Immunomodulation by IVIg and the Role of Fc-Gamma Receptors: Classic Mechanisms of Action after all?

89Zr-labeled ImmunoPET targeting the cancer stem cell antigen CD133 using fully-human antibody constructs

BACKGROUND

Cancer stem cells play an important role in driving tumor growth and treatment resistance, which makes them a promising therapeutic target to prevent cancer recurrence. Emerging cancer stem cell-targeted therapies would benefit from companion diagnostic imaging probes to aid in patient selection and monitoring response to therapy. To this end, zirconium-89-radiolabeled immunoPET probes that target the cancer stem cell-antigen CD133 were developed using fully human antibody and antibody scFv-Fc scaffolds.

RESULTS

ImmunoPET probes [89Zr]-DFO-RW03IgG (CA = 0.7 ± 0.1), [89Zr]-DFO-RW03IgG (CA = 3.0 ± 0.3), and [89Zr]-DFO-RW03scFv - Fc (CA = 2.9 ± 0.3) were radiolabeled with zirconium-89 (radiochemical yield 42 ± 5%, 97 ± 2%, 86 ± 12%, respectively) and each was isolated in > 97% radiochemical purity with specific activities of 120 ± 30, 270 ± 90, and 200 ± 60 MBq/mg, respectively. In vitro binding assays showed a low-nanomolar binding affinity of 0.6 to 1.1 nM (95% CI) for DFO-RW03IgG (CA = 0.7 ± 0.1), 0.3 to 1.9 nM (95% CI) for DFO-RW03IgG (CA = 3.0 ± 0.3), and 1.5 to 3.3 nM (95% CI) for DFO-RW03scFv - Fc (C/A = 0.3). Biodistribution studies found that [89Zr]-DFO-RW03scFv - Fc (CA = 2.9 ± 0.3) exhibited the highest tumor uptake (23 ± 4, 21 ± 2, and 23 ± 4%ID/g at 24, 48, and 72 h, respectively) and showed low uptake (< 6%ID/g) in all off-target organs at each timepoint (24, 48, and 72 h). Comparatively, [89Zr]-DFO-RW03IgG (CA = 0.7 ± 0.1) and [89Zr]-DFO-RW03IgG (CA = 3.0 ± 0.3) both reached maximum tumor uptake (16 ± 3%ID/g and 16 ± 2%ID/g, respectively) at 96 h p.i. and showed higher liver uptake (10.2 ± 3%ID/g and 15 ± 3%ID/g, respectively) at that timepoint. Region of interest analysis to assess PET images of mice administered [89Zr]-DFO-RW03scFv - Fc (CA = 2.9 ± 0.3) showed that this probe reached a maximum tumor uptake of 22 ± 1%ID/cc at 96 h, providing a tumor-to-liver ratio that exceeded 1:1 at 48 h p.i. Antibody-antigen mediated tumor uptake was demonstrated through biodistribution and PET imaging studies, where for each probe, co-injection of excess unlabeled RW03IgG resulted in > 60% reduced tumor uptake.

CONCLUSIONS

Fully human CD133-targeted immunoPET probes [89Zr]-DFO-RW03IgG and [89Zr]-DFO-RW03scFv - Fc accumulate in CD133-expressing tumors to enable their delineation through PET imaging. Having identified [89Zr]-DFO-RW03scFv - Fc (CA = 2.9 ± 0.3) as the most attractive construct for CD133-expressing tumor delineation, the next step is to evaluate this probe using patient-derived tumor models to test its detection limit prior to clinical translation.

Phenotype and oxidative burst of low-density neutrophil subpopulations are altered in common variable immunodeficiency patients

Common variable immunodeficiency disorder (CVID) is the most common form of primary antibody immunodeficiency. Due to low antibody levels, CVID patients receive intravenous or subcutaneous immunoglobulin replacement therapy as treatment. CVID is associated with the chronic activation of granulocytes, including an increased percentage of low-density neutrophils (LDNs). In this study, we examined changes in the percentage of LDNs and the expression of their surface markers in 25 patients with CVID and 27 healthy donors (HD) after in vitro stimulation of whole blood using IVIg. An oxidative burst assay was used to assess the functionality of LDNs. CVID patients had increased both relative and absolute LDN counts with a higher proportion of mLDNs compared to iLDNs, distinguished based on the expression of CD10 and CD16. Immature LDNs in the CVID and HD groups had significantly reduced oxidative burst capacity compared to mature LDNs. Interestingly we observed reduced oxidative burst capacity, reduced expression of CD10 after stimulation of WB, and higher expression of PD-L1 in mature LDNs in CVID patients compared to HD cells. Our data indicate that that the functional characteristics of LDNs are closely linked to their developmental stage. The observed reduction in oxidative burst capacity in mLDNs in CVID patients could contribute to an increased susceptibility to recurrent bacterial infections among CVID patients.

Serum immunoglobulin and the threshold of Fc receptor-mediated immune activation

Antibodies can mediate immune recruitment or clearance of immune complexes through the interaction of their Fc domain with cellular Fc receptors. Clustering of antibodies is a key step in generating sufficient avidity for efficacious receptor recognition. However, Fc receptors may be saturated with prevailing, endogenous serum immunoglobulin and this raises the threshold by which cellular receptors can be productively engaged. Here, we review the factors controlling serum IgG levels in both healthy and disease states, and discuss how the presence of endogenous IgG is encoded into the functional activation thresholds for low- and high-affinity Fc receptors. We discuss the circumstances where antibody engineering can help overcome these physiological limitations of therapeutic antibodies. Finally, we discuss how the pharmacological control of Fc receptor saturation by endogenous IgG is emerging as a feasible mechanism for the enhancement of antibody therapeutics.

Production of recombinant human IgG1 Fc with beneficial N-glycosylation pattern for anti-inflammatory activity using genome-edited chickens

Intravenous immunoglobulin (IVIG) is a plasma-derived polyclonal IgG used for treatment of autoimmune diseases. Studies show that α-2,6 sialylation of the Fc improves anti-inflammatory activity. Also, afucosylation of the Fc efficiently blocks FcγRIIIA by increasing monovalent affinity to this receptor, which can be beneficial for treatment of refractory immune thrombocytopenia (ITP). Here, we generated genome-edited chickens that synthesize human IgG1 Fc in the liver and secrete α-2,6 sialylated and low-fucosylated human IgG1 Fc (rhIgG1 Fc) into serum and egg yolk. Also, rhIgG1 Fc has higher affinity for FcγRIIIA than commercial IVIG. Thus, rhIgG1 Fc efficiently inhibits immune complex-mediated FcγRIIIA crosslinking and subsequent ADCC response. Furthermore, rhIgG1 Fc exerts anti-inflammatory activity in a passive ITP model, demonstrating chicken liver derived rhIgG1 Fc successfully recapitulated efficacy of IVIG. These results show that genome-edited chickens can be used as a production platform for rhIgG1 Fc with beneficial N-glycosylation pattern for anti-inflammatory activities.

Intravenous immunoglobulins (IVIG) in severe/critical COVID-19 adult patients

The coronavirus disease 2019 (COVID-19) pandemic has become a huge obstacle to the health system due to the high rate of contagion. It is postulated that intravenous immunoglobulins (IVIG) can lower the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-related inflammation and prevent the development of acute respiratory distress syndrome (ARDS). The main advantages of IVIG treatment might be targeting cytokine storm in severe and critical COVID-19 by influences on complement, innate immune cells, effector T-cells, and Tregs. Randomized clinical trials (RCTs) and non-RCTs evaluating the safety and efficacy of IVIG in patients with severe/critical COVID-19 were performed. It seems that early administration of high-dose IVIG (in the acceleration phase of the disease) in severe or especially critical COVID-19 may be an effective therapeutic option, but there are no strong data to use it routinely. The results regarding mortality reduction are inconclusive. Additionally, IVIG treatment carries a risk of complications that should be considered when initiating treatment. However, given the COVID-19 mortality rate and limited therapeutic options, the use of IVIG is worth considering. This review summarizes the development and highlights recent advances in treatment with IVIG of severe/critically ill COVID-19 patients.

Pathophysiology of myelin oligodendrocyte glycoprotein antibody disease

Myelin Oligodendrocyte Glycoprotein Antibody Disease (MOGAD) is a spectrum of diseases, including optic neuritis, transverse myelitis, acute disseminated encephalomyelitis, and cerebral cortical encephalitis. In addition to distinct clinical, radiological, and immunological features, the infectious prodrome is more commonly reported in MOGAD (37-70%) than NMOSD (15-35%). Interestingly, pediatric MOGAD is not more aggressive than adult-onset MOGAD, unlike in multiple sclerosis (MS), where annualized relapse rates are three times higher in pediatric-onset MS. MOGAD pathophysiology is driven by acute attacks during which T cells and MOG antibodies cross blood brain barrier (BBB). MOGAD lesions show a perivenous confluent pattern around the small veins, lacking the radiological central vein sign. Initial activation of T cells in the periphery is followed by reactivation in the subarachnoid/perivascular spaces by MOG-laden antigen-presenting cells and inflammatory CSF milieu, which enables T cells to infiltrate CNS parenchyma. CD4+ T cells, unlike CD8+ T cells in MS, are the dominant T cell type found in lesion histology. Granulocytes, macrophages/microglia, and activated complement are also found in the lesions, which could contribute to demyelination during acute relapses. MOG antibodies potentially contribute to pathology by opsonizing MOG, complement activation, and antibody-dependent cellular cytotoxicity. Stimulation of peripheral MOG-specific B cells through TLR stimulation or T follicular helper cells might help differentiate MOG antibody-producing plasma cells in the peripheral blood. Neuroinflammatory biomarkers (such as MBP, sNFL, GFAP, Tau) in MOGAD support that most axonal damage happens in the initial attack, whereas relapses are associated with increased myelin damage.

Neutrophils as immune effector cells in antibody therapy in cancer

Tumor-targeting monoclonal antibodies are available for a number of cancer cell types (over)expressing the corresponding tumor antigens. Such antibodies can limit tumor progression by different mechanisms, including direct growth inhibition and immune-mediated mechanisms, in particular complement-dependent cytotoxicity, antibody-dependent cellular phagocytosis, and antibody-dependent cellular cytotoxicity (ADCC). ADCC can be mediated by various types of immune cells, including neutrophils, the most abundant leukocyte in circulation. Neutrophils express a number of Fc receptors, including Fcγ- and Fcα-receptors, and can therefore kill tumor cells opsonized with either IgG or IgA antibodies. In recent years, important insights have been obtained with respect to the mechanism(s) by which neutrophils engage and kill antibody-opsonized cancer cells and these findings are reviewed here. In addition, we consider a number of additional ways in which neutrophils may affect cancer progression, in particular by regulating adaptive anti-cancer immunity.

The neonatal Fc receptor expression during macrophage differentiation is related to autophagy

The neonatal Fc receptor (FcRn) plays a central role in recycling and biodistributing immunoglobulin G. FcRn is also involved in many physiological immune functions as well as pathological immune responses in cancer or autoimmune diseases. Low levels of FcRn in tumor cells and the microenvironment is associated with poor prognosis in non-small cell lung cancers. Among cells that are present in the tumor microenvironment, macrophages express high levels of FcRn. Macrophages are involved in these pathophysiological contexts by their dual differentiation states of pro- or anti-inflammatory macrophages. However, variations in FcRn protein expression have not been described in macrophage subtypes. In this work, we studied FcRn expression in an in vitro model of pro- and anti-inflammatory macrophage differentiation. We demonstrated an inverse relation between FcRn protein and mRNA expression in macrophage populations. Autophagy, which is involved in protein degradation and acquisition of phagocytic function in macrophages, participated in regulating FcRn levels. Intravenous immunoglobulin protected FcRn against autophagosome degradation in anti-inflammatory macrophages. Our data demonstrate that autophagy participates in regulating FcRn expression in pro- and anti-inflammatory macrophages. This finding raises new questions concerning the regulation of FcRn in immune functions.

Nutraceuticals for Complementary Treatment of Multisystem Inflammatory Syndrome in Children: A Perspective from Their Use in COVID-19

Multisystem inflammatory syndrome in children (MIS-C) has been widely reported in some children diagnosed with SARS-CoV-2. Clinical signs of MIS-C are manifested at 2 to 4 weeks after SARS-CoV-2 infection, where elevated biomarkers of inflammation and cardiac dysfunction are the hallmark of this syndrome when infection or exposure to SARS-CoV-2 has been confirmed. However, after two years of acknowledgment, MIS-C treatment is still under research to reach safety and effectiveness in the acute phase in children. Therefore, in this review, we discuss the potential use of natural compounds with antioxidant and anti-inflammatory effects to reduce collateral damage caused by hyperinflammation in MIS-C pathology for new research in treatment and interventions.

Systems biology and artificial intelligence analysis highlights the pleiotropic effect of IVIg therapy in autoimmune diseases with a predominant role on B cells and complement system

Intravenous immunoglobulin (IVIg) is used as treatment for several autoimmune and inflammatory conditions, but its specific mechanisms are not fully understood. Herein, we aimed to evaluate, using systems biology and artificial intelligence techniques, the differences in the pathophysiological pathways of autoimmune and inflammatory conditions that show diverse responses to IVIg treatment. We also intended to determine the targets of IVIg involved in the best treatment response of the evaluated diseases. Our selection and classification of diseases was based on a previously published systematic review, and we performed the disease characterization through manual curation of the literature. Furthermore, we undertook the mechanistic evaluation with artificial neural networks and pathway enrichment analyses. A set of 26 diseases was selected, classified, and compared. Our results indicated that diseases clearly benefiting from IVIg treatment were mainly characterized by deregulated processes in B cells and the complement system. Indeed, our results show that proteins related to B-cell and complement system pathways, which are targeted by IVIg, are involved in the clinical response. In addition, targets related to other immune processes may also play an important role in the IVIg response, supporting its wide range of actions through several mechanisms. Although B-cell responses and complement system have a key role in diseases benefiting from IVIg, protein targets involved in such processes are not necessarily the same in those diseases. Therefore, IVIg appeared to have a pleiotropic effect that may involve the collaborative participation of several proteins. This broad spectrum of targets and 'non-specificity' of IVIg could be key to its efficacy in very different diseases.

A homogeneous bioluminescent immunoassay for parallel characterization of binding between a panel of antibodies and a family of Fcγ receptors

Fc engineering efforts are increasingly being employed to modulate interaction of antibodies with variety of Fc receptors in an effort to improve the efficacy and safety of the therapeutic antibodies. Among the various Fc receptors, Fc gamma receptors (FcγRs) present on variety of immune cells are especially relevant since they can activate multiple effector functions including antibody dependent cellular cytotoxicity (ADCC) and antibody dependent cellular phagocytosis (ADCP). Depending on the desired mechanism of action (MOA) of the antibody, interactions between Fc domain of the antibody and FcγR (denoted as Fc/FcγR) may need to be enhanced or abolished. Therefore, during the antibody discovery process, biochemical methods are routinely used to measure the affinities of Fc/FcγR interactions. To enable such screening, we developed a plate based, simple to use, homogeneous immunoassays for six FcγRs by leveraging a luminescent protein complementation technology (NanoBiT). An added advantage of the NanoBiT immunoassays is their solution-based format, which minimizes well known surface related artifacts associated with traditional biosensor platforms (e.g., surface plasmon resonance and biolayer interferometry). With NanoBiT FcγRs assays, we demonstrate that assays are specific, report IgG subclass specific affinities and detect modulation in Fc/FcγR interactions in response to the changes in the Fc domain. We subsequently screen a panel of therapeutic antibodies including seven monoclonal antibodies (mAbs) and four polyclonal intravenous immunoglobulin (IVIg) products and highlight the advantages of parallel screening method for developing new antibody therapies.

Targeting the CD47-SIRPα Innate Immune Checkpoint to Potentiate Antibody Therapy in Cancer by Neutrophils

Simple Summary

Immunotherapy aims to engage various immune cells in the elimination of cancer cells. Neutrophils are the most abundant leukocytes in the circulation and have unique mechanisms by which they can kill cancer cells opsonized by antibodies. However, neutrophil effector functions are limited by the inhibitory receptor SIRPα, when it interacts with CD47. The CD47 protein is expressed on all cells in the body and acts as a ‘don’t eat me’ signal to prevent tissue damage. Cancer cells can express high levels of CD47 to circumvent tumor elimination. Thus, blocking the interaction between CD47 and SIRPα may enhance anti-tumor effects by neutrophils in the presence of tumor-targeting monoclonal antibodies. In this review, we discuss CD47-SIRPα as an innate immune checkpoint on neutrophils and explore the preliminary results of clinical trials using CD47-SIRPα blocking agents.

Abstract

In the past 25 years, a considerable number of therapeutic monoclonal antibodies (mAb) against a variety of tumor-associated antigens (TAA) have become available for the targeted treatment of hematologic and solid cancers. Such antibodies opsonize cancer cells and can trigger cytotoxic responses mediated by Fc-receptor expressing immune cells in the tumor microenvironment (TME). Although frequently ignored, neutrophils, which are abundantly present in the circulation and many cancers, have demonstrated to constitute bona fide effector cells for antibody-mediated tumor elimination in vivo. It has now also been established that neutrophils exert a unique mechanism of cytotoxicity towards antibody-opsonized tumor cells, known as trogoptosis, which involves Fc-receptor (FcR)-mediated trogocytosis of cancer cell plasma membrane leading to a lytic/necrotic type of cell death. However, neutrophils prominently express the myeloid inhibitory receptor SIRPα, which upon interaction with the ‘don’t eat me’ signal CD47 on cancer cells, limits cytotoxicity, forming a mechanism of resistance towards anti-cancer antibody therapeutics. In fact, tumor cells often overexpress CD47, thereby even more strongly restricting neutrophil-mediated tumor killing. Blocking the CD47-SIRPα interaction may therefore potentiate neutrophil-mediated antibody-dependent cellular cytotoxicity (ADCC) towards cancer cells, and various inhibitors of the CD47-SIRPα axis are now in clinical studies. Here, we review the role of neutrophils in antibody therapy in cancer and their regulation by the CD47-SIRPα innate immune checkpoint. Moreover, initial results of CD47-SIRPα blockade in clinical trials are discussed.

Pathophysiological pathway differences in children who present with COVID-19 ARDS compared to COVID -19 induced MIS-C

COVID-19 has infected more than 275 million worldwide (at the beginning of 2022). Children appear less susceptible to COVID-19 and present with milder symptoms. Cases of children with COVID-19 developing clinical features of Kawasaki-disease have been described. Here we utilise Mass Spectrometry proteomics to determine the plasma proteins expressed in healthy children pre-pandemic, children with multisystem inflammatory syndrome (MIS-C) and children with COVID-19 induced ARDS. Pathway analyses were performed to determine the affected pathways. 76 proteins are differentially expressed across the groups, with 85 and 52 proteins specific to MIS-C and COVID-19 ARDS, respectively. Complement and coagulation activation are implicated in these clinical phenotypes, however there was significant contribution of FcGR and BCR activation in MIS-C and scavenging of haem and retinoid metabolism in COVID-19 ARDS. We show global proteomic differences in MIS-C and COVID-ARDS, although both show complement and coagulation dysregulation. The results contribute to our understanding of MIS-C and COVID-19 ARDS in children.

While rare, SARS-CoV-2-infected children can develop severe COVID-19 (ARDS) or inflammatory syndrome (MIS-C). Here, the authors use proteomics to characterize hundreds of blood proteins and identify key biological pathways that differentiate MIS-C and ARDS.

Enhanced Immunomodulatory Effect of Intravenous Immunoglobulin by Fc Galactosylation and Nonfucosylation

Intravenous immunoglobulin (IVIG) is used as an immunomodulatory agent in the treatment of various autoimmune/inflammatory diseases although its mechanism of action remains elusive. Recently, nonfucosylated IgG has been shown to be preferentially bound to Fcγ receptor IIIa (FcγRIIIa) on circulating natural killer cells; therefore, we hypothesized that nonfucosylated IVIG may modulate immune responses through FcγRIIIa blockade. Here, homogeneous fucosylated or nonfucosylated glycoforms of normal polyclonal IgG bearing sialylated, galactosylated or nongalactosylated Fc oligosaccharides were generated by chemoenzymatic glycoengineering to investigate whether the IgG glycoforms can inhibit antibody-dependent cellular cytotoxicity (ADCC). Among the six IgG glycoforms, galactosylated, nonfucosylated IgG [(G2)₂] had the highest affinity to FcγRIIIa and 20 times higher potency to inhibit ADCC than native IgG. A pilot study of IVIG treatment in mice with collagen antibody-induced arthritis highlighted the low-dose (G2)₂ glycoform of IVIG (0.1 g/kg) as an effective immunomodulatory agent as the 10-fold higher dose of native IVIG. These preliminary results suggest that the anti-inflammatory activity of IVIG is in part mediated via activating FcγR blockade by galactosylated, nonfucosylated IgG and that such nonfucosylated IgG glycoforms bound to FcγRs on immune cells play immunomodulatory roles in health and disease. This study provides insights into improved therapeutic strategies for autoimmune/inflammatory diseases using glycoengineered IVIG and recombinant Fc.

Ten-year population trends of immunoglobulin use, burden of adult antibody deficiency and feasibility of subcutaneous immunoglobulin (SCIg) replacement in Hong Kong Chinese

Background

Adult antibody deficiency remains under-recognised and under-studied - especially among Asian populations. Patterns of immunoglobulin use and the feasibility of subcutaneous immunoglobulin (SCIg) replacement among Chinese patients remains unclear.

Objective

To investigate the trends of immunoglobulin use, burden of adult antibody deficiency and the outcomes of patients on SCIg compared to intravenous immunoglobulin (IVIg) replacement in Hong Kong through a retrospective observational study.

Methods

Population-wide data of immunoglobulin recipients in Hong Kong between 2012 and 2021, and longitudinal clinical data of adult immunodeficiency patients at Queen Mary Hospital were collected and analysed.

Results

Total immunoglobulin consumption and recurrent immunoglobulin recipients increased continuously from 175,512g to 298,514g (ρ=0.99, p<0.001) and 886 to 1,508 (ρ=0.89, p=0.001) between 2012-21 in Hong Kong. Among 469 immunoglobulin recipients at Queen Mary Hospital in 2021, 344 (73.3%) were indicated for replacement. Compared to those on IVIg (n=14), patients on SCIg replacement (n=8) had fewer immunodeficiency-related hospitalisations (IRR=0.11) and shorter duration of hospitalisation stay (IRR=0.10) per year, as well as better quality of life (SF-36v2 Health Survey and Life Quality Index). Estimated annual healthcare cost of SCIg replacement per patient was lower than that of IVIg (HKD196,850 [USD25,096] vs HKD222,136 [USD28,319]).

Conclusion

There was a significantly increasing burden of adult antibody deficiency and immunoglobulin consumption in Hong Kong. SCIg was feasible and more cost-effective when compared to IVIg, with SCIg patients experiencing better clinical outcomes and quality of life. Future prospective studies to confirm the long-term efficacy and superiority of SCIg are required.

The immune landscape of SARS-CoV-2-associated Multisystem Inflammatory Syndrome in Children (MIS-C) from acute disease to recovery

Multisystem inflammatory syndrome in children (MIS-C) is a life-threatening disease occurring several weeks after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Deep immune profiling showed acute MIS-C patients had highly activated neutrophils, classical monocytes and memory CD8+ T-cells, with increased frequencies of B-cell plasmablasts and double-negative B-cells. Post treatment samples from the same patients, taken during symptom resolution, identified recovery-associated immune features including increased monocyte CD163 levels, emergence of a new population of immature neutrophils and, in some patients, transiently increased plasma arginase. Plasma profiling identified multiple features shared by MIS-C, Kawasaki Disease and COVID-19 and that therapeutic inhibition of IL-6 may be preferable to IL-1 or TNF-α. We identified several potential mechanisms of action for IVIG, the most commonly used drug to treat MIS-C. Finally, we showed systemic complement activation with high plasma C5b-9 levels is common in MIS-C suggesting complement inhibitors could be used to treat the disease.

Case Report: Successful Response to Intravenous Immunoglobulin and Steroid Pulses in a Renal Transplant Recipient With Severe Covid-19 Disease and Associated Acute Allograft Failure

The impact of Covid-19 pneumonia caused by SARS-CoV-2 on transplanted populations under chronic immunosuppression seems to be greater than in normal population. Clinical management of the disease, particularly in those patients worsening after a cytokine storm, with or without allograft impairment and using available therapeutic approaches in the absence of specific drugs to fight against the virus, involves a major challenge for physicians. We herein provide evidence of the usefulness of high-dose intravenous immunoglobulin (IVIG) combined with steroid pulses to successfully treat a case of Covid-19 pneumonia in a single-kidney transplanted patient with mechanical ventilation and hemodialysis requirements in the setting of a cytokine storm. A rapid decrease in the serum level of inflammatory cytokines, particularly IL-6, IL-8, TNF-α, MCP-1 and IL-10, as well as of acute-phase reactants such as ferritin, D-dimer and C-reactive protein was observed after the IVIG infusion and methylprednisolone bolus administration with a parallel clinical improvement and progressive allograft function recovery, allowing the patient’s final discharge 40 days after the treatment onset. The immunomodulatory effect of IVIG together with the anti-inflammatory and immunosuppressive potential of steroids could be an alternative strategy to treat severe cases of Covid-19 pneumonia associated with an uncontrolled inflammatory response in transplanted populations.

Adjunctive Immunotherapy With Polyclonal Ig-M Enriched Immunoglobulins for Septic Shock: From Bench to Bedside. The Rationale for a Personalized Treatment Protocol

Septic shock still has a high mortality rate which has not hinted at decreasing in recent years. Unfortunately, randomized trials failed mainly because the septic patient was considered as a homogeneous entity. All this creates a sort of therapeutic impotence in everyday clinical practice in treating patients with septic shock. The need to customize therapy on each patient with sepsis has now become an established necessity. In this scenario, adjuvant therapies can help if interpreted as modulators of the immune system. Indeed, the host's immune response differs from patient to patient based on the virulence of the pathogen, comorbidity, infection site, and prolonged hospitalization. In this review, we summarize the rationale for using immunoglobulins as an adjunctive treatment. Furthermore, we would like to suggest a possible protocol to personalize treatment in the different clinical scenarios of the host's response to serious infectious events.

Childhood Multisystem Inflammatory Syndrome: An Emerging Disease with Prominent Cardiovascular Involvement-A Scoping Review

Multisystem inflammatory syndrome in children (MIS-C) or paediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 (PIMS-TS) is an emerging disease in children affected with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection and thought to be an immune-mediated post-infectious complication of SARS-CoV-2. The disease presentation is similar to Kawasaki disease but has certain distinguishing features. The exact pathogenesis is still not clear but an aberrant immune response, antibody-mediated vascular damage and virus-mediated abnormal type I and III interferon-gamma response are thought to be responsible. Most children who are previously healthy present after 2–4 weeks of SARS-CoV-2 infections with febrile illness of short duration with prominent gastrointestinal, cardiac and hematologic manifestations, progressing to vasoplegic shock, requiring vasopressor therapy. Cardiovascular involvement is prominently marked by acute myocardial injury/myocarditis and the development of coronary artery aneurysms. Laboratory markers of inflammation are elevated uniformly. Most children require intensive care, and few need invasive ventilation. The treatment mainly consists of anti-inflammatory and immunomodulatory therapy like intravenous immunoglobulins and steroids. The overall prognosis is good and reported mortality rates are 0–4%.

Immunoglobulin G Glycosylation Changes in Aging and Other Inflammatory Conditions

Among the multiple roles played by protein glycosylation, the fine regulation of biological interactions is one of the most important. The asparagine 297 (Asn₂₉₇) of IgG heavy chains is decorated by a diantennary glycan bearing a number of galactose and sialic acid residues on the branches ranging from 0 to 2. In addition, the structure can present core-linked fucose and/or a bisecting GlcNAc. In many inflammatory and autoimmune conditions, as well as in metabolic, cardiovascular, infectious, and neoplastic diseases, the IgG Asn₂₉₇-linked glycan becomes less sialylated and less galactosylated, leading to increased expression of glycans terminating with GlcNAc. These conditions alter also the presence of core-fucose and bisecting GlcNAc. Importantly, similar glycomic alterations are observed in aging. The common condition, shared by the above-mentioned pathological conditions and aging, is a low-grade, chronic, asymptomatic inflammatory state which, in the case of aging, is known as inflammaging. Glycomic alterations associated with inflammatory diseases often precede disease onset and follow remission. The aberrantly glycosylated IgG glycans associated with inflammation and aging can sustain inflammation through different mechanisms, fueling a vicious loop. These include complement activation, Fcγ receptor binding, binding to lectin receptors on antigen-presenting cells, and autoantibody reactivity. The complex molecular bases of the glycomic changes associated with inflammation and aging are still poorly understood.

Molecular Mechanisms of Antibody-Mediated Rejection and Accommodation in Organ Transplantation

Antibody-mediated rejection (ABMR) in organ transplantation has been recognized as the main cause of graft rejection. Binding of donor-specific HLA antibody (DSA) and A/B blood type antibody on graft endothelial cells causes complement-dependent tissue damage. C4d, a product of the complement cascade, has long been an indicator of graft tissue damage in graft endothelial cells. By contrast, recent evidences indicated histological findings of ABMR without C4d deposition in many cases and Banff classification criteria included a category of C4d-negative ABMR. Several mechanisms have been proposed for complement-independent tissue injury in the presence of DSA. It is well known that activated monocytes and macrophages infiltrate into graft tissues. The inflammatory environment triggered by the binding of DSA to endothelial cells alone can induce an allo-reaction of CD4 T-cells via graft endothelial cell HLA-class II. Accommodation is a condition that no rejections occur even in the presence of an antibody against donor organs and becomes attracting considerable attention as a therapeutic strategy to acquire long-term survival of the transplanted organs. Several recent publications have suggested some mechanistic insights about graft accommodation, including the upregulation of antioxidant, anti-apoptotic, and complement regulatory proteins genes via activation of PI3K/AKT survival signal or inactivation of extracellular signal-regulated protein kinase pro-inflammatory signals after DSA and anti-A/B antibody ligation on endothelial cells.

Strategies for Targeting SARS CoV-2: Small Molecule Inhibitors-The Current Status

Severe Acute Respiratory Syndrome-Corona Virus-2 (SARS-CoV-2) induced Coronavirus Disease - 19 (COVID-19) cases have been increasing at an alarming rate (7.4 million positive cases as on June 11 2020), causing high mortality (4,17,956 deaths as on June 11 2020) and economic loss (a 3.2% shrink in global economy in 2020) across 212 countries globally. The clinical manifestations of this disease are pneumonia, lung injury, inflammation, and severe acute respiratory syndrome (SARS). Currently, there is no vaccine or effective pharmacological agents available for the prevention/treatment of SARS-CoV2 infections. Moreover, development of a suitable vaccine is a challenging task due to antibody-dependent enhancement (ADE) and Th-2 immunopathology, which aggravates infection with SARS-CoV-2. Furthermore, the emerging SARS-CoV-2 strain exhibits several distinct genomic and structural patterns compared to other coronavirus strains, making the development of a suitable vaccine even more difficult. Therefore, the identification of novel small molecule inhibitors (NSMIs) that can interfere with viral entry or viral propagation is of special interest and is vital in managing already infected cases. SARS-CoV-2 infection is mediated by the binding of viral Spike proteins (S-protein) to human cells through a 2-step process, which involves Angiotensin Converting Enzyme-2 (ACE2) and Transmembrane Serine Protease (TMPRSS)-2. Therefore, the development of novel inhibitors of ACE2/TMPRSS2 is likely to be beneficial in combating SARS-CoV-2 infections. However, the usage of ACE-2 inhibitors to block the SARS-CoV-2 viral entry requires additional studies as there are conflicting findings and severe health complications reported for these inhibitors in patients. Hence, the current interest is shifted toward the development of NSMIs, which includes natural antiviral phytochemicals and Nrf-2 activators to manage a SARS-CoV-2 infection. It is imperative to investigate the efficacy of existing antiviral phytochemicals and Nrf-2 activators to mitigate the SARS-CoV-2-mediated oxidative stress. Therefore, in this review, we have reviewed structural features of SARS-CoV-2 with special emphasis on key molecular targets and their known modulators that can be considered for the development of NSMIs.

Responsiveness to i.v. immunoglobulin therapy in patients with toxic epidermal necrolysis: A novel pharmaco-immunogenetic concept

Toxic epidermal necrolysis (TEN) represents a rare drug-induced autoimmune reaction with delayed-type hypersensitivity that initiates the process of developing massive keratinocyte apoptosis, dominantly in the dermoepidermal junction. Although the etiopathophysiology has not yet been fully elucidated, the binding of Fas ligand (FasL, CD95L) to the Fas receptor (CD95) was shown to play a key role in the induction of apoptosis in this syndrome. The knowledge of the role of immunoglobulin G (IgG) in inhibition of Fas-mediated apoptosis contributed to the introduction of i.v. Ig (IVIg) in the therapy of TEN patients. Despite great enthusiasm for this therapy at the end of the 1990s, subsequent studies in various populations and meta-analyses could not unequivocally confirm the efficacy of the IVIg-based treatment concept. Today, therefore, we are faced with the dilemmas of how to adjust therapy of TEN patients most effectively, which patients could benefit from IVIg therapy and what dose of the preparation should be administrated. The ground-breaking question is: do the host genetic profiles influence the responsiveness and side-effects of IVIg therapy in TEN patients? Based on recent pharmacological, immunological and genetic findings, we suggest that the variability of IVIg therapy outcomes in TEN patients may be related to functional variants in Fas, FasL and Fc-γ receptor genes. This novel concept could lead to improved quality of care for patients with TEN, facilitating personalized therapy to reduce mortality.

Acute and Chronic Dosing of a High-Affinity Rat/Mouse Chimeric Transferrin Receptor Antibody in Mice

Non-invasive brain delivery of neurotherapeutics is challenging due to the blood-brain barrier. The revived interest in transferrin receptor antibodies (TfRMAbs) as brain drug-delivery vectors has revealed the effect of dosing regimen, valency, and affinity on brain uptake, TfR expression, and Fc-effector function side effects. These studies have primarily used monovalent TfRMAbs with a human constant region following acute intravenous dosing in mice. The effects of a high-affinity bivalent TfRMAb with a murine constant region, without a fusion partner, following extravascular dosing in mice are, however, not well characterized. Here we elucidate the plasma pharmacokinetics and safety of a high-affinity bivalent TfRMAb with a murine constant region following acute and chronic subcutaneous dosing in adult C57BL/6J male mice. Mice received a single (acute dosing) 3 mg/kg dose, or were treated for four weeks (chronic dosing). TfRMAb and control IgG1 significantly altered reticulocyte counts following acute and chronic dosing, while other hematologic parameters showed minimal change. Chronic TfRMAb dosing did not alter plasma- and brain-iron measurements, nor brain TfR levels, however, it significantly increased splenic-TfR and -iron. Plasma concentrations of TfRMAb were significantly lower in mice chronically treated with IgG1 or TfRMAb. Overall, no injection related reactions were observed in mice.

Targeting FcRn for immunomodulation: Benefits, risks, and practical considerations

The neonatal fragment crystallizable (Fc) receptor (FcRn) functions as a recycling mechanism to prevent degradation and extend the half-life of IgG and albumin in the circulation. Several FcRn inhibitors selectively targeting IgG recycling are now moving rapidly toward clinical practice in neurology and hematology. These molecules accelerate the destruction of IgG, reducing pathogenic IgG and IgG immune complexes, with no anticipated effects on IgA, IgM, IgE, complement, plasma cells, B cells, or other cells of the innate or adaptive immune systems. FcRn inhibitors have potential for future use in a much wider variety of antibody-mediated autoimmune diseases. Given the imminent clinical use, potential for broader utility, and novel mechanism of action of FcRn inhibitors, here we review data from 4 main sources: (a) currently available activity, safety, and mechanism-of-action data from clinical trials of FcRn inhibitors; (b) other procedures and treatments that also remove IgG (plasma donation, plasma exchange, immunoadsorption); (c) diseases resulting in loss of IgG; and (d) primary immunodeficiencies with potential mechanistic similarities to those induced by FcRn inhibitors. These data have been evaluated to provide practical considerations for the assessment, monitoring, and reduction of any potential infection risk associated with FcRn inhibition, in addition to highlighting areas for future research.

Neuroinflammation after SCI: Current Insights and Therapeutic Potential of Intravenous Immunoglobulin

Traumatic spinal cord injury (SCI) elicits a complex cascade of cellular and molecular inflammatory events. Although certain aspects of the inflammatory response are essential to wound healing and repair, post-SCI inflammation is, on balance, thought to be detrimental to recovery by causing "bystander damage" and the spread of pathology into spared but vulnerable regions of the spinal cord. Much of the research to date has therefore focused on understanding the inflammatory drivers of secondary tissue loss after SCI, to define therapeutic targets and positively modulate this response. Numerous experimental studies have demonstrated that modulation of the inflammatory response to SCI can indeed lead to significant neuroprotection and improved recovery. However, it is now also recognized that broadscale immunosuppression is not necessarily beneficial and may even carry the risk of contributing to the development of serious adverse events. Immune modulation rather than suppression is therefore now considered a more promising approach to target harmful post-traumatic inflammation following a major neurotraumatic event such as SCI. One promising immunomodulatory agent is intravenous immunoglobulin (IVIG), a plasma product that contains mostly immunoglobulin G (IgG) from thousands of healthy donors. IVIG is currently already widely used to treat a range of autoimmune diseases, but recent studies have found that it also holds great promise for treating acute neurological conditions, including SCI. This review provides an overview of the inflammatory response to SCI, immunomodulatory approaches that are currently in clinical trials, proposed mechanisms of action for IVIG therapy, and the putative relevance of these in the context of neurotraumatic events.

Treating murine inflammatory diseases with an anti-erythrocyte antibody

Treatment of autoimmune and inflammatory diseases typically involves immune suppression. In an opposite strategy, we show that administration of the highly inflammatory erythrocyte-specific antibody Ter119 into mice remodels the monocyte cellular landscape, leading to resolution of inflammatory disease. Ter119 with intact Fc function was unexpectedly therapeutic in the K/BxN serum transfer model of arthritis. Similarly, it rapidly reversed clinical disease progression in collagen antibody-induced arthritis (CAIA) and collagen-induced arthritis and completely corrected CAIA-induced increase in monocyte Fcγ receptor II/III expression. Ter119 dose-dependently induced plasma chemokines CCL2, CCL5, CXCL9, CXCL10, and CCL11 with corresponding alterations in monocyte percentages in the blood and liver within 24 hours. Ter119 attenuated chemokine production from the synovial fluid and prevented the accumulation of inflammatory cells and complement components in the synovium. Ter119 could also accelerate the resolution of hypothermia and pulmonary edema in an acute lung injury model. We conclude that this inflammatory anti-erythrocyte antibody simultaneously triggers a highly efficient anti-inflammatory effect with broad therapeutic potential.

Intravenous Immunoglobulin G Suppresses Heat Shock Protein (HSP)-70 Expression and Enhances the Activity of HSP90 and Proteasome Inhibitors

Intravenous immunoglobulin G (IVIgG) is approved for primary immunodeficiency syndromes but may induce anti-cancer effects, and while this has been attributed to its anti-inflammatory properties, IgG against specific tumor targets may play a role. We evaluated IVIgG alone, and with a Heat shock protein (HSP)-90 or proteasome inhibitor, using multiple myeloma and mantle cell lymphoma (MCL) cells in vitro, and with the proteasome inhibitor bortezomib in vivo. IVIgG inhibited the growth of all cell lines tested, induced G₁ cell cycle arrest, and suppressed pro-tumor cytokines including Interleukin (IL)-6, IL-8, and IL-10. Genomic and proteomic studies showed that IVIgG reduced tumor cell HSP70-1 levels by suppressing the ability of extracellular HSP70-1 to stimulate endogenous HSP70-1 promoter activity, and reduced extracellular vesicle uptake. Preparations of IVIgG were found to contain high titers of anti-HSP70-1 IgG, and recombinant HSP70-1 reduced the efficacy of IVIgG to suppress HSP70-1 levels. Combining IVIgG with the HSP90 inhibitor AUY922 produced superior cell growth inhibition and correlated with HSP70-1 suppression. Also, IVIgG with bortezomib or carfilzomib was superior to each single agent, and enhanced bortezomib's activity in bortezomib-resistant myeloma cells. Moreover, IVIgG reduced transfer of extracellular vesicles (EVs) to cells, and blocked transfer of bortezomib resistance through EVs. Finally, IVIgG with bortezomib were superior to the single agents in an in vivo myeloma model. These studies support the possibility that anti-HSP70-1 IgG contained in IVIgG can inhibit myeloma and MCL growth by interfering with a novel mechanism involving uptake of exogenous HSP70-1 which then induces its own promoter.

The association and functional relevance of genetic variation in low-to-medium-affinity Fc-gamma receptors with clinical platelet transfusion refractoriness

BACKGROUND

Inadequate responses to platelet transfusions (i.e., platelet transfusion refractoriness [PLT refractoriness]) are a serious problem. Multiple factors contribute to low yields upon platelet transfusion, among which are platelet-reactive allo-antibodies. Platelet-reactive allo-antibodies occur in up to 30% of patients receiving multiple transfusions, and presumably lead to rapid destruction of the transfused platelets via receptors for IgG, the Fc-gamma receptors (FcγRs). Genetic variation in FcγRs is associated with susceptibility to immune thrombocytopenia, in which autoantibodies against platelets cause thrombocytopenia.

OBJECTIVES

We hypothesized that genetic variation in FcγRs may also influence PLT refractoriness in allo-immunized patients and could help in identifying the patients at risk.

PATIENTS/METHODS

Patients with severe PLT refractoriness for whom diagnostic testing for allo-immunization was requested in the period of 2005 to 2013 were retrospectively included. A case-control study was performed comparing patients in whom platelet-reactive antibodies were detected (n = 181) with ethnically matched healthy controls (n = 180) to determine differences in all known functional copy number variations and single nucleotide polymorphisms in FcγRs.

RESULTS AND CONCLUSIONS

None of the tested FcγR genetic variations seemed associated with the development of severe PLT refractoriness. In contrast to observations in immune thrombocytopenia, genetic variation in FcγRs does not seem to influence the chance to develop PLT refractoriness. Our results do not support determination of FcγR genetic background as a means to identify patients most at risk for PLT refractoriness.

Clinical Characteristics of 58 Children With a Pediatric Inflammatory Multisystem Syndrome Temporally Associated With SARS-CoV-2

IMPORTANCE

In communities with high rates of coronavirus disease 2019, reports have emerged of children with an unusual syndrome of fever and inflammation.

OBJECTIVES

To describe the clinical and laboratory characteristics of hospitalized children who met criteria for the pediatric inflammatory multisystem syndrome temporally associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (PIMS-TS) and compare these characteristics with other pediatric inflammatory disorders.

DESIGN, SETTING, AND PARTICIPANTS

Case series of 58 children from 8 hospitals in England admitted between March 23 and May 16, 2020, with persistent fever and laboratory evidence of inflammation meeting published definitions for PIMS-TS. The final date of follow-up was May 22, 2020. Clinical and laboratory characteristics were abstracted by medical record review, and were compared with clinical characteristics of patients with Kawasaki disease (KD) (n = 1132), KD shock syndrome (n = 45), and toxic shock syndrome (n = 37) who had been admitted to hospitals in Europe and the US from 2002 to 2019.

EXPOSURES

Signs and symptoms and laboratory and imaging findings of children who met definitional criteria for PIMS-TS from the UK, the US, and World Health Organization.

MAIN OUTCOMES AND MEASURES

Clinical, laboratory, and imaging characteristics of children meeting definitional criteria for PIMS-TS, and comparison with the characteristics of other pediatric inflammatory disorders.

RESULTS

Fifty-eight children (median age, 9 years [interquartile range {IQR}, 5.7-14]; 20 girls [34%]) were identified who met the criteria for PIMS-TS. Results from SARS-CoV-2 polymerase chain reaction tests were positive in 15 of 58 patients (26%) and SARS-CoV-2 IgG test results were positive in 40 of 46 (87%). In total, 45 of 58 patients (78%) had evidence of current or prior SARS-CoV-2 infection. All children presented with fever and nonspecific symptoms, including vomiting (26/58 [45%]), abdominal pain (31/58 [53%]), and diarrhea (30/58 [52%]). Rash was present in 30 of 58 (52%), and conjunctival injection in 26 of 58 (45%) cases. Laboratory evaluation was consistent with marked inflammation, for example, C-reactive protein (229 mg/L [IQR, 156-338], assessed in 58 of 58) and ferritin (610 μg/L [IQR, 359-1280], assessed in 53 of 58). Of the 58 children, 29 developed shock (with biochemical evidence of myocardial dysfunction) and required inotropic support and fluid resuscitation (including 23/29 [79%] who received mechanical ventilation); 13 met the American Heart Association definition of KD, and 23 had fever and inflammation without features of shock or KD. Eight patients (14%) developed coronary artery dilatation or aneurysm. Comparison of PIMS-TS with KD and with KD shock syndrome showed differences in clinical and laboratory features, including older age (median age, 9 years [IQR, 5.7-14] vs 2.7 years [IQR, 1.4-4.7] and 3.8 years [IQR, 0.2-18], respectively), and greater elevation of inflammatory markers such as C-reactive protein (median, 229 mg/L [IQR 156-338] vs 67 mg/L [IQR, 40-150 mg/L] and 193 mg/L [IQR, 83-237], respectively).

CONCLUSIONS AND RELEVANCE

In this case series of hospitalized children who met criteria for PIMS-TS, there was a wide spectrum of presenting signs and symptoms and disease severity, ranging from fever and inflammation to myocardial injury, shock, and development of coronary artery aneurysms. The comparison with patients with KD and KD shock syndrome provides insights into this syndrome, and suggests this disorder differs from other pediatric inflammatory entities.

Clinical Characteristics of 58 Children With a Pediatric Inflammatory Multisystem Syndrome Temporally Associated With SARS-CoV-2

Importance

In communities with high rates of coronavirus disease 2019, reports have emerged of children with an unusual syndrome of fever and inflammation.

Objectives

To describe the clinical and laboratory characteristics of hospitalized children who met criteria for the pediatric inflammatory multisystem syndrome temporally associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (PIMS-TS) and compare these characteristics with other pediatric inflammatory disorders.

Design, Setting, and Participants

Case series of 58 children from 8 hospitals in England admitted between March 23 and May 16, 2020, with persistent fever and laboratory evidence of inflammation meeting published definitions for PIMS-TS. The final date of follow-up was May 22, 2020. Clinical and laboratory characteristics were abstracted by medical record review, and were compared with clinical characteristics of patients with Kawasaki disease (KD) (n = 1132), KD shock syndrome (n = 45), and toxic shock syndrome (n = 37) who had been admitted to hospitals in Europe and the US from 2002 to 2019.

Exposures

Signs and symptoms and laboratory and imaging findings of children who met definitional criteria for PIMS-TS from the UK, the US, and World Health Organization.

Main Outcomes and Measures

Clinical, laboratory, and imaging characteristics of children meeting definitional criteria for PIMS-TS, and comparison with the characteristics of other pediatric inflammatory disorders.

Results

Fifty-eight children (median age, 9 years [interquartile range {IQR}, 5.7-14]; 20 girls [34%]) were identified who met the criteria for PIMS-TS. Results from SARS-CoV-2 polymerase chain reaction tests were positive in 15 of 58 patients (26%) and SARS-CoV-2 IgG test results were positive in 40 of 46 (87%). In total, 45 of 58 patients (78%) had evidence of current or prior SARS-CoV-2 infection. All children presented with fever and nonspecific symptoms, including vomiting (26/58 [45%]), abdominal pain (31/58 [53%]), and diarrhea (30/58 [52%]). Rash was present in 30 of 58 (52%), and conjunctival injection in 26 of 58 (45%) cases. Laboratory evaluation was consistent with marked inflammation, for example, C-reactive protein (229 mg/L [IQR, 156-338], assessed in 58 of 58) and ferritin (610 μg/L [IQR, 359-1280], assessed in 53 of 58). Of the 58 children, 29 developed shock (with biochemical evidence of myocardial dysfunction) and required inotropic support and fluid resuscitation (including 23/29 [79%] who received mechanical ventilation); 13 met the American Heart Association definition of KD, and 23 had fever and inflammation without features of shock or KD. Eight patients (14%) developed coronary artery dilatation or aneurysm. Comparison of PIMS-TS with KD and with KD shock syndrome showed differences in clinical and laboratory features, including older age (median age, 9 years [IQR, 5.7-14] vs 2.7 years [IQR, 1.4-4.7] and 3.8 years [IQR, 0.2-18], respectively), and greater elevation of inflammatory markers such as C-reactive protein (median, 229 mg/L [IQR 156-338] vs 67 mg/L [IQR, 40-150 mg/L] and 193 mg/L [IQR, 83-237], respectively).

Conclusions and Relevance

In this case series of hospitalized children who met criteria for PIMS-TS, there was a wide spectrum of presenting signs and symptoms and disease severity, ranging from fever and inflammation to myocardial injury, shock, and development of coronary artery aneurysms. The comparison with patients with KD and KD shock syndrome provides insights into this syndrome, and suggests this disorder differs from other pediatric inflammatory entities.

Pathophysiology and Diagnosis of Drug-Induced Immune Thrombocytopenia

Drug-induced immune thrombocytopenia (DITP) is a life-threatening clinical syndrome that is under-recognized and difficult to diagnose. Many drugs can cause immune-mediated thrombocytopenia, but the most commonly implicated are abciximab, carbamazepine, ceftriaxone, eptifibatide, heparin, ibuprofen, mirtazapine, oxaliplatin, penicillin, quinine, quinidine, rifampicin, suramin, tirofiban, trimethoprim-sulfamethoxazole, and vancomycin. Several different mechanisms have been identified in typical DITP, which is most commonly characterized by severe thrombocytopenia due to clearance and/or destruction of platelets sensitized by a drug-dependent antibody. Patients with typical DITP usually bleed when symptomatic, and biological confirmation of the diagnosis is often difficult because detection of drug-dependent antibodies (DDabs) in the patient's serum or plasma is frequently not possible. This is in contrast to heparin-induced thrombocytopenia (HIT), which is a particular DITP caused in most cases by heparin-dependent antibodies specific for platelet factor 4, which can strongly activate platelets in vitro and in vivo, explaining why affected patients usually have thrombotic complications but do not bleed. In addition, laboratory tests are readily available to diagnose HIT, unlike the methods used to detect DDabs associated with other DITP that are mostly reserved for laboratories specialized in platelet immunology.

Transient and chronic childhood immune thrombocytopenia are distinctly affected by Fc-γ receptor polymorphisms

In childhood immune thrombocytopenia (ITP), anti-platelet autoantibodies mediate platelet clearance through Fc-γ receptor (FcγR)-bearing phagocytes. In 75% to 90% of patients, the disease has a transient, self-limiting character. Here we characterized how polymorphisms of FcγR genes affect disease susceptibility, response to intravenous immunoglobulin (IVIg) treatment, and long-term recovery from childhood ITP. Genotyping of the FCGR2/3 locus was performed in 180 children with newly diagnosed ITP, 22 children with chronic ITP, and 180 healthy control children by multiplex ligation-dependent probe amplification. Children with newly diagnosed ITP were randomly assigned to a single administration of IVIg or observation, and followed for 1 year (Treatment With or Without IVIg for Kids With ITP [TIKI] trial). We defined transient ITP as a complete recovery (≥100 × 10⁹/L) 3 months after diagnosis, including both self-limiting disease/IVIg responders and chronic ITP as absence of a complete recovery at 12 months. ITP susceptibility, as well as spontaneous recovery and response to IVIg, was associated with the genetic variants FCGR2C*ORF and FCGR2A*27W and the FCGR2B promoter variant 2B.4. These variants were overrepresented in patients with transient (N = 131), but not chronic (N = 43), disease. The presence of FCGR2C*ORF predisposed to transient ITP with an odds ratio of 4.7 (95% confidence interval, 1.9-14.3). Chronic ITP was associated with a deletion of FCGR2C/FCGR3B (copy number region 1) with an odds ratio of 6.2 (95% confidence interval, 1.8-24.7). Taken together, susceptibility to transient and chronic ITP is distinctly affected by polymorphic variants of FCGR2/3 genes. Our data suggest that genotyping of the FCGR2/3 locus may be useful for prognosis and guidance of treatment decisions in newly diagnosed childhood ITP.

Impact of immune enhancement on Covid-19 polyclonal hyperimmune globulin therapy and vaccine development

The pandemic spread of a novel coronavirus - SARS coronavirus-2 (SARS-CoV-2) as a cause of acute respiratory illness, named Covid-19, is placing the healthcare systems of many countries under unprecedented stress. Global economies are also spiraling towards a recession in fear of this new life-threatening disease. Vaccines that prevent SARS-CoV-2 infection and therapeutics that reduces the risk of severe Covid-19 are thus urgently needed. A rapid method to derive antiviral treatment for Covid-19 is the use of convalescent plasma derived hyperimmune globulin. However, both hyperimmune globulin and vaccine development face a common hurdle - the risk of antibody-mediated disease enhancement. The goal of this review is to examine the body of evidence supporting the hypothesis of immune enhancement that could be pertinent to Covid-19. We also discuss how this risk could be mitigated so that both hyperimmune globulin and vaccines could be rapidly translated to overcome the current global health crisis.

A Comparative Analysis of CD32A and CD16A Polymorphisms in Relation to Autoimmune Responses in Pemphigus Diseases and Subepithelial Autoimmune Blistering Disorders

Autoimmune blistering dermatoses (ABDs) are characterized by autoantibodies to keratinocyte surface antigens and molecules within the dermal–epidermal junction causing disruption of skin integrity. The affinity of Fc receptors (FcRs) causing an autoimmune response in ABDs may vary based on single-nucleotide polymorphisms (SNPs) in FcRs determining the course of disease. This study aimed to explore the effects of CD16A and CD32A SNPs on the autoimmune response in several ABDs. In total, 61 ABDs patients were investigated. ELISA tests, direct immunofluorescence (DIF), TaqMan SNP Genotyping Assays, and statistical analyses were performed. The CA genotype (composed of allele C and A) of rs396991 in CD16A had a higher affinity for tissue-bound IgG1 in pemphigus and for C3 in subepithelial ABDs, showing statistical significance. The greatest relative risk (odds ratio) was reported for AA (rs396991 of CD16A) and CC (rs1801274 of CD32A) homozygotes. There were no statistically significant differences between certain genotypes and specific circulating autoantibodies (anti-DSG1, anti-DSG3 IgG in pemphigus; anti-BP180, anti-BP230 IgG) in subepithelial ABDs. Our findings indicated that rs396991 in CD16A may be of greater importance in ABDs development. Moreover, FcR polymorphisms appeared to have a greater impact on tissue-bound antibodies detected using DIF than circulating serum antibodies in ABDs.

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.

Current State of Precision Medicine in Primary Systemic Vasculitides

Precision medicine (PM) is an emerging data-driven health care approach that integrates phenotypic, genomic, epigenetic, and environmental factors unique to an individual. The goal of PM is to facilitate diagnosis, predict effective therapy, and avoid adverse reactions specific for each patient. The forefront of PM is in oncology; nonetheless, it is developing in other fields of medicine, including rheumatology. Recent studies on elucidating the genetic architecture of polygenic and monogenic rheumatological diseases have made PM possible by enabling physicians to customize medical treatment through the incorporation of clinical features and genetic data. For complex inflammatory disorders, the prevailing paradigm is that disease susceptibility is due to additive effects of common reduced-penetrance gene variants and environmental factors. Efforts have been made to calculate cumulative genetic risk score (GRS) and to relate specific susceptibility alleles for use of target therapies. The discovery of rare patients with single-gene high-penetrance mutations informed our understanding of pathways driving systemic inflammation. Here, we review the advances in practicing PM in patients with primary systemic vasculitides (PSVs). We summarize recent genetic studies and discuss current knowledge on the contribution of epigenetic factors and extracellular vesicles (EVs) in disease progression and treatment response. Implementation of PM in PSVs is a developing field that will require analysis of a large cohort of patients to validate data from genomics, transcriptomics, metabolomics, proteomics, and epigenomics studies for accurate disease profiling. This multi-omics approach to study disease pathogeneses should ultimately provide a powerful tool for stratification of patients to receive tailored optimal therapies and for monitoring their disease activity.

Genetic Variation in Low-To-Medium-Affinity Fcγ Receptors: Functional Consequences, Disease Associations, and Opportunities for Personalized Medicine

Fc-gamma receptors (FcγR) are the cellular receptors for Immunoglobulin G (IgG). Upon binding of complexed IgG, FcγRs can trigger various cellular immune effector functions, thereby linking the adaptive and innate immune systems. In humans, six classic FcγRs are known: one high-affinity receptor (FcγRI) and five low-to-medium-affinity FcγRs (FcγRIIA, -B and -C, FcγRIIIA and -B). In this review we describe the five genes encoding the low-to-medium -affinity FcγRs (FCGR2A, FCGR2B, FCGR2C, FCGR3A, and FCGR3B), including well-characterized functionally relevant single nucleotide polymorphisms (SNPs), haplotypes as well as copy number variants (CNVs), which occur in distinct copy number regions across the locus. The evolution of the locus is also discussed. Importantly, we recommend a consistent nomenclature of genetic variants in the FCGR2/3 locus. Next, we focus on the relevance of genetic variation in the FCGR2/3 locus in auto-immune and auto-inflammatory diseases, highlighting pathophysiological insights that are informed by genetic association studies. Finally, we illustrate how specific FcγR variants relate to variation in treatment responses and prognosis amongst autoimmune diseases, cancer and transplant immunology, suggesting novel opportunities for personalized medicine.

Efficacy and Tolerability of Intravenous Immunoglobulin and Subcutaneous Immunoglobulin in Neurologic Diseases

PURPOSE

IV immunoglobulin (Ig) therapy has been widely used for the treatment of neurologic disorders, autoimmune diseases, immunodeficiency-related diseases, blood system diseases, and cancers. In this review, we summarize the efficacy and tolerability of IVIg and SCIg therapy in neurologic diseases.

METHODS

We summarized and analyzed the efficacy and tolerability of IVIg and SCIg in neurologic diseases, by analyzing the literature pertaining to the use of IVIg and SCIg to treat nervous system diseases.

FINDINGS

In clinical neurology practice, IVIg has been shown to be useful for the treatment of new-onset or recurrent immune diseases and for long-term maintenance treatment of chronic diseases. Moreover, IVIg may have applications in the management of intractable autoimmune epilepsy, paraneoplastic syndrome, autoimmune encephalitis, and neuromyelitis optica. SCIg is emerging as an alternative to IVIg treatment. Although SCIg has a composition similar to that of IVIg, the applications of this therapy are different. Notably, the bioavailability of SCIg is lower than that of IVIg, but the homeostasis level is more stable. Current studies have shown that these 2 therapies have pharmacodynamic equivalence.

IMPLICATIONS

In this review, we explored the efficacy of IVIg in the treatment of various neurologic disorders. IVIg administration still faces many challenges. Thus, it will be necessary to standardize the use of IVIg in the clinical setting. SCIg administration is a novel and feasible treatment option for neurologic and immune-related diseases, such as chronic inflammatory demyelinating polyradiculoneuropathy and idiopathic inflammatory myopathies. As our understanding of the mechanisms of action of IVIg improve, potential next-generation biologics can being developed.

Identifying and targeting pathogenic PI3K/AKT/mTOR signaling in IL-6-blockade-refractory idiopathic multicentric Castleman disease

BACKGROUND

Idiopathic multicentric Castleman disease (iMCD) is a hematologic illness involving cytokine-induced lymphoproliferation, systemic inflammation, cytopenias, and life-threatening multi-organ dysfunction. The molecular underpinnings of interleukin-6(IL-6)-blockade refractory patients remain unknown; no targeted therapies exist. In this study, we searched for therapeutic targets in IL-6-blockade refractory iMCD patients with the thrombocytopenia, anasarca, fever/elevated C-reactive protein, reticulin myelofibrosis, renal dysfunction, organomegaly (TAFRO) clinical subtype.

METHODS

We analyzed tissues and blood samples from three IL-6-blockade refractory iMCD-TAFRO patients. Cytokine panels, quantitative serum proteomics, flow cytometry of PBMCs, and pathway analyses were employed to identify novel therapeutic targets. To confirm elevated mTOR signaling, a candidate therapeutic target from the above assays, immunohistochemistry was performed for phosphorylated S6, a read-out of mTOR activation, in three iMCD lymph node tissue samples and controls. Proteomic, immunophenotypic, and clinical response assessments were performed to quantify the effects of administration of the mTOR inhibitor, sirolimus.

RESULTS

Studies of three IL-6-blockade refractory iMCD cases revealed increased CD8+ T cell activation, VEGF-A, and PI3K/Akt/mTOR pathway activity. Administration of sirolimus significantly attenuated CD8+ T cell activation and decreased VEGF-A levels. Sirolimus induced clinical benefit responses in all three patients with durable and ongoing remissions of 66, 19, and 19 months.

CONCLUSION

This precision medicine approach identifies PI3K/Akt/mTOR signaling as the first pharmacologically-targetable pathogenic process in IL-6-blockade refractory iMCD. Prospective evaluation of sirolimus in treatment-refractory iMCD is planned (NCT03933904).

FUNDING

Castleman's Awareness & Research Effort/Castleman Disease Collaborative Network, Penn Center for Precision Medicine, University Research Foundation, Intramural NIH funding, and National Heart Lung and Blood Institute.

Extensive Ethnic Variation and Linkage Disequilibrium at the FCGR2/3 Locus: Different Genetic Associations Revealed in Kawasaki Disease

The human Fc-gamma receptors (FcγRs) link adaptive and innate immunity by binding immunoglobulin G (IgG). All human low-affinity FcγRs are encoded by the FCGR2/3 locus containing functional single nucleotide polymorphisms (SNPs) and gene copy number variants. This locus is notoriously difficult to genotype and high-throughput methods commonly used focus on only a few SNPs. We performed multiplex ligation-dependent probe amplification for all relevant genetic variations at the FCGR2/3 locus in >4,000 individuals to define linkage disequilibrium (LD) and allele frequencies in different populations. Strong LD and extensive ethnic variation in allele frequencies was found across the locus. LD was strongest for the FCGR2C-ORF haplotype (rs759550223+rs76277413), which leads to expression of FcγRIIc. In Europeans, the FCGR2C-ORF haplotype showed strong LD with, among others, rs201218628 (FCGR2A-Q27W, r² = 0.63). LD between these two variants was weaker (r² = 0.17) in Africans, whereas the FCGR2C-ORF haplotype was nearly absent in Asians (minor allele frequency <0.005%). The FCGR2C-ORF haplotype and rs1801274 (FCGR2A-H131R) were in weak LD (r² = 0.08) in Europeans. We evaluated the importance of ethnic variation and LD in Kawasaki Disease (KD), an acute vasculitis in children with increased incidence in Asians. An association of rs1801274 with KD was previously shown in ethnically diverse genome-wide association studies. Now, we show in 1,028 European KD patients that the FCGR2C-ORF haplotype, although nearly absent in Asians, was more strongly associated with susceptibility to KD than rs1801274 in Europeans. Our data illustrate the importance of interpreting findings of association studies concerning the FCGR2/3 locus with knowledge of LD and ethnic variation.

Red pulp macrophages in the human spleen are a distinct cell population with a unique expression of Fc-γ receptors

Tissue-resident macrophages in the spleen play a major role in the clearance of immunoglobulin G (IgG)-opsonized blood cells, as occurs in immune thrombocytopenia (ITP) and autoimmune hemolytic anemia (AIHA). Blood cells are phagocytosed via the Fc-γ receptors (FcγRs), but little is known about the FcγR expression on splenic red pulp macrophages in humans, with only a few previous studies that showed conflicting results. We developed a novel method to specifically isolate red pulp macrophages from 82 human spleens. Surface expression of various receptors and phagocytic capacity was analyzed by flow cytometry and immunofluorescence of tissue sections. Red pulp macrophages were distinct from splenic monocytes and blood monocyte-derived macrophages on various surface markers. Human red pulp macrophages predominantly expressed the low-affinity receptors FcγRIIa and FcγRIIIa. In contrast to blood monocyte-derived macrophages, red pulp macrophages did not express the inhibitory FcγRIIb. Red pulp macrophages expressed very low levels of the high-affinity receptor FcγRI. Messenger RNA transcript analysis confirmed this expression pattern. Unexpectedly and despite these differences in FcγR expression, phagocytosis of IgG-opsonized blood cells by red pulp macrophages was dependent on the same FcγRs as phagocytosis by blood monocyte-derived macrophages, especially in regarding the response to IV immunoglobulin. Concluding, we show the distinct nature of splenic red pulp macrophages in human subjects. Knowledge on the FcγR expression and usage of these cells is important for understanding and improving treatment strategies for autoimmune diseases such as ITP and AIHA.

Efficacy of a recombinant single-chain fragment variable region, VasSF, as a new drug for vasculitis

Background

Anti-neutrophil cytoplasmic autoantibodies (ANCA) associated vasculitis is a pauci-immune disease with the inflammation of the small blood vessels. The efficacies of antibody drugs for induction therapies of vasculitis vary among cases. Here, we developed a novel clone of a single chain Fv region (ScFv) with vasculitis-specific therapeutic potential.

Materials and methods

The clone, termed VasSF, was selected from our Escherichia coli expression library of recombinant human ScFv based on the therapeutic efficacy in an SCG/Kj mouse model of MPO-ANCA-associated vasculitis (MAAV), such as improvement of the urinary score and decreased crescent formation in glomeruli, granulomatous in lung, MPO-ANCA biomarkers, the anti-moesin antibody, and some cytokine levels.

Results

We identified vasculitis-associated apolipoprotein A-II (VAP2) as a target molecule of the clone and confirmed the independently-established VAP2 antibodies were also therapeutic in SCG/Kj mice. In MAAV, MPO-ANCA and cytokines stimulate neutrophils by facilitating heterodimer formation of VAP2 with apolipoprotein A-I in HDL.

Conclusion

VasSF would constitute a novel antibody drug for vasculitis by suppressing the heterodimer formation of the apolipoproteins.

The inflammatory function of human IgA

The prevailing concept regarding the immunological function of immunoglobulin A (IgA) is that it binds to and neutralizes pathogens to prevent infection at mucosal sites of the body. However, recently, it has become clear that in humans IgA is also able to actively contribute to the initiation of inflammation, both at mucosal and non-mucosal sites. This additional function of IgA is initiated by the formation of immune complexes, which trigger Fc alpha Receptor I (FcαRI) to synergize with various other receptors to amplify inflammatory responses. Recent findings have demonstrated that co-stimulation of FcαRI strongly affects pro-inflammatory cytokine production by various myeloid cells, including different dendritic cell subsets, macrophages, monocytes, and Kupffer cells. FcαRI-induced inflammation plays a crucial role in orchestrating human host defense against pathogens, as well as the generation of tissue-specific immunity. In addition, FcαRI-induced inflammation is suggested to be involved in the pathogenesis of various chronic inflammatory disorders, including inflammatory bowel disease, celiac disease, and rheumatoid arthritis. Combined, IgA-induced inflammation may be used to either promote inflammatory responses, e.g. in the context of cancer therapy, but may also provide new therapeutic targets to counteract chronic inflammation in the context of various chronic inflammatory disorders.

IVIg and LPS Co-stimulation Induces IL-10 Production by Human Monocytes, Which Is Compromised by an FcγRIIA Disease-Associated Gene Variant

Intravenous Immunoglobulin (IVIg) is used to treat autoimmune or inflammatory diseases, but its mechanism of action is not completely understood. We asked whether IVIg can induce interleukin-10 (IL-10) and reduce pro-inflammatory cytokine production in human monocytes, and whether this response is reduced in monocytes from people with an Fcγ receptor IIA (FcγRIIA) gene variant, which is associated with increased risk of inflammatory diseases and poor response to antibody-based biological therapy. IVIg increased IL-10 production and reduced pro-inflammatory cytokine production in response to bacterial lipopolysaccharide (LPS), which required FcγRI and FcγRIIB and activation of MAPKs, extracellular signal-regulated kinase 1/2 (ERK1/2), and p38. IL-10 production was lower and pro-inflammatory cytokine production was higher in monocytes from people with the FcγRIIA risk variant and the risk variant prevented IL-10 production in response to (IVIg+LPS). Finally, we show that IVIg did not induce MAPK activation in monocytes from people with the risk variant. Our results demonstrate that IVIg can skew human monocytes to an anti-inflammatory, IL-10-producing activation state, which is compromised in monocytes from people with the FcγRIIA risk variant. This research has profound implications for the use of IVIg because 25% of the population is homozygous for the FcγRIIA risk variant and its efficacy may be reduced in those individuals. In addition, this research may be useful to develop new therapeutic strategies to replace IVIg by cross-linking FcγRIs and FcγRIIBs to promote anti-inflammatory macrophage activation, independent of the FcγRIIA genotype.

A comprehensive overview of FCGR3A gene variability by full-length gene sequencing including the identification of V158F polymorphism

The FCGR3A gene encodes for the receptor important for antibody-dependent natural killer cell-mediated cytotoxicity. FCGR3A gene polymorphisms could affect the success of monoclonal antibody therapy. Although polymorphisms, such as the FcγRIIIA-V158F and -48L/R/H, have been studied extensively, an overview of other polymorphisms within this gene is lacking. To provide an overview of FCGR3A polymorphisms, we analysed the 1000 Genomes project database and found a total of 234 polymorphisms within the FCGR3A gene, of which 69%, 16%, and 15% occur in the intron, UTR, and exon regions respectively. Additionally, only 16% of all polymorphisms had a minor allele frequency (MAF) > 0.01. To facilitate (full-length) analysis of FCGR3A gene polymorphism, we developed a FCGR3A gene-specific amplification and sequencing protocol for Sanger sequencing and MinION (Nanopore Technologies). First, we used the Sanger sequencing protocol to study the presence of the V158F polymorphism in 76 individuals resulting in frequencies of 38% homozygous T/T, 7% homozygous G/G and 55% heterozygous. Next, we performed a pilot with both Sanger sequencing and MinION based sequencing of 14 DNA samples which showed a good concordance between Sanger- and MinION sequencing. Additionally, we detected 13 SNPs listed in the 1000 Genome Project, from which 11 had MAF > 0.01, and 10 SNPs were not listed in 1000 Genome Project. In summary, we demonstrated that FCGR3A gene is more polymorphic than previously described. As most novel polymorphisms are located in non-coding regions, their functional relevance needs to be studied in future functional studies.

IgG Glyco-Engineering to Improve IVIg Potency

Intravenous immunoglobulins (IVIg) are used in the treatment of different autoimmune and inflammatory diseases, such as immune thrombocytopenia and hemolytic anemia. One of the modes of action of IVIg is preventing phagocytosis of autoantibody-opsonized blood cells by saturation of the Fc-gamma receptors of macrophages in spleen and liver. IgG contains a fixed glycan, which is in most cases biantennary, at the asparagine residue at position 297 in the Fc tail. This glycan consists of a core structure of N-acetyl glucosamine (GlcNAc) and mannose groups, variably extended with core fucose, bisecting GlcNAc as well as terminal galactose and sialic acid. This structural glycan influences the binding affinity of IgG to Fc-gamma receptors. By glyco-engineering, we generated monoclonal IgG antibodies with different Fc-tail glycans and tested both their opsonizing and blocking capacity in a phagocytosis assay of IgG-opsonized erythrocytes with human monocyte-derived macrophages. In contrast to a lack of effect in opsono-phagocytosis, these IgG glycovariants differentially inhibited the uptake of opsonized erythrocytes. The level of bisecting GlcNAc and galactosylation had unexpectedly larger impact than core fucosylation, and suggest that targeted modifications different from the core fucose may well improve the immunomodulating efficacy of IVIg treatment.

Reversing Autoimmunity Combination of Rituximab and Intravenous Immunoglobulin

In this concept paper, the authors present a unique and novel protocol to treat autoimmune diseases that may have the potential to reverse autoimmunity. It uses a combination of B cell depletion therapy (BDT), specifically rituximab (RTX) and intravenous immunoglobulin (IVIg), based on a specifically designed protocol (Ahmed Protocol). Twelve infusions of RTX are given in 6–14 months. Once the CD20⁺ B cells are depleted from the peripheral blood, IVIg is given monthly until B cells repopulation occurs. Six additional cycles are given to end the protocol. During the stages of B cell depletion, repopulation and after clinical recovery, IVIg is continued. Along with clinical recovery, significant reduction and eventual disappearance of pathogenic autoantibody occurs. Administration of IVIg in the post-clinical period is a crucial part of this protocol. This combination reduces and may eventually significantly eliminates inflammation in the microenvironment and facilitates restoring immune balance. Consequently, the process of autoimmunity and the phenomenon that lead to autoimmune disease are arrested, and a sustained and prolonged disease and drug-free remission is achieved. Data from seven published studies, in which this combination protocol was used, are presented. It is known that BDT does not affect check points. IVIg has functions that mimic checkpoints. Hence, when inflammation is reduced and the microenvironment is favorable, IVIg may restore tolerance. The authors provide relevant information, molecular mechanism of action of BDT, IVIg, autoimmunity, and autoimmune diseases. The focus of the manuscript is providing an explanation, using the current literature, to demonstrate possible pathways, used by the combination of BDT and IVIg in providing sustained, long-term, drug-free remissions of autoimmune diseases, and thus reversing autoimmunity, albeit for the duration of the observation.