Effects of intravaginal infusion of the osteopontin peptide possessing integrin-binding motifs on an inflammation-like response in the endometrium of dairy cows.

Intravaginal infusion of a peptide possessing the integrin-binding motifs of osteopontin (OPN peptide), a seminal protein, restored fertility in dairy cows by restoring the endometrial epidermal growth factor profile. Hypothetically, this treatment induces an inflammation-like response in the endometrium, which may modulate endometrial function. The present study aimed to determine whether intravaginal treatment with OPN peptide induces an inflammation-like response in the endometrium. Holstein lactating cows were infused with OPN peptide (peptide, n = 7) or vehicle only (control, n = 7) into the vagina 16-24 h after the second gonadotropin-releasing hormone treatment using the Ovsynch protocol. Endometrial, vaginal, and peripheral blood mononuclear cells (PBMC) were collected immediately before and 4 h after treatment. Endometrial gene expression of IL1A,IL1B,IL8, and TNF and the percentage of polymorphonuclear cells (PMN%) in smears were evaluated. Gene expression in the vagina and in PBMCs and PMNs, and PMN% in vaginal smears, were also examined in some cows. The results revealed that the OPN peptide increased endometrial IL1B and IL8 expression and PMN%. In vaginal samples, the OPN peptide increased PMN%, despite no differences in cytokine expression between the groups. IL1A and IL1B expression in PBMCs decreased after treatment in both groups; however, their degrees of decrease in the peptide group were smaller than that in the control group. These data demonstrate that intravaginal infusion of OPN peptide induces an inflammation-like response in the endometrium as well as vaginal and potentially systemic immune responses in cows.