Ovarian hormone suppression and regulation of adipogenesis in women

说明(申请人提供)：雌激素缺乏会导致女性体重增加，特别是腹部脂肪增加。绝经后向中心性肥胖的转变可能会增加代谢综合征和相关慢性疾病(即2型糖尿病、冠状动脉疾病、高血压)的风险。长期目标是了解雌激素缺乏导致腹部肥胖症增加的机制。R21的主要目的(PA1)是确定绝经前妇女的卵巢激素抑制是否会触发腹部脂肪组织中脂肪生成的增加(即细胞数量增加)。这将通过测量细胞大小分布的变化和在非基质(即成熟脂肪细胞)部分细胞的DNA中掺入氚(2H)来进行评估。次要目的是确定：SA2)卵巢激素抑制对脂肪形成相关因子(C/EBP1，PPAR3)和巨噬细胞浸润标志物(CD68，EMR-1)和炎症标志物(IL-6，TNF-1)的mRNA表达的影响；以及SA3)使用能够通过流式细胞仪检测的细胞表面标志物(Notch 4，血小板衍生生长因子受体(PDGFR)2，整合素15，CD36)是否从非居住的骨髓祖细胞(BMP)细胞分化出新的脂肪细胞。为了实现这些目标，24名绝经前妇女将在卵巢激素抑制30天和60天之前和之后通过促性腺激素释放激素激动剂加用安慰剂(GnRHAG+PL)或雌二醇(GnRHAG+E2)进行研究。假设：H1a)与GnRHAG+E2相比，GnRHAG+PL 60天将导致较小脂肪细胞(&lt；40 5m)的更大增加。由于GnRHAG+PL期间脂肪质量增加，小脂肪细胞数量的增加将被解释为脂肪生成的增加，而不是脂肪细胞萎缩的证据；H1b)与GnRHAG+E2相比，非基质细胞部分DNA中2H的掺入将增加。由于非间质部分含有成熟的脂肪细胞，富含2H的DNA的增加应反映脂肪的形成；h2)卵巢激素抑制会增加与脂肪生成、巨噬细胞浸润和炎症相关的因子(C/EBP1、PPAR3、CD68、EMR-1、IL-6、TNF-1)的mRNA表达，与基线相比(GnRHAG+PL前与GnRHAG+PL后)以及与E2添加后相比(GnRHAG+PL与GnRHAG+E2相比)；以及H3)卵巢激素抑制将增加BMP来源的脂肪细胞与基线(GnRHAG+PL前与GnRHAG+PL后)以及AG与E2添加后的比较(GnRHPL+与GnRHAG+E2)。据我们所知，这将是第一次在体内研究E2作为人类脂肪生成调节因子的作用。因为人们相信脂肪细胞是被编程来获得一定数量的脂肪的，脂肪细胞数量的增加将导致脂肪质量的增加，这将是非常难以逆转的。因此，确定有效防止卵巢激素停用期间脂肪生成增加的策略具有重要的临床意义。 公共卫生相关性：妇女在绝经前很大程度上避免了腹部肥胖。绝经时雌激素的丢失会引发腹部脂肪堆积的增加，这可能会增加代谢综合征、2型糖尿病、冠状动脉疾病和高血压的风险。这项拟议的研究将检验这一新的假设，即雌激素缺乏通过触发脂肪细胞数量的增加而导致腹部脂肪增加。

DESCRIPTION (provided by applicant): Estradiol (E2) deficiency triggers weight gain, and specifically abdominal fat gain, in women. The shift toward central adiposity after menopause likely contributes to increased risk for the metabolic syndrome and associated chronic diseases (i.e., type 2 diabetes, coronary artery disease, hypertension). The long-term aim is to understand the mechanisms by which E2 deficiency mediates increases in abdominal adiposity. The primary aim (PA1) of the R21 is to determine whether ovarian hormone suppression in premenopausal women, which is known to cause fat gain, triggers an increase in adipogenesis (i.e., increase in cell number) in abdominal adipose tissue. This will be assessed by measuring the changes in cell size distribution and the incorporation of deuterium (2H) into DNA of cells in the non-stromal (i.e., mature adipocyte) fraction. Secondary aims are to determine: SA2) effects of ovarian hormone suppression on mRNA expression of factors involved in adipogenesis (C/EBP1, PPAR3) and markers of macrophage infiltration (CD68, Emr-1) and inflammation (IL-6, TNF-1); and SA3) whether new adipocytes arise from non-resident bone marrow progenitor (BMP) cells using cell surface markers (Notch 4, Platelet-derived Growth Factor Receptor (PDGFR) 2, Integrin 15, CD36) that enable detection by flow cytometry. To achieve these aims, 24 premenopausal women will be studied before and after 30 and 60 days of ovarian hormone suppression via gonadotropin releasing hormone agonist therapy with add-back of placebo (GnRHAG+PL) or estradiol (GnRHAG+E2). Hypotheses are: H1a) GnRHAG+PL for 60 days will result in a larger increase in small adipocytes (<40 5m) when compared with GnRHAG+E2. Because fat mass increases during GnRHAG+PL, an increase in the number of small adipocytes will be interpreted as an increase in adipogenesis and not as evidence of adipocyte atrophy; H1b) The incorporation of 2H in the non-stromal cell fraction DNA will be increased in response to GnRHAG+PL, as compared with GnRHAG+E2. Because the non-stromal fraction contains mature adipocytes, an increase in 2H- enriched DNA should reflect adipogenesis; H2) Ovarian hormone suppression will increase mRNA expression of factors associated with adipogenesis, macrophage infiltration, and inflammation (C/EBP1, PPAR3, CD68, Emr-1, IL-6, TNF-1) when compared with baseline (before vs after GnRHAG+PL) and when compared with E2 add-back (GnRHAG+PL vs GnRHAG+E2); and H3) Ovarian hormone suppression will increase BMP-derived adipocytes when compared with baseline (before vs after GnRHAG+PL) and when compared with E2 add-back (GnRHAG+PL vs GnRHAG+E2). To the best of our knowledge, this will be the first in vivo study of the role of E2 as a regulator of adipogenesis in humans. Because it is believed that adipocytes are programmed to achieve a certain volume of fat, an increase in adipocyte number would lead to a gain in fat mass that would be very difficult to reverse. Thus, identifying strategies that effectively prevent an increase in adipogenesis during ovarian hormone withdrawal would be of high clinical importance. PUBLIC HEALTH RELEVANCE: Women are largely protected against abdominal adiposity prior to the menopause. The loss of estrogen at the time of the menopause triggers an increase in abdominal fat accumulation, which likely contributes to increased risk for the metabolic syndrome, type 2 diabetes mellitus, coronary artery disease, and hypertension. The proposed studies will test the novel hypothesis that estrogen deficiency results in abdominal fat gain by triggering an increase in the number of fat cells.