Killing of S. aureus in murine peritoneal macrophages by Ascorbic acid along with antibiotics Chloramphenicol or Ofloxacin: Correlation with inflammation

Abstract

Alarming increase of death due to S. aureus sepsis demands newer treatment strategies. Enhancement of antibiotic resistant S. aureus strains caused increased mortality. Only antibiotic treatment for Staphylococcal sepsis has been found insufficient to improve outcomes. In the innate immune response, phagocytosis mediated killing of pathogen and further triggering of intracellular signaling cascades by the PRRs culminates in the release of a variety of pro inflammatory cytokines, which orchestrate together in the early host response to infection. Increased production of inflammatory cytokines not only delineate pathogen burden but also affects host cell by triggering inflammation. Therefore, combinational therapy of Ascorbic acid is used along with antibiotics Ofloxacin (OFX) or Chloramphenicol (CHL) to kill S. aureus by mouse peritoneal macrophages. For this ROS like H2O2, superoxide anion and NO production was accessed, TLR2 and COX2 expression was monitored. Pro-inflammatory cytokines along with antioxidant levels were also analyzed. Ascorbic acid along with antibiotics OFX or CHL promoted bacterial clearance at early infection by increasing H2O2 and O2−.NO production has been found to decrease, providing protection against harmful per-oxynitril ion. Increase in TLR-2 expression resulted in enhanced phagocytosis and subsequently more killing. Treatment with Ascorbic acid decreased proinflammatory cytokines and inflammatory markers like iNOS and COX2. This combination increased antioxidant enzymes like SOD, Catalase, GSH as well as decreased LPO, thus balancing ROS and antioxidant status inside the cell. Thus in-vitro augmentation of bacterial clearance along with regulated inflammation as found by decrease in proinflammatory cytokines like TNF-α IFN-γ,IL-6 and inflammatory markers like COX2 may be considered as a novel and important therapeutic strategy.