[Decreased caspase 3 expression and cytotoxic T lymphocyte antigen-4 polymorphism in Chilean patients with type 1 diabetes].
BACKGROUND
Several polymorphisms of the CTLA4 gene have been associated with autoimmune diseases. The activation of induced cell death is the major event and caspase 3 represents the main protein for the apoptotic machinery, especially in lymphocytes.


OBJECTIVE
To correlate CTLA4 polymorphisms with caspase 3 expression in peripheral blood mononuclear cells (PBMC) simulating in vitro the glucose effect.


METHODS
CTLA4 polymorphisms were determined by restriction fragment length polymorphisms (RFLPs). PBMC from 21 patients with type 1 diabetes aged 8.5 ± 4.3 years and 21 healthy subjects aged 18.3 ± 1.8 years, were stimulated under normal (5 mM) and toxic (14 mM) glucose conditions to assess its effect on the expression and activity of caspase 3. Relative abundance of caspase 3 mRNA was measured by semi quantitative RT-PCR and its activity, by a colorimetric assay.


RESULTS
When stimulated with 14 mM glucose, PBMC of G allele carriers with type 1 diabetes had significantly lower relative mRNA abundance of caspase 3 (median value = 0.12, range 0.01-0.70 AU) compared with non-carriers (median value = 0.81, range 0.06-1.09 AU). When the incubation was carried out with the lower glucose concentration, a similar profile of caspase 3 activity was observed in diabetic patients carrying G allele (median value = 0.57, range 0.13-1.20 AU) as compared with non-carriers (median value = 0.89, range 0.14-5.50 AU). No significant changes after stimulating with glucose, were observed in PBMCs of the control group.


CONCLUSIONS
PBMC of recently diagnosed patients with T1D, carrying the G allele in + 49A/G polymorphisms of CTLA4, have a decreased expression and activity of caspase 3.
Departamento de Nutrición, Salud Pública y Epidemiología Genética, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, Chile.
Bárbara B
BB
Angel
Ethel
E
Codner
Miguel O
MO
Arredondo
Francisca P
FP
Salas
Carolina A
CA
Pizarro
Francisco B
FB
Pérez
D000293:Adolescent; D000483:Alleles; D017209:Apoptosis; D060908:CTLA-4 Antigen / Q000235:genetics*; D016022:Case-Control Studies; D053148:Caspase 3 / Q000172:deficiency*; D002648:Child; D003922:Diabetes Mellitus, Type 1 / Q000201:enzymology* / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000201:enzymology; D008297:Male; D011110:Polymorphism, Genetic / Q000235:genetics*; D012150:Polymorphism, Restriction Fragment Length
D060908:CTLA-4 Antigen; D053148:Caspase 3