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.

A Novel Case of IFNAR1 Deficiency Identified a Common Canonical Splice Site Variant in DOCK8 in Western Polynesia: The Importance of Validating Variants of Unknown Significance in Under-Represented Ancestries.

Advanced genomic technologies such as whole exome or whole genome sequencing have improved diagnoses and disease outcomes for individuals with genetic diseases. Yet, variants of unknown significance (VUS) require rigorous validation to establish disease causality or modification, or to exclude them from further analysis. Here, we describe a young individual of Polynesian ancestry who in the first 13 mo of life presented with SARS-CoV-2 pneumonia, severe enterovirus meningitis and adenovirus gastroenteritis, and severe adverse reaction to MMR vaccination. Genomic analysis identified a previously reported pathogenic homozygous variant in IFNAR1 (c.1156G > T, p.Glu386* LOF), which is common in Western Polynesia. Moreover, a new and putatively deleterious canonical splice site variant in DOCK8 was also found in homozygosity (c.3234 + 2T > C). This DOCK8 variant is common in Polynesians and other under-represented ancestries in large genomic databases. Despite in silico bioinformatic predictions, extensive in vitro and ex vivo analysis revealed the DOCK8 variant likely be neutral. Thus, our study reports a novel case of IFNAR1 deficiency, but also highlights the importance of functional validation of VUS, including those predicted to be deleterious, and the pressing need to expand our knowledge of the genomic architecture and landscape of under-represented populations and ancestries.

Umbilical Cord Blood Cell Clearance Post-Infusion in Immune-Competent Children with Cerebral Palsy.

Umbilical cord blood cells have therapeutic potential for neurological disorders, through a paracrine mechanism of action. A greater understanding of the safety and immunological effects of allogeneic donor cord blood cells in the context of a healthy recipient immune system, such as in cerebral palsy, is needed. This study aimed to determine how quickly donor cord blood cells were cleared from the circulation in children with cerebral palsy who received a single intravenous infusion of 12/12 human leucocyte antigen (HLA)-matched sibling cord blood cells. Twelve participants with cerebral palsy aged 2-12 years received cord blood cell infusions as part of a phase I trial of umbilical blood infusion for cerebral palsy. Digital droplet PCR analysis of DNA copy number variants specific to donor and recipient was used to assess donor DNA clearance at five timepoints post-infusion, a surrogate measure of cell clearance. Donor cells were cleared by 3 months post-infusion in 11/12 participants. When detected, donor DNA was at a fraction of 0.01-0.31% of total DNA with no signs of graft-versus-host disease in any participant. The donor DNA clearance times provided by this study have important implications for understanding the safety of allogeneic cord blood cell infusion for cerebral palsy and translational tissue engineering or regenerative medicine research in other disorders.

Longitudinal antibody responses to peanut following probiotic and peanut oral immunotherapy (PPOIT) in children with peanut allergy.

INTRODUCTION: Probiotic and Peanut Oral Immunotherapy (PPOIT) is effective at inducing sustained unresponsiveness (SU) at end-of-treatment and this effect persists up to four years post-treatment, referred to as persistent SU. We sought to evaluate (i) how PPOIT altered peanut-specific humoral immune indices, and (ii) how such longitudinal indices relate to persistent SU. METHODS: Longitudinal serum/plasma levels of whole peanut- and peanut component- (Ara-h1, -h2, -h3, -h8, -h9) specific-IgE (sIgE) and specific-IgG4 (sIgG4) antibodies were measured by ImmunoCAP and salivary peanut-specific-IgA (sIgA) by ELISA in children (n=62) enrolled in the PPOIT-001 randomised trial from baseline (T0) to 4-years post-treatment (T5). Multivariate regression analyses of log-transformed values were used for point-in-time between group comparisons. Generalised estimating equations (GEE) were used for longitudinal comparisons between groups. RESULTS: PPOIT was associated with changes in sIgE and sIgG4 over time. sIgE levels were significantly reduced post-treatment [T5, PPOIT v.s. Placebo ratio of geometric mean (GM): Ara-h1 0.07, p=0.008; Ara-h2 0.08, p=0.007; Ara-h3 0.15, p=0.021]. sIgG4 levels were significantly increased by end-of-treatment (T1, PPOIT v.s. Placebo ratio of GM: Ara-h1 3.77, p=0.011; Ara-h2 17.97, p<0.001; Ara-h3 10.42, p<0.001) but levels in PPOIT group decreased once treatment was stopped and returned to levels comparable with Placebo group by T5. Similarly, salivary peanut sIgA increased during treatment, as early as 4 months of treatment (PPOIT v.s. Placebo, ratio of GM: 2.04, p=0.014), then reduced post-treatment. CONCLUSION: PPOIT was associated with broad reduction in peanut specific humoral responses which may mediate the clinical effects of SU that persists to 4-years post-treatment.

Safety of sibling cord blood cell infusion for children with cerebral palsy.

Cerebral palsy (CP) is a nonprogressive neurological disorder and the most common physical disability of childhood. There is no cure for CP, but stem cells have the potential to improve brain injury and hence function. This phase 1 clinical trial investigated the safety of the intravenous infusion of full-matched sibling cord blood cells for children with CP aged 1 to 16 years. Preliminary efficacy outcomes were also investigated. Twelve participants received 12/12 HLA-matched sibling cord blood cell infusions. One treatable serious adverse reaction to cryoprotectant was observed, and no adverse reactions occurred beyond 24 h after infusion. Gross motor function measure (GMFM-66) scores did not improve compared with baseline beyond what could be expected from developmental levels, and participants had varied changes in the Quality of Upper Extremity Skills Test (QUEST) and Vineland Adaptive Behavior Scales (VABS-II) scores. In conclusion, matched sibling cord blood cell infusion for children with CP is relatively safe when conducted in an appropriate facility. Australian and New Zealand Clinical Trials Registry (ACTRN12616000403437) and Clinicaltrials.gov (NCT03087110).

A novel pathogenic variant in the corneodesmosin gene causing generalized inflammatory peeling skin syndrome with marked eosinophilia and trichorrhexis invaginata.

Generalized inflammatory peeling skin syndrome (PSS) is a rare autosomal recessive genodermatosis caused by loss-of-function disease-causing variants of the corneodesmosin gene (CDSN), resulting in excessive shedding of the superficial layers of the epidermis. We describe a case of generalized inflammatory PSS in an infant, presenting at day two of life with ichthyosiform erythroderma and superficial peeling of the skin. Hair microscopy showed trichorrhexis invaginata. Normal amounts of skin LEKT1, a product of SPINK5 on immunohistochemical staining excluded a diagnosis of Netherton syndrome. Genetic analysis revealed a homozygous novel complete CDSN deletion, estimated 4.6 kb in size, supporting the diagnosis of generalized inflammatory PSS.

Detection of interferon alpha and beta receptor subunit 1 (IFNAR1) loss-of-function Glu386∗ variant by tri-allelic genotyping.

Mutations of the human interferon alpha and beta receptor subunit 1 (IFNAR1) gene are associated with severe viral infections. Individuals homozygous for the Glu386∗ variant have impaired type I interferon signalling and can suffer severe illness when exposed to certain viruses and live attenuated virus vaccines. Glu386∗ heterozygotes are clinically unaffected, but can pass the variant allele to their descendants. We aimed to develop an assay that can identify IFNAR1 Glu386∗ homozygotes and heterozygotes to support urgent clinical diagnosis, and that can use dried blood spots (DBS) sent at ambient temperature to overcome geographical logistical challenges in the South Pacific region. The tri-allelic genotyping assay interrogates a single nucleotide polymorphism (rs201609461) located in IFNAR1. The reference allele G encodes for wild-type IFNAR1. Minor alleles A (c.1156G>A) and T (c.1156G>T) encode for Glu386Lys and a truncated IFNAR1 protein (p.Glu386∗), respectively. Synthetic oligonucleotides were mixed in equal molar ratio to create six different genotypes which were randomly assigned to 960 genotyping reactions by R software. Three different fluorescence probes were designed to discriminate the three alleles (G, T and A) within a pair of flanking primers in a single genotyping reaction. The assay discriminated all three alleles using DBS from Guthrie cards randomly spiked with synthetic oligonucleotides. We correctly identified all the different genotypes in 960 reactions in these blinded experiments. These findings validate the genotyping assay for rapidly identifying the IFNAR1 Glu386∗ variant from DBS.

Phenotypic spectrum in a family with a novel RAC2 p.I21S dominant-activating mutation.

Objectives: Dominant-activating (DA) lesions in RAC2 have been reported in 18 individuals to date. Some have required haematopoietic stem cell transplantation (HSCT) for their (severe) combined immunodeficiency syndrome phenotype. We aimed to investigate clinical and cellular features of a kindred harbouring a novel variant in RAC2 p.Ile21Ser (I21S) to better understand DA lesions' phenotypic spectrum. Methods: Clinical and immunological information was collated for seven living individuals from the same kindred with RAC2 p.I21S. We evaluated neutrophil morphology, RAC2 protein expression and superoxide production using freshly isolated neutrophils stimulated with phorbol-12-myristate-13-acetate (PMA) and N-formyl-MetLeuPhe (fMLP). Results: Patient 1 (P1, aged 11, male) has a history of bacterial suppurative otitis media, viral and bacterial cutaneous infections. P1's siblings (P2, P3), mother (P4), maternal aunt (P5) and uncle (P6) have similar infection histories. P1's maternal cousin (P7) presented with Burkitt's lymphoma at age 9. All affected individuals are alive and none has required HSCT to date. They have chronic lymphopenia affecting the CD4+T and B-cell compartments. P1-3 have isolated reduction in IgM levels whereas the adults universally have normal immunoglobulins. Specific antibody responses are preserved. Affected individuals have neutrophil vacuolation, and their neutrophils have enhanced superoxide production compared to healthy controls. Conclusion: RAC2 p.I21S is an activating variant causing notable morphological and functional abnormalities similar to other reported DA mutations. This novel variant expands the broad clinical phenotypic spectrum of RAC2 DA lesions, emphasising the need to tailor clinical management according to patients' disease phenotype and severity.

A loss-of-function IFNAR1 allele in Polynesia underlies severe viral diseases in homozygotes.

Globally, autosomal recessive IFNAR1 deficiency is a rare inborn error of immunity underlying susceptibility to live attenuated vaccine and wild-type viruses. We report seven children from five unrelated kindreds of western Polynesian ancestry who suffered from severe viral diseases. All the patients are homozygous for the same nonsense IFNAR1 variant (p.Glu386*). This allele encodes a truncated protein that is absent from the cell surface and is loss-of-function. The fibroblasts of the patients do not respond to type I IFNs (IFN-α2, IFN-ω, or IFN-ß). Remarkably, this IFNAR1 variant has a minor allele frequency >1% in Samoa and is also observed in the Cook, Society, Marquesas, and Austral islands, as well as Fiji, whereas it is extremely rare or absent in the other populations tested, including those of the Pacific region. Inherited IFNAR1 deficiency should be considered in individuals of Polynesian ancestry with severe viral illnesses.

Different impact of aspirin on renal progression in patients with predialysis advanced chronic kidney disease with or without previous stroke.

BACKGROUND: The benefit of reducing the risk of stroke against increasing the risk of renal progression associated with antiplatelet therapy in patients with advanced chronic kidney disease (CKD) is controversial. METHODS: We enrolled 1301 adult patients with advanced CKD treated with erythropoiesis stimulating agents from January 1, 2002 to June 30, 2009 from the 2005 Longitudinal Health Insurance Database in Taiwan. All of the patients were followed until the development of the primary or secondary endpoints, or the end of the study (December 31, 2011). The primary endpoint was the development of ischemic stroke, and the secondary endpoints included hospitalization for bleeding events, cardiovascular mortality, all-cause mortality, and renal failure. The adjusted cumulative probability of events was calculated using multivariate Cox proportional regression analysis. RESULTS: Adjusted survival curves showed that the usage of aspirin was not associated with ischemic stroke, hospitalization for bleeding events, cardiovascular mortality or all-cause mortality, however, it was significantly associated with renal failure. In subgroup analysis, aspirin use was associated with renal failure in the patients with no history of stroke (HR, 1.41; 95% CI, 1.14-1.73), and there was a borderline interaction between previous stroke and the use of aspirin on renal failure (interaction p=0.0565). CONCLUSIONS: There was no significant benefit in preventing ischemic stroke in the patients with advanced CKD who received aspirin therapy. Furthermore, the use of aspirin was associated with the risk of renal failure in the patients with advanced CKD without previous stroke.

Long-term clinical and immunological effects of probiotic and peanut oral immunotherapy after treatment cessation: 4-year follow-up of a randomised, double-blind, placebo-controlled trial.

BACKGROUND: Oral immunotherapy has attracted much interest as a potential treatment for food allergy, yet little is known about its long-term effects. We aimed to assess long-term outcomes in participants who completed a randomised, double-blind, placebo-controlled trial of combined probiotic and peanut oral immunotherapy (PPOIT), which was previously shown to induce desensitisation and 2-week sustained unresponsiveness. METHODS: All participants who completed the PPOIT randomised trial were eligible to participate in this follow-up study 4 years after treatment cessation. Peanut intake and adverse reactions to peanut in the 4 years after treatment cessation were systematically documented with a structured questionnaire administered by allergy nurses. Additionally, participants were invited to undergo peanut skin prick tests, measurement of peanut sIgE and sIgG4 concentrations, and double-blind placebo-controlled peanut challenge to assess 8-week sustained unresponsiveness. FINDINGS: 48 (86%) of 56 eligible participants were enrolled in the follow-up study. Mean time since stopping treatment was 4·2 years in both PPOIT (SD 0·6) and placebo (SD 0·7) participants. Participants from the PPOIT group were significantly more likely than those from the placebo group to have continued eating peanut (16 [67%] of 24 vs one [4%] of 24; absolute difference 63% [95% CI 42-83], p=0·001; number needed to treat 1·6 [95% CI 1·2-2·4]). Four PPOIT-treated participants and six placebo participants reported allergic reactions to peanut after intentional or accidental intake since stopping treatment, but none had anaphylaxis. PPOIT-treated participants had smaller wheals in peanut skin prick test (mean 8·1 mm [SD 7·7] vs 13·3 mm [7·6]; absolute difference -5·2 mm [95% CI -10·3 to 0·0]; age-adjusted and sex-adjusted p=0·035) and significantly higher peanut sIgG4:sIgE ratios than placebo participants (geometric mean 67·3 [95% CI 10·3-440·0] vs 5·2 [1·2-21·8]; p=0·031). Seven (58%) of 12 participants from the PPOIT group attained 8-week sustained unresponsiveness, compared with one (7%) of 15 participants from the placebo group (absolute difference 52% [95% CI 21-82), p=0·012; number needed to treat 1·9 [95% CI 1·2-4·8]). INTERPRETATION: PPOIT provides long-lasting clinical benefit and persistent suppression of the allergic immune response to peanut. FUNDING: Murdoch Childrens Research Institute and Australian Food Allergy Foundation.

MMP-2 serum concentrations predict mortality in hemodialysis patients: a 5-year cohort study.

BACKGROUND: We evaluated the ability of matrix metalloproteinase (MMP)-2, MMP-9, myeloperoxidase, osteopontin and stromal cell-derived factor 1 to predict mortality in hemodialysis (HD) patients. METHODS: One hundred forty HD patients were enrolled and followed from December 2007 until December 2012. At the end of this 5-year period, data were compared between the patients who were alive and those who had died. RESULTS: The patients who alive were younger (56 vs. 63y), with lower frequency of diabetes mellitus (34.34% vs. 58.53%), higher concentrations of albumin (4.13 vs. 3.91mg/dl) and lower concentrations of MMP-2 (430.76 vs. 521.59ng/ml). Multivariate analysis showed that age (HR=1.03, p=0.02), diabetes mellitus (HR=2.395, p=0.012), albumin (HR=0.475, p=0.047) and MMP-2 (HR=1.003, p=0.005) were independent factors predicting mortality in HD patients. Receiver operating characteristic curve analysis showed that albumin (AUC=0.628, p=0.027) and MMP-2 (AUC=0.643, p=0.004) had a similar ability (p=0.76) to predict survival of HD patients. CONCLUSIONS: Compared with albumin, serum MMP-2 is a non-inferior prognostic marker for predicting the survival of HD patients.

Evaluation of Severe Combined Immunodeficiency and Combined Immunodeficiency Pediatric Patients on the Basis of Cellular Radiosensitivity.

Pediatric patients with severe or nonsevere combined immunodeficiency have increased susceptibility to severe, life-threatening infections and, without hematopoietic stem cell transplantation, may fail to thrive. A subset of these patients have the radiosensitive (RS) phenotype, which may necessitate conditioning before hematopoietic stem cell transplantation, and this conditioning includes radiomimetic drugs, which may significantly affect treatment response. To provide statistical criteria for classifying cellular response to ionizing radiation as the measure of functional RS screening, we analyzed the repair capacity and survival of ex vivo irradiated primary skin fibroblasts from five dysmorphic and/or developmentally delayed pediatric patients with severe combined immunodeficiency and combined immunodeficiency. We developed a mathematical framework for the analysis of γ histone 2A isoform X foci kinetics to quantitate DNA-repair capacity, thus establishing crucial criteria for identifying RS. The results, presented in a diagram showing each patient as a point in a 2D RS map, were in agreement with findings from the assessment of cellular RS by clonogenic survival and from the genetic analysis of factors involved in the nonhomologous end-joining repair pathway. We provide recommendations for incorporating into clinical practice the functional assays and genetic analysis used for establishing RS status before conditioning. This knowledge would enable the selection of the most appropriate treatment regimen, reducing the risk for severe therapy-related adverse effects.