How getting older affects the immune system: Immunosenescence and “Inflammaging”

What is imunosenescence?

Immunosenescence is defined as the changes in the immune system associated with age.

The most important features of immunosenescence are:

- accumulation in “immunological space” of memory and effector cells
- this is caused by stimulation by repeated infections and exposure to antigens (inhalant allergens, food, etc.)

The state of chronic inflammation that characterizes senescence has an impact on survival and fragility.



Autoimmune conditions vs Immunodeficiency (click to enlarge the image).

What causes immunosenescence?

Immunosenescence is characterized by “remodelling” of the immune system, induced by oxidative stress (apoptosis plays a role in this):

- remodelling of apoptosis
- inflammaging
- up-regulation of immune response, secretion of pro-inflammatory lymphokines

What is inflammaging?

Aging is characterized by a chronic, low-grade inflammation, and this phenomenon has been termed as “inflammaging.” Inflammaging is a highly significant risk factor for both morbidity and mortality in the elderly people, as most if not all age-related diseases share an inflammatory pathogenesis.

Inflammaging is macrophage centered, involves several tissues and organs, including the gut microbiota, and is characterized by a complex balance between pro- and anti-inflammatory responses.

What causes “inflammaging”?

A possible cause of inflammaging is the continuous stimulation of macrophages by molecular garbage whose generation–disposal balance becomes impaired with age (‘Garb-aging’).

“Inflammaging” is also characterized by a decrease in “naive” T cells:

- reduction of CD8 virgins, CD4+ T cells and CD19+ B cells
- exhaustion of T cell-virgin (CD95−), which are replaced with the clonal expansion of CD28-T cells

How does inflammaging kill?

Increase of pro-inflammatory cytokines is associated with dementia, Parkinson’s disease, atherosclerosis, diabetes type 2, sarcopenia and a higher risk of morbidity and mortality.

Can we fix it?

A modulation of immune responses and apoptotic phenomena could be useful to reduce age-related degenerative diseases, as well as inflammatory and neoplastic diseases.

References:

Immunosenescence in aging: between immune cells depletion and cytokines up-regulation http://bit.ly/2DwcVC6
Chronic Inflammation (Inflammaging) and Its Potential Contribution to Age-Associated Diseases | The Journals of Gerontology: Series A | Oxford Academic http://bit.ly/2DxzypH
Inflammaging and ‘Garb-aging’ http://bit.ly/2Clpxwl

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