Researchers identify process that prevents type 1 diabetes from progressing
Type 1 diabetes is caused by an overactive immune system. Cells that normally fight off invasion by foreign bodies like bacteria and viruses end up attacking and destroying the insulin-producing beta cells of the pancreas. Without insulin, it is impossible for a person to regulate their blood sugar levels.
However, it may be possible to prevent this. The researchers reported in the Journal of Clinical Investigation that increasing levels of the CCL22 protein appears to protect the pancreas from attacks by the immune system.
In a person with a normally functioning immune system, specialized units known as T-regulatory cells turn off the immune system's attacking cells after a foreign invasion has been defeated. However, in people with type 1 diabetes, these cells never tell the attacker T-cells to calm down.
Yet, in testing on lab mice, the researchers showed that higher levels of the CCL22 protein in the pancreas attracted more T-regulatory cells, which then prevented insulin-producing cells from being attacked.
The team was able to boost levels of CCL22 by injecting a modified virus containing pieces of DNA that encode the protein into the beta cells of mice. This caught the attention of the immune system and as CCL22 production increased, attracted more T-regulatory cells.
"It's a novel way to turn down the immune system specifically in the region of the beta cells inside the pancreas, and that may be a big advantage over general immune suppression, which can have significant side effects," said Dr. Bruce Verchere, who led the investigation.
The researchers said that they believe their findings could one day contribute to the development of a new medication that prevents type 1 diabetes from progressing. This would be most beneficial to newly diagnosed individuals who are in what is known as the "honeymoon" phase. This is when a doctor has recently diagnosed the condition but the immune system has not destroyed all of a person's beta cells, leaving them with some ability to produce their own insulin.
However, there is still a significant amount of work that must be done to develop a more complete understanding of how the CCL22 protein works before any medications can be developed, the researchers said.
"We don't know exactly how CCL22 attracts T-regulatory cells to inhibit the immune response," said Dr. Joel Montane, who also participated in the research. "Once we understand that, it may lead to a drug that can prevent or reverse diabetes."
Type 1 diabetes can be a difficult disease to live with, as it requires frequent blood sugar testing and insulin injections. Any medication that prevents the condition from worsening could be a welcome advance for the millions of people who live with it.