The immune system recognizes flagellin as foreign, provoking an increased immune response when immunized with flagellin. This has been tested in humans as a vaccine adjuvant to enhance vaccine effectiveness. Immunization with flagellin has also been shown to improve gut microbiome function and reduce systemic inflammation in mice and human self-experimentation. Researchers have now demonstrated a modest extension of life span in mice resulting from repeated flagellin immunization starting in late life. The fusion protein made up of flagellin and another bacterial protein was used, showing potential for improving long-term health and longevity through immunization.
TLR5 activation via mucosal delivery of a flagellin-containing fusion protein effectively extends the lifespan and enhances the healthspan of aged mice of both sexes. This enhancement in healthspan is evidenced by diminished hair loss and ocular lens opacity, increased bone mineral density, improved stem cell activity, delayed thymic involution, heightened cognitive capacity, and the prevention of pulmonary fibrosis. Additionally, this fusion protein boosts intestinal mucosal integrity by augmenting the surface expression of TLR5 in a certain subset of dendritic cells and increasing interleukin-22 (IL-22) secretion.
