Linezolid has unique immunomodulatory effects in post-influenza community acquired MRSA pneumonia
Urvashi Bhan1, Amy B Podsiad1, Melissa A Kovach1
1Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Michigan Medical Center, Ann Arbor, Michigan, United States of America.
Introduction:
Post influenza pneumonia is a leading cause of mortality and morbidity, with mortality rates approaching 60% when bacterial infections are secondary to multi-drug resistant (MDR) pathogens. Staphylococcus aureus, in particular community acquired MRSA (cMRSA), has emerged as a leading cause of post influenza pneumonia.
Hypothesis:
Linezolid (LZD) prevents acute lung injury in murine model of post influenza bacterial pneumonia.
Methods:
Mice were infected with HINI strain of influenza and then challenged with cMRSA at day 7, treated with antibiotics (LZD or Vanco) or vehicle 6 hours post bacterial challenge and lungs and bronchoalveolar lavage fluid (BAL) harvested at 24 hours for bacterial clearance, inflammatory cell influx, cytokine/chemokine analysis and assessment of lung injury.
Results:
Mice treated with LZD or Vanco had lower bacterial burden in the lung and no systemic dissemination, as compared to the control (no antibiotic) group at 24 hours post bacterial challenge. As compared to animals receiving Vanco, LZD group had significantly lower numbers of neutrophils in the BAL (9×10(3) vs. 2.3×10(4), p < 0.01), which was associated with reduced levels of chemotactic chemokines and inflammatory cytokines KC, MIP-2, IFN-γ, TNF-α and IL-1β in the BAL. Interestingly, LZD treatment also protected mice from lung injury, as assessed by albumin concentration in the BAL post treatment with H1N1 and cMRSA when compared to vanco treatment. Moreover, treatment with LZD was associated with significantly lower levels of PVL toxin in lungs.
Conclusion:
Linezolid has unique immunomodulatory effects on host inflammatory response and lung injury in a murine model of post-viral cMRSA pneumonia.
Insights
Linezolid (LZD) reduces lung injury and inflammation in mice with post-influenza bacterial pneumonia caused by community-acquired MRSA. LZD demonstrates unique immunomodulatory effects, improving outcomes compared to vancomycin.
Area of Science:
- Infectious Diseases
- Pulmonology
- Pharmacology
Background:
- Post-influenza bacterial pneumonia, especially from multidrug-resistant pathogens like community-acquired methicillin-resistant Staphylococcus aureus (cMRSA), is a significant cause of mortality.
- Staphylococcus aureus, particularly cMRSA, is a primary pathogen in severe post-influenza pneumonia cases.
Purpose of the Study:
- To investigate the efficacy of linezolid (LZD) in preventing acute lung injury in a murine model of post-influenza bacterial pneumonia.
- To evaluate the immunomodulatory effects of linezolid on the host inflammatory response.
Main Methods:
- Mice were infected with influenza (H1N1) and subsequently challenged with cMRSA.
- Treatment groups received linezolid (LZD), vancomycin (Vanco), or vehicle 6 hours post-bacterial challenge.
- Lung and bronchoalveolar lavage fluid (BAL) were analyzed for bacterial burden, inflammatory cell influx, cytokine/chemokine levels, and lung injury markers.
Main Results:
- Both LZD and Vanco reduced bacterial burden in the lungs compared to controls.
- LZD treatment resulted in significantly lower neutrophil influx and reduced levels of inflammatory cytokines (KC, MIP-2, IFN-γ, TNF-α, IL-1β) in BAL fluid compared to Vanco.
- LZD treatment demonstrated superior protection against lung injury and reduced Panton-Valentine leukocidin (PVL) toxin levels compared to Vanco.
Conclusions:
- Linezolid exhibits unique immunomodulatory properties in the context of post-viral pneumonia.
- LZD effectively mitigates lung injury and modulates the host inflammatory response in a murine model of cMRSA pneumonia following influenza infection.
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