Exercise and the immune system 3 Flashcards
What are some non-infectious reasons that someone may have URTI symptoms?
Asthma, airway epithelial trauma due to increased ventilation or exposure to cold air, allergy
What are some viral related causes that might not be to do with catching the virus while exercising?
It is possible that viruses can be reactivated in someone’s body–> epstein barr virus, herpes
What did Pedersen et al show regarding the effect of exercise on tumors?
Exercise can lead to tumor suppression in rodents
What were the conditions of the running wheel experiment done by Pedersen et al?
Two groups of mice, one had access to a running wheel, one didn’t. Both were administered tumor cells
Tumor size results of running wheel experiment done by Pedersen?
Group without access to a wheel had larger tumors (statistically significant) than the group that did have a wheel
Immune cell results of wheel experiment done by Pedersen et al?
More CD3, CD8, CD4 and NK cells in group that had wheel access
How was the effect of stress controlled for in the wheel study?
Propranolol was administered
Effect of propanolol?
Beta blocker so blocked the effect of stress hormones
What happened to the tumor size of the exercised mice once the effect of adrenaline was blocked?
It increased to the same size as non-exercised animals
How does physical activity reduce risk of cancer?
Every time someone exercises immune cells are mobilised into the blood where they can go to tissues where they are needed, such as tumors
How can in vivo immune responses be assessed in humans?
Via vaccination
Conditions of Eskola study in 1978?
4 athletes ran a marathon distance and were immediately given tetanus vaccine. Blood was taken 15 days later to assess immune response
Results of Eskolas marathon study?
Showed that running for 2.5 hrs doesnt suppress antibody responses, might actually enhance responses
Groups in Kate Edwards study?
Exercise group exercised their upper arm eccentrically (to increase heart rate and damage and inflame tissues where the muscle would be administered) and control group who did nothing. Half of each group receive the full dose while the other half received a half dose (creating 4 groups)
Why were half doses of the vaccine given to participants in Edwards study?
To mimic what happens in older age–> older people don’t respond as well to vaccination
Effects of exercise on full dose vaccine?
No benefits of exercise were observed for the full dose vaccine
Effects of exercise on half dose vaccine?
Generally the exercise group responds better than the control group to the vaccine
Why may exercise improve half dose vaccine response?
Increase in heart rate and thus blood flow to tissues
Why would an increase in blood flow to tissues improve vaccine response?
better identification of antigens in vaccine, and increase in immune cell release into blood which would go to inflammation sites (i.e. where the vaccine is administered)
How can inflammation increase vaccine response?
Inflammation attracts immune cells via the secretion of cytokines
Which group could benefit from exercising before vaccination?
Older individuals
What was the effect of a single bout of exercise in antibody responses in older adults?
No significant effect
What is aging of the immune system known as?
Immunosenescence
Where do T cells mature?
The thymus
What are three components of the thymus?
Cortex, medulla, fat
In which parts of the thymus do early T cells mature?
Cortex and medulla
What happens to the size of the cortex and medulla of the thymus as you age from 18 ish?
They reduce
What happens to the amount of fat in your thymus as you age?
It increases relatively and absolutely
Where do stem cell progenitors arise from?
Bone marrow
In what form do t cells enter the thymus?
Thymocytes or T cell precursors
In what form do t cells leave the thymus?
Naive t cells
Involution definition?
Shrinkage
What happens to the amount of naive t cells as you age?
Decreases
What happens to the amount of different memory t cells as you age?
Decreases (limited antigenic targets as you age)
Which homing markers do naive t cells express?
CD62L, CCR7
Which homing markers do senescent t cells not express?
CD62L, CCR7
What are senescent t cells?
Older t cells
Which differentiation markers do senescent t cells express?
CD57, KLRG1
Which differentiation markers do naive t cells express?
CD27, CD28
What was observed about the level of maintenance of naive CD8 t cells when aging in different fitness levels?
If VO2 max was higher, the maintenance of naive CD8 t cells in aging was better
What generally happens to the amount of effector CD8 t cells as you age?
It increases
What was seen regarding exercise effect on CD4 t cell count in older age?
More active people had more CD4 t cells when they are older
Effect of exercise on amount of senescent t cells as you age?
More exercise generally leads to less of an accumulation of senescent t cells
What effect did lifelong exercise have on the levels of IL6?
More exercise was correlated with lower levels of IL6
What can IL7 do regarding muscle hypertrophy?
Promote it
Effect of IL7 on immune cells?
naive t cells (CD4 and CD8) increase
Effect of resistance exercise on IL7?
Increases it
One possible mechanism behind exercise effect on senescent t cells?
Naive and senescent t cells in blood at rest, they are mobilized into the blood in response to exercise. Hours post exercise, the senescent cells are sent to the bone marrow where they receive pro apoptosis signals. This death creates space for new naive t cells to be produced
