Reduced Expression of the DNA-Binding Protein ARID3a, a Mediator of Human Hematopoiesis, in Hematopoietic Progenitors Contributes to Age-Related Transcriptional Changes

Abstract

Abstract Population studies estimate that 40% of European and US populations will be over the age of 60 by 2050. Aged individuals exhibit impaired immune responses consisting of poor responses to vaccines and increases in myeloid lineage cells. The reasons for decreased immunity in the elderly haven’t been completely elucidated, making studies of the mechanisms leading to these poor responses important. One possibility is that defects in early hematopoiesis may contribute to poor immune responses in the elderly. Previous studies in our lab indicated that inhibition of the DNA-binding protein ARID3a in hematopoietic cultures of human cord blood led to hematopoietic developmental skewing toward myeloid lineage rather than lymphoid lineage progenitors. Furthermore, we previously reported that numbers of ARID3a-expressing hematopoietic stem cells (HSCs) can be highly variable in some patient subsets as well as in healthy individuals. ARID3a expression levels in hematopoietic progenitor cells have not previously been analyzed in relationship to age. We hypothesized that alterations in ARID3a expression levels in early hematopoietic progenitors could contribute to poor immune responses observed in elderly people. Our data suggest that hematopoietic progenitors obtained from peripheral blood of aged healthy persons show decreased frequencies of ARID3a-expressing HSCs in comparison to HSCs from young individuals. Furthermore, lineage committed progenitor numbers were also altered in aged persons compared young people. Ongoing analyses to investigate the gene expression data in young and aged HSCs in relation to ARID3a expression will assess potential genes regulated by ARID3a that contributes to lineage commitment and development.