Fig. 2. Specific monocyte clusters are associated
with ambient exposure to PM2.5 levels in healthy versus
asthmatic subjects. Computational analysis was performed on mass
cytometry data from PBMCs from 6-8 years old subjects exposed to low
versus high PM2.5 (N=25 including 15 healthy and 10
asthmatic subjects per group). Eight unsupervised distinct clusters were
identified using FlowSOM based on expression of phenotypic and
functional monocyte markers. Heatmap representing expression intensity
of each marker and the frequency of monocyte clusters (A). Data
visualization using Uniform Manifold Approximation and Projection (UMAP)
for dimension reduction demonstrated the neighborhood pattern of
monocyte clusters. The colors in the UMAP correspond to the colors of
the cluster IDs, as indicated in the heatmap. (B). Non-parametric
statistical analysis identified monocyte signatures significantly
associated with exposure to PM2.5 in children diagnosed
with or without asthma (C). P values, computed using
non-parametric Wilcoxon-rank sum test, indicate significance of
difference in frequency of circulating monocyte clusters from children
exposed to low and high levels of PM2.5.