# Neutrophil-Fibroblast Crosstalk Drives Immunofibrosis in Sequelae of Pelvic Inflammatory Disease Through Neutrophil Extracellular Traps

## TL;DR

This study explores how neutrophils and fibroblasts interact to cause tissue scarring in pelvic inflammatory disease, focusing on the role of neutrophil extracellular traps.

## Contribution

The paper reveals a novel mechanism involving neutrophil-fibroblast crosstalk and autophagy-driven extracellular traps in pelvic tissue fibrosis.

## Key findings

- Autophagy promotes the formation of neutrophil extracellular traps (NETs) in SPID.
- NETs inhibit fibroblast apoptosis and promote their migration and proliferation.
- NETs contribute to immunofibrosis and tissue adhesion in pelvic inflammatory disease.

## Abstract

Due to the complex pathogenesis of sequelae of pelvic inflammatory disease (SPID), targeted therapeutic agents are still lacking. Here, we investigated the interactions between neutrophils and uterine fibroblasts (FBs) in developing tissue fibrosis in SPID.

A rat model of SPID was constructed to assess the roles of autophagy and neutrophil extracellular traps (NETs) in SPID rats. Single-cell sequencing data from the public database GSE223639 were utilized to identify the specific cell cluster FBs where NETs act. A DMSO-induced HL-60-driven neutrophil-like (dHL-60) cell model was established, and neutrophil-like cells were treated with rapamycin and MHY1485 to activate and inhibit autophagy, respectively, to observe the differences in the production of NETs. NETs were cocultured with FBs to observe the effects on FB proliferation, migration, apoptosis, and phenotypic transformation.

In vivo experiments revealed that there was a consistency in the expression of autophagy and NETs in the adherent tissues of rats with the SPID model and that autophagy promotes the generation of NETs, which are collectively involved in the fibrosis of pelvic tissues in SPID. Single-cell sequencing identified FBs, the cells in which NETs play a major role in aseptic inflammation. Further in vitro studies confirmed that NETs inhibit FB apoptosis while promoting horizontal and longitudinal migration, phenotypic transformation, and hyperproliferation of FBs, thereby exacerbating tissue fibrosis.

Autophagy promotes the generation of NETs, which facilitates FB transformation and hyperproliferation and exacerbates the degree of adhesion and fibrosis in the pelvic tissue of SPID.