Mycobacterium indicus pranii Supernatant Induces Apoptotic Cell Death in Mouse Peritoneal Macrophages In Vitro

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.

Cytotoxic and apoptotic effects of heat killed Mycobacterium indicus pranii (MIP) on various human cancer cell lines

“…Experimental results imply MIP HKB selectivity in MDA-MB-231, MCF-7, CaSki, A549, SK-LU-1, DU-145, HepG2, ORL-48, ORL-115 and ORL-136 with IC 50 values between 5.6 to 21 μl/(1.0 × 10 6 MIP cells/ml), all of which are lower than non-cancerous cells. According to a previous study on apoptotic cell death in in vitro by Pandey et al , 2011 15 , 60–70 μl of MIP is required to induce cell death in 40–45% mouse peritoneal macrophages while in this study, 60–70 μl/(1.0 × 10 6 MIP cells/ml) of MIP HKB induced 75% cell death. This clearly shows a tremendous reduction in MIP dose when a 60 °C heat kill technique was applied compared to autoclave heat kill technique.…”

“…In cancer treatment, MIP is used as an adjuvant to radiation therapy in patients with bladder cancer 12 and to chemotherapy plus radiotherapy in non-small cell lung cancers 10 . Four types of fractions can be obtained from MIP: LB, HKB, CS and HKS, with the most widely used fractions being the HKB fraction 13 14 and CS fraction 15 . While past studies have cited autoclaving for 20 mins at 15 lb/in 2 as the most common heat killing method, this method may denature important and biologically active proteins, which led us to heat-kill MIP at 60 °C, which was also found to be sufficient in killing MIP cultures.…”

Protein kinase C-delta (PKCδ), a marker of inflammation and tuberculosis disease progression in humans, is important for optimal macrophage killing effector functions and survival in mice

“…47 However, inhibition of PKCd with rottlerin abrogated apoptosis in murine macrophages when cultured with cell-free supernatant of Mycobacterium indicus pranni (Mw). 48 In contrast, we observed increased apoptosis in PKCd À / À macrophages following Mtb infection. This observation strengthens accumulating evidence regarding the nonspecific actions of rottlerin as a PKCd inhibitor.…”

Inactivation of nuclear factor κB by MIP-based drug combinations augments cell death of breast cancer cells

“…Previous study has demonstrated that MIP could induce mitochondria-mediated apoptosis in mouse peritoneal macrophages in vitro. 28 Thus, in this study we have tested intrinsic apoptotic protein expression in MIP combinations using Apaf-1 and caspase-9 to validate intrinsic apoptosis-mediated cell death. As shown in Figure 2 , caspase-9 cleavage products were observed in increasing concentrations, while procaspase-9 was reduced upon treatment with the two drugs and agent combinations at 6 hours in MCF-7.…”