Anaplasma phagocytophilum causes global induction of antiapoptosis in human neutrophils
GENOMICS
Authors: Lee, Hin C.; Goodman, Jesse L.
Abstract
Anoplasma phagocytophilum (Ap), the agent of the tick-borne disease human granulocytic anaplasmosis, is an obligate intracellular pathogen unique in its ability to target and replicate within neutrophils. It profoundly inhibits neutrophil apoptosis, prolonging neutrophil survival from hours to days. To determine the basis of antiapoptosis, we compared gene expression in Ap-infected vs mock-infected human neutrophils. Antiapoptosis genes were consistently and significantly up-regulated (2- to 15-fold) within 1-3 h. These genes synergistically inhibit apoptosis through. several interconnected pathways including p38MAPK (MAP2K3), ERK (IER3), PI3K (PRKCD), and NF-kappa B (BCL2A1, NFKB1, NFKBIA, GADD45B). Both extrinsic death receptor (TNFAIP3, CFLAR, SOD2) and intrinsic mitochondrial:(BCL2A1, PIM2, BIRC3) pathways were affected as confirmed by reductions in both caspase 3 and caspase 8 activities. Several important antiapoptotic genes noted to be up-regulated in Ap-infected neutrophils were not up-regulated during Ap infection of HL-60 cells (which is not antiapoptotic). In conclusion, just as apoptosis may be triggered through multiple molecular pathways, effective antiapoptosis of neutrophils is achieved rapidly and redundantly by this intracellular pathogen dependent on cell survival. Published by Elsevier Inc.
Evaluating the Genetics of Common Variable Immunodeficiency: Monogenetic Model and Beyond
FRONTIERS IN IMMUNOLOGY
Authors: de Valles-Ibanez, Guillem; Esteve-Sole, Ana; Piquer, Monica; Gonzalez-Navarro, E. Azucena; Hernandez-Rodriguez, Jessica; Laayouni, Hafid; Gonzalez-Roca, Eva; Plaza-Martin, Ana Maria; Deya-Martinez, Angela; Martin-Nalda, Andrea; Martinez-Gallo, Monica; Garcia-Prat, Marina; del Pino-Molina, Lucia; Cusco, Ivon; Codina-Sola, Marta; Batlle-Maso, Laura; Solis-Moruno, Manuel; Marques-Bonet, Tomas; Bosch, Elena; Lopez-Granados, Eduardo; Arostegui, Juan Ignacio; Soler-Palacin, Pere; Colobran, Roger; Yague, Jordi; Alsina, Laia; Juan, Manel; Casals, Ferran
Abstract
Common variable immunodeficiency (CVID) is the most frequent symptomatic primary immunodeficiency characterized by recurrent infections, hypogammaglobulinemia and poor response to vaccines. Its diagnosis is made based on clinical and immunological criteria, after exclusion of other diseases that can cause similar phenotypes. Currently, less than 20% of cases of CVID have a known underlying genetic cause. We have analyzed whole-exome sequencing and copy number variants data of 36 children and adolescents diagnosed with CVID and healthy relatives to estimate the proportion of monogenic cases. We have replicated an association of CVID to p.C104R in TNFRSF13B and reported the second case of homozygous patient to date. Our results also identify five causative genetic variants in LRBA, CTLA4, NFKB1, and PIK3R1, as well as other very likely causative variants in PRKCD, MAPK8, or DOCK8 among others. We experimentally validate the effect of the LRBA stop-gain mutation which abolishes protein production and downregulates the expression of CTLA4, and of the frameshift indel in CTLA4 producing expression downregulation of the protein. Our results indicate a monogenic origin of at least 15-24% of the CVID cases included in the study. The proportion of monogenic patients seems to be lower in CVID than in other PID that have also been analyzed by whole exome or targeted gene panels sequencing. Regardless of the exact proportion of CVID monogenic cases, other genetic models have to be considered for CVID. We propose that because of its prevalence and other features as intermediate penetrancies and phenotypic variation within families, CVID could fit with other more complex genetic scenarios. In particular, in this work, we explore the possibility of CVID being originated by an oligogenic model with the presence of heterozygous mutations in interacting proteins or by the accumulation of detrimental variants in particular immunological pathways, as well as perform association tests to detect association with rare genetic functional variation in the CVID cohort compared to healthy controls.