Obesity versus osteoarthritis: beyond the mechanical overload

Obesity is currently considered a major public health problem in the world, already reaching epidemic characteristics, according to the World Health Organization. Excess weight is the major risk factor associated with various diseases, such as type 2 diabetes mellitus, hypertension, dyslipidemia and osteometabolic diseases, including osteoporosis and osteoarthritis. Osteoarthritis is the most prevalent rheumatic disease and the leading cause of physical disability and reduced quality of life of the population over 65 years. It mainly involves the joints that bear weight - knees and hips. However, along with the cases of obesity, its prevalence is increasing, and even in other joints, such as hands. Thus, it is assumed that the influence of obesity on the development of OA is beyond mechanical overload. The purpose of this review was to correlate the possible mechanisms underlying the genesis and development of these two diseases. Increased fat mass is directly proportional to excessive consumption of saturated fatty acids, responsible for systemic low-grade inflammation condition and insulin and leptin resistance. At high levels, leptin assumes inflammatory characteristics and acts in the articular cartilage, triggering the inflammatory process and changing homeostasis this tissue with consequent degeneration. We conclude that obesity is a risk factor for osteoarthritis and that physical activity and changes in diet composition can reverse the inflammatory and leptin resistance, reducing progression or preventing the onset of osteoarthritis.

据世界卫生组织（World Health Organization）统计，肥胖当前已成为全球重大公共卫生难题，且已演变为流行病态势。体重超标是诸多疾病的核心危险因素，涵盖2型糖尿病（type 2 diabetes mellitus）、高血压（hypertension）、血脂异常（dyslipidemia），以及包括骨质疏松症（osteoporosis）和骨关节炎（Osteoarthritis, OA）在内的骨代谢疾病（osteometabolic diseases）。骨关节炎是最为高发的风湿性疾病，同时也是65岁以上人群肢体残疾与生活质量降低的首要原因，其主要累及负重关节——膝关节与髋关节。不过，随着肥胖病例的增多，骨关节炎的患病率也呈上升趋势，甚至可累及手部等其他关节。据此推测，肥胖对骨关节炎发生发展的影响，并非仅由机械负荷过载所介导。本综述旨在阐明这两种疾病的发生与发展背后的潜在关联机制。脂肪总量的增加与饱和脂肪酸过量摄入呈正相关，后者可诱发全身性低度炎症状态，并引发胰岛素与瘦素（leptin）抵抗。当瘦素水平过高时，其会显现出炎症特性并作用于关节软骨，触发炎症进程并破坏该组织的稳态，最终导致退行性病变。本研究最终得出结论：肥胖是骨关节炎的危险因素，而体育运动与膳食结构优化可逆转炎症状态与瘦素抵抗，从而延缓骨关节炎的进展，或预防其发病。