Comparison of whole blood and peripheral blood mononuclear cell gene expression for evaluation of the perioperative inflammatory response in patients with advanced heart failure

Abstract

Background: Heart failure (HF) prevalence is increasing in the United States. Mechanical Circulatory Support (MCS) therapy is an option for Advanced HF (AdHF) patients. Perioperatively, multiorgan dysfunction (MOD) is linked to the effects of device implantation, augmented by preexisting HF. Early recognition of MOD allows for better diagnosis, treatment, and risk prediction. Gene expression profiling (GEP) was used to evaluate clinical phenotypes of peripheral blood mononuclear cells (PBMC) transcriptomes obtained from patients' blood samples. Whole blood (WB) samples are clinically more feasible, but their performance in comparison to PBMC samples has not been determined.

Methods: We collected blood samples from 31 HF patients (57±15 years old) undergoing cardiothoracic surgery and 7 healthy age-matched controls, between 2010 and 2011, at a single institution. WB and PBMC samples were collected at a single timepoint postoperatively (median day 8 postoperatively) (25-75% IQR 7-14 days) and subjected to Illumina single color Human BeadChip HT12 v4 whole genome expression array analysis. The Sequential Organ Failure Assessment (SOFA) score was used to characterize the severity of MOD into low (≤ 4 points), intermediate (5-11), and high (≥ 12) risk categories correlating with GEP.

Results: Results indicate that the direction of change in GEP of individuals with MOD as compared to controls is similar when determined from PBMC versus WB. The main enriched terms by Gene Ontology (GO) analysis included those involved in the inflammatory response, apoptosis, and other stress response related pathways. The data revealed 35 significant GO categories and 26 pathways overlapping between PBMC and WB. Additionally, class prediction using machine learning tools demonstrated that the subset of significant genes shared by PBMC and WB are sufficient to train as a predictor separating the SOFA groups.

Conclusion: GEP analysis of WB has the potential to become a clinical tool for immune-monitoring in patients with MOD.

Conflict of interest statement

Competing Interests: The authors declare that they have no competing interests.

Figures

Figure 1. Variability of methodologies in the processing of gene expression in WB and PBMC.

Figure 2. Flowchart of data analysis.

Figure 3. Clustered heatmap of the overlapping 333 genes in WB and PBMC shows highly correlated gene expression patterns.

Figure 4. RT-qPCR validation of three differentially expressed genes within PBMC and WB subgroups, within SOFA groups.

Darker colors correspond to higher magnitude of fold change. Fold changes showed similar patterns between all 10 genes, 9 of which are down-regulated, and 1 of which is up-regulated. 7 of 10 genes showed similar patterns between PBMC and WB and also within SOFA score groups according to our microarray and PCR results. 2 of 10 genes (IL11RA and GRB10) show an opposite result in HIGH PCR (PBMC) and low/med array (WB) correspondingly. Only 1 gene, MAP4K1, shows an opposite result between SOFA score groups.