Altered intracellular and extracellular signaling leads to impaired T-cell functions in ADA-SCID patients.
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.
Cassani
Barbara
B
San Raffaele Telethon Institute for Gene Therapy, Milan, Italy.
Mirolo
Massimiliano
M
Cattaneo
Federica
F
Benninghoff
Ulrike
U
Hershfield
Michael
M
Carlucci
Filippo
F
Tabucchi
Antonella
A
Bordignon
Claudio
C
Roncarolo
Maria Grazia
MG
Aiuti
Alessandro
A
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
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