Cao Huy Thong - Novel Biomarkers for Predicting Poor Treatment Response in Heart Failure in Order to Guide Therapy

In this article, Cao Huy Thong of the Department of Cardiovascular Sciences describes his research exploring how proteins in our blood can be used to predict therapeutic responses for patients with heart failure.

About My Research

Heart failure is a complex clinical syndrome that occurs at the end stage of heart disease when the heart cannot pump enough blood to maintain an adequate circulation for the needs of the body. It is a major health problem in western countries with an overall population prevalence of 2-3% which rises sharply to 10-20% at 75 year of age. Despite advances in therapy for heart failure, improving clinical outcomes still remains a challenge for physicians with 50% of patients dying by 4 years and 40% of patients admitted are dead or rehospitalised within 1 year.

Even though blood samples are easily accessible, analysis of plasma is extremely challenging because proteins in blood have a wide dynamic concentration range with 10-12 orders of magnitude as well as a very high concentration of 50–80 g/L. Moreover, only 22 high abundant proteins comprise 99% of the plasma protein, so the challenge is to identify biomarkers within the 1% of medium and low abundant proteins which are masked by high abundant proteins.

The aim of this study is to discover proteins in plasma that are able to predict the difference in clinical response to standard therapy in patients with heart failure.

Research Approach

Heart failure patients who met inclusion and exclusion criteria were recruited.  Uptitration of ACE-inhibitors and β–blockers was performed over 6 months. Patients were followed up for clinical events such as death and heart failure hospitalisation within the next 24 months. In this study, we compared plasma proteins in 50 patients who responded to standard treatment (responders) with 50 patients who died or were re-hospitalised (non-responders). Plasma samples were first pooled and depleted of 14 high abundance proteins, which include albumin, IgG, antitrypsin, IgA, transferrin, haptoglobin, fibrinogen, alpha 2–macroglobulin, alpha 1–acid glycoprotein, IgM, apolipoprotein AI, apolipoprotein AII, complement C3 and transthyretin. The samples were then reduced and alkylated, before digestion with trypsin to peptides. Peptides were analysed on 2-dimensional liquid chromatography coupled to tandem mass spectrometry (2-D LC-MS/MS) in high definition mode which employed a high pH reverse phase liquid chromatography in the first step before separation with conventional low pH reverse phase columns in the second step. The Protein Lynx Global Server and the Progenesis software were employed to process the raw data as well as protein quantification to compare between the heart failure responder and non-responder groups.

Research Findings

A total of 434 proteins were identified in the plasma of heart failure patients. 220 commonly identified proteins in both groups were found to be over or under-expressed significantly, with 144 up-regulated proteins and 76 down-regulated proteins. 39 proteins identified were up-regulated and 16 proteins were down-regulated significantly in the heart failure non-responder group, with fold change ≥ 2 and p value ≤ 0.05. Several of these proteins have the potential to become novel biomarkers for predicting treatment response in heart failure which are classified according to 5 pathobiological processes operative in heart failure: (1) Neurohormones: Hepatocyte growth factor like protein (HGFL) and Insulin like growth factor II (IGF-II); (2) Vascular system: Intercellular adhesion molecule 2 (ICAM-2), Sex hormone binding globulin (SHBG) and Prostaglandin H2 D isomerase (PTGDS); (3) Inflammation: C reactive protein (CRP) and Mannose binding protein C (MBP-C); (4) Matrix and cellular remodelling: Retinol binding protein 4 (RBP-4); (5) Cardio-renal system: Cystatin C.

Proteins in Haert Failure Patients Who Resoponded to Standard Treatment

Plasma Proteins in Heart Failure (HF) Patients Who Responded to Standard Treatment

The measurements of these candidate biomarkers can provide information on the pathogenesis of heart failure and be able to predict who will respond to treatment in order to give guidance to medical therapy. For example, in heart failure patients with abnormally elevated levels of a marker for matrix and cellular remodelling as Retinol binding protein 4 (RBP-4), this may suggest that it could be beneficial to use a drug for reducing collagen deposition.

Candidate biomarkers will be further evaluated using other techniques such as a triple quadrupole mass spectrometry instrument or immunoassays with a larger number of samples.  The discovery of novel biomarkers in this study will not only help to understand the pathophysiology of heart failure better, but also lead to the development of a more personalised approach in predicting treatment response in order to give guidance to medical therapy. In this way, the unnecessary prescription of therapy to non-responders may be avoided (with cost and adverse effect implications) and novel therapeutic targets could be identified for design of therapies that may improve outcomes.

About Cao Huy Thong

Cao Huy ThongCao Huy Thong is a research student working towards completion of his doctoral degree in the Department of Cardiovascular Sciences. Thong's research is funded by the European Union FP7 Project (BIOSTAT-CHF).

Thong is supervised by Professor Leong Ng and Dr Don Jones.

Department of Cardiovascular Sciences
University of Leicester
Glenfield Hospital - Clinical Sciences Wing
Groby Road
Leicester
LE3 9QP

Thong will present his work at the Festival of Postgraduate Research 27 June 2013 - see Thong's Festival poster.

The Festival is open to all members of the University community and the public - book your place here.

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