Intravenous immunoglobulin therapy affects T regulatory cells by increasing their suppressive function

[Pathophysiology of immune thrombocytopenia]

Immune thrombocytopenia is an autoimmune disease characterized by a peripheral destruction of platelets. B lymphocytes play a key role but pathogenesis is more complex, involving humoral and cellular immunity associated with an inappropriate platelet production. In this article, we review the different pathogenic pathways, leading to new therapeutic strategies.

Guillain-Barré syndrome following H1N1 immunization in a pediatric patient

OBJECTIVE

To report a case of Guillain-Barré syndrome (GBS) following a dose of influenza A (H1N1) vaccine (Arepanrix).

CASE SUMMARY

An 11-year-old boy was admitted to the hospital after presenting with facial diplegia; abdominal, forehead, and thigh pain; and acute cervical pain. He had received the Arepanrix H1N1 subcutaneous vaccine 13 days before symptom onset. The neurologic examination also revealed a symmetric bilateral paralysis of the VIIth cranial nerve and intense pain, proximal weakness of the shoulder girdles and pelvis, and preserved deep tendon reflexes. Cerebrospinal fluid analysis revealed an albuminocytologic dissociation. Therefore, a diagnosis of atypical GBS following vaccination against HINI influenza was made.

DISCUSSION

Based on the clinical evaluation, laboratory test results, neurologic features, and the exclusion of alternative diagnoses, the Naranjo probability scale revealed a probable relationship between the clinical manifestations of GBS and the vaccine against influenza A (H1N1) received by the patient. This is the first published case for the 2009 influenza pandemic in children.

CONCLUSIONS

While recent studies have found inconclusive results on the association between influenza vaccine and GBS, all suspected cases should be published for further evaluation.

Information for healthcare providers on general features of IGIV with emphasis on differences between commercially available products

OBJECTIVE

Intravenous immunoglobulin (IGIV) has provided an essential replacement therapy for primary and secondary immunodeficiencies patients and prophylaxis of infectious diseases in them. It is also used in several autoimmune and chronic inflammatory disorders. An overview of IGIV with information on several commercially available IGIV products is discussed.

DATA SOURCES

Medline databases and literature provided by the manufacturer for each product presented in the manuscript.

STUDY SELECTION

From the vast body of information on IGIV, only those studies were selected that were pertinent to general features of IGIV (as presented below) or information provided by the manufacturer that facilitated comparing one product to the other.

DATA EXTRACTION

Data was extracted on production, and purification procedures, removal of infectious agents, physical and biochemical properties and issues of safety. Data was extracted only for products available in the US.

DATA SYNTHESIS

IGIV is prepared using pooled plasma. The purification of IGIV is a complex and multi-step process. There is a reciprocal relationship between the purity of IgG in the product and the recovery rate from the total plasma. It is quite possible that some of the biological mediators of the inflammatory and immune systems may be present in trace amounts. Screening and removal of blood borne pathogens is necessary and there are several different techniques available. The specifics of the administration are often variable and no consistent pattern or protocol has been used. When limited dosages are required IGIV may be administered subcutaneously. The side effects associated with IGIV are usually mild and self-limiting.

CONCLUSION

There are differences in products produced by different manufacturers. The current data does not provide sufficient detail or information to be able to make specific recommendations for the use of a given commercial preparation in a specific disease state. The use of IGIV is associated with certain common and uncommon side effects. The identification of risk factors that might predispose a patient to developing them have been studied and reported. In choosing a IGIV preparation the user may avoid features that may predispose to certain side effects. Equally important is monitoring of patients during and after the IGIV therapy.

Intravenous immunoglobulins--understanding properties and mechanisms

High-dose intravenous immunoglobulin (IVIg) preparations are used currently for the treatment of autoimmune or inflammatory diseases. Despite numerous studies demonstrating efficacy, the precise mode of action of IVIg remains unclear. Paradoxically, IgG can exert both pro- and anti-inflammatory activities, depending on its concentration. The proinflammatory activity of low-dose IVIg requires complement activation or binding of the Fc fragment of IgG to IgG-specific receptors (FcgammaR) on innate immune effector cells. In contrast, when administered in high concentrations, IVIg has anti-inflammatory properties. How this anti-inflammatory effect is mediated has not yet been elucidated fully, and several mutually non-exclusive mechanisms have been proposed. This paper represents the proceedings of a session entitled 'IVIg--Understanding properties and mechanisms' at the 6th International Immunoglobulin Symposium that was held in Interlaken on 26-28 March 2009. The presentations addressed how IgG may affect the cellular compartment, evidence for IVIg-mediated scavenging of complement fragments, the role of the dimeric fraction of IVIg, the anti-inflammatory properties of the minor fraction of sialylated IgG molecules, and the genetic organization and variation in FcgammaRs. These findings demonstrate the considerable progress that has been made in understanding the mechanisms of action of IVIgs, and may influence future perspectives in the field of Ig therapy.

Frequency of Treg cells is reduced in CVID patients with autoimmunity and splenomegaly and is associated with expanded CD21lo B lymphocytes

INTRODUCTION

Common variable immunodeficiency is a heterogeneous antibody deficiency syndrome with autoimmune and inflammatory complications in a significant proportion of patients. The study was designed to evaluate the role of T regulatory (Treg) cells in common variable immunodeficiency (CVID) patients with autoimmunity.

METHODS

The number and frequency of Treg cells (CD4(+), CD25(hi), Foxp3(+)) were evaluated in patients and controls, and Foxp3 expression in different subgroups of CVID patients with common clinical manifestations was compared.

RESULTS

CVID patients had significantly fewer Treg cells than controls, and low frequency of Treg cells was associated with expansion of CD21(lo) B cells in patients. Patients with autoimmunity had significantly reduced frequency but normal numbers of regulatory T cells, whilst patients with splenomegaly had significant reduction in frequency and number of regulatory T cells.

CONCLUSION

Foxp3 is useful on its own or as an adjunct to classify CVID patients although the possibility of reduction in Treg cells as a secondary phenomenon cannot be excluded.

Current and future immunotherapy in myasthenia gravis

Current therapy for myasthenia gravis is directed towards generalized modulation and suppression of the immune system. These approaches have been extensively studied and are effective in many patients with myasthenia, but at the cost of significant adverse effects due to the global effects on the immune system. Future directions in therapy are geared towards focused immunotherapies that aim to improve outcomes while lessening the burden of side effects. This paper reviews both the current accepted treatments for myasthenia gravis as well as promising targeted therapies in development.

Autoantibodies to the delta-opioid receptor function as opioid agonists and display immunomodulatory activity

In this report, we show that affinity purified human anti-delta opioid receptor (DOR) autoantibodies from IVIG are specific to DOR and possess agonistic properties displayed by their ability to dramatically decrease forskolin stimulated cAMP accumulation. Anti-DOR autoantibody also caused phosphorylation of the opioid receptor. Anti-DOR autoantibody treatment showed a significant reduction in CXCR4 gene expression as well as surface protein expression. In contrast, anti-DOR autoantibody treatment significantly upregulated CCR5 gene and protein expression. The presence of anti-DOR autoantibodies in IVIG and their potent immunomodulatory activity is further evidence to support the cross-talk between the neuroendocrine and immune systems.

Intravenous immunoglobulins induce potentially synergistic immunomodulations in autoimmune disorders

The increase in platelets in patients with immune thrombocytopenia (ITP) by intravenous administration of human immunoglobulin concentrates (IVIG) reflects a therapeutic immunomodulatory intervention targeted at the disturbed immune response in many inflammatory and autoimmune disorders. These immunoglobulin concentrates contain large numbers of antibodies as well as trace levels of various other immunologically active molecules. Clinical and laboratory studies have documented various mechanisms of action of IVIG. The complex network of immunological reactions resulting from the infusion of IVIG includes changes in several cytokines, interactions with dendritic cells, T- and B- lymphocyte effects, macrophage effects, mediated by distinct Fc-gamma receptors. In addition, effects on complement components and apoptosis have also been observed. Synergism between the different elements of the immune response characterizes the beneficial effects of IVIG in inflammatory and autoimmune disorders. They have immunopathogeneses and clinical manifestations which are difficult to define and therefore IVIG treatment indications remain heterogeneous. Dose finding studies are missing for most of the indications of the drug. In future research, defining the appropriate subgroups of patients should be undertaken. This may be accomplished by prospective registries collecting data on large numbers of patients with long-term follow-up. Controlled clinical and laboratory studies may follow based on new, validated patient selection criteria and focused on mechanisms of action, leading to more evidence-based indications.

Targeting Treg cells in situ: emerging expansion strategies for (CD4(+)CD25(+)) regulatory T cells

Recognition of the ability of CD4(+)FoxP3(+) T cells (Treg) to influence the generation of peripheral immune responses has engendered enthusiasm for the development of strategies utilizing these cells to regulate immune responses in clinically important settings including transplantation, autoimmunity and cancer. A number of studies have reported effective regulation utilizing ex-vivo expansion approaches and subsequent transfer of Treg populations in experimental models. This commentary discusses recently emerging strategies to activate and expand Treg cells in situ which include antibodies, antigen presenting cells and the use of IL2 / anti-IL2 antibody complex. The development of reagents which can stimulate and / or remove Treg cells in situ would represent an important advance towards facilitating new opportunities to harness this compartment for the augmentation of 'wanted' or suppression of 'unwanted' immune responses. Simultaneous targeting of multiple molecules on Treg cells may ultimately enable more effective control of this regulatory sector.

A decreased frequency of regulatory T cells in patients with common variable immunodeficiency

Introduction

Common variable immunodeficiency disorder (CVID) is a heterogeneous syndrome, characterized by deficient antibody production and recurrent bacterial infections in addition abnormalities in T cells. CD4⁺CD25^high regulatory T cells (Treg) are essential modulators of immune responses, including down-modulation of immune response to pathogens, allergens, cancer cells and self-antigens.

Objective

In this study we set out to investigate the frequency of Treg cells in CVID patients and correlate with their immune activation status.

Materials and Methods

Sixteen patients (6 males and 10 females) with CVID who had been treated with regular intravenous immunoglobulin and 14 controls were enrolled. Quantitative analyses of peripheral blood mononuclear cells (PBMC) were performed by multiparametric flow cytometry using the following cell markers: CD38, HLA-DR, CCR5 (immune activation); CD4, CD25, FOXP3, CD127, and OX40 (Treg cells); Ki-67 and IFN-γ (intracellular cytokine).

Results

A significantly lower proportion of CD4⁺CD25^highFOXP3 T cells was observed in CVID patients compared with healthy controls (P<0.05). In addition to a higher proportion of CD8⁺ T cells from CVID patients expressing the activation markers, CD38⁺ and HLA-DR⁺ (P<0.05), we observed no significant correlation between Tregs and immune activation.

Conclusion

Our results demonstrate that a reduction in Treg cells could have impaired immune function in CVID patients.

Intravenous immunoglobulin a natural regulator of immunity and inflammation

Intravenous immunoglobulin (IVIG) products are derived from pooled human plasma and have been used for the treatment of primary immunodeficiency disorders for more than 25 years. IVIG products are also effective in the treatment of autoimmune and inflammatory disorders; however, the precise mechanism(s) of action is not known. Recent investigations suggest that IVIG has a much broader ability to regulate cellular immunity including innate and adaptive components. IVIG is also a recently recognized modifier of complement activation and injury. Here, we discuss these important advancements and how this knowledge applies to desensitization protocols and to the treatment of antibody-mediated rejection.

Increased blood plasma concentrations of TGF-beta1 and TGF-beta2 after treatment with intravenous immunoglobulins in childhood autoimmune diseases

Transforming growth factor-beta (TGF-beta), a multifunctional, immunosuppressive cytokine, is shown to be present in substantial amounts in commercially available intravenous immunoglobulin (IVIG) preparations. To assess whether TGF-beta isoforms are changed in the plasma of paediatric patients with childhood autoimmune diseases after IVIG infusion, 17 patients who received over a period of 12 months overall 56 IVIG infusions (Endobulin) were enrolled in a study. High levels of TGF-beta1 (16.95 +/- 8.16 ng/ml) as well as TGF-beta2 (62.71 +/- 9.50 ng/ml) were detected in the used 56 IVIG probes. TGF-beta1 and TGF-beta2 plasma concentrations were measured prior and 120 min after IVIG infusions by specific TGF-beta ELISA. Interestingly, significant increased TGF-beta1 and TGF-beta2 plasma levels were found in patients after treatment with IVIG. This data suggest that a TGF-beta-mediated mechanism of action may accompany other molecular effects of IVIG therapy. The amount of the potent anti-inflammatory TGF-beta isoforms within the IVIG preparations may exert a differentiated view regarding the manifold indications of IVIG therapy.

Intravenous immunoglobulin as add on treatment with mycophenolate mofetil in severe myositis

OBJECTIVES

To report the use of intravenous immunoglobulin (IVIg) and mycophenolate mofetil (MMF) in polymyositis (PM) and dermatomyositis (DM).

METHODS

We performed an open study in PM and DM with active disease. Indications for treatment were: steroid-dependency, refractoriness to steroid and/or immunosuppressants, and life-threatening disease. IVIg was used at 2 g/kg in monthly cycles for six months and then each other month for other three cycles. MMF was slowly titrated to 30 mg/kg/day orally. Parameters employed to follow patients were the Medical Research Council (MRC) scale, the modified Rankin score, CK serum levels and daily prednisone dose.

RESULTS

Seven patients were studied (4PM, 3DM). All were females, with a mean age of 49 years. All of them achieved a complete remission and, at the last follow-up visit, significant differences in MRC score, modified Rankin score, CK levels, and the daily maintenance prednisone dose were documented. No relevant side effects were observed.

CONCLUSION

IVIg as add on treatment with MMF is effective in severe and refractory myositis, moreover as safe and steroid-sparing agent.

Naturally occurring auto-antibodies in homeostasis and disease

Antibodies with germline or close to germline configuration exist in vertebrates, and these so-called 'naturally occurring auto-antibodies' (NAb) are directed to self and altered self components. Such NAbs have been attracting increasing interest because several of them, including some in their recombinant forms, have therapeutic potential. Whereas a large number of IgM and IgG NAbs have tissue homeostatic roles, others modulate and regulate cellular and enzyme properties. This review describes some of these NAbs and emphasizes how these low-titer, low-affinity NAbs interact with self and altered self and show functional potency in homeostasis and regulation, in addition to in diseases such as infarction and systemic inflammatory response syndrome.

A review of the current use of rituximab in autoimmune diseases

Rituximab is a human/murine chimeric monoclonal antibody primarily used for treating non-Hodgkin's B-cell lymphoma. Recently it has also been used in the treatment of several autoimmune diseases. A literature review was conducted to determine the efficacy of rituximab in the treatment of some of these autoimmune diseases. Multiple mechanisms proposed for the rituximab mediated B cell depletion are also discussed. The efficacy of rituximab is well-established and it is FDA approved for treatment of Rheumatoid arthritis. In this review, data on the use of rituximab is presented from 92 studies involving 1197 patients with the following diseases: systemic lupus erythematosus, idiopathic thrombocytopenic purpura, anti-neutrophil cytoplasmic antibody associated vasculitis, Grave's disease, autoimmune hemolytic anemia, pemphigus vulgaris, hemophilia A, cold agglutinin disease, Sjogren's syndrome, graft vs. host disease, thrombotic thrombocytopenic purpura, cryoglobulinemia, IgM mediated neuropathy, multiple sclerosis, neuromyelitis optica, idiopathic membranous nephropathy, dermatomyositis, and opsoclonus myoclonus. The efficacy varies among different autoimmune diseases. The cumulative data would suggest that in the vast majority of studies in this review, RTX has a beneficial role in their treatment. While rituximab is very effective in the depletion of B cells, current research suggests it may also influence other cells of the immune system by re-establishing immune homeostasis and tolerance. The safety profile of RTX reveals that most reactions are infusion related. In patients with autoimmune diseases the incidence of serious and severe side effects is low. Systemic infection still remains a major concern and may result in death.

Modulation of the cellular immune system by intravenous immunoglobulin

Intravenous immunoglobulin (IVIg) is therapeutically used in a variety of immune-mediated diseases. The beneficial effects of IVIg in auto-antibody-mediated diseases can be explained by neutralization, accelerated clearance and prevention of Fcgamma-receptor binding of auto-antibodies. However, the means by which IVIg exerts therapeutic effects in disorders mediated by cellular immunity have remained enigmatic. Clinical improvements, followed by IVIg treatment, often extend beyond the half-life of infused IgG, thereby indicating that IVIg modifies the cellular immune compartment for a prolonged period. Here, we discuss recent advances in the understanding of different, mutually non-exclusive mechanisms of action of IVIg on cells of the innate and adaptive immune system. These mechanisms might explain the beneficial effects of IVIg in certain autoimmune and inflammatory diseases.

Activation of natural regulatory T cells by IgG Fc-derived peptide "Tregitopes"

We have identified at least 2 highly promiscuous major histocompatibility complex class II T-cell epitopes in the Fc fragment of IgG that are capable of specifically activating CD4(+)CD25(Hi)FoxP3(+) natural regulatory T cells (nT(Regs)). Coincubation of these regulatory T-cell epitopes or "Tregitopes" and antigens with peripheral blood mononuclear cells led to a suppression of effector cytokine secretion, reduced proliferation of effector T cells, and caused an increase in cell surface markers associated with T(Regs) such as FoxP3. In vivo administration of the murine homologue of the Fc region Tregitope resulted in suppression of immune response to a known immunogen. These data suggest that one mechanism for the immunosuppressive activity of IgG, such as with IVIG, may be related to the activity of regulatory T cells. In this model, regulatory T-cell epitopes in IgG activate a subset of nT(Regs) that tips the resulting immune response toward tolerance rather than immunogenicity.

Lack of alpha-1 integrin alters lesion morphology during pulmonary Mycobacterium tuberculosis infection

The hallmark of Mycobacterium tuberculosis infection is the granuloma, a highly dynamic immune structure that contains the bacilli during chronic infection. Here, we examined if alpha1beta1 integrin is required in the development and maintenance of the granulomatous structure during pulmonary infection using the alpha1 integrin knockout (alpha1-null) mouse. The alpha1beta1 integrin is expressed on activated macrophages and T cells, and interacts with collagen molecules in the extracellular matrix (ECM), and thus may play a role in the granulomatous process. Following pulmonary infection with virulent M. tuberculosis, lungs of alpha1-null infected mice had striking differences in granuloma structure, as well as distinct and markedly thickened alveolar septae. By day 180, there were regions of cell death within granulomatous lesions, characterized by cellular debris in these mice. To determine if this molecule was necessary for T cell trafficking within the lungs, the expression of CD4, CD44 and CD62L was monitored. The number of activated and IFN-gamma-producing CD4+ T cells increased in the lungs of alpha1-null mice during the chronic phase of infection, although they had decreased concentrations of TNF-alpha and MMP-9. These results suggest that while alpha1beta1 integrin is not required for trafficking or maintenance of T cells in M. tuberculosis infected lungs, it does play a role in granuloma structure and integrity during the chronic phase of infection.

Regulatory T cells and immune computation

The role of Treg in immune regulation is the topic of this Viewpoint series in the European Journal of Immunology (EJI); the question to be discussed in this section is the effector function of Treg in immune regulation. In this manuscript, we take on the following three postulates outlined by Rolf Zinkernagel on the role of Treg in the control of immunity. First, the immune response is regulated primarily by the antigen and not by Treg. Second, immune non-responsiveness results from the deletion of specific receptor-bearing T cells. Third, there is no definitive proof of the existence of specialized Treg that know what is needed for an equilibrated immune response. Herein, we discuss data demonstrating the existence of specialized Treg and therefore arguing against the validity of the first two postulates. However, based on the reactive nature of the immune system, we agree with Rolf's third postulate in that Treg cannot know ahead of time an ideal set-point for immune homeostasis.

What is the contents of the magic draft IVIg?

Intravenous immunoglobulins (IVIg) consist of IgG concentrated from pooled plasma of numerous donors. Their contents is variable, depending in part on the method of preparation. Natural antibodies and natural autoantibodies are prominent in these preparations and their function. Among these, are the idiotype (Id)/anti-Id dimers. Attention has recently been paid to Fc-gamma receptors and sialylation of the IgG from IVIg.

Expanding Tregs with IVIg

In this issue of Blood, Ephrem et al demonstrate that IVIg expands CD4+CD25+FoxP3+ T regulatory cells (Tregs) and enhances their function in vivo and in vitro. Their findings shed new light on the elusive mechanism of action of IVIg in ameliorating autoimmune diseases.