Exposure to particulate matter induces cardiomyocytes apoptosis after myocardial infarction through NFκB activation

Area of Science:

• Environmental Health
• Cardiovascular Biology
• Toxicology

Background:

• Clinical studies link air pollution (PM2.5) to increased heart attack (myocardial infarction) mortality.
• The precise mechanisms by which PM2.5 exacerbates myocardial infarction are not fully understood.

Purpose of the Study:

• To investigate the detrimental effects of PM2.5 exposure on heart muscle (myocardium) following myocardial infarction.
• To elucidate the underlying molecular mechanisms involved in PM2.5-induced cardiac damage.

Main Methods:

• Mice with induced myocardial infarction were exposed to PM2.5 via intranasal instillation.
• Neonatal mouse ventricular myocytes (NMVMs) were subjected to hypoxia and treated with PM2.5 in vitro.
• Cellular apoptosis was assessed using TUNEL assays, flow cytometry, and Western blotting for apoptosis markers (Caspase-3, Bax, Bcl-2).
• The NF-κB pathway activation and inflammatory cytokine gene expression (IL-1β, IL-6) were analyzed, with NF-κB translocation blockade using SN-50.

Main Results:

• PM2.5 exposure significantly worsened cardiac function and increased infarct size in mice with myocardial infarction.
• PM2.5 induced significant cellular apoptosis in both in vivo and in vitro models.
• PM2.5 activated the NF-κB pathway and upregulated IL-1β and IL-6 gene expression in hypoxic NMVMs.
• NF-κB pathway blockade reversed the PM2.5-induced effects on gene expression.

Conclusions:

• PM2.5 exposure promotes myocardial apoptosis, leading to impaired cardiac function and aggravated myocardial infarction.
• The NF-κB signaling pathway plays a critical role in mediating the adverse cardiac effects of PM2.5.
• Findings highlight air pollution as a significant risk factor for cardiovascular events and suggest therapeutic targets within the NF-κB pathway.