Analysis of the levels of monocyte subsets in patients with heart failure.

Abstract

Heart failure is a disorder characterized by different clinical signs and symptoms due to a structural or functional anomaly of the heart. It is the most predominant heart disease in developed countries, both from epidemiological point of view and clinical implications. Indeed, it is a growing medical problem related to major hospitalization needs and high mortality, with significant economic and population burden worldwide. Established prognostic factors, such as age, sex, aetiology, comorbidities, New York Heart Association functional class, left ventricle ejection fraction, and routine laboratory markers might fail to completely and individually predict disease progression and mortality. A good risk stratification strategy is crucial as risk might be refined using several biological biomarkers of different pathophysiological processes that the former mortality risk factors do not necessarily directly reflect. That is why efficient and reliable new prognostic predictor markers are of upmost importance and relevance for the future management of the disease. Monocytes are a heterogeneous population of effector cells with key roles in the maintenance and restoration of tissue integrity. Three distinct human monocyte subsets can be identified by flow cytometry: classical (CD14++/CD16–), intermediate (CD14++/CD16+) and non-classical (CD14–/CD16+). Little is known about the importance, relationship between the levels of the circulating monocytes and their distribution in heart failure, even less if these parameters could be used as a predictor markers for the progression of the disease. The main objective of the current project was to assess the relationship between the levels and distribution of the different circulating monocyte subsets and the length of its telomeres in outpatients with heart failure with adverse events, namely mortality and heart failure hospitalizations. Three cohorts of respectively 28, 400 and 101 ambulatory patients, consecutively treated at a multidisciplinary heart failure Clinic from December 2013 to May 2015 were included in the studies described in this doctoral thesis, independently of the data of their entry into the heart failure Clinic program. All study procedures were performed in accordance with all ethical standards and all participants provided written informed consent. Peripheral blood samples of all patients were extracted for subsequent analysis by flow cytometry. The samples were incubated directly by means of monoclonal antibodies with fluorocromes against monocyte specific surface antigens, type CD86 (or HLA -DR), CD14 and CD 16 and in parallel (in 100 samples) genetic markers (telomeres) were subsequently analyzed by flow cytometer (BD LSRFortessa) in the Department of Citolatry of the IGTP. The percentage distribution of each monocyte subset was analyzed and their absolute cell count (U/mL) was also determined quantitatively. We were able to establish an innovating, accurate and much less expensive method than established ones for simultaneously measuring the different monocyte subsets and the its relative telomere length. In our study, the intermediate subset was independently associated with all-cause death and the composite end-point of all-cause death or heart failure hospitalization, in multivariable analyses. The quantitative determination of the absolute cell count of each monocyte subset expressed by U/mL was superior from the prognostic point of view than the percentage of these monocyte subsets in outpatients with Heart failure. We observed about 22% reduction in telomere length over 1 year in the monocytes of our patients, being the baseline telomere length and change in telomere length not significantly associated with outcomes. Therefore, the change in telomere length is not likely to be a useful biomarker of heart failure progression. The monocytes and monocyte subsets could be used not only as a predictor factor but also might be taken into consideration as part of an immuno-modulation therapy in the future for the heart failure patients.

Date of Award	16 Jul 2019
Original language	English
Supervisor	Antonio Bayes Genis (Tutor) & Jose Lupon Roses (Director)