Alveolar macrophages (AM) are differentially regulated by human surfactant protein-A (SP-A)1 or SP-A2. However, AM are very heterogeneous and differences are difficult to characterize in intact cells. Using the Toponome Imaging System (TIS), an imaging technique that uses sequential immunostaining to identity patterns of biomarker expression or combinatorial molecular phenotypes (CMP), we studied individual single cells and identified subgroups of AM (n=168) from SP-A knockout (KO) mice and mice expressing either SP-A1 or SP-A2. The effects, as shown by CMPs, of SP-A1 and SP-A2 on AM were significant and differed. SP-A1 AM were the most diverse and shared the fewest CMPs with KO and SP-A2. Clustering analysis of each group showed three clusters where the CMP-based phenotype was distinct in each cluster. Moreover, a clustering analysis of all 168 AM revealed ten clusters, many dominated by one group. Some CMP, overlap among groups was observed with SP-A2 AM sharing the most CMPs and SP-A1 AM the fewest. The CMP-based patterns identified here provide a basis for not only understanding AM diversity, but, most importantly, the molecular basis for the diversity of functional differences in mouse models where the impact of genetics of innate immune molecules on AM has been studied.
David S. Phelps, Vernon M. Chinchilli, Judith Weisz, Lili Yang, Debra Shearer, Xuesheng Zhang, Joanna Floros