Copper in Infectious Disease: Using both sides of the penny

Clincal Overview

This narrative review examines copper (Cu) as both an essential micronutrient and a potent antimicrobial at the host–pathogen interface, with emphasis on fungal pathogens (Cryptococcus neoformans, Aspergillus fumigatus, Candida albicans), bacteria, viruses (including coronaviruses), and mammalian immune and parenchymal cells. Cu exists primarily as Cu(I) and Cu(II), enabling redox chemistry but also driving toxicity via Fenton-like reactions, Fe–S cluster disruption, and mis-metalation of Zn sites. Macrophages exploit a Cu “burst” in phagolysosomes via CTR1 and ATP7A to combine high Cu with reactive oxygen species, whereas tissues such as lung, brain, and kidney create spatially and temporally distinct Cu landscapes that alternately poison or starve invading microbes. Fungi counter by tightly regulated Cu uptake, efflux, sequestration, and cofactor swapping in key enzymes such as Cu/Zn superoxide dismutase (SOD1), Cu-only SODs, Mn-SOD3, and Fe-dependent alternative oxidase (AOX2), with these responses proving essential for virulence in multiple mouse models.

What was reviewed and who was studied

The paper is a mechanistic, non-systematic review of Cu metabolism in infectious disease, spanning in vitro macrophage models, bacterial and fungal pathogens (notably C. neoformans, A. fumigatus, C. albicans), viral inactivation on Cu surfaces, and in vivo murine infection models focused on lung, brain, and kidney Cu redistribution and fungal virulence.

Finding	Details and context
Cu as broad-spectrum antimicrobial	Dry Cu surfaces rapidly kill bacteria, fungi and inactivate DNA/RNA viruses; SARS-CoV-2 and SARS-CoV-1 remain viable up to 72 h on plastic/steel but show no detectable live virus within 4 h on Cu alloys.
Macrophage Cu burst	Activated macrophages upregulate CTR1 and ATP7A, rerouting Cu to phagolysosomes where high Cu plus ROS drive Fenton chemistry and mis-metalation of microbial enzymes; Cu-deficient macrophages show impaired killing.
Microbial Cu detoxification	Pathogens export Cu via P-type ATPases, sequester it in metallothioneins or metallophores (e.g., yersiniabactin), and oxidize Cu(I) to Cu(II) via multicopper oxidases, enabling survival in Cu-rich macrophage and tissue niches.
Nutritional immunity for Cu in fungi	Hosts can also generate Cu-limiting microenvironments. C. neoformans faces high Cu in lung but Cu scarcity in brain; the Cuf1-regulated metallothioneins (Cmt1/Cmt2) and Cu transporters (Ctr1/Ctr4, Bim1) are required for virulence and show high expression in murine and human brain infection.
Dual Cu landscapes in lung macrophages	Phagosomal Cu rises ∼10-fold at 1 h after infection with mycobacteria before falling below baseline by 24 h; fungal pathogens such as Histoplasma and Cryptococcus show signatures of both Cu toxicity and Cu starvation within phagocytes.
Dynamic kidney Cu in candidiasis	In murine disseminated C. albicans infection, early kidney Cu is elevated, inducing Ace1-dependent CRP1 and Cu/Zn SOD1; later, kidney Cu falls, triggering Mac1-dependent CTR1, Mn-SOD3 and AOX2 with SOD1 repression. Deletion of CRP1, CTR1 or MAC1 markedly attenuates virulence.
Systemic Cu and ceruloplasmin	Infection increases serum Cu via hepatic ceruloplasmin (ATP7B-dependent), supporting recovery from anemia of inflammation by promoting Fe loading of transferrin rather than directly attacking microbes.

Implications for Microbial Metallomics

Across these models, the Cu metallome integrates redox speciation, compartmentalization, and competition between host and microbe to determine infection outcomes.

Concept	Implication
Cu(I)/Cu(II) redox cycling in phagolysosomes	Quantifying labile Cu pools and redox state in phagosomes, alongside Fe–S cluster integrity, could mechanistically link Cu-mediated oxidative damage to microbial killing efficiency.
Organ-specific Cu landscapes (lung high Cu; brain and late kidney low Cu)	Metallomic profiling must be organ- and time-resolved; the same microbe adjusts its Cu uptake and detoxification programs differently in lung, brain, and kidney, influencing virulence.
Fungal Cu-responsive transcription factors (Cuf1, Ace1, Mac1)	These regulators define pathogen metallomes under Cu excess versus Cu starvation, guiding which cuproenzymes (e.g., COX, SOD1) retain Cu; their target gene sets are natural readouts of in situ Cu stress.
Cu sparing from SOD1 to COX in C. albicans	Measuring Cu occupancy of SOD1 versus cytochrome c oxidase during infection could reveal how pathogens prioritize respiratory Cu usage under host-imposed Cu limitation.
Host ceruloplasmin-driven Cu surge and Fe re-distribution	Integrated Cu–Fe metallomics (serum, liver, marrow) may clarify how systemic Cu shifts support recovery from anemia of inflammation while indirectly shaping microbial metal access.
Cu-driven antimicrobial biomaterials	Viral and fungal susceptibility to Cu surfaces suggests that surface-associated Cu speciation and release kinetics are measurable parameters that could be optimized using metallomic tools for infection control.

Limitations

This is a narrative, not systematic, review, with a focus on select fungal models (C. neoformans, A. fumigatus, C. albicans) and specific bacterial and viral examples. Quantitative Cu concentrations and speciation in host tissues and phagosomes are rarely reported. Organ- and time-resolved Cu data derive from limited murine models, constraining generalizability across species and clinical settings.

Future perspectives

Next steps logically include precise, compartment-resolved measurement of Cu(I) and Cu(II) in phagolysosomes, lung, brain, and kidney during infection, coupled to fungal and bacterial transcriptomic Cu signatures (Ace1/Mac1/Cuf1 regulons and Cu ATPases). Studies that compare Cu flux with Fe, Zn, and Mn transporters such as Nramp1 could refine the concept of “nutritional immunity” for Cu. For translation, rigorously controlled in vivo evaluations of Cu-based surfaces and Cu-modulating interventions, benchmarked against pathogen Cu homeostasis mutants, would clarify therapeutic windows between microbial killing and host toxicity.

Key takeaways for Researchers and Clinicians

This review synthesizes how host and pathogen compete for Cu across lung, brain, kidney, and the phagolysosome, with particular detail for pathogenic fungi facing alternating Cu overload and Cu starvation. The key metal is copper, in both Cu(I) and Cu(II) forms, whose redox chemistry drives antimicrobial Fenton reactions yet is indispensable for cuproenzymes such as SOD1, Cu-only SODs, and cytochrome c oxidase. Cu biology is not just “trace nutrition”; it actively shapes virulence and host defense, making Cu handling pathways plausible targets for diagnostics, anti-infective strategies, and even infection-responsive biomaterials.

The clearest outcome associations include rapid loss of coronavirus viability on Cu surfaces, reduced microbial survival when Cu detoxification or uptake pathways are disrupted, and attenuated C. albicans virulence when either Cu export (CRP1), Cu uptake (CTR1), or the Cu starvation regulator Mac1 are deleted. Methodologically, following Cu-responsive regulons and enzyme cofactor switching (SOD1→Mn-SOD3/AOX2) provides a powerful functional readout of in vivo Cu landscapes. In translational terms, microbial metallomics of Cu offers a mechanistic bridge from atomic-level redox chemistry to organ-specific infection phenotypes and potential Cu-targeted interventions.

Citation

Culbertson EM, Culotta VC. Copper in infectious disease: Using both sides of the penny. Seminars in Cell and Developmental Biology. doi:10.1016/j.semcdb.2020.12.003