In vivo efficacy of sivelestat in combination with pazufloxacin against Legionella pneumonia

Clinically relevant model of pneumococcal pneumonia, ARDS, and nonpulmonary organ dysfunction in mice

Pneumonia is responsible for more deaths in the United States than any other infectious disease. Severe pneumonia is a common cause of acute respiratory failure and acute respiratory distress syndrome (ARDS). Despite the introduction of effective antibiotics and intensive supportive care in the 20th century, death rates from community-acquired pneumonia among patients in the intensive care unit remain as high as 35%. Beyond antimicrobial treatment, no targeted molecular therapies have yet proven effective, highlighting the need for additional research. Despite some limitations, small animal models of pneumonia and the mechanistic insights they produce are likely to continue to play an important role in generating new therapeutic targets. Here we describe the development of an innovative mouse model of pneumococcal pneumonia developed for enhanced clinical relevance. We first reviewed the literature of small animal models of bacterial pneumonia that incorporated antibiotics. We then did a series of experiments in mice in which we systematically varied the pneumococcal inoculum and the timing of antibiotics while measuring systemic and lung-specific end points, producing a range of models that mirrors the spectrum of pneumococcal lung disease in patients, from mild self-resolving infection to severe pneumonia refractory to antibiotics. A delay in antibiotic treatment resulted in ongoing inflammation and renal and hepatic dysfunction despite effective bacterial killing. The addition of fluid resuscitation to the model improved renal function but worsened the severity of lung injury based on direct measurements of pulmonary edema and lung compliance, analogous to patients with pneumonia and sepsis who develop ARDS following fluid administration.

In vivo efficacy of KRP-109, a novel elastase inhibitor, in a murine model of severe pneumococcal pneumonia

KRP-109 is a novel specific inhibitor of neutrophil elastase (NE). Various studies suggest that NE inhibitors reduce lung injury associated with systemic inflammatory response syndrome (SIRS). In this study, the efficacy of KRP-109 was examined using a murine model of severe pneumonia induced by Streptococcus pneumoniae (S. pneumoniae). Female mice (CBA/J, aged 5 weeks) were inoculated intranasally with penicillin-susceptible S. pneumoniae (ATCC49619 strain, 2.5 × 10(8) CFU/mouse). KRP-109 (30 or 50 mg/kg) or physiological saline as a control was administered intraperitoneally every 8 h beginning at 8 h after inoculation, and survival rate was evaluated over 7 days. Histopathological and bacteriological analyses of the lung, and bronchoalveolar lavage were performed at 48 h post-infection. The mice treated with KRP-109 (KRP-109 mice) tended to have higher survival rate than those given saline. The lung tissues of the KRP-109 mice had few neutrophils in the alveolar walls and less inflammation. Furthermore, KRP-109 decreased significantly total cell and neutrophil counts, and cytokine levels (interleukin 1β and macrophage inflammatory protein 2) in bronchoalveolar lavage fluid. Viable bacterial numbers in lung were not influenced by treatment of KRP-109. The present results indicate that KRP-109 reduces lung inflammation in a murine model, and that KRP-109 may be useful for the treatment of patients with severe pneumonia.