Complement-containing small extracellular vesicles from adventitial fibroblasts induce proinflammatory and metabolic reprogramming in macrophages

• Published in: JCI insight 2021-11, Vol.6 (21)
• Main Authors: Kumar, Sushil, Frid, Maria G, Zhang, Hui, Li, Min, Riddle, Suzette, Brown, R Dale, Yadav, Subhash Chandra, Roy, Micaela K, Dzieciatkowska, Monika E, D'Alessandro, Angelo, Hansen, Kirk C, Stenmark, Kurt R
• Format: Article
• Language: English
• Subjects: Animals; Cellular Reprogramming - genetics; Disease Models, Animal; Extracellular Vesicles - genetics; Fibroblasts - metabolism; Humans; Hypertension, Pulmonary - physiopathology; Inflammation; Macrophages - metabolism; Mice; Pulmonology
• ISSN: 2379-3708; 2379-3708
• DOI: 10.1172/jci.insight.148382

Pulmonary hypertension (PH) is a severe cardiopulmonary disease characterized by complement-dependent, fibroblast-induced perivascular accumulation and proinflammatory activation of macrophages. We hypothesized that, in PH, nanoscale-sized small extracellular vesicles (sEVs), released by perivascular/adventitial fibroblasts, are critical mediators of complement-dependent proinflammatory activation of macrophages. Pulmonary adventitial fibroblasts were isolated from calves with severe PH (PH-Fibs) and age-matched controls (CO-Fibs). PH-Fibs exhibited increased secretion of sEVs, compared with CO-Fibs, and sEV biological activity was tested on mouse and bovine bone marrow-derived macrophages (BMDMs) and showed similar responses. Compared with sEVs derived from CO-Fibs, sEVs derived from PH-Fibs (PH-Fib-sEVs) induced augmented expression of proinflammatory cytokines/chemokines and metabolic genes in BMDMs. Pharmacological blockade of exosome release from PH-Fibs resulted in significant attenuation of proinflammatory activation of BMDMs. "Bottom-up" proteomic analyses revealed significant enrichment of complement and coagulation cascades in PH-Fib-sEVs, including augmented expression of the complement component C3. We therefore examined whether the PH-Fib-sEV-mediated proinflammatory activation of BMDMs was complement C3 dependent. Treatment of PH-Fibs with siC3-RNA significantly attenuated the capacity of PH-Fib-sEVs for proinflammatory activation of BMDMs. PH-Fib-sEVs mediated proglycolytic alterations and complement-dependent activation of macrophages toward a proinflammatory phenotype, as confirmed by metabolomic studies. Thus, fibroblast-released sEVs served as critical mediators of complement-induced perivascular/microenvironmental inflammation in PH.