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Programming T cells

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If we map the epigenetic changes that occur when a T cell becomes exhausted, can we reverse them using CRISPR/Cas9? How many alterations would be required to regain function? How stable would they be?

Immunology
T cell biology
Cancer
Leonardo Ferreira
31 months ago

5 answers

2

Quite a few studies have been published to achieve this epigenetic modification with CRISPR/Cas9-derived systems. It basically uses a technique that contains 1) an single guide RNA complementary to the epigenetic sites; 2) an inactive Cas9 enzyme; 3) another enzyme fused to Cas9 for the epigenetic modification.

That's being said, most of them are in cell culture or animal disease models, and the modification was on one or very few epigenetic sites. As exhausted T cell has many epigenetic sites, new improvement may be needed. Alternatively, you can Identify the one or very few epigenetic changes that can reverse T cell exhaustion, and then try to change these one or two sites. In this sense, need to prioritize the sites from your mapping, and identify the "master" switch(es).

Epigenetic modification is intrinsically unstable, and its longevity depends on your Cas9 enzyme's half-life. You can keep the modification on long if you use long-lasting Cas9 system, such as lentiviral delivery system.

Hope this help.

Jun Tang
31 months ago
I agree that epigenetic modifications using dead Cas9 or similar are potentially unstable, but enhancers active specifically in exhausted T cells have been identified. Why not just permanently delete these enhancers from the genome of T cells using CRISPR/Cas9? - Leonardo 30 months ago
Well said - Dr. David E. 19 months ago
1

What is the evidence that exhaustion is due to epigenetic changes? I assume it is analogous to a muscle after depletion of glycogen - a metabolic change that is reversed by rest and an energy source. Other immune cells, neurons, etc. all participate in functions requiring stores of substances that are used and regenerated. Then in an even shorter time frame, is membrane polarization/depolarization which is ion channel shift (and energy, in the form of ATP, dependent). Nature has devised many mechanisms for biological responses and though ultimately somehow written in the DNA, also responsive to very immediate environmental cues. Think T-cell and DC exhaustion is due to cytokine depletion and probably membrane alteration, e.g. Receptor recycling.

Meg B
31 months ago
Enhancers active specific in exhausted T cells have been identified using epigenetic analyzes, such as chromatin modification mapping) - Leonardo 30 months ago
Interesting - Dr. David E. 19 months ago
0

If you couch gene expression as an epigenetic event, I suppose you could approach it this way. What is the lifespan of a T-cell? Does ex vivo or in situ manipulation make sense?

Meg B
31 months ago
T cells can be kept in culture for weeks. Ex vivo genetic manipulation using viral transduction or electroporation is common. There is nevertheless a recent report of T cell modification in situ using nanoparticles , and more studies should ensue in the near future. - Leonardo 30 months ago
Thanks - Dr. David E. 19 months ago
0

Recent studies suggest that memory T-cell differentiation continues for weeks or months following antigen clearance, although commitment to the memory lineage occurs during the effector stage of development. Several variables associated with priming, such as the duration of antigenic stimulation, degree of co-stimulation, cytokine environment, and CD4(+) T-cell help, may program epigenetic qualitative differences into the ensuing effector and memory populations. Defining what memory qualities best protect the organism from re-infection, as well as how commitment to the memory lineage is specified following T-cell activation remains an important goal.

David Barckhoff-Sag-Aftra/Producer, Director
31 months ago
Does that mean you think that different models might yield different types of T cell exhaustion? - Leonardo 30 months ago
0

Enhancers active specifically in exhausted T cells have been identified. Why not just permanently delete these enhancers from the genome of T cells using CRISPR/Cas9?

Leonardo Ferreira
30 months ago

Have some input?