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  • 1
    Publication Date: 2013-10-19
    Description: Genetic mutations cause primary immunodeficiencies (PIDs) that predispose to infections. Here, we describe activated PI3K-delta syndrome (APDS), a PID associated with a dominant gain-of-function mutation in which lysine replaced glutamic acid at residue 1021 (E1021K) in the p110delta protein, the catalytic subunit of phosphoinositide 3-kinase delta (PI3Kdelta), encoded by the PIK3CD gene. We found E1021K in 17 patients from seven unrelated families, but not among 3346 healthy subjects. APDS was characterized by recurrent respiratory infections, progressive airway damage, lymphopenia, increased circulating transitional B cells, increased immunoglobulin M, and reduced immunoglobulin G2 levels in serum and impaired vaccine responses. The E1021K mutation enhanced membrane association and kinase activity of p110delta. Patient-derived lymphocytes had increased levels of phosphatidylinositol 3,4,5-trisphosphate and phosphorylated AKT protein and were prone to activation-induced cell death. Selective p110delta inhibitors IC87114 and GS-1101 reduced the activity of the mutant enzyme in vitro, which suggested a therapeutic approach for patients with APDS.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3930011/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3930011/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Angulo, Ivan -- Vadas, Oscar -- Garcon, Fabien -- Banham-Hall, Edward -- Plagnol, Vincent -- Leahy, Timothy R -- Baxendale, Helen -- Coulter, Tanya -- Curtis, James -- Wu, Changxin -- Blake-Palmer, Katherine -- Perisic, Olga -- Smyth, Deborah -- Maes, Mailis -- Fiddler, Christine -- Juss, Jatinder -- Cilliers, Deirdre -- Markelj, Gasper -- Chandra, Anita -- Farmer, George -- Kielkowska, Anna -- Clark, Jonathan -- Kracker, Sven -- Debre, Marianne -- Picard, Capucine -- Pellier, Isabelle -- Jabado, Nada -- Morris, James A -- Barcenas-Morales, Gabriela -- Fischer, Alain -- Stephens, Len -- Hawkins, Phillip -- Barrett, Jeffrey C -- Abinun, Mario -- Clatworthy, Menna -- Durandy, Anne -- Doffinger, Rainer -- Chilvers, Edwin R -- Cant, Andrew J -- Kumararatne, Dinakantha -- Okkenhaug, Klaus -- Williams, Roger L -- Condliffe, Alison -- Nejentsev, Sergey -- 095198/Wellcome Trust/United Kingdom -- 095198/Z/10/Z/Wellcome Trust/United Kingdom -- 095691/Wellcome Trust/United Kingdom -- BB/J004456/1/Biotechnology and Biological Sciences Research Council/United Kingdom -- MC_U105184308/Medical Research Council/United Kingdom -- U105184308/Medical Research Council/United Kingdom -- New York, N.Y. -- Science. 2013 Nov 15;342(6160):866-71. doi: 10.1126/science.1243292. Epub 2013 Oct 17.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Medicine, University of Cambridge, Cambridge, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24136356" target="_blank"〉PubMed〈/a〉
    Keywords: Class I Phosphatidylinositol 3-Kinases ; *Genetic Predisposition to Disease ; Humans ; Immunologic Deficiency Syndromes/*genetics/immunology/*pathology ; Lymphocytes/immunology ; Mutation ; Pedigree ; Phosphatidylinositol 3-Kinases/*genetics ; Phosphatidylinositol Phosphates/metabolism ; Proto-Oncogene Proteins c-akt/metabolism ; Respiratory Tract Infections/*genetics/immunology/*pathology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Bacteria-specific IgA antibodies are efficient opsonins for neutrophils and mononuclear phagocytes, provided that the phagocytes express the Fca receptor (CD89). Expression of CD89 can be stimulated by inflammatory cytokines, activated complement factors and certain microbial components. In one study, unstimulated phagocytes were able to ingest IgA antibody-treated pneumococci, but only in the presence of complement, which was found to be activated by the IgA antibodies along the alternative pathway. Pneumococci produce IgA1 protease that cleaves human IgA1, but not IgA2, molecules in the hinge region. This leaves IgA1 as Fabα (monovalent) deprived of Fcα which contains the docking site for CD89. IgA1 is the vastly predominant subclass of IgA in the upper airways and circulation of humans.Aims:  To examine the effects of IgA1 protease activity and complement on phagocytosis of IgA antibody-coated pneumococci by an unstimulated human phagocytic cell line (hl60).Materials and methods:  IgA1 and IgA2 monoclonal antibodies to serotype 4 pneumococcal capsular polysaccharide (ps) were generated by heterohybridoma technique involving B cells from human vaccinees. Isogenic serotype 4 pneumococci with and without IgA1 protease activity, respectively, were obtained after inactivation of the iga gene of the TIGR4 strain. Opsonophagocytosis was quantitated using the assay described by Romero-Steiner et al. Based on enumeration of surviving bacteria by culture. The integrity of IgA molecules was examined by western blotting.Results:  Both IgA1 and IgA2 antibody to type-4 polysaccharide-induced phagocytosis of IgA1 protease-deficient type-4 pneumococci equally well in the absence as in the presence of complement. Iga1 antibody to type-4 polysaccharide displayed a fourfold higher opsonophagocytosis titer against IgA1 protease deficient compared to homologous wildtype target bacteria. A similar effect of IgA1 protease activity of the target bacteria was not observed in a parallel experiment where IgA2 antibody to type-4 polysaccharide served as opsonin. IgA1 antibody extracted from IgA1 protease-producing target bacteria was almost exclusively in the form of Fabα. Conversely, IgA1 from protease-deficient bacteria and IgA2 from both types of bacteria were intact.Conclusions:  These results indicate that the IgA1 protease activity of S. neumoniae may help the bacteria escape IgA1 antibody-mediated opsonophagocytosis. Besides, in these experiments, IgA-mediated opsonophagocytosis was independent of complement.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2017-03-17
    Description: Heterozygous CTLA-4 deficiency has been reported as a monogenic cause of common variable immune deficiency with features of immune dysregulation. Direct mutation in CTLA-4 leads to defective regulatory T-cell (Treg) function associated with impaired ability to control levels of the CTLA-4 ligands, CD80 and CD86. However, additional mutations affecting the CTLA-4 pathway, such as those recently reported for LRBA, indirectly affect CTLA-4 expression, resulting in clinically similar disorders. Robust phenotyping approaches sensitive to defects in the CTLA-4 pathway are therefore required to inform understanding of such immune dysregulation syndromes. Here, we describe assays capable of distinguishing a variety of defects in the CTLA-4 pathway. Assessing total CTLA-4 expression levels was found to be optimal when restricting analysis to the CD45RA – Foxp3 + fraction. CTLA-4 induction following stimulation, and the use of lysosomal-blocking compounds, distinguished CTLA-4 from LRBA mutations. Short-term T-cell stimulation improved the capacity for discriminating the Foxp3 + Treg compartment, clearly revealing Treg expansions in these disorders. Finally, we developed a functionally orientated assay to measure ligand uptake by CTLA-4, which is sensitive to ligand-binding or -trafficking mutations, that would otherwise be difficult to detect and that is appropriate for testing novel mutations in CTLA-4 pathway genes. These approaches are likely to be of value in interpreting the functional significance of mutations in the CTLA-4 pathway identified by gene-sequencing approaches.
    Keywords: Immunobiology
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
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