Zinc is a mineral that's known to boost the function of the immune system, and now scientists have learned more about how it works. Zinc seems to help cells in the immune system, T cells, fully mature into pathogen fighting cells that are on the front lines of the immune system. The mineral seems to boost regeneration in an organ called the thymus, which generates those T cells. Researchers have also now identified an experimental molecule that mimics the action of zinc in the thymus, but is even better at promoting thymus regeneration. The findings have been reported in the journal Blood.
The scientists found that in a mouse model fed a zinc-free diet, the thymus shrank, just as it does when humans lack dietary zinc. When deprived of zinc for only three weeks, the mice also generated fewer mature T cells. T cells were found to need zinc for maturation. A lack of zinc impairs recovery in the thymus after the immune system is destroyed or eliminated in mice, a situation that might occur in humans about to receive a blood stem cell transplant. But supplemental zinc was found to aid thymus and T cell recovery.
It seems that regeneration in the thymus is influenced by the levels of zinc in the area surrounding cells. Cells can sense zinc levels through a molecule called GPR39. While T cells are developing, their zinc levels increase, but if they are damaged, T cells release it. An experimental compound was found to stimulate GPR39 by mimicking a rise in zinc levels, promoting renewal in the thymus.
"This study adds to our knowledge of what zinc is actually doing in the immune system and suggests a new therapeutic strategy for improving recovery of the immune system," said senior study author Dr. Jarrod Dudakov, an immunologist at Fred Hutchinson Cancer Research Center.
"What we think is going on is, as you give zinc supplementation, that gets accumulated within the developing T cells. It gets stored and stored and stored, then the damage comes along and the zinc is released," Dudakov explained. "Now you have more zinc than you normally would, and it can instigate this regenerative pathway." He added that the experimental compound targets GPR39 directly, so it can cause same outcome without requiring pretreatment.
While more research will be needed before this work can be brought to the clinic, the researchers are now investigating how zinc is involved in immune system repair, and might eventually be used to improve therapeutics. Such treatments might be helpful to people with immune systems that are in decline because of aging or cancer, noted Dudakov. His research team is also investigating compounds that stimulate GPR39.
Since transplant patients already take minerals, zinc levels should be tested prior to starting a zinc regimen, noted the researchers. Right now, there is not a good way to assess zinc levels, and the researchers are working to develop one.