Bone marrow-derived macrophages from BALB/c and C57BL/6 mice fundamentally differ in their respiratory chain complex proteins, lysosomal enzymes and components of antioxidant stress systems.
Macrophages are essential components of the innate immune system and crucial for pathogen elimination in early stages of infection. We previously observed that bone marrow-derived macrophages (BMMs) from C57BL/6 mice exhibited increased killing activity against Burkholderia pseudomallei compared to BMMs from BALB/c mice. This effect was particularly pronounced when cells were treated with IFN-γ. To unravel mechanisms that could explain these distinct bactericidal effects, a comparative combined proteome and transcriptome analysis of untreated and IFN-γ treated BALB/c and C57BL/6 BMMs under standardized serum-free conditions was carried out. We found differences in gene expression/protein abundance belonging to cellular oxidative and antioxidative stress systems. Genes/proteins involved in the generation of oxidant molecules and the function of phagosomes (respiratory chain ATPase, lysosomal enzymes, cathepsins) were predominantly higher expressed/more abundant in C57BL/6 BMMs. Components involved in alleviation of oxidative stress (peroxiredoxin, mitochondrial superoxide dismutase) were more abundant in C57BL/6 BMMs as well. Thus, C57BL/6 BMMs seemed to be better equipped with cellular systems that may be advantageous in combating engulfed pathogens. Simultaneously, C57BL/6 BMMs were well protected from oxidative burst. We assume that these variations co-determine differences in resistance between BALB/c and C57BL/6 mice observed in many infection models.


CONCLUSIONS
In this study we performed combined transcriptome and proteome analyses on BMMs derived from two inbred mouse strains that are frequently used for studies in the field of host-pathogen interaction research. Strain differences between BALB/c and C57BL/6 BMMs were found to originate mainly from different protein abundance levels rather than from different gene expression. Differences in abundance of respiratory chain complexes and lysosomal proteins as well as differential regulation of components belonging to various antioxidant stress systems help to explain long-known differences between the mouse strains concerning their different susceptibility in several infection models.
ZIK-FunGene Junior Research Group "Applied Proteomics", Interfaculty Institute for Genetics and Functional Genomics, Department of Functional Genomics, University Medicine Greifswald, Greifswald, Germany; Interfaculty Institute for Genetics and Functional Genomics, Department of Functional Genomics, University Medicine Greifswald, Greifswald, Germany.
Maren
M
Depke
Friedrich Loeffler Institute for Medical Microbiology, University Medicine Greifswald, Greifswald, Germany.
Katrin
K
Breitbach
Interfaculty Institute for Genetics and Functional Genomics, Department of Functional Genomics, University Medicine Greifswald, Greifswald, Germany.
Khoa
K
Dinh Hoang Dang
Interfaculty Institute for Genetics and Functional Genomics, Department of Functional Genomics, University Medicine Greifswald, Greifswald, Germany.
Lars
L
Brinkmann
ZIK-FunGene Junior Research Group "Applied Proteomics", Interfaculty Institute for Genetics and Functional Genomics, Department of Functional Genomics, University Medicine Greifswald, Greifswald, Germany; Interfaculty Institute for Genetics and Functional Genomics, Department of Functional Genomics, University Medicine Greifswald, Greifswald, Germany.
Manuela Gesell
MG
Salazar
Interfaculty Institute for Genetics and Functional Genomics, Department of Functional Genomics, University Medicine Greifswald, Greifswald, Germany.
Vishnu Mukund
VM
Dhople
Friedrich Loeffler Institute for Medical Microbiology, University Medicine Greifswald, Greifswald, Germany.
Antje
A
Bast
Interfaculty Institute for Genetics and Functional Genomics, Department of Functional Genomics, University Medicine Greifswald, Greifswald, Germany.
Leif
L
Steil
ZIK-FunGene Junior Research Group "Applied Proteomics", Interfaculty Institute for Genetics and Functional Genomics, Department of Functional Genomics, University Medicine Greifswald, Greifswald, Germany.
Frank
F
Schmidt
Friedrich Loeffler Institute for Medical Microbiology, University Medicine Greifswald, Greifswald, Germany.
Ivo
I
Steinmetz
Interfaculty Institute for Genetics and Functional Genomics, Department of Functional Genomics, University Medicine Greifswald, Greifswald, Germany. Electronic address: voelker@uni-greifswald.de.
Uwe
U
Völker
D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001854:Bone Marrow Cells / Q000187:drug effects / Q000378:metabolism; D016957:Burkholderia pseudomallei / Q000187:drug effects; D004579:Electron Transport; D007371:Interferon-gamma / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D020543:Proteome; D059467:Transcriptome
D000975:Antioxidants; D020543:Proteome; D007371:Interferon-gamma
BALB/c; C57BL/6; IFN-γ; Macrophages; Proteome; Transcriptome