Buck Institute for Research on Aging
Principal Investigator: Judith Campisi
Research Team: Abhijit Kale
SENS Research Foundation Research Center
Principal Investigator: Amit Sharma/Alexandra Stolzing
Research Team: Elena Fulton
When normal cells lose their ability to replicate, they become senescent cells. Over time, senescent cells accumulate in aging tissues, spewing off a cocktail of inflammatory and growth factors, as well as enzymes that break down surrounding tissue and cause inflammation. This cocktail is the “senescence-associated secretory phenotype” or SASP. Senescent cells – and the downstream impact of the SASP – are now implicated in a remarkable litany of the diseases of aging.
On a more encouraging note, multiple studies have now documented that senolytic drugs and gene therapies that destroy senescent cells exert sweeping rejuvenating effects in aging, both in laboratory animals and animal models of multiple diseases of aging. In theory, however, senolytic therapies shouldn’t be necessary. The body’s immune system is on continuous patrol against senescent cells: our natural killer (NK) cells recognize senescent cells as abnormal, bind to them, and release substances that trigger the senescent cells to self-destruct.
An SRF-donor-funded collaboration between Dr. Judith Campisi’s lab at the Buck Institute and the SRF Research Center seeks to discover why senescent cells accumulate with age, and what might we do to enhance immune surveillance and elimination of these cellular saboteurs?
The Campisi lab has recently published three papers describing the underlying mechanism of immune evasion by resistant senescent cells (Pereira et al., 2019, Munoz et al., 2019, and Kale et al., 2020). Dr. Campisi has found that a significant proportion of senescent cells manage to evade destruction, even by fresh NK cells. These ‘resistant’ cells escape immunosurveillance and accumulate in aging tissues. Senescent cells moreover shed decoy ligands binding to NK cell receptors; another aim of this work is to screen for more such ligands shed by senescent cells.
The Buck-SRF-RC collaboration is now seeking to drill further into the mechanism of senescent cell accumulation, and test interventions. At the SRF-RC, we are currently perfecting the method of co-culturing NK and senescent cells and controlling the killing process; next, we will begin testing therapeutic interventions.
The SRF-RC scientists are also working for the first time with NK cells derived directly from aged human donors (rather than long-cultured lines of NK cells, or NK cells artificially “aged” by exposure to oxidative stress or extensive replication in culture, as has been done in the past). Using these cells will allow them to observe any direct effects of aging on NK cell senolytic activity.