured with splenic B220+ cells without additional cytokines or chemicals can differentiate into specific types of Treg cells (Treg/B cells) without expressing forkhead box P3. In this study, we explored the effects of Treg/B cells on disease severity and changes in intestinal microbiota in a murine model of PBC.

Methods

Treg/B cells were administered to 2‐octenoic acid‐induced PBC mice. Enzyme‐linked immunosorbent assay, flow cytometry and histopathological techniques were used to evaluate the severity of PBC and to assess its therapeutic effect. Diversity of the intestinal microbiota was determined using 16S rRNA sequencing. The suppressive mechanisms of Treg/B cells were investigated using the bone marrow‐derived dendritic cells (BMDCs).

Results

Treg/B‐cell treatment significantly decreased the levels of serum AMAs against pyruvate dehydrogenase complex E2, lowered the levels of serum bile acids, attenuated inflammatory cell infiltration, reduced dendritic cell activation, altered the population of T cells in the liver and alleviated liver collagen synthesis in PBC mice. In addition, the Treg/B‐cell treatment changed the faecal microbial diversity in PBC mice. Furthermore, Treg/B‐cell treatment decreased the levels of proinflammatory cytokines and expression of costimulatory molecules in BMDCs. This inhibitory effect was partially mediated by the cytotoxic T‐lymphocyte‐associated antigen 4 pathway.

Conclusion

Treatment with Treg/B cells in a murine model of PBC attenuated liver inflammation and altered the gut microbiota. Immune regulation of Treg/B cells may be a potential therapeutic strategy for treating autoimmune liver disease.

Serum cytokines and bone metabolic markers in patients with rheumatoid arthritis treated with biological disease modifying anti-rheumatic drugs

INTRODUCTION

/objectives Several biological disease-modifying anti-rheumatic drugs (bDMARDs) have been widely used for the management of rheumatoid arthritis (RA). These drugs target different molecules important for the pathophysiology of RA; however, only a few studies have compared the effects of these biological drugs on cytokines and bone metabolic markers. The main aim of this study is to clarify the effects of bDMARDs with different modes of action on the cytokine and bone metabolic marker levels in patients with RA.

METHODS

Patients with RA who were initiated on infliximab, tocilizumab, or abatacept as the first bDMARD were prospectively enrolled in this study. Serum cytokine and bone metabolic marker levels were measured longitudinally, and changes in their levels were compared.

RESULTS

A total of 174 patients were enrolled in this study, with 55, 70, and 49 patients in the infliximab, tocilizumab, and abatacept groups, respectively. At six months, despite the similar clinical effectiveness of the three drugs, changes in the cytokine and bone metabolic marker levels were distinct; interferon-γ and tumor necrosis factor-α levels were significantly increased with infliximab, interleukin-6 levels were increased with tocilizumab, and interleukin-1β and interleukin-8 levels were increased with abatacept treatment. Bone-specific alkaline phosphatase and osteocalcin levels increased more significantly with tocilizumab than with infliximab, while osteopontin and osteonectin levels decreased with infliximab treatment.

CONCLUSIONS

bDMARDs with different modes of action exert different effects on the cytokine and bone metabolic marker levels in patients with RA.

A lesion-selective albumin-CTLA4Ig as a safe and effective treatment for collagen-induced arthritis

BACKGROUND

CTLA4Ig is a dimeric fusion protein of the extracellular domain of cytotoxic T-lymphocyte protein 4 (CTLA4) and an Fc (Ig) fragment of human IgG₁ that is approved for treating rheumatoid arthritis. However, CTLA4Ig may induce adverse effects. Developing a lesion-selective variant of CTLA4Ig may improve safety while maintaining the efficacy of the treatment.

METHODS

We linked albumin to the N-terminus of CTLA4Ig (termed Alb-CTLA4Ig) via a substrate sequence of matrix metalloproteinase (MMP). The binding activities and the biological activities of Alb-CTLA4Ig before and after MMP digestion were analyzed by a cell-based ELISA and an in vitro Jurkat T cell activation assay. The efficacy and safety of Alb-CTLA4Ig in treating joint inflammation were tested in mouse collagen-induced arthritis.

RESULTS

Alb-CTLA4Ig is stable and inactive under physiological conditions but can be fully activated by MMPs. The binding activity of nondigested Alb-CTLA4Ig was at least 10,000-fold weaker than that of MMP-digested Alb-CTLA4Ig. Nondigested Alb-CTLA4Ig was unable to inhibit Jurkat T cell activation, whereas MMP-digested Alb-CTLA4Ig was as potent as conventional CTLA4Ig in inhibiting the T cells. Alb-CTLA4Ig was converted to CTLA4Ig in the inflamed joints to treat mouse collagen-induced arthritis, showing similar efficacy to that of conventional CTLA4Ig. In contrast to conventional CTLA4Ig, Alb-CTLA4Ig did not inhibit the antimicrobial responses in the spleens of the treated mice.

CONCLUSIONS

Our study indicates that Alb-CTLA4Ig can be activated by MMPs to suppress tissue inflammation in situ. Thus, Alb-CTLA4Ig is a safe and effective treatment for collagen-induced arthritis in mice.

CTLA-4-Ig internalizes CD80 in fibroblast-like synoviocytes from chronic inflammatory arthritis mouse model

CD80 interact with CD28 and CTLA-4 on antigen-presenting cells, and function in the co-stimulatory signaling that regulates T cell activity. CTLA-4-Ig is used to treat RA by blocking co-stimulatory signaling. Chronic inflammatory arthritis was induced in D1BC mice using low-dose arthritogenic antigens and treated with CTLA-4-Ig. We performed histopathology of the joints and lymph nodes, serological examination for rheumatoid factors, and flow cytometric analysis of isolated synovial cells, including CD45- FLSs and CD45+ synovial macrophages. CTLA-4-Ig treatment ameliorated the chronic inflammatory polyarthritis. There was a decrease in the number of infiltrating lymphoid cells in the joints as well as in the levels of RF-IgG associated with a decrease in the number of B cells in the lymph nodes; more than 15% of CD45- FLSs expressed CD80, and a small number of them expressed PD-L1, indicating the presence of PD-L1/CD80 cis-heterodimers in these cells. CTLA-4-Ig internalized CD80, but not PD-L1, in isolated synovial cells. Gene ontology analysis revealed that CTLA-4-Ig internalization did not significantly alter the expression of inflammation-related genes. The therapeutic effect of CTLA-4-Ig appears to extend beyond the lymph nodes into the inflamed synovial compartment through the synergistic inactivation of T cells by the CD80 and PD-L1 axes.

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.

Differential Changes in ACPA Fine Specificity and Gene Expression in a Randomized Trial of Abatacept and Adalimumab in Rheumatoid Arthritis

INTRODUCTION

The biologics abatacept and adalimumab have different mechanisms of action (MoAs). We analyzed data from patients with rheumatoid arthritis treated in AMPLE (NCT00929864) to explore the pharmacodynamic effects of abatacept or adalimumab on anti-citrullinated protein antibodies (ACPAs) and gene expression.

METHODS

AMPLE was a phase IIIb, 2-year, randomized, head-to-head trial of abatacept versus adalimumab. Post hoc analyses of baseline anti-cyclic citrullinated peptide-2 (anti-CCP2, an ACPA surrogate) positive (+) status and ACPA fine-specificity profiles over time, as well as transcriptional profiling (peripheral whole blood), were performed.

RESULTS

Of 646 patients treated (abatacept, n = 318; adalimumab, n = 328), ACPA and gene expression data were available from 508 and 566 patients, respectively. In anti-CCP2+ patients (n = 388), baseline fine specificities for most ACPAs were highly correlated; over 2 years, levels decreased with abatacept but not adalimumab. By year 2, expression of genes associated with T cell co-stimulation and antibody production was lower for abatacept versus adalimumab; expression of genes associated with proinflammatory signaling was lower for adalimumab versus abatacept. Treatment modulated the expression of T- and B-cell gene signatures, with differences in CD8+ T cells, activated T cells, plasma cells, B cells, natural killer cells (all lower with abatacept versus adalimumab), and polymorphonuclear leukocytes (higher with abatacept versus adalimumab).

CONCLUSIONS

In AMPLE, despite similar clinical outcomes, data showed that pharmacodynamic/genetic changes after 2 years of abatacept or adalimumab were consistent with drug MoAs. Further assessment of the relationship between such changes and clinical outcomes, including prediction of response, is warranted.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT00929864.

Monocytes and Macrophages in Spondyloarthritis: Functional Roles and Effects of Current Therapies

Spondyloarthritis (SpA) is a family of chronic inflammatory diseases, being the most prevalent ankylosing spondylitis (AS) and psoriatic arthritis (PsA). These diseases share genetic, clinical and immunological features, such as the implication of human leukocyte antigen (HLA) class I molecule 27 (HLA-B27), the inflammation of peripheral, spine and sacroiliac joints and the presence of extra-articular manifestations (psoriasis, anterior uveitis, enthesitis and inflammatory bowel disease). Monocytes and macrophages are essential cells of the innate immune system and are the first line of defence against external agents. In rheumatic diseases including SpA, the frequency and phenotypic and functional characteristics of both cell types are deregulated and are involved in the pathogenesis of these diseases. In fact, monocytes and macrophages play key roles in the inflammatory processes characteristics of SpA. The aim of this review is analysing the characteristics and functional roles of monocytes and macrophages in these diseases, as well as the impact of different current therapies on these cell types.

Toward Overcoming Treatment Failure in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disorder characterized by inflammation and bone erosion. The exact mechanism of RA is still unknown, but various immune cytokines, signaling pathways and effector cells are involved. Disease-modifying antirheumatic drugs (DMARDs) are commonly used in RA treatment and classified into different categories. Nevertheless, RA treatment is based on a "trial-and-error" approach, and a substantial proportion of patients show failed therapy for each DMARD. Over the past decades, great efforts have been made to overcome treatment failure, including identification of biomarkers, exploration of the reasons for loss of efficacy, development of sequential or combinational DMARDs strategies and approval of new DMARDs. Here, we summarize these efforts, which would provide valuable insights for accurate RA clinical medication. While gratifying, researchers realize that these efforts are still far from enough to recommend specific DMARDs for individual patients. Precision medicine is an emerging medical model that proposes a highly individualized and tailored approach for disease management. In this review, we also discuss the potential of precision medicine for overcoming RA treatment failure, with the introduction of various cutting-edge technologies and big data.

A Case of Recalcitrant Linear Morphea Responding to Subcutaneous Abatacept

INTRODUCTION

Linear morphea is an inflammatory condition that is often treated with systemic glucocorticoids and methotrexate, with mycophenolate mofetil being used as an alternative agent. However, there are few published reports on beneficial effect of abatacept for refractory disease. We present a case of a woman in her 30s who presented with linear morphea on her scalp, with a notable response following the addition of subcutaneous abatacept.

METHODS

Computational analysis was performed comparing the immune cell scores of skin biopsies from 5 morphea skin biopsies from 3 unique patients and 15 healthy control skin biopsies. P < 0.05 was considered statistically significant.

RESULTS

Immune cell scores demonstrated a statistically significant enrichment of activated CD4 memory T cells, M1 macrophages, monocytes, and memory B cells comparing skin biopsies of morphea vs healthy controls (p < 0.05 for all).

DISCUSSION

Abatacept may be considered for recalcitrant cases of morphea. Our computational analysis supports a well-designed study to assess abatacept as first line therapy.

A review on applications of abatacept in systemic rheumatic diseases

Abatacept is a CTLA-4Ig fusion protein that selectively modulates the CD80/CD86:CD28 costimulatory pathway required for full T-cell activation. The FDA has approved it to be used to treat adult rheumatoid arthritis, juvenile idiopathic arthritis, and adult active psoriatic arthritis. Considering the vital pathogenic role of the CTLA-4 pathway in autoimmune diseases, abatacept could efficiently treat other systemic rheumatic diseases. Here we reviewed the published literature to profile the perspectives about the off-label uses of abatacept, especially in those refractory cases with inadequate responses to conventional therapies and biologic agents. Abatacept can be a promising therapeutic option and contribute to reducing hormone dependence and correlated adverse events.

Biologic therapies for the treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that primarily affects the synovial joints. If left untreated, persistent synovial inflammation can lead to cartilage and bone destruction, ultimately causing significant longterm disability and mortality. However, since the late 1990s, the combined use of methotrexate, a synthetic diseasemodifying antirheumatic drug (DMARD), and a biological DMARD has revolutionized the treatment of RA. As of 2021, the Korea Food and Drug Administration has approved seven biological DMARDs for RA treatment: four tumor necrosis factor-alpha inhibitors (infliximab, etanercept, adalimumab, and golimumab) and three non-tumor necrosis factor biological products (abatacept, rituximab, and tocilizumab). Although the use of biological products has allowed significant advances in the treatment of RA, there are certain drawbacks, such as high cost, increased infection risk, and the necessity for parenteral route product administration. Therefore, discontinuation of biological DMARD use without a resulting disease flare is the next treatment goal and a desirable result from the standpoint of risk reduction and cost-effectiveness, especially for patients with clinical remission. It is still unclear which biological product is the best. Clinicians must, therefore, personalize the sequence and strategy of treatment by considering patient characteristics, disease activity, comorbidity, and economic condition

Gene expression regulated by abatacept associated with methotrexate and correlation with disease activity in rheumatoid arthritis

Objectives

Abatacept acts as a competitive inhibitor of the CD28/(CD80/86) costimulation signal required for T cell activation. Mechanisms of action of abatacept have not been fully investigated. The objective of this study was to provide detailed insight into the mode of action of Abatacept based on gene expression data.

Methods

In this ancillary study from the APPRAISE trial, we investigated the global molecular effects of Abatacept in whole blood samples collected prospectively in biologic naive rheumatoid arthritis patients (n = 19) at baseline and 6 months after the initiation of Abatacept therapy concomitant with methotrexate. Whole human genome microarrays (4x44K) were performed on both baseline and 6-month samples from responders and non-responders patients categorized according to EULAR criteria. T-test with Benjamini-Hochberg correction was performed to identify significant gene expression changes. Gene Ontology and Single Experiment Analysis tools allowed us to highlight specific biological mechanisms involved in methotrexate/Abatacept.

Results

In methotrexate/Abatacept responders, 672 genes were significantly (q<0.05) dysregulated at 6 months compared to baseline. Correlation analysis highlighted 19 genes whose dysregulations were significantly associated with disease activity variation (p<0.05) and whose functions were associated with proliferation, apoptosis of cells and mitochondrial metabolism, suggesting a restoration of oxidative signaling. The other 653 gene expression changes were relative to direct or indirect effects of methotrexate/Abatacept treatment and were significantly (p<0.005) involved in pathways relative to mRNA processing, proteasome, angiogenesis, apoptosis and TCR signaling. This study highlights new mechanisms of action of methotrexate/Abatacept and may provide new therapeutic targets to prevent autoimmunity in rheumatoid arthritis.

Precision medicine and management of rheumatoid arthritis

Precision medicine (PM) is a very commonly used term that implies a highly individualized and tailored approach to patient management. There are, however, many layers of precision, as for example taking an appropriate patient history, or performing additional lab or imaging tests are already helping to better tailor treatments to the right patient. All this adds to the narrower definition of PM, which implies using the unique molecular characteristics of a patient for management decisions. Big data has become an essential part of PM, including as much information as possible to improve precision of disease management, although integration of multi-source data continues to be a challenge in practical application. In research big data can identify new (sub-)phenotypes in unsupervised analyses, which ultimately advance precision by allowing new targeted therapeutic approaches. We will discuss the current status of PM in rheumatoid arthritis (RA) in the management areas of diagnosis, prognosis, selection of therapy, and decision to reduce therapy. PM markers for diagnosis of RA are usually markers of RA classification rather than diagnosis, and subtypes of RA are potentially underrecognized. Prognostic precision is well established for RA, including markers of disease activity or structure, as well as autoantibodies and genetics. The choice of the right compound in a patient identified to have a poor prognosis, however, remains widely arbitrary. Finally and most recently, the most reliable markers for a safe withdrawal of therapy continue to be lower levels of disease activity and longer presence of remission.

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.

Abatacept reduces disease activity of rheumatoid arthritis independently of modulating anti-citrullinated peptide antibody production

Abatacept may exert its clinical effect on rheumatoid arthritis (RA) by suppressing anti-cyclic citrullinated peptide (CCP) antibody production. This study was undertaken to test this hypothesis by examining the changes of disease activity of RA and anti-CCP antibody levels over time after starting abatacept. Sixty Japanese RA patients who started abatacept were included in this multicenter, prospective observational study. Simple Disease Activity Index (SDAI) and anti-CCP antibody levels were evaluated at 12, 24, and 52 weeks. The mean SDAI score significantly decreased within 12 weeks after starting abatacept and was maintained thereafter. On the contrary, the mean anti-CCP antibody levels did not change until 52 weeks. At the individual level, there were substantial changes of anti-CCP antibody levels, but these were not correlated with the changes of disease activity at any time points. Thus, abatacept reduces the disease activity of RA independently of modulating anti-CCP antibody production.

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.

Abatacept treatment impairs the cell migration and wound healing of oral ulcers in rats: Role of interleukin (IL)-1β, -6 and -10 and CD8/CD30 cells: Influence of abatacept treatment on oral wound healing: Experimental model on rats

The present study aimed to evaluate the healing process of ulcers in the jugal mucosa of Wistar rats treated with abatacept. The rats were randomly assigned to four groups: saline-treated control (0.3 mL/kg) abatacept-treated groups at dosages of 3.2, 8.0 and 20.0 mg/kg/week. After two weeks of subcutaneous (SC) administration, ulcers were introduced into the left jugal mucosa with an 8-mm diameter punch. SC administration was continued until euthanasia (after 1, 3, 7, 14 and 21 days of ulceration), and ulcers were clinically measured and animals weighed. Histological slides were evaluated (healing scores and polymorphonuclear, mononuclear, vessel, and fibroblast/myofibroblast counts). We also performed collagenesis analysis (Picrosirius Red) and immunohistochemistry (induced nitric oxide synthase (iNOS), interleukin (IL)-1beta (1β), -6, -10, plus the analysis of CD8 and CD30). The experiment was repeated to perform a vascular permeability assay. ANOVA 1-way or 2-way/Bonferroni and Kruskal-Wallis/Dunn tests were used for statistical analysis (GraphPad Prism 5.0®, p < 0.05). Abatacept treatment reduced the ulcer diameter and the numbers of polymorphonuclear and mononuclear cells; reduced the CD8+/CD30+ ratio and vascular permeability; and increased collagenesis and IL-10 expression at the beginning of the protocol. At the highest dose, there was a delay in repair and vascular proliferation; a reduction in the number of fibroblasts/myofibroblasts; and prolongation of iNOS, IL- and IL- expression. We conclude that abatacept accelerates the healing of oral ulcers by reducing the migration of inflammatory cells, but overdose of abatacept leads to delayed repair and prolongation of proinflammatory cytokine expression.

Role of biological agents in treatment of rheumatoid arthritis

Advances in understanding of the pathophysiology of rheumatoid arthritis with concurrent advances in protein engineering led to the development of biological disease-modifying antirheumatic drugs which have dramatically revolutionized the treatment of this condition. This review article focuses on the role of biological agents currently employed in the treatment of rheumatoid arthritis, as well as novel biological agents in development.

Abatacept modulates CD80 and CD86 expression and memory formation in human B-cells

BACKGROUND

Cytotoxic T lymphocyte antigen-4 (CTLA-4) limits T-cell activation and is expressed on T-regulatory cells. Human CTLA-4 deficiency results in severe immune dysregulation. Abatacept (CTLA-4 Ig) is approved for the treatment of rheumatoid arthritis (RA) and its mechanism of action is attributed to effects on T-cells. It is known that CTLA-4 modulates the expression of its ligands CD80 and CD86 on antigen presenting cells (APC) by transendocytosis. As B-cells express CD80/CD86 and function as APC, we hypothesize that B-cells are a direct target of abatacept.

OBJECTIVES

To investigate direct effects of abatacept on human B-lymphocytes in vitro and in RA patients.

METHODS

The effect of abatacept on healthy donor B-cells' phenotype, activation and CD80/CD86 expression was studied in vitro. Nine abatacept-treated RA patients were studied. Seven of these were followed up to 24 months, and two up to 12 months only and treatment response, immunoglobulins, ACPA, RF concentrations, B-cell phenotype and ACPA-specific switched memory B-cell frequency were assessed.

RESULTS

B-cell development was unaffected by abatacept. Abatacept treatment resulted in a dose-dependent decrease of CD80/CD86 expression on B-cells in vitro, which was due to dynamin-dependent internalization. RA patients treated with abatacept showed a progressive decrease in plasmablasts and serum IgG. While ACPA-titers only moderately declined, the frequency of ACPA-specific switched memory B-cells significantly decreased.

CONCLUSIONS

Abatacept directly targets B-cells by reducing CD80/CD86 expression. Impairment of antigen presentation and T-cell activation may result in altered B-cell selection, providing a new therapeutic mechanism and a base for abatacept use in B-cell mediated autoimmunity.

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.

Regulatory T-cell dynamics with abatacept treatment in rheumatoid arthritis

The progressive damage in rheumatoid arthritis (RA) has been linked to an increase in inflammatory Th1/Th17 cells and a decrease in number or function of immunomodulatory regulatory T cells (Tregs). Many therapies that are effective in RA are shown to affect Th1/Th17 cells and/or Tregs. One such therapy, abatacept, utilizes a physiologic immunomodulatory molecule called cytotoxic lymphocyte antigen-4 (CTLA-4) which causes contact-dependent inhibition of inflammatory T-cell activation. Recent advances in CTLA-4 research has uncovered the method by which this occurs physiologically but the actions of the CTLA-4Ig fusion protein are still not fully understood. The reported effects of the drug on Treg population number and suppressor function have been very mixed. In this review, we will discuss the current literature surrounding the effects of abatacept in rheumatoid arthritis and explore potential explanations for the differences in results. Future opportunities in this area include contributions to a unified definition for different immune cell populations, LAG3⁺ Tregs which may pose an avenue for further study or the stratification of patients with regards to their specific disease characteristics, resulting in optimized treatment for disease remission.

Conversion to seronegative status after abatacept treatment in patients with early and poor prognostic rheumatoid arthritis is associated with better radiographic outcomes and sustained remission: post hoc analysis of the AGREE study

Objective

To evaluate the effects of the T-cell costimulation blocker abatacept on anti-citrullinated protein antibodies (ACPA) and rheumatoid factor (RF) in early rheumatoid arthritis (RA), and associations between changes in serological status and clinical response.

Methods

Post hoc analysis of the phase III AGREE study in methotrexate (MTX)-naïve patients with early RA and poor prognostic factors. Patients were randomised to abatacept (~10 mg/kg intravenously according to weight range) or placebo, plus MTX over 12 months followed by open-label abatacept plus MTX for 12 months. Autoantibody titres were determined by ELISA at baseline and months 6 and 12 (double-blind phase). Conversion to seronegative status and its association with clinical response were assessed at months 6 and 12.

Results

Abatacept plus MTX was associated with a greater decrease in ACPA (but not RF) titres and higher rates of both ACPA and RF conversion to seronegative status versus MTX alone. More patients converting to ACPA seronegative status receiving abatacept plus MTX achieved remission according to Disease Activity Score in 28 joints (C-reactive protein) or Clinical Disease Activity Index than patients who remained ACPA seropositive. Patients who converted to ACPA seronegative status treated with abatacept plus MTX had a greater probability of achieving sustained remission and less radiographic progression than MTX alone or patients who remained ACPA seropositive (either treatment).

Conclusions

Treatment with abatacept plus MTX was more likely to induce conversion to ACPA/RF seronegative status in patients with early, erosive RA. Conversion to ACPA seronegative status was associated with better clinical and radiographic outcomes.

Trial registration number

NCT00122382

Rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic, inflammatory, autoimmune disease that primarily affects the joints and is associated with autoantibodies that target various molecules including modified self-epitopes. The identification of novel autoantibodies has improved diagnostic accuracy, and newly developed classification criteria facilitate the recognition and study of the disease early in its course. New clinical assessment tools are able to better characterize disease activity states, which are correlated with progression of damage and disability, and permit improved follow-up. In addition, better understanding of the pathogenesis of RA through recognition of key cells and cytokines has led to the development of targeted disease-modifying antirheumatic drugs. Altogether, the improved understanding of the pathogenetic processes involved, rational use of established drugs and development of new drugs and reliable assessment tools have drastically altered the lives of individuals with RA over the past 2 decades. Current strategies strive for early referral, early diagnosis and early start of effective therapy aimed at remission or, at the least, low disease activity, with rapid adaptation of treatment if this target is not reached. This treat-to-target approach prevents progression of joint damage and optimizes physical functioning, work and social participation. In this Primer, we discuss the epidemiology, pathophysiology, diagnosis and management of RA.

Abatacept: A Review in Rheumatoid Arthritis

The biological DMARD (bDMARD) abatacept (Orencia^®), a recombinant fusion protein, selectively modulates a co-stimulatory signal necessary for T-cell activation. In the EU, abatacept is approved for use in patients with highly active and progressive rheumatoid arthritis (RA) not previously treated with methotrexate. Abatacept is also approved for the treatment of moderate to severe active RA in patients with an inadequate response to previous therapy with at least one conventional DMARD (cDMARD), including methotrexate or a TNF inhibitor. In phase III trials, beneficial effects on RA signs and symptoms, disease activity, structural damage progression and physical function were seen with intravenous (IV) or subcutaneous (SC) abatacept regimens, including abatacept plus methotrexate in methotrexate-naive patients with early RA and poor prognostic factors, and abatacept plus methotrexate or other cDMARDs in patients with inadequate response to methotrexate or TNF inhibitors. Benefits were generally maintained during longer-term follow-up. Absolute drug-free remission rates following withdrawal of all RA treatments were significantly higher with abatacept plus methotrexate than with methotrexate alone. Both IV and SC abatacept were generally well tolerated, with low rates of immunogenicity. Current evidence therefore suggests that abatacept is a useful treatment option for patients with RA.

Targeting the Monocyte-Macrophage Lineage in Solid Organ Transplantation

There is an unmet clinical need for immunotherapeutic strategies that specifically target the active immune cells participating in the process of rejection after solid organ transplantation. The monocyte–macrophage cell lineage is increasingly recognized as a major player in acute and chronic allograft immunopathology. The dominant presence of cells of this lineage in rejecting allograft tissue is associated with worse graft function and survival. Monocytes and macrophages contribute to alloimmunity via diverse pathways: antigen processing and presentation, costimulation, pro-inflammatory cytokine production, and tissue repair. Cross talk with other recipient immune competent cells and donor endothelial cells leads to amplification of inflammation and a cytolytic response in the graft. Surprisingly, little is known about therapeutic manipulation of the function of cells of the monocyte–macrophage lineage in transplantation by immunosuppressive agents. Although not primarily designed to target monocyte–macrophage lineage cells, multiple categories of currently prescribed immunosuppressive drugs, such as mycophenolate mofetil, mammalian target of rapamycin inhibitors, and calcineurin inhibitors, do have limited inhibitory effects. These effects include diminishing the degree of cytokine production, thereby blocking costimulation and inhibiting the migration of monocytes to the site of rejection. Outside the field of transplantation, some clinical studies have shown that the monoclonal antibodies canakinumab, tocilizumab, and infliximab are effective in inhibiting monocyte functions. Indirect effects have also been shown for simvastatin, a lipid lowering drug, and bromodomain and extra-terminal motif inhibitors that reduce the cytokine production by monocytes–macrophages in patients with diabetes mellitus and rheumatoid arthritis. To date, detailed knowledge concerning the origin, the developmental requirements, and functions of diverse specialized monocyte–macrophage subsets justifies research for therapeutic manipulation. Here, we will discuss the effects of currently prescribed immunosuppressive drugs on monocyte/macrophage features and the future challenges.

A randomised phase II study evaluating the efficacy and safety of subcutaneously administered ustekinumab and guselkumab in patients with active rheumatoid arthritis despite treatment with methotrexate

Objective

Interleukin (IL)-12 and IL-23 have been implicated in the pathogenesis of rheumatoid arthritis (RA). The safety and efficacy of ustekinumab, a human monoclonal anti-IL-12/23 p40 antibody, and guselkumab, a human monoclonal anti-IL-23 antibody, were evaluated in adults with active RA despite methotrexate (MTX) therapy.

Methods

Patients were randomly assigned (1:1:1:1:1) to receive placebo at weeks 0, 4 and every 8 weeks (n=55), ustekinumab 90 mg at weeks 0, 4 and every 8 weeks (n=55), ustekinumab 90 mg at weeks 0, 4 and every 12 weeks (n=55), guselkumab 50 mg at weeks 0, 4 and every 8 weeks (n=55), or guselkumab 200 mg at weeks 0, 4 and every 8 weeks (n=54) through week 28; all patients continued a stable dose of MTX (10–25 mg/week). The primary end point was the proportion of patients with at least a 20% improvement in the American College of Rheumatology criteria (ACR 20) at week 28. Safety was monitored through week 48.

Results

At week 28, there were no statistically significant differences in the proportions of patients achieving an ACR 20 response between the combined ustekinumab group (53.6%) or the combined guselkumab group (41.3%) compared with placebo (40.0%) (p=0.101 and p=0.877, respectively). Through week 48, the proportions of patients with at least one adverse event (AE) were comparable among the treatment groups. Infections were the most common type of AE.

Conclusions

Treatment with ustekinumab or guselkumab did not significantly reduce the signs and symptoms of RA. No new safety findings were observed with either treatment.

Trial registration number

NCT01645280.

Rheumatoid arthritis

Rheumatoid arthritis is a chronic inflammatory joint disease, which can cause cartilage and bone damage as well as disability. Early diagnosis is key to optimal therapeutic success, particularly in patients with well-characterised risk factors for poor outcomes such as high disease activity, presence of autoantibodies, and early joint damage. Treatment algorithms involve measuring disease activity with composite indices, applying a treatment-to-target strategy, and use of conventional, biological, and newz non-biological disease-modifying antirheumatic drugs. After the treatment target of stringent remission (or at least low disease activity) is maintained, dose reduction should be attempted. Although the prospects for most patients are now favourable, many still do not respond to current therapies. Accordingly, new therapies are urgently required. In this Seminar, we describe current insights into genetics and aetiology, pathophysiology, epidemiology, assessment, therapeutic agents, and treatment strategies together with unmet needs of patients with rheumatoid arthritis.

Cell Therapy for Prophylactic Tolerance in Immunoglobulin E-mediated Allergy

Background

Therapeutic strategies for the prophylaxis of IgE-mediated allergy remain an unmet medical need. Cell therapy is an emerging approach with high potential for preventing and treating immunological diseases.

We aimed to develop a cell-based therapy inducing permanent allergen-specific immunological tolerance for preventing IgE-mediated allergy.

Methods

Wild-type mice were treated with allergen-expressing bone marrow cells under a short course of tolerogenic immunosuppression (mTOR inhibition and costimulation blockade). Bone marrow was retrieved from a novel transgenic mouse ubiquitously expressing the major grass pollen allergen Phl p 5 as a membrane-anchored protein (BALB/c-Tg[Phlp5-GFP], here mPhl p 5). After transplantation recipients were IgE-sensitized at multiple time points with Phl p 5 and control allergen.

Results

Mice treated with mPhl p 5 bone marrow did not develop Phl p 5-specific IgE (or other isotypes) despite repeated administration of the allergen, while mounting and maintaining a strong humoral response towards the control allergen. Notably, Phl p 5-specific T cell responses and allergic airway inflammation were also completely prevented. Interestingly allergen-specific B cell tolerance was maintained independent of Treg functions indicating deletional tolerance as underlying mechanism.

Conclusion

This proof-of-concept study demonstrates that allergen-specific immunological tolerance preventing occurrence of allergy can be established through a cell-based therapy employing allergen-expressing leukocytes.

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Avoidance of IgE-mediated allergy is established by development of a tolerogenic cell-based protocol.

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Transplantation of syngeneic allergen-bearing bone marrow cells into recipients leads to tolerance towards the introduced allergen.

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Prevention of T-and B-cell responses and allergic asthma is induced by cell transfer with non-toxic pretreatment.

IgE-mediated allergy affects about 30% of the population in industrialized countries. To prevent allergy we developed a cell-based protocol with the concept to modify body's own cells to express an allergen and to reinfuse those modified cells. This concept leads to avoidance of allergic reactions after allergen contact such as specific IgE production and the development of allergic asthma. This is demonstrated in a syngeneic model in mice (i.e. autologous in human) by transplanting bone marrow cells of a unique allergen-expressing transgenic mouse into pretreated recipients.

Co-stimulation Therapy in Rheumatoid Arthritis: Today and Tomorrow

Abatacept is the only T cell co-stimulation modulator approved thus far for the treatment of moderate-to-severe rheumatoid arthritis (RA) and is licensed for use in patients with an inadequate response to methotrexate (MTX) and/or anti-tumor necrosis factor (anti-TNF) therapy. The upstream mechanism of action of abatacept leads to downstream effects in a variety of cell types associated with the production of autoantibodies and pro-inflammatory cytokines implicated in RA. Accumulating data also suggest effects on other cells involved in the pathogenesis of RA, including regulatory T cells and osteoclasts. Clinical trials have demonstrated that abatacept is an effective and well-tolerated treatment in RA. More recently, evidence from the Assessing Very Early Rheumatoid arthritis Treatment (AVERT) trial showed that complete drug-free remission following treatment with abatacept may be a possibility in some patients with early RA, indicating that the disease course could be altered by early intervention. Equivalent efficacy and onset of action of abatacept and anti-TNF therapy have also been demonstrated in patients with an inadequate response to MTX in the Abatacept versus adaliMumab comParison in bioLogic-naïvE rheumatoid arthritis subjects with background methotrexate (AMPLE) trial. Together, these findings support the use of abatacept in early and established RA.

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.

Rheumatoid arthritis therapy reappraisal: strategies, opportunities and challenges

Rheumatoid arthritis (RA) is considered a chronic disease that cannot be cured. Biologic agents have enabled good therapeutic successes; however, the response to biologic therapy depends on treatment history and, especially, disease duration. In general, the more drug-experienced the patients, the lower the response rates, although this limitation can be overcome by promptly adjusting or switching treatment in a treat-to-target approach. Another challenge is the question of how long therapy should be continued once the treatment target, which should be remission or at least a state of low disease activity, has been reached. The data available suggest that, in most patients with established disease, cessation of biologic therapy will be followed by disease flares, whereas a reduction of dose or an increase in the interval between doses enables maintenance of treatment success. Induction therapy very early in the disease course followed by withdrawal of the biologic agent might also be a feasible approach to attain sustained good outcomes, but currently available data are not strong enough to allow for such a conclusion to be reached. Taken together, this underscores the importance of research into the cause(s) of RA so that curative therapies can be developed.

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.

Pneumocystis jirovecii Pneumonia in a Patient with Rheumatoid Arthritis Treated with Abatacept

Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovial membrane inflammation and joint cartilage destruction. Abatacept is a biologic agent that blocks the costimulation signals, preventing antigen presentation and proliferation of T lymphocytes. It is approved for the treatment of patients with RA. Pneumocystis jirovecii pneumonia (PJP) is an infectious disease complicating several immunosuppressive drugs. PJP associated with abatacept has not been reported yet in the medical literature. Various factors, such as the mechanism of action of abatacept, may contribute to predisposing to  Pneumocystis jirovecii infection. In this paper, we report a patient with RA who developed PJP under abatacept treatment.

Blockade of co-stimulation in chronic inflammatory diseases

Costimulatory molecules are key elements in T cell activation. Therapeutic inhibition of costimulatory pathways have been recognized as valid therapeutic strategies in the treatment of various inflammatory diseases. This article will describe their mechanisms of action and will summarize the results from clinical trials in the field of rheumatologic diseases.

Abatacept (cytotoxic T lymphocyte antigen 4-immunoglobulin) improves B cell function and regulatory T cell inhibitory capacity in rheumatoid arthritis patients non-responding to anti-tumour necrosis factor-α agents

The use of biological agents combined with methotrexate (MTX) in rheumatoid arthritis (RA) patients has strongly improved disease outcome. In this study, the effects of abatacept on the size and function of circulating B and T cells in RA patients not responding to anti-tumour necrosis factor (TNF)-α have been analysed, with the aim of identifying immunological parameters helpful to choosing suitable tailored therapies. We analysed the frequency of peripheral B and T cell subsets, B cell function and T regulatory cell (Treg ) inhibitory function in 20 moderate/severe RA patients, according to the European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) criteria, primary non-responders to one TNF-α blocking agent, who received abatacept + MTX. Patients were studied before and 6 months after therapy. We found that abatacept therapy significantly reduced disease activity score on 44 joints (DAS)/erythrocyte sedimentation rate (ESR) values without causing severe side effects. The size of the circulating B and T cell compartments in RA patients was not significantly different from healthy donors, but B cell proliferation and plasma cell differentiation was impaired before therapy and restored by abatacept. While Treg cell frequency was normal, its inhibitory function was absent before therapy and was partially recovered 6 months after abatacept. B and Treg cell function is impaired in RA patients not responding to the first anti-TNF-α agent. Abatacept therapy was able to rescue immune function and led to an effective and safe clinical outcome, suggesting that RA patients, in whom anti-TNF-α failed, are immunologically prone to benefit from an agent targeting a different pathway.

Regulation of B lymphocytes and plasma cells by innate immune mechanisms and stromal cells in rheumatoid arthritis

B cells mediate multiple functions that influence immune and inflammatory responses in rheumatoid arthritis. Production of a diverse array of autoantibodies can happen at different stages of the disease, and are important markers of disease outcome. In turn, the magnitude and quality of acquired humoral immune responses is strongly dependent on signals delivered by innate immune cells. Additionally, the milieu of cells and chemokines that constitute a niche for plasma cells rely strongly on signals provided by stromal cells at different anatomical locations and times. The chronic inflammatory state therefore importantly impacts the developing humoral immune response and its intensity and specificity. We focus this review on B cell biology and the role of the innate immune system in the development of autoimmunity in patients with rheumatoid arthritis.