Cardiovascular Disease, Endothelial Cell Gene Expression, and Renal Dysfunction in Insulin Resistant, Hyperlipidemic Swine

Globally, the prevalence of insulin resistant (IR), type-2 diabetes mellitus (DM) is increasing. Both IR and DM are associated with an increase in cardiovascular events and renal pathology. The underlying cause for this increase is, as yet, not completely understood. A thoroughly characterized model is needed to identify mechanisms connecting insulin resistance with cardiovascular and renal disease. Through selective breeding we have produced hyperinsulinemic pigs that develop hypercholesterolemia when fed a high fat diet. A subgroup of these pigs develops severe and diffuse proximal and distal abdominal aorta and coronary artery atherosclerosis compared to the other group which has moderate disease. Through aortic endothelial cell gene expression studies we have identified three genes (MERP-1, RABGAP1L, COL12A1) that are uniquely expressed in the atherosclerotic endothelium of the severe disease group. Additionally, a subgroup of the pigs develops renal histopathology that mirrors the phenotype of an insulin resistant/diabetic nephropathy when albuminuria is present. All pigs have been monitored over the course of one year on a high fat, high sodium diet for weight, backfat, blood pressure, insulin sensitivity, total and LDL cholesterol, triglycerides, oxidized LDL, fructosamine, inflammatory makers, and aldosterone. The goals of this proposal were to characterize this pig model with regards to 1- presence and severity of coronary and aortic atherosclerosis and its association with markers of oxidative stress, 2-changes in endothelial cell gene expression as it relates to the severity of aortic atherosclerosis, and 3-extent of renal pathology and its resemblance to human diabetic renal disease. This will support the long range goal of this laboratory, which is to provide the scientific community with a well-characterized, useful animal model of insulin resistance and/or type-2 diabetes, which develops human-like coronary and aortic atherosclerosis and IR/diabetic like nephropathy

ARFI Imaging for Noninvasive Material Characterization of Atherosclerosis Part II: Toward In Vivo Characterization

Seventy percent of cardiovascular disease (CVD) deaths are attributed to atherosclerosis. Despite their clinical significance, nonstenotic atherosclerotic plaques are not effectively detected by conventional atherosclerosis imaging methods. Moreover, conventional imaging methods are insufficient for describing plaque composition, which is relevant to cardiovascular risk assessment. Atherosclerosis imaging technologies capable of improving plaque detection and stratifying cardiovascular risk are needed. Acoustic Radiation Force Impulse (ARFI) ultrasound, a novel imaging method for noninvasively differentiating the mechanical properties of tissue, is demonstrated for in vivo detection of nonstenotic plaques and plaque material assessment in this pilot investigation. In vivo ARFI imaging was performed on four iliac arteries: 1) of a normocholesterolemic pig with no atherosclerosis as a control, 2) of a familial hypercholesterolemic pig with diffuse atherosclerosis, 3) of a normocholesterolemic pig fed a high-fat diet with early atherosclerotic plaques and 4) of a familial hypercholesterolemic pig with diffuse atherosclerosis and a small, minimally-occlusive plaque. ARFI results were compared to spatially matched immunohistochemistry, showing correlations between elastin and collagen content and ARFI-derived peak displacement and recovery time parameters. Faster recoveries from ARFI-induced peak displacements and smaller peak displacements were observed in areas of higher elastin and collagen content. Importantly, spatial correlations between tissue content and ARFI results were consistent and observable in both large and highly evolved as well as small plaques. ARFI imaging successfully distinguished nonstenotic plaques, while conventional B-Mode ultrasound did not. This work validates the potential relevance of ARFI imaging as a noninvasive imaging technology for in vivo detection and material assessment of atherosclerotic plaques

Global measurement of coagulation in plasma from normal and haemophilia dogs using a novel modified thrombin generation test – Demonstrated in vitro and ex vivo

Canine models of severe haemophilia resemble their human equivalents both regarding clinical bleeding phenotype and response to treatment. Therefore pre-clinical studies in haemophilia dogs have allowed researchers to make valuable translational predictions regarding the potency and efficacy of new anti-haemophilia drugs (AHDs) in humans. To refine in vivo experiments and reduce number of animals, such translational studies are ideally preceded by in vitro prediction of compound efficacy using a plasma based global coagulation method. One such widely used method is the thrombin generation test (TGT). Unfortunately, commercially available TGTs are incapable of distinguishing between normal and haemophilia canine plasma, and therefore in vitro prediction using TGT has so far not been possible in canine plasma material

Severe Hemophilia A in a Male Old English Sheep Dog with a C→T Transition that Created a Premature Stop Codon in Factor VIII

Animals with hemophilia are models for gene therapy, factor replacement, and inhibitor development in humans. We have actively sought dogs with severe hemophilia A that have novel factor VIII mutations unlike the previously described factor VIII intron 22 inversion. A male Old English Sheepdog with recurrent soft-tissue hemorrhage and hemarthrosis was diagnosed with severe hemophilia A (factor VIII activity less than 1% of normal). We purified genomic DNA from this dog and ruled out the common intron 22 inversion; we then sequenced all 26 exons. Comparing the results with the normal canine factor VIII sequence revealed a C→T transition in exon 12 of the factor VIII gene that created a premature stop codon at amino acid 577 in the A2 domain of the protein. In addition, 2 previously described polymorphisms that do not cause hemophilia were present at amino acids 909 and 1184. The hemophilia mutation creates a new TaqI site that facilitates rapid genotyping of affected offspring by PCR and restriction endonuclease analyses. This mutation is analogous to the previously described human factor VIII mutation at Arg583, which likewise is a CpG dinucleotide transition causing a premature stop codon in exon 12. Thus far, despite extensive treatment with factor VIII, this dog has not developed neutralizing antibodies (‘inhibitors’) to the protein. This novel mutation in a dog gives rise to severe hemophilia A analogous to a mutation seen in humans. This model will be useful for studies of the treatment of hemophilia

Soy Phosphatidylinositol–Containing Lipid Nanoparticle Prolongs the Plasma Survival and Hemostatic Efficacy of B-domain–Deleted Recombinant Canine Factor VIII in Hemophilia A Dogs

Soy phosphatidylinositol (PI) containing lipid nanoparticles prolong plasma survival, improve hemostatic efficacy, and decrease immunogenicity of human B-domain deleted Factor VIII (BDD FVIII) in Hemophilia A (HA) mice. We hypothesize that PI associated BDD FVIII is more potent than the free protein, and using mathematical modeling, have projected that PI associated BDD FVIII could be used for once-weekly prophylactic dosing in patients. To facilitate translation to the clinic, comparative plasma survival and ex vivo efficacy of PI associated recombinant canine FVIII (PI-rcFVIII) were evaluated in HA dogs. 2 HA dogs were administered a 50 U/kg iv dose of free or PI-rcFVIII. rcFVIII activity measurements and ex vivo efficacy analyses like whole blood clotting time (WBCT) and thromboelastography (TEG) were conducted on recovered plasma and whole blood samples. PI association decreased clearance (~25%) and increased plasma exposure (~1.4 fold) of rcFVIII. PI-rcFVIII treated animals had prolonged improvements in WBCTs and TEG parameters compared to free rcFVIII treated animals. Since rcFVIII is a BDD form of FVIII, these studies provide proof-of-principle that observations with human BDD FVIII in mice translate to higher animal species. Additionally, PI-rcFVIII has potential applications in canine HA management and as a bypass therapy in inhibitor-positive HA patients

Experimental Validation of ARFI Surveillance of Subcutaneous Hemorrhage (ASSH) Using Calibrated Infusions in a Tissue-Mimicking Model and Dogs

Acoustic radiation force impulse (ARFI) Surveillance of Subcutaneous Hemorrhage (ASSH) has been previously demonstrated to differentiate bleeding phenotype and responses to therapy in dogs and humans, but to date, the method has lacked experimental validation. This work explores experimental validation of ASSH in a poroelastic tissue-mimic and in vivo in dogs. The experimental design exploits calibrated flow rates and infusion durations of evaporated milk in tofu or heparinized autologous blood in dogs. The validation approach enables controlled comparisons of ASSH-derived bleeding rate (BR) and time to hemostasis (TTH) metrics. In tissue-mimicking experiments, halving the calibrated flow rate yielded ASSH-derived BRs that decreased by 44% to 48%. Furthermore, for calibrated flow durations of 5.0 minutes and 7.0 minutes, average ASSH-derived TTH was 5.2 minutes and 7.0 minutes, respectively, with ASSH predicting the correct TTH in 78% of trials. In dogs undergoing calibrated autologous blood infusion, ASSH measured a 3-minute increase in TTH, corresponding to the same increase in the calibrated flow duration. For a measured 5% decrease in autologous infusion flow rate, ASSH detected a 7% decrease in BR. These tissue-mimicking and in vivo preclinical experimental validation studies suggest the ASSH BR and TTH measures reflect bleeding dynamics

Phase II prospective open-label trial of recombinant interleukin-11 in women with mild von Willebrand disease and refractory menorrhagia

Lack of effective treatment for menorrhagia is the greatest unmet healthcare need in women with von Willebrand disease (VWD). We conducted a single-centre phase II clinical trial to determine efficacy and safety of recombinant IL-11 (rhIL-11, Neumega®) given subcutaneously for up to seven days during six consecutive menstrual cycles each in seven women with mild VWD and menorrhagia refractory to haemostatic or hormonal agents. rhIL-11 reduced menstrual bleeding severity as measured by pictorial blood assessment chart (PBAC) ≥50% (to 0.05. Platelet VWF mRNA expression by quantitative PCR increased mean four-fold (1.0–13.5). rhIL-11 was well tolerated with grade 1 or less fluid retention, flushing, conjunctival erythema, and local bruising. In summary, rhIL-11 reduces menorrhagia safely and warrants further study

Phase II Prospective Open-Label Trial of Recombinant Interleukin-11 in DDAVP-Unresponsive Von Willebrand Disease and Mild or Moderate Hemophilia A

Desmopressin (DDAVP) is the treatment of choice in those with mild von Willebrand disease (VWD), yet 20% are unresponsive to DDAVP, and among the 80% who respond, the response is transient, as endothelial stores are depleted after 3 days. We, therefore, conducted a single-center Phase II clinical trial to determine safety and biologic efficacy of recombinant interleukin-11 (rhIL-11, Neumega®) in patients with VWD unresponsive or allergic to DDAVP, or mild or moderate hemophilia A (HA). Increases in VWF:RCo were observed by 48 hours after rhIL-11, with a 1.54-fold increase by day 4, 1.30-fold in VWD and 1.73-fold in HA. Similarly, by 48 hours, increases in VIII:C were observed, with a 1.65-fold increase by day 4, 1.86-fold in VWD and 1.48-fold in HA. Platelet VWFmRNA expression by qPCR increased 0.81-fold but did not correlate with plasma VWF:Ag responses. rhIL-11 was well tolerated, with grade 1 or less fluid retention, flushing, conjunctival erythema, except for transient grade 3 hyponatremia in one subject after excess fluid intake for diabetic hyperglycemia, which resolved with fluid restriction. In summary, rhIL-11 increases VWF levels in 2 of 4 DDAVP-unresponsive or allergic VWD and F.VIII levels in 4 of 5 mild or moderate hemophilia A subjects, suggesting its potential use in treatment of these disorders

Porcine and Canine von Willebrand Factor and von Willebrand Disease: Hemostasis, Thrombosis, and Atherosclerosis Studies

Use of animal models of inherited and induced von Willebrand factor (VWF) deficiency continues to advance the knowledge of VWF-related diseases: von Willebrand disease (VWD), thrombotic thrombocytopenic purpura (TTP), and coronary artery thrombosis. First, in humans, pigs, and dogs, VWF is essential for normal hemostasis; without VWF bleeding events are severe and can be fatal. Second, the ADAMTS13 cleavage site is preserved in all three species suggesting all use this mechanism for normal VWF multimer processing and that all are susceptible to TTP when ADAMTS13 function is reduced. Third, while the role of VWF in atherogenesis is debated, arterial thrombosis complicating atherosclerosis appears to be VWF-dependent. The differences in the VWF gene and protein between humans, pigs, and dogs are relatively few but important to consider in the design of VWF-focused experiments. These homologies and differences are reviewed in detail and their implications for research projects are discussed. The current status of porcine and canine VWD are also reviewed as well as their potential role in future studies of VWF-related disorders of hemostasis and thrombosis

Oral Tolerance Induction in Hemophilia B Dogs Fed with Transplastomic Lettuce

Anti-drug antibodies in hemophilia patients substantially complicate treatment. Their elimination through immune tolerance induction (ITI) protocols poses enormous costs, and ITI is often ineffective for factor IX (FIX) inhibitors. Moreover, there is no prophylactic ITI protocol to prevent anti-drug antibody (ADA) formation. Using general immune suppression is problematic. To address this urgent unmet medical need, we delivered antigen bioencapsulated in plant cells to hemophilia B dogs. Commercial-scale production of CTB-FIX fusion expressed in lettuce chloroplasts was done in a hydroponic facility. CTB-FIX (∼1 mg/g) in lyophilized cells was stable with proper folding, disulfide bonds, and pentamer assembly after 30-month storage at ambient temperature. Robust suppression of immunoglobulin G (IgG)/inhibitor and IgE formation against intravenous FIX was observed in three of four hemophilia B dogs fed with lyophilized lettuce cells expressing CTB-FIX. No side effects were detected after feeding CTB-FIX-lyophilized plant cells for >300 days. Coagulation times were markedly shortened by intravenous FIX in orally tolerized treated dogs, in contrast to control dogs that formed high-titer antibodies to FIX. Commercial-scale production, stability, prolonged storage of lyophilized cells, and efficacy in tolerance induction in a large, non-rodent model of human disease offer a novel concept for oral tolerance and low-cost production and delivery of biopharmaceuticals