Effect of strenuous exercise and ex vivo TLR3 and TLR4 stimulation on inflammatory gene expression in equine pulmonary leukocytes.

This study examines the impact of strenuous exercise on the expression of certain inflammatory genes in horses’ lung immune cells. Using physical stress and immune pathway stimulation, the researchers found that strenuous exercise can dampen the lung cells’ responsiveness to immune triggers and potentially weaken the horse’s pulmonary immune response following intense exertion.

Research Overview

• The investigation looked into the effects of powerful physical exercise and manipulation of TLR3 and TLR4 immune pathways on the display of six inflammatory genes in equine pulmonary leukocytes or lung immune cells.
• The selected genes were interferon-beta (IFN-β), interleukin-1-beta (IL-1β), interleukin-6 (IL-6), interferon gamma-induced protein 10 (IP-10), chemokine (c-c motif) ligand 5 (RANTES), and tumor necrosis factor-alpha (TNF-α) – all key players in immune response.
• The researchers proposed that strenuous physical activity would alter baseline gene expression and also change the response to bacterial lipopolysaccharide (LPS) and to polyinosinic:polycytidylic acid (Poly IC) – two substances known for instigating immune reactions.

Methodology

• Young Thoroughbred mares, eight in number, were chosen for the study.
• Performing bronchoalveolar lavages (a technique used to obtain lung cells) 48 hours prior and 24 hours post treadmill session allowed the research team to assess before and after effects of strenuous treadmill exercise.
• Gene expression in the resulting lung immune cells was examined by utilizing quantitative real-time PCR analysis, a method key in detecting and comparing amounts of specific genes.
• All measured gene expression was compared to three housekeeping genes (HKG) – genes whose constant expression levels act as a control for ensuring accurate, unbiased results.

Findings

• No considerable changes were noted in mRNA expression of the six examined cytokines – immune signaling proteins – between pre and post exercise cells.
• LPS and Poly IC both prompted significant increases of TNF-α, IFN-β, IL-6, IL-1β (for LPS) and IP-10 and RANTES (for Poly IC), regardless of whether it was prior to or following exercise.
• Despite these increases, a significant degradation in the gene response to LPS and Poly IC following exercise was observed, implying exercise can lessen the responsiveness of these genes to immune stimulus.
• The conclusions drawn from this study imply that heavy treadmill exercise may have a negative effect on some aspects of the pulmonary immune response in horses 24 hours after high-intensity physical activity.