Eosinophils and White Fat: Protection from worms and inflammaging

Pro-inflammatory alterations of white adipose tissue (WAT) with increasing age play an important role in mammalian aging. WAT produced eotaxin-1 [CCL11--C-C motif chemokine ligand 11) and MCP-1 [CCL2 (C-C motif chemokine ligand 2] are elevated in old mammals. Obese and old adipose tissue produce excessive pro-inflammatory cytokines such as IL-6, CCL2 and IL1-beta that contribute to inflammaging. WAT-based inflammaging involves an altered homeostatic equilibrium between pro-inflammatory cells such as activated Type 1 macrophages, B (high IgJ) and T cells and anti-inflammatory eosinophils and Tregs. Specifically, young and lean individuals exhibit a high eosinophil-to-macrophage ratio with an enrichment of alternative activated tissue macrophages which is reduced in the WAT of aging mice. Eosinophils from young animals adoptively transferred to old mice, home to WAT and reverse many of the immunoinflammatory signatures associated with aging. Whether eosinophil-based therapies for inflammaging could be created remains an open question.