z‐VAD‐FMK triggers macrophage necroptosis during mycobacterial infection via a non‐canonical off‐target mechanism
7 affiliations
- 1Department of Immunology and Microbiology, School of Life Sciences Southern University of Science and Technology Shenzhen China
- 2Shenzhen Third People's Hospital The Second Affiliated Hospital of Southern University of Science and Technology Shenzhen China
- 3Department of Microbiology and Immunology Weill Cornell Medicine New York New York USA
- 4Department of Immunology University of Pittsburgh School of Medicine Pittsburgh Pennsylvania USA
- 5Tumor Microenvironment Center, UPMC Hillman Cancer Center University of Pittsburgh Pittsburgh Pennsylvania USA
- 6Cancer Immunology and Immunotherapy Program UPMC Hillman Cancer Center Pittsburgh Pennsylvania USA
- 7National Clinical Research Center for Infectious Diseases (SHENZHEN) Shenzhen China
Abstract
Macrophages are the predominant cell type infected by Mycobacterium tuberculosis (Mtb) in tuberculosis (TB). Death of Mtb‐infected macrophages promotes tissue pathology and releases Mtb to infect other cells, suggesting that inhibiting the death of Mtb‐infected macrophages could be an adjunctive treatment of TB. Prospects for such an intervention depend on identifying the molecular pathways leading to cell death. We previously reported that the death of Mtb‐infected mouse macrophages in vitro depends on type I interferons (IFNs) and lysosomal membrane permeabilization contributes to cell death. Here, we report that the death of Mtb‐infected primary mouse macrophages in vitro became necroptotic in the presence of a pan‐caspase inhibitor, benzyloxycarbonyl‐Val‐Ala‐Asp‐fluoromethylketone (z‐VAD‐FMK, hereafter called z‐VAD) acting on a target other than caspase‐8. Macrophages infected with Mycobacterium kansasii or Rhodococcus equi likewise underwent z‐VAD‐dependent necroptosis. In TB‐resistant C57BL/6 mice, the deficiency of the key necroptosis executioner, mixed lineage kinase domain‐like (MLKL), did not affect bacterial burden or pulmonary pathology. In contrast, in mice lacking the IFN repressor SP140, which express high levels of type I IFNs after Mtb infection and develop necrotic pulmonary lesions, MLKL‐deficiency reduced bacterial burden and pathology after high‐dose infection. This report illustrates that off‐target action(s) of a caspase‐8 inhibitor can switch the cell death pathway to necroptosis in macrophages infected with several Gram‐positive pathogens and highlights that necroptosis can exacerbate TB. Identifying the target of z‐VAD may help to delineate how necrotic lesions form in TB.
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BibTeX
@article{hu2026zvadfmk,
title = {{z‐VAD‐FMK triggers macrophage necroptosis during mycobacterial infection via a non‐canonical off‐target mechanism}},
author = {Rong Hu and Pei Li and Jie Han and Jiamin Huang and Guoyi Huang and Xiuju Jiang and Daniel Pfau and Guobao Li and Yi‐Nan Gong and Carl F. Nathan and Li Zhang},
journal = {mLife},
year = {2026},
month = oct,
doi = {10.1002/mlf2.70101},
url = {https://doi.org/10.1002/mlf2.70101},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - z‐VAD‐FMK triggers macrophage necroptosis during mycobacterial infection via a non‐canonical off‐target mechanism
AU - Rong Hu
AU - Pei Li
AU - Jie Han
AU - Jiamin Huang
AU - Guoyi Huang
AU - Xiuju Jiang
AU - Daniel Pfau
AU - Guobao Li
AU - Yi‐Nan Gong
AU - Carl F. Nathan
AU - Li Zhang
PY - 2026
DA - 2026/10/01
JO - mLife
DO - 10.1002/mlf2.70101
UR - https://doi.org/10.1002/mlf2.70101
AB - Macrophages are the predominant cell type infected by Mycobacterium tuberculosis (Mtb) in tuberculosis (TB). Death of Mtb‐infected macrophages promotes tissue pathology and releases Mtb to infect other cells, suggesting that inhibiting the death of Mtb‐infected macrophages could be an adjunctive treatment of TB. Prospects for such an intervention depend on identifying the molecular pathways leading to cell death. We previously reported that the death of Mtb‐infected mouse macrophages in vitro depends on type I interferons (IFNs) and lysosomal membrane permeabilization contributes to cell death. Here, we report that the death of Mtb‐infected primary mouse macrophages in vitro became necroptotic in the presence of a pan‐caspase inhibitor, benzyloxycarbonyl‐Val‐Ala‐Asp‐fluoromethylketone (z‐VAD‐FMK, hereafter called z‐VAD) acting on a target other than caspase‐8. Macrophages infected with Mycobacterium kansasii or Rhodococcus equi likewise underwent z‐VAD‐dependent necroptosis. In TB‐resistant C57BL/6 mice, the deficiency of the key necroptosis executioner, mixed lineage kinase domain‐like (MLKL), did not affect bacterial burden or pulmonary pathology. In contrast, in mice lacking the IFN repressor SP140, which express high levels of type I IFNs after Mtb infection and develop necrotic pulmonary lesions, MLKL‐deficiency reduced bacterial burden and pathology after high‐dose infection. This report illustrates that off‐target action(s) of a caspase‐8 inhibitor can switch the cell death pathway to necroptosis in macrophages infected with several Gram‐positive pathogens and highlights that necroptosis can exacerbate TB. Identifying the target of z‐VAD may help to delineate how necrotic lesions form in TB.
SN - 2097-1699
SN - 2770-100X
ER -