Fig. 3. Lymphoid cells skew towards an IL-17-expressing phenotype in aging.

a, Violin plots comparing the expression values of Il17a and Il17f in aged and adult CD4⁺ T_H cells, γδ T cells and ILCs. b, Immunofluorescence staining of IL-17A in adult (upper left) and aged (lower left) mouse back skin. Scale bars, 50 μm. Insets, higher-magnification images focusing on the dermis (right). Scale bars, 20 μm. White arrows indicate positive cells. For enhanced visualization, brightness and contrast were adjusted on these images. n = 6 adult mice and n = 5 aged mice collected in two independent experiments. Quantification is presented as the percentage of dermal positive cells. c, UMAP representation of subclustering of previously described CD4⁺ T_H cell and γδ T cell clusters. Three new clusters of CD4⁺ T_H cells were found (CD4⁺ T_H(a–c)), shown here in blue and circled by the continuous line; and two new clusters of γδ T cells were found (γδ T(a) and T(b)), in green and circled by the dashed line. d, List of relevant markers discriminating subclusters belonging to specific CD4⁺ T_H cell subtypes. e, Boxplots depicting changes in the proportion of CD4⁺ T_H cell subclusters between aged and adult dermis, performed with sccomp⁸¹ and obtained using scRNA-seq data. Error bars indicate 95% credible intervals and center line is the median. Black boxplots represent the observed data while blue ones indicate the posterior predictive check of the model. Boxes colored orange indicate statistically significant differences in cell proportion between conditions (FDR < 0.025 using Benjamini–Hochberg procedure to control for multiple testing). f, List of relevant markers discriminating subclusters belonging to specific γδ T cell subtypes. g, Boxplots depicting changes in the proportion and γδ T cell subclusters between aged and adult dermis, performed with sccomp⁸¹ and obtained using scRNA-seq data. Error bars indicate 95% credible intervals and center line is the median. Black boxplots represent the observed data while blue ones indicate the posterior predictive check of the model. Boxes colored orange indicate statistically significant differences in cell proportion between conditions and red triangles mark outliers. h, Violin plots showing expression values of Tmem176a and Tmem176b in comparison of adult and aged ILCs. e,g, Where differences in cell proportion between ages were significant, the boxplot is marked in orange.