Endocrine Abstracts

Introduction

The Indoleamine 2.3-dioxygenase (IDO) is an enzyme involved in tryptophan metabolism, encoded by the IDO1 gene in humans. In Caucasians, the rs9657182 polymorphism of IDO gene was found to be associated with neurobehavioral complications, especially depression. Several studies in Type 2 Diabetes Mellitus (T2DM) describe psychological factors as barriers to the successful implementation of a healthy eating plan. According to our knowledge there is a lack of data that relates the IDO polymorphism with oxidative status and inflammation in T2DM.

Aim

1) To evaluate the distribution of the genotypic and allelic isolated and combined frequencies of the IDO polymorphism; 2) To study a possible association of this polymorphism with biomarkers of oxidative status, diabetes metabolic control and inflammation.

Material and methods

Observational analytical epidemiological study in 150 Caucasian adults with T2DM aged 40–75 years. Two groups were formed: GI75 patients with angiopathy and GII75 patients without angiopathy. The IDO genotypes were identified using the endpoint analysis method. Blood levels of malondialdehyde, ascorbic acid (AA), homocystein (Hcy), Hemoglobin A1c, vitamins B6, B12 and B9 were measured by HPLC methods. Creactive protein (CRP) serum levels were achieved by ultrasensitive immunoturbidimetric assay. Statistical analysis was performed using SPSS, version 26.0. Statistical significance was considered for P < 0.05.

Results

CT genotype was the most prevalent (GI: 52.9%; GII: 38.5%) and the CC genotype was the least frequent (G: 13.7%; GII: 21.2%). There were no significant differences between groups in the distribution of genotypic and allele frequencies of the IDO polymorphism, but there were differences between sexes (α = 0.025). The average blood concentrations of AA and vitamin B12 were significantly higher (α = 0.049; α = 0.025; respectively) in subjects with the TT genotype compared to the CC + TC genotypes. Mean value of CRP was statistically lower in TT genotype (α = 0.044). Having the TT genotype seems to be associated with a decreased risk of having low AA blood levels (OR = 0.363 [0.155–0.850]; α = 0.020) and higher CRP plasma levels (OR = 0.310 [0.126–0.762]; α=0.011). This genotype was also associated with an increased risk of having higher concentrations of Hcy (OR = 3.238 [1.340–7.824]; α = 0.009).

Conclusion

The TT genotype of the IDO gene rs9657182 polymorphism seems to offer protection against inflammation (< CRP levels) and cardiovascular disease (< Hcys values), as well as, favoring the antioxidant capacity by association with higher vitamin C concentrations in patients with T2DM.