Raloxifene inhibits adipose tissue inflammation and adipogenesis through Wnt regulation in ovariectomized rats and 3 T3-L1 cells
Raloxifene inhibits adipose tissue inflammation and adipogenesis through Wnt regulation in ovariectomized rats and 3 T3-L1 cells
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DOI：
10.1186/s12929-019-0556-3
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发表时间：
2019-08-31
影响因子：
11
通讯作者：
Lee, Yen-Mei
中科院分区：
文献类型：
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作者：
Shen, Hsin-Hsueh;Yang, Chien-Yi;Lee, Yen-Mei
绝经期或卵巢切除术（OVX）后的卵巢功能丧失与肥胖和白色脂肪组织（WAT）炎症密切相关。雌激素替代疗法可以预防绝经后肥胖，但会增加致癌风险。在本研究中，我们研究了雷洛昔芬（RAL），一种选择性雌激素受体调节剂，长期治疗对雌激素缺乏引起的肥胖的特征的影响，并探讨了体内和体外典型和非典型Wnt调节的参与。方法成年雌性大鼠行双侧卵巢切除术，随机分为5组：（1）假手术组（Sham），（2）卵巢切除组（OVX），（3）卵巢切除+ E-2组：卵巢切除大鼠皮下注射E-2（50 μ g/kg，3次/周），（4）OVX + RAL：OVX大鼠用混悬于0.8%羧甲基纤维素（CMC）中的RAL（灌胃，1 mg/kg/天）处理，（5）OVX + CMC：0.8% CMC作为溶剂对照。所有治疗均在OVX后1周开始给予8周。在3 T3-L1细胞中，评价RAL对脂肪生成和脂多糖（LPS）诱导的炎症的影响。结果RAL治疗组大鼠体重、内脏脂肪垫重量、脂肪细胞大小和血糖水平显著降低，但血浆脂联素水平显著升高。RAL通过抑制NF-kappa B p65和JNK级联降低了腹膜后WAT中HIF-1 α、VEGF-A和促炎细胞因子（MCP-1和TNF-α）表达的升高。RAL的这种抗炎能力可能是由于分泌的卷曲相关蛋白5（SFRP 5）的上调，SFRP 5是抑制Wnt 5a信号传导的脂肪因子。此外，RAL抑制成脂因子，如PPAR-gamma、C/EBP-α和FABP 4，并保留典型的Wnt 10 b/β-连环蛋白表达。在3个T3-L1脂肪细胞中，RAL（20 μ M）减少脂质积累，抑制脂肪形成因子，同时诱导β-连环蛋白，这被β-连环蛋白抑制剂IWR-1-endo有效逆转。此外，RAL减少LPS诱导的NF-κ B p65和p-I κ B表达以及TNF-α分泌。通过小干扰RNA抑制SFRP 5可显著消除RAL的抗炎作用。结论经典β-catenin抑制脂肪生成和非经典SFRP 5抑制WAT炎症可能是RAL的有益作用。因此，本研究为RAL治疗绝经后肥胖的潜力提供了理论依据。
Background Loss of ovarian function, as in menopause or after ovariectomy (OVX), is closely associated with obesity and white adipose tissue (WAT) inflammation. Estrogen replacement protects against postmenopausal obesity but increases the risks of carcinogenesis. In the present study, we investigated the effects of long-term treatment of raloxifene (RAL), a selective estrogen receptor modulator, on the features of estrogen deficiency-induced obesity and explored the involvement of canonical and non-canonical Wnt regulation in vivo and in vitro. Methods Adult female rats received bilateral OVX and divided into 5 groups: (1) Sham, (2) OVX, (3) OVX + E-2: OVX rats were administered with E-2 (50 mu g/kg, s.c., 3 times/week), (4) OVX + RAL: OVX rats were treated with RAL (gavage, 1 mg/kg/day) suspended in 0.8% carboxymethylcellulose (CMC), (5) OVX + CMC: 0.8% CMC as vehicle control. All treatments were given for 8 weeks beginning at 1 week after OVX. In 3 T3-L1 cells, the effects of RAL on adipogenesis and lipopolysaccharide (LPS)-induced inflammation were evaluated. Results Treatment with RAL significantly decreased body weight, visceral fat pad mass, adipocyte size and plasma levels of glucose but increased plasma adiponectin. RAL reduced the elevation of HIF-1 alpha, VEGF-A and proinflammatory cytokines (MCP-1 and TNF-alpha) expression by inhibition of NF-kappa B p65 and JNK cascades in retroperitoneal WAT. This anti-inflammatory capacity of RAL may result from upregulation of secreted frizzle-related protein 5 (SFRP5), an adipokine that repressed Wnt5a signaling. Furthermore, RAL inhibited adipogenic factors such as PPAR-gamma, C/EBP-alpha, and FABP4, and preserved canonical Wnt10b/beta-catenin protein expression. In 3 T3-L1 adipocytes, RAL (20 mu M) diminished lipid accumulation and inhibited adipogenic factors accompanied with the induction of beta-catenin, which were effectively reversed by the beta-catenin inhibitor IWR-1-endo. In addition, RAL reduced LPS-induced NF-kappa B p65 and p-I kappa B expression as well as TNF-alpha secretion. Suppression of SFRP5 by small interfering RNA significantly abrogated the anti-inflammatory effects of RAL. Conclusions Distinct activation of canonical beta-catenin on inhibition of adipogenesis and non-canonical SFRP5 on suppression of WAT inflammation may contribute to the beneficial effects of RAL. Therefore, this study provides a rationale for the therapeutic potential of RAL for postmenopausal obesity.