Publications by authors named "Machiel H Jansen"

24 Publications

  • Page 1 of 1

Hematopoietic stem cell transplantation in a patient with proteasome-associated autoinflammatory syndrome (PRAAS).

J Allergy Clin Immunol 2021 Aug 17. Epub 2021 Aug 17.

Department of Pediatric Immunology, Rheumatology and Infectious Diseases, Emma Children's Hospital, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Department of Experimental Immunology, Amsterdam Institute for Infection and Immunity, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, The Netherlands. Electronic address:

Background: Proteasome-associated autoinflammatory syndromes (PRAASs) form a family of recently described rare autosomal recessive disorders of disturbed proteasome assembly and proteolytic activity caused by mutations in genes coding for proteasome subunits. The treatment options for these proteasome disorders consist of lifelong immunosuppressive drugs or Janus kinase inhibitors, which may have partial efficacy and noticeable side effects. Because proteasomes are ubiquitously expressed, it is unknown whether hematopoietic stem cell transplantation (HSCT) may be a sufficient treatment option.

Objective: Our aim was to report the case of a young boy with a treatment-resistant cutaneous vasculitis that was initially suspected to be associated with a gene variant in SH2D1A.

Methods: Whole-exome sequencing was performed to identify the genetic defect. Molecular and functional analyses were performed to assess the impact of variants on proteasomal function. The immune characterization led to the decision to perform HSCT on our patient and conduct follow-up over the 7-year period after the transplant. Because loss of myeloid chimerism after the first HSCT was associated with relapse of autoinflammation, a second HSCT was performed.

Results: After the successful second HSCT, the patient developed mild symptoms of lipodystrophy, which raised the suspicion of a PRAAS. Genetic analysis revealed 2 novel heterozygous variants in PSMB4 (encoding proteasomal subunit β7). Retrospective analysis of patient cells stored before the first HSCT and patient cells obtained after the second HSCT demonstrated that HSCT successfully rescued proteasome function, restored protein homeostasis, and resolved the interferon-stimulated gene signature. Furthermore, successful HSCT alleviated the autoinflammatory manifestations in our patient.

Conclusion: Patients with treatment-resistant PRAAS can be cured by HSCT.
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http://dx.doi.org/10.1016/j.jaci.2021.07.039DOI Listing
August 2021

Activated neutrophils exert myeloid-derived suppressor cell activity damaging T cells beyond repair.

Blood Adv 2019 11;3(22):3562-3574

Department of Blood Cell Research, Sanquin Research, Amsterdam University Medical Center (AUMC), University of Amsterdam, Amsterdam, The Netherlands.

Myeloid-derived suppressor cells (MDSCs) have the capacity to suppress T-cell-mediated immune responses and impact the clinical outcome of cancer, infections, and transplantation settings. Although MDSCs were initially described as bone marrow-derived immature myeloid cells (either monocytic or granulocytic MDSCs), mature neutrophils have been shown to exert MDSC activity toward T cells in ways that remain unclear. In this study, we demonstrated that human neutrophils from both healthy donors and cancer patients do not exert MDSC activity unless they are activated. By using neutrophils with genetically well-defined defects, we found that reactive oxygen species (ROS) and granule-derived constituents are required for MDSC activity after direct CD11b-dependent interactions between neutrophils and T cells. In addition to these cellular interactions, neutrophils are engaged in the uptake of pieces of T-cell membrane, a process called trogocytosis. Together, these interactions led to changes in T-cell morphology, mitochondrial dysfunction, and adenosine triphosphate depletion, as indicated by electron microscopy, mass spectrometry, and metabolic parameters. Our studies characterize the different steps by which activated mature neutrophils induce functional T-cell nonresponsiveness and irreparable cell damage.
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http://dx.doi.org/10.1182/bloodadvances.2019031609DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6880908PMC
November 2019

High-throughput compound screen reveals mTOR inhibitors as potential therapeutics to reduce (auto)antibody production by human plasma cells.

Eur J Immunol 2020 01 14;50(1):73-85. Epub 2019 Nov 14.

Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, Department of Pediatric Immunology, Rheumatology and Infectious diseases, Amsterdam, The Netherlands.

Antibody production by the B cell compartment is a crucial part of the adaptive immune response. Dysregulated antibody production in the form of autoantibodies can cause autoimmune disease. To date, B-cell depletion with anti-CD20 antibodies is commonly applied in autoimmunity, but pre-existing plasma cells are not eliminated in this way. Alternative ways of more selective inhibition of antibody production would add to the treatment of these autoimmune diseases. To explore novel therapeutic targets in signaling pathways essential for plasmablast formation and/or immunoglobulin production, we performed a compound screen of almost 200 protein kinase inhibitors in a robust B-cell differentiation culture system. This study yielded 35 small cell-permeable compounds with a reproducible inhibitory effect on B-cell activation and plasmablast formation, among which was the clinically applied mammalian target of rapamycin (mTOR) inhibitor rapamycin. Two additional compounds targeting the phosphoinositide 3-kinase-AKT-mTOR pathway (BKM120 and WYE-354) did not affect proliferation and plasmablast formation, but specifically reduced the immunoglobulin production. With this compound screen we successfully applied a method to investigate therapeutic targets for B-cell differentiation and identified compounds in the phosphoinositide 3-kinase-AKT-mTOR pathway that could specifically inhibit immunoglobulin production only. These drugs may well be explored to be of value in current B-cell-depleting treatment regimens in autoimmune disorders.
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http://dx.doi.org/10.1002/eji.201948241DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6972998PMC
January 2020

Neutrophils acquire antigen-presenting cell features after phagocytosis of IgG-opsonized erythrocytes.

Blood Adv 2019 06;3(11):1761-1773

Department of Blood Cell Research, Sanquin Research and Landsteiner Laboratory, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.

Neutrophils are particularly well known for their antimicrobial function. Although historically they are regarded as strictly a phagocyte of the innate immune system, over time it has become clear that neutrophils are versatile cells with numerous functions including innate and adaptive immune regulation. We have previously described a role for human neutrophils in antibody-mediated red blood cell (RBC) clearance. Under homeostatic conditions, neutrophils do not take up RBCs. Yet, when RBCs are immunoglobulin G (IgG) opsonized, which can occur in alloimmunization or autoimmunization reactions, neutrophils can effectively phagocytose RBCs. In the present study, we show that human neutrophils acquire an antigen-presenting cell (APC) phenotype following RBC phagocytosis. Subsequent to RBC phagocytosis, neutrophils expressed major histocompatibility complex class II (MHC-II) and costimulatory molecules such as CD40 and CD80. Moreover, in classical APCs, the respiratory burst is known to regulate antigen presentation. We found that the respiratory burst in neutrophils is reduced after IgG-mediated RBC phagocytosis. Additionally, following RBC phagocytosis, neutrophils were demonstrated to elicit an antigen-specific T-cell response, using tetanus toxoid (TT) as an antigen to elicit an autologous TT-specific CD4 T-cell response. Lastly, although the "don't eat me" signal CD47 is known to have a powerful restrictive role in the activation of immunity against RBCs in dendritic cells, CD47 does not seem to have a significant effect on the antigen-presenting function of neutrophils in this context. Overall, these findings reveal that besides their classical antimicrobial role, neutrophils show plasticity in their phenotype.
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http://dx.doi.org/10.1182/bloodadvances.2018028753DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6560339PMC
June 2019

Pathogenic NFKB2 variant in the ankyrin repeat domain (R635X) causes a variable antibody deficiency.

Clin Immunol 2019 06 3;203:23-27. Epub 2019 Apr 3.

Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, Department of Pediatric Immunology, Rheumatology and Infectious diseases, Meibergdreef 9, Amsterdam, The Netherlands; Amsterdam UMC, University of Amsterdam, Department of Experimental Immunology, Amsterdam Infection & Immunity Institute, Meibergdreef 9, Amsterdam, The Netherlands. Electronic address:

Genetic studies are identifying an increasing number of monogenic causes of Common Variable Immunodeficiency (CVID). Pathogenic variants in the C-terminus of NFKB2 have been identified in the subset of CVID patients whose immunodeficiency is associated with ectodermal dysplasia and central adrenal insufficiency. We describe 2 unrelated CVID pedigrees with 4 cases of pathogenic stop gain variants (c.1903C > T) in the ankyrin repeat domain (ARD) of NF-κB2, leading to a premature truncation of the protein at p.Arg635Term (R635X). By immunophenotyping and functional ex vivo B- and T-cell experiments we characterized the variant by reduced class-switched memory B-cell counts and immature plasmablasts, unable to produce IgG and IgA. Features of a poor proliferative T-cell response and reduced expansion of CD4CXCR5 T cells was only observed in the two clinically affected index cases without any clear clinical correlate. In conclusion, pathogenic stop variants in the ARD of NFKB2 can cause 'infection-only' CVID with an abnormal B-cell phenotype and a variable clinical penetrance.
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http://dx.doi.org/10.1016/j.clim.2019.03.010DOI Listing
June 2019

Loss-of-function nuclear factor κB subunit 1 (NFKB1) variants are the most common monogenic cause of common variable immunodeficiency in Europeans.

J Allergy Clin Immunol 2018 10 2;142(4):1285-1296. Epub 2018 Mar 2.

Department of Pediatric Hematology, Immunology and Infectious Diseases, Emma Children's Hospital, Academic Medical Center, Amsterdam, The Netherlands; Department of Experimental Immunology, Academic Medical Center, Amsterdam, The Netherlands; Department of Internal Medicine, Academic Medical Center, Amsterdam, The Netherlands. Electronic address:

Background: The genetic cause of primary immunodeficiency disease (PID) carries prognostic information.

Objective: We conducted a whole-genome sequencing study assessing a large proportion of the NIHR BioResource-Rare Diseases cohort.

Methods: In the predominantly European study population of principally sporadic unrelated PID cases (n = 846), a novel Bayesian method identified nuclear factor κB subunit 1 (NFKB1) as one of the genes most strongly associated with PID, and the association was explained by 16 novel heterozygous truncating, missense, and gene deletion variants. This accounted for 4% of common variable immunodeficiency (CVID) cases (n = 390) in the cohort. Amino acid substitutions predicted to be pathogenic were assessed by means of analysis of structural protein data. Immunophenotyping, immunoblotting, and ex vivo stimulation of lymphocytes determined the functional effects of these variants. Detailed clinical and pedigree information was collected for genotype-phenotype cosegregation analyses.

Results: Both sporadic and familial cases demonstrated evidence of the noninfective complications of CVID, including massive lymphadenopathy (24%), unexplained splenomegaly (48%), and autoimmune disease (48%), features prior studies correlated with worse clinical prognosis. Although partial penetrance of clinical symptoms was noted in certain pedigrees, all carriers have a deficiency in B-lymphocyte differentiation. Detailed assessment of B-lymphocyte numbers, phenotype, and function identifies the presence of an increased CD21 B-cell population. Combined with identification of the disease-causing variant, this distinguishes between healthy subjects, asymptomatic carriers, and clinically affected cases.

Conclusion: We show that heterozygous loss-of-function variants in NFKB1 are the most common known monogenic cause of CVID, which results in a temporally progressive defect in the formation of immunoglobulin-producing B cells.
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http://dx.doi.org/10.1016/j.jaci.2018.01.039DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6148345PMC
October 2018

Humoral Immunodeficiency with Hypotonia, Feeding Difficulties, Enteropathy, and Mild Eczema Caused by a Classical Mutation.

Front Pediatr 2017 27;5:37. Epub 2017 Feb 27.

Department of Pediatric Hematology, Immunology, Rheumatology and Infectious Diseases, Emma Children's Hospital, Academic Medical Center (AMC), University of Amsterdam, Amsterdam, Netherlands; Department of Clinical Genetics, Academic Medical Center (AMC), University of Amsterdam, Amsterdam, Netherlands.

We describe here the case of a boy who presented with pulmonary infections, feeding difficulties due to velopharyngeal insufficiency and gastroesophageal reflux, myopathy, and hypotonia soon after birth. Later, he was also found to have an elevated immunoglobulin (Ig) E and mild eczema and was diagnosed with inflammatory bowel disease. Further immunological screening at the age of 7 years showed low B and NK cell numbers but normal CD4 and CD8 T cells and notably, normal numbers of CD4 regulatory T (Treg) cells. Serum IgG, IgA, and IgM were low to normal, but he had a deficient response to a pneumococcal polysaccharide vaccine and thus a humoral immunodeficiency. To our surprise, whole exome sequencing revealed a mutation in , encoding an essential transcription factor for the development and function of Treg cells. This classical mutation is associated with immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome. Further studies indeed showed defective function of Treg cells despite normal FOXP3 protein expression and nuclear localization. The boy underwent hematopoietic stem cell transplantation at 11 years of age and despite the temporary development of diabetes while on prednisone is now doing much better, IgE levels have declined, and his fatigue has improved. This case illustrates that a classical pathogenic mutation in can lead to a clinical phenotype where the diagnosis of IPEX syndrome was never considered because of the lack of diabetes and the presence of only mild eczema, in addition to the normal Treg cell numbers and FOXP3 expression.
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http://dx.doi.org/10.3389/fped.2017.00037DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5326763PMC
February 2017

Mutations in EXTL3 Cause Neuro-immuno-skeletal Dysplasia Syndrome.

Am J Hum Genet 2017 02 26;100(2):281-296. Epub 2017 Jan 26.

Emerita, Department of Radiology, Great Ormond Street Hospital, WC1N 3JH London, UK.

EXTL3 regulates the biosynthesis of heparan sulfate (HS), important for both skeletal development and hematopoiesis, through the formation of HS proteoglycans (HSPGs). By whole-exome sequencing, we identified homozygous missense mutations c.1382C>T, c.1537C>T, c.1970A>G, and c.2008T>G in EXTL3 in nine affected individuals from five unrelated families. Notably, we found the identical homozygous missense mutation c.1382C>T (p.Pro461Leu) in four affected individuals from two unrelated families. Affected individuals presented with variable skeletal abnormalities and neurodevelopmental defects. Severe combined immunodeficiency (SCID) with a complete absence of T cells was observed in three families. EXTL3 was most abundant in hematopoietic stem cells and early progenitor T cells, which is in line with a SCID phenotype at the level of early T cell development in the thymus. To provide further support for the hypothesis that mutations in EXTL3 cause a neuro-immuno-skeletal dysplasia syndrome, and to gain insight into the pathogenesis of the disorder, we analyzed the localization of EXTL3 in fibroblasts derived from affected individuals and determined glycosaminoglycan concentrations in these cells as well as in urine and blood. We observed abnormal glycosaminoglycan concentrations and increased concentrations of the non-sulfated chondroitin disaccharide D0a0 and the disaccharide D0a4 in serum and urine of all analyzed affected individuals. In summary, we show that biallelic mutations in EXTL3 disturb glycosaminoglycan synthesis and thus lead to a recognizable syndrome characterized by variable expression of skeletal, neurological, and immunological abnormalities.
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http://dx.doi.org/10.1016/j.ajhg.2017.01.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5294674PMC
February 2017

Phenotypic and Functional Comparison of Class Switch Recombination Deficiencies with a Subgroup of Common Variable Immunodeficiencies.

J Clin Immunol 2016 10 2;36(7):656-66. Epub 2016 Aug 2.

Department of Pediatric Hematology, Immunology and Infectious Diseases, Academic Medical Center (AMC), Amsterdam, The Netherlands.

Primary antibody deficiencies (PADs) are the most common immunodeficiency in humans, characterized by low levels of immunoglobulins and inadequate antibody responses upon immunization. These PADs may result from an early block in B cell development with a complete absence of peripheral B cells and lack of immunoglobulins. In the presence of circulating B cells, some PADs are genetically caused by a class switch recombination (CSR) defect, but in the most common PAD, common variable immunodeficiency (CVID), very few gene defects have as yet been characterized despite various phenotypic classifications. Using a functional read-out, we previously identified a functional subgroup of CVID patients with plasmablasts (PBs) producing IgM only. We have now further characterized such CVID patients by a direct functional comparison with patients having genetically well-characterized CSR defects in CD40L, activation-induced cytidine deaminase (AID) and uracil N-glycosylase activity (UNG). The CSR-like CVID patients showed a failure in B cell activation patterns similar to the classical AID/UNG defects in three out of five CVID patients and distinct more individual defects in the two other CVID cases when tested for cellular activation and PB differentiation. Thus, functional categorization of B cell activation and differentiation pathways extends the expected variation in CVID to CSR-like defects of as yet unknown genetic etiology.
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http://dx.doi.org/10.1007/s10875-016-0321-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5018261PMC
October 2016

Varicella vaccination in pediatric oncology patients without interruption of chemotherapy.

J Clin Virol 2016 Feb 7;75:47-52. Epub 2016 Jan 7.

Department of Pediatric Hematology, Immunology and Infectious Diseases, Emma Children's Hospital, Academic Medical Center, Amsterdam, The Netherlands. Electronic address:

Background: Morbidity and mortality from primary varicella-zoster virus (VZV) infection is increased in immunocompromised children. Vaccination of VZV-seronegative cancer patients with live-attenuated varicella vaccine is safe when chemotherapy is interrupted. However, VZV vaccination without interruption of chemotherapy would be preferable.

Objective: To vaccinate VZV-seronegative pediatric oncology patients with live-attenuated VZV vaccine without interrupting their chemotherapy.

Study-design: We performed a single-center prospective cohort study.

Results: Thirty-one patients with either a hematological malignancy (n=24) or a solid tumor (n=7) were vaccinated early during their course of chemotherapy. VZV IgG seroconversion occurred in 14 of the 31 patients (45%) after one vaccination. Only 20 patients were revaccinated after 3 months. These were patients who did not seroconvert (5 patients) and patients who serocoverted (15 patients) to induce or sustain seropositivity. Of these 20 patients the final seroconversion rate was 70%. Seven out of the 31 patients (23%) developed a mild rash of which 5 were treated with antivirals and recovered completely without interrupting chemotherapy, and 2 recovered untreated. Of these 31 immunized patients 26 were available for cellular testing. After one vaccination 20 of 26 patients (77%) tested positive for VZV-specific CD4(+) T cells, of which 7 patients had remained VZV-seronegative. After the second vaccination 11 of 11 patients showed VZV-specific CD4(+) T cells to sustain positivity, although 4 remained VZV-seronegative.

Conclusions: This study indicates that live-attenuated VZV vaccine can be safely administered to closely monitored pediatric oncology patients without interruption of chemotherapy and adaptive immunity was induced despite incomplete seroconversion.
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http://dx.doi.org/10.1016/j.jcv.2016.01.004DOI Listing
February 2016

ADAR1 Facilitates HIV-1 Replication in Primary CD4+ T Cells.

PLoS One 2015 2;10(12):e0143613. Epub 2015 Dec 2.

Department of Experimental Immunology, Academic Medical Center (AMC), University of Amsterdam (UvA), Amsterdam, The Netherlands.

Unlike resting CD4+ T cells, activated CD4+T cells are highly susceptible to infection of human immunodeficiency virus 1 (HIV-1). HIV-1 infects T cells and macrophages without activating the nucleic acid sensors and the anti-viral type I interferon response. Adenosine deaminase acting on RNA 1 (ADAR1) is an RNA editing enzyme that displays antiviral activity against several RNA viruses. Mutations in ADAR1 cause the autoimmune disorder Aicardi-Goutieères syndrome (AGS). This disease is characterized by an inappropriate activation of the interferon-stimulated gene response. Here we show that HIV-1 replication, in ADAR1-deficient CD4+T lymphocytes from AGS patients, is blocked at the level of protein translation. Furthermore, viral protein synthesis block is accompanied by an activation of interferon-stimulated genes. RNA silencing of ADAR1 in Jurkat cells also inhibited HIV-1 protein synthesis. Our data support that HIV-1 requires ADAR1 for efficient replication in human CD4+T cells.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0143613PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4667845PMC
June 2016

Phenotypic variation in Aicardi-Goutières syndrome explained by cell-specific IFN-stimulated gene response and cytokine release.

J Immunol 2015 Apr 13;194(8):3623-33. Epub 2015 Mar 13.

Department of Astrocyte Biology and Neurodegeneration, Netherlands Institute for Neuroscience, Institute of the Royal Netherlands Academy of Arts and Sciences, 1105 BA Amsterdam, the Netherlands; Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, 3584 CG Utrecht, the Netherlands; Center for Neuroscience, Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH Amsterdam, the Netherlands.

Aicardi-Goutières syndrome (AGS) is a monogenic inflammatory encephalopathy caused by mutations in TREX1, RNASEH2A, RNASEH2B, RNASEH2C, SAMHD1, ADAR1, or MDA5. Mutations in those genes affect normal RNA/DNA intracellular metabolism and detection, triggering an autoimmune response with an increase in cerebral IFN-α production by astrocytes. Microangiopathy and vascular disease also contribute to the neuropathology in AGS. In this study, we report that AGS gene silencing of TREX1, SAMHD1, RNASEH2A, and ADAR1 by short hairpin RNAs in human neural stem cell-derived astrocytes, human primary astrocytes, and brain-derived endothelial cells leads to an antiviral status of these cells compared with nontarget short hairpin RNA-treated cells. We observed a distinct activation of the IFN-stimulated gene signature with a substantial increase in the release of proinflammatory cytokines (IL-6) and chemokines (CXCL10 and CCL5). A differential impact of AGS gene silencing was noted; silencing TREX1 gave rise to the most dramatic in both cell types. Our findings fit well with the observation that patients carrying mutations in TREX1 experience an earlier onset and fatal outcome. We provide in the present study, to our knowledge for the first time, insight into how astrocytic and endothelial activation of antiviral status may differentially lead to cerebral pathology, suggesting a rational link between proinflammatory mediators and disease severity in AGS.
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http://dx.doi.org/10.4049/jimmunol.1401334DOI Listing
April 2015

Fetal exposure to HIV-1 alters chemokine receptor expression by CD4+T cells and increases susceptibility to HIV-1.

Sci Rep 2014 Oct 24;4:6690. Epub 2014 Oct 24.

1] Department of Pediatric Hematology, Immunology and Infectious Diseases, Emma Children's Hospital, Academic Medical Centre (AMC), University of Amsterdam (UvA), Amsterdam, The Netherlands [2] Department of Experimental Immunology, AMC, UvA, Amsterdam, The Netherlands.

Absolute numbers of lymphocytes are decreased in uninfected infants born to HIV-1-infected women (HIV-1-exposed). Although the exact mechanism is unknown, fetal exposure to maternal HIV-1-infection could prime the immune system and affect T cell trafficking. We compared the expression of chemokine receptors on cord blood CD4(+) T cells from HIV-1-exposed children and healthy controls. At baseline CD4(+) T cells had a largely naïve phenotype. However, stimulation with cytokines resulted in an upregulation of inflammatory response-related chemokine receptors on CD4(+) T cells, with HIV-1-exposed infants having a significantly higher frequency of CD4(+) T cells expressing, in particularly Th2 associated chemokine receptors (CCR3 p < 0.01, CCR8 p = 0.03). Numbers of naive CCR7(+) CD4(+) T cells were reduced (p = 0.01) in HIV-1-exposed infants. We further assessed whether the inflammatory phenotype was associated with susceptibility to HIV-1 and detected higher levels of p24 upon in in vitro infection of stimulated CD4(+) T cells of HIV-1-exposed infants. In summary, fetal exposure to HIV-1 primes the immune system in the infant leading to an enhanced immune activation and altered T cell homing, with potential ramifications regarding T cell responses and the acquisition of HIV-1 as an infant.
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http://dx.doi.org/10.1038/srep06690DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4208038PMC
October 2014

Aicardi-Goutières syndrome harbours abundant systemic and brain-reactive autoantibodies.

Ann Rheum Dis 2015 Oct 6;74(10):1931-9. Epub 2014 Jun 6.

Department of Experimental Immunology, Academic Medical Center, University of Amsterdam (UvA), Amsterdam, The Netherlands.

Objectives: Aicardi-Goutières syndrome (AGS) is an autoimmune disorder that shares similarities with systemic lupus erythematous. AGS inflammatory responses specially target the cerebral white matter. However, it remains uncertain why the brain is the most affected organ, and little is known about the presence of autoantibodies in AGS. Here, we aim to profile specific autoantibodies in AGS and to determine whether these autoantibodies target cerebral epitopes.

Methods: Using a multiplex microarray, we assessed the spectrum of serum autoantibodies in 56 genetically confirmed patients with AGS. We investigated the presence of immunoglobulins in AGS brain specimens using immunohistochemistry and studied the reactivity of sera against brain epitopes with proteomics.

Results: Serum from patients exhibited high levels of IgGs against nuclear antigens (gP210, Nup62, PCNA, Ro/SSA, Sm/RNP complex, SS-A/SS-B), components of the basement membrane (entactin, laminin), fibrinogen IV and gliadin. Upon testing whether antibodies in AGS could be found in the central nervous system, IgGs were identified to target in vivo endothelial cells in vivo and astrocytes in brain sections of deceased patients with AGS. Using a proteomics approach, we were able to confirm that IgGs in serum samples from AGS patients bind epitopes present in the cerebral white matter.

Conclusions: Patients with AGS produce a broad spectrum of autoantibodies unique from other autoimmune diseases. Some of these autoantibodies target endothelial cells and astrocytes in the brain of the affected patients, perhaps explaining the prominence of neurological disease in the AGS phenotype.
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http://dx.doi.org/10.1136/annrheumdis-2014-205396DOI Listing
October 2015

Aberrant humoral immune reactivity in DOCK8 deficiency with follicular hyperplasia and nodal plasmacytosis.

Clin Immunol 2013 Oct 19;149(1):25-31. Epub 2013 Jun 19.

Department of Experimental Immunology, Academic Medical Center (AMC), Amsterdam, The Netherlands; Emma Children's Hospital, AMC, Amsterdam, The Netherlands. Electronic address:

Mutations in the DOCK8 gene define the most common form of autosomal-recessive Hyper-IgE-syndrome (AR-HIES/OMIM#243700). In a patient with extensive molluscum contagiosum lesions, a homozygous DOCK8 gene deletion was demonstrated. In-vivo 18-FDG uptake showed multiple non-enlarged lymph nodes without uptake in the spleen. Lymph node biopsies for subsequent immunohistochemistry showed clear differences with the mouse model of DOCK8 deficiency in which these mice show no GCs. Unexpectedly, the patient's lymph nodes demonstrated lymphocyte polyclonality, follicular hyperplasia and an unusual IgE(+) plasma cell expansion. In contrast, the proliferative capacity of circulating B-cells was almost absent with little in-vitro Ig production or plasmablast formation. Also the T-cell proliferation indicated a partial defect. Hematopoietic stem cell transplantation (HSCT) was performed resulting in the disappearance of the molluscum contagiosum lesions. In sum, DOCK8 deficiency results in defective antibody responses and undirected plasma cell expansion in the lymph nodes, as part of a combined immunodeficiency cured by HSCT.
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http://dx.doi.org/10.1016/j.clim.2013.06.002DOI Listing
October 2013

Identification of B cell defects using age-defined reference ranges for in vivo and in vitro B cell differentiation.

J Immunol 2013 May 12;190(10):5012-9. Epub 2013 Apr 12.

Department of Pediatric Hematology, Immunology, and Infectious Diseases, Emma Children's Hospital, Academic Medical Center, 1105 AZ Amsterdam, The Netherlands.

Primary immunodeficiencies consist to a large extent of B cell defects, as indicated by inadequate Ab levels or response upon immunization. Many B cell defects have not yet been well characterized. Our objective was to create reliable in vivo and in vitro assays to routinely analyze human B cell differentiation, proliferation, and Ig production and to define reference ranges for different age categories. The in vitro assays were applied to classify the developmental and/or functional B cell defects in patients previously diagnosed with common variable immunodeficiency. Apart from standard immunophenotyping of circulating human B cell subsets, an in vitro CFSE dilution assay was used for the assessment of proliferative capacity comparing T cell-dependent and T cell-independent B cell activation. Plasmablast/plasma cell differentiation was assessed by staining for CD20, CD38, and CD138, and measurement of in vitro Ig secretion. At young age, B cells proliferate upon in vitro activation, but neither differentiate nor produce IgG. These latter functions reached adult levels at 5 and 10 y of age for T cell-dependent versus T cell-independent stimulations, respectively. The capacity of B cells to differentiate into plasmablasts and to produce IgG appeared to be contained within the switched memory B cell pool. Using these assays, we could categorize common variable immunodeficiency patients into subgroups and identified a class-switch recombination defect caused by an UNG mutation in one of the patients. We defined age-related reference ranges for human B cell differentiation. Our findings indicate that in vivo B cell functionality can be tested in vitro and helps to diagnose suspected B cell defects.
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http://dx.doi.org/10.4049/jimmunol.1201807DOI Listing
May 2013

A reversion of an IL2RG mutation in combined immunodeficiency providing competitive advantage to the majority of CD8+ T cells.

Haematologica 2013 Jul 12;98(7):1030-8. Epub 2013 Feb 12.

Emma Children's Hospital, Academic Medical Center (AMC), Amsterdam, The Netherlands.

Mutations in the common gamma chain (γc, CD132, encoded by the IL2RG gene) can lead to B(+)T(-)NK(-) X-linked severe combined immunodeficiency, as a consequence of unresponsiveness to γc-cytokines such as interleukins-2, -7 and -15. Hypomorphic mutations in CD132 may cause combined immunodeficiencies with a variety of clinical presentations. We analyzed peripheral blood mononuclear cells of a 6-year-old boy with normal lymphocyte counts, who suffered from recurrent pneumonia and disseminated mollusca contagiosa. Since proliferative responses of T cells and NK cells to γc -cytokines were severely impaired, we performed IL2RG gene analysis, showing a heterozygous mutation in the presence of a single X-chromosome. Interestingly, an IL2RG reversion to normal predominated in both naïve and antigen-primed CD8(+) T cells and increased over time. Only the revertant CD8(+) T cells showed normal expression of CD132 and the various CD8(+) T cell populations had a different T-cell receptor repertoire. Finally, a fraction of γδ(+) T cells and differentiated CD4(+)CD27(-) effector-memory T cells carried the reversion, whereas NK or B cells were repeatedly negative. In conclusion, in a patient with a novel IL2RG mutation, gene-reverted CD8(+) T cells accumulated over time. Our data indicate that selective outgrowth of particular T-cell subsets may occur following reversion at the level of committed T progenitor cells.
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http://dx.doi.org/10.3324/haematol.2012.077511DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3696605PMC
July 2013

Chronic exposure of astrocytes to interferon-α reveals molecular changes related to Aicardi-Goutieres syndrome.

Brain 2013 Jan;136(Pt 1):245-58

Department of Astrocyte Biology and Neurodegeneration, Netherlands Institute for Neuroscience–an Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands.

Aicardi-Goutières syndrome is a genetically determined infantile encephalopathy, manifesting as progressive microcephaly, psychomotor retardation, and in ∼25% of patients, death in early childhood. Aicardi-Goutières syndrome is caused by mutations in any of the genes encoding TREX1, RNASEH2-A, -B, -C and SAMHD1, with protein dysfunction hypothesized to result in the accumulation of nucleic acids within the cell, thus triggering an autoinflammatory response with increased interferon-α production. Astrocytes have been identified as a major source of interferon-α production in the brains of patients with Aicardi-Goutières syndrome. Here, we study the effect of interferon-α treatment on astrocytes derived from immortalized human neural stem cells. Chronic interferon-α treatment promoted astrocyte activation and a reduction in cell proliferation. Moreover, chronic exposure resulted in an alteration of genes and proteins involved in the stability of white matter (ATF4, eIF2Bα, cathepsin D, cystatin F), an increase of antigen-presenting genes (human leukocyte antigen class I) and downregulation of pro-angiogenic factors and other cytokines (vascular endothelial growth factor and IL-1). Interestingly, withdrawal of interferon-α for 7 days barely reversed these cellular alterations, demonstrating that the interferon-α mediated effects persist over time. We confirmed our in vitro findings using brain samples from patients with Aicardi-Goutières syndrome. Our results support the idea of interferon-α as a key factor in the pathogenesis of Aicardi-Goutières syndrome relating to the observed leukodystrophy and microangiopathy. Because of the sustained interferon-α effect, even after withdrawal, therapeutic targets for Aicardi-Goutières syndrome, and other interferon-α-mediated encephalopathies, may include downstream interferon-α signalling cascade effectors rather than interferon-α alone.
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http://dx.doi.org/10.1093/brain/aws321DOI Listing
January 2013

Invasive fungal infection and impaired neutrophil killing in human CARD9 deficiency.

Blood 2013 Mar 18;121(13):2385-92. Epub 2013 Jan 18.

Sanquin Research, and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.

Caspase recruitment domain-containing protein 9 (CARD9) is an adaptor molecule in the cytosol of myeloid cells, required for induction of T-helper cells producing interleukin-17 (Th17 cells) and important in antifungal immunity. In a patient suffering from Candida dubliniensis meningoencephalitis, mutations in the CARD9 gene were found to result in the loss of protein expression. Apart from the reduced numbers of CD4(+) Th17 lymphocytes, we identified a lack of monocyte-derived cytokines in response to Candida strains. Importantly, CARD9-deficient neutrophils showed a selective Candida albicans killing defect with abnormal ultrastructural phagolysosomes and outgrowth of hyphae. The neutrophil killing defect was independent of the generation of reactive oxygen species by the reduced NAD phosphate oxidase system. Taken together, this demonstrates that human CARD9 deficiency results in selective defect in the host defense against invasive fungal infection, caused by an impaired phagocyte killing.
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http://dx.doi.org/10.1182/blood-2012-08-450551DOI Listing
March 2013

Idiopathic CD4+ T lymphopenia without autoimmunity or granulomatous disease in the slipstream of RAG mutations.

Blood 2011 Jun 18;117(22):5892-6. Epub 2011 Apr 18.

Emma Children's Hospital, Academic Medical Center, Meibergdreef 9, Amsterdam, The Netherlands.

A girl presented during childhood with a single course of extensive chickenpox and moderate albeit recurrent pneumonia in the presence of idiopathic CD4+ T lymphocytopenia (ICL). Her clinical condition remained stable over the past 10 years without infections, any granulomatous disease, or autoimmunity. Immunophenotyping demonstrated strongly reduced naive T and B cells with intact proliferative capacity. Antibody reactivity on in vivo immunizations was normal. T-cell receptor-Vβ repertoire was polyclonal with a very low content of T-cell receptor excision circles (TRECs). Kappa-deleting recombination excision circles (KRECs) were also abnormal in the B cells. Both reflect extensive in vivo proliferation. Patient-derived CD34+ hematopoietic stem cells could not repopulate RAG2(-/-)IL2Rγc(-/-) mice, indicating the lymphoid origin of the defect. We identified 2 novel missense mutations in RAG1 (p.Arg474Cys and p.Leu506Phe) resulting in reduced RAG activity. This report gives the first genetic clue for ICL and extends the clinical spectrum of RAG mutations from severe immune defects to an almost normal condition.
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http://dx.doi.org/10.1182/blood-2011-01-329052DOI Listing
June 2011
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