内脏脂肪过多与心脏病和癌症风险增高相关

《美国心脏病学会杂志》(JACC)7月10日在线发表的一项针对Framingham心脏研究受试者的研究显示，在校正临床危险因素和一般肥胖后，内脏脂肪过多与偶发心血管疾病(CVD)和癌症相关。


Kathryn Britton医生

由于很少有学者对异位脂肪患者的前瞻性转归进行研究，因此布里格姆妇女医院心血管医学科的Kathryn A. Britton医生及其同事从Framingham心脏研究中纳入3,086例患者，探讨了直接影像学测定的脂肪与偶发CVD、癌症和全因死亡的关联。所有患者接受8层多探测器CT扫描，以识别和测定内脏脂肪组织、心包脂肪组织和主动脉旁脂肪组织区域。中位随访5年期间，在校正标准危险因素后评估心脏疾病、癌症和死亡风险。

这些患者的平均年龄为50岁；51%为男性。随访结束时，共观察到90例心血管事件、141例癌症和71例死亡。采用Cox比例危险回归模型进行多变量校正后，研究者发现内脏脂肪组织每增加1个标准偏差与CVD(HR，1.44；P=0.01)和癌症(HR，1.43；P=0.005)相关。上述3种脂肪组织均与全因死亡无关。

Britton博士表示，许多实验研究表明内脏脂肪组织与参与多种疾病转归发生机制的重要生物学通路潜在相关。脂肪因子是这些通路的关键成分，包括炎性细胞因子、血管生成因子、脂质代谢产物和细胞外基质成分。不同脂肪组织的脂肪因子分泌情况不同，内脏脂肪组织的促炎症和血管形成基因表达水平高于皮下脂肪组织。

研究者承认该研究存在一些局限性，如研究样本主要为白人且未获得随访期间患者体重改变的数据。研究者总结称，上述研究结果进一步证实了异位脂肪的致病作用。鉴于全球性的肥胖流行，识别高危患者具有重要意义，因为这有利于制订对应的预防和治疗措施。此外，危险标志物有助于我们了解体脂分布与转归之间的生物学关联。

该研究获美国国立心肺血液研究所(NHLBI)的Framingham心脏研究支持。Britton博士获NHLBI的研究职业发展奖支持。

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By: DOUG BRUNK, Cardiology News Digital Network

Excessive visceral fat was associated with incident cardiovascular disease and cancer after adjustment for clinical risk factors and general adiposity, results from a study of Framingham Heart Study participants showed.

The findings "support the growing appreciation of a pathogenic role of ectopic fat," researchers led by Dr. Kathryn A. Britton of the division of cardiovascular medicine at Brigham and Women’s Hospital, Boston, reported. The study was published online July 10 in the Journal of the American College of Cardiology. "Given the worldwide obesity epidemic, identification of high-risk individuals is important as it allows targeting of preventive and therapeutic measures. Furthermore, markers of risk may provide insight into the biology linking body fat distribution and outcomes."

Since few studies have examined prospective outcomes in people with ectopic fat, the researchers set out to examine the association of directly-imaged fat measurements with incident CVD, cancer, and all-cause mortality in 3,086 participants from the Framingham Heart Study. All of the patients underwent multidetector computerized tomography with an 8-slice scanner in an effort to identify and measure areas of visceral adipose tissue, pericardial adipose tissue, and periaortic adipose tissue. During a median follow-up of 5 years, the study participants were assessed for heart disease, cancer, and death risk after adjustment for standard risk factors.

The mean age of the 3,086 patients was 50 years; 51% were men. At the end of the follow-up period, there were 90 cardiovascular events, 141 cancer cases, and 71 deaths. After multivariable adjustment using Cox proportional hazards regression models, the researchers found that each standard deviation increase in visceral adipose tissue was associated with cardiovascular disease (HR 1.44; P =.01) and cancer (HR 1.43; P = .005). None of the fat depots were associated with all-cause mortality.

"Numerous experimental studies support a potential link between visceral adipose tissue and biological pathways important in the pathogenesis of multiple disease outcomes," Dr. Britton and her colleagues wrote. "Adipokines, biologically active molecules secreted from adipose tissue, are key components of these pathways and include inflammatory cytokines, angiogenic factors, lipid metabolites, and extracellular matrix components. Adipokine secretion appears to differ between specific fat depots with visceral adipose tissue demonstrating greater expression of proinflammatory and proangiogenic genes, compared with subcutaneous adipose tissue."

The researchers acknowledged certain limitations of the study including the fact that the study sample was predominately white and that weight change data were not available on the participants during the follow-up period.

The study was supported by the National Heart, Lung and Blood Institute’s Framingham Heart Study. Dr. Britton was supported by a Research Career Development Award from the NHLBI.