Chitosan could boost body’s immune response to vaccines

May 13, 2016

A substance gleaned from the shells of crustaceans may hold the key to harnessing the power of the immune system to create new vaccines against diseases.

As researchers work to find new ways to harness the body’s immune response to fight diseases like cancer, a new report reveals that certain adjuvants may be the key.

Adjuvants enhance the body’s immune response to vaccination and have long been a component of vaccines, but researchers are now gaining fresh insight into how they work.

A new report, “The Vaccine Adjuvant Chitosan Promotes Cellular Immunity via DNA Sensor cGAS-STING-Dependent Induction of Type I Interferons” published in Immunity, reveals the mechanism by which the adjuvant chitosan induces immune response. Researchers say it could provide key information for developing vaccines that trigger cell-mediated immunity.

Chitosan is a polysaccharide derived from the chitin found in the exoskeleton of crustaceans. It has many uses in a variety of industries, and it already utilized in medicine for bandages, hemostatic devices, transdermal drug delivery and more.

What it may also be able to do is trigger stronger cellular immune responses.

Ed C. Lavelle, PhD, FTCD, immunology professor at Trinity College Dublin’s School of Biochemistry & Immunology and the lead researcher on the project, says chitosan can activate dendritic cells and promote adapted or acquired immune responses through a DNA-sensing pathway in cells-a pathway that normally only senses pathogens. Chitosan can promote dendritic cell maturation by inducing type I interferons and enhance antigen-specific T helper 1 responses and engage the STING-cGAS pathway, which triggers the expression of inflammatory genes.

 

Lavelle says there are not enough vaccines for conditions-including infectious diseases like tuberculosis and malaria, but also certain bacterial and virus diseases-in which cellular immunity is required to mediate protective immunity. There is also a desire to develop vaccines against certain cancers, with the intent of inducing cellular immune responses to attack tumor cells. Chitosan may be able to help mount this immune response.

“While traditional vaccine adjuvant strategies have been very effective in driving neutralizing antibodies that can protect against for example tetanus, polio and hepatitis B, these adjuvants have been less effective in triggering cellular immune responses,” Lavelle tells Medical Economics. “Our finding that it is possible to target a DNA sensing pathway in cells with a polysaccharide indicates that novel adjuvants can be designed to selectively activate this pathway as a means to induce stronger cellular immune responses.”

A number of cationic adjuvants designed to enhance cellular immunity are currently in clinical trials, and Lavelle says he hopes chitosan can also be incorporated into vaccines in the future.

“We are currently investigating whether the effectiveness of these adjuvants which are currently undergoing clinical evaluation, like chitosan require the DNA sensing cGAS-STING pathway to trigger cellular immunity,” Lavelle says.