Overt Immunodeficiency Research Articles

Reassessing the Risk of Severe Parvovirus B19 Infection in the Immunocompetent Population: A Call for Vigilance in the Wake of Resurgence.

Despite Parvovirus B19 (B19V) generally causing mild or asymptomatic infections, and only certain high-risk groups such as hematological or immunocompromised patients and pregnant women tending to develop complications, several factors challenge the assumption of a "benign" clinical course in immunocompetent adults and adolescents. A significant proportion of the population may harbor undiagnosed health conditions or genetic predispositions that could render them more susceptible to severe B19V complications. These could include mild hematological disorders, immune dysregulation not resulting in overt immunodeficiency, or underlying cardiac conditions. Concurrent infections with other pathogens, even seemingly minor ones, could synergistically increase the severity of B19V infection, leading to more pronounced clinical manifestations. While not definitively proven, the possibility of emerging B19V strains with increased virulence or altered tissue tropism cannot be entirely discounted. Additionally, the period of pandemic-related restrictions likely led to reduced B19V circulation, potentially resulting in a cohort of young adults with limited natural immunity, making them more vulnerable to infection. Potential clinical consequences include atypical and severe presentations, even in individuals without known risk factors. The traditional focus on B19V primarily as a pediatric concern might lead to underdiagnosis or delayed diagnosis in adults, potentially hindering timely intervention and management. A surge in B19V-related complications, even if individually mild, could collectively strain healthcare resources, particularly in settings with limited capacity or pre-existing pressures. Possible recommendations are to heighten clinical awareness with a high index of suspicion for B19V infection in adults and adolescents presenting with compatible symptoms, even in the absence of classic risk factors. Additionally, expanding testing criteria and enhancing public health surveillance efforts would be prudent.

Role of Super Immune Activation Secondary to Infection in the Context of Cancer

By 2008, it was estimated that there were about 12.7 million new cases of cancer worldwide, resulting in 7.6 million deaths. We are aware of the heterogeneity that exists and that it is impossible to link its development in any organ to a single pathophysiological mechanism. The greatest risk factor for developing cancer is aging, as age is directly proportional to accumulated aberrations and exposure to carcinogens. Most cancers occur in people who have no overt immunodeficiency. It is evident, then, that tumor cells must develop mechanisms to escape or evade the immune system in immunocompetent hosts. The main mechanisms of innate immunity against viruses are inhibition of infection by type I interferons and NK cell-mediated death of infected cells. The hypothesis is that perhaps the ability of epigenetic modification, which varies from virus to virus, is not exclusively reduced to the ability to activate genes that lead to cancer; but also randomly empower the organism to activate tumor suppressor genes.

Reduced frequency of cytotoxic CD56dim CD16+ NK cells leads to impaired antibody-dependent degranulation in EBV-positive classical Hodgkin lymphoma

Around 30–50% of classical Hodgkin lymphoma (cHL) cases in immunocompetent individuals from industrialized countries are associated with the B-lymphotropic Epstein-Barr virus (EBV). Although natural killer (NK) cells exhibit anti-viral and anti-tumoral functions, virtually nothing is known about quantitative and qualitative differences in NK cells in patients with EBV+ cHL vs. EBV- cHL. Here, we prospectively investigated 36 cHL patients without known immune suppression or overt immunodeficiency at diagnosis. All 10 EBV+ cHL patients and 25 out 26 EBV- cHL were seropositive for EBV antibodies, and EBV+ cHL patients presented with higher plasma EBV DNA levels compared to EBV- cHL patients. We show that the CD56dim CD16+ NK cell subset was decreased in frequency in EBV+ cHL patients compared to EBV- cHL patients. This quantitative deficiency translates into an impaired CD56dim NK cell mediated degranulation toward rituximab-coated HLA class 1 negative lymphoblastoid cells in EBV+ compared to EBV- cHL patients. We finally observed a trend to a decrease in the rituximab-associated degranulation and ADCC of in vitro expanded NK cells of EBV+ cHL compared to healthy controls. Our findings may impact on the design of adjunctive treatment targeting antibody-dependent cellular cytotoxicity in EBV+ cHL.

Isolated Nocardiosis, an Unrecognized Primary Immunodeficiency?

Nocardiosis is an infectious disease caused by the gram-positive bacterium Nocardia spp. Although it is commonly accepted that exposure to Nocardia is almost universal, only a small fraction of exposed individuals develop the disease, while the vast majority remain healthy. Nocardiosis has been described as an “opportunistic” disease of immunocompromised patients, suggesting that exposure to the pathogen is necessary, but a host predisposition is also required. Interestingly, increasing numbers of nocardiosis cases in individuals without any detected risk factors, i.e., without overt immunodeficiency, are being reported. Furthermore, a growing body of evidence have shown that selective susceptibility to a specific pathogen can be caused by a primary immunodeficiency (PID). This raises the question of whether an undiagnosed PID may cause nocardiosis affecting otherwise healthy individuals. This review summarizes the specific clinical and microbiological characteristics of patients with isolated nocardiosis published during the past 30 years. Furthermore, it gives an overview of the known human immune mechanisms to fend off Nocardia spp. obtained from the study of PIDs and patients under immunomodulatory therapies.

Impact of comorbidities on the performance of interferon-gamma release assay in an elderly Greek population without overt immunodeficiency

Background The prevalence of latent tuberculosis infection (LTBI) increases with age. Interferon-gamma release assay (IGRA) is a T-cell based assay widely used for the detection of LTBI.Objectives To identify the prevalence of LTBI among an elderly Greek population using IGRA and to evaluate comorbidities associated with LTBI.Methods Individuals aged at least 65 years who were non-immunocompromised and had no history of active tuberculosis infection (TBI) underwent IGRA to identify LTBI. Participant characteristics were compared between the LTBI and non-LTBI groups. Interferon-gamma (INFγ) levels were analysed in each group.Results A total of 130 (38.7%) participants with LTBI and 206 (61.3%) participants without LTBI were included. Multivariate logistic regression analysis identified the following features that were independently associated with a positive IGRA result: female sex (odds ratio [OR]: 0.45; 95% confidence interval [CI]: 0.28-0.72; P=0.001), chronic heart failure (OR: 0.41; 95% CI: 0.22-0.77; P=0.005), history of major surgery (OR: 0.55; 95% CI: 0.33-0.92; P=0.022) and Charlson Comorbidity Index >3 (OR: 3.06; 95% CI: 1.46-6.40; P=0.003). Production of stimulated INFγ was significantly lower in the non-LTBI group.Conclusions Female sex, history of chronic heart failure and history of any surgical intervention were independently associated with a negative IGRA result, and CCI >3 was associated with a positive IGRA result. These results indicate careful interpretation of IGRA is required among elderly individuals with these characteristics.

Candidate Predisposition Variants in Kaposi Sarcoma as Detected by Whole-Genome Sequencing.

Familial clustering of classic Kaposi sarcoma (CKS) is rare with, approximately 100 families reported to date. We studied 2 consanguineous families, 1 Iranian and 1 Israeli, with multiple cases of adult CKS and without overt underlying immunodeficiency. We performed genome-wide linkage analysis and whole-genome sequencing to discover the putative genetic cause for predisposition. A 9-kb homozygous intronic deletion in RP11-259O2.1 in the Iranian family and 2 homozygous variants, 1 in SCUBE2 and the other in CDHR5, in the Israeli family were identified as possible candidates. The presented variants provide a robust starting point for validation in independent samples.

No Overt Clinical Immunodeficiency Despite Immune Biological Abnormalities in Patients With Constitutional Mismatch Repair Deficiency.

Immunoglobulin class-switch recombination (CSR) and somatic hypermutations (SHMs) are prerequisites for antibody and immunoglobulin receptor maturation and adaptive immune diversity. The mismatch repair (MMR) machinery, consisting of homologs of MutSα, MutLα, and MutSβ (MSH2/MSH6, MLH1/PMS2, and MSH2/MSH3, respectively) and other proteins, is involved in CSR, primarily acting as a backup for nonhomologous end-joining repair of activation-induced cytidine deaminase-induced DNA mismatches and, furthermore, in addition to error-prone polymerases, in the repair of SHM-induced DNA breaks. A varying degree of antibody formation defect, from IgA or selective IgG subclass deficiency to common variable immunodeficiency and hyper-IgM syndrome, has been detected in a small number of patients with constitutional mismatch repair deficiency (CMMRD) due to biallelic loss-of-function mutations in one of the MMR genes (PMS2, MSH6, MLH1, or MSH2). To elucidate the clinical relevance of a presumed primary immunodeficiency (PID) in CMMRD, we systematically collected clinical history and laboratory data of a cohort of 15 consecutive, unrelated patients (10 not previously reported) with homozygous/compound heterozygous mutations in PMS2 (n = 8), MSH6 (n = 5), and MLH1 (n = 2), most of whom manifested with typical malignancies during childhood. Detailed descriptions of their genotypes, phenotypes, and family histories are provided. Importantly, none of the patients showed any clinical warning signs of PID (infections, immune dysregulation, inflammation, failure to thrive, etc.). Furthermore, we could not detect uniform or specific patterns of laboratory abnormalities. The concentration of IgM was increased in 3 out of 12, reduced in 3 out of 12, and normal in 6 out of 12 patients, while concentrations of IgG and IgG subclasses, except IgG4, and of IgA, and specific antibody formation were normal in most. Class-switched B memory cells were reduced in 5 out of 12 patients, and in 9 out of 12 also the CD38hiIgM− plasmablasts were reduced. Furthermore, results of next generation sequencing-based analyses of antigen-selected B-cell receptor rearrangements showed a significantly reduced frequency of SHM and an increased number of rearranged immunoglobulin heavy chain (IGH) transcripts that use IGHG3, IGHG1, and IGHA1 subclasses. T cell subsets and receptor repertoires were unaffected. Together, neither clinical nor routine immunological laboratory parameters were consistently suggestive of PID in these CMMRD patients, but previously shown abnormalities in SHM and rearranged heavy chain transcripts were confirmed.

Streptococcus bovis \u2013 unusual etiology of meningitis in a neonate with Down syndrome: a case report

BackgroundCommon etiological agents of neonatal meningitis include group B Streptococcus, Escherichia coli, and Staphylococcus aureus. Here we report a rare pathogen – Streptococcus bovis – causing meningitis in a premature neonate with Down syndrome.Case presentationA 26-day-old Asian male neonate with Down syndrome presented with a history of high-grade fever, poor sucking, poor cry, and reduced activity. On admission, he was febrile and had features of circulatory collapse. A cerebrospinal fluid examination confirmed bacterial meningitis and blood culture isolated the causative organism: group D Streptococcus, which was verified as Streptococcus bovis biotype 2. An echocardiogram did not show evidence of infective endocarditis.ConclusionsThis is probably the first report of neonatal meningitis due to Streptococcus bovis in a child with Down syndrome. Although our patient did not show features of overt immunodeficiency, subtle abnormalities in his immune system would have predisposed him to infection with this unusual organism. This case highlights the need for considering unusual pathogens when managing serious infections in children with Down syndrome.

Watch Out! Syphilis Is Back – Case Series of Four Cases of Ocular syphilis

Background Syphilis is an ulcerative sexually transmitted genital infection caused by Treponema pallidum, which is a member of the order Spirochaetales, family Spirochaetaceae, and genus Treponema. The incidence rate of Syphilis has been steadily rising since 2000; from 2.1 cases per 100,000 population to up to 7.5 cases per 100,000 population in 2014–2015 (the highest rate since 1994). In the state of West Virginia, we have witnessed an increase in the number of cases from 0.5 cases per 100,000 population in 2011, to 5.9 cases per 100,000 population in 2015. Systemic symptoms can include cardiovascular and neurological manifestations. We report to your attention four cases of syphilis mainly with neurological and ocular manifestations.Methods We report a series of four cases of neurosyphilis we encountered between 2013 and 2016. Main presentation of all four cases was ocular; primarily redness and photophobia. Diagnosis was confirmed by standard ophthalmological examination with positive initial rapid plasma regain titers (RPR) and fluorescent treponemal antibody absorption testing (FTA-ABS). The cerebrospinal fluid venereal disease research laboratory test (CSF-VDRL) was positive in two of the four cases (in which lumbar puncture was performed). Two of the four cases suffered from an overt immunodeficiency (HIV and laryngeal cancer on chemotherapy) and subjects of all four cases confessed to high-risk sexual behaviors. All four cases were managed with continuous infusions of Penicillin G potassium 24 million International Units for 14 days with variable response.ResultsResponse to treatment was variable in that initial complete resolution was achieved in one patient (Case #3), another (Case #1) was retreated in 6 months due to rising RPR titers on follow-up with subsequent improvement. Two patients were lost to follow-up (Cases #2 and #4).Conclusion Sir William Osler reportedly said: “He who knows syphilis knows medicine”. The steady rise in the incidence of Syphilis warrants that health care providers consider such a diagnosis in the evaluation of suggestive neurological and ocular manifestations in predisposed patients. We also stress on the importance of follow-up to detect failure of initial treatment.Disclosures All authors: No reported disclosures.

Reduced TGF‑βR signaling results in increased T cell activation without autoinflammatory disease

Abstract Transforming growth factor-β receptor (TGF-βR) signaling is important in regulating the proliferation and differentiation of CD4+ T cells, but how modulating the level of signaling can affect T cell fate remains unclear. We have created a mouse model of Loeys-Dietz syndrome (LDS), an autosomal dominant disease caused by mutations in genes encoding the TGF-βR, by targeting a missense mutation (M318R) to the endogenous murine Tgfbr1 locus. LDS patients exhibit an increased propensity for allergic disease, but no overt immunodeficiency or autoimmune disease. A higher percentage of CD4+ T cells in Tgfbr1M318R/+ mice exhibited a memory phenotype and produced enhanced levels of cytokines including IFN-γ, IL-13, IL-17, and IL-10 upon stimulation, but no autoimmunity was observed. In contrast, mice lacking TGF-βR2 specifically in T cells demonstrate exaggerated IFN-γ production and widespread autoinflammatory disease. While naïve CD4+ T cells from Tgfbr1M318R/+ mice were less likely to upregulate Foxp3 during in vitro culture with recombinant TGF-β, paradoxically, increased percentages and numbers of suppressive Foxp3+ regulatory T cells (Tregs) were observed in vivo, which may indicate a role for increased proliferation or survival of thymically-derived Tregs. The effects of the Tgfbr1M318R/+on T cells appear to be cell intrinsic. We observed no differences in T cells derived from WT bone marrow used to reconstitute irradiated Tgfbr1M318R/+ or WT hosts, while Tgfbr1M318R/+ bone marrow co-transferred with WT bone marrow into WT hosts gave rise to more activated CD4+ T cells and a higher frequency of Foxp3+ cells. These data suggest that partially abrogated TGF-β signaling leads to unexpected effects on T cell development and function.

Mutations in XRCC4 cause primordial dwarfism without causing immunodeficiency.

In successive reports from 2014 to 2015, X-ray repair cross-complementing protein 4 (XRCC4) has been identified as a novel causative gene of primordial dwarfism. XRCC4 is indispensable for non-homologous end joining (NHEJ), the major pathway for repairing DNA double-strand breaks. As NHEJ is essential for V(D)J recombination during lymphocyte development, it is generally believed that abnormalities in XRCC4 cause severe combined immunodeficiency. Contrary to expectations, however, no overt immunodeficiency has been observed in patients with primordial dwarfism harboring XRCC4 mutations. Here, we describe the various XRCC4 mutations that lead to disease and discuss their impact on NHEJ and V(D)J recombination.

Immunotoxicity Monitoring in a Population Exposed to Polychlorinated Biphenyls.

The relationship between polychlorinated biphenyl (PCB) burden and several indicators of immune function was investigated as part of the HELPcB (Health Effects in High-Level Exposure to PCB) program, offering bio-monitoring to workers, relatives, and neighbors exposed to PCBs by a German transformers and capacitors recycling company. The present retrospective observational study evaluates the correlation of plasma levels of total PCBs, five indicator congeners (28, 101, 138, 153, 180), and seven dioxin-like congeners (105, 114, 118, 156, 157, 167, 189) with several parameters of immune function. The cross-sectional study was performed immediately after the end of exposure (258 subjects), and one (218 subjects), and two (177 subjects) years later. At the first time point, measurements showed significant positive correlation between congeners with low to medium chlorination and the relative proportion of CD19 positive B-cells among lymphocytes, as well as a negative correlation of PCB114 with serum IgM, and of PCB 28 with suppressor T-cell and NK-cell numbers. Congeners with a high degree of chlorination, in particular PCB157 and 189, were positively associated with expression of the activation marker CD25 on T-cells in the cohort of the second time point. No associations between PCB levels and IFN-y production by T-cells and killing by NK-cells were found. In conclusion, there were several effects on the cellular composition of adaptive immunity, affecting both T- and B-cells. However, the values were not generally outside the reference ranges for healthy adult individuals and did not indicate overt functional immunodeficiency, even in subjects with the uppermost PCB burden.

A homozygous STIM1 mutation impairs store-operated calcium entry and natural killer cell effector function without clinical immunodeficiency

A homozygous STIM1 mutation impairs store-operated calcium entry and natural killer cell effector function without clinical immunodeficiency

XRCC4 deficiency in human subjects causes a marked neurological phenotype but no overt immunodeficiency

Nonhomologous end-joining (NHEJ) is the major DNA double-strand break (DSB) repair mechanism in human cells. The final rejoining step requires DNA ligase IV (LIG4) together with the partner proteins X-ray repair cross-complementing protein 4 (XRCC4) and XRCC4-like factor. Patients with mutations in genes encoding LIG4, XRCC4-like factor, or the other NHEJ proteins DNA-dependent protein kinase catalytic subunit and Artemis are DSB repair defective and immunodeficient because of the requirement for NHEJ during V(D)J recombination. We found a patient displaying microcephaly and progressive ataxia but a normal immune response. We sought to determine pathogenic mutations and to describe the molecular pathogenesis of the patient. We performed next-generation exome sequencing. We evaluated the DSB repair activities and V(D)J recombination capacity of the patient's cells, as well as performing a standard blood immunologic characterization. We identified causal mutations in the XRCC4 gene. The patient's cells are radiosensitive and display the most severe DSB repair defect we have encountered using patient-derived cell lines. In marked contrast, a V(D)J recombination plasmid assay revealed that the patient's cells did not display the junction abnormalities that are characteristic of other NHEJ-defective cell lines. The mutant protein can interact efficiently with LIG4 and functions normally in in vitro assays and when transiently expressed in vivo. However, the mutation makes the protein unstable, and it undergoes proteasome-mediated degradation. Our findings reveal a novel separation of impact phenotype: there is a pronounced DSB repair defect and marked clinical neurological manifestation but no clinical immunodeficiency.

Essential engagement of Toll-like receptor 2 in initiation of early protective Th1 response against rough variants of Mycobacterium abscessus.

Although Mycobacterium abscessus (M. abscessus) is becoming more prevalent in patients without overt immunodeficiency, little is known about the factors that contribute to disease susceptibility. This study was undertaken to investigate how Toll-like receptor 2 (TLR2) functionally contributes to the generation of protective immunity against M. abscessus in a morphotype-specific manner. We found that Tlr2-/- mice were extremely susceptible to an intravenous (i.v.) model of infection by M. abscessus rough variants, displaying uncontrolled infection in the lungs and a significantly lower survival rate than with wild-type (WT) mice. This uncontrolled infection resulted from failures in the following processes: (i) production of the crucial cytokines gamma interferon (IFN-γ), tumor necrosis factor alpha (TNF-α), and interleukin 12p70 (IL-12p70); (ii) early infiltration of neutrophils, monocytes, and dendritic cells (DCs) in the lungs of Tlr2-/- mice; (iii) rapid influx of CD4+ and CD8+ T cells; and (iv) the expansion of memory/effector T cells. Notably, systemic administration of M. abscessus culture filtrate-treated syngeneic DCs from WT mice greatly strengthened immune priming in vivo, resulting in a dramatic reduction in bacterial growth and improved long-term survival in Tlr2-/- mice, with a recovery of protective immunity. Our findings demonstrate that TLR2 is an essential contributor to instructive and effector immunity during M. abscessus infection in a morphotype-specific manner.

Esophageal Candidiasis in a Patient With Uncontrolled Diabetes Mellitus and Recurrent Abdominal Pain, Symptomatic Or Incidental? A Case Report and Brief Literature Review

Esophageal candidiasis (EC) is a common opportunistic infection in patients with impaired cellular immunity, such as human immunodeficiency virus (HIV) infection. However, it can also be found in individuals with certain predisposing conditions like uncontrolled diabetes mellitus (DM) and the use of certain medications. We report a 54-year-old female with past medical history of DM, hypertension and hyperlipidemia who presented to the ER with worsening periumbilical and epigastric pain for 2 days. She had multiple similar presentations requiring admissions to different hospitals and had undergone extensive workup over the past year. She only had transient improvement from these hospitalizations. Esophagogastroduodenoscopy (EGD) performed on day 2 of admission revealed extensive creamy pseudomembranous exudate through the entire length of esophagus confirmed as Candida albicans by brush scraping analysis. She received oral fluconazole with significant relief of her symptoms over the next couple of weeks. Although EC remains asymptomatic in the majority of patients and is only detected incidentally on EGD, its diagnosis and treatment can provide significant symptomatic relief in many patients. EC should be considered as a potential diagnosis in the appropriate clinical setting even in patients with no evidence of overt immunodeficiency. J Med Cases. 2015;6(11):523-526 doi: http://dx.doi.org/10.14740/jmc2337w

EPSTEIN-BARR VIRUS ROLE IN ONCOGENESIS

We now recognize that the Epstein-Barr virus (EBV) plays a pivotal role in the development of some lymphomas and lymphoproliferative disorders that include B-cell, T-cell and NK-cell processes, and epithelial and mesenchymal tumors. While over recent years, EBV associated lymphomas are becoming increasingly recognized in patients without overt immunodeficiency. Improved understanding of the biology of these lymphomas and the role that EBV plays in their pathogenesis has paved the way for improved therapies targeted at critical signaling pathways as well as the development of novel cellular therapies. This review discusses the unique cytomorphology, clinical and immunophenotype signs and ancillary studies required to diagnose EBV-related neoplasms.

Changes in the levels of mannan-binding lectin and ficolins during head-down tilted bed rest.

Spaceflight studies and ground-based analogues of microgravity indicate a weakening of human immunity. Mannan-binding lectin (MBL) and H-, L-, and M-ficolin together constitute the lectin pathway and mediate the clearance of pathogens through complement activation. We hypothesized that simulated microgravity may weaken human innate immune functions and studied the impact of 6° head-down tilted bed rest (HDT) for 21 d on MBL and ficolin levels. Within a 6-mo period, seven men underwent two periods of HDT. Blood samples were analyzed for MBL, H-, L-, and M-ficolin, mannose-binding lectin-associated protein of 44 kDa (MAp44), and collectin liver 1 (CL-L1) by time-resolved immunofluorometric assays (TRIFMA). We observed well-defined individual preintervention levels of MBL and ficolins. Remarkably similar intraindividual changes occurred for MBL and MBL levels decreased (mean 282 ng · ml⁻¹) in the recovery phase. Conversely, CL-L1, a protein with MBL-like properties, increased (mean 102 ng · ml⁻¹) during the recovery phase. M-ficolin increased (mean 79 ng · ml⁻¹) within the first 2 d of HDT, followed by a decrease (mean 112 ng · ml⁻¹) during the recovery phase. L-ficolin increased (mean 304 ng · ml⁻¹) during HDT, while H-ficolin was essentially unaffected. MAp44, a down-regulator of the lectin pathway, decreased initially (mean 78 ng · ml⁻¹) in the recovery phase followed by an increase (mean 131 ng · ml⁻¹). Alterations in MBL and ficolin levels were modest and with our current knowledge do not lead to overt immunodeficiency. Pronounced changes occurred when the subjects resumed the upright position. In selected individuals, these changes appear to be a conserved response to HDT.

Variants in Nicotinamide Adenine Dinucleotide Phosphate Oxidase Complex Components Determine Susceptibility to Very Early Onset Inflammatory Bowel Disease

The colitis observed in patients with very early onset inflammatory bowel disease (VEOIBD; defined as onset of disease at younger than 6 years of age) often resembles that of chronic granulomatous disease (CGD) in extent and features of colonic inflammation observed by endoscopy and histology. CGD is a severe immunodeficiency caused by defects in the genes that encode components of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex. We investigated whether variants in genes that encode NADPH oxidase components affect susceptibility to VEOIBD using independent approaches. We performed targeted exome sequencing of genes that encode components of NADPH oxidases (cytochrome b light chain and encodes p22(phox) protein; cytochrome b-245 or NADPH oxidase 2, and encodes Nox2 or gp91(phox); neutrophil cytosol factor 1 and encodes p47 (phox) protein; neutrophil cytosol factor 2 and encodes p67 (phox) protein; neutrophil cytosol factor 4 and encodes p40 (phox) protein; and Ras-related C3 botulinum toxin substrate 1 and 2) in 122 patients with VEOIBD diagnosed at The Hospital for Sick Children, University of Toronto, from 1994 through 2012. Gene variants were validated in an independent International Early Onset Pediatric IBD Cohort Study cohort of patients with VEOIBD. In a second approach, we examined Tag single nucleotide polymorphisms in a subset of patients with VEOIBD in which the NOX2 NADPH oxidase genes sequence had been previously analyzed. We then looked for single nucleotide polymorphisms associated with the disease in an independent International Early Onset Pediatric IBD Cohort Study cohort of patients. We analyzed the functional effects of variants associated with VEOIBD. Targeted exome sequencing and Tag single nucleotide polymorphism genotyping identified 11 variants associated with VEOIBD; the majority of patients were heterozygous for these variants. Expression of these variants in cells either reduced oxidative burst or altered interactions among proteins in the NADPH oxidase complex. Variants in the noncoding regulatory and splicing elements resulted in reduced levels of proteins, or expression of altered forms of the proteins, in blood cells from VEOIBD patients. We found that VEOIBD patients carry heterozygous functional hypomorphic variants in components of the NOX2 NADPH oxidase complex. These do not cause overt immunodeficiency, butinstead determine susceptibility to VEOIBD. Specific approaches might be developed to treat individual patients based on their genetic variant.

Allogeneic Stem Cell Transplant Offers Cure for Intractable Childhood Enteropathy

s / Biol Blood Marrow Transplant 20 (2014) S72eS90 S90 26 patients were treated with 27 SCTs at two centres between 1999 and 2013. All patients had onset of symptoms before 7 years of age and were either TPN dependent (n1⁄413) or had enteropathy refractory to at least 3 immunosuppressive agents (n1⁄413) prior to transplant. Patients with overt primary immunodeficiency were excluded. 8 of 26 patients had a confirmed pathogenic mutation identified (IPEX, XIAP, IL10, IL10Ra) and 18/26 remain genetically undefined. 11 patients (42%) had previously undergone gut resections +/defunctioning stoma formation and 63% had suffered life threatening complications prior to transplant (sepsis, lymphoproliferative disease, vasculitis). 22 SCTs were performed with fully HLA matched donors (8 family, 14 unrelated), and 5 with 9/10 mismatched donors. With exception of 2 sibling donor grafts conditioned, all patients received reduced toxicity conditioning, the majority with alemtuzumab 1mg/kg, fludarabine 150mg/m2 + either treosulphan 42g/m2 (n1⁄412) or melphalan 140mg/m2 (n1⁄410). Transplant related mortality was 23% (n1⁄46) from GVHD, conditioning toxicity, viral infections and pulmonary hypertension. One patient died from diabetic ketoacidosis unrelated to SCT following a successful transplant. 96% of patients engrafted, but one patient required a second graft following rejection. The majority of patients (22/26) had full donor chimerism at last follow-up, and the remaining 4 patients have stable mixed chimerism with 73-94% donor chimerism within the lymphoid lineage. 8 patients (30%) developed significant aGVHD but the incidence of cGVHD was low (n1⁄41, 4%). At amedian follow-up of 51months,19 patients are alive,17 of whom have had sustained improvement in their enteropathy. 8 surviving patients (89%) on TPN pre-transplant have now discontinued and 14 (78%) are off all immunosuppression. Our data demonstrate that reduced toxicity conditioned SCT can cure the majority of patients with IEOC even in the absence of a defined genetic defect. We believe that given the severity of this condition, SCT offers patients major improvement in quality of life at an acceptable risk of toxicity and that further studies of this approach in well-defined patients are warranted.