Genetic Polymorphism of the Nrf2 Promoter Region (rs35652124) Is Associated with the Risk of Diabetic Foot Ulcers

Abstract

The genetic polymorphism in the nuclear factor erythroid 2-related factor 2 (Nrf2) gene has been reported as one of the prognosis markers for various diseases, including cancer. Nrf2 is a key transcription factor involved in wound healing by regulating angiogenesis. We investigated the genetic association of NRF2 single-nucleotide polymorphism rs35652124 with T2DM and DFU and assessed its functional impact. A total of 400 subjects were recruited for the study and categorized into three groups: infected DFU patients (DFU, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mi>n</mml:mi><mml:mo>=</mml:mo><mml:mn>100</mml:mn></mml:math>), T2DM patients without complications (T2DM, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mi>n</mml:mi><mml:mo>=</mml:mo><mml:mn>150</mml:mn></mml:math>), and healthy adults with normal glucose tolerance (NGT, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:mi>n</mml:mi><mml:mo>=</mml:mo><mml:mn>150</mml:mn></mml:math>). The subjects were genotyped by PCR-RFLP, and the polymorphism was identified by bidirectional Sanger sequencing. The expression of NRF2 , IL-10 , TNF-α , and IL-6 was studied by qPCR to evaluate the functional impact of rs35652124. The “TT” genotype of rs35652124 was associated with a significant risk for T2DM [<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M4"><mml:mtext>OR</mml:mtext><mml:mo>=</mml:mo><mml:mn>2.2</mml:mn></mml:math> (1.2-4.2), <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M5"><mml:mi>p</mml:mi><mml:mo>=</mml:mo><mml:mn>0.01</mml:mn></mml:math>] and DFU [<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M6"><mml:mtext>OR</mml:mtext><mml:mo>=</mml:mo><mml:mn>7.9</mml:mn></mml:math> (4-14.9), <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M7"><mml:mi>p</mml:mi><mml:mo>&lt;</mml:mo><mml:mn>0.0001</mml:mn></mml:math>]. A significant decrease in transcriptional levels of NRF2 and IL-10 and a remarkable increase in TNF-α and IL-6 were observed in subjects with TT genotype. In conclusion, rs35652124 (TT) is a harmful genetic variant that predisposes to insulin resistance and impaired angiogenesis. Hence, it may serve as a diagnostic genetic marker for T2DM and DFU in combination with different inflammatory markers.