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.

Exploring Factors Influencing Changes in Incidence and Severity of Multisystem Inflammatory Syndrome in Children.

Multisystem inflammatory syndrome (MIS-C) is a rare condition associated with COVID-19 affecting children, characterized by severe and aberrant systemic inflammation leading to nonspecific symptoms, such as gastrointestinal, cardiac, respiratory, hematological, and neurological disorders. In the last year, we have experienced a progressive reduction in the incidence and severity of MIS-C, reflecting the worldwide trend. Thus, starting from the overall trend in the disease in different continents, we reviewed the literature, hypothesizing the potential influencing factors contributing to the reduction in cases and the severity of MIS-C, particularly the vaccination campaign, the spread of different SARS-CoV-2 variants (VOCs), and the changes in human immunological response. The decrease in the severity of MIS-C and its incidence seem to be related to a combination of different factors rather than a single cause. Maturation of an immunological memory to SARS-CoV-2 over time, the implication of mutations of key amino acids of S protein in VOCs, and the overall immune response elicited by vaccination over the loss of neutralization of vaccines to VOCs seem to play an important role in this change.

How to: Diagnose inborn errors of intrinsic and innate immunity to viral, bacterial, mycobacterial, and fungal infections.

BACKGROUND: Inborn errors of intrinsic and innate immunity constitute the focus of a growing research field that investigates the molecular mechanisms underlying susceptibility to infections previously not considered part of the spectrum of inborn errors of immunity. These so-called nonconventional inborn errors of immunity often occur as infections caused by a narrow spectrum of microorganisms in otherwise healthy subjects. OBJECTIVES: This review aimed to provide a framework for identifying and evaluating patients with viral, bacterial, mycobacterial, and fungal infection needing further assessment for inborn errors of intrinsic and innate immunity. SOURCES: A literature search was performed using PubMed, from inception until 1 May 2022. The search included the following keywords: "inborn errors of immunity"; "inborn errors of innate immunity"; "primary immune deficiency"; "primary immunodeficiency"; "infections"; "infectious susceptibility"; "virus"; "pyogenic bacteria"; "mycobacteria"; "fungi". All article types were considered. CONTENT: We review the definition of what can be considered an inborn error of immunity and how the definition changed over the last ∼25 years. We further provide criteria to rule out secondary immunodeficiencies, identify patients needing further clinical and laboratory immunological assessment, and suspect and diagnose an inborn error of intrinsic and innate immunity. These steps are proposed as part of an algorithm. IMPLICATIONS: Patients with unexplained life-threatening infections, including otherwise healthy subjects, should be systematically screened for known inborn errors of immunity. The early diagnosis can prevent recurrence of life-threatening infections in the patients and reduce the total burden of infectious diseases.

In-Depth Immunological Typization of Children with Sickle Cell Disease: A Preliminary Insight into Its Plausible Correlation with Clinical Course and Hydroxyurea Therapy.

Sickle cell disease (SCD) is a condition of functional hypo-/a-splenism in which predisposition to bacterial infections is only a facet of a wide spectrum of immune-dysregulation disorders forming the clinical expression of a peculiar immunophenotype. The objective of this study was to perform an in-depth immunophenotypical characterization of SCD pediatric patients, looking for plausible correlations between immunological biomarkers, the impact of hydroxyurea (HU) treatment and clinical course. This was an observational case−control study including 43 patients. The cohort was divided into two main groups, SCD subjects (19/43) and controls (24/43), differing in the presence/absence of an SCD diagnosis. The SCD group was split up into HU+ (12/19) and HU− (7/19) subgroups, respectively receiving or not a concomitant HU treatment. The principal outcomes measured were differences in the immunophenotyping between SCD patients and controls through chi-squared tests, t-tests, and Pearson's correlation analysis between clinical and immunological parameters. Leukocyte and neutrophil increase, T-cell depletion with prevalence of memory T-cell compartment, NK and B-naïve subset elevation with memory and CD21low B subset reduction, and IgG expansion, significantly distinguished the SCD HU− subgroup from controls, with naïve T cells, switched-memory B cells and IgG maintaining differences between the SCD HU+ group and controls (p-value of <0.05). The mean CD4+ central-memory T-cell% count was the single independent variable showing a positive correlation with vaso-occlusive crisis score in the SCD group (Pearson's R = 0.039). We report preliminary data assessing plausible clinical implications of baseline and HU-related SCD immunophenotypical alterations, which need to be validated in larger samples, but potentially affecting hypo-/a-splenism immuno-chemoprophylactic recommendations.

Inborn errors of immunity underlying a susceptibility to pyogenic infections: from innate immune system deficiency to complex phenotypes.

BACKGROUND: Pyogenic bacteria are associated with a wide range of clinical manifestations, ranging from common and relatively mild respiratory and cutaneous infections to life-threatening localized or systemic infections, such as sepsis and profound abscesses. Despite vaccination and the widespread use of effective antibiotic treatment, severe infection is still observed in a subset of affected patients. OBJECTIVES: We aim to summarize the available data regarding inborn errors of immunity that result in a high risk of severe pyogenic infections. SOURCES: Case series, as well as review and original articles on human genetic susceptibility to pyogenic infections were examined. CONTENT: We review host-associated factors resulting in inborn errors of immunity and leading to a susceptibility to pyogenic infections, including deficiency in major components of the immune system (e.g., neutrophils, complement, immunoglobulin, and spleen function) and novel monogenic disorders resulting in specific susceptibility to pyogenic infection. Specifically, innate immune system deficiency involving toll-like receptors and associated signaling typically predispose to a narrow spectrum of bacterial diseases in otherwise healthy people, making a diagnosis more difficult to suspect and confirm. More complex syndromes, such as hyper IgE syndrome, are associated with a high risk of pyogenic infections due to an impairment of the interleukin-6 or -17 signaling, demonstrating the pivotal role of these pathways in controlling bacterial infections. IMPLICATIONS: In clinical practice, awareness of such conditions is essential, especially in the pediatric setting, to avoid a potentially fatal diagnostic delay, set the most proper and prompt treatment, and ensure prevention of severe complications.

Refractory immune thrombocytopenia successfully treated with bortezomib in a child with 22q11.2 deletion syndrome, complicated by Evans syndrome and hypogammaglobulinemia.

Treatment of refractory autoimmune cytopenias (AICs) and Evans syndrome (ES) represent a great challenge in pediatric setting, where an underlying primary immunodeficiency is recurrent. Frequently, second or third line treatments are employed, with an increased risk of toxicity and infections. The advent of novel drugs is the object of research in order to modify the management of these patients.We report a case of successful use of bortezomib in a child with 22q11.2 deletion syndrome and CVID-like phenotype with a multi-refractory severe ES. Last flares were prolonged and dominated by severe and symptomatic ITP, refractory to different courses of high dose steroid and IVIG, mofetil mycophenolate, thrombopoietin receptor agonists, sirolimus, and rituximab. Persistence of AICs in subjects with depletion of CD20 + B-cells and IgG strengthens the hypothesis about the production of autoantibodies by terminally differentiated plasma-cells, not targetable from immunosuppressants and rituximab.In the attempt to enhance plasma-cells inhibition, the child was addressed to bortezomib, with a good response at 6 month follow-up without side effects. Nowadays, the use of bortezomib in ES/AICs is based only on small retrospective studies and case reports. Despite the lack of long term follow-up, our work highlights the potential role of bortezomib in the management of pediatric patients with multi-resistant AICs secondary to immune-system impairment.

Immune cytopenias as a continuum in inborn errors of immunity: An in-depth clinical and immunological exploration.

BACKGROUND: Immune thrombocytopenia (ITP), autoimmune hemolytic anemia (AIHA), and autoimmune neutropenia (AIN) are disorders characterized by immune-mediated destruction of hematopoietic cell lineages. A link between pediatric immune cytopenias and inborn errors of immunity (IEI) was established in particular in the combined and chronic forms. OBJECTIVE: Aim of this study is to provide clinical-immunological parameters to hematologists useful for a prompt identification of children with immune cytopenias deserving a deeper immunological and genetic evaluation. METHODS: We retrospectively collected 47 pediatric patients with at least one hematological disorder among which persistent/chronic ITP, AIHA, and AIN, aged 0-18 years at onset of immune cytopenias and/or immune-dysregulation. The cohort was divided into two groups (IEI+ and IEI-), based on the presence/absence of underlying IEI diagnosis. IEI+ group, formed by 19/47 individuals, included: common variable immune deficiency (CVID; 9/19), autoimmune lymphoproliferative syndrome (ALPS; 4/19), DiGeorge syndrome (1/19), and unclassified IEI (5/19). RESULTS: IEI prevalence among patients with ITP, AIHA, AIN, and Evans Syndrome was respectively of 42%, 64%, 36%, and 62%. In IEI+ group the extended immunophenotyping identified the presence of statistically significant (p < .05) specific characteristics, namely T/B lymphopenia, decrease in naїve T-cells%, switched memory B-cells%, plasmablasts%, and/or immunoglobulins, increase in effector/central memory T-cells% and CD21low B-cells%. Except for DiGeorge and three ALPS patients, only 2/9 CVID patients had a molecular diagnosis for IEI: one carrying the pathogenic variant CR2:c.826delT, the likely pathogenic variant PRF1:c.272C> and the compound heterozygous TNFRSF13B variants p.Ser144Ter (pathogenic) and p.Cys193Arg (variant of uncertain significance), the other one carrying the likely pathogenic monoallelic variant TNFRSF13B:p.Ile87Asn. CONCLUSION: The synergy between hematologists and immunologists can improve and fasten diagnosis and management of patients with immune cytopenias through a wide focused clinical/immunophenotypical characterization, which identifies children worthy of IEI-related molecular analysis, favouring a genetic IEI diagnosis and potentially unveiling new targeted-gene variants responsible for IEI phenotype.