**Author details**

profile (LXs, cys-LTs, LTB<sup>4</sup>

164 Biomarker - Indicator of Abnormal Physiological Process

ferentiated as much as, for example, asthma from COPD.

become applicable to the clinical settings is still difficult to predict.

**Acknowledgements**

, 8-isoprostane, tyrosines, etc.), which is relevant for diagnostics,

separation, and phenotyping of different respiratory diseases. Nevertheless, EBC analysis requires standardization and validation including sample collection and sample pre-analysis treatment (e.g., internal standardization, storing, pre-treatment method application, etc.).

Model clinical studies were carried out as a part of the work, which applied a methodology based on the molecular diagnostics of EBC. The method allowed an asthma phenotyping, which was founded on the fact that the concentration levels of cys-LTs and LXs are not only complementary but also intra-related by a dynamic equilibrium. This phenomenon, however, affords not only asthma phenotyping but also other diagnostics as, for example, monitoring of efficacy of the used pharmacotherapy. The analysis of EBC also showed that the detected biomarkers can be used for the differentiation of various pulmonary diseases (more specifically (apart from asthma) COPD, asbestosis, and lung cancer). Increased (or decreased) levels of some biomarkers are specific only for some diseases and thus these can be selectively dif-

Additionally, an experiment was conducted and focused on determining serotonin in EBC. The aim of this study was to assess the positive effects of the SSRI (selective serotonin re-uptake inhibitors) antidepressants on SRA. High levels of serotonin were detected in EBC of SRA patients, which was in contradiction to the initial assumption. Simultaneously, a hypothesis was formulated stating that SRA probably functions on different molecular principles. This could have probably been the reason for SRA inefficiency with the commonly used drugs.

For the future research, one can only recommend focusing on large longitudinal studies to ascertain whether sequential measurements in individual patients reflect asthma severity and the degree of a lung inflammation, and on studies engaged to the relationships between the concentrations of asthma biomarkers and its symptoms. In order to implement the EBC analysis to the clinical practice as well as reliably guiding the pharmacological treatment of asthma and the effect of drugs on asthma markers present in EBC, further controlled studies are required to be conducted. In particular, studies are recommended determining the expediency of the EBC analysis for predicting a treatment response, and assessing new therapies. Obviously, this outlines a great deal of work to be done. The fact that EBC analyses are currently used in various clinical trials and studies corroborates the above arguments. On the other hand, it is important to proclaim that the fact whether and when EBC analyses will

The work was supported from The Ministry of Education, Youth and Sports of the Czech Republic under the NPU I (LQ1604) National Sustainability Program II (Project BIOCEV-FAR) and by the project "BIOCEV" (CZ.1.05/1.1.00/02.0109). European Regional Development Fund-Project "PharmaBrain" (No. CZ. CZ.02.1.01/0.0/0.0/16\_025/0007444), project AZV MZ 17-31852A and by the "Sustainability for the National Institute of Mental Health ( LO1611).

Tereza Kačerová1,2, Petr Novotný3 , Ján Boroň<sup>3</sup> and Petr Kačer1, 4\*

