A109-06 Comprehensive Profiling of Peripheral Blood Mononuclear Cell Surface Markers in Idiopathic Pulmonary Fibrosis via Mass Cytometry

Abstract Rationale Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease with a poor prognosis, characterized by median survival of 3-5 years from diagnosis. Despite the availability of antifibrotic therapies, disease progression remains highly variable among patients, and reliable biomarkers for risk stratification are urgently needed. While lung-resident immune cells have been extensively studied, emerging evidence suggests that systemic immune dysregulation may contribute to IPF pathogenesis. However, comprehensive characterization of circulating immune cell populations and their relationship to clinical outcomes remains limited. Mass cytometry enables high-dimensional single-cell profiling, allowing simultaneous measurement of over 40 parameters to identify rare immune cell subsets. This study aimed to comprehensively profile peripheral blood mononuclear cells (PBMCs) in IPF patients using mass cytometry and identify specific immune cell subsets associated with disease progression and survival. Methods PBMCs were isolated from 16-IPF patients diagnosed according to international guidelines and 6-healthy controls. Cells were stained with a panel of 40-metal-conjugated antibodies targeting lineage markers, activation markers, and chemokine receptors. Mass cytometry data were analyzed using unsupervised clustering algorithms and dimensionality reduction techniques to identify distinct immune cell populations, resulting in 34-unique clusters. Statistical analyses compared cluster frequencies between IPF patients and controls, as well as between patients with progressive disease (defined by ≥ 10% decline in forced vital capacity FVC or death within 12 months) and stable disease. Correlation analyses examined relationships between immune subset frequencies and clinical parameters including pulmonary function decline and overall survival. Results Among 34-identified clusters, 11 showed significantly elevated frequencies in IPF patients compared to controls(p 0.05), with many demonstrating increased CCR4 expression. Detailed analysis of the CCR7+CD45RA+CD4+T cell population(naïve-like CD4+ T cells) revealed substantial heterogeneity in CD38 expression. IPF patients exhibited significantly higher frequencies of CD38low naïve-like CD4+T cells compared to controls(p = 0.008), which were further elevated in progressive versus stable IPF(p = 0.032). The frequency of CD38low naïve-like CD4+T cells showed strong correlation with 1-year decline in percent predicted FVC(%FVC) (r = 0.873, p = 0.019). In multivariable Cox regression analysis adjusted for age, sex, and baseline %FVC, higher frequencies of this subset were independently associated with shorter overall survival(hazard ratio=1.23 per 1% increase, p = 0.027). Conclusion This comprehensive mass cytometry study identified multiple immune cell subsets with altered frequencies in IPF patients. Most notably, CD38low naïve-like CD4+T cells emerged as a novel biomarker strongly associated with disease progression and survival. This immune subset may represent a dysfunctional or immunosenescent phenotype contributing to IPF pathogenesis and warrants further investigation as a potential therapeutic target. This abstract is funded by: None