Role of allogeneic placental tissues in penile inversion vaginoplasty.

Background: The role of allogeneic placental tissue (APT) in genital gender-affirming surgery (GAS) is not well understood. Penile inversion vaginoplasty (PIV), the most common genital GAS, often results in tissue healing- or wound-related complications, including scarring and neovaginal stenosis. Surgical reoperation and revision vaginoplasty are common. The aim of this study was to evaluate the contribution of APT to postoperative outcomes in PIV. Methods: The authors performed a retrospective analysis of consecutive adult patients undergoing primary PIV during a 6-year period (September 1, 2014 to September 1, 2020). Subjects receiving intraoperative application of an APT biomaterial were compared to those undergoing primary PIV without APT. Postoperative outcomes-including wound healing morbidity and reoperation-were compared between groups. Short- and long-term complications were classified using Clavien-Dindo. Results: A total of 182 primary PIV cases were reviewed (115 conventional PIV; 67 PIV-APT). The postoperative follow-up time for the population averaged 12.7 months. All-cause and wound related complications were significantly lower amongst PIV-APT patients when compared to conventional PIV (P=0.002 and P=0.004, respectively). The rate of long-term complications was significantly lower in PIV-APT subjects: prolonged pain (P=0.001), prolonged swelling (P=0.047), and neovaginal stenosis (P<0.001). The PIV-APT group required significantly less reoperation for vaginal depth enhancement (P=0.007). Conclusions: Though its use in urogenital reconstruction has been limited, this study indicates that the placement of APT during PIV significantly lowered the risk of complications associated with poor wound healing. This supports a novel use for placental tissues in reducing complications in genital GAS.

P66 is a bacterial mimic of CD47 that binds the anti-phagocytic receptor SIRPα and facilitates macrophage evasion by Borrelia burgdorferi.

Innate immunity, the first line of defense against pathogens, relies on efficient elimination of invading agents by phagocytes. In the co-evolution of host and pathogen, pathogens developed mechanisms to dampen and evade phagocytic clearance. Here, we report that bacterial pathogens can evade clearance by macrophages through mimicry at the mammalian anti-phagocytic "don't eat me" signaling axis between CD47 (ligand) and SIRPα (receptor). We identified a protein, P66, on the surface of Borrelia burgdorferi that, like CD47, is necessary and sufficient to bind the macrophage receptor SIRPα. Expression of the gene encoding the protein is required for bacteria to bind SIRPα or a high-affinity CD47 reagent. Genetic deletion of p66 increases phagocytosis by macrophages. Blockade of P66 during infection promotes clearance of the bacteria. This study demonstrates that mimicry of the mammalian anti-phagocytic protein CD47 by B. burgdorferi inhibits macrophage-mediated bacterial clearance. Such a mechanism has broad implications for understanding of host-pathogen interactions and expands the function of the established innate immune checkpoint receptor SIRPα. Moreover, this report reveals P66 as a novel therapeutic target in the treatment of Lyme Disease.

SIRPα controls CD47-dependent platelet clearance in mice and humans.

Over the last decade, more data has revealed that increased surface expression of the "don't eat me" CD47 protein on cancer cells plays a role in immune evasion and tumor progression, with CD47 blockade emerging as a new therapy in immuno-oncology. CD47 is critical in regulating cell homeostasis and clearance, as binding of CD47 to the inhibitory receptor SIRPα can prevent phagocytosis and macrophage-mediated cell clearance. The purpose of this study was to examine the role of the CD47-SIRPα signal in platelet homeostasis and clearance. Therapeutic reagents targeting the CD47-SIRPα axis are very promising for treatment of hematologic malignancies and solid tumors, but lead to transient anemia or thrombocytopenia in a subset of patients. We found that platelet homeostatic clearance is regulated through the CD47-SIRPα axis and that therapeutic blockade to disrupt this interaction in mice and in humans has a significant impact on platelet levels. Furthermore, we identified genetic variations at the SIRPA locus that impact platelet levels in humans such that higher SIRPA gene expression is associated with higher platelet levels. SIRPA expression at either end of the normal range may affect clinical outcomes of treatment with anti-CD47 therapy.