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Protein hope in skin disorder fight

New Delhi, Feb. 27: Scientists have for the first time reversed the loss of hair colour in mice with vitiligo using a modified version of a protein, stirring hopes for a novel therapy for this intractable skin disorder.

Researchers in the US, using mice with vitiligo developed by an Indian-origin scientist, have shown that the protein can block a key immune system mechanism underlying vitiligo, a disorder marked by the loss of dark pigmentation.

Biologist Caroline Le Poole at the Loyola University, Chicago, and her colleagues have said their strategy seems to offer “a potential treatment for vitiligo”. But the scientists have cautioned that the therapy remains untested in humans and it is, therefore, still unknown whether it will lead to improved skin pigmentation in human patients.

Dermatologists estimate that vitiligo — an auto-immune disorder in which the body’s immune system’s cells destroy melanocytes, the cells responsible for the skin’s dark colour — affects one in 200 people. While doctors currently prescribe corticosteroids and other compounds and ultraviolet radiation therapy, there is no effective and reliable treatment yet.

Now, the Chicago researchers have shown that a modified version of a protein called heat shock protein 70 (hsp70) can prevent and reverse vitiligo in mice

Their findings appeared today in the journal Science Translational Medicine.

In one set of experiments, the researchers observed that the modified hsp70 could significantly blunt the immune system attack on melanocytes, preventing the loss of pigmentation in mice models of vitiligo. In another set of experiments, the modified hsp70 partially restored pigmentation.

“The protein renders the auto-immune cells dysfunctional so that they are unable to cause melanocyte destruction,” said Shikhar Mehrotra, an associate professor at the Medical University of South Carolina and a member of the research team.

Mehrotra and his colleagues had developed the genetically-engineered mice that develop vitiligo and were used by the Chicago researchers in their experiments. Mehrotra completed a PhD in Lucknow before moving to the US.

“This is a really fascinating experimental result,” said Rasheedunnisa Begum, a professor of biochemistry at the Maharaja Sayajirao University in Vadodara, Gujarat, who was not associated with the US study, but who has been studying the immune system and vitiligo. “It’s a completely new approach to tackling vitiligo,” Begum told The Telegraph .

The hsp70 belongs to a class of proteins the body makes in response to stress.

Studies by Begum and her colleagues in Vadodara have shown that patients with vitiligo appear to have high levels of certain biochemicals associated with stress as well as signs of auto-immune response. “This new work seems to connect stress with the auto-immune response underlying vitiligo,” Begum said.

The mice used in the Chicago experiments lost hair colour. “In mice, the melanocytes are in the hair — the hair loses pigmentation and the mice look like little cows, with treatment the black colour comes back,” Jose Guevera-Patino, a medical immunologist in the Chicago team told this newspaper.

The scientists caution that before the modified hsp70 can be used in humans, the protein would need to pass through rigorous safety testing. “Depending on funding for our proposed work, we may be able to start a (human) clinical trial in two or three years,” Le Poole said. A future clinical trial would require approvals from drug regulators and institutional ethics boards.