Abstract 15697: Exposure to Serum From Exclusive Heated Tobacco Product Smokers Induces mTOR Activation and Fibrotic Features in Human Cardiac Fibroblasts
Vittorio Picchio, Francesca Pagano, Roberto Carnevale, Alessandra D'Amico, Claudia Cozzolino, Erica Floris, Antonella Bordin, Leonardo Schirone, Wael Saade, Fabio Miraldi, Elena De Falco, Mariangela Peruzzi, Sebastiano Sciarretta, Giuseppe Biondi-Zoccai, Giacomo Frati, Isotta Chimenti- Physiology (medical)
- Cardiology and Cardiovascular Medicine
Introduction: Smokers are at higher risk of fibrosis-related atrial fibrillation. The use of heated tobacco products (HTPs) is rising worldwide with unclear effects on health. The SUR-VAPES chronic trial showed that exclusive HTP smokers have increased serum markers of oxidative/endothelial stress versus non-smokers (NS), comparable to cigarette smokers.
Hypothesis: We hypothesized that the serological profile of HTP smokers can activate atrial fibroblasts towards a pro-fibrotic phenotype.
Methods: CFs were isolated from discarded atrial tissue from elective cardiac surgery procedures, and exposed to serum lots (20 healthy young subjects each) from HTP smokers (mean exclusive use=1.5 years) or clinically matched NSs from the SUR-VAPES Chronic trial. ANOVA testing was applied.
Results: CFs treated with HTP serum increased expression of fibrotic genes, including PDGFA (1.18-fold, p<0.01) and THY1 (1.22-fold, p<0.01), and increased aSMA protein levels (1.87-fold, p<0.01), compared to NS serum. Connexin 43 was downregulated at both mRNA (1.17-fold, p<0.05) and protein levels (1.56-fold, p<0.01) in CFs after exposure to HTP serum versus NS. COL1A1 expression increased (1.46-fold, p<0.01), with higher soluble collagen release (1.56-fold, p<0.05). CFs pre-treated with HTP serum released lower levels of cardioprotective proteins (e.g. Adiponectin, Chi3L1, VEGF) by protein arrays/ELISA (p<0.05 vs NS). Paracrine support of CF-conditioned media to endothelial tube formation (63.3±4.7 vs 37.3±5.7 mesh #/well, p<0.05) and to cardiomyocyte viability under starvation (0.60±0.04 vs 0.47±0.01 normOD vs t0, p<0.001) were reduced when pre-treated with HTP versus NS serum. Array screening of 37 phospho-proteins in CFs exposed to HTP serum for 1h found several beneficial pathways blunted, with many inhibiting mTOR, including decreased P-PRAS40 (-2.43-fold) and P-p53 (-2.32-fold, p<0.05). Western blot analysis on CFs after 48h of HTP serum treatment confirmed increased P-mTOR (1.40-fold), and its targets P-S6K (1.39-fold) and P-4EBP1 (1.83-fold, all p<0.05).
Conclusions: The serological profile of chronic exclusive HTP smokers induces CF activation and fibrotic features pointing to a potential risk for atrial fibrosis.