Spermadhesin PSP-I/PSP-II heterodimer induces migration of polymorphonuclear neutrophils into the uterine cavity of the sow

The heterogeneous seminal plasma (SP) is involved in endometrial inflammation and following immune changes that occur post-mating in pigs. This study tested whether SP spermadhesins (binding heparin [HBPs] or not [PSP I/PSP II]) recruit different lymphocyte subsets (CD2+, CD4+ and CD8+) and polymorphonuclear leukocytes (PMNs) to the superficial endometrium/lining epithelium and lumen, respectively, of oestrous sows, in vivo. In Experiment 1, endometrial biopsies were taken under narcosis from six sows whose uterine horns were separated and their lumen infused with 3 mg/mL spermadhesins (HBP resp PSP I/PSP II) in 100 mL saline (treatment horn) or 100 mL saline (control horn). Endometrial samples removed between 2 and 120 min post-infusion were studied by immunohistochemistry (IHC, using mABs) or histology, to assess the degree of T cell respectively PMN entry over time. In Experiment 2, eight conscious oestrous sows were singly infused intra-utero with 3 mg/mL of PSP I/PSP II in 100 mL saline (n = 4) or 100 mL of saline (n = 4), to assess relative PMN numbers in the uterine lumen, 3 h post-infusion. Compared to controls, PSP I/PSP II infusion significantly recruited uterine lymphocytes from 10 min (CD2+) or from 60 min (CD8+) onwards, while HBPs had only increased CD4+ cells by 120 min. As well, PSP I/PSP II, but not HBPs, significantly (P < 0.05) induced an early (10 min) PMN migration to the surface epithelium, 5 fold by 30 min and 7 fold from 60 min onwards (P < 0.001), with PMNs visible in the lumen from 30 min of infusion. Six fold more PMNs were collected from the uterine lumen of PSP I/PSP II-infused sows compared to controls, 3 h after infusion (P < 0.001). Seminal plasma PSP I/PSP II heterodimer triggers the entry of cleansing uterine PMNs, initiating a cascade of transient and long-lasting immunological events in oestrous sows