Equine Asthma Does Not Affect Circulating Myostatin Concentrations in Horses.

Simple Summary: The increase in the number of horses suffering from chronic respiratory diseases prompted us to undertake research on markers useful in the quick and accurate diagnosis of asthma in horses. Recent studies provide evidence for the usefulness of one myokine in the diagnosis of human asthma, namely, myostatin. Myostatin is an extracellular cytokine mostly expressed in skeletal muscles and known to play a crucial role in the negative regulation of muscle mass and function. Therefore, our aim was to compare the concentration of myostatin in the blood plasma of completely healthy and asthmatic horses. The research was carried out in two stages. In the first stage, horses with severe asthma were selected, and in the second stage, the myostatin level was determined in horses classified as asthmatic or healthy (controls). The experimental results did not provide a clear answer as to whether myostatin can be used as a reliable marker confirming the occurrence of equine asthma. Its level in horses suffering from asthma and healthy horses of similar age and use did not differ statistically, but was significantly higher compared to that in young race horses. Thus, further studies are needed to confirm our findings in a larger population of horses. (1) Background: The number of horses suffering from chronic respiratory diseases, resembling human asthma, is increasing but there is still a lack of reliable and accurate methods to detect these disorders. Numerous studies have found elevated plasma concentrations of one of the myokines, namely, myostatin (MSTN), in people suffering from severe asthma. MSTN normally inhibits myoblast proliferation and differentiation through autocrine or paracrine signals. Therefore, given the pathogenesis of asthma, we hypothesize that MSTN could be a useful biomarker of equine asthma. Thus, this study aimed to compare the concentration of MSTN in the blood plasma of fully healthy and asthmatic horses. (2) Methods: A total of 61 horses were clinically examined to confirm or exclude the occurrence of equine asthma, including bronchoalveolar lavage (BAL) fluid cytology performed on 49 horses. This study included three groups of horses, two of which were clinically healthy, and one of which was asthmatic. (3) Results: The mean circulatory MSTN concentration determined using the ELISA method in asthmatic horses was significantly higher than that in clinically healthy young Thoroughbred racehorses (p < 0.05), but it did not differ as compared to the group of healthy, adult leisure horses. (4) Conclusions: The obtained results did not unambiguously support our original hypothesis that MSTM may be a reliable marker for the early diagnosis of equine asthma. To the best of the authors' knowledge, this is the first study to analyze the plasma MSTN concentration in equine asthma patients, and therefore further studies are needed to confirm our novel findings. [ABSTRACT FROM AUTHOR]