“…This article is an introduction to a new topic within the ‘ ARD collection’ series. In the ‘Greetings’ 1 year ago,24 the plan to provide ARD ’s readership with such virtual issues—a compilation of ARD- papers on a specific subject whose publication had been scattered over a period of several years—was introduced. These virtual issues allow readers who do not have a main focus on that particular research or therapeutic area to appreciate, in a concise way, some of the advances made in that field.…”