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Published on: June 16, 2011
[Decreased caspase 3 expression and cytotoxic T lymphocyte antigen-4 polymorphism in Chilean patients with type 1
Bárbara B Angel1, Ethel Codner, Miguel O Arredondo
1Departamento de Nutrición, Salud Pública y Epidemiología Genética, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, Chile.
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.
Aim:
To correlate CTLA4 polymorphisms with caspase 3 expression in peripheral blood mononuclear cells (PBMC) simulating in vitro the glucose effect.
Material And 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.
Insights
Type 1 diabetes patients with the CTLA4 gene G allele show reduced caspase 3 expression and activity, particularly under high glucose conditions. This finding highlights a potential mechanism linking genetic variations to altered apoptosis in T1D.
Area of Science:
- Immunogenetics
- Molecular Biology
- Cellular Biology
Context:
- CTLA4 gene polymorphisms are linked to autoimmune diseases.
- Caspase 3 is a key protein in lymphocyte apoptosis.
- Type 1 diabetes (T1D) involves immune dysregulation.
Purpose:
- To investigate the correlation between CTLA4 gene polymorphisms and caspase 3 expression in peripheral blood mononuclear cells (PBMCs).
- To assess the in vitro effect of varying glucose concentrations on this correlation.
Summary:
- PBMCs from T1D patients carrying the G allele of the CTLA4 +49A/G polymorphism exhibited significantly lower caspase 3 mRNA abundance and activity when exposed to high glucose (14 mM).
- No significant changes in caspase 3 expression or activity were observed in PBMCs from healthy controls under similar glucose conditions.
- These results suggest a glucose-dependent impairment of apoptotic pathways in T1D patients with specific CTLA4 genotypes.
Impact:
- Provides insights into the molecular mechanisms underlying T1D pathogenesis.
- Identifies a potential genetic marker (CTLA4 G allele) associated with altered apoptotic response in T1D.
- May inform future therapeutic strategies targeting apoptosis in autoimmune diseases.
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