Inflammation in pulmonary arterial hypertension: is it time to quell the fire?

Inflammare, or to set ablaze, is the Latin origin of the word inflammation, a physical condition that was undoubtedly already familiar to the ancient Egyptians and Greeks. It is, however, the Roman Aulus Celsus who is credited with describing, in the first century AD, the four cardinal signs of inflammation consisting of rubor et tumor cum calore et dolore (redness and swelling with heat and pain). Two centuries later, Galen promoted the humoral view of inflammation as a potential part of the healing process rather than a pure pathological process, and may have proposed the fifth cardinal sign (functio laesa or loss of function) [1], although this is also attributed to Virchow in the 19th century [2]. And while we now know that, in many pathologies characterised by inflammation, the initial four cardinal signs can be subclinical and silent, it is clear that for Virchow inflammation was ultimately pathologic since it lead to loss of function.