Athletic humans and horses: comparative analysis of interleukin-6 (IL-6) and IL-6 receptor (IL-6R) expression in peripheral blood mononuclear cells in trained and untrained subjects at rest.
BACKGROUND
Horses and humans share a natural proclivity for athletic performance. In this respect, horses can be considered a reference species in studies designed to optimize physical training and disease prevention. In both species, interleukin-6 (IL-6) plays a major role in regulating the inflammatory process induced during exercise as part of an integrated metabolic regulatory network. The aim of this study was to compare IL-6 and IL-6 receptor (IL-6R) mRNA expression in peripheral blood mononuclear cells (PBMCs) in trained and untrained humans and horses.


RESULTS
Nine highly trained male swimmers (training volume: 21.6 ± 1.7 h/wk in 10-12 sessions) were compared with two age-matched control groups represented by eight lightly trained runners (training volume: 6.4 ± 2.6 h/wk in 3-5 sessions) and nine untrained subjects. In addition, eight trained horses (training volume: 8.0 ± 2.1 h/wk in 3-4 sessions) were compared with eight age-matched sedentary mares. In humans, IL-6 mRNA levels in PBMCs determined by quantitative reverse transcription-polymerase chain reaction were significantly higher in highly trained subjects, whereas IL-6R expression did not differ among groups. In horses, transcripts of both IL-6 and IL-6R were significantly up-regulated in the trained group.


CONCLUSIONS
Up-regulation of IL-6R expression in PBMCs in horses could reflect a mechanism that maintains an adequate anti-inflammatory environment at rest through ubiquitous production of anti-inflammatory cytokines throughout the body. These findings suggest that the system that controls the inflammatory response in horses is better adapted to respond to exercise than that in humans.
Centro di Studio del Cavallo Sportivo, Dipartimento di Patologia, Diagnostica e Clinica Veterinaria, Università degli Studi di Perugia, Via San Costanzo 4, 06126 Perugia, Italia. capemaster@gmail.com
Stefano
S
Capomaccio
Katia
K
Cappelli
Giacomo
G
Spinsanti
Marzia
M
Mencarelli
Michela
M
Muscettola
Michela
M
Felicetti
Andrea
A
Verini Supplizi
Marco
M
Bonifazi
D000328:Adult; D000818:Animals; D005260:Female; D005786:Gene Expression Regulation; D006736:Horses; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000235:genetics; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D008297:Male; D012333:RNA, Messenger / Q000096:biosynthesis; D019947:Receptors, Interleukin-6 / Q000096:biosynthesis* / Q000235:genetics; D012146:Rest / Q000502:physiology*; D013045:Species Specificity; D013177:Sports / Q000502:physiology*; D055815:Young Adult
D015850:Interleukin-6; D012333:RNA, Messenger; D019947:Receptors, Interleukin-6
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