U.S. scientists have discovered the molecular secrets behind a Chinese herb\'s extract made from Chang Shan, a type of hydrangea that grows in Tibet and Nepal. Senior author Malcolm Whitman, a professor of developmental biology at Harvard School of Dental Medicine, said for roughly 2,000 years, Chinese herbalists have treated malaria using a root extract, commonly known as Chang Shan. Recent studies suggested that halofuginone, a compound derived from this extract\'s bioactive ingredient, could be used to treat many autoimmune disorders as well. \"It turns out that halofuginone triggers a stress-response pathway that blocks the development of a harmful class of immune cells, called Th17 cells, which have been implicated in many autoimmune Whitman said in a statement. \"Halofuginone prevents the autoimmune response without dampening immunity altogether. This compound could inspire novel therapeutic approaches to a variety of autoimmune disorders.\" Scientists have only recently appreciated the role of the nutrient sensing-amino acid response pathway, a pathway in immune regulation and metabolic signaling. The amino acid response pathway lets cells know when they need to preserve resources. For example, when a cell senses a limited supply of amino acids for building proteins, the amino acid response pathway will block signals that promote inflammation because inflamed tissues require lots of protein, Whitman said. The findings were published in the Nature Chemical Biology.