Cellular Senescence: Difference between revisions

* '''Senescence-Associated Secretory Phenotype (SASP)''': One of the defining features of senescent cells is their altered secretory profile. They release a mix of pro-inflammatory cytokines, chemokines, growth factors, and proteases. While the SASP can have beneficial roles, such as in wound healing and tissue regeneration, its chronic presence is associated with a pro-inflammatory environment, which is implicated in various age-related pathologies.

Several factors can induce cellular senescence, underscoring the multifactorial nature of this biological phenomenon:

* Additionally, other lesser-known factors like epigenetic changes, mitochondrial dysfunction, and chronic inflammation have also been implicated in driving cells toward senescence. As research advances, our understanding of these causative factors and their interplay will pave the way for more effective therapeutic interventions targeting cellular senescence.

Senescent cells are cleared from the body primarily through the immune system, specifically by specialized immune cells that recognize and eliminate these non-dividing, functionally altered cells. Here's a detailed look at the mechanisms:

In healthy young organisms, the immune system efficiently clears senescent cells, ensuring they don't accumulate in tissues. However, as organisms age and the immune system's function declines (a phenomenon known as immunosenescence), the removal of senescent cells becomes less efficient. This reduced clearance, combined with an increased rate of cells entering senescence, can result in the accumulation of senescent cells in tissues, contributing to aging and age-related diseases.

In humans, cellular senescence is a complex process and can be induced by various stimuli or stresses. While the term "senescent cells" often refers to cells that have undergone the senescence program in response to these stresses, it's worth noting that there isn't just one type of senescent cell. Instead, there are multiple subtypes or classifications based on the cause of senescence. Here are some of the main types of senescent cells based on the inducers of senescence:

The senescent state is typically characterized by a halt in cell division, resistance to apoptosis (cell death), and often the secretion of a mix of bioactive molecules known as the senescence-associated secretory phenotype (SASP). The SASP can have both beneficial and detrimental effects, depending on the context.

Senescent cells exhibit a unique pattern of accumulation in the human body, marked by an exponential rise during mid-life followed by a decline in advanced age. Understanding this pattern offers insights into aging processes and potential interventions.