Domestic horses routinely participate in vigorous and various athletic activities. This enables the horse to serve as a model for studying athletic physiology and immunology in other species, including humans. For instance, as a model of physical efforts, such as endurance rides (long-distance running/aerobic exercise) and races (anaerobic exercise), the horse can be useful in evaluating post-exercise response. Currently, there has been significant interest in finding biomarkers, which characterize the advancement of training and adaptation to physical exercise in the horse. The parallels in cellular responses to physical exercises, such as changes in receptor expression and blood cell activity, improve our understanding of the mechanisms involved in the body’s response to intense physical activity. This study focuses on the changes in levels of the pro- and anti-inflammatory cytokines and cellular response in the context of post-exercise immune response. Both the direction of changes in cytokine levels and cellular responses of the body, such as proliferation and expression of surface markers on lymphocytes, monocytes and neutrophils, show cross-functional similarities. This review reveals that horses are robust research models for studying the immune response to physical exercise in human athletes.

Green coffee extract is currently of great interest to researchers due to its high concentration of chlorogenic acid (CGA) and its potential health benefits. CGA constitutes 6 to 10% of the dry weight of the extract and, due to its anti-inflammatory properties, is a promising natural supplement and agent with therapeutic applications. The purpose of our study was to discover the effects of CGA on peripheral blood mononuclear cell proliferation, and the production of pro- and anti-inflammatory cytokines as well as reactive oxidative species (ROS) in horses during exercise. According to the findings, CGA can affect the proliferation of T helper cells. In addition, at a dose of 50 g/mL, CGA increased the activation of CD4+FoxP3+ and CD8+FoxP3+ regulatory cells. Physical activity decreases ROS production in CD5+ monocytes, but this effect depends on the concentration of CGA, and the effect of exercise on oxidative stress was lower in CD14+ than in CD5+ cells. Regardless of CGA content, CGA significantly increased the release of the anti-inflammatory cytokine IL-10. Moreover, the production of IL-17 was greater in cells treated with 50 g/mL of CGA from beginners compared to the control and advanced groups of horses. Our findings suggest that CGA may have immune-enhancing properties. This opens new avenues of research into the mechanisms of action of CGA and possible applications in prevention and health promotion in sport animals.

In a recent study, in which more than a thousand racehorses were evaluated, three potential blood markers were selected. It was concluded that insulin-like growth factor 1 (IGF1), interleukin-1 receptor antagonist (IL-1ra), and matrix metalloproteinase 2 (MMP2) may enable the early detection of horses at risk of injuries. However, in other studies, it was suggested that cytokine concentrations indicate the athlete’s status better than mRNA expression in blood cells. Thus, the purpose of this study was to evaluate changes in IGF1, MMP-2, and novel markers such as interleukin-13 (IL-13) after exercise in horses at different fitness levels as well as after different intensities of exercise. ELISA tests were performed on thirty-one racehorses [n = 31], who were divided into an inexperienced [beginner] group [n = 20] and an experienced [advanced] group [n = 6]. In addition, differences between race and training session were evaluated to see the influence of different intensities of exercise. Blood samples were taken before and after exercise. The basal IGF1 concentration was lower in an inexperienced group (p < 0.01) as well as IL-13 (p < 0.05) in comparison to the experienced group. There were no differences between pre- and post-exercise samples, changes in multiples or between training, and racing exercises. In conclusion, the basal values of some cytokines may appear to be more beneficial in forecasting horse fitness level.