bims-inflin 2025-03-16 papers

Elife. 2025 Mar 13. pii: RP102980. [Epub ahead of print]13

Impaired fatty acid import or catabolism in macrophages restricts intracellular growth of Mycobacterium tuberculosis.

Nelson V Simwela, Eleni Jaecklein, Christopher M Sassetti, David G Russell.

Mycobacterium tuberculosis (Mtb) infection of macrophages reprograms cellular metabolism to promote lipid retention. While it is clearly known that intracellular Mtb utilize host-derived lipids to maintain infection, the role of macrophage lipid processing on the bacteria's ability to access the intracellular lipid pool remains undefined. We utilized a CRISPR-Cas9 genetic approach to assess the impact of sequential steps in fatty acid metabolism on the growth of intracellular Mtb. Our analyses demonstrate that macrophages that cannot either import, store, or catabolize fatty acids restrict Mtb growth by both common and divergent antimicrobial mechanisms, including increased glycolysis, increased oxidative stress, production of pro-inflammatory cytokines, enhanced autophagy, and nutrient limitation. We also show that impaired macrophage lipid droplet biogenesis is restrictive to Mtb replication, but increased induction of the same fails to rescue Mtb growth. Our work expands our understanding of how host fatty acid homeostasis impacts Mtb growth in the macrophage.

Keywords: infectious disease; lipid metabolism; macrophage; microbiology; mouse; mycobacterium; tuberculosis

DOI: https://doi.org/10.7554/eLife.102980

Cell Host Microbe. 2025 Mar 12. pii: S1931-3128(25)00061-7. [Epub ahead of print]33(3): 322-324

It takes three: A cocktail of protists, bacterial sphingolipids and an inflammasome.

Michael E Grigg, Eliza V C Alves-Ferreira.

Symbiotic relationships between mammalian hosts and their flora impact host immunity and disease. In this issue, Winsor and colleagues define a trans-kingdom interaction, which protects against colorectal cancer. Tritrichomonas protists initiate a Bacteroides bloom and sphingolipid release, which activates the NLRP6 inflammasome, enhancing protective mucus secretion by sentinel goblet cells.

DOI: https://doi.org/10.1016/j.chom.2025.02.013

Proc Natl Acad Sci U S A. 2025 Mar 11. 122(10): e2404899122

Dynamic investigation of hypoxia-induced L-lactylation.

Jinjun Gao, Ruilong Liu, Kevin Huang, Ziyuan Li, Xinlei Sheng, Kasturi Chakraborty, Chang Han, Di Zhang, Lev Becker, Yingming Zhao.

The recently identified histone modification lysine lactylation can be stimulated by L-lactate and glycolysis. Although the chemical group added upon lysine lactylation was originally proposed to be the L-enantiomer of lactate (KL-la), two isomeric modifications, lysine D-lactylation (KD-la) and N-ε-(carboxyethyl) lysine (Kce), also exist in cells, with their precursors being metabolites of glycolysis. The dynamic regulation and differences among these three modifications in response to hypoxia remain poorly understood. In this study, we demonstrate that intracellular KL-la, but not KD-la or Kce, is up-regulated in response to hypoxia. Depletion of glyoxalase enzymes, GLO1 and GLO2, had minimal impact on KD-la, Kce, or hypoxia-induced KL-la. Conversely, blocking glycolytic flux to L-lactate under hypoxic conditions by knocking out lactate dehydrogenase A/B completely abolished the induction of KL-la but increased KD-la and Kce. We further observed a correlation between the level of KL-la and hypoxia-inducible factor 1 alpha (HIF-1α) expression under hypoxic conditions and when small molecules were used to stabilize HIF-1α in the normoxia condition. Our result demonstrated that there is a strong correlation between HIF-1α and KL-la in lung cancer tissues and that patient samples with higher grade tend to have higher KL-la levels. Using a proteomics approach, we quantified 66 KL-la sites that were up-regulated by hypoxia and demonstrated that p300/CBP contributes to hypoxia-induced KL-la. Collectively, our study demonstrates that KL-la, rather than KD-la or Kce, is the prevailing lysine lactylation in response to hypoxia. Our results therefore demonstrate a link between KL-la and the hypoxia-induced adaptation of tumor cells.

Keywords: LC–MS/MS; hypoxia; lactylation; posttranslational modification (PTM)

DOI: https://doi.org/10.1073/pnas.2404899122

FEBS J. 2025 Mar 12.

Caspase-1/11 controls Zika virus replication in astrocytes by inhibiting glycolytic metabolism.

Ingrid S de Farias, Guilherme Ribeiro, Isaú H Noronha, Victoria Weise L Lucena, Jean P S Peron, Pedro M Moraes-Vieira, Jose C Alves-Filho, Karina R Bortoluci.

Zika virus (ZIKV) poses a significant threat due to its association with severe neurological complications, particularly during pregnancy. Although viruses exhibit tropism for neural cells, including astrocytes, the role of these cells in controlling ZIKV replication remains unclear. In this study, we demonstrated that ZIKV induces caspase-1 activation in primary astrocytes despite the absence of classical signs of inflammasome activation. Caspase-1 and caspase-11 double knockout (caspase-1/11-/-) astrocytes exhibit heightened permissiveness to viral replication, accompanied by overactivation of glycolytic metabolism. Inhibition of glycolysis reversed the susceptibility of caspase-1/11-/- astrocytes to ZIKV infection. Protein network analysis revealed mammalian target of rapamycin complex (mTORC) as a link between proteins involved in glycolysis and caspase-1, and mTORC inhibition also suppressed viral replication. Furthermore, we found that the impact of caspase-1/11 on astrocytes depends on the regulation of pyruvate transport to mitochondria for viral replication. Overall, our findings elucidate a caspase-1/11-dependent microbicidal mechanism in astrocytes that involves the mTORC/glycolytic pathway/pyruvate axis, providing insights into potential therapeutic targets for ZIKV infection.

Keywords: Zika virus; astrocytes; caspase‐1/11; glycolysis; pyruvate

DOI: https://doi.org/10.1111/febs.70061

mBio. 2025 Mar 12. e0252424

SENP1-SIRT3 axis mediates glycolytic reprogramming to suppress inflammation during Listeria monocytogenes infection.

Yan Xiong, Yongliang Du, Feng Lin, Beibei Fu, Dong Guo, Zhou Sha, Rong Tian, Rui Yao, Lulu Wang, Zixuan Cong, Bohao Li, Xiaoyuan Lin, Haibo Wu.

Listeria monocytogenes, a foodborne pathogen, has the ability to invade intestinal mucosal cells, undergo intracellular proliferation, activate host immune responses, and induce diseases such as colitis. We have demonstrated that sentrin-specific protease 1 (SENP1) functions as a protective gene in the host, suppressing the inflammatory response triggered by Listeria monocytogenes. The host's SENP1-SIRT3 axis plays a critical role in regulating inflammation during Listeria monocytogenes infection. Our findings reveal that overexpression of SENP1, particularly under Listeria monocytogenes infection conditions (MOI = 20), effectively suppresses inflammation through modulation of glycolysis. Mechanistically, during Listeria monocytogenes infection, SENP1 accumulates in the mitochondria, facilitating the de-SUMOylation and activation of sirtuin 3 (SIRT3). Activated SIRT3 then regulates the deacetylation of pyruvate kinase M2 (PKM2), leading to a decrease in glycolytic intermediates, downregulation of glycolysis-related gene expression, and suppression of inflammation. Taken together, our study provides a deeper understanding of the mechanistic role of the SENP1-SIRT3 axis in the regulation of inflammation, offering novel insights, and strategies for the treatment and prevention of inflammatory diseases.
IMPORTANCE: Sentrin-specific protease 1 (SENP1)-sirtuin 3 (SIRT3) has never been reported in the regulation of bacteria-induced inflammation. Our study demonstrated that SENP1 acted as a protective factor against Listeria-induced inflammation by promoting SIRT3 activation and subsequent metabolic reprogramming. The SENP1-SIRT3 axis served not only as an essential signaling pathway for regulating mitochondrial metabolic responses to metabolic stress but also responds to bacterial invasion and plays a protective role in the organism. Our findings provide a basis for further research into targeting the SENP1-SIRT3 signaling pathway for the treatment of bacterial infections.

Keywords: Listeria monocytogenes; PKM2; SENP1-SIRT3 axis; SUMO; glycolysis

DOI: https://doi.org/10.1128/mbio.02524-24

Methods Cell Biol. 2025 ;pii: S0091-679X(24)00016-5. [Epub ahead of print]194 19-42

Visualizing mitochondrial electron transport chain complexes and super-complexes during infection of human macrophages with Legionella pneumophila.

Mariatou Dramé, Daniel Schator, Carmen Buchrieser, Pedro Escoll.

The ultrastructure of mitochondria is pivotal for their respiratory activity. Thus, the regulation of the assembly of the super-complexes (SCs) of the mitochondrial electron transport chain (ETC) might be a core aspect of macrophage immunometabolism during bacterial infection. In order to study the impact of infection by Legionella pneumophila on the configuration of mitochondrial complexes and SCs in human macrophages, we have adapted and combined different methods such as cell sorting of infected cells, magnetic isolation of highly pure and functional mitochondria, quality control of mitochondrial purity by flow cytometry, and BN-PAGE (Blue-Native Polyacrylamide Gel Electrophoresis) coupled to Western Blot using near-infrared (NIR) fluorescence. The here presented protocol uses infected and non-infected human macrophage-like THP-1 cells and GFP-expressing L. pneumophila, but the method can be used to analyze the configuration of ETC complexes and SCs also in other mammalian cells and infected with different intracellular bacteria expressing a fluorescent protein.

Keywords: Blue-native PAGE; Electron transport chain; Human macrophages; Legionella pneumophila; Mitochondria; Mitochondria isolation; OXPHOS; Super-complexes; THP-1

DOI: https://doi.org/10.1016/bs.mcb.2024.01.003