Global gene expression analysis in PBMCs of individuals from normal and high level natural radiation areas of Kerala Coast, India

Gene expression changes in human populations exposed to chronic low level radiation have important implications. There are few areas around the world where human population is exposed to elevated levels of natural background radiation. The high level natural radiation areas (HLNRAs) of Kerala coast in south west India is unique for its wide variation in the background radiation dose (<1.0mGy to 45mGy/year). The areas with a background radiation dose of ≤ 1.5mGy/year are considered as normal level natural radiation areas (NLNRA), whereas areas with > 1.5mGy/year are considered as HLNRA. We used microarray analysis to find out global changes in gene expression in peripheral blood mononuclear cells (PBMCs) of individuals belonging to different HLNRA groups as compared to individuals from normal level natural radiation areas (NLNRA). Blood samples were collected from individuals of four different background dose groups (Normal level natural radiation areas (Group I, ≤1.5mGy/year, N=9) and three dose groups of high level natural radiation areas (Group II, 1.51-5.0mGy/year, N=9; Group III, 5.01-15.0mGy/year, N=11; and Group IV, >15.0mGy/year, N=7)). Peripheral blood mono-nuclear cells were isolated from each blood sample and used for RNA extraction and hybridization to Affymetrix Chip.

长期暴露于低剂量辐射的人群所发生的基因表达变化，具有重要的研究价值与现实意义。全球范围内，自然本底辐射水平升高且有人类聚居的区域十分稀少。印度西南部喀拉拉邦海岸的高天然辐射区（High Level Natural Radiation Areas, HLNRAs）因其本底辐射剂量跨度极大（不足1.0mGy/年至45mGy/年）而独具研究特色。本底辐射剂量≤1.5mGy/年的区域被定为正常本底辐射区（Normal Level Natural Radiation Areas, NLNRA），而剂量>1.5mGy/年的区域则被归类为HLNRA。本研究采用微阵列分析技术，对比分析高天然辐射区不同剂量组与正常本底辐射区人群外周血单个核细胞（Peripheral Blood Mononuclear Cells, PBMCs）的全基因组基因表达变化。研究共招募四组不同本底辐射剂量人群并采集血液样本：正常本底辐射区组（第I组，≤1.5mGy/年，N=9），以及三个高天然辐射剂量组（第II组：1.51~5.0mGy/年，N=9；第III组：5.01~15.0mGy/年，N=11；第IV组：>15.0mGy/年，N=7）。从每份血液样本中分离外周血单个核细胞，随后进行RNA提取，并与Affymetrix芯片进行杂交实验。