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Detection of Inflammasome Activation and Pyroptotic Cell Death in Murine Bone Marrow-derived Macrophages
Published on: May 21, 2018
Mycobacterium indicus pranii supernatant induces apoptotic cell death in mouse peritoneal macrophages in vitro
Rajeev Kumar Pandey1, Kunal H Bhatt, Yogesh Dahiya
1School of Biotechnology, Faculty of Science, Banaras Hindu University, Varanasi, India.
Abstract:
Mycobacterium indicus pranii (MIP), also known as Mw, is a saprophytic, non-pathogenic strain of Mycobacterium and is commercially available as a heat-killed vaccine for leprosy and recently tuberculosis (TB) as part of MDT. In this study we provide evidence that cell-free supernatant collected from original MIP suspension induces rapid and enhanced apoptosis in mouse peritoneal macrophages in vitro. It is demonstrated that the MIP cell-free supernatant induced apoptosis is mitochondria-mediated and caspase independent and involves mitochondrial translocation of Bax and subsequent release of AIF and cytochrome c from the mitochondria. Experiments with pharmacological inhibitors suggest a possible role of PKC in mitochondria-mediated apoptosis of macrophages.
Insights
Heat-killed Mycobacterium indicus pranii (MIP) supernatant triggers rapid macrophage apoptosis. This caspase-independent, mitochondria-mediated cell death involves Bax translocation and AIF/cytochrome c release, potentially regulated by PKC.
Area of Science:
- Immunology
- Cell Biology
- Microbiology
Background:
- Mycobacterium indicus pranii (MIP) is a non-pathogenic Mycobacterium strain used in vaccines for leprosy and tuberculosis (TB).
- Understanding the immunomodulatory effects of MIP components is crucial for vaccine development and therapeutic strategies.
Purpose of the Study:
- To investigate the in vitro effects of cell-free supernatant from MIP on mouse peritoneal macrophages.
- To elucidate the mechanism of MIP-induced apoptosis in macrophages.
Main Methods:
- Primary mouse peritoneal macrophages were treated with cell-free MIP supernatant.
- Apoptosis was assessed using various assays.
- Mitochondrial membrane potential, Bax translocation, and release of apoptosis-inducing factor (AIF) and cytochrome c were analyzed.
- Pharmacological inhibitors were used to explore signaling pathways.
Main Results:
- MIP cell-free supernatant induced rapid and enhanced apoptosis in mouse peritoneal macrophages.
- The observed apoptosis was mitochondria-mediated and caspase-independent.
- Mitochondrial translocation of Bax and subsequent release of AIF and cytochrome c were key events.
- Protein kinase C (PKC) inhibition suggested a potential role in the apoptotic pathway.
Conclusions:
- MIP cell-free supernatant effectively induces apoptosis in macrophages via a mitochondria-dependent, caspase-independent pathway.
- Bax translocation and release of mitochondrial factors (AIF, cytochrome c) are critical.
- PKC may play a regulatory role in MIP-induced macrophage apoptosis.
