Endometrial inflammatory profile of the Pituitary pars intermedia dysfunction (PPID) mare
Category: Oral Presentation
Author(s): Jocelyn Howard
Presenter(s): Jocelyn Howard
Mentors(s): Carleigh Fedorka
Endometrial inflammatory profile of the Pituitary pars intermedia dysfunction (PPID) mare Howard, J.1; Hamner, I.1; Crook, R.1; Unger, G.1; Coleman, S.J.1; McCue, P.M.2; Fedorka, C.E.1 1. Department of Animal Sciences, Colorado State University, Fort Collins, CO, USA 2. Department of Clinical Sciences, Colorado State University, Fort Collins, CO, USA Pituitary pars intermedia dysfunction (PPID) is an endocrine disorder associated with elevated adrenocorticotropin hormone (ACTH). PPID animals have elevated systemic inflammation, and specifically an upregulation of the pro-inflammatory cytokine interleukin-8 (IL-8). It is unknown if this inflammation is noted with the reproductive tract. We hypothesize that elevated ACTH will lead to an increase in IL-8 expression in the endometrium, therefore predisposing mares to endometritis. Mares were screened for PPID using a thyrotropin-releasing hormone (TRH) stimulation test. Of these, seven mares were determined to be PPID positive (n=7; ACTH>110pg/mL), and four were determined to be PPID negative (n=4; ACTH<30 pg/mL). When in diestrus, an endometrial biopsy was obtained from all mares for qPCR analysis of select inflammatory cytokines. The impact of PPID on cytokine expression was evaluated using an unequal variances t-test. Correlation between ACTH and cytokine expression was assessed using a Pearson’s correlation. Significance was set to P<0.05. Of the cytokines evaluated, only IL-8 was found to increase in expression in the PPID population (P=0.02). There was a positive correlation between ACTH post-TRH stimulation and the endometrial expression of IL-8 (P<0.001; R2=0.80). A weak but positive correlation was also noted between ACTH and endometrial expression of IL-6 (P=0.04; R2=0.41) and IFNγ (P<0.01; R2=0.63). In conclusion, the systemic inflammation noted in the PPID animal is also observed within the endometrium. This increase in IL-8 may be associated with increased neutrophilia, which would be detrimental to the fertility of mares.