A proinflammatory response of bovine endometrial epithelial cells to active sperm in vitro

Abstract

In the cow, cryopreserved semen is inseminated into the uterus, and most of sperm are removed by backflow and phagocytes. Nevertheless, the mechanism responsible for sperm phagocytosis is unclear. Here, we used cultured bovine uterine epithelial cells (BUECs) to investigate the uterine response to sperm and the mechanism that activates polymorphonuclear neutrophils (PMNs). BUEC monolayers were co-cultured with different numbers of washed sperm obtained from cryopreserved semen (10 , 10 , and 10 sperm/ml) for 3 hr. Sperm dose-dependently up-regulated IL8 (Interleukin 8). Sperm at 10 /ml increased mRNA expression of TNFA (Tumor necrosis factor alpha), IL1B (Interleukin 1B), NFKB2 (Nuclear factor kappa B2), and C3 (Complement factor 3), as well as PGES (Prostaglandin E synthase) expression and PGE release. Live sperm, but not dead sperm, attached to BUECs, and dead sperm did not induce an acute inflammatory response. Time-dependent effects were evaluated by co-culture of 10 /ml washed sperm with BUECs for 0, 1, 3, and 6 hr. The number of detached sperm increased gradually toward 6 hr. Maximum mRNA expression of IL8, TNFA, IL1B, and NFKB2 was induced at 3 hr, while C3 continued to increase toward 6 hr. Sperm did not stimulate mRNA expression of anti-inflammatory cytokines TGFB1 (Transforming growth factor beta 1) or IL10 (Interleukin 10). Medium conditioned by sperm co-incubated with BUECs stimulated PMNs phagocytosis of sperm in vitro. Fresh media supplemented with low levels of IL1B, TNFA, and PGE up-regulated sperm phagocytosis by PMNs as well. In conclusion, our findings strongly suggest that the active sperm attach to BUECs and trigger uterine local innate immunity with induction of a pro-inflammatory response that enhances sperm phagocytosis by PMNs.

Persistent Breeding-Induced Endometritis in Mares—A Multifaceted Challenge: From Clinical Aspects to Immunopathogenesis and Pathobiology

“…Additionally, work in other species indicates that human and murine sperm express TLR2 and TLR4, although this has not been confirmed in the horse [151]. In bovine, in vitro studies suggested that sperm can stimulate transcription of pro-inflammatory cytokines, including chemokines (TNFα, IL1β, CXCL8) and prostaglandin E and activate the local complement system (C3) mediated via TLR2/4 [152][153][154].…”

Effect of Exposure to Seminal Plasma Through Natural Mating in Cattle on Conceptus Length and Gene Expression

“…Despite the extensive body of evidence in the mouse, in cattle, the effect of SP on embryo development and survival is not clear. Both sperm and SP have been shown to induce expression of proinflammatory-related genes in the endometrium after infusion of SP into the bovine uterus (Elweza et al, 2018;Ibrahim et al, 2019;Ortiz et al, 2019). However, using a similar infusion technique, no improvement in the fertility of dairy heifers (Odhiambo et al, 2009) or cows (Ortiz et al, 2019) was observed.…”

“…These apparent inter-species differences in the role of SP in fertility may be due, in part, to the known variation in composition of this fluid (Rodger, 1976;Druart et al, 2013), owing to differences in accessory gland size, type and level of fluid contribution to the ejaculate (Bedford, 2015). Indeed, caution is needed when interpreting some of the aforementioned bovine studies as some used SP collected by electroejaculation (Ibrahim et al, 2019), others by artificial vagina (Odhiambo et al, 2009) and others do not mention the collection method (Elweza et al, 2018;Ortiz et al, 2019). Collection method significantly influences the composition of SP (Rego et al, 2015) and consequently has a tremendous impact on endometrial response in vitro (Fernandez-Fuertes et al, 2019).…”

“…In fact, some SP proteins that bind to sperm, such as Binder of Sperm Protein (Suarez and Pacey, 2006) and osteopontin (Souza et al, 2008), have previously been described to influence embryo development in vitro in pigs (Hao et al, 2008) and cattle (Gonçalves et al, 2008;Monaco et al, 2009;Rodríguez-Villamil et al, 2016). However, although bovine sperm can bind to both endometrial and oviductal cells in vitro and stimulate mRNA expression of different cytokines (Yousef et al, 2016;Elweza et al, 2018;Ezz et al, 2019), incubation of endometrial explants with cauda epididymis sperm (which are mature but have had no contact with SP) or Percollwashed ejaculated sperm did not induce differences in mRNA expression of some of those cytokines (Fernandez-Fuertes et al, 2019). Thus, it is not clear if SP-derived proteins, rather than intrinsic sperm proteins, are responsible for eliciting changes in the endometrium of cattle.…”

Immune regulatory molecules as modifiers of semen and fertility: A review

“…Sperm binding to BOECs promotes a shift to an anti‐inflammatory response by upregulating IL10, TGFB, and PGE2 and downregulates sperm phagocytosis by PMN via PGE2 (Marey et al, ). Thus, the bovine oviduct provides a rich immune tolerant environment to protect sperm from phagocytosis while supporting sperm survival in the oviduct (Elweza et al, ; Marey et al, ).…”