In research at the University of Illinois at Urbana-Champaign, scientists are trying to understand how recovery might be encouraged and why people with diabetes tend to have lingering behavioral symptoms such as fatigue and apathy long after many infections end.
Their latest research found that mice given vanadium -- in its typical vanadyl sulfate form -- before exposure to a pathogen sped recovery in both diabetic and non-diabetic animals. They also tested pre-treatment with insulin-like growth factor (IGF-1), which vanadium mimics, but only the non-diabetic mice recovered quickly after exposure.
The new paper appeared on line Oct. 10 ahead of regular journal publication in the Proceedings of the National Academy of Sciences.
Researchers Daniel R. Johnson, a doctoral student, and Dr. Gregory Freund, head of the pathology department in the College of Medicine at Urbana-Champaign, don't suggest adding vanadium supplements to everyday diets. However, they said, the findings raise questions about just how it works and how it might be useful in speeding recovery.
The amount of vanadium used in the study was comparable to that found in nutritional supplements. While its nutritional value is unclear, the body needs an estimated 10 to 20 micrograms a day and obtains it mostly from plant material. Vanadium in much higher levels becomes toxic. Its use for building muscles has not been confirmed, but vanadium has improved insulin sensitivity and reduced blood sugar in diabetic people.
In their research, Johnson first administered a low dose of lipopolysaccharide (LPS), a molecule present on E. coli and other gram-negative bacteria, to both diabetic and non-diabetic mice after they had been given IGF-1. Non-diabetic mice recovered more quickly than diabetic mice, suggesting, he said, an insulin resistance state in the diabetic animals.
Next, experimental mice were pre-treated with vanadyl sulfate before exposure to LPS. Recovery after illness of the vanadium-treated mice, diabetic or not, was 50 percent faster than that of the untreated control mice.
"With vanadyl sulfate being like IGF-1, we expected to see resistance in the diabetic animals, but we didn't see that," Johnson said. "We saw similar improvement. Thus it must have been acting through a different pathway than do IGF-1 or insulin."
Johnson and Freund, also an adjunct professor of animal sciences and a researcher in the immunophysiology and behavior program at Illinois, theorize it may be vanadium's metal-related shape or its ability to inhibit tyrosine phosphatases, which help to modulate signaling proteins, in the immune system. Freund and colleagues last year documented a connection between serine phosphorylation and anti-inflammatory cytokines.
"Diabetes affects millions of people," Freund said. "It is hard to overcome many of the problems in a nutritionally dependent fashion. This research implies that metals that are trace elements may have more importance than we realize to human health, not only in preventing diseases but also in making you feel better."
It's possible, Johnson said, that taking vanadyl-sulfate-containing supplements beginning two weeks before possible exposure to gram-negative organisms might help speed recovery from subsequent infection.
Co-authors with Freund and Johnson were Jason C. O'Connor, a postdoctoral researcher in animal sciences, and Robert Dantzer, an adjunct professor in the department of animal sciences and professor at the French National Center for Scientific Research.
The National Institutes of Health, American Heart Association and U. of I. Agricultural Experiment Station funded the research.