Acid sphingomyelinase involvement in tumor necrosis factor α-regulated vascular and steroid disruption during luteolysis in vivo

Abstract

TNF is well known for its role in inflammation, including direct effects on the vasculature. TNF also is implicated in the regulation of reproduction by its actions to affect ovarian steroidogenic cells and to induce apoptosis of corpus luteum (CL)-derived endothelial cells in vitro. We hypothesized that the disruption of TNF signaling would postpone the regression of the highly vascularized CL in vivo, and this effect could be replicated in mutant mouse models lacking TNF receptor (TNFRI ؊/؊ ) and/or a critical enzyme of TNF signaling, acid sphingomyelinase (ASMase ؊/؊ ). In the current study, the treatment of pseudopregnant mice with the luteolytic mediator prostaglandin F2-␣ (PGF) significantly increased TNF in the ovaries when compared with saline-treated controls. Treatment with PGF also reduced serum progesterone (P4) concentrations and caused involution of the CL. However, pretreatment of pseudopregnant mice with Etanercept (ETA), a TNF-neutralizing antibody, inhibited the PGF-induced decrease in P4 and delayed luteal regression. A similar outcome was evident in pseudopregnant TNFRI ؊/؊ animals. Treatment of luteal microvascular endothelial cells (MVECs) with TNF provoked a significant increase in ASMase activity when compared with the corresponding controls. Furthermore, TNF-induced MVEC death was inhibited in the ASMase ؊/؊ mice. The ASMase ؊/؊ mice displayed no obvious evidence of luteal regression 24 h after treatment with PGF and were resistant to the PGF-induced decrease in P4. Together these data provide evidence that TNF plays an active role in luteolysis. Further studies are required to determine the deleterious effects of antiinflammatory agents on basic ovarian processes.corpus luteum ͉ cytokines ͉ endothelial cells ͉ ovary ͉ progesterone

TGFB1 disrupts the angiogenic potential of microvascular endothelial cells of the corpus luteum

“…In the present study, TGFB1 did not reduce the viability of CLENDO cells plated on plastic. Previous studies provide evidence that TNF is capable of inducing apoptosis of bovine (Friedman et al, 2000;Pru et al, 2003) and murine (Henkes et al, 2008) CLENDO cells. Here, we show that TGFB1 did not alter TNF-induced reductions in CLENDO cell viability when plated on plastic culture CLENDO cells were grown to confluence on membrane inserts (3m pore).…”

“…The developing corpus luteum vascularizes extremely rapidly and, once formed, the maintenance of the vasculature is essential to preserve its functionality (Henkes et al, 2008;Pauli et al, 2005;Plendl, 2000). Therefore, improving our understanding of the factors involved in the development and regression of the luteal microvasculature is necessary for a greater understanding of ovarian cyclicity and fertility.…”

“…By contrast, ANGPT2 mRNA and protein levels rapidly increased following PGF2 administration (Berisha et al, 2010;Shirasuna et al, 2010;Tanaka et al, 2004). Likewise, PGF2 induced expression of TGFB1 (Hou et al, 2008) and TNF (Henkes et al, 2008) in luteal tissue. TNF adversely affects luteal endothelial cells by inducing acid sphingomyelinase and ceramide-induced apoptosis (Pru et al, 2003;Henkes et al, 2008).…”

“…During regression, the microvasculature is extensively disrupted (Henkes et al, 2008). Other than reports on luteal steroidogenic cells, there have been no studies to date that clearly identify the specific cells in the corpus luteum that produce or respond to TGFB1.…”

“…The expression of angiogenic factors, such as vascular endothelial growth factor (VEGF) (Berisha et al, 2010;Neuvians et al, 2004;Shirasuna et al, 2010), the angiopoietins (ANPGT1 and ANGPT2) (Berisha et al, 2010;Shirasuna et al, 2010;Tanaka et al, 2004) and cytokines such as TGFB1 (Hou et al, 2008) and TNF (Henkes et al, 2008), is acutely regulated during regression of the corpus luteum. Angiopoietins play a role in stabilization of capillaries; an elevated ratio of ANGPT2 : ANGPT1 decreases capillary stabilization, which, together with a low level of VEGF, results in blood vessel destabilization and regression (Yancopoulos et al, 2000).…”