Hartmut Kuhn

Exhaled breath condensate acidification in acute lung injury

Lung injury in ventilated lungs may occur due to local or systemic disease and is usually caused by or accompanied by inflammatory processes. Recently, acidification of exhaled breath condensate pH (EBC-pH) has been suggested as marker of inflammation in airway disease. We investigated pH, ammonia, Lactate, pCO2, HCO3-, IL-6 and IL-8 in EBC of 35 ventilated patients (AECC-classification: ARDS: 15, ALI: 12, no lung injury: 8). EBC-pH was decreased in ventilated patients compared to volunteers (5.85 +/- 0.32 vs. 7.46 +/- 0.48; P < 0.0001). NH4+, lactate, HCO3-, pCO2, IL-6 and IL-8 were analyzed in EBC and correlated with EBC-pH. We observed correlations of EBC-pH with markers of local (EBC IL-6: r = -0.71, P < 0.0001, EBC IL-8: r = -0.68, P < 0.0001) but not of systemic inflammation (serum IL-6, serum IL-8) and with indices of severity of lung injury (Murrays Lung Injury Severity Score; r = -0.73, P < 0.0001, paO2/FiO2; r = 0.54, P < 0.001). Among factors potentially contributing to pH of EBC, EBC-lactate and EBC-NH4+ were found to correlate with EBC-pH. Inflammation-induced disturbances of regulatory mechanisms, such as glutaminase systems may result in EBC acidification. EBC-pH is suggested to represent a marker of acute lung injury caused by or accompanied by pulmonary inflammation.

Multiplex Analysis of Cytokines in Exhaled Breath Condensate

To improve monitoring of lung diseases, we analyzed cytokines in exhaled breath condensate (EBC). The main challenge in measurement of cytokines in EBC is the low protein content, which requires concentration steps that conflict with the need for excessive fluid required by most commonly used kits.

Nuclear YB‐1 expression as a negative prognostic marker in nonsmall cell lung cancer

The human Y‐box binding protein, YB‐1, is a multifunctional protein that regulates gene expression. Nuclear expression of YB‐1 has been associated with chemoresistance and poor prognosis of tumour patients. Representative samples from autopsied material of primary tumours from 77 patients with NSCLC were investigated by immunohistochemistry for subcellular distribution of YB‐1 and p53, in order to evaluate the prognostic role of nuclear expression of YB‐1. Cytoplasmic YB‐1 expression was found in all tumour samples, whereas nuclear expression was only observed in 48%. There was no correlation with histological classification, clinical parameters or tumour size, stage and metastasis status. However, patients with positive nuclear YB‐1 expression in tumours showed reduced survival times when compared with patients without nuclear expression. Including information about the histology and mutational status for p53 increased the prognostic value of nuclear YB‐1. Patients with nuclear YB‐1 expression and p53 mutations had the worst prognosis (median survival 3 months), while best outcome was found in patients with no nuclear YB‐1 and wildtype p53 (median survival 15 months). This suggests that the combined analysis of both markers allows a better identification of subgroups with varying prognosis. Nuclear expression of Y‐box binding protien seems to be an independent prognostic marker.

Angiogenic markers in breath condensate identify non-small cell lung cancer

Early recognition of lung cancer is a prerequisite for any strategy to improve lung cancer treatment outcome. Here we report a cross-sectional study intended as a proof of principle investigation using breath based detection (exhaled breath condensate, EBC) of angiogenic markers (VEGF, bFGF, angiogenin), TNF-alpha and IL-8 to discriminate 74 individuals, with confirmed presence or absence (X-ray, CT) of non-small lung cancer (NSCLC). Levels of angiogenic markers bFGF, angiogenin and VEGF in EBC significantly discriminated between 17 individuals with newly detected NSCLC versus stable and exacerbated chronic obstructive pulmonary disease (COPD) patients as well as healthy volunteers. Levels of IL-8 and TNF-alpha in EBC indicated acute inflammation, e.g. in acute exacerbated COPD (AECOPD) and were not indicative of lung cancer. In a different group of patients that were already treated with two cycles of chemotherapy and who responded with at least a 25% reduction in primary tumor diameter, levels of angiogenic markers were lower compared to patients with newly diagnosed NSCLC. We suggest that breath based detection of angiogenic markers may help in the early detection of lung cancer.

BAX and p16INK4A are independent positive prognostic markers for advanced tumour stage of nonsmall cell lung cancer

Clinical studies suggest prognostic relevance of p16INK4A in nonsmall cell lung cancer (NSCLC) while conflicting results for p53 have been published. However, the importance of the apoptosis regulating gene BAX, a downstream regulator of p53, on the prognosis of NSCLC is unknown. The present study investigated the prognostic relevance of BAX with respect to the status of p53 and p16INK4A in 61 patients with advanced NSCLC. Protein expression of BAX, p53 and p16INK4A was investigated retrospectively by immunohistochemistry. Tumour deoxyribonucleic acid (DNA) was screened for p53 mutations by single strand-conformation polymorphism polymerase chain reaction (PCR) and BAX frameshift mutations by fragment length analysis. Patients with positive BAX protein expression had a significantly longer median survival (14 months) than those patients without BAX expression (6 months, p=0.0004). In contrast, p53 status did not influence prognosis. Patients with p16INK4A negative tumours had a significantly shorter survival (4 months) than those with p16INK4A protein expression (15 months, p=0.0001). Furthermore, the loss of p16INK4A protein expression correlated strongly with the pressure of distant and advanced lymph-node metastases. The best survival was seen in a subgroup of 20 patients with positive p16INK4A expression and intact BAX (p=0.0002). The results of the present study suggest that the loss of BAX and p16INK4A expression are independent markers for poor prognosis in nonsmall cell lung cancer. The study suggests that multimarker analysis of genes involved in apoptosis may be useful for determining individual therapy and for identifying targets for gene-replacement therapy. This should be assessed in a prospective study with a larger cohort of patients.

Influence of tidal volume on pulmonary NO release, tissue lipid peroxidation and surfactant phospholipids.

Mechanical stress during ventilation may cause or aggravate acute lung injury. This study investigates the influence of low vs. high tidal volume (V(t)) on factors known to play key roles in acute lung injury: nitric oxide release, eNOS and iNOS gene expression, lipid peroxidation (LPO), and surfactant phospholipids (PL). Isolated rabbit lungs were subjected to one of three ventilation patterns for 135 min (V(t)-PEEP): 6 ml/kg-0 cm H(2)O. 12 ml/kg-0 cm H(2)O 6 ml/kg-5 cm H(2)O, 12 ml/kg-0 cm H(2)O, and 6 ml/kg-5 cm H(2)O resulted in comparable peak inspiratory pressure (PIP). This allowed comparing low and high V(t) without dependence on PIP. Ventilatory patterns did not induce changes in pulmonary artery pressure, vascular permeability (K(f,c)), PIP or pulmonary compliance. High V(t) in comparison with both of the low V(t) groups caused an increase in BALF-nitrite (30.6+/-3.0* vs. 21.4+/-2.2 and 16.2+/-3.3 microM), BALF-PL (1110+/-19* vs. 750+/-68 and 634+/-82 microg/ml), and tissue LPO product accumulation (0.62+/-0.051* vs. 0.48+/-0.052 and 0.43+/-0.031 nmol/mg), *P<0.05 each. Perfusate nitrite and BALF-PL composition (assessed by use of 31P-NMR spectroscopy and MALDI-TOF mass spectrometry) did not differ among the groups. High V(t) ventilation reduced eNOS gene expression but did not affect iNOS expression. The increased release of NO and the accumulation of LPO products may represent early lung injury while elevated BALF-PL may reflect distension-induced surfactant secretion.

Adenovirus-mediated E2F-1 gene transfer in nonsmall-cell lung cancer induces cell growth arrest and apoptosis

Since overexpression of E2F-1 has been shown to induce apoptosis, the ability of adenovirus-mediated transfer of E2F-1 to inhibit tumour growth in nonsmall-cell lung cancer cell lines was investigated. Three cell lines with various genomic status were infected with AdE2F. Cell proliferation and viability were determined by trypan blue exclusion. Apoptosis induction was assessed by flow cytometry and poly-adenosine diphosphate-ribose-polymerase cleavage assay. In vivo, the effect of E2F-1 on tumour growth was determined in severe combined immunodeficiency (SCID) mice. The current experiments showed that overexpression of E2F-1 suppressed tumour cell growth. The population of apoptotic cells was dramatically increased 96 h after infection with AdE2F. Inhibition of cell growth and induction of apoptosis was not dependent on genomic status. Moreover, treatment of implanted tumours in SCID mice with AdE2F inhibited tumour growth. These data suggest that adenovirus-mediated E2F-1 gene therapy may be effective in the treatment of nonsmall-cell lung cancer.

Rapamycin reduces high-amplitude, mechanical stretch-induced apoptosis in pulmonary microvascular endothelial cells

Alveolar epithelial and endothelial cell death caused by mechanical over-distension is likely to contribute to ventilator-induced lung injury (VILI). Consequently, the search for cytoprotective interventions is of interest. We investigated the effect of the mTOR inhibitor rapamycin on human pulmonary microvascular endothelial cell (HMVEC-L) viability in a model of high-amplitude mechanical stretch. Cyclic mechanical stretch (30% increase in membrane surface area, cycling frequency 40/min), employed for 24 h induced apoptosis in HMVEC-L. This effect was reduced by rapamycin treatment. Focusing on possible mechanisms of action we demonstrated that the stretch-induced reduction in the anti-apoptotic messenger pAkt could be restored by rapamycin treatment. Furthermore, we observed rapamycin-induced modifications in the HMVEC-L actin cytoskeleton architecture and global cellular f-actin content which functionally resulted in an increased global cellular mechanical stability - as indicated by an increased HMVEC-L osmomechanical resistance - thereby possibly desensitizing HMVEC-L to mechanical stimulation. According to the data from the present study, rapamycin represents a promising cytoprotective agent under mechanically challenging conditions such as mechanical ventilation.

Interaction of cyclic mechanical stretch and toll-like receptor 4-mediated innate immunity in rat alveolar type II cells.

In cases of infection‐induced acute lung injury, mechanical ventilation might be necessary to maintain oxygenation. Although low tidal volume ventilation is applied, alveolar over‐distension may occur and result in ventilator‐induced lung injury. In this study, we investigate (i) the influence of lipopolysaccharide (LPS) stimulation on high‐amplitude stretching; and (ii) the effect of stretching on LPS‐mediated immune response in isolated rat alveolar type II cells.

High concentrations of vascular endothelial growth factor reduce stretch-induced apoptosis of alveolar type II cells

Background and objective:  Vascular endothelial growth factor (VEGF) is strongly expressed in the alveolar epithelium. VEGF has been shown to exhibit protective as well as injurious effects in ARDS/acute lung injury. We therefore investigated the influence of VEGF in a model of stretch‐induced apoptosis.