title: Altered intracellular and extracellular signaling leads to impaired T-cell functions in ADA-SCID patients.
abstract: Mutations in the adenosine deaminase (ADA) gene are responsible for a form of severe combined immunodeficiency (SCID) caused by the lymphotoxic accumulation of ADA substrates, adenosine and 2'-deoxy-adenosine. The molecular mechanisms underlying T-cell dysfunction in humans remain to be elucidated. Here, we show that CD4(+) T cells from ADA-SCID patients have severely compromised TCR/CD28-driven proliferation and cytokine production, both at the transcriptional and protein levels. Such an impairment is associated with an intrinsically reduced ZAP-70 phosphorylation, Ca(2+) flux, and ERK1/2 signaling and to defective transcriptional events linked to CREB and NF-kappaB. Moreover, exposure to 2'-deoxy-adenosine results in a stronger inhibition of T-cell activation, mediated by the aberrant A(2A) adenosine receptor signaling engagement and PKA hyperactivation, or in a direct apoptotic effect at higher doses. Conversely, in T cells isolated from patients after gene therapy with retrovirally transduced hematopoietic stem/progenitor cells, the biochemical events after TCR triggering occur properly, leading to restored effector functions and normal sensitivity to apoptosis. Overall, our findings provide a better understanding of the pathogenesis of the immune defects associated with an altered purine metabolism and confirm that ADA gene transfer is an efficacious treatment for ADA-SCID. The trials in this study are enrolled at www.ClinicalTrials.gov as #NCT00598481 and #NCT0059978.
authors.affiliation: San Raffaele Telethon Institute for Gene Therapy, Milan, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Cassani
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Mirolo
authors.forename: Federica
authors.initials: F
authors.lastname: Cattaneo
authors.forename: Ulrike
authors.initials: U
authors.lastname: Benninghoff
authors.forename: Michael
authors.initials: M
authors.lastname: Hershfield
authors.forename: Filippo
authors.initials: F
authors.lastname: Carlucci
authors.forename: Antonella
authors.initials: A
authors.lastname: Tabucchi
authors.forename: Claudio
authors.initials: C
authors.lastname: Bordignon
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Roncarolo
authors.forename: Alessandro
authors.initials: A
authors.lastname: Aiuti
mesh_terms: D000243:Adenosine Deaminase / Q000172:deficiency / Q000235:genetics; D017209:Apoptosis; D015496:CD4-Positive T-Lymphocytes / Q000201:enzymology / Q000276:immunology / Q000378:metabolism* / Q000473:pathology*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D003839:Deoxyadenosines / Q000378:metabolism; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism*; D005786:Gene Expression Regulation; D015316:Genetic Therapy; D006801:Humans; D042541:Intracellular Space / Q000378:metabolism*; D008213:Lymphocyte Activation; D010766:Phosphorylation; D043705:Receptor, Adenosine A2A / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D016511:Severe Combined Immunodeficiency / Q000201:enzymology / Q000276:immunology* / Q000473:pathology / Q000503:physiopathology*; D015398:Signal Transduction; D013379:Substrate Specificity; D014158:Transcription, Genetic
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D016207:Cytokines; D003839:Deoxyadenosines; D043705:Receptor, Adenosine A2A; D011948:Receptors, Antigen, T-Cell; D017868:Cyclic AMP-Dependent Protein Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D000243:Adenosine Deaminase