Human CD8+ EMRA T cells display a senescence-associated secretory phenotype regulated by p38 MAPK.

Cellular senescence is accompanied by a senescence-associated secretory phenotype (SASP). We show here that primary human senescent CD8+ T cells also display a SASP comprising chemokines, cytokines and extracellular matrix remodelling proteases that are unique to this subset and contribute to age-associated inflammation. We found the CD8+ CD45RA+ CD27- EMRA subset to be the most heterogeneous, with a population aligning with the naïve T cells and another with a closer association to the effector memory subset. However, despite the differing processes that give rise to these senescent CD8+ T cells once generated, they both adopt a unique secretory profile with no commonality to any other subset, aligning more closely with senescence than quiescence. Furthermore, we also show that the SASP observed in senescent CD8+ T cells is governed by p38 MAPK signalling.British Heart Foundation (LAC), a Springboard award from the Academy of Medical Science and the Wellcome trust (ECC, SMH), the William Harvey Research Foundation (SMH), a Wellcome Trust Senior Investigator Award (RWJB, SN) and The Medical Research Council (ESC and ANA) and the British Biotechnology and Biological Research Council (ANA)

Biomarkers to identify and isolate senescent cells

This paper was accepted for publication in the journal Ageing Research Reviews and the definitive published version is available at http://dx.doi.org/10.1016/j.arr.2016.05.003.Aging is the main risk factor for many degenerative diseases and declining health. Senescent cells are part of the underlying mechanism for time-dependent tissue dysfunction. These cells can negatively affect neighbouring cells through an altered secretory phenotype: the senescence-associated secretory phenotype (SASP). The SASP induces senescence in healthy cells, promotes tumour formation and progression, and contributes to other age-related diseases such as atherosclerosis, immune-senescence and neurodegeneration. Removal of senescent cells was recently demonstrated to delay age-related degeneration and extend lifespan. To better understand cell aging and to reap the benefits of senescent cell removal, it is necessary to have a reliable biomarker to identify these cells. Following an introduction to cellular senescence, we discuss several classes of biomarkers in the context of their utility in identifying and/or removing senescent cells from tissues. Although senescence can be induced by a variety of stimuli, senescent cells share some characteristics that enable their identification both in vitro and in vivo. Nevertheless, it may prove difficult to identify a single biomarker capable of distinguishing senescence in all cell types. Therefore, this will not be a comprehensive review of all senescence biomarkers but rather an outlook on technologies and markers that are most suitable to identify and isolate senescent cells