Neutrophil extracellular traps as immunofibrotic mediators in RA-ILD; pilot evaluation of the nintedanib therapy

Front Immunol. 2024 Oct 23:15:1480594. doi: 10.3389/fimmu.2024.1480594. eCollection 2024.

Abstract

Objective: Rheumatoid arthritis-associated interstitial lung disease (RA-ILD) is a significant pulmonary complication of RA. This study tried to elucidate the mechanisms enhancing inflammation and causing lung injury in RA-ILD, focusing on the role of neutrophil extracellular traps (NETs). The study also investigated the potential benefits of nintedanib in advanced disease.

Methods: Nine RA-ILD patients and nine healthy controls were included in the study. Inflammatory markers in patients' circulation were evaluated with immunoassays. The formation of NETs was examined using a citrullinated histone H3 (CitH3) ELISA and cell immunofluorescence. Inflammatory proteins expressed in neutrophils/NETs were studied with real-time qPCR and NET ELISA. To assess the effect of nintedanib, an intracellular tyrosine kinase inhibitor with antifibrotic properties, in RA-ILD a paired study was conducted in five patients before treatment administration and 16 weeks later.

Results: The soluble terminal complement complex sC5b-9 and the levels of CitH3 were significantly elevated in patients with RA-ILD, compared to healthy controls. In addition, neutrophils isolated from RA-ILD patients released NETs enriched with tissue factor and interleukin-17A. Inflammatory NETs had a dynamic role, increasing the fibrotic potential of human pulmonary fibroblasts (HPFs). On the other hand, nintedanib treatment decreased NETs and sC5b-9 levels in RA-ILD patients.

Conclusion: The findings propose an interplay between circulating NETs and HPFs, establishing the immunofibrotic aspects of RA-ILD. They also support the effectiveness of nintedanib in reducing key pathological processes of the disease. Further research is needed to fully understand these mechanisms and optimize treatment strategies for RA-ILD.

Keywords: fibroblasts; interleukin-17A; neutrophil extracellular traps; nintedanib; rheumatoid arthritis-interstitial lung disease; terminal complement complex; tissue factor.

MeSH terms

  • Aged
  • Arthritis, Rheumatoid* / blood
  • Arthritis, Rheumatoid* / drug therapy
  • Arthritis, Rheumatoid* / immunology
  • Biomarkers
  • Extracellular Traps* / drug effects
  • Extracellular Traps* / immunology
  • Extracellular Traps* / metabolism
  • Female
  • Fibroblasts / drug effects
  • Fibroblasts / metabolism
  • Histones / metabolism
  • Humans
  • Indoles* / pharmacology
  • Indoles* / therapeutic use
  • Lung Diseases, Interstitial* / blood
  • Lung Diseases, Interstitial* / drug therapy
  • Lung Diseases, Interstitial* / etiology
  • Lung Diseases, Interstitial* / immunology
  • Male
  • Middle Aged
  • Neutrophils* / immunology
  • Neutrophils* / metabolism
  • Pilot Projects

Substances

  • nintedanib
  • Indoles
  • Biomarkers
  • Histones

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. The research work was supported by the Hellenic Foundation for Research and Innovation (HFRI) under the 5th Call for HFRI PhD Fellowships (Fellowship Number: 20842).