Intravenous immunoglobulin in autoimmune disorders: An insight into the immunoregulatory mechanisms

The use of IVIg in fetal and neonatal alloimmune thrombocytopenia- Principles and mechanisms

Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a rare neonatal disorder that is caused by alloimmunization against platelet antigens during pregnancy. Although rare, affecting only 1 in 1000 live births, it can cause intracranial hemorrhage and other bleeding complications that can lead to miscarriage, stillbirth and life-long neurological complications. One of the gold-standard therapies for at risk pregnancies is the administration of IVIg. Although IVIg has been used in a variety of different disorders for over 40 years, its exact mechanism of action is still unknown. In FNAIT, the majority of its therapeutic effect is thought the be mediated through the neonatal Fc receptor, however other mechanisms cannot be excluded. Due to safety, supply and other concerns that are associated with IVIg use, alternative therapies that could replace IVIg are additionally being investigated. This includes the possibility of a prophylaxis regimen for FNAIT, similarly to what has been successfully used in hemolytic disease of the fetus and newborn for over 50 years.

Disturbed Transcription of TLRs' Negative Regulators and Cytokines Secretion among TLR4- and 9-Activated PBMCs of Agammaglobulinemic Patients

Toll-like receptors (TLRs) are inevitable elements for immunity development and antibody production. TLRs are in close interaction with Bruton's tyrosine kinase which has been found mutated and malfunctioned in the prototype antibody deficiency disease named X-linked agammaglobulinemia (XLA). TLRs' ability was evaluated to induce transcription of TLR-negative regulators, including suppressor of cytokine signaling 1 (SOCS1), interleukin-1 receptor-associated kinase 3 (IRAK-M), tumor necrosis factor alpha-induced protein 3 (TNFAIP3, A20), and Ring finger protein 216 (RNF216), and Tumor necrosis factor-α (TNF-α) and Interferon-α (IFN-α) production via Lipopolysaccharides (LPS) and CpG-A oligodeoxynucleotides (CpG-A ODN). Measured by TaqMan real-time polymerase chain reaction (PCR), meaningfully increased transcripts of SOCS1 and RNF216 were found in XLA peripheral blood mononuclear cells (PBMCs). Also, TLR inductions of XLA have led to similar downregulations in the regulator's transcription which was different from that in healthy donors. Cytokine measurement by enzyme-linked immunosorbent assay (ELISA) revealed a significant lower TNF-α production both before and after LPS. By selected molecules in this study, TLRs' potential defectiveness range expands TLRs expression, downstream signaling, and cytokine production. The results show new potential elements that could play a part in TLRs defect and pathogenesis of agammaglobulinemia as well.

Long-Term Follow-Up after Intravenous Immunoglobulin Therapy in Patients with Severe Ocular Mucous Membrane Pemphigoid Unresponsive to Conventional Therapy

Mucous membrane pemphigoid (MMP) is a heterogeneous group of rare, systemic, autoimmune subepidermal inflammatory disease that affects mucous membranes and the eye. In its most severe forms, this disease needs systemic therapy, usually based on steroids and immunosuppressant agents. In unresponsive cases or in the presence of contraindications or severe side effects due to conventional systemic corticosteroid and/or immunosuppressant therapy, a therapy shift to high-dose intravenous immunoglobulins (IVIg) has been recommended in other reports. This new therapy has proven to be effective in stopping ocular pemphigoid, but the data regarding the long-term effect on the disease activity or reactivation are extremely scarce, so the novel scientific aim of this study was to evaluate the clinical outcomes after a 9-year follow-up in 12 eyes (6 patients) affected by MMP with ocular involvement, successfully treated with IVIg therapy, as previously described in our report published in 2008. The evaluation of ocular and extraocular disease progression was performed at the end of IVIg therapy and at the end of the follow-up period. After 9 years, all the eyes enrolled showed a long-lasting remission of ocular and oral symptoms with a significant steroid-sparing effect. In conclusion, the IVIg has to be considered as a safe and successful alternative therapy in patients with severe ocular mucous membrane pemphigoid; furthermore, this kind of therapy seems to be effective in maintaining the clinical remission by the time.

Kawasaki disease: guidelines of the Italian Society of Pediatrics, part I - definition, epidemiology, etiopathogenesis, clinical expression and management of the acute phase

The primary purpose of these practical guidelines related to Kawasaki disease (KD) is to contribute to prompt diagnosis and appropriate treatment on the basis of different specialists’ contributions in the field. A set of 40 recommendations is provided, divided in two parts: the first describes the definition of KD, its epidemiology, etiopathogenetic hints, presentation, clinical course and general management, including treatment of the acute phase, through specific 23 recommendations.

Their application is aimed at improving the rate of treatment with intravenous immunoglobulin and the overall potential development of coronary artery abnormalities in KD. Guidelines, however, should not be considered a norm that limits treatment options of pediatricians and practitioners, as treatment modalities other than those recommended may be required as a result of peculiar medical circumstances, patient’s condition, and disease severity or complications.

Recognition and management of idiopathic systemic capillary leak syndrome: an evidence-based review

INTRODUCTION

Idiopathic systemic capillary leak syndrome (SCLS) is a unique disorder characterized by episodes of massive systemic leak of intravascular fluid leading to volume depletion and shock. A typical attack of SCLS consists of prodromal, leak and post-leak phases. Complications, such as compartment syndrome and pulmonary edema, usually develop during the leak and post-leak phases respectively. Judicious intravenous hydration and early use of vasopressors is the cornerstone of management in such cases. Areas covered: The purpose of the present review is to provide an up-to-date, evidence-based review of our understanding of SCLS and its management in the light of currently available evidence.

COMMENTARY

Idiopathic SCLS was first described in 1960 and, since then, more than 250 cases have been reported. A large number of cases have been reported over the past one decade, most likely due to improved recognition. In the acute care setting, most patients with SCLS are managed as per the Surviving Sepsis guidelines and receive aggressive volume resuscitation - which is not the optimal management strategy for such patients. There is a need to raise awareness amongst physicians and clinicians in order to improve recognition of this disorder and ensure its appropriate management.

Transcriptome Analysis of Peripheral Blood in Chronic Inflammatory Demyelinating Polyradiculoneuropathy Patients Identifies TNFR1 and TLR Pathways in the IVIg Response

We have studied the response to intravenous immunoglobulins (IVIg) by a transcriptomic approach in 11 chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) patients (CIDP duration = 6 [0.83-6.5] years). RNA was extracted from cells in whole blood collected before and 3 weeks after IVIg treatment, and hybridized on Illumina chips. After RNA quality controls, gene expression was analyzed using statistical tests fitted for microarrays (R software, limma package), and a pathway analysis was performed using DAVID software. We identified 52 genes with expression that varied significantly after IVIg (fold change [FC] > 1.2, P < 0.001, false discovery rate [FDR] <0.05). Among these 52 genes, 7 were related to immunity, 3 were related to the tumor necrosis factor (TNF)-α receptor 1 (TNFR1) pathway (inhibitor of caspase-activated DNase (ICAD): FC = 1.8, P = 1.7E-7, FDR = 0.004; p21 protein-activated kinase 2 [PAK2]: FC = 1.66, P = 2.6E-5, FDR = 0.03; TNF-α-induced protein 8-like protein 1 [TNFAIP8L1]: P = 1.00E-05, FDR = 0.026), and 2 were related to Toll-like receptors (TLRs), especially TLRs 7 and 9, and were implicated in autoimmunity. These genes were UNC93B1 (FC = 1.6, P = 2E-5, FDR = 0.03), which transports TLRs 7 and 9 to the endolysosomes, and RNF216 (FC = 1.5, P = 1E-05, FDR = 0.03), which promotes TLR 9 degradation. Pathway analysis showed that the TNFR1 pathway was significantly lessened by IVIg (enrichment score = 24, Fischer exact test = 0.003). TNF-α gene expression was higher in responder patients than in nonresponders; however, it decreased after IVIg in responders (P = 0.04), but remained stable in nonresponders. Our data suggest the actions of IVIg on the TNFR1 pathway and an original mechanism involving innate immunity through TLRs in CIDP pathophysiology and the response to IVIg. We conclude that responder patients have stronger inflammatory activity that is lessened by IVIg.

Fc Receptors and Fc Receptor-Like Molecules within the Immunoreceptor Family

Receptors for the Fc portion of immunoglobulins (FcRs) account for most cell-mediated biological activities of antibodies. The majority of FcRs are encoded by a set of genes, clustered in the fcr locus, on chromosome 1 in humans and on chromosome 1 and 3 in mice. Eight (in humans) and six (in mice) new genes were found, intermixed with FcR genes in corresponding fcr loci, which encode FcR-like molecules (FcRLs). FcRs and FcRLs are genetically, phylogenetically, structurally, and functionally related. FcRs and FcRLs, however, markedly differ by their ligands, their tissue distribution, and, therefore, by the biological functions they control. A systematic comparison of their biological properties leads to the conclusion that FcRLs are not like FcRs. They altogether form a single family within the immunoreceptor family, whose members fulfill distinct but complementary roles in immunity by differentially controlling innate and adaptive responses.

Potentiation of cytokine-induced proliferation of human Natural Killer cells by intravenous immunoglobulin G

Intravenous IgG (IVIG) therapy can be used for immunomodulation. IL-2 is an immunoregulatory cytokine. We evaluated IVIG modulation of human blood lymphocyte response to IL-2 and other cytokines. Neither IVIG nor low concentrations of IL-2 (3-30U/ml) induced lymphocyte proliferation, but in combination they synergistically enhanced proliferation of NK cells. The CD56(bright) cells expanded more than CD56(dim) NK cells, with 90% of NK cells dividing up to 8 generations by day 6, while <8% of T cells divided. IVIG also potentiated NK cell proliferation with IL-12, IL-15 and IL-18. The IVIG+cytokine-expanded NK cells were less cytotoxic for K562 cells, than NK cells with cytokine alone. IVIG also enhanced interferon-γ production with IL-2, IL-12 and IL-18. In conclusion, IVIG selectively potentiates NK cell proliferation and interferon-γ secretion with IL-2, IL-12, IL-15 and IL-18 in vitro. These findings warrant evaluation in vivo in relation to NK cells and the immunoregulatory actions of IVIG.

Intravenous IgG (IVIG) and subcutaneous IgG (SCIG) preparations have comparable inhibitory effect on T cell activation, which is not dependent on IgG sialylation, monocytes or B cells

IVIG modulates T cell activation in vitro and inflammatory-autoimmune conditions in vivo. Sialylation of IgG, Fc receptor interactions, modulation of monocyte/macrophage/B cell functions have been implicated in IVIG effects. Subcutaneous IgG (SCIG) therapy is increasingly used for IgG replacement but whether these preparations share the effects of IVIG on T cell modulation is not documented. We compared the potency of SCIG-Hizentra™ (20% IgG preparation) with IVIG-Privigen® (10% IgG) for T cell inhibition, and assessed the involvement of IgG sialylation, monocytes and B cells in this process. Human PBMCs or sorted cells were cultured 3-7 days, and T cells were stimulated with immobilized anti-CD3 mAb or Candida antigen. Thymidine incorporation into DNA was quantitated and cytokines assayed by ELISA/Luminex® assay. IVIG and SCIG both dose-dependently (1-20mg/ml) inhibited (up to >80%) T cell proliferation to anti-CD3 mAb. Response to Candida albicans was comparably inhibited by IVIG and SCIG by 50-80% at 10mg/ml with inhibition even at 3mg/ml (P<0.05). These effects were not affected by depletion of sialic acid containing IgG using neuraminidase treatment or lectin affinity chromatography. With anti-CD3 or Candida stimulation, IL-1β, IL-2, IL-5, IL-6, IL-13, GMCSF, TNF-α, interferon-γ (with anti-CD3) and IL-17 (with Candida) levels were suppressed by IVIG or SCIG, with no effect on IL-4, IL-10, IL-12, IL-15 or TGFβ. Monocytes or B cells were not required for IgG-induced suppression of proliferation, in fact depletion of monocytes potentiated the IgG-induced inhibition. Reconstitution with monocytes restored the original inhibitory effect. These data show that IVIG (Privigen®) and SCIG (Hizentra™) have comparable inhibitory effects on T cell activation, which do not require sialylation of IgG. Inhibition is independent of monocytes or B cells. There is a potent suppression of multiple effector cytokines. Like IVIG, SCIG therapy is expected to show immunomodulatory activity.

Fc Receptors in Immune Responses

Antibodies are major molecular effectors of adaptive immune responses. Most, if not all, biological activities of antibodies, however, depend on the functional properties of cells that express receptors for the Fc portion of antibodies (FcR). Most FcR are activating receptors; some are inhibitory. When engaged by antibodies and antigen, the various FcR expressed by a given cell trigger a mixture of positive and negative signals whose integration determines cellular responses. Responses of cell populations can be either protective or pathogenic. As a consequence, FcR are potential target/tools in a variety of diseases including infection, allergy, autoimmune diseases, and cancer.

Impact of intravenous immunoglobulin on the dopaminergic system and immune response in the acute MPTP mouse model of Parkinson's disease

Intravenous immunoglobulin (IVIg) is a blood-derived product, used for the treatment of immunodeficiency and autoimmune diseases. Since a range of immunotherapies have recently been proposed as a therapeutic strategy for Parkinson’s disease (PD), we investigated the effects of an IVIg treatment in a neurotoxin-induced animal model of PD. Mice received four injections of MPTP (15 mg/kg) at 2-hour intervals followed by a 14-day IVIg treatment, which induced key immune-related changes such as increased regulatory T-cell population and decreased CD4⁺/CD8⁺ ratio. The MPTP treatment induced significant 80% and 84% decreases of striatal dopamine concentrations (P < 0.01), as well as 33% and 40% reductions in the number of nigral dopaminergic neurons (P < 0.001) in controls and IVIg-treated mice, respectively. Two-way analyses of variance further revealed lower striatal tyrosine hydroxylase protein levels, striatal homovanillic acid concentrations and nigral dopaminergic neurons (P < 0.05) in IVIg-treated animals. Collectively, our results fail to support a neurorestorative effect of IVIg on the nigrostriatal system in the MPTP-treated mice and even suggest a trend toward a detrimental effect of IVIg on the dopaminergic system. These preclinical data underscore the need to proceed with caution before initiating clinical trials of IVIg in PD patients.

Dense deposit disease in Korean children: a multicenter clinicopathologic study

The purpose of this study was to investigate the clinical, laboratory, and pathologic characteristics of dense deposit disease (DDD) in Korean children and to determine whether these characteristics differ between Korean and American children with DDD. In 2010, we sent a structured protocol about DDD to pediatric nephrologists throughout Korea. The data collected were compared with previously published data on 14 American children with DDD. Korean children had lower 24-hr urine protein excretion and higher serum albumin levels than American children. The light microscopic findings revealed that a higher percentage of Korean children had membranoproliferative glomerulonephritis patterns (Korean, 77.8%; American, 28.6%, P = 0.036), whereas a higher percentage of American children had crescents (Korean, 0%; American, 78.6%, P < 0.001). The findings from the electron microscopy revealed that Korean children were more likely to have segmental electron dense deposits in the lamina densa of the glomerular basement membrane (Korean, 100%; American, 28.6%, P = 0.002); mesangial deposit was more frequent in American children (Korean, 66.7%; American, 100%, P = 0.047). The histological findings revealed that Korean children with DDD were more likely to show membranoproliferative glomerulonephritis patterns than American children. The degree of proteinuria and hypoalbuminemia was milder in Korean children than American children.

Normal IgG downregulates the intracellular superoxide level and attenuates migration and permeability in human aortic endothelial cells isolated from a hypertensive patient

The normal IgG, a circulating antibody, is maintained at a constant level in humans. However, little is known regarding whether normal IgG has effects on the function of vascular endothelial cells. The purpose of this study was to investigate whether IgG affects superoxide (O(2)(·-)) generation and cell permeability in human aortic endothelial cells (HAECs) isolated from a hypertensive patient. The effect of normal human IgG on endothelial cell function was investigated in cultured HAECs isolated from a hypertensive patient who died of stroke. The results demonstrated, for the first time, that normal IgG attenuated the intracellular O(2)(·-) level and decreased cell migration, cell permeability, and stress fiber formation in HAECs. IgG significantly decreased Rac1 activity and NADPH oxidase activity but upregulated Mn superoxide dismutase expression in HAECs, which may contribute to the IgG-induced decrease in O(2)(·-) level. It is noted that AMP-activated protein kinase (AMPK) was activated by IgG, as evidenced by increased phosphorylation of AMPK. Interestingly, inhibition of AMPK by an AMPK inhibitor abolished IgG-induced decreases in Rac1 and NADPH oxidase activities and IgG-induced increases in Mn superoxide dismutase expression, suggesting that AMPK is an important mediator of the IgG-induced regulation of these enzymes. Importantly, inhibition of AMPK activity also prevented the IgG-induced decrease in O(2)(·-) levels, cell migration, cell permeability, and stress fiber formation. Therefore, normal human IgG may protect HAECs via activation of AMPK and subsequent decreases in intracellular O(2)(·-). These findings reveal a previously unidentified role of normal IgG in regulating AMPK and endothelial cell function.

[Intravenous immunoglobulin: immunomodulatory key of the immune system]

The mechanisms of action of intravenous immunoglobulins (IVIG) are complex and mostly reproduce those of the natural immunoglobulin G (IgG) in our organism. The therapeutic doses used range from substitutive (200-400mg/kg of body weight) in immunodeficiencies to high doses (1-2g/kg of body weight) in autoimmune or inflammatory diseases. The paradoxical pro- or anti-inflammatory effects of IVIG are based on the modulation of the expression of activating versus inhibitory Fc receptors, the type and stage of maturation of the target cell. This huge diversity of actions may explain the extensive and varied range of clinical applications of IVIG nowadays (immunodeficiencies, autoimmune diseases, degenerative diseases such as Alzheimer's, and cancer). On the other hand, biological therapies with monoclonal antibodies mostly consist of IgG molecules with unique antigen specificity, and currently represent a therapeutic field expanding in various pathologies including cancer and diseases of immunological basis. The effects of IgG are added to their specific effects on molecules target.

Fc receptor-targeted therapies for the treatment of inflammation, cancer and beyond

The direct or indirect targeting of antibody Fc receptors (FcRs) presents unique opportunities and interesting challenges for the treatment of inflammatory diseases, cancer and infection. Biological responses induced via the Fc portions of antibodies are powerful, complex and unusual, and comprise both activating and inhibitory effects. These properties can be exploited in the engineering of therapeutic monoclonal antibodies to improve their activity in vivo. FcRs have also emerged as key participants in the pathogenesis of several important autoimmune diseases, including systemic lupus erythematosus and rheumatoid arthritis. Therapeutic approaches based on antagonizing FcR function with small molecules or biological drugs such as monoclonal antibodies and recombinant soluble FcR ectodomains have gained momentum. This Review addresses various strategies to manipulate FcR function to overcome immune complex-mediated inflammatory diseases, and considers approaches to improve antibody-based anticancer therapies.

Acquired von Willebrand syndrome associated with monoclonal gammopathy: a single-center study of 36 patients

In this single-center retrospective study, we evaluated the accuracy of laboratory tests in diagnosing acquired von Willebrand syndrome associated with lymphoproliferative disorders in 36 consecutive patients diagnosed at the University Hospital of Nantes, France. We also compared hemostatic treatments in the following groups: 21 patients with Waldenström macroglobulinemia (WM), 14 with monoclonal gammopathy of undetermined significance (MGUS) (10 with IgG-MGUS and 4 with IgM-MGUS), and 1 with IgA multiple myeloma (IgA-MM). The diagnosis was made in 18 (50%) patients during systematic screening, in 6 (17%) during active mild hemorrhage, and in 12 (33%) during an active, severe bleed. Of the laboratory tests studied, only closure times measured on the Platelet Function Analyzer (PFA)-100 device reliably diagnosed the hemostatic problem. There was no relationship between the factor VIII activity (FVIII:C) or von Willebrand factor activity (VWF:RCo) levels and the previous history of hemorrhage described by patients.We studied hemostatic treatment in most patients: IgG-MGUS patients responded well to high-dose intravenous immunoglobulin (IVIg) infusions (1 g/kg per d), although patients with IgM-MGUS did not. Desmopressin infusions were effective in 3 patients with IgG-MGUS and 2 patients with IgM-MGUS when the baseline values were above 10 IU/dL, but levels soon returned to the baseline. The 7 WM patients had a good response to desmopressin. These results confirm the efficacy of IVIg in IgG-MGUS patients and the prominent role of closure time in the diagnosis of acquired von Willebrand syndrome.

Mechanisms of action of intravenous immunoglobulin in inflammatory muscle disease

Intravenous immunoglobulin (IVIG) is a unique immune-modulating therapy that has a wide range of effects on the immune system at multiple levels. This allows it to be used successfully in a variety of immune-mediated, systemic, and neurological disorders, including the inflammatory myopathies. It is likely that the specific action of IVIG varies depending on the underlying pathogenesis of a given disease. In dermatomyositis (DM), IVIG has been shown to diminish the activity of complement and deposition of membrane attack complex on capillaries and muscle fibers, the expression of adhesion molecules, and cytokine production. IVIG also appears to modify gene expression in the muscle of DM patients. The mechanism by which IVIG affects muscle in polymyositis and inclusion body myositis has not been well-studied. However, it may work via suppression of T-cell activation (including cytotoxic T cells) and migration into muscle tissue and alterations in cytokine production. IVIG generally yields the greatest therapeutic benefit in DM and is often of marginal utility in inclusion body myositis. It is generally considered as second-line or adjunctive therapy in the inflammatory myopathies.

Intravenous immunoglobulins are a therapeutic option in the treatment of multiple sclerosis relapse

OBJECTIVE

The objective of the study is to evaluate the efficacy and tolerability of intravenous immunoglobulin (IVIG) monotherapy in the treatment of multiple sclerosis (MS) relapse.

BACKGROUND

High-dose intravenous methylprednisolone (IVMP) and plasmapheresis have been shown to shorten the recovery period of an MS relapse. Options for those who have contraindications for or are unresponsive to these treatments are very limited. Intravenous immunoglobulin has been used experimentally in these situations, even though there are no previous studies on its efficacy as monotherapy in MS relapse.

SUBJECTS AND METHODS

Twelve consecutive MS patients with acute MS relapse were treated with IVIG 0.4 g/kg per day for 5 days, and the next 5 patients received IVMP 1000 mg/d for 3 days. Volumetric brain magnetic resonance imaging (MRI) and clinical evaluation using expanded disability status scale (EDSS) were performed at baseline and at 3 weeks after treatment. EDSS score after 1 year of the treatment was collected from the patient records. MRI evaluation was performed blindly but not the clinical examination and EDSS scoring.

RESULTS

A significant reduction in the volumes of T2-, fluid-attenuated inversion recovery-, and gadolinium-enhanced lesions was detected in the IVIG-treated group, but not in the IVMP-treated patients. The difference between the groups did not reach statistical significance. The EDSS score improved equally in both groups.

CONCLUSIONS

Intravenous immunoglobulin did not show inferiority compared with IVMP in the treatment of an acute MS relapse evaluated clinically and radiologically. Therefore, we suggest that IVIG may be tried as a therapy in acute MS relapse, especially in case of contraindications to IVMP and plasmapheresis.

Therapeutic approaches to multiple sclerosis: an update on failed, interrupted, or inconclusive trials of neuroprotective and alternative treatment strategies

Currently approved multiple sclerosis (MS) therapeutics have a mainly anti-inflammatory mode of action. However, a number of promising clinical trials have been initiated that either focus on neuroprotection or follow completely different treatment strategies. So far, all of these clinical trials have failed to show efficacy or had to be halted prematurely because of unexpected adverse events. Some others show results that are of unknown significance with regard to a reliable assessment of true efficacy versus safety. For example, trials addressing the highly promising sodium channel blockers are under close observation because of potential adverse effects after drug withdrawal. Previously failed therapeutic approaches in MS have indicated that there are discrepancies between the theoretical expectations and practical outcomes of different compounds. Learning from these failures helps to optimize future study designs and to reduce risks to patients. This review summarizes trials on MS treatments since 2001 that failed or were interrupted, attempts to analyze the underlying reasons for failure, and discusses the implications for our current view of MS pathogenesis, clinical practice, and the design of future studies. In order to maintain clarity, this review focuses on neuroprotective and various other treatment strategies. Clinical trials addressing anti-inflammatory research strategies are presented elsewhere.

Can we face the challenge of expanding use of intravenous immunoglobulin in neurology?

The use of high-dose polyclonal intravenous immunoglobulin (IVIG) in the treatment of autoimmune neurological diseases has expanded over the last decade. Based on controlled clinical trials IVIG can be considered currently as the first-line treatment in Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy and multifocal motor neuropathy, and it may be used as a rescue therapy in worsening myasthenia gravis. IVIG is a second-line therapy in dermatomyositis, stiff-person syndrome and pregnancy-associated or postpartum relapses of multiple sclerosis. Although the biological efficacy of IVIG is due to multiple effects on the immune system, many mechanisms are still unknown. The awareness of risks and complications of IVIG therapy has increased, but severe side effects are still considered rare. Due to increasing costs of this treatment, careful selection of patients who will benefit from IVIG is extremely important.

Intravenous immunoglobulin therapy for aspirin-heparinoid-resistant antiphospholipid syndrome

We encountered a woman who had a history of repeated fetal losses and positive tests for lupus anticoagulant, phosphatidylserine-dependent antiprothrombin (aPS/PT) IgG, IgM and kininogen-dependent antiphosphatidylethanolamine (aPE) IgG, IgM. Her previous pregnancy had ended in intrauterine fetal death at 24 weeks of gestation despite a therapy of low-dose aspirin, prednisolone and danaparoid. During the present pregnancy, she was treated with repeated intravenous infusions of immunoglobulin (IVIg) together with low-dose aspirin, prednisolone and heparin. When thrombocytopenia developed, she delivered a female baby weighing 2,152 g at 34 weeks of gestation by cesarean section. Titers of aPS/PT IgM and aPE IgM were reduced or maintained at low levels by repeated IVIg therapies. The IVIg therapy might be effective for aspirin-heparinoid-resistant antiphospholipid syndrome.

[Idiopathic capillary leak syndrome]

Idiopathic capillary leak syndrome (ICLS) is a rare and poorly known condition. Since the first description in 1960, about hundred cases have been reported. A French register that was initiated in 1997 provides a better knowledge of the natural course of the disease and highlights some therapeutic issues. ICLS mainly affects middle-aged adults. The prognosis is poor with a 10-year mortality rate around 34%. Severe crisis and complications occurring in intensive care units account for 80% of the mortality. Diagnosis relies on an almost pathognomonic association: recurrent attacks of hypotension and hemoconcentration with paradoxical hypoalbuminemia. A monoclonal gammopathy is found in about 80% of patients. Physiopathology still remains unclear. Paraprotein toxicity has never been demonstrated. As a result, no evidence-based treatment is available neither for acute crisis nor for prophylaxis. Management of acute episodes is mainly symptomatic. Fluid infusion must be cautious because it can induce complications during the recovery phase. Patient education is a major measure to prevent recurrent attacks. Beta-2 stimulants were reported to reduce the frequency and severity of episodes and were considered as the recommended prophylactic measure. However, early data from the French register suggest that intravenous immunoglobulins are more effective in reducing both frequency and severity of the attacks. Inclusion of patients with ICLS in a register is crucial to improve the knowledge about aetiology and treatment of this disorder.

Polyreactive antibodies in multidonor-derived immunoglobulin G: theory and conclusions drawn from experiments

Multidonor-derived (md) preparations of IgG antibodies, agents of therapeutic potential, contain molecules interacting at clonal concentrations (concns) and with affinities recently estimated to cover a considerable range. Here we demonstrate that polyreactivity of the monomeric molecules represents the essential driving force of formation of the main reaction product, the IgG-dimers. This conclusion is obtained by applying the principles of the law of mass action to dimer formation by polyreactive monomeric reactants. In addition, general interrelationships involving the mean number of reactants per reactor, the experimental dimer portion (w/w) and the mean concentrations of monomers in a polyreactive and monoreactive antibody system are derived. These interrelationships, together with quantitative results obtained from simplified computational kinetic models of polyreactive antibodies, allow to estimate a remarkably high value for the mean number of reactants per reactor, exceeding 60 for the underlying IgG preparation obtained from pooled human plasma units of 5000 donors. Moreover, the potential origin and other consequences of polyreactivity are outlined.

Treatment of scleromyxedema and the dermatoneuro syndrome with intravenous immunoglobulin

Scleromyxedema is a rare disease characterized by extensive mucin deposition with fibrosis, and is associated with a monoclonal gammopathy. Currently there is no consensus on optimal treatment of this potentially fatal disease because of the lack of randomized controlled trials and limited number of case reports. At the time of this writing, 24 cases were published reporting clinical improvement of scleromyxedema with intravenous immunoglobulin. Herein we report a case showing dramatic improvement of scleromyxedema symptoms, both cutaneous and extracutaneous (including the dermatoneuro syndrome), and review the use of intravenous immunoglobulin in the treatment of scleromyxedema. This is a single case. The rarity of scleromyxedema, especially the dermatoneuro syndrome, precludes impedes large trials. In conclusion, increasing evidence supports intravenous immunoglobulin as an effective and relatively safe treatment for both cutaneous and extracutaneous manifestations of scleromyxedema, including the dermatoneuro syndrome.

Therapeutic activities of intravenous immunoglobulins in multiple sclerosis involve modulation of chemokine expression

The objective of this study was to identify genes that are differentially expressed in peripheral T cells of patients with MS exacerbation receiving treatment with IVIG. Using microarray analysis, we identified 360 genes that were at least two-fold up- or down-regulated. The expression of four representative genes (PTGER4, CXCL5, IL11 and CASP2) was confirmed by quantitative PCR. Four of the differentially expressed genes encode chemokines (CXCL3, CXCL5, CCL13 and XCL2) that are involved in directing leukocyte migration. We suggest that the modulation of chemokine expression in peripheral T cells contributes to the beneficial activity of IVIG in patients with MS exacerbation.

Neuroprotection in stroke by complement inhibition and immunoglobulin therapy

Activation of the complement system occurs in a variety of neuroinflammatory diseases and neurodegenerative processes of the CNS. Studies in the last decade have demonstrated that essentially all of the activation components and receptors of the complement system are produced by astrocytes, microglia, and neurons. There is also rapidly growing evidence to indicate an active role of the complement system in cerebral ischemic injury. In addition to direct cell damage, regional cerebral ischemia and reperfusion (I/R) induces an inflammatory response involving complement activation and generation of active fragments, such as C3a and C5a anaphylatoxins, C3b, C4b, and iC3b. The use of specific inhibitors to block complement activation or their mediators such as C5a, can reduce local tissue injury after I/R. Consistent with therapeutic approaches that have been successful in models of autoimmune disorders, many of the same complement inhibition strategies are proving effective in animal models of cerebral I/R injury. One new form of therapy, which is less specific in its targeting of complement than monodrug administration, is the use of immunoglobulins. Intravenous immunoglobulin (IVIG) has the potential to inhibit multiple components of inflammation, including complement fragments, pro-inflammatory cytokine production and leukocyte cell adhesion. Thus, IVIG may directly protect neurons, reduce activation of intrinsic inflammatory cells (microglia) and inhibit transendothelial infiltration of leukocytes into the brain parenchyma following an ischemic stroke. The striking neuroprotective actions of IVIG in animal models of ischemic stroke suggest a potential therapeutic potential that merits consideration for clinical trials in stroke patients.

High-dose intravenous immunoglobulins dramatically reverse systemic capillary leak syndrome

OBJECTIVE

The objective of this study was to report the dramatic improvement of patients with systemic capillary leak syndrome obtained with high-dose intravenous immunoglobulins.

DESIGN

Systemic capillary leak syndrome is a rare and life-threatening disorder characterized by hypotension that can lead to shock, weight gain, hypoalbuminemia, and elevated hematocrit secondary to unexplained episodic capillary fluid extravasation into the interstitial space. Because its cause is unknown, systemic capillary leak syndrome treatment has remained largely supportive.

MAIN RESULTS

Intravenous immunoglobulins administration to a patient with refractory systemic capillary leak syndrome yielded dramatic improvement. The patient is still alive 11 yrs after systemic capillary leak syndrome diagnosis and receives intravenous immunoglobulins monthly. Later, based on that result, intravenous immunoglobulins were successfully given to two other patients during the acute phase of systemic capillary leak syndrome. Both are still alive 8 and 1.5 yrs after receiving intravenous immunoglobulins at the onset of each flare.

CONCLUSIONS

Intravenous immunoglobulins were effective against systemic capillary leak syndrome symptoms in three patients, but their exact mechanism remains unknown. Their immunomodulatory effect merits further investigation.

IgG regulates the CD1 expression profile and lipid antigen-presenting function in human dendritic cells via FcgammaRIIa

Dendritic cells (DCs) process and present bacterial and endogenous lipid antigens in complex with CD1 molecules to T cells and invariant natural killer T (NKT) cells. However, different types of DCs, such as blood myeloid DCs and skin Langerhans cells, exhibit distinct patterns of CD1a, CD1b, CD1c, and CD1d expression. The regulation of such differences is incompletely understood. Here, we initially observed that monocyte-derived DCs cultured in an immunoglobulin-rich milieu expressed CD1d but not CD1a, CD1b, and CD1c, whereas DCs cultured in the presence of low levels of immunoglobulins had an opposite CD1 profile. Based on this, we tested the possibility that immunoglobulins play a central role in determining these differences. IgG depletion and intravenous immunoglobulin (IVIg) add-in experiments strongly supported a role for IgG in directing the CD1 expression profile. Blocking experiments indicated that this effect was mediated by FcgammaRIIa (CD32a), and quantitative polymerase chain reaction data demonstrated that regulation of the CD1 profile occurred at the gene expression level. Finally, the ability of DCs to activate CD1-restricted NKT cells and T cells was determined by this regulatory effect of IgG. Our data demonstrate an important role for FcgammaRIIa in regulating the CD1 antigen presentation machinery of human DCs.

A disease-specific fraction isolated from IVIG is essential for the immunosuppressive effect of IVIG in experimental autoimmune myasthenia gravis

Intravenous immunoglobulin (IVIG) treatment is beneficially used in autoimmune disorders including myasthenia gravis (MG) although its mode of action and active components are still not fully identified. In an attempt to isolate from IVIG a disease-specific suppressive fraction, IVIG was passed on columns of IgG from rats with experimental autoimmune MG (EAMG) or from MG patients. These chromatographies resulted in depletion of the suppressive activity of IVIG on rat EAMG whereas the minute amounts of IgG fractions eluted from the EAMG- or MG-specific columns retained the immunosuppressive activity of IVIG. These results demonstrate that a minor disease-specific immunoglobulin fraction present in IVIG is essential for its suppressive activity.

The use of i.v. IG therapy in dermatology

The intravenous administration of exogenous pooled human immunoglobulin (i.v. IG) was originally licensed as antibody replacement therapy in patients with primary immunodeficiencies and there are currently six FDA-approved uses for this agent. Despite a current lack of FDA approval, off-label treatment of a multitude of dermatologic disorders with i.v. IG has shown exciting potential for this unique treatment modality. The diseases successfully treated with i.v. IG include autoimmune bullous diseases, connective tissue diseases, vasculitides, toxic epidermal necrolysis, and infectious disorders (such as streptococcal toxic shock syndrome). Currently the biggest drawback in the consideration of i.v. IG therapy in dermatologic disorders is the lack of randomized controlled trials. Nevertheless, there is a significant body of evidence demonstrating the efficacy of i.v. IG in patients with dermatologic disorders that are resistant to treatment with standard agents. In summary, i.v. IG constitutes a valuable and potentially life-saving agent in managing patients with a variety of dermatologic disorders under the appropriate circumstances.

Fc-receptors as regulators of immunity

Receptors for immunoglobulins [Fc-receptors (FcRs)] are widely expressed throughout the immune system. By binding to the antibody Fc-portion, they provide a link between the specificity of the adaptive immune system and the powerful effector functions triggered by innate immune effector cells. By virtue of coexpression of activating and inhibitory FcRs on the same cell, they set a threshold for immune cell activation by immune complexes (ICs). Besides their involvement in the efferent phase of an immune response, they are also important for modulating adaptive immune responses by regulating B cell and dendritic cell (DC) activation. Deletion of the inhibitory FcR leads to the loss of tolerance in the humoral immune system and the development of autoimmune disease. Uptake of ICs by FcRs on DCs and the concommitant triggering of activating and inhibitory signaling pathways will determine the strength of the initiated T-cell response. Loss of this balanced signaling results in uncontrolled responses that can lead to the damage of healthy tissues and ultimately to the initiation of autoimmune processes. In this chapter, we will discuss how coexpression of different activating and inhibitory receptors on different immune cells of the innate and adaptive immune system modulates cell activity. Moreover, we will focus on exogenous factors that can influence the balanced triggering of activating and inhibitory FcRs, such as the cytokine milieu and the role of differential antibody glycosylation.

Adjuvant high-dose intravenous immunoglobulin therapy can be easily and safely introduced as an alternative treatment in patients with severe pemphigus vulgaris: a retrospective preliminary study

BACKGROUND

Long-term corticosteroid therapy, often in association with other immunosuppressive agents, is considered the mainstay of pemphigus vulgaris (PV) therapy. Recent evidence has been changing this paradigm as patients who are non-responsive to conventional therapies or who experience severe adverse effects have been successfully treated with high-dose intravenous immunoglobulin (IVIg). However, the shift from conventional therapies to IVIg represents a major challenge in the daily practice of non-experienced clinicians because of potential adverse effects and other issues relevant to IVIg therapy such as the necessity for premedication, selection of cases, modality of infusion, patient monitoring, and the cost and length of hospital stay.

OBJECTIVE

The purpose of this preliminary study was to evaluate and report outcomes of treatment with IVIg in eight selected PV patients meeting clearly defined criteria for initiation of this therapy.

METHODS

Available guidelines for IVIg therapy in patients with autoimmune mucocutaneous blistering diseases were followed. Clinical response, induction and duration of remission, strategies for prevention of adverse effects, and total days of hospital stay in eight patients with severe PV treated with IVIg were retrospectively evaluated.

RESULTS

All patients had an effective clinical response without adverse reactions, leading to a significant corticosteroid-sparing effect.

CONCLUSION

Our results indicate that, when current guidelines are followed, IVIg therapy can be easily and safely introduced as a treatment alternative in patients with severe PV. Careful monitoring of patients, utilization of a multidisciplinary approach, and evaluation of hospital-related issues can help the non-experienced clinician successfully manage patients with severe PV requiring IVIg therapy.

Quantitation of alloantibody concentration can predict patient sensitivity to intravenous immunoglobulin desensitization

Despite the success of intravenous immunoglobulin (IVIg) desensitization to reduce anti-human leukocyte antigen antibodies, its high failure rate and expense limit its usefulness. We speculated that quantitation of alloantibody concentration could allow early identification of IVIg resistant patients. Patients were described as nonresponders (n=3) or responders (n=8). Panel reactive antibodies (PRA) were determined using Flowbeads and concentration calculated as molecules of equivalent soluble fluorochrome (MESF). PRA was equivalent between nonresponders and responders before (97+/-3% vs. 76+/-20%, P=NS) and after 3 IVIg/plasmapheresis (PP) treatments but lower among responders at end-of-treatment (76+/-20% vs. 44+/-15%, P<0.01). In contrast, pretreatment MESFs were higher (333,640+/-241,352 vs. 38,741+/-5,133, P=0.006) among nonresponders than responders. During treatment, MESFs decreased (P<0.05) in 0 of 3 nonresponders vs. 8 of 8 responders. Final MESFs were higher among nonresponders than responders. We report that quantitation of MESFs allows early identification of IVIg/PP resistant patients. This sensitive and inexpensive technique should allow more effective patient selection and reduce the costs associated with desensitization.

Naturally occurring B-cell autoreactivity: A critical overview

In over one century of research in immunology marked progress in the scientific knowledge and the implications derived from it has been made. At the same time several contradictory and seemingly opposing results have been obtained. The term autoimmunity is still conceived by many as a term directly related to an immunopathological state. However, strong evidence exist that not only the immune system is able to recognize self-constituents, but it appears also that this property is essential for homeostasis. Direct or indirect alterations of such self-recognition properties of the immune system may contribute to pathology. In this review, the most recent advances in the field of naturally occurring B-cell autoreactivity in health as well as in disease are presented and discussed.

Dense deposit disease: new insights

PURPOSE OF REVIEW

Dense deposit disease is a rare but devastating disease primarily affecting children. This review focuses on new information regarding the pathophysiology of dense deposit disease, its appearance histopathologically, its relationship to other diseases including macular degeneration and acquired partial lipodystrophy and potential new therapies.

RECENT FINDINGS

The microscopic features of dense deposit disease have been separated into five patterns with only about 25% of patients showing membranoproliferative features. The subtle interplay between genetic changes in complement regulatory proteins and dysregulation of the alternative pathway of complement is now more evident. Haplotype mapping has shown at-risk phenotypes of complement factor H associated with the development of dense deposit disease. Treatment protocols are empiric and not very effective. New information on complement inhibitors and plasma exchange, however, has brought hope for new therapies in the near future.

SUMMARY

Understanding of the pathology and the pathophysiology of dense deposit disease has advanced rapidly in the last decade. New efforts in genetic mapping along with the development of novel inhibitors of the complement system will lead to improved care for patients afflicted with this uncommon condition.

Proteomics of Blood-Based Therapeutics

Blood-based therapeutics are cellular or plasma components derived from human blood. Their production requires appropriate selection and treatment of the donor and processing of cells or plasma proteins. In contrast to clearly defined, chemically synthesized drugs, blood-derived therapeutics are highly complex mixtures of plasma proteins or even more complex cells. Pathogen transmission by the product as well as changes in the integrity of blood constituents resulting in loss of function or immune modulation are currently important issues in transfusion medicine. Protein modifications can occur during various steps of the production process, such as acquisition, enrichment of separate components (e.g. coagulation factors, cell populations), virus inactivation, conservation, and storage. Contemporary proteomic strategies allow a comprehensive assessment of protein modifications with high coverage, offer capabilities for qualitative and even quantitative analysis, and for high-throughput protein identification. Traditionally, proteomics approaches predominantly relied on two-dimensional gel electrophoresis (2-DE). Even if 2-DE is still state of the art, it has inherent limitations that are mainly based on the physicochemical properties of the proteins analyzed; for example, proteins with extremes in molecular mass and hydrophobicity (most membrane proteins) are difficult to assess by 2-DE. These limitations have fostered the development of mass spectrometry centered on non-gel-based separation approaches, which have proven to be highly successful and are thus complementing and even partially replacing 2-DE-based approaches. Although blood constituents have been extensively analyzed by proteomics, this technology has not been widely applied to assess or even improve blood-derived therapeutics, or to monitor the production processes. As proteomic technologies have the capacity to provide comprehensive information about changes occurring during processing and storage of blood products, proteomics can potentially guide improvement of pathogen inactivation procedures and engineering of stem cells, and may also allow a better understanding of factors influencing the immunogenicity of blood-derived therapeutics. An important development in proteomics is the reduction of inter-assay variability. This now allows the screening of samples taken from the same product over time or before and after processing. Optimized preparation procedures and storage conditions will reduce the risk of protein alterations, which in turn may contribute to better recovery, reduced exposure to allogeneic proteins, and increased transfusion safety.

Induction of immune tolerance by oral IVIG

In the last years evidence has been provided for the importance of B cells in the pathogenesis of rheumatoid arthritis (RA). Several studies have supported the concept that humoral immunity, manifested by the production of autoantibodies, such as rheumatoid factors (RFs), plays a significant role in the course of the disease. Specific targeting of autoantibody-producing B cells, such as RF-producing B cells, should therefore be a promising new approach in the treatment of RA. We used a mouse model to induce human RF responses and asked the question whether oral treatment with the antigen (human IgG) recognized by RFs could induce immune tolerance to RF responses. Balb/c mice were orally treated with polyvalent human IgG before and after immunization with insoluble immune complexes (ICs) that triggered the induction of RFs. Serum titers of RFs were significantly reduced after both primary and booster immunization when human IgG was given as a single oral dose or continuously in drinking water. Continuous treatment with human IgG even prevented booster effects on RFs when treatment started after primary immunization. Treatment with IgG fragments provided evidence that the observed effect of human IgG was mediated by the Fc part and not the Fab part of IgG. Furthermore, transfer of spleen cells obtained from mice after oral treatment with human IgG suppressed RF responses in recipient mice. These data give promising indications that oral human IgG might represent an alternative approach for immunosuppressive B-cell targeted therapies in RA.

Mechanisms of action of intravenous immunoglobulin in the treatment of immune thrombocytopenia

Intravenous immunoglobulin (IVIG) is currently used to treat a multitude of autoimmune disorders including immune thrombocytopenic purpura (ITP), yet the mechanism of action of IVIG remains unresolved. Using a murine model of ITP in which IVIG functions therapeutically, our laboratory has addressed such theories as blockade/inhibition of the mononuclear phagocytic system, cytokine regulation, and neutralization of pathogenic autoantibodies mediated by anti-idiotypic antibodies, and these findings will be discussed herein. We have also demonstrated that soluble immune complexes can completely recapitulate the therapeutic effects of IVIG in ITP, and recent work from us has identified activating Fcgamma receptors on CD11c+ dendritic cells as the relevant molecular target of IVIG in the acute resolution of murine immune thrombocytopenia. This and other work to devise antibody-based IVIG alternative therapies will also be addressed.