Antibiotics improve survival and alter the inflammatory profile in a murine model of sepsis from Pseudomonas aeruginosa pneumonia.
ABSTRACT Differing antibiotic regimens can influence both survival and the inflammatory state in sepsis. We investigated whether the addition and/or type of antimicrobial agent could effect mortality in a murine model of Pseudomonas aeruginosa pneumonia-induced sepsis and if antibiotics altered systemic levels of cytokines. FVB/N mice were subjected to intratracheal injection of pathogenic bacteria and were given gentamicin, imipenem, or 0.9% NaCl 2 h after surgery, which continued every 12 h for a total of six doses. Survival at 7 days (n = 24 in each group) was 100% for mice given gentamicin, 88% for mice given imipenem, and 8% for sham mice treated with 0.9% NaCl (P < 0.0001). Systemic interleukin (IL) 6 levels were assayed 6 h postoperatively on all mice to see if they were predictive of outcome. Plasma IL-6 levels above 3,600 pg/mL were associated with a 100% mortality, levels under 1,200 pg/mL were associated with a 100% survival, and levels between 1,200 and 3,600 pg/mL had no utility in predicting mortality. In a separate experiment, mice were sacrificed at 3, 6, 12 or 24 h after instillation of P. aeruginosa and were assayed for levels of TNF-alpha, IL-6, IL-10, and IL-12. Significant alterations in the proinflammatory cytokines TNF-alpha and IL-6 were present at all time points except 3 h between mice treated with antibiotics and sham controls. In contrast, statistically significant differences in the anti-inflammatory cytokine IL-10 were present between the groups only at 6 h, and levels of IL-12 were similar at all time points. These results indicate that both gentamicin and imipenem increase survival at least 10-fold in a model of pneumonia-induced monomicrobial sepsis, and this is predominantly associated with a down-regulation of proinflammatory cytokines.
- SourceAvailable from: ncbi.nlm.nih.gov[show abstract] [hide abstract]
ABSTRACT: To assess at serial intervals the production of interleukin-12 (IL-12) by monocytes/macrophages from the peripheral blood of injured patients and control subjects, and using a mouse model to confirm human findings and explore the effectiveness of low-dose IL-12 therapy in restoring resistance to infection after injury. Serious injury is associated with loss of function of the T helper 1 lymphocyte phenotype, but little is known about IL-12 production in injured patients. The authors previously reported that early, moderate-dose IL-12 therapy in a mouse model of burn injury restored resistance to a later infectious challenge (cecal ligation and puncture, CLP). However, the efficacy of clinically relevant low-dose IL-12 therapy carried out to or beyond the time of septic challenge remains to be tested. Peripheral blood mononuclear cells (PBMCs) and adherent cells were obtained from 27 patients with major burns or traumatic injury and 18 healthy persons and were studied at serial intervals for IL-12 production stimulated by bacterial lipopolysacharide (LPS). PBMCs from 18 of the same patients were studied for IL-10 production as well. IL-12 production by adherent cells from the spleens of burn or sham burn mice was studied at serial intervals after injury to confirm the human findings. Low-dose IL-12 or vehicle was given every other day to groups of burn and sham burn mice, which were then challenged with CLP on day 10, and survival was determined. Finally, spleens were harvested from burn or sham burn animals receiving low-dose IL-12 or vehicle after CLP. After splenic cellularity was determined by hemocytometer, splenocytes were cultured and production of tumor necrosis factor-alpha, interferon-gamma, and IL-10 were assessed by immunoassay. Adherent cells from patients' PBMCs produced significantly less IL-12 than normal PBMCs after injury, reaching a nadir 8 to 14 days after injury. Stimulation of whole PBMCs by LPS indicated that at 8 to 14 days after injury, IL-12 production by PBMCs was significantly lower and IL-10 production was significantly higher than that of PBMCs from healthy persons. Low-dose IL-12 therapy significantly increased survival after CLP. Splenocytes from burn mice treated with IL-12 had significantly increased production of TNF-alpha and IF-beta, both before and after CLP, when compared with vehicle-treated burn animals. IL-10 production by bum splenocytes remained high after IL-12 treatment. Splenic cellularity increased after IL-12 treatment in burn mice. The capacity to produce IL-12 by adherent cells of the monocyte/macrophage lineage is significantly reduced after serious injury in humans and in a mouse burn model. In humans, there is a reciprocal relation between diminished IL-12 production and increased IL-10 production at approximately 1 week after injury. Low-dose IL-12 therapy in the mouse burn model markedly increased survival after a septic challenge, even when treatment was carried beyond the onset of sepsis. Low-dose IL-12 treatment in the mouse increased production of proinflammatory mediators important in host defense and at the same time maintained or increased production of IL-10, an important antiinflammatory cytokine.Annals of Surgery 03/2000; 231(2):253-61. · 6.33 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Pseudomonas aeruginosa is the most frequent Gram-negative pathogen causing nosocomial pneumonia. Four different strains of P. aeruginosa (including three isogenic transposon mutants) were utilized in experiments in mice to characterize the specific patterns of cytokine generation in response to bacterial products and cytotoxicity. Intratracheal instillation of any of the strains led to the up-regulation of IL-1beta, IL-6, and TNF-alpha mRNA. Instillation of the cytotoxic strains (PA103, PA103tox::omega) led to IL-10 mRNA up-regulation in the lungs and increased concentrations of IL-10 in the blood. In contrast, the instillation of the noncytotoxic strains (PA01, PA103exsA::omega) did not lead to an increase in IL-10 mRNA in the lungs or to an increase of IL-10 concentration in blood. IL-10 production appears to be a response to either cellular injury or to specific cytotoxic exoproducts produced by the bacteria. The systemic administration of rIL-10 significantly decreased the lung injury and the mortality in mice who had received the cytotoxic strains. The improvement in survival induced by administration of rIL-10 required the concomitant presence of IFN-gamma, as blockade of IFN-gamma with a neutralizing Ab led to 100% mortality, despite the administration of rIL-10. These results suggest that IL-10 is produced in response to specific bacterial products and that there is a potential role for IL-10 in the treatment of cytotoxic P. aeruginosa pneumonia.The Journal of Immunology 10/1997; 159(6):2858-66. · 5.52 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: A murine model was used to test the effects of various therapeutic modalities on the rate of death following intra-abdominal sepsis as produced by cecal ligation and puncture (CLP). There were no deaths among sham-operated control mice after ether anesthesia, whereas CLP produced a mortality rate of 100% by 24 hours. When CLP was followed at 16 hours by excision of the cecum and saline peritoneal lavage (CLPE), the mortality rate was 20% at 24 hours and 60% at 72 hours. The therapeutic modalities consisted of gentamicin (1.5 mg/kg) alone or in combination with methylprednisolone (50 mg/kg) or tuftsin (1 mg/kg) administered before CLP and at 16 and 24 hours after CLP. Separate groups of animals also received only methylprednisolone or tuftsin, a tetrapeptide produced by the spleen. Compared with the mortality rate in the CLPE group, mortality at 24 and 72 hours was decreased for gentamicin alone (0% and 10%, respectively), tuftsin alone (10%, 40%), or the two in combination (0%, 20%). As compared with CLPE, methylprednisolone led to increased mortality rates at 24 and 72 hours (70%, 80%). The data (significant at P less than 0.01, X2 analysis) suggest that gentamicin and tuftsin may improve the rate of early survival after intra-abdominal sepsis in this Model. Steroids do not seem to be beneficial and may, in fact, be harmful.Surgery 09/1983; 94(2):331-5. · 3.37 Impact Factor