儿童噬血性淋巴组织细胞增生症GDF15 mRNA表达及意义

Expression and implication of growth differentiation factor 15 mRNA in peripheral blood in children with HLH

目的研究噬血性淋巴组织细胞增生症(HLH)患儿生长分化因子15(GDF15)mRNA表达情况,探讨GDF15表达改变的机制和意义。方法选取2011年4月至2012年2月四川大学华西第二医院儿童血液肿瘤科收治的初诊HLH患儿为HLH组,选取同期年龄、性别与HLH组匹配的健康体检儿童为对照组。Omega Blood RNA Kit提取外周血总RNA,逆转录制备cDNA后Eva Green定量RT-PCR方法,检测HLH组和对照组的GDF15、Fn-H、HIF1α和HIF2α mRNA表达水平,△△Ct方法计算基因相对表达量。检测血生化指标。结果 HLH组18例,对照组19例。HLH组和对照组GDF15 mRNA相对中位表达量分别为4.584和1.490,HLH组显著高于对照组(P=0.039);HLH组Fn-H mRNA表达水平显著高于对照组,相对中位表达量分别为3.955和1.690(P=0.008),并与GDF15 mRNA相对表达呈正相关(r=0.573,P=0.013);HLH组和对照组HIF1α和HIF2α mRNA相对表达水平差异无统计学意义(P分别为0.282和0.311);GDF15 mRNA相对表达水平与初诊时最低Hb水平呈负相关(r=-0.576,P=0.015),与血清铁蛋白、乳酸脱氢酶、网织红细胞计数、三酰甘油和纤维蛋白原水平无相关性。结论 HLH患儿外周血细胞GDF15 mRNA表达显著升高,但不依赖于HIF介导的缺氧感知信号路径。HLH情况下巨噬细胞异常持续活化很可能是GDF15和Fn-H mRNA表达上调的主要机制。

Objective To investigate the mRNA expression of growth differentiation factor 15 （GDF15） in peripheral blood from children with newly diagnosed hemophagocytic lymphohistiocytosi （ HLH）, and to explore the underlying mechanism and clinical implication. Methods Eighteen children with newly diagnosed HLH according to the HLH-2004 diagnostic criteria of the Histiocyte Society and 19 age- and sex-matched healthy children as controls were enrolled in this study. Total RNA was extracted from trace peripheral blood using commercial Omega Blood RNA Kit. Expression of GDF15 mRNA together with ferritin heavy chain （Fn-H） and hypoxic inducible factor （HIF）lc~ and 2oL was determined by EvaGreen real-time RT-PCR, with each sample run in duplicates. Relative expression of target gene was calculated via A ACt protocol against house-keeping 13-actin gene. Complete blood count, serum ferritin and other hemochemical parameters were determined by routine methods. Results Relative expression level of GDF15 mRNA in HLH group was significantly higher than that in control group, with medians of expression being 4. 584 and 1. 490 respectively （P = 0. 039 ）. Similarly, Fn-H expression was markedly upregulated in HLH group than that in control group, with median expressions of 3. 955 and 1. 690 respectively （ P = 0. 008 ）. In addition, GDF15 expression was positively correlated with Fn-H expression （ r = 0. 573, P = 0. 013 ）, and negatively correlated with the lowest Hb concentration at diagnosis in HLH group （ r = - 0. 576, P = 0. 015 ）. Nevertheless, GDF15 expression was not correlated to serum ferritin level and other biochemical indeces in HLH group. There were no significantly difference in terms of HIFlol and HIF2a expressions between HLH and cont,.ol groups. Conclusions Our findings that GDFI5 mRNA was remarkably upregulated and independent of HlF-mediated oxygen sensing pathway in children with HLH, strongly suggested GDF15 indtion was most probably triggered hy sustained and excessive macrophage activation, the hallmark of HLH, and helped suppress tkmher activation of macrophages.