EXPERT ANALYSIS AT PDA 2014
VANCOUVER, B.C. – Nickel has long ranked at the top of common contact allergens. In fact, it earned the No. 1 spot in the North American Contact Dermatitis Group patch test results in 2009-2010.
A team of Canadian researchers began to wonder: Is it feasible to induce tolerance to nickel, or to desensitize patients to this substance found in everything from jewelry and orthodontic devices to vitamins and herbal remedies? At the annual meeting of the Pacific Dermatologic Association, Dr. Gillian C. de Gannes, a dermatologist who directs the University of British Columbia Contact Dermatitis Clinic in Vancouver, discussed preliminary findings from a proof-of-principle study designed to answer that question.
“We have a nickel detection kit for our patients – the dimethylglyoxime test – but at this point, allergen avoidance counseling is how we treat nickel allergy,” she said. “The regulatory CD4-positive CD25-positive T cells (Tregs) modulate nickel sensitivity in humans, and topical application of calcipotriol induces Treg cells to prevent both the induction and elicitation of contact hypersensitivity in mice. It’s [also] been shown that topical vitamin D analogues prevented topical sensitization to DNCB [dinitrochlorobenzene] in humans: a very potent sensitizer,” she noted ( Arch. Dermatol. 2006;142:1332-4 ).
In an effort to investigate whether topical immune modulators can stop preestablished contact hypersensitivity to nickel, Dr. de Gannes and her associates recruited 24 volunteers to participate in a double-blind, controlled trial, and randomized them to one of four groups: petrolatum ointment, betamethasone dipropionate ointment, calcipotriol ointment, and the combination of betamethasone dipropionate and calcipotriol ointments. “We first do a nickel patch test on the distal forearm to confirm that this person is sensitized to nickel,” she explained. “That’s our confirmation stage. On the opposite arm, we randomize them to one of the four groups of ointment, and we instruct them to apply a measured amount of ointment in a defined area twice daily for a week. They come back to us at the end of that week, and we repeat the nickel patch test where they applied their ointment to see whether they react or not.”
So far, preliminary results from 13 patients showed that application of some of the topical products induced tolerance and decreased reactivity to nickel, “but we’ve not yet been able to desensitize patients,” Dr. de Gannes noted. “This is just an interim analysis, and we have not unblinded the study yet. Hopefully we’ll have more meaningful results within the next year.”
The strategy is clinically relevant, she continued, because “we have hairstylists, for example, who come to us, allergic to the chemicals that they’re using. They really want to get back to their job. If this is a hand dermatitis caused by nickel or other contact allergens, and I can possibly give that hairstylist an ointment to apply to her hands in the morning and night and get back to her job, that’s a happy worker. That scenario would be a successful clinical outcome of this research, but we have a lot more work to do.”
Dr. de Gannes said that she had no relevant financial conflicts of interest to disclose.
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