Thursday, January 13, 2011

Dogs: eczema patients' best friend in more than one way

And now for something completely different...

Dog eczema!

Quite frequently I see items in my news feed about canine eczema. I haven't paid them any attention. But today I saw something worth commenting on. Imulan, a company based in Arizona, announced that it had developed a biomarker for canine eczema.

Who cares? was my first thought. But I was intrigued, because in reading the NIAMS roundtable summary the other day, I'd seen that dogs are considered a potential experimental model for human eczema. So any research done using dogs as models might not only benefit dogs, but also humans.

I wondered why it was worth anyone's time to develop a biomarker for eczema in dogs. (A biomarker is any protein or metabolite in your body whose level is correlated with your risk of developing a disease-- or the chance that you have it already. Biomarkers are emerging as a biomedical field--for example, Tethys Bioscience in Emeryville, CA is developing biomarkers for diabetes.) If you have eczema, it shows. Why do you need a biomarker?

Then I understood. Dogs scratch all the time. They get fleas, etc. They roll in their own feces and other stuff. So it's harder for a veterinarian to diagnose eczema for a dog than for a human doctor to diagnose it for a patient. A biomarker would enable the vet to make a quick, definitive diagnosis.

Imulan says that its canine eczema biomarker is based on its "T cell receptor therapeutic peptide vaccine." This opened my eyes. They're claiming to have a vaccine for eczema! Bold. I have no idea what data this is based on. Nor do I know exactly what a "TCR peptide vaccine" is.

I did a Google search and it seems that there have been a number of papers published on TCR peptide vaccines, although the ones I checked out concerned vaccines against lymphocytic cancer in mice. And those were EXTREMELY preliminary.

The idea, Imulan says, is that a messed-up T cell balance (type 1 helper vs. type 2) is at the root of eczema (this, of course, is not established in humans; the imbalance is likely a symptom, not the original cause) and so you need to cancel out, or mute, the type 2 T cells. In short, as I understand it, you vaccinate so that your body produces a lot of antibodies against YOUR OWN T cells, thus shutting them down.

This seems nutty to me, and if tried in humans, likely to lead to something like the "cytokine storm" that nearly killed the six volunteers in a 2006 trial of an experimental T cell-stimulating antibody. But Imulan claims their vaccines have shown promise in dogs.

I'll have to ferret out their data (pun intended).

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