IKKβ-induced inflammation impacts the kinetics but not the magnitude of the immune response to a viral vector.

Microbial adjuvants in vaccines activate key transcription factors, including NF-κB and interferon response factors (IRFs). However, the individual role of these transcription factor pathways in promoting adaptive immunity by adjuvants is not clear. It is widely believed that induction of a strong inflammatory response potentiates an adaptive immune response. In this study, we sought to determine whether activation of the pro-inflammatory inhibitor of κB kinase β (IKKβ) canonical NF-κB pathway promoted vaccine-induced immune responses. An adenovirus expressing constitutively activated IKKβ (AdIKK) induced robust DC maturation and high expression of key cytokines compared with a control virus. In vivo, AdIKK triggered rapid inflammation after pulmonary infection, increased leukocyte entry into draining LNs, and enhanced early antibody and T-cell responses. Notably, AdIKK did not influence the overall magnitude of the adaptive immune response. These results indicate that induction of inflammation by IKKβ/NFκB in this setting impacts the kinetics but not the magnitude of adaptive immune responses. These findings therefore help define the individual role of a key pathway induced by vaccine adjuvants in promoting adaptive immunity.