Animal models for Celiac Flashcards
How this disease is chronic?
Gluten is composed of glutenins and gliadins, and they can pass the epithelial layer. They get deaminated by tissue transglutaminase. And Abs are created against transglutaminase. Transglutaminase is just a repair enzyme, if there’s a damage in the intestine it’s activated. Somehow this enzyme is active in these patients and it binds to gliadins and deaminates them.
Only deaminated gliadins fit in HLA DQ2/8. It introduces negative charges and it allows it to stick.
There’s memory T cells that recognise HLA-DQ2/8= you get memory.
So some people have the predisposition, but no Celiac disease, so there is going to be some inflammation on intestine no matter what, but most of them never get it.
Studying tolerance in intestine - mice Ova model
The thing is, all the things we ingest aren’t really ignored, they are always sampled/analyzed by immune system.
Study: You give constantly Ovalbumin to a mouse that never eaten Ova before: it becomes tolerant in time. So if you inject Ova to a mice, even with an adjuvant, it shouldn’t respond.
Ova is sampled in small intestine by APCs and presented to naïve T cells in peripheral LN. = It induces Treg. = Foxp3, suppressive. If you administer this now, with an adjuvant that causes strong inflammation though = you won’t get a Treg response. No danger signal = tolerance.
After you induce a mouse with Ova and get Tregs, you put it in a new mouse that has never seen Ova before and try to immunize the new mouse. If you don’t get any Tregs = you can immunize the mice. Cells obtained from Peyer’s patch or LN = can suppress the reaction.
So if you have a healthy intestine, and you get a harmless soluble protein and it doesn’t cause any danger signals = get Tregs/tolerance. Once you have it, you keep it = memory.
In this stage, Tregs overcome actively CTLs. = But if you want to break it, you can immunize again with very strong adjuvants.
Mice don’t develop Celiac’s = so they aren’t useful as a model. Why don’t they develop Celiac, what makes them resistant? - Mice studies
2nd mice has HLA-DQ + deamidated gliadin specific T cells. = give the mice deaminated gliadin. What you expect? Celiac’s. A lot of division of T cells are observed. Dividing T cells make a lot of IFN gamma and IL-6 = very inflammatory cytokines. But there’s no intestinal damage! So disease is induced, but there must be regulation.
So even though you give mice everything to develop a disease = they didn’t, expected.
the number of Tregs doesn’t change between controls and inflammation induced mice: but there’s huge IL-10 response! There’s still IFN gamma induced with immunization, but IL-10 is so much that it can compensate it. There’s cells that produce both IL-10 and IFN-gamma, more cells produce IL-10 only, and less cells that only produce IFN-gamma.
So IL-10 must be the master regulator that prevents the inflammation from happening
Another study: Immunize the cells for gliadin + give gliadin specific Tregs - repressive = and the immunity decreased. In T cell responses, very strong IL-10 secretion is observed.
: Block IL-10 receptor, much more IFN gamma is secreted. = Suppression of Tregs weakened
If we feed mice gliadin in a very artificial way = we get IL-10. Does this happen in vivo? - mice model - answer to mice model IL-10 discussion
APCs cannot take IL-10 signal. IL-10R blocked.
Cre/lox system: Only APC IL10R CKO induced.
You only see more infiltration + crypt hyperplasia in older mice!
IEL increase, B/T cells increase.
If mice lack IL-10R, with time it gets immunogenic for gluten. = like Celiac’s.
Much more CD4/CTL in IL10R CKO, but not much increase in Tregs.
In duedonum, where the most inflammation is seen in Celiac’s, IL10R show the highest IFN-gamma / IL17a, IL21 levels.
IL10 really primes APCs to be suppressive = otherwise you get inflammation.
So you can break the tolerance of mice. Block IL-10, you get disease.
Put them on gluten free diet: Hyperplasia fixed. So the effect that we see depends on gluten. Lymphocytes decreased on a gluten free diet in IL-10 CKO mice.
Inflammation is also reduced.
They became like Celiac model now.
Maybe there’s IL-10 defiiciency in humans.
When you miss IL-10 you get very severe IBD = so Celiac’s disease isn’t due to complete failure of IL-10, maybe a bit of less causes Celiac’s.
