New Use For Old Drug -- Arthritis, Cancer And More, VARI Says
New research from the Grand Rapids-based Van Andel Research Institute demonstrates on the molecular level how the anti-malaria drug chloroquine represses inflammation, which may provide a blueprint for new strategies for treating auto-immune diseases from arthritis to multiple sclerosis to some cancers.
The study was published in the scholarly journal Science Signaling.
"The implications of this study are significant," said Henry F. McFarland, former chief of the neuroimmunology branch of the National Institute of Neurological Disorders and Stroke. "These results provide a mechanistic basis for therapeutic strategies for treating inflammation and autoimmune diseases and should provide exciting new approaches which can be tested in clinical trials."
The National Institutes of Health lists more than 80 common autoimmune diseases including asthma, Guillain-Barre syndrome, multiple sclerosis, myasthenia gravis, psoriasis, rheumatoid arthritis, and some types of cancers among many others.
H. Eric Xu, Head of the VARI Center for Structural Biology and Drug Discovery, and his colleagues showed that chloroquine represses inflammation through synergistic activation of glucocorticoid signaling. Glucocorticoids are a class of steroid hormones that bind to the glucocorticoid receptor present in almost every vertebrate animal cell. They are among the most potent and effective agents for treating inflammation and autoimmune diseases.
Synthetic glucocorticoids are used for treating asthma, allergies, and rheumatoid arthritis. Since glucocorticoids also interfere with some of the abnormal mechanisms in cancer cells, they are also used in high doses to treat certain cancers such as leukemia and lymphoma. However, at therapeutic dosages, glucocorticoids can cause a range of debilitating side effects including diabetes, osteoporosis, skin atrophy, and growth retardation.
"The discovery and development of novel uses of glucocorticoids that retain their beneficial therapeutic effects but reduce undesired adverse side effects remains a major medical challenge," said VARI Research Scientist Yuanzheng He, lead author of the study.
The VARI research revealed an unexpected regulation of glucocorticoid signaling by lysosomal functioning. Lysosomes are organelles found in animal cells that use enzymes to break down waste materials and cellular debris.
Researchers found that they could mimic the effect of chloroquine by inhibiting lysosomes in the cell. They believe that the development of new therapies for treating inflammation and autoimmune disease will involve strategies that combine both glucocorticoid and lysosomal inhibitors.
"We have known for some time that both steroids and lysosomes affect the immune system, but we didn't know that they worked together," said VARI President and Research Director Jeffrey Trent, Ph.D. "Researchers now have a clear path forward for undertaking projects to develop glucocorticoid and lysosomal inhibitors, and to improve the efficacy and potency of chloroquine as a therapeutic agent."
More at www.vai.org.
