Harnessing immunotherapy to reverse Type 1 diabetes

In patients with Type 1 diabetes, T cells in the immune system mistakenly attack islet cells in the pancreas that make insulin. Scientists at Boston Children’s Hospital have come up with a way to thwart this wayward autoimmune reaction, and it involves a protein that plays a prominent role in new immunotherapy treatments for cancer: PD-L1.

PD-L1 is called an immune "checkpoint" because it prevents T cells from recognizing and attacking cancer. Drugs that inhibit PD-L1, like Genentech’s Tecentriq, have proven effective for fighting some cancers. But the Boston Children’s researchers believe that in diabetes, PD-L1 may actually need to be boosted. That’s because the protein appears to be instrumental in crippling the "autoreactive" T cells that destroy insulin-producing cells.

The researchers tested their theory by pre-treating blood stem cells so they would produce excess PD-L1 and then infusing them into mouse models of diabetes. The treated stem cells sped towards the pancreas, curing almost all of the mice of diabetes in the short term, according to a press release. About 30% of the animals remained diabetes-free for the duration of their lives. The research was published in the journal Science Translational Medicine.