COPD-derived fibroblasts secrete higher levels of senescence associated secretory phenotype (SASP) proteins

Abstract

Recently, we found higher levels of cellular senescence in COPD-derived fibroblasts compared to controls. Senescent cells secrete (pro-inflammatory) proteins, called senescence associated secretory phenotype (SASP), which can contribute to tissue dysfunction. SASP composition is cell type specific and largely unknown for lung fibroblasts. Therefore, we aimed to determine SASP proteins of primary lung fibroblasts and assess if SASP protein levels are higher in COPD-derived fibroblasts compared to control. Cellular senescence was induced by Paraquat (PQ) treatment in fibroblasts from COPD patients and matched non-COPD controls. The Olink proteomics panels Inflammation and Cardiovascular III, were used to measure the secretion of 184 proteins, after 4 days of PQ. A 3-fold increase upon PQ was defined as SASP protein. Next, secreted levels of these SASP proteins were compared between COPD and non-COPD. FDR adjusted P Cellular senescence was increased upon PQ treatment (51% vs 16% SA-β-gal positivity). We identified 124 proteins as SASP proteins of primary lung fibroblasts, including several previously defined SASP proteins: GDF-15, IL-1α, MMP-9, and U-PAR. The levels of 42 SASP proteins were higher in COPD-derived fibroblasts compared to controls, including t-PA, U-PAR, NRTN, and IL12B. For the first time, 124 SASP proteins of senescent lung fibroblast were identified, of which 42 were higher in COPD-derived fibroblasts compared to controls. Interestingly, among these COPD-associated SASP proteins were proteins associated with chronic inflammation and extracellular matrix changes, suggesting a role for SASP proteins in the disease pathology of COPD.