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The quantification of tunica media thickness in histological cross sections is a ubiquitous exercise in cardiopulmonary research, yet the methods for quantifying medial wall thickness have never been rigorously examined with modern image analysis tools. As a result, inaccurate and cumbersome manual measurements of discrete wall regions along the vessel periphery have become common practice for wall thickness quantification. The aim of this study is to introduce, validate, and facilitate the use of an improved method for medial wall thickness quantification. We describe a novel method of wall thickness calculation based on image skeletonization and compare its results to those of common techniques. Using both theoretical and empirical approaches, we demonstrate the accuracy and superiority of the skeleton-based method for measuring wall thickness while discussing its interpretation and limitations. Finally, we present a new freely available software tool, the VMI Calculator, to facilitate wall thickness measurements using our novel method. © 2016 by John Wiley & Sons, Inc.

A new antiviral capacity for matrix metalloproteinase 12 (MMP-12) adds to our expanding understanding of matrix metalloproteinase biology, from matrix remodeling to host defense, in this issue of Nature Medicine (pages 493-502). Marchant et al. show that following viral infection, macrophages secrete MMP-12, which regulates antiviral immunity both as a transcription factor for IkBα, leading to interferon-α (IFN-α) secretion, and later by degrading extracellular IFN-α, resolving inflammation., MMPs are structurally related zinc-dependent enzymes that are produced and secreted as inactive proenzymes (except for a subset of membrane-bound forms, called MT-MMPs) that, upon activation, have the capacity to [...]