Immune cell aging in infectious diseases Flashcards
Generally speaking, what are 3 evidences that immune functions decline with age?
- Increased incidence of infections: pneumonia, influenza, tuberculosis, meningitis, urinary tract infections, COVID-19, etc.
- Increased incidence of autoimmune diseases: rheumatoid arthritis, lupus, thyroiditis, multiple sclerosis, etc.
- Weaker responses to Vaccine.
What are the different changes in innate and adaptive immune systems with age?
Innate immunity: number of cells remain the same but their activity (superoxide, apoptosis, chemotaxis, expression of TLR) decrease
Adaptive immunity: same as innate but increase in memory cells, Tregs, CD26-T-cells and cytokines
What are the two types of aging and what is their difference?
Chronological age: is the amount of time that has passed from your birth to the given date, it’s your age in terms of years, months, days, etc.
Biological age: is the functional decline of the body with the passage of time that increases the vulnerability to death
What are the two main biological age predictors?
Telomere shortening and DNA methylation are the best markers for aging detection
What are telomeres and why do eukaryotes need them?
Telomeres are DNA-protein complexes found at the ends of chromosomes
These are non coding sequences (TTAGGG)
Telomere protect and cap the chromosomes ends (specific for eukaryote cell => linear DNA, because circular DNA doesn’t need it) and has two major functions:
- avoid the loss of functional gene during DNA replication
- avoid end to end chromosomal fusion
What is a telomerase and what is its function?
Telomerase is a ribonucleoprotein complex that maintains chromosome ends, it is composed of RNA and proteins
Telomerase can repair the telomere, they are in every cell
After 80 years cells become senescent, limited (or none at all) division, and introduces genetic errors
Why telomeres get shorter in each cell of our body with cell division?
Because it is to avoid “immortal cells” or tumor cells
Only in germ cells telomeres are always long, because the telomerase gene is always up-regulated
But somatic cells have a down-regulation of telomerase gene and become senescent cells and eventually go into apoptosis
If not, they continue to proliferate and become tumor cells
Activated lymphocytes, stem cells and epithelial cells have in-between germ cells and other somatic cells telomerase regulation
What are the causes of telomere shortening?
Internal factors: - cell division - telomerase deficiency External factors: - radiations - UV light - smoking - air pollution - inflammations and infections - metabolism
Telomere length is inherited by genetics from 36-90%, it is inherited mostly from the father
Does telomere length shortens during all your life?
At an old age (60 years old) shortening doesn’t seem to happen anymore
Is telomere length connected with longevity?
People with shorter telomere have a higher mortality rate
But comparing to other species, humans have a shorter telomere length but we do live longer than them => so it is not the only thing that explains ones lifespan
Does infectious diseases accelerate immune aging?
It is shown the people with shorter telomere length in immune cells have a bigger risks of viral infections
Studies have also shown that shorter telomere length increase biological aging
Are senescent cells a problem?
Different cells having shorter telomere length creates different diseases.
Does telomere restoration reverse aging?
Restoring telomere length in mice studies reduces DNA damage and phenotypic tissue damage, but these studies need a longer followup
Do therapeutic implications work for telomere length?
Many beauty products sell telomerase activator creams and stuff, but studies show that they have not effective
