Intracellular survival of Staphylococcus aureus: correlating production of catalase and superoxide dismutase with levels of inflammatory cytokines.
BACKGROUND
Superoxide dismutase (SOD) and catalase are anti-oxidant enzymes potentially used by the bacteria to neutralize macrophage microbicidal molecules such as hydrogen peroxide (H2O2).


OBJECTIVE
To investigate contribution of bacterial anti-oxidant enzymes in intracellular survival of Staphylococcus aureus (S. aureus) within macrophages.


METHODS
Murine peritoneal macrophages and S. aureus (CMC-524, ICH-629 and ICH-757).


METHODS
10(6) colony forming units (CFU) of the 90 minutes (min) intracellularly viable S. aureus were administered (i.v.) per mouse through 0.1 ml saline.


METHODS
Anti-oxidant enzyme assay, phagocytic activity, H2O2 release, Zymography for catalase, serum tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) level were estimated. One-way Model I ANOVA and one tail Student's t-test were performed.


RESULTS
Survival of S. aureus was least after 90 min of reincubation within macrophages. Maximum amount of bacterial anti-oxidant enzymes were released after 90 min of re-incubation. H2O2 released after 90 min of re-incubation with S. aureus was maximum. Higher activity of catalase and SOD by S. aureus occurred in response to the gradual production of H2O2. Serum IL-6 and TNF-alpha was also elevated 1h post infection.


CONCLUSIONS
Bacterial catalase and SOD combat reactive oxygen species enabling S. aureus to persist within macrophages, inducing local inflammation, causing greater induction of serum TNF-alpha and IL-6.
Das
D
D
Department of Physiology, Immunology Laboratory, University of Calcutta, 92, APC Road, Kolkata, 700009, West Bengal, India.
Saha
S S
SS
Bishayi
B
B
D000818:Animals; D000975:Antioxidants / Q000378:metabolism / Q000494:pharmacology; D002374:Catalase / Q000096:biosynthesis* / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015850:Interleukin-6 / Q000378:metabolism; D008264:Macrophages / Q000382:microbiology*; D017737:Macrophages, Peritoneal / Q000378:metabolism; D008297:Male; D051379:Mice; D008954:Models, Biological; D013211:Staphylococcus aureus / Q000378:metabolism*; D013234:Stem Cells; D013482:Superoxide Dismutase / Q000096:biosynthesis*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D000975:Antioxidants; D016207:Cytokines; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D006861:Hydrogen Peroxide; D002374:Catalase; D013482:Superoxide Dismutase