Lung Defense through IL-8 Carries a Cost of Chronic Lung Remodeling and Impaired Function.

IL-8-dependent inflammation is a hallmark of host lung innate immunity to bacterial pathogens, yet in many human lung diseases, including chronic obstructive pulmonary disease, bronchiectasis, and pulmonary fibrosis, there are progressive, irreversible, pathological changes associated with elevated levels of IL-8 in the lung. To better understand the duality of IL-8-dependent host immunity to bacterial infection and lung pathology, we expressed human IL-8 transgenically in murine bronchial epithelium, and investigated the impact of overexpression on lung bacterial clearance, host immunity, and lung pathology and function. Persistent IL-8 expression in bronchial epithelium resulted in neutrophilia, neutrophil maturation and activation, and chemotaxis. There was enhanced protection against challenge with Pseudomonas aeruginosa, and significant changes in baseline expression of innate and adaptive immunity transcripts for Ccl5, Tlr6, IL-2, and Tlr1. There was increased expression of Tbet and Foxp3 in response to the Pseudomonas antigen OprF, indicating a regulatory T-cell phenotype. However, this enhanced bacterial immunity came at a high price of progressive lung remodeling, with increased inflammation, mucus hypersecretion, and fibrosis. There was increased expression of Ccl3 and reduced expression of Claudin 18 and F11r, with damage to epithelial organization leading to leaky tight junctions, all of which resulted in impaired lung function with reduced compliance, increased resistance, and bronchial hyperreactivity as measured by whole-body plethysmography. These results show that IL-8 overexpression in the bronchial epithelium benefits lung immunity to bacterial infection, but specifically drives lung damage through persistent inflammation, lung remodeling, and damaged tight junctions, leading to impaired lung function.

Evaluation by Monte Carlo simulation of levofloxacin dosing for complicated urinary tract infections caused by Escherichia coli or Pseudomonas aeruginosa.

We evaluated, by Monte Carlo simulation, 500-mg once-daily, 100-mg thrice-daily, 200-mg twice-daily, and 200-mg thrice-daily dose regimens of levofloxacin (LVFX), for the ratio of area under the concentration-time curve for 24 h (AUC(0-24)) to minimum inhibitory concentration (MIC) (AUC(0-24)/MIC) and the ratio of maximum plasma concentration (C(max)) to MIC (C(max)/MIC), which predict microbiological outcomes, and the C(max)/MIC, which inhibits fluoroquinolone resistance selection, in complicated urinary tract infections (UTIs) with Escherichia coli or Pseudomonas aeruginosa. Monte Carlo simulation was performed for 10000 cases using the pharmacokinetic data of patients with complicated UTIs and the LVFX MIC distributions for E. coli or P. aeruginosa clinical strains. The probabilities of achieving the AUC(0-24)/MIC target (66.2-67.9%) and the C(max)/MIC target (64.5-67.5%) to eradicate E. coli were similar among the 4 regimens. In eradication of P. aeruginosa, the 200-mg thrice-daily and the once-daily dose regimens produced higher probabilities of achieving the AUC(0-24)/MIC target (57.5%) and C(max)/MIC target (55.1%), respectively. For the probabilities of achieving the C(max)/MIC targets that prevent the emergence of fluoroquinolone resistance, the once-daily dose regimen (66.8%) did not differ from the other multiple-dose regimens (62.3-66.2%) in E. coli, whereas the former regimen (44.2%) was superior to the latter regimens (10.8-31.7%) in P. aeruginosa. The 500-mg once-daily dose regimen of LVFX, which produced the larger AUC(0-24) and higher C(max), could ensure the efficacy of eradication of uropathogens and reduce the risk of fluoroquinolone resistance selection in complicated UTIs.

Penetration of meropenem into epithelial lining fluid of patients with ventilator-associated pneumonia.

Antibiotic penetration to the infection site is critical for obtaining a good clinical outcome in patients with ventilator-associated pneumonia (VAP). Surprisingly few studies have quantified the penetration of ß-lactam agents into the lung, as measured by the ratio of area under the concentration-time curve (AUC) in epithelial lining fluid (ELF) to AUC in plasma (AUC(ELF)/AUC(plasma) ratio). These have typically involved noninfected patients. This study examines the penetration and pharmacodynamics of meropenem in the ELF among patients with VAP. Meropenem plasma and ELF concentration-time data were obtained from patients in a multicenter clinical trial. Concentration-time profiles in plasma and ELF were simultaneously modeled using a three-compartment model with zero-order infusion and first-order elimination and transfer (big nonparametric adaptive grid [BigNPAG]). A Monte Carlo simulation was performed to estimate the range of ELF/plasma penetration ratios one would expect to observe in patients with VAP, as measured by the AUC(ELF)/AUC(plasma) ratio. The range of AUC(ELF)/AUC(plasma) penetration ratios predicted by the Monte Carlo simulation was large. The 10th percentile of lung penetration was 3.7%, while the 90th percentile of penetration was 178%. The variability of ELF penetration is such that if relatively high ELF exposure targets are required to attain multilog kill or resistance suppression for bacteria like Pseudomonas aeruginosa, then even receiving the largest licensed dose of meropenem with an optimal prolonged infusion may not result in target attainment for a substantial fraction of the population.

Resting energy expenditure before and after treatment for Pseudomonas aeruginosa infection in patients with cystic fibrosis.

To investigate whether metabolic rates change after antipseudomonal treatment, resting energy expenditure (REE) was measured in 29 patients with cystic fibrosis (CF) aged 5-27 y before and after a 2-wk course of intravenous antibiotics for the treatment of chronic Pseudomonas aeruginosa infection. Before therapy, mean (+/- SD) REE was increased to 119.0 +/- 11.4% of the predicted normal value (REE%). Seventeen of the 29 patients were classified as having increased baseline REE% (> 115% of predicted, group I), whereas 12 patients had resting energy expenditures within the normal range (group N). After antipseudomonal therapy, mean REE% decreased significantly by 6.2% of predicted. This decline was negatively correlated with the baseline REE% (r = 0.70, P < 0.001). It was most pronounced (-11.3%) in group I whereas patients of group N showed no major changes. These results suggest that antipseudomonal therapy can reduce increased energy requirements of moderately ill CF patients with chronic Pseudomonas aeruginosa infection.