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Updated: May 24, 2026
Quantification of Cytosolic vs. Vacuolar Salmonella in Primary Macrophages by Differential Permeabilization
Published on: July 28, 2015
Copper redistribution in murine macrophages in response to Salmonella infection
Maud E S Achard1, Sian L Stafford, Nilesh J Bokil
1School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, Brisbane, Australia.
Abstract:
The movement of key transition metal ions is recognized to be of critical importance in the interaction between macrophages and intracellular pathogens. The present study investigated the role of copper in mouse macrophage responses to Salmonella enterica sv. Typhimurium. The copper chelator BCS (bathocuproinedisulfonic acid, disodium salt) increased intracellular survival of S. Typhimurium within primary mouse BMM (bone-marrow-derived macrophages) at 24 h post-infection, implying that copper contributed to effective host defence against this pathogen. Infection of BMM with S. Typhimurium or treatment with the TLR (Toll-like receptor) 4 ligand LPS (lipopolysaccharide) induced the expression of several genes encoding proteins involved in copper transport [Ctr (copper transporter) 1, Ctr2 and Atp7a (copper-transporting ATPase 1)], as well as the multi-copper oxidase Cp (caeruloplasmin). Both LPS and infection with S. Typhimurium triggered copper accumulation within punctate intracellular vesicles (copper 'hot spots') in BMM as indicated by the fluorescent reporter CS1 (copper sensor 1). These copper hot spots peaked in their accumulation at approximately 18 h post-stimulation and were dependent on copper uptake into cells. Localization studies indicated that the copper hot spots were in discrete vesicles distinct from Salmonella containing vacuoles and lysosomes. We propose that copper hot spot formation contributes to antimicrobial responses against professional intracellular bacterial pathogens.
Insights
Copper accumulation in macrophages is crucial for fighting Salmonella Typhimurium infection. Depleting copper enhances pathogen survival, highlighting copper
Area of Science:
- Immunology
- Microbiology
- Cell Biology
Background:
- Transition metal ion movement is vital for macrophage interactions with intracellular pathogens.
- Copper's role in macrophage defense against Salmonella Typhimurium was investigated.
Purpose of the Study:
- To elucidate the function of copper in mouse macrophage responses to Salmonella Typhimurium.
- To understand copper's contribution to host defense mechanisms.
Main Methods:
- Utilized copper chelator BCS to assess copper's impact on S. Typhimurium survival in bone-marrow-derived macrophages (BMM).
- Analyzed gene expression of copper transport proteins (Ctr1, Ctr2, Atp7a) and caeruloplasmin (Cp) upon infection or LPS stimulation.
- Employed copper sensor 1 (CS1) to visualize and quantify intracellular copper accumulation in BMM.
Main Results:
- Chelation of copper with BCS increased intracellular S. Typhimurium survival in BMM.
- S. Typhimurium infection and LPS treatment upregulated copper transport and Cp gene expression.
- Copper accumulated in intracellular vesicles ('hot spots') within BMM, distinct from pathogen-containing vacuoles and lysosomes.
Conclusions:
- Copper plays a significant role in the innate immune response of macrophages against Salmonella Typhimurium.
- Copper accumulation in specific intracellular vesicles ('hot spots') is a key component of the antimicrobial defense mechanism.
- Targeting copper homeostasis may offer novel therapeutic strategies against intracellular bacterial pathogens.
