Mycobacterium kansasii-induced death of murine macrophages involves endoplasmic reticulum stress responses mediated by reactive oxygen species generation or calpain activation

Abstract

Although pathogenic mechanisms of tuberculosis have been extensively studied, little is known about the pathogenic mechanisms of Mycobacterium kansasii. In this work the influence of virulence and ER-stress mediated apoptosis of macrophages during two different strains of M. kansasii infection was investigated. We show that M. kansasii infection is associated with ER stress-mediated apoptosis in the murine macrophage cell line RAW 264.7. Infection of RAW 264.7 cells in vitro with apoptosis-inducing a clinical isolate of M. kansasii SM-1 (SM-1) resulted in strong induction of ER stress responses compared with M. kansasii type strain (ATCC 12478)-infected RAW 264.7 cells. Interestingly, inhibition of calpain prevented the induction of CHOP and Bip in ATCC 12478-infected RAW 264.7 cells but not in RAW 264.7 cells infected with SM-1. In contrast, reactive oxygen species (ROS) were significantly increased only in RAW 264.7 cells infected with SM-1. We propose that ROS generation is important for triggering ER stress-mediated apoptosis during SM-1 infection, whereas ATCC 12478-induced, ER stress-mediated apoptosis is associated with calpain activation. Our results demonstrate that the ER stress pathway plays important roles in the pathogenesis of M. kansasii infections, and that different strains of M. kansasii induce different patterns of ER stress-mediated apoptosis.

Roles of endoplasmic reticulum stress-mediated apoptosis in M1-polarized macrophages during mycobacterial infections

“…Previously, we suggested that ER stress-mediated apoptosis is important for the regulation of intracellular survival of mycobacteria151821. We noted here that the ER stress response is increased in M1 macrophages after Mtb infection.…”

“…In our previous reports, we suggested that ER stress-mediated apoptosis plays an important role in the regulation of mycobacterial infection1821. We next determined whether virulent mycobacteria could modulate macrophage polarization to control ER stress.…”

“…Mtb used in this experiment were prepared in vitro as described previously1821. Heat-killed mycobacteria were prepared by incubating H37Rv and H37Ra suspensions at 80 °C for 30 min, and stored at −80 °C.…”

Mycobacterium avium MAV2054 protein induces macrophage apoptosis by targeting mitochondria and reduces intracellular bacterial growth

“…It is well-known that ROS can induce apoptosis and pro-inflammatory cytokine production in macrophages3334. To examine the involvement of ROS generation on the effects of MAV2054 in RAW264.7 cells, the oxidation of 2′,7′-dichlorodihydrofluorescein diacetate (H2DCFDA) was assessed by flow cytometry.…”

A Mycobacterial Phosphoribosyltransferase Promotes Bacillary Survival by Inhibiting Oxidative Stress and Autophagy Pathways in Macrophages and Zebrafish

“…ROS plays a crucial role in the control of mycobacterial growth in macrophages (95,96). Pathogenic mycobacteria suppress free radical production to subvert macrophage control of intracellular bacilli load.…”