Morbidity and mortality in rheumatoid arthritis patients with prolonged and profound therapy-induced lymphopenia

Emerging strategies to bypass transplant rejection via biomaterial-assisted immunoengineering: Insights from islets and beyond

Novel transplantation techniques are currently under development to preserve the function of impaired tissues or organs. While current technologies can enhance the survival of recipients, they have remained elusive to date due to graft rejection by undesired in vivo immune responses despite systemic prescription of immunosuppressants. The need for life-long immunomodulation and serious adverse effects of current medicines, the development of novel biomaterial-based immunoengineering strategies has attracted much attention lately. Immunomodulatory 3D platforms can alter immune responses locally and/or prevent transplant rejection through the protection of the graft from the attack of immune system. These new approaches aim to overcome the complexity of the long-term administration of systemic immunosuppressants, including the risks of infection, cancer incidence, and systemic toxicity. In addition, they can decrease the effective dose of the delivered drugs via direct delivery at the transplantation site. In this review, we comprehensively address the immune rejection mechanisms, followed by recent developments in biomaterial-based immunoengineering strategies to prolong transplant survival. We also compare the efficacy and safety of these new platforms with conventional agents. Finally, challenges and barriers for the clinical translation of the biomaterial-based immunoengineering transplants and prospects are discussed.

Treatment of autoimmunity: The impact of disease-modifying therapies in multiple sclerosis and comorbid autoimmune disorders

More than 10 disease-modifying therapies (DMT) are approved by the European Medicines Agency (EMA) and the US Food and Drug Administration (FDA) for the treatment of multiple sclerosis (MS) and new therapeutic options are on the horizon. Due to different underlying therapeutic mechanisms, a more individualized selection of DMTs in MS is possible, taking into account the patient's current situation. Therefore, concomitant treatment of various comorbid conditions, including autoimmune mediated disorders such as rheumatoid arthritis, should be considered in MS patients. Because the pathomechanisms of autoimmunity partially overlap, DMT could also treat concomitant inflammatory diseases and simplify the patient's treatment. In contrast, the exacerbation and even new occurrence of several autoimmune diseases have been reported as a result of immunomodulatory treatment of MS. To simplify treatment and avoid disease exacerbation, knowledge of the beneficial and adverse effects of DMT in other autoimmune disorders is critical. Therefore, we conducted a literature search and described the beneficial and adverse effects of approved and currently studied DMT in a large number of comorbid autoimmune diseases, including rheumatoid arthritis, ankylosing spondylitis, inflammatory bowel diseases, cutaneous disorders including psoriasis, Sjögren´s syndrome, systemic lupus erythematosus, systemic vasculitis, autoimmune hepatitis, and ocular autoimmune disorders. Our review aims to facilitate the selection of an appropriate DMT in patients with MS and comorbid autoimmune diseases.

Non-Conventional Clinical Uses of TSH Receptor Antibodies: The Case of Chronic Autoimmune Thyroiditis

Anti TSH receptor antibodies (TSHrAb) are a family of antibodies with different activity, some of them stimulating thyroid function (TSAb), others with blocking properties (TBAb), it is a common finding that antibodies with different function might coexist in the same patient and can modulate the function of the thyroid. However, most of the labs routinely detect all antibodies binding to the TSH receptor (TRAb, i.e. TSH-receptor antibodies detected by binding assay without definition of functional property). Classical use of TSHr-Ab assay is in Graves' disease where they are tested for diagnostic and prognostic issues; however, they can be used in specific settings of chronic autoimmune thyroiditis (CAT) as well. Aim of the present paper is to highlight these conditions where detection of TSHr-Ab can be of clinical relevance. Prevalence of TSHrAb is different in in the 2 main form of CAT, i.e. classical Hashimoto's thyroiditis and in atrophic thyroiditis, where TBAb play a major role. Simultaneous presence of both TSAb and TBAb in the serum of the same patient might have clinical implication and cause the shift from hyperthyroidism to hypothyroidism and vice versa. Evaluation of TRAb is recommended in case of patients with Thyroid Associated Orbitopathy not associated with hyperthyroidism. At present, however, the most relevant recommendation for the use of TRAb assay is in patients with CAT secondary to a known agent; in particular, after treatment with alemtuzumab for multiple sclerosis. In conclusion, the routine use of anti-TSH receptor antibodies (either TRAb or TSAb/TBAb) assay cannot be suggested at the present for diagnosis/follow up of patients affected by CAT; there are, however, several conditions where their detection can be clinically relevant.

Haematological abnormalities in new-onset rheumatoid arthritis and risk of common infections: a population-based study

OBJECTIVES

To describe the prevalence of haematological abnormalities in individuals with RA at the point of diagnosis in primary care and the associations between haematological abnormalities, vaccinations and subsequent risk of common infections.

METHODS

We studied 6591 individuals with newly diagnosed RA between 2004 and 2016 inclusive using the UK Royal College of General Practitioners Research and Surveillance Centre primary care database. The prevalence of haematological abnormalities at diagnosis (anaemia, neutropenia and lymphopenia) was established. Cox proportional hazards models were used to evaluate the association between each haematological abnormality and time to common infections and the influence of vaccination status (influenza and pneumococcal vaccine) on time to common infections in individuals with RA compared with a matched cohort of individuals without RA.

RESULTS

Anaemia was common at RA diagnosis (16.1% of individuals), with neutropenia (0.6%) and lymphopenia (1.4%) less so. Lymphopenia and anaemia were associated with increased infection risk [hazard ratio (HR) 1.18 (95% CI 1.08, 1.29) and HR 1.37 (95% CI 1.08, 1.73), respectively]. There was no evidence of an association between neutropenia and infection risk [HR 0.94 (95% CI 0.60, 1.47)]. Pneumonia was much more common in individuals with early RA compared with controls. Influenza vaccination was associated with reduced risk of influenza-like illness only for individuals with RA [HR 0.58 (95% CI 0.37, 0.90)].

CONCLUSION

At diagnosis, anaemia and lymphopenia, but not neutropenia, increase the risk of common infections in individuals with RA. Our data support the effectiveness of the influenza vaccination in individuals with RA.

2019 European Thyroid Association Guidelines on the Management of Thyroid Dysfunction following Immune Reconstitution Therapy

Thyroid dysfunction (TD) frequently occurs as an autoimmune complication of immune reconstitution therapy (IRT), especially in individuals with multiple sclerosis treated with alemtuzumab, a pan-lymphocyte depleting drug with subsequent recovery of immune cell numbers. Less frequently, TD is triggered by highly active antiretroviral therapy (HAART) in patients infected with human immunodeficiency virus (HIV), or patients undergoing bone-marrow/hematopoietic-stem-cell transplantation (BMT/HSCT). In both alemtuzumab-induced TD and HIV/HAART patients, the commonest disorder is Graves' disease (GD), followed by hypothyroidism and thyroiditis; Graves' orbitopathy is observed in some GD patients. On the contrary, GD is rare post-BMT/HSCT, where hypothyroidism predominates probably as a consequence of the associated radiation damage. In alemtuzumab-induced TD, the autoantibodies against the thyrotropin receptor (TRAb) play a major role, and 2 main aspects distinguish this condition from the spontaneous form: (1) up to 20% of GD cases exhibit a fluctuating course, with alternating phases of hyper- and hypothyroidism, due to the coexistence of TRAb with stimulating and blocking function; (2) TRAb are also positive in about 70% of hypothyroid patients, with blocking TRAb responsible for nearly half of the cases. The present guidelines will provide up-to-date recommendations and suggestions dedicated to all phases of IRT-induced TD: (1) screening before IRT (recommendations 1-3); (2) monitoring during/after IRT (recommendations 4-7); (3) management of TD post-IRT (recommendations 8-17). The clinical management of IRT-induced TD, and in particular GD, can be challenging. In these guidelines, we propose a summary algorithm which has particular utility for nonspecialist physicians and which is tailored toward management of alemtuzumab-induced TD. However, we recommend prompt referral to specialist endocrinology services following diagnosis of any IRT-induced TD diagnosis, and in particular for pregnant women and those considering pregnancy.

Abatacept for the treatment of rheumatoid arthritis

INTRODUCTION

Rheumatoid arthritis (RA) is a complex disease in which different mechanisms are involved. Studies suggest a key role for aberrant pathways of T-cell activation in the initiation and perpetuation of disease. Abatacept is a fusion protein composed of the Fc region of the immunoglobulin G1 (IgG1) fused to the extracellular domain of cytotoxic T lymphocyte-associated antigen (CTLA4). It has the ability to modulate T-cell activation by interfering with co-stimulation of these cells, a necessary step to become activated. This suggests that abatacept may play a role in the progression and/or even the initiation of RA. Areas covered: a review of the different studies carried out during clinical development of abatacept was performed. Both formulations, intravenous (IV) and subcutaneous (SC), showed a similar and consistent efficacy and safety profile. Abatacept was effective both in RA patients not responding to methotrexate (MTX) and to tumor necrosis factor (TNF) inhibitors. Expert commentary: abatacept, with its unique mechanism of action, proved to be a useful therapeutic alternative in RA, also having an acceptable safety profile. Evidence points out that abatacept may be able to alter the RA disease course. Ongoing studies will clarify this issue.

Immune reconstitution 20 years after treatment with alemtuzumab in a rheumatoid arthritis cohort: implications for lymphocyte depleting therapies

Background

Alemtuzumab, an anti-CD52 monoclonal antibody, was administered to patients with RA between 1991 and 1994. We have followed a cohort of recipients since that time and previously reported significant delays in immune reconstitution. Here we report >20 years of follow-up data from this unique cohort.

Method

Surviving alemtuzumab recipients were age, sex and disease duration matched with RA controls. Updated mortality and morbidity data were collected for alemtuzumab recipients. For both groups antigenic responses were assessed following influenza, Pneumovax II and combined diphtheria/tetanus/poliovirus vaccines. Circulating cytokines and lymphocyte subsets were also quantified.

Results

Of 16 surviving alemtuzumab recipients, 13 were recruited: 9 recipients underwent a full clinical assessment and 4 had case notes review only. Since our last review 10 patients had died from causes of death consistent with long-standing RA, and no suggestion of compromised immune function. Compared with controls the alemtuzumab cohort had significantly reduced CD4⁺ and CD8⁺ central memory T-cells, CD5⁺ B cells, naïve B cells and CD19⁺CD24^hiCD38^hi transitional (putative regulatory) B cells. Nonetheless vaccine responses were comparable between groups. There were significantly higher serum IL-15 and IFN-γ levels in the alemtuzumab cohort. IL-15 levels were inversely associated with CD4⁺ total memory and central memory T cells.

Conclusion

After 20 years the immune system of alemtuzumab recipients continues to show differences from disease controls. Nonetheless mortality and morbidity data, alongside vaccination responses, do not suggest clinical immune compromise. As lymphodepleting therapies, including alemtuzumab, continue to be administered this work is important with regard to long-term immune monitoring and stages of immune recovery.

Lymphopenia in early arthritis: Impact on diagnosis and 3-year outcomes (ESPOIR cohort)

OBJECTIVES

In patients with early arthritis naive to disease-modifying antirheumatic drugs, we evaluated the prevalence of initial and persistent lymphopenia, underlying diagnoses, and risk of infection or malignancy.

METHODS

Eight hundred and thirteen patients with early arthritis included in the ESPOIR cohort had a clinical examination, laboratory tests (viral serology, immunological tests, and cytokine profile), and radiographs. We determined the prevalence of lymphopenia at baseline and after 3 years, associated factors, diagnoses, and risk of infection or malignancy.

RESULTS

At baseline, 50/813 (6.2%) patients had lymphopenia. Lymphopenia was associated with positive rheumatoid factor (P=0.02), cytopenia (P≤0.05), hepatitis C (P=0.05), higher C-reactive protein and DAS28 (P≤0.05 for both). Cytokine profile and radiological progression were not significantly different between patients with and without lymphopenia. Suspected diagnoses at inclusion were rheumatoid arthritis (RA, n=27), unclassified arthritis (n=15), systemic lupus erythematosus (SLE, n=3), spondyloarthritis (n=2), Sjögren's syndrome (n=1), hematologic disease (n=1), and fibromyalgia (n=1). Fifteen patients out of 42 (35.7%) with initial lymphopenia had persistent lymphopenia after 3 years, including 5 with documented causes (lupus, hepatitis C, undernutrition, azathioprine, and tamoxifen); none had PVB19, HIV, or HBV infection and none experienced infections, solid or hematologic malignancies during follow-up. Final diagnoses in these 15 patients were RA (n=6), unclassified arthritis (n=6), SLE (n=1), spondyloarthritis (n=1), and fibromyalgia (n=1).

CONCLUSIONS

Lymphopenia is rare in early arthritis. The most common rheumatic cause is RA, in which marked inflammation and other cytopenias are common. Lymphopenia in early arthritis is often short-lived, even when methotrexate is prescribed.

Lymphocytes as an Indicator for Initial Kidney Function: A Single Center Analysis of Outcome after Alemtuzumab or Basiliximab Induction

Alemtuzumab, an anti-CD52 T-cell and B-cell depleting monoclonal antibody, is established for induction therapy in renal transplantation (KTx). We herein provide a comparative analysis between alemtuzumab and basiliximab induction therapy and correlate lymphocyte depletion and recovery with the clinical course after KTx. This is a single center retrospective analysis of 225 patients/consecutive kidney transplantations treated with alemtuzumab for lymphocyte depletion and 205 recipients treated with basiliximab. Mean lymphocyte counts were 22.8 ± 9.41% before Tx and 2.61 ± 3.11% between week 1 and week 3 in the alemtuzumab group and 23.77 ± 10.42% before Tx and 13.92 ± 8.20% in the basiliximab group. Delayed graft function (DGF), cytomegalovirus (CMV) status, and recipient age showed a significant correlation with lymphocyte counts in the alemtuzumab group only. The outcome was read in reference to the velocity of lymphocyte recovery and in comparison to the control group. Lymphocyte counts early after transplantation, following alemtuzumab treatment, could be identified as a predictive factor for kidney function early after transplantation. A detailed analysis of phenotype and function of lymphocytes after alemtuzumab induction together with a correlation with the clinical course is warranted.

Brief report: deficient thymic output in rheumatoid arthritis despite abundance of prethymic progenitors

Objective

To determine the frequencies of common lymphoid progenitors (CLPs) and recent thymic emigrants (RTEs) in patients with rheumatoid arthritis (RA) and healthy control subjects.

Methods

Flow cytometry was performed to determine the frequencies of CLPs and RTEs in the peripheral blood of 101 control subjects and 51 patients with RA. Thirteen of these patients were also analyzed longitudinally for 6 months after initiation of treatment with a tumor necrosis factor (TNF) inhibitor.

Results

A significant correlation between the frequencies of CLPs and RTEs was observed in healthy control subjects. The frequencies of both CLPs and RTEs decreased with age and correlated inversely with absolute lymphocyte numbers in peripheral blood. In patients with RA, the frequencies of RTEs were significantly decreased compared with the frequencies in control subjects. Importantly, the frequencies of CLPs were significantly higher in patients with RA compared with control subjects. Therapeutic TNF blockade further increased the frequency of CLPs, thereby normalizing thymic output, as indicated by an increase in the number of RTEs.

Conclusion

Thymic insufficiency in RA is not attributable to an inadequate supply of progenitor cells to the thymus. Thus, insufficient numbers of RTEs could result from inadequate thymic T cell neogenesis, or alternatively, could be a consequence of high CD4+ T cell turnover, homeostatic proliferation, and subsequent dilution of the RTE population.

A review of Campath in autoimmune disease: Biologic therapy in the gray zone between immunosuppression and immunoablation

Campath, the subject of this review, is an example of a broadly targeted biologic agent, approved for patients with B-CLL, which may combine immunosuppressive as well as immunoablative properties. For many years Campath has been in clinical use as an immunosuppressive agent for various autoimmune diseases and as part of the preparative regimes for allogeneic HSCT, successfully preventing graft-versus-host-disease (GVHD). This review summarizes the experience of 24 studies including a total of 323 patients treated with Campath for various autoimmune diseases such as arthritis, MS, vasculitis, autoimmune cytopenias and others. The results demonstrate that Campath is fairly safe and 75% of the patients experienced clinical improvement and 15% of the patients were reported in clinical remission even though improvements were often transient.While other biologic drugs may have to narrow targets, Campath, is able to bridge the gap between immunosuppression and immunoablation and may offer an alternative to human stem cell transplantation avoiding the risks of chemotherapy and radiation.

WITHDRAWN: Abatacept as a first-line biological therapy

The Publisher regrets that this article is an accidental duplication of an article that has already been published, http://dx.doi.org/10.1016/j.autrev.2013.06.008. The duplicate article has therefore been withdrawn.

Modulating the co-stimulatory signal for T cell activation in rheumatoid arthritis: could it be the first step of the treatment?

Advances in our understanding of the key mediators of chronic inflammation and tissue damage in rheumatoid arthritis (RA) have fostered the development of targeted therapies and greatly expanded the available treatment options. Abatacept, a soluble human fusion protein that selectively modulates the co-stimulatory signal required for full T-cell activation, is approved for the treatment of moderate to severe RA in the United States, Canada, and the European Union. This review summarises the data on efficacy (disease activity, quality of life, prevention of structural damage) and safety from randomised clinical trials of abatacept plus methotrexate in patients with: i) active RA and an inadequate response to methotrexate who are naïve to biological disease-modifying anti-rheumatic drugs; and ii) methotrexate-naïve early RA with poor prognostic factors. Novel imaging outcomes and biological changes induced by abatacept treatment are also briefly reviewed. Optimal use of abatacept as a first-line biological therapy is discussed in light of the current recommendations and guidelines.

[Personalized medicine for rheumatoid arthritis : serological and clinical patient profiles to optimize B and T cell targeted therapy]

Nowadays B and T-cell directed biologics in addition to TNF inhibitors are established as effective and safe treatment options for rheumatoid arthritis. As shown by the approval of rituximab for the treatment of systemic vasculitis, these drugs can also be useful for the treatment of other systemic autoimmune diseases; however, to optimize therapeutic strategies, predictive factors for treatment response as well as a good characterized safety profile are essential. So far implementation of real personalized medicine is not feasible in the field of rheumatology, but first biomarkers have already been identified and provide promising results. In this context, it has been shown that a B-cell directed therapy with rituximab is more effective in seropositive patients with rheumatoid arthritis. In addition, characterization of the cytokine milieu as well as of circulating and tissue infiltrating B and T-cell subsets might be useful for prediction of treatment response in the near future.

Development and validation of a risk score for serious infection in patients with rheumatoid arthritis

OBJECTIVE

Infection risk is increased in patients with rheumatoid arthritis (RA), and accurate assessment of the risk of infection could inform clinical decision-making. This study was undertaken to develop and validate a score to predict the 1-year risk of serious infection in patients with RA.

METHODS

We studied a population-based cohort of Olmsted County, Minnesota residents with incident RA ascertained in 1955-1994 whose members were followed up longitudinally, via complete medical records, until January 2000. The validation cohort included residents with incident RA ascertained in 1995-2007. The outcome measure included all serious infections (requiring hospitalization or intravenous antibiotics). Potential predictors were examined using multivariable Cox models. The risk score was estimated directly from the multivariable model, and performance was assessed in the validation cohort using Harrell's C statistic.

RESULTS

Among the 584 RA patients in the original cohort (72% female; mean age 57.5 years), who were followed up for a median of 9.9 years, 252 had ≥ 1 serious infection (646 total infections). Components of the risk score included age, previous serious infection, corticosteroid use, elevated erythrocyte sedimentation rate, extraarticular manifestations of RA, and comorbidities (coronary heart disease, heart failure, peripheral vascular disease, chronic lung disease, diabetes mellitus, alcoholism). Validation analysis revealed good discrimination (C statistic 0.80).

CONCLUSION

RA disease characteristics and comorbidities can be used to accurately assess the risk of serious infection in patients with RA. Knowledge of risk of serious infection in RA patients can influence clinical decision making and inform strategies to reduce and prevent the occurrence of these infections.

Rationale of anti-CD19 immunotherapy: an option to target autoreactive plasma cells in autoimmunity

Anti-CD20 therapy using rituximab directly targeting B cells has been approved for treatment of non-Hodgkin lymphoma, rheumatoid arthritis and anti-neutrophil cytoplasmic antibody-associated vasculitides and has led to reappreciation of B-lineage cells for anti-rheumatic treatment strategies. Moreover, blocking B-cell activating factor with belimumab, a drug that is licensed for treatment of active, seropositive systemic lupus erythematosus (SLE), represents an alternative, indirect anti-B-cell approach interfering with proper B-cell development. While these approaches apparently have no substantial impact on antibody-secreting plasma cells, challenges to improve the treatment of difficult-to-treat patients with SLE remain. In this context, anti-CD19 antibodies have the promise to directly target autoantibody-secreting plasmablasts and plasma cells as well as early B-cell differentiation stages not covered by anti-CD20 therapy. Currently known distinct expression profiles of CD19 by human plasma cell subsets, experiences with anti-CD19 therapies in malignant conditions as well as the rationale of targeting autoreactive plasma cells in patients with SLE are discussed in this review.

Autoimmune polyglandular syndrome type II after bone marrow transplant: real transfer or acceleration of a programmed disease?

We report a case of autoimmune polyglandular syndrome type II that developed in an 11-year-old boy with homozygous sickle cell disease after allogeneic bone marrow transplant; the donor was his father, who was human leukocyte antigen identical and had vitiligo. On day 24 after transplant, the patient developed grade 1 acute graft-versus-host disease, which was controlled over a period of 3 months with corticosteroid-induced immunosuppression. Full donor engraftment was documented on day 31 after transplant, and this was further confirmed on days 59, 231, 321, 472, 549, and 720. Three months after transplant, the recipient developed adrenal insufficiency, and at 13 months, he developed vitiligo. Seventeen months after transplant, autoimmune thyroid disease, positive for thyroid peroxidase and thyroglobulin autoantibodies, was diagnosed. At the same time, we identified adrenal insufficiency in the donor. We analyzed a serum sample from the recipient for autoantibody markers for type 1 autoimmune diabetes mellitus. The sample was positive for antiglutamic acid decarboxylase. Antibody against 21-hydroxylase enzyme was also found (261 U/mL; normal value, < 1 U/mL). We conclude that the recipient developed autoimmune polyglandular syndrome type II after bone marrow transplant from his father, who was probably affected by the same syndrome.

The role of B cells in solid organ transplantation

The role of antibodies in chronic injury to organ transplants has been suggested for many years, but recently emphasized by new data. We have observed that when immunosuppressive potency decreases either by intentional weaning of maintenance agents or due to homeostatic repopulation after immune cell depletion, the threshold of B cell activation may be lowered. In human transplant recipients the result may be donor-specific antibody, C4d+ injury, and chronic rejection. This scenario has precise parallels in a rhesus monkey renal allograft model in which T cells are depleted with CD3 immunotoxin, or in a CD52-T cell transgenic mouse model using alemtuzumab to deplete T cells. Such animal models may be useful for the testing of therapeutic strategies to prevent DSA. We agree with others who suggest that weaning of immunosuppression may place transplant recipients at risk of chronic antibody-mediated rejection, and that strategies to prevent this scenario are needed if we are to improve long-term graft and patient outcomes in transplantation. We believe that animal models will play a crucial role in defining the pathophysiology of antibody-mediated rejection and in developing effective therapies to prevent graft injury. Two such animal models are described herein.

Activity of alemtuzumab monotherapy in treatment-naive, relapsed, and refractory severe acquired aplastic anemia

Antithymocyte globulin (ATG) + cyclosporine is effective in restoring hematopoiesis in severe aplastic anemia (SAA). We hypothesized that the humanized anti-CD52 mAb alemtuzumab might be active in SAA because of its lymphocytotoxic properties. We investigated alemtuzumab monotherapy from 2003-2010 in treatment-naive, relapsed, and refractory SAA in 3 separate research protocols at the National Institutes of Health. Primary outcome was hematologic response at 6 months. For refractory disease, patients were randomized between rabbit ATG + cyclosporine (n = 27) and alemtuzumab (n = 27); the response rate for alemtuzumab was 37% (95% confidence interval [CI], 18%-57%) and for rabbit ATG 33% (95% CI, 14%-52%; P = .78). The 3-year survival was 83% (95% CI, 68%-99%) for alemtuzumab and 60% (95% CI, 43%-85%) for rabbit ATG (P = .16). For relapsed disease (n = 25), alemtuzumab was administered in a single-arm study; the response rate was 56% (95% CI, 35%-77%) and the 3-year survival was 86% (95% CI, 72%-100%). In treatment-naive patients (n = 16), alemtuzumab was compared with horse and rabbit ATG in a 3-arm randomized study; the response rate was 19% (95% CI 0%-40%), and the alemtuzumab arm was discontinued early. We conclude that alemtuzumab is effective in SAA, but best results are obtained in the relapsed and refractory settings. The present trials were registered at www.clinicaltrials.gov as NCT00195624, NCT00260689, and NCT00065260.

Novel immunotherapeutic approaches for allergy and asthma

The immune response is a tightly regulated process, which normally results in protection from infection and tolerance of innocuous environmental antigens. However, in allergic disease, the activated immune response results in a chronic pro-inflammatory state characterized by antibody secretion (IgE) and T cell activation to normally well-tolerated antigens. Currently, the treatment of allergic disease is focused on the suppression of key inflammatory mediators or inflammatory cell populations and include anti-histamines, anti-leukotrienes, &#x03B2;2 adrenergic receptor agonists and corticosteroids. However, these approaches only provide a temporary suppression of disease symptoms. Successful long-term treatment can only be provided by allergen-specific immunotherapy (allergen-SIT), which restores normal immunity against allergens. This review will discuss novel approaches to the management of allergy and asthma by targeting the T regulatory cell via modulation of the commensal microbiota and allergen-SIT.

Update in the mechanisms of allergen-specific immunotheraphy

Allergic diseases represent a complex innate and adoptive immune response to natural environmental allergens with Th2-type T cells and allergen-specific IgE predominance. Allergen-specific immunotherapy is the most effective therapeutic approach for disregulated immune response towards allergens by enhancing immune tolerance mechanisms. The main aim of immunotherapy is the generation of allergen nonresponsive or tolerant T cells in sensitized patients and downregulation of predominant T cell- and IgE-mediated immune responses. During allergen-specific immunotherapy, T regulatory cells are generated, which secrete IL-10 and induce allergen-specific B cells for the production of IgG4 antibodies. These mechanisms induce tolerance to antigens that reduces allergic symptoms. Although current knowledge highlights the role of T regulatory cell-mediated immunetolerance, definite mechanisms that lead to a successful clinical outcomes of allergen-specific immunotherapy still remains an open area of research.

Treating to re-establish tolerance in inflammatory arthritis - lessons from other diseases

Therapeutic tolerance embraces the concept of 'switching off' immunopathology by specifically targeting elements of the immune system. It has been achievable in preclinical models of transplantation and auto-immunity for more than two decades; however, previous attempts to translate to the clinic have been unsuccessful. Nonetheless, an improved understanding of tolerance mechanisms, along with novel therapeutic agents and strategies, are starting to bear fruit in a number of disease areas. True tolerance is achievable in transplantation settings, and long-term remissions can be induced in various auto-immune and atopic conditions. Equivalent outcomes should be achievable in inflammatory arthritis, although this may require an improved understanding of the immune dysregulation that is intrinsic to rheumatoid arthritis (RA), and better definitions of RA autoantigens. Biomarkers of tolerance induction would rapidly advance the field in all therapeutic areas. This article summarises the advances made in other therapeutic areas, and the lessons learned that we can now apply to RA.

IL-7 and lymphopenia

Interleukin-7 (IL-7) is a growth and anti-apoptotic factor for T-lymphocytes, with potential for clinical use in the treatment of immunodeficiencies due to loss of T-cells. Lymphopenia induced by disease (HIV infection, hemodialysis or Idiopathic CD4+ lymphopenia) or by treatment (high dose chemotherapy or depleting antibodies) for cancer or auto-immune diseases results in increased circulating levels of IL-7 which decline with T-cell recovery, however, the mechanism of such response remains to be elucidated. Furthermore, IL-7 is a major player in the regulation of peripheral T-cell homeostasis and as such is an important candidate cytokine for therapy aimed at improving T-cell reconstitution following lymphopenia. Anti- IL-7 is on the other hand proposed to treat conditions where IL-7 may play a more direct role in pathogenesis such as autoimmune disease like Rheumatoid Arthritis, Multiple Sclerosis or Inflammatory Bowel disease.

A novel strategy to reduce the immunogenicity of biological therapies

Biological therapies, even humanized mAbs, may induce antiglobulin responses that impair efficacy. We tested a novel strategy to induce tolerance to a therapeutic mAb. Twenty patients with relapsing-remitting multiple sclerosis received an initial cycle of alemtuzumab (Campath-1H), up to 120 mg over 5 d, preceded by 500 mg SM3. This Ab differs from alemtuzumab by a single point mutation and is designed not to bind to cells. Twelve months later, they received a second cycle of alemtuzumab, up to 72 mg over 3 d. One month after that, 4 of 19 (21%) patients had detectable serum anti-alemtuzumab Abs compared with 145 of 197 (74%) patients who received two cycles of alemtuzumab without SM3 in the phase 2 CAMMS223 trial (p < 0.001). The efficacy and safety profile of alemtuzumab was unaffected by SM3 pretreatment. Long-lasting "high-zone" tolerance to a biological therapy may be induced by pretreatment with a high i.v. dose of a drug variant, altered to reduce target-binding.

Investigation of the mechanism of action of alemtuzumab in a human CD52 transgenic mouse model

Alemtuzumab is a humanized monoclonal antibody against CD52, an antigen found on the surface of normal and malignant lymphocytes. It is approved for the treatment of B-cell chronic lymphocytic leukaemia and is undergoing Phase III clinical trials for the treatment of multiple sclerosis. The exact mechanism by which alemtuzumab mediates its biological effects in vivo is not clearly defined and mechanism of action studies have been hampered by the lack of cross-reactivity between human and mouse CD52. To address this issue, a transgenic mouse expressing human CD52 (hCD52) was created. Transgenic mice did not display any phenotypic abnormalities and were able to mount normal immune responses. The tissue distribution of hCD52 and the level of expression by various immune cell populations were comparable to those seen in humans. Treatment with alemtuzumab replicated the transient increase in serum cytokines and depletion of peripheral blood lymphocytes observed in humans. Lymphocyte depletion was not as profound in lymphoid organs, providing a possible explanation for the relatively low incidence of infection in alemtuzumab-treated patients. Interestingly, both lymphocyte depletion and cytokine induction by alemtuzumab were largely independent of complement and appeared to be mediated by neutrophils and natural killer cells because removal of these populations with antibodies to Gr-1 or asialo-GM-1, respectively, strongly inhibited the activity of alemtuzumab whereas removal of complement by treatment with cobra venom factor had no impact. The hCD52 transgenic mouse appears to be a useful model and has provided evidence for the previously uncharacterized involvement of neutrophils in the activity of alemtuzumab.

Therapeutic manipulation of immune tolerance in allergic disease

Immune tolerance - the adaptation of the immune system to external antigens or allergens - might be therapeutically manipulated to restore normal immunity in conditions such as allergy, asthma and autoimmune diseases. The field of allergen-specific immunotherapy is experiencing exciting and novel developments for the treatment of allergic and autoimmune diseases, and recent insights into the reciprocal regulation and counter-balance between different T-cell subsets is foreseen to facilitate new strategies for immunointervention. This Review highlights current knowledge of immunomodulatory therapies for the manipulation of immune tolerance and highlights recent approaches to improve allergen-specific immunotherapy for the treatment of allergic diseases.

Alemtuzumab (CAMPATH-1H) for the treatment of acute rejection in kidney transplant recipients: long-term follow-up

BACKGROUND

Alemtuzumab (MabCampath, Campath-1H) is a lymphocyte-depleting monoclonal antibody increasingly used in renal transplantation. This article reports the long-term follow-up data from the first series of patients treated with alemtuzumab for biopsy-proven acute rejection (BPAR).

METHODS

Fifteen patients were identified who had received alemtuzumab for BPAR between November 1991 and June 1994. Patient and allograft survival were compared with a control group consisting of 25 patients with BPAR from the same era treated with intravenous methyl prednisolone, and with a contemporaneous UK renal transplant cohort.

RESULTS

All rejection episodes responded to treatment with alemtuzumab but there was an excess of early infection-associated death in this group. Long-term transplant survival was similar in both groups as was allograft function (mean creatinine concentration at 10 years was 143 micromol/L in alemtuzumab cohort and 183 micromol/L in control cohort, P=0.06). There was no excess incidence of malignancy or cytomegalovirus infection in this prolonged follow-up period.

Therapeutic T-cell manipulation in rheumatoid arthritis: past, present and future

Accumulating evidence suggests that RA is a T-cell-mediated autoimmune disease. Early attempts at disease modulation using strategies such as CD4 mAbs were severely hampered by a lack of biomarkers of autoreactivity. Recently, however, co-stimulation blockade has emerged as an effective treatment for RA. Alongside a greatly improved mechanistic understanding of immune regulation, this has rekindled hopes for authentic and robust immune programming. The final pieces of the jigsaw are not yet in place for RA but, in other disciplines, emerging treatment paradigms such as non-mitogenic anti-CD3 mAbs, autoantigenic peptides and even cellular therapies are providing hope for a future in which immunopathology can be specifically and vigorously curtailed.

Morbidity and mortality in rheumatoid arthritis patients with prolonged therapy-induced lymphopenia: twelve-year outcomes

OBJECTIVE

To assess immunologically relevant outcomes in a cohort of rheumatoid arthritis (RA) patients with prolonged therapy-induced lymphopenia.

METHODS

Morbidity (infection or malignancy) and mortality were assessed in 53 RA patients who were treated with the lymphocytotoxic monoclonal antibody alemtuzumab between 1991 and 1994. Data were obtained by interview, medical record review, and Office for National Statistics mortality monitoring. Lymphocyte subsets were enumerated by flow cytometry. A retrospective, matched-cohort study of mortality was performed with 102 control subjects selected from the European League Against Rheumatism database of patients with rheumatic disorders.

RESULTS

Lymphopenia persisted in the patients: median CD3+CD4+, CD3+CD8+, CD19+, and CD56+ lymphocyte counts measured at a median followup of 11.8 years from the first administration of alemtuzumab were 0.50 x 10(9)/liter, 0.26 x 10(9)/liter, 0.11 x 10(9)/liter, and 0.09 x 10(9)/liter, respectively. Twenty-seven of 51 cases and 46 of 101 controls with available data had died, yielding a mortality rate ratio of 1.20 (95% confidence interval 0.72-1.98). Causes of death were similar to those that would be expected in a hospital-based RA cohort. No opportunistic infections were noted, and only 3 infections were documented following 36 elective orthopedic procedures.

CONCLUSION

Despite continued lymphopenia 11.8 years after therapy, our patient cohort did not exhibit excess mortality or unusual infection-related morbidity, and surgery was well tolerated. These data should be reassuring for clinicians and patients who are considering lymphocytotoxic or other immunomodulatory therapy for RA.

Subcutaneous administration of alemtuzumab in simultaneous pancreas-kidney transplantation

Alemtuzumab (MabCampath, Campath-1H) is a potent lymphocyte-depleting monoclonal antibody increasingly used at induction in solid organ transplantation. Previously, it had been given by intravenous infusion; such administration is associated with a first-dose cytokine release syndrome characterized by fever and hypotension. Subcutaneous administration of alemtuzumab avoids this first-dose reaction while achieving a similar concentration to intravenous administration. The avoidance of infusion-associated hypotension is particularly important in pancreas transplantation where venous thrombosis is a major problem. We therefore treated 21 recipients of combined pancreas and kidney transplants with two 30-mg doses of alemtuzumab administered subcutaneously on days 0 and 1. No patient suffered a first-dose reaction. Lymphocyte depletion after subcutaneous alemtuzumab was profound and comparable to that seen in a group of renal transplant recipients who had received intravenous alemtuzumab. Subcutaneous alemtuzumab was associated with similar rates of acute rejection (14% at 1 year), patient survival (100%), and pancreas and kidney graft survival (95% and 100%, respectively) to those observed in centers using intravenous alemtuzumab in simultaneous pancreas kidney transplantation. There was no excess incidence of adverse events. We therefore recommend this route of administration to all transplant centers using alemtuzumab.

T cell immunomodulation--the Holy Grail of therapeutic tolerance

The concept and practice of therapeutic tolerance has successfully been applied to animal models of autoimmunity and transplantation for more than 2 decades. Finally, there are encouraging signs of its translation to clinical practice. Short courses of anti-CD3 monoclonal antibody therapy have provided lasting benefits in recent-onset type 1 diabetes in association with evidence for the induction of immunoregulatory mechanisms. Co-stimulation blockade with abatacept (CTLA4-Ig) will soon be licensed for the treatment of rheumatoid arthritis - over the past year phase III studies have demonstrated impressive improvement in subjective and objective signs of the disease. T cell depletion is in development for several conditions, again with recent studies demonstrating evidence of immune regulation in some instances. More specific antigen-directed peptide therapies have also been applied to atopic asthma, type 1 diabetes, and adult and juvenile arthritis. The tragic sequelae of the phase I trial of TGN1412 at Northwick Park demonstrated the delicate, but unpredictable, therapeutic ratio of some T-cell-directed treatments and, in the UK, have led to new guidelines for early-phase clinical trials of immune-directed therapies.

Guidelines for assessing immunocompetency in clinical trials for autoimmune diseases

Clinical trials testing the safety and efficacy of immunosuppressive agents for the treatment of autoimmune diseases should also be designed to evaluate immunocompetency. The most clinically relevant outcome for assessing immunocompetency is the infection rate. Therefore, a systematic approach to screening, monitoring, and reporting infections, modeled after the recommendations of the American Society of Transplantation, is presented. However, because the baseline infection rate in most autoimmune diseases is low, additional tests for immunocompetency should be considered. Evaluation of vaccine responses, an alternative clinically relevant approach, may be particularly useful. Other adjunctive approaches to evaluation of immunocompetency are discussed including immunization with non-vaccine neoantigens, surveillance of chronic viral infections, in vivo or in vitro assessment of cellular immunity, and analysis of innate immunity. Banking genetic material to allow genotyping should be considered particularly if a central repository for samples from different trials can be established.

Pancreas transplantation under alemtuzumab (Campath-1H) and tacrolimus: Correlation between low T-cell responses and infection

BACKGROUND

Alemtuzumab induction and tacrolimus-based immunosuppression has been effective in pancreas transplantation. Despite the encouraging results of this minimalistic approach to immunosuppression, infection still remains a significant cause of morbidity. The Cylex ImmuKnow [corrected] assay was used in this study to compare pancreas recipient clinical states (stable, rejection, infection) with T cell responses.

METHODS

Blood samples were taken from pancreas recipients pretransplant and at approximately three-month intervals posttransplant for analysis of T cell responses. When possible, T cell responses were also quantified during changes in clinical status (infection or rejection).

RESULTS

A range between 100-300 ng/ml adenosine triphosphate (ATP) was found in stable patients (mean 194+/-123, n = 51) with good graft function and no infection or rejection. A low T cell response was highly correlated with infectious states. The fourteen patients with infections/posttransplant lymphoproliferative disease had a mean ATP of 48 ng/ml. Risk hazard analysis showed that patients with ATP levels <100 ng/ml were four to seven times more susceptible to infection compared to stable patients. Four patients with rejection showed a T cell response of 550 ng/ml ATP, which was statistically significant compared to stable patients, although the sampling numbers (9) were too small to be conclusive.

CONCLUSION

The Cylex ImmuKnow [corrected] assay is a valuable tool to more precisely modulate immunosuppression in pancreas transplant patients. In particular, the assay is extremely useful in detecting overly immunosuppressed patients vulnerable to infections.

Biologic therapies in rheumatology: lessons learned, future directions

During the past decade biologic therapies such as monoclonal antibodies and fusion proteins have revolutionized the management of rheumatic disease. By targeting key cytokines and immune cells biologics have provided more specific therapeutic interventions with less immunosuppression. Clinical use, however, has revealed that their theoretical simplicity hides a more complex reality. Efficacy, toxicity and even pharmacodynamic effects can deviate from those predicted, as poignantly illustrated by the catastrophic effects witnessed during the first-into-human administration of TGN1412. This review summarizes lessons gleaned from practical experience and discusses how these can inform future discovery and development of new biologic therapies for rheumatology.

CD52 ligation induces CD4 and CD8 down modulation in vivo and in vitro

To successfully induce donor-specific tolerance after immune depletion, it is essential to understand the residual and recovering immune system in the context of the depleting agent because the properties of such a recovering immune system differ based on the depleting agent used. In this study, we investigate the phenotypic and functional characteristics of T cells exposed to Campath-1H in vivo and in vitro. Recovering T cells demonstrated down modulated surface CD4 and CD8 (by flow cytometry) for up to 45 days after Campath-1H administration. Additionally, these T cells had an activated phenotype. To determine whether this CD4/8 down modulation was due to T-cell activation only or in part due to Campath-1H, whole blood from healthy volunteers was exposed to Campath-1H and the surviving lymphocytes isolated. Flow cytometry revealed a dose-dependent down modulation of CD4/8 without T-cell activation. Additionally, these Campath-1H-treated T cells were immunocompetent as indicated by increased surface CD69 and interleukin-2 (IL-2) production following stimulation by soluble anti-CD3 mAb. In conclusion, Campath-1H by itself down modulates surface CD4 and CD8 without activating T cells.

Rates and predictors of herpes zoster in patients with rheumatoid arthritis and non-inflammatory musculoskeletal disorders

OBJECTIVES

Herpes zoster (HZ) is a common disorder that causes substantial pain and morbidity. We examined its rate and predictors in rheumatoid arthritis (RA) and non-inflammatory musculoskeletal (MSK) disorders to determine if HZ was increased in RA and whether treatment contributed to the risk of HZ.

METHODS

After excluding patients witzh prior HZ, we assessed 10 614 RA and 1721 MSK patients by semi-annual questionnaires during 33 825 patient-years of follow-up. Predictors of HZ were determined by Cox regression and expressed as hazard ratios (HR) and 95% confidence intervals (CI).

RESULTS

The annualized incidence rate per 1000 patient-years was 13.2 (95% CI 11.9-14.5) in RA and 14.6 (95% CI 11.2-18.1) in MSK, and did not differ significantly after adjustment for age and sex. HZ was predicted by impaired functional status, as measured by the Health Assessment Questionnaire (HAQ), [HR 1.3 (95% CI 1.1-1.5)] and by the use of COX-2-specific non-steroidal anti-inflammatory drugs (NSAIDs) [HR 1.3 (95% CI 1.1-1.6)] in RA and MSK. In multivariable analyses in patients with RA, cyclophosphamide HR 4.2 (95% CI 1.6-11.5), azathioprine HR 2.0 (1.2-3.3), prednisone HR 1.5 (1.2-1.8), leflunomide HR 1.4 (1.1-1.8) and COX-2 NSAIDs HR 1.3 (95% CI 1.1-1.6) were significant predictors of HZ.

CONCLUSION

The incidence of HZ is increased in RA and MSK compared with population-based rates. However, the rate of HZ in RA is not increased compared with MSK. After adjustment for severity, various treatments, but not methotrexate or biologics, were risk factors for HZ.

Outcomes at 3 years of a prospective pilot study of Campath-1H and sirolimus immunosuppression for renal transplantation

Campath-1H (alemtuzumab) induction was used for renal transplantation in combination with sirolimus as immunosuppression. We previously reported a high (28%) rate of early rejection with this regimen, and now report 3-year outcomes. Twenty-nine patients were recipients of either deceased donor or non-HLA (Human Leukocyte Antigen) identical living donor primary renal allografts. Clinical parameters including infection, malignancy, kidney function, and kidney histology were followed prospectively for 3 years. Three-year cumulative graft and patient survival were 96% and 100%, respectively. Twenty patients were maintained on steroid-free immunosuppressive regimens, and 15 patients were maintained on monotherapy for immunosuppression (12 on sirolimus). No serious infectious complications were observed and two patients developed basal cell skin cancer. The 3-year results of our initial pilot study demonstrate good graft (96%) and patient (100%) outcomes. Campath-1H induction has yielded a high proportion of patients maintained on immunosuppressive monotherapy (57%) without serious infectious- and no malignancy-related complications. The reported regimen yielded novel insights into both Campath-1H and sirolimus therapy in renal transplantation. Because of the higher incidence of early rejection, we recommend a modified strategy of immunosuppression including a brief course of a calcineurin inhibitor.

Lymphocyte homeostasis following therapeutic lymphocyte depletion in multiple sclerosis

Following lymphocyte depletion, homeostatic mechanisms drive the reconstitution of lymphocytes. We prospectively studied this process in 16 patients for 1 year after a single pulse of treatment with Campath-1H, a humanised anti-CD52 monoclonal antibody. We observed two phases of lymphocyte reconstitution. In the first 6 months after treatment the precursor frequency and proliferation index of the patients' autologous mixed lymphocyte reaction increased; the depleted T cell pool was dominated by memory T cells, especially (CD4+)CD25high T cells, a putative regulatory phenotype; and there was a non-significant rise in peripheral mononuclear cell FoxP3 mRNA expression and fall in constitutive cytokine mRNA expression. In the later phase, from 6-to-12 months after Campath-1H, these changes reversed and there was a rise in ROG mRNA expression. However, total CD4+ numbers remained below 50% of pre-treatment levels at 12 months, perhaps reflecting a failure in homeostasis. This was not due to an impaired IL-7 response, as in rheumatoid arthritis, nor to a lack of IL-7 receptors, which are found on fewer human (CD4+)CD25high than naive cells. We speculate that CCL21 and IL-15 responses to lymphopaenia may be suboptimal in multiple sclerosis.

Emerging biologic therapies in rheumatoid arthritis: cell targets and cytokines

PURPOSE OF REVIEW

Biologic therapy for rheumatoid arthritis targets specific molecules, both cell-bound and soluble, that mediate and sustain the clinical manifestations of this complex disease. The aim of all the therapeutic strategies is to achieve complete and sustained suppression of inflammation, in the absence of unacceptable short-term and long-term toxicity. Despite the success of the currently available biologic inhibitors of tumor necrosis factor-alpha and interleukin-1, a substantial number of rheumatoid arthritis patients are refractory to these treatments. The purpose of this review is to highlight recent clinical trials of emerging biologic treatments for rheumatoid arthritis.

RECENT FINDINGS

T cell co-stimulation has been targeted by the use of cytotoxic T lymphocyte-associated antigen 4-Ig, a genetically engineered fusion protein. In a large controlled clinical trial, this nondepleting approach was shown to achieve impressive clinical responses, without evidence of short-term toxicity. Likewise, rituximab, a B cell-deleting monoclonal antibody, was shown in a controlled clinical trial to have sustained benefit in patients with refractory rheumatoid arthritis. Despite profound B cell depletion with rituximab, there was an acceptable safety profile with this treatment. MRA, a monoclonal antibody that inhibits interleukin-6 by binding to its receptor interleukin-6R, demonstrated clinically significant improvement in rheumatoid arthritis and a particularly impressive reduction in the acute phase response.

SUMMARY

The response of rheumatoid arthritis to a wide spectrum of therapeutic strategies attests to the complexity and heterogeneity of the disease and provides further impetus for studies that use these therapies to enhance our understanding of disease pathogenesis.

Campath-1H use in pediatric renal transplantation

Campath-1H is a humanized, monoclonal antibody directed against CD52 determinants on the surface of human B- and T-cells and monocytes. Reports of Campath-1H use as induction in adult renal transplantation have been encouraging with low rejection rates and minimal adverse events. We report four high risk pediatric kidney transplant patients who received Campath-1H for unique indications with variable results. Children ranged in age from 20 months to 16 years. Immunosuppression regimens varied. Three of four patients experienced acute rejection, two of which were C4d positive. Serial flow cytometry was performed on all four patients. The patient who received only Campath-1H has an absolute lymphocyte count that remains less than 50% of baseline at 12-months post-transplant. In addition, in this patient CD3, CD4, CD8 and CD20 remain less than 50% of baseline. From this initial experience using Campath-1H in pediatric renal transplantation we conclude that; (1) the use of Campath-1H does not prevent recurrence of FSGS, (2) as seen in adults, lack of calcineurin inhibition when using Campath-1H may increase the risk of antibody-mediated rejection and (3) prolonged lymphocyte depletion remains even after a single dose of Campath-1H in children.

Outcome of intensive immunosuppression and autologous stem cell transplantation in patients with severe rheumatoid arthritis is associated with the composition of synovial T cell infiltration

OBJECTIVE

To determine clinical and immunological correlates of high dose chemotherapy (HDC) + autologous stem cell transplantation (ASCT) in patients with severe rheumatoid arthritis (RA), refractory to conventional treatment.

METHODS

Serial samples of peripheral blood and synovial tissue were obtained from seven patients with RA treated with HDC and autologous peripheral blood grafts enriched for CD34+ cells. Disease activity was assessed with the Disease Activity Score (DAS), serum concentrations of C reactive protein (CRP), and human immunoglobulin (HIg) scans, and the extent of immunoablation was determined by immunophenotyping of peripheral blood mononuclear cells, and immunohistochemistry and double immunofluorescence of synovium.

RESULTS

Clinical responders (n = 5) had a larger number of cells at baseline expressing CD3, CD4, CD27, CD45RA, CD45RB, and CD45RO in synovium (p < 0.05), higher activity on HIg scans (p = 0.08), and a trend towards higher concentrations of CRP in serum than non-responders (n = 2). Subsequent remissions and relapses in responders paralleled reduction and re-expression, respectively, of T cell markers. A relatively increased expression of CD45RB and CD45RO on synovial CD3+ T cells was seen after HDC + ASCT. No correlations were found between DAS and changes in B cells or macrophage infiltration or synoviocytes.

CONCLUSIONS

HDC + ASCT results in profound but incomplete immunoablation of both the memory and naïve T cell compartment, which is associated with longlasting clinical responses in most patients. The findings provide strong circumstantial evidence for a role of T cells in established RA, and demonstrate a role for the synovium in post-transplantation T cell reconstitution.

Modulating co-stimulation: a rational strategy in the treatment of rheumatoid arthritis?

Rheumatoid arthritis (RA) is a common destructive inflammatory disease that affects 0.5-1% of the population in many countries. Even though several new treatments have been introduced for patients with RA, a considerable proportion of patients do not benefit from these, and the need for alternative treatment strategies is clear. This review explores the potential for a therapy targeting the adaptive immune system by modulating co-stimulation of T cells with a CTLA4-Ig fusion protein (abatacept).

Interleukin-7 deficiency in rheumatoid arthritis: consequences for therapy-induced lymphopenia

We previously demonstrated prolonged, profound CD4⁺ T-lymphopenia in rheumatoid arthritis (RA) patients following lymphocyte-depleting therapy. Poor reconstitution could result either from reduced de novo T-cell production through the thymus or from poor peripheral expansion of residual T-cells. Interleukin-7 (IL-7) is known to stimulate the thymus to produce new T-cells and to allow circulating mature T-cells to expand, thereby playing a critical role in T-cell homeostasis. In the present study we demonstrated reduced levels of circulating IL-7 in a cross-section of RA patients. IL-7 production by bone marrow stromal cell cultures was also compromised in RA. To investigate whether such an IL-7 deficiency could account for the prolonged lymphopenia observed in RA following therapeutic lymphodepletion, we compared RA patients and patients with solid cancers treated with high-dose chemotherapy and autologous progenitor cell rescue. Chemotherapy rendered all patients similarly lymphopenic, but this was sustained in RA patients at 12 months, as compared with the reconstitution that occurred in cancer patients by 3–4 months. Both cohorts produced naïve T-cells containing T-cell receptor excision circles. The main distinguishing feature between the groups was a failure to expand peripheral T-cells in RA, particularly memory cells during the first 3 months after treatment. Most importantly, there was no increase in serum IL-7 levels in RA, as compared with a fourfold rise in non-RA control individuals at the time of lymphopenia. Our data therefore suggest that RA patients are relatively IL-7 deficient and that this deficiency is likely to be an important contributing factor to poor early T-cell reconstitution in RA following therapeutic lymphodepletion. Furthermore, in RA patients with stable, well controlled disease, IL-7 levels were positively correlated with the T-cell receptor excision circle content of CD4⁺ T-cells, demonstrating a direct effect of IL-7 on thymic activity in this cohort.