Inflammation is a response of the vascular tissues against diverse stimuli, such as pathogens, damaged cells or irritants. It is accompanied by symptoms like
loss of function. The older we get, the more our systemic inflammatory apparatus tends to get stuck in overdrive.
17 of immune-signaling chemicals in mouse blood raise with age. Of those 6 also increase in younger members of young/old heterochronic parabiont mouse pairs, compared with levels in mice whose circulatory systems have not been exposed to old blood [21886162; http://stanmed.stanford.edu/2011fall/article9.html].