Perforin Rapidly Induces Plasma Membrane Phospholipid Flip-Flop

The cytotoxic cell granule secretory pathway is essential for host defense. This pathway is fundamentally a form of intracellular protein delivery where granule proteases (granzymes) from cytotoxic lymphocytes are thought to diffuse through barrel stave pores generated in the plasma membrane of the target cell by the pore forming protein perforin (PFN) and mediate apoptotic as well as additional biological effects. While recent electron microscopy and structural analyses indicate that recombinant PFN oligomerizes to form pores containing 20 monomers (20 nm) when applied to liposomal membranes, these pores are not observed by propidium iodide uptake in target cells. Instead, concentrations of human PFN that encourage granzyme-mediated apoptosis are associated with pore structures that unexpectedly favor phosphatidylserine flip-flop measured by Annexin-V and Lactadherin. Efforts that reduce PFN mediated Ca influx in targets did not reduce Annexin-V reactivity. Antigen specific mouse CD8 cells initiate a similar rapid flip-flop in target cells. A lipid that augments plasma membrane curvature as well as cholesterol depletion in target cells enhance flip-flop. Annexin-V staining highly correlated with apoptosis after Granzyme B (GzmB) treatment. We propose the structures that PFN oligomers form in the membrane bilayer may include arcs previously observed by electron microscopy and that these unusual structures represent an incomplete mixture of plasma membrane lipid and PFN oligomers that may act as a flexible gateway for GzmB to translocate across the bilayer to the cytosolic leaflet of target cells

Reproductive outcomes after laparoscopic surgery in infertile women affected by ovarian endometriomas, with or without in vitro fertilisation: results from the SAFE (surgery and ART for endometriomas) trial

We performed a retrospective cohort study, namely “Surgery and ART for Endometriomas” (SAFE) trial (Clinical Trial ID: NCT03717870), including women who underwent laparoscopic cystectomy for endometrioma before first IVF and compared their reproductive outcomes with the ones of women without endometriosis and with unexplained infertility, tubal factor or male factor infertility. We found that women who underwent previous laparoscopic cystectomy for endometrioma had higher FSH and LH levels between the 2nd and 5th day of the cycle before IVF, required higher doses of gonadotrophins for ovarian stimulation and had a lower number of retrieved oocytes compared with other types of infertility. Nevertheless, pregnancy and delivery rates remain comparable to other causes of infertility. In addition, differences in ovarian stimulation parameters between endometriosis and other types of infertility lost significance with the increase of women’s age. These pieces of information can be considered useful to make adequate counselling about reproductive outcomes for infertile women with ovarian endometriomas and allow a proper decision-making approach shared with the patient.IMPACT STATEMENTWhat is already known on this subject? Although endometriomas are common findings in infertile women, whether they should be surgically removed before an in vitro fertilisation (IVF) is a long-lasting debate, and current evidence does not offer a robust background to draw firm recommendations. What do the results of this study add? Women who underwent previous laparoscopic cystectomy for endometrioma need higher doses of gonadotrophins for ovarian stimulation and have a lower number of retrieved oocytes, compared with other types of infertility. Pregnancy and delivery rates remain comparable to other causes of infertility. What are the implications of these findings for clinical practice and/or further research? These pieces of information can help to make adequate counselling about reproductive outcomes for infertile women with ovarian endometriomas and allow a proper decision-making approach shared with the patient