Gleeson Michael, McFarlin Brian, Flynn Michael
School of Sport and Exercise Sciences, Loughborough University, Loughborough, Leicestershire LE11 3TU, UK.
Exerc Immunol Rev. 2006;12:34-53.
Toll-like receptors (TLRs) are highly conserved trans-membrane proteins that play an important role in the detection and recognition of microbial pathogens. The key product of TLR signalling in antigen presenting cells is the production of inflammatory cytokines and proteins. The TLR pathway plays an important role in mediating whole body inflammation, which has been implicated in the development of chronic disease. An accumulation of chronic, low-grade inflammation is common in individuals that live a sedentary lifestyle; however, the mechanism underlying this connection is not fully understood. There is evidence to show that TLRs may be involved in the link between a sedentary lifestyle, inflammation, and disease. Recent studies have shown that both acute aerobic and chronic resistance exercise resulted in decreased monocyte cell-surface expression of TLRs. Furthermore, a period of chronic exercise training decreases both inflammatory cytokine production and the cell-surface expression of TLR4 on monocytes. These effects may contribute to post-exercise immunodepression and the reported higher susceptibility to infection in athletes. However over the long-term, a decrease in TLR expression may represent a beneficial effect because it decreases the inflammatory capacity of leukocytes, thus altering whole body chronic inflammation. The precise physiological stimulus mediating an exercise-induced decrease in cell-surface TLR expression is not known; however a number of possible signals have been implicated including anti-inflammatory cytokines, stress hormones and heat shock proteins.
Toll样受体（TLRs）是高度保守的跨膜蛋白，在检测和识别微生物病原体中发挥重要作用。抗原呈递细胞中TLR信号传导的关键产物是炎性细胞因子和蛋白质的产生。TLR途径在介导全身炎症中起重要作用，而全身炎症与慢性疾病的发展有关。久坐不动的个体中常见慢性低度炎症的积累；然而，这种联系背后的机制尚未完全了解。有证据表明，TLRs可能参与久坐不动的生活方式、炎症和疾病之间的联系。最近的研究表明，急性有氧运动和慢性抗阻运动都会导致单核细胞表面TLRs表达降低。此外，一段时间的慢性运动训练会降低炎性细胞因子的产生以及单核细胞上TLR4的细胞表面表达。这些影响可能导致运动后免疫抑制以及运动员中报告的更高感染易感性。然而，从长期来看，TLR表达的降低可能代表一种有益作用，因为它会降低白细胞的炎症能力，从而改变全身慢性炎症。介导运动诱导的细胞表面TLR表达降低的确切生理刺激尚不清楚；然而，一些可能的信号已被牵连其中，包括抗炎细胞因子、应激激素和热休克蛋白。
