Modulation of Macrophage Activation State Protects Tissue from Necrosis during Critical Limb Ischemia in Thrombospondin-1-Deficient Mice

International audienceBACKGROUND: Macrophages, key regulators of healing/regeneration processes, strongly infiltrate ischemic tissues from patients suffering from critical limb ischemia (CLI). However pro-inflammatory markers correlate with disease progression and risk of amputation, suggesting that modulating macrophage activation state might be beneficial. We previously reported that thrombospondin-1 (TSP-1) is highly expressed in ischemic tissues during CLI in humans. TSP-1 is a matricellular protein that displays well-known angiostatic properties in cancer, and regulates inflammation in vivo and macrophages properties in vitro. We therefore sought to investigate its function in a mouse model of CLI. METHODS AND FINDINGS: Using a genetic model of tsp-1(-/-) mice subjected to femoral artery excision, we report that tsp-1(-/-) mice were clinically and histologically protected from necrosis compared to controls. Tissue protection was associated with increased postischemic angiogenesis and muscle regeneration. We next showed that macrophages present in ischemic tissues exhibited distinct phenotypes in tsp-1(-/-) and wt mice. A strong reduction of necrotic myofibers phagocytosis was observed in tsp-1(-/-) mice. We next demonstrated that phagocytosis of muscle cell debris is a potent pro-inflammatory signal for macrophages in vitro. Consistently with these findings, macrophages that infiltrated ischemic tissues exhibited a reduced postischemic pro-inflammatory activation state in tsp-1(-/-) mice, characterized by a reduced Ly-6C expression and a less pro-inflammatory cytokine expression profile. Finally, we showed that monocyte depletion reversed clinical and histological protection from necrosis observed in tsp-1(-/-) mice, thereby demonstrating that macrophages mediated tissue protection in these mice. CONCLUSION: This study defines targeting postischemic macrophage activation state as a new potential therapeutic approach to protect tissues from necrosis and promote tissue repair during CLI. Furthermore, our data suggest that phagocytosis plays a crucial role in promoting a deleterious intra-tissular pro-inflammatory macrophage activation state during critical injuries. Finally, our results describe TSP-1 as a new relevant physiological target during critical leg ischemia

Formal Verification of Software-Intensive Systems Architectures Described with Piping and Instrumentation Diagrams

International audienceSocio-technical systems are increasingly becoming software-intensive. The challenge now is to design the architecture of such software-intensive systems for guaranteeing not only its correctness, but also the correctness of its implementation. In social-technical systems, the architecture (including software and physical elements) is described in terms of Piping and Instrumentation Diagrams (P&ID). The design of these P&ID is still considered an art for which no rigorous design support exists. In order to detect and eliminate architectural design flaws, this paper proposes a formal-based automated approach for the verification of the essential architecture “total correctness” properties, i.e. compatibility, completeness, consistency, and correctness. This approach is based on the definition of an architectural style for P&ID design in Alloy. We use MDE to automatically generate Alloy models from a P&ID and check their compatibility with the style and its completeness, consistency, and correctness properties. Our approach is presented through an industrial case study: the system of storage and production of freshwater for a ship

Lysyl oxidase secreted by tumour endothelial cells promotes angiogenesis and metastasis

Background: Molecules that are highly expressed in tumour endothelial cells (TECs) may be candidates for specifically targeting TECs. Using DNA microarray analysis, we found that the lysyl oxidase (LOX) gene was upregulated in TECs compared with its expression in normal endothelial cells (NECs). LOX is an enzyme that enhances invasion and metastasis of tumour cells. However, there are no reports on the function of LOX in isolated TECs. Methods: TECs and NECs were isolated to investigate LOX function in TECs. LOX inhibition of in vivo tumour growth was also assessed using beta-aminopropionitrile (BAPN). Results: LOX expression was higher in TECs than in NECs. LOX knockdown inhibited cell migration and tube formation by TECs, which was associated with decreased phosphorylation of focal adhesion kinase (Tyr 397). Immunostaining showed high LOX expression in human tumour vessels in vivo. Tumour angiogenesis and micrometastasis were inhibited by BAPN in an in vivo tumour model. Conclusion: LOX may be a TEC marker and a possible therapeutic target for novel antiangiogenic therapy