Unique epithelial expression of S100A calcium binding protein A7A in the endometrium at conceptus implantation in pigs

Abstract

Objective S100A7A, a member of the S100 protein family, is involved in various biological processes, including innate immunity, antimicrobial function, and epithelial tumorigenesis. However, the expression and function of S100A7A in the endometrium during the estrous cycle and pregnancy are not well understood in pigs. Therefore, this study determined the expression and regulation of S100A7A at the maternal-conceptus interface in pigs. Methods We obtained endometrial tissues from pigs throughout the estrous cycle and pregnancy, conceptus tissues during early pregnancy, and chorioallantoic tissues during mid- to late pregnancy and analyzed the expression of S100A7A in these tissues. We also determined the effects of steroid hormones, estradiol-17β (E 2 ) and progesterone, and interleukin-1β (IL1B) on S100A7A expression in endometrial tissues. Results We found that S100A7A was expressed in the endometrium during the estrous cycle and pregnancy in a pregnancy status- and stage-dependent manner and was localized to endometrial luminal epithelial (LE) and superficial glandular epithelial cells with strong intensity in LE cells on day 12 of pregnancy. Early stage conceptuses and chorioallantoic tissues from day 30 to term pregnancy also expressed S100A7A . The expression of S100A7A was increased by E 2 and IL1B in endometrial tissues. Conclusion S100A7A was expressed at the maternal-conceptus interface at the initiation of implantation in response to conceptus-derived estrogen and IL1B and could be a unique endometrial epithelial marker for conceptus implantation in pigs. These findings provide an important insight into the understanding of conceptus-endometrial interactions for the successful establishment of pregnancy in pigs.

Spatiotemporal expression and regulation of peptidase inhibitor 3 and secretory leukocyte protease inhibitor at the maternal–fetal interface in pigs

“…In humans, the expression of PI3 peaks during menstruation, and the expression of SLPI peaks during the late secretory phase of the menstrual cycle [ 10 , 15 ]. We previously reported that several AMPs, such as the cathelicidin family [ 22 ], the S100 family [ 23 , 24 ], and the beta-defensin family (Lee and Ka, unpublished data), are also differentially expressed in the endometrium during the estrous cycle and at the maternal–conceptus interface during pregnancy in pigs. In this study, we found that PI3 and SLPI are expressed in the endometrium throughout the estrous cycle and pregnancy.…”

Minerals and the Menstrual Cycle: Impacts on Ovulation and Endometrial Health

“…During pregnancy, the amount of calcium in the uterine endometrial tissue increases, and calcium deposits are made at the site where the embryo implants in the uterus. These are critical steps for the onset of pregnancy [45,369,370]. The hormone estrogen has been identified as a factor that increases the uptake of calcium in the body and influences the activity of specific genes [371,372] in the endometrium that are crucial for the initiation of pregnancy [45,369,370].…”

“…These are critical steps for the onset of pregnancy [45,369,370]. The hormone estrogen has been identified as a factor that increases the uptake of calcium in the body and influences the activity of specific genes [371,372] in the endometrium that are crucial for the initiation of pregnancy [45,369,370]. Among the significant genes related to uterine function and development is the Homeobox A10 (HOXA10) gene [373].…”

Conceptus-derived cytokines interleukin-1β and interferon-γ induce the expression of acute phase protein serum amyloid A3 in endometrial epithelia at the time of conceptus implantation in pigs

“…Because the expression of SAA3 in the endometrium was greatest on Day 12 during pregnancy and implanting porcine conceptuses secrete estrogen and cytokines, IL1B and IFNG, we postulated that the conceptus-derived estrogen and cytokines would increase endometrial SAA3 expression. Estrogen of conceptus origin is responsible for inducing the expression of many endometrial genes, such as aldo-keto reductase 1B1, fibroblast growth factor 7, IFN-alpha and beta receptor subunit 2, IFNG receptor beta subunit, lysophosphatidic acid receptor 3, S100A7A, S100A8, and secreted phosphoprotein 1 [1,3,28]. IL1B and IFNG also increase the expression of many endometrial genes involved in PG synthesis and transport and immunity, respectively [1].…”

“…In mice and humans, SAAs synthesized from intestinal epithelial cells act as opsonins that activate phagocytes by binding to outer membrane protein A of bacteria, and they also show antimicrobial activity [7]. Our previous studies have shown that the maternal endometrium and conceptus tissues during pregnancy in pigs produce a variety of antimicrobial peptides (AMPs), including cathelicidins [31], S100A7A [28], S100A8, S100A9, S100A12 [32], β-defensin family, peptidase inhibitor 3, and secretory leukocyte protease inhibitor (Lee and Ka, unpublished data). Therefore, our results in this study suggest that SAA3 expressed at the maternal-conceptus interface acts as a component of endometrial and choriallantoic AMPs that protect implantation sites from possible contamination by microorganisms and maintain fertility during pregnancy.…”