Platelet-targeted gene therapy induces immune tolerance in hemophilia and beyond.

Blood platelets have unique storage and delivery capabilities. Platelets play fundamental roles in hemostasis, inflammatory reactions, and immune responses. Beyond their functions, platelets have been used as a target for gene therapy.

Pre-existing anti-factor VIII immunity alters therapeutic platelet-targeted factor VIII engraftment following busulfan conditioning through cytotoxic CD8 T cells.

Background: We previously demonstrated that busulfan preconditioning enabled sustained therapeutic platelet-derived factor VIII (FVIII) expression in naïve FVIII mice transplanted with 2bF8-transduced Sca-1 cells. However, in mice with pre-existing inhibitors, platelet-FVIII expression was lost.

Objective: In this study, we aimed to describe the mechanism of this platelet-FVIII loss.

Thromboelastometry assessment of hemostatic properties in various murine models with coagulopathy and the effect of factor VIII therapeutics.

Background: Rotational thromboelastometry (ROTEM) has been commonly used to assess the viscoelastic properties of the blood clotting process in the clinic for patients with a hemostatic or prothrombotic disorder.

Objective: To evaluate the capability of ROTEM in assessing hemostatic properties in whole blood from various mouse models with genetic bleeding or clotting disease and the effect of factor VIII (FVIII) therapeutics in FVIII mice.

Methods: Mice with a genetic deficiency in either a coagulation factor or a platelet glycoprotein were used in this study.

The impact of GPIbα on platelet-targeted FVIII gene therapy in hemophilia A mice with pre-existing anti-FVIII immunity.

Essentials Platelet-specific FVIII gene therapy is effective in hemophilia A mice even with inhibitors. The impact of platelet adherence via VWF/GPIbα binding on platelet gene therapy was investigated. GPIbα does not significantly affect platelet gene therapy of hemophilia A with inhibitors.

Platelet-Targeted Gene Therapy for Hemophilia.

Gene therapy is an attractive approach for disease treatment. Since platelets are abundant cells circulating in blood with the distinctive abilities of storage and delivery and fundamental roles in hemostasis and immunity, they could be a unique target for gene therapy of diseases. Recent studies have demonstrated that ectopic expression of factor VIII (FVIII) in platelets under control of the platelet-specific promoter results in FVIII storage together with its carrier protein von Willebrand factor (VWF) in α-granules and the phenotypic correction of hemophilia A.

Immune tolerance induced by platelet-targeted factor VIII gene therapy in hemophilia A mice is CD4 T cell mediated.

Unlabelled: Essentials The immune response is a significant concern in gene therapy. Platelet-targeted gene therapy can restore hemostasis and induce immune tolerance. CD4 T cell compartment is tolerized after platelet gene therapy.

Oncolytic Seneca Valley Virus: past perspectives and future directions.

Seneca Valley Virus isolate 001 (SVV-001) is an oncolytic RNA virus of the Picornaviridae family. It is also the first picornavirus discovered of the novel genus Senecavirus. SVV-001 replicates through an RNA intermediate, bypassing a DNA phase, and is unable to integrate into the host genome.

Targeting factor VIII expression to platelets for hemophilia A gene therapy does not induce an apparent thrombotic risk in mice.

Unlabelled: Essentials Platelet-Factor (F) VIII gene therapy is a promising treatment in hemophilia A. This study aims to evaluate if platelet-FVIII expression would increase the risk for thrombosis. Targeting FVIII expression to platelets does not induce or elevate thrombosis risk.

The Physiology of Eructation.

Eructation is composed of three independent phases: gas escape, upper barrier elimination, and gas transport phases. The gas escape phase is the gastro-LES inhibitory reflex that causes transient relaxation of the lower esophageal sphincter, which is activated by distension of stretch receptors of the proximal stomach. The upper barrier elimination phase is the transient relaxation of the upper esophageal sphincter along with airway protection.

The important role of von Willebrand factor in platelet-derived FVIII gene therapy for murine hemophilia A in the presence of inhibitory antibodies.

Background: Our previous studies have demonstrated that targeting FVIII expression to platelets results in FVIII storage together with von Willebrand factor (VWF) in platelet α-granules and that platelet-derived FVIII (2bF8) corrects the murine hemophilia A phenotype even in the presence of high-titer anti-FVIII inhibitory antibodies (inhibitors).

Objective: To explore how VWF has an impact on platelet gene therapy for hemophilia A with inhibitors.

Methods: 2bF8 transgenic mice in the FVIII(-/-) background (2bF8(tg+/-) F8(-/-) ) with varying VWF phenotypes were used in this study.

Integrin binding by Borrelia burgdorferi P66 facilitates dissemination but is not required for infectivity.

P66, a Borrelia burgdorferi surface protein with porin and integrin-binding activities, is essential for murine infection. The role of P66 integrin-binding activity in B. burgdorferi infection was investigated and found to affect transendothelial migration.

Gain of Function Mutations of PIK3CD as a Cause of Primary Sclerosing Cholangitis.

Gain of function (GOF) mutation in the p110δ catalytic subunit of the phosphatidylinositol-3-OH kinase (PIK3CD) is the cause of a primary immunodeficiency (PID) characterized by recurrent sinopulmonary infections and lymphoproliferation. We describe a family of two adults and three children with GOF mutation in PIK3CD, all with recurrent sinopulmonary infections and varied infectious and non-infectious complications. The two adults have Primary Sclerosing Cholangitis (PSC) without evidence of Cryptosporidium parvum infection and have required liver transplantation.

Platelet-targeted gene therapy with human factor VIII establishes haemostasis in dogs with haemophilia A.

It is essential to improve therapies for controlling excessive bleeding in patients with haemorrhagic disorders. As activated blood platelets mediate the primary response to vascular injury, we hypothesize that storage of coagulation Factor VIII within platelets may provide a locally inducible treatment to maintain haemostasis for haemophilia A. Here we show that haematopoietic stem cell gene therapy can prevent the occurrence of severe bleeding episodes in dogs with haemophilia A for at least 2.

Platelet gene therapy by lentiviral gene delivery to hematopoietic stem cells restores hemostasis and induces humoral immune tolerance in FIX(null) mice.

Here, we developed a clinically translatable platelet gene therapy approach for hemophilia B. Platelet-targeted FIX (2bF9) expression was introduced by transplantation of hematopoietic stem cells (HSCs) transduced with 2bF9 lentivirus (LV). Sustained therapeutic levels of platelet-FIX expression were obtained in FIX(null) mice that received 2bF9 LV-transduced HSCs.

Dendritic cells, viruses, and the development of atopic disease.

Dendritic cells are important residents of the lung environment. They have been associated with asthma and other inflammatory diseases of the airways. In addition to their antigen-presenting functions, dendritic cells have the ability to modulate the lung environment to promote atopic disease.

Development of atopy by severe paramyxoviral infection in a mouse model.

Background: Atopic diseases have been increasing in prevalence, yet the initial inciting events that lead to atopy are not understood. Paramyxoviral infections have been suggested to play a role; however, much of these data are correlative.

Objective: To determine whether exposure to a nonviral antigen during a paramyxoviral infection is sufficient to drive IgE production against the bystander antigen and whether clinical disease against this antigen would result.

Targeting platelet GPIbalpha transgene expression to human megakaryocytes and forming a complete complex with endogenous GPIbbeta and GPIX.

Bernard-Soulier Syndrome (BSS) is a severe congenital platelet disorder that results from a deficiency of the platelet membrane glycoprotein (GP) Ib/IX complex that is composed of four subunits (GPIbalpha, GPIbbeta, GPIX, and GPV). Mutations in either GPIbalpha, GPIbbeta, or GPIX can result in BSS with many of the known mutations occurring in GPIbalpha. In this study, we have developed a gene therapy strategy to express hemagglutinin (HA)-tagged GPIbalpha in megakaryocytes and potentially correct a hereditary deficiency.

Sudden death in congenital heart disease.

Sudden cardiac death is a common mechanism of demise in association with congenital cardiac abnormalities. The varied mechanisms may include failure of the transitional circulation, arrhythmias, postoperative or perioperative complications in the neonate and coronary ischaemia, arrhythmias, sepsis, thrombosis, or pulmonary hypertensive crisis in the older child. Knowledge of the natural history of unoperated and operated forms of congenital heart disease and long term follow up with the detection and treatment of underlying hemodynamic abnormalities should improve outcomes.

Glucose sensor evaluation of glycemic instability in pediatric type 1 diabetes mellitus.

Maintaining blood glucose (BG) levels within the target range can be an elusive goal in children with type 1 diabetes mellitus (DM). To identify factor(s) that may contribute to glycemic instability, we analyzed the Continuous Glucose Monitoring System (CGMS) (Medtronic MiniMed, Northridge, CA) profiles of a group of children with type 1 DM and a history of frequent BG fluctuations and hypoglycemia. A total of 30 (17 girls, 13 boys) pediatric patients with a history of frequent BG fluctuations and hypoglycemia (mean age, 10.

Delayed hemolytic transfusion reaction/hyperhemolysis syndrome in children with sickle cell disease.

Objective: Alloimmunization in patients with sickle cell disease (SCD) has a reported incidence of 5% to 36%. One complication of alloimmunization is delayed hemolytic transfusion reaction/hyperhemolysis (DHTR/H) syndrome, which has a reported incidence of 11%. In patients with SCD, clinical findings in DHTR/H syndrome occur approximately 1 week after the red blood cell (RBC) transfusion and include the onset of increased hemolysis associated with pain and profound anemia.

Expression of human factor VIII under control of the platelet-specific alphaIIb promoter in megakaryocytic cell line as well as storage together with VWF.

Hemophilia A, which results in defective or deficient factor VIII (FVIII) protein, is one of the genetic diseases that has been addressed through gene therapy trials. FVIII synthesis does not occur in normal megakaryocytes. In hemophilia patients who have inhibitors to FVIII activity, megakaryocytes could be a protected site of FVIII synthesis and subsequent release.