Secreted surfactant protein A from fetal membranes induces stress fibers in cultured human myometrial cells

Abstract

In the present study, we investigated the ability of human fetal membranes (amnion and choriodecidua) to regulate human maternal uterine cell functions through the secretion of surfactant protein (SP)-A and SP-D at the end of pregnancy. We detected the expression of both SP-A (SP-A1 and SP-A2) and SP-D by quantitative reverse transcription polymerase chain reaction. Immunohistochemistry revealed that human fetal membranes expressed both SP-A and SP-D. By Western blot analysis, we demonstrated that SP-A protein expression was predominant in choriodecidua, whereas the amnion predominantly expressed SP-D. Only the secretion of SP-A was evidenced in the culture supernatants of amnion and choriodecidua explants by immunodot blot and confirmed by Western blot. Exogenous human purified SP-A induced stress fiber formation in cultured human myometrial cells via a pathway involving Rho-kinase. Conditioned medium from choriodecidua and amnion explants mimicked the SP-A effect. Treatment of myometrial cells with SP-A-depleted conditioned medium from choriodecidua or amnion explants failed to change the actin dynamic. These data indicate that SP-A released by human fetal membranes is able to exert a paracrine regulation of F-actin filament organization in myometrial cells. myometrium; pregnancy REGULATION OF LABOR PROCESSES involves cross-talk between maternal and fetal compartments. Thus, the roles of locally produced factors acting on myometrium need further exploration. The fetal membranes are located in the vicinity of the myometrium and are then ideally positioned to regulate signaling pathways between mother and fetus at the time of labor (for review, see (1,10,15,20,22,31,38) and can be detected as early as 26 wk of pregnancy in amniotic fluid. SP-D levels rise only slightly during pregnancy, whereas SP-A levels rise sharply from 32 wk toward term (29,34) and then decline in spontaneous parturition at term (3). Condon et al. (5) have described SP-A as a link between fetal lung development and the timing of labor in the mouse. Their thesis was that SP-A secreted by the fetal lung into amniotic fluid near term activates macrophages in the amniotic fluid, priming their migration to the maternal uterus and ultimately causing a functional "progesterone withdrawal" and labor through a NF-B-driven inflammation response. However, trafficking of fetal macrophages into the myometrium of women with labor at term does not occur (16,18). In addition, the human fetal membranes are thought to be extrapulmonary sources of SP-A and SP-D (29). To date, only the expression of SP-A1 has been found in human fetal membranes (13), and an induction of SP-A expression by cortisol has been reported in cultured chorionic trophoblasts (40).In the present study, we addressed the question of whether SP-A and SP-D originating from the human fetal membranes can directly regulate human maternal uterine cell functions. We previously reported the ability of SP-A to bind and to serve as a signal in human uterine smooth muscle cells (11). We first analy...

In vivo rescue of alveolar macrophages from SP-A knockout mice with exogenous SP-A nearly restores a wild type intracellular proteome; actin involvement

“…The inclusion of so many of the significantly changing proteins (n = 11) in the actin/cytoskeleton-related protein group out of 20 significant changes between WT and KO indicates that SP-A has a profound influence on actin-related/cytoskeletal processes such as macrophage motility and phagocytosis, potentially explaining the susceptibility of the KO mice to injury or infection. In vitro studies have shown that an intact actin cytoskeleton, as assessed by the use of cytochalasin D, an actin depolymerizing agent, is required for certain SP-A-mediated processes [44] and in extrapulmonary tissues SP-A regulates F-actin filament organization [45]. Although given the importance of actin in cell motility, phagocytosis, and endocytosis, it is not surprising that changes in these proteins do occur, but the extent to which SP-A affects the content of so many actin/cytoskeletal-related proteins in vivo is remarkable.…”

“…Moreover, virtually nothing is known about the in vivo effect of SP-A on the alveolar macrophage proteome under basal or unstimulated conditions, with regards to whether and which groups of proteins SP-A may affect under such conditions. However, based on recent in vitro studies, in response to LPS [44] or in extrapulmonary tissues [45], it appears that the integrity of the cytoskeleton is required in order for SP-A-mediated processes to occur.…”

Expression of surfactant proteins SP-A and SP-D in murine decidua and immunomodulatory effects on decidual macrophages

“…Expression of SP-A and SP-D has also been reported in extra pulmonary tissues such as brain, salivary glands, lachrymal glands, heart, trachea, kidney, pancreas, thymus, spleen, gall bladder, esophagus, small intestine, large intestine, testis, prostate and urinary tract (Madsen et al, 2003;Herías et al, 2007;Breuiller-Fouché et al, 2010;Nayak et al, 2012;Schicht et al, 2015). In addition, reproductive tissues have also been shown to express both SP-A and SP-D (Sati et al, 2009;Condon et al, 2004;Yadav et al, 2011).…”

Structure, genetics and function of the pulmonary associated surfactant proteins A and D: The extra-pulmonary role of these C type lectins

“…Quantitative real-time RT-PCR demonstrated expression of SP-A1 mRNA, which was 17.4-fold higher in patients delivering preterm with chorioamniotis. Several studies have also established that SP-A is an important marker that increases during the intricate signaling that mediates parturition (Breuiller-Fouche et al, 2010; Chaiworapongsa et al, 2008; Garcia-Verdugo et al, 2010; Leong et al, 2008; Salminen et al, 2008; Snegovskikh et al, 2011; Yadav et al, 2011). Most recently, statistically significant delay in the time to parturition was evident in SP-A and D doubly deficient mice (Montalbano et al, 2013).…”