Siderophores induce mitophagy-dependent apoptosis in platelets

Area of Science:

• Platelet biology and pathobiology
• Microbial pathogenesis and host-pathogen interactions
• Cellular signaling and programmed cell death

Background:

• Siderophores from *K. pneumoniae* are virulence factors that chelate iron.
• Iron chelation can induce mitochondrial dysfunction, reactive oxygen species (ROS), mitophagy, and apoptosis.
• The specific effects of siderophores on platelets remain largely unexplored.

Purpose of the Study:

• To investigate the impact of *K. pneumoniae* siderophores on platelet mitophagy and apoptosis.
• To elucidate the molecular mechanisms underlying siderophore-induced platelet responses.

Main Methods:

• *In vitro* treatment of human platelets with various siderophores.
• Western blot analysis of mitophagy and apoptosis-related proteins (TOMM20, TIMM23, LC3, p62, PINK1/Parkin, BNIP3, caspase3).
• Immunofluorescence assays for mitotracker and LC3-II co-localization.
• Flow cytometry to assess reactive oxygen species (ROS) levels.

Main Results:

• Siderophores increased LC3-II expression and decreased mitochondrial proteins (TOMM20, TIMM23).
• Enterobactin treatment enhanced mitotracker and LC3-II co-localization, indicating mitophagy.
• All tested siderophores elevated ROS levels and activated mitophagy via PINK1/Parkin and BNIP3 pathways.
• Siderophore treatment increased caspase3 expression, which was reduced upon mitophagy pathway inhibition.

Conclusions:

• *K. pneumoniae* siderophores induce mitophagy in platelets.
• Platelet mitophagy subsequently triggers apoptosis.
• This siderophore-induced platelet apoptosis presents a potential therapeutic target for infection-related thrombocytopenia.