Inborn Errors of the Immune System Associated With Atopy

Atopic disorders, including atopic dermatitis, food and environmental allergies, and asthma, are increasingly prevalent diseases. Atopic disorders are often associated with eosinophilia, driven by T helper type 2 (Th2) immune responses, and triggered by disrupted barrier function leading to abnormal immune priming in a susceptible host. Immune deficiencies, in contrast, occur with a significantly lower incidence, but are associated with greater morbidity and mortality. A subset of atopic disorders with eosinophilia and elevated IgE are associated with monogenic inborn errors of immunity (IEI). In this review, we discuss current knowledge of IEI that are associated with atopy and the lessons these immunologic disorders provide regarding the fundamental mechanisms that regulate type 2 immunity in humans. We also discuss further mechanistic insights provided by animal models.

Immune dysregulation and multisystem inflammatory syndrome in children (MIS-C) in individuals with haploinsufficiency of SOCS1

Background

We studied 2 unrelated patients with immune thrombocytopenia and autoimmune hemolytic anemia in the setting of acute infections. One patient developed multisystem inflammatory syndrome in children in the setting of a severe acute respiratory syndrome coronavirus 2 infection.

Objectives

We sought to identify the mechanisms underlying the development of infection-driven autoimmune cytopenias.

Methods

Whole-exome sequencing was performed on both patients, and the impact of the identified variants was validated by functional assays using the patients’ PBMCs.

Results

Each patient was found to have a unique heterozygous truncation variant in suppressor of cytokine signaling 1 (SOCS1). SOCS1 is an essential negative regulator of type I and type II IFN signaling. The patients’ PBMCs showed increased levels of signal transducer and activator of transcription 1 phosphorylation and a transcriptional signature characterized by increased expression of type I and type II IFN-stimulated genes and proapoptotic genes. The enhanced IFN signature exhibited by the patients’ unstimulated PBMCs parallels the hyperinflammatory state associated with multisystem inflammatory syndrome in children, suggesting the contributions of SOCS1 in regulating the inflammatory response characteristic of multisystem inflammatory syndrome in children.

Conclusions

Heterozygous loss-of-function SOCS1 mutations are associated with enhanced IFN signaling and increased immune cell activation, thereby predisposing to infection-associated autoimmune cytopenias.

Immunoglobulins in the treatment of COVID-19 infection: Proceed with caution!

The COVID-19 pandemic is one of the greatest infectious challenges in recent history. Presently, few treatment options exist and the availability of effective vaccines is at least one year away. There is an urgent need to find currently available, effective therapies in the treatment of patients with COVID-19 infection. In this review, we compare and contrast the use of intravenous immunoglobulin and hyperimmune globulin in the treatment of COVID-19 infection.

RIG-I and TLR4 responses and adverse outcomes in pediatric influenza-related critical illness

BACKGROUND

Decreased TNF-α production in whole blood after ex vivo LPS stimulation indicates suppression of the Toll-like receptor (TLR)4 pathway. This is associated with increased mortality in pediatric influenza critical illness. Whether antiviral immune signaling pathways are also suppressed in these patients is unclear.

OBJECTIVES

We sought to evaluate suppression of the TLR4 and the antiviral retinoic acid-inducible gene-I (RIG-I) pathways with clinical outcomes in children with severe influenza infection.

METHODS

In this 24-center, prospective, observational cohort study of children with confirmed influenza infection, blood was collected within 72 hours of intensive care unit admission. Ex vivo whole blood stimulations were performed with matched controls using the viral ligand polyinosinic-polycytidylic acid-low-molecular-weight/LyoVec and LPS to evaluate IFN-α and TNF-α production capacities (RIG-I and TLR4 pathways, respectively).

RESULTS

Suppression of either IFN-α or TNF-α production capacity was associated with longer duration of mechanical ventilation and hospitalization, and increased organ dysfunction. Children with suppression of both RIG-I and TLR4 pathways (n = 33 of 103 [32%]) were more likely to have prolonged (≥7 days) multiple-organ dysfunction syndrome (30.3% vs 8.6%; P = .004) or prolonged hypoxemic respiratory failure (39.4% vs 11.4%; P = .001) compared with those with single- or no pathway suppression.

CONCLUSIONS

Suppression of both RIG-I and TLR4 signaling pathways, essential for respective antiviral and antibacterial responses, is common in previously immunocompetent children with influenza-related critical illness and is associated with bacterial coinfection and adverse outcomes. Prospective testing of both pathways may aid in risk-stratification and in immune monitoring.

Defective TLR9-driven STAT3 activation in B cells of patients with CVID

B cell activation by Toll-like receptor 9 (TLR9) ligands is dependent on STAT3 and is important for optimal antibody responses to microbial antigens. B cells from patients with common variable immune deficiency (CVID) have impaired proliferation and differentiation in response to the TLR9 ligand CpG, despite normal levels of TLR9 expression. We demonstrate that CpG-driven STAT3 phosphorylation, but not activation of NFκB and p38, is selectively impaired in B cells from CVID patients. These results suggest that defective STAT3 activation contributes to the defective TLR9 and antibody response of B cells in CVID.

Hematopoietic stem cell transplantation outcomes for 11 patients with dedicator of cytokinesis 8 deficiency

BACKGROUND

Dedicator of cytokinesis 8 (DOCK8) deficiency can be cured by allogeneic hematopoietic stem cell transplantation (HSCT). Reports of outcomes are still limited.

OBJECTIVE

We sought to analyze the results of HSCT in patients with DOCK8 deficiency and report whether approaches resulting in mixed chimerism result in clinically relevant immune reconstitution.

METHODS

We performed a retrospective chart review of 11 patients with DOCK8 deficiency and measured DOCK8 expression and cytokine production.

RESULTS

Of 11 patients, 7 received HSCT from related and 4 from unrelated donors; 9 patients received busulfan-based conditioning regimens. Survival was excellent (10 [91%] of 11 patients alive), including a patient who had undergone liver transplantation. Patients showed significant improvements in the frequency and severity of infections. Although eczema resolved in all, food allergies and high IgE levels persisted in some patients. Lymphopenia, eosinophilia, low numbers of naive CD8(+) T cells and switched memory B cells, and TH1/TH2 cytokine imbalance improved in most patients. Although the 8 matched related or unrelated donor recipients had full donor chimerism, all 3 recipients of mismatched unrelated donor HSCT had high levels of donor T-cell chimerism and low B-cell and myeloid cell chimerism (0% to 46%). Almost all switched memory B cells were of donor origin. All patients, including those with mixed chimerism, mounted robust antibody responses to vaccination.

CONCLUSION

Allogeneic HSCT ameliorated the infectious and atopic symptoms of patients with DOCK8 deficiency. In patients with mixed chimerism, selective advantage for donor-derived T cells and switched memory B cells promoted restoration of cellular and humoral immunity and protection against opportunistic infection.

Intraoperative anaphylaxis to gelatin in topical hemostatic agents during anterior spinal fusion: a case report

BACKGROUND CONTEXT

The use of topical hemostatic agents is widespread and has been shown to reduce bleeding during a wide variety of surgical procedures. Nonetheless, as biologically active agents, there is potential for allergic reactions to these products.

PURPOSE

This is a report of intraoperative anaphylaxis to gelatin associated with the use of two topical hemostatic agents.

STUDY DESIGN

Case report. There is no outside funding or potential conflict of interest.

PATIENT SAMPLE

A patient with anaphylaxis during anterior spinal fusion.

OUTCOME MEASURES

Laboratory assays for tryptase, gelatin-specific immunoglobulin E (IgE), and total IgE.

METHODS

A 14-year-old male with myelomeningocele and scoliosis was treated with anterior spinal fusion from T12 to L3. Gelfoam sponges were applied during the preparation of the disc spaces. Approximately 1 hour later, Floseal hemostatic matrix was applied to a briskly bleeding screw hole in the L3 vertebral body, and the patient experienced an abrupt onset of hypotension and ventilatory difficulty. Epinephrine, dexamethasone, and blood products were administered for hemodynamic support while the surgical site was closed. Removal of the drapes revealed a widespread erythematous rash, and the patient was then transferred to the intensive care unit. When stable 3 days later, he returned to the operating room for completion of the spinal fusion.

RESULTS

Postoperative laboratory assays were sent that revealed elevated levels of tryptase, total IgE, porcine, and bovine gelatin-specific IgE. The patient was counseled to avoid gelatin-containing products. At 6-month follow-up, his instrumented spine was radiographically fused and he reported no further allergic issues.

CONCLUSIONS

Anaphylaxis may occur because of animal gelatin components of topical hemostatic agents. Previous reports have focused on the thrombin components. Care should be taken in the administration of these products, particularly in the atopic individual.

DOCK8 functions as an adaptor that links TLR-MyD88 signaling to B cell activation

DOCK8 and MyD88 have been implicated in serologic memory. Here we report antibody responses were impaired and CD27⁺ memory B cells were severely reduced in DOCK8-deficient patients. Toll-like receptor 9 (TLR9)- but not CD40-driven B cell proliferation and immunoglobulin production were severely reduced in DOCK8-deficient B cells. In contrast, TLR9-driven expression of AICDA, CD23 and CD86, and activation of NF-κB, p38 and Rac1 were intact. DOCK8 associated constitutively with MyD88 and the tyrosine kinase Pyk2 in normal B cells. Following TLR9 ligation, DOCK8 became tyrosine phosphorylated by Pyk2, bound the Src family kinase Lyn and linked TLR9 to a Src-Syk-STAT3 cascade essential for TLR9-driven B cell proliferation and differentiation. Thus, DOCK8 functions as an adaptor in a TLR9-MyD88 signaling pathway in B cells.

TH17 deficiency in human disease

The differentiation of naive T cells into distinct subsets of effector T cells is critical for effective immunity against a wide variety of infectious agents in the environment. Activation of innate immune responses by Candida species through pattern-recognition receptors directs the subsequent development of naive T cells into T(H)17 cells, which are essential for effective mucosal immunity against fungi. Thorough analyses of cohorts of patients with unusual susceptibility to chronic mucocutaneous candidiasis resulting from T(H)17 deficiency have confirmed the role of T(H)17 cells and T(H)17 cytokines in human host defense against Candida species and have provided valuable insights into the complex process of T(H)17 cell development.

Impaired T-cell receptor activation in IL-1 receptor-associated kinase-4-deficient patients

BACKGROUND

IL-1 receptor-associated kinase 4 (IRAK-4) is an effector of the Toll-like receptor and IL-1 receptor pathways that plays a critical role in innate immune responses. The role of IRAK-4 in adaptive immune functions in human subjects is incompletely understood.

OBJECTIVE

We sought to evaluate T-cell function in IRAK-4 deficient patients.

METHODS

We compared upregulation of CD25 and CD69 on T cells and production of IL-2, IL-6, and IFN-gamma after stimulation of PBMCs from 4 IRAK-4-deficient patients and healthy control subjects with anti-CD3 and anti-CD28.

RESULTS

Upregulation of CD25 and CD69 on T cells and production of IL-6 and IFN-gamma, but not IL-2, was significantly reduced in IRAK-4-deficient patients.

CONCLUSIONS

IRAK-4-deficient patients have defects in T-cell activation.

Immune deficiency caused by impaired expression of nuclear factor-kappaB essential modifier (NEMO) because of a mutation in the 5' untranslated region of the NEMO gene

BACKGROUND

Nuclear factor-kappaB (NF-kappaB) is a key transcription factor that regulates both innate and adaptive immunity as well as ectodermal development. Mutations in the coding region of the IkappaB kinase gamma/NF-kappaB essential modifier (NEMO) gene cause X-linked ectodermal dysplasia with immunodeficiency.

OBJECTIVE

To determine the genetic cause of recurrent sinopulmonary infections and dysgammaglobulinemia in a patient with a normal NEMO coding sequence and his affected brother.

METHODS

TNF-alpha and IFN-alpha production in response to Toll-like receptor (TLR) stimulation was analyzed by ELISA, NEMO mRNA levels were measured by quantitative PCR, and NEMO protein expression was measured by Western blotting. NF-kappaB activation was assessed by nuclear translocation of p65 and luciferase reporter gene assays.

RESULTS

TLR-induced TNF-alpha and IFN-alpha production by PBMCs was impaired in the patient and his brother. Sequencing of the patient's NEMO gene revealed a novel mutation in the 5' untranslated region, which was also present in the brother, resulting in abnormally spliced transcripts and a 4-fold reduction in mRNA levels. NEMO protein levels in EBV transformed B cells and fibroblasts from the index patient were 8-fold lower than normal controls. NF-kappaB p65 nuclear translocation in the patient's EBV B cells after TLR7 ligation was defective. NF-kappaB-dependent luciferase gene expression in IL-1-stimulated fibroblasts from the patient was impaired.

CONCLUSION

This is the first description of immune deficiency resulting from low expression of a normal NEMO protein.

Heterozygous N-terminal deletion of IkappaBalpha results in functional nuclear factor kappaB haploinsufficiency, ectodermal dysplasia, and immune deficiency

BACKGROUND

Nuclear factor kappaB (NF-kappaB) is a master transcriptional regulator critical for ectodermal development and normal innate and adaptive immune function. Mutations in the IkappaB kinase gamma/NF-kappaB essential modifier have been described in male subjects with the syndrome of X-linked ectodermal dysplasia with immune deficiency that results from impaired activation of NF-kappaB.

OBJECTIVES

We sought to determine the genetic cause of ectodermal dysplasia with immune deficiency in a female patient.

METHODS

Toll-like receptor-induced production of the NF-kappaB-dependent cytokines TNF-alpha and IFN-alpha was examined by means of ELISA, the patient's IkappaBalpha gene was sequenced, and NF-kappaB activation was evaluated by means of electrophoretic mobility shift assay and NF-kappaB-luciferase assays in transfectants.

RESULTS

Toll-like receptor function was impaired in the patient. Sequencing of the patient's IkappaBalpha gene revealed a novel heterozygous mutation at amino acid 11 (W11X). The mutant IkappaBalphaW11X protein did not undergo ligand-induced phosphorylation or degradation and retained NF-kappaB in the cytoplasm. This led to roughly a 50% decrease in NF-kappaB DNA-binding activity, leading to functional haploinsufficiency of NF-kappaB activation. Unlike the only other reported IkappaBalpha mutant associated with ectodermal dysplasia associated with immune deficiency (ED-ID), S32I, IkappaBalphaW11X exerted no dominant-negative effect.

CONCLUSIONS

Functional NF-kappaB haploinsufficiency was associated with ED-ID, and this strongly suggests that normal ectodermal development and immune function are stringently dependent on NF-kappaB in that they might require more than half of normal NF-kappaB activity.

CLINICAL IMPLICATIONS

Although ED-ID is well described in male subjects, female subjects can present with a similar syndrome of ectodermal dysplasia with immune deficiency resulting from mutations in autosomal genes within the NF-kappaB pathway.

Interleukin receptor-associated kinase-4 deficiency impairs Toll-like receptor-dependent innate antiviral immune responses

BACKGROUND

Engagement of all known Toll-like receptors (TLRs) causes the production of inflammatory cytokines, including TNF-alpha, whereas in humans, engagement of TLRs 3, 7, 8, and 9 also induces type I IFNs. IRAK-4 is a critical effector in signaling by TLRs and the IL-1 receptor, which share homology in their intracellular domain and recruit IRAK-4 via the adaptor myeloid differentiation factor 88 (MyD88). Patients with IRAK-4 deficiency are susceptible to invasive bacterial infections but have so far not been reported to be susceptible to viral infection. Blood cells from these patients are impaired in their ability to make TNF-alpha in response to activation by TLRs. A recent report has described concomitant impairment of type I IFN production after activation of TLRs 7, 8, and 9, but not TLR3.

OBJECTIVES

We sought to evaluate the role of IRAK-4 in TLR-induced production of the type I IFN, IFN-alpha, in humans.

METHODS

We examined TLR-induced production of TNF-alpha and IFN-alpha in PBMCs from an IRAK-4-deficient patient, his heterozygous carrier parents, and normal controls.

RESULTS

TNF-alpha production in response to TLR agonists was severely impaired in the patient. IFN-alpha production induced by TLR7, TLR8, and TLR9, as well as TLR3 agonists, was low or absent.

CONCLUSIONS

IRAK-4 plays an important role in the production of type I IFN, as well as TNF-alpha, induced by all TLRs, including TLR3.

CLINICAL IMPLICATIONS

IRAK-4 may play a broader role in human innate antiviral immunity than previously appreciated.

Lessons learned from molecular defects in nuclear factor kappaB dependent signaling

Nuclear factor (NF) kappaB is a ubiquitously expressed transcription factor that plays critical roles in normal development and inflammation. Characterization of naturally occurring defects in signaling pathways leading to activation of NFkappaB, complemented by mouse knockout models, has demonstrated the vital role of NFkappaB in normal host defense.

Alleged effect of bile constituents on gentamicin assays

It has been claimed that gentamicin assays on the serum of jaundiced patients give falsely low levels and suggested that the antibiotic in such sera is bound to bile acids and thus is partly inactivated. No evidence of such inactivation has been obtained (i) in the serum of jaundiced patients treated with gentamicin, (ii) in sera with high bilirubin contents to which gentamicin was added, or (iii) when bile or bile acids were added with gentamicin to normal serum.

A cell surface receptor complex for fibrillar beta-amyloid mediates microglial activation

Senile plaques found in the Alzheimer's disease brain are foci of local inflammatory reactions mediated by plaque-associated microglia. The interaction of microglia with compacted deposits of beta-amyloid (Abeta) fibrils results in the stimulation of intracellular Tyr kinase-based signaling cascades and cellular activation, leading to the secretion of proinflammatory molecules. This study identifies a cell surface receptor complex that mediates the binding of microglia to Abeta fibrils and the subsequent activation of intracellular signaling pathways leading to a proinflammatory response. The receptor complex includes the B-class scavenger receptor CD36, the integrin-associated protein/CD47, and the alpha(6)beta(1)-integrin. Antagonists of scavenger receptors, CD36, CD47, and alpha(6)beta(1) inhibited the adhesion of THP-1 monocytes to Abeta fibrils. In addition, peptide competitors of Abeta fibril interactions with CD36, scavenger receptors, CD47, and the alpha(6)beta(1)-integrin inhibited Abeta stimulation of Tyr kinase-based signaling cascades in both THP-1 monocytes and murine microglia as well as interleukin 1beta production. A scavenger receptor antagonist and antibodies specific for CD36 and the beta(1)-integrin subunit also inhibited the Abeta-stimulated generation of reactive oxygen species. Importantly, the principal components of this receptor complex are shared with those for other fibrillar proteins and thus represent general elements through which myeloid lineage cells recognize complex fibrillar proteins. Identification of the cell surface molecules that interact with Abeta fibrils and mediate their activation of intracellular signaling cascades represents a potential intervention point in the treatment of Alzheimer's disease.

beta-Amyloid fibrils activate parallel mitogen-activated protein kinase pathways in microglia and THP1 monocytes

The senile plaques of Alzheimer's disease are foci of local inflammatory responses, as evidenced by the presence of acute phase proteins and oxidative damage. Fibrillar forms of beta-amyloid (Abeta), which are the primary constituents of senile plaques, have been shown to activate tyrosine kinase-dependent signal transduction cascades, resulting in inflammatory responses in microglia. However, the downstream signaling pathways mediating Abeta-induced inflammatory events are not well characterized. We report that exposure of primary rat microglia and human THP1 monocytes to fibrillar Abeta results in the tyrosine kinase-dependent activation of two parallel signal transduction cascades involving members of the mitogen-activated protein kinase (MAPK) superfamily. Abeta stimulated the rapid, transient activation of extracellular signal-regulated kinase 1 (ERK1) and ERK2 in microglia and ERK2 in THP1 monocytes. A second superfamily member, p38 MAPK, was also activated with similar kinetics. Scavenger receptor and receptor for advanced glycated end products (RAGE) ligands failed to activate ERK and p38 MAPK in the absence of significant increases in protein tyrosine phosphorylation, demonstrating that scavenger receptors and RAGE are not linked to these pathways. Importantly, the stress-activated protein kinases (SAPKs) were not significantly activated in response to Abeta. Downstream effectors of the MAPK signal transduction cascades include MAPKAP kinases, such as RSK1 and RSK2, as well as transcription factors. Exposure of microglia and THP1 monocytes to Abeta resulted in the activation of RSK1 and RSK2 and phosphorylation of cAMP response element-binding protein at Ser133, providing a mechanism for Abeta-induced changes in gene expression.

Amyloid fibrils activate tyrosine kinase-dependent signaling and superoxide production in microglia

Alzheimer's disease (AD) is a devastating neurological disorder characterized by loss of cognitive skills and progressive dementia. The pathological hallmark of AD is the presence of numerous senile plaques throughout the hippocampus and cerebral cortex associated with degenerating axons, neurofibrillary tangles, and gliosis. The core of the senile plaque primarily is composed of the 39-43 amino acid beta-amyloid peptide (Abeta), which forms fibrils of beta-pleated sheets. Although considerable genetic evidence implicates Abeta in the pathogenesis of AD, a direct causal link remains to be established. Senile plaques are foci of local inflammatory processes, as evidenced by the presence of numerous activated microglia and acute phase proteins. Abeta has been shown to elicit inflammatory responses in microglia; however, the intracellular events mediating these effects are largely unknown. We report that exposure of microglia and THP1 monocytes to fibrillar Abeta led to time- and dose-dependent increases in protein tyrosine phosphorylation of a population of proteins similar to that elicited by classical immune stimuli such as immune complexes. The tyrosine kinases Lyn, Syk, and FAK were activated on exposure of microglia and THP1 monocytes to Abeta, resulting in the tyrosine kinase-dependent generation of superoxide radicals. The present data support a role for oxidative damage in the pathogenesis of AD, provide an important mechanistic link between Abeta and the generation of reactive oxygen intermediates, and identify molecular targets for therapeutic intervention in AD.

Rapid carbohydrate utilization test for the identification of Neisseria gonorrhoeae

A rapid carbohydrate utilization test for the identification of N. gonorrhoeae was investigated, with reference to its use in a routine diagnostic laboratory. The rapid test was shown to give accurate results in agreement with those of a conventional serum-free sugar medium. Because of the shorter time taken for the confirmation of an isolate, and several other advantages, it is proposed that the rapid test is an extremely useful alternative to conventional sugar tests. Immunofluorescence was also used to identify isolates of N. gonorrhoeae and the rapid carbohydrate utilization test was found to assist in differentiating between N. gonorrhoeae and N. meningitidis when equivocal or negative immunofluorescence results were obtained.