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Chronic idiopathic pruritis

People who suffer itching with no clear cause may have defects in their immune systems that haven’t been recognized. In a small study of patients who struggle with itching but have no known cause, researchers from the Center for the Study of Itch at Washington University School of Medicine in St. Louis identified several immune system irregularities that may underlie the urge to scratch. The patients suffer from what doctors call chronic idiopathic pruritis. Studying blood samples and skin biopsies, the researchers have found some very unusual things in the immune systems of these patients.

SOME PEOPLE SUFFER HAVE BAD PROBLEMS WITH ITCHING BECAUSE THEY HAVE A RASH OR SOME OTHER SKIN CONDITION. BUT OTHERS HAVE ITCHING PROBLEMS WITH NO KNOWN CAUSE. NOW RESEARCHERS FROM THE CENTER FOR THE STUDY OF ITCH AT WASHINGTON UNIVERSITY SCHOOL OF MEDICINE IN ST. LOUIS HAVE IDENTIFIED DEFECTS IN THE IMMUNE SYSTEMS OF SOME PATIENTS WITH THAT TYPE OF ITCHING THAT MAY UNDERLIE THE URGE TO SCRATCH. JIM DRYDEN HAS MORE…

ALTHOUGH IT’S RELATIVELY UNCOMMON, A CONDITION CALLED CHRONIC IDIOPATHIC PRURITIS IS ONE OF THE MOST DIFFICULT TYPES OF ITCHING TO TREAT BECAUSE THE BEST TARGET FOR THERAPY REMAINS UNKNOWN. WHEN A PERSON WITH AN ITCHY RASH GOES TO THE DERMATOLOGIST, THE DOCTOR OFTEN ORDERS A SKIN BIOPSY TO SEE WHAT’S UP. BUT IN PATIENTS WITH ITCHING WITHOUT A KNOWN CAUSE, THERE’S NOTHING TO BIOPSY. WASHINGTON UNIVERSITY DERMATOLOGIST BRAIN KIM SAYS SOMETIMES PEOPLE WONDER IF THE ITCHING IS “ALL IN THEIR HEADS.”

(act) :14 o/c our mission

It is often viewed as a “wastebasket term” in that there’s

nothing really wrong with these patients. But, you know, if it

was simply, you know, a psychiatric disorder or something not

otherwise specified, we should try to figure out what’s going on.

And that’s, really, what we’ve taken as our mission.

KIM RUNS A CLINIC FOR PEOPLE WITH CHRONIC ITCHING. AMY XU, A MEDICAL STUDENT WHO WORKS IN KIM’S LAB, SAYS SOME OF THE PATIENTS HAVE ECZEMA OR SOME OTHER KNOWN SKIN CONDITION, BUT OTHERS DON’T.

(act) :16 o/c their itch

So these patients have itch that is of unknown origin,

meaning that we do a whole bunch of lab tests, and we get

a chest X-ray and other things on them and find that they

really don’t have any primary, like, skin conditions, or

other medical conditions, that could be causing their itch.

XU IS THE FIRST AUTHOR ON A NEW STUDY FROM KIM’S LAB THAT ANALYZED SKIN AND BLOOD SAMPLES FROM PATIENTS WITH ITCHING, BUT NO KNOWN CAUSE, TO SEE WHETHER THEY COULD FIND ANY SIMILARITIES BETWEEN THE PATIENTS. KIM SAYS THEY DID FIND ELEVATED LEVELS OF IMMUNE CELLS, CALLED EOSINOPHILS, IN THOSE SAMPLES. EOSINOPHILS USUALLY ARE MARKERS OF ALLERGIC INFLAMMATION.

(act) :13 o/c the itch

The thought is, could that just be secondary to scratching?

It’s possible, but then you look deeper in the blood, and then

you see profound immune defects in the blood. There is this

immune dysregulation, and it’s very likely that this immune

dysregulation is contributing to the chronicity of the itch.

THE STUDY LOOKED ONLY AT A SMALL SAMPLE A PATIENTS. THERE WERE 4 IN THIS INITIAL STUDY. BUT KIM FOUND THAT CERTAIN IMMUNE SYSTEM DEFECTS WERE COMMON IN 3 OF THEM.

(act) :21 o/c a rash

Three of them have elevated IgE, which is a marker of allergic

inflammation. Three of them have elevated eosinophils, which is

another marker of allergic inflammation. What’s unique about them

is that they don’t have a history of atopic dermatitis or other

allergic disorders, and the other thing that’s common to all of them

is they typically don’t have a rash.

KIM SAYS THE EARLY FINDINGS SUGGEST THAT WHEN IT COMES TO THIS SORT OF UNEXPLAINED CHRONIC ITCHING, IT ISN’T REALLY ALL IN THEIR HEADS.

(act) :21 o/c for instance

We’ve now been more routinely doing these clinical tests to

identify what’s going on in these patients, and, in fact, we

have many more patients; and what we’re finding out is that the

immune dysfunction is now stratifying across different defects.

Some patients will have such profound defects that we’ve actually

sent them to our colleagues in allergy and immunology, for instance.

KIM’S LAB IS NOW WORKING TO MAKE MOUSE MODELS THAT HAVE SOME OF THE SAME UNDERLYING IMMUNE DEFECTS IN ORDER TO DEVELOP BETTER TREATMENTS. HIS TEAM REPORTS ON THOSE DEFECTS IN THE JOURNAL OF THE AMERICAN ACADEMY OF DERMATOLOGY. I’M JIM DRYDEN…

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