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Received Feb 28, 2018; Accepted May 27, 2018
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1. Introduction
Juvenile idiopathic arthritis (JIA), the most common inflammatory pathology in children, is a chronic disease characterized by persistent joint inflammation due to immune system disruption [1]. Some of the proteins that perpetuate inflammatory mechanisms in JIA are calgranulins (myeloid-related protein (MRP)-8 and MRP-14). They are secreted by activated monocytes and phagocytes and induce the expression of proinflammatory cytokines (IL-1β, IL-6, or TNF) [2]. In JIA, the MRP8/14 complex, also called calprotectin, is a reliable marker of subclinical disease activity [3, 4].
It has emerged that exercise may have direct effects not only on metabolic and fitness parameters but also on the pathogenesis of autoimmune diseases as it attenuates chronic low-grade systemic inflammation [5]. After acute exercise of varying intensities and lengths, plasma calprotectin levels in healthy adults increase at a rate of between 3.4-fold (VO2 max test) and 96.3-fold (marathon) [6]. Although IL-6 is known as a potent proinflammatory signal (involved in the pathology of JIA), the transient rise in circulating IL-6 during exercise appears to have anti-inflammatory effects [7]. In addition, IL-6 released from contracting muscle acts in a hormone-like manner to mobilize extracellular substrates or inhibits low-level TNF-α production. Likewise, physical activity is known to impact the hypothalamic-pituitary-adrenal (HPA) axis in healthy children [8-10] and modulate the anti-inflammatory effect of cortisol. However, the disturbed HPA axis in JIA leads to impaired secretion of adrenocorticotropic hormone (ACTH) and cortisol [11, 12]. Even though physical activity is increasingly recognized as a useful intervention in patients with rheumatisms [13], to our knowledge, there is no data on the effect of acute bouts of physical activity on IL-6 and its receptors, calprotectin and HPA axis in children with inflammatory disease.
Here, we set out to explore the impact of an acute bout exercise on pain and on the secretion of molecules involved in the inflammatory process in JIA.
2. Methods
Twelve children aged 8 to 16 years with nonsystemic JIA according to the criteria of the International League of Associations for Rheumatology were...