Abstract:
Naked mole-rats (NM-R; Heterocephalus glaber) live in multi-generational
colonies with a social hierarchy, and show low cancer incidence and long
life-spans. Here we asked if an immune component might underlie such
extreme physiology. The largest lymphoid organ is the spleen, which
plays an essential role in responding to immunological insults and may participate
in combating cancer and slowing ageing. We investigated the
anatomy, molecular composition and function of the NM-R spleen using
RNA-sequencing and histological analysis in healthy NM-Rs. Spleen size
in healthy NM-Rs showed considerable inter-individual variability, with
some animals displaying enlarged spleens. In all healthy NM-Rs, the
spleen is a major site of adult haematopoiesis under normal physiological
conditions. However, myeloid-to-lymphoid cell ratio is increased and splenic
marginal zone showed markedly altered morphology when compared to
other rodents. Healthy NM-Rs with enlarged spleens showed potentially
better anti-microbial profiles and were much more likely to have a high
rank within the colony. We propose that the anatomical plasticity of the
spleen might be regulated by social interaction and gives immunological
advantage to increase the lifespan of higher-ranked animals.
