LOS ANGELES A “reverse vaccine” that allows people with Type 1 diabetes to produce their own insulin has passed its first test with human subjects, according to a new study. The success points to a potential new strategy for treating those in the early stages of the disease, experts said.
The therapy is designed to protect cells in the pancreas that make insulin, a hormone the body needs to convert sugars and starches into energy. In people with Type 1 diabetes, the immune system goes haywire and attacks those crucial insulin-producing cells for reasons that medical researchers don’t understand.
Researchers dubbed the treatment a reverse vaccine because it suppresses the immune system instead of stimulating it. As hoped, the experimental vaccine reduced the number of immune system “killer” cells that went on the attack.
“We’re trying to turn off one specific immune response,” said Dr. Lawrence Steinman, an immunologist at Stanford University and senior author of the study published Wednesday in Science Translational Medicine.
About 1.25 million Americans have Type 1 diabetes. For nearly 100 years, the standard treatment has been insulin replacement therapy in which insulin is injected in amounts that correspond with blood sugar levels.
Steinman and his team designed a molecule that contained the gene for making proinsulin, the precursor to insulin. The molecule also included instructions for triggering the killer cells’ response and then shutting it down.
If everything went as planned, the DNA molecule would suppress the killer cells and allow the pancreatic cells to function properly, producing insulin.
After successful trials with diabetic mice, the team prepared to test its vaccine on humans.
Compared with patients who got the placebo, those who received the vaccine in 1.0 and 3.0 mg doses saw beneficial improvements in their levels of C-peptide during and after treatment. But three months after the treatment stopped, C-peptide levels declined, indicating the vaccine had worn off, the team wrote.
Patients in the vaccine group, no matter the dosage, saw the number of killer cells fall and the amount of proinsulin rise over 15 weeks without affecting the rest of their immune system cells.
No significant side effects or safety concerns arose during the study, the team reported.
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