Endometrial transcripts of proinflammatory cytokine and enzymes in prostaglandin synthesis are upregulated in the bitches with atrophic pyometra

•Uterus was histologically categorized into hyperplastic (HP) and atrophic (AP) pyometra in the bitch.•Endometrial transcripts of IL-6, IL-8, COX2 and PGFS were significantly upregulated in AP.•A positive correlation of IL-8 with COX2 and PGFS was found in AP group. Inflammatory markers of endometrial origin are valuable in order to differentiate the pyometra from cystic endometrial hyperplasia in the bitch. In the present study, we hypothesized that histological categorization would distinguish the differential regulation of the proinflammatory genes in the endometrium of bitches with pyometra. Ovariohysterectomy was done on bitches with confirmatory diagnosis of pyometra (n = 18). Using endometrium to myometrium ratio of 0.79 as threshold, the uteri (n = 8/group) were categorized into hyperplastic pyometra (HP) and atrophic pyometra (AP). Two samples were excluded as the diagnosis was inconclusive. In parallel, endometrial tissue was collected for total RNA extraction to study the differential expression of TLR4, IL-6, IL-8, COX-2 and PGFS through real time PCR. Diestrus uterus of non-pyometra bitches (n = 6) served as control. The mean fold change (2−ΔΔCt) for the target genes was determined using β-actin as endogenous control and non-pyometra uterus as calibrator group. Except TLR4, other inflammatory genes were upregulated significantly by 1.82 to 3.74 times in the AP as compared to HP with maximum upregulation of COX-2 and PGFS. Further, correlation matrix with Spearman’s rho revealed that IL-8 had strong positive correlation with COX-2 and PGFS in the AP group (P