An aberrant immune-epithelial progenitor niche drives viral lung sequelae

Area of Science:

• Immunology
• Pulmonology
• Pathology

Background:

• Post-acute sequelae of SARS-CoV-2 (PASC), or Long COVID, presents significant public health challenges.
• The underlying cellular and molecular mechanisms of PASC, particularly lung fibrosis, are not well understood.
• Abnormal immune responses and impaired organ recovery are implicated in PASC pathogenesis.

Purpose of the Study:

• To elucidate the mechanisms driving lung fibroproliferation in respiratory PASC.
• To identify therapeutic targets for mitigating long-term lung damage after viral pneumonia.
• To establish a relevant preclinical model for studying PASC-associated lung disease.

Main Methods:

• Analysis of three patient cohorts with respiratory PASC.
• Development and utilization of a mouse model for post-viral lung disease.
• Spatial transcriptomics and advanced imaging techniques.
• Investigated CD8+ T cell-macrophage interactions and cytokine signaling (IFNγ, TNF, IL-1β).

Main Results:

• Identified a unique immune-epithelial progenitor niche driving fibrosis in respiratory PASC.
• Demonstrated that lung-resident CD8+ T cell-macrophage interactions impair alveolar regeneration.
• Showcased that IFNγ and TNF from CD8+ T cells induce chronic IL-1β release from macrophages, maintaining dysplastic progenitors and fibrosis.
• Therapeutic neutralization of IFNγ+TNF or IL-1β significantly improved alveolar regeneration and lung function.

Conclusions:

• Aberrant CD8+ T cell-macrophage crosstalk is a key driver of lung fibrosis in PASC.
• Targeting the IFNγ-TNF-IL-1β axis offers a promising therapeutic strategy for PASC-related lung disease.
• This study highlights interventions for established fibrotic disease, addressing a critical unmet clinical need.