Functional Selectivity in Cytokine Signaling Revealed Through a Pathogenic EPO Mutation.

Cytokines are classically thought to stimulate downstream signaling pathways through monotonic activation of receptors. We describe a severe anemia resulting from a homozygous mutation (R150Q) in the cytokine erythropoietin (EPO). Surprisingly, the EPO R150Q mutant shows only a mild reduction in affinity for its receptor but has altered binding kinetics. The EPO mutant is less effective at stimulating erythroid cell proliferation and differentiation, even at maximally potent concentrations. While the EPO mutant can stimulate effectors such as STAT5 to a similar extent as the wild-type ligand, there is reduced JAK2-mediated phosphorylation of select downstream targets. This impairment in downstream signaling mechanistically arises from altered receptor dimerization dynamics due to extracellular binding changes. These results demonstrate how variation in a single cytokine can lead to biased downstream signaling and can thereby cause human disease. Moreover, we have defined a distinct treatable form of anemia through mutation identification and functional studies.

Outcomes of HLA-mismatched HSCT with TCRαß/CD19 depletion or post-HSCT cyclophosphamide for inborn errors of immunity.

ABSTRACT: HLA-mismatched transplants with either in vitro depletion of CD3+ T-cell receptor (TCR)αß/CD19 (TCRαß) cells or in vivo T-cell depletion using posttransplant cyclophosphamide (PTCY) have been increasingly used for patients with inborn errors of immunity (IEIs). We performed a retrospective multicenter study via the EBMT registry on 306 children with IEIs undergoing their first transplant between 2010 and 2019 from an HLA-mismatched donor using TCRαß (n = 167) or PTCY (n = 139). The median age for hematopoietic stem cell transplantation (HSCT) was 1.2 years (range, 0.03-19.6 years). The 3-year overall survival (OS) was 78% (95% confidence interval (CI), 71-84) after TCRαß and 66% (57-74) after PTCY (P = .013). Pre-HSCT morbidity score (hazard ratio [HR], 2.27; 1.07-4.80, P = .032) and non-busulfan/treosulfan conditioning (HR, 3.12; 1.98-4.92, P < .001) were the only independent predictors of unfavorable OS. The 3-year event-free survival (EFS) was 58% (50%-66%) after TCRαß and 57% (48%-66%) after PTCY (P = .804). The cumulative incidence of severe acute graft-versus-host disease (GvHD) was higher after PTCY (15%, 9%-21%) than TCRαß (6%, 2%-9%, P = .007), with no difference in chronic GvHD (PTCY, 11%, 6%-17%; TCRαß, 7%, 3%-11%, P = .173). The 3-year GvHD-free EFS was 53% (44%-61%) after TCRαß and 41% (32%-50%) after PTCY (P = .080). PTCY had significantly higher rates of veno-occlusive disease (14.4% vs TCRαß 4.9%, P = .009), acute kidney injury (12.7% vs 4.6%, P = .032), and pulmonary complications (38.2% vs 24.1%, P = .017). Adenoviremia (18.3% vs PTCY 8.0%, P = .015), primary graft failure (10% vs 5%, P = .048), and second HSCT (17.4% vs 7.9%, P = .023) were significantly higher in TCRαß. In conclusion, this study demonstrates that both approaches are suitable options in patients with IEIs, although they are characterized by different advantages and outcomes.

Pyruvate kinase deficiency in 29 Turkish patients with two novel intronic variants.

Pyruvate kinase (PK) is a key enzyme of anaerobic glycolysis. The genetic heterogeneity of PK deficiency (PKD) is high, and over 400 unique variants have been identified. Twenty-nine patients who had been diagnosed as PKD genetically in seven distinct paediatric haematology departments were evaluated. Fifteen of 23 patients (65.2%) had low PK levels. The PK:hexokinase ratio had 100% sensitivity for PKD diagnosis, superior to PK enzyme assay. Two novel intronic variants (c.695-1G>A and c.694+43C>T) have been described. PKD should be suspected in patients with chronic non-spherocytic haemolytic anaemia, even if enzyme levels are falsely normal. Total PKLR gene sequencing is necessary for the characterization of patients with PKD and for genetic counselling.

DIAPH1-Deficiency is Associated with Major T, NK and ILC Defects in Humans.

Loss of function mutations in Diaphanous related formin 1 (DIAPH1) are associated with seizures, cortical blindness, and microcephaly syndrome (SCBMS) and are recently linked to combined immunodeficiency. However, the extent of defects in T and innate lymphoid cells (ILCs) remain unexplored. Herein, we characterized the primary T, natural killer (NK) and helper ILCs of six patients carrying two novel loss of function mutation in DIAPH1 and Jurkat cells after DIAPH1 knockdown. Mutations were identified by whole exome sequencing. T-cell immunophenotyping, proliferation, migration, cytokine signaling, survival, and NK cell cytotoxicity were studied via flow cytometry-based assays, confocal microscopy, and real-time qPCR. CD4+ T cell proteome was analyzed by mass spectrometry. p.R351* and p.R322*variants led to a significant reduction in the DIAPH1 mRNA and protein levels. DIAPH1-deficient T cells showed proliferation, activation, as well as TCR-mediated signaling defects. DIAPH1-deficient PBMCs also displayed impaired transwell migration, defective STAT5 phosphorylation in response to IL-2, IL-7 and IL-15. In vitro generation/expansion of Treg cells from naïve T cells was significantly reduced. shRNA-mediated silencing of DIAPH1 in Jurkat cells reduced DIAPH1 protein level and inhibited T cell proliferation and IL-2/STAT5 axis. Additionally, NK cells from patients had diminished cytotoxic activity, function and IL-2/STAT5 axis. Lastly, DIAPH1-deficient patients' peripheral blood contained dramatically reduced numbers of all helper ILC subsets. DIAPH1 deficiency results in major functional defects in T, NK cells and helper ILCs underlining the critical role of formin DIAPH1 in the biology of those cell subsets.

COVID-19 disease in children and adolescents following allogeneic hematopoietic stem cell transplantation: A report from the Turkish pediatric bone marrow transplantation study group.

BACKGROUND: Data on the risk factors and outcomes for pediatric patients with SARS-CoV-2 infection (COVID-19) following hematopoietic stem cell transplantation (HSCT) are limited. OBJECTIVES: The study aimed to analyze the clinical signs, risk factors, and outcomes for ICU admission and mortality in a large pediatric cohort who underwent allogeneic HSCT prior to COVID-19 infection. METHOD: In this nationwide study, we retrospectively reviewed the data of 184 pediatric HSCT recipients who had COVID-19 between March 2020 and August 2022. RESULTS: The median time from HSCT to COVID-19 infection was 209.0 days (IQR, 111.7-340.8; range, 0-3845 days). The most common clinical manifestation was fever (58.7%). While most patients (78.8%) had asymptomatic/mild disease, the disease severity was moderate in 9.2% and severe and critical in 4.4% and 7.6%, respectively. The overall mortality was 10.9% (n: 20). Deaths were attributable to COVID-19 in nine (4.9%) patients. Multivariate analysis revealed that lower respiratory tract disease (LRTD) (OR, 23.20, p: .001) and lymphopenia at diagnosis (OR, 5.21, p: .006) were risk factors for ICU admission and that HSCT from a mismatched donor (OR, 54.04, p: .028), multisystem inflammatory syndrome in children (MIS-C) (OR, 31.07, p: .003), and LRTD (OR, 10.11, p: .035) were associated with a higher risk for COVID-19-related mortality. CONCLUSION: While COVID-19 is mostly asymptomatic or mild in pediatric transplant recipients, it can cause ICU admission in those with LRTD or lymphopenia at diagnosis and may be more fatal in those who are transplanted from a mismatched donor and those who develop MIS-C or LRTD.

Immunodeficiency associated with a novel functionally defective variant of SLC19A1 benefits from folinic acid treatment.

Insufficient dietary folate intake, hereditary malabsorption, or defects in folate transport may lead to combined immunodeficiency (CID). Although loss of function mutations in the major intestinal folate transporter PCFT/SLC46A1 was shown to be associated with CID, the evidence for pathogenic variants of RFC/SLC19A1 resulting in immunodeficiency was lacking. We report two cousins carrying a homozygous pathogenic variant c.1042 G > A, resulting in p.G348R substitution who showed symptoms of immunodeficiency associated with defects of folate transport. SLC19A1 expression by peripheral blood mononuclear cells (PBMC) was quantified by real-time qPCR and immunostaining. T cell proliferation, methotrexate resistance, NK cell cytotoxicity, Treg cells and cytokine production by T cells were examined by flow cytometric assays. Patients were treated with and benefited from folinic acid. Studies revealed normal NK cell cytotoxicity, Treg cell counts, and naive-memory T cell percentages. Although SLC19A1 mRNA and protein expression were unaltered, remarkably, mitogen induced-T cell proliferation was significantly reduced at suboptimal folic acid and supraoptimal folinic acid concentrations. In addition, patients' PBMCs were resistant to methotrexate-induced apoptosis supporting a functionally defective SLC19A1. This study presents the second pathogenic SLC19A1 variant in the literature, providing the first experimental evidence that functionally defective variants of SLC19A1 may present with symptoms of immunodeficiency.

Defective Treg generation and increased type 3 immune response in leukocyte adhesion deficiency 1.

In 15 Turkish LAD-1 patients and controls, we assessed the impact of pathogenic ITGB2 mutations on Th17/Treg differentiation and functions, and innate lymphoid cell (ILC) subsets. The percentage of peripheral blood Treg cells, in vitro-generated induced Tregs differentiated from naive CD4+ T cells were decreased despite the elevated absolute counts of CD4+ cells in LAD-1 patients. Serum IL-23 levels were elevated in LAD-1 patients. Post-curdlan stimulation, LAD-1 patient-derived PBMCs produced more IL-17A. Additionally, the percentages of CD18-deficient Th17 cells expanded from total or naïve CD4+ T cells were higher. The blood ILC3 subset was significantly elevated in LAD-1. Finally, LAD-1 PBMCs showed defects in trans-well migration and proliferation and were more resistant to apoptosis. Defects in de novo generation of Tregs from CD18-deficient naïve T cells and elevated Th17s, and ILC3s in LAD-1 patients' peripheral blood suggest a type 3-skewed immunity and may contribute to LAD-1-associated autoimmune symptoms.

The Resilience Scale for Parents of Children with Cancer: Scale development and psychometric evaluation.

OBJECTIVE: This study aimed to develop a Resilience Scale for Parents of Children with Cancer (RSP-CC) designed specifically for parents of children with cancer and to evaluate its psychometric properties. METHODS: Based on the Resilience Model for Families of Children with Cancer, items were created after an extensive literature review and evaluated through expert consultation and a pilot study. Psychometric evaluation was conducted with the parents of 601 children with cancer in the pediatric hematology oncology services of different hospitals in the Ankara and Kayseri provinces in Turkey. RESULTS: A 4-factor structure was illustrated by exploratory factor analysis and confirmed by confirmatory factor analysis, explaining 62.192% of the total variance. In the reliability analysis of the scale, Interclass correlation = 0.993 and Cronbach's alpha = 0.994 were found for the scale. Robust correlation coefficients were found between test-retest, and the correlation between the two measurements was statistically significant (r = 0.990; p Ë‚ 0.001). As a result, the validity of a 24-item scale structure consisting of 4 dimensions was validated. CONCLUSIONS: It may be said that the RSP-CC meets the necessary criteria to examine the resilience in parents of children aged 0-18 with a cancer diagnosis, and its psychometric properties are reasonable sufficient.

Aceruloplasminemia presenting with microcytic anemia in a Turkish boy due to a novel pathogenic variant.

Aceruloplasminemia inherited autosomal recessively in the ceruloplasmin gene is a progressive disease with iron accumulation in various organs such as the brain, liver, pancreas, and retina. Ceruloplasmin gene encodes ceruloplasmin protein, which has ferroxidase activity and is involved in copper and iron metabolism. Progressive neurotoxicity, retinopathy, and diabetes may develop in about 40-60 decades. In addition, microcytic anemia accompanied by high ferritin and low ceruloplasmin level that develop at earlier ages can be first manifestation. Iron chelation may be utilized in the treatment to reduce the toxicity. Early diagnosis and treatment may delay the onset of symptoms. A 14-year-old male patient was followed up with microcytic anemia since an eight-years old. Anemia was accompanied by microcytosis, high ferritin, and low copper and ceruloplasmin levels. A novel homozygous c.690delG variant was detected in ceruloplasmin by whole exome sequencing. Clinical, laboratory and imaging findings of the patient demonstrated aceruloplasminemia. We present a boy with persistent microcytic anemia of the first manifestation at the age of eight, as the youngest case of aceruloplasminemia in the literature. Thereby, aceruloplasminemia should be kept in mind in the etiology of microcytic anemia whose cause couldn't found in childhood.

International retrospective study of allogeneic hematopoietic cell transplantation for activated PI3K-delta syndrome.

BACKGROUND: Activated phosphoinositide 3-kinase delta syndrome (APDS) is a combined immunodeficiency with a heterogeneous phenotype considered reversible by allogeneic hematopoietic cell transplantation (HCT). OBJECTIVES: This study sought to characterize HCT outcomes in APDS. METHODS: Retrospective data were collected on 57 patients with APDS1/2 (median age, 13 years; range, 2-66 years) who underwent HCT. RESULTS: Pre-HCT comorbidities such as lung, gastrointestinal, and liver pathology were common, with hematologic malignancy in 26%. With median follow-up of 2.3 years, 2-year overall and graft failure-free survival probabilities were 86% and 68%, respectively, and did not differ significantly by APDS1 versus APDS2, donor type, or conditioning intensity. The 2-year cumulative incidence of graft failure following first HCT was 17% overall but 42% if mammalian target of rapamycin inhibitor(s) (mTORi) were used in the first year post-HCT, compared with 9% without mTORi. Similarly, 2-year cumulative incidence of unplanned donor cell infusion was overall 28%, but 65% in the context of mTORi receipt and 23% without. Phenotype reversal occurred in 96% of evaluable patients, of whom 17% had mixed chimerism. Vulnerability to renal complications continued post-HCT, adding new insights into potential nonimmunologic roles of phosphoinositide 3-kinase not correctable through HCT. CONCLUSIONS: Graft failure, graft instability, and poor graft function requiring unplanned donor cell infusion were major barriers to successful HCT. Post-HCT mTORi use may confer an advantage to residual host cells, promoting graft instability. Longer-term post-HCT follow-up of more patients is needed to elucidate the kinetics of immune reconstitution and donor chimerism, establish approaches that reduce graft instability, and assess the completeness of phenotype reversal over time.