Influences of nasal lavage collection-, processing- and storage methods on inflammatory markers--evaluation of a method for non-invasive sampling of epithelial lining fluid in cystic fibrosis and other respiratory diseases.

BACKGROUND: Non-invasive sampling of airway epithelial-lining-fluid by nasal lavage (NL) is an emerging method to monitor allergy, infection and inflammation in patients with respiratory diseases. However, the influences of collection-, processing- and storage-methods have not been sufficiently evaluated and standardized. METHODS: Influences of repeated NL, centrifugation setups, repeated freezing and thawing, and protease inhibitors on mediator concentration were evaluated in healthy controls and CF patients, which serve as a model for chronic bacterial infection and inflammation. Polymorphonuclear leukocyte elastase (NE)/myeloperoxidase (MPO)/interleukin (IL)-1/IL-6/IL-8 and tumour necrosis factor alpha (TNF) concentrations were measured using ELISA and Multiplex Bead-Arrays. RESULTS: NL-repetition within 0.5-4h markedly decreased NE, IL-8 and MPO-concentrations for up to 70%. NL centrifugation up to 250×g for cellular differentiation did not significantly influence mediator concentration in native and processed NL fluid. NL freezing and thawing markedly decreased IL-8 and MPO concentrations by up to 50% while NE remained stable. In contrast to preceding reports, storing at -70°C for ≥5 years led to significantly reduced mediator concentrations in NL compared to contemporary analyses, being most pronounced for IL-1ß, IL-6 and TNFa. Storing of samples in the presence of protease inhibitors led to an increase in marker concentration for IL-8 (+27%) and MPO (+15%) even after one year of storage. CONCLUSIONS: NL is an easy and robust technique for inflammation monitoring of the upper airways. For the first time we have shown that diagnostic NL should be performed only once daily to get comparable results. Whereas NL-fluid can be stored unprocessed at -70°C for cytokine analysis over 1-2 years with protease inhibitors supporting stability, ≥5 years storage as well as repeated freezing and thawing should be avoided.

BCR-ABL- and Ras-independent activation of Raf as a novel mechanism of Imatinib resistance in CML.

Although the BCR-ABL tyrosine kinase inhibitor Imatinib has undoubtedly revolutionized the therapy of chronic myeloid leukaemia (CML), acquired drug resistance remains a common problem in CML therapy. Resistance often arises from second-line mutations in BCR-ABL or overexpression of the BCR-ABL protein but in ~20% of CML cases resistance mechanisms do not involve altered BCR-ABL function. Imatinib-resistant CML cell lines have been widely used for comparative proteome/genome-wide expression screens in order to decipher resistance mechanisms but a clearcut molecular mechanism or molecular player in BCR-ABL-independent resistance to Imatinib has not yet evolved from those studies. Here, we report the identification of a novel mechanism for Imatinib resistance in CML cells with unaltered BCR-ABL function. Pharmacological analysis evidenced a constitutive, Imatinib-insensitive activation of the Erk-MAPK pathway in resistant cells. A systematic analysis of pathway constituents illustrated that Ras-GTP accumulation remained fully sensitive to Imatinib but c-Raf activity from serum-fed cultures was largely resistant to the drug's action. Sequencing excluded mutations in either B-Raf or c-Raf as the origin of resistance, indicating that a functional alteration in the regulation of c-Raf activity was responsible for this effect. Collectively, these findings highlight a novel mechanism of acquired Imatinib resistance based on the BCR-ABL and Ras-independent constitutive activation of the Erk-MAPK pathway through activated c-Raf, which could prove helpful for a better functional classification of the causes of Imatinib resistance in CML.

Confirmation of the biological significance of transthyretin as a biomarker for cutaneous T-cell lymphoma by its protein interaction partners.

We previously identified transthyretin (TTR) and its posttranslational modifications as a down-regulated marker in mycosis fungoides (MF), a benign subtype of cutaneous T-cell lymphoma (CTCL). In order to more precisely understand the biological role of TTR in the etiology of MF, it is essential to clarify the pathways of progression by identifying further interacting proteins. This study is the first to combine blue native polyacrylamide gel electrophoresis (BN-PAGE) with surface enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) to detect new TTR interaction partners and to determine whether these TTR interaction partners can themselves be used as biomarkers. By this procedure, apolipoprotein A1, which was additionally found to be down-regulated in the serum of MF patients, apolipoprotein A4, retinol binding protein 4 (RBP-4), and retinoid X receptor ß (RXR-ß) were identified as interaction partners of TTR. The RXR family plays a role in cell differentiation and proliferation and is known to be the target of bexarotene, which is used in the treatment of CTCL. In conclusion, the combination of BN-PAGE and SELDI-TOF-MS used in this study allowed for the detection of protein interaction partners, which, in the case of RBP-4 and RXR, indicated a connection between the common tumor marker TTR and tumor progression in CTCL.

Posttranslational modifications of transthyretin are serum markers in patients with mycosis fungoides.

Cutaneous T-cell lymphomas (CTCLs) are characterized by the recruitment of malignant T-cell clones, predominantly of the CD4(+) T-helper subpopulation, into the skin. Mycosis fungoides (MF) is the most common type of CTCL and accounts for almost 50% of all primary cutaneous lymphomas. The ProteinChip technology surface-enhanced laser desorption/ionization time of flight/mass spectrometry (SELDI-TOF-MS) was used to detect biomarkers in sera from MF patients (n = 25) and healthy controls (n = 26). Therefore, diluted sera were applied to IMAC30 ProteinChip arrays, and the resulting protein profiles were bioinformatically analyzed. A protein set that distinguishes MF patients from healthy controls with a sensitivity of 82.6% and a specificity of 100% was identified. Four significant peaks were identified by two-dimensional gel electrophoresis, immunodepletion, and SELDI-TOF-MS as transthyretin (TTR) and three TTR modifications. A subsequent enzyme-linked immunosorbent assay confirmed these findings. The ability to detect and identify proteins and protein modifications using SELDI-TOF-MS might reveal a better insight on this kind of disease and may lead to a better understanding and earlier detection of MF patients.