Systemic inflammation index and Platelet-ToLymphocyte as effort markers in endurance horses competing in different distances

Introduction

The integrative cellular markers neutrophil-to-lymphocyte ratio (NLR), platelets-to-lymphocyte ratio (PLR) and systemic immune inflammation index (SII) have been emerging in human medicine as an inflammation marker in many types of cancer and vascular disease, however, few studies have assessed this potential value in the context of exercise.

The aims of this study were to verify the immune response to different distances in endurance riding and evaluate if the immune inflammation indexes could be used an effort marker.

Materials And Methods

Twenty Arabian horses were studied in an endurance race competing in 160 km, 120 km, and 80 km. Sample times were in rest (T0), right after and 3 h after the final vet check (T1 and T2). Laboratory analyses consisted of leukocyte count and differential, platelets count, T lymphocyte immunophenotyping, cortisol, and interleukins (IL-1, IL-2, IL-4, IL-10, TNF and IFN) level determination. Data was analyzed by one-way ANOVA and Tukey’s test (p<0.05 considered significant).

Results

All horses showed a cortisol increasing in T1 and decreasing in T2. Neutrophils count increased up to T2 and lymphocyte count decreased. LTCD4+/CD8+ showed a shift in Th1 and Th2 response in 120 km and 80 km horses. The pro-inflammatory cytokine’s changes were more pronounced in 80km horses and the anti-inflammatory cytokines levels increased in in all horses. NLR remained increased in T2 and both PLR and SII were increased in T1 and decreased in T2.

Discussion and Conclusions

The endurance exercise resulted in a cellular immune disturbance up to and including 3 hours post-race, higher in the less experienced horses.

SII and PLR may represent a promisor method to routinely examine (anti-)inflammatory responses. However, to enable regular assessment, resting values for athletes’ horses and the kinetics in more prolonged recovery periods have to be established.

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