Autoimmune Diseases May Succumb to New Drug Strategy

New pharmaceuticals to fight autoimmune diseases, such as multiple sclerosis, rheumatoid arthritis and psoriasis, may be identified more effectively by adding genome analysis to standard drug screening, according to a new study by a research team led by UC San Francisco and Harvard researchers, in collaboration with Tempero and GlaxoSmithKlein.

In a study reported online April 17, 2014 in the journal Immunity, the scientists combined drug screening with state-of-the-art techniques for analyzing the genome, leading to three small molecules that improved symptoms in a mouse form of multiple sclerosis.

The three potential drug candidates, selected from a large library of screened chemicals, each knocked down the response of Th17 cells, a type of immune cell that drives many autoimmune diseases by attacking normal cells in the body. More specifically, the drugs homed in on an essential molecule within the Th17 cells.

“We examined what makes Th17 cells – which play a crucial role in multiple autoimmune diseases – distinct from other closely related T cells within the immune system,” said Alexander Marson, MD, PhD, a leading T cell expert and member of the UCSF Diabetes Center. “Then we investigated several small molecules that inhibit the development and function of these cells. When the Th17 cells were hit by these molecules we saw less severe multiple-sclerosis-like symptoms in the mice.”

The research team, led by Marson and Vijay K. Kuchroo, PhD, an immunologist at Brigham and Women’s Hospital in Boston and Harvard Medical School, combined powerful techniques to shed light on a class of protein molecules within cells known as transcription factors.

Drug designers have rarely targeted transcription factors. Each transcription factor binds to DNA at a unique set of locations along the 23 pairs of chromosomes, and thereby influences which genes are turned on and off to trigger the protein production that drives cell development and function.

Different transcription factors shape the development of different types of T cells within the immune system, Marson and others are discovering. In their new study, Marson found that the transcription factor called ROR gamma t has a unique role in guiding development of Th17 cells, while inhibiting the development of other immune cells.

Preventing Th17 cells from developing by inhibiting the function of ROR gamma t appears to be an effective strategy for fighting autoimmune diseases, Marson said.

“There already are drugs in clinical trials for autoimmune diseases – including psoriasis and rheumatoid arthritis – that are antibodies for IL-17 or IL-17 receptors,” Marson said, referring to signaling molecules secreted by Th17 cells that can help trigger an attack our own healthy tissue, and the receptors that receive those signals. “This is an entirely different and promising approach to fight autoimmune disease,” he said.

“Our studies map a path to targeting transcription factors and provide both insight into how transcriptional regulators shape the identity and affect the development of Th17 cells, and also into how different drug molecules might affect these regulatory circuits in the cells,” he said.

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