Fig. 8: Age-associated expression of S100A8/A9 in B lymphocytes.
A, B UMAP of BM B cell clusters from aged healthy human subjects from two external single-cell studies and the average expression of S100A8 and S100A9 across clusters. The red dashed lines mark an average expression level of 0.1%. The error bar shows a 95% confidence interval. C Age-associated expression of S100A8/A9 in mouse B cells from a mixture of tissues as measured based on scRNA-seq data. SCC, Spearman’s correlation coefficient. D Age-associated expression of S100a8/a9 in the BM B cells of C57BL/6J female mice as measured by qPCR. Y, young (3 m); M, middle age (12 m); O, old (22 m). The error bars represent the standard error. Two independent samples t-test (two-sided), *, p < 0.05; **, p < 0.01. E The average expression level of three ABC marker genes (TBX21, ITGAM, and ITGAX) across B cell subpopulations. F TBX21 regulon specificity score comparison across B cell subpopulations. G ELISA assay demonstrating the ability to secrete S100A8/A9 for human BM B cells. The subjects’ ages range from 56 to 66. The concentration of S100A8/A9 in the cell culture medium was measured at four time points (12 h, 1 d, 2 d and 4 d) for each sample. ARH-77 and blank culture medium were used as negative controls, while the unsorted human BMMC was used as a positive control. H Chord diagram showing the predicted S100A8/A9-TLR4 signaling between B cell subpopulations and surrounding bone marrow non-B cell types. I Schematic diagram demonstrating the occurrence of S100A8hi B cells in the aged population and how they participate in the inflammageing process.
