Association between fungal detection and inflammatory response
A significant positive association was found between fungal detection by culture in BALF and a high tracheal mucus score, as well as with a high percentage of neutrophils in BALF. When present (>10%) the magnitude of neutrophilic response was however not significantly associated with the prevalence of mold in BALF. Tracheal mucus accumulation and neutrophil proportions are evidence of airway inflammation, but without specific cause.5
Fungal exposure and its association with SA have frequently been documented,8,43,44 but studies examining fungal association with MA are still scarce. One study found that horses with fungal elements observed in TW cytology had twice the odds of having IAD than horses without fungi.10 There is also little information to date concerning the association between antigenic triggers and specific MA phenotypes.45 Neutrophilic airway inflammation in BALF of racing Thoroughbreds has been correlated with both respirable dust and endotoxin exposure, while mast cell inflammation in BALF has been associated with β-glucan exposure.9 Interestingly, our results tend to demonstrate the lack of association between fungal detection in the airways and non-neutrophilic forms (mast-cell and eosinophilic) of pulmonary inflammation. These elements suggest that fungal detection in the airways is not linked to a specific immune response.