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Cytokines and the pathogenesis of nosocomial pneumonia
S G Muehlstedt1, C J Richardson, M A West
1Department of Surgery, Hennepin County Medical Center, University of Minnesota Medical School, Minneapolis 55415, USA.
Background:
Nosocomial pneumonia (NP) in injured patients is a significant clinical problem. We hypothesize that the pathogenesis of NP in injured patients involves an imbalanced cytokine response within the alveolar airspace that may inhibit effector cell function.
Methods:
Proinflammatory (IL-8) and anti-inflammatory (IL-10) levels were measured in bronchoalveolar lavage (BAL) fluid from multitrauma patients on admission, 24, 48, and 72 hours post-injury and following lipopolysaccharide (LPS) induction of alveolar cells. Patients were compared based on IL-8 levels and the development of NP.
Results:
A high level of IL-8 on admission was associated with the development of NP. In addition, levels of IL-8 were significantly greater in NP-positive patients at all time points. The IL-10 levels decreased from admission values in NP-negative patients but increased in NP-positive patients. Furthermore, a high level of IL-10 ( > 120 pg/mL) at 72 hours post-injury was associated with the development of NP. Alveolar cells from NP-positive patients produced significantly more IL-10 in response to LPS than cells from NP-negative patients.
Conclusions:
The pathogenesis of NP in injured patients involves an early and severe IL-8 process within the lung followed by an exaggerated IL-10 response that may inhibit effector cell function.