Cytokine profiles of autologous protein solution (APS) and autologous conditioned serum (ACS) from horses with pituitary pars intermedia dysfunction (PPID) and healthy horses: A preliminary investigation

Middle-aged horses are commonly affected by joint disease, and within this population, endocrine disease, such as pituitary pars intermedia dysfunction (PPID), is prevalent. PPID has also been shown to affect immune function. While orthobiologics such as autologous protein solution (APS) and autologous conditioned serum (ACS) have been used in this group, there is a gap in knowledge on how PPID affects the anti-inflammatory nature of these products. The main hypothesis of this study was that horses with PPID would have altered cytokine profiles in APS and ACS compared to healthy horses. Six horses with previously diagnosed PPID and six healthy horses at a single farm had blood drawn aseptically and processed for APS and ACS per manufacturer’s directions. Pro- and anti-inflammatory cytokine concentrations (IL-1β, TNF-α, IL-6, IL-1Ra, IL-4, IL-10, TGF-β1, IGF-1) were determined in duplicate using validated immunoassays. Groups were compared with ANOVA, Student’s t-tests, and Wilcoxon rank sum tests (P<0.05). For both APS and ACS, there was no significant difference in any cytokine concentrations between PPID and healthy horses (P > 0.06). When data from all horses were combined, there was a significantly higher concentration of TGF-β1 in APS (median: 8,344 pg/mL) compared to ACS (median: 4,617 pg/mL) (P=0.002). These data suggest PPID does not significantly change the cytokine profile of the APS and ACS preparations tested. These results support further investigation of orthobiologics in aged horses with PPID. • PPID and healthy horses had similar cytokine profiles in APS and ACS. • In ACS, IL-4 had less variability in PPID compared to healthy horses. • In APS, IL-1RA had less variability in PPID compared to healthy horses.