The multifaceted roles of perlecan in fibrosis

Perlecan, or heparan sulfate proteoglycan 2 (HSPG2), is a ubiquitous heparan sulfate proteoglycan that has major roles in tissue and organ development and wound healing by orchestrating the binding and signaling of mitogens and morphogens to cells in a temporal and dynamic fashion. In this review, its roles in fibrosis are reviewed by drawing upon evidence from tissue and organ systems that undergo fibrosis as a result of an uncontrolled response to either inflammation or traumatic cellular injury leading to an over production of a collagen-rich extracellular matrix. This review focuses on examples of fibrosis that occurs in lung, liver, kidney, skin, kidney, neural tissues and blood vessels and its link to the expression of perlecan in that particular organ system

Methods for Monitoring Matrix-Induced Autophagy.

A growing body of research demonstrates modulation of autophagy by a variety of matrix constituents, including decorin, endorepellin, and endostatin. These matrix proteins are both pro-autophagic and anti-angiogenic. Here, we detail a series of methods to monitor matrix-induced autophagy and its concurrent effects on angiogenesis. We first discuss cloning and purifying proteoglycan fragment and core proteins in the laboratory and review relevant techniques spanning from cell culture to treatment with these purified proteoglycans in vitro and ex vivo. Further, we cover protocols in monitoring autophagic progression via morphological and microscopic characterization, biochemical western blot analysis, and signaling pathway investigation. Downstream angiogenic effects using in vivo approaches are then discussed using wild-type mice and the GFP-LC3 transgenic mouse model. Finally, we explore matrix-induced mitophagy via monitoring changes in mitochondrial DNA and permeability

HMG-CoA reductase inhibitors: Atorvastatin and simvastatin. Hypocholesterolemic mechanisms of action in the guinea pig

Coronary heart disease (CHD) is the number one cause of mortality and morbidity in the United States. Elevated levels of plasma cholesterol are considered a risk factor for CHD. Thus, reducing plasma cholesterol is associated with decreases in CHD risk. HMG-CoA reductase inhibitors or statins are pharmacological agents that lower total plasma cholesterol.^ The purpose of these studies was to determine the specific mechanisms by which atorvastatin (AT) and simvastatin (Sim), two HMG-CoA reductase inhibitors, lower plasma cholesterol. Guinea pigs were used as the animal model because their lipoprotein profile and responses to drugs are similar to humans.^ Guinea pigs were fed hypercholesterolemic diets with different concentrations of AT or Sim. AT and Sim treatment resulted in a dose dependent reduction of plasma LDL cholesterol and apo B concentrations. AT treatment yielded cholesteryl ester depleted LDL, while simvastatin resulted in LDL with higher triacylglycerols. In addition, both drugs were equally effective in decreasing in vitro LDL susceptibility to oxidation and cholesteryl ester transfer protein activity suggesting an important effect of statins in the intravascular processing of lipoproteins.^ Compared to control animals, AT and Sim treated groups had higher number of hepatic apo B/E receptors and faster LDL fractional catabolic rate. In addition, AT treatment resulted in the secretion of less number of VLDL particles suggesting that AT not only accelerated LDL clearance, but also affected VLDL synthesis.^ Simvastatin treatment had no effect on hepatic HMG-CoA reductase mRNA abundance. However, after guinea pigs were fasted for 6-18 h, Sim caused an up-regulation of enzyme activity that might be related to activation of existing protein or protein stabilization once Sim was removed from the active site of the enzyme. In contrast, AT treatment resulted in an increase in HMG-CoA reductase mRNA and no effect on enzyme activity even after 18h of fasting, which suggests that AT continued bound to the enzyme.^ From these studies we conclude that although AT and Sim are equally efficacious in reducing plasma cholesterol, there are important differences between statins in the molecular and metabolic regulation of hepatic enzymes and lipoprotein metabolism.

Spatial Transcriptional Mapping Reveals Site-Specific Pathways Underlying Human Atherosclerotic Plaque Rupture

Background: Atherosclerotic plaque ruptures, triggered by blood flow–associated biomechanical forces, cause most myocardial infarctions and strokes. Objectives: This study aims to investigate the exact location and underlying mechanisms of atherosclerotic plaque ruptures, identifying therapeutic targets against cardiovascular events. Methods: Histology, electron microscopy, bulk and spatial RNA sequencing on human carotid plaques were studied in proximal, most stenotic, and distal regions along the longitudinal blood flow direction. Genome-wide association studies were used to examine heritability enrichment and causal relationships of atherosclerosis and stroke. Associations between top differentially expressed genes (DEGs) and preoperative and postoperative cardiovascular events were examined in a validation cohort. Results: In human carotid atherosclerotic plaques, ruptures predominantly occurred in the proximal and most stenotic regions but not in the distal region. Histologic and electron microscopic examination showed that proximal and most stenotic regions exhibited features of plaque vulnerability and thrombosis. RNA sequencing identified DEGs distinguishing the proximal and most stenotic regions from the distal region which were deemed as most relevant to atherosclerosis-associated diseases as shown by heritability enrichment analyses. The identified pathways associated with the proximal rupture-prone regions were validated by spatial transcriptomics, firstly in human atherosclerosis. Of the 3 top DEGs, matrix metallopeptidase 9 emerged particularly because Mendelian randomization suggested that its high circulating levels were causally associated with atherosclerosis risk. Conclusions: Our findings show plaque site–specific transcriptional signatures associated with proximal rupture-prone regions of carotid atherosclerotic plaques. This led to the geographical mapping of novel therapeutic targets, such as matrix metallopeptidase 9, against plaque rupture.</p