Two novel CD40LG gene mutations causing X-linked hyper IgM syndrome in Vietnamese patients.

The X-linked hyper IgM syndrome is a primary immunodeficiency disorder (PID) due to mutations in the CD40LG gene. Hyper IgM syndrome is characterized by the absence or decreased levels of IgG and IgA and normal or elevated IgM levels in serum. Affected patients become susceptible to infections such as pneumonia, diarrhea, and skin ulcer types. Hematopoietic stem cell transplantation is the only treatment currently available and ideally performed before the age of 10 years. Early, accurate diagnosis will contribute to the effective treatment for patients with hyper IgM. The patients from different Vietnamese families who have been diagnosed with hyper IgM at The Allergy, Immunology and Rheumatology Department, Vietnam National Hospital Pediatrics, were performed a genetic analysis using whole exome sequencing. The mutations were confirmed by the Sanger sequencing method in patients and their families. The influence of the mutations was predicted with the in silico analysis tools: PROVEAN, SIFT, PolyPhen-2, and MutationTaster. In this study, two novel mutations (p.Thr254fs and p.Leu138Phe) in the CD40LG gene were found in Vietnamese patients with X-linked hyper IgM syndrome. Our results contribute to the general understanding of the etiology of the disease and can help diagnose the different forms of PID.

CD40 Ligand Deficiency.

CD40 ligand deficiency (CD40L), currently classified as an inborn error of immunity affecting cellular and humoral immunity, prevalently emerges in boys within the first two years of life. It manifests itself as a decrease in serum IgG, IgA and IgE, with normal or high IgM, defects in T cell proliferation, and decrease in soluble CD40L. These accompany sinopulmonary and/or gastrointestinal infections, and there may be infections caused by pyogenic bacteria, opportunistic infections, autoimmune diseases, and neoplasms. Mild and moderate cases of this deficiency may respond well to prophylactic antibiotic therapy or to human immunoglobulin replacement therapy, in addition to the early treatment of infections. Severe cases can be treated with hematopoietic stem cell transplantation, which allows the healing of such patients, rather than sequelae and a poor progression. Thus, its differential diagnosis with other inborn errors of immunity is essential, especially CD40 deficiency and variable common immunodeficiency; the reason why we have proposed the present literature review.

A Novel CD40L Mutation Associated with X-Linked Hyper IgM Syndrome in a Chinese Family.

Background: Mutations in CD40 ligand gene (CD40L) affecting immunoglobulin class-switch recombination and somatic hypermutation can result in X-Linked Hyper IgM Syndrome (HIGM1, XHIGM), a kind of rare serious primary immunodeficiency disease (PID) characterized by the deficiency of IgG, IgA and IgE and normal or increased serum concentrations of IgM. The objective of this study is to explain genotype-phenotype correlation and highlight the mutation responsible for a Chinese male patient with XHIGM.Methods: Whole exome sequencing (WES) and Sanger sequencing validation were performed to identify and validate the likely pathogenic mutation in the XHIGM family.Results: The results of the sequencing revealed that a new causative mutation in CD40L (c.714delT in exon 5, p.F238Lfs*4) which leads to the change in amino acids (translation terminates at the third position after the frameshift mutation) appeared in the proband. As his mother in the family was carrier with this heterozygous mutation, the hemizygous mutation in this patient came from his mother indicating that genetic mode of XHIGM is X-linked recessive inheritance.Conclusion: This study broadens our knowledge of the mutation in CD40L and lays a solid foundation for prenatal diagnosis and genetic counseling for the XHIGM family.

Pneumocystis jirovecii pneumonia as an initial manifestation of hyper-IgM syndrome in an infant: A case report.

RATIONALE: Pneumocystis jirovecii causes severe pneumonia in immunocompromised hosts. Human immunodeficiency virus infection, malignancy, solid organ or hematopoietic cell transplantation, and primary immune deficiency compose the risk factors for Pneumocystis pneumonia (PCP) in children, and PCP can be an initial clinical manifestation of primary immune deficiency. PATIENT CONCERNS: A 5-month-old infant presented with cyanosis and tachypnea. He had no previous medical or birth history suggesting primary immune deficiency. He was diagnosed with interstitial pneumonia on admission. DIAGNOSES: He was diagnosed with PCP, and further evaluations revealed underlying X-linked hyper-IgM syndrome. INTERVENTIONS: He was treated with trimethoprim/sulfamethoxazole for PCP, and eventually received allogeneic hematopoietic cell transplantation for hyper-IgM syndrome. OUTCOMES: Twenty months have passed after transplantation without severe complications. LESSONS: PCP should be considered in infants presenting with severe interstitial pneumonia even in the absence of evidence of immune deficiency. Primary immune deficiency should also be suspected in infants diagnosed with PCP.

CD40 ligand deficiency: treatment strategies and novel therapeutic perspectives.

INTRODUCTION: CD40 ligand (CD40L) deficiency or X-linked Hyper-IgM syndrome is a severe primary immunodeficiency caused by mutations in the CD40L gene. Despite currently available treatments, CD40L-deficient patients remain susceptible to life-threatening infections and have poor long term survival. Areas covered: Here, we discuss clinical and immunological characteristics of CD40L deficiency as well as current therapeutic strategies used for patient management. This review highlights that beyond B cell defects, patients' susceptibility to opportunistic pathogens might be due to impaired T cell and innate immune responses. In this context, we discuss how better knowledge of CD40L function and regulation may result in the development of new treatments. Expert opinion: Despite the introduction of hematopoietic stem-cell transplantation, immunoglobulin replacement, granulocyte colony-stimulating factor (G-CSF) administration, and prophylactic antibiotic therapies, life-threatening infections still cause high morbidity and mortality among CD40L-deficient patients. The reasons for this inadequate response to current therapies remains poorly understood, but recent reports suggest the involvement of CD40L-CD40 interaction in early stages of the innate immune system ontogeny. The development of novel gene therapeutic approaches and the use of redirected immunotherapies represent alternative treatment methods that could offer reduced morbidity and mortality rates for patients with CD40L deficiency.

X-linked Hyper IgM Syndrome Presenting as Pulmonary Alveolar Proteinosis.

PURPOSE: X-linked hyper IgM syndrome (XHIGM) is a combined immunodeficiency caused by mutations in the CD40 ligand (CD40L) gene that typically results in decreased or absent CD40L expression on activated T cells, leading to defective class switching and somatic hypermutation. We describe an infant who presented with respiratory failure due to pulmonary alveolar proteinosis (PAP) with a novel damaging missense mutation in the CD40L gene. METHODS: Whole exome sequencing (WES) was used to identify a mutation in the CD40L gene. CD40L expression and function were determined by flow cytometry. RESULTS: A 5-month-old previously-healthy male presented with respiratory failure and diffuse pulmonary ground glass opacities on CT scan of the chest. Laboratory evaluation revealed an undetectable IgG, normal IgA, and elevated IgM. A bronchoalveolar lavage demonstrated pulmonary alveolar proteinosis. WES demonstrated a c.608G > C mutation in the CD40L gene resulting in p.R203T. Flow cytometry demonstrated normal CD40L expression on activated T cells but absent binding of CD40-Ig to CD40L on activated patient T cells. CONCLUSIONS: The clinical manifestations of XHIGM in our patient had several unique features, including the presentation with PAP, normal serum IgA, and expression of non-functional CD40L on activated T cells. To our knowledge, this is the first published case of PAP in a patient with XHIGM.

Targeted gene editing restores regulated CD40L function in X-linked hyper-IgM syndrome.

Loss of CD40 ligand (CD40L) expression or function results in X-linked hyper-immunoglobulin (Ig)M syndrome (X-HIGM), characterized by recurrent infections due to impaired immunoglobulin class-switching and somatic hypermutation. Previous attempts using retroviral gene transfer to correct murine CD40L expression restored immune function; however, treated mice developed lymphoproliferative disease, likely due to viral-promoter-dependent constitutive CD40L expression. These observations highlight the importance of preserving endogenous gene regulation in order to safely correct this disorder. Here, we report efficient, on-target, homology-directed repair (HDR) editing of the CD40LG locus in primary human T cells using a combination of a transcription activator-like effector nuclease-induced double-strand break and a donor template delivered by recombinant adeno-associated virus. HDR-mediated insertion of a coding sequence (green fluorescent protein or CD40L) upstream of the translation start site within exon 1 allowed transgene expression to be regulated by endogenous CD40LG promoter/enhancer elements. Additionally, inclusion of the CD40LG 3'-untranslated region in the transgene preserved posttranscriptional regulation. Expression kinetics of the transgene paralleled that of endogenous CD40L in unedited T cells, both at rest and in response to T-cell stimulation. The use of this method to edit X-HIGM patient T cells restored normal expression of CD40L and CD40-murine IgG Fc fusion protein (CD40-muIg) binding, and rescued IgG class switching of naive B cells in vitro. These results demonstrate the feasibility of engineered nuclease-directed gene repair to restore endogenously regulated CD40L, and the potential for its use in T-cell therapy for X-HIGM syndrome.

Hematopoietic Stem Cell Transplantation for CD40 Ligand Deficiency: Single Institution Experience.

BACKGROUND: X-linked hyper-IgM syndrome (X-HIGM) due to mutations in the gene encoding CD40 ligand results in failure of Ig class switching and an increased propensity for recurrent sinopulmonary and other infections, and thus decreased life expectancy. Allogeneic hematopoietic stem cell transplantation (HSCT) is curative, but long-term follow-up data are limited. PROCEDURES: We conducted a retrospective analysis of seven patients who have undergone allogeneic HSCT for HIGM syndrome at Duke University Medical Center. RESULTS: Median age at transplant was 5.2 years (range 0.7-19.3). None of the patients had active hepatic or pulmonary disease immediately prior to transplant, but all had a history of serious infections. Five patients received myeloablative conditioning, and two patients received reduced intensity conditioning. Graft sources included bone marrow, peripheral blood, and unrelated umbilical cord blood. Post-transplantation complications included veno-occlusive disease, hemorrhagic cystitis, adenoviremia, and cryptosporidium recurrence in one patient each. Two patients developed acute GVHD grades II-IV that resolved promptly with treatment and none developed extensive chronic GVHD. All patients are intravenous IgG-independent and 6/7 have normal antibody titers. Immunoglobulin (Ig) A levels normalized in all but one patient and T and B cell numbers and function are otherwise normal in all. All patients are alive at a median follow-up of 9.7 (range 9.7-16.1) years post-transplantation with predominantly donor chimerism and no recurrent infections. CONCLUSIONS: Allogeneic HSCT results in excellent survival and sustained immune reconstitution in patients with CD40 ligand deficiency using both myeloablative and reduced intensity conditioning approaches and various graft sources, including bone marrow, peripheral blood, and umbilical cord blood.

Hematopoietic stem cell transplant for hyper-IgM syndrome due to CD40L defects: A single-center experience.

HIGMI is a disease with a high risk for morbidity and mortality. HSCT has been shown to be a curative option. This study retrospectively reviewed and analyzed data from five patients who received HSCT at King Faisal Specialist Hospital & Research Centre (KFSH&RC) in Riyadh, Saudi Arabia, between 2005 and 2013. Five patients with HIGMI syndrome underwent HSCT at a median age of 41 months (range, 9-72 months). The median time from diagnosis to transplantation was 30 months (range, 5-58 months). For all five patients, the donors were HLA-identical siblings. In three patients, the conditioning regimen was composed of BU and CY. Fludarabine and melphalan with either ATG or alemtuzumab was used in two patients. For GVHD prophylaxis, cyclosporine was used in two patients, and the combination of cyclosporine and MTX was used in three patients. The survival rate was 100%, with a median follow-up of 69 months (range, 13-100 months). All patients engrafted. Two patients developed acute GVHD. Four patients showed complete immune recovery with positive CD40L expression in activated T cells and discontinued IVIG replacement. HSCT in early stage from an HLA-matched sibling donor is potentially effective at curing the disease.

Transitional cell carcinoma in a patient with X-linked hyperimmunoglobulin M syndrome.

Patients with X-linked hyperimmunoglobulin M syndrome (XHIGM) have a defective CD40-CD40 ligand system and further immunoglobulin class-switching. They may present with recurrent infection and malignancy involving the liver, pancreas or biliary tract. We report here a case of poorly differentiated transitional cell carcinoma in a young man with XHIGM even on regular treatment and discuss the possible pathogenesis. Given that the triggering of the CD40-CD40 ligand system has been found to improve tumor immunogenicity in recent studies, future immunotherapy targeting the CD40 ligand for these patients may be feasible to prolong their survival.

Clinical features and genetic analysis of 20 Chinese patients with X-linked hyper-IgM syndrome.

X-linked hyper-IgM syndrome (XHIGM) is one type of primary immunodeficiency diseases, resulting from defects in the CD40 ligand/CD40 signaling pathways. We retrospectively analyzed the clinical and molecular features of 20 Chinese patients diagnosed and followed up in hospitals affiliated to Shanghai Jiao Tong University School of Medicine from 1999 to 2013. The median onset age of these patients was 8.5 months (range: 20 days-21 months). Half of them had positive family histories, with a shorter diagnosis lag. The most common symptoms were recurrent sinopulmonary infections (18 patients, 90%), neutropenia (14 patients, 70%), oral ulcer (13 patients, 65%), and protracted diarrhea (13 patients, 65%). Six patients had BCGitis. Six patients received hematopoietic stem cell transplantations and four of them had immune reconstructions and clinical remissions. Eighteen unique mutations in CD40L gene were identified in these 20 patients from 19 unrelated families, with 12 novel mutations. We compared with reported mutation results and used bioinformatics software to predict the effects of mutations on the target protein. These mutations reflected the heterogeneity of CD40L gene and expanded our understanding of XHIGM.

Immunoglobulin class switch recombination deficiency type 1 or CD40 ligand deficiency: from bedside to bench and back again.

The immunoglobulin class switch recombination deficiency or hyper-IgM syndrome is characterized by normal or elevated serum IgM and low serum levels of other immunoglobulins. Since the first reported patient with hyper-IgM, more than 200 patients with this phenotype resulted from CD40 ligand deficiency have been reported. However, in addition to this common finding, they presented with different manifestations like opportunistic infections, autoimmunity and malignancies each of them are worth a detailed look. In this review, we will focus on different underlying mechanisms of these presentations to review what we have learned from our patients. In the end, we will discuss different treatment options available for these patients using this knowledge.

Partial immune reconstitution of X-linked hyper IgM syndrome with recombinant CD40 ligand.

X-linked hyper IgM syndrome (XHM) is a combined immune deficiency disorder caused by genetic alterations in CD40 ligand. The purpose of this study was to investigate the safety and efficacy of recombinant CD40 ligand (rCD40L) in the treatment of the disease. Three children were administered rCD40L subcutaneously 3 times per week at 0.03 mg/kg for 22 weeks, and after a 12-week drug-free interval, the dose was increased to 0.05 mg/kg for an additional 22 weeks of treatment. Although specific antibody responses to T cell-dependent antigens was lacking, administration of rCD40 resulted in acquisition of the capacity to mount cutaneous delayed type hypersensitivity reactions that disappeared during the drug-free interval as well as the postbiologic follow-up period. With rCD40L treatment, patient T cells developed a new capacity to respond to T-cell mitogens with synthesis of IFN-γ and TNF-α. Intracellular cytokine staining studies showed that both CD4(+) and CD8(+) T cells participated in this response. Finally, CD40L therapy was associated with changes in lymph node size and architecture based on comparison of biopsies taken before and after therapy. This clinical study showed that rCD40L is capable of improving T cell-immune function in patients with XHM.

A tissue-specific, activation-inducible, lentiviral vector regulated by human CD40L proximal promoter sequences.

The application of new protocols for gene therapy against monogenic diseases requires the development of safer therapeutic vectors, particularly in the case of diseases in which expression of the mutated gene is subject to fine regulation, as it is with CD40L (CD154). CD40L, the gene mutated in the X-linked hyper-immunoglobulin M syndrome (HIGM1), is tightly regulated to allow surface expression of its product only on T cells stimulated by antigen encounter. Previous studies in an HIGM1 animal model showed that transduction of progenitor cells corrected the syndrome but caused a thymic lymphoproliferative disease because of the unregulated expression of the transgene by constitutive vectors. To develop a tissue-specific, activation-inducible, lentiviral vector (LV) for gene therapy to counter HIGM1, we have constructed two self-inactivating LVs, pCD40L-eGFP and pCD40L-CD40L, regulated by a 1.3 kb fragment of the human CD40L proximal promoter. The expression of pCD40L-eGFP LV is restricted to cells in which mRNA transcripts of the endogenous CD40L gene can be detected. Moreover, the expression of the reporter gene in primary T lymphocytes depends on the activation state of the cells. Remarkably, primary HIGM1 lymphocytes transduced with pCD40L-CD40L LV expressed CD40L only after T-cell stimulation. Therefore, the CD40L-promoter-driven vectors are able to achieve a near-physiological expression pattern that follows very closely that of the endogenous CD40L gene.

Primer trasplante de progenitores hematopoyéticos en un paciente con inmunodeficiencia primaria en Uruguay: síndrome de hiper IgM ligafo al X / First hematopoietic stem cell transplantation in a patient with primary inmunodeficiency in Uruguay: X-linked hyper IgM syndrome

Introducción: el trasplante alogénico de progenitores hematopoyéticos (TPH) es el único tratamiento de las inmunodeficiencias congénitas severas con potencial curativo. El síndrome hiper-IgM ligado al X tipo 1 (HIGM-1) -causado por mutaciones en el gen que codifica el ligando CD40- es una inmunodeficiencia primaria (IDP) con alta morbimortalidad a pesar de tratamientos de soporte adecuados, debido a infecciones recurrentes y colangiopatía. Describimos el primer TPH en una IDP en nuestro país en un niño con HIGM-1 con enfermedad hepática ya establecida. Métodos: un paciente con HIGM-1 con infecciones reiteradas, falla de crecimiento, y colangiopatía documentada por biopsia hepática fue sometido a TPH alogénico de su hermana HLA idéntica. El condicionamiento fue no mieloablativo con fludarabina, melfalan y globulina antitimocítica. Resultados: el niño lleva dos años del TPH. El quimerismo es 100% del donante. Está libre de infecciones, independiente de inmunoglobulina intravenosa y su colangiopatía impresiona resuelta. Los estudios de laboratorio confirman la corrección del defecto inmunológico. Conclusión: el TPH alogénico de donante HLA idéntico realizado con condicionamiento no mieloablativo permitió la reconstitución inmune en un niño con HIGM-1 y colangiopatía preexistente, sin toxicidad hepática severa.

CD40 ligand deficiency: neurologic sequelae with radiographic correlation.

Patients with CD40 ligand deficiency are susceptible to central nervous system infections, but to date the neurologic progression or long-term outcome of central nervous system complications have not been reported in detail. Characterizing the central nervous system complications of immune deficiencies can lead to the identification of new pathogens. For this study, clinical data were reviewed on patients with both CD40 ligand deficiency and neurodegeneration, identified from a larger cohort of 31 patients. Five patients had progressive neurologic and cognitive decline in the absence of clinical signs of acute fulminant encephalitis, with anatomic brain abnormalities and high mortality (60%). Despite multiple evaluations, no pathogens were identified in four patients, all of whom were on standard intravenous immunoglobulin therapy at illness presentation. This clinical phenotype of progressive decline without acute fulminant encephalitis is similar to chronic enteroviral encephalitis in X-linked agammaglobulinemia, another condition with severe humoral immune defects. Whether infection secondary to subtherapeutic levels of central nervous system immunoglobulin G (IgG), inadequately protective levels of serum IgG, or impaired CD40 ligand-dependent IgG-independent antiviral responses contributed remains undetermined. Emerging gene-chip techniques applied in patients with primary immune deficiencies may identify heretofore unknown viruses. Prospective neurocognitive and evaluation of patients with CD40 ligand deficiency may identify affected patients before overt clinical signs appear.

ARDS as presenting symptom in an infant with CD40L deficiency (Hyper-IgM syndrome Type 1).

We report on a 4 month old male infant with respiratory syncytial virus (RSV) infection leading to acute respiratory distress syndrome (ARDS). A diagnostic algorithm including extended infectiological and immunological work-up revealed absence of CD40-ligand. ARDS was treated successfully with a complex respiratory therapy plus intravenous immunoglobulin substitution. Molecular analysis detected mutations in the CD40L gene (Hyper-IgM syndrome Type 1). The case underlines the importance of an extended diagnostic work-up in an uncommonly severe course of respiratory infection in early infancy.