# Single-cell transcriptomic analysis of endometriosis provides insights into fibroblast fates and immune cell heterogeneity

## TL;DR

This study uses single-cell analysis to explore endometriosis, revealing fibroblast roles and immune cell changes that may explain the disease's development.

## Contribution

The study provides a single-cell transcriptome atlas of endometriosis, identifying fibroblast subpopulations and immune cell heterogeneity linked to the disease.

## Key findings

- Fibroblast subpopulations and a developmental trajectory were identified in endometriosis.
- T cells in endometriosis were less activated, while monocytes/macrophages increased in lesions.
- Cell-cell interactions showed an imbalanced immune environment promoting endometriosis.

## Abstract

Endometriosis is an oestrogen-dependent disease with an unclear aetiology and pathogenesis affecting 6–10% of the global female population, predominantly those of reproductive age. Herein, we profile the transcriptomes of approximately 55,000 single cells from three groups including ectopic endometrium, eutopic endometrium from women with endometriosis, and eutopic endometrium from healthy women to create a single-cell transcriptome atlas of endometriosis.

We have identified 9 cell types and performed single-cell analysis of fibroblasts, and determined a potential developmental trajectory associated with endometriosis. We also identified fibroblast subpopulations related to endometriosis development and found that StAR played an important role in this process. Moreover, T cells in endometriosis were less activated or inflammatory with decreased effector CD8 + T cells, while the composition ratio of natural killer cells decreased and the percentage of monocytes/macrophages increased in endometriosis cysts. In addition, the effectiveness of immune cells in endometriosis lesions, eutopic endometrium from women with endometriosis, and eutopic endometrium from healthy women was distinct. Cell–cell interaction analyses highlighted the imbalanced immune environment in endometriosis lesions and immune cells in endometriosis could promote the development of the disease.

Our study provided a systematic characterisation of endometriosis and insights into the aetiology and pathology of endometriosis.

The online version contains supplementary material available at 10.1186/s13578-021-00637-x.