Cyclic GMP-AMP displays mucosal adjuvant activity in mice

Area of Science:

• Immunology
• Vaccinology

Background:

• Mammalian cyclic GMP-AMP synthase produces cyclic GMP-AMP (cGAMP) upon activation by cytosolic double-stranded DNA.
• cGAMP stimulates STING-dependent interferon type I signaling.

Purpose of the Study:

• To evaluate the efficacy of cGAMP as a mucosal adjuvant in mice.
• To characterize the innate immune stimulation of cGAMP on dendritic cells.

Main Methods:

• Mice were immunized with ovalbumin and cGAMP.
• Adaptive immune responses (IgG, Th1/Th2 lymphocytes) were analyzed.
• In vitro studies assessed innate immune stimulation on murine and human dendritic cells.

Main Results:

• cGAMP enhanced adaptive immune responses to ovalbumin, promoting antigen-specific IgG and a balanced Th1/Th2 response.
• A notable finding was the reduced induction of interleukin-17, unlike other cyclic di-nucleotide adjuvants.
• cGAMP demonstrated innate immune stimulation activity on dendritic cells.

Conclusions:

• cGAMP shows promise as a mucosal adjuvant, enhancing adaptive immunity.
• Its unique immune response profile, including reduced Th17 activity, distinguishes it from other adjuvants.
• cGAMP is a potential candidate for developing human vaccines.