The department of microbiology and immunology invited a Georgetown University professor to present his research on a new way to treat autoimmune diseases using therapeutic vaccines on Nov. 21. 

Joseph Bellanti, a professor of microbiology and immunology and director of Georgetown’s International Center for Interdisciplinary Studies of Immunology, spoke about new vaccination strategies for allergies and autoimmune diseases currently in development in his research lab. In his talk, titled “CpG and Therapeutic Vaccines,” Bellanti explained how creating vaccines with CpG nucleotides — short DNA sequences that can be recognized by immune cells — may effectively treat autoimmune conditions such as asthma. 

Bellanti said the efficacy of CpG vaccines stems from their ability to increase the activity of Treg cells, immune cells that inhibit the overactive immune systems of people with autoimmune conditions. These Treg cells can reduce inflammation, alleviate pain, swelling and other symptoms experienced by patients with autoimmune diseases.

“In diseases where there is too much inflammation, the balance is upset,” Bellanti said at the event. “There is too much inflammation and not enough neutralization and that’s what we see in autoimmune diseases such as allergies — too few Treg cells.”

According to Bellanti, previous research on the gut microbiome provided his team with insight into how increasing Treg cell activity with CpG sequences could be used as a therapeutic mechanism. His study found that methylated CpG — a chemically modified form of the DNA sequence found in certain gut bacteria — is particularly useful for CpG vaccine development.

“Microbiota with more DNA methylation have greater potential for Treg induction than those with less DNA methylation,” Bellanti said.

Dongmei Li, an assistant professor of microbiology and immunology who collaborated with Bellanti on his study, said that Bellanti’s therapeutic vaccine research differs from traditional vaccine research because therapeutic vaccines are designed to treat, rather than prevent, existing autoimmune diseases such as multiple sclerosis. 

“We introduce the notion of a ‘therapeutic’ vaccine, where the vaccine may be used as a treatment of the patient’s immediate condition, and not as a simple preventative or prophylactic measure,” Li wrote to The Hoya. “This is how we hope to manufacture direct treatments for autoimmune diseases and other allergic conditions.” 

JB Russo (CAS ’25), who attended the event, said he was surprised to learn that in the future, therapeutic vaccines may be used to treat common allergies, thanks in part to Bellanti’s research.

“The evidence was quite convincing and the wide range of potential uses for this research is amazing,” Russo wrote to The Hoya. “I am allergic to nuts and this research gives me hope for the future.”

Despite promising evidence about the mechanism of CpG vaccines, Bellanti said there are also some potential dangers associated with using a vaccine that suppresses the immune system. 

“Stimulating Treg cells can be a double-edged sword,” Bellanti said. “While this can be beneficial in re-establishing a favorable immune balance, there is the risk of inducing generalized immunosuppression, which might lead to increased susceptibility to autoimmune reactions or cancer.”

Bellanti said that one way of mitigating the risk of excessive immune suppression is, when creating a vaccine for a specific patient, to incorporate low levels of an allergen for that patient into the vaccine in order to stimulate their immune system at a healthy, moderate level. 

While Bellanti’s new study established the efficacy of CpG vaccines in vitro, his research group is currently engaged in studies of CpG vaccines in mouse models. These trials may give greater indication as to how CpG vaccines could eventually behave in human bodies when therapeutic vaccines one day become available. 

Li said despite the remaining work that needs to be done to achieve widespread CpG vaccine usage, Bellanti’s significant contributions to the field of autoimmune conditions, spanning nearly six decades, have helped bring these much-needed treatments closer to reality. 

“Autoimmune diseases have been his focus for many years, and he has been unrelenting in his efforts to lift the veil surrounding what is still one of the most frustrating areas of modern science.”