Uncovering the Inflammatory-Fibrotic Axis in Pulmonary Sarcoidosis

PROJECT ABSTRACT Sarcoidosis is a systemic disease of unknown etiology that results in granulomatous inflammation which, if persistent, can lead to fibrosis of involved organs and subsequent dysfunction. Advanced pulmonary sarcoidosis-related fibrosis (APSF) occurs in up to 20% of those with pulmonary sarcoidosis and carries significant morbidity and mortality. Existing transcriptomic studies within sarcoidosis highlight multiple peripherally circulating dysfunctional cell subtypes and aberrant pathways that drive sarcoidosis inflammation; however, knowledge of these mechanisms in the APSF phenotype is limited. Improved understanding of the mechanisms by which dysregulated immunity contributes to APSF is critical to identify future therapeutic strategies that benefit this vulnerable population. Our preliminary data suggest that subsets of circulating CD14+ monocytes exhibit unique profibrotic programming in APSF compared to non-fibrotic disease, with further profibrotic signaling originating from circulating central memory T cells and deserves further exploration. By integrating current knowledge of sarcoidosis pathophysiology, emerging concepts in idiopathic pulmonary fibrosis (IPF), and our compelling preliminary data, we aim to elucidate the mechanisms through which circulating CD14+ monocytes drive the inflammatory-fibrotic axis of APSF. In Aim 1, we will use single- cell RNA sequencing (scRNA-seq) and surface protein indexing to identify key regulators and corresponding signaling pathways within subpopulations of CD14+ monocytes in individuals with chronic sarcoidosis, with and without APSF. Key transcription factors (TFs) identified will be tested in an in vitro functional assay of monocyte-to-fibrocyte differentiation to confirm their profibrotic effects. Aim 2 will define the external profibrotic influences monocytes receive from TCM cells leveraging pathways uncovered by scRNA-seq through in vitro methods of cell stimulation, co-culture, and differentiation assays. We anticipate that our findings will identify novel mechanistic pathways involved in the progression of APSF that may be used for therapeutic targeting. In addition, a complimentary career development plan has been proposed to achieve my goals of becoming an independent investigator and future expert in pulmonary fibrosis immunology. Over the award period, I will refine analytical techniques of large, multifaceted datasets and strengthen my expertise in translating gained insights into biologically relevant in vitro models. Through this process, I will also advance my skills in study design, statistical methods, and result dissemination, building a strong foundation for future R01 funding as a independent physician scientist. 1 | Uncovering the Inflammatory-Fibrotic Axis in Pulmonary Sarcoidosis Christen Vagts, MD Project Abstract and Narrative