Cellular heterogeneity of human fallopian tubes in normal and hydrosalpinx disease states identified by scRNA-seq

Abstract

Fallopian tube (FT) homeostasis requires dynamic regulation of heterogeneous cell populations and is disrupted in infertility and ovarian cancer. Here we applied single-cell RNAseq to profile 53,376 FT cells from 3 healthy pre-menopausal subjects. The resulting cell atlas contains 12 major cell types representing epithelial, stromal and immune compartments. Re-clustering of epithelial cells identified 4 ciliated and 6 non-ciliated secretory epithelial subtypes, two of which represent potential progenitor pools: one leading to mature secretory cells, while the other contributing to either ciliated cells or one of the stromal cell types. To understand how FT cell numbers and states change in a disease state, we analyzed ~15,000 cells from a hydrosalpinx sample and observed shifts in epithelial and stromal populations, and cell type-specific changes in extracellular matrix and TGF-β signaling, underscoring fibrosis pathophysiology. This resource is expected to facilitate future studies to understand fallopian tube homeostasis in normal development and disease.

Single-cell Total RNA Miniaturized sequencing (STORM-seq) reveals differentiation trajectories of primary human fallopian tube epithelium

“…Secretory cells represent the largest fraction of cells across both patients (∼58%), mimicking the expected proportion in vivo . Within our data we observe the previously defined expression patterns distinguishing secretory cells from other cell types within the FTE ( EPCAM, PAX8, KRT7 , and OVGP1 ) ( Figure 4B ; Supplemental table 1 ) 16,18,19 . Top marker genes for the secretory clusters (clusters 5 and 7) include ovarian cancer-related genes ( MSLN ) and regulators of Wnt-signaling ( RSPO1 ) ( Figure 4C ).…”

“…Interestingly, this expression level varied by cluster. Additionally, secretory (PAX8, KRT7), ciliated (FOXJ1, CCDC17, CCDC78), and EpCAM+ infiltrating immune (CD45, ITGAX/CD11c, CD14) cells were also identified (Figure 3A), consistent with prior work 16,18,19,25 . However, we were not able to readily identify cell clusters corresponding to the less well-defined 'peg' cells using markers from a prior study 26 (EpCAM, CD44, ITGA6) within or across patients (Supplemental Figures 9).…”

“…Others 16 also identified a similar population of cells simultaneously expressing epithelial, EMT, and endothelial markers, and performed co-expression studies in tissue sections to identify whether these markers are found within the same cell or on different cells. Indeed, their results demonstrate that the epithelial:EMT and epithelial:endothelial markers can be co-expressed in the same cells 16 . Further, the EpCAM cell surface fluorescence index sort information from our data also confirm that these singlet cells express EpCAM on the cell surface, suggesting that they are not endothelial in origin ( Supplemental Figure 9 ).…”

“…However, these cells are poorly understood. Another cell type, dubbed 'basal' 17 or 'reserve' cells, is even less well characterized, recently proposed to likely represent resident immune cells [16][17][18][19][20] .…”

“…Well-established and characterized cell types in this epithelial layer include ciliated cells (FOXJ1+/CAPS+) and secretory cells (PAX8+/KRT7+) [13][14][15] . Additional cell types have been described 16 , but less consistently. For example, intercalated 'peg' cells, characterized as EPCAM+/CD44+/ITGA6+, were proposed as stem-like or progenitor cells for the epithelial compartment 15 .…”