Immune complexes as therapy for autoimmunity

Anti-Inflammatory and Immunomodulatory Effect of High-Dose Immunoglobulins in Children: From Approved Indications to Off-Label Use

BACKGROUND

The large-scale utilization of immunoglobulins in patients with inborn errors of immunity (IEIs) since 1952 prompted the discovery of their key role at high doses as immunomodulatory and anti-inflammatory therapy, in the treatment of IEI-related immune dysregulation disorders, according to labelled and off-label indications. Recent years have been dominated by a progressive imbalance between the gradual but constant increase in the use of immunoglobulins and their availability, exacerbated by the SARS-CoV-2 pandemic.

OBJECTIVES

To provide pragmatic indications for a need-based application of high-dose immunoglobulins in the pediatric context.

SOURCES

A literature search was performed using PubMed, from inception until 1st August 2023, including the following keywords: anti-inflammatory; children; high dose gammaglobulin; high dose immunoglobulin; immune dysregulation; immunomodulation; immunomodulatory; inflammation; intravenous gammaglobulin; intravenous immunoglobulin; off-label; pediatric; subcutaneous gammaglobulin; subcutaneous immunoglobulin. All article types were considered.

IMPLICATIONS

In the light of the current imbalance between gammaglobulins' demand and availability, this review advocates the urgency of a more conscious utilization of this medical product, giving indications about benefits, risks, cost-effectiveness, and administration routes of high-dose immunoglobulins in children with hematologic, neurologic, and inflammatory immune dysregulation disorders, prompting further research towards a responsible employment of gammaglobulins and improving the therapeutical decisional process.

Complement component C1q is an immunological rheostat that regulates Fc:Fc[Formula: see text]R interactions

Though binding sites for the complement factor C1q and the canonical fragment crystallizable (Fc) gamma receptors (Fc[Formula: see text]Rs) on immunoglobulin G (IgG) molecules overlap, how C1q decoration of immune complexes (ICs) influences their ability to engage Fc[Formula: see text]Rs remains unknown. In this report, we use recombinant human Fc multimers as stable IC mimics to show that C1q engagement of ICs directly and transiently inhibits their interactions with Fc[Formula: see text]RIII (CD16) on human natural killer (NK) cells. This inhibition occurs by C1q engagement alone as well as in concert with other serum factors. Furthermore, the inhibition of Fc[Formula: see text]RIII engagement mediated by avid binding of C1q to ICs is directly associated with IC size and dependent on the concentrations of both C1q and Fc multimers present. Functionally, C1q-mediated Fc blockade limits the ability of NK cells to induce the upregulation of the cosignaling molecule, 4-1BB (CD137), and to mediate antibody-dependent cell-mediated cytotoxicity (ADCC). Although C1q is traditionally viewed as a soluble effector molecule, we demonstrate that C1q may also take on the role of an "immunologic rheostat," buffering Fc[Formula: see text]R-mediated activation of immune cells by circulating ICs. These data define a novel role for C1q as a regulator of immune homeostasis and add to our growing understanding that complement factors mediate pleiotropic effects.

A novel monoclonal antibody with improved FcγR blocking ability demonstrated non-inferior efficacy compared to IVIG in cynomolgus monkey ITP model at considerably lower dose

Intravenous immunoglobulin (IVIG) is a well-established treatment for various autoimmune and inflammatory diseases. However, the standard dose prescribed for autoimmune diseases, including immune thrombocytopenic purpura (ITP), is 2 g/kg, which is markedly high and leads to a high treatment burden. In this study, we generated fragment crystallizable (Fc)-modified anti-haptoglobin (Hp) monoclonal antibodies with non-inferior efficacy compared to IVIG at considerably lower doses than IVIG, as shown by in vitro experiments. We evaluated binding activity of anti-Hp antibodies to Fc gamma receptors (FcγRs) with ELISA and inhibitory activity against the ADCC reaction. Furthermore, we successfully established a novel cynomolgus monkey ITP model and demonstrated that the anti-Hp antibody exerted its effect in this model with only a single dose. This Fc-modified anti-Hp monoclonal antibody could be a valuable therapeutic replacement for IVIG for the treatment of ITP.

Lupus serum IgG induces microglia activation through Fc fragment dependent way and modulated by B-cell activating factor

BACKGROUND

Neuropsychiatric manifestations are frequent in patients with systemic lupus erythematosus (SLE), yet the etiology and pathogenesis of brain damage in SLE remains unclear. Because the production of autoantibodies, formation and deposition of immunocomplexes are major serological characteristics of SLE, the elevated level of serum immunoglobulin may contribute to brain tissue injury of SLE. To testify this, in this study, we examined whether immunoglobulin G (IgG) in the serum of SLE patients affects the cellular functions in central nervous system and the potential mechanism.

METHODS

In vivo intracerebral injection of SLE-serum in mouse was used to activate microglia and the production of pro-inflammatory cytokine was assessed by ELISA. Sera was divided into IgG and IgG depleted fractions, while IgG was further divided into Fc and Fab fragments to examine which part has an effect on microglia. Flow cytometry, immunofluorescence and quantitative PCR (qPCR) were used to verify the synergistic effect of B-cell activating factor (BAFF) on IgG stimulation of microglia.

RESULTS

We found that IgG in lupus sera can induce M1 activation of brain microglia following intraventricular injection into normal mice, and BAFF facilitates this process. In vitro, we identified that IgG bound to microglia through Fc rather than Fab fragments, and BAFF up-regulated the expression of Fc receptors (FcγR) on the surface of microglia, consequently, promote IgG binding to microglia.

CONCLUSION

Our results suggest that lupus serum IgG causes inflammatory responses of microglia by involving the Fc signaling pathway and the activity could be up-regulated by BAFF. Accordingly, disruption of the FcγR-mediated signaling pathway and blockade of microglia activation may be a therapeutic target in patients with neuropsychiatric lupus erythematosus.

High-Dose Intravenous Immunoglobulin in Skin Autoimmune Disease

The immunomodulatory potential and low incidence of severe side effects of high-dose intravenous immunoglobulin (IVIg) treatment led to its successful application in a variety of dermatological autoimmune diseases over the last two decades. IVIg is usually administered at a dose of 2 g per kg body weight distributed over 2–5 days every 4 weeks. They are most commonly used as a second- or third-line treatment in dermatological autoimmune disease (pemphigus vulgaris, pemphigus foliaceus, bullous pemphigoid, mucous membrane pemphigoid, epidermolysis bullosa acquisita, dermatomyositis, systemic vasculitis, and systemic lupus erythematosus). However, first-line treatment may be warranted in special circumstances like concomitant malignancy, a foudroyant clinical course, and contraindications against alternative treatments. Furthermore, IVIg can be considered first line in scleromyxedema. Production of IVIg for medical use is strictly regulated to ensure a low risk of pathogen transmission and comparable quality of individual batches. More common side effects include nausea, headache, fatigue, and febrile infusion reactions. Serious side effects are rare and include thrombosis and embolism, pulmonary edema, renal failure, aseptic meningitis, and severe anaphylactic reactions. Regarding the mechanism of action, one can discriminate between functions of the Fcγ region and the F(ab)2 region and their effects on a cellular level. These functions are not mutually exclusive, and more than one pathway may contribute to the beneficial effects. Here, we present a historical background, details on manufacturing, hypotheses on the mechanisms of action, information on the clinical application in the abovementioned conditions, and a brief outlook on future directions of IVIg treatment in dermatology.

Antigen-specific antibody Fc glycosylation enhances humoral immunity via the recruitment of complement

HIV-specific broadly neutralizing antibodies (bNAbs) confer protection after passive immunization, but the immunological mechanisms that drive their development are poorly understood. Structural features of bNAbs indicate that they originate from extensive germinal center (GC) selection, which relies on persistent GC activity. However, why a fraction of infected individuals are able to successfully drive more effective affinity maturation is unclear. Delivery of antigens in the form of antibody-immune complexes (ICs), which bind to complement receptors (CRs) or Fc receptors (FcRs) on follicular dendritic cells, represents an effective mechanism for antigen delivery to the GC. We sought to define whether IC-FcR or CR interactions differ among individuals who develop bNAb responses to HIV. Enhanced Fc effector functions and FcR/CR interactions, via altered Fc glycosylation profiles, were observed among individuals with neutralizing antibody responses to HIV compared with those without neutralizing antibody activity. Moreover, both polyclonal neutralizer ICs and monoclonal IC mimics of neutralizer antibodies induced higher antibody titers, higher-avidity antibodies, and expanded GC B cell reactions after immunization of mice via accelerated antigen deposition within B cell follicles in a complement-dependent manner. Thus, these data point to a direct role for altered Fc profile/complement interactions in shaping the maturation of the humoral immune response, providing insights into how GC activity may be enhanced to drive affinity maturation in next-generation vaccine approaches.

Immune complex negatively regulates toll-like receptor 3-triggered tumour necrosis factor α production in B cells

Inappropriate activation of toll-like receptor 3 (TLR3) has been implicated in the pathogenesis of autoimmune diseases, so the negative regulation of TLR3-triggered immune response has received increasing attention. Nonpathogenic immune complex (IC) has been used as treatment for many inflammatory and autoimmune diseases. However, the role of IC in the regulation of TLR3-triggered immune responses and the underlying mechanisms need to be investigated. In this study we demonstrate that IC or intravenous immunoglobulin (Ig) stimulation of B cells attenuates polyinosinic:polycytidylic acid (poly I:C)-induced CD40 expression; IC, but not Ig, can significantly inhibit poly I:C-induced pro-inflammatory tumour necrosis factor α (TNF-α) production by B cells. Moreover, IC/Ig stimulation does not alter the expression of TLR3 in B cells. Further experiments suggest that receptor for the Fc portion of IgGIIb (FcγRIIb) is involved in the suppressive effect of IC on TLR3-mediated TNF-α production, but not CD40 expression. Thus, we provide a new means of negative regulation of TLR3-triggered immune responses in B cells via FcγRIIb, and we provide a new mechanistic explanation of the therapeutic effect of nonpathogenic IC on inflammatory or autoimmune diseases.

Recombinant human IgG1 based Fc multimers, with limited FcR binding capacity, can effectively inhibit complement-mediated disease

There is a lack of effective targeted therapies for the treatment of complement dependent diseases. We developed two recombinant Fc multimers, G207 and G211, with limited ability to interact with low/moderate affinity FcγRs, but with high avidity for C1q. These drugs effectively inhibited complement dependent cytotoxicity (CDC) in vitro, and prevented the deposition of C1q, C3b and MAC, on the surface of Ab-opsonized cells. Importantly, these inhibitory effects were both C1q dependent and independent. In order to determine the biologic relevance of our findings, we evaluated the clinical efficacy of these drugs in three different animal models, acute RBC hemolysis, anti-Thy-1 nephritis and passive Heymann's nephropathy (PHN), in which disease pathophysiology relies preferentially on complement activation. While G207 was protective in the anti-Thy-1 nephritis and PHN models, G211 was protective in all of the models tested and could effectively treat PHN. In the anti-Thy-1 nephritis model, G211 prevented the characteristic histologic changes associated with the disease and limited glomerular deposition of C3. Collectively, these data suggest that "complement preferential" Fc multimers offer a novel approach to the treatment of complement mediated diseases.

Engineering the fragment crystallizable (Fc) region of human IgG1 multimers and monomers to fine-tune interactions with sialic acid-dependent receptors

Multimeric fragment crystallizable (Fc) regions and Fc-fusion proteins are actively being explored as biomimetic replacements for IVIG therapy, which is deployed to manage many diseases and conditions but is expensive and not always efficient. The Fc region of human IgG1 (IgG1-Fc) can be engineered into multimeric structures (hexa-Fcs) that bind their cognate receptors with high avidity. The critical influence of the unique N-linked glycan attached at Asn-297 on the structure and function of IgG1-Fc is well documented; however, whether the N-linked glycan has a similarly critical role in multimeric, avidly binding Fcs, is unknown. Hexa-Fc contains two N-linked sites at Asn-77 (equivalent to Asn-297 in the Fc of IgG1) and Asn-236 (equivalent to Asn-563 in the tail piece of IgM). We report here that glycosylation at Asn-297 is critical for interactions with Fc receptors and complement and that glycosylation at Asn-563 is essential for controlling multimerization. We also found that introduction of an additional fully occupied N-linked glycosylation site at the N terminus at position 1 (equivalent to Asp-221 in the Fc of IgG1) dramatically enhances overall sialic acid content of the Fc multimers. Furthermore, replacement of Cys-575 in the IgM tail piece of multimers resulted in monomers with enhanced sialic acid content and differential receptor-binding profiles. Thus insertion of additional N-linked glycans into either the hinge or tail piece of monomers or multimers leads to molecules with enhanced sialylation that may be suitable for managing inflammation or blocking pathogen invasion.

A fully recombinant human IgG1 Fc multimer (GL-2045) inhibits complement-mediated cytotoxicity and induces iC3b

GL-2045 is a recombinant human immunoglobulin G1 (IgG1)-based Fc multimer designed to recapitulate the anti-inflammatory activities of intravenous immunoglobulin (IVIG) on the innate and adaptive immune responses. We used functional in vitro studies to determine if GL-2045 could mimic the modulatory activity of IVIG on complement activation. GL-2045, at log-order lower concentrations than heat-aggregated IgG (HAGG) and IVIG, protected antibody-opsonized cells from complement-dependent cytotoxicity. These protective effects were completely mediated by the higher order multimer fractions of GL-2045 and were partially dependent upon sequestration of C1q. Exposure of serum to GL-2045 and, to a lesser extent, IVIG, resulted in high levels of C4a, limited levels of C3a, and no C5a. In contrast, HAGG induced high levels of C4a, C3a, and C5a. The means by which GL-2045 governed complement activation was dependent on its ability to augment the function of factor H, alone and in combination with factor I, to indirectly limit the alternative form of C3 convertase, with resultant increases in the anti-inflammatory molecule, the "inactive" form of C3b, called iC3b. Although IVIG, like GL-2045, potentiated factor H function, it also directly inhibited the alternative form of C3 convertase. Our findings help elucidate how IVIG, GL-2045, and HAGG regulate complement function. Furthermore, the capacity of GL-2045 to sequester C1q and augment factor H activity, in combination with its ability to generate activation-induced immunomodulatory complement split products, such as iC3b, make it a viable drug candidate for the treatment of diverse complement-mediated diseases.

Pathogenesis and Therapeutic Mechanisms in Immune Thrombocytopenia (ITP)

Immune thrombocytopenia (ITP) is a complex autoimmune disease characterized by low platelet counts. The pathogenesis of ITP remains unclear although both antibody-mediated and/or T cell-mediated platelet destruction are key processes. In addition, impairment of T cells, cytokine imbalances, and the contribution of the bone marrow niche have now been recognized to be important. Treatment strategies are aimed at the restoration of platelet counts compatible with adequate hemostasis rather than achieving physiological platelet counts. The first line treatments focus on the inhibition of autoantibody production and platelet degradation, whereas second-line treatments include immunosuppressive drugs, such as Rituximab, and splenectomy. Finally, third-line treatments aim to stimulate platelet production by megakaryocytes. This review discusses the pathophysiology of ITP and how the different treatment modalities affect the pathogenic mechanisms.

Advances in the pathophysiology of primary immune thrombocytopenia

OBJECTIVES

Classically, immune thrombocytopenia (ITP) was thought to be caused by the destruction and insufficient production of platelets, as mediated by autoantibodies. More recently other immune mechanisms that contribute to the disease have been discovered. This review attempts to address the main unresolved questions in ITP.

METHODS

We review the most current knowledge of the pathophysiology of ITP. Immunological effects of available therapies are also described.

DISCUSSION

The trigger may be a loss of tolerance due to molecular mimicry with cross-reaction of antibodies arising from infectious agents or drugs, genetic factors, and/or platelet Toll receptors. This loss of tolerance activates autoreactive effector B and T lymphocytes, which in turn initiates platelet destruction, mediated by cytotoxic T lymphocytes and the release of pro-inflammatory cytokines (IL-2/IL-17) by T helper (Th) cells (Th1/Th17). Th2 (anti-inflammatory) and regulatory B (Breg) and Treg cells are also inhibited (with decrease in IL-10/TGF-β), which leads to the disease becoming chronic. Some isotypes of autoantibodies may increase the bleeding risk. Corticosteroids, rituximab, and thrombopoietin receptor agonists (A-TPOs) all increase levels of Tregs and TGF-β. The A-TPOs also increase Breg levels, which could explain why complete remission has been seen in some cases.

CONCLUSION

A better understanding of the immunomodulatory effects of each ITP therapy is needed to best manage the disease.

Major methylation alterations on the CpG markers of inflammatory immune associated genes after IVIG treatment in Kawasaki disease

Background

Kawasaki disease (KD) is an autoimmune disease preferentially attacking children younger than five years worldwide. So far, the principal treatment to KD is the administration of Intravenous immunoglobulin (IVIG). Although DNA methylation plays important regulation roles in diseases, few studies investigated the regulation roles of DNA methylation in KD.

Methods

In this study, we focused not only on the DNA methylation alterations resulted from KD onset but also on DNA methylation alterations resulted from IVIG administration. To do so, we investigated the effects of KD’s onset and IVIG administration on CpG marker’s methylation alterations.

Results

We first found that DNA methylation alterations reflecting disease onset or IVIG administration are contributed mainly by the CpG markers on autosomes. In addition, we also demonstrated that some CpG markers carry methylation alteration among samples, forcing the expression abundance of the downstream genes to be also altered and negatively correlated with methylation profile. Finally, compared with KD’s onset, IVIG administration brings stronger impact on methylation alteration. And, such alterations were conducted mainly by hyper-methylating CpG markers, forcing the corresponding genes to keep lower expression levels. Moreover, the genes regulated by the altered CpG markers with IVIG administration are enriched in the pathways associated with inflammatory immune response.

Conclusions

In summary, our result provides researchers with another way into the regulation mechanism through which IVIG represses excessive inflammatory responses.

Immune complex negatively regulates Toll-like receptor 9-mediated immune responses in B cells through the inhibitory Fc-gamma receptor IIb

Because inappropriate activation of Toll-like receptor 9 (TLR9) may induce pathological damage, negative regulation of the TLR9-triggered immune response has attracted considerable attention. Nonpathogenic immune complex (IC) has been demonstrated to have beneficial therapeutic effects in some kinds of autoimmune diseases. However, the role of IC in the regulation of TLR9-triggered immune responses and the underlying mechanisms remain unclear. In this study, it was demonstrated that IC stimulation of B cells not only suppresses CpG-oligodeoxynucleotide (CpG-ODN)-induced pro-inflammatory IL-6 and IgM κ production, but also attenuates CD40 and CD80 expression. Furthermore, our results suggest that the receptor for the Fc portion of IgG (FcγR) IIb is involved in the suppressive effect of IC on TLR9-mediated CD40, CD80 and IL-6 expression. Finally, it was found that IC down-regulates TLR9 expression in CpG-ODN activated B cells. Our results provide an outline of a new pathway for the negative regulation of TLR9-triggered immune responses in B cells via FcγRIIb. A new mechanistic explanation of the therapeutic effect of nonpathogenic IC on inflammatory and autoimmune diseases is also provided.

Role of B cells and antibodies in acquired immunity against Mycobacterium tuberculosis

Accumulating evidence has documented a role for B cells and antibodies (Abs) in the immunity against Mycobacterium tuberculosis (Mtb). Passive transfer studies with monoclonal antibodies (mAbs) against mycobacterial antigens have shown protection against the tubercle bacillus. B cells and Abs are believed to contribute to an enhanced immune response against Mtb by modulating various immunological components in the infected host including the T-cell compartment. Nevertheless, the extent and contribution of B cells and Abs to protection against Mtb remains uncertain. In this article we summarize the most relevant findings supporting the role of B cells and Abs in the defense against Mtb and discuss the potential mechanisms of protection.

Understanding the role of antibodies in murine infections with Heligmosomoides (polygyrus) bakeri: 35 years ago, now and 35 years ahead

The rodent intestinal nematode H.p.bakeri has played an important role in the exploration of the host-parasite relationship of chronic nematode infections for over six decades, since the parasite was first isolated in the 1950s by Ehrenford. It soon became a popular laboratory model providing a tractable experimental system that is easy to maintain in the laboratory and far more cost-effective than other laboratory nematode-rodent model systems. Immunity to this parasite is complex, dependent on antibodies, but confounded by the parasite's potent immunosuppressive secretions that facilitate chronic survival in murine hosts. In this review, we remind readers of the state of knowledge in the 1970s, when the first volume of Parasite Immunology was published, focusing on the role of antibodies in protective immunity. We show how our understanding of the host-parasite relationship then developed over the following 35 years to date, we propose testable hypotheses for future researchers to tackle, and we speculate on how the new technologies will be applied to enable an increasingly refined understanding of the role of antibodies in host-protective immunity, and its evasion, to be achieved in the longer term.

Platelets in inflammation and immune modulations: functions beyond hemostasis

Platelets play central roles for maintaining the homeostasis of the blood coagulation. As they are also involved in immune responses and host defenses, increasing evidences have suggested that platelets exert other roles beyond their well-recognized function in preventing bleeding. This review is focused on inflammation, allergy and immune modulations of platelets. Platelets conduct immunoregulation through secretion of functional mediators, interaction with various immune cells, endothelial cells and beneficial for the leukocyte infiltration to inflamed/allergic tissues. In these regulations, the leukocytes are influenced by and receiving the signals from platelets. In contrast, rare attentions were focused on platelet regulations by immune system. An intriguingly example in the intravenous immunoglobulin (IVIg) treatment is discussed, in which dendritic cells exert anti-inflammatory effect through platelets. This further suggests that coagulant and immune systems are tightly associated rather than separate entities. The cross-talks between these two systems implicate that platelet therapy may have application beyond thrombosis, and immune interventions may have potentials to treat thrombosis diseases.

The role of intravenous immunoglobulin in the treatment of cerebral vasospasm induced by subarachnoid haemorrhage: an experimental study

OBJECTIVES

The aim of this study was to determine whether intravenous immunoglobulin (IVIG) prevents cerebral vasospasm in rabbits with induced subarachnoid haemorrhage (SAH). The effect of IVIG on apoptosis in the endothelial cells of the basilar artery was also evaluated.

METHODS

Eighteen New Zealand white rabbits were allocated randomly into three groups. SAH was induced by injecting autologous blood into the cisterna magna. Group 1, the control group, was subjected to sham surgery (no induction of SAH). Group 2 had SAH alone and Group 3 had SAH plus IVIG. Three days after treatment, the animals were sacrificed. The basilar artery tissues were analysed histologically and the malondialdehyde levels in the brain stem tissues were evaluated biochemically.

RESULTS

Differences in the histopathological luminal areas and full wall thicknesses in the SAH plus IVIG group and the SAH group were statically insignificant (p > 0.005). The malondialdehyde level was also found to be lower in the IVIG group than in the SAH group, although this difference was not significant (p > 0.005).

CONCLUSION

Although the IVIG treatment was revealed to have no vasodilator effect on the SAH-induced spastic basilar artery, it was shown to have a beneficial effect on the apoptosis of endothelial cells, probably via anti-inflammatory mechanisms.

Treatment with immunoglobulin improves outcome for pediatric liver transplant recipients

Immunoglobulin mitigates autoimmune disease and facilitates acceptance of ABO-incompatible transplanted organs. To test the hypothesis that treatment with immunoglobulin is associated with improved graft survival and a decreased rate of allograft rejection, a cohort study of primary liver transplant recipients in the Studies of Pediatric Liver Transplantation registry was performed. The outcomes of 336 pediatric liver transplant recipients who received immunoglobulin within 7 days of liver transplantation were compared with the outcomes of 1612 recipients who did not receive immunoglobulin. The outcome measures were patient survival, death-free graft survival, and allograft rejection. The Kaplan-Meier probability of patient survival was not different between patients treated with immunoglobulin and patients who did not receive immunoglobulin. Death-free graft survival was increased in patients treated with immunoglobulin (hazard ratio of death-free survival = 0.57, P = 0.014). The probability of allograft rejection at 3 months was 31% for patients treated with immunoglobulin versus 40% for patients who did not receive immunoglobulin (hazard ratio = 0.81, P = 0.02). The proportion of patients with 2 or more episodes of allograft rejection was lower in patients treated with immunoglobulin (13.1% with immunoglobulin versus 19.2% with no immunoglobulin, P = 0.009). Treatment with immunoglobulin was associated with a decreased risk for allograft rejection, whereas use of cyclosporine as the initial immunosuppression and transplantation before 2002 were independently associated with an increased risk of allograft rejection in pediatric liver transplantation recipients. A trend toward a decreased rate of retransplantation was detected in the population that received treatment with immunoglobulin.

Vaccination without autoantigen protects against collagen II-induced arthritis via immune deviation and regulatory T cells

Anti-inflammation immunotherapy has been successfully applied for the treatment of autoimmune diseases. Mucosal vaccines against autoimmune disorders are beneficial by influencing the regulatory compartment of gut and systemic adaptive immune systems. A Salmonella vector expressing colonization factor Ag I (CFA/I), shown to behave as an anti-inflammatory vaccine, stimulates the production of CD4(+)CD25(+) T cells and regulatory cytokines. In this work, we queried whether Salmonella-CFA/I can protect DBA/1 mice from collagen-induced arthritis. The incidence of arthritis and cartilage loss in vaccinated DBA/1 mice was remarkably lower when compared with unprotected mice. Clinical findings were accompanied by the suppression of inflammatory cytokines TNF-alpha, IL-1beta, IL-6, and IL-27. Vaccination evoked a multi-tier response consisting of IL-4 producing Th2 cells, an increased production of TGF-beta by CD4(+) T cells, and suppression of collagen II-specific CD4(+) T cell proliferation. To assess the contribution of Salmonella-CFA/I-primed CD4(+) T cells, adoptive transfer studies with total CD4(+), CD4(+)CD25(-), or CD4(+)CD25(+) T cells were performed 15 days postchallenge. Mice receiving either subset showed reduced disease incidence and low clinical scores; however, mice receiving total CD4(+) T cells showed delayed disease onset by 10 days with reduced clinical scores, reduced IL-17 and IL-27, but enhanced IL-4, IL-10, IL-13, and TGF-beta. Inhibition of TGF-beta or IL-4 compromised protective immunity. These data show that Salmonella-CFA/I vaccination of DBA/1 mice protects against collagen-induced arthritis by stimulating TGF-beta- and IL-4-producing regulatory CD4(+) T cells.

Novel therapeutics for systemic lupus erythematosus

PURPOSE OF REVIEW

This review provides an update on recently explored therapies in systemic lupus erythematosus and introduces novel therapeutic approaches under consideration. Recent advances in our understanding of systemic lupus are highlighted as well, as these must now inform consideration of therapeutics.

RECENT FINDINGS

Many therapeutic strategies have been shown to be beneficial in murine models of lupus. Compounds that inhibit cellular signaling in response to autoantigens or other triggers and protocols that reconstitute the immune repertoire to diminish autoreactivity are now entering clinical trials.

SUMMARY

Requirements for novel approaches in lupus include improved efficacy and lower toxicity than current therapies, with the goal to reduce tissue damage while preserving immunocompetence.

FcgammaRIII-dependent inhibition of interferon-gamma responses mediates suppressive effects of intravenous immune globulin

Intravenous immune globulin (IVIG) suppresses autoantibody-mediated inflammation by inducing and activating the inhibitory Fc receptor FcgammaRIIb and downstream negative signaling pathways. We investigated the effects of IVIG on cellular responses to interferon-gamma (IFN-gamma), a potent macrophage activator that exacerbates inflammation. Our study showed that IVIG blocked IFN-gamma signaling and IFN-gamma-induced gene expression and suppressed IFN-gamma function in vivo during immune responses to Listeria monocytogenes and in an IFN-gamma-enhanced model of immune thrombocytopenic purpura. The mechanism of inhibition of IFN-gamma signaling was suppression of expression of the IFNGR2 subunit of the IFN-gamma receptor. The inhibitory effect of IVIG was mediated at least in part by soluble immune complexes and was dependent on FcgammaRIII but independent of FcgammaRIIb. These results reveal an unexpected inhibitory role for the activating FcgammaRIII in mediating suppression of IFN-gamma signaling and suggest that inhibition of macrophage responses to IFN-gamma contributes to the anti-inflammatory properties of IVIG.

Preventative and therapeutic vaccination to combat an experimental autoimmune kidney disease

We describe a new vaccination method called modified vaccination technique (MVT). The technique is able to achieve downregulation of pathogenic autoimmune events leading to a chronic progressive disorder in rats called slowly progressive Heymann nephritis. Downregulation of immunopathological events is achieved by injections of immune complex (IC) made up of the target native antigen (ag) and specific naturally occurring immunoglobulin M (IgM) antibody (ab) directed against it. Repeated injections of IC maintain high levels of specific circulating IgM autoantibodies (aabs) against the kidney ag. The developing physiologic IgM aabs assist in the catabolism of both modified and unmodified renal ags from the circulation. No disease-causing renal ags in the circulation results in no stimulation of pathogenic immunoglobulin G aab producing cell lines. Such specific targeted therapy leads to termination of disease-causing processes and reestablishment of tolerance. The MVT can be employed both prophylactically and therapeutically with equal effectiveness. A redirected immune response is achieved by specifically stimulating the animals' own IgM-producing cell lines with the injected ICs, resulting in a natural cure. Such ICs are nontoxic and nonirritant and cause no side effects. We surmise that the MVT, employing the appropriate components in each instance, can also be used to treat human ailments.

A case of severe Rh (D) alloimmunization treated by intensive plasma exchange and high-dose intravenous immunoglobulin

BACKGROUND

In extremely severe Rh (D) alloimmunization, during pregnancy, early diagnosis and treatment is essential to avoid hydrops fetalis. Intrauterine transfusion (IUT) is of utmost importance in the prevention of fetal anemia but it is usually feasible only after 20 weeks of pregnancy. Therefore, additional treatment options in early pregnancy are needed.

STUDY DESIGN AND METHODS

A 27-year-old severely D+C immunized woman was admitted at 8 weeks of gestation in her fifth pregnancy with an extremely high concentration of anti-D. Her first pregnancy was uneventful but resulted in D+C alloimmunization. The next two pregnancies were unsuccessful, because of hydrops fetalis resulting in fetal death in pregnancy week 20 and 24, respectively, despite treatment with high-dose intravenous immunoglobulin (IVIG) and IUT treatment. A fourth pregnancy was terminated with legal abortion. The patient was eager and persistent to accomplish a successful pregnancy. Therefore, a combination of treatments consisting of plasma exchange (PE) three times/week and IVIG 100g/week was started in pregnancy week 12. PE was performed 53 times and totally 159L of plasma was exchanged.

RESULTS

The anti-D concentration was 12mug/mL (IAT titer 2000) before start of treatment by PE and IVIG in pregnancy week 12. The concentration of anti-D was gradually reduced to approximately 3mug/mL after only two weeks of treatment and was maintained at that level until pregnancy week 22. In pregnancy week 26 and 27, signs of hydrops were detected by ultrasonography and IUT were performed at each occasion. Sectio was inevitable at pregnancy week 28+1 and a male baby was born: Hb 58g/L (cord sample) and 68g/L (venous sample); weight 1385g; Apgar score=4-5-7; Bilirubin 56-150mmol/L (4h). Exchange transfusion was performed on day two and day five. Phototherapy was also implemented for eight days. The newborn's recovery thereafter was uneventful and complete.

CONCLUSION

A combination of PE and IVIG may be an efficient treatment possible to start in early pregnancy in patients with extremely severe Rh (D) alloimmunization, with a history of hydrops fetalis in previous pregnancies.

Unusual mixed infection of thoracic empyema caused by Mycobacteria tuberculosis, nontuberculosis mycobacteria and Nocardia asteroides in a woman with systemic lupus erythematosus

We report a 45-year-old woman of systemic lupus erythematosus (SLE) with thoracic empyema that was unusually infected by Mycobacterium tuberculosis (MTB), Nontuberculosis mycobacteria (NTM) concomitant with Nocardia asteroides. After a combined treatment of cotrimoxazole, clarithromycin and anti-tuberculosis drugs with a short-term of intravenous immunoglobulin (IVIG), the patient recovered from the critical illness. On the basis of the results in this case, we recommend a thorough survey of the probably concomitant infections of MTB and NTM in an immunocompromised patient with a known N. asteroid infection. In addition, an adjuvant intravenous immunoglobulin therapy may have beneficial effect in the control of infections in an SLE patient.

Efficient inhibition of HIV-1 replication in human immature monocyte-derived dendritic cells by purified anti-HIV-1 IgG without induction of maturation

During mucosal HIV transmission, immature dendritic cells (DCs) present in the mucosa are among the first cellular targets of the virus. Previous studies have analyzed the inhibition of HIV-1 transfer from human mature DCs to T lymphocytes by neutralizing IgG, but so far no in vitro data regarding the capacity of antibodies to inhibit HIV-1 infection of immature DCs have been reported. Here, we found an increased HIV-inhibitory activity of monoclonal IgG and purified polyclonal IgG when immature monocyte-derived dendritic cells (iMDDCs) were used as target cells instead of autologous blood lymphocytes. We showed that FcgammaRII is involved in the mechanism for inhibiting HIV-1 infection of iMDDCs by IgG, whereas no induction of maturation was detected at concentrations of IgG that result in a 90% reduction of HIV replication. After induction of FcgammaRI expression on iMDDCs by IFN-gamma, an augmentation of the HIV-inhibitory activity of IgG, related to the expression of FcgammaRI, was observed. Taken together, our results demonstrate the participation of FcgammaRs in HIV-1 inhibition by IgG when iMDDCs are the targets. We propose that IgG is able to efficiently inhibit HIV-1 replication in iMDDCs and should be one of the components to be induced by vaccination.