Michael Andreas Kandler

High frequency oscillatory ventilation suppresses inflammatory response in lung tissue and microdissected alveolar macrophages in surfactant depleted piglets.

The impact of high frequency oscillatory ventilation (HFOV) compared with intermittent mandatory ventilation (IMV) on oxygenation and pulmonary inflammatory response was studied in a surfactant depleted piglet model. After establishment of lung injury by bronchoalveolar lavage, piglets either received HFOV (n =5) or IMV (control; n = 5) for eight hours. Pao2 was higher and mean pulmonary arterial pressure (MPAP) was lower with HFOV (HFOV versus control, mean ± SEM; endpoint paO2: 252 ± 73 versus 68 ± 8.4 mm Hg; p < 0.001; MPAP: 22 ± 2.3 versus 34 ± 2.5 mm Hg; p < 0.01). mRNA expression of interleukin (IL)-1β, IL-6, IL-8, IL-10, TGF-β1, Endothelin-1, and adhesion molecules (E-selectin, P-selectin, ICAM-1) in lung tissue was quantified by real time PCR normalized to β-actin and hypoxanthine-guanine-phosphoribosyl-transferase (HPRT). mRNA expression of all cytokines and adhesion molecules/HPRT was higher in controls (e.g.: HFOV versus control, mean ± SEM; IL-1β/HPRT: 1.6 ± 0.3 versus 23.1 ± 8.6 relative units (RU), p < 0.001; IL-8/HPRT: 8.5 ± 2.0 versus 63.5 ± 15.2 RU, p < 0.001). IL-8/HPRT gene expression was quantified in microdissected single cells. With HFOV, IL-8 gene expression was highly reduced in alveolar macrophages: 10 ± 3.4 copies IL-8 mRNA/copy HPRT mRNA versus 356 ± 142; p < 0.05 (bronchiolar epithelial cells: 33 ± 16 versus 208 ± 108; alveolar septum: 2.1 ± 1.3 versus 26 ± 11; bronchiolar smooth muscle cells: 1.3 ± 0.3 versus 2.8 ± 1.0; vascular smooth muscle cells: 0.7 ± 0.3 versus 1.1 ± 0.4). In conclusion, HFOV improved oxygenation, reduced pulmonary arterial pressure and attenuated pulmonary inflammatory response.

Aerosolized perfluorocarbon suppresses early pulmonary inflammatory response in a surfactant-depleted piglet model

The effect of new ventilation strategies on initial pulmonary inflammatory reaction was studied in a surfactant-depleted piglet model. Sixty minutes after induction of lung injury by bronchoalveolar lavage, piglets received either aerosolized FC77 (aerosol-PFC, 10 mL/kg/h, n = 5) or partial liquid ventilation (PLV) with FC77 at functional residual capacity volume (FRC-PLV, 30 mL/kg, n = 5), or at low volume (LV-PLV, 10 mL/kg per hour, n = 5), or intermittent mandatory ventilation (control, n = 5). After 2 h, perfluorocarbon application was stopped and intermittent mandatory ventilation continued for 6 h. After a total experimental period of 8 h, animals were killed and lung tissue obtained. mRNA expression of IL-1β, IL-6, IL-8, and TGF-β in porcine lung tissue was quantified using TaqMan real-time PCR and normalized to β-actin (A) and hypoxanthine-guanine-phosphoribosyl-transferase (H). In the aerosol-PFC group, IL-1β, IL-6, IL-8, and transforming growth factor (TGF)-β mRNA expression in lung tissue was significantly lower than in the control group. Reduction was 95% for IL-1β/H (p < 0.001), 73% for IL-6/H (p < 0.05), 87% for IL-8/H (p < 0.001), and 38% for TGF-β/H (p < 0.01). A lower mRNA gene expression was also determined for IL-1β and IL-8 when the aerosol-PFC group was compared with the LV-PLV group [91% for IL-1β/H (p < 0.001), 75% for IL-8/H (p < 0.001)]. In the FRC-PLV group, mRNA expression of IL-1β was significantly lower than in the control (p < 0.05) and LV-PLV (p < 0.01) group. In a surfactant-depleted piglet model, aerosol therapy with perfluorocarbon but not LV-PLV reduces the initial pulmonary inflammatory reaction at least as potently as PLV at FRC volume.

Comparison of aerosol therapy with different perfluorocarbons in surfactant-depleted animals

Objective:The study investigates the effectiveness of aerosol treatment on gas exchange and pulmonary inflammatory reaction using perfluorocarbons with different molecular structure and vapor pressure. Design:Experimental, prospective, randomized, controlled study. Setting:Experimental laboratory at a university hospital. Subjects:Twenty anesthetized neonatal piglets assigned to four groups. Interventions:After establishment of lung injury by bronchoalveolar lavage, piglets either received aerosolized FC77 (n = 5), perfluorooctylbromide (n = 5), or FC43 (n = 5, 10 mL·kg−1·hr−1 for 2 hrs) or intermittent mandatory ventilation (control, n = 5). Thereafter, animals were supported for another 6 hrs. Measurements and Main Results:PaO2 significantly improved in the perfluorocarbon groups compared with control (p < .01). Final PaO2 (mean ± sem) was FC77, 406 ± 27 mm Hg; perfluorooctylbromide, 332 ± 32 mm Hg; FC43, 406 ± 19 mm Hg; control, 68 ± 8 mm Hg. PaCO2 and mean pulmonary arterial pressure were lower in all perfluorocarbon groups compared with control. The ratio of terminal dynamic compliance to total compliance was significantly higher in the FC77 than in the FC43, perfluorooctylbromide, and control groups. Relative gene expression of interleukin-1β, interleukin-8, P-selectin, E-selectin, and intercellular adhesion molecule-1 in lung tissue was determined by TaqMan real time polymerase chain reaction normalized to hypoxanthine-guanine-phosphoribosyl-transferase and was shown to be reduced by all perfluorocarbons. Conclusions:Aerosol treatment with all the perfluorocarbons investigated improved gas exchange and reduced pulmonary inflammatory reaction independently from molecular structure and vapor pressure of the perfluorocarbons. Although differences in vapor pressure and molecular structure may account for varying optimal dosing strategies, several different perfluorocarbons were shown to be principally suitable for aerosol treatment.

Aerosolized adrenomedullin suppresses pulmonary transforming growth factor-β1 and interleukin-1β gene expression in vivo

The effect of aerosolized adrenomedullin on interleukin-1β and transforming growth factor (TGF)-β1 mRNA and protein expression was studied in surfactant depleted piglets, receiving aerosolized adrenomedullin (adrenomedullin, n=6), aerosolized adrenomedullin plus i.v. NG-nitro-l-arginine-methylester (adrenomedullin+l-NAME, n=5), or aerosolized saline solution (control, n=6). After 8 h of aerosol interval therapy, mRNA expression of interleukin-1β and TGF-β1 in lung tissue was quantified normalized to β-actin and hypoxanthine-guanine-phosphoribosyl-transferase by real-time polymerase chain reaction (PCR). Interleukin-1β and TGF-β1 protein concentration in lung tissue was quantified by enzyme-linked immunosorbent assay (ELISA). In the adrenomedullin group, interleukin-1β and TGF-β1 mRNA expression was lower than in controls. Reduction for interleukin-1β/β-actin was 56% (p<0.001), for interleukin-1β/hypoxanthine-guanine-phosphoribosyl-transferase 60% (p<0.001), for TGF-β1/β-actin 65.5% (p<0.001), and for TGF-β1/hypoxanthine-guanine-phosphoribosyl-transferase 56.2% (p<0.001). Mean interleukin-1β protein expression was different between the groups, p<0.05 (adrenomedullin 601±61, Control 836±88 pg/mg protein). l-NAME did not antagonize adrenomedullin effect on TGF-β1 mRNA. In conclusion, aerosolized adrenomedullin reduced pulmonary inflammatory and pro-fibrotic response.

Aerosolized perfluorocarbon reduces adhesion molecule gene expression and neutrophil sequestration in acute respiratory distress

In acute respiratory distress syndrome, neutrophil migration into the lung plays a key role in the development of lung injury. To study the effect of different modes of ventilation with perfluorocarbon (FC77), intrapulmonary neutrophil accumulation and mRNA expression of E-selectin, P-selectin and intercellular adhesion molecule-1 (ICAM-1), mediating leukocyte sequestration, were measured in surfactant depleted piglets. After bronchoalveolar lavage, 20 animals either received aerosolized perfluorocarbon (Aerosol-PFC), partial liquid ventilation (PLV) with perfluorocarbon at functional residual capacity filling volume (FRC-PLV) or at low volume (LV-PLV) or intermittent mandatory ventilation (control). After 2 h of perfluorocarbon application, intermittent mandatory ventilation was continued for 6 h. In the Aerosol-PFC group, all measured adhesion molecules showed a significantly reduced gene expression compared to controls. FRC-PFC treatment was effective in significantly diminishing P-selectin and ICAM-1 mRNA expression. Relative lung tissue neutrophil counts were significantly reduced in the Aerosol-PFC and the FRC-PLV group. Treatment with aerosolized perfluorocarbon is at least as effective as partial liquid ventilation at FRC volume in reducing pulmonary adhesion molecule expression and neutrophil accumulation in acute respiratory distress syndrome.

Brief adrenomedullin inhalation leads to sustained reduction of pulmonary artery pressure

The effect of aerosolised adrenomedullin (ADM), a potent vasodilator peptide, on pulmonary artery pressure was studied for 24 h in a surfactant-depleted piglet model. Animals received either aerosolised ADM (50 ng·kg−1·min−1, ADM, n=6), or aerosolised normal saline solution (control, n=6). Aerosol therapy was performed for a 2 h treatment period followed by a 22 h observation period. Ventilator settings were adapted to keep arterial oxygen tension and carbon dioxide arterial tension between 13.3–14.6 kPa and 4.9–5.7 kPa, respectively. Aerosolised ADM reduced mean pulmonary artery pressure (MPAP) compared with the control group (end-point median 24 h after therapy start: ΔMPAP −14.0 versus −8.0 mmHg; 23.5 h after therapy start). After therapy start, mean systemic arterial pressure (MAP) was not significantly different between the groups (end-point median: MAP ADM 70 (61/74) versus control 72 (54/81) mmHg). Endothelin-1, a potent pulmonary vasoconstrictor, is regulated by ADM via cAMP. Twenty two hours after inhalation of aerosolised ADM, endothelin-1 mRNA in lung tissue and endothelin-1 protein expression in pulmonary arteries was reduced compared with controls (median semi-quantitative immunhistochemical score: ADM 0.21, control 0.76). Aerosolised adrenomedullin significantly reduced mean pulmonary artery pressure independently of arterial oxygen tension.

Dose response to aerosolized perflubron in a neonatal swine model of lung injury.

Aerosolized perfluorocarbon (PFC) improves gas exchange, lung mechanics, and pulmonary artery pressure. The objective of this intervention was to study the dose-response effect to aerosolized perfluorooctylbromide (PFOB; perflubron, LiquiVent, Alliance Pharmaceutical Corp.) in surfactant-depleted piglets. After induction of lung injury by saline lavage, 25 newborn piglets were randomly assigned to receive 0, 1.25, 2.5, 5.0, or 7.5 mL/kg aerosolized PFOB per hour. A 2-h therapy period was followed by a 3-h observation period. In all animals, respiratory support was performed with intermittent mandatory ventilation. After aerosol treatment and 3 h of observation, arterial oxygen pressure was similarly improved in the 2.5-, 5.0-, and 7.5-mL·kg−1·h−1 aerosol-PFOB groups and higher compared with the 1.25-mL·kg−1·h−1 aerosol-PFOB (P < 0.01) and the control groups (P < 0.001). Compared with the control group, arterial carbon dioxide pressure was significantly reduced with 2.5-, 5.0-, and 7.5-mL·kg−1·h−1 aerosol-PFOB (P < 0.001). Treatment with 1.25 mL·kg−1·h−1 aerosol-PFOB did not significantly affect arterial carbon dioxide pressure. The 20% terminal dynamic compliance/dynamic compliance was significantly improved in the groups that received 2.5, 5.0, and 7.5 mL·kg−1·h−1 aerosol-PFOB compared with control animals. Mean pulmonary artery pressure was lower after therapy with 5.0 and 7.5 mL·kg−1·h−1 aerosol-PFOB (P < 0.01) than in the control group. IL-1β gene expression in lung tissue was significantly reduced with PFOB 1.25 mL·kg−1·h−1. In summary, aerosolized PFOB improved terminal dynamic compliance, pulmonary gas exchange, and pulmonary artery pressure in a dose-dependent manner. In terms of oxygenation and lung mechanics, the optimum dose was between 2.5 and 5 mL·kg−1·h−1.

Anakinra (IL-1R antagonist) lowers pulmonary artery pressure in a neonatal surfactant depleted piglet model.

In acute respiratory distress syndrome (ARDS) with pulmonary hypertension, interleukin‐1β (IL‐1β) and interleukin‐8 (IL‐8) are involved in the pulmonary inflammatory reaction. The purpose of this study was to determine whether systemic and aerosolized administered IL‐1 receptor antagonist (IL‐1Ra) Anakinra (Kineret™) improves lung mechanics and pulmonary artery pressure in surfactant depleted newborn piglets. After induction of acute lung injury by lung lavage, neonatal piglets received repetitive treatment of either aerosolized IL‐1Ra (IL‐1Ra‐Aerosol) or intravenous IL‐1Ra (IL‐1Ra‐i.v.), or saline solution as control. IL‐1Ra given as aerosol or intravenously significantly reduced mean pulmonary artery pressure (MPAP) but did not influence mean systemic arterial pressure (MAP) compared with the control group. IL‐1β and IL‐8 mRNA expressions normalized to β‐actin and hypoxanthine‐guanine‐phosphoribosyl transferase were significantly reduced in the IL‐1Ra‐Aerosol group but not in IL‐1Ra‐i.v. group compared to the control group. The lung injury score was not significantly different between IL‐1Ra groups and the control group. Application of aerosolized IL‐1Ra reduced MPAP without affecting MAP in a piglet model of surfactant depletion with pulmonary hypertension. Furthermore, there is evidence for reduction of early pro‐inflammatory pulmonary reaction. Pediatr Pulmonol. 2008; 43:851–857.

Parecoxib does not suppress thromboxane synthesis in newborn piglets with group B streptococcal sepsis.

Group B streptococci (GBS) cause fatal sepsis in newborns. Strong activation of thromboxane synthesis is assumed to correlate with severe pulmonary hypertension. In this study we compared the impact of indomethacin versus parecoxib on hemodynamics and outcome and investigated the pharmacological effects on thromboxane synthesis and EP-3 receptor gene expression. Whereas both parecoxib and indometacin reduced expression of thromboxane synthase and EP-3 receptor in infected lung tissue, parecoxib did not suppress urine levels of thromboxane like indometacin. We presume that COX-2 inhibition in GBS sepsis is associated with enhanced thrombogenicity.