A dilemma for mucosal vaccination: efficacy versus toxicity using enterotoxin-based adjuvants

Area of Science:

• Immunology
• Vaccinology
• Neuroscience

Background:

• Cholera toxin (CT) is an effective adjuvant for mucosal vaccines, inducing Th2-dependent immune responses.
• Concerns exist regarding CT's inherent toxicity, limiting its use in human vaccines.
• Nasal administration of antigen and CT is explored for mucosal IgA responses.

Purpose of the Study:

• To investigate the potential central nervous system (CNS) toxicity of cholera toxin (CT) when administered nasally.
• To evaluate the mucosal adjuvanticity and immune effects of CT in aged mice.
• To discuss challenges in developing effective mucosal vaccines due to CT's toxicity.

Main Methods:

• Nasal administration of CT and CT-B in mice.
• Examination of CT and CT-B accumulation in olfactory pathways and CNS.
• Assessment of mucosal immune responses and immune dysregulation in aged mice.

Main Results:

• CT and CT-B were found to accumulate in the olfactory nerves, epithelium, and olfactory bulbs after nasal administration in mice.
• Early immune dysregulation was observed in the mucosal immune system of aged mice receiving CT.
• Limited information is available on mucosal vaccine development for the elderly.

Conclusions:

• Nasal administration of CT may lead to CNS accumulation, raising safety concerns for human use.
• Aged mice exhibit immune dysregulation, indicating potential challenges for mucosal vaccine efficacy in the elderly.
• Further research is needed to address CT toxicity and optimize mucosal vaccine strategies for diverse populations.