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Researchers investigated how lung blood vessel cells respond to hemin, a blood molecule released during red blood cell breakdown in sickle cell disease. They found that hemin triggers the formation of protective fat droplets (lipid droplets) inside these cells, and when fat droplet formation was blocked, cells showed increased death, inflammation markers (IL-6 and IL-8), and stress. Conversely, boosting fat droplet formation with oleic acid improved cell survival and reduced inflammatory responses and mitochondrial oxidative stress.
Why it matters
This discovery reveals a potential protective mechanism that lung blood vessel cells use to survive the toxic effects of hemin in sickle cell disease. Understanding this fat droplet defense system could lead to new therapeutic approaches that enhance this natural protective response to reduce lung complications in patients with sickle cell disease and other conditions involving blood cell breakdown.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Sickle cell disease (SCD) is characterized by chronic and episodic hemolysis, inducing endothelial cell dysfunction and death. Lipid droplets (LDs) accumulate intracellularly in response to stress but the role of LDs in hemin-stressed pulmonary microvascular cells remain unexplored. We hypothesized that LD formation is an adaptive response that improves endothelial cell survival during hemin-induced stress. We utilized cultures of human lung microvascular endothelial cells (hLMVECs) to test this hypothesis. Hemin alone was able to induce LD biogenesis in culture. In response to hemin treatment, we found an increase in cellular death by lactate dehydrogenase (LDH) assay when LD biogenesis was inhibited with a small molecule inhibitor of diacylglycerol acyltransferase 1 (DGAT1), A922500. Induction of LDs by treatment with oleic acid (OA) coupled with hemin resulted in improved endothelial cell survival. Hemin treatment was able to activate p-JNK and p-P38 signaling, while treatment with OA alone could not induce either signaling pathway. Hemin treatment combined with DGAT1 inhibition resulted in an increase in endothelial cell secreted IL-6 and IL-8 levels as measured by enzyme linked immunosorbent assay (ELISA), demonstrating an increase in endothelial cell dysfunction and stress. Induction of LD formation with oleic acid (OA) treatment resulted a reduction in secreted IL-6 and IL-8. Mitochondrial reactive oxygen species (ROS) production was decreased by OA treatment, as evidenced by MitoSOXRed assay. These data suggest that hLMVECs are protected from hemin-induced inflammation and death by the presence of LDs. Further studies are needed to explore the Hemin-LD-Cell Death axis for translational therapeutic use.
Source: Hemin Triggers Cytoprotective Lipid Droplet Formation in Pulmonary Microvascular Endothelial Cells