Assessing the inflammatory response in horses undergoing gastric ulceration using salivary ADA and S100A12 as biomarkers

The inflammatory status in horses with gastric ulcers was monitored by two inflammatory biomarkers, S100A12 and adenosine deaminase (ADA), using saliva samples from healthy and horses with gastric ulcers. Two trials were developed: an experimental trial, in which gastric ulceration was induced in 8 horses by feed deprivation, and a clinical trial, in which 20 horses without any symptomatology and 37 with symptoms compatible with gastric ulcers were used. S100A12 and ADA levels were measured in the saliva samples of all horses using previously validated assays. In both trials, horses with gastric ulcers had higher levels of S100A12 and ADA than healthy horses, demonstrating that inflammation is involved in the pathophysiology of gastric ulcers in horses. An intense reaction of ADA with a moderate increase of S100A12 was detected in the experimental trial, while different intensities in the inflammatory biomarkers were observed in clinical conditions when the ulcers were divided by gastric localization in glandular (EGGD) and squamous (ESGD). Since ADA has been shown to be released early in the inflammatory process and S100A12 is released later, by measuring them together we could more accurately assess the inflammatory process in equine gastric ulcers. Furthermore, a strong association was found between ADA and S100A12 (correlation coefficient of 0.84) in the experimental trial, while it was low-moderate (correlation coefficient of 0.39) in the clinical trial. Therefore, it could be concluded that both salivary biomarkers provide valuable information about the inflammation involved in gastric ulcers of horses and the state of the process.