Comparison of the effect of LPS and PAM3 on ventilated lungs.

BACKGROUND: While lipopolysaccharide (LPS) from Gram-negative bacteria has been shown to augment inflammation in ventilated lungs information on the effect of Gram-positive bacteria is lacking. Therefore the effect of LPS and a lipopetide from Gram-positive bacteria, PAM3, on ventilated lungs were investigated. METHODS: C57/Bl6 mice were mechanically ventilated. Sterile saline (sham) and different concentrations of LPS (1 microg and 5 microg) and PAM3 (50 nM and 200 nM) were applied intratracheally. Lung function parameters and expression of MIP-2 and TNFalpha as well as influx of neutrophils were measured. RESULTS: Mechanical ventilation increased resistance and decreased compliance over time. PAM3 but not LPS significantly increased resistance compared to sham challenge (P < 0.05). Both LPS and PAM3 significantly increased MIP-2 and TNFalpha mRNA expression compared to sham challenge (P < 0.05). The numbers of neutrophils were significantly increased after LPS at a concentration of 5 microg compared to sham (P < 0.05). PAM3 significantly increased the numbers of neutrophils at both concentrations compared to sham (P < 0.05). CONCLUSIONS: These data suggest that PAM3 similar to LPS enhances ventilator-induced inflammation. Moreover, PAM3 but not LPS increases pulmonary resistance in ventilated lungs. Further studies are warranted to define the role of lipopetides in ventilator-associated lung injury.

Effect of low tidal volume ventilation on lung function and inflammation in mice.

BACKGROUND: A large number of studies have investigated the effects of high tidal volume ventilation in mouse models. In contrast data on very short term effects of low tidal volume ventilation are sparse. Therefore we investigated the functional and structural effects of low tidal volume ventilation in mice. METHODS: 38 Male C57/Bl6 mice were ventilated with different tidal volumes (Vt 5, 7, and 10 ml/kg) without or with application of PEEP (2 cm H2O). Four spontaneously breathing animals served as controls. Oxygen saturation and pulse rate were monitored. Lung function was measured every 5 min for at least 30 min. Afterwards lungs were removed and histological sections were stained for measurement of infiltration with polymorphonuclear leukocytes (PMN). Moreover, mRNA expression of macrophage inflammatory protein (MIP)-2 and tumor necrosis factor (TNF)alpha in the lungs was quantified using real time PCR. RESULTS: Oxygen saturation did not change significantly over time of ventilation in all groups (P > 0.05). Pulse rate dropped in all groups without PEEP during mechanical ventilation. In contrast, in the groups with PEEP pulse rate increased over time. These effects were not statistically significant (P > 0.05). Tissue damping (G) and tissue elastance (H) were significantly increased in all groups after 30 min of ventilation (P < 0.05). Only the group with a Vt of 10 ml/kg and PEEP did not show a significant increase in H (P > 0.05). Mechanical ventilation significantly increased infiltration of the lungs with PMN (P < 0.05). Expression of MIP-2 was significantly induced by mechanical ventilation in all groups (P < 0.05). MIP-2 mRNA expression was lowest in the group with a Vt of 10 ml/kg + PEEP. CONCLUSIONS: Our data show that very short term mechanical ventilation with lower tidal volumes than 10 ml/kg did not reduce inflammation additionally. Formation of atelectasis and inadequate oxygenation with very low tidal volumes may be important factors. Application of PEEP attenuated inflammation.

Experimental approaches towards allergic asthma therapy-murine asthma models.

Allergic bronchial asthma is a chronic inflammatory disorder of the airways characterized by a T helper 2 (TH2) cell triggered airway eosinophilia, development of airway hyperresponsiveness, mucus hyper secretion and structural changes of the airway wall summarized as airway remodeling. Current asthma therapy aims at controlling the inflammatory response in the airways by using corticosteroids in mild-moderate asthmatics. With increasing disease severity addition of further medication is required and includes long acting beta(2)-agonists or even immune suppressive drugs such as azathioprine, methotrexate or cyclophosphamide. Due to considerable side effects of these drugs especially underhigh dose treatment conditions controlling moderate-severe asthma represents an unmet medical need. Over the last 15 years mouse models of allergic asthma increased the knowledge about the pathophysiology of allergic asthma dramatically and led to several new therapeutic approaches such as the development of a monoclonal antibody against IgE. However, since TH2 cells seem to play a pivotal role in orchestrating the inflammatory response underlying asthma pathology these cells are predisposed as targets for therapeutic intervention. Thus, the present article further discusses several relevant patents and the current status of experimental approaches towards asthma therapy that aim at neutralizing TH2 cell effector functions, TH2 cell development, TH2 cell recruitment, and immunomodulation.

PAS staining of bronchoalveolar lavage cells for differential diagnosis of interstitial lung disease.

Bronchoalveolar lavage (BAL) is a useful diagnostic tool in interstitial lung diseases (ILD). However, differential cell counts are often non specific and immunocytochemistry is time consuming. Staining of glycoproteins by periodic acid Schiff (PAS) reaction may help in discriminating different forms of ILD. In addition, PAS staining is easy to perform. BAL cells from patients with idiopathic pulmonary fibrosis (IPF) (n = 8), sarcoidosis (n = 9), and extrinsic allergic alveolitis (EAA) (n = 2) were investigated. Cytospins from BAL cells were made and cells were stained using Hemacolor quick stain and PAS staining. Lymphocytic alveolitis was found in sarcoidosis and EAA whereas in IPF both lymphocytes and neutrophils were increased. PAS positive cells were significantly decreased in EAA compared to IPF and sarcoidosis (25.5% +/- 0.7% vs 59.8% +/- 25.1% and 64.0% +/- 19.7%, respectively) (P < 0.05). No significant correlation between PAS positive cells and inflammatory cells was observed. These results suggest that PAS staining of BAL cells may provide additional information in the differential diagnosis of ILD. Further studies ware warranted to evaluate PAS staining in larger numbers of BAL from patients with ILD.