研究脂肪幹細胞外泌體在懸浮微粒和缺血/再灌流引發的心臟損傷中對粒線體功能和細胞凋亡的影響

Abstract

流行病學研究顯示，細顆粒物（particulate matter, PM）暴露與心血管疾病之間存在密切關聯。然而，目前尚不清楚PM是否會加重心肌缺血/再灌流（ischemia/reperfusion, I/R）損傷，以及相關的機制。本研究探討PM暴露對I/R誘導的心臟損傷的影響，並分析脂肪幹細胞來源的外泌體（adipose stem cell-derived exosome, ADSC-Exo）中高含量的miR-221/222的潛在作用。使用miR-221/222基因剔除（KO）和miR-221/222過表達基因（TG）小鼠模型，進行10 mg/kg PM的氣管內注射處理。24小時後，小鼠接受左冠狀動脈結紮30分鐘後，進行3小時的再灌注（I/R）。在體外實驗，H9c2細胞前處理PM（50 µg/mL）並於1% O2缺氧環境下培養6小時，然後在正常氧氣環境培養12小時（hypoxia/reoxygenation, H/R）。結果顯示，PM加重了I/R（或H/R）引起的心臟損傷，通過增加活性氧化物（reactive oxygen species, ROS）和引發粒線體功能障礙，導致粒線體分裂相關蛋白（Drp1和MFF）及粒線體自噬相關蛋白（BNIP3和LC3B）的表達增加。ADSC-Exo或miR-221/222 mimics的治療顯著減少了PM+I/R誘導的心臟損傷。值得注意的是，ADSC-Exo中的miR-221/222直接調節BNIP3、LC3B和PUMA並減少其表達，最終降低細胞的粒線體自噬和細胞凋亡反應。本研究發現ADSC-Exo通過miR-221/222/BNIP3/LC3B/PUMA途徑調控粒線體自噬和細胞凋亡，顯著減少了PM+I/R所引起的心臟損傷，揭示ADSC-Exo在緩解PM加重心肌I/R損傷中的潛在治療價值。

Studies in epidemiology have highlighted a significant link between exposure to fine particulate matter (PM) and an increased risk of cardiovascular disease. However, whether PM exacerbates myocardial ischemia/reperfusion (I/R) injury remains unclear, and the specific mechanisms involved in this process have not yet been fully elucidated. Our previous study has shown that adipose stem cell-derived exosomes (ADSC-Exo) contain high levels of miR-221/222. This study investigated the effects of PM exacerbates mitochondrial dysfunction and increases the processes of mitophagy and cell apoptosis in I/R settings, while demonstrating that miR-221/222 in ADSC-Exo may help alleviate these detrimental effects. Wild-type, miR-221/222 knockout (KO), and miR-221/222 overexpressing transgenic (TG) mice were administered 10 mg/kg PM through intratracheal injection. After 24 h, the mice underwent left coronary artery ligation for 30 min, followed by 3 h of reperfusion to model I/R injury. We also established an H9c2 cell model under PM (50 µg/mL) and 1% O2 for 6 h, then reoxygenated for 12 h (hypoxia-reoxygenation, H/R). PM exposure exacerbated cardiac injury induced by I/R or H/R by elevating reactive oxygen species (ROS) levels and disrupting mitochondrial function. This dysfunction was associated with an upregulation of mitochondrial fission proteins (Drp1 and MFF) and mitophagy-related proteins (BNIP3 and LC3B), both in in vivo and in vitro experimental models. Administration of ADSC-Exo or miR-221/222 mimics significantly alleviated cardiac injury induced by PM and I/R. Notably, ADSC-Exo, which are enriched with miR-221/222, directly target and suppress the expression of mitophagy and apoptosis regulators such as BNIP3, LC3B, and PUMA. This suppression reduces excessive mitophagy and apoptosis, thereby mitigating cardiac injury. The present data showed that ADSC-Exo treatment regulated mitophagy and cell apoptosis through the miR-221/222/BNIP3/LC3B/PUMA pathway and significantly reduced the cardiac damage by PM+I/R. The present study revealed the novel therapeutic potential of ADSC-Exo in alleviating PM-induced exacerbation of myocardial I/R injury.