Invasion of phagocytic Galectin 3 expressing macrophages in the diabetic brain disrupts vascular repair

The cellular events that dictate the repair of damaged vessels in the brain, especially in those with vascular risk factors such as diabetes, is poorly understood. Here, we dissected the role of resident microglia and infiltrative macrophages in determining the repair of ruptured cerebral microvessels. Using in vivo time-lapse imaging, gene expression analysis, and immunohistochemistry, we identified a unique population of phagocytic Galectin 3 (Gal3) expressing macrophages, distinct from resident microglia, which infiltrated and aggregated at the site of injury in diabetic mice and were associated with the elimination of microvessels. Depletion of these infiltrative macrophages in diabetic mice attenuated phagocytic activity and prevented the loss of blood vessels after injury. These findings highlight a previously unknown role for infiltrative Gal3 expressing macrophages in promoting vessel elimination after brain injury and provide impetus for future studies to determine whether depleting these cells can facilitate vascular repair in at risk populations.

LncRNA ZNF593-AS Alleviates Contractile Dysfunction in Dilated Cardiomyopathy

Rationale: Previously, we identified the human cardiac long non-coding RNAs (lncRNAs) profile in dilated cardiomyopathy (DCM) patients, among which ZNF593-AS, also named as RP11-96L14.7 and ENST00000448923.2, showed good conservation among species. Objective: We aim to elucidate the mechanism underlying lncRNA in DCM and DCM that lead to heart failure, which might provide new insights into the mechanisms of DCM and possible treatment strategies in the future. Methods and Results: lncRNA expression was measured by real-time PCR and in situ hybridization assays. Coding potential was verified by bioinformatic and biologic assays. Recombinant adeno-associated virus with cardiac specific promoter was used to deliver lncRNA in vivo, while cardiac structure and functions were assessed by echocardiography and catheter. Sarcomere shortening, calcium imaging, gene expression profiling, and pull-down assays were performed to investigate the underlying mechanisms. ZNF593-AS, which mainly localized in the cytoplasm of cardiomyocytes, was robustly decreased in the failing heart of DCM patients, as well as in phenylephrine-treated human cardiomyocytes. Overexpression of mmu-ZNF593-AS significantly improved transverse aortic constriction (TAC)-induced cardiac dysfunction in mice. Moreover, ZNF593-AS overexpression restored the aberrant Ca 2+ handling and contractility of cardiomyocytes from TAC-treated mice. Further, we found that ZNF593-AS acted as a guide RNA scaffold and recruited HNRNPC to ryanodine receptor type 2 (RYR2) mRNA, which in turn facilitated RYR2 mRNA stability, contributed to the improvement of cardiac Ca 2+ handling and contractile function in DCM. Conclusions: Our findings suggested that lncRNA-based therapeutics may protect against DCM.

The role of RNA uptake in platelet heterogeneity

SummaryThe role of platelets in regulating vascular homeostasis has expanded beyond mediation of haemostasis and thrombosis. The discovery of platelet RNA and the presence of subpopulations of platelets containing varying amounts of RNA suggest a role for platelet transcripts in vascular function. As the RNA in anucleated platelets is biologically functional and may transfer to other vascular cells, we hypothesised that platelet RNA diminishes over the lifespan of the platelet with diminishing platelet size due to horizontal cellular transfer. The purpose of this study is to determine if platelet RNA variance is the result of horizontal cellular transfer between platelets and other vascular cells. Utilising platelet sorting and RNA sequencing, we found that smaller platelets contained a more diverse set of transcripts than larger platelets. Further investigation using fluorescence imaging, gene expression analyses and in vitro and in vivo modelling revealed that platelets take up RNA from other vascular cells in a complex manner, revealing a dynamic role for platelets in modulating vascular homeostasis through bidirectional RNA transfer. The resultant RNA profile heterogeneity suggests unique functional roles for platelets dependent on size and complexity. This study expands our basic understanding of platelet function and heterogeneity and is the first to evaluate endogenous vascular RNA uptake and its relation to platelet processes. Our findings describe a novel endogenous phenomenon that can help elucidate the platelet’s role in these non-thrombotic and haemostatic fields, as well as present potential for diagnostic and therapeutic development.Supplementary Material to this article is available online at www.thrombosis-online.com.