Clinical and functional spectrum of RAC2-related immunodeficiency.

ABSTRACT: Mutations in the small Rho-family guanosine triphosphate hydrolase RAC2, critical for actin cytoskeleton remodeling and intracellular signal transduction, are associated with neonatal severe combined immunodeficiency (SCID), infantile neutrophilic disorder resembling leukocyte adhesion deficiency (LAD), and later-onset combined immune deficiency (CID). We investigated 54 patients (23 previously reported) from 37 families yielding 15 novel RAC2 missense mutations, including one present only in homozygosity. Data were collected from referring physicians and literature reports with updated clinical information. Patients were grouped by presentation: neonatal SCID (n = 5), infantile LAD-like disease (n = 5), or CID (n = 44). Disease correlated to RAC2 activity: constitutively active RAS-like mutations caused neonatal SCID, dominant-negative mutations caused LAD-like disease, whereas dominant-activating mutations caused CID. Significant T- and B-lymphopenia with low immunoglobulins were seen in most patients; myeloid abnormalities included neutropenia, altered oxidative burst, impaired neutrophil migration, and visible neutrophil macropinosomes. Among 42 patients with CID with clinical data, upper and lower respiratory infections and viral infections were common. Twenty-three distinct RAC2 mutations, including 15 novel variants, were identified. Using heterologous expression systems, we assessed downstream effector functions including superoxide production, p21-activated kinase 1 binding, AKT activation, and protein stability. Confocal microscopy showed altered actin assembly evidenced by membrane ruffling and macropinosomes. Altered protein localization and aggregation were observed. All tested RAC2 mutant proteins exhibited aberrant function; no single assay was sufficient to determine functional consequence. Most mutants produced elevated superoxide; mutations unable to support superoxide formation were associated with bacterial infections. RAC2 mutations cause a spectrum of immune dysfunction, ranging from early onset SCID to later-onset combined immunodeficiencies depending on RAC2 activity. This trial was registered at www.clinicaltrials.gov as #NCT00001355 and #NCT00001467.

Clinical updates in inborn errors of immunity: a focus on the noninfectious clinical manifestations.

PURPOSE OF REVIEW: In the last 5 years, several new inborn errors of immunity (IEI) have been described, especially in the areas of immune dysregulation and autoinflammation. As a result, the clinical presentation of IEIs has broadened. We review the heterogeneous presentation of IEIs and detail several of the recently described IEIs with a focus on the noninfectious manifestations commonly seen. RECENT FINDINGS: IEIs may present with early onset and/or multiple autoimmune manifestations, increased risk for malignancy, lymphoproliferation, severe atopy, autoinflammation and/or hyperinflammation. Because of this, patients can present to a wide array of providers ranging from primary care to various pediatric subspecialists. The International Union of Immunological Societies (IUIS) expert committee has created a phenotypic classification of IEIs in order to help clinicians narrow their evaluation based on the laboratory and clinical findings. SUMMARY: Both primary care pediatricians and pediatric subspecialists need to be aware of the common clinical features associated with IEI and recognize when to refer to allergy-immunology for further evaluation. Early diagnosis can lead to earlier treatment initiation and improve clinical outcomes for our patients.

Case report of severe refractory inflammatory dermatoses in a young female diagnosed with hereditary alpha tryptasemia.

Hereditary alpha tryptasemia (HaT), an autosomal dominant condition first described in 2014, has previously been associated with multiple dermatologic, allergic, gastrointestinal, neuropsychiatric, autonomic, and connective tissue abnormalities. We describe a pediatric patient with predominantly mixed cutaneous inflammatory manifestations and atopic manifestations resistant to treatment who was found to have HaT. HaT should be considered in individuals with refractory inflammatory dermatologic disease and signs and/or symptoms concerning for mast cell activation.

Inborn errors of immunity associated with elevated immunoglobulin E.

OBJECTIVE: To review the characteristic clinical and laboratory features of inborn errors of immunity (IEI) that are associated with elevated immunoglobulin (Ig)E levels. DATA SOURCES: Primary peer-reviewed literature. STUDY SELECTIONS: Original research articles reviewed include interventional studies, retrospective studies, case-control studies, cohort studies, and review articles related to the subject matter. RESULTS: An extensive literature review was completed to allow for comprehensive evaluation of several monogenic IEI. This review includes a description of the classic clinical features, common infections, characteristic laboratory findings, specific diagnostic methods (when applicable), and genetic basis of disease of each syndrome. A comprehensive flow diagram was created to assist them in the diagnosis and evaluation of patients with elevated IgE levels who may require evaluation for an IEI. CONCLUSION: IEI should be considered in patients with elevated IgE levels, especially if they have recurrent infections, eczematous dermatitis, malignancy, lymphoproliferation, autoimmunity, or connective tissue abnormalities.

A method for culturing Gram-negative skin microbiota.

BACKGROUND: Commensal Gram-negative (CGN) microbiota have been identified on human skin by DNA sequencing; however, methods to reliably culture viable Gram-negative skin organisms have not been previously described. RESULTS: Through the use of selective antibiotics and minimal media we developed methods to culture CGN from skin swabs. We identified several previously uncharacterized CGN at the species level by optimizing growth conditions and limiting the inhibitory effects of nutrient shock, temperature, and bacterial competition, factors that may have previously limited CGN isolation from skin cultures. CONCLUSIONS: Our protocol will permit future functional studies on the influences of CGN on skin homeostasis and disease.

Diagnosis and Management of Pediatric Hypereosinophilic Syndrome.

Hypereosinophilic syndrome (HES) is a diverse group of disorders characterized by peripheral blood eosinophilia of 1.5 × 109/L (1,500/µL) or greater with evidence of end-organ damage attributable to eosinophilia and no other cause of the end-organ damage. The HES is rare, especially in children. This review aims to provide best practices in diagnosis and treatment of HES in children, including how to differentiate between primary and secondary causes of hypereosinophilia; how to distinguish the differences in clinical presentation, treatment, and prognosis of HES in children and adults; and how to identify key steps in the evaluation and management of HES in children.

App providing psychosocial and educational supports benefits caregivers of children with newly diagnosed food allergies.

Background: Approximately 6 million children in the United States have a diagnosed food allergy, and 32% of caregivers experience significant psychological distress due to the diagnosis. Despite substantial impacts on psychosocial health and quality of life, few interventions aim to help caregivers of newly diagnosed children. There is a clear, unmet need for interventions to address caregiver distress, especially after the initial diagnosis. Objective: We developed a mobile psychosocial health intervention, the Food Allergy Symptom Self-Management with Technology (FASST) app. Primary end points were to determine the app's feasibility and caregiver satisfaction. Methods: This was a phase II, randomized controlled, implementation study (4-week duration) in caregivers (N = 30) of children ≤ 18 years of age who were newly diagnosed with a food allergy (≤90 days after the diagnosis). Caregivers (n = 20) were randomized to use the FASST app (intervention group) with access to individualized, self-help symptom relief interventions and food allergy support, and educational resources; or to use a limited app with a basic FASST interface and links to a few educational resources (control group [n = 10]). Ten participants (intervention group, n = 5; control group, n = 5) participated in semistructured interviews at week 4. Results: Both groups found the app relatively easy to use. The intervention group scores for safety preparedness during social activities increased by 24%, whereas those in the control group experienced a 1% decline. The intervention group participants increased the use of websites to find food allergy information by 17% at week 4 compared with 4% for the control group. Although the intervention group participants showed greater gains than did those in the control group in their confidence to prepare for and prevent allergic reactions, and greater declines in perceived social limitations, more participants in the control group endorsed confidence in their ability to recognize (11% versus 5%, respectively) and treat (10% versus 6%, respectively) allergic reactions. Conclusion: Analysis of our results suggests that the FASST app may provide a feasible means of delivering psychosocial and educational supports to caregivers of children recently diagnosed with a food allergy.Clinical trial NCT04512924, www.clinicaltrials.gov.

Teriparatide Therapy in a 4-Month-Old With Severe Hypoparathyroidism.

Teriparatide is a human parathyroid hormone analog approved for the treatment of osteoporosis in adult patients. Its use for hypocalcemia and hypoparathyroidism in the pediatric population is described through case reports and small case series; however, larger studies that demonstrate long-term efficacy and safety are limited. At our institution, a 4-month-old premature (gestational age: 32 weeks) infant with multiple congenital anomalies, functional athymia, and severe hypoparathyroidism and receiving calcitriol, vitamin D, and calcium carbonate supplementation was initiated on subcutaneous injection of teriparatide. During the course of treatment, her calcium carbonate, vitamin D, and calcitriol supplementation requirements substantially decreased. Teriparatide effectively increased serum ionized calcium concentrations and decreased serum phosphorus concentrations in the present case-study over a 6-month period. Teriparatide was well tolerated, and no evidence of hypercalcemia was observed throughout treatment.

Immune Dysregulation in Human ITCH Deficiency Successfully Treated with Hematopoietic Cell Transplantation.

BACKGROUND: Mutations in ITCH, which encodes an E3 ubiquitin-protein ligase, can result in systemic autoimmunity and immunodeficiency. The clinical phenotype and mechanism of disease have not been fully characterized, resulting in a paucity of therapeutic options for this potentially fatal disease. OBJECTIVE: We aimed to (1) expand the understanding about the phenotype of human ITCH deficiency (2) further characterize the associated immune dysregulation, and (3) report the first successful hematopoietic cell transplant (HCT) in a patient with ITCH deficiency. METHODS: Disease profiling was performed in a patient with multisystem immune dysregulation. Whole exome sequencing with trio analysis and functional validation of candidate disease variants were performed, including mRNA and protein expression. Analyses to further delineate the immunophenotype included quantitative evaluation of lymphoid and myeloid subsets with flow cytometry and mass cytometry. RESULTS: A patient with multisystem immune dysregulation presenting with growth failure, very-early-onset inflammatory bowel disease, arthritis, uveitis, psoriasis, and type 1 diabetes mellitus underwent whole exome sequencing, which identified novel compound heterozygous mutations in ITCH. Reduced expression of ITCH mRNA and absent ITCH protein were found. Abnormalities in both lymphoid and myeloid lineages were identified. The patient underwent HCT. He demonstrated excellent immune reconstitution and resolution of many manifestations of his systemic disease. CONCLUSIONS: Here we report ITCH deficiency with unique clinical features of colonic very-early-onset inflammatory bowel disease, arthritis, and uveitis in the setting of immune dysregulation and further characterize the underlying immune dysregulation. We demonstrate that HCT can be an effective, and potentially curative, therapy for ITCH deficiency.

Geographic Variability and Pathogen-Specific Considerations in the Diagnosis and Management of Chronic Granulomatous Disease.

Chronic granulomatous disease (CGD) is a rare but serious primary immunodeficiency with varying prevalence and rates of X-linked and autosomal recessive disease worldwide. Functional defects in the phagocyte nicotinamide adenine dinucleotide phosphate oxidase complex predispose patients to a relatively narrow spectrum of bacterial and fungal infections that are sometimes fastidious and often difficult to identify. When evaluating and treating patients with CGD, it is important to consider their native country of birth, climate, and living situation, which may predispose them to types of infections that are atypical to your routine practice. In addition to recurrent and often severe infections, patients with CGD and X-linked female carriers are also susceptible to developing many non-infectious complications including tissue granuloma formation and autoimmunity. The DHR-123 oxidation assay is the gold standard for making the diagnosis and it along with genetic testing can help predict the severity and prognosis in patients with CGD. Disease management focuses on prophylaxis with antibacterial, antifungal, and immunomodulatory medications, prompt identification and treatment of acute infections, and prevention of secondary granulomatous complications. While hematopoietic stem-cell transplantation is the only widely available curative treatment for patients with CGD, recent advances in gene therapy may provide a safer, more direct alternative.

First-in-human topical microbiome transplantation with Roseomonas mucosa for atopic dermatitis.

The underlying pathology of atopic dermatitis (AD) includes impaired skin barrier function, susceptibility to Staphylococcus aureus skin infection, immune dysregulation, and cutaneous dysbiosis. Our recent investigation into the potential role of Gram-negative skin bacteria in AD revealed that isolates of one particular commensal, Roseomonas mucosa, collected from healthy volunteers (HVs) improved outcomes in mouse and cell culture models of AD. In contrast, isolates of R. mucosa from patients with AD worsened outcomes in these models. These preclinical results suggested that interventions targeting the microbiome could provide therapeutic benefit for patients with AD. As a first test of this hypothesis in humans, 10 adult and 5 pediatric patients were enrolled in an open-label phase I/II safety and activity trial (the Beginning Assessment of Cutaneous Treatment Efficacy for Roseomonas in Atopic Dermatitis trial; BACTERiAD I/II). Treatment with R. mucosa was associated with significant decreases in measures of disease severity, topical steroid requirement, and S. aureus burden. There were no adverse events or treatment complications. We additionally evaluated differentiating bacterial metabolites and topical exposures that may contribute to the skin dysbiosis associated with AD and/or influence future microbiome-based treatments. These early results support continued evaluation of R. mucosa therapy with a placebo-controlled trial.

TNF overproduction impairs epithelial staphylococcal response in hyper IgE syndrome.

Autosomal dominant hyper IgE syndrome (AD-HIES), or Job's syndrome, is a primary immune deficiency caused by dominant-negative mutations in STAT3. Recurrent Staphylococcus aureus skin abscesses are a defining feature of this syndrome. A widely held hypothesis that defects in peripheral Th17 differentiation confer this susceptibility has never been directly evaluated. To assess the cutaneous immune response in AD-HIES, we induced suction blisters in healthy volunteers (HVs) and patients with AD-HIES and then challenged the wound with lethally irradiated bacteria. We show that cutaneous production of IL-17A and IL-17F was normal in patients with AD-HIES. Overproduction of TNF-α differentiated the responses in AD-HIES from HVs. This was associated with reduced IL-10 family signaling in blister-infiltrating cells and defective epithelial cell function. Mouse models of AD-HIES recapitulated these aberrant epithelial responses to S. aureus and involved defective epithelial-to-mesenchymal transition (EMT) rather than a failure of bacterial killing. Defective responses in mouse models of AD-HIES and primary keratinocyte cultures from patients with AD-HIES could be reversed by TNF-α blockade and by drugs with reported modulatory effects on EMT. Our results identify these as potential therapeutic approaches in patients with AD-HIES suffering S. aureus infections.

Molecular Typing of Staphylococcus aureus Isolated from Patients with Autosomal Dominant Hyper IgE Syndrome.

Autosomal dominant hyper IgE syndrome (AD-HIES) is a primary immunodeficiency caused by a loss-of-function mutation in the Signal Transducer and Activator of Transcription 3 (STAT3). This immune disorder is clinically characterized by increased susceptibility to cutaneous and sinopulmonary infections, in particular with Candida and Staphylococcus aureus. It has recently been recognized that the skin microbiome of patients with AD-HIES is altered with an overrepresentation of certain Gram-negative bacteria and Gram-positive staphylococci. However, these alterations have not been characterized at the species- and strain-level. Since S. aureus infections are influenced by strain-specific expression of virulence factors, information on colonizing strain characteristics may provide insights into host-pathogen interactions and help guide management strategies for treatment and prophylaxis. The aim of this study was to determine whether the immunodeficiency of AD-HIES selects for unique strains of colonizing S. aureus. Using multi-locus sequence typing (MLST), protein A (spa) typing, and PCR-based detection of toxin genes, we performed a detailed analysis of the S. aureus isolates (n = 13) found on the skin of twenty-one patients with AD-HIES. We found a low diversity of sequence types, and an abundance of strains that expressed methicillin resistance, Panton-Valentine leukocidin (PVL), and staphylococcal enterotoxins K and Q (SEK, SEQ). Our results indicate that patients with AD-HIES may often carry antibiotic-resistant strains that harbor key virulence factors.

Hypereosinophilia in Children and Adults: A Retrospective Comparison.

BACKGROUND: The differential diagnosis of hypereosinophilia is broad and includes asthma, atopic disease, drug hypersensitivity, parasitic infection, connective tissue disorders, malignancy, and rare hypereosinophilic disorders. Hypereosinophilia in children has not been well characterized to date. OBJECTIVE: The objective of this study was to identify the common causes of marked eosinophilia in children and to characterize and compare the clinical symptoms at presentation, laboratory findings, final diagnosis, and therapeutic responses between children and adults with hypereosinophilic syndromes. METHODS: A retrospective analysis of consecutive subjects evaluated for unexplained eosinophilia ≥ 1.5 × 10(9)/L was conducted. All subjects underwent standardized clinical and laboratory evaluations with yearly follow-up. Clinical and laboratory parameters, final diagnoses, treatment responses, and outcomes were assessed. Medians and proportions were compared using Mann-Whitney U and Fisher Exact tests, respectively. RESULTS: Of the 291 subjects evaluated, 37 (13%) were children and 254 were adults (87%). Whereas the frequencies of clinical hypereosinophilic syndrome (HES) variants were similar between children and adults, primary immunodeficiency was a more common secondary cause of HES in children (5% vs 0.4% in adults). Excluding subjects with treatable secondary causes, the median peak absolute eosinophil count was increased in pediatric subjects (9376 vs 5543/µL; P = .002), and children had more gastrointestinal complaints (62% vs 34%; P = .003) and less pulmonary involvement (34% vs 59%; P = .01) than adults. Despite these differences, corticosteroid responsiveness and overall prognosis were similar between the 2 groups. CONCLUSIONS: Although children with HES often present with higher peak eosinophil counts than adults, the differential diagnosis, clinical characteristics, and prognosis of HES are similar in the 2 groups.

Transplantation of human skin microbiota in models of atopic dermatitis.

Atopic dermatitis (AD) is characterized by reduced barrier function, reduced innate immune activation, and susceptibility to Staphylococcus aureus. Host susceptibility factors are suggested by monogenic disorders associated with AD-like phenotypes and can be medically modulated. S. aureus contributes to AD pathogenesis and can be mitigated by antibiotics and bleach baths. Recent work has revealed that the skin microbiome differs significantly between healthy controls and patients with AD, including decreased Gram-negative bacteria in AD. However, little is known about the potential therapeutic benefit of microbiome modulation. To evaluate whether parameters of AD pathogenesis are altered after exposure to different culturable Gram-negative bacteria (CGN) collected from human skin, CGN were collected from healthy controls and patients with AD. Then, effects on cellular and culture-based models of immune, epithelial, and bacterial function were evaluated. Representative strains were evaluated in the MC903 mouse model of AD. We found that CGN taken from healthy volunteers but not from patients with AD were associated with enhanced barrier function, innate immunity activation, and control of S. aureus. Treatment with CGN from healthy controls improved outcomes in a mouse model of AD. These findings suggest that a live-biotherapeutic approach may hold promise for treatment of patients with AD.

Extrapulmonary Aspergillus infection in patients with CARD9 deficiency.

Invasive pulmonary aspergillosis is a life-threatening mycosis that only affects patients with immunosuppression, chemotherapy-induced neutropenia, transplantation, or congenital immunodeficiency. We studied the clinical, genetic, histological, and immunological features of 2 unrelated patients without known immunodeficiency who developed extrapulmonary invasive aspergillosis at the ages of 8 and 18. One patient died at age 12 with progressive intra-abdominal aspergillosis. The other patient had presented with intra-abdominal candidiasis at age 9, and developed central nervous system aspergillosis at age 18 and intra-abdominal aspergillosis at age 25. Neither patient developed Aspergillus infection of the lungs. One patient had homozygous M1I CARD9 (caspase recruitment domain family member 9) mutation, while the other had homozygous Q295X CARD9 mutation; both patients lacked CARD9 protein expression. The patients had normal monocyte and Th17 cell numbers in peripheral blood, but their mononuclear cells exhibited impaired production of proinflammatory cytokines upon fungus-specific stimulation. Neutrophil phagocytosis, killing, and oxidative burst against Aspergillus fumigatus were intact, but neither patient accumulated neutrophils in infected tissue despite normal neutrophil numbers in peripheral blood. The neutrophil tissue accumulation defect was not caused by defective neutrophil-intrinsic chemotaxis, indicating that production of neutrophil chemoattractants in extrapulmonary tissue is impaired in CARD9 deficiency. Taken together, our results show that CARD9 deficiency is the first known inherited or acquired condition that predisposes to extrapulmonary Aspergillus infection with sparing of the lungs, associated with impaired neutrophil recruitment to the site of infection.

Anaphylaxis and urticaria.

Anaphylaxis and urticaria are common presenting allergic complaints. Affecting up to 2% of the population, anaphylaxis is a serious, life-threatening allergic reaction. Although not life-threatening, urticaria is a rash of transient, erythematous, pruritic wheals that can be bothersome and affects up to 25% of the population. All cases of anaphylaxis warrant thorough clinical evaluation by the allergist-immunologist, although most cases of urticaria are self-limited and do not require specialist referral. This article offers an overview of our current knowledge on the epidemiology, pathogenesis, triggers, diagnosis, and treatment of anaphylaxis and urticaria.