Table of Contents
Comparing rejection to other scarring lung diseases
The scientists discovered a rogue cell type (KRT17 and KRT5 cells) that drives lung scarring across multiple diseases, including idiopathic pulmonary fibrosis, interstitial lung disease, COPD, COVID-19 lung damage and transplant rejection. By integrating data from this array of scarring lung diseases, the scientists created the first comprehensive reference map showing which molecular features are shared across conditions and which are unique to each disease.
“By comparing chronic rejection to other scarring lung diseases, we identified both shared and unique features,” said Bharat, who also is a member of the Robert H. Lurie Comprehensive Cancer Center of Northwestern University. “This means treatments developed for one condition might help others. The benefits extend far beyond transplant patients.”
The scientists also identified previously unrecognized cell populations in rejected lungs. These include “exhausted” T cells (which participate in immune response) that remain activated but dysfunctional, and “super-activated” macrophages (immune cells that act like the body’s “clean-up crew”) that promote inflammation and scarring.
Lastly, the scientists developed new computational methods to analyze data from multiple studies together, overcoming technical barriers that previously prevented this kind of comprehensive analysis, Bharat said.
New drug targets identified
The scientists pinpointed specific genes and signaling pathways (like PDGF, GDF15 and TWEAK) that drive scarring, which allows them to identify potential targets for new drugs, Bharat said. Some existing medications, such as nintedanib (sold under the brand names Ofev and Vargatef), and pirfenidone (commonly sold under the brand name Esbriet), which are approved for other lung diseases, might be repurposed for transplant rejection, he said.
“The findings have immediate translational potential,” Bharat said. “We’re already exploring therapeutic strategies based on these discoveries.”
Broad impact on pulmonary fibrosis
While addressing CLAD was the main focus of the paper, this research has major implications for understanding and treating all forms of pulmonary fibrosis, Bharat said.
“The molecular pathways and cell types we identified are relevant to conditions affecting hundreds of thousands of patients with various lung-scarring diseases, not just transplant recipients,” Bharat said. “This work essentially provides a ‘Rosetta Stone’ for understanding lung scarring regardless of the initial trigger.”
Other Northwestern study authors include Dr. Yuanqing Yan, Taisuke Kaihou, Emilia Lecuona, Xin Wu, Masahiko Shigemura, Haiying Sun, Chitaru Kurihara, Ruli Gao, Felix L Nunez and G. R. Scott Budinger.
Funding for the study was provided by the National Institutes of Health.
