Disseminated and Congenital Toxoplasmosis in a Mother and Child With Activated PI3-Kinase δ Syndrome Type 2 (APDS2): Case Report and a Literature Review of Toxoplasma Infections in Primary Immunodeficiencies

Phosphoinositide 3-kinase (PI3K) plays an integral role in lymphocyte function. Mutations in PIK3CD and PIK3R1, encoding the PI3K p110δ and p85α subunits, respectively, cause increased PI3K activity and result in immunodeficiency with immune dysregulation. We describe here the first cases of disseminated and congenital toxoplasmosis in a mother and child who share a pathogenic mutation in PIK3R1 and review the mechanisms underlying susceptibility to severe Toxoplasma gondii infection in activated PI3Kδ syndrome (APDS) and in other forms of primary immunodeficiency

Expansion of immunoglobulin-secreting cells and defects in B cell tolerance in Rag-dependent immunodeficiency

The contribution of B cells to the pathology of Omenn syndrome and leaky severe combined immunodeficiency (SCID) has not been previously investigated. We have studied a mut/mut mouse model of leaky SCID with a homozygous Rag1 S723C mutation that impairs, but does not abrogate, V(D)J recombination activity. In spite of a severe block at the pro–B cell stage and profound B cell lymphopenia, significant serum levels of immunoglobulin (Ig) G, IgM, IgA, and IgE and a high proportion of Ig-secreting cells were detected in mut/mut mice. Antibody responses to trinitrophenyl (TNP)-Ficoll and production of high-affinity antibodies to TNP–keyhole limpet hemocyanin were severely impaired, even after adoptive transfer of wild-type CD4+ T cells. Mut/mut mice produced high amounts of low-affinity self-reactive antibodies and showed significant lymphocytic infiltrates in peripheral tissues. Autoantibody production was associated with impaired receptor editing and increased serum B cell–activating factor (BAFF) concentrations. Autoantibodies and elevated BAFF levels were also identified in patients with Omenn syndrome and leaky SCID as a result of hypomorphic RAG mutations. These data indicate that the stochastic generation of an autoreactive B cell repertoire, which is associated with defects in central and peripheral checkpoints of B cell tolerance, is an important, previously unrecognized, aspect of immunodeficiencies associated with hypomorphic RAG mutations

WHIM syndrome myelokathexis reproduced in the NOD/SCID mouse xenotransplant model engrafted with healthy human stem cells transduced with C-terminus–truncated CXCR4

WHIM(warts, hypogammaglobulinemia, recurrent bacterial infection, and myelokathexis) syndrome is a rare immunodeficiency caused in many cases by autosomal dominant C-terminal truncation mutations in the chemokine receptor CXCR4. A prominent and unexplained feature of WHIM is myelokathexis (hypercellularity with apoptosis of mature myeloid cells in bone marrow and neutropenia). We transduced healthy human CD34(+) peripheral blood–mobilized stem cells (PBSCs) with retrovirus vector encoding wild-type (wt) CXCR4 or WHIM-type mutated CXCR4 and studied these cells ex vivo in culture and after engraftment in a nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mouse xenograft model. Neither wt CXCR4 nor mutated CXCR4 transgene expression itself enhanced apoptosis of neutrophils arising in transduced PBSC cultures even with stimulation by a CXCR4 agonist, stromal cell–derived factor-1 (SDF-1 [CXCL12]). Excess wt CXCR4 expression by transduced human PBSCs enhanced marrow engraftment, but did not affect bone marrow (BM) apoptosis or the release of transduced leukocytes into PB. However, mutated CXCR4 transgene expression further enhanced BM engraftment, but was associated with a significant increase in apoptosis of transduced cells in BM and reduced release of transduced leukocytes into PB. We conclude that increased apoptosis of mature myeloid cells in WHIM is secondary to a failure of marrow release and progression to normal myeloid cell senescence, and not a direct effect of activation of mutated CXCR4

Human syndromes of immunodeficiency and dysregulation are characterized by distinct defects in T-cell receptor repertoire development

Background Human immunodeficiencies characterized by hypomorphic mutations in critical developmental and signaling pathway genes allow for the dissection of the role of these genes in the development of the T-cell receptor (TCR) repertoire and the correlation of alterations of the TCR repertoire with diverse clinical phenotypes. Objective The presence of T cells in patients with Omenn syndrome (OS) and patients with atypical presentations of severe combined immunodeficiency gene mutations presents an opportunity to study the effects of the causal genes on TCR repertoires and provides a window into the clinical heterogeneity observed. Methods We performed deep sequencing of TCRβ complementarity-determining region 3 (CDR3) regions in subjects with a series of immune dysregulatory conditions caused by mutations in recombination activating gene 1/2 (RAG 1/2), IL-2 receptor γ (IL2RG), and ζ chain-associated protein kinase 70 (ZAP70); a patient with atypical DiGeorge syndrome; and healthy control subjects. Results We found that patients with OS had marked reductions in TCRβ diversity compared with control subjects, as expected. Patients with atypical presentations of RAG or IL2RG mutations associated with autoimmunity and granulomatous disease did not have altered overall diversity but instead had skewed V-J pairing and skewed CDR3 amino acid use. Although germline TCRs were more abundant and clonally expanded in patients with OS, nongermline sequences were expanded as well. TCRβ from patients with RAG mutations had less junctional diversity and smaller CDR3s than patients with OS caused by other gene mutations and healthy control subjects but relatively similar CDR3 amino acid use. Conclusions High-throughput TCR sequencing of rare immune disorders has demonstrated that quantitative TCR diversity can appear normal despite qualitative changes in repertoire and strongly suggests that in human subjects RAG enzymatic function might be necessary for normal CDR3 junctional diversity

Gene correction for SCID-X1 in long-term hematopoietic stem cells

Gene correction in hematopoietic stem cells could be a powerful way to treat monogenic diseases of the blood and immune system. Here the authors develop a strategy using CRISPR-Cas9 and an aAdeno-Associated vVirus(AAV)-delivered IL2RG cDNA to correct X-linked sSevere Ccombined iImmunodeficiency (SCID-X1) with a high success rate

Author Correction: Gene correction for SCID-X1 in long-term hematopoietic stem cells

The original version of this Article omitted the following from the Acknowledgements: “G.B. acknowledges the support from the Cancer Prevention and Research Institute of Texas (RR140081 and RR170721).”This has now been corrected in both the PDF and HTML versions of the Article

Author Correction: Gene correction for SCID-X1 in long-term hematopoietic stem cells.

An amendment to this paper has been published and can be accessed via a link at the top of the paper

Gene correction for SCID-X1 in long-term hematopoietic stem cells.

Gene correction in human long-term hematopoietic stem cells (LT-HSCs) could be an effective therapy for monogenic diseases of the blood and immune system. Here we describe an approach for X-linked sSevere cCombined iImmunodeficiency (SCID-X1) using targeted integration of a cDNA into the endogenous start codon to functionally correct disease-causing mutations throughout the gene. Using a CRISPR-Cas9/AAV6 based strategy, we achieve up to 20% targeted integration frequencies in LT-HSCs. As measures of the lack of toxicity we observe no evidence of abnormal hematopoiesis following transplantation and no evidence of off-target mutations using a high-fidelity Cas9 as a ribonucleoprotein complex. We achieve high levels of targeting frequencies (median 45%) in CD34+ HSPCs from six SCID-X1 patients and demonstrate rescue of lymphopoietic defect in a patient derived HSPC population in vitro and in vivo. In sum, our study provides specificity, toxicity and efficacy data supportive of clinical development of genome editing to treat SCID-Xl

DataSheet_1_Case report: Persistent shedding of a live vaccine-derived rubella virus in a young man with severe combined immunodeficiency and cutaneous granuloma.pdf

A young man with X-linked severe combined immunodeficiency developed a persistent vaccine-derived rubella virus (VDRV) infection, with the emergence of cutaneous granulomas more than fifteen years after receipt of two doses of measles-mumps-rubella (MMR) vaccine. Following nasopharyngeal swab (NP) collection, VDRV was detected by real-time polymerase chain reaction (RT-qPCR) and sequencing, and live, replication-competent VDRV was isolated in cell culture. To assess duration and intensity of viral shedding, sequential respiratory samples, one cerebrospinal fluid sample, and two urine samples were collected over 15 months, and VDRV RNA was detected in all samples by RT-qPCR. Live VDRV was cultured from nine of the eleven respiratory specimens and from one urine specimen. To our knowledge, this was the first reported instance of VDRV cultured from respiratory specimens or from urine. To assess potential transmission to close contacts, NP specimens and sera were collected from all household contacts, all of whom were immunocompetent and previously vaccinated with MMR. VDRV RNA was not detected in any NP swabs from the contacts, nor did serologic investigations suggest VDRV transmission to any contacts. This report highlights the need to understand the prevalence and duration of VDRV shedding in granuloma patients and to estimate the risk of VDRV transmission to immune and non-immune contacts.</p

Table_1_Case report: Persistent shedding of a live vaccine-derived rubella virus in a young man with severe combined immunodeficiency and cutaneous granuloma.docx

A young man with X-linked severe combined immunodeficiency developed a persistent vaccine-derived rubella virus (VDRV) infection, with the emergence of cutaneous granulomas more than fifteen years after receipt of two doses of measles-mumps-rubella (MMR) vaccine. Following nasopharyngeal swab (NP) collection, VDRV was detected by real-time polymerase chain reaction (RT-qPCR) and sequencing, and live, replication-competent VDRV was isolated in cell culture. To assess duration and intensity of viral shedding, sequential respiratory samples, one cerebrospinal fluid sample, and two urine samples were collected over 15 months, and VDRV RNA was detected in all samples by RT-qPCR. Live VDRV was cultured from nine of the eleven respiratory specimens and from one urine specimen. To our knowledge, this was the first reported instance of VDRV cultured from respiratory specimens or from urine. To assess potential transmission to close contacts, NP specimens and sera were collected from all household contacts, all of whom were immunocompetent and previously vaccinated with MMR. VDRV RNA was not detected in any NP swabs from the contacts, nor did serologic investigations suggest VDRV transmission to any contacts. This report highlights the need to understand the prevalence and duration of VDRV shedding in granuloma patients and to estimate the risk of VDRV transmission to immune and non-immune contacts.</p