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Increased procoagulant activity in the alveolar compartment and uncontrolled inflammation are hallmarks of the acute respiratory distress syndrome (ARDS). Here, we investigated whether the contact phase system of coagulation is activated and may regulate inflammatory responses in human lungs. Components of the contact phase system were characterized in bronchoalveolar lavage fluids (BALF) from 54 ARDS patients and 43 controls, and their impact on cytokine/chemokine expression in human precision cut lung slices (PCLS) was assessed by a PCR array. Activation of the contact system, associated with high levels of coagulation factor XIIa (Hageman factor, FXIIa), plasma kallikrein and bradykinin, occurred rapidly in ARDS lungs after the onset of the disease and virtually normalized within one week from time of diagnosis. FXII levels in BALF were higher in ARDS non-survivors than survivors and were positively correlated with tumor necrosis factor (TNF)-α concentration. FXII induced the production and release of interleukin (IL)-8, IL-1β, IL-6, leukemia inhibitory factor (LIF), CXCL5 and TNF-α in human PCLS in a kallikrein-kinin-independent manner. In conclusion, accumulation of FXII in ARDS lungs may contribute to the release of pro-inflammatory mediators and is associated with clinical outcome. FXII inhibition may thus offer a novel and promising therapeutic approach to antagonize overwhelming inflammatory responses in ARDS lungs without interfering with vital haemostasis.

Prediction of lung innate immune responses is critical for developing new drugs. Well-established immune modulators like lipopolysaccharides (LPS) can elicit a wide range of immunological effects. They are involved in acute lung diseases such as infections or chronic airway diseases such as COPD. LPS has a strong adjuvant activity, but its pyrogenicity has precluded therapeutic use. The bacterial lipopeptide MALP-2 and its synthetic derivative BPPcysMPEG are better tolerated. We have compared the effects of LPS and BPPcysMPEG on the innate immune response in human precision-cut lung slices. Cytokine responses were quantified by ELISA, Luminex, and Meso Scale Discovery technology. The initial response to LPS and BPPcysMPEG was marked by coordinated and significant release of the mediators IL-1β, MIP-1β, and IL-10 in viable PCLS. Stimulation of lung tissue with BPPcysMPEG, however, induced a differential response. While LPS upregulated IFN-γ, BPPcysMPEG did not. This traces back to their signaling pathways via TLR4 and TLR2/6. The calculated exposure doses selected for LPS covered ranges occurring in clinical studies with human beings. Correlation of obtained data with data from human BAL fluid after segmental provocation with endotoxin showed highly comparable effects, resulting in a coefficient of correlation >0.9. Furthermore, we were interested in modulating the response to LPS. Using dexamethasone as an immunosuppressive drug for anti-inflammatory therapy, we found a significant reduction of GM-CSF, IL-1β, and IFN-γ. The PCLS-model offers the unique opportunity to test the efficacy and toxicity of biological agents intended for use by inhalation in a complex setting in humans., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Purpose: To examine the physical properties and chemical composition of particles captured by in-line microfilters in critically ill children, and to investigate the inflammatory and cytotoxic effects of particles on endothelial cells (HUVEC) and macrophages in vitro., Methods: Prospective, observational study of microfilters following their use in the pediatric intensive care unit. In vitro model utilizing cytokine assays to investigate the effects of particles on human endothelial cells and murine macrophages., Results: Twenty filter membranes from nine patients and five controls were examined by electron microscopy (EM) and energy dispersion spectroscopy (EDX). The average number of particles found on the surface of the used membranes was 550 cm(2). EDX analysis confirmed silicon as a major particle constituent. Half of the filter membranes showed conglomerates containing an unaccountable number of smaller particles. In vitro, glass particles were used to mimic the high silicon content particles. HUVEC and murine macrophages were exposed to different contents of particles, and cytokine levels were assayed to assess their immune response. Levels of interleukin-1beta, interleukin-6, interleukin-8, and tumor necrosis factor alpha were suppressed., Conclusions: Particle contamination of infusion solutions exists despite a stringent infusion regiment. The number and composition of particles depends on the complexity of the applied admixtures. Beyond possible physical effects, the suppression of macrophage and endothelial cell cytokine secretion in vitro suggests that microparticle infusion in vivo may have immune-modulating effects. Further clinical trials are necessary to determine whether particle retention by in-line filtration has an influence on the outcome of intensive care patients.

Highlights: [•] Human PCLS were exposed to 4 respiratory, 11 contact allergens, and 5 irritants. [•] Tissue injury and inflammation was assessed by analysis of toxicity and cytokines. [•] Cytotoxicity was concentration-dependently induced by all chemicals except phenol. [•] Only respiratory sensitizers increased TNF-α or IL-1α. [•] Increases in TH1/TH2 cytokines could be detected after exposure to HClPt. [Copyright &y& Elsevier]