Prostaglandin-Endoperoxide Synthase 2 (PTGS2) Expression Is Increased in Chronic Asymptomatic Orchitis in the Dog

Chronic asymptomatic orchitis (CAO) in dogs lacks effective treatment options. To elucidate the involvement of prostaglandin endoperoxide synthase 2 (PTGS2), associated with inflammation and physiological steroidogenesis, testicular PTGS2 and StAR gene (via RT-qPCR) and protein expression (via immunohistochemistry) were analyzed in 11 canine CAO samples and compared to five normospermic control group (CG) samples. The percentage of immunopositive area (PIA) and mean gray scale (MGS) intensity were evaluated in the interstitial and tubular compartments. In CAO, PTGS2 and StAR gene expression levels were significantly increased compared to CG (p < 0.001 and p = 0.0034). Leydig cells and some peritubular cells stained immunopositive for PTGS2 and StAR and Sertoli cells positive for PTGS2. PIA and MGS for PTGS2 differed significantly between groups in the interstitial (PIA: p < 0.0001; MGS: p = 0.0051) and tubular (PIA: p = 0.0006; MGS: p = 0.0413) compartments. For StAR, PIA, but not MGS, was significantly higher in CAO (p = 0.0010). Except for PTGS2 gene expression, higher degrees of spermatogenetic impairment correlated with more prominent expression changes. This study demonstrates an association between increased PTGS2 expression and CAO. Further research is needed to investigate potential clinical benefits of selective PTGS2 inhibitors.