The Mysterious Case of Pulmonary Fibrosis: A Pursuit of Immune and Matrix Factors in Pulmonary Fibrosis

Interstitial lung diseases are a diverse group of pathologies with different etiologies, but share a common characteristic: the accumulation of stiff scar tissue (fibrosis) that ultimately leads to lung failure and death. Fibroblasts are responsible for repairing damaged lung tissue, but in disease these cells become aberrantly activated myofibroblasts that perpetually generate unnecessary scar tissue. Although myofibroblasts synthesize this scar, pulmonary fibrosis progresses due to a coordinated, multi-faceted process where myofibroblasts are instructed by both biochemical and biophysical cues from their surrounding extracellular matrix (ECM) as well as neighboring cells. Notably, clinical evidence underscores the correlation between specific immune expression profiles, cell types, and lung fibrosis outcomes. Similarly, enlargement of the lung-draining lymph nodes, the site of immune education, is associated with increased patient mortality; however, it is unknown whether this lymph node remodeling is a pro-fibrotic mechanism or an attempt to mount a beneficial immune response. To address these gaps, this thesis aims to identify “anti-fibrotic” and “pro-fibrotic” immune cell populations and examine the impact of ECM remodeling in lymph nodes on immune phenotypes linked to adverse outcomes in pulmonary fibrosis. In this dissertation, I first leveraged single cell RNA sequencing of circulating immune cells from patients exhibiting early-, late-, and non-resolving fibrotic remodeling in the lung, an analysis enabled by the SARS-CoV2 outbreak, to identify immune phenotypes associated with the suppression or promotion of pulmonary fibrosis progression. I then developed an advanced tissue analysis workflow that integrates deep multiplex imaging and atomic force microscopy. This innovative approach aligns crucial cellular biology with the chemo-mechanical properties of the ECM in distinct spatial regions of patient lymph nodes. The insights gained from this comprehensive analysis offer a deeper understanding of lung fibrosis-related lymph node remodeling in this enigmatic disease.