Trained immunity

Question 1

What happens with the innate immune response during second infection?

Answer 1

There is a trained response, with metabolic and epigenetic reprogramming that enhance (non-specific) effector functions.

Question 2

When will cells use glycolysis vs. oxidative phosphorylation?

Answer 2

Cells that are more inflammatory need a higher supply of energy and metabolites (glycolysis), at the risk of low efficacy. Naive (non-active) cells use more efficient energy metabolism pathways like oxidative phosphorylation.

Question 3

What happens during epigenetic reprogramming upon restimulation?

Answer 3

The chromatin is normally highly condensed in steady-state, but in resting trained immune cells it is already mildly condensed, so upon restimulation, the chromatin will be open and so there will be enhanced gene expression.

Question 4

Is trained immunity only for vaccination and infectious diseases?

Answer 4

No, excessive trained immunity can cause autoimmunity, allergy, atherosclerosis etc. Defective trained immunity can cause cancer or sepsis.

Question 5

What does the BCG vaccine do?

Answer 5

It’s a trained immunity-based vaccine that pre-activated innate cells like monocytes to engulf and kill viruses.