Granzyme K : a novel contributor in cardiac allograft vasculopathy

Background - A major factor limiting survival for patients that have undergone cardiac transplantation is cardiac allograft vasculopathy (CAV). CAV is a fibroproliferative inflammatory form of vascular rejection mediated by immune cells and which is initiated upon damage to the graft endothelium and medial smooth muscle cells (SMC). Granzymes are a family of five serine proteases in humans. Granzymes have been shown to exert roles in cell death, endothelial dysfunction, inflammation and matrix remodeling. Granzyme K (GzmK) specifically can promote endothelial dysfunction and the production of inflammatory mediators IL-1β, IL-6, and monocyte chemotactic protein-1. As such, we hypothesized that GzmK contributes to CAV. Methods - An infrarenal aortic interposition graft was completed across a complete major histocompatibility complex (MHC)-mismatch with recipients being either wildtype or GzmK-KO mice. Allografts were then assessed for CAV severity and compared to human CAV samples. The effects of GzmK on human SMC were also assessed in vitro. Given that atherosclerosis shares similar underlying mechanisms to CAV, GzmK deposition was also characterized in atherosclerosis. Results - Human CAV samples demonstrated increased neointimal GzmK deposition as compared to unaffected native coronaries (p= 0.017). GzmK primarily localized to the medial and neointimal layers. Similar deposition patterns were observed in murine transplants. When the role of GzmK was examined, GzmK deficiency resulted in reduced CAV with less neointima formation (p=0.019) and less luminal obstruction (p<0.0163). GzmK deficiency also had significantly less cellular proliferation as measured by Ki67 (p=0.026) while apoptosis (as measured by cleaved caspase 3) was unaffected (p=0.711). In vitro, GzmK lacked cytotoxicity on SMC whereas it increased cellular proliferation by 30% (p=0.038). Immunofluorescence co-localized GzmK with macrophages and lymphocytes while GzmK deposition was also observed in GzmK-KO recipients indicating that it is potentially graft derived. Conclusion – GzmK contributes to CAV with GzmK potentially arising from recipient and graft derived sources. GzmK may serve as a novel therapeutic target in CAVMedicine, Faculty ofExperimental Medicine, Division ofMedicine, Department ofGraduat

Cardio-centric hemodynamic management improves spinal cord oxygenation and mitigates hemorrhage in acute spinal cord injury

Clinical neuroprotective strategies for acute spinal cord injury (SCI) have largely overlooked the heart. Here the authors show cardiac contractility is immediately impaired in a porcine model of T2 SCI, and cardio-centric treatment with dobutamine optimizes cord oxygenation and mitigates haemorrhage

Recombinant Decorin Fusion Protein Attenuates Murine Abdominal Aortic Aneurysm Formation and Rupture

Abstract Decorin (DCN) is a small-leucine rich proteoglycan that mediates collagen fibrillogenesis, organization, and tensile strength. Adventitial DCN is reduced in abdominal aortic aneurysm (AAA) resulting in vessel wall instability thereby predisposing the vessel to rupture. Recombinant DCN fusion protein CAR-DCN was engineered with an extended C-terminus comprised of CAR homing peptide that recognizes inflamed blood vessels and penetrates deep into the vessel wall. In the present study, the role of systemically-administered CAR-DCN in AAA progression and rupture was assessed in a murine model. Apolipoprotein E knockout (ApoE-KO) mice were infused with angiotensin II (AngII) for 28 days to induce AAA formation. CAR-DCN or vehicle was administrated systemically until day 15. Mortality due to AAA rupture was significantly reduced in CAR-DCN-treated mice compared to controls. Although the prevalence of AAA was similar between vehicle and CAR-DCN groups, the severity of AAA in the CAR-DCN group was significantly reduced. Histological analysis revealed that CAR-DCN treatment significantly increased DCN and collagen levels within the aortic wall as compared to vehicle controls. Taken together, these results suggest that CAR-DCN treatment attenuates the formation and rupture of Ang II-induced AAA in mice by reinforcing the aortic wall